融合QoS与负载均衡的基础服务集信道分配算法

针对目前在同一热点区域内高密度部署无线接入点(AP)造成的信道干扰问题，该文结合同一个基础服务集(BSS)内终端的服务质量(QoS)和BSS间的负载均衡的需要，分析了基于IEEE 802.11e的3维离散马尔科夫链模型，并修订了其中竞争窗、退避计数器以及重传次数的量化关系，完善了该模型，得到了更为准确的基于QoS的终端归一化吞吐量表达式；其次，在信道分配设计时，既考虑了每个BSS内终端和AP之间通信的QoS，又考虑了每个AP范围内所有与之关联的终端受到相邻AP信道干扰下整体吞吐量的公平性，并对信道干扰进行了分析，将信道分配问题建模为一个最优化问题。最后，通过遗传算法获得了AP之间的最优信道分配。数值分析结果表明，基于公平和服务质量的信道分配方法CAFQ与Hsum和CAOTR算法相比，可以使BSS间的互干扰最小，BSS内基于QoS的吞吐量得到最大的保证，同时在BSS间的负载均衡方面也体现了较好的公平性。

Integrated QoS and Load Balance among Basic Service Set for Channel Allocation Algorithm

Wireless Access Points(APs) deployed in the same hotspot with a high density will cause channel interference.Considering this issue,also combined with the QoS of terminals in the same Basic Service Set(BSS) and the load balance among different BSS,a three-dimensional discrete Markov chain model based on IEEE802.11e is analyzed.The quantitative relationship of contention window,backoff counter and retransmission number is revised.Besides,a more accurate normalized terminal throughput expression based on QoS is obtained,and the mentioned model is consummated.Secondly,when designing channel allocation,both the QoS of the communication between the terminals within each BSS and AP and the fairness in overall throughput of the terminals within each AP which associated with it and interfered by adjacent AP channel are considered.Also,modeling analysis of channel interference is adopted and the channel allocation issue is ascribed to an optimization issue.Finally,the optimal channel allocation among AP is obtained by genetic algorithm.Numerical analysis results show,compared with Hsum and Channel Assignment based on the Onder of Throughput Reduction CAOTR algorithms,the proposed Channel Assignment based on Fairness and QoS(CAFQ) algorithm based on generic algorithm can minimize the mutual interference among BSS and make a maximum guarantee of the throughput based on QoS within each BSS.Simultaneously,a relatively good fairness in load balance among BSS is obtained.