PERFORMANCE COMPARISON OF NON-LINEAR INTERFERENCE CANCELLATION TECHNIQUES FOR MULTIUSER DETECTION IN DS-CDMA SYSTEM

Abstract

Direct sequence code division multiple access (DS-CDMA) is a most popular mobile communication technology. In DS-CDMA communication, signals of all users overlap in time and frequencies and cause multiple access interference (MAI). The conventional DS-CDMA detectors follow the single user matched filter detection technique, in which each user is detected individually without regard for other users and ignores the existence of MAI. Its performance is not very satisfactory and is particularly limited by the near-far problem. Multi-user detection is the efficient technique to use the capabilities of code-division multiple access (CDMA), which is becoming the ubiquitous air-interface in future generation communication systems. The problem of multiple access interference (MAI) is vital for a CDMA system. The different types of multi-user detectors have been proposed to mitigate the MAI. The different sub optimal multi-user detector offers performance in between the single user matched filter and the optimal multiuser detectors with substantially reduced complexity. This paper presents the simulation results regarding performance comparison of some most popular non-linear multi-user detectors i.e., multistage detectors, decision- feedback detectors and subtractive interference cancellation.