TaFD Scheduler for DOCSIS 3.1 Spectrum Coordination
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Solution Overview
Problem
Existing DOCSIS networks face challenges in upstream resource allocation and scheduling due to noise funneling, distortion, burst transmission, and spectral overlap between different channel technologies, particularly when migrating from DOCSIS 3.0 to DOCSIS 3.1, where overlapping channels lack coordinated transmission scheduling.
Innovation Solution
A Time and Frequency Division (TaFD) scheduler is introduced, utilizing a TaFD allocation unit (TAU) based credit allocation system that dynamically adjusts credits based on channel utilization and demand, allowing for independent hierarchy priority queuing and communication between schedulers to prevent collisions and optimize spectrum use across overlapping channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If DOCSIS 3.1 OFDMA channels overlap with DOCSIS 3.0 SC-QAM channels to extend spectrum usage, then network capacity and peak rates are improved, but transmission collisions and interference occur due to lack of coordination between independent schedulers
Solution Approach 1:
The patent introduces a coordination mechanism that acts as an intermediary between the DOCSIS 3.0 SC-QAM scheduler and DOCSIS 3.1 OFDMA scheduler. This mediator enables the schedulers to exchange scheduling information and coordinate their transmissions, preventing collisions while allowing both channel types to operate simultaneously on overlapping frequencies, thus resolving the reliability issue without sacrificing network capacity
Solution Approach 2:
The patent merges the previously independent scheduling functions of SC-QAM and OFDMA channels into a unified coordinated scheduling system. By combining the scheduling decisions of both channel types under a single coordination framework, the system allows spectrum overlap to be exploited for increased capacity while maintaining transmission reliability through joint optimization
2Ease of operation
If independent schedulers are used for SC-QAM and OFDMA channels, then device complexity is reduced and ease of operation is improved, but spectrum utilization efficiency deteriorates due to inability to coordinate overlapping channel transmissions
Solution Approach 1:
The patent segments the scheduling function into two layers: independent scheduler modules that maintain their operational simplicity and a coordination layer that optimizes spectrum utilization. Each scheduler remains independently operable for its respective channel type, preserving ease of operation, while the coordination mechanism ensures efficient spectrum usage by preventing collisions and optimizing resource allocation across overlapping channels
3Productivity
If DOCSIS networks migrate to DOCSIS 3.1 OFDMA technology, then peak rates and service capacity are improved, but migration challenges increase due to spectral overlap and lack of coordination mechanisms between legacy and modern channels
Solution Approach 1:
The patent implements a dynamic coordination mechanism that adapts to the mixed DOCSIS 3.0 and 3.1 environment during migration. The coordination system dynamically adjusts scheduling decisions based on real-time channel conditions, traffic demands, and the presence of both legacy SC-QAM and modern OFDMA channels, enabling smooth migration while maintaining high peak rates without requiring complete system redesign
Data Source
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AI summary
A Time and Frequency Division (TaFD) scheduler based on a TaFD allocation unit based credit allocation may schedule both time and frequency division for both legacy Data Over Cable Service Interface Specification (DOCSIS) channels and DOCSIS orthogonal frequency division multiple access (OFDMA) channels. In embodiments, scheduling by the TaFD schedules both single carrier quadrature amplitude modulation (SC-QAM) transmissions and OFDMA upstream transmissions. In embodiments, the scheduler schedules based on TaFD allocation unit based credit allocations, where TaFD allocation unit based credits may be allocated for OFDMA overlapped regions. The credits may be dynamically adjusted based on channel utilization and an outstanding bandwidth demand or a prioritized pending bandwidth demand. The TaFD scheduler may use independent hierarchy priority queuing schemes.