Vehicular communication systems - AbsoluteAstronomy.com

Vehicular Communication Systems are an emerging type of network

Computer network

A computer network, often simply referred to as a network, is a collection of hardware components and computers interconnected by communication channels that allow sharing of resources and information....

s in which vehicle

Vehicle

A vehicle is a device that is designed or used to transport people or cargo. Most often vehicles are manufactured, such as bicycles, cars, motorcycles, trains, ships, boats, and aircraft....

s and roadside units are the communicating nodes; providing each other with information, such as safety warnings and traffic information. As a cooperative approach, vehicular communication systems can be more effective in avoiding accidents and traffic congestions than if each vehicle tries to solve these problems individually.

Generally vehicular networks are considered to contain two types of nodes; vehicles and roadside stations. Both are Dedicated Short Range Communications

Dedicated Short Range Communications

Dedicated short-range communications are one-way or two-way short- to medium-range wireless communication channels specifically designed for automotive use and a corresponding set of protocols and standards....

(DSRC) devices. DSRC works in 5.9 GHz band with bandwidth of 75 MHz and approximate range of 1000m. The network should support both private data communications and public (mainly safety) communications but higher priority is given to public communications.
Vehicular communications is usually developed as a part of Intelligent Transport Systems (ITS). ITS seeks to achieve safety and productivity through intelligent transportation which integrates communication between mobile and fixed nodes. To this end ITS heavily relies on wired and wireless communications.

Motivation

The main motivation for vehicular communication systems is safety and eliminating the excessive cost of traffic collisions. According to World Health Organizations (WHO), road accidents annually cause approximately 1.2 million deaths worldwide; one fourth of all deaths caused by injury. Also about 50 million persons are injured in traffic accidents. If preventive measures are not taken road death is likely to become the third-leading cause of death in 2020 from ninth place in 1990.

However the deaths caused by car crashes are in principle avoidable. US Department of Transport states that 21,000 of the annual 43,000 road accident deaths in the US are caused by roadway departures and intersection-related incidents. This number can be significantly lowered by deploying local warning systems through vehicular communications. Departing vehicles can inform other vehicles that they intend to depart the highway and arriving cars at intersection

Intersection (road)

An intersection is a road junction where two or more roads either meet or cross at grade . An intersection may be 3-way - a T junction or fork, 4-way - a crossroads, or 5-way or more...

s can send warning messages to other cars traversing that intersection. Studies show that in Western Europe a mere 5 km/h decrease in average vehicle speeds could result in 25% decrease in deaths. Policing speed limits will be notably easier and more efficient using communication technologies.

Although the main advantage of vehicular networks is safety improvements, there are several other benefits. Vehicular networks can help in avoiding congestion and finding better routes by processing real time data. This in return saves both time and fuel and has significant economic advantages.

Development

Vehicular communications is mainly motivated by the desire to implement Intelligent Transport Systems (ITS) because of their key benefits in safety and traveling ease. Several ITS institutions operate around the world to bring ITS concepts to real world. In the United States one of the main players is U.S. Department of Transportation (USDoT) . The federal DoT promotes ITS through investment in potentially high payoff initiatives. One of these major initiatives, Vehicle Infrastructure Integration (VII), seeks to increase safety by providing vehicle to vehicle and vehicle to roadside units communications through Dedicated Short Range Communications (DSRC).

Intelligent Transportation Society of America (ITSA), which has members from many diverse areas including private companies, universities, and governmental agencies, aims to improve cooperation among public and private sector organizations. ITSA summarizes its mission statement as “vision zero” meaning its goal is to reduce the fatal accidents and delays as much as possible.

Many universities are pursuing research and development of vehicular ad hoc networks. For example, University of California

University of California

The University of California is a public university system in the U.S. state of California. Under the California Master Plan for Higher Education, the University of California is a part of the state's three-tier public higher education system, which also includes the California State University...

, Berkeley

Berkeley, California

Berkeley is a city on the east shore of the San Francisco Bay in Northern California, United States. Its neighbors to the south are the cities of Oakland and Emeryville. To the north is the city of Albany and the unincorporated community of Kensington...

is participating in California Partners for Advanced Transit and Highways (PATH), along with several other universities in California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

and elsewhere such as Stanford, UCLA, MIT, Texas A&M

Texas A&M University

Texas A&M University is a coeducational public research university located in College Station, Texas . It is the flagship institution of the Texas A&M University System. The sixth-largest university in the United States, A&M's enrollment for Fall 2011 was over 50,000 for the first time in school...

etc.

Car manufacturers and communication corporations are also investing in vehicular communications; among them are Kapsch

Kapsch

The Kapsch Group, headquartered in Vienna, Austria, is an international Road Telematics, Information Technology and Telecommunications Company. The corporate group, with more than 4,000 employees worldwide generated total revenue of € 829.9 Million as of March 2011 and has invested € 55.8 Million ...

, General Motors

General Motors

General Motors Company , commonly known as GM, formerly incorporated as General Motors Corporation, is an American multinational automotive corporation headquartered in Detroit, Michigan and the world's second-largest automaker in 2010...

, Daimler Chrysler, Ford Motor Company

Ford Motor Company

Ford Motor Company is an American multinational automaker based in Dearborn, Michigan, a suburb of Detroit. The automaker was founded by Henry Ford and incorporated on June 16, 1903. In addition to the Ford and Lincoln brands, Ford also owns a small stake in Mazda in Japan and Aston Martin in the UK...

, Siemens

Siemens

Siemens may refer toSiemens, a German family name carried by generations of telecommunications industrialists, including:* Werner von Siemens , inventor, founder of Siemens AG...

, Honda

Honda

is a Japanese public multinational corporation primarily known as a manufacturer of automobiles and motorcycles.Honda has been the world's largest motorcycle manufacturer since 1959, as well as the world's largest manufacturer of internal combustion engines measured by volume, producing more than...

, Toyota, BMW

BMW

Bayerische Motoren Werke AG is a German automobile, motorcycle and engine manufacturing company founded in 1916. It also owns and produces the Mini marque, and is the parent company of Rolls-Royce Motor Cars. BMW produces motorcycles under BMW Motorrad and Husqvarna brands...

, Mercedes-Benz

Mercedes-Benz

Mercedes-Benz is a German manufacturer of automobiles, buses, coaches, and trucks. Mercedes-Benz is a division of its parent company, Daimler AG...

and Mark IV

Mark IV

Mark IV or Mark 4 often refers to the fourth version of a product, frequently military hardware. "Mark", meaning "model" or "variant", can be abbreviated "Mk."Mark IV or Mark 4 can specifically refer to:-In military and weaponry:...

.

Integrated automobile devices like OnStar

OnStar

OnStar Corporation is a subsidiary of General Motors that provides subscription-based communications, in-vehicle security, hands free calling, turn-by-turn navigation, and remote diagnostics systems throughout the United States, Canada and China. A similar service is known as ChevyStar in Latin...

have begun to make a presence on U.S. markets, with automobile manufacturers like GM offering them as options on their vehicles. Third party companies use these devices to offer services such as directions and emergency assistance to their customers. Although these devices may add an extra level of safety and peace of mind, they do not offer drivers the freedom to communicate with each other.

V2V

V2V (short for vehicle to vehicle) is an automobile technology designed to allow automobiles to "talk" to each other. The systems will use a region of the 5.9 GHz band set aside by the United States Congress in 1999, the unlicensed frequency also used by WiFi.

V2V is currently in active development by General Motors, which demonstrated the system in 2006 using Cadillac vehicles. Other automakers working on V2V include BMW, Daimler, Honda, Mercedes and Volvo.

Technical specifications

Two categories of draft standards provide outlines for vehicular networks. These standards constitute a category of IEEE standards for a special mode of operation of IEEE 802.11 for vehicular networks called Wireless Access in Vehicular Environments (WAVE).
802.11p is an extension to 802.11 Wireless LAN medium access layer (MAC) and physical layer

Physical layer

The physical layer or layer 1 is the first and lowest layer in the seven-layer OSI model of computer networking. The implementation of this layer is often termed PHY....

(PHY) specification. As of November 2006 Draft 1.3 of this standard is approved . 802.11p aims to provide specifications needed for MAC and PHY layers for specific needs of vehicular networks.
IEEE 1609 is a family of standards which deals with issues such as management and security of the network:

1609.1 -Resource Manager: This standard provides a resource manager for WAVE, allowing communication between remote applications and vehicles.
1609.2 -Security Services for Applications and Management Messages
1609.3 -Networking Services: This standard addresses network layer issues in WAVE.
1609.4 -Multi-channel Operation: This standard deals with communications through multiple channels.

The current state of these standards is trial-use.
A vehicular communication networks which complies with the above standards supports both vehicular on-board units (OBU) and roadside units (RSU). RSU acts similar to a wireless LAN access point and can provide communications with infrastructure. Also, if required, RSU must be able to allocate channels to OBUs. There is a third type of communicating nodes called Public Safety OBU (PSOBU) which is a vehicle with capabilities of providing services normally offered by RSU. These units are mainly utilized in police cars, fire trucks, and ambulances in emergency situations.

As mentioned before DSRC provides several channels (seven 10 MHz channels in North America) for communications. Standards divide the channels into two categories: a control channel and service channels. Control channel is reserved for broadcasting and coordinating communications which generally takes place in other channels. Although DSRC devices are allowed to switch to a service channel, they must continuously monitor the control channel. There is no scanning and association as there is in normal 802.11. All such operations are done via a beacon sent by RSUs in the control channel. While OBUs and RSUs are allowed to broadcast messages in the control channels, only RSUs can send beacon messages.

In North America DSRC devices operate over seven 10 MHz channels. Two of the channels are used solely for public safety applications which means that they can only be used for communications of message with a certain priority or higher.

Although 802.11p and 1609 drafts specify baselines for developing vehicular networks, many issues are not addressed yet and more research is required.

Applications

Vehicular communication networks will provide a wide range of applications with different characteristics. As these networks have not yet been implemented, a list of such applications is speculative and apt to change in the future (However safety, which is the main purpose of these networks, will most probably remain the most important applications). Furthermore some of these applications require technologies that are not available now. Ultimately we would like to delegate the full handling control of our cars to the vehicles themselves; somewhat similar to autopilot. The classifications of applications is not unique and many institutions involved in intelligent transportation systems propose their own set of applications and classifications. We classify the possible applications in the following categories:

Safety

Providing safety is the primary objective of vehicular communication networks. Vehicles who discover an imminent danger such as an obstacle inform others. Electronic sensors in each car can detect abrupt changes in path or speed and send an appropriate message to neighbors. Vehicles can notify close vehicles of the direction they are taking so the drivers can make better decisions; a more advanced version of turn signals. In more advanced systems, at intersections the system can decide which vehicle has the right to pass first and alert all the drivers. Some of the immediate applications are:

Warnings on entering intersections.
Warnings on departing the highway
Highway
A highway is any public road. In American English, the term is common and almost always designates major roads. In British English, the term designates any road open to the public. Any interconnected set of highways can be variously referred to as a "highway system", a "highway network", or a...

s
Obstacle discovery
Sudden halts warnings
Reporting accidents
Lane change warnings

Traffic management

Traffic management is utilized by authorities to ease traffic

Traffic

Traffic on roads may consist of pedestrians, ridden or herded animals, vehicles, streetcars and other conveyances, either singly or together, while using the public way for purposes of travel...

flow and provide a real time response to congestions. Authorities may change traffic rules according to a specific situation such as hot pursuits and bad weather. Applications include:

Variable speed limits
Adaptable traffic lights
Automated traffic intersection control
Accommodating ambulances, fire trucks, and police cars

Driver assistance systems

Roadside units can provide drivers with information which help them in controlling the vehicle. Even in the absence of RSUs, small transmitters may be able to issue warnings such as bridge or tunnel height or gate width:

Parking a vehicle
Cruise control
Cruise control
Cruise control is a system that automatically controls the speed of a motor vehicle. The system takes over the throttle of the car to maintain a steady speed as set by the driver.-History:...
Lane keeping assistance
Roadsign recognition

Policing and enforcement

Police can use vehicular communications in several ways:

Surveillance
Surveillance
Surveillance is the monitoring of the behavior, activities, or other changing information, usually of people. It is sometimes done in a surreptitious manner...
Speed limit warnings
Restricted entries
Pull-over commands

Pricing and payments

Electronic payment results in convenient payments and avoiding congestions caused by toll collection and makes pricing more manageable. For instance tolls can be variable for weekdays and weekends and during rush hours:

Toll
Toll road
A toll road is a privately or publicly built road for which a driver pays a toll for use. Structures for which tolls are charged include toll bridges and toll tunnels. Non-toll roads are financed using other sources of revenue, most typically fuel tax or general tax funds...

collecting
Parking
Parking
Parking is the act of stopping a vehicle and leaving it unoccupied for more than a brief time. Parking on one or both sides of a road is commonly permitted, though often with restrictions...

payments

Direction and route optimization

For reaching a destination there are usually many different routes. By collecting relevant information system can find the best paths in terms of travel time, expenses (such as toll and fuel), …

Travel-related information

In an unfamiliar town drivers may be assisted to find relevant information about available services:

Maps
Business locations
Car services
Gas stations

General information services

As with many other communication networks, vehicular networks can be used to obtain various content and services (not directly related to traveling). In this respect there are numerous applications. In the case that wireless vehicular networks are integrated to the Internet, which is very likely, virtually every application that is currently used in the Internet will find its way to vehicular networks as well. However applications with lower bandwidth requirements are likely to become widespread sooner. Some applications can be:

Web surfing
File downloads
Email
Email
Electronic mail, commonly known as email or e-mail, is a method of exchanging digital messages from an author to one or more recipients. Modern email operates across the Internet or other computer networks. Some early email systems required that the author and the recipient both be online at the...
Gaming

Automated highways

Automated highway is not yet realizable but nevertheless is an important application. In these highways the vehicles are able to cruise without help of their drivers. This is done by cooperation between vehicles. For example each vehicle knows the speed and direction of travel of its neighboring vehicles through communication with them. The status is updated frequently; therefore each vehicle can predict the future up to some necessary time and is able to make appropriate decisions in appropriate time. Because automated highways are not limited by human response time, much higher speeds will be possible . This application is virtually impossible without utilizing vehicular networks.

External links

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.