轉自： http://en.wikipedia.org/wiki/Vehicular_ad-hoc_network
A Vehicular Ad-Hoc Network, or VANET is a technology that uses moving cars as nodes in a network to create a mobile network. VANET turns every participating car into a wireless router or node, allowing cars approximately 100 to 300 metres of each other to connect and, in turn, create a network with a wide range. As cars fall out of the signal range and drop out of the network, other cars can join in, connecting vehicles to one another so that a mobile Internet is created. It is estimated that the first systems that will integrate this technology are police and fire vehicles to communicate with each other for safety purposes.
Applications
Most of the concerns of interest to MANets are of interest in VANets, but the details differ. Rather than moving at random, vehicles tend to move in an organized fashion. The interactions with roadside equipment can likewise be characterized fairly accurately. And finally, most vehicles are restricted in their range of motion, for example by being constrained to follow a paved highway.In addition, in the year 2006 the term MANet mostly describes an academic area of research, and the term VANet perhaps its most promising area of application.
VANET offers countless benefits to organizations of any size. Automobile high speed Internet access would transform the vehicle’s on-board computer from a nifty gadget to an essential productivity tool, making virtually any web technology available in the car. While such a network does pose certain safety concerns (for example, one cannot safely type an email while driving), this does not limit VANET’s potential as a productivity tool. It allows for “dead time”—time that is being wasted while waiting for something—to be transformed into “live time”—time that is being used to accomplish tasks. A commuter can turn a traffic jam into a productive work time by having his email downloaded and read to him by the on-board computer, or if traffic slows to a halt, read it himself. While waiting in the car to pick up a friend or relative, one can surf the Internet. Even GPS systems can benefit, as they can be integrated with traffic reports to provide the fastest route to work. Lastly, it would allow for free, VoIP services such as GoogleTalk or Skype between employees, lowering telecommunications costs.
Technology
InVANET, or Intelligent Vehicular Ad-Hoc Networking, defines an Intelligent way of using Vehicular Networking. InVANET integrates on multiple ad-hoc networking technologies such as WiFi IEEE 802.11p, WAVE IEEE 1609, WiMAX IEEE 802.16, Bluetooth, IRA, ZigBee for easy, accurate, effective and simple communication between vehicles on dynamic mobility. Effective measures such as media communication between vehicles can be enabled as well methods to track the automotive vehicles is also preferred.InVANET helps in defining safety measures in vehicles, streaming communication between vehicles, infotainment and telematics.
Vehicular Ad-hoc Networks are expected to implement a variety of wireless technologies such as Dedicated Short Range Communications (DSRC) which is a type of WiFi. Other candidate wireless technologies are Cellular, Satellite, and WiMAX. Vehicular Ad-hoc Networks can be viewed as component of the Intelligent Transportation Systems (ITS).
Vehicular Networks are an envision of the Intelligent Transportation Systems (ITS). Vehicles communicate with each other via Inter-Vehicle Communication (IVC) as well as with roadside base stations via Roadside-to-Vehicle Communication (RVC). The optimal goal is that vehicular networks will contribute to safer and more efficient roads in the future by providing timely information to drivers and concerned authorities.