Frequency Resource Allocation for CSI-RS in Wireless Systems

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Solution Overview

Problem

Current wireless communication systems, such as LTE Rel. 14 and NR, lack a determined frequency scheduling scheme for CSI-RS transmission, which affects efficient channel estimation and interference measurement.

Innovation Solution

The proposed solution involves allocating partial frequency resources to CSI-RS, CSI-Interference Measurement, and Zero Power CSI-RS, allowing for flexible and efficient resource allocation in wireless communication systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If beamforming is applied to CSI-RS to reduce overhead and increase coverage, then coverage and beamforming gain are improved, but frequency scheduling scheme becomes undetermined and resource allocation flexibility is reduced

Engineering Contradiction:
ImprovecoverageVSAvoidfrequency scheduling flexibility
Core Design Contradiction:
Volume of moving objectVSAdaptability or versatility

Solution Approach 1:

The system bandwidth is divided into multiple subbands, and CSI-RS resources are allocated to different subbands. This segmentation allows beamformed CSI-RS to be transmitted in specific frequency regions while maintaining scheduling flexibility for other bands, resolving the contradiction between coverage enhancement and frequency scheduling adaptability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces dynamic frequency scheduling for beamformed CSI-RS by allowing the network to flexibly configure and reconfigure frequency resources based on channel conditions and traffic requirements. This dynamic allocation maintains the beamforming coverage benefits while adapting to changing system demands.

Inventive Principle:
Principle #15Dynamics

2Measurement precision

If CSI-RS is transmitted in all resource blocks, then channel estimation accuracy is improved, but resource overhead increases

Engineering Contradiction:
Improvechannel estimation accuracyVSAvoidresource overhead
Core Design Contradiction:
Measurement precisionVSQuantity of substance

Solution Approach 1:

Instead of uniformly transmitting CSI-RS across all resource blocks, the patent applies local quality by transmitting beamformed CSI-RS in specific subbands where it provides the most benefit. This localized approach maintains channel estimation accuracy in critical frequency regions while reducing overall resource overhead.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The system transmits CSI-RS in a partial set of resource blocks (specific subbands) rather than all resource blocks. This partial action is sufficient to achieve effective channel estimation for the scheduled data transmissions while significantly reducing the overhead compared to full-bandwidth CSI-RS transmission.

Inventive Principle:
Principle #16Partial or excessive action

3Power

If frequency scheduling is not determined for CSI-RS, then beamforming gain is maintained, but resource allocation efficiency and system performance deteriorate

Engineering Contradiction:
Improvebeamforming gainVSAvoidresource allocation efficiency
Core Design Contradiction:
PowerVSProductivity

Solution Approach 1:

The patent creates a universal frequency scheduling framework that works with beamformed CSI-RS by defining flexible resource allocation mechanisms applicable to different scenarios. This multi-functional approach allows the system to maintain beamforming gains while achieving efficient resource allocation through unified scheduling principles.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP4030675B1Method of frequency resource allocation
Publication Date: 2025.05.21 NTT DOCOMO INC
  • EP4030675B1 patent drawingFigure 1
  • EP4030675B1 patent drawingFigure 2A~2B
  • EP4030675B1 patent drawingFigure 3A~3B

AI summary

A user equipment (UE) (10) comprising a receiving section (1031) configured to receive, by higher layer signaling, information indicating a resource including at least one of a reference signal resource for channel measurement and a resource for interference measurement; a control section (104) configured to perform, based on the information, at least one of channel measurement and interference measurement; and a transmitting section (1031) configured to transmit feedback information based on at least one of the channel measurement and the interference measurement, wherein the resource including at least one of the reference signal resource for the channel measurement and the resource for the interference measurement is allocated to one or more frequency resources within a carrier bandwidth part.