Vehicular Ad Hoc networks: Communications on the road [Message from the Editor-in-Chief]

In front of you lies another issue on recent work in wireless technologies. Have you ever been trapped on a highly congested highway and unable to find a way to get out? Have you ever wished you had known the situation earlier in order to take a different route? Vehicular ad hoc networks (VANETs) could provide such services on the road, including traffic safety, driver convenience, and roadway efficiency, and could facilitate many types of in-vehicle services. For example, by using car-to-car communications, information on hazardous road conditions can be gathered quickly and disseminated immediately to avoid severe traffic accidents, location services can be provided to drivers if they so desire, and various kinds of infotainment and on-the-road social networking can be made possible. Unfortunately, to design an efficient VANET is very challenging. Channels between cars or between a car and the roadside communications facility are highly time varying due to high mobility, and hence should be carefully studied. The medium is shared among cars in communications; hence, its usage should be well coordinated for efficiency. Two VANET users may not be reachable directly, so how to enable their information exchange via potentially multihop communications should be addressed. For certain applications, information has to be reliably and securely delivered, so addressing reliable and/or secure communications over this highly unreliable wireless network is very important. Finally, one of the most important design issues is to find the killer applications over VANETs, which is a common theme for most wireless technologies. We cannot design an efficient network without knowing the services provided. Although there are intensive research activities in VANETs, we still lack convincingly important applications to motivate the full fledged development of VANETs.