Sequential detection CDMA multi-user receiver

Abstract

SUMMARYThis paper proposes a sequential detection technique for a multi-user receiver that is constructed over a CDMA system. In this system, the transmitter transmits a symbol made by spreading the spectrum with an enveloped sequence protected by guard sequences, and a receiver de-modulates the core-sequence part of the received symbol with either a de-correlating detector or an MMSE detector. The advantage is that performance is improved without reducing the number of the active users. This sequential detection system estimates the best user signal from all of the soft outputs, which are obtained by solving a de-correlating system of equations. Once detected, the best user component is removed from the received symbol. The resultant symbol composed of the remaining user signals is then sequentially detected by repeating the method stated above. A computer simulation of this system reveals a remarkable improvement in the biterror rate performance compared to conventional systems.

A multi-rate CDMA system with block-spreading schemes for anti-interference and high frequency efficiency

“…(20). A single rate (spreading factor Ä) conventional CDMA system might also achieve the full capacity, if a de-correlating detector is used to separate ô ĵ user symbols[10] [11]. However such detector can not be applied to an OVSF system using symbols composed of rate dependent length.…”