Capacity and Delay of Unmanned Aerial Vehicle Networks with Mobility (2311.15017v1)

Abstract: Unmanned aerial vehicles (UAVs) are widely exploited in environment monitoring, search-and-rescue, etc. However, the mobility and short flight duration of UAVs bring challenges for UAV networking. In this paper, we study the UAV networks with n UAVs acting as aerial sensors. UAVs generally have short flight duration and need to frequently get energy replenishment from the control station. Hence the returning UAVs bring the data of the UAVs along the returning paths to the control station with a store-carry-and-forward (SCF) mode. A critical range for the distance between the UAV and the control station is discovered. Within the critical range, the per-node capacity of the SCF mode is O(n/log n) times higher than that of the multi-hop mode. However, the per-node capacity of the SCF mode outside the critical range decreases with the distance between the UAV and the control station. To eliminate the critical range, a mobility control scheme is proposed such that the capacity scaling laws of the SCF mode are the same for all UAVs, which improves the capacity performance of UAV networks. Moreover, the delay of the SCF mode is derived. The impact of the size of the entire region, the velocity of UAVs, the number of UAVs and the flight duration of UAVs on the delay of SCF mode is analyzed. This paper reveals that the mobility and short flight duration of UAVs have beneficial effects on the performance of UAV networks, which may motivate the study of SCF schemes for UAV networks.

• The paper introduces a SCF transmission mode that boosts per-node capacity by leveraging UAV returns within a critical range.
• It shows that designed mobility control strategies can equalize network capacity regardless of UAV distance from the control station.
• The study reveals that network delay decreases with more UAVs and increases with greater flight range and lower speeds.

Introduction

Unmanned Aerial Vehicles (UAVs) are increasingly used for various functions such as environmental monitoring and search-and-rescue operations. These applications often involve a network of UAVs deployed as aerial sensors that collect and transmit data back to a control station. A key challenge faced by UAV networks is their mobility and limited flight duration, which necessitates frequent returns to the control station for energy replenishment. In this context, a store-carry-and-forward (SCF) transmission mode is proposed to enhance the network's capacity and manage data delay effectively.

Network Capacity with SCF Mode

The SCF mode takes advantage of the UAVs' regular returns to the control station by having these UAVs carry data from other UAVs en route. This paper discovers that within a critical range of the control station, the per-node capacity of the SCF mode significantly exceeds that of the conventional multi-hop mode by Θ(log n). However, outside of this critical range, the capacity of the SCF mode decreases with increasing distance between UAVs and the control station due to fewer interactions with returning UAVs. This indicates an inhomogeneity in the network capacity depending on the UAVs' proximity to the control station.

Mobility Control Improves Capacity

A mobility control scheme is introduced to address the capacity inhomogeneity issue. UAVs employ designed trajectories that increase encounters with returning UAVs, effectively eliminating the critical range and equalizing capacity across the network. This scheme allows all UAVs to enjoy the same high per-node capacity, scaling equally irrespective of their distance from the control station.

Delay Analysis

Additionally, the paper examines the delay characteristics of UAV networks operating in SCF mode. Analytical results reveal that the delay is influenced by factors such as the region's size, UAV velocity, the number of UAVs, and flight duration. Notably, the delay tends to decrease with an increasing number of UAVs and increases with greater flight range or lower velocities.

Conclusion

The SCF transmission mode leverages the inherent features of UAVs, such as mobility and short flights, to improve network performance, contrary to typical challenges these features pose for network protocol design. By adopting suitable mobility control strategies, the UAV network's capacity performance can be significantly enhanced, which could be a step forward in the SCF transmission scheme research for future UAV networks.