SRS Precoder Determination via CSI-RS Timing Offset

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Solution Overview

Problem

In future radio communication systems, determining the appropriate SRS precoder for PUSCH transmission is challenging, leading to potential system throughput reductions due to unclear UE operations related to CSI-RS usage.

Innovation Solution

A user terminal identifies a reference resource for determining the SRS precoder, using the latest transmitted CSI-RS resource based on a defined timing offset, to accurately determine the SRS precoder for PUSCH transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the UE determines the SRS precoder based on CSI-RS without clear operation specifications, then the system flexibility is maintained, but the system throughput decreases due to ambiguous UE operations

Engineering Contradiction:
Improvesystem throughputVSAvoidUE operation clarity
Core Design Contradiction:
ProductivityVSEase of operation

Solution Approach 1:

The patent changes the parameter of CSI-RS resource identification from ambiguous to specific by introducing explicit timing relationship parameters (k0, k2) that define the exact offset between triggering DCI and CSI-RS transmission. This parameter specification resolves the operational ambiguity while maintaining system flexibility, directly improving throughput by ensuring correct precoder determination.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies preliminary action by pre-defining the timing relationship between DCI triggering and CSI-RS transmission through higher-layer parameters. This preliminary configuration ensures that the UE can correctly identify the reference CSI-RS resource before actual transmission occurs, eliminating operational ambiguity and enabling accurate SRS precoder determination.

Inventive Principle:
Principle #10Preliminary action

2Adaptability or versatility

If two DCIs are used to separately trigger CSI-RS and SRS, then the control flexibility is improved, but the signaling overhead increases and association ambiguity occurs

Engineering Contradiction:
Improvecontrol flexibilityVSAvoidsignaling overhead
Core Design Contradiction:
Adaptability or versatilityVSLoss of information

Solution Approach 1:

The patent merges the triggering function into a single DCI that simultaneously triggers both SRS and the associated CSI-RS using a unified SRS request field. This consolidation reduces signaling overhead by eliminating redundant triggering messages while maintaining control flexibility through the configurable timing parameters within the same DCI structure.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent enhances the universality of the DCI format by making the SRS request field serve multiple functions: it can trigger SRS transmission, trigger associated CSI-RS transmission, and encode timing relationship information. This multi-functionality reduces the need for separate DCIs while preserving control flexibility through configurable parameters.

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

Data Source

PatentEP3761695B1User terminal and wireless communication method
Publication Date: 2023.09.20 NTT DOCOMO INC
  • EP3761695B1 patent drawingFigure 1
  • EP3761695B1 patent drawingFigure 2
  • EP3761695B1 patent drawingFigure 3

AI summary

An SRS precoder is appropriately determined. A user terminal according to one aspect of the present disclosure includes: a control section that identifies a resource for a Channel State Information-Reference Signal (CSI-RS); and a transmitting section that transmits a Sounding Reference Signal (SRS) by using a precoder based on the latest transmitted resource.