Vehicle-to-Vehicle and Vehicle-to-Infrastructure Communication Protocols
Today, it can be seen that cars and their subsystems are constantly developing, and the biggest progress is in “Advanced Driver Support Systems”. Still, researchers spend a lot of time seeing and developing the future of advanced road transport systems, which consist of many vehicles and where drivers communicate with road systems.
The vision that will change the driving experience and transportation from start to finish has two key elements:
• Vehicle-to-Infrastructure Communication (V2I)
• Vehicle-to-Vehicle Communication (V2V)
The V2I and V2X concepts include revolutionary developments for transport – efficient fuel use, less road construction work, road safety for pedestrians and cyclists as well as drivers. Control is seen as the keyword for both concepts.
Vehicle-to-Infrastructure Communication (V2I)
In V2I, infrastructure plays a coordinating role, working together globally or locally. The system provides information on traffic and road conditions by examining the behavior of vehicle groups. An example is the ramp metering process (traffic density measurements on ramps and traffic density measurements on a road), which requires limited sensors and actuators, as used previously.
In a more advanced scenario, vehicle speed changes will be offered by the infrastructure in order to optimize fuel consumption and traffic travel speeds. This suggestion can be transmitted via digital traffic signs on the road or directly to the vehicle via wireless network. Looking further, in some cases vehicle control can be maintained semi-automatically. (Taking into account the restrictions on automatic driving, limited by the Vienna Convention on Road Traffic, discussed later.) Some experts predict that by 2020 V2I systems will be ready for use on the continent of Europe.
The figure on the left shows two different traffic situations. In the left panel, the traffic density is low and the central infrastructure controller tries to smooth the accelerations and decelerations of the individual vehicles in order to increase fuel efficiency; In the right panel, due to more congestion, infrastructure control primarily deals with queues at intersections and again tries to reduce fuel consumption.
Vehicle-to-Vehicle Communication (V2V)
Vehicle-to-vehicle communication (V2V) aims to organize the interaction between vehicles and improve cooperation between them. V2V is more difficult to implement due to its decentralized nature.
Initiating such information exchange requires a collaborative effort between vehicle manufacturers and suppliers in terms of communication technology, protocols and the like; Efforts in this direction continue (CAR2CAR Consortium). The communication technology is based on IEEE 802.11, also known as Wireless LAN. A frequency spectrum in the 5.9-GHz range is available for use in Europe, with a similar allocation in the USA. (Although the systems are not yet compatible).
In the V2V concept, when two vehicles come within communication range of each other or of a roadside station, they automatically establish a connection. Allows sharing of ad-hoc network locations, speeds, and directions. Each vehicle can also act as a distributor and transmit messages received from other vehicles to road stations or other drivers. The routing algorithm handles the position of vehicles and rapid changes of the network topology. The system should take into account uncertainties, delays, partial measurements, safety and performance targets, and other considerations, and make automated or semi-automatic decisions; be able to give warning/information and potentially influence actions.
Vienna Road Convention
This international agreement, designed to facilitate international road traffic and improve road safety, was adopted at the United Nations Economic and Social Council Road Traffic Conference in 1968 and entered into force on 21 May 1977 (http://www.unece.org/trans/conventn/ crt1968e.pdf).
“Every driver should always be able to control his own vehicle.”
This agreement conflicts with the concept of automatic driving control to some extent. However, it does not assume full control of the vehicle and helps the driver to follow a desired path in cases where he/she loses control of the vehicle; anti-lock braking or electronic stabilization systems are acceptable. However, it seems necessary to make changes in congress decisions as a result of technological advances.
• The Impact of Control Technology, T. Samad and A.M. Annaswamy