Finite Blocklength Non-Orthogonal Cooperative Communication Relying on SWIPT-Enabled Energy Harvesting Relays

A finite blocklength (FBL) twin-user non-orthogonal cooperative downlink system is considered, wherein a base station simultaneously communicates with the users whilst relying on simultaneous wireless information and power transfer (SWIPT) enabled energy harvesting relay. Closed-form analytical expressions are obtained for the end-to-end average block error rate (BLER) assuming potentially dissimilar Nakagami-m fading links. Furthermore, asymptotic expressions are derived for the individual user's end-to-end average BLER performance and diversity order at high signal to noise ratios (SNRs). Additionally, since, the stronger user's signal is detected, while assuming the weaker user's signal to be interference, an analytical bound has been obtained for characterizing the effect of this interference on the BLER performance of both users. Furthermore, a framework is developed for joint relay splitting factor and user power allocation towards end-to-end blocklength minimization under strict reliability constraints by converting the original non-convex optimization problem to a convex geometric program (GP) that can be solved efficiently. Simulation results are presented to validate the analytical expressions derived and illustrate the efficacy of the proposed scheme.