Sphere Decoding for Space-time Multiuser Detection in STBC-DS-CDMA System

Abstract

In this paper, a new uplink DS-CDMA system based on Alamouti STBC is proposed in order to restrain the multiple access interference (MAI) in DS-CDMA system. In the new system, data is modulated by BPSK and encoded by sing Alamouti space time block codes before transmitting. And we apply sphere decoding algorithm in the space-time multiuser detection process. The equivalent MIMO structure of received signals is also analyzed. Simulation result shows superiority of combining the new uplink system with space-time multiuser detection using sphere decoding.