Multi-TRP HARQ Feedback Using Shared PUCCH Resources

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Solution Overview

Problem

Existing methods for multi-TRP (Transmission Reception Point) communication in 5G NR systems face challenges in efficiently managing HARQ ACK/NACK feedback, particularly in scenarios with non-ideal backhaul, leading to increased PUCCH overhead and inefficient resource utilization.

Innovation Solution

Implementing methods for assigning downlink control channel candidates and managing HARQ feedback by implicitly linking CORESET groups to TRPs, allowing transparent PUCCH resource sharing and joint or separate HARQ feedback based on backhaul conditions, using explicit or implicit CORESET group configurations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If separate PUCCH resources are allocated for each TRP in multi-TRP scenarios, then HARQ feedback reliability is improved, but PUCCH overhead and resource utilization efficiency deteriorate

Engineering Contradiction:

ImproveHARQ feedback reliabilityVSAvoidPUCCH overhead

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent combines multiple PUCCH resources from different TRPs into a single shared resource pool. The network configures multiple PUCCH resources but allows UEs to select and share them across multiple TRPs, thereby reducing total PUCCH overhead while maintaining feedback reliability through diverse resource selection.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

PUCCH resources are designed to serve multiple TRPs simultaneously rather than being dedicated to single TRPs. Each PUCCH resource can be utilized by UEs receiving services from any of the configured TRPs, enabling universal resource usage and improving overall system efficiency.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If multiple PUCCH resources are configured for multi-TRP scenarios, then HARQ feedback capability is improved, but resource utilization efficiency deteriorates

Engineering Contradiction:

ImproveHARQ feedback capabilityVSAvoidresource utilization efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent implements dynamic PUCCH resource selection where UEs can adaptively choose from multiple configured resources based on current channel conditions and TRP status. This dynamic approach ensures high feedback capability while optimizing resource utilization by activating only necessary resources.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The network pre-configures multiple PUCCH resources in advance, but they remain inactive until needed. When multi-TRP operation is required, the system activates appropriate resources from the pre-configured pool, ensuring immediate feedback capability while maintaining efficient resource utilization by keeping unused resources dormant.

Inventive Principle:

Principle #10Preliminary action

3Device complexity

If implicit CORESET group linking is implemented, then system complexity is reduced, but adaptability to different backhaul conditions deteriorates

Engineering Contradiction:

Improvesystem complexityVSAvoidadaptability to backhaul conditions

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent segments CORESET groups into different categories (e.g., first CORESET group for ideal backhaul, second CORESET group for non-ideal backhaul) with implicit linking to specific PUCCH resource sets. This segmentation reduces complexity by providing default mappings while maintaining adaptability through configuration options that allow switching between different groupings based on backhaul conditions.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentEP3925124B1HARQ ACK for multi-pdcch scheduled pdsch transmission over multiple transmission reception points

Publication Date: 2025.07.02 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

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Figure 4~5(b)

AI summary

A method and apparatus are disclosed. In one embodiment, a method in a wireless device (WD) includes receiving: a physical downlink control channel, PDCCH, configuration of a first group of one or more first control resource sets, CORESETs, having a first group index and a second group of one or more CORESETs having a second group index; and a physical uplink control channel, PUCCH, configuration of a plurality number of PUCCH resource sets, each PUCCH resource set including a plurality number of PUCCH resources; monitoring a first PDCCH in the first group and a second PDCCH in the second group; receiving a first physical downlink shared channel, PDSCH, scheduled by the first PDCCH and a second PDSCH scheduled by the second PDCCH; and transmitting a first Hybrid Automatic Repeat reQuest, HARQ, acknowledgement/non-acknowledgement, A/N, associated with the first PDSCH and a second HARQ A/N associated with the second PDSCH.