Robust power allocation algorithms for MIMO OFDM systems with imperfect CSI

Abstract—This paper presents a Bayesian approach to the de-sign of transmit prefiltering matrices in closed-loop schemes ro-bust to channel estimation errors. The algorithms are derived for a multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) system. Two different optimization criteria are analyzed: the minimization of the mean square error and the minimization of the bit error rate. In both cases, the trans-mitter design is based on the singular value decomposition (SVD) of the conditional mean of the channel response, given the channel estimate. The performance of the proposed algorithms is analyzed, and their relationship with existing algorithms is indicated. As with other previously proposed solutions, the minimum bit error rate al-gorithm converges to the open-loop transmission scheme for very poor CSI estimates. Index Terms—Channel state information, diversity, fading channels, feedback, joint transceiver optimization, linear pre-coding, MIMO channels, OFDM, power allocations, wireless communications. I