A multi-user parallel laser-induced sound communication method and device based on array dynamic division and orthogonal coding

Abstract

This application provides a multi-user parallel laser acoustic communication method and apparatus based on dynamic array partitioning and orthogonal coding, solving the technical problems of poor real-time performance, severe spatial crosstalk between multiple beams, and unreliable unidirectional link communication in existing multi-user parallel communication methods. It includes acquiring the real-time position coordinates, unique identifier, and communication requirements of the target to be communicated with; dynamically partitioning the laser emission array to obtain virtual emission subarrays oriented to serve the corresponding target; matching the orthogonal code sequence corresponding to the unique identifier; spreading and modulating the user data stream to obtain a spread-spectrum digital signal; mapping this signal to obtain a multi-channel pulse control sequence; calculating the trigger time delay corresponding to each virtual emission subarray; simultaneously driving the laser emission units within each virtual emission subarray to emit laser pulses; and using the orthogonal code sequence for decoding and interference removal at the receiving end to achieve parallel communication. This application can be widely applied in the field of underwater acoustic communication technology.

Description

Technical Field

[0001] This application belongs to the field of underwater acoustic communication technology, and more specifically, relates to a multi-user parallel laser-induced acoustic communication method and device based on array dynamic partitioning and orthogonal coding. Background Technology

[0002] Laser-induced acoustic cross-medium communication technology utilizes a high-energy pulsed laser mounted on an aerial platform (such as a drone, aircraft, or satellite) to emit laser light towards the water-air interface. Through optical breakdown or thermoelastic expansion mechanisms, high-frequency broadband sound waves are excited in the water, enabling non-contact, one-way data transmission from the air to underwater targets. Compared to traditional radio communication (which suffers significant attenuation in seawater) and sonar buoy relay communication (which requires the deployment of physical equipment), laser-induced acoustic technology offers advantages such as high concealment, high mobility, and no need for pre-positioned surface facilities. It holds significant application value in underwater communication, underwater sensor network data exchange, and cross-medium collaborative command.

[0003] However, as underwater operations develop towards clustering and collaboration, existing laser acoustic communication technology has the following drawbacks when facing multi-user concurrent communication scenarios: First, the real-time performance of multi-target concurrency is poor. Existing laser acoustic communication uses a single-beam polling mechanism, which requires sending commands to multiple underwater targets in different directions in sequence. This results in a linear increase in communication latency with the number of targets, which cannot meet the high real-time synchronization and group calling requirements of cluster collaboration. Second, multi-beam spatial crosstalk is severe. Due to the low-frequency characteristics of laser acoustic communication, the sound wave wavelength is relatively long, and the diffraction effect is significant. When multiple underwater targets approach each other in space, the multiple acoustic beams generated by simultaneous excitation are prone to aliasing and interference, which leads to a sharp deterioration in the signal-to-interference-plus-noise ratio at the receiver. It is difficult to separate the useful signal from the superimposed signal, resulting in a high bit error rate or even communication link interruption. Thirdly, the unidirectional link lacks anti-interception and anti-interference capabilities. Air-to-water laser acoustic communication mostly adopts fixed coding modulation format, with single signal characteristics. The beam sidelobes are easily intercepted by non-cooperative parties. At the same time, there is a lack of orthogonal isolation means. Under the condition of malicious co-frequency acoustic interference, the communication is unreliable.

[0004] In summary, there is an urgent need to provide a multi-user parallel laser-induced acoustic communication method to solve the problems of poor real-time performance, severe spatial crosstalk of multiple beams, and unreliable one-way link communication in existing multi-user parallel communication. Summary of the Invention

[0005] The purpose of this application is to provide a multi-user parallel laser acoustic communication method and apparatus based on array dynamic partitioning and orthogonal coding, so as to solve the technical problems of poor real-time performance, severe spatial crosstalk of multiple beams and unreliable one-way link communication in the prior art.

[0006] To achieve the above objectives, a first aspect of this application provides a multi-user parallel laser-induced acoustic communication method based on array dynamic partitioning and orthogonal coding, comprising the following steps: The real-time location coordinates, unique identifier, and communication requirements of the target to be communicated are obtained. Based on the real-time location coordinates and communication requirements, the laser emission array is dynamically divided to obtain a virtual emission subarray that provides directional service to the corresponding target to be communicated. Based on the preset identity-code sequence mapping relationship, the orthogonal code sequence corresponding to the unique identity is matched, and the user data stream is spread spectrum modulated using the orthogonal code sequence to obtain the spread spectrum digital signal, which is then mapped to obtain a multi-channel pulse control sequence. The trigger time delay corresponding to each virtual transmitter subarray is calculated. Based on the multi-channel pulse control sequence and the trigger time delay, the laser emitting units in each virtual transmitter subarray are driven to emit laser pulses simultaneously. The receiving end uses orthogonal code sequences for decoding and interference removal to achieve parallel communication.

[0007] Preferably, the dynamic partitioning process includes: calculating the straight-line distance from the target to be communicated to the center of the laser emitting array; based on the principle of non-uniform resource allocation, allocating and determining the number of laser emitting units in the virtual emitting subarray according to the square of the straight-line distance from each target to be communicated to the center of the laser emitting array; and dynamically partitioning the laser emitting array to obtain virtual emitting subarrays that are oriented to serve the corresponding target to be communicated.

[0008] Preferably, the laser pulse waveforms corresponding to all the code chips are spliced ​​together in chronological order to obtain a multi-channel pulse control sequence; The formula for obtaining the laser pulse waveform is: ; In the formula, For the first individual code chip The laser pulse waveform, It is a rectangular pulse function. For chip cycle, This represents the pulse width.

[0009] Preferably, the process of calculating the trigger time delay corresponding to each virtual transmitting subarray includes: for each virtual transmitting subarray, based on the real-time position coordinates of the target to be communicated, calculating the trigger time delay of each laser emitting unit within the virtual transmitting subarray, using the following formula: ; In the formula, For the trigger time delay amount, The projection point of the laser emitting unit on the water surface to the first The acoustic range of the target to be communicated. The speed of sound in water, The optical path length from the laser emitting unit to the projection point on the water surface is given. The speed of light in air. This is the reference time constant used for global beam synchronization.

[0010] Preferably, the formula for determining the number of laser emitting units in the virtual emitting subarray is: ; In the formula, The number of laser emitting units, This represents the total number of units in the laser emitting array. For the first The straight-line distance from the target to be communicated to the center of the laser emitting array. This represents the rounding function.

[0011] Preferably, the geometric center of the virtual transmitter subarray is selected as the deployment area of ​​the virtual transmitter subarray to reduce signal interference; The process of calculating the geometric center of the virtual transmitting subarray includes: on the physical plane or spatial distribution of the laser transmitting array, a search algorithm is used to select the region that minimizes the scanning deflection angle of each virtual transmitting subarray to the corresponding target to be communicated, thus obtaining the geometric center of the virtual transmitting subarray.

[0012] Preferably, the decoding and interference removal process includes: performing cross-correlation operations on the received signal at the receiving end using orthogonal code sequences to filter out spatial overlap interference.

[0013] Preferably, when the virtual emission subarrays have overlapping areas in physical space, an array element reuse strategy is adopted to mark the laser emission units located in the overlapping areas as reuse units, thereby improving resource utilization.

[0014] Preferably, the signal driving the multiplexing unit is generated by performing linear superposition or optical power synthesis operations in the time domain on the multi-channel pulse control sequence involved, so that the multiplexing unit carries the information characteristics of multiple users while emitting laser pulse intensity.

[0015] A second aspect of this application provides a multi-user parallel laser acoustic communication device based on array dynamic partitioning and orthogonal coding, comprising: an airborne transmitter and an underwater receiver; The airborne transmitter includes several UAVs, each of which includes a main control unit, a situational awareness module, a cooperative communication module, a drive circuit, a pulsed laser, and a beam projection device; The input end of the main control unit is connected to the situational awareness module and the cooperative communication module to obtain the real-time position coordinates, unique identification and communication requirements of the target to be communicated. Based on the real-time position coordinates and communication requirements, the laser emission array is dynamically divided to obtain a virtual emission subarray that is oriented to serve the corresponding target to be communicated. The main control unit is connected to the pulsed laser through a drive circuit. It is used to match the orthogonal code sequence corresponding to the unique identity based on the preset identity-code sequence mapping relationship, and use the orthogonal code sequence to spread spectrum modulate the user data stream to obtain the spread digital signal. The spread digital signal is then mapped to obtain a multi-channel pulse control sequence. The trigger time delay corresponding to each virtual transmitter subarray is calculated. Based on the multi-channel pulse control sequence and the trigger time delay, the pulsed laser is driven to control the beam projection device to simultaneously drive the laser emission unit in each virtual transmitter subarray to emit laser pulses. The underwater receiver includes a signal processing terminal, an analog-to-digital converter, an analog front-end, and an underwater transducer; The underwater transducer is connected to the signal processing terminal via an analog front-end and an analog-to-digital converter. The underwater transducer is used to receive the acoustic signal generated by laser pulse excitation, and the signal processing terminal is used to decode and remove interference from the digital signal converted by the analog-to-digital converter using orthogonal code sequences to achieve parallel communication.

[0016] The beneficial effects of this application are as follows: This application provides a multi-user parallel laser acoustic communication method and device based on array dynamic partitioning and orthogonal coding. First, by obtaining the real-time position coordinates, unique identifier, and communication requirements of the target to be communicated, the laser emission array is dynamically partitioned based on the real-time position coordinates and communication requirements, virtualizing a single physical array into multiple parallel sub-apertures. This abandons the traditional time-division polling mode and realizes simultaneous data transmission to multiple underwater targets, significantly improving system throughput and the real-time performance of cluster control, and realizing multi-user real-time parallel communication. Next, based on the preset identity-code sequence mapping relationship, the orthogonal code sequence corresponding to the unique identifier is matched. At the same time, the orthogonal code sequence is used to spread spectrum modulation and mapping of the user data stream to obtain a multi-path pulse control sequence. By using the mechanism of combining orthogonal spread spectrum code domain mapping and unipolar pulse position modulation (PPM), the signal aliasing problem in the multi-beam overlap area is solved. Even if the sound beams overlap in physical space, the receiver can still effectively filter out interference through orthogonal decoding, ensuring communication reliability in high-density scenarios and effectively suppressing beam space crosstalk. Finally, the trigger time delay for each virtual transmitter subarray is calculated, and based on the multi-pulse control sequence and the trigger time delay, laser pulses are simultaneously emitted by the laser emission units within each virtual transmitter subarray. The receiver uses orthogonal code sequences for decoding and interference removal, achieving parallel communication and improving link security and energy efficiency. Furthermore, this application sets a distance-based non-uniform resource allocation principle during dynamic partitioning, and configures a time-synchronized codebook update mechanism for both the airborne transmitter and the underwater receiver. This solves the energy waste problem caused by the near-far effect and makes the signal exhibit pseudo-random noise characteristics, significantly enhancing the stealth and anti-interception capabilities of communication under feedback-free link conditions. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A schematic diagram of the overall process of a multi-user parallel laser acoustic communication method based on array dynamic partitioning and orthogonal coding provided in an embodiment of this application; Figure 2 This is a schematic diagram of the structure of a multi-user parallel laser acoustic communication device based on array dynamic partitioning and orthogonal coding, provided in an embodiment of this application. Detailed Implementation

[0019] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0020] This application provides a multi-user parallel laser acoustic communication method and apparatus based on array dynamic partitioning and orthogonal coding. First, the real-time position coordinates, unique identifiers, and communication requirements of multiple underwater targets to be communicated with are acquired. Based on a many-to-many mapping relationship, multiple distributed laser transmitting nodes or array modules are dynamically reorganized into multiple logically independent virtual transmitting sub-arrays. Each virtual sub-aperture serves the corresponding underwater target to be communicated with. Based on a preset identity mapping relationship, a unique orthogonal code sequence is matched to each communication link, and the bipolar orthogonal code sequence is mapped to a unipolar pulse control sequence adapted to the characteristics of the laser. Each virtual sub-aperture works collaboratively, firing concurrently at the water-air interface, forming multiple independent acoustic beams pointing towards different targets underwater. This application achieves flexible parallel transmission from multiple air platforms to multiple underwater users through a joint mechanism of spatial division multiplexing (SDMA) and code division multiplexing (CDMA), and effectively filters beam aliasing interference at the receiving end using orthogonal codes, significantly improving the system's concurrent capacity, anti-interference capability, and unidirectional link security.

[0021] Please see Figure 1 The first embodiment of this application provides a multi-user parallel laser-induced acoustic communication method based on array dynamic partitioning and orthogonal coding, comprising the following steps: S1: Obtain the real-time location coordinates, unique identifier, and communication requirements of the target to be communicated. Based on the real-time location coordinates and communication requirements, dynamically divide the laser emission array to obtain a virtual emission subarray that is oriented to serve the corresponding target to be communicated.

[0022] Obtain the designated water area The real-time location coordinates of each target to be communicated and its corresponding unique identifier are used to determine the communication requirements of each target based on the distance of each target to be communicated relative to the laser emitting array and the channel environment parameters.

[0023] based on The real-time location coordinates and communication requirements of the target to be communicated are used to dynamically divide the laser emitting array, which contains multiple laser emitting units, into... Each virtual transmitter subarray is logically independent. The size and orientation of each virtual transmitter subarray are configured so that each virtual transmitter subarray is directed to serve a corresponding target to be communicated with.

[0024] Specifically, based on the principle of non-uniform resource allocation, the laser emitting array containing multiple laser emitting units is dynamically divided into... The process of creating a virtual transmitter subarray is as follows: First, calculate the straight-line distance from each target to be communicated to the center of the laser emitting array. Set the number of laser emitting units contained in each virtual emitting subarray. distance from the line It is proportional to the square of, that is This ensures that the acoustic energy density projected onto a distant target compensates for transmission losses. Simultaneously, the total number of laser emitting units in all virtual emitting subarrays cannot exceed the total number of laser emitting units in the laser emitting array itself.

[0025] Among them, the Number of laser emitting units allocated to each virtual emitting subarray Based on the following formula, we get: ; In the formula, This represents the total number of units in the laser emitting array. For the first The straight-line distance from the target to be communicated to the center of the laser emitting array. The function represents rounding to the nearest integer. Its physical principle is that underwater sound wave propagation follows the spherical wave diffusion law, and the sound intensity attenuation is proportional to the square of the distance. By adjusting the emission aperture size and the number of laser emission units... and Proportional to the amplitude of the far-field received sound pressure level. Satisfy the following formula: ; By dynamically dividing the laser emission array, energy loss due to geometric transmission is compensated at the physical level, ensuring that the signal-to-noise ratio received from targets at different distances tends to a constant value. This is to ensure a balance in communication quality.

[0026] In an optional embodiment, the geometric center of the virtual transmitting subarray is selected, and a suitable area is selected on the physical plane or spatial distribution of the laser transmitting array by a search algorithm to minimize the scanning deflection angle of each virtual transmitting subarray to the corresponding target to be communicated. This area is used as the deployment area of ​​the virtual transmitting subarray to reduce the grid lobe interference and the decrease in sound source level caused by large-angle scanning.

[0027] Furthermore, when the azimuth difference between two or more targets is less than a preset threshold, resulting in overlapping areas in the physical space of their corresponding virtual emission subarrays, an array element reuse strategy can be adopted: the laser emission units located in the overlapping area are marked as reuse units to improve resource utilization.

[0028] S2: Based on the preset identity-code sequence mapping relationship, match the orthogonal code sequence corresponding to the unique identity identifier, use the orthogonal code sequence to spread spectrum modulate the user data stream to obtain the spread spectrum digital signal, and then map it to obtain a multi-channel pulse control sequence.

[0029] Based on a pre-defined identity-code sequence mapping, an orthogonal code sequence corresponding to the unique identifier of each target to be communicated is matched from the orthogonal spreading code set. In an optional embodiment, the orthogonal spreading code set is selected from one of the following: the Walsh-Hadamard code sequence set, the m-sequence preferred pair set, the Gold code sequence set, or the Kasami sequence set. The chip rate of the orthogonal code sequence is configured to be no higher than the effective acoustic bandwidth of the laser-induced acoustic signal to ensure that the spectral energy of the spread signal is concentrated in the frequency band with the highest photoacoustic conversion efficiency.

[0030] K independent user data streams are received. Each user data stream is spread-spectrum modulated using a uniquely matched orthogonal code sequence to obtain a spread-spectrum digital signal. This spread-spectrum digital signal is then mapped to a multi-channel pulse control sequence adapted to the unipolar emission characteristics of the laser. Optionally, the multi-channel pulse control sequence adapted to the unipolar emission characteristics of the laser can be generated using any one or a combination of the following modulation strategies: Strategy 1: PPM mapping, which maps each chip after orthogonal spread spectrum to the temporal position offset of the laser pulse within a fixed time window, and uses the relative position of the pulse to carry chip information.

[0031] Strategy 2: OOK mapping, which maps each chip after orthogonal spread spectrum to the "on" or "off" state of the laser pulse, where chip "1" drives the laser to emit a pulse, and chip "0" or "-1" drives the laser to remain silent.

[0032] The above strategy converts the bipolar orthogonal code characteristics into unipolar optical pulse characteristics that the laser can respond to. The receiver recovers the bipolar signal characteristics through DC removal processing or time-slot differential detection, thereby achieving orthogonal decoding.

[0033] In an optional embodiment, a direct sequence spread spectrum-pulse position modulation (DSSS-PPM) joint modulation method is employed to generate a multi-path pulse control sequence adapted to the unipolar emission characteristics of the laser. Specifically, for the spread spectrum... individual code chip The generated laser pulse waveform The description is as follows: ; In the formula, It is a rectangular pulse function. For chip cycle, The pulse width is defined here. This mapping converts the bipolar orthogonal code features into unipolar optical pulse position information, and the laser pulse waveforms corresponding to all code chips are spliced ​​together in time sequence to obtain a multi-channel pulse control sequence.

[0034] S3: Calculate the trigger time delay for each virtual transmitter subarray. Based on the multi-pulse control sequence and the trigger time delay, simultaneously drive the laser emitting units in each virtual transmitter subarray to emit laser pulses. The receiving end uses orthogonal code sequences for decoding and interference removal to achieve parallel communication.

[0035] For each virtual transmitting subarray, the trigger time delay of each laser emitting unit in the virtual transmitting subarray is independently calculated based on the real-time position coordinates of the corresponding target to be communicated, so as to achieve acoustic wavefront alignment for the target, form a more directional beam, and improve communication performance.

[0036] Regarding the first The first virtual transmitter subarray Each laser emitting unit calculates its trigger time delay by taking into account the propagation differences between air and water. The formula is: ; In the formula, The projection point of the laser emitting unit on the water surface to the first... The acoustic range of the target to be communicated. The speed of sound in water, The optical path length from the laser emitting unit to the projection point on the water surface is given. The speed of light in air. This is the reference time constant used for global beam synchronization.

[0037] Furthermore, based on the multi-pulse control sequence and the trigger time delay, the laser emitting units in each virtual emitting subarray are simultaneously driven to work together to emit laser pulses toward the water-air interface, forming K independent acoustic beams pointing toward different communication targets in parallel in the underwater medium, thus realizing the parallel excitation of multiple beams.

[0038] In an optional embodiment, the signal driving the multiplexing unit is generated by performing linear superposition or optical power combining operations in the time domain on the involved multi-channel pulse control sequences, so that the intensity of the laser pulses emitted by the multiplexing unit simultaneously carries information characteristics of multiple users. The emitted laser pulse sequence also includes periodically inserted synchronization pilot frames. The synchronization pilot frames consist of Barker Code or Linear Frequency Modulation (LFM) signals with strong autocorrelation characteristics, used to assist the receiver in establishing a demodulation time reference.

[0039] Specifically, the signal driving the multiplexing unit is generated by performing linear superposition or optical power combining operations in the time domain on the involved multi-pulse control sequences, as shown in the formula: ; In the formula, The signal that drives the multiplexing unit, The set of multiplexed pulse control sequences in which the multiplexing unit participates. For the index of the multi-channel pulse control sequence, For the first Waveform of the pulse control sequence. For time variables, For the first The trigger time delay corresponding to the path sequence.

[0040] In order to achieve linear superposition of signals, the laser emitting unit in this embodiment is configured as a power adjustable laser, or a dense array unit composed of multiple micro lasers is used, so that the intensity of the emitted laser pulse can respond to the superposition value of multiple user data (such as intensity 0, 1, 2...), thereby exciting a sound pressure signal with corresponding amplitude underwater.

[0041] Since laser amplification is achieved through thermal energy injection, the linear superposition of optical power will be transformed into the linear superposition of sound pressure amplitude. This allows the multiplexing unit to carry the information characteristics of multiple users while transmitting energy. The receiving end can recover the data of each user through demultiplexing, thereby improving the accuracy of transmission.

[0042] At the locations of each target to be communicated, the receiver uses a locally pre-stored orthogonal code sequence bound to its own identifier to perform cross-correlation on the received mixed acoustic signal. The corresponding user data stream is extracted using the autocorrelation peak characteristics of the orthogonal code sequence, and the spatial overlap interference from other virtual transmitter subarrays is filtered out using the cross-correlation orthogonality characteristics, thus achieving orthogonal decoding and interference removal.

[0043] Specifically, the system processing gain that can be obtained from the orthogonal decoding and interference removal process. From the spreading code length The theoretical gain value is determined to be: ; Even under the worst-case scenario of complete beam overlap, if the spreading code length With a signal-to-interference ratio (SIR) of 64, the system can still provide an improvement of about 18 dB, thereby effectively suppressing multiple access interference from adjacent beams.

[0044] Please see Figure 2The second embodiment of this application provides a multi-user parallel laser acoustic communication device based on array dynamic partitioning and orthogonal coding, including an airborne transmitter and an underwater receiver.

[0045] The airborne transmitter is configured to be mounted on one or more drones working in coordination. Each drone includes a main control unit, a situational awareness module, a collaborative communication module, a drive circuit, a pulsed laser, and a beam projection device.

[0046] The input terminal of the main control unit is connected to the situational awareness module and the cooperative communication module to obtain the real-time position coordinates, unique identification and communication requirements of the target to be communicated. Based on the real-time position coordinates and communication requirements, the laser emission array is dynamically divided to obtain a virtual emission subarray that is oriented to serve the corresponding target to be communicated.

[0047] The main control unit is connected to the pulsed laser through a drive circuit. It is used to match the orthogonal code sequence corresponding to the unique identity based on the preset identity-code sequence mapping relationship, and use the orthogonal code sequence to spread spectrum modulate the user data stream to obtain the spread digital signal. The spread signal is then mapped to obtain a multi-channel pulse control sequence. The trigger time delay corresponding to each virtual transmitter subarray is calculated. Based on the multi-channel pulse control sequence and the trigger time delay, the pulsed laser is driven to control the beam projection device to simultaneously drive the laser emission unit in each virtual transmitter subarray to emit laser pulses.

[0048] Furthermore, the beam projection device adopts a modular splicing structure or a distributed networking structure.

[0049] When a modular splicing structure is adopted, each module contains several laser emitting units and their corresponding driving circuits, and receives the home configuration command through a high-speed bus.

[0050] When a distributed networking structure is adopted, the laser emitting units are distributed on multiple collaborative aerial flight platforms. The array beam controller dynamically calls the emitting resources on each platform through a wireless self-organizing network link and logically maps them into components of a virtual emitting subarray.

[0051] Both the pulsed laser and the underwater receiver are equipped with a time-synchronized codebook update mechanism. Based on a preset timetable or a unified pseudo-random algorithm seed, the two parties synchronously switch the currently used orthogonal spreading code set at a predetermined time to prevent a single code sequence from being intercepted and deciphered, thus ensuring the security of the one-way communication link.

[0052] The underwater receiver includes a signal processing terminal, an analog-to-digital converter, an analog front-end, and an underwater transducer.

[0053] The underwater transducer is connected to a signal processing terminal via an analog front-end and an analog-to-digital converter (ADC). The underwater transducer receives acoustic signals generated by laser pulse excitation, while the signal processing terminal uses orthogonal code sequences to decode and remove interference from the digital signals converted by the ADC, enabling parallel communication. The ADC converts the acoustic signals into digital signals.

[0054] Specifically, the signal processing terminal locally stores an orthogonal code despreading key that is bound to the unique identifier of the target to be communicated.

[0055] Example 1: Multi-user parallel laser-induced acoustic communication instance.

[0056] A distributed aerial swarm consisting of 10 drones working in coordination is set up as the aerial transmitter to conduct cross-media collaborative parallel communication with two targets at the underwater receiver.

[0057] Configure system parameters: Airborne transmitter (distributed airborne cluster): Deployed with 10 micro-UAVs (numbered UAV1 to UAV10), forming a sparsely distributed laser emission array. Each UAV carries a high-energy pulsed laser with a wavelength of 1064nm (single-point emission source). The entire cluster has 10 independent laser emission units, which are logically considered as a complete reconfigurable array aperture. The cluster flies at an altitude of 150m, and the nodes maintain nanosecond-level time synchronization via UWB ranging links.

[0058] The aerial launch node (UAV) utilizes a quadcopter platform and is equipped with a semiconductor-pumped solid-state laser (wavelength 1064nm, pulse width 10ns). The node integrates a UWB positioning and communication module for maintaining relative position awareness (accuracy <10cm) and time synchronization (accuracy <10ns) with other nodes. The built-in FPGA controller receives virtual array partitioning instructions from the master node and calculates the transmission delay and drives the laser based on its logical affiliation (which target it serves) and the spreading code table.

[0059] Underwater receiver (underwater multi-target): Target A: Located in deep water, coordinates (0,0,-800m), with long communication distance, requiring high sound source level.

[0060] Target B: Located in shallow water, coordinates (200, 100, -50m), with short communication distance.

[0061] Encoding parameters: The system uses a 128-order Walsh-Hadamard orthogonal spreading code set.

[0062] Each target in the underwater receiver is equipped with a broadband omnidirectional hydrophone (response band 20kHz-100kHz). The internal signal processing board (DSP) has a Walsh code sequence bound to the target ID. The DSP runs a parallel correlator algorithm, which can extract its own spread spectrum peak from the low signal-to-noise ratio aliased signal.

[0063] Both the air-to-air transmitter and the underwater receiver are equipped with high-precision atomic clocks and have pre-set daily codebook transition rules based on GPS time. Every 24 hours, both parties synchronously change to a new spreading code mapping table to prevent feature leakage caused by using the same code for an extended period.

[0064] S1: The distributed air cluster master control unit obtains the three-dimensional coordinates of target A and target B, and determines the communication quality requirements based on the distance and channel parameters: Target A, due to its long distance and large attenuation, requires at least 80% of the array energy for synthesis; Target B only requires 20% of the energy.

[0065] Based on the principle of non-uniform resource allocation, the system dynamically divides the physical resources of 10 UAVs into two logically independent virtual launch subarrays: The first virtual transmission subarray, consisting of eight UAVs (UAV1-UAV8), is dedicated to serving target A. These eight distributed nodes logically constitute a large-aperture deep-sea communication array.

[0066] The second virtual transmission subarray, consisting of two UAV9 and UAV10 aircraft, is dedicated to serving target B.

[0067] S2: The system assigns orthogonal codes according to the preset identity-code sequence mapping table: target A matches Walsh sequence CA; target B matches Walsh sequence CB; CA and CB satisfy the orthogonality condition.

[0068] Link A: After the user data DA is spread by CA and mapped by DSSS-PPM, pulse control commands are generated and distributed to the first virtual transmitter subarray (UAV1-UAV8).

[0069] Link B: After the user data DB is spread and mapped by CB, pulse control commands are generated and distributed to the second virtual transmitter subarray (UAV9-UAV10).

[0070] S3: Each UAV node independently calculates the true time delay across the medium. In an optional embodiment, for target A, although UAV1 and UAV8 are in different spatial locations, by calculating their respective propagation time to target A (i.e., the sum of optical path and acoustic path) and calculating the triggering time in reverse based on the global synchronization reference time (i.e., the farther the distance, the earlier the triggering), it is ensured that the sound waves excited by the two are wavefront aligned (coherently superimposed) at a depth of 800m.

[0071] Next, triggered by a global synchronization clock, the virtual subarrays work in concert: UAV1-UAV8 simultaneously emit laser pulse clusters carrying CA characteristics toward target A; UAV9-UAV10 simultaneously emit laser pulse clusters carrying CB characteristics toward target B. In the underwater medium, this forms two independent acoustic beams with different directions and focused energy.

[0072] At target A: A strong synthesized signal was received from 8 drones, and the data DA was successfully demodulated using the local CA code.

[0073] At target B: Located in shallow water, although it is affected by sidelobe interference from UAV1-UAV8, the cross-correlation value of the interference signal is zero when using the local CB code for correlation detection. Target B successfully filters out the interference and demodulates the data DB.

[0074] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the corresponding application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each corresponding application, but such implementation should not be considered beyond the scope of this application.

[0075] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A multi-user parallel laser-induced acoustic communication method based on array dynamic partitioning and orthogonal coding, characterized in that, Includes the following steps: The real-time location coordinates, unique identifier, and communication requirements of the target to be communicated are obtained. Based on the real-time location coordinates and the communication requirements, the laser emission array is dynamically divided to obtain a virtual emission subarray that provides directional service to the target to be communicated. Based on the preset identity-code sequence mapping relationship, the orthogonal code sequence corresponding to the unique identity is matched, and the user data stream is spread spectrum modulated using the orthogonal code sequence to obtain the spread spectrum digital signal, which is then mapped to obtain a multi-channel pulse control sequence. The trigger time delay corresponding to each of the virtual transmitting subarrays is calculated. Based on the multi-path pulse control sequence and the trigger time delay, the laser emitting units in each of the virtual transmitting subarrays are simultaneously driven to emit laser pulses. The receiving end uses the orthogonal code sequence for decoding and interference removal to achieve parallel communication.

2. The multi-user parallel laser-induced acoustic communication method based on array dynamic partitioning and orthogonal coding as described in claim 1, characterized in that, The dynamic partitioning process includes: calculating the straight-line distance from the target to be communicated to the center of the laser emitting array; based on the principle of non-uniform resource allocation, allocating and determining the number of laser emitting units in the virtual emitting subarray according to the square of the straight-line distance from each target to be communicated to the center of the laser emitting array; and dynamically partitioning the laser emitting array to obtain virtual emitting subarrays that are oriented to serve the corresponding target to be communicated.

3. The multi-user parallel laser-induced acoustic communication method based on array dynamic partitioning and orthogonal coding as described in claim 1, characterized in that, The multi-channel pulse control sequence is obtained by splicing the laser pulse waveforms corresponding to all the code chips in chronological order. The formula for obtaining the laser pulse waveform is: ； In the formula, For the first individual code chip The laser pulse waveform, It is a rectangular pulse function. For chip cycle, This represents the pulse width.

4. The multi-user parallel laser-induced acoustic communication method based on array dynamic partitioning and orthogonal coding as described in claim 1, characterized in that, The process of calculating the trigger time delay corresponding to each virtual transmitting subarray includes: for each virtual transmitting subarray, based on the real-time position coordinates of the target to be communicated, calculating the trigger time delay of each laser emitting unit within the virtual transmitting subarray, using the following formula: ； In the formula, For the trigger time delay amount, The projection point of the laser emitting unit on the water surface to the first The acoustic range of the target to be communicated. The speed of sound in water, The optical path length from the laser emitting unit to the projection point on the water surface is given. The speed of light in air. This is the reference time constant used for global beam synchronization.

5. The multi-user parallel laser-induced acoustic communication method based on array dynamic partitioning and orthogonal coding as described in claim 2, characterized in that, The formula for determining the number of laser emitting units in the virtual emitting subarray is: ； In the formula, The number of laser emitting units, This represents the total number of units in the laser emitting array. For the first The straight-line distance from the target to be communicated to the center of the laser emitting array. This represents the rounding function.

6. The multi-user parallel laser-induced acoustic communication method based on array dynamic partitioning and orthogonal coding as described in claim 2, characterized in that, The geometric center of the virtual transmitter subarray is selected as the deployment area of ​​the virtual transmitter subarray to reduce signal interference; The process of calculating the geometric center of the virtual transmitting subarray includes: on the physical plane or spatial distribution of the laser transmitting array, selecting the region that minimizes the scanning deflection angle of each virtual transmitting subarray to the corresponding target to be communicated on the search algorithm, thereby obtaining the geometric center of the virtual transmitting subarray.

7. The multi-user parallel laser-induced acoustic communication method based on array dynamic partitioning and orthogonal coding as described in claim 1, characterized in that, The decoding and interference removal process includes: performing cross-correlation calculations on the received signal at the receiving end using the orthogonal code sequence to filter out spatial overlap interference.

8. The multi-user parallel laser-induced acoustic communication method based on array dynamic partitioning and orthogonal coding as described in claim 1, characterized in that, When the virtual emission subarrays have overlapping areas in physical space, an array element reuse strategy is adopted to mark the laser emission units located in the overlapping areas as reused units, thereby improving resource utilization.

9. The multi-user parallel laser-induced acoustic communication method based on array dynamic partitioning and orthogonal coding as described in claim 8, characterized in that, The signal driving the multiplexing unit is generated by performing linear superposition or optical power synthesis operations in the time domain on the multi-channel pulse control sequence involved, so that the multiplexing unit carries the information characteristics of multiple users while emitting laser pulse intensity.

10. A multi-user parallel laser-acoustic communication device based on array dynamic partitioning and orthogonal coding, applied to the multi-user parallel laser-acoustic communication method based on array dynamic partitioning and orthogonal coding as described in any one of claims 1-9, characterized in that, include: Airborne transmitter and underwater receiver; The airborne transmitter includes several UAVs, each of which includes a main control unit, a situational awareness module, a cooperative communication module, a drive circuit, a pulsed laser, and a beam projection device. The input terminal of the main control unit is connected to the situational awareness module and the cooperative communication module, and is used to obtain the real-time position coordinates, unique identification and communication requirements of the target to be communicated. Based on the real-time position coordinates and the communication requirements, the laser emission array is dynamically divided to obtain a virtual emission subarray that is oriented to serve the corresponding target to be communicated. The main control unit is connected to the pulsed laser through the driving circuit. It is used to match the orthogonal code sequence corresponding to the unique identity based on the preset identity-code sequence mapping relationship, and use the orthogonal code sequence to spread spectrum modulate the user data stream to obtain the spread spectrum digital signal. The spread signal is then mapped to obtain a multi-channel pulse control sequence. Calculate the trigger time delay for each of the virtual emission subarrays, and based on the multi-path pulse control sequence and the trigger time delay, drive the pulsed laser to control the beam projection device to simultaneously drive the laser emission units in each of the virtual emission subarrays to emit laser pulses; The underwater receiver includes a signal processing terminal, an analog-to-digital converter, an analog front-end, and an underwater transducer; The underwater transducer is connected to the signal processing terminal via the analog front-end and the analog-to-digital converter; the underwater transducer is used to receive the acoustic signal generated by the laser pulse, and the signal processing terminal is used to decode and remove interference from the digital signal converted by the analog-to-digital converter using the orthogonal code sequence to achieve parallel communication.

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