OFDM Frequency Offset Correction Using Pilot Power
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Solution Overview
Problem
The efficiency of frequency offset correction in OFDM systems is low, particularly because existing methods only address frequency offsets caused by laser center frequency offsets and not those caused by filter center frequency offsets.
Innovation Solution
A receiving device and transmitter system that detect and correct frequency offsets by determining the difference between the center frequencies of a laser and a filter using power parameters of a pilot signal, allowing for adjustments to the laser center frequency based on calculated frequency offset values to improve correction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wavelength locker is used to detect the OFDM signal and determine laser center frequency offset, then frequency offset correction can be implemented, but the correction efficiency remains low because it only addresses laser center frequency offset and not filter center frequency offset
Solution Approach 1:
The patent extends the frequency offset correction mechanism to handle both laser center frequency offset and filter center frequency offset using a unified approach. The receiving device calculates frequency offset values that represent the combined effect of both offsets, and the transmitter adjusts the laser center frequency to compensate for both types of offsets simultaneously, making the system universally applicable to multiple offset sources.
Solution Approach 2:
The patent changes the parameter being measured and corrected from only laser center frequency offset to the combined frequency offset caused by both laser and filter center frequency offsets. By using power parameters of pilot signals at different frequencies to calculate a comprehensive frequency offset value, the system adapts to varying offset conditions and improves correction efficiency.
2Ease of manufacture
If only laser center frequency offset is corrected using perturbation signals and wavelength lockers, then the correction process can be implemented, but frequency offsets caused by filter center frequency offset are not addressed
Solution Approach 1:
The patent creates a universal correction mechanism that handles both laser center frequency offset and filter center frequency offset. The receiving device calculates a frequency offset value based on power parameters of pilot signals, and the transmitter uses this value to adjust the laser center frequency, making the same correction mechanism applicable to both types of offsets without requiring separate correction paths.
Solution Approach 2:
The system uses the existing pilot signals in the OFDM transmission to perform frequency offset detection and correction. The power parameters of these pilot signals serve dual purposes: maintaining signal integrity and providing the basis for calculating frequency offset values. This self-service approach eliminates the need for separate detection signals while maintaining correction capability.
Data Source
AI summary
According to a transmitter, a receiving device, and a frequency offset correction method that are provided in embodiments of the present invention, after a power parameter of a pilot in an OFDM signal received by a receiving device is detected, a frequency offset value used to indicate a degree and a direction that are of a difference that is between a center frequency of a filter and a center frequency of a laser and that deviates from a first threshold is determined according to the power parameter of the pilot, and then the receiving device corrects the difference between the center frequency of the laser and the center frequency of the filter according to the determined frequency offset value, thereby implementing frequency offset correction of an OFDM system.