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  • 1.
    Abbas, Taimoor
    et al.
    Lund Univ, Elect & Informat Technol Dept, S-22100 Lund, Sweden..
    Sjöberg, Katrin
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Kåredal, Johan
    Lund Univ, Elect & Informat Technol Dept, S-22100 Lund, Sweden..
    Tufvesson, Fredrik
    Lund Univ, Elect & Informat Technol Dept, S-22100 Lund, Sweden..
    A Measurement Based Shadow Fading Model for Vehicle-to-Vehicle Network Simulations2015Inngår i: International Journal of Antennas and Propagation, ISSN 1687-5869, E-ISSN 1687-5877, artikkel-id 190607Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The vehicle-to-vehicle (V2V) propagation channel has significant implications on the design and performance of novel communication protocols for vehicular ad hoc networks (VANETs). Extensive research efforts have been made to develop V2V channel models to be implemented in advanced VANET system simulators for performance evaluation. The impact of shadowing caused by other vehicles has, however, largely been neglected in most of the models, as well as in the system simulations. In this paper we present a shadow fading model targeting system simulations based on real measurements performed in urban and highway scenarios. The measurement data is separated into three categories, line-of-sight (LOS), obstructed line-of-sight (OLOS) by vehicles, and non-line-of-sight due to buildings, with the help of video information recorded during the measurements. It is observed that vehicles obstructing the LOS induce an additional average attenuation of about 10 dB in the received signal power. An approach to incorporate the LOS/OLOS model into existing VANET simulators is also provided. Finally, system level VANET simulation results are presented, showing the difference between the LOS/OLOS model and a channel model based on Nakagami-m fading.

  • 2.
    Belyaev, Evgeny
    et al.
    Tampere University of Technology, Tempere, Finland.
    Vinel, Alexey
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Jonsson, Magnus
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Sjöberg, Katrin
    Volvo GTT, Göteborg, Sweden.
    Live video streaming in IEEE 802.11p vehicular networks: Demonstration of an automotive surveillance application2014Inngår i: Computer Communications Workshops (INFOCOM WKSHPS), 2014 IEEE Conference on, Piscataway, United States: IEEE Press, 2014, s. 131-132Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Prospective IEEE 802.11p-enabled automotive video applications are identified. Preliminary experimental results of inter-vehicular live video streaming for surveillance applications are presented. A test-bed for the demonstration of the achievable visual quality under different channel conditions is described.

  • 3.
    Bilstrup, Katrin
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    A preliminary study of wireless body area networks2008Rapport (Annet vitenskapelig)
    Abstract [en]

    The purpose of this preliminary study is to introduce wireless body area networks (WBAN) to the reader but also to give an understanding of what possibilities and challenges there are when using short range wireless communication in this domain. Up to date, there is no standard specifically intended for low-power WBANs thus a developer is referred to use proprietary solutions which could be demanding to compare and choose. This study tries to provide the reader with the knowledge about important parameters in low-power sensor networks. Energy consumption is the really weak part of a wireless sensor network since the transceiver and other hardware equipment still drain batteries. For example the startup time for a transceiver that has been in power-down mode could consume as much as three times the energy

    as compared when sending the actual bits that invoked the transceiver in first place. The actual application must be the one driving the requirements on the communication. However, the application must be designed with for example the startup time in mind. A sensor network is a true cross-layer design problem where many different areas must meet such as hardware designers, application developers and communication people.

  • 4.
    Bilstrup, Katrin
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    A survey regarding wireless communication standards intended for a high-speed vehicle environment2007Rapport (Annet vitenskapelig)
    Abstract [en]

    The high velocities and dynamic conditions that a vehicular environment represents introducenew and demanding challenges in the area of wireless communication. Vehicle Alert System(VAS) is a research project at Halmstad University, Sweden, focusing on reliable wirelessvehicle communication. Typical examples of applications for a vehicle alert system are pre-crash warning, communicating slippery road conditions, emergency vehicle routing etc. InVAS a set of application scenarios have been chosen specifically to illustrate as manyinteresting research aspects of a vehicle alert system as possible. The chosen scenarios includeboth vehicle-to-vehicle and vehicle-to-infrastructure communications. Research is conductedon all layers of the communication stack relevant for a vehicle alert system – application,network, data link and the physical layer. From a communication perspective a vehicle alertsystem is characterized by short event-driven control messages that have to be receivedwithout errors in time. This implies that different coding strategies, diversity andretransmission schemes must be used to achieve correctness and robustness against theimpairments of the wireless channel.

    This survey presents and discusses different wireless communication standards as well asproprietary solutions that are intended especially for a high-speed vehicular environment. Since VAS is aiming for real-time wireless communication, the examined standards will beevaluated accordingly. Real-time communication implies that there is an upper bound on thecommunication delay such that if the data never reaches its intended recipient before a certaindeadline this will have a more or less negative impact on the system performance. One of themost important features of a real-time communication system (and perhaps even more crucialin a wireless high-speed vehicular environment) is the medium access method. If it is notdeterministic (i.e., if there exists no upper bound on the delay before a station gets access tothe wireless channel) it is not possible to give guarantees about meeting the deadlines.All currently existing standards, draft specifications and proprietary solutions with explicitintention for being used in a vehicular environment are covered in this survey. In preparationof this document the standard/draft documents themselves have been studied and forproprietary solutions the respective company’s home pages and in some cases articles havebeen used for collecting information. One of the currently most discussed standards is thedraft IEEE 802.11p which has been thoroughly studied here. It inherits features from theQuality of Service amendment IEEE 802.11e and the physical layer supplement IEEE802.11a. The full protocol suite WAVE, also developed by IEEE, incorporates the 802.11p.Other standards, drafts and proprietary solutions that have been studied are IEEE 802.16,IEEE 802.20, flash-OFDM, national DSCR systems, CALM and IEEE 802.21. These systemsrange from being simple RFID-look-a-like DSRC systems to more advanced centralized WMAN standards. It can be concluded that none of the standards or proprietary solutions described in this surveyis suitable for applications such as those considered in the VAS research project. Within thedifferent standards there certainly are features suitable for a vehicle alert system but nostandard totally fit the requirements of VAS. One lacking feature common for all standardsinvestigated is the ability of providing deterministic medium access for vehicle-to-vehiclecommunication.

  • 5.
    Bilstrup, Katrin
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Böhm, Annette
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Lidström, Kristoffer
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Jonsson, Magnus
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Larsson, Tony
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Strandén, Lars
    SP Technical Research Institute of Sweden, Borås, Sweden.
    Zakizadeh, Hossein
    Volvo Technology Corporation, Göteborg, Sweden .
    Vehicle Alert System2007Inngår i: Proceedings of 14th world congress on intelligent transport system (ITS), 2007, s. 2-9Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The Vehicle Alert System (VAS) project focuses on cooperative alert services based on timely and reliable communication under the challenging circumstances pertaining to a highly mobile vehicular network. Through a cross-layer design, we gain the flexibility needed to adapt the system to the individual requirements of three chosen application scenarios that represent different situations where cooperation between vehicles can make a significant impact. The VAS project is a collaboration involving academic as well as industrial partners and the final stage of the project is a demonstrator that implements results from the research.

  • 6.
    Bilstrup, Katrin
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Böhm, Annette
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Lidström, Kristoffer
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Jonsson, Magnus
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Larsson, Tony
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Report on the Collaboration between CVIS and CERES in the Project Vehicle Alert System (VAS)2009Rapport (Annet vitenskapelig)
    Abstract [en]

    In March 2007, an agreement was made for interchange of experiences between CVIS and the Centre for Research on Embedded Systems (CERES) at Halmstad University in Sweden. The majority of the work relating to this collaboration has been conducted within the CERES project Vehicle Alert System (VAS), aiming to use vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications to provide different types of warning messages. The main focus of the VAS project is on communication and in particular the lower layers of the communication stack are investigated. VAS involves academic researchers from Halmstad University as well as researchers from Volvo Technology, SP Technical Research Institute of Sweden and the company Free2move. This report presents the results of the VAS project, its publications, and other issues of interest both to the CVIS consortium as well as a broader scope.

  • 7.
    Bilstrup, Katrin
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Ström, Erik G.
    Chalmers.
    Medium access control in vehicular networks based on the upcoming IEEE 802.11p standard2008Inngår i: World Congress on Intelligent Transport Systems (ITS), 2008, World Congress on ITS , 2008, s. 12-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper, initial simulations are presented showing that the upcoming IEEE 802.11p standard is not suitable for traffic safety applications requiring reliable, low delay communication between vehicles. The medium access control procedure is one of the most important parts in the design of delay-constrained communication systems, and emerging vehicle safety applications put new stringent demands on timely and reliable delivery of data packets. The medium access procedure used in 802.11p is carrier sense multiple access, which is inherently unsuitable for time-critical data traffic since it is contention-based and cannot provide a finite upper bound on the time to channel access. The simulation results indicate that with IEEE 802.11p, channel access cannot be granted in a manner that is sufficiently predictable to support reliable, low-delay communications between vehicles on a highway.

  • 8.
    Bilstrup, Katrin
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Ström, Erik G.
    Chalmers.
    Bilstrup, Urban
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Evaluation of the IEEE 802.11p MAC method for vehicle-to-vehicle communication2008Inngår i: 68th IEEE Vehicular Technology Conference, 2008. VTC 2008-Fall: IEEE Vehicular Technology Conference (VTC) (2008), Piscataway, N.J.: IEEE Press, 2008, s. 1-5Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper the medium access control (MAC) method of the upcoming vehicular communication standard IEEE 802.11p has been simulated in a highway scenario with periodic broadcast of time-critical packets (so-called heartbeat messages) in a vehicle-to-vehicle situation. The 802.11p MAC method is based on carrier sense multiple access (CSMA) where nodes listen to the wireless channel before sending. If the channel is busy, the node must defer its access and during high utilization periods this could lead to unbounded delays. This well-known property of CSMA is undesirable for time critical communications. The simulation results reveal that a specific node/vehicle is forced to drop over 80% of its heartbeat messages because no channel access was possible before the next message was generated. To overcome this problem, we propose to use self-organizing time division multiple access (STDMA) for real-time data traffic between vehicles. This MAC method is already successfully applied in commercial surveillance applications for ships (AIS) and airplanes (VDL mode 4). Our initial results indicate that STDMA outperforms CSMA for time-critical traffic safety applications in ad hoc vehicular networks.

  • 9.
    Bilstrup, Katrin
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Ström, Erik G.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Bilstrup, Urban
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    On the ability of the 802.11p MAC method and STDMA to support real-time vehicle-to-vehicle communications2009Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. 2009, nr 902414, s. 1-14Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Traffic safety applications using vehicle-to-vehicle (V2V) communication is an emerging and promising area within the intelligent transportation systems (ITS) sphere. Many of these new applications require real-time communication with high reliability, meaning that packets must be successfully delivered before a certain deadline. Applications with early deadlines are expected to require direct V2V communications, and the only standard currently supporting this is the upcoming IEEE 802.11p, included in the wireless access in vehicular environment (WAVE) stack. To meet a real-time deadline, timely and predictable access to the channel is paramount. However, the medium access method used in 802.11p, carrier sense multiple access with collision avoidance (CSMA/CA), does not guarantee channel access before a finite deadline. In this paper, we analyze the communication requirements introduced by traffic safety applications, namely, low delay, reliable, real-time communications.We show by simulation of a simple, but realistic, highway scenario, that vehicles using CSMA/CA can experience unacceptable channel access delays and, therefore, 802.11p does not support real-time communications. In addition, we present a potential remedy for this problem, namely, the use of self-organizing time division multiple access (STDMA). The real-time properties of STDMA are investigated by means of the same highway simulation scenario, with promising results.

  • 10.
    Bilstrup, Katrin
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Ström, Erik G.
    Chalmers, Gothenburg.
    Bilstrup, Urban
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    On the ability of the IEEE 802.11p and STDMA to provide predictable channel access2009Inngår i: Proceedings of the 16th World Congress on Intelligent Transport Systems (ITS), 2009, s. 10-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Emerging traffic safety applications requiring low delay communications will need vehicle ad-hoc networks. The only communication standard currently supporting this is IEEE 802.11p. However, 802.11p uses the medium access method CSMA/CA, which has a major drawback: unbounded worst case channel access delay. We therefore propose an algorithm already in commercial use in the shipping industry: STDMA. With STDMA, nodes always get predictable channel access regardless of the number of competing nodes and the maximum delay is deterministic. In this paper we elaborated with different parameter settings for the two protocols with the aim of improving performance without altering the standards.

     

  • 11.
    Bilstrup, Urban
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Bilstrup, Katrin
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Svensson, Bertil
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Wiberg, Per-Arne
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    The use of clustered wireless multihop networks in industrial settings2007Inngår i: ETFA 2007: IEEE Conference on Emerging Technologies and Factory Automation, Vols 1-3, Piscataway, NJ: IEEE Press, 2007, s. 211-218Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper suggests a cluster collision avoidance mechanism and a dual transceiver architecture to be used in a clustered wireless multihop network. These two contributions make the clustered wireless multihop network the preferred architecture for future industrial wireless networks. The wireless multihop cluster consists of one master and several slaves, where some of the slaves will act as gateways between different clusters. Frequency hopping spread spectrum is used on a cluster level and to avoid frequency collisions between clusters a "neighbor cluster collision avoidance mechanism" is proposed and evaluated through simulations. To break up the dependence between the clusters, introduced by the gateway nodes, each node is equipped with two transceivers. The paper is concluded with a suggestion to use a clustered wireless multihop network with orthogonal hopping sequences for an industrial setting.

  • 12.
    Bilstrup, Urban
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Bilstrup, Katrin
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Svensson, Bertil
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Wiberg, Per-Arne
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Using Dual-Radio Nodes to Enable Quality of Service in a Clustered Wireless Mesh Network2006Inngår i: IEEE Conference on Emerging Technologies and Factory Automation, 2006. ETFA '06, Piscataway, N.J.: IEEE Press, 2006, s. 54-61Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper some well established wireless technologies are merged into a new concept solution for a future industrial wireless mesh network. The suggested clustered wireless mesh network can handle probabilistic quality of service guarantees and is based on a dual-radio node architecture using synchronized frequency hopping spread spectrum Bluetooth radios. The proposed architecture gives a heuristic solution to the inter-cluster scheduling problem of gateway nodes in clustered architectures and breaks up the dependence between the local medium access schedules of adjacent clusters. The dual-radio feature also enables higher network connectivity, implying, for example, that a higher link redundancy can be achieved.

  • 13.
    Bilstrup, Urban
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE).
    Sjöberg, Katrin
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE).
    Svensson, Bertil
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE).
    Wiberg, Per-Arne
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE).
    A fault tolerance test enabling QoS in a Bluetooth piconet2004Konferansepaper (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    An important trend, in personal area networks, is that time critical application becomes more common, e.g., voice over IP, video phone calls, network games. This segment of applications demands for quality of service (QoS) guarantees, to provide the correct functionality. The Bluetooth standard provides an optional interface to support QoS guarantees, but the standard does not suggest any actual implementation. A wireless communication channel is stochastic by nature, providing QoS guarantees with this precondition make traditional deterministic real-time theory obsolete.  In this paper a probabilistic fault tolerance test enabling quality of service guarantees in a Bluetooth piconet is given. The basic Bluetooth network architecture is based on a master-slave configuration, i.e., a point to point connection. More advanced network architectures are possible where up to eight Bluetooth equipped units can be active members of one network (piconet). Furthermore, several piconets can interconnect and form a so called scatternet.

  • 14.
    Bilstrup, Urban
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE).
    Sjöberg, Katrin
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE).
    Svensson, Bertil
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE).
    Wiberg, Per-Arne
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE).
    Capacity limitations in wireless sensor networks2003Inngår i: ETFA 2003: 2003 IEEE Conference on Emerging Technologies and Factory Automation, September 16-19, 2003, Lisbon, Portugal : proceedings, Piscataway, N.J.: IEEE , 2003, s. 529-536, artikkel-id 1247752Konferansepaper (Fagfellevurdert)
    Abstract [en]

    It is expected that wireless sensor network will be used in home automation and industrial manufacturing in the future. The main driving forces for wireless sensor networks are fault tolerance, energy gain and spatial capacity gain. Unfortunately, an often forgotten issue is the capacity limits that the network topology of a wireless sensor network represents. In this paper we identify gains, losses and limitations in a wireless sensor network, using a simplified theoretical network model. Especially, we want to point out the stringent capacity limitations that this simplified network model provide. Where a comparison between the locality of the performed information exchange and the average capacity available for each node is the main contribution.

  • 15.
    Bilstrup, Urban
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE).
    Sjöberg, Katrin
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE).
    Wiberg, Per-Arne
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE).
    A comparison of spatial energy consumption distribution for single- and mulihop wireless network architectures2004Konferansepaper (Fagfellevurdert)
  • 16.
    Lidström, Kristoffer
    et al.
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS).
    Andersson, Johan
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS).
    Bergh, Fredrik
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS).
    Bjäde, Mattias
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS).
    Mak, Spencer
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS).
    Sjöberg, Katrin
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS).
    Halmstad University Grand Cooperative Driving Challenge 2011 Technical Paper2011Rapport (Annet vitenskapelig)
    Abstract [en]

    Traffic congestion is a large and growing problem in many countries due to an ever increasing number of vehicles. Increasing capacity by simply extending the road infrastructure is in many places impossible due to space and cost limitations. Everyday, people spend countless hours in car queues all over the world. The existing road infrastructure must be better utilized to save time and to reduce energy use. By enabling wireless communication between vehicles (V2V) and between vehicles and infrastructure (V2I) the flow of traffic can be better controlled in order to increase not only efficiency but also safety and comfort. Cooperative platooning is one way to increase efficiency by allowing vehicles to form road trains behind a lead vehicle. The Grand Cooperative Driving Challenge (GCDC) is an attempt to move towards a quicker deployment of cooperative platooning. This extended abstract gives an overview of Halmstad University’s team and its technical and organizational approach in preparing a vehicle for the competition.

  • 17.
    Lidström, Kristoffer
    et al.
    Viktoria Institute, Göteborg, Sweden.
    Sjöberg, Katrin
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Holmberg, Ulf
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Andersson, Johan
    Volvo Car Corporation, Göteborg, Sweden.
    Bergh, Fredrik
    Cybercom Group, Stockholm, Sweden.
    Bjäde, Mattias
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE).
    Mak, Spencer
    Innovation Team, Halmstad, Sweden.
    A modular CACC system integration and design2012Inngår i: IEEE transactions on intelligent transportation systems (Print), ISSN 1524-9050, E-ISSN 1558-0016, Vol. 13, nr 3, s. 1050-1061Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper describes the Halmstad University entry in the Grand Cooperative Driving Challenge, which is a competition in vehicle platooning. Cooperative platooning has the potential to improve traffic flow by mitigating shock wave effects, which otherwise may occur in dense traffic. A longitudinal controller that uses information exchanged via wireless communication with other cooperative vehicles to achieve string-stable platooning is developed. The controller is integrated into a production vehicle, together with a positioning system, communication system, and human–machine interface (HMI). A highly modular system architecture enabled rapid development and testing of the various subsystems. In the competition, which took place in May 2011 on a closed-off highway in The Netherlands, the Halmstad University team finished second among nine competing teams.

  • 18.
    Mecklenbräuker, Christoph
    et al.
    Vienna University of Technology, Vienna, Austria.
    Bernadó, Laura
    FTW Forschungszentrum Telekommunikation Wien, Vienna, Austria.
    Klemp, Oliver
    BMW Forschung und Technik, Munich, Germany.
    Kwoczek, Andreas
    Volkswagen AG, Wolsburg, Germany.
    Paier, Alexander
    Vienna University of Technology, Vienna, Austria.
    Schack, Moritz
    Technische Universität Braunschweig, Braunschweig, Germany.
    Sjöberg, Katrin
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Ström, Erik G.
    Chalmers University of Technology, Gothenburg, Sweden.
    Tufvesson, Fredrik
    Lund University, Lund, Sweden.
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Zemen, Thomas
    FTW Forschungszentrum Telekommunikation Wien, Vienna, Austria.
    Vehicle-to-Vehicle Communications2012Inngår i: Pervasive Mobile and Ambient Wireless Communications: Cost Action 2100 / [ed] Roberto Verdone & Alberto Zanella, London: Springer London, 2012, s. 577-608Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    This chapter discusses major results and conclusions from Special Interest Group C bringing together various aspects of mobile to mobile communication from all working groups. Vehicle-to-vehicle communication scenarios are emphasized. Traffic telematics applications are currently under intense research and development for making transportation safer, more efficient, and cleaner. Communication systems which provide “always on” connectivity at data rates between 1 and 10 Mb/s to highly mobile surface traffic (cars and trains) are urgently required for developing traffic telematics applications and services. Currently much attention is given to advanced active safety, but the application area also ranges to improved navigation mechanisms and infotainment services. mobile to mobile communications need to be reliable and trusted: Drivers in cars which are equipped with vehicle to vehicle communications need to rely on the accuracy and timeliness of the exchanged data. Automotive manufacturers, road authorities, broadcast companies, and telecom providers are the key players in the value chain for such future systems. These communication systems provide an extended information horizon to warn the driver or the vehicular systems of potentially dangerous situations in an early phase.

  • 19.
    Sjöberg Bilstrup, Katrin
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Predictable and Scalable Medium Access Control for Vehicular Ad Hoc Networks2009Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This licentiate thesis work investigates two medium access control (MAC) methods, when used in traffic safety applications over vehicular ad hoc networks (VANETs). The MAC methods are carrier sense multiple access (CSMA), as specified by the leading standard for VANETs IEEE 802.11p, and self-organizing time-division multiple access (STDMA) as used by the leading standard for transponders on ships. All vehicles in traffic safety applications periodically broadcast cooperative awareness messages (CAMs). The CAM based data traffic implies requirements on a predictable, fair and scalable medium access mechanism. The investigated performance measures are channel access delay, number of consecutive packet drops and the distance between concurrently transmitting nodes. Performance is evaluated by computer simulations of a highway scenario in which all vehicles broadcast CAMs with different update rates and packet lengths. The obtained results show that nodes in a CSMA system can experience unbounded channel access delays and further that there is a significant difference between the best case and worst case channel access delay that a node could experience. In addition, with CSMA there is a very high probability that several concurrently transmitting nodes are located close to each other. This occurs when nodes start their listening periods at the same time or when nodes choose the same backoff value, which results in nodes starting to transmit at the same time instant. The CSMA algorithm is therefore both unpredictable and unfair besides the fact that it scales badly for broadcasted CAMs. STDMA, on the other hand, will always grant channel access for all packets before a predetermined time, regardless of the number of competing nodes. Therefore, the STDMA algorithm is predictable and fair. STDMA, using parameter settings that have been adapted to the vehicular environment, is shown to outperform CSMA when considering the performance measure distance between concurrently transmitting nodes. In CSMA the distance between concurrent transmissions is random, whereas STDMA uses the side information from the CAMs to properly schedule concurrent transmissions in space. The price paid for the superior performance of STDMA is the required network synchronization through a global navigation satellite system, e.g., GPS. That aside since STDMA was shown to be scalable, predictable and fair; it is an excellent candidate for use in VANETs when complex communication requirements from traffic safety applications should be met.

  • 20.
    Sjöberg, Katrin
    et al.
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Karedal, Johan
    Dept. of Electrical and Information technology, Lund University.
    Moe, Marie
    Q-Free ASA, Trondheim, Norway.
    Kristiansen, Øyvind
    Q-Free ASA, Trondheim, Norway.
    Søråsen, Runar
    Q-Free ASA, Trondheim, Norway.
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Tufvesson, Fredrik
    Dept. of Electrical and Information technology, Lund University.
    Evensen, Knut
    Q-Free ASA, Trondheim, Norway.
    Ström, Erik
    Dept. of Signals and Systems, Chalmers University of Technology.
    Measuring and using the RSSI of IEEE 802.11p2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The scalability of intelligent transport systems (ITS) applications is difficult to test in a field operational test (FOT) due to the high number of ITS equipped vehicles required. Therefore, computer simulations for evaluating different wireless communication technologies for ITS different applications can serve as a complement. In this paper we present results from lab measurements conducted on the CVIS hardware platform equipped with the upcoming standard IEEE 802.11p. We have measured the packet error rate versus the signal-to-noise ratio (SNR) for different packet lengths. This lab measurement is the first step towards an outdoor measurement campaign which also considers interference. The outdoor measurements will then be fed into a computer simulator together with a realistic channel model for evaluating the scalability of VANETs in a highway scenario.

  • 21.
    Sjöberg, Katrin
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Ström, Erik G.
    Chalmers Technical University, Gothenbur, Sweden.
    Delay and interference comparison of CSMA and self-organizing TDMA when used in VANETs2011Inngår i: IWCMC 2011: the 7th International Wireless Communications & Mobile Computing Conference, Istanbul, Turkey, July 4-8, 2011 / [ed] IEEE, New York, NY: IEEE Press, 2011, s. 1488-1793Konferansepaper (Fagfellevurdert)
    Abstract [en]

    IEEE 802.11p is the proposed wireless technology for communication between vehicles in a vehicular ad hoc network (VANET) aiming to increase road traffic safety. In a VANET, the network topology is constantly changing, which requires distributed self-organizing medium access control (MAC) algorithms, but more importantly the number of participating nodes cannot be restricted. This means that MAC algorithms with good scalability are needed, which can fulfill the concurrent requirements on delay and reliability from road traffic safety applications. The MAC method of IEEE 802.11p is a carrier sense multiple access (CSMA) scheme, which scales badly in terms of providing timely channel access for a high number of participating nodes. We therefore propose using another MAC method: selforganizing time division multiple access (STDMA) with which all nodes achieve timely channel access regardless of the number of participating nodes. We evaluate the performance of the two MAC methods in terms of the MAC-to-MAC delay, a measure which captures both the reliability and the delay of the delivered data traffic for a varying number of vehicles. The numerical results reveal that STDMA can support almost error-free transmission with a 100 ms deadline to all receivers within 100 m, while CSMA suffers from packet errors. Moreover, for all considered cases, STDMA offers better reliability than CSMA.

  • 22.
    Sjöberg, Katrin
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Ström, Erik G.
    Chalmers University of Technology.
    How severe is the hidden terminal problem in VANETs when using CSMA and STDMA?2011Inngår i: IEEE Vehicular Technology Conference (VTC Fall) / [ed] IEEE, Piscataway, N.J.: IEEE conference proceedings, 2011, s. 1-5Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The hidden terminal problem is often said to be the major limiting performance factor in vehicular ad hoc networks. In this article we propose a definition of the hidden terminal problem suitable for broadcast transmissions and proceed with a case study to find how the packet reception probability is affected by the presence of hidden terminals. Two different medium access control methods; carrier sense multiple access (CSMA) from IEEE 802.11p and self-organizing time division multiple access (STDMA), are subject of investigation through computer simulations of a highway scenario with a Nakagami fading channel model. The results reveal that the presence of hidden terminals does not significantly affect the performance of the two MAC protocols. STDMA shows a higher packet reception probability for all settings due to the synchronized packet transmissions.

  • 23.
    Sjöberg-Bilstrup, Katrin
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Ström, Erik G.
    Dept. Signals and Systems, Chalmers University of Technology.
    Scalability issues of the MAC methods STDMA and CSMA of IEEE 802.11p when used in VANETs2010Inngår i: 2010 IEEE International Conference on Communications Workshops (ICC), Cape Town, South Africa: IEEE Computer Society, 2010, s. 1-5Konferansepaper (Fagfellevurdert)
    Abstract [en]

     

    Position messages will be the foundation for many emerging traffic safety applications based on wireless communications. These messages contain information about the vehicle’s position, speed, direction, etc. and are broadcasted periodically by each vehicle. The upcoming IEEE 802.11p standard, intended for vehicle unpredictable behavior of its medium access control (MAC) scheme, which imply that traffic safety applications cannot be supported satisfactorily when the network load increases. We study the MAC mechanism within IEEE 802.11p being a carrier sense multiple access (CSMA) algorithm and compare it with a self-organizing time division multiple access (STDMA) scheme when used for broadcasting periodic position messages in a realistic highway scenario. We investigate their scalability in terms of the number of vehicles that the VANET can support using metrics such as channel access delay, probability of concurrent transmissions and interference distance. The results show that STDMA outperforms CSMA of 802.11p even when the network is not saturated.

     

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