Adaptive multiuser detection with decision feedback equalizer for interference cancellation

Multiple access interference (MAI) is considered the major air interference for the 3G radio communication systems in which code division multiple access (CDMA) technique is used for allocating certain number of users the same channel at the same time. Canceling MAI is a major task in the 3G system. Multiuser detection (MUD) receivers can provide better interference rejection than the conventional detector used in 2G system (like IS-95). The optimal MUD detector which is the maximum likelihood detector is too complex for practical implementation with today's technology. Due to this complexity, most of researches have focused on finding suboptimal low complexity multiuser detectors solutions that are feasible to implement. In this thesis, we investigate the performance of a new receiver structure which uses decision feedback equalizer (DFE) as a multiuser detector. A modified DFE structure in which error feedback filter (EFF) is added to the main structure is also investigated. The performance of these proposed structures will be compared to the decorrelator detector (DD). The proposed structure is shown to exhibit good MAI rejection as well as near far resistance.