Performance Analysis of Relay Site Planning over Composite Fading/Shadowing Channels with Co-channel Interference

The performance of relay deployments depends significantly on the capacity of the wireless relay link between a relay node (RN) and its serving base station (BS). Exploiting the deployment flexibility of RNs, relay site planning (RSP) can be utilized to overcome the limitations of the relay link. In particular, RSP is carried out by selecting RN deployment locations from a discrete set of alternatives considering the signal-to-interference-plus-noise ratio (SINR) on the relay link as the selection criterion. In this work, we present an analytical framework for RSP that can be used for planning and dimensioning of two-hop cellular relay networks operating over composite fading/shadowing channels in the presence of co-channel interference. Nakagami-lognormal distribution is used to model the relay link while the access link between a mobile terminal (MT) and its serving RN is modeled by Rician-lognormal distribution. As these composite models do not have closed-form distribution functions, we utilize mixture gamma (MG) distribution to accurately approximate them. Further, the total co-channel interference in the considered multi-cellular system is approximated using moment generating function (MGF)-matching method. Accordingly, we present closed-form expressions for the distributions of relay link SINR, link rates and end-to-end rate. Besides, RSP is shown to effectively decrease the amount of fading (AoF), and thus mitigate the detrimental effects of composite fading/shadowing. Thorough results reveal significant performance improvements which justify the use of RSP in cellular relay networks.?