On the Performance of Adaptive SC/MRC Cooperative Systems over Composite Fading Channels ∗

We investigated a simple Adaptive selection/maximal-ratio (ASM) combining cooperative system with output threshold over independent non- identical composite Nakagami-lognormal fading channels using Mixture gamma (MG) distribution. Some novel closed-form expressions for the probability density func- tion, the cumulative distribution function and the moment- generation function of the output Signal-to-noise ratio (SNR) for the ASM system are derived, respectively. The average symbol error rate, outage probability and the di- versity order for the ASM system are given based on the above expressions. For the purpose of comparison, we also derive the statistical characterizations of the conventional selection combining and maximal-ratio combining cooper- ative systems using MG distribution. Numerical and sim- ulation results are shown to verify the accuracy of the an- alytical results under different scenarios, such as varying average SNR, fading parameters per hop, and the location of relaying nodes. These results show that ASM is a sim- ple and flexible cooperative system, and can be useful in future practical deployment.