Multi-cell Interference in Multi-Relay Networks with Nakagami-m Fading Channels

In this paper, three relay selection protocols for multi-cell networks with multiple decode-and-forward relays targeted by multiple interferers at the relay and the destination are proposed and analyzed. The following three protocols are considered: 1) opportunistic best-worst (OBW) where the destination selects the best signal between the direct and the relayed transmissions, 2) best-worst direct link combiner (BWDC) where the destination combines the direct and the relayed transmissions using maximum ratio combining, and 3) hybrid opportunistic best-worst (HOBW) where the destination only selects the relayed transmission when the direct transmission is in outage. For each of these, new closed-form expressions for the outage probability over independent non-identically distributed (i.n.i.d.) Nakagami-m fading channels are derived. New design insights into the outage probability in the high interference regime are obtained. Compared to BWDC, OBW and HOBW offer a lower complexity receiver. Further, we show that OBW and HOBW achieve a lower outage probability relative to BWDC in the high interference regime.