On the Performance of Multi-Relay Cellular Networks with NOMA

In this paper, a new receiver detection scheme for the cooperative multi-relay system using non-orthogonal multiple access (CMRS-NOMA) is proposed in the cellular networks. In the proposed cellular networks, the base station (BS) would like to communicate multiple users via multiple relays, while that the direct link between BS and users are not considered. Specifically, we further assume that of two relays in approaching scopes to the user can assist the transmission, since that other relays are out of the cooperation scopes. By this way, each user and two corresponding relays can be implemented as one group. In addition, the source simultaneously transmits the superposition coded signals to the relay nodes. After receptions, multi-relay nodes decode the symbols by applying the successive interference cancellation (SIC), and then reconstruct them into new NOMA signals, which will be forwarded to the receiving nodes. The users jointly decode the information symbols received from two adjacent relay nodes with a practical and simple operation, also derive the closed-form expressions of the sum-rate (SR). Qualitative numerical results corroborating our theoretical analysis show that the proposed scheme significantly improves the SR performance compared with the existing works.