Doppler Shift Compensation Using Payload Signal Frequency Components
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Solution Overview
Problem
Existing Doppler shift compensation methods that rely on known signal sequences, such as preambles and postambles, reduce transmission efficiency due to the decrease in payload ratio, necessitating a solution that can compensate for Doppler shift regardless of the presence or absence of these sequences.
Innovation Solution
A Doppler shift compensation device and method that includes a signal acquisition unit, a compensation unit, and a search unit to adjust the Doppler shift based on the change amount, focusing on frequency components with power exceeding a threshold, allowing for effective compensation without relying on known signal sequences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a known signal sequence such as a preamble and a postamble is added to a frame for Doppler shift compensation, then Doppler shift can be compensated, but the payload ratio decreases and transmission efficiency deteriorates
Solution Approach 1:
The invention extracts only the necessary portion of the signal (frequency components above threshold) for Doppler shift estimation and compensation, rather than requiring separate known signal sequences. This allows compensation while preserving payload integrity.
Solution Approach 2:
The invention makes the received signal itself serve multiple functions: both as the payload carrier and as the source for Doppler shift estimation. The received signal is used directly for frequency offset calculation without requiring dedicated known sequences.
2Measurement precision
If a known signal sequence is added to estimate Doppler shift, then frequency offset can be corrected, but the frame structure becomes more complex and payload capacity is reduced
Solution Approach 1:
The invention extracts frequency components above a threshold from the received signal to estimate Doppler shift, eliminating the need for separate known signal sequences and simplifying the frame structure while maintaining estimation capability.
3Measurement precision
If Doppler shift compensation is performed using traditional methods with preambles and postambles, then frequency offset can be measured, but the ratio of useful payload decreases
Solution Approach 1:
The received signal serves dual purposes: as the payload to be transmitted and as the reference signal for frequency offset measurement. This eliminates the need for separate known sequences and maximizes payload ratio.
Solution Approach 2:
Only the frequency components above a threshold are extracted for Doppler shift estimation, allowing the method to work with the payload signal itself without requiring additional known sequences.
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 enables efficient Doppler shift compensation in reception signals, maintaining transmission efficiency by compensating for Doppler shift irrespective of the presence of known signal sequences, thereby improving communication quality in satellite IoT systems.
Implementation Method 1
a compensation unit that compensates for a Doppler shift of the reception signal on the basis of a possibility of a change amount of the Doppler shift
Data Source
AI summary
A signal acquisition unit acquires a reception signal received by a reception device from a transmission device that moves relative to the reception device. A compensation unit compensates for a Doppler shift of the reception signal on the basis of a possibility of a change amount of the Doppler shift. A search unit changes a value of a possibility of the change amount of the Doppler shift in a case where a bandwidth having a power equal to or greater than a predetermined threshold in frequency components of the reception signal after the compensation is larger than a predetermined value.