Abstract:Multiuser Detection (MUD) is a key technique in DS/CDMA systems. Antenna array has also promoted the investigation of Multiple Input Multiple Output(MIMO) system. In this paper a MUD method combined with MIMO considerations is proposed for multiuser interference reduction in antenna array DS/CDMA system. The knowledge that the base station knows many users spreading codes is utilized to form a semiblind MUD algorithm. This algorithm can work under slow fading environment, and simulation proves the superiority of the semiblind algorithm over the conventional blind algorithm.