Echo Cancellation for Timing-Varying HFC Channels
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Solution Overview
Problem
Hybrid Fiber-Coaxial (HFC) networks face challenges in echo cancellation due to timing varying channels, which cause adverse effects on echo cancellation performance, particularly in full duplex DOCSIS operations, leading to deteriorated signal quality and interference.
Innovation Solution
The implementation of a digital echo cancellation process that determines and updates echo cancellation coefficients to account for changing channel conditions, using a multi-branch receiver and echo cancellation training window to select the optimal coefficients for effective echo cancellation, even in the presence of rapid changes such as swinging cables or temperature fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional echo cancellation is used in HFC networks, then basic echo cancellation is provided, but timing varying channels cause deteriorated signal quality and interference
Solution Approach 1:
The patent implements dynamic echo cancellation coefficients that adapt to changing channel conditions. The system continuously updates coefficients based on real-time feedback signals and channel state, allowing the echo canceller to track and compensate for timing variations caused by swinging cables or temperature fluctuations, thereby maintaining reliable echo cancellation performance in dynamic HFC network environments
Solution Approach 2:
The patent employs a feedback mechanism where the echo canceller receives feedback signals from the network and uses these signals to update echo cancellation coefficients. This closed-loop feedback system enables the coefficients to be dynamically adjusted based on actual channel conditions, effectively counteracting interference from timing varying channels and improving overall echo cancellation reliability
2Reliability
If echo cancellation coefficients are dynamically updated to handle timing varying channels, then echo cancellation performance is maintained, but system complexity increases
Solution Approach 1:
The patent changes the parameters of echo cancellation coefficients dynamically based on channel conditions. By adjusting coefficient values in response to timing variations and using feedback signals to modify these parameters, the system maintains effective echo cancellation performance while managing the complexity through parameter adaptation rather than structural complexity
Data Source
AI summary
Echo cancellation to alleviate timing varying channels may be provided. First, a feedback signal corresponding to one of a plurality of downstream paths and a combination upstream signal comprising a combination of upstream signals from a plurality of upstream paths may be received. Next, a plurality of echo corrected signals may be created using the feedback signal, the combination upstream signal, and a plurality of echo cancelation coefficients that each respectively correspond to each one of the plurality of echo corrected signals and that are different from each other. Then a one of the plurality of echo cancelation coefficients that corresponds to a one of the plurality of echo corrected signals that provides a best echo cancelation performance as compared to other ones of the plurality of echo corrected signals may be selected to use.