Self-Interference Cancellation in Microwave Transceivers
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Solution Overview
Problem
The existing microwave architecture faces challenges with low spectral efficiency and limited transmission bandwidth of intermediate frequency cables due to increased attenuation and interference from radio frequency bands like GSM/LTE, particularly when accelerating transmission bandwidth.
Innovation Solution
An interference cancellation method that involves sending a signal with a pilot and transmit component on different frequency bands, extracting jitter information, and reconstructing a self-interference signal to cancel it, allowing for partial or complete cancellation, thereby improving spectral efficiency and reducing cable losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the transmission bandwidth of the intermediate frequency cable is accelerated, then the spectral efficiency is improved, but the attenuation of the intermediate frequency cable increases
Solution Approach 1:
The patent changes the frequency parameter by using lower frequency bands for both transmit and receive signals instead of traditional high-frequency microwave bands. This parameter change reduces cable attenuation while maintaining spectral efficiency through the implemented interference cancellation technique that enables frequency reuse.
2Productivity
If the transmission bandwidth of the intermediate frequency cable is accelerated, then the transmission bandwidth is increased, but the interference from radio frequency bands increases
Solution Approach 1:
The patent converts the harmful self-interference signal into a beneficial element by using it as a reference for cancellation. The transmit signal that causes interference is captured, processed to extract channel characteristics, and then used to generate an anti-phase cancellation signal that eliminates the interference, thereby enabling frequency reuse and increasing transmission bandwidth.
Solution Approach 2:
The patent implements a feedback mechanism where the transmit signal is captured at the receive end, processed to determine channel impulse response and phase information, and then fed back to generate a cancellation signal. This closed-loop feedback system continuously compensates for self-interference, allowing the system to operate with overlapping transmit and receive frequency bands.
3Object-affected harmful factors
If frequency-division duplexing is used to resolve interference, then interference is reduced, but spectral efficiency decreases
Solution Approach 1:
The patent merges the transmit and receive frequency bands by allowing them to overlap or be identical, breaking the traditional separation imposed by FDD. Through interference cancellation, the system combines the benefits of frequency division (interference management) with frequency reuse (spectral efficiency), enabling both transmit and receive to operate in the same or adjacent frequency bands simultaneously.
Data Source
AI summary
A method includes: A first device sends a first signal to a second device, where the first signal includes a first transmit signal and a first pilot signal; the first device obtains a second signal, where the second signal includes a first self-interference signal, a second pilot signal, and a second receive signal from the second device; the first device extracts jitter information of the first self-interference signal based on the first pilot signal and the second pilot signal; the first device reconstructs a self-interference signal based on the first transmit signal and the jitter information of the first self-interference signal, to obtain a cancellation signal of the first self-interference signal; and the first device cancels the first self-interference signal from the second receive signal based on the cancellation signal of the first self-interference signal.