Beam Failure Detection Across RIS Multi-Hop Links

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Solution Overview

Problem

In RIS systems, terminals cannot determine the specific link where beam failure occurs due to the lack of signal processing capability in reconfigurable intelligent surfaces, leading to inefficient beam failure detection and increased measurement complexity.

Innovation Solution

The method involves obtaining measurement values and indication values from different BFD sets to accurately determine beam failures in multiple links, including equivalent, first hop, and second hop links, using a terminal, first node, and network device collaboration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the terminal only reports beam failure detection for an equivalent link from gNB to RIS, then the system maintains simplicity in beam failure detection, but it becomes impossible to determine a specific link where the beam failure occurs

Engineering Contradiction:
Improvebeam failure detection complexityVSAvoidspecific link failure information
Core Design Contradiction:
Device complexityVSLoss of information

Solution Approach 1:

The patent segments the equivalent link into two separate measurable links: the first hop link (gNB to RIS) and the second hop link (RIS to terminal). By introducing separate BFD sets for each hop, the system can independently measure and identify which specific link experiences beam failure, thereby resolving the information loss while maintaining manageable complexity through structured segmentation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces an intermediary measurement mechanism where the terminal measures both the equivalent link and the second hop link separately. This intermediary measurement of the second hop link acts as a mediator to infer the status of the first hop link, enabling specific failure identification without requiring direct measurement capabilities at the RIS.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If the terminal performs measurements on multiple BFD sets to identify specific failure links, then the system achieves precise beam failure identification, but the measurement complexity increases

Engineering Contradiction:
Improvebeam failure location precisionVSAvoidmeasurement process complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The measurement process is segmented into two distinct parts: measuring the equivalent link (first BFD set) and measuring the second hop link (second BFD set). This segmentation allows the terminal to perform focused measurements on each segment separately, improving precision through dedicated measurement sets while managing complexity by organizing measurements into structured, independent tasks rather than a monolithic complex process.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP4654652A1Beam failure detection method and apparatus, and terminal, first node and network device
Publication Date: 2025.11.26 DATANG MOBILE COMM EQUIP CO LTD
  • EP4654652A1 patent drawingFigure 1~3
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  • EP4654652A1 patent drawingFigure 8~11

AI summary

Provided are a beam failure detection method and apparatus, a terminal, a first node and a network device. The method applied to the terminal includes: obtaining a first measurement value, wherein the first measurement value is obtained by the terminal based on a first beam failure detection (BFD) set; obtaining a first indication value, wherein the first indication value is obtained by a first node based on a second BFD set; and determining whether a beam failure occurs to a third BFD set based on the first measurement value and the first indication value.