# Wireless Communications and Control for Swarms of Cellular-Connected UAVs

## TL;DR

This paper investigates how to optimize the operation of cellular-connected UAV swarms by jointly considering wireless communication delays and control stability, providing guidelines for stable swarm formation.

## Contribution

It introduces a novel joint communication-control optimization approach that accounts for wireless delay and stability, and derives maximum delay thresholds for UAV swarm stability.

## Key findings

- Maximum allowable delay for stability is identified.
- Reliability of wireless network is quantified as probability of meeting stability criteria.
- Simulation validates the effectiveness of the joint optimization strategy.

## Abstract

By using wireless connectivity through cellular base stations (BSs), swarms of unmanned aerial vehicles (UAVs) can provide a plethora of services ranging from delivery of goods to surveillance. In particular, UAVs in a swarm can utilize wireless communications to collect information, like velocity and heading angle, from surrounding UAVs for coordinating their operations and maintaining target speed and intra-UAV distance. However, due to the uncertainty of the wireless channel, wireless communications among UAVs will experience a transmission delay which can impair the swarm's ability to stabilize system operation. In this paper, the problem of joint communication and control is studied for a swarm of three cellular-connected UAVs positioned in a triangle formation. In particular, a novel approach is proposed for optimizing the swarm's operation while jointly considering the delay of the wireless network and the stability of the control system. Based on this approach, the maximum allowable delay required to prevent the instability of the swarm is determined. Moreover, by using stochastic geometry, the reliability of the wireless network is derived as the probability of meeting the stability requirement of the control system. The simulation results validate the effectiveness of the proposed joint strategy, and help obtain insightful design guidelines on how to form a stable swarm of UAVs.