Active Interference Cancellation for Radio Isolation
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Solution Overview
Problem
Compact electronic devices face challenges in achieving high isolation between coexisting radios operating in the same frequency band, leading to reduced operable range and data throughput due to interference, especially when traditional time-switched architectures are used.
Innovation Solution
The implementation of Active Interference Cancellation (AIC) techniques and RFFE circuitry, which allows simultaneous operation of multiple radios by copying and manipulating the aggressor's transmit signal to create destructive interference, thereby reducing unwanted signals at the victim receiver, and includes a power detector for impedance changes to maintain optimal isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional time-switched architectures are used to achieve isolation between radios, then interference between coexisting radios is reduced, but operable range and data throughput are reduced due to time-sharing limitations
Solution Approach 1:
The patent converts the harmful transmit signal from the first radio into a beneficial cancellation signal by copying it, adjusting its phase and amplitude, and injecting it into the receive path of the second radio. This transforms the interference problem into a solution where the aggressor's own signal becomes the tool for cancellation, enabling simultaneous operation of multiple radios without time-switching and thereby maintaining high data throughput while eliminating interference
Solution Approach 2:
The system performs preliminary action by proactively generating and injecting the cancellation signal before the interference degrades the receive signal quality. The AIC circuit continuously monitors and dynamically adjusts the cancellation signal parameters to preemptively counteract the interfering transmit signal, allowing both radios to operate simultaneously at full capacity without the need for time-sharing arbitration
2Object-affected harmful factors
If spatial separation is increased between radios to achieve isolation, then interference is reduced, but device compactness and cost-effectiveness are compromised
Solution Approach 1:
The patent replaces the mechanical/spatial isolation approach with an electrical signal processing solution. Instead of physically separating the radios in space (mechanical solution), the system uses electronic cancellation circuits to eliminate interference through signal manipulation. This substitution allows multiple radios to be placed in close proximity on the same PCB, maintaining compact device form factor while achieving the isolation效果 through electrical means rather than spatial separation
3Productivity
If simultaneous operation of multiple radios is enabled, then data throughput is increased, but interference between radios increases without AIC
Solution Approach 1:
The patent converts the harmful transmit signal from the first radio into a beneficial cancellation signal by copying it, adjusting its phase and amplitude, and injecting it into the receive path of the second radio. This transforms the interference problem into a solution where the aggressor's own signal becomes the tool for cancellation, enabling simultaneous operation of multiple radios without time-switching and thereby maintaining high data throughput while eliminating interference
Solution Approach 2:
The system implements feedback by continuously monitoring the receive signal quality and dynamically adjusting the cancellation signal parameters (phase, amplitude, delay) to maintain optimal interference cancellation. The AIC circuit uses feedback from the receive path to adaptively compensate for changes in the transmit signal characteristics, ensuring that simultaneous radio operation maintains high throughput without interference degradation
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
AIC enables radios to operate simultaneously with improved isolation, extending the operable range and increasing data throughput without the need for spatial separation, thus making compact devices both desirable and cost-effective.
Implementation Method 1
The adjusted RF signal is added to the second RF signal via the second RF coupler to remove from the second RF signal interference caused by the first RF signal
Data Source
AI summary
Antenna structures and methods of operating the same are described. One apparatus includes a processing device that executes an active interference cancellation (AIC) algorithm and radio frequency front-end (RFFE) circuitry coupled to the processing device. The RFFE circuitry includes two RF couplers, a fixed-delay filter, and an interference compensation circuit part of an electrical path between the two RF couplers. The AIC algorithm is operable to control the interference compensation circuit to adjust a phase, an amplitude or both of a copy of a first RF signal transmitted on a first antenna to remove corresponding interference in a second RF signal received at a second antenna that is caused by the first RF signal. The processing device triggers a re-calibration in the AIC algorithm when the digital values, received from a power detector circuit, indicate a change in impedance that exceeds a threshold.