On the Sum and the Maximum of Nonidentically Distributed Composite $\eta{-}\mu/\text{gamma}$ Variates Using a Mixture Gamma Distribution With Applications to Diversity Receivers

In this paper, the statistical characterizations of the sum and the maximum of independent and nonidentically distributed (i.n.d.) composite η-μ/gamma variates are derived using a mixture gamma (MG) distribution. The statistical properties, namely, probability density function (pdf), cumulative distribution function (cdf), and moment generating function (MGF) are obtained in general unified exact analytic expressions. These statistical results are then used to analyze outage probability (OP), average bit error rate probability (ABEP), and average channel capacity (C) of maximal ratio combining (MRC) and selection combining (SC) schemes over i.n.d. composite η-μ/gamma fading channels. The validation of our derived expressions is verified by comparing the numerical and simulation results.