Design and Optimization of Scheduling and Non-orthogonal Multiple Access Algorithms with Imperfect Channel State Information

Abstract

Non-orthogonal multiple access (NOMA) is a promising candidate technology for 5G cellular systems. In this paper, design and optimization of scheduling and NOMA algorithms is investigated. First, the impact of power allocation for NOMA systems with round-robin scheduling is analyzed. A statistic model is developed for network performance analysis of joint scheduling of spectrum resource and power for NOMA algorithms. Then, proportional fairness (PF) scheduling for NOMA algorithms is proposed with a two-step approach, with its objectives to ensure low computational complexity, high throughput, and user fairness. In the first step, an optimal power allocation strategy is developed with an objective maximizing weighted sum rate. In the second step, three fast and scalable scheduling and user pairing algorithms with QoS guarantee are proposed, in which only a few user pairs are checked for NOMA multiplex. The algorithms are extended to the cases with imperfect channel state estimation and more than two users being multiplexed over one resource block. Numerical results show that the proposed algorithms are significantly faster and more scalable than the existing algorithms, and can maintain a higher throughput gain than orthogonal multiple access.