Cyclical Multiple Access in UAV-Aided Communications: A Throughput-Delay Tradeoff (1608.03180v2)

Abstract: This letter studies a wireless system consisting of distributed ground terminals (GTs) communicating with an unmanned aerial vehicle (UAV) that serves as a mobile base station (BS). The UAV flies cyclically above the GTs at a fixed altitude, which results in a cyclical pattern of the strength of the UAV-GT channels. To exploit such periodic channel variations, we propose a new cyclical multiple access (CMA) scheme to schedule the communications between the UAV and GTs in a cyclical time-division manner based on the flying UAV's position. The time allocations to different GTs are optimized to maximize their minimum throughput. It is revealed that there is a fundamental tradeoff between throughput and access delay in the proposed CMA. Simulation results show significant throughput gains over the case of a static UAV BS in delay-tolerant applications.

• The paper proposes a novel cyclical multiple access (CMA) scheme that leverages periodic UAV trajectories to significantly enhance throughput over static base stations.
• It analyzes the inherent tradeoff between throughput and access delay, demonstrating that UAV mobility improves channel quality at the cost of increased delay.
• An algorithm optimizes time allocations among ground terminals to ensure equitable throughput distribution, paving the way for more efficient UAV-aided communications.

Cyclical Multiple Access in UAV-Aided Communications: A Throughput-Delay Tradeoff

The paper "Cyclical Multiple Access in UAV-Aided Communications: A Throughput-Delay Tradeoff" presents a paper on enhancing communications in wireless systems utilizing unmanned aerial vehicles (UAVs) as mobile base stations (BS). The focus is on distributed ground terminals (GTs) communicating with a periodically flying UAV, leveraging cyclical variations in UAV-GT channel strengths to optimize communications.

Research Focus and Methodology

The paper introduces a novel cyclical multiple access (CMA) scheme that schedules communications based on the UAV's position. The UAV follows a fixed-altitude cyclical trajectory above the GTs, inducing periodic channel fluctuations. This method contrasts with the static UAV BS approach and is designed to optimize time allocation for different GTs to maximize the minimum throughput. The simulation-based analysis investigates the inherent tradeoff between throughput maximization and access delay.

Key Findings

The research highlights several pivotal findings:

1. Throughput Gains: The proposed CMA scheme provides significant throughput improvements over a static UAV BS, particularly in delay-tolerant scenarios. The mobile nature of the UAV enhances channel quality by exploiting favorable UAV-GT proximity during the cyclical flight.
2. Tradeoff Analysis: The paper effectively delineates the fundamental tradeoff between throughput and access delay. The introduction of cyclical UAV trajectories increases access delays relative to static BS configurations, accentuated by larger trajectory lengths.
3. Algorithmic Optimization: An algorithm is employed to optimize the time allocations across UAV positions, achieving an equitable throughput distribution among GTs and maximizing the minimum throughput.

Practical and Theoretical Implications

Practically, UAV-assisted mobile BS systems with CMA are well-suited for applications tolerant to varying access delays, such as large data transfers or periodic sensing operations. The UAV's mobility can drastically enhance connectivity in areas lacking infrastructure, improving the efficiency and responsiveness of wireless networks in dynamic environments.

Theoretically, the work advances understanding of mobile base stations' contributions to communication channel dynamics. It lays the groundwork for future enhancements that may include more complex UAV trajectories, variable altitude controls, and potentially cooperative deployments of multiple UAV systems.

Future Prospects

The paper identifies several avenues for future exploration. Future work could extend to non-uniformly distributed GTs across two or three-dimensional spaces. Additionally, other cyclical access methods beyond TDMA could be explored, together with adaptive speed and altitude control mechanisms for UAVs.

In conclusion, this paper contributes valuable insights into the integration of UAVs in wireless communications and offers a compelling strategy for leveraging UAV mobility to enhance throughput while acknowledging the associated increase in access delay. As UAV technologies advance and their deployment costs continue to decrease, the relevance and applicability of such studies will inevitably grow, promising more adaptive and efficient communication networks.