Frequency Offset Modulation MIMO Automotive Radar
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Solution Overview
Problem
Existing radar systems face challenges in distinguishing between Linear Frequency Modulation (LFM) waveforms transmitted by different antennas in MIMO systems, leading to limitations in the number of transmitters that can be used and the resulting angular resolution.
Innovation Solution
The implementation of a frequency offset modulation range and time division MIMO radar system, which combines LFM time-division MIMO with frequency offset modulation range division MIMO to construct very large MIMO arrays. This is achieved by mixing LFM waveforms with different frequency offset signals at each transmit channel, allowing for the separation of transmitters' signals in the range spectrum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If time-division multiplexing is used to separate LFM waveforms from different transmitters, then signal separation is achieved, but the transmission time increases and the number of usable transmitters is limited
Solution Approach 1:
The patent applies frequency offset modulation to shift the carrier frequency of LFM waveforms transmitted by different antennas by distinct amounts. This parameter change in the frequency domain allows simultaneous transmission from multiple antennas without waveform confusion, eliminating the time-division constraint while maintaining signal separability through frequency-domain processing at the receiver
Solution Approach 2:
The patent transitions from time-domain separation (TD-MIMO) to frequency-domain separation by introducing frequency offsets as an additional dimension for distinguishing transmit antennas. This dimensional shift from time to frequency allows multiple transmitters to operate simultaneously without interfering with each other, constructing larger MIMO virtual arrays
2Measurement precision
If the number of transmitters is increased to construct larger MIMO virtual arrays, then angular resolution is improved, but the ability to distinguish LFM waveforms deteriorates
Solution Approach 1:
The patent introduces frequency offset as a distinguishing parameter for each transmitter's LFM waveform. By modulating each transmit antenna's signal with a unique frequency offset, the receiver can identify and separate waveforms from different antennas even when transmitted simultaneously, enabling the use of many more transmitters to construct large MIMO virtual arrays
Solution Approach 2:
The patent uses frequency offset modulation as an intermediary mechanism that enables waveform distinction without requiring time separation. The frequency offset acts as a mediator that carries transmitter identification information, allowing the receiver to disentangle signals from multiple transmitters through frequency-domain analysis
3Quantity of substance
If frame or chirp sequence duration is extended to accommodate more transmitters, then more transmitters can be used, but the maximum Doppler shift measurement capability decreases
Solution Approach 1:
The patent enables continuous simultaneous transmission from all transmit antennas using frequency offset modulation, eliminating the need for sequential time-division transmission. This continuous operation maintains short frame durations while accommodating any number of transmitters, preserving both the ability to use many transmitters and the capability to measure maximum Doppler shifts accurately
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
The solution enables the formation of much larger MIMO virtual arrays compared to conventional TD-MIMO systems, improving angular resolution, sensitivity, and reducing false detection rates while allowing for a larger number of transmitters.
Implementation Method 1
mixing the LFM waveform with a frequency offset signal to generate a frequency-offset modulated LFM waveform
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A radar system, apparatus, architecture, and method are provided for generating a transmit reference or chirp signal that is applied to a waveform generator having a frequency offset generator and a plurality of single channel modulation mixers configured to generate a plurality of transmit signals having different frequency offsets from the transmit reference signal for encoding and transmission as N radio frequency encoded transmit signals which are reflected from a target and received at a receive antenna as a target return signal that is down-converted to an intermediate frequency signal and converted by a highspeed analog-to-digital converter to a digital signal that is processed by a radar control processing unit which performs fast time processing steps to generate a range spectrum comprising N segments which correspond, respectively, to the N radio frequency encoded transmit signals transmitted over the N transmit antennas.