HARQ Feedback Control for Sidelink Resources

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Solution Overview

Problem

In NR-V2X systems, it is unclear how to handle HARQ feedback when a Transport Block (TB) is not present in the granted sidelink resource, leading to ambiguity in reporting HARQ-ACK to the base station.

Innovation Solution

A terminal is equipped with a reception unit for receiving downlink control information for sidelink resource allocation, a transmission unit for transmitting data and HARQ responses in the sidelink resource, and a control unit that determines the control related to the HARQ response based on the presence or absence of a TB in the sidelink resource.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the terminal transmits HARQ feedback for granted sidelink resources, then the base station can receive HARQ-ACK information, but it creates ambiguity and control complexity when the transport block is not present

Engineering Contradiction:
ImproveHARQ feedback reliabilityVSAvoidcontrol complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent changes the parameter of HARQ feedback transmission based on the presence or absence of transport block. When no transport block is present, the terminal does not transmit HARQ feedback, thereby avoiding control complexity and ambiguity while maintaining reliable feedback transmission when data is actually transmitted

Inventive Principle:
Principle #35Parameter changes

2Loss of information

If the terminal always reports HARQ-ACK for granted resources, then feedback completeness is improved, but unnecessary reports are generated when no data is transmitted

Engineering Contradiction:
Improvefeedback completenessVSAvoidenergy waste
Core Design Contradiction:
Loss of informationVSLoss of energy

Solution Approach 1:

The patent applies partial action by transmitting HARQ feedback only when necessary (when transport block is present). This avoids the excessive action of reporting HARQ-ACK for granted resources without actual data transmission, thereby preventing energy waste while maintaining feedback completeness for actual data transmissions

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentUS12245245B2Terminal, base station, communication method, and communication system for controlling hybrid automatic repeat request (HARQ) response based on report of HARQ response information
Publication Date: 2025.03.04 NTT DOCOMO INC
  • US12245245B2 patent drawing
  • US12245245B2 patent drawing
  • US12245245B2 patent drawing

AI summary

A terminal includes a reception unit that receives DL (Downlink) control information for allocating a SL (Sidelink) resource, from a base station, a transmission unit that transmits data in the SL resource to another terminal, and transmits a HARQ (Hybrid automatic repeat request) response corresponding to the SL resource or the data to the base station, and a control unit that determines a control related to the HARQ response, based on presence or non-presence of a transport block to be transmitted in the SL resource.