BLIND DETECTION FOR MULTI-RATE DS-CDMA SYSTEM WITH ANTENNA ARRAY AT THE BASE STATION

In this paper, we propose the blind space-time high rate multi-user detector for synchronous uplink multi-rate Direct Sequence Code Division Multiple Access (DS-CDMA) systems with antenna array at the base station. By employing antenna array at the base stations, the spatial dimension is used efficiently to sup-press co-channel interference and increase the capacity for multi-rate CDMA system. After low rate physical users in the system are modeled as corresponding high rate virtual users, we construct the space-time signature vectors of virtual users. And subspace projection algorithm is employed to estimate space-time signature vec-tors blindly. Then a soft-decision high rate multiuser detector is proposed based on the estimated signature vectors, which avoids estimating the ambiguous complex factors which are necessary in traditional blind de-tector. Numerical simulation results evaluate the performance in terms of Bit Error Rate (BER) for the pro-posed scheme. Simultaneously, it demonstrates that the system capability increases two times when using two- element antenna array.