Dynamic Power and Channel Allocation for Downlink Multi-Channel NOMA Systems

Abstract

Non-orthogonal multiple access (NOMA) has been investigated as a candidate radio access technology for the fifth generation mobile networks. In this paper, we focus on the dynamic power and channel allocation (DPCA) schemes for downlink multi-channel NOMA (MC-NOMA) systems. First, we assume an ideal MC-NOMA system with an arbitrary number of multiplexed users per subchannel and develop the optimal DPCA scheme for it based on a low-complexity inter-channel power allocation algorithm. Its performance serves as an upper bound for practical MC-NOMA systems where the number of multiplexed users per subchannel is limited. We utilize this optimal scheme and propose a user preselection (UP)-based DPCA scheme for practical systems. The performance of the UP-based DPCA scheme is evaluated by simulations and compared with the optimal scheme in the literature and the upper bound obtained in the ideal system. It achieves close-to-optimal performance with extremely low computational complexity. Moreover, we analyze the impacts of multi-user and multi-channel diversities on the system performance, serving as a guideline for practical deployments and configurations of MC-NOMA systems.