Sidelink Retransmission Feedback Timing for Half-Duplex Conflict Avoidance

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Solution Overview

Problem

Current wireless communication technologies lack an effective feedback retransmission mechanism for sidelink communication in half-duplex scenarios, leading to conflicts and errors in data transmission due to half-duplex interference, particularly in vehicle-to-everything (V2x) communication.

Innovation Solution

A retransmission feedback method for sidelink communication that involves generating and sending feedback information for each retransmission, using a pre-configured or configured feedback time interval, to avoid conflicts and improve data reception success rates in half-duplex operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a new DCI format is designed to support both downlink and uplink retransmission scheduling, then scheduling flexibility is improved, but control signal overhead and processing complexity increase

Engineering Contradiction:
Improvescheduling flexibilityVSAvoidcontrol signal processing complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent segments the retransmission scheduling function into separate downlink and uplink processes. Downlink retransmissions are scheduled using PDCCH indications, while uplink retransmissions are scheduled using PUCCH feedback and subsequent PDCCH grants. This segmentation avoids the need for a complex unified DCI format while maintaining scheduling flexibility for both directions independently.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of using a new DCI format to schedule both downlink and uplink retransmissions directly, the patent inverts the approach by using PUCCH feedback to trigger uplink retransmission scheduling. The network first receives HARQ-ACK feedback on PUCCH, then sends separate PDCCH downlink control information to schedule the uplink retransmission, thereby avoiding complex DCI formatting while achieving bidirectional scheduling capability.

Inventive Principle:
Principle #13The other way round (Inversion)

2Device complexity

If PUCCH resource allocation is restricted to specific slots, then resource management is simplified, but scheduling flexibility and user experience deteriorate

Engineering Contradiction:
ImprovePUCCH resource management complexityVSAvoidscheduling flexibility
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent implements dynamic PUCCH resource allocation where the network can flexibly assign PUCCH resources in different slots based on traffic conditions and user needs. The terminal receives dynamic indications from the network about which slots to use for PUCCH feedback, allowing the system to adapt to varying scheduling requirements while maintaining manageable resource allocation through centralized network control.

Inventive Principle:
Principle #15Dynamics

3Adaptability or versatility

If PUCCH feedback is delayed to enable network scheduling of uplink retransmission, then scheduling control is improved, but feedback timeliness and user experience deteriorate

Engineering Contradiction:
Improvescheduling control capabilityVSAvoidfeedback delay
Core Design Contradiction:
Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent employs preliminary action by having the terminal prepare and send PUCCH feedback in advance at the first available opportunity after receiving the downlink transmission. Instead of waiting for network scheduling decisions, the terminal proactively provides HARQ-ACK feedback on PUCCH, which then triggers the network to send uplink retransmission scheduling grants. This preliminary feedback action reduces overall delay while maintaining network scheduling control.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3955601B1Method and device for retransmitting feedback for direct-connection communication, and storage medium
Publication Date: 2026.04.29 BEIJING XIAOMI MOBILE SOFTWARE CO LTD
  • EP3955601B1 patent drawingFigure 1~2
  • EP3955601B1 patent drawingFigure 3~4
  • EP3955601B1 patent drawingFigure 5~6

AI summary

The present disclosure relates to a method and device for retransmitting a feedback for direct-connection communication and related to the technical field of communications. The method is executed by a first terminal. The method comprises: during a process of retransmitting direct-connection data with a second terminal, generating feedback information for each instance of retransmission in retransmissions, the feedback information being used for indicating whether the direct-connection data is correctly received, the retransmissions comprising at least one retransmission; acquiring a feedback resource for each instance of retransmission in the retransmissions; and, on the feedback resource for each instance of retransmission, transmitting feedback information of each instance of retransmission to the second terminal. The present disclosure, when terminals are directly communicating with each other, with a first terminal performing a feedback with respect to the direct-connection data of each instance of retransmission of the second terminal, prevents the problem of a conflict occurring between the feedback information and other information when transmitting data with other devices in a half-duplex state, and increases the success rate of feedback with respect to retransmitted data between the terminals.