A Low Complexity Iterative Groupwise Soft Multiuser Detection for Multirate MC-CDMA

This paper addresses a low complexity multi-rate multiuser detector (MUD) for the uplink multi-carrier code division multiple access (MC-CDMA) systems. The new MUD is an iterative groupwise receiver with the assistance of soft information to refine the interference estimates to enhance the interference cancellation capability. The users are first classified into different groups according to their transmission rates. In each iteration, these groups of users are detected sequentially based on a set of group detectors with the removal of multiple access interferences (MAI) group by group, where the soft information is utilized to render more precise interference estimates for more effective cancellation of interferences. To alleviate the computational overhead, the users in each group are further partitioned into appropriate subgroups based on their effective channel correlations and then detected in parallel by a bank of minimum mean-squared error (MMSE) filters. Simulations show that the proposed MUD, with drastically reduced computations, can render satisfactory performance compared with previous works .