RLM Reference Signal Configuration for Non-CSI-RS UEs

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Solution Overview

Problem

UEs that do not support CSI-RS based radio link monitoring (RLM) face challenges in configuring appropriate RLM reference signals, leading to potential radio link failures and service interruptions.

Innovation Solution

A method where UEs transmit an indication of their RLM capability to the base station, allowing the base station to determine and configure a suitable RLM reference signal configuration for the UE, enabling RLM through either explicit or implicit SSB-based configurations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If UEs use CSI-RS based RLM configuration, then RLM performance is improved, but device complexity increases due to requiring advanced UE capabilities

Engineering Contradiction:

ImproveRLM performanceVSAvoidUE capability requirements

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the RLM capability into different levels: UEs are divided into those that support CSI-RS based RLM and those that do not. This segmentation allows the system to provide differentiated configurations, ensuring that UEs with limited capabilities can still perform RLM using alternative reference signals while more advanced UEs can utilize the superior CSI-RS based monitoring.

Inventive Principle:

Principle #1Segmentation

2Duration of action of stationary object

If UEs without CSI-RS support perform RLM, then service continuity is improved, but configuration complexity increases at the base station

Engineering Contradiction:

Improveservice continuityVSAvoidbase station configuration complexity

Core Design Contradiction:

Duration of action of stationary objectVSDevice complexity

Solution Approach 1:

The patent implements a feedback mechanism where the UE reports its RLM capability to the base station. Based on this feedback, the base station automatically selects and configures the appropriate RLM reference signal type (CSI-RS or SSB). This feedback-driven approach simplifies the base station's configuration process by eliminating the need for manual assessment of UE capabilities and reduces configuration errors.

Inventive Principle:

Principle #23Feedback

3Adaptability or versatility

If explicit SSB-based RLM configuration is used for non-CSI-RS UEs, then compatibility is improved, but signaling overhead increases

Engineering Contradiction:

ImproveUE compatibilityVSAvoidsignaling overhead

Core Design Contradiction:

Adaptability or versatilityVSLoss of information

Solution Approach 1:

The patent applies preliminary action by having the base station configure the RLM reference signal parameters in advance through RRC signaling before the UE actually performs RLM. The configuration includes pre-defining the SSB resources and associated parameters, so that when the UE needs to perform RLM, the configuration is already in place and ready for use, reducing the need for additional dynamic signaling.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS11405809B2Radio link monitoring reference signals for UEs that do not support CSI-RS based radio link monitoring

Publication Date: 2022.08.02 QUALCOMM INC

AI summary

A configuration to improve the manner in which a UE is configured to perform RLM for UEs that do not support CSI-RS based RLM. The apparatus may transmit, to a base station, an indication including a RLM capability. The apparatus may receive, from the base station, a RLM RS configuration from the UE based on the indication. The apparatus determines the RLM RS configuration for the UE, based on the RLM RS configuration received from the base station.