Blind multiuser detection for space-time coded CDMA systems

We propose here a linear blind multiuser detector, referred to as the Capon receiver, for space-time coded CDMA (code division multiple access) systems. The proposed Capon receiver is designed to pass desired signals without distortion, meanwhile minimizing the overall interference signals, irrespective of their origins. It is shown that the Capon receiver achieves similar performance in terms of the output SINR (signal-to-interference-and-noise ratio) to that of the optimum, linear, training-assisted MMSE (minimum mean squared error) receiver over a wide range of the input SNR (signal-to-noise ratio). It is also shown that the ratio of the output SINR of the Capon receiver to that of the MMSE receiver converges to a constant very close to one at high SNRs. The Capon receiver also yields a blind channel estimate which converges to the true channel parameters (within a scalar ambiguity) as the SNR increases. Simulation results are provided to support our study.