Cooperative 5g signal-based water surface fluctuation height measurement method and system

Abstract

The present application relates to a kind of water surface fluctuation height measurement method and system based on cooperative 5G signal, belong to hydrological environment high-precision monitoring technical field.The present application utilizes three known positions of 5G base station configured in the periphery of water area, follows 5G standard and locks two physically separated effective scattering patches on water surface in A-B and A-C link respectively by discrete beam scanning;Subsequently, the CSI of reflected signal and direct signal is extracted and the innovative difference elimination equation is constructed, to cancel the independent initial phase error introduced by local oscillator between base stations from the level of pure algebra;Then, the "vernier effect" is used to filter out the sudden noise of water surface, and finally, through the unified three-dimensional space Jacobian partial derivative matrix based on mirror method, the horizontal coordinate difference of the two different address reflection patches is perfectly absorbed, and the real water surface unified overall macro fluctuation height is accurately inverted.

Description

Technical Field

[0001] This invention belongs to the fields of integrated sensing and wireless communication (ISAC) and high-precision monitoring of hydrological environment, and relates to a method and system for measuring water surface rise and fall height based on cooperative 5G signals. Background Technology

[0002] Real-time, continuous, and accurate water level monitoring plays a crucial supporting role in flood control and drainage early warning, optimized water resource allocation, navigation safety, and aquatic ecological environment protection. Traditional hydrological monitoring methods mainly rely on contact sensors (such as float-type water level gauges and submersible pressure water level gauges) and non-contact physical detection equipment (such as ultrasonic water level gauges and dedicated radar water level gauges). However, contact sensors must be inserted into the water body, resulting in high installation and maintenance costs, and they are highly susceptible to damage from floodwater flow, siltation, and floating debris. While dedicated radar or ultrasonic water level gauges avoid contact with the water body, they require the erection of large support towers and independent power and communication lines along the waterway, making it difficult to achieve large-scale, high-density, low-cost network coverage across a vast watershed.

[0003] Entering the 5G-Advanced and 6G era, Integrated Information and Communication Capabilities (ISAC) technology endows ubiquitous cellular network base stations with radar sensing and environmental reconstruction capabilities. However, existing carrier phase deformation monitoring technologies based on 5G OFDM signals face three major challenges in water surface scenarios due to underlying physical and protocol mechanisms: First, the asynchronous nature of multiple base stations. When using distributed multi-base station collaboration, different base stations have independent local oscillators, making it difficult to achieve accurate carrier initial phase synchronization. This asynchronous clock drift completely overshadows the real spatial phase transitions caused by millimeter-level undulations on the water surface. Second, the non-reflective scattering and wave jump problems of real water surfaces. Real river surfaces are accompanied by wind and waves, and high-frequency waves can cause extremely strong phase flicker and integer cycle ambiguity failure. Third, the separation of physical reflection points in multiple transmit and receive links and the constraints of 5G underlying beamforming protocols. In a three-node architecture with one transmitting base station and two receiving base stations (i.e., AB link and AC link), according to the bistatic radar geometry law of electromagnetic wave propagation, the shortest reflection path from A to B and the shortest reflection path from A to C must intersect at two physical reflection points with completely different coordinates on the water surface. However, in the actual 3GPP 5G protocol stack, the beamforming of the base station relies on a predefined discrete beam codebook (such as the precoded matrix indicator PMI), making continuous illumination impossible. This means that transmitting base station A must select different transmit beams for these two physically separate reflection points, while receiving base stations B and C must also independently find the optimal receive beam using their respective codebooks. Existing technology has not yet solved the problem of how to independently lock these "two separate water surface reflection patches" using discrete codebook protocols and unify their spatial coordinate differences into the final water level height calculation model.

[0004] In summary, overcoming clock asynchrony errors in distributed architectures, independently decoupling and tracking the separated rough scattering surface of water by combining 5G standard beamcodebooks, and breaking through the limitations of traditional one-dimensional unwinding algorithms to suppress complex fluctuations are key technical challenges that urgently need to be addressed for the implementation of integrated communication and sensing applications. Summary of the Invention

[0005] The purpose of this invention is to provide a method and system for measuring water surface rise and fall height based on cooperative 5G signals. It utilizes the frequency domain channel state information of the mutual transmission and reception signals of three distributed 5G communication base stations, determines the independent effective scattering surface in physically separated areas through 3GPP beamcode scanning, constructs a three-node phase differential closed loop to eliminate asynchronous clock errors, combines a subcarrier diversity multi-frequency dewinding algorithm to suppress water surface wave noise, and finally uses a three-dimensional geometric Jacobian matrix to uniformly invert the overall rise and fall height of the water surface on a large scale, completing millimeter-level non-contact precise measurement.

[0006] This invention provides the following technical solution: On the one hand, a method for measuring water surface rise and fall height based on cooperative 5G signals is provided, the method comprising: S1. Select several communication base stations around the water surface to be measured and establish a corresponding spatial reference model and beam codebook mapping table. S2. Select one base station and independently perform beam scanning mapping to the other base stations. Determine the corresponding optimal beam combination based on the dual reflection points and lock the independent effective scattering patches. S3. Based on the optimal wave velocity combination and the effective scattering plate, extract the reflection channel CSI from the OFDM sensing reference signal transmitted by the transmitting base station to the other receiving base stations, and extract the high-resolution carrier phase observation sequence of the center subcarrier and multiple edge subcarriers from it. S4. Perform multi-node phase differential operation on each extracted subcarrier frequency component. Through algebraic differential compensation operation, offset and cancel the independent local initial clock phase drift variables of all base stations to obtain a pure differential geometric phase sequence. S5. The obtained pure differential geometric phase value sequence is fed into an adaptive Kalman filter to dynamically track and separate the high-frequency phase jitter component caused by random water waves, and extract the stable phase envelope that reflects the trend evolution of the macro water level. S6. Based on subcarrier diversity, multi-frequency collaborative unwinding and dual-patch geometric inversion calculation are used to solve for the true vertical rise and fall height of the unified water surface, which is not affected by the difference in the horizontal coordinates of the reflecting surface.

[0007] Further, in step S1, three base stations are selected, with one base station serving as the transmitting node and the remaining base stations as receiving nodes; corresponding phase center coordinates are established based on the positions of all base stations; and a mapping table is established between each precoding matrix indicator (PMI) and its actual corresponding three-dimensional spatial physical two-dimensional angle based on the transmitting and receiving beamcodebooks of the communication base stations.

[0008] Furthermore, in step S2, the transmitting base station is controlled to perform independent beam scanning mapping to the two receiving base stations, and the different transmission links form two reflection points on the water surface, and the two reflection points are physically separated. Then, based on the received power or signal-to-noise ratio, a traversal scan is performed to evaluate and lock the optimal beam combination on different transmission links, denoted as follows: , and will , The spatial intersection area was determined as the first effective scattering patch and the second effective scattering patch on the water surface; where, the subscript Represents the transmitting base station, subscript These represent two receiving base stations.

[0009] Further, in step S3, the transmitting base station transmits OFDM broadband signals containing probe reference sequences to the other receiving base stations based on the locked optimal beam combination, and extracts the reflection channel CSI reflected from the corresponding effective scattering plate to the corresponding receiving base station; then, it extracts the frequency-specific signal from the reflection channel CSI. The center subcarrier and frequency are High-resolution CSI carrier phase sequence for specific edge subcarriers; Simultaneously, the base stations receive reference signals from each other using known directional beams for line-of-sight mutual transmission, and extract the carrier phase on the direct physical link.

[0010] Furthermore, in step S4, multi-node phase differential operation is performed on each extracted subcarrier frequency component. Specifically, the reflected carrier phase of another receiving base station and the mutual direct signal carrier phase between the two receiving base stations are successively subtracted from the reflected carrier phase of one receiving base station to obtain a pure differential geometric phase sequence.

[0011] Furthermore, in step S4, it is assumed that the reflected carrier phase of one of the receiving base stations is in any subcarrier frequency. The phase observation equation below is expressed as:

[0012] In the formula, This represents the total electromagnetic wave propagation distance of the reflected link from transmitting base station A to receiving base station B at time t. This represents the initial random phase drift introduced by the independent local oscillator source of transmitting base station A. This represents the initial random phase drift introduced by the independent local oscillator source of the receiving base station B. This represents the phase integer ambiguity and residual noise term of the reflection link from transmitting base station A to receiving base station B; Suppose the phase of the reflected carrier of another receiving base station is in any subcarrier frequency The phase observation equation below is expressed as:

[0013] In the formula, This represents the total electromagnetic wave propagation distance of the reflected link from transmitting base station A to receiving base station C at time t. This represents the initial random phase drift introduced by the independent local oscillator source of the receiving base station C. This represents the phase integer ambiguity and residual noise term of the reflection link from transmitting base station A to receiving base station C; Suppose that the carrier phase of the direct transmission signals between two receiving base stations is in any subcarrier frequency. The phase observation equation below is expressed as:

[0014] In the formula, This represents the fixed linear distance between receiving base station B and receiving base station C. This represents the phase integer ambiguity and residual noise term of the direct link between receiving base station B and receiving base station C; Finally, the integrated differential phase parameters are constructed by measuring the nodes. After expansion and simplification, the equation finally converges to:

[0015] in, This represents the residual combined integer ambiguity and the noise of the combined system. .

[0016] Furthermore, in step S6, by utilizing the stationary phase evolution characteristics of the center and edge frequency subcarriers, a multi-frequency cooperative unwinding equation is constructed through the "vernier effect" to directly recover the absolute change in the physical differential path length without jumps; although the two reflective patches are separated from each other in horizontal position, they are both located on the same large-scale macroscopic water surface, that is, they share the same absolute altitude parameter. Then, the change in physical path length is substituted into the Jacobian partial derivative matrix composed of the three-dimensional coordinates of the base station. The partial derivative model based on the virtual image principle mathematically adaptively absorbs the different horizontal coordinates of the patch, and the overall vertical macroscopic rise and fall height of the real water surface is calculated in reverse through Taylor expansion.

[0017] Furthermore, in step S6, the specific mathematical logic of the multi-frequency cooperative unwinding mechanism based on OFDM subcarrier diversity is as follows: Extraction frequency is and The pure differential phase sequence after dual-frequency subcarrier processing; Constructing the cooperative phase difference between two frequencies ; Based on the vernier effect, the equivalent large wavelength of dual-frequency co-synthetic synthesis is ; Without relying on the historical constraints of adjacent samples, the formula is used. It can directly recover the total absolute physical differential path change without jumps in a single snapshot.

[0018] Furthermore, in step S6, the spatial geometric inversion solution mechanism for height variation under dual-patch separation is as follows: Based on the known antenna phase center coordinates , , Let the absolute elevation of the current macroscopic water surface to be measured be the plane. ; Based on the principle of the mirror virtual image method in three-dimensional space, the transmitting base station A is mapped as an equivalent virtual image source below the water surface. The coordinates are Regardless of the actual reflective patch... The equivalent absolute shortest propagation distance of electromagnetic waves along links AB and AC, depending on their location on the plane, is determined by the following nonlinear function:

[0019]

[0020] The total length of the differential path is:

[0021] Using height parameters Taking the partial derivative of the change with respect to the total length of the differential path yields the Jacobian coefficient matrix, which reflects the spatial projection gradient relationship; when the change in the differential path is calculated... At that time, by using the inverse operation of the first-order linearized matrix, the true vertical rise and fall height of the uniform water surface, which is unaffected by the difference in the horizontal coordinates of the reflecting surface, can be solved. .

[0022] On the other hand, a system for implementing the aforementioned method for measuring water surface rise and fall height based on cooperative 5G signals is also provided, the system comprising: Base station network and codebook management module: includes at least three communication base stations, maintains the 3GPP discrete beam codebook and performs spatial angle mapping; Independent Patch Tracking and Multi-Frequency CSI Extraction Module: Performs two-dimensional beam space traversal scanning, decouples and locks the two sets of optimal PMIs corresponding to two physically separated effective scattering patches on the water surface in a bistatic multi-receiver node environment, and extracts multi-subcarrier high-resolution carrier phase. Phase error elimination operation module: executes the core algorithm of multi-node three-element phase closed-loop differential logic, and uses mutual direct signals to completely offset and cancel the clock drift error caused by the independent local oscillator source of each base station; Multi-frequency unwinding and dual-patch geometric inversion module: It integrates OFDM subcarrier vernier effect to directly recover absolute path increment, combines adaptive Kalman filtering to suppress high-frequency clutter, and uses virtual image Jacobian matrix to inversely map the micro-path change containing information of two different spatial reflection points into a unified physical vertical macro-reservoir water level height.

[0023] The beneficial effects of this invention are as follows: Deeply compatible with 3GPP codebook and decoupling of heterogeneous dual-patch beams: This invention breaks the unrealistic assumption that traditional multi-receiver radars must illuminate the same physical patch. Addressing the inherent discrete characteristics of beamcodebooks in distributed communication base stations, this invention creatively designs a "two-set PMI combined independent scanning and locking" strategy. This strategy acknowledges and utilizes the fact that the reflection points of the AB and AC paths are physically separated (two different patches), directly aligning with the beam management protocol of commercial 5G basebands.

[0024] Spatial Virtual Image Inversion Eliminates Position Dependency: This invention proposes a unified Jacobian partial derivative model based on the 3D absolute coordinate mirror image method. This model has significant advantages in mathematical computation: as long as the water surface to be measured is a locally uniform horizontal plane (with the same large-scale macroscopic elevation), it will be effective. This model perfectly absorbs and shields the coordinate differences in latitude and longitude between the two independent scattering patches, making it completely unnecessary for the system to know the true reflection point. Coordinates can be used to accurately converge to and inversely derive the global vertical water level from pure distance variables. .

[0025] Breaking through the hardware bottleneck of clock synchronization and achieving extremely simplified deployment: This invention proposes a "three-node signal closed-loop mutual transmission differential cancellation" mechanism. It completely eliminates the need for laying expensive PTP fiber optic synchronization networks between base stations or using external high-precision GPS atomic clocks. Through algebraic differential processing at the software level, it perfectly eliminates the malicious random phase deflection errors caused by the three independent local oscillators, greatly reducing the network construction cost of the sensing network.

[0026] Anti-wave jump unwrapping capability based on subcarrier diversity: This invention fully leverages the advantages of 5G OFDM broadband multi-carrier technology and innovatively introduces a multi-frequency collaborative unwrapping mechanism based on the "vernier effect." It constructs a very large "synthetic equivalent wavelength" (e.g., 3 meters), achieving direct recovery of the absolute physical phase in a single snapshot, completely eliminating severe system measurement fly-points caused by the turbulence of large river waves.

[0027] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0028] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein: Figure 1This is a flowchart illustrating the water surface rise and fall height measurement method based on cooperative 5G signals according to an embodiment of the present invention; Figure 2 This is a schematic diagram of a base station selection scenario according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the topological distribution of three-dimensional spatially disparate dual-patch structures according to an embodiment of the present invention; Figure 4 This is a schematic diagram showing the comparison and error assessment of water surface height phase trends in an embodiment of the present invention. Detailed Implementation

[0029] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0030] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0031] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0032] Please see Figures 1-4 This invention relates to a method and system for measuring water surface rise and fall height based on cooperative 5G signals.

[0033] This invention utilizes three 5G base stations located at known positions around a body of water. Following 5G standards, discrete beam scanning is used to locate two physically separated effective scattering patches on the water surface, representing AB and AC links respectively. Subsequently, the CSI of the reflected and direct signals is extracted, and an innovative differential elimination equation is constructed to cancel the independent initial phase error introduced by the local oscillator between base stations from a purely algebraic perspective. Furthermore, the "vernier effect" is used to filter out abrupt noise on the water surface. Finally, a unified three-dimensional Jacobian partial derivative matrix based on the image method perfectly absorbs the difference in horizontal coordinates between the two disparate reflection patches, accurately reproducing the unified overall macroscopic fluctuation height of the real water surface. Specifically, its detailed implementation process includes: Example 1 This embodiment describes a method for measuring water surface rise and fall height based on cooperative 5G signal carrier phase, such as... Figure 1 As shown, it includes the following core steps: Step 1: Establish the spatial reference model and beam codebook mapping.

[0034] Obtain the precise three-dimensional absolute position coordinates of three 5G communication base stations A (transmitting node), B, and C (receiving node) configured around the water surface to be measured; extract the discrete transmit beam codebook and receive beam codebook of the base stations based on the 3GPP standard configuration, and establish a mapping table between each precoding matrix indicator (PMI) and its actual corresponding three-dimensional physical two-dimensional angle (azimuth and elevation angle).

[0035] Step 2: Beam scanning and independent effective scattering patch locking at dual reflection points.

[0036] The system uses an altitude measurement system to schedule and control base station A to perform independent beam scanning mapping with base stations B and C, respectively. Due to the different spatial locations of the receiving base stations, electromagnetic waves will inevitably form a first reflection point corresponding to the AB link and a second reflection point corresponding to the AC link on the water surface. These two reflection points are physically separated. The system performs an ergonomic scan based on received power or signal-to-noise ratio, evaluating and locking two independent optimal PMI combinations: locking the first optimal beam combination. The spatial intersection area is defined as "effective scattering patch 1" on the water surface; the second set of optimal beam combinations is locked. The spatial intersection area is defined as the "effective scattering patch 2" on the water surface.

[0037] Step 3: Channel State Information (CSI) separation and multi-frequency phase extraction.

[0038] Based on two locked sets of different beam combinations, base station A transmits OFDM sensing reference signals to the water surface using a time-division multiplexing method. The baseband processor extracts the reflection channel CSI reflected from patch 1 to B and the reflection channel CSI reflected from patch 2 to C; simultaneously, base station B and base station C exchange reference signals using line-of-sight (LOS) to obtain the direct CSI. Then, high-resolution carrier phase observation sequences of the center subcarrier and multiple edge subcarriers are synchronously extracted from each set of CSIs.

[0039] Step 4: Elimination of multi-node carrier phase differential and asynchronous error offsetting.

[0040] For each extracted subcarrier frequency component, a multi-node phase differential operation is performed. The AC reflected carrier phase received by base station C is subtracted from the AB reflected carrier phase received by base station B, and the carrier phase of the direct signal transmitted between BC is further subtracted. Through this specific algebraic differential compensation operation, the independent local initial clock phase drift variables of the three base stations are completely offset and canceled, resulting in a pure differential geometric phase sequence.

[0041] The specific mathematical logic and mechanism for multi-node carrier phase differential and asynchronous error offsetting and elimination are as follows: 1. When the path link is: Base station A transmits (beam 1) → patch 1 reflects → base station B receives, it is in any subcarrier frequency The phase observation equation below is expressed as:

[0042] 2. When the path link is base station A transmitting (beam 2) → patch 2 reflection → base station C receiving, it is in any subcarrier frequency The phase observation equation below is expressed as:

[0043] 3. The path link is a direct interconnection link between base station B and base station C, which exists in any subcarrier frequency. The phase observation equation below is expressed as:

[0044] Based on the three fundamental observation equations mentioned above, the system internally constructs a comprehensive differential phase parameter through measurement nodes. :

[0045] After unfolding, all independent initial hardware phase drift terms , , All of them cancel each other out, and the final equation converges to:

[0046] This mechanism enables low-level coherent phase synchronization without any hardware-level fiber optic clock synchronization.

[0047] Step 5: Adaptive filtering of multidimensional water surface fluctuation noise.

[0048] The obtained pure differential geometric phase value sequence is fed into an adaptive Kalman filter (AHKF); the high-frequency phase jitter component caused by random water waves is dynamically tracked and separated, and the stable phase envelope reflecting the macroscopic water level trend evolution is smoothly extracted.

[0049] Step 6: Multi-frequency cooperative unwrapping and dual-patch geometric inversion solution based on subcarrier diversity.

[0050] By utilizing the stationary phase evolution characteristics of the center and edge frequency subcarriers, a multi-frequency cooperative unwinding equation is constructed through the "vernier effect" to directly recover the absolute, non-jumping physical differential path length change. Although the two reflective patches are horizontally separated, they are both located on the same large-scale macroscopic water surface (i.e., sharing the same absolute elevation parameter). The change in physical path length is substituted into the Jacobian partial derivative matrix composed of the three-dimensional coordinates of the base station. The partial derivative model based on the virtual image principle mathematically adaptively absorbs the different horizontal coordinates of the patches, and calculates the overall vertical macroscopic rise and fall height of the real water surface through Taylor expansion.

[0051] The specific mathematical logic of the multi-frequency cooperative unwinding mechanism based on OFDM subcarrier diversity is as follows: Extraction frequency is and The purified differential phase sequence after dual-frequency subcarrier processing. Constructing the cooperative phase difference between the two frequencies. Based on the vernier effect, the equivalent large wavelength of dual-frequency co-synthetic synthesis is... The system does not rely on historical constraints from adjacent samples, and is achieved through the formula... It directly recovers the total absolute physical differential path change without jumps under a single snapshot, solving the phase flip (2π winding) failure problem caused by sudden wave changes.

[0052] The spatial geometric inversion solution mechanism for height variation under dual-patch separation is as follows: Based on the known antenna phase center coordinates , , Let the absolute elevation of the current macroscopic water surface to be measured be the plane. .

[0053] Even though the actual horizontal and vertical coordinates of patch 1 and patch 2 are unknown and different, based on the principle of the mirror virtual image method in three-dimensional space, the transmitting base station A is mapped as an equivalent virtual image source below the water surface. The coordinates are Regardless of the actual reflective patch... The equivalent absolute shortest propagation distance experienced by electromagnetic waves in the AB and AC links, depending on their location on the plane, is strictly determined by the following nonlinear function:

[0054]

[0055] The total length of the differential path is:

[0056] Using height parameters Taking the partial derivative of the change with respect to the total differential path length yields the Jacobian coefficient matrix, which reflects the spatial projection gradient relationship. When the system calculates the change in the differential path... At that time, by using the inversion operation of the first-order linearized matrix, the true vertical rise and fall height of the uniform water surface, which is unaffected by the difference in the horizontal coordinates of the reflecting surface, can be accurately solved. .

[0057] Example 2 This embodiment provides a system for implementing the method in Embodiment 1 above, the system comprising: Base station network and codebook management module: includes at least three 5G base stations, maintains 3GPP discrete beam codebook and performs spatial angle mapping; Independent Patch Tracking and Multi-Frequency CSI Extraction Module: Performs two-dimensional beam space traversal scanning, decouples and locks the two sets of optimal PMIs corresponding to two physically separated effective scattering patches on the water surface in a bistatic multi-receiver node environment, and extracts multi-subcarrier high-resolution carrier phase. Phase error elimination operation module: executes the core algorithm of multi-node three-element phase closed-loop differential logic, and uses mutual direct signals to completely offset and cancel the clock drift error caused by the independent local oscillator source of each base station; Multi-frequency unwinding and dual-patch geometric inversion module: It integrates OFDM subcarrier vernier effect to directly recover absolute path increment, combines adaptive Kalman filtering to suppress high-frequency clutter, and uses virtual image Jacobian matrix to inversely map the micro-path change containing information of two different spatial reflection points into a unified physical vertical macro-reservoir water level height.

[0058] Specifically, in this embodiment, three 5G base stations with a certain spatial topological distribution are selected around the water area to be monitored (reservoir dam or wide river surface), such as... Figure 3As shown, the system is defined as transmitting node A and cooperating receiving nodes B and C. A global WGS-84 or Cartesian coordinate system is established to accurately calibrate the phase center coordinates of the antenna arrays of these three nodes. .

[0059] Specifically, in this embodiment, taking base stations A=[0,0,45], B=[80,0,42], and C=[250,150,38] as examples, the distances between base stations A, B, and C are calculated using the following formula:

[0060] Substituting the coordinates of base stations A, B, and C respectively, we get:

[0061]

[0062]

[0063]

[0064]

[0065]

[0066] Among them, the height of the transmitting base station A is 45 meters, the receiving base station B is close and has a steep elevation angle, and the receiving base station C is far away and has a gentle elevation angle.

[0067] Due to antenna array limitations, modern 5G base stations employ discrete beamcodebooks (Type I codebooks) based on 3GPP specifications (such as Release 15 / 16). During system initialization, the transmission beamcodebook set of base station A is read. and the receive beam codebook sets of base stations B and C Establish a lookup table that maps precoded matrix indicators (PMI) to physical space azimuth and elevation angles.

[0068] This embodiment addresses the electromagnetic waves exhibiting bistatic scattering characteristics on the vast river surface, characterized by rough waves and strong winds. Specifically, in a bistatic radar topology consisting of stations A, B, and C, the shortest path of specular reflection from A to B and the shortest path from A to C result in two completely different points of contact on the actual water surface. During beam training, station A must employ time-division multiplexing to perform two sets of beam scans. For patch locking at base station B: Base station A scans using its transmitted codebook, while base station B cooperates with the received scan. The base station algorithm layer locks the first optimal beam combination based on the maximum received power or RSRP. The energy convergence zone of this group of beams constitutes the "effective scattering patch 1" on the physical water surface.

[0069] For patch locking at base station C: base station A adjusts its scanning direction, and base station C cooperates in receiving the signal. The system then locks onto the second optimal beam combination based on the same principle. The energy convergence zone of this group of beams constitutes an "effective scattering patch 2" far from patch 1, such as... Figure 3 The diagram shows the topological distribution of two patches located at different locations in three-dimensional space.

[0070] During the actual continuous water level monitoring phase, base station A utilizes locked [data] in different time slots (or by using multi-beam concurrency). and The transmission included a broadband OFDM signal containing a probe reference sequence.

[0071] Base station B synchronously extracts the frequency of the center subcarrier from the reflected echo of patch 1, and base station C extracts the frequency of the center subcarrier from the reflected echo of patch 2. ) and specific edge subcarriers (frequency) The high-resolution CSI carrier phase sequence is used. In this embodiment, the center subcarrier f1 = 4.9 GHz (Sub-6 GHz), and the frequency difference between the edge subcarrier f2 and the center subcarrier is 100 MHz.

[0072] At the same time, base stations B and C use known directional beams to exchange reference signals at line-of-sight (LOS) and extract the carrier phase on the direct physical link.

[0073] At this time, the local oscillators of each base station are still drifting uncontrollably. Measurement nodes are targeting specific frequency points. The core equations of the difference scalar were constructed as follows:

[0074] This will include their respective random hardware clock initial error variables. , , Substituting the theoretical observations into the above equation, and performing algebraic elimination, due to the connectivity of the closed-loop topology, all unpredictable hardware phase noise is 100% strictly canceled out in this difference term. The output sequence is the relatively clean spatial difference geometric phase value between the two links.

[0075] Will target , The clean phase sequences after offsetting the two independent frequency points are respectively fed into the Sage-Husa adaptive Kalman filter, which intelligently removes the zero-mean high-frequency flicker caused by the physical abrupt changes in water surface wind and waves, and retains the macroscopic gradual trend.

[0076] Subsequently, the vernier coordination effect of dual-frequency subcarriers was used to calculate:

[0077] Using synthesized wavelengths that have been amplified hundreds or thousands of times (For example, at the meter level), the system can directly calculate the unambiguous microscopic physical differential path length increment using a single time-series snapshot. This overcomes the risk of one-dimensional time-domain strong solution entanglement and carry-over collapse caused by localized large waves on the water surface.

[0078] The final step involves a geometric inversion from microwave distance variation to macroscopic water level variation in nature. The underlying mathematical model of this invention possesses strong tolerance: even considering the true horizontal coordinates of effective scattering patches 1 and 2 on the water surface. Completely different and the system cannot know precisely, as long as the water area has a uniform macroscopic elevation within the monitoring span. The model still holds true.

[0079] Based on the principle of spatial mirror virtual image method, the transmitting antenna A is crossed Virtual image points are produced by mirroring the horizontal plane. According to the theorem that the straight-line distance between two points in space is the shortest, regardless of the location of the reflection point on the water surface, the unique analytical solutions for the shortest reflection path length of microwave energy are as follows:

[0080]

[0081] Using the two nonlinear functions mentioned above to represent the unknown parameters of water level By directly taking the first-order partial derivative, we obtain the Jacobian matrix composed of the antenna's absolute three-dimensional spatial coordinates:

[0082] The precise differential path length change obtained through multi-frequency unwinding in Example 4 Input this gradient calculation engine to perform a Taylor first-order inverse division solution (or iterative approximation). This will calculate the absolute height of the rise or fall of the true overall reservoir / river water level, after removing the malicious interference from independent local oscillators, beamcodebook constraints, and the influence of the x-coordinates of multiple reflection points. ; ultimately obtained as Figure 4 The water surface height phase trend comparison and error assessment chart shown below, from Figure 4As can be seen, the root mean square error (RMSE) of the water surface height is <0.05m, and the maximum absolute error of the water surface height is <0.1m.

[0083] This invention eliminates the need for pre-deploying any calibration objects on the water surface when performing water level inversion. The transmitting base station sends a reference signal via standard 5G protocol, and using the optimal precoding matrix indicator (PMI) fed back by the receiving base station, the elevation angle of the reflected beam on the water surface is directly obtained through beam codebook mapping. and Then, the initial Jacobian mapping matrix of the system is constructed using the extracted beam angles. This invention directly maps the microscopic changes in carrier phase to the vertical undulations of the macroscopic water surface. It should be noted that the real water surface is not an ideal mirror; it is subject to rough scattering due to wind and waves, and the transient scattering center deviates from the theoretical geometric reflection point. However, this invention utilizes the first Fresnel zone formed by the transmit and receive links for spatial energy integration, combined with long-term low-pass filtering of the differential phase, to effectively filter out high-frequency zero-mean wavefront tilt noise. The equivalent phase center after filtering is mathematically equivalent to the virtual mirror point position under a stable water surface; therefore, the solution has extremely high engineering practicality and commercial application value.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for measuring water surface rise and fall height based on cooperative 5G signals, characterized in that: The method includes: S1. Select several communication base stations around the water surface to be measured and establish a corresponding spatial reference model and beam codebook mapping table. S2. Select one base station and independently perform beam scanning mapping to the other base stations. Determine the corresponding optimal beam combination based on the dual reflection points and lock the independent effective scattering patches. S3. Based on the optimal wave velocity combination and the effective scattering plate, extract the reflection channel CSI from the OFDM sensing reference signal transmitted by the transmitting base station to the other receiving base stations, and extract the high-resolution carrier phase observation sequence of the center subcarrier and multiple edge subcarriers from it. S4. Perform multi-node phase differential operation on each extracted subcarrier frequency component. Through algebraic differential compensation operation, offset and cancel the independent local initial clock phase drift variables of all base stations to obtain a pure differential geometric phase sequence. S5. The obtained pure differential geometric phase value sequence is fed into an adaptive Kalman filter to dynamically track and separate the high-frequency phase jitter component caused by random water waves, and extract the stable phase envelope that reflects the trend evolution of the macro water level. S6. Based on subcarrier diversity, multi-frequency collaborative unwinding and dual-patch geometric inversion calculation are used to solve for the true vertical rise and fall height of the unified water surface, which is not affected by the difference in the horizontal coordinates of the reflecting surface.

2. The method for measuring water surface rise and fall height based on cooperative 5G signals according to claim 1, characterized in that: In step S1, three base stations are selected, with one base station designated as the transmitting node and the remaining base stations as receiving nodes; the corresponding phase center coordinates are established based on the locations of all base stations; and each precoding matrix indicator is established based on the transmitting and receiving beamcodebooks of the communication base stations. A mapping table showing the correspondence between the actual three-dimensional spatial physical two-dimensional angles.

3. The method for measuring water surface rise and fall height based on cooperative 5G signals according to claim 2, characterized in that: In step S2, the transmitting base station is controlled to perform independent beam scanning mapping to the two receiving base stations, and the different transmission links form two reflection points on the water surface, and the two reflection points are physically separated. Then, based on the received power or signal-to-noise ratio, a traversal scan is performed to evaluate and lock the optimal beam combination on different transmission links, denoted as follows: , and will , The spatial intersection area was determined as the first effective scattering patch and the second effective scattering patch on the water surface, where the subscript... Represents the transmitting base station, subscript These represent two receiving base stations.

4. The method for measuring water surface rise and fall height based on cooperative 5G signals according to claim 3, characterized in that: In step S3, the transmitting base station transmits OFDM broadband signals containing probe reference sequences to the other receiving base stations based on the locked optimal beam combination, and extracts the reflection channel CSI reflected from the corresponding effective scattering plate to the corresponding receiving base station; then, it extracts the frequency-specific signal from the reflection channel CSI. The center subcarrier and frequency are High-resolution CSI carrier phase sequence for specific edge subcarriers; Simultaneously, the base stations receive reference signals from each other using known directional beams for line-of-sight mutual transmission, and extract the carrier phase on the direct physical link.

5. The method for measuring water surface rise and fall height based on cooperative 5G signals according to claim 4, characterized in that: In step S4, multi-node phase differential operation is performed on each extracted subcarrier frequency component. Specifically, the reflected carrier phase of another receiving base station and the mutual direct signal carrier phase between the two receiving base stations are successively subtracted from the reflected carrier phase of one receiving base station to obtain a pure differential geometric phase sequence.

6. The method for measuring water surface rise and fall height based on cooperative 5G signals according to claim 5, characterized in that: In step S4, assume that the reflected carrier phase of one of the receiving base stations is in any subcarrier frequency The phase observation equation below is expressed as: In the formula, This represents the total electromagnetic wave propagation distance of the reflected link from transmitting base station A to receiving base station B at time t. This represents the initial random phase drift introduced by the independent local oscillator source of transmitting base station A. This represents the initial random phase drift introduced by the independent local oscillator source of the receiving base station B. This represents the phase integer ambiguity and residual noise term of the reflection link from transmitting base station A to receiving base station B; Suppose the phase of the reflected carrier of another receiving base station is in any subcarrier frequency The phase observation equation below is expressed as: In the formula, This represents the total electromagnetic wave propagation distance of the reflected link from transmitting base station A to receiving base station C at time t. This represents the initial random phase drift introduced by the independent local oscillator source at the receiving base station C. This represents the phase integer ambiguity and residual noise term of the reflection link from transmitting base station A to receiving base station C; Suppose that the carrier phase of the direct transmission signals between two receiving base stations is in any subcarrier frequency. The phase observation equation below is expressed as: In the formula, This represents the fixed linear distance between receiving base station B and receiving base station C. This represents the phase integer ambiguity and residual noise term of the direct link between receiving base station B and receiving base station C; Finally, the integrated differential phase parameters are constructed by measuring the nodes. After expansion and simplification, the equation finally converges to: in, This represents the residual combined integer ambiguity and the noise of the combined system. .

7. The method for measuring water surface rise and fall height based on cooperative 5G signals according to claim 5, characterized in that: In step S6, utilizing the stationary phase evolution characteristics of the center and edge frequency subcarriers, a multi-frequency cooperative unwinding equation is constructed through the "vernier effect" to directly recover the absolute change in the physical differential path length without jumps. Although the two reflective patches are separated from each other in horizontal position, they are both located on the same large-scale macroscopic water surface, that is, they share the same absolute altitude parameter. Then, the change in physical path length is substituted into the Jacobian partial derivative matrix composed of the three-dimensional coordinates of the base station. The partial derivative model based on the virtual image principle mathematically adaptively absorbs the different horizontal coordinates of the patch, and the overall vertical macroscopic rise and fall height of the real water surface is calculated in reverse through Taylor expansion.

8. The method for measuring water surface rise and fall height based on cooperative 5G signals according to claim 7, characterized in that: In step S6, the specific mathematical logic of the multi-frequency cooperative unwinding mechanism based on OFDM subcarrier diversity is as follows: Extraction frequency is and The pure differential phase sequence after dual-frequency subcarrier processing; Constructing the cooperative phase difference between two frequencies ; Based on the vernier effect, the equivalent large wavelength of dual-frequency co-synthetic synthesis is ; Without relying on the historical constraints of adjacent samples, the formula is used. It directly recovers the total absolute physical differential path change without jumps in a single snapshot.

9. A method for measuring water surface rise and fall height based on cooperative 5G signals according to claim 7, characterized in that: In step S6, the spatial geometric inversion solution mechanism for height variation under dual-patch separation is as follows: Based on the known antenna phase center coordinates , , Let the absolute elevation of the current macroscopic water surface to be measured be the plane. ; Based on the principle of the mirror virtual image method in three-dimensional space, the transmitting base station A is mapped as an equivalent virtual image source below the water surface. The coordinates are Regardless of the actual reflective patch... The equivalent absolute shortest propagation distance of electromagnetic waves along links AB and AC, depending on their location on the plane, is determined by the following nonlinear function: The total length of the differential path is: Using height parameters Taking the partial derivative of the change with respect to the total length of the differential path yields the Jacobian coefficient matrix, which reflects the spatial projection gradient relationship; when the change in the differential path is calculated... At that time, by using the inverse operation of the first-order linearized matrix, the true vertical rise and fall height of the uniform water surface, which is unaffected by the difference in the horizontal coordinates of the reflecting surface, can be solved. .

10. A system for implementing the water surface rise and fall height measurement method based on cooperative 5G signals as described in any one of claims 1-9, characterized in that: The system includes: Base station network and codebook management module: includes at least three communication base stations, maintains the 3GPP discrete beam codebook and performs spatial angle mapping; Independent Patch Tracking and Multi-Frequency CSI Extraction Module: Performs two-dimensional beam space traversal scanning, decouples and locks the two sets of optimal PMIs corresponding to two physically separated effective scattering patches on the water surface in a bistatic multi-receiver node environment, and extracts multi-subcarrier high-resolution carrier phase. Phase error elimination operation module: executes the core algorithm of multi-node three-element phase closed-loop differential logic, and uses mutual direct signals to completely offset and cancel the clock drift error caused by the independent local oscillator source of each base station; Multi-frequency unwinding and dual-patch geometric inversion module: It integrates OFDM subcarrier vernier effect to directly recover absolute path increment, combines adaptive Kalman filtering to suppress high-frequency clutter, and uses virtual image Jacobian matrix to inversely map the micro-path change containing information of two different spatial reflection points into a unified physical vertical macro-reservoir water level height.

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