Design and evaluation of Hi-CAST and its variants for safety message dissemination in VANET

Vehicular ad hoc networks (VANET) enable promising new possibilities to enhance traffic safety and efficiency. The vision of VANET is that vehicles communicate spontaneously, exchanging traffic-related information such as road conditions and hazardous situations. Traffic-related information can be disseminated via multi-hop routing, thus enabling the propagation of important information over longer distances. The major contribution of this paper is to propose Hi-CAST, a hybrid intelligent broadcast algorithm for alert message dissemination in VANET. We also propose various variants of Hi-CAST considering fading factors. To deliver alert messages effectively, Hi-CAST uses delay and probabilistic broadcast protocols in conjunction with token protocols. The performance of Hi-CAST is evaluated through simulation and compared with that of other alert message dissemination algorithms. From the simulation results, we know that our Hi-CAST is superior to Simple, p-Persistence and EDB algorithms. Also, we design Hi-CAST (best) hybrid algorithm which combines Hi-CAST (parabolic) and Hi-CAST (cubic).