  In this paper, we present a three-dimensional (3D) non-wide-sense stationary
(non-WSS) wideband geometry-based channel model for vehicle-to-vehicle (V2V)
communication environments. We introduce a two-cylinder model to describe
moving vehicles as well as multiple confocal semi-ellipsoid models to depict
stationary roadside scenarios. The received signal is constructed as a sum of
the line-of-sight (LoS), single-, and double-bounced rays with different
energies. Accordingly, the proposed channel model is sufficient for depicting a
wide variety of V2V environments, such as macro-, micro-, and picocells. The
relative movement between the mobile transmitter (MT) and mobile receiver (MR)
results in time-variant geometric statistics that make our channel model
non-stationary. Using this channel model, the proposed channel statistics,
i.e., the time-variant space correlation functions (CFs), frequency CFs, and
corresponding Doppler power spectral density (PSD), were studied for different
relative moving time instants. The numerical results demonstrate that the
proposed 3D non-WSS wideband channel model is practical for characterizing real
V2V channels.
