Multi-Radio Interference Cancellation with RF and Baseband Cancellers
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Solution Overview
Problem
Interference between radios in a multi-radio system, specifically due to gain drops and spurious spectrum components caused by an aggressor radio, leading to out-of-band emissions and regulatory violations.
Innovation Solution
Implementing an RF canceller and a baseband canceller to generate and apply cancellation signals to the victim radio, adjusting phase and amplitude to cancel interference, and using a transmit nonlinearity model to further reduce spurious components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If time-division control is used to avoid interference between radios, then regulatory compliance is maintained, but system productivity and resource utilization are reduced
Solution Approach 1:
The patent converts the harmful interference signal from the aggressor radio into a useful cancellation signal. By capturing the aggressor's transmit signal and processing it through complex conjugation and amplitude scaling, the system creates an anti-phase signal that when combined with the victim radio's receive signal, cancels out the interference. This transforms the harmful interference into a beneficial cancellation mechanism, allowing simultaneous operation of multiple radios without violating regulatory requirements.
Solution Approach 2:
The patent introduces an intermediary cancellation signal generation mechanism between the aggressor and victim radios. The cancellation signal is generated by capturing the aggressor's transmit signal, processing it through complex conjugation and amplitude scaling based on channel estimates, and then combining it with the victim's receive signal. This intermediary process enables simultaneous radio operation while maintaining regulatory compliance.
2Productivity
If multiple radios operate simultaneously, then system productivity improves, but interference causing gain drops and saturation occurs
Solution Approach 1:
The patent applies preliminary anti-action by generating a cancellation signal before the interference affects the victim radio's receive signal. The system captures the aggressor's transmit signal, processes it through complex conjugation and amplitude scaling, and combines it with the victim's receive signal in advance. This preliminary cancellation prevents gain drops and saturation from occurring, enabling simultaneous multi-radio operation without performance degradation.
Solution Approach 2:
The patent implements feedback by using the victim radio's channel estimate of the aggressor signal to determine the appropriate amplitude scaling for the cancellation signal. The system continuously monitors the interference condition, adjusts the cancellation signal amplitude based on the measured channel characteristics, and applies it to cancel the interference. This feedback mechanism ensures effective cancellation while maintaining system stability.
3Duration of action of stationary object
If victim radio receives signal during aggressor radio transmission, then communication continuity is maintained, but spurious spectrum components and out-of-band emissions increase
Solution Approach 1:
The patent converts the harmful spurious spectrum components and out-of-band emissions generated during simultaneous operation into a manageable interference signal. By capturing the aggressor's transmit signal and creating a complex conjugate cancellation signal, the system transforms the harmful nonlinear distortion products into a cancelable interference component. When the cancellation signal is applied, it reduces the spurious emissions and out-of-band emissions, allowing continuous communication while maintaining spectral compliance.
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
Effectively reduces interference, ensuring compliance with regulatory specifications and improving receiver sensitivity by minimizing gain drops and spurious emissions.
Implementation Method 1
The RF canceller generates an RF cancellation signal which is coupled to the victim radio. The RF cancellation signal has one or more of a phase and amplitude which cancels at an antenna of the victim radio a radio frequency (RF) transmit signal transmitted by the aggressor radio.
Implementation Method 2
the signal transmitted by the victim radio includes spurious spectrum components resulting from intermodulation with the signal transmitted by the aggressor radio
Data Source
AI summary
A multi-radio system comprises a first radio and a second radio co-located on the multi-radio system. The first radio is arranged to generate an RF transmit signal which is output by a first antenna of the first radio. In an example, the first radio comprises a radio frequency (RF) canceller arranged to output a RF cancellation signal which couples with the RF transmit signal received at a second antenna of the second radio. The RF cancellation signal that is output results in the cancellation of the RF transmit signal at the second antenna of the second radio.