Eigen-selection approach for joint beamforming and space-frequency coding in MIMO-OFDM systems with spatial correlation feedback

This paper addresses the problem of joint optimization of transmit beamforming and space-frequency (SF) coding for MIMO-OFDM systems with spatial correlation feedback. This problem is challenging in the sense that the transmitter should be designed to beamform across multiple eigenspaces. The performance analysis for SF-coded MIMO-OFDM systems with beamforming is provided, and a general optimization problem for the beamforming design is formulated. Three suboptimal approaches to design the beamformer based on the derived design criteria are proposed. In terms of bit error rate, simulations show that improvement in the performance over SF coding without beamforming is about 3 dB for highly correlated channels.