HARQ-ACK Feedback Timing Across Multi-Carrier NR Scheduling

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

In New Radio (NR) release 17, scheduling multiple carriers with different baseband parameters using a single DCI for PDSCH transmission leads to inconsistent HARQ-ACK feedback due to differing sub-carrier spacings, causing errors in HARQ-ACK transmission when dynamic codebooks are used.

Innovation Solution

Determine a common HARQ-ACK feedback time sequence by referencing the sub-carrier spacing (SCS) or the latest ending position of PDSCHs on multiple carriers, using the PUCCH time unit as a reference for feedback timing, ensuring all carriers transmit HARQ-ACK in the same slot or sub-slot.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the same feedback time sequence (K1) value is used for multiple carriers with different SCS, then DCI overhead is reduced and scheduling efficiency is improved, but HARQ-ACK feedback consistency deteriorates causing transmission errors

Engineering Contradiction:

Improvescheduling efficiencyVSAvoidHARQ-ACK feedback consistency

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies local quality by determining HARQ-ACK feedback time sequences differently for each carrier based on their specific SCS characteristics. Instead of using a uniform feedback time sequence for all carriers, the terminal calculates separate feedback time sequences (K1 values) for each carrier according to their individual sub-carrier spacings, ensuring that each carrier's HARQ-ACK feedback is tailored to its local timing requirements while still being scheduled by a single DCI.

Inventive Principle:

Principle #3Local quality

2Adaptability or versatility

If dynamic HARQ-ACK codebook is used to accommodate different feedback times, then flexibility is improved, but terminal and base station understanding consistency deteriorates due to inconsistent DAI counting

Engineering Contradiction:

Improvefeedback timing flexibilityVSAvoidDAI counting consistency

Core Design Contradiction:

Adaptability or versatilityVSLoss of information

Solution Approach 1:

The patent ensures local quality in DAI counting by having the terminal count Downlink Assignment Indices separately for each carrier based on their respective feedback timing. This carrier-specific DAI counting approach maintains consistency between terminal and base station understanding for each individual carrier, even when feedback occurs at different times, preventing the information loss that would occur with unified counting.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent segments the HARQ-ACK codebook construction process by carrier, with each carrier's feedback being independently tracked and counted. This segmentation allows the dynamic codebook to accommodate different feedback times for different carriers while maintaining consistent understanding through separate DAI counting for each segment (carrier).

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS12500698B2Method and device for determining HARQ-ACK feedback time sequence

Publication Date: 2025.12.16 DATANG MOBILE COMM EQUIP CO LTD

AI summary

A method and a device for determining a HARQ-ACK feedback time sequence are provided. The method includes: receiving first DCI, where the first DCI is used for scheduling PDSCHs transmissions on a plurality of carriers; and determining a time unit for transmitting HARQ-ACKs of the PDSCHs on the plurality of carriers scheduled by the first DCI, according to a reference SCS or the PDSCH with a latest ending position among the PDSCHs on the plurality of carriers scheduled by the first DCI.