A transmitter design for coded systems in the presence of CSI errors

Linear transmitter designs that optimally allocate the power using partial CSI at the transmitter have been recently studied under optimization criteria based on MMSE and minimum uncoded BER. Unfortunately these criteria do not guarantee good performance when error correction codes are introduced. In this paper we introduce a design on the transmitter, robust to CSI errors, based on the channel cut-off rate Ro. This parameter provides a lower bound on the capacity, and has been considered for a long time as the practical bound on the performance that could be achieved by feasible channel codes. The use of Ro allows optimizing coded BER performance while keeping the design independent of the specific channel code used in the system. Simulation results in the paper will show the improved performance of this scheme compared to robust MMSE, minimum uncoded BER and open-loop schemes.