CMTS RF Bandwidth Allocation Fairness
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Solution Overview
Problem
The existing DOCSIS 3.0 wideband transmission scheme with existing arbitration methods leads to arbitrary allocation of RF channel bandwidth among service flows, failing to ensure bandwidth allocation is proportional to DOCSIS priority values or QoS metrics, especially when mixing narrowband and wideband transmissions on the same RF channel.
Innovation Solution
A Cable Modem Termination System (CMTS) dynamically reallocates RF channel bandwidth among DOCSIS bonding groups based on their DOCSIS priority, using a fairness scheme that balances active service flow activity with priority, recalculating target bandwidth amounts and adjusting allocations periodically to maintain proportionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wideband transmission scheme is used with existing arbitration schemes, then transmission capacity is improved, but bandwidth allocation fairness deteriorates
Solution Approach 1:
The patent implements dynamic bandwidth allocation by continuously monitoring service flow activity and adjusting RF channel bandwidth allocation in real-time. The CMTS recalculates target bandwidth amounts based on current flow activity and DOCSIS priority values, and retunes allocation periodically to maintain fairness despite changing network conditions. This dynamic approach resolves the contradiction by adapting the allocation scheme to actual usage patterns rather than using static arbitration.
Solution Approach 2:
The patent changes the allocation parameters from simple arbitration based on fixed rules to a sophisticated scheme that incorporates multiple parameters including DOCSIS priority values, service flow activity status, and target bandwidth amounts. By using these multiple parameters to guide allocation decisions, the system achieves both high transmission capacity utilization and fair bandwidth distribution among competing service flows.
2Productivity
If narrowband and wideband transmissions are mixed on the same RF channel, then spectral efficiency is improved, but allocation arbitrariness increases
Solution Approach 1:
The patent implements a feedback mechanism where the CMTS continuously monitors the activity status of service flows and the actual bandwidth allocation results. Based on this feedback, the system recalculates target bandwidth amounts and adjusts RF channel allocation to maintain fairness. This feedback loop ensures that mixing narrowband and wideband transmissions does not lead to arbitrary allocation, as the system continuously corrects imbalances based on actual usage and priority requirements.
Solution Approach 2:
The patent performs preliminary calculation of target bandwidth amounts before actual bandwidth allocation. By pre-determining the fair share of bandwidth each bonding group should receive based on DOCSIS priority and flow activity, the system guides subsequent allocation decisions. This preliminary action ensures that even when mixing narrowband and wideband transmissions, the allocation follows a deterministic fair sharing principle rather than being arbitrary.
Data Source
AI summary
In one example, a Cable Modem Termination System (CMTS) determines target Radio Frequency (RF) bandwidth amounts for Data Over Cable System Interface Specification (DOCSIS) bonding groups according to the DOCSIS priority of active flows within the bonding groups. The CMTS then tunes bandwidth allocation amongst the DOCSIS bonding groups according to the target bandwidth amounts. The target bandwidth amounts can be recalculated at intervals, and the bandwidth allocation re-tuned at the intervals, to account for changes in flow activity or DOCSIS priority assignment.