An effective alert-message routing protocol for urban VANETs

Vehicular Ad-hoc Networks (VANETs) have become a very popular issue in recent years. VANETs are one kind of Mobile Ad-hoc Networks (MANETs), but it possesses different properties, such as faster node´s mobility and quick topological change. Therefore, the methods employed on MANETs would not be suitable for VANETs. VANETs have many kinds of applications such as increasing driving safety, decreasing traffic congestion and offering better driving services. One of the most important issues is how to disseminate “alert message” efficiently such that, when an accident happens, it could be warning drivers off to increase driving safety. The traditional method, flooding, provides a good reachability but it may causes “Broadcast Strom Problem”, resulting in bandwidth abuse. In this paper, we propose the bidirectional broadcasting scheme (BBS) which ensures bidirectional broadcasting on any kinds of roads, such that it could be suitable for both street and highway scenarios. The simulations are conducted with network simulator NS2. The simulation results show that the proposed scheme can achieve high reachability and low bandwidth usage.