PMCW Radar Velocity Labeled Multiplexing
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Solution Overview
Problem
Conventional MIMO radar systems face challenges with motion-induced phase errors, increased measurement time, velocity ambiguity, and high hardware complexity due to existing multiplexing schemes like TDM, FDM, and CDM, which affect the accuracy and efficiency of range and velocity computation.
Innovation Solution
A phase modulated continuous wave (PMCW) MIMO radar system employs velocity-labeled multiplexing (VLM) by simultaneously transmitting PMCW signals with phase offsets, allowing for efficient computation of range, velocity, and direction of objects using a virtual receiver array and reduced processing resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If Time Division Multiplexing (TDM) is used to provide orthogonal transmit signals, then hardware complexity is reduced, but motion-induced phase error increases and measurement time increases
Solution Approach 1:
The patent changes the multiplexing parameter from time-domain separation (TDM) to frequency-domain separation (FDM) by assigning different frequency offsets to each transmitter. This parameter change resolves the contradiction by maintaining low hardware complexity while eliminating motion-induced phase errors through frequency-based orthogonality instead of time-based orthogonality.
Solution Approach 2:
The patent transitions from time-domain multiplexing to frequency-domain multiplexing, adding a frequency dimension to the signal separation. This dimensional change allows simultaneous transmission from multiple transmitters without the phase errors introduced by time delays, while maintaining computational efficiency through frequency-based processing.
2Measurement precision
If Frequency Division Multiplexing (FDM) is used to provide orthogonal transmit signals, then phase error is reduced, but receiver bandwidth increases and hardware complexity increases
Solution Approach 1:
The patent optimizes the frequency offset parameters to achieve the minimum necessary bandwidth while maintaining orthogonality. By carefully selecting frequency offsets that are sufficiently separated to avoid interference but small enough to fit within a practical bandwidth, the system achieves low phase error without excessive hardware complexity.
3Reliability
If Code Division Multiplexing (CDM) is used to provide orthogonal transmit signals, then orthogonality is achieved through spread coding, but computational intensity increases and velocity spectrum sidelobe levels increase
Solution Approach 1:
The patent changes from code-based multiplexing to frequency-based multiplexing with simple frequency offsets. This parameter change maintains reliable signal orthogonality through frequency separation while dramatically reducing computational requirements, as frequency-based processing is less intensive than the cross-correlation operations required for code-based demultiplexing.
4Productivity
If multiple transmitters operate simultaneously without velocity labeling, then processing resources are reduced, but velocity ambiguity increases
Solution Approach 1:
The patent introduces velocity labels as an intermediary parameter that associates specific frequency offsets with velocity information. This intermediary allows the system to simultaneously transmit from multiple transmitters without velocity ambiguity, as the velocity labels provide the necessary disambiguation information during signal processing while maintaining processing efficiency.
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 PMCW radar system achieves reduced processing requirements, enhanced signal-to-noise ratio, and improved angular resolution by distributing energy in the velocity spectrum based on phase offsets, allowing for accurate target detection and velocity measurement with reduced computational resources.
Implementation Method 1
A phase modulated continuous wave (PMCW) radar system includes a first transmit antenna that transmits a first transmission based on a first modulation signal. The second transmit antenna transmits a second transmission based on a second modulation signal.
Implementation Method 2
A receiving antenna receives an echo signal corresponding to the first transmission or the second transmission.
Data Source
AI summary
A phase modulated continuous wave (PMCW) multiple input multiple output (MIMO) radar system is described herein. The radar system is configured to compute range, velocity, and direction of arrival angle of objects relative to the radar system. The radar system includes several transmitting antennas and several receiving antennas, where selected transmitting antennas simultaneously transmit radar signals based on the same modulation signal. Per transmitting antenna, the transmissions are modulated with respective phase offsets on a per pulse repetition interval (PRI) basis. Hence, a coupling between phase shifts over PRI and transmitter positions is established. Effectively, then, each transmitting antenna is labeled with a velocity offset that corresponds to the phase rate of change assigned to the transmitting antenna. This approach is referred to herein as velocity-labeled multiplexing (VLM).