Single-Symbol DMRS Port Configuration for Multi-Layer Uplink

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Solution Overview

Problem

Future radio communication systems face challenges in efficiently supporting more than 4 layers with single-symbol DMRS due to increased communication overhead from double-symbol DMRS, which suppresses data transmission capacity.

Innovation Solution

A terminal and base station that determine a combination of five or more DMRS ports based on an antenna port field in downlink control information for uplink and downlink shared channels, utilizing a single-symbol DMRS to support more than 4 layers, reducing communication overhead.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If double-symbol DMRS is used to support more than 4 layers, then the number of supported layers is improved, but communication overhead increases and data transmission capacity decreases

Engineering Contradiction:
Improvenumber of supported layersVSAvoidcommunication overhead
Core Design Contradiction:
Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The patent changes the parameter of DMRS configuration by introducing a new field in DCI that indicates whether to use single-symbol or double-symbol DMRS. This allows the system to adapt the DMRS configuration based on the number of layers being transmitted, using single-symbol DMRS for 5-8 layers when possible to reduce overhead, and reserving double-symbol DMRS for specific cases where additional layers are needed.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If double-symbol DMRS is used to support more than 4 layers, then the number of supported layers is improved, but communication throughput decreases

Engineering Contradiction:
Improvenumber of supported layersVSAvoidcommunication throughput
Core Design Contradiction:
Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent implements dynamic selection between single-symbol and double-symbol DMRS based on the transmission requirements. The base station determines the appropriate DMRS configuration dynamically based on the number of layers and communicates this selection through the new field in DCI, allowing the system to optimize throughput by using the more efficient single-symbol DMRS when sufficient layers are supported.

Inventive Principle:
Principle #15Dynamics

3Quantity of substance

If single-symbol DMRS is used to reduce overhead, then communication overhead is reduced, but the ability to support more than 4 layers is limited

Engineering Contradiction:
Improvecommunication overheadVSAvoidnumber of supported layers
Core Design Contradiction:
Quantity of substanceVSAdaptability or versatility

Solution Approach 1:

The patent segments the DMRS port configuration into two parts: existing DMRS ports for up to 4 layers and new additional DMRS ports for beyond 4 layers. This segmentation allows the system to use single-symbol DMRS with existing ports for basic operations while introducing new ports through a new DCI field when additional layers are required, thus reducing overhead while maintaining extendability.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP4576693A1Terminal, wireless communication method, and base station
Publication Date: 2025.06.25 NTT DOCOMO INC
  • EP4576693A1 patent drawingFigure 1
  • EP4576693A1 patent drawingFigure 2
  • EP4576693A1 patent drawingFigure 3A~3D

AI summary

A terminal according to an aspect of the present disclosure includes a receiving section that receives downlink control information (DCI) for scheduling an uplink shared channel, and a control section that, when a maximum length of a demodulation reference signal (DMRS) for the uplink shared channel is 1, determines a combination of five or more ports for the DMRS, based on an antenna port field of the DCI. According to an aspect of the present disclosure, it is possible to appropriately perform communication with more than 4 layers, based on a single-symbol DMRS.