Description
PDU Set Integrated Handling Information (PSIHI) is a protocol feature introduced in 3GPP Release 18 as part of 5G-Advanced enhancements, designed to improve the handling of data units in the user plane. It refers to control information that is integrated with a set of Protocol Data Units (PDUs) to provide instructions on how these PDUs should be processed, transmitted, or managed collectively by the network and User Equipment (UE). PSIHI is carried within the data flow, typically in packet headers or associated metadata, and conveys semantics related to the application data, such as dependencies between PDUs, processing deadlines, or aggregation rules. This allows the 5G system to apply optimized handling strategies—like scheduling, duplication, or discard—based on the application's needs, rather than treating each PDU independently.
Architecturally, PSIHI operates within the Packet Data Convergence Protocol (PDCP) layer and potentially interacts with higher layers like the Service Data Adaptation Protocol (SDAP) and application layer in the 5G protocol stack. It is generated by the application or a network function (e.g., an edge server) and embedded into the PDU set before transmission over the air interface. The gNodeB (gNB) and UE use this information to make intelligent decisions in the radio access network (RAN) and core network. For instance, PSIHI might indicate that a group of PDUs belongs to a single video frame, allowing the RAN to prioritize or discard them as a unit to maintain quality of service. Key components include the PSIHI field itself, which contains flags or parameters defining the handling rules, and the associated protocols that parse and act on this information, as specified in technical specifications like TS 38.300 and TS 38.835.
In practice, PSIHI enhances user plane efficiency by enabling context-aware data handling. When a PDU set with PSIHI arrives at the gNB, the scheduler can consider the integrated information to optimize resource allocation—for example, by ensuring that all PDUs in a set are transmitted contiguously to reduce latency for time-sensitive applications. On the UE side, the receiver uses PSIHI to reassemble or process PDUs correctly, potentially reducing buffer requirements and improving application performance. This mechanism is particularly valuable for advanced use cases like extended reality (XR), industrial IoT, and ultra-reliable low-latency communication (URLLC), where data semantics are critical for meeting stringent requirements. By bridging the gap between application intent and network behavior, PSIHI supports more dynamic and efficient 5G systems.
Purpose & Motivation
PSIHI was created to address the limitations of traditional PDU handling in 5G networks, where each data unit is processed independently without awareness of application-level context. Previous approaches, while efficient for generic data traffic, struggled to meet the complex requirements of emerging applications like XR, autonomous systems, and tactile internet, which involve structured data sets with interdependencies and strict timing constraints. Without integrated handling information, the network might inadvertently discard or delay critical PDUs, degrading user experience and reliability.
The primary problem PSIHI solves is the inefficiency in resource utilization and quality of service management for application-aware services. By providing explicit handling instructions within the data flow, it enables the RAN and core network to optimize transmission strategies based on semantic knowledge. This reduces overhead compared to out-of-band signaling and allows for real-time adaptations, such as grouping PDUs for joint scheduling or applying specific error recovery mechanisms. The motivation for PSIHI stems from the 5G-Advanced vision of supporting more intelligent and flexible networks, where user plane enhancements are key to achieving higher performance and energy efficiency.
Historically, earlier 3GPP releases relied on QoS flows and differentiated services code points (DSCP) for traffic differentiation, but these mechanisms lacked granularity for PDU-level coordination within a flow. PSIHI builds on concepts like PDCP duplication and data burst handling, extending them with integrated control to support the evolving needs of vertical industries. Its introduction in Release 18 was driven by industry demands for better support of XR and industrial applications, as documented in specs like TS 26.804 and TS 23.501, where handling of media frames and sensor data sets requires tight integration between application and network layers.
Classification
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (411 CRs across 6 releases). Complements the general historical overview above with the evidence-based evolution of this function.
In Release 15, the PSIHI (PDU Set Integrated Handling Information) function was newly introduced to manage the integrated handling of PDU Sets, which are one or more PDUs carrying application-level payload, within the User Plane Information Exposure architecture. This enables the UPF to expose event notifications containing this information to authorized network functions like the NWDAF, NEF, and SMF via a service-based interface. The introduction supports enhanced traffic detection and routing using Network Instance information and aligns with the handling of application data such as Packet Flow Descriptions (PFDs).
- CR on U-plane handling for handover TS 38.300CR0029
- Configuration information the UE may exchange with the SMF during the lifetime of a PDU Session TS 23.501CR0003
- Handling of MM back-off timer for N3GPP Access TS 23.501CR0004
- Correction to handling of S-NSSAI mapping information TS 23.501CR0020
- Update on Traffic Detection Information TS 23.501CR0026
- Traffic mapping information that disallows UL packets TS 23.501CR0053
+ 45 more changes
In Release 16, the PSIHI function was enhanced to support the exposure of user plane information via a service-based interface from the UPF to authorized network functions like the NWDAF, NEF, and SMF. This introduced new capabilities for UPF event notifications, enabling the transfer of specific information such as access network charging correlation and access network information. Additionally, the handling of PDU sets was extended to support new scenarios including local traffic switching via N4 information transfer and the handling of stored small data rate control status.
- Description of solution 2 in 23.725 for redundancy as an informational annex TS 23.501CR0754
- Location information TS 23.501CR0941
- Transfer of N4 information for local traffic switching from SMF to I-SMF TS 23.501CR1050
- Support of emergency services in public network integrated NPNs TS 23.501CR1073
- LADN handling in ETSUN scenario TS 23.501CR1177
- Adding NF load information inside NFprofile TS 23.501CR1187
+ 104 more changes
In Release 17, the enhancements for the PDU Set Integrated Handling Information (PSIHI) function included new support for exposing User Plane information via a service-based interface from the UPF to authorized network functions like the NWDAF and NEF. This release also introduced specific handling for Ethernet PDU Session types within Multi-Access PDU Sessions and clarified the transport of management information, such as PMF data, over the N4 interface.
- Service Assistance Information for 3GPP Advanced Interactive Service TS 23.501CR2653
- UPF function update to support network information exposure TS 23.501CR2900
- L2TP information provision TS 23.501CR2973
- AUSF/UDM discovery based SUCI information TS 23.501CR3170
- Authentication and Subscription information checking for Disaster Roaming service TS 23.501CR3251
- Adding EAS IP replacement information in Policy Authorization TS 29.514CR0356
+ 50 more changes
In Release 18, the PSIHI (PDU Set Integrated Handling Information) function was enhanced to support PDU Set based handling and QoS handling for uplink transmission, including support for non-homogenous QoS within a PDU Set. These capabilities were integrated into the 5G system architecture, with updates to the Npcf_PolicyAuthorization service and the exposure of related management information via the NEF to support temporal validity conditions for groups of UEs.
- Introduction of 5GS Information Exposure TS 23.501CR3887
- KI#3, NEF exposure for handling PDU Session Type change and managing temporal invalidity/validity condition for a group of UEs TS 23.501CR3964
- Support of PDU Set based handling TS 23.501CR4046
- SNPN broadcast system information and manual network selection for localized service TS 23.501CR4095
- Delivery of Traffic Influence information for Home Routed-Session Breakout (HR-SBO) support TS 23.501CR4160
- Extension of NWDAF registration information to reflect new accuracy checking capability TS 23.501CR3764
+ 82 more changes
In Release 19, the PSIHI function was enhanced to support the identification of PDU Sets for end-to-end encrypted traffic using connect-UDP and based on MoQ for encrypted XRM traffic. Furthermore, it introduced the capability to leverage PDU Set QoS information for differentiated handling and DSCP marking over N3/N9 transport interfaces. These additions enable more granular quality of service and routing for encrypted, multiplexed media flows within the 5G system architecture.
- Adding the NAT information exposure and Packet Inspection functionality in the UPF NF profile TS 23.501CR5420
- Introduction of new network function for energy related information, its definition and corresponding Architecture Reference Model TS 23.501CR5636
- Support of Handling of Headers TS 23.501CR5454
- General description of relaying media related information over N6 using an encapsulation protocol TS 23.501CR5711
- Support PDU Set information identification based on MoQ for encrypted XRM traffic TS 23.501CR5632
- PDU Set Information Identification for end-to-end encrypted traffic using connect-UDP - architecture part TS 23.501CR5728
+ 96 more changes
In Release 20, the PSIHI function was enhanced by introducing the Energy Information Function (EIF) to expose energy consumption information and policy control, and by correcting mistakes related to PDU Set based handling and QoS handling. The architecture now includes a direct service-based interface for the EIF to request energy-related information from OAM, as defined in TS 28.622. Furthermore, the release clarified that a Data Burst can be composed of one or multiple PDU Sets, which carry the payload of one unit of application-level information.
- N3IWF/TNGF reselection considering energy related information. TS 23.501CR6493
- KI#1: Per UE application ranking related information exposed by EIF TS 23.501CR6501
- Energy Consumption information exposure and policy control TS 23.501CR6508
- Fix the mistake of PDU Set based handling and PDU Set based QoS handling TS 23.501CR6526
Explore further
Broader topics and technologies where PSIHI plays a role.
Defining Specifications
3GPP specifications that define or reference PSIHI, 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 26.804 vj10 | 5G Media Streaming Extensions Study | Rel-19 |
| TS 29.514 vj40 | 5G System; Policy Authorization Service; Stage 3 | Rel-19 |
| TS 38.300 vj00 | NG-RAN Overall Description | Rel-19 |
| TR 38.835 vi01 | Technical Report on XR Enhancements for NR | Rel-18 |