Study on IEEE 802.11s MDA Reservation Mechanism for Weighted Adjustment Scheduling Algorithm in Multi-channel for Wireless Mesh Network

• Main Authors: MING-CHE HSU, 許銘哲
• Other Authors: Bih-Hwang Lee
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/s48r65

碩士 === 國立臺灣科技大學 === 電機工程系 === 100 === A wireless mesh LAN is a communications network made up of radio nodes that support Mesh service. 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. In a previous study, it was suggested so that MDA can operate on multi-channel environment. Compared with the MDA, MMDA does effectively enhance the system performance. In addition, there has a research study on MMDA in high loading situation. The data transmission period has been reserved to the saturation, and it can dynamically allocate Contention Period ratio to increase date Transmission Period. So it helps to reserved more MDAOP to improve system performance. However, in multi-hop network environment, each mesh nodes transmission data are first-in-first-out sorting mechanism. Thus, when the high hop-count data is in the forwarding process, it’s also arranged in a queue behind the position. When the network load becomes heavy, high hop-count of transmission opportunities will be reduced. Hence, discard probability will improve. Besides, the high hop-count data re-transmission cost is also higher than the low hop-count. This result will cause the waste of network resources and unfairness. In order to solve the above problems, we propose a dynamic adjustment of the sorting queue. The method considers data Time-to-live (TTL), and MeshRetryTimeout to do the adjustment factors. This thesis hopes to increase the transmission performance of high hop-count to achieve balance of the network system.