Optical Link Dynamic Range Determination in HFC Networks

Solution Overview

Problem

Detecting laser clipping in HFC networks is challenging due to the burstiness of signals, requiring labor-intensive and costly manual diagnostic processes involving multiple technicians and specialized equipment.

Innovation Solution

An automated method using a controller to instruct network elements to transmit signals at specific frequencies, allowing power monitoring to determine the dynamic range of optical links without requiring technicians to be present at remote locations, utilizing existing DOCSIS terminal devices and headend equipment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If manual diagnostic processes are used to detect laser clipping, then measurement precision can be achieved, but device complexity and loss of time increase significantly

Engineering Contradiction:

Improvelaser clipping detection accuracyVSAvoiddiagnostic time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The system performs preliminary characterization of the optical link by having network elements transmit test signals at different power levels before actual operation. The headend measures returned signals to determine the dynamic range and identify the laser clipping threshold in advance, so that when laser clipping occurs during normal operation, the pre-established model can quickly determine if the measured signal exceeds the characterized threshold, enabling rapid detection without manual intervention.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system enables automated self-diagnosis by having network elements transmit test signals and the headend automatically measure and analyze the returned signals. The controller compares measured signal characteristics against pre-characterized dynamic range parameters to automatically detect laser clipping conditions, eliminating the need for technicians to manually travel to remote locations with specialized equipment.

Inventive Principle:

Principle #25Self-service

2Measurement precision

If manual diagnostic processes are used to detect laser clipping, then measurement precision can be achieved, but device complexity increases due to requirement of specialized test equipment

Engineering Contradiction:

Improvelaser clipping detection accuracyVSAvoidtest equipment requirements

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The system makes existing network elements serve dual purposes: they function as both data transmission devices and as test signal transmitters for dynamic range characterization. The headend uses its existing receiver and controller to measure test signals and determine optical link parameters, eliminating the need for separate specialized test equipment such as vector signal analyzers and signal generators that would otherwise be required for manual diagnostics.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system enables automated self-diagnosis by having network elements transmit test signals and the headend automatically measure and analyze the returned signals. The controller compares measured signal characteristics against pre-characterized dynamic range parameters to automatically detect laser clipping conditions, eliminating the need for technicians to manually travel to remote locations with specialized equipment.

Inventive Principle:

Principle #25Self-service

3Device complexity

If existing network elements are used for dynamic range characterization, then device complexity is reduced, but measurement precision may be affected

Engineering Contradiction:

Improvetest equipment requirementsVSAvoiddynamic range measurement accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The system performs preliminary characterization of the optical link by having network elements transmit test signals at different power levels before actual operation. The headend measures returned signals to determine the dynamic range and identify the laser clipping threshold in advance, so that when laser clipping occurs during normal operation, the pre-established model can quickly determine if the measured signal exceeds the characterized threshold, enabling rapid detection without manual intervention.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS9088355B2Method and apparatus for determining the dynamic range of an optical link in an HFC network

Publication Date: 2015.07.21 ARRIS ENTERPRISES LLC

AI summary

The dynamic range of an optical link in a network is determined by simultaneously transmitting signals from two network elements at first and second frequencies, which create a combined signal at a third frequency. The transmission power levels of selected network elements is successively increased until the measured power from the third frequency no longer changes in a predictable manner, at which point the upper limit of the dynamic range of the optical link is determined.