Trigger Flag in Downlink Assignment for Aperiodic CSI Feedback

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Solution Overview

Problem

In LTE systems, the reliance on aperiodic CSI feedback for downlink scheduling leads to increased PDCCH overhead, especially when there is no uplink data scheduling, resulting in inefficient use of system resources.

Innovation Solution

Incorporating a trigger flag in the downlink assignment to indicate the need for aperiodic CSI feedback, allowing the user equipment to determine and send the CSI on specific uplink resources, thereby reducing control channel overhead and improving resource utilization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If aperiodic CSI feedback is triggered through uplink grants, then channel state information can be obtained for downlink scheduling, but control channel overhead increases due to many uplink grants scheduling only CSI

Engineering Contradiction:

Improvechannel state information feedbackVSAvoidPDCCH overhead

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent combines the CSI trigger function with the downlink assignment message, merging two separate control functions (downlink scheduling and CSI triggering) into a single message. This eliminates the need for separate uplink grants to trigger aperiodic CSI, thereby reducing PDCCH overhead while maintaining reliable channel state information feedback.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The downlink assignment message is enhanced to serve multiple functions: it not only schedules downlink data transmission but also triggers aperiodic CSI feedback when the trigger flag is set. This multi-functionality reduces the need for dedicated uplink grants, decreasing control channel overhead while ensuring reliable CSI acquisition.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If uplink grants are sent to trigger aperiodic CSI feedback, then channel state information can be collected, but system resources are inefficiently utilized when no uplink data scheduling is needed

Engineering Contradiction:

Improveaperiodic CSI feedbackVSAvoidsystem resource utilization

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent merges the CSI trigger function into the downlink assignment message, eliminating the need for separate uplink grants. This combination ensures that CSI feedback is triggered only when downlink scheduling occurs, improving system resource utilization while maintaining reliable aperiodic CSI feedback collection.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The downlink assignment message itself serves the dual purpose of scheduling downlink data and triggering CSI feedback. This self-service approach eliminates the need for additional uplink grants, improving resource efficiency while ensuring that channel state information is collected when needed.

Inventive Principle:

Principle #25Self-service

3Quantity of substance

If downlink assignment includes trigger flag for aperiodic CSI, then control channel overhead is reduced, but the downlink assignment structure becomes more complex

Engineering Contradiction:

Improvecontrol channel overheadVSAvoiddownlink assignment structure

Core Design Contradiction:

Quantity of substanceVSDevice complexity

Solution Approach 1:

The patent introduces a trigger flag parameter in the downlink assignment message to control aperiodic CSI feedback. This parameter addition increases the message structure complexity slightly but eliminates the need for separate uplink grants, resulting in a net reduction of control channel overhead and improved resource efficiency.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11283541B2Method, user equipment, and base station for transmitting information

Publication Date: 2022.03.22 HUAWEI TECH CO LTD

AI summary

A method for transmitting information, the method including receiving a downlink assignment sent by a base station, where the downlink assignment comprises a trigger flag, and where the trigger flag indicates a trigger state of aperiodic channel state information (CSI), determining an uplink resource used to send the aperiodic CSI according to an uplink resource indication information, and sending, on the uplink resource, the aperiodic CSI to the base station according to the trigger flag.