Communication and ranging integrated lidar system based on orthogonal chirp division multiplexing

Abstract

The present application relates to the field of communication technology and provides an integrated communication and ranging lidar system based on orthogonal chirp division multiplexing, including: a transmitter for generating an orthogonal chirp division multiplexing (OCDM) optical signal carrying communication data and having a frequency modulated continuous wave (FMCW) ranging function by superimposing N orthogonal chirped subcarriers through an inverse Fresnel transform, wherein the N / 2th subcarrier of the N orthogonal chirped subcarriers is dedicated to ranging, and the remaining subcarriers are isolated by a guard band and used for communication, thereby multiplexing the communication and ranging functions; a free-space optical transmission module for transmitting the OCDM optical signal to a user terminal via a free-space optical (FSO) channel; a user terminal for extracting communication data from the received OCDM optical signal through coherent demodulation; and an FMCW ranging receiver for obtaining distance information from the OCDM optical signal reflected by the target under test through beat frequency detection. The system provided by the present application can achieve integrated efficient communication and precise ranging.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and in particular to a communication and ranging integrated laser radar system based on orthogonal chirp division multiplexing. Background Art

[0002] To effectively improve spectrum and hardware efficiency and adapt to future wireless networks providing both communication and perception capabilities, the industry has proposed technical solutions that combine free-space optics (FSO) with lidar to achieve integrated sensing and communication (ISAC). These existing technical solutions primarily focus on integrated waveform design at the physical layer, including the following:

[0003] 1) A synaesthesia-integrated solution based on the lidar waveform, which provides both sensing and communication capabilities for the lidar through pulse train sensing and pulse position modulation. Furthermore, this solution includes modulating a pseudorandom noise code-encoded message onto the phase of the subcarrier transmitted by the subcarrier, enabling phase-shifted lidar to communicate.

[0004] 2) A communication waveform-based synaesthesia integration solution. This involves applying the classic communication waveform, orthogonal frequency division multiplexing (OFDM), to lidar as an integrated waveform. OFDM achieves ranging capabilities by measuring the time delay of signal propagation or the phase offset between subcarriers, combined with channel estimation characteristics.

[0005] The above-mentioned existing technical solutions based on laser radar waveforms generally focus on pulses or single-carrier continuous waves, which limits their achievable communication rates and makes them susceptible to nonlinear distortion in optical systems. The synaesthesia integration solutions based on communication waveforms will reduce the ranging accuracy. Summary of the Invention

[0006] The present application provides a communication and ranging integrated lidar system based on orthogonal chirp division multiplexing, which can perform integrated efficient communication and precise ranging.

[0007] The present application provides a communication and ranging integrated laser radar system based on orthogonal chirp division multiplexing, the system comprising:

[0008] A transmitter configured to generate, through an inverse Fresnel transform, an orthogonal chirped subcarrier multiplexing (OCDM) optical signal carrying communication data and having a frequency modulated continuous wave (FMCW) ranging function, wherein the N / 2th subcarrier of the N orthogonal chirped subcarriers is dedicated to ranging, and the remaining subcarriers are isolated by a guard band and used for communication, so as to achieve multiplexing of communication and ranging functions by dynamically allocating subcarrier power;

[0009] A free space optical transmission module, configured to transmit the OCDM optical signal to a user terminal via a free space optical FSO channel;

[0010] A user terminal, configured to extract communication data from the received OCDM optical signal by coherent demodulation;

[0011] The FMCW ranging receiver is used to obtain distance information from the OCDM optical signal reflected by the target through beat frequency detection.

[0012] From the technical solutions provided by the present application, it can be seen that, on the one hand, the present application adopts all-optical signal processing and uses optical couplers to directly mix signals, thereby eliminating a large number of electronic signal processing links, reducing system energy consumption, and being more suitable for low-power application scenarios. Since the use of complex RF digital signal processing modules is reduced, hardware costs can be reduced while improving system stability. On the other hand, the present application optimizes the design of the OCDM waveform so that communication and ranging functions share the same set of optical hardware, reducing the size and complexity of the equipment and making it more suitable for miniaturized and integrated equipment. Optical signal processing avoids electromagnetic interference problems of electronic devices, allowing the system to 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 vehicle network lidar to achieve high-speed communication and high-precision ranging simultaneously, thereby improving the safety of autonomous driving. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0014] Figure 1 Schematic diagram of a communication and ranging integrated lidar system based on orthogonal chirp division multiplexing provided in an embodiment of the present application;

[0015] Figure 2 Schematic diagram of a communication and ranging integrated lidar system based on orthogonal chirp division multiplexing provided by another embodiment of the present application;

[0016] Figure 3 Schematic diagram of a communication and ranging integrated lidar system based on orthogonal chirp division multiplexing provided by another embodiment of the present application;

[0017] Figure 4 Schematic diagram of a communication and ranging integrated lidar system based on orthogonal chirp division multiplexing provided by another embodiment of the present application;

[0018] Figure 5 Schematic diagram of a communication and ranging integrated lidar system based on orthogonal chirp division multiplexing provided by another embodiment of the present application;

[0019] Figure 6 This is a schematic diagram of an integrated laser radar system for communication and ranging based on orthogonal chirp division multiplexing provided in another embodiment of the present application. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0021] In this specification, adjectives such as first and second may be used only to distinguish one element or action from another element or action, without necessarily requiring or implying 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 may be one or more of the elements, components, or steps, etc.

[0022] In this specification, for the convenience of description, the sizes of various parts shown in the drawings are not drawn according to the actual proportions.

[0023] To effectively improve spectrum and hardware efficiency and adapt to future wireless networks providing both communication and perception capabilities, the industry has proposed technologies that combine free-space optics (FSO) with lidar to achieve integrated sensing and communication (ISAC). These existing solutions primarily focus on integrated waveform design at the physical layer, including the following: 1) LiDAR waveform-based synaesthesia integration, which uses pulse train sensing and pulse position modulation to provide both sensing and communication capabilities for lidars. Furthermore, this approach modulates pseudorandom noise (PNR)-encoded messages onto the phases of transmitted subcarriers, enabling phase-shifted lidars to communicate. 2) Communication waveform-based synaesthesia integration, which applies the classic communication waveform, orthogonal frequency division multiplexing (OFDM), to lidars as an integrated waveform. OFDM achieves ranging capabilities by measuring signal propagation time delays or inter-subcarrier phase offsets, combined with channel estimation properties. The above-mentioned existing technical solutions based on laser radar waveforms generally focus on pulses or single-carrier continuous waves, which limits their achievable communication rates and makes them susceptible to nonlinear distortion in optical systems. The synaesthesia integration solutions based on communication waveforms will reduce the ranging accuracy.

[0024] In view of the above problems of the prior art, this application proposes a communication and ranging integrated lidar system based on orthogonal chirp division multiplexing, the structural diagram of which is shown in the attached figure. Figure 1 As shown, it 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:

[0025] Transmitter 101 is configured to generate an orthogonal chirp division multiplexing (OCDM) optical signal using an inverse Fresnel transform (ITT) that carries communication data and has a frequency modulated continuous wave (FMCW) ranging function. The signal is composed of N orthogonal chirped subcarriers superimposed on each other, each carrying communication data. The N / 2th subcarrier of the N orthogonal chirped subcarriers is dedicated to ranging, and the remaining subcarriers are isolated by a guard band and used for communication. This allows for multiplexing of communication and ranging functions by dynamically allocating subcarrier power.

[0026] In the above embodiment, an inverse Fresnel transform is used to generate a time-domain orthogonal hybrid waveform, leveraging the dual orthogonality of chirped subcarriers in both the time and frequency domains to achieve OCDM waveform design. The time-frequency orthogonality of chirped subcarriers allows communication subcarriers to overlap in the frequency domain without interfering with the time-domain waveform integrity of the ranging subcarriers. This allows for simultaneous implementation of multi-carrier high-speed communication and FMCW high-precision ranging while sharing hardware resources. Guard band isolation and dynamic power allocation effectively suppress mutual interference between communication and ranging data, avoiding the performance compromise often associated with functional conflicts in traditional solutions.

[0027] It should be noted that in order to enable the 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, each subcarrier of the OCDM signal is regarded as a linear frequency modulation signal. The OCDM symbol consists of N subcarriers, and the N / 2 subcarrier is selected for FMCW ranging because it represents the complete chirp within the OCDM period. In order to reduce the interference between the communication subcarrier (i.e., the subcarrier used for communication) and the ranging subcarrier (i.e., the subcarrier used for ranging, i.e., the N / 2 subcarrier among the N orthogonal chirped subcarriers), a guard band is added, in which the power is reallocated to the ranging subcarrier. Therefore, the subcarrier power allocation, i.e., the amplitude of the ISAC symbol, satisfies:

[0028] ,

[0029] in, is the power reallocated to the ranging subcarrier, is the power of the communication subcarrier, is the power of a single subcarrier without power reallocation, and Is the width of the guard band. In order to prevent interference from the communication subcarrier, the bandwidth of the guard band Should meet , is the beat frequency between the OCDM optical signal reflected by the target (eg, a car, a pedestrian, etc.) and the local reference light generated by the transmitter 101 .

[0030] The free space optical transmission module 102 is configured to transmit the OCDM optical signal to the user terminal via a free space optical (Free Space Optics, FSO) channel.

[0031] In the above embodiment, the OCDM optical signal implements physical layer multiplexing of communication data and ranging signals in a free space channel, which not only ensures waveform integrity and supports mobile ranging, but also improves spectrum and hardware resource utilization.

[0032] The user terminal 103 is configured to extract communication data from the received OCDM optical signal through coherent demodulation.

[0033] The FMCW ranging receiver 104 is configured to obtain distance information from the OCDM optical signal reflected by the target through beat frequency detection.

[0034] 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 beat frequency detection of the OCDM optical signal. This all-optical signal processing link not only allows communication and ranging functions to share the optical carrier generation, modulation, and transmission links, reducing hardware redundancy in independent functional modules and lowering system complexity and size, but also reduces electrical domain conversion steps, avoids electromagnetic interference and noise introduced by electronic components, and enhances operational stability in complex environments (such as strong electromagnetic fields and high temperatures).

[0035] From the above attached Figure 1 From the example of the integrated communication and ranging lidar system 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, eliminating a large number of electronic signal processing links, reducing system energy consumption, and making it more suitable for low-power application scenarios. Since the use of complex RF digital signal processing modules is reduced, hardware costs can be reduced while improving system stability. On the other hand, through the optimized design of OCDM waveform, the communication and ranging functions share the same set of optical hardware, reducing the size and complexity of the equipment, and making it 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 take advantage of the high ranging accuracy of FMCW and the excellent communication performance of OCDM, and can be applied to vehicle network lidar to achieve high-speed communication and high-precision ranging simultaneously, thereby improving the safety of autonomous driving.

[0036] 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. Its transmitter 101 includes a first serial-to-parallel conversion module 201, an orthogonal amplitude modulation module 202, an inverse Fresnel transform module 203, an up-conversion module 204, and a Mach-Zehnder modulator 205, as described in detail as follows:

[0037] The first serial-to-parallel conversion module 201 is used to convert the input bit stream into N Path parallel data.

[0038] 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 ).

[0039] Inverse Fresnel transform module 203 is used to transform the complex symbol x ( k ) is converted into a time-domain OCDM signal.

[0040] Specifically, the time domain OCDM signal output by the inverse Fresnel transform module is expressed as:

[0041] ,in, For the k A chirp waveform and ,Place T is the symbol period, N is the total number of subcarriers, x ( k ) is the k The complex symbols modulated by the chirp subcarriers.

[0042] The up-conversion module 204 is configured to modulate the time-domain OCDM signal onto a radio frequency carrier to obtain a radio frequency OCDM signal.

[0043] The Mach-Zehnder modulator 205 is used to load the radio frequency OCDM signal onto the laser carrier.

[0044] In the embodiment of the present application, the laser carrier is provided by the first laser of the transmitter 101, and the Mach-Zehnder modulator 205 loads the RF OCDM signal onto the laser carrier to generate an optical double-sideband signal with a suppressed carrier. It should be noted that in order to support data communication, the present application appropriately adjusts the bias voltage of the Mach-Zehnder Modulator (MZM) 205, and the OCDM is generated by the RF frequency (RF). f The carrier or 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 a suppressed carrier.

[0045] See also Figure 3 , is a communication and ranging integrated laser radar system based on orthogonal chirp division multiplexing provided by another embodiment of the present application, Figure 2 The exemplary transmitter 101 further includes an erbium-doped fiber amplifier 301, a first optical coupler 302, and a circulator 303, as detailed below:

[0046] The erbium-doped fiber amplifier 301 is used to increase the output optical power.

[0047] from Figure 3It 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-side band signal.

[0048] 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 local reference light.

[0049] 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 via the free space optical channel. The other path is transmitted to the second optical coupler of the FMCW ranging receiver as a local reference light.

[0050] The circulator 303 is used to isolate the OCDM optical signal sent by the transmitter 101 to the free space optical channel from the OCDM optical signal reflected from the measured target and received by the FMCW ranging receiver 104 .

[0051] In other words, the circulator 303 , on the one hand, transmits the OCDM optical signal (carrying communication data) generated by the transmitter 101 to the user terminal via the free-space optical channel, and on the other hand, guides the OCDM optical signal reflected by the target from the free-space optical channel to the second optical coupler of the FMCW ranging receiver 104 .

[0052] See also Figure 4 , 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 FMCW ranging receiver 104 thereof includes a second optical coupler 401, a first photodetector 402, a first frequency detector 403, and a distance calculation module 404, as described in detail as follows:

[0053] The second optical coupler 401 is used to combine the OCDM optical signal reflected from the target and the local reference light from the first optical coupler of the transmitter 101;

[0054] The first photodetector 402 is configured to mix the OCDM optical signal reflected by the target with the local reference light of the transmitter 101 to obtain a beat frequency signal;

[0055] The first frequency detector 403 is used to perform fast Fourier transform analysis on the beat frequency signal to extract ,in, is the beat frequency between the OCDM optical signal reflected by the target and the local reference light generated by the transmitter 101;

[0056] The distance calculation module 404 is used to calculate the distance according to the formula Calculate the distance to the target,

[0057] in, c is the speed of light, n is the refractive index of the medium, which represents the ratio of the speed of light in a vacuum to the speed of light in the medium. B is the sweep bandwidth.

[0058] Furthermore, the symbol period of the OCDM optical signal T Synchronize with the sweep cycle of the FMCW ranging receiver and satisfy:

[0059] ,in, is the maximum detection distance, B is the sweep bandwidth, is the bandwidth of the guard band.

[0060] See also Figure 5 , 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 user terminal 103 includes a second laser 501, a second photodetector 502, and a Fresnel transform module 503, as described in detail as follows:

[0061] A second laser 501 is used to generate local reference light for coherent demodulation;

[0062] a second photodetector 502, configured to coherently mix the received OCDM optical signal with the local reference light and eliminate common mode noise;

[0063] The Fresnel transform module 503 is used to restore communication symbols. Specifically, the output of the Fresnel transform module 503 is subjected to carrier demodulation and QAM inverse mapping, and then restored to a bit stream through the parallel-to-serial conversion module.

[0064] from Figure 5 As can be seen from the example, at the user terminal 103 side, the received signal is demodulated using the standard OCDM method. After being processed by the Fresnel transform module 503, the communication subcarriers will be "filtered out" due to the orthogonality of OCDM.

[0065] See also Figure 6 , is another embodiment of the present application, which provides an integrated laser radar system for communication and ranging based on orthogonal chirp multiplexing. Figure 6 The first laser 602 provides a laser carrier to the Mach-Zehnder modulator 205 , and 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 .

[0066] above Figures 1 to 6Any of the examples of integrated communication and ranging lidar systems based on orthogonal chirp division multiplexing significantly reduces system energy consumption and complexity through all-optical signal processing and OCDM waveform design, while also improving the synergy between communication and ranging. Its low cost, low power consumption, and high reliability make it directly applicable in fields such as intelligent transportation. Here are a few application scenarios:

[0067] 1) Intelligent transportation and mobile vehicles: In the field of autonomous driving, the above Figures 1 to 6 In any of these examples, an integrated lidar system with communication and ranging based on orthogonal chirp division multiplexing (OCDM) generates high-precision three-dimensional environmental maps in real time using lidar, detects obstacles, and measures distances. It also uses laser communication to transmit real-time data (such as vehicle position, speed, and path planning) to surrounding vehicles, roadside units, or cloud platforms at high speed, enabling multi-vehicle collaborative obstacle avoidance, dynamic platooning, and intersection collision warning. For example, in extreme weather conditions such as heavy rain, vehicles can use lidar to penetrate rain and fog to perceive the environment and broadcast critical data (such as information about landslides ahead) to nearby vehicles via laser communication, thus preventing chain reactions. In the drone sector, obstacle avoidance and navigation are combined with real-time communication. For example, logistics drones flying in complex urban environments can accurately avoid obstacles such as high-voltage power lines while simultaneously transmitting delivery status and battery life to a control center via laser links, and even receive emergency reroute instructions.

[0068] 2) Industrial Automation and Smart City Management: In industrial scenarios, the above Figures 1 to 6 In any of these examples, an integrated LiDAR system based on orthogonal chirp division multiplexing (OCDM) communication and ranging can enable automated guided vehicles (AGVs) to achieve centimeter-level positioning and navigation using LiDAR. It also transmits information such as material handling progress and equipment failure warnings to the central control system in real time via optical communications, enabling factories to dynamically adjust their production schedules. For example, in an automotive manufacturing workshop, an AGV can scan the assembly status of parts while on the move and instantly upload the data to the cloud for quality analysis. In smart cities, roadside LiDAR units can monitor traffic flow, pedestrian behavior, and road anomalies (such as potholes) around the clock, aggregating this data to the city's brain via high-speed optical communication networks for real-time traffic light control, optimized bus dispatch, or triggering municipal maintenance responses. Furthermore, in deformation monitoring of infrastructure such as bridges and tunnels, LiDAR can detect millimeter-level structural changes and simultaneously encrypt and transmit hidden danger data to a management platform to prevent major safety incidents.

[0069] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application. The specific implementation methods described above further explain 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 all be included in the protection scope of the present invention.

Claims

1. A communication and ranging integrated laser radar system based on orthogonal chirp division multiplexing, characterized in that: The system uses all-optical signal processing and OCDM waveform optimization design to enable communication and ranging functions to share the same set of optical hardware. The system includes: A transmitter configured to generate, through an inverse Fresnel transform, an orthogonal chirped subcarrier multiplexing (OCDM) optical signal carrying communication data and having a frequency modulated continuous wave (FMCW) ranging function, wherein the N / 2th subcarrier of the N orthogonal chirped subcarriers is dedicated to ranging, and the remaining subcarriers are isolated by a guard band and used for communication, so as to achieve 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 via a free space optical FSO channel; A user terminal, configured to extract communication data from the received OCDM optical signal by coherent demodulation; The FMCW ranging receiver is used to obtain distance information from the OCDM optical signal reflected by the target through beat frequency detection.

2. The communication and ranging integrated laser radar system based on orthogonal chirp division multiplexing according to claim 1 is characterized in that: The transmitter comprises: A first serial-to-parallel conversion module is used to convert an input bit stream into N parallel data; A quadrature amplitude modulation mapping module is used to map each of the N parallel data into a complex symbol 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; The Mach-Zehnder modulator is used to load the radio frequency OCDM signal onto a laser carrier.

3. The communication and ranging integrated laser radar system based on orthogonal chirp division multiplexing according to claim 2 is characterized in that: The time domain OCDM signal output by the inverse Fresnel transform module is expressed as: 0≤t<T, the Ψ k (t) is the kth chirp waveform and The T is the symbol period of the OCDM optical signal, and the N is the total number of subcarriers.

4. The communication and ranging integrated laser radar system based on orthogonal chirp division multiplexing according to claim 3 is characterized in that: The subcarrier power allocation satisfies: The P s is the ranging subcarrier power, the P c is the communication subcarrier power, the N GB is the width of the guard band.

5. The communication and ranging integrated laser radar system based on orthogonal chirp division multiplexing according to claim 4 is characterized in that: The bandwidth G of the guard band GB satisfy: G GB >f b , The f b It is the beat frequency between the OCDM optical signal reflected by the target and the local reference light generated by the transmitter.

6. The communication and ranging integrated laser radar system based on orthogonal chirp division multiplexing according to claim 2, characterized in that: The transmitter further comprises: Erbium-doped fiber amplifier, used to increase output optical power; a first optical coupler configured to split and transmit the OCDM optical signal generated by the transmitter to the free space optical channel and the second optical coupler of the FMCW ranging receiver as a local reference light; The circulator is used to isolate the OCDM optical signal sent by the transmitter to the free space optical channel from the OCDM optical signal reflected from the measured target and received by the FMCW ranging receiver.

7. The communication and ranging integrated laser radar system based on orthogonal chirp division multiplexing according to claim 1, characterized in that: The FMCW ranging receiver includes: a second optical coupler, configured to combine the OCDM optical signal reflected from 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 under test with the local reference light of the transmitter to obtain a beat frequency signal; The first frequency detector is used to perform fast Fourier transform analysis on the beat frequency signal to extract f b , the f b The beat frequency between the OCDM optical signal reflected by the target and the local reference light generated by the transmitter; Distance calculation module, used according to the formula The distance of the measured target is calculated, where c is the speed of light, n is the refractive index of the medium, B is the frequency sweep bandwidth, and T is the symbol period of the OCDM optical signal.

8. The communication and ranging integrated laser radar system based on orthogonal chirp division multiplexing according to claim 1, characterized in that: The user terminal includes: A second laser is used to generate local reference light for coherent demodulation; a second photodetector, configured to coherently mix the received OCDM optical signal with the local reference light and eliminate common mode noise; Fresnel transform module, used to recover communication symbols.

9. The communication and ranging integrated laser radar system based on orthogonal chirp division multiplexing according to claim 8, characterized in that: The output of the Fresnel transform module is subjected to carrier demodulation and QAM inverse mapping, and then restored to a bit stream through a parallel-to-serial conversion module.

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

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