JP2002016556A - Calculation method for attenuation amount in city and computer-readable recording medium for recording city attenuation calculation program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a calculation method and its recording medium that can estimate attenuation amount by buildings, depending on the utilizing state of lands and its number of households, even when the height data of the buildings are not available, to calculate the attenuation amount in a city. SOLUTION: First, a scale of a city in the direction of a transmission point is obtained from land utilization data from a receiving point to obtain an attenuation by buildings (S1), then the attenuation is compared with a building attenuation obtained from data of number of households, the attenuation, which is the larger, is selected for a maximum attenuation of the building (S2). When a frequency to be checked is a VHF, the maximum building attenuation is halved (S3), a fault distance on a path is obtained, depending on an incident angle onto the receiving point (S4), the maximum building attenuation is corrected by the land use classification and the land form in the fault distance on the radio wave path (S5), and is also corrected by the incident angle (S6), Fresnel loss is calculated (S7) and then finally the city attenuation is calculated (S8).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a calculation method for calculating city attenuation during radio wave propagation and a computer-readable recording medium storing a city attenuation calculation program, and more particularly to land use data and household data. The present invention relates to a method of calculating city attenuation using numerical data and a computer-readable recording medium storing a city attenuation calculation program.

[0002]

2. Description of the Related Art Conventionally, the calculation of city attenuation (propagation attenuation) is based on the notice 64 of Article 7, paragraph 4 of the Radio Station Licensing Procedure Regulations of the Ministry of Posts and Telecommunications
According to No. 0, the average height of a 1 km square surface centered on the receiving point is 1 at a height of 10 meters.
The building density expressed as a percentage of the sum of the horizontal cross-sectional areas of building structures within a square kilometer per square kilometer, and whether the receiving point is an urban area or a suburb, and the angle of incidence of radio waves to the receiving point It has been.

[0003]

However, in such a conventional technique, there is a problem that it is not possible to calculate the amount of city attenuation when there is no height data of the building structure. In addition, in order to determine the urban attenuation at an arbitrary point in the country by the method of Notification 640 of the Ministry of Posts and Telecommunications, it is necessary to determine the height of a building structure of 1 square kilometer square centered on the point. This has the problem that it takes enormous effort (cost) and is not realistic.

[0004] The present invention has been made in view of such a problem, and an object of the present invention is to provide a method for constructing a building based on the state of land use and the number of households even when the height data of the building structure does not exist. It is an object of the present invention to provide a calculation method for estimating the amount of urban attenuation and calculating the amount of urban attenuation based on the estimated amount, and a computer-readable recording medium storing an urban attenuation amount calculation program.

[0005]

According to the present invention, in order to achieve the above object, an invention according to claim 1 is a calculation method for calculating an amount of city attenuation during radio wave propagation. Calculating a building maximum attenuation from a building attenuation obtained from land use data between the receiving point and the building, and a building attenuation obtained from data on the number of households around the receiving point; and Obstruction distance calculated from an elevation angle at which the transmission point is viewed from a point, and obtaining land use data within the obstruction distance, and correcting the building maximum attenuation from the obstruction distance and land use data; Obtaining a building attenuation corresponding to the value of the elevation angle from the building maximum attenuation, and a building attenuation corresponding to the elevation angle,
Adding a Fresnel loss obtained from the obstacle distance and topographical data within the obstacle distance.

According to a second aspect of the present invention, the step of calculating the maximum building attenuation comprises: a building attenuation obtained from land use data between a transmission point and a reception point; This is a step of comparing with the building attenuation obtained from the data on the number of households in the vicinity, and setting the larger one as the maximum building attenuation.

Further, the invention according to claim 3 is characterized in that the step of correcting the maximum amount of building attenuation includes a step of correcting the amount of attenuation based on a difference in frequency used.

[0008] The invention according to claim 4 is a recording medium for recording a calculation program for calculating the amount of city attenuation during radio wave propagation, wherein the recording medium records land use data between a transmission point and a reception point. The step of calculating a building maximum attenuation amount from the obtained building attenuation amount and the building attenuation amount obtained from the number of households around the reception point, and calculating from the elevation angle at which the transmission point is viewed from the reception point. Obstacle distance, determining land use data within the obstacle distance, correcting the building maximum attenuation from the obstacle distance and land use data, the elevation angle value from the corrected building maximum attenuation Calculating a building attenuation amount corresponding to the above, and adding a Fresnel loss obtained from the terrain data within the obstacle distance and the obstacle distance to the building attenuation amount corresponding to the elevation angle. It is recorded a computer-readable recording medium a calculation program to be executed by the computer.

That is, the present invention relates to radio wave propagation calculation,
In particular, it relates to a method of calculating urban attenuation, which accounts for a large part of the calculation. That is, if the electric field strength at a certain receiving point is determined by the transmitting point position (longitude, latitude, sea level), the receiving point position (longitude, latitude, sea level), and the transmitting antenna pattern (horizontal, vertical), the free space electric field strength becomes Although it can be calculated, the actual electric field strength must take into account the topography around the receiving point and the urban attenuation caused by buildings. The present invention obtains the amount of urban attenuation at the receiving point in radio wave propagation from the Geographical Survey Institute's land use numerical map and regional mesh statistical census data. The maximum attenuation of the building is determined from this, and the correction is made based on the number of households based on the regional mesh statistical census data.This is further corrected from the angle of incidence of the radio wave at the receiving point, and the Fresnel loss is added. The amount of attenuation is determined.

[0010] The city attenuation referred to in the present invention does not mean that the propagation path is limited to a city, but can be applied to a general case.

Here, the Geographical Survey Institute Land Use Digital Map is
1/10 subdivision land use data (KS-202-1) in the National Land Numerical Information marketed by the Japan Map Center, which categorizes land use into 15 types per 100m mesh. And converted into numerical data. This gives the land use data.

The regional mesh statistical census data is the first regional block mesh code (nationwide) in the national census regional mesh statistical data sold by the Statistical Information Research and Development Center, and is 1 km. Or 25
For each 0-meter mesh, the population and the number of general households by gender are quantified based on the census. As a result, the data on the number of households can be obtained.

Both are provided by a magnetic recording medium and can be read by a computer.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a flowchart for explaining a method for calculating an urban attenuation amount according to the present invention, and is a flowchart for explaining a method for calculating an urban attenuation amount using land use data and household number data. Hereinafter, each step will be described.

Step 1 (S1): First, a city scale in a direction from a reception point to a transmission point is obtained from land use data to obtain a building attenuation. That is, the house density in front of the reception point is obtained from the land use data, and the basic building attenuation is obtained from the house density.

Step 2 (S2): Next, a building attenuation based on the number of households is obtained. In places where high-rise apartments are densely populated, significant attenuation may occur. Then, the larger one than the building attenuation obtained in step 1 is set as the building maximum attenuation.

Step 3 (S3): Next, when the studied frequency is VHF, the maximum attenuation of the building is set to 1/2. That is, since the amount of attenuation differs depending on the difference in frequency, VHF
In the case of, correction is made so that the amount of attenuation is reduced. According to a plurality of actually measured data, the error is reduced when it is １ ／. This step 3 is correction by frequency.

Step 4 (S4): Next, the obstacle distance on the radio wave path is obtained from the angle of incidence on the receiving point. In other words, if the reception angle of the radio wave is small, the distance affected by the building extends far, so the obstacle distance is determined from the elevation angle (incident angle) at which the transmission point is viewed from the reception point. The obstacle distance increases as the incident angle decreases. If the transmission point is not in line of sight, the "elevation angle of the transmission point from the reception point"
It means “elevation angle at which the radio wave diffraction point near the receiving point is viewed from the receiving point”.

Step 5 (S5): The maximum attenuation of the building is corrected based on the land use classification and the terrain within the obstacle distance on the radio wave path. That is, the maximum building attenuation is corrected based on the land use situation and the terrain within the obstacle distance. If the land ahead is down, the attenuation is less. This step 5 is a correction based on the terrain and land conditions.

Step 6 (S6): The amount of attenuation corresponding to the actual elevation angle is obtained from the maximum amount of building attenuation obtained in step 5.

Step 7 (S7): Fresnel loss calculation (horizontal maximum 6 dB) is performed. That is, since the radio wave is attenuated by the ground according to the reception incident angle, the loss due to the incident angle (Fresnel loss) is calculated.

Step 8 (S8): The city attenuation is calculated. That is, the calculation is made as follows: city attenuation = building attenuation (S6) + Fresnel loss.

Next, each of the above steps will be described in more detail.

(1) How to Obtain Building Attenuation As shown in FIG. 2, a 100 m mesh is obtained at a distance of 1 km every 125 m from the reception point to the transmission point, 15 degrees left and right and 30 degrees left and right. The land use classification is acquired from the land use data, and the number of data for building land and the number of data for fields and fields are counted.

The attenuation of the building is set to ((number of data of building land− (number of data of field or field / 2)) − 5) / 2 [dB] (0 in case of negative). Since the number of data items is 8 × 5 = 40, the maximum is (40−5) /2=17.5 dB.

(2) Method of Determining Attenuation of Building Based on Number of Households The amount of attenuation is determined as follows from the number of households of one square kilometer around the receiving point.

Attenuation by the number of households = number of households / 500 [dB] Compared with the value obtained from the land use in (1) above, the larger one is set as the maximum attenuation of the building.

(3) Correction of the maximum attenuation of the building in the case of the VHF band The VHF band is set to 減 衰 of the attenuation by the number of households (10 dB at maximum).

(4) Obtaining Obstacle Distance on Radio Wave Path Based on Incident Angle at Receiving Point The elevation angle of the transmitting point (the last diffraction point in the case of a diffracted wave) as viewed from the receiving point is calculated and is affected by the angle. Obtain the obstacle distance and express it as the number of sample points (n) where 125 m is 1.

If the elevation angle is greater than 0.16 rad (about 9 degrees), the obstacle distance is 125 m (the number of sample points n
= 1).

If it is less than 0.16 rad and larger than 0.14 rad, the length is 250 m (the number of sample points n = 2).

If it is 0.14 rad or less and larger than 0.12 rad, it is 375 m (the number of sample points n = 3).・ ・ If less than 0.02 rad (about 1 degree), 1 km (n = 8)
And

(5) The maximum attenuation of a building is corrected based on the terrain up to the obstacle distance on the radio wave path and the land use classification.

When the front of the receiving point is immediately descending like a cliff, the maximum attenuation of the building is naturally reduced. In addition, when the land use is other than building, it is judged that the prospect is good and the correction is made.

The number of points (p: 9 at the maximum) of the sample land up to the obstacle distance calculated in the above (4), including the land use classification at the receiving point, which is more than 4 m from the receiving point and the terrain is not lowered ) And correct the maximum attenuation by the following equation.

The corrected maximum building attenuation = the maximum building attenuation × (p ÷ (n + 1)) [dB] In other words, if the land in front is flat, no correction is performed.

Next, an example of calculating the maximum attenuation of a building will be described with reference to FIG. In FIG. 3, reference numeral 1 denotes a building site, 2 denotes a field, and 3, 4, and 5 denote building sites. Assuming that the elevation angle desired for the transmission point is 0.09 rad, the obstacle distance is 625 m (n = 5) from the above (4). If the terrain data and land use data are as described above, the difference is 4m from the receiving point
The following points are 4 points, of which the building site is 3
Therefore, if the maximum building attenuation is 20 dB, the maximum building attenuation after correction = 20 × (3 ÷ (5+
1)) = 10 [dB].

(6) Correction of Building Maximum Attenuation by Elevation Angle (Reception Incident Angle) In order to convert the building attenuation to the elevation corresponding to the elevation angle, the corrected building maximum attenuation obtained in (5) above is used. And elevation angle 0.00
The elevation angle is corrected so that it becomes the maximum attenuation at 5 rad and becomes 0 at 1 rad.

Building attenuation = (Maximum building attenuation− (Maximum building attenuation ÷ 2.301) × (Log (elevation angle) +
2.301))-(Maximum Building Attenuation- (Maximum Building Attenuation × 2.301) × (Log (1.0) +2.30)
1)) However, 0.005 <elevation angle <1 [rad]

(7) Calculation of Fresnel Loss When a radio wave from a transmission point enters from an elevation angle of 0 degree (horizontal), half of the Fresnel is lost due to the ground, and the loss is 6 dB. Naturally, as the incident angle increases, the Fresnel loss due to the ground decreases. In the calculation, first, the maximum Fresnel loss is obtained from the terrain data on the radio wave path, and corrected by the incident angle.

The maximum Fresnel loss is calculated by the following formula by calculating the number of points (p: 9 at maximum) where the terrain is not lowered by 4 m or more from the receiving point at the sample points up to the obstacle distance obtained in (4) above. .

Maximum loss = 6 × (p ÷ (n + 1)) [dB] The Fresnel loss is equal to an elevation angle of 0 if the front is a water surface in the UHF band.
Linear interpolation is performed by the incident angle so that the maximum loss is obtained at 005 rad and 0 at an elevation angle of 0.02 rad. Fresnel loss = (maximum loss-(maximum loss / 0.602) x (Log
(Elevation angle) +0.602)) − (Maximum loss− (Maximum loss ÷ 0.602) × (Lo
g (0.02) +0.602)) However, 0.005 <elevation angle <0.02 [rad] If the VHF band or the front is other than the water surface, linear interpolation is performed by the incident angle so that the maximum loss is obtained at the elevation angle of 0.005rad and becomes 0 at the elevation angle of 0.2rad. Then, it is obtained by the following equation. Fresnel loss = (maximum loss-(maximum loss ÷ 1.602) x (Log
(Elevation angle) + 1.602))-(Maximum loss-(Maximum loss ÷ 1.602) x (L
og (0.2) +1.602)) However: 0.005 <elevation angle <0.2 [rad]

(8) Calculation of Urban Attenuation The urban attenuation is calculated by the following equation by adding the Fresnel loss to the building attenuation corresponding to the elevation angle obtained in (6) above.

Urban attenuation = Loss due to building + Fresnel loss As described above, the method for calculating urban attenuation according to the present invention takes into account the city size, topography, and land use situation in front, and was used in the calculation. Various parameters are optimized values based on actual measurement values.

As described above, according to the method for calculating the amount of urban attenuation according to the present invention, even when height data of a building structure does not exist, the amount of attenuation due to a building is estimated from the use of land and the number of households. Thus, the city attenuation can be calculated.

The above-described embodiments of the present invention can be implemented using a computer as follows. The map data of the area including the transmission point and the reception point, mesh land use data including these points, and mesh household number data are stored in the memory of the computer.
Then, by inputting the longitude and latitude of the transmission point and the reception point with the input device of the computer, or by pointing the transmission point and the position of the reception point on the map display screen, the transmission point in the map data, The position of the receiving point can be determined. Since the map data includes elevation data, it is possible to determine a profile that connects transmission and reception points, an elevation angle, and a profile that connects arbitrary points. Further, since the land use classification and the number of households around the receiving point can be read by the mesh value, all parameters necessary for calculating the city attenuation can be extracted or calculated. Thus, the calculation of the above-described steps can be executed by a computer.

[0047]

As described above, according to the present invention, there is provided a calculation method for calculating the amount of city attenuation during radio wave propagation, the method comprising calculating a building attenuation obtained from land use data between a transmission point and a reception point. Calculating the maximum building attenuation from the amount and the building attenuation obtained from the number of households around the receiving point, and the obstacle distance calculated from the elevation angle at which the transmission point is viewed from the receiving point, and within the obstacle distance Obtaining land use data and correcting the maximum building attenuation from the obstacle distance and the land use data; obtaining the building attenuation corresponding to the elevation angle from the corrected maximum building attenuation; and And adding a Fresnel loss obtained from the obstacle distance and the terrain data within the obstacle distance to the building attenuation corresponding to the above, the conventional method of the Ministry of Posts and Telecommunications Notification No. 640,
It is necessary to calculate the height of a building structure of 1 square kilometer square centering on that point, as in the case of calculating the urban attenuation at any point in the country, which requires enormous labor (cost). What was not realistic was resolved. In addition, by using the calculation method of the city attenuation amount of the present invention, it is possible to calculate the city attenuation amount at an arbitrary point in Japan by using commercially available electronic data.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a method of calculating an urban attenuation according to the present invention.

FIG. 2 is a diagram for explaining a method of obtaining a building maximum attenuation.

FIG. 3 is a diagram for explaining an example of calculation for correcting the maximum building attenuation based on the terrain and the land use classification up to the obstacle distance on the radio wave path.

[Explanation of symbols]

 1,3,4,5 Building land 2 fields

Claims (4)

[Claims] 1. A method for calculating city attenuation during radio wave propagation, comprising: a building attenuation obtained from land use data between a transmission point and a reception point; and a number of households around the reception point. Calculating the building maximum attenuation from the building attenuation obtained from the data, and the obstacle distance calculated from the elevation angle at which the transmission point is viewed from the reception point, and obtaining land use data within the obstacle distance,
Correcting the building maximum attenuation from the obstacle distance and the land use data; obtaining a building attenuation corresponding to the elevation angle from the corrected building maximum attenuation; and Adding a Fresnel loss obtained from the obstacle distance and topographical data within the obstacle distance to a corresponding building attenuation amount, the method for calculating an urban attenuation amount. 2. The step of calculating the maximum building attenuation includes determining the building attenuation obtained from land use data between a transmission point and a reception point and data on the number of households around the reception point. The method for calculating an urban attenuation according to claim 1, wherein the step of comparing the amount of attenuation with the building is a step of setting the larger one as the maximum attenuation of the building. 3. The method according to claim 1, wherein the step of correcting the maximum building attenuation includes the step of correcting the attenuation according to a difference in a used frequency. 4. A recording medium for recording a calculation program for calculating a city attenuation during radio wave propagation, wherein the building attenuation obtained from land use data between a transmission point and a reception point is obtained. Calculating the building maximum attenuation from the building attenuation obtained from the number of households around the receiving point, and the obstacle distance calculated from the elevation angle of viewing the transmission point from the receiving point, and within the obstacle distance Ask for land use data,
Correcting the building maximum attenuation from the obstacle distance and the land use data; obtaining a building attenuation corresponding to the elevation angle from the corrected building maximum attenuation; and A computer-readable recording medium recording a calculation program for causing a computer to execute the obstacle distance and a step of adding a Fresnel loss obtained from terrain data within the obstacle distance to a corresponding amount of building attenuation.