Unified HARQ-ACK Codebook for DL and Sidelink Feedback

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Solution Overview

Problem

Existing sidelink communication systems face inefficiencies in transmitting and receiving hybrid automatic repeat request (HARQ) responses, particularly in unicast schemes, which affect the performance of Vehicle-to-Everything (V2X) communications.

Innovation Solution

The terminal generates an HARQ-ACK codebook that includes both DL HARQ information bits and SL HARQ information bits, ensuring the same type of codebook is used for both, facilitating efficient transmission and improving communication system performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If separate codebooks are used for DL HARQ and SL HARQ responses, then the transmission protocol can be simple and easy to implement, but the transmission efficiency is reduced and communication performance deteriorates

Engineering Contradiction:
ImproveHARQ response transmission efficiencyVSAvoidcodebook management complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent merges DL HARQ and SL HARQ responses into a single unified HARQ-ACK codebook structure. The terminal device generates one codebook that contains both downlink and sidelink HARQ acknowledgment bits, eliminating the need for separate codebook generation and transmission procedures. This consolidation directly improves transmission efficiency by reducing signaling overhead and processing complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The unified HARQ-ACK codebook serves multiple functions simultaneously: it carries both DL HARQ feedback and SL HARQ feedback, and supports multiple codebook types (semi-static and dynamic) within a single structure. This multi-functional design allows the system to maintain flexibility while improving overall transmission efficiency.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Productivity

If unified HARQ-ACK codebook is used for both DL and SL HARQ responses, then transmission efficiency is improved, but the complexity of codebook generation and management increases

Engineering Contradiction:
Improvecommunication system performanceVSAvoidcodebook generation complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The unified HARQ-ACK codebook is segmented into distinct bit fields: DL HARQ information bits and SL HARQ information bits. Each segment follows its own formatting rules and can be independently configured. This segmentation allows the terminal to generate the unified codebook in an organized manner, reducing the perceived complexity while maintaining the benefits of unification.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic codebook generation where the terminal can adaptively select between semi-static and dynamic codebook types based on scheduling conditions. The codebook structure dynamically adjusts to include only the necessary HARQ bits for the current transmission scenario, reducing unnecessary processing complexity while maintaining high transmission efficiency.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP4044479B1Method and device for transmitting and receiving HARQ response in communication system
Publication Date: 2026.02.18 HYUNDAI MOTOR CO LTD
  • EP4044479B1 patent drawingFigure 1
  • EP4044479B1 patent drawingFigure 2
  • EP4044479B1 patent drawingFigure 3~4

AI summary

Disclosed are a method and a device for transmitting and receiving a HARQ response in a communication system. An operating method for a first terminal comprises the steps of: receiving, from a base station, setting information comprising a first information element for indicating the type of a HARQ-ACK codebook; generating the HARQ-ACK codebook comprising a DL HARQ information bit about downlink communication between the base station and the first terminal, and an SL HARQ information bit about sidelink communication between the first terminal and a second terminal; and transmitting the HARQ-ACK codebook to the base station by using an uplink channel.