Upstream Signal Quality Monitoring via Packet MER Analysis
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Solution Overview
Problem
The upstream path monitoring in DOCSIS 3.0 protocols faces challenges due to increased bandwidth demand, making it difficult to detect noise and impairments in a crowded spectrum, leading to potential false prioritization of maintenance tasks and revenue impact.
Innovation Solution
A system that monitors upstream signals in a CATV bi-directional network using a demodulator to determine the Modulation Error Ratio (MER) for each packet, providing a graphical user interface to display MER as a function of packet number, allowing identification of network and individual cable modem issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If upstream bandwidth capacity is increased to meet growing data demands, then network throughput and service capability are improved, but the ability to detect noise and impairments deteriorates due to crowded spectrum
Solution Approach 1:
The patent introduces a test signal as an intermediary carrier wave that is modulated with known test data and injected into the upstream path. This test signal acts as a mediator that allows measurement of noise and impairments without being affected by the crowded spectrum carrying actual customer data. The test signal's known characteristics enable precise measurement of signal degradation despite the presence of multiple active data channels.
Solution Approach 2:
The patent creates a copy of the upstream transmission path by injecting a test signal that travels through the same physical medium (upstream channel) as the actual data traffic. This copied path allows independent measurement and monitoring of signal quality without interfering with or being obscured by the primary data transmission, enabling detection of impairments in the crowded spectrum environment.
2Device complexity
If conventional monitoring methods are used in crowded spectrum, then system simplicity is maintained, but measurement accuracy deteriorates leading to false prioritization of maintenance tasks
Solution Approach 1:
The patent extracts the measurement function from the crowded data spectrum by using a separate test signal with known characteristics. Instead of trying to measure quality in the mixed traffic spectrum, the test signal is extracted and monitored independently, allowing precise measurement of noise and impairments without the interference and complexity of analyzing multiple overlapping data channels.
Solution Approach 2:
The patent changes the measurement parameter from analyzing complex mixed traffic signals to measuring the known test signal parameters (such as carrier-to-noise ratio, modulation error ratio). By changing to these well-defined parameters with known expected values, the system achieves high measurement precision while maintaining relative simplicity in the monitoring approach.
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
This approach enables more accurate and actionable alarms, prioritizing maintenance based on real-time signal quality, reducing false positives, and identifying specific modem or network problems, thereby optimizing revenue impact and maintenance scheduling.
Implementation Method 1
a first demodulator for receiving and demodulating the packets in the upstream signal
Data Source
AI summary
The problem is that a measurement of the average signal quality (average modulation error ratio), does not identify poor quality signals that may be originating from an individual cable modem. The device of the present invention displays the modulation error ratio (MER) for each packet received. Since the media access control (MAC) address is associated with a packet received from an individual cable modem, a graph displaying the MER for each packet received is also displaying the MER for signals from the individual cable modems. Thus a technician viewing the display will be able to identify whether a low MER is a result of an impairment in the network or the from an individual cable modem.