Multiuser Diversity in Network-Coded Cooperation: Outage and Diversity Analysis

In this letter, we study multiuser diversity (MUD) in network-coded cooperation (NCC) systems. Specifically, we propose a two-step user-relay selection mechanism that selects subsets of users and relays to exploit both MUD and cooperative diversity in a multiuser multirelay NCC system. Assuming independent but not necessarily identically distributed Rayleigh fading channels, we derive closed-form expressions for the system outage probability. We further obtain asymptotic outage expressions to quantify the diversity order as a function of different system parameters. Our results demonstrate the superiority (diversity gains) of the proposed MUD-based NCC compared with NCC schemes without MUD. Monte-Carlo simulations are also presented to verify the accuracy of our theoretical findings.