Assisted GNSS

A-GNSS works by providing the necessary data to the device via a radio network instead of the slow satellite link, essentially "warming up" the receiver for a fix.

For billing purposes, network providers often count this as a data access, which can cost money, depending on the tariff.

However, the availability of a data connection can provide assistance to improve the performance of the GPS chip on the mobile device.

Assistance falls into two categories: Not every A-GNSS server provides MSA mode operation due to the computational cost and the declining number of mobile terminals incapable of performing their own calculations.

A typical A-GPS-enabled receiver uses a data connection (Internet or other) to contact the assistance server for aGPS information.

The SUPL (Secure User Plane Location) protocol, unlike its control-plane equivalents restricted to mobile networks, runs on the Internet's TCP/IP infrastructure.

It includes:[6] The specifics of communication is defined in the ULP (Userplane Location Protocol) substandard of SUPL suite.