Subspace-based multiuser detection for DS-CDMA systems with correlated noise

Two subspace-based multiuser detectors are presented for a synchronous DS-CDMA system operating over a multipath fading channel with correlated noise. Based on the training sequence transmitted by the desired user and employing a noise whitening process, a linear MMSE detector is obtained which does not require knowledge of the code sequences and the propagation channel response. When the training sequence is not available, a matrix decomposition method is adopted to estimate the channel response. Through signature waveform estimation, a linear MMSE detector can be obtained blindly. Simulation results show that these two methods are robust against the near-far problem and the correlated noise