Adaptive I/Q Mismatch Calibration for Wideband Transceivers
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Solution Overview
Problem
Existing I/Q mismatch calibration methods in wireless communication systems are inadequate for wideband transceivers, as they either calibrate either the transmitter or receiver first, leading to quality limitations in the later calibration, and fail to accurately address frequency-dependent mismatches, which can result in signal degradation.
Innovation Solution
The proposed adaptive calibration method identifies a reference signal, generates a loopback signal to distinguish Tx and Rx I/Q mismatches, and determines respective mismatch parameters using a finite impulse response filter estimation method, allowing for simultaneous and independent calibration of both the transmitter and receiver signals, even during real-time data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing calibration methods calibrate transmitter or receiver first, then calibration can be performed sequentially, but the quality of later calibration is limited and signal degradation occurs
Solution Approach 1:
The patent segments the I/Q mismatch calibration into two independent parts: transmitter I/Q mismatch calibration and receiver I/Q mismatch calibration. By introducing an additional signal component in the loopback path, the system can separately identify and calibrate Tx I/Q parameters and Rx I/Q parameters independently, rather than having sequential calibration where the second calibration is limited by the first.
Solution Approach 2:
The patent introduces an additional signal (such as a phase shift or frequency offset) as an intermediary in the loopback path. This intermediary signal enables the receiver to distinguish between transmitter-caused I/Q mismatches and receiver-caused I/Q mismatches, allowing independent calibration of both paths without quality limitations.
2Measurement precision
If traditional calibration methods are used, then calibration can be performed, but frequency-dependent mismatches cannot be accurately addressed leading to signal degradation
Solution Approach 1:
The patent employs dynamic calibration signals that can adapt to frequency-dependent characteristics. The additional signal in the loopback path enables the system to measure and calibrate I/Q mismatches at different frequencies independently, allowing accurate compensation for frequency-dependent mismatches that static calibration methods cannot address.
3Reliability
If dedicated training signals are used for calibration, then accurate calibration can be achieved, but normal data transmission is interrupted
Solution Approach 1:
The patent enables continuous calibration during normal data transmission by using the additional loopback signal to identify I/Q mismatch parameters from ongoing traffic. The calibration process does not require interrupting data transmission or using dedicated training signals, as the unique additional signal allows parameter extraction from the continuous data stream.
Data Source
AI summary
The present disclosure includes systems and techniques relating to calibrating I/Q mismatches in communication systems. In some implementations, a reference signal to be transmitted by a transmitter (Tx) is identified. A loopback signal corresponding to the reference signal is generated by passing the reference signal through the TX and a receiver (Rx). The loopback signal includes an additional signal that distinguishes an in-phase/quadrature (I/Q) mismatch caused by the Tx (Tx I/Q mismatch) from an I/Q mismatch caused by the Rx (RX I/Q mismatch). A set of Tx I/Q mismatch parameters and a set of Rx I/Q mismatch parameters are determined based on the reference signal and the loopback signal, using the additional signal. A Tx signal is calibrated based on the set of Tx I/Q mismatch parameters, while a Rx signal is calibrated based on the set of Rx I/Q mismatch parameters, independently from the calibrating the Tx signal.