SIGNAL PROCESSING EQUIPMENT, SIGNAL PROCESSING METHOD AND SIGNAL PROCESSING PROGRAM

Abstract

An attack detection unit (241) determines whether an attack using a spoofing signal is present by detecting jitter caused by the attack using the spoofing signal from a beat signal (S8). Once the jitter has been detected by the attack detection unit (241), a post-countermeasure information calculation unit (242) calculates tracking information (S11) after removing information about distance and velocity observed due to the spoofing signal. An information selection unit (243) selects the tracking information to use from the tracking information (S11) and the tracking information (S9) generated from the beat signal (S8).

Description

Technical field

[0001] The present disclosure relates to a signal processing system of a radar that detects a target object. State of the art

[0002] A radar is a device that measures the relative distance between the radar and a target object, as well as the relative speed between the radar and the target object, by emitting radio waves towards the target object and measuring the waves reflected by the target object.

[0003] The FMCW method is a radar measurement technique. FMCW is cost-effective yet offers excellent capabilities for measuring distance and speed. In particular, the fast FMCW method has a higher resolution than the conventional slow FMCW method. With the fast FMCW method, the sweep time of a chirp signal is a few microseconds, making it relatively short. FMCW stands for Frequency Modulated Continuous Wave.

[0004] Spoofing attacks during radar operation pose a threat. A spoofing attack is an attack in which external radio waves, mimicking a measurement, are inserted into the radar's radio waves to trick the radar into detecting an object that does not actually exist.

[0005] In non-patent literature 1, an attack method is proposed that spoofs the distance, speed, and angle of a Fast-Chirp FMCW radar. An attack setup using SDR (Software Defined Radio) is employed for the spoofing attacks.

[0006] In non-patent literature 2, an attack method is proposed that spoofs the distance of a slow-chirp FMCW radar. For spoofing attacks, an attack device is used that combines a radar board with a microcomputer. It is also noted that for a precise spoofing attack, a synchronization error resulting from the individual differences between the radar boards of an attacker and a victim must be absorbed. Reference list Non-patented literature

[0007] Non-Patent Literature 1: Zhi Sun, et al. "Who is in control? Practical Physical Layer Attack and Defense for mmWave-based Sensing in Autonomous Vehicles" IEEE Transactions on Information Forensics and Security 16 (2021): 3199-3214.

[0008] Non-Patent Literature 2: Shoei Nashimoto, et al. “Low-cost distance-spoofing attack on FMCW radar and its feasibility study on countermeasure.” Journal of Cryptographic Engineering 11.3 (2021): 289-298. Summary of the invention: Technical problem

[0009] Non-patent literature 1 and non-patent literature 2 describe spoofing attack methods. However, neither non-patent literature 1 nor non-patent literature 2 describes methods that allow for the accurate identification of a target during a spoofing attack.

[0010] The purpose of this disclosure is to enable the correct detection of a target, even when a spoofing attack is carried out. Solution to the problem

[0011] A signal processing device according to the present disclosure comprises an attack detection unit to determine whether or not an attack using a spoofing signal is present, by detecting jitter caused by the attack using the spoofing signal from a beat signal; and a post-countermeasure information calculation unit to calculate tracking information when the jitter has been detected by the attack detection unit, after information about a distance and velocity observed due to the spoofing signal has been removed. Advantageous effects of the invention

[0012] In the present disclosure, objects can be detected even during a spoofing attack using a spoofed signal by removing a fake target object created by the attack. Thus, it is possible to correctly detect a target even when a spoofing attack is being carried out. Brief description of the drawings Fig. Figure 1 is a configuration representation of a radar device 100 according to embodiment 1; Fig. Figure 2 is a hardware configuration representation of a signal processing device 200 according to embodiment 1; Fig. Figure 3 is a flowchart illustrating a procedure for the operation of the radar device 100 according to embodiment 1; Fig. Figure 4 is a flowchart of a spoofing presence determination process according to embodiment 1; Fig. Figure 5 is a diagram describing a method for detecting an attack based on a synchronization error due to individual differences in the radar according to embodiment 1; Fig. 6 is a flowchart of a first attack determination process according to embodiment 1; Fig. Figure 7 is a diagram describing a method for detecting an attack based on the number of impersonations according to embodiment 1; Fig. 8 is a flowchart of a second attack determination process according to embodiment 1; Fig. Figure 9 is a flowchart of a post-countermeasure information calculation process according to embodiment 1; Fig. 10 is a flowchart of a second filter process according to embodiment 1; Fig. Figure 11 is a flowchart of a first filtering process according to embodiment 1; Fig. 12 is a flowchart of a second information selection process according to embodiment 1; Fig. Figure 13 is a flowchart of the spoofing presence determination process according to variant 1; Fig. Figure 14 is a flowchart of the post-countermeasure information calculation process according to variant 1; Fig. Figure 15 is a configuration representation of the radar device 100 according to variant 2; Fig. Figure 16 is a flowchart illustrating a procedure for the operation of the radar device 100 according to variant 2; Fig. Figure 17 is a flowchart of the post-countermeasure information calculation process according to variant 2; Fig. 18 is a flowchart of the second filtering process according to variant 2; Fig. Figure 19 is a flowchart of the post-countermeasure information calculation process according to variant 3; Fig. Figure 20 is a flowchart of the first filtering process according to variant 3; Fig. Figure 21 is a flowchart of the post-countermeasure information calculation process according to variant 4; and Fig. Figure 22 is a flowchart of the second filtering process according to variant 4. Description of embodiments

[0013] In the embodiments and drawings, identical or corresponding elements are designated with the same reference numerals. The description of an element designated with the same reference numeral as an element already described is omitted or simplified where necessary.

[0014] Arrows in diagrams primarily indicate signal, data, or processing flows. A filled circle is drawn at a branching point where a signal or data flows in multiple directions. Design 1.*** Configuration Description ***

[0015] With reference to the Fig. 1 and Fig. 2 describes a configuration of a radar device 100 according to embodiment 1.

[0016] The radar device 100 calculates the distance, speed, and angle of a target object using radar measurements and tracks the target object. The target object is an object detected by radar measurement. The target object distance is the distance between the radar device 100 and the target object. The target object speed is the speed of the target object relative to the radar device 100. The target object angle is the horizontal and vertical angle that indicates the position of the target object relative to the radar device 100. Tracking information is a record of the changes in the target object's distance, speed, and angle over time.

[0017] The radar device 100 comprises an analog front end 110 and a signal processing unit 200.

[0018] The analog front end 110 is an analog circuit. It comprises circuits such as a waveform generator 111, a VCO 112, a transmitting antenna 113, a receiving antenna 114, a mixer 115, a low-pass filter 116, and an ADC 117. These circuits are interconnected by signal lines. VCO stands for voltage-controlled oscillator. ADC stands for analog-to-digital converter.

[0019] As in Fig. As shown in Figure 2, the signal processing device 200 is a computer comprising hardware such as a processor 201, a memory 202, and an input / output interface 203. These hardware components are interconnected via signal lines.

[0020] The Processor 201 is an integrated circuit (IC) that performs operational processing and controls other hardware components. For example, the Processor 201 could be a CPU, a DSP, or a GPU. IC stands for Integrated Circuit. CPU stands for Central Processing Unit. DSP stands for Digital Signal Processor. GPU stands for Graphics Processing Unit.

[0021] The term "RAM 202" refers to both volatile and non-volatile memory devices. A specific example of a volatile memory device is RAM. Specific examples of non-volatile memory devices are ROM, a hard disk, and flash memory. RAM stands for Random Access Memory. ROM stands for Read Only Memory. HDD stands for Hard Disk Drive.

[0022] The 203 input / output interface is an interface for input and output. For example, the 203 input / output interface is a serial communication interface. Specific examples of serial communication interfaces are SPI, UART, or 12C. SPI stands for Serial Peripheral Interface. UART stands for Universal Asynchronous Receiver / Transmitter. 12C stands for Inter-Integrated Circuit.

[0023] The signal processing unit 200 comprises, as functional components, a waveform control unit 210, a waveform accumulation unit 220, an information processing unit 230, and an attack countermeasures unit 240. The attack countermeasures unit 240 comprises an attack detection unit 241, a post-countermeasures information processing unit 242, and an information selection unit 243. The functional components of the signal processing unit 200 are implemented by software.

[0024] The working memory 202 stores a signal processing program that implements the functional components of the signal processing device 200. The signal processing program is executed by the processor 201.

[0025] Memory 202 also stores an operating system (OS). The OS is executed by processor 201. Processor 201 runs the signal processing program while the OS is running. OS is an abbreviation for Operating System.

[0026] Input and output data of the radar operating program are stored in the working memory 202.

[0027] The signal processing unit 200 can contain a variety of processors as an alternative to the processor 201.

[0028] The radar operating program can be recorded (stored) in a computer-readable format on a non-volatile recording medium such as an optical disk or flash memory. *** Description of a business ***

[0029] In the Fig. Sections 3 to 12 describe the operation of the radar device 100 according to embodiment 1.

[0030] A sequence for operating the radar device 100 according to embodiment 1 corresponds to a radar operating procedure. A sequence for operating the signal processing unit 10 according to embodiment 1 corresponds to a signal processing unit according to embodiment 1. The sequence for operating the signal processing unit 10 according to embodiment 1 also corresponds to a sequence for processing by the signal processing program according to embodiment 1.

[0031] With reference to Fig. Section 3 describes the procedure for operating the radar device 100 according to embodiment 1. (Step S110: Local wave transmission process)

[0032] The analog frontend 110 transmits a local wave S3.

[0033] Specifically, the waveform control unit 210 generates a control signal S1 and outputs the generated control signal S1. Based on the control signal S1, the waveform generator 111 outputs a ramp signal S2 to control the VCO 112. The VCO 112 generates the local wave S3 with an oscillation frequency based on the ramp signal S2 and outputs the generated local wave S3. (Step S120: Beat signal generation process)

[0034] The analog frontend 110 receives a received wave S4 and generates a beat signal S7.

[0035] Specifically, the receiving antenna 114 receives a radio wave as the received wave S4 and outputs the received wave S4. The received wave S4 corresponds to the local wave S3 (radio wave) reflected by the target object or similar. When the radio wave is reflected by the target object, its frequency changes. Therefore, the received wave S4 contains information about a frequency change resulting from the distance and speed of the target object. If the receiving antenna 114 consists of multiple antennas, each antenna has a phase difference resulting from the angle of the target object.

[0036] Mixer 115 performs mixing of the received wave S4 and the local wave S3 in step S113. This mixing is equivalent to signal multiplication and can be expressed as expression 1. cos(fst)⋅cos(frt)=[cos{(fs−fr)t}+cos{(fs+fr)t}] / 2 "fs" represents the frequency of the local wave S3. "fr" represents the frequency of the received wave S4. "cos" represents a cosine function. "t" represents time. "fs" and "fr" typically represent frequencies that change over time. Specifically, "fs" and "fr" represent frequencies corresponding to chirp signals.

[0037] A signal generated by this mixing is called the mixing signal S5. Mixer 115 outputs the generated mixing signal S5. The output mixing signal S5 is fed into the low-pass filter 116.

[0038] The low-pass filter 116 filters out components other than the low-frequency components of the mixed signal S5. A signal generated in this way is called the filtered signal S6. The filtered signal S6 corresponds to the low-frequency components extracted from the mixed signal S5. That is, it represents the components cos{(fs - fr)t}.

[0039] The ADC 117 converts the filtered signal S6, which is an analog signal, into a digital signal. Specifically, the ADC 117 quantizes the filtered signal S6. The resulting digital signal is called the beat signal S7. (Step S130: Waveform accumulation process)

[0040] The waveform accumulation unit 220 accumulates the beat signal S7 in the working memory 202 on a frame-by-frame basis. The accumulated beat signal S7 is then processed as the beat signal S8 on a frame-by-frame basis. The beat signal S8 is therefore a signal with dimensions whose number corresponds to the sampling time × the number of waveforms × the number of antennas. (Step S140: Information Calculation Process)

[0041] The information processing unit 230 calculates the distance, speed, and angle of the target object based on the beat signal S8 and outputs tracking information S9. This is how FMCW radar signals are normally processed.

[0042] Specifically, the Information Processing Unit 230 calculates an RD map by performing a 2D FFT on the beat signal S8 and determines the distance and velocity of the target object. Furthermore, the Information Processing Unit 230 calculates the angle using an angle-finding algorithm, such as a beamforming method. Additionally, the Information Processing Unit 230 uses the calculated distance, velocity, and angle information to output tracking information S9 of the target object using a tracking algorithm, such as a Kalman filter. 2D FFT is an abbreviation for the two-dimensional fast Fourier transform. The RD map stands for the range Doppler map. The RD map has dimensions whose number is range bins × Doppler bins × the number of antennas. (Step S150: Spoofing presence determination process)

[0043] The attack detection unit 241 determines, based on the beat signal S8, whether a spoofing attack is present and outputs an attack detection result S10. The details of the process in step S150 are described later.

[0044] If the attack detection result S10 indicates that a spoofing attack is present, processing continues with step S170. If the attack detection result S10 indicates that no spoofing attack is present, processing continues with step S160.

[0045] (Step S160: First information selection process)

[0046] The information selection unit 243 selects the tracking information S9 calculated in step S140.

[0047] (Step S170: Post-Countermeasure Information Calculation Process)

[0048] The post-countermeasure information calculation unit 242 calculates the distance, speed, and angle of the target object based on the attack determination result S10 and outputs tracking information S11. The details of the process from step S170 are described later. (Step S180: Second information selection process)

[0049] Information selection unit 243 selects the final tracking information based on tracking information S9 and tracking information S10. The details of the process from step S180 are described later. (Step S190: Information recording process)

[0050] The Information Selection Unit 243 records the tracking information in memory 202. Recording tracking information is the retention of information as recorded information for a specific period of time. For example, the Information Selection Unit 243 can perform the recording in a ring buffer format and use finite memory to retain the records for a specific period.

[0051] With reference to Fig. 4. The spoofing presence determination process according to embodiment 1 (step S150 in Fig. 3) described. The Attack Detection Unit 241 determines whether a spoofing attack is occurring by detecting two attack characteristics. One of the attack characteristics is a synchronization error resulting from individual differences in the radar. The other attack characteristic is the number of chirps during which the spoofing was successful (number of spoofing events). (Step S151: First Attack Determination Process)

[0052] The Attack Detection Unit 241 determines whether or not an attack using a spoofing signal is present based on a synchronization error caused by individual radar differences. Specifically, the Attack Detection Unit 241 determines whether an attack using a spoofing signal is present by detecting jitter caused by a spoofing attack.

[0053] If it is determined that an attack is present, processing continues with S155 and the attack detection unit 241 determines that an attack is present (1). If it is determined that no attack is present, processing continues with S152.

[0054] The details of the process for step S151 will be described later. (Step S152: Second attack determination process)

[0055] The Attack Detection Unit 241 determines whether an attack using a spoofing signal is present based on the number of deceptions. Specifically, the Attack Detection Unit 241 determines whether an attack using a spoofing signal is present by detecting a break in the spoofing signal.

[0056] If it is determined that an attack is present, processing continues with S154 and the attack detection unit 241 determines that an attack is present (2). If it is determined that no attack is present, processing continues with S153 and the attack detection unit 241 determines that no attack is present.

[0057] The details of the process for step S152 will be described later.

[0058] With reference to Fig. Section 5 describes a method for detecting an attack based on a synchronization error due to individual differences in the radar according to embodiment 1.

[0059] Fig. Figure 5 describes how the high-energy frequency changes waveform-wise when the range FFT is performed on the beat signal S8. The signal reflected from the target object does not change significantly within a frame, even if the target object moves, so it appears as a straight line with a slope of 0. In the case of a spoofing signal, however, a synchronization error appears as a difference in the sweep time, so the distance appears to change gradually in each waveform. It therefore appears as a straight line with a slope. The range FFT represents an operation to perform the FFT in one direction of time.

[0060] The process for capturing the aforementioned attack characteristic is the first attack identification process (step S151 in Fig. 4).

[0061] With reference to Fig. 6 will be the first attack determination process according to embodiment 1 (step S151 in Fig. 4) described. (Step S1511: Range spectrum calculation process)

[0062] The attack determination unit 241 applies the range FFT to the beat signal S8 to calculate a range spectrum. The calculated range spectrum is a signal with dimensions whose number is the number of range bins × the number of waveforms. (Step S1512: Peak frequency calculation process)

[0063] The attack detection unit 241 calculates a frequency peak for each waveform within the spectrum calculated in step S1511. This calculated frequency peak appears for the target object or for each spoofed object contained in the spoofing signal. (Step S1513: Slope Calculation Method)

[0064] The attack detection unit 241 applies linear regression to the frequency peak to calculate a slope. If a large number of frequency peaks are observed, linear regression is applied after they have been clustered using an algorithm such as DBSCAN.

[0065] This means that the Attack Determination Unit 241 calculates a slope obtained by expressing the frequency peak of each waveform as a linear function of a waveform number. In other words, the Attack Determination Unit 241 calculates a slope *a* by setting the frequency peak as *y* and the waveform number as *x*, and fitting them into an expression *y* = *ax* + *b*. DBSCAN is an abbreviation for Density-based spatial clustering of applications with noise.

[0066] If the calculated slope exceeds a slope threshold, i.e., if a change in distance over time is observed, processing proceeds to step S1515 and the attack detection unit 241 determines that an attack is present. That is, if the calculated slope exceeds the slope threshold, the attack detection unit 241 confirms that jitter caused by a spoofing attack has been detected and determines that an attack is present.

[0067] If the slope is equal to or less than the slope threshold, processing continues with step S1514 and the attack detection unit 241 determines that no attack is present. That is, if the calculated slope is equal to or less than the slope threshold, the attack detection unit 241 determines that no jitter caused by a spoofing attack has been detected and determines that no attack is present.

[0068] Referring to Fig. Section 7 describes a method for detecting an attack based on the number of impersonations according to embodiment 1.

[0069] Fig. Figure 7 describes how the high-energy frequency changes in a waveform when the domain FFT is performed on the beat signal S8. The signal reflected from the target object is continuously observed over a series of frames. However, it is possible that a spoofing signal will not mimic all chirps and will disappear halfway through. Alternatively, the signal may emerge from a chirp in the middle.

[0070] The process for detecting the aforementioned attack characteristic is the second attack identification process (step S152 in Fig. 4).

[0071] With reference to Fig. 8 will be the second attack determination process according to embodiment 1 (step S152 in Fig. 4) described. (Step S1521: Range spectrum calculation process)

[0072] The attack determination unit 241 applies the range FFT to the beat signal S8 to calculate a range spectrum. The calculated range spectrum is a signal with dimensions whose number is the number of range bins × the number of waveforms × the number of antennas. (Step S1522: Difference calculation process)

[0073] The attack detection unit 241 calculates a difference in the range spectrum between adjacent waveforms.

[0074] If the calculated range spectrum is expressed as X[range bin][waveform][number of antennas], the calculated difference can be expressed as X_DIFF ← X[:][i][:] - X[:][i+1][:], where i is an integer from 1 to the number of waveforms - 1 and [:] represents all data pieces of this dimension.

[0075] The attack detection unit 241 checks the difference between adjacent spectra for each i from i = 1 down to the number of waveforms - 1 and determines whether the absolute value of the difference exceeds a difference threshold. That is, the attack detection unit 241 observes a large change in the spectrum when a signal suddenly disappears or appears. The attack detection unit 241 identifies an attack when a large change is observed.

[0076] If the absolute value of the difference exceeds the difference threshold, processing continues with step S1524 and the attack detection unit 241 determines that an attack has occurred. That is, if the absolute value of the difference exceeds the difference threshold, the attack detection unit 241 confirms that an interruption in a spoofing signal has been detected and determines that an attack has occurred.

[0077] If the absolute value of the difference is equal to or less than the difference threshold, processing continues with step S1523 and the attack detection unit 241 determines that no attack is present. That is, if the absolute value of the difference is equal to or less than the difference threshold, the attack detection unit 241 confirms that no interruption in a spoofing signal has been detected and determines that no attack is present.

[0078] With reference to Fig. 9 the post-countermeasure information calculation process according to embodiment 1 (step S170 in Fig. 3) described.

[0079] The attack detection unit 241 detects an attack based on the two types of attack characteristics. The post-countermeasure information calculation unit 242 therefore checks which of the attack characteristics is used to determine whether an attack has occurred. If an attack has occurred (1), this detection is based on a physical characteristic, so processing continues with step S173.

[0080] If the case of an attack (1) is not the case, the case of an attack (2) is determined. In the case of an attack (2), this detection is based on the number of fakes, so that processing continues with step S171. (Step S171: First filtering process)

[0081] The post-countermeasure information processing unit 242 filters the beat signal S8 based on the interruption of the spoofing signal. The details of the process in step S171 are described later. (Step S172: Map Calculation Process)

[0082] The post-countermeasure information calculation unit 242 calculates an RD map from the beat signal S8 filtered in step S171. (Step S173: Second filtering process)

[0083] The post-countermeasure information processing unit 242 filters the RD map calculated in step S140 based on the synchronization error. The details of the process in step S173 are described later. (Step S174: Information Calculation Process)

[0084] The post-countermeasure information calculation unit 242 calculates a distance, a velocity, and an angle based on the RD map obtained in steps S172 and S173 and generates tracking information. The process of generating tracking information from the RD map corresponds to the process of step S140 in Fig. 3.

[0085] With reference to Fig. 10. The second filter process according to embodiment 1 (step S173 in Fig. 9) described. (Step S1731: Speed ​​calculation process)

[0086] The post-countermeasure information calculation unit 242 calculates the speed resulting from the action taken in step S1513. Fig. The calculated slope is observed. The time required to transmit a chirp is the sweep time Ts. That is, the slope is a change in distance per unit of time and thus the velocity. Here, the post-countermeasure information processing unit 242 obtains the velocity from the slope a by converting the number of waveforms into time. That is, the post-countermeasure information processing unit 242 obtains the velocity by a ÷ Ts. The post-countermeasure information processing unit 242 converts this velocity into the nearest Doppler bin. (Step S1732: Distance calculation process)

[0087] The post-countermeasure information calculation unit 242 calculates the distance to the object in step S1512 in Fig. 6 calculated value of the frequency peak. That is, the post-countermeasure information calculation unit 242 identifies a range bin that represents the frequency peak resulting from the signal with the aforementioned slope. (Step S1733: Signal exclusion process)

[0088] The post-countermeasure information processing unit 242 excludes frequencies with the range bin and the Doppler bin resulting from the spoofing signal from the RD map calculated in step S140. That is, the post-countermeasure information processing unit 242 excludes frequencies with the range bin identified in step S1732 and the Doppler bin identified in step S1731 from the RD map calculated in step S140.

[0089] For example, the post-countermeasure information calculation unit treats 242 signals near the corresponding range bin and Doppler bin as invalid values. This can be expressed as expression 2. RD[R−Rofs:R+Rofs][D−Dofs:D+Dofs][:]←N / A

[0090] R and D represent the range bin number and the Doppler bin number corresponding to the spoofing signal resulting from the spoofing signal. Rofs and Dofs represent filtering parameters. N / A indicates an invalid value. For example, the minimum value of the RD card might be specified as N / A.

[0091] With reference to Fig. 11. The first filtering process according to embodiment 1 (step S171 in Fig. 9) described.

[0092] The post-countermeasure information processing unit 242 re-examines the difference in the spectrum calculated in step S1522 during attack detection and determines whether the difference is greater than 0. That is, the post-countermeasure information processing unit 242 checks which of the old and new spectrums is temporally larger and thus causes the difference. If the signal disappears in the second half of the frame, as in Fig. 7, the difference becomes greater than 0.

[0093] If the difference is greater than 0, processing continues with step S1712. If the difference is equal to or less than 0, processing continues with step S1711. (Step S1711: First deletion process)

[0094] The post-countermeasure information processing unit 242 deletes from the beat signal S8 the beat signal corresponding to the waveform number at which the difference was observed, and the subsequent waveform numbers. That is, the post-countermeasure information processing unit 242 only deletes the beat signal affected by the attack. (Step S1712: Second deletion process)

[0095] The post-countermeasure information processing unit 242 deletes from the beat signal S8 the beat signal corresponding to the waveform number at which the difference was observed, and the preceding waveform numbers. That is, the post-countermeasure information processing unit 242 only deletes the beat signal affected by the attack.

[0096] With reference to Fig. 12. The second information selection process according to embodiment 1 (step S180 in Fig. 3) described. (Step S181: Record comparison process)

[0097] Information selection unit 243 compares a recording of tracking information previously recorded in step S190 with the tracking information S11 output in step S170. The recording of tracking information previously recorded in step S190 is, for example, the tracking information recorded in step S190 of the preceding time.

[0098] If a difference exists, processing continues with step S182. If no difference exists, processing continues with step S183. (Step S182: First takeover process)

[0099] Information selection unit 243 accepts the tracking information S9. That is, information selection unit 243 determines that the visible target object has been eliminated by the filtering performed as a countermeasure, and accepts the tracking information S9 calculated directly from the beat signal S8 without applying the countermeasure. (Step S183: Second takeover process)

[0100] Information selection unit 243 accepts the tracking information S11. That is, information selection unit 243 determines that the spoofing signal, which was not present, has been successfully eliminated by the filtering performed as a countermeasure, and accepts the tracking information S11 by applying the countermeasure. *** Effects of embodiment 1 ***

[0101] As described above, the signal processing device 200 according to embodiment 1 performs signal processing to extract information from a beat signal within the framework of the conventional FMCW method.

[0102] Specifically, the information processing unit 230 calculates the tracking information S9 based on the beat signal S8 on a frame-by-frame basis. Simultaneously, the attack detection unit 241 performs an attack detection based on the beat signal S8 on a frame-by-frame basis and generates the attack detection result S10. Based on the attack detection result S10, the post-countermeasure information processing unit 242 generates a filtered RD map, excludes the spoofing signal, and then calculates the tracking information S11.The Information Selection Unit 243 detects an attack that exploits a countermeasure by using the tracking information S9 and the tracking information S11, which are calculated using two different methods depending on whether the countermeasure is applied or not, and which refers to a past tracking information record, and outputs corresponding tracking information.

[0103] The attack detection unit 241 detects an attack by exploiting a synchronization error due to individual differences in the radar, which is present in an attack using a spoofing signal, or by the possibility that the spoofing of an entire frame fails. If an attack is detected, the post-countermeasure information processing unit 242 removes the spoofing signal from the radar map. This means it is possible to detect and defend against a spoofing attack.

[0104] The information selection unit 243 determines whether there is a target object that was present in a previous tracking information record but disappears after the countermeasure is applied, and outputs corresponding tracking information. This means it is possible to detect and defend against an attack that uses filtering as a countermeasure to remove an existing target object. *** Other configurations ***<Variante 1>

[0105] As option 1, only a recording based on a synchronization error can be carried out.

[0106] The configuration of the radar device 100 according to variant 1 is in Fig. 1 shown. Fig. 13 represents the spoofing presence determination process according to variant 1 (step S150 of Fig. 3) The radar device 100 according to variant 1 determines, based on a synchronization error, whether an attack is present or not. Accordingly, in the post-countermeasure information calculation process (step S170 in Fig. 3), as in Fig. Figure 14 shows only the process of filtering the RD card based on a synchronization error. <Variante 2>

[0107] In variant 2, when an attack is detected due to a synchronization error, information originating from a spoofing signal can be excluded from the tracking information.

[0108] Fig. 15 represents a configuration of radar device 100 according to variant 2. A difference to Fig. 1 consists of the tracking information S9 being passed as input to the post-countermeasure information calculation unit 242. Accordingly, the operating sequence of the radar device 100 is changed, as in Fig. 16 shown. Fig. 16. The process from step S170 in Fig. 3 in the process of step S270. In step 270, the post-countermeasure information calculation unit 242 generates the tracking information S11 based on the beat signal S8, the attack determination result S10 and the tracking information S9.

[0109] With reference to Fig. 17. The post-countermeasure information calculation process according to variant 2 (step 270 in Fig. 16) described.

[0110] The processes from step S171 to step S172 and step S174 are the same as in the post-countermeasure information calculation process according to embodiment 1 (step 170 in Fig. 3). In step 273, the post-countermeasure information calculation unit 242 filters the tracking information based on a synchronization error.

[0111] With reference to Fig. 18. The second filter process according to variant 2 (step S273 in Fig. 17) described.

[0112] The processes from step S1731 to step S1732 are the same as those in the second filter process according to embodiment 1 (step 173 in Fig. 9).

[0113] In step S2733, the post-countermeasure information processing unit 242 excludes tracking information about the distance and velocity that correspond to the detected spoofing signal from the tracking information S9. For example, if distance, velocity, and angle are used as tracking information, the post-countermeasure information processing unit 242 excludes all parts of the tracking information where a match between distance and velocity is detected. <Variante 3>

[0114] As a third option, the RD card can also be filtered if an attack is detected based on the number of deceptions. Fig. 19 represents the post-countermeasure information calculation process according to variant 3 (step S170 of Fig. 3) The processes from step S173 to step S174 are the same as those in the post-countermeasure information calculation process according to embodiment 1 (step 170 in Fig. 3). In step 271, the post-countermeasure information calculation unit 242 filters the RD map calculated in step S140 based on the interruption in the spoofing signal.

[0115] With reference to Fig. 20 will be the first filtering process according to variant 3 (step 271 in Fig. 19) described.

[0116] First, as in step 171, the difference in the range spectrum calculated in step S1522 during attack detection is checked again to determine if it is greater than 0. If the difference is greater than 0, processing continues with step S2712. If the difference is equal to or less than 0, processing continues with step S2711. (Step S2711: First deletion process)

[0117] The post-countermeasure information processing unit 242 deletes from the beat signal S8 the beat signal corresponding to the waveform number at which the difference was observed, and the preceding waveform numbers. That is, the post-countermeasure information processing unit 242 only deletes the beat signal not affected by the attack. This operation is a process in which the deleted signal is reversed with respect to step S1711. (Step S2712: Second deletion process)

[0118] The post-countermeasure information processing unit 242 deletes from the beat signal S8 the beat signal corresponding to the waveform number at which the difference was observed, and the subsequent waveform numbers. That is, the post-countermeasure information processing unit 242 only deletes the beat signal not affected by the attack. This operation is a process in which the deleted signal is reversed with respect to step S1712.

[0119] The subsequent processes are the same as those of step S151 and step S173. That is, the post-countermeasure information calculation unit 242 calculates the distance and speed, according to the spoofing signal, based on a change in distance and filters out corresponding frequencies from the RD map. <Variante 4>

[0120] As a fourth option, the beat signal can also be filtered if an attack is detected based on a synchronization error. Fig. 21 represents the post-countermeasure information calculation process according to variant 4 (step S170 of Fig. 3) The processes from step S171 to step S172 and the process of step S174 are the same as in the post-countermeasure information calculation process according to embodiment 1 (step 170 in Fig. 3). In step 473, the post-countermeasure information calculation unit 242 filters the beat signal S8 based on the synchronization error.

[0121] With reference to Fig. 22 the second filter process according to variant 4 (step S473 in Fig. 21) described.

[0122] The processes from step S1731 to step S1732 are the same as those in the second filter process according to embodiment 1 (step 173 in Fig.9) In step S4733, the post-countermeasure information processing unit 242 filters out distance and velocity frequencies corresponding to the spoofing signal from the beat signal. For example, the post-countermeasure information processing unit 242 uses a notch filter to filter out frequencies with the range bin corresponding to the spoofing signal in a sampling time direction, and uses a notch filter to filter out frequencies with the Doppler bin corresponding to the spoofing signal in a waveform direction. <Variante 5>

[0123] In embodiment 1, the functional components are implemented by software. In variant 5, however, the functional components can also be implemented by hardware. The differences between variant 5 and embodiment 1 are described below.

[0124] If the functional components are implemented by hardware, the signal processing unit 10 has an electronic circuit instead of the processor 201 and the main memory 202. The electronic circuit is a dedicated circuit that implements the functions of the functional components and the main memory 202.

[0125] The electronic circuit is specifically a single circuit, a composite circuit, a programmed processor, a parallel-programmed processor, a logic IC, a GA, an ASIC, or an FPGA. GA is an abbreviation for Gate Array. ASIC is an abbreviation for Application Specific Integrated Circuit. FPGA is an abbreviation for Field-Programmable Gate Array.

[0126] The functional components can be implemented by a single electronic circuit, or the functional components can be distributed across and implemented by a multitude of electronic circuits. <Variante 6>

[0127] In variant 6, some of the functional components can be implemented by hardware and the rest of the functional components by software.

[0128] The processor 201, the main memory 202, and the electronic circuitry are all referred to as a processing circuit. This means that the functions of the functional components are implemented by the processing circuit.

[0129] “Unit” in the above description can be interpreted as “circuit”, “step”, “sequence”, “process” or “processing circuit”.

[0130] The embodiment and variants of the present disclosure have been explained above. Two or more of these embodiments and variants can be implemented in combination. Alternatively, one, two, or more of them can be partially implemented. The present disclosure is not limited to the embodiment and variants mentioned above, and various modifications can be made as required. For example, a MIMO (multi-input multi-output) radar with a plurality of transmitting antennas 113 and a plurality of receiving antennas 114 can be used. In this case, the number of low-pass filters 105 and ADCs 106 can correspond to the number of receiving antennas 114. Reference symbol list

[0131] 100: Radar device, 110: Analog front end, 111: Waveform generator, 112: VCO, 113: Transmitting antenna, 114: Receiving antenna, 115: Mixer, 116: Low-pass filter, 117: ADC, 200: Signal processing unit, 201: Processor, 202: Main memory, 203: Input / output interface, 210: Waveform control unit, 220: Waveform accumulation unit, 230: Information processing unit, 240: Attack countermeasures unit, 241: Attack determination unit, 242: Post-countermeasures information processing unit, 243: Information selection unit. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited non-patent literature

[0000] Zhi Sun, et al. „Who is in control? Practical Physical Layer Attack and Defense for mmWave-based Sensing in Autonomous Vehicles“ IEEE Transactions on Information Forensics and Security 16 (2021): 3199-3214

[0007] Shoei Nashimoto, et al. „Low-cost distance-spoofing attack on FMCW radar and its feasibility study on countermeasure.“ Journal of Cryptographic Engineering 11.3 (2021): 289-298

[0008]

Claims

[1] Signal processing device comprising: an attack determination unit for determining whether or not an attack using a spoofing signal is present by detecting jitter caused by the attack using the spoofing signal from a beat signal; and a post-countermeasure information calculation unit for calculating, when the jitter is detected by the attack determination unit, tracking information after removing information about a distance and a speed observed due to the spoofing signal. [2] The signal processing device according to claim 1, wherein the attack determination unit confirms that the jitter has been detected when a slope exceeds a slope threshold, the slope being obtained by representing a frequency peak of each waveform in a domain spectrum of the beat signal by a linear function of a waveform number. [3] Signal processing device according to claim 1 or 2, wherein the attack determination unit determines whether or not the attack using the spoofing signal exists by detecting a break in the spoofing signal from the beat signal, and wherein, when the interruption has been detected, the post-countermeasure information calculation unit calculates the tracking information by extracting only a part not affected by the attack from the beat signal. [4] The signal processing device according to claim 3, wherein the attack determination unit confirms that the interruption has been detected when an absolute value of a difference between adjacent waveforms in a range spectrum of the beat signal exceeds a difference threshold. [5] The signal processing device according to any one of claims 1 to 4, wherein, when the jitter has been detected, the post-countermeasure information calculation unit calculates the tracking information after removing information about a distance and a speed observed due to the spoofing signal from a range Doppler (RD) map generated from the beat signal. [6] The signal processing device according to any one of claims 1 to 4, wherein, when the jitter has been detected, the post-countermeasure information calculation unit excludes a target object having a distance and a speed observed due to the spoofing signal from the tracking information generated from the beat signal. [7] The signal processing device according to any one of claims 1 to 4, wherein, when the jitter has been detected, the post-countermeasure information calculation unit calculates the tracking information after removing information about a distance and a speed observed due to the spoofing signal from the beat signal. [8] Signal processing device according to claim 1 or 2, wherein the attack determination unit determines whether or not the attack using the spoofing signal exists by detecting an interruption of the spoofing signal from the beat signal, and wherein, when the interruption has been detected, the post-countermeasure information calculation unit uses only a beat signal affected by the attack from the beat signal to calculate information about a distance and a speed observed due to the spoofing signal, and calculates tracking information after removing the calculated information about the distance and the speed. [9] A signal processing device according to any one of claims 1 to 8, further comprising an information selecting unit for referring to a record of tracking information and selecting tracking information to be adopted from tracking information calculated by the post-countermeasure information calculating unit and tracking information calculated directly from the beat signal. [10] The signal processing device according to claim 9, wherein the information selecting unit selects the tracking information calculated directly from the beat signal when a target object present in the recording of the tracking information is not present in the tracking information calculated by the post-countermeasure information calculating unit. [11] Signal processing method comprising: Determining, by a computer, whether or not an attack using a spoofing signal is present by detecting jitter caused by the attack using the spoofing signal from a beat signal; and Calculating, by a computer, when the jitter has been detected, tracking information after removing information about a distance and a speed observed due to the spoofing signal. [12] Signal processing program that causes a computer to act as a signal processing device to perform: an attack determination process of determining whether or not an attack using a spoofing signal exists by detecting jitter caused by the attack using the spoofing signal from a beat signal; and a post-countermeasure information calculation process of, when the jitter is detected by the attack determination process, calculating tracking information after removing information about a distance and a speed observed due to the spoofing signal. [13] Signal processing device comprising: an attack determination unit for determining whether or not an attack using a spoofing signal is present by detecting a break in the spoofing signal from a beat signal; and a post-countermeasure information calculation unit for, when the interruption is detected by the attack determination unit, extracting only a part not affected by the attack from the beat signal to calculate tracking information. [14] Signal processing device comprising: an attack determination unit for determining whether or not an attack using a spoofing signal is present by detecting a break in the spoofing signal from a beat signal; and a post-countermeasure information calculation unit for, when the interruption has been detected by the attack determination unit, using only a beat signal affected by the attack from the beat signal to calculate information about a distance and a speed observed due to the spoofing signal, and calculating tracking information after removing the calculated information about the distance and the speed.

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