Outage Probability of Spatially Diverse Multi-Source Multi-Relay Multi-User Two-hop Relay Networks

This work presents a novel framework for analyzing the outage performance of the amplify-and-forward (AF) protocol-based spatially diverse multi-source multi-relay multi-user two-hop cooperative relay networks (TCRNs) with potential applications in characterizing unmanned aerial vehicle (UAV) and maritime TCRNs. We consider spatially distributed MIMO communications between arbitrary shaped spatial regions populated with randomly distributed sources, i.e., base stations (BSs), and users, i.e., mobile stations (MSs). It is assumed that the cooperative BSs in the BS region broadcast signals to the MSs in the MS region through multiple relay stations (RSs) that are located randomly within the RS region. We utilize the properties of Hilbert space to analyse such systems and provide a contemporary perspective on the transmit diversity and spatial multiplexing transmission techniques. We then propose relay-selection criteria to choose the best relay which maximizes the system signal-to-noise ratio (SNR) and derive asymptotic closed-form expressions of the outage probability in Rayleigh fading. Both the theoretical predictions and numerical modeling clearly indicate that the outage probabilities of the proposed TCRNs are limited by the sizes of the spatial regions and by exploiting spatial diversity, a significant gain in system's SNR is attainable for both transmission techniques.