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  • 1.
    Böhm, Annette
    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).
    Kunert, Kristina
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    A fibre-optic AWG-based real-time network for high-performance embedded computing2004Conference paper (Refereed)
    Abstract [en]

    In this paper, an architecture and a Medium Access Control (MAC) protocol for a multiwavelength optical communication network, applicable in short range communication systems like System Area Networks (SANs), are proposed. The main focus lies on guaranteed support for hard and soft real-time traffic. The network is based upon a single-hop star topology with an Arrayed Waveguide Grating (AWG) at its center. Traffic scheduling is centralized in one node (residing together with the AWG in a hub), which communicates through a physical control channel. The AWG’s property of spatial wavelength reuse and the combination of fixedtuned and tunable transceivers in the nodes enable simultaneous control and data transmission. A case study with defined real-time communication requirements in the field of Radar Signal Processing (RSP) was carried out and indicates that the proposed system is very suitable for this kind of application.

  • 2.
    Böhm, Annette
    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).
    Kunert, Kristina
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    AWG-based Optoelectronic Router with QoS Support2005In: 2005 International Conference on Wireless and Optical Communications Networks: March 6 - 8, 2005, Dubai, United Arab Emirates, Piscataway, NJ: IEEE Press, 2005, p. 23-28Conference paper (Refereed)
    Abstract [en]

    We present a router architecture with electronic queuing and a passive optical multi-channel network, which is based upon a single-hop star topology with an arrayed waveguide grating (AWG) at its center. The AWG's property of spatial wavelength reuse and both fixed-tuned and tunable transceivers enable simultaneous control and data transmission. Our proposed medium access control protocol supports traffic differentiation and utilizes EOF (earliest deadline first) to schedule the traffic from input ports to output ports on the router. Our simulations show that the router treats QoS (quality of service) traffic well.

  • 3.
    Böhm, Annette
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS).
    Jonsson, Magnus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Kunert, Kristina
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS).
    Hoang, Hoai
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS).
    A Fibre-Optic AWG-Based Real-Time Network and Its Applicability to High-Performance Embedded Computing2005In: 19th International Parallel and Distributed Processing Symposium: proceedings, Piscataway, N.J.: IEEE Press, 2005, p. 133b-133b, article id 1419972Conference paper (Refereed)
    Abstract [en]

    In this paper, an architecture and a Medium Access Control (MAC) protocol for a multi-wavelength optical communication network, applicable in short range communication systems like System Area Networks (SANs), are proposed. The main focus lies on guaranteed support for hard and soft real-time traffic. The network is based upon a single-hop star topology with an Arrayed Waveguide Grating (AWG) at its center. Traffic scheduling is centralized in one node (residing together with the AWG in a hub), which communicates through a physical control channel. The AWG's property of spatial wavelength reuse and the combination of fixed-tuned and tunable transceivers in the nodes enable simultaneous control and data transmission. A case study with defined real-time communication requirements in the field of Radar Signal Processing (RSP) was carried out and indicates that the proposed system is very suitable for this kind of application.

  • 4.
    Böhm, Annette
    et al.
    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).
    Kunert, Kristina
    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).
    Context-Aware Retransmission Scheme for Increased Reliability in Platooning Applications2014In: Communication Technologies for Vehicles: 6th International Workshop, Nets4Cars/Nets4Trains/Nets4Aircraft 2014, Offenburg, Germany, May 6-7, 2014. Proceedings, Cham: Springer, 2014, p. 30-42Conference paper (Refereed)
    Abstract [en]

    Recent advances in cooperative driving hold the potential to significantly improve safety, comfort and efficiency on our roads. An application of particular interest is platooning of vehicles, where reduced inter-vehicle gaps lead to considerable reductions in fuel consumption. This, however, puts high requirements on timeliness and reliability of the underlying exchange of control data. Considering the difficult radio environment and potentially long distances between communicating platoon members, as well as the random channel access method used by the IEEE 802.11p standard for short-range inter-vehicle communication, those requirements are very difficult to meet. The relatively static topology of a platoon, however, enables us to preschedule communication within the platoon over a dedicated service channel. Furthermore, we are able to set aside parts of the available bandwidth for retransmission of packets in order to fulfil the reliability requirements stated by the platoon control application. In this paper, we describe the platooning framework along with the scheduling algorithm used to assign retransmission slots to control packets that are most likely to need them. This retransmission scheduling scheme offers a valuable tool for system designers when answering questions about the number of safely supported vehicles in a platoon, achievable reductions in inter-vehicle gaps and periodicity of control packets. © 2014 Springer International Publishing.

  • 5.
    Böhm, Annette
    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).
    Data age based MAC scheme for fast and reliable communication within and between platoons of vehicles2016In: International Conference on Wireless and Mobile Computing, Networking and Communications, Piscataway: IEEE, 2016Conference paper (Refereed)
    Abstract [en]

    Heavy vehicles driving as platoon with highly reduced inter-vehicle gaps has shown considerable fuel saving potential, but put high timing and reliability requirements on the underlying control data exchange. The recently standardized IEEE 802.11p protocol suite for Vehicular Ad-Hoc Networks (VANETs) and its message types do neither support the demands of a platooning application nor take advantage of its properties. We therefore propose a framework for centralized channel access with retransmission capabilities for safety critical control data exchange based on the data age of earlier received messages, DA-RE (Data Age based REtransmission scheme). A simulation comparison to the 802.11p random access Medium Access Control (MAC) protocol shows that the intelligent assignment of retransmission opportunities considerably improves the reliability of platooning control data. We also propose a power control based scheme for early platoon detection allowing several platoons to temporarily share a channel and show that the safe and reliable operation of their vehicles is not compromised. © 2016 IEEE.

  • 6.
    Böhm, Annette
    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).
    Data age based retransmission scheme for reliable control data exchange in platooning applications2015In: 2015 IEEE International Conference on Communication Workshop (ICCW), Piscataway, NJ: IEEE Press, 2015, p. 2412-2418Conference paper (Refereed)
    Abstract [en]

    Recent advances in cooperative driving hold the potential to significantly improve safety, comfort and efficiency on our roads. Platooning of heavy vehicles, where automated or semi-automated driving allows minimal inter-vehicle gaps, has shown considerable reductions in fuel consumption. Although using the same wireless communication technology, a platoon differs from a VANET (Vehicular Ad-hoc NETwork) in several points. It is centralized in its nature, with a well-defined group leader, its topology is fairly stable and it has very challenging requirements on timeliness and reliability of its control data exchange. Therefore, the IEEE 802.11p protocol suite and its recently defined message types do neither support the needs of a platooning application nor take advantage of its properties. A platoons control loop must continuously be fed with fresh data, so the information age is an important parameter to be closely monitored. In this paper, we therefore propose a framework for centralized channel access and retransmission capabilities for safety critical inter-platoon control data based on the data age of earlier received messages. A simulation evaluation compares our solution to a) the decentralized, standard-compliant IEEE 802.11p MAC (Medium Access Control) method, and a time-slotted scheme b) with and c) without retransmissions and shows that the centralized, data age based retransmission scheme clearly outperforms its competitors in terms of maintained data age. © 2015 IEEE.

  • 7.
    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

  • 8.
    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)
  • 9.
    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.

  • 10.
    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.

  • 11.
    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.

  • 12.
    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.

  • 13.
    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

  • 14.
    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.

  • 15.
    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.

  • 16.
    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.

  • 17.
    Kunert, Kristina
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Architectures and Protocols for Performance Improvements of Real-Time Networks2010Doctoral thesis, monograph (Other academic)
    Abstract [en]

    When designing architectures and protocols for data traffic requiring real-time services, one of the major design goals is to guarantee that traffic deadlines can be met. However, many real-time applications also have additional requirements such as high throughput, high reliability, or energy efficiency. High-performance embedded systems communicating heterogeneous traffic with high bandwidth and strict timing requirements are in need of more efficient communication solutions, while wireless industrial applications, communicating control data, require support of reliability and guarantees of real-time predictability at the same time. To meet the requirements of high-performance embedded systems, this thesis work proposes two multi-wavelength high-speed passive optical networks. To enable reliable wireless industrial communications, a framework in­corporating carefully scheduled retransmissions is developed. All solutions are based on a single-hop star topology, predictable Medium Access Control algorithms and Earliest Deadline First scheduling, centrally controlled by a master node. Further, real-time schedulability analysis is used as admission control policy to provide delay guarantees for hard real-time traffic.

    For high-performance embedded systems an optical star network with an Arrayed Waveguide Grating placed in the centre is suggested. The design combines spatial wavelength re­use with fixed-tuned and tuneable transceivers in the end nodes, enabling simultaneous transmis­sion of both control and data traffic. This, in turn, permits efficient support of heterogeneous traf­fic with both hard and soft real-time constraints. By analyzing traffic dependencies in this mul­tichannel network, and adapting the real-time schedulability analysis to incorporate these traffic dependencies, a considerable increase of the possible guaranteed throughput for hard real-time traffic can be obtained.

    Most industrial applications require using existing standards such as IEEE 802.11 or IEEE 802.15.4 for interoperability and cost efficiency. However, these standards do not provide predict­able channel access, and thus real-time guarantees cannot be given. A framework is therefore de­veloped, combining transport layer retransmissions with real-time analysis admission control, which has been adapted to consider retransmissions. It can be placed on top of many underlying communication technologies, exemplified in our work by the two aforementioned wireless stan­dards. To enable a higher data rate than pure IEEE 802.15.4, but still maintaining its energy saving properties, two multichannel network architectures based on IEEE 802.15.4 and encompassing the framework are designed. The proposed architectures are evaluated in terms of reliability, utiliza­tion, delay, complexity, scalability and energy efficiency and it is concluded that performance is enhanced through redundancy in the time and frequency domains.

  • 18.
    Kunert, Kristina
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Fibre-Optic AWG Networks Supporting Real-Time Communication in High-Performance Embedded Systems2008Licentiate thesis, monograph (Other academic)
    Abstract [en]

    High-performance embedded systems communicating heterogeneous traffic with high bandwidth and strict timing requirements are in need of more efficient communication solutions. This thesis proposes two multi-wavelength passive optical networks able to meet these demands. The networks are based upon a single-hop star topology with an Arrayed Waveguide Grating (AWG) placed in the centre. The intended application areas for the two networks are short range embedded communication systems like System Area Networks (SANs) and router architectures with electronic queuing. The AWG’s attractive property of spatial wavelength reuse, as well as the combination of fixed-tuned and tuneable transceivers in the end nodes, enables simultaneous control and data traffic transmission. This, in turn, makes it possible to support heterogeneous traffic with both hard and soft real-time constraints.

    Additionally, two Medium Access Control (MAC) protocols, one for each network solution, are developed. Traffic scheduling is centrally controlled by a node, the protocol processor, residing together with the AWG in a hub. All nodes use Earliest Deadline First (EDF) scheduling and communicate with the protocol processor through physical control channels. A case study, including simulations, in the field of Radar Signal Processing (RSP) and simulations using periodic real-time traffic are conducted for the two application areas respectively, showing very good results. Further, a deterministic real-time analysis is conducted to provide throughput and delay guarantees for hard real-time traffic and an increase in guaranteed traffic is achieved through an analysis of existing traffic dependencies in a multichannel network. Simulation results incorporating the traffic dependency analysis indicate a considerable increase in the possible guaranteed throughput of hard real-time traffic.

  • 19.
    Kunert, Kristina
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Improving the scheduling analysis of hard real-time traffic by analyzing traffic dependencies2008Report (Other academic)
    Abstract [en]

    Support for hard real-time traffic requires throughput guarantees for packets with timing constraints. The deterministic analysis available for real-time communication has its origin in the area of task scheduling in real-time systems and has been mapped onto the communication context. Mapping uniprocessor scheduling techniques directly on a multichannel network with the possibility of concurrent transmissions, however, introduces pessimism to the analysis. This paper presents an approach of successfully increasing the amount of possible guarantees by analyzing traffic interdependencies. By taking into account those traffic interdependencies and integrating concurrent transmissions into the analysis, the amount of throughput guarantees can be increased considerably as shown in our simulations.

  • 20.
    Kunert, Kristina
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES). 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), Embedded Systems (CERES).
    Bilstrup, Urban
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Deterministic real-time medium access for cognitive industrial radio networks2012In: 2012 9th IEEE International Workshop Factory Communication Systems: WFWC 2012, Proceedings / [ed] Thomas Nolte & Andreas Willig, Piscataway: IEEE Press, 2012, p. 91-94Conference paper (Refereed)
    Abstract [en]

    Industrial communication often has to work in an environment where other networks or radiation create different levels of interference for the data traffic. Additionally, industrial applications often demand predictable real-time performance of the network. One way of trying to utilise the available frequencies in an effective manner is to include cognitive functionality in the network. We present a medium access control protocol for a cognitive radio network, providing deterministic medium access for heterogeneous traffic and dynamic spectrum allocation. Spectrum sensing abilities in the nodes open up for the possibility of increasing successful data transmissions, and a real-time analysis framework provides upper-bounded medium access delay in order to guarantee timely treatment of hard real-time traffic. © 2012 IEEE.

  • 21.
    Kunert, Kristina
    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).
    Böhm, Annette
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    AWG-based optoelectronic router supporting both guaranteed and best-effort QoS traffic2005Conference paper (Refereed)
    Abstract [en]

    We present a router architecture with electronic queuing and a passive optical multi-channel network, based upon a single-hop star topology with an Arrayed Waveguide Grating (AWG) at its centre. The AWG’s property of spatial wavelength reuse and both fixed-tuned and tuneable transceivers enable simultaneous control and data transmission. Our proposed medium access control protocol supports traffic differentiation and utilizes EDF (Earliest Deadline First) to schedule the traffic from input ports to output ports on the router. Our simulations show that the router treats QoS (Quality of Service) traffic well.

  • 22.
    Kunert, Kristina
    et al.
    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).
    Böhm, Annette
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Nordström, Tomas
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Providing Efficient Support for Real-Time Guarantees in a Fibre-Optic AWG-Based Network for Embedded Systems2017In: Optical Switching and Networkning Journal, ISSN 1573-4277, E-ISSN 1872-9770, Vol. 24, p. 47-56Article in journal (Refereed)
    Abstract [en]

    High-performance embedded systems running real-time applications demand communication solutions providing high data rates and low error probabilities, properties inherent to optical solutions. However, providing timing guarantees for deadline bound applications in this context is far from basic due to the parallelism inherent in multiwavelength networks and often bound to include a large amount of pessimism. Assuming deterministic medium access, an admission control algorithm using a schedulability analysis can ensure deadline guarantees for real-time communication. The traffic dependency analysis presented in this paper is specifically targeting a multichannel context, taking into consideration the possibility of concurrent transmissions in these types of networks. Combining our analysis with a feasibility analysis in admission control, the amount of guaranteed hard real-time traffic could be shown to increase by a factor 7 in a network designed for a radar signal processing case. Using this combination of analysis methods will render possible an increased amount of hard real-time traffic over a given multichannel network, leading to a more efficient bandwidth utilization by deadline dependent applications without having to redesign the network or the medium access method.

  • 23.
    Kunert, Kristina
    et al.
    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).
    Uhlemann, Elisabeth
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Exploiting Time and Frequency Diversity in IEEE 802.15.4 Industrial Networks for Enhanced Reliability and Throughput2010In: 2010 IEEE CONFERENCE ON EMERGING TECHNOLOGIES AND FACTORY AUTOMATION (ETFA), Piscataway: IEEE , 2010, article id 5641347Conference paper (Refereed)
    Abstract [en]

    Industrial networks based on IEEE 802.15.4 are spreading, even though the joint requirement on predictability and reliability from industrialapplications is hard to fulfil in wireless networks, and the data rate of IEEE 802.15.4 is rather low. With the goal of providing real-time guarantees, with increased reliability and throughput, we propose two multichannel network architectures based on IEEE 802.15.4 with predictable medium access, real-time analysis admission control and transport layer retransmissions. We evaluate the architectures in terms of reliability, utilization, delay, complexity, scalability and energy efficiency. The evaluations show that throughput and reliability can be enhanced through redundancy and concurrency in the frequency domain. ©2010 IEEE.

  • 24.
    Kunert, Kristina
    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).
    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).
    Uhlemann, Elisabeth
    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).
    Exploiting time and frequency diversity in IEEE 802.15.4 industrial networks for enhanced reliability and throughput2010In: 2010 IEEE Conference on Emerging Technologies and Factory Automation (ETFA), Piscataway, NJ, 2010, p. 1-9Conference paper (Refereed)
    Abstract [en]

    Industrial networks based on IEEE 802.15.4 are spreading, even though the joint requirement on predictability and reliability from industrial applications is hard to fulfil in wireless networks, and the data rate of IEEE 802.15.4 is rather low. With the goal of providing real-time guarantees, with increased reliability and throughput, we propose two multichannel network architectures based on IEEE 802.15.4 with predictable medium access, real-time analysis admission control and transport layer retransmissions. We evaluate the architectures in terms of reliability, utilization, delay, complexity, scalability and energy efficiency. The evaluations show that throughput and reliability can be enhanced through redundancy and concurrency in the frequency domain.

  • 25.
    Kunert, Kristina
    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).
    Uhlemann, Elisabeth
    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).
    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).
    Enhancing reliability in IEEE 802.11 based real-time networks through transport layer retransmissions2010In: 2010 International Symposium on Industrial Embedded Systems (SIES), New York: IEEE Press, 2010, p. 146-155Conference paper (Refereed)
    Abstract [en]

    As the number of application areas for wireless technologies grows, the need for providing both predictable and reliable communication over wireless networks becomes apparent. Cooperative embedded systems for industrial automation are one example of systems with these needs. Previously, we developed a framework for reliable real-time communication in a single-hop wireless network with a logical star topology. The framework was placed on top of IEEE 802.15.4 and combines transport layer retransmissions with real-time analysis admission control. IEEE 802.15.4 was selected due to its advantageous energy saving techniques, making it an interesting choice for wireless sensor networks in industrial contexts. However, its achievable data rate is rather low, especially when voice or video for industrial surveillance and monitoring need to be transferred. Hence, we adapt our framework to fit the IEEE 802.11 standard and evaluate its performance using a data traffic model from industrial control and surveillance systems. The performance of the framework is evaluated in terms of network utilization, message error rate and delay distribution using theoretical analysis as well as computer simulations.

     

  • 26.
    Kunert, Kristina
    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).
    Uhlemann, Elisabeth
    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).
    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).
    Predictable real-time communications with improved reliability for IEEE 802.15.4 based industrial networks2010In: 2010 8th IEEE International Workshop on Factory Communication Systems (WFCS), Piscataway, N.J.: IEEE , 2010, p. 13-22Conference paper (Refereed)
    Abstract [en]

    Emerging industrial applications requiring reliable wireless real-time communications are numerous. Using existing standards such as IEEE 802.15.4 is essential for reasons of interoperability and cost efficiency. However, since 802.15.4 is unable to provide predictable channel access, real-time guarantees cannot be given. Further, the noisy wireless channel makes reliable communications particularly challenging. By adding a deterministic medium access method and a transport protocol with a truncated retransmission scheme to 802.15.4, we jointly enforce reliability and predictability. We evaluate our solution analytically by real-time schedulability analysis including retransmissions, and by computer simulations. We show that the message error rate can be improved by several orders of magnitude while keeping the utilization penalty at reasonable levels.

  • 27.
    Kunert, Kristina
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Weckstén, Mattias
    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).
    Algorithm for the choice of topology in reconfigurable networks with real-time support2007Report (Other academic)
    Abstract [en]

    Many future embedded systems are likely to contain System-on-Chip solutions with on-chip networks, and to achieve high aggregated throughputs in these networks, a switched topology can be used. For further performance improvements, the topology can be adapted to application demands, either when designing the chip or by run-time reconfiguration between different predefined application modes. In this report, we describe an algorithm for the choice of topology in, e.g., packet-switched on-chip networks, considering the real-time demands in terms of throughput and delay often put on such systems. To further address possible real-time demands, we include a feasibility analysis to check that the application, when mapped onto the system, will behave in line with its real-time demands. With input information about the traffic characteristics, our algorithm creates a topology and generates routing information for all logical traffic channels. In a case study, we show that our algorithm results in a topology that can outperform the use of state of the art topologies for high-performance computer architectures. Although we have targeted for reconfigurable Network-on-Chip architectures, the algorithm can also be used for other systems. Our algorithm gives the opportunity for topology choice at design stage, both for static network topologies and for reconfigurable network topologies that can be reconfigured during run-time.

  • 28.
    Kunert, Kristina
    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).
    Weckstén, Mattias
    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).
    Algorithm for the choice of topology in reconfigurable on-chip networks with real-time support2007In: Proceedings of the 2nd international conference on Nano-Networks, Bryssels: ICST (Institute for Computer Sciences, Social-Informatics and Telecommunications Engineering) , 2007, p. 1-7Conference paper (Refereed)
    Abstract [en]

    Many future embedded systems are likely to contain System-on-Chip solutions with on-chip networks and in order to achieve high aggregated throughputs in these networks, a switched topology can be used. For further performance improvements, the topology can be adapted to application demands, either when designing the chip or by run-time reconfiguration between different predefined application modes. In this paper, we present an algorithm for the choice of topology in, e.g., on-chip networks, considering realtime demands in terms of throughput and delay often put on such systems. To further address possible real-time demands, we include a feasibility analysis to check that the application, when mapped onto the system, will behave in line with its real-time demands. With input information about traffic characteristics, our algorithm creates a topology and generates routing information for all logical traffic channels. In a case study, we show that our algorithm results in a topology that can outperform the use of state of the art topologies for high-performance computer architectures.

  • 29.
    Ramazanali, Hawar
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES). Saab Training and Simulation, Huskvarna, Sweden.
    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).
    Bilstrup, Urban
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Military Training Network with Admission Control using Real-Time Analysis2014In: 2014 IEEE 19th International Workshop on Computer Aided Modeling and Design of Communication Links and Networks (CAMAD), Piscataway, NJ: IEEE Press, 2014, p. 249-254, article id 7033244Conference paper (Refereed)
    Abstract [en]

    Military training radio networks typically consist of large numbers of mobile nodes and have to provide real-time (RT) communication between these nodes. This paper introduces a method on how to manage radio resources and provide Quality of Service (QoS) guarantees for heterogeneous traffic by using admission control, deterministic queuing, and scheduling methods. The proposed solution is based on the use of a RT feasibility test in the admission control and earliest deadline first (EDF) scheduling and queuing. This deterministic solution handles heterogeneous traffic through a novel combination of RT downlink and two types of RT uplink dynamic scheduling mechanisms. The uplink scheduling consists of a control packet based mechanism for sporadic RT traffic and a periodic short-latency mechanism for periodic RT traffic. The method presented in this paper is investigated by computer simulation, evaluating its performance and determining the maximum number of nodes supported, given a worst-case user scenario. To the best of our knowledge this is the first centralized protocol designed for a military training network providing application-specific RT support for heterogeneous traffic. ©2014 IEEE.

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