JP6331072B2 - White space detection device, white space detection method, and program - Google Patents

Description

  The present invention relates to a white space detection device that performs processing related to white space detection.

  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.
As another method for detecting white space, for example, the reach of radio waves due to free space propagation loss can be specified from the position of a pre-registered transmission wave source, and the outside of the range can be set as white space.
For example, a device described in Patent Document 1 is known as a device for detecting an unused frequency spectrum.

Special table 2012-529196 gazette

  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.

  In addition, the method using the position of a transmission wave source with pre-registration has a problem that a white space cannot be detected for a transmission wave source that is not pre-registered. Also, for transmission wave sources that have been pre-registered, the propagation loss of the wave source is assumed to be free space loss, so the reach of radio waves will be estimated wider than necessary, and the detected white space area will be narrower than the actual area. There was also a problem of becoming.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a white space detection device that can detect a white space with a small number of sensors.

In order to achieve the above object, a white space detection device according to the present invention includes a position acquisition unit that acquires a position of a wave source specified by using radio waves from a wave source received by a plurality of first reception devices, The first observation data including the reception power of the radio wave from the wave source observed by the receiving device is received, and a plurality of second data including the reception power of the radio wave from the wave source respectively observed by the plurality of second reception devices. Using the reception unit that receives the observation data, the reception power included in the first observation data, and the distance between the wave source calculated by using the position of the wave source acquired by the position acquisition unit and the first reception device A transmission power estimation unit for estimating the transmission power of the wave source, a transmission power of the wave source estimated by the transmission power estimation unit, a plurality of reception powers included in the plurality of second observation data, and a wave source acquired by the position acquisition unit Calculate using the position of An attenuation characteristic estimator that estimates the attenuation characteristics of radio waves from the wave source using each of the distances between the generated wave source and the plurality of second receiving devices, transmission power of the wave source estimated by the transmission power estimator, and attenuation A white space detection unit that detects the white space by estimating the reach of the radio wave from the wave source using the attenuation characteristic estimated by the characteristic estimation unit, and an output unit that outputs the white space detected by the white space detection unit And.
With such a configuration, by estimating the attenuation characteristics and detecting the white space according to the estimation result, even if the number of receiving devices is smaller than the white space detection method using the conventional spectrum sensing technology, The same level of white space can be detected. Further, since the white space is detected in response to the reception of the radio wave from the wave source by the receiving device, the white space can be detected even for a transmission wave source that has not been pre-registered. In addition, by using the attenuation characteristic estimated by the attenuation characteristic estimation unit instead of using the free space model as the attenuation characteristic from the wave source, it is possible to detect a white space area that is more realistic.

In the white space detection device according to the present invention, the reception unit receives, from the plurality of first reception devices, the first observation data including the reception signal received from the wave source by the first reception device and the reception time of the reception signal. The position acquisition unit respectively receives the reception signals corresponding to the plurality of first reception devices, the reception time points of the reception signals, and the positions of the plurality of first reception devices, and calculates the position of the wave source. May be.
With this configuration, the position of the wave source can be specified by so-called TDoA in the white space detection device.

In the white space detection device according to the present invention, the receiving unit also receives the direction of the wave source acquired by the first receiving device using the radio wave from the wave source from each of the plurality of first receiving devices, and acquires the position. The unit may calculate the position of the wave source using the directions of the wave sources acquired by the plurality of first receiving apparatuses and the positions of the plurality of first receiving apparatuses.
With such a configuration, the position of the wave source can be specified by the so-called DoA in the white space detection device.

In the white space detection device according to the present invention, the reception unit also receives the position of the first reception device from the first reception device, and the transmission power estimation unit is the first reception device received by the reception unit. The transmission power may be estimated using the position.
With such a configuration, for example, even if the first receiving apparatus can move, the transmission power can be estimated using the received position of the first receiving apparatus.

In the white space detection device according to the present invention, the reception unit also receives each position of the second reception device from the plurality of second reception devices, and the attenuation characteristic estimation unit includes the plurality of reception units received by the reception unit. The attenuation characteristic may be estimated using each position of the second receiving device.
With such a configuration, for example, even if the second receiving apparatus can move, the attenuation characteristic can be estimated using the received position of the second receiving apparatus.

In the white space detection device according to the present invention, the attenuation characteristic estimated by the attenuation characteristic estimation unit may depend on the direction from the wave source.
With such a configuration, white space can be detected with higher spatial accuracy.

  In the white space detection device according to the present invention, the number of second reception devices may be larger than the number of first reception devices.

  According to the white space detection apparatus and the like according to the present invention, the attenuation characteristics are estimated, and the white space is detected using the estimated attenuation characteristics. Therefore, it is possible to detect the white space using fewer receiving apparatuses.

The figure which shows the structure of the information communication system containing the white space detection apparatus by Embodiment 1 of this invention. The block diagram which shows the structure of the white space detection apparatus by the embodiment The flowchart which shows operation | movement of the white space detection apparatus by the embodiment The figure which shows an example of the graph of the attenuation | damping characteristic in the same embodiment The figure which shows an example of the use space and white space in the embodiment The figure which shows an example of the graph of the attenuation | damping characteristic in the same embodiment The figure which shows an example of the use space and white space in the embodiment Schematic diagram showing an example of the appearance of a computer system in the present embodiment The figure which shows an example of a structure of the computer system in this Embodiment

  Hereinafter, a white space detection device 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.

(Embodiment 1)
A white space detection apparatus according to Embodiment 1 of the present invention will be described with reference to the drawings. The white space detection device according to the present embodiment detects a white space region by estimating the transmission power of a wave source and estimating the attenuation characteristics of radio waves from the wave source using the estimated transmission power. .

  FIG. 1 is a diagram showing a configuration of an information communication system including a white space detection device 4 according to the present embodiment. In FIG. 1, the information communication system according to the present embodiment includes a plurality of first reception devices 1, a plurality of second reception devices 2, a wave source 3, and a white space detection device 4. The plurality of first reception devices 1 and the plurality of second reception devices 2 and the white space detection device 4 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.

  The first receiving device 1 receives radio waves from the wave source 3. The first receiving device 1 usually acquires the received signal from the wave source 3 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 first reception device 1 may acquire the reception power of the radio wave from the wave source 3. In addition, although it is suitable that the 1st receiver 1 can receive the electromagnetic wave from the wave source 3 by sight, it may not be so. As will be described later, when the position of the first receiving device 1 is also transmitted from the first receiving device 1 to the white space detecting device 4, the first receiving device 1 performs a process of acquiring the position. May be. When the first receiving device 1 is movable, it is preferable that the position of the first receiving device 1 is transmitted to the white space detecting device 4. The number of first receiving apparatuses 1 is not limited. For example, as described later, when position detection by TDoA is performed, the number is preferably three or more, and position detection by DoA is performed. In some cases, the number is preferably 2 or more. In addition, when position detection by DoA is performed, it is preferable that the first receiving device 1 can change the directivity of radio wave reception. The directivity change may be made physically, such as by rotating the directional antenna, or may be made electronically, such as changing the directivity in the phased array antenna. Although FIG. 1 shows a case where the receiving antenna of the first receiving device 1 is a parabolic antenna, it goes without saying that this need not be the case.

  The second receiving device 2 receives radio waves from the wave source 3. The second receiving device 2 usually acquires the received power of the radio wave from the wave source 3 in response to the reception. Note that the second receiving device 2 may not only acquire the received power, but may also acquire a received signal corresponding to the radio wave from the wave source 3, or may not. Further, the second receiving device 2 may not necessarily receive the radio wave from the wave source 3 with a line of sight. That is, the second receiving device 2 may receive the radio wave from the wave source 3 out of line of sight. As will be described later, when the position of the second receiving device 2 is also transmitted from the second receiving device 2 to the white space detecting device 4, the second receiving device 2 performs a process of acquiring the position. May be. When the second receiving device 2 is movable, the position of the second receiving device 2 is preferably transmitted to the white space detecting device 4.

  Note that the number of the second receiving devices 2 may be larger than the number of the first receiving devices 1, but it is not necessary. The number of receiving apparatuses may be, for example, the number per unit area. For example, the first receiving device 1 can receive a radio wave from the wave source 3 with a line of sight, and may be provided for the information communication system according to the present embodiment. In such a case, it is usually difficult to arrange a large number of first receiving apparatuses 1. On the other hand, the second receiving device 2 may receive radio waves from the wave source 3 out of line of sight, and may be a receiving device such as a mobile phone, for example. As such, the second receiving device 2 is usually simpler than the first receiving device 1. Therefore, even if the number of the second receiving devices 2 is larger than the number of the first receiving devices 1, it does not lead to a significant cost increase of the information communication system according to the present embodiment.

  Acquisition of the position in the 1st receiver 1 or the 2nd receiver 2 may be performed using GPS (Global Positioning System), for example, and may be performed using autonomous navigation apparatuses, such as a gyro. It may be performed using a nearby base station such as a mobile phone or a wireless LAN, or may be performed by other methods.

  The wave source 3 may be anything as long as it transmits radio waves. For example, the wave source 3 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. The reachable range of the radio wave from the wave source 3 may be, for example, a range indicated by a dashed ellipse in FIG. In that case, the outside of the broken ellipse becomes a spatial white space for the frequency of the radio wave transmitted by the wave source 3. In the present embodiment, only the case where there is one wave source 3 will be described for simplicity of explanation, but two or more wave sources 3 may exist. In that case, for each wave source 3, there is a radio wave reachable range as indicated by the dashed ellipse in FIG. 1, and the outside of the reachable range is white space. Further, FIG. 1 shows the case where the first receiving device 1 and the second receiving device 2 exist only within the reach of the radio wave from the wave source 3, but the position of the wave source 3 is usually known in advance. Therefore, the first receiving device 1 and the second receiving device 2 exist outside the radio wave reachable range.

  FIG. 2 is a block diagram showing a configuration of the white space detection device 4 according to the present embodiment. In FIG. 2, the white space detection device 4 according to the present embodiment includes a reception unit 41, a position acquisition unit 42, a transmission power estimation unit 43, an attenuation characteristic estimation unit 44, a white space detection unit 45, and an output unit. 46. Note that the white space detection device 4 may have other components. For example, when information is transmitted to the first reception device 1 or the second reception device 2, the white space detection device 4 may include a transmission unit that transmits information.

  The receiving unit 41 receives first observation data from the first receiving device 1. The first observation data includes reception power of radio waves from the wave source observed by the first receiving device 1. The receiving unit 41 may receive a plurality of first observation data from each of the plurality of first reception devices 1 or receive one first observation data from any one of the first reception devices 1. You may receive from. Note that the reception power is included in the first observation data includes, as a result, a situation in which information (for example, a reception signal) that can acquire the reception power is included in the first observation data. For example, when the received signal is IQ signal data, the received power corresponding to the received signal can be known by using the amplitude that is the distance from the origin of the IQ symbol. Therefore, when the received signal is included in the first observation data, it may be considered that the received power is also included in the first observation data. As will be described later, when the position acquisition unit 42 also calculates the position, the reception unit 41 normally receives a plurality of first observation data.

  Further, when position detection by TDoA is performed in the white space detection device 4, the first observation data includes a reception signal received from the wave source 3 by the first reception device 1 and a reception time point of the reception signal. May be included. The received signal and the like are used for calculating the position of the wave source 3 as will be described later. Therefore, when the first observation data includes a reception signal for calculating the position of the wave source 3, the first observation data is transmitted from three or more first reception devices 1, respectively. It is preferred that This is because position detection by TDoA can be performed appropriately. Also, the reception time of the received signal may be the time of reception of the received signal, or may be the time of reception of the received signal indicated with a certain time as a reference. In the latter case, the reception time point may be, for example, a count value of a timer until reception of a reception signal with a certain time point as a reference. In order to appropriately perform position detection by TDoA, information indicating a reception time point, for example, a time, a count value of a timer, and the like are a plurality of first reception devices that transmit first observation data. It is preferred that they are synchronized between one.

  In addition, when position detection by DoA is performed in the white space detection device 4, the reception unit 41 has a plurality of directions of the wave source 3 acquired by the first reception device 1 using radio waves from the wave source 3. You may receive from the 1st receiving device 1, respectively. For example, the receiving unit 41 may receive the direction from two or more first receiving apparatuses 1. In addition, the direction may show the direction of the wave source 3 from the 1st receiver 1, for example. The direction may be indicated by, for example, an azimuth angle centered on the first receiving device 1 (for example, an azimuth angle having north as 0 degrees and east as 90 degrees). Further, the direction of the wave source 3 may be acquired by changing the directivity in the first receiving apparatus 1, for example. Specifically, the direction with the strongest radio wave intensity may be determined as the direction of the wave source.

  The receiving unit 41 may also receive information from which the position of the first receiving device 1 can be acquired from the first receiving device 1. The information from which the position can be acquired may be, for example, the position itself or a first identifier that is an identifier of the first receiving device 1. The information that can acquire the position may be included in the first observation data, for example, or not. When the information whose position can be acquired is the first identifier, in the recording medium (not shown) of the white space detection device 4, the first identifier and the first receiving device 1 identified by the first identifier May be associated with each other. Then, the position corresponding to the first identifier may be acquired in the white space detection device 4.

  In addition, the reception unit 41 receives a plurality of second observation data from the plurality of second reception devices 2, respectively. The second observation data includes reception power of radio waves from the wave source 3 observed by the second receiving device 2. The receiving unit 41 may also receive information from which the position of the second receiving device 2 can be acquired from the second receiving device 2. The information from which the position can be acquired may be, for example, the position itself, or a second identifier that is an identifier of the second receiving device 2. The information from which the position can be acquired may be included in the second observation data, for example, or not. The receiving unit 41 may receive information from which the position can be acquired from each of the plurality of second receiving devices 2. When the information whose position can be acquired is the second identifier, the second identifier and the second receiving device 2 identified by the second identifier in the recording medium (not shown) of the white space detecting device 4 May be associated with each other. Then, the position corresponding to the second identifier may be acquired by the white space detection device 4.

  The first observation data may or may not include a radio wave frequency (sensing frequency) corresponding to the received power included in the first observation data. The same applies to the second observation data. Note that it is preferable that the received power included in the one or more first observation data and the received power included in the plurality of second observation data are the received power of the same frequency. The frequency is usually the frequency of the radio wave from the wave source 3. Further, the first and second observation data may include information other than those described above. For example, as will be described later, the first observation data may include a delay profile generated by the first receiving device 1, a gain and a height of the receiving antenna of the first receiving device 1, and the like. In addition, the first identifier may be transmitted from the first receiving device 1 and received by the receiving unit 41 so that the white space detecting device 4 can acquire the gain and height of the receiving antenna.

  The receiving unit 41 may directly receive the first observation data, the second observation data, and the like from the first receiving device 1 and the second receiving device 2, or via another server or the like. May be received. In the latter case, for example, first observation data from a plurality of first receiving apparatuses 1 and second observation data from a plurality of second receiving apparatuses 2 are collected at a base station or the like. The collected first observation data or the like may be transmitted from the base station or the like to the white space detection device 4. The receiving unit 41 may or may not include a wired or wireless receiving device (for example, a modem or a network card) for receiving. The receiving unit 41 may be realized by hardware, or may be realized by software such as a driver that drives the receiving device.

  The position acquisition unit 42 acquires the position of the wave source 3 specified using radio waves from the wave source 3 received by the plurality of first receiving apparatuses 1. Note that obtaining the position of the wave source 3 may be calculating the position of the wave source 3 or receiving information indicating the position of the wave source 3. In the latter case, for example, the position acquisition unit 42 may receive, for example, the transmitted information indicating the position of the wave source 3, and may read the information indicating the position of the wave source 3 from the recording medium, or Information indicating the position of the wave source 3 may be received via an input device or the like. In the present embodiment, the case where the position acquisition unit 42 calculates the position of the wave source 3 will be mainly described. Here, as a method by which the position acquisition unit 42 calculates the position of the wave source 3, a calculation method by TDoA (Time Difference of Arrival) and a calculation method by DoA (Direction of Arrival) will be described. The position of the wave source 3 may be calculated by other methods. The position may be, for example, latitude and longitude, or a coordinate value based on a certain position. The same applies to other positions.

[Calculation method using TDoA]
In this case, the receiving unit 41 includes a reception signal received from the wave source 3 by the first reception device 1 from each of the three or more first reception devices 1 and a reception time point of the reception signal. Assume that observation data is received. Then, the position acquisition unit 42 uses the reception signals corresponding to the plurality of first reception devices 1 and reception times of the reception signals and the positions of the plurality of first reception devices 1 to determine the position of the wave source 3. Is calculated. The position of the first receiving device 1 is, for example, a position acquired using information that can acquire the position transmitted from the first receiving device 1. Specifically, the position acquisition unit 42 uses the cross-correlation of reception signals received by three or more first receiving apparatuses 1 to transmit the same radio wave transmitted from the wave source 3 to the first receiving apparatus 1. Calculate the time difference reached. The position acquisition unit 42 can calculate the time difference using the reception time point. Further, the position acquisition unit 42 calculates the propagation distance difference from the wave source 3 to the plurality of first receiving devices 1 by multiplying the time difference by the speed of the radio wave (the speed of light). A curve with a constant difference in distance from a certain position is a hyperbola. Therefore, when the difference between the distance from the wave source 3 to the first receiving device 1a and the distance from the wave source 3 to the first receiving device 1b is _Lab , the wave source 3 is connected to the first receiving device 1a. And the position of the first receiver 1b are positioned on a hyperbola having two focal points. Note that the difference between each distance from the point on the hyperbola to the two focal points is _Lab . When the observation data transmitted from the three first receiving apparatuses 1 are used, the position acquisition unit 42 similarly identifies hyperbolic curves for the other two combinations of the first receiving apparatuses 1. The position of the wave source 3 may be calculated by calculating the intersection of the three hyperbolic curves.
For details of the position calculation method by TDoA, 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

[Calculation method by DoA]
In this case, it is assumed that the receiving unit 41 receives the direction of the wave source 3 acquired by the first receiving device 1 from each of the two or more first receiving devices 1. Then, the position acquisition unit 42 calculates the position of the wave source 3 using the direction of the wave source 3 acquired by the plurality of first receiving apparatuses 1 and the respective positions of the plurality of first receiving apparatuses 1. . The position acquisition unit 42 can acquire the position of the first receiving device 1 in the same manner as in the calculation method using TDoA. In addition, when the position of a certain first receiving apparatus 1 and the direction of the wave source 3 therefrom are known, the wave source 3 exists on a straight line that passes through the position and extends in that direction. . Therefore, the position acquisition unit 42 can identify the two straight lines by knowing the positions of the two first receiving apparatuses 1 and the directions of the wave sources 3 from the first receiving apparatuses 1. The position of the wave source 3 that is the intersection of the straight lines can be calculated. In this case, it is preferable that the two first receiving devices 1 and the wave source 3 do not exist on the same straight line.
For details of the position calculation method using DoA, refer to the following document, for example.
Reference: SU Pillai, "Array Signal Processing", Springer-Verlag, 1989

  Further, the position acquisition unit 42 may store the calculated position of the wave source 3 in a recording medium (not shown). Further, when the position acquisition unit 42 does not calculate the position of the wave source 3, the position of the wave source 3 may be calculated by TDoA or DoA as described above by an apparatus other than the white space detection apparatus 4, for example.

  The transmission power estimation unit 43 calculates the reception power included in the first observation data and the distance between the wave source 3 and the first reception device 1 calculated using the position of the wave source 3 acquired by the position acquisition unit 42. And the transmission power of the wave source 3 is estimated. The received power included in the first observation data may be calculated using, for example, a reception signal included in the first observation data. In addition, the transmission power estimation unit 43 uses, for example, the position of the first reception device 1 received by the reception unit 41 or the position associated with the first identifier included in the first observation data. It is possible to acquire the position of the first receiving device 1 that has transmitted the first observation data. Therefore, the transmission power estimation unit 43 uses the position of the first reception device 1 and the position of the wave source 3 acquired by the position acquisition unit 42 to determine the distance between the first reception device 1 and the wave source 3. It can be calculated.

Next, a method for estimating the transmission power of the wave source 3 will be described. First, the relationship between the transmission power and the reception power is as follows. X _i is the propagation distance (km) from the wave source 3 to the i-th first receiving device 1, f is the frequency (MHz) of the radio wave received by the first receiving device 1, and P _{rx, i} is the received power (dBm) in the i-th first receiver 1, P _tx is the transmission power (dBm) of the wave source 3, and G ¹ _{rxant, i} is the i-th first F (x _i , f) is a function (hereinafter referred to as “path loss”) of a propagation loss (path loss) of a radio wave having a propagation distance of x _i and a frequency of f. Called a "propagation loss function").
P _{rx, i} = P _tx + G ¹ _{rxant, i} −F (x _i , f) (1)

In addition, here, a case where the propagation loss function F (x _i , f) is expressed as, for example, the following equation will be described, but this need not be the case. However, a is a distance attenuation coefficient, b is a frequency characteristic coefficient, and c is another coefficient. As will be described later, these coefficients are determined or calculated according to the model to be adopted.
F (x _i , f) = a × Log (x _i ) + b × Log (f) + c
From the above equation (1), the transmission power P _{tx, i} of the wave source 3 calculated using the reception power in the i-th first reception device 1 is as follows.
P _{tx, i} = P _{rx, i} −G ¹ _{rxant, i} + F (x _i , f) (2)

Therefore, the transmission power estimation unit 43 can calculate the transmission power by using the above equation (2). The received power P _{rx, i} is included in the first observation data from the i-th first receiving device 1. G ¹ _{rxant, i} may be included in the first observation data from the i-th first receiving device 1, or the first identifier transmitted from the first receiving device 1 may be May be used. In the latter case, the white space detection device 4 associates the first identifier with the gain G ¹ _{rxant, i} of the reception antenna of the first reception device 1 identified by the first identifier. It may be stored in a recording medium (not shown). Further, the propagation distance x _i, as described above, can be calculated by using the position of the i-th first receiving apparatus 1, the position of the wave source 3 position acquisition unit 42 has acquired. Further, the frequency f may be included in the first observation data, for example, and may be stored in the white space detection device 4. Further, the propagation loss function F is determined according to a model to be adopted, as will be described later. Strictly speaking, the transmission power calculated by the above equation (2) is the antenna power including the influence of the gain of the transmission antenna of the wave source 3. Further, when the reception power of the first reception device 1 is smaller than a predetermined threshold, the reception power may or may not be used for estimation of transmission power.

Here, the coefficients a, b, and c in the case of the free space model, the ground wave two-wave model, and the Okumura-Kashiwa model will be described.
[Free space model]
In the case of a free space model, the coefficients a, b, and c may be set as follows.
a = b = 20
c = 32.44

[Two-wave model of ground reflection]
In the case of a two-wave model of ground reflection, the coefficients a, b, and c may be set as follows.
(1) 1000 For ^{_{× x i <2 1/2 × kh}} b h m a = b = 20
c = 20.4
(2) 1000 × _x ^i> For ^{_{2 1/2 × kh b h m a}} = 40
b = 0
c = 120−20 × Log (h _b h _m )
Here, h _b is the transmitting antenna height (m), and _hm is the receiving antenna height (m). K is a wave number (= 2π / λ = 2πf / c). Here, λ is the wavelength of the radio wave transmitted from the wave source 3, and c is the propagation speed (light speed). Further, in the case of ^{_{1000 × x i = 2 1/2 ×}} kh b h m is the (1) may be either (2).

When this two-wave model of ground reflection is used, it is necessary to obtain the reception antenna height h _m , that is, the height of the antenna of the first reception device 1. The height of the antenna may be included in the first observation data, for example, or, in the white space detection device 4, the first reception and the first reception identified by the first identifier The height of the antenna of the device 1 may be associated with and stored in a recording medium (not shown). Further, since the transmission antenna height h _b , that is, the height of the antenna of the wave source 3 is unknown, a predetermined value (for example, 50 meters or the like) may be used.

[Okumura-Sakai model]
In the case of the Okumura-Kashiwa model, that is, in the case of an urban area model, the coefficients a, b, and c may be set as follows.
a = 44.9−6.55 × Log (h _b )
b = 26.16-1.1 × _h m +1.56
_{c = 69.55-13.82 × Log (h b} ) + 0.7 × h m -0.8
Here, h _b is the transmitting antenna height (m), and _hm is the receiving antenna height (m). Also, this model can be used only when the transmission antenna height h _{b and the} like are in the following range. Note that the reception antenna height and the transmission antenna height may be reversed. That is, h _b may be a receiving antenna height (m), and _hm may be a transmitting antenna height (m).
30 <h _b <200
1 <h _m <10
150 <f <2200
1 <x _i <20

Even when this Okumura-Kashiwa model is used, it is necessary to obtain the receiving antenna height h _m , that is, the height of the antenna of the first receiving device 1. The acquisition method is the same as in the case of the two-wave model of ground reflection. Further, since the transmission antenna height h _b , that is, the height of the antenna of the wave source 3 is unknown, a predetermined value (for example, 50 meters or the like) may be used.

Here, the transmission power estimation unit 43 will briefly describe which of the three models is used to estimate the transmission power. For example, the transmission power estimation unit 43 may set only the free space model from the wave source 3 to each first receiving device 1 and use only the coefficients a, b, and c of the free space model. For example, when each first receiving device 1 is arranged so as to be visible, all of the wave source 3 to the first receiving device 1 can be used as a free space model. On the other hand, the transmission power estimation unit 43 determines whether or not the wave source 3 to the first receiving device 1 is a line of sight using the amount of time variation of the received signal power and the delay profile. A model or a two-wave model of ground reflection may be used, and the Okumura-Sakai model may be used when the line of sight is not visible. A method for determining whether the line of sight is out of sight or not using the delay profile is already known, and detailed description thereof is omitted. The delay profile used in the determination may be generated by the transmission power estimation unit 43 using, for example, the received signal (IQ signal data) included in the first observation data, or is delayed to the first observation data. The profile itself may be included. In the latter case, for example, the first receiving device 1 may generate a delay profile and transmit the delay profile included in the first observation data. Incidentally, in the case not expected, Okumura - if that does not meet the above range h _b such a condition using the Hata model, for example, may be used a different propagation model. In addition, a brief description will be given as to whether to select a free space model or a two-wave model of ground reflection when it is determined that the line of sight is determined using the delay profile. When the receiving antenna height of the first receiving apparatus 1 is sufficiently high and the frequency is high, there is no problem even if the free space model is used because the distance to the break point at which the first Fresnel zone begins to be shielded with the ground is large. Otherwise, the effect of shielding the first Fresnel zone cannot be ignored, so it is preferable to use a two-wave model of ground reflection. Therefore, for example, the transmission power estimation unit 43, when the receiving antenna height of the i-th first receiving device 1 is equal to or higher than the threshold value related to the antenna height and the frequency f is equal to or higher than the threshold value related to the frequency, If this is not the case, a two-wave model of ground reflection may be employed.

Next, the final transmission power, that is, the transmission power P ^p _tx used in the _subsequent- stage attenuation characteristic estimation unit 44 is calculated from the plurality of transmission powers P _{tx, i} calculated using the above equation (2). As a method, a method using a maximum value and a method for performing statistical processing will be described. When the calculation of the position of the wave source 3 is not performed by the white space detection device 4 and the reception unit 41 receives only one first observation data, the calculated transmission power P _tx is calculated. _{, 1} may be used as the transmission power P ^p _tx as it is.

[Method using maximum value]
The transmission power estimation unit 43 may set the maximum value among the calculated transmission powers P _{tx, i} as the final transmission power P ^p _tx . Usually, it is considered that the transmission power calculated using the reception power received through the propagation path which is an ideal line of sight becomes the maximum value. Therefore, it is considered that the transmission power can be set to a more accurate value by setting the maximum value of the transmission power as the transmission power P ^p _tx of the estimation result. Note that a result obtained by adding a positive value margin M to the maximum value may be used as the transmission power P ^p _tx . In this case, the estimated transmission power P ^p _tx is, for example, as follows.
P ^p _tx = max {P _{tx, i} } + M

[How to perform statistical processing]
The transmission power estimation unit 43 may calculate a maximum value of a plurality of transmission powers by performing statistical processing, and use the calculated maximum value as the final transmission power P ^p _tx . Specifically, the transmission power estimation unit 43 calculates the average E and the standard deviation σ of the transmission power {P _{tx, i} } using the calculated transmission powers P _{tx, i} . Then, the transmission power estimation unit 43 may use E + 3σ as the transmission power P ^p _tx . By doing so, the maximum value of the transmission power in consideration of the statistical variation can be set as the transmission power estimation result P ^p _tx .

In the above description, the case where the propagation loss function does not depend on the direction from the wave source 3 has been described, but this need not be the case. The propagation loss function may depend on the direction from the wave source 3. In this case, for example, the distance attenuation coefficient a, the frequency characteristic coefficient b, and the other coefficient c of the propagation loss function are centered on the wave source 3 as a (θ), b (θ), and c (θ), respectively. The angle θ may be dependent on the angle θ. The angle θ may be, for example, an azimuth angle in which the north is 0 degrees and the east is 90 degrees. As such, when the propagation loss function depends on the direction from the wave source 3, the transmission power estimation unit 43 has the angle dependency using the position of the wave source 3 acquired by the position acquisition unit 42, for example. A propagation loss function may be acquired. Specifically, the transmission power estimation unit 43 uses the position of the wave source 3 and the topographic map corresponding to the position stored in a recording medium (not shown) to determine the level of the wave source 3 and the surroundings of the wave source 3. A difference may be specified, and a propagation loss function having angle dependency may be acquired according to the specified result. Further, when the angular dependence of the propagation loss function is measured in advance for each position and the position and the angular dependence corresponding to the position are stored in a recording medium (not shown), the transmission power estimation unit 43 May read out the angular dependence corresponding to the position of the wave source 3 and use a propagation loss function having the angular dependence. The angle dependence stored in advance may be, for example, a coefficient having angle dependence multiplied by the distance attenuation coefficient a, the frequency characteristic coefficient b, and other coefficients c. Specifically, the coefficient having the angle dependency is g _a (θ), g _b (θ), g _c (θ), and a (θ) = a × g _a (θ), b (θ ) = B × g _b (θ), c (θ) = c × g _c (θ). Note that a, b, and c are coefficients acquired or calculated according to each model as described above.

  The attenuation characteristic estimation unit 44 determines the transmission power of the wave source 3 estimated by the transmission power estimation unit 43, the plurality of reception powers included in the plurality of second observation data, and the position of the wave source 3 acquired by the position acquisition unit 42. The attenuation characteristic of the radio wave from the wave source 3 is estimated using the calculated distance between the wave source 3 and the plurality of second receiving apparatuses. Estimating the attenuation characteristic means estimating a propagation loss function. For example, when the propagation loss function is expressed as F above, determining the values of the coefficients a, b, and c may estimate the attenuation characteristics. In addition, when the propagation path from the wave source 3 to the first receiving device 1 becomes a line of sight, as described above, for example, a free space model or the like can be used as the attenuation characteristic. On the other hand, when a communication device is actually used, the operation is often out of sight. Therefore, in the attenuation characteristic estimation unit 44, for example, when the transmission path from the wave source 3 to the second receiving device 2 is out of line of sight, the attenuation is estimated using the received power received by the second receiving device 2. By estimating the characteristics, it is considered that the influence of the wave source 3 in a situation where the communication device is actually operated can be appropriately evaluated, and more accurate white space detection can be realized. Also, it is considered that the more accurate attenuation characteristics can be estimated as the number of second receiving apparatuses 2 increases. As will be described later, when the number of second receiving apparatuses 2 is large, for example, it is possible to estimate the attenuation characteristics depending on the direction from the wave source 3. The attenuation characteristic estimation unit 44 uses, for example, each position of the plurality of second reception devices 2 received by the reception unit 41 or corresponds to each of the second identifiers included in the plurality of second observation data. By using each attached position, it is possible to acquire each position of the plurality of second receiving apparatuses 2 that transmitted the second observation data. Therefore, the transmission power estimation unit 43 uses the position of the second reception device 2 and the position of the wave source 3 acquired by the position acquisition unit 42 to determine the distance between the second reception device 2 and the wave source 3. It can be calculated.

Specifically, the attenuation characteristic estimation unit 44 calculates the attenuation characteristic to be estimated, the transmission power calculated using the reception power in the second receiving device 2, and the transmission power estimated by the transmission power estimation unit 43. The attenuation characteristic may be estimated so that the difference becomes small. That is, the attenuation characteristic estimating unit 44, estimation coefficients as: ^{a p,} b p, may be calculated ^{c p.} The estimation coefficients a ^p , b ^p , and c ^p are estimation results corresponding to the coefficients a, b, and c, respectively. Estimation coefficient a _p, b _p, may be considered a damping characteristic that c _p is estimated, it may be considered a damping characteristic propagation loss function F using these estimation coefficients are estimated. X _j is the propagation distance (km) from the wave source 3 to the j-th second receiving device 2, and P ^p _tx is the transmission power (dBm) of the wave source 3 estimated by the transmission power estimation unit 43. P _{rx, j} is the received power (dBm) at the j-th second receiving device 2, and G ² _{rxant, j} is the gain of the receiving antenna of the j-th second receiving device 2. . Also, F _(x j, f), as described above, a _{F (x j, f) =} a × Log (x j) + b × Log (f) the propagation loss function as a + c, argmin is a , B, c. The sum Σ is the sum from j = 1 to N2, and N2 is the total number of second receiving apparatuses 2 that have transmitted the second observation data used for calculating the attenuation characteristics.
(A ^p , b ^p , c ^p )
_{^{= ArgminΣ j = 1 N2 | P}} p tx -P rx, j + G 2 rxant, j -F (x j, f) | 2 (3)

Therefore, the attenuation characteristic estimation unit 44 can calculate the attenuation characteristic from the position of the wave source 3 by using the above equation (3). The received power P _{rx, j} is included in the second observation data from the j-th second receiving device 2. G ² _{rxant, j} may be included in the second observation data from the j-th second receiving device 2 or may be the second identifier transmitted from the second receiving device 2. May be used. In the latter case, the white space detection device 4 associates the second identifier with the gain G ² _{rxant, j} of the reception antenna of the second reception device 2 identified by the second identifier. It may be stored in a recording medium (not shown). Further, as described above, the propagation distance x _j can be calculated by using the position of the j-th second receiving device 2 and the position of the wave source 3 acquired by the position acquisition unit 42. The frequency f may be included in the second observation data, for example, and may be stored in the white space detection device 4. As described above, the transmission power P ^p _tx included in the above equation (3) is strictly the antenna power including the influence of the gain of the transmission antenna of the wave source 3. Further, when the received power acquired by the second receiving device 2 is smaller than a predetermined threshold value, it may not be used in the above calculation. This is to reduce the influence of noise.

In the above description, the case where the propagation loss function F does not depend on the direction from the wave source 3 has been described, but this need not be the case. F (x _j , f) used in the above equation (3) may depend on the direction from the wave source 3. In that case, for example, the propagation loss function may be expressed by the following equation. Here, θ is an angle with the wave source 3 as the center, and may be an azimuth angle in which the north is 0 degrees and the east is 90 degrees, for example.
F (x, f, θ) = a (θ) × Log (x) + b (θ) × Log (f) + c (θ)

Here, a method for estimating the attenuation characteristic when the propagation loss function depends on θ will be briefly described. When the value of N2, which is the total number of second receiving apparatuses 2, is sufficiently large, the propagation loss function F (x, f, θ) may be calculated for each azimuth angle θ. In this case, if the propagation loss function F (x, f, θ) cannot be calculated for a certain angle θ, the propagation loss at that angle is obtained by interpolating or extrapolating a (θ) or the like. A function may be calculated. On the other hand, when N2 is not so large, the propagation loss function F (x, f, θ) may be calculated for each range of θ. When calculating the propagation loss function for each range of θ, for example, θ may be divided into four ranges every 90 degrees, and the propagation loss function F _n (x, f) may be calculated for each range. . Note that n = 1, 2, 3, 4 and
F _n (x, f) = a _n × Log (x) + b _n × Log (f) + c _n
It may be. The estimation coefficients a _n ^p , b _n ^p , and c _n ^p are the second receiving devices in which the azimuth angle from the wave source 3 is included in the range of 90 degrees × (n−1) ≦ θ <90 degrees × n. It may be calculated using the received power of 2. It should be noted that, except that the estimation coefficients a _n ^p , b _n ^p , and c _n ^p are calculated for each range of 90 degrees × (n−1) ≦ θ <90 degrees × n using the above equation (3), Same as the explanation. In addition, although the case where the range is divided into four ranges every 90 degrees has been described here, the range may be divided into ranges smaller than 90 degrees or may be divided into ranges larger than 90 degrees. Further, the range of the angle to be divided may be equal, such as every 90 degrees, or not. In the latter case, for example, the ranges may be divided so that the number of second receiving apparatuses 2 included in each range is averaged. In the above equation, the distance attenuation coefficient a, the frequency characteristic coefficient b, and the other coefficient c each have an angle dependence, that is, a case where a (θ), b (θ), and c (θ) are obtained. As explained, it doesn't have to be. Only the distance attenuation coefficient a has an angular dependence, and the frequency characteristic coefficient b and the other coefficients c may not have an angular dependence.

The white space detection unit 45 estimates the reach of the radio wave from the wave source 3 using the transmission power P ^p _tx of the wave source 3 estimated by the transmission power estimation unit 43 and the attenuation characteristic estimated by the attenuation characteristic estimation unit 44. To detect white space. The white space is a regional area where radio waves from the wave source 3 do not reach. Specifically, the transmission power ^P _{p tx} wave sources 3 which are estimated, the estimated attenuation characteristic ^{a p,} b p, and ^{c p,} the use of the above (1), away from the wave source 3 by x The antenna power P at the position is expressed by the following equation.
P = P ^p _tx −F ^p (x, f)
However, F ^p (x, f) is a propagation loss function corresponding to the estimated attenuation characteristic, and is represented by the following equation.
F ^p (x, f) = a ^p × Log (x) + b ^p × Log (f) + c ^p

FIG. 4A is a graph showing the relationship between the antenna power and the distance from the wave source 3. In FIG. 4A, when the range in which the power is equal to or higher than the threshold value P ^TH is set as the reach range of the radio wave from the wave source 3, the white space detection device 4 uses P ^p _tx −F ^p (x, f) = P ^TH The range of radio waves can be estimated by calculating the distance x. If the distance is d, d is as follows. However, 10 ^ α means ^10α .
_{^{d = 10 ^ {(P p}} tx -P TH -b p × Log (f) -c p) / a p}
In this case, as shown in FIG. 4B, the range of the circle with the radius d from the wave source 3 becomes the reach range of the radio wave from the wave source 3 and becomes the space used by the wave source 3, and therefore the circle with the radius d The outside is white space.

  In addition, the detection of the white space by the white space detection device 4 may be performed by any method as long as the white space can be distinguished from the other as a result. For example, the white space detection device 4 may acquire information indicating an outline of an area corresponding to the white space, or may acquire information indicating an outline of a use space that is an area that is not a white space. In the latter case, for example, in the case shown in FIG. 4B, the information indicating the outline of the usage space may be information including the position of the wave source 3 and the radius d. Further, when there are a plurality of wave sources 3, there is a use space for each of the wave sources 3, so the white space detection device 4 specifies a white space that is an area not included in any of the use spaces. May be. Further, the white space detection device 4 may detect, for example, a white space indicating a region of the reach of the radio wave from the wave source 3 for a certain frequency, or may detect the white space for each frequency band. Good.

Here, a process for detecting a white space in accordance with an attenuation characteristic having angle dependence will be briefly described. In that case, the reach of the radio wave from the wave source 3 is calculated for each θ. For example, as described above, when a _n ^p , b _n ^p , and c _n ^p corresponding to n = 1 to 4 are estimated, as shown in FIG. 4C, the antenna power is There are four graphs corresponding to each 90 degree range. Then, when the distance at which the power becomes the threshold value P ^TH is calculated for every 90 degrees of the azimuth angle θ, it is assumed that d _{1 to} d ₄ are obtained. Then, for example, as indicated by a solid line in FIG. 4D, the white space detection device 4 may specify a use space whose azimuth angle θ is every 90 degrees, and may set the other region as a white space. Further, the white space detection device 4 may specify the use space so that the boundary line is smoothly connected at θ = 0, 90, 180, and 270 degrees as indicated by the broken line in FIG. 4D.

  The output unit 46 performs output related to the white space detected by the white space detection unit 45. The output may be, for example, adding information indicating the white space to a white space database or the like, or may be other output. For example, it is preferable that a user, a communication device, or the like can distinguish a white space region from a non-white space region by using the output result.

  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. The output unit 46 may or may not include an output device (for example, a display device or a printer). The output unit 46 may be realized by hardware, or may be realized by software such as a driver that drives these devices.

Next, the operation of the white space detection device 4 will be described using the flowchart of FIG.
(Step S101) The white space detection device 4 transmits a transmission request for transmitting the first observation data to the plurality of first reception devices 1. In the transmission request, for example, a frequency may be specified or may not be specified. In the former case, for example, the white space detection device 4 may specify the frequency corresponding to the wave source 3 using the result of spectrum sensing acquired by the first reception device 1. Further, when a frequency is specified in the transmission request, the frequency may be stored in a recording medium (not shown) in the white space detection device 4. This is because it can be used in transmission power estimation and attenuation characteristic estimation. Further, when the frequency is not specified by the transmission request, the first receiving apparatus 1 acquires the received signal with a width of several MHz, for example, and sets the frequency (for example, the center frequency of several MHz width and the range thereof). The first observation data including one or two or more sets of received information and the like may be transmitted.

  (Step S <b> 102) The receiving unit 41 determines whether or not the first observation data is received from each of the plurality of first receiving apparatuses 1. If the first observation data is received from all of the plurality of first receiving apparatuses 1, the process proceeds to step S103, and if not, the process of step S102 is repeated. Note that the first observation data includes information used by the position acquisition unit 42 to acquire the position of the wave source 3.

  (Step S103) The position acquisition unit 42 calculates the position of the wave source 3 using information included in the plurality of first observation data received by the reception unit 41. The calculated position of the wave source 3 may be stored in a recording medium (not shown).

  (Step S <b> 104) The transmission power estimation unit 43 uses the position of the wave source 3 calculated in step S <b> 103 and the positions of the plurality of first receiving apparatuses 1 to use the wave source 3 and the plurality of first receiving apparatuses 1. And the respective distances are calculated. Then, the transmission power estimation unit 43 estimates the transmission power of the wave source 3 using each distance and the reception power included in the first observation data. The estimated transmission power may be stored in a recording medium (not shown).

  (Step S105) The white space detection device 4 transmits a transmission request for transmitting the second observation data to the plurality of second reception devices 2. Also in the transmission request, the frequency may be specified or not as in step S101. In the latter case, for example, the second receiving device 2 acquires received power with a width of several MHz, and receives second observation data including one or more sets of the frequency and the received power. You may send it.

  (Step S <b> 106) The receiving unit 41 determines whether the second observation data is received from each of the plurality of second receiving apparatuses 2. When the second observation data is received from all the second receiving apparatuses 2 or from a number of second receiving apparatuses 2 equal to or greater than a predetermined threshold value, the process proceeds to step S107. Repeats the process of step S106.

  (Step S107) The attenuation characteristic estimation unit 44 uses the position of the wave source 3 calculated in step S103 and the positions of the plurality of second reception devices 2 to use the wave source 3 and the plurality of second reception devices 2. And the respective distances are calculated. And the attenuation characteristic estimation part 44 estimates an attenuation characteristic using each distance, the transmission power estimated by step S104, and the reception power contained in 2nd observation data. The estimated attenuation characteristic may be stored in a recording medium (not shown).

  (Step S108) The white space detection unit 45 detects the white space using the transmission power estimated in step S104 and the attenuation characteristic estimated in step S107.

  (Step S109) The output unit 46 performs output related to the white space detected in step S108. Then, a series of processing for detecting the white space ends.

  Note that the order of processing in the flowchart of FIG. 3 is an example, and the order of each step may be changed as long as similar results can be obtained. For example, transmission requests to the first and second receiving apparatuses 1 and 2 are simultaneously made, and the first and second observation data are received accordingly. After the reception, the processes of steps S103, S104, S107 and the like are performed. You may go. Moreover, although this flowchart demonstrated the case where the 1st and 2nd receivers 1 and 2 transmitted 1st and 2nd observation data according to a transmission request, it does not need to be so. The first and second receiving apparatuses 1 and 2 may transmit the first and second observation data regardless of the transmission request. In that case, for example, the first and second receiving apparatuses 1 and 2 may transmit the first and second observation data at predetermined times. Further, when the first and second observation data are transmitted in response to the transmission request and the frequency is specified by the transmission request, the first and second receiving apparatuses 1 and 2 When the received power of the designated frequency is not equal to or higher than a predetermined threshold, the first and second observation data may not be transmitted. When a plurality of sets of frequencies and received signals and received powers are transmitted from the first and second receiving apparatuses 1 and 2, the white space detecting apparatus 4 estimates transmission power for each frequency. The white space may be detected for each frequency.

  As described above, according to the white space detection device 4 according to the present embodiment, the position of the wave source 3, the estimated transmission power of the wave source 3, and the estimated attenuation characteristics of the radio wave from the wave source 3 are used. White space can be detected. Therefore, the white space can be detected even when the number of receiving apparatuses is smaller than that in the case of detecting the white space using the conventional spectrum sensing technology. In addition, since the attenuation characteristic is calculated using the received power acquired by the second receiving apparatus 2 instead of using a free space model, it is possible to estimate the attenuation characteristic in accordance with the actual situation, and more accurate white The space area can be detected. In addition, when estimating the attenuation characteristic depending on the direction from the wave source 3, a more accurate attenuation characteristic is calculated, and as a result, the white space can be detected with high accuracy.

  In the present embodiment, the case where the first and second receiving apparatuses 1 and 2 are different types of receiving apparatuses has been mainly described, but this need not be the case. The first and second receiving apparatuses 1 and 2 are the same type of receiving apparatus. Among them, the receiving apparatus used for the process of acquiring the position and estimating the transmission power is called the first receiving apparatus 1 and is attenuated. It may be considered that the receiving device used for the characteristic estimation process is called the second receiving device 2.

  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 component 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 in 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 white space detection device 4 have communication devices, input devices, or the like, the two or more components have a physically single device. Or may have separate devices.

  In the above 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 white space detection apparatus 4 in the said embodiment is the following programs. That is, this program causes a computer to acquire a position of a wave source specified by using radio waves from wave sources received by a plurality of first receiving devices, from a wave source observed by the first receiving device. A first receiving unit that receives first observation data including received power of a plurality of radio waves and receives a plurality of second observation data including received power of radio waves from a wave source respectively observed by a plurality of second receiving devices; Transmission for estimating the transmission power of the wave source using the reception power included in the first observation data and the distance between the wave source calculated by using the position of the wave source acquired by the position acquisition unit and the first reception device A power estimation unit, a transmission power of the wave source estimated by the transmission power estimation unit, a plurality of reception powers included in the plurality of second observation data, and a wave source calculated using the position of the wave source acquired by the position acquisition unit; Multiple second receivers An attenuation characteristic estimation unit that estimates an attenuation characteristic of a radio wave from the wave source using each distance to the device, a transmission power of the wave source estimated by the transmission power estimation unit, and an attenuation characteristic estimated by the attenuation characteristic estimation unit; Is a program for functioning as a white space detection unit that detects the white space by estimating the reach of the radio wave from the wave source, and an output unit that outputs the white space detected by the white space detection unit.

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

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. 5 is a schematic diagram showing an example of the external appearance of a computer that executes the program and realizes the white space detection device 4 according to the embodiment. The above-described embodiment can be realized by computer hardware and a computer program executed on the computer hardware.
In FIG. 5, 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. 6 is a diagram showing an internal configuration of the computer system 900. In FIG. 6, 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 functions of the white space detection device 4 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 functions of the white space detection device 4 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 white space detection device and the like according to the present invention, it is possible to detect the white space using a smaller number of receiving devices, which is useful as a device for constructing a white space database, for example. is there.

DESCRIPTION OF SYMBOLS 1 1st receiver 2 Second receiver 3 Wave source 4 White space detector 41 Receiver 42 Position acquisition part 43 Transmission power estimation part 44 Attenuation characteristic estimation part 45 White space detection part 46 Output part

Claims (9)

A position acquisition unit that acquires the position of the wave source specified by using radio waves from the wave source received by the plurality of first receiving devices;
The first observation data including the reception power of the radio wave from the wave source observed by the first reception device is received, and the reception power of the radio wave from the wave source observed by each of the plurality of second reception devices is received. A receiving unit for receiving a plurality of second observation data including:
Using the received power included in the first observation data, and the distance between the wave source calculated by using the position of the wave source acquired by the position acquisition unit and the first receiving device, the wave source A transmission power estimation unit that estimates transmission power;
Calculated using the transmission power of the wave source estimated by the transmission power estimation unit, the plurality of reception powers included in the plurality of second observation data, and the position of the wave source acquired by the position acquisition unit An attenuation characteristic estimation unit that estimates an attenuation characteristic of a radio wave from the wave source using each distance between the wave source and the plurality of second receiving devices;
White space detection for detecting white space by estimating the reach of radio waves from the wave source using the transmission power of the wave source estimated by the transmission power estimation unit and the attenuation characteristic estimated by the attenuation characteristic estimation unit And
An output unit that performs output related to the white space detected by the white space detection unit. The receiving unit receives, from each of the plurality of first receiving devices, first observation data including a reception signal received from the wave source by the first receiving device and a reception time point of the received signal,
The position acquisition unit calculates a position of the wave source using a reception signal corresponding to the plurality of first reception devices, a reception time point of the reception signal, and each position of the plurality of first reception devices. The white space detection device according to claim 1. The receiving unit also receives the direction of the wave source acquired by the first receiving device using radio waves from the wave source from the plurality of first receiving devices, respectively.
The position acquisition unit calculates a position of the wave source using a direction of the wave source acquired by the plurality of first receiving apparatuses and each position of the plurality of first receiving apparatuses. The white space detection device according to 1. The receiving unit also receives the position of the first receiving device from the first receiving device;
4. The white space detection device according to claim 1, wherein the transmission power estimation unit estimates the transmission power using a position of the first reception device received by the reception unit. 5. The receiving unit also receives each position of the second receiving device from the plurality of second receiving devices,
5. The white space detection according to claim 1, wherein the attenuation characteristic estimation unit estimates the attenuation characteristic using each position of the plurality of second reception devices received by the reception unit. apparatus. The white space detection device according to any one of claims 1 to 5, wherein the attenuation characteristic estimated by the attenuation characteristic estimation unit depends on a direction from the wave source. 7. The white space detection device according to claim 1, wherein the number of the second reception devices is larger than the number of the first reception devices. A position acquisition step of acquiring the position of the wave source identified by using radio waves from the wave source received by the plurality of first receiving devices;
Receiving first observation data including received power of radio waves from the wave source observed by the first receiving device;
Receiving a plurality of second observation data including received power of radio waves from the wave source respectively observed by a plurality of second receiving devices;
Using the received power included in the first observation data and the distance between the wave source calculated using the position of the wave source acquired in the position acquisition step and the first receiving device, A transmission power estimation step for estimating transmission power;
Calculated using the transmission power of the wave source estimated in the transmission power estimation step, the plurality of reception powers included in the plurality of second observation data, and the position of the wave source acquired in the position acquisition step An attenuation characteristic estimating step for estimating an attenuation characteristic of a radio wave from the wave source using each distance between the wave source and the plurality of second receiving devices;
White space detection for detecting white space by estimating the reach of radio waves from the wave source using the transmission power of the wave source estimated in the transmission power estimation step and the attenuation characteristic estimated in the attenuation characteristic estimation step Steps,
An output step for performing an output relating to the white space detected in the white space detection step. Computer
A position acquisition unit that acquires the position of the wave source specified by using radio waves from the wave source received by the plurality of first receiving devices;
The first observation data including the reception power of the radio wave from the wave source observed by the first reception device is received, and the reception power of the radio wave from the wave source observed by each of the plurality of second reception devices is received. A receiving unit for receiving a plurality of second observation data including:
Using the received power included in the first observation data, and the distance between the wave source calculated by using the position of the wave source acquired by the position acquisition unit and the first receiving device, the wave source A transmission power estimation unit for estimating transmission power;
Calculated using the transmission power of the wave source estimated by the transmission power estimation unit, the plurality of reception powers included in the plurality of second observation data, and the position of the wave source acquired by the position acquisition unit An attenuation characteristic estimation unit that estimates an attenuation characteristic of a radio wave from the wave source using each distance between the wave source and the plurality of second receiving devices;
White space detection for detecting white space by estimating the reach of radio waves from the wave source using the transmission power of the wave source estimated by the transmission power estimation unit and the attenuation characteristic estimated by the attenuation characteristic estimation unit Part,
The program for functioning as an output part which performs the output regarding the white space which the said white space detection part detected.

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