Self-Interference Cancellation Using Phase Noise Reference
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Solution Overview
Problem
Current wireless full-duplex systems face challenges in effectively canceling self-interference, which affects the performance of signal reception due to significant phase noise on the radio frequency channel, limiting the efficiency of self-interference cancellation.
Innovation Solution
The proposed solution involves an apparatus and method that utilize a local oscillator to perform up-conversion and down-conversion processing on transmit and receive signals, respectively, with a self-interference canceller adjusting the baseband signals to cancel self-interference, effectively eliminating the impact of phase noise by using either the baseband transmit signal or a baseband reference signal generated from a radio frequency reference signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If digital interference cancellation is performed after down-conversion processing, then the self-interference cancellation can be implemented in the digital domain, but the performance is greatly affected by phase noise on the radio frequency channel
Solution Approach 1:
The patent performs down-conversion processing on both the receive signal and the reference signal before interference cancellation. By converting both signals to baseband in advance using the same local oscillator signal, the system establishes a common frequency reference that eliminates phase noise effects during the subsequent cancellation operation, thereby improving cancellation performance without significantly increasing system complexity
Solution Approach 2:
The patent introduces a reference signal that is generated by down-converting the transmit signal using the same local oscillator. This reference signal acts as an intermediary that carries the same phase noise characteristics as the self-interference component in the receive signal, allowing for accurate cancellation when the reference signal is subtracted from the receive signal in the digital domain
2Productivity
If wireless full-duplex technology is used to support simultaneous receiving and sending on the same radio channel, then spectral efficiency is doubled, but strong self-interference from transmit signal to receive signal must be avoided and canceled
Solution Approach 1:
The patent converts the harmful self-interference signal into a useful reference signal for cancellation. By down-converting the transmit signal using the same local oscillator that processes the receive signal, the system creates a reference signal that accurately represents the self-interference component. This reference signal is then subtracted from the receive signal in the digital domain, transforming the harmful interference into a beneficial cancellation mechanism that enables full-duplex operation
Solution Approach 2:
The patent implements a feedback mechanism where the transmit signal is captured, down-converted, and processed to generate a reference signal that is fed back to the receiver. This feedback loop allows the system to continuously track and cancel the self-interference component, enabling stable full-duplex operation by constantly removing the harmful feedback from transmit to receive path
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach improves the performance of self-interference cancellation by directly addressing phase noise, enhancing the spectral efficiency of wireless full-duplex systems by minimizing the energy of the target signal after cancellation.
Implementation Method 1
a first up-converter 130 is configured to acquire a baseband transmit signal, and perform up-conversion processing on the baseband transmit signal according to a local oscillator signal to generate a radio frequency transmit signal
Implementation Method 2
a first down-converter 150 is configured to acquire a radio frequency receive signal, and perform down-conversion processing on the radio frequency receive signal according to a local oscillator signal to acquire a baseband receive signal
Implementation Method 3
a self-interference canceller 190 is configured to perform self-interference cancellation processing on the baseband receive signal
Implementation Method 4
effectively eliminating the impact of phase noise by using either the baseband transmit signal or a baseband reference signal generated from a radio frequency reference signal
Data Source
AI summary
Embodiments of the present invention provide an apparatus for self-interference cancellation. The apparatus includes: a first splitter, configured to perform splitting processing on a local oscillator signal generated by a local oscillator to separately transmit the local oscillator signal to an up-converter and a delayer; the up-converter, configured to perform up-conversion processing on a baseband transmit signal according to the local oscillator signal to generate a transmit signal; the delayer, configured to perform delaying processing on the local oscillator signal according to a preset target delay; a first down-converter, configured to perform, based on the local oscillator signal obtained after the delaying processing, down-conversion processing on a receive signal to acquire a baseband receive signal, and transmit the baseband receive signal to a self-interference canceller; and the self-interference canceller, configured to perform self-interference cancellation processing on the baseband receive signal.