  The next generation of wireless networks will feature a more flexible radio
access design, integrating multiple new technological solutions (e.g., massive
Multiple-Input Multiple-Output (MIMO), millimeter waves) to satisfy different
verticals and use cases. The performance evaluation of these networks will
require more complex models to represent the interactions of different
components of the networks accurately. For example, channel models, which are
of paramount importance to precisely characterize the behavior of such systems,
need to account for multi-antenna systems and new frequency bands. This paper
presents the ns-3 implementation of a spatial channel model for the 0.5-100 GHz
spectrum, following the 3GPP Technical Report 38.901. The code, designed to be
flexible and easily extensible, is integrated in ns-3's antenna, propagation
and spectrum models, and offers the support for the investigation of future
wireless systems in ns-3.
