Effect of imperfect channel estimation on synchronous multi-rate DS/CDMA systems with high spreading factors

This paper analyzes the influence of channel estimation errors on the performance of linear multi-user receivers. Assuming randomized codes and asymptotically high spreading factors and noise power, we show that the performance of the decorrelating and the minimum mean squared error (MMSE) receivers tend to the same limit in terms of signal to noise ratio and bit error rate (but not in terms of mean squared error). Using these results and assuming Gaussian-distributed channel estimators, we derive two simple approximations to the bit error rate and compare them with the actual values via simulation.