Switched Filter Amp Circuit for Soft-Duplex Spectrum Sharing

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Solution Overview

Problem

Existing CATV systems bifurcate bandwidth into upstream and downstream transmissions, making it difficult to deliver multi-gigabit services and accommodate recent trends like DOCSIS 3.1 OFDM and distributed access architectures, as they lack a network architecture that allows spectrum sharing between upstream and downstream transmissions.

Innovation Solution

Implementing a Soft-FDX mode in cascaded Node+X architectures by using RF legs in FDD mode and dynamically or statically adjusting the upstream/downstream split using software, with amplifier circuits that include directional couplers, filters, and switches to manage spectrum allocation, allowing for flexible spectrum sharing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If spectrum is bifurcated into separate upstream and downstream transmissions, then interference between directions is minimized, but spectrum utilization efficiency deteriorates and multi-gigabit services cannot be delivered

Engineering Contradiction:

Improvetransmission reliabilityVSAvoidspectrum utilization efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent implements dynamic spectrum allocation where the upstream/downstream split point is not fixed but can be adjusted in real-time based on traffic demands. The system dynamically reconfigures which frequency channels are assigned to upstream versus downstream transmissions, allowing optimal spectrum utilization while preventing interference through coordinated switching at the HFC node and CMTS.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the frequency allocation parameters dynamically by adjusting the split frequency point between upstream and downstream bands. This allows the spectrum configuration to adapt to varying traffic conditions, enabling high-speed services while maintaining reliable separation of transmission directions through parameter reconfiguration.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If spectrum is shared between upstream and downstream transmissions, then spectrum utilization efficiency improves, but interference between directions increases

Engineering Contradiction:

Improvespectrum utilization efficiencyVSAvoidinterference

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an intermediary switching mechanism at the HFC node that acts as a mediator between upstream and downstream transmissions. The switch dynamically routes frequency channels, ensuring that when a channel is used for downstream transmission, it is blocked from upstream use, and vice versa. This intermediary switching function enables spectrum sharing while preventing interference through coordinated channel assignment.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system employs feedback mechanisms where the CMTS and HFC node continuously monitor spectrum usage and traffic conditions, then adjust the upstream/downstream split configuration accordingly. This feedback-driven dynamic reconfiguration allows the system to optimize spectrum utilization while maintaining interference-free operations by responding to real-time network conditions.

Inventive Principle:

Principle #23Feedback

3Device complexity

If fixed upstream/downstream split is used, then system complexity is reduced, but adaptability to different service requirements deteriorates

Engineering Contradiction:

Improvesystem complexityVSAvoidservice adaptability

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent transforms the static upstream/downstream split configuration into a dynamic system that can adapt to different service requirements. The HFC node and CMTS can reconfigure the frequency allocation based on whether the network needs to optimize for downstream video delivery, upstream data transmissions, or balanced bidirectional communication, providing service-specific adaptability without requiring fundamentally different system architectures.

Inventive Principle:

Principle #15Dynamics

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables high upstream speeds and efficient use of downstream spectrum, supporting FDX operation while minimizing interference and maintaining high throughput without disrupting legacy services.

Implementation Method 1

a first directional coupler having a first input port, a first output port, a second output port, and a first coupled port

Methodology Applied

Scientific EffectDirectional coupling:

Implementation Method 2

a first bandpass filter connected to the first switch, the first bandpass filter having a first passband

Methodology Applied

Scientific EffectFrequency filtering: Filter (electronic)

Implementation Method 3

a second bandpass filter connected to the second switch, the second bandpass filter having a second passband

Methodology Applied

Scientific EffectFrequency filtering: Filter (electronic)

Implementation Method 4

an amplifier connected to the second directional coupler

Methodology Applied

Scientific EffectSignal amplification: Magnetic Amplifier

Data Source

PatentEP4062633B1Switched filter amp circuit for soft duplex CATV architectures

Publication Date: 2026.02.11 ARRIS ENTERPRISES LLC

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Figure 2A~2B
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AI summary

Systems and methods for implementing Soft-duplex functionality in an amplifier in a HFC network.