Vehicular ad hoc networks (VANETs)are created by applying the principles of mobile ad hoc networks (MANETs) – thespontaneous creation of a wireless network for data exchange – to the domain ofvehicles. VANETs were first mentioned and introduced in 2001 under”car-to-car ad hoc mobile communication and networking” applications,where networks can be formed and information can be relayed among cars. It wasshown that vehicle-to-vehicle and vehicle-to-roadside communicationsarchitectures will co-exist in VANETs to provide road safety, navigation andother roadside services. VANETs are a key part of the intelligenttransportation systems (ITS) framework. VANETs are referred as IntelligentTransportation Networks. VANET became mostly synonymous with the more genericterm Inter-Vehicle Communication(IVC) although the focus remainson the aspect of spontaneous networking, much less on the use of infrastructurelike Road Side Units (RSUs) or cellular networks. VANETs can use any wirelessnetworking technology as their basis.
The most prominent are short range radiotechnologies like WLAN (either standard Wi-Fi or ZigBee. In addition, cellulartechnologies or LTE can be used for VANETs. The latest technology for thiswireless networking is visible light communication.VANETssupport a wide range of applications – from simple one hop informationdissemination of, e.
g., cooperative awareness messages (CAMs) to multi-hopdissemination of messages over vast distances. Most of the concerns of interestto mobile ad hoc networks (MANETs) are of interest in VANETs, but the detailsdiffer. Rather than moving at random, vehicles tend to move in an organizedfashion. The interactions with roadside equipment can likewise be characterizedfairly accurately. And finally, most vehicles are restricted in their range ofmotion, for example by being constrained to follow a paved highway. The variousapplications of VANETS are listed below.Safety applications include monitoringof the surrounding road, approaching vehicles, surface of the road, road curvesetc.
The Road safety applications can be classified as: ü Real-time traffic: The real time traffic data can bestored at the RSU and can be available to the vehicles whenever and whereverneeded. This can play an important role in solving the problems such as trafficjams, avoid congestions and in emergency alerts such as accidents etc. ü Co-operative Message Transfer: Slow/StoppedVehicle will exchange messages and co-operate to help other vehicles. Thoughreliability and latency would be of major concern, it may automate things likeemergency braking to avoid potential accidents. Similarly, emergency electronicbrake-light may be another application. ü Post Crash Notification: A vehicleinvolved in an accident would broadcast warning messages about its position totrailing vehicles so that it can take decision with time in hand as well as tothe highway patrol for tow away support. ü Road Hazard Control Notification: Cars notifyingother cars about road having landslide or information regarding road featurenotification due to road curve, sudden downhill etc.
ü Cooperative Collision Warning: Alerts twodrivers potentially under crash route so that they can mend their ways.Commercialapplications will provide the driver with the entertainment and services as webaccess, streaming audio and video. The Commercial applications can beclassified as: ü Remote Vehicle Personalization/ Diagnostics: It helps indownloading of personalized vehicle settings or uploading of vehiclediagnostics from/to infrastructure.
ü Internet Access: Vehicles can access internetthrough RSU if RSU is working as a router. ü Digital map downloading: Map ofregions can be downloaded by the drivers as per the requirement beforetraveling to a new area for travel guidance. Also, Content Map DatabaseDownload acts as a portal for getting valuable information from mobile hotspots or home stations. ü Real Time Video Relay: On-demandmovie experience will not be confined to the constraints of the home and thedriver can ask for real time video relay of his favorite movies.
ü Value-added advertisement: This isespecially for the service providers, who want to attract customers to theirstores. Announcements like petrol pumps, highways restaurants to announce theirservices to the drivers within communication range. This application can beavailable even in the absence of the Internet.