Performance Analysis of Non-Uniform Modulations over AWGN and Rayleigh Fading Channels

This article presents an analysis of the performance of Non-Uniform Constellations, also known as Ultra-Multilevel, corresponding to the Digital Modulation of Quadrature Amplitude (QAM), obtained through the optimization of conventional M-QAM Constellations of order M = 16, 64, 256 1024 and 4096, from the Bit-Interleaved Coded Modulation (BICM). To estimate the behavior of a modulated bit stream with these Constellations, two metrics were used: the Signal to Noise ratio (SNR), and the Probability of bit error. Two possible scenarios for a Communications Channel were considered. The first case corresponds to a Channel with Gaussian White Additive Noise (AWGN), and the second case to an AWGN Channel that has been affected by Fading. Channel simulation was performed based on the statistical models of probability distribution, Gaussian and Rayleigh. The results for each case were obtained with the Monte Carlo method. The performance results of the Conventional QAM Constellations with the results of the Non-Uniform QAM Constellations were compared, and it is determined which of them behave optimally with each value of a wide range of SNR values.