M-ary 正交调制 DS/CDMA 在衰落信道中的性能分析

Performance analysis of noncoherent M ary DS/CDMA in fading channel

讨论了Ｍ－ａｒｙ正交调制ＤＳ／ＣＤＭＡ系统在瑞利及莱斯衰落下的误码性能。采用理论分析的方法，推导出了在瑞利及莱斯衰落下ＤＳ／ＣＤＭＡ系统误码率的闭式表达，理论分析与数值积分结果相符。对于实际信道功率时延曲线为指数衰减的情况，讨论了不同指数衰减率对系统性能的影响，并就分集接收方案及不同系统参数的影响也作了分析。结果表明随着指数衰减率的增加和莱斯参数的减小，误码逐渐增大；而随着分集的加入，系统误码性能可大大改善。

M ary orthogonal modulation is a spectrum efficient modulation scheme suited for the reverse link of DS/CDMA system. This paper analyzes the performance of M ary DS/CDMA in multipath fading channels with Rayleigh and Rician fading distribution. A noncoherent Rake receiver structure with equal gain combining is used for demodulation. Through theoretical derivation, closed from formulae of bit error rate (BER) are achieved for both Rayleigh and Rician fading, which match the numerical results very well. The system performance is evaluated in terms of various exponential decay rates and Rician factor for the case of exponential power delay profile. Finally, diversity effects are considered with the effects of different system parameters.