Improvements Of MAC Access Scheme And Routing Protocol In IEEE 802.11s Wireless Mesh Networks

Because of its low cost and easy distribution, Wireless Mesh Network is widely used in the market. As the standards relating WMN are inmature, lots of study is being done by the worldwide scholars. In this paper, the MAC access scheme and routing protocol in IEEE 802.11s draft is improved.In the IEEE 802.11s draft, the Enhanced Distributed Channel Access (EDCA) of 802.11e is totally adopted as the MAC scheme of Wireless Mesh Network (WMN). Regardless of the network’s condition, the value of every data traffic’s Contention Window (CW) and the policy of resetting CW is fixed. So the EDCA is not completely suitable for WMN which has numerous nodes, flexible topology and complex environment. In some study, EDCA of 802.11e was improved and an Adaptive EDCA (AEDCA) was proposed to make the CW change according to the collision probability in the network. In this paper, a New Adaptive EDCA (N-AEDCA) based on AEDCA was proposed, which is more suitable for the 802.11s wireless mesh network. In N-AEDCA, the Frame Error Rate (FER) and the average collision probability are introduced, so that CW can be changed more slowly according to the network’s condition and different data categories. The simulation results show that it helps to ensure the Quality of Service (QoS), reduce the packets loss rates and increase the total throughput of the network.To improve the ability of Qos ensurence, a Service-Based Routing Protocol is proposed here. It is based on the frame of Optimized Link State Routing Protocol and message of data type, routing cost, available bandwidth in MAC are introduced to measure the routing.