Multi-Cell HARQ Codebook Ordering with Single-DCI Scheduling

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Solution Overview

Problem

Existing HARQ feedback mechanisms in carrier aggregation systems with a single DCI scheduling multiple cells result in incorrect HARQ feedback indication sizes and ordering due to missed DCIs, leading to inefficiencies and increased DCI overhead.

Innovation Solution

Implement a single DCI that schedules PDSCHs on multiple cells, using a counter DAI that is independent of the number of scheduled cells and adjusts the entry size of the HARQ feedback indication based on the number of scheduled cells, along with a pre-defined order for inserting HARQ feedback bits in the HARQ codebook.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single DCI schedules PDSCHs on multiple cells, then DCI overhead is reduced, but HARQ feedback indication size and ordering become incorrect due to missed DCIs

Engineering Contradiction:

ImproveDCI overheadVSAvoidHARQ feedback indication size and ordering accuracy

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent modifies the counter DAI parameter to be independent of the number of scheduled cells, and introduces a total DAI parameter that counts the total number of scheduled cells across all DCIs. This parameter change enables correct HARQ feedback indication size and ordering while maintaining the benefit of reduced DCI overhead from single DCI multi-cell scheduling.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements feedback mechanisms using DAIs (Downlink Assignment Indicators) in DCIs to provide information about the number and ordering of scheduled cells. The UE uses this feedback information to correctly construct HARQ feedback indications, ensuring accurate sizing and ordering even when DCIs are missed.

Inventive Principle:

Principle #23Feedback

2Manufacturing precision

If counter DAI is incremented for each scheduled cell, then HARQ feedback ordering is maintained, but DCI size increases

Engineering Contradiction:

ImproveHARQ feedback ordering accuracyVSAvoidDCI size

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent segments the DAI counting into two independent parts: counter DAI that tracks the current DCI position (independent of cell count) and total DAI that counts total scheduled cells. This segmentation allows maintaining ordering accuracy without increasing DCI size, as counter DAI can use a fixed number of bits.

Inventive Principle:

Principle #1Segmentation

3Reliability

If HARQ codebook size is based on configured cells, then all cells are covered, but unnecessary large size occurs when few cells are scheduled

Engineering Contradiction:

ImproveHARQ feedback completenessVSAvoidHARQ codebook size

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent makes the HARQ codebook size dynamic by using total DAI to indicate the actual number of scheduled cells. Instead of a fixed size based on configured cells, the codebook size adapts to the actual scheduling situation, reducing unnecessary overhead when fewer cells are scheduled while maintaining completeness when all cells are scheduled.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS12500703B2DAI and HARQ codebook for multi-cell scheduling

Publication Date: 2025.12.16 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

The present invention relates to the field of communication technology with regard to cell scheduling. A method of operating a network node comprises transmitting a single Downlink Control Information (DCI) to a radio node, the single DCI scheduling Physical Downlink Shared Channels (PDSCHs) on a plurality of cells. The single DCI indicates a counter downlink assignment indicator (DAI) which is either based on the plurality of scheduled cells or independent of the plurality of cells scheduled by the single DCI.