RFC 7946

The GeoJSON Format
Standards Track
August 2016
RFC Library > Data Formats & Encoding > RFC 7946
Abstract: GeoJSON is a format for encoding geographic data structures using JSON. In 3GPP, GeoJSON is used in location services (LCS), geofencing for UE positioning (LMF), and network slice coverage area definitions in 5G.
Canonical source: https://www.rfc-editor.org/rfc/rfc7946  |  IETF Datatracker

1. Introduction

▶

GeoJSON encodes geographic features as JSON objects. A Feature has a geometry (point, line, polygon, etc.) and arbitrary properties. A FeatureCollection groups multiple Features.

In 3GPP 5GC, GeoJSON is used to represent UE positions in location service responses (Nlmf), define geographical service areas for network slices, specify cell coverage areas, and describe geofencing boundaries.

2. GeoJSON Geometry Types

▶
Type Description 3GPP Usage
Point Single position [longitude, latitude] UE location estimate
MultiPoint Array of positions Multiple candidate locations
LineString Array of positions forming a path Route/trajectory
Polygon Linear ring(s) defining an area Cell coverage area, geofence
MultiPolygon Array of polygons Network slice service area
GeometryCollection Heterogeneous geometry collection Complex coverage definitions

3. GeoJSON Example (UE Location)

▶ 
  {
"type": "Feature",
"geometry": {
"type": "Point",
"coordinates": [-73.9857, 40.7484]
},
"properties": {
"accuracy": 50,
"confidence": 95,
"altitude": 320,
"timestamp": "2024-01-15T10:30:00Z"
}
}
Cell Coverage Polygon:
{
"type": "Feature",
"geometry": {
"type": "Polygon",
"coordinates": [[
[-73.990, 40.745],
[-73.980, 40.745],
[-73.980, 40.752],
[-73.990, 40.752],
[-73.990, 40.745]
]]
},
"properties": {
"cellId": "460-00-0001-01",
"tac": 12345
}
}

4. Coordinate Reference System

▶
  • GeoJSON uses WGS 84 (EPSG:4326) as the coordinate reference system — same as GPS and 3GPP location services
  • Coordinate order is [longitude, latitude, altitude] — note: longitude first, not latitude
  • Altitude is optional and in meters above WGS 84 reference ellipsoid
  • Antimeridian crossing and polar regions require special handling

5. Security Considerations

▶
  • GeoJSON location data is privacy-sensitive — access control and encryption required
  • UE location must comply with regulatory requirements (lawful intercept, user consent)
  • Large GeoJSON objects (complex polygons) can be used for resource exhaustion — validate size
  • Precision of coordinates should be limited to prevent over-sharing of location accuracy