A method for modeling multipath signal error considering obstacle influence

Abstract

The application relates to a multipath signal error modeling method considering the influence of obstacles. The method comprises the following steps: calculating the shielding condition of a direct path between each transmitting source and a receiver, and if the direct path exists, calculating the related information of the arrival power and phase delay corresponding to the direct path. The 1th to nth order reflection paths of each transmitting source are recursively solved until the arrival power of the nth order reflection path is less than a receiving threshold, and the related information of the arrival power and phase delay corresponding to all the reflection paths is calculated. The 1th to mth order diffraction paths of each transmitting source are recursively solved until the arrival power of the mth order diffraction path is less than a receiving threshold, and the related information of the arrival power and phase delay corresponding to all the diffraction paths is calculated. According to the order of the transmitting source-intermediate point-receiver, each reflection path or diffraction path is connected to construct a multipath signal model. The method can improve the receiver performance and positioning accuracy.

Description

Technical Field

[0001] This application relates to the field of signal multipath technology, and in particular to a multipath signal error modeling method that takes into account the influence of obstacles. Background Technology

[0002] When the receiver is located in an open area with no obstructions, it is less affected by multipath interference, and generally only the direct signal needs to be considered. However, when the receiver is located in a built-up area, the signal propagates through buildings such as towers. Due to electromagnetic wave reflection and diffraction, in addition to the direct signal, there may be multiple multipath signals consisting of reflected and diffracted signals reaching the receiver. These multipath signals will affect the receiver's carrier-to-noise ratio, thus significantly impacting positioning accuracy; in some cases, there may even be no direct signal, only multipath signals.

[0003] In urban scenarios, multipath signals can have a significant impact on positioning accuracy. To accurately predict the number of multipath signals, transmission delay, and path loss in a given scenario, it is necessary to model and analyze the impact of multipath signals and then adopt corresponding countermeasures to improve receiver performance. Summary of the Invention

[0004] Therefore, it is necessary to provide a multipath signal error modeling method that takes into account the influence of obstacles, which can improve receiver performance and positioning accuracy, in order to address the above-mentioned technical problems.

[0005] A method for modeling multipath signal errors that takes into account the influence of obstacles, the method comprising:

[0006] A city environment model of buildings and ground is constructed based on the 3D images of the analyzed scene.

[0007] Determine the number of satellite and non-satellite sources included in the launch source and their corresponding configuration information.

[0008] Calculate the obstruction of the direct path from each transmitter to the receiver by urban buildings, determine whether a direct path exists, and if so, calculate the relevant information of the arrival power and phase delay corresponding to the direct path.

[0009] For each transmitter, recursively solve for its first to nth order reflection paths until the arrival power of the nth order reflection path is less than the receiver's reception threshold, and calculate the relevant information of arrival power and phase delay for all reflection paths.

[0010] For each transmitter, recursively solve for its diffraction paths from order 1 to order m until the arrival power of the m-th diffraction path is less than the receiver's reception threshold, and calculate the relevant information of arrival power and phase delay for all diffraction paths.

[0011] The total arriving power of all reflected paths, the total arriving power of diffracted paths, and the total direct power of all non-satellite sources are statistically analyzed and then superimposed on the environmental noise to form the total noise power of the multipath signal model.

[0012] The carrier-to-noise ratio is calculated based on the direct power of each satellite source and the total noise power of the multipath signal model. Based on the carrier-to-noise ratio, the total noise power of the multipath signal model, the relevant information corresponding to the reflection path, and the relevant information corresponding to the diffraction path, each reflection path or diffraction path is connected in the order of transmitter-intermediate point-receiver to construct a multipath signal model.

[0013] The aforementioned multipath signal error modeling method that considers the influence of obstacles first constructs an environmental model of urban buildings and the ground based on 3D images, transforming the distribution of obstacles in the real scene into a computable geometric structure, providing a precise physical carrier for multipath signal analysis. Setting the positions, transmission gains, and power of both satellite and non-satellite sources, as well as the position, receiving gain, and receiving threshold of the receiver, and environmental noise power, provides the model with a rich and realistic scenario. Second, through a common visible surface traversal mechanism of the transmitter and receiver points, combined with an intersection judgment algorithm for direct paths, accurate identification of direct signals is achieved. When the direct path is blocked by obstacles, a ray-back tracing algorithm is used to calculate the reflection path. Unlike traditional algorithms that pre-set the reflection order, this method adaptively adjusts the reflection order by setting the receiver's receiving threshold, accurately calculating the effective reflection path while ensuring computational efficiency and avoiding omissions and over-calculations. Furthermore, for diffraction path calculation, an effective diffraction point extraction method based on visible wedges is adopted to calculate the diffraction path. Simultaneously, an adaptive diffraction order determination method based on the receiving threshold is introduced, solving the problem of the enormous computational load of diffraction points in practical scenarios, balancing computational efficiency and effectiveness. Next, the arrival power of all reflection paths, diffraction paths, and non-satellite source direct power are integrated and superimposed on the noise power to form the total noise power of the model. The carrier-to-noise ratio is calculated using the satellite source direct power and the total noise power. Finally, in the 3D city model, the arrival power, phase delay, attenuation, incident angle, and reflection angle of the direct, reflection, and diffraction paths, as well as the carrier-to-noise ratio, are visually displayed in ray form, constructing a multipath signal error model to provide the receiver with a quantitative basis for multipath interference. This model can handle multipath superposition interference when direct signals are present, and can also infer the target position through the phase characteristics of multipath signals in extreme scenarios without direct signals, transforming multipath effects from a source of positioning error into usable positioning information, ultimately achieving a significant improvement in positioning accuracy. Attached Figure Description

[0014] Figure 1 A flowchart of a multipath signal error modeling method that takes into account the influence of obstacles in one embodiment;

[0015] Figure 2 A flowchart of a multipath signal error modeling step that takes into account the influence of obstacles in one embodiment;

[0016] Figure 3 This is an example of the execution process of a multipath signal error modeling method that takes into account the influence of obstacles in one embodiment; Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0018] In one embodiment, such as Figure 1 As shown, a multipath signal error modeling method that takes into account the influence of obstacles is provided, including the following steps:

[0019] Step 102: Construct an urban environment model of city buildings and ground based on the 3D images of the analyzed scene.

[0020] Specifically, based on the 3D image of the determined analysis scene, modeling software is used to construct the vertex coordinates of all triangular faces of urban buildings and the ground, as well as the connection relationships of the triangular faces, to obtain an urban environment model.

[0021] Furthermore, the transmission-related information includes: transmitter coordinates, transmission power, and transmitter gain. The reception-related information includes: receiver coordinates and receiver gain. Transforming the transmitter coordinates and receiver coordinates to the station-centered coordinate system using a coordinate transformation matrix yields the standard position coordinates:

[0022] ;

[0023] in, The standard position coordinates of the satellite, The coordinates of the satellite's position in the Earth-centered, Earth-fixed rectangular coordinate system. The coordinates of the city's central location;

[0024] This is the coordinate transformation matrix. and These are the longitude and latitude of the city's environmental center, respectively.

[0025] Step 104: Determine the number of satellite sources and non-satellite sources included in the transmission source and their corresponding settings.

[0026] Specifically, determine the number of satellite and non-satellite sources included in the transmission source, the corresponding locations, power, and transmission gain of the satellite and non-satellite sources, and set the receiver's location, receiving gain, receiving threshold, and ambient noise power.

[0027] Furthermore, for signal transmission along the reflection path, the reflected power is calculated. The reflected power is calculated for each reflection path separately. Based on the complex permittivity of the reflecting surface, the reflection coefficient at the reflection point is obtained. The attenuation of all reflection orders is accumulated to obtain the reflected power and phase delay for each path, including:

[0028] In ray-based coordinates, the vertical and horizontal polarization components of the reflected field are as follows:

[0029] ;

[0030] These are the vertical and horizontal polarization components of the reflected final field; Assuming the incident wave is perpendicular to the reflection point, The amplitude diffusion factor, For phase accumulation, and These are the reflection coefficients for parallel and vertically polarized waves, respectively. and The refractive indices for parallel and perpendicular polarized waves can be obtained using Fresnel's formula:

[0031] ;

[0032] ;

[0033] in, Angle of incidence and are the complex permittivity of air and the reflector material, respectively.

[0034] Furthermore, for signal transmission along the diffraction path, the calculation of diffraction power and phase delay includes: decomposing the final field electric vectors of the incident wave and the final field electric vectors of the diffracted wave into parallel components in the aforementioned coordinate system. , With vertical component , Then the relationship between the final field of the incident wave and the field strength of the diffracted wave at the receiving point R is expressed by the following equation:

[0035] ;

[0036] in, Let be the diffusion coefficient of the diffracted wave from the diffraction point D to the receiving point R. When it is a spherical wave, , The distance between the emission point and the reflection point. The distance between the reflecting point and the receiving point; The cumulative phase of the diffracted wave from the diffraction point D to the receiving point R; is the diffraction coefficient in the ray-based coordinate system.

[0037] Furthermore, and These are the diffraction coefficients for parallel and vertically polarized waves, respectively. To date, the calculation of diffraction coefficients in diffraction theory research has been mainly divided into two categories: ideal conductive wedges and finite conductivity dielectric wedges. This embodiment adopts the finite conductivity dielectric wedge calculation method.

[0038] Step 106: Calculate the obstruction of the direct path between each transmitter and receiver by urban buildings, determine whether a direct path exists, and if so, calculate the relevant information of arrival power and phase delay corresponding to the direct path.

[0039] Specifically, iterate through all common visible surfaces. Based on the intersection relationship between the line connecting the transmitter and receiver and the common visible surfaces, if the line is parallel to all common visible surfaces, the intersection relationship is non-intersecting; if the line is not parallel to the common visible surfaces and the common visible surfaces are in the negative direction of the line, the intersection relationship is non-intersecting; if the line is not parallel to the common visible surfaces and the common visible surfaces are in the positive direction of the line, the intersection relationship is intersecting; if the intersection relationship of all common visible surfaces is non-intersecting, then calculate the direct path.

[0040] Furthermore, based on the propagation loss of multipath signals on the direct path, the arrival power at the receiving point is calculated using Fries' formula:

[0041] ;

[0042] in, Input power to the transmitting antenna, For the transmit antenna gain, The distance between the field point and the source point. Let the incident wave energy flux density be... For the effective area of ​​the receiving antenna, For receiving antenna gain, The wavelength is in free space. The phase delay of the received signal is obtained based on the power at the receiving point and the receiver gain.

[0043] Step 108: For each transmitter, recursively solve for its first to nth order reflection paths until the arrival power of the nth order reflection path is less than the receiver's reception threshold, and calculate the relevant information of arrival power and phase delay for all reflection paths.

[0044] Specifically, the first-order mirror point is calculated based on the visible surface of the transmitter. Connecting this first-order mirror point to the receiving point yields a first-order mirror line. The intersection of this first-order mirror line with the visible surface of the transmitter and its extended surface is calculated to obtain the reflection point. It is determined whether the reflection point is within the visible surface of the transmitter and whether it is located in the middle of the first-order mirror line, thus identifying the first-order reflection point. Based on the lines connecting the first-order reflection point to the transmitter and receiving points, it is determined whether these lines intersect with all planes except the current reflecting surface, and the reflection path is calculated.

[0045] Furthermore, if the first line connecting the transmitter and the first-order reflection point intersects all planes except the current reflection surface, or the second line connecting the first-order reflection point and the receiver intersects all planes except the current reflection surface, then the reflection path is blocked; if the first line does not intersect all planes except the current reflection surface, and the second line does not intersect all planes except the current reflection surface, then the reflection path is valid, and the reflection path is calculated.

[0046] Furthermore, based on the complex dielectric constant of the current reflecting surface, the reflection coefficient at the reflecting point is calculated:

[0047] ;

[0048] ;

[0049] in, and These are the reflection coefficients for parallel and vertically polarized waves, respectively. Angle of incidence and Let be the complex permittivity of air and the reflector material, respectively. Based on the reflection coefficient, the reflection power and phase delay of each reflection path are obtained by accumulating the reflection attenuation of all orders.

[0050] Step 110: For each transmitter, recursively solve for its diffraction paths from order 1 to m until the arrival power of the m-th diffraction path is less than the receiver's reception threshold, and calculate the relevant information of arrival power and phase delay for all diffraction paths.

[0051] Specifically, the visible wedge corresponding to the visible surface of each transmitting source is solved to obtain several diffraction points. If a diffraction point lies on a finite wedge, it is a valid diffraction point. If the first diffraction line connecting the transmitting source and the valid diffraction point intersects all visible surfaces, or the second diffraction line connecting the valid diffraction point and the receiving point intersects all visible surfaces, then there is an obstacle blocking the diffraction path, and the diffraction path is invalid. If the first diffraction line intersects but does not intersect with all visible surfaces, and the second diffraction line does not intersect with all visible surfaces, then the diffraction path is valid, and the diffraction path is calculated.

[0052] Step 112: Calculate the total arriving power of all order reflection paths, the total arriving power of diffraction paths, and the total direct power of all non-satellite sources, and then superimpose them into the environmental noise as the total noise power of the multipath signal model.

[0053] Step 114: Calculate the total arriving power of all order reflection paths, the total arriving power of diffraction paths, and the total direct power of all non-satellite sources, and then superimpose them into the environmental noise as the total noise power of the multipath signal model.

[0054] Step 116: Calculate the carrier-to-noise ratio based on the direct power of each satellite source and the total noise power of the multipath signal model. Based on the carrier-to-noise ratio, the total noise power of the multipath signal model, the relevant information corresponding to the reflection path, and the relevant information corresponding to the diffraction path, connect each reflection path or diffraction path in the order of transmitter-intermediate point-receiver to construct the multipath signal model.

[0055] In one embodiment, such as Figure 2 As shown, a multipath signal error modeling step that takes into account the influence of obstacles is provided, and the execution process is as follows: Figure 3 As shown, the specific content is as follows:

[0056] Step 1: Construct an urban environment model of city buildings and ground using triangular facets based on the 3D image.

[0057] Specifically, 3D image modeling software is used to construct the vertex coordinates and connection relationships of all triangular faces of urban buildings and the ground, thus obtaining an urban environment model.

[0058] Step 2: Set the receiver's location, gain, reception threshold, and ambient noise power; distinguish between satellite and non-satellite sources, and set the number, type, location, power, gain, and other parameters of the sources.

[0059] Specifically, a receiver is placed at a certain location between buildings in the 3D city, with a receiving gain of [value missing]. The receiving threshold is The ambient noise power is Several satellite and non-satellite sources are set up as transmission sources. The non-satellite sources are close to the receiver, at a low altitude, and have a transmission power of [missing information]. The transmit gain is .

[0060] Step 3: Calculate the interference blockage between each transmitter and receiver, determine whether there is a direct path, and if so, calculate the arrival power and phase delay.

[0061] Specifically, first, the coordinates of the transmitter and receiver are transformed to the station-centric coordinate system, and then each transmitter and receiver is connected by a line, i.e., tx-rx. Next, each triangular facet of the city building model is traversed to determine whether it intersects with tx-rx. If it intersects, there is no direct path; if it does not intersect, there is a direct path.

[0062] Furthermore, if a direct path exists, the direct power is calculated using the following formula:

[0063] ;

[0064] in, Input power to the transmitting antenna ( ), For the transmit antenna gain, The distance between the field point and the source point ( ), incident wave energy flux density , Effective area of ​​the receiving antenna , For receiving antenna gain, free space wavelength ( The phase delay of the received signal is obtained based on the power of the receiving point and the receiver gain.

[0065] Step 4: For each transmitter, recursively solve for its first to nth order reflection paths until the power of the nth order reflection path reaching the receiver is less than the receiving threshold; calculate the power and phase delay of all reflection paths.

[0066] Specifically, the i-th order reflection path is calculated using the reverse ray tracing method. Start from 1.

[0067] (1) Calculate the i-th order reflection path, record the reflection point, emission angle, and incident angle, and calculate the arriving power. .

[0068] (2) Determine the power reached The size of the receiver threshold, if Then set Treat the i-th order mirror point as the new emission point and repeat (1); if If so, then jump to (3).

[0069] (3) Record all the order reflection paths generated by (1) and (2), and calculate the arrival power, phase delay, reflection point, signal attenuation and other information for each reflection path.

[0070] Step 5: For each transmitter, recursively solve for its diffraction paths from order 1 to order m until the power of the (m-1)th diffraction path reaching the receiver is less than the receiving threshold; calculate the power and phase delay of all diffraction paths.

[0071] Specifically, an effective diffraction point extraction method based on visible wedges is used to calculate the diffraction path, while the diffraction order is adaptively adjusted in conjunction with the receiver's reception threshold. The specific operation is similar to step 4.

[0072] An effective diffraction point extraction method based on visible wedges is adopted to calculate the diffraction path, and the diffraction order is adaptively adjusted in combination with the receiver reception threshold.

[0073] (1) Calculate the first The first reflection path is recorded, the diffraction point is recorded, and the arrival power is calculated. .

[0074] (2) Determine the power reached The size of the receiver threshold, if Then set Repeat (1); if If so, then jump to (3).

[0075] (3) Record all diffraction paths generated by (1) and (2), and calculate the arrival power, phase delay, diffraction point, signal attenuation and other information for each diffraction path.

[0076] Step 6: Calculate the total power of all reflection paths and diffraction paths, as well as the direct power of all non-satellite sources, and add them to the environmental noise power to obtain the total noise of the model; the direct power of each satellite source is the signal power, and the carrier-to-noise ratio is calculated.

[0077] Specifically, first, the total noise power of the multipath signal model is calculated using the following formula:

[0078] ;

[0079] The four terms on the right side of the equation are the power arriving through all reflection paths, the power arriving through all diffraction paths, the power arriving directly through all non-satellite sources, and the power of ambient noise, respectively.

[0080] Assume that the power of one of the satellite sources reaching the receiver is Then the carrier-to-noise ratio is;

[0081]

[0082] Step 7: Connect the transmitter-reflection point-receiver and the transmitter-diffraction point-receiver to display all paths and their corresponding arrival power, as well as the final carrier-to-noise ratio, in the 3D city building model; construct a multipath signal model.

[0083] Specifically, each path is connected in sequence, and the paths are displayed using rays in the 3D city scene. The arrival power, loss, phase delay, emission angle and incident angle of each path are also displayed. For direct paths from satellite sources, the equivalent carrier-to-noise ratio is displayed.

[0084] In one embodiment, based on the 3D image of the determined analysis scene, modeling software is used to construct the vertex coordinates of all triangular faces of urban buildings and the connection relationships of the triangular faces, thereby obtaining an urban environment model.

[0085] In one embodiment, the configuration information includes: the location, power, and transmit gain of the satellite source and non-satellite sources. The receiver's location, receive gain, receive threshold, and ambient noise power are also configured.

[0086] In one embodiment, to distinguish whether the transmitting source is a satellite source or a non-satellite source, a receiver is placed at a certain location among the buildings in the three-dimensional city, with a receiving gain of [value missing]. The receiving threshold is The ambient noise power is Several satellite and non-satellite sources are set up as transmission sources. The non-satellite sources are placed on the Earth's surface or in near-Earth space. The distance between the receiver and the non-satellite source is much smaller than the distance between the receiver and the satellite source. The satellite source is at an altitude of over 100 kilometers, and the transmission power is [missing information]. The transmit gain is .

[0087] In one embodiment, the coordinates of the transmitter and receiver are first transformed to the station-centric coordinate system. After connecting each transmitter and receiver, a transmission-receiver straight line is obtained. Each triangular facet of the city building model is traversed to determine whether it intersects with the transmission-receiver straight line. If they intersect, there is no direct path; otherwise, a direct path exists. The arrival power is then calculated.

[0088] ;

[0089] in, Input power to the transmitting antenna ( ), For the transmit antenna gain, The distance between the field point and the source point ( ), incident wave energy flux density , For the effective area of ​​the receiving antenna ( ), For receiving antenna gain, free space wavelength ( The phase delay of the received signal is obtained based on the arriving power and receiver gain, and relevant information about the transmission angle and incident angle is calculated.

[0090] In one embodiment, the reverse ray tracing method is used to calculate the arrival power of the current order reflection path based on the visible surface corresponding to the emission source. The arrival power is then compared with the receiver threshold. If the arrival power is greater than the receiver threshold, the mirror point of the current order emission source is used as the emission point of the next order, and the arrival power of the next order emission point is calculated again until the arrival power is not greater than the receiver threshold. The reflection point, arrival power, phase delay, emission angle, and incident angle of all reflection paths from order 1 to n-1 are recorded.

[0091] In one embodiment, an effective diffraction point extraction method based on visible wedges is used to adaptively adjust the diffraction order according to the receiver's reception threshold. The arrival power of each transmitter corresponding to the current diffraction path is calculated, and the arrival power is compared to the receiver threshold. If the arrival power is not greater than the receiver threshold, the diffraction point, arrival power, phase delay, transmission angle, and incident angle of the current and next order diffraction paths are recorded. Otherwise, the arrival power of the next order diffraction path is calculated. This process continues until the arrival power of the m-th order diffraction path is less than the receiver's reception threshold, recording the diffraction point, arrival power, phase delay, transmission angle, and incident angle of all diffraction paths from order 1 to m-1.

[0092] In one embodiment, the total arriving power of all order of reflection paths, the total arriving power of diffracted paths, and the total direct power of all non-satellite sources are statistically analyzed and then superimposed on the ambient noise to calculate the total noise power of the multipath signal model.

[0093] ;

[0094] in, This represents the total noise power. The total arriving power across all reflection paths, The total arriving power across all diffracted paths, For the direct power of all non-satellite sources, This represents the power of environmental noise.

[0095] In one embodiment, based on the direct power of each satellite source The total noise power of the multipath signal model is used to calculate the carrier-to-noise ratio:

[0096] ;

[0097] in, For the direct power of the satellite source, denoted as the total noise power of the multipath signal model, and CNR as the carrier-to-noise ratio.

[0098] In one embodiment, the carrier-to-noise ratio (CNR) is calculated based on the direct power of each satellite source and the total noise power of the multipath signal model. Based on the CNR, the total noise power of the multipath signal model, relevant information corresponding to the reflection path, and relevant information corresponding to the diffraction path, each reflection path or diffraction path is connected in the order of transmitter-reflection point-receiver or transmitter-diffraction point-receiver. Rays are used to display the paths in the three-dimensional urban scene of the urban environment model, and the arrival power, loss, phase delay, emission angle, and incident angle of each path, as well as the direct path of the satellite source and the CNR, are displayed to complete the construction of the multipath signal model.

[0099] It should be understood that, although Figures 1-3 The steps in the flowchart are shown sequentially as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order in which these steps are executed, and they can be performed in other orders. Figures 1-3 At least some of the steps in the process may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least some of the sub-steps or stages of other steps.

[0100] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided by this invention can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0101] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0102] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A method for modeling multipath signal errors that takes into account the influence of obstacles, characterized in that, The method includes: A city environment model of buildings and ground is constructed based on the 3D images of the analyzed scene. Determine the number of satellite and non-satellite sources included in the launch source and their corresponding configuration information; Calculate the obstruction of the direct path from each transmitter to the receiver by urban buildings, determine whether a direct path exists, and if so, calculate the relevant information of the arrival power and phase delay corresponding to the direct path. For each of the transmitting sources, its first to nth order reflection paths are recursively solved until the arrival power of the nth order reflection path is less than the receiver's reception threshold, and the relevant information of arrival power and phase delay for all the reflection paths is calculated. For each of the transmitting sources, recursively solve for its diffraction paths from order 1 to m until the arrival power of the m-th diffraction path is less than the receiving threshold of the receiver, and calculate the relevant information of arrival power and phase delay for all the diffraction paths. The total arriving power of the reflection paths of all orders, the total arriving power of the diffraction paths, and the total direct power of all non-satellite sources are summed and added to the environmental noise to form the total noise power of the multipath signal model. The carrier-to-noise ratio is calculated based on the direct power of each satellite source and the total noise power of the multipath signal model. Based on the carrier-to-noise ratio, the total noise power of the multipath signal model, the relevant information corresponding to the reflection path, and the relevant information corresponding to the diffraction path, each reflection path or diffraction path is connected in the order of transmitter-intermediate point-receiver to construct a multipath signal model.

2. The method according to claim 1, characterized in that, Based on the 3D images of the analyzed scene, an urban environment model of the city's buildings and ground is constructed, including: Based on the 3D image of the determined analysis scene, modeling software is used to construct the vertex coordinates of all triangular faces of urban buildings and the ground, as well as the connection relationships of the triangular faces, to obtain an urban environment model.

3. The method according to any one of claims 1 to 2, characterized in that, The configuration information includes: the location, power, and transmission gain of the satellite source and non-satellite sources; Set the receiver's location, receiver gain, receiver threshold, and ambient noise power.

4. The method according to claim 3, characterized in that, Determine the number of satellite and non-satellite sources included in the transmission source and their corresponding configuration information, including: To distinguish between satellite and non-satellite sources, a receiver is placed at a location between buildings in a 3D city, with a receiving gain of [value missing]. The receiving threshold is The ambient noise power is Several satellite and non-satellite sources are set up as transmission sources. The non-satellite sources are placed on the Earth's surface or in near-Earth space. The distance between the receiver and the non-satellite source is much smaller than the distance between the receiver and the satellite source. The satellite source is at an altitude of over 100 kilometers, and the transmission power is [missing information]. The transmit gain is .

5. The method according to claim 4, characterized in that, Calculate the obstruction of the direct path from each transmitter to the receiver by urban buildings to determine if a direct path exists. If so, calculate the relevant information regarding the arrival power and phase delay corresponding to the direct path, including: First, convert the coordinates of the transmitter and receiver to the station center coordinate system, and then connect each transmitter and receiver to obtain the transmitter-receiver line; Iterate through each triangular facet of the city building model, determining whether the facet intersects with the connecting line. If they intersect, there is no direct path; otherwise, there is a direct path. Calculate the arrival power. ； in, Input power to the transmitting antenna, For the transmit antenna gain, The distance between the field point and the source point. Let the incident wave energy flux density be... For the effective area of ​​the receiving antenna, For receiving antenna gain, Wavelength in free space; The phase delay of the received signal is obtained based on the arrival power and receiver gain, and relevant information about the transmission angle and incident angle is calculated.

6. The method according to claim 4, characterized in that, For each of the transmitting sources, its first to nth order reflection paths are recursively solved until the arrival power of the nth order reflection path is less than the receiver's reception threshold. Relevant information regarding the arrival power and phase delay for all the reflection paths is then calculated, including: The inverse ray tracing method is used to calculate the arrival power of the current order reflection path based on the visible surface corresponding to the emission source. The arrival power is compared with the receiver threshold. If the arrival power is greater than the receiver threshold, the mirror point of the current order emission source is used as the emission point of the next order, and the arrival power of the next order emission point is calculated again until the arrival power of the nth order reflection path is not greater than the receiver threshold. The reflection point, arrival power, phase delay, emission angle, and incident angle of all reflection paths from order 1 to n-1 are recorded.

7. The method according to claim 4, characterized in that, For each of the transmitting sources, its diffraction paths from order 1 to m are recursively solved until the arrival power of the m-th diffraction path is less than the receiver's reception threshold. Relevant information regarding the arrival power and phase delay for all the diffraction paths is then calculated, including: An effective diffraction point extraction method based on visible wedges is adopted to adaptively adjust the diffraction order according to the receiver's reception threshold. The arrival power of each transmitter corresponding to the current diffraction path is calculated, and the arrival power is compared with the receiver threshold. If the arrival power is not greater than the receiver threshold, the diffraction point, arrival power, phase delay, transmission angle, and incident angle of the current and next order diffraction paths are recorded. Otherwise, the arrival power of the next order diffraction path is calculated. This process continues until the arrival power of the m-th order diffraction path is less than the receiver's reception threshold. The diffraction point, arrival power, phase delay, transmission angle, and incident angle of all diffraction paths from order 1 to m-1 are recorded.

8. The method according to claim 7, characterized in that, The total arriving power of the reflection paths of all orders, the total arriving power of the diffracted paths, and the total direct power of all non-satellite sources are summed and added to the environmental noise to form the total noise power of the multipath signal model, including: The total arriving power of the reflection paths of all orders, the total arriving power of the diffracted paths, and the total direct power of all non-satellite sources are summed and added to the ambient noise to calculate the total noise power of the multipath signal model. ； in, This represents the total noise power. The total arriving power across all reflection paths, The total arriving power across all diffracted paths, For the direct power of all non-satellite sources, This represents the power of environmental noise.

9. The method according to claim 8, characterized in that, The carrier-to-noise ratio is calculated based on the direct power of each satellite source and the total noise power of the multipath signal model, including: Based on the direct power of each of the satellite sources The total noise power of the multipath signal model is used to calculate the carrier-to-noise ratio: ； in, For the direct power of the satellite source, denoted as the total noise power of the multipath signal model, and CNR as the carrier-to-noise ratio.

10. The method according to claim 9, characterized in that, The carrier-to-noise ratio (CNR) is calculated based on the direct power of each satellite source and the total noise power of the multipath signal model. Then, based on the CNR, the total noise power of the multipath signal model, relevant information corresponding to the reflection path, and relevant information corresponding to the diffraction path, each reflection path or diffraction path is connected in the order of transmitter-intermediate point-receiver to construct a multipath signal model, including: The carrier-to-noise ratio (CNR) is calculated based on the direct power of each satellite source and the total noise power of the multipath signal model. Then, based on the CNR, the total noise power of the multipath signal model, relevant information corresponding to the reflection path, and relevant information corresponding to the diffraction path, each reflection path or diffraction path is connected in the order of transmitter-reflection point-receiver or transmitter-diffraction point-receiver. Rays are used to display the paths in a 3D urban scene of the urban environment model, and the arrival power, loss, phase delay, emission angle, and incident angle of each path, as well as the direct path of the satellite source and the CNR, are displayed, thus completing the construction of the multipath signal model.

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