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Switched real-time Ethernet in industrial applications - deadline partitioning
Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE).
Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE).ORCID iD: 0000-0002-6526-3931
2003 (English)In: APCC2003: the Ninth Asia-Pacific Conference on Communications : in conjunction with 6th Malaysia International Conference on Communications (MICC03) : 21-24 September, 2003, City Bayview Hotel, Penang, Malaysia / [ed] Mahamod Ismail et al., Piscataway, N.J.: IEEE, 2003, p. 76-81, article id 1274315Conference paper, Published paper (Refereed)
Abstract [en]

This paper presents work on a switched Ethernet network extended to allow for periodic real-time traffic, using earliest deadline first (EDF) scheduling. A scheme of asymmetrically dividing deadlines of real-time channels between the in and outgoing links to/from the switch is proposed (ADPS). The scheme is compared with the simpler approach of dividing the deadlines in two (SDPS). The results of several software simulations of setting up RT channels over a full-duplex switched Ethernet network are presented. The simulations show that the ADPS performs better than the SDPS when master-slave communication is assumed over the network.

Place, publisher, year, edition, pages
Piscataway, N.J.: IEEE, 2003. p. 76-81, article id 1274315
Keywords [en]
Local area networks, Scheduling, Telecommunication channels, Telecommunication switching, Telecommunication traffic, Transport protocols
National Category
Communication Systems
Identifiers
URN: urn:nbn:se:hh:diva-396DOI: 10.1109/APCC.2003.1274315ISI: 000189415600018Scopus ID: 2-s2.0-84947305578Local ID: 2082/720ISBN: 0-7803-8114-9 (print)OAI: oai:DiVA.org:hh-396DiVA, id: diva2:237575
Conference
9th IEEE Asia-Pacific Conference on Communications, APCC 2003, in conjunction with 6th Malaysia International Conference on Communications, MICC 2003, City Bayview Hotel, Penang, Malaysia, 21-24 September, 2003
Note

©2003 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.

Available from: 2007-01-12 Created: 2007-01-12 Last updated: 2018-03-23Bibliographically approved
In thesis
1. Enhancing the Performance of Distributed Real-time Systems
Open this publication in new window or tab >>Enhancing the Performance of Distributed Real-time Systems
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Advanced embedded systems can consist of many sensors, actuators and processors that are deployed on one or several boards, while having a demand of interacting with each other and sharing resources. Communication between different components usually has strict timing constraints. There is thus a strong need to provide solutions for time critical communication. This thesis focuses on both the support of real-time services over standard switched Ethernet networks and the improvement of systems' real-time characteristics, such as reducing delay and jitter in processors and on communication links.

Switched Ethernet has been chosen in this work because of its major advantages in industry; it supports higher bit-rates than most other current LAN (Local Area Network) technologies, including field buses, still at a low cost. We propose using a star network topology with a single Ethernet switch. Each node is connected to a separate port of the switch via a full-duplex link, thereby eliminating collisions. A solid real-time communication protocol for switched Ethernet networks is proposed in the thesis, including a real-time layer between the Ethernet layer and the TCP/IP suite. The network has the capability of supporting both real-time and non real-time traffic and assuring adaptation to the surrounding protocol standards.

Most embedded systems work in a dynamic environment, where the precise behavior of the network traffic can usually not be predicted. To support real-time services, we have chosen the Earliest Deadline scheduling algorithm (EDF) because of its optimality, high efficiency and suitability for being used in adaptive schemes. To be able to increase the amount of guaranteed real-time traffic, the notion of Asymmetric Deadline Partitioning Scheme (ADPS) is introduced. ADPS allows distribution of the end-to-end deadline of a message, sent from any source node in the network to any destination node via the switch, into two sub-deadlines, one for each hop according to the load of the physical link that it must traverse.

For the EDF scheduling algorithm, the feasibility test is one of the most important techniques that provides us with information about whether or not the real-time traffic can be guaranteed by the network. With the same computational complexity as the feasibility test, a method has been developed to compute the minimum EDF-feasible deadline for a real-time task. The importance of this method in real-time applications lies in that it can be effectively used to reduce the response times of specific control activities or limit their input-output jitter. To allow more flexibility in the control of delay and jitter in real-time systems, a general approach for reducing task deadlines according to the requirements of individual tasks has been developed. The method allows the user to specify a deadline reduction factor for each task in order to better exploit the available slack according to the tasks' actual requirements.

Place, publisher, year, edition, pages
Göteborg: Chalmers university of technology, 2007. p. 156
Series
Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie, ISSN 0346-718X ; 2599
Keywords
Switched Ethernet, Real-Time Communication, EDF scheduling, Reducation of delay and jitter
National Category
Computer Sciences
Identifiers
urn:nbn:se:hh:diva-1986 (URN)2082/2381 (Local ID)978-91-7291-918-1 (ISBN)2082/2381 (Archive number)2082/2381 (OAI)
Public defence
2007-05-14, Wigforssalen, Halmstad, 10:15 (English)
Opponent
Supervisors
Note

Ingår även i serien: Technical report. D / Department of Computer Science and Engineering, Chalmers University of Technology, 1653-1787 ; 28

Available from: 2008-09-29 Created: 2008-09-29 Last updated: 2018-03-23Bibliographically approved
2. Switched Real-Time Ethernet for Industrial Applications
Open this publication in new window or tab >>Switched Real-Time Ethernet for Industrial Applications
2003 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The research reported in this thesis has been focused on developing and analyzing how to support real-time traffic over a switched Ethernet network without any hardware or protocol modifications. The work has resulted in a proposed systems model, supporting both real-time and non real-time traffic. Currently this model is intended for a one-switch network, with no shared media. All added traffic handling to support real-time communication is positioned in a thin layer (RT layer) added between the Ethernet layer and the TCP/IP suite. This assures adaptation to the surrounding protocol standards. The RT layer manages traffic on the basis of virtual connections, denoted as RT channels, as well as packet level scheduling. RT channels are created between end-nodes prior to any occurrence of real-time traffic. Asymmetric deadline partitioning between the links of the RT channels is also proposed, in order to increase the number of possible RT channels.

Place, publisher, year, edition, pages
Göteborg: Chalmers tekniska högskola, 2003. p. 16
Series
Technical report L, ISSN 1651-4963 ; 20
Keywords
Switched Ethernet, Real-time communication, EDF scheduling, Industrial networks
National Category
Communication Systems
Identifiers
urn:nbn:se:hh:diva-599 (URN)2082/941 (Local ID)2082/941 (Archive number)2082/941 (OAI)
Presentation
2003-05-27, Wigforssalen, Kristian IV:s väg, Halmstad, 13:15 (English)
Supervisors
Available from: 2007-04-10 Created: 2007-04-10 Last updated: 2018-03-23Bibliographically approved

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