  This paper proposes a novel three-dimensional (3D) theoretical regular-shaped
geometry-based stochastic model (RS-GBSM) and the corresponding
sum-of-sinusoids (SoS) simulation model for non-isotropic multiple-input
multiple-output (MIMO) vehicle-to-vehicle (V2V) Ricean fading channels. The
proposed RS-GBSM, combining line-of-sight (LoS) components, a two-sphere model,
and an elliptic-cylinder model, has the ability to study the impact of the
vehicular traffic density (VTD) on channel statistics, and jointly considers
the azimuth and elevation angles by using the von Mises Fisher distribution.
Moreover, a novel parameter computation method is proposed for jointly
calculating the azimuth and elevation angles in the SoS channel simulator.
Based on the proposed 3D theoretical RS-GBSM and its SoS simulation model,
statistical properties are derived and thoroughly investigated. The impact of
the elevation angle in the 3D model on key statistical properties is
investigated by comparing with those of the corresponding two-dimensional (2D)
model. It is demonstrated that the 3D model is more accurate to characterize
real V2V channels, in particular for pico cell scenarios. Finally, close
agreement is achieved between the theoretical model, SoS simulation model, and
simulation results, demonstrating the utility of the proposed models.
