Secure Cooperative Single Carrier Systems under Unreliable Backhaul and Dense Networks Impact

In this paper, the impacts of unreliable backhaul links on the secrecy performance of cooperative single carrier heterogeneous networks in the presence of eavesdroppers are investigated. A two-phase transmitter/relay selection scheme is proposed, where the best transmitter is selected to maximize signal-to-noise ratio at the relays in the first phase and the best relay is chosen in the second phase to minimize the signal-to-interference-plus-noise ratio of the eavesdroppers with the aid of a friendly jammer. Closed-form expressions are derived for the secrecy outage probability, probability of non-zero achievable secrecy rate, and ergodic secrecy rate. The asymptotic performance analysis is furthermore performed to explicitly reveal the impacts of unreliable backhaul links on the secrecy performance. Our results show that the diversity gain cannot be achieved in the presence of imperfect backhaul links.