A survey regarding wireless communication standards intended for a high-speed vehicle environment

• 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.

Ämnesord

NATURVETENSKAP  -- Data- och informationsvetenskap -- Datavetenskap (hsv//swe)

NATURAL SCIENCES  -- Computer and Information Sciences -- Computer Sciences (hsv//eng)

Nyckelord

Vehicle Alert System

VAS

wireless communication

Standards

Computer science

Datalogi

Publikations- och innehållstyp

vet (ämneskategori)

rap (ämneskategori)