Communication Channel Impairment Diagnosis Using CMTS Signal Tests
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Solution Overview
Problem
Current methods for diagnosing phase noise and distortion-based impairments in hybrid fiber coaxial (HFC) communication channels are manual, time-consuming, and expensive, requiring technicians to inject test signals at multiple locations within the HFC plant.
Innovation Solution
Automated processes, including total power loading, signal power reduction, noise power, and interleaver effectiveness tests, are used to remotely identify dominant impairments in communication channels by measuring parameters like MER, SNR, PER, and BER, distinguishing between noise and distortion-based impairments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual diagnostic methods with specialized equipment are used, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The system uses existing network elements (cable modems) to generate test signals and the CMTS receiver to measure impairments, eliminating the need for external specialized test equipment. The network infrastructure serves itself for diagnostic purposes by utilizing its own components for both signal generation and measurement.
Solution Approach 2:
The CMTS receiver performs multiple functions: it serves as both the communication receiver for normal operations and the measurement instrument for impairment diagnosis. The same receiver hardware that processes customer data signals is also used to measure MER, SNR, and other channel characteristics, eliminating the need for separate specialized test equipment.
2Measurement precision
If technicians are deployed to multiple locations simultaneously, then measurement precision is improved, but loss of time and productivity decrease
Solution Approach 1:
The distributed network elements (cable modems) autonomously generate test signals without requiring technician presence at each location. The system self-configures and self-measures impairments by having network elements transmit test signals and the CMTS automatically measure and report results, eliminating the need for simultaneous technician deployment.
Solution Approach 2:
The CMTS acts as an intermediary that collects measurement data from multiple distributed network elements and synthesizes the impairment diagnosis centrally. Instead of requiring technicians at multiple locations to simultaneously take measurements, the CMTS coordinates the test signal generation and measurement collection across the network, consolidating the diagnostic process at a single location.
3Productivity
If automated testing is implemented, then productivity is improved, but device complexity increases
Solution Approach 1:
The automation is achieved by having network elements and the CMTS perform diagnostic functions using existing capabilities. The cable modems autonomously transmit test signals when instructed, and the CMTS automatically measures impairments and generates diagnostic reports without requiring complex external testing equipment or manual intervention, achieving automation through the network's own components.
Data Source
AI summary
Methods are described for identifying a dominant impairment on a communication channel impaired by an interference issue. The methods include systematic examination of total power loading, systematic examination of signal power reduction, statistical examination of communication channel noise power, and systematic examination of interleaver effectiveness. Each relates to automatically diagnosing and characterizing distortion-based interference issues by monitoring the performance of a communication channel during a testing procedure. These methods enable a technician or engineer to remotely diagnose distortion-based interference issues relatively quickly without having to use external test equipment and without having to deploy technicians to various locations within the cable plant. A system by which these methods can be implemented is also disclosed.