Single- and multi-user blind receivers for long-code WCDMA

In previous work, Tong, Van der Veen e.a. derived a blind decorrelating receiver and channel estimation algorithm for long-code (aperiodic) wideband CDMA systems. Although its performance in the presence of multiaccess interference is usually much better than the conventional matched filter (RAKE), in heavily loaded systems its performance is dearaded because the decorrelating step colors the noise. In this paper, we propose both single-user and multi-user blind source-channel estimation algorithms by making use of an iterative estimation scheme combined with a decorrelating RAKE receiver (DRR) as the initial channel estimate, which takes the noise color into account. The conventional RAKE receiver is also considered as an alternative for the initial channel estimation. The algorithm when multiple received antennas are used at the base station is also developed. Simulation results show significant improvements, even in heavily loaded systems.