Full-Duplex Cooperative Non-Orthogonal Multiple Access System With Feasible Successive Interference Cancellation

Non-orthogonal multiple access (NOMA) is a promising radio access scheme for future mobile networks due to its high spectral efficiency, but the weak user suffers poor performance due to the interference and poor channel quality. Full-duplex cooperative NOMA (FD C-NOMA) is an attractive solution by allowing the strong user to relay the weak user's signal simultaneously, but most existing works made an impractical assumption that the signals from the base station (BS) and the strong user can be perfectly resolved and combined at the weak user. Considering feasible successive interference cancellation (SIC) operation, we propose a two-phase FD C-NOMA system where the BS only transmits a new signal for the strong user in the second phase, such that the weak user can perform SIC to obtain its own signal. A sum-rate maximization for this proposed system is investigated and a low-complexity closed form solution is derived under the total BS transmission power and proportional rate constraints. Numerical simulation results show that the proposed FD C-NOMA system model attains better sum-rate performance compared to other schemes.