Energy Efficient Full-Duplex UAV Relaying Networks Under Load-Carry-and-Delivery Scheme

Nan Qi,Guanghua Yang,Theodoros A Tsiftsis,Mei Wang,Wen-Jing Wang,Rugui Yao

doi:10.1109/access.2020.2986349

Abstract

In this paper, an energy-efficient full-duplex (FD) unmanned aerial vehicle (UAV) relaying network is proposed, where UAV acts as a mobile relay and assists information exchange between two transceivers. Specifically, the load-carry-and-delivery scheme is applied to positively take advantage of the time-varying channel gain in delay-tolerant networks; meanwhile, the FD communication policy is used to potentially further increase the energy efficiency (EE). In particular, the self-interference channel gains follow the complex Gaussian distribution instead of being constant. The EE is first rigorously derived and then, the optimum flight speed is determined under the information causality constraint to maximize the EE. Numerical results demonstrate that the proposed scheme outperforms the half-duplex as well as static schemes in terms of the EE. In addition, the impact of the self-interference cancellation factor on the EE is also demonstrated, which provides valuable insights for the system design of UAV-assisted relaying networks.

Highlights

Nowadays, commercial unmanned aerial vehicle (UAV) for various applications have been developed, including UAV for smart agriculture/ forestry, security/fire monitoring and express transportation
We assume that the amplify-and-forward (AF) policy is employed at UAV relay, which works in the full-duplex mode
The parameter settings are applicable to practical engineering implementations and given in Table 2, unless otherwise specified

Summary

INTRODUCTION

Commercial UAVs for various applications have been developed, including UAV for smart agriculture/ forestry, security/fire monitoring and express transportation. In [11]–[13], energy-efficient terrestrial half-duplex relaying (HDR) transmissions were investigated, where the transmitting power was optimized. The throughput of FDR networks have been proved to outperform that of the half-duplex scheme in some communication scenario (i.e. higher channel gains, lower selfinterference (SI)) [21]–[23] They mainly focus on the terrestrial relays (i.e. static relays). In [24], the full-duplex relaying (FDR) transmission sum-rate under the transmit power budget was investigated, where the self-interference channel gains were fixed, which may not be practical [25]. The UAV works in an FDR fashion to fully exploit the relaying capacity and further improve the energy efficiency of data transmission. The detailed offloading and loading schemes in the first stage will be respectively presented in subsections III-A and III-B

DATA OFFLOADING

EE FORMULATION AND ANALYSIS

OFFLOADING SUM-BITS DERIVATION

LOADING SUM-BITS DERIVATION

NUMERICAL RESULTS

CONCLUSIONS