International Journal of Distributed Sensor Networks The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . All rights reserved. A Breakthrough in Multihop Wireless Multimedia Sensor Networking Protocols Thu, 26 Mar 2015 09:34:26 +0000 Byung-Seo Kim, Sung Won Kim, Chi Zhang, and Miao Pan Copyright © 2015 Byung-Seo Kim et al. All rights reserved. Verification and Validation of the Performance of WSN Thu, 26 Mar 2015 07:46:33 +0000 Seong-eun Yoo, Poh Kit Chong, Seong Hoon Kim, and Minh-Long Pham Copyright © 2015 Seong-eun Yoo et al. All rights reserved. Balance Transmission Mechanism in Underwater Acoustic Sensor Networks Wed, 25 Mar 2015 14:11:31 +0000 With the rapid development of underwater acoustic modem technology, underwater acoustic sensor networks (UWASNs) have more applications in long-term monitoring of the deployment area. In the underwater environment, the sensors are costly with limited energy. And acoustic communication medium poses new challenges, including high path loss, low bandwidth, and high energy consumption. Therefore, designing transmission mechanism to decrease energy consumption and to optimize the lifetime of UWASN becomes a significant task. This paper proposes a balance transmission mechanism, and divides the data transmission process into two phases. In the routing set-up phase, an efficient routing algorithm based on the optimum transmission distance is present to optimize the energy consumption of the UWASN. And then, a data balance transmission algorithm is introduced in the stable data transmission phase. The algorithm determines one-hop or multihop data transmission of the node to underwater sink according to the current energy level of adjacent nodes. Furthermore, detailed theoretical analysis evaluates the optimum energy levels in the UWASNs with different scales. The simulation results prove the efficiency of the BTM. Jiabao Cao, Jinfeng Dou, and Shunle Dong Copyright © 2015 Jiabao Cao et al. All rights reserved. Delay-Sensitive Routing Schemes for Underwater Acoustic Sensor Networks Wed, 25 Mar 2015 06:37:46 +0000 Underwater Acoustic Sensor Networks (UASNs) offer their practicable applications in seismic monitoring, sea mine detection, and disaster prevention. In these networks, fundamental difference between operational methodologies of routing schemes arises due to the requirement of time-critical applications; therefore, there is a need for the design of delay-sensitive techniques. In this paper, Delay-Sensitive Depth-Based Routing (DSDBR), Delay-Sensitive Energy Efficient Depth-Based Routing (DSEEDBR), and Delay-Sensitive Adaptive Mobility of Courier nodes in Threshold-optimized Depth-based routing (DSAMCTD) protocols are proposed to empower the depth-based routing schemes. The performance of the proposed schemes is validated in UASNs. All of the three schemes formulate delay-efficient Priority Factors (PF) and Delay-Sensitive Holding time () to minimize end-to-end delay with a small decrease in network throughput. These schemes also employ an optimal weight function () for the computation of transmission loss and speed of received signal. Furthermore, solution for delay lies in efficient data forwarding, minimal relative transmissions in low-depth region, and better forwarder selection. Simulations are performed to assess the proposed protocols and the results indicate that the three schemes largely minimize end-to-end delay along with improving the transmission loss of network. N. Javaid, M. R. Jafri, S. Ahmed, M. Jamil, Z. A. Khan, U. Qasim, and S. S. Al-Saleh Copyright © 2015 N. Javaid et al. All rights reserved. GRCBox: Extending Smartphone Connectivity in Vehicular Networks Mon, 23 Mar 2015 12:39:03 +0000 The low penetration of connectivity-enabled OBUs is delaying the deployment of vehicular networks (VNs) and therefore the development of vehicular delay tolerant network (VDTN) applications, among others. In this paper we present GRCBox, an architecture based on RaspberryPi that allows integrating smartphones in VNs. GRCBox is based on a low-cost device that combines several pieces of software to provide ad hoc and multi-interface connectivity to smartphones. Using GRCBox each application can choose the interface for its data flows, which increases flexibility and will allow developers to easily implement applications based on ad hoc connectivity, such as VDTN applications. Sergio M. Tornell, Subhadeep Patra, Carlos T. Calafate, Juan-Carlos Cano, and Pietro Manzoni Copyright © 2015 Sergio M. Tornell et al. All rights reserved. Ontologies for the Transactions on IoT Mon, 23 Mar 2015 09:38:12 +0000 To facilitate the efficient use of information generated from the Internet of Things (IoT) by sensors and automatically drive entities to meet the needs of human beings, this paper presents an information processing framework using semantic web technologies. The framework represents the entities as semantic web services and automatically creates service sequences as transactions by analyzing the information need in specific queries. Moreover, the framework ensures the effective management and control of information collected by mobile sensors during the transaction. The foundation of this framework lies in a set of ontologies we proposed: goal ontology, role ontology, constraint ontology, message ontology, status ontology, space-time ontology, and activity ontology. In addition to their respective definitions, we also present a detailed exploration of the relationships between them. Finally, we validate the effectiveness of the framework and the ontologies with a case study of the logistics system. The evaluation shows that the ontologies support the framework well and our approach increases the logistics system efficiency with lower operating costs. Chao Qu, Fagui Liu, and Ming Tao Copyright © 2015 Chao Qu et al. All rights reserved. Hybrid Indoor Human Localization System for Addressing the Issue of RSS Variation in Fingerprinting Mon, 23 Mar 2015 09:23:33 +0000 Indoor localization is used in many applications like security, healthcare, location based services, and social networking. Fingerprinting-based methods are widely used for indoor localization. But received signal strength (RSS) variation due to device diversity and change of conditions in the localization environment (e.g., distribution of furniture, people presence and movement, and opening and closing of doors) induce a significant localization error. To overcome this, we propose a hybrid indoor localization system using radio frequency (RF) and pyroelectric infrared (PIR) sensors. Our localization system has two stages. In the first stage, the zone of the target person is identified by PIR sensors. In the second stage, we apply K-nearest neighbor (K-NN) algorithm to the fingerprints within the zone identified and estimate position. Zone based processing of fingerprints will exclude deviated fingerprints because of RSS variation. We proposed two localization methods: Proposed_1 and Proposed_2 which use signal strength difference (SSD) and RSS, respectively. Simulation results show that the 0.8-meter accuracy of Proposed_1 achieves 84% and Proposed_2 achieves 65%, while traditional fingerprinting and SSD are 46% and 28%, respectively. Mekuanint Agegnehu Bitew, Rong-Shue Hsiao, Hsin-Piao Lin, and Ding-Bing Lin Copyright © 2015 Mekuanint Agegnehu Bitew et al. All rights reserved. An Analytical Approach to Relay Access Delay in Multihop Relay Chain of VANETs Mon, 23 Mar 2015 08:36:09 +0000 On the demand of many applications, vehicle to vehicle (V2V) communications have attracted many researchers’ attentions. In the developments of traffic safety applications based on VANET, the dissemination delay is critical. The dissemination delay of safety messages in the form of text has been studied thoroughly. In contrast, the dissemination delays of video or audio safety messages are just emerging and there are still a lot of things to be done. Considering the poor communication environment of multimedia safety messages dissemination in V2V, the analysis of multimedia message dissemination delay has great significance in the traffic safety applications. By extending and integrating previous achievements of analyzing MAC access delay in video stream dissemination, we proposed a method for modeling the relay access delay of IEEE 802.11p in the multihop relay chain of VANETs. Simulation results showed that the cumulative distribution function, the expectation, and the standard deviation of the relay access delays can be calculated effectively. In addition, the impacts of the number of hops and the length of packets on the relay access delays have been properly evaluated. Our study would open these research issues for discussion, which will contribute to the design and implementation of traffic safety. Dazhou Li and Hai Zhao Copyright © 2015 Dazhou Li and Hai Zhao. All rights reserved. A MAC Protocol for CR-WSN without a Dedicated Common Control Channel Sun, 22 Mar 2015 14:05:30 +0000 We present a decentralized medium access control protocol for cognitive radio wireless sensor networks. The proposed protocol allows secondary wireless sensors nodes to recognize spectrum opportunities and transmits data based on the licensed users’ arrival prediction on the channel. It estimates the number of active cognitive wireless sensor nodes and it also adjusts the sleep cycle in order to conserve energy. The proposed protocol does not need a dedicated common control channel to negotiate for the data channels. We evaluate delay, energy consumption, and goodput, which are the three important qualities of service parameters through simulation. The simulation results show that the proposed approach achieves higher energy conservation with a small cost of delay and adequate aggregated goodput. Gyanendra Prasad Joshi, Srijana Acharya, and Sung Won Kim Copyright © 2015 Gyanendra Prasad Joshi et al. All rights reserved. CMTG: A Content-Based Mobile Tendency Geocast Routing Protocol in Urban Vehicular Networks Sun, 22 Mar 2015 13:40:00 +0000 Efficient dissemination of messages is a vital solution to the vehicular communications and applications. Geocast, delivering messages to a few specific areas, has become an important issue with the accelerating development of the location-based services in vehicular networks. Different from the conventional geocast schemes focusing on the static target areas, in this paper, we propose a content-based mobile tendency geocast (CMTG) routing protocol for urban vehicular networks from the delay tolerant networks (DTNs) perspective to better deal with the high mobility and transient connectivity issues. The target roads of dissemination depend on the preferred tendency and path of message, based on the determination to the message’s expected propagating roads. And vehicle decides whether to relay the messages carried to other encountered vehicles by calculating the mobile tendency to the source location of message. The robustness and adaptability of protocol are also proved theoretically. Extensive performance comparisons with other protocols are conducted to show the advantages of CMTG. Haiquan Wang, Tao Zhu, Shuo Lei, Wenjing Yang, and Yu Wang Copyright © 2015 Haiquan Wang et al. All rights reserved. A Fast Handoff Scheme for Streaming Service in Wireless Sensor Networks Sun, 22 Mar 2015 13:21:01 +0000 The IEEE 802.15.4 standard is a rapidly growing technology for short-range communications and low rate Wireless personal area networking. The standard has been widely accepted as the de facto standard for wireless sensor network (WSN) because of its low cost deployment and remarkable applications. The mobility management in the existing WSN has highly suffered from different issues like high packet loss and delay because the current mobility management in IEEE 802.15.4 lacks the support of handover management for real-time streaming applications. In this paper, we propose a new fast handoff mechanism which eradicates the scanning delay. The proposed scheme uses the information of link quality (LQ) of the neighboring coordinators (COs), and on the basis of this information it selects an appropriate CO for handoff. The proposed scheme is evaluated through extensive simulations which show its strength and accuracy in the context of switching of high streaming data from one CO to another. Jeongbae Yun, Murad Khan, and Kijun Han Copyright © 2015 Jeongbae Yun et al. All rights reserved. A Voronoi-Based Location Privacy-Preserving Method for Continuous Query in LBS Sun, 22 Mar 2015 12:22:15 +0000 Most of the mobile phones have GPS sensors which make location based service (LBS) applicable. LBS brings not only convenience but also location privacy leak to us. Achieving anonymity and sending private queries are two main privacy-preserving courses in LBS. A novel location privacy-preserving method is proposed based on Voronoi graph partition on road networks. Firstly, based on the prediction of a user’s moving direction, a cooperative -anonymity method is proposed without constructing cloaking regions which may lead to efficiency decline in continuous query. And then, a query algorithm is proposed without providing any user's actual location, replaced by continuous anchor sequence, to LBS provider. This algorithm can work out precise results according to candidate sets returned by LBS provider and it also solves uneven distribution problem in SpaceTwist. Performance analysis and experiments show that our method achieves a preferable tradeoff between QoS and location privacy preserving; it has obvious advantages compared with other methods. Chunguang Ma, Changli Zhou, and Songtao Yang Copyright © 2015 Chunguang Ma et al. All rights reserved. Practical Link Duration Prediction Model in Vehicular Ad Hoc Networks Sun, 22 Mar 2015 11:28:44 +0000 Link duration prediction is one of the most fundamental problems in vehicular ad hoc networks (VANETs) as it determines the network performance of many vehicular applications. Existing analytical analysis about link duration in both mobile ad hoc network (MANETs) and VANETs is too complicated to be applied in a practical setting. Assuming vehicle’s velocity follows the normal distribution, we propose a practical model which considers the distribution of relative velocity, intervehicle distance, and impact of traffic lights to estimate the expected link duration between any pair of connected vehicles. Such model is implemented on each vehicle along with (1) a relative velocity estimation approach and (2) an exponential moving average- (EMA-) based data processing procedure. Furthermore, the proposed model assumes that the events of two consecutive vehicles encountering traffic lights combination are dependent, which make the model more practical. Simulation results show that the link duration model predicts link duration with the average accuracy of 10% and 20% in highway and city scenarios, respectively. Xiufeng Wang, Chunmeng Wang, Gang Cui, and Qing Yang Copyright © 2015 Xiufeng Wang et al. All rights reserved. BandEst: Measurement-Based Available Bandwidth Estimation and Flow Admission Control Algorithm for Ad Hoc IEEE 802.15.4-Based Wireless Multimedia Networks Sun, 22 Mar 2015 10:02:26 +0000 We highlight different important factors that must be considered for an effective available-bandwidth-based flow admission control algorithm in ad hoc wireless networks. Moreover, we present BandEst; it is a combination of a measurement-based available bandwidth estimation technique and a flow admission control algorithm for ad hoc IEEE 802.15.4-based ad hoc networks that considers the identified factors. Extensive simulations are performed to compare BandEst with the state-of-the-art available-bandwidth-based flow admission control algorithms for ad hoc wireless networks. Our simulation results demonstrate that BandEst significantly outperforms the state-of-the-art available-bandwidth-based flow admission control algorithms for ad hoc wireless networks. Muhammad Omer Farooq and Thomas Kunz Copyright © 2015 Muhammad Omer Farooq and Thomas Kunz. All rights reserved. Routing Protocols for Vehicular Delay Tolerant Networks: A Survey Sun, 22 Mar 2015 09:49:17 +0000 Recently, the delay tolerant networks (DTN) have been utilized in various operational communication paradigms. This includes the communication scenarios that are subject to disruption and disconnection as well as the scenarios with high delay and frequent partitioning, that is, vehicular ad hoc networks (VANETs). Due to the several characteristics match, new research paradigm named as vehicular delay tolerant networks (VDTNs) is introduced. Through relays and store-carry-forward mechanisms, messages in VDTNs can be delivered to the destination without an end-to-end connection for delay-tolerant applications. However, the choice of routing algorithms in VDTNs is still under study. The main objective of routing protocols in VDTNs is to maximize the probability of delivery at the destination while minimizing the end-to-end delay. Until now, many routing protocols have been proposed to meet requirements of varying applications. In this paper, we, therefore, provide a detailed study of recently proposed routing schemes for VDTNs. We also perform comparative analysis on the basis of unique criterion such as forwarding metrics with their implementations. In addition, open challenges and future directions are provided to make room of interest for the research community. Hyunwoo Kang, Syed Hassan Ahmed, Dongkyun Kim, and Yun-Su Chung Copyright © 2015 Hyunwoo Kang et al. All rights reserved. Performance Evaluation of a Real Vehicular Delay-Tolerant Network Testbed Sun, 22 Mar 2015 09:03:36 +0000 Vehicular Delay-Tolerant Networks (VDTNs) are a breakthrough based DTN solution used to provide vehicular communications under challenging scenarios, characterized by long delays and sporadic connections. Using the store-carry-and-forward paradigm, this technology allows in-transit bundles to asynchronously reach the destination hop by hop over traveling vehicles equipped with short-range wireless devices. The VDTN architecture assumes out-of-band signaling with control and data planes separation and follows an IP over VDTN approach. This paper presents a real-world VDTN prototype evaluated through a safety application and a Traffic Jam Information Service. It also demonstrates the real deployment of this new vehicular communication approach. The real testbed is an important contribution since some complex issues presented in vehicular communication systems can be studied more accurately in real-world environments than in a laboratory approach. The results confirm that real deployment of VDTNs is doable and can be seen as a very promising technology for vehicular communications, although it requires appropriated technologies for outline interferences and quality of service support. Maicke C. G. Paula, Joel J. P. C. Rodrigues, João A. Dias, João N. Isento, and Alexey Vinel Copyright © 2015 Maicke C. G. Paula et al. All rights reserved. Experimental Research Testbeds for Large-Scale WSNs: A Survey from the Architectural Perspective Thu, 19 Mar 2015 12:17:28 +0000 Wireless sensor networks (WSNs) have a significant potential in diverse applications. In contrast to WSNs in a small-scale setting, the real-world adoption of large-scale WSNs is quite slow particularly due to the lack of robustness of protocols at all levels. Upon the demanding need for their experimental verification and evaluation, researchers have developed numerous WSN testbeds. While each individual WSN testbed contributes to the progress with its own unique innovation, still a missing element is an analysis on the overall system architecture and methodologies that can lead to systematic advances. This paper seeks to provide a framework to reason about the evolving WSN testbeds from the architectural perspective. We define three core requirements for WSN testbeds, which are scalability, flexibility, and efficiency. Then, we establish a taxonomy of WSN testbeds that represents the architectural design space by a hierarchy of design domains and associated design approaches. Through a comprehensive literature survey of existing prominent WSN testbeds, we examine their best practices for each design approach in our taxonomy. Finally, we qualitatively evaluate WSN testbeds for their responsiveness to the aforementioned core requirements by assessing the influence by each design approach on the core requirements and suggest future directions of research. Hiecheol Kim, Won-Kee Hong, Joonhyuk Yoo, and Seong-eun Yoo Copyright © 2015 Hiecheol Kim et al. All rights reserved. A Survey from the Perspective of Evolutionary Process in the Internet of Things Thu, 19 Mar 2015 12:07:21 +0000 The title of this paper may suggest such topics as routing, networking, and data mining, but we focus on new research angles regarding the Internet of Things (IoT) as the theme of this paper. These research angles come from other disciplines and are in the process of being adopted by the IoT. Our paper serves a key purpose: from the perspective of correlative technologies based on time, to review the evolutionary process of the IoT and depict the relations between the correlation techniques which are largely missing in current literature in which the focus has been more on the introduction and comparison of existing technologies and less on issues describing evolutionary process of the IoT. We consider that the latter is crucial to understanding the evolution of the IoT. Through generalizations of particular focus in different stages of each technology, we can better understand the current phase of the IoT and therefore predict future challenges. This paper aims to bridge this gap by providing guidance in terms of the evolutionary process of the IoT and gives readers a panoramic view of the IoT field without repeating what is already available in existing literature so as to complement the existing IoT survey papers which have not covered the evolutionary process of the IoT. Feng Wang, Liang Hu, Jin Zhou, and Kuo Zhao Copyright © 2015 Feng Wang et al. All rights reserved. Management of Sensor-Related Data Based on Virtual TEDS in Sensing RFID System Thu, 19 Mar 2015 11:43:26 +0000 Integration of multiple sensors into active radio frequency identification (RFID) system is a technology trend. Currently, sensing RFID (SRFID) systems face a number of challenges including description of characteristics of nonsmart sensors, management of sensor-related data, and operational mechanism of sensor sampling. Based on transducer electronic data sheet (TEDS), this paper presents a virtual description method of nonsmart sensors integrated into the active RFID tag. The objective is to improve interoperability and compatibility of the sensing RFID system with off-the-shelf active RFID readers or novel sensing RFID open-loop systems in the future. This paper also proposes a data table storage mode for management of sensor-related data, in the system based on virtual TEDS. The paper analyses the operational mechanism and procedure of the sensor-sampling system that is equipped with these two proposed techniques. Several experiments were carried out with a newly developed container supply chain monitoring application system based on SRFID to examine the performance of the system. Wuming Luo, Miodrag Bolic, Jing Wang, and Xin Qian Copyright © 2015 Wuming Luo et al. All rights reserved. Evolutionary Game-Based Secrecy Rate Adaptation in Wireless Sensor Networks Wed, 18 Mar 2015 07:23:52 +0000 Physical layer security, whose aim is to maximize the secrecy rate of a source while keeping eavesdroppers ignorant of data transmitted, is extremely suitable for Wireless Sensor Networks (WSNs). We therefore, by developing the classical wire-tap channel, construct an approach to compute the secrecy rate between a sensor node and its responsible cluster head in the clustered WSNs. A noncooperative secrecy rate game towards WSNs is formulated to solve contradictions between maximizing the secrecy rate of a sensor node and minimizing power consumed for data transmission. Using evolutionary game theory, we set up a selection dynamics upon which a power level can be adaptively selected by a sensor node. Thus, the objective of secrecy rate adaptation for maximizing the fitness of member sensor nodes is achieved. We also prove the game is stable; that is, there exist evolutionarily stable strategies (ESSs) that explain which strategies will be selected by a sensor node in the end. Moreover, a corresponding algorithm of secrecy rate adaptation is given. Numerical experiments show our proposed approach can adaptively adjust the secrecy rate of a sensor node, which provides a novel way to guarantee the confidentiality of WSNs. Guanxiong Jiang, Shigen Shen, Keli Hu, Longjun Huang, Hongjie Li, and Risheng Han Copyright © 2015 Guanxiong Jiang et al. All rights reserved. A Machine Learning System for Routing Decision-Making in Urban Vehicular Ad Hoc Networks Wed, 18 Mar 2015 06:47:27 +0000 In vehicular ad hoc networks (VANETs), network topology and communication links frequently change due to the high mobility of vehicles. Key challenges include how to shorten transmission delays and increase the stability of transmissions. When establishing routing paths, most research focuses on detecting traffic and selecting roads with higher vehicle densities in order to transmit packets, thus avoiding carry-and-forward scenarios and decreasing transmission delays; however, such approaches may not obtain accurate real-time traffic densities by periodically monitoring each road because vehicle densities change so rapidly. In this paper, we propose a novel routing information system called the machine learning-assisted route selection (MARS) system to estimate necessary information for routing protocols. In MARS, road information is maintained in roadside units with the help of machine learning. We use machine learning to predict the moves of vehicles and then choose some suitable routing paths with better transmission capacity to transmit packets. Further, MARS can help to decide the forwarding direction between two RSUs according to the predicted location of the destination and the estimated transmission delays in both forwarding directions. Our proposed system can provide in-time routing information for VANETs and greatly enhance network performance. Wei Kuang Lai, Mei-Tso Lin, and Yu-Hsuan Yang Copyright © 2015 Wei Kuang Lai et al. All rights reserved. A Prediction Algorithm for Coexistence Problem in Multiple-WBAN Environment Mon, 16 Mar 2015 14:17:59 +0000 The coexistence problem occurs when a single wireless body area network (WBAN) is located within a multiple-WBAN environment. This causes WBANs to suffer from severe channel interference that degrades the communication performance of each WBAN. Since a WBAN handles vital signs that affect human life, the detection or prediction of coexistence condition is needed to guarantee reliable communication for each sensor node of a WBAN. Therefore, this paper presents a learning-based algorithm to efficiently predict the coexistence condition in a multiple-WBAN environment. The proposed algorithm jointly applies PRR and SINR, which are commonly used in wireless communication as a way to measure the quality of wireless connections. Our extensive simulation study using Castalia 3.2 simulator based on the OMNet++ platform shows that the proposed algorithm provides more reliable and accurate prediction than existing methods for detecting the coexistence problem in a multiple-WBAN environment. Zilong Jin, Yoonjeong Han, Jinsung Cho, and Ben Lee Copyright © 2015 Zilong Jin et al. All rights reserved. Bee-Sensor-C: An Energy-Efficient and Scalable Multipath Routing Protocol for Wireless Sensor Networks Thu, 12 Mar 2015 07:46:18 +0000 A wireless sensor network (WSN) is composed of a large collection of sensor nodes with limited resources in terms of battery supplied energy, processing capability, and storage. Therefore, the design of an energy-efficient and scalable routing protocol is a crucial concern for WSN applications. In this paper, we propose Bee-Sensor-C, an energy-aware and scalable multipath routing protocol based on dynamic cluster and foraging behavior of a bee swarm. Bee-Sensor-C is an evolution from BeeSensor which is a bee-inspired routing protocol for WSNs. First of all, through introducing a dynamic clustering scheme, Bee-Sensor-C offers parallel data transmissions close to the event area. This evolution reduces routing overhead and improves the scalability. Moreover, Bee-Sensor-C adopts an enhanced multipath construction method in order to achieve the balance of the network energy consumption. Besides, Bee-Sensor-C can well support the multicluster scenario. Through simulations, the network performance is evaluated and the results demonstrate that Bee-Sensor-C outperforms the existing protocols in terms of energy efficiency, energy consumption balance, packet delivery rate, and scalability. Xuelian Cai, Yulong Duan, Ying He, Jin Yang, and Changle Li Copyright © 2015 Xuelian Cai et al. All rights reserved. A Sleep Scheduling Mechanism with PSO Collaborative Evolution for Wireless Sensor Networks Wed, 11 Mar 2015 15:34:59 +0000 To extend the lifetime of a wireless sensor network and improve the energy efficiency of its nodes, it is necessary to use node collaborative sleep algorithm to reduce the number of redundant nodes in the network. This paper proposes a particle swarm optimization sleep scheduling mechanism for use in wireless sensor networks based on sleep scheduling algorithm. The mechanism adopts the approach of density control and finds the redundant nodes based on the computation results of the network coverage. Experimental results show that the proposed algorithm can ensure adequate coverage under the premise of the ability to close off the redundant nodes, while reducing the total energy consumption of the network. Luobing Dong, He Tao, William Doherty, and Marten Young Copyright © 2015 Luobing Dong et al. All rights reserved. Performance Evaluation of Localization Algorithms for WSNs Wed, 11 Mar 2015 13:28:54 +0000 In recent years, the use of wireless sensor networks has been increasing. Localization is a fundamental problem in wireless sensor networks (WSNs), since location information is essential for diverse applications such as tracking, quality network coverage, health, and energy efficiency. In this paper performance of localization algorithms such as range-free, range-based, and fuzzy-based decision is evaluated. We introduce a modification of an algorithm by providing weights to the correlation matrix to improve correctness. In all the cases the accuracy, precision, and computational complexity are evaluated as performance metrics. Location algorithms are evaluated using two scenarios, a first stage where all nodes are randomly distributed in a given area and a second scenario where four APs (access points) are placed on fixed positions and unknown nodes are randomly distributed within the sensing area. The received signal strength (RSS) is used to estimate the position of a node of interest. In the simulation results we show how our modified algorithm improves localization. On the other hand, we also have acceptable accuracy using distance-based algorithms, but they are more complex computationally. C. Vargas-Rosales, J. Mass-Sanchez, E. Ruiz-Ibarra, D. Torres-Roman, and A. Espinoza-Ruiz Copyright © 2015 C. Vargas-Rosales et al. All rights reserved. An Adaptive Linearized Method for Localizing Video Endoscopic Capsule Using Weighted Centroid Algorithm Tue, 10 Mar 2015 09:49:39 +0000 Video Capsule Endoscope (VCE) sends images of abnormalities in the gastrointestinal (GI) tract. While the physicians receive these images, they have little idea of their exact location which is needed for proper treatment. The proposed localization system consists of a 3D antenna array (with 8 receiver sensors) and one transmitter embedded inside the electronic capsule. We propose an adaptive linearized method of localization using Weighted Centroid Localization (WCL) where the position is calculated by averaging the weighted sum of the reference positions. In our proposed system, first we identify the path loss attenuation exponents using linear least square regression of the collected data (RSSI versus distance). Then the path loss model is linearized to minimize the path loss deviation which is mainly caused due to the nonhomogeneous environment of radio propagation. Then the instantaneous path loss (PL) measured by the sensors is attenuated to the above linearized model and considered as the weight of the sensors to find the location of the capsule using WCL. Finally a calibration process is applied using linear least square regression. To assess the performance, we model the path loss and implement the algorithm in Matlab for 2,530 possible positions with a resolution of 1 mm. The results show that the algorithm achieves high localization accuracy compared with other related methods when simulated using a 3D small intestine model. Umma Hany and Khan A. Wahid Copyright © 2015 Umma Hany and Khan A. Wahid. All rights reserved. Distributed Data Clustering via Opinion Dynamics Sun, 08 Mar 2015 09:46:41 +0000 We provide a distributed method to partition a large set of data in clusters, characterized by small in-group and large out-group distances. We assume a wireless sensors network in which each sensor is given a large set of data and the objective is to provide a way to group the sensors in homogeneous clusters by information type. In previous literature, the desired number of clusters must be specified a priori by the user. In our approach, the clusters are constrained to have centroids with a distance at least between them and the number of desired clusters is not specified. Although traditional algorithms fail to solve the problem with this constraint, it can help obtain a better clustering. In this paper, a solution based on the Hegselmann-Krause opinion dynamics model is proposed to find an admissible, although suboptimal, solution. The Hegselmann-Krause model is a centralized algorithm; here we provide a distributed implementation, based on a combination of distributed consensus algorithms. A comparison with -means algorithm concludes the paper. Gabriele Oliva, Damiano La Manna, Adriano Fagiolini, and Roberto Setola Copyright © 2015 Gabriele Oliva et al. All rights reserved. Bio-Inspired Mechanisms in Wireless Sensor Networks Sun, 08 Mar 2015 06:49:39 +0000 S. Khan, Jaime Lloret, and Elsa Macias-López Copyright © 2015 S. Khan et al. All rights reserved. Boosting VoIP Capacity via Service Differentiation in IEEE 802.11e EDCA Networks Thu, 05 Mar 2015 13:53:56 +0000 This paper considers the performance problem of VoIP over 802.11e WLANs caused by the unfairness between uplink and downlink as well as the inefficient EDCA. A novel medium access control scheme named BEDCA (Balanced EDCA) is presented, which provides service differentiation between the access point (AP) and the mobile stations (STAs) to enhance VoIP capacity. In BEDCA, the expression of AP’s contention window is obtained which is a relative constant value independent of the participating STAs. The minimum contention window of the STAs is traffic-aware based on the proposed algorithm. The performance improvement of BEDCA is verified through intensive simulations and the results show the capacity improvement of 82.1% compared to EDCA. Pingping Dong, Jianxin Wang, Haodong Wang, and Yi Pan Copyright © 2015 Pingping Dong et al. All rights reserved. A Model-Driven Engineering Process for Autonomic Sensor-Actuator Networks Thu, 05 Mar 2015 13:27:13 +0000 Cyber-Physical Systems (CPS) are the next generation of embedded ICT systems designed to be aware of the physical environment by using sensor-actuator networks to provide users with a wide range of smart applications and services. Many of these smart applications are possible due to the incorporation of autonomic control loops that implement advanced processing and analysis of historical and real-time data measured by sensors; plan actions according to a set of goals or policies; and execute plans through actuators. The complexity of this kind of systems requires mechanisms that can assist the system’s design and development. This paper presents a solution for assisting the design and development of CPS based on Model-Driven Development: MindCPS (doMaIN moDel for CPS) solution. MindCPS solution is based on a model that provides modelling primitives for explicitly specifying the autonomic behaviour of CPS and model transformations for automatically generating part of the CPS code. In addition to the automatic code generation, the MindCPS solution offers the possibility of rapidly configuring and developing the core behaviour of a CPS, even for nonsoftware engineers. The MindCPS solution has been put into practice to deploy a smart metering system in a demonstrator located at the Technical University of Madrid. Carlos Vidal, Carlos Fernández-Sánchez, Jessica Díaz, and Jennifer Pérez Copyright © 2015 Carlos Vidal et al. All rights reserved.