Millimeter-Wave I/Q Calibration Using Dual Loopback Paths
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Solution Overview
Problem
5G communication systems face challenges in calibrating frequency-dependent I/Q imbalance, which leads to mirror-frequency interference and degradation in system performance, especially in ultra-wideband systems using millimeter waves, as existing calibration techniques are inadequate for joint transmitter and receiver calibration and often require separate estimation of frequency-independent phase imbalances.
Innovation Solution
A method utilizing a loopback hardware structure with specifically designed training signals to determine frequency domain compensation filters and finite impulse response (FIR) filters, allowing for joint calibration of transmitter and receiver I/Q imbalance, effectively removing image components and suppressing noise across a wide bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing calibration techniques are used for I/Q imbalance, then calibration can be performed, but frequency-dependent I/Q imbalance cannot be properly calibrated and mirror-frequency interference occurs
Solution Approach 1:
The patent segments the calibration process into two distinct loopback routes: a first loopback route for frequency-independent phase imbalance estimation and a second loopback route for frequency-dependent I/Q imbalance calibration. This segmentation allows each route to be optimized for its specific calibration task, resolving the contradiction by enabling proper handling of both types of imbalance separately.
Solution Approach 2:
The patent introduces specifically designed training signals as intermediaries to facilitate the calibration process. These training signals are transmitted through the loopback routes and used to estimate the imbalance characteristics. The training signals act as mediators that enable the system to measure and compensate for both frequency-independent and frequency-dependent imbalances, thereby eliminating mirror-frequency interference.
2Measurement precision
If separate estimation of frequency-independent phase imbalances is performed, then phase calibration can be achieved, but joint transmitter and receiver calibration is incomplete
Solution Approach 1:
The patent merges the frequency-independent phase imbalance estimation and frequency-dependent I/Q imbalance calibration into a unified joint calibration framework. By combining these processes and using the loopback hardware structure with specially designed training signals, the system achieves complete joint transmitter and receiver calibration without requiring separate complex procedures, thus reducing overall calibration complexity while improving completeness.
Solution Approach 2:
The patent implements a feedback mechanism where the estimated imbalance parameters from the training signal transmission are used to adjust and compensate the transmitter and receiver settings. The loopback structure provides feedback paths that allow the system to measure the actual imbalance and apply corrections, enabling precise joint calibration of both transmitter and receiver components.
3Ease of manufacture
If conventional calibration methods are used, then simple implementation is possible, but image components cannot be effectively removed across wide bandwidth
Solution Approach 1:
The patent changes the parameters of the training signals to specifically target frequency-dependent I/Q imbalance characteristics. By designing training signals with appropriate frequency content and using them through the loopback routes, the system can estimate and compensate for image components across the entire wide bandwidth. This parameter change approach maintains implementation simplicity while dramatically improving image rejection performance.
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AI summary
The disclosure relates to a communication method and system for converging a 5th-Generation (5G) communication system for supporting higher data rates beyond a 4th-Generation (4G) system with a technology for Internet of Things (IoT). A method of operating an electronic device in a wireless communication system is provided. The method includes inputting training signals into a first loopback route and a second loopback route, determining a loopback gain and a loopback phase, based on a first training signal passing through the first loopback route and a second training signal passing through the second loopback route, determining a frequency domain compensation filter, based on the loopback gain and the loopback phase, determining an FIR filter and a DC offset, based on the frequency domain compensation filter, and compensating for a transmission signal and a reception signal, based on the FIR filter and the DC offset.