On optimal Adaptive Contention Window Control in Wireless LAN

• Main Authors: Mao-Shih Chen, 陳楙仕
• Other Authors: Huan Chen
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/87373408324971114881

碩士 === 國立中正大學 === 電機工程所 === 94 === In the IEEE 802.11 standard, MAC layer provides the Distributed Coordination Function, in which the Binary Exponential Backoff (BEB) mechanism is used for the contention control. BEB attempts to randomly select the backoff time slots before they can transmit data. Such mechanism efficiently avoids multiple stations to transmit data at the same time, and thus reduce the collision probability. However, the conventional BEB does not perform well when traffic is heavy because under such traffic condition collision occurs frequently, which results in serious delay as well as low. The emphasis of this thesis is on the development of a novel backoff mechanism, the Optimal Backoff (OB) mechanism. Proposed OB can choose an optimal contention window and thus efficiently avoid the collision problem under both light and heavy traffic scenario. Both the analytical and simulation results have confirmed that the proposed OB algorithm can find an optimal contention window according to different traffic load and thus achieve high throughput, low delay as well as low collision probability.