Communication requirements for crash avoidance

Safety applications are a driving force behind VANET deployment. Automobile manufacturers, government organizations, and consortia of the two have been investigating using VANETs for safety applications. Though VANETs are in large part designed for safety applications, researchers do not yet know the communication requirements of VANET safety messages. As a result, protocol designers have relied on generic network success metrics, such as packet delivery ratio, to evaluate their protocols. However, a more useful metric is the ability of currently proposed VANET schemes (e.g., for authentication, power control, etc.) to allow vehicles to receive safety messages and warn their drivers sufficiently in advance of an accident so that the driver can avoid the accident. Besides the basic safety message service, researchers have proposed other VANET mechanisms and services including mix zones [2,