MIMO Radar Antenna Spacing for Unambiguous Angle Measurement
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Solution Overview
Problem
MIMO radar systems face challenges in accurately determining relative velocities and location angles with high resolution and uniqueness, particularly due to ambiguity in Doppler and angle measurements caused by undersampling below the Nyquist limit.
Innovation Solution
A MIMO radar system design with a transmitter array and receiver array, where antenna distances are optimized to be above the Nyquist limit for unambiguous angle measurements, using a periodic multiplex scheme for unambiguous Doppler measurements, and employing code or time multiplex methods to separate signals from multiple antennas, with phase corrections to resolve ambiguities and achieve high-resolution, unambiguous results.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If antenna distances are increased above the Nyquist limit to achieve unambiguous angle measurements, then angle measurement uniqueness is improved, but measurement precision deteriorates due to undersampling
Solution Approach 1:
The patent transitions from single-array angle measurement to two-array configuration (transmitter array and receiver array), adding a spatial dimension to the measurement system. This enables unambiguous angle determination by combining measurements from both arrays, where the receiver array provides uniqueness and the transmitter array maintains resolution.
Solution Approach 2:
The measurement function is segmented between two separate arrays: the transmitter array handles high-resolution angle estimation, while the receiver array handles unambiguous measurement. This division allows each array to be optimized for its specific function rather than requiring a single array to satisfy both conflicting requirements.
2Device complexity
If the number of transceiver antennas is reduced to save resources, then device complexity is improved, but measurement precision deteriorates
Solution Approach 1:
Each antenna element in the MIMO system performs multiple functions: transmitting signals, receiving reflected signals, and participating in both velocity and angle measurements. The systematic use of multiple antennas with orthogonal codes allows the system to achieve high measurement precision without requiring an excessive number of antenna elements.
Solution Approach 2:
The patent employs periodic multiplex schemes with orthogonal codes transmitted in sequence through different antennas. This periodic transmission pattern allows the system to extract multiple measurement dimensions (velocity, angle, range) from a limited set of antenna elements by analyzing the temporal and spatial patterns of the received signals.
3Reliability
If periodic multiplex schemes are used to achieve unambiguous Doppler measurements, then reliability of velocity measurement is improved, but productivity deteriorates due to extended measurement time
Solution Approach 1:
The MIMO radar system continuously transmits orthogonal codes through multiple antennas in parallel, maintaining continuous useful measurement action. Unlike sequential methods that wait for each code to complete, the system processes multiple codes simultaneously through the multi-antenna array, eliminating idle time and maintaining continuous measurement productivity.
Solution Approach 2:
The system transmits more orthogonal codes than the minimum required for unambiguous velocity measurement. This excessive action provides redundant measurement data that can be processed in parallel, reducing the effective measurement time while maintaining reliability through the redundancy of multiple orthogonal code measurements.
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 efficient and resource-preserving signal evaluation by resolving ambiguities in Doppler and angle measurements, achieving high-resolution and unambiguous results with a small number of transceiver antennas, and combining results for shared data compression in relative velocity and angle dimensions.
Implementation Method 1
Radar systems are used to an increasing extent in motor vehicles for detecting the vehicle surroundings
Implementation Method 2
the phase offset caused by the Doppler effect is appropriately corrected
Data Source
AI summary
A MIMO radar system including a transmitter array, and a receiver array, the antenna distances in one of the transmitter and receiver arrays being above the Nyquist limit for unambiguous angle measurements, but the antenna distances in the combination of the transmitter and receiver arrays being below this Nyquist limit. The system also includes a control and evaluation unit.