Groupcast L2 Identifier Rotation to Reduce UE Trackability

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Solution Overview

Problem

Existing security mechanisms for 5G V2X groupcast communication do not adequately protect against the risk of UE trackability through Layer 2 (L2) identifiers, as destination L2 identifiers in groupcast communication can be fixed and used by eavesdroppers to trace UEs.

Innovation Solution

Introduce group-specific destination L2 identifiers that are periodically changed or responsive to events, using privacy parameters provisioned during authorization, ensuring the UE selects and updates these identifiers to maintain privacy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If fixed destination L2 identifiers are used in groupcast communication, then communication efficiency is improved, but UE trackability risk increases

Engineering Contradiction:
Improvecommunication efficiencyVSAvoidUE trackability risk
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent applies dynamics by making the destination L2 identifier changeable rather than fixed. The UE dynamically selects from multiple group-specific destination L2 identifiers and periodically updates the current identifier, transforming the static identifier system into a dynamic one that balances communication efficiency with privacy protection.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements periodic action through regular updates of the current destination L2 identifier. The UE periodically changes the identifier from a set of group-specific identifiers, creating time-based variations that prevent continuous tracking while maintaining efficient groupcast communication during each period.

Inventive Principle:
Principle #19Periodic action

2Object-affected harmful factors

If source L2 identifier is changed frequently, then privacy protection is improved, but communication overhead increases

Engineering Contradiction:
Improveprivacy protectionVSAvoidcommunication overhead
Core Design Contradiction:
Object-affected harmful factorsVSLoss of information

Solution Approach 1:

The patent applies segmentation by dividing the identifier space into multiple group-specific destination L2 identifiers. Instead of changing the source identifier frequently, the UE segments the destination identifier options and rotates through them, reducing the frequency of changes needed while maintaining privacy protection.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent uses parameter changes by modifying the destination L2 identifier parameter rather than the source L2 identifier. This parameter substitution allows privacy protection through identifier changes without the same overhead implications, as the destination identifier is naturally less critical for communication establishment.

Inventive Principle:
Principle #35Parameter changes

3Object-affected harmful factors

If group-specific destination L2 identifiers are introduced, then UE trackability is mitigated, but system complexity increases

Engineering Contradiction:
ImproveUE trackabilityVSAvoidsystem complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent applies universality by designing group-specific destination L2 identifiers that serve multiple functions: they identify the target group for communication, provide privacy protection through rotation, and enable efficient groupcast without requiring separate mechanisms. This multi-functionality reduces overall system complexity despite the introduction of new identifier management.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent implements self-service by enabling the UE to autonomously manage its own destination L2 identifier selection and updates. The UE independently selects from the group-specific identifiers and performs periodic updates without requiring network intervention, reducing signaling overhead and system complexity while maintaining privacy protection.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP4042733B1Security for groupcast message in d2d communication
Publication Date: 2025.12.31 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP4042733B1 patent drawingFigure 1
  • EP4042733B1 patent drawingFigure 2
  • EP4042733B1 patent drawingFigure 3

AI summary

The present disclosure provides a security mechanism to mitigate the risk of trackability of a D2D device engaged in groupcast communication. The security mechanism relies on the introduction of new parameters provisioned to the UE to facilitate the privacy protection of destination L2 identifiers used during group communication. The new parameters allow the UE to change the destination L2 Identifier so that an eavesdropper on the PC5 interface can no longer link several broadcast messages originating from the source UE and pertaining to a specific group.