Prioritization scheme for QoS in IEEE 802.11e WLAN

The exponential growth in demand for multimedia applications in wireless network has resulted in dramatic increased in different devices and connections accessing information.Indeed, this is primarily due to the fact that wireless and multimedia applications have been used quite extensively in business, commercial and communication industry.Supporting multimedia application in wireless environment with different bandwidth and delay requirement is challenging – this can eventually have detrimental impact on the system performance if the necessary quality of service (QoS) requirement has not been provided.This paper presents an approach which prioritizes the application base on its content in order to ultimately support and provide the needed requirements for multimedia application over wireless LAN.Consequently, the throughput of the IEEE 802.11e while maintaining its QoS requirement.The scheme has been simulated using NS2 simulator

Frame-based mapping mechanism for energy-efficient MPEG-4 video transmission over IEEE 802.11e networks with better quality of delivery

Recent developments in hardware, software and communication technologies have resulted in increasing interest in the use of wireless local area networks (WLANs). Mobile devices with embedded WLAN functionality are becoming increasingly popular. Such devices must be designed to support applications that require high quality of service (QoS) and have favorable to maximize battery capacity. The resources of queues in IEEE 802.11e networks may be wasted by the transmission of information that is useless to the receiver. This work develops a frame-based mapping mechanism (FBM) that exploits different methods to process I/P/B (Intra/Predictive/Bipredictive) video frame packets. FBM refers to the dropping of arriving packets if the preceding packets in the same video frame have been dropped. When fragmented packets of a single frame are allocated to different access categories (AC) queues, out-of order delivery may occur. Hence, FBM tries to treat all fragmented packets of each video frame equally and allocates them to the same AC queue if possible. The simulation results demonstrate that transmission by the FBM is more efficient than that by other mechanisms, such as EDCA (Enhanced Distributed Channel Access), static mapping and adaptive mapping, suggesting that the energy of a device is not wasted in the transmission of useless video data in WLANs. (C) 2015 Elsevier Ltd. All rights reserved.Foundation item: The National Project of Taiwan (No.: MOST 103-2221-E507-001). Authors are grateful to Ministry of Science and Technology Grant no. (MOST 103-2221-E507-001), Government of Taiwan for financial support to carry out this work.Ke, C.; Yang, C.; Chen, J.; Ghafoor, KZ.; Lloret, J. (2015). Frame-based mapping mechanism for energy-efficient MPEG-4 video transmission over IEEE 802.11e networks with better quality of delivery. Journal of Network and Computer Applications. 58:280-286. https://doi.org/10.1016/j.jnca.2015.08.005S2802865

Joint in-network video rate adaptation and measurement-based admission control: algorithm design and evaluation

The important new revenue opportunities that multimedia services offer to network and service providers come with important management challenges. For providers, it is important to control the video quality that is offered and perceived by the user, typically known as the quality of experience (QoE). Both admission control and scalable video coding techniques can control the QoE by blocking connections or adapting the video rate but influence each other's performance. In this article, we propose an in-network video rate adaptation mechanism that enables a provider to define a policy on how the video rate adaptation should be performed to maximize the provider's objective (e.g., a maximization of revenue or QoE). We discuss the need for a close interaction of the video rate adaptation algorithm with a measurement based admission control system, allowing to effectively orchestrate both algorithms and timely switch from video rate adaptation to the blocking of connections. We propose two different rate adaptation decision algorithms that calculate which videos need to be adapted: an optimal one in terms of the provider's policy and a heuristic based on the utility of each connection. Through an extensive performance evaluation, we show the impact of both algorithms on the rate adaptation, network utilisation and the stability of the video rate adaptation. We show that both algorithms outperform other configurations with at least 10 %. Moreover, we show that the proposed heuristic is about 500 times faster than the optimal algorithm and experiences only a performance drop of approximately 2 %, given the investigated video delivery scenario

PERFORMANCE EVALUATION OF CROSS-LAYER DESIGN WITH DISTRIBUTED AND SEQUENTIAL MAPPING SCHEME FOR VIDEO APPLICATION OVER IEEE 802.11E

The rapid development of wireless communication imposes several challenges to support QoS for real-time multimedia applications such as video stream applications. Researchers tackled these challenges from different points of view including the semantics of the video to achieve better QoS requirements. The main goal of this research is to design a UDP protocol to realize a distributed sequential mapping scheme (DSM) with a cross-layer design and evaluate its accuracy under different network conditions. In DSM, the perceived quality of a multi-layer video is addressed by mapping each video layer into channel resources represented as queues or access categories (ACs) existing in IEEE 802.11e MAC layer. This research work further investigates the efficiency of this scheme with actual implementation and thorough simulation experiments. The experiments reported the efficiency of this scheme with the presence of different composite traffic models covering most known traffic scenarios using Expected Reconstructed Video Layers (ERVL) and packet loss rate as accuracy measures. This research work also investigates the accuracy of calculating the ERVL compared to its value using actual readings of layers drop rate. The effect of changing the ACs queue size on the ERVL is studied. The use of this scheme shows zero-drop in the base layer in almost all scenarios where no ongoing traffic is presented except that the testing video sessions between nodes. In these experiments, the ERVL continuously reported high values for the number of expected reconstructed video layers. While these values dramatically vary when introducing ongoing different composite traffic models together with the testing video sessions between nodes. Finally, a 40% increase in the ACs queue size shows significant improvement on ERVL while an increase of the queue size beyond this value has very little significance on ERVL

A Markov Chain Approach to IEEE 802.11WLAN Performance Analysis

Wireless communication always attracts extensive research interest, as it is a core part of modern communication technology. During my PhD study, I have focused on two research areas of wireless communication: IEEE 802.11 network performance analysis, and wireless cooperative retransmission. The first part of this thesis focuses on IEEE 802.11 network performance analysis. Since IEEE 802.11 technology is the most popular wireless access technology, IEEE 802.11 network performance analysis is always an important research area. In this area, my work includes the development of three analytical models for various aspects of IEEE 802.11 network performance analysis. First, a two-dimensional Markov chain model is proposed for analysing the performance of IEEE 802.11e EDCA (Enhanced Distributed Channel Access). With this analytical model, the saturated throughput is obtained. Compared with the existing analytical models of EDCA, the proposed model includes more correct details of EDCA, and accordingly its results are more accurate. This better accuracy is also proved by the simulation study. Second, another two-dimensional Markov chain model is proposed for analysing the coexistence performance of IEEE 802.11 DCF (Distributed Coordination Function) and IEEE 802.11e EDCA wireless devices. The saturated throughput is obtained with the proposed analytical model. The simulation study verifies the proposed analytical model, and it shows that the channel access priority of DCF is similar to that of the best effort access category in EDCA in the coexistence environment. The final work in this area is a hierarchical Markov chain model for investigating the impact of data-rate switching on the performance of IEEE 802.11 DCF. With this analytical model，the saturated throughput can be obtained. The simulation study verifies the accuracy of the model and shows the impact of the data-rate switching under different network conditions. A series of threshold values for the channel condition as well as the number of stations are obtained to decide whether the data-rate switching should be active or not. The second part of this thesis focuses on wireless cooperative retransmission. In this thesis, two uncoordinated distributed wireless cooperative retransmission strategies for single-hop connection are presented. In the proposed strategies, each uncoordinated cooperative neighbour randomly decide whether it should transmit to help the frame delivery depending on some pre-calculated optimal transmission probabilities. In Strategy 1, the source only transmits once in the first slot, and only the neighbours are involved in the retransmission attempts in the subsequent slots. In Strategy 2, both the source and the neighbours participate in the retransmission attempts. Both strategies are first analysed with a simple memoryless channel model, and the results show the superior performance of Strategy 2. With the elementary results for the memoryless channel model, a more realistic two-state Markov fading channel model is used to investigate the performance of Strategy 2. The simulation study verifies the accuracy of our analysis and indicates the superior performance of Strategy 2 compared with the simple retransmission strategy and the traditional two-hop strategy