CMMSE reception for MIMO DS/CDMA systems employing space-time block-codes and spatial multiplexing

Abstract

In this thesis, interference suppression schemes for the space-time block-coded (STBC) CDMA systems, spatially multiplexing systems and layered STBC systems in the frequency selective fading channels are considered. For the STBC multiple-input multiple-output (MIMO) CDMA systems, an adaptive interference suppression scheme is developed. It is shown that the complexity of the proposed CMMSE receiver is almost independent of the number of transmitter antennas. Analytical and simulation results demonstrated that the proposed receiver can provide a considerable convergence and detection performance improvement over the existing adaptive interference suppression schemes for the STBC CDMA and the gain achieved by suppressing the MAI can be larger than that from increasing the receiver diversity. The proposed adaptive CMMSE receiver can be applied to both up- and downlink communications operating in either a circuit or a packet mode. For the spatial multiplexing based MIMO CDMA systems, a multiple scrambling code aided spatial multiplexing method for the CDMA systems is proposed. Conventional V-BLAST based spatial multiplexing system showed severe perfor-mance degradation in the spatially correlated channels and the number of receiver antennas should be at least the number of transmitter antennas to classify data streams using different spatial signature. In the proposed method, by assigning different scrambling code for each transmitter antenna, all simultaneously transmitted streams can have different signature sequences and they can be classified at the receiver using the conventional interference suppression schemes for single-input single-output (SISO) CDMA. Computer simulation results indicate that the proposed transceiver shows stably acceptable detection performance regard-less of the channel correlation and the receiver does not need to have multiple antennas. Finally, two types of layered STBC MIMO transceivers for DS/CDMA systems in frequency selective fadi...