Performance analysis of multiuser uplink amplify-and-forward relay networks with fixed-gain relaying

In this paper, a multiuser uplink amplify-and-forward (AF) relay system with a multiple-antenna destination is considered where fixed-gain relaying and opportunistic scheduling are employed. Closed-form expressions for outage probability and average symbol error rate (SER) in Rayleigh fading environments are derived. Also, asymptotic expressions for outage probability and average SER are presented. The coding gain and diversity order are obtained. The analysis demonstrates that the total diversity order of the system equals min{K, M} where K is the multiuser diversity order and M is the spatial diversity order. Finally, comparisons between multiuser relaying systems and multiuser point-to-point systems are made and some insights are provided.