多径衰落信道中扩频信号处理增益的上限

考虑充分散射多径衰落信道中的时频二维扩频BPSK调制信号,针对联合相干非相干检测算法,寻找扩频信号处理增益的上限。首先给出了扩频信号处理增益的闭合表达式;然后分析当信号带宽无限增大或符号长度无限增大时,扩频信号处理增益不会无限增大;最后得出处理增益的上限由信道参数和信噪比决定的结论。分析与仿真结果表明,BPSK调制、20dB信噪比、100Hz最大多普勒频移、5×10 6负指数衰落因子的充分散射多径信道,扩频信号的处理增益不超过30dB。

Upper processing gain bound of the spreading signal in multipath fading channels

Using the joint algorithm of coherent detection and non-coherent detection,the upper processing gain bound of the spreading signal,which is two-dimensional spread spectrum signal relative to BPSK and transmitted in rich scattering multipath fading channel,was sought.Firstly,the expression of the processing gain of the spreading signal was calculated.Secondly,with increasing signal bandwidth or symbol period unlimitedly,the processing gain was bounded.At last,it was obtained that the upper processing gain bound is determined by the channel parameters and signal noise ratio.By analysis and simulation,the processing gain of the spreading signal,relative to BPSK and transmits in rich scattering multipath fading channel,is not more than 30dB,when the signal noise ratio is 20dB,the maximum doppler shift is 100Hz,and the negative exponential factor is 5×10?6.