Description
A Local Area Data Network (LADN) is a 5G system feature defined from 3GPP Release 15 onwards. It enables the provisioning of a Data Network (DN) that is accessible to a User Equipment (UE) only when the UE is located within a specific geographical area, known as the LADN service area. This is a key enabler for localized services such as private networks, industrial IoT, and campus networks. The core network, specifically the Access and Mobility Management Function (AMF), is responsible for managing the UE's registration and session establishment context with respect to LADN availability. When a UE registers with the network, the AMF provides it with a list of configured LADNs and their corresponding service areas. The UE uses this information to determine its eligibility to access a particular LADN based on its current location.
The architecture involves the AMF, the Session Management Function (SMF), and the User Plane Function (UPF). The AMF stores the LADN configuration, including the Data Network Name (DNN) and the associated service area, which is defined as a set of Tracking Areas (TAs). When a UE initiates a Protocol Data Unit (PDU) Session establishment request for a LADN DNN, the AMF checks the UE's reported location against the LADN service area. If the UE is outside the area, the AMF rejects the session establishment, preventing unnecessary resource allocation and signaling. If inside, the request is forwarded to the SMF, which proceeds with normal PDU Session establishment procedures, potentially selecting UPFs that are local to the LADN for optimal routing.
LADN works by integrating location awareness into the core network's session management logic. The UE is not required to continuously monitor its location for LADN purposes; instead, it relies on the network's registration area updates and the AMF's knowledge. The service area is configured in the network and provided to the UE via non-access stratum (NAS) signaling. This mechanism ensures that PDU Sessions for a LADN are only active when the UE is within the designated zone, and they are deactivated or become inaccessible when the UE moves out. This model supports efficient network slicing for localized services, as a network slice instance can be associated with a specific LADN, ensuring resources are utilized only where needed.
Key components include the LADN DNN, which is a special DNN identifier, and the LADN service area definition. The AMF's role is central, as it performs the authorization check. The SMF is responsible for managing the PDU Session context and interacting with the Policy Control Function (PCF) and UPF. From a UE perspective, LADN awareness involves storing the received service area information and using it to conditionally attempt PDU Session establishment. This feature is crucial for enabling 5G to support vertical industry applications that require bounded, low-latency connectivity within a confined geographical footprint without impacting the wider public network.
Purpose & Motivation
LADN was created to address the need for efficient, geographically restricted data services in 5G networks. Prior to 5G, providing localized network access (like a private corporate network) often required overarching network configurations or dedicated infrastructure that wasn't tightly integrated with the mobile core. This could lead to inefficient use of core network resources, as sessions might be maintained even when a user was far from the service location, causing unnecessary signaling and user plane traffic across the network.
The motivation stems from the 5G vision to support diverse industry verticals, such as smart factories, ports, and campuses. These environments require guaranteed, high-performance connectivity that is logically and physically confined to a specific area. LADN solves this by making the core network itself area-aware, allowing it to dynamically grant or deny access to a specific data network based on real-time user location. This solves the problem of network resource sprawl and enables true network slicing for localized services, where a slice's resources are only consumed when a user is physically present in the relevant area. It provides a standardized, core-network-native method for service area restriction, moving beyond older, less efficient methods like cell-based access control or overlay networks.
Classification
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (197 CRs across 5 releases). Complements the general historical overview above with the evidence-based evolution of this function.
In Release 15, the 3GPP specifications newly introduced the Local Area Data Network (LADN) function, defining it as a data network accessible by the UE only in specific locations for a specific DNN. The release specified procedures for LADN configuration of the UE, how the AMF provides LADN information to the UE, and how the SMF validates UE location for LADN PDU Session establishment. It also introduced specific 5GSM causes, such as cause #46 for when a UE is out of the LADN service area, and clarified UE behavior including LADN indication during registration.
- SM cause for out of LADN service area TS 24.501CR0060
- LADN indication from UE at registration TS 24.501CR0065
- Clarification on 5GSM cause_#46 out of LADN service area TS 24.501CR0598
- Clarification in LADN clause 5.6.5 - TS 23.501 TS 23.501CR0022
- Complete of IMS Emergency support in 5G including slice and local numbers TS 23.501CR0052
- Clarification on location reporting for LADN in RRC Inactive clause 5.3.3.2.5 - TS 23.501 TS 23.501CR0136
+ 39 more changes
In Release 16, the LADN function was enhanced with clarifications and extended support for various scenarios. This included handling in ETSUN scenarios, support for Multi-Access PDU Sessions, and procedures for transferring a PDU session for LADN to EPS. The release also introduced refinements like routing policies based on local routing indications and clarified UE behavior when operating outside a LADN service area.
- Transfer of N4 information for local traffic switching from SMF to I-SMF TS 23.501CR1050
- LADN handling in ETSUN scenario TS 23.501CR1177
- Extending the significance of the locality parameter TS 23.501CR1312
- Missing "UE presence in LADN service area" attribute TS 29.502CR0174
- Local cache information for ARP proxy TS 23.501CR1116
- Clarification of the Locality of a NF Instance TS 23.501CR1470
+ 16 more changes
In Release 17, the LADN function was enhanced with extended UE Mobility Analytics to support LADN DNN and the introduction of overlapping LADN service areas. It also included clarifications on LADN information updates and specific procedures for the local release of PDU sessions due to Service Area Restriction. Furthermore, enhancements were made to the N4 interface for local notification and to support local deactivation of UP resources.
- Adding the usage of extended UE Mobility analytics for LADN service TS 23.501CR2582
- Adding some parameters for local NEF selection TS 23.501CR2656
- Newly added parameters for Local NEF discovery TS 23.501CR2856
- N4 interface enhancement for local notification TS 23.501CR2899
- 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
+ 23 more changes
In Release 18, the LADN function was enhanced to support access to localized services via Standalone Non-Public Networks (SNPNs), including procedures for UE discovery, selection, and network access control for these hosting networks. Key updates included the provisioning of service areas for enhanced group management and specific clarifications for onboarding within SNPNs supporting localized services. Furthermore, the release introduced support for LADN configurations per Data Network Name (DNN) and S-NSSAI, with corresponding updates to 5G Mobility Management (5GMM) and Session Management (5GSM) procedures.
- Support of local switch via UPF deployed on satellite for GEO backhaul case TS 23.501CR3794
- Introduction to Localized Services TS 23.501CR3842
- Enabling Access to Localized Services TS 23.501CR3992
- Support for leaving network that provides access to localized services TS 23.501CR3843
- UE discover, select and access to a Hosting network for Localized services TS 23.501CR3883
- Service area provisioning and LADN aspects for enhanced group management TS 23.501CR3914
+ 69 more changes
In Release 19, the enhancements for Local Area Data Network (LADN) functionality focused on the management of local offloading via an Intermediate SMF (I-SMF). Key additions included procedures for I-SMF selection and insertion based on a local offloading allowed indication, along with corresponding handling and policy provisioning at the I-SMF. The release also specified enhancements to control plane interfaces like N11, N16a, and N38 to support this I-SMF based Local Offloading Management architecture.
- Local Offloading Policy provisioning TS 23.501CR5463
- I-SMF selection/insertion based on local offloading allowed indication TS 23.501CR5604
- Local Offloading handling at I-SMF TS 23.501CR5744
- KI#1 Architecture for Local Offloading Management TS 23.501CR5752
- Local Offloading handling at I-SMF TS 23.501CR5825
- PCF's awareness of I-SMF insertion for Local Offloading Management TS 23.501CR5833
+ 20 more changes
Explore further
Broader topics and technologies where LADN plays a role.
Defining Specifications
3GPP specifications that define or reference LADN, with the latest known release. Sourced from the 3GPP document catalog — see methodology.
| Specification | Title | Release |
|---|---|---|
| TS 23.501 vk00 | 5G System Architecture Stage 2 | Rel-20 |
| TS 23.558 vk00 | Architecture for Edge Applications | Rel-20 |
| TR 23.758 vh00 | Study on Edge Application Architecture | Rel-17 |
| TS 24.193 vj50 | ATSSS Procedures Specification | Rel-19 |
| TS 24.501 vj50 | 5G NAS Protocols Specification | Rel-19 |
| TS 24.526 vj30 | UE Policies for 5GS; Stage 3 | Rel-19 |
| TS 24.890 vg00 | 5G NAS Protocol for 5GS Stage 3 | Rel-16 |
| TR 26.803 vh00 | 5G Media Streaming Extensions for Edge Processing | Rel-17 |
| TS 26.891 vg00 | Media Distribution Services in 5G System | Rel-16 |
| TS 29.502 vj50 | 5G System; Nsmf Service Based Interface; Stage 3 | Rel-19 |
| TS 29.518 vj50 | AMF Service Based Interface Protocol | Rel-19 |
| TS 29.520 vj40 | 5G Network Data Analytics Services Stage 3 | Rel-19 |
| TS 29.558 vj40 | Enabling Edge Applications | Rel-19 |
| TR 33.839 vh10 | Edge Computing Security Study for 5G Core | Rel-17 |