Generalized Performance Analysis of Adaptive PSAM-Based Transmit-Beamforming for Wireless MIMO systems

The impact of imperfect channel state information (CSI) on the performance of transmit-beamforming (TB) over multiple-input multiple-output (MIMO) Rayleigh fading channels when using constant-power rate-adaptive pilot-symbol-assisted modulation (PSAM), is investigated. Specifically, imperfect CSI is accounted for with respect to both estimation and prediction errors. Such errors entail a mismatch between the optimal transmit and receive beamforming weight vectors and the constellation size for adaptive modulation as implied by the true CSI and the actual values of these parameters as determined according to the predicted CSI, thereby degrading the performance of the adaptive PSAM-based TB system. The compound effect of both estimation and prediction errors on the overall system performance is assessed in terms of the achievable average spectral efficiency, average bit error probability and outage probability, for which approximate closed-form expressions are derived for arbitrary numbers of transmit and receive antennas