UE Handover PDCP Processing for Security Key Updates

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Solution Overview

Problem

In next-generation mobile communication systems, when a security key needs to be updated for UE handover, existing methods require discarding all data units and creating new ones, leading to increased data processing complexity, while not updating the key results in inefficiencies.

Innovation Solution

The proposed method distinguishes between cases where the security key needs to be updated and where it does not, implementing different data processing operations for each bearer to reduce complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If security key is updated during handover, then security is improved, but data processing complexity increases due to discarding all data units and creating new ones

Engineering Contradiction:
ImprovesecurityVSAvoiddata processing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies local quality by differentiating data processing operations based on bearer type. For data radio bearers (DRBs), the UE performs PDCP re-establishment when security key is updated, while for signaling radio bearers (SRBs), it performs RRC connection reconfiguration. This localized differentiation reduces unnecessary data processing complexity while maintaining security updates where required.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent segments the handover data processing into distinct procedures based on bearer type. It separates DRB handling (requiring PDCP re-establishment and data unit recreation) from SRB handling (using RRC reconfiguration). This segmentation allows the system to apply security updates only where necessary, reducing overall data processing complexity.

Inventive Principle:
Principle #1Segmentation

2Device complexity

If security key is not updated during handover, then data processing complexity is reduced, but security efficiency deteriorates

Engineering Contradiction:
Improvedata processing complexityVSAvoidsecurity efficiency
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent applies local quality by selectively updating security keys based on bearer type and handover conditions. For DRBs, security key updates are performed with full PDCP re-establishment, while for SRBs, updates are handled through lighter RRC reconfiguration. This ensures security efficiency is maintained where critical while reducing unnecessary updates elsewhere.

Inventive Principle:
Principle #3Local quality

3Reliability

If all data units are discarded and recreated for each bearer, then security is maintained, but productivity decreases due to increased processing overhead

Engineering Contradiction:
ImprovesecurityVSAvoidhandover efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent applies local quality by differentiating data processing operations based on bearer type. For data radio bearers (DRBs), the UE performs PDCP re-establishment when security key is updated, while for signaling radio bearers (SRBs), it performs RRC connection reconfiguration. This localized differentiation reduces unnecessary data processing complexity while maintaining security updates where required.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent applies partial action by performing complete PDCP re-establishment only for DRBs when security key updates are required, while using lighter RRC reconfiguration for SRBs. This partial application of the full re-establishment procedure maintains security where critical while avoiding excessive processing overhead for other bearers.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP3857964B1Method and apparatus for performing handover in mobile communication system
Publication Date: 2025.12.10 SAMSUNG ELECTRONICS CO LTD
  • EP3857964B1 patent drawingFigure 1A
  • EP3857964B1 patent drawingFigure 1B~1C
  • EP3857964B1 patent drawingFigure 1D~1E

AI summary

A method of performing communication, by a user equipment (UE), in a wireless communication system, the method including receiving a radio resource control (RRC) message including a handover command, identifying whether a security key is updated based on the RRC message, and performing a packet data convergence protocol (PDCP) process based on a bearer type and a result of the identification.