CSI-RS Beam Selection from Uplink Pilots for High-Mobility NR

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Solution Overview

Problem

In the context of a Type II port selection codebook in a new radio (NR) system, terminals moving at medium to high speeds face challenges with increased uplink feedback overhead due to the need for shorter CSI feedback periods for accurate precoding, which is not effectively addressed by existing methods.

Innovation Solution

A method involving a network device receiving uplink pilot signals at multiple consecutive moments to estimate uplink channel information, determining a CSI-RS beam based on this information, and sending a beamformed CSI-RS to the terminal, allowing for reduced feedback overhead and shorter feedback periods by incorporating Doppler shift information.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the CSI feedback period is shortened to maintain accurate precoding for terminals moving at medium to high speeds, then the precision of channel state information is improved, but the uplink feedback overhead increases

Engineering Contradiction:

Improvechannel state information precisionVSAvoiduplink feedback overhead

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent extracts only the essential channel state information parameters needed for precoding (such as channel quality indicator and precoding matrix indicator) while discarding redundant feedback content. This selective extraction maintains precoding accuracy for moving terminals while significantly reducing the volume of uplink feedback data that needs to be transmitted.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The network device performs preliminary channel estimation and precoding calculation based on uplink channel measurements before the terminal needs to provide feedback. By pre-determining the precoding parameters using downlink-uplink channel reciprocity, the system reduces the amount of feedback the terminal must transmit, thereby lowering uplink overhead while maintaining accurate precoding for mobile scenarios.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If the CSI feedback period is shortened to track channel changes for high-speed terminals, then the reliability of communication is improved, but the uplink signaling overhead increases

Engineering Contradiction:

Improvecommunication reliabilityVSAvoiduplink signaling overhead

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The network device utilizes the uplink pilot signals transmitted by the terminal to perform self-service channel estimation and precoding calculation. By leveraging uplink channel measurements and channel reciprocity, the network device can autonomously determine downlink precoding parameters without requiring the terminal to measure and feedback detailed channel state information, thus maintaining communication reliability for high-speed terminals while minimizing uplink signaling overhead.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent implements a streamlined feedback mechanism where the terminal provides only essential CSI parameters (such as CQI and PMI) rather than complete channel matrices. The network device uses this reduced feedback combined with uplink channel measurements to maintain accurate precoding for high-speed terminals, achieving a balance between communication reliability and reduced uplink signaling overhead.

Inventive Principle:

Principle #23Feedback

3Quantity of substance

If the feedback period is extended to reduce uplink overhead, then the uplink feedback overhead is reduced, but the precision of precoding information deteriorates for moving terminals

Engineering Contradiction:

Improveuplink feedback overheadVSAvoidprecoding information precision

Core Design Contradiction:

Quantity of substanceVSMeasurement precision

Solution Approach 1:

The patent replaces the traditional terminal-based channel measurement and feedback mechanism with a network device-based uplink channel estimation approach. Instead of relying on terminal measurements and feedback, the network device performs channel estimation using uplink pilot signals and applies channel reciprocity to determine downlink precoding parameters. This substitution eliminates the need for frequent terminal feedback while maintaining precoding accuracy for moving terminals through extended feedback periods.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Quantity of substance

If the feedback period is extended to reduce signaling overhead, then the uplink resource consumption is reduced, but the adaptability to channel changes for high-speed terminals deteriorates

Engineering Contradiction:

Improveuplink resource consumptionVSAvoidchannel adaptability

Core Design Contradiction:

Quantity of substanceVSAdaptability or versatility

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS20250286589A1Method and device for determining channel state information (CSI)

Publication Date: 2025.09.11 BEIJING XIAOMI MOBILE SOFTWARE CO LTD

AI summary

A method and device for determining channel state information (CSI) are provided. The method includes: receiving uplink pilot signals sent by a terminal at T consecutive moments; performing uplink channel estimation on the uplink pilot signals to determine uplink channel information at each moment, wherein T is an integer greater than 1; determining a channel state information reference signal (CSI-RS) beam according to the uplink channel information; sending a beamformed CSI-RS to the terminal according to the CSI-RS beam; and receiving CSI reported by the terminal.