Wireless-Powered Reconfigurable-Intelligent-Surface-Aided Cognitive NOMA Network With Hardware Impairments: IBL and FBL Analysis

This article investigates the performance of a wireless-powered reconfigurable intelligent surface (RIS)-assisted cognitive-radio (CR)-nonorthogonal multiple access (NOMA) network with hardware impairments (HIs). In the secondary network, the secondary source harvests its energy wirelessly from the multiantenna power beacon for its operation. The secondary source operates in underlay mode to communicate with the near user through a direct link, and the far user is served with the help of RIS, under the multiantenna primary user constraint. The performance of the considered system is analyzed using different assumptions of blocklengths, HIs, and successive interference cancellation (SIC). In other words, we have considered the infinite blocklength (IBL) and finite blocklength (FBL) transmission under the practical constraints of HI and imperfect SIC. We have derived the novel closed-form expression for the outage probability (OP) and system throughput for the IBL transmission. In contrast, for the FBL transmission, we have derived the closed-form expression for the average block error rate (ABLER), goodput, latency, and reliability. The asymptotic analysis for the OP and ABLER is also presented in two different power-setting scenarios: 1) when the transmit power of the power beacon goes to infinity and 2) when the maximum interference constraint of the primary network goes to infinity. Monte Carlo simulations are performed to verify the analytical results. Numerical results indicate the superior performance of the combination of RIS and NOMA in the considered system over RIS-assisted orthogonal multiple access (OMA) schemes. The impact of other parameters, such as the number of antennas at the power beacon, the number of antennas at the primary user, the number of RIS elements, time-splitting factor, HIs, blocklength, and imperfect SIC on the system performance, is also examined.