Description
The UE Policy Section Identifier (UPSI) is a critical component within the 3GPP's Policy Control Framework, specifically defined for the 5G System (5GS). It functions as a unique label or key that identifies a discrete, self-contained block of policy rules—known as a UE Policy Section—that is provisioned to the User Equipment (UE) by the network's Policy Control Function (PCF). The UE Policy itself is a comprehensive document that can contain multiple such sections, each identified by its own UPSI. These sections can pertain to different policy domains, such as Access Network Discovery and Selection Policy (ANDSP) for selecting between 3GPP and non-3GPP access, or UE Route Selection Policy (URSP) for determining how application traffic is routed (e.g., to a specific Data Network Name (DNN) or Network Slice). The UE stores these policy sections locally, associating each with its UPSI.
Architecturally, the UPSI is generated and managed by the PCF. When the PCF determines that a UE requires a new or updated policy, it assembles the UE Policy container, which includes one or more UE Policy Sections, each tagged with a UPSI. This container is then delivered to the UE via the Access and Mobility Management Function (AMF) using the N1 NAS transport mechanism. The specification 24.501 details the NAS signaling procedures for this delivery. The PCF can also manage the lifecycle of these policy sections through the Npcf_UEPolicyControl service, defined in 29.525, allowing it to provision, update, or delete specific sections identified by their UPSI.
The role of the UPSI is to enable efficient and granular policy management. Instead of retransmitting the entire UE Policy document for every change, the network can target individual sections. The UE uses the UPSI to identify which stored policy section to apply for a given context. For instance, when the UE needs to select an access network, it will locate the ANDSP section using its specific UPSI. This modular approach reduces signaling overhead, conserves UE storage by allowing selective updates, and provides the network with fine-grained control over UE behavior. The management of these identifiers and their associated sections is further supported by services like the Network Repository Function (NRF) for discovery, as referenced in specs 29.513 and 29.519.
Purpose & Motivation
The UPSI was introduced in 5G (Release 15) to address the limitations of monolithic policy management in previous generations like 4G EPS. In EPS, policy information like ANDSP was delivered as a single, indivisible blob. Any change, no matter how small, required the entire policy to be re-sent, leading to inefficient use of radio resources and UE processing. As 5G introduced more complex policy domains (notably URSP for sophisticated traffic steering and network slice selection), the need for modular, granular policy control became paramount.
The creation of the UPSI enables a data-driven, service-based policy architecture aligned with 5G's core principles. It solves the problem of scalable policy distribution in a network supporting diverse use cases, from enhanced mobile broadband to massive IoT and ultra-reliable low-latency communications. Each use case or tenant (via network slicing) might require a distinct set of rules. The UPSI allows the PCF to compose a tailored policy from discrete, reusable sections, updating only the parts that change. This is essential for supporting dynamic network conditions, subscriber-specific services, and efficient UE resource management, forming a foundational element for automated network and service management.
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (269 CRs across 5 releases). Complements the general historical overview above with the evidence-based evolution of this function.
In Release 15, the UE Policy Section Identifier (UPSI) function was introduced as part of the new UE policy delivery service between the UE and the Policy Control Function (PCF). This release specified the procedures for UE policy delivery over both 3GPP and non-3GPP access, including the UE-initiated NAS transport procedure for sending a UE policy container. Furthermore, it defined the management of UE policy sections for multiple PLMNs and established procedures for UE policy association.
- AM policy data resource definition TS 29.519CR0010
- SM policy data resource definition TS 29.519CR0011
- Policy data change subcription TS 29.519CR0015
- Resource Structure for policy data TS 29.519CR0026
- Introduce the operator policy data TS 29.519CR0038
- No operation code for UE policy management TS 24.501CR0112
+ 37 more changes
In Release 16, the UPSI function was extended to support a UE-requested V2X policy provisioning procedure, allowing the UE to initiate policy updates via an UL NAS TRANSPORT message containing a UE policy container. This release also introduced specific handling for Vehicle-to-Everything (V2X) policy, including procedures for N2 PC5 Policy and corrections to the overall V2X policy provisioning mechanism. Furthermore, enhancements were made to enable subscription and notification for changes to specific subsets of policy data within the repository.
- USPS extension for V2X policy TS 24.501CR1281
- UPDS updates enabling UE-requested V2X policy provisioning procedure TS 24.501CR1692
- Retrieval of BDT policy data for a set of BDT reference identifiers TS 29.513CR0086
- Subscription to Notification of change of PLMN Identifier at initial IMS Registration TS 29.513CR0133
- Procedure of N2 PC5 Policy TS 29.513CR0179
- Retrieval of BDT policy data for a set of BDT reference identifiers TS 29.519CR0144
+ 38 more changes
In Release 17, the UPSI function was enhanced to support UE policy updates for Application Function (AF) influence on URSP and to enable policy decisions based on Network Analytics. The release also introduced support for binding principles for UE Policy Delivery outcomes and expanded policy data handling, including extensions for UE-Slice-MBR and support for MBS policy control. Furthermore, procedures like the AM Policy Authorization and association were updated to support DCAMP, and enhancements were made for the retrieval of multiple policy data sets.
- General section for ID_UAS TS 24.501CR3135
- ProSe policy provisioning start and stop indications TS 24.501CR3127
- UE ProSe policy transmission TS 24.501CR3110
- AM Policy Authorization procedure for DCAMP TS 29.513CR0274
- AM Policy association procedure updates to support DCAMP TS 29.513CR0275
- Handling of Session Management Policy Data per PLMN TS 29.513CR0294
+ 62 more changes
In Release 18, the UPSI function was expanded to support new policy sections for A2X (Automotive-to-Everything) service parameters and Ranging/Sidelink Positioning (RSLPP), and to enable UE policy association procedures for both 3GPP and non-3GPP accesses. It also introduced updates for policy control inputs and delivery procedures related to ANDSP (Access Network Discovery and Selection Policy) determination. Furthermore, the release added support for spending limits applied to UE policy and enhanced procedures for PDTQ (Policy Data Transfer QoS) policy negotiation.
- Transmission of A2X Policy TS 24.501CR5050
- Transmission of Ranging/SL Positioning Policy TS 24.501CR5197
- General section for MBSR TS 24.501CR5220
- Indicating the support of URSP rule enforcement in the UE policy classmark TS 24.501CR5339
- Clarification about the condition of the PCF initiating the Network-requested UE policy management procedure TS 24.501CR5430
- Updation of general section for unavailability period TS 24.501CR5616
+ 73 more changes
In Release 19, the UPSI function was enhanced to enable the storage of UE Policy Section Identifiers for a wider set of pre-configured policy rules and node information. Specifically, new support was added for the storage of UPSI(s) associated with stored signalled URSP rules, as well as for the configuration information of ProSeP, V2XP, A2XP, RSLPP, and N3AN nodes within the ANDSP policy.
- Support of reject QoS differentiation for non-3GPP device identifier(s) TS 24.501CR6926
- Procedure update for QoS differentiation of non-3GPP device identifiers TS 24.501CR6994
- Support of the minimize number for the UE Policy TS 29.513CR0561
- UE and AM Policy Association control based on UDM Subscription Data TS 29.513CR0562
- Introduction of QoS and Policy Assistance analytics TS 29.513CR0600
- Support of satellite identifier report at call set-up TS 29.513CR0602
+ 29 more changes
Explore further
Broader topics and technologies where UPSI plays a role.
Defining Specifications
3GPP specifications that define or reference UPSI, with the latest known release. Sourced from the 3GPP document catalog — see methodology.
| Specification | Title | Release |
|---|---|---|
| TS 24.501 vj50 | 5G NAS Protocols Specification | Rel-19 |
| TS 29.513 vj40 | 5G PCC Signalling Flows & QoS Mapping | Rel-19 |
| TS 29.519 vj40 | UDR Usage for Policy & Exposure Data | Rel-19 |
| TS 29.525 vj40 | 5G UE Policy Control Service Stage 3 | Rel-19 |