Proactive Echo Cancellation Training in HFC Networks
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Solution Overview
Problem
In Hybrid Fiber-Coaxial (HFC) networks, existing echo cancellation techniques face challenges with frequent and always-on Echo Cancellation Training (ECT) opportunities due to rapid channel changes, leading to echo cancellation divergence and high bandwidth costs, especially in full duplex DOCSIS operations.
Innovation Solution
The implementation of proactive Echo Cancellation Training (ECT) through the proactive scheduling of Echo Cancellation Training Opportunities (ECTOs) by the Cable Modem Termination System (CMTS), which allocates mini-slots for explicit and implicit ECTOs, allowing for constant EC training at a low bandwidth cost, using both explicit mini-slot allocation and power detection to identify silent windows for training.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frequent and always-on Echo Cancellation Training (ECT) opportunities are provided to handle rapid channel changes, then echo cancellation performance is improved, but bandwidth consumption increases
Solution Approach 1:
The patent implements periodic Echo Cancellation Training Opportunities (ECTOs) at predefined time intervals rather than continuous training. The CMTS schedules ECTOs periodically in upstream bandwidth allocation, allowing the echo canceller to update coefficients at regular intervals. This periodic approach maintains adequate echo cancellation performance while significantly reducing bandwidth consumption compared to always-on training.
Solution Approach 2:
The patent performs echo cancellation training in advance during scheduled ECTO periods before actual upstream data transmissions occur. The CMTS proactively allocates ECTO mini-slots in the upstream bandwidth map, allowing the echo canceller to pre-update its coefficients. This preliminary action ensures the echo canceller is ready for rapid channel changes without requiring continuous training during data transmissions.
2Stability of the object's composition
If continuous Echo Cancellation Training is performed to maintain effective echo cancellation under fast interference conditions, then echo cancellation stability is improved, but available bandwidth for data transmission decreases
Solution Approach 1:
The patent segments the upstream bandwidth into distinct mini-slots, dedicating specific mini-slots for Echo Cancellation Training Opportunities (ECTOs) and other mini-slots for data transmission. The TFCP scheduler allocates ECTO mini-slots periodically rather than continuously, creating separate time segments for training and data. This segmentation allows the system to maintain echo cancellation stability during designated training periods while maximizing data transmission capacity during remaining periods.
3Loss of substance
If proactive scheduling of Echo Cancellation Training Opportunities is implemented, then bandwidth overhead is reduced, but complexity of training scheduling increases
Solution Approach 1:
The patent implements self-service mechanisms where the CMTS autonomously schedules ECTO mini-slots based on predefined parameters and algorithms. The TFCP scheduler automatically identifies suitable upstream mini-slots for ECTOs, manages the scheduling without manual intervention, and dynamically adjusts ECTO allocations based on channel conditions and traffic patterns. This automation reduces the operational complexity of managing proactive ECT scheduling while minimizing bandwidth overhead.
Data Source
AI summary
Proactive Echo Cancellation (EC) training may be provided. First, a plurality of Echo Cancellation Training Opportunities (ECTOs) may be identified in an upstream bandwidth allocation. Identifying the ECTOs may comprise identifying a corresponding plurality of mini-slots in a two dimensional time frequency space designated as not to be used for Upstream (US) traffic. Then Echo Cancellation Training (ECT) may be conducted for each of the plurality of ECTOs.