Impact of imperfect channel estimation on turbo multiuser detection in DS-CDMA systems

In practical wireless communications, channel estimation is imperfect due to the effects of noise and interference. This paper analyzes the impact of imperfect channel estimation on a form of turbo multiuser detection based on linear minimum-mean-square-error (MMSE) detection and parallel interference cancellation. In particular, the variance of the noise caused by the channel estimation error is analyzed for full and reduced rank MMSE detectors and parallel interference cancellation in the large system limit.