Journal of Computer Networks and Communications The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. A Mechanically Proved and an Incremental Development of the Session Initiation Protocol INVITE Transaction Wed, 19 Nov 2014 09:29:17 +0000 The Session Initiation Protocol (SIP) is an application layer signaling protocol used to create, manage, and terminate sessions in an IP based network. SIP is considered as a transactional protocol. There are two main SIP transactions, the INVITE transaction and the non-INVITE transaction. The SIP INVITE transaction specification is described in an informal way in Request for Comments (RFC) 3261 and modified in RFC 6026. In this paper we focus on the INVITE transaction of SIP, over reliable and unreliable transport mediums, which is used to initiate a session. In order to ensure the correctness of SIP, the INVITE transaction is modeled and verified using event-B method and its Rodin platform. The Event-B refinement concept allows an incremental development by defining the studied system at different levels of abstraction, and Rodin discharges almost all proof obligations at each level. This interaction between modeling and proving reduces the complexity and helps in assuring that the INVITE transaction SIP specification is correct, unambiguous, and easy to understand. Rajaa Filali and Mohamed Bouhdadi Copyright © 2014 Rajaa Filali and Mohamed Bouhdadi. All rights reserved. Estimation and Statistical Analysis of Human Voice Parameters to Investigate the Influence of Psychological Stress and to Determine the Vocal Tract Transfer Function of an Individual Tue, 18 Nov 2014 11:44:20 +0000 In this study the principal focus is to examine the influence of psychological stress (both positive and negative stress) on the human articulation and to determine the vocal tract transfer function of an individual using inverse filtering technique. Both of these analyses are carried out by estimating various voice parameters. The outcomes of the analysis of psychological stress indicate that all the voice parameters are affected due to the influence of stress on humans. About 35 out of 51 parameters follow a unique course of variation from normal to positive and negative stress in 32% of the total analyzed signals. The upshot of the analysis is to determine the vocal tract transfer function for each vowel for an individual. The analysis indicates that it can be computed by estimating the mean of the pole zero plots of that individual’s vocal tract estimated for the whole day. Besides this, an analysis is presented to find the relationship between the LPC coefficients of the vocal tract and the vocal tract cavities. The results of the analysis indicate that all the LPC coefficients of the vocal tract are affected due to change in the position of any cavity. Puneet Kumar Mongia and R. K. Sharma Copyright © 2014 Puneet Kumar Mongia and R. K. Sharma. All rights reserved. QoS-Based Web Service Discovery in Mobile Ad Hoc Networks Using Swarm Strategies Mon, 10 Nov 2014 12:03:02 +0000 Mobile ad hoc networks are noncentralised, multihop, wireless networks that lack a common infrastructure and hence require self-organisation. Their infrastructureless and dynamic nature entails the implementation of a new set of networking technologies in order to provide efficient end-to-end communication according to the principles of the standard TCP/IP suite. Routing, IP address autoconfiguration and Web service discovery are among the most challenging tasks in the ad hoc network domain. Swarm intelligence is a relatively new approach to problem solving that takes inspiration from the social behaviours of insects, such as ants and bees. Self-organization, decentralization, adaptivity, robustness, and scalability make swarm intelligence a successful design paradigm for the above-mentioned problems. In this paper we propose BeeAdHocServiceDiscovery, a new service discovery algorithm based on the bee metaphor, which also takes into account quality metrics estimates. The protocol has been specifically designed to work in mobile ad hoc network scenarios operating with Beeadhoc, a well-known routing algorithm inspired by nature. We present both the protocol strategy and the formal evaluation of the discovery overhead and route optimality metrics showing that BeeAdHocServiceDiscovery guarantees valuable performances even in large scale ad hoc wireless networks. Eventually, future research suggestions are sketched. Filomena de Santis and Delfina Malandrino Copyright © 2014 Filomena de Santis and Delfina Malandrino. All rights reserved. Packet Payload Monitoring for Internet Worm Content Detection Using Deterministic Finite Automaton with Delayed Dictionary Compression Mon, 10 Nov 2014 00:00:00 +0000 Packet content scanning is one of the crucial threats to network security and network monitoring applications. In monitoring applications, payload of packets in a network is matched against the set of patterns in order to detect attacks like worms, viruses, and protocol definitions. During network transfer, incoming and outgoing packets are monitored in depth to inspect the packet payload. In this paper, the regular expressions that are basically string patterns are analyzed for packet payloads in detecting worms. Then the grouping scheme for regular expression matching is rewritten using Deterministic Finite Automaton (DFA). DFA achieves better processing speed during regular expression matching. DFA requires more memory space for each state. In order to reduce memory utilization, decompression technique is used. Delayed Dictionary Compression (DDC) is applied for achieving better speeds in the communication links. DDC achieves decoding latency during compression of payload packets in the network. Experimental results show that the proposed approach provides better time consumption and memory utilization during detection of Internet worm attacks. Divya Selvaraj and Padmavathi Ganapathi Copyright © 2014 Divya Selvaraj and Padmavathi Ganapathi. All rights reserved. Fuzzy-Based Adaptive Hybrid Burst Assembly Technique for Optical Burst Switched Networks Mon, 03 Nov 2014 07:33:47 +0000 The optical burst switching (OBS) paradigm is perceived as an intermediate switching technology for future all-optical networks. Burst assembly that is the first process in OBS is the focus of this paper. In this paper, an intelligent hybrid burst assembly algorithm that is based on fuzzy logic is proposed. The new algorithm is evaluated against the traditional hybrid burst assembly algorithm and the fuzzy adaptive threshold (FAT) burst assembly algorithm via simulation. Simulation results show that the proposed algorithm outperforms the hybrid and the FAT algorithms in terms of burst end-to-end delay, packet end-to-end delay, and packet loss ratio. Abubakar Muhammad Umaru, Muhammad Shafie Abd Latiff, and Yahaya Coulibaly Copyright © 2014 Abubakar Muhammad Umaru et al. All rights reserved. Energy-Efficient Cluster Based Routing Protocol in Mobile Ad Hoc Networks Using Network Coding Thu, 23 Oct 2014 00:00:00 +0000 In mobile ad hoc networks, all nodes are energy constrained. In such situations, it is important to reduce energy consumption. In this paper, we consider the issues of energy efficient communication in MANETs using network coding. Network coding is an effective method to improve the performance of wireless networks. COPE protocol implements network coding concept to reduce number of transmissions by mixing the packets at intermediate nodes. We incorporate COPE into cluster based routing protocol to further reduce the energy consumption. The proposed energy-efficient coding-aware cluster based routing protocol (ECCRP) scheme applies network coding at cluster heads to reduce number of transmissions. We also modify the queue management procedure of COPE protocol to further improve coding opportunities. We also use an energy efficient scheme while selecting the cluster head. It helps to increase the life time of the network. We evaluate the performance of proposed energy efficient cluster based protocol using simulation. Simulation results show that the proposed ECCRP algorithm reduces energy consumption and increases life time of the network. Srinivas Kanakala, Venugopal Reddy Ananthula, and Prashanthi Vempaty Copyright © 2014 Srinivas Kanakala et al. All rights reserved. Use of Attack Graphs in Security Systems Mon, 20 Oct 2014 11:15:20 +0000 Attack graphs have been used to model the vulnerabilities of the systems and their potential exploits. The successful exploits leading to the partial/total failure of the systems are subject of keen security interest. Considerable effort has been expended in exhaustive modeling, analyses, detection, and mitigation of attacks. One prominent methodology involves constructing attack graphs of the pertinent system for analysis and response strategies. This not only gives the simplified representation of the system, but also allows prioritizing the security properties whose violations are of greater concern, for both detection and repair. We present a survey and critical study of state-of-the-art technologies in attack graph generation and use in security system. Based on our research, we identify the potential, challenges, and direction of the current research in using attack graphs. Vivek Shandilya, Chris B. Simmons, and Sajjan Shiva Copyright © 2014 Vivek Shandilya et al. All rights reserved. Edge-Disjoint Fibonacci Trees in Hypercube Sun, 19 Oct 2014 11:34:00 +0000 The Fibonacci tree is a rooted binary tree whose number of vertices admit a recursive definition similar to the Fibonacci numbers. In this paper, we prove that a hypercube of dimension admits two edge-disjoint Fibonacci trees of height , two edge-disjoint Fibonacci trees of height , two edge-disjoint Fibonacci trees of height and so on, as subgraphs. The result shows that an algorithm with Fibonacci trees as underlying data structure can be implemented concurrently on a hypercube network with no communication latency. Indhumathi Raman and Lakshmanan Kuppusamy Copyright © 2014 Indhumathi Raman and Lakshmanan Kuppusamy. All rights reserved. TETRA Backhauling via Satellite: Improving Call Setup Times and Saving Bandwidth Thu, 16 Oct 2014 14:08:17 +0000 In disaster management scenarios with seriously damaged, not existing, or saturated communication infrastructures satellite communications can be an ideal means to provide connectivity with unaffected remote terrestrial trunked radio (TETRA) core networks. However, the propagation delay imposed by the satellite link affects the signalling protocols. This paper discusses the suitability of using a satellite link for TETRA backhauling, introducing two different architectures. In order to cope with the signal delay of the satellite link, the paper proposes and analyzes a suitable solution based on the use of a performance enhancing proxy (PEP). Additionally, robust header compression (ROHC) is discussed as suitable technology to transmit TETRA voice via IP-based satellite networks. Anton Donner, Jawad Ahmed Saleemi, and Javier Mulero Chaves Copyright © 2014 Anton Donner et al. All rights reserved. Miniaturized CPW-Fed Triband Antenna with Asymmetric Ring for WLAN/WiMAX Applications Thu, 16 Oct 2014 11:41:55 +0000 A compact CPW-fed triband slot antenna for WLAN/WiMAX applications is proposed. The proposed antenna is formed by an asymmetric ring, an inverted L-strip, and a straight strip. By employing these structures, the antenna can generate three operation bands with compact size and simple structure. The measured and simulated results show the presented antenna has impedance bandwidths of 100 MHz (2.39–2.49 GHz), 360 MHz (3.36–3.72 GHz), and 760 MHz (5.13–5.89 GHz), which covers both WLAN in the 2.4/5.2 GHz bands and WiMAX in the 3.5/5.5 GHz bands. The antenna is successfully simulated and measured, showing triple bands can be obtained by using three different radiators and also indicating that the proposed antenna is suitable for the WiMAX/WLAN applications. Shanshan Huang, Jun Li, and Jianzhong Zhao Copyright © 2014 Shanshan Huang et al. All rights reserved. Implementation of Special Function Unit for Vertex Shader Processor Using Hybrid Number System Wed, 15 Oct 2014 08:48:21 +0000 The world of 3D graphic computing has undergone a revolution in the recent past, making devices more computationally intensive, providing high-end imaging to the user. The OpenGL ES Standard documents the requirements of graphic processing unit. A prime feature of this standard is a special function unit (SFU), which performs all the required mathematical computations on the vertex information corresponding to the image. This paper presents a low-cost, high-performance SFU architecture with improved speed and reduced area. Hybrid number system is employed here in order to reduce the complexity of operations by suitably switching between logarithmic number system (LNS) and binary number system (BNS). In this work, reduction of area and a higher operating frequency are achieved with almost the same power consumption as that of the existing implementations. Avni Agarwal, P. Harsha, Swati Vasishta, and S. Sivanantham Copyright © 2014 Avni Agarwal et al. All rights reserved. Efficient Priority Access to the Shared Commercial Radio with Offloading for Public Safety in LTE Heterogeneous Networks Sun, 12 Oct 2014 08:17:06 +0000 This paper presents the algorithm Courteous Priority Access to the shared commercial radio with offloading (CPAwO), for public safety network (PSN) over LTE heterogeneous networks (HetNets). We propose a solution for prioritization of PSN users with access to the commercial radio network resources. Our model offers additional radio resources to the PSN. Furthermore, it ensures a certain priority for commercial users by assigning quantities of additional radio resources through the courteous scheme. This allows delaying preemption and blocking bearers when the radio resources are limited. The other part of CPAwO model is to apply the principle of offloading in order to reduce the impact of the macrocell congestion. This technique is to switch the new bearers arriving at the LTE macrocells to small cells, in order to decrease the number of the blocked and interrupted bearers in the network. The results of the simulation showed that the allocation of radio resources via the courteous mechanism with offloading of new bearers to small cells reduces the rate of blocking bearers and delays the preemption of active bearers present in the LTE HetNets. It also reduces the cost of the end-to-end communications, thanks to the reallocation of free frequencies. Chafika Tata and Michel Kadoch Copyright © 2014 Chafika Tata and Michel Kadoch. All rights reserved. A New QoS Management Scheme for VoIP Application over Wireless Ad Hoc Networks Tue, 07 Oct 2014 11:37:00 +0000 Nowadays, mobile ad hoc networks (MANETs) have to support new applications including VoIP (voice over IP) that impose stringent QoS (quality of service) constraints and requirements. However, VoIP applications make a very inefficient use of the MANET resources. Our work represents a first step toward improving aspects at the network layer by addressing issues from the standpoint of adaptation, claiming that effective adaptation of routing parameters can enhance VoIP quality. The most important contribution is the adaptive OLSR-VA algorithm which provides an integrated environment where VoIP activity is constantly detected and routing parameters are adapted in order to meet the application requirements. To investigate the performance advantage achieved by such algorithm, a number of realistic simulations (MANET scenarios) are performed under different conditions. The most important observation is that performance is satisfactory in terms of the perceived voice quality. Said El brak, Mohamed El brak, and Driss Benhaddou Copyright © 2014 Said El brak et al. All rights reserved. Hole Detection for Quantifying Connectivity in Wireless Sensor Networks: A Survey Tue, 07 Oct 2014 09:25:48 +0000 Owing to random deployment, environmental factors, dynamic topology, and external attacks, emergence of holes in wireless sensor networks is inescapable. Hole is an area in sensor network around which sensors cease to sense or communicate due to drainage of battery or any fault, either temporary or permanent. Holes impair sensing and communication functions of network; thus their identification is a major concern. This paper discusses different types of holes and significance of hole detection in wireless sensor networks. Coverage hole detection schemes have been classified into three categories based on the type of information used by algorithms, computation model, and network dynamics for better understanding. Then, relative strengths and shortcomings of some of the existing coverage hole detection algorithms are discussed. The paper is concluded by highlighting various future research directions. Pearl Antil and Amita Malik Copyright © 2014 Pearl Antil and Amita Malik. All rights reserved. Bandwidth-Aware Scheduling of Workflow Application on Multiple Grid Sites Thu, 11 Sep 2014 00:00:00 +0000 Bandwidth-aware workflow scheduling is required to improve the performance of a workflow application in a multisite Grid environment, as the data movement cost between two low-bandwidth sites can adversely affect the makespan of the application. Pegasus WMS, an open-source and freely available WMS, cannot fully utilize its workflow mapping capability due to unavailability of integration of any bandwidth monitoring infrastructure in it. This paper develops the integration of Network Weather Service (NWS) in Pegasus WMS to enable the bandwidth-aware mapping of scientific workflows. Our work demonstrates the applicability of the integration of NWS by making existing Heft site-selector of Pegasus WMS bandwidth aware. Furthermore, this paper proposes and implements a new workflow scheduling algorithm—Level based Highest Input and Processing Weight First. The results of the performed experiments indicate that the bandwidth-aware workflow scheduling algorithms perform better than bandwidth-unaware algorithms: Random and Heft of Pegasus WMS. Moreover, our proposed workflow scheduling algorithm performs better than the bandwidth-aware Heft algorithms. Thus, the proposed bandwidth-aware workflow scheduling enhances capability of Pegasus WMS and can increase performance of workflow applications. Harshadkumar B. Prajapati and Vipul A. Shah Copyright © 2014 Harshadkumar B. Prajapati and Vipul A. Shah. All rights reserved. Cross-Layer Scheduling and Resource Allocation for Heterogeneous Traffic in 3G LTE Tue, 26 Aug 2014 05:32:47 +0000 3G long term evolution (LTE) introduces stringent needs in order to provide different kinds of traffic with Quality of Service (QoS) characteristics. The major problem with this nature of LTE is that it does not have any paradigm scheduling algorithm that will ideally control the assignment of resources which in turn will improve the user satisfaction. This has become an open subject and different scheduling algorithms have been proposed which are quite challenging and complex. To address this issue, in this paper, we investigate how our proposed algorithm improves the user satisfaction for heterogeneous traffic, that is, best-effort traffic such as file transfer protocol (FTP) and real-time traffic such as voice over internet protocol (VoIP). Our proposed algorithm is formulated using the cross-layer technique. The goal of our proposed algorithm is to maximize the expected total user satisfaction (total-utility) under different constraints. We compared our proposed algorithm with proportional fair (PF), exponential proportional fair (EXP-PF), and U-delay. Using simulations, our proposed algorithm improved the performance of real-time traffic based on throughput, VoIP delay, and VoIP packet loss ratio metrics while PF improved the performance of best-effort traffic based on FTP traffic received, FTP packet loss ratio, and FTP throughput metrics. Richard Musabe and Hadi Larijani Copyright © 2014 Richard Musabe and Hadi Larijani. All rights reserved. Analysis of MIMO Receiver Using Generalized Least Squares Method in Colored Environments Wed, 20 Aug 2014 07:28:55 +0000 The classical detection techniques for multiple-input multiple-output (MIMO) systems are usually designed with the assumption that the additive complex Gaussian noise is uncorrelated. However, for closely spaced antennas, the additive noise is correlated due to the mutual antenna coupling. This letter analyzes an improved zero-forcing (ZF) technique for MIMO channels in colored environments. The additive noise is assumed to be correlated and the Rayleigh MIMO channel is considered doubly correlated. The improved ZF detector, based on the generalized least squares estimator (GLS), takes into account the noise covariance matrix and provides an unbiased estimator of the transmitted symbol vectors. We introduce some novel bounds on the achievable sum rate, on the normalized mean square error at the receiver output, and on the outage probability. The derived expressions are compared to Monte Carlo simulations. Mohamed Lassaad Ammari and Paul Fortier Copyright © 2014 Mohamed Lassaad Ammari and Paul Fortier. All rights reserved. A Regulation-Based Security Evaluation Method for Data Link in Wireless Sensor Network Wed, 16 Jul 2014 00:00:00 +0000 This article presents a novel approach to the analysis of wireless sensor networks (WSN) security, based on the regulations intended for wireless communication devices. Starting from the analysis and classification of attacks, countermeasures, and available protocols, we present the current state on secure communication stacks for embedded systems. The regulation analysis is based on civil EN 50150 and MIL STD-188-220, both applicable to WSN communications. Afterwards, starting from a list of known WSN attacks, we use a correspondence table to match WSN attacks with countermeasures required by regulations. This approach allows us to produce a precise security evaluation and classification methodology for WSN protocols. The results show that current protocols do not present a complete coverage of security issues. While this conclusion is already known for many WSN protocols, to the best of our knowledge this is the first time a complete methodology is proposed to base this assertion. Moreover, by using the proposed methodology, we are able to precisely identify the exposed threats for each WSN protocol under analysis. Claudio S. Malavenda, F. Menichelli, and M. Olivieri Copyright © 2014 Claudio S. Malavenda et al. All rights reserved. Performance Evaluation of MBA-OLSR Routing Protocol for MANETs Tue, 15 Jul 2014 13:15:52 +0000 This paper proposes a multipath battery aware routing protocol, namely, MBA-OLSR, based on OLSRv2 and its multipath extension. The proposed approach considers the remaining battery energy of the nodes for calculating the initial cost of the multiple links between source-destination pairs. The MBA-OLSR aims to construct energy efficient routes and extend the network lifetime to avoid network failure due to battery exhaustion. The protocol performance is evaluated in different simulation scenarios of wireless mobile ad hoc networks (MANETs) environment. The simulation results demonstrate that our approach can achieve longer network lifetime and lower energy cost per packet. In addition, the results show improvement in terms of packet delivery ratio and end-to-end delay. Waheb A. Jabbar, Mahamod Ismail, and Rosdiadee Nordin Copyright © 2014 Waheb A. Jabbar et al. All rights reserved. A New Wireless VoIP Signaling Device Supporting SIP and H.323 Protocols Wed, 02 Jul 2014 06:13:28 +0000 Nowadays, VoIP is a technology with a great demand and wireless networks are increasingly deployed. Each of these has its own technology constraints. For VoIP, it is very important to take into consideration the need to provide a high quality service according to well-defined standard transmission (jitter, end-to-end delay, MOS, and packet loss). However, wireless networks (IEEE 802.11) are based on radio which undergoes a number of technical constraints to achieve theoretical transmission rates; among these constraints the number of users of the networks, the distance between the client and the access, and the amount of data transmitted point are included. In this term, a study is made by simulating wireless network in OPNET Modeler with a fairly large number of VoIPs (15 users) whose signaling is handled via a new node that was created specifically to manage the signaling tasks under SIP and H.323 in order to minimize the number of nodes in the network and avoid the congestion. In this paper, two scenarios are compared; the first contains a number of VoIP users with SIP and H.323 signaling handled by the new created device; the second scenario is similar to the first except that the distance between the stations is remarkably lower. Salma Rattal, Abdelmajid Badri, and Mohammed Moughit Copyright © 2014 Salma Rattal et al. All rights reserved. Survivable Network Design and Optimization with Network Families Tue, 01 Jul 2014 09:34:42 +0000 In modeling communication networks for simulation of survivability schemes, one goal is often to implement these schemes across varying degrees of nodal connectivity to get unbiased performance results. Abstractions of real networks, simple random networks, and families of networks are the most common categories of these sample networks. This paper looks at how using the network family concept provides a solid unbiased foundation to compare different network protection models. The network family provides an advantage over random networks by requiring one solution per average nodal degree, as opposed to having to solve many, which could take a significant amount of time. Also, because the network family looks at a protection scheme across a variety of average nodal connectivities, a clearer picture of the scheme’s performance is gained compared to just running the simulation on a single network or select few networks. Brody Todd, Abiose Ibigbami, and John Doucette Copyright © 2014 Brody Todd et al. All rights reserved. Wavelength Tuning Free Transceiver Module in OLT Downstream Multicasting    Gb/s TWDM-PON System Thu, 26 Jun 2014 06:02:02 +0000 We propose a new architecture of dynamic time-wavelength division multiplexing-passive optical network (TWDM-PON) system that employs integrated all-optical packet routing (AOPR) module using  Gbps downstream signal to support 20 km fiber transmission. This module has been designed to support high speed L2 aggregation and routing in the physical layer PON system by using multicasting cross-gain modulation (XGM) to route packet from any PON port to multiple PON links. Meanwhile, the fixed wavelength optical line terminal (OLT) transmitter with wavelength tuning free features has been designed to integrate with the semiconductor optical amplifier (SOA) and passive arrayed waveguide grating (AWG). By implementing hybrid multicasting and multiplexing, the system has been able to support a PON system with full flexibility function for managing highly efficient dynamic bandwidth allocation to support the  Gb/s TWDM-PON system used to connect 4 different PON links using fixed wavelength OLT transceivers with maximum 38 dB link loss. M. S. Salleh, A. S. M. Supa’at, S. M. Idrus, S. Yaakob, and Z. M. Yusof Copyright © 2014 M. S. Salleh et al. All rights reserved. SCAR: A Coding-Aware Routing Protocol with Self-Recommendation in Static Wireless Ad Hoc Networks Wed, 25 Jun 2014 10:56:21 +0000 There have been researchers working on the design of coding-aware routing protocols to exploit the power of network coding in static wireless ad hoc networks. However, most of them have overlooked the fact that routing decisions for multiple flows need to be coordinated in order to achieve maximum throughput. A mechanism to alter prior routing decisions is mandatory for this purpose. In this paper, we propose Self-recommendation coding-aware routing (SCAR), to provide such a mechanism. With intermediate nodes sensing the arrival of new flows, they can send self-recommendations to source nodes, triggering a route-change procedure. In the route-change procedure, adjustments are applied to the route metrics so that the newly recommended route can be fairly weighed without bias. A thorough analysis of coding structures is carried out, and a series of indicators are devised to predict how much throughput benefits we can gain from the mere knowledge of the topology. The rationale behind the protocol design and the effectiveness of the indicators are further justified by a series of simulations. Results show that SCAR can exploit coding opportunities better and provide higher throughput than other coding-aware routing protocols. It is also shown that the opportunity of throughput gain is ubiquitous and it is tested on many typical topologies. Jin Wang, Cenzhe Zhu, Teck Yoong Chai, and Wai-Choong Wong Copyright © 2014 Jin Wang et al. All rights reserved. Impact of Feedback Channel Delay over Joint User Scheduling Scheme and Separated Random User Scheduling Scheme in LTE-A System with Carrier Aggregation Thu, 12 Jun 2014 08:37:02 +0000 In Long Term Evolution-Advanced (LTE-A), the signal quality in a wireless channel is estimated based on the channel quality measurements. The measurement results are used to select suitable modulation and coding scheme for each transmission, feedback, and processing delay, which can cause a mismatch between channel quality information (CQI) and current channel state at the base station. However, prospect delays in the reception of such CQI may lead to a system performance degradation. This study analyzes the impact of CQI feedback delay on joint user scheduling (JUS) scheme and separated random user scheduling (SRUS) scheme in LTE-A system over carrier aggregation. The analysis will be compared with the system having delayed channel and perfect knowledge at different deployment scenario. We will study the throughput performance of both scheduling schemes with different deployment scenario, and then recommend the suitable deployment scenario to keep the desired QoS for a specific number of users. Results show that, in main beam directed at sector boundaries and diverse coverage, JUS scheme performs better than SRUS, which can justify the intensive use of user equipment power and extra control signaling overhead. Ahmed A. Ali, Rosdiadee Nordin, Mahamod Ismail, and Huda Abdullah Copyright © 2014 Ahmed A. Ali et al. All rights reserved. On the Performance of the Current MANET Routing Protocols for VoIP, HTTP, and FTP Applications Mon, 17 Feb 2014 11:51:53 +0000 The recent advances of ensemble mobile environment of smart devices with embedded sensors have enabled the MANET to play a key role in the smart cities as well as WSN and WMN. However, these smart devices are still limited in terms of energy, processor, and memory. Moreover, the efficient routing for reliable network connectivity at anytime, anywhere, and about everything is still a challenge in multihop wireless networks. This paper evaluates the QoS and energy efficiency of three active routing protocols: (i) OLSRv2, a successor to OLSR, (ii) DYMO, a successor to both DSR and AODV, and (iii) MP-OLSR multipath extension to OLSRv2. In contrast to the related previous works which focused only on CBR traffic without considering the influence of specific traffic types on the performance of routing protocols, this work focused on this area from a different perspective. It evaluates the performance of three internet-based traffic types that can be used in the smart city applications: VoIP, HTTP, and FTP using different simulation models. The impact of the network density, load traffic, and nodes mobility on the considered protocols was evaluated by considering particular performance metrics for each traffic application. Based on the results, the study concludes by presenting useful recommendations for future work. Waheb A. Jabbar, Mahamod Ismail, and Rosdiadee Nordin Copyright © 2014 Waheb A. Jabbar et al. All rights reserved. Exploratory Analysis of a GGSN’s PDP Context Signaling Load Thu, 13 Feb 2014 14:05:13 +0000 This paper takes an exploratory look on control plane signaling in a mobile cellular core network. In contrast to most contributions in this field, our focus does not lie on the wireless or user-oriented parts of the network, but on signaling in the core network. In an investigation of core network data we take a look at statistics related to GTP tunnels and their signaling. Based on the results thereof we propose a definition of load at the GGSN and create an initial load queuing model. We find signs of user devices putting burden on the core network through their behavior. Florian Metzger, Albert Rafetseder, Peter Romirer-Maierhofer, and Kurt Tutschku Copyright © 2014 Florian Metzger et al. All rights reserved. Impact of Loss Synchronization on Reliable High Speed Networks: A Model Based Simulation Sun, 19 Jan 2014 14:05:19 +0000 Contemporary nature of network evolution demands for simulation models which are flexible, scalable, and easily implementable. In this paper, we propose a fluid based model for performance analysis of reliable high speed networks. In particular, this paper aims to study the dynamic relationship between congestion control algorithms and queue management schemes, in order to develop a better understanding of the causal linkages between the two. We propose a loss synchronization module which is user configurable. We validate our model through simulations under controlled settings. Also, we present a performance analysis to provide insights into two important issues concerning 10 Gbps high speed networks: (i) impact of bottleneck buffer size on the performance of 10 Gbps high speed network and (ii) impact of level of loss synchronization on link utilization-fairness tradeoffs. The practical impact of the proposed work is to provide design guidelines along with a powerful simulation tool to protocol designers and network developers. Suman Kumar, Lin Xue, and Seung-Jong Park Copyright © 2014 Suman Kumar et al. All rights reserved. Efficient Cluster Head Selection Algorithm for MANET Tue, 24 Dec 2013 19:26:32 +0000 In mobile ad hoc network (MANET) cluster head selection is considered a gigantic challenge. In wireless sensor network LEACH protocol can be used to select cluster head on the bases of energy, but it is still a dispute in mobil ad hoc networks and especially when nodes are itinerant. In this paper we proposed an efficient cluster head selection algorithm (ECHSA), for selection of the cluster head efficiently in Mobile ad hoc networks. We evaluate our proposed algorithm through simulation in OMNet++ as well as on test bed; we experience the result according to our assumption. For further evaluation we also compare our proposed protocol with several other protocols like LEACH-C and consequences show perfection. Khalid Hussain, Abdul Hanan Abdullah, Saleem Iqbal, Khalid M. Awan, and Faraz Ahsan Copyright © 2013 Khalid Hussain et al. All rights reserved. Survey of Green Radio Communications Networks: Techniques and Recent Advances Sun, 22 Dec 2013 11:03:50 +0000 Energy efficiency in cellular networks has received significant attention from both academia and industry because of the importance of reducing the operational expenditures and maintaining the profitability of cellular networks, in addition to making these networks “greener.” Because the base station is the primary energy consumer in the network, efforts have been made to study base station energy consumption and to find ways to improve energy efficiency. In this paper, we present a brief review of the techniques that have been used recently to improve energy efficiency, such as energy-efficient power amplifier techniques, time-domain techniques, cell switching, management of the physical layer through multiple-input multiple-output (MIMO) management, heterogeneous network architectures based on Micro-Pico-Femtocells, cell zooming, and relay techniques. In addition, this paper discusses the advantages and disadvantages of each technique to contribute to a better understanding of each of the techniques and thereby offer clear insights to researchers about how to choose the best ways to reduce energy consumption in future green radio networks. Mohammed H. Alsharif, Rosdiadee Nordin, and Mahamod Ismail Copyright © 2013 Mohammed H. Alsharif et al. All rights reserved. Analytical Performance Evaluation of Different Switch Solutions Thu, 12 Dec 2013 14:04:33 +0000 The virtualization of the network access layer has opened new doors in how we perceive networks. With this virtualization of the network, it is possible to transform a regular PC with several network interface cards into a switch. PC-based switches are becoming an alternative to off-the-shelf switches, since they are cheaper. For this reason, it is important to evaluate the performance of PC-based switches. In this paper, we present a performance evaluation of two PC-based switches, using Open vSwitch and LiSA, and compare their performance with an off-the-shelf Cisco switch. The RTT, throughput, and fairness for UDP are measured for both Ethernet and Fast Ethernet technologies. From this research, we can conclude that the Cisco switch presents the best performance, and both PC-based switches have similar performance. Between Open vSwitch and LiSA, Open vSwitch represents a better choice since it has more features and is currently actively developed. Francisco Sans and Eric Gamess Copyright © 2013 Francisco Sans and Eric Gamess. All rights reserved.