滤波法与频谱法在瑞利衰落信道仿真中的比较研究

Comparison Study on Rayleigh Fading Channel Simulation Using Filter Method and Spectrum Method

本文运用滤波法和频谱法仿真了带Clarke多普勒频谱的瑞利衰落无线信道,基于功率谱密度(PSD),分别计算了两种方法下获得的电平通过率(LCR)和平均衰落时延(AFD)。仿真结果显示,两种方法具有非常接近的电平通过率和平均衰落时延,频谱法在仿真时间上优于滤波法。但当采样数量增大时,滤波法优于频谱法。本文还通过仿真观察了不同信道阶数和多普勒频率下的瑞利衰落信道的时频变化特性。

We have simulated a Rayleigh fading wireless channel with Clarke’s Doppler spectrum using two methods,filter method and spectrum method.Based on Power Spectral Density(PSD),Level Crossing Rate(LCR)and Average Fade Duration(AFD)we evaluated the results obtained from the two methods.We obtained very similar results from both of them compared to the theory.The filter method is however more complex in terms of simulation time compared to the efficient spectrum method.The filter method gives better results compared to spectrum method when numbers of samples are taken very large.We have also simulated the channel for different taps and Doppler fre⁃quencies to observe time-frequency varying behavior of a Rayleigh fading channel.