  As the specification of the new 5G NR standard proceeds inside 3GPP, the
availability of a versatile, full-stack, End-to-End (E2E), and open source
simulator becomes a necessity to extract insights from the recently approved
3GPP specifications. This paper presents an extension to ns-3, a well-known
discrete-event network simulator, to support the NR Radio Access Network. The
present work describes the design and implementation choices at the MAC and PHY
layers, and it discusses a technical solution for managing different bandwidth
parts. Finally, we present calibration results, according to 3GPP procedures,
and we show how to get E2E performance indicators in a realistic deployment
scenario, with special emphasis on the E2E latency.
