Find in Library

Abstract In VANET (vehicular ad hoc network), a negative message has an objective vehicle and describes the negative attributes of the vehicle. Broadcasting negative messages in VANET is essential to make the VANET secure for these messages are about the untrustworthy vehicles. The epidemic model distributes negative messages rapidly with unlimited broadcasting, but uncontrolled epidemic may cause flooding storm. TTL (time-to-live) can be used to control broadcasting, but it may heavily decrease the coverage of negative messages in VANET. Meet-Table is used with TTL to solve the problem. A Meet-Table is a data structure held by a vehicle to record vehicles it met. When a vehicle receives a message, it checks whether the message’s objective vehicle is in its Meet-Table. If it is, the vehicle resets the TTL of the message to the maximum TTL to extend the transmission of the message. The negative message, coverage percentage and accurate coverage percentage of the negative message, and the Meet-Table are formally defined. The algorithm for broadcasting negative messages with Meet-Table and TTL is given. The simulation results show that Meet-Table can increase the coverage and decrease the delay of negative messages. More importantly, the simulation results show that the coverage increased by Meet-Table is accurate.