JP6455818B2 - Attenuation coefficient estimation device, attenuation coefficient estimation method, and program - Google Patents

Description

  The present invention relates to an attenuation coefficient estimation device and the like for estimating an attenuation coefficient of an attenuation characteristic function related to attenuation characteristics of radio waves from a wave source.

  In recent years, effective use of frequency bands (white space) that are not used spatially and temporally as one of the means to improve frequency utilization efficiency to cope with the tightness of frequency resources and the explosive increase in mobile traffic. Is mentioned. As described above, in order to efficiently use the vacant frequency band, it is necessary to appropriately grasp the spatial and temporal vacancy conditions for each frequency.

  As such a white space detection method, for example, there is a method using a spectrum sensing technique. In this method, the white space region can be detected by determining the presence or absence of a spectrum at the position where the sensor (receiving device) is arranged.

  However, in the method using the spectrum sensing technique, the sensor arrangement granularity and the spatial accuracy of the white space that can be detected are in a trade-off relationship. Therefore, in order to detect the white space with high spatial accuracy, it is necessary to increase the arrangement granularity of the sensor, and there is a problem that the detection cost increases.

  As a method that can solve such problems and estimate propagation loss with high accuracy even with a small number of reception points, when determining the attenuation characteristic function in a certain azimuth direction around the wave source, The estimation is performed so that the influence becomes smaller as the reception points in the farther direction are received (see, for example, Non-Patent Document 1).

Kenji Horibata, Kazuo Kanno, Goro Hasegawa, Toshiyuki Maeyama, Yoshio Takeuchi, "Propagation Loss Estimation Method Using Azimuth Variable by Weighted Least Squares Method", Proceedings of Society Conference of IEICE, p. 403, September 2014

The method described in Non-Patent Document 1 uses a weight function that decreases as the distance from the azimuth direction increases in order to reduce the influence of the reception point in the direction away from the azimuth direction. The function usually has one or more parameters indicating the degree of reduction. For example, the function may be as follows: Note that θ is a certain azimuth, and θ _i is the azimuth of the reception point. In the case of the following expression, α and β are parameters.

  In the method described in Non-Patent Document 1, when the parameters α and β are changed, the attenuation characteristic functions estimated in accordance with the parameters α and β are changed, and as a result, the detected white space is different. Specifically, as shown in FIG. 9, it is apparent that the shape of the white space is different between α = 0.7 and β = 1 and α = 0.9 and β = 1. It is. Therefore, it is required to set an appropriate parameter value in the function of the weight.

  The present invention has been made in order to solve the above-described problem, and an attenuation coefficient estimation that can estimate an appropriate attenuation coefficient of an attenuation characteristic function by using a weight function in which an appropriate parameter value is set. An object is to provide a device or the like.

In order to achieve the above object, an attenuation coefficient estimation apparatus according to the present invention is a set of a plurality of observation information having a received signal intensity of a radio wave received from a wave source by a receiving apparatus, and a distance and an azimuth angle from the wave source to the receiving apparatus. A reception unit that accepts a certain observation set, and a function related to the attenuation characteristic of the radio wave from the wave source with respect to a specific azimuth, and an attenuation coefficient that is a coefficient of the attenuation characteristic function that is a function depending on the distance from the wave source. Azimuth away from a specific azimuth by using a plurality of observation information included in and a weight function that is a function of weight that decreases as the distance from the specific azimuth increases, and that includes one or more parameters related to the decrease The value of the parameter can be estimated by performing the regression analysis, which has a smaller effect on the observation information including the angle, for multiple azimuths and multiple values of the parameter. , An estimation unit that obtains correspondence information that associates attenuation coefficients for each of a plurality of azimuth angles estimated using a parameter value weight function, a plurality of parameter values, a parameter value, and a parameter value weight function , And a plurality of azimuth characteristics, which are characteristics of the azimuth direction of the attenuation coefficient for each azimuth angle, estimated using a high-density observation set that is a set of observation information larger than the observation set. Using the reference correspondence information and the reference information storage unit that stores a plurality of pieces of reference information including correct values that are the values of parameters suitable for the high-density observation set, and the plurality of pieces of correspondence information acquired by the estimation unit, Acquire the azimuth characteristics of the attenuation coefficient for each value, and set the azimuth characteristics for each acquired parameter value to the values of the parameters related to multiple reference correspondence information included in the reference information. A similarity determination unit that determines whether or not the azimuth characteristics are similar, and a reference having a plurality of reference correspondence information determined by the similarity determination unit to be similar to the azimuth characteristics for each parameter value corresponding to the plurality of correspondence information A specifying unit that specifies an attenuation coefficient associated with the correct value of the parameter included in the information by the correspondence information.
When the azimuth characteristics of the attenuation coefficient for each parameter value are similar, it is considered that the appropriate value of the parameter in the weight function is also similar. The attenuation coefficient using the set weight function can be estimated. As a result, for example, the white space calculated using the attenuation characteristic function having the attenuation coefficient is appropriate.

In addition, in the attenuation coefficient estimation device according to the present invention, when there is no plurality of reference correspondence information determined by the similarity determination unit to be similar to the azimuth characteristic for each parameter value corresponding to the plurality of correspondence information, A request information output unit that outputs request information for requesting reference information about the reference information, and a reference information reception unit that receives reference information about the radio wave from the wave source according to the output of the request information by the request information output unit, and stores it in the reference information storage unit The specifying unit may specify the attenuation coefficient associated with the correct value of the parameter included in the reference information received by the reference information receiving unit by the correspondence information.
With this configuration, when appropriate reference information corresponding to a certain wave source is not stored, the reference information corresponding to the wave source can be received, and by using the correct value of the parameter included in the reference information An appropriate attenuation coefficient for the wave source can be estimated. In addition, in this way, by increasing the number of reference information stored in the reference information storage unit, it is possible to estimate the attenuation coefficient corresponding to the observation set received by the receiving unit without receiving the reference information Sexuality can be increased. On the other hand, when appropriate reference information corresponding to a certain wave source is stored, an appropriate attenuation coefficient can be estimated without newly acquiring reference information. As a result, the attenuation coefficient can be estimated using less observation information, and the number of observation information measurements can be reduced.

Further, in the attenuation coefficient estimation apparatus according to the present invention, a high-density observation set receiving unit that receives a high-density observation set related to radio waves from a wave source, a weight function, and a high-density observation according to the output of request information from the request information output unit Using the high-density observation set received by the set reception unit, information associating the parameter value with the attenuation coefficient for each of a plurality of azimuth angles estimated using the weight function of the parameter value A reference estimation unit that acquires a plurality of reference correspondence information by acquiring the azimuth characteristics of attenuation coefficients for each of a plurality of azimuth angles, a parameter value acquired by the reference estimation unit, and a plurality of values From the multiple pieces of information that correspond to the attenuation coefficient for each azimuth angle, the multiple azimuth angles that fit the high-density observation set received by the high-density observation set acceptance unit And a correct value specifying unit that specifies a correct value that is a parameter value corresponding to the specified attenuation characteristic, and the reference information receiving unit includes the reference correspondence information acquired by the reference estimating unit And reference information including the correct value specified by the correct value specifying unit may be received.
With such a configuration, the reference information can be acquired using the received high-density observation set.

Further, in the attenuation coefficient estimation apparatus according to the present invention, the range estimation unit that estimates the range in which the radio wave from the wave source reaches and the range estimation unit use the attenuation characteristic function including the attenuation coefficient specified by the specifying unit. And an output unit that performs output related to the range.
With such a configuration, for example, the reach of radio waves can be estimated.

  According to the attenuation coefficient estimation apparatus and the like according to the present invention, it is possible to estimate an attenuation coefficient using a weight function in which appropriate parameter values are set. As a result, for example, the white space calculated using the attenuation characteristic function having the attenuation coefficient is appropriate.

The figure which shows the structure of the information communication system containing the attenuation coefficient estimation apparatus by embodiment of this invention The block diagram which shows the structure of the attenuation coefficient estimation apparatus by the embodiment The flowchart which shows the operation | movement of the attenuation coefficient estimation apparatus by the embodiment The flowchart which shows the operation | movement of the attenuation coefficient estimation apparatus by the embodiment The flowchart which shows the operation | movement of the attenuation coefficient estimation apparatus by the embodiment The flowchart which shows the operation | movement of the attenuation coefficient estimation apparatus by the embodiment The flowchart which shows the operation | movement of the attenuation coefficient estimation apparatus by the embodiment The figure for demonstrating acquisition of the observation set in the embodiment The figure for demonstrating acquisition of the high-density observation set in the embodiment The figure which shows an example of the reachable range and white space in the embodiment The figure which shows an example of the reachable range and white space in the embodiment Schematic diagram showing an example of the appearance of the computer system in the embodiment The figure which shows an example of a structure of the computer system in the embodiment Diagram for explaining the relationship between the parameter value of the weight function and the estimated power

  Hereinafter, an attenuation coefficient estimation apparatus according to the present invention will be described using embodiments. In the following embodiments, components and steps denoted by the same reference numerals are the same or equivalent, and repetitive description may be omitted. The attenuation coefficient estimation apparatus according to the embodiment of the present invention specifies an appropriate parameter value corresponding to a certain observation set by using the similarity of the azimuth angle characteristic regarding the attenuation coefficient of the attenuation characteristic function, and sets the parameter value as the parameter value. The range in which the radio wave from the wave source reaches is estimated using the corresponding attenuation coefficient.

  FIG. 1 is a diagram showing a configuration of an information communication system including an attenuation coefficient estimation device 3 according to the present embodiment. In FIG. 1, the information communication system according to the present embodiment includes a plurality of receiving apparatuses 1 and an attenuation coefficient estimating apparatus 3. The plurality of receiving apparatuses 1 and the attenuation coefficient estimating apparatus 3 are connected via a wired or wireless communication line 100. The communication line 100 may be, for example, the Internet, an intranet, a public telephone line network, or the like. As will be described later, the plurality of receiving devices 1 and the attenuation coefficient estimating device 3 may not be connected via the communication line 100.

  The receiving device 1 receives radio waves from the wave source 2. The receiving device 1 usually acquires the received signal from the wave source 2 in response to the reception of the radio wave, but this need not be the case. The received signal may be, for example, IQ data of a baseband signal, a complex amplitude value, or the like. When the reception signal is not acquired, the reception device 1 may acquire the reception power of the radio wave from the wave source 2. Moreover, when the position of the receiving device 1 is unknown, the receiving device 1 may perform a process of acquiring the position. When the receiving device 1 is movable, it is preferable to perform a process for acquiring the position of the receiving device 1. The number and arrangement location of the receiving apparatuses 1 are not limited, but it is preferable that a sufficient number of receiving apparatuses 1 for estimating the attenuation characteristic function exist as uniformly as possible around the wave source 2. Further, FIG. 1 shows a case where a plurality of receiving apparatuses 1 exist, but this need not be the case. One movable receiving device 1 may receive radio waves from the wave source 2 at a plurality of points. 1 shows a case where the receiving antenna of the receiving device 1 is a parabolic antenna, it goes without saying that this need not be the case.

  When the position of the own apparatus is acquired by the receiving apparatus 1, the position may be acquired using, for example, a GPS (Global Positioning System) or an autonomous navigation apparatus such as a gyro. Alternatively, it may be performed using a nearest base station such as a mobile phone or a wireless LAN, or may be performed by other methods.

In addition, the receiving device 1 may calculate a received signal strength, which will be described later, using the acquired received signal and received power. The receiving device 1 may acquire the distance and azimuth angle from the wave source 2 to its own device. The distance and azimuth will be described later. The receiving apparatus 1 may calculate the distance or the like using, for example, the position of the wave source 2 and the position of the own apparatus. The receiving device 1 may transmit the received power or the received signal strength to the attenuation coefficient estimating device 3. As will be described later, in the attenuation coefficient estimation device 3, when the height of the reception antenna from which the reception device 1 has received radio waves or a reception device identifier that identifies the reception device 1 is necessary, the reception device 1 Such information may be transmitted to the attenuation coefficient estimation device 3 directly or via another server. In that case, for example, the height of the receiving antenna may be included in the observation information described later and transmitted. Note that the position of the wave source 2 may be known, for example, or may be calculated using a method such as TDoA (Time Difference of Arrival) or DoA (Direction of Arrival). Here, for details of the calculation method of the position by TDoA or DoA, refer to the following document, for example.
Literature: K. Ho, Y. Chan, “Solution and performance analysis of geolocation by tdoa”, IEEE Transactions on Aerospace and Electronic Systems, vol. 29, no. 4, p. 1311-1322, October 1993 Literature: SU Pillai, "Array Signal Processing", Springer-Verlag, 1989

  The wave source 2 may be anything as long as it transmits radio waves. For example, the wave source 2 may be a radio base station such as a mobile phone or a base station of a radio system such as a taxi. Other radio waves may be transmitted. Further, the number of wave sources 2 may be one, or two or more. When two or more wave sources 2 exist, these wave sources 2 may exist at substantially the same position and transmit radio waves having different frequencies, for example. In this case, the wave sources 2 may transmit radio waves via the transmission antenna having the same gain with the same transmission power. The wave source 2 may transmit only radio waves having a single frequency, or may transmit two or more radio waves having different frequencies. In addition, FIG. 1 shows a case where a plurality of receiving apparatuses 1 exist around the wave source 2, but the positions of the wave sources 2 may not be known in advance, and thus the plurality of receiving apparatuses 1 are connected to the wave source 2. It is preferred that they are arranged throughout the possible range.

  FIG. 2 is a block diagram showing a configuration of the attenuation coefficient estimation apparatus 3 according to the present embodiment. The attenuation coefficient estimation apparatus 3 according to the present embodiment includes a reception unit 11, an estimation unit 12, a storage unit 13, a reference information storage unit 14, a similarity determination unit 15, a specification unit 16, and a range estimation unit 17. , An output unit 18, a request information output unit 19, a high-density observation set reception unit 20, a reference estimation unit 21, a correct answer value specification unit 22, and a reference information reception unit 23. Note that the attenuation coefficient estimation device 3 may have other components. For example, when transmitting information to the receiving device 1, the attenuation coefficient estimating device 3 may include a transmitting unit that transmits information.

The reception unit 11 receives an observation set. An observation set is a set of a plurality of observation information. That is, the observation set includes a plurality of observation information. The observation set may be stored in a recording medium (not shown). The observation information is information having the received signal intensity of the radio wave received by the receiving device 1 from the wave source 2 and the distance and azimuth angle from the wave source 2 to the receiving device 1. That is,
Observation information = (distance, azimuth, received signal strength)
It may be.

Here, the received signal strength is the strength (spatial power value) of radio waves immediately before passing through the receiving antenna of the receiving device 1. Therefore, the received signal strength does not include the influence of the gain of the receiving antenna, and is expressed by the following equation. In the following equation, the reception power is the power of the signal received by the reception device 1 via the reception antenna.
Received signal strength = Received power-Receive antenna gain

  The distance from the wave source 2 to the receiving device 1 is usually a linear distance between the wave source 2 and the receiving device 1. Further, the azimuth angle from the wave source 2 to the receiving device 1 is an angle indicating the direction from the wave source 2 to the receiving device 1. The azimuth angle may be, for example, with the wave source 2 as the center, north at 0 degrees, east at 90 degrees, and other directions as a reference.

The observation information may also include the frequency (sensing frequency) of the radio wave received by the receiving device 1 from the wave source 2. That is,
Observation information = (distance, azimuth, received signal strength, frequency)
It may be. When the frequency is also used in the estimation of the attenuation characteristic function to be described later, it is necessary for the observation information to include the frequency of the radio wave. Note that the fact that the observation information has a frequency may be the same situation as when the observation information substantially has a frequency. That is, even when (distance, azimuth angle, received signal strength) is managed for each frequency, it may be considered that the observation information includes the frequency.

  Note that the plurality of pieces of observation information included in one observation set may be created using received power acquired by the plurality of receiving apparatuses 1 or one or more movable items. It may be created using received power or the like acquired by the receiving device 1. In addition, it is assumed that a plurality of pieces of observation information included in one observation set are usually a plurality of pieces of observation information related to radio waves transmitted from one wave source 2. In this embodiment, this case will be mainly described. The plurality of pieces of observation information included in one observation set may be a plurality of pieces of observation information relating to radio waves from a plurality of wave sources 2 that are present at substantially the same position and transmit radio waves having different frequencies.

  Further, the received signal strength included in the observation information may be larger than a predetermined threshold. That is, observation information may be generated only for radio waves having a received signal strength greater than such a threshold. The threshold may be as large as background noise, for example. This is to avoid using useless information when estimating the attenuation characteristic function.

  For example, the reception unit 11 may receive an observation set transmitted via a wired or wireless communication line, may receive an observation set from a component that generates observation information, and may receive a predetermined recording medium (for example, Observation sets read from optical disks, magnetic disks, semiconductor memories, etc. may be received. Specifically, the reception unit 11 may receive an observation set including a plurality of observation information transmitted from one or more receiving devices 1. In addition, when information such as received power transmitted from the receiving device 1 is received by another device, and observation information is generated based on the received information in the device, the reception unit 11 May receive an observation set including a plurality of observation information. In addition, when the information transmitted from the reception device 1 is received by the attenuation coefficient estimation device 3 and the observation information is generated from the received information by other components other than the reception unit 11, the reception unit 11 An observation set including a plurality of observation information may be received from the constituent elements. In addition, the reception unit 11 may receive a plurality of pieces of observation information included in one observation set at a time or may be received separately. In the latter case, the observation set may be accepted as a result by sequentially accepting a plurality of pieces of observation information. The same applies to a case where a high-density observation set receiving unit 20 described later receives a high-density observation set. Note that the process of generating the observation information from the information received from the receiving device 1 may include, for example, a process of calculating the received signal strength from the received power. From the position of the receiving device 1 and the wave source 2, Processing for calculating the distance and direction from the wave source 2 to the receiving device 1 may be included. If the reception unit 11 does not receive the observation set via the communication line 100, the attenuation coefficient estimation device 3 may not be connected to the communication line 100. In addition, the reception unit 11 may or may not include a device (for example, a modem or a network card) for reception. The receiving unit 11 may be realized by hardware, or may be realized by software such as a driver that drives a predetermined device.

  The estimation unit 12 estimates an attenuation coefficient, which is a coefficient of an attenuation characteristic function related to a specific azimuth angle with the wave source 2 as the center, using a plurality of observation information included in the observation set received by the reception unit 11. The attenuation characteristic function is a function related to the attenuation characteristic of the radio wave from the wave source 2 and is a function depending on the distance from the wave source 2. The attenuation characteristic function may indicate, for example, radio wave propagation loss (path loss) or the like, or may indicate received signal strength or the like. As will be described later, since the sum of the path loss and the received signal strength is usually a constant transmission power, they are values that are related to each other. Estimating the attenuation characteristic function means specifying an attenuation coefficient included in the attenuation characteristic function. Therefore, it may be considered that estimating the attenuation coefficient means estimating an attenuation characteristic function. The estimation unit 12 estimates the attenuation characteristic function for a plurality of directions (azimuth angles) from the wave source 2 by repeatedly estimating the attenuation characteristic function for different specific azimuth angles. The plurality of directions may be, for example, all azimuth angles (360 degrees) at predetermined angle intervals (for example, 5 degrees and 10 degrees), or a certain azimuth angle at each angle interval. It may be a range (for example, from 90 degrees to 270 degrees). Note that the angular intervals may not be uniform. In the present embodiment, a case will be mainly described in which the estimation unit 12 estimates the attenuation coefficient for all azimuth angles at predetermined angle intervals. In addition, when estimating the attenuation characteristic function of a specific azimuth angle from the wave source 2, the estimation unit 12 also estimates the attenuation characteristic function using observation information other than the specific azimuth angle. At this time, the estimation unit 12 performs the estimation by regression analysis in which observation information including an azimuth angle far from a specific azimuth has a smaller influence, and observation information including an azimuth close to a specific azimuth has a larger influence. Shall be performed. The estimation of the attenuation characteristic function by the regression analysis may be performed using, for example, the least square method, or may be performed using the minimum absolute value method. That is, the estimation unit 12 may calculate the attenuation characteristic function by a weighted least square method or a minimum absolute value method using a weight that decreases as the distance from a specific azimuth angle increases. In that case, the attenuation characteristic function fitting to the observation information is specified in consideration of the weight. Therefore, the estimation unit 12 estimates the attenuation coefficient related to a specific azimuth using a weight function that is a function of a weight that decreases as the distance from the specific azimuth increases and includes one or more parameters related to the decrease. It will be. The number of parameters included in the weight function may be one, or may be two or more. The weight function is, for example, a function that becomes larger as the absolute value of the difference between the azimuth angle included in the observation information and the specific azimuth is smaller, and smaller as the absolute value of the difference is larger. Good. A specific example of the function will be described later. For example, the maximum value of the weight may be 1, the minimum value may be 0, or another value. Moreover, the estimation part 12 may perform a regression analysis using the observation information which has a different frequency. In that case, the attenuation characteristic function is a function that also depends on the frequency of the radio wave. Further, the regression analysis performed by the estimation unit 12 may be a linear regression analysis such as a least square method or a minimum absolute value method, or may be a nonlinear regression analysis. In the latter case, the attenuation characteristic function may be estimated by improving the approximate solution by iterative calculation, for example, by an iterative least square estimation method.

Here, the relationship between the received signal strength and the transmission power is
Received signal strength = transmission power−path loss. As described above, the attenuation characteristic function estimated by the estimation unit 12 may indicate “path loss” in the above equation, or may indicate “transmission power−path loss” (= received signal strength). Good. This is because both can be considered to be related at least to the attenuation characteristics of radio waves. In the present embodiment, a case where the attenuation characteristic function indicates “transmission power−path loss”, that is, a case where the attenuation characteristic function is a function indicating the received signal strength according to the distance from the wave source 2 will be mainly described. Note that the “transmission power” in the above equation is strictly the antenna power including the influence of the gain of the transmission antenna. Here, the transmission power is normally considered not to change. Next, the estimation of the attenuation characteristic function will be described separately for the case where the frequency is not used and the case where the frequency is used.

[Estimation of attenuation characteristic function without using frequency]
In this case, the observation set received by the receiving unit 11 is as follows. In the i-th observation information (x _i , θ _i , P _i ), x _i is a distance (km) from the wave source 2 to the receiving device 1, and θ _i is a receiving device centered on the wave source 2. 1 is an azimuth angle (deg) of 1, and P _i is a received signal intensity (dBm) of a radio wave received by the receiving device 1 at positions x _i and θ _i . The receiving device 1 is a receiving device 1 that has received a radio wave corresponding to the i-th observation information. N is an integer of 2 or more, and is the total number of observation information.
Observation set = {(x ₁ , θ ₁ , P ₁ ), (x ₂ , θ ₂ , P ₂ ),..., (X _N , θ _N , P _N )}

Next, a specific azimuth angle corresponding to a specific direction is defined as θ. Then, the attenuation characteristic function P _θ (dBm) of the specific azimuth angle θ is defined as follows: Note that x _theta, which is the center of the direction of a particular azimuth angle theta distance from (wave source 2) (miles). Further, it is assumed that the attenuation characteristic function indicates the received signal strength.
P _θ = g _θ (x _θ , θ)
Here, for the received signal strength P _i of the i-th observation information (x _i , θ _i , P _i ), the residual from P _θ is δ _i .
δ _i = P _i −g _θ (x _i , θ)

Then, the estimation unit 12 calculates g _θ that is an optimal solution for optimizing the next objective function E _θ for all observation information. Note that the optimization is to minimize the objective function. The calculation of g _θ that minimizes the objective function may be performed using, for example, the steepest descent method or the like, or may be performed using other methods. Incidentally, F (θ _i) becomes smaller as the theta _i leaves the particular azimuth angle theta, a larger weight as theta _i approaches the particular orientation angle theta. N is the total number of observation information as described above.

Next, g _θ (x _θ , θ) will be described. For example, g _θ (x _θ , θ) may be expressed by the following equation. Note that a (θ) and c (θ) are attenuation coefficients. a (θ) is sometimes called a distance attenuation coefficient, and c (θ) is sometimes called a constant term. The attenuation coefficients a (θ) and c (θ) are both functions of θ determined by θ.
_{P θ = g θ (x θ} , θ) = a (θ) × logx θ + c (θ)

In this case, the calculation of the optimal solution for optimizing the objective function described above is the calculation of the attenuation coefficients a (θ) and c (θ). If the transmission power is included in the attenuation coefficient c (θ), P _θ indicates the received signal strength. If the transmission power is not included in the attenuation coefficient c (θ), P _θ indicates the path loss. Become. Further, when P _θ is _represented by the above equation, δ _i and E _θ are _represented by the following equations.
δ _i = P _i −a (θ) × log x _i −c (θ)

Note that by calculating the attenuation coefficients a (θ) and c (θ) that minimize such E _θ , the attenuation coefficients a (θ) and c (θ) of the function g _θ are reduced to a weighted minimum two. It will be estimated by multiplication. Therefore, the estimation unit 12 calculates the optimal solution for optimizing the objective function including the weight F (θ _i ) that decreases as the distance from the specific azimuth angle θ increases, so that the weighted least square method or the weighted minimum absolute value is obtained. Calculation of a (θ) and c (θ) using regression analysis such as a method may be performed. By calculating those attenuation coefficients, the attenuation characteristic function _Pθ is calculated.

Next, the weight function F (θ _i ) will be described. As described above, the weight function may be any as long as it is smaller as it is farther from the specific azimuth angle θ. For example, F ₁ (θ _i ) or F ₂ ( θ _i ) may be used. Note that, as described above, the weight function is a function including one or more parameters related to reduction. The parameter relating to reduction is a parameter that defines the degree of reduction. For example, when it is away from the direction of the specific azimuth angle θ, it is determined by the parameter whether it decreases rapidly or gently. In F ₁ (θ _i ), α and β are parameters that characterize how small F ₁ (θ _i ) is when θ _i leaves the specific azimuth angle θ. The parameters α and β are values in the range of 0 <α <1, β> 0. Further, since the observation information of the azimuth angle further away from the specific azimuth angle θ is used as the value of the parameter β increases, an upper limit such as β ≦ 180 (degrees) may be provided. F ₂ (θ _i ) is a weight based on the pass characteristic of the Butterworth filter, the parameter η is a cutoff angle, the parameter γ is a coefficient related to the cutoff rate, and the parameter M is an order. The parameters η, γ, and M are values in the ranges of η> 0, γ> 0, and M> 0. Moreover, it is good also as (eta) <= 180 (degree), and it is good also as M> = 1. In addition, | θ−θ _i | may be, for example, 0 ≦ | θ−θ _i | ≦ 180 (degrees).

The range of azimuth angles that affect the estimation of the attenuation characteristic function by adjusting the values of parameters α and β of F ₁ (θ _i ) and the values of parameters η, γ, and M of F ₂ (θ _i ). As a result, the estimation result of the attenuation characteristic function is different. Therefore, as described above, it is required to set the parameter value so that the attenuation characteristic function can be estimated appropriately. Since F ₂ (θ _i ) can set the cutoff rate and the like more finely, it is possible to set a weight with a higher degree of freedom.

Further, the attenuation characteristic function P _θ of the specific azimuth angle θ is fitted by the received signal intensity included in the observation information having the azimuth angle close to the specific azimuth angle θ. On the other hand, the attenuation characteristic function _Pθ is also affected by the received signal intensity included in the observation information having an azimuth angle away from the specific azimuth angle θ. Even if it exists only, it can be avoided that an inappropriate attenuation characteristic function is estimated.

As described above, when g _θ (x _θ , θ) = a (θ) × log x _θ + c (θ), a linear regression model is obtained, and an analytical least square method or minimum absolute value method is used. The optimum solution can be calculated by using the nonlinear regression model. However, in the case of a nonlinear regression model, for example, the attenuation characteristic function may be estimated by improving the approximate solution by iterative calculation.

[Estimation of attenuation characteristic function using frequency]
In this case, the set of observation information received by the receiving unit 11 is as follows. Note that x _i , θ _i , P _i , and N are the same as when no frequency is used. F _i is the frequency (MHz) of the radio wave in the i-th observation information, and is any one of K frequencies. Here, K is a positive integer less than or equal to N. When K = 2, for example, f ₁ = f ₂ =..., F ₃ = f ₄ =.
Set of observation information = {(x ₁ , θ ₁ , P ₁ , f ₁ ), (x ₂ , θ ₂ , P ₂ , f ₂ ),..., (X _N , θ _N , P _N , f _N )}

When the specific azimuth angle θ is set as in the case where the frequency is not used, an attenuation characteristic function P _θ (dBm) of the specific azimuth angle θ is expressed by the following equation. Note that f is the frequency (MHz) of the radio wave from the wave source 2.
P _θ = g _θ (x _θ , f, θ)

Therefore, the residual δ _i with respect to P _θ with respect to the received signal intensity P _i of the i-th observation information (x _i , θ _i , P _i , f _i ) is expressed by the following equation.
δ _i = P _i −g _θ (x _i , f _i , θ)
Note that the estimation unit 12 calculates _gθ , which is an optimal solution for optimizing the objective function _Eθ , for all observation information, as in the case where no frequency is used. Further, when using a frequency, g _θ (x _θ , f, θ) is expressed by the following equation, for example.

_{P θ = g θ (x θ} , f, θ) = a (θ) × logx θ + b × logf + c (θ)

Here, the attenuation coefficient b is a frequency coefficient. For example, when the radio wave propagation model from the wave source 2 to the receiving device 1 is a free space model, b = 20 may be set, and from the wave source 2 to the receiving device 1. of radio wave propagation model Okumura - when the Hata model (urban model) may be b = 26.16-1.1 × h _m +1.56. However, this model can be applied only when the following conditions are satisfied.
30 <h _b <200
1 <h _m <10
150 <f <2200
1 <x _i <20

_Here , h _b is the transmitting antenna height (m), _hm is the receiving antenna height (m), f is the frequency (MHz) of the radio wave, and x _i is from the wave source 2 to the receiving device 1. Distance (km). In this case, it is necessary to obtain the receive antenna height h _m. The reception antenna height h _m, for example, may be included in the observation information, or, in the attenuation coefficient estimating unit 3, a receiver identifier, the height of the antenna receiving apparatus 1 identified by the receiver identifier May be associated and stored in a recording medium (not shown). Note that the reception antenna height and the transmission antenna height may be reversed. That is, h _b may be the receiving antenna height (m), and _hm may be the transmitting antenna height (m). Moreover, since the transmitting antenna height is usually unknown, the Okumura-Kashiwa model may be applied on the assumption that the conditions regarding the transmitting antenna height are satisfied.

Therefore, also in this case, the calculation of the optimum solution for optimizing the objective function is the calculation of the attenuation coefficients a (θ) and c (θ). Further, when P _θ is _represented by the above equation, δ _i and E _θ are _represented by the following equations.
δ _i = P _i −a (θ) × log x _i −b × log f _i −c (θ)

The weight F (θ _i ) is the same as that when no frequency is used. For example, F ₁ (θ _i ) or F ₂ (θ _i ) may be used. In this way, even when the frequency is used, the attenuation characteristic function can be estimated by calculating the attenuation coefficients a (θ) and c (θ) that optimize the objective function _Eθ . In addition, when the frequency is also used, the number of samples increases because the function fitting can be performed using radio waves having different frequencies. Therefore, for example, even if the number of receiving apparatuses 1 is small, it is possible to estimate the attenuation characteristic function with higher accuracy.

In the above description, the frequency coefficient b is given from the model, but this need not be the case. When the frequency coefficient b is not given from the model, the attenuation characteristic function P _θ and the residual δ _i may be expressed by the following equations.
_{P θ = g θ (x θ} , f, θ) = a (θ) × logx θ + b (θ) × logf + c (θ)
δ _i = P _i −a (θ) × log x _i −b (θ) × log f _i −c (θ)
Then, attenuation coefficients a (θ), b (θ), and c (θ) that are optimum solutions for minimizing the objective function E _θ may be calculated. That is, the attenuation coefficient b (θ), which is a frequency coefficient, may also be calculated. Thus, estimating the attenuation coefficient of the attenuation characteristic function may be estimating all the attenuation coefficients a (θ), b (θ), c (θ), or a part of the attenuation coefficients. It may be that a (θ) and c (θ) are estimated. In the following description, the case where the attenuation characteristic function is estimated without using the frequency will be mainly described.

In the above description, the case where the attenuation characteristic function is the received signal strength has been described. However, when the transmission power of the wave source 2 can be known, the attenuation characteristic function indicating the path loss is calculated using the transmission power. Needless to say, it may be estimated. In this case, the attenuation characteristic function that is a path loss is “transmission power−P _θ ”. In the estimation method using the frequency, when the same wave source 2 transmits radio waves of different frequencies with the same transmission power, or when different wave sources 2 existing in close proximity have different frequency radio waves with the same transmission power. When transmitting via a transmission antenna having the same antenna gain, the attenuation characteristic function indicating the received signal strength can be calculated as described above. On the other hand, if not, the estimation unit 12 estimates the attenuation characteristic function indicating the path loss using the transmission power. As such, when transmission power is required for the estimation of the attenuation characteristic function, the transmission power may be estimated from, for example, received power or received signal strength, and is pre-registered from the wave source 2 or other devices. A value may be obtained. In addition, when estimating transmission power, the estimation part 12 may estimate transmission power using all the reception power of the some receiver 1 or the reception power more than a predetermined threshold value. And the estimation part 12 may estimate the attenuation characteristic function which shows a path loss using the estimated transmission power and the received signal strength of the receiver 1. FIG. When estimating the transmission power, the coefficient of a model (for example, a free space model, a ground reflection two-wave model, an Okumura-Kashiwa model, etc.) corresponding to the propagation path between the wave source 2 and the receiving device 1 is used. A path loss function G (x, f) = a × log (x) + b × log (f) + c using a, b, and c may be used. Here, x is the distance from the wave source 2 to the receiving device 1, and f is the frequency. The model may be selected using, for example, a delay profile acquired by the receiving device 1. For example, if the delay profile indicates that it is a line of sight, select a free-space model or a ground reflection two-wave model, and if the delay profile indicates that it is not a line of sight, select the Okumura-Hagi model. May be. Further, among the plurality of transmission powers calculated in this way, the maximum value may be the transmission power of the wave source 2, or the average + 3 × (standard deviation) may be the transmission power of the wave source 2. The standard deviation is a standard deviation of the calculated transmission power. The former is considered that the maximum transmission power is the actual transmission power because the transmission power calculated from the reception power received via the propagation path, which is an ideal line of sight, is considered to be the maximum value. is there. In the latter case, if the statistical variation is taken into account, the average + 3 × (standard deviation) is a value close to the maximum value, so that the value is regarded as the actual transmission power.

Moreover, the estimation part 12 shall perform the process which estimates an attenuation coefficient about several azimuth | direction (specific azimuth | direction angle) about several values of a parameter as mentioned above. A plurality of values of the parameter may be determined in advance. For example, if the weighting function is F ₁ (θ _i), a plurality of values of the parameters, (α, β) = ( α 1, β 1), (α 2, β 2), ..., (α A , Β _A ). A is an integer of 2 or more, and indicates the total number of sets of parameters α and β. Further, α _1, ..., may be present the same value α _{A, β 1,} ..., it may be present the same value beta _A. However, it is preferable that the same values do not exist as the parameter value pairs (α ₁ , β ₁ ), (α ₂ , β ₂ ),..., (Α _A , β _A ). As such, the estimation unit 12 acquires correspondence information that associates a parameter value with an attenuation coefficient for each of a plurality of azimuth angles, estimated using a weight function of the parameter value, for a plurality of parameter values. Will do. The estimation unit 12 accumulates the plurality of correspondence information in the storage unit 13. In addition, a plurality of pieces of correspondence information in the case of the parameters (α, β) included in the weight function are as follows, for example.
(Α ₁ , β ₁ ): {(a (θ), c (θ))}
(Α ₂ , β ₂ ): {(a (θ), c (θ))}
...
(Α _A , β _A ): {(a (θ), c (θ))}

Here, {(a (θ), c (θ))} = {(a (0 °), c (0 °)), (a (ε), c (ε)), (a (2ε), c (2ε)), (a (3ε), c (3ε)),..., (a (B × ε), c (B × ε))}. Also, {(a (θ), c (θ))} corresponding to different parameter sets is usually a different set. (Α _j , β _j ): {(a (θ), c (θ))} is one piece of correspondence information. Note that j is an arbitrary integer from 1 to A. Further, ε is a specific azimuth angle interval (deg). When the attenuation coefficient is estimated for each azimuth angle of 360 °, B is the smallest integer that satisfies ε × (B + 1) ≧ 360 °. Here, a set of attenuation coefficients of respective azimuth angles corresponding to the parameter values (α _j , β _j ) is represented by {(a (θ, α _j , β _j ), c (θ, α _j , β _j )). } May be described. In this case, {(a (θ, α _j , β _j ), c (θ, α _j , β _j ))} is one piece of correspondence information. That is, the plurality of pieces of correspondence information estimated by the estimation unit 12 are as follows, for example.
{(A (θ, α ₁ , β ₁ ), c (θ, α ₁ , β ₁ ))}
{(A (θ, α ₂ , β ₂ ), c (θ, α ₂ , β ₂ ))}
...
{( _A (θ, α _A , β _A ), c (θ, α _A , β _A ))}
Note that {(a (θ, α _j , β _j ), c (θ, α _j , β _j ))} = {(a (0 °, α _j , β _j ), c (0 °, α _j , β _j )), (a (ε, α _j , β _j ), c (ε, α _j , β _j )) _,.

  The storage unit 13 stores a plurality of pieces of correspondence information acquired by the estimation unit 12. As described above, the correspondence information is information that associates the parameter value with the attenuation coefficient for each of a plurality of azimuth angles. The storage in the storage unit 13 may be temporary storage in a RAM or the like, or may be long-term storage. The storage unit 13 can be realized by a predetermined recording medium (for example, a semiconductor memory, a magnetic disk, an optical disk, etc.). Here, “associating the parameter value with the attenuation coefficient for each of a plurality of azimuth angles” means that it is only necessary to obtain the attenuation coefficient for each of a plurality of azimuth angles from the parameter value. Therefore, the correspondence information may include information including a parameter value and an attenuation coefficient for each of a plurality of azimuth angles as a set, and is information for linking the parameter value and the attenuation coefficient for each of a plurality of azimuth angles. May be. In the latter case, the correspondence information may be, for example, information that associates a parameter value with a pointer or address indicating the position where the attenuation coefficient for each of a plurality of azimuth angles is stored. In the present embodiment, the former case will be mainly described. Further, the parameter value and the attenuation coefficient for each of a plurality of azimuth angles may not be directly associated with each other. For example, the third information may correspond to the parameter value, and the third information may correspond to attenuation coefficients for a plurality of azimuth angles. The same applies when other information is associated.

The reference information storage unit 14 stores a plurality of reference information. The reference information is information including a plurality of pieces of reference correspondence information and parameter correct answer values. The reference correspondence information includes a parameter value, a weight function of the parameter value, and an azimuth characteristic that is an azimuth characteristic of an attenuation coefficient for each of a plurality of azimuth angles estimated using a high-density observation set. Is information that associates. The high-density observation set is a set of observation information that is larger in number than the observation set. The observation set and the high-density observation set usually correspond to radio waves from different wave sources. However, as will be described later, the high-density observation set accepted according to the output of the request information corresponds to radio waves from the same wave source as the observation set. Different high-density observation sets usually correspond to radio waves from different wave sources. In addition, a plurality of pieces of reference correspondence information included in one piece of reference information is usually calculated using one high-density observation set, and the high-density observation set is different for each piece of reference information. Note that the method for estimating the attenuation coefficient for each of a plurality of azimuth angles using the high-density observation set is the same as the method for estimating the attenuation coefficient for each of a plurality of azimuth angles using the observation set described above. is there. However, when a high-density observation set is used, the number of pieces of observation information is large, so that a more accurate attenuation coefficient can be estimated. 5A and 5B are diagrams for explaining the observation set and the high-density observation set. For example, the set of observation information acquired by the receiving apparatus shown in FIG. 5A is an observation set, and the set of observation information acquired by the receiving apparatus shown in FIG. 5B is a high-density observation set. As can be seen from the comparison between the two figures, the high-density observation set includes observation information acquired at a receiving position with a higher density than the observation set. As a result, the number of elements in the high-density observation set is larger than the number of elements in the observation set. The azimuth angle characteristic of the attenuation coefficient may be, for example, the variance of the change in the azimuth direction of the attenuation coefficient, the standard deviation of the change in the azimuth direction of the attenuation coefficient, or the azimuth direction of the attenuation coefficient. Other information indicating the state of change may be used. In the present embodiment, the case where the azimuth angle characteristic of the attenuation coefficient is a variance of changes in the azimuth direction of the attenuation coefficient will be mainly described. The change in the azimuth direction of the attenuation coefficient may be, for example, a value obtained by differentiating the attenuation coefficient with respect to the azimuth angle, or may be a difference in attenuation coefficient between adjacent specific azimuth angles. For example, the differential ∂a (k × ε) / ∂θ at the azimuth angle of the attenuation coefficient may be as follows.
∂a (k × ε) / ∂θ = (a (k × ε) −a ((k−1) × ε)) / ε
Further, the difference D (k × ε) in the attenuation coefficient between adjacent specific azimuth angles may be as follows, for example.
D (k × ε) = a (k × ε) −a ((k−1) × ε)
Note that k is an arbitrary integer from 0 to B. However, ε is a divisor of 360 °, and a (−ε) = a (B × ε). The same applies to the attenuation coefficient c (θ). The correct value of the parameter included in the reference information is the value of the parameter that matches the high-density observation set corresponding to the plurality of reference correspondence information included in the reference information. The parameter suitable for the high-density observation set is the value of the parameter corresponding to the attenuation coefficient for each azimuth included in the attenuation characteristic function for each azimuth with a small error from multiple observation information included in the high-density observation set. It may be. That is, when the attenuation characteristic function for each of a plurality of azimuth angles is estimated using a weight function including the correct value of the parameter and a high-density observation set, the reception characteristics estimated using the attenuation characteristic function that is the estimation result The error between the signal strength and the received signal strength included in each piece of observation information of the high-density observation set is reduced. Specifically, the reference information includes correct parameter values (α ^c , β ^c ) and a plurality of _pieces of reference correspondence information {[σ _{∂a, ref} (α _j , β _j )] ² , [σ _{∂c, ref} (α _j , β _j )] ² }. In addition,
{[Σ _{∂a, ref} (α _j , β _j )] ² , [σ _{∂c, ref} (α _j , β _j )] ² } = {[σ _{∂a, ref} (α ₁ , β ₁ )] ² , [Σ _{∂c, ref} (α ₁ , β ₁ )] ² ,..., [Σ _{∂a, ref} (α _A , β _A )] ² , [σ _{∂c, ref} (α _A , β _A )] ² }
[Σ _{∂a, ref} (α ₁ , β ₁ )] ² and [σ _{∂c, ref} (α ₁ , β ₁ )] ² are one piece of reference correspondence information. [Σ _{∂a, ref} (α _j , β _j )] ² is the azimuth characteristic (variance) of the attenuation coefficient a (θ) corresponding to the parameter values (α _j , β _j ), and [σ _{∂c, ref} (α _j , β _j )] ² is the azimuth characteristic (dispersion) of the attenuation coefficient c (θ) corresponding to the parameter values (α _j , β _j ).

  The storage in the reference information storage unit 14 may be temporary storage in a RAM or the like, or may be long-term storage. The reference information storage unit 14 can be realized by a predetermined recording medium (for example, a semiconductor memory, a magnetic disk, an optical disk, etc.).

The similarity determination unit 15 acquires the azimuth angle characteristic of the attenuation coefficient for each parameter value using the plurality of correspondence information acquired by the estimation unit 12. The type of the azimuth angle characteristic is preferably the same as the type of the azimuth characteristic associated with the parameter value in the plurality of pieces of reference correspondence information included in the reference information. For example, in the reference correspondence information, when the azimuth characteristic associated with the parameter value is the variance of the change in the azimuth direction of the attenuation coefficient, the similarity determination unit 15 acquires the parameter information obtained using the correspondence information. It is also preferable that the azimuth angle characteristic of the attenuation coefficient for each value is a dispersion of changes in the azimuth direction of the attenuation coefficient. For example, the similarity determination unit 15 may calculate an azimuth angle characteristic that is a variance of changes in the azimuth angle direction of the attenuation coefficient as in the following equation.

Note that j is an arbitrary integer from 1 to A. The bar indicates an average value (for example, an average value of k = 0 to B such as ∂a (k × ε) / ∂θ) regarding the partial differentiation at the azimuth angle of the attenuation coefficient. The similarity determination unit 15 determines whether or not the azimuth characteristics for each parameter value related to the plurality of reference correspondence information included in the reference information are similar to the azimuth characteristics for each parameter value acquired in this way. This determination may be made based on, for example, whether or not a value obtained by accumulating a value corresponding to the absolute value of the difference between both angle characteristics for each parameter value is smaller than a predetermined threshold value. The value corresponding to the absolute value may be, for example, a value of an increasing function using the absolute value as an argument (for example, the absolute value itself or the square of the absolute value). The value obtained by accumulating the values corresponding to the absolute value of the difference between the two-angle characteristics for each parameter value may be, for example, the root mean squared error (RMSE) of the both-angle characteristics. Mean squared error (MSE) may be used, and other values indicating values obtained by accumulating values corresponding to the absolute value of the difference between both angular characteristics for each parameter value may be used. For example, when calculating RMSE, the similarity determination unit 15 calculates RMSE [∂a] that is the RMSE related to the attenuation coefficient a (θ) and RMSE [that is the RMSE related to the attenuation coefficient c (θ) as follows. ∂c] may be calculated.

  Then, for example, when RMSE [∂a] is less than or equal to the threshold and RMSE [∂c] is also less than or equal to the threshold, the similarity determination unit 15 determines that the azimuth characteristics corresponding to a plurality of pieces of correspondence information are the reference information May be determined to be similar to the azimuth angle characteristics corresponding to a plurality of pieces of reference correspondence information included in. Note that the threshold for RMSE [∂a] and the threshold for RMSE [∂c] may be the same or different. For example, when RMSE [∂a] + RMSE [∂c] is equal to or less than a threshold, the similarity determination unit 15 includes a plurality of pieces of reference correspondence information in which azimuth characteristics corresponding to a plurality of pieces of correspondence information are included in the reference information. May be determined to be similar to the azimuth angle characteristic corresponding to. In addition, the similarity determination unit 15 determines that the azimuth characteristics corresponding to a plurality of pieces of correspondence information are based on the reference information when the values of other functions having RMSE [∂a] and RMSE [∂c] as arguments are equal to or less than a threshold value. May be determined to be similar to the azimuth angle characteristics corresponding to a plurality of pieces of reference correspondence information included in. The similarity determination unit 15 performs the similarity determination for each reference information stored in the reference information storage unit 14. In the following description, the azimuth characteristic for each parameter value corresponding to a plurality of reference correspondence information included in the reference information is obtained for each parameter value corresponding to the plurality of correspondence information stored in the storage unit 13. When similar to the azimuth angle characteristic, the plurality of pieces of reference correspondence information included in the reference information may be similar to the plurality of pieces of correspondence information stored in the storage unit 13.

  The reference information storage unit 14 stores a plurality of pieces of information for associating a parameter value with an attenuation coefficient for each of a plurality of azimuths corresponding to the parameter value, and a plurality of pieces of reference information including correct parameter values. May be. Even in that case, when the similarity determination by the similarity determination unit 15 is performed, the azimuth characteristic of the attenuation coefficient is calculated for each parameter value from the plurality of pieces of information. Therefore, when the similarity determination is performed, the reference information storage unit 14 stores a plurality of pieces of reference information including a plurality of pieces of reference correspondence information and correct parameter values.

The specifying unit 16 sets the correct value of the parameter included in the reference information having the plurality of reference correspondence information determined to be similar to the azimuth angle characteristic for each parameter value corresponding to the plurality of correspondence information by the similarity determination unit 15. The attenuation coefficient associated with the correspondence information is specified. For example, the similarity determination unit 15 _performs a plurality of _pieces of reference correspondence information {[σ _{∂a, ref} (α _j , β _j )] ² , [σ _{∂c, ref} (α _j , β _j )] ² }, When it is determined that the correspondence information is similar and the correct value (α ^c , β ^c ) of the parameter is associated with the plurality of reference correspondence information, the specifying unit 16 determines the correct value (α of the parameter) ^c, the beta ^c), the attenuation coefficient associated with the corresponding information, namely, the damping coefficient ^{a (θ, α c, β} c), c (θ, α c, may identify the beta ^c). The specified attenuation coefficient is an attenuation coefficient for each of a plurality of azimuth angles. If there are two or more pieces of reference information having a plurality of pieces of reference correspondence information determined to be similar to the azimuth characteristics for each parameter value corresponding to a plurality of pieces of correspondence information, the specifying unit 16 specifies the attenuation coefficient. For this purpose, the correct value of the parameter included in the most similar reference information may be used, or the correct value of the parameter included in other reference information may be used. In the latter case, for example, the correct value of the parameter included in the reference information corresponding to the high-density observation set having the largest number of elements may be used, or the correct value of the parameter included in the randomly selected reference information May be used. If there is no plurality of reference correspondence information determined by the similarity determination unit 15 to be similar to the azimuth angle characteristics for each parameter value corresponding to the plurality of correspondence information, the specifying unit 16 You may specify the attenuation coefficient matched with the correct value of the parameter contained in the reference | standard information received by the reception part 23 by correspondence information. The reception of the reference information by the reference information receiving unit 23 will be described later. Note that the plurality of reference correspondence information determined to be similar to the azimuth characteristics for each parameter value corresponding to the plurality of correspondence information are strictly the azimuth characteristics for each parameter value corresponding to the plurality of correspondence information. Is a plurality of reference correspondence information that associates a plurality of azimuth characteristics determined to be similar to the parameter values. By specifying the attenuation coefficient by the specifying unit 16, the attenuation characteristic function is specified as a result. The specified attenuation coefficient may be, for example, that the specified attenuation coefficient is stored in a recording medium (not shown), or a flag indicating that the specified attenuation coefficient is specified. Information may be set.

The range estimation unit 17 estimates the range in which the radio wave from the wave source 2 reaches using the attenuation characteristic function including the attenuation coefficient specified by the specifying unit 16. For example, the range estimation unit 17 uses an attenuation characteristic function for each of a plurality of azimuth angles including the specified attenuation coefficient a (θ, α ^c , β ^c ), c (θ, α ^c , β ^c ), You may estimate the range which the electromagnetic wave from the wave source 2 reaches | attains. The range may be, for example, a range where radio waves from the wave source 2 can be used, or a range affected by radio waves from the wave source 2. When the wave source 2 is a mobile phone base station, for example, the former range is a range in which a mobile phone call can be performed, and the latter range may not be a mobile phone call. It may be in a range where radio waves having the same frequency cannot be used for other purposes. In addition, when it can be considered that the area | region other than this range is a white space, it can also be considered that the range estimation part 17 is estimating the white space substantially. The white space is a regional area where radio waves from the wave source 2 do not reach. The range estimation unit 17 uses the attenuation characteristic function estimated by the estimation unit 12 to determine the distance from the wave source 2 at which the received signal power becomes a predetermined threshold value for each specific direction in which the attenuation characteristic function is estimated. A region connecting the reaching ends of the radio waves that are calculated and points according to the distance may be set as a range where the radio waves reach. Specifically, when the attenuation characteristic function related to the specific azimuth angle θ is estimated, the position of the distance d at which the received signal strength becomes the threshold value P ^TH may be set as the radio wave arrival end. In this way, a plurality of sets of the specific azimuth angle θ and the distance d to the radio wave arrival end can be acquired. When the attenuation characteristic function does not indicate the received signal power, the range estimation unit 17 may also estimate the range using the transmission power of the wave source 2.

  6A and 6B are diagrams illustrating an example of a radio wave reachable range. The boundary of the radio wave arrival range may pass through each of the radio wave arrival ends as shown in FIG. 6A, or may not be as shown in FIG. 6B. In the latter case, for example, the range estimation unit 17 uses a set of the specific azimuth angle θ and the distance d acquired in the coordinate system with the horizontal axis as the azimuth and the vertical axis as the reach of the radio wave (θ, d) is plotted. And what corresponds to the curve specified so that the distance between the plotted point and the curve may be the closest may be the boundary line of the radio wave reachable range. The radio wave arrival distance is the distance from the wave source 2 to the radio wave arrival end. When the wave source 2 transmits radio waves having a plurality of frequencies, the range estimation unit 17 may estimate the reach of radio waves for each frequency. Moreover, the range estimation part 17 may perform the process which specifies a white space separately. When the number of the wave sources 2 is one, as described above, it is possible to specify the white space as a result by specifying the reach range of the radio wave, but when there are a plurality of wave sources 2, A range in which radio waves from any wave source 2 do not reach is white space. Therefore, the range estimation unit 17 may specify a white space that is an area that is not included in any radio wave reachable range. As a result, as long as it is possible to distinguish the radio wave reachable range and white space from the other radio wave reachable areas and white spaces, there is no limitation on the method for specifying the radio wave reachable range or white space. For example, the range estimation unit 17 may acquire information indicating the outline of a region such as a radio wave reachable range.

  The output unit 18 performs output related to the range estimated by the range estimation unit 17. The output may be, for example, outputting information indicating a radio wave reachable range or white space, or outputting a determination result as to whether a certain position is included in the radio wave reachable range or white space. It may be. In the case of outputting the determination result, for example, the output unit 18 may make a determination using the estimation result obtained by the range estimation unit 17, or another component may make the determination. Note that the position to be determined may be received by the receiving unit 11, for example.

  Here, the output may be, for example, display on a display device (for example, a CRT or a liquid crystal display), transmission via a communication line to a predetermined device, printing by a printer, or output to a recording medium. It may be accumulated or delivered to another component. Note that the output unit 18 may or may not include a device that performs output (for example, a display device or a transmission device). The output unit 18 may be realized by hardware, or may be realized by software such as a driver that drives these devices.

  The request information output unit 19 determines the reference regarding the radio wave from the wave source 2 when there is no plurality of reference correspondence information determined by the similarity determination unit 15 to be similar to the azimuth angle characteristic for each parameter value corresponding to the plurality of correspondence information. Outputs request information for requesting information. The wave source 2 is a radio wave source 2 corresponding to each piece of observation information included in the observation set. The request information may include information that can identify the wave source 2. This is because a person who has received the output request information can specify the wave source 2 from which the reference information is acquired. The information that can specify the wave source 2 may be, for example, the position of the wave source 2 or the ID of the wave source 2. Information that can specify the wave source 2 may be received together with the observation set, may be generated by the attenuation coefficient estimation device 3, or may be acquired by other methods.

  Here, the output may be, for example, display on a display device (for example, a CRT or a liquid crystal display), transmission via a communication line to a predetermined device, printing by a printer, or audio output by a speaker. Alternatively, it may be stored in a recording medium or delivered to another component. The request information output unit 19 may or may not include an output device (for example, a display device or a printer). Further, the request information output unit 19 may be realized by hardware, or may be realized by software such as a driver that drives these devices.

  The high-density observation set receiving unit 20 receives a high-density observation set related to radio waves from the wave source in response to the output of request information by the request information output unit 19. The high-density observation set may or may not include each element of the observation set received by the receiving unit 11. Each piece of observation information included in the high-density observation set may be acquired by moving the movable receiving device 1 to a plurality of locations around the wave source 2, or may be installed in advance. It may be acquired by a plurality of receiving devices 1. The high-density observation set receiving unit 20 may receive a plurality of pieces of observation information included in one high-density observation set in a batch or may be received separately.

  The high-density observation set reception unit 20 may receive a high-density observation set input from an input device (for example, a keyboard, a mouse, a touch panel, etc.), for example. A density observation set may be received, or a high-density observation set read from a predetermined recording medium (for example, an optical disk, a magnetic disk, or a semiconductor memory) may be received. Note that the high-density observation set reception unit 20 may or may not include a device (for example, a modem or a network card) for reception. In addition, the high-density observation set reception unit 20 may be realized by hardware, or may be realized by software such as a driver that drives a predetermined device.

The reference estimation unit 21 uses a weight function and the high-density observation set received by the high-density observation set reception unit 20 to estimate a parameter value and a plurality of values estimated using the weight function of the parameter value. Information associating the attenuation coefficient for each azimuth is acquired for the values of a plurality of parameters. The attenuation coefficient for each of the plurality of azimuth angles is, for example, as follows.
{(A _ref (θ, α ₁ , β ₁ ), c _ref (θ, α ₁ , β ₁ ))}
{(A _ref (θ, α ₂ , β ₂ ), c _ref (θ, α ₂ , β ₂ ))}
...
{( _{A ref} (θ, α _A , β _A ), c _ref (θ, α _A , β _A ))}
Note that {(a _ref (θ, α _j , β _j ), c _ref (θ, α _j , β _j ))} = {(a _ref (0 °, α _j , β _j ), c _ref (0 ° , Α _j , β _j )), (a _ref (ε, α _j , β _j ), c _ref (ε, α _j , β _j )) _,.

Thereafter, the reference estimation unit 21 acquires a plurality of reference correspondence information by acquiring the azimuth angle characteristics of the attenuation coefficient for each of the plurality of azimuth angles. The method by which the reference estimation unit 21 acquires the azimuth angle characteristics is the same as the method by which the similarity determination unit 15 acquires the azimuth angle characteristics except that the observation set is a high-density observation set, and detailed description thereof is omitted. . In addition, the type of azimuth characteristic acquired by the reference estimation unit 21 is preferably the same as the type of azimuth characteristic acquired by the similarity determination unit 15 for a plurality of pieces of correspondence information. Its azimuth angle characteristics, if the variance of the change in the azimuth angle direction of the damping coefficient, for example, reference estimation unit 21, the values of the parameters (α _j, β _j) for, [sigma _{∂a, ref} ( α _j , β _j )] ² , [σ _{∂c, ref} (α _j , β _j )] ² may be calculated. The calculation of [σ _{∂a, ref} (α _j , β _j )] ^2, etc., except that a (θ, α _j , β _j ) etc. becomes a _ref (θ, α _j , β _j ) etc. The calculation is performed in the same manner as the calculation by the similarity determination unit 15.

The correct value specifying unit 22 receives the high density received by the high density observation set receiving unit 20 from the plurality of information obtained by the reference estimating unit 21 and associating the parameter value with the attenuation coefficient for each of a plurality of azimuth angles. Attenuation coefficients for each of a plurality of azimuth angles that match the observation set are specified, and a correct value that is a parameter value corresponding to the specified attenuation characteristics is specified. For example, for each parameter value, the correct value specifying unit 22 includes the received signal strength included in the observation information and the parameter value regarding the observation position (reception position) of each observation information included in the high-density observation set. An error from the received signal strength calculated using the attenuation characteristic function estimated using the weight function may be calculated, and the parameter value having the smallest error may be set as the correct value. For example, the correct value specifying unit 22 uses {(a _ref (θ, α _j , β _j ), c _ref (θ, α _j , β _j ))} for the parameter values (α _j , β _j ). The received signal strength at each observation position is calculated. When calculating the received signal strength at a certain observation position, an attenuation characteristic function including an attenuation coefficient (a _ref , c _ref ) of a specific azimuth angle closest to the azimuth angle of the observation position may be used. Further, the correct answer value specifying unit 22 calculates an error between the two by accumulating a value corresponding to the absolute value of the difference between the observed received signal strength and the calculated received signal strength for each observation position. . The value corresponding to the absolute value may be, for example, a value of an increasing function using the absolute value as an argument (for example, the absolute value itself or the square of the absolute value). The error may be, for example, RMSE or MSE. The correct answer value specifying unit 22 calculates such an error for each parameter value. As a result, a parameter value and an error corresponding to the parameter value are obtained. Thereafter, the correct value specifying unit 22 may set the parameter value corresponding to the smallest error as the correct value of the parameter. The correct value of the parameter may be, for example, (α ^c , β ^c ). Note that the correct answer value specifying unit 22 may specify the parameter value corresponding to the attenuation coefficient for each of a plurality of azimuth angles suitable for the high-density observation set without actually calculating such an error. In that case, for example, the correct value specifying unit 22 uses the set {a _ref (θ, α _{j) in the} information obtained by the reference estimating unit 21 to associate the parameter value and the attenuation coefficient for each of a plurality of azimuth angles. , Β _j )} = {a _ref (0 °, α _j , β _j ), a _ref (ε, α _j , β _j ),..., A _ref (B × ε, α _j , β _j )} Parameters (α _j , β _j ) corresponding to an attenuation coefficient {a _ref (θ, α _j , β _j )} having elements of −20 or less and high angular resolution (α _j , β _j ) May be specified as the correct answer value. In free space, the power of radio waves is inversely proportional to the square of the distance from the wave source, so the attenuation coefficient a _ref (θ) is −20. Since it is considered that attenuation is larger than that in free space, each element of the attenuation coefficient {a _ref (θ, α _j , β _j )} is considered to be −20 or less. Therefore, it is considered that an attenuation coefficient that does not match the high-density observation set can be excluded by excluding an attenuation coefficient that is not so. When the weight function is F ₁ (θ _i ), the smaller the value of the parameter α, the higher the angular resolution. Therefore, the correct answer value specifying unit 22 may use, for example, a small parameter α as the correct answer value.

In response to the output of the request information from the request information output unit 19, the reference information reception unit 23 uses a plurality of references acquired by the reference estimation unit 21 using the high-density observation set received by the high-density observation set reception unit 20. The reference information including the correspondence information and the correct value specified by the correct value specifying unit 22 is received. It may be considered that receiving a plurality of pieces of reference correspondence information from the reference estimation unit 21 and receiving correct parameter values from the correct value specifying unit 22 is reception of reference information including both. The reference information receiving unit 23 accumulates the reference information in the reference information storage unit 14. For example, the reference information receiving unit 23 receives a plurality of _pieces of reference correspondence information {[σ _{∂a, ref} (α _j , β _j )] ² , [σ _{∂c, ref} (α _j , β _j ) from the reference estimation unit 21. ] ² } may be received, the correct value (α ^c , β ^c ) of the parameter may be received from the correct value specifying unit 22, and reference information having both may be accumulated in the reference information storage unit 14.

  The reference information receiving unit 23 receives reference information about the radio wave from the wave source 2 from the outside of the attenuation coefficient estimation device 3 in response to the output of the request information by the request information output unit 19 and accumulates it in the reference information storage unit 14. May be. In this case, the attenuation coefficient estimation device 3 may not include the high-density observation set reception unit 20, the reference estimation unit 21, and the correct answer value specification unit 22. That is, the processing performed by these components may be performed by a device different from the attenuation coefficient estimation device 3. In this case, the reference information receiving unit 23 may receive the reference information transmitted via, for example, a wired or wireless communication line, and a predetermined recording medium (for example, an optical disk, a magnetic disk, or a semiconductor) Reference information read from a memory or the like may be received. Note that the reference information receiving unit 23 may or may not include a device (for example, a modem or a network card) for receiving. The reference information receiving unit 23 may be realized by hardware, or may be realized by software such as a driver that drives a predetermined device.

  The storage unit 13 and the reference information storage unit 14 may be realized by the same recording medium, or may be realized by separate recording media. In the former case, an area storing a plurality of pieces of correspondence information acquired by the estimation unit 12 is the storage unit 13, and an area storing a plurality of reference information is the reference information storage unit 14.

Next, the operation of the attenuation coefficient estimation device 3 will be described using the flowchart of FIG.
(Step S101) The reception unit 11 determines whether an observation set has been received. If accepted, the process proceeds to step S102. If not, the process of step S101 is repeated until an observation set is accepted.

  (Step S <b> 102) The estimation unit 12 acquires a plurality of pieces of correspondence information using the accepted observation set and accumulates them in the storage unit 13. Details of this processing will be described later with reference to the flowchart of FIG. 4A.

  (Step S103) The similarity determination unit 15 determines, for each reference information, whether or not the plurality of pieces of reference correspondence information included in the reference information is similar to the plurality of pieces of correspondence information stored in the storage unit 13. Details of this processing will be described later with reference to the flowchart of FIG. 4B.

  (Step S <b> 104) The specifying unit 16 determines whether there are a plurality of pieces of reference correspondence information similar to the plurality of pieces of correspondence information stored in the storage unit 13. If such a plurality of reference correspondence information exists, the process proceeds to step S105, and if not, the process proceeds to step S108.

  (Step S <b> 105) The specifying unit 16 specifies the correct value of the parameter included in the reference information having a plurality of pieces of reference correspondence information similar to the plurality of pieces of correspondence information stored in the storage unit 13. And the specific | specification part 16 specifies the attenuation coefficient for every several azimuths matched with the correct value of the specified parameter by several corresponding | compatible information. When there are a plurality of pieces of reference information having a plurality of pieces of reference correspondence information similar to the pieces of correspondence information stored in the storage unit 13, the specifying unit 16 specifies one piece of reference information as described above. The correct value of the parameter included in the reference information is used. When the process proceeds from step S112 to step S105, the specifying unit 16 uses the correct value of the parameter included in the reference information accumulated in step S112.

  (Step S <b> 106) The range estimation unit 17 estimates the radio wave arrival range using the attenuation characteristic function that is specified by the specification unit 16 and includes attenuation coefficients for each of a plurality of azimuth angles. The radio wave reachable range as the estimation result may be stored in a recording medium (not shown).

  (Step S <b> 107) The output unit 18 performs an output related to the range estimation result by the range estimation unit 17. Then, a series of processes relating to estimation of the reach of radio waves ends.

  (Step S108) The request information output unit 19 outputs request information. The request information may include, for example, information that can specify the wave source 2. Note that, according to the output of the request information, a high-density observation set including observation information with a higher density than the observation set is acquired for the radio wave transmitted from the wave source 2. This acquisition is performed by actually receiving a radio wave from the wave source 2 at a high-density observation point. Note that the wave source 2 may be specified by information included in the request information, for example.

  (Step S109) The high-density observation set receiving unit 20 determines whether a high-density observation set has been received. If accepted, the process proceeds to step S110. If not, the process of step S109 is repeated until accepted.

  (Step S110) The reference estimation unit 21 acquires a plurality of pieces of reference correspondence information using the received high-density observation set. Details of this process will be described later with reference to the flowchart of FIG. 4C.

  (Step S111) The correct value specifying unit 22 specifies the correct value of the parameter corresponding to the accepted high-density observation set. Details of this processing will be described later with reference to the flowchart of FIG. 4D.

  (Step S112) The reference information receiving unit 23 receives reference information including a plurality of pieces of reference correspondence information acquired in step S110 and the correct value of the parameter specified in step S111, and the reference information is stored in the reference information storage unit. 14 accumulate. Then, the process proceeds to step S105.

  Note that white space may be detected in step S106 of the flowchart of FIG. Further, by repeatedly executing the processing of the flowchart of FIG. 3, it is possible to detect the reach of the radio wave and the white space in the time direction. In the flowchart of FIG. 3, the case where the reference information is generated when there is no plurality of pieces of reference correspondence information similar to the plurality of pieces of correspondence information has been described. However, the reference information is also generated in other cases. It may be broken. For example, the reference information may be generated in order to accumulate a plurality of reference information in the reference information storage unit 14 in advance before the range of radio waves is estimated by the attenuation coefficient estimation apparatus 3 according to the present embodiment. .

FIG. 4A is a flowchart showing details of the processing (step S102) for acquiring a plurality of correspondence information in the flowchart of FIG.
(Step S201) The estimation unit 12 sets the parameter value to a predetermined initial value.

  (Step S202) The estimation unit 12 sets a specific azimuth angle θ, which is an azimuth angle indicating a specific direction, to 0 degrees.

  (Step S203) The estimation unit 12 estimates an attenuation coefficient related to the specific azimuth angle θ using a plurality of pieces of observation information included in the observation set. This estimation may or may not use frequency.

  (Step S204) The estimating unit 12 increments the specific azimuth angle θ by ε. Note that ε may or may not be a divisor of 360 degrees.

  (Step S205) The estimating unit 12 determines whether or not the specific azimuth angle θ is 360 degrees or more. If it is 360 degrees or more, the process proceeds to step S206; otherwise, the process returns to step S203. Information that associates the parameter values set in step S201 or step S207 with the attenuation coefficient estimated for each azimuth angle in step S203 is correspondence information. The correspondence information may be sequentially stored in the storage unit 13.

  (Step S206) The estimation unit 12 determines whether or not processing for acquiring correspondence information has been performed for all predetermined parameter values. If the correspondence information has been acquired for all parameter values, the process returns to the flowchart of FIG. 3, and if not, the process proceeds to step S207.

  (Step S207) The estimation unit 12 sets the value of the parameter to the next value of the current parameter value. How to change the value of the parameter may be determined in advance. Then, the process returns to step S202.

FIG. 4B is a flowchart showing details of the similarity determination process (step S103) in the flowchart of FIG.
(Step S <b> 301) The similarity determination unit 15 acquires an azimuth angle characteristic for each of the plurality of pieces of correspondence information stored in the storage unit 13. For example, when there are two or more types of attenuation coefficients for each of a plurality of azimuth angles, such as the attenuation coefficients a and c, the similarity determination unit 15 acquires azimuth angle characteristics for each type of attenuation coefficient. Also good. As a result, for example, the azimuth characteristics are acquired for each parameter value and each attenuation coefficient a and c.

  (Step S302) The similarity determining unit 15 sets a counter i to 1.

  (Step S303) The similarity determination unit 15 resembles a plurality of pieces of reference correspondence information included in the i-th reference information stored in the reference information storage unit 14 and a plurality of pieces of correspondence information stored in the storage unit 13. Similar information indicating the degree of the is calculated. The similarity information only needs to be information that allows the degree of similarity to be known as a result. For example, the similarity information may be similarity or dissimilarity. The similar information may be, for example, the aforementioned RMSE or MSE.

  (Step S304) The similarity determination unit 15 determines whether the two are similar based on the similarity information acquired in step S303. And when both are similar, it returns to the flowchart of FIG. 3, and when that is not right, it progresses to step S305. This determination may be made, for example, by comparing a value indicated by the similar information with a predetermined threshold value. If it is determined in step S304 that they are similar, it is determined that the plurality of reference correspondence information included in the i-th reference information and the plurality of correspondence information are similar. .

  (Step S305) The similarity determination unit 15 increments the counter i by 1.

  (Step S306) The similarity determination unit 15 determines whether or not the i-th reference information is stored in the reference information storage unit 14. If the i-th reference information is stored, the process returns to step S303. Otherwise, the process returns to the flowchart of FIG.

  In the flowchart of FIG. 4B, the case has been described in which the process returns to the flowchart of FIG. 3 when it is determined in step S <b> 304 that it is similar. After all the reference information is determined, the process may return to the flowchart of FIG.

FIG. 4C is a flowchart showing details of a process (step S110) for acquiring a plurality of reference correspondence information in the flowchart of FIG.
(Step S401) The reference estimation unit 21 sets a parameter value to a predetermined initial value.

  (Step S402) The reference estimation unit 21 sets a specific azimuth angle θ, which is an azimuth angle indicating a specific direction, to 0 degrees.

  (Step S403) The reference estimation unit 21 estimates an attenuation coefficient related to the specific azimuth angle θ using a plurality of pieces of observation information included in the high-density observation set. This estimation may or may not use frequency.

  (Step S404) The reference estimation unit 21 increments the specific azimuth angle θ by ε. Note that ε may or may not be a divisor of 360 degrees.

  (Step S405) The reference estimation unit 21 determines whether or not the specific azimuth angle θ is 360 degrees or more. If it is 360 degrees or more, the process proceeds to step S406. If not, the process returns to step S403.

  (Step S406) The reference estimation unit 21 acquires azimuth angle characteristics related to the plurality of attenuation characteristics using the attenuation coefficient estimated for each azimuth angle in Step S403. Then, the reference estimation unit 21 has acquired reference correspondence information that associates the parameter value set in step S401 or step S408 with the acquired azimuth angle characteristic. The reference correspondence information may be stored on a recording medium (not shown). When there are two or more types of attenuation coefficients for each of a plurality of azimuth angles, such as the attenuation coefficients a and c, the reference estimation unit 21 may acquire the azimuth angle characteristics for each type of attenuation coefficient. .

  (Step S407) The reference estimation unit 21 determines whether or not processing for acquiring reference correspondence information has been performed for all predetermined parameter values. If reference correspondence information has been acquired for all parameter values, the process returns to the flowchart of FIG. 3, and if not, the process proceeds to step S408.

  (Step S408) The reference estimation unit 21 sets the parameter value to a value next to the current parameter value. How to change the value of the parameter may be determined in advance. Then, the process returns to step S402.

FIG. 4D is a flowchart showing details of the parameter correct value acquisition process (step S111) in the flowchart of FIG.
(Step S501) The correct value specifying unit 22 sets the parameter value to a predetermined initial value.

  (Step S502) The correct answer value specifying unit 22 uses the attenuation characteristic function including the attenuation coefficient associated with the current parameter setting value according to the reference correspondence information, and the distance of each observation information included in the high-density observation set and The received signal strength corresponding to the azimuth is calculated. As a result, the received signal strength at the observation point corresponding to each observation information is calculated. When the attenuation coefficient is not estimated for the azimuth angle included in the observation information, the correct value specifying unit 22 determines, for example, the attenuation coefficient of the specific azimuth angle closest to the azimuth angle included in the observation information. It may be used to calculate the received signal strength.

  (Step S503) The correct answer value specifying unit 22 calculates the error between the received signal strength included in each observation information of the high-density observation set and the received signal strength for each observation point calculated in Step S502. To do. Specifically, the correct answer value specifying unit 22 may calculate RMSE, MSE, etc. for both received signal strengths. As a result of the calculation of the error, the correspondence between the parameter value and the error is acquired.

  (Step S504) The correct answer value specifying unit 22 determines whether or not errors have been calculated for all predetermined parameter values. If errors have been calculated for all parameter values, the process proceeds to step S505. If not, the process proceeds to step S506.

  (Step S505) The correct value specifying unit 22 sets the parameter value corresponding to the minimum error as the correct value of the parameter. And it returns to the flowchart of FIG.

  (Step S506) The correct value specifying unit 22 sets the parameter value to the value next to the current parameter value. How to change the value of the parameter may be determined in advance. Then, the process returns to step S502.

  As described above, according to the attenuation coefficient estimation device 3 according to the present embodiment, when there are a plurality of pieces of reference correspondence information similar to a plurality of pieces of correspondence information, correct values of parameters corresponding to the pieces of reference correspondence information are obtained. By using it, an appropriate attenuation coefficient can be estimated from an observation set having a small number of elements. As a result, it is possible to accurately estimate the reach of radio waves and the white space. In addition, when such reference correspondence information does not exist, an observation set is received by receiving a high-density observation set and obtaining new reference information using the high-density observation set according to the output of the request information. The attenuation coefficient corresponding to can be estimated appropriately. In addition, new reference information is accumulated and the number of reference information increases, thereby increasing the possibility of estimating the attenuation coefficient without outputting request information from a plurality of correspondence information corresponding to the accepted observation set. Can do. When the attenuation characteristic function indicates the received signal strength, the reception signal at each position can be obtained by using the attenuation characteristic function including the attenuation coefficient as an estimation result without knowing the transmission power of the wave source 2. The intensity can be estimated.

  In the present embodiment, the case where the attenuation coefficient estimation device 3 includes the range estimation unit 17 has been described, but this need not be the case. For example, when the range estimation is performed by another device, the attenuation coefficient estimation device 3 may not include the range estimation unit 17. In that case, for example, the output unit 18 may output the attenuation coefficient estimated by the estimation unit 12 or an attenuation characteristic function including the attenuation coefficient.

  Further, in the present embodiment, the case where the attenuation coefficient estimation device 3 includes the request information output unit 19 and the reference information reception unit 23 has been described, but this need not be the case. When new reference information is not received, the attenuation coefficient estimation device 3 may not include the request information output unit 19 and the reference information reception unit 23. In addition, when the reference information receiving unit 23 is not provided, the attenuation coefficient estimation device 3 may not include the high-density observation set receiving unit 20, the reference estimating unit 21, and the correct answer value specifying unit 22. When new reference information is not accepted, for example, errors such as RMSE between the plurality of correspondence information and the plurality of reference correspondence information are all larger than the threshold value, and the similarity determination unit 15 determines that the plurality of correspondence information If it is determined that a plurality of similar reference correspondence information does not exist, the specifying of the attenuation coefficient by the specifying unit 16 is not performed. Therefore, the similarity determination unit 15 may use a plurality of pieces of reference correspondence information most similar to the plurality of pieces of correspondence information as a plurality of pieces of reference correspondence information similar to the pieces of correspondence information. That is, there may be at least a plurality of pieces of reference correspondence information determined to be similar to a plurality of pieces of correspondence information by the similarity determination unit 15.

  In the above embodiment, each process or each function may be realized by centralized processing by a single device or a single system, or may be distributedly processed by a plurality of devices or a plurality of systems. It may be realized by doing.

  In the above embodiment, the information exchange between the components is performed by one component when, for example, the two components that exchange the information are physically different from each other. It may be performed by outputting information and receiving information by the other component, or when two components that exchange information are physically the same, one component May be performed by moving from the phase of the process corresponding to to the phase of the process corresponding to the other component.

  In the above embodiment, information related to processing executed by each component, for example, information received, acquired, selected, generated, transmitted, or received by each component In addition, information such as threshold values, mathematical formulas, addresses, and the like used by each constituent element in processing may be temporarily or for a long time held in a recording medium (not shown), even if not specified in the above description. Further, the storage of information on the recording medium (not shown) may be performed by each component or a storage unit (not shown). Further, reading of information from the recording medium (not shown) may be performed by each component or a reading unit (not shown).

  In the above embodiment, when information used by each component, for example, information such as a threshold value, an address, and various setting values used by each component may be changed by the user, Even if it is not specified in the description, the user may be able to change the information as appropriate, or may not be so. If the information can be changed by the user, the change is realized by, for example, a not-shown receiving unit that receives a change instruction from the user and a changing unit (not shown) that changes the information in accordance with the change instruction. May be. The change instruction received by the receiving unit (not shown) may be received from an input device, information received via a communication line, or information read from a predetermined recording medium, for example. .

  In the above embodiment, when two or more components included in the attenuation coefficient estimation apparatus 3 include a communication device, an input device, and the like, the two or more components have a physically single device. Or may have separate devices.

  In the above-described embodiment, each component may be configured by dedicated hardware, or a component that can be realized by software may be realized by executing a program. For example, each component can be realized by a program execution unit such as a CPU reading and executing a software program recorded on a recording medium such as a hard disk or a semiconductor memory. At the time of execution, the program execution unit may execute the program while accessing the storage unit or the recording medium. In addition, the software which implement | achieves the attenuation coefficient estimation apparatus 3 in the said embodiment is the following programs. In other words, this program sets a computer that can access the reference information storage unit to a set of a plurality of pieces of observation information having a received signal intensity of a radio wave received from the wave source by the receiving device, and a distance and an azimuth angle from the wave source to the receiving device. A reception unit that accepts an observation set, a function related to the attenuation characteristics of a radio wave from a wave source with respect to a specific azimuth, and an attenuation coefficient that is a function of an attenuation characteristic function that is a function depending on a distance from the wave source. Azimuth away from a specific azimuth by using a plurality of observation information included in and a weight function that is a function of weight that decreases as the distance from the specific azimuth increases, and that includes one or more parameters related to the decrease By performing the regression analysis, which has a smaller effect on the observation information including the angle, for multiple azimuth angles and multiple parameter values, The estimation unit that acquires the correspondence information that associates the parameter values with the attenuation coefficients for each of the plurality of azimuth angles, estimated using the weight function of the parameter values, and the plurality of parameters acquired by the estimation unit. Using the correspondence information, acquire the azimuth characteristics of the attenuation coefficient for each parameter value, and use the parameter value, the weight function of the parameter value, and the observation set as the azimuth characteristic for each acquired parameter value. Multiple reference correspondence information that correlates azimuth characteristics, which are characteristics of the azimuth direction of the attenuation coefficient for each azimuth angle, estimated using a high-density observation set that is a collection of a large number of observation information, and high A plurality of pieces of reference correspondence information included in the reference information stored in the reference information storage unit that stores a plurality of pieces of reference information including correct values that are values of parameters suitable for the density observation set A plurality of reference correspondences determined to be similar to the azimuth characteristics for each parameter value corresponding to a plurality of correspondence information by a similarity determination unit for determining whether the azimuth characteristics for each parameter value are similar. It is a program for causing a correct value of a parameter included in reference information having information to function as a specifying unit that specifies an attenuation coefficient associated with correspondence information.

  In the program, the functions realized by the program do not include functions that can be realized only by hardware. For example, the functions that can be realized only by hardware such as a modem and an interface card in the reception unit that receives information, the acquisition unit that acquires information, and the output unit that outputs information are included in at least the functions realized by the program. Absent.

  Further, this program may be executed by being downloaded from a server or the like, and a program recorded on a predetermined recording medium (for example, an optical disk such as a CD-ROM, a magnetic disk, a semiconductor memory, or the like) is read out. May be executed by Further, this program may be used as a program constituting a program product.

  Further, the computer that executes this program may be singular or plural. That is, centralized processing may be performed, or distributed processing may be performed.

  FIG. 7 is a schematic diagram showing an example of the appearance of a computer that executes the program and realizes the attenuation coefficient estimation apparatus 3 according to the embodiment. The above-described embodiment can be realized by computer hardware and a computer program executed on the computer hardware.

  7, the computer system 900 includes a computer 901 including a CD-ROM drive 905, a keyboard 902, a mouse 903, and a monitor 904.

  FIG. 8 is a diagram showing an internal configuration of the computer system 900. In FIG. 8, in addition to the CD-ROM drive 905, a computer 901 is connected to an MPU (Micro Processing Unit) 911, a ROM 912 for storing a program such as a bootup program, and the MPU 911, and receives instructions of an application program. A RAM 913 that temporarily stores and provides a temporary storage space, a hard disk 914 that stores application programs, system programs, and data, and a bus 915 that interconnects the MPU 911, the ROM 912, and the like are provided. The computer 901 may include a network card (not shown) that provides connection to a LAN, WAN, or the like.

  A program that causes the computer system 900 to execute the function of the attenuation coefficient estimation apparatus 3 according to the above-described embodiment may be stored in the CD-ROM 921, inserted into the CD-ROM drive 905, and transferred to the hard disk 914. Instead, the program may be transmitted to the computer 901 via a network (not shown) and stored in the hard disk 914. The program is loaded into the RAM 913 when executed. The program may be loaded directly from the CD-ROM 921 or the network. Further, the program may be read into the computer system 900 via another recording medium (for example, a DVD) instead of the CD-ROM 921.

  The program does not necessarily include an operating system (OS) or a third-party program that causes the computer 901 to execute the function of the attenuation coefficient estimation apparatus 3 according to the above-described embodiment. The program may include only a part of an instruction that calls an appropriate function or module in a controlled manner and obtains a desired result. How the computer system 900 operates is well known and will not be described in detail.

  Further, the present invention is not limited to the above-described embodiment, and various modifications are possible, and it goes without saying that these are also included in the scope of the present invention.

  As described above, according to the attenuation coefficient estimation device and the like according to the present invention, the effect that the attenuation coefficient can be appropriately estimated even when the number of radio wave observation information from the wave source is smaller is obtained. For example, white space is detected. It is useful as a device.

DESCRIPTION OF SYMBOLS 1 Reception apparatus 2 Wave source 3 Attenuation coefficient estimation apparatus 11 Acceptance part 12 Estimation part 13 Storage part 14 Reference information storage part 15 Similarity judgment part 16 Identification part 17 Range estimation part 18 Output part 19 Request information output part 20 High-density observation set acceptance part 21 reference estimation part 22 correct value identification part 23 reference information reception part

Claims (6)

A receiving unit that receives an observation set that is a set of a plurality of observation information having a received signal strength of a radio wave received from a wave source by a receiving device, and a distance and an azimuth angle from the wave source to the receiving device;
A plurality of observations included in the observation set are attenuation coefficients, which are functions related to attenuation characteristics of radio waves from the wave source with respect to a specific azimuth angle, and are coefficients of an attenuation characteristic function that is a function depending on a distance from the wave source. Information and a weight function that decreases as the distance from the specific azimuth decreases, and a weight function that is a function including one or more parameters related to the decrease, and includes an azimuth that is far from the specific azimuth. Estimating with multiple azimuth angles and multiple values of parameters by estimating the regression by regression analysis, which has a smaller effect on the observation information, and using the weight value function of the parameter value and the parameter value. An estimator that obtains correspondence information that associates the attenuation coefficient for each azimuth with respect to a plurality of parameter values;
Azimuth angle of attenuation coefficient for each of a plurality of azimuth angles estimated using a parameter value, a weight function of the parameter value, and a high-density observation set that is a set of observation information larger than the observation set. A plurality of reference correspondence information that associates azimuth characteristics that are characteristics of the direction, and a reference information storage unit that stores a plurality of reference information including correct values that are values of parameters that match the high-density observation set;
A plurality of correspondence information acquired by the estimation unit is used to acquire an azimuth angle characteristic of an attenuation coefficient for each parameter value, and a plurality of azimuth angle characteristics for each acquired parameter value are included in the reference information. A similarity determination unit that determines whether or not the azimuth characteristics for each value of the parameter related to the reference correspondence information are similar by comparing a value indicating the degree of similarity between the two and a predetermined threshold ;
The correctness value of the parameter included in the reference information having the plurality of reference correspondence information determined to be similar to the azimuth angle characteristic for each value of the parameter corresponding to the plurality of correspondence information by the similarity determination unit, according to the correspondence information A specifying unit for specifying an associated attenuation coefficient ,
The value of the parameter suitable for the high-density observation set is the value of the parameter included in the weight function used to estimate the attenuation characteristic function for each azimuth with the smallest error from the plurality of observation information included in the high-density observation set. A damping coefficient estimation device that is a value . Request information for requesting reference information regarding radio waves from the wave source when there is no plurality of reference correspondence information determined by the similarity determination unit to be similar to the azimuth characteristic for each parameter value corresponding to the plurality of correspondence information A request information output unit for outputting
A reference information receiving unit that receives reference information about the radio wave from the wave source in response to the output of the request information by the request information output unit, and stores the reference information in the reference information storage unit;
The attenuation coefficient estimating apparatus according to claim 1, wherein the specifying unit specifies an attenuation coefficient associated with the correct value of the parameter included in the reference information received by the reference information receiving unit by the correspondence information. In response to the output of request information by the request information output unit, a high-density observation set reception unit that receives a high-density observation set related to radio waves from the wave source;
Using a weighting function and the high-density observation set received by the high-density observation set receiving unit, a parameter value and an attenuation coefficient for each of a plurality of azimuth angles estimated using the weight function of the parameter value And a reference estimation unit that obtains a plurality of reference correspondence information by obtaining azimuth characteristics of attenuation coefficients for each of the plurality of azimuths;
A plurality of information obtained by the reference estimation unit and corresponding to a high-density observation set received by the high-density observation set reception unit from a plurality of information that associates parameter values and attenuation coefficients for a plurality of azimuth angles. A correct value specifying unit that specifies an attenuation coefficient for each azimuth angle and specifies a correct value that is a value of a parameter corresponding to the specified attenuation characteristic;
The attenuation coefficient estimation device according to claim 2, wherein the reference information receiving unit receives reference information including reference correspondence information acquired by the reference estimating unit and a correct value specified by the correct value specifying unit. A range estimation unit that estimates a range in which radio waves from the wave source reach using an attenuation characteristic function including an attenuation coefficient identified by the identification unit;
The attenuation coefficient estimation apparatus according to claim 1, further comprising: an output unit that performs an output related to the range estimated by the range estimation unit. A reception step of receiving an observation set which is a set of a plurality of observation information having a received signal intensity of a radio wave received from a wave source by a receiving device, and a distance and an azimuth angle from the wave source to the receiving device;
A plurality of observations included in the observation set are attenuation coefficients, which are functions related to attenuation characteristics of radio waves from the wave source with respect to a specific azimuth angle, and are coefficients of an attenuation characteristic function that is a function depending on a distance from the wave source. Information and a weight function that decreases as the distance from the specific azimuth decreases, and a weight function that is a function including one or more parameters related to the decrease, and includes an azimuth that is far from the specific azimuth. Estimating with multiple azimuth angles and multiple values of parameters by estimating the regression by regression analysis, which has a smaller effect on the observation information, and using the weight value function of the parameter value and the parameter value. An estimation step for acquiring correspondence information for each of the azimuth angles for the values of a plurality of parameters,
Using the plurality of correspondence information acquired in the estimation step, the azimuth characteristic of the attenuation coefficient is acquired for each parameter value, and the parameter value and the parameter are included in the azimuth characteristic for each acquired parameter value. Azimuth angle, which is a characteristic of the attenuation coefficient for each of a plurality of azimuth angles, estimated using a weight function of the value of, and a high-density observation set that is a set of observation information larger than the observation set. Included in the reference information stored in the reference information storage unit that stores a plurality of pieces of reference information including a plurality of pieces of reference correspondence information that associates characteristics with each other, and a correct answer value that is a parameter value that matches the high-density observation set. whether the azimuth angle characteristic for each value of a parameter related to a plurality of reference corresponding information is similar, compared with the predetermined threshold value indicating the degree of both similarity child A similarity determining step of determining by,
In the similarity determination step, the correct value of the parameter included in the reference information having the plurality of reference correspondence information determined to be similar to the azimuth angle characteristic for each value of the parameter corresponding to the plurality of correspondence information is set according to the correspondence information. A specific step of identifying the associated attenuation coefficient ,
The value of the parameter suitable for the high-density observation set is the value of the parameter included in the weight function used to estimate the attenuation characteristic function for each azimuth with the smallest error from the plurality of observation information included in the high-density observation set. A damping coefficient estimation method that is a value . A computer that can access the reference information storage unit,
A receiving unit that receives an observation set that is a set of a plurality of observation information having a received signal strength of a radio wave received by the receiving device from the wave source, and a distance and an azimuth angle from the wave source to the receiving device;
A plurality of observations included in the observation set are attenuation coefficients, which are functions related to attenuation characteristics of radio waves from the wave source with respect to a specific azimuth angle, and are coefficients of an attenuation characteristic function that is a function depending on a distance from the wave source. Information and a weight function that decreases as the distance from the specific azimuth decreases, and a weight function that is a function including one or more parameters related to the decrease, and includes an azimuth that is far from the specific azimuth. Estimating with multiple azimuth angles and multiple values of parameters by estimating the regression by regression analysis, which has a smaller effect on the observation information, and using the weight value function of the parameter value and the parameter value. An estimation unit that obtains correspondence information that associates an attenuation coefficient for each azimuth with respect to a plurality of parameter values,
Using the plurality of correspondence information acquired by the estimation unit, an azimuth angle characteristic of the attenuation coefficient is acquired for each parameter value, and the parameter value and the parameter are set in the azimuth angle characteristic for each acquired parameter value. Azimuth angle, which is a characteristic of the attenuation coefficient for each of a plurality of azimuth angles, estimated using a weight function of the value of, and a high-density observation set that is a set of observation information larger than the observation set. Included in the reference information stored in the reference information storage unit that stores a plurality of pieces of reference information including a plurality of pieces of reference correspondence information that associates characteristics with each other, and a correct answer value that is a parameter value that matches the high-density observation set. on comparing the plurality of whether the azimuth angle characteristic for each value of the parameter relating to reference corresponding information is similar, and a predetermined threshold value indicating the degree of similarity of both Similarity determination unit for determining Te,
The correctness value of the parameter included in the reference information having the plurality of reference correspondence information determined to be similar to the azimuth angle characteristic for each value of the parameter corresponding to the plurality of correspondence information by the similarity determination unit, according to the correspondence information Function as a specific unit for specifying the associated attenuation coefficient ,
The value of the parameter suitable for the high-density observation set is the value of the parameter included in the weight function used to estimate the attenuation characteristic function for each azimuth with the smallest error from the plurality of observation information included in the high-density observation set. A program that is a value .