Terminal DMRS Control with Separate FD-OCC Codes for UL and DL

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Solution Overview

Problem

Future radio communication systems face challenges in controlling uplink and downlink transmissions using demodulation reference signals (DMRS) ports, particularly when the number of ports is increased, leading to potential interference and reduced communication quality.

Innovation Solution

A terminal and base station are designed to support the application of different frequency domain orthogonal cover codes (FD-OCC) for downlink and uplink shared channels, enabling effective control of DMRS ports.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the number of DMRS ports is increased to support higher capacity and more layers, then the communication capacity and orthogonality are improved, but the control complexity of UL and DL transmissions increases and interference between different transmissions may occur

Engineering Contradiction:
Improvecommunication capacityVSAvoidcontrol complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent segments the DMRS port control into separate FD-OCC code assignments for downlink and uplink transmissions. By dividing the control space and using distinct FD-OCC codes for each direction, the system manages increased DMRS ports without creating interference between UL and DL transmissions, thus resolving the control complexity issue while maintaining high capacity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies different FD-OCC codes specifically for downlink and uplink DMRS ports, creating localized quality control for each transmission direction. This ensures that downlink and uplink transmissions are orthogonally separated in the frequency domain, preventing interference while allowing both to utilize the increased number of DMRS ports for high capacity communication

Inventive Principle:
Principle #3Local quality

2Productivity

If the number of DMRS ports is increased to support more layers and higher capacity, then the communication capacity is improved, but interference between UL and DL transmissions increases

Engineering Contradiction:
Improvecommunication capacityVSAvoidtransmission interference
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces FD-OCC codes as intermediary elements that mediate between downlink and uplink transmissions. These codes act as orthogonal separators that prevent interference between UL and DL DMRS ports while allowing both directions to operate simultaneously at high capacity. The FD-OCC codes serve as the intermediary structure that enables coexistence without mutual interference

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP4604471A1Terminal, wireless communication method, and base station
Publication Date: 2025.08.20 NTT DOCOMO INC
  • EP4604471A1 patent drawingFigure 1
  • EP4604471A1 patent drawingFigure 2
  • EP4604471A1 patent drawingFigure 3

AI summary

A terminal according to an aspect of the present disclosure includes a receiving section that receives downlink control information scheduling at least one of a downlink shared channel and an uplink shared channel each with a demodulation reference signal (DMRS) to which a length-4 frequency domain orthogonal cover code (FD-OCC) is applied, and a control section that controls reception of the downlink shared channel and transmission of the uplink shared channel, wherein application of different FD-OCC codes is supported for a DMRS for the downlink shared channel and a DMRS for the uplink shared channel.