Outage Performance and Diversity Analysis for Multiuser Multi-relay Cognitive Radio Systems

In this paper, considering a multiuser multi-relay spectrum sharing cognitive radio system, the exact outage probability and diversity order for such a system are derived over Rayleigh fading channels. The theoretical analyses are validated by simulations. Both theoretical analyses and simulations show that the derived exact outage probability is accurate, and the diversity order is (M+1)N (where M is the number of relays and N is the number of users) for the selection decode-and-forward (SDF) protocol. It is indicated that both multi user selection diversity and multi-relay selection cooperative diversity can be achieved simultaneously for SDF protocol in spectrum sharing cognitive radio systems.