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  • 1.
    Bilstrup, Katrin
    et al.
    Högskolan i Halmstad, Inbyggda system (CERES).
    Böhm, Annette
    Högskolan i Halmstad, Inbyggda system (CERES).
    Lidström, Kristoffer
    Högskolan i Halmstad, Inbyggda system (CERES).
    Jonsson, Magnus
    Högskolan i Halmstad, Inbyggda system (CERES).
    Larsson, Tony
    Högskolan i Halmstad, Inbyggda system (CERES).
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Inbyggda system (CERES).
    Report on the Collaboration between CVIS and CERES in the Project Vehicle Alert System (VAS)2009Report (Other academic)
    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.

  • 2.
    Bilstrup, Katrin
    et al.
    Högskolan i Halmstad, Inbyggda system (CERES).
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Inbyggda system (CERES).
    Ström, Erik G.
    Chalmers.
    Medium access control in vehicular networks based on the upcoming IEEE 802.11p standard2008In: 15th World Congress on Intelligent Transport Systems and ITS America Annual Meeting 2008, World Congress on ITS , 2008, p. 4155-4167Conference paper (Refereed)
    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.

  • 3.
    Bilstrup, Katrin
    et al.
    Högskolan i Halmstad, Inbyggda system (CERES).
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Inbyggda system (CERES).
    Ström, Erik G.
    Chalmers.
    Bilstrup, Urban
    Högskolan i Halmstad, Inbyggda system (CERES).
    Evaluation of the IEEE 802.11p MAC method for vehicle-to-vehicle communication2008In: 68th IEEE Vehicular Technology Conference, 2008. VTC 2008-Fall: IEEE Vehicular Technology Conference (VTC) (2008), Piscataway, N.J.: IEEE Press , 2008, p. Article number 4657278-Conference paper (Refereed)
    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.

  • 4.
    Bilstrup, Katrin
    et al.
    Högskolan i Halmstad, Inbyggda system (CERES).
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Inbyggda system (CERES).
    Ström, Erik G.
    Högskolan i Halmstad, Inbyggda system (CERES).
    Bilstrup, Urban
    Högskolan i Halmstad, Inbyggda system (CERES).
    On the ability of the 802.11p MAC method and STDMA to support real-time vehicle-to-vehicle communications2009In: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. 2009, no 902414, p. 1-14Article in journal (Refereed)
    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.

  • 5.
    Bilstrup, Katrin
    et al.
    Högskolan i Halmstad, Inbyggda system (CERES).
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Inbyggda system (CERES).
    Ström, Erik G.
    Chalmers, Gothenburg.
    Bilstrup, Urban
    Högskolan i Halmstad, Inbyggda system (CERES).
    On the ability of the IEEE 802.11p and STDMA to provide predictable channel access2009In: Proceedings of the 16th World Congress on Intelligent Transport Systems (ITS), 2009, p. 10-Conference paper (Refereed)
    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.

     

  • 6.
    Dabcevic, Kresimir
    Mälardalen University, School of Innovation, Design and Engineering.
    Evaluation of Software Defined Radio platform with respect to implementation of 802.15.4 Zigbee2011Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    With the development of powerful computational resources such as Digital Signal Processors and Field Programmable Gate Arrays, It has become possible to utilize many radio functions via software. This is the main concept of an up-and-coming technology of Software Defined Radio.

    In the Thesis, a number of platforms for implementation of Software Defined Radio has been evaluated. Platform that proved to be most suitable for the project was Ettus’ USRP N210. Using the platform, implementation of 802.15.4 Zigbee’s physical layer was done, where experiments whose outputs can later be used to compare performance with respect to "hardware radios" were performed.

  • 7.
    Ekström, Martin
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Bergblomma, Marcus
    Mälardalen University, School of Innovation, Design and Engineering.
    Lindén, Maria
    Mälardalen University, School of Innovation, Design and Engineering.
    Björkman, Mats
    Mälardalen University, School of Innovation, Design and Engineering.
    Ekström, Mikael
    Edith Cowan University, Bunbury, Australia.
    A Bluetooth Radio Energy Consumption Model for Low Duty-Cycle Applications2012In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 61, no 3, p. 609-617Article in journal (Refereed)
    Abstract [en]

    This paper presents a realistic model of the radio energy consumption for Bluetooth-equipped sensor nodes used in a low-duty-cycle network. The model is based on empirical energy consumption measurements of Bluetooth modules. This model will give users the possibility to optimize their radio communication with respect to energy consumption while sustaining the data rate. This paper shows that transmission power cannot always be directly related to energy consumption. Measurements indicate that, when the transmission power ranges from $-$5 to $+$10 dBm, the difference in consumed energy can be detected for each transmission peak in the sniff peak. However, the change is negligible for the overall energy consumption. The nonlinear behavior of the idle state for both master and slave when increasing the interval and number of attempts is presented. The energy consumption for a master node is in direct relation to the number of slaves and will increase by approximately 50% of the consumption of one slave per additional slave, regardless of the radio setting.

  • 8.
    Hassani, Abtin
    Mälardalen University, School of Innovation, Design and Engineering.
    Designing a fault tolerant and secure network core for inter-organization communication2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Service providers which provide services within customers’ networks often deal with the issue of needing to use a large number of VPN accounts and RSA tokens to access customers’ networks. One service provider (SP) has solved this by setting up an inter-organizational communication network (IOCN) to facilitate access to customer places systems. This system has out grown its original setup.  Research on network architectures is abundant but there is very limited research focusing on IOCNs. The aim of this thesis has been to contribute to the lack of that research by intending to redesign the above mentioned IOCN with focus on ensuring network security and fault tolerance. This was done by analyzing the existing IOCN, evaluating its flaws with regards to network security and fault tolerance and finally suggesting a new setup based on the original infrastructure. The solution has been generalized to be adaptable to the needs of any service provider. The infrastructure has been setup with a cascading firewall structure increasing security by using generalized rules on the outer firewalls and specifying rules further in to the network.

  • 9.
    Henriksson, Johannes
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Magnusson, Alexander
    Mälardalen University, School of Innovation, Design and Engineering.
    Impact of using cloud-based SDNcontrollers on the networkperformance2019Independent thesis Basic level (university diploma), 180 HE creditsStudent thesis
    Abstract [en]

    Software-Defined Networking (SDN) is a network architecture that differs from traditionalnetwork planes. SDN has tree layers: infrastructure, controller, and application. Thegoal of SDN is to simplify management of larger networks by centralizing control into thecontroller layer instead of having it in the infrastructure. Given the known advantages ofSDN networks, and the flexibility of cloud computing. We are interested if this combinationof SDN and cloud services affects network performance, and what affect the cloud providersphysical location have on the network performance. These points are important whenSDN becomes more popular in enterprise networks. This seems like a logical next step inSDN, centralizing branch networks into one cloud-based SDN controller. These questionswere created with a literature studies and answered with an experimentation method. Theexperiments consist of two network topologies both locally hosted SDN (baseline) and cloudhosted SDN. The topology used Zodiac FX switches and Linux hosts. The following metricswas measured: throughput, latency, jitter, packet loss, and time to add new hosts. Theconclusion is that SDN as a cloud service is possible and does not significantly affect networkperformance. One limitation with this thesis was the hardware, resulting in big fluctuationin throughput and packet loss.

  • 10.
    Huu, Tung Pham
    et al.
    NUCE, Fac Informat Technol, 55 Giai Phong Rd, Hanoi, Vietnam.
    Quach, Truong Xuan
    TNU Univ Informat & Commun Technol, Ho Chi Minh City, Vietnam.
    Tran, Hung Vinh
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Zepernick, Hans-Jurgen
    Blekinge Inst Technol, Karlskrona, Sweden..
    Sibomana, Louis
    Univ Rwanda, Kigali, Rwanda..
    On Proactive Attacks for Coping With Cooperative Attacks in Relay Networks2017In: 2017 23RD ASIA-PACIFIC CONFERENCE ON COMMUNICATIONS (APCC): BRIDGING THE METROPOLITAN AND THE REMOTE, IEEE , 2017, p. 220-225Conference paper (Refereed)
    Abstract [en]

    Cooperative communications in which relays assist the transmission of signals from source to destination offer extended radio coverage and improved link reliable. However, transmitting signals with the help of a relay network may also open additional avenues for eavesdropper to overhear confidential information. Further, as jammers and eavesdroppers may cooperate to attack the relay network, offering secure communications becomes a challenging problem. To cope and reduce the effect of such cooperative attacks, we propose a proactive attack scheme in which the legitimate users generate jamming signals in an attempt to counteract such hostile cooperative attacks. In order to assess the security performance of the proactive attack scheme compared to a non-protection scheme, an analytical expression of the secrecy outage probability is derived. Numerical results for different system settings are provided showing that the proactive attack scheme can indeed significantly improve the security performance of the considered relay networks.

  • 11.
    Kunert, Kristina
    et al.
    Högskolan i Halmstad, Centrum för forskning om inbyggda system (CERES).
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Centrum för forskning om inbyggda system (CERES).
    Jonsson, Magnus
    Högskolan i Halmstad, Centrum för forskning om inbyggda system (CERES).
    Enhancing reliability in IEEE 802.11 based real-time networks through transport layer retransmissions2010In: 2010 International Symposium on Industrial Embedded Systems (SIES), 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.

     

  • 12.
    Kunert, Kristina
    et al.
    Högskolan i Halmstad, Centrum för forskning om inbyggda system (CERES).
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Centrum för forskning om inbyggda system (CERES).
    Jonsson, Magnus
    Högskolan i Halmstad, Centrum för forskning om inbyggda system (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), 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.

  • 13.
    Lööf, Mattias
    Mälardalen University, School of Innovation, Design and Engineering.
    Morgondagens Nätverksadministratör2018Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Datornätverken håller på att förändras i grunden där det traditionella sättet med enheter som konfigureras en och en byts mot ett mer automatiserat sätt. Denna nya typ av nätverk benämns ofta ”Software Defined Network (SDN)” och använder sig av en centraliserad Controller som styr nätverket. För automatisering och användning av applikationer inom SDN används Application Programming Interface(API).Denna nya typ av nätverk förändrar kraven som ställs på nätverksadministratörer och skapar nya möjligheter. Några av dessa möjligheter skapas genom öppnande av API:er där applikationer nu kan integreras in i nätverket. Detta gör att nätverksadministratörer även behöver ha kunskap kring API:er och förstå vilka möjligheter de skapar i nätverket. Rapportens syfte var att redogöra för dessa genom följande frågeställningar:

    1. Vilken kompetens kommer att krävas av morgondagens nätverksadministratör (två- till fyra-års sikt)

    2. Hur kommer det programmerbara (API) nätverket att förändra sättet att etablera nya tjänster/applikationer i företagens nätverk?

    3. Hur kan dessa applikationer implementeras på ett nytt och automatiserat sätt?

    För att besvara frågeställningarna användes en exempelteknik ”Cisco Software Defined Access (SDA)” som är en ny SDN-lösning släppt på marknaden under 2017.Resultatet från frågeställning ett visade att kunskap kring nya protokoll som implementeras för att lösa utmaningen kring segmentering, mobilitet och säkerhet i nätverk blir viktigt. Exempel på detta var protokollen LISP och VXLAN som tillsammans med ett overlay-lager skapar dessa möjligheter. Resultatet visade även att kunskap kring hur Northbound och Southbound Interfaces används för styrande av nätverksenheterna och integration mellan applikationer blir en viktig kompetens.Resultatet för frågeställning två visade hur API:er förenklar utvecklingen av tredjeparts applikationer, något som gör att användningen och utvecklingen av applikationer kommer öka i allt snabbare takt. Slutligen visade resultatet exempel på hur en brandväggsapplikation kan förenkla och effektivisera arbetet för en nätverksadministratör.

  • 14.
    Morsi Mahmod, Mohamed
    et al.
    University of Twente, Sweden.
    Khalil, Issam
    Ericsson AB, Branch Office Sudan, Sudan.
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Sweden.
    Nygren, Niclas
    Volvo Technology Corporation, Transport, Information and Communication, Sweden.
    Wireless strategies for future and emerging ITS applications2008In: 15th World Congress on Intelligent Transport Systems: New York, USA, November 16-20, 2008 : ITS connections, saving time, saving lives, New York: World Congress on Intelligent Transport Systems (ITS) , 2008, p. 12-Conference paper (Refereed)
    Abstract [en]

    Within the Intelligent Transportation Systems (ITS) field, many applications of a diverse nature are considered and thus their communication requirements differ significantly. This makes it difficult for one wireless carrier to support all or most of these applications. Therefore, we have complied a list of communication requirements for future ITS applications and used it to analyze different ITS applications as well as different wireless carriers. Accordingly, the applications can be grouped into different requirements profiles with recommended wireless carriers assigned to each profile. The concept of profiling can also be used to classify the applications according to their non-technical requirements and hence accelerate their future deployment by encouraging involved stakeholders to make the most common requirements available. It can also be useful when developing a roadmap for deployment of future ITS applications defining which application will most likely be implemented first.

  • 15.
    Sjöberg, Katrin
    et al.
    Högskolan i Halmstad, 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, 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 802.11p2010Conference paper (Refereed)
    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.

  • 16.
    Sjöberg, Katrin
    et al.
    Högskolan i Halmstad, Inbyggda system (CERES).
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Inbyggda system (CERES).
    Ström, Erik G.
    Chalmers Technical University, Gothenbur, Sweden.
    Delay and interference comparison of CSMA and self-organizing TDMA when used in VANETs2011In: IWCMC 2011: IWCMC 2011 - 7th International Wireless Communications and Mobile Computing Conference / [ed] IEEE, New York, NY: IEEE Press , 2011, p. 1488-1493Conference paper (Refereed)
    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.

  • 17.
    Sjöberg-Bilstrup, Katrin
    et al.
    Högskolan i Halmstad, Inbyggda system (CERES).
    Uhlemann, Elisabeth
    Högskolan i Halmstad, 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 VANETs2010In: 2010 IEEE International Conference on Communications Workshops (ICC), 2010, p. Article number 5503941-Conference paper (Refereed)
    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 saturate

     

  • 18.
    Strandén, Lars
    et al.
    SP Technical Research Institute of Sweden, Borås, Sweden.
    Uhlemann, Elisabeth
    Volvo Technology Corporation, Gothenburg, Sweden.
    Ström, Erik G.
    Chalmers University of Technology, Gothenburg, Sweden.
    State of the art survey of wireless vehicular communication projects2008In: 15th World Congress on Intelligent Transport Systems: New York, November 16-20, 2008 : proceedings : ITS connections: saving time, saving lives, World Congress on Intelligent Transport Systems (ITS) , 2008, p. 10-Conference paper (Refereed)
    Abstract [en]

    In this paper the results of a state of the art survey, using publicly available information, are presented. The scope of the survey concerns projects that include wireless communication vehicle-to-vehicle and vehicle-to-infrastructure. Since there is a vast amount of information available, a specific methodology has to be developed and applied. This paper presents such a methodology which is based on a matrix representation that enables the definition of specific metrics. These metrics can then be used for further evaluation. The objectives of this work are threefold; to gather relevant project information, to define and apply a methodology for handling this information, and to compare and draw some general conclusions about the nature of projects carried out in Europe, USA and Japan.

  • 19.
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Inbyggda system (CERES).
    Communication requirements of emerging cooperative driving systems2011In: Digest of Technical Papers - IEEE International Conference on Consumer Electronics / [ed] Institute of Electrical and Electronics Engineers, Piscataway, N.J.: IEEE Computer Society , 2011, p. 281-282Conference paper (Refereed)
    Abstract [en]

    Traffic safety applications relying on cooperative systems are currently being considered by several research projects worldwide. An important question is if existing wireless technologies can meet the communication requirements from this emerging field of applications? Part of the answer to this question is that the communication requirements depend on what is actually communicated and how this information is used by and presented to the driver. The data traffic from realizations based on "cooperative awareness" or on "hazard warnings" are very different. This article discusses the communication requirements of some typical traffic safety applications and how these requirements are affected by different realizations.

  • 20.
    Uhlemann, Elisabeth
    et al.
    Högskolan i Halmstad, Inbyggda system (CERES).
    Nygren, Niclas
    Volvo Technology, Sweden.
    Cooperative systems for traffic safety: Will existing wireless access technologies meet the communications requirements?2009In: Proceedings of the 16th World Congress on Intelligent Transport Systems (ITS), Stockholm: World Congress on Intelligent Transport Systems (ITS) , 2009, p. 8-Conference paper (Refereed)
    Abstract [en]

    Traffic safety applications relying on cooperative systems are currently being considered by several research projects worldwide. An important question is if existing wireless technologies can meet the communication requirements from this emerging field ofvapplications? Part of the answer to the question is that the communication requirements depend on implementation. The data traffic from realizations based on “cooperative awareness” or on “hazard warnings” are very different. This article discusses the communication requirements of some typical traffic safety applications, how these requirements are affected by different realizations and finally what is required from a wireless access technology to support these applications.

  • 21.
    Uhlemann, Elisabeth
    et al.
    Högskolan i Halmstad, Inbyggda system (CERES).
    Willig, Andreas
    Technical University of Berlin.
    Hard decision packet combining methods for industrial wireless relay networks2008In: Second International Conference on Communications and Electronics, 2008. ICCE 2008, Piscataway, N.J.: IEEE Press , 2008, p. 104-108Conference paper (Refereed)
    Abstract [en]

    We consider wireless relay networks for use in industrial applications with strict requirements on both reliable and timely communications. In most cases commercially available transceivers must be used, which implies that only hard decision detector outputs are available. Since relay networks typically use retransmissions of erroneous packets, packet combining methods have the potential to increase the information reliability without excessive delay. We evaluate three different hard decision packet combining methods for different placement of the source, the relay node and the destination. Packet combining can in general be improved with knowledge of the current channel state information, which, however, is often not available. In this paper we find a packet combining method which does not use channel state information but which delivers similar performance as the scheme that has knowledge of the channel state.

  • 22.
    Uhlemann, Elisabeth
    et al.
    Högskolan i Halmstad, Inbyggda system (CERES).
    Willig, Andreas
    Technical University of Berlin.
    Joint design of relay and packet combining schemes for wireless industrial networks2008In: IEEE Vehicular Technology Conference 2008, IEEE Press , 2008, p. 2441-2445Conference paper (Refereed)
    Abstract [en]

    Wireless industrial networks differ in many respects from other types of wireless networks. In particular, since many applications impose tight real-time and reliability requirements at the same time, and packet sizes tend to be small. In this paper we design a simple and practically implementable protocol in which relaying and packet combining work together to improve the probability that packets are delivered within a prescribed deadline over fading channels. The results indicate that such a combination can be fruitfully employed in wireless industrial networks.

  • 23.
    Wang, W.
    et al.
    Computer Science Department, University of Pittsburgh, Pittsburgh, PA, United States.
    Mosse, D.
    Computer Science Department, University of Pittsburgh, Pittsburgh, PA, United States.
    Papadopoulos, Alessandro
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Packet priority assignment for wireless control systems of multiple physical systems2019In: Proceedings - 2019 IEEE 22nd International Symposium on Real-Time Distributed Computing, ISORC 2019, Institute of Electrical and Electronics Engineers Inc. , 2019, p. 143-150Conference paper (Refereed)
    Abstract [en]

    Wireless control systems (WCSs) have gained much attention lately, due to their easy deployment and flexibility compared to wired control systems. However, this comes at the cost of possibly increased network delay and packet losses, that can significantly impact the control system performance, and possibly its stability. Such problems become even more relevant if the network is shared among different control systems, and thus becomes a scarce resource, like in Industrial Internet of Things applications. In this paper, we describe how to assign packet priorities dynamically when there are many physical systems sharing a given network, aiming at minimizing the performance degradation of the WCS. Towards that, we present a network model including both delay and packet losses, both of which are very important for the control system performance. Our solution is evaluated over two different use cases to show the generality of the approach: the WCS for a set of inverted pendula, and the WCS for small modular reactors in a nuclear power plant. The results show that the proposed approach allows for a more stable performance even in presence of highly nonlinear systems, sensitive to time-varying delays, as well as in presence of high network interference.

  • 24.
    Willig, Andreas
    et al.
    Technische Universitt Berlin, Berlin, Germany.
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Inbyggda system (CERES).
    PRIOREL-COMB: A protocol framework supporting relaying and packet combining forwireless industrial networking2008In: WFCS 2008: 2008 IEEE International Workshop on Factory Communication Systems : proceedings : May 21st-23rd, 2008, Steigenberger Hotel de Saxe, Dresden, Germany / [ed] Gianluca Cena and Françoise Simonot-Lion, Piscataway, NJ: IEEE Press , 2008, p. 45-54Conference paper (Refereed)
    Abstract [en]

    The PRIOREL-COMB framework presented here integrates support for relaying and packet combining into wireless industrial networks. The selection of suitable relay nodes is made using distributed algorithms which includes different eligibility tests as well as different priority assignments. The framework improves performance in terms of probability to successfully deliver packets before their deadline and it can be implemented on top of commercial transceivers without modification of the physical layer. This class of protocols will therefore be a valuable addition to future wireless industrial communication systems.

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