Wireless Terminal RLM Continuity After DL BWP Switching

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Solution Overview

Problem

The uncertainty in determining which reference signal (RS) a radio terminal should monitor for Radio Link Monitoring (RLM) after switching of the Downlink (DL) active Bandwidth Part (BWP) in a 5G communication system is unresolved.

Innovation Solution

The radio terminal is configured to continue monitoring a specific RS type, such as CSI-RS or SSB, for RLM measurements after BWP switching, based on the initial RS type configuration, without requiring additional RRC signaling, thereby maintaining consistent RLM parameters and measurements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the radio terminal switches DL active BWP dynamically, then the system adaptability and resource utilization are improved, but the uncertainty in determining which RS to monitor for RLM increases

Engineering Contradiction:
ImproveBWP switching capabilityVSAvoidRLM RS identification uncertainty
Core Design Contradiction:
Adaptability or versatilityVSLoss of information

Solution Approach 1:

The patent applies preliminary action by configuring the RS type (CSI-RS or SSB) for RLM measurements in advance through RRC signaling before BWP switching occurs. When the DL active BWP is switched, the terminal continues to use the pre-configured RS type for RLM measurements, eliminating the need to重新 determine which RS to monitor. This preliminary configuration resolves the uncertainty problem while maintaining adaptability through dynamic BWP switching.

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If additional RRC signaling is used to specify RS type after BWP switching, then the RLM measurement accuracy is improved, but the signaling overhead increases

Engineering Contradiction:
ImproveRLM measurement accuracyVSAvoidsignaling overhead
Core Design Contradiction:
Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent applies self-service by enabling the terminal to autonomously continue using the pre-configured RS type for RLM measurements after BWP switching, without requiring additional network signaling. The terminal self-determines that the originally configured RS type remains valid, thereby achieving accurate RLM measurements while avoiding extra signaling overhead. This self-service mechanism resolves the contradiction between measurement precision and signaling quantity.

Inventive Principle:
Principle #25Self-service

3Reliability

If the RS type for RLM is reconfigured after BWP switching, then the measurement reliability is improved, but the system complexity and processing time increase

Engineering Contradiction:
ImproveRLM measurement reliabilityVSAvoidRLM configuration management complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies continuity of useful action by maintaining the same RS type configuration for RLM measurements before and after BWP switching. The pre-configured RS type continues to be used without interruption or reconfiguration, ensuring continuous and reliable RLM measurements. This approach simplifies the system by avoiding complex reconfiguration procedures while maintaining measurement reliability through the persistent use of the originally configured RS.

Inventive Principle:
Principle #20Continuity of useful action

Data Source

PatentEP3713333B1Wireless terminal and method therefor
Publication Date: 2025.07.02 NEC CORP
  • EP3713333B1 patent drawingFigure 1~2
  • EP3713333B1 patent drawingFigure 3~5
  • EP3713333B1 patent drawingFigure 6~7

AI summary

When a downlink bandwidth part (BWP) is switched from a first BWP to a second BWP without a change of a cell defining synchronization signal block (SSB), if a reference signal type for Radio Link Monitoring (RLM) is set to an SSB type, a radio terminal (12) continues to use for RLM measurements a first SSB associated with the first BWP after switching of the downlink BWP to the second BWP. This for example enables the radio terminal to monitor a suitable Reference Signal (RS) for RLM measurements after switching of the DL active BWP.