Vehicular Ad hoc Networks (VANETs)
The recent adoption of the various 802.11 wireless standards has caused a dramatic increase in the number of wireless data networks. Today, wireless LANs are highly deployed and the cost for wireless equipment is continuing to drop in price. Currently, an 802.11 adapter or access point (AP) can be purchased for next to nothing. As a result of the high acceptance of the 802.11 standards, academia and the commercial sector are looking for other applicable solutions for these wireless technologies. Mobile ad hoc networks (MANET) are one area that has recently received considerable attention. One promising application of mobile ad hoc networks is the development of vehicular ad hoc networks (VANET).
A MANET is a self forming network, which can function without the need of any centralized control. Each node in an ad hoc network acts as both a data terminal and a router. The nodes in the network then use the wireless medium to communicate with other nodes in their radio range. A VANET is effectively a subset of MANETs. The benefit of using ad hoc networks is it is possible to deploy these networks in areas where it isn't feasible to install the needed infrastructure. It would be expensive and unrealistic to install 802.11 access points to cover all of the roads in the United States. Another benefit of ad hoc networks is they can be quickly deployed with no administrator involvement. The administration of a large scale vehicular network would be a difficult task. These reasons contribute to the ad hoc networks being applied to vehicular environments.
Traffic fatalities are one of the leading causes of death in the United States. The Federal Communications Commission (FCC), realizing the problem of traffic fatalities in the US dedicated 75 MHz of the frequency spectrum in the range 5.850 to 5.925 GHz to be used for vehicletovehicle and vehicletoroadside communication. The 5.9 GHz spectrum was termed Dedicated Short Range Communication (DSRC) and is based on a variant of 802.11a. Seven channels of 10 MHz each make up DSRC, with six of the channels being used for services and one channel for control. The goal of the project is to enable the driver of a vehicle to receive information about their surrounding environment. The control channel is used to broadcast safety messages e.g. to alert the driver of potentially hazardous road conditions. The control channel is also used to announce the services that are available. If vehicle finds a service of interest on the control channel, it then switches to one of the service channels to use the service. A number of additional value added features are to be provided by the service channels such as the announcement of places of interest in the driver’s locations e.g. restaurants in the area or gas prices.
The creation of Vehicular Ad Hoc Networks (VANET) has also spawn much interest in the rest of the world, in German there is the FleetNet project and in Japan the ITS project. Vehicular ad hoc networks are also known under a number of different terms such as intervehicle communication (IVC), Dedicated Short Range Communication (DSRC) or WAVE. The goal of most of these projects is to create new network algorithms or modify the existing for use in a vehicular environment. In the future vehicular ad hoc networks will assists the drivers of vehicles and help to create safer roads by reducing the number of automobile accidents and it will help to convert the idea of auto pilot cars into reality.
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