Low-complexity joint user and power scheduling in downlink NOMA over fading channels

TL;DR

This paper proposes low-complexity algorithms for joint user and power scheduling in downlink NOMA over fading channels, optimizing sum rate while guaranteeing minimum data rates, with near-optimal performance demonstrated through simulations.

Contribution

It introduces a stochastic optimization-based opportunistic scheduling algorithm and a heuristic low-complexity user and power allocation method for downlink NOMA.

Findings

USPA achieves near-optimal sum rate performance.

OUPS guarantees minimum average data rates.

Algorithms have very low computational complexity.

Abstract

Non-orthogonal multiple access (NOMA) has been considered one of the most promising radio access techniques for next-generation cellular networks. In this paper, we study the joint user and power scheduling for downlink NOMA over fading channels. Specifically, we focus on a stochastic optimization problem to maximize the weighted average sum rate while ensuring given minimum average data rates of users. To address this problem, we first develop an opportunistic user and power scheduling algorithm (OUPS) based on the duality and stochastic optimization theory. By OUPS, the stochastic problem is transformed into a series of deterministic ones for the instantaneous weighted sum rate maximization for each slot. Thus, we additionally develop a heuristic algorithm with very low computational complexity, called user selection and power allocation algorithm (USPA), for the instantaneous weighted sum rate maximization problem. Via simulation results, we demonstrate that USPA provides near-optimal performance with very low computational complexity, and OUPS well guarantees given minimum average data rates.