Description
The WLAN Specific Identifier (WSID) is a subscription identifier defined within the 3GPP framework to facilitate interworking between 3GPP cellular networks and non-3GPP access networks, specifically WLANs. It is stored within the Universal Subscriber Identity Module (USIM) and is used by the network to uniquely identify a user's subscription for WLAN-specific procedures. The primary architectural role of the WSID is within the authentication and authorization framework, where it may be used in conjunction with or as an alternative to other identifiers like the IMSI, particularly in scenarios defined by the Wireless LAN Interworking (I-WLAN) specifications.
Operationally, the WSID is utilized during the Extensible Authentication Protocol (EAP) authentication process when a User Equipment (UE) attempts to attach to a WLAN that is integrated with the 3GPP core network. The network, specifically the Authentication, Authorization, and Accounting (AAA) server, can use the WSID to retrieve the correct subscriber profile and authentication credentials from the Home Subscriber Server (HSS). This process is detailed in specifications such as TS 24.234 (3GPP system to Wireless Local Area Network (WLAN) interworking) and TS 31.102 (Characteristics of the Universal Subscriber Identity Module (USIM) application).
Key components involving the WSID include the USIM where it is stored, the UE's WLAN stack that presents it during authentication, and the network's AAA infrastructure and HSS that process it. Its role is pivotal in enabling a standardized, secure method for cellular operators to extend their services and billing models to Wi-Fi hotspots, ensuring that the user experience is consistent and managed under the operator's policy framework. The identifier helps decouple WLAN access authentication from the core cellular identity, providing flexibility in service offering.
Purpose & Motivation
The WSID was introduced to address the growing need for seamless and secure integration between cellular networks and WLANs. Prior to its standardization, operators lacked a consistent, standardized method to identify and authenticate their subscribers on Wi-Fi networks, leading to fragmented user experiences and complex, proprietary authentication mechanisms. The creation of the WSID was motivated by the 3GPP's work on I-WLAN in Release 6, which aimed to define a unified architecture for interworking.
The technology solves the problem of subscriber identity management in heterogeneous access environments. By providing a WLAN-specific identifier stored on the USIM, it allows operators to leverage the existing SIM-based security infrastructure for WLAN access. This approach addressed limitations such as the need for separate usernames/passwords for Wi-Fi and enabled tighter integration with the operator's core network for services like authentication, authorization, and charging. It formed a foundational element for early network convergence efforts.
Classification
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (40 CRs across 5 releases). Complements the general historical overview above with the evidence-based evolution of this function.
Studied in Rel-6, normative work from Rel-15.
In Release 15, the WLAN Specific Identifier (WSID) function was not newly introduced based on the provided Change Request titles. The listed updates for this release focus on enhancing USIM capabilities for 5G, such as 5G authentication key storage, call control procedures, and configuration data for services like Mission Critical Services, but do not mention WSID.
- Subscription identifier privacy suppport TS 31.102CR0778
- USIM Service Table update for PDU session call control support TS 31.102CR0786
- Allow configuration of MCS (Access Identity 2) via USIM. TS 31.102CR0794
- Mission Critical Services configuration data update to USIM TS 31.102CR0808
- Fix implementation error for USIM Call Control procedure and allow updating only the operator specific ePCOs. TS 31.111CR0694
- Enhance USIM OPL configuration to support 3 bytes TAC when in NG-RAN. TS 31.102CR0818
+ 7 more changes
In Release 16, the WSID function was enhanced to allow the USIM to configure lists for network selection and user policies. Specifically, new capabilities were introduced for the USIM to store a list of Trusted non-3GPP access networks and to configure PS Data Off lists for both home and roaming scenarios. These additions provided the USIM with greater control over WLAN access and data usage management.
- Support for USIM configuration of RLOS PLMN list TS 31.102CR0847
- URSP storage in USIM TS 31.102CR0861
- Specify storage for a potentially separate KSEAF for non-3gpp access on the USIM TS 31.102CR0864
- USIM configuration of RLOS allowed MCC list TS 31.102CR0881
- Support for Trusted non-3GPP access networks list by USIM TS 31.102CR0891
- Dedicated AID for USIM Applications with non-IMSI based SUPI Types TS 31.102CR0897
+ 4 more changes
In Release 17, the WSID function was enhanced with new USIM-based configuration support for 5G Non-Seamless WLAN Offload (NSWO). Specifically, this release introduced a USIM file to store the 5G NSWO configuration and added a dedicated procedure for updating this configuration in the USIM.
- Introduce a USIM file to store pre-configured CAG information list TS 31.102CR0904
- SOR-CMCI storage in USIM TS 31.102CR0917
- Addition of USIM files for the indication of whether disaster roaming is enabled in the UE, disaster roaming wait range, disaster return wait range and applicability indicator for disaster roaming PLMNs list provided by VPLMN. TS 31.102CR0938
- Adding eDRX parameters in the USIM for NG-RAN TS 31.102CR0943
- 5G NSWO (Non-Seamless WLAN Offload) configuration support in the USIM compromised proposal. TS 31.102CR0946
- Support of 'No E-UTRA Disabling In 5GS' in USIM TS 31.102CR0947
+ 4 more changes
In Release 18, the WSID function was enhanced through the addition of a new Elementary File (EF) for Access Control to GBA_U_APIs on the USIM. This change specifically extended the storage and management of security parameters related to WLAN access. Furthermore, the release included corrections and alignments, such as a correction to the DF Identifier for 5MBSUECONFIG, to ensure consistency within the overall security architecture.
- 5G Security Parameters extended storage on USIM (Mandating Service n°133 to be enabled when Service n°123 is enabled) Rel18. TS 31.102CR1014
- Add EF of Access Control to GBA_U_APIs to the USIM TS 31.102CR1007
- Add EF of IMS Data Channel configuration to the USIM TS 31.102CR1006
- Correction of DF Identifier for 5MBSUECONFIG TS 31.102CR0984
- Alignment to latest ETSI SET specifications TS 31.102CR1038
In Release 19, the WSID function was enhanced to ensure backward compatibility for USIMs that lack extended security parameter storage in the EF_5GAuthKeys file. Additionally, updates were made to the identifier tags for both the E-UTRAN and NG-RAN Tracking Area Identification (TAI) lists as specified in clause 9.3.
Explore further
Broader topics and technologies where WSID plays a role.
Defining Specifications
3GPP specifications that define or reference WSID, with the latest known release. Sourced from the 3GPP document catalog — see methodology.
| Specification | Title | Release |
|---|---|---|
| TS 24.234 vc20 | 3GPP-WLAN Interworking Network Selection | Rel-12 |
| TS 31.102 vj40 | USIM Application Specification | Rel-19 |
| TS 31.111 vj30 | USIM Application Toolkit (USAT) Specification | Rel-19 |