RRC Inactive PTM Configuration for Multicast Service Continuity

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Solution Overview

Problem

Existing wireless communication systems face challenges in maintaining service continuity for multicast-broadcast services during radio resource control state transitions, particularly when UEs transition from RRC connected mode to RRC inactive mode, due to differences in multicast radio bearer configurations and the lack of explicit MRB ID information in RRC inactive mode configurations.

Innovation Solution

The proposed solution involves maintaining separate PTM configurations for multicast reception in RRC connected and inactive modes, providing MRB ID information in RRC release messages for RRC inactive mode, and ensuring seamless service continuity by configuring UEs with appropriate PDCP and RLC entities, allowing UEs to continue receiving multicast data traffic across mode transitions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multicast reception is not supported in RRC inactive mode, then device complexity is reduced, but service continuity and reliability deteriorate

Engineering Contradiction:
Improveservice continuityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the multicast reception capability by RRC state, allowing UE to receive multicast data in both RRC connected and inactive modes with different configuration mechanisms. This enables reliable service continuity while managing device complexity through state-specific handling

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements universal multicast reception capability across different RRC states (connected and inactive), allowing the same UE to maintain multicast service continuity regardless of state transitions. This multi-functionality approach ensures reliability without requiring separate dedicated systems for each state

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

2Reliability

If separate processing is used for MBS broadcast and unicast reception, then reliability is improved, but device complexity and resource utilization worsen

Engineering Contradiction:
Improveservice continuityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the processing of MBS broadcast and unicast reception by allowing a single PDCP entity to handle both types of traffic. This reduces device complexity and resource utilization while maintaining service continuity through unified processing mechanisms

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent implements a universal PDCP entity that can process both broadcast and unicast MBS traffic, eliminating the need for separate processing paths. This multi-functional approach reduces complexity while ensuring reliable service delivery across different transmission types

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

3Reliability

If multicast configuration is not maintained during state transition, then device complexity is reduced, but information loss and service continuity deteriorate

Engineering Contradiction:
Improveservice continuityVSAvoidconfiguration information
Core Design Contradiction:
ReliabilityVSLoss of information

Solution Approach 1:

The patent applies preliminary action by configuring the UE with multicast configuration information before state transition to inactive mode. The network provides necessary configuration data in advance, ensuring that the UE can maintain multicast reception without losing critical configuration information during state transitions

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent ensures continuity of useful action by maintaining multicast configuration information across RRC state transitions. The configuration is preserved and remained valid when transitioning between connected and inactive modes, preventing information loss and ensuring uninterrupted service

Inventive Principle:
Principle #20Continuity of useful action

Data Source

PatentEP4503667B1Systems and methods for multicast data traffic service continuity under multicast-broadcast services operation during radio resource control state transition
Publication Date: 2026.05.13 APPLE INC
  • EP4503667B1 patent drawingFigure 1A
  • EP4503667B1 patent drawingFigure 1B
  • EP4503667B1 patent drawingFigure 1C

AI summary

Systems and methods for multicast data traffic service continuity under multicast-broadcast services (MBS) operation during a radio resource control (RRC) state or mode transition are described. In some embodiments, a user equipment (UE) receives, from a network, while in an RRC connected mode, an RRC release message comprising an RRC inactive mode point to multipoint (PTM) configuration that uses an MBS session to receive multicast data traffic while the UE is in an RRC inactive mode; enters the RRC inactive mode from the RRC connected mode in response to the RRC release message; and uses the RRC inactive mode PTM configuration to receive, from the network, the multicast data traffic of the MBS session while the UE is in the RRC inactive mode. Cases where a UE instead re-uses an RRC connected mode PTM configuration after transitioning to the RRC inactive mode are also described. Analogous network behaviors are described.