Signal transmission method and device, signal processing method and device, and radar system

Abstract

A signal transmission method and apparatus, a signal processing method and apparatus, and a radar system are provided to enable a MIMO radar to accurately return the velocity of a target within the velocity measurement range of a SIMO radar. The signal transmission method is applied to a multiple-input multiple-output (MIMO) radar, and the MIMO radar includes a transmitter, the transmitter including multiple transmit antennas. The signal transmission method includes the steps of: transmitting a first burst in a first measurement frame by the transmitter, the first measurement frame being used to measure the velocity of the target, and each of the multiple transmit antennas transmits a chirp signal in a time-division multiplexed manner when the first burst is transmitted; and transmitting a second burst in the first measurement frame by the transmitter after the transmitter transmits the first burst, the number of transmit antennas configured to transmit the chirp signal when the second burst is transmitted is one.

Description

[Technical Field]

[0001] The present application relates to the field of sensor technology, and in particular to signal transmission methods and devices, signal processing methods and devices, and radar systems. [Background technology]

[0002] On-board radar is an essential sensor in autonomous driving systems. A vehicle may be equipped with obstacle (also called target) detection using on-board radar. Specifically, the distance, speed, and azimuth angle of obstacles around the vehicle may be detected.

[0003] In recent years, automotive radar technology has been evolving. For example, the frequency band gradually evolves from 24 GHz to 77 GHz / 79 GHz to obtain higher range resolution by using larger sweep bandwidth. In order to expand the virtual antenna aperture and improve angular resolution, the number of channels evolves from single input multiple output (SIMO) mode to multiple input multiple output (MIMO) mode.

[0004] In MIMO radar, multiple antennas may transmit chirp signals using a time division multiplexing (TDM) scheme. MIMO radar can improve angular resolution, but it suffers from a reduced maximum velocity measurement range. Generally, the maximum velocity measurement range of a radar can be expressed as Vmax = λ / 4*Tc, where λ is the wavelength for frequency modulation and Tc is the transmission repetition period of the same antenna. Assume that the duration of transmitting one chirp signal by a single antenna is Tc_SIMO (sometimes called a time slot). Then, in TDM MIMO radar, when Nt antennas transmit Nt chirp signals using TDM, the required time Tc_MIMO satisfies Tc_MIMO ≥ Nt*Tc_SIMO. Therefore, the relationship between the maximum velocity measurement range Vmax_MIMO when Nt antennas are configured to transmit chirps and the maximum velocity measurement range Vmax_SIMO when a single antenna is configured to transmit chirps (i.e., the velocity measurement range of a SIMO radar) can be expressed as Vmax_SIMO≧Nt*Vmax_MIMO. From the above equation, we can see that the maximum velocity measurement range of a MIMO radar is reduced compared to that of a SIMO radar due to the large number of transmit antennas. Furthermore, a large number of transmit antennas, Nt, indicates a more serious problem: a reduced maximum velocity measurement range. A reduced maximum velocity measurement range makes velocity aliasing more likely to occur when calculating the target velocity. Additionally, due to the measurement coupling between velocity and angle in a TDM MIMO radar, velocity aliasing affects the angular resolution, resulting in failure to achieve the desired goal of improving angular resolution.

[0005] In conclusion, there is an urgent need for signal transmission and processing solutions for MIMO radar so that the MIMO radar can accurately return the target velocity within the velocity measurement range of the SIMO radar. Summary of the Invention [Means for solving the problem]

[0006] The embodiments of the present application provide a signal transmission method and apparatus, a signal processing method and apparatus, and a radar system so that the MIMO radar can accurately return the velocity of a target within the velocity measurement range of the SIMO radar.

[0007] According to a first aspect, an embodiment of the present application provides a signal transmission method. The method is applied to a multiple-input multiple-output (MIMO) radar, and the MIMO radar includes a transmitter, the transmitter including multiple transmit antennas. The signal transmission method includes the transmitter transmitting a first burst in a first measurement frame. The first measurement frame is used to measure the velocity of a target, and when the first burst is transmitted, each of the multiple transmit antennas transmits a chirp signal in a time-division manner. After transmitting the first burst in the first measurement frame, the transmitter transmits a second burst in the first measurement frame. When the second burst is transmitted, the number of transmit antennas configured to transmit the chirp signal is one.

[0008] According to the above solution, target velocity range searching is performed using the echo signal formed after the first burst transmitted in the MIMO manner is reflected and the echo signal formed after the second burst transmitted in the SIMO manner after the first burst is reflected. By matching, velocity aliasing coefficients of one or more targets can be obtained, and the velocity measurement range of the MIMO radar can be restored to the velocity measurement range of the SIMO radar. In addition, the complexity of the MIMO spectrum peak search can be reduced, and the influence of channel phase noise on overlap can be reduced. In addition, since the strength of the echo signal is inversely proportional to the fourth power of the distance, when a SIMO burst (i.e., the second burst) is transmitted after a MIMO burst (i.e., the first burst), the fast-moving target can move closer within the SIMO burst. As a result, the problem of the weak echo signal of the fast-moving target within the SIMO burst can be alleviated to some extent.

[0009] Additionally, the method further includes the transmitter transmitting a third burst in the first measurement frame before transmitting the first burst in the first measurement frame. When the third burst is transmitted, the number of transmit antennas configured to transmit chirp signals is 1, and the transmit antenna configured to transmit the third burst is the same as the transmit antenna configured to transmit the second burst. The transmitter transmits the first measurement frame with a duty cycle of P%, P<100, where the duty cycle is equal to the ratio of the first duration to the second duration. The first duration is the duration of the first measurement frame, and the second duration is the time difference between two adjacent measurement frames transmitted by the transmitter. According to the above solution, three bursts are transmitted in one measurement frame, the first burst transmitted at the middle position is transmitted using a MIMO scheme, and the prefix and suffix of the first burst are transmitted using a SIMO scheme. Then, when the echo signal formed after the measurement frame is reflected by one or more targets is processed, two bursts transmitted in the SIMO manner can be selected for velocity matching, making target velocity calculation easier. This also alleviates the problem of the scattering center of a fast-moving target moving over the transmission time to some extent. Furthermore, since the transmitter transmits the first measurement frame with a duty cycle of P%, in each measurement period, there is an idle time and processing time after the measurement frame is transmitted and before the next measurement frame is transmitted. For this purpose, the duty cycle P% exists.

[0010] Additionally, the method further includes transmitting a fourth burst in a second measurement frame after the transmitter transmits the first measurement frame. The second measurement frame is used to measure the velocity of the target, and when the fourth burst is transmitted, each of the multiple transmit antennas transmits a chirp signal in a time-division manner. After transmitting the fourth burst in the second measurement frame, the transmitter transmits a fifth burst in the second measurement frame. When the fifth burst is transmitted, the number of transmit antennas configured to transmit chirp signals is one, and the transmission parameters of the fifth burst, the second burst, and the third burst are the same. Specifically, the transmission parameters include a transmission slope, a transmit antenna, the number of transmitted chirp signals, the duration of each chirp signal, etc. According to the above solution, when calculating the velocity of the target, the second burst in the first measurement frame can be regarded as a SIMO prefix in the second measurement frame to reduce transmission overhead.

[0011] In one possible design, the number of chirp signals transmitted by the multiple transmit antennas in the first burst is different from each other. According to the above solution, when the number of chirp signals transmitted by the transmit antennas in the first burst is different from each other, the complexity of the spectral peak search can be further reduced by using high-density transmit antennas.

[0012] In one possible design, the first measurement frame is one of a frequency modulated continuous wave (FMCW), multiple frequency shift keying (MFSK), or phase modulated continuous wave (PMCW).

[0013] Additionally, the MIMO radar may further include a processing unit, and the method may further include the processing unit determining a configuration of the first measurement frame and transmitting the configuration of the first measurement frame to a monolithic microwave integrated circuit (MMIC) using the interface. The MMIC is configured to enable the transmitter to transmit the first measurement frame based on the configuration of the first measurement frame. According to the above solution, related parameters for the MMIC can be configured to complete the transmission of the first measurement frame.

[0014] According to a second aspect, an embodiment of the present application further provides a signal processing method. The method is applied to a MIMO radar, the MIMO radar including a transmitter, a receiver, and a processing unit, and the transmitter includes multiple transmit antennas. Specifically, the signal processing method includes the receiver receiving a first echo signal and a second echo signal. The first echo signal is formed after a first burst in a measurement frame transmitted by the transmitter is reflected by one or more targets, and the second echo signal is formed after a second burst in the measurement frame is reflected by one or more targets, the second burst being transmitted after the first burst. When the first burst is transmitted, each of the multiple transmit antennas transmits a chirp signal in a time-division manner. When the second burst is transmitted, the number of transmit antennas configured to transmit the chirp signal is one. The processing unit determines the velocity of the one or more targets based on the echo signals received by the receiver.

[0015] According to a signal processing method provided in a second aspect, an echo signal formed after a first burst transmitted in a MIMO manner is reflected and an echo signal formed after a second burst transmitted in a SIMO manner after the first burst is reflected are used, and velocity aliasing coefficients of one or more targets are obtained by matching, and the velocity measurement range of the MIMO radar can be restored to the velocity measurement range of the SIMO radar.

[0016] In one possible design, the processing unit determining the velocity of the one or more targets based on the echo signals received by the receiver includes the processing unit determining a first identifier based on the first echo signal. The first identifier is used to indicate a range measurement and a velocity measurement of the one or more targets. The processing unit determines a second identifier based on the second echo signal. The second identifier is used to indicate a range measurement and a velocity measurement of the one or more targets. The processing unit determines the velocity of the one or more targets based on the first identifier and the second identifier. According to the aforementioned solution, a velocity aliasing coefficient of the target may be determined based on two groups of identifiers of the target (i.e., the first identifier and the second identifier) ​​to determine the velocity of the target.

[0017] In one possible design, the processing unit determining the velocity of the one or more targets based on the first identifier and the second identifier includes the processing unit determining an aliasing coefficient interval corresponding to the first identifier based on a transmit repetition period of the first transmit antenna in the first burst. The processing unit determines an aliasing coefficient subset based on the first identifier, the second identifier, and the aliasing coefficient interval. The processing unit determines velocity aliasing coefficients based on the aliasing coefficient subset. The processing unit determines the velocity of the one or more targets based on the velocity aliasing coefficients and the first identifier.

[0018] The method further includes the receiver receiving a third echo signal. The third echo signal is formed after a third burst in the measurement frame is reflected by one or more targets, the third burst being transmitted before the first burst. The processing unit determining the velocity of the one or more targets based on the echo signals received by the receiver includes the processing unit determining the velocity of the one or more targets based on the first echo signal and the third echo signal if the one or more targets move away from the radar system. If the one or more targets move toward the radar system, the processing unit determines the velocity of the one or more targets based on the first echo signal and the second echo signal. According to the above solution, since the target actually moves within the three bursts, for distant targets, such movement affects the strength of the received signal from the target. As the target moves away, the distance between the target and the second burst increases, reducing the strength of the signal from the target and increasing the reliability of the data in the third burst. As the target approaches, the distance to the target in the second burst decreases, the strength of the signal from the target increases, and the data in the second burst becomes more reliable.

[0019] In one possible design, the processing unit's determining velocity aliasing coefficients based on the aliasing coefficient subset includes the processing unit determining observations of a virtual MIMO subarray based on echo signals received by the receiver. The processing unit determines the velocity aliasing coefficients based on the observations of the virtual MIMO subarray. The virtual MIMO subarray is a uniform planar subarray or a uniform linear subarray including virtual array elements in the virtual array, where each transmit antenna corresponds to the same number of virtual array elements in the virtual MIMO subarray, and the virtual array includes multiple transmit antennas and multiple receive antennas included in the receiver. According to the above solution, the angular spectrum can be calculated by selecting multiple array elements in the virtual array to form the virtual MIMO subarray and performing an FFT on the observations of the virtual MIMO subarray.

[0020] In one possible design, the processing unit's determining velocity aliasing coefficients based on the aliasing coefficient subset includes the processing unit determining observations of a virtual MIMO subarray based on echo signals received by the receiver. The processing unit determines the velocity aliasing coefficients based on the observations of the virtual MIMO subarray. The virtual MIMO subarray is a uniform planar subarray or a uniform linear subarray including virtual array elements in the virtual array, where the uniform planar subarray and the uniform linear subarray are obtained by linear interpolation, each transmit antenna corresponds to the same number of virtual array elements in the virtual MIMO subarray, and the virtual array includes multiple transmit antennas and multiple receive antennas included in the receiver. According to the above solution, if a virtual MIMO subarray that satisfies the conditions (i.e., all array elements in the MIMO subarray are equally spaced and each transmit antenna corresponds to the same number of virtual array elements in the virtual MIMO subarray) cannot be found in the virtual array, the virtual MIMO subarray can be formed by linear interpolation.

[0021] According to a third aspect, an embodiment of the present application provides a signal transmission device, the signal transmission device including: a transmitter including a plurality of transmitting antennas, the transmitter being configured to: transmit a first burst in a first measurement frame, the first measurement frame being used to measure the velocity of a target, and when the first burst is transmitted, each of the plurality of transmitting antennas transmits a chirp signal in a time division manner; and transmit a second burst in the first measurement frame after transmitting the first burst in the first measurement frame, wherein when the second burst is transmitted, the number of transmitting antennas configured to transmit the chirp signal is one.

[0022] In one possible design, the transmitter is further configured to transmit a third burst in the first measurement frame before transmitting the first burst in the first measurement frame. When the third burst is transmitted, the number of transmit antennas configured to transmit chirp signals is 1, and the transmit antenna configured to transmit the third burst and the transmit antenna configured to transmit the second burst are the same transmit antenna. The transmitter transmits the first measurement frame with a duty cycle of P%, P<100, where the duty cycle is equal to a ratio of the first duration to the second duration, the first duration is the duration of the first measurement frame, and the second duration is a time difference between two adjacent measurement frames transmitted by the transmitter.

[0023] In one possible design, the transmitter is further configured to transmit a fourth burst in a second measurement frame after transmitting the first measurement frame, the second measurement frame being used to measure the velocity of the target, and when the fourth burst is transmitted, each of the multiple transmit antennas transmits chirp signals in a time-division manner, the transmitter is configured to transmit a fifth burst in the second measurement frame after transmitting the fourth burst in the second measurement frame, and when the fifth burst is transmitted, the number of transmit antennas configured to transmit chirp signals is one, and transmission parameters of the fifth burst, the second burst, and the third burst are the same.

[0024] The transmission parameters include one or more of a transmission slope, a transmission antenna, a number of transmitted chirp signals, or a duration of each chirp signal.

[0025] In one possible design, the first measurement frame is one of a frequency modulated continuous wave (FMCW), multiple frequency shift keying (MFSK), or phase modulated continuous wave (PMCW).

[0026] In one possible design, the apparatus further includes a processing unit configured to determine a configuration of the first measurement frame and to transmit the configuration of the first measurement frame to a monolithic microwave integrated circuit (MMIC) using the interface, the MMIC configured to enable the transmitter to transmit the first measurement frame based on the configuration of the first measurement frame.

[0027] According to a fourth aspect, an embodiment of the present application provides a signal processing device, the signal processing device including: a receiver configured to receive a first echo signal and a second echo signal, wherein the first echo signal is formed after a first burst in a measurement frame transmitted by a transmitter is reflected by one or more targets, and the second echo signal is formed after a second burst in the measurement frame is reflected by the one or more targets, the second burst being transmitted after the first burst, wherein when the first burst is transmitted, each of a plurality of transmitting antennas transmits a chirp signal in a time-division manner, and when the second burst is transmitted, the number of transmitting antennas configured to transmit the chirp signal is one; and a processing unit configured to determine a velocity of the one or more targets based on the echo signals received by the receiver.

[0028] In one possible design, when determining the velocity of one or more targets based on the echo signals received by the receiver, the processing unit is specifically configured to: determine a first identifier based on the first echo signal, where the first identifier is used to indicate range and velocity measurements of the one or more targets; determine a second identifier based on the second echo signal, where the second identifier is used to indicate range and velocity measurements of the one or more targets; and determine the velocity of the one or more targets based on the first identifier and the second identifier.

[0029] In one possible design, when determining the velocity of the one or more targets based on the first identifier and the second identifier, the processing unit is specifically configured to: determine an aliasing coefficient interval corresponding to the first identifier based on a transmit repetition period of the first transmit antenna in the first burst; determine an aliasing coefficient subset based on the first identifier, the second identifier, and the aliasing coefficient interval; determine a velocity aliasing coefficient based on the aliasing coefficient subset; and determine the velocity of the one or more targets based on the velocity aliasing coefficient and the first identifier.

[0030] In one possible design, the receiver is further configured to receive a third echo signal. The third echo signal is formed after a third burst in the measurement frame is reflected by one or more targets, the third burst being transmitted before the first burst. When determining the velocity of the one or more targets based on the echo signals received by the receiver, the processing unit is specifically configured to: determine the velocity of the one or more targets based on the first and third echo signals if the one or more targets move away from the radar system; and determine the velocity of the one or more targets based on the first and second echo signals if the one or more targets move toward the radar system.

[0031] In one possible design, when determining velocity aliasing coefficients based on the aliasing coefficient subset, the processing unit is specifically configured to determine observation results of a virtual MIMO subarray based on echo signals received by the receiver, and to determine the velocity aliasing coefficients based on the observation results of the virtual MIMO subarray. The virtual MIMO subarray is a uniform planar subarray or a uniform linear subarray including virtual array elements in the virtual array, where each transmit antenna corresponds to the same number of virtual array elements in the virtual MIMO subarray, and the virtual array includes multiple transmit antennas and multiple receive antennas included in the receiver.

[0032] In one possible design, when determining velocity aliasing coefficients based on the aliasing coefficient subset, the processing unit is specifically configured to determine observations of a virtual MIMO subarray based on echo signals received by the receiver, and to determine the velocity aliasing coefficients based on the observations of the virtual MIMO subarray. The virtual MIMO subarray is a uniform planar subarray or a uniform linear subarray including virtual array elements in the virtual array, the uniform planar subarray and the uniform linear subarray are obtained by linear interpolation, each transmit antenna corresponds to the same number of virtual array elements in the virtual MIMO subarray, and the virtual array includes multiple transmit antennas and multiple receive antennas included in the receiver.

[0033] According to a fifth aspect, an embodiment of the present application provides a radar system, the radar system including: a transmitter including a plurality of transmitting antennas configured to transmit a first burst in a measurement frame, the measurement frame being used to measure a velocity of a target, wherein when the first burst is transmitted, each of the plurality of transmitting antennas transmits a chirp signal in a time-division manner; and transmitting a second burst in the measurement frame after transmitting the first burst, wherein when the second burst is transmitted, the number of transmitting antennas configured to transmit the chirp signal is one; a receiver configured to receive a first echo signal and a second echo signal, the first echo signal being formed after the first burst is reflected by one or more targets, and the second echo signal being formed after the second burst is reflected by one or more targets; and a processing unit configured to determine the velocity of the one or more targets based on the echo signals received by the receiver. [Brief explanation of the drawings]

[0034] [Figure 1]1 is a schematic diagram of the structure of a MIMO radar according to an embodiment of the present application; [Figure 2] 1 is a schematic diagram of a vehicle structure according to an embodiment of the present application; [Figure 3] 1 is a schematic diagram of a flowchart of a signal transmission method according to an embodiment of the present application; [Figure 4] FIG. 2 is a schematic diagram of a chirp signal transmitted by a first MIMO radar according to an embodiment of the present application; [Figure 5] FIG. 10 is a schematic diagram of a chirp signal transmitted by a second MIMO radar according to an embodiment of the present application; [Figure 6] FIG. 10 is a schematic diagram of a chirp signal transmitted by a third MIMO radar according to an embodiment of the present application; [Figure 7] FIG. 10 is a schematic diagram of a chirp signal transmitted by a fourth MIMO radar according to an embodiment of the present application; [Figure 8] FIG. 10 is a schematic diagram of a chirp signal transmitted by a fifth MIMO radar according to an embodiment of the present application; [Figure 9] 1 is a schematic diagram of a flow chart of a signal processing method according to an embodiment of the present application; [Figure 10] FIG. 2 is a schematic diagram of a first virtual MIMO sub-array according to an embodiment of the present application; [Figure 11] 1 is a schematic diagram of an antenna array according to an embodiment of the present application; [Figure 12] FIG. 2 is a schematic diagram of a second virtual MIMO sub-array according to an embodiment of the present application. [Figure 13] FIG. 10 is a schematic diagram of a third virtual MIMO sub-array according to an embodiment of the present application. [Figure 14] 1 is a schematic diagram of the structure of a signal transmitting device according to an embodiment of the present application; [Figure 15] 1 is a schematic diagram of the structure of a signal processing device according to an embodiment of the present application; [Figure 16] 1 is a schematic diagram of the structure of a radar system according to an embodiment of the present application; DETAILED DESCRIPTION OF THE INVENTION

[0035] In general, the maximum velocity measurement range of a radar can be expressed as Vmax = λ / 4*Tc, where λ is the wavelength for frequency modulation and Tc is the transmission repetition period of the same antenna. Assume that the duration of transmitting one chirp signal by a single antenna is Tc_SIMO (sometimes called a time slot). Then, in a TDM MIMO radar, when Nt antennas transmit Nt chirp signals in a TDM manner, the required time Tc_MIMO satisfies Tc_MIMO ≥ Nt * Tc_SIMO. Therefore, the relationship between the maximum velocity measurement range Vmax_MIMO when Nt antennas are configured to transmit chirps and the maximum velocity measurement range Vmax_SIMO when a single antenna is configured to transmit chirps can be expressed as Vmax_SIMO ≥ Nt * Vmax_MIMO. From the above equation, we can see that in a MIMO radar, the maximum velocity measurement range decreases due to the large number of transmitting antennas. Furthermore, a large number of transmitting antennas, Nt, presents a more serious problem: the maximum velocity measurement range decreases.

[0036] Radar is a device that measures velocity using the Doppler effect. As the target or radar moves, the radar's received signal undergoes frequency or phase changes. In an FMCW system, the distance between the target and the radar is measured by measuring the frequency of the echo signal within the chirp signal, and the target's velocity is measured by the phase difference between the echo signals of the same antenna in different time slots. Therefore, the dimension corresponding to velocity is also called the Doppler domain, i.e., the dimension corresponding to Doppler on the RD map.

[0037] Radar signals transmitted by multiple antennas in a time-division multiplexing manner result in a higher probability of collisions between targets' velocities in the Doppler domain, i.e., the observed values ​​of the reflected signals from multiple targets in the Doppler domain are the same, which affects the complexity and accuracy of the speed solution for each target. For example, when SIMO is used for transmission, the maximum speed measurement range is -120 km / h to 120 km / h. When four antennas are used for transmission using TDM MIMO, the maximum speed measurement range is reduced to -30 km / h to 30 km / h. In this case, compared to transmission using SIMO, transmission using TDM MIMO has a higher probability of collisions between targets' velocities in the Doppler domain.

[0038] Based on the aforementioned problems, the embodiments of the present application provide a signal transmission method and apparatus, a signal processing method and apparatus, and a radar system, so that the MIMO radar can accurately return the velocity of a target within the velocity measurement range of the SIMO radar.

[0039] The following describes an application scenario of one embodiment of the present application.

[0040] Specifically, in this embodiment of the present application, as shown in Figure 1, the MIMO radar system may include an antenna array 101, a monolithic microwave integrated circuit (MMIC) 102, and a processing unit 103. The antenna array 101 may include multiple transmit antennas and multiple receive antennas.

[0041] The monolithic microwave integrated circuit 102 is configured to generate a radar signal and then transmit the radar signal using the antenna array 101. The radar signal includes one or more bursts, and each burst includes multiple chirp signals. After the radar signal is transmitted, an echo signal is formed after the radar signal is reflected by one or more targets, and the echo signal is received by a receiving antenna. The monolithic microwave integrated circuit 102 is further configured to perform processing, such as conversion and sampling, on the echo signal received by the antenna array 101 and transmit the processed echo signal to the processing unit 103.

[0042] The processing unit 103 is configured to perform operations such as Fast Fourier Transformation (FFT) and signal processing on the received echo signals to determine information such as the range, velocity, and azimuth of the target based on the received echo signals. Specifically, the processing unit 103 may be a microprocessor (microcontroller unit (MCU)), a central processing unit (CPU), a digital signal processor (DSP), a field-programmable gate array (FPGA), or other components having processing capabilities.

[0043] In addition, the radar system shown in FIG. 1 may further include an electronic control unit (ECU) 104 configured to control the vehicle, e.g., determine the vehicle path, based on the distance, speed, azimuth, and other information of the target obtained by the processing unit 103 after processing.

[0044] It should be noted that in practical applications, one MMIC may be arranged for each of the transmit and receive antenna arrays, or only one MMIC may be arranged for each of the transmit and receive antenna arrays. The former is shown for illustrative purposes in the example of Figure 1.

[0045] In this embodiment of the present application, the transmitter may include a transmitting antenna and a transmitting channel within the monolithic microwave integrated circuit 102, and the receiver may include a receiving antenna and a receiving channel within the monolithic microwave integrated circuit 102. The transmitting antenna and the receiving antenna may be disposed on a printed circuit board (PCB), and the transmitting channel and the receiving channel may be disposed within the chip, i.e., antenna on PCB (AOB). Alternatively, the transmitting antenna and the receiving antenna may be disposed within a chip package, and the transmitting channel and the receiving channel may be disposed within the chip, i.e., antennas in package (AIP). The combination form is not particularly limited in this embodiment of the present application.

[0046] It should be understood that the specific structures of the transmitting and receiving channels are not limited in this embodiment of the present application, as long as they can implement the corresponding transmitting and receiving functions.

[0047] Furthermore, it should be noted that the radar system in this embodiment of the present application can be applied to various fields, including, but not limited to, automotive radar, roadside traffic radar, and radar for unmanned aerial vehicles.

[0048] In addition, because the number of channels on a single radio frequency chip is limited, if the number of transmit and receive channels required by the system is greater than that of a single radio frequency chip, multiple chips need to be cascaded. Therefore, the entire radar system can include multiple cascaded radio frequency chips, which are connected to analog-to-digital converter (ADC) channels using an interface to output data to a processing unit 103, such as an MCU, DSP, FPGA, or general processing unit (GPU). In addition, one or more radar systems may be installed throughout a vehicle and connected to a central processing unit using an on-board bus. The central processing unit controls one or more on-board sensors, including one or more millimeter-wave radar sensors.

[0049] The MIMO radar system shown in FIG. 1 may be applied to a vehicle with an autonomous driving function. FIG. 2 is a functional block diagram of a vehicle 200 with an autonomous driving function according to one embodiment of the present application. In one embodiment, the vehicle 200 is configured to be in a fully or partially autonomous driving mode. For example, when the vehicle 200 is in the autonomous driving mode, the vehicle 200 can control the vehicle 200, determine the current state of the vehicle and the vehicle's surrounding environment based on manual operation, determine the possible behavior of at least one other vehicle in the surrounding environment, determine a confidence level corresponding to the likelihood that the other vehicle will perform the possible behavior, and control the vehicle 200 based on the determined information. When the vehicle 200 is in the autonomous driving mode, the vehicle 200 can be configured to operate without human interaction.

[0050] Vehicle 200 may include various subsystems, such as a traction system 202, a sensor system 204, a control system 206, one or more peripheral devices 208, a power source 210, a computer system 212, and a user interface 216. Optionally, vehicle 200 may include fewer or more subsystems, and each subsystem may include multiple elements. Additionally, all of the subsystems and elements of vehicle 200 may be interconnected with each other in a wired or wireless manner.

[0051] The traction system 202 may include components that provide powered motion to the vehicle 200. In one embodiment, the traction system 202 may include an engine 218, an energy source 219, a transmission 220, and wheels / tires 221. The engine 218 may be an internal combustion engine, an electric motor, an air-compression engine, or a combination of other types of engines, such as a hybrid engine including a gasoline engine and an electric motor, or a hybrid engine including an internal combustion engine and an air-compression engine. The engine 218 converts the energy source 219 into mechanical energy.

[0052] Examples of energy source 219 include gasoline, diesel, other oil-based fuels, propane, other compressed gas-based fuels, ethanol, solar panels, batteries, and other power sources. Energy source 219 may also provide energy to other systems of vehicle 100.

[0053] The transmission 220 can transmit mechanical power from the engine 218 to the wheels 221. The transmission 220 can include a gearbox, a differential, and a drive shaft. In one embodiment, the transmission 220 can further include other components, such as a clutch. The drive shaft can include one or more shafts that can be coupled to one or more wheels 221.

[0054] The sensor system 204 may include several sensors for sensing information about the vehicle 200's surrounding environment. For example, the sensor system 204 may include a positioning system 222 (which may be a global positioning system (GPS) system, or a BeiDou system or another positioning system), an inertial measurement unit (IMU) 224, a radar 226, a laser range finder 228, and a camera 230. The sensor system 204 may further include sensors within the monitored vehicle 200's internal systems (e.g., an interior air quality monitor, a fuel gauge, and an oil temperature gauge). Sensor data from one or more of these sensors may be used to detect objects and corresponding characteristics of the objects (e.g., position, shape, orientation, speed, etc.). Such detection and identification is a critical function for the safe operation of the automated vehicle 100.

[0055] Positioning system 222 may be configured to estimate the geographic position of vehicle 200. IMU 224 is configured to sense changes in position and orientation of vehicle 200 based on inertial acceleration. In one embodiment, IMU 224 may be a combination of an accelerometer and a gyroscope.

[0056] Radar 226 can detect objects in the environment surrounding vehicle 200 by using radio signals. In some embodiments, in addition to detecting objects, radar 226 may be further configured to detect the speed and / or direction of movement of the objects. In one specific example, radar 226 may be implemented using the MIMO radar system shown in FIG. 1.

[0057] The laser range finder 228 can use lasers to detect objects within the environment in which the vehicle 100 is located. In some embodiments, the laser range finder 228 can include one or more laser sources, a laser scanner, one or more detectors, and other system components.

[0058] Camera 230 may be configured to capture multiple images of the environment surrounding vehicle 200. Camera 230 may be a still camera or a video camera.

[0059] The control system 206 controls the operation of the vehicle 200 and its components. The control system 206 may include various elements, including a steering system 232, an accelerator 234, a braking unit 236, a sensor fusion algorithm 238, a computer vision system 240, a path control system 242, and an obstacle avoidance system 244.

[0060] The steering system 232 may operate to adjust the direction of travel of the vehicle 200, for example, in one embodiment the steering system may be a steering wheel system.

[0061] The axel 234 is configured to control the operating speed of the engine 218 to control the speed of the vehicle 200 .

[0062] The brake unit 236 is configured to control the deceleration of the vehicle 200. The brake unit 236 can decelerate the wheels 221 by using friction. In other embodiments, the brake unit 236 can convert the kinetic energy of the wheels 221 into electric current. Alternatively, the brake unit 236 can decelerate the rotational speed of the wheels 221 in another manner to control the speed of the vehicle 200.

[0063] Computer vision system 240 may operate to process and analyze images captured by camera 230 to recognize objects and / or features within the vehicle 200's surrounding environment. The objects and / or features may include traffic signals, road boundaries, and obstacles. Computer vision system 240 may use object recognition algorithms, structure from motion (SFM) algorithms, video tracking, and other computer vision techniques. In some embodiments, computer vision system 240 may be configured to map the environment, track objects, estimate object speeds, etc.

[0064] The route control system 242 is configured to determine a route for the vehicle 200. In some embodiments, the route control system 142 may reference data from the sensors 238, the GPS 222, and one or more predetermined maps to determine the route for the vehicle 200.

[0065] Obstacle avoidance system 244 is configured to recognize, assess, avoid, or circumvent potential obstacles in the environment of vehicle 200.

[0066] Of course, in one embodiment, the control system 206 may include additional or alternative components other than those shown and described, or may include fewer of the components shown above.

[0067] Vehicle 200 interacts with external sensors, other vehicles, other computer systems, or users through peripherals 208. Peripherals 208 may include a wireless communication system 246, an on-board computer 248, a microphone 250, and / or a speaker 252.

[0068] In some embodiments, peripheral devices 208 provide a means for a user of vehicle 200 to interact with user interface 216. For example, onboard computer 248 can provide information to the user of vehicle 200. User interface 216 can further receive user input via onboard computer 248. Onboard computer 248 may be operated using a touch panel. In other cases, peripheral devices 208 can provide a means for vehicle 200 to communicate with other devices located within the vehicle. For example, microphone 250 can receive audio (e.g., voice commands or other audio input) from the user of vehicle 200. Similarly, speaker 252 may output audio to the user of vehicle 200.

[0069] The wireless communication system 246 may wirelessly communicate with one or more devices directly or through a communication network. For example, the wireless communication system 246 may use 3G cellular communications such as code division multiple access (CDMA), EVD 0, global system for mobile communications (GSM) / general packet radio service (GPRS), or 4G cellular communications such as long term evolution (LTE), or 5G cellular communications. The wireless communication system 246 may communicate with a wireless local area network (WLAN) via Wi-Fi. In some embodiments, the wireless communication system 246 may communicate directly with devices via an infrared link, Bluetooth, or ZigBee. Various vehicle communication systems, such as the wireless communication system 246, may include other wireless protocols, e.g., one or more dedicated short range communications (DSRC) units, which may include public and / or private data communications between vehicles and / or roadside stations.

[0070] Power source 210 may provide power to various components of vehicle 200. In one embodiment, power source 210 may be a rechargeable lithium-ion or lead-acid battery. One or more battery packs of such batteries may be configured as a power source to power the components of vehicle 200. In some embodiments, power source 210 and energy source 219 may be implemented together, such as in some all-electric vehicles.

[0071] Some or all functions of vehicle 200 are controlled by computer system 212. Computer system 212 may include at least one processor 223. Processor 223 executes instructions 225 stored on a non-transitory computer-readable medium, such as memory 224. Alternatively, computer system 212 may be multiple computing devices that control individual components or subsystems of vehicle 200 in a distributed manner.

[0072] The processor 223 may be any conventional processor, such as a commercially available central processing unit (CPU). Alternatively, the processor may be a dedicated device, such as an application-specific integrated circuit (ASIC) or other hardware-based processor. FIG. 2 shows a functional diagram including the processor, memory, and other components of the computer 210 within the same block. Those skilled in the art should understand that a processor, computer, or memory may actually include multiple processors, computers, or memories that may or may not be stored in the same physical housing. For example, the memory may be a hard disk drive or another storage medium located in a housing different from that of the computer 210. Thus, reference to a processor or computer is understood to include reference to a set of processors or computers or memories that may or may not operate in parallel. Unlike using a single processor to perform the steps described herein, some components, such as steering and deceleration components, may include their own processors. The processors perform only calculations related to the component's specific functions.

[0073] In various aspects described herein, the processor may be located remotely from the vehicle and in wireless communication with the vehicle. In other aspects, some of the processes described herein are executed on a processor located within the vehicle, while other processes are executed by a remote processor. These processes include the steps necessary to perform a single operation.

[0074] In some embodiments, memory 224 may include instructions 225 (e.g., program logic) that may be executed by processor 223 to perform various functions of vehicle 200, including those described above. Memory 224 may further include additional instructions, including instructions for transmitting data to, receiving data from, interacting with, and / or controlling one or more of driving system 202, sensor system 204, control system 206, and peripherals 208.

[0075] In addition to instructions 225, memory 224 may further store data such as road maps, route information, vehicle position, vehicle direction, vehicle speed, and other vehicle data, as well as other information that may be used by vehicle 200 and computer system 212 during operation of vehicle 200 in autonomous, semi-autonomous, and / or manual modes.

[0076] User interface 216 is configured to provide information to or receive information from a user of vehicle 200. Optionally, user interface 216 may include one or more input / output devices in set of peripherals 208, such as a wireless communication system 246, an onboard computer 248, a microphone 250, and a speaker 252.

[0077] Computer system 212 may control functions of vehicle 200 based on inputs received from various subsystems (e.g., cruise control system 202, sensor system 204, and control system 206) and user interface 216. For example, computer system 212 may control steering unit 232 by using inputs from control system 206 to avoid obstacles detected by sensor system 204 and obstacle avoidance system 244. In some embodiments, computer system 212 may operate to provide control over many aspects of vehicle 200 and vehicle subsystems.

[0078] Optionally, one or more of the aforementioned components may be located separately from or associated with vehicle 200. For example, memory 224 may be partially or completely separate from vehicle 200. The aforementioned components may be communicatively coupled to each other in a wired and / or wireless manner.

[0079] Optionally, the above components are merely examples. In actual applications, the components in the above modules can be added or deleted according to actual requirements. Figure 2 should not be understood as any limitation on the embodiments of the present application.

[0080] An autonomous vehicle traveling on a road, such as vehicle 200, may identify objects in the vehicle's environment to determine to adjust its current speed. The objects may be other vehicles, traffic control devices, or other types of objects. In some examples, the autonomous vehicle may consider each identified object independently and determine a target speed adjustment for the autonomous vehicle based on characteristics of each identified object, such as the object's current speed, the object's acceleration, and the distance between the object and the vehicle.

[0081] Optionally, autonomous vehicle 200 or a computing device associated with autonomous vehicle 200 (e.g., computer system 212, computer vision system 240, and memory 224 in FIG. 2 ) can predict the behavior of a recognized object based on the characteristics of the recognized object and conditions of the surrounding environment (e.g., traffic volume, rain, or ice on the road). Optionally, all identified objects depend on each other's behavior, and therefore, all identified objects may be considered together to predict the behavior of a single identified object. Vehicle 200 can adjust its speed based on the predicted behavior of the identified object. In other words, autonomous vehicle can determine a stable state (e.g., accelerate, decelerate, or stop) that the vehicle needs to adjust to based on the predicted behavior of the object. This process can also take into account other factors for determining the speed of vehicle 200, such as the horizontal position of vehicle 200 on the road on which the vehicle is traveling, the curvature of the road, and the proximity between stationary and dynamic objects.

[0082] In addition to providing instructions to adjust the speed of the autonomous vehicle, the computing device may further provide instructions to change the steering angle of vehicle 200 so that the autonomous vehicle follows a given trajectory and / or maintains safe lateral and longitudinal distances between the autonomous vehicle and objects near the autonomous vehicle (e.g., cars in adjacent lanes on the road).

[0083] Vehicle 200 may be a car, truck, motorcycle, bus, boat, airplane, helicopter, lawn mower, recreational vehicle, playground vehicle, construction equipment, trolley, golf cart, train, push cart, etc. This is not particularly limiting in this embodiment of the present application.

[0084] Hereinafter, embodiments of the present application will be further described in detail with reference to the accompanying drawings.

[0085] It should be noted that in the embodiments of the present application, "plurality" means two or more. In addition, in the description of the present application, terms such as "first" and "second" are used merely for differentiation and explanation, and should not be understood as indicating or implying relative importance or as indicating or implying order. "Coupling" in the present application refers to electrical connection, and specifically may include two ways, namely, direct connection or indirect connection. The application scenarios of the embodiments of the present application are briefly described below.

[0086] 3 shows a signal transmission method according to an embodiment of the present application. The method is applied to a MIMO radar. The MIMO radar includes a transmitter, and the transmitter includes multiple transmitting antennas. Specifically, the method shown in FIG. 3 includes the following steps:

[0087] S301: A transmitter transmits a first burst in a first measurement frame.

[0088] The first measurement frame is used to measure the velocity of the target, and when the first burst is transmitted, each of the multiple transmit antennas transmits a chirp signal in a time-division multiplexed manner.

[0089] S302: The transmitter transmits a second burst in the first measurement frame after the transmitter transmits a first burst in the first measurement frame.

[0090] When the second burst is transmitted, the number of transmit antennas configured to transmit chirp signals is 1. In a real signal, the duration of a single chirp signal includes a sweep time (i.e., an effective measurement time) and an idle time (e.g., a phase-locked loop stabilization time or an analog-to-digital converter stabilization time).

[0091] The first measurement frame may be a frequency modulated continuous wave (FMCW). Of course, the first measurement frame may alternatively use a waveform used by another MIMO radar, such as multiple frequency-shift keying (MFSK) or phase modulated continuous wave (PMCW). This is not a limitation in this application.

[0092] It should be understood that the first transmitting antenna in this embodiment of the present application does not necessarily have to be the transmitting antenna with physical sequence number 1, and the first transmitting antenna may be any one of the multiple transmitting antennas.

[0093] In this embodiment of the present application, in the first burst, each transmitting antenna transmits a chirp signal in a time division manner, i.e., each transmitting antenna transmits a chirp signal. In the second burst, only one transmitting antenna transmits a chirp signal, which is referred to as the first transmitting antenna in this embodiment of the present application. The first burst may be considered to be transmitted in a MIMO manner, and the second burst may be considered to be transmitted in a SIMO manner.

[0094] For example, assume that the transmitter includes Nt transmit antennas, identified by 1, 2, 3, ..., Nt-2, Nt-1, and Nt, respectively. A specific example of a first measurement frame including a first burst (Burst 1) and a second burst (Burst 2) transmitted by the Nt transmit antennas may be shown in Figure 4. In the example of Figure 4, triangles represent chirp signals, and each chirp signal occupies a time slot. In Figure 4, for each chirp signal, the transmit antenna transmitting the chirp signal is represented by a number below the chirp signal. The first burst includes multiple chirp signals transmitted by the Nt transmit antennas in a time-division multiplexed manner. The second burst also includes multiple chirp signals transmitted only by the first transmit antenna.

[0095] All examples in this application are similar to the example in Figure 4, and strips are used to represent chirp signals, but it should be understood that the shape of the strips is only an example and does not represent the waveform of the chirp signal in actual applications. The specific waveform of the chirp signal is not limited in this embodiment of the application.

[0096] It should be noted that the order in which the Nt transmitting antennas transmit chirp signals in the first burst is not limited in this embodiment of the present application. For example, for Nt transmitting antennas 1, 2, 3, ... Nt-2, Nt-1, and Nt, the transmission order may be 1, 2, 3, ... Nt-2, Nt-1, and Nt, or the transmission order may not be arranged based on the numbers, such as 5, 8, 7, 10, ... Nt, Nt-2, Nt-1, etc. That is, in the first burst, the chirp signals may be transmitted sequentially based on the arrangement order of the transmitting antennas, or in a different order. Here, sequential transmission means that the antenna transmission order is consistent with the spatial proximity of the antennas in their physical arrangement, while transmitting in a different order means that the antenna transmission order is not consistent with the spatial proximity of the antennas in their physical arrangement.

[0097] It will be appreciated that since the first measurement frame includes a second burst transmitted in a SIMO manner, in this embodiment of the present application, a transmission overhead is introduced to solve the problem of coupling between velocity and angle in TDM MIMO radar.

[0098] Due to the complexity of the in-vehicle environment, the accuracy requirements of the target in the spatial dimensions (range, horizontal azimuth, and vertical azimuth) and the velocity dimensions may not be the same. Therefore, the waveform parameters of the first burst (e.g., the number of chirp signals included in the first burst, the transmission period of the transmit antennas, the time segment occupied by each transmit antenna, and the duration of each chirp signal) and the waveform parameters of the second burst (e.g., the number of chirp signals transmitted by the first transmit antenna, the duration of each chirp signal, etc.) may be dynamically configured based on the in-vehicle environment. Typically, the ECU configures the waveform parameters of the first burst and the second burst on the radar module using a common in-vehicle bus, such as a controller area network (CAN), a controller area network with flexible data-rate (CAN-FD), general Ethernet (GE), or other in-vehicle interface. The radar module can configure parameters on a monolithic microwave integrated circuit (MMIC) using a serial peripheral interface (SPI). When multiple chips are cascaded, the master and slave radio frequency front-end chips can be configured for flexible configuration. The MMIC can be configured to enable the transmitter to transmit the first measurement frame based on the aforementioned configuration.

[0099] It should be noted that when the vehicle interface configures the parameters on the radar module, the configured parameters are not limited to the above example, as long as the configured parameters are used to indicate how the transmitting antennas transmit chirp signals. For example, the configured parameters may be specific values ​​for the number of chirp signals included in the first burst and the second burst, the transmission period of the transmitting antennas, the time segments occupied by each transmitting antenna, and the duration of each chirp signal, or may be parameters equivalent to specific values ​​for the number of chirp signals included in the first burst, the transmission period of the transmitting antennas, the time segments occupied by each transmitting antenna, and the duration of each chirp signal.

[0100] It should also be noted that in this embodiment of the present application, a burst is a concept of a time segment, and a burst may also be called by other names such as a time slot, a subframe, or a frame. Additionally, in the description of the present application, a time slot is the smallest time unit, one burst includes at least one time slot, one subframe includes at least one burst, and one frame includes at least one subframe.

[0101] According to the above solution, target velocity range searching is performed using the echo signal formed after the first burst transmitted in the MIMO manner is reflected and the echo signal formed after the second burst transmitted in the SIMO manner after the first burst is reflected. By matching, velocity aliasing coefficients of one or more targets can be obtained, and the velocity measurement range of the MIMO radar can be restored to the velocity measurement range of the SIMO radar. In addition, the complexity of the MIMO spectrum peak search can be reduced, and the influence of channel phase noise on overlap can be reduced. In addition, since the strength of the echo signal is inversely proportional to the fourth power of the distance, when a SIMO burst (i.e., the second burst) is transmitted after a MIMO burst (i.e., the first burst), the fast-moving target can move closer within the SIMO burst. As a result, the problem of the weak echo signal of the fast-moving target within the SIMO burst can be alleviated to some extent.

[0102] The first burst may include N Doppler rounds of chirp signals, each round including M chirp signals, with the same transmission parameters, such as the transmission order, number of signals, and duration of the chirp signals across the multiple rounds.

[0103] In addition, in the first burst, the number of chirp signals transmitted by the transmitting antennas may be the same or different from each other.

[0104] For example, when transmitting the first burst, Nt transmit antennas 1, 2, 3, ..., Nt-2, Nt-1, and Nt transmit N Doppler rounds in the order of 1, 2, 3, ..., Nt-2, Nt-1, and Nt (e.g., N may be 32, 48, 64, 128, ...). Then, as shown in Figure 5, in the first burst, the number of chirp signals transmitted by each transmit antenna is N, that is, in the first burst, the number of chirp signals transmitted by the transmit antennas is the same. In the example of Figure 5, M = Nt.

[0105] For example, when transmitting the first burst, Nt transmit antennas 1, 2, 3, ..., Nt-2, Nt-1, and Nt transmit N Doppler rounds in the order of 1, 2, 3, ..., Nt-2, Nt-1, and Nt (for example, N may be 32, 48, 64, 128, ...), and then transmit antennas 1, 2, and 3 transmit three chirp signals. At that time, in the first burst, the number of chirp signals transmitted by transmit antennas numbered 1, 2, and 3 is greater than the number of chirp signals transmitted by other transmit antennas.

[0106] For example, when Nt transmit antennas 1, 2, 3, ..., Nt-2, Nt-1, and Nt transmit a first burst, the second transmit antenna further transmits chirp signals by interleaving them within the first burst simultaneously when each transmit antenna periodically transmits a chirp signal. When the second transmit antenna transmits chirp signals by interleaving them within the first burst, the second transmit antenna may transmit chirp signals periodically or aperiodically. The second transmit antenna and the first transmit antenna may be the same transmit antenna or different transmit antennas. Obviously, in the first burst, the number of chirp signals transmitted by the second transmit antenna is greater than the number of chirp signals transmitted by another transmit antenna.

[0107] According to the above solution, when the number of chirp signals transmitted by the transmitting antennas in the first burst is the same, the calculation process is relatively simple when the target velocity is calculated based on the echo signal formed after the first measurement frame is reflected.When the number of chirp signals transmitted by the transmitting antennas in the first burst is different from each other, the complexity of the spectrum peak search can be further reduced by using a high-density transmitting antenna.

[0108] Additionally, in this embodiment of the present application, before the transmitter performs S301 of transmitting the first burst in the first measurement frame, the method further includes the transmitter transmitting a third burst in the first measurement frame. When the third burst is transmitted, the number of transmit antennas configured to transmit chirp signals is 1, and the transmit antenna configured to transmit the third burst and the transmit antenna configured to transmit the second burst are the same transmit antenna (i.e., the first transmit antenna). The transmitter transmits the first measurement frame with a duty cycle of P%, P<100, where the duty cycle is equal to the ratio of the first duration to the second duration, the first duration is the duration of the first measurement frame, and the second duration is the time difference between two adjacent measurement frames transmitted by the transmitter.

[0109] Obviously, in the third burst, only the first transmit antenna transmits the chirp signal, that is, the third burst is transmitted in a SIMO manner.

[0110] For example, in the case of the first measurement frame shown in FIG. 4, when the first burst (Burst 1) is prefixed with the third burst (Burst 3), the first measurement frame shown in FIG. 4 changes to the form shown in FIG. 6.

[0111] The first measurement frame contains three bursts, with the first burst at the middle position being transmitted using MIMO, and the prefix and suffix of the first burst being transmitted using SIMO. Then, when the echo signal formed after the first measurement frame is reflected by one or more targets is processed, the two SIMO-transmitted bursts can be selected for velocity matching, simplifying target velocity calculation. This also alleviates the problem of the scattering center of a fast-moving target shifting over the transmission time to some extent.

[0112] In practical applications, the transmitter transmits the first measurement frame with a duty cycle of P%, P<100. That is, after the first measurement frame is transmitted, there is an idle time and processing time before the next measurement frame is transmitted. For this purpose, the duty cycle P% exists and P<100. In engineering, when P=100, the system power consumption is relatively high. Therefore, P<100 is commonly used.

[0113] For example, under the design constraint of a 20 Hz update period, each measurement frame cannot exceed 50 ms. Assume that the duration T1 of each chirp signal is 20 μs. In the first burst, each of the 12 transmit antennas transmits N doppler chirp signals, where N doppler = 64. The coherent processing interval (CPI) for the first burst is 20 * 64 * 12 = 15.36 ms. In addition, in the second burst, the first transmit antenna transmits M2 repetitively. For M2 = 192, the CPI for the second burst is 20 * 192 = 3.84 ms. Therefore, the duty cycle can be calculated as (15.36 + 3.84) / 50 = 38.4%. That is, during the measurement period, the time to transmit the chirp signal is 19.2 ms and the time for processing or idle time is 50-19.2=30.8 ms.

[0114] For example, when the first measurement frame transmitted by the transmitter has the form shown in FIG. 4, if the duty cycle P is less than 100, the transmitter can transmit three measurement frames as shown in FIG. 7. From FIG. 7, it can be seen that there is still processing and idle time after the first measurement frame is transmitted. During the processing or idle time, the radar system can process the echo signal formed after the first measurement frame is reflected by the target, or during the processing or idle time, no processing is performed and no chirp signal is transmitted.

[0115] Additionally, the method further includes, after the transmitter transmits the first measurement frame, transmitting a fourth burst in a second measurement frame. The second measurement frame is used to measure the velocity of a target, and when the fourth burst is transmitted, each of the multiple transmit antennas transmits a chirp signal in a time-division manner. After transmitting the fourth burst in the second measurement frame, the transmitter transmits a fifth burst in the second measurement frame. When the fifth burst is transmitted, the number of transmit antennas configured to transmit chirp signals is one, and the transmission parameters of the fifth burst, the second burst, and the third burst are the same. Specifically, the transmission parameters include a transmission slope, a transmit antenna, the number of transmitted chirp signals, the duration of each chirp signal, etc.

[0116] If the transmission parameters of the fifth burst, the second burst, and the third burst are the same, when calculating the velocity of the target, the second burst in the first measurement frame can be regarded as a SIMO prefix in the second measurement frame to reduce transmission overhead.

[0117] For example, as shown in FIG. 8, the first measurement frame (Frame 0) transmitted by the transmitter includes three bursts: Burst 3 (corresponding to the third burst), Burst 1 (corresponding to the first burst), and Burst 2 (corresponding to the second burst), with Burst 3 and Burst 2 having the same transmission parameters. In this case, the second measurement frame (Frame 1) may include only Burst 1 (corresponding to the fourth burst) and Burst 2 (corresponding to the fifth burst). When calculating the target velocity, Burst 2 in the first measurement frame can be regarded as the SIMO prefix in the second measurement frame. Similarly, the third measurement frame (Frame 2) also includes only Burst 1 and Burst 2, and reuses Burst 2 from the second measurement frame.

[0118] In conclusion, according to the signal transmission method provided in this embodiment of the present application, a first burst transmitted in a MIMO manner is prefixed with a second burst transmitted in a SIMO manner, and a target velocity range search can be performed based on the echo signal formed after the first burst is reflected and the echo signal formed after the second burst is reflected, to obtain one or more target velocity aliasing coefficients by matching, and return the velocity measurement range of the MIMO radar to the velocity measurement range of the SIMO radar.

[0119] Corresponding to the signal transmission method shown in FIG. 3 , an embodiment of the present application further provides a signal processing method for processing echo signals formed after the transmitted measurement frames are reflected by one or more targets to obtain the velocities of the one or more targets and to obtain the azimuth angles (e.g., horizontal azimuth angle and vertical azimuth angle) of the one or more targets.

[0120] The method is applied to a MIMO radar, which includes a transmitter, a receiver, and a processing unit, where the transmitter includes multiple transmitting antennas and the receiver includes multiple receiving antennas. See Figure 9. The method includes the following steps:

[0121] S901. A receiver receives a first echo signal and a second echo signal.

[0122] The first echo signal is formed after a first burst in a measurement frame transmitted by the transmitter is reflected by one or more targets, and the second echo signal is formed after a second burst in the measurement frame is reflected by one or more targets, the second burst being transmitted after the first burst. When the first burst is transmitted, each of the multiple transmit antennas transmits a chirp signal in a time-division manner. When the second burst is transmitted, the number of transmit antennas configured to transmit the chirp signal is one.

[0123] In S901, the echo signal received by the receiver is an echo signal formed after the first measurement frame transmitted by the transmitter in the manner shown in FIG. 3 is reflected by one or more targets.

[0124] It should be noted that in this embodiment of the present application, the receiver includes Nr receiving antennas, and the Nr receiving antennas receive Nt echo signals based on the transmission order of the Nt transmitting antennas. Then, the received echo signals are converted into first echo signals and second echo signals based on the positional relationship between the Nt transmitting antennas and the Nr receiving antennas and the transmission order of the transmitting antennas.

[0125] S902: A processing unit determines the velocity of one or more targets based on the echo signals received by the receiver.

[0126] Specifically, in S902, the processing unit determining the velocity of one or more targets based on the echo signals received by the receiver may be implemented by the processing unit determining a first identifier based on a first echo signal. The first identifier is used to indicate the distance measurement and the velocity measurement of the one or more targets. The processing unit determines a second identifier based on a second echo signal. The second identifier is used to indicate the distance measurement and the velocity measurement of the one or more targets. The processing unit determines the velocity of the one or more targets based on the first identifier and the second identifier.

[0127] The first identifier may include a first velocity identifier and a first distance identifier, and the second identifier may include a second velocity identifier and a second distance identifier. After the first echo signal is acquired, a range-Doppler map (RD map) may be obtained by performing operations such as one-dimensional FFT (1D-FFT), two-dimensional FFT (2D-FFT), and coherent / non-coherent combining, and then a first velocity identifier (Vind_MIMO) and a first distance identifier (Rind_MIMO) within the maximum velocity measurement range of MIMO are obtained by detection based on the RD map. Similarly, after the second echo signal is acquired, another RD map may be obtained by performing operations such as 1D-FFT, 2D-FFT, and coherent / non-coherent combining, and then a second velocity identifier (Vind_SIMO) and a second distance identifier (Rind_SIMO) within the maximum velocity measurement range of SIMO are obtained by detection based on the RD map.

[0128] Specifically, when detecting based on the RD map, there can be multiple detection methods, including but not limited to common detection methods such as ordered statistic-constant false alarm rate (OS-CFAR) detection or cell-averaging constant false alarm rate (CA-CFAR) detection, which is not particularly limited in this embodiment of the present application.

[0129] Additionally, because the SIMO burst (i.e., the second burst) and the MIMO burst (i.e., the first burst) may have different durations and transmit powers, the CFAR thresholds used for the first and second bursts may be different. For example, a relatively low threshold may be used for the SIMO burst and a relatively high threshold may be used for the MIMO burst to ensure that for each target detected in the MIMO burst, a point can be found that is relatively consistent in distance from the target detected in the SIMO burst for rate extension.

[0130] The first and second identifiers obtained in the above manner are only used to indicate the possible distance and velocity of the target, and there is target velocity aliasing. The first and second identifiers need to be further processed to determine the target velocity.

[0131] Specifically, the processing unit's determining the velocity of one or more targets based on the first identifier and the second identifier may be implemented in a manner in which the processing unit determines an aliasing coefficient interval corresponding to the first identifier based on a transmission repetition period of the first transmit antenna in the first burst. The processing unit determines an aliasing coefficient subset based on the first identifier, the second identifier, and the aliasing coefficient interval. The processing unit determines a velocity aliasing coefficient based on the aliasing coefficient subset. The processing unit determines the velocity of the one or more targets based on the velocity aliasing coefficient and the first identifier.

[0132] Each of the above steps will now be described in detail.

[0133] 1. Determine the aliasing coefficient interval corresponding to the first identifier

[0134] Assume that the first burst contains N Doppler rounds of chirp signals, each round containing M chirp signals, where the aliasing coefficient interval is [-M / 2, M / 2-1] if M is even, and [-M-1 / 2, M-1 / 2] if M is odd.

[0135] For example, if M=15, the aliasing coefficient interval is [-7, -6, -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7]. For example, if M=12, the aliasing coefficient interval is [-6, -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5].

[0136] 2. Determine an aliasing coefficient subset based on the first identifier, the second identifier, and the aliasing coefficient interval.

[0137] The speed measurement range in the SIMO burst is M times that in the MIMO burst. Therefore, if there is only one target at the same distance in the two bursts, the aliasing coefficient interval corresponding to the MIMO can be accurately obtained. If there are multiple targets within the distance interval, the elements in the aliasing coefficient interval can be obtained by matching based on the second speed identifier of the SIMO burst. After matching multiple targets, a union set can be obtained from the matched elements, and only the non-repeated parts can be retained to form an aliasing coefficient subset.

[0138] For example, assuming that the SIMO burst and the MIMO burst have a distance resolution of 0.1 m and the distance measurement range is 51.2 m, the RD map is divided into 512 distance cells (RD cells). The velocity identifiers of the detected targets in the SIMO burst and the MIMO burst within a certain threshold are obtained in distance units. If the transmission time of the SIMO burst is four times that of the MIMO burst, the velocity resolution of the SIMO burst is four times that of the MIMO burst. In this case, each cell in the velocity dimension of the SIMO burst is equivalent to four cells in the velocity dimension of the MIMO burst. Additionally, if the velocity resolution of the MIMO burst is dv_MIMO, the velocity resolution of the SIMO burst is 4*dv_MIMO. When M=12, the velocity measurement range is Vmax_SIMO=12*Vmax_MIMO, and the entire velocity measurement range of the SIMO is divided into 3*Vin_max_MIMO cells. That is, the value range of Vind_SIMO is 0 to 3*Vind_max_MIMO-1. The rate resolution in the MIMO burst is dv_MIMO, the rate measurement range is Vmax_MIMO, and the entire MIMO rate measurement range is divided into Vind_max_MIMO cells. That is, the value range of Vind_MIMO is 0 to Vind_max_MIMO-1. The second rate identifier obtained in SIMO can be converted to the corresponding aliasing coefficient interval of MIMO by using the formula floor(4*Vind_SIMO / Vind_max_MIMO) to obtain an element within the aliasing coefficient interval. For example, floor(4*Vind_SIMO / Vind_max_MIMO)=0 corresponds to the first element, -6, of [-6, -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5]. After the above operations are performed for each target, all the obtained elements may be combined and repeated elements may be removed to obtain an aliasing coefficient subset.

[0139] Obviously, an aliasing coefficient subset is a subset of the aliasing coefficient interval.

[0140] In addition, after the RD map is obtained by implementing the aforementioned solution, compensation can be further performed on the echo signals received by the receiving antennas based on (Rind_MIMO, Vind_MIMO) and the order in which the transmitting antennas transmit chirp signals in the first burst.

[0141] For example, based on the phase of the echo signal of the receive antenna corresponding to the transmit antenna in each time slot, the following equation can be obtained:

number

[0142]

number

number

number

number

number

[0143] Therefore, there are several ways to determine the aliasing coefficient subset S based on the first and second identifiers, two of which are listed below.

[0144] Method 1 A subset of aliasing coefficients for the entire scenario is calculated based on the Rind_SIMO and Vind_SIMO of all target points.

[0145] Specifically, based on the chirp signal transmission parameters of the first burst and the second burst, Vind_SIMO aliasing coefficients detected in the second burst corresponding to those of the first burst are calculated.

[0146] For example, in the first burst, G*Nt is the round of chirp signals (Nt is the number of transmit antennas, G is the number of chirp signals transmitted by each transmit antenna in one round, and the first burst can include multiple rounds of chirp signals), and in the round of chirp signals, N burst1_doppler chirp signals are transmitted in total (or N burst1_doppler (N chirps are transmitted after being padded with zeros). In the second burst, N burst2_doppler chirp signals are transmitted in total (or N burst2_doppler(The chirp signals are transmitted after adding zeros). The repetition period of the transmit antenna in the first burst is Tc_MIMO, and the repetition period of the transmit antenna in the second burst is Tc_SIMO. Assuming that Tc_MIMO=G*Nt*Tc_SIMO, the speed measurement range of the second burst is G*Nt times the speed measurement range of the first burst. That is, Vind_SIMO is G*Nt*Vmax_MIMO interval multiplied by N burst2_doppler This is equivalent to dividing the network into cells, and Vind_MIMO divides the Vmax_MIMO interval into N burst1_doppler Then, for each Vind_SIMO in the second identifier, find the value that is within the aliasing coefficient interval and is less than floor(Vind_SIMO / (N burst2_doppler / G*Nt)) can be obtained. Therefore, for each detected Vind_SIMO, the corresponding element in the aliasing coefficient interval can be obtained by solving, and a combined set is obtained based on all elements, and repeated elements are removed to obtain the aliasing coefficient subset S.

[0147] In Scheme 1, it is not necessary to obtain the aliasing coefficient subset for each target, but instead all detected Rind_SIMO and Vind_SIMO are processed together. However, for complex environments and large amounts of targets, the search and computation workload in Scheme 1 is relatively large.

[0148] Method 2 Since the distance of the target is not aliased, the distance reflected by Rind_SIMO and Rind_MIMO is generally real. At this time, for the same target, abs(Rind_SIMO-Rind_MIMO) is generally less than a threshold, and then an aliasing coefficient subset is calculated for each target. The specific calculation process is the same as in Method 1, and the details will not be repeated here.

[0149] Specifically, the specific value of the threshold can be adaptively adjusted based on parameters such as the second speed identifier and the length of the first burst. For example, assume that the transmission center times of the first burst and the second burst are separated by Tgap, and for Rind_SIMO acquired in the second burst, the existence of the time difference Tgap allows a target with a speed V to move K range cells (on the RD map) within the time Tgap. Then, the threshold can be determined based on the second speed identifier acquired in the second burst and an aliasing coefficient subset whose range unit perimeter is less than K range cells in the first burst.

[0150] In Scheme 2, aliasing coefficient subsets are resolved on each range cell to perform finer velocity matching, however the computational complexity of threshold comparison is introduced into the calculation.

[0151] 3. Determine the velocity aliasing coefficient based on the aliasing coefficient subset

[0152] After the aliasing coefficient subset is determined, the velocity aliasing coefficients may be determined in two ways.

[0153] Method 1: Overlap method The scheme in which two transmitting antennas at overlapping physical locations transmit chirp signals in two adjacent time slots is sometimes called overlapping. The phase difference between the receiving antennas corresponding to two or more adjacent time slots at the overlapping moment is determined only by the Doppler phase caused by the target velocity. Therefore, the corresponding velocity aliasing coefficient can be directly obtained by matching using the target velocity identifier calculated on the two transmitting antennas at overlapping physical locations.

[0154] In this embodiment of the present application, an overlap may be established in the process of transmitting the first burst and the second burst to resolve the rate aliasing coefficient subset.

[0155] Here, there may be several specific methods for calculating the velocity aliasing coefficient. The method may include the steps of: performing conjugate multiplication on corresponding received echo data in an aliasing coefficient subset of a soft overlap pair (two adjacent signals forming a pair) after Doppler phase compensation and the original overlap signal; performing addition on the multiple received signals; and finding the aliasing coefficient corresponding to the minimum value among the multiple aliasing coefficients included in the aliasing coefficient subset as the velocity aliasing coefficient. Alternatively, the velocity aliasing coefficient may be calculated by directly averaging the phase differences of multiple soft overlap pairs.

[0156] Method 2: Angular spectrum peak search method After the aliasing coefficient subset is determined, values ​​on different angular spectra of the received signal of the subarray corresponding to different elements in the aliasing coefficient subset S can be calculated, and the element in the aliasing coefficient subset S that corresponds to the maximum value of the angular spectrum is used as the velocity aliasing coefficient.

[0157] In practical applications, the transmitting antenna is configured to transmit a measurement frame, and the receiving antenna is configured to receive an echo signal formed after the measurement frame is reflected by a target. The antenna array may be virtualized into a virtual array including multiple virtual transmit and receive channels. The processing unit can convert the received echo signal into an observation result of the virtual array and perform processing and calculations based on the observation result of the virtual array to obtain information such as the range, velocity, and azimuth of the target.

[0158] Once the positions of the transmit and receive antenna arrays are determined, the position of the virtual array can be uniquely determined. Let Pm be the coordinate of antenna m (where m = 0, 1, ..., Ntx-1) among the Ntx transmit antennas, and Qn be the coordinate position of antenna n (n = 0, 1, ..., Nrx-1) among the Nrx receive antennas. The position of the array element in the formed virtual antenna array can be uniquely determined by Pm + Qn. After m traverses the Ntx transmit antennas and n traverses the Nrx receive antennas, the position of the virtual antenna array can be determined. Mathematically, the combined virtual array is Avirtual = kron(At, Ar), where At and Ar are the transmit and receive antenna arrays, respectively.

[0159] In Method 2, in the process of calculating the angular spectrum, FFT or digital beamforming (DBF) is performed based on the observation results of the virtual array.

[0160] If the virtual array is a uniform array, the FFT calculation can be accelerated. However, in practical applications, if the virtual array is a uniform array or a non-uniform array with a relatively large number of array elements, a virtual MIMO subarray of the uniform array can be constructed, and an FFT is performed on the observation results of the virtual MIMO subarray to calculate the angular spectrum. All array elements in the virtual MIMO subarray are equally spaced, and each transmit antenna corresponds to the same number of virtual array elements in the virtual MIMO subarray.

[0161] In one possible example, the processing unit's determining velocity aliasing coefficients based on the aliasing coefficient subset includes the processing unit determining observations of a virtual MIMO subarray based on echo signals received by the receiver. The processing unit determines the velocity aliasing coefficients based on the observations of the virtual MIMO subarray. The virtual MIMO subarray is a uniform planar or linear subarray including virtual array elements in the virtual array, where each transmit antenna corresponds to the same number of virtual array elements in the virtual MIMO subarray, and the virtual array includes multiple transmit antennas and multiple receive antennas included in the receiver.

[0162] For example, the positions of transmit antennas T1, T2, T3, and T4 and receive antennas R1, R2, R3, and R4, and the formed virtual array may be shown in Figure 10. Then, four array elements are selected from the virtual array to form a virtual MIMO subarray (the virtual array formed by the transmit antenna array and the receive antenna array has two empty positions, and the subarray extraction avoids two non-uniform subarrays), and an FFT is performed on the observations of the virtual MIMO subarray to calculate the angular spectrum.

[0163] For example, the positions of the transmit and receive antennas may be shown in Figure 11, and the formed virtual array may be shown in Figure 12. Then, 16 array elements are selected from the virtual array to form a virtual MIMO subarray, and an FFT is performed on the observations of the virtual MIMO subarray to calculate the angular spectrum.

[0164] In one possible example, the processing unit's determining velocity aliasing coefficients based on the aliasing coefficient subset includes the processing unit determining observations of a virtual MIMO subarray based on echo signals received by the receiver. The processing unit determines the velocity aliasing coefficients based on the observations of the virtual MIMO subarray. The virtual MIMO subarray is a uniform planar subarray or a uniform linear subarray including virtual array elements in the virtual array, the uniform planar subarray and the uniform linear subarray being obtained by linear interpolation, each transmit antenna corresponds to the same number of virtual array elements in the virtual MIMO subarray, and the virtual array includes multiple transmit antennas and multiple receive antennas included in the receiver.

[0165] That is, if a virtual MIMO subarray that satisfies the conditions (i.e., all array elements in the MIMO subarray are equally spaced and each transmit antenna corresponds to the same number of virtual array elements in the virtual MIMO subarray) cannot be found in the virtual array, the virtual MIMO subarray may be formed by linear interpolation.

[0166] For example, the positions of transmit antennas T1, T2, T3, and T4 and receive antennas R1, R2, R3, and R4, and the resulting virtual array are shown in FIG. 13. Obviously, it is impossible to find a satisfying virtual MIMO subarray within the virtual array (R1,3 and R4,2 marked with solid lines cannot form a subarray with R2,4 and R3,1). In this case, the corresponding array elements can be found by interpolation to form the virtual MIMO subarray, and the angular spectrum can be calculated. The observation results of the interpolated points can be obtained by, for example, calculating the average value.

[0167] After the velocity aliasing coefficient is determined, the processing unit can determine the velocity of one or more targets based on the velocity aliasing coefficient and the first identifier. For specific methods, please refer to the description of the prior art, and details will not be described here.

[0168] Furthermore, the method shown in FIG. 9 may further include the receiver receiving a third echo signal. The third echo signal is formed after a third burst in the measurement frame is reflected by one or more targets, and the third burst is transmitted before the first burst. At this time, the processing unit may determine the velocity of the one or more targets based on the echo signals received by the receiver. Specifically, if the one or more targets move away from the radar system, the processing unit may determine the velocity of the one or more targets based on the first echo signal and the third echo signal. If the one or more targets move toward the radar system, the processing unit may determine the velocity of the one or more targets based on the first echo signal and the second echo signal.

[0169] In other words, the prefix (third burst) is used to match receding targets, and the suffix (second burst) is used to match approaching targets.

[0170] Because the target actually moves within the three bursts, for distant targets, such movement affects the strength of the received signal from the target. As the target moves farther away, the distance to the target in the second burst increases, the signal strength from the target decreases, and the data in the third burst becomes more reliable. As the target moves closer, the distance to the target in the second burst decreases, the signal strength from the target increases, and the data in the second burst becomes more reliable.

[0171] The specific method for determining the velocity of one or more targets based on the first echo signal and the third echo signal may be the above-mentioned embodiment for determining the velocity of one or more targets based on the first echo signal and the second echo signal, and the details will not be repeated here.

[0172] In addition, if the measurement frame transmitted by the transmitter includes three bursts, the processing unit can further perform clustering and tracking based on target points that have consistent data measured in the second and third bursts, which are two bursts transmitted in a SIMO manner.

[0173] The reason for using SIMO for clustering and tracking is that processing real data shows that the relative high velocity points are determined inconsistently between SIMO and MIMO bursts, which is caused by micro-Doppler and target multipath.

[0174] Some micro-Doppler features of a target cause a mismatch between the target's macro velocity and micro velocity. For example, the speed of a wheel is different from the speed of a vehicle body, and the speed of a person's arm is different from the speed of the human body. In multipath reflections, both the measured distance and speed of the target are greater than the target's actual distance and speed. As a result, the velocity results of SIMO burst and MIMO burst are significantly different. Therefore, target points with consistent data can be used for clustering and tracking to obtain the correct macro velocity of the target and predict the target's motion state based on the macro velocity.

[0175] In conclusion, according to the signal processing method shown in FIG. 9, the echo signal formed after the first burst transmitted in the MIMO manner is reflected and the echo signal formed after the second burst transmitted in the SIMO manner after the first burst is reflected are used to obtain the velocity aliasing coefficients of one or more targets by matching, and the velocity measurement range of the MIMO radar can be restored to the velocity measurement range of the SIMO radar.

[0176] An embodiment of the present application provides a signal transmitting device, which may be configured to perform the signal transmitting method shown in Figure 3. Referring to Figure 14, the signal transmitting device includes a transmitter 1401.

[0177] The transmitter 1401 includes a plurality of transmit antennas, and is configured to: transmit a first burst in a first measurement frame, the first measurement frame being used to measure the velocity of a target, and when the first burst is transmitted, each of the plurality of transmit antennas transmits a chirp signal in a time-division manner; and transmit a second burst in the first measurement frame after transmitting the first burst in the first measurement frame, the number of transmit antennas configured to transmit the chirp signal being one when the second burst is transmitted.

[0178] Optionally, the transmitter 1401 is further configured to transmit a third burst in the first measurement frame before transmitting the first burst in the first measurement frame. When the third burst is transmitted, the number of transmit antennas configured to transmit chirp signals is 1, and the transmit antenna configured to transmit the third burst and the transmit antenna configured to transmit the second burst are the same transmit antenna. The transmitter 1401 transmits the first measurement frame with a duty cycle of P%, P<100, where the duty cycle is equal to a ratio of the first duration to the second duration, the first duration is the duration of the first measurement frame, and the second duration is the time difference between two adjacent measurement frames transmitted by the transmitter 1401.

[0179] Optionally, the transmitter 1401 is further configured to transmit a fourth burst in a second measurement frame after transmitting the first measurement frame, the second measurement frame being used to measure the velocity of the target, and when the fourth burst is transmitted, each of the multiple transmitting antennas transmits a chirp signal in a time-division manner, the transmitter 1401 is configured to transmit a fifth burst in the second measurement frame after transmitting the fourth burst in the second measurement frame, and when the fifth burst is transmitted, the number of transmitting antennas configured to transmit the chirp signal is 1, and the transmission parameters of the fifth burst, the second burst, and the third burst are the same.

[0180] The transmission parameters include one or more of a transmission slope, a transmission antenna, a number of transmitted chirp signals, or a duration of each chirp signal.

[0181] Optionally, the first measurement frame is one of FMCW, MFSK, or PMCW.

[0182] Optionally, in the first burst, the number of chirp signals transmitted by the multiple transmit antennas is different from each other.

[0183] Optionally, the signal transmitting apparatus 1400 further includes a processing unit 1402 configured to determine a configuration of the first measurement frame and to transmit the configuration of the first measurement frame to a monolithic microwave integrated circuit (MMIC) using the interface, wherein the MMIC is configured to enable the transmitter to transmit the first measurement frame based on the configuration of the first measurement frame.

[0184] It should be noted that the signal transmitting device 1400 shown in Fig. 14 may be configured to perform the signal transmitting method shown in Fig. 3. For implementation forms not described in detail in the signal transmitting device 1400, please refer to the relevant description of the signal transmitting method shown in Fig. 3.

[0185] An embodiment of the present application provides a signal processing device, which may be configured to perform the signal processing method shown in Fig. 9. Referring to Fig. 15, a signal transmitting device 1500 includes a receiver 1501 and a processing unit 1502.

[0186] The receiver 1501 is configured to receive a first echo signal and a second echo signal. The first echo signal is formed after a first burst in a measurement frame transmitted by the transmitter is reflected by one or more targets, and the second echo signal is formed after a second burst in the measurement frame is reflected by one or more targets, the second burst being transmitted after the first burst. When the first burst is transmitted, each of the multiple transmit antennas transmits a chirp signal in a time-division manner. When the second burst is transmitted, the number of transmit antennas configured to transmit the chirp signal is one.

[0187] The processing unit 1502 is configured to determine the velocity of one or more targets based on the echo signals received by the receiver 1501 .

[0188] Optionally, when determining the velocity of one or more targets based on the echo signals received by the receiver 1501, the processing unit 1502 is specifically configured to: determine a first identifier based on the first echo signal, where the first identifier is used to indicate distance and velocity measurements of the one or more targets; determine a second identifier based on the second echo signal, where the second identifier is used to indicate distance and velocity measurements of the one or more targets; and determine the velocity of the one or more targets based on the first identifier and the second identifier.

[0189] Optionally, when determining the velocity of one or more targets based on the first identifier and the second identifier, the processing unit 1502 is specifically configured to: determine an aliasing coefficient interval corresponding to the first identifier based on a transmission repetition period of the first transmitting antenna in the first burst; determine an aliasing coefficient subset based on the first identifier, the second identifier, and the aliasing coefficient interval; determine a velocity aliasing coefficient based on the aliasing coefficient subset; and determine the velocity of the one or more targets based on the velocity aliasing coefficient and the first identifier.

[0190] Optionally, receiver 1501 is further configured to receive a third echo signal. The third echo signal is formed after a third burst in the measurement frame is reflected by one or more targets, the third burst being transmitted before the first burst. When determining the velocity of the one or more targets based on the echo signals received by receiver 1501, processing unit 1502 is specifically configured to: determine the velocity of the one or more targets based on the first echo signal and the third echo signal if the one or more targets move away from the radar system; and determine the velocity of the one or more targets based on the first echo signal and the second echo signal if the one or more targets move toward the radar system.

[0191] Optionally, when determining velocity aliasing coefficients based on the aliasing coefficient subset, the processing unit 1502 is specifically configured to determine observation results of a virtual MIMO subarray based on echo signals received by the receiver 1501, and determine the velocity aliasing coefficients based on the observation results of the virtual MIMO subarray. The virtual MIMO subarray is a uniform planar subarray or a uniform linear subarray including virtual array elements in the virtual array, where each transmit antenna corresponds to the same number of virtual array elements in the virtual MIMO subarray, and the virtual array includes multiple transmit antennas and multiple receive antennas included in the receiver 1501.

[0192] Optionally, when determining velocity aliasing coefficients based on the aliasing coefficient subset, the processing unit 1502 is specifically configured to determine observation results of a virtual MIMO subarray based on echo signals received by the receiver 1501, and determine the velocity aliasing coefficients based on the observation results of the virtual MIMO subarray. The virtual MIMO subarray is a uniform planar subarray or a uniform linear subarray including virtual array elements in the virtual array, the uniform planar subarray and the uniform linear subarray are obtained by linear interpolation, each transmit antenna corresponds to the same number of virtual array elements in the virtual MIMO subarray, and the virtual array includes multiple transmit antennas and multiple receive antennas included in the receiver 1501.

[0193] It should be noted that the signal processing device 1500 shown in Fig. 15 may be configured to perform the signal processing method shown in Fig. 9. For implementation forms not described in detail in the signal processing device 1500, please refer to the relevant description of the signal processing method shown in Fig. 3.

[0194] Based on the same inventive concept, an embodiment of the present application further provides a radar system. Referring to Figure 16, a radar system 1600 includes a transmitter 1601, a receiver 1602, and a processing unit 1603.

[0195] The transmitter 1601 includes a plurality of transmit antennas, and is configured to: transmit a first burst in a measurement frame, the measurement frame being used to measure the velocity of a target, and when the first burst is transmitted, each of the plurality of transmit antennas transmits a chirp signal in a time-division manner; and transmit a second burst in the measurement frame after transmitting the first burst, the number of transmit antennas configured to transmit the chirp signal being one when the second burst is transmitted.

[0196] The receiver 1602 is configured to receive a first echo signal and a second echo signal, the first echo signal being formed after the first burst is reflected by one or more targets, and the second echo signal being formed after the second burst is reflected by one or more targets.

[0197] The processing unit 1603 is configured to determine the velocity of one or more targets based on the echo signals received by the receiver 1602 .

[0198] Obviously, those skilled in the art can make various modifications and variations to the embodiments of the present application without departing from the scope of the embodiments of the present application. Thus, the present application is intended to cover these modifications and variations of the embodiments of the present application as long as they fall within the scope of protection defined by the following claims and their equivalent technologies. [Explanation of symbols]

[0199] 100 vehicles 101 Antenna Array 102 Monolithic Microwave Integrated Circuit 103 Processing Unit 142 Routing Control System 200 vehicles 202 Running System 204 Sensor System 206 Control System 208 Peripheral Devices 210 Power supply 212 Computer Systems 216 User Interface 218 Engine 219 Energy Sources 220 Transmission 221 Wheels and tires 222 Positioning System 223 processor 224 Memory, Inertial Measurement Unit 225 Command 226 Radar 228 Laser Range Finder 230 Camera 232 Steering system, steering unit 234 Axel 236 Brake unit 238 Sensor Fusion Algorithm, Sensor 240 Computer Vision System 242 Routing Control System 244 Obstacle Avoidance System 246 Wireless Communication Systems 248 In-Vehicle Computer 250 microphones 252 Speaker 1400 Signal Transmitter 1401 Transmitter 1402 Processing Unit 1500 Signal Processing Device 1501 Receiver 1502 Processing Unit 1600 Radar System 1601 Transmitter 1602 receiver 1603 Processing Unit

Claims

1. 1. A signal transmission method applied to a multiple-input multiple-output (MIMO) radar, the MIMO radar comprising a transmitter, the transmitter comprising a plurality of transmitting antennas; transmitting, by the transmitter, a first burst in a first measurement frame, the first measurement frame being used to measure a velocity of a target, and wherein when the first burst is transmitted, each of the plurality of transmit antennas transmits a chirp signal in a time-division multiplexed manner; transmitting, by the transmitter, a second burst in the first measurement frame immediately after the transmitter transmits the first burst in the first measurement frame, wherein when the second burst is transmitted, the number of transmit antennas configured to transmit chirp signals is one; Including, before the step of transmitting, by the transmitter, a first burst in a first measurement frame; transmitting, by the transmitter, a third burst in the first measurement frame immediately before transmitting the first burst in the first measurement frame, wherein when the third burst is transmitted, the number of transmit antennas configured to transmit chirp signals is one, and the transmit antenna configured to transmit the third burst and the transmit antenna configured to transmit the second burst are the same transmit antenna. The method further comprises:

2. After the transmitter transmits the first measurement frame, transmitting, by the transmitter, a fourth burst in a second measurement frame, the second measurement frame being used to measure the velocity of the target, and wherein when the fourth burst is transmitted, each of the plurality of transmit antennas transmits a chirp signal in the time-division multiplexed manner; transmitting, by the transmitter, a fifth burst in the second measurement frame after the transmitter has transmitted the fourth burst in the second measurement frame, wherein when the fifth burst is transmitted, the number of transmit antennas configured to transmit chirp signals is one, and transmission parameters of the fifth burst, the second burst, and the third burst are the same; The method of claim 1 further comprising:

3. 3. The method of claim 2, wherein the transmission parameters include one or more of a transmission slope, a transmission antenna, a number of transmitted chirp signals, or a duration of each chirp signal.

4. 4. The method of claim 1, wherein the first measurement frame is a frequency modulated continuous wave (FMCW) or a phase modulated continuous wave (PMCW).

5. The method according to claim 1 , wherein the number of chirp signals transmitted by the plurality of transmitting antennas in the first burst is different from each other.

6. the MIMO radar further comprises a processing unit; determining, by the processing unit, a configuration of the first measurement frame and transmitting, using an interface, the configuration of the first measurement frame to a monolithic microwave integrated circuit (MMIC), the MMIC configured to enable the transmitter to transmit the first measurement frame based on the configuration of the first measurement frame.

6. The method of claim 1, further comprising:

7. 1. A signal processing method applied to a multiple-input multiple-output (MIMO) radar, the MIMO radar comprising a transmitter, a receiver, and a processing unit, the transmitter comprising a plurality of transmitting antennas; receiving, by the receiver, a first echo signal and a second echo signal, wherein the first echo signal is formed after a first burst in a measurement frame transmitted by the transmitter is reflected by one or more targets, and the second echo signal is formed after a second burst in the measurement frame is reflected by the one or more targets, the second burst being transmitted immediately after the first burst, wherein when the first burst is transmitted, each of the plurality of transmitting antennas transmits a chirp signal in a time-division manner, and when the second burst is transmitted, the number of transmitting antennas configured to transmit a chirp signal is one; receiving, by the receiver, a third echo signal, the third echo signal being formed after a third burst in the measurement frame is reflected by the one or more targets, the third burst being transmitted immediately before the first burst; determining, by the processing unit, the velocity of the one or more targets based on the echo signals received by the receiver; A method comprising:

8. determining, by the processing unit, the velocity of the one or more targets based on echo signals received by the receiver, determining, by the processing unit, the velocity of the one or more targets based on the first echo signal and the third echo signal if the one or more targets move away from the radar system; determining, by the processing unit, the velocity of the one or more targets based on the first echo signal and the second echo signal if the one or more targets move closer to the radar system; 8. The method of claim 7, comprising:

9. A signal transmitting device, a transmitter comprising a plurality of transmit antennas; transmitting a first burst in a first measurement frame, the first measurement frame being used to measure a velocity of a target, and when the first burst is transmitted, each of the plurality of transmit antennas transmits a chirp signal in a time-division multiplexed manner; transmitting a second burst in the first measurement frame immediately after transmitting the first burst in the first measurement frame, wherein when the second burst is transmitted, the number of transmit antennas configured to transmit chirp signals is one; a transmitter configured to: Equipped with The transmitter transmitting a third burst in the first measurement frame immediately before transmitting the first burst in the first measurement frame, wherein when the third burst is transmitted, the number of transmit antennas configured to transmit chirp signals is one, and the transmit antenna configured to transmit the third burst and the transmit antenna configured to transmit the second burst are the same transmit antenna; The apparatus is further configured to:

10. The transmitter transmitting a fourth burst in a second measurement frame after transmitting the first measurement frame, the second measurement frame being used to measure the velocity of the target, and when the fourth burst is transmitted, each of the plurality of transmit antennas transmits a chirp signal in the time division manner; transmitting a fifth burst in the second measurement frame after transmitting the fourth burst in the second measurement frame, wherein when the fifth burst is transmitted, the number of transmit antennas configured to transmit chirp signals is one, and transmission parameters of the fifth burst, the second burst, and the third burst are the same; The apparatus of claim 9 , further configured to:

11. 11. The apparatus of claim 10, wherein the transmission parameters include one or more of a transmission slope, a transmission antenna, a number of transmitted chirp signals, or a duration of each chirp signal.

12. 12. The apparatus of claim 9, wherein the first measurement frame is a frequency modulated continuous wave (FMCW) or a phase modulated continuous wave (PMCW).

13. 13. The apparatus according to claim 9, wherein the number of chirp signals transmitted by the plurality of transmitting antennas in the first burst is different from each other.

14. a processing unit configured to determine a configuration of the first measurement frame and transmit the configuration of the first measurement frame to a monolithic microwave integrated circuit (MMIC) using an interface, the MMIC configured to enable the transmitter to transmit the first measurement frame based on the configuration of the first measurement frame.

14. The apparatus of claim 9, further comprising:

15. 1. A signal processing device, comprising: a receiver configured to receive a first echo signal and a second echo signal, wherein the first echo signal is formed after a first burst in a measurement frame transmitted by a transmitter is reflected by one or more targets, and the second echo signal is formed after a second burst in the measurement frame is reflected by the one or more targets, the second burst being transmitted immediately after the first burst, wherein when the first burst is transmitted, each of a plurality of transmitting antennas transmits a chirp signal in a time-division manner, and when the second burst is transmitted, the number of transmitting antennas configured to transmit a chirp signal is one; a processing unit configured to determine the velocity of the one or more targets based on echo signals received by the receiver; and Equipped with The receiver includes: receiving a third echo signal, the third echo signal being formed after a third burst in the measurement frame is reflected by the one or more targets, the third burst being transmitted immediately before the first burst; The apparatus is further configured to:

16. When determining the velocity of the one or more targets based on echo signals received by the receiver, the processing unit: determining the velocity of the one or more targets based on the first echo signal and the third echo signal when the one or more targets move away from the radar system; determining the velocity of the one or more targets based on the first echo signal and the second echo signal when the one or more targets move closer to the radar system; 16. The apparatus of claim 15, further configured to:

17. 1. A radar system comprising: a transmitter comprising a plurality of transmit antennas; transmitting a first burst in a measurement frame, the measurement frame being used to measure a velocity of a target, and when the first burst is transmitted, each of the plurality of transmit antennas transmits a chirp signal in a time-division multiplexed manner; transmitting a second burst in the measurement frame immediately after transmitting the first burst in the measurement frame, wherein when the second burst is transmitted, the number of transmit antennas configured to transmit chirp signals is one; a transmitter configured to: a receiver configured to receive a first echo signal and a second echo signal, the first echo signal being formed after the first burst is reflected by one or more targets, and the second echo signal being formed after the second burst is reflected by the one or more targets; a processing unit configured to determine the velocity of the one or more targets based on echo signals received by the receiver; and Equipped with The transmitter transmitting a third burst in the measurement frame immediately before transmitting the first burst in the measurement frame, wherein when the third burst is transmitted, the number of transmit antennas configured to transmit chirp signals is one, and the transmit antenna configured to transmit the third burst and the transmit antenna configured to transmit the second burst are the same transmit antenna; The radar system is further configured to:

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