Single Feedback Path Digital Echo Cancellation
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Solution Overview
Problem
In Hybrid Fiber-Coaxial (HFC) networks, existing echo cancellation methods require multiple feedback paths to manage echoes and noise across multiple ports, leading to increased costs and complexity, especially for full duplex DOCSIS operations.
Innovation Solution
A digital echo cancellation process that utilizes a single feedback path to sample noise from all ports, leveraging non-linear correlation among downstream amplifiers and the upstream silence period to create an echo correcting signal, effectively canceling downstream echoes from the combination upstream signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple feedback paths are used to manage echoes and noise across multiple ports, then echo cancellation performance is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges multiple feedback paths into a single feedback path that samples noise from all ports simultaneously. This is achieved by combining the noise signals from multiple downstream amplifiers before feeding them to a single analog-to-digital converter, thereby reducing the number of feedback paths while maintaining echo cancellation performance through the non-linear correlation among amplifiers.
Solution Approach 2:
The single feedback path is designed to serve multiple functions by sampling noise from all ports simultaneously. The feedback signal contains noise information from multiple downstream amplifiers, allowing the system to manage echoes across multiple ports using one unified feedback mechanism rather than separate feedback paths for each port.
2Reliability
If multiple feedback paths are implemented for full duplex DOCSIS operations, then echo management is improved, but cost increases
Solution Approach 1:
The patent reduces system cost by merging multiple feedback paths into a single feedback path. This is achieved by combining noise signals from multiple ports before the analog-to-digital conversion stage, thereby reducing the number of required feedback components and lowering overall system cost while maintaining full duplex DOCSIS echo management capability.
3Device complexity
If a single feedback path is used to sample noise from all ports, then device complexity and cost are reduced, but measurement precision of individual port noise may deteriorate
Solution Approach 1:
The patent employs feedback mechanisms to maintain measurement precision despite using a single feedback path. The system uses the non-linear correlation among downstream amplifiers to reconstruct noise characteristics, and incorporates feedback loops that continuously adjust the echo correcting signal to compensate for the combined nature of the feedback signal, thereby preserving noise sampling accuracy.
Solution Approach 2:
The patent changes the parameter approach by transforming individual port noise measurements into a combined noise signal that leverages non-linear correlation properties. By changing from direct individual measurements to correlated combined measurements, the system maintains precision through the mathematical relationships between noise signals from different ports.
Data Source
AI summary
Echo cancellation may be provided. First, a feedback signal corresponding to a plurality of downstream paths may be received. Next, during an upstream silence period, a sample of a combination upstream signal may be received comprising a combination of upstream signals from a plurality of upstream paths. An echo correcting signal may then be created using the received feedback signal and the received sample of the combination upstream signal. Downstream echoes may be cancel from the combination upstream signal based on the created echo correcting signal.