Power beacon assisted wireless power cooperative relaying using NOMA with hardware impairments and imperfect CSI

Abstract

In this paper, we study the joint impact of residual hardware impairments (RHIs) and imperfect channel state information (ICSI) on cooperative non-orthogonal multiple access (NOMA) multi-relay networks. The communication between source and destinations is achieved with the aid of multiple relays with limited energy which can harvest energy from a nearby power beacon (PB). Two representative scenarios are considered: (i) The communication between the base station (BS) and the far users are realized only by the relays while the near users can receive information from both the BS and relays; (ii) The direct links between the BS and the far users exist. To evaluate the performance of the considered network, the exact analytical expressions of the outage probability for the far users and the near users are derived in closed-form. To gain deeper insights, we carry out the asymptotic outage analysis in the high signal-to-noise ratio (SNR) regime and the diversity orders for the two cases are discussed. Based on the derived results, we investigate the throughput by quantifying the impact of RHIs and ICSI on the network performance. Numerous results are presented to verify the theoretical analyses and show: (1) There exist error floors of the outage probability caused by RHIs and ICSI; (2) The direct links can improve the system performance of the two scenarios; (3) There exists an optimal power allocation factor to maximize the outage performance, especially for the far users.