Radar device and method of processing radar signal

Abstract

To improve the target detection probability of a radar signal transmitted according to a DDMA (Doppler Division Multiplex Access) method of a radar device.SOLUTION: A radar device includes: a plurality of transmitting antennas; a plurality of receiving antennas; and an MMIC (Monolithic Microwave Integrated Circuit) that controls the plurality of transmitting antennas and the plurality of receiving antennas. The MMIC transmits a radar signal by a DDMA method through the plurality of transmitting antennas, receives a reflected signal, which is at least a part of the radar signal reflected from a target through the plurality of receiving antennas, estimates a transmitting antenna corresponding to the reflected signal among the plurality of transmitting antennas on the basis of a phase corresponding to the received reflected signal, and sets so as to acquire radar data corresponding to the target on the basis of the estimated transmitting antenna and the reflected signal.SELECTED DRAWING: Figure 3a

Description

[Technical Field]

[0001] The present disclosure relates to a radar device and a method for processing a radar signal. [Background technology]

[0002] A radar system must have high angular resolution to detect or track the distance, speed, and angle of a target device through the transmission and reception of radio waves. Existing radar systems have used a structure in which multiple transmitting and receiving antennas are arranged to improve angular resolution.

[0003] FMCW (Frequency Modulated Continuous Wave) radar uses a transmit signal whose transmission frequency is modulated in a ramp pattern. This signal is transmitted continuously while the ramp is progressing. The FMCW radar generates a baseband signal by mixing the received signal with the transmitted signal. The frequency of the baseband signal corresponds to the frequency difference between the signal transmitted at a given time and the signal received at the same time. The frequency difference depends on the propagation time of the signal from the radar to the target or reflected from the target due to the frequency modulation of the transmitted signal, and also includes a component due to the relative velocity of the target due to the Doppler effect.

[0004] MIMO (Multi-Input Multi-Output) is widely used to expand the effective aperture size of a radar device by synthesizing a virtual receiver array through a combination of multiple physically implemented transmitter channels and multiple receiver channels. However, FMCW radar devices using MIMO have a problem in that it is difficult to distinguish signals transmitted from multiple transmitting antennas. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] US Patent Application Publication No. 2022 / 0334240 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present disclosure is to improve the target detection probability for radar signals transmitted in accordance with a Doppler Division Multiplex Access (DDMA) method of a radar device.

[0007] However, the technical problems that this embodiment aims to solve are not limited to the above-mentioned technical problems, and other technical problems may exist. [Means for solving the problem]

[0008] A radar device according to an embodiment of the present disclosure may include a plurality of transmitting antennas, a plurality of receiving antennas, and an MMIC (Monolithic Microwave Integrated Circuit) that controls the plurality of transmitting antennas and the plurality of receiving antennas, wherein the MMIC may be configured to transmit radar signals via the plurality of transmitting antennas using a Doppler Division Multiplex Access (DDMA) method, receive reflected signals formed by at least a portion of the radar signals being reflected from a target via the plurality of receiving antennas, estimate a transmitting antenna among the plurality of transmitting antennas that corresponds to the reflected signal based on a phase corresponding to the received reflected signal, and acquire radar data corresponding to the target based on the estimated transmitting antenna and the reflected signal.

[0009] A method for processing radar signals according to an embodiment of the present disclosure may include an operation of transmitting radar signals via a plurality of transmitting antennas using a Doppler Division Multiplex Access (DDMA) method; receiving, via a plurality of receiving antennas, reflected signals formed by at least some of the radar signals being reflected from a target; estimating, based on a phase corresponding to the received reflected signals, a transmitting antenna among the plurality of transmitting antennas that corresponds to the reflected signals; and acquiring radar data corresponding to the target based on the estimated transmitting antenna and the reflected signals. [Effects of the Invention]

[0010] According to one embodiment of the present disclosure, the physical transmit antennas can be divided in a radar device's DDMA (Doppler Division Multiplex Access) method, and the signal-to-noise ratio (SNR) for peaks can be improved by accumulating data for the transmit antennas.

[0011] Furthermore, according to an embodiment of the present disclosure, applying a uniform phase step in the Doppler axis direction can improve the target detection probability and reduce the amount of calculation required for data processing. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a configuration diagram of a radar device according to an embodiment of the present disclosure. [Figure 2] 1 is a time-frequency graph of a radar signal according to one embodiment of the present disclosure. [Figure 3a] 1 is a graph of a transmission signal of a Doppler division multiplexing access scheme according to an embodiment of the present disclosure. [Figure 3b] 10 is a graph of a transmission signal of a time division multiple access access method according to a comparative example of the present disclosure. [Figure 4a] 1 is a range-Doppler map of a reflected signal using a Doppler division multiplexing access scheme according to an embodiment of the present disclosure. [Figure 4b] 10 is a range-Doppler map of a reflected signal using a time division multiple access access method according to a comparative example of the present disclosure. [Figure 5a] 1 is a range-Doppler map (RD map) of a reflected signal corresponding to a transmitted signal using a uniform phase step according to an embodiment of the present disclosure. [Figure 5b] This is a part of Figure 5a. [Figure 5c] 10 is a range-Doppler map (RD map) of a reflected signal corresponding to a transmitted signal using Non-Uniform Phase Step according to a comparative example. [Figure 5d] This is a part of Figure 5c. [Figure 6a] 1 is a range-Doppler map (RD map) accumulating 2D FFT data of reflected signals according to one embodiment of the present disclosure. [Figure 6b] 6b is an illustration of a one-dimensional floating map of the range-Doppler map of FIG. 6a. [Figure 6c] 6b is an illustration of a one-dimensional floating map of the range-Doppler map of FIG. 6a. [Figure 7a] 1 illustrates a physical layout of multiple transmit antennas and multiple receive antennas according to one embodiment of the present disclosure. [Figure 7b] 1 is a virtual array of multiple transmit antennas and multiple receive antennas according to one embodiment of the present disclosure. [Figure 8a] 10 is a graph of a cost function as a function of angle according to one embodiment of the present disclosure. [Figure 8b] 1 is a range-Doppler map (RD map) for 2D FFT data of a reflected signal according to an embodiment of the present disclosure. [Figure 9] 1 is a range-Doppler map (RD map) for 2D FFT data of reflected signals accumulated at a transmitting antenna and a receiving antenna, respectively, according to an embodiment of the present disclosure. [Figure 10] 1 is a flowchart of a method for processing a radar signal according to one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present application will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present application. However, the present application may be embodied in various different forms and is not limited to the embodiments described herein. In the drawings, parts that are not relevant to the description are omitted for clarity, and similar parts are designated by similar reference numerals throughout the specification.

[0014] Throughout this specification, when a member is said to be "on" another member, this includes not only when the member is in contact with the other member, but also when there is another member between the two members.

[0015] Throughout this specification, when a part is said to "comprise" a certain element, this means that it may further include other elements, but not to the exclusion of other elements, unless otherwise specified.

[0016] As used throughout the specification of this application, terms of degree such as "about," "substantially," etc., are used to mean a numerical value or a approximation of a numerical value when manufacturing and material tolerances inherent in the recited meaning are given, and are used to prevent unscrupulous infringers from unfairly taking advantage of disclosures in which precise or absolute numerical values ​​are recited to aid in the understanding of this application. As used throughout the specification of this application, the terms "steps to" or "steps of" do not mean "steps for."

[0017] Throughout this specification, the term "combinations thereof" contained in a Markush phrase means a mixture or combination of one or more selected from the group of elements set forth in the Markush phrase, and is meant to include one or more selected from the group of elements.

[0018] Throughout the specification of this application, the phrase "A and / or B" means "A or B, or A and B."

[0019] Hereinafter, embodiments and examples of the present application will be described in detail with reference to the accompanying drawings, but the present application is not limited to these embodiments and examples and drawings.

[0020] FIG. 1 is a configuration diagram of a radar device 10 according to an embodiment of the present disclosure.

[0021] Referring to FIG. 1, a radar device 10 according to one embodiment may be configured to transmit and / or receive radar signals output from an MMIC (Monolithic Microwave Integrated Circuit) 100 via a transmitting antenna circuit 140 and / or a receiving antenna circuit 150.

[0022] In one embodiment, MMIC 100 may be configured to generate and transmit radar signals (e.g., transmit signals). In one embodiment, MMIC 100 may be configured to receive radar signals (e.g., reflected signals) from an external source. For example, radar signals may be at mm-wave frequencies or in a frequency band ranging from 3 MHz to 300 GHz in the electromagnetic spectrum.

[0023] In one embodiment, radar system 10 may transition or guide radar signals generated by MMIC 100 across multiple transmit antennas and / or may transition or guide radar signals received at multiple receive antennas across the MMIC.

[0024] In one embodiment, the radar system 10 is a multiple-input multiple-output (MIMO) radar, and may emulate a larger aperture phased array radar, for appropriate transmit antenna spacing. Such a larger array may be referred to as a virtual array.

[0025] In one embodiment, the MMIC 100 may be a microwave integrated circuit including a VCO 110, a PLL 120, a PA 130, a transmit antenna circuit 140, a receive antenna circuit 150, an LNA 160, a MIXER 170, an LPF 180, and / or an A / D 190.

[0026] The VCO (Voltage Controlled Oscillator) 110 is an oscillator that generates a variable frequency that is linearly proportional to an input control voltage, and by changing the input control voltage to control the output oscillation frequency, it may generate a sine wave whose frequency increases linearly with voltage.

[0027] The PLL (Phase Locked Loop) 120 is a circuit that synchronizes with the input frequency and phase on average while reducing phase fluctuations other than amplitude, and may also perform phase shift correction and frequency up conversion.

[0028] The phase rotator 125 may generate a phase change in the transmitted signal or the reflected signal. The phase rotator 125 may apply a phase shift of a predetermined magnitude to the transmitted signal transmitted through the transmitting antenna circuit 140.

[0029] The PA (Power Amplifier) ​​130 is a power amplifier capable of generating high output power and may amplify the radar signal. The transmit antenna circuit 140 may radiate the radar signal amplified by the PA 130 to the outside. In one embodiment, the transmit antenna circuit 140 may include multiple transmit antennas (e.g., 4Tx).

[0030] At least a portion of the radar signal transmitted via the transmit antenna circuit 140 may be reflected by a target, and the receive antenna circuit 150 may receive the reflected signal from the target. In one embodiment, the receive antenna circuit 150 may include multiple receive antennas (e.g., 4Rx).

[0031] The LNA (Low Noise Amplifier) ​​160 is a low noise amplifier designed to minimize noise so as to amplify a weak RF signal, and may perform amplification that minimizes noise and maximizes the signal.

[0032] The MIXER 170 may down-convert the frequency of the received radar signal by mixing the transmitted signal and the reflected signal.

[0033] The LPF (Low Pass Filter) 180 may pass only low frequency bands and filter high frequency bands. The A / D (Analog-to-Digital Converter) 190 may convert analog radar signals to digital types, allowing the MMIC 100 to extract beat frequencies containing range and velocity information from the received radar signals.

[0034] In one embodiment, the reflected signal from the target may be conjugate mixed with the transmitted signal to generate a low frequency beat signal (e.g., a baseband signal), whose frequency provides the range of the target. This operation may be repeated for P consecutive FMCW chirps.

[0035] In one embodiment, the range R to a target may be determined based on the round-trip time it takes for a radar signal to propagate to and from the target (R=cτ / 2, where τ is the round-trip time in seconds and c is the speed of light in meters per second). Estimating τ allows for range measurement.

[0036] FIG. 2 is a time-frequency graph of a radar signal according to one embodiment of the present disclosure. FIG. 3a is a graph of a transmitted signal using a Doppler division multiplexing access scheme according to one embodiment of the present disclosure. FIG. 3b is a graph of a transmitted signal using a time division multiplexing access scheme according to a comparative embodiment of the present disclosure. FIG. 4a is a range-Doppler map of a reflected signal using a Doppler division multiplexing access scheme according to one embodiment of the present disclosure. FIG. 4b is a range-Doppler map of a reflected signal using a time division multiplexing access scheme according to a comparative embodiment of the present disclosure.

[0037] Referring to Figures 2, 3a, 3b, 4a, and 4b, a radar device 10 (e.g., MMIC 100) according to one embodiment may transmit a transmission signal Tx via multiple transmission antennas Tx1, Tx2, Tx3, and Tx4, and receive a reflected signal Rx reflected from a target via multiple receiving antennas.

[0038] In one embodiment, the radar device 10 may be an FMCW (Frequency Modulation Continuation Wave) radar, transmitting a continuous wave (CW) signal that is frequency modulated over time. The CW signal may include periodic, short power pulses and silent periods. The silent periods allow the radar device 10 to receive reflected signals and serve as timing marks for the radar device 10 to perform range estimation. In a pulse radar configuration using CW pulses, simultaneous range-velocity estimation may be provided in multiple target traffic scenarios. The radar device 10 transmits periodic FM chirps (or pulses or ramps), the frequency of which may increase linearly during the pulse.

[0039] The radar device 10 according to one embodiment may control multiple transmit antennas Tx1, Tx2, Tx3, and Tx4 to phase the FMCW radar chirps in a sequence according to a predefined Doppler Division Multiplex Access (DDMA) scheme.

[0040] A radar device 10 according to one embodiment may transmit radar signals via multiple transmitting antennas Tx1, Tx2, Tx3, and Tx4 using a DDMA scheme. In one embodiment, the radar device 10 may simultaneously radiate radar signals via the multiple transmitting antennas Tx1, Tx2, Tx3, and Tx4, and the radar signals may include multiple chirps to which a phase shift of a predetermined magnitude is successively applied. According to the DDMA scheme, the radar signals may have different phases for each chirp, thereby generating a frequency shift in the Doppler frequency direction.

[0041] When transmitting radar signals using the DDMA method, the target velocity can be estimated unambiguously only by accurately identifying the transmitting antenna corresponding to the received reflected signal, and thus the target angle can be estimated accurately.

[0042] In the past, to distinguish between transmitting antennas, the first transmitting antenna was estimated by applying phase shift using non-uniform phase step, or the transmitting antenna was estimated using the empty band. However, when using non-uniform phase step, it was not possible to accurately detect targets when the signal-to-noise ratio was low, and the amount of calculation increased, requiring additional processing cores. In addition, when using the empty band, there was a problem that radar performance relative to the magnitude of the radar signal deteriorated, resulting in a lower signal-to-noise ratio.

[0043] In one embodiment, the multiple transmitting antennas Tx1, Tx2, Tx3, and Tx4 may simultaneously emit radar signals having different phase shifts, and the predetermined magnitude of the phase shift may be set differently for each of the multiple transmitting antennas Tx1, Tx2, Tx3, and Tx4, or may be maintained at a constant magnitude.

[0044] In one embodiment, the phase shifts preset for the multiple transmit antennas Tx1, Tx2, Tx3, and Tx4 are uniformly set by θ Step For example, a uniform phase shift of 0° step may be set for transmitting antenna Tx1, 90° step for transmitting antenna Tx2, 180° step for transmitting antenna Tx3, and 270° step for transmitting antenna Tx4.

[0045] The phase shift by the Uniform Phase Step in the multiple transmitting antennas Tx1, Tx2, Tx3, and Tx4 may be expressed by the following equation.

[0046]

number

[0047] Here, m is the transmit antenna index, and q is the chirp index. For example, Step ) may be the magnitude of the phase obtained by dividing 360 degrees by the number of transmitting antennas.

[0048] In one embodiment, the reflected signal by the Doppler division multiplexing access method of the radar device 10 may be expressed as follows: For example, the reflected signal below may be beat frequency data sampled by an ADC.

[0049]

number

[0050] In the above equation, the first component below may represent the phase shift of the signal, the second component below may represent the angle of the signal, the third component below may represent the range of the signal, and the fourth component below may represent the Doppler of the signal.

number

[0051] In contrast, the radar device 10 can radiate radar signals from multiple transmitting antennas Tx1, Tx2, Tx3, and Tx4 at different times using time division multiple access (TDMA), which prevents the radar signals from being radiated from the multiple transmitting antennas Tx1, Tx2, Tx3, and Tx4 at times that overlap each other.

[0052] The reflected signal by the time division multiple access (TDMA) method of the radar device 10 may be expressed as follows: For example, the reflected signal below may be beat frequency data sampled by an ADC.

[0053]

number

[0054] In the above equation, the first component may represent a unit square wave function of the signal, the second component may represent the angle of the signal, the third component may represent the range of the signal, and the fourth component may represent the Doppler of the signal.

number

[0055] Beat frequency (f b ) is the up-beat frequency (f bu = μ 2R / c) and Doppler frequency (f d = 2v / λ).

[0056] where t is the time (sample index), T c is the Pulse Repetition Interval (PRI), d t is the distance between the transmitting antennas, d r is the distance between the receiving antennas, e iφm,q is the phase shift, f s is the sampling frequency, v is the target speed, K is the number of targets, B is the bandwidth, T is the sweep time, μ is B / T, R is the range from the radar device 10 to the target, c is the speed of light in meters per second, λ is the wavelength of the radar signal, m is the transmitting antenna index, n is the receiving antenna index, and q is the chirp index.

[0057] The radar device 10 according to one embodiment may convert the received reflected signal into frequency components in the range-Doppler domain by applying a Fast Fourier Transform (FFT) to the received reflected signal.

[0058] In one embodiment, the radar device 10 may perform a 2D FFT on the reflected signal using the range axis (t axis) and the Doppler axis (q axis). bu (k) -f d (k) The frequency may be calculated, which is the same as the beat frequency. The radar device 10 performs a Doppler FFT to obtain f d (k) The frequency may be calculated, which is the same as the Doppler frequency. Thus, the radar device 10 can obtain components for the range and velocity of the target through the 2D FFT data for the reflected signal.

[0059] The radar device 10 according to one embodiment may obtain a range-Doppler map (RD map) based on 2D FFT data for the reflected signals of each receiving antenna.

[0060] In one embodiment, the radar device 10 may acquire a range-Doppler map (RD map) by performing non-coherent integration (NCI) on 2D FFT data for reflected signals received by each of the multiple receiving antennas. In one embodiment, the radar device 10 may acquire a range-Doppler map (RD map) by integrating (magnitude summation) the 2D FFT data.

[0061] For example, the 2D FFT data of the reflected signal by the Doppler Division Multiple Access (DDMA) method of the radar device 10 may be accumulated by the following formula:

[0062]

number

[0063] For example, the 2D FFT data of the reflected signal in the time division multiple access (TDMA) mode of the radar device 10 may be accumulated according to the following formula:

[0064]

number

[0065] Here, Tx is the number of transmitting antennas, Rx is the number of receiving antennas, q is the chirp index, and s is the range (sample) index.

[0066] For example, since reflected signals using a time division multiple access (TDMA) method receive data in time divisions, the positions of physical antennas corresponding to the reflected signals may be matched in the order in which they are received.

[0067] The range-Doppler map (RD map) of the reflected signal using the Doppler Division Multiple Access (DDMA) method shown in Figure 4a is different from the range-Doppler map (RD map) of the reflected signal using the Time Division Multiple Access (TDMA) method shown in Figure 4b in that transmitted signals with different phases are transmitted simultaneously, so the reflected signal received at one receiving antenna contains all transmitted signals from all transmitting antennas, making it impossible to distinguish the transmitting antennas along the time axis. Therefore, the range-Doppler map (RD map) of the reflected signal using the Doppler Division Multiple Access (DDMA) method can have as many peaks for the same target as the number of transmitting antennas, making it possible to distinguish data corresponding to each transmitting antenna along the Doppler axis.

[0068] If the physical antenna position cannot be found accurately, a mismatch to the antenna position occurs, which results in an inaccurate estimation of the target angle.

[0069] Fig. 5a is a range-Doppler map (RD map) of a reflected signal corresponding to a transmitted signal using a uniform phase step according to one embodiment of the present disclosure, Fig. 5b is a portion of Fig. 5a, Fig. 5c is a range-Doppler map (RD map) of a reflected signal corresponding to a transmitted signal using a non-uniform phase step according to a comparative embodiment, and Fig. 5d is a portion of Fig. 5c.

[0070] 5a and 5b, the radar device 10 according to one embodiment may radiate a transmission signal according to a uniform phase step, in which a phase step between phase shifts of a predetermined magnitude applied to each of a plurality of transmitting antennas is applied with the same magnitude. As a result, when 2D FFT data for reflected signals received by each of a plurality of receiving antennas is subjected to non-coherent integration (NCI), peaks for the same target may occur at equal intervals along the Doppler axis in a range-Doppler map.

[0071] In one embodiment, the radar device 10 may perform NCI with one peak for each transmitting antenna by dividing the Doppler axis into four equal parts and integrating them. This allows targets to be detected even if a peak drop occurs due to a gain difference in one of the multiple transmitting antennas, and the signal-to-noise ratio (SNR) for the peak can be improved by integrating each transmitting antenna. For example, when using uniform phase step, the SNR can be improved by up to four times (when the number of transmitting antennas is four) compared to when using non-uniform phase step.

[0072] Alternatively, the final data of the reflected signal may be 4Tx-4Rx NCI data corresponding to the transmitting antenna and the receiving antenna, respectively, as shown in FIG. 5b.

[0073] In contrast, referring to Figures 5c and 5d, when a non-uniform phase step is applied in which the phase steps between the phase shifts of a predetermined magnitude applied to each of the multiple transmitting antennas are different from each other, the 2D FFT data of the reflected signals received by each of the multiple receiving antennas has peaks for the same target appearing at different intervals in the Doppler axis direction in the range-Doppler map (RD map).

[0074] In other words, when non-uniform phase step is used, transmitting antennas can be separated using a preset phase difference in the Doppler axis direction, but when the range-Doppler map (RD map) is divided into four equal parts in the Doppler axis direction, two targets may appear as shown in Figure 5d. Therefore, four Rx NCI data peaks corresponding to the receiving antennas can be obtained, and if a peak drop occurs in one of the multiple transmitting antennas due to a gain difference, the target cannot be detected. In other words, when on-uniform phase step is used, the probability of peak detection failure increases, and the probability of target detection may decrease.

[0075] In the case of Non-Uniform Phase Step, the amount of calculation required to separate the transmit antennas is very large, and an additional calculation core may be required. In contrast, in the case of Uniform Phase Step, the NCI data is reduced to 1 / 4 of the data size compared to Non-Uniform Phase Step, which provides an advantage of four times the memory.

[0076] The radar device 10 according to one embodiment may acquire a range-Doppler map (RD map) by accumulating 2D FFT data of reflected signals for each of the transmitting antenna and the receiving antenna. In one embodiment, the radar device 10 may extract target candidates using a constant false alarm rate (CFAR). For example, CFAR may be a target detection algorithm commonly used in the radar device 10. CFAR may be used to detect the position of a peak in the range-Doppler map (RD map). For example, CA-CFAR, OS-CFAR, etc. may be used.

[0077] Figure 6a is a range-Doppler map (RD map) integrating 2D FFT data of reflected signals according to one embodiment of the present disclosure, while Figures 6b and 6c are examples of one-dimensional floating maps of the range-Doppler map of Figure 6a.

[0078] 6a, 6b, and 6c, when a radar device 10 according to one embodiment radiates transmission signals via multiple transmission antennas in accordance with Uniform Phase Step, and performs 2D FFT and NCI on the reflected signals resulting from reflection of at least a portion of the radiated transmission signals, peaks corresponding to the respective transmitting antennas can be obtained in a range-Doppler map (RD map).

[0079] In one embodiment, when the radar device 10 performs one-dimensional floating (1D-plotting) in the Doppler axis direction at the point where the peak occurs, a Doppler ambiguity phenomenon may occur, in which peaks with the same velocity interval occur, as shown in Figures 6b and 6c.

[0080] As shown in Figure 6b, the actual target speed is 2 m / s, but peaks of the same magnitude occur at 10.4 m / s, 18.87 m / s, and 27.31 m / s. The peak corresponding to transmitting antenna Tx1, which has a phase shift of 0°, is the Doppler component (True Doppler) for the actual target. The peak corresponding to transmitting antenna Tx2, which has a phase shift of 90°, is 10.4 m / s. The peak corresponding to transmitting antenna Tx3, which has a phase shift of 180°, is 18.87 m / s. The peak corresponding to transmitting antenna Tx4, which has a phase shift of 270°, is 27.31 m / s. Frequency shifts occur depending on the phase, which varies for each chirp.

[0081] In contrast, as shown in Fig. 6c as an example, although the actual target speed is 10.4 m / s, peaks of the same magnitude may occur at 2 m / s, 18.87 m / s, and 27.31 m / s, as in Fig. 6b. In other words, when using the Doppler Division Multiple Access (DDMA) method, the physical antenna position of the data corresponding to the reflected signal continues to change depending on the target speed, so additional processing may be required to match the data of the received reflected signal with the physical antenna position in order to identify the target speed.

[0082] In other words, due to the Doppler ambiguity phenomenon, peaks corresponding to the transmitting antennas appear in the range-Doppler map (RD map) of the reflected signal, so there may be uncertainty about the position of the transmitting antenna. Therefore, the radar device 10 of the present invention may resolve the Doppler ambiguity phenomenon by estimating the transmitting antenna in response to the reflected signal.

[0083] In one embodiment, the radar device 10 does not know the velocities of all n peak data, so it may resolve the Doppler ambiguity phenomenon by estimating the transmitting antenna for all peaks. Also, since the peaks differ for each frame, it may resolve the Doppler ambiguity phenomenon by estimating the transmitting antenna for all peaks each time a reflected signal is received.

[0084] The peak data (Peakdata[n][Tx_ch*Rx_ch]) of the reflected signal according to one embodiment is the result of a 2D FFT complex corresponding to the peak, and there may be n pieces of it depending on the number of peaks.

[0085]

number

[0086] Here, by way of example, Tx_ch may be 1 to 4, and Rx_ch may be 1 to 4.

[0087] According to an embodiment, the n-th peak data may include data corresponding to the number of transmitting antennas and receiving antennas (Tx_ch*Rx_ch=m). For example, if there are four transmitting antennas and four receiving antennas, the n-th peak data includes 16 pieces of data as follows:

[0088] The radar device 10 according to one embodiment may estimate a Doppler component (True Doppler) for an actual target, thereby estimating a plurality of transmitting antennas that are respectively matched to a plurality of peaks.

[0089]

number

[0090] 7a shows a physical arrangement of multiple transmit antennas Tx and multiple receive antennas Rx according to one embodiment of the present disclosure, and FIG. 7b shows a virtual array of multiple transmit antennas Tx and multiple receive antennas Rx according to one embodiment of the present disclosure.

[0091] 7a and 7b, a radar device 10 according to an embodiment may include a plurality of transmitting antennas Tx spaced apart from one another and a plurality of receiving antennas Rx spaced apart from one another, as shown in Fig. 7a. In an embodiment, the plurality of transmitting antennas Tx may be spaced apart from one another in the X-axis direction, the plurality of receiving antennas Rx may be spaced apart from one another in the X-axis direction, and the plurality of transmitting antennas Tx and the plurality of receiving antennas Rx may be spaced apart from one another in the Y-axis direction.

[0092] Based on the physical arrangement of the multiple transmitting antennas Tx and the multiple receiving antennas Rx included in the radar device 10 according to one embodiment, a virtual array antenna using MIMO may be formed as shown in FIG. 7b.

[0093] In one embodiment, the virtual array antenna may include multiple virtual receive antennas corresponding to multiple transmit antennas Tx1, Tx2, Tx3, and Tx4, respectively, by applying separate physical offsets from the multiple transmit antennas to the multiple receive antennas. For example, the virtual array antenna may apply only different X-axis offsets from the multiple transmit antennas Tx1, Tx2, Tx3, and Tx4 to the multiple receive antennas, and may not apply the same Y-axis offset for convenience.

[0094] In one embodiment of a virtual array antenna, multiple physical transmitting antennas Tx and multiple receiving antennas Rx may be arranged so that at least two or more virtual receiving antennas among multiple virtual receiving antennas generated based on multiple transmitting antennas and multiple receiving antennas overlap (folded array).

[0095] For example, as shown in FIG. 7b, the virtual receiving antenna [Tx3-Rx2] and the virtual receiving antenna [Tx4-Rx1] may overlap each other, and the virtual receiving antenna [Tx4-Rx3] and the virtual receiving antenna [Tx3-Rx4] may overlap each other.

[0096] The overlapping virtual receiving antennas in the virtual array antenna vary depending on the layout design of the multiple transmitting antennas and the multiple receiving antennas, and the more overlapping pairs of virtual receiving antennas there are, the higher the possibility of estimating the transmitting antennas and resolving the Doppler ambiguity phenomenon. However, the overlapping pairs of virtual receiving antennas in the virtual array antenna may reduce the overall MIMO aperture, causing performance degradation such as angular resolution and increasing calculation time.

[0097] In one embodiment, the defined n-th peak data is calculated by dividing the n-th peak data by the number of all cases (F n,1 , F n,2 , F n,3 , F n,4 ), the following formula is used. The phase step (θStep ) are applied sequentially, the number of possible configurations for multiple transmit antennas may be the same as the number of transmit antennas.

[0098]

number

[0099] Here, Tx and Ry refer to the physical locations corresponding to the transmitting and receiving antennas, respectively.

[0100] The radar device 10 according to one embodiment may match the frequency data of the reflected signal converted into the range-Doppler domain to a physical configuration derived from among multiple physical configurations for the multiple transmitting antennas and multiple receiving antennas.

[0101] In a MIMO virtual array antenna, signals received at the same location may have a very small physical phase difference. In one embodiment, in a virtual array antenna, the phase difference between overlapping virtual receiving antennas (folded array) among multiple virtual receiving antennas may be very small.

[0102] The radar device 10 according to one embodiment may derive any one of a plurality of physical arrangements for a plurality of transmitting antennas and a plurality of receiving antennas based on the phase difference between reflected signals received via at least two or more virtual receiving antennas arranged to overlap each other.

[0103] In one embodiment, a physical arrangement for multiple transmitting antennas and multiple receiving antennas may be derived that minimizes cost functions p1, p2, p3, and p4 that depend on the sum of the phase differences between reflected signals received via at least two or more virtual receiving antennas that are arranged to overlap.

[0104] For example, if the virtual receiving antennas [Tx3-Rx2] and [Tx4-Rx1] overlap each other, and the virtual receiving antennas [Tx4-Rx3] and [Tx3-Rx4] overlap each other, a cost function may be generated based on the phase difference between the reflected signals corresponding to T3R2 and T4R1, respectively, and the phase difference between the reflected signals corresponding to T3R4 and T4R3, respectively. For example, the cost function may be generated as follows:

[0105]

number

[0106] For example, the number of cases for physical antennas (F n,1 ), the cost function ∠F1(10)=f corresponds to T3R2 and T4R1, respectively. n,10 and ∠F1(13)=f n,13 and the phase difference between T3R4 and T4R3, respectively, ∠F1(12)=f n,12 and ∠F1(15)=f n,15 It may be generated by the sum of the phase differences between

[0107] For example, the number of cases for physical antennas (F n,2 ), the cost function ∠F2(14)=f corresponds to T3R2 and T4R1, respectively. n,14 and ∠F2(1)=f n,1 and the phase difference between T3R4 and T4R3, respectively, ∠F2(16)=f n,16 and ∠F2(3)=f n,3 It may be generated by the sum of the phase differences between

[0108] For example, the number of cases for physical antennas (F n,3 ), the cost function ∠F3(2)=f corresponds to T3R2 and T4R1, respectively. n,2 and ∠F3(5)=f n,5 and the phase difference between T3R4 and T4R3, respectively, ∠F3(4)=f n,4 and ∠F3(7)=fn,7 It may be generated by the sum of the phase differences between

[0109] For example, the number of cases for physical antennas (F n,4 ), the cost function ∠F4(6)=f corresponds to T3R2 and T4R1, respectively. n,6 and ∠F4(9)=f n,9 and the phase difference between T3R4 and T4R3, respectively, ∠F4(8)=f n,8 and ∠F4(11)=f n,11 It may be generated by the sum of the phase differences between

[0110] In one embodiment, the radar device 10 determines the physical antenna (f n,m =F n,k ) may be estimated.

number

[0111] For example, if k, which minimizes the cost function, is 3, then f n,9 ~f n,12 may be matched to the physical antenna Tx1.

[0112]

number

[0113] Therefore, the peak data (f n,m ) may be matched to a physical antenna, respectively. That is, the radar device 10 according to one embodiment may match the reflected signal acquired via the receiving antenna to the position of the transmitting antenna.

[0114] 8a is a graph of cost functions p1, p2, p3, and p4 as a function of angle according to one embodiment of the present disclosure. FIG. 8b is a range-Doppler map (RD map) for 2D FFT data of a reflected signal according to one embodiment of the present disclosure. The conspiracy data in FIG. 8a may have a Gaussian noise component added.

[0115] 8a and 8b, the radar device 10 according to one embodiment may simulate cost functions p1, p2, p3, and p4 according to angles for all possible physical antennas that can handle reflected signals. For example, the cost functions p1, p2, p3, and p4 may be functions according to Equation 9.

[0116] In one embodiment, the radar device 10 may arrange all the numbers of cases for the physical antennas ([Tx1 Tx2 Tx3 Tx4], [Tx2 Tx3 Tx4 Tx1], [Tx3 Tx4 Tx1 Tx2], [Tx4 Tx1 Tx2 Tx3]) at the peak corresponding to the number of transmit antennas (e.g., 4), as shown in Figure 8b, and simulate cost functions p1, p2, p3, and p4 for each number of cases.

[0117] As an example, as shown in Figure 8a, among the cost functions p1, p2, p3, and p4 for each number of cases, it can be seen that the cost function p1 for the [Tx1 Tx2 Tx3 Tx4] arrangement of physical antennas is the smallest.

[0118] In one embodiment, the radar system 10 may match the peaks of the reflected signal to the physical antenna arrangements that have the smallest cost functions p1, p2, p3, and p4, respectively.

[0119] FIG. 9 is a range-Doppler map (RD map) for 2D FFT data of reflected signals accumulated at a transmitting antenna and a receiving antenna, respectively, according to an embodiment of the present disclosure.

[0120] Referring to FIG. 9, the radar device 10 according to one embodiment may extract frequency components in the range domain or Doppler domain corresponding to the reflected signal based on the estimated position of the transmitting antenna, and obtain the distance or velocity of the target based on the extracted frequency components and the distance resolution or velocity resolution.

[0121] In one embodiment, the radar device 10 calculates a range index (R i ) and Doppler Index (D i ) containing the peak Index( <R i ,D i For example, the peaks may be the results of NCI and / or CFAR.

[0122] In one embodiment, the frequency resolution for the range axis and the Doppler axis in the 2D FFT may be equal to the distance resolution (ΔR=c / 2B, where c is the speed of light and B is the chirp bandwidth) and the velocity resolution (ΔV=λ / 2NcTc, where λ is the wavelength, Nc is the number of chirps, and Tc is the pulse repetition interval (PRI)), respectively.

[0123] In one embodiment, the radar device 10 may obtain the distance and / or velocity of the target by the product of the peak index and the range resolution and / or the velocity resolution. For example, the distance to the target is obtained by the product of the range index and the range resolution (R i ·ΔR), and the velocity relative to the target is the product of the Doppler Index and the velocity resolution (D i ·ΔV) may also be used.

[0124] Furthermore, to improve the accuracy of distance and / or velocity, a frequency estimation method may be used in a general distance or velocity estimation method. Since 2D FFT also provides data on the frequency axis, various frequency estimation methods can be used to improve the accuracy.

[0125] FIG. 10 is a flowchart 1000 of a method for processing radar signals according to one embodiment of the present disclosure.

[0126] Referring to FIG. 10, in operation 1010, the radar device 10 according to one embodiment may transmit radar signals via multiple transmit antennas Tx in a Doppler Division Multiplex Access (DDMA) manner.

[0127] In operation 1030, the radar device 10 according to the embodiment may receive, via a plurality of receiving antennas Rx, reflected signals in which at least a portion of the radar signal is reflected from a target.

[0128] In operation 1050, the radar device 10 according to one embodiment may generate a range-Doppler map (RD Map) based on the received reflected signals.

[0129] In operation 1070, the radar device 10 according to the embodiment may estimate which of the multiple transmitting antennas Tx corresponds to the reflected signal, based on the phase corresponding to the received reflected signal.

[0130] In operation 1090, the radar device 10 according to the embodiment may acquire radar data corresponding to the target based on the estimated transmitting antenna Tx and the reflected signal.

[0131] The method for processing radar signals in the radar device 10 described above may be embodied in the form of a computer program stored in a computer-readable recording medium that is executed by a computer or a recording medium containing computer-executable instructions. Also, the method for processing radar signals in the radar device 10 described above may be embodied in the form of a computer program stored in a computer-readable recording medium that is executed by a computer.

[0132] A computer-readable recording medium may be any available medium that can be accessed by a computer, including both volatile and nonvolatile media, and both detachable and non-detachable media. A computer-readable recording medium may also include a computer storage medium, including both volatile and nonvolatile, detachable and non-detachable media embodied in any method or technology for storing information such as computer-readable instructions, data structures, program modules, or other data.

[0133] The functionality provided by the components described herein may be implemented in general-purpose processors, application-specific processors, integrated circuits, application-specific integrated circuits (ASICs), central processing units (CPUs), MMICs (processing circuitry) including circuits and / or combinations thereof, programmed to perform the described functionality. A processor may include transistors and other circuitry and be considered a circuit or an MMIC. A processor may also be a programmed processor that executes a program stored in a memory.

[0134] In the present specification, a circuit, a part, a unit, or a means is hardware that is programmed to realize or performs the described functions, which may be all hardware disclosed in the present specification or any hardware known to be programmed to realize or perform the described functions.

[0135] In the case of a processor where the hardware is considered to be of the circuit type, the circuit, the part, means or unit is a combination of hardware and software used to configure the hardware and / or processor.

[0136] The above description of the present disclosure is for illustrative purposes only, and those skilled in the art will understand that the present disclosure can be easily modified into other specific forms without changing the technical spirit or essential features of the present disclosure. Therefore, it should be understood that the above-described embodiments are illustrative in all respects and not limiting. For example, each component described as a single component may be implemented in a distributed form, and similarly, each component described as a distributed component may be implemented in a combined form.

[0137] The scope of the present disclosure is indicated by the claims that follow rather than by the above detailed description, and all modifications and variations that fall within the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present disclosure.

Claims

1. In a radar device, a plurality of transmitting antennas; a plurality of receiving antennas; a monolithic microwave integrated circuit (MMIC) that controls the plurality of transmitting antennas and the plurality of receiving antennas, The MMIC comprises: transmitting radar signals via the plurality of transmitting antennas in a DDMA (Doppler Division Multiple Access) manner; receiving, via the plurality of receiving antennas, reflected signals of at least a portion of the radar signal reflected from a target; estimating a transmitting antenna corresponding to the reflected signal among the plurality of transmitting antennas based on a phase corresponding to the received reflected signal; configured to acquire radar data corresponding to the target based on the estimated transmitting antenna and the reflected signal. Radar equipment.

2. The radar signal includes a plurality of chirps with successively applied phase shifts of predetermined magnitudes. The radar device according to claim 1 .

3. The predetermined magnitude of phase shift is set differently for each of the plurality of transmitting antennas and maintained at a constant magnitude. The radar device according to claim 2 .

4. the plurality of transmitting antennas and the plurality of receiving antennas are arranged so that at least two or more virtual receiving antennas among a plurality of virtual receiving antennas generated based on the plurality of transmitting antennas and the plurality of receiving antennas overlap with each other. The radar device according to claim 1 .

5. The MMIC comprises: and applying a Fast Fourier Transform (FFT) to the received reflected signal to convert the received reflected signal into frequency components in a range-Doppler domain. The radar device according to claim 4.

6. The MMIC comprises: In the operation of estimating a transmitting antenna corresponding to each of the reflected signals among the plurality of transmitting antennas, a frequency data conversion unit configured to convert the frequency data of the reflected signals into the range-Doppler domain based on the phase of the reflected signals and to match the physical arrangement of the plurality of transmitting antennas and the plurality of receiving antennas; The radar device according to claim 5 .

7. The MMIC comprises: In the operation of estimating a transmitting antenna corresponding to each of the reflected signals among the plurality of transmitting antennas, deriving one of a plurality of physical arrangements for the plurality of transmitting antennas and the plurality of receiving antennas based on a phase difference between reflected signals received via at least two or more virtual receiving antennas arranged to overlap; configured to match the frequency data of the reflected signals converted into the range-Doppler domain to the derived physical location. The radar device according to claim 6.

8. The MMIC comprises: In the operation of acquiring radar data corresponding to the target, extracting a frequency component in a range region or a Doppler region corresponding to the reflected signal based on the estimated position of the transmitting antenna, and acquiring the distance or velocity of the target based on the extracted frequency component and a distance resolution or a velocity resolution. The radar device according to claim 6.

9. 1. A method for processing a radar signal, comprising: transmitting radar signals via multiple transmitting antennas using a Doppler Division Multiple Access (DDMA) method; receiving, via a plurality of receiving antennas, reflected signals of at least a portion of the radar signal reflected from a target; an operation of estimating a transmitting antenna corresponding to the reflected signal among the plurality of transmitting antennas based on a phase corresponding to the received reflected signal; and acquiring radar data corresponding to the target based on the estimated transmitting antenna and the reflected signal. A method for processing radar signals.

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