Fundamental Tradeoffs in Communication and Trajectory Design for UAV-Enabled Wireless Network (1805.07038v1)

Abstract: The use of unmanned aerial vehicles (UAVs) as aerial communication platforms is of high practical value for future wireless systems such as 5G, especially for swift and on-demand deployment in temporary events and emergency situations. Compared to traditional terrestrial base stations (BSs) in cellular network, UAV-mounted aerial BSs possess stronger line-of-sight (LoS) links with the ground users due to their high altitude as well as high and flexible mobility in three-dimensional (3D) space, which can be exploited to enhance the communication performance. On the other hand, unlike terrestrial BSs that have reliable power supply, aerial BSs in practice have limited on-board energy, but require significant propulsion energy to stay airborne and support high mobility. Motivated by the above new considerations, this article aims to revisit some fundamental tradeoffs in UAV-enabled communication and trajectory design. Specifically, it is shown that communication throughput, delay, and (propulsion) energy consumption can be traded off among each other by adopting different UAV trajectory designs, which sheds new light on their traditional tradeoffs in terrestrial communication. Promising directions for future research are also discussed.

• The paper demonstrates that optimizing UAV trajectories strategically balances throughput and delay in dynamic wireless environments.
• The paper reveals that varying UAV propulsion energy, particularly between fixed-wing and rotary-wing designs, underpins the throughput-energy tradeoff.
• The paper highlights that adaptive trajectory planning and multi-UAV coordination efficiently manage delay-energy tradeoffs and mitigate interference.

UAV-Enabled Wireless Networks: Communication and Trajectory Design Tradeoffs

The paper "Fundamental Tradeoffs in Communication and Trajectory Design for UAV-Enabled Wireless Network" by Qingqing Wu, Liang Liu, and Rui Zhang presents a thorough investigation into the tradeoffs encountered in communication and trajectory design for UAV-enabled wireless networks, particularly in the context of modern and future wireless systems like 5G networks. Unmanned aerial vehicles (UAVs) provide valuable advantages over traditional terrestrial base stations through enhanced line-of-sight communication links due to their altitude and mobility. However, the paper recognizes the challenges posed by limited onboard energy and the substantial propulsion energy required to maintain these aerial platforms.

Overview of UAV-Enabled Wireless Networks

The introduction establishes UAVs as flexible and mobile communication platforms, beneficial for scenarios requiring rapid deployment, such as temporary events or emergencies. Thanks to their inherent mobility and line-of-sight communication capabilities, UAVs can significantly bolster wireless communication, offering improved connectivity with large numbers of terrestrial devices.

Throughput, Delay, and Energy Tradeoffs

The core of the paper addresses three fundamental tradeoffs: throughput-delay, throughput-energy, and delay-energy, in relation to UAVs. The unique characteristics of UAVs, including controllable mobility and high propulsion power demands, bring new dimensions to these tradeoffs compared to traditional terrestrial networks.

1. Throughput-Delay Tradeoff: UAVs can navigate strategically to minimize distances to ground users, enhancing throughput but potentially increasing communication latency due to movement. The analysis highlights how trajectory optimizations allow UAVs to better balance throughput with tolerable delay requirements.
2. Throughput-Energy Tradeoff: UAV trajectory design directly impacts propulsion energy consumption. The paper outlines the differences in energy consumption models between fixed-wing and rotary-wing UAVs, portraying how higher speeds can increase energy requirements, thus influencing strategic trajectory decisions for energy efficiency without compromising throughput.
3. Delay-Energy Tradeoff: Considering the propulsion energy is paramount, the paper discusses how UAVs can mitigate delays by adjusting speeds and paths, impacting energy usage. Effective trajectory planning allows UAVs to optimize energy expenditure while meeting user delay tolerances.

Multi-UAV Deployment and Technological Implications

The research further explores the dynamic use of multiple UAVs, emphasizing inter-UAV interference coordination techniques to maximize throughput while managing interference within shared frequency bands. This requires innovative approaches like cooperative beamforming and agile trajectory designs, each offering resilience and adaptability in complex network environments.

Future Directions

The paper suggests areas for future exploration, including non-orthogonal multiple access and advanced trajectory designs in non-LoS environments. Discussions also delve into potential integrations of UAVs powered through alternative means, such as solar energy, offering pathways to mitigate energy constraints. Furthermore, incorporating considerations like cost-efficiency and deployment scalability in larger UAV networks presents promising research opportunities.

Conclusion

In summary, this paper provides an insightful exploration into UAV-enabled wireless networks, focusing on fundamental tradeoffs between communication performance metrics and energy resources. It introduces robust frameworks and thought-provoking guidance for UAV trajectory designs that optimize these tradeoffs. The outcomes pave the way for significant advancements in UAV network deployments and innovative wireless communication strategies, fostering continued research into this rapidly evolving field.