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| 2. |
- Balador, Ali, et al.
(författare)
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A Reliable and Efficient Token-Based MAC Protocol for Platooning Applications
- 2016. - 12
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Ingår i: 12th Swedish National Computer Networking Workshop (SNCNW 2016).
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Konferensbidrag (refereegranskat)abstract
- Platooning is both a challenging and rewarding application. Challenging since strict timing and reliability requirements are imposed by the distributed control system required to operate the platoon. Rewarding since considerable fuel reductions are possible. As platooning takes place in a vehicular ad hoc network, the use of IEEE 802.11p is close to mandatory. However, the 802.11p medium access method suffers from packet collisions and random delays. Most ongoing research suggests using TDMA on top of 802.11p as a potential remedy. However, TDMA requires synchronization and is not very flexible if the beacon frequency needs to be updated, the number of platoon members changes, or if retransmissions for increased reliability are required. We therefore suggest a token-passing medium access method where the next token holder is selected based on beacon data age. This has the advantage of allowing beacons to be re-broadcasted in each beacon interval whenever time and bandwidth are available. We show that our token-based method is able to reduce the data age and considerably increase reliability compared to pure 802.11p.
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| 3. |
- Balador, Ali, et al.
(författare)
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A Reliable Token-Based MAC Protocol for Delay Sensitive Platooning Applications
- 2015
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Ingår i: 2015 IEEE 82nd Vehicular Technology Conference (VTC2015-Fall). - [S.l.] : IEEE. - 9781479980918 - 9781479980901
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Konferensbidrag (refereegranskat)abstract
- Platooning is both a challenging and rewarding application. Challenging since strict timing and reliability requirements are imposed by the distributed control system required to operate the platoon. Rewarding since considerable fuel reductions are possible. As platooning takes place in a vehicular ad hoc network, the use of IEEE 802.11p is close to mandatory. However, the 802.11p medium access method suffers from packet collisions and random delays. Most ongoing research suggests using TDMA on top of 802.11p as a potential remedy. However, TDMA requires synchronization and is not very flexible if the beacon frequency needs to be updated, the number of platoon members changes, or if retransmissions for increased reliability are required. We therefore suggest a token-passing medium access method where the next token holder is selected based on beacon data age. This has the advantage of allowing beacons to be re-broadcasted in each beacon interval whenever time and bandwidth are available. We show that our token-based method is able to reduce the data age and considerably increase reliability compared to pure 802.11p. © 2015 IEEE.
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| 4. |
- Balador, Ali, et al.
(författare)
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A Reliable Token-Based MAC Protocol for V2V Communication in Urban VANET
- 2016
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Ingår i: 2016 IEEE 27TH ANNUAL INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR, AND MOBILE RADIO COMMUNICATIONS (PIMRC). - Piscataway : IEEE. - 9781509032549 - 9781509032556 ; , s. 1586-1591
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Konferensbidrag (refereegranskat)abstract
- Safety applications developed for vehicular environments require every vehicle to periodically broadcast its status information (beacon) to all other vehicles, thereby avoiding the risk of car accidents in the road. Due to the high requirements on timing and reliability posed by traffic safety applications, the current IEEE 802.11p standard, which uses a random access Medium Access Control (MAC) protocol, faces difficulties to support timely and reliable data dissemination in vehicular environments where no acknowledgement or RTS/CTS (Request-to-Send/Clear-to-Send) mechanisms are adopted. In this paper, we propose the Dynamic Token-Based MAC (DTB-MAC) protocol. It implements a token passing approach on top of a random access MAC protocol to prevent channel contention as much as possible, thereby improving the reliability of safety message transmissions. Our proposed protocol selects one of the neighbouring nodes as the next transmitter; this selection accounts for the need to avoid beacon lifetime expiration. Therefore, it automatically offers retransmission opportunities to allow vehicles to successfully transmit their beacons before the next beacon is generated whenever time and bandwidth are available. Based on simulation experiments, we show that the DTB-MAC protocol can achieve better performance than IEEE 802.11p in terms of channel utilization and beacon delivery ratio for urban scenarios.
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| 5. |
- Balador, Ali, et al.
(författare)
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An Efficient MAC Protocol for vehicle platooning in automated highway systems
- 2015
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Ingår i: Jornadas Sarteco 2015 JS 2015. - Cordoba, Spain.
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Konferensbidrag (refereegranskat)abstract
- Lately, all the top truck manufacturers are investing considerable resources in the research and development of platooning systems which would allow vehicles to save fuel and improve safety by travelling in a close-following manner. The platooning system requires frequent and reliable vehicle-to-vehicle communications. As platooning takes place in a vehicular ad hoc network, the use of IEEE 802.11p is close to mandatory. However, the 802.11p medium access method suffers from packet collisions and random delays. Most ongoing research suggests using TDMA on top of 802.11p as a potential remedy. However, TDMA requires synchronization and is not very flexible if the beacon frequency needs to be updated, the number of platoon members changes, or if re-transmissions for increased reliability are required. We therefore suggest a token-passing medium access method where the next token holder is selected based on beacon data age. This has the advantage of allowing beacons to be re-broadcasted in each beacon interval whenever time and bandwidth are available. We show that our token-based method is able to reduce the data age and considerably increase reliability considerably compared to pure 802.11p.
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| 6. |
- 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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| 7. |
- Bilstrup, Katrin, et al.
(författare)
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Vehicle Alert System
- 2007
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Ingår i: Proceedings of 14th world congress on intelligent transport system (ITS). ; , s. 2-9
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 8. |
- Böhm, Annette, 1975-, et al.
(författare)
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A Fibre-Optic AWG-Based Real-Time Network and Its Applicability to High-Performance Embedded Computing
- 2005
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Ingår i: 19th International Parallel and Distributed Processing Symposium. - Piscataway, N.J. : IEEE Press. - 0769523129 ; , s. 133b-133b
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Konferensbidrag (refereegranskat)abstract
- In this paper, an architecture and a Medium Access Control (MAC) protocol for a multi-wavelength optical communication network, applicable in short range communication systems like System Area Networks (SANs), are proposed. The main focus lies on guaranteed support for hard and soft real-time traffic. The network is based upon a single-hop star topology with an Arrayed Waveguide Grating (AWG) at its center. Traffic scheduling is centralized in one node (residing together with the AWG in a hub), which communicates through a physical control channel. The AWG's property of spatial wavelength reuse and the combination of fixed-tuned and tunable transceivers in the nodes enable simultaneous control and data transmission. A case study with defined real-time communication requirements in the field of Radar Signal Processing (RSP) was carried out and indicates that the proposed system is very suitable for this kind of application.
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| 9. |
- Böhm, Annette, et al.
(författare)
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A fibre-optic AWG-based real-time network for high-performance embedded computing
- 2004
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Konferensbidrag (refereegranskat)abstract
- In this paper, an architecture and a Medium Access Control (MAC) protocol for a multiwavelength optical communication network, applicable in short range communication systems like System Area Networks (SANs), are proposed. The main focus lies on guaranteed support for hard and soft real-time traffic. The network is based upon a single-hop star topology with an Arrayed Waveguide Grating (AWG) at its center. Traffic scheduling is centralized in one node (residing together with the AWG in a hub), which communicates through a physical control channel. The AWG’s property of spatial wavelength reuse and the combination of fixedtuned and tunable transceivers in the nodes enable simultaneous control and data transmission. A case study with defined real-time communication requirements in the field of Radar Signal Processing (RSP) was carried out and indicates that the proposed system is very suitable for this kind of application.
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| 10. |
- Böhm, Annette, et al.
(författare)
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Adaptive Cooperative Awareness Messaging for Enhanced Overtaking Assistance on Rural Roads
- 2011
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Ingår i: IEEE Vehicular Technology Conference (VTC Fall 2011). - Piscataway, N.J. : IEEE Press. - 9781424483280 ; , s. Article number 609316211-
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Konferensbidrag (refereegranskat)abstract
- Cooperative traffic safety applications such as lane change or overtaking assistance have the potential to reduce the number of road fatalities. Many emerging traffic safety applications are based on IEEE 802.11p and periodic position messages, so-called cooperative awareness messages (CAM) being broadcasted by all vehicles. In Europe, ETSI defines a periodic report rate of 2 Hz for CAMs. Although a high report rate is the key to early hazard detection, the 2 Hz rate has been chosen to avoid congestion in settings where the vehicle density is high, e.g., on major highways and in urban scenarios. However, on rural roads with a limited number of communicating vehicles, a report rate of 2 Hz leads to unnecessary delay in cooperative awareness. By adapting the CAM report rate depending on the specific application and road traffic density, and by making use of the priority levels provided by the 802.11p quality of service mechanism, we show that hazards can be detected earlier and the available bandwidth is used more efficiently, while not overexploiting the network resources.
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