Wireless Frequency Control Using Coarse and Fine Phase Error Detection
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Solution Overview
Problem
Existing frequency control systems in communication systems face difficulties in fast and accurate frequency control, especially with large frequency errors and phase deviations, due to slow detection of phase errors and inability to cope with large phase rotations.
Innovation Solution
A frequency control apparatus that includes an oversampling/phase-rotational-amount detecting section, a coarse-phase-error detector, and a frequency control amount acquisition section, which detects and controls large phase rotations using coarse phase errors, and a minute-phase-error detector for precise control when phase rotations are within specified limits, enabling fast frequency control even with large phase deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase error detection is performed by oversampling symbols at a rate higher than symbol rate, then frequency control precision is improved, but detection time increases making fast control difficult
Solution Approach 1:
The patent divides phase error detection into two segments: coarse phase error detection that quickly identifies large phase deviations, and fine phase error detection that precisely measures small phase deviations. This segmentation allows the system to achieve both fast response for large errors and high precision for small errors, resolving the contradiction between detection speed and precision.
Solution Approach 2:
The patent dynamically switches between different detection methods based on the magnitude of phase deviation. When large phase errors are detected, the system uses coarse detection methods for fast correction; when phase errors are small, it transitions to fine detection methods for precise control. This dynamic adaptation optimizes both detection speed and precision across different operating conditions.
2Measurement precision
If the system waits for average convergence to ±0° phase difference, then detection accuracy is improved, but control speed decreases making fast control difficult
Solution Approach 1:
The patent performs preliminary coarse phase error detection to quickly identify and correct large phase deviations before initiating fine phase error detection. This preliminary action prevents the system from waiting for slow average convergence, enabling fast initial correction followed by precise refinement, thus improving both control speed and accuracy.
Solution Approach 2:
The patent skips the slow average convergence process for large phase errors by directly detecting and correcting coarse phase deviations. This rushing through of the initial large error correction phase allows the system to reach the precision range much faster, improving control speed without sacrificing final detection accuracy.
3Reliability
If the system detects phase rotation by averaging intersymbol phase differences, then detection reliability is improved, but response time increases making fast control difficult
Solution Approach 1:
The patent segments the detection process into reliable coarse detection for large phase errors and precise fine detection for small phase errors. The coarse detection provides reliable quick response for large deviations, while fine detection provides reliable precise control for small deviations, maintaining high reliability across different time scales.
Solution Approach 2:
The patent applies partial averaging for coarse phase error detection to achieve sufficient reliability without the full time cost of complete average convergence. This partial action provides reliable detection for large errors quickly, and then full averaging is applied only for fine detection when precision is needed, optimizing the reliability-time tradeoff.
Data Source
AI summary
A wireless communication apparatus performs fast control even on a large phase rotation of a received signal to synchronize the frequency of a received signal with a specified frequency. A symbol-phase-difference detector detects an intersymbol phase difference of an input signal demodulated by a quadrature demodulator. When a minute-phase-error detector detects an intersymbol minute phase error between symbols whose phase difference has been detected by the symbol-phase-error detector, an oversampling/phase-rotational-amount detecting section detects an intersymbol phase rotational amount of the received signal by oversampling the received signal at a rate higher than a symbol rate. A coarse-phase-error detector detects a coarse phase error between symbols whose phase difference has been detected by the oversampling/phase-rotational-amount detecting section. A frequency control amount calculator computes a frequency control amount for the process station to control the frequency of the input signal.