Varying length equalizer for WCDMA system

In the downlink of synchronous CDMA, the orthogonality of spreading codes will be ruined by the frequency selective multipath channel. Losing of orthogonality causes the multiple access interference (MAI). To suppress the MAI, linear equalizers were proposed which can partially restore the orthogonality of spreading codes before dispreading. In this paper, a new adaptive equalizer using the least mean square (LMS) algorithm was proposed which can adjust its length according to the condition of the propagation channel. The simulation results show that the performance of the new equalizer is significantly better than that of the conventional RAKE receiver.