5G Base Station Mobility Management for TUPF Area Mapping

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Solution Overview

Problem

The 3GPP standards lack defined mapping between Terminating User Plane Function (TUPF) service areas and cells, leading to incompatibility issues and potential network attachment loss during TUPF relocation, especially for SSC mode 2 PDU sessions, which affects mobility and redirection procedures in 5G networks.

Innovation Solution

A base station controller is configured to manage communication sessions and mobility between cells, initiating handover or redirection procedures based on determining whether the target cell is within the same TUPF serving area as the source cell, and maintaining a mapping between cells, TUPF service areas, and SSC modes to ensure seamless mobility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If TUPF relocation is performed without defined mapping between TUPF service areas and cells, then mobility management flexibility is improved, but network attachment loss occurs and compatibility issues arise

Engineering Contradiction:

Improvemobility management flexibilityVSAvoidnetwork attachment stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The base station performs preliminary determination of whether the target cell is within the same TUPF serving area before executing handover or redirection procedures. This advance checking prevents network attachment loss by ensuring the mobility management entity is properly identified in advance, resolving the contradiction between mobility flexibility and network attachment stability.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary mapping relationship between cells, TUPF service areas, and SSC modes that mediates between the mobility management flexibility and network attachment stability. This mapping structure enables the base station to make informed decisions about handover versus redirection, preventing attachment loss while maintaining mobility flexibility.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Speed

If handover procedure is used without verifying TUPF serving area, then mobility speed is improved, but network attachment loss occurs during TUPF relocation

Engineering Contradiction:

Improvemobility speedVSAvoidnetwork attachment stability

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The base station performs preliminary verification of TUPF serving area membership before initiating handover procedure. This advance checking ensures that handover is only executed when the target cell belongs to the same TUPF serving area, preventing network attachment loss while maintaining fast mobility transitions.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements a feedback mechanism where the base station determines whether the target cell is within the same TUPF serving area and adjusts the mobility procedure accordingly. This feedback loop ensures that handover is used when appropriate (same serving area) and redirection is used when necessary (different serving area), preventing attachment loss while maintaining mobility speed.

Inventive Principle:

Principle #23Feedback

3Adaptability or versatility

If mapping between cells and TUPF service areas is maintained, then compatibility between base stations from different manufacturers is improved, but system complexity increases

Engineering Contradiction:

Improvebase station compatibilityVSAvoidsystem complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements a universal mapping structure that can be applied across base stations from different manufacturers. The mapping between cells, TUPF service areas, and SSC modes provides a standardized interface that enables interoperability while maintaining manageable system complexity through a consistent approach.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent manages system complexity by focusing on key parameters (TUPF serving area identification, SSC mode association) rather than maintaining comprehensive detailed mappings. This parameter-based approach enables base station compatibility while keeping the system complexity manageable through selective tracking of essential mapping information.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11985551B2Mobility in 5G with handoff or cell reselection dependent on change of user-plane functionality serving area

Publication Date: 2024.05.14 NEC CORP

AI summary

A communication system comprises a plurality of cells, each cell being associated with a respective serving area of TUPF. A base station controls a communication session of a communication device via the base station and a TUPF. Mobility of the communication device between a source cell and a target cell is performed as follows: when the communication session uses a nomadic IP address and the target cell is associated with the same TUPF serving area as the source cell but the base station is unable to determine the TUPF serving area of the target cell, the base station initiates a redirection procedure rather than a handover procedure. When performing the redirection procedure, the communication connection for the communication session via the source cell is broken before the target cell has been prepared to receive communication for the communication session of the communication device.