A simulation study: Is the broadcast storming really harmful for emergency delivery in VANETs?

The broadcasting service of safety message has been introduced in vehicular ad-hoc networks (VANETs) as the service for safety application. The broadcast communication is considered as the most appropriate technique for distributing the safety message in VANETs because of the least of time needed by the medium access process and the proximity of the destination nodes. However, the broadcast service may have some disadvantages regarding to broadcast storm problem in dense area. In car collision condition, the emergency message from the collided cars should be propagated as fast as possible so the upcoming cars could avoid the pileup of cars accident by receiving the alert message from the front cars. In this paper, we discuss the behavior of conventional broadcast mechanism which blindly broadcast the emergency message to the neighboring nodes. We compare the conventional broadcast mechanism with one of intelligent broadcast mechanism called distance-based broadcast mechanism. From the simulation results, we observed that the penetration rate of the conventional broadcast mechanism gives a good result with only 20ms average propagation delay from the source to the last destination in 4.7Km road length which means the emergency message is well penetrated.