RLC Retransmission Error Reporting in Dual Connectivity

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Solution Overview

Problem

In wireless communication systems, particularly in dual connectivity scenarios, existing methods for handling RLC retransmission errors are inefficient, leading to wastage of radio resources and prolonged recovery times due to the need for re-establishing RRC connections, especially when errors occur in secondary cells with non-ideal backhaul connections.

Innovation Solution

A method where the UE stops transmitting further RLC PDUs and reports RLC retransmission errors to the primary base station without initiating RRC connection re-establishment, allowing for localized recovery of radio bearers served by secondary base stations, thereby conserving resources and reducing recovery time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If RRC connection re-establishment is initiated upon RLC retransmission error, then reliability is improved, but loss of time and productivity deteriorate due to prolonged recovery times and resource wastage

Engineering Contradiction:
ImprovereliabilityVSAvoidrecovery time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent segments the error handling process by distinguishing between RLC layer errors and RRC layer errors. Instead of uniformly triggering RRC re-establishment for all RLC errors, the solution segments the response based on error location and type, allowing localized RLC recovery for secondary cell errors while preserving RRC connection stability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies local quality by enabling differentiated error handling for different cells. Primary cells maintain traditional RRC re-establishment behavior for high reliability, while secondary cells with non-ideal backhaul use localized RLC recovery mechanisms to minimize disruption and reduce recovery time without compromising overall system reliability.

Inventive Principle:
Principle #3Local quality

2Reliability

If RRC connection re-establishment is initiated upon RLC retransmission error, then reliability is improved, but device complexity and loss of energy worsen due to unnecessary full connection re-establishment

Engineering Contradiction:
ImprovereliabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the error handling protocol into two distinct paths: one for primary cell errors requiring RRC re-establishment, and another for secondary cell errors handled at the RLC layer. This segmentation reduces unnecessary full connection re-establishment procedures, simplifying the overall system operation while maintaining reliability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies partial action by implementing localized RLC recovery for secondary cell errors instead of performing the complete RRC re-establishment procedure. This partial recovery mechanism addresses the specific error without triggering unnecessary full-scale connection re-establishment, reducing device complexity and energy consumption while maintaining adequate reliability.

Inventive Principle:
Principle #16Partial or excessive action

3Productivity

If localized RLC recovery is implemented for secondary cells, then productivity is improved by reducing recovery time, but reliability may worsen without full RRC re-establishment

Engineering Contradiction:
ImproveproductivityVSAvoidreliability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent applies local quality by implementing differentiated reliability mechanisms for different cell types. Secondary cells use localized RLC recovery for fast productivity improvement, while primary cells maintain traditional RRC re-establishment for high reliability assurance. This localized approach optimizes the reliability-productivity tradeoff for each cell type appropriately.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent introduces an intermediary error handling layer at the RLC level for secondary cells, acting as a mediator between the physical layer errors and the RRC connection. This intermediary RLC recovery mechanism provides fast local remediation for secondary cell errors, improving productivity while maintaining adequate reliability through the additional safety net of RRC monitoring.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP3022963B1Method for reporting a radio link control re-transmission failure and a device therefor
Publication Date: 2021.10.20 LG ELECTRONICS INC
  • EP3022963B1 patent drawingFigure 1
  • EP3022963B1 patent drawingFigure 2A
  • EP3022963B1 patent drawingFigure 2B

AI summary

The present invention relates to a wireless communication system. More specifically, the present invention relates to a method and a device for reporting an RLC (Radio Link Control) re-transmission failure in the wireless communication system, the method comprising: communicating with both the first BS and the second BS, wherein the first BS has a Radio Resource Control (RRC) connection with the UE; and reporting to the first BS, a Radio Link Control (RLC) retransmission error without RRC connection re-establishment for the first BS if the RLC retransmission error occurs in an RLC entity transmitting RLC PDU (Protocol Data Unit) to the second BS.