# Optimal Scheduling for Discounted Age Penalty Minimization in Multi-Loop Networked Control

## TL;DR

This paper introduces an AoI-based wireless scheduling policy for multi-loop networked control systems that minimizes control error over an infinite horizon, outperforming existing policies.

## Contribution

It is the first to propose an AoI-based scheduling policy specifically designed to minimize control error in multi-loop NCS over an infinite horizon.

## Key findings

- The proposed scheduler outperforms existing policies in simulations.
- A stationary scheduling policy is derived from the MDP model.
- The relation between control error and AoI is established.

## Abstract

Age-of-information (AoI) is a metric quantifying information freshness at the receiver. Since AoI combines packet generation frequency, packet loss, and delay into a single metric, it has received a lot of research attention as an interface between communication network and application. In this work, we apply AoI to the problem of wireless scheduling for multi-loop networked control systems (NCS), i.e., feedback control loops closed over a shared wireless network. We model the scheduling problem as a Markov decision process (MDP) with AoI as its observable states and derive a relation of control system error and AoI. We further derive a stationary scheduling policy to minimize control error over an infinite horizon. We show that our scheduler outperforms the state-of-the-art scheduling policies for NCS. To the best of our knowledge, this is the first work proposing an AoI-based wireless scheduling policy that minimizes the control error over an infinite horizon for multi-loop NCS.