Channel Access Strategies for Control-Communication Co-Designed Networks

TL;DR

This paper presents a co-design framework for wireless networked control systems, optimizing channel access strategies like ALOHA protocols to improve control performance amid interference and transmission uncertainties.

Contribution

It introduces a novel joint control and communication design approach for systems with multiple controllers and sensors, including a Thompson sampling algorithm for adaptive channel access optimization.

Findings

ALOHA protocol parameters significantly impact control success.

Thompson sampling effectively adapts channel access, reducing regret.

Control performance depends on transmission success rates and protocol tuning.

Abstract

We develop a framework for communication-control co-design in a wireless networked control system with multiple geographically separated controllers and controlled systems, modeled via a Poisson point process. Each controlled system consists of an actuator, plant, and sensor. Controllers receive state estimates from sensors and design control inputs, which are sent to actuators over a shared wireless channel, causing interference. Our co-design includes control strategies at the controller based on sensor measurements and transmission acknowledgments from the actuators for both rested and restless systems - systems with and without state feedback, respectively. In the restless system, controllability depends on consecutive successful transmissions, while in the rested system, it depends on total successful transmissions. We use both classical and block ALOHA protocols for channel access, optimizing access based on sensor data and acknowledgments. A statistical analysis of control performance is followed by a Thompson sampling-based algorithm to optimize the ALOHA parameter, achieving sub-linear regret. We show how the ALOHA parameter influences control performance and transmission success in both system types.