Unlicensed-Band Beam Failure Recovery with Shared COT Access

Solution Overview

Problem

Beam failure recovery (BFR) procedures on unlicensed frequency bands in NR-U systems incur significant latency due to the need for channel idle detection mechanisms like LBT, which increases the overall latency of the BFR process.

Innovation Solution

The proposed solution involves reducing latency by allowing user equipment (UE) to share the channel occupancy time (COT) of downlink transmissions from the base station and dynamically adjusting the size of the contention window during LBT, thereby minimizing the need for channel idle detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If channel idle detection (LBT) is performed before uplink transmission in beam failure recovery, then collision avoidance is ensured, but transmission latency increases significantly

Engineering Contradiction:

Improvecollision avoidanceVSAvoidbeam failure recovery latency

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The base station performs channel idle detection in advance during downlink transmission and shares the detected idle period with the UE. This preliminary action allows the UE to skip redundant LBT procedures, ensuring collision avoidance while significantly reducing beam failure recovery latency.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The base station acts as an intermediary by sharing its channel occupancy time information with the UE. This intermediary mechanism allows the UE to utilize the base station's previously detected idle channel period, eliminating the need for the UE to perform full LBT and thus reducing latency while maintaining collision avoidance.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If full channel idle detection is performed by user equipment, then channel access safety is ensured, but beam failure recovery speed decreases

Engineering Contradiction:

Improvechannel access safetyVSAvoidbeam failure recovery speed

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The base station performs channel idle detection in advance during downlink transmission and shares the detected idle period with the UE. This preliminary action allows the UE to skip redundant LBT procedures, ensuring collision avoidance while significantly reducing beam failure recovery latency.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent applies different channel access requirements to different transmission scenarios. For beam failure recovery, the UE uses a simplified approach leveraging the base station's previous channel assessment, while maintaining safety through the base station's coordination. This local quality differentiation optimizes speed without compromising safety.

Inventive Principle:

Principle #3Local quality

3Adaptability or versatility

If user equipment performs independent channel idle detection, then channel access independence is maintained, but system complexity increases

Engineering Contradiction:

Improvechannel access independenceVSAvoidbeam failure recovery procedure complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The base station acts as an intermediary by sharing its channel occupancy time information with the UE. This intermediary mechanism allows the UE to utilize the base station's previously detected idle channel period, eliminating the need for the UE to perform full LBT and thus reducing latency while maintaining collision avoidance.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system dynamically adapts the channel access procedure based on the transmission scenario. During beam failure recovery, the UE transitions from performing full independent LBT to a simplified approach where it leverages the base station's channel assessment, reducing procedural complexity while maintaining adaptability.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS12418810B2Electronic device and method for wireless communication, and computer readable storage medium

Publication Date: 2025.09.16 SONY GROUP CORP

AI summary

The present disclosure provides an electronic device and a method for wireless communication, and a computer readable storage medium. The electronic device comprises: a processing circuit configured to determine that a beam failure event occurs on a downlink of an unlicensed band, and to execute, on the unlicensed band and in a beam failure recovery process for the beam failure event, delay reduced clear channel assessment-based uplink transmission.