Frequency-Domain Pre-Equalization for Single-Carrier Space-Division Multiple-Access Downlink Transmissions

A frequency-domain pre-equalization scheme for single-carrier space-division multiple-access (SC-SDMA) downlink transmissions is proposed in this work. In the system of our interest, both the base station (BS) and mobile terminals (MTs) are equipped with multiple antennas. It operates in a time-division-duplex (TDD) mode and the channel reciprocity between alternative uplink and downlink transmissions is exploited to feed the channel state information (CSI) back to the transmit side. Pre-filtering coefficients are designed so as to minimize the sum of mean-squared-errors at all MTs under an overall transmit power constraint. Several strategies are investigated for linearly combining the received signals at each MT in the frequency domain. Simulation results are provided to demonstrate the effectiveness of the proposed scheme