Secure and Reliable Transmission in mmWave NOMA Relay Networks With SWIPT

In this article, we consider the millimeter-wave simultaneous wireless information and power transfer nonorthogonal multiple access (NOMA) relay networks in the presence of multiple passive eavesdroppers, where the near and far Internet of Things (IoT) devices with different communication requirements are served by one source with the help of the relays, and stochastic geometry is used to characterize the distribution of multiple nodes. First, a NOMA pairing and relay selection scheme is designed. Then, the closed-form expressions for the energy-information coverage probability (EICP) and the effective secrecy throughput of the near IoT devices are derived. Finally, the EICPs of the far IoT device under random relay selection and opportunistic relay selection schemes are obtained. Moreover, the asymptotic expressions of the EICP for both the near and far IoT devices are derived, which show that the asymptotic EICP when the number of antennas at the source or relay tends to infinity is only dependent on the location distribution of nodes and blockage environment. The simulation results show that NOMA can outperform orthogonal multiple access, and the advantage of the opportunistic relay selection scheme over the random relay selection scheme is more obvious when the density of the relay is relatively large.