JP4977077B2 - Signal source position estimation method - Google Patents

Description

  The present invention relates to a signal source position estimation method using a multi-beam antenna.

  Conventionally, a method for estimating an arrival direction of an interference wave using a unitary directional beam is known. FIG. 18 is a diagram illustrating a conventional method for estimating the arrival direction of an interference wave. As shown in FIG. 18, conventionally, a unitary directional beam is physically scanned in a horizontal direction and a vertical method to estimate the arrival direction of an interference wave.

  Further, for example, Japanese Patent Application Laid-Open No. 11-266228 (Patent Document 1) discloses a multi-beam antenna system. In this multi-beam antenna system, in a CDMA radio base station, signals received by a plurality of antenna elements of a receiving-side array antenna are subjected to beam forming by a reception beam former RBF to electrically form a plurality of uplink beams. Then, reception is performed based on an optimum beam (for example, a beam having the maximum power) among the plurality of uplink beams. In addition, a transmission beam former TBF that performs beam forming on the transmission signal is provided, and the control unit CNT performs downlink beam forming based on the presence or absence of the uplink reception signal to form a downlink transmission beam in the same direction as the uplink reception beam, Alternatively, it is controlled whether or not downlink beamforming is performed.

  As a method of estimating a propagation path, a method of estimating the state of the propagation path by observing a reception spectrum characteristic in a single wideband signal is known.

Japanese Patent Laying-Open No. 2000-040987 (Patent Document 2) discloses a wireless communication system. In this radio communication system, channel characteristics are estimated by an automatic equalizer provided in the base station apparatus, and based on the estimation result, the inverse characteristics of the channel are added to the downlink transmission data transmitted to the terminal apparatus. The data to which the reverse characteristic of the propagation path is added is transmitted as transmission data to the terminal device.
JP-A-11-266228 JP 2000-040987 A

  However, in the method shown in FIG. 18, it takes a long time to scan the beam for estimating the position (direction of arrival) of the signal source (desired wave or interference wave), and the apparatus becomes large. In addition, in the estimation of the propagation path, only the observation of the reception spectrum of a single wideband signal does not reveal a remarkable feature related to the propagation path situation, so that it is not easy to estimate the sufficient propagation path situation.

  The present invention has been made in view of such circumstances, and a signal source position estimation method capable of specifying the position of a signal source or an interference source by using a multi-beam antenna in ground mobile communication using radio. The purpose is to provide.

  (1) In order to achieve the above object, the present invention has taken the following measures. That is, the signal source position estimation method of the present invention is a signal source position estimation method by a position estimation station equipped with a multi-beam antenna capable of beam forming in the horizontal direction and the vertical direction by electronic control. Performing beam forming in the horizontal direction to detect a difference in antenna gain between a pair of adjacent beams for each set of beams, performing fast Fourier transform on the received signal, and performing channel estimation; An inverse fast Fourier transform is performed on the signal after channel estimation to calculate an impulse response, a step of obtaining a relative delay time between a plurality of paths indicated in the impulse response, and an impulse response. For each path, the antenna gain of each beam pair acquired in advance A step of estimating an azimuth corresponding to a difference in antenna gain of the detected beam set with reference to data in which the difference and the azimuth are associated one-to-one, topographic information, and the position and shape of the building Map information including at least building information indicating the location of the location estimation station, and the arrival position corresponding to each path on the map based on the azimuth angle and radio wave transmission speed of at least two paths with reference to the position of the position estimation station. Drawing at least a predicted route line in order of increasing relative delay time; and determining a position on the map where the predicted route lines of all the paths intersect at the same time. It is said.

  In this way, on the map based on the estimated azimuth angle and the relative delay time between the paths, the positions where the predicted arrival route lines of all the paths intersect at the same time are determined. The direction of the signal source can be estimated with high accuracy. Further, since the beam forming can be performed in the horizontal direction and the vertical direction by electronic control, it is possible to instantaneously switch from the antenna pattern beam-formed in the horizontal direction to the antenna pattern beam-formed in the vertical direction. As a result, unlike the prior art, it is not necessary to scan the beam for detecting the direction of arrival of the signal source, and the position of the signal source can be estimated in a short time. Further, it is possible to promote interference avoidance and effective use of frequency. Further, the use of the software defined radio makes it possible to implement the present invention without greatly changing the conventional hardware.

  (2) The signal source position estimation method of the present invention is a signal source position estimation method by a position estimation station having a multi-beam antenna capable of beam forming in the horizontal direction and the vertical direction by electronic control, Performing beam forming in the horizontal direction and vertical direction with a beam antenna, detecting a difference in antenna gain between a pair of adjacent beams for each set of beams, performing fast Fourier transform on the received signal, Performing estimation, performing inverse fast Fourier transform on the signal after channel estimation, calculating an impulse response, obtaining a relative delay time between a plurality of paths indicated in the impulse response, For each path indicated in the impulse response, for each beam acquired in advance. A step of estimating an azimuth angle and an elevation angle corresponding to the difference in antenna gain of the detected set of beams with reference to data in which a difference in antenna gain and an azimuth angle are in a one-to-one correspondence; Map information including building information indicating at least the position and shape of the building, and on the map based on the azimuth angle or elevation angle of at least two paths and the transmission speed of radio waves with reference to the position of the position estimation station. Drawing the predicted arrival route lines corresponding to the paths in the order of the relative delay time, and determining a position on the map where the predicted arrival route lines of all the paths intersect at the same time. And at least.

  In this way, the position where the predicted arrival route lines of all paths intersect at the same time is determined on the map based on the estimated azimuth angle, elevation angle, and relative delay time between the paths. However, the direction of the signal source can be estimated with high accuracy. In addition, since the elevation angle can be taken into consideration, it is possible to specify the position of the signal source using a ground reflection path in the line of sight. Further, since the beam forming can be performed in the horizontal direction and the vertical direction by electronic control, it is possible to instantaneously switch from the antenna pattern beam-formed in the horizontal direction to the antenna pattern beam-formed in the vertical direction. As a result, unlike the prior art, it is not necessary to scan the beam for detecting the direction of arrival of the signal source, and the position of the signal source can be estimated in a short time. Further, it is possible to promote interference avoidance and effective use of frequency. Further, the use of the software defined radio makes it possible to implement the present invention without greatly changing the conventional hardware.

  (3) Further, in the signal source position estimation method of the present invention, the distance between the head positions indicating the distance between the head positions of each arrival prediction route line is calculated, and the time when the distance between the head positions is the minimum is obtained. The method further includes a step of identifying a region including all positions on each arrival prediction route line in time.

  As described above, the time at which the distance between the head positions is minimum is obtained, and the region including all the positions on each arrival prediction route line at this time is specified, so that the position estimation error can be corrected. In other words, errors may occur when estimating angles, drawing on maps, and calculating impulse responses, etc. Even if such errors exist, by performing correction to identify a certain area, It is possible to estimate the position of the signal source.

  (4) In the signal source position estimation method of the present invention, when the arrival prediction route line collides with an obstacle on the map, drawing is performed based on the principle of radio wave reflection and diffraction. Yes.

  Thus, since drawing is performed based on the principle of radio wave reflection and diffraction, more accurate drawing can be performed. For example, by using the ray tracing method, reflection and diffraction of radio waves can be expressed on a map.

  According to the present invention, the position where the predicted arrival route lines of all the paths intersect at the same time is determined on the map based on the estimated azimuth angle and the relative delay time between the paths. However, the direction of the signal source can be estimated with high accuracy. Further, since the beam forming can be performed in the horizontal direction and the vertical direction by electronic control, it is possible to instantaneously switch from the antenna pattern beam-formed in the horizontal direction to the antenna pattern beam-formed in the vertical direction. As a result, unlike the prior art, it is not necessary to scan the beam for detecting the direction of arrival of the signal source, and the position of the signal source can be estimated in a short time. Further, it is possible to promote interference avoidance and effective use of frequency. Further, the use of the software defined radio makes it possible to implement the present invention without greatly changing the conventional hardware.

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram illustrating a schematic configuration of a wireless communication system according to the present embodiment. In Figure 1, the radio base station 100 is provided with the receiving-side array antenna ANT _1, the array antenna ANT ₁ has a plurality of antenna elements _AR 1 to Ar _N. The radio base station 100 is provided with an array antenna ANT ₂ on the transmission side, the array antenna ANT ₂ has a plurality of antenna elements _AT 1 to AT _N.

The reception circuits RV _{1 to} RV _N perform high frequency amplification, frequency conversion, and the like of the reception signal. Transmitting circuit _SD 1 to SD _N is frequency conversion, performs high-frequency amplification. The reception beam former RBF performs reception beam forming on the signals received by the _N antenna elements AR _{1 to} ARN to electrically form _M uplink reception beams B _{1 to} B _M. The transmission beamformer TBF can generate a transmission beam having directivity in a predetermined direction by performing transmission beamforming on a transmission signal to generate an antenna element input signal and inputting the input signal to each antenna element. .

  The control unit CNT controls the reception beam former RBF and the transmission beam former TBF to generate a desired beam. The receiving unit RV performs signal detection and error correction, and the transmitting unit SD modulates transmission data. The power monitor PWM observes the received power in an arbitrary beam and is used for estimating the signal source arrival angle. The spectrum monitor SPM observes a signal spectrum received in an arbitrary beam and is used for estimating a transmission path condition. FIG. 1 shows both transmission and reception configurations, but only the reception function is used when estimating the position of the signal source.

  FIG. 2 is a diagram showing the basic concept of the signal source position estimation method of the present invention with respect to the horizontal direction (azimuth angle direction). In the present invention, a difference in received power between two adjacent beams is detected, and a signal source arrival angle is obtained from the difference (= antenna gain difference). That is, in the position estimation station (hereinafter, simply referred to as “estimation station”), the gain difference between adjacent beams is calculated in advance, and the arrival angle is calculated from the difference between the two detected powers. For example, as shown in FIG. 2, the difference between the received power (antenna gain) of the beam 4 and the received power (antenna gain) of the beam 5 is obtained and acquired in advance as shown on the right side in FIG. The azimuth angle corresponding to the difference between the detected antenna gains of the beams 4 and 5 is estimated with reference to the data in which the difference between the antenna gains and the azimuth angles of the sets of beams is one-to-one. The same applies to the vertical direction (elevation direction).

  FIG. 3A shows an example of multi-beam antenna gain characteristics when beam forming is performed in the horizontal direction, which is used when obtaining the signal source arrival angle in the horizontal direction. FIG. 3B shows a vertical beam. FIG. 4 shows multi-beam antenna gain characteristics when beam forming is performed in the vertical direction, which is used when obtaining the signal source arrival angle in the vertical direction. The horizontal direction and the vertical direction in FIG. 3 are interchanged, and four beams in a low elevation angle direction as viewed from the antenna are used.

  In the signal source position estimation method according to the present invention, the position estimation station using these multi-beam antenna systems estimates the signal source position by estimating the horizontal and vertical signal source arrival angles.

  Next, the procedure of the signal source position estimation method of the present invention will be described. In the multi-beam antenna of the position estimation station shown in FIG. 5 (a), horizontal beam forming shown in FIG. 3 (a) is performed. In this state, the received power difference between the beam having the maximum received power of the signal source and the beam having the higher received power among the adjacent beams is obtained. The azimuth angle is calculated from the relationship between the gain difference between the two beams calculated in advance and the azimuth angle to obtain an estimated value of the horizontal signal source arrival angle.

  In the multi-beam antenna of the position estimation station shown in FIG. 5B, vertical beam forming shown in FIG. 4 is performed. In this state, the received power difference between the beam having the maximum received power of the signal source and the beam having the higher received power among the adjacent beams is obtained. The elevation angle is calculated from the previously calculated relationship between the gain difference between the two beams and the elevation angle, and is used as an estimated value of the signal source arrival angle in the vertical direction.

  The position of the signal source is estimated from the estimated values of the signal source arrival angles in the horizontal and vertical directions. When the height of the signal source is unknown, only the direction of the signal source can be estimated. However, when the height of the signal source is known, the position of the signal source can be estimated.

  When position estimation is performed using a multi-beam antenna, a signal propagated in multiple paths cannot be divided for each propagation path as it is. In this case, position estimation must be performed from all of the multiple components. As a result, a signal passing through a propagation path with small propagation attenuation, that is, a signal component having a large received power becomes dominant, and the error becomes large.

  In cognitive radio, it is necessary to measure the surrounding radio environment and perform optimal control of the radio system and antenna. One of the basic characteristics of the wireless environment is the propagation path condition, which requires easy measurement without the addition of special hardware (measuring instruments, antennas, etc.). Yes. For the environmental control as described above, it is necessary to obtain the estimated value in the receiver in real time.

  The present embodiment realizes the following method in order to meet such a demand. First, the transfer function of the propagation path and the impulse response derived from the transfer function will be described. FIG. 6 is a diagram illustrating a schematic configuration of a propagation state monitoring apparatus having a function of obtaining a transfer function from a received signal. For example, in an OFDM communication system such as WiMAX, the RF unit 60 obtains a received wave (received signal), performs analog / digital conversion in the A / D conversion unit 61, and then performs multicarrier demodulation in the FFT circuit 62. Do. Thereafter, the channel estimation unit 63 performs channel estimation in order to compensate for the multipath distorted signal. Then, channel equalization unit 64 performs channel equalization, and decoding unit 65 performs decoding. Channel estimation is performed by using a preamble signal added on the transmission side and comparing it with a known signal held on the receiver side. The propagation state monitoring device 50 outputs the amplitude and phase obtained by the channel estimation unit 63. In FIG. 6, the amplitude and phase are configured to be displayed on a PC.

  FIG. 7 is a diagram illustrating a test configuration example of the propagation state monitoring apparatus. In order to simulate multipath propagation, an equivalent baseband signal is created as waveform data and input to an SG (signal generator) to obtain an RF signal. FIG. 8 is a diagram showing the amplitude and phase of the multipath propagation model. An example of the spectrum (transfer function) of the amplitude and phase of each subchannel obtained by the propagation state monitoring apparatus shown in FIG. 6 is shown in the upper left and lower left of FIG. In addition, examples of the amplitude and phase spectrum (transfer function) of each subchannel calculated from the parameters set in SG shown in FIG. 7 are shown in the upper right and lower right of FIG. As shown in FIG. 8, the amplitude and phase spectrum of each subchannel obtained by the propagation state monitoring apparatus (FIG. 6), and the amplitude and phase spectrum of each subchannel calculated from the parameters set in SG (FIG. 7). ) Is in good agreement.

  FIG. 9 is a diagram illustrating a characteristic (impulse response) obtained by inverse Fourier transform of the transfer function measured by the propagation state monitoring apparatus. This impulse response has a meaning as a delay profile of the propagation path. In FIG. 9, the peak (extreme value) uttered according to the delay time represents each delay component in the multipath. In this way, by performing inverse Fourier transform on the transfer function, it is possible to divide the multiple propagated signal for each delay component. FIG. 10 is a diagram illustrating an example of an impulse response when paths 1 to 3 are obtained. As shown in FIG. 10, it is possible to select an impulse having a large received power when it has a time difference equal to or greater than the resolution of the time axis of the impulse response. Then, an impulse having a large received power is selected, and a relative delay time (relative delay time) of each path is calculated.

(Example of signal source position estimation)
FIG. 11 is a diagram showing how the direction of arrival of a path to be written is specified from the difference in received power of beams using the radio wave arrival direction estimation method as described above. An arbitrary reference line is determined, and an angle of the arrival direction of each path is measured from the reference line. Specifically, it determines which impulse response each path corresponds to while turning on / off the multi-beam antenna.

  FIGS. 12A and 12B are diagrams illustrating an operation for associating the arrival direction of the path with the impulse response. As shown in FIG. 12A, when only the second beam from the right is turned ON and the reception level of the impulse response path 1 shown in FIG. 12B is higher than when other beams are turned ON, It is determined that the path C shown in FIG. 12A corresponds to the path 1 shown in FIG.

  FIG. 13 is a diagram showing an operation for associating the arrival direction of the path with the impulse response. As shown in FIG. 13A, when only the third beam from the right is turned ON, and the reception level of the impulse response path 2 shown in FIG. 13B is higher than when other beams are turned ON, It is determined that the path B shown in FIG. 13A corresponds to the path 2 shown in FIG. FIG. 14 is a diagram illustrating an operation for associating the arrival direction of a path with an impulse response. As shown in FIG. 14A, when only the fourth beam from the right is turned ON, and the reception level of the impulse response path 3 shown in FIG. 14B is higher than when other beams are turned ON, It is determined that the path A shown in FIG. 14A corresponds to the path 3 shown in FIG. The correspondence relationships of the paths obtained as described above are summarized as position estimation parameters as shown in the following table.

FIG. 15 is a diagram illustrating an example of a signal source position estimation method according to the present embodiment. Once the parameters shown in the table above are obtained, they are developed on a map and the position of the signal source is estimated. Here, for example, a propagation characteristic simulation technique by ray tracing can be used. The map information uses terrain data and detailed building data (for example, building shape and height data).

FIG. 16 is a flowchart showing a procedure for estimating the position of a signal source using map information. First, the local station position (position estimation station position) is detected using GPS or the like, and the local station position is plotted on a map (step S1). Next, an expected arrival route line is drawn from the position of the own station in the direction of arrival angle in the above table at a radio wave transmission speed (3.0 × 10 ⁸ m / s) (step S2). The predicted arrival route line of each path starts from the path with the latest arrival time, and draws the next path after the relative delay time. Here, for example, lines are drawn in the order of pass 3, pass 2, and pass 1. Here, when the predicted arrival route line hits an obstacle such as a building on the map, the predicted arrival route line is drawn by reflecting and diffracting using the ray tracing technique (step S3). It is determined (estimated) that the place where the expected arrival route lines of all paths intersect at the same time is the signal source (step S4).

  FIG. 17 is a diagram illustrating an example of a correction method according to the present embodiment. In other words, errors may occur during angle estimation, map drawing, and impulse response calculation. For this reason, correction is performed in consideration of the existence of errors within a certain range. As shown in FIG. 17, in order to correct the estimated position of the signal source, first, the distance between the leading points of the predicted lines of each path is obtained. Then, the time at which the distance between the head points is minimized is obtained, and it is predicted that the interfering station is within the area surrounded by the head points of the paths plotted at this time. As a result, even if there is an error, it is possible to estimate the position of the signal source by performing correction for specifying a certain region. As another estimated position correction example, there is a method of performing simulation by adding an error of about plus or minus 10 degrees to θ1, 2, 3 so that the intersection of each path arbitrarily matches the time.

  In the above description, an example using three paths is shown, but the present invention is not limited to this, and the position of the signal source can be estimated using at least two paths. is there. As a result, the position of the signal source can be estimated in a radio environment that is out of sight. On the other hand, even in a line-of-sight wireless environment, a plurality of paths can be obtained by considering ground reflection. This is because in this embodiment, not only the direction angle of the radio wave but also the elevation angle can be measured. When three-dimensional information such as the height of a building is obtained on a map, this embodiment is applied. For example, by drawing on a cross-sectional view cut in the height direction, the signal source The position can be estimated.

  Further, even when only one path can be recognized in a line-of-sight wireless environment, the position of the signal source can be specified by taking the received power into consideration. In this case, the relationship between the received power value and the distance is stored in advance as a table, the arrival direction of one path is specified, and the received power is measured to obtain the distance to the signal source. And it becomes possible to pinpoint the position of a signal source by using map information.

  Furthermore, in the above description, the case where the signal source is stopped (in the case where the signal source is fixed) is shown as an example, but the present invention can be applied even when the signal source is moving. It is. This is because the instantaneous position can be obtained even when the signal source is moving.

  As described above, in the conventional signal source position estimation method, only the arrival angle direction of the radio wave from the signal source viewed from the receiver can be known. In the present embodiment, since map information is used, reflection / diffraction can be taken into consideration, and position estimation accuracy can be improved. Note that the present invention makes it easy to place multiple base stations by grasping the position of existing base stations that can be sources of interference when, for example, disasters, etc., when it is desired to place base stations without performing station placement design in advance. It can be expected to be used as a means to perform In addition, the signal source position estimation method according to the present invention can be applied to an entrance line to a base station when a mobile phone has been converted to IP, a link between base stations of a cognitive radio system, and the like.

It is a block diagram which shows schematic structure of the radio | wireless communications system which concerns on this embodiment. It is a figure which shows the fundamental view of the signal source position estimation method of this invention with respect to a horizontal direction (azimuth angle direction). (A) shows an example of the multi-beam antenna gain characteristic when beam forming is performed in the horizontal direction, which is used when obtaining the signal source arrival angle in the horizontal direction. (B) shows a vertical beam. It is a figure which shows the multi-beam antenna gain characteristic at the time of performing the beam forming in the perpendicular direction used when calculating | requiring the signal source arrival angle of a perpendicular direction. (A) is a figure which shows the mode of the beam forming of the horizontal direction in each position estimation station, when providing one position estimation station. (B) is a figure which shows the mode of the beam forming of the perpendicular direction in each position estimation station, when providing one position estimation station. It is a figure which shows schematic structure of the propagation state monitoring apparatus which has a function which calculates | requires a transfer function from a received signal. It is a figure which shows schematic structure of the propagation state monitoring apparatus which has a function which calculates | requires a transfer function from a received signal. It is a figure which shows the test structural example of a propagation state monitoring apparatus. It is a figure which shows the amplitude and phase of a multipath propagation model. It is a figure which shows the characteristic (impulse response) which carried out the inverse Fourier transform of the transfer function measured with the propagation state monitor apparatus. It is a figure which shows the example of the impulse response when the paths (Path) 1 to 3 are obtained. It is a figure which shows a mode that the arrival direction of the path | pass written from the received power difference of a beam is specified using the arrival direction estimation method of a radio wave. (A) And (b) is a figure which shows the operation | movement which matches the arrival direction of a path | pass, and an impulse response. (A) And (b) is a figure which shows the operation | movement which matches the arrival direction of a path | pass, and an impulse response. (A) And (b) is a figure which shows the operation | movement which matches the arrival direction of a path | pass, and an impulse response. It is a figure which shows an example of the position estimation method of the signal source which concerns on this embodiment. It is a flowchart which shows the position estimation procedure of the signal source using map information. It is a figure which shows an example of the correction method which concerns on this embodiment. It is a figure which shows the outline of the arrival direction estimation method of the conventional interference wave.

Explanation of symbols

100 radio base station ANT ₁ reception array antenna ANT ₂ transmission array antenna _AR 1 to Ar _N receiving antenna elements _AT 1 to AT _N transmit antenna elements CNT controller PWM power monitor RBF receive beamformer RV receiver _RV 1 _{~RV N} receiver circuit SD transmission unit SD _{1 to} SD _N transmission circuit SPM spectrum monitor TBF transmission beamformer

Claims (4)

A signal source position estimation method by a position estimation station equipped with a multi-beam antenna capable of beam forming in a horizontal direction and a vertical direction by electronic control,
Performing beam forming in the horizontal direction with the multi-beam antenna to detect a difference in antenna gain between a pair of adjacent beams for each set of beams;
Performing a fast Fourier transform on the received signal to perform channel estimation;
Performing an inverse fast Fourier transform on the signal after channel estimation to calculate an impulse response;
Obtaining a relative delay time between a plurality of paths indicated in the impulse response;
For each path indicated in the impulse response, the antenna gain difference of the detected beam pair and the azimuth angle obtained by referring to the data obtained in a one-to-one correspondence with each beam set are obtained in advance. Estimating an azimuth corresponding to the difference;
The map information including at least terrain information and building information indicating at least the position and shape of the building is acquired, and the map is based on the azimuth angle of at least two paths and the transmission speed of radio waves with reference to the position of the position estimation station. Drawing the predicted arrival route line corresponding to each path above in the order of the relative delay time;
And determining a position at which the predicted arrival route lines of all the paths intersect at the same time on the map. A signal source position estimation method by a position estimation station equipped with a multi-beam antenna capable of beam forming in a horizontal direction and a vertical direction by electronic control,
Performing beam forming in the horizontal direction and the vertical direction with the multi-beam antenna, and detecting a difference in antenna gain between a pair of adjacent beams for each set of beams;
Performing a fast Fourier transform on the received signal to perform channel estimation;
Performing an inverse fast Fourier transform on the signal after channel estimation to calculate an impulse response;
Obtaining a relative delay time between a plurality of paths indicated in the impulse response;
For each path indicated in the impulse response, the antenna gain difference of the detected beam pair and the azimuth angle obtained by referring to the data obtained in a one-to-one correspondence with each beam set are obtained in advance. Estimating an azimuth and elevation corresponding to the difference;
Obtain map information including terrain information and building information indicating at least the position and shape of the building, based on the position of the position estimation station, and based on the azimuth or elevation angle of at least two paths and the transmission speed of radio waves, Drawing the predicted arrival route corresponding to each path on the map in the order of the relative delay time;
And determining a position at which the predicted arrival route lines of all the paths intersect at the same time on the map.   A distance between the head positions indicating the distance between the head positions of each arrival prediction route line is calculated, a time when the distance between the head positions is the minimum is obtained, and an area including all positions on each arrival prediction route line at this time is included. 3. The signal source position estimating method according to claim 1, further comprising a specifying step. The signal according to any one of claims 1 to 3, wherein, when the predicted arrival route line collides with an obstacle on the map, drawing is performed based on a principle of reflection and diffraction of radio waves. Source location estimation method.