A target detection method and device

Abstract

An embodiment of the present application relates to a target detection method, and the method includes: sending a communication cooperation sequence signal including a detection sequence component. The detection sequence component is an MS-QP sequence with multiple subbands, and each subband includes a narrowband ZC sequence. Receiving an echo signal of the communication cooperation sequence signal and performing FFT to determine a radar detection component in the frequency domain. Correlating the detection sequence component with the radar detection component to determine at least one correlation peak and the delay information corresponding to each correlation peak. Determining at least one target and the target distance corresponding to each target according to at least one correlation peak and the delay information corresponding to each correlation peak. The communication cooperation sequence signal sent by the present application has good autocorrelation characteristics for target detection. At the same time, through multiple subbands, the large bandwidth occupied by the transmitted information is divided into multiple narrowbands, so that a low-sampling-rate ADC can be used when receiving the echo signal to reduce the hardware cost.

Description

Technical Field

[0001] This application relates to the field of communications, and in particular, to a target detection method and apparatus based on a terahertz communication detection integrated waveform. Background Art

[0002] The terahertz frequency band has extremely rich spectrum resources, which can provide an ultra-high available bandwidth, thereby supporting high-speed data transmission of hundreds of gigabits per second (Gbps). This meets the requirements of many data services for ultra-high transmission rates under the rapid development of wireless communications. It can be seen that terahertz communication may become one of the key technologies for 6th generation (6G) mobile communication technology. In addition to the communication function, due to the large amount of available bandwidth in the terahertz frequency band, it can be used for target detection or sensing to effectively improve the target ranging resolution and detection accuracy. On the other hand, due to the extremely narrow beam of terahertz signals, it can effectively reduce the clutter interference caused by multipath when used for radar detection. Therefore, the application prospect of terahertz signals in detection is very broad. Since both terahertz communication and detection systems require the occupation of ultra-wide spectrum resources and have high manufacturing costs. Therefore, in-depth research on terahertz communication detection is required, such as terahertz communication detection integration. Terahertz communication detection integration can effectively reduce equipment costs, reduce equipment size and improve spectrum utilization by sharing hardware resources and spectrum resources for communication and detection.

[0003] Currently, there are many challenges for terahertz communication detection integration technology. First of all, terahertz detection requires ultra-high bandwidth to improve detection accuracy. Therefore, an analog-to-digital converter (ADC) with an ultra-high sampling rate is required at the receiving end to avoid signal distortion. Obviously, its manufacturing difficulty is large and the cost is very high. The current research on terahertz communication detection integration is still in the exploratory stage. When the communication and detection functions are carried out simultaneously, mutual interference will occur and the system performance will deteriorate. Therefore, there is an urgent need to propose a new solution for the terahertz communication detection integration system to solve the above problems. Summary of the Invention

[0004] An embodiment of the present application provides a target detection method. By using a multi-band quasi-perfect (MS-QP) sequence with multiple sub-bands as the transmitted communication cooperation sequence signal, relying on the multiple sub-bands of the MS-QP sequence, a relatively wide bandwidth is divided into multiple narrow bands. Among them, each sub-band corresponds to a narrow band. At the same time, narrow-band Zadoff-Chu (ZC) sequences are transmitted on each sub-band, thereby ensuring that the communication cooperation sequence signal has strong autocorrelation characteristics. So that when the echo signal generated by the communication cooperation sequence signal is received, the radar detection component can be determined according to the echo signal, and the target can be detected by correlating the detection sequence component and the radar detection component. Since the transmitted communication cooperation sequence signal divides the relatively wide bandwidth into multiple narrow bands, a high-cost high-sampling ADC can be avoided when receiving the echo signal, thereby reducing the hardware cost.

[0005] In a first aspect, a target detection method is provided. The method includes: transmitting a communication cooperation sequence signal. Among them, the communication cooperation sequence signal may include a detection sequence component. The detection sequence component is an MS-QP sequence with multiple sub-bands, and each sub-band may include a narrow-band ZC sequence. After that, the echo signal of the communication cooperation sequence signal can be received, and a fast Fourier transform (FFT) is performed on the echo signal to determine the radar detection component of the echo signal in the frequency domain. After that, the detection sequence component and the radar detection component are correlated to determine at least one correlation peak and the time delay information corresponding to at least one correlation peak. Then, at least one target and the target distance corresponding to each target can be determined according to at least one correlation peak and the time delay information corresponding to at least one correlation peak. In the present application, each sub-band of the MS-QP sequence with multiple sub-bands includes a narrow-band ZC sequence, thereby ensuring that the transmitted communication cooperation sequence signal can have good autocorrelation characteristics for target detection. At the same time, through multiple sub-bands, the large bandwidth occupied by the transmitted information is divided into multiple narrow bands, so that a low-sampling-rate ADC can be used when receiving the echo signal to reduce the hardware cost.

[0006] In a possible implementation manner, the method may further include: performing phase adjustment on each ZC sequence in the MS-QP sequence by using an optimal phase factor set. The present application can also perform phase adjustment on each ZC sequence in the MS-QP sequence to reduce the peak-to-average power ratio of the signal.

[0007] In a possible implementation manner, the ZC sequence may include: a sequence length L m and a root index p. Among them, the root index p satisfies L mDenote the length of the ZC sequence on the m-th sub-band, where m is a positive integer greater than or equal to 2. By optimizing the root index of the ZC sequence in this application, the Doppler frequency shift problem can be effectively reduced, so that the high sidelobes generated by Doppler during target detection can be concentrated as much as possible near the correlation peak, thereby avoiding misjudgment of the target.

[0008] In a possible implementation, the method may further include: there is a frequency-domain guard interval (GI) between the ZC sequences of every two adjacent sub-bands. By setting a frequency-domain guard interval between adjacent sub-bands in this application, mutual interference between different sub-bands can be avoided, and data loss at the sub-band connection part during decoding can be avoided.

[0009] In a possible implementation, the communication cooperation sequence signal further includes: a data symbol component. The data symbol component may include data sequences of multiple sub-bands, and the data sequences on each sub-band are transmitted at multiple zero-frequency points on the sub-band. The zero-frequency points are obtained by M retransmissions of the ZC sequence on the sub-band in the time domain. By retransmitting the ZC sequence on each sub-band multiple times in this application, multiple zero-frequency points can appear in the frequency domain, and the digital symbol component is transmitted at the zero-frequency points, so that this application can simultaneously implement the two functions of communication and detection, and there will be no interference between them.

[0010] In a possible implementation, the method may further include: performing corresponding phase adjustment on the data sequence transmitted on each sub-band. This application can also perform corresponding phase adjustment on the data sequence so that it can be transmitted at the corresponding zero-frequency point.

[0011] In a possible implementation, determining at least one target and at least one target distance according to at least one correlation peak and the delay information corresponding to at least one correlation peak may include: at least one correlation peak corresponds to at least one target one by one, so that the corresponding target can be determined through the correlation peak. And, determine the target distance of the target corresponding to each correlation peak according to the delay information corresponding to at least one correlation peak.

[0012] In a second aspect, a target detection device is provided. The device includes: a transmitter for transmitting a communication cooperation sequence signal, where the communication cooperation sequence signal includes a detection sequence component, and the detection sequence component is an MS-QP sequence with multiple subbands, and each subband includes a narrowband ZC sequence; a receiver for receiving an echo signal of the communication cooperation sequence signal; a processor coupled to a memory and configured to read and execute instructions stored in the memory; when the processor runs, it executes the instructions such that the processor is configured to perform a fast Fourier transform on the echo signal to determine a radar detection component of the echo signal in the frequency domain; perform correlation on the detection sequence component and the radar detection component to determine at least one correlation peak and delay information corresponding to at least one correlation peak; and determine at least one target and at least one target distance according to at least one correlation peak and delay information corresponding to at least one correlation peak. In this application, each subband of the MS-QP sequence with multiple subbands includes a narrowband ZC sequence, thereby ensuring that the transmitted communication cooperation sequence signal can have good autocorrelation characteristics for target detection. At the same time, through multiple subbands, the large bandwidth occupied by the transmitted information is divided into multiple narrowbands, so that a low-sampling-rate ADC can be used when receiving the echo signal to reduce the hardware cost.

[0013] In a possible implementation, the processor is further configured to: perform phase adjustment on each ZC sequence in the MS-QP sequence using an optimal phase factor set. This application can also perform phase adjustment on each ZC sequence in the MS-QP sequence to reduce the peak-to-average power ratio of the signal.

[0014] In a possible implementation, the ZC sequence includes: a sequence length L m and a root index p, where the root index p satisfies L m represents the length of the ZC sequence on the m-th subband, and m is a positive integer greater than or equal to 2. By optimizing the root index of the ZC sequence in this application, the Doppler frequency shift problem can be effectively reduced, so that the high sidelobes generated by Doppler during target detection can be concentrated near the correlation peak as much as possible, thereby avoiding misjudgment of the target.

[0015] In a possible implementation, the processor is further configured to: there is a frequency domain guard interval between the ZC sequences of every two adjacent subbands. By setting a frequency domain guard interval between adjacent subbands in this application, mutual interference between different subbands can be avoided, and data loss at the subband connection part during decoding can be avoided.

[0016] In a possible implementation, the communication cooperation sequence signal further includes: a data symbol component. The data symbol component includes data sequences of multiple subbands, and the data sequences on each subband are transmitted at multiple zeroed frequency points on the subband. The zeroed frequency points are obtained by performing M retransmissions of the ZC sequence on the subband in the time domain. In this application, by performing multiple retransmissions of the ZC sequence on each subband, multiple zeroed frequency points can appear in the frequency domain, and digital symbol components are transmitted at the zeroed frequency points, so that this application can simultaneously implement the two functions of communication and detection, and there will be no interference between them.

[0017] In a possible implementation, the processor is further configured to: perform corresponding phase adjustment on the data sequences transmitted on each subband. This application can also perform corresponding phase adjustment on the data sequences so as to be transmitted at the corresponding zeroed frequency points.

[0018] In a possible implementation, the processor is further configured to: at least one correlation peak corresponds to at least one target one by one, so that the corresponding target can be determined through the correlation peak. And, determine the target distance of the target corresponding to at least one correlation peak according to the delay information corresponding to at least one correlation peak.

[0019] In a third aspect, a computer-readable storage medium is provided. Instructions are stored in the computer-readable storage medium. When the instructions run on a terminal, the terminal is enabled to execute any one of the methods in the first aspect.

[0020] In a fourth aspect, a computer device including instructions is provided. When it runs on a terminal, the terminal is enabled to execute any one of the methods in the first aspect.

[0021] In a fifth aspect, a computer program product including instructions is provided. When it runs on a computer, the computer is enabled to execute any one of the methods in the first aspect.

[0022] This application discloses a target detection method and device. By using the MS-QP sequence with multiple subbands as the transmitted communication cooperation sequence signal, it not only perfectly inherits the autocorrelation characteristics of the ZC sequence, but also can divide the broadband required for communication into multiple narrowbands for transmission, so that a high-cost high-sampling ADC can be avoided when receiving the echo signal and the hardware cost can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of an application scenario provided by an embodiment of this application;

[0024] Figure 2 It is a schematic structural diagram of a communication and detection integration device provided by an embodiment of this application;

[0025] Figure 3 Schematic diagram of a communication detection integration device provided by an embodiment of the present application;

[0026] Figure 4 Flowchart of a communication detection integration method provided by an embodiment of the present application;

[0027] Figure 5 Schematic diagram of spectrum shifting of a transmitting device provided by an embodiment of the present application;

[0028] Figure 6 Another schematic diagram of spectrum shifting of a transmitting device provided by an embodiment of the present application;

[0029] Figure 7 Schematic diagram of time-domain representation of an MS-QP sequence provided by an embodiment of the present application;

[0030] Figure 8 Schematic diagram of frequency-domain representation of an MS-QP sequence provided by an embodiment of the present application;

[0031] Figure 9 Schematic diagram of autocorrelation characteristics of a narrowband ZC sequence;

[0032] Figure 10 Schematic diagram of autocorrelation characteristics of an MS-QP sequence provided by an embodiment of the present application;

[0033] Figure 11 Schematic diagram of a multi-subband communication system provided by an embodiment of the present application;

[0034] Figure 12 Schematic diagram of the structure of an MS-QP sequence provided by an embodiment of the present application;

[0035] Figure 13 Schematic diagram of the spectrum of an MS-QP sequence after time-domain expansion provided by an embodiment of the present application;

[0036] Figure 14 Schematic diagram of a single-subband communication cooperative sequence signal provided by an embodiment of the present application;

[0037] Figure 15 Schematic diagram of range profile affected by hardware mismatch;

[0038] Figure 16 Schematic diagram of range profile affected by Doppler frequency shift;

[0039] Figure 17 Schematic diagram of the autocorrelation change curve of a narrowband ZC sequence provided by an embodiment of the present application;

[0040] Figure 18 Schematic diagram of range profile before root index optimization provided by an embodiment of the present application;

[0041] Figure 19 Schematic diagram of the distance image after the root index optimization provided by the embodiment of the present application;

[0042] Figure 20 Schematic diagram of the construction of the echo signal of the receiving device provided by the embodiment of the present application;

[0043] Figure 21 Schematic diagram of the signal processing of the receiving device in the m-th sub-band provided by the embodiment of the present application;

[0044] Figure 22 Schematic diagram of the determination of the DRM of the echo signal provided by the embodiment of the present application;

[0045] Figure 23 Schematic diagram of the single-subband spectrum of the communication cooperation sequence signal provided by the embodiment of the present application;

[0046] Figure 24 Schematic diagram of the signal waveform of the DRM generation process provided by the embodiment of the present application;

[0047] Figure 25 Schematic diagram of the comparison of the ranging performance of the sequence provided by the embodiment of the present application;

[0048] Figure 26 Schematic diagram of the comparison of the speed measurement performance of the sequence provided by the embodiment of the present application;

[0049] Figure 27 Schematic diagram of the relationship between the frequency domain occupancy ratio and the ranging performance provided by the embodiment of the present application;

[0050] Figure 28 Schematic diagram of the relationship between the frequency domain occupancy ratio and the speed measurement performance provided by the embodiment of the present application;

[0051] Figure 29 Another schematic diagram of the communication detection integrated device provided by the embodiment of the present application;

[0052] Figure 30 Another schematic diagram of the communication detection integrated device provided by the embodiment of the present application. Specific implementation manners

[0053] Next, the technical solutions in the embodiments of the present application will be described with reference to the accompanying drawings in the embodiments of the present application.

[0054] The present application is mainly applied to the scenario of target detection, such as Figure 1As shown, the transmitting device 110 of the integrated communication and detection device 100 emits a transmission signal. After traveling a certain distance, the transmission signal encounters the target 200, and then the transmission signal is reflected by the target 200 to form an echo signal. The echo signal travels the same distance again and is received by the receiving device 120 of the integrated communication and detection device 100. By analyzing the received echo signal through the receiving device 120, it is determined whether there is a target 200 and the distance between the target 200 and the integrated communication and detection device 100. Of course, Figure 1 The integrated communication and detection device 100 shown in is an integrated device that includes a transmitting device 110 and a receiving device 120. In other scenarios, the transmitting device 110 and the receiving device 120 can also be two independent devices. Obviously, when the transmitting device 110 and the receiving device 120 are taken as a whole, they can share the same set of hardware resources, thereby reducing the manufacturing cost. In this scenario, the target 200 is illustrated by taking a certain user as an example. It can be understood that the target 200 can also be any other object, and the present application does not make any limitations.

[0055] Under normal circumstances, in order to reduce the manufacturing cost, in most cases, the integrated communication and detection device 100 with a transmitting device 110 and a receiving device 120 is used for communication and detection. A communication and detection cooperation system is usually run on the integrated communication and detection device 100 to perform communication and detection simultaneously. For a communication and detection cooperation system using terahertz, the transmitting device 110 and the receiving device 120 for communication and detection share a set of hardware resources. The positions of the transmitting device 110 and the receiving device 120 can be approximately regarded as the same, and they share a local oscillator (which can be abbreviated as LO). It can be understood that in some cases, the transmitting device 110 can also be called a signal transmitting end, and the receiving device 120 can also be called a radar detection end. In some examples, the LO can use an inductor capacitor (LC) oscillator, etc. Since the attenuation of terahertz signal propagation is relatively large, Figure 1 The scenario shown usually considers short-distance target detection. In order to effectively counteract the propagation attenuation, the communication and detection cooperation system usually can use a high-gain directional antenna for signal transmission to generate an extremely narrow beam, so that the line-of-sight link can be considered and the multipath effect can be ignored in this scenario. Among them, the line-of-sight link means the signal transmitted between the integrated communication and detection device 100 and the straight-line distance of the target 200, and the echo signal transmitted from other directions after the transmitted signal is reflected by the target 200 is ignored.

[0056] It can be understood that although the beam of the transmitted signal is very narrow, in some scenarios, the communication detection and cooperation system can still detect one or more targets. For example, in a holographic video conference, in order to track the changes in the human body movement posture, human body posture detection is required. Among them, different body parts can be regarded as different targets. Just as Figure 1 In [reference], the communication detection integrated device 100 transmits a transmitted signal. For Figure 1 the user 200 shown on the right in [reference], they can hold a terminal device to receive the transmitted signal. Of course, after passing through the user 200, part of the transmitted signal will be reflected and form an echo signal, and this echo signal will be received by the communication detection integrated device 100. After receiving the echo signal, the communication detection integrated device 100 can analyze the echo signal to achieve the detection of the user's posture and movement.

[0057] Such as Figure 2 As shown, it shows a schematic structural diagram of a communication detection integrated device. It can be seen that the communication detection integrated device 100 may include a transmitting device 110 and a receiving device 120. Among them, in the transmitting device 110, first, the encoding and modulation module 111 generates a baseband signal to be transmitted, and sends the baseband signal to the digital-to-analog converter (DAC) 112 to convert the digital baseband signal into an analog signal. After the converted analog signal is up-converted by the up-conversion module 113 to increase the frequency to the terahertz band, and then amplified by the high-power amplifier 114 to increase the transmission power to form a transmitted signal, and finally the transmitted signal is sent out through the transmit antenna (TX ANT) 115. At the same time, the receiving device 120 in the communication detection integrated device 100 can receive the echo signal formed after the transmitted signal is reflected by the target 200 through the receive antenna (RX ANT) 121. Then, the received echo signal is processed by the low-noise amplifier 122, and then the frequency of the processed echo signal is reduced by the down-conversion module 123, and then the echo signal with the reduced frequency is converted from the frequency domain to the time domain through the ADC, so as to form a baseband signal corresponding to the echo signal. The receiving device 120 can input the baseband signal corresponding to the echo signal into the radar detection module 125 for target detection, and input the baseband signal corresponding to the echo signal into the demodulation and decoding module 126 to obtain the transmitted information.

[0058] For the waveforms of the transmitted signal and the echo signal, most of the traditional detection waveforms can be classified into orthogonal frequency division multiplexing (OFDM) waveforms and single-carrier transmission waveforms. In the field of communication and detection integration, a relatively low-frequency communication and detection cooperation system is usually adopted at present. For example, OFDM signals, cyclic prefixed single carrier (CP-SC), preamble sequences in data frame structures, and direct sequence spread spectrum signals are used for communication and detection cooperation.

[0059] The advantage of the OFDM waveform is that it can be used for both communication and detection at the same time, and the maximum likelihood-based distance / velocity detection method has good robustness to Doppler frequency shift. When using an OFDM symbol as the transmitted signal, its frequency domain can be expressed as A[k], where k = 1, 2, …, N’, and N’ is a positive integer, which can represent the number of subcarriers of the OFDM symbol. A[k] is the data symbol on the k-th subcarrier. It can be understood that the value of A[k] can be selected from a pre-set constellation diagram according to the modulation scheme. After A[k] undergoes an inverse fast Fourier transformation (IFFT), the time-domain representation a[n’] can be obtained, where n’ = 1, 2, …, N’, and n’ is the sampling point sequence number in the time domain. The number of sampling points can be the same as the number of subcarriers. It can be understood that the value ranges of n’ and k are the same. Then a[n’] is sent out through the transmitting antenna. The time-domain signal of this OFDM is sent to the communication receiving end. Part of the energy is received by the communication receiving end for signal demodulation, while the other part is reflected by the surface of the communication receiving end, forming an echo signal and transmitted to the transmitting end. Among them, the communication receiving end can be, for example Figure 1The target 200 therein. When the transmitting end adopts a communication and detection integrated device, it can be received by a co-located receiving device (or called the radar receiving end), and the received echo signal can be expressed as y[n']. For the receiving device, two detection algorithms are usually available to detect y[n']. The first method is that the receiving device and the transmitting device in the communication and detection integrated device share a set of hardware, so the receiving device knows the transmitted a[n']. Therefore, by correlating y[n'] with a[n'], a range profile can be obtained. Then, analyze the position of the correlation peak in the range profile and estimate the target distance. The operation of this detection algorithm is relatively simple, but the autocorrelation characteristic of a[n'] is often not ideal. Only when the frequency-domain symbols of the OFDM waveform are constant modulus, the time-domain sequence has an ideal autocorrelation characteristic. Especially when a[n'] is random, its autocorrelation characteristic cannot be guaranteed accordingly, thus affecting the improvement of detection performance. The second method is to perform a discrete Fourier transform (DFT) on y[n'] to obtain Y[k] in the frequency domain. Then, according to the frequency-domain response of the channel impulse response can be obtained. After that, perform an inverse discrete Fourier transform (IDFT) on I[k] to obtain the range profile for radar detection. For this method, by comparing the received signal with the transmitted signal on each sub-band, the shape of the range profile is no longer affected by the randomness of the transmitted signal. However, since the method of dividing by the transmitted signal when calculating the frequency-domain response will cause noise amplification, there are certain limitations on the detection performance at low signal-to-noise ratios. For OFDM signals, their peak-to-average power ratio is relatively high, and serious nonlinear effects will occur after terahertz power amplification. For OFDM systems in the terahertz band, their bandwidth is large, so an ADC with an ultra-high sampling rate is required for sampling, which obviously has high requirements for hardware.

[0060] For single-carrier signals, their peak-to-average power ratio is usually relatively low, which can effectively reduce the nonlinear effect of the power amplifier and ensure better output power. Among them, CP-SC is a single-carrier signal with a cyclic prefix (CP). In some current solutions, a continuous W' group of traditional CP-SC signals is used as the transmitted signal, and the data part of each group of signals can be denoted as d w’ [n"], where w' = 0, 1,..., W' - 1, n" = 0, 1,..., N" - 1, and W' and N" are positive integers. N" can represent the number of data in each group of signals, and d w’ [n"] represents the n"th data in the wth group. Among them, each group of signals d w’[n"] can be modulated using a preset constellation diagram. For example, quadrature phase-shift keying (QPSK) can be used for modulation. When the W'-group CP-SC signals are modulated, they can be used as transmission signals and sent out by the transmitting antenna for the target to receive. It can be understood that a part of the energy of the transmission signal is received by the target and the signal is demodulated. At the same time, another part of the energy is reflected by the target surface to form an echo signal. For the echo signal, it can be received by the receiving device at the same position as the transmitting device, and the received echo signal can be expressed as y w’ [n"]. In order to detect the target distance and the relative moving speed of the target, the receiving device performs a cyclic correlation of length N" on each received data block y[n"] and the corresponding transmitted data d[n"] to obtain W' groups of correlation results of length N", which can be denoted as r(n", w'). Then, a Z-point FFT can be performed on the W' points corresponding to each correlation position. In some examples, Z can usually take the value of qW', where q is a positive integer. After the FFT, a range-doppler matrix (RDM) can be obtained, which can be denoted as R(n", k'). It can be understood that the value range of k' is the same as that of w'. And the maximum value corresponding to the horizontal and vertical coordinates is determined by traversing R(n", k'). And the target distance and the relative moving speed of the target are obtained by simple conversion of the coordinates. In some examples, common single-carrier transmission waveforms can include linear frequency modulated (LFM) signals, pseudo-random spreading codes, perfect sequences, etc. Among them, the pseudo-random spreading code can be, for example, the longest linear shift register sequence (abbreviated as m-sequence), Gold sequence, etc. The perfect sequence can be, for example, the ZC sequence, Frank sequence, etc. It can be understood that when the CP-SC signal is directly used for radar detection, the implementation is relatively simple and the peak-to-average ratio is low. However, due to the randomness of the modulation symbols, the good autocorrelation characteristics of the sequence cannot be guaranteed, resulting in limited detection performance.

[0061] In some other current solutions, when a single - carrier preamble sequence is used as the transmitted signal, its data - frame structure includes a short training field (STF) and a channel estimation field (CEF). In communication, the STF can be used for synchronization and frequency - offset estimation, and the CEF can be used for channel estimation. The single - carrier preamble sequence can be composed of multiple groups of Golay complementary sequences with good autocorrelation characteristics, so it is suitable for radar detection. In some examples, the transmitting device transmits the transmitted signal to the target through the transmitting antenna. A part of the energy of the transmitted signal is received by the target and demodulated, and at the same time, another part of the energy is reflected by the target surface to form an echo signal. For the echo signal, it can be received by the receiving device at the same position as the transmitting device, and target detection is performed based on the preamble sequence in the echo signal. During the detection process, the STF and CEF can be regarded as a whole, and the cross - correlation between the preamble sequence of the transmitted signal and the preamble sequence of the received signal is calculated. Whether there is a target and the target echo delay are determined by finding the cross - correlation peak, and the target distance is further calculated based on the target echo delay. For example, the target distance is determined according to the target echo delay and the speed of light. At the same time, the carrier - frequency offset estimation method of the wireless local area network (WLAN) can also be used for estimation to determine the relative moving speed of the target. The specific implementation process can refer to the existing methods and will not be elaborated here. However, since the length of the single - carrier preamble sequence is usually short, it cannot resist the extremely high path loss of the terahertz channel. In other words, the single - carrier preamble sequence cannot resist the extremely low signal - to - noise ratio of the receiving device.

[0062] Of course, in some other solutions, the m - sequence can also be used to directly spread - spectrum the single - carrier communication signal. Among them, the single - carrier communication signal can be, for example, a phase - shift keying (PSK) symbol sequence. In one example, a sufficiently large spreading ratio can be set so that the spread - spectrum sequence can have the good autocorrelation characteristics of the pseudo - random code m - sequence. For example, assume that the transmitted signal is modulated using U - order PSK. U represents the order of PSK, which is generally a positive integer. Among them, assume that the length of the data symbol before spreading is N”, and the corresponding bit of the i - th data symbol can be denoted as u is a 0 / 1 bit. Assume that the length of the m - sequence is L’, or the spreading ratio is L’, then the l - th bit can be denoted as h’ l . Among them, L’ can be a positive integer, and l = 1, 2,..., L’. Then, each element h l in the m - sequence can be used for modulo - 2 addition with each element in , that is, The obtained data stream is passed through a modulator to obtain L' M-PSK symbols after direct-sequence spread spectrum. Similarly, the above-mentioned spreading operation can be performed on each data symbol to generate a direct-spread sequence signal with a length of N"L', which is used as the transmitted signal. In some examples, the transmitting device transmits the transmitted signal to the target through the transmitting antenna. A part of the energy of the transmitted signal is received by the target and demodulated, and at the same time, another part of the energy is reflected by the target surface to form an echo signal. For the echo signal, it can be received by the receiving device at the same position as the transmitting device, and target detection is performed based on the echo signal. The corresponding process can refer to the existing time-domain-based method, which will not be elaborated herein. Obviously, the spread-spectrum signal has good autocorrelation characteristics, but when the spreading ratio is set relatively high, the communication rate will be reduced. At the same time, it will also cause the code length to be too large and further aggravate the influence of the Doppler frequency shift.

[0063] As can be seen from the above solution, in the terahertz communication detection collaborative system, when the communication and detection functions are performed simultaneously, the communication signal and the detection signal (or radar signal) may interfere with each other, seriously affecting the overall performance of the system. At the same time, in order to meet the high resolution of detection, the terahertz communication detection collaborative system needs to use an ultra-high signal bandwidth, so the receiving device also needs an extremely high sampling rate, resulting in great difficulty and high cost in manufacturing the ADC.

[0064] Therefore, the present application provides a target detection method. By using an MS-QP sequence with multiple subbands as the transmitted communication collaborative sequence signal, each subband can include a narrowband ZC sequence. After receiving the echo signal formed by reflecting the communication collaborative sequence signal, the echo signal is subjected to FFT to determine the radar detection component of the echo signal in the frequency domain. Correlation is performed on the detection sequence component and the radar detection component to determine at least one correlation peak and the time delay information corresponding to at least one correlation peak, and at least one target and the target distance corresponding to each target are determined. The communication collaborative sequence signal transmitted by the present application can ensure good autocorrelation characteristics for target detection. At the same time, through multiple subbands, the large bandwidth occupied by the transmitted information is divided into multiple narrowbands, so that a low-sampling-rate ADC can be used when receiving the echo signal to reduce the hardware cost.

[0065] Next, the technical solutions in the embodiments of the present application will be described in detail with reference to the accompanying drawings in the embodiments of the present application.

[0066] Figure 3 It is a schematic diagram of a communication detection integrated device provided by an embodiment of the present application.

[0067] Such as Figure 3As shown, the present application provides a communication and detection integrated device 300. The communication and detection integrated device 300 can be applied to signal transmission and reception scenarios during communication and detection, and may include: one or more processors 301, one or more memories 302, a transmitter 303, a receiver 304, one or more antennas 305, and a bus 306. The processor 301, memory 302, transmitter 303, and receiver 304 in the communication and detection integrated device 300 can establish a communication connection through the bus 306. The transmitter 303 and the receiver 304 can also be connected to the antenna 305, so that the transmitter 303 can send transmission data through the antenna 305, and the receiver 304 can receive echo signals through the antenna 305. Of course, in some examples, the transmitter 303 and the receiver 304 can share a set of hardware devices. It can be understood that the transmitter 303 is Figure 1 and Figure 2 the transmission device 110 in Figure 1 and Figure 2 the receiving device 120 in

[0068] It can be understood that the structure illustrated in the embodiments of the present invention does not constitute a specific limitation on the communication and detection integrated device 300. The communication and detection integrated device 300 may include more or fewer components than those illustrated, or combine certain components, or split certain components, or have different component arrangements. The illustrated components can be implemented in hardware, software, or a combination of software and hardware.

[0069] Among them, the processor 301 can be a processor with an architecture such as an advanced reduced instruction set computing machine (ARM), X86, or a microprocessor without interlocked piped stages (MIPS). The processor 301 may include one or more processing units, for example: an application processor (AP), a modulation and demodulation processor, a GPU, an image signal processor (ISP), a controller, a video codec, a digital signal processor (DSP), a baseband processor, and / or a neural-network processing unit (NPU), etc. Among them, different processing units can be independent devices or integrated in one or more processors.

[0070] The memory 302 is used to store instructions and data. In some embodiments, the memory 302 is a cache memory. This memory 302 can save the instructions or data that the processor 301 has just used or recycled. If the processor 301 needs to use the instruction or data again, it can be directly called from the memory 302. This avoids repeated accesses, reduces the waiting time of the processor 301, and thus improves the efficiency of the system. In one example, the memory 302 may include a memory, in which an operating system, an image file, etc. can be stored. The memory 302 may also include an auxiliary memory or an external memory, such as a non-removable memory or a removable memory card, etc.

[0071] Among them, the internal memory can be used to store computer-executable program codes, and the executable program codes include instructions. The internal memory may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one magnetic disk storage device, a flash memory device, a universal flash storage (UFS), etc. The processor 301 executes various functional applications and data processing of the communication detection integrated device 300 by running the instructions stored in the memory.

[0072] It can be understood that the communication detection integrated device 300 may be a terminal device, such as including but not limited to a mobile phone, a smart TV, a smart speaker, a wearable device, a tablet computer, a desktop computer, a handheld computer, a laptop computer, an ultra-mobile personal computer (UMPC), a netbook, a personal digital assistant (PDA), a laptop, a mobile computer, an augmented reality (AR) device, a virtual reality (VR) device, an artificial intelligence (AI) device, a vehicle-mounted device, a smart home device, and / or a smart city device, etc., any terminal device or portable terminal device. Of course, in some other examples, the communication detection integrated device 300 may also be a network device, such as a wireless base station, a repeater, a network node, etc.

[0073] Figure 4 This is a flowchart of a communication detection integration method provided by an embodiment of the present application.

[0074] As Figure 4 shown, the present application also provides a communication detection integration method, and this method can be applied to Figure 3 the communication detection integrated device 300 shown. This method includes the following steps:

[0075] S401, transmit a communication cooperation sequence signal.

[0076] The transmitter 303 in the communication detection integrated device 300 transmits a communication cooperation sequence signal through the antenna 305. Among them, the communication cooperation sequence signal includes a detection sequence component. The detection sequence component is an MS-QP sequence with multiple subbands, and each subband corresponds to a narrowband ZC sequence.

[0077] In one example, in order to solve the problems of high sampling rate requirements, high ADC manufacturing cost and high difficulty in the terahertz communication detection cooperation system, the MS-QP sequence is constructed by means of the ZC sequence for the detection sequence component in the communication cooperation sequence signal. Since both the perfect sequence long code and short code have ideal autocorrelation characteristics, the perfect sequence is very suitable for target detection in the terahertz band. Therefore, the MS-QP sequence of this application is constructed by the ZC sequence, thus ensuring that the MS-QP sequence also has good detection performance.

[0078] For example, the MS-QP sequence can be constructed by using multiple narrowband ZC sequences. It can be understood that the construction of the MS-QP sequence can be realized by the processor 301. First, perform DFT on multiple narrowband ZC sequences to the frequency domain. Among them, each narrowband ZC sequence in the multiple narrowband ZC sequences can be the same or different. Then, shift and splice the spectra of the multiple narrowband ZC sequences. The spectrum of each narrowband ZC sequence constitutes multiple adjacent subbands and forms an ultra-wideband spectrum. It can be understood that each subband corresponds to a narrowband ZC sequence. Obviously, compared with the existing method, when the bandwidth required for the transmitted data is very wide, an ADC with a high sampling rate is required for sampling and receiving, and it is difficult and costly to construct a high-sampling-rate ADC. In this application, the large bandwidth required for the transmitted signal is divided into multiple narrowbands spliced together. Therefore, it is avoided to use an ADC with a high sampling rate for sampling and receiving during reception. Then, the processor 301 performs IDFT on the ultra-wideband spectrum to obtain the time-domain representation of the MS-QP sequence. Generally, in order to improve the ranging resolution of target detection, an ultra-high bandwidth is required when transmitting the transmitted signal. It can be understood that the higher the bandwidth of the transmitted signal, the higher the ranging resolution accuracy. Therefore, when the MS-QP sequence has an ultra-high signal bandwidth, the ranging resolution can be effectively improved.

[0079] In one example, in order to avoid interference between adjacent subbands during signal filtering, for every two adjacent subbands, that is, between the ZC sequences on adjacent subbands, a frequency-domain guard interval L is inserted during spectrum shifting and splicing G , so that there is a certain interval between two adjacent subbands in the frequency domain, avoiding interference between adjacent subbands.

[0080] For exampleFigure 5 shows a schematic diagram of spectral shifting of a transmitting device in hardware implementation, where b m [n] represents the narrowband ZC sequence on the m-th subband, m = 0, 1, …, M - 1, and M is a positive integer greater than or equal to 2. It can be understood that under some extreme conditions, such as when the bandwidth required to transmit information is very small, and only one subband in the MS-QP sequence contains a narrowband ZC sequence to complete data transmission, the value of M can be 1. b m [n] has a length of L m , f m represents the center frequency of the m-th subband. For each narrowband ZC sequence, its corresponding symbol interval is denoted as T m . x[n] represents the MS-QP sequence constructed by frequency-domain spreading, and its length is ML G +∑L m . Of course, it can be understood that if the frequency-domain guard interval L G is not set, the length can be ∑L m . For the MS-QP sequence constructed by frequency-domain spreading, its corresponding time-domain symbol interval can be denoted as T M , and Figure 5 the analog signal output by the transmitting device in m is denoted as x(t). It can be seen that the process of generating the analog signal x(t) can be, for each subband, first passing b [n] through a shaping filter and then converting the digital signal into an analog signal via a DAC. Among them, the shaping filter is mainly used to convert the clock rate of the signal from the symbol rate to the analog-to-digital (DA) sampling rate for subsequent processing in the DAC. For each subband, after being converted into an analog signal, spectral shifting is performed, that is, each subband in the figure is multiplied by m to achieve spectral shifting. Among them, j is the imaginary unit and t represents time. It can be understood that both f’ m and f m represent the center frequency of the m-th subband. Among them, f m is mainly used for calculation at discrete points in the digital domain, while f’

[0081] For example Figure 6 shows another schematic diagram of spectral shifting of a transmitting device. It can be seen that this method first performs different subbands bm [n] Through the shaping filter, spectral shifting is performed on the digital signals on each subband, that is, each subband in the figure is multiplied by a multiplier to achieve spectral shifting. After that, an adder is used to superimpose the digitally shifted signals to obtain the digital signal x[n] to be transmitted. Then, the digital signal x[n] is converted into an analog signal through a DAC, and the analog signal is boosted to the terahertz band, such as by multiplying with a multiplier to achieve boosting the analog signal to the terahertz band to obtain the transmitted signal x(t). Among them, f c can be expressed as the center frequency of the required bandwidth of the transmitted signal. Obviously, since this method performs spectral shifting and superposition on the digital signal side and then converts the digital signal into an analog signal through a DAC, Figure 6 the DAC shown needs to rely on a high-sampling DAC to complete the digital-to-analog conversion of the ultra-wideband signal. It can be understood that the time-domain symbol interval is T M . And relative to Figure 5 , it converts the digital signal into an analog signal through a DAC before performing spectral shifting. Therefore, Figure 5 the DAC in can be implemented by selecting multiple low-sampling DACs. At this time, the time-domain symbol interval is only T m .

[0082] In an example, the expression of the digital signal x[n] can be determined based on the methods provided by Figure 5 and Figure 6 . Among them, the digital signal x[n] is the above-mentioned MS-QP sequence. First, for the narrowband ZC sequence b m [n] can be expressed by formula 1.

[0083]

[0084] Among them, n''' is used to represent the serial number of the narrowband ZC sequence, n''' = 0, 1,..., L m - 1. exp represents the exponential function with e as the base, p m is the root index, L m can be odd and satisfies gcd(p m , L m ) = 1. gcd represents the greatest common divisor. It can be assumed that the frequency-domain representation of b m [n'''] is B m [k], where k = 0, 1,..., L m - 1. If considering setting a frequency-domain guard interval, the total length of the narrowband ZC sequence can be N = ML G + ∑L m . Then x[n] (n = 0, 1,..., N - 1) can be expressed as

[0085]

[0086] Wherein, n is used to represent the sequence number of the MS-QP sequence. Formula 2 can be further transformed into Formula 3.

[0087]

[0088] in,

[0089]

[0090] It can be understood that if the frequency domain guard interval is not set, then L in the above formula G It can be 0. Of course, when a frequency domain guard interval is set, although x[n] is composed of multiple narrowband ZC sequences, it is not a truly perfect sequence, but it still has good autocorrelation characteristics. This is because the sequence has a perfect autocorrelation characteristic, which is equivalent to the frequency domain amplitude spectrum of the sequence being a transverse mode. When the frequency domain guard interval set between adjacent subbands accounts for a lower proportion of the overall bandwidth occupied by the transmitted signal, the frequency domain amplitude spectrum of x[n] is closer to the transverse mode and the autocorrelation characteristic is better.

[0091] Figure 7 A schematic diagram of a time domain representation of an MS-QP sequence is shown. In which, each narrowband ZC sequence has a length of 1007, and a total of 4 subbands are set as an example. The time domain diagram corresponding to the generated MS-QP sequence x[n] is as follows Figure 7 As shown. It can be seen that the transverse mode characteristic is no longer satisfied in the time domain, and it still has a certain peak-to-average ratio. It can be understood that the peak-to-average ratio can be reflected by the jitter amplitude of the signal in the time domain. For example, the higher the peak-to-average ratio, the greater the signal amplitude jitter (it can also be called more severe). Figure 8 The schematic diagram of the frequency domain representation of a MS-QP sequence shown shows that in the frequency domain, the x[n] spectrum is composed of multiple narrowband ZC sequence spectra. Figure 8 Each box in the diagram shows the spectrum of a narrowband ZC sequence. Obviously, the spectrum of x[n] is close to the transverse mode, which means that x[n] has good autocorrelation characteristics. Among them, the amplitude value of the signal remains unchanged as the frequency changes, which indicates a transverse mode in this frequency band. It can be seen that due to the setting of the frequency domain protection interval, the amplitude value of x[n] will be 0 at some frequencies in the spectrum of x[n]. Therefore, the spectrum of x[n] is close to the transverse mode, but not a true transverse mode.

[0092] Figure 9 The diagram shows the autocorrelation characteristics of the narrowband ZC sequence. It can be seen that the narrowband ZC sequence has a perfect autocorrelation characteristic. Of course, this is also true for other perfect sequences. Figure 10shows the schematic diagram of the autocorrelation characteristics of the MS-QP sequence of the present application. It can be seen that the MS-QP sequence also has quasi-perfect autocorrelation characteristics. However, compared with the narrowband ZC sequence, small-amplitude side lobes will be generated near the main peak, such as Figure 10 has a small amplitude both when the time delay is close to 0 and at other non-zero times.

[0093] In other examples, by Figure 7 Since the above MS-QP sequence no longer satisfies the transverse mode characteristics of the narrowband ZC sequence, the MS-QP sequence can be further improved to reduce the peak-to-average power ratio of the signal. Considering that the phase-frequency characteristics of the MS-QP sequence basically do not affect its autocorrelation characteristics, the phase of the sequence can be adjusted to achieve the purpose of reducing the peak-to-average power ratio of the signal. For example, different phase factors can be multiplied on different subbands of the MS-QP sequence. In one example, a finite set can be preset, where contains multiple phase factors. For example, when the number of subbands is M, M phase factors can be preselected from the finite set as the phase factor set. All possible phase factor sets can be traversed from the finite set , and the peak-to-average power ratio of the MS-QP sequence using this phase factor set is calculated. The phase factor set with the smallest peak-to-average power ratio is selected as the optimal phase factor set. And the narrowband ZC sequences on each subband of the MS-QP sequence are phase-adjusted using this optimal phase factor set.

[0094] Assume that the phase factor of the m-th subband is Then formula 3 can be further expressed as formula 5

[0095]

[0096] where the phase factor satisfies:

[0097]

[0098] where E() represents the expectation, |||| represents the modulus, and argmin represents the value of when taking the minimum value .

[0099] Therefore, based on formula 5, formula 1 can also be equivalent to formula 7.

[0100]

[0101] Based on formula 5 and formula 7, where L m is the length of the m-th narrowband ZC sequence and is set to be odd, pm is the root index of the m-th narrowband ZC sequence and satisfies gcd(p m , L m ) = 1. At the same time, combining with Formula 6 to obtain an MS-QP sequence with a smaller peak-to-average power ratio.

[0102] Of course, in some examples, the above-mentioned MS-QP sequence can not only be applied to the communication detection cooperation system that supports high-precision target detection in the set-top box system, but also be compatible with existing multi-service and multi-carrier communication systems, such as Figure 11 a schematic diagram of a multi-subband communication system shown. It can be seen that the structure of this multi-subband communication system is similar to that of the MS-QP sequence. The required frequency band can be divided into multiple subbands, such as M subbands. And a frequency-domain guard interval is inserted between two adjacent subbands. Different data services can be assigned to different subbands. For example, service 1 is configured for subband 1, service 2 is configured for subband 2, etc. It can be understood that the structure of the MS-QP sequence can be as Figure 12 shown, different from Figure 11 that, for each subband, instead of configuring the corresponding service, each narrowband ZC sequence is configured.

[0103] However, as the MS-QP sequence shown in Figure 12 , when it needs to transmit data for communication, that is, combining Figure 11 with Figure 12 , it can only be realized by time-division duplex, resulting in extremely low efficiency. Therefore, in some examples, the above MS-QP sequence can be further improved so that the transmitted communication cooperation sequence signal can support both target detection and communication and be interference-free with each other.

[0104] Therefore, in some examples, the communication cooperation sequence signal can also include a data symbol component. In other words, the data symbol component can also be embedded into the MS-QP sequence to form a communication cooperation sequence signal. Among them, the data symbol component includes data sequences of multiple subbands.

[0105] For example, the narrowband ZC sequence on each subband in the MS-QP sequence can be repeatedly transmitted M' times, then it is expanded to M' times the original length in the time domain. For each subband, the length of the transmitted sequence is L m M', and the time-domain expanded sequence can be denoted as b e,m [n]. Among them, M' is a positive integer greater than or equal to 2. The subscript e is used to represent expansion. After performing L e,m M'-point DFT on b m [n], there is only at M'k (k = 0, 1,..., L mThere is a value at the frequency point (sub - carrier) of (-1), and the values of the remaining frequency points are all 0. Of course, the value at the M'k frequency point is determined according to the narrow - band ZC sequence, so it can be 0 or any other arbitrary value. For the frequency points other than the M'k frequency point, they can be called zero - setting frequency points. These zero - setting frequency points can be used to modulate information, that is, for transmitting data, such as transmitting a data sequence. Figure 13 Fig. Figure 13 shows a schematic diagram of the spectrum of the MS - QP sequence after time - domain expansion. This figure is drawn with the narrow - band ZC sequence on a certain sub - band after M' = 2 - fold time - domain expansion as an example. It can be seen that before the time - domain expansion of the narrow - band ZC sequence, there are almost no frequency points with an amplitude of 0. Even if there are some frequency points with an amplitude of 0, there is still other data transmitted at that frequency point. For example, as shown by the solid line, the amplitude of some solid lines is 0, but there is still a situation with an amplitude of 1 at the frequency point with an amplitude of 0. When the narrow - band ZC sequence is repeatedly transmitted in the time domain, the obtained time - domain - expanded narrow - band ZC sequence is shown as a dotted line, and there will be multiple frequency points with a frequency of 0, that is, zero - setting frequency points. Among them, the zero - setting frequency points are, for example, Figure 13 the positions circled by the circles in Fig. Figure 13 . At the same time, there will be no other transmitted data at such zero - setting frequency points. Therefore, such zero - setting frequency points can be used to transmit a data sequence. Obviously, if a data sequence is transmitted at the zero - setting frequency point, it can ensure that the waveforms of the data symbol component and the detection sequence component are orthogonal to each other, thus avoiding mutual interference.

[0106] It can be understood that the more times the narrow - band ZC sequence is repeatedly transmitted in the time domain, the more corresponding zero - setting frequency points there are. It can be understood that the non - zero - setting frequency points on a certain sub - band are only integer multiples of M'.

[0107] In some examples, the data sequence can be a PSK symbol vector, and the length of the PSK symbol transmitted on a certain sub - band can be the same as the length of the narrow - band ZC sequence on that sub - band, that is, the length is L m . Therefore, the PSK symbol vector transmitted on the m - th sub - band can be denoted as S i’，m = [s i’，m [0], s i’，m [1],..., s i’，m [L m - 1]], where i' = 1, 2,..., M' - 1. In order to make S i’，m fall on the frequency point of M'k + i' (k = 0, 1,..., L m - 1), a data sequence with a length of L m M' can be generated as follows. As Among them, g = 1, 2,..., M' - 1. After that, can be combined with b e，m[n] is superimposed to achieve simultaneous transmission with the detection sequence component.

[0108] For example, Equation 8 shows that is superimposed with b e，m [n] to obtain the communication cooperation sequence signal after superposition

[0109]

[0110] where n”” = 0, 1,..., L m M'-1. α e，m and α i’，m are power distribution factors and can be preset.

[0111] Figure 14 This is a schematic diagram of a single sub-band communication cooperation sequence signal provided by an embodiment of the present application. It can be understood that Figure 14 only shows the generation process of the communication cooperation sequence signal on a certain sub-band. For each sub-band, the communication cooperation sequence signal on each sub-band can be generated by referring to the method shown in this figure. Thus, a communication cooperation sequence signal is formed For each sub-band, the narrowband ZC sequence transmitted on this sub-band forms M' copies after M' retransmissions, such as narrowband ZC sequence copy 1, narrowband ZC sequence copy 2... narrowband ZC sequence copy M'. At the same time, for the data sequence, it can also be repeatedly transmitted M' times in the time domain, such as data sequence copy 1, data sequence copy 2... data sequence copy M'. Of course, in order to ensure that each data sequence copy can fall on the zeroing frequency point, it is necessary to perform corresponding phase adjustments on the repeatedly transmitted data sequence copies. For example, the data sequence copy is passed through phase adjustment and superimposed with the narrowband ZC sequence. Obviously, for the first data sequence copy, since M' = 1, M'-1 = 0, so no phase adjustment is required. When corresponding phase adjustments are made to different data sequence copies and superimposed with the corresponding narrowband ZC sequence copies, the communication cooperation sequence signal on this sub-band can be obtained.

[0112] Of course, in some examples, a cyclic prefix can also be added before the signal for the communication cooperation sequence signal on each sub-band, so as to be used for data demodulation by the receiver of the communication cooperation sequence signal.

[0113] In some examples, based on the shown in Equation 8

[0114]

[0115] Furthermore, according to Equation 4, Equation 10 can be further obtained.

[0116]

[0117] Wherein, L’ m = L m M’ is the length of the sequence after time-domain expansion. And according to Equation 6, Equation 11 can be further obtained.

[0118]

[0119] At this time, the communication cooperation sequence signal of the multi-subband Its spectral efficiency can be Its unit can be bit per second per hertz (bit / s / Hz), L is the PSK modulation order, and γ is the proportion of the cyclic prefix duration in the total duration of the sequence.

[0120] In some other examples, since the path loss of the terahertz signal is much higher than that of the low-frequency electromagnetic wave, the signal-to-noise ratio of the echo signal generated by the transmitted communication cooperation sequence signal is much lower than that of the radar in the millimeter-wave band. For example, when the distance between the target and the communication detection integrated device is 3 meters, the signal-to-noise ratio of the echo signal detected by the receiving device of the communication detection integrated device can be as low as -56.6 decibels (dB). Therefore, when transmitting the communication cooperation sequence signal in S401, cyclic repeated transmission can be performed, for example, using a multi-repeated frame structure of the communication cooperation sequence signal. Each frame can contain multiple word blocks, and each word block transmits a communication cooperation sequence signal, thereby overcoming the low signal-to-noise ratio situation in the signal transmission process. Obviously, through the design of the repeated frame structure, the related complex operations of transmitting long sequences are also avoided at the same time.

[0121] S402, receive the echo signal of the communication cooperation sequence signal.

[0122] The receiver 304 in the communication detection integrated device 300 receives the echo signal of the communication cooperation sequence signal through the antenna 305. It can be understood that when receiving the echo signal, only multiple band-pass filters are needed to separate the signals in each subband, so an ADC with a low sampling rate can be used for the acquisition of the echo signal.

[0123] Signals in the terahertz band are usually affected by hardware mismatches generated by the transmitter 303 and the receiver 304, and certain nonlinear mixing distortions are produced. It can be understood that, in addition to the DAC and ADC, since the terahertz frequency lies between microwaves and light, the manufacturing complexity of radio frequency front-end devices is relatively high, resulting in significant hardware mismatch problems in the transmitter 303 and the receiver 304. Among them, the hardware mismatch mainly includes the amplitude and phase imbalance of the in-phase / quadrature branches in the structures of the transmitter 303 and the receiver 304 for the terahertz band, that is, the in-phase / quadrature (I / Q) imbalance. At the same time, factors such as the phase noise generated by the transceiver local oscillator and the nonlinearity of the high-gain power amplifier will all cause the signal to generate nonlinear distortion and affect the terahertz communication performance and detection performance.

[0124] In one example, it can be assumed that the transmitter 303 has compensated for the I / Q imbalance and nonlinearity at the transmitting end. Therefore, the echo signal will only be affected by the phase noise and I / Q imbalance of the receiver 304. Of course, the echo signal may also be interfered by other clutter signals in addition to the noise generated by the device. Since the beam of the signaler using the terahertz band is usually narrow, the clutter interference received is small, making the clutter signal intensity relatively weak. Therefore, the clutter received in the echo signal can be jointly modeled with thermal noise as additive complex Gaussian white noise and regarded as an equivalent noise term. For the s[n] transmitted by the transmitting device, its symbol period can be T. s , assuming that the number of targets to be detected is Q’, and the echo delay of the q’-th target is τ. q , T. s , the corresponding channel fading coefficient is h. q’ , the normalized Doppler is denoted as u. q， is the target moving speed of the q’-th target, c is the electromagnetic wave propagation speed, and the I / Q imbalance coefficient is denoted as μ. I / Q and υ. I / Q , the phase noise of the transceiver local oscillator is denoted as θ(n), so the echo signal y[n] can be as shown in Equation 12.

[0125]

[0126] Among them, is conjugate to h. q’ , s. * [n] is conjugate to s[n].

[0127] For y[n], it will be affected by hardware mismatch and Doppler frequency shift, resulting in a decline in detection performance. Through simulation, it can be known that the influence of the I / Q imbalance coefficient on target detection is small and can thus be ignored. The reason is that usually the I / Q imbalance coefficient is denoted as μ.I / Q is approximately 1, while υ I / Q is approximately 0, and at the same time, the cross-correlation value between the conjugate sequence and the original sequence can be made smaller. Regarding phase noise, although the transmitter 303 and the receiver 304 share the local oscillator, due to the existence of echo delay, the transceiver phase noise cannot be completely canceled. However, it can be proven that the overall phase noise loaded on the signal will not accumulate infinitely over time, so only small side lobes will be generated near the main peak of the range image. Among them, the range image refers to the correlation function image of the transmitted signal and the echo signal, which is used for target detection and time delay estimation. Therefore, this application can ignore the hardware mismatch problem.

[0128] It can be understood that the y[n], s[n], s * [n], θ(n) and the n in can also be replaced by n''' in Formula 1 and n'' in Formula 8.

[0129] Figure 15 is a schematic diagram of a range image affected by hardware mismatch. It can be seen that when the time delay is 1000, a correlation peak appears. It can be understood that the correlation peak can also be called the main peak. And on both sides of the correlation peak, that is, when the time delay is around 1000, small side lobes appear.

[0130] On the other hand, since the signal using the terahertz frequency band has an extremely high carrier frequency, it will be significantly affected by the Doppler frequency shift. When the Doppler frequency shift is large and the echo signal is long, obvious range side lobes will be generated on the range image, and the amplitude of the correlation peak will be reduced. It can be understood that the reason is that energy is conserved. When side lobe energy appears in other time delay segments, the energy corresponding to the correlation peak will inevitably be affected and even shift. For example Figure 16 shows a schematic diagram of a range image affected by the Doppler frequency shift. It can be clearly seen that when the time delay is more than 4000, obvious side lobes appear, and obvious side lobes also appear at the position where the time delay is nearly 8000. Obviously, it is also particularly important to counter the Doppler frequency shift.

[0131] Therefore, in some examples, the communication cooperation sequence signal in S401 can be further optimized. Of course, it can be understood that the optimization of this part is implemented in S401. Taking one sub-band of the MS-QP sequence in S401 as an example for description, therefore, for the narrowband ZC sequence on a certain sub-band, based on Formula 1, it can also be equivalent to Formula 13.

[0132]

[0133] where p m satisfies 0 < p m < L m, and gcd(p m , L m ) = 1, is an integer. Of course, for Equation 1, it is the representation when q takes the value of 0. Since the narrowband ZC sequence has many good properties, such as the narrowband ZC sequence being a transverse mode sequence and having a low peak-to-average ratio; and the narrowband ZC sequence having perfect autocorrelation characteristics as shown in Equation 14,

[0134]

[0135] It can be understood that where n”” represents the point to be detected, and m’ represents the point to be detected after time delay. Obviously, when the monitored point of the echo signal after time delay is the same as the point to be detected of the transmitted signal, then L m is output,

[0136] and the corresponding correlation peak can be generated to detect the target. m ) = 1, is a constant

[0137] Due to the perfect autocorrelation characteristics of the narrowband ZC sequence, when it is used as a detection sequence, ideally, a range image with only a single main peak can be obtained to achieve high-precision time delay estimation. Of course, it is assumed that there is only 1 target. When there are multiple targets, a range image with multiple main peaks can be obtained. However, when affected by the Doppler frequency shift, the perfect autocorrelation characteristics will no longer be satisfied. Specifically, when q” = 0, if only the influence of the Doppler frequency shift on the echo signal is considered, Equation 14 can be further expressed as Equation 15.

[0138]

[0139] Among them, taking the remainder of (p m n”’ - v q’ L m )(mod L m ), that is, the remainder of p m n”’ - v q’ L m modulo L m as the independent variable, the image of ||R bb [n””’]|| can be as Figure 17 shown. The influence mechanism of the Doppler frequency shift on the sequence autocorrelation can be seen. When the normalized Doppler parameter v q’ , is very small, v q’ L mCan be approximated to 0, and when the corresponding n”’ takes a non - zero value, the corresponding remainder (i.e., (P m n”’ - v q’ L m )(mod L m )) are all non - zero integers, and the value of ||R bb [n””’]|| is 0. When n”’ takes 0, then ||R bb [n””’]|| approaches the maximum value, generating a correlation peak. Obviously, the narrow - band ZC sequence has perfect autocorrelation characteristics. However, relatively speaking, when the Doppler frequency shift cannot be ignored, then for (p m n”’ - v q’ L m )(mod L m ), the value will deviate from the integer points to a certain extent, making ||R bb [n””’]|| no longer be 0 when n takes non - zero integer values, but fall on the adjacent side lobes. As the Doppler and the sequence increase, when v q’ L m ≥1, the position of the correlation peak will shift, which will seriously affect the ranging accuracy.

[0140] Obviously, if it is assumed that v q’ L m is much less than 1, the smaller ||(p m n”’ - v q’ L m )(mod L m ), that is, the smaller ||(P m n”’)(modL m ), the larger the deviation caused by v q’ L m makes the corresponding ||R bb [n””’]||. And according to number - theory knowledge, it can be known that constitutes a complete residue class modulo L m . Therefore, in some examples, by optimizing P m , it can be made such that the n”’ corresponding to the smaller value of ||(p m n”’)(mod L m ) is concentrated near 0 as much as possible, so that the high side lobes generated by the Doppler frequency shift and the correlation peak can be concentrated as much as possible, thereby avoiding misjudging the range side lobes generated by the Doppler frequency shift as targets.

[0141] In some examples, it can be made such that to meet the above requirements for resisting the Doppler frequency shift. In one example, assuming then (p m 2n”’)(mod Lm ) = L m -2n''', and If we assume L m = 10007, then (p m n''')(mod L m ) can be distributed as shown in Table 1.

[0142] <![CDATA[n”’(mod L m )]]> -4 -3 -2 -1 0 1 2 3 4 <![CDATA[||(p m n”’)(mod L m )||]]> 2 -5002 1 -5003 0 5003 -1 5002 -2

[0143] Table 1

[0144] It can be seen from Table 1 that obviously when ||(p m n''')(mod L m )|| takes a relatively small value, the corresponding n''' is distributed near both sides of the 0 value. At this time, if target detection is performed, the high sidelobes will be concentrated near the correlation peak to reduce the influence of the Doppler frequency shift.

[0145] It can be understood that the parameter n''' involved in the above optimization of the root index can also be replaced by n and n'''.

[0146] Figure 18 Then it shows the schematic diagram of the range profile before the root index optimization. This figure is drawn with L m = 10007 and P m = 3 as an example. Obviously, when the root index is 3, obvious sidelobes appear at positions where the time delay is more than 4000 and nearly 8000. For such obvious sidelobes, it is very easy to be misjudged as a target. But through Figure 19 it can be seen that after the optimized root index is 5003, the high sidelobes generated by the Doppler frequency shift are well gathered near the correlation peak. Therefore Figure 19 only one correlation peak is seen. It can be understood that for Figure 18 and Figure 19 both are illustrated with the number of targets being 1.

[0147] For multiple subbands in the MS-QP sequence, different subband components are orthogonal to each other (it can also be said that the cross-correlation is 0). Therefore, the autocorrelation characteristic of the MS-QP sequence is equivalent to the superposition of the autocorrelations on different subband components. For each subband, the distribution of its autocorrelation sidelobes mainly depends on the autocorrelation distribution of the narrowband ZC sequence on that subband. Therefore, for the Doppler frequency shift received by the MS-QP sequence, the sidelobe distribution generated on the range profile mainly depends on the narrowband ZC sequences on each subband. Therefore, it can be understood that for each subband, the root index can be independently optimized according to the narrowband ZC sequence on that subband. So that the sidelobes generated on the range profile corresponding to the final MS-QP sequence can be well gathered near the correlation peak.

[0148] It can be understood that the optimization of the root index involved above is implemented when the communication cooperation sequence signal is sent in S401. Actually, it is to optimize the root index in the communication cooperation sequence signal so that after the echo signal of the communication cooperation sequence signal is received in S402, target detection can be performed well.

[0149] Continuing back to S402, Figure 20 This is a schematic diagram for constructing the echo signal of a receiving device provided by an embodiment of the present application. Corresponding to Figure 5 and Figure 6 correspondingly, Figure 20 the corresponding receiving device is shown. y(t) represents the analog signal of the echo signal and y[n] represents the baseband digital signal of the echo signal. Obviously, the symbol interval of y[n] and Figure 5 and Figure 6 the x[n] in is obviously the same, both being T M . Through Figure 20 it can be seen that in the receiving device 120, multiple band-pass filters are first required to separate the signals corresponding to different sub-bands. Then, for the signals on each sub-band, they are further subjected to analog-to-digital conversion by a low-sampling ADC to obtain the digital baseband signals corresponding to the sub-bands. After that, sequence reconstruction is performed through the digital signal processing module, and y[n] is obtained. Among them, it can be seen that when separating each sub-band, it can be achieved through reverse spectral shift. For example, Figure 20 in, the signals on each sub-band are separated by multiplying by through a multiplier.

[0150] Continuing back to Figure 4 , after S402, S403 will be executed.

[0151] S403, perform FFT on the echo signal to determine the radar detection component of the echo signal in the frequency domain.

[0152] In one example, when the receiver 304 receives the echo signal y[n], the echo signal y[n] can be subjected to FFT, so that the radar detection component of the echo signal can be determined in the frequency domain. It can be understood that y[n] can have multiple sub-bands. Therefore, S403 can be to convert the analog signal on each sub-band into a baseband digital signal through an ADC. Then, for each sub-band, an FFT of L m M' points can be performed to convert from the time domain to the frequency domain. For example, Figure 21 S2101 shown in. At this time, the narrowband ZC sequence transmitted at the corresponding non-zero frequency points can be taken out, that is, the radar detection component.

[0153] In some examples, since y[n] is the echo signal formed after the target reflection of x[n], y[n] should also have a detection sequence component and a data symbol component. Among them, the detection sequence component in y[n] is called the radar detection component, and it is also the MS-QP sequence involved above. For subsequent channel estimation and target detection, that is Figure 21 S2102 in. Of course, in some other examples, since the cross-correlation between the radar detection component and the data symbol component is very small, when y[n] is converted into a baseband digital signal through ADC, the radar detection component may not be separated, but the MS-QP sequence carrying the data symbol component can be directly used for subsequent target detection.

[0154] In some other examples, for each subband, L m After the FFT of M' points is converted from the time domain to the frequency domain, the data sequence at the corresponding zero-frequency point can also be taken out, that is, the data symbol component in y[n]. Then perform L on the data symbol component in y[n] m The IFFT of M' points is converted from the frequency domain to the time domain, that is Figure 21 S2103 in, so that signal demodulation can be continued subsequently, that is Figure 21 S2104 in. This process realizes the data transmission function.

[0155] S404, perform correlation on the detection sequence component and the radar detection component to determine at least one correlation peak and the delay information corresponding to at least one correlation peak.

[0156] In one example, the detection sequence component at the time of transmission and the received radar detection component can be used for correlation to determine one or more correlation peaks and the delay information of each correlation peak.

[0157] Since the cross-correlation between the radar detection component and the data symbol component in y[n] is very small, y[n] and x[n] can usually be directly used for correlation. Therefore, first, the received echo signal y[n] can be determined, which can be referred to as shown in Formula 11. Of course, in some examples, in order to overcome the problem of weak signal-to-noise ratio of the transmitted signal, when multiple block repetitions are performed through a repeated frame structure in S403 and there is out-of-band leakage, it can be further optimized to Formula 16 based on Formula 12.

[0158]

[0159] Among them, K” represents the number of sub-blocks included in one frame in the repeated frame structure, and K” is a positive integer greater than or equal to 2. k” = 0, 1,..., K” - 1. n1 = 0, 1,..., N1 - 1, and N1 is the length of the MS-QP sequence transmitted on the k”th sub-block. Regarding the noise interference term It can be understood that it may contain noise and data symbols, where the reason for the data symbols in is the existence of Doppler frequency offset and some non-ideal factors, which result in the non-perfect orthogonality between the data symbol components and the detection sequence components during data transmission. Therefore, a small part of interference will still be generated.

[0160] After determining y k” [n1], for each block of y[n], it can be correlated with a single x[n] with a length of L m M’, and it is denoted as r k” [n1]. Assuming a given time n1, the corresponding position value r k” [n1] of the cyclic correlation calculation results of K” blocks is taken, and a qK” - point FFT is performed on the vector composed of k” = 0, 1,..., K” - 1 to obtain the RDM. For example Figure 22 Fig. shows a process of generating DRM. It can be clearly seen that for each element in the DRM, its two - dimensional coordinates respectively correspond to a possible target echo delay and a Doppler frequency shift value. In some examples, for no special processing may be required.

[0161] It can be understood that in some cases, the above x[n] can be replaced by

[0162] After determining the DRM based on the echo signal, it is possible to determine whether there is a correlation peak by the amplitude of each element therein. Of course, in some examples, the target motion speed can also be estimated.

[0163] In one example, a constant false - alarm probability detection method can be used to determine at least one correlation peak. For example, the hypothesis - testing decision threshold is determined by a preset false - alarm rate. And the amplitude of each element at each position in the DRM is compared with this hypothesis - testing decision threshold to determine whether there is a correlation peak. It can be understood that the false - alarm rate can be preset and unchanged, while in each target detection, the hypothesis - testing decision threshold for this time can be dynamically determined according to the false - alarm value. For example, it can be determined by a fully automatic calculation and simulation method to dynamically determine the hypothesis - testing decision threshold according to the false - alarm value. Of course, it can also be implemented by any other equivalent method, and the specific determination process can refer to the existing methods, which will not be elaborated herein. For example, it can be assumed that the DRM determined according to the echo signal is denoted as R(n1, k”), then the hypothesis - testing for determining whether there is a correlation peak in the (n1, k”) cell can be expressed as formula 17.

[0164]

[0165] Among them, H1 represents the discovery of a relevant peak (i.e., the target), and H0 represents the non-discovery of a relevant peak (i.e., the target). T 门限 represents the decision threshold of this hypothesis test, and σ 2 represents the noise power in the corresponding DRM unit.

[0166] In one example, if a relevant peak is detected in the (n1, k") cell, the time delay estimate of the corresponding target can be expressed as τ = n1T s , demonstrating that the estimated τ is the time delay information corresponding to this relevant peak. The corresponding Doppler frequency offset parameter can be expressed as In some examples, the corresponding target speed u can be expressed by Equation 18, including both positive and negative speed cases.

[0167]

[0168] The target motion speed estimated by Equation 18 has an absolute error range of The average absolute error is where λ represents the wavelength of the terahertz signal, for example, it can be 3×10 8 / f c .

[0169] Continuing back to Figure 4 , when it is determined in S404 based on at least one relevant peak and the time delay information corresponding to at least one relevant peak, S405 can be continued.

[0170] S405, based on at least one relevant peak and the time delay information corresponding to at least one relevant peak, determine at least one target and at least one target distance.

[0171] Based on the at least one relevant peak determined in S404 and the time delay information of each relevant peak, at least one target and the corresponding target distance can be determined.

[0172] In one example, considering that the communication cooperative sequence signal adopted above can gather the sidelobes caused by Doppler frequency shift near the relevant peak, and in practice, the probability of multiple targets appearing in a small range is often extremely low. Therefore, it can be assumed that there are no other targets in the vicinity of the relevant peak. Thus, the influence of Doppler sidelobes on the false alarm probability of the system can be reduced. For example, it can be assumed that the th cell in the RDM detects a relevant peak, then it is considered that there are no other targets within the range except the target corresponding to the relevant peak. Among them, n0 can be understood as the preset dynamic range. Therefore, based on each relevant peak, the unique target corresponding to it can be determined.

[0173] In another example, for the determination of the target distance, it can be estimated as where c is the propagation speed of electromagnetic waves (which can also be called the speed of light). In a high signal-to-noise ratio environment, then d 目标距离 The absolute error range of can be And the mean absolute error is

[0174] So far, the detection of the target has been achieved through the above method. In this application, by extending based on the time domain, a communication cooperation sequence signal composed of detection sequence components is determined. By performing time domain extension on the detection sequence, multiple zero-value frequency points are generated in the spectrum of the extended detection sequence components, so as to transmit data symbol components, thereby realizing the simultaneous non-interference of communication and detection functions. Of course, the above method ensures that it can support the correlation detection of long sequences with a low-complexity algorithm. Since the detection sequence component is an MS-QP sequence based on spectrum spreading, the problem of high requirements for the ADC sampling rate in the receiving device by terahertz ultra-wideband signals is solved by dividing it into multiple subbands. At the same time, narrowband ZC sequences are transmitted on each subband, so it has good autocorrelation characteristics. It ensures that while the receiving device utilizes the ultra-high bandwidth, it can use a low-sampling-rate ADC to collect and recover the signal, effectively reducing costs.

[0175] Of course, this application also simultaneously solves the problem that the multi-subband sequence no longer has a constant modulus property and generates a high peak-to-average ratio. Different phase factors are multiplied to the different subband components of the sequence, and the phase factors are optimized to reduce the peak-to-average ratio of the sequence without affecting the autocorrelation characteristics of the sequence. And, to solve the problem of the influence of strong Doppler frequency shift on the terahertz detection performance, the root index in the MS-QP sequence is optimized, so that the high-range image sidelobes caused by Doppler frequency shift gather near the main peak, and a main peak adjacent region exclusion strategy is proposed to effectively reduce the interference of Doppler on target detection.

[0176] Figure 23 It is a single-subband spectrum schematic diagram of a communication cooperation sequence signal provided by an embodiment of this application.

[0177] As Figure 23 shown, it is a single-subband spectrum schematic diagram after substituting specific parameters into the communication cooperation sequence signal involved above. Among them, for the MS-QP sequence in the communication cooperation sequence signal, the length L of the narrowband ZC sequence in a single subband is taken m as 1007, and the root index p m is 503 to minimize the influence of Doppler frequency shift on target detection. Referring to the manner shown in Figure 5 and Figure 6 shown, assuming there are 10 subbands, then M = 10 subbands are mosaicked in the spectrum, and at the same time, L can be set between adjacent subbands GA frequency-domain guard interval of 100. Then the length N = ML can be obtained. G + ∑L m For the MS-QP sequence. The symbol interval of the narrowband ZC sequence within a single sub-band can be set to 1.1 nanoseconds (ns), and the total length of the sequence is 1.1077 microseconds (μs). After passing through the shaping filter, a sub-band component can be formed with a bandwidth of 0.9 GHz. The different sub-band components are shifted and spliced in the frequency spectrum to form adjacent M = 10 sub-bands, and a 0.1 GHz frequency-domain guard interval is set between the sub-bands to form an MS-QP sequence with a total bandwidth of 10 GHz.

[0178] The time-domain expansion factor M' of the MS-QP sequence can be set to 2. That is, in the MS-QP sequence, the narrowband ZC sequence corresponding to the length L m in a single sub-band is repeated 2 times in the time domain to form a sequence with a length of 2L m . According to the above Figure 13 corresponding video correspondence, the sequence with a length of 2L m will only occupy even frequency points after DFT, so data sequences can be modulated on the technical frequency points. For example, take a data sequence S m with a length of L = 1007, i’，m S = |[s i’，m [0], s i’，m [1],..., s i’，m [L m - 1]| (i' = 1, 2,..., M' - 1), and it is also extended to a data sequence with a length of 2L through phase rotation, expressed as m According to the video correspondence of the sequence, the data sequence with a length of 2L only occupies odd frequency points, so it can be compatible with the detection sequence component without interference. As m shown, taking a sub-band as an example, its detection sequence component and data symbol component have no influence on each other after superposition. Whenever the frequency takes an integer, the amplitude of one sequence is 0, and the amplitude of the other sequence is relatively high, and they do not interfere with each other. Correspondingly, the sequence length of the MS-QP sequence is M' times that before expansion. In the figure, the detection sequence component and data symbol component are represented by lines with different thicknesses. Figure 23 As shown, taking a sub-band as an example, its detection sequence component and data symbol component have no influence on each other after superposition. Whenever the frequency takes an integer, the amplitude of one sequence is 0, and the amplitude of the other sequence is relatively high, and they do not interfere with each other. Correspondingly, the sequence length of the MS-QP sequence is M' times that before expansion. In the figure, the detection sequence component and data symbol component are represented by lines with different thicknesses.

[0179] To resist the extremely low signal-to-noise ratio in the terahertz band, multiple repeated transmissions can be performed when the transmitting device sends the communication cooperation sequence signal. When the receiving device receives the echo signal, high-precision ranging and velocity measurement under low signal-to-noise ratio are achieved through the correlation detection of consecutive multiple received sequence word blocks. For example, for a single received word block, the receiving device samples the echo signals of each sub-band through M = 10 band-pass filters with a sampling period of 1.1 ns. Sequences of length 1007 are taken on each sub-band, and then the echo signals of each sub-band are frequency-shifted and spliced in the frequency domain to restore the ultra-wideband received sequence of this word block, that is, the echo signal. The length is N = ML G +∑L m where L G = 100. This echo signal is equivalent to the sequence obtained by directly sampling the live-stripped signal with a sampling period of T s = 0.1 ns. The receiving device collects K” blocks of echo signals of length N for processing, denoted as y k” [n], n = 0, 1,..., N - 1, k” = 0, 1,..., K” - 1.

[0180] In one example, for instance, the echo signals of each sub-block are circularly correlated with the MS-QP sequence with a length of N to form the correlation matrix r k” [n]. The correlation values at the nth position in the circular correlation calculation results of k” blocks are jointly subjected to qk” -point FFT to obtain the RDM for subsequent signal processing. For example Figure 24 the signal waveform schematic diagram of the DRM generation process shown in. Among them, Figure 24 (a) in shows the waveform schematic of the received echo signal. For example, the black vertical lines therein represent the echo signal of a certain block. Obviously, (a) is composed of the superposition of multiple blocks of echo signals. Based on (a), each block of echo signal can be circularly correlated with the transmitted communication cooperation sequence signal, and then (b) is obtained. It can be seen that regardless of which sub-block it is, the position with the highest correlation value is almost the same, that is, the white horizontal line in (b). By performing FFT horizontally on (b), the RDM is obtained, as shown in (c). It can be seen that the correlation peaks in (c) converge into a white dot, that is, the white dot in the middle of (c). Thus, the target distance and the target motion speed can be determined according to the horizontal and vertical coordinates of the RDM respectively.

[0181] In some examples, the performance of the communication cooperation sequence signal involved in the present application can be tested through simulation evaluation. Specifically, reference can be made to the terahertz system parameters shown in Table 2.

[0182] Parameter Value Parameter Value Center frequency 300 GHz Maximum path loss (one-way) -91.5 dB Communication bandwidth 10 GHz Antenna and ambient temperature 285k Transmit power 8.5 dBm (PA) Noise figure of receiving device 11 dB Transmit and receive antenna gain 40 dBi Ranging range Within 3 m Maximum ranging range 3m Velocity measurement range -20 m / s to 20 m / s Reflection attenuation 25 dB

[0183] Table 2

[0184] In one example, when testing with the terahertz system parameters shown in Table 2, it can be determined that the signal-to-noise ratio of the receiving device for terahertz detection within a 3m detection range is generally higher than -56.5 dB. At the same time, during the signal transmission process, it is assumed that the phase noise follows a symbol-by-symbol random walk model. Among them, the symbol-by-symbol random walk model can be, for example, the phase noise θ x1 of a certain symbol period can be expressed as the phase noise θ x1-1 of the previous symbol plus a random increment Δθ x1 , and this increment is a random variable that follows Δθ x1 ~N2(0, (0.316°)). Then the I / Q imbalance parameter of the receiving device can be calculated by Formula 19 and Formula 20.

[0185] μ I / Q = cos(φ) - jεsin(φ) …… Formula 19

[0186] υ I / Q = εcos(φ) - j sin(φ) …… Formula 20 Among them, ε = 0.2 and φ = 10°.

[0187] In some examples, during the simulation, the MS-QP sequence and the communication cooperation sequence signal involved in the present application were compared with the narrowband ZC sequence, the broadband ZC sequence, and the chirp signal. Among them, the length of the narrowband ZC sequence is set to 1007, the root index is set to 503, the symbol interval of the narrowband ZC sequence is set to 1.1 ns, the total sequence length is 1.1077 μs, which is the same length as the MS-QP sequence, and the bandwidth is 0.9 GHz. For the broadband ZC sequence, the length is set to 11077, the root index is 5538, the symbol interval is 0.1 ns, the total sequence length is 1.1077 μs, and the bandwidth is 10 GHz. For the current chirp signal, the pulse length is set to 1.1077 μs and the bandwidth is 10 GHz. The MS-QP sequence and its reference sequence are both transmitted 1024 times. Since the length of the communication cooperation sequence signal is M' times that of the MS-QP sequence, for relatively fair comparison, the communication cooperation sequence signal is repeated 1024 / M' times. For the MS-QP sequence and the communication cooperation sequence signal, their specific parameters can refer to Figure 23 the values set in

[0188] Figure 25It shows the comparison of the ranging performance among the MS-QP sequence, the communication cooperation sequence signal, the narrowband ZC sequence, the wideband ZC sequence, and the chirp signal. Among them, the abscissa is the signal noise ratio (SNR) in dB, and the ordinate is the average absolute ranging error, which is used to reflect the ranging performance of the sequence. It can be seen that for any sequence or signal, as the SNR continuously increases, its average ranging error decreases, and even shows a cliff-like drop within a certain SNR range. Until the ranging error stabilizes after decreasing to a certain extent due to the limitation of the communication bandwidth. For ultra-wideband detection sequences, such as the MS-QP sequence, the wideband ZC sequence, and the chirp signal, the average absolute ranging error reaches a constant value of about 0.0035 m at an SNR of about -55 dB, achieving centimeter-level ranging accuracy. Due to the limited bandwidth of the narrowband ZC sequence, the constant value reached by the average absolute ranging error is higher, about 0.04 m. It can be seen that the MS-QP sequence can achieve almost the same ranging accuracy as the equal-bandwidth ZC sequence, and at the same time, it can use multi-subband parallel filtering for transmission and reception, greatly reducing the requirements for the DAC in the transmitting device and the ADC in the receiving device.

[0189] For the communication cooperation sequence signal (i.e., the communication detection integrated waveform in the figure), it can achieve the same ranging accuracy as the fading energy detection sequence while supporting communication. However, due to the equal distribution of the transmission energy between communication and detection, when achieving high-precision positioning, the minimum SNR usually increases by 3 dB compared with the MS-QP sequence. When the SNR is higher than -52 dB, the superposition of the data symbol component will not affect the ranging accuracy of the detection sequence component.

[0190] Figure 26 It shows the comparison of the velocity measurement performance of the above five sequences. Among them, the velocity measurement performance is usually determined by the length of the detection sequence. Therefore, sequences with the same duration can achieve basically the same velocity measurement performance. Through Figure 26 It can be seen that when the SNR is higher than -55 dB, the average absolute velocity measurement error of different detection sequences can basically reach a constant value. For the communication cooperation sequence signal (i.e., the communication detection integrated waveform in the figure), after adding the data symbol component, usually an additional 3 dB of average absolute velocity measurement error is required to reach the constant value. When the SNR is higher than -52 dB, the superposition of the data symbol component will not affect the velocity measurement accuracy of the detection sequence component.

[0191] In one example, the detection sequence component and the data symbol component in the communication cooperation sequence signal can be transmitted simultaneously without interference. Among them, the time-domain expansion parameter M' determines the proportion of the data symbol component and the detection sequence component in the frequency-domain resources. For example, the detection sequence component occupies 1 / M' of the available frequency-domain resources. Increasing M' can improve the communication data transmission efficiency. However, when M' exceeds a certain threshold, it will affect the ranging and velocity measurement accuracy. Therefore, the value of M' can be dynamically adjusted according to the actual situation to achieve a perfect balance between communication performance and detection performance. For example Figure 27 shows the influence on the average absolute ranging error under different frequency-domain proportions. It can be seen that under the same signal-to-noise ratio, when the frequency-domain proportion of the detection sequence component exceeds a certain value, the average absolute ranging error will tend to a constant value to achieve centimeter-level positioning accuracy. When the frequency-domain proportion of the detection sequence component is less than this value, the average absolute ranging error will gradually deteriorate. Taking -47dB as an example, it can be seen that when the frequency-domain proportion of the detection sequence component is not less than 1 / 10, the average absolute ranging error will tend to a constant value. For -44dB, since its signal-to-noise ratio has reached a relatively good state, the frequency-domain proportion of the detection sequence component will not affect the average absolute ranging error. Another example Figure 28 shows the influence on the average absolute velocity measurement error under different frequency-domain proportions. Similarly, under the same signal-to-noise ratio, when the frequency-domain proportion of the detection sequence component exceeds a certain value, the average absolute velocity measurement error will tend to a constant value. When the frequency-domain proportion of the detection sequence component is less than this value, the average absolute velocity measurement error will gradually deteriorate. Still taking -47dB as an example, it can be seen that when the frequency-domain proportion of the detection sequence component is not less than 1 / 10, the average absolute ranging error will tend to a constant value. For -44dB, since its signal-to-noise ratio has reached a relatively good state, the frequency-domain proportion of the detection sequence component will not affect the average absolute velocity measurement error.

[0192] Figure 29 FIG. is a schematic diagram of another communication detection integrated device provided by an embodiment of the present application.

[0193] As Figure 29 shown, the present application also provides another communication detection integrated device 2900. The device 2900 includes:

[0194] A transmitting module 2901, configured to transmit a communication cooperation sequence signal. Among them, a signal generation module 2903 is configured to determine a communication cooperation sequence signal. The communication cooperation sequence signal includes a detection sequence component, and the detection sequence component is an MS-QP sequence with multiple subbands, and each subband includes a narrowband ZC sequence.

[0195] A receiving module 2902, configured to receive an echo signal of the communication cooperation sequence signal.

[0196] The signal processing module 2904 is configured to perform a fast Fourier transform on the echo signal to determine the radar detection component of the echo signal in the frequency domain.

[0197] The signal processing module 2904 is further configured to correlate the detection sequence component and the radar detection component to determine at least one correlation peak and the time delay information corresponding to at least one correlation peak.

[0198] The signal processing module 2904 is further configured to determine at least one target and the distance of the at least one target according to at least one correlation peak and the time delay information corresponding to at least one correlation peak.

[0199] In a possible implementation manner, the signal generation module 2903 is further configured to: perform phase adjustment on each ZC sequence in the MS-QP sequence by using an optimal phase factor set.

[0200] In a possible implementation manner, the ZC sequence includes: a sequence length L m and a root index p, where the root index p satisfies L m represents the length of the ZC sequence on the m-th subband, and m is a positive integer greater than or equal to 2.

[0201] In a possible implementation manner, the signal generation module 2903 is further configured to: set a frequency domain guard interval between the ZC sequences of every two adjacent subbands.

[0202] In a possible implementation manner, the communication cooperation sequence signal further includes: a data symbol component. Wherein, the data symbol component includes data sequences of multiple subbands. The signal generation module 2903 is further configured to transmit the data sequence on each subband at multiple zero-frequency points on the subband, and the zero-frequency points are obtained by M retransmissions of the ZC sequence on the subband in the time domain.

[0203] In a possible implementation manner, the signal generation module 2903 is further configured to: perform corresponding phase adjustment on the data sequence transmitted on each subband.

[0204] In a possible implementation manner, the signal processing module 2904 is further configured to: at least one correlation peak corresponds to at least one target one by one; and, determine the target distance of the target corresponding to at least one correlation peak according to the time delay information corresponding to at least one correlation peak.

[0205] The apparatus 2900 provided in this application can implement any one of the methods described above Figures 1 to 28 The specific implementation manner can refer to the corresponding description above Figures 1 to 28 and will not be elaborated here.

[0206] Figure 30Schematic diagram of another communication detection integrated device provided by an embodiment of this application.

[0207] As Figure 30 shown, another communication detection integrated device 3000 is shown. The communication detection integrated device 3000 may be the communication detection integrated device in the above Figures 1 to 29 involved solution.

[0208] The communication detection integrated device 3000 may include a processor 3010, an external memory interface 3020, an internal memory 3021, a universal serial bus (USB) interface 3030, a charging management module 3040, a power management module 3041, a battery 3042, an antenna 1, an antenna 2, a mobile communication module 3050, a wireless communication module 3060, and a display screen 3070, etc.

[0209] It can be understood that the structure schematically shown in the embodiments of the present invention does not constitute a specific limitation on the communication detection integrated device 3000. In other embodiments of this application, the communication detection integrated device 3000 may include more or fewer components than shown in the figure, or combine certain components, or split certain components, or have different component arrangements. The components shown in the figure may be implemented in hardware, software, or a combination of software and hardware.

[0210] Among them, the processor 3010, the external memory interface 3020, and the internal memory 3021 may refer to Figure 3 the corresponding descriptions of the processor 301 and the memory 302 in

[0211] Some embodiments, the processor 3010 may include one or more interfaces. The interfaces may include an inter-integrated circuit (I2C) interface, an inter-integrated circuit sound (I2S) interface, a pulse code modulation (PCM) interface, a universal asynchronous receiver / transmitter (UART) interface, a mobile industry processor interface (MIPI), a general-purpose input / output (GPIO) interface, a subscriber identity module (SIM) interface, and / or a universal serial bus (USB) interface, etc.

[0212] The USB interface 3030 is an interface that complies with the USB standard specification. Specifically, it can be a Mini USB interface, a Micro USB interface, a USB Type C interface, etc. The USB interface 3030 can be used to connect a charger to charge the distributed recording device 1700, and can also be used to transfer data between the communication detection integrated device 3000 and peripheral devices. It can also be used to connect headphones to play or collect audio through the headphones. This interface can also be used to connect other electronic devices, such as AR devices, etc.

[0213] It can be understood that the interface connection relationship between the modules illustrated in the embodiments of the present invention is only illustrative and does not constitute a structural limitation on the communication detection integrated device 3000. In other embodiments of the present application, the communication detection integrated device 3000 can also adopt different interface connection methods in the above embodiments, or a combination of multiple interface connection methods.

[0214] The wireless communication function of the communication detection integrated device 3000 can be implemented by antenna 1, antenna 2, mobile communication module 3050, wireless communication module 3060, modulation and demodulation processor, baseband processor, etc.

[0215] Antenna 1 and antenna 2 are used to transmit and receive electromagnetic wave signals. Each antenna in the communication detection integrated device 3000 can be used to cover a single or multiple communication frequency bands. Different antennas can also be multiplexed to improve the utilization rate of the antennas. For example: Antenna 1 can be multiplexed as a diversity antenna for a wireless local area network. In some other embodiments, the antenna can be used in combination with a tuning switch.

[0216] The mobile communication module 3050 can provide solutions for wireless communications including 2G / 3G / 4G / 5G / 6G, etc. applied to the communication detection integrated device 3000. The mobile communication module 3050 can include at least one filter, switch, power amplifier, low noise amplifier (LNA), etc. The mobile communication module 3050 can receive electromagnetic waves by antenna 1, filter, amplify, etc. the received electromagnetic waves, and transmit them to the modulation and demodulation processor for demodulation. The mobile communication module 3050 can also amplify the signal modulated by the modulation and demodulation processor and convert it into electromagnetic waves through antenna 1 for radiation. In some embodiments, at least some functional modules of the mobile communication module 3050 can be disposed in the processor 3010. In some embodiments, at least some functional modules of the mobile communication module 3050 and at least some modules of the processor 3010 can be disposed in the same device.

[0217] The modulation and demodulation processor may include a modulator and a demodulator. Among them, the modulator is used to modulate the low-frequency baseband signal to be transmitted into a medium-high frequency signal. The demodulator is used to demodulate the received electromagnetic wave signal into a low-frequency baseband signal. Subsequently, the demodulator transmits the demodulated low-frequency baseband signal to the baseband processor for processing. After being processed by the baseband processor, the low-frequency baseband signal is transmitted to the application processor.

[0218] The wireless communication module 3060 can provide wireless communication solutions applied to the communication and detection integrated device 3000, including wireless local area networks (WLANs) (such as WiFi networks), Bluetooth, global navigation satellite systems (GNSS), frequency modulation (FM), near field communication (NFC), infrared technology (IR), etc. The wireless communication module 3060 can be one or more devices integrating at least one communication processing module. The wireless communication module 3060 receives electromagnetic waves via the antenna 2, performs frequency modulation and filtering processing on the electromagnetic wave signals, and sends the processed signals to the processor 3010. The wireless communication module 3060 can also receive the signal to be transmitted from the processor 3010, perform frequency modulation and amplification on it, and convert it into electromagnetic waves through the antenna 2 and radiate it out.

[0219] In some embodiments, the antenna 1 of the communication and detection integrated device 3000 is coupled to the mobile communication module 3050, and the antenna 2 is coupled to the wireless communication module 3060, so that the communication and detection integrated device 3000 can communicate with the network and other devices through wireless communication technologies.

[0220] The display screen 3070 is used to display images, videos, etc. The display screen 3070 includes a display panel. The display panel can adopt a liquid crystal display (LCD), an organic light-emitting diode (OLED), an active matrix organic light-emitting diode (AMOLED), a flexible light-emitting diode (FLED), a Miniled, a MicroLed, a Micro-oLed, a quantum dot light-emitting diode (QLED), etc. In some embodiments, the communication and detection integrated device 3000 may include at least one display screen 3070.

[0221] Compared with the existing communication and detection integration, which includes using single-carrier / multi-carrier communication waveforms directly for radar detection, data frame preambles for radar detection, and direct sequence spread spectrum signals for communication detection cooperation, there are many problems such as high peak-to-average ratio, non-ideal autocorrelation characteristics, limited code length, and low data rate. And it cannot solve the technical challenges faced by communication and detection integration in the ultra-wideband terahertz environment, such as high path loss, high hardware cost, and high Doppler frequency shift. The communication cooperation sequence signal involved in this application cleverly divides the terahertz ultra-high bandwidth into multiple adjacent subbands and loads narrowband ZC sequences on different subbands. This enables good autocorrelation characteristics to be obtained, and only by using a band-pass filter and a low-sampling-rate ADC to process different subbands respectively can the acquisition of broadband signals be completed, achieving centimeter-level ranging accuracy and effectively reducing the hardware cost.

[0222] This application designs the waveform of the communication cooperation sequence signal to be sent. By performing multiple-time time-domain expansion on the detection sequence, zero-frequency points appear inside the spectrum of the expanded detection sequence components. Then, the data sequence components are loaded on the zero-frequency points, thus realizing the simultaneous and non-interfering operation of the detection and communication functions. At the same time, for radar detection, this design does not sacrifice the bandwidth of the detection signal, so it will not affect the ranging resolution. It also supports correlation detection of long sequences with a low-complexity algorithm. For communication reception, the detection sequence components in the communication cooperation sequence signal will not interfere with the data sequence components and can be used for channel estimation to assist the reception of communication data.

[0223] Since the detection sequence component in the communication cooperation sequence signal of the present application divides the ultra-wideband into multiple sub-bands, and each sub-band transmits a narrowband ZC subsequence, the spectrum expansion of the narrowband sequence is realized. This makes the detection sequence component have good autocorrelation characteristics, can achieve high ranging resolution by using ultra-high bandwidth, and only requires a band-pass filter and a low-sampling-rate ADC for reception and reconstruction.

[0224] Furthermore, in order to reduce the peak-to-average power ratio of the transmitted signal, the present application can also multiply the signals of different sub-bands by different phase factors in the frequency domain. After optimization, the peak-to-average power ratio of the sequence can be effectively reduced, and at the same time, the detection performance of the sequence is basically not affected.

[0225] Furthermore, for the Doppler frequency shift problem generally ignored in the traditional method, in order to avoid the high-range-profile sidelobes caused by Doppler frequency shift, the present application optimizes the root index of the narrowband ZC sequences on each sub-band in the detection sequence component. After the root index is optimized, the high-range-profile sidelobes caused by Doppler frequency shift can be gathered near the main peak. At the same time, by using the exclusion strategy in the adjacent area of the main peak, assuming that there are no other targets in the area adjacent to the target corresponding to the main peak, the probability of misjudging the high-range-profile sidelobes as targets is reduced, and the influence of Doppler frequency shift on target detection is effectively reduced.

[0226] Those of ordinary skill in the art should further realize that, combining the units and algorithm steps of the examples described in conjunction with the embodiments disclosed herein, can be implemented by electronic hardware, computer software, or a combination of the two. To clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described according to functions in the above description. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present application.

[0227] Those of ordinary skill in the art can understand that all or part of the steps in implementing the methods of the above embodiments can be completed by instructing a processor through a program. The program can be stored in a computer-readable storage medium, and the storage medium is a non-transitory medium, such as random access memory, read-only memory, flash memory, hard disk, solid-state drive, magnetic tape, floppy disk, optical disc, and any combination thereof.

[0228] As described above, it is only the preferred specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A target detection method, characterized in that, The method includes: Sending a communication cooperation sequence signal, where the communication cooperation sequence signal includes a detection sequence component and a data symbol component. The detection sequence component is a multi-subband quasi-perfect MS-QP sequence with multiple subbands. Each subband includes a narrowband Zadoff-Chu (ZC) sequence. The data symbol component includes data sequences of multiple subbands. The data sequences on each subband are transmitted at multiple null frequency points on the subband, and the null frequency points are obtained by performing M retransmissions of the ZC sequence on the subband in the time domain; Receiving an echo signal of the communication cooperation sequence signal; Performing a fast Fourier transform on the echo signal to determine a radar detection component of the echo signal in the frequency domain; Correlating the detection sequence component and the radar detection component to determine at least one correlation peak and delay information corresponding to the at least one correlation peak; Determining at least one target and the distance of the at least one target according to the at least one correlation peak and the delay information corresponding to the at least one correlation peak.

2. The method according to claim 1, characterized in that The method further includes: Performing phase adjustment on each ZC sequence in the MS-QP sequence by using an optimal phase factor set.

3. The method according to claim 1 or 2, characterized in that, The ZC sequence includes: a sequence length L m and a root index p, where the root index p satisfies L m represents the length of the ZC sequence on the m-th subband, and m is a positive integer greater than or equal to 2.

4. The method according to claim 1, wherein The method further includes: There is a frequency domain guard interval between the ZC sequences of every two adjacent subbands.

5. The method according to claim 1, characterized in that, The method further includes: Performing corresponding phase adjustment on the data sequences transmitted on each subband.

6. The method according to claim 1, wherein The determining at least one target and the distance of the at least one target according to the at least one correlation peak and the delay information corresponding to the at least one correlation peak includes: The at least one correlation peak corresponds to the at least one target one by one; and, determining the target distance of the target corresponding to the at least one correlation peak according to the delay information corresponding to the at least one correlation peak.

7. A target detection device, characterized in that, The device includes: A transmitter for sending a communication cooperation sequence signal, where the communication cooperation sequence signal includes a detection sequence component and a data symbol component. The detection sequence component is a multi-subband quasi-perfect MS-QP sequence with multiple subbands. Each subband includes a narrowband Zadoff-Chu (ZC) sequence. The data symbol component includes data sequences of multiple subbands. The data sequences on each subband are transmitted at multiple null frequency points on the subband, and the null frequency points are obtained by performing M retransmissions of the ZC sequence on the subband in the time domain; A receiver for receiving an echo signal of the communication cooperation sequence signal; A processor for being coupled to a memory and reading and executing instructions stored in the memory; When the processor runs, it executes the instructions, so that the processor is used to perform a fast Fourier transform on the echo signal to determine a radar detection component of the echo signal in the frequency domain; correlate the detection sequence component and the radar detection component to determine at least one correlation peak and delay information corresponding to the at least one correlation peak; determine at least one target and the distance of the at least one target according to the at least one correlation peak and the delay information corresponding to the at least one correlation peak.

8. The device according to claim 7, characterized in that The processor is further used for: The optimal phase factor set is used to perform phase adjustment on each of the ZC sequences in the MS-QP sequence.

9. The device according to claim 7 or 8, characterized in that, The ZC sequence includes: a sequence length L m and a root index p, where the root index p satisfies L m represents the length of the ZC sequence on the m-th sub-band, and m is a positive integer greater than or equal to 2.

10. The device according to claim 8, characterized in that, The processor is further configured to: there is a frequency domain guard interval between the ZC sequences of every two adjacent subbands.

11. The device according to claim 7, characterized in that, The processor is further configured to: perform corresponding phase adjustment on the data sequence transmitted on each subband.

12. The device according to claim 7, characterized in that, The processor is further configured to: The at least one correlation peak corresponds one-to-one to the at least one target; and, the target distance of the target corresponding to the at least one correlation peak is determined according to the delay information corresponding to the at least one correlation peak.

13. A computer-readable storage medium storing instructions therein, characterized in that, When the instruction runs on the terminal, the terminal is caused to execute the method according to any one of claims 1-6.

14. A computer device including instructions, which when running on a terminal, causes the terminal to execute the method according to any one of claims 1-6.

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