Description
Packet Set Error Rate (PSER) is a statistical QoS metric defined within the 5G Quality of Service (QoS) framework. It quantifies the reliability of packet delivery for applications where data is organized into logical groups or 'packet sets'. A packet set is a collection of packets that are semantically related and have a collective delivery deadline. The PSER is calculated as the ratio of packet sets that experience at least one packet delivery failure (e.g., loss, excessive delay beyond a latency bound, or out-of-order delivery that violates application constraints) to the total number of packet sets transmitted.
The metric operates in conjunction with other QoS parameters like Packet Delay Budget (PDB) and Packet Error Rate (PER). However, PSER provides a more holistic view for applications where the integrity of an entire data unit (the set) is paramount. The network uses the PSER target, along with the associated latency bound (often a maximum allowed packet delay), to make resource allocation and scheduling decisions. For instance, for an Augmented Reality stream, a frame might be composed of multiple packets; the PSER ensures the entire frame is delivered correctly and on time, as the loss of even one packet could degrade the user experience.
Architecturally, PSER is part of the 5G QoS Indicator (5QI) table and associated QoS Flow descriptions. It is signaled between the User Equipment (UE), the Radio Access Network (RAN), and the Core Network (specifically the Session Management Function - SMF) to establish the required service characteristics. The RAN scheduler is a key component responsible for meeting the PSER target, employing techniques like prioritized scheduling, redundancy (e.g., through packet duplication), or hybrid automatic repeat request (HARQ) strategies tailored for set-based reliability.
PSER's role is pivotal for enabling deterministic communication in 5G-Advanced and beyond. It moves beyond per-packet guarantees to per-data-unit guarantees, which is essential for time-sensitive applications. Its specification across documents like TS 23.501 (system architecture), TS 38.300 (RAN overall), and TS 38.835 (work on NR industrial IoT) highlights its integration into both the core service definition and the radio interface procedures.
Purpose & Motivation
PSER was created to address the stringent and complex reliability requirements of emerging 5G-Advanced and 6G-era applications, particularly extended reality (XR), cloud gaming, and ultra-reliable low-latency communication (URLLC) for industrial automation. Traditional QoS metrics like Packet Error Rate (PER) and Packet Delay Budget (PDB) provide guarantees on individual packets but do not adequately capture the performance needs of applications where data is structured in groups (e.g., a video frame, a control command with multiple parameters, or a synchronized sensor burst). A single packet loss within such a group could render the entire data unit useless, even if the average PER is low.
The motivation stems from the limitations of previous approaches. Guaranteeing a low PER for every packet is often inefficient and resource-intensive. PSER allows the network to optimize resource usage by focusing on the successful delivery of logically complete sets within a time window, providing a more application-aware reliability metric. This enables network slicing and QoS frameworks to support services with 'bounded reliability' – a concept where occasional set failures might be tolerable if bounded within a statistical limit, allowing for more flexible and efficient network operation compared to traditional 'five-nines' (99.999%) per-packet reliability models that are often over-provisioned.
Historically, as 3GPP evolved from enhanced Mobile Broadband (eMBB) to massive IoT and critical IoT, the need for more granular and diverse QoS metrics became apparent. PSER, introduced in Release 18 as part of the work on enhanced XR and industrial IoT, represents a significant step in refining the QoS toolbox. It allows service providers to define and guarantee Service Level Agreements (SLAs) that directly map to the perceptual or operational quality of the end-user application, facilitating new revenue streams and enabling truly deterministic wireless performance for industry 4.0.
Classification
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (81 CRs across 5 releases). Complements the general historical overview above with the evidence-based evolution of this function.
In Release 15, the specification for the Packet Set Error Rate (PSER) function was introduced to support Ultra-Reliable Low Latency Communication (URLLC) services by defining key 5G QoS attributes, including Packet Delay Budget (PDB) and Packet Error Rate (PER), which ensure bounds on latency and reliability for a QoS Flow. This enhancement is part of broader QoS fixes for URLLC, integrating these parameters into the 5QI framework to facilitate stringent packet transport requirements. The release also clarified related packet handling mechanisms, such as the use of packet filters and traffic mapping information to manage uplink and downlink packet routing within the 5G system.
- PS Data Off supporting non-IP data packet TS 23.501CR0680
- Corrections to RQoS logic when receiving DL packet with RQI TS 23.501CR0011
- Proposal of Specifying Packet Detection Rule TS 23.501CR0027
- Corrections and clarifications for the usage of Packet Filter Set TS 23.501CR0035
- Traffic mapping information that disallows UL packets TS 23.501CR0053
- 5G QoS fixes for URLLC services related attributes - PDB, PER, MDB, 5QI TS 23.501CR0087
+ 8 more changes
In Release 16, the PSER function was enhanced to support Ultra-Reliable Low Latency Communications (URLLC), including the introduction of QoS monitoring for packet delay and loss, and the handling of redundant PDU sessions for URLLC traffic. It also added mechanisms for UPF selection specific to URLLC PDU sessions and clarified procedures for GTP-U path monitoring and packet delay calculation to support these stringent reliability requirements. Furthermore, the release specified the forwarding of broadcast/multicast packets and introduced N4 notifications for dropped buffered packets to improve reliability assurance.
- New clause for URLLC supporting TS 23.501CR0810
- Introduction of QoS Monitoring to assist URLLC Service TS 23.501CR0990
- Description of URLLC features in NF description clauses TS 29.514CR0249
- 5G URLLC: Optimizing Redundancy TS 23.501CR1217
- Clarifications on URLLC support TS 23.501CR1643
- Support of forwarding of broadcast and multicast packets TS 23.501CR1659
+ 17 more changes
In Release 17, the PSER function was enhanced to support Ultra-Reliable Low Latency Communication (URLLC) services, including the introduction of redundant transmission experience analytics. This release also defined new measurements for Packet Loss Rate and refined the reporting of application errors and AF-influenced traffic routing events to improve reliability monitoring.
- Adding the usage of Redundant Transmission Experience analytics for URLLC service TS 23.501CR2581
- Packet Loss Rate measurements TS 23.501CR2587
- Application error. TS 29.514CR0315
- AF influence on traffic routing related events and errors report. TS 29.514CR0325
- Resolves the editor’s note for FILTER_RESTRICTIONS application error TS 29.514CR0355
- Introduction of Rel-17 IIoT/URLLC to TS 38.300 TS 38.300CR0416
+ 8 more changes
In Release 18, the PSER (Packet Set Error Rate) function was introduced as a new QoS monitoring parameter, superseding the previous PER (Packet Error Rate) and PDB (Packet Delay Budget) metrics per direction. This enhancement, alongside the support for Packet Delay Variation monitoring, provides more granular bounds on latency, loss, and reliability for QoS flows. The changes are part of broader URLLC enhancements aimed at ensuring packet transport with stricter QoS characteristics.
- PCF support of 5GS Packet Delay Variation monitoring based on QoS monitoring mechanism and exposed to AF TS 23.501CR3792
- Update about the Packet Delay Variation description and add PDV in QoS monitoring parameters TS 23.501CR4506
- Support of Packet Delay Variation monitoring and reporting TS 29.514CR0519
- Support of the Packet Delay Variation monitoring TS 29.514CR0541
- Introduction of Timing Resiliency and URLLC enhancements TS 38.300CR0730
- Relaxation of 5QI delay requirements for first packets should also apply for RRC-INACTIVE mode. TS 23.501CR4709
+ 16 more changes
In Release 19, the PSER (Packet Set Error Rate) function received clarification specifically regarding its application within the alternative QoS framework. This was detailed alongside the PSDB (Packet Set Delay Budget) to refine the bounds on latency, loss, and reliability characteristics for packet transport. The enhancements contribute to ensuring isochronous communication with high reliability and availability as part of the 5G QoS model.
- Adding the NAT information exposure and Packet Inspection functionality in the UPF NF profile TS 23.501CR5420
- Clarification on the PSDB and PSER in the alternative QoS TS 29.514CR0772
- Complete error handling for the AF requested multiplexed media flows TS 29.514CR0792
- KI#4: Correct the RTCP 'MID' for IP packet filter set TS 23.501CR5958
- Clarification on VLAN tag error TS 23.501CR6449
- Transport level packet marking considering PSI TS 23.501CR6478
+ 2 more changes
Explore further
Broader topics and technologies where PSER plays a role.
Defining Specifications
3GPP specifications that define or reference PSER, 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 23.700 vk00 | XR Services Application Enablement Layer | 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 |