IF Self-Interference Cancellation for Frequency-Dependent Full-Duplex Radio
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Solution Overview
Problem
Full-duplex wireless communication systems face challenges with self-interference, particularly in frequency-dependent environments, where existing analog self-interference cancellation methods are less effective, limiting their spectral efficiency and performance.
Innovation Solution
A system and method for frequency-independent analog self-interference cancellation using a tunable filter-based approach in the intermediate-frequency domain, which includes a transmit coupler, receive coupler, downconverter, upconverter, and IF analog self-interference canceller, enabling effective cancellation across multiple frequency bands by modeling self-interference in each band section and combining accurate self-interference signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional analog self-interference cancellation methods are used, then device complexity is reduced, but self-interference cancellation performance deteriorates in frequency-dependent environments
Solution Approach 1:
The patent introduces an intermediate frequency (IF) domain as a mediator between the RF transmit and receive signals. By downconverting RF signals to IF, processing the self-interference cancellation in the IF domain, and then upconverting back to RF, the system achieves frequency-independent cancellation performance without requiring complex frequency-specific analog circuits at RF frequencies.
Solution Approach 2:
The patent replaces the traditional mechanical/analog frequency-selective filtering approach with a signal processing approach in the IF domain. Instead of using complex frequency-dependent analog cancellation circuits, the system uses digital signal processing techniques in the IF domain to model and cancel self-interference, achieving frequency independence.
2Productivity
If full-duplex wireless communication is implemented, then spectral efficiency is improved, but self-interference increases
Solution Approach 1:
The patent applies preliminary anti-action by proactively generating a model of the self-interference signal before it corrupts the received signal. The system downconverts the transmit signal to IF, models the self-interference characteristics in the IF domain, and subtracts this modeled interference from the received signal, preventing the harmful effects of self-interference from degrading communication performance.
Solution Approach 2:
The patent extracts the self-interference component from the received signal by first downconverting to IF, where the self-interference can be easily modeled and separated. The system extracts the transmit signal component at IF, processes it to model the self-interference, and then removes this extracted interference model from the received signal to recover the desired communication signal.
Data Source
AI summary
A system and method for analog self-interference cancellation that includes receiving an RF transmit signal of a full-duplex radio; frequency downconverting the RF transmit signal to an IF transmit signal; transforming the IF transmit signal into an IF self-interference signal using an IF analog self-interference cancelling circuit; frequency upconverting the IF self-interference signal to an RF self-interference signal; and combining the RF self-interference signal with an RF receive signal of the full-duplex radio.