Full-Duplex Wireline Interference Cancellation Using Analog Subtraction
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Solution Overview
Problem
Full-duplex communication systems face challenges in self-interference (SI) and echo cancellation, particularly in high-speed or long-distance links, where existing solutions require complex and power-consuming high dynamic range analog to digital converters (ADCs) and struggle with adjusting weight coefficients, especially when the remote terminal is transmitting simultaneously.
Innovation Solution
A system comprising self-interference (SI) and echo canceller modules, configured to operate in the analog domain, using delay elements, multipliers with adjustable weight coefficients, and correlators to subtract SI and echo from received signals, with a residual cancellation module in the digital domain to handle remaining interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high dynamic range ADCs are used for SI and echo cancellation in higher-speed or longer distance full-duplex links, then cancellation performance is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent replaces the conventional ADC-based digital domain cancellation approach with an analog domain cancellation system using hybrid transformers and analog subtractors. This substitution eliminates the need for high dynamic range ADCs while maintaining cancellation performance, thereby reducing device complexity and power consumption.
Solution Approach 2:
The patent introduces hybrid transformers as intermediary components that couple the transmit and receive paths. These transformers provide magnetic coupling that enables analog SI and echo cancellation through subtractive combining of signals, serving as a mediator between the transmitter and receiver to achieve cancellation without complex digital processing.
2Use of energy by stationary object
If adaptive SI/echo cancellers are used to cancel interference in analog domain, then power consumption is reduced, but weight coefficient adjustment becomes challenging when remote terminal transmits simultaneously
Solution Approach 1:
The patent employs training sequences transmitted during initialization to pre-adjust the weight coefficients of the adaptive filters before normal bidirectional communication begins. This preliminary action ensures that the cancellers are properly configured before simultaneous transmission occurs, eliminating the tuning challenge during operation.
Solution Approach 2:
The patent uses feedback mechanisms where the received signal is processed through adaptive filters with adjustable weight coefficients, and the filtered signal is subtracted from the original received signal. The system continuously adapts the coefficients based on the error signal to optimize cancellation performance, enabling automatic tuning without manual intervention.
3Measurement precision
If multiple delayed and weighted copies of transmitted signal are subtracted from received signal, then echo and SI cancellation is achieved, but system complexity increases due to multiple delay elements and weight adjustments
Solution Approach 1:
The patent uses hybrid transformers that perform multiple functions: they provide magnetic coupling for signal transmission, enable analog SI cancellation through their coupling characteristics, and facilitate echo cancellation through the same magnetic coupling mechanism. This multi-functionality reduces the need for separate components for each cancellation function, thereby simplifying the overall system structure.
Solution Approach 2:
The patent combines the SI cancellation and echo cancellation functions into a unified analog domain processing structure. Both cancellation operations are performed simultaneously using the same hybrid transformer coupling and analog subtractor circuitry, merging what would traditionally require separate processing paths into a single integrated system.
Data Source
AI summary
The present invention relates to a system for cancelling interference in a full-duplex wireline communication link. The communication link has a transceiver at each end and configured to transmit a signal and receive a signal. The transceiver comprises: a self-interference (SI) canceller module configured to subtract self-interference of the signal transmitted by the transceiver from the signal received by the same transceiver in analog domain; and an echo canceller module configured to subtract reflected version of the signal transmitted by the transceiver from the signal received by the same transceiver in analog domain.