Co-prime Coded DDM MIMO Radar Velocity Ambiguity Resolution
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Solution Overview
Problem
Existing MIMO automotive radar systems face challenges in accurately detecting the position and movement of objects due to velocity ambiguity caused by overlapped Doppler spectrums from multiple transmitters, particularly in dynamic drive scenes, limiting the number of transmitters that can be used and resulting in poor angular resolution and high false detection rates.
Innovation Solution
A co-prime coded (CPC) Doppler Division Multiplexing (DDM) MIMO radar system is implemented, using co-prime based zero-radial velocity frequency spacing and progressive phase coding to disambiguate overlapped Doppler spectrums, allowing for the construction of a larger virtual array and improved angular resolution by associating Doppler peaks with their corresponding transmitters through CPC decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple transmitters are used in DDM MIMO radar system, then angular resolution is improved, but velocity ambiguity occurs due to overlapped Doppler spectrums
Solution Approach 1:
The Doppler spectrum is segmented into distinct regions for different transmitters using co-prime coded frequency offsets. Each transmitter's Doppler spectrum is separated into its own frequency region, preventing overlap and enabling unambiguous velocity detection while maintaining the benefits of multiple transmitters for angular resolution
Solution Approach 2:
Frequency offsets are applied to the transmitted waveforms from different transmitters according to co-prime coding sequences. This parameter change in the frequency domain creates separated Doppler spectra for each transmitter, resolving the velocity ambiguity problem while allowing multiple transmitters to operate simultaneously
2Length of stationary object
If the number of transmitters is increased, then virtual array aperture is enlarged, but Doppler spectrum overlap worsens velocity ambiguity
Solution Approach 1:
The problem is moved from the time domain to the frequency domain by applying co-prime coded frequency offsets. This dimensional change allows multiple transmitters to operate simultaneously without Doppler spectrum overlap, enabling larger virtual arrays without velocity ambiguity
3Reliability
If co-prime coded frequency offsets are applied, then Doppler spectrum separation is achieved, but system complexity increases
Solution Approach 1:
Complex hardware modifications are replaced with software-based signal processing. The co-prime coded frequency offsets are applied through digital signal processing and correlation algorithms, achieving Doppler spectrum separation without additional physical components or complex hardware changes
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 CPC DDM MIMO radar system achieves better sensitivity, finer angular resolution, and a lower false detection rate by effectively separating Doppler spectrum signals from multiple transmitters, enabling the use of more transmitters within the limited Doppler spectrum and improving target detection accuracy in dynamic environments.
Implementation Method 1
Radar systems may be used to detect the range, velocity, and angle of nearby targets
Implementation Method 2
Jansen FG: 'Automotive Radar Doppler division MIMO with velocity ambiguity resolution capabilities$', 2019 16th European radar conference (EURAD) full, EUMA, 3 October 2019, PP 245 - 248 discloses a Doppler division based MIMO technique, in which transmitted signals are orthogonal iced with frequency offsets on the Doppler dimension
Data Source
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AI summary
A co-prime coded DDM MIMO radar system, apparatus, architecture, and method are provided with a reference signal generator (112) that produces a transmit reference signal; a plurality of DDM transmit modules (11) that produce, condition, and transmit a plurality of transmit signals over which each have a different co-prime encoded progressive phase offset from the transmit reference signal; a receiver module (12) that receives a target return signal reflected from the plurality of transmit signals by a target and generates a digital signal from the target return signal; and a radar control processing unit (20) configured to detect Doppler spectrum peaks in the digital signal, where the radar control processing unit comprises a Doppler disambiguation module (25) that is configured with a CPC decoder to associate each detected Doppler spectrum peak with a corresponding DDM transmit module, thereby generating a plurality of transmitter-associated Doppler spectrum peak detections.