JP5699544B2 - Radio wave propagation characteristic estimation system, radio wave propagation characteristic estimation method, and computer program - Google Patents

Description

  The present invention relates to a radio wave propagation characteristic estimation system, a radio wave propagation characteristic estimation method, and a computer program.

  The estimation of radio wave propagation characteristics is important when performing area design and interference estimation of a wireless communication system.

  For example, in a mobile communication system, radio base stations are arranged so that a communication service can be maintained even when a mobile station moves, and a radio service area is continuously formed. At this time, by estimating the radio wave propagation characteristics, areas where radio waves cannot be received due to the influence of topography, features, etc. are identified, and radio parameters (transmission power, antennas) of the radio base station are set so that such areas do not exist. Tuning of directivity, antenna tilt angle, etc. is performed.

  Another example of estimating the radio wave propagation characteristics is a wireless system that performs communication by sharing that frequency when the existing wireless system does not use its assigned frequency spatially and temporally. There is a cognitive radio system. In a cognitive radio system, communication is performed by sharing a frequency within a range in which interference with an existing radio system due to own transmission does not affect an existing service. At this time, the radio wave propagation characteristic is estimated in order to estimate how much interference is caused to the existing wireless system by the transmission of the cognitive wireless system.

  The radio wave propagation characteristic is generally estimated by using a propagation estimation formula. Examples of the propagation estimation formula include Okumura and Kashiwa formulas, ITU-R (International Telecommunication Union Radiocommunications Sector), p. Various propagation estimation formulas such as the 1546 model (see Non-Patent Document 1) are known. However, no matter what type of propagation estimation formula is used, there are not a few errors due to the effects of topography and features in the area where the radio wave propagation characteristics are actually estimated, modeling errors in the propagation estimation formula, and the like.

  Measurement correction is known as a method for reducing such an estimation error (propagation estimation error) of the propagation estimation formula. For example, in the technique described in Patent Document 1, first, a running test is performed in an area where radio wave propagation characteristics are estimated, and a radio wave reception level is measured to obtain an actual measurement value. Next, parameters of the propagation estimation formula (surrounding feature height, distance attenuation coefficient, constant term) are set so that the error between the measured value of the reception level obtained in the running test and the reception level calculated using the propagation estimation formula becomes small. Etc.) is corrected. The actual measurement value used at this time is limited to measurement data within a predetermined distance from the transmission point (wireless base station). As a result, the distance from the transmission point is so far away that the influence of the actual measurement value obtained at the measurement point with a different propagation environment is excluded from the position where the propagation loss is estimated (evaluated) (hereinafter referred to as the evaluation point). Thus, the propagation estimation formula is actually corrected.

  As another actual measurement correction method, Patent Document 2 describes a method in which an actual measurement value is weighted according to the distance between the propagation loss evaluation point and the measurement point and reflected in the correction of the parameter of the propagation estimation formula.

JP 2005-229453 A JP 2005-223732 A

ITU-R, Method for Point to area prediction for terrestrial services in the frequency range, 30 MHz to 3000 MHz, ITU-R P. 1546-3, 2007.

  However, in the case of the actual measurement correction technique described in Patent Document 1, there are concerns about the following problems. Even when the measurement point is within a predetermined distance from the transmission point, the distance between the measurement point and the evaluation point is not necessarily close (for example, in an extreme case, the measurement point has an evaluation point across the transmission point). Etc.). When the evaluation point and the measurement point are separated from each other, the similarity of the propagation environment (propagation loss) is reduced, so that the accuracy of the actual measurement correction may be reduced.

  On the other hand, in Patent Document 2, since the actual measurement value is weighted according to the distance between the evaluation point of the propagation loss and the measurement point, and the actual measurement correction is performed. The influence of the acquired measurement data can be suppressed. This is based on the property that the similarity of the propagation environment between the evaluation point and the measurement point changes with the distance between the evaluation point and the measurement point. However, on the other hand, the similarity of the propagation environment changes according to the surrounding environment (for example, an urban area or a mountain area) even if the distance is the same. In the case of the actual measurement correction technique described in Patent Literature 2, there is a possibility that actual measurement correction using an inappropriate weight may be performed depending on the surrounding environment, which causes a reduction in correction accuracy.

  The present invention has been made to solve the above-described problem, and an object thereof is to provide a radio wave propagation characteristic estimation system, a radio wave propagation characteristic estimation method, and a computer program capable of improving the accuracy of measurement correction. To do.

  The radio wave propagation characteristic estimation system according to the present invention includes a reception level estimation value of a radio wave transmitted from a transmission point of a transmission station at an arbitrary evaluation point within an evaluation area for estimating the radio wave propagation characteristic. A system that performs actual measurement correction using an actual level measurement value, the propagation estimation unit calculating a reception level estimation value at the evaluation point using a predetermined propagation estimation formula, and the evaluation of radio waves transmitted from the transmission point An actual measurement correction unit that actually corrects the reception level estimation value based on the reliability indicating the relationship between the propagation loss at the point and the propagation loss at the measurement point; the positional relationship between the evaluation point, the transmission point, and the measurement point; An area attribute-specific reliability calculating unit that calculates the reliability based on area attribute information.

  In addition, the radio wave propagation characteristic estimation system of the present invention measures the reception level estimation value of a radio wave transmitted from a transmission point of a transmission station at a measurement point at an arbitrary evaluation point within an evaluation area for estimating the radio wave propagation characteristic. A measurement correction using the received reception actual measurement value, a propagation estimation unit that calculates a reception level estimation value at the evaluation point using a predetermined propagation estimation formula, and a radio wave transmitted from the transmission point, Based on the reliability indicating the relationship between the propagation loss at the evaluation point and the propagation loss at the measurement point, an actual measurement correction unit that actually corrects the reception level estimation value, and a distance between the evaluation point and the measurement point; And a reliability calculation unit that calculates the reliability based on the relationship between the path loss error at the evaluation point and the correlation distance between the path loss error at the measurement point.

  The radio wave propagation characteristic estimation method of the present invention is a reception in which an estimated reception level of a radio wave transmitted from a transmission point of a transmission station is measured at a measurement point at an arbitrary evaluation point within an evaluation area for estimating the radio wave propagation characteristic. A method of performing actual measurement correction using an actual level measurement value, wherein a reception level estimation value at the evaluation point is calculated using a predetermined propagation estimation formula, and a propagation loss at the evaluation point of a radio wave transmitted from the transmission point And based on the reliability indicating the relationship between the propagation loss at the measurement point, the received level estimation value is actually corrected, and the reliability is determined based on the positional relationship between the evaluation point, the transmission point, and the measurement point, and area attribute information. Calculate based on

  The computer program of the present invention is an actual reception level measurement value obtained by measuring an estimated reception level of a radio wave transmitted from a transmission point of a transmission station at an arbitrary evaluation point within an evaluation area for estimating a radio wave propagation characteristic. Is a computer program that performs actual measurement correction using a calculation process for calculating a reception level estimation value at the evaluation point using a predetermined propagation estimation formula, and a propagation loss at the evaluation point of radio waves transmitted from the transmission point. And a process of actually correcting the reception level estimation value based on the reliability indicating the relationship between the propagation loss at the measurement point, the reliability, the positional relationship between the evaluation point, the transmission point, and the measurement point, and the area The computer calculates a process based on the attribute information.

  According to the present invention, it is possible to improve the accuracy of actual measurement correction.

It is a block diagram which shows the structural example of the radio wave propagation characteristic estimation system which concerns on the 1st Embodiment of this invention. It is a table | surface which shows an example of the relationship between comprehensive area attribute information and a measurement reliability function in 1st Embodiment. It is a figure explaining the evaluation area in the 2nd Embodiment of this invention, and is a figure explaining the distance between measurement-evaluation in an evaluation area especially. It is a block diagram which shows the structural example of the electromagnetic wave propagation characteristic estimation system which concerns on 2nd Embodiment. It is a table | surface which shows an example of the relationship between comprehensive area attribute information and correlation distance in 2nd Embodiment. 6 is a flowchart for explaining an operation example of the radio wave propagation characteristic estimation system shown in FIG. 4. It is a figure explaining the evaluation area in the 3rd Embodiment of this invention, and is a figure explaining the angle between measurement-evaluation in an evaluation area especially. It is a table | surface which shows an example of the relationship between each function of comprehensive area attribute information and path loss error angle correlation in 3rd Embodiment. FIG. 9 is a graph showing a function of each path loss error angle correlation in FIG. 8. FIG. It is a conceptual diagram of the 4th Embodiment of this invention, and is a figure which shows an example of the relationship between each measurement point and evaluation point on a road in detail. It is a table | surface which shows an example of the correlation distance in the path loss error correlation according to comprehensive area attribute information hold | maintained by the parameter storage part according to comprehensive area attribute in 4th Embodiment. It is a figure explaining the evaluation area in the 5th Embodiment of this invention, and is a figure which shows the state in which a several measurement point exists in an evaluation area in detail. It is a block diagram of the radio | wireless communications system of the 6th Embodiment of this invention. It is a block diagram which shows the structural example of the secondary system shown in FIG. It is a flowchart for demonstrating the operation example (mainly operation example regarding interference level calculation) of the spectrum manager shown in FIG.

[First Embodiment]
FIG. 1 is a block diagram showing a configuration example of a radio wave propagation characteristic estimation system 100 according to the first embodiment of the present invention. The radio wave propagation characteristic estimation system 100 includes a propagation estimation unit 101, a comprehensive area attribute-specific reliability calculation unit 102, and an actual measurement correction unit 103.

  The propagation estimation unit 101 includes information on a transmission station (transmission point) that transmits a radio wave that is an object of radio wave propagation characteristic estimation (hereinafter referred to as “transmission point information”), and an arbitrary area within an evaluation area that estimates the radio wave propagation characteristic. Enter evaluation point information (hereinafter, “evaluation point information”).

  Here, the evaluation point information includes position information of the evaluation point (for example, coordinate information including latitude and longitude), an assumed receiving antenna height, an assumed receiving antenna gain, or area attribute information of the evaluation point. The area attribute information can be manually determined in advance for each evaluation point, or can be determined using map data (for example, data holding feature heights for each latitude and longitude). Is possible. Note that the evaluation point information does not always need to include all the information.

  The transmission point information includes position information of a transmission station (transmission point), transmission power, transmission antenna gain, transmission antenna height, or area attribute information of the transmission point. The area attribute information can be determined manually for each transmission point in advance, or can be determined using map data (for example, data holding the height of a feature for each latitude / longitude). Is possible. The transmission point information does not always need to include all the above information.

  The propagation estimation unit 101 calculates a reception level estimation value at the evaluation point using a predetermined propagation estimation formula (for example, a propagation estimation formula such as the Okumura-Kashiwa formula or the ITU-RP P.1546 model). Specifically, the propagation estimation unit 101 is assumed to receive the radio wave at the evaluation point, the gain including the transmission power at the transmitting station and the directivity of the transmission antenna, the estimated value of the propagation loss calculated by the propagation estimation formula, and the evaluation point. The reception level estimation value at the evaluation point is calculated using the reception antenna gain. The reception level estimated value at the evaluation point calculated by the propagation estimating unit 101 is output to the actual measurement correcting unit 103.

  The total area attribute-specific reliability calculation unit 102 inputs measurement data in addition to the above-described evaluation point information and transmission point information.

  Here, the measurement data includes an actual reception level value, measurement point information (measurement position, measurement antenna height, measurement antenna gain, etc.), or area attribute information of the measurement point. The measurement position can be coordinate information represented by latitude and longitude, for example. The area attribute information can be manually determined for each measurement point in advance, or can be determined using map data (for example, data holding feature heights for each latitude and longitude). Is possible. Note that the measurement data need not always include all of the above information.

  Normally, information on radio wave-specific identification codes (for example, scrambling codes assigned to each transmitting station (base station)) can be obtained by measuring radio waves. Furthermore, it is necessary to grasp from which transmitting station the identification code is transmitted. For example, if transmitting station data representing an identification code to be used is held as transmitting station information, it becomes possible to specify which transmitting station's signal reception level the measurement data represents. Therefore, in the present embodiment, for the sake of clarity, as described above, the transmission station that is the object of radio wave propagation characteristic estimation and the measurement data are already associated with each other using the identification code and the transmission station data. It is assumed that the measurement data is used for the actual measurement correction.

  The total area attribute-specific reliability calculation unit 102 is used when the reception level estimation value at the evaluation point calculated by the propagation estimation unit 101 is actually measured and corrected using the reception level actual value acquired by a running test or the like. The reliability of the level measurement value (hereinafter referred to as “measurement reliability”) is calculated. The measurement reliability is essentially the relationship between the propagation loss at the evaluation point and the propagation loss at the measurement point of the transmission wave from the transmission point (for example, the correlation of the path loss error described in the second and subsequent embodiments). It represents. And this measurement reliability becomes weight information which shows the effectiveness with respect to the evaluation point of a reception level actual value. A function that receives the positional relationship (for example, coordinate information of each point) between the measurement point, the evaluation point, and the transmission point and outputs the measurement reliability according to the positional relationship is hereinafter referred to as a measurement reliability function.

  The total area attribute-specific reliability calculation unit 102 determines a measurement reliability function. The total area attribute-specific reliability calculation unit 102 calculates the function based on the “total area attribute information” determined comprehensively based on the positional relationship between each point (evaluation point, transmission point, and measurement point) and the area attribute information. A predetermined calculation parameter is determined (in other words, a measurement reliability function is determined). The total area attribute-specific reliability calculation unit 102 outputs the measurement reliability output from the measurement reliability function determined according to the total area attribute information to the actual measurement correction unit 103.

  FIG. 2 is a table showing an example of the relationship between the comprehensive area attribute information and the measurement reliability function in the first embodiment. Here, as an example, a case where urban areas, suburban areas, and mountainous areas indicating an area environment are used as the comprehensive area attribute information, and measurement reliability functions f1, f2, and f3 are assigned to the respective areas. Here, the measurement reliability functions f1, f2, and f3 are all functions for calculating measurement reliability (relationship between propagation loss at the evaluation point and propagation loss at the measurement point) according to the positional relationship between the points. As described above, since the calculation parameters are different, different calculation results (that is, measurement reliability) are output even when the same positional relationship is input. For example, when the comprehensive area attribute information is a suburban area, the comprehensive area attribute-specific reliability calculation unit 102 selects the measurement reliability function f2.

  Here, some examples of the method for determining the comprehensive area attribute information are given below.

  For example, the total area attribute-specific reliability calculation unit 102 can set “total area attribute information” as a result of comprehensively determining each area attribute information of a plurality of points (for example, measurement points and evaluation points).

  Alternatively, the comprehensive area attribute-specific reliability calculation unit 102 can set the area attribute at any one of the points as “total area attribute information”. For example, if it is determined that there is no need to consider other than the area attribute information of the measurement point, only the area attribute information of the measurement point is used (that is, the area attribute information of the measurement point is set as the comprehensive area attribute information). You can also. In this case, since the area attribute information of the evaluation point and the transmission point is unnecessary, it is not necessary to include the area attribute information of each point in the evaluation point information and the transmission point information. Of course, only the area attribute information of the evaluation point or only the area attribute information of the transmission point can be used as the comprehensive area attribute information.

  The actual measurement correction unit 103 uses the reception level estimation value at the evaluation point input from the propagation estimation unit 101, the measurement reliability input from the total area attribute-specific reliability calculation unit 102, and the reception level actual measurement value. Then, the reception level estimation value is corrected by actual measurement. When the measurement reliability is high, the actual measurement correction method performs a correction that largely reflects the reception level actual measurement value with respect to the reception level estimation value, and when the measurement reliability is low, Make corrections to reflect small. The reception level after actual measurement correction obtained in this way is output to the outside.

  According to the first embodiment described above, when the reception level estimated value at the evaluation point is actually corrected, the effectiveness of the reception level actual value used for the actual measurement correction is determined based on the positional relationship between the measurement point, the evaluation point, and the transmission point. Therefore, effective measurement correction can be performed.

  Moreover, the measurement reliability is determined in consideration of the area attribute information of at least one of the evaluation point, the transmission point, and the measurement point, so that an appropriate reliability can be set according to the surrounding environment. Thus, highly accurate measurement correction can be performed.

  In the first embodiment described above, the area environment (urban area, suburban area, mountainous area) is used as the area attribute information, but the area attribute information is not limited to this. Other area attribute information can also be used.

[Second Embodiment]
FIG. 3 is a diagram illustrating the evaluation area 10 according to the second embodiment of the present invention, and in particular, is a diagram illustrating the measurement-evaluation distance in the evaluation area 10. In the evaluation area 10, a transmission point 12 that is a position of a transmission station 11 that transmits a radio wave that is an object of estimation of radio wave propagation characteristics, an evaluation point 13 that is an object point of which a reception level is estimated, and reception used in actual measurement correction. There is a measurement point 14 that is a point at which the actual level measurement value is measured. Here, the distance from the measurement point 14 to the evaluation point 13 is defined as a measurement-evaluation distance d.

  In the present embodiment, for the purpose of estimating the reception level at the evaluation point 13, the reception level estimation value calculated at the measurement point 14 is used as the reception level estimation value calculated at the measurement point 14 as the means. A radio wave propagation characteristic estimation system that uses actual measurement correction will be described.

  FIG. 4 is a block diagram illustrating a configuration example of the radio wave propagation characteristic estimation system 200 according to the present embodiment. The radio wave propagation characteristic estimation system 200 includes a propagation estimation unit 202, a measurement data determination unit 203, a measurement data storage unit 204, a reliability calculation unit 205, an overall area attribute-specific parameter storage unit 206, and an actual measurement correction unit 207. .

  The radio wave propagation characteristic estimation system 200 includes evaluation point information (position information, assumed antenna height, assumed antenna gain, etc.) regarding an evaluation point that is an arbitrary point in the evaluation area 10 and is a target point for estimating the reception level. Entered. This evaluation point information is input to the propagation estimation unit 202, the measurement data determination unit 203, and the reliability calculation unit 205. In the present embodiment, the evaluation score is, for example, the evaluation score 13 in FIG.

  The measurement data determination unit 203 determines measurement data used for actual measurement correction based on the input evaluation point information. The measurement data includes an actual value of the reception level, measurement point information (measurement position, measurement antenna height, measurement antenna gain, etc.), and measurement point area attribute information. Measurement data is held in the measurement data storage unit 204. The measurement data determination unit 203 acquires measurement data from the measurement data storage unit 204. For example, when there are a plurality of measurement data, it is possible to select a measurement point having the closest distance from the input evaluation point. In the present embodiment, the measurement data at the measurement point 14 is used as the measurement data. The measurement data determination unit 203 outputs the acquired measurement data to the propagation estimation unit 202, the reliability calculation unit 205, and the actual measurement correction unit 207.

  The propagation estimation unit 202 inputs the evaluation point information regarding the evaluation point 13 and the measurement data at the measurement point 14 output from the measurement data determination unit 203. The propagation estimation unit 202 calculates the reception level estimation value at each of the evaluation point 13 and the measurement point 14 using a predetermined propagation estimation formula.

  Specifically, the propagation estimator 202 calculates the distance between the evaluation point 13 and the transmission point 12, and the propagation loss at this distance is calculated using a predetermined propagation estimation equation (for example, Okumura-Hagi equation or ITU-RP. (Propagation estimation formula such as 1546 model). The propagation estimation unit 202 evaluates using the propagation loss, the transmission power of the transmission station 11, the antenna gain including the directivity of the transmission antenna, and the reception antenna gain assumed to receive the radio wave at the evaluation point 13. A reception level estimation value at point 13 is calculated. In addition, the propagation estimation unit 202 calculates the distance between the measurement point 14 and the transmission point 12, and calculates the propagation loss at this distance using the above propagation estimation formula. The propagation estimation unit 202 uses the propagation loss, the transmission power of the transmission station 11, the antenna gain including the directivity of the transmission antenna, and the reception antenna gain at the time of actual measurement at the measurement point 14. The reception level estimation value at is calculated.

  The reception level estimation values obtained at the evaluation points 13 and the measurement points 14 are input to the actual measurement correction unit 207.

  The reliability calculation unit 205 is an actual reception level value used when the reception level estimation value at the evaluation point 13 calculated by the propagation estimation unit 202 is measured and corrected using the reception level actual value acquired by a running test or the like. The measurement reliability is calculated. Regarding the calculation of the measurement reliability, the reliability calculation unit 205 inputs the evaluation point information regarding the evaluation point 13 and the measurement data at the measurement point 14 output from the measurement data determination unit 203. The reliability calculation unit 205 calculates the distance between measurement and evaluation (denoted as d in FIG. 3) from the measurement point 14 to the evaluation point 13 calculated based on the position information of the evaluation point information and the position information of the measurement data. Based on the comprehensive area attribute information, the measurement reliability for the evaluation point 13 of the measurement data is calculated.

  The measurement reliability used in this embodiment is the path loss error that is the difference between the actual reception level at the evaluation point 13 and the reception level estimation value calculated using the propagation estimation formula, and the actual reception level (measurement at the measurement point 14). In the case of the point 14, it corresponds to an actual measurement value) and a path loss error correlation which is a correlation value between a path loss error which is a difference between the reception level estimation value calculated using the propagation estimation formula is used. As a property of the path loss error correlation, for example, when the path loss error correlation is high (close to 1), if the path loss error at the measurement point 14 is +2 dB, for example, the path loss error at the evaluation point 13 may be about +2 dB. Becomes higher. Conversely, when the path loss error correlation is low (close to 0), just because the path loss error at the measurement point 14 is +2 dB, the path loss error at the evaluation point 13 is not always +2 dB.

This path loss error correlation is a value that depends on the measurement-evaluation distance d. When d is small, the similarity between the surrounding environment of the measurement point 14 and the surrounding environment of the evaluation point 13 (that is, the similarity of propagation loss). ) Increases, the path loss error correlation increases. Conversely, when d is large, the path loss error correlation decreases. In the present embodiment, this path loss error correlation ρ (d) is calculated using the exponential correlation of equation (1).

In (Expression 1), d _corr is a correlation distance, and is a distance between measurement and evaluation when the path loss error correlation is 0.5. The correlation distance d _corr is a value determined according to the surrounding environment (area attribute).

FIG. 5 is a table showing an example of the relationship between the comprehensive area attribute information and the correlation distance d _corr in the second embodiment. Here, in this embodiment, the case where the comprehensive area attribute information is the area attribute information of the measurement point 14 is taken as an example. Further, in the present embodiment, as an example, the case where the area attribute information is an area environment (three areas of an urban area, a suburban area, and a mountain area) is shown. In FIG. 5, the correlation distance d _corr in each area environment is d1, d2, and d3 in the urban area, suburban area, and mountainous area, respectively. As specific examples of the correlation distance, values such as d1 = 150 m, d2 = 200 m, and d3 = 300 m are used. For example, in a mountainous area, since the propagation loss is affected by the undulations of mountains and land, the propagation loss varies gradually with distance, and as a result, the path loss error also varies gradually with distance. On the other hand, in urban areas, the propagation loss is often determined by the influence of buildings, so that the propagation loss is likely to fluctuate even at a short distance, and as a result, the path loss error is likely to fluctuate at a short distance.

The table shown in FIG. 5 is held in the comprehensive area attribute-specific parameter storage unit 206 as table data. Note that this correlation distance d _corr may vary depending on the propagation estimation formula. Therefore, when using a plurality of propagation estimation formulas, the correlation distance d _corr corresponding to each is calculated by the parameter storage unit 206 for each area attribute. It is preferable to hold.

The reliability calculation unit 205 acquires an appropriate correlation distance d _corr according to the total area attribute information (in this embodiment, the area attribute information of the measurement point 14) from the total area attribute-specific parameter storage unit 206. By using the correlation distance d _corr and the measurement-evaluation distance d, the path loss error correlation ρ (d) is calculated by the equation (1), and this is used as the measurement reliability. The measurement reliability thus obtained is output to the actual measurement correction unit 207.

The actual measurement correction unit 207 inputs the reception level estimation value at the evaluation point 13 (hereinafter referred to as E _T ) and the reception level estimation value at the measurement point 14 (hereinafter referred to as E _M ) from the propagation estimation unit 202. Further, the measured correction unit 207, the measurement data determining unit 203 measurement data (hereinafter, the reception level measured value of this to R _M) from the type a, the measurement for the evaluation point 13 of the measurement data from the reliability calculation unit 205 Enter the reliability (hereinafter referred to as w). Found correction unit 207, using these, the reception level estimate E _T of the evaluation points 13 determined by the propagation estimation equation to the measured corrected by (Equation 2).

In (Equation 2), _{C T} represents the reception level after the measured corrected at the evaluation point 13. (Expression 2) multiplies the path loss error (R _M −E _M ) at the measurement point 14 by the measurement reliability w as a weight to correct the reception level estimation value E _T. Reception level C _T after the measured corrected at the evaluation point 13 thus obtained is output.

In the above description, the measurement reliability w in (Expression 2) is the path loss error correlation ρ (d) (that is, w = ρ (d)). For this measurement reliability w, it is also possible to take into account a measurement error when actually measuring the reception level at the measurement point 14. Here, the measurement error is a statistical error generated due to the influence of thermal noise or the like included in the measurement. In accordance with the magnitude of the measurement error, the deviation between the actual received level value and the true received level value increases, and the accuracy of the actual measurement correction deteriorates. In order to take into account the influence of the measurement error, if the variance of the measurement error of the reception level actual measurement value at the measurement point 14 is σ _M ² and the variance of the path loss error in the propagation estimation formula is σ _L ² , the measurement is performed. The reliability can be given by (Equation 3).

  In (Equation 3), the measurement reliability is determined based on the balance between the measurement error of the reception level actual measurement value and the path loss error. The measurement reliability defined by (Equation 3) approaches the path loss error correlation when the measurement error is sufficiently low compared to the path loss error. On the other hand, when the measurement error is sufficiently high compared to the path loss error, the path loss error correlation is obtained. Smaller than

  FIG. 6 is a flowchart for explaining an operation example of the radio wave propagation characteristic estimation system 200 shown in FIG. In the following description, FIGS. 3 to 5 are referred to as necessary.

  First, the position of the evaluation point 13 that is the target for estimating the reception level in the evaluation area 10 for estimating the radio wave propagation characteristics is input (step S10). Next, the measurement point 14 used for the actual correction of the reception level at the evaluation point 13 is determined (step S11). The propagation estimation unit 202 calculates the reception level estimation value at each of the evaluation point 13 and the measurement point 14 using a predetermined propagation estimation formula (step S12). Specifically, the reception level estimation value at the evaluation point 13 is an antenna gain including the propagation loss according to the distance between the evaluation point 13 and the transmission point 12, the transmission power of the transmission station 11, and the directivity of the transmission antenna. And the receiving antenna gain assumed for radio wave reception at the evaluation point 13. On the other hand, the reception level estimated value at the measurement point 14 is measured by the propagation loss according to the distance between the measurement point 14 and the transmission point 12, the transmission power of the transmission station 11, the antenna gain including the directivity of the transmission antenna, and the measurement. It is calculated using the receiving antenna gain at the time of actual measurement at the point 14.

The reliability calculation unit 205 calculates the measurement reliability of the measurement data for the evaluation point 13 (step S13). Specifically, the reliability calculation unit 205 calculates the correlation distance d _corr according to the comprehensive area attribute information (for example, area attribute information of the measurement point 14) and the measurement-evaluation distance d from the measurement point 14 to the evaluation point 13. And the path loss error correlation ρ (d) obtained by (Equation 1) using

As shown in the above (Equation 2), the actual measurement correcting unit 207 adds the measurement reliability w (for example, w) to the path loss error (the error between the reception level actual measurement value R _M and the reception level estimation value E _M ) at the measurement point 14. = path loss error correlation ρ a value obtained by multiplying the (d)) as a correction value to correct the reception level estimate E _T at the evaluation point 13 (step S14).

  In the second embodiment described above, based on the distance from the measurement point to the evaluation point, a path loss error correlation that is a correlation between the path loss error at the measurement point and the path loss error at the evaluation point is calculated, and this is calculated as the measurement reliability. To do. Then, using this measurement reliability, the reception level estimated value at the evaluation point is actually corrected. Therefore, effective actual measurement correction according to the positional relationship between the measurement point and the evaluation point is possible.

Here, as described above, the similarity of the propagation environment (propagation loss) varies depending on the surrounding environment (for example, an urban area or a mountain area) even if the distance is the same. Correspondingly, in the second embodiment described above, the path loss error correlation (direct correlation distance d _corr ) as the measurement reliability is determined according to the comprehensive area attribute information. The general area attribute information indicates surrounding environments such as urban areas, suburban areas, and mountainous areas. Therefore, in the case of this embodiment, it is possible to set an appropriate measurement reliability according to the surrounding environment (in this embodiment, a path loss error correlation), and as a result, it is possible to improve the accuracy of actual measurement correction. Become.

  Furthermore, by considering not only the path loss error correlation but also the measurement error variance and the path loss error variance when actually measuring the reception level, the measurement reliability can be reduced while reducing the influence of the measurement error.

  In the second embodiment described above, the case where the comprehensive area attribute information is the area attribute information of the measurement point has been described as an example, but the present invention is not limited to this. For example, a result of comprehensively determining each area attribute information of a plurality of points (for example, measurement points and evaluation points) can be set as “total area attribute information”. Of course, only the area attribute information of the evaluation point or only the area attribute information of the transmission point can be used as the comprehensive area attribute information.

  In the second embodiment described above, the area environment (urban area, suburban area, mountainous area) is used as the area attribute information. However, the area attribute information is not limited to this. Other area attribute information can also be used.

[Third Embodiment]
As the measurement reliability, the path loss error correlation is used in the second embodiment, whereas the path loss error angle correlation described below is used in the third embodiment.

  FIG. 7 is a diagram for explaining the evaluation area 10 in the third embodiment of the present invention, and in particular, for explaining the measurement-evaluation angle θ in the evaluation area 10. In FIG. 7, as in FIG. 3, a transmission station 11 (transmission point 12), an evaluation point 13, and a measurement point 14 exist in the evaluation area 10. In FIG. 7, the measurement-evaluation angle θ is an angle between a line segment connecting the transmission point 12 and the evaluation point 13 and a line segment connecting the transmission point 12 and the measurement point 14.

  Further, the third embodiment is different from the second embodiment only in that the measurement reliability using the measurement-evaluation angle θ as a parameter is used. Therefore, in the radio wave propagation characteristic estimation system according to the third embodiment, a configuration other than the configuration related to the above difference (specifically, the reliability calculation unit 205 and the comprehensive area attribute-specific parameter storage unit 206 shown in FIG. 4). Is the same as the radio wave propagation characteristic estimation system 200 of the second embodiment. Therefore, for the sake of clarity, only the reliability calculation unit 205 and the comprehensive area attribute-specific parameter storage unit 206 will be basically described below.

  The reliability calculation unit 205 calculates the path loss error angle correlation ρ (θ) using the measurement-evaluation angle θ as a parameter as the measurement reliability. This path loss error angle correlation ρ (θ) represents the correlation between the path loss error at the evaluation point 13 and the path loss error at the measurement point 14 that is the measurement-evaluation angle θ. When the measurement-evaluation angle θ is small, the path loss error angle correlation becomes high because the degree of similarity between the surrounding environment of the measurement point 14 and the surrounding environment of the evaluation point 13 is high. When θ is large, it has a property of becoming low.

  FIG. 8 is a table showing an example of the relationship between the comprehensive area attribute information and the function of each path loss error angle correlation in the third embodiment. In the present embodiment, a case where the comprehensive area attribute information is the area attribute information of the measurement point 14 is taken as an example. Further, in the present embodiment, an area environment (three areas, an urban area, a suburb area, and a mountain area) is assumed as the area attribute information. The respective path loss error angle correlation functions are shown as ρ1 (θ), ρ2 (θ), and ρ3 (θ).

  FIG. 9 is a graph of the functions ρ1 (θ), ρ2 (θ), and ρ3 (θ) of each path loss error angle correlation in FIG. 8 (in other words, each characteristic shown in FIG. 9 is functionalized). It can be said that these are functions ρ1 (θ), ρ2 (θ), and ρ3 (θ)). The path loss error angle correlation basically takes a maximum value of 1 when the measurement-evaluation angle θ = 0 °, and decreases as the measurement-evaluation angle θ increases. Note that the path loss error angle correlation in the mountain area (in the case of the function ρ3 (θ)) is measured and evaluated because the path loss error is affected by the undulations of the mountains and topography and the path loss error angle correlation depends on this path loss error. It fluctuates gently with respect to the angle θ. On the other hand, in urban areas (in the case of the function ρ1 (θ)), the path loss error is often caused by buildings, so even if the measurement-evaluation angle θ is the same as the mountain area, the path loss error Angle correlation tends to decrease. The path loss error angle correlation in the suburbs (in the case of the function ρ2 (θ)) roughly shows a change between the two.

  The total area attribute-specific parameter storage unit 206 stores a path loss error angle correlation function corresponding to the above-described total area attribute information. The reliability calculation unit 205 has a path loss error angle correlation function (for example, as shown in FIGS. 8 and 9) according to the comprehensive area attribute information (in the present embodiment, as the area attribute information of the measurement point 14 as an example). , Ρ1 (θ), ρ2 (θ), or ρ3 (θ)) from the general area attribute-specific parameter storage unit 206. The reliability calculation unit 205 calculates the measurement-evaluation angle θ from the position information of the measurement point 14, the position information of the evaluation point 13, and the position information of the transmission point 12, and uses the acquired path loss error angle correlation function, The path loss error angle correlation is calculated. The actual measurement correction unit 207 performs actual measurement correction using the path loss error angle correlation thus calculated as the measurement reliability.

  In the third embodiment described above, the path loss error angle correlation using the measurement-evaluation angle, which is the angle between the line segment connecting the transmission point and the evaluation point, and the line segment connecting the transmission point and the measurement point, as a parameter. The reliability of measurement at the time of actually correcting the estimated reception level at the evaluation point. Therefore, effective actual measurement correction according to the positional relationship between the measurement point and the evaluation point becomes possible.

  In the third embodiment described above, the path loss error angle correlation as the measurement reliability is determined according to the comprehensive area attribute information (for example, the area attribute information of the measurement point). Therefore, it is possible to set an appropriate reliability according to the surrounding environment, and it is possible to improve the accuracy of actual measurement correction.

  In the third embodiment described above, the path loss error angle correlation is used alone for the measurement reliability. However, the path loss error correlation corresponding to the measurement-evaluation distance in the second embodiment is further considered. Is also possible.

  Similarly to the second embodiment, it is possible to consider not only the path loss error angle correlation but also the measurement error variance and the path loss error variance when actually measuring the reception level in the measurement reliability.

[Fourth Embodiment]
The features of the fourth embodiment are different from the second and third embodiments, in addition to the area environment (urban area, suburban area, mountainous area, etc.) as comprehensive area attribute information, and further, the road number (described below) Alternatively, road determination information derived from the road number) is used.

  FIG. 10 is a conceptual diagram of the fourth embodiment of the present invention, and specifically shows an example of the relationship between each measurement point and evaluation point on the road. In FIG. 10, it is determined that the measurement point 20 is on a different road from the evaluation point 13, while the measurement point 21 is on the same road as the evaluation point 13. In the fourth embodiment, whether the measurement point 21 and the evaluation point 13 are on the same road by holding the road number that identifies the road at the position of each point as area attribute information and comparing the road number. Information on whether or not (road determination information) is obtained and used as general area attribute information. Here, “on the same road” means that the angle difference between the measurement point road and the evaluation point road is sufficiently small, that is, it can be regarded as a straight line or a gentle curve. In addition, “on the same road” includes a case where the road of the measurement point and the road of the evaluation point are two parallel roads that are sufficiently close to each other. Conversely, for two roads that do not satisfy the above conditions, the expression “on different roads” will be used.

  As described above, the difference between the present embodiment and the second embodiment is that the area attribute information includes a road number (or road determination information derived from the road number), and the comprehensive area attribute corresponding thereto. The content of the information is different. Therefore, in the radio wave propagation characteristic estimation system according to the fourth embodiment, the configuration other than the configuration related to the above difference (specifically, the reliability calculation unit 205 and the comprehensive area attribute-specific parameter storage unit 206 shown in FIG. 4). Is the same as the radio wave propagation characteristic estimation system 200 of the second embodiment. Therefore, in the following, only the reliability calculation unit 205 and the comprehensive area attribute-specific parameter storage unit 206 will be basically described for the purpose of clarifying the description.

  FIG. 11 is a table showing an example of the correlation distance in the path loss error correlation for each comprehensive area attribute information held in the comprehensive area attribute-specific parameter storage unit 206 in the fourth embodiment. As shown in FIG. 11, as the general area attribute information, the area environment (urban area, suburban area, mountainous area, etc.) and road determination information indicating whether the measurement point and the evaluation point are on the same road are shown. . That is, in FIG. 11, different correlation distances (d1_1, d1_2, d2_1, d2_2, d3_1, d3_2) are assigned to all cases of each comprehensive area attribute information (for every combination of area environment and road determination information). ing. Here, since the propagation environment is similar between two points on the same road compared to two points on different roads, the correlation distance of the path loss error correlation is often long (for example, d1_1> d1_2, d2_1>). d2_2, d3_1> d3_2). In the present embodiment, the area environment in FIG. 11 is a result of comprehensively determining each area environment of a plurality of points (for example, measurement points 21 and evaluation points 13 shown in FIG. 10). Of course, the area environment in FIG. 11 may be an area environment with only the measurement point 21 or an area environment with only the evaluation point 13.

The reliability calculation unit 205 determines whether the measurement point and the evaluation point are on the same road by using, for example, map data (that is, obtains road determination information), and determines the measurement point 21 and the evaluation point 13. Each area environment is comprehensively determined (that is, the area environment is obtained). Here, as a method for obtaining the road determination information, for example, a specific number is assigned to each road on the map data, a road closest to the measurement point 21 or the evaluation point 13 is obtained, and those road numbers are assigned to the respective points. As area attribute information. Next, road determination information can be obtained by comparing the road numbers of the measurement points 21 and the evaluation points 13 and determining whether or not they are “on the same road”. The reliability calculation unit 205 acquires the correlation distance d _corr that matches the obtained total area attribute information from the table data (table data in FIG. 11) held in the total area attribute-specific parameter storage unit 206.

  In the fourth embodiment described above, when the actual correction is performed using the path loss error correlation as the measurement reliability, not only the surrounding area environment but also the measurement point and the evaluation point are on a road different from the case where the evaluation point is on the same road. A correlation distance corresponding to each case is prepared. Therefore, when the measurement point and the evaluation point are on the same road, by increasing the correlation distance, it is possible to calculate a path loss error correlation that matches the actual environment that the propagation environment is similar on the same road. Conversely, when the measurement point and evaluation point are on different roads, the similarity of the propagation environment is reduced compared to the same road by reducing the correlation distance compared to the case on the same road. Thus, it is possible to calculate the path loss error correlation in accordance with That is, in the case of the fourth embodiment, it is possible to use the measurement reliability more suitable for the real environment, so that effective actual measurement correction can be performed.

  In the fourth embodiment, the correlation distance of the path loss error correlation is prepared together with the road determination information (which can be a road number). However, as in the third embodiment, the road determination information (can be a road number) It is also possible to prepare a path loss error angle correlation function.

[Fifth Embodiment]
In the fifth embodiment, unlike the second to fourth embodiments, the reception level estimation value at the evaluation point is measured and corrected using measurement data at a plurality of measurement points.

  FIG. 12 is a diagram for explaining the evaluation area 10 in the fifth embodiment, and specifically shows a state in which a plurality of measurement points exist in the evaluation area 10. As understood from FIG. 12, in the evaluation area 10, in addition to the transmitting station 11 (transmission point 12) and the evaluation point 13, a plurality of measurement points (measurement point # 1 (measurement point 31), measurement point # 2 (Measuring point 32)) is illustrated. In the fifth embodiment, as in the second embodiment, the measurement reliability is calculated according to the path loss error correlation according to the distance between the evaluation point and the measurement point. The actual measurement correction is performed in consideration of the path loss error correlation between the measurement points.

  Based on performing actual measurement correction using a plurality of measurement points, the radio wave propagation characteristic estimation system of this embodiment differs from the radio wave propagation characteristic estimation system 200 of the second embodiment in the following points. The point from which the measurement data determination part 203 which comprises the radio wave propagation characteristic estimation system of this embodiment outputs "a plurality of measurement points" differs from 2nd Embodiment. Furthermore, the point which the propagation estimation part 202 which comprises the radio wave propagation characteristic estimation system of this embodiment estimates a reception level using propagation estimation with respect to "a plurality of measurement points" differs from 2nd Embodiment. However, the operations of the measurement data determination unit 203 and the propagation estimation unit 202 may be performed for a plurality of measurement points, and the basic operations are the same as those in the second embodiment. . Therefore, these descriptions are omitted. On the other hand, the measurement reliability set for a plurality of measurement points and the method of actual measurement correction are different from those of the second embodiment, so that only these points will be basically described below.

First, the reliability calculation unit 204 calculates the measurement reliability of each of a plurality of measurement points with respect to the evaluation point 13. Considering the actual measurement correction when the number of measurement points is K, the measurement reliability w _{k at} each measurement point #k (k is an integer of 1 or more and K or less) is set, and the measurement reliability of all measurement points is w in (Equation 4). Represent as

  As in the second embodiment, the reliability calculation unit 204 calculates the correlation distance of the path loss error correlation corresponding to the area attribute information (for example, the area environment (for example, three areas of the urban area, the suburb area, and the mountain area)). Based on this, a path loss error correlation is calculated. This path loss error correlation is held in the comprehensive area attribute-specific parameter storage unit 206. The measurement reliability of (Equation 4) is determined in consideration of the path loss error correlation between each measurement point in addition to the path loss error correlation between the evaluation point and the measurement point.

  Here, considering the effect of the path loss error correlation between the measurement points on the actual correction, if the path loss error correlation between the measurement points is sufficiently low, the received level measured values at multiple measurement points are independent. Since it fluctuates, a diversity effect can be obtained. Therefore, when the path loss error correlation between the measurement points is low, the accuracy of measurement correction can be improved by setting the measurement reliability that takes a high value to improve the diversity effect.

Such measurement reliability is such that the path loss error correlation between the evaluation point (for convenience, the index is # 0) and the measurement point #k is ρ _{0, k} , and the path loss between the measurement point #k and the measurement point #i. The error correlation can be calculated by the following (Equation 5) with ρ _{k, i} .

In (Expression 5), ρ ₀ is a vector whose elements are path loss error correlations ρ _{0, k} between the evaluation point and the measurement point #k, and is expressed by the following (Expression 6).

In (Expression 5), P is a matrix having a diagonal component of 1 and a non-diagonal component having a path loss error correlation between measurement points as an element, and is expressed by the following Expression (7).

Note that the (k, i) element ρ _{k, i} which is the non-diagonal component of (Expression 7) is the same as the (i, k) element ρ _{i, k} . Further, the path loss error correlations of (Expression 6) and (Expression 7) are calculated based on the correlation distance d _corr corresponding to the comprehensive area attribute acquired from the comprehensive area attribute-specific parameter storage unit 206 and the distance between two points (evaluation point − The distance between the measurement points or the distance between the measurement points and the measurement points) d is calculated by (Expression 1). However, when calculating the path loss error correlation between the measurement points, if the area attribute information of the two measurement points is different, the correlation distance corresponding to the area attribute information at one of the measurement points is used or different. The average value of the correlation distance corresponding to the area attribute information is used.

  The measurement reliability w in (Equation 5) increases the measurement reliability when the path loss error correlation between measurement points is low, and conversely when the path loss error correlation between measurement points is high. Make it smaller. The measurement reliability w calculated in this way is input to the actual measurement correction unit.

Next, in the actual measurement correction unit, K measurement data (reception level actual measurement values at measurement point #k are assumed to be RM _{, k} ) from the measurement data determination unit, and the measurement reliability of each measurement data from the reliability calculation unit (The measurement reliability of measurement point #k is wk), but the propagation estimation unit receives the reception level estimation value at each measurement point calculated using the propagation estimation formula (the reception level estimation value of measurement point #k is E _{M and k} ) and a reception level estimated value (estimated as E _T ) of the evaluation point calculated using the propagation estimation formula. Using these input values, the actual measurement correction unit performs actual measurement correction according to (Equation 8).

In (Equation 8), C _T represents the reception level after the measured corrected.

(Equation 8), path loss error at the measurement point _{#k (R M, k -E M} , k) in which, multiplied by the measurement reliability _{w k} of each measurement point as the weight was corrected reception level estimate _{E T} It is. Reception level C _T after the measured corrected at the evaluation point obtained in this way is output.

  In the fifth embodiment described above, evaluation of each measurement point is performed using a plurality of measurement data and using the path loss error correlation between the evaluation point and each measurement point and the path loss error correlation between each measurement point. The measurement reliability for the point is calculated and the actual measurement is corrected. At this time, not only the measurement reliability is increased when the path loss error correlation between the evaluation point and each measurement point is high, but also the measurement reliability is increased when the path loss error correlation between the measurement points is low. The measurement reliability is determined.

  According to the fifth embodiment, when the path loss error correlation between the measurement points is low, the correlation between the reception level actual measurement values is low, and the diversity effect can be utilized, so that the accuracy of the actual measurement correction can be improved.

  In the fifth embodiment, the path loss error correlation corresponding to the distance between two points is used. However, similarly to the third embodiment, a path loss error angle correlation can also be used.

  Further, the area attribute information used in the fifth embodiment can use not only the area environment but also road determination information (or road number) as in the fourth embodiment.

Furthermore, also in the measurement reliability in the fifth embodiment, the measurement error of the reception level actual measurement value at the measurement point can be taken into consideration as in the second embodiment. The measurement reliability in consideration of the measurement error of the reception level actual measurement value is represented by the following (formula 9) instead of (formula 7), assuming that the variance of the measurement error at the measurement point #k is σ _{M, k} ^2. The measurement reliability of (Equation 5) is calculated using

Here, σ _L ² is the variance of the path loss error in the propagation estimation formula. By using (Equation 9) instead of (Equation 7), the measurement reliability value corresponding to the measurement point with a large measurement error is reduced, and conversely, the measurement reliability corresponding to the measurement point with a small measurement error. Therefore, it is possible to set the measurement reliability according to the measurement error.
[Sixth Embodiment]
In the first to fifth embodiments described above, the system using the actual measurement correction is the radio wave propagation characteristic estimation system. On the other hand, such an actual measurement correction method is also useful in a cognitive radio system that performs communication by sharing the frequency of an existing radio system. In the cognitive radio system, it is necessary to estimate how much interference is caused to the existing radio system so that the interference to the existing radio system due to own transmission does not affect the existing service. The present embodiment describes a cognitive radio system that uses the actual measurement correction method described as the first to fifth embodiments in order to grasp interference.

  FIG. 13 is a configuration diagram of a radio communication system according to the sixth embodiment of this invention. The wireless communication system includes a cognitive wireless system (hereinafter referred to as a secondary system) and an existing wireless system (hereinafter referred to as a primary system). The primary system includes a primary transmitting station 50 having a coverage 52 and a primary receiving station 51. The secondary system includes a secondary transmission station 55 and a monitoring station 56.

  In FIG. 13, the radio wave of the secondary transmission station 55 transmitted in the same frequency band as that of the primary system is an interference with the primary reception station 51. Here, the primary receiving station 51 is located at the area end of the coverage 52 and is the primary receiving station having the highest interference level from the secondary transmitting station 55 among the primary receiving stations in the coverage 52. In the secondary system, by controlling the amount of interference with the primary receiving station 51, control is performed such as setting the interference level below an allowable value so as not to affect the existing service of the primary system.

  The monitoring station 56 is one of secondary system reception stations located around the primary reception station 51 and measures radio waves transmitted from the secondary transmission station 55 and causing interference to the primary reception station 51. By using this measurement data, the level of interference with the primary receiving station 51 is accurately measured and corrected.

  In other words, in the present embodiment, the evaluation point that is the reception level estimation target is the position of the primary reception station 51, the measurement point is the position of the monitoring station 56, and the reception level actual value used for actual measurement correction is the monitoring station 56. The measured interference level.

  FIG. 14 is a block diagram illustrating a configuration example of the secondary system illustrated in FIG. 13. The secondary system includes a secondary transmission station 55, a monitoring station 56, a core network 57, a geographic database 58, and a spectrum manager 59.

  The core network 57 is a network for communicating with the secondary transmission station 55, the monitoring station 56, the geographic database 58, and the spectrum manager 59.

  The geographic database 58 holds information related to the primary system (transmission power, transmission antenna gain, coverage, reception antenna height and reception antenna gain). Information on the primary system held in the geographic database 58 is used by the secondary transmission station 55 and the spectrum manager 59 via the core network 57.

  The spectrum manager 59 controls the interference level from the secondary transmission station 55 and the frequency band to be used so as not to affect the existing service of the primary system. Further, the spectrum manager 59 calculates an interference level from the secondary transmission station 55 to the primary reception station 51 in order to perform the interference level control. First, the spectrum manager 59 acquires information related to the primary system from the geographic database 58, and specifies the position where the interference from the secondary transmission station 55 is maximum (that is, the position of the primary receiving station 51). Next, the spectrum manager 59 calculates a reception level estimation value at the position of the primary reception station 51 using a predetermined propagation estimation formula. Further, the spectrum manager 59 determines the measurement reliability according to the positional relationship of each point and the area attribute information. Then, the spectrum manager 59 uses the measured interference level in the monitoring station 56 and the measurement reliability to actually correct the received level estimation value to calculate the interference level. The interference level calculated here is sent to the secondary transmission station 55. For example, the secondary transmission station 55 performs transmission control such that the interference level is equal to or less than an allowable value. Thereby, it is possible to prevent the service of the secondary system from affecting the existing service of the primary system.

  FIG. 15 is a flowchart for explaining an operation example of the spectrum manager 59 shown in FIG. 14 (mainly an operation example related to the interference level calculation).

  First, the spectrum manager 59 specifies the position (that is, “evaluation point”) of the primary receiving station 51 where the level of interference is maximum within the coverage 52 (step S20).

  Next, in order to obtain measurement data used for actual measurement correction, the spectrum manager 59 is a monitoring station 56 (a receiving station of a secondary system located around the primary receiving station 51, and the position is referred to as a “measurement point”. In response, the monitoring instruction for measuring the radio wave transmitted from the secondary transmission station 55 is transmitted (step S21). Here, the measurement data includes an actually measured interference level (monitoring result in the monitoring station 56), measurement point information (position of the monitoring station 56, measurement antenna height, measurement antenna gain, etc.), and area attributes of the measurement point. Associated information.

  Subsequently, the spectrum manager 59 receives measurement data from the monitoring station 56 after the monitoring station 56 measures the interference level (step S22).

  The spectrum manager 59 calculates a propagation loss from the secondary transmission station 55 to the primary reception station 51 using a predetermined propagation estimation formula. Then, the spectrum manager 59 uses the propagation loss, the transmission power and transmission antenna gain of the secondary transmission station 55, and the reception antenna gain of the primary reception station 51 to estimate the interference level to the primary reception station 51 ( That is, the “evaluation point reception level estimated value” in the first to fifth embodiments is calculated (step S23).

  Then, the spectrum manager 59 calculates the measurement reliability based on the positional relationship and the area attribute information of the primary reception station 51, the secondary transmission station 55, and the monitoring station 56, and determines the measured interference level according to the measurement reliability. Actual measurement correction of the used interference level estimation value is performed (step S24).

  That is, the spectrum manager 59 has a function related to the actual measurement correction of the radio wave propagation characteristic estimation system in the first to fifth embodiments, and corrects the estimated value of the interference level to the primary receiving station 51 using the actual measurement correction.

  According to the sixth embodiment described above, in a cognitive radio system that performs communication by sharing a frequency band with an existing radio system, the interference control can be performed with high accuracy without depending on the positional relationship of each point and the surrounding environment. It can be carried out. This is because the interference level that is the basis of the interference control is the positional relationship between the measurement point (position of the monitoring station 56), the evaluation point (position of the primary reception station 51), and the transmission point (secondary transmission station 55) and the area attribute. This is because it is calculated by actual measurement correction in consideration of measurement reliability according to information.

  The area attribute information described above can be a result of comprehensive determination of area attribute information of at least two or more points, or area attribute information of any point.

  Further, in the sixth embodiment described above, in the spectrum manager 59, the interference level estimation using the propagation estimation formula and the actual measurement correction using the actual measurement value of the interference level are performed. It is also possible to use this apparatus. For example, the secondary transmission station may perform the interference level estimation and the actual measurement correction.

  In the sixth embodiment described above, the actual correction using the actual measurement value of the interference level is the target. However, the monitoring station 56 transmits the signal transmitted from the primary transmission station 50 and received by the primary reception station 51 ( In the following, it is also possible to measure the radio wave of the primary signal. In this case, the spectrum manager 59 estimates the reception level of the primary signal received by the primary reception station 51 using the propagation estimation formula, and uses the actual measurement value of the primary signal obtained by the measurement of the monitoring station 56. By correcting, it is possible to accurately estimate the coverage 52 of the primary system. Further, the spectrum manager 59 calculates the carrier-to-interference power ratio in the primary receiving station 51 by performing both the actual correction regarding the interference level and the actual correction regarding the primary signal, and uses it for controlling the interference level. Also good.

  In the sixth embodiment described above, the second to fifth embodiments can be applied.

  To summarize the above, when the first to sixth embodiments described above are used, when the estimated value of the reception level at the evaluation point is actually corrected, the effectiveness of the measurement data used for the actual correction is expressed as the measurement point and the evaluation point. Since the measurement reliability is determined according to the positional relationship with the transmission point, the accuracy of the actual measurement correction can be increased.

  In addition, in the first to sixth embodiments, the measurement reliability depends on area attribute information (a result of comprehensively determining area attribute information of at least two or more points, or area attribute information of each point). Therefore, it is possible to set an appropriate reliability according to the surrounding environment, and it is possible to perform actual measurement correction without deteriorating accuracy.

  The first to sixth embodiments described above can also be embodied as predetermined hardware, for example, a circuit.

Further, the first to sixth embodiments described above can be controlled and operated by a computer circuit (for example, a CPU (Central Processing Unit)) (not shown) based on a control program. In this case, these control programs are stored in, for example, a storage medium (for example, ROM (Read Onl) in the apparatus or the system.
y Memory), a hard disk, etc.) or an external storage medium (for example, a removable medium, a removable disk, etc.), and read and executed by the computer circuit.

DESCRIPTION OF SYMBOLS 10 Evaluation area 11 Transmission station 12 Transmission point 13 Evaluation point 14, 20, 21, 31, 32 Measurement point 50 Primary transmission station 51 Primary reception station 52 Coverage 55 Secondary transmission station 56 Monitoring station 57 Core network 58 Geographic database 59 Spectrum manager 100 , 200 Radio wave propagation characteristic estimation system 101 Propagation estimation unit 102 Total area attribute-specific reliability calculation unit 103 Actual measurement correction unit 202 Propagation estimation unit 203 Measurement data determination unit 204 Measurement data storage unit 205 Reliability calculation unit 206 Parameter storage by total area attribute Section 207 Actual correction section

Claims (17)

Of radio waves emitted from the transmitting point to a transmitting station, a receiving level estimation value is an estimated value of the reception level definitive any evaluation point in the evaluation area that estimates the radio wave propagation characteristics, the reception level measured measured at the measuring point A system for correcting actual measurements using values,
A propagation estimating section for calculating a pre Ki受 signal level estimate using a predetermined propagation estimation formula,
Based on the reliability indicating the relationship between the propagation loss at the evaluation point and the propagation loss at the measurement point of the radio wave transmitted from the transmission point, an actual measurement correction unit that actually corrects the reception level estimation value;
A reliability function that outputs a measurement reliability by inputting a positional relationship between the evaluation point, the transmission point, and the measurement point, for each comprehensive area attribute information comprehensively determined based on the positional relationship and the area attribute information A radio wave propagation characteristic estimation system comprising: an area attribute-specific reliability calculation unit that obtains the reliability by inputting the positional relationship to the selected reliability function .   2. The radio wave propagation characteristic estimation system according to claim 1, wherein the area attribute information is an area environment around at least one of the evaluation point, the transmission point, and the measurement point.   The area attribute information is a road number where the measurement point and the evaluation point are located, and the reliability is calculated according to whether or not the measurement point and the evaluation point are located on the same road. The radio wave propagation characteristic estimation system according to claim 1 or 2, characterized in that   The radio wave propagation characteristic estimation system according to claim 1, wherein the positional relationship is a distance between the evaluation point and the measurement point.   5. The position relationship is an angle formed by a line segment connecting the transmission point and the evaluation point and a line segment connecting the transmission point and the measurement point. 6. The radio wave propagation characteristic estimation system described in 1.   The radio wave propagation characteristic according to any one of claims 1 to 5, wherein the reliability uses a path loss error correlation that is a correlation between a path loss error at the evaluation point and a path loss error at the measurement point. Estimation system.   7. The radio wave propagation characteristic estimation system according to claim 6, wherein the reliability is determined by using a measurement error variance and a path loss error variance when actually measuring a reception level in addition to the path loss error correlation. .   The radio wave propagation characteristic estimation system according to claim 6 or 7, wherein the reliability is further determined according to a path loss error correlation between a path loss error at the measurement point and a path loss error at another measurement point.   The propagation estimation unit calculates a reception level estimation value of the measurement point, and the actual measurement correction unit corrects a value obtained by multiplying the difference between the reception level estimation value and the reception level actual measurement value by the reliability. The radio wave propagation characteristic estimation system according to any one of claims 1 to 8, wherein a reception level estimation value of the evaluation point is corrected as a value. Of the radio wave transmitted from the transmission point of the transmitting station, a receiving level estimation value is an estimated value of the reception level definitive any evaluation point in the evaluation area that estimates the radio wave propagation characteristics, the reception level measured measured at the measuring point A system for correcting actual measurements using values,
A propagation estimating section for calculating a pre Ki受 signal level estimate using a predetermined propagation estimation formula,
Based on the reliability indicating the relationship between the propagation loss at the evaluation point and the propagation loss at the measurement point of the radio wave transmitted from the transmission point, an actual measurement correction unit that actually corrects the reception level estimation value;
A comprehensive area in which the correlation distance between the propagation loss error at the evaluation point and the propagation loss error at the measurement point is comprehensively determined based on the positional relationship between the evaluation point, the transmission point, and the measurement point, and area attribute information A reliability calculation unit configured to calculate the reliability based on a propagation loss error correlation determined by the selected correlation distance and a distance between the evaluation point and the measurement point, which is defined for each attribute information ;
A radio wave propagation characteristic estimation system comprising:   A path loss error correlation that is a correlation between a path loss error at the evaluation point and a path loss error at the measurement point is calculated using the distance between the evaluation point and the measurement point and the correlation distance, and the calculation result is The radio wave propagation characteristic estimation system according to claim 10, wherein the radio wave propagation characteristic estimation system is used for reliability.   12. The radio wave propagation characteristic estimation system according to claim 11, wherein the reliability is determined by using a measurement error variance and a path loss error variance at the time of actual reception level measurement in addition to the path loss error correlation. .   The radio wave propagation characteristic estimation system is a system that performs actual measurement correction using actual reception level values measured at a plurality of measurement points, and the reliability includes path loss errors at the evaluation points and path loss errors at the measurement points. The radio wave propagation characteristic estimation system according to claim 11, wherein the radio wave propagation characteristic estimation system is determined in accordance with a path loss error correlation.   The radio wave propagation characteristic estimation system is a system that performs actual measurement correction using actual reception level values measured at a plurality of measurement points, and the reliability further includes a path loss error at a measurement point different from the path loss error at the measurement point. The radio wave propagation characteristic estimation system according to any one of claims 11 to 13, wherein the radio wave propagation characteristic estimation system is determined according to a path loss error correlation with an error.   The propagation estimation unit calculates a reception level estimation value of the measurement point, and the actual measurement correction unit corrects a value obtained by multiplying the difference between the reception level estimation value and the reception level actual measurement value by the reliability. The radio wave propagation characteristic estimation system according to any one of claims 10 to 14, wherein a reception level estimation value of the evaluation point is corrected as a value. Of radio waves emitted from the transmitting point to a transmitting station, a receiving level estimation value is an estimated value of the reception level definitive any evaluation point in the evaluation area that estimates the radio wave propagation characteristics, the reception level measured measured at the measuring point A method for correcting actual measurement using a value,
Calculating a pre Ki受 signal level estimate using a predetermined propagation estimation formula,
Based on the reliability indicating the relationship between the propagation loss at the evaluation point and the propagation loss at the measurement point of the radio wave transmitted from the transmission point, the reception level estimation value is actually corrected,
Overall area attribute information reliability function, which comprehensively determined based on the positional relationship and the area attribute information outputs the measurement reliability by inputting the positional relationship between the measurement points before and Symbol evaluation point and the transmission point A radio wave propagation characteristic estimation method, wherein the reliability is obtained by inputting the positional relationship into the reliability function defined and selected for each . Of radio waves emitted from the transmitting point to a transmitting station, a receiving level estimation value is an estimated value of the reception level definitive any evaluation point in the evaluation area that estimates the radio wave propagation characteristics, the reception level measured measured at the measuring point A computer program for correcting actual measurement using values,
A process of calculating the Ki受 signal level estimate before using a predetermined propagation estimation formula,
Based on the reliability indicating the relationship between the propagation loss at the evaluation point and the propagation loss at the measurement point of the radio wave transmitted from the transmission point, the process of actually correcting the reception level estimate,
Overall area attribute information reliability function, which comprehensively determined based on the positional relationship and the area attribute information outputs the measurement reliability by inputting the positional relationship between the measurement points before and Symbol evaluation point and the transmission point Processing for obtaining the reliability by inputting the positional relationship to the reliability function defined and selected for each ;
Is executed by a computer.

Images