Outage probability of finite-sized selective relaying systems with unreliable backhauls

Considering unreliable wireless backhaul connections across transmitters, we investigate the outage performance of a finite-sized selective relaying system with M transmitters and N relays under Nakagami-m fading channels. To send the source message to the destination, the transmitter-relay pair providing the highest end-to-end signal-to-noise ratio is selected for transmission. The backhaul reliability is introduced to reflect the practical constraints on transmitter-relay cooperation. The closed-form outage probability and asymptotic outage performance limits are derived for the finite-sized selective relaying system. It is shown that asymptotic outage probability is exclusively determined by M and a set of backhaul reliability levels. It is also shown that diversity gain promised by the finite-sized selective relaying system is determined by M, N, and shape factors of Nakagami-m fading channels. Link-level simulations are conducted to verify the derived joint impact of backhaul reliability and transmitter-relay cooperation on the outage performance.