Terminal Reference Signal Control for Multi-Cell RLM and BFR

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Solution Overview

Problem

In next-generation mobile communication systems, determining the appropriate reference signal (RS) for radio link monitoring (RLM), beam failure detection (BFD), and beam failure recovery (BFR) is unclear when multiple cells are used, particularly for cells with different physical cell IDs (PCI).

Innovation Solution

A terminal equipped with a receiving section for receiving reference signals associated with a second physical cell ID different from the serving cell's ID and a control section to manage RLM, BFD, and BFR using these signals, allowing for appropriate determination and control of RSs across multiple cells.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a terminal uses multiple cells with different PCIs for communication, then the coverage and capacity of the network are improved, but the determination of appropriate reference signals for RLM, BFD, and BFR becomes unclear and unreliable

Engineering Contradiction:

Improvemulti-cell communication capabilityVSAvoidreference signal determination reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies local quality by differentiating the determination rules for reference signals based on the specific cell type (serving cell vs. non-serving cell) and the specific function (RLM, BFD, or BFR). Each cell type and function combination has its own designated reference signal source, ensuring reliable determination even in multi-cell environments with different PCIs.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent segments the reference signal determination process into distinct rules for different functions: RLM uses reference signals from the serving cell, while BFD and BFR use reference signals from non-serving cells. This segmentation eliminates confusion and ensures each function has a clear, appropriate reference signal source.

Inventive Principle:

Principle #1Segmentation

2Measurement precision

If reference signals from non-serving cells are used for BFD and BFR, then beam failure detection and recovery accuracy is improved, but the complexity of managing multiple reference signals across different cells increases

Engineering Contradiction:

Improvebeam failure detection accuracyVSAvoidreference signal management complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies universality by using the same reference signal (CSI-RS or SSB) from non-serving cells for multiple purposes: both beam failure detection and beam failure recovery. This multi-functional approach improves accuracy without requiring separate reference signals for each function, thereby managing complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS20250106080A1Terminal, radio communication method, and base station

Publication Date: 2025.03.27 NTT DOCOMO INC

AI summary

A terminal according to one aspect of the present disclosure includes: a receiving section that receives a reference signal associated with a second physical cell ID (PCI) different from a first physical cell ID (PCI) corresponding to a serving cell; and a control section that controls, by using the reference signal, at least one of radio link monitoring (RLM), beam failure detection (BFD), and beam failure recovery (BFR). According to one aspect of the present disclosure, an RS to be used for at least one of the RLM, BFD, and BFR can be appropriately determined.