Vehicular Ad Hoc Networks: Current Issues and Future Challenges ◾ 369
sacrifice data packets and beacon messages to the benefit of time critical messages. Besides, scal-
ability of these techniques is questionable when the number of time critical messages increases
in the network. Distance-based broadcast mechanism works well when traffic density is rela-
tively low. In high-traffic-density conditions, there will be many nodes with identical or nearly
equal forwarding probability or equally assigned time slot since these parameters are calculated
according to the distance of vehicles to the message transmitter. Furthermore, in the slotted
p-persistence broadcast mechanism, the choice of the parameter p, which plays a key role in the
ultimate pe