Passive Intermodulation Cancellation via Nonlinear Prediction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In radio-frequency communication systems, especially frequency-division duplex systems, the non-linear characteristics of circuit components cause distortion components of the transmitted signal to 'leak' into the received signal, affecting the error rate and signal quality, despite existing predistortion methods not fully mitigating these effects.
Innovation Solution
A method is introduced to enhance the received signal by using a non-linear predictor to identify and remove distortion components from the received signal, involving upsampled reference and received signals, correlation to determine relative delay, and adaptive predictor parameters to synchronize and cancel distortion signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If predistortion is applied to mitigate leakage, then some distortion is reduced, but the error rate and signal quality remain adversely affected
Solution Approach 1:
The patent converts the harmful distortion components into beneficial information by using the transmitted signal itself (which contains the distortion) as a reference to predict and cancel the distortion in the received signal. The distortion that was previously purely harmful is now utilized as a reference for cancellation.
Solution Approach 2:
The patent implements feedback by using the transmitted signal as a reference input to a non-linear predictor, which then generates distortion components that are fed back into the received signal for cancellation. This closed-loop approach continuously refines the distortion estimation and removal.
2Productivity
If frequency-division duplex is used to enable simultaneous transmission and reception, then communication efficiency is improved, but distortion components leak from transmit to receive path
Solution Approach 1:
The patent introduces an intermediary signal processing chain consisting of a non-linear predictor and distortion canceller that mediates between the transmitted signal and the received signal. This intermediary process predicts the distortion components and removes them, enabling the FDD system to operate efficiently without signal leakage interference.
3Ease of operation
If non-linear characteristics of circuit components are present, then signal processing capability is maintained, but distortion components are generated and leaked into the received signal
Solution Approach 1:
The patent changes the parameter of signal representation by transforming signals into an upsampled domain with a common sampling rate. This parameter change enables more accurate correlation and distortion prediction. The upsampling process creates a finer-grained representation that captures distortion characteristics more effectively.
Data Source
AI summary
A received signal is enhanced by removing distortion components of a concurrently transmitted signal. A received signal is acquired in a receive frequency band concurrently with transmission of a transmit signal in a transmit frequency band. The received signal includes an intermodulation distortion component of the transmit signal. A representation of the transmit signal is processed using a non-linear predictor to output a distortion signal representing predicted distortion components in the received signal. The received signal is enhanced using the distortion signal by removing the predicted distortion components from the received signal corresponding to the distortion signal.