Accurate SER expressions for M-ary dual ring star QAM in fading channels

Analytical expressions for symbol error rate (SER) of M-ary dual ring star shaped quadrature amplitude modulation (QAM), when corrupted by additive white Gaussian noise (AWGN), have been derived. Utilizing the result for AWGN channel, SER expressions for various frequency non-selective slow fading channels (e.g. Rayleigh, Rician, and Nakagami-m) are also found. The results obtained are in the form of summation of single integrals which can be easily calculated through numerical methods. More importantly, compared to the erroneous results published earlier, the derived expressions are accurate. Extensive Monte Carlo simulations were performed to validate the analytical framework. The inadequacy of Gray's approximation for calculation of bit error rate (BER) has also been pointed out.