In view of the Large Hadron Collider (LHC) luminosity upgrades, the New Small Wheels (NSW) will replace the present Small Wheel stations of the ATLAS end-cap Muon Spectrometer. The aim of the NSW is to maintain the same level of efficiency, momentum threshold and resolution in the expected higher background level and to keep an acceptable muon trigger rate.
The NSW is equipped with two completely new detector technologies: the small-strip Thin Gap Chambers and the resistive-strip Micromegas. Currently the series production of the detectors is well advanced and the integration in sectors and assembly of the wheels is in progress. Quality control tests, including cosmic rays data taking are in full swing. The software for simulation and reconstruction of the NSW is also well advanced. The nominal geometries and misalignments are implemented, while the implementation of all other possible deviations from ideal operating conditions is ongoing. The detector's response simulation is underway with the aim to be compared with the real data collected from cosmic rays and test-beams. Finally, trigger and reconstruction performance studies are carried out in different configurations of the detectors and background levels. In this paper, an overview of the software implementation and the adopted strategies for simulation and reconstruction is presented. Furthermore, a summary of the real data studies for the future validation and comparison is given.