Communication and distance measurement integrated laser radar system based on orthogonal chirp division multiplexing

Abstract

The invention relates to the technical field of communication, and provides a communication and distance measurement integrated laser radar system based on orthogonal chirp division multiplexing, which comprises a transmitter used for generating an orthogonal chirp division multiplexing OCDM optical signal which carries communication data and has superposed N orthogonal chirp subcarriers with a frequency modulated continuous wave (FMCW) distance measurement function through inverse Fresnel transform, the N / 2th sub-carrier in the N orthogonal chirp sub-carriers is specially used for ranging, and other sub-carriers are used for communication after being isolated by a guard band, so that multiplexing of communication and ranging functions is realized; the free space optical transmission module is used for transmitting the OCDM optical signal to a user terminal through a free space optical FSO channel; the user terminal is used for extracting communication data from the received OCDM optical signal through coherent demodulation; and the FMCW ranging receiver is used for acquiring distance information from the OCDM optical signal reflected from the detected target through beat frequency detection. The system provided by the invention can perform integrated efficient communication and accurate distance measurement.

Description

Technical Field

[0001] The present invention relates to the field of communication technologies, and particularly to a communication and ranging integrated lidar system based on orthogonal chirp division multiplexing. Background Art

[0002] Currently, in order to effectively improve spectrum and hardware efficiency and adapt to the future wireless network's ability to provide both communication and sensing, the industry has proposed relevant technical solutions for integrating free space optics (FSO) and lidar to achieve integrated sensing and communication (ISAC). Most of the research focuses on the integrated waveform design at the physical layer, mainly including the following solutions: 1) The integrated communication and sensing solution based on lidar waveforms, that is, through pulse sequence sensing and pulse position modulation methods, providing both sensing and communication capabilities for lidar. In addition, it also includes modulating the message encoded with pseudo-random noise codes onto the phase of the subcarriers transmitted by the sub-carriers, so that the phase-shifted lidar has communication capabilities; 2) The integrated communication and sensing solution based on communication waveforms, that is, applying the classical communication waveform orthogonal frequency division multiplexing (OFDM) as the integrated waveform to lidar. OFDM realizes ranging capabilities by measuring the time delay of signal propagation or the phase offset between sub-carriers and combining channel estimation characteristics.

[0003] In the above-mentioned prior art solutions, the integrated communication and sensing solutions based on lidar waveforms usually focus on pulses or single-carrier continuous waves, which limits the achievable communication rate and makes them vulnerable to non-linear distortions in optical systems. While the integrated communication and sensing solutions based on communication waveforms will reduce ranging accuracy. Summary of the Invention

[0004] The present application provides a communication and ranging integrated lidar system based on orthogonal chirp division multiplexing, which can perform efficient integrated communication and precise ranging.

[0005] The present application provides a communication and ranging integrated lidar system based on orthogonal chirp division multiplexing, the system includes: A transmitter, configured to generate an orthogonal chirp division multiplexing (OCDM) optical signal superimposed with N orthogonal chirp sub-carriers carrying communication data and having a frequency-modulated continuous wave (FMCW) ranging function through inverse Fresnel transform. The N / 2th sub-carrier among the N orthogonal chirp sub-carriers is dedicated to ranging, and the remaining sub-carriers are used for communication after being isolated by guard bands, so as to realize the multiplexing of communication and ranging functions by dynamically allocating sub-carrier power; A free-space optical transmission module for transmitting the OCDM optical signal to a user terminal through a free-space optical (FSO) channel; A user terminal for extracting communication data from the received OCDM optical signal through coherent demodulation; An FMCW ranging receiver for obtaining distance information from the OCDM optical signal reflected by a target to be measured through beat frequency detection.

[0006] As can be seen from the technical solutions provided in the present application above, on the one hand, the present application adopts all-optical signal processing and directly mixes signals using an optical coupler, eliminating a large number of electronic signal processing links, reducing the system power consumption, and being more suitable for low-power application scenarios. Since the use of complex radio frequency digital signal processing modules is reduced, the hardware cost can be reduced, and at the same time, the system stability is improved; on the other hand, through the optimized design of the OCDM waveform, the communication and ranging functions share the same set of optical hardware, reducing the device volume and complexity, and being more suitable for miniaturized and integrated devices. The optical signal processing avoids the electromagnetic interference problem of electronic devices, enabling the system to still work stably in a complex environment; on the third hand, the OCDM waveform is redesigned to adapt to the FSO-ISAC system, which can utilize the high ranging accuracy of FMCW and the excellent communication performance of OCDM, and can be applied to lidar in vehicle networking to achieve high-speed communication and high-precision ranging simultaneously, improving the safety of autonomous driving. Description of the Drawings

[0007] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0008] Figure 1 It is a schematic diagram of an integrated communication and ranging lidar system based on orthogonal chirp division multiplexing provided by an embodiment of the present application; Figure 2 It is a schematic diagram of an integrated communication and ranging lidar system based on orthogonal chirp division multiplexing provided by another embodiment of the present application; Figure 3 It is a schematic diagram of an integrated communication and ranging lidar system based on orthogonal chirp division multiplexing provided by another embodiment of the present application; Figure 4 It is a schematic diagram of an integrated communication and ranging lidar system based on orthogonal chirp division multiplexing provided by another embodiment of the present application; Figure 5It is a schematic diagram of a communication and ranging integrated lidar system based on orthogonal chirp division multiplexing provided by another embodiment of the present application; Figure 6 It is a schematic diagram of a communication and ranging integrated lidar system based on orthogonal chirp division multiplexing provided by another embodiment of the present application. Detailed implementation manners

[0009] Next, the technical solutions in the embodiments of the present application will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the protection scope of the present application.

[0010] In this specification, adjectives such as first and second can only be used to distinguish one element or action from another element or action, and do not necessarily require or imply any actual such relationship or order. Where circumstances permit, reference to an element or component or step (etc.) should not be construed as being limited to only one of the elements, components, or steps, but can be one or more of the elements, components, or steps, etc.

[0011] In this specification, for ease of description, the dimensions of the various parts shown in the drawings are not drawn according to actual proportional relationships.

[0012] To effectively improve the spectral and hardware efficiency and adapt to future wireless networks with the ability to provide both communication and sensing, the industry has proposed relevant technical solutions for integrating Free Space Optics (FSO) and lidar to achieve Integrated Sensing and Communication (ISAC). Most of the research focuses of these existing technical solutions are on the integrated waveform design at the physical layer, mainly including the following solutions: 1) The integrated communication and sensing solution based on lidar waveforms, that is, through pulse sequence sensing and pulse position modulation methods, providing both sensing and communication capabilities for lidar. In addition, it also includes modulating the message encoded with pseudo-random noise code to the phase of the subcarrier transmitted by the sub-carrier, so that the phase-shifted lidar has communication capabilities; 2) The integrated communication and sensing solution based on communication waveforms, that is, applying the classical communication waveform Orthogonal Frequency Division Multiplexing (OFDM) as the integrated waveform to lidar. OFDM realizes the ranging ability by measuring the time delay of signal propagation or the phase offset between sub-carriers and combining the channel estimation characteristics. In the above existing technical solutions, the integrated communication and sensing solution based on lidar waveforms usually focuses on pulses or single-carrier continuous waves, which limits the achievable communication rate and makes them vulnerable to the influence of non-linear distortion in the optical system, while the integrated communication and sensing solution based on communication waveforms will reduce the ranging accuracy.

[0013] In view of the above problems of the existing technology, this application proposes a lidar system for integrated communication and ranging based on orthogonal chirp division multiplexing. The schematic structural diagram is as shown in the appendix Figure 1 and mainly includes a transmitter 101, a free space optical transmission module 102, a user terminal 103, and an FMCW ranging receiver 104, which are described in detail as follows: The transmitter 101 is used to generate an Orthogonal Chirp Division Multiplexing (OCDM) optical signal with N orthogonal chirp sub-carriers superimposed, which carries communication data and has a Frequency Modulated Continuous Wave (FMCW) ranging function through inverse Fresnel transform. Among them, the N / 2th sub-carrier of the N orthogonal chirp sub-carriers is dedicated to ranging, and the remaining sub-carriers are used for communication after being isolated by guard bands, so as to realize the multiplexing of communication and ranging functions by dynamically allocating sub-carrier power.

[0014] In the above embodiments, an orthogonal hybrid waveform in the time domain is generated through an inverse Fresnel transform. Utilizing the time-frequency double orthogonality of chirped subcarriers, the OCDM waveform design is completed. The time-frequency orthogonality of the chirped subcarriers enables the communication subcarriers to overlap in the frequency domain without interfering with the integrity of the time-domain waveform of the ranging subcarriers. Thus, on the premise of sharing hardware resources, multi-carrier high-speed communication and FMCW high-precision ranging are synchronously achieved. The guard band isolation and power dynamic allocation mechanism effectively suppress the mutual interference between communication data and ranging data, avoiding the performance degradation caused by functional conflicts in traditional solutions.

[0015] It should be noted that, in order to enable ISAC to use the same waveform for ranging, this application studies the OCDM-assisted FMCW waveform design by adaptively selecting the subcarriers of the OCDM signal. That is, the subcarriers of each OCDM signal are regarded as a chirp signal. An OCDM symbol consists of N subcarriers. The N / 2-th subcarrier is selected for FMCW ranging because it represents the complete chirp within the OCDM period. To reduce the interference between communication subcarriers (i.e., subcarriers for communication) and ranging subcarriers (i.e., subcarriers for ranging, which is also the N / 2-th subcarrier among N orthogonal chirped subcarriers), a guard band is added, and the power is redistributed to the ranging subcarriers. Therefore, the subcarrier power allocation, that is, the amplitude of the ISAC symbol, satisfies: , where, is the power redistributed to the ranging subcarrier, is the power of the communication subcarrier, is the power of a single subcarrier without power redistribution, and is the width of the guard band. To prevent the interference of communication subcarriers, the bandwidth of the guard band should satisfy , where

[0016] The free space optical transmission module 102 is used to transmit the OCDM optical signal to the user terminal through a free space optics (FSO) channel.

[0017] In the above embodiments, the OCDM optical signal realizes the physical layer multiplexing of communication data and ranging signals in the free space channel, which can not only ensure the waveform integrity and support mobile ranging, but also improve the utilization rate of spectrum and hardware resources.

[0018] The user terminal 103 is used to extract communication data from the received OCDM optical signal through coherent demodulation.

[0019] The FMCW ranging receiver 104 is used to obtain distance information from the OCDM optical signal reflected by the measured target through beat frequency detection.

[0020] In the above embodiment, the transmitter 101 directly generates an OCDM optical signal, the user terminal 103 extracts data through coherent demodulation, and the FMCW ranging receiver 104 relies on the beat frequency detection of the OCDM optical signal. This all-optical signal processing link not only allows the communication and ranging functions to share the optical carrier generation, modulation and transmission links, reduces the hardware redundancy of independent functional modules, and reduces the system complexity and volume, but also can reduce the electrical domain conversion link, avoid electromagnetic interference and noise introduced by electronic devices, and enhance the operation stability in complex environments (such as strong electromagnetic fields and high temperatures).

[0021] From the above attached Figure 1 From the example of the integrated laser radar system for communication and ranging based on orthogonal chirp division multiplexing, it can be seen that, on the one hand, the system adopts all-optical signal processing and uses optical couplers to directly mix signals, which saves a lot of electronic signal processing links, reduces the energy consumption of the system and is more suitable for low-power application scenarios. Since the use of complex RF digital signal processing modules is reduced, the hardware cost can be reduced and the system stability is improved. On the other hand, through the optimization design of OCDM waveform, the communication and ranging functions share the same set of optical hardware, which reduces the size and complexity of the equipment and is more suitable for miniaturized and integrated equipment. Optical signal processing avoids the electromagnetic interference problem of electronic devices, so that the system can still work stably in complex environments. Thirdly, the OCDM waveform is redesigned to adapt to the FSO-ISAC system, which can utilize the high ranging accuracy of FMCW and the excellent communication performance of OCDM, and can be applied to the Internet of Vehicles laser radar to achieve high-speed communication and high-precision ranging simultaneously, thereby improving the safety of autonomous driving.

[0022] See also Figure 2 , is a communication and ranging integrated laser radar system based on orthogonal chirp division multiplexing provided by another embodiment of the present application, wherein the transmitter 101 includes a first serial-to-parallel conversion module 201, an orthogonal amplitude modulation module 202, an inverse Fresnel transformation module 203, an up-conversion module 204 and a Mach-Zehnder modulator 205, which are described in detail as follows: The first serial-to-parallel conversion module 201 is used to convert the input bit stream into N Parallel data.

[0023] The quadrature amplitude modulation mapping module 202 is used to N Each data in the parallel data is mapped to a complex symbol x ( k ).

[0024] Inverse Fresnel transform module 203, used to transform complex symbolsx ( k ) is converted into a time-domain OCDM signal.

[0025] Specifically, the time-domain OCDM signal output by the inverse Fresnel transform module is expressed as: , where is the k th chirp waveform and , the T is the symbol period, N is the total number of subcarriers, x ( k ) is the complex symbol modulated by the k th chirp subcarrier.

[0026] The up-conversion module 204 is used to modulate the time-domain OCDM signal onto a radio-frequency carrier to obtain a radio-frequency OCDM signal.

[0027] The Mach-Zehnder modulator 205 is used to load the radio-frequency OCDM signal onto the laser carrier.

[0028] In the embodiment of the present application, the laser carrier is the laser carrier provided by the first laser of the transmitter 101. The Mach-Zehnder modulator 205 loads the radio-frequency OCDM signal onto the laser carrier to generate an optical double-sideband signal with suppressed carrier. It should be noted that in order to support data communication, in the present application, by appropriately adjusting the bias voltage of the Mach-Zehnder Modulator (MZM) 205, OCDM is carried by the radio frequency (RF) f , that is, the up-conversion module 204 modulates the time-domain OCDM signal onto a radio-frequency carrier to obtain a radio-frequency OCDM signal, and drives the Mach-Zehnder modulator 205 to generate an optical double-sideband signal with suppressed carrier.

[0029] Please refer to Figure 3 , which is a communication and ranging integrated lidar system based on orthogonal chirp division multiplexing provided by another embodiment of the present application. On the basis of the transmitter 101 in the Figure 2 example, it further includes an erbium-doped fiber amplifier 301, a first optical coupler 302, and a circulator 303, which are described in detail as follows: The erbium-doped fiber amplifier 301 is used to increase the output optical power.

[0030] From Figure 3 , it can be seen that the input end of the erbium-doped fiber amplifier 301 is connected to the output end of the Mach-Zehnder modulator 205. Therefore, the erbium-doped fiber amplifier 301 increases the output power of the optical double-sideband signal.

[0031] The first optical coupler 302 is configured to split the OCDM optical signal generated by the transmitter 101 and transmit it to the free-space optical channel and the second optical coupler of the FMCW ranging receiver 104 as the local reference light.

[0032] In other words, the first optical coupler 302 splits the OCDM optical signal generated by the transmitter 101 into two paths. One path is transmitted to the circulator and sent to the user terminal through the free-space optical channel, and the other path is transmitted to the second optical coupler of the FMCW ranging receiver as the local reference light.

[0033] The circulator 303 is configured to isolate the OCDM optical signal transmitted by the transmitter 101 to the free-space optical channel from the OCDM optical signal reflected from the target under test and received by the FMCW ranging receiver 104.

[0034] In other words, on the one hand, the circulator 303 transmits the OCDM optical signal (carrying communication data) generated by the transmitter 101 to the user terminal through the free-space optical channel. On the other hand, the circulator 303 guides the OCDM optical signal reflected from the target under test from the free-space optical channel to the second optical coupler of the FMCW ranging receiver 104.

[0035] Please refer to Figure 4 , which is a communication and ranging integrated lidar system based on orthogonal chirp division multiplexing provided by another embodiment of the present application. The FMCW ranging receiver 104 includes a second optical coupler 401, a first photodetector 402, a first frequency detector 403, and a distance calculation module 404, which are described in detail as follows: The second optical coupler 401 is configured to combine the OCDM optical signal reflected from the target under test with the local reference light from the first optical coupler of the transmitter 101. The first photodetector 402 is configured to mix the OCDM optical signal reflected from the target under test with the local reference light of the transmitter 101 to obtain a beat signal. The first frequency detector 403 is configured to perform fast Fourier transform analysis on the beat signal to extract , where is the beat frequency between the OCDM optical signal reflected from the target under test and the local reference light generated by the transmitter 101. The distance calculation module 404 is configured to calculate the distance of the target under test according to the formula where c is the speed of light, n is the refractive index of the medium, representing the ratio of the speed of light in a vacuum to the speed of light in the medium, B is the sweep bandwidth.

[0036] Furthermore, the symbol period of the OCDM optical signal​T Synchronized with the sweep period of the FMCW ranging receiver and satisfying: , where is the maximum detection distance, B is the sweep bandwidth, is the bandwidth of the guard band.

[0037] Please refer to Figure 5 , which is a communication and ranging integrated lidar system based on orthogonal chirp division multiplexing provided by another embodiment of the present application. Its user terminal 103 includes a second laser 501, a second photodetector 502, and a Fresnel transform module 503, which are described in detail as follows: The second laser 501 is used to generate a local reference light for coherent demodulation; The second photodetector 502 is used to perform coherent mixing on the received OCDM optical signal and the local reference light and eliminate the common mode noise; The Fresnel transform module 503 is used to recover communication symbols. Specifically, after the output of the Fresnel transform module 503 undergoes carrier demodulation and QAM inverse mapping, the bit stream is restored through a parallel-to-serial conversion module.

[0038] From Figure 5 's example, on the side of the user terminal 103, the received signal is demodulated using the standard OCDM method. After being processed by the Fresnel transform module 503, due to the orthogonality of OCDM, the communication subcarriers will be "filtered out".

[0039] Please refer to Figure 6 , which is a communication and ranging integrated lidar system based on orthogonal chirp division multiplexing provided by another embodiment of the present application. Figure 6 The first laser 602 in

[0040] provides a laser carrier to the Mach-Zehnder modulator 205. The carrier demodulation module 605 and the quadrature amplitude demodulation module 606 respectively complete the inverse functions of the Mach-Zehnder modulator 205 and the quadrature amplitude modulation mapping module 202. Figures 1 to 6 Any of the above 1) Intelligent transportation and mobile vehicles: In the field of autonomous driving, the above Figures 1 to 6The integrated laser radar system based on orthogonal chirp multiplexing for communication and ranging in any example generates a high-precision three-dimensional environmental map in real time through laser radar, detects obstacles and measures distances, and uses laser communication to transmit real-time data (such as vehicle position, speed, and path planning) with surrounding vehicles, roadside units, or cloud platforms at high speed, to achieve multi-vehicle collaborative obstacle avoidance, dynamic formation driving, and intersection conflict warning. For example, in extreme weather such as heavy rain, vehicles can use laser radar to penetrate rain and fog to perceive the environment, and broadcast key data (such as landslide information ahead) to nearby vehicles through laser communication to avoid chain accidents. The drone field combines obstacle avoidance navigation with real-time communication. For example, when a logistics drone flies in a complex urban environment, it can not only accurately avoid obstacles such as high-voltage lines, but also synchronize the delivery status and battery remaining to the control center through laser links, and even receive emergency reroute instructions.

[0041] 2) Industrial Automation and Smart City Management: In industrial scenarios, the above Figures 1 to 6 Any example of an integrated laser radar system based on orthogonal chirp multiplexing for communication and ranging can enable an automated guided vehicle to use laser radar to achieve centimeter-level positioning and navigation, while transmitting information such as material handling progress and equipment failure warnings to the central control system in real time through optical communication, supporting the factory to dynamically adjust the production rhythm. For example, in an automobile manufacturing workshop, an automated guided vehicle can scan the assembly status of parts while moving, and instantly upload data to the cloud for quality analysis. In terms of smart cities, roadside laser radar units can monitor traffic flow, pedestrian behavior, and road anomalies (such as potholes) around the clock, and aggregate data to the city brain through high-speed optical communication networks for real-time control of traffic lights, optimization of bus scheduling, or triggering municipal maintenance responses. In addition, in the deformation monitoring of infrastructure such as bridges and tunnels, laser radar can detect millimeter-level structural changes, and simultaneously encrypt and transmit hidden danger data to the management platform to prevent major safety accidents.

[0042] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application is described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application. The specific implementation methods described above further describe the purpose, technical solutions and beneficial effects of the present application in detail. It should be understood that the above description is only the specific implementation method of the present application, and is not used to limit the protection scope of the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present invention.

Claims

1. A communication and ranging integrated lidar system based on orthogonal chirp division multiplexing, characterized in that, Comprising: A transmitter, configured to generate an Orthogonal Chirp Division Multiplexing (OCDM) optical signal carrying communication data and having a Frequency Modulated Continuous Wave (FMCW) ranging function, which is a superposition of N orthogonal chirp subcarriers, through an inverse Fresnel transform. The N / 2-th subcarrier among the N orthogonal chirp subcarriers is dedicated to ranging, and the remaining subcarriers are used for communication after being isolated by guard bands, so as to realize the multiplexing of communication and ranging functions by dynamically allocating subcarrier power; A free space optical transmission module, configured to transmit the OCDM optical signal to a user terminal through a free space optical (FSO) channel; A user terminal, configured to extract communication data from the received OCDM optical signal through coherent demodulation; An FMCW ranging receiver, configured to obtain distance information from the OCDM optical signal reflected by a target to be measured through beat frequency detection.

2. The integrated communication and ranging lidar system based on orthogonal chirp division multiplexing according to claim 1, wherein The transmitter includes: A first serial-to-parallel conversion module, configured to convert an input bit stream into N parallel data streams; Quadrature amplitude modulation mapping module, used to map each path of data in the N-path parallel data into complex symbols x ( k ); An inverse Fresnel transform module, configured to convert the complex symbol x(k) into a time-domain OCDM signal; An up-conversion module, configured to modulate the time-domain OCDM signal onto a radio frequency carrier to obtain a radio frequency OCDM signal; A Mach-Zehnder modulator, configured to load the radio frequency OCDM signal onto a laser carrier.

3. The integrated communication and ranging lidar system based on orthogonal chirp division multiplexing according to claim 2, characterized in that, The time-domain OCDM signal output by the inverse Fresnel transform module is expressed as: , where the is the k th chirp waveform and , where the T is the OCDM symbol period or the sweep period, and the N is the total number of subcarriers.

4. The integrated communication and ranging lidar system based on orthogonal chirp division multiplexing according to claim 3, wherein The subcarrier power distribution satisfies: ， The is the ranging subcarrier power, and the is the communication subcarrier power, and the is the width of the guard band.

5. The integrated communication and ranging lidar system based on orthogonal chirp division multiplexing according to claim 4, wherein The bandwidth of the protective belt Satisfies: ， The beat frequency between the OCDM optical signal reflected by the target to be measured and the local reference light generated by the transmitter.

6. The integrated communication and ranging lidar system based on orthogonal chirp division multiplexing according to claim 2, wherein The transmitter further includes: An erbium-doped fiber amplifier, configured to enhance the output optical power; A first optical coupler, configured to split and transmit the OCDM optical signal generated by the transmitter to a second optical coupler of the free space optical channel and the FMCW ranging receiver as a local reference light; A circulator, configured to isolate the OCDM optical signal sent by the transmitter to the free space optical channel from the OCDM optical signal received by the FMCW ranging receiver and reflected by the target to be measured.

7. The integrated communication and ranging lidar system based on orthogonal chirp division multiplexing according to claim 1, wherein The FMCW ranging receiver includes: A second optical coupler, configured to combine the OCDM optical signal reflected by the target to be measured with the local reference light from the first optical coupler of the transmitter; A first photodetector, configured to mix the OCDM optical signal reflected by the target to be measured with the local reference light of the transmitter to obtain a beat frequency signal; A first frequency detector for performing fast Fourier transform analysis on the beat signal to extract , where the is the beat frequency between the OCDM optical signal reflected by the target under test and the local reference light generated by the transmitter; A distance calculation module, which is used to calculate according to the formula the distance of the target to be measured, where c is the speed of light, and n is the refractive index of the medium, and B is the swept frequency bandwidth, and T is the symbol period or swept frequency period of the OCDM optical signal.

8. The integrated communication and ranging lidar system based on orthogonal chirp division multiplexing according to claim 1, wherein The user terminal includes: A second laser, configured to generate a local reference light for coherent demodulation; A second photodetector, configured to perform coherent mixing on the received OCDM optical signal and the local reference light and eliminate common mode noise; A Fresnel transform module, configured to recover communication symbols.

9. The integrated communication and ranging lidar system based on orthogonal chirp division multiplexing according to claim 8, wherein, After the output of the Fresnel transform module undergoes carrier demodulation and QAM inverse mapping, the bit stream is restored through a parallel-to-serial conversion module.

10. The integrated communication and ranging lidar system based on orthogonal chirp division multiplexing according to claim 1, characterized in that, The symbol period of the OCDM optical signal T is synchronized with the sweep period of the FMCW ranging receiver and satisfies: , where the is the maximum detection range, and the B is the sweep bandwidth, and the is the bandwidth of the guard band.

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