Energy Efficiency in Secrecy Multi-Antenna Two-Way Relay Networks

paper investigates the energy-efficiency in secrecy two-way relay networks. It is assumed that in the presence of several multi-antenna amplify-and-forward relays and a single eavesdropper, two single-antenna users exchange their confidential messages during two hops. In the first hop, both users send their messages to the relay nodes and during the second hop, the relays send the received signal to the users by using the beamforming matrix, to minimize the received information by the eavesdropper .In this way, using two beamforming strategies, named as Null-Space Beamforming (NSBF) and Information Leakage Alignment Beamforming (ILABF), the secrecy energy efficiency that is the ratio of total secrecy sum-rate to the total power consumption of the network is calculated. It is shown that the aforementioned problem is non-convex so it will be converted to the convex form, using the Semi-Definite Relaxation (SDR). This problem has not closed-form and is solved using the interior point method.In numerical results, it is observed that by using the information leakage alignment beamforming (ILABF) method, energy efficiency is allocated more value than the null-space beamforming (NSBF) approach that was used in previous studies.