Improving robustness of precoded MIMO systems with imperfect channel estimation

Low-rate feedback schemes have recently provided a means to achieve near optimal performance in multiple-input multiple-output communications systems while reducing feedback overhead to acceptable levels. In this paper, a bit-error rate expression for precoded systems is derived as a function of the channel estimation uncertainty. Poor channel state estimates are shown to degrade error rate performance significantly; however, if the channel estimation uncertainty is taken into account when selecting feedback parameters, it is shown that target performance can be maintained without wasting resources.