GNSS v2 Assistance Data

GNSS assistance data is used to improve the time to the first fix (TTFF). It also allows the GNSS device to achieve continuous position tracking with much weaker signal levels.

GNSS assistance data provides navigation models to the receiver, so that the initial search for satellites can be performed more accurately and satellite signals can be found faster.

Acquiring assistance data using the HERE GNSS Data API completely removes the need to receive the navigation message from the satellite and, therefore, improves the TTFF of the device, typically down to a few seconds.

In addition, assistance data includes, for example, ionospheric data and real-time information about the health of the satellites.

The HERE GNSS Data API provides A-GNSS data for the following satellite systems:

The format of GNSS assistance data follows the LPP 18.3.0 ASN.1 schema. The LPP data is encoded using ASN.1 Unaligned Packed Encoding Rules (UPER). See LPP ASN.1 schema for more information on the LPP schema.

Supported data elements

The following table lists the supported A-GNSS data elements and the constellations for which they are available - X indicates the element is available for that constellation.

Related information

• Assistance data request
• Understanding the response
• LPP ASN.1 schema