衰落信道中 Q-CDMA 系统差错性能的理论分析与仿真

Theory Analysis and Simulation of Q CDMA Systems in Fading Channels

在移动无线通信领域中，许多已获得的测量数据表明：在城市蜂房移动通信中，多径衰落信道符合Ｎａｋａｇａｍｉ分布。本文通过理论分析和计算机仿真，研究了在Ｎａｋａｇａ－ｍｉ频率选择性多径衰落信道中，应用相干ＲＡＫＥ接收时，ＢＰＳＫ和ＱＰＳＫ直接序列码分多址扩频通信系统的性能，得到了差错概率理论近似计算表达式。数值计算和计算机仿真结果表明了高斯噪声、多用户干扰、多径衰落以及分集接收等对系统性能的影响。

In the recent study of the mobile radio channel,based on many empirical data,it is suggested that the path fading statistics can be more adequately described by Nakagami distribution especially in urban areas.Through theory analysis and computer simulations, we have analyzed the performance of the BPSK and QPSK DS CDMA system(coherent RAKE receiver model) under the assumption that the channel model is Nakagami frequency selective multipath model. We have gotten the theory expressions of the bit error rate. Numerical and simulation results show that the Gaussian noises, multi user interferences, multipath fading and diversity receiving all have impact on the system performance.