The Scientific World Journal: Communications http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. Storage-Efficient 16-Bit Hybrid IP Traceback with Single Packet Mon, 20 Oct 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/659894/ Since adversaries may spoof their source IPs in the attacks, traceback schemes have been proposed to identify the attack source. However, some of these schemes’ storage requirements increase with packet numbers. Some even have false positives because they use an IP header’s fragment offset for marking. Thus, we propose a 16-bit single packet hybrid IP traceback scheme that combines packet marking and packet logging with high accuracy and low storage requirement. The size of our log tables can be bounded by route numbers. We also set a threshold to determine whether an upstream interface number is stored in a log table or in a marking field, so as to balance the logging frequency and our computational loads. Because we store user interface information on small-degree routers, compared with current single packet traceback schemes, ours can have the lowest storage requirements. Besides, our traceback achieves zero false positive/negative rates and guarantees reassembly of fragmented packets at the destination. Ming Hour Yang Copyright © 2014 Ming Hour Yang. All rights reserved. Investigation of a New Handover Approach in LTE and WiMAX Tue, 14 Oct 2014 07:33:09 +0000 http://www.hindawi.com/journals/tswj/2014/246206/ Nowadays, one of the most important challenges in heterogeneous networks is the connection consistency between the mobile station and the base stations. Furthermore, along the roaming process between the mobile station and the base station, the system performance degrades significantly due to the interferences from neighboring base stations, handovers to inaccurate base station and inappropriate technology selection. In this paper, several algorithms are proposed to improve mobile station performance and seamless mobility across the long-term evolution (LTE) and Worldwide Interoperability for Microwave Access (WiMAX) technologies, along with a minimum number of redundant handovers. Firstly, the enhanced global positioning system (GPS) and the novel received signal strength (RSS) prediction approaches are suggested to predict the target base station accurately. Then, the multiple criteria with two thresholds algorithm is proposed to prioritize the selection between LTE and WiMAX as the target technology. In addition, this study also covers the intercell and cochannel interference reduction by adjusting the frequency reuse ratio 3 (FRR3) to work with LTE and WiMAX. The obtained results demonstrate high next base station prediction efficiency and high accuracy for both horizontal and vertical handovers. Moreover, the received signal strength is kept at levels higher than the threshold, while maintaining low connection cost and delay within acceptable levels. In order to highlight the combination of the proposed algorithms’ performance, it is compared with the existing RSS and multiple criteria handover decision algorithms. Mohammad Nour Hindia, Ahmed Wasif Reza, and Kamarul Ariffin Noordin Copyright © 2014 Mohammad Nour Hindia et al. All rights reserved. Analysis of Blocking Rate and Bandwidth Usage of Mobile IPTV Services in Wireless Cellular Networks Tue, 14 Oct 2014 07:03:14 +0000 http://www.hindawi.com/journals/tswj/2014/215710/ Mobile IPTV services over wireless cellular networks become more and more popular, owing to the significant growth in access bandwidth of wireless cellular networks such as 3G/4G and WiMAX. However, the spectrum resources of wireless cellular networks is rare. How to enhance the spectral efficiency of mobile networks becomes an important issue. Unicast, broadcast, and multicast are the most important transport schemes for offering mobile IPTV services over wireless cellular networks. Therefore, bandwidth usages and blocking rates of unicast, broadcast, and multicast IPTV services were analyzed and compared in this paper. Simulations were also conducted to validate the analytical results. Numerical results demonstrate that the presented analysis is correct, and multicast scheme achieves the best bandwidth usage and blocking rate performance, relative to the other two schemes. Mingfu Li Copyright © 2014 Mingfu Li. All rights reserved. Password-Only Authenticated Three-Party Key Exchange Proven Secure against Insider Dictionary Attacks Thu, 18 Sep 2014 05:56:52 +0000 http://www.hindawi.com/journals/tswj/2014/802359/ While a number of protocols for password-only authenticated key exchange (PAKE) in the 3-party setting have been proposed, it still remains a challenging task to prove the security of a 3-party PAKE protocol against insider dictionary attacks. To the best of our knowledge, there is no 3-party PAKE protocol that carries a formal proof, or even definition, of security against insider dictionary attacks. In this paper, we present the first 3-party PAKE protocol proven secure against both online and offline dictionary attacks as well as insider and outsider dictionary attacks. Our construct can be viewed as a protocol compiler that transforms any 2-party PAKE protocol into a 3-party PAKE protocol with 2 additional rounds of communication. We also present a simple and intuitive approach of formally modelling dictionary attacks in the password-only 3-party setting, which significantly reduces the complexity of proving the security of 3-party PAKE protocols against dictionary attacks. In addition, we investigate the security of the well-known 3-party PAKE protocol, called GPAKE, due to Abdalla et al. (2005, 2006), and demonstrate that the security of GPAKE against online dictionary attacks depends heavily on the composition of its two building blocks, namely a 2-party PAKE protocol and a 3-party key distribution protocol. Junghyun Nam, Kim-Kwang Raymond Choo, Juryon Paik, and Dongho Won Copyright © 2014 Junghyun Nam et al. All rights reserved. Towards Internet QoS Provisioning Based on Generic Distributed QoS Adaptive Routing Engine Wed, 17 Sep 2014 09:56:07 +0000 http://www.hindawi.com/journals/tswj/2014/694847/ Increasing efficiency and quality demands of modern Internet technologies drive today’s network engineers to seek to provide quality of service (QoS). Internet QoS provisioning gives rise to several challenging issues. This paper introduces a generic distributed QoS adaptive routing engine (DQARE) architecture based on OSPFxQoS. The innovation of the proposed work in this paper is its undependability on the used QoS architectures and, moreover, splitting of the control strategy from data forwarding mechanisms, so we guarantee a set of absolute stable mechanisms on top of which Internet QoS can be built. DQARE architecture is furnished with three relevant traffic control schemes, namely, service differentiation, QoS routing, and traffic engineering. The main objective of this paper is to (i) provide a general configuration guideline for service differentiation, (ii) formalize the theoretical properties of different QoS routing algorithms and then introduce a QoS routing algorithm (QOPRA) based on dynamic programming technique, and (iii) propose QoS multipath forwarding (QMPF) model for paths diversity exploitation. NS2-based simulations proved the DQARE superiority in terms of delay, packet delivery ratio, throughput, and control overhead. Moreover, extensive simulations are used to compare the proposed QOPRA algorithm and QMPF model with their counterparts in the literature. Amira Y. Haikal, M. Badawy, and Hesham A. Ali Copyright © 2014 Amira Y. Haikal et al. All rights reserved. Design and Implementation of a VoIP Broadcasting Service over Embedded Systems in a Heterogeneous Network Environment Mon, 15 Sep 2014 08:21:04 +0000 http://www.hindawi.com/journals/tswj/2014/917060/ As the digitization is integrated into daily life, media including video and audio are heavily transferred over the Internet nowadays. Voice-over-Internet Protocol (VoIP), the most popular and mature technology, becomes the focus attracting many researches and investments. However, most of the existing studies focused on a one-to-one communication model in a homogeneous network, instead of one-to-many broadcasting model among diverse embedded devices in a heterogeneous network. In this paper, we present the implementation of a VoIP broadcasting service on the open source—Linphone—in a heterogeneous network environment, including WiFi, 3G, and LAN networks. The proposed system featuring VoIP broadcasting over heterogeneous networks can be integrated with heterogeneous agile devices, such as embedded devices or mobile phones. VoIP broadcasting over heterogeneous networks can be integrated into modern smartphones or other embedded devices; thus when users run in a traditional AM/FM signal unreachable area, they still can receive the broadcast voice through the IP network. Also, comprehensive evaluations are conducted to verify the effectiveness of the proposed implementation. Jenq-Shiou Leu, Wei-Hsiang Lin, Wen-Bin Hsieh, and Chien-Chih Lo Copyright © 2014 Jenq-Shiou Leu et al. All rights reserved. Security Enhanced EMV-Based Mobile Payment Protocol Mon, 15 Sep 2014 06:29:54 +0000 http://www.hindawi.com/journals/tswj/2014/864571/ Near field communication has enabled customers to put their credit cards into a smartphone and use the phone for credit card transaction. But EMV contactless payment allows unauthorized readers to access credit cards. Besides, in offline transaction, a merchant’s reader cannot verify whether a card has been revoked. Therefore, we propose an EMV-compatible payment protocol to mitigate the transaction risk. And our modifications to the EMV standard are transparent to merchants and users. We also encrypt the communications between a card and a reader to prevent eavesdropping on sensitive data. The protocol is able to resist impersonation attacks and to avoid the security threats in EMV. In offline transactions, our scheme requires a user to apply for a temporary offline certificate in advance. With the certificate, banks no longer need to lower customer’s credits for risk control, and users can have online-equivalent credits in offline transactions. Ming-Hour Yang Copyright © 2014 Ming-Hour Yang. All rights reserved. A Design of Irregular Grid Map for Large-Scale Wi-Fi LAN Fingerprint Positioning Systems Mon, 15 Sep 2014 06:05:39 +0000 http://www.hindawi.com/journals/tswj/2014/203419/ The rapid growth of mobile communication and the proliferation of smartphones have drawn significant attention to location-based services (LBSs). One of the most important factors in the vitalization of LBSs is the accurate position estimation of a mobile device. The Wi-Fi positioning system (WPS) is a new positioning method that measures received signal strength indication (RSSI) data from all Wi-Fi access points (APs) and stores them in a large database as a form of radio fingerprint map. Because of the millions of APs in urban areas, radio fingerprints are seriously contaminated and confused. Moreover, the algorithmic advances for positioning face computational limitation. Therefore, we present a novel irregular grid structure and data analytics for efficient fingerprint map management. The usefulness of the proposed methodology is presented using the actual radio fingerprint measurements taken throughout Seoul, Korea. Jae-Hoon Kim, Kyoung Sik Min, and Woon-Young Yeo Copyright © 2014 Jae-Hoon Kim et al. All rights reserved. Security Analysis and Improvement of an Anonymous Authentication Scheme for Roaming Services Thu, 11 Sep 2014 06:08:39 +0000 http://www.hindawi.com/journals/tswj/2014/687879/ An anonymous authentication scheme for roaming services in global mobility networks allows a mobile user visiting a foreign network to achieve mutual authentication and session key establishment with the foreign-network operator in an anonymous manner. In this work, we revisit He et al.’s anonymous authentication scheme for roaming services and present previously unpublished security weaknesses in the scheme: (1) it fails to provide user anonymity against any third party as well as the foreign agent, (2) it cannot protect the passwords of mobile users due to its vulnerability to an offline dictionary attack, and (3) it does not achieve session-key security against a man-in-the-middle attack. We also show how the security weaknesses of He et al.’s scheme can be addressed without degrading the efficiency of the scheme. Youngsook Lee and Juryon Paik Copyright © 2014 Youngsook Lee and Juryon Paik. All rights reserved. Security Enhanced Anonymous Multiserver Authenticated Key Agreement Scheme Using Smart Cards and Biometrics Mon, 08 Sep 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/281305/ An anonymous user authentication scheme allows a user, who wants to access a remote application server, to achieve mutual authentication and session key establishment with the server in an anonymous manner. To enhance the security of such authentication schemes, recent researches combined user’s biometrics with a password. However, these authentication schemes are designed for single server environment. So when a user wants to access different application servers, the user has to register many times. To solve this problem, Chuang and Chen proposed an anonymous multiserver authenticated key agreement scheme using smart cards together with passwords and biometrics. Chuang and Chen claimed that their scheme not only supports multiple servers but also achieves various security requirements. However, we show that this scheme is vulnerable to a masquerade attack, a smart card attack, a user impersonation attack, and a DoS attack and does not achieve perfect forward secrecy. We also propose a security enhanced anonymous multiserver authenticated key agreement scheme which addresses all the weaknesses identified in Chuang and Chen’s scheme. Younsung Choi, Junghyun Nam, Donghoon Lee, Jiye Kim, Jaewook Jung, and Dongho Won Copyright © 2014 Younsung Choi et al. All rights reserved. A Novel Vehicle Stationary Detection Utilizing Map Matching and IMU Sensors Sun, 07 Sep 2014 12:44:42 +0000 http://www.hindawi.com/journals/tswj/2014/597180/ Precise navigation is a vital need for many modern vehicular applications. The global positioning system (GPS) cannot provide continuous navigation information in urban areas. The widely used inertial navigation system (INS) can provide full vehicle state at high rates. However, the accuracy diverges quickly in low cost microelectromechanical systems (MEMS) based INS due to bias, drift, noise, and other errors. These errors can be corrected in a stationary state. But detecting stationary state is a challenging task. A novel stationary state detection technique from the variation of acceleration, heading, and pitch and roll of an attitude heading reference system (AHRS) built from the inertial measurement unit (IMU) sensors is proposed. Besides, the map matching (MM) algorithm detects the intersections where the vehicle is likely to stop. Combining these two results, the stationary state is detected with a smaller timing window of 3 s. A longer timing window of 5 s is used when the stationary state is detected only from the AHRS. The experimental results show that the stationary state is correctly identified and the position error is reduced to 90% and outperforms previously reported work. The proposed algorithm would help to reduce INS errors and enhance the performance of the navigation system. Md. Syedul Amin, Mamun Bin Ibne Reaz, Salwa Sheikh Nasir, Mohammad Arif Sobhan Bhuiyan, and Mohd. Alauddin Mohd. Ali Copyright © 2014 Md. Syedul Amin et al. All rights reserved. Provably-Secure (Chinese Government) SM2 and Simplified SM2 Key Exchange Protocols Tue, 02 Sep 2014 09:54:49 +0000 http://www.hindawi.com/journals/tswj/2014/825984/ We revisit the SM2 protocol, which is widely used in Chinese commercial applications and by Chinese government agencies. Although it is by now standard practice for protocol designers to provide security proofs in widely accepted security models in order to assure protocol implementers of their security properties, the SM2 protocol does not have a proof of security. In this paper, we prove the security of the SM2 protocol in the widely accepted indistinguishability-based Bellare-Rogaway model under the elliptic curve discrete logarithm problem (ECDLP) assumption. We also present a simplified and more efficient version of the SM2 protocol with an accompanying security proof. Ang Yang, Junghyun Nam, Moonseong Kim, and Kim-Kwang Raymond Choo Copyright © 2014 Ang Yang et al. All rights reserved. On the Security of a Simple Three-Party Key Exchange Protocol without Server’s Public Keys Mon, 01 Sep 2014 08:50:10 +0000 http://www.hindawi.com/journals/tswj/2014/479534/ Authenticated key exchange protocols are of fundamental importance in securing communications and are now extensively deployed for use in various real-world network applications. In this work, we reveal major previously unpublished security vulnerabilities in the password-based authenticated three-party key exchange protocol according to Lee and Hwang (2010): (1) the Lee-Hwang protocol is susceptible to a man-in-the-middle attack and thus fails to achieve implicit key authentication; (2) the protocol cannot protect clients’ passwords against an offline dictionary attack; and (3) the indistinguishability-based security of the protocol can be easily broken even in the presence of a passive adversary. We also propose an improved password-based authenticated three-party key exchange protocol that addresses the security vulnerabilities identified in the Lee-Hwang protocol. Junghyun Nam, Kim-Kwang Raymond Choo, Minkyu Park, Juryon Paik, and Dongho Won Copyright © 2014 Junghyun Nam et al. All rights reserved. Greedy Data Transportation Scheme with Hard Packet Deadlines for Wireless Ad Hoc Networks Mon, 01 Sep 2014 05:52:00 +0000 http://www.hindawi.com/journals/tswj/2014/815123/ We present a greedy data transportation scheme with hard packet deadlines in ad hoc sensor networks of stationary nodes and multiple mobile nodes with scheduled trajectory path and arrival time. In the proposed routing strategy, each stationary ad hoc node en route decides whether to relay a shortest-path stationary node toward destination or a passing-by mobile node that will carry closer to destination. We aim to utilize mobile nodes to minimize the total routing cost as far as the selected route can satisfy the end-to-end packet deadline. We evaluate our proposed routing algorithm in terms of routing cost, packet delivery ratio, packet delivery time, and usability of mobile nodes based on network level simulations. Simulation results show that our proposed algorithm fully exploits the remaining time till packet deadline to turn into networking benefits of reducing the overall routing cost and improving packet delivery performance. Also, we demonstrate that the routing scheme guarantees packet delivery with hard deadlines, contributing to QoS improvement in various network services. HyungJune Lee Copyright © 2014 HyungJune Lee. All rights reserved. Precoding Method Interference Management for Quasi-EVD Channel Thu, 28 Aug 2014 13:03:42 +0000 http://www.hindawi.com/journals/tswj/2014/678578/ The Cholesky decomposition-block diagonalization (CD-BD) interference alignment (IA) for a multiuser multiple input multiple output (MU-MIMO) relay system is proposed, which designs precoders for the multiple access channel (MAC) by employing the singular value decomposition (SVD) as well as the mean square error (MSE) detector for the broadcast Hermitian channel (BHC) taken advantage of in our design. Also, in our proposed CD-BD IA algorithm, the relaying function is made use to restructure the quasieigenvalue decomposition (quasi-EVD) equivalent channel. This approach used for the design of BD precoding matrix can significantly reduce the computational complexity and proposed algorithm can address several optimization criteria, which is achieved by designing the precoding matrices in two steps. In the first step, we use Cholesky decomposition to maximize the sum-of-rate (SR) with the minimum mean square error (MMSE) detection. In the next step, we optimize the system BER performance with the overlap of the row spaces spanned by the effective channel matrices of different users. By iterating the closed form of the solution, we are able not only to maximize the achievable sum-of-rate (ASR), but also to minimize the BER performance at a high signal-to-noise ratio (SNR) region. Wei Duan, Wei Song, Sang Seob Song, and Moon Ho Lee Copyright © 2014 Wei Duan et al. All rights reserved. Self-Adaptive Trust Based ABR Protocol for MANETs Using Q-Learning Thu, 28 Aug 2014 06:30:28 +0000 http://www.hindawi.com/journals/tswj/2014/452362/ Mobile ad hoc networks (MANETs) are a collection of mobile nodes with a dynamic topology. MANETs work under scalable conditions for many applications and pose different security challenges. Due to the nomadic nature of nodes, detecting misbehaviour is a complex problem. Nodes also share routing information among the neighbours in order to find the route to the destination. This requires nodes to trust each other. Thus we can state that trust is a key concept in secure routing mechanisms. A number of cryptographic protection techniques based on trust have been proposed. Q-learning is a recently used technique, to achieve adaptive trust in MANETs. In comparison to other machine learning computational intelligence techniques, Q-learning achieves optimal results. Our work focuses on computing a score using Q-learning to weigh the trust of a particular node over associativity based routing (ABR) protocol. Thus secure and stable route is calculated as a weighted average of the trust value of the nodes in the route and associativity ticks ensure the stability of the route. Simulation results show that Q-learning based trust ABR protocol improves packet delivery ratio by 27% and reduces the route selection time by 40% over ABR protocol without trust calculation. Anitha Vijaya Kumar and Akilandeswari Jeyapal Copyright © 2014 Anitha Vijaya Kumar and Akilandeswari Jeyapal. All rights reserved. A QoS Aware Resource Allocation Strategy for 3D A/V Streaming in OFDMA Based Wireless Systems Thu, 28 Aug 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/419236/ Three-dimensional (3D) video is expected to be a “killer app” for OFDMA-based broadband wireless systems. The main limitation of 3D video streaming over a wireless system is the shortage of radio resources due to the large size of the 3D traffic. This paper presents a novel resource allocation strategy to address this problem. In the paper, the video-plus-depth 3D traffic type is considered. The proposed resource allocation strategy focuses on the relationship between 2D video and the depth map, handling them with different priorities. It is formulated as an optimization problem and is solved using a suboptimal heuristic algorithm. Numerical results show that the proposed scheme provides a better quality of service compared to conventional schemes. Young-uk Chung, Yong-Hoon Choi, Suwon Park, and Hyukjoon Lee Copyright © 2014 Young-uk Chung et al. All rights reserved. Design of a Broadband Band-Pass Filter with Notch-Band Using New Models of Coupled Transmission Lines Thu, 28 Aug 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/238717/ We intend to design a broadband band-pass filter with notch-band, which uses coupled transmission lines in the structure, using new models of coupled transmission lines. In order to realize and present the new model, first, previous models will be simulated in the ADS program. Then, according to the change of their equations and consequently change of basic parameters of these models, optimization and dependency among these parameters and also their frequency response are attended and results of these changes in order to design a new filter are converged. Navid Daryasafar, Somaye Baghbani, Mohammad Naser Moghaddasi, and Ramezanali Sadeghzade Copyright © 2014 Navid Daryasafar et al. All rights reserved. A Novel Error Detection due to Joint CRC Aided Denoise-and-Forward Network Coding for Two-Way Relay Channels Wed, 27 Aug 2014 06:36:19 +0000 http://www.hindawi.com/journals/tswj/2014/470324/ In wireless two-way (TW) relay channels, denoise-and-forward (DNF) network coding (NC) is a promising technique to achieve spectral efficiency. However, unsuccessful detection at relay severely deteriorates the diversity gain, as well as end-to-end pairwise error probability (PEP). To handle this issue, a novel joint cyclic redundancy code (CRC) check method (JCRC) is proposed in this paper by exploiting the property of two NC combined CRC codewords. Firstly, the detection probability bounds of the proposed method are derived to prove its efficiency in evaluating the reliability of NC signals. On the basis of that, three JCRC aided TW DNF NC schemes are proposed, and the corresponding PEP performances are also derived. Numerical results reveal that JCRC aided TW DNF NC has similar PEP comparing with the separate CRC one, while the complexity is reduced to half. Besides, it demonstrates that the proposed schemes outperform the conventional one with log-likelihood ratio threshold. Yulun Cheng and Longxiang Yang Copyright © 2014 Yulun Cheng and Longxiang Yang. All rights reserved. A Comprehensive Propagation Prediction Model Comprising Microfacet Based Scattering and Probability Based Coverage Optimization Algorithm Mon, 18 Aug 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/601729/ Although ray tracing based propagation prediction models are popular for indoor radio wave propagation characterization, most of them do not provide an integrated approach for achieving the goal of optimum coverage, which is a key part in designing wireless network. In this paper, an accelerated technique of three-dimensional ray tracing is presented, where rough surface scattering is included for making a more accurate ray tracing technique. Here, the rough surface scattering is represented by microfacets, for which it becomes possible to compute the scattering field in all possible directions. New optimization techniques, like dual quadrant skipping (DQS) and closest object finder (COF), are implemented for fast characterization of wireless communications and making the ray tracing technique more efficient. In conjunction with the ray tracing technique, probability based coverage optimization algorithm is accumulated with the ray tracing technique to make a compact solution for indoor propagation prediction. The proposed technique decreases the ray tracing time by omitting the unnecessary objects for ray tracing using the DQS technique and by decreasing the ray-object intersection time using the COF technique. On the other hand, the coverage optimization algorithm is based on probability theory, which finds out the minimum number of transmitters and their corresponding positions in order to achieve optimal indoor wireless coverage. Both of the space and time complexities of the proposed algorithm surpass the existing algorithms. For the verification of the proposed ray tracing technique and coverage algorithm, detailed simulation results for different scattering factors, different antenna types, and different operating frequencies are presented. Furthermore, the proposed technique is verified by the experimental results. A. S. M. Zahid Kausar, Ahmed Wasif Reza, Lau Chun Wo, and Harikrishnan Ramiah Copyright © 2014 A. S. M. Zahid Kausar et al. All rights reserved. Spontaneous Ad Hoc Mobile Cloud Computing Network Sun, 17 Aug 2014 11:00:43 +0000 http://www.hindawi.com/journals/tswj/2014/232419/ Cloud computing helps users and companies to share computing resources instead of having local servers or personal devices to handle the applications. Smart devices are becoming one of the main information processing devices. Their computing features are reaching levels that let them create a mobile cloud computing network. But sometimes they are not able to create it and collaborate actively in the cloud because it is difficult for them to build easily a spontaneous network and configure its parameters. For this reason, in this paper, we are going to present the design and deployment of a spontaneous ad hoc mobile cloud computing network. In order to perform it, we have developed a trusted algorithm that is able to manage the activity of the nodes when they join and leave the network. The paper shows the network procedures and classes that have been designed. Our simulation results using Castalia show that our proposal presents a good efficiency and network performance even by using high number of nodes. Raquel Lacuesta, Jaime Lloret, Sandra Sendra, and Lourdes Peñalver Copyright © 2014 Raquel Lacuesta et al. All rights reserved. An Active Learning Approach with Uncertainty, Representativeness, and Diversity Mon, 11 Aug 2014 12:12:26 +0000 http://www.hindawi.com/journals/tswj/2014/827586/ Big data from the Internet of Things may create big challenge for data classification. Most active learning approaches select either uncertain or representative unlabeled instances to query their labels. Although several active learning algorithms have been proposed to combine the two criteria for query selection, they are usually ad hoc in finding unlabeled instances that are both informative and representative and fail to take the diversity of instances into account. We address this challenge by presenting a new active learning framework which considers uncertainty, representativeness, and diversity creation. The proposed approach provides a systematic way for measuring and combining the uncertainty, representativeness, and diversity of an instance. Firstly, use instances’ uncertainty and representativeness to constitute the most informative set. Then, use the kernel -means clustering algorithm to filter the redundant samples and the resulting samples are queried for labels. Extensive experimental results show that the proposed approach outperforms several state-of-the-art active learning approaches. Tianxu He, Shukui Zhang, Jie Xin, Pengpeng Zhao, Jian Wu, Xuefeng Xian, Chunhua Li, and Zhiming Cui Copyright © 2014 Tianxu He et al. All rights reserved. Heavy Traffic Feasible Hybrid Intracycle and Cyclic Sleep for Power Saving in 10G-EPON Mon, 11 Aug 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/497379/ Energy consumption in optical access networks costs carriers substantial operational expense (OPEX) every year and is one of contributing factors for the global warming. To reduce energy consumption in the 10-gigabit Ethernet passive optical network (10G-EPON), a hybrid intracycle and cyclic sleep mechanism is proposed in this paper. Under heavy traffic load, optical network units (ONUs) can utilize short idle slots within each scheduling cycle to enter intracycle sleep without postponing data transmission. In this way, energy conservation is achieved even under heavy traffic load with quality of service (QoS) guarantee. Under light traffic load, ONUs perform long cyclic sleep for several scheduling cycles. The adoption of cyclic sleep instead of intracycle sleep under light traffic load can reduce unnecessary frequent transitions between sleep and full active work caused by using intracycle sleep. Further, the Markov chain of the proposed mechanism is established. The performances of the proposed mechanism and existing approaches are analyzed quantitatively based on the chain. For the proposed mechanism, power saving ability with QoS guarantee even under heavy traffic and better power saving performance than existing approaches are verified by the quantitative analysis. Moreover, simulations validate the above conclusions based on the chain. Xintian Hu, Liqian Wang, Zhiguo Zhang, and Xue Chen Copyright © 2014 Xintian Hu et al. All rights reserved. Spatiotemporal Access Model Based on Reputation for the Sensing Layer of the IoT Wed, 06 Aug 2014 11:40:38 +0000 http://www.hindawi.com/journals/tswj/2014/671038/ Access control is a key technology in providing security in the Internet of Things (IoT). The mainstream security approach proposed for the sensing layer of the IoT concentrates only on authentication while ignoring the more general models. Unreliable communications and resource constraints make the traditional access control techniques barely meet the requirements of the sensing layer of the IoT. In this paper, we propose a model that combines space and time with reputation to control access to the information within the sensing layer of the IoT. This model is called spatiotemporal access control based on reputation (STRAC). STRAC uses a lattice-based approach to decrease the size of policy bases. To solve the problem caused by unreliable communications, we propose both nondeterministic authorizations and stochastic authorizations. To more precisely manage the reputation of nodes, we propose two new mechanisms to update the reputation of nodes. These new approaches are the authority-based update mechanism (AUM) and the election-based update mechanism (EUM). We show how the model checker UPPAAL can be used to analyze the spatiotemporal access control model of an application. Finally, we also implement a prototype system to demonstrate the efficiency of our model. Yunchuan Guo, Lihua Yin, Chao Li, and Junyan Qian Copyright © 2014 Yunchuan Guo et al. All rights reserved. An Analysis of Security System for Intrusion in Smartphone Environment Tue, 05 Aug 2014 11:49:34 +0000 http://www.hindawi.com/journals/tswj/2014/983901/ There are many malware applications in Smartphone. Smartphone’s users may become unaware if their data has been recorded and stolen by intruders via malware. Smartphone—whether for business or personal use—may not be protected from malwares. Thus, monitoring, detecting, tracking, and notification (MDTN) have become the main purpose of the writing of this paper. MDTN is meant to enable Smartphone to prevent and reduce the number of cybercrimes. The methods are shown to be effective in protecting Smartphone and isolating malware and sending warning in the form of notification to the user about the danger in progress. In particular, (a) MDTN process is possible and will be enabled for Smartphone environment. (b) The methods are shown to be an advanced security for private sensitive data of the Smartphone user. Maya Louk, Hyotaek Lim, and HoonJae Lee Copyright © 2014 Maya Louk et al. All rights reserved. Compact Double-P Slotted Inset-Fed Microstrip Patch Antenna on High Dielectric Substrate Tue, 05 Aug 2014 09:32:48 +0000 http://www.hindawi.com/journals/tswj/2014/909854/ This paper presents a compact sized inset-fed rectangular microstrip patch antenna embedded with double-P slots. The proposed antenna has been designed and fabricated on ceramic-PTFE composite material substrate of high dielectric constant value. The measurement results from the fabricated prototype of the antenna show −10 dB reflection coefficient bandwidths of 200 MHz and 300 MHz with center resonant frequency of 1.5 GHz and 4 GHz, respectively. The fabricated antenna has attained gains of 3.52 dBi with 81% radiation efficiency and 5.72 dBi with 87% radiation efficiency for lower band and upper band, respectively. The measured E- and H-plane radiation patterns are also presented for better understanding. Good agreement between the simulation and measurement results and consistent radiation patterns make the proposed antenna suitable for GPS and C-band applications. M. R. Ahsan, M. T. Islam, M. Habib Ullah, W. N. L. Mahadi, and T. A. Latef Copyright © 2014 M. R. Ahsan et al. All rights reserved. SmartMal: A Service-Oriented Behavioral Malware Detection Framework for Mobile Devices Tue, 05 Aug 2014 06:15:35 +0000 http://www.hindawi.com/journals/tswj/2014/101986/ This paper presents SmartMal—a novel service-oriented behavioral malware detection framework for vehicular and mobile devices. The highlight of SmartMal is to introduce service-oriented architecture (SOA) concepts and behavior analysis into the malware detection paradigms. The proposed framework relies on client-server architecture, the client continuously extracts various features and transfers them to the server, and the server’s main task is to detect anomalies using state-of-art detection algorithms. Multiple distributed servers simultaneously analyze the feature vector using various detectors and information fusion is used to concatenate the results of detectors. We also propose a cycle-based statistical approach for mobile device anomaly detection. We accomplish this by analyzing the users’ regular usage patterns. Empirical results suggest that the proposed framework and novel anomaly detection algorithm are highly effective in detecting malware on Android devices. Chao Wang, Zhizhong Wu, Xi Li, Xuehai Zhou, Aili Wang, and Patrick C. K. Hung Copyright © 2014 Chao Wang et al. All rights reserved. A Decentralized Fuzzy C-Means-Based Energy-Efficient Routing Protocol for Wireless Sensor Networks Tue, 05 Aug 2014 05:25:54 +0000 http://www.hindawi.com/journals/tswj/2014/647281/ Energy conservation in wireless sensor networks (WSNs) is a vital consideration when designing wireless networking protocols. In this paper, we propose a Decentralized Fuzzy Clustering Protocol, named DCFP, which minimizes total network energy dissipation to promote maximum network lifetime. The process of constructing the infrastructure for a given WSN is performed only once at the beginning of the protocol at a base station, which remains unchanged throughout the network’s lifetime. In this initial construction step, a fuzzy C-means algorithm is adopted to allocate sensor nodes into their most appropriate clusters. Subsequently, the protocol runs its rounds where each round is divided into a CH-Election phase and a Data Transmission phase. In the CH-Election phase, the election of new cluster heads is done locally in each cluster where a new multicriteria objective function is proposed to enhance the quality of elected cluster heads. In the Data Transmission phase, the sensing and data transmission from each sensor node to their respective cluster head is performed and cluster heads in turn aggregate and send the sensed data to the base station. Simulation results demonstrate that the proposed protocol improves network lifetime, data delivery, and energy consumption compared to other well-known energy-efficient protocols. Osama Moh’d Alia Copyright © 2014 Osama Moh’d Alia. All rights reserved. Indoor Positioning in Wireless Local Area Networks with Online Path-Loss Parameter Estimation Mon, 04 Aug 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/986714/ Location based services are gathering an even wider interest also in indoor environments and urban canyons, where satellite systems like GPS are no longer accurate. A much addressed solution for estimating the user position exploits the received signal strengths (RSS) in wireless local area networks (WLANs), which are very common nowadays. However, the performances of RSS based location systems are still unsatisfactory for many applications, due to the difficult modeling of the propagation channel, whose features are affected by severe changes. In this paper we propose a localization algorithm which takes into account the nonstationarity of the working conditions by estimating and tracking the key parameters of RSS propagation. It is based on a Sequential Monte Carlo realization of the optimal Bayesian estimation scheme, whose functioning is improved by exploiting the Rao-Blackwellization rationale. Two key statistical models for RSS characterization are deeply analyzed, by presenting effective implementations of the proposed scheme and by assessing the positioning accuracy by extensive computer experiments. Many different working conditions are analyzed by simulated data and corroborated through the validation in a real world scenario. Luigi Bruno, Paolo Addesso, and Rocco Restaino Copyright © 2014 Luigi Bruno et al. All rights reserved. Describing the Access Network by means of Router Buffer Modelling: A New Methodology Thu, 24 Jul 2014 10:01:40 +0000 http://www.hindawi.com/journals/tswj/2014/238682/ The behaviour of the routers’ buffer may affect the quality of service (QoS) of network services under certain conditions, since it may modify some traffic characteristics, as delay or jitter, and may also drop packets. As a consequence, the characterization of the buffer is interesting, especially when multimedia flows are transmitted and even more if they transport information with real-time requirements. This work presents a new methodology with the aim of determining the technical and functional characteristics of real buffers (i.e., behaviour, size, limits, and input and output rate) of a network path. It permits the characterization of intermediate buffers of different devices in a network path across the Internet. Luis Sequeira, Julián Fernández-Navajas, Jose Saldana, José Ramón Gállego, and María Canales Copyright © 2014 Luis Sequeira et al. All rights reserved. Beamforming Transmission in IEEE 802.11ac under Time-Varying Channels Thu, 24 Jul 2014 09:37:31 +0000 http://www.hindawi.com/journals/tswj/2014/920937/ The IEEE 802.11ac wireless local area network (WLAN) standard has adopted beamforming (BF) schemes to improve spectral efficiency and throughput with multiple antennas. To design the transmit beam, a channel sounding process to feedback channel state information (CSI) is required. Due to sounding overhead, throughput increases with the amount of transmit data under static channels. Under practical channel conditions with mobility, however, the mismatch between the transmit beam and the channel at transmission time causes performance loss when transmission duration after channel sounding is too long. When the fading rate, payload size, and operating signal-to-noise ratio are given, the optimal transmission duration (i.e., packet length) can be determined to maximize throughput. The relationship between packet length and throughput is also investigated for single-user and multiuser BF modes. Heejung Yu and Taejoon Kim Copyright © 2014 Heejung Yu and Taejoon Kim. All rights reserved. A Parallel Decoding Algorithm for Short Polar Codes Based on Error Checking and Correcting Wed, 23 Jul 2014 07:25:43 +0000 http://www.hindawi.com/journals/tswj/2014/895782/ We propose a parallel decoding algorithm based on error checking and correcting to improve the performance of the short polar codes. In order to enhance the error-correcting capacity of the decoding algorithm, we first derive the error-checking equations generated on the basis of the frozen nodes, and then we introduce the method to check the errors in the input nodes of the decoder by the solutions of these equations. In order to further correct those checked errors, we adopt the method of modifying the probability messages of the error nodes with constant values according to the maximization principle. Due to the existence of multiple solutions of the error-checking equations, we formulate a CRC-aided optimization problem of finding the optimal solution with three different target functions, so as to improve the accuracy of error checking. Besides, in order to increase the throughput of decoding, we use a parallel method based on the decoding tree to calculate probability messages of all the nodes in the decoder. Numerical results show that the proposed decoding algorithm achieves better performance than that of some existing decoding algorithms with the same code length. Yingxian Zhang, Xiaofei Pan, Kegang Pan, Zhan Ye, and Chao Gong Copyright © 2014 Yingxian Zhang et al. All rights reserved. Recent Advances in Complex Networks Theories with Applications Wed, 23 Jul 2014 06:30:59 +0000 http://www.hindawi.com/journals/tswj/2014/504923/ Hamid Reza Karimi, Wei Zhang, Xuebo Yang, and Zhandong Yu Copyright © 2014 Hamid Reza Karimi et al. All rights reserved. An Energy Efficient Simultaneous-Node Repositioning Algorithm for Mobile Sensor Networks Wed, 23 Jul 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/785305/ Recently, wireless sensor network (WSN) applications have seen an increase in interest. In search and rescue, battlefield reconnaissance, and some other such applications, so that a survey of the area of interest can be made collectively, a set of mobile nodes is deployed. Keeping the network nodes connected is vital for WSNs to be effective. The provision of connectivity can be made at the time of startup and can be maintained by carefully coordinating the nodes when they move. However, if a node suddenly fails, the network could be partitioned to cause communication problems. Recently, several methods that use the relocation of nodes for connectivity restoration have been proposed. However, these methods have the tendency to not consider the potential coverage loss in some locations. This paper addresses the concerns of both connectivity and coverage in an integrated way so that this gap can be filled. A novel algorithm for simultaneous-node repositioning is introduced. In this approach, each neighbour of the failed node, one by one, moves in for a certain amount of time to take the place of the failed node, after which it returns to its original location in the network. The effectiveness of this algorithm has been verified by the simulation results. Muhammad Amir Khan, Halabi Hasbullah, Babar Nazir, and Imran Ali Khan Copyright © 2014 Muhammad Amir Khan et al. All rights reserved. A Fuzzy-Decision Based Approach for Composite Event Detection in Wireless Sensor Networks Mon, 21 Jul 2014 10:28:13 +0000 http://www.hindawi.com/journals/tswj/2014/816892/ The event detection is one of the fundamental researches in wireless sensor networks (WSNs). Due to the consideration of various properties that reflect events status, the Composite event is more consistent with the objective world. Thus, the research of the Composite event becomes more realistic. In this paper, we analyze the characteristics of the Composite event; then we propose a criterion to determine the area of the Composite event and put forward a dominating set based network topology construction algorithm under random deployment. For the unreliability of partial data in detection process and fuzziness of the event definitions in nature, we propose a cluster-based two-dimensional τ-GAS algorithm and fuzzy-decision based composite event decision mechanism. In the case that the sensory data of most nodes are normal, the two-dimensional τ-GAS algorithm can filter the fault node data effectively and reduce the influence of erroneous data on the event determination. The Composite event judgment mechanism which is based on fuzzy-decision holds the superiority of the fuzzy-logic based algorithm; moreover, it does not need the support of a huge rule base and its computational complexity is small. Compared to CollECT algorithm and CDS algorithm, this algorithm improves the detection accuracy and reduces the traffic. Shukui Zhang, Hao Chen, Qiaoming Zhu, and Juncheng Jia Copyright © 2014 Shukui Zhang et al. All rights reserved. Low-Cost Dielectric Substrate for Designing Low Profile Multiband Monopole Microstrip Antenna Sun, 20 Jul 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/183741/ This paper proposes a small sized, low-cost multiband monopole antenna which can cover the WiMAX bands and C-band. The proposed antenna of 20 × 20 mm2 radiating patch is printed on cost effective 1.6 mm thick fiberglass polymer resin dielectric material substrate and fed by 4 mm long microstrip line. The finite element method based, full wave electromagnetic simulator HFSS is efficiently utilized for designing and analyzing the proposed antenna and the antenna parameters are measured in a standard far-field anechoic chamber. The experimental results show that the prototype of the antenna has achieved operating bandwidths (voltage stand wave ratio (VSWR) less than 2) 360 MHz (2.53–2.89 GHz) and 440 MHz (3.47–3.91 GHz) for WiMAX and 1550 MHz (6.28–7.83 GHz) for C-band. The simulated and measured results for VSWR, radiation patterns, and gain are well matched. Nearly omnidirectional radiation patterns are achieved and the peak gains are of 3.62 dBi, 3.67 dBi, and 5.7 dBi at 2.66 GHz, 3.65 GHz, and 6.58 GHz, respectively. M. R. Ahsan, M. T. Islam, M. Habib Ullah, H. Arshad, and M. F. Mansor Copyright © 2014 M. R. Ahsan et al. All rights reserved. Protection of HEVC Video Delivery in Vehicular Networks with RaptorQ Codes Thu, 17 Jul 2014 11:47:15 +0000 http://www.hindawi.com/journals/tswj/2014/619379/ With future vehicles equipped with processing capability, storage, and communications, vehicular networks will become a reality. A vast number of applications will arise that will make use of this connectivity. Some of them will be based on video streaming. In this paper we focus on HEVC video coding standard streaming in vehicular networks and how it deals with packet losses with the aid of RaptorQ, a Forward Error Correction scheme. As vehicular networks are packet loss prone networks, protection mechanisms are necessary if we want to guarantee a minimum level of quality of experience to the final user. We have run simulations to evaluate which configurations fit better in this type of scenarios. Pablo Piñol, Miguel Martínez-Rach, Otoniel López, and Manuel Pérez Malumbres Copyright © 2014 Pablo Piñol et al. All rights reserved. An Action-Based Fine-Grained Access Control Mechanism for Structured Documents and Its Application Thu, 17 Jul 2014 08:53:02 +0000 http://www.hindawi.com/journals/tswj/2014/232708/ This paper presents an action-based fine-grained access control mechanism for structured documents. Firstly, we define a describing model for structured documents and analyze the application scenarios. The describing model could support the permission management on chapters, pages, sections, words, and pictures of structured documents. Secondly, based on the action-based access control (ABAC) model, we propose a fine-grained control protocol for structured documents by introducing temporal state and environmental state. The protocol covering different stages from document creation, to permission specification and usage control are given by using the Z-notation. Finally, we give the implementation of our mechanism and make the comparisons between the existing methods and our mechanism. The result shows that our mechanism could provide the better solution of fine-grained access control for structured documents in complicated networks. Moreover, it is more flexible and practical. Mang Su, Fenghua Li, Zhi Tang, Yinyan Yu, and Bo Zhou Copyright © 2014 Mang Su et al. All rights reserved. Quality of Protection Evaluation of Security Mechanisms Thu, 17 Jul 2014 07:51:50 +0000 http://www.hindawi.com/journals/tswj/2014/725279/ Recent research indicates that during the design of teleinformatic system the tradeoff between the systems performance and the system protection should be made. The traditional approach assumes that the best way is to apply the strongest possible security measures. Unfortunately, the overestimation of security measures can lead to the unreasonable increase of system load. This is especially important in multimedia systems where the performance has critical character. In many cases determination of the required level of protection and adjustment of some security measures to these requirements increase system efficiency. Such an approach is achieved by means of the quality of protection models where the security measures are evaluated according to their influence on the system security. In the paper, we propose a model for QoP evaluation of security mechanisms. Owing to this model, one can quantify the influence of particular security mechanisms on ensuring security attributes. The methodology of our model preparation is described and based on it the case study analysis is presented. We support our method by the tool where the models can be defined and QoP evaluation can be performed. Finally, we have modelled TLS cryptographic protocol and presented the QoP security mechanisms evaluation for the selected versions of this protocol. Bogdan Ksiezopolski, Tomasz Zurek, and Michail Mokkas Copyright © 2014 Bogdan Ksiezopolski et al. All rights reserved. A Secure 3-Way Routing Protocols for Intermittently Connected Mobile Ad Hoc Networks Thu, 17 Jul 2014 07:28:18 +0000 http://www.hindawi.com/journals/tswj/2014/865071/ The mobile ad hoc network may be partially connected or it may be disconnected in nature and these forms of networks are termed intermittently connected mobile ad hoc network (ICMANET). The routing in such disconnected network is commonly an arduous task. Many routing protocols have been proposed for routing in ICMANET since decades. The routing techniques in existence for ICMANET are, namely, flooding, epidemic, probabilistic, copy case, spray and wait, and so forth. These techniques achieve an effective routing with minimum latency, higher delivery ratio, lesser overhead, and so forth. Though these techniques generate effective results, in this paper, we propose novel routing algorithms grounded on agent and cryptographic techniques, namely, location dissemination service (LoDiS) routing with agent AES, A-LoDiS with agent AES routing, and B-LoDiS with agent AES routing, ensuring optimal results with respect to various network routing parameters. The algorithm along with efficient routing ensures higher degree of security. The security level is cited testing with respect to possibility of malicious nodes into the network. This paper also aids, with the comparative results of proposed algorithms, for secure routing in ICMANET. Ramesh Sekaran and Ganesh Kumar Parasuraman Copyright © 2014 Ramesh Sekaran and Ganesh Kumar Parasuraman. All rights reserved. Design and Performance Evaluation of a Distributed OFDMA-Based MAC Protocol for MANETs Wed, 16 Jul 2014 12:19:12 +0000 http://www.hindawi.com/journals/tswj/2014/708798/ In this paper, we propose a distributed MAC protocol for OFDMA-based wireless mobile ad hoc multihop networks, in which the resource reservation and data transmission procedures are operated in a distributed manner. A frame format is designed considering the characteristics of OFDMA that each node can transmit or receive data to or from multiple nodes simultaneously. Under this frame structure, we propose a distributed resource management method including network state estimation and resource reservation processes. We categorize five types of logical errors according to their root causes and show that two of the logical errors are inevitable while three of them are avoided under the proposed distributed MAC protocol. In addition, we provide a systematic method to determine the advertisement period of each node by presenting a clear relation between the accuracy of estimated network states and the signaling overhead. We evaluate the performance of the proposed protocol in respect of the reservation success rate and the success rate of data transmission. Since our method focuses on avoiding logical errors, it could be easily placed on top of the other resource allocation methods focusing on the physical layer issues of the resource management problem and interworked with them. Jaesung Park, Jiyoung Chung, Hyungyu Lee, and Jung-Ryun Lee Copyright © 2014 Jaesung Park et al. All rights reserved. Malware Analysis Using Visualized Image Matrices Wed, 16 Jul 2014 09:26:18 +0000 http://www.hindawi.com/journals/tswj/2014/132713/ This paper proposes a novel malware visual analysis method that contains not only a visualization method to convert binary files into images, but also a similarity calculation method between these images. The proposed method generates RGB-colored pixels on image matrices using the opcode sequences extracted from malware samples and calculates the similarities for the image matrices. Particularly, our proposed methods are available for packed malware samples by applying them to the execution traces extracted through dynamic analysis. When the images are generated, we can reduce the overheads by extracting the opcode sequences only from the blocks that include the instructions related to staple behaviors such as functions and application programming interface (API) calls. In addition, we propose a technique that generates a representative image for each malware family in order to reduce the number of comparisons for the classification of unknown samples and the colored pixel information in the image matrices is used to calculate the similarities between the images. Our experimental results show that the image matrices of malware can effectively be used to classify malware families both statically and dynamically with accuracy of 0.9896 and 0.9732, respectively. KyoungSoo Han, BooJoong Kang, and Eul Gyu Im Copyright © 2014 KyoungSoo Han et al. All rights reserved. A New Graph Drawing Scheme for Social Network Wed, 16 Jul 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/930314/ With the development of social networks, people have started to use social network tools to record their life and work more and more frequently. How to analyze social networks to explore potential characteristics and trend of social events has been a hot research topic. In order to analyze it effectively, a kind of techniques called information visualization is employed to extract the potential information from the large scale of social network data and present the information briefly as visualized graphs. In the process of information visualization, graph drawing is a crucial part. In this paper, we study the graph layout algorithms and propose a new graph drawing scheme combining multilevel and single-level drawing approaches, including the graph division method based on communities and refining approach based on partitioning strategy. Besides, we compare the effectiveness of our scheme and FM3 in experiments. The experiment results show that our scheme can achieve a clearer diagram and effectively extract the community structure of the social network to be applied to drawing schemes. Eric Ke Wang and Futai Zou Copyright © 2014 Eric Ke Wang and Futai Zou. All rights reserved. Video Texture Synthesis Based on Flow-Like Stylization Painting Tue, 15 Jul 2014 10:52:18 +0000 http://www.hindawi.com/journals/tswj/2014/689496/ The paper presents an NP-video rendering system based on natural phenomena. It provides a simple nonphotorealistic video synthesis system in which user can obtain a flow-like stylization painting and infinite video scene. Firstly, based on anisotropic Kuwahara filtering in conjunction with line integral convolution, the phenomena video scene can be rendered to flow-like stylization painting. Secondly, the methods of frame division, patches synthesis, will be used to synthesize infinite playing video. According to selection examples from different natural video texture, our system can generate stylized of flow-like and infinite video scenes. The visual discontinuities between neighbor frames are decreased, and we also preserve feature and details of frames. This rendering system is easy and simple to implement. Qian Wenhua, Xu Dan, Yue Kun, and Guan Zheng Copyright © 2014 Qian Wenhua et al. All rights reserved. Design and Realization of a Planar Ultrawideband Antenna with Notch Band at 3.5 GHz Tue, 15 Jul 2014 10:07:25 +0000 http://www.hindawi.com/journals/tswj/2014/563830/ A small antenna with single notch band at 3.5 GHz is designed for ultrawideband (UWB) communication applications. The fabricated antenna comprises a radiating monopole element and a perfectly conducting ground plane with a wide slot. To achieve a notch band at 3.5 GHz, a parasitic element has been inserted in the same plane of the substrate along with the radiating patch. Experimental results shows that, by properly adjusting the position of the parasitic element, the designed antenna can achieve an ultrawide operating band of 3.04 to 11 GHz with a notched band operating at 3.31–3.84 GHz. Moreover, the proposed antenna achieved a good gain except at the notched band and exhibits symmetric radiation patterns throughout the operating band. The prototype of the proposed antenna possesses a very compact size and uses simple structures to attain the stop band characteristic with an aim to lessen the interference between UWB and worldwide interoperability for microwave access (WiMAX) band. Rezaul Azim, Mohammad Tariqul Islam, Norbahiah Misran, Baharudin Yatim, and Haslina Arshad Copyright © 2014 Rezaul Azim et al. All rights reserved. Modeling the Propagation of Mobile Phone Virus under Complex Network Tue, 15 Jul 2014 07:27:14 +0000 http://www.hindawi.com/journals/tswj/2014/207457/ Mobile phone virus is a rogue program written to propagate from one phone to another, which can take control of a mobile device by exploiting its vulnerabilities. In this paper the propagation model of mobile phone virus is tackled to understand how particular factors can affect its propagation and design effective containment strategies to suppress mobile phone virus. Two different propagation models of mobile phone viruses under the complex network are proposed in this paper. One is intended to describe the propagation of user-tricking virus, and the other is to describe the propagation of the vulnerability-exploiting virus. Based on the traditional epidemic models, the characteristics of mobile phone viruses and the network topology structure are incorporated into our models. A detailed analysis is conducted to analyze the propagation models. Through analysis, the stable infection-free equilibrium point and the stability condition are derived. Finally, considering the network topology, the numerical and simulation experiments are carried out. Results indicate that both models are correct and suitable for describing the spread of two different mobile phone viruses, respectively. Wei Yang, Xi-liang Wei, Hao Guo, Gang An, Lei Guo, and Yu Yao Copyright © 2014 Wei Yang et al. All rights reserved. Reliable Multihop Broadcast Protocol with a Low-Overhead Link Quality Assessment for ITS Based on VANETs in Highway Scenarios Tue, 15 Jul 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/359636/ Vehicular ad hoc networks (VANETs) have been identified as a key technology to enable intelligent transport systems (ITS), which are aimed to radically improve the safety, comfort, and greenness of the vehicles in the road. However, in order to fully exploit VANETs potential, several issues must be addressed. Because of the high dynamic of VANETs and the impairments in the wireless channel, one key issue arising when working with VANETs is the multihop dissemination of broadcast packets for safety and infotainment applications. In this paper a reliable low-overhead multihop broadcast (RLMB) protocol is proposed to address the well-known broadcast storm problem. The proposed RLMB takes advantage of the hello messages exchanged between the vehicles and it processes such information to intelligently select a relay set and reduce the redundant broadcast. Additionally, to reduce the hello messages rate dependency, RLMB uses a point-to-zone link evaluation approach. RLMB performance is compared with one of the leading multihop broadcast protocols existing to date. Performance metrics show that our RLMB solution outperforms the leading protocol in terms of important metrics such as packet dissemination ratio, overhead, and delay. Alejandro Galaviz-Mosqueda, Salvador Villarreal-Reyes, Hiram Galeana-Zapién, Javier Rubio-Loyola, and David H. Covarrubias-Rosales Copyright © 2014 Alejandro Galaviz-Mosqueda et al. All rights reserved. New Ray Tracing Method to Investigate the Various Effects on Wave Propagation in Medical Scenario: An Application of Wireless Body Area Network Mon, 14 Jul 2014 11:26:43 +0000 http://www.hindawi.com/journals/tswj/2014/306270/ The advent of technology with the increasing use of wireless network has led to the development of Wireless Body Area Network (WBAN) to continuously monitor the change of physiological data in a cost efficient manner. As numerous researches on wave propagation characterization have been done in intrabody communication, this study has given emphasis on the wave propagation characterization between the control units (CUs) and wireless access point (AP) in a hospital scenario. Ray tracing is a tool to predict the rays to characterize the wave propagation. It takes huge simulation time, especially when multiple transmitters are involved to transmit physiological data in a realistic hospital environment. Therefore, this study has developed an accelerated ray tracing method based on the nearest neighbor cell and prior knowledge of intersection techniques. Beside this, Red-Black tree is used to store and provide a faster retrieval mechanism of objects in the hospital environment. To prove the superiority, detailed complexity analysis and calculations of reflection and transmission coefficients are also presented in this paper. The results show that the proposed method is about 1.51, 2.1, and 2.9 times faster than the Object Distribution Technique (ODT), Space Volumetric Partitioning (SVP), and Angular Z-Buffer (AZB) methods, respectively. To show the various effects on received power in 60 GHz frequency, few comparisons are made and it is found that on average −9.44 dBm, −8.23 dBm, and −9.27 dBm received power attenuations should be considered when human, AP, and CU move in a given hospital scenario. M. J. Islam, A. W. Reza, A. S. M. Z. Kausar, and H. Ramiah Copyright © 2014 M. J. Islam et al. All rights reserved. Fuzzy-Based Trust Prediction Model for Routing in WSNs Mon, 14 Jul 2014 07:08:05 +0000 http://www.hindawi.com/journals/tswj/2014/480202/ The cooperative nature of multihop wireless sensor networks (WSNs) makes it vulnerable to varied types of attacks. The sensitive application environments and resource constraints of WSNs mandate the requirement of lightweight security scheme. The earlier security solutions were based on historical behavior of neighbor but the security can be enhanced by predicting the future behavior of the nodes in the network. In this paper, we proposed a fuzzy-based trust prediction model for routing (FTPR) in WSNs with minimal overhead in regard to memory and energy consumption. FTPR incorporates a trust prediction model that predicts the future behavior of the neighbor based on the historical behavior, fluctuations in trust value over a period of time, and recommendation inconsistency. In order to reduce the control overhead, FTPR received recommendations from a subset of neighbors who had maximum number of interactions with the requestor. Theoretical analysis and simulation results of FTPR protocol demonstrate higher packet delivery ratio, higher network lifetime, lower end-to-end delay, and lower memory and energy consumption than the traditional and existing trust-based routing schemes. X. Anita, M. A. Bhagyaveni, and J. Martin Leo Manickam Copyright © 2014 X. Anita et al. All rights reserved. A Novel Modulation Classification Approach Using Gabor Filter Network Mon, 14 Jul 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/643671/ A Gabor filter network based approach is used for feature extraction and classification of digital modulated signals by adaptively tuning the parameters of Gabor filter network. Modulation classification of digitally modulated signals is done under the influence of additive white Gaussian noise (AWGN). The modulations considered for the classification purpose are PSK 2 to 64, FSK 2 to 64, and QAM 4 to 64. The Gabor filter network uses the network structure of two layers; the first layer which is input layer constitutes the adaptive feature extraction part and the second layer constitutes the signal classification part. The Gabor atom parameters are tuned using Delta rule and updating of weights of Gabor filter using least mean square (LMS) algorithm. The simulation results show that proposed novel modulation classification algorithm has high classification accuracy at low signal to noise ratio (SNR) on AWGN channel. Sajjad Ahmed Ghauri, Ijaz Mansoor Qureshi, Tanveer Ahmed Cheema, and Aqdas Naveed Malik Copyright © 2014 Sajjad Ahmed Ghauri et al. All rights reserved. IDMA-Based MAC Protocol for Satellite Networks with Consideration on Channel Quality Sun, 13 Jul 2014 11:40:36 +0000 http://www.hindawi.com/journals/tswj/2014/181734/ In order to overcome the shortcomings of existing medium access control (MAC) protocols based on TDMA or CDMA in satellite networks, interleave division multiple access (IDMA) technique is introduced into satellite communication networks. Therefore, a novel wide-band IDMA MAC protocol based on channel quality is proposed in this paper, consisting of a dynamic power allocation algorithm, a rate adaptation algorithm, and a call admission control (CAC) scheme. Firstly, the power allocation algorithm combining the technique of IDMA SINR-evolution and channel quality prediction is developed to guarantee high power efficiency even in terrible channel conditions. Secondly, the effective rate adaptation algorithm, based on accurate channel information per timeslot and by the means of rate degradation, can be realized. What is more, based on channel quality prediction, the CAC scheme, combining the new power allocation algorithm, rate scheduling, and buffering strategies together, is proposed for the emerging IDMA systems, which can support a variety of traffic types, and offering quality of service (QoS) requirements corresponding to different priority levels. Simulation results show that the new wide-band IDMA MAC protocol can make accurate estimation of available resource considering the effect of multiuser detection (MUD) and QoS requirements of multimedia traffic, leading to low outage probability as well as high overall system throughput. Gongliang Liu, Xinrui Fang, and Wenjing Kang Copyright © 2014 Gongliang Liu et al. All rights reserved. A Mobile Anchor Assisted Localization Algorithm Based on Regular Hexagon in Wireless Sensor Networks Sun, 13 Jul 2014 07:17:34 +0000 http://www.hindawi.com/journals/tswj/2014/219371/ Localization is one of the key technologies in wireless sensor networks (WSNs), since it provides fundamental support for many location-aware protocols and applications. Constraints of cost and power consumption make it infeasible to equip each sensor node in the network with a global position system (GPS) unit, especially for large-scale WSNs. A promising method to localize unknown nodes is to use several mobile anchors which are equipped with GPS units moving among unknown nodes and periodically broadcasting their current locations to help nearby unknown nodes with localization. This paper proposes a mobile anchor assisted localization algorithm based on regular hexagon (MAALRH) in two-dimensional WSNs, which can cover the whole monitoring area with a boundary compensation method. Unknown nodes calculate their positions by using trilateration. We compare the MAALRH with HILBERT, CIRCLES, and S-CURVES algorithms in terms of localization ratio, localization accuracy, and path length. Simulations show that the MAALRH can achieve high localization ratio and localization accuracy when the communication range is not smaller than the trajectory resolution. Guangjie Han, Chenyu Zhang, Jaime Lloret, Lei Shu, and Joel J. P. C. Rodrigues Copyright © 2014 Guangjie Han et al. All rights reserved. Vehicle Density Based Forwarding Protocol for Safety Message Broadcast in VANET Thu, 10 Jul 2014 08:18:13 +0000 http://www.hindawi.com/journals/tswj/2014/584164/ In vehicular ad hoc networks (VANETs), the medium access control (MAC) protocol is of great importance to provide time-critical safety applications. Contemporary multihop broadcast protocols in VANETs usually choose the farthest node in broadcast range as the forwarder to reduce the number of forwarding hops. However, in this paper, we demonstrate that the farthest forwarder may experience large contention delay in case of high vehicle density. We propose an IEEE 802.11-based multihop broadcast protocol VDF to address the issue of emergency message dissemination. To achieve the tradeoff between contention delay and forwarding hops, VDF adaptably chooses the forwarder according to the vehicle density. Simulation results show that, due to its ability to decrease the transmission collisions, the proposed protocol can provide significantly lower broadcast delay. Jiawei Huang, Yi Huang, and Jianxin Wang Copyright © 2014 Jiawei Huang et al. All rights reserved. Exploring a QoS Driven Scheduling Approach for Peer-to-Peer Live Streaming Systems with Network Coding Thu, 10 Jul 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/513861/ Most large-scale peer-to-peer (P2P) live streaming systems use mesh to organize peers and leverage pull scheduling to transmit packets for providing robustness in dynamic environment. The pull scheduling brings large packet delay. Network coding makes the push scheduling feasible in mesh P2P live streaming and improves the efficiency. However, it may also introduce some extra delays and coding computational overhead. To improve the packet delay, streaming quality, and coding overhead, in this paper are as follows. we propose a QoS driven push scheduling approach. The main contributions of this paper are: (i) We introduce a new network coding method to increase the content diversity and reduce the complexity of scheduling; (ii) we formulate the push scheduling as an optimization problem and transform it to a min-cost flow problem for solving it in polynomial time; (iii) we propose a push scheduling algorithm to reduce the coding overhead and do extensive experiments to validate the effectiveness of our approach. Compared with previous approaches, the simulation results demonstrate that packet delay, continuity index, and coding ratio of our system can be significantly improved, especially in dynamic environments. Laizhong Cui, Nan Lu, and Fu Chen Copyright © 2014 Laizhong Cui et al. All rights reserved. SER Performance of Enhanced Spatial Multiplexing Codes with ZF/MRC Receiver in Time-Varying Rayleigh Fading Channels Thu, 10 Jul 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/537272/ We propose enhanced spatial multiplexing codes (E-SMCs) to enable various encoding rates. The symbol error rate (SER) performance of the E-SMC is investigated when zero-forcing (ZF) and maximal-ratio combining (MRC) techniques are used at a receiver. The proposed E-SMC allows a transmitted symbol to be repeated over time to achieve further diversity gain at the cost of the encoding rate. With the spatial correlation between transmit antennas, SER equations for -ary QAM and PSK constellations are derived by using a moment generating function (MGF) approximation of a signal-to-noise ratio (SNR), based on the assumption of independent zero-forced SNRs. Analytic and simulated results are compared for time-varying and spatially correlated Rayleigh fading channels that are modelled as first-order Markovian channels. Furthermore, we can find an optimal block length for the E-SMC that meets a required SER. In-Ho Lee Copyright © 2014 In-Ho Lee. All rights reserved. A Spread Willingness Computing-Based Information Dissemination Model Thu, 10 Jul 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/680421/ This paper constructs a kind of spread willingness computing based on information dissemination model for social network. The model takes into account the impact of node degree and dissemination mechanism, combined with the complex network theory and dynamics of infectious diseases, and further establishes the dynamical evolution equations. Equations characterize the evolutionary relationship between different types of nodes with time. The spread willingness computing contains three factors which have impact on user’s spread behavior: strength of the relationship between the nodes, views identity, and frequency of contact. Simulation results show that different degrees of nodes show the same trend in the network, and even if the degree of node is very small, there is likelihood of a large area of information dissemination. The weaker the relationship between nodes, the higher probability of views selection and the higher the frequency of contact with information so that information spreads rapidly and leads to a wide range of dissemination. As the dissemination probability and immune probability change, the speed of information dissemination is also changing accordingly. The studies meet social networking features and can help to master the behavior of users and understand and analyze characteristics of information dissemination in social network. Haojing Huang, Zhiming Cui, and Shukui Zhang Copyright © 2014 Haojing Huang et al. All rights reserved. Towards Dynamic Remote Data Auditing in Computational Clouds Wed, 09 Jul 2014 14:28:46 +0000 http://www.hindawi.com/journals/tswj/2014/269357/ Cloud computing is a significant shift of computational paradigm where computing as a utility and storing data remotely have a great potential. Enterprise and businesses are now more interested in outsourcing their data to the cloud to lessen the burden of local data storage and maintenance. However, the outsourced data and the computation outcomes are not continuously trustworthy due to the lack of control and physical possession of the data owners. To better streamline this issue, researchers have now focused on designing remote data auditing (RDA) techniques. The majority of these techniques, however, are only applicable for static archive data and are not subject to audit the dynamically updated outsourced data. We propose an effectual RDA technique based on algebraic signature properties for cloud storage system and also present a new data structure capable of efficiently supporting dynamic data operations like append, insert, modify, and delete. Moreover, this data structure empowers our method to be applicable for large-scale data with minimum computation cost. The comparative analysis with the state-of-the-art RDA schemes shows that the proposed scheme is secure and highly efficient in terms of the computation and communication overhead on the auditor and server. Mehdi Sookhak, Adnan Akhunzada, Abdullah Gani, Muhammad Khurram Khan, and Nor Badrul Anuar Copyright © 2014 Mehdi Sookhak et al. All rights reserved. Constructing Topic Models of Internet of Things for Information Processing Wed, 09 Jul 2014 12:07:57 +0000 http://www.hindawi.com/journals/tswj/2014/675234/ Internet of Things (IoT) is regarded as a remarkable development of the modern information technology. There is abundant digital products data on the IoT, linking with multiple types of objects/entities. Those associated entities carry rich information and usually in the form of query records. Therefore, constructing high quality topic hierarchies that can capture the term distribution of each product record enables us to better understand users’ search intent and benefits tasks such as taxonomy construction, recommendation systems, and other communications solutions for the future IoT. In this paper, we propose a novel record entity topic model (RETM) for IoT environment that is associated with a set of entities and records and a Gibbs sampling-based algorithm is proposed to learn the model. We conduct extensive experiments on real-world datasets and compare our approach with existing methods to demonstrate the advantage of our approach. Jie Xin, Zhiming Cui, Shukui Zhang, Tianxu He, Chunhua Li, and Haojing Huang Copyright © 2014 Jie Xin et al. All rights reserved. Reconfigurable Ring Filter with Controllable Frequency Response Tue, 08 Jul 2014 11:09:44 +0000 http://www.hindawi.com/journals/tswj/2014/671369/ Reconfigurable ring filter based on single-side-access ring topology is presented. Using capacitive tuning elements, the electrical length of the ring can be manipulated to shift the nominal center frequency to a desired position. A synthesis is developed to determine the values of the capacitive elements. To show the advantage of the synthesis, it is applied to the reconfigurable filter design using RF lumped capacitors. The concept is further explored by introducing varactor-diodes to continuously tune the center frequency of the ring filter. For demonstration, two prototypes of reconfigurable ring filters are realized using microstrip technology, simulated, and measured to validate the proposed concept. The reconfigured filter using lumped elements is successfully reconfigured from 2 GHz to 984.4 MHz and miniaturized by 71% compared to the filter directly designed at the same reconfigured frequency, while, for the filter using varactor-diodes, the frequency is chosen from 1.10 GHz to 1.38 GHz spreading over 280 MHz frequency range. Both designs are found to be compact with acceptable insertion loss and high selectivity. Norfishah Ab Wahab, Mohd Khairul Mohd Salleh, Zuhani Ismail Khan, and Nur Emileen Abd Rashid Copyright © 2014 Norfishah Ab Wahab et al. All rights reserved. Combining Digital Watermarking and Fingerprinting Techniques to Identify Copyrights for Color Images Tue, 08 Jul 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/454867/ This paper presents a copyright identification scheme for color images that takes advantage of the complementary nature of watermarking and fingerprinting. It utilizes an authentication logo and the extracted features of the host image to generate a fingerprint, which is then stored in a database and also embedded in the host image to produce a watermarked image. When a dispute over the copyright of a suspect image occurs, the image is first processed by watermarking. If the watermark can be retrieved from the suspect image, the copyright can then be confirmed; otherwise, the watermark then serves as the fingerprint and is processed by fingerprinting. If a match in the fingerprint database is found, then the suspect image will be considered a duplicated one. Because the proposed scheme utilizes both watermarking and fingerprinting, it is more robust than those that only adopt watermarking, and it can also obtain the preliminary result more quickly than those that only utilize fingerprinting. The experimental results show that when the watermarked image suffers slight attacks, watermarking alone is enough to identify the copyright. The results also show that when the watermarked image suffers heavy attacks that render watermarking incompetent, fingerprinting can successfully identify the copyright, hence demonstrating the effectiveness of the proposed scheme. Shang-Lin Hsieh, Chun-Che Chen, and Wen-Shan Shen Copyright © 2014 Shang-Lin Hsieh et al. All rights reserved. A Comprehensive Review on Adaptability of Network Forensics Frameworks for Mobile Cloud Computing Sun, 06 Jul 2014 10:43:50 +0000 http://www.hindawi.com/journals/tswj/2014/547062/ Network forensics enables investigation and identification of network attacks through the retrieved digital content. The proliferation of smartphones and the cost-effective universal data access through cloud has made Mobile Cloud Computing (MCC) a congenital target for network attacks. However, confines in carrying out forensics in MCC is interrelated with the autonomous cloud hosting companies and their policies for restricted access to the digital content in the back-end cloud platforms. It implies that existing Network Forensic Frameworks (NFFs) have limited impact in the MCC paradigm. To this end, we qualitatively analyze the adaptability of existing NFFs when applied to the MCC. Explicitly, the fundamental mechanisms of NFFs are highlighted and then analyzed using the most relevant parameters. A classification is proposed to help understand the anatomy of existing NFFs. Subsequently, a comparison is given that explores the functional similarities and deviations among NFFs. The paper concludes by discussing research challenges for progressive network forensics in MCC. Suleman Khan, Muhammad Shiraz, Ainuddin Wahid Abdul Wahab, Abdullah Gani, Qi Han, and Zulkanain Bin Abdul Rahman Copyright © 2014 Suleman Khan et al. All rights reserved. A Model Based Security Testing Method for Protocol Implementation Sun, 06 Jul 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/632154/ The security of protocol implementation is important and hard to be verified. Since the penetration testing is usually based on the experience of the security tester and the specific protocol specifications, a formal and automatic verification method is always required. In this paper, we propose an extended model of IOLTS to describe the legal roles and intruders of security protocol implementations, and then combine them together to generate the suitable test cases to verify the security of protocol implementation. Yu Long Fu and Xiao Long Xin Copyright © 2014 Yu Long Fu and Xiao Long Xin. All rights reserved. Extraction of Multilayered Social Networks from Activity Data Wed, 02 Jul 2014 08:22:31 +0000 http://www.hindawi.com/journals/tswj/2014/359868/ The data gathered in all kinds of web-based systems, which enable users to interact with each other, provides an opportunity to extract social networks that consist of people and relationships between them. The emerging structures are very complex due to the number and type of discovered connections. In web-based systems, the characteristic element of each interaction between users is that there is always an object that serves as a communication medium. This can be, for example, an e-mail sent from one user to another or post at the forum authored by one user and commented on by others. Based on these objects and activities that users perform towards them, different kinds of relationships can be identified and extracted. Additional challenge arises from the fact that hierarchies can exist between objects; for example, a forum consists of one or more groups of topics, and each of them contains topics that finally include posts. In this paper, we propose a new method for creation of multilayered social network based on the data about users activities towards different types of objects between which the hierarchy exists. Due to the flattening, preprocessing procedure of new layers and new relationships in the multilayered social network can be identified and analysed. Katarzyna Musial, Piotr Bródka, Przemysław Kazienko, and Jarosław Gaworecki Copyright © 2014 Katarzyna Musial et al. All rights reserved. A Game-Theoretic Response Strategy for Coordinator Attack in Wireless Sensor Networks Tue, 01 Jul 2014 12:33:39 +0000 http://www.hindawi.com/journals/tswj/2014/950618/ The coordinator is a specific node that controls the whole network and has a significant impact on the performance in cooperative multihop ZigBee wireless sensor networks (ZWSNs). However, the malicious node attacks coordinator nodes in an effort to waste the resources and disrupt the operation of the network. Attacking leads to a failure of one round of communication between the source nodes and destination nodes. Coordinator selection is a technique that can considerably defend against attack and reduce the data delivery delay, and increase network performance of cooperative communications. In this paper, we propose an adaptive coordinator selection algorithm using game and fuzzy logic aiming at both minimizing the average number of hops and maximizing network lifetime. The proposed game model consists of two interrelated formulations: a stochastic game for dynamic defense and a best response policy using evolutionary game formulation for coordinator selection. The stable equilibrium best policy to response defense is obtained from this game model. It is shown that the proposed scheme can improve reliability and save energy during the network lifetime with respect to security. Jianhua Liu, Guangxue Yue, Shigen Shen, Huiliang Shang, and Hongjie Li Copyright © 2014 Jianhua Liu et al. All rights reserved. Calculating the Number of Cluster Heads Based on the Rate-Distortion Function in Wireless Sensor Networks Tue, 01 Jul 2014 09:52:33 +0000 http://www.hindawi.com/journals/tswj/2014/602875/ Due to limited resources in wireless sensor nodes, energy efficiency is considered as one of the primary constraints in the design of the topology of wireless sensor networks (WSNs). Since data that are collected by wireless sensor nodes exhibit the characteristics of temporal association, data fusion has also become a very important means of reducing network traffic as well as eliminating data redundancy as far as data transmission is concerned. Another reason for data fusion is that, in many applications, only some of the data that are collected can meet the requirements of the sink node. In this paper, we propose a method to calculate the number of cluster heads or data aggregators during data fusion based on the rate-distortion function. In our discussion, we will first establish an energy consumption model and then describe a method for calculating the number of cluster heads from the point of view of reducing energy consumption. We will also show through theoretical analysis and experimentation that the network topology design based on the rate-distortion function is indeed more energy-efficient. Mingxin Yang, Jingsha He, and Yuqiang Zhang Copyright © 2014 Mingxin Yang et al. All rights reserved. Comprehensive Control of Networked Control Systems with Multistep Delay Tue, 01 Jul 2014 07:52:39 +0000 http://www.hindawi.com/journals/tswj/2014/814245/ In networked control systems with multi-step delay, long time-delay causes vacant sampling and controller design difficulty. In order to solve the above problems, comprehensive control methods are proposed in this paper. Time-delay compensation control and linear-quadratic-Guassian (LQG) optimal control are adopted and the systems switch different controllers between two different states. LQG optimal controller is used with probability in normal state, which is shown to render the systems mean square exponentially stable. Time-delay compensation controller is used with probability in abnormal state to compensate vacant sampling and long time-delay. In addition, a buffer window is established at the actuator of the systems to store some history control inputs which are used to estimate the control state of present sampling period under the vacant sampling cases. The comprehensive control methods simplify control design which is easier to be implemented in engineering. The performance of the systems is also improved. Simulation results verify the validity of the proposed theory. Jie Jiang and Changlin Ma Copyright © 2014 Jie Jiang and Changlin Ma. All rights reserved. Optimization of Self-Directed Target Coverage in Wireless Multimedia Sensor Network Mon, 30 Jun 2014 10:35:28 +0000 http://www.hindawi.com/journals/tswj/2014/416218/ Video and image sensors in wireless multimedia sensor networks (WMSNs) have directed view and limited sensing angle. So the methods to solve target coverage problem for traditional sensor networks, which use circle sensing model, are not suitable for WMSNs. Based on the FoV (field of view) sensing model and FoV disk model proposed, how expected multimedia sensor covers the target is defined by the deflection angle between target and the sensor’s current orientation and the distance between target and the sensor. Then target coverage optimization algorithms based on expected coverage value are presented for single-sensor single-target, multisensor single-target, and single-sensor multitargets problems distinguishingly. Selecting the orientation that sensor rotated to cover every target falling in the FoV disk of that sensor for candidate orientations and using genetic algorithm to multisensor multitargets problem, which has NP-complete complexity, then result in the approximated minimum subset of sensors which covers all the targets in networks. Simulation results show the algorithm’s performance and the effect of number of targets on the resulting subset. Yang Yang, Yufei Wang, Dechang Pi, and Ruchuan Wang Copyright © 2014 Yang Yang et al. All rights reserved. RSSI-Based Smooth Localization for Indoor Environment Sun, 29 Jun 2014 10:10:54 +0000 http://www.hindawi.com/journals/tswj/2014/639142/ Radio frequency (RF) technique, for its better penetrability over traditional techniques such as infrared or ultrasound, is widely used for indoor localization and tracking. In this paper, three novel measurements, point decision accuracy, path matching error and wrong jumping ratio, are firstly defined to express the localization efficiency. Then, a novel RSSI-based smooth localization (RSL) algorithm is designed, implemented, and evaluated on the WiFi networks. The tree-based mechanism determines the current position and track of the entity by assigning the weights and accumulative weights for all collected RSSI information of reference points so as to make the localization smooth. The evaluation results indicate that the proposed algorithm brings better localization smoothness of reducing 10% path matching error and 30% wrong jumping ratio over the RADAR system. Yujian Wang, Bin Zhao, and Zhaohui Jiang Copyright © 2014 Yujian Wang et al. All rights reserved. Countermeasures to Avoid Noncooperation in Fully Self-Organized VANETs Thu, 26 Jun 2014 07:43:26 +0000 http://www.hindawi.com/journals/tswj/2014/589563/ The secure and efficient exchange of information in vehicular ad hoc networks (VANETs) involves more challenges than in any other type of ad hoc networks. This paper proposes a new vehicular communication system based on mobile phones for fully distributed and decentralized networks. In these networks, communications depend on individual nodes, which could decrease the efficiency and reliability of transmitted information. Besides, the limitation in the resources of mobile devices is an additional obstacle in the forwarding problem, and the content of the information generated by individual nodes must be considered inherently unreliable. In particular, this paper proposes the application of groups as a basis structure for a cooperation mechanism useful in event generation and in packet retransmission. Its aim is to promote the involvement of nodes in network performance. Given that such participation involves consumption of node resources, a group-based structure is here used not only to reduce communication overload but also to prevent sending false information and to encourage nodes in relaying packets. Several simulations of the proposal have been done, and the results have confirmed that this is a promising approach to increase network efficiency and trust in transmitted information, while reducing the number of selfish nodes in VANETs. Jezabel Molina-Gil, Pino Caballero-Gil, and Cándido Caballero-Gil Copyright © 2014 Jezabel Molina-Gil et al. All rights reserved. A Regev-Type Fully Homomorphic Encryption Scheme Using Modulus Switching Wed, 25 Jun 2014 08:49:08 +0000 http://www.hindawi.com/journals/tswj/2014/983862/ A critical challenge in a fully homomorphic encryption (FHE) scheme is to manage noise. Modulus switching technique is currently the most efficient noise management technique. When using the modulus switching technique to design and implement a FHE scheme, how to choose concrete parameters is an important step, but to our best knowledge, this step has drawn very little attention to the existing FHE researches in the literature. The contributions of this paper are twofold. On one hand, we propose a function of the lower bound of dimension value in the switching techniques depending on the LWE specific security levels. On the other hand, as a case study, we modify the Brakerski FHE scheme (in Crypto 2012) by using the modulus switching technique. We recommend concrete parameter values of our proposed scheme and provide security analysis. Our result shows that the modified FHE scheme is more efficient than the original Brakerski scheme in the same security level. Zhigang Chen, Jian Wang, Liqun Chen, and Xinxia Song Copyright © 2014 Zhigang Chen et al. All rights reserved. An Emergency Packet Forwarding Scheme for V2V Communication Networks Wed, 25 Jun 2014 06:44:21 +0000 http://www.hindawi.com/journals/tswj/2014/480435/ This paper proposes an effective warning message forwarding scheme for cooperative collision avoidance. In an emergency situation, an emergency-detecting vehicle warns the neighbor vehicles via an emergency warning message. Since the transmission range is limited, the warning message is broadcast in a multihop manner. Broadcast packets lead two challenges to forward the warning message in the vehicular network: redundancy of warning messages and competition with nonemergency transmissions. In this paper, we study and address the two major challenges to achieve low latency in delivery of the warning message. To reduce the intervehicle latency and end-to-end latency, which cause chain collisions, we propose a two-way intelligent broadcasting method with an adaptable distance-dependent backoff algorithm. Considering locations of vehicles, the proposed algorithm controls the broadcast of a warning message to reduce redundant EWM messages and adaptively chooses the contention window to compete with nonemergency transmission. Via simulations, we show that our proposed algorithm reduces the probability of rear-end crashes by 70% compared to previous algorithms by reducing the intervehicle delay. We also show that the end-to-end propagation delay of the warning message is reduced by 55%. Faika Hoque and Sungoh Kwon Copyright © 2014 Faika Hoque and Sungoh Kwon. All rights reserved. Towards Accurate Node-Based Detection of P2P Botnets Tue, 24 Jun 2014 14:11:34 +0000 http://www.hindawi.com/journals/tswj/2014/425491/ Botnets are a serious security threat to the current Internet infrastructure. In this paper, we propose a novel direction for P2P botnet detection called node-based detection. This approach focuses on the network characteristics of individual nodes. Based on our model, we examine node’s flows and extract the useful features over a given time period. We have tested our approach on real-life data sets and achieved detection rates of 99-100% and low false positives rates of 0–2%. Comparison with other similar approaches on the same data sets shows that our approach outperforms the existing approaches. Chunyong Yin Copyright © 2014 Chunyong Yin. All rights reserved. Variable Is Better Than Invariable: Sparse VSS-NLMS Algorithms with Application to Adaptive MIMO Channel Estimation Tue, 24 Jun 2014 11:33:14 +0000 http://www.hindawi.com/journals/tswj/2014/274897/ Channel estimation problem is one of the key technical issues in sparse frequency-selective fading multiple-input multiple-output (MIMO) communication systems using orthogonal frequency division multiplexing (OFDM) scheme. To estimate sparse MIMO channels, sparse invariable step-size normalized least mean square (ISS-NLMS) algorithms were applied to adaptive sparse channel estimation (ACSE). It is well known that step-size is a critical parameter which controls three aspects: algorithm stability, estimation performance, and computational cost. However, traditional methods are vulnerable to cause estimation performance loss because ISS cannot balance the three aspects simultaneously. In this paper, we propose two stable sparse variable step-size NLMS (VSS-NLMS) algorithms to improve the accuracy of MIMO channel estimators. First, ASCE is formulated in MIMO-OFDM systems. Second, different sparse penalties are introduced to VSS-NLMS algorithm for ASCE. In addition, difference between sparse ISS-NLMS algorithms and sparse VSS-NLMS ones is explained and their lower bounds are also derived. At last, to verify the effectiveness of the proposed algorithms for ASCE, several selected simulation results are shown to prove that the proposed sparse VSS-NLMS algorithms can achieve better estimation performance than the conventional methods via mean square error (MSE) and bit error rate (BER) metrics. Guan Gui, Zhang-xin Chen, Li Xu, Qun Wan, Jiyan Huang, and Fumiyuki Adachi Copyright © 2014 Guan Gui et al. All rights reserved. A Hop Count Based Heuristic Routing Protocol for Mobile Delay Tolerant Networks Mon, 23 Jun 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/603547/ Routing in delay tolerant networks (DTNs) is a challenge since it must handle network partitioning, long delays, and dynamic topology. Meanwhile, routing protocols of the traditional mobile ad hoc networks (MANETs) cannot work well due to the failure of its assumption that most network connections are available. In this paper, we propose a hop count based heuristic routing protocol by utilizing the information carried by the peripatetic packets in the network. A heuristic function is defined to help in making the routing decision. We formally define a custom operation for square matrices so as to transform the heuristic value calculation into matrix manipulation. Finally, the performance of our proposed algorithm is evaluated by the simulation results, which show the advantage of such self-adaptive routing protocol in the diverse circumstance of DTNs. Lei You, Jianbo Li, Changjiang Wei, Chenqu Dai, Jixing Xu, and Lejuan Hu Copyright © 2014 Lei You et al. All rights reserved. Receiver Diversity Combining Using Evolutionary Algorithms in Rayleigh Fading Channel Thu, 19 Jun 2014 16:02:51 +0000 http://www.hindawi.com/journals/tswj/2014/128195/ In diversity combining at the receiver, the output signal-to-noise ratio (SNR) is often maximized by using the maximal ratio combining (MRC) provided that the channel is perfectly estimated at the receiver. However, channel estimation is rarely perfect in practice, which results in deteriorating the system performance. In this paper, an imperialistic competitive algorithm (ICA) is proposed and compared with two other evolutionary based algorithms, namely, particle swarm optimization (PSO) and genetic algorithm (GA), for diversity combining of signals travelling across the imperfect channels. The proposed algorithm adjusts the combiner weights of the received signal components in such a way that maximizes the SNR and minimizes the bit error rate (BER). The results indicate that the proposed method eliminates the need of channel estimation and can outperform the conventional diversity combining methods. Mohsen Akbari, Mohsen Riahi Manesh, Ayman A. El-Saleh, and Ahmed Wasif Reza Copyright © 2014 Mohsen Akbari et al. All rights reserved. Automating Risk Analysis of Software Design Models Wed, 18 Jun 2014 07:15:33 +0000 http://www.hindawi.com/journals/tswj/2014/805856/ The growth of the internet and networked systems has exposed software to an increased amount of security threats. One of the responses from software developers to these threats is the introduction of security activities in the software development lifecycle. This paper describes an approach to reduce the need for costly human expertise to perform risk analysis in software, which is common in secure development methodologies, by automating threat modeling. Reducing the dependency on security experts aims at reducing the cost of secure development by allowing non-security-aware developers to apply secure development with little to no additional cost, making secure development more accessible. To automate threat modeling two data structures are introduced, identification trees and mitigation trees, to identify threats in software designs and advise mitigation techniques, while taking into account specification requirements and cost concerns. These are the components of our model for automated threat modeling, AutSEC. We validated AutSEC by implementing it in a tool based on data flow diagrams, from the Microsoft security development methodology, and applying it to VOMS, a grid middleware component, to evaluate our model's performance. Maxime Frydman, Guifré Ruiz, Elisa Heymann, Eduardo César, and Barton P. Miller Copyright © 2014 Maxime Frydman et al. All rights reserved. A Novel Deployment Scheme Based on Three-Dimensional Coverage Model for Wireless Sensor Networks Tue, 17 Jun 2014 09:31:44 +0000 http://www.hindawi.com/journals/tswj/2014/846784/ Coverage pattern and deployment strategy are directly related to the optimum allocation of limited resources for wireless sensor networks, such as energy of nodes, communication bandwidth, and computing power, and quality improvement is largely determined by these for wireless sensor networks. A three-dimensional coverage pattern and deployment scheme are proposed in this paper. Firstly, by analyzing the regular polyhedron models in three-dimensional scene, a coverage pattern based on cuboids is proposed, and then relationship between coverage and sensor nodes’ radius is deduced; also the minimum number of sensor nodes to maintain network area’s full coverage is calculated. At last, sensor nodes are deployed according to the coverage pattern after the monitor area is subdivided into finite 3D grid. Experimental results show that, compared with traditional random method, sensor nodes number is reduced effectively while coverage rate of monitor area is ensured using our coverage pattern and deterministic deployment scheme. Fu Xiao, Yang Yang, Ruchuan Wang, and Lijuan Sun Copyright © 2014 Fu Xiao et al. All rights reserved. Joint Subchannel Pairing and Power Control for Cognitive Radio Networks with Amplify-and-Forward Relaying Sun, 15 Jun 2014 08:15:57 +0000 http://www.hindawi.com/journals/tswj/2014/380106/ Dynamic spectrum sharing has drawn intensive attention in cognitive radio networks. The secondary users are allowed to use the available spectrum to transmit data if the interference to the primary users is maintained at a low level. Cooperative transmission for secondary users can reduce the transmission power and thus improve the performance further. We study the joint subchannel pairing and power allocation problem in relay-based cognitive radio networks. The objective is to maximize the sum rate of the secondary user that is helped by an amplify-and-forward relay. The individual power constraints at the source and the relay, the subchannel pairing constraints, and the interference power constraints are considered. The problem under consideration is formulated as a mixed integer programming problem. By the dual decomposition method, a joint optimal subchannel pairing and power allocation algorithm is proposed. To reduce the computational complexity, two suboptimal algorithms are developed. Simulations have been conducted to verify the performance of the proposed algorithms in terms of sum rate and average running time under different conditions. Yanyan Shen, Shuqiang Wang, and Zhiming Wei Copyright © 2014 Yanyan Shen et al. All rights reserved. A Study on Strategic Provisioning of Cloud Computing Services Sun, 15 Jun 2014 06:21:07 +0000 http://www.hindawi.com/journals/tswj/2014/894362/ Cloud computing is currently emerging as an ever-changing, growing paradigm that models “everything-as-a-service.” Virtualised physical resources, infrastructure, and applications are supplied by service provisioning in the cloud. The evolution in the adoption of cloud computing is driven by clear and distinct promising features for both cloud users and cloud providers. However, the increasing number of cloud providers and the variety of service offerings have made it difficult for the customers to choose the best services. By employing successful service provisioning, the essential services required by customers, such as agility and availability, pricing, security and trust, and user metrics can be guaranteed by service provisioning. Hence, continuous service provisioning that satisfies the user requirements is a mandatory feature for the cloud user and vitally important in cloud computing service offerings. Therefore, we aim to review the state-of-the-art service provisioning objectives, essential services, topologies, user requirements, necessary metrics, and pricing mechanisms. We synthesize and summarize different provision techniques, approaches, and models through a comprehensive literature review. A thematic taxonomy of cloud service provisioning is presented after the systematic review. Finally, future research directions and open research issues are identified. Md Whaiduzzaman, Mohammad Nazmul Haque, Md Rejaul Karim Chowdhury, and Abdullah Gani Copyright © 2014 Md Whaiduzzaman et al. All rights reserved. On the Security of a Novel Probabilistic Signature Based on Bilinear Square Diffie-Hellman Problem and Its Extension Thu, 12 Jun 2014 09:30:22 +0000 http://www.hindawi.com/journals/tswj/2014/345686/ Probabilistic signature scheme has been widely used in modern electronic commerce since it could provide integrity, authenticity, and nonrepudiation. Recently, Wu and Lin proposed a novel probabilistic signature (PS) scheme using the bilinear square Diffie-Hellman (BSDH) problem. They also extended it to a universal designated verifier signature (UDVS) scheme. In this paper, we analyze the security of Wu et al.’s PS scheme and UDVS scheme. Through concrete attacks, we demonstrate both of their schemes are not unforgeable. The security analysis shows that their schemes are not suitable for practical applications. Zhenguo Zhao and Wenbo Shi Copyright © 2014 Zhenguo Zhao and Wenbo Shi. All rights reserved. The Collaborative Search by Tag-Based User Profile in Social Media Wed, 11 Jun 2014 07:06:28 +0000 http://www.hindawi.com/journals/tswj/2014/608326/ Recently, we have witnessed the popularity and proliferation of social media applications (e.g., Delicious, Flickr, and YouTube) in the web 2.0 era. The rapid growth of user-generated data results in the problem of information overload to users. Facing such a tremendous volume of data, it is a big challenge to assist the users to find their desired data. To attack this critical problem, we propose the collaborative search approach in this paper. The core idea is that similar users may have common interests so as to help users to find their demanded data. Similar research has been conducted on the user log analysis in web search. However, the rapid growth and change of user-generated data in social media require us to discover a brand-new approach to address the unsolved issues (e.g., how to profile users, how to measure the similar users, and how to depict user-generated resources) rather than adopting existing method from web search. Therefore, we investigate various metrics to identify the similar users (user community). Moreover, we conduct the experiment on two real-life data sets by comparing the Collaborative method with the latest baselines. The empirical results show the effectiveness of the proposed approach and validate our observations. Haoran Xie, Xiaodong Li, Jiantao Wang, Qing Li, and Yi Cai Copyright © 2014 Haoran Xie et al. All rights reserved. A Social Diffusion Model with an Application on Election Simulation Thu, 05 Jun 2014 11:54:47 +0000 http://www.hindawi.com/journals/tswj/2014/180590/ Issues about opinion diffusion have been studied for decades. It has so far no empirical approach to model the interflow and formation of crowd’s opinion in elections due to two reasons. First, unlike the spread of information or flu, individuals have their intrinsic attitudes to election candidates in advance. Second, opinions are generally simply assumed as single values in most diffusion models. However, in this case, an opinion should represent preference toward multiple candidates. Previously done models thus may not intuitively interpret such scenario. This work is to design a diffusion model which is capable of managing the aforementioned scenario. To demonstrate the usefulness of our model, we simulate the diffusion on the network built based on a publicly available bibliography dataset. We compare the proposed model with other well-known models such as independent cascade. It turns out that our model consistently outperforms other models. We additionally investigate electoral issues with our model simulator. Jing-Kai Lou, Fu-Min Wang, Chin-Hua Tsai, San-Chuan Hung, Perng-Hwa Kung, Shou-De Lin, Kuan-Ta Chen, and Chin-Laung Lei Copyright © 2014 Jing-Kai Lou et al. All rights reserved. Next-Generation Internet and Communication Tue, 03 Jun 2014 12:46:58 +0000 http://www.hindawi.com/journals/tswj/2014/342471/ Weifeng Sun, Guoqiang Zhang, Jingjing Zhou, and Vijay Bhuse Copyright © 2014 Weifeng Sun et al. All rights reserved. A Provably Secure Revocable ID-Based Authenticated Group Key Exchange Protocol with Identifying Malicious Participants Sun, 01 Jun 2014 08:53:39 +0000 http://www.hindawi.com/journals/tswj/2014/367264/ The existence of malicious participants is a major threat for authenticated group key exchange (AGKE) protocols. Typically, there are two detecting ways (passive and active) to resist malicious participants in AGKE protocols. In 2012, the revocable identity- (ID-) based public key system (R-IDPKS) was proposed to solve the revocation problem in the ID-based public key system (IDPKS). Afterwards, based on the R-IDPKS, Wu et al. proposed a revocable ID-based AGKE (RID-AGKE) protocol, which adopted a passive detecting way to resist malicious participants. However, it needs three rounds and cannot identify malicious participants. In this paper, we fuse a noninteractive confirmed computation technique to propose the first two-round RID-AGKE protocol with identifying malicious participants, which is an active detecting way. We demonstrate that our protocol is a provably secure AGKE protocol with forward secrecy and can identify malicious participants. When compared with the recently proposed ID/RID-AGKE protocols, our protocol possesses better performance and more robust security properties. Tsu-Yang Wu, Tung-Tso Tsai, and Yuh-Min Tseng Copyright © 2014 Tsu-Yang Wu et al. All rights reserved. The Application of Baum-Welch Algorithm in Multistep Attack Wed, 28 May 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/374260/ The biggest difficulty of hidden Markov model applied to multistep attack is the determination of observations. Now the research of the determination of observations is still lacking, and it shows a certain degree of subjectivity. In this regard, we integrate the attack intentions and hidden Markov model (HMM) and support a method to forecasting multistep attack based on hidden Markov model. Firstly, we train the existing hidden Markov model(s) by the Baum-Welch algorithm of HMM. Then we recognize the alert belonging to attack scenarios with the Forward algorithm of HMM. Finally, we forecast the next possible attack sequence with the Viterbi algorithm of HMM. The results of simulation experiments show that the hidden Markov models which have been trained are better than the untrained in recognition and prediction. Yanxue Zhang, Dongmei Zhao, and Jinxing Liu Copyright © 2014 Yanxue Zhang et al. All rights reserved. Efficient and Provable Secure Pairing-Free Security-Mediated Identity-Based Identification Schemes Mon, 26 May 2014 11:13:04 +0000 http://www.hindawi.com/journals/tswj/2014/170906/ Security-mediated cryptography was first introduced by Boneh et al. in 2001. The main motivation behind security-mediated cryptography was the capability to allow instant revocation of a user’s secret key by necessitating the cooperation of a security mediator in any given transaction. Subsequently in 2003, Boneh et al. showed how to convert a RSA-based security-mediated encryption scheme from a traditional public key setting to an identity-based one, where certificates would no longer be required. Following these two pioneering papers, other cryptographic primitives that utilize a security-mediated approach began to surface. However, the security-mediated identity-based identification scheme (SM-IBI) was not introduced until Chin et al. in 2013 with a scheme built on bilinear pairings. In this paper, we improve on the efficiency results for SM-IBI schemes by proposing two schemes that are pairing-free and are based on well-studied complexity assumptions: the RSA and discrete logarithm assumptions. Ji-Jian Chin, Syh-Yuan Tan, Swee-Huay Heng, and Raphael C.-W. Phan Copyright © 2014 Ji-Jian Chin et al. All rights reserved. A Compact 5.5 GHz Band-Rejected UWB Antenna Using Complementary Split Ring Resonators Thu, 22 May 2014 12:41:35 +0000 http://www.hindawi.com/journals/tswj/2014/528489/ A band-removal property employing microwave frequencies using complementary split ring resonators (CSRRs) is applied to design a compact UWB antenna wishing for the rejection of some frequency band, which is meanwhile exercised by the existing wireless applications. The reported antenna comprises optimization of a circular radiating patch, in which slotted complementary SRRs are implanted. It is printed on low dielectric FR4 substrate material fed by a partial ground plane and a microstrip line. Validated results exhibit that the reported antenna shows a wide bandwidth covering from 3.45 to more than 12 GHz, with a compact dimension of 22 × 26 mm2, and VSWR < 2, observing band elimination of 5.5 GHz WLAN band. M. M. Islam, M. R. I. Faruque, and M. T. Islam Copyright © 2014 M. M. Islam et al. All rights reserved. A New Seamless Transfer Control Strategy of the Microgrid Thu, 22 May 2014 06:38:53 +0000 http://www.hindawi.com/journals/tswj/2014/391945/ A microgrid may operate under two typical modes; the seamless transfer control of the microgrid is very important. The mode conversion controller is installed in microgrid and the control logic of master power is optimized for microgrid mode conversion. In the proposed scheme, master power is very important. The master-power is under the PQ control when microgrid is under grid-connected. And it is under V/F control when the microgrid is under islanding. The microgrid mode controller is used to solve the planned conversion. Three types of conversion are simulated in this paper. The simulation results show the correctness and validity of the mode control scheme. Finally, the implementation and application of the operation and control device are described. Zhaoyun Zhang, Wei Chen, and Zhe Zhang Copyright © 2014 Zhaoyun Zhang et al. All rights reserved. Blind Identification of Convolutional Encoder Parameters Wed, 21 May 2014 08:58:05 +0000 http://www.hindawi.com/journals/tswj/2014/798612/ This paper gives a solution to the blind parameter identification of a convolutional encoder. The problem can be addressed in the context of the noncooperative communications or adaptive coding and modulations (ACM) for cognitive radio networks. We consider an intelligent communication receiver which can blindly recognize the coding parameters of the received data stream. The only knowledge is that the stream is encoded using binary convolutional codes, while the coding parameters are unknown. Some previous literatures have significant contributions for the recognition of convolutional encoder parameters in hard-decision situations. However, soft-decision systems are applied more and more as the improvement of signal processing techniques. In this paper we propose a method to utilize the soft information to improve the recognition performances in soft-decision communication systems. Besides, we propose a new recognition method based on correlation attack to meet low signal-to-noise ratio situations. Finally we give the simulation results to show the efficiency of the proposed methods. Shaojing Su, Jing Zhou, Zhiping Huang, Chunwu Liu, and Yimeng Zhang Copyright © 2014 Shaojing Su et al. All rights reserved. Neighboring and Connectivity-Aware Routing in VANETs Wed, 21 May 2014 06:41:00 +0000 http://www.hindawi.com/journals/tswj/2014/789247/ A novel position-based routing protocol anchor-based connectivity-aware routing (ACAR) for vehicular ad hoc networks (VANETs) is proposed in this paper to ensure connectivity of routes with more successfully delivered packets. Both buses and cars are considered as vehicular nodes running in both clockwise and anticlockwise directions in a city scenario. Both directions are taken into account for faster communication. ACAR is a hybrid protocol, using both the greedy forwarding approach and the store-carry-and-forward approach to minimize the packet drop rate on the basis of certain assumptions. Our solution to situations that occur when the network is sparse and when any (source or intermediate) node has left its initial position makes this protocol different from those existing in the literature. We consider only vehicle-to-vehicle (V2V) communication in which both the source and destination nodes are moving vehicles. Also, no road-side units are considered. Finally, we compare our protocol with A-STAR (a plausible connectivity-aware routing protocol for city environments), and simulation results in NS-2 show improvement in the number of packets delivered to the destination using fewer hops. Also, we show that ACAR has more successfully-delivered long-distance packets with reasonable packet delay than A-STAR. Huma Ghafoor, Insoo Koo, and Nasir-ud-Din Gohar Copyright © 2014 Huma Ghafoor et al. All rights reserved. Design and Optimization of LTE 1800 MIMO Antenna Tue, 20 May 2014 07:38:12 +0000 http://www.hindawi.com/journals/tswj/2014/725806/ A multiple input and multiple output (MIMO) antenna that comprises a printed microstrip antenna and a printed double-L sleeve monopole antenna for LTE 1800 wireless application is presented. The printed double-L sleeve monopole antenna is fed by a 50 ohm coplanar waveguide (CPW). A novel T-shaped microstrip feedline printed on the other side of the PCB is used to excite the waveguide’s outer shell. Isolation characteristics better than −15 dB can be obtained for the proposed MIMO antenna. The proposed antenna can operate in LTE 1800 (1710 MHz–1880 MHz). This antenna exhibits omnidirectional characteristics. The efficiency of the antenna is greater than 70% and has high gain of 2.18 dBi. Huey Shin Wong, Mohammad Tariqul Islam, and Salehin Kibria Copyright © 2014 Huey Shin Wong et al. All rights reserved. Reputation-Based Secure Sensor Localization in Wireless Sensor Networks Tue, 20 May 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/308341/ Location information of sensor nodes in wireless sensor networks (WSNs) is very important, for it makes information that is collected and reported by the sensor nodes spatially meaningful for applications. Since most current sensor localization schemes rely on location information that is provided by beacon nodes for the regular sensor nodes to locate themselves, the accuracy of localization depends on the accuracy of location information from the beacon nodes. Therefore, the security and reliability of the beacon nodes become critical in the localization of regular sensor nodes. In this paper, we propose a reputation-based security scheme for sensor localization to improve the security and the accuracy of sensor localization in hostile or untrusted environments. In our proposed scheme, the reputation of each beacon node is evaluated based on a reputation evaluation model so that regular sensor nodes can get credible location information from highly reputable beacon nodes to accomplish localization. We also perform a set of simulation experiments to demonstrate the effectiveness of the proposed reputation-based security scheme. And our simulation results show that the proposed security scheme can enhance the security and, hence, improve the accuracy of sensor localization in hostile or untrusted environments. Jingsha He, Jing Xu, Xingye Zhu, Yuqiang Zhang, Ting Zhang, and Wanqing Fu Copyright © 2014 Jingsha He et al. All rights reserved. Supporting Seamless Mobility for P2P Live Streaming Mon, 19 May 2014 13:01:10 +0000 http://www.hindawi.com/journals/tswj/2014/134391/ With advent of various mobile devices with powerful networking and computing capabilities, the users' demand to enjoy live video streaming services such as IPTV with mobile devices has been increasing rapidly. However, it is challenging to get over the degradation of service quality due to data loss caused by the handover. Although many handover schemes were proposed at protocol layers below the application layer, they inherently suffer from data loss while the network is being disconnected during the handover. We therefore propose an efficient application-layer handover scheme to support seamless mobility for P2P live streaming. By simulation experiments, we show that the P2P live streaming system with our proposed handover scheme can improve the playback continuity significantly compared to that without our scheme. Eunsam Kim, Sangjin Kim, and Choonhwa Lee Copyright © 2014 Eunsam Kim et al. All rights reserved. Goodness-of-Fit Based Secure Cooperative Spectrum Sensing for Cognitive Radio Network Sun, 18 May 2014 09:11:16 +0000 http://www.hindawi.com/journals/tswj/2014/752507/ Cognitive radio (CR) is a promising technology for improving usage of frequency band. Cognitive radio users (CUs) are allowed to use the bands without interference in operation of licensed users. Reliable sensing information about status of licensed band is a prerequirement for CR network. Cooperative spectrum sensing (CSS) is able to offer an improved sensing reliability compared to individual sensing. However, the sensing performance of CSS can be destroyed due to the appearance of some malicious users. In this paper, we propose a goodness-of-fit (GOF) based cooperative spectrum sensing scheme to detect the dissimilarity between sensing information of normal CUs and that of malicious users, and reject their harmful effect to CSS. The empirical CDF will be used in GOF test to determine the measured distance between distributions of observation sample set according to each hypothesis of licensed user signal. Further, the DS theory is used to combine results of multi-GOF tests. The simulation results demonstrate that the proposed scheme can protect the sensing process against the attack from malicious users. Hiep Vu-Van and Insoo Koo Copyright © 2014 Hiep Vu-Van and Insoo Koo. All rights reserved. Date Attachable Offline Electronic Cash Scheme Sun, 18 May 2014 06:02:22 +0000 http://www.hindawi.com/journals/tswj/2014/216973/ Electronic cash (e-cash) is definitely one of the most popular research topics in the e-commerce field. It is very important that e-cash be able to hold the anonymity and accuracy in order to preserve the privacy and rights of customers. There are two types of e-cash in general, which are online e-cash and offline e-cash. Both systems have their own pros and cons and they can be used to construct various applications. In this paper, we pioneer to propose a provably secure and efficient offline e-cash scheme with date attachability based on the blind signature technique, where expiration date and deposit date can be embedded in an e-cash simultaneously. With the help of expiration date, the bank can manage the huge database much more easily against unlimited growth, and the deposit date cannot be forged so that users are able to calculate the amount of interests they can receive in the future correctly. Furthermore, we offer security analysis and formal proofs for all essential properties of offline e-cash, which are anonymity control, unforgeability, conditional-traceability, and no-swindling. Chun-I Fan, Wei-Zhe Sun, and Hoi-Tung Hau Copyright © 2014 Chun-I Fan et al. All rights reserved. Mobility-Assisted on-Demand Routing Algorithm for MANETs in the Presence of Location Errors Sun, 18 May 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/790103/ We propose a mobility-assisted on-demand routing algorithm for mobile ad hoc networks in the presence of location errors. Location awareness enables mobile nodes to predict their mobility and enhances routing performance by estimating link duration and selecting reliable routes. However, measured locations intrinsically include errors in measurement. Such errors degrade mobility prediction and have been ignored in previous work. To mitigate the impact of location errors on routing, we propose an on-demand routing algorithm taking into account location errors. To that end, we adopt the Kalman filter to estimate accurate locations and consider route confidence in discovering routes. Via simulations, we compare our algorithm and previous algorithms in various environments. Our proposed mobility prediction is robust to the location errors. Trung Kien Vu and Sungoh Kwon Copyright © 2014 Trung Kien Vu and Sungoh Kwon. All rights reserved. A Secure RFID Authentication Protocol Adopting Error Correction Code Sun, 18 May 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/704623/ RFID technology has become popular in many applications; however, most of the RFID products lack security related functionality due to the hardware limitation of the low-cost RFID tags. In this paper, we propose a lightweight mutual authentication protocol adopting error correction code for RFID. Besides, we also propose an advanced version of our protocol to provide key updating. Based on the secrecy of shared keys, the reader and the tag can establish a mutual authenticity relationship. Further analysis of the protocol showed that it also satisfies integrity, forward secrecy, anonymity, and untraceability. Compared with other lightweight protocols, the proposed protocol provides stronger resistance to tracing attacks, compromising attacks and replay attacks. We also compare our protocol with previous works in terms of performance. Chien-Ming Chen, Shuai-Min Chen, Xinying Zheng, Pei-Yu Chen, and Hung-Min Sun Copyright © 2014 Chien-Ming Chen et al. All rights reserved. High Capacity Reversible Watermarking for Audio by Histogram Shifting and Predicted Error Expansion Wed, 14 May 2014 07:51:42 +0000 http://www.hindawi.com/journals/tswj/2014/656251/ Being reversible, the watermarking information embedded in audio signals can be extracted while the original audio data can achieve lossless recovery. Currently, the few reversible audio watermarking algorithms are confronted with following problems: relatively low SNR (signal-to-noise) of embedded audio; a large amount of auxiliary embedded location information; and the absence of accurate capacity control capability. In this paper, we present a novel reversible audio watermarking scheme based on improved prediction error expansion and histogram shifting. First, we use differential evolution algorithm to optimize prediction coefficients and then apply prediction error expansion to output stego data. Second, in order to reduce location map bits length, we introduced histogram shifting scheme. Meanwhile, the prediction error modification threshold according to a given embedding capacity can be computed by our proposed scheme. Experiments show that this algorithm improves the SNR of embedded audio signals and embedding capacity, drastically reduces location map bits length, and enhances capacity control capability. Fei Wang, Zhaoxin Xie, and Zuo Chen Copyright © 2014 Fei Wang et al. All rights reserved. Dual Key Speech Encryption Algorithm Based Underdetermined BSS Wed, 14 May 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/974735/ When the number of the mixed signals is less than that of the source signals, the underdetermined blind source separation (BSS) is a significant difficult problem. Due to the fact that the great amount data of speech communications and real-time communication has been required, we utilize the intractability of the underdetermined BSS problem to present a dual key speech encryption method. The original speech is mixed with dual key signals which consist of random key signals (one-time pad) generated by secret seed and chaotic signals generated from chaotic system. In the decryption process, approximate calculation is used to recover the original speech signals. The proposed algorithm for speech signals encryption can resist traditional attacks against the encryption system, and owing to approximate calculation, decryption becomes faster and more accurate. It is demonstrated that the proposed method has high level of security and can recover the original signals quickly and efficiently yet maintaining excellent audio quality. Huan Zhao, Shaofang He, Zuo Chen, and Xixiang Zhang Copyright © 2014 Huan Zhao et al. All rights reserved. An Optimization Algorithm for Multipath Parallel Allocation for Service Resource in the Simulation Task Workflow Mon, 12 May 2014 12:17:54 +0000 http://www.hindawi.com/journals/tswj/2014/507517/ Service oriented modeling and simulation are hot issues in the field of modeling and simulation, and there is need to call service resources when simulation task workflow is running. How to optimize the service resource allocation to ensure that the task is complete effectively is an important issue in this area. In military modeling and simulation field, it is important to improve the probability of success and timeliness in simulation task workflow. Therefore, this paper proposes an optimization algorithm for multipath service resource parallel allocation, in which multipath service resource parallel allocation model is built and multiple chains coding scheme quantum optimization algorithm is used for optimization and solution. The multiple chains coding scheme quantum optimization algorithm is to extend parallel search space to improve search efficiency. Through the simulation experiment, this paper investigates the effect for the probability of success in simulation task workflow from different optimization algorithm, service allocation strategy, and path number, and the simulation result shows that the optimization algorithm for multipath service resource parallel allocation is an effective method to improve the probability of success and timeliness in simulation task workflow. Zhiteng Wang, Hongjun Zhang, Rui Zhang, Yong Li, and Xuliang Zhang Copyright © 2014 Zhiteng Wang et al. All rights reserved. Efficient Certificate-Based Signcryption Secure against Public Key Replacement Attacks and Insider Attacks Mon, 12 May 2014 11:28:24 +0000 http://www.hindawi.com/journals/tswj/2014/295419/ Signcryption is a useful cryptographic primitive that achieves confidentiality and authentication in an efficient manner. As an extension of signcryption in certificate-based cryptography, certificate-based signcryption preserves the merits of certificate-based cryptography and signcryption simultaneously. In this paper, we present an improved security model of certificate-based signcryption that covers both public key replacement attack and insider security. We show that an existing certificate-based signcryption scheme is insecure in our model. We also propose a new certificate-based signcryption scheme that achieves security against both public key replacement attacks and insider attacks. We prove in the random oracle model that the proposed scheme is chosen-ciphertext secure and existentially unforgeable. Performance analysis shows that the proposed scheme outperforms all the previous certificate-based signcryption schemes in the literature. Yang Lu and Jiguo Li Copyright © 2014 Yang Lu and Jiguo Li. All rights reserved. Inverted S-Shaped Compact Antenna for X-Band Applications Wed, 07 May 2014 07:50:35 +0000 http://www.hindawi.com/journals/tswj/2014/604375/ A novel probe-fed compact inverted S-shaped multifrequency patch antenna is designed. By employing two rectangular slots that change the conventional rectangular patch into an inverted S-shaped patch, the antenna is able to operate in triple frequency in the X-band. The performance criteria of the proposed design have been experimentally verified by fabricating a printed prototype. The measured results show that the −10 dB impedance bandwidth of the proposed antenna at lower band is 5.02% (8.69–9.14 GHz), at middle band is 9.13% (10.47–11.48 GHz), and at upper band is 3.79% (11.53–11.98 GHz). Two elliptical slots are introduced in the ground plane to increase the peak gain. The antenna is excited by a simple probe feeding mechanism. The overall antenna dimension is at a lower resonance frequency of 9.08 GHz. The antenna configuration and parametric investigation are conducted with the help of the high frequency structural simulator, and a good agreement is achieved between the simulated and measured data. The stable gain, omnidirectional radiation pattern, and consistent radiation efficiency in the achieved operating band make the proposed antenna a suitable candidate for X-band applications. M. Samsuzzaman and M. T. Islam Copyright © 2014 M. Samsuzzaman and M. T. Islam. All rights reserved. Effects of ADC Nonlinearity on the Spurious Dynamic Range Performance of Compressed Sensing Wed, 07 May 2014 06:24:41 +0000 http://www.hindawi.com/journals/tswj/2014/143693/ Analog-to-information converter (AIC) plays an important role in the compressed sensing system; it has the potential to significantly extend the capabilities of conventional analog-to-digital converter. This paper evaluates the impact of AIC nonlinearity on the dynamic performance in practical compressed sensing system, which included the nonlinearity introduced by quantization as well as the circuit non-ideality. It presents intuitive yet quantitative insights into the harmonics of quantization output of AIC, and the effect of other AIC nonlinearity on the spurious dynamic range (SFDR) performance is also analyzed. The analysis and simulation results demonstrated that, compared with conventional ADC-based system, the measurement process decorrelates the input signal and the quantization error and alleviate the effect of other decorrelates of AIC, which results in a dramatic increase in spurious free dynamic range (SFDR). Rongzong Kang, Pengwu Tian, and Hongyi Yu Copyright © 2014 Rongzong Kang et al. All rights reserved. Average Gait Differential Image Based Human Recognition Tue, 06 May 2014 12:35:29 +0000 http://www.hindawi.com/journals/tswj/2014/262398/ The difference between adjacent frames of human walking contains useful information for human gait identification. Based on the previous idea a silhouettes difference based human gait recognition method named as average gait differential image (AGDI) is proposed in this paper. The AGDI is generated by the accumulation of the silhouettes difference between adjacent frames. The advantage of this method lies in that as a feature image it can preserve both the kinetic and static information of walking. Comparing to gait energy image (GEI), AGDI is more fit to representation the variation of silhouettes during walking. Two-dimensional principal component analysis (2DPCA) is used to extract features from the AGDI. Experiments on CASIA dataset show that AGDI has better identification and verification performance than GEI. Comparing to PCA, 2DPCA is a more efficient and less memory storage consumption feature extraction method in gait based recognition. Jinyan Chen and Jiansheng Liu Copyright © 2014 Jinyan Chen and Jiansheng Liu. All rights reserved. Analysis of Resonance Response Performance of C-Band Antenna Using Parasitic Element Tue, 06 May 2014 06:25:03 +0000 http://www.hindawi.com/journals/tswj/2014/131374/ Analysis of the resonance response improvement of a planar C-band (4–8 GHz) antenna is proposed using parasitic element method. This parasitic element based method is validated for change in the active and parasitic antenna elements. A novel dual-band antenna for C-band application covering 5.7 GHz and 7.6 GHz is designed and fabricated. The antenna is composed of circular parasitic element with unequal microstrip lines at both sides and a rectangular partial ground plane. A fractional bandwidth of 13.5% has been achieved from 5.5 GHz to 6.3 GHz (WLAN band) for the lower band. The upper band covers from 7.1 GHz to 8 GHz with a fractional bandwidth of 12%. A gain of 6.4 dBi is achieved at the lower frequency and 4 dBi is achieved at the upper frequency. The VSWR of the antenna is less than 2 at the resonance frequency. M. R. Zaman, M. T. Islam, N. Misran, and J. S. Mandeep Copyright © 2014 M. R. Zaman et al. All rights reserved. Modeling and Analysis of Mobility Management in Mobile Communication Networks Mon, 05 May 2014 12:54:54 +0000 http://www.hindawi.com/journals/tswj/2014/250981/ Many strategies have been proposed to reduce the mobility management cost in mobile communication networks. This paper studies the zone-based registration methods that have been adopted by most mobile communication networks. We focus on two special zone-based registration methods, called two-zone registration (2Z) and two-zone registration with implicit registration by outgoing calls (2Zi). We provide a new mathematical model to analyze the exact performance of 2Z and 2Zi. We also present various numerical results, to compare the performance of 2Zi with those of 2Z and one-zone registration (1Z), and show that 2Zi is superior to 2Z as well as 1Z in most cases. Woon Min Baek, Ji Hyun Yoon, and Chesoong Kim Copyright © 2014 Woon Min Baek et al. All rights reserved. A Secure and Fair Joint E-Lottery Protocol Sun, 04 May 2014 09:15:51 +0000 http://www.hindawi.com/journals/tswj/2014/139435/ The attractive huge prize causes people to adore lotteries. Due to the very small probability of winning prizes, the players can enhance their probability of winning by using the method of joint purchase. In spite of many lottery schemes having been proposed, most e-lottery schemes focus on the players’ privacy or computation overhead rather than support a joint purchase protocol on the Internet. In this paper, we use the multisignature and verifiable random function to construct a secure and fair joint e-lottery scheme. The players can check the lottery integrity, and the winning numbers can be verified publicly. Chin-Ling Chen, Yuan-Hao Liao, and Woei-Jiunn Tsaur Copyright © 2014 Chin-Ling Chen et al. All rights reserved. Four-Wave Mixing Crosstalk Suppression Based on the Pairing Combinations of Differently Linear-Polarized Optical Signals Sun, 04 May 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/243795/ A new approach to suppressing the four-wave mixing (FWM) crosstalk by using the pairing combinations of differently linear-polarized optical signals was investigated. The simulation was conducted using a four-channel system, and the total data rate was 40 Gb/s. A comparative study on the suppression of FWM for existing and suggested techniques was conducted by varying the input power from 2 dBm to 14 dBm. The robustness of the proposed technique was examined with two types of optical fiber, namely, single-mode fiber (SMF) and dispersion-shifted fiber (DSF). The FWM power drastically reduced to less than −68 and −25 dBm at an input power of 14 dBm, when the polarization technique was conducted for SMF and DSF, respectively. With the conventional method, the FWM powers were, respectively, −56 and −20 dBm. The system performance greatly improved with the proposed polarization approach, where the bit error rates (BERs) at the first channel were and at received powers of −4.90 and −13.84 dBm for SMF and DSF, respectively. Haider Abd, Norashidah Md. Din, M. H. Al-Mansoori, F. Abdullah, and H. A. Fadhil Copyright © 2014 Haider Abd et al. All rights reserved. Historical Feature Pattern Extraction Based Network Attack Situation Sensing Algorithm Sun, 27 Apr 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/473504/ The situation sequence contains a series of complicated and multivariate random trends, which are very sudden, uncertain, and difficult to recognize and describe its principle by traditional algorithms. To solve the above questions, estimating parameters of super long situation sequence is essential, but very difficult, so this paper proposes a situation prediction method based on historical feature pattern extraction (HFPE). First, HFPE algorithm seeks similar indications from the history situation sequence recorded and weighs the link intensity between occurred indication and subsequent effect. Then it calculates the probability that a certain effect reappears according to the current indication and makes a prediction after weighting. Meanwhile, HFPE method gives an evolution algorithm to derive the prediction deviation from the views of pattern and accuracy. This algorithm can continuously promote the adaptability of HFPE through gradual fine-tuning. The method preserves the rules in sequence at its best, does not need data preprocessing, and can track and adapt to the variation of situation sequence continuously. Yong Zeng, Dacheng Liu, and Zhou Lei Copyright © 2014 Yong Zeng et al. All rights reserved. Distributed Leader-Following Finite-Time Consensus Control for Linear Multiagent Systems under Switching Topology Thu, 24 Apr 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/248041/ This paper investigates the finite-time consensus problem of leader-following multiagent systems. The dynamical models for all following agents and the leader are assumed the same general form of linear system, and the interconnection topology among the agents is assumed to be switching and undirected. We mostly consider the continuous-time case. By assuming that the states of neighbouring agents are known to each agent, a sufficient condition is established for finite-time consensus via a neighbor-based state feedback protocol. While the states of neighbouring agents cannot be available and only the outputs of neighbouring agents can be accessed, the distributed observer-based consensus protocol is proposed for each following agent. A sufficient condition is provided in terms of linear matrix inequalities to design the observer-based consensus protocol, which makes the multiagent systems achieve finite-time consensus under switching topologies. Then, we discuss the counterparts for discrete-time case. Finally, we provide an illustrative example to show the effectiveness of the design approach. Xiaole Xu, Shengyong Chen, and Lixin Gao Copyright © 2014 Xiaole Xu et al. All rights reserved. Towards an Optimal Energy Consumption for Unattended Mobile Sensor Networks through Autonomous Sensor Redeployment Tue, 22 Apr 2014 14:01:08 +0000 http://www.hindawi.com/journals/tswj/2014/716838/ Energy hole is an inherent problem caused by heavier traffic loads of sensor nodes nearer the sink because of more frequent data transmission, which is strongly dependent on the topology induced by the sensor deployment. In this paper, we propose an autonomous sensor redeployment algorithm to balance energy consumption and mitigate energy hole for unattended mobile sensor networks. First, with the target area divided into several equal width coronas, we present a mathematical problem modeling sensor node layout as well as transmission pattern to maximize network coverage and reduce communication cost. And then, by calculating the optimal node density for each corona to avoid energy hole, a fully distributed movement algorithm is proposed, which can achieve an optimal distribution quickly only by pushing or pulling its one-hop neighbors. The simulation results demonstrate that our algorithm achieves a much smaller average moving distance and a much longer network lifetime than existing algorithms and can eliminate the energy hole problem effectively. Jian Chen, Jie Jia, Yingyou Wen, and Dazhe Zhao Copyright © 2014 Jian Chen et al. All rights reserved. Visual Quality Assessment after Network Transmission Incorporating NS2 and Evalvid Tue, 15 Apr 2014 13:55:23 +0000 http://www.hindawi.com/journals/tswj/2014/267403/ On the basis of Evalvid tool integrated in NS2 (Network Simulator version 2), the paper gets new set of tools, myEvalvid, to establish the simulation and evaluation platform for multimedia transmission. Then the paper investigates the effects of various influence factors when multimedia information is transmitted in the network and the relationships among these factors. Based on the analysis, the paper gets different evaluation models, respectively. In this paper, we study the impact on performance of several basic source and network parameters of video streams, namely, GOP (Group of Pictures) pattern, compression quantitative parameters, packet length, and packet error rate. Simulation results show that different parameters lead to different distortion levels which are calculated according to the reconstruction images at the receiver and the original images. The experimental results show that the video transmission and quality evaluation model we designed can evaluate multimedia transmission performance over complex environment very well. Zhengyou Wang, Wan Wang, Yanhui Xia, Zheng Wan, Jin Wang, Liying Li, and Cong Cai Copyright © 2014 Zhengyou Wang et al. All rights reserved. Adaptive Phase Rolling for Opportunistic Beamforming in OFDMA Systems with a Small Number of Users Mon, 14 Apr 2014 08:58:33 +0000 http://www.hindawi.com/journals/tswj/2014/625421/ The performance of opportunistic beamforming might be degraded if the number of users is small. This paper proposes an adaptive opportunistic beamforming technique for orthogonal frequency division multiple access systems, which can produce good results even with a small number of users. This paper also proposes a modified proportional fairness scheduling algorithm, which can further improve the performance of the proposed opportunistic beamforming technique. Minjoong Rim Copyright © 2014 Minjoong Rim. All rights reserved. Characteristic Analysis on UAV-MIMO Channel Based on Normalized Correlation Matrix Mon, 14 Apr 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/206185/ Based on the three-dimensional GBSBCM (geometrically based double bounce cylinder model) channel model of MIMO for unmanned aerial vehicle (UAV), the simple form of UAV space-time-frequency channel correlation function which includes the LOS, SPE, and DIF components is presented. By the methods of channel matrix decomposition and coefficient normalization, the analytic formula of UAV-MIMO normalized correlation matrix is deduced. This formula can be used directly to analyze the condition number of UAV-MIMO channel matrix, the channel capacity, and other characteristic parameters. The simulation results show that this channel correlation matrix can be applied to describe the changes of UAV-MIMO channel characteristics under different parameter settings comprehensively. This analysis method provides a theoretical basis for improving the transmission performance of UAV-MIMO channel. The development of MIMO technology shows practical application value in the field of UAV communication. Gao Xi jun, Chen Zi li, and Hu Yong Jiang Copyright © 2014 Gao Xi jun et al. All rights reserved. Password-Only Authenticated Three-Party Key Exchange with Provable Security in the Standard Model Mon, 14 Apr 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/825072/ Protocols for password-only authenticated key exchange (PAKE) in the three-party setting allow two clients registered with the same authentication server to derive a common secret key from their individual password shared with the server. Existing three-party PAKE protocols were proven secure under the assumption of the existence of random oracles or in a model that does not consider insider attacks. Therefore, these protocols may turn out to be insecure when the random oracle is instantiated with a particular hash function or an insider attack is mounted against the partner client. The contribution of this paper is to present the first three-party PAKE protocol whose security is proven without any idealized assumptions in a model that captures insider attacks. The proof model we use is a variant of the indistinguishability-based model of Bellare, Pointcheval, and Rogaway (2000), which is one of the most widely accepted models for security analysis of password-based key exchange protocols. We demonstrated that our protocol achieves not only the typical indistinguishability-based security of session keys but also the password security against undetectable online dictionary attacks. Junghyun Nam, Kim-Kwang Raymond Choo, Junghwan Kim, Hyun-Kyu Kang, Jinsoo Kim, Juryon Paik, and Dongho Won Copyright © 2014 Junghyun Nam et al. All rights reserved. Compressive Sensing Based Bayesian Sparse Channel Estimation for OFDM Communication Systems: High Performance and Low Complexity Thu, 10 Apr 2014 14:07:45 +0000 http://www.hindawi.com/journals/tswj/2014/927894/ In orthogonal frequency division modulation (OFDM) communication systems, channel state information (CSI) is required at receiver due to the fact that frequency-selective fading channel leads to disgusting intersymbol interference (ISI) over data transmission. Broadband channel model is often described by very few dominant channel taps and they can be probed by compressive sensing based sparse channel estimation (SCE) methods, for example, orthogonal matching pursuit algorithm, which can take the advantage of sparse structure effectively in the channel as for prior information. However, these developed methods are vulnerable to both noise interference and column coherence of training signal matrix. In other words, the primary objective of these conventional methods is to catch the dominant channel taps without a report of posterior channel uncertainty. To improve the estimation performance, we proposed a compressive sensing based Bayesian sparse channel estimation (BSCE) method which cannot only exploit the channel sparsity but also mitigate the unexpected channel uncertainty without scarifying any computational complexity. The proposed method can reveal potential ambiguity among multiple channel estimators that are ambiguous due to observation noise or correlation interference among columns in the training matrix. Computer simulations show that proposed method can improve the estimation performance when comparing with conventional SCE methods. Guan Gui, Li Xu, Lin Shan, and Fumiyuki Adachi Copyright © 2014 Guan Gui et al. All rights reserved. Code-Time Diversity for Direct Sequence Spread Spectrum Systems Thu, 10 Apr 2014 12:04:48 +0000 http://www.hindawi.com/journals/tswj/2014/146186/ Time diversity is achieved in direct sequence spread spectrum by receiving different faded delayed copies of the transmitted symbols from different uncorrelated channel paths when the transmission signal bandwidth is greater than the coherence bandwidth of the channel. In this paper, a new time diversity scheme is proposed for spread spectrum systems. It is called code-time diversity. In this new scheme, spreading codes are used to transmit one data symbol over successive symbols interval. The diversity order in the proposed scheme equals to the number of the used spreading codes multiplied by the number of the uncorrelated paths of the channel . The paper represents the transmitted signal model. Two demodulators structures will be proposed based on the received signal models from Rayleigh flat and frequency selective fading channels. Probability of error in the proposed diversity scheme is also calculated for the same two fading channels. Finally, simulation results are represented and compared with that of maximal ration combiner (MRC) and multiple-input and multiple-output (MIMO) systems. A. Y. Hassan Copyright © 2014 A. Y. Hassan. All rights reserved. A Complete Hierarchical Key Management Scheme for Heterogeneous Wireless Sensor Networks Thu, 10 Apr 2014 11:12:46 +0000 http://www.hindawi.com/journals/tswj/2014/816549/ Heterogeneous cluster-based wireless sensor networks (WSN) attracted increasing attention recently. Obviously, the clustering makes the entire networks hierarchical; thus, several kinds of keys are required for hierarchical network topology. However, most existing key management schemes for it place more emphasis on pairwise key management schemes or key predistribution schemes and neglect the property of hierarchy. In this paper, we propose a complete hierarchical key management scheme which only utilizes symmetric cryptographic algorithms and low cost operations for heterogeneous cluster-based WSN. Our scheme considers four kinds of keys, which are an individual key, a cluster key, a master key, and pairwise keys, for each sensor node. Finally, the analysis and experiments demonstrate that the proposed scheme is secure and efficient; thus, it is suitable for heterogeneous cluster-based WSN. Chien-Ming Chen, Xinying Zheng, and Tsu-Yang Wu Copyright © 2014 Chien-Ming Chen et al. All rights reserved. Reducing Side Effects of Hiding Sensitive Itemsets in Privacy Preserving Data Mining Thu, 10 Apr 2014 08:51:11 +0000 http://www.hindawi.com/journals/tswj/2014/235837/ Data mining is traditionally adopted to retrieve and analyze knowledge from large amounts of data. Private or confidential data may be sanitized or suppressed before it is shared or published in public. Privacy preserving data mining (PPDM) has thus become an important issue in recent years. The most general way of PPDM is to sanitize the database to hide the sensitive information. In this paper, a novel hiding-missing-artificial utility (HMAU) algorithm is proposed to hide sensitive itemsets through transaction deletion. The transaction with the maximal ratio of sensitive to nonsensitive one is thus selected to be entirely deleted. Three side effects of hiding failures, missing itemsets, and artificial itemsets are considered to evaluate whether the transactions are required to be deleted for hiding sensitive itemsets. Three weights are also assigned as the importance to three factors, which can be set according to the requirement of users. Experiments are then conducted to show the performance of the proposed algorithm in execution time, number of deleted transactions, and number of side effects. Chun-Wei Lin, Tzung-Pei Hong, and Hung-Chuan Hsu Copyright © 2014 Chun-Wei Lin et al. All rights reserved. In-Band Asymmetry Compensation for Accurate Time/Phase Transport over Optical Transport Network Thu, 10 Apr 2014 08:18:44 +0000 http://www.hindawi.com/journals/tswj/2014/408613/ The demands of precise time/phase synchronization have been increasing recently due to the next generation of telecommunication synchronization. This paper studies the issues that are relevant to distributing accurate time/phase over optical transport network (OTN). Each node and link can introduce asymmetry, which affects the adequate time/phase accuracy over the networks. In order to achieve better accuracy, protocol level full timing support is used (e.g., Telecom-Boundary clock). Due to chromatic dispersion, the use of different wavelengths consequently causes fiber link delay asymmetry. The analytical result indicates that it introduces significant time error (i.e., phase offset) within 0.3397 ns/km in C-band or 0.3943 ns/km in L-band depending on the wavelength spacing. With the proposed scheme in this paper, the fiber link delay asymmetry can be compensated relying on the estimated mean fiber link delay by the Telecom-Boundary clock, while the OTN control plane is responsible for processing the fiber link delay asymmetry to determine the asymmetry compensation in the timing chain. Sammy Siu, Wen-Hung Tseng, Hsiu-fang Hu, Shinn-Yan Lin, Chia-Shu Liao, and Yi-Liang Lai Copyright © 2014 Sammy Siu et al. All rights reserved. Content Patterns in Topic-Based Overlapping Communities Wed, 09 Apr 2014 09:19:51 +0000 http://www.hindawi.com/journals/tswj/2014/105428/ Understanding the underlying community structure is an important challenge in social network analysis. Most state-of-the-art algorithms only consider structural properties to detect disjoint subcommunities and do not include the fact that people can belong to more than one community and also ignore the information contained in posts that users have made. To tackle this problem, we developed a novel methodology to detect overlapping subcommunities in online social networks and a method to analyze the content patterns for each subcommunities using topic models. This paper presents our main contribution, a hybrid algorithm which combines two different overlapping sub-community detection approaches: the first one considers the graph structure of the network (topology-based subcommunities detection approach) and the second one takes the textual information of the network nodes into consideration (topic-based subcommunities detection approach). Additionally we provide a method to analyze and compare the content generated. Tests on real-world virtual communities show that our algorithm outperforms other methods. Sebastián A. Ríos and Ricardo Muñoz Copyright © 2014 Sebastián A. Ríos and Ricardo Muñoz. All rights reserved. Multichannel Broadcast Based on Home Channel for Cognitive Radio Sensor Networks Wed, 09 Apr 2014 09:07:09 +0000 http://www.hindawi.com/journals/tswj/2014/725210/ Considering the limited resources and the dynamic spectrum distribution in the cognitive radio sensor networks (CRSN), a half-duplex Multichannel broadcast protocol for CRSN is presented based on the home channel. This protocol maintains the networks topology only through the home channel, so there is no need for the public channel to transmit the control information and no need for the synchronization. After network initialization, node broadcasts data via home channel in half-duplex transmission way. The simulation results show that, compared with complete broadcast, the proposed protocol effectively reduces broadcast delay and overhead. Fanzi Zeng, Yuting Tang, and Jianjie Pu Copyright © 2014 Fanzi Zeng et al. All rights reserved. Separable and Error-Free Reversible Data Hiding in Encrypted Image with High Payload Sun, 06 Apr 2014 06:23:56 +0000 http://www.hindawi.com/journals/tswj/2014/604876/ This paper proposes a separable reversible data-hiding scheme in encrypted image which offers high payload and error-free data extraction. The cover image is partitioned into nonoverlapping blocks and multigranularity encryption is applied to obtain the encrypted image. The data hider preprocesses the encrypted image and randomly selects two basic pixels in each block to estimate the block smoothness and indicate peak points. Additional data are embedded into blocks in the sorted order of block smoothness by using local histogram shifting under the guidance of the peak points. At the receiver side, image decryption and data extraction are separable and can be free to choose. Compared to previous approaches, the proposed method is simpler in calculation while offering better performance: larger payload, better embedding quality, and error-free data extraction, as well as image recovery. Zhaoxia Yin, Bin Luo, and Wien Hong Copyright © 2014 Zhaoxia Yin et al. All rights reserved. Modeling and Simulation of Complex Network Attributes on Coordinating Large Multiagent System Thu, 03 Apr 2014 08:25:13 +0000 http://www.hindawi.com/journals/tswj/2014/412479/ With the expansion of distributed multiagent systems, traditional coordination strategy becomes a severe bottleneck when the system scales up to hundreds of agents. The key challenge is that in typical large multiagent systems, sparsely distributed agents can only communicate directly with very few others and the network is typically modeled as an adaptive complex network. In this paper, we present simulation testbed CoordSim built to model the coordination of network centric multiagent systems. Based on the token-based strategy, the coordination can be built as a communication decision problem that agents make decisions to target communications and pass them over to the capable agents who will potentially benefit the team most. We have theoretically analyzed that the characters of complex network make a significant difference with both random and intelligent coordination strategies, which may contribute to future multiagent algorithm design. Yang Xu, Xiang Li, and Ming Liu Copyright © 2014 Yang Xu et al. All rights reserved. Discovering the Influences of Complex Network Effects on Recovering Large Scale Multiagent Systems Wed, 02 Apr 2014 13:41:00 +0000 http://www.hindawi.com/journals/tswj/2014/407639/ Building efficient distributed coordination algorithms is critical for the large scale multiagent system design, and the communication network has been shown as a key factor to influence system performance even under the same coordination protocol. Although many distributed algorithm designs have been proved to be feasible to build their functions in the large scale multiagent systems as claimed, the performances may not be stable if the multiagent networks were organized with different complex network topologies. For example, if the network was recovered from the broken links or disfunction nodes, the network topology might have been shifted. Therefore, their influences on the overall multiagent system performance are unknown. In this paper, we have made an initial effort to find how a standard network recovery policy, MPLS algorithm, may change the network topology of the multiagent system in terms of network congestion. We have established that when the multiagent system is organized as different network topologies according to different complex network attributes, the network shifts in different ways. Those interesting discoveries are helpful to predict how complex network attributes influence on system performance and in turn are useful for new algorithm designs that make a good use of those attributes. Yang Xu, Pengfei Liu, Xiang Li, and Wei Ren Copyright © 2014 Yang Xu et al. All rights reserved. A Novel Joint Problem of Routing, Scheduling, and Variable-Width Channel Allocation in WMNs Wed, 02 Apr 2014 11:59:24 +0000 http://www.hindawi.com/journals/tswj/2014/754749/ This paper investigates a novel joint problem of routing, scheduling, and channel allocation for single-radio multichannel wireless mesh networks in which multiple channel widths can be adjusted dynamically through a new software technology so that more concurrent transmissions and suppressed overlapping channel interference can be achieved. Although the previous works have studied this joint problem, their linear programming models for the problem were not incorporated with some delicate constraints. As a result, this paper first constructs a linear programming model with more practical concerns and then proposes a simulated annealing approach with a novel encoding mechanism, in which the configurations of multiple time slots are devised to characterize the dynamic transmission process. Experimental results show that our approach can find the same or similar solutions as the optimal solutions for smaller-scale problems and can efficiently find good-quality solutions for a variety of larger-scale problems. Chun-Cheng Lin, Wan-Yu Liu, Chun-Hung Chou, and Der-Jiunn Deng Copyright © 2014 Chun-Cheng Lin et al. All rights reserved. A Coverage and Slicing Dependencies Analysis for Seeking Software Security Defects Wed, 02 Apr 2014 11:57:31 +0000 http://www.hindawi.com/journals/tswj/2014/463912/ Software security defects have a serious impact on the software quality and reliability. It is a major hidden danger for the operation of a system that a software system has some security flaws. When the scale of the software increases, its vulnerability has becoming much more difficult to find out. Once these vulnerabilities are exploited, it may lead to great loss. In this situation, the concept of Software Assurance is carried out by some experts. And the automated fault localization technique is a part of the research of Software Assurance. Currently, automated fault localization method includes coverage based fault localization (CBFL) and program slicing. Both of the methods have their own location advantages and defects. In this paper, we have put forward a new method, named Reverse Data Dependence Analysis Model, which integrates the two methods by analyzing the program structure. On this basis, we finally proposed a new automated fault localization method. This method not only is automation lossless but also changes the basic location unit into single sentence, which makes the location effect more accurate. Through several experiments, we proved that our method is more effective. Furthermore, we analyzed the effectiveness among these existing methods and different faults. Hui He, Dongyan Zhang, Min Liu, Weizhe Zhang, and Dongmin Gao Copyright © 2014 Hui He et al. All rights reserved. An Improved Clustering Algorithm of Tunnel Monitoring Data for Cloud Computing Wed, 02 Apr 2014 08:09:16 +0000 http://www.hindawi.com/journals/tswj/2014/630986/ With the rapid development of urban construction, the number of urban tunnels is increasing and the data they produce become more and more complex. It results in the fact that the traditional clustering algorithm cannot handle the mass data of the tunnel. To solve this problem, an improved parallel clustering algorithm based on k-means has been proposed. It is a clustering algorithm using the MapReduce within cloud computing that deals with data. It not only has the advantage of being used to deal with mass data but also is more efficient. Moreover, it is able to compute the average dissimilarity degree of each cluster in order to clean the abnormal data. Luo Zhong, KunHao Tang, Lin Li, Guang Yang, and JingJing Ye Copyright © 2014 Luo Zhong et al. All rights reserved. Identifying Network Public Opinion Leaders Based on Markov Logic Networks Tue, 01 Apr 2014 06:03:40 +0000 http://www.hindawi.com/journals/tswj/2014/268592/ Public opinion emergencies have important effect on social activities. Recognition of special communities like opinion leaders can contribute to a comprehensive understanding of the development trend of public opinion. In this paper, a network opinion leader recognition method based on relational data was put forward, and an opinion leader recognition system integrating public opinion data acquisition module, data characteristic selection, and fusion module as well as opinion leader discovery module based on Markov Logic Networks was designed. The designed opinion leader recognition system not only can overcome the incomplete data acquisition and isolated task of traditional methods, but also can recognize opinion leaders comprehensively with considerations to multiple problems by using the relational model. Experimental results demonstrated that, compared with the traditional methods, the proposed method can provide a more accurate opinion leader recognition and has good noise immunity. Weizhe Zhang, Xiaoqiang Li, Hui He, and Xing Wang Copyright © 2014 Weizhe Zhang et al. All rights reserved. SVM-Based Spectrum Mobility Prediction Scheme in Mobile Cognitive Radio Networks Sun, 30 Mar 2014 13:29:08 +0000 http://www.hindawi.com/journals/tswj/2014/395212/ Spectrum mobility as an essential issue has not been fully investigated in mobile cognitive radio networks (CRNs). In this paper, a novel support vector machine based spectrum mobility prediction (SVM-SMP) scheme is presented considering time-varying and space-varying characteristics simultaneously in mobile CRNs. The mobility of cognitive users (CUs) and the working activities of primary users (PUs) are analyzed in theory. And a joint feature vector extraction (JFVE) method is proposed based on the theoretical analysis. Then spectrum mobility prediction is executed through the classification of SVM with a fast convergence speed. Numerical results validate that SVM-SMP gains better short-time prediction accuracy rate and miss prediction rate performance than the two algorithms just depending on the location and speed information. Additionally, a rational parameter design can remedy the prediction performance degradation caused by high speed SUs with strong randomness movements. Yao Wang, Zhongzhao Zhang, Lin Ma, and Jiamei Chen Copyright © 2014 Yao Wang et al. All rights reserved. Trusted Measurement Model Based on Multitenant Behaviors Sun, 30 Mar 2014 10:05:09 +0000 http://www.hindawi.com/journals/tswj/2014/384967/ With a fast growing pervasive computing, especially cloud computing, the behaviour measurement is at the core and plays a vital role. A new behaviour measurement tailored for Multitenants in cloud computing is needed urgently to fundamentally establish trust relationship. Based on our previous research, we propose an improved trust relationship scheme which captures the world of cloud computing where multitenants share the same physical computing platform. Here, we first present the related work on multitenant behaviour; secondly, we give the scheme of behaviour measurement where decoupling of multitenants is taken into account; thirdly, we explicitly explain our decoupling algorithm for multitenants; fourthly, we introduce a new way of similarity calculation for deviation control, which fits the coupled multitenants under study well; lastly, we design the experiments to test our scheme. Zhen-Hu Ning, Chang-Xiang Shen, Yong Zhao, and Peng Liang Copyright © 2014 Zhen-Hu Ning et al. All rights reserved. Secure and Fair Cluster Head Selection Protocol for Enhancing Security in Mobile Ad Hoc Networks Thu, 27 Mar 2014 09:49:36 +0000 http://www.hindawi.com/journals/tswj/2014/608984/ Mobile ad hoc networks (MANETs) are wireless networks consisting of number of autonomous mobile devices temporarily interconnected into a network by wireless media. MANETs become one of the most prevalent areas of research in the recent years. Resource limitations, energy efficiency, scalability, and security are the great challenging issues in MANETs. Due to its deployment nature, MANETs are more vulnerable to malicious attack. The secure routing protocols perform very basic security related functions which are not sufficient to protect the network. In this paper, a secure and fair cluster head selection protocol (SFCP) is proposed which integrates security factors into the clustering approach for achieving attacker identification and classification. Byzantine agreement based cooperative technique is used for attacker identification and classification to make the network more attack resistant. SFCP used to solve this issue by making the nodes that are totally surrounded by malicious neighbors adjust dynamically their belief and disbelief thresholds. The proposed protocol selects the secure and energy efficient cluster head which acts as a local detector without imposing overhead to the clustering performance. SFCP is simulated in network simulator 2 and compared with two protocols including AODV and CBRP. B. Paramasivan and M. Kaliappan Copyright © 2014 B. Paramasivan and M. Kaliappan. All rights reserved. Robust Filtering for a Class of Complex Networks with Stochastic Packet Dropouts and Time Delays Thu, 27 Mar 2014 08:27:36 +0000 http://www.hindawi.com/journals/tswj/2014/560234/ The robust filtering problem is investigated for a class of complex network systems which has stochastic packet dropouts and time delays, combined with disturbance inputs. The packet dropout phenomenon occurs in a random way and the occurrence probability for each measurement output node is governed by an individual random variable. Besides, the time delay phenomenon is assumed to occur in a nonlinear vector-valued function. We aim to design a filter such that the estimation error converges to zero exponentially in the mean square, while the disturbance rejection attenuation is constrained to a given level by means of the performance index. By constructing the proper Lyapunov-Krasovskii functional, we acquire sufficient conditions to guarantee the stability of the state detection observer for the discrete systems, and the observer gain is also derived by solving linear matrix inequalities. Finally, an illustrative example is provided to show the usefulness and effectiveness of the proposed design method. Jie Zhang, Ming Lyu, Hamid Reza Karimi, Pengfei Guo, and Yuming Bo Copyright © 2014 Jie Zhang et al. All rights reserved. On the Improvement of Wiener Attack on RSA with Small Private Exponent Thu, 27 Mar 2014 07:43:29 +0000 http://www.hindawi.com/journals/tswj/2014/650537/ RSA system is based on the hardness of the integer factorization problem (IFP). Given an RSA modulus , it is difficult to determine the prime factors and efficiently. One of the most famous short exponent attacks on RSA is the Wiener attack. In 1997, Verheul and van Tilborg use an exhaustive search to extend the boundary of the Wiener attack. Their result shows that the cost of exhaustive search is bits when extending the Weiner's boundary r bits. In this paper, we first reduce the cost of exhaustive search from bits to bits. Then, we propose a method named EPF. With EPF, the cost of exhaustive search is further reduced to bits when we extend Weiner's boundary bits. It means that our result is 214 times faster than Verheul and van Tilborg's result. Besides, the security boundary is extended 7 bits. Mu-En Wu, Chien-Ming Chen, Yue-Hsun Lin, and Hung-Min Sun Copyright © 2014 Mu-En Wu et al. All rights reserved. Transition Characteristic Analysis of Traffic Evolution Process for Urban Traffic Network Thu, 27 Mar 2014 07:20:26 +0000 http://www.hindawi.com/journals/tswj/2014/603274/ The characterization of the dynamics of traffic states remains fundamental to seeking for the solutions of diverse traffic problems. To gain more insights into traffic dynamics in the temporal domain, this paper explored temporal characteristics and distinct regularity in the traffic evolution process of urban traffic network. We defined traffic state pattern through clustering multidimensional traffic time series using self-organizing maps and construct a pattern transition network model that is appropriate for representing and analyzing the evolution progress. The methodology is illustrated by an application to data flow rate of multiple road sections from Network of Shenzhen’s Nanshan District, China. Analysis and numerical results demonstrated that the methodology permits extracting many useful traffic transition characteristics including stability, preference, activity, and attractiveness. In addition, more information about the relationships between these characteristics was extracted, which should be helpful in understanding the complex behavior of the temporal evolution features of traffic patterns. Longfei Wang, Hong Chen, and Yang Li Copyright © 2014 Longfei Wang et al. All rights reserved. Novel Image Encryption Scheme Based on Chebyshev Polynomial and Duffing Map Wed, 26 Mar 2014 08:54:39 +0000 http://www.hindawi.com/journals/tswj/2014/283639/ We present a novel image encryption algorithm using Chebyshev polynomial based on permutation and substitution and Duffing map based on substitution. Comprehensive security analysis has been performed on the designed scheme using key space analysis, visual testing, histogram analysis, information entropy calculation, correlation coefficient analysis, differential analysis, key sensitivity test, and speed test. The study demonstrates that the proposed image encryption algorithm shows advantages of more than key space and desirable level of security based on the good statistical results and theoretical arguments. Borislav Stoyanov and Krasimir Kordov Copyright © 2014 Borislav Stoyanov and Krasimir Kordov. All rights reserved. Privacy-Preserving Location-Based Query Using Location Indexes and Parallel Searching in Distributed Networks Tue, 25 Mar 2014 08:59:12 +0000 http://www.hindawi.com/journals/tswj/2014/751845/ An efficient location-based query algorithm of protecting the privacy of the user in the distributed networks is given. This algorithm utilizes the location indexes of the users and multiple parallel threads to search and select quickly all the candidate anonymous sets with more users and their location information with more uniform distribution to accelerate the execution of the temporal-spatial anonymous operations, and it allows the users to configure their custom-made privacy-preserving location query requests. The simulated experiment results show that the proposed algorithm can offer simultaneously the location query services for more users and improve the performance of the anonymous server and satisfy the anonymous location requests of the users. Cheng Zhong, Lei Liu, and Jing Zhao Copyright © 2014 Cheng Zhong et al. All rights reserved. Assessment on Knowledge Network Sharing Capability of Industrial Cluster Based on Dempster-Shafer Theory of Evidence Mon, 24 Mar 2014 06:42:21 +0000 http://www.hindawi.com/journals/tswj/2014/810782/ Based on Theory of Evidence and reviewing research papers concerned, a concept model of knowledge sharing network among industrial cluster firms, which can be applied to assess knowledge sharing capacity, has been built. Next, the authors create a set of assessment index systems including twelve subindexes under four principle indexes. In this study, ten experts in the same field were invited to score all the indexes of knowledge sharing capacity concerning one certain industrial cluster. The research result shows relatively high knowledge network sharing capacity among the certain industrial cluster firms. Another conclusion is that the assessment method with Theory of Evidence is feasible to conduct such a research. Shengli Dai and Hailin Zhang Copyright © 2014 Shengli Dai and Hailin Zhang. All rights reserved. Modeling of Information Diffusion in Twitter-Like Social Networks under Information Overload Sun, 23 Mar 2014 13:20:50 +0000 http://www.hindawi.com/journals/tswj/2014/914907/ Due to the existence of information overload in social networks, it becomes increasingly difficult for users to find useful information according to their interests. This paper takes Twitter-like social networks into account and proposes models to characterize the process of information diffusion under information overload. Users are classified into different types according to their in-degrees and out-degrees, and user behaviors are generalized into two categories: generating and forwarding. View scope is introduced to model the user information-processing capability under information overload, and the average number of times a message appears in view scopes after it is generated by a given type user is adopted to characterize the information diffusion efficiency, which is calculated theoretically. To verify the accuracy of theoretical analysis results, we conduct simulations and provide the simulation results, which are consistent with the theoretical analysis results perfectly. These results are of importance to understand the diffusion dynamics in social networks, and this analysis framework can be extended to consider more realistic situations. Pei Li, Wei Li, Hui Wang, and Xin Zhang Copyright © 2014 Pei Li et al. All rights reserved. Dynamic Resource Allocation in Hybrid Access Femtocell Network Thu, 20 Mar 2014 07:07:11 +0000 http://www.hindawi.com/journals/tswj/2014/539720/ Intercell interference is one of the most challenging issues in femtocell deployment under the coverage of existing macrocell. Allocation of resources between femtocell and macrocell is essential to counter the effects of interference in dense femtocell networks. Advances in resource management strategies have improved the control mechanism for interference reduction at lower node density, but most of them are ineffective at higher node density. In this paper, a dynamic resource allocation management algorithm (DRAMA) for spectrum shared hybrid access OFDMA femtocell network is proposed. To reduce the macro-femto-tier interference and to improve the quality of service, the proposed algorithm features a dynamic resource allocation scheme by controlling them both centrally and locally. The proposed scheme focuses on Femtocell Access Point (FAP) owners’ satisfaction and allows maximum utilization of available resources based on congestion in the network. A simulation environment is developed to study the quantitative performance of DRAMA in hybrid access-control femtocell network and compare it to closed and open access mechanisms. The performance analysis shows that higher number of random users gets connected to the FAP without compromising FAP owners’ satisfaction allowing the macrocell to offload a large number of users in a dense heterogeneous network. Afaz Uddin Ahmed, Mohammad Tariqul Islam, Mahamod Ismail, and Mohammad Ghanbarisabagh Copyright © 2014 Afaz Uddin Ahmed et al. All rights reserved. An Improved Proportionate Normalized Least-Mean-Square Algorithm for Broadband Multipath Channel Estimation Thu, 20 Mar 2014 06:35:46 +0000 http://www.hindawi.com/journals/tswj/2014/572969/ To make use of the sparsity property of broadband multipath wireless communication channels, we mathematically propose an -norm-constrained proportionate normalized least-mean-square (LP-PNLMS) sparse channel estimation algorithm. A general -norm is weighted by the gain matrix and is incorporated into the cost function of the proportionate normalized least-mean-square (PNLMS) algorithm. This integration is equivalent to adding a zero attractor to the iterations, by which the convergence speed and steady-state performance of the inactive taps are significantly improved. Our simulation results demonstrate that the proposed algorithm can effectively improve the estimation performance of the PNLMS-based algorithm for sparse channel estimation applications. Yingsong Li and Masanori Hamamura Copyright © 2014 Yingsong Li and Masanori Hamamura. All rights reserved. Analyses of Crime Patterns in NIBRS Data Based on a Novel Graph Theory Clustering Method: Virginia as a Case Study Thu, 20 Mar 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/492461/ This paper suggests a novel clustering method for analyzing the National Incident-Based Reporting System (NIBRS) data, which include the determination of correlation of different crime types, the development of a likelihood index for crimes to occur in a jurisdiction, and the clustering of jurisdictions based on crime type. The method was tested by using the 2005 assault data from 121 jurisdictions in Virginia as a test case. The analyses of these data show that some different crime types are correlated and some different crime parameters are correlated with different crime types. The analyses also show that certain jurisdictions within Virginia share certain crime patterns. This information assists with constructing a pattern for a specific crime type and can be used to determine whether a jurisdiction may be more likely to see this type of crime occur in their area. Peixin Zhao, Marjorie Darrah, Jim Nolan, and Cun-Quan Zhang Copyright © 2014 Peixin Zhao et al. All rights reserved. Optical Frequency Upconversion Technique for Transmission of Wireless MIMO-Type Signals over Optical Fiber Sun, 16 Mar 2014 17:09:31 +0000 http://www.hindawi.com/journals/tswj/2014/170471/ The optical fiber is well adapted to pass multiple wireless signals having different carrier frequencies by using radio-over-fiber (ROF) technique. However, multiple wireless signals which have the same carrier frequency cannot propagate over a single optical fiber, such as wireless multi-input multi-output (MIMO) signals feeding multiple antennas in the fiber wireless (FiWi) system. A novel optical frequency upconversion (OFU) technique is proposed to solve this problem. In this paper, the novel OFU approach is used to transmit three wireless MIMO signals over a 20 km standard single mode fiber (SMF). The OFU technique exploits one optical source to produce multiple wavelengths by delivering it to a LiNbO3 external optical modulator. The wireless MIMO signals are then modulated by LiNbO3 optical intensity modulators separately using the generated optical carriers from the OFU process. These modulators use the optical single-sideband with carrier (OSSB+C) modulation scheme to optimize the system performance against the fiber dispersion effect. Each wireless MIMO signal is with a 2.4 GHz or 5 GHz carrier frequency, 1 Gb/s data rate, and 16-quadrature amplitude modulation (QAM). The crosstalk between the wireless MIMO signals is highly suppressed, since each wireless MIMO signal is carried on a specific optical wavelength. R. Q. Shaddad, A. B. Mohammad, S. A. Al-Gailani, and A. M. Al-Hetar Copyright © 2014 R. Q. Shaddad et al. All rights reserved. Multidimensional Optimization of Signal Space Distance Parameters in WLAN Positioning Sun, 16 Mar 2014 11:24:42 +0000 http://www.hindawi.com/journals/tswj/2014/986061/ Accurate indoor localization of mobile users is one of the challenging problems of the last decade. Besides delivering high speed Internet, Wireless Local Area Network (WLAN) can be used as an effective indoor positioning system, being competitive both in terms of accuracy and cost. Among the localization algorithms, nearest neighbor fingerprinting algorithms based on Received Signal Strength (RSS) parameter have been extensively studied as an inexpensive solution for delivering indoor Location Based Services (LBS). In this paper, we propose the optimization of the signal space distance parameters in order to improve precision of WLAN indoor positioning, based on nearest neighbor fingerprinting algorithms. Experiments in a real WLAN environment indicate that proposed optimization leads to substantial improvements of the localization accuracy. Our approach is conceptually simple, is easy to implement, and does not require any additional hardware. Milenko Brković and Mirjana Simić Copyright © 2014 Milenko Brković and Mirjana Simić. All rights reserved. Channel Estimation in DCT-Based OFDM Thu, 13 Mar 2014 09:11:32 +0000 http://www.hindawi.com/journals/tswj/2014/813429/ This paper derives the channel estimation of a discrete cosine transform- (DCT-) based orthogonal frequency-division multiplexing (OFDM) system over a frequency-selective multipath fading channel. Channel estimation has been proved to improve system throughput and performance by allowing for coherent demodulation. Pilot-aided methods are traditionally used to learn the channel response. Least square (LS) and mean square error estimators (MMSE) are investigated. We also study a compressed sensing (CS) based channel estimation, which takes the sparse property of wireless channel into account. Simulation results have shown that the CS based channel estimation is expected to have better performance than LS. However MMSE can achieve optimal performance because of prior knowledge of the channel statistic. Yulin Wang, Gengxin Zhang, Zhidong Xie, and Jing Hu Copyright © 2014 Yulin Wang et al. All rights reserved. A Fast Overlapping Community Detection Algorithm with Self-Correcting Ability Thu, 13 Mar 2014 08:18:45 +0000 http://www.hindawi.com/journals/tswj/2014/738206/ Due to the defects of all kinds of modularity, this paper defines a weighted modularity based on the density and cohesion as the new evaluation measurement. Since the proportion of the overlapping nodes in network is very low, the number of the nodes’ repeat visits can be reduced by signing the vertices with the overlapping attributes. In this paper, we propose three test conditions for overlapping nodes and present a fast overlapping community detection algorithm with self-correcting ability, which is decomposed into two processes. Under the control of overlapping properties, the complexity of the algorithm tends to be approximate linear. And we also give a new understanding on membership vector. Moreover, we improve the bridgeness function which evaluates the extent of overlapping nodes. Finally, we conduct the experiments on three networks with well known community structures and the results verify the feasibility and effectiveness of our algorithm. Laizhong Cui, Lei Qin, and Nan Lu Copyright © 2014 Laizhong Cui et al. All rights reserved. WDM Network and Multicasting Protocol Strategies Wed, 12 Mar 2014 11:28:27 +0000 http://www.hindawi.com/journals/tswj/2014/581052/ Optical technology gains extensive attention and ever increasing improvement because of the huge amount of network traffic caused by the growing number of internet users and their rising demands. However, with wavelength division multiplexing (WDM), it is easier to take the advantage of optical networks and optical burst switching (OBS) and to construct WDM networks with low delay rates and better data transparency these technologies are the best choices. Furthermore, multicasting in WDM is an urgent solution for bandwidth-intensive applications. In the paper, a new multicasting protocol with OBS is proposed. The protocol depends on a leaf initiated structure. The network is composed of source, ingress switches, intermediate switches, edge switches, and client nodes. The performance of the protocol is examined with Just Enough Time (JET) and Just In Time (JIT) reservation protocols. Also, the paper involves most of the recent advances about WDM multicasting in optical networks. WDM multicasting in optical networks is given as three common subtitles: Broadcast and-select networks, wavelength-routed networks, and OBS networks. Also, in the paper, multicast routing protocols are briefly summarized and optical burst switched WDM networks are investigated with the proposed multicast schemes. Pinar Kirci and Abdul Halim Zaim Copyright © 2014 Pinar Kirci and Abdul Halim Zaim. All rights reserved. Motion Adaptive Vertical Handoff in Cellular/WLAN Heterogeneous Wireless Network Tue, 11 Mar 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/341038/ In heterogeneous wireless network, vertical handoff plays an important role for guaranteeing quality of service and overall performance of network. Conventional vertical handoff trigger schemes are mostly developed from horizontal handoff in homogeneous cellular network. Basically, they can be summarized as hysteresis-based and dwelling-timer-based algorithms, which are reliable on avoiding unnecessary handoff caused by the terminals dwelling at the edge of WLAN coverage. However, the coverage of WLAN is much smaller compared with cellular network, while the motion types of terminals can be various in a typical outdoor scenario. As a result, traditional algorithms are less effective in avoiding unnecessary handoff triggered by vehicle-borne terminals with various speeds. Besides that, hysteresis and dwelling-timer thresholds usually need to be modified to satisfy different channel environments. For solving this problem, a vertical handoff algorithm based on Q-learning is proposed in this paper. Q-learning can provide the decider with self-adaptive ability for handling the terminals’ handoff requests with different motion types and channel conditions. Meanwhile, Neural Fuzzy Inference System (NFIS) is embedded to retain a continuous perception of the state space. Simulation results verify that the proposed algorithm can achieve lower unnecessary handoff probability compared with the other two conventional algorithms. Limin Li, Lin Ma, Yubin Xu, and Yunhai Fu Copyright © 2014 Limin Li et al. All rights reserved. MWAHCA: A Multimedia Wireless Ad Hoc Cluster Architecture Tue, 11 Mar 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/913046/ Wireless Ad hoc networks provide a flexible and adaptable infrastructure to transport data over a great variety of environments. Recently, real-time audio and video data transmission has been increased due to the appearance of many multimedia applications. One of the major challenges is to ensure the quality of multimedia streams when they have passed through a wireless ad hoc network. It requires adapting the network architecture to the multimedia QoS requirements. In this paper we propose a new architecture to organize and manage cluster-based ad hoc networks in order to provide multimedia streams. Proposed architecture adapts the network wireless topology in order to improve the quality of audio and video transmissions. In order to achieve this goal, the architecture uses some information such as each node’s capacity and the QoS parameters (bandwidth, delay, jitter, and packet loss). The architecture splits the network into clusters which are specialized in specific multimedia traffic. The real system performance study provided at the end of the paper will demonstrate the feasibility of the proposal. Juan R. Diaz, Jaime Lloret, Jose M. Jimenez, and Sandra Sendra Copyright © 2014 Juan R. Diaz et al. All rights reserved. A Novel Complex Networks Clustering Algorithm Based on the Core Influence of Nodes Mon, 10 Mar 2014 09:05:44 +0000 http://www.hindawi.com/journals/tswj/2014/801854/ In complex networks, cluster structure, identified by the heterogeneity of nodes, has become a common and important topological property. Network clustering methods are thus significant for the study of complex networks. Currently, many typical clustering algorithms have some weakness like inaccuracy and slow convergence. In this paper, we propose a clustering algorithm by calculating the core influence of nodes. The clustering process is a simulation of the process of cluster formation in sociology. The algorithm detects the nodes with core influence through their betweenness centrality, and builds the cluster’s core structure by discriminant functions. Next, the algorithm gets the final cluster structure after clustering the rest of the nodes in the network by optimizing method. Experiments on different datasets show that the clustering accuracy of this algorithm is superior to the classical clustering algorithm (Fast-Newman algorithm). It clusters faster and plays a positive role in revealing the real cluster structure of complex networks precisely. Chao Tong, Jianwei Niu, Bin Dai, and Zhongyu Xie Copyright © 2014 Chao Tong et al. All rights reserved. Modeling and Performance Analysis of an Improved Movement-Based Location Management Scheme for Packet-Switched Mobile Communication Systems Sun, 09 Mar 2014 15:28:36 +0000 http://www.hindawi.com/journals/tswj/2014/812657/ One of the key technologies to support mobility of mobile station (MS) in mobile communication systems is location management which consists of location update and paging. In this paper, an improved movement-based location management scheme with two movement thresholds is proposed, considering bursty data traffic characteristics of packet-switched (PS) services. The analytical modeling for location update and paging signaling loads of the proposed scheme is developed thoroughly and the performance of the proposed scheme is compared with that of the conventional scheme. We show that the proposed scheme outperforms the conventional scheme in terms of total signaling load with an appropriate selection of movement thresholds. Yun Won Chung, Jae Kyun Kwon, and Suwon Park Copyright © 2014 Yun Won Chung et al. All rights reserved. A Lightweight Neighbor-Info-Based Routing Protocol for No-Base-Station Taxi-Call System Sun, 09 Mar 2014 09:59:42 +0000 http://www.hindawi.com/journals/tswj/2014/601913/ Since the quick topology change and short connection duration, the VANET has had unstable routing and wireless signal quality. This paper proposes a kind of lightweight routing protocol-LNIB for call system without base station, which is applicable to the urban taxis. LNIB maintains and predicts neighbor information dynamically, thus finding the reliable path between the source and the target. This paper describes the protocol in detail and evaluates the performance of this protocol by simulating under different nodes density and speed. The result of evaluation shows that the performance of LNIB is better than AODV which is a classic protocol in taxi-call scene. Xudong Zhu, Jinhang Wang, and Yunchao Chen Copyright © 2014 Xudong Zhu et al. All rights reserved. Performance Analysis of Relay Subset Selection for Amplify-and-Forward Cognitive Relay Networks Thu, 06 Mar 2014 13:54:46 +0000 http://www.hindawi.com/journals/tswj/2014/548082/ Cooperative communication is regarded as a key technology in wireless networks, including cognitive radio networks (CRNs), which increases the diversity order of the signal to combat the unfavorable effects of the fading channels, by allowing distributed terminals to collaborate through sophisticated signal processing. Underlay CRNs have strict interference constraints towards the secondary users (SUs) active in the frequency band of the primary users (PUs), which limits their transmit power and their coverage area. Relay selection offers a potential solution to the challenges faced by underlay networks, by selecting either single best relay or a subset of potential relay set under different design requirements and assumptions. The best relay selection schemes proposed in the literature for amplify-and-forward (AF) based underlay cognitive relay networks have been very well studied in terms of outage probability (OP) and bit error rate (BER), which is deficient in multiple relay selection schemes. The novelty of this work is to study the outage behavior of multiple relay selection in the underlay CRN and derive the closed-form expressions for the OP and BER through cumulative distribution function (CDF) of the SNR received at the destination. The effectiveness of relay subset selection is shown through simulation results. Kiran Sultan, Ijaz Mansoor Qureshi, Aqdas Naveed Malik, and Muhammad Zubair Copyright © 2014 Kiran Sultan et al. All rights reserved. Energy-Efficient Routing Control Algorithm in Large-Scale WSN for Water Environment Monitoring with Application to Three Gorges Reservoir Area Wed, 05 Mar 2014 16:44:43 +0000 http://www.hindawi.com/journals/tswj/2014/802915/ The typical application backgrounds of large-scale WSN (wireless sensor networks) for the water environment monitoring in the Three Gorges Reservoir are large coverage area and wide distribution. To maximally prolong lifetime of large-scale WSN, a new energy-saving routing algorithm has been proposed, using the method of maximum energy-welfare optimization clustering. Firstly, temporary clusters are formed based on two main parameters, the remaining energy of nodes and the distance between a node and the base station. Secondly, the algorithm adjusts cluster heads and optimizes the clustering according to the maximum energy-welfare of the cluster by the cluster head shifting mechanism. Finally, in order to save node energy efficiently, cluster heads transmit data to the base station in single-hop and multihop way. Theoretical analysis and simulation results show that the proposed algorithm is feasible and advanced. It can efficiently save the node energy, balance the energy dissipation of all nodes, and prolong the network lifetime. Yuanchang Zhong, Lin Cheng, Liang Zhang, Yongduan Song, and Hamid Reza Karimi Copyright © 2014 Yuanchang Zhong et al. All rights reserved. Cooperative Search and Rescue with Artificial Fishes Based on Fish-Swarm Algorithm for Underwater Wireless Sensor Networks Wed, 05 Mar 2014 06:35:22 +0000 http://www.hindawi.com/journals/tswj/2014/145306/ This paper presents a searching control approach for cooperating mobile sensor networks. We use a density function to represent the frequency of distress signals issued by victims. The mobile nodes’ moving in mission space is similar to the behaviors of fish-swarm in water. So, we take the mobile node as artificial fish node and define its operations by a probabilistic model over a limited range. A fish-swarm based algorithm is designed requiring local information at each fish node and maximizing the joint detection probabilities of distress signals. Optimization of formation is also considered for the searching control approach and is optimized by fish-swarm algorithm. Simulation results include two schemes: preset route and random walks, and it is showed that the control scheme has adaptive and effective properties. Wei Zhao, Zhenmin Tang, Yuwang Yang, Lei Wang, and Shaohua Lan Copyright © 2014 Wei Zhao et al. All rights reserved. Bandwidth Enhancement of a Dual Band Planar Monopole Antenna Using Meandered Microstrip Feeding Mon, 03 Mar 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/856504/ A meandered-microstrip fed circular shaped monopole antenna loaded with vertical slots on a high dielectric material substrate is proposed in this paper. The performance criteria of the proposed antenna have been experimentally verified by fabricating a printed prototype. The experimental results show that the proposed antenna has achieved wider bandwidth with satisfactory gain by introducing meandered-microstrip feeding in assistant of partial ground plane. It is observed that, the −10 dB impedance bandwidth of the proposed antenna at lower band is 44.4% (600 MHz–1 GHz) and at upper band is 28% (2.25 GHz–2.95 GHz). The measured maximum gains of −1.18 dBi and 4.87 dBi with maximum radiation efficiencies have been observed at lower band and upper band, respectively. The antenna configuration and parametric study have been carried out with the help of commercially available computer-aided EM simulator, and a good accordance is perceived in between the simulated and measured results. The analysis of performance criteria and almost consistent radiation pattern make the proposed antenna a suitable candidate for UHF RFID, WiMAX, and WLAN applications. M. R. Ahsan, M. T. Islam, M. Habib Ullah, and N. Misran Copyright © 2014 M. R. Ahsan et al. All rights reserved. Design of a Compact Tuning Fork-Shaped Notched Ultrawideband Antenna for Wireless Communication Application Sun, 02 Mar 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/874241/ A new compact planar notched ultrawideband (UWB) antenna is designed for wireless communication application. The proposed antenna has a compact size of where is the wavelength of the lowest operating frequency. The antenna is comprised of rectangular radiating patch, ground plane, and an arc-shaped strip in between radiating patch and feed line. By introducing a new Tuning Fork-shaped notch in the radiating plane, a stopband is obtained. The antenna is tested and measured. The measured result indicated that fabricated antenna has achieved a wide bandwidth of 4.33–13.8 GHz (at −10 dB return loss) with a rejection frequency band of 5.28–6.97 GHz (WiMAX, WLAN, and C-band). The effects of the parameters of the antenna are discussed. The experiment results demonstrate that the proposed antenna can well meet the requirement for the UWB communication in spite of its compactness and small size. M. N. Shakib, M. Moghavvemi, and W. N. L. Mahadi Copyright © 2014 M. N. Shakib et al. All rights reserved. Protocol Independent Adaptive Route Update for VANET Thu, 27 Feb 2014 16:17:19 +0000 http://www.hindawi.com/journals/tswj/2014/403918/ High relative node velocity and high active node density have presented challenges to existing routing approaches within highly scaled ad hoc wireless networks, such as Vehicular Ad hoc Networks (VANET). Efficient routing requires finding optimum route with minimum delay, updating it on availability of a better one, and repairing it on link breakages. Current routing protocols are generally focused on finding and maintaining an efficient route, with very less emphasis on route update. Adaptive route update usually becomes impractical for dense networks due to large routing overheads. This paper presents an adaptive route update approach which can provide solution for any baseline routing protocol. The proposed adaptation eliminates the classification of reactive and proactive by categorizing them as logical conditions to find and update the route. Asim Rasheed, Sana Ajmal, and Amir Qayyum Copyright © 2014 Asim Rasheed et al. All rights reserved. Secure Wireless Communications via Cooperative Transmitting Sun, 23 Feb 2014 13:59:13 +0000 http://www.hindawi.com/journals/tswj/2014/760175/ Information-theoretic secrecy is combined with cryptographic secrecy to create a secret-key exchange protocol for wireless networks. A network of transmitters, which already have cryptographically secured channels between them, cooperate to exchange a secret key with a new receiver at a random location, in the presence of passive eavesdroppers at unknown locations. Two spatial point processes, homogeneous Poisson process and independent uniformly distributed points, are used for the spatial distributions of transmitters and eavesdroppers. We analyse the impact of the number of cooperating transmitters and the number of eavesdroppers on the area fraction where secure communication is possible. Upper bounds on the probability of existence of positive secrecy between the cooperating transmitters and the receiver are derived. The closeness of the upper bounds to the real value is then estimated by means of numerical simulations. Simulations also indicate that a deterministic spatial distribution for the transmitters, for example, hexagonal and square lattices, increases the probability of existence of positive secrecy capacity compared to the random spatial distributions. For the same number of friendly nodes, cooperative transmitting provides a dramatically larger secrecy region than cooperative jamming and cooperative relaying. Toni Draganov Stojanovski and Ninoslav Marina Copyright © 2014 Toni Draganov Stojanovski and Ninoslav Marina. All rights reserved. Channel Selection Based on Trust and Multiarmed Bandit in Multiuser, Multichannel Cognitive Radio Networks Sun, 23 Feb 2014 12:08:12 +0000 http://www.hindawi.com/journals/tswj/2014/916156/ This paper proposes a channel selection scheme for the multiuser, multichannel cognitive radio networks. This scheme formulates the channel selection as the multiarmed bandit problem, where cognitive radio users are compared to the players and channels to the arms. By simulation negotiation we can achieve the potential reward on each channel after it is selected for transmission; then the channel with the maximum accumulated rewards is formally chosen. To further improve the performance, the trust model is proposed and combined with multi-armed bandit to address the channel selection problem. Simulation results validate the proposed scheme. Fanzi Zeng and Xinwang Shen Copyright © 2014 Fanzi Zeng and Xinwang Shen. All rights reserved. Hybrid Single-Packet IP Traceback with Low Storage and High Accuracy Sun, 23 Feb 2014 10:02:35 +0000 http://www.hindawi.com/journals/tswj/2014/239280/ Traceback schemes have been proposed to trace the sources of attacks that usually hide by spoofing their IP addresses. Among these methods, schemes using packet logging can achieve single-packet traceback. But packet logging demands high storage on routers and therefore makes IP traceback impractical. For lower storage requirement, packet logging and packet marking are fused to make hybrid single-packet IP traceback. Despite such attempts, their storage still increases with packet numbers. That is why RIHT bounds its storage with path numbers to guarantee low storage. RIHT uses IP header’s ID and offset fields to mark packets, so it inevitably suffers from fragment and drop issues for its packet reassembly. Although the 16-bit hybrid IP traceback schemes, for example, MORE, can mitigate the fragment problem, their storage requirement grows up with packet numbers. To solve the storage and fragment problems in one shot, we propose a single-packet IP traceback scheme that only uses packets’ ID field for marking. Our major contributions are as follows: (1) our fragmented packets with tracing marks can be reassembled; (2) our storage is not affected by packet numbers; (3) it is the first hybrid single-packet IP traceback scheme to achieve zero false positive and zero false negative rates. Ming Hour Yang Copyright © 2014 Ming Hour Yang. All rights reserved. Design and Implementation of Low Profile Antenna for Dual-Band Applications Using Rotated E-Shaped Conductor-Backed Plane Sun, 23 Feb 2014 09:04:40 +0000 http://www.hindawi.com/journals/tswj/2014/632403/ A novel configuration of a printed monopole antenna with a very compact size for satisfying WLAN operations at the 5.2/5.8 GHz and also for X-band operations at the 10 GHz has been proposed. The antenna includes a simple square-shaped patch as the radiator, the rotated U-shaped conductor back plane element with embedded strip on it, and the partial rectangular ground surface. By using the rotated U-shaped conductor-backed plane with proper values, good impedance matching and improvement in bandwidth can be achieved, at the lower and upper bands. The impedance bandwidth for  dB is about 1.15 GHz for 5 GHz band and 5.3 GHz for X-band. The measured peak gains are about 1.9 dBi at WLAN-band and 4.2 dBi at X-band. The experimental results represent that the realized antenna with good omnidirectional radiation characteristics, enough impedance bandwidth, and reasonable gains can be appropriate for various applications of the future developed technologies and handheld devices. Mahdi Jalali, Tohid Sedghi, and Shahin Shafei Copyright © 2014 Mahdi Jalali et al. All rights reserved. A New Cooperative MIMO Scheme Based on SM for Energy-Efficiency Improvement in Wireless Sensor Network Thu, 20 Feb 2014 12:54:30 +0000 http://www.hindawi.com/journals/tswj/2014/975054/ Improving the energy efficiency in wireless sensor networks (WSN) has attracted considerable attention nowadays. The multiple-input multiple-output (MIMO) technique has been proved as a good candidate for improving the energy efficiency, but it may not be feasible in WSN which is due to the size limitation of the sensor node. As a solution, the cooperative multiple-input multiple-output (CMIMO) technique overcomes this constraint and shows a dramatically good performance. In this paper, a new CMIMO scheme based on the spatial modulation (SM) technique named CMIMO-SM is proposed for energy-efficiency improvement. We first establish the system model of CMIMO-SM. Based on this model, the transmission approach is introduced graphically. In order to evaluate the performance of the proposed scheme, a detailed analysis in terms of energy consumption per bit of the proposed scheme compared with the conventional CMIMO is presented. Later, under the guide of this new scheme we extend our proposed CMIMO-SM to a multihop clustered WSN for further achieving energy efficiency by finding an optimal hop-length. Equidistant hop as the traditional scheme will be compared in this paper. Results from the simulations and numerical experiments indicate that by the use of the proposed scheme, significant savings in terms of total energy consumption can be achieved. Combining the proposed scheme with monitoring sensor node will provide a good performance in arbitrary deployed WSN such as forest fire detection system. Yuyang Peng and Jaeho Choi Copyright © 2014 Yuyang Peng and Jaeho Choi. All rights reserved. Video Traffic Characteristics of Modern Encoding Standards: H.264/AVC with SVC and MVC Extensions and H.265/HEVC Thu, 20 Feb 2014 12:08:16 +0000 http://www.hindawi.com/journals/tswj/2014/189481/ Video encoding for multimedia services over communication networks has significantly advanced in recent years with the development of the highly efficient and flexible H.264/AVC video coding standard and its SVC extension. The emerging H.265/HEVC video coding standard as well as 3D video coding further advance video coding for multimedia communications. This paper first gives an overview of these new video coding standards and then examines their implications for multimedia communications by studying the traffic characteristics of long videos encoded with the new coding standards. We review video coding advances from MPEG-2 and MPEG-4 Part 2 to H.264/AVC and its SVC and MVC extensions as well as H.265/HEVC. For single-layer (nonscalable) video, we compare H.265/HEVC and H.264/AVC in terms of video traffic and statistical multiplexing characteristics. Our study is the first to examine the H.265/HEVC traffic variability for long videos. We also illustrate the video traffic characteristics and statistical multiplexing of scalable video encoded with the SVC extension of H.264/AVC as well as 3D video encoded with the MVC extension of H.264/AVC. Patrick Seeling and Martin Reisslein Copyright © 2014 Patrick Seeling and Martin Reisslein. All rights reserved. Uplink Scheduling and Adjacent-Channel Coupling Loss Analysis for TD-LTE Deployment Thu, 20 Feb 2014 09:09:49 +0000 http://www.hindawi.com/journals/tswj/2014/685102/ TD-LTE, one of the two duplexing modes in LTE, operates in unpaired spectrum and has the advantages of TDD-based technologies. It is expected that TD-LTE will be more rapidly deployed in near future and most of WiMax operators will upgrade their networks to TD-LTE gradually. Before completely upgrading to TD-LTE, WiMax may coexist with TD-LTE in an adjacent frequency band. In addition, multiple TD-LTE operators may deploy their networks in adjacent bands. When more than one TDD network operates in adjacent frequency bands, severe interference may happen due to adjacent channel interference (ACI) and unsynchronized operations. In this paper, coexistence issues between TD-LTE and other systems are analyzed and coexistence requirements are provided. This paper has three research objectives. First, frame synchronization between TD-LTE and WiMax is discussed by investigating possible combinations of TD-LTE and WiMax configurations. Second, an uplink scheduling algorithm is proposed to utilize a leakage pattern of ACI in synchronized operations. Third, minimum requirements for coexistence in unsynchronized operations are analyzed by introducing a concept of adjacent-channel coupling loss. From the analysis and simulation results, we can see that coexistence of TD-LTE with other TDD systems is feasible if the two networks are synchronized. For the unsynchronized case, some special cell-site engineering techniques may be required to reduce the ACI. Woon-Young Yeo, Sung Ho Moon, and Jae-Hoon Kim Copyright © 2014 Woon-Young Yeo et al. All rights reserved. Synthesis of Volumetric Ring Antenna Array for Terrestrial Coverage Pattern Tue, 18 Feb 2014 11:37:14 +0000 http://www.hindawi.com/journals/tswj/2014/260949/ This paper presents a synthesis of a volumetric ring antenna array for a terrestrial coverage pattern. This synthesis regards the spacing among the rings on the planes -, the positions of the rings on the plane -, and uniform and concentric excitations. The optimization is carried out by implementing the particle swarm optimization. The synthesis is compared with previous designs by resulting with proper performance of this geometry to provide an accurate coverage to be applied in satellite applications with a maximum reduction of the antenna hardware as well as the side lobe level reduction. Alberto Reyna, Marco A. Panduro, and Carlos Del Rio Bocio Copyright © 2014 Alberto Reyna et al. All rights reserved. Analysis and Modeling of Realistic Compound Channels in Transparent Relay Transmissions Tue, 18 Feb 2014 06:05:01 +0000 http://www.hindawi.com/journals/tswj/2014/538578/ Analytical approaches for the characterisation of the compound channels in transparent multihop relay transmissions over independent fading channels are considered in this paper. Compound channels with homogeneous links are considered first. Using Mellin transform technique, exact expressions are derived for the moments of cascaded Weibull distributions. Subsequently, two performance metrics, namely, coefficient of variation and amount of fade, are derived using the computed moments. These metrics quantify the possible variations in the channel gain and signal to noise ratio from their respective average values and can be used to characterise the achievable receiver performance. This approach is suitable for analysing more realistic compound channel models for scattering density variations of the environment, experienced in multihop relay transmissions. The performance metrics for such heterogeneous compound channels having distinct distribution in each hop are computed and compared with those having identical constituent component distributions. The moments and the coefficient of variation computed are then used to develop computationally efficient estimators for the distribution parameters and the optimal hop count. The metrics and estimators proposed are complemented with numerical and simulation results to demonstrate the impact of the accuracy of the approaches. Cibile K. Kanjirathumkal, Sameer S. Mohammed, and Lillykutty Jacob Copyright © 2014 Cibile K. Kanjirathumkal et al. All rights reserved. Reputation Revision Method for Selecting Cloud Services Based on Prior Knowledge and a Market Mechanism Mon, 17 Feb 2014 06:20:39 +0000 http://www.hindawi.com/journals/tswj/2014/617087/ The trust levels of cloud services should be evaluated to ensure their reliability. The effectiveness of these evaluations has major effects on user satisfaction, which is increasingly important. However, it is difficult to provide objective evaluations in open and dynamic environments because of the possibilities of malicious evaluations, individual preferences, and intentional praise. In this study, we propose a novel unfair rating filtering method for a reputation revision system. This method uses prior knowledge as the basis of similarity when calculating the average rating, which facilitates the recognition and filtering of unfair ratings. In addition, the overall performance is increased by a market mechanism that allows users and service providers to adjust their choice of services and service configuration in a timely manner. The experimental results showed that this method filtered unfair ratings in an effective manner, which greatly improved the precision of the reputation revision system. Qingtao Wu, Xulong Zhang, Mingchuan Zhang, Ying Lou, Ruijuan Zheng, and Wangyang Wei Copyright © 2014 Qingtao Wu et al. All rights reserved. Printed Wide-Slot Antenna Design with Bandwidth and Gain Enhancement on Low-Cost Substrate Thu, 13 Feb 2014 16:21:59 +0000 http://www.hindawi.com/journals/tswj/2014/804068/ This paper presents a printed wide-slot antenna design and prototyping on available low-cost polymer resin composite material fed by a microstrip line with a rotated square slot for bandwidth enhancement and defected ground structure for gain enhancement. An I-shaped microstrip line is used to excite the square slot. The rotated square slot is embedded in the middle of the ground plane, and its diagonal points are implanted in the middle of the strip line and ground plane. To increase the gain, four L-shaped slots are etched in the ground plane. The measured results show that the proposed structure retains a wide impedance bandwidth of 88.07%, which is 20% better than the reference antenna. The average gain is also increased, which is about 4.17 dBi with a stable radiation pattern in the entire operating band. Moreover, radiation efficiency, input impedance, current distribution, axial ratio, and parametric studies of S11 for different design parameters are also investigated using the finite element method-based simulation software HFSS. M. Samsuzzaman, M. T. Islam, J. S. Mandeep, and N. Misran Copyright © 2014 M. Samsuzzaman et al. All rights reserved. An Energy-Aware Routing Protocol for Query-Based Applications in Wireless Sensor Networks Thu, 13 Feb 2014 14:04:30 +0000 http://www.hindawi.com/journals/tswj/2014/359897/ Wireless sensor network (WSN) typically has energy consumption restriction. Designing energy-aware routing protocol can significantly reduce energy consumption in WSNs. Energy-aware routing protocols can be classified into two categories, energy savers and energy balancers. Energy saving protocols are used to minimize the overall energy consumed by a WSN, while energy balancing protocols attempt to efficiently distribute the consumption of energy throughout the network. In general terms, energy saving protocols are not necessarily good at balancing energy consumption and energy balancing protocols are not always good at reducing energy consumption. In this paper, we propose an energy-aware routing protocol (ERP) for query-based applications in WSNs, which offers a good trade-off between traditional energy balancing and energy saving objectives and supports a soft real time packet delivery. This is achieved by means of fuzzy sets and learning automata techniques along with zonal broadcasting to decrease total energy consumption. Ehsan Ahvar, Shohreh Ahvar, Gyu Myoung Lee, and Noel Crespi Copyright © 2014 Ehsan Ahvar et al. All rights reserved. An Empirical Evaluation of Lightweight Random Walk Based Routing Protocol in Duty Cycle Aware Wireless Sensor Networks Thu, 13 Feb 2014 13:13:13 +0000 http://www.hindawi.com/journals/tswj/2014/946249/ Energy efficiency is an important design paradigm in Wireless Sensor Networks (WSNs) and its consumption in dynamic environment is even more critical. Duty cycling of sensor nodes is used to address the energy consumption problem. However, along with advantages, duty cycle aware networks introduce some complexities like synchronization and latency. Due to their inherent characteristics, many traditional routing protocols show low performance in densely deployed WSNs with duty cycle awareness, when sensor nodes are supposed to have high mobility. In this paper we first present a three messages exchange Lightweight Random Walk Routing (LRWR) protocol and then evaluate its performance in WSNs for routing low data rate packets. Through NS-2 based simulations, we examine the LRWR protocol by comparing it with DYMO, a widely used WSN protocol, in both static and dynamic environments with varying duty cycles, assuming the standard IEEE 802.15.4 in lower layers. Results for the three metrics, that is, reliability, end-to-end delay, and energy consumption, show that LRWR protocol outperforms DYMO in scalability, mobility, and robustness, showing this protocol as a suitable choice in low duty cycle and dense WSNs. Adnan Noor Mian, Mehwish Fatima, Raees Khan, and Ravi Prakash Copyright © 2014 Adnan Noor Mian et al. All rights reserved. Cloud Service Selection Using Multicriteria Decision Analysis Thu, 13 Feb 2014 11:10:15 +0000 http://www.hindawi.com/journals/tswj/2014/459375/ Cloud computing (CC) has recently been receiving tremendous attention from the IT industry and academic researchers. CC leverages its unique services to cloud customers in a pay-as-you-go, anytime, anywhere manner. Cloud services provide dynamically scalable services through the Internet on demand. Therefore, service provisioning plays a key role in CC. The cloud customer must be able to select appropriate services according to his or her needs. Several approaches have been proposed to solve the service selection problem, including multicriteria decision analysis (MCDA). MCDA enables the user to choose from among a number of available choices. In this paper, we analyze the application of MCDA to service selection in CC. We identify and synthesize several MCDA techniques and provide a comprehensive analysis of this technology for general readers. In addition, we present a taxonomy derived from a survey of the current literature. Finally, we highlight several state-of-the-art practical aspects of MCDA implementation in cloud computing service selection. The contributions of this study are four-fold: (a) focusing on the state-of-the-art MCDA techniques, (b) highlighting the comparative analysis and suitability of several MCDA methods, (c) presenting a taxonomy through extensive literature review, and (d) analyzing and summarizing the cloud computing service selections in different scenarios. Md Whaiduzzaman, Abdullah Gani, Nor Badrul Anuar, Muhammad Shiraz, Mohammad Nazmul Haque, and Israat Tanzeena Haque Copyright © 2014 Md Whaiduzzaman et al. All rights reserved. Performance Analysis of MIMO-STBC Systems with Higher Coding Rate Using Adaptive Semiblind Channel Estimation Scheme Wed, 12 Feb 2014 12:19:51 +0000 http://www.hindawi.com/journals/tswj/2014/304901/ Semiblind channel estimation method provides the best trade-off in terms of bandwidth overhead, computational complexity and latency. The result after using multiple input multiple output (MIMO) systems shows higher data rate and longer transmit range without any requirement for additional bandwidth or transmit power. This paper presents the detailed analysis of diversity coding techniques using MIMO antenna systems. Different space time block codes (STBCs) schemes have been explored and analyzed with the proposed higher code rate. STBCs with higher code rates have been simulated for different modulation schemes using MATLAB environment and the simulated results have been compared in the semiblind environment which shows the improvement even in highly correlated antenna arrays and is found very close to the condition when channel state information (CSI) is known to the channel. Ravi Kumar and Rajiv Saxena Copyright © 2014 Ravi Kumar and Rajiv Saxena. All rights reserved. Low-Bit Rate Feedback Strategies for Iterative IA-Precoded MIMO-OFDM-Based Systems Tue, 11 Feb 2014 14:05:10 +0000 http://www.hindawi.com/journals/tswj/2014/619454/ Interference alignment (IA) is a promising technique that allows high-capacity gains in interference channels, but which requires the knowledge of the channel state information (CSI) for all the system links. We design low-complexity and low-bit rate feedback strategies where a quantized version of some CSI parameters is fed back from the user terminal (UT) to the base station (BS), which shares it with the other BSs through a limited-capacity backhaul network. This information is then used by BSs to perform the overall IA design. With the proposed strategies, we only need to send part of the CSI information, and this can even be sent only once for a set of data blocks transmitted over time-varying channels. These strategies are applied to iterative MMSE-based IA techniques for the downlink of broadband wireless OFDM systems with limited feedback. A new robust iterative IA technique, where channel quantization errors are taken into account in IA design, is also proposed and evaluated. With our proposed strategies, we need a small number of quantization bits to transmit and share the CSI, when comparing with the techniques used in previous works, while allowing performance close to the one obtained with perfect channel knowledge. Sara Teodoro, Adão Silva, Rui Dinis, and Atílio Gameiro Copyright © 2014 Sara Teodoro et al. All rights reserved. Augmented Lagrange Based on Modified Covariance Matching Criterion Method for DOA Estimation in Compressed Sensing Tue, 11 Feb 2014 13:23:48 +0000 http://www.hindawi.com/journals/tswj/2014/241469/ A novel direction of arrival (DOA) estimation method in compressed sensing (CS) is presented, in which DOA estimation is considered as the joint sparse recovery from multiple measurement vectors (MMV). The proposed method is obtained by minimizing the modified-based covariance matching criterion, which is acquired by adding penalties according to the regularization method. This minimization problem is shown to be a semidefinite program (SDP) and transformed into a constrained quadratic programming problem for reducing computational complexity which can be solved by the augmented Lagrange method. The proposed method can significantly improve the performance especially in the scenarios with low signal to noise ratio (SNR), small number of snapshots, and closely spaced correlated sources. In addition, the Cramér-Rao bound (CRB) of the proposed method is developed and the performance guarantee is given according to a version of the restricted isometry property (RIP). The effectiveness and satisfactory performance of the proposed method are illustrated by simulation results. Weijian Si, Xinggen Qu, and Lutao Liu Copyright © 2014 Weijian Si et al. All rights reserved. Design of Pulse Waveform for Waveform Division Multiple Access UWB Wireless Communication System Tue, 11 Feb 2014 11:48:17 +0000 http://www.hindawi.com/journals/tswj/2014/171875/ A new multiple access scheme, Waveform Division Multiple Access (WDMA) based on the orthogonal wavelet function, is presented. After studying the correlation properties of different categories of single wavelet functions, the one with the best correlation property will be chosen as the foundation for combined waveform. In the communication system, each user is assigned to different combined orthogonal waveform. Demonstrated by simulation, combined waveform is more suitable than single wavelet function to be a communication medium in WDMA system. Due to the excellent orthogonality, the bit error rate (BER) of multiuser with combined waveforms is so close to that of single user in a synchronous system. That is to say, the multiple access interference (MAI) is almost eliminated. Furthermore, even in an asynchronous system without multiuser detection after matched filters, the result is still pretty ideal and satisfactory by using the third combination mode that will be mentioned in the study. Zhendong Yin, Zhirui Wang, Xiaohui Liu, and Zhilu Wu Copyright © 2014 Zhendong Yin et al. All rights reserved. Integration and Analysis of Neighbor Discovery and Link Quality Estimation in Wireless Sensor Networks Tue, 11 Feb 2014 07:48:01 +0000 http://www.hindawi.com/journals/tswj/2014/789642/ Network connectivity and link quality information are the fundamental requirements of wireless sensor network protocols to perform their desired functionality. Most of the existing discovery protocols have only focused on the neighbor discovery problem, while a few number of them provide an integrated neighbor search and link estimation. As these protocols require a careful parameter adjustment before network deployment, they cannot provide scalable and accurate network initialization in large-scale dense wireless sensor networks with random topology. Furthermore, performance of these protocols has not entirely been evaluated yet. In this paper, we perform a comprehensive simulation study on the efficiency of employing adaptive protocols compared to the existing nonadaptive protocols for initializing sensor networks with random topology. In this regard, we propose adaptive network initialization protocols which integrate the initial neighbor discovery with link quality estimation process to initialize large-scale dense wireless sensor networks without requiring any parameter adjustment before network deployment. To the best of our knowledge, this work is the first attempt to provide a detailed simulation study on the performance of integrated neighbor discovery and link quality estimation protocols for initializing sensor networks. This study can help system designers to determine the most appropriate approach for different applications. Marjan Radi, Behnam Dezfouli, Kamalrulnizam Abu Bakar, and Shukor Abd Razak Copyright © 2014 Marjan Radi et al. All rights reserved. A New Subcarrier Allocation Strategy for MIMO-OFDMA Multicellular Networks Based on Cooperative Interference Mitigation Mon, 10 Feb 2014 10:28:45 +0000 http://www.hindawi.com/journals/tswj/2014/652968/ The goal of the study presented in this paper is to investigate the performance of a new subcarrier allocation strategy for Orthogonal Frequency Division Multiple Access (OFDMA) multicellular networks which employ Multiple Input Multiple Output (MIMO) architecture. For this reason, a hybrid system-link level simulator has been developed executing independent Monte Carlo (MC) simulations in parallel. Up to two tiers of cells around the central cell are taken into consideration and increased loading per cell. The derived results indicate that this strategy can provide up to 12% capacity gain for 16-QAM modulation and two tiers of cells around the central cell in a symmetric MIMO configuration. This gain is derived when comparing the proposed strategy to the traditional approach of allocating subcarriers that maximize only the desired user’s signal. Panagiotis K. Gkonis, Maria A. Seimeni, Nikolaos P. Asimakis, Dimitra I. Kaklamani, and Iakovos S. Venieris Copyright © 2014 Panagiotis K. Gkonis et al. All rights reserved. On the Degrees of Freedom of Interference Alignment for Multicell MIMO Interfering Broadcast Channels Mon, 10 Feb 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/827357/ The interference alignment (IA) is a promising technique to efficiently mitigate interference and to enhance capacity of a wireless network. This paper proposes an interference alignment scheme for a cellular network with L cells and K users under a multiple-input multiple-output (MIMO) Gaussian interfering broadcast channel (IFBC) scenario. The proposed IA scheme aligns intercell interferences (ICI) into a small dimensional subspace through a cooperative receive beamforming and cancels both the ICI and interuser interferences (IUI) simultaneously through a transmit beamforming. We characterize the feasibility condition for the proposed IA to achieve a total number of degrees of freedom (DoF) of LK in terms of the numbers of transmit antennas and receive antennas. Then we derive the maximum number of DoF achieved by the proposed IA by finding an optimal dimension of ICI alignment subspace for a given antenna configuration. The numerical results show that the proposed IA scheme has a better DoF performance than the conventional schemes. Hyun-Ho Choi Copyright © 2014 Hyun-Ho Choi. All rights reserved. Network Efficient Power Control for Wireless Communication Systems Sun, 09 Feb 2014 13:31:37 +0000 http://www.hindawi.com/journals/tswj/2014/650653/ We introduce a two-loop power control that allows an efficient use of the overall power resources for commercial wireless networks based on cross-layer optimization. This approach maximizes the network’s utility in the outer-loop as a function of the averaged signal to interference-plus-noise ratio (SINR) by considering adaptively the changes in the network characteristics. For this purpose, the concavity property of the utility function was verified with respect to the SINR, and an iterative search was proposed with guaranteed convergence. In addition, the outer-loop is in charge of selecting the detector that minimizes the overall power consumption (transmission and detection). Next the inner-loop implements a feedback power control in order to achieve the optimal SINR in the transmissions despite channel variations and roundtrip delays. In our proposal, the utility maximization process and detector selection and feedback power control are decoupled problems, and as a result, these strategies are implemented at two different time scales in the two-loop framework. Simulation results show that substantial utility gains may be achieved by improving the power management in the wireless network. Daniel U. Campos-Delgado, Jose Martin Luna-Rivera, C. J. Martinez-Sánchez, Carlos A. Gutierrez, and J. L. Tecpanecatl-Xihuitl Copyright © 2014 Daniel U. Campos-Delgado et al. All rights reserved. Error Analysis for RADAR Neighbor Matching Localization in Linear Logarithmic Strength Varying Wi-Fi Environment Sun, 09 Feb 2014 11:21:26 +0000 http://www.hindawi.com/journals/tswj/2014/647370/ This paper studies the statistical errors for the fingerprint-based RADAR neighbor matching localization with the linearly calibrated reference points (RPs) in logarithmic received signal strength (RSS) varying Wi-Fi environment. To the best of our knowledge, little comprehensive analysis work has appeared on the error performance of neighbor matching localization with respect to the deployment of RPs. However, in order to achieve the efficient and reliable location-based services (LBSs) as well as the ubiquitous context-awareness in Wi-Fi environment, much attention has to be paid to the highly accurate and cost-efficient localization systems. To this end, the statistical errors by the widely used neighbor matching localization are significantly discussed in this paper to examine the inherent mathematical relations between the localization errors and the locations of RPs by using a basic linear logarithmic strength varying model. Furthermore, based on the mathematical demonstrations and some testing results, the closed-form solutions to the statistical errors by RADAR neighbor matching localization can be an effective tool to explore alternative deployment of fingerprint-based neighbor matching localization systems in the future. Mu Zhou, Zengshan Tian, Kunjie Xu, Xiang Yu, and Haibo Wu Copyright © 2014 Mu Zhou et al. All rights reserved. Fault Tolerant Mobile Sensor Node Traversal Schemes Based on Hexagonal Coverage Thu, 06 Feb 2014 11:10:27 +0000 http://www.hindawi.com/journals/tswj/2014/130793/ Mobile sensor nodes (MSNs) are equipped with locomotive can move around after having been deployed. They are equipped with limited energy. A large portion of energy is drained during the traversal. In order to extend the life time of a MSN, the traveling distance must be minimized. Region of interest (ROI) is covered with multiple MSNs using coverage based pattern movement. When a group of MSNs are deployed to cover a given ROI, all the deployed MSNs should travel an approximately equal distance. Otherwise, the MSN which travels longer distance depletes more energy compared to the MSN which travels a shorter distance. In this work we show that, ROI partition plays great role in hole free coverage and makes the MSNs have optimized movement cost with fault tolerant support. Ganala Santoshi and R. J. D’Souza Copyright © 2014 Ganala Santoshi and R. J. D’Souza. All rights reserved. Data Delivery Method Based on Neighbor Nodes’ Information in a Mobile Ad Hoc Network Tue, 04 Feb 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/793171/ This paper proposes a data delivery method based on neighbor nodes’ information to achieve reliable communication in a mobile ad hoc network (MANET). In a MANET, it is difficult to deliver data reliably due to instabilities in network topology and wireless network condition which result from node movement. To overcome such unstable communication, opportunistic routing and network coding schemes have lately attracted considerable attention. Although an existing method that employs such schemes, MAC-independent opportunistic routing and encoding (MORE), Chachulski et al. (2007), improves the efficiency of data delivery in an unstable wireless mesh network, it does not address node movement. To efficiently deliver data in a MANET, the method proposed in this paper thus first employs the same opportunistic routing and network coding used in MORE and also uses the location information and transmission probabilities of neighbor nodes to adapt to changeable network topology and wireless network condition. The simulation experiments showed that the proposed method can achieve efficient data delivery with low network load when the movement speed is relatively slow. Shigeru Kashihara, Takuma Hayashi, Yuzo Taenaka, Takeshi Okuda, and Suguru Yamaguchi Copyright © 2014 Shigeru Kashihara et al. All rights reserved. Fabrication of CPW-Fed Fractal Antenna for UWB Applications with Omni-Directional Patterns Mon, 03 Feb 2014 11:40:38 +0000 http://www.hindawi.com/journals/tswj/2014/391602/ Novel and compact CPW-fed antennas are proposed comprised of a fractal patch and modified ground-plane. The ground-plane is truncated at the center and includes dielectric notches at its side to enhance the antenna’s impedance bandwidth. The dimensions of the notches effectively control the upper and lower band edges of the antenna. The optimized antenna operates across 2.95–12.81 GHz for  dB. Omnidirectional radiation pattern is achieved over the full UWB frequency range. The miniaturized antenna has a total size of  mm3. The characteristics of the proposed antenna are suitable for UWB wireless communication requiring low profile antennas. Tohid Sedghi, Mahdi Jalali, and Tohid Aribi Copyright © 2014 Tohid Sedghi et al. All rights reserved. QoS-Oriented High Dynamic Resource Allocation in Vehicular Communication Networks Thu, 30 Jan 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/718698/ Vehicular ad hoc networks (VANETs) are emerging as new research area and attracting an increasing attention from both industry and research communities. In this context, a dynamic resource allocation policy that maximizes the use of available resources and meets the quality of service (QoS) requirement of constraining applications is proposed. It is a combination of a fair packet scheduling policy and a new adaptive QoS oriented call admission control (CAC) scheme based on the vehicle density variation. This scheme decides whether the connection request is to be admitted into the system, while providing fair access and guaranteeing the desired throughput. The proposed algorithm showed good performance in testing in real world environment. Tarek Bejaoui Copyright © 2014 Tarek Bejaoui. All rights reserved. Coverage Extension and Balancing the Transmitted Power of the Moving Relay Node at LTE-A Cellular Network Wed, 29 Jan 2014 06:50:27 +0000 http://www.hindawi.com/journals/tswj/2014/815720/ The poor capacity at cell boundaries is not enough to meet the growing demand and stringent design which required high capacity and throughput irrespective of user’s location in the cellular network. In this paper, we propose new schemes for an optimum fixed relay node (RN) placement in LTE-A cellular network to enhance throughput and coverage extension at cell edge region. The proposed approach mitigates interferences between all nodes and ensures optimum utilization with the optimization of transmitted power. Moreover, we proposed a new algorithm to balance the transmitted power of moving relay node (MR) over cell size and providing required SNR and throughput at the users inside vehicle along with reducing the transmitted power consumption by MR. The numerical analysis along with the simulation results indicates that an improvement in capacity for users is 40% increment at downlink transmission from cell capacity. Furthermore, the results revealed that there is saving nearly 75% from transmitted power in MR after using proposed balancing algorithm. ATDI simulator was used to verify the numerical results, which deals with real digital cartographic and standard formats for terrain. Jaafar A. Aldhaibani, Abid Yahya, and R. Badlishah Ahmad Copyright © 2014 Jaafar A. Aldhaibani et al. All rights reserved. Augmented Twin-Nonlinear Two-Box Behavioral Models for Multicarrier LTE Power Amplifiers Wed, 29 Jan 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/762534/ A novel class of behavioral models is proposed for LTE-driven Doherty power amplifiers with strong memory effects. The proposed models, labeled augmented twin-nonlinear two-box models, are built by cascading a highly nonlinear memoryless function with a mildly nonlinear memory polynomial with cross terms. Experimental validation on gallium nitride based Doherty power amplifiers illustrates the accuracy enhancement and complexity reduction achieved by the proposed models. When strong memory effects are observed, the augmented twin-nonlinear two-box models can improve the normalized mean square error by up to 3 dB for the same number of coefficients when compared to state-of-the-art twin-nonlinear two-box models. Furthermore, the augmented twin-nonlinear two-box models lead to the same performance as previously reported twin-nonlinear two-box models while requiring up to 80% less coefficients. Oualid Hammi Copyright © 2014 Oualid Hammi. All rights reserved. Video Conferences through the Internet: How to Survive in a Hostile Environment Tue, 28 Jan 2014 07:53:20 +0000 http://www.hindawi.com/journals/tswj/2014/860170/ This paper analyzes and compares two different video conference solutions, widely used in corporate and home environments, with a special focus on the mechanisms used for adapting the traffic to the network status. The results show how these mechanisms are able to provide a good quality in the hostile environment of the public Internet, a best effort network without delay or delivery guarantees. Both solutions are evaluated in a laboratory, where different network impairments (bandwidth limit, delay, and packet loss) are set, in both the uplink and the downlink, and the reaction of the applications is measured. The tests show how these solutions modify their packet size and interpacket time, in order to increase or reduce the sent data. One of the solutions also uses a scalable video codec, able to adapt the traffic to the network status and to the end devices. Carlos Fernández, Jose Saldana, Julián Fernández-Navajas, Luis Sequeira, and Luis Casadesus Copyright © 2014 Carlos Fernández et al. All rights reserved. Design of Simplified Maximum-Likelihood Receivers for Multiuser CPM Systems Mon, 27 Jan 2014 14:02:22 +0000 http://www.hindawi.com/journals/tswj/2014/174294/ A class of simplified maximum-likelihood receivers designed for continuous phase modulation based multiuser systems is proposed. The presented receiver is built upon a front end employing mismatched filters and a maximum-likelihood detector defined in a low-dimensional signal space. The performance of the proposed receivers is analyzed and compared to some existing receivers. Some schemes are designed to implement the proposed receivers and to reveal the roles of different system parameters. Analysis and numerical results show that the proposed receivers can approach the optimum multiuser receivers with significantly (even exponentially in some cases) reduced complexity and marginal performance degradation. Li Bing and Baoming Bai Copyright © 2014 Li Bing and Baoming Bai. All rights reserved. Fault Tolerant Coverage and Connectivity in Presence of Channel Randomness Tue, 21 Jan 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/818135/ Some applications of wireless sensor network require -coverage and -connectivity to ensure the system to be fault tolerance and to make it more reliable. Therefore, it makes coverage and connectivity an important issue in wireless sensor networks. In this paper, we proposed -coverage and -connectivity models for wireless sensor networks. In both models, nodes are distributed according to Poisson distribution in the sensor field. To make the proposed model more realistic we used log-normal shadowing path loss model to capture the radio irregularities and studied its impact on -coverage and -connectivity. The value of can be different for different types of applications. Further, we also analyzed the problem of node failure for -coverage model. In the simulation section, results clearly show that coverage and connectivity of wireless sensor network depend on the node density, shadowing parameters like the path loss exponent, and standard deviation. Anil Kumar Sagar and D. K. Lobiyal Copyright © 2014 Anil Kumar Sagar and D. K. Lobiyal. All rights reserved. Optimal Throughput for Cognitive Radio with Energy Harvesting in Fading Wireless Channel Mon, 20 Jan 2014 12:55:11 +0000 http://www.hindawi.com/journals/tswj/2014/370658/ Energy resource management is a crucial problem of a device with a finite capacity battery. In this paper, cognitive radio is considered to be a device with an energy harvester that can harvest energy from a non-RF energy resource while performing other actions of cognitive radio. Harvested energy will be stored in a finite capacity battery. At the start of the time slot of cognitive radio, the radio needs to determine if it should remain silent or carry out spectrum sensing based on the idle probability of the primary user and the remaining energy in order to maximize the throughput of the cognitive radio system. In addition, optimal sensing energy and adaptive transmission power control are also investigated in this paper to effectively utilize the limited energy of cognitive radio. Finding an optimal approach is formulated as a partially observable Markov decision process. The simulation results show that the proposed optimal decision scheme outperforms the myopic scheme in which current throughput is only considered when making a decision. Hiep Vu-Van and Insoo Koo Copyright © 2014 Hiep Vu-Van and Insoo Koo. All rights reserved. Novel Wideband MIMO Antennas That Can Cover the Whole LTE Spectrum in Handsets and Portable Computers Thu, 16 Jan 2014 12:08:33 +0000 http://www.hindawi.com/journals/tswj/2014/694805/ A dual resonant antenna configuration is developed for multistandard multifunction mobile handsets and portable computers. Only two wideband resonant antennas can cover most of the LTE spectrums in portable communication equipment. The bandwidth that can be covered by each antenna exceeds 70% without using any matching or tuning circuits, with efficiencies that reach 80%. Thus, a dual configuration of them is capable of covering up to 39 LTE (4G) bands besides the existing 2G and 3G bands. MIMO configurations have been also developed for the two wideband antennas with a maximum isolation and a minimum correlation coefficient between the primary and the diversity antennas. Mohamed Sanad and Noha Hassan Copyright © 2014 Mohamed Sanad and Noha Hassan. All rights reserved. Hybrid Network Defense Model Based on Fuzzy Evaluation Thu, 16 Jan 2014 12:02:23 +0000 http://www.hindawi.com/journals/tswj/2014/178937/ With sustained and rapid developments in the field of information technology, the issue of network security has become increasingly prominent. The theme of this study is network data security, with the test subject being a classified and sensitive network laboratory that belongs to the academic network. The analysis is based on the deficiencies and potential risks of the network’s existing defense technology, characteristics of cyber attacks, and network security technologies. Subsequently, a distributed network security architecture using the technology of an intrusion prevention system is designed and implemented. In this paper, first, the overall design approach is presented. This design is used as the basis to establish a network defense model, an improvement over the traditional single-technology model that addresses the latter’s inadequacies. Next, a distributed network security architecture is implemented, comprising a hybrid firewall, intrusion detection, virtual honeynet projects, and connectivity and interactivity between these three components. Finally, the proposed security system is tested. A statistical analysis of the test results verifies the feasibility and reliability of the proposed architecture. The findings of this study will potentially provide new ideas and stimuli for future designs of network security architecture. Ying-Chiang Cho and Jen-Yi Pan Copyright © 2014 Ying-Chiang Cho and Jen-Yi Pan. All rights reserved. Low-Complexity User Selection for Rate Maximization in MIMO Broadcast Channels with Downlink Beamforming Thu, 16 Jan 2014 11:58:05 +0000 http://www.hindawi.com/journals/tswj/2014/865905/ We present in this work a low-complexity algorithm to solve the sum rate maximization problem in multiuser MIMO broadcast channels with downlink beamforming. Our approach decouples the user selection problem from the resource allocation problem and its main goal is to create a set of quasiorthogonal users. The proposed algorithm exploits physical metrics of the wireless channels that can be easily computed in such a way that a null space projection power can be approximated efficiently. Based on the derived metrics we present a mathematical model that describes the dynamics of the user selection process which renders the user selection problem into an integer linear program. Numerical results show that our approach is highly efficient to form groups of quasiorthogonal users when compared to previously proposed algorithms in the literature. Our user selection algorithm achieves a large portion of the optimum user selection sum rate (90%) for a moderate number of active users. Eduardo Castañeda, Adão Silva, Ramiro Samano-Robles, and Atílio Gameiro Copyright © 2014 Eduardo Castañeda et al. All rights reserved. Evaluation of Clipping Based Iterative PAPR Reduction Techniques for FBMC Systems Thu, 16 Jan 2014 10:05:06 +0000 http://www.hindawi.com/journals/tswj/2014/841680/ This paper investigates filter bankmulticarrier (FBMC), a multicarrier modulation technique exhibiting an extremely low adjacent channel leakage ratio (ACLR) compared to conventional orthogonal frequency division multiplexing (OFDM) technique. The low ACLR of the transmitted FBMC signal makes it especially favorable in cognitive radio applications, where strict requirements are posed on out-of-band radiation. Large dynamic range resulting in high peak-to-average power ratio (PAPR) is characteristic of all sorts of multicarrier signals. The advantageous spectral properties of the high-PAPR FBMC signal are significantly degraded if nonlinearities are present in the transceiver chain. Spectral regrowth may appear, causing harmful interference in the neighboring frequency bands. This paper presents novel clipping based PAPR reduction techniques, evaluated and compared by simulations and measurements, with an emphasis on spectral aspects. The paper gives an overall comparison of PAPR reduction techniques, focusing on the reduction of the dynamic range of FBMC signals without increasing out-of-band radiation. An overview is presented on transmitter oriented techniques employing baseband clipping, which can maintain the system performance with a desired bit error rate (BER). Zsolt Kollár, Lajos Varga, Bálint Horváth, Péter Bakki, and János Bitó Copyright © 2014 Zsolt Kollár et al. All rights reserved. Social Network Supported Process Recommender System Wed, 15 Jan 2014 15:20:49 +0000 http://www.hindawi.com/journals/tswj/2014/349065/ Process recommendation technologies have gained more and more attention in the field of intelligent business process modeling to assist the process modeling. However, most of the existing technologies only use the process structure analysis and do not take the social features of processes into account, while the process modeling is complex and comprehensive in most situations. This paper studies the feasibility of social network research technologies on process recommendation and builds a social network system of processes based on the features similarities. Then, three process matching degree measurements are presented and the system implementation is discussed subsequently. Finally, experimental evaluations and future works are introduced. Yanming Ye, Jianwei Yin, and Yueshen Xu Copyright © 2014 Yanming Ye et al. All rights reserved. Structured P2P Overlay of Mobile Brokers for Realizing Publish/Subscribe Communication in VANET Sun, 12 Jan 2014 11:39:48 +0000 http://www.hindawi.com/journals/tswj/2014/136365/ Publish/subscribe communication paradigm provides asynchrony and decoupling, making it an elegant alternative for designing applications in distributed and dynamic environment such as vehicular ad hoc networks (VANETs). In this paradigm, the broker is the most important component that decouples other two components, namely, publisher and subscriber. Previous research efforts have either utilized the deployment of distributed brokers on stationary road side info-stations or have assigned the role of broker to any moving vehicle on ad hoc basis. In one approach, lots of preinstalled infrastructures are needed whereas, in another, the quality of service is not guaranteed due to unpredictable moving and stopping patterns of vehicles. In this paper, we present the architecture of distributed mobile brokers which are dynamically reconfigurable in the form of structured P2P overlay and act as rendezvous points for matching publications and subscriptions. We have taken city buses in urban settings to act as mobile brokers whereas other vehicles are considered to be in role of publishers and subscribers. These mobile brokers also assist in locating a vehicle for successful and timely transfer of notifications. We have performed an extensive simulation study to compare our approach with previously proposed approaches. Simulation results establish the applicability of our approach. Tulika Pandey, Deepak Garg, and Manoj Madhava Gore Copyright © 2014 Tulika Pandey et al. All rights reserved. A Downlink and Uplink Alignment Scheme for Power Saving in IEEE 802.16 Protocol Sun, 12 Jan 2014 00:00:00 +0000 http://www.hindawi.com/journals/tswj/2014/217973/ This study shows the problem of power saving mechanism (PSM) that sleep intervals of uplink (UL) connections do not synchronize with sleep intervals of downlink (DL) connections. That is, the energy of a mobile station (MS) is not really saved if the DL connections are in the sleep mode while the UL connections are in normal mode, and vice versa. To avoid the asynchronism of power saving (PS) between UL and DL connections, we invent a mechanism of DL connections regulating UL connections, called DL and UL Alignment (DUAL) scheme, to improve the energy efficiency for PS. Considering that the buffer size of MS is limited, DUAL uses the mean packet arrival rate of UL and a relatively safe threshold of buffer size as the parameters to estimate the maximum allowable waiting time to align the UL with the DL connections. To analyze the performance of DUAL, a system model of PS is proposed to evaluate the performance of DUAL under different conditions. The correctness of performance analysis of DUAL is validated by using simulation with realistic parameters. Numerical experiments show that DUAL improves the energy conservation significantly when UL traffic is greater than DL traffic. Jenhui Chen, Woei-Hwa Tarn, and Jiann-Der Lee Copyright © 2014 Jenhui Chen et al. All rights reserved. Proactive Schema Based Link Lifetime Estimation and Connectivity Ratio Thu, 09 Jan 2014 14:02:40 +0000 http://www.hindawi.com/journals/tswj/2014/172014/ The radio link between a pair of wireless nodes is affected by a set of random factors such as transmission range, node mobility, and environment conditions. The properties of such radio links are continually experienced when nodes status balances between being reachable and being unreachable; thereby on completion of each experience the statistical distribution of link lifetime is updated. This aspect is emphasized in mobile ad hoc network especially when it is deployed in some fields that require intelligent processing of data information such as aerospace domain. Bouamoud Bachir, Ouacha Ali, Habbani Ahmed, and Elkoutbi Mohamed Copyright © 2014 Bouamoud Bachir et al. All rights reserved. Multiple Power-Saving MSSs Scheduling Methods for IEEE802.16e Broadband Wireless Networks Thu, 09 Jan 2014 08:52:22 +0000 http://www.hindawi.com/journals/tswj/2014/957158/ This work proposes two enhanced multiple mobile subscriber stations (MSSs) power-saving scheduling methods for IEEE802.16e broadband wireless networks. The proposed methods are designed for the Unsolicited Grant Service (UGS) of IEEE802.16e. To reduce the active periods of all power-saving MSSs, the base station (BS) allocates each MSS fewest possible transmission frames to retrieve its data from the BS. The BS interlaces the active periods of each MSS to increase the amount of scheduled MSSs and splits the overflowing transmission frames to maximize the bandwidth utilization. Simulation results reveal that interlacing the active periods of MSSs can increase the number of scheduled MSSs to more than four times of that in the Direct scheduling method. The bandwidth utilization can thus be improved by 60%–70%. Splitting the overflowing transmission frames can improve bandwidth utilization by more than 10% over that achieved using the method of interlacing active periods, with a sacrifice of only 1% of the sleep periods in the interlacing active period method. Shih-Chang Huang Copyright © 2014 Shih-Chang Huang. All rights reserved.