Dual-hop cooperative spectrum sharing systems with multi-primary users and multi-secondary destinations over Nakagami-m fading

This paper investigates the outage performance of dual-hop decode-and-forward (DF) cooperative spectrum sharing systems in the presence of multiple primary user (PU) receivers and multiple secondary user (SU) destinations. Our analysis allows for a general Nakagami-m fading environment where distinct fading parameters as well as unequal average fading powers between the interference and relaying links are assumed. Focusing on the cooperation process among the SU nodes and making use of the underlay cognitive approach, an exact closed-form expression for the outage probability is derived. Our analysis employs an opportunistic scheduling algorithm for selecting one out of L SU destinations available. Additional interference constraints are also considered due to the presence of multiple PU receivers. The effects of fading severity, SU relay placement, and number of PU receivers, and SU destinations on the end-to-end system performance are examined through some representative numerical plots. Monte Carlo simulation results are presented to corroborate the proposed analysis.