Understanding the assistance response

A successful request to the GET /v2/assistance endpoint returns A-GNSS data
for the requested GNSS systems.

The response format depends on the encoding query parameter:
UPER (default) returns a binary multipart/mixed response, while JER returns
LPP messages in JSON format. For full details on encoding formats, content types,
and message structure, see Response encoding and formats.

Response headers

Response body

The response contains one LPP message per requested GNSS system.

UPER example

--boundary
Content-Type: application/octet-stream
X-Constellation: gps

<binary LPP message for GPS>
--boundary
Content-Type: application/octet-stream
X-Constellation: gal

<binary LPP message for Galileo>
--boundary--

JER example (application/json)

{
  "assistance": {
    "messages": [
      {
        "gnss": "gps",
        "lpp": {
          "gnss-CommonAssistData": {
            "gnss-ReferenceTime": {...},
            "gnss-IonosphericModel": {...}
          },
          "gnss-GenericAssistData": [
            {
              "gnss-ID": { "gnss-id": "gps" },
              "gnss-TimeModels": [...],
              "gnss-NavigationModel": {...},
              "gnss-Almanac": {...},
              "gnss-UTC-Model": {...},
              "gnss-AuxiliaryInformation": {...}
            }
          ]
        }
      }
    ]
  }
}

Partially unavailable data

If assistance data for a particular GNSS system is temporarily unavailable,
the response still includes an entry for that system, but with an error indication:

• UPER: The corresponding multipart part includes the X-GNSS-Error header
  (for example, currentlyNotAvailable) and the binary body contains an LPP message where
  the A-GNSS-ProvideAssistanceData section includes only the gnss-Error field.
• JER: The corresponding message object's lpp field contains gnss-Error
  instead of the normal data elements.

UPER example with partially unavailable data:

--boundary
Content-Type: application/octet-stream
X-Constellation: gps

<binary LPP message for GPS>
--boundary
Content-Type: application/octet-stream
X-Constellation: gal
X-GNSS-Error: currentlyNotAvailable

<binary LPP message with gnss-Error for Galileo>
--boundary--

Related information

• Response encoding and formats
• Assistance data request
• Understanding the prediction response
• LPP ASN.1 schema