Multi-Access PDU Session Establishment in 5G Core Networks
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Solution Overview
Problem
Existing PDU session establishment methods in 5G networks are limited to single access networks, preventing the transmission or reception of user traffic through multiple access networks, which hinders the implementation of advanced traffic steering, switching, and splitting functions.
Innovation Solution
A method and network entity for establishing a multi-access PDU session by registering user equipment with both 3GPP and non-3GPP access networks, using NAS messages to request PDU session creation and updates, and involving AMF, SMF, and PCF to manage and authorize the session across multiple access networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a PDU session is established through a single access network, then the session establishment process is simple and straightforward, but user traffic cannot be transmitted or received through multiple access networks
Solution Approach 1:
The patent segments the PDU session establishment process into distinct phases: initial SA-PDU session establishment through one access network, followed by a separate extension phase where the UE requests MA-PDU session capability. This segmentation allows the system to maintain simple initial establishment while adding multi-access capability through a structured extension process involving specific NAS messages and network function interactions.
Solution Approach 2:
The patent applies preliminary action by first establishing a basic SA-PDU session through a single access network before extending it to multi-access capability. The UE preliminarily establishes registration and basic session parameters, then subsequently requests MA-PDU session extension through a PDU session establishment request message containing an MA-PDU request indication. This preliminary establishment simplifies the overall process by building upon an already-configured single-access session.
2Adaptability or versatility
If existing SA-PDU session establishment methods are used, then the implementation is straightforward with single access network support, but advanced ATSSS functions cannot be provided
Solution Approach 1:
The patent changes key parameters in the PDU session establishment request message to enable ATSSS functions. Specifically, it introduces an MA-PDU request indication parameter that distinguishes MA-PDU session requests from traditional SA-PDU session requests. This parameter change triggers different handling by the AMF and SMF, enabling advanced traffic steering, switching, and splitting functions while maintaining compatibility with existing session establishment procedures for non-ATSSS cases.
Solution Approach 2:
The patent introduces intermediary elements to bridge existing SA-PDU session mechanisms with new ATSSS requirements. The AMF acts as an intermediary that receives the PDU session establishment request with MA-PDU indication, validates it, and coordinates with the SMF to establish the MA-PDU session. This intermediary role allows the system to maintain ease of operation by using familiar message formats while enabling advanced ATSSS functions through coordinated interaction between network functions.
3Adaptability or versatility
If a PDU session is established only through one access network, then the session management is simple, but traffic cannot be steered, switched, or split across multiple access networks
Solution Approach 1:
The patent applies dynamics by enabling the PDU session to transition from a static single-access configuration to a dynamic multi-access configuration. The MA-PDU session allows the session to adaptively utilize multiple access networks (3GPP and non-3GPP) based on traffic requirements, network conditions, and ATSSS policies. This dynamic capability enables traffic steering, switching, and splitting functions while the underlying session management structure remains based on the established SA-PDU session framework, balancing versatility with manageable complexity.
Data Source
AI summary
A packet data unit session establishment method and network entity performing the same is disclosed. User equipment (UE) may establish registration with the core network through a first access network when the UE is registered in a core network through a second access network belonging to the network and a first PDU session is established through the second access network. The UE may transmit a non-access stratum (NAS) message including a PDU session identifier (ID) that is the same as an ID of the first PDU session to an access and mobility management function (AMF).