Performance analysis of LMMSE receivers for M-ary QAM in Rayleigh faded CDMA channels

Abstract

In this paper, we develop approximations for the symbol error rate in a wireless code-division multiple-access channel. We assume that each user employs spectrally efficient M-ary quadrature amplitude modulation and undergoes independent Rayleigh fading. We study the performance of linear minimum mean-squared error receivers in situations where: i) the channels of all users are known perfectly; ii) the receiver knows only the average powers of the interferers but the channel of the user of interest is still assumed to be perfectly known; and iii) the channels of the interferers are unknown and there is estimation error in the channel estimate of the user of interest. In the last of these cas..