马尔可夫链模型下的扩频Ad Hoc网络性能  

Performance of Spread Spectrum Ad Hoc Networks Based on Markov Chain Model

作　　者：孙诗东[1] 聂景楠[1,2] 

机构地区：[1]解放军理工大学通信工程学院,江苏南京210007 [2]东南大学移动通信国家重点实验室,江苏南京210096

出　　处：《应用科学学报》2008年第6期562-568,共7页Journal of Applied Sciences

基　　金：国家自然科学基金资助项目(No.60503049);东南大学移动通信国家重点实验室开放课题基金(No.200602)资助项目

摘　　要：通过引入排队系统和马尔可夫链建模方法,建立非时隙扩频ad hoc网络理论分析模型,导出了数据分组成功传输概率,得到了系统吞吐量和时延性能表达式.在此基础上,分析了接收信号信噪比、分组长度、扩频增益对网络吞吐和时延性能的影响,给出了仿真和数值计算结果.结果表明:当信噪比较低时,提高信噪比是增强网络性能的有效途径.然而,当信噪比提高到30 dB后,再继续提高信噪比无助于改进网络性能,而降低分组长度有利于提高网络吞吐和时延性能.此外,提高扩频增益虽有利于改善网络时延性能,但是由于要增加扩频信号传输对带宽的消耗,因而需要合理选取扩频增益使归一化吞吐性能达到最优.An analytical model for performance evaluation of unslotted spread spectrum ad hoc networks is presented by introducing a queuing system and a Markov chain. The model is used to derive packet success probability and expressions for calculating throughput and delay. Based on the derived expressions, the impacts of received SNR, packet length, and spreading gain are discussed in terms of throughput and delay. Numerical results show that a significant improvement in throughput and delay can be obtained by raising SNR at low SNR. However, raising SNR does not improve performance further when SNR 〉 30 dB. Nonetheless, throughput and delay can be improved by reducing the packet length. In addition, improvement of delay performance is acquired when the spreading gain increases. There is an optimal value of spreading gain to maximize the normalized throughput due to the fact that spread spectrum transmission occupies an additional bandwidth.

关 键 词：扩频ad HOC 吞吐量 传输时延 马尔可夫链 

分 类 号：TN914.42[电子电信—通信与信息系统]