虚拟空闲时间对非饱和状态DCF性能的影响  

Effects of Virtual Idle Time on Non-saturated DCF Performance

作　　者：彭春华[1] 徐湘淄[1] 

机构地区：[1]中南大学信息科学与工程学院,长沙410075

出　　处：《计算机工程》2015年第1期96-102,共7页Computer Engineering

摘　　要：研究非饱和状态下分布式协调功能(DCF)协议的性能,针对非饱和状态下的无线局域网,引入虚拟空闲时间定量描述系统的忙碌程度,对二维马尔科夫链模型进行改进。在理想信道条件下,使用基本接入方式,利用改进模型研究虚拟空闲时间及站点数对DCF性能(系统吞吐量和分组传输平均时延)的影响。理论推导及仿真结果表明,在不同的虚拟空闲时间下,随着站点数的增加,系统非饱和吞吐量为先快速上升后缓慢下降的过程,分组传输时延则是平稳上升的过程,与选取的对比模型相比,吞吐量在站点数目较小时有明显改善,时延性能有较大提高。To evaluate the performance of the Distributed Coordination Function（DCF）in the case of non-saturation state,the concept of Virtual Idle Time（VIT）is introduced. It is used to measure how busy the non-saturation Wireless Local Area Network（WLAN）system is. An improved two-dimensional Markov chain model is proposed. With ideal channel and basic access mechanism,the improved Markov chain model is used to investigate the effects of VIT and the number of stations on the system＇s throughput and average package delay. Theoretical analysis and simulation results show that in different VIT,as number of stations increases,the non-saturation throughput decreases slowly after a rapid rise,while the average package delay experiences a steady rise in the process. Compared with the models selected,when the number of station is small,the performance of throughput becomes better,and the performance of package delay is greatly improved.

关 键 词：无线局域网 马尔科夫链 分布式协调功能 虚拟空闲时间 吞吐量 时延 

分 类 号：TP393.17[自动化与计算机技术—计算机应用技术]