Dynamic Step Size Control for Acoustic Echo Cancellation
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Solution Overview
Problem
Existing acoustic echo cancellers (AEC) face performance issues due to unpredictable convergence times, leading to poor echo removal in varying environments, as current step size control schemes assume fixed convergence periods, which may not align with actual adaptation needs.
Innovation Solution
A step size controller that dynamically adjusts the adaptation rate by monitoring relationships between adaptive coefficients, using a convergence factor to determine when the AEC has converged, allowing for more precise control of the adaptation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a large step size is used during the fixed convergence period, then the AEC coefficients converge quickly, but the system becomes susceptible to disruptive inputs like background noise and double talk
Solution Approach 1:
The patent implements dynamic step size control by continuously monitoring the energy of the echo signal and adapting the step size parameter in real-time. During initial convergence, the step size is larger to accelerate adaptation, but automatically reduces when convergence is detected or disruptions occur, thereby resolving the contradiction between fast convergence and robustness to disruptions
Solution Approach 2:
The system employs feedback mechanisms by monitoring the energy of the echo signal and using this information to adjust the step size parameter. This closed-loop control allows the system to detect convergence status and adapt to disruptive inputs, maintaining reliability while achieving rapid convergence when appropriate
2Reliability
If a small step size is used after convergence, then the system becomes less susceptible to disruptive inputs, but the convergence process takes longer
Solution Approach 1:
The step size parameter transitions dynamically from large values during initial convergence to small values after convergence is detected. This time-varying parameter control ensures rapid initial convergence while maintaining stability and robustness in the steady state, effectively resolving the time-reliability trade-off
Solution Approach 2:
The system prepares for potential disruptions by having a mechanism ready to reduce step size when convergence is detected or when disruptive inputs are sensed. This preliminary preparation ensures that the system can quickly transition to a robust operating mode without suffering from prolonged exposure to disruptions
3Ease of manufacture
If a fixed convergence period is assumed, then the step size control scheme is simple to implement, but poor AEC performance occurs when convergence does not align with the fixed period
Solution Approach 1:
The system performs self-diagnosis by monitoring the energy of the echo signal and automatically detecting when convergence has occurred. This self-service capability eliminates the need for manual tuning of fixed convergence periods and allows the system to adapt to varying acoustic environments, maintaining high performance without complex implementation
Solution Approach 2:
The patent changes the operational parameters of the AEC system dynamically based on the detected convergence status. By monitoring echo energy and adjusting the step size parameter accordingly, the system adapts to different acoustic environments and convergence patterns, resolving the contradiction between simple fixed-period control and reliable performance across varying conditions
Data Source
AI summary
A step size controller may be used to control the rate of adaptation in an acoustic echo canceller. Step size control based on the values of adaptive coefficients (rather than, e.g., a fixed initial adaptation period) provides improved reliability and resistance to disruption. Accordingly, features are disclosed for controlling step size based on the values of adaptive coefficients.