KR19980052396A - Propagation Path Tracking Method Using Electrical Image Tree - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a propagation path tracking method in a propagation path tracking system.

2. The technical problem to be solved by the invention

The present invention is to provide a propagation path tracking method for predicting propagation path loss by describing the propagation environment of the micro cell and pico cell of the mobile communication system in the propagation path tracking system.

3. Summary of Solution to Invention

The present invention repeatedly generates an electrical image generated by each building surface within a region to be analyzed for a given transmitter by a specified number of reflections and diffractions, and stores the data as a tree structure. By searching these trees based on the position of, we trace the propagation path from the transmitter back to the receiver and find it backwards, so we only search for the propagation path that actually reaches the receiver and not the other propagation paths. The execution time can be significantly reduced.

4. Important uses of the invention

Used to predict the propagation environment of micro cells and pico cells.

Description

Propagation Path Tracking Method Using Electrical Image Tree

The present invention relates to a propagation path tracking method for predicting propagation path loss by describing the propagation environment of a micro cell and a pico cell of a mobile communication system in a propagation path tracking system. The present invention relates to a propagation path tracking method that searches only a propagation path that actually reaches a receiver and does not search other propagation paths.

Recently, due to the surge in demand for mobile communication, researches on microcells and picocells to accommodate more subscribers with limited frequency resources have been actively conducted.

This shows that as the demand for wireless communication increases, cell technology is gradually reduced in terms of capacity growth and call quality.

Here, the micro cell is a cell within a radius of 1km, and there are many different points from the existing macro cell, and in particular, there is a marked difference in the radio wave propagation environment.

In the macro cell, the propagation environment is characterized by the distribution of the terrain and the building, whereas in the micro cell, the propagation environment is characterized by the shape and layout of each building in addition to the terrain and the distribution of the building. This is because micro cell technology is mostly applied to systems for low-speed pedestrians, because micro cells require less transmit power (typically less than 100 m watts) depending on the cell size within less than 1 km and the antenna height is low.

Therefore, an experimental propagation model for describing a radio wave propagation environment of a macro cell is not suitable to be applied to a micro cell as it is, and a new propagation model for describing the radio wave propagation environment of a micro cell is required.

Currently, the ray tracing model based on the Uniform Geometrical Theory of Diffraction (UTD) is recognized as the best model for describing the propagation environment of the micro cell. Here, the electromagnetic wave beam approximation (UTD) can be used for the propagation path prediction of the electromagnetic signal of the quasi microwave band or more, and is calculated using reflection or diffraction characteristics. However, such a conventional ray tracing method has a problem that the simulation execution time takes a very long time.

Therefore, many people have studied the radio wave environment prediction technique with flexible and efficient calculation process in order to apply to problems such as base station station in consideration of terrain data and radio wave loss in micro cell environment.

Simulation execution time by a conventional ray tracing method is determined by a method of finding a propagation path through which electromagnetic waves radiated from a transmitter reach a receiver. Conventional ray tracing methods can be classified into two types, a ray shooting method and a ray tube method.

Here, a ray shooting method is a method of finding a ray that reaches a reception point by tracking each ray after firing a plurality of rays at equal intervals from a transmission point.

On the other hand, in the Ray Tube method, as shown in FIG. 1, after firing a plurality of Ray Tubes at equal intervals from the transmission point, each Ray Tube is traced to reach the receiving point. How to find (Ray Tube). 1 is an exemplary view of finding a propagation path using a conventional Ray Tube method. Here, a ray tube is a bundle of a plurality of rays, and it is assumed that all rays in the same ray tube have the same value.

When using the conventional Ray shooting method and the Ray Tube method, it takes a lot of simulation execution time by searching not only the propagation path that actually reaches the receiver but also the propagation path that does not reach the receiver. there was.

In order to solve the above problems, the present invention repeatedly generates an electric image generated by each building surface in a region to be analyzed for a given transmitter by a specified number of reflections and diffractions, and a tree structure. After searching the tree based on the position of a given receiver after storing the data as, it traces back the propagation path from the transmitter to the receiver and finds only the propagation path actually reaching the receiver. The purpose of the present invention is to provide a propagation path tracking method that can significantly reduce simulation execution time since the propagation path is not searched.

1 is an exemplary view of finding a propagation path using a conventional Ray tube method;

2 is an exemplary view of finding a propagation path using a propagation path tracking method for calculating a reflection point;

3 is a flowchart of a propagation path tracking method for calculating a reflection point according to the present invention;

4 is an exemplary view of finding a propagation path by using a propagation path tracking method including diffraction gum calculation;

5 is a flowchart of a propagation path tracking method including diffraction inspection according to the present invention;

6 is a schematic diagram of the formation of an electrical imaging tree and a tree traceback process for a transmitter.

One embodiment of the present invention for achieving the above object, in the propagation path tracking method applied in the propagation path tracking system, the ray tube due to the reflection of the radio wave to find the position of the electrical image from the building surface found on the transmitter side ( A first step of generating a Ray Tube and storing the same in an electrical image tree structure; A second step of repeating the process of finding an electrical image from the building surfaces found on the generated ray tube and generating a ray tube and storing the ray tube as an electrical association tree structure up to a predetermined number of reflections; And retrieving a propagation path from the transmitter to the receiver in reverse from the transmitter to the transmitter by retrieving Ray Tube data in an electrical image tree structure based on a given receiver position. .

Meanwhile, according to another embodiment of the present invention, in the propagation path tracking method applied to the propagation path tracking system, a virtual receiver is placed at each corner of a building surface and arrives at the virtual receiver from the transmitter using a reflection point calculation method. A first step of repeating a process of generating an electrical image tree for the virtual transmitter by applying a reflection point calculation method by placing a virtual transmitter at each corner of the building surface after finding a propagation path; A second step of finding a propagation path at the virtual transmitter (diffraction point) to the actual receiver via a direct path or multiple building surface reflections; And a third step of combining a propagation path to the virtual receiver with a propagation path to the actual receiver to find a propagation path composed of a combination of reflections and diffractions and measuring propagation loss at a reception point.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, the terms used in the present footing are defined as follows.

The diffraction refers to the scattering phenomenon formed by the electromagnetic wave incident on the scattering body at the discontinuous point.

Each electrical image of the tree, together with each side it belongs to, forms a kind of Ray Tube.

Ray tube in the present invention is defined as a tube (tube) representing the range that can be reached by the reflected wave by a certain building surface, unlike the definition in the conventional method.

In order to apply the method of the present invention, it is necessary to approximate the terrain and building data according to the following three basic assumptions.

First, we approximate all buildings to polygonal dielectrics of constant height.

Second, the walls of all buildings are approximated with a rectangle that is always perpendicular to the ground.

Third, the ground is flat.

2 is an exemplary view of finding a propagation path using a propagation path tracking method for calculating a reflection point, and FIG. 3 is a flowchart of the propagation path tracking method for calculating a reflection point according to the present invention.

Ray propagation is reflected by diffraction and diffraction by surrounding buildings, and reaches the receiver from the transmitter through the reflection path of the building surface as shown in FIG.

Looking at the specific operation, it determines the location (transmission point) of the transmitter (31) and finds the building surfaces that the transmitter can see for a given building (32). At this time, find part or all of each building surface.

Find the position of the electric image from the building surfaces obtained above (33) and determine three parameters of the position of the electric image, the number of the building surface to which it belongs, and the propagation path range angle (for example, α _{1 in} FIG. ₁ ) by the image. A ray tube due to the reflected radio waves is formed (34). At this time, the ray tube by each electric image is stored in a tree structure having the transmission point as a parent.

The building surface can be viewed by the Ray Tube by each electric image generated above (35) and the position of the electric image is found from the found building surfaces (36). A ray tube is generated by using the location, the number of the building surface to which it belongs, and the propagation path range angle (for example, α ₂ of FIG. 1) based on the image. At this time, the ray tube generated by each of the generated electrical images is stored in a tree structure parenting previous electrical images.

When the electrical image tree is formed by two reflections as described above, the number of reflections is compared with a desired threshold value, and if the number of reflections is still smaller than the threshold value, the second electrical image tree forming process (35 to 37) is repeated, and the number of reflections is repeated. When is the threshold is performed (38), wherein the formed electric image tree has the same structure as the example of FIG.

Then, when the number of reflections reaches a threshold, the building surfaces that can be viewed by the receiver with respect to the given receiver are searched (39). At this time, a part or the whole of each building surface is found. Subsequently, the electronic images belonging to the building surface found on the receiver side are found from the formed electrical image tree (40).

The ray tube including the receiver is found among the ray tubes represented by the electrical images found in the above process (41). The number of Ray Tubes thus found is the total propagation path (42).

The propagation path is then tracked from the receiver to the transmitter using an electrical image tree structure describing the found Ray Tubes (43). In this case, as shown in FIG. 2, the intersection point between the lines connecting the respective electric images and the buildings belonging to each other is a reflection point at the building surface, and the line connecting the transmitter, the receiver and the reflection points is a propagation path.

Thereafter, the number of ray tubes is compared with the number of propagation paths (44), and if the number of ray tubes is still smaller than the number of propagation paths, the process is repeated from step 41 of finding a ray tube including the receiver, and the number of ray tubes is propagated. When the number is reached, the total propagation loss at the receiving point is calculated by adding signals for each propagation path by the number of propagation paths found (45).

4 is an exemplary view of finding a propagation path by using a propagation path tracking method including a diffraction gum calculation, and FIG. 5 is a flowchart of the propagation path tracking method including a diffraction gum estimation according to the present invention.

One of the most important considerations in propagation loss prediction is the diffraction phenomenon. An example for applying the effect of diffraction in addition to reflection on the propagation path is shown in FIG. 4. The electric image 1 represents an electric image by the transmitter Tx, and the electric images a and b represent the electric image by the diffraction points. There are two ray paths from the transmitter to the diffraction point and three ray paths from the diffraction point to the receiver Rx. This results in six (2x3) ray paths from the transmitter to the receiver.

Looking at the specific operation, a virtual receiver is placed at each corner of a given building (51). If it is the first iteration number (52), if it is the first iteration number, the propagation path arriving at each virtual receiver from the actual transmitters through the multiple reflections from the reflection point calculation method of the building surface is found (53), and from the second iteration number From the reflection point estimation method of the building surface, find the propagation path arriving from each virtual transmitter to each virtual receiver through multiple reflections (54).

After finding the propagation path, virtual transmitters are placed at each corner of given buildings, and the reflection point estimation method is applied to form electrical image trees for each virtual transmitter (55).

Thereafter, the number of repetitions is compared with the number of diffractions (56). If the number of repetitions is smaller than the number of diffractions, the process is repeated from the first step (51). Or find the propagation path to the actual receiver through the reflection of the building surface (57).

By combining the propagation path to the virtual receiver and the propagation path to the actual receiver, the propagation path consisting of a combination of reflection and diffraction is found (58). Measure (59).

As described above, when considering the reflection point and the diffraction point caused by the difference between the ground reflection and the height difference between the transmitting and receiving antennas in the propagation path found through the building surface reflection point estimation technique and the building surface diffraction point estimation technique, The two-dimensional approximation characteristic can be applied.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the spirit of the present invention for those skilled in the art to which the present invention pertains, and the above-described embodiments and accompanying It is not limited to the drawing.

As described above, the present invention develops a new reflection point and diffraction point calculation algorithm applied to a ray tube technique for estimating propagation loss, so that a loss effect on reflection and diffraction can be efficiently performed while having a relatively small calculation amount. In consideration of this, it is possible to predict more reliable propagation loss.

Claims (6)

In the propagation path tracking method applied in the propagation path tracking system, A first step of finding a location of the electric image from the building surfaces found by the transmitter and generating a ray tube due to reflected radio waves and storing the ray tube in an electric image tree structure; A second step of repeating the process of finding an electrical image from the building surfaces found on the generated ray tube and generating a ray tube and storing the ray tube as an electrical association tree structure up to a predetermined number of reflections; And And retrieving the propagation path from the transmitter to the receiver back from the transmitter to the transmitter by retrieving Ray Tube data in an electrical image tree structure based on a given receiver position. Propagation Path Tracking Method. The method of claim 1, The first step is, Finding the building faces the transmitter faces to a given building after determining the location (transmission point) of the transmitter; Finding the location of the electrical image from the found building surfaces; And An electrical image tree parented by a transmission point by creating a ray tube due to reflected radio waves using the location of the found electrical image, the number of the building surface to which it belongs, and the propagation path range angle by the found electrical image. A propagation path tracking method comprising the step of storing in a structure. The method of claim 2, The second step, Finding building surfaces viewed by the generated Ray Tube; Locating the electrical images from the buildings found by Leytub; Electricity that creates a ray tube using the location of the electric image by the found building surface, the number of the building surface to which it belongs, and the angle of the propagation path range by the electric image. Storing the image tree structure; And When the number of repetitions is smaller than a predetermined threshold by comparing the number of reflections with a desired threshold, the method is repeated from the step of finding the buildings viewed by the generated Ray Tube, and when the number of repetitions reaches the predetermined threshold, the third step is performed. A propagation path tracking method comprising the step of performing. The method according to any one of claims 1 to 3, The third step, Finding electrical images belonging to the building surface found on the receiver side from the electrical image tree generated after finding the building surfaces viewed by the receiver; Calculating a number of Ray Tubes as a propagation path number by finding a Ray Tube including the receiver among the Ray Tubes represented by the found electrical images; Tracking a propagation path back from the receiver to the transmitter using an electrical image tree structure representing the found Ray Tubes; And When the number of ray tubes is smaller than the number of propagation paths, the number of ray tubes is smaller than the number of propagation paths, and the process is repeated until the ray tube including the receiver is found. Estimating a total propagation loss at the receiving point. In the propagation path tracking method applied to the propagation path tracking system, After finding the propagation path from the transmitter to the virtual receiver by using the reflection point estimation method for each corner of the building surface, the virtual transmitter is placed at each corner of the building surface to apply the reflection point estimation method. A first step of repeatedly generating the electrical image tree for the transmitter of the transmitter up to a predetermined number of diffraction times; A second step of finding a propagation path from the virtual transmitter (diffraction point) to the actual receiver through a direct path or multiple building surface reflections; And A propagation path including a third step of combining a propagation path to the virtual receiver with a propagation path to the actual receiver to find a propagation path composed of a combination of reflections and diffractions and measuring propagation loss at a reception point; Tracking method. The method of claim 5, The first step is, Determining whether it is the first iteration number after setting a virtual receiver at each corner of a given building; As a result of the above determination, if the first repetition number is used, the propagation path reaching the virtual receiver from the actual transmitters is found through multiple reflections using the method of calculating the reflection point of the building surface. Finding a propagation path from the virtual transmitters to each virtual receiver through multiple reflections using the method; After finding the propagation path, setting virtual transmitters at each corner of a given building, and then generating an electrical image tree for each virtual transmitter using a reflection point estimation method; And And repeating the number of repetitions from the number of repetitions when the number of repetitions is smaller than the number of diffractions, and performing the second step when the number of repetitions reaches a desired number of diffraction.