Sidelink Block ACK Handling for Low-Latency Unlicensed Spectrum

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Solution Overview

Problem

The increasing demand for mobile broadband communication and the need for enhanced reliability and low latency in wireless communication systems, particularly in sidelink communication between UEs, is not adequately addressed by existing Radio Access Technologies (RATs, especially in scenarios involving vehicle-to-everything (V2X) communication.

Innovation Solution

Implementing a method and device for wireless communication that includes obtaining and transmitting block acknowledgement (ACK) information related to hybrid automatic repeat request (HARQ) feedbacks and sidelink HARQ process identifiers, enabling efficient data transmission and reception between devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional HARQ feedback methods are used in sidelink communication, then each data transmission requires separate acknowledgment, but this increases communication overhead and latency

Engineering Contradiction:
ImprovereliabilityVSAvoidlatency
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent combines multiple individual HARQ feedback messages into a single block acknowledgment message. The transmitting UE sends multiple data transmissions, and the receiving UE responds with one consolidated block ACK that contains acknowledgment information for all received data packets, rather than sending separate ACK/NACK messages for each packet. This merging approach reduces the total number of messages exchanged, thereby reducing communication overhead and latency while maintaining reliable data transmission.

Inventive Principle:
Principle #5Merging (Combining)

2Reliability

If multiple individual HARQ feedback messages are transmitted, then each data packet is acknowledged separately, but this increases communication overhead

Engineering Contradiction:
ImprovereliabilityVSAvoidcommunication overhead
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges multiple individual HARQ feedback messages into a single block acknowledgment message. The receiving UE generates one consolidated block ACK message that contains acknowledgment information for multiple received data packets, identifying which packets were successfully received and which require retransmission. This approach significantly reduces the number of separate control messages that need to be transmitted and processed, thereby reducing communication overhead and simplifying the feedback mechanism while maintaining reliable data transmission.

Inventive Principle:
Principle #5Merging (Combining)

3Loss of information

If separate acknowledgment messages are sent for each data transmission, then feedback accuracy is maintained, but communication efficiency decreases

Engineering Contradiction:
Improvefeedback accuracyVSAvoidcommunication efficiency
Core Design Contradiction:
Loss of informationVSProductivity

Solution Approach 1:

The patent combines multiple acknowledgment responses into a single block ACK message that preserves feedback accuracy. The block ACK includes specific information about each data packet's reception status, allowing the transmitting UE to identify exactly which packets were successfully received and which need retransmission. This merging approach maintains the precision of individual packet acknowledgment while improving communication efficiency by reducing the total number of messages exchanged and the time required for the feedback process.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP4648323A1Method and device for performing sidelink communication in unlicensed spectrum
Publication Date: 2025.11.12 LG ELECTRONICS INC
  • EP4648323A1 patent drawingFigure 1
  • EP4648323A1 patent drawingFigure 2
  • EP4648323A1 patent drawingFigure 3

AI summary

Provided are a method performed by a first device and a device supporting same in a wireless communication system. The method may comprise the steps of: acquiring information related to block acknowledgement (ACK); receiving, from a second device, control information including information for transmitting a plurality of pieces of hybrid acknowledgement repeat request (HARQ) feedback to the block ACK, and information for transmitting each sidelink (SL) HARQ process identifier (ID) related to the plurality of pieces of HARQ feedback; receiving a plurality of pieces of data related to the block ACK from the second device on the basis of the control information; and transmitting the block ACK to the second device in response to the reception of the plurality of pieces of data related to the block ACK.