Tradeoff between diversity gain and interference suppression in a MIMO MC-CDMA system

In this paper, the uplink of an asynchronous multi-carrier direct-sequence code-division multiple-access (MC-DS-CDMA) system with multiple antennas at both the transmitter and the receiver is considered. We analyze the system performance over a spatially correlated Rayleigh fading channel with multiple-access interference (MAI), and evaluate the antenna array performance with joint fading reduction and MAI suppression. Assuming perfect channel knowledge available at the transmitter, maximal ratio transmission is employed to weight the transmitted signal optimally in terms of combating signal fading. At the receiver, adaptive beamforming reception is adopted to both suppress MAI and combat the fading. Note that while correlations among the fades of the antennas in the receive array reduce the diversity gain against fading, the array still has the capability for interference suppression. We examine the effect of varying the number of transmit and receive antennas on both the diversity gain and the interference suppression.