Hybrid random time division multiplexing (RTDM) Doppler division multiplexing (DDM) multiple-input multiple-output (MIMO) radar system and method

Abstract

A radar system and a method of operating a radar system are provided. The radar system includes: transmitter groups, each including transmitter modules, the transmitter groups configured to transmit a plurality of transmit signals according to a random time division multiplexing (RTDM)-Doppler domain multiplexing (DDM) scheme; a receiver module configured to receive a reflection of the transmit signal reflected by at least one object and to generate a digital signal based on the received reflection; and a controller comprising a signal processor configured to: generate a plurality of range-Doppler antenna cubes (RDACs) based on the reflections of the plurality of transmit signals, each RDAC of the plurality of RDACs corresponding to a respective one of the groups of transmitters; generating a combined distance-Doppler map (RDM) by integrating the plurality of RDACs; and generating object position data based on the combined RDM.

Description

Technical Field

[0001] Embodiments of the subject matter described herein generally relate to radar systems, including multiple-input multiple-output (MIMO) radar systems and associated methods. Background Art

[0002] Radar systems can be used to detect the distance, speed, and angle of nearby objects. With advances in technology, radar systems can now be applied to many different applications, such as automotive radar safety systems, which increasingly use radar systems to detect changes in the surrounding environment, such as the proximity of another car for blind spot detection, or to detect vehicles ahead to improve cruise control. Accurate radar detection is also an integral part of autonomous vehicle control systems. However, there are challenges in accurately detecting the position and movement of objects using radar systems that can be built on cars. A common approach to improving the angular resolution of automotive radar systems is to implement a multiple-input multiple-output (MIMO) automotive radar system using multiple transmit and receive antennas. In a MIMO radar system, a virtual array is formed by a number of array elements equal to the product of the number of transmit antennas and the number of receive antennas. Compared to a single transmitter system, the increased aperture of a MIMO radar improves the ability to distinguish between objects based on the angle of arrival (AoA) of the signal reflected by the object. Summary of the invention

[0003] In the example embodiments, a brief overview of various exemplary embodiments is presented below. Some simplifications and omissions may be made in the following overview, which is intended to highlight and introduce some aspects of the various exemplary embodiments, rather than to limit the scope. In later sections, a detailed description of the exemplary embodiments sufficient to allow a person of ordinary skill in the art to obtain and use these concepts will be given.

[0004] In an example embodiment, a radar system includes: a plurality of transmitter groups, each transmitter group including a plurality of transmitter modules, the plurality of transmitter groups being configured to transmit a plurality of transmission signals according to a random time division multiplexing (RTDM)-Doppler domain multiplexing (DDM) scheme; a plurality of receiver modules configured to receive reflections of the plurality of transmission signals reflected by at least one object and generate digital signals based on the received reflections; and a controller. The controller includes a signal processor configured to: generate a plurality of range-Doppler antenna cubes (RDACs) based on the reflections of the plurality of transmission signals, each of the plurality of RDACs corresponding to a respective transmitter group in the plurality of transmitter groups; generate a combined range-Doppler map (RDM) by integrating the plurality of RDACs; and generate object position data based on the combined RDM.

[0005] In one or more embodiments, the signal processor for generating the plurality of RDACs is further configured to: generate a first RDAC by performing range compression and Doppler compression on raw analog-to-digital converter (ADC) data representing a first reflection associated with a first transmit signal of a first transmitter group among the plurality of transmitter groups; and generate a second RDAC by performing range compression and Doppler compression on raw ADC data representing a second reflection associated with a second transmit signal of a second transmitter group among the plurality of transmitter groups.

[0006] In one or more embodiments, the signal processor for generating the combined RDM by integrating the plurality of RDACs is further configured to generate the combined RDM by incoherently integrating the plurality of RDACs.

[0007] In one or more embodiments, the controller is configured to, for each transmission period in a given radar transmission frame, randomly select only one of the plurality of transmitter groups to transmit during the transmission period.

[0008] In one or more embodiments, the controller is further configured to select each of the multiple transmitter groups to transmit in a total of K / m transmission time periods in the radar transmission frame, where K is the total number of transmission time periods in the radar transmission frame and m is the total number of transmitter groups in the multiple transmitter groups.

[0009] In one or more embodiments, the controller is further configured to: randomly select a first transmitter group from the plurality of transmitter groups to transmit during a first transmission period of the radar transmission frame; and randomly select a second transmitter group from the plurality of transmitter groups to transmit during a second transmission period of the radar transmission frame. The second transmitter group is inactive during the first transmission period, and the first transmitter group is inactive during the second transmission period.

[0010] In one or more embodiments, each of the transmitter modules of the plurality of transmitter groups comprises a phase rotator configured to apply a phase shift to a transmit signal generated by the transmitter module based on a predefined DDM code.

[0011] In one or more embodiments, the predefined DDM code causes the phase rotator to apply the phase shift progressively according to a Co-Prime Coding (CPC) coding technique.

[0012] In one or more embodiments, for a given transmitter module among the multiple transmitter modules, the phase rotator of the given transmitter module is configured to apply the phase shift to the given transmit signal based on an index of the given transmitter module relative to a transmitter group among the multiple transmitter groups and a transmission period of a radar transmission frame in which the given transmit signal is to be transmitted.

[0013] In one or more embodiments, the signal processor is further configured to reduce the sidelobe amplitude of the combined RDM using coherent cancellation.

[0014] In an example embodiment, a method includes: transmitting a plurality of transmission signals by a plurality of transmitter groups of a radar system according to a random time division multiplexing (RTDM)-Doppler domain multiplexing (DDM) scheme, each of the plurality of transmitter groups including a plurality of transmitter modules; receiving, by a plurality of receiver modules of the radar system, reflections of the plurality of transmission signals reflected by at least one object; generating, by the plurality of receiver modules, digital signals based on the received reflections; and generating, by a signal processor of a controller of the radar system, a plurality of range-Doppler antenna cubes (RDACs) based on the reflections of the plurality of transmission signals, each of the plurality of RDACs corresponding to a respective transmitter group of the plurality of transmitter groups; generating, by the signal processor, a combined RDM by integrating the plurality of RDACs; and generating, by the signal processor, object position data based on the combined RDM.

[0015] In one or more embodiments, generating the plurality of RDACs further includes: generating, by the signal processor, a first RDAC by performing range compression and Doppler compression on raw analog-to-digital converter (ADC) data representing a first reflection associated with a first transmit signal of a first transmitter group among the plurality of transmitter groups; and generating, by the signal processor, a second RDAC by performing range compression and Doppler compression on raw ADC data representing a second reflection associated with a second transmit signal of a second transmitter group among the plurality of transmitter groups.

[0016] In one or more embodiments, generating the combined RDM by integrating the plurality of RDACs further comprises generating, by the signal processor, the combined RDM by incoherently integrating the plurality of RDACs.

[0017] In one or more embodiments, the method further includes for each transmission period in a given radar transmission frame, randomly selecting, by the controller, only one of the plurality of transmitter groups to transmit during the transmission period.

[0018] In one or more embodiments, the method further includes selecting, by the controller, each of the multiple transmitter groups to transmit in a total of K / m transmission time periods in the radar transmission frame, where K is the total number of transmission time periods in the radar transmission frame and m is the total number of transmitter groups in the multiple transmitter groups.

[0019] In one or more embodiments, the method further includes: randomly selecting, by the controller, a first transmitter group from among the multiple transmitter groups for transmission in a first transmission period of the radar transmission frame; and randomly selecting, by the controller, a second transmitter group from among the multiple transmitter groups for transmission in a second transmission period of the radar transmission frame; configuring, by the controller, the second transmitter group to be inactive during the first transmission period; and configuring, by the controller, the first transmitter group to be inactive during the second transmission period.

[0020] In one or more embodiments, the method further includes applying, by a phase rotator of a transmitter module of the plurality of transmitter modules, a phase shift based on a predefined DDM code to a transmit signal generated by the transmitter module.

[0021] In one or more embodiments, applying the phase shift to the transmit signal includes applying the phase shift by the phase rotator progressively according to a co-prime coding (CPC) coding technique.

[0022] In one or more embodiments, applying the phase shift to the transmit signal includes applying, by the phase rotator, a first phase shift to the first transmit signal based on an index of the transmitter module relative to a corresponding transmitter group among the plurality of transmitter groups and a transmission period of a radar transmission frame in which the first transmit signal is to be transmitted.

[0023] In one or more embodiments, the method further comprises performing, by the signal processor, coherent cancellation to reduce a sidelobe amplitude of the combined RDM. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] A more complete understanding of the subject matter may be obtained by referring to the detailed description and claims considered in conjunction with the following drawings, in which like reference numerals refer to similar elements in the various figures. The elements in the figures are shown for simplicity and clarity and are not necessarily drawn to scale. The accompanying drawings, together with the detailed description, are incorporated into and form part of this specification, and are used to further illustrate examples, embodiments, etc., and to explain various principles and advantages according to the present disclosure. In the drawings:

[0025] Figure 1 is a block diagram illustrating an example radar system according to one or more embodiments;

[0026] Figure 2 is a timing diagram showing a linear chirp transmission schedule for a Doppler division multiplexing (DDM) multiple-input multiple-output (MIMO) radar system;

[0027] Figure 3 is a diagram illustrating transmitter phase offsets of two transmitter (TX) groups in a sequence of transmission periods according to a random time domain multiplexing (RTDM)-DDM MIMO transmission schedule in accordance with one or more embodiments;

[0028] Figure 4 is a diagram showing an example according to one or more embodiments. Figure 3 A timing diagram of a linear chirp transmission schedule for a first TX group of an RTDM-DDM MIMO transmission schedule and other three transmitters of the first TX group;

[0029] Figure 5 is a diagram showing an example according to one or more embodiments. Figure 3 A timing diagram of a linear chirp transmission schedule for three transmitters of a second TX group of the RTDM-DDM MIMO transmission schedule; and

[0030] Figure 6 is a process flow diagram describing an object tracking method in combination with a hybrid RTDM-DDM MIMO method according to one or more embodiments, wherein the method may be performed by, for example Figure 1 The radar system and other radar systems are executed. DETAILED DESCRIPTION

[0031] The following detailed description is merely illustrative in nature and is not intended to limit the embodiments of the subject matter or the application and uses of such embodiments. In addition, it is not intended to be bound by any explicit or implicit theory presented in the foregoing technical field, background technology or the following detailed description.

[0032] For simplicity and clarity of illustration, the drawings show a general construction approach, and descriptions and details of well-known features and techniques may be omitted for brevity. In addition, the elements in the drawings are not necessarily drawn to scale. For example, the dimensions of some elements or regions in the drawings may be exaggerated relative to other elements or regions to help improve the understanding of the embodiments described herein.

[0033] The terms "first", "second", "third", "fourth", etc. (if any) in the description and claims may be used to distinguish similar elements and are not necessarily used to describe a specific sequential order or time order. It should be understood that the terms used in this way are interchangeable where appropriate, so that the embodiments described herein can, for example, operate in a sequence different from that shown or described herein. In addition, the terms "including", "having" and any variations thereof are intended to cover non-exclusive inclusions, so that processes, methods, articles or devices including a series of elements are not necessarily limited to those elements, but may include other elements that are not explicitly listed or inherent to such processes, methods, articles or devices. The term "coupled" used herein is defined as being connected directly or indirectly in an electrical or non-electrical manner. As used herein, the terms "substantially" and "substantially" mean sufficient to achieve the stated purpose in a practical manner, and minor defects (if any) are not important for the stated purpose. As used herein, the words "exemplary" or "example" mean "serving as an example, instance or illustration". Any embodiment described herein as exemplary or exemplary should not necessarily be understood as being preferred or advantageous over other embodiments.

[0034] Unless otherwise stated, directional references such as "top", "bottom", "left", "right", "above", "below", etc. are not intended to require any preferred orientation, but are described for illustrative purposes with reference to the orientation of the corresponding figure or figures.

[0035] For the sake of brevity, conventional semiconductor manufacturing techniques may not be described in detail herein. In addition, certain terms may also be used herein for reference only and are therefore not intended to be limiting. For example, the terms "first," "second," and other such numerical terms referring to structures do not imply a sequence or order unless clearly indicated by the context.

[0036] Various embodiments described herein relate to a hybrid random time division multiplexing (RTDM) Doppler division multiplexing (DDM) multiple input multiple output (MIMO) radar system with integrated object tracking capability. Conventional DDM MIMO radar systems operate using fully simultaneous transmissions of all transmitters / transmit (TX) channels. However, due to peak power limitations, power consumption constraints, thermal management issues, and / or excessive overlap of Doppler spectra that may occur in DDM radar systems, various applications of such radar systems may not allow such operations. In contrast, conventional time division multiplexing (TDM) radar systems can achieve peak power, power consumption, and heat reduction compared to conventional DDM radar systems, but at the expense of aliased and / or ambiguous velocity measurements, which typically require correction by phase compensation before angle estimation. Compared to conventional DDM radar systems, embodiments of the hybrid RTDM-DDM MIMO radar system described herein can advantageously present lower peak power, power consumption, and heat generation, while mitigating velocity measurement aliasing and ambiguity (associated with conventional TDM radar systems), so that the need for phase compensation before angle estimation can be advantageously avoided. Additionally, embodiments of the hybrid RTDM-DDM MIMO radar system may advantageously reduce Doppler domain spectrum overlap compared to conventional DDM radar systems. Additionally, embodiments of the hybrid RTDM-DDM MIMO radar system may advantageously have increased gain compared to conventional DDM radar systems.

[0037] In one or more embodiments, a radar system includes a microcontroller unit (MCU) having a signal processor configured to generate a range-Doppler antenna cube (RDAC) from, for example, raw ADC samples derived from a return signal (i.e., reflection) corresponding to reflections of a transmitted signal (e.g., chirp) transmitted through a transmitter (TX) antenna element using a transmitter module of the radar system (e.g., according to a hybrid RTDM-DDM scheme, as a non-limiting example, the hybrid RTDM-DDM scheme having a uniform pulse repetition interval (PRI) or a mutually prime coded (CPC) PRI). The return signal is received by a receiver (RX) antenna element of the radar system.

[0038] For example, when implementing a hybrid RTDM-DDM scheme, the radar system may assign available transmitters into two or more groups (sometimes referred to herein as "TX groups", "TX antenna groups", or "TX channel groups"), and may randomly or pseudo-randomly select which TX group to use for radar signal transmission in a given transmission period. Each transmission period corresponds to a PRI, and each transmitter module of the selected TX group is configured to transmit a single radar signal (e.g., a single chirp) during a given transmission period. In one or more embodiments, only one TX group is selected for transmission in any given transmission period. The radar system may transmit radar signals according to a DDM scheme in which each transmitter of a given TX group has a respectively different self-induced chirp-to-chirp phase rotation while substantially maintaining a common and constant pulse repetition frequency (PRF), except during transmission periods in which a given TX group is not selected for transmission. This causes each transmitter module of the selected group to transmit a sequence of signals that are orthogonal in the Doppler domain, so that the return signal received from each object in the environment of the radar system is replicated in the Doppler domain at different speeds, depending on the transmitter associated with the return signal. These replications depend on the DDM code used to define the corresponding phase rotation of each TX channel, and the order of the replications needs to be known in order to correctly construct the MIMO array. Finding the order of such replicas is referred to herein as "decoding" or "DDM decoding", which is equivalent to Find the unambiguous speed of the target within the unambiguous Doppler range, where T R is the pulse repetition interval (PRI). In one or more embodiments, the same DDM scheme may be used for all transmitters of the radar system, regardless of the TX group, and the phase rotation applied to a given TX channel based on the DDM code may depend on the current transmission period and the index of the given TX channel within the TX group of the given TX channel.

[0039] For each TX group, one or more ADCs of the receiver module of the radar system may generate a corresponding set of raw ADC data representing the radar signal transmitted by the TX group. The signal processor of the radar system may process each set of raw ADC data separately to generate an RDAC, each RDAC corresponding to the corresponding TX group. For example, the RDAC associated with a given TX group of the radar system may 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 the raw ADC samples representing the reflection of the chirp transmitted simultaneously via the associated TX group. The signal processor of the radar system may then perform incoherent integration of the RDAC to generate a combined RDAC. The radar system may then use the combined RDAC to perform constant false alarm rate (CFAR) peak detection, DDM decoding, MIMO array construction, generation of object position data, and / or generation of object tracking data.

[0040] Figure 1 A block diagram of a hybrid RTDM-DDM MIMO automotive radar system 100 is shown, including a hybrid RTDM-DDM MIMO radar device 102 connected to a radar microcontroller unit (MCU) 104. In one or more embodiments, the device 102 may be a linear frequency modulation (LFM) RTDM-DDM MIMO radar device. In one or more embodiments, the hybrid RTDM-DDM MIMO radar device 102 may be embodied as a field replaceable unit (LRU) or a modular component designed to be quickly replaced in an operating position. Similarly, the radar MCU 104 may be embodied as a field replaceable unit (LRU) or a modular component. Although a single or single-base hybrid RTDM-DDM MIMO radar device 102 is shown, it should be understood that additional distributed radar devices may be used to form a distributed or multi-base radar. In addition, the depicted radar system 100 may be implemented in the form of an integrated circuit, wherein the hybrid RTDM-DDM MIMO radar device 102 and the radar MCU 104 are formed with separate integrated circuits (chips) or a single chip, depending on the application.

[0041] 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 connected to a plurality of antenna elements 126, 128 ... M TX1, TX2, TX3, ...TX M1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, N , where "N" is the total number of receivers. In this document, RX1, RX2, RX3, ... RX N 118) and sixteen receiver modules (e.g., receiver modules 128). These numbers of transmitter and receiver antenna elements and modules are intended to be illustrative and non-limiting, wherein other numbers 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 chirp input signal to transmitter module 118. To this end, chirp generator 116 is configured to receive input program and control signals from MCU 104, which, as non-limiting examples, 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 the chirp signal to the transmitter module 118 for transmission through the transmit antenna element 126. The transmitted chirp signal is sometimes referred to herein as a "transmit signal."

[0042] In one or more embodiments, each transmitter module 118 includes a phase rotator 120 (sometimes referred to herein as a "phase shifter 120") configured to apply a phase encoding (e.g., based on a DDM code) to a chirp signal, wherein the phase rotator 120 is controlled by a program control signal generated by the MCU 104 (e.g., by the radar controller 108 of the MCU 104). The transmitter modules 118 (and, in one or more embodiments, the associated TX channels and TX antennas) may be organized into different TX groups. The radar system 100 may randomly or pseudo-randomly select one such TX group to transmit during each transmission period, while the remaining unselected TX groups are configured (e.g., by the MCU 104) to be inactive or deactivated. In one or more embodiments, the phase rotator 120 may provide a uniform phase shift between the transmitter modules 118 of a given TX group. According to one or more other embodiments, alternatively, the phase rotator 120 may provide each transmitter module 118 with the ability to implement a progressive phase shift using a non-uniform coding technique such as a coprime coding (CPC) coding technique. Each transmitter module 118 includes an RF conditioning module 122 configured to filter the phase-coded chirp signal. Each transmitter module 118 includes a power amplifier 124 configured to amplify the filtered phase-coded chirp signal before it is provided to and transmitted via one or more corresponding transmit antenna elements 126.

[0043] By transmitting a sequence of progressively phase-shifted chirp signals using each transmit antenna 126, the transmit module 118 transmits a sequence of progressively phase-shifted chirp signals using the associated transmit antenna when selected for transmission in a given transmission period, thereby operating in a Doppler division multiplexing manner with other transmitter modules in the transmitter modules 118, wherein the transmitter modules 118 in the same TX group can be programmed to transmit the same waveform (e.g., chirp) simultaneously in a phase-separated schedule. By randomly or pseudo-randomly selecting individual TX groups in the TX group to transmit during different transmission periods, the radar system 102 causes the transmit modules 118 to additionally operate in a hybrid random time domain multiplexing-Doppler division multiplexing manner, at least when such TX group selection is performed randomly or pseudo-randomly, and when a phase offset is applied by the phase rotator 120 of each transmit module 118 according to a DDM code.

[0044] The radar signal transmitted by the transmitter antenna module 118 may be reflected by objects in the environment of the radar device 102, and a portion of the reflected radar signal, sometimes referred to herein as a "return signal" or "reflection", is received by the receiver antenna module 128 at the radar device 102. At each receiver module 128, the received (RF) antenna signal is amplified by a low noise amplifier (LNA) 140 and then fed to a mixer 138, where the received (RF) antenna signal is mixed with the transmitted chirp signal generated by the RF conditioning module 122. The resulting intermediate frequency signal is fed to a high pass filter (HPF) 136. The resulting filtered signal is fed to a variable gain amplifier 134, which amplifies the filtered signal before feeding it to a low pass filter (LPF) 132. This re-filtered signal is fed to an analog-to-digital converter (ADC) 130 and output by each receiver module 128 as a digital signal (e.g., to the signal processor 110 of the MCU 104). In this manner, the receiver module 128 compresses the various delayed target echoes into a plurality of sinusoidal tones whose frequencies correspond to the round-trip delays of the echoes.

[0045] In the radar system 100, the radar MCU 104 may be connected and configured to supply input control signals to the radar device 102 and receive digital output signals generated by the receiver module 128 therefrom. In one or more embodiments, the radar MCU 104 includes a radar controller 108 and a signal processor 110, wherein either or both of the radar controller 108 and the signal processor 110 may be embodied as a microcontroller unit (MCU) or other processing unit. The radar controller 108 may receive data from the radar device 102 (e.g., from the receiver module 128) and may control radar parameters of the radar device 102, such as the frequency band, length, etc. of each radar frame. The signal processor 110 may be configured and arranged for signal processing tasks, such as, but not limited to, target object identification, calculating the spacing or distance to the target object, calculating the radial velocity of the target object, and calculating the AoA of the signal reflected by the target object. In this document, the term "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 .

[0046] As non-limiting examples, the interface 106 may enable the MCU 104 to communicate with other systems via local and wide area networks, the Internet, a car communication bus, and / or other types of wired or wireless communication systems. In one or more embodiments, the MCU 104 may provide calculated values ​​to other systems, such as a radar-camera-lidar fusion system; an automated driving assistance system including parking, braking, or lane change assistance features; and the like, via the interface 106. The storage device 112 may be used to store instructions for the MCU 104, data received from the radar device 102, calculated values ​​from the signal processor 110, and the like. The storage device 112 may be any suitable storage medium, such as a volatile or non-volatile memory.

[0047] To control the transmitter module 118, the radar controller 108 may, for example, be configured to generate transmitter input signals, such as programs, control triggers, reference LO signals, calibration signals, and / or spectrum shaping signals (e.g., ramp generation in the case of an FMCW radar). The radar controller may, for example, be configured to receive data signals, sensor signals, and / or register programming or state machine signals for an RF (radio frequency) circuit enable sequence. In one or more embodiments, the radar controller 108 may be configured to program the transmitter module 118 with the transmitter input signals to operate in a DDM manner by progressively shifting the phase of the LFM chirp to be transmitted by the transmit antenna element 126 (when selected for transmission according to the RTDM scheme).

[0048] In selected embodiments, the radar controller 108 is configured to progressively phase shift the LFM chirp output by the chirp generator 116 with co-prime coding (CPC) coding by programming the programmable phase rotator 120 prior to transmission. In one or more such embodiments, each transmitter module 118 transmits a transmit channel signal having a different CPC-coded LFM signal generated using the programmable slow-time phase rotator 120 so that the receiver module 128 can adjust the target object return signal (i.e., a return signal corresponding to a reflection of the transmit signal transmitted by the transmit antenna element 126 from one or more target objects, wherein the return signal is then received by the receive antenna element 142) to produce a digital domain signal that is processed by the radar MCU 104 to separate and identify the CPC-coded transmit channel signal. In one or more such embodiments, the CPC coding applied to the LFM signal of a given transmitter module 118 by the phase rotator 120 of the given transmitter module 118 may depend on the index of the transmitter module 118 in its TX group, as described in more detail below (e.g., in Figure 3 ).

[0049] 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 the MIMO array vector output to form a MIMO aperture for calculating the plot or map of the AoA estimate and the target object trajectory. Specifically, in the signal processor 110, the digital output signal may be processed by one or more fast Fourier transform (FFT) modules or discrete Fourier transform (DFT) modules, such as a fast time (range) FFT module that generates a range chirp antenna cube (RCAC) and a slow time (Doppler) FFT module that generates a range-Doppler antenna cube (RDAC). In one or more embodiments, the signal processor 110 may be configured to separately process the raw ADC samples representing the reflections of the transmit signal generated by each TX group, so that the signal processor 110 generates a separate RDAC for each TX group. The signal processor 110 then combines these TX group-specific RDACs using non-coherent integration (NCI) to generate a combined range-Doppler map (RDM). Herein, "RDM" refers to a matrix or two-dimensional array of range-Doppler cells. The signal processor 110 may further process the combined RDM by performing peak detection (e.g., using constant false alarm rate (CFAR) detection) to identify amplitude peaks in the combined RDM (in the Doppler spectrum) and applying DDM decoding techniques to associate the identified peaks with corresponding transmitters and / or TX channels, thereby removing the ambiguity of the DDM MIMO waveform represented in the combined RDM and generating TX-associated peaks (in the Doppler spectrum). The signal processor 110 may additionally process the TX-associated peaks to construct a DDM MIMO array vector, which the signal processor 110 may then process to perform AoA estimation and target object tracking. The MCU 104 may then output the resulting target trajectory (e.g., via the interface 106) to other automotive computing devices or user interface devices for further processing or display.

[0050] For contextual understanding of the operation of a DDM MIMO radar system utilizing CPC coding, reference is now made to Figure 2 , which shows a timing diagram 200 illustrating a linear chirp transmission schedule 201, 202, and 203 for three transmitters using a non-uniform Doppler segmentation scheme that employs co-prime coding (CPC). In the current example where RTDM is not used, each transmitter TX1-TX3 is programmed to simultaneously transmit a sequence of DDM linear chirp waveforms in a single radar transmission frame. Each transmitter transmits a linear chirp waveform (e.g., 201A, 201B) at a fixed and uniform pulse repetition frequency (PRF) rate, which is the inverse of the pulse repetition interval (e.g., PRF=PRF). -1) or the inverse of the chirp interval (e.g., PRF = CIT -1 ). In this article, each PRI within a given radar transmission frame may be referred to as a "transmission period". Each of the transmitters TX1-TX3 is configured to transmit one chirp per transmission period. In addition, each transmitter encodes each chirp with an additional progressive phase offset using a phase rotator in the front-end circuit. By using progressive phase offset CPC coding, the Doppler spectra of transmitters TX1-TX3 are effectively allocated according to the principle of coprime number theory, so that in a single transmission frame, when the spectra of each transmitter overlap each other severely, the Doppler spectrum signals of different transmitters can be separated. By encoding the DDM MIMO waveform using coprime-based zero radial velocity frequency intervals, the Doppler spectrum detection of each transmitter can be robustly and unambiguously reconstructed to be associated with the correct transmitter, thereby enabling more transmitters to share the limited Doppler spectrum limited by the maximum achievable PRF. Therefore, each received chirp originating from each different transmitter TX1-TX3 effectively has a different zero radial velocity Doppler shift, and each target detection can be associated with the correct starting transmitter, which is necessary for the subsequent MIMO virtual array construction to function correctly.

[0051] exist Figure 2 In the example of FIG. 1 , a differentiated CPC encoding scheme is depicted, wherein a first transmitter TX1 encodes its chirped waveform 201 with a progressive phase offset of 0 degrees, a second transmitter TX2 encodes its chirped waveform 202 with a progressive phase offset of 17 / 64×PRF=95.625 degrees, and a third transmitter TX3 encodes its chirped waveform 203 with a progressive phase offset of 43 / 64×PRF=241.875 degrees. Thus, for zero radial velocity detection from the first transmitter TX1, the first transmitter TX1 has an allocated spectrum segment centered at 0×PRF=0 degrees. Additionally, for zero radial velocity detection from the second transmitter TX2, the second transmitter TX2 has an allocated spectrum segment centered at 17 / 64×PRF=95.625 degrees. Finally, for zero radial velocity detections from the third transmitter TX3, the third transmitter TX3 has an allocated spectral segment centered at 43 / 64×PRF=241.875 degrees. By encoding each DDM transmitter TX1-TX3 using coprime-based zero radial velocity frequency spacings, the received Doppler-sliced ​​MIMO waveform can be processed using CPC decoding to correctly associate each transmitter Doppler spectrum detection with the correct transmitter. The arrangement of zero radial velocities that produces spacing values ​​{17, 26, 21} are coprime numbers in units of PRF / 64 [Hz].

[0052] Figure 3A diagram 300 is shown showing phase offsets of a first TX group 302 and a second TX group 304 in a radar transmission frame including K transmission periods according to a hybrid RTDM-DDM MIMO transmission schedule. Figure 1 The radar system 102 depicts Figure 3 However, it should be understood that this is intended to be illustrative rather than limiting, and in one or more other embodiments, the timing schedule shown in diagram 300 may be used to control transmitters in other suitable radar systems.

[0053] Although the present example illustrates a hybrid RTDM-DDM MIMO scheme using two TX groups, it should be understood that this is intended to be illustrative and not limiting. For example, in one or more other embodiments, other suitable numbers of TX groups, such as three, four, or more TX groups, may be used for the RTDM-DDM MIMO scheme, where the radar system is configured to randomly or pseudo-randomly select one of the available groups to transmit during a given transmission period of a radar transmission frame.

[0054] The first TX group 302 includes transmitters TX1-TX6, and the second TX group 304 includes transmitters TX7-TX 12 , where each transmitter may be associated with a corresponding set of TX modules 118 and TX antennas 126. The MCU 104 may configure each transmitter with a corresponding phase offset based on a predefined DDM code (e.g., by controlling the phase rotator 120). For example, the phase offset of each chirp transmission in each transmission period is defined by the following equation:

[0055]

[0056]

[0057] where i represents the index of the transmitter to which the phase offset is to be applied relative to the TX group of the transmitter, k represents the transmission period (in the present example, in the range of 0 to K-1, where K is the total number of transmission periods in the radar transmission frame), P represents the number of bits of the phase rotator (e.g., phase rotator 120) that applies the phase offset, and code i represents the DDM code to be applied for index i.

[0058] As shown in this example, time domain multiplexing is applied between the TX groups such that only one of the TX groups 302, 304 is selected by the MCU 104 for transmission in any given transmission period. In one or more embodiments, the transmitters of the selected TX group may each transmit a single LFM chirp in a given transmission period. For example, according to various embodiments, during a first transmission period 306, the MCU 104 may select the first TX group 302 for transmission while the second TX group 304 is configured to be inactive or deactivated (e.g., configured by the MCU 104). Continuing with this example, according to various embodiments, during a second transmission period 308, the MCU 104 may select the second TX group 304 for transmission while the first TX group 302 is configured to be inactive or deactivated (e.g., configured by the MCU 104).

[0059] Compared to the conventional TDM method of setting a predefined periodic transmission schedule for each transmitter, the MCU 104 can randomly or pseudo-randomly determine which group of the TX groups 302, 304 is selected for transmission during each transmission period. For example, given a radar transmission frame including K consecutive transmission periods, the transmitters of the radar system 100 are divided into m TX groups (wherein in this example, m=2). Each TX group may include M / m transmitters, where M is the total number of transmitters included in the radar system 100. Although in this example, the TX groups 302, 304 are shown as including consecutive transmitter groups, it should be understood that this is intended to be illustrative and not limiting. For example, in one or more other embodiments, any other suitable transmitter grouping may be used when defining the TX group, so that a given TX group does not necessarily include a spatially consecutive transmitter group.

[0060] Each TX group may be configured to transmit during a total of (K / m) transmission time periods (non-overlapping) of a radar transmission frame according to a hybrid RTDM-DDM scheme. In one or more embodiments, when implementing the hybrid RTDM-DDM scheme, the MCU 104 of the radar system 100 may randomly select the order in which the TX groups are selected for transmission in the K transmission time periods of the frame, while ensuring that each TX group is selected for transmission in a total of K / m transmission time periods. That is, each TX group is configured to transmit K / m chirps in a given radar transmission frame. For example, given m=2 and K=1024 transmission time periods in a radar transmission frame, the first TX group 302 may be transmitted in 512 transmission time periods, and the second TX group 304 may be transmitted in 512 transmission time periods, and the transmission order may be randomly determined by the MCU 104.

[0061] In one or more other embodiments, the MCU 104 may pseudo-randomly select the order in which the TX groups are selected for transmission in the K consecutive transmission time periods of the radar transmission frame. As a non-limiting example, the MCU 104 may divide the K consecutive transmission time periods into a certain number (K / m) of consecutive transmission time period groups, where each transmission time period group includes m consecutive transmission time periods. Continuing with this example, the MCU 104 may select each TX group to transmit exactly once in each transmission time period group in a random order. Such a configuration may cause each TX group to be selected for transmission in no more than two consecutive transmission time periods of the radar transmission frame.

[0062] The embodiment of the hybrid RTDM-DDM MIMO method of this example does not require all transmitters of the radar system 100 to transmit simultaneously, and can advantageously exhibit lower peak power, power consumption, and heat generation than conventional DDM radar systems, while mitigating velocity measurement aliasing and ambiguity (associated with conventional TDM radar systems) that would otherwise require phase compensation prior to angle estimation. In addition, compared to conventional DDM radar systems, embodiments of the hybrid RTDM-DDM MIMO method of the present invention can advantageously reduce Doppler domain spectral overlap, particularly when the total number of transmitters in the radar system is large. In addition, compared to conventional DDM radar systems, embodiments of the hybrid RTDM-DDM MIMO method of the present invention can have advantageously increased gain.

[0063] It should be noted that one or more embodiments of the hybrid RTDM-DDM MIMO method of the present invention may produce relatively high Doppler sidelobes in the combined RDM. As a non-limiting example, optimized downsampling, coherent cancellation and / or other suitable techniques may be used to mitigate or correct the increase in the amplitude of such Doppler sidelobes. In one or more embodiments, such mitigation or correction techniques may be applied before decoding the combined RDM. As a non-limiting example, the signal processor 110 may be configured to reduce the Doppler sidelobe amplitude by reconstructing a slow-time signal corresponding to a strong visible target (i.e., a Doppler spectrum peak in the RDM that exceeds a predetermined threshold amplitude), and then subtracting this reconstruction from the combined RDM to reveal a weaker target (i.e., a Doppler spectrum peak with a relatively low amplitude). According to one or more embodiments, this process may be repeated until the desired dynamic range is reached.

[0064] According to the hybrid RTDM-DDM MIMO scheme, Figure 4 and 5 An example timing diagram is shown in , respectively, showing a linear chirp transmission schedule for a subset of transmitters of the first TX group 302 and the second TX group 304. Figure 1 The radar system 100 and Figure 3 FIG300 together describes Figure 4and 5 For comparison purposes, the DDM scheme used when applying phase offsets to the transmitters of the first and second TX groups is similar to Figure 2 The DDM scheme used in the example, and for the sake of brevity, some details of the DDM scheme that have been described are not repeated here.

[0065] Figure 4 A timing diagram 400 is shown showing a linear chirp transmission schedule 401 , 402 , 403 of transmitters TX1 , TX2 and TX3 of a first TX group 302 . Figure 5 A timing diagram 500 is shown showing linear chirp transmission schedules 501, 502, 503 for transmitters TX7, TX8, and TX9 of the second TX group 304. It should be noted that the same time scale is used to show each of the linear chirp transmission schedules 401, 402, 403, 501, 502, 503. Figure 4 and 5 As shown in , transmitters TX1, TX2, and TX3 are assigned indexes 0, 1, and 2 in the first TX group 302, and transmitters TX7, TX8, and TX9 are assigned indexes 0, 1, and 2 in the second TX group 304. When applying phase offsets to transmitters of the same index, the MCU 104 can use the same DDM code. As shown, transmitters TX1 and TX7 are each assigned to index 0 of their respective TX groups and are encoded with the same progressive phase offset of 0 degrees (e.g., using DDM code code0). Transmitters TX2 and TX8 are each assigned to index 1 of their respective TX groups and are encoded with the same progressive phase offset of 95.625 degrees (e.g., using DDM code code1). Transmitters TX3 and TX9 are each assigned to index 2 of their respective TX groups and are encoded with the same progressive phase offset of 241.875 degrees (e.g., using DDM code code2).

[0066] like Figure 4 and 5 , the transmission periods during which transmitters TX1, TX2, and TX3 of TX group 302 are selected for transmission do not overlap relative to the transmission periods during which transmitters TX7, TX8, and TX9 of TX group 304 are selected for transmission. This may be due, at least in part, to the MCU 104 being configured to select a single TX group to transmit in each time period according to a random or pseudo-random TDM method, as described above.

[0067] Figure 6 An illustrative process flow of method 600 is shown by which raw data corresponding to a sampled return signal is compared with a transmitted signal (eg, a chirp transmitted according to a hybrid RTDM-DDM scheme, such as Figure 3 Figure 300 and Figure 4 and 5 The method 600 corresponds to a reflection of a chirp (shown in timing diagrams 400 and 500) reflected by a target object in the environment surrounding the hybrid RTDM-DDM MIMO radar system. According to one or more embodiments, the method 600 may be performed using either or both of a radar controller and a signal processor of a radar MCU. Figure 1 The method 600 is described with reference to the elements of the radar system 100. 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 600 in one or more other embodiments.

[0068] At block 602, 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 may be output by the ADC 130 as digital signals. These ADC samples represent received signals (sometimes referred to as “reflected signals” or “returned signals”) corresponding to reflections of a transmit signal (i.e., a chirp) transmitted by a first TX group including the transmitter module 118 and a first subset of transmit antenna elements 126 (e.g., according to a hybrid RTDM-DDM scheme, e.g., Figure 3 and 4 300 and 400 of the hybrid RTDM-DDM scheme shown in FIG. 1 ), where the transmit signal is reflected by one or more target objects in the environment of the radar system 100. The return signal is received by the receiver module 128 via the receive antenna element 142.

[0069] At block 604, the signal processor 110 performs range compression of the raw ADC samples associated with the first TX group by performing a fast time FFT or DFT on the raw ADC samples. For example, the signal processor 110 may generate a first range chirped antenna cube (RCAC) associated with the first TX group as an output of this fast time FFT or DFT.

[0070] At block 606, the signal processor 110 performs Doppler compression of the first RCAC by performing a slow time FFT or DFT on the first RCAC. The signal processor 110 may generate a first RDAC as the output of this slow time FFT or DFT. The first RDAC may be a three-dimensional array comprising a first dimension representing a Doppler partition, a second dimension representing a distance partition, and a third dimension representing an RX channel (e.g., corresponding to the number of receiving antenna elements 142 or the number of receiver modules 128) represented in the RDAC. In this document, the third dimension is sometimes referred to as a "channel dimension" in the context of the RDAC and the distance partition matrix extracted therefrom. Each element of the first RDAC may encode the complex amplitude value of the received signal for a specific distance partition, Doppler partition, and RX channel. In one or more embodiments, a given RX channel slice of the RDAC may be represented as a two-dimensional (2D) array of distance-Doppler cells (e.g., represented as RDM), wherein the complex amplitude value of each cell corresponds to the average complex amplitude value within the region boundary in Cartesian space through the corresponding iso-Doppler lines and iso-distance lines. That is, in one or more such embodiments, the boundary of each range partition of the first RDAC is defined by a corresponding pair of equidistance lines, and the boundary of each Doppler partition is defined by a corresponding pair of equi-Doppler lines. Each range-Doppler unit of the first RDAC corresponds to a corresponding Doppler partition and a range partition pair.

[0071] Because the transmitter modules 118 of the first TX group transmit chirps simultaneously in the hybrid RTDM-DDM MIMO radar system when active during a given transmission period, information from all TX channels associated with the first TX group is represented in each element / cell in the first RDAC. Each range partition represents the distance or spacing between the radar system and the target object. Each Doppler partition represents a Doppler shift value corresponding to the speed at which the target object may be traveling (e.g., relative to the self-speed of the radar system 100). Such speed can be calculated based on the determined Doppler shift associated with the target object.

[0072] At block 608, the signal processor 110 of the MCU 104 of the radar system 100 receives raw sample data (“ADC samples”) from one or more ADCs 130 of the receiver module 128. These ADC samples may be output by the ADC 130 as digital signals. These ADC samples represent received signals corresponding to reflections of a transmit signal (i.e., a chirp) transmitted by a second TX group including the transmitter module 118 and a second subset of transmit antenna elements 126 (e.g., according to a hybrid RTDM-DDM scheme, e.g., Figure 3 and 5300 and 500 of the hybrid RTDM-DDM scheme shown in FIG. 1 ), where the transmit signal is reflected by one or more target objects in the environment of the radar system 100. The return signal is received by the receiver module 128 via the receive antenna element 142.

[0073] At block 610, the signal processor 110 performs range compression of the raw ADC samples associated with the second TX group by performing a fast time FFT or DFT on the raw ADC samples. For example, the signal processor 110 may generate a second RCAC associated with the second TX group as an output of this fast time FFT or DFT.

[0074] At block 612, the signal processor 110 performs Doppler compression on the second RCAC by performing a slow-time FFT or DFT on the second RCAC. The signal processor 110 may generate a second RDAC as an output of this slow-time FFT or DFT. Similar to the first RDAC generated at block 606, the second RDAC may be a three-dimensional array, where each range-Doppler cell of the second RDAC represents a range partition or equirange line, a Doppler partition or equiDoppler line, and a receive channel or receive antenna, as described above.

[0075] Because the transmitter modules 118 of the second TX group transmit chirps simultaneously in the hybrid RTDM-DDM MIMO radar system when active during a given transmission period, information from all TX channels associated with the second TX group is represented in each element / cell in the second RDAC.

[0076] At block 614, the signal processor 110 performs non-coherent integration of the first RDAC and the second RDAC to produce a combined RDM. The combined RDM may represent detected reflections corresponding to transmit signals from both the first TX group and the second TX group.

[0077] Although the integration of the first RDAC and the second RDAC is described in this example as being incoherent, this is intended to be illustrative and not limiting. For example, in one or more other embodiments, the signal processor 110 may perform coherent integration of the first RDAC and the second RDAC to generate a combined RDM.

[0078] At block 616, the signal processor 110 detects the peak of the combined RDM (ie, the Doppler spectrum peak) using a suitable peak detection technique. As a non-limiting example, the signal processor 110 may perform CFAR peak detection to identify the peak of the combined RDM.

[0079] Although two RDACs corresponding to two TX groups are generated in this example, it should be understood that this is illustrative and not limiting. In one or more other embodiments, the transmitters of the radar system 100 may be divided into m TX groups, each TX group including M / m transmitters, where M is the total number of transmitters included in the radar system 100, and the signal processor 110 may then be configured to generate m RDACs, each RDAC corresponding to a corresponding TX group. In one or more such embodiments, all m RDACs are non-coherently integrated at block 614 to generate a combined RDM.

[0080] Each of the m RDACs includes N RDMs, one RDM for each RX channel of the radar system 100. Compared to a conventional DDM radar system that produces a single RDAC including a total of N RDMs, given N receive channels, embodiments of the hybrid RTDM-DDM MIMO approach of the present invention produce a total of N*m RDMs in the m RDACs, such that the non-coherently integrated combined RDM produced at block 614 may have an advantageously higher gain than a single RDM produced by such a conventional DDM radar system.

[0081] At block 618, the signal processor 110 performs DDM decoding of the combined RDM based at least in part on the detected peaks to produce a transmitter-associated peak detection (i.e., Doppler spectrum peak detection). For example, a decoder (e.g., a CPC decoder) included in or implemented by the signal processor 110 may perform Doppler disambiguation by decoding the combined RDM (i.e., to produce a decoded RDM) to associate the Doppler spectrum peak detected at block 616 with a corresponding transmitter module in the transmitter module 118.

[0082] At block 620, the signal processor 110 constructs a MIMO array (e.g., corresponding to a virtual MIMO aperture) based on the decoded RDM and the peak detection associated with the transmitters using monostatic and / or bistatic radar principles. To this end, the estimated Doppler shift or radial velocity may be determined by the partition position relative to the zero radial velocity partition of each transmitter, and the receiver outputs of the same radial velocity (i.e., the same relative number of partitions) are grouped according to a standard MIMO virtual array construction process to form a MIMO array output.

[0083] At block 622, the signal processor 110 generates target object location data based on the MIMO array using the angle estimate. In one or more embodiments, the signal processor may generate the target object location data by performing a spatial FFT or an angular FFT on the MIMO array.

[0084] At block 624, the signal processor 110 generates target object tracking data (i.e., a "target track") based on the target object position data. In one or more embodiments, the signal processor 110 may output the resulting target track (e.g., via the interface 106) to other vehicle computing devices or user interface devices for further processing or display.

[0085] The foregoing description refers to elements or nodes or features being "connected" or "coupled" together. As used herein, unless otherwise expressly stated, "connected" means that one element is directly connected to (or directly communicates with) another element, and not necessarily mechanically. Likewise, unless otherwise expressly stated, "coupled" means that one element is directly or indirectly connected to (or directly or indirectly communicates with) another element, and not necessarily mechanically. Thus, although the schematic diagrams shown in the figures depict one exemplary arrangement of elements, additional intervening elements, devices, features, or components may be present in one or more embodiments of the depicted subject matter.

[0086] Although the operations of the methods herein are shown and described in a particular order, the order of operations of each method may be changed so that some operations may be performed in reverse order, or some operations may be performed at least partially simultaneously with other operations. In another embodiment, instructions or sub-operations of different operations may be implemented in an intermittent and / or alternating manner.

[0087] It should also be noted that at least some of the operations of the methods described herein can be implemented using software instructions stored on a computer-usable storage medium for computer execution. For example, an embodiment of a computer program product includes a computer-usable storage medium for storing a computer-readable program. The computer-usable or computer-readable storage medium can be an electronic, magnetic, optical, electromagnetic, infrared or semiconductor system (or device or apparatus). Examples of non-temporary computer-usable and computer-readable storage media include semiconductor or solid-state memory, magnetic tape, removable computer disk, random access memory (RAM), read-only memory (ROM), hard disk and optical disk. Current examples of optical disks include optical disks with read-only memory (CD-ROM), optical disks with read / write (CD-R / W) and digital video disks (DVD).

[0088] Alternatively, the embodiments described herein may be implemented entirely in hardware or in implementation schemes containing both hardware elements and software elements. In embodiments using software, the software may include but is not limited to firmware, resident software, microcode, etc.

[0089] Although at least one exemplary embodiment has been presented in the foregoing specific embodiments, it should be understood that there are a large number of variations. It should also be understood that the exemplary embodiment or multiple exemplary 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 specific embodiments will provide a convenient guide for implementing the described embodiment or embodiments to those skilled in the art. 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, and the scope defined by the claims includes known equivalents and foreseeable equivalents at the time of filing this patent application.

Claims

1. A radar system, characterized in that: include: a plurality of transmitter groups, each transmitter group comprising a plurality of transmitter modules, the plurality of transmitter groups being configured to transmit a plurality of transmission signals according to a random time division multiplexing (RTDM)-Doppler domain multiplexing (DDM) scheme; a plurality of receiver modules configured to receive reflections of the plurality of transmit signals reflected by at least one object and to generate digital signals based on the received reflections; as well as A controller comprising: A signal processor configured to: generating a plurality of range-Doppler antenna cubes (RDACs) based on the reflections of the plurality of transmit signals, each RDAC of the plurality of RDACs corresponding to a respective transmitter group of the plurality of transmitter groups; generating a combined range-Doppler map (RDM) by integrating the plurality of RDACs; and Object position data is generated based on the combined RDM.

2. The radar system according to claim 1, characterized in that The signal processor for generating the plurality of RDACs is additionally configured to: generating a first RDAC by performing range compression and Doppler compression on raw analog-to-digital converter (ADC) data representing a first reflection associated with a first transmit signal of a first transmitter group of the plurality of transmitter groups; and A second RDAC is generated by performing range compression and Doppler compression on raw ADC data representing second reflections associated with a second transmit signal of a second transmitter group of the plurality of transmitter groups.

3. The radar system according to claim 1, characterized in that The controller is configured to: For each transmission period in a given radar transmission frame, only one transmitter group of the plurality of transmitter groups is randomly selected to transmit during the transmission period.

4. The radar system according to claim 3, characterized in that The controller is further configured to: In a first transmission period of the radar transmission frame, randomly selecting a first transmitter group among the plurality of transmitter groups to transmit; and In a second transmission period of the radar transmission frame, a second transmitter group among the plurality of transmitter groups is randomly selected to transmit, wherein the second transmitter group was inactive during the first transmission period and the first transmitter group was inactive during the second transmission period.

5. The radar system according to claim 3, characterized in that Each transmitter module of the plurality of transmitter modules of the plurality of transmitter groups includes a phase rotator configured to apply a phase shift to a transmit signal generated by the transmitter module based on a predefined DDM code.

6. A method, characterized in that include: transmitting a plurality of transmission signals by a plurality of transmitter groups of the radar system according to a random time division multiplexing (RTDM)-Doppler domain multiplexing (DDM) scheme, wherein each transmitter group of the plurality of transmitter groups includes a plurality of transmitter modules; receiving, by a plurality of receiver modules of the radar system, reflections of the plurality of transmit signals reflected by at least one object; generating, by the plurality of receiver modules, digital signals based on the received reflections; as well as generating, by a signal processor of a controller of the radar system, a plurality of range-Doppler antenna cubes (RDACs) based on the reflections of the plurality of transmit signals, each RDAC of the plurality of RDACs corresponding to a respective one of the plurality of transmitter groups; generating a combined RDM by integrating the plurality of RDACs by the signal processor; as well as Object position data is generated by the signal processor based on the combined RDM.

7. The method according to claim 6, characterized in that Generating the plurality of RDACs further comprises: generating, by the signal processor, a first RDAC by performing range compression and Doppler compression on raw analog-to-digital converter (ADC) data representing first reflections associated with a first transmit signal of a first transmitter group of the plurality of transmitter groups; and A second RDAC is generated by the signal processor by performing range compression and Doppler compression on raw ADC data representing second reflections associated with a second transmit signal of a second transmitter group of the plurality of transmitter groups.

8. The method according to claim 6, characterized in that Also includes: For each transmission period in a given radar transmission frame, only one transmitter group of the plurality of transmitter groups is randomly selected by the controller to transmit during the transmission period.

9. The method according to claim 8, characterized in that Also includes: randomly selecting, by the controller, a first transmitter group from among the plurality of transmitter groups for transmission in a first transmission period of the radar transmission frame; as well as randomly selecting, by the controller, a second transmitter group from among the plurality of transmitter groups for transmission in a second transmission period of the radar transmission frame; configuring, by the controller, the second transmitter group to be inactive during the first transmission period; as well as The first transmitter group is configured, by the controller, to be inactive during the second transmission period.

10. The method according to claim 8, characterized in that Also includes: A phase shift is applied by a phase rotator of a transmitter module of the plurality of transmitter modules to a transmit signal generated by the transmitter module based on a predefined DDM code.

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