UAV-Ground BS Coordinated NOMA with Joint User Scheduling, Power Allocation and Trajectory Design

Abstract

We propose an unmanned aerial vehicle (UAV)ground base station (GBS) coordinated NOMA scheme where UAV and GBS are jointly serve the cell-edge users. To the best of our knowledge, this is the first work to investigate airground BSs coordination for UAV-assisted NOMA systems, by taking advantage of the interference between UAV and GBS. Therefore, the proposed UAV-GBS coordinated NOMA scheme achieves much higher sum rate of cell-edge users than the noncoordinated UAV-assisted NOMA schemes where interference is suppressed as much as possible. The proposed scheme also leads to better channel condition and more flexible and cost-effective interference management, compared to GBSs coordinated NOMA. We conduct joint optimization of power allocation, user scheduling and UAV trajectory for the UAV-GBS coordinated system. A closed-form optimal solution to power allocation is derived. In addition, a dedicated successive interference cancellation (SIC) ordering approach is proposed. It is proven that the selection of a cell-center user with higher SIC order contributes to a higher rate of cell-edge user, based on which an SIC order based user scheduling algorithm for both cell-center and cell-edge users is presented.

Joint Trajectory and Link Scheduling Optimization in UAV Networks

“…However, the UAV can serve only two users simultaneously. In [19], the authors consider a downlink UAV-assisted NOMA system, where a UAV and a NOMA-aided ground BS (GBS) coordinate and transmit together to multiple ground users. According to the distance to GBS, ground users are divided into cell-center users and cell-edge users.…”

“…According to the distance to GBS, ground users are divided into cell-center users and cell-edge users. The aim of [19] is to maximize the sum rate of cell-edge users by taking advantage of the interference between UAV and GBS. However, the system setting and the aim of [19] are different from our work.…”

“…The aim of [19] is to maximize the sum rate of cell-edge users by taking advantage of the interference between UAV and GBS. However, the system setting and the aim of [19] are different from our work. The authors of [20] consider a UAV-based NOMA downlink wireless network, where the UAV flies at a fixed height.…”