Millimeter-wave communication and sensing integrated transmission system based on LFM-OFDM signals

Abstract

This invention belongs to the field of communication technology, specifically a millimeter-wave communication and sensing integrated transmission system based on LFM-OFDM signals. The system comprises a transmitter and a receiver. The transmitter mainly includes an input module, an optical modulator, a light source, and a photodetector. The input module generates the information to be modulated; the optical modulator modulates the information to be transmitted onto the sidebands of the optical carrier; an external cavity laser serves as the light source; and the photodetector performs photoelectric conversion. The receiver mainly includes an antenna, a demodulator, and an output module. The antenna receives the millimeter-wave signal and outputs it to the demodulator for demodulation at both the communication and sensing ends; the output module outputs the demodulated information. This system not only enables millimeter-wave band communication and sensing devices but also generates broadband LFM signals, achieving high-resolution sensing and high-speed communication.

Description

Technical Field

[0001] This invention belongs to the field of communication technology, specifically relating to a millimeter-wave communication and sensing integrated transmission system based on LFM-OFDM signals. Background Technology

[0002] From 1G to 5G, communication and sensing functions existed independently, with terminals transmitting information and radar systems handling sensing. With the rapid development of information technology, services have expanded from humans to intelligent agents and physical and virtual spaces, giving rise to emerging application scenarios such as smart transportation, smart healthcare, and autonomous driving. These emerging services place higher demands on the end-to-end signal processing technology of future 6G, making integrated communication and sensing technology a popular candidate. The 6G network will be a fusion of communication, sensing, and computing. On the other hand, 6G communication frequency bands will be further increased, moving towards higher frequency bands such as millimeter waves and terahertz. This means that sensing frequency bands will overlap with communication frequency bands, making research on how to achieve integrated communication and sensing of great significance.

[0003] In a narrow sense, a sensing network refers to a system with capabilities such as ranging, velocity measurement, target imaging, and target recognition. Communication-sensing integration is a novel information processing technology based on the sharing of hardware and software resources, simultaneously achieving synergy between communication and sensing functions. Its goal is to enable wireless communication and wireless sensing—two independent functions—to coexist and cooperate within the same system, improving service quality and efficiency. Communication-sensing integration technology has attracted widespread research interest from the academic community. Huawei Technologies Co., Ltd. has conducted research on the technological challenges and development trends of communication-sensing integration. The IEEE established the ISAC (Integrated Communication-Sensing Emerging Technologies Initiative Committee), inviting renowned scholars and experts in the industry to discuss the latest research results in areas such as standardization and signal processing algorithms for communication-sensing integration technology.

[0004] To achieve high-speed communication and high-resolution sensing, increasing the frequency of carrier and radar signals is an unavoidable technical approach. However, due to the bandwidth limitations of existing electronic devices, generating high-frequency signals in the electrical domain requires multiple frequency multiplications of the original signal, necessitating the use of frequency multipliers and phase-locked loops, which significantly increases system costs. Against this backdrop, this paper utilizes photonic beat frequency technology to convert LFM-OFDM signals to the terahertz band through a single electro-optical-electro-electric conversion, achieving both high-speed communication and high-precision sensing with a single device. Summary of the Invention

[0005] The purpose of this invention is to provide an integrated millimeter-wave communication and sensing transmission system based on LFM-OFDM signals, which achieves high-speed communication and high-resolution ranging while sharing hardware resources between sensing and communication equipment. Compared with the traditional separate communication and sensing functional equipment, it is expected to greatly reduce costs.

[0006] The millimeter-wave communication and sensing integrated system based on LFM-OFDM signals provided by this invention includes:

[0007] (1) The sending end includes:

[0008] Two external cavity lasers (ECLs), wherein the first external cavity laser (ECL1) outputs an optical carrier f. c1 The optical carrier is split into two paths, serving as the optical carrier for the transmitter and receiver optical modulators respectively. The optical carrier f output from the second external cavity laser (ECL2) is... c2 Used to couple with the upper sideband optical signal filtered out by the optical filter, thereby assisting the photodetector (PD1) in generating LFM-OFDM signals in the millimeter-wave band by beat frequency;

[0009] An optical splitter (OC1) splits the optical carrier output from the external cavity laser ECL1 into two paths, upper and lower;

[0010] An arbitrary waveform generator (AWG) is used to generate an LFM-OFDM signal, thereby driving the first optical modulator (MZM1);

[0011] A first optical modulator (MZM1) is used to perform electro-optical conversion and suppress carrier modulation;

[0012] An optical comb filter (Interleaver) filters out the upper sideband signal and the lower sideband signal output by the first optical modulator (MZM1). The upper sideband signal is used for communication and sensing after further processing, while the lower sideband signal is used as the reference optical signal for demodulation at the sensing end.

[0013] An erbium-doped fiber amplifier (EDFA) is used to amplify the optical signal output from an interleaver.

[0014] A first optical coupler (OC2) is used to couple the optical signal output from the erbium-doped fiber amplifier (EDFA) with the optical carrier output from the second external cavity laser (ECL2);

[0015] A power regulator (ATT) is used to regulate the power of the optical signal entering the first photodetector (PD1);

[0016] A first photodetector (PD1) is used to beat the frequency to complete the photoelectric conversion and generate a millimeter-wave band LFM-OFDM signal;

[0017] A low-noise amplifier (LNA) is used to amplify the electrical signal output by the first photodetector (PD1).

[0018] A transmit antenna (HA1) transmits millimeter-wave LFM-OFDM signals from a low-noise amplifier (LNA).

[0019] (2) The receiving end includes:

[0020] Two receiving antennas: the first receiving antenna (HA2) is used to receive millimeter-wave communication signals, and the second receiving antenna (HA3) is used to receive millimeter-wave sensing signals.

[0021] A power amplifier (PA) is used to amplify the signal received by the sensing end;

[0022] Two mixers, namely the first mixer (Mixer1) and the second mixer (Mixer2), are used for down-conversion processing of communication signals and sensing signals, respectively.

[0023] Two local oscillators (LO), namely the first local oscillator (LO1) and the second local oscillator (LO2), are used as the input local oscillator signals of the mixers at the communication end and the sensing end, respectively.

[0024] An electrical amplifier (EA) is used to amplify the down-converted electrical signal at the sensing end;

[0025] A second optical modulator (MZM2) is used for dechirping at the sensing end, and its input optical carrier is the optical carrier f output from the first external cavity laser (ECL1). c1 The radio frequency drive signal is an amplified down-conversion sensing signal;

[0026] A second optical coupler (OC3) is used to couple the modulated signal output from the second optical modulator (MZM2) at the receiver with the lower sideband optical modulated signal filtered out by the optical filter (Interleaver);

[0027] A second photodetector (PD2) performs photoelectric conversion by beat frequency, and its input is the coupling signal output from the second optical coupler (OC3);

[0028] An oscilloscope is used to observe the time-domain waveform and spectrum of a signal from a photodetector (PD2).

[0029] In this invention, the communication signal is an OFDM signal with 2048 subcarriers. Each subcarrier uses QPSK mapping. After down-conversion by a mixer (Mixer1) at the receiving end, the communication signal with superimposed channel noise is acquired by an oscilloscope and then equalized and demodulated using a digital signal processing algorithm on offline programming software.

[0030] In this invention, the sensing signal is a linear frequency modulated (LFM) signal. The frequency of the LFM signal increases linearly with time. The LFM signal ranging principle is essentially to obtain the transmission delay by measuring the frequency increment generated from transmission to reception. Since the speed of electromagnetic wave transmission is known, the target distance can be obtained through the transmission delay. The ranging principle of this system will now be explained in detail.

[0031] Let the initial LFM signal frequency expression be:

[0032] f LFM_initial =f0+kt, (1)

[0033] Where f0 is the initial frequency, the frequency modulation slope k = B / T, B is the LFM signal bandwidth, and T is the time width; then the frequency expressions for the upper sideband signal and lower sideband signal output by the first optical modulator (MZM1) at the transmitting end are:

[0034] f upper_sideband =f c1 +f0+kt, (2)

[0035] f lower_sideband =f c1 -f0-kt, (3)

[0036] The upper sideband signal shown in Equation (2) is coupled at the first optical coupler (OC2) to the optical carrier f from the second external cavity laser (ECL2). c2 After coupling and beat frequency analysis by the first photodetector (PD1), the frequency expression of the millimeter-wave LFM signal is as follows:

[0037] f LFM_transmitted =f c1 +f0+kt-f c2 (4)

[0038] The aforementioned millimeter-wave LFM signal is transmitted into free space via the transmitting antenna (HA1) to detect the target; the frequency expression of the LFM echo signal received by the receiving antenna is:

[0039] f LFM_echo =f c1 +f0+kt-f c2 +kτ, (5)

[0040] Where τ is the transmission delay; after passing through the second mixer (Mixer2), the frequency expression of the intermediate frequency LFM signal is obtained as follows:

[0041] f LFM_IF =f c1 +f0+kt-f c2 +kτ-f LO (6)

[0042] Among them, f LO The frequency of the local oscillator signal is given; Equation (6) contains a chirp term kt. To visually observe the frequency of the LFM echo signal, the chirp term is then eliminated; The input optical carrier of MZM2 comes from the first external cavity laser (ECL1) f c1 Operating at the minimum transmission point, the expression for the negative first-order optical sideband frequency of the output optical signal is:

[0043] f MZM2_output =f c2 -f0-kt-kτ+f LO (7)

[0044] The optical signal shown in equation (7) is coupled at the second optical coupler (OC3) to the lower sideband reference optical signal output from the optical filter (Interleaver) shown in equation (3), and input to the second optical detector (PD2) for beat frequency. A frequency peak can be observed on the oscilloscope (OSC), and the peak frequency is f. c1 -f c2 +kτ-f LO It can be seen that the chirp term kt has been successfully eliminated. To measure the distance between the two targets, the above steps are repeated for each target. Since the distances of the two targets from the radar transmitter are different, the transmission delay τ is different, which is reflected in the difference in the frequency peak observed by the oscilloscope (OSC). Let this frequency peak be Δf, then the distance L between the two targets is obtained as:

[0045]

[0046] At this point, the system has completed its sensing, ranging, and communication functions.

[0047] In this invention, time-division multiplexed sensing-communication signals are used, which is equivalent to inserting block pilot signals.

[0048] In this invention, the communication signal is a multi-carrier OFDM signal, with each subcarrier modulated using 16QAM. The sensing signal is a linear frequency modulated (LFM) signal.

[0049] In this invention, photonic beat frequency technology is used to generate broadband LFM signals and communication signals through a single electro-optical-electro-electric conversion, thereby achieving high-speed communication and high-resolution sensing.

[0050] In this invention, the optical heterodyne method is used to generate a high-frequency millimeter-wave signal by beating the upper sideband signal output by the coupled optical filter (Interleaver) with the optical carrier output by the external cavity laser (ECL2) and assisting the photodetector (PD1).

[0051] In this invention, communication and sensing functions are shared by the same device, thus avoiding the waste of hardware resources.

[0052] This invention proposes an integrated communication and sensing transmission system based on LFM-OFDM signals, the workflow of which (i.e., the connection relationships between the components) is as follows:

[0053] At the transmitting end, the optical carrier output from the first external cavity laser (ECL1) is split into upper and lower paths by the optical splitter (OC1). The first optical modulator (MZM1) receives the LFM-OFDM signal input from the arbitrary waveform generator (AWG) and modulates the upper optical carrier output from the first external cavity laser (ECL1). The lower optical carrier output from the optical splitter (OC1) serves as the input optical carrier for the second optical modulator (MZM2) at the receiving end.

[0054] Suppressed carrier modulation is performed by the first optical modulator (MZM1);

[0055] The upper sideband signal and the lower sideband signal of the output signal of the first optical modulator (MZM1) are filtered out by the optical filter (Interleaver). The upper sideband signal is further processed for communication and sensing, and the lower sideband signal is used as the reference optical signal for the ranging receiver.

[0056] At the second optical coupler (OC2), the upper sideband optical signal output from the optical filter (Interleaver) is coupled with the optical carrier generated by the second external cavity laser (ECL2), and the power of the optical signal entering the first photodetector (PD1) is adjusted by the power regulator (ATT).

[0057] The first photodetector (PD1) beats the frequency to complete the photoelectric conversion and obtain the millimeter-wave band LFM-OFDM signal. At this point, the generation of the communication sensing signal has been completed, and the low-frequency LFM-OFDM signal output by the arbitrary waveform generator (AWG) has been successfully converted to the millimeter-wave band.

[0058] The millimeter-wave LFM-OFDM signal is amplified by a low-noise amplifier (LNA);

[0059] The amplified signal is transmitted through the transmitting antenna to the wireless channel.

[0060] At the communication receiving end, after 1 meter of wireless transmission, the communication receiving antenna (HA2) coherently demodulates the communication signal;

[0061] At the sensing receiver, the reflected LFM echo signal is received through the sensing receiving antenna (HA3);

[0062] The LFM echo signal is amplified by a power amplifier (PA) and mixed with the local oscillator signal (LO) to obtain the intermediate frequency LFM signal;

[0063] The intermediate frequency (LFM) signal output from the second mixer (Mixer2) is amplified by the electrical amplifier (EA) and driven by the second optical modulator (MZM2). The bias voltage of the second optical modulator (MZM2) is adjusted to make it carrier suppression modulation and intensity modulation is applied to the downstream optical carrier output from the optical splitter (OC1).

[0064] The output signal of the second optical modulator (MZM2) at the receiving end is coupled with the ranging reference optical signal output by the optical filter (Interleaver) by the second optical coupler (OC3). The second photodetector (PD2) receives the coupled signal output by the second optical coupler (OC3), and obtains a frequency peak by beat frequency. LFM signals are transmitted to the two targets respectively. Since the distances of the two targets from the radar transmitter are different, the transmission delay of the LFM signal is different. Finally, the frequency peaks displayed on the oscilloscope (OSC) are different. The two frequency peaks are denoted as Δf. The distance between the two targets can be solved according to equation (8).

[0065] Compared to existing technologies, the embodiments of this invention utilize optical heterodyne beat frequency to generate millimeter-wave band LFM-OFDM signals, achieving integrated communication and sensing within a single device. This avoids wasting hardware resources while generating millimeter-wave LFM-OFDM signals through a single electro-optical-electro-electrical conversion, simultaneously realizing high-speed communication and high-resolution sensing. It also addresses the trend of future 6G communication signal frequency bands gradually overlapping with radar signal spectrum bands, providing a new technical solution for future integrated communication and sensing. Attached Figure Description

[0066] Figure 1 This invention presents a millimeter-wave communication sensing integrated transmission system architecture based on LFM-OFDM signals.

[0067] Figure 2 This is the bit error rate curve from a 1-meter wireless transmission experiment.

[0068] Figure 3 This is the result of a 40cm distance measurement experiment.

[0069] The following are the labeling elements in the diagram: 1 is the first external cavity laser (ECL1), 2 is the optical splitter (OC1), 3 is the first optical modulator (MZM1), 4 is the arbitrary waveform generator (AWG), 5 is the optical filter (Interleaver), 6 is the erbium-doped fiber amplifier (EDFA), 7 is the first optical coupler (OC2), 8 is the second external cavity laser (ECL2), 9 is the power conditioner (ATT), 10 is the first photodetector (PD1), 11 is the low-noise amplifier (LNA), 12 is the transmitting antenna (HA1), and 13 is the communication receiving antenna (H). A2), 14 is the first mixer (Mixer1), 15 is the first local oscillator (LO1), 16 is the oscilloscope (OSC), 17 is the ranging target (Target), 18 is the sensing end receiving antenna (HA3), 19 is the power amplifier (PA), 20 is the second mixer (Mixer2), 21 is the second local oscillator (LO2), 22 is the electrical amplifier (EA), 23 is the second optical modulator (MZM2), 24 is the second optical coupler (OC3), 25 is the second photodetector (PD2), and 26 is the oscilloscope (OSC). Detailed Implementation

[0070] The present invention will now be described in detail with reference to the accompanying drawings.

[0071] Figure 1 The diagram shows the architecture of a millimeter-wave communication sensing integrated transmission system based on LFM-OFDM signals, which includes:

[0072] At the transmitting end, an optical splitter (2) is used to split the optical carrier f output by the first external cavity laser ECL1 (1). c1 The optical carrier is divided into two paths: the upper optical carrier serves as the input optical carrier of the transmitting optical modulator (MZM1), and the lower optical carrier serves as the input optical carrier of the receiving optical modulator (MZM2). The generation of the LFM-OFDM signal is implemented by programming on offline programming software. The LFM signal and OFDM signal occupy different time slots, and the generated LFM-OFDM signal is input into the arbitrary waveform generator AWG(4) to complete signal generation. The optical modulator MZM1(3) receives the drive from the LFM-OFDM signal from the arbitrary waveform generator and drives the optical carrier f output by the first external cavity laser ECL1. c1 Suppressed carrier modulation is performed. The upper and lower sideband signals output from the optical modulator MZM1(3) are filtered out using an optical filter Interleaver(5), where the upper sideband signal is used to generate the millimeter-wave LFM-OFDM signal, and the lower sideband signal is used as the reference optical signal for the ranging receiver. The upper sideband signal output from Interleaver(5) is amplified by an erbium-doped fiber amplifier EDFA(6) and coupled to an optical carrier f from the second external cavity laser ECL2(8) at an optical coupler OC2(7).c2 The coupling, power regulator ATT (9) is used to regulate the power of the optical signal entering the photodetector PD1 (10). After the PD1 beats, the millimeter-wave LFM-OFDM signal has been successfully generated. The millimeter-wave signal from PD1 is amplified by the low-noise amplifier LNA (11) and transmitted through the transmitting antenna HA1 (12) for communication and sensing.

[0073] At the receiving end, the millimeter-wave signal is received by the receiving antenna HA2 (13) after a one-meter wireless transmission. The local oscillator signal from the local oscillator LO1 (15) is received by the mixer (14), the millimeter-wave signal is down-converted, and the intermediate frequency signal after down-conversion is captured by an oscilloscope. The channel impairment is compensated by digital signal processing algorithms on offline programming software, and finally the communication signal is demodulated. At this point, the system has completed the communication function.

[0074] At the sensing receiver, the LFM echo signal reflected from the target (17) is received by the receiving antenna HA3 (18), and the power of the LFM echo signal is amplified by the power amplifier PA (19). The millimeter-wave signal is down-converted at the mixer 2 (20), and then the electrical amplifier EA (22) is used to amplify the down-converted intermediate frequency LFM signal. The amplified intermediate frequency signal is used to drive the optical modulator MZM2 (23). The input optical carrier of MZM2 is the down-path optical carrier f output by OC1. c1 To eliminate the chirp term of the LFM signal, the optical signal output from MZM2 (23) is then coupled with the lower sideband ranging reference signal output from Interleaver at the optical coupler OC3 (24). The photoelectric conversion is completed by the beat frequency of the photodetector PD2 (25), and the oscilloscope OSC (26) is used to observe the signal waveform and spectrum. To measure the distance between two targets, the above steps are repeated for each target. Since the distances of the two targets from the radar transmitter are different, the transmission delays are different, which is reflected in the difference in the frequency peak observed by the OSC. This frequency peak is denoted as Δf, and the distance between the two targets can be calculated using formula (8). At this point, the system has completed the ranging function.

[0075] In specific experiments, based on communication functions, 6G Baud and 8G Baud OFDM transmissions were performed. Each OFDM symbol used 16QAM modulation mapping, and the bit error rate was below the FEC threshold, with the highest rate reaching 32Gbit / s. The bit error rate curves are attached. Figure 2 .

[0076] Based on the ranging function, two targets 40cm apart were detected, and the spectrum obtained on the oscilloscope (OSC) is as follows. Figure 3As shown, the frequency difference is 1.2 GHz, while the bandwidth B of the LFM signal is 5 GHz and the time width T is 10. -9 According to equation (8), the distance is 39cm, with an error of 1cm.

[0077] Those skilled in the art will understand that the above embodiments are specific examples of implementing the present invention, and in practical applications, various changes in form and detail may be made without departing from the spirit and scope of the present invention.

Claims

1. A system for millimeter wave communication and sensing integration based on LFM-OFDM signals, characterized in that, The system comprises a transmitting end and a receiving end, wherein the transmitting end comprises: an optical coupler (OC1) for splitting the optical carrier output by a first external cavity laser (ECL1) into two paths; an arbitrary waveform generator (AWG) for generating an LFM-OFDM signal, so as to drive a first optical modulator (MZM1); Two external cavity lasers (ECLs), wherein the first external cavity laser (ECL1) outputs an optical carrier f. c1 The optical carrier is split into two paths, serving as the optical carrier for the transmitter and receiver optical modulators respectively. The optical carrier f output from the second external cavity laser (ECL2) is... c2 Used to couple with the upper sideband optical signal filtered out by the optical filter, thereby assisting the photodetector (PD1) in generating LFM-OFDM signals in the millimeter-wave band by beat frequency; the first optical modulator (MZM1) for completing electro-optical conversion and performing carrier-suppressed modulation; an optical interleaver for filtering out the upper sideband signal and the lower sideband signal output by the first optical modulator (MZM1), wherein the upper sideband signal is used for communication and sensing after subsequent processing, and the lower sideband signal is used as a reference optical signal for demodulation at the sensing end; an erbium-doped fiber amplifier (EDFA) for amplifying the optical signal output by the optical interleaver; a first optical coupler (OC2) for coupling the optical signal output by the erbium-doped fiber amplifier (EDFA) with the optical carrier output by a second external cavity laser (ECL2); a power adjuster (ATT) for adjusting the power of the optical signal entering a first photodetector (PD1); the first photodetector (PD1) for completing photoelectric conversion through frequency mixing to generate an LFM-OFDM signal in the millimeter wave band; a low-noise amplifier (LNA) for amplifying the electrical signal output by the first photodetector (PD1); a transmitting antenna (HA1) for transmitting the millimeter wave LFM-OFDM signal from the low-noise amplifier (LNA); the receiving end comprises: two receiving antennas, a first receiving antenna (HA2) for receiving a millimeter wave communication signal, and a second receiving antenna (HA3) for receiving a millimeter wave sensing signal; a power amplifier (PA) for amplifying the received signal at the sensing end; two mixers (Mixer), i.e., a first mixer (Mixer1) and a second mixer (Mixer2), for down-conversion processing of the communication signal and the sensing signal, respectively; two local oscillators (LO), i.e., a first local oscillator (LO1) and a second local oscillator (LO2), for providing input local oscillator signals for the mixers at the communication end and the sensing end, respectively; an electrical amplifier (EA) for amplifying the electrical signal after down-conversion at the sensing end; a second optical coupler (OC3) for coupling the modulated signal output by a receiving end optical modulator (MZM2) with the lower sideband optical modulated signal filtered out by the optical filter (Interleaver); a second photodetector (PD2) for completing photoelectric conversion through frequency mixing, with the input being the coupled signal output by the second optical coupler (OC3); a second optical modulator (MZM2) for sensing the de-chirp, the input optical carrier of which is the optical carrier f c1 , the radio frequency drive signal being the amplified down-converted sensing signal; an oscilloscope (OSC) for observing the time-domain waveform and the spectrum diagram of the signal from the second photodetector (PD2); and the working process of the system is as follows: ​ ​ At the sending end, the optical carrier output by the first external cavity laser (ECL1) is divided into two paths by the first optical coupler (OC1), the LFM-OFDM signal from the arbitrary waveform generator (AWG) is input to the first optical modulator (MZM1), the upper path optical carrier output by the first external cavity laser (ECL1) is modulated, and the lower path optical carrier output by the optical coupler (OC1) is used as the input optical carrier of the second optical modulator (MZM2) at the receiving end; The first optical modulator (MZM1) performs carrier suppression modulation; The upper sideband signal and the lower sideband signal of the output signal of the first optical modulator (MZM1) are filtered out by the optical filter (Interleaver), the upper sideband signal is used for communication and sensing after subsequent processing, and the lower sideband signal is used as the reference optical signal for ranging at the receiving end; The optical signal output by the optical filter is amplified by the erbium-doped fiber amplifier (EDFA); At the first optical coupler (OC2), the upper sideband optical signal amplified by the erbium-doped fiber amplifier (EDFA) is coupled with the optical carrier generated by the second external cavity laser (ECL2), and the optical signal power entering the first photodetector (PD1) is adjusted by the power adjuster (ATT); The first photodetector (PD1) performs frequency mixing to complete photoelectric conversion to obtain a LFM-OFDM signal in the millimeter wave band, thus completing the generation of the communication and sensing signal, and the low-frequency LFM-OFDM signal output by the arbitrary waveform generator (AWG) is successfully converted to the millimeter wave band; The millimeter wave LFM-OFDM signal is amplified by the low noise amplifier (LNA); The amplified signal is transmitted by the transmitting antenna and transmitted to the wireless channel; At the communication receiving end, the communication signal is coherently demodulated by the first receiving antenna (HA2) after 1 meter wireless transmission; At the sensing receiving end, the LFM echo signal reflected back is received by the second receiving antenna (HA3); The LFM echo signal is amplified by the power amplifier (PA) and mixed with the local signal (LO) to obtain an intermediate frequency LFM signal; The intermediate frequency LFM signal output by the second mixer (Mixer2) is amplified by the electrical amplifier (EA) and drives the second optical modulator (MZM2), adjusts the bias voltage of the second optical modulator (MZM2) to be in carrier suppression modulation, and modulates the lower path optical carrier output by the optical coupler (OC1) in intensity; The output signal of the second optical modulator (MZM2) at the receiving end is coupled with the ranging reference optical signal output by the optical filter (Interleaver) by the second optical coupler (OC3), the coupled signal output by the second optical coupler (OC3) is received by the second photodetector (PD2), and frequency mixing is performed to obtain a frequency peak, two LFM signals are transmitted for two targets respectively, and due to the different distances of the two targets from the radar transmitter, the transmission time delays of the LFM signals are different, which finally manifests as different frequency peaks displayed on the oscilloscope (OSC), and the distance between the two targets is solved by recording the two frequency peaks as Δf. The principle of the ranging end is to convert the transmission delay by measuring the frequency increment generated from the transmission to the reception of the LFM signal, so as to calculate the target distance; the specific flow is as follows: The initial LFM signal frequency expression is as follows: f LFM_initial = f0+ kt, (1) Wherein, f0 is the initial frequency, the frequency modulation slope k=B / T, B is the LFM signal bandwidth, and T is the time width; the upper sideband signal and the lower sideband signal frequency expression output by the first optical modulator (MZM1) of the sending end are as follows: f upper_sideband = f c1 + f0+ kt, (2) f lower_sideband = f c1 - f0- kt, (3) The upper sideband signal shown in formula (2) is coupled at a first optical coupler (OC2) with an optical carrier f c2 Coupling, through the first photodetector (PD1) beat frequency, the obtained millimeter wave LFM signal frequency expression is: f LFM_transmitted = f c1 +f0+kt-f c2 , (4) The above millimeter wave LFM signal is transmitted to the free space through the transmitting antenna (HA1) to detect the target; the LFM echo signal frequency expression received by the receiving antenna is as follows: f LFM_echo = f c1 +f0+kt-f c2 +kτ, (5) Wherein, τ is the transmission delay; after the second mixer (Mixer2), the intermediate frequency LFM signal frequency expression is as follows: f LFM_IF = f c1 +f0+kt-f c2 +kτ-f LO , (6) where f LO is the frequency of the local oscillator signal; the chirp term kt in equation (6) is eliminated for the sake of visualizing the frequency of the LFM echo signal; the input optical carrier of MZM2 comes from the first external cavity laser (ECL1) with f c1 , working at the minimum transmission point, the expression of the negative first-order optical sideband frequency of the output optical signal is: f MZM2_output = f c2 -f0-kt-kτ+f LO , (7) The optical signal shown in formula (7) is coupled with the lower sideband reference optical signal output by the optical filter (Interleaver) shown in formula (3) at the second optical coupler (OC3), and the beat frequency is input into the second optical detector (PD2). A frequency peak value can be observed at the oscilloscope (OSC), and the peak frequency is f c1 -f c2 +kτ-f LO The chirp term kt is successfully eliminated. To measure the distance between the two targets, the above steps are repeated for the two targets. Since the distances between the two targets and the radar transmitter are different, the transmission delay τ is different, which results in a difference in the frequency peak value observed by the final oscilloscope (OSC). Denote the frequency peak value as Δf, and the distance L between the two targets is obtained as follows: At this point, the system has completed the sensing ranging and communication functions.

2. The millimeter wave communication and sensing integrated system of claim 1, wherein, The sensing-communication signal using time division multiplexing is equivalent to inserting a block-shaped pilot.

3. The millimeter wave communication and sensing integrated system of claim 1, wherein, The communication signal is a multi-carrier OFDM signal, and each subcarrier uses 16QAM modulation; the sensing signal is a linear frequency modulation LFM signal.

4. The millimeter wave communication and sensing integrated system of claim 1, wherein, By using the photon beat frequency technology, the broadband LFM signal and the communication signal are generated through one-time electric-optical-electric conversion, so as to realize high-speed communication and high-resolution sensing.

5. The millimeter wave communication and sensing integrated system of claim 1, wherein, The communication and sensing functions share the equipment, so as to avoid the waste of hardware resources.

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