Study on IEEE 802.11s MDA Reservation Mechanism for Multi-channel Wireless Mesh Network

• Main Authors: Hung-chun Chen, 陳鴻鈞
• Other Authors: Bih-Hwang Lee
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/04687727727333745795

碩士 === 國立臺灣科技大學 === 電機工程系 === 98 === A wireless mesh LAN is a communications network made up of radio nodes that support mesh service. It combines the feature of ad hoc network, so nodes can communicate with other nodes directly without access point (AP). According to this feature, we can deploy network with larger coverage and lower cost. Because all based on carrier sense multiple access with collision avoidance (CSMA/CA) base to IEEE 802.11 a/b/g wireless system at present, the collision probability will be much higher if we use the scheme in wireless mesh LAN. In IEEE 802.11s draft, not only the mesh network topology be introduced, but also a new reservation based MAC access scheme, MDA, be introduced. Nodes that support MDA can access wireless medium with lower collision probability, but it can just work in single channel, so the capacity of network is limited. In order to solve the above-mentioned problem, we proposed a new multi-channel access scheme that improved from MDA. We divide the mesh DTIM (delivery traffic indication map) interval into two fields, contention field and transmission field. To operate in coordination with four-way handshake and proposed NMST (neighbor MP status table), nodes can access channels more efficiently, and to avoid collisions with wrong information from other nodes. The simulation results show that the proposed scheme improves the network throughput over collision based scheme, i.e., EDCA.