Secure 5G Coordinating Spectrum Sharing System With Cooperation Transmitter and Receiver Pairs

ABSTRACT In this paper, we propose a 6‐node system consisting of two transmitter‐receiver pairs sharing the same spectrum, an eavesdropper, and a relay, all operating in a half‐duplex. The eavesdropper is mainly interested in communication between one of the transmitter‐receiver pairs, which we call the primary. Communication along with the second pair called the secondary, is performed in two hops/time slots with the aid of the relay. The main idea of our study is to investigate the secrecy performance of the primary pair when jamming is performed by the secondary relay‐assisted path. In particular, in the first time slot, the secondary destination acts as a jammer relative to the eavesdropper by injecting artificial noise known to the primary pair. During the second time slot, the secondary transmitter acts as a jammer while the relay forwards data to the secondary destination. In effect, this allows for cooperation among the nodes both in transmitting primary and secondary data while reducing the eavesdropper's ability to listen in on the primary link communication. For the proposed protocol, we derive closed‐form expressions of the intercept probability. We also obtain a closed‐form expression of the outage probability along with the secondary communication link. Moreover, we study the effect of transmit power allocation on intercept and outage probabilities along with the different links. Theoretical and simulation results are given to prove that the proposed protocol can provide better security for the primary link and acquire acceptable secondary outage probability.