UAV-Mounted Aerial Relays in Military Communications: A Comprehensive Survey

TL;DR

This survey reviews UAV-mounted aerial relays in military communications, comparing them to traditional relays, introducing a new evaluation metric, and proposing a decision framework for optimal relay selection in various military scenarios.

Contribution

It provides a comprehensive comparison of AR and TR systems, introduces the MCRES metric, and presents a decision-making algorithm for selecting the best relay type based on mission needs.

Findings

UAV-mounted relays offer enhanced coverage and flexibility over traditional relays.

The MCRES metric effectively evaluates relay suitability for different scenarios.

The decision framework improves relay selection accuracy in military operations.

Abstract

Relays are pivotal in military communication networks, expanding coverage and ensuring reliable connectivity in challenging operational environments. While traditional terrestrial relays (TR) are constrained by fixed locations and vulnerability to physical obstructions, unmanned aerial vehicle (UAV)-mounted aerial relays (AR) offer a dynamic and flexible alternative by operating above obstacles and adapting to changing battlefield conditions. This paper provides a comprehensive survey of AR systems in military communications, presenting a detailed comparison between AR and TR paradigms and examining two specific AR technologies: active aerial relays (AAR) and aerial reconfigurable intelligent surface (ARIS) relays. The survey delves into their operation, benefits, challenges, and military applications, supported by a qualitative analysis across metrics such as coverage, flexibility, security, and cost. A novel multi-dimensional metric, the mission-critical relay effectiveness score (MCRES), is introduced as a quantitative method for evaluating relay suitability based on mission-specific weights for critical attributes like mobility, jamming resilience, deployment speed, stealth, coverage, and autonomy. Furthermore, we present Algorithm 1, a decision-making framework that leverages the MCRES to guide the systematic selection of the optimal relay type, AR or TR, and subsequently AAR or ARIS, tailored to the unique demands of a given military scenario, such as dynamic battlefield operations, electronic warfare, or covert missions. Finally, the paper addresses current implementation challenges and outlines promising future research directions to advance the deployment of robust and resilient UAV-mounted relay systems in contested military environments.