Car2x

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Symbolic image of several typical Car2x communication lines

Car2x (pronounced “Car to x”) is a technology developed in the 2010s in which vehicles communicate with their environment (“x”), but also with each other. The exchange of data between neighboring vehicles is a special case of Car2x and is called Car2Car , often called Vehicle2Vehicle or V2V communication in the Anglo-Saxon language . With Car2x, transmission is possible in both directions, i.e. from the vehicle to the environment and vice versa. With Car2x, no image and video data are processed, but sensor data in tabular form, only a few kilobytes in size per transmission . Car2x is intended to increase traffic safety, lead to energy savings and improve the efficiency of transport.

Transmission technology and use cases

There are basically two types of transmission for Car2x. The one with low latency (i.e. without a noticeable time delay), but only a few hundred meters range, is the WLAN standard for cars WLANp. A typical application would be vehicles that are approaching an intersection with a traffic light, whereupon the traffic light switches ad hoc and disrupts the flow of traffic less. The second type of transmission takes place via mobile communications . The participating vehicles must have SIM cards installed for this. If there is no network reception, the on-board electronics save the data and send it with the previous time stamp as soon as it is online again. The transmission time between the sender, the cloud and the recipient is generally less than 3 seconds. One application is a mobile construction site in confusing terrain, which reports its position on the screens of all vehicles driving within a radius of 4 kilometers.

Car2x technology was made possible by two factors: increasingly dense data networks and more and more sensors in the vehicle. If black ice suddenly sets in , a car can use the ESP stabilization system to warn other drivers without the driver noticing. Salt spreading services statistically determine from such danger spots not only streets that they have to serve quickly, but also areas where they tend to spread too much salt. A damaged vehicle automatically sends an eCall , which not only the police but also nearby cars receive via Car2x. The rain sensor in combination with a high windshield wiper frequency sends the relevant data to everyone in the area. Manual input by the driver is also possible, for example if he sees horses near the motorway or in fog.

Since the end of the 2010s, Car2x has been offered in both versions (WLAN and mobile communications) as an additional package for almost all types of cars. The field tests were largely successful. According to the manufacturers, personal data is never transmitted. The systems try to protect themselves against misuse, such as willful false reports from a driver, using plausibility algorithms in the data-processing cloud.

Car2x is often mentioned in the same breath as autonomous driving , but has little to do with it: Autonomous cars require a large amount of environmental data, where the small amounts of data from Car2x play a minor role. Car2x, for example, does not transmit any videos, while autonomous driving is heavily based on videos and other imaging processes.

The Car2x communication strengthens safety systems such as anti-collision , lane departure warning and monitoring of the dead angle , collision warning (with brake lights ), intersection assistant , emergency vehicle detectors , construction Warner and opportunities for the platooning (column formation).

  • Right of way for vehicles
    with special rights

  • Lane narrowing

  • Brake warning

  • Toll station report

A report by the US National Highway Traffic Safety Administration (NHTSA) lists the applications that are planned as part of US European Standardization ( ETSI ). Earlier application examples focused on efficiency and road safety.

Technology overview

802.11p

Dedicated short-range communication (DSRC). The original form uses WLAN technology between the vehicles that belong to the vehicle ad hoc network of the participants within the range of the WLAN of the other participants. Since no infrastructure is required, this technology is suitable for contributing to traffic safety in structurally weak areas. WLAN is suitable for this application due to its short delay times due to the short control sequences and therefore the small amount of data. The radio technology is defined for the USA in the " IEEE 802.11 " rules. In Europe as ITS-G5.

3GPP (C-V2X)

Other Car2x solutions use cellular networks called Cellular V2X (or C-V2X). This makes it easier to distinguish it from other technologies. Numerous industrial organizations, such as the 5G Automotive Association (5GAA), advertise the use of C-V2X because it should have certain advantages over the WLAN-based standard. These advantages C-V2X was originally defined as LTE version 14 of the 3GPP .

In addition to the advantages mentioned, various problems can also be observed. For example, the non-coordinated channel access "semi persistent scheduling" in the C-V2X network requires more complex and error-prone algorithms than the already proven CSMA / CA which is used by the DSRC-based Car2X version.

With version 16, the functionality was expanded to support the 5G standard . A characteristic of the C-V2X is that it is designed to be upwards and downwards compatible, combined with higher costs.

In the vehicle itself, networking takes place via the so-called PC5 interface. In addition to communication via the PC5 interface, the C-V2X enables regular communication via the Uu interface to the base station of the radio network.

Applications

The VW Golf 8 was the first car for V2X to be equipped with NXP technology and tested by users.

It uses the 802.11p based DSRC technology due to the more available test systems.

Associations

See also

Web links

Remarks

  • WIRELESS INTERNET ACCESS
  1. ↑ WLAN transmits CAM (Cooperative Awareness Messages), Decentralized Environmental Notification Messages (DENM) or Basic Safety Message (BSM)
  • LTE
  1. ↑ The designation PC5 refers to a reference point that is used to communicate with other user devices. In the In 3GPP RAN specification this is referred to as a sidelink. the original purpose of this point was to enable authorities to use LTE in the event of a disaster.
  2. ↑ Uu is an interface protocol

Individual evidence

  1. ↑ Kim Tingley: How to Make Cars Cooperate . In: The New York Times . November 9, 2017, ISSN  0362-4331 ( nytimes.com [accessed February 15, 2020]).
  2. ↑ C-V2X paves the way to 5G for autonomous driving. Retrieved August 19, 2018 .
  3. ↑ WLANp. Retrieved February 15, 2020 .
  4. ^ NHTSA: Vehicle-to-Vehicle Communications: Readiness of V2V Technology for Application. (PDF) Retrieved August 20, 2018 (English).
  5. ↑ ETSI TR 102638 Intelligent Transport Systems (ITS); Vehicular communications; Basic Set of Applications; Definition. (PDF) Retrieved August 20, 2018 (English).
  6. ↑ SAE J2945 / x family of standards. (No longer available online.) Archived from the original ; accessed on August 20, 2018 .
  7. ↑ Xiao-Feng Xie, Zun-Jing Wang: SIV-DSS: Smart in-vehicle decision support system for driving at signalized intersections with V2I communication . In: Transportation Research Part C . tape 90 , 2018, p. 181–197 , doi : 10.1016 / j.trc.2018.03.008 .
  8. ↑ EN 302 663 Intelligent Transport Systems (ITS); Access layer specification for Intelligent Transport Systems operating in the 5 GHz frequency band. (PDF) Retrieved August 20, 2018 (English).
  9. ↑ The Case for Cellular V2X for Safety and Cooperative Driving. (PDF) Retrieved August 20, 2018 .
  10. ↑ So-Yi Jung, Hye-Rim Cheon, Jae-Hyun Kim: Reducing Consecutive Collisions in Sensing Based Semi Persistent Scheduling for Cellular-V2X . Ed .: 2019 IEEE 90th Vehicular Technology Conference (VTC2019 case): proceedings: Honolulu, Hawaii, USA, 22-25 September 2019. Piscataway, NJ, ISBN 978-1-72811-220-6 .
  11. ↑ Dino Flore: Initial Cellular V2X standard completed. September 26, 2016, accessed August 20, 2018 .
  12. ↑ LTE V2X Communication - Scenario and OAI Roadmap. (PDF) p. 6 , accessed on August 20, 2018 (English).
  13. ^ Uu interface protocol stack. Accessed August 20, 2018 .
  14. ↑ Sam Abue lsamid: Volkswagen Adds 'Vehicle-To-Everything' Communications To Revamped Golf With NXP Chips. Forbes, accessed March 31, 2020 .
  15. ↑ Elektronik automotive (ed.): ADAC tests C2X with pWLAN . April 2020.
  16. ↑ V2X Testing Solutions. In: SEA Datentechnik GmbH. Retrieved August 28, 2020 .