Impact of imperfect channel knowledge on transmit processing concepts

Common transmit processing concepts are either based on complete, partial, or no channel state information (CSI). But the quality of CSI is crucial for a fair comparison. Therefore, we derive an explicit expression of the bit error probability (binary modulation) for the transmit matched filter, beamforming, and Alamouti space-time block code in case of linear estimation and prediction of the channel coefficients or a delay of the channel estimates. Uncorrelated as well as correlated frequency flat channels are considered. Based on the analytical expressions a comparison for these three representatives for all three types of CSI is made. The break even point between the three schemes is computed numerically, which can serve as a switching point between the concepts.