An Iterative Multiuser Detection/Decoding for Nonbinary LDPC Coded MC-MFSK Multiple Access Systems

Abstract

This paper studies an iterative multiuser detection and decoding for nonbinary low density parity check (LDPC) coded multicarrier M-ary frequency shift keying (MC MFSK) multiple access system to increase system spectral efficiency under specific signal-to-noise ratio. At multiuser detection side, soft metric for each symbol is quantized to 2 levels (2L) or 3 levels (3L) and then pass to the decoder. When the soft output of a symbol from decoder exceeds a threshold, the user is declared as a reliable symbol. The reliable information is fed back to the detection side and updates the symbol soft output when iterative processing is carried out. Numerical results show that system spectral efficiency is improved for 3L system over Rayleigh fading.