Outage Performance Analysis of Cooperative NOMA-SWIPT in Coordinated Downlink Dual-Cell Systems

‍ ‍This study investigated the outage performance of cooperative downlink communications with non-orthogonal multiple access （NOMA） and simultaneous wireless information and power transfer （SWIPT） in the coordinated dual-cell systems of a femtocell network （FN）. A downlink scheme was developed for edge users with the aid of an adjacent base station and random center user of the source base station. After ensuring the priority of their own communication quality， center users provide a relaying service by harvesting energy based on the power domain NOMA-SWIPT protocol. This scheme is divided into two time slots. In the first time slot， two base stations broadcast the superimposed signal to all users， and the center users acting as relay devices decode the signal and energy harvest. In the second time slot， the center users use the energy collected in the first time slot as an additional power resource to encode and forward the edge user information， while prioritizing their own requirements. Based on the center users’ location model in a spatial homogeneous Poisson point process （PPP）， the average outage probabilities for both the center users and edge users were derived and validated using Monte Carlo simulations. The relationships between some simulation paraments （the distribution radius of center users， threshold rate of users， path loss exponent， etc.） and the average outage probabilities for center users and edge users were analyzed. The results showed that the proposed scheme could improve the downlink outage performance of edge users， along with the system downlink throughput.