Signal Canceller with Adaptive Nonlinear RF Interference Modeling
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Solution Overview
Problem
Current RF transceiver systems face challenges in achieving simultaneous transmit and receive operations due to self-interference and external interference, particularly from nonlinear distortion and frequency-dependent amplitude and phase transfer functions, which are not adequately addressed by existing cancellation techniques.
Innovation Solution
A multi-layered cancellation approach using digitally assisted analog cancellation with linear and nonlinear modeling, combined with digital blind source separation, to accurately represent the RF transmit chain's transfer function and effectively cancel interference, including self-interference and external interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional fixed models are used for self-interference cancellation, then the system is simpler, but the cancellation accuracy is insufficient due to not accounting for frequency dependent amplitude and phase transfer function and nonlinear distortion
Solution Approach 1:
The patent applies dynamics by transitioning from fixed models to adaptive models that continuously track the frequency-dependent amplitude and phase transfer function. The system uses adaptive filtering techniques to update cancellation coefficients in real-time, allowing the model to dynamically accommodate changes in the RF transmit chain characteristics over frequency and time.
Solution Approach 2:
The patent implements parameter changes by modeling the frequency-dependent characteristics of the RF transmit chain through varying cancellation coefficients. The system adjusts these parameters across different frequency bins to accurately represent the transfer function, enabling precise cancellation despite frequency variations and nonlinear distortion.
2Object-affected harmful factors
If nonlinear distortion is not compensated, then the system is simpler, but the interference rejection level is limited due to spectral spreading and intermodulation distortion
Solution Approach 1:
The patent converts the harmful nonlinear distortion into a beneficial cancellation mechanism by measuring the distortion characteristics of the RF transmit chain and using them to generate compensating signals. The system models the nonlinearities (spectral spreading, intermodulation distortion) and creates opposite-phase signals to cancel these distortion components, effectively turning the distortion problem into a solvable signal processing task.
3Productivity
If wideband cancellation is implemented, then the system throughput is improved, but the processing requirements increase due to the need to handle multiple frequency components simultaneously
Solution Approach 1:
The patent applies segmentation by dividing the wideband cancellation task into multiple narrower frequency bins. Instead of processing the entire wideband signal as a single unit, the system segments the spectrum and processes each frequency bin independently using adaptive filtering. This approach reduces the complexity within each bin while maintaining overall wideband coverage, enabling efficient handling of multiple frequency components simultaneously.
Data Source
AI summary
The present invention is an architecture and method for radio frequency (RF) simultaneous transmit and receive applications that uses linear and nonlinear modeling to generate a very accurate, wideband analog signal that cancels self-interference before it is digitized by the receiver. In addition to this digitally assisted analog cancellation, another layer of signal cancellation is provided with digital blind source separation. Adaptive signal processing continuously monitors the level of cancellation and updates the processing to provide optimal performance in changing conditions (e.g., rapidly changing frequency content, signal power, temperature, etc.). Signal cancellation can be performed on extremely broadband signals providing high levels of cancellation, enabling a full-duplex RF transceiver. Furthermore, the present invention optionally includes an external signal canceller for cancelling unknown interference such as jamming.