MIMO radar supporting target reflection signal overlap detection

Abstract

A MIMO radar supporting overlapping detection of reflected signals from objects is disclosed. A system and method for processing reflected received radar signals are presented. A range partition matrix is ​​generated from a range-Doppler antenna cube generated using reflections of multiple transmitted radar signals. A first range partition array comprising multiple values ​​associated with different Doppler partitions is determined, and an offset range partition array comprising the multiple values ​​of the first range partition array offset by a certain number of Doppler partitions is generated. First Doppler partitions in the first range partition array and the offset range partition array, each comprising non-zero values, are determined, and the values ​​associated with the first Doppler partitions in the first range partition array are set to zero to generate a corrected range partition array. The radar system uses the corrected range partition array to determine an estimated direction of arrival.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to Romanian patent application No. A202400763, filed December 2, 2024, pursuant to 35 USC § 119, the contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure generally relates to radar systems and associated operating methods. In one aspect, this disclosure relates to a Doppler division multiplexing (DDM) multiple-input multiple-output (MIMO) radar system configured to mitigate Doppler spectral overlap in signals processed by the radar system. Background Technology

[0004] A radar system transmits electromagnetic signals and receives the reflected signals. The time delay and / or variation of the time delay between the transmitted and received signals can be determined and used to calculate the distance and / or velocity of the object causing the reflection. For example, in automotive applications, automotive radar systems can be used to determine the distance and / or velocity of oncoming vehicles and other obstacles.

[0005] Automotive radar systems enable the implementation of Advanced Driver Assistance Systems (ADAS) functions, potentially leading to increasingly safer driving and ultimately fully autonomous driving platforms. These systems use radar as the primary sensor for ADAS operation.

[0006] In radar systems, signal processing requires analyzing data sets to determine the direction of arrival (DOA) of an object represented in a range-Doppler dataset. If the radar system is configured as a Doppler partition-multiplexed (DDM) multiple-input multiple-output (MIMO) radar system, there is a risk of Doppler spectral signal overlap within the dataset, which can reduce the accuracy of any such DOA estimates, especially when high-velocity or nearby objects are located near the radar system. Summary of the Invention

[0007] In some aspects, the technology described herein relates to a radar system comprising: a plurality of transmitter modules configured to transmit a plurality of transmitted radar signals according to a Doppler domain multiplexing (DDM) scheme; a plurality of receiver modules configured to receive reflections of the plurality of transmitted radar signals reflected by at least one object, and to generate digital signals based on the received reflections; and a signal processor configured to: generate a range-Doppler antenna cube representing the digital signals, the range-Doppler antenna cube comprising at least a plurality of range partitions and a plurality of Doppler partitions; and for each of the plurality of range partitions of the range-Doppler antenna cube: extract range information from the range-Doppler antenna cube. The distance partitioning matrix is ​​used to determine a first distance partitioning array associated with a first receiver module, wherein the first distance partitioning array includes multiple values ​​associated with different Doppler partitions; an offset distance partitioning array is determined to offset a certain number of Doppler partitions determined by the DDM scheme, the offset distance partitioning array including the multiple values ​​of the first distance partitioning array; first Doppler partitions in the first distance partitioning array and the offset distance partitioning array, each including non-zero values; and values ​​associated with the first Doppler partitions in the distance partitioning array are set to zero to generate a corrected distance partitioning array; and the corrected distance partitioning array is used to determine the estimated direction of arrival of the object.

[0008] In some aspects, the technology described herein relates to a radar system in which the first range partition array is a first decoded bitmap, and the offset range partition array is an offset version of the first decoded bitmap, and wherein, in order to determine the first Doppler partition in the first range partition array and the offset range partition array, each comprising a non-zero value, the signal processor is further configured to: add the first range partition array to the offset range partition array to produce a summed range partition array; and determine that a first value in the summed range partition array associated with the first Doppler partition is equal to or greater than two.

[0009] In some respects, the technology described herein relates to a radar system in which the signal processor is configured to: determine two neighboring Doppler partitions in the summed range partition array, each associated with a value equal to or greater than a value in the summed range partition array; and set the value associated with the two neighboring Doppler partitions in the range partition array to zero to generate the corrected range partition array.

[0010] In some aspects, the technology described herein relates to a radar system in which, in order to set the value associated with the first Doppler partition in the range partition array to the zero value to produce a corrected range partition array, the signal processor is further configured to: determine a one-dimensional bitmap, wherein the index of each value in the one-dimensional bitmap corresponds to a Doppler partition of the range partition array; set a first bitmap value in the one-dimensional bitmap to a '0' value, wherein the first bitmap value has an index corresponding to the first Doppler partition; and multiply the one-dimensional bitmap by the range partition array to produce the corrected range partition array.

[0011] In some respects, the technology described herein relates to a radar system in which the first range partition array comprises multiple analog values.

[0012] In some respects, the technology described herein relates to a radar system in which, in order to determine a first Doppler partition in a first range partition array and an offset range partition array, each comprising a non-zero value, the signal processor is further configured to determine that a first non-zero value in the first range partition array at the first Doppler partition is within a threshold of a second non-zero value in the offset range partition array at the first Doppler partition.

[0013] In some respects, the techniques described herein relate to a radar system in which the threshold indicates that the first non-zero value is within a certain order of magnitude of the second non-zero value.

[0014] In some aspects, the technology described herein relates to a radar system comprising: a plurality of receiver modules configured to receive reflections of a plurality of transmitted radar signals; and a signal processor configured to: extract a range partition matrix from a range-Doppler antenna cube generated using the reflections of the plurality of transmitted radar signals; determine a first range partition array, the first range partition array including a plurality of values ​​associated with different Doppler partitions; determine an offset range partition array offset by a number of Doppler partitions, the offset range partition array including the plurality of values ​​of the first range partition array; determine first Doppler partitions in the first range partition array and the offset range partition array, each including non-zero values; set the values ​​associated with the first Doppler partitions in the first range partition array to zero to generate a corrected range partition array; and use the corrected range partition array to determine an estimated direction of arrival of an object.

[0015] In some respects, the technology described herein relates to a radar system in which the plurality of transmitted radar signals are transmitted according to a Doppler domain multiplexing (DDM) scheme, and the number of Doppler partitions is determined by the DDM scheme.

[0016] In some respects, the techniques described herein relate to a radar system in which the first range partition array is a first decoded bitmap and the offset range partition array is an offset version of the first decoded bitmap.

[0017] In some respects, the technology described herein relates to a radar system in which, in order to determine a first Doppler partition in a first range partition array and an offset range partition array, each comprising a non-zero value, the signal processor is further configured to: add the first range partition array to the offset range partition array to produce a summed range partition array; and determine a first value in the summed range partition array associated with the first Doppler partition that is equal to or greater than two.

[0018] In some respects, the technology described herein relates to a radar system in which the signal processor is configured to: determine two neighboring Doppler partitions in the summed range partition array, each associated with a value equal to or greater than a value in the summed range partition array; and set the value associated with the two neighboring Doppler partitions in the range partition array to zero to generate the corrected range partition array.

[0019] In some aspects, the technology described herein relates to a radar system in which, in order to set the value associated with the first Doppler partition in the range partition array to the zero value to produce a corrected range partition array, the signal processor is further configured to: determine a one-dimensional bitmap, wherein the index of each value in the one-dimensional bitmap corresponds to a Doppler partition of the range partition array; set a first bitmap value in the one-dimensional bitmap to a '0' value, wherein the first bitmap value has an index corresponding to the first Doppler partition; and multiply the one-dimensional bitmap by the range partition array to produce the corrected range partition array.

[0020] In some respects, the technology described herein relates to a radar system in which the first range partition array comprises multiple analog values.

[0021] In some respects, the technology described herein relates to a radar system in which, in order to determine a first Doppler partition in a first range partition array and an offset range partition array, each comprising a non-zero value, the signal processor is further configured to determine that a first non-zero value in the first range partition array at the first Doppler partition is within a threshold of a second non-zero value in the offset range partition array at the first Doppler partition.

[0022] In some respects, the techniques described herein relate to a radar system in which the threshold indicates that the first non-zero value is within a certain order of magnitude of the second non-zero value.

[0023] In some aspects, the technology described herein relates to a method comprising: receiving reflections of a plurality of transmitted radar signals using a receiver system; extracting a range partition matrix from a range-Doppler antenna cube generated using the reflections of the plurality of transmitted radar signals; determining a first range partition array, the first range partition array comprising a plurality of values ​​associated with different Doppler partitions; determining an offset range partition array offset by a number of Doppler partitions, the offset range partition array comprising the plurality of values ​​of the first range partition array; determining a first Doppler partition in the first range partition array and the offset range partition array, each comprising a non-zero value; setting the value associated with the first Doppler partition in the first range partition array to zero to generate a corrected range partition array; and using the corrected range partition array to determine an estimated direction of arrival of an object.

[0024] In some respects, the technology described herein relates to a method that further includes transmitting the plurality of transmitted radar signals according to a Doppler domain multiplexing (DDM) scheme, wherein the number of Doppler partitions is determined by the DDM scheme.

[0025] In some aspects, the techniques described herein relate to a method in which the first distance partition array is a first decoded bitmap, and the offset distance partition array is an offset version of the first decoded bitmap, and the method further includes, in order to determine the first Doppler partition in the first distance partition array and the offset distance partition array, each comprising a non-zero value: adding the first distance partition array to the offset distance partition array to produce a summed distance partition array; and determining that a first value in the summed distance partition array associated with the first Doppler partition is equal to or greater than two.

[0026] In some respects, the techniques described herein relate to a method that further includes: determining two neighboring Doppler partitions in the summed distance partition array, each associated with a value equal to or greater than one in the summed distance partition array; and setting the value associated with the two neighboring Doppler partitions in the distance partition array to zero to produce the corrected distance partition array. Attached Figure Description

[0027] A more complete understanding of the subject matter can be obtained by referring to the specific embodiments and claims considered in conjunction with the following figures, in which similar reference numerals refer to similar elements in each figure.

[0028] Figure 1 A block diagram of a DDM MIMO automotive radar system is shown.

[0029] Figure 2 A timing diagram is drawn that can be used to determine the sequence of signals transmitted by the DDM-MIMO radar system.

[0030] Figure 3 A plot depicting the Doppler spectrum of a uniform DDM-MIMO radar system as a function of radian frequency (and Doppler shift).

[0031] Figure 4 It is a flowchart depicting a method for processing raw data corresponding to sampled return signals, which correspond to the reflection of transmitted signals by objects in the environment surrounding the DDM-MIMO radar system.

[0032] Figure 5 An example of the distance-Doppler matrix of the coherent integral is shown.

[0033] Figure 6 It is a graph depicting the Doppler spectrum of a uniform DDM-MIMO radar system as a function of radian frequency (and Doppler frequency shift), where signals from two objects overlap within a specific Doppler partition.

[0034] Figure 7 It is a graph depicting the Doppler spectrum of a uniform DDM-MIMO radar system as a function of radian frequency (and Doppler frequency shift), where for two objects, the signals within a particular Doppler partition are adjacent to or partially overlap each other.

[0035] Figure 8A It is a graph depicting MIMO array data, where the first object has a signal magnitude significantly larger than the signal associated with the second object.

[0036] Figure 8B It is a description Figure 8A A graph of the MIMO array data of the second object, where object 1 has a signal magnitude significantly larger than that associated with object 2.

[0037] Figure 8C and 8D Each shows the following according to this disclosure Figure 8A and 8B MIMO data for Object 1 and Object 2, where the signal overlap region has been set to zero.

[0038] Figure 8E and 8F Depict separately the modifications made to account for signal overlap. Figure 8A and 8B Signals for objects 1 and 2.

[0039] Figure 9This is a graphical depiction of the method of the present invention for detecting overlapping object signals within RDBM data and mitigating data corruption caused by such overlap.

[0040] Figure 10 This is a flowchart depicting a method for detecting and mitigating Doppler spectral overlap in a DDM MIMO radar system RDBM.

[0041] Figure 11 It provides Figure 10 The steps of the method are represented graphically.

[0042] Figure 12 An example summed distance-Doppler image and corresponding bitmap 1204, which can be generated by the bitmap generation method according to the present invention, are depicted.

[0043] Figure 13 This is a flowchart depicting a method for detecting signal overlap in a portion of the Doppler spectrum in a DDM MIMO radar system RDBM and mitigating the overlap based on the magnitude of the overlapping signal.

[0044] Figure 14 It provides Figure 13 The steps of the method are represented graphically. Detailed Implementation

[0045] The following detailed description is illustrative in nature only and is not intended to limit the embodiments of the subject matter of the application or the use of such embodiments. As used herein, the terms "exemplary" or "example" mean "serving as an example, instance, or illustration." Any embodiment or example described herein as exemplary or illustrative should not be construed as preferred or advantageous over other embodiments. Furthermore, there is no intention to be bound by any express or implied theory presented in the foregoing technical field, background art, or the following detailed description.

[0046] Automotive radar systems are used to support advanced driver assistance systems (ADAS) functions such as assisted cruise control, emergency braking, blind spot monitoring, and alerts.

[0047] The various embodiments described herein relate to a Doppler partitioning multiplexing (DDM) multiple-input multiple-output (MIMO) radar system with integrated object tracking capabilities, including the ability to determine the direction of arrival (DOA) of a detected object.

[0048] In one or more embodiments, an example radar system includes a microcontroller unit (MCU) having a signal processor configured to generate a range-Doppler dataset from, for example, raw analog-to-digital (ADC) samples derived from returned signals (i.e., reflections), the returned signals corresponding to reflections of transmitted signals (e.g., chirps) transmitted via a transmitter (TX) antenna element of the radar system (e.g., according to a Doppler partitioning scheme having, for example, a uniform pulse repetition interval (PRI),) received via a receiver (RX) antenna element of the radar system. For example, the range-Doppler dataset can be generated by performing range compression (e.g., in the form of a fast-time Fast Fourier Transform (FFT)) and Doppler compression (e.g., in the form of a slow-time FFT) on raw ADC samples from one or more ADC outputs of the radar system's receiver module. The signal processor can then perform per-channel DOA estimation by performing a channel-dimensional FFT on each range-Doppler unit of the range-Doppler dataset to produce a corresponding FFT output matrix for each range partition. The signal processor can then perform DDM decoding based on the FFT output matrix to produce a decoded range-Doppler bitmap (RDBM), where each row of the RDBM corresponds to a corresponding FFT output matrix of the FFT output matrix, and thus to a corresponding distance partition of the range-Doppler dataset. While one or more embodiments described herein involve the use of FFT, it should be understood that this is intended to be illustrative and not limiting. According to one or more other embodiments, other suitable techniques for performing the Discrete Fourier Transform (DFT) may alternatively be used.

[0049] Standard DDM MIMO technology means that all radar system transmitters are active in the same time frame, with each transmitter having a distinct self-induced chirp-to-chirp phase rotation while maintaining a common and constant pulse repetition frequency (PRF). This produces orthogonal sequences of signals transmitted from each transmitter module in the Doppler domain, such that the returned signal received from each object replicates at different rates in the Doppler domain, depending on the transmitter module (or TX channel) associated with the returned signal. The manner in which these replications occur in the Doppler domain is determined by DDM codes, and the order of replication is required to correctly construct the MIMO array. Finding the order of such replicated signals in the Doppler domain can be called "decoding," which is equivalent to finding the corresponding object in... Unambiguous velocity within the unambiguous Doppler range, where It is the pulse repetition interval (PRI).

[0050] Existing solutions for DDM decoding rely on detection algorithms that are susceptible to channel overlap errors from various Doppler velocity separation copy signals present in the Doppler domain. The likelihood of such overlap (resulting in erroneous values) can increase, for example, in the case of close-range and / or high-speed objects. Overlapping object signals can cause consistent ghosting spurious signals across multiple frames and can affect DOA estimates, thereby impacting vehicle ADAS decision-making.

[0051] To mitigate these signal overlap errors, this disclosure provides a vehicle radar system including a signal processing chain configured to detect potential overlap occurring within a range-Doppler data frame. Data values ​​associated with the overlapping signal values ​​within the data frame can then be zeroed out to remove corrupted range-Doppler cell values ​​from the data frame. In the case of a uniform linear array (ULA) array, these eliminated values ​​can be recovered via autoregressive (AR) extrapolation within a MIMO array, and in the case of a sparse array (SPA), the dictionary and steering vector can be updated by removing (e.g., zeroing out) associated rows or columns from the data frame.

[0052] In some embodiments, since the reflected signal from a smaller object (i.e., an object with a relatively small radar cross-section compared to other detected objects) may have a weakened or negligible effect in the overlapping signal compared to a larger object in the RDBM, this disclosure provides embodiments that compensate only for the effect of the strongest object (i.e., the object with the largest detected signal in the RDBM) on the signal from the weaker object while ignoring the effect of the smaller object on the larger object.

[0053] In specific embodiments of this disclosure, the signal processor of the radar system is configured to detect cells in a range-Doppler dataset (e.g., RDBM) that store values ​​resulting from signal overlap occurring within the processed range-Doppler dataset. The signal processor may then zero out or otherwise modify the values ​​of these cells to reduce the detrimental effects of such overlap. In one example, the signal processor is configured to process the range-Doppler dataset by adding shifted copies of the range-Doppler dataset itself to create a summed range-Doppler dataset, wherein the range-Doppler dataset copies constituting the summed dataset are shifted according to the radar system's DDM code, which determines the TX interval in the Doppler partition.

[0054] In the case of a range-Doppler dataset containing binary data (e.g., cells in the range-Doppler dataset contain a value '1' when a signal is present and a value '0' when a signal is absent), such bitmap addition should not result in any cell in the summed bitmap containing a value greater than '1' if there is a sufficient Doppler partitioning interval between the signals contained in the range-Doppler dataset—that is, cells in the summed bitmap should not contain a value '2', as this would indicate that the two signals (i.e., the two cells with a value '1') overlap. If cells in the summed range-Doppler dataset have a value of '2' or greater, this indicates signal overlap, and appropriate actions can be taken to mitigate the effects of such overlap.

[0055] Figure 1 A block diagram of a DDM MIMO automotive radar system 100 is shown, including a DDM MIMO radar device 102 connected to a radar microcontroller unit (MCU) 104. In one or more embodiments, device 102 may be a linear frequency modulated (LFM) DDM MIMO radar device. In one or more embodiments, DDM MIMO radar device 102 may be embodied as a field-replaceable unit (LRU) or modular component designed for rapid replacement at the operating location. Similarly, radar MCU 104 may be embodied as a field-replaceable unit (LRU) or modular component. Although a single or monostatic DDM MIMO radar device 102 is shown, it should be understood that additional distributed radar devices can be used to form a distributed or multistatic radar. Furthermore, the depicted radar system 100 may be implemented as an integrated circuit, wherein the DDM MIMO radar device 102 and radar MCU 104 are formed as separate integrated circuits (chips) or single chips, depending on the application.

[0056] The radar device 102 includes one or more transmit antenna elements 126 (sometimes referred to herein as “transmit antenna 126”) and receive antenna elements 142 (sometimes referred to herein as “receive antenna 142”) connected to one or more radio frequency (RF) transmitter (TX) modules 118 and receiver (RX) modules 128, respectively. Each transmit antenna 126 and TX module may be designated herein as TX1, TX2, TX3, ... TX i A corresponding transmit channel in a set of transmit channels is associated with each transmit channel, where "i" is the total number of transmit (TX) channels. Each receive antenna 142 and RX module 128 may be associated with a corresponding transmit channel designated herein as RX1, RX2, RX3, ... RX jA set of corresponding receive channels are associated, where “j” is the number of receive (RX) channels. As a non-limiting example, a radar device (e.g., radar device 102) may include individual antenna elements (e.g., antenna element 126) respectively connected to four transmitter modules (e.g., transmitter module 118) and sixteen receiver modules (e.g., receiver module 128). These quantities of transmitter and receiver antenna elements and modules are intended to be illustrative and not limiting, wherein other quantities of these elements are possible in one or more other embodiments, such as four transmitter modules 118 and six receiver modules 128, or a single transmitter module 118 and / or a single receiver module 128. Radar device 102 includes a chirp generator 116 configured to supply a chirped input signal to transmitter module 118. To this end, the chirp generator 116 is configured to receive input program and control signals from the MCU 104 via a digital-to-analog converter 114. As a non-limiting example, the input program and control signals include a reference local oscillator (LO) signal, a chirp start trigger signal, and a program control signal. The chirp generator 116 is configured to generate a chirp signal and send it to the transmitter module 118 for transmission via the transmit antenna element 126. In one or more embodiments, each transmitter module includes a phase rotator 120 (sometimes referred to herein as "phase shifter 120") configured to apply phase encoding to the chirp signal, wherein the phase rotator 120 is controlled by program control signals generated by the MCU 104. In one or more embodiments, the phase rotator 120 may provide a uniform phase shift between the transmitter modules 118. According to one or more other embodiments, alternatively, the phase rotator 120 may provide each transmitter module 118 with the ability to implement progressive phase shifting using a non-uniform encoding technique. Each transmitter module 118 includes an RF conditioning module 122 configured to filter the phase-coded chirped signal.

[0057] Each transmitter module 118 includes a power amplifier 124 configured to amplify the filtered phase-coded chirped signal before it is provided to and transmitted via one or more corresponding transmit antenna elements 126. By transmitting a progressively phase-shifted sequence of chirped signals using each transmit antenna 126, each transmitter module 118 operates in a Doppler-division multiplexing manner with other transmitter modules in the same module 118, as these transmitter modules are programmed to simultaneously transmit the same waveform on a phase-separated schedule. Throughout this document, the transmitted chirped signal is sometimes referred to as the “transmitted signal”.

[0058] Radar signals transmitted by transmitter antenna module 118 can be reflected by objects in the environment of radar device 102 (i.e., "target objects"), and a portion of the reflected radar signal, sometimes referred to herein as "return signal" or "reflection," is received by receiver antenna module 128 at radar device 102. At each receiver module 128, the received (RF) antenna signal is amplified by low-noise amplifier (LNA) 140 and then fed to mixer 138, where the received (RF) antenna signal is mixed with a transmitted chirp signal generated by RF conditioning module 122. The resulting intermediate frequency signal is fed to high-pass filter (HPF) 136. The resulting filtered signal is fed to variable gain amplifier 134, which amplifies the signal before feeding it to low-pass filter (LPF) 132. This re-filtered signal is fed to analog-to-digital converter (ADC) 130 and output as a digital signal by each receiver module 128 (e.g., output to signal processor 110 of MCU 104). In this manner, receiver module 128 compresses target echoes with various delays into multiple sinusoidal frequencies, the frequencies of which correspond to the round-trip delay of the echoes.

[0059] In radar system 100, radar MCU 104 may be connected and configured to supply input control signals to radar device 102 and receive digital output signals generated by receiver module 128 therefrom. In one or more embodiments, radar MCU 104 includes radar controller 108 and signal processor 110, wherein either or both of radar controller 108 and signal processor 110 may be embodied as a microcontroller unit (MCU) or other processing unit. Radar controller 108 may receive data from radar device 102 (e.g., from receiver module 128) and may control radar parameters of radar device 102 via DAC 114, such as the frequency band, length, etc. of each radar frame. For example, DAC 114 may be used to adjust the radar chirp signal output from chirp generator 116 included in radar device 102. Signal processor 110 may be configured and arranged for signal processing tasks, such as, but not limited to, object identification, calculation of interval or distance to an object, calculation of the radial velocity of an object, and calculation of the DOA of a signal reflected by an object. In this document, the term "DOA" or "direction of arrival" (sometimes referred to as "AoA" or "angle of arrival") refers to the angle of a signal (e.g., a radar signal) reflected by an object in the environment. Signal processor 110 may provide calculated values ​​associated with such calculations to storage device 112 and / or other systems via interface 106.

[0060] As a non-limiting example, interface 106 enables MCU 104 to communicate with other systems via local area networks and wide area networks, the Internet, automotive communication buses, and / or other types of wired or wireless communication systems. In one or more embodiments, MCU 104 can provide calculated values ​​to other systems via interface 106, such as radar-camera-lidar fusion systems; automated driving assistance systems including parking, braking, or lane-changing assist features; and so on. Storage device 112 can be used to store instructions for MCU 104, data received from radar device 102, calculated values ​​from signal processor 110, etc. Storage device 112 can be any suitable storage medium, such as volatile or non-volatile memory.

[0061] To control transmitter module 118, radar controller 108 may be configured, for example, to generate transmitter input signals, such as program, control trigger, reference LO signal, calibration signal, and spectrum shaping signal (e.g., ramp generation in the case of FMCW radar). The radar controller may be configured, for example, to receive data signals for RF (radio frequency) circuit enable sequences, sensor signals, and / or register programming or state machine signals. In one or more embodiments, radar controller 108 may be configured to program transmitter module 118 with transmitter input signals to operate in a DDM manner by progressively phase-shifting the LFM chirp to be transmitted by transmit antenna element 126. In a selected embodiment, radar controller 108 is configured to progressively phase-shift the LFM chirp output by chirp generator 116 using coprime coding (CPC) encoding by programming programmable phase rotator 120 prior to transmission. Each transmitter module 118 transmits a transmit channel signal having different CPC-coded LFM signals generated using a programmable slow-time phase rotator 120, such that the receiver module 128 can adjust the object return signal (i.e., the return signal corresponding to the reflection of the transmit signal transmitted via the transmit antenna element 126 from one or more objects, wherein the return signal is then received via the receive antenna element 142) to generate a digital domain signal, which is processed by the radar MCU 104 to separate and identify the CPC-coded transmit channel signal.

[0062] At each receiver module 128, a digital output signal is generated from the target return signal for digital processing by the signal processor 110 to construct and accumulate a multiple-input multiple-output (MIMO) array vector output, thereby forming a MIMO aperture for calculating DOA estimates and plotting or mapping maps of the object trajectory. Specifically, in the signal processor 110, the digital output signal may be processed by one or more Fast Fourier Transform (FFT) or Discrete Fourier Transform (DFT) modules, such as a fast-time (range) FFT module for generating a range-chilled antenna cube (RCAC) and a slow-time (Doppler) FFT module for generating a range-Doppler antenna cube. The per-channel DOA estimation module of the signal processor 110 may then perform a corresponding channel-dimensional FFT on each range partition of the range-Doppler antenna cube to produce several FFT or DFT output matrices (i.e., one FFT or DFT output matrix for each range partition of the range-Doppler antenna cube). The DDM decoder module of signal processor 110 can then generate a decoded distance-Doppler bitmap (RDBM) based on the FFT or DFT output matrix, as described in more detail below. The decoded RDBM can be further processed by signal processor 110 to construct a DDM MIMO array vector, which is then processed by signal processor 110 to perform DOA estimation and object tracking. MCU 104 can then output the resulting object trajectory (e.g., via interface 106) to other automotive computing devices or user interface devices for further processing or display.

[0063] In order to, for example Figure 1 To understand the operation of the DDM MIMO radar system of radar system 100 in context, refer now to the timing diagram 200 shown. Figure 2 The timing diagram 200 illustrates four transmitters using a uniform Doppler partitioning scheme (e.g., in one or more embodiments, each transmitter corresponds to...). Figure 1 The linear chirped transmission schedules 201, 202, 203, and 204 of the transmitter module 118 and the transmitting antenna element 126 are configured. Each transmitter is associated with a corresponding transmitting channel in the transmitting channels TX1-TX4 and is programmed to simultaneously transmit a DDM linear chirped waveform sequence within a single radar transmission frame. Each transmitter transmits the linear chirped waveform (e.g., 201A, 201B) at a fixed and uniform pulse repetition frequency (PRF) rate, the PRF rate being the reciprocal of the pulse repetition interval (e.g., PRF = PRI). -1 ) or the reciprocal of the chirping interval (e.g., PRF=CIT) -1Additionally, each transmitter encodes each chirp with an additional asymptotic phase shift using a phase rotator in the front-end circuitry. As a result of this asymptotic phase shift encoding, each received chirp corresponding to the reflection of the radar signal originating from each different transmitter effectively has a different zero radial velocity Doppler shift, and individual object detections can be associated with the corresponding transmitter from which the reflected radar signal originated, which is necessary for the correct operation of the subsequent MIMO virtual array construction.

[0064] Based on the following equation, the position of zero radial velocity is controlled by an asymptotic phase offset of the chirp applied to each transmitter:

[0065]

[0066] Where f zrv,i It is the zero radial velocity Doppler shift frequency of transmitter i, and where A i It is the asymptotic phase shift (in radians) between two adjacent chirps. For example, in a 4-TX DDM MIMO radar system, each transmitter can be assigned the following asymptotic phase shift, and therefore a zero radial velocity frequency:

[0067]

[0068]

[0069]

[0070]

[0071] In this example, the result is described as follows: for transmission channel TX1, the first transmitter encodes its chirped waveform with a 0-degree asymptotic phase offset; for transmission channel TX2, the second transmitter encodes its chirped waveform with a 90-degree asymptotic phase offset; for transmission channel TX3, the third transmitter encodes its chirped waveform 20 with a 180-degree asymptotic phase offset; and for transmission channel TX4, the fourth transmitter encodes its chirped waveform with a 270-degree asymptotic phase offset. In a DDM MIMO radar system using uniform Doppler partitioning, an object can be explicitly associated with the correct transmitter and TX channel by determining its position within the sectored Doppler spectrum, provided that the object has ±PRF / (2N) before applying DDM. ch The true Doppler frequency shift within ) where N ch This is the number of DDM transmitter channels.

[0072] To illustrate the principle of Doppler peak detection and transmitter correlation, refer now to Figure 3 The figure depicts the effect of a uniform DDM-MIMO radar system (e.g., Figure 1 A plot of the Doppler spectrum of the radar system 100 (an example embodiment) with varying radian frequencies (and Doppler shifts) is provided, where the maximum radial velocity of the object does not exceed the allocated spectral budget, thus generating a non-ambiguous correlation between the target peak and the transmitting antenna. As depicted, each transmitter channel TX1-TX4 has a corresponding allocated spectral segment 311, 312, 313, 314 centered at the corresponding zero radial velocity frequencies (e.g., 0, π / 2, π, and 3π / 2). Therefore, for each transmitter channel TX1-TX4, there is ±PRF / (2N) at the zero radial velocity frequency. ch The object measurements 301, 302, 303, and 304 of the true Doppler frequency shift within the sectored Doppler spectrum 300 can be definitively associated with the correct transmitter by determining the position of the object measurement within the sectored Doppler spectrum 300. This result holds true when the radial velocity of the object falls within the spectral budget segments 311, 312, 313, and 314 allocated to each transmitter channel TX1-TX4. As shown, the spectral budget segment 311 of transmitter channel TX1 can be divided into segment 311A, which occurs at the beginning of the time period, and segment 311B, which occurs at the end of the time period.

[0073] In the case of existing monolithic microwave integrated circuits (MMICs) for 76-81 GHz fast-chirped automotive radar front-ends, the fastest chirped signal is limited by a chirped interval time (CIT) of not less than approximately 15 microseconds. Therefore, for such radar systems, the maximum unambiguous Doppler radial detection velocity is ±65 m / s (or ±234 km / hr), and then the entire range of detectable velocities is limited to N. ch The transmitters and transmission channels are divided into N. ch The system requires a segment for unambiguous DDM operation. In high-dynamic driving scenarios where the object and radar are traveling at speeds of 100 km / hr or faster, a Doppler spectral bandwidth of approximately 470 km / hr is sufficient for only a very small number of transmitters. While more transmitters and DDM transmitter channels can be supported without introducing ambiguity by significantly shortening the CIT (Current Ingress Time) to microseconds, it should be noted that such ultrashort chirps increase the cost and complexity of the radar system given these high-dynamic driving conditions.

[0074] Figure 4 This illustrates an illustrative process flow of method 400 according to the present disclosure, by which raw data corresponding to the sampled return signal and the transmitted signal (e.g., a chirp transmitted according to a DDM scheme, for example...) are compared. Figure 2The timing diagram 200 shows a chirp-related reflection, which is caused by objects in the environment surrounding the DDM-MIMO radar system. As described herein, method 400 is configured to detect signal overlap occurring with the processed RDBM of the radar system and mitigate the detrimental effects of such overlap on the DOA estimation output of the radar system.

[0075] According to one or more embodiments, method 400 can be performed using any one or both of the radar controller and signal processor of the radar MCU. Reference Figure 1 The elements of radar system 100 described in method 400 are used to illustrate this method. However, it should be understood that this is illustrative and not limiting, at least because other suitable radar systems may be used to perform method 400 in one or more other embodiments.

[0076] At box 402, the signal processor 110 of the MCU 104 of the radar system 100 receives raw sample data (sometimes referred to as "ADC samples") from one or more ADCs 130 of the receiver module 128. These ADC samples can be output as digital signals by the ADC 130. These ADC samples represent signals corresponding to those transmitted by the transmitter module 118 via the transmit antenna element 126 (e.g., according to the DDM scheme, for example...). Figure 2 The received signal (sometimes referred to as the "reflected signal" or "return signal") is a reflection of the transmitted signal (i.e., the chirp) sent by the DDM scheme shown in timing diagram 200, wherein the transmitted signal is reflected from one or more objects in the environment of the radar system 100. The return signal is received by the receiver module 128 via the receiving antenna element 142.

[0077] At block 404, signal processor 110 performs range compression of the original ADC sample, for example, by performing a fast-time FFT or DFT on the original ADC sample. Signal processor 110 may generate a range-chilled antenna cube (RCAC) as the output of this fast-time FFT or DFT.

[0078] At box 406, signal processor 110 performs Doppler compression of RCAC, for example, by performing a slow-time FFT or DFT on the RCAC. Signal processor 110 may produce a range-Doppler antenna cube as the output of this slow-time FFT or DFT. The range-Doppler antenna cube may be a three-dimensional array of dimensions m×n×p, where m represents the number of Doppler partitions, n represents the number of range partitions, and p represents the number of RX channels represented in the range-Doppler antenna cube (e.g., corresponding to the number of receiving antenna elements 142 or the number of receiver modules 128). In this document, p is sometimes referred to as the “channel dimension” in the context of the range-Doppler antenna cube and the range partition matrix extracted from it.

[0079] Each element of the range-Doppler antenna cube can encode the complex amplitude of the received signal for a specific range partition, Doppler partition, and RX channel. In one or more embodiments, a given RX channel slice of the range-Doppler antenna cube can be represented as a two-dimensional (2D) array of range-Doppler elements, wherein the complex amplitude of each element corresponds to the average complex amplitude within the region boundary in Cartesian space via corresponding pairs of equidistant Doppler lines and equidistant lines. That is, the boundary of each range partition is defined by a corresponding pair of equidistant lines, and the boundary of each Doppler partition is defined by a corresponding pair of equidistant Doppler lines. Each range-Doppler element corresponds to a corresponding Doppler partition and range partition pair.

[0080] Because transmitter module 118 transmits chirps simultaneously in the DDM-MIMO radar system, information from all TX channels is represented in each element of the range-Doppler antenna cube. Each range partition represents the distance or interval between the radar system and the object. Each Doppler partition represents a Doppler frequency shift value corresponding to the velocity the object may be traveling at (e.g., its own velocity relative to radar system 100). Such velocity can be calculated based on the determined Doppler frequency shift associated with the object.

[0081] At block 408, signal processor 110 performs per-channel (e.g., per RX channel) DOA estimation using a range-Doppler antenna cube. In one or more embodiments, signal processor 110 performs per-channel DOA estimation by extracting range partitions from the range-Doppler antenna cube and performing a channel-dimensional FFT or DFT on each range-Doppler cell of the extracted range partition to produce an FFT or DFT output matrix (i.e., where each FFT or DFT output matrix corresponds to a corresponding range partition of the range-Doppler antenna cube).

[0082] At block 410, signal processor 110 performs DDM decoding of the range-Doppler antenna cube based on the FFT or DFT output matrix generated by the per-channel DOA estimation performed at block 408 to produce a decoded RDBM. At block 411, the RDBM is processed as described herein to determine whether the RDBM encodes values ​​associated with overlapping DDM signals, and if so, those values ​​may be zeroed or otherwise manipulated to reduce the impact of such overlapping signals on further DOA estimation.

[0083] At block 412, signal processor 110 constructs a virtual MIMO array based on the decoded RDBM and range-Doppler antenna cube. At block 413, lost sample values ​​can be recovered, for example, by applying an autoregressive algorithm (e.g., attributed to the zeroing that occurred previously in step 411). If such data has been recovered, at block 414, signal processor 110 uses the virtual MIMO array to generate object location data based on DOA estimation.

[0084] At box 416, signal processor 110 generates object tracking data based on object location data.

[0085] During operation, the signal processor 110 of radar system 100 generates a range partition matrix from (e.g., generated at box 404 above) a range-Doppler antenna cube, and performs a channel-dimensional FFT on each range-Doppler element of the extracted range partition matrix to produce an FFT output matrix. The FFT output matrix is ​​used to generate a Doppler partition maxima array, which represents the maximum value detected in each column of the FFT output matrix. The maxima array can then be combined to generate a coherent integral RDM. Herein, RDM may differ from RDBM in that an RDBM comprises a matrix or 2D array of binary values ​​(e.g., 0s and 1s), while an RDM may comprise a matrix or 2D array of signal amplitudes. Figure 5 An example of such a coherent integration RDM 500 is shown. In the coherent integration RDM 500, data from each TX channel is encoded according to the corresponding DDM code for each TX channel, such that each TX channel dataset is represented in the RDM 500 and offset by a predetermined number of Doppler partitions, where the offset is different for each TX channel (e.g., as defined by the corresponding DDM code). Figure 5 The multiple Doppler partitions 502 depicted represent data corresponding to different transmitters. For example, data corresponding to the first TX channel TX1, representing a speed of approximately -30 m / s, is set in the first Doppler partition 502. Data corresponding to the second TX channel TX2, representing a speed of approximately -28 m / s, is set in the second Doppler partition 502.

[0086] In an ideal coherent integral RDM 500, there is sufficient Doppler offset between various Doppler partitions 502 such that the signals depicted therein do not overlap with each other. However, in cases involving relatively high-speed objects, signals associated with a particular TX channel that typically do not overlap with signals in other TX channels and may be confined to a particular Doppler partition may extend and overlap, thereby impairing signals associated with other TX channels in other Doppler partitions.

[0087] This phenomenon Figure 6The figure depicts a plot of the Doppler spectrum of a uniform DDM-MIMO radar system as a function of radian frequency (and Doppler shift), where signal overlap exists for two objects (i.e., object 1 and object 2) within a specific Doppler partition. Specifically, peaks 602, 604, and 606 represent the received signal associated with the first object in the associated Doppler partition, while peaks 608, 610, and 612 represent the received signal associated with the second object in the associated Doppler partition. As shown, within Doppler partition 614, signal 606 associated with object 1 and signal 610 associated with object 2 overlap and combine. The depicted overlap may occur, for example, due to the relatively high velocity of one or more of objects 1 and 2. As described herein, such overlap may reduce the fidelity of the signal within the corresponding RDM or RDBM and may reduce the accuracy of DOA estimates associated with both objects 1 and 2.

[0088] Such signal degradation can occur even if the signals associated with two or more objects do not precisely overlap within a specific Doppler region. For example, signals that are adjacent to each other in the Doppler domain may similarly suffer signal degradation and / or damage due to the sidelobe values ​​associated with the object signals. To illustrate, Figure 7 A plot depicting the Doppler spectrum of a uniform DDM-MIMO radar system as a function of radian frequency (and Doppler shift), where for two objects (i.e., object 1 and object 2), the signals in a specific Doppler region are adjacent to each other. Specifically, in Figure 7 In the diagram, peaks 702, 704, and 706 represent the received signals associated with the first object in the associated Doppler partition, while peaks 708, 710, and 712 represent the received signals associated with the second object in the associated Doppler partition. As shown, within Doppler partition 714, signal 706 associated with object 1 and signal 710 associated with object 2 are adjacent to each other. Even if the signals do not overlap precisely, the sidelobes associated with the signals of object 1 and object 2 may overlap, resulting in a decrease in the fidelity of these signals. This, in turn, may reduce the accuracy of the DOA estimation associated with both object 1 and object 2.

[0089] exist Figure 6 and 7 In this context, the magnitude of the peak of the triangle represents the magnitude of the corresponding signal. It should be recognized in this disclosure that when signals associated with two objects overlap or are adjacent to each other (as described above regarding...), Figure 6 and 7As described, overlapping signals with larger magnitudes may have a greater distortion effect on signals with smaller magnitudes, while signals with smaller magnitudes may have a smaller distortion effect on overlapping signals with larger magnitudes. In this case, the method of the present invention can be used to remove the overlap effect when performing DOA estimation on objects associated with lower magnitude signals, but can be ignored when performing DOA estimation on objects associated with higher magnitude signals. This is in Figure 8A and 8B Described in the text.

[0090] Specifically, Figure 8A MIMO array data is depicted, wherein the signal associated with a first object at least partially overlaps with the signal of a second object, wherein the second signal is substantially larger than the signal of the first object (e.g., having an amount greater than or equal to the signal of the first object). As shown, the signal associated with the first object (typically similar to...) Figure 8A The signal in region 802 is significantly distorted in the overlapping regions, as depicted by the peak in region 804. This distortion produces two significant peaks in the MIMO data, which could otherwise make it difficult to extract the signal from the data. Figure 8A Extract the signal associated with the first object from the data (e.g., having Figure 8A (The signal in area 802).

[0091] on the contrary, Figure 8B The MIMO array data of the second object is depicted, wherein the signal associated with the second object at least partially overlaps with the signal of the first object, and wherein the signal of the second object is substantially larger than the signal of the first object (e.g., having a magnitude greater than or equal to the signal of the first object). As shown, the signal associated with the first object is largely unaffected by signal overlap, which is reflected in... Figure 8B In regions 810, there are small perturbations. Therefore, in embodiments of this disclosure, when a signal with a much larger magnitude (e.g., 10 times or more) overlaps with a second smaller signal, the signal overlap can be ignored because the smaller signal does not represent a significant distortion of the larger signal.

[0092] To mitigate this problem, this disclosure provides a method for detecting such overlap (or neighboring object signals) such that the overlap data can be ignored or alternatively modified to take signal overlap into account. Figure 8C and 8D Each shows the following according to this disclosure Figure 8A and 8B The MIMO data of Object 1 and Object 2, wherein the signal overlap region has been zeroed. By zeroing these regions according to this disclosure, the original signals associated with Object 1 and Object 2 can be recreated, as shown below. Figure 8E and 8F As shown.

[0093] To further illustrate this disclosure, Figure 9 This is a graphical depiction of the method of the present invention for detecting object signal overlap within RDM or RDBM data and mitigating data corruption caused by such overlap. Figure 9 In this context, the range-Doppler cube 902 includes data for a first object. As shown, the vertical and horizontal directions of the first RDM of the first range-Doppler cube 902 represent the Doppler and range dimensions of the signal associated with the first object, respectively. Different layers of the range-Doppler cube 902 represent signals associated with different receiver RX channels within the range-Doppler cube 902. As depicted, across different channels (i.e., RX1, RX2, and RX3), signals associated with the first object (e.g., TX signals 950, 952, and 954) are identified in different Doppler partitions (generated by different Doppler partitioning schemes applied at each transmitter).

[0094] like Figure 9 As depicted, the range-Doppler cube 902 also includes data on a second object. As depicted, the second object (e.g., signals 956, 958, and 960) is identified across different receiver channels (i.e., RX1, RX2, and RX3) in different Doppler partitions (generated by different Doppler partitioning schemes applied at each transmitter).

[0095] When the signals of object 1 and object 2 are shown together in the range-Doppler cube 902, it is apparent that there is an overlap 908 between the signal for object 1 generated by the signal transmitted by transmitter TX2 (e.g., signal 952) and the signal for object 2 generated by the signal transmitted by transmitter TX1 (e.g., signal 956). As described herein, this overlap may introduce inaccuracies into the estimated DOA of object 1 and / or object 2.

[0096] Given a theoretical version of the distance-Doppler cube 902 containing only data for object 1, a data array 910 representing an object 1 MIMO array can be generated, which combines the object 1 data associated with transmitted signals TX1, TX2, and TX3 at a given distance (i.e., the distance where object 1 is located). Similarly, for a hypothetical distance-Doppler cube 902 containing only data for object 2, a similar data array 912 can be generated for object 2 data at a given distance (i.e., the distance where object 2 is located). Data arrays 910 and 912 can then be processed to estimate the DOA of object 1 and object 2.

[0097] However, since the signals for both object 1 and object 2 exist within the range-Doppler cube 902 and those signals overlap 908, it is impossible to generate such arrays for objects 1 and 2 by extracting data from the range-Doppler cube 902. Instead, the MIMO array 914 for object 1 at a specific distance within the range-Doppler cube 902 will include some data corrupted due to overlap 908 (indicated by dashed circle 918). Similarly, the MIMO array 916 for object 2 at that distance within the range-Doppler cube 902 will include some data corrupted due to overlap 908 (indicated by dashed circle 920).

[0098] The system of the present invention is configured to detect corrupted data in each MIMO array 916 and 918 and set the corrupted values ​​to zero (see MIMO arrays 922 and 924). In the case of corrupted values ​​being set to zero, the system of the present invention can use various techniques (e.g., autoregressive analysis) to replace or reconstruct the zeroed values ​​to form complete MIMO arrays 926 and 928 for object 1 and object 2, respectively.

[0099] In a similar manner, as described herein, the system of the present invention can detect potential data corruption caused by partial overlap of signals from different objects occurring within the same Doppler partition of an RDM or RDBM.

[0100] Figure 10 This is a flowchart depicting a method 1000 for detecting Doppler spectral overlap in a DDM MIMO radar system RDM and / or RDBM. Method 1000 can be implemented to perform the above-described... Figure 4 All or part of the described block 411. According to one or more embodiments, method 1000 can be performed using either or both of the radar controller and signal processor of the radar MCU (e.g., radar controller 108 and / or signal processor 110). Therefore, refer to... Figure 1 The elements of the radar system 100 described in the method 1000 are used to illustrate the method 1000. However, it should be understood that this is illustrative and not limiting, at least because other suitable radar systems may be used to perform the method 1000 in one or more other embodiments. Figure 11 It is a diagram that provides a graphical representation of the steps of method 1000.

[0101] Method 1000 describes an inventive method for detecting Doppler signal overlap that may include, for example, a specific range-Doppler matrix or dataset, such as an RDBM. At block 1002, an initial range value is determined. Typically, this initial range value will be the minimum range value of the radar system; however, in other embodiments, any range value corresponding to the range value of the radar system's range-Doppler antenna cube may be selected as the initial range value.

[0102] At box 1004, define the input in the form of a two-dimensional dataset. The dataset may include distance slices of the distance-Doppler cube obtained at the distance values ​​defined at box 1002. Figure 11 Table 1102 is a representation of the two-dimensional input dataset of box 1004.

[0103] At box 1006, a range-Doppler array is defined as a one-dimensional array containing binary values ​​decoded from a two-dimensional dataset of the first receiver RX (e.g., referring to Table 1102, the range-Doppler array defined at box 1006 is equivalent to array 1104, which is the array decoded from Table 1102). The one-dimensional range-Doppler array contains binary values ​​indicating the presence of a received signal at different Doppler velocities for the first receiver RX signal. Specifically, a '1' value in a cell of the one-dimensional range-Doppler array will indicate the presence of an object signal at the range-Doppler combination associated with that particular cell. Conversely, a '0' value in a cell of the one-dimensional range-Doppler array will indicate the absence of an object signal at the range-Doppler combination associated with that particular cell. Examples of such one-dimensional range-Doppler arrays are shown in... Figure 11 The image is depicted by array 1104. In this particular example, array 1104 contains only eight values ​​indicating that the radar system operates in eight different Doppler zones.

[0104] In an ideal radar system implementation, each range-Doppler array will contain only data associated with a single object within a single Doppler section. That is, a signal transmitted by a particular transmitter will not produce reflected signals that overlap with or otherwise disrupt the signals captured by other transmitters (TX). However, as discussed above, due to potential high-velocity objects or reflections from nearby objects, the reflected signal data represented in the range-Doppler array associated with a particular transmitter and object may overlap with reflected signal data in range-Doppler arrays associated with other transmitters and objects.

[0105] To detect and remedy this potential overlap, at box 1008, a set of DDM codes for the radar system is determined (typically, the DDM codes are known values ​​such that no computation is required to determine the codes—simply retrieve the DDM codes and / or the corresponding Doppler offsets associated with the codes from memory), where the DDM codes determine the Doppler intervals between the various transmitter TX signals utilized by the radar system. Using those DDM codes, the originally decoded range-Doppler array (e.g., determined at box 1006) is used to generate a set of offset range-Doppler arrays, where each new range-Doppler array is a copy of the original range-Doppler array offset in the Doppler domain by the amount determined by the DDM codes.

[0106] Therefore, at box 1010, for each DDM code in this set of DDM codes, a new range-Doppler array is created by offsetting the original range-Doppler array by the TX interval in the Doppler domain determined by the DDM code.

[0107] For example, refer to Figure 11 The example described herein illustrates that the example radar system operates using DDM codes that indicate three different TX intervals in the Doppler domain (e.g., TxDist0 representing a TX interval of 0 values ​​in the Doppler domain, TxDist1 representing a TX interval of 2 values ​​in the Doppler domain, and TxDist2 representing an interval of 5 values ​​in the Doppler domain).

[0108] Using the TX interval determined by the radar system's DDM code, a set of offset range-Doppler arrays 1106 is generated according to block 1010 of method 1000. (Reference) Figure 11 The first offset distance-Doppler array 1108 generates an offset with 0 values, the second offset distance-Doppler array 1110 generates an offset with 2 values, and the third offset distance-Doppler array 1112 generates an offset with 5 values.

[0109] At box 1012, the set of offset distance-Doppler arrays 1106 are summed together to produce a summed distance-Doppler array 1114. If the summed distance-Doppler array 1114 contains only values ​​'0' or '1', this indicates that there is no signal overlap between the various Doppler shift versions of the distance-Doppler array. However, if the summed distance-Doppler array 1114 includes values ​​equal to or greater than '2', this indicates signal overlap at that column. Therefore, in the two-dimensional input dataset, these columns are "zeroed" by setting their values ​​to zero on all transmitters to remove this signal overlap. Referring to Table 1102, for example, the columns in Table 1102 corresponding to columns containing values ​​equal to or greater than 2 in the summed distance-Doppler array 1114 are forced to zero values ​​to produce the corrected two-dimensional dataset shown in Table 1116.

[0110] In an embodiment, this zeroing can be performed by generating a bitmap that modifies the input two-dimensional dataset to remove values ​​that might cause signal overlap. Therefore, at block 1014, a bitmap is generated by determining an array having the same dimensions as the summed distance-Doppler array. The bitmap is set to value '1', where the corresponding value in the summed distance-Doppler array has a value of 0 or 1 (indicating no signal overlap), and the bitmap is set to value '0', where the corresponding value in the summed distance-Doppler array has a value of 2 or greater (indicating signal overlap). An example of the bitmap generated by block 1014 is shown below. Figure 11 Bitmap 1118.

[0111] With bitmap 1118 defined, at box 1016, the bitmap is multiplied by each row of the two-dimensional dataset to force values ​​in columns that might cause Doppler spectrum overlap to zero, while preserving the original values ​​in columns that might not cause such overlap. (Reference) Figure 11 By multiplying each row of the original input dataset (e.g., Table 1102) by bitmap 1118, a corrected two-dimensional dataset, represented by Table 1116, is produced.

[0112] At box 1018, (e.g., via a signal processor, e.g.) Figure 1 The signal processor 110 determines whether additional range values ​​(e.g., within the range-Doppler antenna cube) are available for processing. If so, the range value is incremented at box 1020, and the method returns to box 1004 to perform the same process of bitmap multiplication correction via box 1016 on a new range slice of the RDBM. However, if all range values ​​have been processed, the method terminates at box 1022. The radar system can then use the corrected data to perform DOA estimation according to the method described above.

[0113] According to method 1000, in one embodiment, overlap values ​​contained in the range Doppler image generated by the DDM MIMO radar system are identified and zeroed. In another embodiment, overlapping signals and signals adjacent to each other (i.e., partially overlapping signals) are both zeroed. For example, this modification can help remove interference and signal overlap caused by data generated from signal sidelobes.

[0114] In such embodiments, block 1014 may be implemented such that, in addition to setting the value in the bitmap to zero if the corresponding value in the summed distance-Doppler array has a value of 2 or greater (indicating signal overlap), the value in the bitmap is also set to zero if the corresponding value in the summed distance-Doppler array has a value of 1 or greater and is adjacent to a value in the summed distance-Doppler array that is also equal to 1 or greater. Figure 12 This method is described in [the document], in which Figure 12 The example summation of distances - Doppler array 1202 (e.g., with) is depicted. Figure 11The same summed distance-Doppler array 1114 (described in the figure) and a corresponding bitmap 1204 that can be generated according to the bitmap generation method of the present invention are described. As depicted, for each value in the summed distance-Doppler array 1202 that contains a value equal to or greater than 2 (which indicates signal overlap), the corresponding value in bitmap 1204 is set to the value 0, which makes the value "zeroed" from the distance-Doppler data set. In addition, for each value in the summed distance-Doppler array 1202 that contains a value equal to or greater than 1 and is adjacent to another value in the summed distance-Doppler array 1202 that has a value equal to or greater than 1 (which indicates potential or partial signal overlap), the corresponding value in bitmap 1204 is set to the value 0, which makes the value "zeroed" from the distance-Doppler data.

[0115] After construction, bitmap 1204 can be used according to box 1016 to modify the original two-dimensional input data to remove Doppler spectrum overlap values ​​and partial overlap values.

[0116] In another embodiment, the method of the present invention for Doppler spectral overlap detection and mitigation can be adjusted such that when overlap occurs, if the overlap involves a strong signal overlapping a weaker signal, the algorithm preserves the signal. (See above regarding...) Figures 8A-8F As discussed in section 9, when a strong signal overlaps with a weaker signal, the stronger signal is largely intact and can be subjected to conventional DOA processing without significantly reducing accuracy. However, if the overlap involves two signals of similar intensity, significant distortion may occur in both signals; therefore, according to the method of the present invention, these values ​​will be set to zero.

[0117] Compared to Figure 10 Method 1000, which relates to the processing of datasets containing analog data, wherein the different values ​​in the various datasets being processed include analog semaphore values, rather than binary values ​​that merely indicate the presence or absence of a signal.

[0118] Figure 13 This is a flowchart depicting a method 1300 for detecting Doppler spectral overlap in a DDM MIMO radar system RDBM and mitigating the overlap based on the magnitude of the overlapping signal. Method 1300 can be implemented to perform the above-described... Figure 4 All or part of the described block 411. According to one or more embodiments, method 1300 can be performed using either or both of the radar controller and signal processor of the radar MCU (e.g., radar controller 108 and / or signal processor 110). Therefore, refer to... Figure 1 The elements of radar system 100 described in relation to method 1300 are used to illustrate this method. However, it should be understood that this is illustrative and not limiting, at least because other suitable radar systems may be used to perform method 1300 in one or more other embodiments. Figure 14It is a diagram that provides a graphical representation of the steps of method 1300.

[0119] Method 1300 describes the method of the present invention for detecting Doppler signal overlap of a specific range-Doppler matrix. At block 1302, an initial range value is determined. Typically, this initial range value will be the minimum range value of the radar system; however, in other embodiments, any range value corresponding to the range value of the radar system's range-Doppler antenna cube can be selected as the initial range value.

[0120] At box 1304, an input in the form of a two-dimensional dataset is defined. This dataset is a two-dimensional dataset comprising analog signal quantity values ​​for different Doppler partitions and different receiver RXs for the distance values ​​defined at box 1002. Thus, the dataset may include a range-Doppler map, which can be constructed, for example, via coherent or incoherent integration between RX channels containing power / quantity levels. For example, this can be achieved by combining the decoded range-Doppler map (containing only binary values) with data stored in… Figure 5 The analog values ​​are generated by multiplying the analog values ​​in the coherent integral RDM 500.

[0121] At box 1306, a range-Doppler array is defined as a one-dimensional array containing values ​​extracted from a two-dimensional dataset of a first receiver RX for a radar system. The range-Doppler array contains analog values ​​indicating the magnitude of the received signal for the first receiver RX at different Doppler velocities. An example of such a range-Doppler array is... Figure 14 The diagram is depicted by array 1402. Array 1402 contains only eight values ​​indicating that the radar system operates in eight different Doppler zones. Values ​​a, b, and c in array 1402 represent analog signal values. In this example, the magnitude of signal c is significantly greater than values ​​a and b. As used herein, an example of a signal being "significantly" greater than the magnitude of a second signal can occur when the magnitude of the first signal is approximately 10 times greater than the magnitude of the second signal. However, the determination of when one signal is considered significantly greater than another signal may depend on a threshold that is fine-tuned or otherwise determined based on the specific implementation of the radar system. Thus, the threshold could be approximately five or 25 times greater than another signal, or it could have other values.

[0122] To detect and remedy this potential overlap, at block 1308, a set of DDM codes for the radar system is determined (typically, the DDM codes are known values ​​such that no computation is required to determine the codes—simply retrieve the DDM codes and / or the corresponding Doppler offsets associated with the codes from memory), wherein the DDM codes determine the Doppler intervals between the various transmitter TX signals utilized by the radar system. Using those DDM codes, the originally decoded range-Doppler array (e.g., determined at step 1306) is used to generate a set of offset range-Doppler arrays, wherein each new range-Doppler array is a copy of the original range-Doppler array offset in the Doppler domain by the amount determined by the DDM codes.

[0123] Therefore, at box 1310, for each DDM code in the set of DDM codes, a new range-Doppler array is created by offsetting the original range-Doppler array by the TX interval in the Doppler domain determined by the DDM code.

[0124] For example, refer to Figure 14 The example described herein illustrates that the example radar system operates using DDM codes that indicate three different TX intervals in the Doppler domain (e.g., TxDist0 representing a TX interval of 0 values ​​in the Doppler domain, TxDist1 representing a TX interval of 2 values ​​in the Doppler domain, and TxDist2 representing an interval of 5 values ​​in the Doppler domain).

[0125] Using the TX interval determined by the specified DDM code of the radar system, a set of offset range-Doppler arrays 1404 is generated according to block 1310 of method 1300. (Reference) Figure 14 The first offset distance - Doppler image 1406 is generated with an offset of 0 values, the second offset distance - Doppler image 1408 is generated with an offset of 2 values, and the third offset distance - Doppler image 1410 is generated with an offset of 5 values.

[0126] At box 1314, analyze the set of offset distance-Doppler arrays 1404 to produce the output distance-Doppler array (example provided by...). Figure 14The output range-Doppler array 1412 is depicted. In this analysis, the values ​​in the output range-Doppler array are determined by the corresponding values ​​in each of the set of offset range-Doppler arrays 1404. If all the corresponding values ​​in the set of offset range-Doppler arrays 1404 are equal to zero, this indicates no signal overlap (and in fact, no signal), so the corresponding values ​​in the output range-Doppler array are set to zero. This is depicted, for example, by the first column in the output range-Doppler array 1412. If the corresponding values ​​in the set of offset range-Doppler arrays 1404 are equal to zero except for one non-zero value, this indicates no overlap, and the corresponding value in the output range-Doppler plot is set to that non-zero value. However, if the corresponding values ​​in the set of offset range-Doppler arrays 1404 include two or more non-zero values, this indicates signal overlap, and the corresponding values ​​in the output range-Doppler array are set to zero to negate or remove the overlapping signal. This is depicted in the third column of the output range-Doppler array 1412. However, an exception may be made if two or more non-zero values ​​include values ​​significantly larger than the others. In this case, the corresponding value in the output range-Doppler array is set to the largest of the non-zero values. This is shown in the fifth column of 1412, where the non-zero value 'a' is significantly larger than the non-zero value 'c' (e.g., at least a factor of 10). In this case, the corresponding value in the output range-Doppler chart 1412 is set to the larger value 'a'. After construction, the output range-Doppler arrays are combined in each output range-Doppler array generated in box 1314 and used by the radar system to perform object DOA analysis.

[0127] At box 1318, (e.g., via a signal processor, e.g.) Figure 1 The signal processor 110 determines whether there are additional range values ​​to be processed in the input dataset at box 1304. If so, the range value is incremented at box 1320, and a one-dimensional array of analog signal values ​​extracted from the two-dimensional dataset of the current receiver and the current range value is generated. The method then returns to step 1310 to calculate a new set of offset range-Doppler arrays. However, if there are no additional range values ​​at box 1318 (indicating that all range values ​​in the current two-dimensional dataset have been processed), a determination is made at box 1324 regarding whether there are additional receiver RXs. If so, the next receiver RX is selected at box 1326, and the method returns to box 1304, where a new two-dimensional dataset is determined for the current receiver. If there are no additional receivers at box 1324, the method terminates at box 1328. The radar system can then use the corrected data generated at each iteration of box 1314 to perform DOA estimation according to the method described above.

[0128] Although examples have been described with reference to automotive radar systems, the systems and methods described herein can be implemented in conjunction with other types of radar systems.

[0129] The foregoing detailed description is illustrative in nature only and is not intended to limit the embodiments of the subject matter or the application and use of such embodiments.

[0130] As used herein, the term “exemplary” means “serving as an example, instance, or illustration.” Any embodiment described herein as exemplary should not be construed as preferred or advantageous over other embodiments. Furthermore, there is no intention to be bound by any express or implied theory presented in the foregoing technical field, background art, or specific embodiments.

[0131] The connecting lines shown in the figures contained herein are intended to represent exemplary functional relationships and / or physical connections between various elements. It should be noted that many alternative or additional functional relationships or physical connections may exist in embodiments of the subject matter. Additionally, certain terms may be used herein for reference only and are therefore not intended to be limiting, and the terms “first,” “second,” and other such numerical terms referring to structures do not imply order or sequence unless the context clearly indicates otherwise.

[0132] As used herein, a “node” means any internal or external reference point, connection point, junction, signal line, conductive element, etc., where a given signal, logic level, voltage, data mode, current, or quantity exists. Furthermore, two or more nodes can be implemented with a single physical element (and two or more signals can be multiplexed, modulated, or otherwise distinguished even if received or output at a common node).

[0133] The preceding description refers to elements, nodes, or features being “connected” or “linked” together. As used herein, unless otherwise expressly stated, “connected” means that one element is directly connected to (or directly connected to) another element, and not necessarily mechanically. Similarly, unless otherwise expressly stated, “linked” means that one element is directly or indirectly connected to (or directly or indirectly connected to, electrically or otherwise) another element, and not necessarily mechanically. Therefore, while the schematic diagrams shown depict an exemplary arrangement of elements, additional intervening elements, devices, features, or components may be present in embodiments of the depicted subject matter.

[0134] While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be understood that numerous variations exist. It should also be understood that the exemplary embodiments or embodiments described herein are not intended to limit the scope, applicability, or configuration of the claimed subject matter in any way. In fact, the foregoing detailed description will provide a convenient guide for those skilled in the art to implement the described embodiments or embodiments. It should be understood that various changes can be made to the function and arrangement of the elements without departing from the scope defined by the claims, which includes known and foreseeable equivalents at the time of filing of this patent application.

Claims

1. A radar system, characterized in that, include: Multiple transmitter modules are configured to transmit multiple transmitted radar signals according to a Doppler domain multiplexing (DDM) scheme; Multiple receiver modules are configured to receive reflections of the multiple transmitted radar signals reflected by at least one object, and to generate digital signals based on the received reflections; The signal processor is configured to: A range-Doppler antenna cube representing the digital signal is generated, the range-Doppler antenna cube comprising at least a plurality of range partitions and a plurality of Doppler partitions; For each of the plurality of range partitions of the range-Doppler antenna cube: Extract the range partition matrix from the range-Doppler antenna cube; The distance partitioning matrix is ​​used to determine a first distance partitioning array associated with the first receiver module, wherein the first distance partitioning array includes multiple values ​​associated with different Doppler partitions; An offset distance partition array is determined by offsetting a certain number of Doppler partitions as determined by the DDM scheme, the offset distance partition array including the plurality of values ​​of the first distance partition array; Determine the first Doppler partition in the first distance partition array and the offset distance partition array, each containing non-zero values; as well as The value associated with the first Doppler partition in the distance partition array is set to zero to produce a corrected distance partition array; as well as The corrected distance partition array is used to determine the estimated direction of arrival of the object.

2. The radar system according to claim 1, characterized in that, The first distance partition array is a first decoded bitmap, and the offset distance partition array is an offset version of the first decoded bitmap, wherein, in order to determine the first Doppler partitions in the first distance partition array and the offset distance partition array, each comprising non-zero values, the signal processor is further configured to: Add the first distance partition array to the offset distance partition array to produce a summed distance partition array; and The first value associated with the first Doppler partition in the summed distance partition array is determined to be equal to or greater than two.

3. The radar system according to claim 1, characterized in that, In order to set the value associated with the first Doppler partition in the range partition array to the zero value to generate a corrected range partition array, the signal processor is further configured to: A one-dimensional bitmap is defined, wherein the index of each value in the one-dimensional bitmap corresponds to a Doppler partition of the distance partition array; Set the first map value in the one-dimensional bitmap to '0', wherein the first map value has an index corresponding to the first Doppler partition; and The one-dimensional bitmap is multiplied by the distance partition array to produce the corrected distance partition array.

4. A radar system, characterized in that, include: Multiple receiver modules are configured to receive reflections of multiple transmitted radar signals; as well as The signal processor is configured to: Extract the range partition matrix from the range-Doppler antenna cubes generated by the reflections of the plurality of transmitted radar signals. A first distance partitioning array is determined, the first distance partitioning array comprising multiple values ​​associated with different Doppler partitions. An offset distance partition array is determined, offset by a certain number of Doppler partitions, wherein the offset distance partition array includes the plurality of values ​​of the first distance partition array. Determine the first Doppler partition in the first distance partition array and the offset distance partition array, each comprising a non-zero value, and The value associated with the first Doppler partition in the first distance partition array is set to zero to produce a corrected distance partition array; as well as The corrected distance partition array is used to determine the estimated direction of arrival of the object.

5. The radar system according to claim 4, characterized in that, The first distance partition array is a first decoded bitmap, and the offset distance partition array is an offset version of the first decoded bitmap.

6. The radar system according to claim 5, characterized in that, To determine the first Doppler partition in the first distance partition array and the offset distance partition array, each comprising non-zero values, the signal processor is further configured to: Add the first distance partition array to the offset distance partition array to produce a summed distance partition array; and The first value associated with the first Doppler partition in the summed distance partition array is determined to be equal to or greater than two.

7. The radar system according to claim 4, characterized in that, In order to set the value associated with the first Doppler partition in the range partition array to the zero value to generate a corrected range partition array, the signal processor is further configured to: A one-dimensional bitmap is defined, wherein the index of each value in the one-dimensional bitmap corresponds to a Doppler partition of the distance partition array; Set the first map value in the one-dimensional bitmap to '0', wherein the first map value has an index corresponding to the first Doppler partition; and The one-dimensional bitmap is multiplied by the distance partition array to produce the corrected distance partition array.

8. A method, characterized in that, include: The receiver system is used to receive reflections of multiple transmitted radar signals; Extract the range partition matrix from the range-Doppler antenna cubes generated by the reflections of the plurality of transmitted radar signals; A first distance partition array is determined, the first distance partition array including multiple values ​​associated with different Doppler partitions; An offset distance partition array is determined by offsetting a certain number of Doppler partitions, the offset distance partition array including the plurality of values ​​of the first distance partition array; Determine the first Doppler partition in the first distance partition array and the offset distance partition array, each containing non-zero values; The value associated with the first Doppler partition in the first distance partition array is set to zero to produce a corrected distance partition array; as well as The corrected distance partition array is used to determine the estimated direction of arrival of the object.

9. The method according to claim 8, characterized in that, Additionally, it includes transmitting the plurality of transmitted radar signals according to a Doppler Domain Multiplexing (DDM) scheme, wherein the number of Doppler partitions is determined by the DDM scheme.

10. The method according to claim 9, characterized in that, The first distance partition array is a first decoded bitmap, and the offset distance partition array is an offset version of the first decoded bitmap. The method further includes determining first Doppler partitions in the first distance partition array and the offset distance partition array, each comprising non-zero values: Add the first distance partition array to the offset distance partition array to produce a summed distance partition array; as well as The first value associated with the first Doppler partition in the summed distance partition array is determined to be equal to or greater than two.

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