CSI-RS Frequency Domain Density Reduction

Solution Overview

Problem

The transmission of reference signals in communications systems consumes valuable network resources, leading to increased communications overhead, necessitating a reduction in network resource usage.

Innovation Solution

Implementing frequency domain density reduction techniques for channel state information reference signals (CSI-RS) by transmitting them every L physical resource blocks (PRBs) and signaling the frequency domain density reduction rate and shift index to enable efficient detection, allowing for flexible scheduling and reduced overhead.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If reference signals are transmitted with high density in frequency domain, then measurement accuracy and synchronization are improved, but network resource consumption and communications overhead increase

Engineering Contradiction:

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

The frequency domain is segmented into multiple subbands, and reference signals are transmitted selectively in different subbands based on channel conditions and requirements. This allows dense reference signal transmission in subbands requiring accurate measurement while using sparse transmission in other subbands, thereby resolving the contradiction between measurement precision and network resource consumption

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different reference signal densities are applied to different frequency subbands based on local channel characteristics and measurement requirements. Subbands with poor channel conditions or high measurement requirements receive denser reference signals, while subbands with good conditions receive sparser signals, optimizing the balance between measurement accuracy and resource usage

Inventive Principle:

Principle #3Local quality

2Reliability

If reference signals are transmitted frequently, then channel state information accuracy is improved, but communications overhead increases

Engineering Contradiction:

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

Reference signals are transmitted periodically with configurable periods in different subbands. The transmission period can be adjusted based on channel variability and measurement requirements, allowing accurate channel state information to be obtained when needed while reducing overhead during stable channel conditions

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The reference signal transmission density and period are made dynamic and configurable based on channel conditions, measurement requirements, and system load. This allows the system to adaptively adjust the balance between channel state information accuracy and communications overhead rather than using fixed transmission patterns

Inventive Principle:

Principle #15Dynamics

Data Source

PatentEP3513536B1System and method for signal density reduction in frequency domain

Publication Date: 2020.07.29

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AI summary

A method for operating an access node includes sending, to a user equipment (UE), a frequency domain density reduction rate indicator and a frequency shift index indicator for one or more channel state indicator reference signal (CSI-RS) resources, wherein the frequency domain density reduction rate indicator indicates a number of physical resource blocks (PRBs) skipped between successive CSI-RS transmissions and the frequency shift index indicator indicates an offset of a CSI-RS starting PRB.