Cognitive two-way relay systems with multiple primary receivers: Exact and asymptotic outage formulation

This study is concerned with outage performance analysis of a cognitive two-way relay system having a primary network of one transmitter and multiple receivers over Nakagami-m fading channels. In the considered cognitive radio system, the secondary network facilitates information exchange between source nodes with the aid of multiple decode-and-forward two-way relays. In the presence of multiple relays, opportunistic relay selection is employed to obtain a relay with the best channel quality for reliable information recovery. To analyse the performance of the considered cognitive radio system, exact and asymptotic closed-form expressions of outage probability (OP) are derived in this study. The derived theoretical OP expressions are in good agreement with related empirical values which show that using relays can enhance the performance of secondary networks without sacrificing that of the primary network. © The Institution of Engineering and Technology.