LBT Failure Reporting via MAC CE for Uplink Reliability

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Solution Overview

Problem

In a 5G mobile communications system, terminals face a low success rate for uplink sending due to Listen-Before-Talk (LBT) failures when attempting to use unlicensed bands, as there is no existing method for effectively notifying network side devices of LBT failures.

Innovation Solution

The method involves using a Medium Access Control (MAC) Control Element (CE) to send LBT failure information from the terminal to the network side device, allowing the network to instruct the terminal to change its operating frequency and perform LBT again, thereby increasing the success rate of uplink sending.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the terminal uses unlicensed band for uplink sending, then the available spectrum resource is increased, but the LBT failure rate increases causing low uplink sending success rate

Engineering Contradiction:

Improvespectrum resourceVSAvoiduplink sending success rate

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The terminal changes the operating frequency parameter when LBT failure is detected. Instead of persisting on the blocked frequency, the terminal switches to a different frequency within the unlicensed band, thereby maintaining spectrum utilization while overcoming the LBT failure condition and improving uplink sending success rate.

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If the terminal performs LBT before sending on unlicensed band, then the interference to other systems is reduced, but the uplink sending delay increases due to LBT failure

Engineering Contradiction:

Improveinterference to other systemsVSAvoiduplink sending delay

Core Design Contradiction:

Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The terminal performs LBT in advance before uplink sending on the unlicensed band. By conducting the listen-before-talk check beforehand, the terminal can detect channel occupancy early and proactively switch frequencies if needed, preventing transmission delays that would occur if LBT were performed later in the process.

Inventive Principle:

Principle #10Preliminary action

3Ease of operation

If the terminal continuously retries LBT on the same frequency, then the simplicity of operation is maintained, but the uplink sending success rate remains low

Engineering Contradiction:

Improveoperation simplicityVSAvoiduplink sending success rate

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The terminal dynamically adjusts its operating frequency based on LBT results. When LBT failure is detected, the terminal automatically switches to a different frequency rather than statically persisting on the original frequency. This dynamic adaptation maintains operational simplicity from the terminal's perspective while significantly improving uplink sending success rate.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS12309834B2Listen-before-talk failure processing method, terminal, and network side device

Publication Date: 2025.05.20 VIVO MOBILE COMM CO LTD

AI summary

The present disclosure provides a listen-before-talk (LBT) failure processing method, a terminal, and a network side device. The LBT failure processing method can be performed by the terminal. The method includes sending LBT failure information by using a medium access control (MAC) control element (CE) in a case of an LBT failure. The present disclosure limits a manner of reporting LBT failure information.