An improved successive interference cancellation multiuser detector for narrowband signals

This paper examines the possibility of reducing error propagation in the successive interference cancellation multiuser detector (SIC-MUD) for a narrowband system. A simple sequence estimation algorithm is employed, working on a symbol by symbol user basis, not affecting the operation of FEC decoding if present. Operating along the stages of the SIC-MUD scheme, this algorithm has a complexity that increases only linearly with the number of users and thus can be used for a larger number of users, as against the optimum joint detection-MUD (JD-MUD), whose complexity increases exponentially with the number of users. Investigation is carried out for both AWGN and Rayleigh fading channels. The obtained results show that the Improved SIC-MUD scheme reduces the error propagation considerably and, with its low complexity, can be a good alternative for the JD-MUD scheme.