Transceiver Nonlinear Echo Cancellation for Cleaner Receive Signals
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Solution Overview
Problem
High-speed Ethernet networks experience signal distortion due to non-linearities generated by transmit signals and echo cancellation, which are imposed on receive signals in full-duplex transmission, leading to additional distortion.
Innovation Solution
A method and apparatus that generate a non-linear replica signal of the transmit signal components imposed on the receive signal, using a non-linear filter to combine this replica with the receive signal, effectively canceling out the non-linearities introduced by the transmit signal DAC and echo cancellation signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If full-duplex transmission is implemented with shared transceiver circuitry, then transmission speed and bandwidth are improved, but non-linear distortion of receive signals worsens
Solution Approach 1:
The patent generates a non-linear replica signal that mimics the harmful non-linear distortion and subtracts it from the receive signal. This converts the harmful non-linear effect into a useful cancellation mechanism by creating and removing an identical copy of the distortion, thereby improving receive signal quality while maintaining full-duplex operation
Solution Approach 2:
The patent applies preliminary anti-action by generating the non-linear replica signal in advance and subtracting it from the receive signal before further processing. This preemptive cancellation prevents the non-linear distortion from affecting subsequent signal processing stages, resolving the contradiction between full-duplex speed and signal quality
2Object-affected harmful factors
If echo cancellation is applied to remove linear echo components, then echo interference is reduced, but non-linear distortion is introduced
Solution Approach 1:
The patent extracts and separates the non-linear distortion component from the receive signal by generating a dedicated non-linear replica signal. This extracted replica represents only the non-linear portion of the echo, allowing it to be cancelled independently without affecting the linear echo cancellation process, thus resolving the contradiction between echo removal and non-linear distortion introduction
3Device complexity
If transmit and receive sections share parallel circuitry, then device complexity is reduced, but non-linearities are imposed on receive signals
Solution Approach 1:
The patent introduces a non-linear replica signal generator as an intermediary component that mediates between the shared transmit circuitry and the receive signal processing. This intermediary creates a mathematical model of the non-linear distortion and uses it to cancel the harmful effects, allowing the shared circuitry architecture to be maintained while eliminating the negative impact of non-linearities
Data Source
AI summary
Embodiments of a method and apparatus for reducing non-linear transmit signal components of a receive signal of a transceiver signal are disclosed. The method includes the transceiver simultaneously transmitting a transmit signal, and receiving the receive signal. A non-linear replica signal of non-linear transmission signal components that are created in the transceiver by a transmit signal DAC, and imposed onto the receive signal, is generated. The non-linear replica signal is subtracted from the received signal reducing the non-linear transmission signal components imposed onto the receive signal.