User Terminal RLM Control During RRC Reconfiguration

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Solution Overview

Problem

In future radio communication systems, such as LTE Rel. 15 and 5G, the reconfiguration of RRC connections for RLM-RS configurations leads to improper control of RLM behavior, resulting in inadequate detection of radio link failures (RLF).

Innovation Solution

A user terminal is equipped with a receiving section to handle RRC connection reconfiguration messages for RLM-RS configurations, and a control section that manages RLM behavior during reconfiguration, including discontinuing or continuing RLM activities based on received messages to ensure proper RLF detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If RRC connection reconfiguration is performed for RLM-RS configuration in future radio communication systems, then the measurement reference signal configuration can be updated to improve system adaptability, but the RLM behavior cannot be properly controlled during reconfiguration leading to improper RLF detection

Engineering Contradiction:

ImproveRLM-RS configuration update capabilityVSAvoidRLF detection accuracy

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies preliminary action by controlling RLM behavior in advance during RRC connection reconfiguration. The base station transmits control information indicating whether to continue or discontinue RLM before the reconfiguration is completed, ensuring that RLF detection is properly managed throughout the reconfiguration process rather than reacting after problems occur.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If RLM behavior is controlled during RRC connection reconfiguration, then RLF detection accuracy is improved, but the system complexity increases due to additional control mechanisms

Engineering Contradiction:

ImproveRLF detection accuracyVSAvoidcontrol mechanism complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies universality by using the existing RRC connection reconfiguration message to carry dual-purpose information: both the RLM-RS configuration update and the RLM behavior control indication. This multi-functionality approach allows the system to control RLF detection accuracy without adding separate dedicated control channels or mechanisms, thereby avoiding excessive system complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If RLM is discontinued during RRC connection reconfiguration, then false RLF detection is prevented, but the monitoring of radio link quality is interrupted during a critical period

Engineering Contradiction:

Improvefalse RLF detection preventionVSAvoidRLM interruption duration

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies dynamics by making the RLM behavior flexible and adaptable during RRC connection reconfiguration. Instead of a fixed approach, the system dynamically adjusts RLM behavior based on the specific reconfiguration scenario - choosing to continue, discontinue, or modify RLM operations according to the type of reconfiguration and system conditions, thereby preventing false detections while minimizing monitoring interruptions.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentEP3739935B1User terminal and radio communication method

Publication Date: 2024.04.17 NTT DOCOMO INC

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AI summary

A user terminal includes a receiving section that receives an RRC (Radio Resource Control) connection reconfiguration message including configuration information of a measurement reference signal for a radio link quality in radio link monitoring (RLM), and a control section that controls an RLM behavior concerning the RLM during an RRC connection reconfiguration based on the RRC connection reconfiguration message.