RF Repeater Feedback Oscillation Suppression via Digital Extraction

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Solution Overview

Problem

Existing radio frequency repeaters face performance degradation due to feedback oscillations, requiring increased installation costs and reduced amplification gain to mitigate feedback signals, while existing solutions struggle to adapt to varying environmental conditions and ensure stable service quality.

Innovation Solution

A radio frequency repeater apparatus and method that combines analog and digital signal processing units to simultaneously analyze channel characteristics, update phase and amplitude of feedback signals, and control gain to eliminate feedback signals, ensuring adaptive operation and stability in diverse propagation environments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If transmitting and receiving antennas are placed far apart to increase isolation, then feedback oscillation is reduced, but installation cost increases

Engineering Contradiction:
Improvefeedback oscillation suppressionVSAvoidinstallation cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent extracts and eliminates the harmful feedback signal component from the received signal through digital signal processing. By separating the desired forward link signal from the harmful feedback oscillation component and removing the feedback component, the system achieves oscillation suppression without requiring increased antenna separation distance, thus avoiding higher installation costs.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces a digital signal processing unit as an intermediary between the receiving antenna and the signal output. This intermediary processes the received signal to remove feedback oscillation components, acting as a mediator that eliminates harmful effects without requiring physical changes to antenna positioning or system architecture.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If amplification gain is decreased to minimize feedback effects, then feedback oscillation is reduced, but signal amplification capability deteriorates

Engineering Contradiction:
Improvefeedback oscillation suppressionVSAvoidamplification gain
Core Design Contradiction:
ReliabilityVSPower

Solution Approach 1:

The patent extracts and removes the feedback oscillation component from the amplified signal through digital signal processing. By separating and eliminating the harmful feedback component after amplification, the system maintains high amplification gain capability while suppressing oscillation, avoiding the need to reduce the amplification gain setting.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The digital signal processing unit serves as an intermediary that processes the amplified signal to remove feedback oscillation components. This allows the amplification stage to operate at high gain without causing oscillation, as the feedback removal function compensates for the potential oscillatory effects.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Device complexity

If analog processing is used to eliminate feedback signals, then circuit construction is simple, but flexibility and accuracy are reduced

Engineering Contradiction:
Improvecircuit constructionVSAvoidprocessing flexibility
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent replaces the mechanical/analog signal processing approach with a digital signal processing approach. Instead of using analog circuits to adjust signal characteristics, the system uses digital algorithms to estimate and eliminate feedback components, achieving both simplicity in implementation and high flexibility in processing through software-based solutions.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP1839400B1Radio repeater for mobile communication system and repeating method using the same
Publication Date: 2013.02.27 SK TELECOM CO LTD
  • EP1839400B1 patent drawingFigure 1~2
  • EP1839400B1 patent drawingFigure 3~4
  • EP1839400B1 patent drawingFigure 5

AI summary

Disclosed herein is a radio frequency(RF) repeater comprising an analog signal processing unit and a digital signal processing unit, wherein the analog signal processing unit includes a filtering unit; an amplification unit on receiving side; a frequency conversion unit on receiving side; a frequency conversion unit on transmitting side; and an amplification unit on transmitting side, and the digital signal processing unit includes a receiving signal detection unit; the automatic gain control unit; a feedback signal detection unit; a feedback signal combining unit; a feedback signal elimination unit; an automatic delay control unit; and the control unit. According to the RF repeater and repeating method, installation cost is reduced, limitations in output magnitude and installation are overcome, and ensuring high output power characteristics.