METHOD FOR PROCESSING COMMUNICATION SIGNALS AND VEHICLE RADAR SIGNALS FOR USE IN RADAR DETECTION, AND DEVICE EQUIPPED FOR PERFORMING THE METHOD

Abstract

A method for processing communication and vehicle radar signals for use in radar detection comprises receiving representations of a reflected communication signal reflected by one or more physical objects and an uninterrupted copy of the corresponding previously transmitted communication signal, and determining one or more first values ​​therefrom, each of which is associated with an assumed velocity and / or distance, relative to the transmitter / receiver, of corresponding first respective candidate objects.The method further comprises receiving representations of a reflected vehicle radar signal, reflected by one or more physical objects, and a corresponding interference-free reference vehicle radar signal, as well as determining at least one second value from these, which is related to an assumed speed and / or distance of corresponding second respective candidate objects relative to the radar transmitter / receiver. Based on the second value and the at least one first value, target acquisition is performed to identify and output probable physical objects, their speed, and / or distance.

Description

FIELD OF THE INVENTION

[0001] The invention relates to methods for processing communication and vehicle signals for use in radar detection, in particular to signal processing aimed at suppressing signal peaks caused by interference in the radar detection output signal. The invention also relates to a computer program product implementing the method, a computer-readable storage medium storing the computer program product, a device configured to carry out the method, and a vehicle having such a device. BACKGROUND

[0002] In recent years, vehicle radars have proliferated due to their critical and weather-independent role in safety and functional applications for intelligent transportation systems (ITS) and advanced driver assistance systems (ADAS). In addition to vehicle radar, vehicle-to-vehicle (V2V) communication has also become very important for ADAS, especially for automated or autonomous driving and teleoperation. However, with the increasing proliferation of vehicle radars, interference between vehicle radars has become a major obstacle to the proper operation of wireless systems such as vehicle radar and vehicle-to-everything (V2X) communication.

[0003] Modern vehicle radars use frequency-modulated continuous wave (FMCW) signals to detect the environment. Furthermore, all vehicles transmit more or less the same FMCW chirp waveform, which can lead to interference with the ego vehicle's radar, as shown in Fig. shown. Here, a first vehicle E, also referred to here as the ego vehicle, transmits a first FMCW vehicle radar signal, represented by the solid sawtooth line, to detect its surroundings. The FMCW vehicle radar signal moves towards a second vehicle T, also referred to here as the target vehicle. The target vehicle T transmits a second FMCW vehicle radar signal, represented by the dash-dotted sawtooth line, to detect its surroundings, which is moving towards the ego vehicle E. In addition, the first FMCW radar signal is reflected by the target vehicle T and returns to the ego vehicle E as the third FMCW radar signal, represented by the dashed sawtooth line. While the third radar signal is the signal of interest to the ego vehicle E, the superposition of the second and third radar signals can cause interference in the radar receiver of the ego vehicle E.

[0004] Interference leads to disturbing ghost signals in the radar detection of the ego vehicle, as in Fig. The presence of these ghost signals leads to an increase in the detection of phantom targets and thus to a deterioration in target acquisition performance, which can ultimately lead to undesirable consequences. The deterioration in target acquisition performance was demonstrated, for example, by G.M. Brooker in "Mutual interference of millimeter-wave radar systems," IEEE Transactions on Electromagnetic Compatibility, Vol. 49, No. 1, pp. 170-181, 2007, who discussed the nature and extent of interference for millimeter-wave radar systems and other sensor systems, taking into account spatial, temporal, and operational frequency-related overlaps under various operating conditions. Suppressing these ghost signals is therefore one of the most important challenges for vehicle-mounted radars.

[0005] A significant part of the state-of-the-art solutions aims to detect interference between millimeter-wave radars and then passively suppress the interference at the receiver, as discussed e.g. by Martin Kunert in “More Safety for All by Radar Interference Mitigation”, Dec 2012, PROJECT FINAL REPORT: MOSARIM project https: / / cordis.europa.eu / docs / projects / cnect / 1 / 248231 / 080 / deliverables / 001-D611finalreportfinal.pdf.

[0006] The general approach to interference mitigation relies on randomizing radar parameters in the time, frequency, space, code, and polarization domains, followed by detection and avoidance. However, existing passive interference mitigation techniques have limited effectiveness and are very complex for many vehicular radars installed in close quarters, as discussed by F. Liu, A. Garcia-Rodriguez, C. Masouros, and G. Geraci in "Interfering channel estimation in radar-cellular coexistence: How much information do we need?" IEEE Transactions on Wireless Communications, vol. 18, no. 9, pp. 4238-4253, 2019.

[0007] Recent advances in mmWave communications, which operate at or near wavelengths similar to vehicular radar, and work toward standardizing radio communications in the current 5G standard open the possibility of integrating radar and communications functions in the deployment of future V2X communications, smart cities, and smart roads. This broad paradigm of integrating radar and communications functions is known as Joint Radar and Communications (JRC) and is widely recognized as a new paradigm for 6G.

[0008] Solutions based on JRC are effective, simple, and require minimal hardware. Exemplary interference mitigation approaches based on JRC are presented by B. Li and A.P. Petropulu in "Joint transmit designs for coexistence of MIMO wireless communications and sparse sensing radars in clutter," IEEE Transactions on Aerospace and Electronic Systems, vol. 53, no. 6, pp. 2846-2864, 2017, presented by Y. Cui, V. Koivunen, as well as by Garcia-Rodriguez, C. Masouros, and G. Geraci, in “Interfering channel estimation in radar-cellular coexistence: How much information do we need?” IEEE Transactions on Wireless Communications, vol. 18, no. 9, pp. 4238-4253, 2019.

[0009] These approaches attempt to mitigate interference through precoding, beamforming, and resource allocation, which may require changes on the transmitter side and may not be feasible for older devices already deployed in large numbers and therefore will not have an immediate, significant positive impact.

[0010] It is therefore an object of the present invention to provide an improved method for processing vehicle radar signals and communication signals for use in radar detection. A further object of the invention is to provide an apparatus configured to implement and execute the method. DESCRIPTION OF THE INVENTION

[0011] These objects are achieved by the method according to claim 1 and the device according to claim 12. Advantageous embodiments and further developments of the method and the device are specified in the respective dependent claims.

[0012] The present invention will be described below with reference to a Fig. The initial situation shown here is similar to the one described above with reference to Fig. described. In addition to the radar signals, however, the V2V or V2X system in the ego vehicle E also transmits a separate communication signal following its FMCW chirp transmission, represented by the idealized transmission frame, which includes a random data part and a preamble part. The random data part is represented by the random pattern, and the preamble part by the regular checkerboard pattern. At approximately the same time, the vehicle radar in the target vehicle T transmits its own FMCW chirp signal to detect its surroundings. It is also assumed that the target vehicle T does not transmit any communication during the considered period. From the perspective of the ego vehicle E, the two transmitted signals are reflected by the target vehicle T and generate an FMCW radar echo and a communication echo, respectively. The FMCW radar echo is represented in the figure in the same way as in Fig. The communication echo is represented by the horizontally mirrored idealized transmission frame. As in the Fig. In the scenario shown, the second FMCW radar signal transmitted by the target vehicle T is superimposed in the radar receiver of the ego vehicle with the echo of the first FMCW radar signal, i.e., the signal reflected by the target vehicle T. The superimposed radar signals and the reflected communication signal are received by the respective receivers of the ego vehicle E for further processing. As mentioned above, the communication signal and the radar signal are transmitted in similar frequency ranges, e.g., 77 GHz for the FMCW radar signal and 60 GHz for the communication signal. Fig. shows a representation of the signals over time as they are sent and received by the ego vehicle. The left graph shows the transmission of the communication signal along the x-axis and the reflected echo arriving at a later time. Note that the echo is inverted due to the reflection. The right graph shows the transmission of the FCMW radar signal along the x-axis and the reflected echo arriving at a later time. It is obvious that the reflected echo and the FCMW radar signal transmitted by the target vehicle T are inverted in the radar receiver during the period t s overlap as long as they are both non-zero.

[0013] The transmitted communication signal usually conforms to a communication standard such as IEEE 802.11ad. Therefore, a typical communication signal transmission consists of a preamble part and a data part. It is assumed that the preamble signal p(t) is transmitted in single-carrier modulation format (SC). u p (t) is given by up(t)=∑k=0Np−1s(k)rect(t−kTcTc)exp(j2πfct), where s(k), k = 0,1, ..., N p - 1 are the preamble symbols to be transmitted and N p is the total number of preamble symbols. The pulse shape is defined as a rectangular pulse of duration T c accepted, and f c is the carrier frequency of the system.

[0014] In contrast, it is assumed that the data signal u d (t) is transmitted in OFDM format. u d (t) is given by ud(t)=∑k=0K−1∑l=0L−1S(kL+l)ej2πltTrect(t−kToTo)exp(j2πfct), where S(kL + l) represents the data symbol to be transmitted by the k-th OFDM block (symbol) over the l-th subcarrier. T o = T + T cp is the OFDM block duration, including the elementary symbol duration T and the duration T cpof the cyclic prefix (CP). It is assumed that a total of K OFDM blocks are to be transmitted, with each block being transmitted over L subcarriers.

[0015] The transmitted FMCW radar signal, also referred to here as chirp signal or chirp transmission, from both the ego vehicle E and the target vehicle T is an FMCW waveform with L c Chirps and is given by uc(t)=∑k=1Lcrect(t−kTpTp)ej2πfctejπBr(t−kTp)2, where T p the chirp duration, B r = B / T p is the modulation rate and B is the sweep bandwidth. It is assumed that the sweep bandwidth of the chirp transmission is identical to the operating bandwidth of the communication transmission.

[0016] It is assumed that all transmitted signals are reflected by M targets, generating M corresponding echoes. The receivers of the ego vehicle E receive a superposition of these M echo signals. At the communication receiver, the final baseband received signal for the SC preamble part can be expressed as follows after downconversion: yp(t)=∑k=0Np−1αms(k)rect(t−2dmc−kTcTc)e−j2π(fc2vmc)t+n(t), where a m the attenuation that occurs for the target m, d m the distance of the target m from the ego vehicle E, v m is the relative speed of the target m with respect to the ego vehicle E and c is the speed of light in vacuum.

[0017] Similarly, the final baseband receive signal for the block OFDM data payload part can be expressed as yd(t)=∑m=1M∑k=0K−1∑l=0L−1αmS(kL+l)ej2πl(t−2dmc)T x rect(t−kTo−2dmcTo)e−j2π(fc2vmc)t+n(t).

[0018] In the FMCW chirp receiver, the final 'dechirped' received signal is given by yc(t)=∑m=1M−1∑l=1Lcαmrect (t−Tp−2dmcTp)e(−j2π(2Brdmc)t) × e(−j2π(2fcvmTpc)l)+n(t).

[0019] In the communication receiver, the preamble and data payload parts of the received signal, i.e. y p (t),y d (t) are processed separately with appropriate matched filters to obtain the corresponding radar ambiguity functions (AF) for the preamble part and the data part. Similarly, in the FMCW chirp receiver, y c (t) to obtain the radar ambiguity function corresponding to the chirp signal.

[0020] The following section discusses the evaluation of these radar ambiguity functions. The ego vehicle E receives the communication echo signal and the chirped echo signal, which are processed in the communication receiver and the FMCW radar receiver, respectively. In the first step, both receivers sample the respective signals after downconversion and dechirping, as required.

[0021] The samples obtained by sampling the preamble part of the communication echo according to equation (4) are denoted by y p (n),n = 1,2, ...,N p Similarly, the samples obtained by sampling the data part of the communication echo according to equation (5) are denoted by y d (n), n = 1, 2, ..., N d The sample values ​​obtained by sampling the chirp signal are represented by the matrix Y c (n,l), with n = 0, 1, 2,..., N c and l = 1, 2, ..., L c .

[0022] In addition, the error-free reference samples for the preamble part, which is a copy of the preamble part of the baseband transmit communication signal, are denoted by x p (n),n = 1,2, ..., N p The error-free reference samples for the data part, which is a copy of the data part of the baseband transmit communication signal in which the cyclic prefix (CP) is replaced by a zero prefix (ZP), are denoted by x d (n),n = 1,2, ...,N d designated.

[0023] The AFs of the preamble and data parts of the communication signal are determined by the following steps: 1. Dividing the preamble part of the echo signal y p (n),n = 1,2, ...,N p and the corresponding error-free reference signal x p (n),n = 1,2, ...,N p in I p Segments of length N c . y p (in c+ j) denotes the preamble sample j from segment i. Analogously, x p (in c + j) the sample value j from the segment i of the error-free reference samples of the preamble part. 2. Dividing the data part of the echo signal y d (n), n = 1, 2, ..., N d and the data part of the error-free reference signal x d (n), n = 1,2, ...,N d in I d Segments of length N c . y(iN c + j) denotes the data sample j from segment i. Analogously, y c (in c + j) the sample j from the segment i of the error-free reference samples of the data part. 3. The AF for the preamble part is given by Apre(q,k)=1Np∑i=0lp−1∑j=0Nc−1x(iNc+j)xc∗(iNc+j−k)ej2πiqlp. 4. Accordingly, the AF for the data part is given by Adata(q,k)=1Nd∑i=0ld−1∑j=0Nc−1y(iNc+j)yc∗(iNc+j−k)ej2πiqld.

[0024] Chirp AF can be adjusted based on the chirp echo samples Y c (n, l) are evaluated as follows: 1. Calculate the FFT with N c Points across the columns of Y c (n,l) to Yc(q,l)=1Nc∑n=1NcYc(n,l)e−j2πqnNc,l=1,2,…Nc. 2. Calculate the Doppler FFT with I c Points over the rows q = 1,2, ...,N c by Y c (q, l) to, Ac(q,k)=1Lc(∑k=1lcYc∗(q,k)e−j2πlklc)∗=1Lc1Nc∑k=1lc∑n=1NcYc(n,k)e−j2n(qnNc−lklc)

[0025] It should be noted that the sampling rates of the communication receiver and the chirp receiver are usually very different. For example, the communication receiver typically samples the communication echo signal at F s = 1.76GHz, while the chirp radar detects the chirp echo signal with F s= 128 MHz. To enable the combination of the preamble AF, the data AF and the chirp AF according to equations (7), (8) and (11), the corresponding echo sequences must be padded with zeros so that I p = I d = I c .

[0026] In the following, a method according to the invention for processing communication signals and vehicle radar signals for use in radar detection, in particular for suppressing ghost peaks in a radar detection image from vehicle radars (Chirp AF), is discussed. A basic flowchart of the proposed method is shown in Fig. 4. The markings A and B refer to the signals emitted by the vehicle radar and to the method according to the invention, respectively, and are shown in the Fig. mentioned.

[0027] As described in the previous section, A pre (q, k), A data (q, k) and A c(q, k) are the respective AFs of the SC preamble part, the block OFDM data part, and the chirp AF. According to the present invention, a combined AF is generated by performing a pointwise minimum selection of the square of the magnitudes of the preamble AF A pre (q,k), the square of the magnitudes of the data AF A data (q, k) and the square of the magnitudes of the chirp AF A c (q, k) at each delay and each Doppler value range according to Amp(q,k)=min{|Apre(q,k)|2,|Adata(q,k)|2,|Ac(q,k)|2} is carried out.

[0028] If the sampling frequencies of the communication receiver and the vehicle radar receiver differ, as already mentioned, a suitable zero-filling can be performed before the pointwise minimum selection according to equation (12) in order to obtain the combined AF A mp (q,k).

[0029] Assuming that the target vehicle T does not transmit an interfering communication signal during the period of interest, any ghost signals that may occur in the preamble AF and the data AF are not caused by such a signal. However, even if the target vehicle T transmits a communication signal during the period of interest, it can be assumed that the data portion of the communication transmission of the target vehicle T is uncorrelated with the data portion of the communication transmission of the ego vehicle E. Since the communication transmission is regulated, it can also be ensured that different vehicles transmit different, uncorrelated preambles. In this case, the ghost signals in the preamble AF or the data AF are negligibly small.

[0030] To correctly acquire targets while simultaneously suppressing ghost signals, an appropriate target acquisition threshold must be set in combined AF. The following section presents the theoretical basis for this threshold setting.

[0031] As described in the previous section, the final AF A mp (q, k) is a two-dimensional function of time delay and Doppler frequency. For practical reasons, the two-dimensional representation can be divided into discrete bins, i.e., velocity bins for the Doppler axis and distance bins for the delay axis. This section describes the decision-making process as to whether a bin A mp (q, k) contains a target or not. Here, the decision is made based on the measurement of the energy of the respective bin E mp (q, k) = |A mp (q, k)| 2Since each bin has a certain energy floor due to noise, ghost signals, etc., it is essential to determine a suitable threshold η above which the energy in a bin can be considered to be attributable to a target, i.e. A mp (q,k) corresponds to a target if E mp (q, k) > η. Therefore, the decision about the presence or absence of a target for each delay Doppler bin of A mp (q, k), to a binary hypothesis testing problem, ie, H0:Amp(q,k)contains no target, H1:Amp(q,k) contains a target.

[0032] For this purpose, the following key performance indicators are defined: 1. Probability of a false alarm, P FA , PFA=ℙ(Emp>η;H0) 2. Detection probability, P D , PD=ℙ(Emp>η:H1). 3. Probability of suppression of disturbances, P r , Pr=ℙ(Emp<η:H1).

[0033] Given the above key performance indicators, the goal now mathematically reduces to: 1. Maximizing P D for the bins that correspond to the true target, and 2. Maximization of P r for the bins corresponding to the ghost signals (interference peaks), so that the interference rejection is high, while P FA is kept low. P FA can be adjusted by the user and is typically in a range between 10 -4 , 10 -6 .

[0034] The detection threshold η, which determines the probability of correct detection (P D ) for a given probability of a false alarm (P FA ) is given by η=−23σ2log(PFA) and the corresponding value of P D is given by PD=Q1(λpre,ησ2)Q1(λdata,ησ2)×Q1(λc,ησ2), where Q1(⋅) the Marcum Q-function and σ 2 is the noise variance. λ pre , λ dat and λ c are given by λpre=|Apre(q,k)|2σ2,λdata=|Adata(m,k)|2σ2,λc=|Ac(q,k)|2σ2.

[0035] To make a decision regarding a target, the energy in each field of the final AF, A mp (q, k), compared with the detection threshold η and explains the presence of the target in the field when the energy E mp (q,k) > η.

[0036] The combined final AF A mp(q, k) facilitates interference suppression for several reasons. First, it is assumed that the target vehicle T does not transmit an interfering communication signal during the considered time period. Therefore, a spurious signal peak in the preamble AF and the data AF cannot be caused by interference from a communication signal. Second, even if the target vehicle T were to transmit a communication signal during the considered time period, it can be assumed that the data part of the communication signal transmission from the target vehicle T is uncorrelated with the data part of the communication signal transmission from the ego vehicle E. Since the communication signal transmission is regulated, it can also be ensured that different vehicles transmit different, uncorrelated preambles. Thus, in this case, the spurious signal peaks that may occur in the preamble AF or the data AF will be negligibly small.Since each field in the final AF is obtained by the pointwise minimum of the square of the absolute values ​​of the corresponding bins in the preamble AF, the data AF, and the chirp AF, negligibly small noise values ​​in the data AF and the preamble AF that fill the bins containing noise in the final AF result in negligibly small values ​​in the bins corresponding to the interferer.

[0037] According to the first aspect of the invention, a method for processing communication signals and vehicle radar signals for use in radar detection therefore comprises receiving representations of a reflected communication signal received at a communication antenna, the communication signal having previously been transmitted via the communication antenna and having reflected off one or more physical objects, and a clean copy of the corresponding previously transmitted communication signal in a device configured to carry out the method. From the received representations of communication signals, one or more first values ​​are determined, each of which is respectively associated with an assumed speed and / or an assumed distance of one of one or more corresponding first respective candidate objects relative to the communication antenna.Alternatively, the method may comprise receiving one or more of the first values ​​at the device. The method further comprises receiving, at the device implementing the method, representations of a reflected vehicle radar signal received at a radar antenna, previously transmitted via the radar antenna and reflected by the one or more physical objects, and a corresponding interference-free reference vehicle radar signal. From the received representations of the vehicle radar signals, at least one second value is determined, which is associated with an assumed speed and / or an assumed distance of one or more corresponding second candidate objects relative to the radar antenna. Alternatively, the method may also comprise receiving at least one such second value.

[0038] The alternatives can be applied, for example, when a communication device and a radar device operate independently of the device implementing the method, and the device implementing the method acts as a supervisor to suppress false alarms, ie phantom radar objects.

[0039] At least the representations of a reflected vehicle radar signal may consist of superimposed signals or signal components transmitted by other radar antennas, although the representations of the communication signals may also consist of superimposed signals or signal components transmitted by other communication antennas.

[0040] In a further method step, a target detection is applied to the determined or received second and at least one first value in order to identify one or more probable physical objects in an environment of the communications antenna and / or the radar antenna. Finally, the result of the target detection is output, including information relating to objects in an environment of the communications and / or radar antenna, e.g. a speed and / or a distance of at least one probable physical object is output, if one has been identified. The output result can be used as such, i.e. as a true representation of the environment, or it can be used to supplement or correct data provided by a radar device.

[0041] In one or more embodiments of the method, determining one or more first values ​​comprises determining one or more first ambiguity functions from the communication signals. Alternatively, one or more such first ambiguity functions determined based on the communication signals can be received in the device performing the method.

[0042] In one or more embodiments of the method, the determining comprises determining respective ambiguity functions on the basis of a preamble of the communication signal and on the basis of the data part of this signal A pre , A data the determination of respective ambiguity functions based on a preamble of the communication signal and on the data part of this signal. Alternatively, one or more first ambiguity functions A pre , A datareceived which were determined on the basis of a preamble of the communication signal and on the basis of the data part thereof.

[0043] In one or more embodiments of the method, determining at least one second value comprises determining a second ambiguity function A c from the vehicle radar signals. Alternatively, at least a second ambiguity function A c , determined on the basis of the vehicle radar signals, is received in the device that performs the procedure.

[0044] In one or more embodiments of the method, performing target detection comprises assigning at least the one or more first and second candidate objects based on their respective assumed speed and their assumed distance, and eliminating unlikely candidate objects based on the respective associated second and at least one first value. This may include dividing the achievable speed and distance ranges covered by the processing of the communication signals and the radar signals, respectively, into corresponding discrete bins, and mapping a speed-range bin associated with a first candidate object to a corresponding speed-range bin available from the processing of the radar signals, regardless of the second value assigned to the respective bin.Similarly, a speed-distance bin associated with a second candidate object is assigned to a corresponding speed-distance bin available from the processing of the communication signals, regardless of the first value associated with the respective bin. In embodiments of the method, pairing can be performed only for candidate objects whose first or second value exceeds corresponding thresholds. This can, among other things, reduce the computational effort.

[0045] In one or more embodiments of the method, eliminating unlikely candidate objects comprises determining a threshold against which the second and at least one first value, or a third value derived therefrom, are compared. The comparison can be performed bin-by-bin for each speed-distance bin.

[0046] If the second and the at least one first value are included in the respective ambiguity functions, eliminating improbable object candidates may further comprise combining the received or previously determined first ambiguity function and the second ambiguity function into a combined ambiguity function A mp . This may further include, prior to combining, the received or previously determined one or more first ambiguity functions and the second ambiguity function A c be divided into corresponding discrete bins for combinations of distance and speed ranges and the combination is carried out bin by bin, with each bin of the combined ambiguity function A mp a third value is assigned which is derived from the second and at least one first value.

[0047] The bin-wise combination may comprise performing a bin-wise min-point selection for each corresponding distance and speed bin of the at least one first ambiguity function (A pre , A data ) and the second ambiguity function (A c ) include.

[0048] In one or more embodiments of the method, eliminating unlikely candidate objects comprises determining a threshold against which the third values ​​are compared.

[0049] In one or more embodiments of the method, first ambiguity functions are received or determined based on a preamble of the communication signal and based on its data part.

[0050] In one or more embodiments, the representations of the communication signals and the interference-free copy of the corresponding previously transmitted communication signal and / or the representations of the reflected radar signal and the corresponding interference-free reference radar signal are padded with zero values ​​before determining the respective ambiguity functions if the sampling frequencies at which the respective signals were sampled differ from each other.

[0051] In one or more embodiments, target detection comprises comparing a value representing a signal energy of each delay and Doppler bin of the combined ambiguity function to a predetermined detection threshold, wherein a target is considered to be found in a delay Doppler bin if the signal energy of that delay Doppler bin exceeds the detection threshold.

[0052] In the following section, simulation results are discussed to evaluate the performance of the proposed algorithm. The simulation setup considers the Fig. scenario shown and the system model described above.

[0053] The bandwidth B is assumed to be B = 1.76 GHz. Furthermore, it is assumed that the target vehicle T is at a distance of r = 150 dr m and is moving at a speed of v = 8 dv m / s. Where dr = c / 2B = 0.0852 m is the range resolution, i.e., the size of one bin in the range domain, and dv = λ / (2T f ) the velocity resolution, ie the size of a bin in the velocity range, where c is the speed of light in vacuum, λ = 5 mm corresponds to the wavelength and T f = 0.16 ms is the transmission time. The communication system of the ego vehicle E sends N f= 8 consecutive communication frames. The echo of these 8 frames, which are reflected by the target vehicle T, is received by the ego vehicle E. The preamble AF, A pre (q, k), and the data AF, A data (q, k) are then obtained by processing the communication echoes. Similarly, the vehicle radars of the ego vehicle E and the target vehicle T each transmit L c = 32 consecutive chirps. The duration of each chirp is T p = 5µs. The chirp echo reflected from the target vehicle T is received by the receiver of the ego vehicle E. In addition, the chirp transmission of the target vehicle T is also received by the receiver of the ego vehicle E. The superimposed chirp signal received at the receiver of the ego vehicle E is processed to determine the chirp AF, A c(q, k). It is assumed that the spurious signal peak in the radar image of the vehicle radar of ego vehicle E occurs at Bin (r = 30dr, v = 8dv). Subsequently, the final AF, A mp (q, k), by combining the preamble AF, the data AF and the chirp AF, A pre (q, k), A data (q, k) and A c (q, k), as described above. The threshold for target detection is determined by calculating the probability of a false alarm, P FA , on P FA = 10 -4 , is determined. For a signal consisting of samples x(n),n = 1,2, ..., N, ENR and SNR are defined as, ENR=∑n=1N|x(n)|2σ2,SNR=1N∑n=1N|x(n)|2σ2, where σ 2 is the noise variance.

[0054] The Fig. allow a comparison of the radar detection image of the conventional vehicle radar, designated A, and the proposed final AF, designated B, Amp . The following can be seen from the figure: • the target is detected at the correct location using both the conventional vehicle radar and the proposed method, and • the false signal peak, ie the ghost signal, appears in the conventional vehicle radar image and is suppressed by the proposed method.

[0055] The Fig. show a comparison of the target acquisition performance and the interference rejection performance of the proposed final AF, A mp , marked B in the figure, with the output of the conventional radar image, marked A in the figure. The following conclusions can be drawn from the figures: • The proposed method has a better target detection performance with a possible gain of up to 2 dB ENR over a wide range of P D compared to the conventional vehicle radar image, and • The proposed method has better performance in suppressing interference, with up to 100 times higher suppression performance compared to the conventional vehicle radar image. Fig. show a significant improvement in target detection performance and interference suppression performance. This suggests that the proposed method effectively suppresses interference and improves target detection compared to conventional vehicle radar detection.

[0056] In the previous results, it was assumed that the chirp transmission and the communication transmission have the same duration. As mentioned above, the proposed method also works when the chirp transmission duration differs from the communication transmission duration. However, there may be a loss in detection performance if the data transmission duration is chosen to be shorter. The final simulation result in Fig. shows that to achieve the same P D the required signal-to-noise ratio (SNR) is 5 dB higher when the transmission time of the chirp signal is eight times (8) the transmission time of the communication signal, ie Tfc=8Tfcomm. This is typically the case in practical systems where communication transmission occurs in bursts of very short duration. This suggests that the proposed algorithm is applicable in a practical setting.

[0057] According to a second aspect of the present invention, an apparatus for processing communication signals and vehicle radar signals for use in radar detection is presented. The apparatus comprises one or more input interfaces configured to receive representations of a communication signal received at a communication antenna and reflected from one or more physical objects, a clean copy of the corresponding previously transmitted communication signal, a radar signal received at a radar antenna and reflected from the one or more physical objects, and a corresponding clean reference radar signal. The clean copy of the corresponding previously transmitted communication signal may be received from a memory in which it was stored prior to transmission.The reference radar signal may be taken from a memory and supplemented by information indicating a relative or absolute time of transmission of the radar signal whose reflection or echo is being processed. The representations of the received signals may be provided as sampled versions of the signals or in preprocessed form, e.g., in the form of signals representing one or more ambiguity functions determined based on the corresponding signals. The one or more input interfaces may be implemented by one or more physical interfaces that receive the signals, sampled versions of the signals, or corresponding data representing the signals, and may include one or more logical interfaces that store the data and forward it to corresponding processing modules.The various elements of the device may be provided in hardware, software, or a combination thereof. The device may further comprise one or more microprocessors and associated volatile and non-volatile memory. The non-volatile memory stores computer program instructions which, when executed by the one or more microprocessors, configure the device to perform one or more embodiments of the method according to the first aspect of the invention, as set forth above.

[0058] The method described above can be represented by computer program instructions. Accordingly, a computer program product comprises computer program instructions that, when executed by a microprocessor of a computer or device according to the second aspect of the invention, cause the computer to perform one or more embodiments of a method according to the first aspect of the present invention and / or to control hardware and / or software blocks or modules of the device according to the second aspect of the invention accordingly, as set out above.

[0059] The computer program instructions may be stored or transmitted in a retrievable manner on a computer-readable medium or storage medium. The medium or storage medium may be physically embodied, e.g., in the form of a hard disk, a solid-state disk, a flash memory, or the like. However, the medium or storage medium may also comprise a modulated electromagnetic, electrical, or optical signal that is received by the computer via a corresponding receiver and transmitted to and stored in a memory of the computer.

[0060] The present invention proposes a novel method that post-processes the independent radar detection results obtained by processing the FMCW echo from the vehicle radar and a communication signal echo from the same vehicle. In the proposed method, a radar-like detection result obtained by appropriately processing the echoes of communication signals reflected from a target is used to suppress spurious signal peaks in the radar detection image that may be present due to radar signals transmitted independently of the target, thereby improving target detection performance.

[0061] The performance of interference suppression can be evaluated by evaluating the probability of suppression (P r) for ghost targets. Theoretical analyses and simulations show that the proposed method together with the derived optimized threshold achieves better target detection performance with up to 2 dB higher ENR relative to P D and up to 100 times better interference suppression performance relative to P r at high ENR. These improvements lead to more reliable automotive radar / detection systems by reducing the likelihood of false alarms.

[0062] The gain in interference rejection can be achieved at the cost of very little additional processing complexity at the receiver and without any additional cost or complexity on the transmit side. SHORT DESCRIPTION OF THE DRAWING

[0063] The invention is described below with reference to the drawing.

[0064] In the figures, identical or similar elements may be referred to by the same reference numerals. DESCRIPTION OF EXAMPLES OF WORKING MODELS The Fig. have already been discussed above and will not be discussed again here.

[0065] Fig. shows a flowchart of an exemplary embodiment of the method 100 according to the present invention. In step 110a, representations of a reflected communication signal received at a communication antenna, which was previously transmitted via the communication antenna and which was reflected by one or more physical objects, are received in a device 400 implementing the method. Furthermore, a clean copy of the corresponding previously transmitted communication signal is received in the device 400. In step 120, one or more first values ​​are determined, each of which is respectively associated with an assumed speed and / or an assumed distance of one of one or more corresponding first respective candidate objects relative to the communication antenna.Alternatively, in step 110b, one or more such first values ​​are received in the device 400, the alternative being indicated by the dashed outline of the box. In embodiments of the method, step 120 may include a step 122a for determining one or more first ambiguity functions (AF) or a step 122b for receiving one or more such first AFs. As throughout the figure, the alternative is indicated by the dashed outline of the box. The method further includes, in step 130a, receiving representations of a reflected vehicle radar signal received at a radar antenna, previously transmitted via the radar antenna and reflected by the one or more physical objects, and a corresponding interference-free reference vehicle radar signal in the device 400 implementing the method.In step 140, at least one second value associated with an assumed speed and / or an assumed distance of one or more corresponding second candidate objects relative to the radar antenna is determined from the received representations of vehicle radar signals. Alternatively, at least one such second value is received in step 130b. In embodiments of the method, step 140 may include a step 142a for determining a second AF from the vehicle radar signals or a step 142b for receiving a second ambiguity function determined based on the vehicle radar signals. In step 150, target detection is performed using the determined or received second and at least one first value to identify one or more likely physical objects.If at least one probable physical object is detected, a corresponding associated speed and / or distance is output in step 160 in the "Yes" branch of step 158. Otherwise, in the "No" branch of step 158, the execution of the method is repeated, beginning with the receiving steps 110a and 130a or 110b and 130b.

[0066] In embodiments of the method, step 150 may include a step 152 of assigning at least one or more first and second candidate objects based on their respective assumed speed and their assumed distance, and a step 156 of eliminating improbable candidate objects based on the respective associated second and at least one first value. Elimination step 156 may be preceded by a step 154 ​​of determining a threshold value with which the second and at least one first value, or a third value derived therefrom, are compared.In embodiments of the method, step 156 may comprise a step 156-1 of dividing the received or previously determined one or more first ambiguity functions and the second ambiguity function into respective discrete bins for combinations of distance and speed ranges and a step 156-2 of bin-wise combining the received or previously determined one or more first ambiguity functions and the second ambiguity function into a combined ambiguity function, wherein each respective discrete bin for combinations of distance and speed ranges is assigned a third value derived from the second and the at least one third value.

[0067] Fig.shows a schematic block diagram of an exemplary device 400 configured to perform the method according to the first aspect of the invention. An input interface 402, a microprocessor 404, a volatile memory 406, and a non-volatile memory 408 are connected by one or more signal and / or data lines or buses 410. The non-volatile memory 408 stores computer program instructions that, when executed by the microprocessor 404, configure the device 400 to perform the method according to the first aspect of the invention. LIST OF REFERENCE SYMBOLS (PART OF THE DESCRIPTION) 100 procedures 110a Receive representations of the communication signal 110b first values ​​received Determine 120 first values 122a determine first AF(s) 122b first AF(s) received 130a Receive representations of radar signals 130b receive second values Determine 140 second values 150 Perform target acquisition Assign 152 candidate objects 154 Determine threshold Eliminate 156 unlikely candidate objects 156-1 Divide AFs into bins 156-2 Binary combining 156-3 Compare 158 possible physical object recorded? 160th issue 400 device 402 Input interface 404 microprocessor 406 volatile memory 408 non-volatile memory 410 Data / signal line / bus E Ego vehicle T Target vehicle QUOTES CONTAINED IN THE DESCRIPTION

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

[0000] GM Brooker in “Mutual interference of millimeter-wave radar systems”, IEEE Transactions on Electromagnetic Compatibility, Vol. 49, No. 1, pp. 170-181, 2007

[0004] Martin Kunert in “More Safety for All by Radar Interference Mitigation”, Dec 2012, PROJECT FINAL REPORT: MOSARIM project https: / / cordis.europa.eu / docs / projects / cnect / 1 / 248231 / 080 / deliverables / 001-D611finalreportfinal.pdf

[0005] von F. Liu, A. Garcia-Rodriguez, C. Masouros und G. Geraci in „Interfering channel estimation in radar-cellular coexistence: How much information do we need?“ IEEE Transactions on Wireless Communications, vol. 18, no. 9, pp. 4238-4253, 2019

[0006] B. Li und A. P. Petropulu in „Joint transmit designs for coexistence of MIMO wireless communications and sparse sensing radars in clutter,“ IEEE Transactions on Aerospace and Electronic Systems, vol. 53, no. 6, pp. 2846-2864, 2017

[0008] Y. Cui, V. Koivunen

[0008] X. Jing in „Interference alignment based spectrum sharing for mimo radar and communication systems,“ 2018 IEEE 19th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC), 2018, pp. 1-5

[0008] F. Liu, A. Garcia-Rodriguez, C. Masouros, and G. Geraci, in „Interfering channel estimation in radar-cellular coexistence: How much information do we need?“ IEEE Transactions on Wireless Communications, vol. 18, no. 9, pp. 4238-4253, 2019

[0008]

Claims

[1] A method (100) for processing communication signals and vehicle radar signals for use in radar detection, comprising: - receiving (110a), in a device (400) implementing the method, representations of a reflected communication signal received at a communication antenna, which was previously transmitted via the communication antenna and reflected at one or more physical objects, and a noise-free copy of the corresponding previously transmitted communication signal, and determining (120) one or more first values from the received representations of communication signals, each of which is associated with an assumed speed and / or an assumed distance of one of one or more corresponding first respective candidate objects relative to the communication antenna, or receiving (110b) one or more of the first values at the device (400), - receiving (130a), in the device (400) implementing the method, representations of a reflected vehicle radar signal received at a radar antenna, which was previously transmitted via the radar antenna and reflected by the one or more physical objects, and a corresponding interference-free reference vehicle radar signal, and determining (140) at least one second value from the received representations of the vehicle radar signals, which is associated with an assumed speed and / or an assumed distance of one or more corresponding second candidate objects relative to the radar antenna, or receiving (130b) at least one such second value, - applying (150) a target detection to the determined or received second and at least one first value to detect one or more probable physical objects, and - Outputting (160) a speed and / or a distance of at least one probable physical object, if one has been detected. [2] The method (100) of claim 1, wherein determining (120) one or more first values comprises: - determining (122a) one or more first ambiguity functions from the communication signals, or receiving (122b) one or more first ambiguity functions determined on the basis of the communication signals. [3] Method (100) according to claim 1 or 2, wherein determining (122a) one or more first ambiguity functions (A pre , A data ) comprises determining respective ambiguity functions on the basis of a preamble of the communication signal and on the basis of the data part of this signal, or receiving (122b) one or more first ambiguity functions (A pre , A data) receiving respective first ambiguity functions determined on the basis of a preamble of the communication signal and on the basis of the data part of that signal. [4] Method (100) according to one or more of claims 1 to 3, wherein determining (140) at least one second value comprises: - determining (142a) a second ambiguity function (A c ) from the vehicle radar signals, or receiving (142b) a second ambiguity function (A c ). [5] Method (100) according to one or more of claims 1 to 4, wherein applying (150) a target detection comprises: - Assigning (152) at least the one or more first and second candidate objects based on their respective assumed speed and their assumed distance, and - eliminating (156) unlikely candidate objects on the basis of the respective associated second and at least one first value. [6] The method (100) of claim 5, wherein eliminating (154) unlikely candidate objects comprises determining (154) a threshold value with which the second and at least one first value or a third value derived therefrom are compared. [7] The method (100) of claim 5 when dependent on claims 3 and 4, wherein eliminating (156) unlikely candidate objects further comprises: - subdividing (156-1) the received or previously determined one or more first ambiguity functions (A pre , A data ) and the second ambiguity function (A c ) into corresponding discrete bins for combinations of distance and speed ranges, - bin-wise combining (156-2) the received or previously determined one or more first ambiguity functions (A pre , A data ) and the second ambiguity function (A c ) into a combined ambiguity function (A mp ), wherein each discrete bin for a combination of distance and speed range is assigned a third value derived from the second and at least one first value. [8] The method (100) of claim 7, wherein said bin-wise combining (156-2) comprises performing a bin-wise min-point selection for each corresponding distance and speed bin of said at least one first ambiguity function (A pre , A data ) and the second ambiguity function (A c ) includes. [9] The method (100) of claim 7 or 8, wherein eliminating (156) unlikely candidate objects comprises determining (156-3) a threshold against which the third values are compared. [10] Method (100) according to one or more of claims 3 to 9, further comprising zero-padding the representations of the communication signals and / or the radar signals before determining the respective ambiguity function if the sampling frequencies with which the respective signals were sampled differ from one another. [11] Method (100) according to one or more of claims 3 to 10, wherein the target detection comprises comparing a value (E mp ) which represents a signal energy of each delay and Doppler bin of the combined ambiguity function (A mp), with a given detection threshold (η), where a target is considered to be found in a delay Doppler bin if the signal energy (E mp ) of this delay Doppler bin exceeds the detection threshold (η). [12] An apparatus (400) configured to process communication signals and vehicle radar signals for use in radar detection, comprising one or more input interfaces (402) configured to receive representations of a communication signal received at a communication antenna and reflected by one or more physical objects, a clean copy of the corresponding previously transmitted communication signal, a radar signal received at a radar antenna and reflected by the one or more physical objects, and a corresponding clean reference radar signal, and further comprising one or more microprocessors (404) and associated volatile (406) and non-volatile (408) memory, the elements of the apparatus being communicatively connected by means of one or more signal and / or data lines and / or buses (410),wherein the non-volatile memory (408) stores computer program instructions which, when executed by the one or more microprocessors (404), configure the apparatus (400) to perform the method according to any one of claims 1 to 11. [13] A computer program product comprising computer program instructions which, when executed by the microprocessor of a computer or device (400) according to claim 12, cause the computer and / or control hardware blocks, modules or components of the device (400) according to claim 12 to carry out a method (100) according to any one of claims 1 to 11. [14] A computer-readable medium or data carrier which transmits or stores the computer program product according to claim 13 in a retrievable manner. [15] Vehicle, road-side unit or edge computing unit comprising a device (400) according to claim 12.

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