Joint Space-Time Transmitter-Receiver Beamforming

Joint transmitter-receiver beamforming is a powerful approach that has been considered for the downlink DS-CDMA system over frequency-selective channels and much recent effort is devoted to its integration with spatio-temporal (ST) processing. In the DS-CDMA system, the ST processing has been employed at the receiver, however, with the transmitter based on spatial-only processing (S-ST). In this paper antenna arrays with ST integration are employed at both transmitter and receiver (ST-ST) aiming at further improving the performance over S-ST in frequency-selective channels. The joint optimization problem is solved by an iterative method and a closed-form method respectively. The mean square error (MSE) of ST-ST and S-ST is derived using the closed-form solution which can be considered as an upper bound when the system is lightly loaded.