关键词: 无线局域网，点协调功能，自适应差额轮询，网络模拟器，服务质量

Abstract: A adaptive deficit polling scheme was put forward which aimed to guarantee the QoS(Quality of Service) of Round Robin polling scheme under the condition of inefficient WI_AN IEEE 802. 11 PCF (Point Coordination Function) mechanism. The core idea of this scheme was described as well as the processing of adjustment mechanism, and it was simulated on the platform of network simulator NS-2 by revising PCF source code. I}hc results indicated that adaptive deficit IEEE 802. 11 PCF polling scheme is prior to Round Robin scheme with its better performance of QoS(Quality of Service) which includes end-to-end delay, system throughput, packet delay, etc.

Key words: WALN, PCF, Adapive deficit polling scheme, NS-2，QoS