Compacting HARQ Feedback Bits in Wireless Uplink Control

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Solution Overview

Problem

The existing HARQ feedback mechanisms in wireless communication systems face inefficiencies due to the need to reserve resources for each configured carrier in carrier aggregation scenarios, leading to unendurable overhead, especially when dealing with a large number of unlicensed carriers and sparse scheduling, which limits the capacity of uplink control channels.

Innovation Solution

The method involves providing User Equipment (UE) with assisting information such as Downlink Assignment Index (DAI) or scheduling indicators to determine the number and order of HARQ ACK bits, allowing for compact HARQ feedback transmission by reducing or eliminating padding bits, thereby optimizing radio resource consumption and channel usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If resources are reserved for each configured carrier in carrier aggregation scenarios, then HARQ feedback can be transmitted for all carriers, but uplink control channel capacity is exceeded and overhead becomes unendurable

Engineering Contradiction:

ImproveHARQ feedback transmissionVSAvoiduplink control channel capacity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the HARQ feedback transmission by dividing it into multiple parts: actual data carriers and virtual carriers. Only carriers with actual downlink data assignments are included in the HARQ feedback, while carriers without data are excluded. This segmentation reduces the total number of HARQ bits needed while maintaining reliable feedback for all active carriers.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent extracts and removes the unnecessary padding bits corresponding to virtual carriers (carriers without actual downlink data) from the HARQ feedback transmission. By taking out these redundant elements, the overhead is significantly reduced while the essential HARQ feedback information for actual data carriers is preserved.

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If padding bits are included for all configured carriers, then complete HARQ coverage is maintained, but radio resource consumption increases

Engineering Contradiction:

ImproveHARQ feedback coverageVSAvoidtransmission power

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent dynamically changes the parameter of HARQ feedback size based on the actual number of downlink data carriers. Instead of using a fixed size for all configured carriers, the feedback size adapts to the actual traffic conditions, reducing transmission power when fewer carriers have data while maintaining complete coverage when all carriers are active.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If resources are allocated for maximum HARQ bits, then all scheduling scenarios are supported, but channel capacity is wasted during sparse scheduling

Engineering Contradiction:

Improvescheduling scenario supportVSAvoidchannel capacity utilization

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent introduces dynamic HARQ feedback size adjustment based on the actual number of downlink data carriers. The feedback size is not fixed but adapts dynamically to the scheduling scenario, being large when many carriers have data and small when few carriers have data, thus optimizing channel capacity utilization while supporting all scheduling scenarios.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

Inventive Principle:

Principle #35Parameter changes

4Quantity of substance

If uplink control channel resources are increased, then more HARQ bits can be transmitted, but system complexity and resource overhead increase

Engineering Contradiction:

ImproveHARQ feedback bitsVSAvoidcontrol channel resource management

Core Design Contradiction:

Quantity of substanceVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent creates a universal HARQ feedback mechanism that works for both dense and sparse scheduling scenarios by using a dynamic size adjustment approach. The same feedback structure adapts to different carrier aggregation configurations and scheduling densities, eliminating the need for separate resource allocations for different scenarios.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentEP3281332B1Method and user equipment for compacting HARQ feedback

Publication Date: 2022.10.05 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

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AI summary

The present disclosure provides a method for operating in a User Equipment (UE) for compacting HARQ feedback transmission in uplink in a wireless communication system. The method comprises: receiving, from a radio network node, an assisting information indicating arrangement of scheduled downlink transmissions; determining, based on the assisting information, number and order of the HARQ feedback bits; and transmitting, to the radio network node, the HARQ feedback in a compacted manner of reduced padding bits based on the number and order of the HARQ feedback bits.