Volume 14, Issue 2, June 2012

Optimizing Service Differentiation Scheme with Sized-based Queue Management in DiffServ Networks [Full Text]

Nadim K. M. Madi and Mohamed Othman

Abstract— In this paper we introduced Modified Sized-based Queue Management as a dropping scheme that aims to fairly prioritize and allocate more service to VoIP traffic over bulk data like FTP as the former one usually has small packet size with less impact to the network congestion. In the same time, we want to guarantee that this prioritization is fair enough for both traffic types. On the other hand we study the total link delay over the congestive link with the attempt to alleviate this congestion as much as possible at the by function of early congestion notification. Our M-SQM scheme has been evaluated with NS2 experiments to measure the packets received from both and total link-delay for different traffic. The performance evaluation results of M-SQM have been validated and graphically compared with the performance of other three legacy AQMs (RED, RIO, and PI). It is depicted that our M-SQM outperformed these AQMs in providing QoS level of service differentiation. 

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Deploying and Configuring Wireless Mesh Network in Coexistence of Highly Interfering Wireless LANs [Full Text]

Lamia Romdhani and Amr Mohamed

Abstract— In wireless mesh network, environmental conditions and location of “nodes” on the network are largely unpredictable and in a constant state of change. Heterogeneous signal propagation patterns in addition to interference from existing infrastructure pose significant challenges for a wireless mesh network design. In this paper, we explore, by experiments, link performance results produced at Qatar University (QU) wireless mesh test-bed in the coexistence of high interfering wireless transmission. We first perform signal strength measurements for path loss, shadowing, and fading at 2.4/5 GHz frequencies. Then, we investigate the effect of unique cell structure, and heavy lab machinery of the engineering building on the link performance. Furthermore, we study different wireless mesh node configurations and equipments’ effect on performance and network connectivity. The causes behind link instability and performance shortcoming of the QU wireless mesh network (QUMESH) are identified. Our analysis reveals that the link performance degradation is caused by high interference with wireless LANs, and special QU College of engineering structure. Our work provides insights to network designers to realize high-performance wireless networks by considering the adequate configuration, equipments, and addressing the adaptive transmission approaches. 

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An Adaptive Duty Cycle based QOS-MAC Protocol for WSN [Full Text]

Smita Pawar and Prabha kasliwal

Abstract—  A wireless sensor network (WSN) is a group of sensors that are geographically distributed and interconnected by wireless networks. WSNs are growing at a tremendous pace, just like the exploding evolution of Internet. Supporting quality of service (QoS) will be of critical importance for pervasive WSNs that serve as the network infrastructure of diverse applications. In this paper, we assess the state of the art of Quality of Services (QoS) support in wireless sensor networks (WSNs) and employ various methods to improve performance factors like throughput,end to end delay,Packet delivery ratio etc.In this paper we have proposed a medium access control (MAC) protocol for providing quality of service (QoS) in wireless sensor networks (WSNs) which provides traffic based dynamic adjustment of the duty cycle of the nodes . The proposed MAC utilizes the advantages of carrier- sense multiple access (CSMA) and is an energy-efficient, priority-based, and QoS compatible MAC protocol. Performance evaluation is conducted between S-MAC and T-MAC with respect to three performance metrics: throughput, End to End delay and PDR (packet delivery ratio). The simulation results on NS2 simulator show that the performance of proposed-MAC is better than that of S-MAC and T-MAC. 

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Digital Video Compression using Embedded Zero tree Wavelet Encoding and Non uniform Quantization [Full Text]

Samir J.AL-Muraab

Abstract- Video Compression is a process of reducing the file size without degrading the video quality. This is achieved by reducing the redundancy between consecutive frames and within a single frame. Motion estimation is used to reduce temporal redundancy between frames by dividing the frame in to blocks and search for the best match according to the cost function. The proposed compression system uses the conventional red , green and blue color space representation and applies a two dimension discrete wavelet transform on the error residual signal before estimating the motion between frames. A value of threshold is assigned to the subband coefficients; a second of threshold is assigned to the second level detail subband coefficients. The second value is less than the first value . The resulting coefficients are quantized using a non-uniform quantizer and encoded using the EZW encoding algorithm. The system will be tested using two kinds of videos (simple, complex). The performance of the system will be tested by three main parameters; compression ratio(CR), Peak signal to noise ratio(PSNR) and processing time(PT). All graphics and codes are executed using MATLAB2008a. 

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Design of Multiband Ultra-Wideband (UWB) System Based on Discrete Multi wavelets Transform  [Full Text]

Laith Ali Abdul-Rahaim and Samir Jasam Mohammad

Abstract - In this paper design and performances are investigated for Multiband ultra-wideband systems MB-UWB Based on Discrete Multiwavelets Transform Critically Sampling DMWTCS. The design of MB-UWB systems, with the goal of achieving 528Mbps data rate is present. The performances of these systems with different channel models schemes are simulated. The Bit Error Rate (BERs) and the operating range of these systems are obtained using frequency domain baseband simulations as well as more realistic full-system simulations, and are compared to other systems types designed using FFT and Discrete Wavelets transform DWT. Simulation results show that the MB-UWB system using DMWTCS provide significant gains for 528 Mbps transmission over MB- UWB systems using conventional method with FFT and DWT. Performance simulations validate the concept of the multicarrier Multiband Direct sequence ultra-wideband systems and demonstrate the promising features of the DMWTCS. However, a critical comparison to a conventional method scheme indicates that the final gain may not justify the extra complexity. The simulations are achieved by MATLAB R2010a.

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Pairwise Key Establishment Technique Based Message Authentication For Wireless sensor Network [Full Text]

Mr. Manishkumar H. Patel and Prof. Dipti Sakhare

Abstract—Sensor networks are vulnerable to false data injection attack and path-based denial of service (PDoS) attack. In these attacks the intruder tries to exhaust the resources available to the victim node, by sending extra unnecessary packets and thus prevents legitimate network users from accessing services or resources to which they are entitled. Numerous authentication schemes have been proposed in the past for protecting authenticity and integrity in wireless sensor network.To address these issues,we present a Constrained Function based en- route Filtering (CFA) scheme for message Authentication in wireless sensor networks in which each node have an en-route filtering capabil- ity.The authentication scheme which is mainly constructed from the carpy+ scheme.carpy+ scheme is nothing but the noninteractive pair- wisekey establishment technique.For this CFA based authentication scheme we are mainly going to implement Off line and On line step of CFA scheme and we observe the various parameter related to to WSN for eg. energy consumption,packet delivery ratio etc.