Receiver Phase Calibrator Frequency Offset Compensation
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Solution Overview
Problem
Conventional transmitters and receivers in telecommunication systems suffer from frequency offsets that blur the demodulated phase, leading to symbol decision errors, and existing solutions are inadequate for effective compensation.
Innovation Solution
A receiver comprising an I/Q demodulator, filter, angle subtractor, phase calibrator, and symbol decider that generates a calibrated phase signal by filtering noise, estimating phase differences using preamble signals, and compensating payload symbols to mitigate frequency offsets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frequency offset compensation is not implemented, then the receiver structure remains simple, but the demodulated phase becomes blurred and symbol decision errors occur
Solution Approach 1:
The patent applies preliminary action by using preamble signals before the actual data transmission to estimate and compensate for frequency offset. The phase calibrator processes the preamble signals to determine phase rotation caused by frequency offset, then applies this compensation to subsequent payload symbols, preventing phase blurring before it occurs.
Solution Approach 2:
The patent implements feedback by using the estimated phase rotation from preamble signals to adjust and compensate the phase of received symbols. The phase calibrator continuously monitors the phase difference and applies corrective rotation to maintain accurate symbol detection, creating a closed-loop compensation mechanism.
2Measurement precision
If noise signals are not filtered, then the processing speed remains high, but the phase estimation accuracy deteriorates due to noise interference
Solution Approach 1:
The patent applies the taking out principle by extracting and removing noise components from the received signal through filtering. The filter selectively removes frequency components above a predetermined threshold, separating the useful signal from noise interference, thereby improving phase estimation accuracy without significantly impacting processing speed.
3Adaptability or versatility
If crystal deviation tolerance is increased, then the receiver can operate under higher frequency offsets, but the phase calibration becomes more challenging
Solution Approach 1:
The patent applies self-service by enabling the receiver to automatically estimate and compensate for its own frequency offset using the transmitted preamble signals. The phase calibrator independently determines the phase rotation caused by crystal deviation and applies corrective transformation, allowing the system to adapt to various crystal deviations without external calibration assistance.
Data Source
AI summary
A receiver comprises an I/Q demodulator generates an angular signal by demodulating an in-phase branch and a quadrature branch of a received signal; a filter communicatively coupled to the I/Q demodulator and configured to generate a filtered angular signal by filtering out a noise signal having a frequency higher than a predetermined frequency value from the angular signal; an angle subtractor communicatively coupled to the filter and configured to generate a phase signal based on the filtered angular signal; a phase calibrator communicatively coupled to the angle subtractor and configured to generate a calibrated phase signal based on at least one received preamble signal corresponding to the phase signal and a known value of the at least one received preamble signal corresponding to the phase signal; and a symbol decider communicatively coupled to the phase calibrator and configured to generate an output symbol based on the calibrated phase signal.