Optimal UAV's Deployment and Transmit Power Design for Two Users Uplink NOMA Systems.

Fayong Zhao

doi:10.3389/fnbot.2020.599344

Abstract

In order to fully utilize the spectrum resources, this work considers a unmanned aerial vehicle (UAV) uplink communication system based on non-orthogonal multiple access technology (NOMA), in which the UAV receives information from the ground users with a certain flying altitude. As an initial study, we consider a simplified setup with two ground users to draw some insightful results. Explicitly, we first formulate an optimization problem that maximizes the sum throughput subject to each user's transmit power constraint and their corresponding minimum transmission rate requirement. Then, both the optimal transmit power and UAV's deployment location are derived with the aid of employing the Karush-Kuhn-Tucher (KKT) conditions. Simulation results show that the proposed UAV's deployment scheme with the users' power allocation can achieve a higher sum throughput compared with two existing benchmark schemes.

Highlights

Non-orthogonal multiple access (NOMA) is one of the key technologies for future wireless networks, which meets the heterogeneous demands on low latency, massive connectivity, high throughput, etc. (Dai et al, 2015; Ding et al, 2017)
Motivated by above-mentioned reasons, this paper considers an unmanned aerial vehicle (UAV)-enabled uplink NOMA with power multiplexing network, where an UAV is deployed to collect the messages transmitted from the ground users
The following three baseline schemes are invoked: 1) frequency division multiple access (FDMA): The UAV collects the messages in FDMA manner, where both the UAV deployment location and transmit power are jointly optimized; 2) N-FLPO: The scheme in Duan et al (2019), where only the transmit power is optimized while the UAV is fixed at the geometric center of two users, i.e., [0, 0]T; 3) N-LOFP: The UAV collects the messages in NOMA manner, where only the UAV deployment location is optimized while the transmit power is fixed as P1 = 2 mW and P2 = 8 mW

Summary

Introduction

Non-orthogonal multiple access (NOMA) is one of the key technologies for future wireless networks, which meets the heterogeneous demands on low latency, massive connectivity, high throughput, etc. (Dai et al, 2015; Ding et al, 2017). Non-orthogonal multiple access (NOMA) is one of the key technologies for future wireless networks, which meets the heterogeneous demands on low latency, massive connectivity, high throughput, etc. Compared with traditional orthogonal multiple access (OMA) schemes, such as frequency division multiple access (FDMA), time division multiple access (TDMA) and code division multiple access (CDMA), NOMA simultaneously share the time, frequency and code resources. In Ding et al (2014) and Timotheou and Krikidis (2015), downlink NOMA networks were studied, where the authors have demonstrated that NOMA can achieve better outage performance than that of OMA schemes, when both the users’ rate and power allocation are carefully designed. In Zhang et al (2016) and Al-Imari et al (2014), uplink NOMA networks were discussed, where they showed that the uplink NOMA can improve both the spectrum efficiency and fairness index compared with OMA technique

Objectives

Results

Conclusion