Thresholded Beam Failure Counting for Random Access Preamble Recovery

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Solution Overview

Problem

Future radio communication systems face challenges in effectively controlling beam recovery procedures to prevent radio link failures due to beam failures, which can lead to frequent reconnections and reduced system throughput.

Innovation Solution

A user terminal increments a beam failure instance counter based on beam failure indications from the physical layer and transmits a random access preamble when the counter reaches a threshold, allowing for controlled beam recovery through higher layer signaling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If beam failure instance counter is implemented in higher layer to control beam recovery, then beam recovery control is improved, but layer interaction complexity increases

Engineering Contradiction:
Improvebeam recovery controlVSAvoidlayer interaction
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces a beam failure instance counter as an intermediary mechanism between the physical layer and higher layers. This counter mediates the beam failure detection process by accumulating failure instances and triggering recovery procedures at appropriate thresholds, thereby simplifying the interaction between layers while maintaining reliable beam recovery control.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The beam failure instance counter performs preliminary counting and evaluation of beam failure instances before triggering the actual beam recovery procedure. By pre-processing the failure detection data and determining when recovery is needed, the system avoids complex real-time decisions during beam failures, simplifying the overall control mechanism.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If beam failure recovery procedure is frequently triggered, then radio link failure prevention is improved, but system throughput decreases

Engineering Contradiction:
Improveradio link failure preventionVSAvoidsystem throughput
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The beam failure instance counter implements a feedback mechanism where beam failure instances are counted and evaluated against configured thresholds before triggering recovery procedures. This feedback-based approach ensures that recovery is only initiated when truly necessary, preventing premature or excessive recovery actions that would degrade system throughput while still maintaining reliable radio link failure prevention.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system changes the parameter of beam failure instance counting from immediate reaction to threshold-based triggering. By accumulating failure instances and only triggering recovery when the counter reaches a configured threshold, the system optimizes the balance between preventing radio link failures and maintaining system throughput, avoiding unnecessary recovery procedures.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3745763B1Transmission of a beam recovery request using a random access preamble responsive to a beam failure instance counter in a higher layer
Publication Date: 2025.07.30 NTT DOCOMO INC
  • EP3745763B1 patent drawingFigure 1
  • EP3745763B1 patent drawingFigure 2
  • EP3745763B1 patent drawingFigure 3

AI summary

The present invention is designed to control recovery from beam failures properly. In accordance with one aspect of the present disclosure, a user terminal has a control section that increments a beam failure instance counter based on a beam failure instance indication received from a physical layer, in a higher layer, and a transmission section that transmits a random access preamble based on a transmission command from the higher layer when the beam failure instance counter reaches or exceeds a given threshold.