By default, none. You can install Google services, then your phone will use their proprietary NLP system.

You can also install microG (an application that pretends to be a Google service and connects to it, but sending minimal data, respecting your privacy) and then you will use MozillaNLP and DejaVuNLP at the same time.

MozillaNLP: you send a list of WiFi networks around you to Mozilla over the Internet, you get location data

DejaVuNLP: a local database built on your phone. When a GPS location signal is available, DejaVu fetches the list of WiFi networks and adds this list of networks corresponding to the given GPS coordinates to its database for later use