An efficient group-based safety message transmission protocol for VANET

Vehicular Ad-hoc Network (VANET) is a type of mobile communication in which topology changes dynamically due to high mobility of vehicles. Vehicles use two types of messages to update their status and to communicate with other vehicles. First is Periodic Safety Message (PSM) which gives us information about position, speed etc. and second is Event Driven Safety Message (ESM) which occurs when emergency situation like hard breaking, sudden lane change, etc. When vehicle movement is abnormal either due to change in speed or direction, vehicles generate event-driven safety alert messages. Safety alert messages are needed to be very fast and reliable for VANET applications. In this paper, we propose a novel approach to improve safety alert message communication in VANET using grouping of vehicles. Firstly, vehicles form a group and select their Group Leader to communicate with other Group Leaders. Secondly, we send the safety alert message by using priority in the messages and context-based communication. The priority is set according to various types of accidents and by using context-based communication the ESM messages are send to those groups which are endangered by the accidents. Simulation of proposed scheme is performed on multi-lane roads by considering vehicles movement in a single direction. Performance is evaluated in terms of packet delivery ratio and back-off counter for multi-hop broadcast communication.