Precoder Design for MIMO Systems with Transmit Antenna Correlations

This paper studies precoding strategies applicable to MIMO systems with transmit correlations, for the case of frequency division duplex (FDD). Earlier work has enabled the downlink channel covariance matrix (DCCM) to be estimated easily from the uplink channel covariance matrix (UCCM), which can be estimated from uplink channel measurements. Thus, feedback of the correlation information from the mobile stations to the base station is not required. We first propose a scheme that uses the estimated DCCM to perform both the power allocation and eigen-beamforming. We then develop a hybrid scheme that uses both the UCCM and the estimated DCCM to perform power-allocation and eigen-beamforming, respectively. Computer simulations are presented to compare the throughput performance of the hybrid scheme with methods solely based on UCCM or estimated DCCM