Secrecy Outage Performance Analysis of Cooperative NOMA Networks With SWIPT

In this letter, we investigate the secrecy outage performance of a cooperative non-orthogonal multiple access (NOMA) network, where a base station (BS) communicates with multiple cell-centre users and a cell-edge user in the presence of an eavesdropper. It is assumed that there is no direct link between the BS and the cell-edge user, and thus one of the cell-centre users is selected to act as a relay for the cell-edge user. Particularly, the selected cell-centre user adopts the simultaneous wireless information and power transfer (SWIPT) for decoding information and harvesting energy for forwarding. The closed-form approximate expression for the system secrecy outage probability is derived under the max-min user selection (MMUS) strategy. The theoretical results are verified by simulations, and it is shown that the MMUS strategy outperforms various benchmark strategies.