Spread MIMO Radar Synchronization via Reference Signal
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Solution Overview
Problem
Existing automotive MIMO radar systems require precise synchronization of antennas on the scale of a radar carrier frequency, which is challenging with multiple antennas spread over a vehicle, especially when the distance between antennas is large compared to the radar carrier wavelength, limiting their ability to detect targets and measure relative velocity and angle of arrival effectively.
Innovation Solution
An automotive spread MIMO radar system that uses mutually orthogonal radar wave signals and a reference signal transmitted between transceiver antenna units with a known distance, allowing for range-based synchronization without the need for phase-based synchronization on the radar carrier frequency scale, enabling robust time synchronization and correction of Doppler shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple antennas are spread over a vehicle with large distances between them, then the field of view and detection coverage are improved, but precise synchronization on the radar carrier frequency scale becomes difficult to achieve
Solution Approach 1:
A reference signal is introduced as an intermediary between the radar carrier signals and the synchronization process. The reference signal, transmitted at a lower frequency with longer wavelength, serves as a mediator that can traverse large distances between antennas while maintaining synchronizability. By using this intermediate reference signal instead of directly synchronizing high-frequency radar carrier waves over large distances, the system achieves both wide coverage and precise synchronization.
2Area of stationary object
If antennas are spaced by multiple wavelengths, then coverage area is increased, but ambiguity in angular reconstruction occurs
Solution Approach 1:
The reference signal acts as an intermediary that carries positional information between antennas spaced by multiple wavelengths. By transmitting and receiving this reference signal, the system can determine the relative positions and timing of antennas without the ambiguity that would normally arise from large spacing. The reference signal provides the missing information needed for accurate angular reconstruction despite the large inter-antenna distances.
3Device complexity
If standard CAN-bus is used for antenna synchronization, then system complexity is reduced, but synchronization latency exceeds the radar carrier frequency period
Solution Approach 1:
The reference signal serves as an intermediary that enables direct hardware-level synchronization between antennas, bypassing the need for complex software-based CAN-bus communication. By using the reference signal to carry timing information directly between antenna units, the system achieves synchronization with latency well below the radar carrier frequency period, while keeping the overall system complexity manageable through a dedicated reference signal distribution network.
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 unambiguous detection of targets, measurement of range and relative radial velocity, and angle of arrival without the need for precise antenna synchronization on the radar carrier frequency scale, improving the system's robustness and accuracy while maintaining a wide field of view.
Implementation Method 1
automotive spread multiple-input multiple-output configured radar system for detection of targets
Implementation Method 2
measuring an angle of arrival of a radar signal reflected by a target
Implementation Method 3
measuring an angle of arrival of a radar signal reflected by a target... unambiguously measure the relative radial velocity
Data Source
AI summary
An automotive spread MIMO-configured radar system has a plurality of transceiver antenna units for transmitting mutually orthogonal radar waves. Each transceiver antenna unit has a plurality of range gates to indicate a range detected by the transceiver antenna unit. At least one specific transceiver antenna unit (TRx1) is configured to transmit a reference signal received directly by at least one transceiver antenna unit (TRx2) that is separated by an a priori known distance from the specific transceiver antenna unit (TRx1). An evaluation and control unit is configured for reading out the plurality of range gates for the transceiver antenna unit (TRx2), and, based on the read-out range gate that indicates the received reference signal and based on the a priori known distance, for synchronizing the specific transceiver antenna unit (TRx1) and the transceiver antenna unit (TRx2) that received the reference signal and/or for correcting a measured Doppler shift.