Harmonic Signal Cancellation in Single-Antenna Carrier Aggregation
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Solution Overview
Problem
When using a single antenna for carrier aggregation, transmission signals on one communication band can interfere with reception signals on another band, leading to deterioration in signal-to-noise (S/N) ratio, especially when harmonic frequencies overlap.
Innovation Solution
A transmission-reception device is designed with a first and second RF circuit, an antenna, and an antenna duplexer, along with a demultiplexer, sensing unit, control unit, and signal adjusting unit, which demultiplexes and adjusts the harmonic signals to cancel interference, ensuring precise detection and adjustment of amplitude and phase to prevent harmonic signal leakage into the reception circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a single antenna is used for carrier aggregation to reduce device size, then device size is reduced, but transmission signals on one communication band interfere with reception signals on another band, deteriorating S/N ratio
Solution Approach 1:
The patent segments the signal processing path by introducing a demultiplexer that separates the transmission signal into fundamental wave and harmonic signal components. This segmentation allows independent processing and cancellation of harmful harmonic signals that cause interference to reception signals on other bands, thereby resolving the S/N ratio deterioration while maintaining single-antenna operation.
Solution Approach 2:
The patent converts the harmful harmonic signals (which cause interference) into beneficial canceling signals. By detecting the harmonic signals, adjusting their amplitude and phase, and adding them back to the transmission path with opposite phase, the system transforms the harmful interference into a useful cancellation mechanism that protects the reception signal quality.
2Reliability
If multiple antennas are provided to avoid interference, then S/N ratio is maintained, but device size increases
Solution Approach 1:
The patent makes the single antenna serve multiple functions: it handles both transmission on the first communication band and reception on the second communication band simultaneously. By combining signal cancellation technology with the antenna, the system achieves multi-band operation without requiring separate antennas for each function, thus avoiding device size increase.
3Adaptability or versatility
If harmonic frequency band of transmission signal overlaps with reception signal band, then communication flexibility is improved, but S/N ratio deteriorates due to interference
Solution Approach 1:
The patent implements a feedback mechanism where the harmonic signal generated by the transmission circuit is detected, its characteristics are measured, and then a canceling signal is generated based on this feedback. The canceling signal is adjusted according to the detected harmonic signal's amplitude and phase, creating a closed-loop system that continuously compensates for interference even when frequency bands overlap.
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
This configuration effectively restricts the deterioration of the S/N ratio during carrier aggregation, allowing simultaneous transmission and reception on multiple bands without degrading the quality of the reception signal.
Implementation Method 1
The antenna duplexer is connected between the antenna and the first and second RF circuits, transfers the transmission signal from the first RF circuit to the antenna, and transfers the reception signal from the antenna to the second RF circuit
Implementation Method 2
The signal adjusting unit adjusts at least one of an amplitude and a phase of a harmonic signal demultiplexed by the demultiplexer, on the basis of the adjustment coefficient
Implementation Method 3
The demultiplexer demultiplexes the transmission signal on the first communication band
Implementation Method 4
the harmonic signal of the transmission signal output from the first RF circuit is canceled with the harmonic signal which is demultiplexed by the demultiplexer and the amplitude and phase of which are adjusted by the signal adjusting unit
Data Source
AI summary
A transmission-reception device includes an antenna duplexer, an antenna, and first and second transmission-reception circuits. A demultiplexer is connected between the first transmission-reception circuit and the antenna duplexer, and a multiplexer is connected between the second transmission-reception circuit and the antenna duplexer. A signal adjusting unit is connected between the demultiplexer and the multiplexer. The amplitude and phase of a third harmonic signal of a first transmission signal reflected by the antenna are detected. The signal adjusting unit adjusts the amplitude and phase of the third harmonic signal demultiplexed by the demultiplexer on the basis of the detection results, and outputs a cancel signal. The multiplexer synthesizes and hence cancels the third harmonic signal reflected by the antenna and the cancel signal with each other.