Coverage performance of cooperative NOMA MmWave networks with wireless power transfer

Abstract

The millimeter-wave (mmWave) plays a vital role in the fifth generation (5G) and beyond-5G (B5G) cellular networks, which is also attractive for wireless power transfer (WPT) since the mmWave base stations (BSs) are usually equipped with large antenna arrays. This paper studies a wireless-powered mmWave communication system with non-orthogonal multiple access (NOMA) cooperative transmission. In this system, the BS intends to transmit signals to a near-wireless device (WD) and a far-WD simultaneously, where the location of near-WD is fixed that can be treated as a relay for cooperatively transferring the signal to a far-WD, which is far away from the BS. Since there are multiple far-WDs in the region, two pairing schemes based on the distance between the near and far WDs are investigated, i.e., 1) near-WD pairs with the nearest far-WD (NNF); 2) near-WD pairs with a randomly selected far-WD (NRF). We evaluate the downlink transmission performance by assuming that the near-WD is energy-constrained and performs cooperative transmission after scavenging sufficient radio frequency (RF) energy while successfully decoding both the signals for near-WD and far-WD. Since the near-WD may accumulate sufficient energy in several transmission blocks, the processes of charging and discharging are analyzed by a finite-state Markov chain. On this basis, the performance of two WD pairing schemes is analyzed by deriving the exact expressions of coverage probabilities for both the near-WD and far-WD. The simulation results show that the considered mmWave cooperative communication system with NOMA schemes can achieve a better coverage performance than the compared OMA and other schemes, while the coverage probability of far-WD with the NNF pairing scheme is better than that with the NRF pairing scheme.