OFDM-WLAN系统的物理层建模与仿真

Modeling and Simulation for the PHY of the OFDM-based WLAN System

基于IEEE 802.11a无限局域网标准,对OFDM(正交频分复用)-WLAN(无线局域网)系统物理层中的各个模块进行了数学建模,并对其性能进行了计算机仿真。定性分析了载波频偏、定时偏差和衰落信道对OFDM-WLAN系统性能的不利影响;根据IEEE 802.11a标准中的分组结构形式,利用长、短训练序列分别对载波频偏估计、定时偏差估计以及信道估计进行了算法建模及理论分析,给出了三种估计算法的数学表达式;通过Monte-Carlo数值仿真方法对上述3种算法进行了验证和定量评估,仿真结果证明了算法的有效性。

Based on the IEEE802.11 a standard, the fundamental parts at physical layer of the OFDMbased WLAN system are modeled and simulated in this paper. Firstly, three key issues such as CFO（ Carrier Frequency Offset）, timing offset and fading which will degrade the OFDM-WLAN system＇s performance are analyzed theoretically. Then, according to the frame structure of IEEE802.11 a, three algorithms corresponding to CFO estimation, timing synchronization and channel estimation are proposed and discussed respectively. And the mathematical expressions of them are given. Finally, Monte-Carlo simulations are done to verify the effectiveness of the estimation algorithms proposed.