Beam Failure Detection Under Full-Duplex Self-Interference

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Solution Overview

Problem

Existing wireless communication systems face challenges in efficiently managing beam failure detection and recovery in full-duplex operations due to self-interference, which affects communication quality and reliability.

Innovation Solution

Implementing beam failure detection (BFD) and beam failure recovery (BFR) mechanisms in full-duplex mode by using BFD reference signals and switching to half-duplex mode when self-interference is detected, along with mechanisms for candidate beam detection and recovery procedures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If beam failure detection is performed during full-duplex operation, then uplink coverage is improved, but self-interference from simultaneous downlink transmission degrades detection accuracy

Engineering Contradiction:
Improvebeam failure detection reliabilityVSAvoidself-interference
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the harmful self-interference component from the received signal by separately receiving downlink reference signals during full-duplex operation. The UE isolates the interference from the gNB's simultaneous downlink transmission and removes it from the uplink signal, enabling clean beam failure detection without contamination from self-interference

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces downlink reference signals as an intermediary element. These reference signals serve as a mediator to characterize and quantify the self-interference channel, allowing the UE to model and compensate for the interference affecting uplink beam failure detection

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If beam failure detection is performed during full-duplex operation, then system resource utilization is improved, but detection accuracy degrades due to self-interference

Engineering Contradiction:
Improvesystem resource utilizationVSAvoidbeam failure detection accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent implements a feedback mechanism where the UE measures downlink reference signals to characterize the self-interference channel, then uses this feedback information to compensate for interference in subsequent uplink beam failure detection. This closed-loop approach maintains detection accuracy while enabling continuous full-duplex operation

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent converts the harmful self-interference into a beneficial measurement opportunity. By intentionally receiving downlink reference signals during full-duplex operation, the UE transforms the interference into useful channel state information that enables accurate beam failure detection through interference characterization and compensation

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

3Loss of information

If downlink reference signals are received during full-duplex operation, then self-interference characterization is improved, but signal processing complexity increases

Engineering Contradiction:
Improveself-interference characterizationVSAvoidsignal processing complexity
Core Design Contradiction:
Loss of informationVSDevice complexity

Solution Approach 1:

The patent performs preliminary characterization of the self-interference channel by receiving and measuring downlink reference signals before they interfere with uplink beam failure detection. This advance preparation allows the UE to pre-compute interference compensation parameters, reducing the processing burden during critical detection moments

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP4327470B1Beam failure detection in full-duplex operation
Publication Date: 2026.05.06 QUALCOMM INC
  • EP4327470B1 patent drawingFigure 1
  • EP4327470B1 patent drawingFigure 2
  • EP4327470B1 patent drawingFigure 3

AI summary

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive, from a base station, a beam failure detection (BFD) reference signal set in one or more slots in a full-duplex mode and in one or more slots in a half-duplex mode. The UE may detect beam failure due to self-interference based at least in part on a comparison of measurements of the BFD reference signal set in the full-duplex mode and half-duplex mode. The UE may switch from the full-duplex mode to the half-duplex mode for slots configured for the full-duplex mode based at least in part on detecting beam failure due to self-interference. Numerous other aspects are described.