  To date, VANET research efforts have relied heavily on simulations, due to
prohibitive costs of deploying real world testbeds. Existing channel models
implemented in discrete-event VANET simulators are by and large simple
stochastic radio models, based on the statistical properties of the chosen
environment. It was shown that such models are unable to provide satisfactory
accuracy for typical VANET scenarios.
  We performed extensive measurements in different environments (open space,
highway, suburban, urban, parking lot) to characterize in detail the impact
that vehicles have on communication in terms of received power, packet delivery
rate, and effective communication range. Since the impact of vehicles was found
to be significant, we developed a model that accounts for vehicles as
three-dimensional obstacles and takes into account their impact on the line of
sight obstruction, received signal power, packet reception rate, and message
reachability. The model is based on the empirically derived vehicle dimensions,
accurate vehicle positioning, and realistic mobility patterns. We validate the
model against extensive measurements. To enable realistic modeling in urban and
suburban environments, we developed a model that incorporates static objects as
well. The model requires minimum geographic information: the location and the
dimensions of modeled objects (vehicles, buildings, and foliage). We validate
the model against measurements and show that it successfully captures both
small-scale and large-scale propagation effects in different environments
(highway, urban, suburban, open space).
