Co-located Transmitter Receiver Interference Cancellation
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Solution Overview
Problem
Co-located radio communication systems experience interference due to intense signals from nearby transmitters, leading to receiver desensitization and broadband noise, which existing solutions like RF filters and analog subtraction methods are unable to effectively address, especially when transmitters and receivers share frequency bands or have non-linearities in their amplification chains.
Innovation Solution
A device and method that combine analog and digital corrections to reduce interference, using a coupler to take a reference signal after the transmitter's amplification chain, modify its amplitude and phase for analog correction, and then digitize it for digital processing to eliminate residual interference, accounting for distortions introduced by both analog and digital processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If RF filters are used to reduce interfering signal intensity, then interference is reduced, but insertion losses reduce the power of the transmitted signal and sensitivity of the receiving equipment
Solution Approach 1:
The patent extracts the interfering signal component from the received signal by generating a reference signal that replicates the interfering signal characteristics. This reference signal is then subtracted from the received signal to remove the interference without requiring RF filters that would cause insertion losses.
Solution Approach 2:
The patent introduces a reference signal as an intermediary element that mediates between the interfering signal and the useful signal. This reference signal serves as a template for identifying and removing the interfering component through subtraction, avoiding the need for passive filtering components that introduce losses.
2Reliability
If analog subtraction method is used to eliminate interfering signal, then receiver desensitization is avoided, but the method is only effective if the analog copy is sufficiently synchronized and cannot account for distortions introduced by analog processing circuit
Solution Approach 1:
The patent replaces the analog processing circuit with a digital signal processing system. The interfering signal reference is captured and processed in the digital domain, allowing for precise synchronization and distortion compensation through digital algorithms rather than analog circuitry, which is prone to synchronization errors and nonlinear distortions.
Solution Approach 2:
The patent changes the domain parameter from analog to digital, enabling precise control and measurement of signal parameters such as phase, frequency, and amplitude. This digital representation allows for accurate synchronization and compensation of distortions that cannot be achieved with analog processing alone.
3Adaptability or versatility
If digital processing is applied to eliminate interference, then complex operations can be performed, but the reference signal taken before analog conversion cannot account for non-linearities of the amplification chain
Solution Approach 1:
The patent captures the reference signal at an early stage in the signal chain, before it passes through the power amplifier's non-linear region. By taking the reference signal from a point where the amplification is still linear, the system can accurately model and compensate for the interfering signal characteristics without being corrupted by non-linear distortions.
Solution Approach 2:
The patent creates an accurate copy of the interfering signal by tapping the reference signal from the transmitter output. This copy is then processed digitally to match the characteristics of the interfering signal as it appears at the receiver, enabling precise subtraction even in the presence of non-linearities in the power amplifier.
4Productivity
If transmitter and receiver share the same frequency band, then spectrum efficiency is improved, but interference between the two devices increases significantly
Solution Approach 1:
The patent converts the harmful self-interference signal into a useful reference signal. By capturing and processing the transmitted signal as a reference, the system transforms the interfering component into a tool for its own elimination, enabling full-duplex operation where transmission and reception occur simultaneously on the same frequency without mutual interference.
Data Source
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AI summary
The device (1) for processing a signal received (R) by a receiver (RE) disturbed by a transmitter (EM), said transmitters (EM) and receiver (RE) being co-located, comprises: • a first coupler (10) configured to take a first reference signal (Ref1); • an analog processing circuit (20) of the first reference signal (Ref1); • a second coupler (40) configured to combine the modified reference signal (Ref2) with the signal received (R) by an antenna of the receiver; • a first analog-to-digital conversion module (401) digitizing the first reference signal (Ref1); • the second analog-to-digital conversion module (402) digitizing the combined signal (R2) in order to deliver a combined digital signal (R2n) to the digital signal processing device (50), said signal processing device (50) delivering a resulting digital signal (Run) to an information processing module (60) of the receiving equipment (RE).