NS2中802.11Ext模块多速率选择机制研究与实现

深入分析了网络模拟器(network simulator version 2, NS2)中新开发的IEEE 802.11协议模块（简称802.11Ext）的模块化设计、累积信干噪比计算、媒体接入控制帧捕获能力、支持多种调制方式、物理层丢包跟踪机制、Nakagami衰落模型等特点，详细阐述了基于802.11Ext模块进行网络模拟时的信号流程。尽管802.11Ext模块在物理层支持多种数据发送速率，但是该模块并没有实现信道自适应的多速率选择机制，鉴于此，研究并实现了802.11Ext模块的信道自适应多速率选择机制。模拟结果表明，在802.11Ext模块中实现信道自适应的多速率选择机制后,链路吞吐量提高了4.7倍、分组时延减少88%。

Implementation of multi-rate selection mechanism for the extended IEEE 802.11 model in NS2

The extended IEEE 802.11 model in NS2(network simulator version 2) is described,which has the key features of the structured design of functionality modules,cumulative signal to interference plus noise ratio computation,media access control frame capture capabilities,multiple modulation scheme support,packet drop tracing,and Nakagami fading model.Although the extended IEEE 802.11 model supports multi-rate at physical layer,it does not implement the channel adaptive multi-rate selection mechanism.After analyzing the signal flow of the extended IEEE 802.11 model,the mechanism is implemented.The simulation results demonstrate the link throughput improves 4.7 times and packet delay decreases 88% after implementing the channel adaptive multi-rate selection mechanism.