Achievable Error Rate Reduction with Hexagonal QAM Constellations Over the Shadowed Fading Channels

The proposed research performs a comparative analysis of the average error rate for a wireless communication system with a shadowed fading channel with M-QAM with various shapes of the signal constellation: square (SQAM), regular (RHQAM) and irregular hexagonal (IHQAM), carried out for a recently published model - the fluctuating Nakagami-m channel. Numerical simulation has shown that an appropriate shape of the signal constellation can reduce the error rate significantly. Under the conditions of signal propagation corresponding to this channel model, the worst form of the constellation for almost all values of the channel model parameters and the signal-to-noise ratio is RHQAM, and the greatest reduction is provided by the choice of IHQAM (upto about 20%). The influence of the model parameters on the value of the achievable gain is investigated. Scenarios in which system performance is insensitive to the channel model parameters or to the signal-to noise ratio have been found.