Impact of imperfect CSI estimation on multidimensional communication systems over a Rayleigh fading channel

A general multidimensional communication system, with a background of DS/SS, is proposed, where a set of orthogonal functions is used to form the signal space and a maximum likelihood (ML) detector is used in the receiver. The error rate is evaluated for both non-fading and Rayleigh fading channels under the conditions of imperfect channel state information (CSI). Numerical results are provided to show the effect in the CSI estimation on the error rates of the systems, and some general conclusions are presented based on these results. In general, we find that errors of the CSI estimation can seriously degrade the system performance, especially under good channel conditions (such as non-fading conditions).