DFTS-OFDM Modulation Symbols for Short Radar Pulses
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Solution Overview
Problem
Existing monostatic radar systems face a significant challenge with minimum sensing distances due to the overlap of transmitted and reflected pulses at high frequencies, limiting their application in scenarios like vehicular-based radar for detecting close objects.
Innovation Solution
The implementation of a method using DFTS-OFDM to determine modulation symbols, where only a subset of symbols are set to non-zero values, allowing for a pulse duration shorter than the OFDM symbol duration, thereby reducing interference and enabling sensing of objects at closer distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a radar pulse is transmitted at high frequencies, then the radar can detect objects with higher precision, but the transmitted pulse overlaps with the reflected pulse, causing interference and increasing the minimum sensing distance
Solution Approach 1:
The patent segments the OFDM symbol duration by setting only a subset of modulation symbols to non-zero values while setting other symbols to zero. This segmentation creates a transmitted pulse that is shorter than the full OFDM symbol duration, allowing the pulse to end before the reflected pulse returns, thereby eliminating interference while maintaining high-frequency operation for precise detection
2Length of moving object
If the radar pulse width is reduced to decrease minimum sensing distance, then closer objects can be detected, but the signal energy is reduced
Solution Approach 1:
The patent changes the parameter configuration of modulation symbols by selectively setting specific symbols to non-zero values and others to zero. This parameter change creates a shorter effective pulse duration while concentrating the signal energy into the non-zero symbols, thus reducing minimum sensing distance without proportionally reducing signal energy
Data Source
AI summary
A method, performed by a network node. The method is for determining modulation symbols. The network node includes a modulator based on Discrete-time Fourier Transform Spread (DFTS)-Orthogonal Frequency-Division Multiplexing (OFDM). The network node determines modulation symbols to be input into the modulator. Of a first set of the modulation symbols corresponding to a duration of a DFTS-OFDM symbol, only a first subset of modulation symbols are set to first values of magnitude exceeding zero by a first threshold. The modulation symbols in the first subset are determined to have a first contiguity arrangement. The network node then initiates providing the determined modulation symbols to the modulator.