Robustness evaluation of uniform power allocation with antenna selection for spatial Tomlinson-Harashima precoding

The performance of any communications precoding scheme relies on the quality of the channel state information that is made available at the transmitter side. In this paper, we study the robustness of spatial Tomlinson-Harashima precoding (STHP) in terms of rate loss when errors are considered in the feedback link. We will evaluate the performance degradation of the uniform power allocation with antenna selection strategy for STHP (which is quasioptimal when there are no feedback errors) and compare it with a robust power allocation designed to maximize the achievable rates for the worst-case feedback noise. It is shown that the performance difference between both approaches is very small. Consequently, uniform power allocation with antenna selection arises as a good solution for STHP even in the presence of feedback errors.