基于时隙选择概率分布的DCF区分服务机制

Differentiated Services Mechanism Based on PDoSS in DCF

针对IEEE 802.11 DCF不能为实时业务提供服务质量保证的问题,提出一种简单的基于优先级的退避机制,根据不同等级数据业务的QoS需求提供区分服务。高优先级数据流采用减少数据包重传次数策略,低优先级数据流采用改进的RWBO+BEB退避机制,使得时隙选择概率分布均匀,能减少数据包碰撞概率。采用马尔科夫链模型对该机制进行数学分析与评价,结果表明,该机制不仅能够有效支持区分服务,并且能够提高系统饱和吞吐量。

Considering that 802.11 DCF does not support any Quality of Service（QoS） for real-time traffic, this paper proposes a novel and simple priority-based backoff scheme to provide service differentiation according to different QoS requirements from different classes of traffic. For high-priority data flow, a strategy of reducing retransmissions is adopted. For low-priority data flow, an improved RWBO＋BEB backoff algorithm is introduced to make the Probability Distribution of Slot Selection（PDoSS） even, and thus to reduce the packet collision probability. A Markov chain model is deployed and used to analyze and evaluate the mechanism performance. The mathematical analyses demonstrate that the proposed mechanism can support QoS in 802.11 DCF effectively, moreover, improve the overall system performance significantly.