On multiuser detection in noncoherent CDMA channels

The problem of noncoherent demodulation of differentially phase-shift keyed signals over an additive Gaussian code-division multiple-access (CDMA) channel is considered. A minimax robust multiuser detection strategy which optimizes the worst-case multiuser asymptotic efficiency over the interfering signal energies and phases is derived. In the limit as the packet length tends to infinity, this detection is shown to be equivalent to a time-invariant K-input, K-output decorrelating filter followed by a time-invariant differential decision logic. The significant property of this detector is its invariance of error probability to the interfering signal energies and phases, thereby alleviating the near-far problem