MAC Protocol Research For Wireless Mesh Network Based On IEEE802.11

Wireless Mesh Network (WMN), a static multi-hop wireless network connecting routers and terminal devices with wireless links, is a type of broadband wireless access systems. WMN is a combination of WLAN and mobile Ad hoc network with the characteristics of reliability, self-organization and self-healing. At present, WMN is gaining more and more significant attention around the world. Since channel allocation and management is a key factor influencing networks performance optimization, MAC protocols for WMN have become hot research topics. After introducing architectures, characteristics and key technologies of WMN, as well as the existing single channel and multi-channel MAC protocols, this thesis focuses on IEEE802.11 DCF (Distributed Coordination Function) as its research basis and starting point, which is one of the most popular MAC protocols in present mobile network applications.Based on IEEE802.11DCF, a Medium Access Control (MAC) protocol is proposed for wireless mesh network. It is consisted of two key mechanisms: dynamic-delay backoff algorithm and congestion control mechanism. The main idea of the proposed protocol is to arrange dynamic delay backoff for each node according to real contention status around it, and provide network congestion control. Simulation is operated with OPNET, and the simulation results show that the proposed scheme can improve the fairness of channel access, and effectively reduce the average end-to-end delay, mitigate packet dropped ratio, as well as provide simple QoS support.