NS-2无线物理层实现与衰落功能扩展研究  

Study on NS-2 Wireless Physical Layer Implementation and Fading Function Extension

作　　者：王悦[1] 刘灿涛[2] 朱雷[1] 张书云[1] 

机构地区：[1]中央财经大学信息管理系,北京100081 [2]中央财经大学计算机科学与技术系,北京100081

出　　处：《计算机工程》2014年第7期58-61,共4页Computer Engineering

基　　金：国家自然科学基金资助项目(61309030;61100112);教育部人文社会科学研究青年基金资助项目(11YJCZH006);北京市哲学社会科学规划基金资助项目(12JGA014;13JGA004);中央财经大学学科建设基金资助项目

摘　　要：通过跟踪源代码,分析NS-2无线物理层的C++类,对NS-2分组收发仿真实现原理进行研究。针对NS-2仅实现理想信道而未考虑信道衰落效应的问题,给出扩展信道衰落功能的一般计算步骤,并以瑞利衰落为例在NS-2无线物理层中实现。UDP和TCP传输性能在引入瑞利衰落后有较大不同,体现了无线传输的不确定性。单链路的吞吐量随链路长度增加而下降;在无线局域网中,距离AP远的节点受衰落效应影响大,吞吐量下降;距离AP近的节点受衰落效应影响小,共享带宽占用了前者的剩余带宽,吞吐量反而上升。仿真结果显示,NS-2信道衰落功能扩展有助于准确验证无线网络协议性能。This paper studies the implementation of packets transmission and reception of the NS-2 wireless physical layer by tracing its C＋＋ classes, which offers a guideline to extend the NS-2 wireless functionality. As NS-2 only implements an ideal channel without considering channel fading, the paper gives the general computation method of fading in NS-2 and implements Rayleigh fading as an example. The performance of UDP and TCP flows under Rayleigh fading is different from those without fading, which simulates the uncertainty of wireless transmissions. The throughputs of a single link decrease as the link length increases. In Wireless Local Area Networks（WLAN）, the throughputs of the nodes far from the AP are affected significantly by fading causing throughputs degradation, while the throughputs of the nodes nearby the AP are affected slightly by fading and its throughput increases due to bandwidth sharing. Simulation result shows that the fading extension in NS-2 makes wireless network protocols more accurately than before.

关 键 词：NS-2网络模拟器 信道衰落 吞吐量 公平性 物理层 802 11无线局域网 

分 类 号：TP393[自动化与计算机技术—计算机应用技术]