Adaptive Coupling Equalization for Beamforming Echo Cancellation

Solution Overview

Problem

Existing beamforming-based communication systems, particularly sector-based systems, face challenges in efficiently integrating adaptive coupling equalization and acoustic echo cancellation, leading to poor echo cancellation and system performance degradation due to sudden changes in acoustic environments and varying echo characteristics.

Innovation Solution

The method involves combining coupling signals from active and inactive beamformers to equalize their responses using adaptive beamforming techniques, generating error signals to adaptively equalize inactive beamformers to the active beamformer's response, and applying acoustic echo cancellation to the active beamformer's output, allowing for rapid convergence and smooth transitions between beamformers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If beamforming coefficients change to adapt to new talker positions, then the system can accommodate different spatial areas, but the AEC algorithm must converge to very different cancellation coefficients each time, resulting in poor echo cancellation during transitions

Engineering Contradiction:

Improveability to accommodate different spatial areasVSAvoidecho cancellation performance during beamformer transitions

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies preliminary action by pre-equalizing the coupling response of inactive beamformers to match the active beamformer before switching occurs. This is achieved through adaptive filtering that adjusts the beamformer outputs to have consistent coupling characteristics, so when the look direction changes and a new beamformer becomes active, the AEC algorithm already has a familiar coupling response to work with, eliminating the need for complete re-convergence and maintaining reliable echo cancellation throughout transitions.

Inventive Principle:

Principle #10Preliminary action

2Device complexity

If a single acoustic echo canceller is placed at the output of the beamformer, then computational complexity is reduced, but the AEC algorithm struggles to adapt quickly when look direction or beamforming coefficients change

Engineering Contradiction:

Improvenumber of acoustic echo cancellersVSAvoidconvergence speed of AEC algorithm

Core Design Contradiction:

Device complexityVSSpeed

Solution Approach 1:

The patent applies preliminary action by pre-equalizing the coupling response of inactive beamformers to match the active beamformer before switching occurs. This is achieved through adaptive filtering that adjusts the beamformer outputs to have consistent coupling characteristics, so when the look direction changes and a new beamformer becomes active, the AEC algorithm already has a familiar coupling response to work with, eliminating the need for complete re-convergence and maintaining reliable echo cancellation throughout transitions.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent applies parameter changes by dynamically adjusting the beamforming coefficients of inactive beamformers to match the coupling characteristics of the active beamformer. This parameter adjustment occurs continuously through adaptive filtering, ensuring that when the system switches beamformers, the coupling parameters are already aligned, enabling the single AEC canceller to maintain fast convergence without requiring multiple parallel cancellers.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If adaptive beamforming is used to optimize source location and signal-to-noise ratio, then audio characteristics are optimized in changing environments, but the system becomes computationally intensive and suffers from robustness issues

Engineering Contradiction:

Improveaudio characteristics optimizationVSAvoidcomputational intensity and robustness

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies universality by creating a unified coupling equalization framework that serves multiple beamformers simultaneously. Instead of independently optimizing each beamformer (which would require multiple AEC cancellers and high computational complexity), the system uses a single AEC canceller that benefits from the pre-equalized coupling responses of all beamformers. This multi-functional approach maintains optimized audio characteristics while reducing computational intensity and improving robustness.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS7970123B2Adaptive coupling equalization in beamforming-based communication systems

Publication Date: 2011.06.28 MITEL CORP

AI summary

A method and system for rapid adaptive coupling equalization in beamforming-based communication systems, particularly sector-based beamforming systems, provides smooth transitions for AEC when the look direction of the communication system changes and when the acoustic environment varies with time. The coefficients of inactive beamformers are modified in real-time, using adaptive beamforming techniques based on the real-time loudspeaker-coupling signal, in order to force the outputs of inactive beamformers to have the same response to the loudspeaker coupling signal as the active beamformer does.