Traffic-type Assignment for TSN-based Mixed-criticality Cyber-physical Systems

Abstract

This article focuses on mixed-criticality applications with functions that have different timing requirements, i.e., hard real-time (HRT), soft real-time (SRT), and functions that are not time-critical (NC). The applications are implemented on distributed cyber-physical systems that use IEEE Time-sensitive Networking (TSN). TSN is the product of an IEEE effort to bring deterministic real-time capabilities to IEEE 802.3 Ethernet. TSN supports the convergence of multiple traffic types, i.e., critical, real-time, and regular “best-effort” traffic within a single network: Time-triggered (TT), where the messages are transmitted based on static schedule tables, Audio-video Bridging (AVB), for dynamically scheduled messages with a guaranteed bandwidth and bounded delays, and Best Effort (BE), for which no timing guarantees are provided. The HRT messages have deadlines, whereas we capture the quality-of-service for the SRT messages using “utility functions.” Given the network topology, the set of application messages, including their routing, and the set of available AVB classes, we are interested in determining the traffic type of each message, such that all the HRT messages are schedulable and the total utility for the SRT messages is maximized. We propose a Tabu Search-based metaheuristic to solve this optimization problem. The proposed proof-of-concept tool has been evaluated using several benchmarks, including two realistic test cases.