Computer Engineering and Applications ›› 2007, Vol. 43 ›› Issue (20): 132-135.

• 网络、通信与安全 • Previous Articles     Next Articles

ADD:MAC contention window backoff algorithm in wireless LANs

SONG Yi,WANG Jian-xin   

  1. School of Information Science and Technology,Central South University,Changsha 410083,China
  • Received:1900-01-01 Revised:1900-01-01 Online:2007-07-11 Published:2007-07-11
  • Contact: SONG Yi


宋 翊,王建新   

  1. 中南大学 信息科学与工程学院,长沙 410083
  • 通讯作者: 宋 翊

Abstract: Design of Medium Access Control(MAC) protocols is one key problem in Wireless Local Area Networks(WLANs).The major features of a MAC protocol are high throughput and good fairness.In this paper,we propose a new efficient Contention-Window(CW) resolution mechanism,called Adaptive Double increase double Decrease algorithm(ADD),according to the IEEE 802.11 Distributed Coordination Function(DCF),which improves the performance of original MAC protocol.The algorithm is developed as follows:each station will halve the contention window after n consecutive successful transmissions,and the value of n is adjusted adaptively according to the throughput of AP node.This algorithm can reduce the collision probability;meanwhile,it improves the fairness between different stations.

Key words: WLAN, Medium Access Control(MAC), backoff algorithm, contention window

摘要: 在无线局域网(WLANs)中,介质访问控制(MAC)协议的设计是一个核心的问题。MAC协议应该满足较高的吞吐量和较好的公平性等要求。根据802.11分布式协同函数(DCF),提出了一种新的高效的竞争窗口(CW)处理机制,称作自适应倍乘增加倍乘减小算法(ADD)。该算法的基本思想如下:每个站点在成功地连续发送n个数据包后,其MAC层的竞争窗口减小为原值的一半,而且n的值根据接入节点(AP)的瞬时流量自适应地调节。大量仿真实验表明:该算法可以通过有效地降低站点之间的冲突概率,来增加系统整体的吞吐量,同时增加不同站点之间的公平性。

关键词: 无线局域网, 介质访问控制, 退避算法, 竞争窗口