WCDMA系统中的差分最小均方误差多用户检测算法

Multiuser Detection Algorithm Based on Differential Minimum Mean Square Error Criterion in WCDMA System

宽带码分多址(Wideband code division multiple access,WCDMA)系统中现有的自适应多用户检测算法需要训练比特,不能适应快衰落信道。本文根据WCDMA系统中特有的二级扩频体制的特点,提出基于差分最小均方误差(Differential minimum mean square error,DMMSE)准则的自适应多用户检测算法。该算法根据相邻接收符号幅度变化的比率变化自适应调整横向滤波器的权系数,从而不需要通过训练比特开销跟踪信道状态信息的方式来抑制多址干扰。仿真结果表明,在存在多普勒频移的传播环境下,DMMSE算法的误码性能优于现有的自适应最小均方误差(Minimum mean square error,MMSE)算法。

Since the existing adaptive algorithms need training bits and are unsuited for fast fading channel in wideband code division multiple access （WCDMA） systems, an adaptive multiuser algorithm based on differential minimum mean square error （DMMSE） criterion is presented. According to the typical characteristic of two-layer spreading modulation in the WCDMA system, the proposed DMMSE criterion updates the weighing coeffient of transversal filter by tracking the ratio of successive symbols. By avoiding the task of obtaining orthogonal vari- able spreading factor （OVSF） of other users, the proposed method can rapidly track varying fading gains. Theorital analysis and simulation results illustrate that DMMSE performs better than that of the existing algorithms in the Doppler shift channel.