Constrained detection for noncoherent nonlinear multiuser communications

We consider noncoherent multiuser detection techniques for a system with users employing nonlinear modulation using non-orthogonal signals. Our aim is to investigate near-optimum noncoherent multiuser detection techniques that utilize the structure of the received signals while retaining reasonable complexity. We explore detectors that are derived using nonlinear programming approximations of the maximum likelihood multiuser detector as well as soft interference cancellers. We also propose a class of detectors called the partial detectors which improve the performance of the decorrelator and MMSE type detectors. We evaluate the proposed detectors' performance to provide numerical comparisons.