Millimeter-Wave DPD Calibration Using Near-Field Path Search
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Solution Overview
Problem
Calibration of millimeter wave communication systems is challenging due to the high cost and complexity of independent test equipment, measurement uncertainty, and the lack of test access to antenna connectors, particularly in systems using feedback receivers (FBRx) for digital predistortion (DPD) calibration.
Innovation Solution
Implementing a training path searching algorithm to select and calibrate transmission and receive elements based on gain settings and near field power measurements, eliminating the need for costly feedback receivers (FBRx) by using a loopback TX signal for path searching and digital predistortion calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If feedback receivers (FBRx) are used for digital predistortion calibration, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the calibration measurement function from the complex FBRx system and implements it using existing antenna elements and signal processing capabilities. By taking out the measurement function and separating it from the expensive feedback receiver hardware, the system achieves calibration precision without the associated complexity and cost.
Solution Approach 2:
The patent creates a virtual copy of the feedback receiver functionality through digital signal processing. Instead of using physical FBRx hardware, the system uses existing transmit and receive elements to simulate the measurement function, achieving the same calibration precision through software-based signal routing and processing.
2Measurement precision
If independent test equipment is used for calibration, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges the calibration measurement function with the existing communication signal paths. By combining the test and measurement functions with the regular transmit and receive elements, the system eliminates the need for separate independent test equipment while maintaining measurement precision through integrated signal processing.
Solution Approach 2:
The patent makes the existing antenna elements and signal paths multi-functional, allowing them to serve both communication and calibration measurement purposes. This universality eliminates the need for dedicated test equipment while maintaining measurement precision through proper signal routing and processing.
3Measurement precision
If FBRx is used for DPD calibration, then calibration accuracy is improved, but space usage increases
Solution Approach 1:
The patent makes existing antenna elements serve dual purposes: regular communication and calibration measurements. By making the antenna array multi-functional, the system achieves calibration accuracy without adding the space required for separate FBRx hardware and associated test equipment.
4Measurement precision
If test access to antenna connectors is provided, then calibration precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts the measurement capability from the physical antenna connector interface and implements it through the existing signal processing chain. By taking out the measurement function from the physical layer and moving it to the signal processing layer, the system achieves calibration precision without requiring additional test access points or connectors.
Data Source
AI summary
Aspects described herein include devices and methods for facilitating digital predistortion calibration. One aspect includes selecting a first transmission element from a plurality of transmission elements associated with a first antenna element of a plurality of antenna elements in an antenna array of the millimeter wave communication device, wherein the first transmission element is selected based on a gain setting for the first transmission element, selecting a reference transmission power for a test transmission from the first transmission element as part of a path searching operation of the millimeter wave communication device, determining a selected receive element of the plurality of receive elements based on a near field power measurement of the reference transmission power from the first transmission element using the selected receive element and a set of selection criteria, and setting a digital predistortion calibration setting using the reference transmission power and the near field power measurement.