Power Allocation Optimization and Decoding Order Selection in Uplink C-NOMA Networks

In this letter, we investigate the power allocation and decoding order at the base station (BS) of two-user uplink (UL) cooperative non-orthogonal multiple access (C-NOMA)-based cellular networks. We formulate a joint optimization problem aiming at maximizing the minimum user achievable rate. Given that the problem at hand is non-convex, as an alternative, we derive low-complexity and near optimal analytical expressions for the power allocation coefficients. We demonstrate through numerical results that the proposed scheme provides superior performance in comparison with the traditional UL NOMA. We also demonstrate that, in UL C-NOMA, decoding the far NOMA user first at the BS provides the best performance.