Antenna Calibration Apparatus Using Interference Cancellation
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Solution Overview
Problem
Antenna calibration in RF transceivers is hindered by external interferences from the Antenna Reference Point, which degrades beamforming performance due to limited Signal to Interference and Noise Ratio (SINR), particularly in low power stations where spurious emissions and mutual antenna leakage are significant.
Innovation Solution
The apparatus includes a directional coupler, power combiner/divider, and a magnitude and phase adjustor to isolate and modify interference signals, ensuring they cancel each other out, thereby improving the Signal to Interference Ratio (SIR) and enhancing calibration accuracy without increasing spurious emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If internal AC technique is used with internal coupler unit deployed inside radio unit, then AC function is fulfilled without auxiliary hardware outside radio unit, but external interferences from Antenna Reference Point adversely affect AC accuracy
Solution Approach 1:
The patent applies the principle of converting harm into benefit by using the external interference signals from the Antenna Reference Point as cancellation targets. The measurement receiver captures these interference signals, and the system generates anti-phase signals to cancel them out, thereby converting the harmful interference into a useful calibration mechanism that improves AC accuracy while maintaining internal AC architecture
Solution Approach 2:
The patent introduces an intermediary mechanism - the measurement receiver and signal processing system - that mediates between the external interference sources and the calibration process. This intermediary captures, processes, and cancels interference signals, allowing the internal AC system to achieve high accuracy without requiring external auxiliary hardware
2Measurement precision
If calibration signal power level is increased to improve SINR, then AC accuracy improves, but spurious emission at ARP increases beyond specified limits
Solution Approach 1:
The patent converts the harmful spurious emissions into a beneficial calibration mechanism by capturing them at the measurement receiver and using them to generate cancellation signals. This allows the system to effectively increase the calibration signal power level for improved SINR and AC accuracy, while the spurious emissions are simultaneously canceled out and prevented from exceeding regulatory limits at the ARP
Solution Approach 2:
The measurement receiver acts as an intermediary that decouples the calibration signal generation from the spurious emission problem. By capturing and processing signals through this intermediary, the system can optimize calibration signal power levels for improved AC accuracy while the intermediary simultaneously manages and cancels spurious emissions to comply with regulatory limits
3Ease of operation
If serial AC sequence is used for calibration, then calibration can be performed, but interference from other radio branches through mutual antenna leakage degrades AC accuracy
Solution Approach 1:
The patent converts the harmful mutual antenna leakage interference into a beneficial calibration resource by capturing it at the measurement receiver. The system uses these leakage signals to generate cancellation signals that actively neutralize the interference, thereby maintaining ease of serial calibration operation while improving AC accuracy by eliminating the degrading effect of antenna leakage
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 solution effectively cancels interference signals, improving the SIR and thus the accuracy of antenna calibration, even in challenging environments like low power stations, by ensuring that interference does not contribute to measurement receiver noise.
Implementation Method 1
a directional coupler having a first port, a second port, a third port and a fourth port, the first port selectively connected to a radio transmitter or a radio receiver and the second port connected to an antenna
Implementation Method 2
a magnitude and phase adjustor connected between the fourth port of the directional coupler and the third port of the power combiner/divider
Implementation Method 3
modifying a magnitude and a phase of the coupled interference signal to generate a modified interference signal... The modified interference signal and the isolated interference signal cancel each other
Implementation Method 4
a power combiner/divider having a first port, a second port and a third port; the first port of the power combiner/divider selectively connected to a measurement receiver or a measurement transmitter
Data Source
AI summary
An apparatus for facilitating antenna calibration comprising: a directional coupler having first, second, third and fourth ports, the first port selectively connected to a radio transmitter or a radio receiver and the second port connected to an antenna; a power combiner/divider having first, second and third ports; the first port of the power combiner/divider selectively connected to a measurement receiver or a measurement transmitter and the second port of the power combiner/divider connected to the third port of the direction coupler; and a magnitude and phase adjustor connected between the fourth port of the directional coupler and the third port of the power combiner/divider. The magnitude and phase adjustor is configured to be tuned such that any signal input to the second port of the directional coupler results in an output smaller than a predetermined threshold at the first port of the power combiner/divider.