The design of large real-time systems: the time-triggered approach

Kopetz, Hermann; Braun, Markus Sebastian; Ebner, Christian; Krüger, Andreas; Millinger, Dietmar; Nossal, Roman; Schedl, Anton

doi:10.1109/real.1995.495208

Cited by 13 publications

(5 citation statements)

References 9 publications

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“…The starting point is the topology of a network implemented by MallorcaWifi in Platja de Palma, a wide tree topology that provides a free wireless connection in a large and very populated touristic area. This network has received much attention because of its size and high throughput 2 .…”

Section: Case Studymentioning

confidence: 99%

“…The time-triggered (TT) communication paradigm, originated with the Time-Triggered Protocol (TTP) [1], has been advocated for networks that require low transmission latency and high reliability. These requirements are standard in many real-time distributed embedded systems, particularly in areas like automation, automotive and aerospace [2]. Several adaptations of the TT paradigm for Fieldbus communication have been implemented, including SAFEbus [3], TTCAN [4] and FlexRay [5].…”

Section: Introductionmentioning

confidence: 99%

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Methods for Large-Scale Time-Triggered Network Scheduling

Pozo¹,

Rodríguez-Navas²,

Hansson³

2019

Preprint

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Future cyber-physical systems may extend over broad geographical areas, like cities or regions, thus requiring the deployment of large real-time networks. A strategy to guarantee predictable communication over such networks is to synthesize an offline time-triggered communication schedule. However, this synthesis problem is computationally hard (NP-complete), and existing approaches do not scale satisfactorily to the required network sizes. This article presents a segmented offline synthesis method which substantially reduces this limitation, being able to generate time-triggered schedules for large hybrid (wired and wireless) networks. We also present a series of algorithms and optimizations that increase the performance and compactness of the obtained schedules while solving some of the problems inherent to segmented approaches. We evaluate our approach on a set of realistic large-size multi-hop networks, significantly larger than those considered in the existing literature. The results show that our segmentation reduces the synthesis time up to two orders of magnitude.

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Section: Case Studymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Methods for Large-Scale Time-Triggered Network Scheduling

Pozo¹,

Rodríguez-Navas²,

Hansson³

2019

Preprint

View full text Add to dashboard Cite

show abstract

“…The time-triggered (TT) communication paradigm, which originated with the time-triggered protocol (TTP) [1], has been advocated fornetworks that require low transmission latency and high reliability. These requirements are standard in many real-time distributed embedded systems, particularly in areas like automation, automotive and aerospace [2]. Several adaptations of the TT paradigm for Fieldbus communication have been implemented, including SAFEbus [3], TTCAN [4] and FlexRay [5].…”

Section: Introductionmentioning

confidence: 99%

Methods for Large-Scale Time-Triggered Network Scheduling

2019

View full text Add to dashboard Cite

Future cyber–physical systems may extend over broad geographical areas, like cities or regions, thus, requiring the deployment of large real-time networks. A strategy to guarantee predictable communication over such networks is to synthesize an offline time-triggered communication schedule. However, this synthesis problem is computationally hard (NP-complete), and existing approaches do not scale satisfactorily to the required network sizes. This article presents a segmented offline synthesis method which substantially reduces this limitation, being able to generate time-triggered schedules for large hybrid (wired and wireless) networks. We also present a series of algorithms and optimizations that increase the performance and compactness of the obtained schedules while solving some of the problems inherent to segmented approaches. We evaluate our approach on a set of realistic large-size multi-hop networks, significantly larger than those considered in the existing literature. The results show that our segmentation reduces the synthesis time by up to two orders of magnitude.

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“…satisfaction of hard message deadlines, the socalled Time-Triggered (TT) scheduling of messages has been advocated [27]. TT scheduling assumes the existence of a common notion of time throughout the system, usually implemented with some kind of clock synchronization protocol, therefore allowing a globally consistent definition of time slots [19]. The switches follow a schedule that prescribes which message is sent through each link for every time slot.…”

Section: Introductionmentioning

confidence: 99%

Synthesizing time-triggered schedules for switched networks with faulty links

Avni

Guha

Rodríguez-Navas

2016

Proceedings of the 13th International Conference on Embedded Software

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Time-triggered (TT) switched networks are a deterministic communication infrastructure used by real-time distributed embedded systems. These networks rely on the notion of globally discretized time (i.e. time slots) and a static TT schedule that prescribes which message is sent through which link at every time slot, such that all messages reach their destination before a global timeout. These schedules are generated offline, assuming a static network with fault-free links, and entrusting all error-handling functions to the end user. Assuming the network is static is an over-optimistic view, and indeed links tend to fail in practice. We study synthesis of TT schedules on a network in which links fail over time and we assume the switches run a very simple error-recovery protocol once they detect a crashed link. We address the problem of finding a pk, qresistant schedule; namely, one that, assuming the switches run a fixed error-recovery protocol, guarantees that the number of messages that arrive at their destination by the timeout is at least , no matter what sequence of at most k links fail. Thus, we maintain the simplicity of the switches while giving a guarantee on the number of messages that meet the timeout. We show how a pk, q-resistant schedule can be obtained using a CEGAR-like approach: find a schedule, decide whether it is pk, q-resistant, and if it is not, use the witnessing fault sequence to generate a constraint that is added to the program. The newly added constraint disallows the schedule to be regenerated in a future iteration while also eliminating several other schedules that are not pk, q-resistant. We illustrate the applicability of our approach using an SMT-based implementation.

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The design of large real-time systems: the time-triggered approach

Cited by 13 publications

References 9 publications

Methods for Large-Scale Time-Triggered Network Scheduling

Methods for Large-Scale Time-Triggered Network Scheduling

Methods for Large-Scale Time-Triggered Network Scheduling

Synthesizing time-triggered schedules for switched networks with faulty links

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