摘要
该文对IEEE 80 2 .11协议的DCF功能进行了研究 ,在分析原有的DCC算法的基础上 ,对其进行了改进 ,提出了一种增强型的DCC算法———EDCC算法 .原有的DCC算法虽然能够有效地减少高负荷网络中各节点接入共享信道的碰撞次数 ,但其没有有效地利用高负荷网络中连续两次发送时隙利用率的相关性对时隙利用率进行平滑处理 ,导致对时隙利用率的估值与现实中的结果存在偏差 .改进后的EDCC算法采用一维自回归滑动平均模型ARMA(α)平滑处理的方法 ,改进了原有DCC算法对时隙利用率估计方差较大的缺点 ,提高了DCC算法的性能 .
This paper presents a novel algorithm, called Enhanced Distributed Contention Control algorithm, for improving the performance of DCF (Distributed Coordination Function) Operations of IEEE 802.11 Wireless LAN (WLAN). EDCC algorithm is an extension of the existing IEEE 802.11 DCF Medium Access Protocol (MAC) by estimating the values of slot utilization and contention degree. Recent research shows that the IEEE 802.11 backoff mechanism has one main drawback: in a high load network the increase of the CW_SIZE is obtained at the cost of a continuous collision after a successful transmission because no state information indicating the actual contention level is maintained. The DCC (Distributed Contention Control) mechanism can solve the problem by estimating the value of network’s slot utilization and using it to schedule itself transmitting action. But the DCC mechanism doesn’t think of the correlation of slot_utilization when a node transmits two successive frames in a high load network. As a result, the distortion of the slot utilization’s estimation is big. The Enhanced DCC algorithm reduces the distortion of estimating slot utilization by using an ARMA( α ) Filter method to utilize the successively estimated value of slot utilization. At the same time, EDCC algorithm keeps the main characteristics: simplicity, integrability, complete distribution, adaptiveness and no transmission overhead. Results show that the EDCC algorithm can provide higher channel utilization and a lower network load compared with DCC algorithm.
出处
《计算机学报》
EI
CSCD
北大核心
2005年第1期25-34,共10页
Chinese Journal of Computers
基金
国家自然科学基金委和微软亚洲研究院联合资助项目基金 (60 3 72 0 48)
高等学校优秀青年教师教学科研奖励计划基金
国家自然科学基金重大项目基金 (60 4963 16)第 6子课题
教育部科学技术研究重点项目基金 (10 4171)
国家"八六三"高技术研究发展计划
