Communication Device Antenna Matching for Self-Interference Cancellation
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Solution Overview
Problem
Self-interference signals caused by variations in antenna impedance due to changes in the surrounding environment degrade communication quality in communication devices sharing an antenna for transmission and reception, as existing cancellation methods are inadequate in adjusting to these variations.
Innovation Solution
A communication device equipped with an antenna, first and second generation units, a suppression unit, detection units, and an adjustment unit to dynamically adjust antenna impedance and generate a cancel signal to effectively cancel self-interference signals, using a matching adjustment unit with multiple matching circuits to maintain impedance matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cancel signal is adjusted based on the transmitted signal to cancel the self-interference signal, then the self-interference signal can be cancelled under stable conditions, but the cancellation becomes ineffective when antenna impedance varies due to environmental changes
Solution Approach 1:
The patent applies dynamics by transitioning from a static cancel signal adjustment to a dynamic adjustment mechanism. The reception system now includes an adjustment unit that continuously adapts the cancel signal parameters (amplitude and phase) based on real-time detection of self-interference signal characteristics. This dynamic adaptation allows the system to maintain effective cancellation despite environmental changes causing antenna impedance variations.
Solution Approach 2:
The patent implements feedback by creating a closed-loop control system. The detection unit monitors the self-interference signal characteristics, and this information is fed back to the adjustment unit, which modifies the cancel signal accordingly. This feedback mechanism enables the system to automatically compensate for impedance variations and maintain optimal cancellation performance under varying conditions.
2Measurement precision
If the reception system gain is increased to improve sensitivity for receiving weak response signals, then reception sensitivity is improved, but the system becomes saturated by the strong self-interference signal
Solution Approach 1:
The patent applies preliminary anti-action by generating and subtracting the cancel signal before the reception system processes the received signal. By removing the self-interference component in advance through signal subtraction, the system prevents saturation from occurring in the subsequent reception stages, thereby enabling high-gain operation without saturation risks.
Solution Approach 2:
The patent converts the harmful self-interference signal into a beneficial cancellation mechanism. By detecting the self-interference signal characteristics and generating a corresponding cancel signal with opposite phase, the system transforms the harmful interference into a useful tool for noise reduction, allowing the reception system to operate at high sensitivity without saturation.
3Ease of operation
If a single cancel signal adjustment is performed before receiving response signals, then the self-interference signal can be cancelled initially, but the cancellation becomes inaccurate when environmental conditions change during operation
Solution Approach 1:
The patent ensures continuity of useful action by implementing continuous adjustment of the cancel signal during operation. Rather than performing a single adjustment before reception, the system continuously monitors self-interference characteristics and updates the cancel signal parameters in real-time, ensuring sustained cancellation accuracy throughout the operational period despite environmental variations.
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
The device ensures effective cancellation of self-interference signals even with varying antenna impedance, maintaining communication quality by dynamically adjusting impedance and generating appropriate cancel signals, thereby reducing noise and saturation in the reception system.
Implementation Method 1
a second generation unit that generates a cancel signal by changing an amplitude and a phase of the carrier wave generated by the first generation unit
Implementation Method 2
a suppression unit that suppresses a self-interference signal in an output signal from the output terminal by using the cancel signal generated by the second generation unit
Data Source
AI summary
A communication device includes an antenna; a first generation unit; a duplexer; a second generation unit; a suppression unit; a first detection unit; and an adjustment unit. The duplexer receives the carrier wave generated by the first generation unit from an input terminal and outputs the carrier wave to the antenna from an input and output terminal, and outputs a signal input from the antenna to the input and output terminal from an output terminal. The second generation unit generates a cancel signal by changing an amplitude and a phase of the carrier wave. The suppression unit suppresses a self-interference signal in an output signal from the output terminal by using the cancel signal. The first detection unit detects a mismatching state of impedance matching related to the antenna. The adjustment unit adjusts, in response to detection of the mismatching state, an antenna impedance to eliminate the mismatching state.