Current Issue : January - March Volume : 2015 Issue Number : 1 Articles : 5 Articles
Nowadays, mobile ad hoc networks (MANETs) have to support new applications including VoIP (voice over IP) that impose\nstringent QoS (quality of service) constraints and requirements. However, VoIP applications make a very inefficient use of the\nMANET resources. Our work represents a first step toward improving aspects at the network layer by addressing issues from the\nstandpoint of adaptation, claiming that effective adaptation of routing parameters can enhance VoIP quality.The most important\ncontribution is the adaptive OLSR-VA algorithm which provides an integrated environment where VoIP activity is constantly\ndetected and routing parameters are adapted in order to meet the application requirements. To investigate the performance\nadvantage achieved by such algorithm, a number of realistic simulations (MANET scenarios) are performed under different\nconditions. The most important observation is that performance is satisfactory in terms of the perceived voice quality....
This article presents a novel approach to the analysis of wireless sensor networks (WSN) security, based on the regulations\nintended forwireless communication devices. Starting fromthe analysis and classification of attacks, countermeasures, and available\nprotocols, we present the current state on secure communication stacks for embedded systems. The regulation analysis is based on\ncivil EN 50150 and MIL STD-188-220, both applicable to WSN communications. Afterwards, starting from a list of known WSN\nattacks,we use a correspondence table tomatchWSNattacks with countermeasures required by regulations. This approach allows us\nto produce a precise security evaluation and classification methodology forWSN protocols. The results show that current protocols\ndo not present a complete coverage of security issues.While this conclusion is already known for manyWSN protocols, to the best\nof our knowledge this is the first time a complete methodology is proposed to base this assertion.Moreover, by using the proposed\nmethodology, we are able to precisely identify the exposed threats for eachWSN protocol under analysis...
The classical detection techniques for multiple-input multiple-output (MIMO) systems are usually designed with the assumption\nthat the additive complex Gaussian noise is uncorrelated. However, for closely spaced antennas, the additive noise is correlated\ndue to the mutual antenna coupling. This letter analyzes an improved zero-forcing (ZF) technique for MIMO channels in colored\nenvironments. The additive noise is assumed to be correlated and the Rayleigh MIMO channel is considered doubly correlated. The\nimproved ZF detector, based on the generalized least squares estimator (GLS), takes into account the noise covariance matrix and\nprovides an unbiased estimator of the transmitted symbol vectors. We introduce some novel bounds on the achievable sum rate,\non the normalized mean square error at the receiver output, and on the outage probability.The derived expressions are compared\nto Monte Carlo simulations....
3G long term evolution (LTE) introduces stringent needs in order to provide different kinds of traffic with Quality of Service (QoS)\ncharacteristics. The major problem with this nature of LTE is that it does not have any paradigm scheduling algorithm that will\nideally control the assignment of resources which in turn will improve the user satisfaction. This has become an open subject and\ndifferent scheduling algorithms have been proposed which are quite challenging and complex. To address this issue, in this paper,\nwe investigate how our proposed algorithm improves the user satisfaction for heterogeneous traffic, that is, best-effort traffic such as\nfile transfer protocol (FTP) and real-time traffic such as voice over internet protocol (VoIP). Our proposed algorithm is formulated\nusing the cross-layer technique. The goal of our proposed algorithm is to maximize the expected total user satisfaction (totalutility)\nunder different constraints. We compared our proposed algorithm with proportional fair (PF), exponential proportional\nfair (EXP-PF), and U-delay. Using simulations, our proposed algorithm improved the performance of real-time traffic based on\nthroughput, VoIP delay, and VoIP packet loss ratio metrics while PF improved the performance of best-effort traffic based on FTP\ntraffic received, FTP packet loss ratio, and FTP throughput metrics....
This paper proposes amulti path battery aware routing protocol, namely,MBA-OLSR, based onOLSRv2 and its multi path extension.\nThe proposed approach considers the remaining battery energy of the nodes for calculating the initial cost of the multiple links\nbetween source-destination pairs. The MBA-OLSR aims to construct energy efficient routes and extend the network lifetime to\navoid network failure due to battery exhaustion. The protocol performance is evaluated in different simulation scenarios of wireless\nmobile ad hoc networks(MANETs) environment. The simulation results demonstrate that our approach can achieve longer network\nlifetime and lower energy cost per packet. In addition, the results show improvement in terms of packet delivery ratio and end-toend\ndelay....
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