LOW-RESOURCE DELAYLESS SUBBAND ADAPTIVE FILTER USING WEIGHTED OVERLAP-ADD
A delayless structure targeted for low-resource implementation is proposed to eliminate filterbank processing delays in subband adaptive filters (SAFs). Rather than using direct IFFT or polyphase filterbanks to transform the SAFs back into the time-domain, the proposed method utilizes a weighted overlap-add (WOLA) synthesis. Low-resource real-time implementations are targeted and as such do not involve long (as long as the echo plant) FFT or IFFT operations. Also, the proposed approach facilitates time distribution of the adaptive filter reconstruction calculations crucial for efficient real-time and hardware implementation. The method is implemented on an oversampled WOLA filterbank employed as part of an echo cancellation application. Evaluation results demonstrate that the proposed implementation outperforms conventional SAF systems since the signals used in actual adaptive filtering are not distorted by filterbank aliasing. The method is a good match for partial update adaptive algorithms since segments of the time-domain adaptive filter are sequentially reconstructed and updated.
Summary
This 2010 paper introduces a delayless subband adaptive filter architecture that uses weighted overlap-add (WOLA) synthesis to remove filterbank-induced processing delays while keeping computational and memory requirements low. Readers will learn how the WOLA‑based reconstruction and time-distributed adaptive filter calculations enable real-time, low‑resource implementations (demonstrated for echo cancellation) without long FFT/IFFT operations.
Key Takeaways
- Explain how WOLA synthesis can replace IFFT/polyphase synthesis to eliminate filterbank reconstruction delay in subband adaptive filters
- Show how to avoid long FFT/IFFT operations to reduce memory and compute in low-resource real-time implementations
- Demonstrate time-distributed reconstruction of adaptive filter outputs to enable efficient hardware and real-time scheduling
- Provide practical implementation guidance using an oversampled WOLA filterbank for echo cancellation and resource trade-offs
Who Should Read This
DSP engineers and researchers working on real-time audio/speech or echo-cancellation systems who need low-latency, low-resource subband adaptive-filter implementations.
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