  Vehicular Ad hoc Networks (VANETs) aim to improve transportation activities
that include traffic safety, transport efficiency and even infotainment on the
wheels, in which a great number of traffic event-driven messages are needed to
disseminate in a region of interest timely. However, due to the nature of
VANETs, highly dynamic mobility and frequent disconnection, data dissemination
faces great challenges. Inter-Vehicle Communication (IVC) protocols are the key
technology to mitigate this issue. Therefore, we propose an infrastructure-less
Traffic Adaptive data Dissemination (TrAD) protocol that considers road traffic
and network traffic status for both highway and urban scenarios. TrAD is
flexible to fit the irregular road topology and owns double broadcast
suppression techniques. Three state-of-the-art IVC protocols have been compared
with TrAD by means of realistic simulations. The performance of all protocols
is quantitatively evaluated with different real city maps and traffic routes.
Finally, TrAD gets an outstanding overall performance in terms of several
metrics, even though under the worse condition of GPS drift.
