  Platooning is a critical technology to realize autonomous driving. Each
vehicle in platoons adopts the IEEE 802.11p standard to exchange information
through communications to maintain the string stability of platoons. However,
one vehicle in platoons inevitably suffers from a disturbance resulting from
the leader vehicle acceleration/deceleration, wind gust and uncertainties in a
platoon control system, i.e., aerodynamics drag and rolling resistance moment
etc. Disturbances acting on one vehicle may inevitably affect the following
vehicles and cause that the spacing error is propagated or even amplified
downstream along the platoon, i.e., platoon string instability. In this case,
the connectivity among vehicles is dynamic, resulting in the performance of
802.11p in terms of packet delay and packet delivery ratio being time-varying.
The effect of the string instability would be further deteriorated once the
time-varying performance of 802.11p cannot satisfy the basic communication
requirement. Unlike the existing works which only analyze the steady
performance of 802.11p in vehicular networks, we will focus on the impact of
disturbance and construct models to analyze the time-dependent performance of
802.11p-based platooning communications. The effectiveness of the models is
validated through simulation results. Moreover, the time-dependent performance
of 802.11p is analyzed through numerical results and it is validated that
802.11p is able to satisfy the communication requirement under disturbance.
