DOCSIS Upstream Logical Channels for Cable Modem Throughput
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Solution Overview
Problem
Existing cable modem termination systems (CMTS) in DOCSIS systems are limited by the need to set upstream burst profiles to the lowest common denominator, resulting in lower average throughput due to the inadequacy of a small number of less capable cable modems, which penalizes all modems on the channel.
Innovation Solution
The system divides cable modems into logical groups based on their DOCSIS type and throughput ability, creating separate upstream logical channels with tailored burst profiles for each group, allowing high-throughput modems to operate with less robust but higher throughput profiles and lesser modems with more robust but lower throughput profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the upstream burst profile is set to the lowest common denominator to ensure all cable modems can comply, then reliability is improved for legacy modems, but productivity decreases for the entire channel
Solution Approach 1:
The patent segments the single upstream channel into multiple logical channels, each with its own burst profile optimized for specific modem types. DOCSIS 1.0 modems are assigned to one logical channel with robust error correction, while DOCSIS 2.0 modems are assigned to another logical channel with higher throughput settings, allowing each group to operate at its optimal performance level without being constrained by the lowest common denominator
Solution Approach 2:
The patent applies local quality by creating burst profiles with different characteristics for different logical channels. Each logical channel has locally optimized parameters (symbol rate, modulation scheme, forward error correction levels) tailored to the specific capabilities of the modems using that channel, rather than applying a uniform burst profile across all modems
2Reliability
If robust error correction protection is provided for the worst cable modem, then reliability is improved for that modem, but productivity is penalized for all modems on the upstream
Solution Approach 1:
The patent segments modems into logical groups based on their capabilities and assigns each group to a dedicated logical channel with appropriately tailored error correction levels. Legacy DOCSIS 1.0 modems receive robust error correction on their dedicated channel, while DOCSIS 2.0 modems use channels with less aggressive error correction, allowing high-throughput modems to operate at full speed without being dragged down by the error correction overhead required for legacy modems
3Device complexity
If a single upstream channel is used for all cable modems, then device complexity is reduced, but productivity decreases due to throughput penalties
Solution Approach 1:
The patent makes the upstream receiver multi-functional by enabling it to simultaneously process multiple logical channels, each optimized for different modem types. The single physical upstream channel is divided into multiple logical channels that can be independently configured and managed, allowing the system to serve both legacy and modern modems at their respective optimal throughput levels without requiring separate physical channels for each modem type
Data Source
AI summary
A process for grouping cable modems by type/modulation profile and/or throughput ability into different logical groups. Each logical group is commanded to transmit on an upstream which has a burst profile set to effectively use the throughput ability of the cable modem. Some species monitor initial ranging bursts and separate CMs with inadequate power onto a lower throughput upstream. Some species monitor post registration data transmissions for various factors and subdivide groups into subgroups of overperformers and underperformers.