IAB Relay Power Control for MT-DU Signal Separation

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Solution Overview

Problem

In 3GPP Release 17, IAB nodes face challenges in maintaining communication quality due to large power differences between MT and DU signals, leading to signal separation issues in multiplexing environments, especially when antennas and RF circuits are shared or closely spaced, resulting in deteriorated reception performance.

Innovation Solution

The IAB node implements transmission power control by adjusting the power difference between uplink and downlink signals to within a predetermined value through commands to upstream and downstream devices, using power measurement units and control units to manage signal power levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the IAB node receives signals simultaneously with both MT and DU functions, then communication efficiency is improved, but signal separation becomes difficult and communication quality deteriorates due to large power differences between MT-addressed and DU-addressed signals

Engineering Contradiction:
Improvecommunication efficiencyVSAvoidcommunication quality
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent changes the power parameter of received signals by performing power control on the DU-addressed signal. Specifically, when the power difference between MT-addressed and DU-addressed signals exceeds a threshold, the patent adjusts (reduces) the power of the DU-addressed signal to fall within a predetermined range, thereby resolving the signal separation issue while maintaining simultaneous reception capability

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent implements a feedback mechanism where the IAB node measures the power difference between MT-addressed and DU-addressed signals, compares it with a threshold value, and adjusts the power of DU-addressed signals accordingly. This closed-loop control ensures that power differences remain within acceptable ranges, maintaining both communication efficiency and quality

Inventive Principle:
Principle #23Feedback

2Device complexity

If the MT antenna and DU antenna are closely spaced or share an antenna, then device complexity is reduced, but signal separation becomes difficult and reception performance deteriorates

Engineering Contradiction:
Improveantenna configuration complexityVSAvoidreception performance
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent compensates for the physical proximity of antennas by changing the power parameter of signals through control. When MT and DU antennas are closely spaced or shared, the patent measures the power difference between addressed signals and adjusts the DU-addressed signal power to maintain separation effectiveness despite the reduced physical distance between antennas

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP4132056B1Communication device, control method, and program for executing transmission power control in relay transmission
Publication Date: 2025.12.24 KDDI CORP
  • EP4132056B1 patent drawingFigure 1~2
  • EP4132056B1 patent drawingFigure 3
  • EP4132056B1 patent drawingFigure 4

AI summary

A communication device capable of connecting to and communicating with another device using a first function operating as a terminal device and a second function operating as a base station device, the communication device acquires a first reception power density of a signal of a downlink received from an upstream device connected by the first function, acquires a second reception power density of a signal of an uplink received from a downstream device connected by the second function, and transmits a transmission power control command for controlling transmission power of the signal of the downlink to the upstream device, based on the first reception power density and the second reception power density.