NATS Antenna Amp.
WARNING: This page is about a different car, the 2016 Nissan Rogue. However, it is still accessible from the selected car via links, so may be relevant.
The ID verification is performed between BCM and transponder integrated into key via NATS antenna amp. when key backside is contacted to ignition switch in case that key battery is discharged. If the ID verification result is OK, the operation of ignition switch is available.