Transceiver Echo Cancellation Using Segmented Drivers
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Solution Overview
Problem
High-speed Ethernet networks experience signal distortion due to the coupling of transmit signals with receive signals in full duplex transmission, leading to echo signals that introduce additional non-linearities and distortion, which existing methods struggle to effectively cancel.
Innovation Solution
The implementation of a transceiver system that generates echo and residual echo cancellation signals using dedicated DACs and drivers, allowing for the summation of these signals with the receive signal to reduce distortion, with separate drivers designed for optimal linear performance and additional residual DACs to decompose echo signals and improve cancellation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If full duplex transmission is implemented to enable simultaneous bidirectional communication, then network bandwidth and communication efficiency are improved, but transmit signal components couple back into receive signals creating echo signals that cause distortion
Solution Approach 1:
The echo cancellation process is segmented into multiple stages: first echo cancellation and second echo cancellation. Each stage uses separate cancellation signals generated by dedicated circuits (first echo cancellation signal generated by first canceller, second echo cancellation signal generated by second canceller). This segmentation allows progressive removal of echo components without overwhelming the receive signal with a single complex cancellation operation.
Solution Approach 2:
Dedicated echo cancellation circuits act as intermediary components between the transmit and receive paths. The first echo cancellation signal and second echo cancellation signal serve as mediator signals that are subtracted from the receive signal to remove echo components. These intermediary cancellation signals are generated by separate driver circuits that process the transmit signal to create appropriate cancellation waveforms.
2Object-affected harmful factors
If echo cancellation signals are generated and subtracted from receive signals to reduce distortion, then signal quality is improved, but the echo cancellation process itself introduces additional non-linearities and distortion
Solution Approach 1:
The echo cancellation function is divided into multiple independent cancellation stages, each with its own driver and subtraction circuit. The first echo cancellation signal is generated and subtracted in a first stage, then a second echo cancellation signal is generated and subtracted in a second stage. This segmentation distributes the cancellation operation across multiple linear stages rather than one complex non-linear stage.
Solution Approach 2:
The system changes the parameters of the cancellation process by using multiple cancellation signals with different characteristics rather than a single cancellation signal. The first and second echo cancellation signals have different amplitudes, phases, and frequency content, allowing the system to cancel echo across a broader frequency range while maintaining linearity in each individual cancellation stage.
3Object-affected harmful factors
If multiple echo cancellation signals are used to improve cancellation effectiveness, then echo reduction performance is improved, but device complexity and circuit requirements increase
Solution Approach 1:
The multiple echo cancellation functions are merged into a unified transceiver architecture where the first and second cancellers, drivers, and subtraction circuits work together as an integrated system. The transmit signal processing path is merged with the echo cancellation generation path, allowing the same transmit signal to be used for both transmission and generating cancellation signals without requiring separate signal sources.
Solution Approach 2:
The transceiver circuits are designed with multi-functionality: the same transmit signal is used for both data transmission and generating echo cancellation signals. The cancellation circuits serve dual purposes by processing the transmit signal to create cancellation waveforms that are then subtracted from the receive signal. This universality reduces the need for separate dedicated circuits for each function.
Data Source
AI summary
Embodiments of a method and apparatus of reducing transmit signal components of a receive signal of a transceiver are disclosed. One method includes generating a transmit signal by passing a pre-driver transmit signal through a transmit driver. An echo cancellation signal is generated by passing the pre-driver transmit signal through an echo cancellation driver. A residual echo signal is generated by passing a pre-driver residual echo cancellation signal through a residual echo cancellation driver. The transceiver simultaneously transmits the transmit signal, and receiving the receive signal. At least a portion of an echo signal of the receive signal is canceled by summing the echo cancellation signal with the receive signal. At least another portion of the cancellation echo signal of the receive signal is canceled by summing the residual echo cancellation signal with the receive signal.