Cooperative partner selection for coordinated direct and relayed transmission with NOMA and energy pricing

This paper considers a non-orthogonal multiple access (NOMA) and coordinated direct and relayed transmission (CDRT) based wireless network with one near user, one far user, and multiple idle users (potential relays). We propose a joint cooperative partner (relay) selection and power allocation scheme based on energy pricing. We derive the optimal power allocation between the base station (BS) and the active relay in the two-time slots and select the optimal cooperative relay according to minimum cost criteria. Simulation results show that the proposed scheme can extend the network lifetime by more than 50 % compared to other methods in some cases.