| 1. |
- Alvarez, Ines, et al.
(author)
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Comparing Admission Control Architectures for Real-Time Ethernet
- 2020
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In: IEEE Access. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 2169-3536. ; 8, s. 136260-136260
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Journal article (peer-reviewed)abstract
- Industry 4.0 and Autonomous Driving are emerging resource-intensive distributed application domains that deal with open and evolving environments. These systems are subject to stringent resource, timing, and other non-functional constraints, as well as frequent reconfiguration. Thus, real-time behavior must not preclude operational flexibility. This combination is motivating ongoing efforts within the Time Sensitive Networking (TSN) standardization committee to define admission control mechanisms for Ethernet. Existing mechanisms in TSN, like those of AVB, its predecessor, follow a distributed architecture that favors scalability. Conversely, the new mechanisms envisaged for TSN (IEEE 802.1Qcc) follow a (partially) centralized architecture, favoring short reconfiguration latency. This paper shows the first quantitative comparison between distributed and centralized admission control architectures concerning reconfiguration latency. Here, we compare AVB against a dynamic real-time reconfigurable Ethernet technology with centralized management, namely HaRTES. Our experiments show a significantly lower latency using the centralized architecture. We also observe the dependence of the distributed architecture in the end nodes & x2019; performance and the benefit of having a protected channel for the admission control transactions.
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| 2. |
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| 3. |
- Alvarez Vadillo, Ines, et al.
(author)
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Implementing a First CNC for Scheduling and Configuring TSN Networks
- 2022
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In: IEEE International Conference on Emerging Technologies and Factory Automation, ETFA. - : Institute of Electrical and Electronics Engineers Inc.. - 9781665499965
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Conference paper (peer-reviewed)abstract
- Novel industrial applications are leading to important changes in industrial systems. One of the most important changes is the need for systems that are capable to adapt to changes in the environment or the system itself. Because of their nature many of these applications are distributed, and their network infrastructure is key to guarantee the correct operation of the overall system. Furthermore, in order for a distributed system to be able to adapt, its network must be flexible enough to support changes in the traffic during runtime. The Time-Sensitive Networking (TSN) Task Group has proposed a series of standards that aim at providing deterministic real-time communications over Ethernet. TSN also provides centralised online configuration and control architectures which enable the online configuration of the network. A key part in TSN's centralised architectures is the Centralised Network Configuration element (CNC). In this work we present a first implementation of a CNC capable of scheduling time-triggered traffic and deploying such configuration in the network using the Network Configuration (NETCONF) protocol. We also assess the correctness of our implementation using an industrial use case provided by Volvo Construction Equipment.
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| 4. |
- Aysan, Hüseyin, et al.
(author)
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Probabilistic Scheduling Guarantees in Distributed Real-Time Systems under Error Bursts
- 2012
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In: IEEE Symposium on Emerging Technologies and Factory Automation, ETFA 2012. - 9781467347372 ; , s. Article number: 6489644-
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Conference paper (other academic/artistic)abstract
- Networked embedded systems used in many real-time (RT) applications rely on dependable communication. Controller Area Network (CAN) has gained wider acceptance as a standard in a large number of applications, mostly due to its cost effectiveness, predictable performance, and its fault-tolerance capability. Research so far has focused on rather simplistic error models which assume only singleton errors separated by a minimum inter-arrival time. However, these systems are often subject to faults that manifest as error bursts of various lengths which have an adverse effect on the message response times that needs to be accounted for. Furthermore, an important factor to be considered in this context is the random nature of occurrences of faults and errors, which, if addressed in the traditional schedulability analysis by assuming a rigid worst case occurrence scenario, may lead to inaccurate results. In this paper we first present a stochastic fault and error model which has the capability of modeling error bursts in lieu of the commonly used simplistic error assumptions. We then present a methodology which enables the provision of appropriate probabilistic RT guarantees in distributed RT systems for the particular case of message scheduling on CAN under the assumed error assumptions
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| 5. |
- Bujosa Mateu, Daniel, et al.
(author)
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CSRP : An Enhanced Protocol for Consistent Reservation of Resources for AVB/TSN
- 2021
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In: IEEE Transactions on Industrial Informatics. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 1551-3203 .- 1941-0050. ; 17:5, s. 3640-3650
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Journal article (peer-reviewed)abstract
- The IEEE Audio Video Bridging (AVB) Task Group (TG) was created to provide Ethernet with soft real-time guarantees. Later on, the TG was renamed to Time-Sensitive Networking (TSN) and its scope broadened to support hard real-time and critical applications. The Stream Reservation Protocol (SRP) is a key work of the TGs as it allows reserving resources in the network, guaranteeing the required quality of service. AVB's SRP is based on a distributed architecture, whereas TSN's is based on centralized ones. The distributed version of SRP is supported and used in TSN. Nevertheless, it was not designed to provide properties that are important for critical applications. In this article, we model SRP using UPPAAL and we study the termination and consistency. We verify that SRP does not provide such properties. Furthermore, we propose an improved protocol called Consistent Stream Reservation Protocol (CSRP) and we formally verify its correctness using UPPAAL.
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| 6. |
- Bujosa Mateu, Daniel
(author)
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Enhancing TSN Adoption by Industry : Tools to Support Migrating Ethernet-based Legacy Networks into TSN
- 2023
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Licentiate thesis (other academic/artistic)abstract
- New technologies present opportunities and challenges for industries. One major challenge is the ease, or even feasibility, of its adoption. The Time-Sensitive Networking (TSN) standards offer a range of features relevant to various applications and are key for the transition to Industry 4.0. These features include deterministic zero-jitter, low-latency data transmission, transmission of traffic with various levels of time-criticality on the same network, fault tolerance mechanisms, and advanced network management allowing dynamic reconfiguration.This thesis aims to develop tools that enable the industry to adopt TSN easily and efficiently. Specifically, we create tools that facilitate the migration of legacy networks to TSN, enabling the preservation of most of the legacy systems and solutions while reducing costs and adoption time. Firstly, we introduce LETRA (Legacy Ethernet-based Traffic Mapping Tool), a tool for mapping Ethernet-based legacy traffic to the new TSN traffic classes. Secondly, we develop HERMES (Heuristic Multi-queue Scheduler), a heuristic Time-Triggered (TT) traffic scheduler that can meet the characteristics of legacy systems and provide quick results suitable for reconfiguration. Thirdly, we develop TALESS (TSN with Legacy End-Stations Synchronization), a mechanism to avoid adverse consequences caused by the lack of synchronization between legacy systems and TSN-based ones, as not all legacy systems need to support the TSN synchronization mechanisms. Finally, we improve Stream Reservation Protocol (SRP) to enhance Audio-Video Bridging (AVB) traffic configuration in terms of termination and consistency.
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| 7. |
- Bujosa Mateu, Daniel, et al.
(author)
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Improved Clock Synchronization in TSN Networks with Legacy End-Stations
- 2023
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Reports (other academic/artistic)abstract
- In order to enable the adoption of Time Sensitive Networking (TSN) by the industry and be more environmentally sustainable, it is necessary to develop tools to integrate legacy systems with TSN. In this paper, we propose a solution for the coexistence of different time domains from different legacy systems with their corresponding synchronization protocols in a single TSN network. To this end, we experimentally identified the effects of replacing the communications subsystem of a legacy Ethernet-based network with TSN in terms of synchronization. Based on the results, we propose a solution called TALESS (TSN with Legacy End-Stations Synchronization). TALESS is able to identify the drift between the TSN communications subsystem and the integrated legacy devices (end-stations) and modify the TSN schedule to adapt to the different time domains to avoid the effects of the lack of synchronization between them. We validate TALESS through both simulations and experiments on a prototype. Thereby we demonstrate that thanks to TALESS, legacy systems are able to synchronize through TSN and even improve features such as their reception jitter or their integrability with other legacy systems.
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| 8. |
- Bujosa Mateu, Daniel, et al.
(author)
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LETRA : Mapping Legacy Ethernet-Based Traffic into TSN Traffic Classes
- 2021
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In: 26th IEEE International Conference on Emerging Technologies and Factory Automation ETFA 2021. - Västerås, Sweden : IEEE. - 9781728129891
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Conference paper (peer-reviewed)abstract
- This paper proposes a method to efficiently map the legacy Ethernet-based traffic into Time Sensitive Networking (TSN) traffic classes considering different traffic characteristics. Traffic mapping is one of the essential steps for industries to gradually move towards TSN, which in turn significantly mitigates the management complexity of industrial communication systems. In this paper, we first identify the legacy Ethernet traffic characteristics and properties. Based on the legacy traffic characteristics we presented a mapping methodology to map them into different TSN traffic classes. We implemented the mapping method as a tool, named Legacy Ethernet-based Traffic Mapping Tool or LETRA, together with a TSN traffic scheduling and performed a set of evaluations on different synthetic networks. The results show that the proposed mapping method obtains up to 90% improvement in the schedulability ratio of the traffic compared to an intuitive mapping method on a multi-switch network architecture.
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| 9. |
- Bujosa Mateu, Daniel, et al.
(author)
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The Effects of Clock Synchronization in TSN Networks with Legacy End-Stations
- 2022
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Conference paper (peer-reviewed)abstract
- In this paper, we present our ongoing work on proposing solutions to integrate legacy end-stations into Time-Sensitive Network (TSN) communication systems where the legacy end-stations are synchronized via their legacy clock synchronization protocol. To this end, we experimentally identify the effects of lacking synchronization or partial synchronization in TSN networks. In the experiments we show the effects of clock synchronization in different scenarios on jitter and clock drifts. Based on the experiments, we propose preliminary solutions to overcome the identified effects.
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