Iterative coded multiuser detection with a Verdu soft demodulator

Two iterative multiuser detection receivers from the literature are considered for a system with multiple convolutionally-coded asynchronous users. Both receivers operate directly on matched-filter outputs with colored noise samples, but one utilizes the Verdu (see Multiuser Detection, Cambridge University Press, Cambridge, UK, 1998) forward-backward detection algorithm, and the other we shall recognize as employing a suboptimal approximation of the Verdu algorithm. The iterative receivers are described in terms of the soft-input soft-output modules for distributed iterative decoding of code networks [1]. The performance of the Verdu-based iterative receiver is simulated for three multiuser examples taken from the literature. Conclusions are made based on empirical results for the equal power and unequal power scenarios.