Secrecy Performance of Energy Harvesting Based D2D Communications in Spectrum-Sharing Networks

This work considers a secure cognitive device-to-device (D2D) communications network, where the D2D source (S) transmits the secret information to the D2D destination (D) through energy-constrained D2D relay (R) using the spectrum of the primary base station (BS) under the malicious attempt of D2D eavesdropper (E). We propose secure time switching-based relaying (TSR) in a D2D wireless-powered cognitive radio network. D2D relay adapts the amount of energy harvested from the S using TSR protocol while assuming some information leakage to E. The exact and asymptotic closed-from expressions of secrecy outage probability of the proposed system are derived when the channel state information from R to the cellular user link is outdated. Furthermore, we derive novel exact and asymptotic expressions for the power outage probability.