  The critical nature of vehicular communications requires their extensive
testing and evaluation. Analytical models can represent an attractive and
cost-effective approach for such evaluation if they can adequately model all
underlying effects that impact the performance of vehicular communications.
Several analytical models have been proposed to date to model vehicular
communications based on the IEEE 802.11p (or DSRC) standard. However, existing
models normally model in detail the MAC (Medium Access Control), and generally
simplify the propagation and interference effects. This reduces their value as
an alternative to evaluate the performance of vehicular communications. This
paper addresses this gap, and presents the first analytical models capable to
accurately model the performance of vehicle-to-vehicle communications based on
the IEEE 802.11p standard. The model quantifies the PDR (Packet Delivery Ratio)
as a function of the distance between transmitter and receiver. The paper also
presents new analytical models to quantify the probability of the four
different types of packet errors in IEEE 802.11p. In addition, the paper
presents the first analytical model capable to accurately estimate the Channel
Busy Ratio (CBR) metric even under high channel load levels. All the analytical
models are validated by means of simulation for a wide range of parameters,
including traffic densities, packet transmission frequencies, transmission
power levels, data rates and packet sizes. An implementation of the models is
provided openly to facilitate their use by the community.
