Search

The set of IEEE Time-Sensitive Networking (TSN) standards is an emerging candidate for backbone communication in modern applications of real-time distributed embedded systems. TSN provides various traffic shaping mechanisms that aim at managing the timing requirements of traffic. Emerging applications of these systems, particularly in the automotive domain, often run complex distributed software that requires low-latency and high-bandwidth communication across multiple onboard electronic control units. Using TSN in these systems introduces multiple challenges. Specifically, the developers of these systems face a lack of development techniques and tools, as TSN standards only offer general recommendations for the use of its features and mechanisms. There is an urgent need for development techniques, tools, and methods to assist the developers in effectively leveraging the features outlined in TSN standards. In this thesis, we identify and address several challenges encountered in the development of TSN-based distributed embedded systems, particularly focusing on the stages of system and software modeling, network configuration, and timing analysis. The overall goal of this thesis is to support the development of these systems in the aforementioned stages while considering the Quality of Service (QoS) requirements of all traffic classes in TSN. We present techniques to facilitate the system and software modeling of TSN-based distributed embedded systems. These techniques enable performing timing analysis in the early stages of system and software development. In the stage of network configuration, we propose techniques for managing the configuration complexity and supporting the automatic configuration of mechanisms in TSN. The proposed configuration techniques consider achieving acceptable QoS in various traffic classes. In the stage of timing analysis, we address the challenges of incorporating various TSN traffic classes and mechanisms by extending the existing tim, IEEE Time-Sensitive Networking (TSN) är en framväxande kommunikationsteknik för moderna tillämpningar inom distribuerade inbyggda realtidssystem. TSN definerar olika mekanismer för trafikomformning som syftar till att ge flexibilitet i hur fördröjningar och bandbredd fördelas mellan olika användare. Nya tillämpningar av distribuerade inbyggda system i realtid har ofta mycket komplex distribuerad programvara som kräver kommunikation med låg latens och hög bandbredd över flera enheter (ECU I automotiv system). Att anpassa sig till TSN för att utveckla sådana system innebär många utmaningar. Dessutom finns det en brist på stödtekniker för utvecklare eftersom TSN-standarder endast ger generaliserade rekommendationer för tillämpningen av dess mekanismer. Därför finns det ett behov av tekniker och metoder för att stödja utvecklare att använda tillgängliga funktioner i TSN-standarderna. I den här avhandlingen angriper vi några av utmaningarna i utvecklingsstadierna av TSN-baserade distribuerade inbyggda system som är modellering, konfiguration av nätverk och tidsanalys. Målet med avhandlingen är att stödja utvecklingen av TSN-baserade distribuerade inbyggda system i dessastadier, samtidigt som man tar hänsyn till Quality of Service (QoS) krav inom alla trafikklasser i TSN. Vi tillhandahåller tekniker för att underlätta system- och mjukvarumodellering av TSN-baserade distribuerade inbyggda system som ger ett verktyg för utvecklare att designa sina system i tidiga stadier av systemutveckling. Inom konfiguration av nätverk föreslår vi tekniker för att hantera komplexiteten och den automatiska konfigurationen av TSN-formningsmekanismer. Under tiden tar vi hänsyn till att nå en acceptabel QoS i olika trafikklasser. Inom tidsanalysen tar vi itu med utmaningarna med att införliva olika TSN-trafikklasser och mekanismer genom att utöka de befintliga tidsanalysmetoderna. Genom de tre bidragna tillvägagångssätten underlättar våra resultat processen att utveckla TSN-baserade distribue

In this paper, we present a bandwidth reservation analysis for Audio-Video Bridging (AVB) traffic in the Time-Sensitive Networking (TSN) standards. The proposed analysis is based on the existing worst-case response-time analysis and can be used to calculate the minimum required bandwidth for guaranteeing the schedulability of messages in AVB classes. The proposed analysis allocates per-link bandwidth to AVB traffic that is sufficient to ensure its schedulability when a combination of the Credit-Based Shaper and Time-Aware Shaper mechanisms are used. We evaluate the proposed analysis using an automotive industrial use case. We evaluate the schedulability of AVB traffic by comparing the proposed analysis with the utilization-based bandwidth reservation as recommended by the TSN standards.

In this paper, we present an end-to-end timing model to capture timing information from software architectures of distributed embedded systems that use network communication based on the Time-Sensitive Networking (TSN) standards. Such a model is required as an input to perform end-to-end timing analysis of these systems. Furthermore, we present a methodology that aims at automated extraction of instances of the end-to-end timing model from component-based software architectures of the systems and the TSN network configurations. As a proof of concept, we implement the proposed end-to-end timing model and the extraction methodology in the Rubus Component Model (RCM) and its tool chain Rubus-ICE that are used in the vehicle industry. We demonstrate the usability of the proposed model and methodology by modeling a vehicular industrial use case and performing its timing analysis.

Timing requirements in predictable distributed embedded software systems can be verified by performing endto-end timing analysis. To perform such an analysis, end-toend timing information should be extracted form the Software Architectures (SWA) of these systems. In this paper, we first present a comprehensive end-to-end timing model of distributed embedded software systems that use Time-Sensitive Networking (TSN) for network communication. This is the first timing model that captures comprehensive timing information of TSN as part of the end-to-end timing model. We then present a systematic automated method to extract the end-to-end timing model from the SWA of distributed embedded systems. As a proof of concept, we implement the timing model and extraction method in an industrial component model, namely the Rubus Component Model (RCM), and in its tool chain. We evaluate the proposed method and demonstrate its usability on an industrial use-case from the vehicular domain.

This paper presents a schedulability analysis for the Best-Effort (BE) traffic class within Time-Sensitive Networking (TSN) networks. The presented analysis considers several features in the TSN standards, including the Credit-Based Shaper (CBS), the Time-Aware Shaper (TAS), and the frame preemption. Although the BE class in TSN is primarily used for the traffic with no strict timing requirements, some industrial applications prefer to utilize this class for the non-hard real-time traffic instead of classes that use the CBS. The reason mainly lies in the fact that the complexity of TSN configuration becomes significantly high when the time-triggered traffic via the TAS and other classes via the CBS are used altogether. We demonstrate the applicability of the presented analysis on a vehicular application use case. We show that a network designer can get information on the schedulability of the BE traffic, based on which the network configuration can be further refined with respect to the application requirements.

The IEEE Time-Sensitive Networking (TSN) standards' amendment 802.1Qbv provides real-time guarantees for Scheduled Traffic (ST) streams by the Time Aware Shaper (TAS) mechanism. In this paper, we develop offline schedule optimization objective functions to configure the TAS for ST streams, which can be effective to achieve a high Quality of Service (QoS) of lower priority Best-Effort (BE) traffic. This becomes useful if real-time streams from legacy protocols are configured to be carried by the BE class or if the BE class is used for value-added (but non-critical) services. We present three alternative objective functions, namely Maximization, Sparse and Evenly Sparse, followed by a set of constraints on ST streams. Based on simulated stream traces in OMNeT++/INET TSN NeSTiNg simulator, we compare our proposed schemes with a most commonly applied objective function in terms of overall maximum end-to-end delay and deadline misses of BE streams. The results confirm that changing the schedule synthesis objective to our proposed schemes ensures timely delivery and lower end-to-end delays in BE streams., DESTINE: Developing Predictable Vehicle Software Utilizing Time Sensitive Networking

Designing and simulating large networks, based on the Time-Sensitive Networking (TSN) standards, require complex and demanding configuration at the design and pre-simulation phases. The existing configuration and simulation frameworks support only the manual configuration of TSN networks. This hampers the applicability of these frameworks to large-sized TSN networks, especially in complex industrial embedded system applications. This paper proposes a modular framework to automate offline scheduling in TSN networks to facilitate the design time and pre-simulation automated network configurations as well as interpretation of the simulations. To demonstrate and evaluate the applicability of the proposed framework, a large TSN network is automatically configured and its performance is evaluated by measuring end-to-end delays of time-critical flows in a state-of-the-art simulation framework, namely NeSTiNg., DESTINE: Developing Predictable Vehicle Software Utilizing Time Sensitive Networking

This paper investigates the effects of various parameters of high priority traffic classes on the Best Effort (BE) traffic in the networks based on the IEEE Time Sensitive Networking (TSN) standards. In this regard, the paper discusses ongoing work and presents preliminary results using a TSN simulator. The results indicate that several parameters of the high priority traffic such as periods, offsets and preemption modes can have a significant impact on the quality of service (e.g., guaranteed message delivery and message delays) of the BE traffic.

XPRES - Excellence in Production Research, DESTINE: Developing Predictable Vehicle Software Utilizing Time Sensitive Networking