HARQ Feedback Transmission for Direct Communication

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Solution Overview

Problem

In V2X communication technologies, the existing blind retransmission mechanisms for HARQ feedback information can lead to collisions due to half-duplex conditions, resulting in unreliable data transmission and wastage of network resources.

Innovation Solution

A method where the first terminal transmits HARQ feedback information after the second terminal's last blind retransmission, and if the second terminal does not receive this feedback, the first terminal retransmits it using a second blind retransmission mechanism, ensuring that the feedback is received even in half-duplex conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the first terminal transmits HARQ feedback information after the second terminal's last blind retransmission, then the reliability of feedback information transmission is improved, but the complexity of the retransmission mechanism increases

Engineering Contradiction:
Improvereliability of HARQ feedback information transmissionVSAvoidcomplexity of retransmission mechanism
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by having the first terminal determine in advance whether the second terminal has correctly received direct data before initiating HARQ feedback transmission. The terminal also pre-configures blind retransmission parameters (number of retransmissions, time intervals) before actual transmission occurs, allowing the system to prepare for potential feedback failures without adding real-time complexity

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements a feedback mechanism where the first terminal transmits HARQ feedback information to indicate whether direct data was correctly received. When the feedback transmission fails (detected through blind retransmission counter), the system triggers another round of feedback transmission, creating a closed-loop feedback system that ensures reliable information delivery without requiring complex real-time decision-making

Inventive Principle:
Principle #23Feedback

2Loss of energy

If the first terminal retransmits HARQ feedback information with the second blind retransmission mechanism, then the network resources are conserved by preventing unnecessary direct data retransmissions, but the time for feedback transmission increases

Engineering Contradiction:
Improvenetwork resource wastageVSAvoidtime for feedback transmission
Core Design Contradiction:
Loss of energyVSLoss of time

Solution Approach 1:

The patent applies periodic action through blind retransmission mechanisms where the first terminal retransmits HARQ feedback information at predetermined time intervals. The system configures a maximum number of blind retransmissions and time intervals in advance, creating a periodic transmission pattern that ensures feedback delivery without requiring continuous monitoring or complex scheduling decisions

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system performs preliminary configuration of blind retransmission parameters (number of attempts, time intervals) before actual feedback transmission. This allows the system to establish a predetermined retry strategy that balances resource conservation with time efficiency, avoiding both excessive retries and premature abandonment of feedback transmission

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3955604B1Method, device, equipment, and system for feedback information transmission for direct communication
Publication Date: 2025.06.18 BEIJING XIAOMI MOBILE SOFTWARE CO LTD
  • EP3955604B1 patent drawingFigure 1~2
  • EP3955604B1 patent drawingFigure 3~4
  • EP3955604B1 patent drawingFigure 5~6

AI summary

The present disclosure relates to a method, device, equipment, and system for feedback information transmission for direct communication and relates to the technical field of communications. The method comprises: when a first terminal determines that a second terminal transmits direct-connection data to the first terminal with a first blind retransmission mechanism for the last time, the first terminal transmits hybrid automatic repeat request (HARQ) feedback information to the second terminal, the HARQ feedback information is used for indicating a receive state of the direct-connection data when a blind transmission is completed; and, the first terminal retransmits the HARQ feedback information to the second terminal with a second blind retransmission mechanism. The present disclosure increases the reliability of HARQ feedback information transmission and saves network resources.