On-Demand S-NSSAI Timer Synchronization for UE-AMF Slice Deregistration

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Solution Overview

Problem

There is a mismatch in the operation of the slice deregistration inactivity timer between the User Equipment (UE) and the Access and Mobility Management Function (AMF) in wireless communication networks, leading to inefficiencies in managing network slice selection assistance information.

Innovation Solution

The method involves the UE and AMF synchronizing the slice deregistration inactivity timer by starting or stopping it based on conditions such as the release or establishment of Multi-Access Protocol Data Unit (MA PDU) sessions and user plane resources, ensuring alignment and handling mismatches through the use of a slice deregistration inactivity timer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the slice deregistration inactivity timer is started independently at UE and AMF without synchronization, then each entity can autonomously manage its timer operation, but a mismatch occurs between UE and AMF timer operations leading to inefficient network slice management

Engineering Contradiction:

Improveautonomous timer managementVSAvoidtimer operation alignment

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent implements feedback mechanisms where the UE reports PDU session status changes to the AMF, and the AMF responds by providing slice deregistration inactivity timer values. This feedback loop ensures both entities have synchronized timer operations while maintaining autonomous management capabilities.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The AMF provides the slice deregistration inactivity timer value to the UE in advance during registration procedures or configuration updates, before the timer operations begin. This preliminary action ensures both entities start with the same timer configuration, preventing mismatches.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If the slice deregistration inactivity timer value is updated at AMF, then the AMF can optimize network slice management, but the UE may not receive the updated value leading to inconsistency

Engineering Contradiction:

Improvenetwork slice management efficiencyVSAvoidtimer value synchronization

Core Design Contradiction:

ProductivityVSLoss of information

Solution Approach 1:

The patent establishes a feedback channel where the UE sends PDU session status information to the AMF, enabling the AMF to push updated timer values to the UE when changes occur. This ensures the UE always has the current timer value without requiring continuous polling.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The UE Configuration Update Command message serves multiple functions: it can update the UE's allowed NSSAI, update the slice deregistration inactivity timer value, and trigger timer operations. This multi-functionality ensures consistent state synchronization across both entities.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Speed

If the UE autonomously determines when to start the slice deregistration inactivity timer based on local PDU session release, then the UE can react quickly to local conditions, but the AMF may not be aware of the timer operation causing mismatch

Engineering Contradiction:

Improvetimer activation response timeVSAvoidUE-AMF timer state alignment

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

When the UE autonomously starts the slice deregistration inactivity timer based on PDU session release, it immediately notifies the AMF by setting the PDU session status to inactive. The AMF, upon receiving this status change, starts its corresponding timer, ensuring both entities remain synchronized despite autonomous activation.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The UE is pre-configured with the slice deregistration inactivity timer value and the conditions for timer activation during registration or configuration updates. This allows the UE to autonomously and quickly activate the timer when conditions are met, while the AMF is prepared to respond to status changes.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS20250358766A1Handling mismatch of allowed single network slice selection assistance information

Publication Date: 2025.11.20 SAMSUNG ELECTRONICS CO LTD

AI summary

The disclosure relates to a fifth-generation (5G) or sixth-generation (6G) communication system for supporting a higher data transmission rate. A method performed by a terminal in a communication system is provided. The method includes transmitting, to an access and mobility management function (AMF), a registration request message, receiving, from the AMF, a registration accept message for the registration request message, the registration accept message including information on an on-demand single network slice selection assistance information (S-NSSAI), the information on the on-demand S-NSSAI including the on-demand S-NSSAI and a value of a slice deregistration inactivity timer associated with the on-demand S-NSSAI, and in case that a condition is satisfied, starting the slice deregistration inactivity timer for the on-demand S-NSSAI over an access type, using the value. The condition is satisfied in case that a multi-access (MA) protocol data unit (PDU) session associated with the on-demand S-NSSAI is released for each registered access type, there is no PDU session associated with the on-demand S-NSSAI and there are no established user plane resources of the MA PDU session over the access type, or in case that user plane resources of the MA PDU session are released over the access type, there is no PDU session associated with the on-demand S-NSSAI and there are no established user plane resources of the MA PDU session over the access type.