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.
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (118 CRs across 5 releases). Complements the general historical overview above with the evidence-based evolution of this function.
In Release 15, enhancements for WLAN integration included introducing support for Emergency services over WLAN and improving UE location description for IMS charging when connected over WLAN. The release also added procedures for the delivery and updating of local emergency numbers via NAS and enhanced location information reporting for both trusted and untrusted WLAN access. Furthermore, it introduced the collection of WLAN measurements for Minimization of Drive Tests (MDT) and clarified procedures for local PDU session release.
- 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
+ 32 more changes
In Release 16, the WLAN function introduced new procedures for a "5G capable over WLAN (N5CW) device," including its registration, session establishment, and session release. It also enhanced WLAN and PLMN selection procedures specifically for such N5CW devices and for trusted non-3GPP access. Furthermore, the release addressed session management aspects like local release during RRC inactive state and for Multi-Access PDU sessions.
- 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
- Correction of term "user preference" to "UE local configuration" for inter-system change without N26 TS 24.501CR1107
- Local release when receiving REFRESH command for routing indicator in RRC inactive TS 24.501CR1342
+ 3 more changes
In Release 17, enhancements for the WLAN function focused on refining local session management and device handling. Key additions included support for configuring Non-Seamless WLAN Offload (NSWO) via the USIM and improved procedures for local IP address handling during Traffic Flow Template (TFT) negotiation. The release also introduced corrections for the operation of non-5G capable devices over WLAN (N5CW) and for location configuration related to WLAN for Self-Organizing Network (SON) and Minimization of Drive Tests (MDT) features.
- Local deactivation of UP resource for an MA PDU session with PDN leg - 24501 Part TS 24.501CR3860
- UE MBS session local release at PDU session release TS 24.501CR3900
- UE Locally leaves the MBS session when the PDU session is released TS 24.501CR3921
- UE MBS session local leave when the 3GPP access UP resources are released TS 24.501CR4029
- Support of MC slicing configuration as part of UE local configuration TS 24.501CR4433
- 5G NSWO (Non-Seamless WLAN Offload) configuration support in the USIM compromised proposal. TS 31.102CR0946
+ 12 more changes
In Release 18, key WLAN enhancements focused on improving integration and policy control for 5G and SNPNs (Standalone Non-Public Networks). New mechanisms were introduced for WLAN discovery and selection procedures within SNPNs, along with enhanced support for localized services. Furthermore, the release specified Multi-Priority Service (MPS) features for WLAN, including enhancements for registration, transport priority, and congestion exemptions when connecting to 5G core networks.
- 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
- The enhancement on onboarding services in SNPN supporting localized services TS 24.501CR5087
+ 39 more changes
In Release 19, enhancements for WLAN interworking focused on improving the integration with Standalone Non-Public Networks (SNPNs) providing localized services, including mechanisms for ensuring appropriate cell reselection and managing UE registration states within these areas. The release also introduced corrections to the procedures for WLAN selection, specifically updating references to Manual mode and Automatic mode WLAN selection within the specifications. These updates refine the interaction between the 3GPP system and interworking WLANs (I-WLANs) in specialized network environments.
- Information for ensuring appropriate cell reselection for localized services in SNPN TS 24.501CR6486
- Mixture of two and three digit E.212 MNC codes within a single geographic MCC area shall instead be stated subject on local/regional regulations, i.e. shall be a national matter TS 23.003CR0716
- The recognition of SNPN providing access for localized services TS 24.501CR6456
- FTA list for localized services in SNPN with GIN TS 24.501CR6502
- Restrictions by local regulations for emergency service TS 24.501CR6949
- Local de-registration during unavailability period in 5G. TS 24.501CR6989
+ 2 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 |