Description
Multi-Path QUIC (MPQUIC) is an extension of the QUIC transport protocol, standardized by the IETF and adopted by 3GPP. It allows a single QUIC connection to utilize multiple distinct network paths concurrently. This is achieved by establishing multiple subflows within a single connection, each bound to a different 5-tuple (source IP, source port, destination IP, destination port, transport protocol). Each subflow operates independently, with its own congestion control and packet numbering, but they share a common cryptographic and connection context. The protocol intelligently schedules packets across available paths based on real-time path characteristics like latency, loss, and available bandwidth. A key architectural component is the path manager, which discovers, validates, and monitors the viability of each potential path. MPQUIC also handles path migration seamlessly; if one path fails, traffic is immediately rerouted to other active paths without breaking the application-layer connection. This multi-path capability is integrated into the 5G system architecture, where it can leverage multiple PDU sessions, multiple access technologies (e.g., 3GPP and non-3GPP access), or different user plane functions. The 5G core network, through entities like the SMF and UPF, supports the establishment and policy control for connections that can exploit MPQUIC. From an endpoint perspective, devices with multiple radio interfaces (e.g., 5G NR and Wi-Fi) can use MPQUIC to bond these links, presenting a single, robust, high-performance pipe to the application layer.
Purpose & Motivation
MPQUIC was created to address the limitations of single-path transport protocols in increasingly heterogeneous and multi-connected network environments. Traditional TCP and even single-path QUIC are bound to one network path per connection, making them susceptible to the performance bottlenecks or failures of that single path. With the proliferation of devices equipped with multiple radios (e.g., 5G, LTE, Wi-Fi), there was a clear opportunity to improve performance, reliability, and user experience by utilizing all available links simultaneously. The primary problems MPQUIC solves are: 1) Inefficient resource utilization, where only one network interface is used at a time despite others being available; 2) Latency spikes and connection interruptions during handovers or path failures; and 3) Inability to aggregate bandwidth from disparate links to meet the high-throughput demands of modern applications like ultra-HD video, cloud gaming, and massive file transfers. Historically, solutions like MPTCP existed but faced deployment challenges due to middlebox interference and complex network integration. QUIC, being a UDP-based protocol encrypted by default, is more resilient to middlebox manipulation. Extending it with multi-path capabilities (MPQUIC) provided a cleaner, more deployable solution that aligns with the 5G architecture's native support for concurrent access and network slicing. Its adoption in 3GPP Rel-18 was motivated by the need for enhanced transport flexibility to support new service requirements for immersive media, industrial IoT, and reliable vehicular communications.
Classification
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (298 CRs across 6 releases). Complements the general historical overview above with the evidence-based evolution of this function.
In Release 15, foundational support for Multi-Path QUIC (MPQUIC) was introduced by enabling multi-homed IPv6 PDU Sessions, allowing a UE to utilize multiple network paths concurrently. This was complemented by the specification of procedures for access traffic splitting across these multiple accesses and the necessary routing rules for IPv6 multi-homing. Furthermore, the release defined architectural support for handling multiple PDU Sessions and the duplication of user plane packets to multiple destinations, which are key underlying capabilities for MPQUIC transport.
- UE support for Multi-homed IPv6 PDU Session TS 23.501CR0105
- Correction to Providing AF request to multiple PCFs TS 23.501CR0161
- Update for providing policy requirements to multiple UEs TS 23.501CR0280
- Avoid the case the one UE MAC shared by multiple Ethernet PDU Sessions TS 23.501CR0406
- IPv6 multi-homed routing rule TS 23.501CR0608
- Registration Area and Service Restriction Area in relation to multiple PLMNs TS 23.501CR0641
+ 12 more changes
In Release 16, the new MPQUIC function was introduced as part of the broader ATSSS (Access Traffic Steering, Switching and Splitting) framework, enabling a Multiple Access PDU Session. This release specifically defined procedures for the Multiple Access upgrade and modification of a PDU Session to support ATSSS parameters and steering functions, including QoS support and the derivation of ATSSS rules. Furthermore, it introduced the capability for performance measurements and usage monitoring control tailored for this multi-access environment.
- Introduction of ATSSS Support TS 23.501CR0735
- Support of Steering Functions for ATSSS TS 23.501CR0740
- QoS for Multi-Access PDU Session TS 23.501CR0770
- ATSSS-SMF and UPF selection TS 23.501CR0761
- Updating 5.8.2.11 for N4 Rules to support ATSSS TS 23.501CR0785
- Multiple Access PDU Session TS 24.501CR1122
+ 74 more changes
In Release 17, the new MPQUIC (Multi-Path QUIC) function was introduced, building upon the foundational QUIC transport protocol defined in IETF RFC 9000. The specification explicitly references the IETF draft for a Multipath Extension for QUIC, enabling the splitting of a service data flow's traffic across multiple access networks. This enhancement integrates with the existing Access Traffic Steering, Switching, and Splitting (ATSSS) framework to provide more robust and efficient multi-access data delivery.
- Multimedia Priority Service (MPS) Phase 2 support for Data Transport Service TS 23.501CR2536
- Applying thresholds to Load-Balancing steering mode in ATSSS TS 23.501CR2590
- Function Description for Multi-SIM devices TS 23.501CR2553
- Partial ATSSS rule update by using ATSSS rule ID TS 23.501CR2886
- Support multiple NSACFs for one S-NSSAI during UE mobility TS 23.501CR2909
- Definitions and abbreviations for Multi-USIM in 5GS TS 24.501CR3119
+ 42 more changes
In Release 18, the new MPQUIC (Multi-Path QUIC) functionality introduced a dedicated MPQUIC Steering Functionality and defined procedures for associating a QUIC connection with a QoS flow. The release specified how to determine the ATSSS capabilities of a Multi-Access PDU Session when the UE supports MPQUIC and resolved architectural exceptions for indicating this functionality on untrusted non-3GPP access. Furthermore, it defined a context identifier for transport mode 1 of the MPQUIC functionality and clarified that the redundant steering mode is not applicable for ATSSS-LL functionality.
- Multiple NSACF architecture enhancement TS 23.501CR3785
- KI#4: Support for Centralized NSACF in a PLMN with multi-service areas TS 23.501CR3822
- Policy control enhancements to support multi-modal flows TS 23.501CR3864
- Introduction of the MPQUIC Steering Functionality TS 23.501CR3973
- Support for 5G VN group with multiple SMF(Set)s TS 23.501CR4306
- Determining the ATSSS capabilities of a MA PDU Session when the UE supports MPQUIC TS 23.501CR4457
+ 65 more changes
In Release 19, the new MPQUIC (Multi-Path QUIC) function introduced specific support for MPQUIC-IP and MPQUIC-E steering functionalities, including handling of UE capability for these features. The release also added support for differentiated QoS handling for encrypted multiplexed media flows transported over MPQUIC. Furthermore, enhancements were made to support QoS for proxying IP and Ethernet traffic within HTTP sessions running over the MPQUIC transport protocol.
- Update for Support differentiated QoS handling for multiplexed media flows TS 23.501CR5783
- Support for MPQUIC-IP and MPQUIC-E steering functionalities TS 23.501CR5493
- Support QoS of proxying IP and Ethernet in HTTP over MPQUIC TS 23.501CR5527
- Handling of UE capability for MPQUIC-IP and MPQUIC-E steering functionalities TS 23.501CR5844
- Support Differentiated QoS handling for encrypted multiplexed media flows TS 23.501CR6042
- Enhancement of 5G ProSe capability for multi-hop relays TS 24.501CR6552
+ 74 more changes
In Release 20, the MPQUIC (Multi-Path QUIC) function was introduced, enabling a QUIC connection to simultaneously use multiple network paths, such as across different accesses, for a single service data flow. This is based on the IETF draft for the Multipath Extension for QUIC, allowing for access traffic splitting to enhance performance and reliability. The specification integrates this new transport capability without defining new architectural network functions, leveraging existing PDU Session and multi-access frameworks.
- Correction on Energy Consumption calculation for redundant transmission or PDU Session with multiple PDU Session Anchors TS 23.501CR6522
Explore further
Broader topics and technologies where MPQUIC plays a role.
Defining Specifications
3GPP specifications that define or reference MPQUIC, 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 24.193 vj50 | ATSSS Procedures Specification | Rel-19 |
| TS 24.501 vj50 | 5G NAS Protocols Specification | Rel-19 |
| TS 26.804 vj10 | 5G Media Streaming Extensions Study | Rel-19 |
| TS 28.552 vk10 | 5G Performance Management Measurements | Rel-20 |
| 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 |
| TR 33.938 vj10 | 3GPP Cryptographic Inventory for 5G | Rel-19 |