Conceptual Question on equalization technique in rayleigh fading channel based on a paper
The model they have used is general and you can apply it to QAM as well.
In wireless communication systems, channel and noise are two different impairments affecting the overall transmission. Here as everywhere else, the noise is AWGN (additive white Gaussian; if you want to know what these terms mean, see this article). And the channel is a linear filter with taps whose magnitudes are modeled as Rayleigh random variables.
Yes, you can use the expression in that paper. The authors didn't give the expression because they might not have known it and simply generated it from Monte Carlo simulations.