Offshore long distance signal transmission method based on optical fiber signal distribution and shipborne relay

Abstract

The present application relates to the technical field of radio transmission, and discloses an offshore long-distance signal transmission method based on optical fiber signal distribution and shipborne relay, comprising the following steps: an optical fiber backbone node establishes an evaporation duct layer profile based on sea surface meteorological parameters and determines a transmission elevation angle, and uses an optical control reconfigurable intelligent surface to modulate an optical signal into a radio frequency beam and injects the radio frequency beam into the evaporation duct layer; a relay ship receives a signal, predicts absolute Euler angles based on a ship body hydrodynamics prediction model, calculates a feedforward compensation phase matrix to reconfigure a conformal reconfigurable intelligent surface phase, and realizes beam steady-state control to a target node; when a line-of-sight fails, the relay ship acquires a three-dimensional elevation distribution function of a target wake, searches for an optimal scattering cross section conforming to the law of reflection and recalculates a phase matrix, and realizes physical layer diffraction transmission. The present application uses pure electronic feedforward to offset the deviation caused by sea wave heaving, converts a dynamic wake into a passive relay reflection surface, and effectively improves the anti-shielding stability of a link under complex sea conditions.

Description

Technical Field

[0001] This invention relates to the field of radio transmission technology, specifically to a method for long-distance near-shore signal transmission based on fiber optic signal distribution and shipborne relay. Background Technology

[0002] Communication in nearshore and offshore areas typically relies on a combination of shore-based fiber optic networks and maritime wireless relay nodes. To overcome the limitations of the Earth's curvature and achieve beyond-line-of-sight transmission, current technologies often utilize marine evaporative waveguides as electromagnetic wave transmission channels.

[0003] At shore-based transmitters, traditional radio frequency (RF) systems often employ a multi-conversion and amplification architecture from digital baseband to radio frequency, resulting in complex hardware structures. When injecting signals into the waveguide layer, if there is a lack of a control mechanism for the transmission elevation angle, the RF signal can easily escape the total reflection condition and dissipate into free space, leading to low signal coupling within the waveguide layer and affecting overall transmission efficiency.

[0004] After the radio frequency signal reaches the relay ship at sea, it needs to be relayed to the target node in the open ocean via the relay antenna. When the relay ship operates on the sea surface, it is affected by hydrodynamics, and the hull will undergo attitude changes such as roll, pitch, and yaw. Currently, shipborne antennas mainly use mechanical servo gimbals for attitude compensation and beam alignment. The mechanical structure itself has a physical response delay. In the swell environment of the sea surface, the attitude adjustment of the mechanical gimbal lags behind the actual deflection of the hull, causing the radio frequency beam to be unable to stably point to the target receiver, resulting in a degraded communication link quality.

[0005] Furthermore, relay ships rely on line-of-sight conditions to transmit signals to distant target nodes. In actual maritime operations, communication links can be blocked by islands, reefs, or large vessels. When physical obstruction occurs, radio frequency signals that rely on line-of-sight propagation cannot reach the receiver, causing the line-of-sight link to fail. Existing communication systems struggle to maintain physical layer relay transmission under non-line-of-sight conditions. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a method for long-distance signal transmission in near-shore waters based on fiber optic signal distribution and shipborne relay, which solves the technical problems of beam pointing inaccuracy under wave disturbance and signal transmission interruption caused by physical obstruction of line-of-sight links in existing near-shore relay communication.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a near-shore long-distance signal transmission method based on fiber optic signal distribution and shipborne relay, applied to a near-shore communication system including fiber optic backbone nodes and relay vessels, comprising the following steps: Based on the sea surface meteorological environment parameters collected by the fiber optic backbone node, a corrected refractive index profile of the evaporation waveguide layer is established and the transmission elevation angle is determined. The fiber optic backbone node generates an optical signal carrying communication data. The optical signal is modulated into a radio frequency signal and injected into the marine evaporation waveguide layer using the optically controllable reconfigurable smart surface at the fiber optic backbone node. The relay ship receives the radio frequency signal, predicts the absolute Euler angle of the ship at the target time based on the preset ship hydrodynamic prediction model, calculates the feedforward compensation phase matrix to reconstruct the phase of the conformal reconfigurable smart surface on the relay ship, and realizes steady-state control of beam pointing towards the target node in the open sea. When the line-of-sight link between the relay ship and the offshore target node fails, the relay ship obtains the three-dimensional elevation distribution function of the wake of the offshore target node, searches for the optimal scattering cross section that conforms to the three-dimensional vector reflection law, and recalculates the feedforward compensation phase matrix based on the direction of the optimal scattering cross section to adjust the direction of the radio frequency beam and realize physical layer diffraction scattering transmission to the offshore target node.

[0008] Furthermore, regarding the mechanism for determining the transmission elevation angle, this invention extracts the minimum value of the modified refractive index profile function within the vertical space of the evaporating waveguide layer and determines it as the minimum modified refractive index within the waveguide layer. Based on this minimum modified refractive index and the modified refractive index at the height of the fiber optic backbone node antenna, the critical transmission elevation angle required to completely confine the radio frequency energy within the waveguide layer is calculated. The system strictly limits the actual transmission elevation angle within this critical transmission elevation angle, thereby cutting off the physical path for the radio frequency wave to escape into free space, and enabling the signal energy to be efficiently confined within the waveguide channel close to the sea surface, resulting in continuous total reflection.

[0009] The critical elevation angle of the launch The constraints satisfy the following relationship:

[0010] In the formula, and These represent the corrected refractive index at the height of the fiber backbone node antenna and the minimum corrected refractive index within the waveguide layer, respectively.

[0011] Furthermore, regarding the cross-domain modulation principle of optical signals to radio frequency signals, the method of modulating optical signals into radio frequency signals using a light-controlled reconfigurable smart surface includes: expanding the optical signal beam and incident it onto the back side of the light-controlled reconfigurable smart surface, exciting photogenerated carriers based on the internal photoelectric effect, and dynamically changing the bias voltage and equivalent junction capacitance of the photosensitive varactor diode on the back side according to the spatiotemporal distribution of the optical signal; simultaneously, the radio frequency microwave local oscillator signal is incident onto the front side of the light-controlled reconfigurable smart surface, and utilizing the equivalent resonant impedance shift caused by the dynamic change of the back side junction capacitance, the amplitude and phase of the complex reflection coefficient on the front side are simultaneously modulated by the light intensity to generate a radiated radio frequency field with a specific spatial angle distribution and data envelope.

[0012] Furthermore, regarding the steady-state control mechanism for the relay ship's beam pointing, the prediction of absolute Euler angles and calculation of the feedforward compensation phase matrix include: acquiring the system's inherent delay by synchronously inputting the three-dimensional linear acceleration vector, three-dimensional angular velocity vector, and inherent delay of the relay ship at the current moment, acquired through the inertial measurement unit, into the ship's hydrodynamic prediction model; overcoming the system's inherent time lag, predicting the ship's roll angle, pitch angle, and yaw angle corresponding to the target moment after superimposing the inherent delay through forward time-series integration, and constructing a rotation transformation matrix from the absolute geographic coordinate system to the local coordinate system accordingly. Subsequently, acquiring the position vector, incident wave vector direction vector, and initial target wave vector vector of the conformal reconfigurable intelligent surface physical reflection unit; combining the inverse matrix of the rotation transformation matrix, mapping the wave vector in absolute space to the local relative space after the ship's deflection, and constructing the feedforward compensation phase matrix by calculating the discrete phase shift values ​​required for each physical reflection unit. The feedforward compensation phase of each physical reflection unit... The calculation is based on the generalized Snell's law as follows:

[0013] In the formula, It is the inverse of the rotation transformation matrix. Let the initial target wave vector be... Let be the direction vector of the incident wave vector. This is the position vector of the physical reflection unit.

[0014] Furthermore, regarding the wake diffraction and scattering mechanism when the line-of-sight link fails, after obtaining the three-dimensional elevation distribution function of the wake of the offshore target node, the partial derivatives of the elevation distribution function in the directions of the two orthogonal coordinate axes in the horizontal plane are calculated to obtain the elevation change gradient. Based on this, a local normal vector field accurately characterizing the instantaneous three-dimensional geometric curvature of the dynamic water surface is constructed. The desired reflection wave vector is constructed by back-calculating the coordinates of the receiving antenna of the offshore target node and the candidate reflection points of the wake. The theoretical reflection wave vector is derived by forward-calculating the incident wave vector of the relay ship to the wake surface and the local normal vector field. The system traverses and searches within the effective wake divergence angle region constrained by the three-dimensional elevation distribution function, calculates the three-dimensional vector residual between the desired reflection wave vector and the theoretical reflection wave vector, and determines the region that minimizes this vector residual as the optimal scattering cross section. The system uses the three-dimensional direction vector of the optimal scattering cross section to replace the initial target wave vector vector, restarts the underlying solution of the compensation matrix, and controls the radio frequency beam to accurately illuminate the wake surface with a specific geometric configuration to cause secondary directional scattering.

[0015] Furthermore, regarding multipath processing and global closed-loop control at the offshore receiver, after transmission via physical layer diffraction and scattering, multipath dispersion caused by non-uniform undulations on the wake surface occurs. At the offshore target node, the radio frequency signal undergoes a maximum ratio combining mechanism based on channel fading complex coefficient conjugate matching using a multi-antenna receiving array, forcing the scattered multipath components to undergo in-phase amplitude superposition and baseband demodulation. Simultaneously, the offshore target node measures the instantaneous signal-to-noise ratio and delay spread of the equivalent baseband signal in real time, generating a link receiving status feedback frame, which is then transmitted back to the fiber backbone node via an independent reverse control channel link. The fiber backbone node triggers reverse calibration based on the attenuation trend, dynamically shrinking the radio frequency beam and enhancing waveguide coupling density by adjusting the output transmit elevation angle, and driving the relay ship to synchronously correct the target wave vector update compensation matrix, completing the full-link adaptive closed-loop iteration covering the transmitter, relay, and receiver.

[0016] Furthermore, regarding the underlying physical reflection architecture, both the optically reconfigurable smart surface and the conformal reconfigurable smart surface are composed of multiple subwavelength physical reflection units arranged in an array to support high-degree-of-freedom reconfiguration of spatial beams.

[0017] This invention provides a method for long-distance signal transmission in near-shore waters based on fiber optic signal distribution and shipborne relay. It has the following beneficial effects: 1. This invention utilizes a light-controlled reconfigurable smart surface to directly map optical signals into radio frequency (RF) beams and precisely inject them into the marine evaporation waveguide layer. This mechanism avoids the use of traditional digital frequency conversion RF links, simplifying the shore-based hardware architecture. Simultaneously, by combining meteorological profiles to limit the transmission elevation angle within the total internal reflection critical value, it effectively blocks the path of electromagnetic energy dissipation into free space. This results in the RF signal being densely confined within a low-loss physical channel close to the sea surface, effectively reducing attenuation loss in near-shore, over-the-horizon, high-bandwidth transmission.

[0018] 2. To address the issue of beam deviation caused by ship rolling in complex sea conditions, this invention introduces a ship hydrodynamic prediction model. The system overcomes transmission delays, predicts the absolute Euler angles at the target moment in advance, and calculates the inverse rotation matrix accordingly, directly driving the conformal intelligent surface of the relay ship to perform array phase compensation. This purely electronic feedforward control overcomes the physical lag limitations of mechanical servo gimbals, ensuring stable radio frequency beam coverage of distant targets with extremely high real-time performance even in turbulent sea environments.

[0019] 3. To address line-of-sight link disruptions caused by physical obstruction, this invention utilizes the dynamic wake generated by ship navigation as a passive electromagnetic relay reflector surface. The system constructs a microscopic normal vector field of the water surface by extracting the three-dimensional elevation distribution of the wake, and determines the optimal scattering cross section based on the three-dimensional vector reflection law. Subsequently, the phase of the intelligent surface array is reconfigured, guiding the beam to be projected onto the water area to induce secondary directional scattering. This cross-domain reconstruction mechanism constructs an effective physical layer diffraction relay channel under non-line-of-sight conditions, improving the communication system's anti-obstruction capability. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall application scenario of the near-shore long-distance signal transmission system of the present invention; Figure 2 This is a schematic diagram of the method flow of the present invention; Figure 3 This is a schematic diagram of the stacked structure of the reconfigurable smart surface physical reflection unit of the present invention; Figure 4 This is a schematic diagram illustrating the direct optical-RF mapping and modulation principle of the optically reconfigurable smart surface of the present invention. Figure 5 This is a geometric model and vector diagram of the non-line-of-sight wake diffraction scattering of the present invention; Figure 6 This is a block diagram of the system feedforward compensation and closed-loop feedback control module of the present invention. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Please see the appendix Figure 1 -Appendix Figure 6 This invention provides a method for long-distance signal transmission in near-shore waters based on fiber optic signal distribution and shipborne relay. This method is suitable for near-shore communication systems equipped with fiber optic backbone nodes and relay vessels. The entire communication system is built between high-capacity fiber optic infrastructure and the vast marine environment, establishing a layered physical transmission link extending from the shore to the deep sea, enabling stable radio frequency beam coverage for various target nodes in the open ocean.

[0023] The fiber optic backbone nodes are equipped with optically reconfigurable smart surfaces, while the relay ship carries conformal reconfigurable smart surfaces. Both types of smart surfaces consist of a large number of subwavelength physical reflection units arranged in an array. Both types of smart surfaces use a rectangular grid array arrangement with a unit spacing of 0.4 times the operating wavelength, which is subwavelength scale. Each physical reflection unit is a square patch structure. The top metal patch is made of copper, with a thickness of 0.035 mm and a side length of 0.3 times the operating wavelength. The intermediate dielectric layer uses Rogers RO4350B substrate with a dielectric constant of 3.48 and a thickness of 0.508 mm. The bottom layer is a fully covered copper ground plane. The optical fiber backbone node's optically reconfigurable smart surface integrates a photosensitive control network on its backplane. This network uses incident light signals to trigger photosensitive varactor diodes, generating a junction capacitance change and a bias voltage field to regulate the electromagnetic boundary conditions on the smart surface's front side. The conformal reconfigurable smart surface mounted on the relay ship utilizes a flexible polyimide substrate, manufactured through a curved surface lamination process. Its array curvature precisely matches the fluid streamline shape of the relay ship's hull (the deviation between the array curvature and the hull curvature does not exceed 5%), mitigating the adverse effects of additional aerodynamic and hydrodynamic drag. The position vectors of each subwavelength physical reflection unit... Before leaving the factory, the coordinates are calibrated using 3D laser scanning with an accuracy better than 0.1mm. The data is then directly stored in the shipboard control unit and incorporated into the feedforward compensation phase calculation process without the need for additional surface-to-plane projection correction. Besides the varactor diode control scheme, the reconfigurable smart surface of this invention can also achieve phase reconstruction using PIN diode switching control, MEMS microstructure control, and other methods.

[0024] The size of this smart surface array is set in three-dimensional space as follows: The first physical reflection unit is defined with its local coordinate origin located at the array's geometric center. The second unit... line, number The position vector of the subwavelength physical reflection unit of the column in the local coordinate system of the smart surface is expressed as: This position vector independently records the three-dimensional spatial coordinate characteristics of each reflecting unit, providing hardware position constraints for subsequent phase calculation of spatial beam pointing.

[0025] The near-shore long-distance signal transmission method based on fiber optic signal distribution and shipborne relay may include the following steps: Based on the sea surface meteorological environment parameters collected by the fiber backbone node, a corrected refractive index profile of the evaporation waveguide layer is established and the transmission elevation angle is determined. The fiber backbone node generates an optical signal carrying communication data. The optical signal is modulated into a radio frequency signal and injected into the marine evaporation waveguide layer using the optically reconfigurable smart surface at the fiber backbone node. The relay ship receives the radio frequency signal, predicts the absolute Euler angle of the ship at the target time based on the preset ship hydrodynamic prediction model, calculates the feedforward compensation phase matrix to reconstruct the phase of the conformal reconfigurable smart surface, and realizes steady-state control of beam pointing towards the target node in the open sea. When the line-of-sight link between the relay ship and the offshore target node fails, the relay ship obtains the three-dimensional elevation distribution function of the wake of the offshore target node, searches for the optimal scattering cross section that conforms to the three-dimensional vector reflection law, and recalculates the feedforward compensation phase matrix based on the direction of the optimal scattering cross section to adjust the direction of the radio frequency beam and realize physical layer diffraction scattering transmission to the offshore target node.

[0026] When implementing the above method, the fiber optic backbone node acts as the signal generation source, continuously acquiring real-time meteorological data of the air-sea boundary layer and deducing the nonlinear relationship between atmospheric refractive index and altitude. Because sea surface evaporation creates a low-loss physical channel similar to a waveguide at a certain height close to the sea surface, the system transmits the radio frequency signal beyond line-of-sight using this waveguide layer as a carrier. After the radio frequency beam is transmitted to and received by the relay ship in the sea area where it is located, the relay ship's spatial attitude is constantly in a nonlinear deflection state due to dynamic disturbances such as wave heave and roll.

[0027] To maintain the line-of-sight link under dynamic disturbances, the edge computing units of the relay ship extract the initial incident wave vector incident on the relay ship. And set the initial target wave vector pointing to the target node in the far sea. The relay ship's built-in hydrodynamic prediction model outputs rotational transformation results based on the ship's motion parameters, driving the conformal reconfigurable smart surface to generate a feedforward compensation phase matrix that adapts to it. The matrix It contains discrete phase shift values ​​corresponding to each subwavelength physical reflection unit in the array. By changing the phase shift value By applying the reflection coefficient to the corresponding physical unit, the system establishes an electromagnetic phase compensation mechanism to counteract the mechanical deflection of the hull.

[0028] During the normal communication cycle, the RF beam, after compensation, directly illuminates the offshore target node. The link monitoring module of the offshore target node continuously detects the received signal status at a period of 10ms and transmits the detection results back to the relay ship in real time via the reverse control channel. The relay ship determines the link status based on the transmitted data—during the system initialization phase, under unobstructed line-of-sight conditions, the received signal power is continuously counted over 10 seconds, and the average value is taken as the reference power for stable line-of-sight transmission. At the same time, the multipath delay spread value during this period is counted (calculated using the root mean square delay spread of the power delay distribution), and its time domain standard deviation is calculated as the standard deviation of the stable delay. The preset received signal strength threshold is the value after the reference power is attenuated by 10dB, and the preset multipath delay mutation threshold is twice the standard deviation of the stable delay. When the received signal strength is lower than the strength threshold for three consecutive detection cycles, or the delay spread value exceeds the mutation threshold in a single cycle, it is determined that the line-of-sight link has failed due to physical obstruction, and the wake scattering transmission mode (i.e., the abnormal handling transmission strategy in non-line-of-sight environments) is immediately triggered.

[0029] The distant target node disrupts the static equilibrium of the sea surface during its navigation, generating a dynamic wake with significant topological undulations behind it. The system models the geometric surface of this wake region as a three-dimensional elevation distribution function. Among them, parameters and parameters The function value represents two orthogonal spatial coordinates within the projection plane of the horizontal sea surface. This represents the vertical elevation undulation of the water surface at that coordinate. The relay vessel uses this elevation distribution function to extract the local three-dimensional tilt characteristics of the sea surface and calculates the optimal scattering cross section that meets the electromagnetic wave reflection conditions. The system abandons the original direct beam pointing and, based on the recalculated feedforward compensation phase matrix, precisely projects the beam onto the optimal scattering cross section. It utilizes the secondary scattering effect of the water surface to overcome physical barriers and construct a physical-level redirection relay transmission link.

[0030] In this embodiment, the steps for establishing the transmission boundary and cross-frequency band signal modulation are specifically described, focusing on the signal transmission and waveguide layer injection mechanism at the fiber optic backbone node. The system performs real-time modeling and adaptive matching of the electromagnetic physical characteristics of the air-sea boundary layer, aiming to maximize channel capacity and reduce transmission loss.

[0031] The meteorological sensing module of the fiber optic backbone node continuously collects sea surface meteorological environmental parameters in the operational sea area, including sea surface temperature, atmospheric pressure, relative humidity distribution, and wind speed at a height of 10m above the sea surface. Based on the turbulent exchange mechanism of the air-sea boundary layer, the above meteorological data is input into the Moning-Obukhov similarity theory model, combined with preset sea surface aerodynamic roughness parameters. Calculations show that the effect of altitude varies. (Unit: m) Nonlinearly varying modified refractive index profile function of evaporating waveguide layer (Unit: M units), its analytical form is:

[0032] In the formula, This is the initial corrected refractive index at sea level, calculated from standard atmospheric parameters; The aerodynamic roughness parameters for the corresponding sea surface are empirical parameters, with values ​​ranging from 0.0001m to 0.01m for nearshore areas. These values ​​can be selected from a table based on sea state levels; the fitting coefficients... , Based on the derivation of the logarithmic linear profile model under near-surface neutral atmospheric conditions, the mathematical model calculation logic is as follows:

[0033]

[0034] in, This is a typical engineering approximation of the corrected vertical refractive index gradient under neutral atmospheric conditions, with units of M units / m. Under non-neutral stratification conditions, the gradient can be corrected based on the Moning-Obukhov length, and the correction method follows the general profile function of the Moning-Obukhov similarity theory. The evaporation waveguide height (unit: m) is determined by sea surface temperature, atmospheric temperature at 10m above sea level, atmospheric pressure, relative humidity, and frictional wind speed at 10m. It was obtained through iterative solution using the COARE 3.0 block flux algorithm.

[0035] To ensure that the radio frequency beam can be effectively captured by the marine evaporating waveguide layer, the data processing unit of the fiber optic backbone node needs to solve for the extreme physical quantities within this waveguide layer. This is achieved by analyzing the profile function. Along height The extreme values ​​of the directional calculations are used to obtain the waveguide height corresponding to the minimum corrected refractive index. The minimum value of this profile function in the vertical space of the waveguide layer is then extracted and determined as the minimum corrected refractive index. .

[0036] The absolute altitude of the transmitting antenna of the fiber optic backbone node is simultaneously calibrated as follows: Substituting this height parameter into the aforementioned corrected refractive index profile function, the corrected refractive index at the height of the fiber optic backbone node antenna is calculated. .

[0037] Based on the ray tracing equation for electromagnetic waves in non-uniform atmospheric media and Snell's law, the system calculates the critical elevation angle required to completely confine radio frequency energy within the waveguide layer. The critical elevation angle characterizes the critical condition for continuous total internal reflection of the electromagnetic beam within the waveguide layer, and its mathematical expression is defined as:

[0038] In the formula and All units are in megohms (M). The calculated critical elevation angle can be converted to angles by multiplying by 180 / π. The actual transmit elevation angle is clamped and controlled in degrees. Based on the above calculations, the beam control module of the fiber optic backbone node applies a hard clamp constraint to the beam pointing angle of the transmitting antenna array. The actual transmit elevation angle is set as... and strictly implement The control criteria. This boundary definition cuts off the physical path for radio frequency waves to escape into free space, allowing signal energy to be efficiently injected into and confined within the waveguide channel close to the sea surface.

[0039] In this invention, after the waveguide parameters are established, the fiber backbone node no longer relies on the traditional digital baseband RF chain, but instead uses an optically reconfigurable smart surface to directly map the optical signal to the RF beam.

[0040] The optical signal carrying high-capacity downlink communication data is intensity-modulated at 1550nm wavelength using an OOK modulation format. After spatial defocusing by a 2x beam expander optical system composed of plano-concave lenses at the front end, it illuminates the back side of the light-controlled reconfigurable smart surface in a perpendicular incidence manner, forming a spatial light intensity distribution field corresponding to the target RF beam direction. Among them, subscript Discrete coordinate indices of different subwavelength physical reflection units in the corresponding array. Characterizes time variables.

[0041] The back-side array of the light-controlled reconfigurable smart surface is directly coupled to a network of photosensitive varactor diodes. Two-dimensional light intensity distribution field. The photosensitive varactor diode junction region on the back of each reflective unit is directly illuminated. Each subwavelength physical reflective unit of the light-controlled reconfigurable smart surface integrates a photosensitive varactor diode. Each photosensitive varactor diode (using a silicon-based PIN varactor) is connected in series with a current-limiting resistor and then uniformly connected to a preset reverse DC bias circuit (the reference voltage of the reverse bias circuit is 5V). Illumination, based on the internal photoelectric effect, excites photogenerated carriers proportional to the light intensity, changing the magnitude of the reverse leakage current of the diode (the range is 1μA~100μA), causing the actual reverse bias voltage across the diode to dynamically change with the light intensity, thereby effectively changing the junction capacitance value of the diode (the range is 0.5pF~5pF, and the mapping relationship between the bias voltage and the junction capacitance is stored in a lookup table through offline calibration), thus forming a bias voltage matrix that varies with the spatiotemporal distribution of light intensity. Each photosensitive varactor diode is electrically connected to its corresponding front-side metal patch via metallized vias. The dynamic change in junction capacitance directly alters the equivalent resonant impedance of the reflective element, ultimately causing a synchronous shift in the amplitude and phase of the complex reflection coefficient of that element. This converts the spatiotemporally varying light intensity signal into a modulation response of the reflection coefficient of each front-side reflective element without delay. Amplitude modulation changes the reflection coefficient amplitude by adjusting the peak light intensity of the corresponding element; the mapping relationship is also stored in a lookup table through offline calibration. Amplitude modulation is introduced to achieve a Taylor taper distribution (e.g., using a Taylor distribution weighted with a -20dB sidelobe level), aiming to reduce the sidelobe level of the RF beam and decrease energy leakage.

[0042] Simultaneously with the photoelectric conversion, the RF generator at the fiber optic backbone node outputs a C-band (4GHz~8GHz) RF microwave local oscillator signal with a constant power envelope, which is then projected onto the front of the optically controlled reconfigurable smart surface at a fixed 30° oblique incidence angle. The target beam pointing angle is set as... The compensation phase for the required reflection coefficient of each unit is calculated using the generalized Snell's law:

[0043] In the formula For free space wavenumber; and The first line, number The horizontal and vertical coordinates of the physical reflection unit in the local coordinate system are then determined. Subsequently, by consulting a pre-calibrated "bias voltage-junction capacitance-reflection phase" mapping table, the required drive bias voltage for each unit is derived. Finally, based on the photoelectric response characteristics of the photosensitive varactor diode, the required back-side spatial light intensity distribution is determined by reverse mapping. After this spatial light intensity interference superposition, a directional radio frequency beam pointing towards the evaporated waveguide layer is formed in the far field, with beam pointing control accuracy better than 1°. The high-frequency surface electromagnetic impedance characteristics of the front-side metal microstructure array are entirely determined by the bias voltage matrix generated on the back side. To implement regulation.

[0044] Define the front side of the smart surface line, number The complex reflection coefficient of the physical reflection unit for the incident radio frequency local oscillator signal is: The fiber optic backbone node utilizes the incident light intensity to alter the resonant state of the surface equivalent circuit, causing the complex reflection coefficient to drift within the complex plane. Its analytical expression is constructed as follows:

[0045] in, The amplitude component represents the frontal reflection coefficient modulated by the bias voltage. The phase component representing the frontal reflection coefficient modulated by the bias voltage. It is the imaginary unit.

[0046] Through the above mechanism, the fiber optic backbone nodes utilize the spatial intensity difference of the incident light signal from the back to achieve joint decoupling modulation of the amplitude and phase of the reflection coefficient of the radio frequency reflecting surface. The radio frequency wavelets reflected by each physical unit interfere and superimpose in the near field space according to the preset phase difference, and directly synthesize a radiated radio frequency field with a specific spatial angular distribution and data envelopment in the far field, completely reconstructing the underlying hardware modulation architecture from baseband to radio frequency.

[0047] This embodiment details the feedforward electromagnetic compensation mechanism by which a relay ship maintains the absolutely stable pointing of a conformal reconfigurable smart surface spatial beam under complex sea state disturbances. The system eliminates the disruption to the line-of-sight link caused by the ship's mechanical deflection at the hardware level by establishing a cross-domain mapping between physical motion and electromagnetic phase.

[0048] The system's underlying layer undergoes pre-testing with offline closed-loop calibration. The average time difference from the moment the sensor triggers a data acquisition command, through bus transmission and algorithm processing, until the oscilloscope captures the actual change in the smart surface diode's bias voltage, is statistically analyzed to determine the inherent system delay from sensor data acquisition and algorithm processing to the completion of the smart surface diode's state switching. During the relay ship's voyage, the shipborne inertial measurement unit collects real-time data on the current moment. Three-dimensional linear acceleration vector and three-dimensional angular velocity vector .

[0049] The relay ship's built-in edge computing unit will combine the aforementioned dynamic vectors at the current moment with the system's inherent delay. The data is synchronously input into a pre-set ship hydrodynamic prediction model. This model, based on the six-degree-of-freedom rigid body motion differential equations of the hull, constructs a 12-dimensional state vector (defined as: ...) containing three-dimensional position, three-dimensional velocity, three attitude angles, and three angular velocities. In the formula, the physical quantities marked with superscripts represent the first derivatives with respect to time, i.e., the linear and angular velocity components. The rigid body motion equations of the hull adopt the six-degree-of-freedom MMG model (the core hydrodynamic derivative parameters of this model are obtained in advance through planar motion mechanism constraint model tests in the ship model tank, or estimated based on the Kijima empirical formula), and the nonlinear wave excitation is modeled as system process noise (process noise covariance matrix). (Based on statistical analysis of actual ship tests at sea state level 3), the three-dimensional linear acceleration and three-dimensional angular velocity collected in real time by the inertial measurement unit were used as observed values ​​(observation noise covariance matrix). The state vector is updated in real time using an extended Kalman filter framework, determined by the IMU device parameters and a filter update frequency of 100Hz. Based on this, a fourth-order Runge-Kutta method is used to perform forward time integration of the rigid body motion equations in 1ms steps, overcoming the system's inherent time lag (inherent delay). Obtained through offline closed-loop calibration (typical value 8ms, calibration accuracy better than 0.5ms), the target time after adding this inherent delay is directly predicted. The corresponding absolute Euler angles represent the absolute hull attitude. The predicted attitude parameters include the hull roll angle. Pitch angle and yaw angle Three Euler angle components. Simultaneously, the incident wave vector. The initial target wave vector is obtained by estimating the angle of arrival of the relay ship's receiving array. The coordinate system is calculated by differential GPS positioning coordinates between the relay ship and the target node in the open sea, and the coordinate system is WGS84 geographic coordinate system.

[0050] Based on the predicted three-dimensional attitude parameters, the system constructs a rotation transformation matrix from the absolute geographic coordinate system to the local coordinate system of the relay ship in the Cartesian coordinate system. This matrix, based on the ZYX rotation order of the local coordinate system, is formed by combining continuous orthogonal rotations around the three fundamental coordinate axes. Its analytical expression is constructed as follows:

[0051] in, Characterizing the yaw rotation operator about the vertical axis. The pitch-rotation operator characterizing the pitch about the transverse axis. The roll rotation operator characterizes the rotation about the longitudinal axis.

[0052] In this invention, the edge computing unit of the relay ship calculates the precise phase compensation amount and extracts the position vector of the conformal reconfigurable intelligent surface physical reflection unit on the relay ship. Simultaneously, in the absolute geographic coordinate system, the direction vector of the incident wave vector incident from the evaporation waveguide layer to the relay ship is calibrated. And the initial target wave vector from the relay ship strictly pointing to the receiving antenna of the distant target node. .

[0053] Because the physical reflection array of the conformal reconfigurable smart surface undergoes a rigid spatial deflection along with the ship's hull, the original beam emission direction deviates from the target node at sea. Therefore, the edge computing unit of the relay ship extracts the inverse matrix of the rotation transformation matrix. This involves mapping the wave vector in absolute space to the local relative space after the ship's deflection. Based on the generalized Snell's law and the phase matching principle, the edge computing units of the relay ship, together with the inverse matrix, the incident wave vector, and the initial target wave vector, calculate the feedforward compensation phase required by each physical reflection unit in the array. Its mathematical constraint equation is:

[0054] In the formula, This represents the equivalent outgoing wave vector mapped to the local coordinate system. This represents the equivalent incident wave vector mapped to the local coordinate system. The vector difference between the two in three-dimensional space is related to the physical unit position vector. By performing an inner product operation, the intrinsic phase gradient correction at that physical location can be obtained.

[0055] The relay ship's edge computing unit iterates through and solves the above formulas to calculate all... The discrete phase shift values ​​required for each physical reflection unit are determined, and modulo 2π operations are performed on each phase shift value to ensure it falls within the engineering adjustable phase range of [0, 2π). Based on this, a complete feedforward compensation phase matrix is ​​constructed. At the target time Upon arrival, the relay ship's baseband control board converts the phase matrix into driving voltage commands for each corresponding unit. Each subwavelength physical reflection unit of the conformal reconfigurable smart surface integrates an electrically adjustable varactor diode. The driving voltage and the unit phase shift are pre-calibrated with a one-to-one mapping relationship. By changing the junction capacitance of the varactor diode, the electromagnetic boundary of the unit is reconfigured, achieving the desired phase compensation. By performing reverse electromagnetic spatial deflection of the incident wave in the microwave band, the system, without relying on any mechanical servo gimbal, uses purely electronic feedforward to cancel the ship's mechanical sway, ensuring that the emitted radio frequency beam stably and accurately locks onto the distant target node.

[0056] This embodiment details the cross-domain reconstruction mechanism based on non-line-of-sight wake scattering when a line-of-sight link fails due to uncontrollable physical obstruction. This mechanism transforms the dynamic wake surface, which is originally a communication interference term, into a passive electromagnetic relay reflector for the radio frequency link, thus reconstructing the physical layer diffraction channel.

[0057] The relay ship utilizes its onboard Ka-band millimeter-wave radar to scan along a ±60° sector on the horizontal plane (range resolution 0.5m, angular resolution 0.2°, capable of detecting ship wakes within 10km ahead through sea surface diffraction in non-line-of-sight environments) to scan and detect the wake area generated by the navigation of the distant offshore target node, acquiring three-dimensional point cloud data of the water surface. The point cloud data is then subjected to surface fitting (using a bicubic B-spline surface fitting algorithm) to obtain the three-dimensional elevation distribution function of the wake of the distant offshore target node. (The spatial grid reference resolution is 0.5m), where and These represent two orthogonal spatial coordinate axes within a horizontal reference plane. To accurately extract the microscopic tilt characteristics of the water surface, the edge computing unit of the relay ship calculates the partial derivatives of the elevation distribution function in the orthogonal directions within the horizontal plane. Specifically, the edge computing unit calculates the partial derivatives along... Elevation gradient along the axis and along Elevation gradient along the axis .

[0058] Based on the elevation change gradient calculated above, the edge computing unit of the relay ship further constructs the local normal vector field at each spatial coordinate point on the surface of the wake water. This normal vector field rigorously characterizes the instantaneous three-dimensional geometric curvature of the dynamic water surface, and its analytical formula is defined as:

[0059] In the formula, the numerator term establishes the unnormalized original normal component at the coordinate point, and the denominator term is the modulus of the normal vector in three-dimensional Euclidean space. The normalized local normal vector field establishes a rigid geometric boundary constraint for the subsequent secondary scattering of electromagnetic waves on this rough water surface.

[0060] In this invention, to ensure that the scattered beam accurately hits the target node in the open sea, the edge computing unit of the relay ship simultaneously constructs the desired reflection wave vector and the theoretical reflection wave vector in a three-dimensional coordinate system. This edge computing unit extracts the absolute coordinates of the receiving antenna of the target node in the open sea and, combined with the three-dimensional coordinates of candidate reflection points in the wake region, calculates in reverse the desired reflection wave vector that can directly deliver the signal to the target receiving antenna. Simultaneously extract the incident wave vector incident from the conformal reconfigurable smart surface of the relay ship onto the surface of the candidate reflection point. .

[0061] Based on the three-dimensional vector form of Snell's law of reflection (i.e., the three-dimensional vector reflection law), the edge computing unit of the relay ship combines the above-mentioned incident wave vector. Local normal vector at the corresponding position The theoretical reflected wave vector after an electromagnetic wave strikes this point is derived in a forward direction. Its mathematical expression is constructed as follows:

[0062] Subsequently, the edge computing unit of the relay ship extracts the hydrodynamic characteristics of the ship's wake and delineates the effective wake divergence angle region constrained by a three-dimensional elevation distribution function (a continuous region for conventional ships of 1,000 tons, with a speed of 10-20 knots, sea state 3 or below, where the length along the ship's course does not exceed 5 times the ship's length, the transverse width does not exceed 2 times the ship's beam, and the standard deviation of elevation fluctuation is greater than 0.1m), and uses this as the finite solution space. Within this defined region, the edge computing unit operates at a preset spatial step size. , The water surface mesh is traversed point by point, and the vector residual cost is evaluated for all candidate water surface reflection points. The expected reflected wave vector is calculated. With theoretical reflected wave vector Three-dimensional vector residuals between :

[0063] The edge computing unit of the relay ship will have a 3D vector residual smaller than a preset residual threshold (set to 0.05). , The effective scattering region is defined as a continuous water surface area (where the wavenumber corresponds to a beam pointing deviation of approximately 3°, satisfying the beam alignment tolerance requirements of the communication link). From this region, the area with the smallest global residual and an area not less than the minimum effective scattering cross section is selected. (Set as equivalent area not less than 9) The boundary of an 8-connected region (with a square area having a side length of 3 times the working wavelength to ensure that the secondary scattered signal power is higher than the receiving sensitivity of the offshore target node) is formally determined as the optimal scattering cross section. At this point, the edge computing unit extracts a three-dimensional direction vector that strictly points towards this optimal scattering cross section. This direction vector is used to completely replace the initial target wave vector of the aforementioned steady-state control stage.

[0064] Relying on the replaced wave vector parameters, the relay ship's edge computing unit restarts the underlying calculation of the compensation matrix. Combining the inverse matrix of the rotation transformation with the position vectors of each physical reflection unit, the edge computing unit recalculates the feedforward compensation phase of each unit in the array to update the feedforward compensation phase matrix. The relay ship's baseband control board converts the updated matrix into control commands, driving the conformal reconfigurable smart surface to perform phase reconstruction and controlling the radio frequency beam to accurately illuminate the determined optimal scattering cross section. After contacting the wake surface of this specific geometry, the radio frequency signal undergoes secondary directional scattering, thereby avoiding physical obstruction and achieving physical layer diffraction relay transmission to the target node in the open sea. In addition to using the ship's wake to achieve diffraction scattering, the physical layer diffraction scattering transmission of this invention can also be achieved using natural or artificial reflectors such as islands, reefs, and sea surface buoys. The scattering cross section search and phase recalculation logic are consistent with the wake scattering scheme, and both fall within the protection scope of this invention.

[0065] This embodiment details the multipath signal processing mechanism and global closed-loop feedback control process at the offshore target node after transmission via physical layer diffraction and scattering. Due to the highly non-uniform geometric undulations of the ship's wake surface, radio frequency signals inevitably experience multipath spatial dispersion and time delay spread after secondary directional scattering at the water surface. The offshore target node, relying on its onboard multi-antenna receiving array, synchronously acquires and digitally down-converts the various multipath components scattered throughout the target sea area.

[0066] To eliminate the degradation of demodulation performance caused by multipath fading, the baseband processing unit of the offshore target node employs a maximum ratio combining mechanism to perform spatial diversity processing on the signals from each receiving antenna branch. The total number of branches in the multi-antenna receiving array of the offshore target node is defined as follows: , No. Each antenna branch receives and down-converts the baseband signal components. The channel fading complex coefficients extracted from the corresponding branch through channel estimation are: Before signal combining, the baseband processing unit independently calculates the weighting coefficients for each branch. To maximize the signal-to-noise ratio at the output, this baseband processing unit strictly constrains the weighting coefficients. It is equal to the complex conjugate of the fading coefficient of the corresponding branch channel, i.e. In addition to maximum ratio combining, multipath combining mechanisms can also employ diversity methods such as equal gain combining and selective combining, all of which can achieve effective superposition and demodulation of multipath signals.

[0067] Based on the established complex conjugate matching criterion, the baseband processing unit of the offshore target node performs a merging operation, and the output of the maximum ratio merged equivalent baseband signal is... The mathematical expression is:

[0068] Through this multipath merging operation, the discrete multipath components that were originally in different spatiotemporal phases are forcibly aligned, achieving in-phase amplitude superposition of the effective signal components of each branch. The baseband processing unit of the offshore target node then processes the merged signal with a high signal-to-noise ratio. Carrier synchronization, symbol synchronization, and baseband demodulation are performed sequentially to accurately recover the wide-area communication payload data initially sent by the fiber optic backbone node.

[0069] While completing data demodulation, the channel estimation module of the offshore target node extracts the current physical layer channel state information in parallel, and measures the instantaneous signal-to-noise ratio and bit error rate parameters of the equivalent baseband signal in real time. The offshore target node encapsulates these key indicators characterizing the underlying transmission quality and generates a standardized link receive status feedback frame. This feedback frame is transmitted across domains through an independent reverse control channel link established by the VHF radio or satellite communication module on the offshore target node (i.e., the link monitoring data and the link status feedback frame share the same reverse control channel), and is finally received and parsed by the fiber optic backbone node at the source end.

[0070] The fiber optic backbone nodes execute global closed-loop feedback control based on the resolved link reception status. The offshore target nodes send a link status feedback frame every 100ms, containing instantaneous signal-to-noise ratio (SNR), bit error rate (BER), and delay spread. When the SNR of three consecutive feedback frames monotonically decreases and the cumulative attenuation exceeds 3dB, a continuous attenuation trend is identified, and the main control unit triggers reverse calibration logic. The fiber optic backbone nodes employ an incremental PID control algorithm, using the SNR deviation as input and outputting the adjustment amount of the transmission elevation angle. The minimum adjustment step is 0.1°. Based on the attenuation gradient, the corrected refractive index extremum parameters of the evaporating waveguide layer and the updated critical elevation angle are recalculated. By recalculating the phase distribution of the reflection coefficient of each unit of the optically reconfigurable smart surface, the transmission elevation angle of the RF beam is dynamically reduced electronically to enhance the energy coupling density within the waveguide. Simultaneously, after receiving the compensation signaling derived from the status feedback, the relay ship calibrates the inherent system delay parameters in the preset prediction model online every 10 minutes based on the feedback delay statistics (calibration accuracy 0.1ms). On the other hand, it corrects the calibration value of the target wave vector based on the feedback signal-to-noise ratio deviation (correcting the azimuth and elevation angles of the target wave vector with a correction step size of 0.2°), and recalculates the feedforward compensation phase matrix. In this way, it finely adjusts the spatial beam pointing of the conformal reconfigurable smart surface, and completely completes the end-to-end adaptive closed-loop iteration from the transmitter, relay, to the receiver.

[0071] In this invention, to support the stable operation of the above-mentioned method in the physical world, the various control and calculation steps within the system architecture are implemented using dedicated electronic equipment. This electronic equipment has an internal hardware bus connected to a high-frequency processor, non-volatile memory, and a radio frequency communication interface. The memory persistently stores the complete computer program instructions, from environmental modeling, attitude prediction, compensation matrix calculation to wake scattering search. The high-frequency processor directly controls the electromagnetic state of the underlying optoelectronic devices and antenna array by calling these instructions. The entire system is also permanently stored in a computer-readable storage medium to ensure the accurate execution of the various hydrodynamic prediction algorithms and electromagnetic wave field control rules.

[0072] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for long-distance signal transmission in near-shore waters based on fiber optic signal distribution and shipborne relay, applied to a near-shore communication system including fiber optic backbone nodes and relay vessels, characterized in that: include: Based on the sea surface meteorological environment parameters collected by the fiber backbone node, a corrected refractive index profile of the evaporation waveguide layer is established and the transmission elevation angle is determined. The fiber backbone node generates an optical signal carrying communication data. The optical signal is modulated into a radio frequency signal and injected into the marine evaporation waveguide layer using the optically controllable reconfigurable smart surface at the fiber backbone node. The relay ship receives the radio frequency signal, predicts the absolute Euler angle of the ship at the target time based on the preset ship hydrodynamic prediction model, calculates the feedforward compensation phase matrix to reconstruct the phase of the conformal reconfigurable smart surface on the relay ship, and realizes steady-state control of beam pointing towards the target node in the open sea. When the line-of-sight link between the relay ship and the offshore target node fails, the relay ship obtains the three-dimensional elevation distribution function of the wake of the offshore target node, searches for the optimal scattering cross section that conforms to the three-dimensional vector reflection law, and recalculates the feedforward compensation phase matrix based on the direction of the optimal scattering cross section to adjust the direction of the radio frequency beam and realize physical layer diffraction scattering transmission to the offshore target node.

2. The near-shore long-distance signal transmission method based on fiber optic signal distribution and shipborne relay according to claim 1, characterized in that, Determining the launch elevation angle includes: Based on the modified refractive index profile of the evaporated waveguide layer that varies with height, the minimum modified refractive index within the waveguide layer and the modified refractive index at the height of the fiber backbone node antenna are determined. The critical elevation angle for transmission is calculated based on the minimum corrected refractive index and the corrected refractive index at the height of the fiber optic backbone node antenna, and the actual transmission elevation angle is limited to the critical elevation angle for transmission.

3. The near-shore long-distance signal transmission method based on fiber optic signal distribution and shipborne relay according to claim 1, characterized in that, The method of modulating optical signals into radio frequency signals using a light-controlled reconfigurable smart surface includes: The optical signal is amplified and incident onto the back side of the optically reconfigurable smart surface, and the bias voltage of the photosensitive varactor diode on the back side is changed according to the spatiotemporal distribution of the optical signal. Radio frequency microwave local oscillator signals are incident on the front side of the optically reconfigurable smart surface. The intensity of the optical signal is used to simultaneously modulate the amplitude and phase of the front reflection coefficient, generating a radiating radio frequency field with spatial angle, thereby realizing the direct mapping of the optical signal to the radio frequency beam.

4. The near-shore long-distance signal transmission method based on fiber optic signal distribution and shipborne relay according to claim 1, characterized in that, The prediction of the absolute Euler angles of the hull at the target time based on the pre-set hull hydrodynamic prediction model includes: The inherent system delay is obtained, and the three-dimensional linear acceleration vector, three-dimensional angular velocity vector of the relay ship at the current moment, and the inherent delay are collected by the inertial measurement unit and input into the ship hydrodynamic prediction model. Predict the ship's roll angle, pitch angle, and yaw angle at the target time after superimposing the inherent delay on the current time, and construct a rotation transformation matrix accordingly.

5. The near-shore long-distance signal transmission method based on fiber optic signal distribution and shipborne relay according to claim 4, characterized in that, The calculation of the feedforward compensation phase matrix includes: Obtain the position vector, incident wave vector direction vector, and initial target wave vector pointing to the offshore target node of the conformal reconfigurable smart surface physical reflection unit; By combining the inverse of the rotation transformation matrix, the position vector, the incident wave vector direction vector, and the initial target wave vector, the feedforward compensation phase of each physical reflection unit is calculated to construct the feedforward compensation phase matrix.

6. The near-shore long-distance signal transmission method based on fiber optic signal distribution and shipborne relay according to claim 1, characterized in that, After obtaining the three-dimensional elevation distribution function of the wake of the offshore target node, the method further includes: The elevation change gradient is obtained by calculating the partial derivatives of the three-dimensional elevation distribution function in the directions of the two orthogonal coordinate axes in the horizontal plane. Based on the elevation change gradient, a local normal vector field is constructed at various points on the surface of the wake water body.

7. The near-shore long-distance signal transmission method based on fiber optic signal distribution and shipborne relay according to claim 6, characterized in that, The search for the optimal scattering cross section that conforms to the three-dimensional vector reflection law includes: The desired reflected wave vector is constructed based on the coordinates of the receiving antenna of the offshore target node and the candidate reflection point of the wake. The theoretical reflected wave vector is calculated based on the incident wave vector of the relay ship hitting the wake surface and the local normal vector field. The optimal scattering cross section is determined by traversing the effective wake divergence angle region constrained by the three-dimensional elevation distribution function and minimizing the vector residual between the desired reflected wave vector and the theoretical reflected wave vector.

8. The near-shore long-distance signal transmission method based on fiber optic signal distribution and shipborne relay according to claim 5, characterized in that, The step of recalculating the feedforward compensation phase matrix based on the direction of the optimal scattering cross section to adjust the RF beam pointing includes: Obtain the direction vector pointing to the optimal scattering cross section; The initial target wave vector is replaced by the direction vector, and the feedforward compensation phase of each physical reflection unit is recalculated to update the feedforward compensation phase matrix, thereby controlling the radio frequency beam to illuminate the optimal scattering cross section for secondary scattering.

9. The near-shore long-distance signal transmission method based on fiber optic signal distribution and shipborne relay according to claim 1, characterized in that, Both the optically reconfigurable smart surface and the conformal reconfigurable smart surface are composed of multiple subwavelength physical reflection units arranged in an array.

10. The near-shore long-distance signal transmission method based on fiber optic signal distribution and shipborne relay according to claim 1, characterized in that, After being transmitted via diffraction and scattering through the physical layer, the radio frequency signal undergoes multipath merging and baseband demodulation at the offshore target node, and the corresponding link reception status is fed back to the fiber optic backbone node for dynamically adjusting the transmission elevation angle and beam pointing.

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