Resource Allocation in Power-Beacon-Assisted IoT Networks With Nonorthogonal Multiple Access

Abstract

We study a wireless powered network, including a power beacon (PB), an energy-harvesting (EH)-based source, and multiple users. To improve the spectrum efficiency of the network as well as for practical implementation consideration, two users are paired to perform nonorthogonal multiple access (NOMA) transmission. Specifically, the NOMA-based transmission protocol consists of two phases, where the source harvests energy from the PB in the first phase, and then sends a superimposed signal to the paired users in the second phase. We derive exact and asymptotic closed-form expressions of the average throughput for each paired user. Then, the joint optimization problem for the time and power allocation is investigated to achieve the optimal fair performance of the paired users. To provide a benchmark, optimal resource allocation strategy for an orthogonal multiple access (OMA)-based transmission protocol is also studied. Simulation results confirm the validity of our analytical derivations and show that the considered network with NOMA transmissions is superior to that with OMA transmissions, especially when the transmit power of the PB is low and the paired users have significant differences in channel gain.