Sub-band CSI Reporting for URLLC via ACK/NACK Feedback

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Solution Overview

Problem

In ultra-reliable low latency communications (URLLC), existing systems face challenges in efficiently reporting sub-band channel state information (CSI) due to interference, which affects the quality of service and reliability, particularly when the user equipment (UE) transmits an acknowledgement (ACK) or negative acknowledgement (NACK) in response to physical downlink shared channel (PDSCH) transmissions.

Innovation Solution

The method involves determining whether to transmit a sub-band CSI report to the base station based on the ACK or NACK transmission, with the option to include full resolution or reduced resolution channel quality information, depending on the decoding ability and interference levels, to optimize payload efficiency and information accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If full resolution sub-band CSI reports are transmitted, then channel state information accuracy is improved, but uplink payload size increases

Engineering Contradiction:

Improvechannel state information accuracyVSAvoiduplink payload size

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent implements dynamic adjustment of CSI report resolution based on transmission conditions. The UE determines whether to report full resolution or reduced resolution CSI information based on ACK/NACK feedback from previous transmissions, making the reporting granularity adaptive to current channel conditions and reliability requirements

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the resolution parameter of CSI reports dynamically. When ACK is received indicating good channel conditions, the UE reduces CSI report resolution to save uplink resources. When NACK is received indicating poor conditions, the UE increases resolution to provide more accurate channel state information for improved scheduling decisions

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If sub-band CSI reports are transmitted frequently, then channel state information accuracy is improved, but uplink resource consumption increases

Engineering Contradiction:

Improvechannel state information accuracyVSAvoiduplink resource consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent implements periodic CSI reporting triggered by HARQ feedback events. Instead of continuous reporting, the UE reports CSI periodically when specific conditions are met (ACK or NACK reception), reducing overall uplink resource consumption while maintaining necessary channel state information accuracy

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent uses HARQ ACK/NACK feedback as a trigger mechanism for CSI reporting. The UE monitors downlink transmission outcomes and adjusts CSI reporting behavior based on this feedback, creating a closed-loop system where reporting frequency is determined by actual transmission needs and channel conditions

Inventive Principle:

Principle #23Feedback

3Quantity of substance

If reduced resolution CSI reports are transmitted, then uplink payload size is reduced, but channel state information accuracy deteriorates

Engineering Contradiction:

Improveuplink payload sizeVSAvoidchannel state information accuracy

Core Design Contradiction:

Quantity of substanceVSMeasurement precision

Solution Approach 1:

The patent dynamically switches between full resolution and reduced resolution reporting modes based on real-time transmission outcomes. The resolution is not fixed but adapts to current channel conditions, providing high accuracy when needed and saving resources when conditions are favorable

Inventive Principle:

Principle #15Dynamics

4Reliability

If CSI report resolution is adjusted based on ACK/NACK, then reliability of URLLC is improved, but system complexity increases

Engineering Contradiction:

Improvereliability of URLLCVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements a feedback-driven CSI reporting mechanism where the UE monitors HARQ ACK/NACK feedback and adjusts reporting behavior accordingly. This closed-loop approach improves reliability by adapting to actual transmission outcomes while keeping the decision logic relatively simple (ACK vs. NACK based determination)

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS11831375B2Sub-band channel state information reporting for ultra-reliable low latency communications

Publication Date: 2023.11.28 QUALCOMM INC

AI summary

Aspects relate to mechanisms for wireless communication devices to report sub-band (SB) channel state information (SB-CSI). A UE receives a physical downlink shared channel (PDSCH) transmission from a base station. The UE transmits either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission to the base station in response to a reception of the PDSCH transmission. The UE determines whether to transmit a sub-band (SB) channel state information (SB-CSI) report to the base station based on whether the ACK transmission is transmitted to the base station or whether the NACK transmission is transmitted to the base station.