Description
Product Specific Applications (PSA) is a term used across numerous 3GPP specifications to denote application functions or services that are not generic but are tied to a specific commercial product, service bundle, or use case. It is not a single protocol or network function but a conceptual entity used in requirement and architectural modeling. PSAs represent the logical endpoint or source of service-specific traffic and signaling that the 5G System (5GS) must support. They are often discussed in the context of service-based architecture, network exposure, and quality of service (QoS) differentiation.
Architecturally, a PSA interacts with the 5G Core Network (5GC) through defined interfaces, primarily the Network Exposure Function (NEF) or directly with the User Plane Function (UPF) for traffic steering. The PSA can be an Application Function (AF) as defined in the 5GC architecture, but with the distinguishing characteristic of being product-specific. This means its communication with the network carries requirements unique to the product it enables, such as specific QoS parameters (e.g., latency, reliability), charging policies, or mobility restrictions. The 5GC uses the information provided by or about the PSA to apply appropriate network policies.
How it works involves the PSA (or an entity representing it, like an AF) providing session or service-related information to the 5GC. For example, a PSA for a real-time gaming service might request a guaranteed bit rate and low-latency QoS flow for its users via the NEF. The Policy Control Function (PCF) would then generate policies based on this request and the user's subscription, and the Session Management Function (SMF) would enforce them by configuring the UPF accordingly. The role of the PSA concept is to provide a formal model for these product-specific interactions, ensuring the network can be dynamically tailored to support a vast array of specialized services beyond basic connectivity, which is central to the 5G vision of network-as-a-service.
Purpose & Motivation
The concept of Product Specific Applications exists to address the need for the 3GPP system to support a diverse and ever-growing ecosystem of specialized services, each with unique network requirements. In early mobile networks, services were largely monolithic (e.g., voice, SMS, basic internet). As networks evolved, operators and third parties began offering differentiated products like streaming bundles, IoT solutions, and enterprise VPNs, which required the network to treat their traffic differently.
PSA provides a standardized way to model these bespoke services within the 3GPP architecture. It solves the problem of how to formally describe and integrate the requirements of a specific commercial product into the network's control and management planes. Before such modeling, enabling a new service often required proprietary integrations or broad, inefficient network configurations. The PSA concept, particularly as refined in the 5G service-based architecture, allows for dynamic, policy-driven network slicing and QoS management on a per-application or per-product basis. This enables operators to efficiently monetize their networks by offering tailored connectivity as a product feature.
Release Timeline
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (14 CRs across 4 releases). Complements the general historical overview above with the evidence-based evolution of this function.
In Release 16, the PSA function was enhanced to support a "Local PSA" (L-PSA) deployed on a satellite, operating in conjunction with an Uplink Classifier or Branching Point (UL CL/BP) to route user plane traffic locally, such as for IMS or 5G LAN services. This enables UE-to-UE communication via the satellite and introduces procedures for the SMF to dynamically decide, based on local configuration, whether to route traffic to a ground-based PSA or retain the UL CL/L-PSA on the satellite during events like a serving satellite change. The release also specifies mechanisms for the simultaneous change or removal of the UL CL/BP and L-PSA, including the management of N9 and N19 forwarding tunnels between PSA UPFs.
- UL FAR in UL CL or BP towards Local PSA TS 29.244CR0297
In Release 17, enhancements for the PSA function introduced an AF Request for Simultaneous Connectivity over Source and Target PSA during Edge Relocation, allowing both PSA UPFs to coexist temporarily via an N9 forwarding tunnel. Furthermore, the specifications now support a simultaneous change of the Branching Point or UL CL and an additional PSA, enabling the SMF to allocate a new UL CL/BP and local PSA on a target satellite during UE mobility. These additions provide greater flexibility for session continuity, particularly in satellite and edge computing scenarios.
- EC KI2 Target PSA buffering TS 23.501CR2646
- Outer Header Removal for PSA UPF TS 29.244CR0644
- AF Request for Simultaneous Connectivity over Source and Target PSA at Edge Relocation TS 29.512CR0872
- AF Request for Simultaneous Connectivity over Source and Target PSA at Edge Relocation TS 29.513CR0316
- AF Request for Simultaneous Connectivity over Source and Target PSA at Edge Relocation TS 29.514CR0368
- AF Request for Simultaneous Connectivity over Source and Target PSA at Edge Relocation TS 29.519CR0291
+ 2 more changes
In Release 18, enhancements were made to the PSA (PDU Session Anchor) function, specifically introducing new procedures for PSA UPF selection and clarifying the use of the N19 interface. The release provides detailed mechanisms for the SMF to decide between routing traffic to a ground-based PSA or retaining a local PSA on a satellite, particularly for IMS services and UE-satellite-UE communication. It also defines the conditions for maintaining or removing N9/N19 forwarding tunnels during PSA relocation, influenced by application function requests and policies for IP address preservation.
In Release 19, enhancements for the PSA function introduced support for UPF selection based on N6 delay measurements and refined procedures for PSA re-selection and edge relocation. The release also removed the restriction on simultaneous PSA connectivity, allowing for coexistence of source and target PSAs during relocation, which influences the establishment of temporary N9 forwarding tunnels. Furthermore, mechanisms were aligned for scenarios involving L-PSA UPFs onboard satellites, detailing SMF decisions on routing IMS traffic and procedures for maintaining or removing UL CL/L-PSA during satellite changes.
Explore further
Broader topics and technologies where PSA plays a role.
Defining Specifications
3GPP specifications that define or reference PSA, 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 23.527 vj50 | 5G System Restoration Procedures | Rel-19 |
| TS 23.558 vk00 | Architecture for Edge Applications | Rel-20 |
| TS 23.700 vk00 | XR Services Application Enablement Layer | Rel-20 |
| TR 23.794 vh00 | Study on enhanced IMS to 5GC integration | Rel-17 |
| TR 26.803 vh00 | 5G Media Streaming Extensions for Edge Processing | Rel-17 |
| TS 26.804 vj10 | 5G Media Streaming Extensions Study | Rel-19 |
| TR 26.806 vi00 | Technical Report on Smartly Tethering AR Glasses | Rel-18 |
| TR 28.822 vh00 | Charging for 5G LAN Services Study | Rel-17 |
| TR 28.833 vi01 | Technical Report on 5G LAN-type Service Management | Rel-18 |
| TS 29.244 vj40 | PFCP Specification for Control/User Plane Separation | Rel-19 |
| TS 29.512 vj40 | 5G Session Management Policy Control Service | Rel-19 |
| TS 29.513 vj40 | 5G PCC Signalling Flows & QoS Mapping | Rel-19 |
| TS 29.514 vj40 | 5G System; Policy Authorization Service; Stage 3 | Rel-19 |
| TS 29.519 vj40 | UDR Usage for Policy & Exposure Data | Rel-19 |
| TS 29.892 vg00 | Study on User Plane Protocol in 5GC | Rel-16 |
| TS 32.102 vj00 | Telecom Management Physical Architecture Framework | Rel-19 |
| TS 32.150 vj00 | IRP Concept and Definitions | Rel-19 |
| TR 33.739 vi10 | Study on security enhancement of support for | Rel-18 |
