A Fast Ray Tracing Method and Device Suitable for Channel Modeling in Urban Scenarios

Abstract

The present invention provides a fast ray tracing method and apparatus applicable to urban scene channel modeling. The steps of the method include: dividing regions in the top view plane of a three-dimensional urban model; each time a ray is emitted from an emission position, determining whether it enters a signal receiving point based on the emission position and emission direction of the ray; if the ray does not enter the signal receiving point, determining whether the ray intersects with the obstacle model in the region where the emission position is located after being emitted from the emission position based on the emission position and emission direction of the ray; if there is an intersection, obtaining the obstacle surface where the ray intersects with the obstacle model and emitting again; if there is no intersection, determining the region where the ray intersects based on the emission position and emission direction of the ray, obtaining the obstacle surface where the ray intersects with the obstacle model, and emitting again; if the ray enters the signal receiving point, obtaining the propagation paths of all the rays that enter the signal receiving point from the signal emission point to the signal receiving point.

Description

Technical Field

[0001] The present invention relates to the field of communication technologies, and in particular, to a fast ray tracing method and device suitable for channel modeling in urban scenarios. Background Art

[0002] The fifth-generation (5G) communication is expected to support a variety of scenarios and applications, including but not limited to enhanced mobile broadband (eMBB), ultra-reliable low-latency communication (URLLC), and massive machine-type communication (mMTC), and new network architectures have been proposed for various applications. To effectively support the design, deployment, and evaluation of 5G and above wireless communication technologies, accurate channel characteristics and modeling are crucial.

[0003] Channel modeling methods can be divided into statistical channel models and deterministic channel models. Statistical channel models are a summary and analysis of measured data in terms of statistical distributions, with wide applicability but low accuracy in specific scenarios. Deterministic channel models are commonly used in specific scenarios and have high accuracy for their specific scenarios. Among them, the ray tracing method is one of the most representative methods. Its basic idea is to simulate radio wave propagation through the interaction process of different rays with the scenario. These rays propagate from the transmitting antenna to the receiving antenna and are reflected, scattered, and diffracted by the walls and edges of buildings, walls, and similar obstacles. Calculations are performed using geometric optics (GO) and uniform theory of diffraction (UTD), and then channel parameters such as time delay and power are obtained.

[0004] However, the most time-consuming part in channel modeling based on this method is to search for all effective paths from the transmitter to the receiver. Each calculation in the prior art needs to cover the entire scenario, and the calculation time is highly correlated with the complexity of the scenario. If a complex scenario is encountered, the calculation amount is huge. Summary of the Invention

[0005] In view of this, embodiments of the present invention provide a fast ray tracing method suitable for channel modeling in urban scenarios to eliminate or improve one or more defects existing in the prior art.

[0006] One aspect of the present invention provides a fast ray tracing method suitable for channel modeling in urban scenarios, and the steps of the method include:

[0007] Receiving a pre-constructed three-dimensional urban model, setting a signal transmission point and a signal reception point in the three-dimensional urban model, where the three-dimensional urban model includes a plurality of obstacle models, and each obstacle model includes a plurality of obstacle surfaces;

[0008] Dividing regions in the top view plane of the three-dimensional urban model, marking the regions where each of the obstacle models is located, and marking the regions where each obstacle surface is located;

[0009] After each emission, based on the emission position and emission direction of the ray, perform the step of determining whether the ray enters the signal receiving point. The ray is used to simulate a signal, and the emission position is an obstacle surface or a signal emission point;

[0010] If the ray does not enter the signal receiving point, based on the emission position and emission direction of the ray, determine whether the ray intersects with the obstacle model in the area where the emission position is located after being emitted from the emission position;

[0011] If there is an intersection, obtain the obstacle surface where the ray intersects with the obstacle model, re-determine the emission position and emission direction of the ray, and perform the step of determining whether the ray enters the signal receiving point;

[0012] If there is no intersection, based on the emission position and emission direction of the ray, determine whether the ray intersects with the obstacle surface of the obstacle model after leaving the area where the emission position is located; if so, re-determine the emission position and emission direction of the ray, and perform the step of determining whether the ray enters the signal receiving point; if not, determine that the ray exits the three-dimensional city model;

[0013] If the ray enters the signal receiving point, obtain the propagation paths of all the rays entering the signal receiving point from the signal emission point to the signal receiving point.

[0014] Adopting the above solution, first, this solution divides the three-dimensional city model into multiple regions in the top view plane. In the calculation of each propagation route, it can start from the area where the emission position is located. If the ray does not intersect with the obstacle model in the area where the emission position is located, further determine the area where the ray intersects, and perform the calculation in the intersecting area. Each time, only one area needs to be calculated, and there is no need to calculate the entire scene, optimizing the calculation efficiency.

[0015] In some embodiments of the present invention, the step of receiving the pre-constructed three-dimensional city model further includes marking the area where the obstacle surface is located, and based on the visibility relationship between the obstacle surfaces, obtaining all the obstacle surfaces that have a visibility relationship with each obstacle surface.

[0016] In some embodiments of the present invention, in the step of determining whether the ray intersects with the obstacle model in the area where the emission position is located after being emitted from the emission position based on the emission position and emission direction of the ray, if the emission position is an obstacle surface, determine whether the ray intersects with the obstacle surface that has a visibility relationship with the obstacle surface at the emission position within the area of the obstacle surface at the emission position;

[0017] In the step of determining whether the ray intersects with the obstacle surface of the obstacle model after leaving the area where the emission position is located, if the emission position is an obstacle surface, determine whether the ray intersects with the obstacle surface that has a visibility relationship with the obstacle surface at the emission position in other areas except the emission area.

[0018] With the above solution, the present application pre-obtains the visibility relationship between the obstacle surfaces. In the calculation of each area, only the visible surfaces of the obstacle surfaces that emit rays need to be calculated, further improving the calculation efficiency.

[0019] In some embodiments of the present invention, the step of obtaining all the obstacle surfaces that have a visibility relationship with each obstacle surface based on the visibility relationship between the obstacle surfaces includes:

[0020] Number the obstacle surfaces;

[0021] Based on the visibility relationship of each obstacle surface, establish a look-up table, and store the labels of all the obstacle surfaces that have a visibility relationship with this obstacle surface in the look-up table.

[0022] In some embodiments of the present invention, the obstacle surface includes a planar region and an edge region corresponding to each edge of the obstacle surface. The step of, if there is an intersection, obtaining the obstacle surface where the ray intersects the obstacle model, determining the emission position and emission direction of the ray again, and performing the step of determining whether to shoot into the signal receiving point includes:

[0023] If the ray intersects the obstacle surface in the planar region, it is determined that reflection occurs, and the emission angle is determined based on the incident angle incident on the planar region to obtain the emission direction;

[0024] If the ray intersects the obstacle surface in the edge region, it is determined that diffraction occurs, and the emission direction is obtained based on the uniform geometrical diffraction theory.

[0025] In some embodiments of the present invention, the step of establishing a look-up table based on each obstacle surface and storing all the obstacle surfaces that have a visibility relationship with this obstacle surface in the look-up table includes:

[0026] Number both the planar region and each edge of the obstacle surface;

[0027] Obtain the planar region and edges of this obstacle surface in the look-up table, and respectively screen out the planar regions and edges that have a visibility relationship with the planar region and edges in the look-up table;

[0028] And corresponding to the planar region and edges of this obstacle surface respectively, store the numbers of the planar regions and edges that have a corresponding relationship with this planar region and edges in the look-up table corresponding to the planar region or edge.

[0029] In some embodiments of the present invention, the edge region is the space occupied by a cylinder with the edge of the obstacle surface as the height and hemispheres at both ends of the cylinder. The cross-sectional radius of the cylinder is equal to the radius of the hemisphere. The step of, if the ray intersects the obstacle surface in the edge region, determining that diffraction occurs includes:

[0030] Calculate the point on the current propagation direction of the ray that has the shortest distance to the corresponding side of the edge area;

[0031] Calculate the total propagation distance of the ray from the signal emission point to the point with the shortest distance to the corresponding side of the edge area;

[0032] Based on the total propagation distance of the ray from the signal emission point to the point with the shortest distance to the corresponding side of the edge area, calculate the radius of the cylinder. Compare the radius of the cylinder with the shortest distance between the ray and the corresponding side of the edge area in the current propagation direction to determine whether diffraction occurs.

[0033] In some embodiments of the present invention, each time the ray intersects an obstacle surface, it rises one order. Then, the step of obtaining the propagation path of the ray from the signal emission point to the signal reception point for all incoming signal reception points further includes:

[0034] Receive an order threshold, and screen the propagation path from the signal emission point to the signal reception point according to the order of the ray to obtain an effective propagation route.

[0035] In some embodiments of the present invention, after each time the ray is emitted from the emission position, the step of determining whether it enters the signal reception point includes:

[0036] Calculate the point on the current propagation direction of the ray that has the shortest distance to the signal reception point;

[0037] Calculate the total propagation distance of the ray from the signal emission point to the point with the shortest distance to the signal reception point;

[0038] Based on the total propagation distance of the ray from the signal emission point to the point with the shortest distance to the signal reception point, calculate the radius of the signal reception area. Compare the radius of the signal reception area with the shortest distance between the ray and the signal reception point in the current propagation direction to determine whether it enters the signal reception point.

[0039] The present invention also provides a fast ray tracing device applicable to urban scene channel modeling. The device includes a computer device, the computer device includes a processor and a memory, the memory stores computer instructions, and the processor is used to execute the computer instructions stored in the memory. When the computer instructions are executed by the processor, the device implements the steps implemented by the method described above.

[0040] The present invention also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, it implements the steps implemented by the foregoing method.

[0041] Additional advantages, objects, and features of the present invention will be partly set forth in the description which follows, and will partly become apparent to those having ordinary skill in the art upon examination of the following, or may be learned from practice of the present invention. The objects and other advantages of the present invention may be realized and attained by the means particularly pointed out in the specification and drawings.

[0042] Those skilled in the art will understand that the objects and advantages that can be achieved with the present invention are not limited to those specifically described above, and the above and other objects that the present invention can achieve will be more clearly understood from the following detailed description. Brief Description of the Drawings

[0043] The drawings described herein are for further understanding of the present invention, form a part of this application, and do not limit the present invention.

[0044] Figure 1 It is a schematic diagram of an embodiment of a fast ray tracing method applicable to urban scenario channel modeling of the present invention;

[0045] Figure 2 It is a schematic diagram of another embodiment of a fast ray tracing method applicable to urban scenario channel modeling of the present invention;

[0046] Figure 3 It is a top view schematic diagram of a three-dimensional city model of the present invention;

[0047] Figure 4 It is a schematic diagram of the experimental results of the present invention;

[0048] Figure 5 It is a schematic diagram of the signal emission point of the present invention. Detailed Embodiments

[0049] To make the objects, technical solutions, and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with the embodiments and the drawings. Here, the illustrative embodiments and descriptions of the present invention are used to explain the present invention, but do not limit the present invention.

[0050] Here, it should also be noted that in order to avoid obscuring the present invention due to unnecessary details, only the structures and / or processing steps closely related to the solution of the present invention are shown in the drawings, and other details less related to the present invention are omitted.

[0051] It should be emphasized that the term "comprising / including" when used herein refers to the presence of features, elements, steps, or components, but does not exclude the presence or addition of one or more other features, elements, steps, or components.

[0052] Here, it should also be noted that, unless otherwise specified, the term "connection" in this text can not only refer to direct connection, but also represent indirect connection with intermediaries.

[0053] In the following, embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, the same reference numerals represent the same or similar components, or the same or similar steps.

[0054] To solve the above problems, as Figure 1 、 2 shown, the present invention proposes a fast ray tracing method applicable to urban scene channel modeling; the steps of the method include:

[0055] Step S100, receiving a pre-constructed three-dimensional urban model, setting a signal emission point and a signal reception point in the three-dimensional urban model, where the three-dimensional urban model includes a plurality of obstacle models, and each obstacle model includes a plurality of obstacle surfaces;

[0056] In some embodiments of the present invention, the obstacle model in the three-dimensional urban model can be a cuboid model, and both the signal emission point and the signal reception point can be constructed as spheres. If the obstacle model is a cuboid model, then the obstacle surface is the surface of the cuboid.

[0057] Step S200, dividing regions on the top view plane of the three-dimensional urban model, marking the regions where each obstacle model is located, and marking the regions where each obstacle surface is located;

[0058] In some embodiments of the present invention, in the step of dividing regions on the top view plane of the three-dimensional urban model, the top view plane of the three-dimensional urban model is divided into a plurality of regions according to equal area.

[0059] Step S300, after each ray is emitted from the emission position, based on the emission position and emission direction of the ray and performing the step of determining whether it enters the signal reception point, the ray is used to simulate the signal, and the emission position is an obstacle surface or a signal emission point;

[0060] As Figure 5 shown, in some embodiments of the present invention, this solution uses multiple rays uniformly emitted on the sphere to simulate the signal transmission; each intersection point in the figure is the emission point of the ray.

[0061] Step S410, if the ray does not enter the signal reception point, based on the emission position and emission direction of the ray, determine whether the ray intersects with the obstacle model in the region where the emission position is located after being emitted from the emission position;

[0062] In some embodiments of the present invention, the transmission of a signal is simulated as a ray emitted from a signal emission point in all directions. The initial emission position of the ray is the signal emission point. If the ray intersects an obstacle surface during emission, the emission position is the intersecting obstacle surface. The ways of interacting with the obstacle surface include reflection and diffraction.

[0063] Step S411, if there is an intersection, obtain the obstacle surface where the ray intersects the obstacle model, re-determine the emission position and emission direction of the ray, and execute the step of determining whether it enters the signal receiving point;

[0064] In some embodiments of the present invention, if the ray intersects the obstacle model in the area where the emission position is located, continue to calculate the obstacle model in this area, and first determine whether there is an intersection again in this area;

[0065] During the experiment, it is found that in a complex three-dimensional city model, the probability that the ray intersects the obstacle model in the area where the emission position is located after being emitted from the emission position is relatively high. Therefore, the intersection situation with the obstacle model in the area where the emission position is located is calculated preferentially here to improve the calculation efficiency.

[0066] Step S412, if there is no intersection, based on the emission position and emission direction of the ray, determine whether the ray intersects the obstacle surface of the obstacle model after leaving the area where the emission position is located; if so, re-determine the emission position and emission direction of the ray, and execute the step of determining whether it enters the signal receiving point; if not, determine that the ray exits the three-dimensional city model;

[0067] In some embodiments of the present invention, if the ray does not intersect the obstacle model in the area where the emission position is located, based on the relative positions of each area, determine the area into which the ray enters, and then based on the direction of the ray entering the entered area, calculate in the entered area of the ray to determine the intersection situation between the ray and the obstacle model in the entered area; if the ray does not intersect the obstacle model in the area where it first enters, re-determine the area where the ray enters next time until the ray exits the three-dimensional city model or intersects the obstacle model.

[0068] In some embodiments of the present invention, if the ray does not intersect the obstacle model in the area where the emission position is located, in the step of determining the area into which the ray enters based on the relative positions of each area, obtain the adjacent areas of the area where the emission position is located, and calculate the area into which the ray enters according to the emission position and emission direction of the ray among the multiple adjacent areas.

[0069] Step S420, if the ray enters the signal receiving point, obtain the propagation path from the signal emission point to the signal receiving point of all the rays entering the signal receiving point.

[0070] With the above solution, if the ray does not intersect the obstacle model in the area where the emission position is located, the solution of the present application first calculates the area into which the ray enters from the adjacent areas of the area where the emission position is located, and then calculates the intersection situation in the entered area. Each calculation of this solution only needs to be carried out in a small range. For example, in the adjacent areas, calculate the area into which the ray enters, and then calculate in one of the entered areas, which improves the calculation efficiency.

[0071] In some embodiments of the present invention, the three-dimensional city model is established in a three-dimensional coordinate system, and the three-dimensional city model has lengths set on the x, y, and z axes of the three-dimensional coordinate system. If one end of the ray extends beyond the length range of the x, y, or z axis, it is determined that the ray exits the three-dimensional city model.

[0072] With the above solution, first, the three-dimensional city model is divided into multiple areas in the top view plane. In each calculation of the propagation route, it can be calculated starting from the area where the emission position is located. If the ray does not intersect the obstacle model in the area where the emission position is located, the entered area is further determined, and the calculation is carried out in the entered area. Each time, only one area needs to be calculated, and it is not necessary to calculate the entire scene, which optimizes the calculation efficiency.

[0073] In some embodiments of the present invention, the step of receiving the pre-constructed three-dimensional city model further includes marking the area where the obstacle surface is located, and based on the visibility relationship between the obstacle surfaces, obtaining all the obstacle surfaces that have a visibility relationship with each obstacle surface.

[0074] In some embodiments of the present invention, the visibility relationship is that if there is any ray that can directly propagate from one obstacle surface to another between two obstacle surfaces, and there is no interaction with other obstacle surfaces during the propagation from one obstacle surface to the other, it is determined that there is a visibility relationship between the two obstacle surfaces.

[0075] In the specific implementation process, the way that the ray directly irradiates from one obstacle surface to another can be reflection or diffraction.

[0076] With the above solution, the visibility relationship between the obstacle surfaces is determined in advance. Then, when the ray exits from one obstacle surface, it only interacts with the obstacle surfaces that may have a visibility relationship with this obstacle surface. It only needs to judge the interaction with the obstacle surfaces that have a visibility relationship with this obstacle surface. This solution further does not need to calculate all the obstacle surfaces in an area, reduces the calculation amount, and improves the calculation efficiency.

[0077] In some embodiments of the present invention, in the step of determining whether a ray intersects an obstacle model in the area where the ray is emitted based on the emission position and emission direction of the ray, if the emission position is an obstacle surface, it is determined whether the ray intersects an obstacle surface that has a visibility relationship with the obstacle surface at the emission position within the area of the obstacle surface at the emission position;

[0078] In the step of determining whether the ray intersects an obstacle surface of the obstacle model after the ray exits the area where the emission position is located, if the emission position is an obstacle surface, it is determined whether the ray intersects an obstacle surface that has a visibility relationship with the obstacle surface at the emission position in other areas except the emission area.

[0079] In some embodiments of the present invention, in the step of determining whether the ray intersects an obstacle surface that has a visibility relationship with the obstacle surface at the emission position in other areas except the emission area, based on the relative positions of each area and the emission position and emission direction of the ray, the area into which the ray enters is determined, and then based on the direction of the ray entering the entered area, calculations are performed in the entered area of the ray to determine the intersection situation between the ray and the obstacle surface of the entered area; if the ray does not intersect the obstacle surface in the area where it first enters, the area where the ray enters next is determined again until the ray exits the three-dimensional city model or intersects the obstacle surface;

[0080] Based on the relative positions of each area, the areas adjacent to the area where the emission position is located are determined, and the area into which the ray enters is determined among the multiple adjacent areas;

[0081] By adopting the above solution, the present application pre-obtains the visibility relationship between obstacle surfaces, and in the calculation of each area, only the visible surfaces of the obstacle surfaces to be emitted need to be calculated, further improving the calculation efficiency.

[0082] In some embodiments of the present invention, in the step of determining whether a ray intersects an obstacle model in the area where the ray is emitted based on the emission position and emission direction of the ray, if the emission position is a signal emission point, then interactive calculations are performed on all obstacle surfaces in the area where the signal emission point is located according to the emission position and emission direction of the ray to determine whether the ray interacts with an obstacle surface in the area where the signal emission point is located, and if an interaction occurs, the obstacle surface of the interaction is obtained.

[0083] In some embodiments of the present invention, the steps of obtaining all obstacle surfaces that have a visibility relationship with each obstacle surface based on the visibility relationship between obstacle surfaces include:

[0084] Number the obstacle surfaces;

[0085] Based on the visibility relationship of each obstacle surface, a comparison table is established, and the labels of all obstacle surfaces that have a visibility relationship with this obstacle surface are stored in the comparison table.

[0086] In some embodiments of the present invention, in the step of determining the area where the ray intersects based on the emission position and emission direction of the ray if there is no intersection, if the ray does not intersect the obstacle model in the area where the emission position is located, then determine the first incident area according to the emission direction of the ray, and then perform calculations among the obstacle surfaces that are in the incident area and have a visibility relationship with the obstacle surface where the emission position is located based on the obstacle surface where the emission position is located, to obtain the obstacle surface where the ray intersects; if the ray does not intersect the obstacle surface in the first incident area, then determine the next incident area according to the emission direction, and determine again whether there is an intersection until the ray intersects the obstacle surface or exits the ranges of the x, y, and z axes of the three-dimensional city model.

[0087] In some embodiments of the present invention, in the look-up table, the numbers of the obstacle surfaces that have a visibility relationship with each obstacle surface are stored correspondingly for each obstacle surface.

[0088] In some embodiments of the present invention, the obstacle surface includes a planar area and an edge area corresponding to each edge of the obstacle surface. The step of, if there is an intersection, obtaining the obstacle surface where the ray intersects the obstacle model, determining again the emission position and emission direction of the ray, and performing the step of determining whether it enters the signal receiving point includes:

[0089] If the ray intersects the obstacle surface in the planar area, it is determined that reflection occurs, and the emission angle is determined based on the incident angle incident on the planar area to obtain the emission direction;

[0090] If the ray intersects the obstacle surface in the edge area, it is determined that diffraction occurs, and the emission direction is obtained based on the uniform geometrical diffraction theory.

[0091] In some embodiments of the present invention, if the ray intersects the obstacle surface in the planar area, refraction also occurs while reflection occurs, and the refracted ray enters the interior of the obstacle model.

[0092] In some embodiments of the present invention, the step of establishing a look-up table based on each obstacle surface and storing all the obstacle surfaces that have a visibility relationship with the obstacle surface in the look-up table includes:

[0093] Number both the planar area and the edges of each obstacle surface;

[0094] Obtain the planar area and edges of this obstacle surface in the look-up table, and respectively screen out the planar areas and edges that have a visibility relationship with the planar area and edges in the look-up table;

[0095] And corresponding to the planar area and edges of this obstacle surface respectively, store the numbers of the planar areas and edges that have a corresponding relationship with the planar area and edges in the look-up table corresponding to the planar area or edge respectively in the look-up table.

[0096] In some embodiments of the present invention, in the comparison table, there is also correspondingly stored a plane area, an edge area having a visibility relationship with each plane area, and a plane area and an edge area having a visibility relationship with each edge area.

[0097] With the above solution, when a ray is emitted from a plane area or an edge area, if the ray is emitted from a plane area, it is not necessary to perform interactive verification on all obstacle surfaces having a visibility relationship with the obstacle surface where the plane area is located. Only the plane areas and edges having a visibility relationship with the plane area need to be interactively verified. The interactive verification is to determine whether an intersection occurs. This solution can further reduce operations and improve operation efficiency.

[0098] In some embodiments of the present invention, the edge area is the space occupied by a cylinder with the edge of the obstacle surface as the height and hemispheres at both ends of the cylinder. The cross-sectional radius of the cylinder is equal to the radius of the hemisphere. The step of determining diffraction when the ray intersects the obstacle surface in the edge area includes:

[0099] Calculate the point on the ray that is the shortest distance from the corresponding edge of the edge area in the current propagation direction of the ray;

[0100] Calculate the total propagation distance of the ray from the signal emission point to the point that is the shortest distance from the corresponding edge of the edge area;

[0101] Based on the total propagation distance of the ray from the signal emission point to the point that is the shortest distance from the corresponding edge of the edge area, calculate the radius of the cylinder. Compare the radius of the cylinder with the shortest distance between the ray and the corresponding edge of the edge area in the current propagation direction to determine whether diffraction occurs.

[0102] In some embodiments of the present invention, in the step of calculating the point on the ray that is the shortest distance from the corresponding edge of the edge area in the current propagation direction of the ray, the ray is equivalent to a continuous point. Calculate the point among multiple points that is the shortest distance from the corresponding edge of the edge area, and calculate the distance between the two, which is the shortest distance between the ray and the corresponding edge of the edge area in the current propagation direction.

[0103] In some embodiments of the present invention, if the radius of the cylinder is greater than the shortest distance between the ray and the corresponding edge of the edge area in the current propagation direction, it is determined that diffraction occurs.

[0104] Adopting the above solution, in this solution, the transmission of multiple ray analog signals emitted by the signal emission point is simulated. The angle between two adjacent rays is α. As the lengths of the two rays extend, the α angle between the two rays remains unchanged, but the distance at the extended ends of the two rays gradually increases. In this solution, based on the shortest distance between the obstacle surface and the signal emission point, the length extended inward from the edge of the obstacle surface in the edge area is calculated. The longer the shortest distance, the greater the error. Therefore, in this solution, the length extended inward from the edge of the obstacle surface in the edge area is set to be proportional to the shortest distance to make up for the diffraction loss in the simulation process.

[0105] In some embodiments of the present invention, in the step of calculating the radius of the cylinder based on the total propagation distance of the ray from the signal emission point to the point with the shortest distance to the corresponding side of the edge area, the radius of the cylinder is calculated according to the following formula:

[0106] α is the angular interval between adjacent rays, d represents the total propagation distance of the ray from the signal emission point to the point with the shortest distance to the corresponding side of the edge area, and R represents the radius of the cylinder.

[0107] In some embodiments of the present invention, after each time the ray is emitted from the emission position, the step of determining whether it enters the signal reception point includes:

[0108] Calculate the point on the current propagation direction of the ray that is closest to the signal reception point;

[0109] Calculate the total propagation distance of the ray from the signal emission point to the point with the shortest distance to the signal reception point;

[0110] Based on the total propagation distance of the ray from the signal emission point to the point with the shortest distance to the signal reception point, calculate the radius of the signal reception area, and compare the radius of the signal reception area with the calculated shortest distance of the ray on the current propagation direction to the signal reception point to determine whether it enters the signal reception point.

[0111] In some embodiments of the present invention, in the step of calculating the point on the current propagation direction of the ray that is closest to the signal reception point, the ray is equivalent to a continuous series of points, and the point among the multiple points that is closest to the signal reception point is calculated, and the distance between the two is calculated, which is the shortest distance of the ray on the current propagation direction to the signal reception point.

[0112] In some embodiments of the present invention, in the step of calculating the point on the current propagation direction of the ray that is closest to the signal reception point, the signal reception point is the center position of the sphere of the newly received signal.

[0113] In some embodiments of the present invention, if the radius of the signal receiving area is greater than the shortest distance between the ray and the signal receiving point in the current propagation direction, it is determined that the ray can enter the signal receiving point. After determining that the ray can enter the signal receiving point, it is further determined whether the ray intersects with the obstacle surface during the process of propagating from the position where it last intersects with the obstacle surface to the point with the shortest distance to the signal receiving point. If there is an intersection, it is determined that the ray does not enter the signal receiving point, and the emission position and emission angle are re-determined; if there is no intersection, it is determined that the ray enters the signal receiving point.

[0114] In some embodiments of the present invention, before the step of determining that the ray enters the signal receiving point, it also includes determining whether the ray interacts with other obstacle surfaces during the process of propagating from the emission position to the point with the shortest distance to the signal receiving point. If there is no interaction, it is determined that the ray enters the signal receiving point; if there is an interaction, it is determined that the ray does not enter the signal receiving point.

[0115] In some embodiments of the present invention, in the step of calculating the radius of the signal receiving area based on the total propagation distance of the ray from the signal emission point to the point with the shortest distance to the signal receiving point, the radius of the signal receiving area is calculated based on the following formula:

[0116] α is the angular interval between adjacent rays, d1 represents the total propagation distance of the ray from the signal emission point to the point with the shortest distance to the signal receiving point, and R1 represents the radius of the cylinder.

[0117] With the above solution, since the present application uses multiple rays to simulate the propagation of signals, the fork between the ray and the adjacent ray gradually expands during the propagation process, and the influence of the gradually expanding fork on the simulation is not reduced. The above method is used to determine whether the ray enters the signal receiving point.

[0118] In some embodiments of the present invention, each time the ray intersects with the obstacle surface, it rises one order. Then, the step of obtaining the propagation path of the ray from the signal emission point to the signal receiving point for all the rays entering the signal receiving point further includes:

[0119] Receiving the order threshold, and screening the propagation path from the signal emission point to the signal receiving point according to the order of the ray to obtain an effective propagation route.

[0120] The prior art uses methods such as spatial partitioning or dimensionality reduction to accelerate the ray tracing algorithm, or speeds up the calculation on the hardware side by stacking a large number of hardware resources such as GPUs.

[0121] For the spatial partitioning technology, its model will generate redundancy in the part where the ray interacts with the obstacle during multiple operations in the same scene, and the dimensionality reduction method will lose a certain model accuracy, while the hardware acceleration method requires high costs.

[0122] This application provides a fast ray tracing algorithm applicable to urban scenarios. The present invention solves the problem of limited computational efficiency of the current ray tracing-based channel model in complex scenarios. It performs algorithm preprocessing based on the visible relationship of obstacles in the scenario and combines multi-dimensional space partitioning technology to optimize the efficiency of the channel model.

[0123] Experimental example:

[0124] The pre-constructed three-dimensional urban model is as Figure 3 shown. There are 32 buildings in this three-dimensional urban model, and the building height is uniformly 20m. The position of the signal emission point is as Figure 3 shown by TX in Figure 3 and the position of the signal reception point is as

[0125] shown by RX in Figure 4 .

[0126] For the 0th-order ray, it only needs to judge whether the emitted ray can reach the reception point. Since the ray does not interact with the scenario, the running time of the algorithm is the same. In the calculation of the 1st-order ray, the running time of the present invention and the space partitioning algorithm is similar; while the calculation results of higher-order rays show that the algorithm of the present solution is significantly better than the existing space partitioning algorithm and visibility algorithm. According to Figure 4 the data in

[0127] For the calculation of higher-order rays, the algorithm proposed in the present solution has a running time about 50% lower than that of the space partitioning algorithm and is reduced by nearly 70% compared with the traditional visibility algorithm.

[0128] An embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps implemented by the foregoing fast ray tracing method applicable to urban scene channel modeling are realized. The computer-readable storage medium may be a tangible storage medium, such as a random access memory (RAM), memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, register, floppy disk, hard disk, removable storage disk, CD-ROM, or any other form of storage medium known in the art.

[0129] Those of ordinary skill in the art should understand that the various exemplary components, systems, and methods described in conjunction with the embodiments disclosed herein can be implemented in hardware, software, or a combination of both. Specifically, whether to implement in hardware or software depends on the specific application and design constraints of the technical solution. A professional technician can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present invention. When implemented in hardware, it can be, for example, an electronic circuit, an application-specific integrated circuit (ASIC), appropriate firmware, a plug-in, a functional card, etc. When implemented in software, the elements of the present invention are programs or code segments used to perform the required tasks. The program or code segment can be stored in a machine-readable medium or transmitted through a data signal carried in a carrier wave on a transmission medium or a communication link.

[0130] It should be clear that the present invention is not limited to the specific configurations and processes described above and shown in the figures. For the sake of brevity, detailed descriptions of known methods are omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of the present invention is not limited to the specific steps described and shown. Those skilled in the art can make various changes, modifications, and additions, or change the order between steps after understanding the spirit of the present invention.

[0131] In the present invention, the features described and / or illustrated for one embodiment can be used in the same way or in a similar way in one or more other embodiments, and / or combined with the features of other embodiments or replace the features of other embodiments.

[0132] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, various changes and modifications can be made to the embodiments of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A fast ray tracing method applicable to urban scene channel modeling, characterized in that, The steps of the method include: Receiving a pre-constructed three-dimensional city model, setting signal emission points and signal reception points in the three-dimensional city model, where the three-dimensional city model includes multiple obstacle models, and each obstacle model includes multiple obstacle surfaces; Dividing regions on the top view plane of the three-dimensional city model, marking the regions where each obstacle model is located, and marking the regions where each obstacle surface is located; After each ray is emitted from the emission position, it is determined whether the ray enters the signal reception point based on the emission position and emission direction of the ray. The ray is used to simulate the signal, and the emission position is an obstacle surface or a signal emission point; If the ray does not enter the signal reception point, it is determined whether the ray intersects with the obstacle model in the region where the ray is emitted based on the emission position and emission direction of the ray; If there is an intersection, obtain the obstacle surface where the ray intersects with the obstacle model, determine the emission position and emission direction of the ray again, and execute the step of determining whether the ray enters the signal reception point; If there is no intersection, based on the emission position and emission direction of the ray, determine whether the ray intersects with the obstacle surface of the obstacle model after leaving the region where the ray is emitted; if so, determine the emission position and emission direction of the ray again, and execute the step of determining whether the ray enters the signal reception point; if not, it is determined that the ray exits the three-dimensional city model; If the ray enters the signal reception point, obtain the propagation path of all the rays entering the signal reception point from the signal emission point to the signal reception point.

2. The fast ray tracing method applicable to urban scene channel modeling according to claim 1, characterized in that, The step of receiving the pre-constructed three-dimensional city model further includes marking the regions where the obstacle surfaces are located, and based on the visibility relationship between the obstacle surfaces, obtaining all the obstacle surfaces that have a visibility relationship with each obstacle surface.

3. The fast ray tracing method applicable to urban scene channel modeling according to claim 2, characterized in that In the step of determining whether the ray intersects with the obstacle model in the region where the ray is emitted based on the emission position and emission direction of the ray, if the emission position is an obstacle surface, determine whether the ray intersects with the obstacle surfaces that have a visibility relationship with the obstacle surface at the emission position within the region of the obstacle surface at the emission position; In the step of determining whether the ray intersects with the obstacle surface of the obstacle model after leaving the region where the ray is emitted, if the emission position is an obstacle surface, determine whether the ray intersects with the obstacle surfaces that have a visibility relationship with the obstacle surface at the emission position in other regions except the emission region.

4. The fast ray tracing method applicable to urban scene channel modeling according to claim 2, characterized in that, The step of obtaining all the obstacle surfaces that have a visibility relationship with each obstacle surface based on the visibility relationship between the obstacle surfaces includes: Numbering the obstacle surfaces; Establishing a look-up table based on the visibility relationship of each obstacle surface, and storing the labels of all the obstacle surfaces that have a visibility relationship with this obstacle surface in the look-up table.

5. The fast ray tracing method applicable to urban scene channel modeling according to claim 2, characterized in that, The obstacle surface includes a planar region and an edge region corresponding to each edge of the corresponding obstacle surface. The step of if there is an intersection, obtain the obstacle surface where the ray intersects with the obstacle model, determine the emission position and emission direction of the ray again, and execute the step of determining whether the ray enters the signal reception point includes: If the ray intersects with the obstacle surface in the planar region, it is determined that reflection occurs, and the exit angle is determined based on the incident angle incident on the planar region to obtain the emission direction; If the ray intersects the obstacle surface in the edge area, diffraction is determined to occur, and the outgoing direction is obtained based on the uniform geometrical theory of diffraction.

6. The fast ray tracing method applicable to urban scene channel modeling according to claim 5, characterized in that, The step of establishing a look-up table based on each obstacle surface and storing all obstacle surfaces having a visibility relationship with the obstacle surface in the look-up table includes: Numbering the plane area and the edges of each obstacle surface; Obtaining the plane area and the edges of the obstacle surface in the look-up table, and respectively screening out the plane areas and the edges having a visibility relationship with the plane area and the edges in the look-up table; And corresponding to the plane area and the edges of the obstacle surface respectively, storing the numbers of the plane areas and the edges having a corresponding relationship with the plane area and the edges in the look-up table corresponding to the plane area or the edges.

7. The fast ray tracing method applicable to urban scene channel modeling according to claim 5, characterized in that The edge area is the space occupied by a cylinder with the edge of the obstacle surface as the height and hemispheres at both ends of the cylinder. The radius of the cross-section of the cylinder is equal to the radius of the hemispheres. The step of determining that diffraction occurs if the ray intersects the obstacle surface in the edge area includes: Calculating the point on the ray that is the shortest distance from the corresponding edge of the edge area in the current propagation direction; Calculating the total propagation distance of the ray from the signal emission point to the point that is the shortest distance from the corresponding edge of the edge area; Calculating the radius of the cylinder based on the total propagation distance of the ray from the signal emission point to the point that is the shortest distance from the corresponding edge of the edge area, comparing the radius of the cylinder with the shortest distance calculated for the ray from the corresponding edge of the edge area in the current propagation direction, and determining whether diffraction occurs.

8. The fast ray tracing method applicable to urban scene channel modeling according to any one of claims 1-7, characterized in that Each time the ray intersects an obstacle surface, it ascends one order. The step of obtaining the propagation path of the ray from the signal emission point to the signal reception point for all incoming signal reception points further includes: Receiving an order threshold value, screening the propagation path from the signal emission point to the signal reception point according to the order of the ray, and obtaining an effective propagation route.

9. The fast ray tracing method applicable to urban scenario channel modeling according to claim 1, wherein After the ray is emitted from the emission position each time, the step of determining whether it enters the signal reception point includes: Calculating the point on the ray that is the shortest distance from the signal reception point in the current propagation direction; Calculating the total propagation distance of the ray from the signal emission point to the point that is the shortest distance from the signal reception point; Calculating the radius of the signal reception area based on the total propagation distance of the ray from the signal emission point to the point that is the shortest distance from the signal reception point, comparing the radius of the signal reception area with the shortest distance calculated for the ray from the signal reception point in the current propagation direction, and determining whether it enters the signal reception point.

10. A fast ray tracing device applicable to urban scene channel modeling, characterized in that, The device includes a computer device, the computer device includes a processor and a memory, the memory stores computer instructions, and the processor is used to execute the computer instructions stored in the memory. When the computer instructions are executed by the processor, the device implements the steps implemented by the method according to any one of claims 1-9.

Images