A comparative analysis of linear multiuser detectors for fading multipath channels

In this paper, we compare two linear multiuser receivers for synchronous CDMA frequency-selective Rayleigh fading channels. The first receiver consists of a bank of matched filters followed by a linear transformation and an optimal combiner for each user. The second consists of a bank of RAKE receivers followed by a linear transformation. We consider receivers for both coherent and differentially coherent PSK demodulation. While the conventional single-user receiver´s performance is severely limited by near-far effects in the multiuser environment, both of these multiuser receivers mitigate the near-far problem and provide significant performance gains for moderate to high SNRs. It is shown that the second receiver has a uniformly lower error rate than the first and that its performance gains relative to the first increase as the number of users and received multipaths increases