Performance Analysis of Backscatter-based Coordinated Direct and Relay Transmission with NOMA

Wireless-powered relaying based on backscatter communication has emerged as a viable solution to extend the transmission range of energy-constrained nodes with improved power efficiency. Non-orthogonal multiple access (NOMA), on the other hand, is regarded as a key technology for the next-generation wireless communication system since it offers massive connectivity for ultra-dense networks with improved spectrum efficiency and user fairness. Incorporating backscatter communication into the NOMA system enables more efficient utilization of resources and results in improved performance. We propose backscatter-based coordinated direct and relay transmission with NOMA in this work. The key idea is to backscatter the received downlink signal at the relay to enhance performance of the NOMA user. The proposed system consists of a base station, a strong user, a weak user, and a hybrid backscatter relay. In downlink, the base station communicates directly with the strong user, and with the weak user with the help of a hybrid backscatter relay. The closed-form outage probability (OP) expression are derived for the NOMA users. The asymptotic expression for the OP is also presented. Through Monte-Carlo simulations, the derived analytical expressions are validated.