Direct Conversion Receiver I/Q Imbalance Correction
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Solution Overview
Problem
Multiband radios and personal communication devices face limitations in range and reliability due to RF interference, spectrum spread, and I/Q imbalance, which affect their usability and connectivity, especially in emergency response situations.
Innovation Solution
A wireless communication system that includes a receiver front end for tuning RF signals, an I/Q compensation module using a linear minimum mean-square error (LMMSE) module to correct I/Q imbalance, and a base band receiver for digitizing the output to generate receiver data, thereby improving signal quality and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional RF receiver components are used to amplify and filter signals, then the receiver can operate across multiple frequency bands and standards, but the ability to pull the signal out of noise is limited due to amplified noise and RF interference
Solution Approach 1:
The patent replaces traditional analog RF receiver components (amplifiers, filters) with a direct conversion system that uses digital signal processing. The RF signal is converted directly to baseband using a mixer with local oscillator, and then processed digitally through correlation detection, eliminating the need for traditional analog filtering and amplification that amplify noise.
Solution Approach 2:
The patent changes the operating parameters by using correlation detection instead of traditional envelope detection. The system correlates the received signal with a locally generated reference signal to extract information, which provides superior noise rejection compared to traditional methods while maintaining multi-standard compatibility.
2Adaptability or versatility
If multiband radios support multiple frequency bands and standards, then versatility is improved, but I/Q imbalance and spectrum spread occur limiting usable range
Solution Approach 1:
The patent implements feedback mechanisms through adaptive equalization and channel estimation. The system continuously monitors signal quality and adjusts the equalization coefficients to compensate for I/Q imbalance and channel variations, maintaining reliable communication across multiple frequency bands and standards.
Solution Approach 2:
The patent uses dynamic adaptive equalization that adjusts to changing channel conditions in real-time. The equalization coefficients are updated based on current signal characteristics, allowing the system to maintain optimal performance across different frequency bands and standards despite varying I/Q imbalance and spectrum spread conditions.
3Length of stationary object
If traditional amplification is used to increase signal strength, then transmission range is extended, but noise is also amplified reducing signal-to-interference ratio
Solution Approach 1:
The patent replaces analog amplification with digital signal processing techniques. Instead of amplifying the RF signal through analog stages that amplify noise, the system uses correlation detection and adaptive equalization in the digital domain to extract and enhance the signal, providing noise rejection while extending transmission range.
Solution Approach 2:
The patent introduces an intermediary processing stage using correlation detection. This intermediary process correlates the received signal with a reference signal to extract information, providing noise rejection and signal enhancement without the need for high-gain analog amplification that would amplify noise and degrade the signal-to-interference ratio.
Data Source
AI summary
A method of operation of a wireless communication system includes: tuning a receiver front end for receiving a radio-frequency signal; correcting, with an in-phase/quadrature (I/Q) compensation module, an I/Q imbalance from the receiver front end including estimating by a linear minimum mean-square error (LMMSE) module; and processing by a base band receiver for digitizing an output of the I/Q compensation module for generating a receiver data.