Recovering VANET Safety Message in Transmission Holes
The core concern in vehicular ad hoc networks (VANETs) is the reliable transfer of safety-related messages to all endangered vehicles on the road. The recent discovery of the presence of transmission holes in the VANET communication range poses a serious challenge in the safety-message propagation. In this work, a technique for recovering the safety message for vehicles located in the transmission holes is proposed. Each vehicle that successfully receives the safety message actively estimates propagation loss for its immediate neighbors. If the receiving vehicle determines one of its neighbors being located in a coverage hole, the safety message is rebroadcast by the receiving vehicle. The propagation-loss estimation makes use of the topology information appended in the periodic beaconing messages. The proposed technique is evaluated in the ns-3 simulator. The simulation results suggest that the proposed technique improves the overall message-dissemination reliability over the existing techniques.