Outage probability and throughput of cooperative non-orthogonal multiple access with moving relay in heterogeneous network

The demand of high data rate, high quality of service (QoS), and seamless connectivity are growing continuously for vehicular communication over the last few years. Moving relay (MR) is one of the promising techniques to achieve these demands. In the past, heterogeneous network (HetNet) models with one MR on the top of the train have been proposed for high-speed railway (HSR) using the orthogonal multiple access (OMA) technique. Cooperative non-orthogonal multiple access (NOMA) is a promising multiple access technique for next-generation wireless networks. This paper proposes one MR-based HetNet model using the NOMA over Rayleigh fading channels for downlink communication. Here, half-duplex (HD) type amplify and forward (AF) relay is used as MR for investigation. We derive the outage probability of a train-user using the successive interference cancellation (SIC) technique and the outage probability of a cell-edge-user by using both direct and indirect signals via MR. The system throughput of the proposed NOMA system is also simulated by considering the effects of perfect and imperfect SIC. The simulation results show that cooperative NOMA provides lower outage performance in comparison with cooperative OMA and outage of vehicular user decreases with lower value of residual interference (RI). Also, the system throughput of the NOMA system decreases with higher values of residual interference. We use Monte Carlo simulation to verify the derived analytical results.