Multichannel Resource Allocation for Downlink Non-Orthogonal Multiple Access Systems

Abstract

Non-orthogonal multiple access (NOMA) enables user multiplexing in the power domain via successive interference cancellation (SIC). The key to achieve the full benefit of NOMA is resource allocation, including power allocation and channel assignment for all users, which leads to difficult mixed integer programs. In the literature, the optimal power allocation has only been investigated for users on a single channel (or in one group), while the joint optimization of power allocation and channel assignment generally requires an exhaustive research. In this paper, we investigate resource allocation in downlink NOMA systems. We analytically characterize the optimal power allocation in closed-form for sum rate maximization with weights or quality of service (QoS) constraints. Furthermore, we also propose a low-complexity efficient method to jointly optimize channel assignment and power allocation in NOMA systems by incorporating the matching algorithm with the optimal multichannel power allocation. Simulation results show that the joint resource optimization using our optimal power allocation yields better performance than the existing schemes.