Echo Cancellation Using Dynamic Step-Size Control
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Solution Overview
Problem
Existing echo signal cancellation techniques in teleconferencing applications face high computational complexity and large delays in frequency domain methods, while time domain techniques are unstable due to near-end speech and background noise, requiring complex step-size control algorithms and separate detection systems.
Innovation Solution
A low complexity algorithm computes step sizes using power spectral density functions of error and far-end signals, eliminating the need for single talk/double talk detectors and voice activity detectors, and stabilizing the adaptive filter by controlling the step size μ in the partitioned block frequency domain adaptive filter (PBFDAF) for effective echo cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If partitioned block frequency domain adaptive filter (PBFDAF) is used to reduce computational complexity, then computational complexity is reduced, but delay increases due to filter length
Solution Approach 1:
The patent implements dynamic step-size control where the step-size parameter μ is continuously adapted based on signal conditions (double-talk detection, noise levels). This allows the filter to optimize its convergence speed and stability in real-time, effectively managing the trade-off between delay and complexity by adjusting adaptation rate dynamically rather than using fixed parameters
Solution Approach 2:
The patent changes key operational parameters including step-size μ, block length, and filter length based on signal conditions. By dynamically adjusting these parameters, the system can reduce delay when conditions permit while maintaining computational efficiency, resolving the contradiction between fixed parameter constraints and performance optimization
2Ease of operation
If fixed step size is used in adaptive filter, then operation is simple, but stability deteriorates in presence of near-end speech and background noise
Solution Approach 1:
The patent transitions from fixed to dynamic step-size control where μ is continuously adjusted based on double-talk detection algorithms and noise level estimation. This dynamic adaptation maintains filter stability under varying acoustic conditions while preserving operational simplicity through automated control, eliminating the need for manual parameter tuning
Solution Approach 2:
The patent implements feedback mechanisms where the adaptive filter monitors signal conditions (near-end speech detection, noise levels) and uses this information to adjust the step-size μ in real-time. This closed-loop control ensures stability during double-talk and noisy conditions while maintaining simplicity through algorithmic automation rather than complex external control systems
3Reliability
If separate detection algorithms and background noise estimators are added to handle noisy conditions, then reliability improves, but device complexity increases
Solution Approach 1:
The patent merges multiple functions (echo cancellation, double-talk detection, noise estimation, step-size control) into a single integrated adaptive filter system. The step-size control algorithm simultaneously performs stability control, double-talk detection, and noise adaptation, eliminating the need for separate detection algorithms and background noise estimators while maintaining reliability through unified processing
Solution Approach 2:
The patent creates a universal step-size control algorithm that performs multiple functions: stability control during echo suppression, double-talk detection, and noise level adaptation. This multi-functional approach improves reliability across diverse acoustic conditions without increasing device complexity, as the same algorithmic framework handles all detection and control tasks
Data Source
AI summary
A novel technique for canceling echo signal in teleconferencing applications. In one example embodiment, a low complexity double-talk and noise robust frequency domain adaptive filter is used to cancel the echo signal during the teleconferencing applications. The adaptive filter computes step sizes using power spectral density functions of error and far end signals using an equation, which does not require a single talk/double detectors and a voice activity detector. The computed step sizes are then used by the adaptive filter (PBFDAF) to cancel the echo signal.