Cable Modem Channel Segmentation for Isolated Impairment Handling
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Solution Overview
Problem
Cable modem systems face disruptions due to high FEC issues and low SNR in a small subset of modems, affecting overall channel performance and throughput, as existing mechanisms often require channel-wide parameter changes in response, impacting optimally performing modems.
Innovation Solution
Implementing a mechanism to collect metrics on a per-cable-modem basis, identifying impaired modems and moving them to target channels with compatible modulation profiles, thereby preventing channel-wide parameter changes and maintaining maximum rates for other modems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If channel-wide parameter changes are implemented to address FEC issues and low SNR in impaired modems, then the reliability of impaired modems is improved, but the productivity of optimally performing modems deteriorates due to reduced data rates
Solution Approach 1:
The patent segments the upstream channel into multiple logical channels, allowing impaired modems to be moved to a dedicated logical channel with more robust parameters (lower data rate, higher error tolerance). This segmentation enables differentiated treatment: impaired modems receive reliability improvements on their assigned channel while optimally performing modems maintain high productivity on the original channel without being affected by parameter changes.
Solution Approach 2:
The patent applies local quality by assigning different parameter sets to different logical channels based on the specific needs of modems using them. The first logical channel is configured with parameters optimized for impaired modems (lower data rate, higher robustness), while the second logical channel maintains parameters optimized for high performance. This allows each group of modems to operate with locally optimized quality characteristics.
2Productivity
If per-channel configuration is used to optimize upstream parameters, then the productivity of individual channels is improved, but the adaptability to handle mixed performance levels of multiple modems deteriorates
Solution Approach 1:
The patent divides a single physical upstream channel into multiple logical channels, each with its own configuration parameters. This segmentation allows the system to maintain high productivity on each logical channel while simultaneously providing adaptability to accommodate modems with different performance levels by assigning them to appropriate logical channels based on their capabilities and channel conditions.
Solution Approach 2:
The patent introduces dynamic channel assignment where modems can be moved between logical channels based on changing conditions. The system can dynamically determine when to move a modem from the first logical channel to the second logical channel based on metrics such as error rates and signal quality, providing adaptability while maintaining optimal productivity configurations.
Data Source
AI summary
Disclosed are apparatus and methods for managing upstream channels on a per cable modem basis. In certain embodiments, one or more thresholds are defined for each of a plurality of upstream logical channels of a headend system for receiving data from a plurality of cable modems (or other types of access nodes). Each defined threshold corresponds to a measurable parameter of the corresponding upstream logical channel. One or more metrics are collected for each cable modem of each upstream logical channel. It is determined whether to downgrade a selected cable modem to a selected one of the logical channels that has a lower performance level than the selected cable modem's current logical channel. Such downgrade determination is based on whether the selected cable modem's collected one or more metrics have failed a condition of the one or more defined thresholds and whether a percentage of a total of the cable modems of such current logical channel that have failed a condition for the one or more defined thresholds is less than a predefined percentage level. The selected cable modem is then caused to move from the current logical channel to the selected logical channel when the percentage of the total cable modems that have failed is below a predefined level if such selected logical channel is available. Otherwise, the current logical channel's modulation profile may be altered when the percentage of the total cable modems that have failed is above (or equal to) the predefined level.