摘要:在众多的IEEE 802.11 DCF机制分析模型中，集中分析了同质业务（例如数据包到达速率相同）网络的性能，仅有少量的文献聚焦于异构混合业务（饱和与非饱和工作模式同时存在）网络，而在目前的研究中，对网络的不饱和性及退避时隙冻结等问题归纳分析得并不准确.结合M/G/1排队模型，考虑了DCF机制的退避冻结状态及有限的重传次数等问题，提出了一种全新的改进二维Markov链路模型，用于分析异构混合业务成分下的DCF机制的性能.通过对模型的稳态求解，提出的模型能够分析并计算协议中的3个重要的参数：系统吞吐量、传输时延和传输丢包率.理论仿真与分析结果表明，该模型不仅能够更为准确地分析同质业务下DCF机制的性能，同时充分考虑到了实际应用中的业务情况，还能够更准确、更完善地分析异构混合业务成分下的DCF机制的性能.



Abstract:Most IEEE 802.11 DCF analysis models concentrate solely on the performance of homogeneous traffic sources (i.e., with the same arrival rate), only a small number of literatures focus on heterogeneous mixed service networks (i.e., saturated or nonsaturated). In current research, the network nonsaturated and backoff freezing analyses are not accurate. This study proposes a new and improved bi-dimensional Markov chain model to analyze the performance of the DCF mechanism under heterogeneous traffic sources with the M/G/1 queuing model. Moreover, it extends the existing models to take into account previously-ignored MAC layer factors such as backoff freezing and limited times of retry. By solving the steady-state of this model, it allows the calculation of the three important parameters:per-station and network throughput, mean delay, and transmission packet loss. Through the relevant theoretical simulation and analysis, it is proved that the model can well analyze the performance of the DCF mechanism, taking into account the actual application scenarios, thus can analyze the performance of the DCF mechanism better than others under heterogeneous traffic sources.



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