[Paper Review] Accessing From The Sky: A Tutorial on UAV Communications for 5G and Beyond

Yong Zeng, Qingqing Wu+1 more|arXiv (Cornell University)|Mar 13, 2019

UAV Applications and Optimization215 references70 citations

TL;DR

This paper provides a comprehensive survey and tutorial on UAV communications for 5G and beyond, detailing two frameworks (cellular-connected UAVs and UAV-assisted wireless), channel/antenna models, and joint trajectory-communication design.

ABSTRACT

Unmanned aerial vehicles (UAVs) have found numerous applications and are expected to bring fertile business opportunities in the next decade. Among various enabling technologies for UAVs, wireless communication is essential and has drawn significantly growing attention in recent years. Compared to the conventional terrestrial communications, UAVs' communications face new challenges due to their high altitude above the ground and great flexibility of movement in the three-dimensional (3D) space. Several critical issues arise, including the line-of-sight (LoS) dominant UAV-ground channels and resultant strong aerial-terrestrial network interference, the distinct communication quality of service (QoS) requirements for UAV control messages versus payload data, the stringent constraints imposed by the size, weight and power (SWAP) limitations of UAVs, as well as the exploitation of the new design degree of freedom (DoF) brought by the highly controllable 3D UAV mobility. In this paper, we give a tutorial overview of the recent advances in UAV communications to address the above issues, with an emphasis on how to integrate UAVs into the forthcoming fifth-generation (5G) and future cellular networks. In particular, we partition our discussions into two promising research and application frameworks of UAV communications, namely UAV-assisted wireless communications and cellular-connected UAVs,where UAVs serve as aerial communication platforms and users, respectively. Furthermore, we point out promising directions for future research and investigation.

Motivation & Objective

• Motivate and contextualize the role of UAVs in 5G and beyond cellular networks.
• Present two main UAV communication paradigms: cellular-connected UAVs and UAV-assisted wireless communications.
• Provide fundamental models (channel, antenna, energy) and a unified framework for joint trajectory and communication design.
• Discuss design opportunities, challenges, and future research directions for UAV communications including interference management and security.
• Highlight the potential integration of UAVs with 3D mobility to enhance coverage, reliability, and efficiency.

Proposed method

• Introduce a unified mathematical framework for joint UAV trajectory design and communication optimization.
• Review air-ground channel and antenna models tailored to UAV scenarios.
• Characterize UAV energy consumption including propulsion versus communication energy.
• Discuss design DoF from UAV mobility and 3D placement to optimize QoS and efficiency.
• Analyze air-ground interference and propose mitigation approaches within cellular-connected and UAV-assisted paradigms.
• Outline energy-efficient design considerations and potential learning-based trajectory optimization approaches.

Experimental results

Research questions

• RQ1 How should UAV air-ground channels be modeled for accurate performance analysis and design?
• RQ2 How can UAV trajectory/placement be jointly optimized with communication scheduling to improve QoS and efficiency?
• RQ3 What are the key challenges and opportunities when integrating UAVs as aerial users versus aerial platforms in cellular networks?
• RQ4 How can interference, security, and SWAP constraints be managed in UAV-enabled 5G-and-beyond networks?
• RQ5 What future research directions (e.g., learning-based methods) are most promising for UAV communications?

Key findings

• Provides a unified framework for UAV trajectory and communication co-design applicable to both UAV-assisted and cellular-connected paradigms.
• Identifies high-altitude LoS-dominant channels as both an opportunity (reliable links, macro-diversity) and a challenge (interference, security threats).
• Highlights the need for 3D placement/trajectory design and energy-efficient hardware to cope with SWAP constraints.
• Discusses the potential of leveraging cellular networks (5G/6G) for ubiquitous UAV connectivity and localization services.
• Outlines opportunities in learning-based UAV trajectory optimization and communication design to handle dynamic networks.
• Summarizes existing field trials, standardization efforts, and cross-layer design considerations for UAV integration into cellular networks.