Adaptive Frequency Shift Correction for Wi-Fi Receiver DC Offset
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Solution Overview
Problem
Wireless communication systems, particularly Wi-Fi networks, face performance degradation due to residual DC components and frequency offsets, which lead to interference and reduced dynamic range, especially in systems using high modulation coding schemes and Orthogonal Frequency Division Modulation (OFDM).
Innovation Solution
The implementation of adaptive frequency shift correction through Phase Lock Loop (PLL) frequency compensation, where the PLL is reconfigured based on estimated frequency offsets to maintain the residual DC component at zero frequency, allowing for effective removal by High Pass Filters and minimizing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional radio front-end calibration is used to reduce DC offset, then the DC offset is reduced, but residual DC component remains that cannot be completely removed
Solution Approach 1:
The patent implements a feedback mechanism where the receiver continuously monitors the DC offset level in received signals and dynamically adjusts the front-end calibration parameters. This closed-loop approach allows the system to detect residual DC components and apply corrective adjustments in real-time, preventing the residual DC component from causing performance degradation.
Solution Approach 2:
The patent changes the calibration parameters of the radio front-end based on detected DC offset conditions. By dynamically adjusting parameters such as mixer local oscillator levels and amplifier gain settings, the system adapts to varying DC offset conditions and achieves more complete DC offset removal compared to fixed conventional calibration.
2Object-affected harmful factors
If High Pass Filter is employed to remove residual DC component, then residual DC component is filtered, but frequency offset causes the DC component to shift away from zero frequency reducing filter effectiveness
Solution Approach 1:
The patent applies frequency offset correction before the High Pass Filter stage by adjusting the local oscillator frequency to compensate for detected frequency offsets. This preliminary frequency alignment ensures that the residual DC component remains at zero frequency, making the subsequent High Pass Filter operation effective at removing the DC component without losing signal content.
Solution Approach 2:
The system implements frequency offset detection and correction feedback that continuously monitors frequency drift and adjusts the local oscillator accordingly. This feedback loop maintains the DC component at zero frequency despite frequency offsets, ensuring optimal High Pass Filter performance.
3Productivity
If frequency offset is not corrected, then system operation is maintained, but signal quality degrades especially in high modulation coding schemes
Solution Approach 1:
The patent implements dynamic frequency offset correction that continuously adapts to changing frequency conditions. The system dynamically adjusts the local oscillator frequency based on real-time detection of frequency offsets, maintaining optimal signal quality across varying operating conditions and modulation schemes without interrupting system operation.
Solution Approach 2:
The system employs feedback-based frequency offset detection and correction that monitors signal quality metrics and adjusts frequency compensation accordingly. This feedback mechanism ensures that signal quality is maintained in high modulation coding schemes by continuously correcting frequency drift while keeping the system operational.
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 approach significantly improves signal quality by promptly correcting frequency offsets for each received frame, reducing interference and maximizing the dynamic range of the receiver, thus enhancing the performance of Wi-Fi systems, especially in high modulation coding schemes and OFDM systems.
Implementation Method 1
performing packet detection to detect at least a portion of a preamble part of the current frame according to a default frequency output from a PLL, estimating a frequency offset between the default frequency and a frequency used to carry information in the preamble part of the current frame, reconfiguring the PLL according to the frequency offset to output a compensated frequency
Data Source
AI summary
Methods and wireless communication devices for processing wireless signals with adaptive frequency shift correction. An embodiment of the method includes receiving a wireless signal by the receiver, performing packet detection to detect at least a portion of a preamble part of a current frame carried in the wireless signal according to a default frequency output from a Phase Lock Loop (PLL), estimating a frequency offset between the default frequency and a frequency used to carry information in the preamble part of the current frame, reconfiguring the PLL according to the frequency offset to output a compensated frequency, and processing a packet part of the current frame using the compensated frequency output from the PLL. The method may further mitigate the impact of a residual Direct current (DC) component by filtering the wireless signal based on the compensated frequency.