Security-and-Reliability Trade-off of Energy Harvesting-Based Underlay Relaying Networks with Transmit Antenna Selection and Jamming

We propose a system model for energy harvesting-based underlay relaying networks with transmit antenna selection and jamming where a multi-antenna unlicensed relay performs multiple tasks [received signal combining, transmit antenna selection (TAS), energy harvesting] to save energy consumption, ensure continuous connection of an unlicensed source to an unlicensed destination, and secure transmission against a wire-tapper. Moreover, to guarantee security for source-to-relay transmission, we propose embedding jamming signal into secret information at the source to reduce the wire-tapper’s capability of decoding source message. To swiftly illustrate security-and-reliability trade-off of the proposed system model as well as compare with its counterparts so as to highlight our contributions, we propose closed forms of intercept and outage probabilities at the wire-tapper and the destination, correspondingly, under licensed interference and restraints of peak transmit/interference powers. We found from various results that (1) the proposed TAS scheme achieved the best reliability-and-security trade-off in comparison with previous schemes; (2) reliability saturation occurs at high peak transmit/interference power; (3) licensed interference and time for energy harvesting drastically enhance security yet mitigate reliability; (4) distributing power properly to secret and jamming signals at the source brings better security; (5) increasing the number of antennas at the relay dramatically improves both security and reliability for the proposed TAS scheme.