Space-Time Multi-User Detection For CDMA System

MAI (Multiple Access Interference) is the primary interference of CDMA system, which can lead to "near-far effect" and limit the capacity of the system, so the study of anti-MAI technique has great significance. Multi-User Detection (MUD) technique is the most effective anti-MAI technique in CDMA system. It is a method of anti-interference based on the receiver's design. While space-time processing reduces the interference in virtue of the special property of the signal obtained from the antenna array. Combining the two techniques into space-time MUD (ST-MUD) is heatedly discussed in recent studies.Sub-optimum ST-MUD is widely studied because optimum ST-MUD's computational complexity increases in exponent with the increase of users' number. In this paper the decorrelating ST-MUD technique is studied, based on which a de-biasing decorrelating ST-MUD is proposed. The de-biasing decorrelating ST-MUD's computational complexity is relatively small, and its performances are superior to the ordinary decorrelating ST-MUD. It is suitable for the situation of base station receiving. In this paper the blind ST-MUD based on GSC algorithm is also studied which is suitable for the situation of mobile phone's receiving .