| 1. |
- Bilstrup, Katrin, et al.
(författare)
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Evaluation of the IEEE 802.11p MAC method for vehicle-to-vehicle communication
- 2008
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Ingår i: 68th IEEE Vehicular Technology Conference, 2008. VTC 2008-Fall. - Piscataway, N.J. : IEEE Press. - 9781424417216 ; , s. 1-5
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 2. |
- Bilstrup, Katrin, et al.
(författare)
-
Medium access control in vehicular networks based on the upcoming IEEE 802.11p standard
- 2008
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Ingår i: 15th World Congress on Intelligent Transport Systems and ITS America Annual Meeting 2008. - : World Congress on ITS. - 9781615677566 ; , s. 4155-4167, s. 12-
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 3. |
- Bilstrup, Katrin, et al.
(författare)
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On the ability of the 802.11p MAC method and STDMA to support real-time vehicle-to-vehicle communications
- 2009
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Ingår i: EURASIP Journal on Wireless Communications and Networking. - New York : Hindawi Publishing Corporation. - 1687-1472 .- 1687-1499. ; 2009:902414, s. 1-14
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 4. |
- Bilstrup, Katrin, 1972, et al.
(författare)
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On the ability of the IEEE 802.11p and STDMA to provide predictable channel access
- 2009
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Ingår i: Proceedings of the 16<sup>th</sup> World Congress on Intelligent Transport Systems (ITS). ; , s. 10-
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 5. |
- Bilstrup, Katrin, et al.
(författare)
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Report on the Collaboration between CVIS and CERES in the Project Vehicle Alert System (VAS)
- 2009
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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| 6. |
- Lerchbaumer, Peter, et al.
(författare)
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Test environment design for wireless vehicle communications
- 2007
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Ingår i: The 66th IEEE Vehicular Technology Conference, 2007. VTC-2007 Fall. - Piscataway, NJ : IEEE Press. - 9781424402632 ; , s. 2214-2218
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Konferensbidrag (refereegranskat)abstract
- The integration of new wireless technologies with vehicle computing systems has opened the doors for new fields of applications such as intelligent transportation systems. Vehicular ad hoc networks emerge as the technical basis in solutions aiming to improve road safety and efficiency as well as driving comfort. This paper discusses different factors that influence the performance of wireless vehicle communication systems and proposes a general design for the construction of a test environment for these systems. A comprehensive list of different parameters that affect the system performance is compiled. Next, these parameters are analyzed and quantified to serve as guidelines when establishing and designing components of a suitable test environment. This test environment should provide a platform that enables researchers and engineers to identify possible bottlenecks in the network functionality as well as allowing test, assessment and verification of as many of the relevant parameters involved in the ad hoc communication as possible.
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| 7. |
- Miorandi, Daniele, et al.
(författare)
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Guest editorial : Special section on wireless technologies in factory and industrial automation – part I
- 2007
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Ingår i: IEEE Transactions on Industrial Informatics. - Piscataway, NJ : IEEE Computer Society. - 1941-0050. ; 3:2, s. 95-98
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The three papers in this special section focus on wireless technologies in factory and industrial automation. The papers which appear in this second part cover everything from protocol design and evaluation to the design and assessment of system-level solutions for wireless sensor networks in industrial automation.
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| 8. |
- Miorandi, Daniele, et al.
(författare)
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Guest editorial : Special section on wireless technologies in factory and industrial automation – part II
- 2007
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Ingår i: IEEE Transactions on Industrial Informatics. - Piscataway, NJ : IEEE Computer Society. - 1941-0050. ; 3:3, s. 189-190
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The three papers in this special section focus on wireless technologies in factory and industrial automation. The papers which appear in this second part cover everything from protocol design and evaluation to the design and assessment of system-level solutions for wireless sensor networks in industrial automation.
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| 9. |
- Morsi Mahmod, Mohamed, et al.
(författare)
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Wireless strategies for future and emerging ITS applications
- 2008
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Ingår i: 15th World Congress on Intelligent Transport Systems. - New York : World Congress on Intelligent Transport Systems (ITS). ; , s. 12-
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 10. |
- Rasmussen, Lars Kildehöj, et al.
(författare)
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Concatenated systems and cross-layer design
- 2006
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Ingår i: Proceedings, 7th Australian Communications Theory Workshop 2006. - Piscataway, NJ : IEEE Press. - 1424402131 ; , s. 80-86
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Konferensbidrag (refereegranskat)abstract
- With high data rate wireless communications networks, new applications relying on high quality audio, video or control become viable. Examples of such applications are remote tele-medicine, collision avoidance systems, and audio/video entertainment at CD/DVD quality. These applications all demand high data rates, but have different quality-of-service (QoS) requirements in terms of reliability and latency. Currently, mobile communications networks have only limited provisions for QoS implementation and control. The conventional functionality separation in network design may be inhibiting effective implementation of guaranteed QoS. In this paper, we propose and review a system design paradigm based on concatenated system models and iterative signal processing. The novelty of the paradigm is to propagate methodologies of physical layer design across disciplinary boundaries within wireless network design in a bottom-up cross-layer approach. The paper is tutorial in nature, promoting the new view through presenting a series of examples of successful application of concatenated systems design from the physical and link layers. The purpose of the paper is to inspire new research directions.
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