PMCW MIMO Radar Transmitter Coding for Doppler Speed
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Solution Overview
Problem
Conventional PMCW CD MIMO radar systems face limitations in Doppler bin construction and phase-mismatch issues due to the code length requirement for transmitter coding, leading to reduced maximum unambiguous Doppler speed and poor transmitter separation performance.
Innovation Solution
Implementing an optimized transmitter coding process with orthogonal outer codes of length equal to the number of Doppler bins, and using joint transmitter decoding and Doppler filtering with complex conjugate weighting to eliminate the need for dedicated decoders and account for phase rotation effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional transmitter coding with code length requirement is used, then transmitter separation is achieved, but maximum unambiguous Doppler speed is reduced
Solution Approach 1:
The patent combines transmitter decoding and Doppler filtering into a single joint processing operation. By merging these two functions that were previously separate into one unified process, the system eliminates the need for dedicated decoders and achieves both transmitter separation and Doppler measurement simultaneously, thereby extending the maximum unambiguous Doppler speed while maintaining separation performance.
Solution Approach 2:
The joint decoder-Doppler filter structure serves multiple functions: it performs transmitter signal separation, Doppler frequency estimation, and phase-mismatch compensation all within a single processing block. This multi-functional approach allows the system to achieve extended Doppler measurement capabilities without sacrificing transmitter separation accuracy.
2Measurement precision
If conventional transmitter coding process is used, then transmitter separation is possible, but phase-mismatch issues occur
Solution Approach 1:
The joint decoding and Doppler filtering process incorporates feedback mechanisms that account for phase rotations caused by Doppler effects. By continuously adjusting the decoding process based on detected phase-mismatch conditions, the system compensates for these errors and maintains reliable transmitter separation even in the presence of Doppler shifts.
3Measurement precision
If dedicated decoders are used for transmitter decoding, then transmitter separation is achieved, but system complexity increases
Solution Approach 1:
The patent merges the dedicated decoder functionality with the Doppler filter into a single joint processing block. This consolidation eliminates the need for separate decoder components while maintaining the ability to separate transmitter signals, thereby reducing overall system complexity without sacrificing separation performance.
Solution Approach 2:
The joint decoder-Doppler filter structure performs multiple functions within a single component: transmitter signal separation, Doppler frequency estimation, and phase-error compensation. This multi-functional design replaces what would traditionally require multiple separate components, simplifying the overall system architecture.
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
This approach extends the maximum unambiguous Doppler shift measurable by the system by a factor equal to the number of transmitters, improves transmitter separation, and enhances the performance of the MIMO virtual aperture.
Implementation Method 1
each transmitter channel transmits with a broad radiation pattern to illuminate the entire field of view (FOV) of the radar
Implementation Method 2
the transmitted waveforms are also not identical, but are orthogonal to each other in either time, frequency, code, or other domains. At the receiver, signals originated from individual transmitter channels are then separated
Implementation Method 3
extract targets' range, Doppler speed (i.e., radial velocity), and direction of arrival (DoA) information
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
Embodiments are provided for a radar system including: an N number of transmit antennas; and an N number of phase shift keying (PSK) coders, each assigned a respective optimized transmitter code of a set of optimized transmitter codes, each optimized transmitter code of the set comprises a sequence of K code chips, each optimized transmitter code of the set is orthogonal to every other optimized transmitter code of the set, spectral analysis of a cross-correlation between any two optimized transmitter codes results in sidelobes no greater than a predetermined detection threshold, each PSK coder encodes K ranging waveform blocks according to the sequence of K code chips of the respective optimized transmitter code and produces a respective optimized coded sequence, and each of the N transmit antennas outputs the respective optimized coded sequence at the same time.