Performance of spectrum-sharing constrained two-way relaying

This paper investigates the performance of a two-way cognitive relaying network in Rayleigh fading environment. We consider that two secondary users (SUs) are allowed to access a licensed portion of the frequency spectrum and share it with a primary user (PU) provided that their transmission power meet interference constraints dictated by the primary receiver. Considering that the SUs are unable to directly communicate with each other, a set of L terminals intervene to relay the information between the source nodes. For efficiency regarding the utilization of the licensed spectrum, only the “best” relay is selected, by means of opportunistic selection, to process and relay the received signals. We derive closed-form expression for the probability density function (PDF) of the signal-to-noise ratio (SNR) of each of the links between the “best” relay and the source nodes, followed by the average bit error rate (ABER), the outage probability and the ergodic capacity. We also provide numerical results to assess the theoretical analysis.