  Due to the rapid technology evolution and standardization activity in the
mobile communication networks, there is the need for the research community to
be able to develop, test and evaluate new and/or already xisting solutions
before industrial or real-network implementation. As such, it is essential to
have an open-source tool that provides an alternative solution to that of
industrial proprietary simulators that are not available for public usage. ns-3
5G-LENA simulator is an end-to-end open-source NR system-level simulator that
allows extensive research to be performed. However, it is of great importance
to guarantee that the results obtained using the simulator can be comparable to
that of industrial simulators and real networks. For this reason, calibrating
the simulator based on 3GPP defined specifications is crucial. Based on the
above, in this paper we calibrate the ns-3 5G-LENA simulator according to the
3GPP reference results for NR-based outdoor deployments. Moreover, we explore
the REM feature provided by the simulator, to ease the calibration process and
understand better the radio environment. Results show the resemblance of the
simulator performance to that of simulators used as references by 3GPP.
