无线局域网物理层协议仿真建模

Modeling of Physical Layer Protocol of WLAN for Simulation

在仿真环境下评价和改进网络性能的主要工作是设计和实现网络协议的模型。由于现在的网络仿真器大都基于离散事件驱动模型和TCP/IP协议栈体系结构,所以物理层协议仿真模型的建立成为评价上层协议性能的前提。但是现有网络仿真器提供的物理层协议模型主要针对有线网络,所以没有考虑无线信道的特性。基于无线信号传播模型和有限状态自动机理论,提出了无线局域网物理层协议仿真模型的设计思路和在具体的网络仿真器中实现IEEE 802．11b协议的方法。建立的模型能够比较真实地模拟无线局域网物理层所具有的发送信号、接收信号和载波侦听的功能。

To estimate and improve the performance of networks in the simulation environments, the main task is designing and implementing the model of network protocols. Since most of current network simulators are based on discrete event driven model and are built on the architecture of TCP/IP protocol stacks, design and implementation of the simulation model of physical layer protocol are the prerequisites for estimating the performance of upper layer protocols. However, physical layer models in current simulators are specifically for wired networks and rarely take characteristics of wireless channel into consideration. Based on the Radio Propagation Model and Finite State Machine, this article proposes the route to establish the simulation model of physical layer protocol of WLAN, and the approach to implement the IEEE 802.11 b protocol in a specific network simulator. The established model can vividly simulate the basic functions of physical layer of WLAN such as signal transmitting, signal receiving and carrier sensing.