Description
Wireless Local Area Network (WLAN), predominantly based on IEEE 802.11 standards (Wi-Fi), is a fundamental radio access technology for local area connectivity. Within the 3GPP ecosystem, WLAN is not defined as a 3GPP RAT itself, but its integration with 3GPP cellular networks is extensively standardized. This integration, known as WLAN Interworking or Access Network Discovery and Selection Function (ANDSF) in earlier releases, and later as Non-3GPP Interworking or Access Traffic Steering, Switching and Splitting (ATSSS) in 5G, allows User Equipment (UE) to utilize WLAN for IP connectivity, often in conjunction with cellular access.
Architecturally, 3GPP defines several interworking scenarios. For 3G and 4G, the core network interacts with WLAN via specific interfaces like S2a (for trusted WLAN access to the Packet Data Network Gateway - PGW) using protocols such as GTP or PMIPv6. Network entities like the ePDG (evolved Packet Data Gateway) provide secure IPsec tunnels for untrusted WLAN access. The ANDSF provides policies to the UE for network selection. In 5G, the Non-3GPP InterWorking Function (N3IWF) connects untrusted non-3GPP access (like public Wi-Fi) to the 5G Core, while trusted WLAN connects directly to the AMF/UPF. The 5G core treats WLAN as another access type, enabling seamless authentication (via 5G-AKA or EAP-AKA'), unified policy control, and session continuity.
How it works: A dual-mode UE discovers available WLAN networks and, based on operator policies (from ANDSF or UE policies), may attach to a WLAN Access Point. For trusted access, the UE authenticates using EAP-SIM/AKA/AKA' credentials, gaining IP connectivity routed through the cellular core network. User plane traffic can be offloaded locally at the WLAN (Local Breakout) or routed back to the core (Home Routed). Key 3GPP specs define authentication, mobility, policy control, and quality of service mechanisms to create a unified experience. Its role is to provide increased capacity, improve user data rates in dense areas, reduce cellular network congestion, and enable fixed-mobile convergence.
Purpose & Motivation
The integration of WLAN into 3GPP standards was motivated by the explosive growth of Wi-Fi and the need for cellular operators to leverage unlicensed spectrum to offload data traffic from congested macro cellular networks. Early cellular-WLAN interworking aimed to provide simple internet access, but the purpose evolved to offer seamless, secure, and policy-controlled access to operator services, creating a combined cellular-WLAN service fabric.
Historically, initial work in Release 6 defined loose coupling for basic interworking. Later releases addressed limitations like lack of seamless mobility, inconsistent security, and poor user experience when switching networks. The evolution towards tighter integration, with EPC and 5GC treating WLAN as a trusted access, solves problems of authentication transparency (using the same SIM credentials), seamless session continuity (e.g., via IFOM or ATSSS), and consistent application of operator policies and charging. This allows operators to manage WLAN as an integral part of their heterogeneous network (HetNet) strategy, improving overall network efficiency and user satisfaction.
Release Timeline
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (48 CRs across 5 releases). Complements the general historical overview above with the evidence-based evolution of this function.
In Release 15, enhancements for WLAN included the introduction of Bluetooth and WLAN measurement collection in Minimization of Drive Tests (MDT), corrections and clarifications to the WLAN selection procedure, and the enabling of emergency services over WLAN. It also added charging and location information enhancements for WLAN access, including parameters for WLAN-based ProSe direct discovery. Furthermore, the release addressed configuration for handover between WLAN and the Evolved Packet System (EPS) and PGW selection for WLAN when Dedicated Core Networks (DCNs) are deployed.
- Configuration parameter for handover between WLAN and EPS TS 31.102CR0768
- Add charging description for WLAN-based ProSe direct discovery TS 32.277CR0031
- Add CDR parameter for WLAN-based ProSe direct discovery TS 32.298CR0654
- Enhance location information in trusted and untrusted WLAN TS 32.298CR0658
- Introduce Emergency services over WLAN TS 32.298CR0659
- Enhance UE location description for IMS charging when over WLAN TS 32.298CR0662
+ 12 more changes
In Release 16, the new WLAN functions introduced procedures for a "5G capable over WLAN (N5CW) device" to perform registration, session establishment, and session release. It also defined enhanced WLAN and PLMN selection procedures for such devices when using trusted non-3GPP access. Furthermore, it specified mechanisms for user access control (UAC) checks for services that begin on WLAN and are subsequently transferred to 3GPP access.
- Update to WLAN selection procedure because of trusted non-3GPP access TS 24.502CR0075
- TNAN and PLMN selection procedures using trusted WLAN TS 24.502CR0084
- Registration, Session establishment and session release of 5G capable over WLAN (N5CW) device TS 24.502CR0100
- WLAN and PLMN selection procedures for a N5CW device TS 24.502CR0106
- UAC check for services started in WLAN and being transferred to 3GPP access TS 24.501CR1349
In Release 17, the WLAN function saw enhancements focused on Non-Seamless WLAN Offload (NSWO) configuration support within the USIM and refinements for non-5G capable over WLAN (N5CW) devices, including term additions and procedural corrections. Furthermore, a correction was made to the location configuration procedures for WLAN (and Bluetooth) specifically for SON and MDT features. These updates provided more precise management for WLAN interworking and device capabilities within the 3GPP system framework.
- 5G NSWO (Non-Seamless WLAN Offload) configuration support in the USIM compromised proposal. TS 31.102CR0946
- Addition to the non 5G capable over WLAN (N5CW) device term TS 24.501CR2945
- Correction to procedures for non 5G capable over WLAN (N5CW) devices TS 24.502CR0175
- Correction on location configuration for WLAN and BT for SON and MDT features TS 36.331CR4958
In Release 18, the enhancements for WLAN functions primarily focused on expanding support for Multi-Purpose Subscriber (MPS) features and refining procedures for Standalone Non-Public Networks (SNPN). Key additions included MPS capabilities for WLAN NAI augmentation and decoration, congestion exemptions, and transport priority for both EPC and 5G Core networks. The release also introduced new WLAN discovery and selection procedures specifically for SNPNs and for 5G Non-Seamless WLAN Offload (NSWO) using SNPN credentials.
- MPS for WLAN NAI augmentation TS 23.003CR0693
- MPS for WLAN EPC congestion exemptions for MCM TS 24.244CR0058
- MPS for WLAN EPC congestion exemptions TS 24.302CR0754
- MPS for WLAN EPC Transport Priority TS 24.302CR0752
- MPS for WLAN EPC attach TS 24.302CR0753
- WLAN discovery and selection procedure in SNPN TS 24.502CR0216
+ 14 more changes
Explore further
Broader topics and technologies where WLAN plays a role.
Defining Specifications
3GPP specifications that define or reference WLAN, 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 22.234 vd10 | 3GPP-WLAN Interworking Index Specification | Rel-13 |
| TS 22.240 vj00 | 3GPP Generic User Profile Requirements | Rel-19 |
| TS 22.811 v1700 | Network Selection Mechanisms Overview | Rel-7 |
| TR 22.813 va00 | Enhanced Voice Services for EPS Study | Rel-10 |
| TR 22.906 vj00 | IMS P2P Content Distribution Services | Rel-19 |
| TR 22.949 vj00 | Privacy Requirements Study for 3GPP Services | Rel-19 |
| TR 22.980 vj00 | Network Composition Feasibility Study | Rel-19 |
| TS 23.003 vj50 | Numbering, addressing and identification in 3GPP | Rel-19 |
| TS 23.125 v1700 | Flow Based Charging Architecture | Rel-7 |
| TS 23.141 vj00 | Presence Service Stage 2 Architecture | Rel-19 |
| TS 23.167 vj11 | IMS Emergency Sessions | Rel-19 |
| TS 23.179 vd50 | MCPTT Functional Architecture | Rel-13 |
| TS 23.234 vd10 | 3GPP-WLAN Interworking Index | Rel-13 |
| TS 23.280 vk10 | Common Architecture for Mission Critical Services | Rel-20 |
| TS 23.379 vk00 | MCPTT Functional Architecture | Rel-20 |
| TS 23.380 vj10 | IMS Restoration Procedures | Rel-19 |
| TS 23.806 v1700 | Voice Call Continuity between CS and IMS | Rel-7 |
| TS 23.826 v900 | Voice Call Continuity for Emergency Calls | Rel-9 |
| TR 23.976 vj00 | Push Service Requirements Analysis | Rel-19 |
| TS 24.161 vj00 | Network-Based IP Flow Mobility (NBIFOM) | Rel-19 |
| TS 24.206 v1700 | Voice Call Continuity Between CS and IMS | Rel-7 |
| TS 24.229 vj50 | IMS call control protocol based on SIP and SDP | Rel-19 |
| TS 24.234 vc20 | 3GPP-WLAN Interworking Network Selection | Rel-12 |
| TS 24.244 vj00 | Wireless LAN Control Plane Protocol | Rel-19 |
| TS 24.302 vj00 | Access to EPC via non-3GPP networks; Stage 3 | Rel-19 |
| TS 24.484 vj30 | MCS Configuration Management | Rel-19 |
| TS 24.501 vj50 | 5G NAS Protocols Specification | Rel-19 |
| TS 24.502 vj20 | 5G Core Access via Non-3GPP Networks; Stage 3 | Rel-19 |
| TS 25.300 vj00 | UTRA Radio Interface Enhancements Overview | Rel-19 |
| TS 25.305 vj00 | UTRAN UE Positioning Stage 2 | Rel-19 |
| TS 25.306 vj00 | UE Radio Access Capabilities Specification | Rel-19 |
| TS 25.331 vj00 | UTRAN RRC Protocol Specification | Rel-19 |
| TS 25.453 vj00 | PCAP Protocol Specification | Rel-19 |
| TS 26.131 vj00 | Terminal Acoustic Performance Requirements | Rel-19 |
| TS 26.132 vj00 | Terminal Acoustic Test Methods | Rel-19 |
| TS 26.261 vj00 | Electro-acoustic specs for immersive terminals | Rel-19 |
| TR 26.938 vj00 | DASH Deployment Guidelines for 3GPP Networks | Rel-19 |
| TS 28.680 vj00 | WLAN Management Concepts and Requirements | Rel-19 |
| TS 28.681 vj00 | WLAN Management NRM IRP Requirements | Rel-19 |
| TS 28.682 vj00 | WLAN Management NRM IRP Information Service | Rel-19 |
| TS 28.683 vj00 | WLAN NRM IRP Solution Set Definitions | Rel-19 |
| TS 29.161 vc00 | 3GPP-WLAN Interworking Requirements | Rel-12 |
| TS 29.234 vb20 | WLAN-3GPP Interworking Stage-3 Protocol | Rel-11 |
| TS 31.102 vj40 | USIM Application Specification | Rel-19 |
| TS 32.103 vj00 | 3GPP Management IRP Overview | Rel-19 |
| TS 32.240 vj40 | Charging Management Architecture & Principles | Rel-19 |
| TS 32.252 vc00 | 3GPP WLAN Interworking Charging | Rel-12 |
| TS 32.272 vj00 | Charging for Push-to-Talk over Cellular (PoC) | Rel-19 |
| TS 32.277 vj20 | Charging Management for Proximity Services (ProSe) | Rel-19 |
| TS 32.296 vj00 | Online Charging System (OCS) Architecture | Rel-19 |
| TS 32.297 vj00 | Charging Data Record File Transfer | Rel-19 |
| TS 32.298 vj30 | Charging Data Record (CDR) Parameter Specification | Rel-19 |
| TS 33.106 vj00 | Lawful Interception Requirements (Pre-Rel-15) | Rel-19 |
| TS 33.107 vj00 | Lawful Interception Architecture & Functions | Rel-19 |
| TS 33.234 vj00 | 3GPP-WLAN Interworking Security | Rel-19 |
| TS 33.812 v920 | M2M Remote Subscription Management Security | Rel-9 |
| TS 33.814 vg01 | Security aspects of enhanced Location Services (eLCS) | Rel-16 |
| TS 36.300 vj00 | E-UTRAN Radio Interface Protocol Architecture Overview | Rel-19 |
| TS 36.305 vj00 | UE Positioning in E-UTRAN Stage 2 | Rel-19 |
| TS 36.306 vj00 | E-UTRA UE Radio Access Capability Parameters | Rel-19 |
| TS 36.331 vj00 | LTE RRC Protocol Specification | Rel-19 |
| TS 36.355 vj00 | LTE Positioning Protocol (LPP) | 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 36.896 ve00 | Study on Flexible eNB-ID and Cell-ID in E-UTRAN | Rel-14 |
| TS 37.171 vj00 | UE Positioning Performance Requirements | Rel-19 |
| TS 37.355 vj20 | LTE Positioning Protocol (LPP) | Rel-19 |
| TS 37.544 vg70 | UE Radiated Performance Test Procedures | Rel-16 |
| TS 37.571 vj00 | UE Conformance for Positioning | Rel-19 |
| TS 37.834 vc00 | WLAN/3GPP Radio Interworking Study | Rel-12 |
| TS 38.305 vj00 | NG-RAN UE Positioning Stage 2 | Rel-19 |
| TS 38.306 vj00 | NR UE Radio Access Capability Parameters | Rel-19 |
| TS 38.855 vg00 | Study on NR Positioning Support | Rel-16 |
| TR 38.913 vj00 | Next Gen Access Tech Scenarios & Requirements | Rel-19 |
