UE LBT Failure Reporting via MAC CE and Grant Selection

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Solution Overview

Problem

Uplink resources assigned to a user equipment (UE) for reporting listen-before-talk (LBT) failures in unlicensed spectrum are insufficient to accommodate the necessary information, leading to inefficiencies in failure reporting.

Innovation Solution

The UE employs mechanisms to deliver a medium access control (MAC) control element (CE) indicating uplink LBT failures, such as through random access channel (RACH) procedures, configured grants, or dynamic grants, ensuring adequate resource allocation for failure reporting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If conventional uplink resources are used for reporting LBT failures, then the reporting mechanism is simple, but the resources are insufficient to accommodate the necessary information

Engineering Contradiction:
Improvereporting capacityVSAvoidresource allocation complexity
Core Design Contradiction:
Quantity of substanceVSDevice complexity

Solution Approach 1:

The patent transitions from reporting LBT failures only on the uplink carrier to reporting on both uplink and downlink carriers. This dimensional expansion allows the UE to utilize downlink resources for failure reporting, effectively doubling the available reporting capacity and resolving the resource insufficiency problem.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent enables downlink carriers to serve dual purposes: their original downlink communication function and the additional function of carrying uplink LBT failure reports. This multi-functionality allows existing downlink infrastructure to be repurposed for failure reporting without requiring dedicated new resources.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Loss of information

If uplink resources are increased to accommodate failure information, then reporting completeness improves, but resource allocation complexity increases

Engineering Contradiction:
Improvefailure information completenessVSAvoidresource management complexity
Core Design Contradiction:
Loss of informationVSDevice complexity

Solution Approach 1:

The patent extracts the failure reporting function from the uplink carrier and relocates it to the downlink carrier. This separation allows the uplink resources to be dedicated to data transmission while downlink resources handle both communication and failure reporting, reducing overall resource management complexity.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The downlink carrier acts as an intermediary medium for transmitting uplink failure information. Instead of directly allocating additional uplink resources, the system uses the downlink carrier as a mediator to carry the failure reports, simplifying the resource allocation process.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP4104575B1Reporting uplink listen-before-talk failure
Publication Date: 2026.04.22 APPLE INC
  • EP4104575B1 patent drawingFigure 1
  • EP4104575B1 patent drawingFigure 2
  • EP4104575B1 patent drawingFigure 3

AI summary

The exemplary embodiments relate to a user equipment (UE) delivering an indication of one or more uplink listen-before-talk (LBT) failures to a network. The UE may identify a predetermined condition corresponding to one or more uplink listen-before-talk (LBT) failures associated with a special cell (SpCell). The UE is triggered to provide an indication of uplink LBT failure associated with the SpCell to the network based on the predetermined condition. Next, the UE may determine a type of message that is to be used to deliver the indication of uplink LBT failure associated with the SpCell to the network. The UE may transmit the type of message including the indication of uplink LBT failure associated with the SpCell to the network. Subsequently, the UE may determine that the network received the indication of uplink LBT failure associated with the SpCell.