Network-Initiated PDU Session Establishment in 5G AMF
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Solution Overview
Problem
Current 5G telecommunication networks lack a mechanism for network-initiated PDU session establishment between User Equipment (UE) and Data Network Names (DNN), which is necessary for services like IMS voice, where continuous PDU sessions are required, unlike in 4G/LTE systems.
Innovation Solution
The Access and Mobility Function (AMF) initiates PDU sessions by retrieving DNNs from the Unified Data Management (UDM) during UE registration, instructing the UE to establish the necessary sessions, allowing the network to decide which PDU sessions to establish and ensuring their availability for services like IMS voice.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If PDU session establishment is left to UE initiation only, then UE autonomy and simplicity are improved, but network ability to ensure continuous connections for services like IMS voice deteriorates
Solution Approach 1:
The network performs preliminary action by retrieving subscribed DNNs from UDM during UE registration and storing them in AMF. This preliminary preparation enables the network to later instruct UE to establish specific PDU sessions without requiring complex real-time decisions, thus ensuring continuous connection availability while maintaining UE simplicity.
Solution Approach 2:
The AMF acts as an intermediary between the network and UE. It receives subscription data from UDM, processes it, and then instructs the UE to establish appropriate PDU sessions. This intermediary role enables the network to control session establishment while the UE simply executes the instructions, resolving the contradiction between network control and UE simplicity.
2Reliability
If network initiates PDU session establishment during registration, then service delivery reliability is improved, but registration procedure complexity increases
Solution Approach 1:
The AMF performs preliminary action by retrieving subscribed DNNs from UDM during the registration procedure. This preliminary data retrieval is done as part of the standard registration flow, so it doesn't add extra complexity to the registration procedure itself, while still enabling the network to guarantee service delivery by having the data ready beforehand.
Solution Approach 2:
The AMF uses existing registration messages and procedures to convey the DNN list to the UE. The UE autonomously processes the received DNN list and establishes the necessary PDU sessions without requiring additional complex signaling. This self-service approach allows the network to ensure service delivery while keeping the registration procedure simple.
3Speed
If default APN/DNN is automatically assigned during attach/registration, then connection speed is improved, but network flexibility to control specific sessions deteriorates
Solution Approach 1:
The network performs preliminary action by pre-retrieving and storing subscribed DNNs in the AMF during UE registration. This preliminary preparation allows the network to later quickly instruct the UE to establish specific PDU sessions without needing to perform complex real-time decisions, thus maintaining fast connection establishment while preserving network flexibility to control which sessions are created.
Solution Approach 2:
The AMF serves as an intermediary that holds the DNN list retrieved from UDM. When the UE needs to establish a PDU session, the AMF provides the appropriate DNN information, enabling the network to control which sessions are established while the process remains simple and fast for the UE.
Data Source
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AI summary
A method of initiating a Packet Data Unit, PDU, session between an User Equipment, UE, and a Data Network Name, DNN, in a telecommunication network, said method comprising the steps of; receiving, by an Access & Mobility Function, AMF, a registration request for an UE for registering said UE in said telecommunication network, retrieving, by said AMF, from an Unified Data Management, UDM, node, one or more DNNs to which PDU sessions are expected to be established by said UE in said telecommunication network, and wherein said step of retrieving is triggered by said receiving of said registration request, instructing, by said AMF, said UE to initiate said one or more PDU sessions between said UE and said one or more DNNs. Complementary methods and Devices for performing a method according to the invention are also presented herein.