  This paper describes an implementation of spatial consistency in the NYUSIM
channel simulation platform. NYUSIM is a millimeter wave (mmWave) channel
simulator that realizes measurement-based channel models based on a wide range
of multipath channel parameters, including realistic multipath time delays and
multipath components that arrive at different 3-D angles in space, and
generates life-like samples of channel impulse responses (CIRs) that
statistically match those measured in the real world. To properly simulate
channel impairments and variations for adaptive antenna algorithms or channel
state feedback, channel models should implement spatial consistency which
ensures correlated channel responses over short time and distance epochs. The
ability to incorporate spatial consistency into channel simulators will be
essential to explore the ability to train and deploy massive multiple-input and
multiple-output (MIMO) and multi-user beamforming in next-generation mobile
communication systems. This paper reviews existing modeling approaches to
spatial consistency, and describes an implementation of spatial consistency in
NYUSIM for when a user is moving in a square area having a side length of 15 m.
The spatial consistency extension will enable NYUSIM to generate realistic
evolutions of temporal and spatial characteristics of the wideband CIRs for
mobile users in motion, or for multiple users who are relatively close to one
another.
