Research And Improvement On MAC Protocol In Wireless Mesh Networks

Based on the performance analysis of MAC protocol for WMN (Wireless Mesh Networks), an improved MAC protocol is researched in this thesis.Firstly, the present research status, application domain, system structure and main feature of WMN are introduced briefly in this thesis. Secondly, the IEEE802.11 MAC protocol used in WMN is introduced, with emphasis on the performance of IEEE802.11 DCF protocol. The analysis result shows that the system throughput is closely related with the network size (the number of competing nodes in the network).Thirdly, a self-adaptive algorithm S-DCF is researched for estimating the present number of competing nodes in the network. The main idea of S-DCF is to count the number of different source MAC addresses contained in the header of successfully transmitted MAC frames. Simulation result shows that as the life time of MAC address being set appropriately, S-DCF algorithm can accurately estimate the number of competing nodes in the different networks.Lastly, Based on S-DCF, an improved MAC protocol optimal-DCF is researched with its main idea of adjusting the minimum contention window according to the estimated number. Simulation result in a multi-hop network by using the OPNET shows that the performance of optimal-DCF is much better than IEEE802.11DCF.