UAV-Aided NOMA Networks with Optimization of Trajectory and Precoding

The explosive data traffic and connections in 5G networks require the use of non-orthogonal multiple access (NOMA) to accommodate more users. Unmanned aerial vehicle (UAV) can be exploited with NOMA to improve the situation further. In this paper, we propose a UAV-assisted NOMA network, in which the UAV and base station (BS) cooperate with each other to serve ground users simultaneously. First, the sum rate of the UAV-served users is maximized via alternate user scheduling and UAV trajectory, with its interference to the BS-served users below a threshold. Then, the optimal NOMA precoding vectors are obtained to cancel the interference from the BS to the UAV-served user. Numerical results are provided to evaluate the effectiveness of the proposed algorithms for the hybrid NOMA and UAV network.

I. Introduction

As one of the crucial techniques for 5G, non-orthogonal multiple access (NOMA) can not only significantly improve the spectrum efficiency but also allow more users or devices to access the network [1], [2]. Different from the conventional orthogonal multiple access (OMA), NOMA is built upon the idea that multiple users can simultaneously share one resource block, such as a subcarrier or a spreading code [1]. These users are multiplexed in the power domain, and successive interference cancellation (SIC) is required at the receiver for demodulation [2].