分析IEEE802.11e的服务质量(QOS)调度机制,讨论了IEEE802.11e协议给出的简单调度算法(Simple Scheduler)及其支持可变比特速率业务(VBR)时存在的不足。对简单调度算法进行了改进,提出一种适用于实时VBR业务的调度算法,该算法可以动态地调整服务间隔、每个业务流的发送机会周期(TXOP)。在NS网络模拟器上实现了适用于VBR业务的HCCA调度算法,并进行模拟仿真,对两种调度算法的性能进行比较。仿真结果表明,该机制有效改善了延时和传输效率。
The Quality Of Service(QOS) scheduling mechanism of IEEE802.11e is analyzed,and the simple scheduling algorithm(Simple Scheduler) and its deficiencies existing in supporting Variable Bit-Rate service(VBR) are discussed.And then an improved algorithm which adapts to the real time VBR service is proposed.The algorithm can dynamically adjust the service interval and the TXOP of per flow.Finally,the algorithm on NS2 is implemented.Compared with the HCCA,simulation results show that this mechanism effectively improves the delay and transmission efficiency.