Frequency-Domain Echo and Crosstalk Cancellation With One FFT Engine
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Solution Overview
Problem
Existing communications systems, such as 10GBase-T Ethernet, face challenges in accurately canceling echo and crosstalk noise, which affect the accuracy of communications.
Innovation Solution
The use of frequency domain adaptive filters, specifically employing a Fast Fourier Transform engine, to buffer and convert data from each transmit channel, calculate correction signals based on correlations between error signals and data, and apply these corrections to reduce echo and crosstalk across multi-channel and full-duplex systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple frequency domain transform engines are used to process all channels simultaneously, then the echo and crosstalk cancellation accuracy is improved, but the power consumption and chip area increase
Solution Approach 1:
The patent divides the frequency domain processing into two distinct stages: a first frequency domain transform that processes transmit signals to generate expected crosstalk and echo, and a second frequency domain transform that processes received signals to generate actual crosstalk and echo. This segmentation allows the system to use a single transform engine sequentially for both operations, reducing power consumption and area while maintaining cancellation accuracy through adaptive coefficient adjustment between stages.
2Measurement precision
If multiple frequency domain transform engines are used to process all channels simultaneously, then the echo and crosstalk cancellation accuracy is improved, but the chip area increases
Solution Approach 1:
The patent implements a single frequency domain transform engine that performs multiple functions: it processes transmit channel signals to generate expected crosstalk and echo, and subsequently processes received channel signals to generate actual crosstalk and echo. This multi-functional approach eliminates the need for separate transform engines for each operation, significantly reducing chip area while maintaining the mathematical accuracy of echo and crosstalk cancellation through proper coefficient adaptation.
3Use of energy by moving object
If a single frequency domain transform engine is used for all calculations, then power and area are saved, but the computational complexity increases
Solution Approach 1:
The patent performs preliminary processing by first generating expected crosstalk and echo from transmit signals using the single transform engine, then uses these expected values to guide the subsequent processing of received signals. The adaptation of crosstalk and echo coefficients based on the difference between expected and actual values simplifies the overall computational complexity while maintaining accuracy, as the system leverages prior knowledge from the first transform operation to inform the second operation.
Data Source
AI summary
Combined echo and crosstalk cancellation is provided. Frequency domain adaptive filters are used to remove or reduce the effects of echo and crosstalk for a multi-channel and full-duplex communications system. Data from each transmit channel is buffered and converted to the frequency domain. The frequency domain data is multiplied by crosstalk coefficients to obtain a frequency domain correction signal for each channel. Adaptation of the crosstalk coefficients is based on correlations between the error signals and the data from each of the transmit channels. A single frequency domain transform engine, such as a Fast Fourier Transform engine, is employed for all calculations to save power and area.