Full Duplex DOCSIS Echo Cancellation Training
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Solution Overview
Problem
Conventional approaches for echo cancellation in cable networks are costly, cumbersome, and inefficient, particularly in full duplex DOCSIS cable modem systems where upstream transmissions introduce significant interference into downstream signals, degrading signal quality.
Innovation Solution
The implementation of full duplex DOCSIS cable modem echo cancellation training using live signals and circuitry that includes digital signal processors, analog-to-digital and digital-to-analog converters, and interference cancellers to dynamically estimate and correct echo, allowing for efficient cancellation of adjacent channel and leakage interference without disrupting existing systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional echo cancellation approaches are used in full duplex DOCSIS cable modem systems, then system compatibility is maintained, but echo interference severely degrades downstream signal quality
Solution Approach 1:
The system performs preliminary echo cancellation training during upstream transmission phases before downstream reception begins. The cable modem termination system (CMTS) sends training sequences during upstream slots, allowing the cable modem to pre-calibrate echo cancellation coefficients. This preliminary action ensures that when downstream signals arrive, the echo from upstream transmissions is already cancelled, preventing signal quality degradation rather than correcting it afterward.
Solution Approach 2:
The system implements a feedback mechanism where the cable modem monitors downstream signal quality and adjusts echo cancellation parameters accordingly. The CMTS receives feedback about signal conditions and dynamically adjusts the upstream transmission power and training sequence characteristics. This closed-loop feedback ensures continuous optimization of echo cancellation performance, maintaining reliable downstream reception even as network conditions change.
2Object-affected harmful factors
If specialized training sequences are implemented for echo cancellation training, then echo cancellation performance is improved, but system complexity and cost increase
Solution Approach 1:
The system uses universal upstream data transmission sequences that serve dual purposes: carrying actual upstream data and providing training signals for echo cancellation. Instead of requiring separate specialized training sequences, the existing upstream transmission structures are leveraged for both data communication and echo calibration. This multi-functionality approach achieves effective echo cancellation without adding dedicated training overhead or increasing system complexity.
Solution Approach 2:
The cable modem performs self-calibration of echo cancellation parameters using its own upstream transmissions. The system extracts echo paths by correlating transmitted upstream signals with received downstream signals, allowing the modem to automatically determine and adjust cancellation coefficients without external assistance. This self-service capability eliminates the need for complex external training equipment or specialized training protocols, reducing overall system complexity while maintaining effective echo cancellation.
Data Source
AI summary
Systems and methods are provided for full duplex DOCSIS cable modem echo cancellation with training. During reception of downstream signals, echo effects on downstream signals may be determined, with at least some of the echo effects corresponding to concurrently transmitted upstream signals. Echo cancellation corrections may be determined based on the determined echo effects, and the echo cancellation corrections may be applied during processing of the downstream signals. The echo cancellation corrections may include one or both of ACI (adjacent channel interference) cancellation corrections and ALI (adjacent leakage interference) cancellation correction. The echo cancellation may include or be based on preforming echo cancellation training, during active communication and based on one or both of the downstream signals and the upstream signals.