初始判决指导的DS／CDMA最大似然检测算法

本文首先给出了多径异步多用户ＤＳ／ＣＤＭＡ系统的一种数学模型，得出了恒参信道下最大似然检测（ＭＬＳＥ）算法的一种新的表示形式，然后作者具体分析了以ＲＡＫＥ接收机作为衰落信道的匹配滤波器时，最大似然检测器的算法设计问题，分析指出，在多径环境下ＭＬＳＥ算法的复杂度和计算量与多径时延的分布有关，如果有用户时延扩散在一个信息码元之内，算法复杂度和恒参信道下相同，而其实现可以用状态中变的Ｖｉｔｅｒｂｉ算法来

Initial Decision Directed MLSE Multi-user Detection of DS/CDMA Signals

In this paper, the system model for multi-user asynchronous DS/CDMA under multi-path fading channel is presented firstly. Then the Maximum Likelihood Sequential Estimation (MLSE) algorithm under time-invariant channel is described in a new form which is different from Verdu's work. Using RAKE receiver as the fading channel match filter, we detailed the MLSE algorithms of the multi-path CDMA signals. Analyses show the computational complexity of our algorithms is determined by the delay spread. If the time delay spread is within one information bit, the MLSE algorithms under multipath fading channel has the same complexity as that under time-invariant channel, and the algorithms can be implemented by Dynamic Programming Algorithms with various state number. Finally, we use the initial decision derived from conventional receiver to reduce the searching space of the Viterbi algorithms. The complexity of the new algorithm is reduced dramatically while the overall performance is still guaranteed.