Performance of coherent square M-QAM with Lth order diversity in Nakagami-m fading environment

The symbol error rate (SER) performance of coherent square M-ary quadrature amplitude modulation (M-QAM) with L^th order diversity frequency non-selective slowly Nakagami-m (1960) fading environment corrupted by additive white Gaussian noise (AWGN) is presented. The diversity combining technique considered in this paper is maximal ratio combining (MRC) with identical channels. The derived expression for SER is in terms of a single finite integral with an integrand composed of elementary (trigonometric) functions. Because of its simple form, the expression readily allows numerical evaluation for cases of practical interests. The solution presented in this paper is general enough so that it includes half Gaussian fading (m=0.5), Rayleigh fading (m=1), and nonfading (m=∞) as special cases. The results are plotted as SER versus signal to noise ratio (SNR) for various values of m and L to examine the dependence of the performance of MQAM on m and L. The results presented are expected to provide useful information needed for exploiting the use of diversity for design of better communication systems in Nakagami-m fading environment