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  • 51.
    Forsberg, Håkan
    et al.
    Department of Computer Engineering Chalmers University of Technology Göteborg, Sweden.
    Jonsson, Magnus
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE).
    Svensson, Bertil
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE).
    Embedded Signal Processing Using Free-Space Optical Hypercube Interconnects2003In: Optical Networks Magazine, ISSN 1572-8161, Vol. 4, no 4, p. 35-49Article in journal (Refereed)
    Abstract [en]

    The speed and complexity of integrated circuits are increasing rapidly. For instance, today's mainstream processors have already surpassed gigahertz global clock frequencies on-chip. As a consequence, many algorithms proposed for applications in embedded signal-processing (ESP) systems, e.g. radar and sonar systems, can be implemented with a reasonable number (less than 1000) of processors, at least in terms of computational power. An extreme inter-processor network is required, however, to completely implement those algorithms. The demands are such that completely new interconnection architectures must be considered.

    In the search for new architectures, developers of parallel computer systems can actually take advantage of optical interconnects. The main reason for introducing optics from a system point of view is the strength in using benefits that enable new architecture concepts, e.g. free-space propagation and easy fan-out, together with benefits that can actually be exploited by simply replacing the electrical links with optical ones without changing the architecture, e.g. high bandwidth and complete galvanic isolation.

    In this paper, we propose a system suitable for embedded signal processing with extreme performance demands. The system consists of several computational modules that work independently and send data simultaneously in order to achieve high throughput. Each computational module is composed of multiple processors connected in a hypercube topology to meet scalability and high bisection bandwidth requirements. Free-space optical interconnects and planar packaging technology make it possible to arrange the hypercubes as planes with an associated three-dimensional communications space and to take advantage of many optical properties. For instance, optical fan-out reduces hardware cost. Altogether, this makes the system capable of meeting high performance demands in, for example, massively parallel signal processing. One 64-channel airborne radar system with nine computational modules and a sustained computational speed of more than 1.6 Tera floating point operations per second (TFLOPS) is presented. The effective inter-module bandwidth in this configuration is 1 024 Gbit/s.

  • 52.
    Forsberg, Håkan
    et al.
    Department of Computer Engineering, Chalmers University of Technology, Göteborg, Sweden.
    Jonsson, Magnus
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Svensson, Bertil
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Key Issues in Implementing an Optoelectronic Planar Free-space Architecture for Signal Processing Applications2003In: IASTED International Multi-Conference on Applied Informatics, IASTED/ACTA Press , 2003, p. 621-629Conference paper (Other (popular science, discussion, etc.))
    Abstract [en]

    In this paper, we deal with the key issues in implementing an optoelectronic architecture suitable for embedded signal processing. The architecture is based on a system concept where free-space optical interconnects and planar packaging technologies make it possible to merge complicated and new parallel computer architectures into planes and to take advantage of many properties of optics. For instance, optical fan-out reduces the hardware cost as well as the all-to-all broadcast time. It is also possible to meet scalability and high bisection bandwidth requirements. The main results show that it is possible to build a 6D hypercube using planar optical substrates.

  • 53.
    Forsberg, Håkan
    et al.
    Department of Computer Engineering, Chalmers University of Technology, Göteborg, Sweden.
    Jonsson, Magnus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Svensson, Bertil
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Opportunities for Optical Planar Interconnection Technology in Terabit Switches2003In: Proceedings of the IASTED International Conference on Wireless and Optical Communications, July 2-4, 2003, Banff, Canada / [ed] Lambertus Hesselink, Anaheim; Calgary: ACTA Press , 2003, p. 155-164Conference paper (Refereed)
    Abstract [en]

    To keep up with the explosive growth of world-wide network traffic, large-capacity switches, with switching capacities in excess of several terabits per second, are becoming an essential part of the future. To realize such switches, new architecture concepts must be considered. In this paper, we discuss a technology for terabit switches that combines the advantage of using optical communication in all three spatial dimensions and the benefits of using surface mounted optoelectronic as well as electronic chips. We present three different types of packet-based switch fabrics, all based on the optical planar interconnection technology. We then discuss these in terms of capacity, scalability, and physical size. All three implementations have a single switch plane cross sectional bandwidth exceeding 5 Tbps.

  • 54.
    Forsberg, Håkan
    et al.
    Chalmers University of Technology, Göteborg, Sweden.
    Jonsson, Magnus
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Svensson, Bertil
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Optical interconnect architectures in signal processing systems and terabit communication equipment2001In: Optik i Sverige 2001: Optics in Sweden 2001: Summeries of contributions to the conference of the Swedish Optical Society held in Stockholm 8 November 2001 / [ed] Ulf Olin and Klaus Biedermann, Stockholm: Swedish Optical Society , 2001Conference paper (Refereed)
    Abstract [en]

    N/A

  • 55.
    Forsberg, Håkan
    et al.
    Department of Computer Engineering, Chalmers University of Technology, Göteborg, Sweden.
    Svensson, Bertil
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE).
    Åhlander, Anders
    Airborne Radar Division, Ericsson Microwave Systems, Mölndal, Sweden.
    Jonsson, Magnus
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE).
    Radar signal processing using pipelined optical hypercube interconnects2001In: Proceedings of the 15th International Parallel and Distributed Processing Symposium: IPDPS 2001 : abstracts and CD-ROM, Los Alamitos, California: IEEE Computer Society Press , 2001, p. 2043-2052, article id 925201Conference paper (Refereed)
    Abstract [en]

    In this paper, we consider the mapping of two radar algorithms on a new scalable hardware architecture. The architecture consists of several computational modules that work independently and send data simultaneously in order to achieve high throughput. Each computational module is composed of multiple processors connected in a hypercube topology to meet scalability and high bisection bandwidth requirements. Free-space optical interconnects and planar packaging technology make it possible to transform the hypercubes into planes. Optical fan-out reduces the number of optical transmitters and thus the hardware cost. Two example systems are analyzed and mapped onto the architecture. One 64-channel airborne radar system with a sustained computational load of more than 1.6 TFLOPS, and one ground-based 128-channel radar system with extreme inter-processor communication demands.

  • 56.
    Ganjalizadeh, Milad
    et al.
    Halmstad University, School of Information Technology.
    Jonsson, Magnus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Kunert, Kristina
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Reliability Enhancement for Hard Real-Time Communication in Industrial Packet-Switched Networks2014In: Multiple Access Communications: 7th International Workshop, MACOM 2014, Halmstad, Sweden, August 27-28, 2014. Proceedings / [ed] Magnus Jonsson, Alexey Vinel, Boris Bellalta & Evgeny Belyaev, Cham: Springer, 2014, Vol. 8715, p. 59-74Conference paper (Refereed)
    Abstract [en]

    Large industrial control and automation applications require reliable communication with strict timing constraints between distributed communication equipment. Packet-switched networks are widely used as a high-speed, deterministic, and low-cost solution to handle these types of distributed real-time systems. Although research on guaranteeing timing requirements in packet-switched networks has been done, communication reliability is still an open problem for hard real-time applications. In this paper, a framework for enhancing the reliability in multihop packet-switched networks is presented. Moreover, an admission control mechanism using a real-time analysis is suggested to provide deadline guarantees for hard real-time traffic. The performance evaluation of the proposed solution shows a possible enhancement of the message error rate by several orders of magnitude while the decrease in network utilization stays at a reasonable level. © Springer International Publishing Switzerland 2014

  • 57.
    Garcia, Alejandro
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Johansson, Lisbeth
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Jonsson, Magnus
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Weckstén, Mattias
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Guaranteed periodic real-time communication over wormhole switched networks2000In: Parallel and distributed computing systems: proceedings of the ISCA 13th international conference, Las Vegas, Nevada, USA, August 8 - 10, 2000 / [ed] Ghulam Chaudhry; Edwin Sha, Raleigh, NC: INTERNATIONAL SOCIETY COMPUTERS & THEIR APPLICATIONS (ISCA) , 2000, p. 632-639Conference paper (Refereed)
    Abstract [en]

    In this paper, we investigate how to efficiently implement TDMA (Time Division Multiple Access) on a wormhole switched network using a pure software solution in the end nodes. Transmission is conflict free on the time-slot level and hence deadlock free. On the sub- slot level, however, conflicts are possible when using early sending, a method we propose in order to reduce latency while still not hazarding the TDMA schedule. We propose a complete system to offer services for dynamic establishment of guaranteed periodic real-time virtual channels. Two different clock synchronization approaches for integration into the TDMA system are discussed. Implementation and experimental studies have been done on a cluster of PCs connected by a Myrinet network. Also, a case study with a radar signal processing application is presented to show the usability. A best-case reduction of the latency of up to 37 percent for 640 Byte messages by using early sending in Myrinet is shown in the case study. Source routed wormhole switching networks are assumed in the work but the results are applicable on some other categories of switched networks too.

  • 58.
    Hilt, Benoît
    et al.
    University of Haute Alsace, Mulhouse, Colmar, France.
    Berbineau, MarionFrench Institute of Science and Technology, Spatial Planning, Development, and Networks, Villeneuve d'Ascq, France.Vinel, AlexeyHalmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).Jonsson, MagnusHalmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).Pirovano, AlainÉcole Nationale de l’Aviation Civile, Toulouse, France.
    Communication Technologies for Vehicles: 14th International Workshop, Nets4Cars/Nets4Trains/Nets4Aircraft 2019, Colmar, France, May 16–17, 2019, Proceedings2019Conference proceedings (editor) (Refereed)
  • 59.
    Hoang, Hoai
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Buttazzo, Giorgio
    Real-Time Systems Laboratory Scuola Superiore Sant’Anna Pisa, Italy.
    Jonsson, Magnus
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Reducing delay and jitter in software control systems2007Conference paper (Refereed)
    Abstract [en]

    Software control systems may be subject to high interference caused by concurrency and resource sharing. Reducing delay and jitter in such systems is crucial for guaranteeing high performance and predictability. In this paper, we present a general approach for reducing delay and jitter by acting on task relative deadlines. The method allows the user to specify a deadline reduction factor for each task to better exploit the available slack according to specific jitter sensitivity. Experimental results confirm the effectiveness and the generality of the proposed approach with respect to other methods available in the literature.

  • 60.
    Hoang, Hoai
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Buttazzo, Giorgio
    Real-Time Systems Laboratory Scuola Superiore Sant’Anna Pisa, Italy.
    Jonsson, Magnus
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Karlsson, Stefan
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Computing the minimum EDF feasible deadline in periodic systems2006In: 12th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications, 2006. Proceedings, Los Alamitos, Calif.: IEEE Press, 2006, p. 125-134Conference paper (Refereed)
    Abstract [en]

    In most real-time applications, deadlines are artifices that need to be enforced to meet different performance requirements. For example, in periodic task sets, jitter requirements can be met by assigning suitable relative deadlines and guaranteeing the feasibility of the schedule. This paper presents a method (called minD) for calculating the minimum EDF-feasible deadline of a real-time task. More precisely, given a set of periodic tasks with hard real-time requirements, which is feasible under EDF, the proposed algorithm allows computing the shortest deadline that can be assigned to an arbitrary task in the set, or to a new incoming task (periodic or aperiodic), still preserving the EDF feasibility of the new task set. The algorithm has a pseudo polynomial complexity and handles arbitrary relative deadlines, which can be less than, equal to, or greater than periods.

  • 61.
    Hoang, Hoai
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Jonsson, Magnus
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Real-time communication for industrial embedded systems using switched Ethernet2006In: ARTES - A network for Real-Time research and graduate Education in Sweden 1997-2006 / [ed] Hans Hansson, Uppsala: Uppsala universitet, 2006, p. 417-427Chapter in book (Refereed)
    Abstract [en]

    This paper focuses on developing and analyzing support for real-time traffic over a switched Ethernet network without any hardware or protocol modifi- cations. Network architecture with full-duplex switched Ethernet and endnodes has been assumed. The switch and the end nodes control the real-time traffic with Earliest Deadline First (EDF) scheduling on the frame level. No modification to the Ethernet standard is needed in the network that supports both real-time and non-real -time TCP/IP communication. The switch is responsible for admission control where feasibility analysis is made for each link between source and destination. 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. The comparison of two deadline-partitioning schemes, to partition the delay budget over the links for a path, is also presented. While SDPS (Symmetric Deadline Partitioning Scheme) is straightforward to implement, ADPS (Asymmetric Deadline Partitioning Scheme) is devised in order to have a more flexiblefeasibilitytest. ADPSshows promises in removing bottlenecks from links, especially when a master-slave communication is considered as the traffic pattern, and ADPS proves to be a better choice than SDPS.

  • 62.
    Hoang, Hoai
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE).
    Jonsson, Magnus
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE).
    Switched Real-Time Ethernet in Industrial Applications - Asymmetric Deadline Partitioning Scheme2003In: Proc. of the 2nd International Workshop on Real-Time LANs in the Internet Age (RTLIA'2003) in conjunction with the 15th Euromicro Conference on Real-Time Systems, Porto, Portugal, July 1, 2003, 2003, p. 4-Conference 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 result of the simulations of setting up RT channels over a full-duplex switched Ethernet network is presented. The simulations show that the ADPS performs well when master-slave communication is assumed over the network. thin layer is needed between the Ethernet protocols and the TCP/IP suite in the end-stations. The switch is responsible for admission control, while both end-stations and the switch have EDF (Earliest Deadline First) scheduling (7). The deadlines of messages over the network are end-to-end based, insofar as it is the maximum time to deliver, from the release time in the source node, to the arrival in the destination. In this paper, we assume a single switch, with one node connected to each physical port. The messages originating from the source do therefore traverse two links, and we need to provide guarantees for the time to deliver over both links. We approach this problem by dividing the end-to- end deadline into two, one for the source to the switch, and one from the switch to the destination. The deadline can be partitioned in a number of ways. The method we choose affects the system. The paper is concerned with analyzing the partitioning of deadlines, and to propose a way that is more suitable for master slave communication, which is a common demand in industrial applications. The results, and indeed the method in its current form, do not refer to a mixed topology. The network topology is confined to a star, with one centralized switch connected to one node on each physical port. A full-duplex network is assumed. The rest of the paper is organized as follows. The network architecture is presented in Section 2. In Section 3, a feasibility analysis is introduced. In section 3, the Asymmetric Deadline Partitioning Scheme (ADPS) with the simulation results are presented.

  • 63.
    Hoang, Hoai
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE).
    Jonsson, Magnus
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE).
    Switched real-time Ethernet in industrial applications - deadline partitioning2003In: 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 (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.

  • 64.
    Hoang, Hoai
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Jonsson, Magnus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Hagström, Ulrik
    Kallerdahl, Anders
    Switched real-time Ethernet with earliest deadline first scheduling - protocols and traffic handling2002In: Proceedings: International Parallel and Distributed Processing Symposium : April 15-19, 2002, Ft. Lauderdale, Florida, USA, Los Alamitos, Calif.: IEEE Computer Society , 2002, p. 94-99, article id 1016477Conference paper (Refereed)
    Abstract [en]

    There is a strong interest of using the cheap and simple Ethernet technology for industrial and embedded systems. This far, however, the lack of real-time services has prevented this change of used network technology. This paper presents enhancements to full-duplex switched Ethernet for the ability of giving throughput and delay guarantees. The switch and the end-nodes controls the real-time traffic with Earliest Deadline First (EDF) scheduling on the frame level. No modification to the Ethernet standard is needed in the network that supports both real-time and non-real-time TCP/IP communication. The switch is responsible for admission control where feasibility analysis is made for each link between source and destination. The switch broadcasts Ethernet frames regularly to clock synchronize the end nodes and to implement flow control for non-real-time traffic.

  • 65.
    Hoang, Hoai
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Jonsson, Magnus
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Kallerdahl, Anders
    Hagström, Ulrik
    Switched real-time Ethernet with earliest deadline first scheduling - protocols and traffic handling2002In: Parallel and Distributed Computing Practices, ISSN 1097-2803, Vol. 5, no 1, p. 105-115Article in journal (Refereed)
    Abstract [en]

    There is a strong interest of using the cheap and simple Ethernet technology for industrial and embedded systems. This far, however, the lack of real-time services has prevented this change of used network technology. This paper presents enhancements to full-duplex switched Ethernet for the ability of giving throughput and delay guarantees. The switch and the end-nodes control the real-time traffic with Earliest Deadline First (EDF) scheduling on the frame level. No modification to the Ethernet standard is needed in the network that supports both real-time and non-real-time TCP/IP communication. The switch is responsible for admission control where feasibility analysis is made for each link between source and destination. The switch broadcasts Ethernet frames regularly to clock synchronize the end nodes and to implement flow control for non-real-time traffic. We have characterized the performance of the network in terms of channel acceptance ratio by simulations with different number of nodes connected to the switch.

  • 66.
    Hoang, Hoai
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Jonsson, Magnus
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Larsson, Anders
    Olsson, Richard
    Bergenhem, Carl
    Deadline first scheduling in switched real-time Ethernet - deadline partitioning issues and software implementation experiments2002In: Euromicro RTS 2002: 14th Euromicro Conference on Real-Time Systems : proceedings : 19-21 June, 2002, Vienna, Austria, Los Alamitos, Calif.: IEEE Computer Society , 2002, p. 68-71Conference paper (Refereed)
    Abstract [en]

    This paper presents work on a switched Ethernet network extended to allow for earliest deadline first (EDF) scheduling. We show by example that asymmetric deadline partitioning between the links of a real-time channel can increase the utilization substantially, still not violating the real-time guarantees. We also report measurements on a software implementation of the switch on an ordinary PC.

  • 67.
    Hoang, Hoai
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE).
    Karlsson, Stefan
    Jonsson, Magnus
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE).
    Minimum EDF-feasible deadline calculation with low-time complexity2004In: RTSS 2004 WIP Proceedings, The 25th IEEE International Real-Time Systems Symposium, Lisbon, Portugal, Dec. 5-8, 2004, 2004Conference paper (Refereed)
    Abstract [en]

    We present a method for calculating the minimum EDF-feasible deadline. The algorithm targets periodic tasks with hard real-time guarantees, that are to be feasibly scheduled with EDF (Earliest Deadline First). The output is the smallest possible deadline required for feasibility, of the task most recently requested. The good thing with our algorithm is that it has the same timecomplexity as the regular EDF feasibility test, when deadlines are not assumed to be equal to the periods of the periodic tasks.

  • 68.
    Hoang, Le-Nam
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Uhlemann, Elisabeth
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES). Mälardalen University, Västerås, Sweden.
    Jonsson, Magnus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    A Framework for Reliable Exchange of Periodic and Event-Driven Messages in Platoons2015In: 2015 IEEE International Conference on Communication Workshop, Piscataway: IEEE conference proceedings, 2015, p. 2471-2476Conference paper (Refereed)
    Abstract [en]

    Platooning is widely considered a promising approach to decrease fuel consumption by reducing the air drag. However, in order to achieve the benefits of aerodynamic efficiency, the inter-vehicle distances must be kept short. This implies that the intra-platoon communication must not only be reliable but also able to meet strict timing deadlines. In this paper, we propose a framework that reliably handles the co-existence of both time-triggered and event-driven control messages in platooning applications and we derive an efficient message dissemination technique. We propose a semi-centralized time division multiple access (TDMA) approach, which e.g., can be placed on top of the current standard IEEE 802.11p and we evaluate the resulting error probability and delay, when using it to broadcast periodic beacons and disseminating eventdriven messages within a platoon. Simulation results indicate that the proposed dissemination policy significantly enhances the reliability for a given number of available time-slots, or alternatively, reduces the delay, in terms of time-slots, required to achieve a certain target error probability, without degrading the performance of co-existing time-triggered messages. © 2015 IEEE

  • 69.
    Hoang, Le-Nam
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Uhlemann, Elisabeth
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES). Mälardalen University, Västerås, Sweden.
    Jonsson, Magnus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    A novel relaying scheme to guarantee timeliness and reliability in wireless networks2017In: 2016 IEEE Globecom Workshops (GC Wkshps): Proceedings, New York: IEEE, 2017, article id 7848822Conference paper (Refereed)
    Abstract [en]

    Many emerging applications based on wireless networks involve distributed control. This implies high requirements on reliability, but also on a predictable maximum delay and sometimes jitter. Further, many distributed control systems need to be constructed using off-the-shelf components, both due to cost constraints and due to interoperability with existing networks. This, in turn, implies that concurrent transmissions and multiuser detection are seldom possible. Instead, half-duplex time division multiple access (TDMA) is typically used. The total communication delay thereby depends on the packet error rate and the time until channel access is granted. With TDMA, channel access is upper-bounded and the jitter can be set to zero. With the aim to reduce the packet error rate given a certain deadline (a set of TDMA time-slots), we propose a novel relaying scheme, which can be implemented on top of off-the-shelf components. The paper includes a full analysis of the resulting error probability and latency. Numerical results show that the proposed relaying strategy significantly improves reliability given a certain maximum latency, or alternatively, reduces the latency, given a certain target reliability requirement. © 2016 IEEE.

  • 70.
    Hoang, Le-Nam
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Uhlemann, Elisabeth
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES). Mälardalen University, Västerås, Sweden.
    Jonsson, Magnus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    A Simple Relaying Scheme to Guarantee Timeliness and Reliability in Wireless Networks2015Manuscript (preprint) (Other academic)
    Abstract [en]

    Many emerging applications based on wireless networks involves distributed control. This implies high requirements on reliability, but also on maximum delay and sometimes jitter. The total delay depends on the packet error rate and the time until channel access is granted. With e.g., TDMA, channel access is upper-bounded and the jitter zero. To reduce the packet error rate given a certain deadline (a set of TDMA time-slots), we propose a simple relaying scheme, including a full analysis of its resulting error probability and delay. Numerical results show that the proposed relaying strategy significantly improves reliability given a certain message deadline.

  • 71.
    Hoang, Le-Nam
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Uhlemann, Elisabeth
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES). Mälardalen University, Västerås, Sweden.
    Jonsson, Magnus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    An Efficient Message Dissemination Technique in Platooning Applications2015In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 19, no 6, p. 1017-1020Article in journal (Refereed)
    Abstract [en]

    Autonomous driving in road trains, a.k.a. platooning, may reduce fuel consumption considerably if the intervehicle distances are kept short. However, to do this, the intraplatoon communication must not only be reliable but also able to meet strict deadlines. While time-triggered messages are the foundation of most distributed control applications, platooning is likely to also require dissemination of event-driven messages. While much research work has focused on minimizing the age of periodic messages, state-of-the-art for disseminating eventdriven messages is to let all nodes repeat all messages and focus on mitigating broadcast storms. We derive an efficient message dissemination scheme based on relay selection which minimizes the probability of error at the intended receiver(s) for both unicast and broadcast, without degrading the performance of co-existing time-triggered messages. We present a full analysis of the resulting error probability and delay, when relayers, selected by our algorithm, are used to disseminate messages within a platoon. Numerical results indicate that the proposed relaying policy significantly enhances the reliability for a given delay.

  • 72.
    Hoang, Le-Nam
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Uhlemann, Elisabeth
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES). Mälardalen University, Västerås, Sweden.
    Jonsson, Magnus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Cluster Relaying to Guarantee Timeliness and Reliability in Wireless NetworksManuscript (preprint) (Other academic)
    Abstract [en]

    Many emerging applications using wireless networks imply high requirements on reliability, but also on a predictable maximum delay. Due to cost constraints and interoperability with existing networks, half-duplex time division multiple access (TDMA) is typically used in these applications. With TDMA, channel access is upper-bounded and the jitter can be set to zero. However, the major drawback of TDMA is that the already-allocated time-slots are wasted if their respective transmitters do not have any packet to send. Therefore, in this paper we propose a novel cluster-relaying scheme to overcome this drawback but still reduce the probability of error given a certain deadline. Numerical results show that the proposed scheme significantly enhances reliability while guaranteeing deadline for each message.

  • 73.
    Hoang, Le-Nam
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Uhlemann, Elisabeth
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES). Mälardalen University, Västerås, Sweden.
    Jonsson, Magnus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Low Complexity Algorithm for Efficient Relay Assignment in Unicast/Broadcast Wireless Networks2017In: 2017 IEEE 85th Vehicular Technology Conference (VTC Spring), [S.l.]: IEEE, 2017Conference paper (Refereed)
    Abstract [en]

    Using relayers in wireless networks enables higher throughput, increased reliability or reduced delay. However, when building networks using commercially available hardware, concurrent transmissions by multiple relayers are generally not possible. Instead one specific relayer needs to be assigned for each transmission instant. If the decision regarding which relayer to assign, i.e., which relayer that has the best opportunity to successfully deliver the packet, can be taken online, just before the transmission is to take place, much can be gained. This is particularly the case in mobile networks, as a frequently changing network topology considerably affects the choice of a suitable relayer. To this end, this paper addresses the problem of online relay assignment by developing a low-complexity algorithm highly likely to find the optimal combination of relaying nodes that minimizes the resulting error probability at the targeted receiver(s) using a mix of simulated annealing and ant colony algorithms, such that relay assignments can be made online also in large networks. The algorithm differs from existing works in that it considers both unicast as well as broadcast and assumes that all nodes can overhear each other, as opposed to separating source nodes, relay nodes and destination nodes into three disjoint sets, which is generally not the case in most wireless networks.

  • 74.
    Hoang, Le-Nam
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Uhlemann, Elisabeth
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES). Mälardalen University, Västerås, Sweden.
    Jonsson, Magnus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Relaying with Packet Aggregation for Half-Duplex All-to-All Broadcast in Time-Critical Wireless Networks2017In: 2017 IEEE Globecom Workshops (GC Wkshps), Piscataway, NJ: IEEE, 2017Conference paper (Other academic)
    Abstract [en]

    Wireless automation and control networks, with stringent latency and reliability requirements, typically use half-duplex communications combined with deadline-aware scheduling of time slots to nodes. To introduce higher reliability in legacy industrial control systems, extra time slots are usually reserved for retransmissions. However, in distributed wireless control systems, where sensor data from several different nodes must be timely and reliably available at all places where controller decisions are made, this is particularly cumbersome as all nodes may not hear each other and extra time slots imply increased delay. To enable all-to-all broadcast with manageable overhead and complexity in such systems, we therefore propose a novel relaying strategy using packet aggregation. The strategy assigns relayers to time slots, as well as determines which packets to aggregate in each slot, using a low-complexity algorithm such that ultra-reliable communications can be obtained with maintained end-to-end latency.

  • 75.
    Huang, Chung-Ming
    et al.
    Department of Computer Science and Information Engineering, National Cheng Kung University, Tainan, Taiwan.
    Yang Lin, Shih
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Jonsson, Magnus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Proactive safety – cooperative collision warning for vehicles2015In: Clean Mobility and Intelligent Transport Systems / [ed] Michele Fiorini & Jia-Chin Lin, London: IET Digital Library, 2015, p. 117-134Chapter in book (Refereed)
    Abstract [en]

    Telematics is an interdisciplinary technology that combines telecommunications, vehicular technologies, road transportation, road safety, electrical engineering, and computer science to provide applications and services for the purpose of comfort and safety enhancement. From the timing point of view, the driving safety can be classified into two domains: (1) active safety and (2) passive safety. Passive safety systems are used to reduce damage and protect passengers and drivers when an accident occurs. Common passive safety systems include airbags, seatbelts, whiplash injury lessening systems, and energy absorbing steering column. Active safety systems are used to prevent accidents before they occur. An example of active safety system is the collision warning/avoidance system. It basically collects/detects neighboring vehicles' motion states to compute potential collision between vehicles. Based on future technology, cooperative active safety systems emerge. Vehicles can exchange their information between each other through wireless communication [1], for example, over a vehicular ad hoc network (VANET), for cooperative purposes such as collision warning/avoidance. In a project named smart intersection, a collision avoidance system based on the concept of active safety was developed by Ford and the US government [2]. The system collects a vehicle's information like Global Positioning System (GPS) coordinates, velocity, and heading and delivers it through wireless communication to other vehicles in order to prevent accidents and congestion before vehicles arrive to an intersection. To understand the details of cooperative collision warning (CCW), this chapter exposes main factors that affect the accuracy of CCW, challenges of CCW, communication techniques for cooperative safety, and collision prediction techniques. CCW systems are also introduced in detail. Moreover, we present some existing safety-related techniques and systems that are developed by automobile manufacturers. © The Institution of Engineering and Technology 2015

  • 76.
    Jonsson, Magnus
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Comments on interconnection networks for parallel radar signal processing systems1999Report (Other (popular science, discussion, etc.))
    Abstract [en]

    In this report, some high-performance interconnection networks are briefly commented/evaluated against a specific radar signal processing system selected as a general representative system

  • 77.
    Jonsson, Magnus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Control-channel based fiber-ribbon pipeline ring network1998In: Fifth International Conference on Massively Parallel Processing: proceedings : June 15-18, 1998, Las Vegas, Nevada, Piscataway, NJ.: IEEE , 1998, p. 158-165Conference paper (Refereed)
    Abstract [en]

    In this paper, we propose a control-channel based ring network built up of fiber-ribbon point-to-point links. One of the fibers in each link forms part of the control-channel ring, over which medium access control information is sent immediately before data transmissions. This increases performance of the network. High throughputs can be achieved in the network due to pipelining, i.e., several packets can be traveling through the network simultaneously but in different segments of the ring. The network can meet high performance demands in, e.g., massively parallel signal processing systems, which is shown by example in the paper. Also, real-time demands can be met using slot reserving. The network, called CC-FPR (Control-Channel based Fiber-ribbon Pipeline Ring), can be built today using fiber-optic off-the-shelf components, and a prototype is currently under development. The increasingly good price/performance ratio for fiber-ribbon links indicates a great success potential for the proposed kind of network.

  • 78.
    Jonsson, Magnus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Fiber-optic interconnection networks for signal processing applications1999In: Parallel and distributed processing : 11th [sic] IPPS/SPDP '99 workshops held in conjunction with the 13th International Parallel Processing Symposium and 10th Symposium on Parallel and Distributed Processing, San Juan, Puerto Rico, USA, April 12-16, 1999 : proceedings / [ed] José Rolim, Frank Mueller, Albert Y. Zomaya, Fikret Ercal, Stephan Olariu, Binoy Ravindran, Jan Gustafsson, Hiroaki Takada, Ron Olsson and Laxmikant V. Kale, et al., London: Springer-Verlag , 1999, Vol. 1586, p. 1374-1385Conference paper (Refereed)
    Abstract [en]

    In future parallel radar signal processing systems, with high bandwidth demands, new interconnection technologies are needed. The same reasoning can be made for other signal processing applications, e.g., those involving multimedia. Fiber-optic networks are a promising alternative and a lot of work have been done. In this paper, a number of fiber-optic interconnection architectures are reviewed, especially from a radar signal processing point-of-view. Two kinds of parallel algorithm mapping are discussed: (i) a chain of pipeline-stages mapped, more or less directly, one stage per computation node and (ii) SPMD (Same Program Multiple Data). Several network configurations, which are simplified due to the nature of the applications, are also proposed. © Springer-Verlag Berlin Heidelberg 1999

  • 79.
    Jonsson, Magnus
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Fiber-Optic Interconnections in High-Performance Real-Time Computer Systems1997Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Future parallel computer systems for embedded real-time applications,where each node in itself can be a parallel computer, are predicted to havevery high bandwidth demands on the interconnection network. Otherimportant properties are time-deterministic latency and guarantees to meetdeadlines. In this thesis, a fiber-optic passive optical star network with amedium access protocol for packet switched communication in distributedreal-time systems is proposed. By using WDM (Wavelength DivisionMultiplexing), multiple channels, each with a capacity of several Gb/s, areobtained.

    A number of protocols for WDM star networks have recently been proposed.However, the area of real-time protocols for these networks is quiteunexplored. The protocol proposed in this thesis is based on TDMA (TimeDivision Multiple Access) and uses a new distributed slot-allocationalgorithm with real-time properties. Services for both guarantee-seekingmessages and best-effort messages are supported for single destination,multicast, and broadcast transmission. Slot reserving can be used toincrease the time-deterministic bandwidth, while still having an efficientbandwidth utilization due to a simple slot release method.

    By connecting several clusters of the proposed WDM star network by abackbone star, thus forming a star-of-stars network, we get a modular andscalable high-bandwidth network. The deterministic properties of thenetwork are theoretically analyzed for both intra-cluster and inter-clustercommunication, and computer simulations of intra-cluster communicationare reported. Also, an overview of high-performance fiber-opticcommunication systems is presented.

  • 80.
    Jonsson, Magnus
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    High performance fiber-optic interconnection networks for real-time computing systems1999Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Parallel and distributed computing systems become more and more powerful and hence place increasingly higher demands on the networks that interconnect their processors or processing nodes. Many of the applications running on such systems, especially embedded systems applications, have real-time requirements and, with increasing application demands, high-performance networks are the hearts of these systems. Fiber-optic networks are good candidates for use in such systems in the future.

    This thesis contributes to the relatively unexplored area of fiber-optic networks for parallel and distributed real-time computer systems and  suggests and evaluates several fiber-optic networks and protocols. Two different technologies are used in the networks, WDM (Wavelength Division Multiplexing) and fiber-ribbon point-to-point links. WDM offers multiple channels, each with a capacity of several Gbit/s. A WDM star network in which protocols and services are efficiently integrated to support different kinds of real-time demands, especially hard ones, has been developed. The star-of-stars topology can be chosen to offer better network scalability.

    The WDM star architecture is attractive but its future success depends on components becoming more commercially mature. Fiber-ribbon links, offering instead an aggregated bandwidth of several Gbit/s, have already reached the market with a promising price/performance ratio. This has motivated the development and investigation of two new ring networks based on fiber-ribbon links. The networks take advantage of spatial bandwidth reuse, which can greatly enhance performance in applications with a significant amount of nearest downstream neighbor communication. One of the ring networks is control channel based and not only has support for real-time services like the WDM star network but also low level support for, e.g., group communication.

    The approach has been to develop network protocols with support for dynamic real-time services, out of time-deterministic static TDMA systems. The focus has been on functionality more than pure performance figures, mostly on real-time features but also on other types of functionality for parallel and distributed systems. Worst-case analyses, some simulations, and case studies are reported for the networks. The focus has been on embedded supercomputer applications, where each node itself can be a parallel computer, and it is shown that the networks are well suited for use in the radar signal processing systems studied. Other application examples in which these kinds of networks are valuable are distributed multimedia systems, satellite imaging and other image processing applications.

  • 81.
    Jonsson, Magnus
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    High-performance fiber-optic communication networks for distributed computing systems1997Report (Other academic)
    Abstract [en]

    Interconnection networks have a key role in distributed processing systems of today but to follow the evolution in processing power, new technologies are needed. Multiple-channel fiber-optic communication can solve the emerging demand of bandwidth. New protocols must, however, be used to coordinate the use of multiple high-speed channels. This paper describes protocols and fiber-optic network architectures that are considered to be useful as flexible interconnection networks in future parallel and distributed computing systems. Also, a short overview of system components and system technologies is presented.

  • 82.
    Jonsson, Magnus
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Optical interconnection technology in switches, routers and optical cross connects2003In: Optical Networks Magazine, ISSN 1388-6916, E-ISSN 1388-6916, Vol. 4, no 4, p. 20-34Article in journal (Refereed)
    Abstract [en]

    The performance of data- and telecommunication equipment must keep abreast of the increasing network speed. At the same time, it is necessary to deal with the internal interconnection complexity, which typically grows by N2 or NlogN, where N is the number of ports. This requires new interconnection technologies to be used internally in the equipment. Optical interconnection technology is a promising alternative and much work has already been done. This paper reviews a number of optical and optoelectronic interconnection architectures, especially from a data and telecommunication equipment point of view. Three kinds of systems for adopting optical interconnection technology are discussed: (i) optical cross connects (OXCs), (ii) switches and routers with some kind of burst switching and (iii) switches and routers that redirect traffic on the packet or cell level. The interconnection technologies and architectures are discussed according to their suitability for adoption in the three system types.

  • 83.
    Jonsson, Magnus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Optical Interconnection Technology in Switches, Routers and Optical Cross Connects2001In: International Conference on Parallel Processing Workshops, 2001, IEEE Computer Society , 2001, p. 319-326, article id 951968Conference paper (Refereed)
    Abstract [en]

    The performance of data- and telecommunication equipment must keep up with the increasing network speed. At the same time, one must deal with the internal interconnection complexity, often growing exponentially with the number of ports. Therefore, new interconnection technologies to be used internally in the equipment are needed. Optical interconnection technology is a promising alternative and much work has been done. In this paper, a number of optical and optoelectronic interconnection architectures are reviewed, especially from a data- and telecommunication equipment point-of-view. Three kinds of systems for adoption of optical interconnection technology are discussed: (i) optical cross connects (OXCs), (ii) switches and routers with some kind of burst switching, and (iii) switches and routers which redirect traffic on the packet or cell level. The reviewed interconnection technologies and architectures are discussed according to their suitability of adoption in the three mentioned system types.

  • 84.
    Jonsson, Magnus
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Optical interconnections in parallel radar signal processing systems1999Report (Other academic)
    Abstract [en]

    Optical interconnection networks is a promising design alternative for future parallel computer systems. Numerous configurations with different degrees of optics, optoelectronics, and electronics have been proposed. In this paper, some of these interconnection networks and technologies are briefly surveyed. Also, a discussion of their suitability in radar signal processing systems is provided, where several different ways of coarse algorithm mapping are considered.

  • 85.
    Jonsson, Magnus
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Real-Time Communication2006In: ARTES - A network for Real-Time research and graduate Education in Sweden 1997-2006, Uppsala: Uppsala universitet , 2006, p. 333-351Chapter in book (Other (popular science, discussion, etc.))
    Abstract [en]

    More and more real-time systems are complex and distributed systems consisting of many sub-systems that must cooperate. In other words, those sub-systems must communicate with each other and to do this, still fullling the overall system specfication, real-time communication must be supported. Moreover, real-time communication is also becoming widely needed in networks like the Internet, spanning over large distances. In for example Internet, the support for different traffic classes is often described as supporting different QoS (Quality of Service) levels and does normally include some kind of specifcation to meet real-time demands. Real-time communication often relies on some kind of scheduling like EDF (Earliest Deadline First), but there are some important differences compared to standard single-processor scheduling. First, the transmission of a packet is, in most cases, non-preemptive. The ongoing transmission, and possibly also some of the already queued messages, can then not be interrupted when a more important message (e.g., with a shorter relative deadline) arrives or is generated. Moreover, a network, instead of a single link, makes the situation much more complex and one must consider things like medium access method, topology, multiple users on multiple nodes, non-deterministic access delay etc.

  • 86.
    Jonsson, Magnus
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Two fiber-ribbon ring networks for parallel and distributed computing systems1998In: Optical Engineering: The Journal of SPIE, ISSN 0091-3286, E-ISSN 1560-2303, Vol. 37, no 12, p. 3196-3204Article in journal (Refereed)
    Abstract [en]

    Ring networks made of fiber-ribbon point-to-point links are proposed. The first network is a control-channel based network in which one fiber in each link joins with others to form a control-channel ring. This ring improves performance of the network by sending medium access control information immediately before the data transmissions. High throughputs can be achieved in the network due to pipelining, i.e., several packets can travel through the network simultaneously but in different segments of the ring. The network can meet tough performance demands in, e.g., massively parallel signal processing systems, which is shown by example. Also, real-time demands can be met using slot reserving. The network, called CC-FPR (control-channel based fiber-ribbon pipeline ring), can be built today using off-the-shelf fiber optic components. The increasingly good price/performance ratio for fiber-ribbon links indicates a high potential for the success of the proposed kind of networks; a prototype is currently under development. The second network is similar to first except that it divides the network into two subnetworks, one for packet-switched traffic and one for circuit-switched traffic. When the main data flow in the network does not change rapidly, this is a good choice for a simple but powerful network.

  • 87.
    Jonsson, Magnus
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Why real-time communication matters2011Conference paper (Refereed)
    Abstract [en]

    Embedded systems normally need to react to external events in time if the application requirements are to be met. Moreover, as embedded systems more and more often consist of distributed sub-systems and nodes, they must rely on communication networks. Real-time communication methods and protocols are essential for such systems and must be chosen and developed carefully. Not only real-time demands must be supported, but also high throughput, low energy consumption, high reliability and cost-efficiency, depending on the specific application. Another challenge to consider comes from the dynamics in systems properties and application requirements in some applications. Novel cooperative embedded systems might even rely on wireless connectivity where mobility and the erroneous nature of the communication medium bring new challenges. In this paper, we give examples of challenges, applications and solutions to give an understanding of the importance and possibilities of real-time communication. The aim is also to give a brief overview of research on real-time communication performed at Halmstad University, and in what contexts the results can be useful. Both systems relying on wired and wireless communication are covered.

  • 88.
    Jonsson, Magnus
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Bergenhem, Carl
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE).
    A class of Fiber-Ribbon Pipeline Ring networks for parallel and distributed computing systems2001In: PDPTA'2001: Proceedings of the International Conference on Parallel and Distributed Processing Techniques and Applications / [ed] Arabnia, H R, Athens, GA: CSREA Press, 2001, p. 1869-1875Conference paper (Refereed)
    Abstract [en]

    In this paper, three ring networks made up of fiber-ribbon point-to-point links are presented. The first network is a control-channel based network in which one fiber in each link joins with others to form a control-channel ring. This ring improves performance of the network by sending medium access control information immediately before the data transmissions. High throughputs can be achieved in the network due to pipelining, i.e., several packets can be traveling through the network simultaneously but in different segments of the ring. Also, real-time demands can be met using slot reserving. The network, called CC-FPR (Control-Channel based Fiber-ribbon Pipeline Ring), can be built today using off-the-shelf fiber-optic components. The increasingly good price/performance ratio for fiber-ribbon links indicates a high potential for the success of the proposed kind of networks. The second network is similar to the first one except that it divides the network into two sub-networks, one for packet switched traffic and one for circuit -switched traffic. When the main data flow in the network does not change rapidly, this is a good choice of a simple but powerful network. In the third network, the medium access protocol of the first network is exchanged with a one with global deadline scheduling to support best-effort real-time traffic.

  • 89.
    Jonsson, Magnus
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Bergenhem, Carl
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Olsson, Jörgen
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Fiber-ribbon ring network with services for parallel processing and distributed real-time systems1999In: Proc. SNART'99 Real-Time Systems Conference, 1999, p. 46-54Conference paper (Refereed)
    Abstract [en]

    In this paper, we present how real-time services are implemented in a control-channel based ring network built up of fiber-ribbon point-to-point links. Services for best effort messages, guarantee seeking messages and real-time virtual channels are supported for single destination, multicast and broadcast transmission by the network. Slot-reservation is used for the implementation of real-time virtual channels. High aggregated throughput can be achieved due to pipelining, i.e., data can be transmitted simultaneously in different segments of the ring. An analysis of worst-case latency and deterministic throughput, which are important measures for real-time service implementation, is provided. The network is analyzed for two variants of time-slot organization, one that offers higher throughput and one that offers lower latency in some situations. We also show how the network offers low-level support for parallel computing, i.e.,  barrier-synchronization and global reduction. The control channel is used when realizing these functions, which implies no modification of the original network architecture. Low-level support for reliable transmission is also offered in a similar manner. This includes acknowledge / negative acknowledge and flow-control.

  • 90.
    Jonsson, Magnus
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Bergenhem, Carl
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Olsson, Jörgen
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Fiber-ribbon ring network with services for parallel processing and distributed real-time systems1999In: Proc. ISCA 12th International Conference on Parallel and Distributed Computing Systems (PDCS-99), ISCA , 1999, p. 94-101Conference paper (Refereed)
    Abstract [en]

    In this paper, we present how real-time services are implemented in a control-channel based ring network built up of fiber-ribbon point-to-point links. Services for best effort messages, guarantee seeking messages and real-time virtual channels are supported for single destination, multicast and broadcast transmission by the network. Slot-reservation is used for the implementation of real-time virtual channels. High aggregated throughput can be achieved due to pipelining, i.e., data can be transmitted simultaneously in different segments of the ring. An analysis of worst-case latency and deterministic throughput, which are important measures for real-time service implementation, is provided. The network is analyzed for two variants of time-slot organization, one that offers higher throughput and one that offers lower latency in some situations. We also show how the network offers low-level support for parallel computing, i.e.,  barrier-synchronization and global reduction. The control channel is used when realizing these functions, which implies no modification of the original network architecture. Low-level support for reliable transmission is also offered in a similar manner. This includes acknowledge / negative acknowledge and flow-control.

  • 91.
    Jonsson, Magnus
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Börjesson, Klas
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Legardt, Magnus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Dynamic time-deterministic traffic in a fiber-optic WDM star network1997In: Proceedings: Ninth Euromicro Workshop on Real Time Systems, June 11-13, 1997, Toledo, Spain, Piscataway, NJ.: IEEE Computer Society, 1997, p. 25-33, article id 613760Conference paper (Refereed)
    Abstract [en]

    A number of protocols for WDM (Wavelength Division Multiplexing) star networks have been proposed. However, the area of real-time protocols for these networks is quite unexplored. In this paper, a real-time protocol, based on TDM (Time Division Multiplexing), for fiber-optic star networks is presented. By the use of WDM, multiple Gb/s channels are achieved. Services for both guarantee-seeking messages and best-effort messages are supported for single destination, multicast, and broadcast transmission. Slot reserving can be used to increase the time-deterministic bandwidth, while still having an efficient bandwidth utilization due to a simple slot release method. The deterministic properties of the protocol are analyzed and simulation results presented. © 1997 IEEE

  • 92.
    Jonsson, Magnus
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Kunert, Kristina
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    MC-EDF: A control-channel based wireless multichannel MAC protocol with real-time support2012In: Proceedings of 2012 IEEE 17th International Conference on Emerging Technologies and Factory Automation, ETFA 2012: September 17-21, 2012, Krakow, Poland, Piscataway, US: Institute of Electrical and Electronics Engineers , 2012, article id 6489558Conference paper (Refereed)
  • 93.
    Jonsson, Magnus
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Kunert, Kristina
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Meeting reliability and real-time demands in wireless industrial communication2008In: IEEE Symposium on Emerging Technologies and Factory Automation, ETFA, Piscataway, N.J.: IEEE Press, 2008, p. 877-884Conference paper (Refereed)
    Abstract [en]

    Employing wireless communication in industrial applications requires methods that deal with the high fraction of packet errors common to wireless transmissions. At the same time, industrial applications have real-time demands that protocols like TCP are unable to support. This paper combines ARQ (automatic repeat request) with real-time worst-case scheduling analysis to achieve both high reliability and real-time support. One or several retransmission attempts of erroneous data packets are handled, while still not jeopardizing stated delay guarantees of other packets. We present the real-time analysis for a full-duplex link using our retransmission scheme. In simulation studies, we demonstrate a possible reduction of the message error rate by several orders of magnitude for bit error rates typically experienced in wireless communication.

  • 94.
    Jonsson, Magnus
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Kunert, Kristina
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Reliable hard real-time communication in industrial and embedded systems2008In: SIES'2008 - 3rd International Symposium on Industrial Embedded Systems, IEEE Xplore Digital Library , 2008, p. 184-191Conference paper (Refereed)
    Abstract [en]

    This paper presents a framework for how to use ARQ (automatic repeat request) in combination with real-time worst-case scheduling analysis to be able to support reliable hard real-time communication. We show how to handle retransmissions of erroneous data packets, while still not jeopardizing stated delay guarantees of other packets. We demonstrate this by taking a point-to-point link as an example. Through our simulation studies we have shown that a reduction of the message error rate by several orders of magnitude is possible with a reasonable utilization penalty.

  • 95.
    Jonsson, Magnus
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Kunert, Kristina
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Towards reliable wireless industrial communication with real-time guarantees2009In: IEEE Transactions on Industrial Informatics, ISSN 1551-3203, E-ISSN 1941-0050, Vol. 5, no 4, p. 429-442Article in journal (Refereed)
    Abstract [en]

    Increased mobility coupled with a possible reduction of cabling costs and deployment time makes wireless communication an attractive alternative for the automation industry and related application areas. Methods compensating for the high probability of bit errors accompanying wireless transmissions are, however, needed. This is predominantly important in industrial applications with strict reliability and timing requirements, which cannot be met by standard communication protocols as e.g. TCP. In this paper, way of combining retransmissions with real-time worst-case scheduling analysis is presented that can offer both a high grade of reliability and hard real-time support. The presented solution handles one or several retransmission attempts of erroneous data without jeopardizing already guaranteed delay bounds of other packets. A real-time analysis for a full-duplex, asymmetric link, utilizing the novel retransmission scheme and supporting both piggybacked and nonpiggybacked acknowledgements, is provided. A simulation study is presented that evaluates the performance of the retransmission scheme for bit error rates typically experienced in wireless communication. The results clearly indicate a possible reduction of the message error rate by several orders of magnitude.

  • 96.
    Jonsson, Magnus
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Kunert, Kristina
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Wired and wireless reliable real-time communication in industrial systems2010In: Factory Automation / [ed] Javier Silvestre-Blanes, Vienna, Austria: IN-TECH , 2010, p. 161-176Chapter in book (Other academic)
    Abstract [en]

    In modern factory automation systems, data communication plays a vital role. Different nodes like control systems, sensors and actuators can communicate over a wireless or wired industrial network. The data traffic generated is often scheduled for periodic transmission, where each single message or packet must arrive in time. For this real-time communication, methods have been developed to support communication services with a guaranteed throughput and delay bound for such periodic traffic, but merely under the assumption of error-free communication. However, the possibility for errors in the transmission still exists due to, e.g. noise or interference. A node receiving sensor values from a sensor in the system might then be forced to rely upon an older sensor value from the latest period, possibly leading to inaccuracies in control loops which can compromise the functioning of the system. In safety-critical systems, redundant networks or communication channels are frequently added to cope with errors, leading to more expensive systems. In this chapter, we will describe an alternative approach where erroneous data packets are retransmitted in a way that does not jeopardise any earlier stated real-time guarantees for ordinary transmissions. Using our framework, the reliability of real-time communication can be increased in a more cost-efficient way. We describe in this chapter an overview of our framework for reliable real-time communication, while details of our approach can be found in our earlier publications. In the light of the emerging use of wireless communication, the framework proves to be especially useful due to the high bit error rate inherent to the wireless medium. However, the framework is naturally also attractive for wired communication systems.

  • 97.
    Jonsson, Magnus
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Kunert, Kristina
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Bilstrup, Urban
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    A real-time medium access protocol supporting dynamic spectrum allocation in industrial networks2013In: Multiple Access Communications: 6th International Workshop, MACOM 2013, Vilnius, Lithuania, December 16-17, 2013. Proceedings / [ed] Magnus Jonsson, Alexey Vinel, Boris Bellalta, Ninoslav Marina, Desislava Dimitrova, Dieter Fiems, Heidelberg: Springer, 2013, p. 54-69Conference paper (Refereed)
    Abstract [en]

    Cognitive radio with spectrum sensing and spectrum reuse has great opportunities for industrial networking. Adapting to the current interference situation and utilising the available frequencies in an effective manner can greatly improve the data delivery capabilities. At the same time, real-time demands must be met. In this paper, we present a medium access control protocol supporting dynamic spectrum allocation as done in cognitive radio networks, providing deterministic medium access for heterogeneous traffic. The possibility of spectrum sensing in the nodes opens up for the possibility of increasing successful data transmissions, and a real-time analysis framework with three formalized constraints to be tested provides support for guaranteed timely treatment of hard real-time traffic. The real-time analysis framework includes a new type of delay check that more exactly bounds the delay compared to earlier work. Simulation experiments and performance comparisons are provided. © 2013 Springer International Publishing

  • 98.
    Jonsson, Magnus
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Kunert, Kristina
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Böhm, Annette
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Increased communication reliability for delay-sensitive platooning applications on top of IEEE 802.11p2013In: Communication Technologies for Vehicles: 5th International Workshop, Nets4Cars/Nets4Trains 2013, Villeneuve d’Ascq, France, May 14-15, 2013. Proceedings / [ed] Marion Berbineau, Magnus Jonsson, Jean-Marie Bonnin, Soumaya Cherkaoui, Marina Aguado, Cristina Rico-Garcia, Hassan Ghannoum, Rashid Mehmood, Alexey Vinel, Heidelberg: Springer Berlin/Heidelberg, 2013, p. 121-135Conference paper (Refereed)
    Abstract [en]

    Cooperative driving in platooning applications has received much attention lately due to its potential to lower fuel consumption and improve safety and efficiency on our roads. However, the recently adopted standard for vehicular communication, IEEE 802.11p, fails to support the level of reliability and real-time properties required by highly safety-critical applications. In this paper, we propose a communication and real-time analysis framework over a dedicated frequency channel for platoon applications and show that our retransmission scheme is able to decrease the message error rate of control data exchange within a platoon of moderate size by several orders of magnitude while still guaranteeing that all delay bounds are met. Even for long platoons with up to seventeen members the message error rate is significantly reduced by retransmitting erroneous packets without jeopardizing the timely delivery of regular data traffic. © 2013 Springer-Verlag.

  • 99.
    Jonsson, Magnus
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Kunert, Kristina
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Böhm, Annette
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Increasing the probability of timely and correct message delivery in road side unit based vehicular communication2012In: IEEE Conference Intelligent Transportation Systems (ITSC), 2012 15th International Conference, Piscataway: IEEE Press, 2012, p. 672-679Conference paper (Refereed)
    Abstract [en]

    Intelligent transport systems provide a multitude of possibilities when it comes to increasing traffic safety on our roads. Many of the proactive traffic safety applications under development today demand timely and reliable treatment of deadline dependent data traffic. Unfortunately it is not possible to provide any timing guarantees when using the current IEEE 802.11p standard for wireless access in vehicular environments. Additionally, a difficult wireless channel environment makes successful data transmissions very challenging. We suggest adding a real-time layer, comprising a deterministic medium access control protocol and transport layer retransmissions, on top of IEEE 802.11p in order to enable guaranteed real-time behaviour and to improve reliability. In a simulation study we show that the packet error rate can be decreased by several orders of magnitude while being able to guarantee timely treatment of both ordinary transmissions and retransmissions by the help of a real-time schedulability analysis.

  • 100.
    Jonsson, Magnus
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Kunert, Kristina
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Kallerdahl, Anders
    Mentor Graphics Scandinavia AB, Gothenburg, Sweden.
    Analysing AFDX Networks Using End-to-end Response Time Analysis2015In: Journal of Interconnection Networks (JOIN), ISSN 0219-2659, Vol. 14, no 4, article id 1350017Article in journal (Refereed)
    Abstract [en]

    In this paper, we present a novel real-time analysis framework for AFDX (Avionics Full Duplex Switched Ethernet) networks. The framework, based on end-to-end response time analysis, calculates not only delay bounds, but also the maximum jitter for each VL (Virtual Link) at each hop, which is necessary according to the AFDX standard. Moreover, the framework supports multicasting, i.e., VLs with several paths, and VLs with arbitrary delay bounds, i.e., shorter, longer, or equal to their periods. An analysis method to calculate the worst-case buffer population is included in the framework, as it is important to guarantee that no buffer-overflow occurs. With a performance surpassing that of Network Calculus and comparable with Trajectory Approach, our framework presents a good choice due to its many features and its foundation in well-accepted analysis methods.

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