Coherent MIMO Radar DDMA Waveform Processing
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Solution Overview
Problem
Current MIMO radar systems using DDMA waveforms require high precision in determining the relative radial velocity of the radar with respect to the target, especially in millimeter wavebands, which is not compatible with low-cost systems and can be affected by aliasing in the Doppler domain.
Innovation Solution
A method for processing coherent MIMO radar using DDMA waveforms that identifies the transmitter corresponding to each signal band in the Doppler spectrum without requiring precise knowledge of the relative radial velocity, by generating waveforms with specific phase ramps and using a cross-correlation signal to determine transmitter association, allowing for unoccupied portions of the Doppler spectrum and non-uniform spacing between signal bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high precision inertial measurement units are used to determine relative radial velocity, then measurement precision of Doppler frequency is improved, but device complexity and cost increase
Solution Approach 1:
The radar system uses its own transmitted signal structure (DDMA waveforms with specific phase ramps) to enable automatic identification of transmitter-signal band associations. The system self-determines the required velocity precision threshold through signal processing rather than relying on external high-precision inertial measurement units, making the system self-sufficient and reducing external dependency.
Solution Approach 2:
The invention changes the approach from measuring physical velocity parameters with high-precision hardware to using signal processing parameters (phase ramps, frequency shifts) that can be determined through cross-correlation algorithms. This parameter transformation allows the system to achieve accurate transmitter identification without high-precision velocity measurement hardware.
2Productivity
If uniform spacing of signal bands in Doppler spectrum is used, then spectral efficiency is improved, but transmitter identification becomes ambiguous without precise velocity knowledge
Solution Approach 1:
The invention introduces asymmetric phase ramp patterns across transmitters that create distinctive, non-uniform signal band positions in the Doppler spectrum. This asymmetry in the signal structure allows each transmitter to be uniquely identified by its specific phase ramp signature, resolving the ambiguity that would otherwise require precise velocity knowledge.
Solution Approach 2:
The phase ramp acts as an intermediary that carries transmitter identification information through the Doppler processing chain. By embedding unique phase ramp signatures in each transmitter's waveform, the system creates an intermediate representation that preserves transmitter identity information even when uniform spectral spacing is used.
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
Enables accurate identification of transmitter signals without needing high-precision inertial measurement units, improving radar efficiency and compatibility with low-cost systems, especially in millimeter waveband applications.
Implementation Method 1
each of the waveforms is generated by applying a different phase modulation between each transmit channel
Implementation Method 2
the centre frequencies of the signals transmitted by the various transmit antennas are slightly shifted with respect to one another, so that these signals can be separated in the Doppler domain
Data Source
AI summary
A method for processing coherent MIMO radar processing DDMA waveforms includes: generating waveforms on transmitters, the waveforms, modulo the pulse repetition frequency, being identical from one transmitter to the next, to within a phase ramp specific to each transmit path; generating, for at least one receiver, a Range-Doppler representation of echoes of transmitted waveforms, where, for each receiver, echoes of a transmitter occupy at least one frequency cell in the Doppler spectrum, each signal band specific to a transmitter, placement of the signal bands in the Doppler spectrum being determined by phase ramp applied to each transmitter, the waveforms generated to leave a portion of Doppler spectrum between two signal bands unoccupied; identifying the transmitter corresponding to each signal band, due to Range-Doppler representation of echoes of transmitted waveforms. The method is suitable for the millimetre band, automotive or aircraft radar, for detection of target relative to the carrier.