Study Of MAC And Resource Management In Wireless Broadband Networks

Recent advances in portable computing and wireless technologies are opening up exciting possibilities for the future of wireless networks. There are great differences between wireline network and wireless network. The channel is shared by all nodes in the wireless networks. PHY layer provides the wireless channel and MAC layer manages the transmission of information over the channel. With the richness of traffic types and the increase of bandwidth, MAC will play a more and more important role in the performance of wireless network. More notably, Wireless Local and Metropolitan Area Networks (WLAN and WMAN) technologies are expected to revolutionize the way we live. Given their unprecedented importance, in the dissertation we investigate the performance of MAC layer and suggest some new solutions in the context of WLAN and WMAN, including Ad hoc network. The main contributions are as follows:(1) By the analysis of the Enhanced Distributed Channel Access (EDCA) of IEEE 802.11e wireless LANs, a four-dimension Markov chain model is proposed in this paper. Based on the Markov model, We have studied the priority differentiation based on backoff and based on Inter-Frame Space (IFS). The research takes the real collision and virtual collision into account. The consistency of analysis and simulation validates the Markov chain model. By analyzing the simulation results, we find some performance deficiencies of IEEE 802.11 e EDCA.(2) We introduce an enhanced QoS mechanism for IEEE 802.11e EDCA based on the previous conclusion. There are three parts in this QoS architecture: Firstly, the collision separation among many ACes is implemented through the virtual queuing in QAP. Secondly, to guarantee the previous traffic, it is necessary to control the access of these ACes with the same priority. Finally, the saturated throughput of the ACfO] achieves the stable maximum by adjusting the initial contention window. Because of the equal transmitting opportunity, it is fair among BE traffics. The analysis and simulation validate the efficiency of our algorithm.(3) Based on the analysis of some performance factors of Mobile Ad hoc NETwork (MANET), a clustering algorithm is proposed to improve the scalability of Ad hoc network. By considering the node mobility and node locality in the network, this clustering algorithm is aimed at a more stable clustering structure. We model the relative mobility between a node and its neighbor nodes by the concept of Entropy in information theory. And we estimate the contribution of a node to the whole network by the concept of the Node Degree in graph theory. Based on the Entropy and Node Degree,...