Semi-Static DL-SPS HARQ Codebooks With ACK/NACK Skipping

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Solution Overview

Problem

Existing HARQ-ACK feedback mechanisms in DL-SPS result in unnecessary transmissions, leading to wastage of UL resources, interference, and energy consumption, especially in unlicensed spectrum where channel access is not guaranteed.

Innovation Solution

Implementing three modes of operation for HARQ-ACK codebook reporting: Mode 1 (no skipping), Mode 2 (skip All-NACK), and Mode 3 (skip All-ACK), allowing the UE to selectively transmit ACK or NACK based on successful PDSCH decoding, and using Type 3 one-shot feedback for a subset of HARQ processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If HARQ-ACK feedback is transmitted for every scheduled transmission in DL-SPS, then reliability of acknowledgment is improved, but UL resource wastage and interference increase

Engineering Contradiction:

ImproveHARQ-ACK feedback reliabilityVSAvoidUL resource wastage

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies partial action by transmitting HARQ-ACK feedback only when necessary (when ACK is present or when configured to transmit all feedback). The UE selectively transmits feedback based on the content of the codebook and configuration, avoiding unnecessary transmissions of all-NACK codebooks while maintaining reliability for actual data transmissions.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The patent introduces dynamic behavior by allowing the gNB to configure different feedback transmission modes via RRC signaling. The UE can switch between transmitting all feedback, transmitting only when ACK is present, or other modes based on network configuration, making the system adaptable to different channel conditions and traffic patterns.

Inventive Principle:

Principle #15Dynamics

2Loss of information

If HARQ-ACK feedback is transmitted for every scheduled transmission in DL-SPS, then completeness of feedback information is improved, but interference to other UEs increases

Engineering Contradiction:

Improvefeedback information completenessVSAvoidUL interference

Core Design Contradiction:

Loss of informationVSObject-generated harmful factors

Solution Approach 1:

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The patent applies local quality by allowing different UEs to have different feedback transmission behaviors based on their specific configurations and channel conditions. Each UE's feedback transmission is optimized locally rather than applying a uniform approach to all UEs, reducing overall interference while maintaining individual reliability.

Inventive Principle:

Principle #3Local quality

3Measurement precision

If HARQ-ACK feedback is transmitted for every scheduled transmission in DL-SPS, then accuracy of transmission status reporting is improved, but energy consumption increases

Engineering Contradiction:

Improvetransmission status reporting accuracyVSAvoidUE energy consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The patent changes the parameter of feedback transmission behavior based on configuration mode. The UE can operate in different modes (transmit all feedback, transmit only when ACK present, etc.) which are parameter changes in the feedback transmission strategy, optimizing energy consumption while maintaining necessary reporting accuracy.

Inventive Principle:

Principle #35Parameter changes

4Reliability

If semi-static codebook size is fixed to cover all possible transmissions, then robustness against missed assignments is improved, but codebook size becomes excessively large

Engineering Contradiction:

Improverobustness against missed assignmentsVSAvoidcodebook size

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent applies partial action by only transmitting feedback for actually received transmissions when configured to do so. Instead of always transmitting a large fixed-size codebook, the UE can transmit a reduced codebook containing only relevant ACK/NACK information, reducing the quantity of transmitted bits while maintaining robustness through selective feedback.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The patent introduces dynamic codebook size adjustment based on the number of actually received transmissions. The codebook size becomes dynamic rather than fixed, adapting to the actual transmission pattern while maintaining the robustness benefit of semi-static configuration for the configured set of transmissions.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS12418365B2Semi-static HARQ codebook for DL-SPS

Publication Date: 2025.09.16 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

A method and communication device for reporting HARQ-ACK code books of fixed sizes in a communication network is provided. The method includes responsive to operating in a first mode, reporting the HARQ-ACK codebook for each scheduled transmission to a network node. The method further includes responsive to operating in a second mode, reporting the HARQ-ACK codebook to the network node if at least one of the HARQ-ACK information in the codebook is ACK, wherein no NACK is transmitted in the codebook when operating in the second mode. The method further includes responsive to operating in a third mode, reporting the HARQ-ACK codebook to the network node if at least one of the HARQ-ACK information in the codebook is NACK, wherein no ACK is transmitted in the codebook when operating in the second mode.