Description
Global Navigation Satellite System (GNSS) is a generic term encompassing all satellite-based positioning systems, including GPS (USA), Galileo (EU), GLONASS (Russia), and BeiDou (China). Within 3GPP specifications, GNSS is integrated as a key method for determining the geographical location of User Equipment (UE). The architecture involves the UE containing a GNSS receiver capable of processing signals from one or multiple satellite constellations. The network can assist this process through control plane or user plane location protocols, such as LTE Positioning Protocol (LPP) or Secure User Plane Location (SUPL), by providing aiding data like ephemeris, almanac, and approximate location to reduce the UE's Time To First Fix (TTFF) and improve accuracy.
The fundamental operation relies on the UE measuring the time of arrival of signals from multiple visible satellites. By calculating the signal travel time and knowing the satellite positions (from decoded or network-provided navigation messages), the UE can compute its own three-dimensional position and precise time through trilateration. Key components include the satellite constellations themselves, the UE's GNSS receiver and antenna, and network elements like the Location Management Function (LMF) in 5GC or the Enhanced Serving Mobile Location Centre (E-SMLC) in EPS, which manage the positioning session and calculations.
GNSS positioning in 3GPP supports multiple modes: standalone (UE operates independently using only satellite signals), UE-assisted (UE sends measurements to the network for position calculation), and UE-based (UE calculates its own position, potentially using network-provided assistance data). Its role is critical for emergency services (e.g., E911/E112), location-based services, lawful interception, network optimization (e.g., for mobility management), and various IoT applications requiring asset tracking. The specifications detail requirements for performance (accuracy, sensitivity), testing, and integration with radio access technologies from UMTS to 5G NR.
Purpose & Motivation
The primary purpose of integrating GNSS into 3GPP standards is to provide a reliable, globally available method for determining UE location. This addresses regulatory mandates for emergency caller location (e.g., FCC E911 in the USA, E112 in the EU), which require mobile networks to provide accurate position information for emergency calls. It also enables a vast ecosystem of commercial location-based services (LBS), such as navigation, fleet management, and location-aware applications, creating new revenue streams for operators.
Historically, cellular-only positioning methods like Cell-ID, Enhanced Cell-ID, and Observed Time Difference of Arrival (OTDOA) had limitations in accuracy, especially in rural or sparse cell deployment areas. GNSS provides superior outdoor accuracy, often down to a few meters, filling this gap. Its inclusion starting in 3GPP Release 7 formalized the support for assisted-GNSS (A-GNSS), which leverages the network to deliver assistance data to the UE, significantly improving startup performance (TTFF), sensitivity (allowing fixes in weaker signal conditions), and UE battery life compared to standalone GNSS operation.
The motivation extended beyond compliance and services to network optimization and new use cases. Accurate location aids in radio resource management, handover decisions, and network planning. For later technologies like V2X and IoT, precise GNSS-based timing and positioning are foundational. The evolution to support multiple constellations (multi-GNSS) and hybrid positioning (combining GNSS with terrestrial signals) in subsequent releases was driven by the need for improved availability, robustness in urban canyons, and even higher accuracy for advanced applications like autonomous driving and industrial automation.
Classification
Release Timeline
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (47 CRs across 5 releases). Complements the general historical overview above with the evidence-based evolution of this function.
In Release 15, the specification work introduced and refined requirements for Assisted GNSS (A-GNSS) operation in New Radio (NR) networks. This involved a dedicated Change Request for A-GNSS in the performance requirements specification (TS 38.171). Furthermore, a subsequent correction CR was processed to address and rectify specific A-GNSS requirements for NR.
In Release 16, key enhancements for GNSS included the introduction of support for the BeiDou B1C signal and an update to the B1I signal Interface Control Document (ICD) to version 3.0 within the Assisted-GNSS (A-GNSS) framework. The release also introduced support for GNSS Integer Ambiguity Level Indications and added definitions for frequency bands used for testing A-GNSS sensitivity requirements. Furthermore, clarifications were made to the meaning of the term "GNSS" within the core network specifications.
- CR for TS36.171, Introduction of BDS B1C in A-GNSS TS 36.171CR0020
- Introduction of B1C signal in BDS system in A-GNSS TS 36.305CR0083
- Introduction of B1C signal in BDS system in A-GNSS TS 37.355CR0248
- Introducing support for GNSS Integer Ambiguity Level Indications TS 37.355CR0252
- CR for TS38.171, Introduction of BDS B1C in A-GNSS TS 38.171CR0011
- Introduction of B1C signal in BDS system in A-GNSS TS 38.305CR0013
+ 7 more changes
In Release 17, key GNSS enhancements included the introduction of support for new signals, specifically the B2a and B3I signals for the BDS (BeiDou) system and the L5 signal for the NavIC system, to improve A-GNSS capabilities. The release also introduced the provision of high-accuracy GNSS location estimates, including NMEA GGA sentence information, and made various corrections and clarifications to integrity bounds, orbit ephemeris references, and field descriptions for SSR (State Space Representation) data across several technical specifications.
- Introduction of B2a and B3I signal in BDS system and GNSS Positioning Integrity TS 36.305CR0107
- NMEA GGA sentence info in high accuracy GNSS location estimates [HA-GNSS-NMEA] TS 37.355CR0349
- RRC Correction on including GNSS validity duration and dedicated SIB31 TS 36.331CR4952
- Correction on the GNSS Orbit and Clock Integrity Bounds in TS 37.355 TS 37.355CR0377
- GNSS SSR BDS orbit emphemeris reference clarification to align with RTCM TS 37.355CR0461
- Field description correction for HA-GNSS metrics TS 37.355CR0474
+ 9 more changes
In Release 18, enhancements for GNSS primarily focused on improving positioning accuracy through the introduction of assistance information for Line-of-Sight (LOS) and Non-Line-of-Sight (NLOS) conditions, including its broadcast via posSIB. The release also included corrections to existing GNSS procedures, RIL (Radio Interface Layer) implementations for LOS/NLOS, and specific data structures like the NavIC almanac set and A-GNSS positioning parameters.
- GNSS LOS/NLOS posSIB broadcast assistance information [GNSS LOS/NLOS] TS 36.331CR4931
- GNSS LOS/NLOS assistance information [GNSS LOS/NLOS] TS 37.355CR0446
- GNSS LOS/NLOS posSIB broadcast assistance information [GNSS LOS/NLOS] TS 38.331CR4109
- Correction on GNSS procedure TS 36.331CR5101
- Miscellaneous RIL corrections for GNSS LOS/NLOS [GNSS LOS/NLOS] TS 37.355CR0495
- Correction on GNSS-AlmanacSupport and GNSS-UTC-ModelSupport in A-GNSS positioning TS 37.355CR0518
+ 1 more changes
In Release 19, 3GPP expanded A-GNSS support by introducing assistance data for the BeiDou B2b signal and the NavIC L1 SPS signal across LTE, NR, and the LPP specification. The release also introduced a new UE capability to request equalIntegerAmbiguityLevel assistance data and included miscellaneous corrections for LPP procedures.
- CR for TS 36.171 to introduce BDS B2b signal in A-GNSS TS 36.171CR0032
- Introduction of NavIC L1 SPS A-GNSS in LTE Stage 2 specification TS 36.305CR0120
- Introduction of BDS B2b in A-GNSS TS 36.305CR0121
- Introduction of NavIC L1 SPS A-GNSS in LPP TS 37.355CR0532
- Introduction of B2b signal in BDS system in A-GNSS TS 37.355CR0545
- UE request for equalIntegerAmbiguityLevel assistance data [GNSS-EqualIntegerAmbiguity] TS 37.355CR0557
+ 4 more changes
Explore further
Broader topics and technologies where GNSS plays a role.
Defining Specifications
3GPP specifications that define or reference GNSS, with the latest known release. Sourced from the 3GPP document catalog — see methodology.
| Specification | Title | Release |
|---|---|---|
| TR 21.905 vj00 | 3GPP Technical Terms and Definitions | Rel-19 |
| TS 22.071 vj00 | 3GPP TS 22.071: Location Services (LCS) Stage 1 | Rel-19 |
| TR 22.867 vi20 | Study on 5G Smart Energy and Infrastructure | Rel-18 |
| TR 22.889 vh40 | FRMCS Study; Stage 1 | Rel-17 |
| TR 22.989 vk30 | FRMCS Analysis and Requirements | Rel-20 |
| TS 23.271 vj00 | LCS Stage 2 Specification | Rel-19 |
| TR 23.744 vh10 | Location Enhancements for Mission Critical Services | Rel-17 |
| TS 25.172 vj00 | A-GANSS UE Minimum Performance Requirements (FDD) | Rel-19 |
| TS 25.173 vj00 | A-GANSS Performance Requirements (TDD) | Rel-19 |
| TS 25.215 vj00 | UTRA FDD Measurement Definitions | Rel-19 |
| TS 25.302 vj00 | UTRA Physical Layer Services | Rel-19 |
| TS 25.305 vj00 | UTRAN UE Positioning Stage 2 | Rel-19 |
| TS 25.331 vj00 | UTRAN RRC Protocol Specification | Rel-19 |
| TS 25.423 vj00 | UTRAN RNSAP Specification | Rel-19 |
| TS 25.433 vj00 | Node B Application Part (NBAP) Protocol | Rel-19 |
| TS 25.450 vj00 | Iupc Interface Introduction for UTRAN Positioning | Rel-19 |
| TS 25.453 vj00 | PCAP Protocol Specification | Rel-19 |
| TS 25.467 vj00 | UTRAN Architecture for 3G Home Node B | Rel-19 |
| TR 25.912 vj00 | Evolved UTRA and UTRAN Technical Report | Rel-19 |
| TS 26.851 vb20 | Enhancements to Multimedia (EMM) for PSS, MMS, MBMS | Rel-11 |
| TR 26.928 vj00 | Study on eXtended Reality (XR) in 5G | Rel-19 |
| TS 28.628 vj00 | SON Policy NRM IRP Information Service | Rel-19 |
| TS 29.171 vj00 | LCS Application Protocol (LCS-AP) Specification | Rel-19 |
| TS 32.836 vc00 | NM Centralized Coverage and Capacity Optimization Study | Rel-12 |
| TS 33.320 vj00 | H(e)NB Subsystem Security Architecture | Rel-19 |
| TS 34.171 v1940 | A-GPS FDD UE Conformance Testing Procedures | Rel-9 |
| TS 34.172 va20 | A-GNSS Conformance Testing for UTRA FDD UE | Rel-10 |
| TS 36.101 vj30 | LTE UE Radio Transmission & Reception Requirements | Rel-19 |
| TS 36.171 vj10 | A-GNSS Minimum Performance Requirements for UE | Rel-19 |
| TS 36.214 vj00 | E-UTRA Physical Layer Measurements | Rel-19 |
| TS 36.300 vj00 | E-UTRAN Radio Interface Protocol Architecture Overview | Rel-19 |
| TS 36.302 vj00 | E-UTRA Physical Layer Services | Rel-19 |
| TS 36.305 vj00 | UE Positioning in E-UTRAN Stage 2 | Rel-19 |
| TS 36.331 vj00 | LTE RRC Protocol Specification | Rel-19 |
| TS 36.355 vj00 | LTE Positioning Protocol (LPP) | Rel-19 |
| TS 36.413 vj10 | S1 Application Protocol (S1AP) | Rel-19 |
| TS 36.423 vj10 | X2 Application Protocol (X2AP) Specification | Rel-19 |
| TS 36.455 vj00 | LTE Positioning Protocol Annex (LPPa) | Rel-19 |
| TR 36.791 vg00 | E-UTRA 2.4 GHz TDD Band for US | Rel-16 |
| TS 36.816 vb20 | In-device coexistence interference avoidance | Rel-11 |
| TS 37.320 vj00 | Minimization of Drive Tests (MDT) Overview | Rel-19 |
| TS 37.355 vj20 | LTE Positioning Protocol (LPP) | Rel-19 |
| TS 37.571 vj00 | UE Conformance for Positioning | Rel-19 |
| TS 37.718 | 3GPP TR 37.718 | Rel-7 |
| TS 37.719 vj00 | 3GPP TR 37.719: Dual Connectivity Band Combinations | Rel-19 |
| TS 37.863 | 3GPP TR 37.863 | Rel-7 |
| TS 38.171 vj10 | 5G A-GNSS UE Positioning Requirements | Rel-19 |
| TS 38.215 vj10 | NR Physical Layer Measurements | Rel-19 |
| TS 38.300 vj00 | NG-RAN Overall Description | Rel-19 |
| TS 38.305 vj00 | NG-RAN UE Positioning Stage 2 | Rel-19 |
| TS 38.331 vj00 | NR Radio Resource Control (RRC) Protocol Specification | Rel-19 |
| TS 38.455 vj10 | NR Positioning Protocol A (NRPPa) | Rel-19 |
| TS 38.811 vf40 | Study on NR Support for Non-Terrestrial Networks | Rel-15 |
| TS 38.855 vg00 | Study on NR Positioning Support | Rel-16 |
| TR 38.859 vi10 | Technical Report | Rel-18 |
| TR 38.882 vi00 | Technical Report on UE Location Service | Rel-18 |
| TR 38.889 vg00 | NR-based access to unlicensed spectrum study | Rel-16 |
| TR 38.913 vj00 | Next Gen Access Tech Scenarios & Requirements | Rel-19 |
| TS 43.059 vj00 | GERAN LCS Stage 2 Specification | Rel-19 |
| TS 44.031 vj00 | Radio Resource LCS Protocol (RRLP) | Rel-19 |
| TS 51.010 vj00 | SIM Application Toolkit Conformance Testing | Rel-19 |
