Unified Split Bearer Reconfiguration for LTE-NR Bearer Changes

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Solution Overview

Problem

Current models face challenges in managing bearer type changes, particularly in Fifth Generation New Radio (5G NR) systems, including difficulties in merging MCG and SCG split bearers, identifying the need for PDCP and RLC re-establishment, and handling security configuration changes during UE mobility, especially in LTE-NR dual connectivity.

Innovation Solution

The solution involves unifying MCG and SCG split bearers into a single split bearer type, using a neutral PDCP entity not directly associated with MN or SN stacks, and employing separate PDCP configuration containers to manage bearer type changes, along with MAC reset avoidance techniques like LCID allocation and PDCP header toggling to ensure lossless data transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If RRC connection re-establishment is performed when PSCell is released, then connection reliability is improved, but unnecessary RRC operations and signaling overhead increase

Engineering Contradiction:
Improveconnection reliabilityVSAvoidRRC operation complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent changes the parameter being monitored from PSCell release event to beam failure detection event. By detecting beam failure through specific beam failure indicators and triggering RRC re-establishment only when beam failure occurs, the system avoids unnecessary RRC operations while maintaining connection reliability. This parameter change allows selective triggering based on actual communication quality rather than cell release status.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces beam failure detection as an intermediary mechanism between PSCell release and RRC re-establishment. Instead of directly triggering RRC re-establishment upon PSCell release, the system first detects beam failure through intermediate indicators (such as reference signal quality measurements), then decides whether RRC re-establishment is necessary. This intermediary layer filters out unnecessary re-establishment operations.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Stability of the object's composition

If RRC connection re-establishment is triggered by PSCell release, then connection stability is improved, but signaling overhead and network load increase

Engineering Contradiction:
Improveconnection stabilityVSAvoidsignaling overhead
Core Design Contradiction:
Stability of the object's compositionVSLoss of information

Solution Approach 1:

The patent changes the triggering parameter from PSCell release to beam failure detection. By monitoring beam-specific quality parameters (reference signal received power/quality) rather than cell-level release events, the system triggers RRC re-establishment only when actual communication quality degrades below acceptable thresholds, reducing unnecessary signaling overhead while maintaining connection stability.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies partial action by selectively triggering RRC re-establishment only when beam failure is detected, rather than triggering it for all PSCell release events. This partial triggering approach reduces the frequency of RRC operations and associated signaling overhead while maintaining adequate connection stability for cases that actually require re-establishment.

Inventive Principle:
Principle #16Partial or excessive action

3Measurement precision

If beam failure detection is added for SCell, then communication quality is improved, but device complexity and processing overhead increase

Engineering Contradiction:
Improvecommunication quality measurementVSAvoiddetection mechanism complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent makes the beam failure detection mechanism universal by applying the same detection logic across multiple cells (PCell and SCells). The detection mechanism uses standardized reference signal quality measurements that are already part of the system's existing measurement framework, allowing the same multi-functional measurement infrastructure to serve both cell types without requiring separate complex detection systems.

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

Solution Approach 2:

The system uses existing reference signal measurements (CSI-RS or SSB) that are already being transmitted and measured for other purposes (channel quality estimation, beam management). By reusing these existing signals for beam failure detection, the system avoids adding separate dedicated detection signals or mechanisms, thereby reducing the increase in device complexity while improving measurement precision.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP3639618B1L2 handling for bearer type change
Publication Date: 2026.05.20 APPLE INC
  • EP3639618B1 patent drawingFigure 1
  • EP3639618B1 patent drawingFigure 2A~2B
  • EP3639618B1 patent drawingFigure 3A~3B

AI summary

An apparatus of an evolved Node B or a Fifth Generation Node B comprises one or more baseband processors to generate an RRCConnectionReconfiguration message to include an information element (IE) to configure a user equipment (UE) to receive data from a Long-Term Evolution node and from a New Radio node in a unified split bearer configuration and encode data to be transmitted to the UE via a master cell group bearer, a secondary cell group bearer, or a unified split bearer. The baseband processors further are to encode an IE of an RRCReconfiguration message to configure a data radio bearer as a Packet Data Convergence Protocol and higher layers configuration coupled with one or more logical channels of radio link control and below, and to configure a change between a single connectivity bearer to multi-connectivity bearer by configuring or releasing one or more of the logical channels.