Cognitive Relay Sharing for Two-Way Primary Transmissions Under Nakagami-m Fading Channels

In this paper, we investigate the outage performance of a cognitive relay sharing system (CRSS) with two-way primary communications using an amplify-and-forward (AF) based multiple access broadcast (MABC) protocol. Herein, besides cooperating the secondary users' transmissions, the relay aids in carrying out the two-way transmissions of primary users. Moreover, the secondary system employs an opportunistic user scheduling with multiple destinations for ameliorating the secondary network's performance. Considering Nakagami-m fading channels, we derive novel closed-form expressions of outage probability for both primary and secondary systems. With two-way primary communications, the proposed CRSS will offer higher spectral efficiency and incentivize the secondary communication through multiuser diversity. Numerical and simulation results are obtained for the veracity of our theoretical developments.