KR100222669B1 - Smoothing method of digital terrain map for microwave propagation analysis - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

Smoothing method of digital terrain model for radio wave analysis.

2. The technical problem to be solved by the invention

The smoothing resolution is used to maintain the curvature where the change of the height value from the previous scale is greater than the smoothing resolution in the digital terrain model grid, and only if it is not, smoothing is performed to ensure the accuracy of the wireless network design.

3. Summary of Solution to Invention

Determines the maximum position of the Fresnel radius by calculating the change in the antenna position, the predicted radius, and the antenna position from the antenna position at equal intervals, calculating the smoothing resolution, and increasing the distance from 0 to the predicted radius by increasing the value. After the amount of change in the altitude value is calculated, when the amount of change in each altitude is greater than the smoothing resolution, the altitude value is kept as it is, and when the amount of change in the altitude value is less than or equal to the smoothing resolution, smoothing is performed.

4. Important uses of the invention

Used in wireless network design system.

Description

Smoothing method of numerical terrain model for radio wave analysis {SMOOTHING METHOD OF DIGITAL TERRAIN MAP FOR MICROWAVE PROPAGATION ANALYSIS}

The present invention provides a smoothing resolution during smoothing of a digital terrain map (DTM) for digitizing profile information of a terrain in a radio wave propagation module of a wireless network design system. The present invention relates to a smoothing method of a digital topographic model for radio wave analysis that enables accurate prediction in designing a wireless network by maintaining the overall topography while maintaining the curvature that may affect the progress of radio waves.

Digital Terrain Model (DTM) is a digitization of the topography of the terrain. The DTM is terrain data that creates grids of appropriate intervals according to the purpose and stores altitude and speed information for each grid scale.

The wireless network design system sets the location of the base station based on the geographic information, and performs the function of estimating the propagation signal strength around the base station when the antenna is installed at the point. At this time, a part of predicting the signal strength in a predetermined area around the base station is a radio wave propagation analysis module.

In this case, since the strength of the received radio wave is greatly influenced by the nearby terrain and various geographical conditions, a numerical topography model is introduced and used in the calculation process. The more accurate the prediction, the more efficient the wireless network can be designed, so DTM is introduced to make accurate prediction. In this process, it is necessary to properly reprocess the digital terrain model in consideration of the accuracy and efficiency of the system.

In other words, the radio wave propagation analysis module of the wireless network design system uses a radio wave analysis DTM that digitizes the topographical information of the terrain in order to make a more accurate prediction. When calculating the signal strength of radio waves, it is required to reprocess the DTM before calculating the signal strength in loading and using terrain information. This is because, if the curvature of the terrain is too dense, it depends on the nature of the system using the DTM, but it can introduce various complexity in calculations, statistics, and analysis.

In general, many applications using a digital terrain model also undergo internal DTM reprocessing. This is because, if the DTM has not been reprocessed, minor terrain curvature may lead to an increase in computation, putting more load on the system than necessary, or the effect of curvature may accumulate and produce undesirable results.

Therefore, a method for maintaining efficiency while maintaining efficiency while smoothing excessive bends according to the general tendency of the region through an appropriate algorithm for the purpose of the system is required.

In the case of a wireless network design system, the smoothing process eliminates the size of the curvature that has little effect on the propagation of the radio waves. In addition, according to the characteristics of the propagation model to be used to prevent serious adverse effects that may occur when not smoothed.

In the case of a propagation model in which the parameter Effective Antenna Height is used, this effective antenna height correlates to the angle that the ground on which the antenna is placed forms the sea level. If the ground near the antenna is steeply steeper than the slope of the terrain, the effective antenna height is very different from the actual one, causing serious errors in the radio wave analysis results.

As a representative example of a smoothing method generally used in the related art, there is a smoothing method using an arithmetic mean. The conventional smoothing method using an arithmetic mean is performed by dividing a target area at appropriate intervals and taking an arithmetic mean of altitude information values falling within the scale.

Referring to FIG. 2, a smoothing method using a conventional arithmetic mean will be described in more detail.

When the value is readjusted by the arithmetic mean, as in the case of the area A and the area B in Fig. 2, the total volume multiplied by the surface area and the altitude does not change in the actual three-dimensional space. Thus, civil engineering or water management systems, which are volume handling systems, may not be affected.

However, in the radio wave analysis module of the wireless network design system, problems may occur when using arithmetic mean. This can prevent the errors as described above as the excessive bend smoothes, but because the arithmetic average method is used, the topographical bend that should actually affect the propagation is buried as shown in FIG. Therefore, when such a situation occurs, there is a problem that a significant difference may occur between the predicted signal strength and the actual signal strength.

In order to solve the problems described above, the present invention, in the radio wave propagation analysis module of the wireless network design system using the smoothing resolution at the time of smoothing the digital terrain model (DTM) grid in the digital terrain model (DTM) grid By maintaining the curvature with a change in the height value of the smoothing resolution or higher, and smoothing only when it is not, the curvature of the size that can affect the propagation of the wave can be maintained while maintaining the overall appearance of the terrain. The purpose of the present invention is to provide a smoothing method of a digital terrain model for radio wave analysis for accurate prediction.

1 is an explanatory diagram showing a smoothing result of a general digital terrain model (DTM),

2 is an explanatory diagram showing a smoothing result using a conventional arithmetic mean,

3 is a flowchart illustrating an embodiment of a smoothing method of a digital terrain model for radio wave analysis according to the present invention;

4 is a detailed flowchart illustrating a smoothing resolution calculation process in the smoothing method of the digital terrain model for radio wave analysis according to the present invention;

5 is an explanatory diagram of a Fresnel region and a Fresnel radius used in the present invention,

6 is an explanatory diagram showing a smoothing result using a smoothing resolution used in the present invention.

According to an aspect of the present invention, there is provided a smoothing method of a digital terrain model for radio wave analysis applied to a radio wave propagation analysis module of a wireless network design system, wherein the antenna position, a predicted radius, and the antenna position to the predicted radius are uniform. Calculating a smoothing resolution by determining a parameter of a change increasing value divided by one interval to obtain a maximum Fresnel radius; The distance from the antenna position to the predicted radius is increased by the change increase value until the distance from the antenna position to the predicted radius is equal to the predicted radius. Calculating a change in height value from a previous scale); And a third step of maintaining the curvature in which the height value change with the previous scale in the digital terrain model grid is equal to or greater than the calculated smoothing resolution, and otherwise performing smoothing.

The present invention is a methodology of how to peacefulize the electronically mapped hills, which is a process to be performed before calculating the path loss, which corresponds to the preprocessing of the terrain data in the wireless network design system.

The smoothing method already knows how the path loss is calculated when there is an obstacle, so the terrain data is properly processed according to the method. However, since the topographical data is grid-like digital data, the value between two adjacent pixels in the grid data is discontinuously changed. To compensate for this discontinuous change, GIS application uses a lot of smoothing techniques, and the general formula is used a lot. However, since the present invention is made in a wireless network design system, and has a special purpose that the terrain data being handled is used to calculate the path loss of the radio wave, the present invention intends to perform leveling under conditions suitable for this purpose.

Therefore, the present invention uses the smoothing resolution when the digital terrain model (DTM) is smoothed in the radio wave propagation module of the wireless network design system, and the change of the height value from the previous grid in the digital terrain model (DTM) grid is equal to or greater than the smoothing resolution. By keeping it as is, and performing smoothing only when it is not, it is possible to maintain the overall appearance of the terrain while maintaining the curvature of the size that may affect the propagation of the radio wave, thereby making accurate predictions in the design of the wireless network.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Hereinafter, an embodiment of the present invention will be described in detail with reference to FIGS. 3 to 6.

3 is a flowchart illustrating a smoothing process of a digital terrain model in a radio wave propagation module according to an embodiment of the present invention.

As shown in FIG. 3, in the radio wave propagation module according to the present invention, the smoothing method of the digital terrain model for radio wave analysis first receives a variable value necessary for the smoothing process for reprocessing the digital terrain model from the radio wave propagation module ( 101). That is, an arbitrary change increase value del_r, which is a size of a storage bin that divides the antenna position, the predicted radius R determined from the radio wave propagation model and the predicted radius R from the antenna, is input.

Then, the smoothing resolution ?? h is determined using the input values (102). A process of calculating the smoothing resolution will be described in more detail with reference to FIG. 4.

If the smoothing resolution ?? h is too large, the curvature of the terrain to be considered may be ignored, or if it is too small, the curvature to be ignored may affect the environment of radio wave propagation. Therefore, the relationship between the electromagnetic wave and the obstacle affecting the progress of the electromagnetic wave should be derived by considering physically. Accordingly, in the present invention, the smoothing resolution ?? h is derived by using the Fresnel radius as the initial equation.

The Fresnel radius is defined from the Fresnel zone, which is a spatial region of a continuous ellipsoid whose focal point is a transmit antenna and a receive antenna, respectively, as shown in FIG. The successive ellipsoids differ in the sum of the distances between the two focal points by an integer multiple of half-wavelength. As shown in FIG. 5, the radius of the intersection plane between the Fresnel region and the plane vertically dividing between the transmitting antenna and the receiving antenna is the Fresnel radius.

First, the physical meaning of the Fresnel region is the region that contains most of the energy propagated from the transmitting antenna. In other words, the Fresnel radius can be said to be the range in which the traveling electromagnetic waves actually affect the periphery of the traveling axis. It is intuitively clear that an object of size beyond this range will obstruct the progress of electromagnetic waves.

As shown in Figure 4, the smoothing resolution calculation process of the smoothing method of the digital terrain model for radio wave analysis according to the present invention, first, Fresnel radius which is the minimum size of the object affecting the propagation through (Equation 1) Calculate 201.

Here, f is the use frequency [MHz], d_1 represents the distance [Km] from the transmitting antenna, and d_2 represents the distance [Km] from the receiving antenna.

Then, the maximum Fresnel radius of the thus obtained Fresnel radius is calculated (202). When the distance from the transmitting antenna is equal to the distance from the receiving antenna, that is, when d_1 = d_2 = d / 2 (d = distance between the transmitting and receiving antennas), the Fresnel radius becomes maximum. The result is the same as (Equation 2).

The distance d between the transmitting and receiving antennas is set to a radius R for radio wave analysis from the transmitting antenna of the base station in the wireless network design system. Therefore, instead of d, which is the distance between the transmit and receive antennas of Equation 2, the predicted radius R is substituted (203).

The coefficient " 274 " used in the equation can be changed according to the characteristics of the terrain, and needs to be properly adjusted for more accurate signal strength prediction due to the characteristics of the wireless network design system. Therefore, in this embodiment, the coefficient "274" is made constant and the range of the constant C1 is set from 100 to 400 (204).

The smoothing resolution ?? h used in the present invention is calculated as Equation (3).

(여기서, 100 < C1 < 400)

Where 100 <C1 <400

After calculating the smoothing resolution through the above process (102), while increasing the distance r from the antenna position to the predicted radius R by increasing value del_r (103), the change amount of the altitude value H of the digital terrain model is calculated (104). . If the change amount del_H of the altitude value is greater than the smoothing resolution ?? h (105), the altitude value H remains as it is; otherwise, if the change amount del_H of the altitude value is less than or equal to the smoothing resolution ?? h (105), the altitude value H is Smoothing (106). The amount of conversion of the altitude value H is calculated while increasing r by an increasing value until the distance r from the antenna position to the predicted radius R is equal to the predicted radius R (107) (103, 104).

In the present invention as described above, when the curvature A of which the change in the altitude value is equal to or more than the smoothing resolution value is in the topography, the result of using the arithmetic mean method is buried in the entire topography in FIG. It remains even after execution. Therefore, by using the smoothing resolution in the smoothing process, it is possible to maintain the topography of the terrain while maintaining the appearance of the terrain while maintaining the curvature of the size that may affect the progress of the radio wave can be accurately predicted when designing the wireless network.

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

The present invention as described above, by using the smoothing resolution in the smoothing process, it is possible to maintain the appearance of the terrain while performing the overall smoothing while maintaining the curvature of the size that may affect the progress of the radio wave as it is, accurate prediction when designing the wireless network This has a possible effect.

Claims (6)

(delete) (correction) In the method of smoothing a digital terrain model for radio wave analysis applied to a radio wave analysis module of a wireless network design system, Calculating a smoothing resolution by determining a maximum Fresnel radius by determining a parameter of a change increase value obtained by dividing the antenna position, the predicted radius, and the antenna position from the antenna position to the predicted radius at uniform intervals; The distance from the antenna position to the predicted radius is increased by the change increase value until the distance from the antenna position to the predicted radius is equal to the predicted radius. Calculating a change in height value from a previous scale); And A third step of maintaining the curvature in which the height value change with the previous scale is greater than the calculated smoothing resolution in the digital terrain model grid; otherwise, smoothing is performed. Smoothing method of digital terrain model for radio wave analysis, including. (correction) The method of claim 2, The process of calculating the smoothing resolution of the first step, A fourth step of calculating a Fresnel radius, which is the minimum size of the object affecting propagation propagation; A fifth step of calculating a maximum Fresnel radius among the calculated Fresnel radius; A sixth step of substituting the predicted radius value into the distance value between the transmit and receive antennas used in the calculation of the maximum Fresnel radius of the fifth step; And A seventh step of obtaining smoothing resolution by parameterizing and substituting a coefficient value for more accurate signal strength prediction in terms of system characteristics when calculating the maximum Fresnel radius in the fifth step Smoothing method of digital terrain model for radio wave analysis, including. (correction) The method of claim 3, wherein The process of calculating the Fresnel radius r of the fourth step, A method for smoothing a digital terrain model for radio wave analysis, which is calculated by the following equation using the use frequency f, the distance d_1 from the transmitting antenna, and the distance d_2 from the receiving antenna.

(correction) The method according to any one of claims 2 to 4, The maximum Fresnel radius is, And the distance d_1 from the transmitting antenna is equal to the distance d_2 from the receiving antenna, which is calculated by the following equation.

(correction) The method of claim 5, The smoothing resolution (?? h) is A method of smoothing a digital terrain model for propagation analysis, characterized by the following equation.

(Where C1 is a variable value that is preferably determined as one of 100 to 400 according to the characteristics of the wireless network design system, and R is a prediction radius)

Images