Joint User-Channel Assignment and Power Allocation for Non-Orthogonal Multiple Access Relaying Networks

Non-orthogonal multiple access (NOMA) technique, which is known to raise the performance of frequency spectrum constrained wireless communication networks, has obtained wide attention. In this paper, a NOMA-based resource allocation problem in the decode-and-forward relaying downlink network is considered. We aim to maximize the average user transmission rate, subject to the total system power constraint and users' quality of service requirement. A joint user-channel assignment and power allocation problem is formulated, which leads to an NP-hard problem requiring an exhaustive search. To tackle this problem, we adopt a decouple optimization method to separate the joint resource problem into two subproblems, a user-channel assignment problem, and a power allocation problem. After solving the two subproblems, a joint alternating optimization algorithm is proposed with low complexity. The simulation results show that the proposed joint optimal scheme can efficiently improve system performance in the limited channels of multiple users relaying networks.