Feedback Retransmission Grants for Unlicensed Spectrum Access

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Solution Overview

Problem

In wireless communication systems operating in unlicensed spectrum, feedback transmissions may be missed due to failed listen-before-talk procedures, leading to inefficiencies and increased latency in retransmissions.

Innovation Solution

A method is introduced where a wireless communication device receives a grant for retransmitting a missed feedback, allowing for an additional opportunity to transmit the feedback, thereby reducing latency and improving spectrum sharing performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a listen-before-talk procedure is used to avoid collisions in unlicensed spectrum, then channel access reliability is improved, but transmission latency increases due to failed procedures

Engineering Contradiction:
Improvechannel access reliabilityVSAvoidtransmission latency
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system performs preliminary actions by sending a grant for feedback transmission before the actual feedback transmission occurs. This grant provides advance instructions including timing and resource allocation, so that when the feedback needs to be retransmitted after a failed LBT, the device can quickly act without additional negotiation delays

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

A grant message serves as an intermediary between the network device and the feedback transmission. The grant carries pre-configured instructions that mediate the interaction, allowing the terminal to autonomously handle retransmission timing and resources without requiring continuous network intervention, thus reducing latency while maintaining reliable access

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If feedback transmission opportunities are provided in unlicensed spectrum, then communication efficiency is improved, but transmission reliability deteriorates due to missed opportunities

Engineering Contradiction:
Improvecommunication efficiencyVSAvoidfeedback transmission reliability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The system provides beforehand cushioning by sending a grant for feedback retransmission in advance, before the actual feedback transmission attempt. This grant acts as a safety cushion that ensures the terminal has pre-configured instructions for retransmission, compensating for potential LBT failures and ensuring feedback reliability without sacrificing communication efficiency

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If multiple grants are communicated for feedback transmission and retransmission, then feedback reliability is improved, but signaling overhead increases

Engineering Contradiction:
Improvefeedback transmission reliabilityVSAvoidsignaling overhead
Core Design Contradiction:
ReliabilityVSLoss of information

Solution Approach 1:

The system merges the feedback transmission grant and retransmission grant into a unified signaling mechanism. The second grant builds upon and extends the first grant, combining multiple functions (initial transmission authorization and retransmission authorization) into a coordinated signaling approach that improves reliability while minimizing redundant information

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP3912293B1Trigger retransmission of a feedback in unlicensed spectrum
Publication Date: 2026.04.22 QUALCOMM INC
  • EP3912293B1 patent drawingFigure 1
  • EP3912293B1 patent drawingFigure 2
  • EP3912293B1 patent drawingFigure 3

AI summary

Wireless communications systems and methods related to providing feedback for DL data are provided. A first wireless communication device communicates with a second wireless communication device, a first communication signal. The first wireless communication device communicates the second wireless communication device, a grant for retransmitting a feedback associated with the first communication signal. The first wireless communication device communicates with the second wireless communication device, the feedback based on the grant.