IEEE 802.11p is an approved amendment to the IEEE 802.11 standard to add wireless access in vehicular environments (WAVE). It defines enhancements to 802.11 (the basis of products marketed as Wi-Fi) required to support Intelligent Transportation Systems (ITS) applications. This includes data exchange between high-speed vehicles and between the vehicles and the roadside infrastructure in the licensed ITS band of 5.9 GHz (5.85-5.925 GHz). IEEE 1609 is a higher layer standard based on the IEEE 802.11p.
802.11p will be used as the groundwork for Dedicated Short Range Communications (DSRC), a U.S. Department of Transportation project based on the ISO Communications, Air-interface, Long and Medium range (CALM) architecture standard looking at vehicle-based communication networks, particularly for applications such as toll collection, vehicle safety services, and commerce transactions via cars. The ultimate vision is a nationwide network that enables communications between vehicles and roadside access points or other vehicles. This work builds on its predecessor ASTM E2213-03.
In Europe, 802.11p is used as a basis for the ITS-G5 standard, supporting the geonetworking protocol for vehicle to vehicle and vehicle to infrastructure communication. ITS G5 and Geonetworking is being standardised by ETSI ITS
Some amendment added to IEEE 802.11
Transmissions outside the context of a BSS
As the communication link between the vehicles and the roadside infrastructure might exist for only a short amount of time, the IEEE 802.11p amendment defines a way to exchange data through that link without the need to establish a BSS, and thus, without the need to wait for the association and authentication procedures to complete before exchanging data. For that purpose, IEEE 802.11p enabled stations uses the wildcard BSSID (a value of all 1s) in the header of the frames they exchange, and may start sending and receiving data frames as soon as they arrive on the communication channel.
Because such stations are neither associated nor authenticated, the authentication and data confidentiality mechanisms provided by the IEEE 802.11 standard (and its amendments) cannot be used. These kinds of functionality must then be provided by higher network layers.
This amendment adds a new management frame for timing advertisement, which allows IEEE 802.11p enabled stations to synchronize themselves with a common time reference. The only time reference defined in the IEEE 802.11p amendment is UTC.
Enhanced receiver performances
Some optional enhanced channel rejection requirements (for both adjacent and nonadjacent channels) are specified in this amendment in order to improve the immunity of the communication system to out-of-channel interferences. They only apply to OFDM transmissions in the 5GHz band (IEEE 802.11a PHY layer).
Use of the 5.9GHz band
The IEEE 802.11p amendment allows the use of the 5.9GHz band (5.850-5.925 GHz) with 5MHz, 10MHz and 20MHz channel spacings, and specifies the requirements for using this band in the United States and in Europe.
The 802.11p Task Group was formed in November 2004. Lee Armstrong was chair and Wayne Fisher technical editor. Drafts were developed from 2005 through 2009. By April 2010 draft 11 had been approved by 99% affirmative votes and no comments. The approved amendment was published July 15, 2010. Its title was "Amendment 6: Wireless Access in Vehicular Environments".
In August 2008 the European Commission allocated part of the 5.9 GHz band for priority road safety applications and inter-vehicle, infrastructure communications. The intention is that compatibility with the USA will be ensured even if the allocation is not exactly the same; frequencies will be sufficiently close to enable the use of the same antenna and radio transmitter/receiver.
Simulations published in 2010 predict delays of at the most tens of milliseconds for high-priority traffic.
- "IEEE 1609 - Family of Standards for Wireless Access in Vehicular Environments (WAVE)". U.S. Department of Transportation. January 9, 2006. Retrieved 2007-07-15.
- "E2213-03 Standard Specification for Telecommunications and Information Exchange Between Roadside and Vehicle Systems". ASTM International. Retrieved 2007-07-15.
- "Final draft ETSI ES 202 663 V1.1.0 (2009-11)". European Telecommunications Standards Institute. Retrieved 2013-04-16.
- "Status of Project IEEE 802.11 Task Group p: Wireless Access in Vehicular Environments". IEEE. 2004–2010. Retrieved August 10, 2011.
- "Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications Amendment 6: Wireless Access in Vehicular Environments". IEEE 802.11p published standard. IEEE. July 15, 2010. Retrieved August 10, 2011.
- "Cars that talk: Commission earmarks single radio frequency for road safety and traffic management". European Commission. 2008-08-05. Retrieved 2008-08-23.
- Sebastian Grafling; Petri Mahonen; Janne Riihijarvi (June 2010). "Performance evaluation of IEEE 1609 WAVE and IEEE 802.11p for vehicular communications". Second International Conference on Ubiquitous and Future Networks (ICUFN): 344–348. doi:10.1109/ICUFN.2010.5547184.
- What is DSRC/WAVE? UCLA article about their testbed
- Intelligent Transportation gets 802.11p Daily Wireless July 15, 2004
- When Wi-Fi Will Drive Adam Stone Wi-Fi Planet
- UCLA on campus vehicular testbed
- Drive C2X European Integrated Project focussed on rolling out cooperative systems
- SCORE@F French FOT on Cooperative System/ Système COopératif Routier Expérimental Français
- SAFESPOT European Integrated Project on cooperative vehicular systems for road safety
- CVIS Cooperative Vehicle Infrastructure Systems
- PRESERVE European Project focused on Security and Privacy of V2X communications