基于动态载波侦听的无线网络性能研究

项目名称： 基于动态载波侦听的无线网络性能研究

项目编号： No.61271277

项目类型： 面上项目

立项/批准年度： 2013

项目学科： 无线电电子学、电信技术

项目作者： 刘绍强

作者单位： 香港中文大学深圳研究院

项目金额： 70万元

中文摘要： WiFi网络在现实中无处不在，网络中的设备通过CSMA协议争用无线信道。吞吐量是衡量网其性能的重要指标，而目前计算吞吐量的方法存在两个缺陷：一是运用了复杂的随机过程分析；二是它们基于一个不精确的载波侦听模型从而不能反映真实情况。而本项目就是要致力于弥补这两个缺点，为设计大规模WiFi网络提供理论基础和更优的设计方法。 在前期的研究中我们提出了一种简单的计算吞吐量的方法-BoE算法。对于规模不大的网络，用BoE通过手工计算很快就能得出较精确的结果。对于第二点，几乎现有的研究都假定了一种静态的载波侦听关系，而这并不符合实际的网络情况。实地试验表明由于信道衰落和电路噪声，每个节点对能都侦听到其他节点是随时间变化的，是动态的侦听关系。这个发现对于网络性能的研究具有至关重要的影响。 本课题将首次基于BoE和动态载波侦听模型对大规模CSMA无线网络性能表征重新审视研究。并利用实验验证新的理论结果。

中文关键词： 动态载波侦听；无线局域网；CSMA无线网络；置信度传播；无线自组织网络

英文摘要： It is very common these days to find many Wi-Fi networks being deployed in the proximity of each other. The Wi-Fi devices in these networks compete to use the wireless medium using the CSMA protocol.Throughput is an important index to evaluate the performance of networks. However, the existing throughput computation methods fall short in two regards: (i) they involve complicated stochastic analyses; (ii) they are based on an inaccurate carrier-sensing model that does not reflect reality. This proposal aims to fill the gaps of (i) and (ii), with the ultimate goal of providing insights into superior designs of large-scale CSMA networks. According to our preliminary investigation, we found a simple computation method, which we call back-of-the-envelop (BoE) computation. For modest-size networks, very accurate results can be obtained within minutes, if not seconds, by simple hand computation.Regarding issue (ii), almost all current research assumes that the carrier-sensing relationships among the devices are static. Our real-network experiments, on the other hand, indicate that quite often a device can only hear another device some but not all of the time, due to wireless channel fading and circuit noise.This has significant implications for the network performance. This proposal is a first attempt to re-examine

英文关键词： Partial Carrier Sense；WiFi；CSMA Wireless Networks；Belief Propogation；Ad hoc Wireless Networks