BER for M-QAM with Space Diversity and MRC in Rician Fading Channels

This paper presents simple bit error rate results for M-ary quadrature amplitude modulation (M-QAM) transmitted over slow, flat, identically independently distributed (i.i.d) Rician fading channels and using space diversity to enhance coverage and capacity. A single exponential function is used to approximate the bit error rates (BER) for M-QAM modulation over a Gaussian channel. This approximation is bounded within 1 dB for the signal alphabet M ges 4 and 0 les SNR les 30 dB. BER for optimum, maximal-ratio-combining (MRC) receive diversity, with channel side information known at the receiver (CSIR) is then obtained. Recently exact analysis of symbol error rate (SER) has been presented in the literature for M-ary differentially encoded/ differentially decoded phase shift keying (MDPSK) and coherent M-ary phase shift keying (MPSK), and for M-QAM transmitted over Rician fading channel using N branch receive MRC diversity. The results are presented either in an integral form or in the form of hyper-geometric infinite series. Unfortunately its use leads to numerical un-stability. Our analysis has followed the same track and the simplicity of the SER expressions used has resulted in simple closed form expression of the SER of N order diversity at Rician fading channel. Our expressions contain only exponential functions.