Outage and ergodic capacity expressions for fixed-gain relay networks in the presence of interference

In this paper, we analyze the outage and ergodic capacities of a dual-hop cooperative system equipped with a single fixed-gain (also known as semi-blind) relay whilst considering an interference at the relay terminal. We derive the expression for end-to-end signal-to-interference and noise ratio (SINR) of the system under consideration. Using this expression, we then derive new exact closed-form expressions for the outage and ergodic capacities assuming flat Rayleigh fading conditions. Furthermore, new analytical closed-form expressions are derived for the gain of relay which are then used in the numerical simulations. Finally, we also provide the Monte Carlo simulations and show their exact match with our derived closed-form expressions.