Abstract
Vehicular Ad Hoc Networks (VANETs) are becoming the favorable option for the Intelligent Transportation Systems (ITS). The efficient distribution of information in the form of data packets, is essential in order to support the vision of smart ITS. In VANETs, vehicles communicate with other vehicles directly or through existing infrastructure for sharing traffic information. Th data distribution is usually done using broadcast method. Data broadcast in VANETs is a challenging issue since high mobility vehicles with varying density have to share and route the safety critical information to other intended vehicles in real time. Thus, it needs to be addressed by the existing and new solutions for the same. Keeping this in mind, this study presents a detailed description of the existing data broadcast protocol for VANETs with an objective of selecting a particular scheme for a particular application with respect to its benefits over the others. This study reviews and compares numerous existing multi-hop data broadcast protocols in terms of various attributes such as data forwarding strategies, objectives, type of architecture, application scenarios, assumptions, evaluation metrics, simulation platform. Furthermore, an original taxonomy of these protocols is introduced based upon the road scenarios with critical discussion on each categorization with respect to its strengths, weaknesses and important constraints. Finally, various perspectives, challenges and shortcomings of the existing research work are discussed.