Direction estimation device, direction estimation method, and program

Abstract

To provide an azimuth estimation device easily estimating an azimuth even when reception power is temporarily lost.SOLUTION: An azimuth estimation device for receiving radio waves output from a prescribed device in a plurality of directions, and measuring intensity of the received radio waves for every direction of the output radio waves to estimate a radio wave in a preferred direction, the azimuth estimation device includes: a missing determination part for determining whether or not there is a missing direction in the plurality of directions of the received radio waves, and a missing factor determination part, when it is determined that there is the missing direction, determining a factor of the missing based on time change in the intensity of the received radio waves.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to an azimuth estimation device, an azimuth estimation method, and a program.

Background Art

[0002] In research on communication technologies towards Beyond 5G (6G), a virtual terminal in which a user terminal device and peripheral terminals such as a plurality of wearable terminal devices connected to the user terminal device communicate with each other with emphasis is being considered. In the virtual terminal, the THz (terahertz) band is used for information communication between the user terminal device and the peripheral terminals. Here, it is assumed that the beam width becomes narrow in the THz band. When the positional relationship between the user terminal device and the peripheral terminal changes based on the actions of a person wearing a wearable device, if information communication is performed using radio waves with a narrow beam width such as the THz band, it is assumed that the peripheral terminal will easily go out of the range of the beam transmitted from the user terminal device. In order to prevent the peripheral terminal from going out of the range of the beam transmitted from the user terminal device, it is conceivable that the user terminal device predicts the movement of the peripheral terminal and makes the beam follow and output in the predicted direction. Non-Patent Document 1 discloses a technique in which a user terminal device predicts the movement of a peripheral terminal and limits the beam sweep range based on the predicted result.

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

Summary of the Invention

[0004] According to the technology disclosed in Non-Patent Document 1, the user terminal device outputs multiple directional beams with different output directions, and estimates the direction in which the peripheral terminal is located with high accuracy based on the received power received by the peripheral terminal. In addition, the movement vector and dispersion of the peripheral terminal are calculated based on the direction estimated in the past, and the direction in which the user terminal device is moving is predicted. By outputting a beam in the predicted direction, the user terminal device can perform information communication using radio waves with a narrow beamwidth, such as in the THz band. Here, according to the technology disclosed in Non-Patent Document 1, if the received power is temporarily lost, the user terminal device outputs a beam in the position based on the movement prediction, and if the peripheral terminal is not found, it further estimates the direction in which the peripheral terminal is located by performing an omnidirectional search. However, in the THz band, which is being considered for use in Beyond 5G (6G), the beamwidth is narrow, so there is a problem that performing an omnidirectional search takes a long time.

[0005] This invention was made in consideration of these circumstances, and its purpose is to easily estimate direction even when the received power is temporarily lost. [Means for solving the problem]

[0006] (1) One aspect of the present invention is a direction estimation device that receives radio waves output from a predetermined device in multiple directions and estimates a suitable direction of radio waves by measuring the radio wave intensity of the received radio waves for each direction of the output radio waves, Time-series data of radio wave intensity for each sweep direction A missing data cause determination unit that determines the cause of the missing data based on the changes over time, The estimation result storage unit stores the result of estimating the direction in which the predetermined device is located. Based on past direction estimation results 、 The predetermined device The predetermined device for a device that receives radio waves emitted in multiple directions fromThe direction estimation device includes a movement predictor that predicts the position in which the device moves, and a sweep range determination unit that determines a sweep range, which is the range of radio waves output by the predetermined device, based on the information predicted by the movement predictor and the cause of the loss determined by the loss cause determination unit. (2) In one aspect of the present invention, in the orientation estimation device described above, the missing factor determination unit is: Time-series data of radio wave intensity for each sweep direction Based on the trend of changes over time, the sweep range determination unit determines whether the cause of the defect is due to shielding, and if it determines that the cause of the defect is due to shielding, it determines the sweep range based on the position predicted by the movement predictor. (3) In one aspect of the present invention, in the orientation estimation device described above, the missing factor determination unit is: Time-series data of radio wave intensity for each sweep direction Based on the trend of changes over time, the sweep range determination unit determines whether the cause of the loss is due to going outside the communication range, and if it determines that the cause of the loss is due to going outside the communication range, it decides not to output radio waves using the predetermined device. (4) In one aspect of the present invention, in the orientation estimation device described above, the missing factor determination unit is: Time-series data of radio wave intensity for each sweep direction If the range changes rapidly, the sweep range determination unit determines that the cause of the missing data is due to a movement prediction error, and if it determines that the cause of the missing data is due to a movement prediction error, it determines the entire range as the sweep range. (5) In one aspect of the present invention, in the direction estimation device described above, the movement predictor is The aforementioned The trained model is pre-trained using past direction estimation results and the position of the predetermined device as training data. The sweep range determination unit retrains the movement predictor if it determines that the cause of the missing data is due to a movement prediction error. (6) In one aspect of the present invention, the defect factor determination unit is: Time-series data of radio wave intensity for each sweep direction Based on the trend of changes over time, the first determination unit determines whether or not the cause of the loss is due to shielding, and if the cause of the loss is not due to shielding, Time-series data of radio wave intensity for each sweep directionThe system includes a second determination unit that determines, based on the trend of changes over time, whether or not the cause of the loss is due to the system going outside the communication range. (7) In one aspect of the present invention, in the direction estimation device described above, the second determination unit is: Time-series data of radio wave intensity for each sweep direction However, if the change is sudden, it is determined that the cause of the missing data is due to an error in predicting movement. (8) In one aspect of the present invention, in the direction estimation device described above, the first determination unit is: Time-series data of radio wave intensity for each sweep direction This includes a pre-trained model that has been trained using time-dependent changes and information on whether or not the cause of the missing data is due to occlusion as training data. (9) In one aspect of the present invention, in the direction estimation device described above, the second determination unit is: Time-series data of radio wave intensity for each sweep direction This includes a pre-trained model that has been trained using time-dependent changes and information on whether or not the cause of the data loss was due to the device going out of range as training data. (10) In one aspect of the present invention, in the direction estimation device described above, both the trained model included in the first determination unit and the trained model included in the second determination unit are trained using a classifier such as the K-nearest neighbor method. (11) In one aspect of the present invention, the direction estimation device described above further comprises a preprocessing unit which performs preprocessing to determine the range of radio wave intensity measured for each direction of radio waves that is input to the first determination unit. (12) One aspect of the present invention is a direction estimation method for estimating a suitable direction of radio waves by receiving radio waves output from a predetermined device in multiple directions and measuring the radio wave intensity of the received radio waves for each direction of the output radio waves, Time-series data of radio wave intensity for each sweep direction A process for determining the cause of a missing value, which determines the cause of the missing value based on the changes over time, The estimation result storage unit stores the result of estimating the direction in which the predetermined device is located. Based on past direction estimation results 、 The predetermined device The predetermined device for a device that receives radio waves emitted in multiple directions from The orientation estimation method comprises: a sweep range determination step, which determines the sweep range, which is the range of radio waves output by the predetermined device, based on information predicted by a movement predictor that predicts the position of movement and the cause of the loss determined by the loss cause determination step. (13) One aspect of the present invention is a program for causing a computer to receive radio waves output from a predetermined device in a plurality of directions, measure the radio wave intensity of the received radio waves for each direction of the output radio waves, and estimate radio waves in a suitable direction, Time-series data of radio wave intensity for each sweep direction a loss factor determination step of determining a loss factor based on a change over time of The estimation result storage unit stores the result of estimating the direction in which the predetermined device is located. based on past azimuth estimation results 、 the predetermined device The predetermined device for a device that receives radio waves emitted in multiple directions from a sweep range determination step of determining a sweep range, which is a range of radio waves output by the predetermined device, based on information predicted by a movement predictor that predicts a position where the predetermined device moves and a loss factor determined by the loss factor determination step.

Advantages of the Invention

[0007] According to the present invention, even when the received power is temporarily lost, an effect that azimuth estimation can be easily performed is obtained.

Brief Description of the Drawings

[0008] [Figure 1] It is a diagram for explaining an outline of a communication system to which an azimuth estimation device, an azimuth estimation method, and a program according to an embodiment are applied. [Figure 2] It is a functional configuration diagram showing an example of the functional configurations of a transmission device and a reception device according to the present embodiment. [Figure 3] It is a diagram for explaining an omnidirectional search and a search with a limited search range in the beam search method according to the present embodiment. [Figure 4] It is a diagram for explaining the types of loss factors according to the present embodiment. [Figure 5] It is a functional configuration diagram showing an example of the functional configuration of an azimuth estimation device according to the present embodiment. [Figure 6] It is a functional configuration diagram showing an example of the functional configuration of a loss factor determination unit according to the present embodiment. [Figure 7]This is a diagram for explaining the change in received power when the loss factor according to this embodiment is caused by a movement prediction error. [Figure 8] This is a diagram for explaining the change in received power when the loss factor according to this embodiment is caused by going out of the communication range. [Figure 9] This is a flowchart for explaining an example of a method for determining a beam sweep range according to this embodiment. [Figure 10] This is a flowchart for explaining an example of a loss factor determination method according to this embodiment. [Figure 11] This is a block diagram showing an example of the internal configuration of the azimuth estimation device of this embodiment. [Figure 12] This is a functional configuration diagram showing an example of the functional configuration of the sweep range determination unit according to this embodiment. [Figure 13] This is a diagram for explaining the correspondence relationship between the loss factor and the sweep range according to this embodiment. [Figure 14] This is a diagram for explaining the sweep range for each loss factor according to this embodiment.

Mode for Carrying Out the Invention

[0009] Regarding the azimuth estimation device, azimuth estimation method, and program according to an aspect of the present invention, preferred embodiments will be described in detail below with reference to the accompanying drawings. Note that the aspects of the present invention are not limited to these embodiments, and also include those with various modifications or improvements added. That is, the constituent elements described below include those that can be easily assumed by those skilled in the art and substantially the same ones, and the constituent elements described below can be combined as appropriate. Also, various omissions, substitutions, or changes of the constituent elements can be made without departing from the gist of the present invention. Also, in the following drawings, in order to make each configuration easier to understand, the scale, number, etc. in each structure may be different from the scale, number, etc. in the actual structure.

[0010] [Embodiment] Embodiments of the present invention will be described below with reference to the drawings. In the embodiments described below, as an example, the orientation estimation device, orientation estimation method, and program according to this embodiment will be described assuming that they are applied to a communication system in Beyond 5G (6G). However, this embodiment is not limited to this example and can be applied to various communication systems other than Beyond 5G (6G).

[0011] Figure 1 is a diagram illustrating the outline of a communication system to which a direction estimation device, direction estimation method, and program according to one embodiment are applied. The outline of the communication system 1 will be described with reference to this figure. The communication system 1 comprises a plurality of communication devices. In the illustrated example, a first communication device D1, a second communication device D2, and n communication device Dn (where n is a natural number of 1 or more) are shown. Hereinafter, when the plurality of communication devices comprising the communication system 1 are not distinguished, they may simply be referred to as communication device D. Each communication device D communicates information with the others.

[0012] The communication device D may be a user terminal device such as a smartphone or tablet, or a wearable terminal device connected to the user terminal device. Examples of wearable terminal devices include smartwatches, smart glasses, and earphone-type wearable devices. The multiple communication devices D included in the communication system 1 may be held by the user or fixed in a predetermined location.

[0013] The multiple communication devices D included in communication system 1 constitute a virtualized terminal that communicates with each other in coordination. From an external perspective, communication system 1 can be seen as behaving as a single virtualized terminal. For information communication between each communication device D, for example, the terahertz (THz) band is used. However, this embodiment is not limited to this example, and other frequency bands such as the gigahertz (GHz) band may be used. In the following description, radio waves output from communication device D that have narrow directivity may be referred to as beams.

[0014] Here, in the THz frequency range, it is assumed that the beam width of the beam output from the communication device D becomes narrower. As the beam width narrows, the range in which communication is possible between each communication device D is limited. In other words, since the communication devices D communicate information using beams with narrow directivity, it is assumed that if their relative positions change, they will easily move out of the communication range and information communication will become impossible. On the other hand, some of the multiple communication devices D included in the communication system 1 may be wearable devices and may not be used in a fixed position. For example, in the case of information communication between a smartphone and a smartwatch, it is assumed that the relative positions of the devices will change due to the user swinging their arms while walking, and they will easily move out of the communication range. Therefore, according to this embodiment, in order to prevent the communication devices D from moving out of the communication range, the movement of the communication devices D is predicted and the beam is output in the predicted direction, thereby continuing information communication without interruption.

[0015] Figure 2 is a functional configuration diagram showing an example of the functional configuration of the transmitting and receiving devices according to this embodiment. Referring to the same figure, an example of the functional configuration of the communication device D is shown. Multiple communication devices D communicate information by having one of them act as a transmitting device 2 and the other as a receiving device 3. At least one of the transmitting device 2 or the receiving device 3 is equipped with a direction estimation device 10. Figure 2(A) is an example where the direction estimation device 10 is equipped in the receiving device 3, and Figure 2(B) is an example where the direction estimation device 10 is equipped in the transmitting device 2.

[0016] First, with reference to Figure 2(A), an example of the functional configuration of the transmitting device 2 and the receiving device 3 when the receiving device 3 is equipped with an azimuth estimation device 10 will be described. When the receiving device 3 is equipped with an azimuth estimation device 10, the transmitting device 2 will be referred to as the transmitting device 2A and the receiving device 3 will be referred to as the receiving device 3A. The transmitting device 2A includes a beam sweeping unit 21. The beam sweeping unit 21 performs beam sweeping by outputting a beam with narrow directivity in multiple directions by controlling an antenna array, for example, which is composed of multiple antennas. The receiving device 3A includes a beam receiving unit 31 and an azimuth estimation device 10. The beam receiving unit 31 receives radio waves output from the beam sweeping unit 21 and measures the radio wave strength (RSSI; Received Signal Strength Indicator) by measuring the received power of the received radio waves. The beam receiving unit 31 outputs information regarding the measured radio wave strength to the azimuth estimation device 10. The direction estimation device 10 acquires information regarding the radio wave intensity measured by the beam receiving unit 31 and estimates the direction in which the transmitting device 2A is located based on the acquired information. The direction estimation device 10 stores the results of the estimation of the direction in which the transmitting device 2A is located. Based on the stored direction estimation results (i.e., past direction estimation results), the direction estimation device 10 makes a prediction (i.e., movement prediction) about the change in the positional relationship between the transmitting device 2A and the receiving device 3A. Based on the results of the movement prediction, the direction estimation device 10 determines the beam sweep range and outputs information about the determined beam sweep range to the transmitting device 2A. By outputting a beam within the range based on the movement prediction, the transmitting device 2A can search for the direction in which the receiving device 3A is located without outputting a beam in all directions, and can communicate information with the receiving device 3A.

[0017] Next, with reference to Figure 2(B), an example of the functional configuration of the transmitter 2 and receiver 3 when the transmitter 2 is equipped with an azimuth estimation device 10 will be described. When the receiver 3 is equipped with an azimuth estimation device 10, the transmitter 2 will be referred to as transmitter 2B and the receiver 3 as receiver 3B. Transmitter 2B differs from transmitter 2A in that it is equipped with an azimuth estimation device 10. Also, receiver 3B differs from receiver 3A in that it is not equipped with an azimuth estimation device 10. In other words, in the example shown in Figure 2(B), the azimuth estimation processing is performed by transmitter 2B instead of receiver 3A, which is different from the example shown in Figure 2(A). In the example shown in Figure 2(A), information about the determined beam sweep range is output from receiver 3A to transmitter 2A, but in the example shown in Figure 2(B), information about radio wave intensity is output from receiver 3A to transmitter 2A. In the example shown in Figure 2(B), the functional configuration of the direction estimation device 10, the beam sweep unit 21, and the beam receiving unit 31 may be the same as in the example shown in Figure 2(A).

[0018] Figure 3 is a diagram illustrating omnidirectional search and search with a limited search range in the beam search method according to this embodiment. The beam search according to this embodiment will be explained with reference to this figure.

[0019] Figure 3(A) shows an example of omnidirectional search. As shown in the figure, in omnidirectional search, the transmitter 2 outputs radio waves in all directions from which it can output radio waves. Therefore, with omnidirectional search, regardless of the location of the receiver 3, information communication between the transmitter 2 and the receiver 3 can be established as long as the transmitter 2 is located in a direction from which it can output radio waves. However, as mentioned above, the beam width is narrow in the THz band, so omnidirectional search takes time and requires unnecessary power consumption for the search. Therefore, according to this embodiment, the transmitter 2 predicts the location of the receiver 3 and performs the search by limiting the search range.

[0020] Figure 3(B) shows an example of a search with a limited search range. As shown in the figure, the transmitter 2 outputs radio waves in the vicinity of the location where the receiver 3 is predicted to be located. By limiting the search range in this way, the search does not take time and does not consume unnecessary power. However, with a search with a limited search range, if the receiver 3 is not located in the direction of the radio waves output from the transmitter 2 (i.e., if the transmitter 2 has mispredicted the movement of the receiver 3), information communication between the transmitter 2 and the receiver 3 cannot be established, and it becomes necessary to perform an all-directional search again. In this case, the search will require even more time and power consumption. Therefore, it is necessary to accurately predict the movement of the receiver 3 and sweep the beam to a suitable range.

[0021] According to this embodiment, the transmitter 2 predicts the direction in which the receiver 3 is located based on previously estimated directions. The transmitter 2 limits the search range based on the predicted direction and performs a search. Here, if the radio waves output from the transmitter 2 can be continuously received by the receiver 3, the movement of the receiver 3 can be easily predicted. However, if the radio waves output from the transmitter 2 are temporarily not received by the receiver 3 (i.e., the radio waves are lost), the movement of the receiver 3 is predicted based on past movement trajectories, and the search range is limited based on the prediction result and the search is performed. Here, there are thought to be multiple factors that cause the radio waves to be lost. In this embodiment, the factors that cause the radio waves to be lost are identified, and by predicting movement based on the identified loss factors, it is possible to sweep the beam to a suitable range.

[0022] Figure 4 is a diagram illustrating the types of loss factors according to this embodiment. The types of loss factors for radio waves will be explained with reference to this figure. With reference to this figure, examples of cases in which the loss factors for radio waves are, firstly, due to shielding, secondly, due to movement prediction errors, and thirdly, due to movement prediction errors will be explained.

[0023] Figure 4(A) illustrates the case where the cause of the loss is due to shielding. As shown in the figure, the presence of an obstruction between the transmitter 2 and the receiver 3 can cause loss of radio waves emitted from the transmitter 2. Examples of obstructions include human hands and feet. Other examples include clothing and tables. For example, if the receiver 3 moves from a state where there is no loss of radio waves to a position where an obstruction exists between the transmitter 2 and the receiver 3, the transmitter 2 determines the output range of the radio waves based on the past movement of the receiver 3 (for example, based on the movement vector and dispersion). However, the movement trajectory of the receiver 3 may have changed during the period it was in the shadow of the obstruction, and in such cases, the accuracy of direction estimation may decrease.

[0024] Figure 4(B) illustrates the case where the cause of the missing data is due to an error in movement prediction. In this figure, the location where receiver 3 is predicted to be located as a result of movement prediction is shown as receiver 3', and the actual location where receiver 3 is located is shown as receiver 3. The location of receiver 3' is predicted based on the past movement trajectory of receiver 3, for example, by machine learning. Therefore, it is preferable that the location of receiver 3 and the location of receiver 3' are the same. However, if receiver 3 moves in a way that differs from its past movement trajectory, the location of receiver 3 and the location of receiver 3' may differ, as shown in the figure. In such cases where the movement prediction is inappropriate, it is preferable to perform an all-directional search to find the actual receiver 3.

[0025] Figure 4(C) illustrates the case where the cause of the data loss is that the receiver 3 has moved out of the communication range of the transmitter 2. In this figure, the position where the receiver 3 is located at a first time point is shown as receiver 3', and the position where the receiver 3 is located at a second time point, which is later than the first time point, is shown as receiver 3. When the receiver 3 is located at the position shown by receiver 3', the transmitter 2 can communicate information with the receiver 3 normally. However, if the distance between the transmitter 2 and the receiver 3 increases, for example, as shown in the figure, the receiver 3 may be located at the position shown by receiver 3, in which case the receiver 3 will move out of the communication range of the transmitter 2, and information communication may become impossible. In this case, when the receiver 3 is out of the communication range of the transmitter 2, it is impossible to find the receiver 3 no matter how much searching is performed. In this case, it is preferable for the transmitter 2 not to search for the receiver 3 (i.e., not to output a beam to the receiver 3).

[0026] Figure 5 is a functional configuration diagram showing an example of the functional configuration of the direction estimation device according to this embodiment. An example of the functional configuration of the direction estimation device 10 will be described with reference to this figure. The direction estimation device 10 includes a sweep result storage unit 11, a direction estimation unit 12, an estimation result storage unit 13, a missing data presence / absence determination unit 14, a missing data cause determination unit 15, and a sweep range determination unit 16. Each of these functional units is implemented, for example, using an electronic circuit. In addition, each functional unit may be internally equipped with storage means such as semiconductor memory or a magnetic hard disk drive, as needed. Furthermore, each function may be implemented by a computer and software.

[0027] The sweep result storage unit 11 acquires information regarding the beam sweep direction and received power from the beam receiving unit 31. The beam sweep direction is the direction of the narrowly directivity beam output from the transmitting device 2. The received power is the power of the beam received by the receiving device 3, i.e., the radio wave intensity, corresponding to the direction of the beam. The sweep result storage unit 11 stores the acquired information. The information acquired by the sweep result storage unit 11 may include time information in advance, or the sweep result storage unit 11 may store the acquired information in association with the time it was acquired.

[0028] The direction estimation unit 12 identifies the direction with the highest radio wave intensity at each time based on the information stored in the sweep result storage unit 11. The identified direction is the direction in which the receiving device 3 is located as seen from the transmitting device 2 (or the direction in which the transmitting device 2 is located as seen from the receiving device 3). The direction estimation unit 12 may also estimate the trajectory of the receiving device 3 as seen from the transmitting device 2 (or the trajectory of the transmitting device 2 as seen from the receiving device 3) based on the time-dependent changes in the identified direction. Based on the estimated trajectory, the direction estimation unit 12 estimates the direction of the receiving device 3 as seen from the transmitting device 2 at a predetermined time. The direction estimation unit 12 stores the result of the direction estimation in the estimation result storage unit 13.

[0029] The estimation result storage unit 13 stores information about the direction estimated by the direction estimation unit 12. The estimation result storage unit 13 stores the information about the direction estimated by the direction estimation unit 12 in association with the time. It can also be said that the estimation result storage unit 13 stores past direction estimation results.

[0030] The loss detection unit 14 determines whether or not a loss has occurred in the received radio waves (i.e., whether or not there is a loss). Specifically, the loss detection unit 14 determines whether or not there is a direction with a loss among the multiple directions in which the radio waves were received. The loss detection unit 14 may determine that a loss has occurred if the radio wave intensity in at least one direction is below a predetermined value. The loss detection unit 14 outputs information regarding the determination of whether or not a loss has occurred to the loss cause determination unit 15.

[0031] The missing signal cause determination unit 15 acquires the direction estimation result stored in the estimation result storage unit 13 and obtains information regarding the presence or absence of missing signals from the missing signal presence / absence determination unit 14. If the missing signal cause determination unit 14 determines that there is a direction with missing signals, the missing signal cause determination unit 15 determines the cause of the missing signals based on the time-dependent change in the signal strength of the received radio waves. Details regarding the determination of missing signal causes will be described later with reference to Figure 6, etc. The missing signal cause determination unit 15 outputs the information regarding the determined missing signal cause to the sweep range determination unit 16.

[0032] The sweep range determination unit 16 acquires the direction estimation result stored in the estimation result storage unit 13 and acquires the missing factor determination result from the missing factor determination unit 15. Based on the acquired information, the sweep range determination unit 16 determines the beam sweep range. The beam sweep range determined by the sweep range determination unit 16 is, in other words, the direction of the beam output from the transmitter 2. The direction of the beam output from the transmitter may be, firstly, all directions, secondly, a predetermined direction that is a narrower range than all directions, or thirdly, no output. The sweep range determination unit 16 outputs information regarding the determined sweep range to the beam sweep unit 21.

[0033] Figure 6 is a functional configuration diagram showing an example of the functional configuration of the defect cause determination unit according to this embodiment. An example of the functional configuration of the defect cause determination unit 15 will be described with reference to the figure. The defect cause determination unit 15 comprises a preprocessing unit 151, a first determination unit 152, a second determination unit 153, and an output unit 154.

[0034] The preprocessing unit 151 acquires the direction estimation results stored in the estimation result storage unit 13 and obtains information regarding the presence or absence of missing data from the missing data determination unit 14. If the missing data determination unit 14 determines that there is a direction with missing data, the preprocessing unit 151 performs preprocessing on the information to be input to the first determination unit 152. The information to be input to the first determination unit 152 is the time-series data of the direction estimation results. In this embodiment, the beam sweep range is a variable algorithm. Therefore, the preprocessing unit 151 performs preprocessing to identify the range to be input to the first determination unit 152 and to adjust the format of the information to be input to the first determination unit 152. In other words, preprocessing can be described as the process of identifying the range to be input to the first determination unit 152 from the radio wave intensity measured for each direction of radio waves. Furthermore, since the beam sweep range and sweep direction output by the transmitting device 2 change over time, preprocessing can also be described as the process of converting the data into a format that is easy for the first determination unit 152 to process.

[0035] The first determination unit 152 obtains pre-processed information from the pre-processing unit 151. Based on the obtained information, the first determination unit 152 performs a first determination. The first determination is whether or not the cause of the loss is due to shielding. The first determination is made based on the trend of changes in the received radio wave intensity over time. For example, the first determination unit 152 may determine that the cause of the loss is due to shielding if, among the radio wave intensity received in multiple directions, there is a direction with low radio wave intensity. The first determination can also be described as a determination to distinguish whether or not the cause of the loss is due to shielding. Furthermore, if the first determination unit 152 determines that the cause of the loss is due to shielding, it may perform estimation to identify the shielded section.

[0036] The first determination unit 152 may perform the first determination by machine learning. When the first determination is performed by machine learning, the first determination unit 152 includes a pre-trained model. This pre-trained model is pre-trained by supervised learning using the time-dependent changes in the intensity of the received radio waves and information on whether or not the cause of the loss is due to shielding as training data. It is preferable that this pre-trained model be trained using the K-nearest neighbors algorithm.

[0037] The second determination unit 153 obtains pre-processed information from the pre-processing unit 151 and obtains the result of the first determination from the first determination unit 152. Based on the obtained information, the second determination unit 153 performs a second determination. The second determination is performed when the cause of the loss is not due to shielding. The second determination is a determination of whether or not the cause of the loss is due to going outside the communication range. The second determination unit 153 performs the second determination based on pre-processed information regarding the direction estimation result, that is, the trend of changes in the received radio wave intensity over time. For example, if the received radio wave intensity changes rapidly, the second determination unit 153 may determine that the cause of the loss is due to a movement prediction error. In this case, if the cause of the loss is not due to going outside the communication range, the second determination unit 153 may determine that a movement prediction error is the cause.

[0038] The second determination unit 153 may perform a second determination using machine learning. When the second determination is performed using machine learning, the second determination unit 153 includes a pre-trained model. This pre-trained model is pre-trained using supervised learning, with training data consisting of the time-dependent changes in the signal strength of the received radio waves and information on whether or not the cause of the loss is due to going outside the communication range. It is preferable that this pre-trained model be trained using the K-nearest neighbors algorithm.

[0039] The output unit 154 obtains a first determination result from the first determination unit 152 and a second determination result from the second determination unit 153. Based on the obtained results, the output unit 154 identifies the cause of radio wave loss. The output unit 154 outputs the identified cause of radio wave loss to the sweep range determination unit 16.

[0040] Next, referring to Figures 7 and 8, we will explain an example of how the received power changes when the relative positions of the transmitter 2 and the receiver 3 change. Furthermore, referring to Figures 7 and 8, we will explain why it is possible to determine the cause of the data loss from the trend of the change in received power.

[0041] Figure 7 illustrates the change in received power when the cause of the loss in this embodiment is due to a movement prediction error. Figure 7(A) shows the beam sweep range and the positional relationship between the transmitter 2 and the receiver 3 when the cause of the loss is due to a movement prediction error. Figure 7(B) shows the change in received power over time in the positional relationship shown in Figure 7(A). In this figure, the position where the receiver 3 is predicted to be located as a result of the movement prediction is shown as receiver 3', and the position where the receiver 3 is actually located is shown as receiver 3. In this case, the transmitter 2 outputs a beam towards receiver 3', which is the position where the receiver 3 is predicted to be located. However, since the position where the receiver 3 is actually located is receiver 3, the beam is output in the wrong direction. In this case, the received power will drop sharply.

[0042] Figure 8 illustrates the change in received power when the signal loss in this embodiment is caused by the receiver moving out of the communication range. Figure 8(A) shows the beam sweep range and the positional relationship between the receiver 2 and the receiver 3 when the signal loss is caused by the receiver 3 moving out of the communication range of the transmitter 2. Figure 8(B) shows the change in received power over time in the positional relationship shown in Figure 8(A). In this figure, the position where the receiver 3 is located at the first time point is shown as receiver 3', and the position where the receiver 3 is located at the second time point, which is after the first time point, is shown as receiver 3. In this case, the transmitter 2 continues to output a beam in the direction where the receiver 3 is located, both at the first and second time points. However, since the receiver 3 gradually moves away from the transmitter 2, the received power will decrease slowly.

[0043] As explained with reference to Figures 7 and 8, the trend in changes in received power differs depending on whether the loss is due to an error in movement prediction or to moving out of the communication range. Therefore, it is possible to determine the cause of radio wave loss based on the trend in changes in received power.

[0044] Figure 9 is a flowchart illustrating an example of a method for determining the beam sweep range according to this embodiment. An example of a method for determining the beam sweep range according to this embodiment will be explained with reference to this figure.

[0045] First, the transmitting device 2 performs a beam sweep in a predetermined direction (step S11). The receiving device 3 receives the beam output from the transmitting device 2 and estimates the direction in which the transmitting device 2 is located based on the radio wave intensity of the received beam (step S12). Specifically, the direction estimation may be performed based on previously estimated direction estimation results (for example, the direction estimation result from the previous step), i.e., time-series data of direction estimation results.

[0046] Next, it is estimated whether the received power of the beam received by the receiving device 3 is below a threshold (step S13). If the received power is below the threshold, the process proceeds to step S14. If the received power is not below the threshold, the process proceeds to step S15. If the received power is below the threshold (i.e., step S13; YES), the cause of the received power deficit is determined (step S14). Depending on the determined cause of the received power deficit, the beam sweep range by the movement predictor is determined (step S16), or the beam sweep range is adaptively determined (step S17). If the received power is not below the threshold (i.e., step S13; NO), the beam sweep range by the movement predictor is determined (step S15).

[0047] Figure 10 is a flowchart illustrating an example of a method for determining the cause of missing data according to this embodiment. An example of the method for determining the cause of missing data according to this embodiment will be explained with reference to this figure. Note that the process described with reference to this figure is an example of a process performed by the missing data cause determination unit 15.

[0048] First, the missing data determination unit 15 performs preprocessing on the time-series data of the direction estimation results (step S21). Next, the missing data determination unit 15 determines the occlusion interval based on the preprocessed time-series data (step S22). The determination of the occlusion interval is performed by a pre-trained prediction model using the relationship between the fluctuation trend of the direction estimation results and occlusion as training data. It is preferable to use the K-nearest neighbor method to determine the occlusion interval. Here, for example, at least one of the transmitting device 2 and the receiving device 3 may be a wearable device worn on the human body. Therefore, movement prediction can be performed by using a prediction model that has learned the relationship between human body movement and occlusion. Human body movement can be estimated, for example, based on the time-series data of the direction estimation results. Thus, it is possible to determine the occlusion interval based on the time-series data of the direction estimation results.

[0049] If the loss cause determination unit 15 determines that the receiving device 3 is located in a shielded section (i.e., step S23; YES), it determines that the loss of radio waves is due to shielding (step S26).

[0050] Furthermore, if the loss cause determination unit 15 does not determine that the receiving device 3 is located in the shielded section (i.e., step S23; NO), it performs a further determination (step S24). This further determination is based on the fluctuation trend of radio wave intensity for each sweep direction by the transmitting device 2, and determines whether the loss is due to moving out of the communication range or due to a movement prediction error. A different prediction model than the one used in the determination in step S23 may be used for this determination. It is preferable that this determination be performed using the K-nearest neighbor method.

[0051] The loss cause determination unit 15 determines that the cause is going outside the communication range if the fluctuation trend of the radio wave intensity for each sweep direction by the transmitting device 2 can be classified into a predetermined trend (first trend), and proceeds to step S27 (i.e., step S25; YES). The loss cause determination unit 15 determines that the cause of the loss is due to going outside the communication range.

[0052] Furthermore, the data loss cause determination unit 15 determines that the cause is not going outside the communication range if the fluctuation trend of the radio wave intensity for each sweep direction by the transmitting device 2 can be classified into a predetermined trend (second trend) (or if it cannot be classified), and proceeds to step S28 (i.e., step S25; NO). The data loss cause determination unit 15 determines that the cause of the data loss is due to a movement prediction error.

[0053] Figure 11 is a block diagram showing an example of the internal configuration of the direction estimation device of this embodiment. At least some of the functions of the direction estimation device 10 can be realized using a computer. As shown in the figure, the computer consists of a central processing unit 901, RAM 902, input / output ports 903, input / output devices 904 and 905, etc., and a bus 906. The computer itself can be realized using existing technology. The central processing unit 901 executes instructions contained in programs read from RAM 902, etc. The central processing unit 901 writes data to RAM 902, reads data from RAM 902, and performs arithmetic and logical operations according to each instruction. RAM 902 stores data and programs. Each element contained in RAM 902 has an address and can be accessed using that address. RAM stands for "Random Access Memory". Input / output ports 903 are ports for the central processing unit 901 to exchange data with external input / output devices, etc. Input / output devices 904 and 905 are input / output devices. Input / output devices 904 and 905 exchange data with the central processing unit 901 via input / output port 903. Bus 906 is a common communication channel used within the computer. For example, the central processing unit 901 reads and writes data to RAM 902 via bus 906. Also, for example, the central processing unit 901 accesses input / output ports via bus 906.

[0054] Figure 12 is a functional configuration diagram showing an example of the functional configuration of the sweep range determination unit according to this embodiment. An example of the functional configuration of the sweep range determination unit 16 will be described with reference to the figure. The sweep range determination unit 16 comprises a movement predictor 161 and a control unit 162.

[0055] The movement predictor 161 acquires the direction estimation results stored in the estimation result storage unit 13. The direction estimation results stored in the estimation result storage unit 13 are, in other words, time-series data of the direction estimation results. Based on the acquired information, the movement predictor 161 predicts the movement position of the transmitter 2 relative to the receiver 3 (or the position of the transmitter 3 relative to the transmitter 2). It is preferable for the movement predictor 161 to perform movement prediction using machine learning. In this case, the movement predictor 161 may include a pre-trained model that has been trained in advance using past direction estimation results and the position of the transmitter 2 as training data. The movement predictor 161 outputs the result of the movement prediction to the control unit 162.

[0056] The control unit 162 acquires the movement prediction result from the movement predictor 161 and the cause of the missing data from the missing data cause determination unit 15. The sweep range determination unit 16 determines the sweep range, which is the range of the radio waves output by the transmitter 2, based on the information predicted by the movement predictor 161 and the cause of the missing data determined by the missing data cause determination unit 15.

[0057] Here, the cause of the defect determined by the defect cause determination unit 15 may be, firstly, due to shielding, secondly, due to a movement prediction error, or thirdly, due to a movement prediction error. The control unit 162 determines the sweep range according to these causes of the defect. Note that the causes of the defect determined by the defect cause determination unit 15 are not limited to the examples described above, and other factors may exist. Furthermore, while it is preferable that the sweep range determined by the control unit 162 be determined according to the cause of the defect, it may also be determined based on factors other than the cause of the defect.

[0058] Figure 13 is a diagram illustrating the correspondence between the defect factors and the sweep range according to this embodiment. The correspondence between the defect factors and the sweep range will be explained with reference to this figure.

[0059] As shown in the figure, if it is determined that the cause of the loss is a loss due to shielding, the sweep range determination unit 16 determines the sweep range based on the position predicted by the movement predictor 161. Here, if the loss of radio waves is due to shielding, the receiving device 3 may enter the shadow of the shielding object and then emerge from behind it. In this case, the movement predictor 161 determines the sweep range based on the position predicted by the movement predictor 161 by temporarily stopping the output of radio waves during the period when the receiving device 3 is hidden behind the shielding object, or by outputting a beam around the position where the receiving device 3 emerges from behind the shielding object.

[0060] Furthermore, if it is determined that the cause of the data loss is due to the device moving out of the communication range, the sweep range determination unit 16 decides not to sweep. Not sweeping means that the transmitting device 2 does not emit radio waves. If the receiving device 3 is outside the communication range of the transmitting device 2, the receiving device 3 cannot receive the radio waves even if the transmitting device 2 emits them. Therefore, by not emitting radio waves from the transmitting device 2, unnecessary radio wave output can be suppressed, and power consumption can be reduced.

[0061] Furthermore, if it is determined that the cause of the data loss is due to a movement prediction error, the sweep range determination unit 16 determines the entire range as the sweep range. In this case, if the cause of the data loss is due to a movement prediction error, the position of the receiving device 3 as seen from the transmitting device 2 is unknown. Therefore, the transmitting device 2 searches for the receiving device 3 by outputting a beam across the entire range in which it can output.

[0062] Furthermore, if it is determined that the cause of the missing data is due to a movement prediction error, it can be said that the accuracy of the movement predictor 161 is low. Therefore, it is preferable to improve the accuracy of movement prediction by retraining the trained model included in the movement predictor 161. If the sweep range determination unit 16 determines that the cause of the missing data is due to a movement prediction error, it uses the newly obtained information as training data to retrain the trained model included in the movement predictor 161.

[0063] Figure 14 is a diagram illustrating the sweep range for each defect factor according to this embodiment. The sweep range for each defect factor determined by the sweep range determination unit 16 will be explained with reference to this figure.

[0064] Figure 14(A) is a diagram illustrating the case where the cause of the loss is due to shielding. When the radio waves output from the transmitting device 2 are lost due to the presence of an obstacle between the transmitting device 2 and the receiving device 3, the sweep range determination unit 16 sets the sweep range to the position where the receiving device 3 is estimated to emerge from behind the obstacle, as shown in the figure. The position where the receiving device 3 is estimated to emerge from behind the obstacle is determined based on past azimuth estimation results.

[0065] Figure 14(B) illustrates the case where the cause of the data loss is due to an error in movement prediction. In this figure, the location where the receiver 3 is predicted to be located as a result of the movement prediction is shown as receiver 3', and the location where the receiver 3 is actually located is shown as receiver 3. In this case, as shown in the figure, by outputting a beam across the entire range, the transmitter 2 can search for the receiver 3 even if the predicted location differs from the actual location.

[0066] Figure 14(C) illustrates the case where the cause of the loss is that the receiver 3 has moved out of the communication range of the transmitter 2. In this figure, the position of the receiver 3 at the first time point is shown as receiver 3', and the position of the receiver 3 at the second time point, which is after the first time point, is shown as receiver 3. Receiver 3 is outside the communication range of the transmitter 2. Because receiver 3 is outside the communication range of the transmitter 2, in this case, the transmitter 2 does not emit a beam.

[0067] [Summary of Embodiments] According to this embodiment, the direction estimation device 10 receives radio waves output in multiple directions from a predetermined device such as a transmitting device 2, and estimates the radio waves in a suitable direction by measuring the radio wave intensity of the received radio waves for each direction of the output radio waves. Furthermore, the direction estimation device 10 includes a loss factor determination unit 15 to determine the loss factor based on the time-dependent change in the radio wave intensity of the received radio waves, and includes a sweep range determination unit 16 to determine the sweep range, which is the range of radio waves output by the transmitting device 2, based on the information predicted by the movement predictor 161 and the loss factor determined by the loss factor determination unit 15. In other words, the direction estimation device 10 determines the loss factor and determines the sweep range based on the determined loss factor. Therefore, because the direction estimation device 10 can determine the sweep range based on the loss factor, it can search for the device to communicate with in a short time even if the received power is temporarily lost.

[0068] Here, the communication system 1 includes multiple communication devices D. Even if information communication between any two of the multiple communication devices D included in the communication system 1 is interrupted, it may be possible to enable information communication between the multiple communication devices D included in the communication system 1 by routing the communication through the other communication devices D, allowing the system to behave as a single virtualized terminal. According to this embodiment, even if information communication between any two of the communication devices D is interrupted, information communication can be maintained for the entire communication system 1 by switching the communication target to another communication device D, which is a more suitable relay device.

[0069] Furthermore, according to the embodiment described above, the loss factor determination unit 15 determines whether the loss is due to shielding based on the trend of changes in the received radio wave intensity over time, and if it is determined that the loss is due to shielding, the sweep range determination unit 16 determines the sweep range based on the position predicted by the movement predictor 161. Therefore, with the direction estimation device 10, even if the loss is due to shielding, the device to be communicated can be searched for in a short time.

[0070] Furthermore, according to the embodiment described above, the loss cause determination unit 15 determines whether the loss is due to the signal going outside the communication range, based on the trend of changes in the received radio wave intensity over time. If the sweep range determination unit 16 determines that the loss is due to the signal going outside the communication range, it decides not to output radio waves from the transmitting device 2. Therefore, the direction estimation device 10 can suppress unnecessary power consumption when the loss is due to the signal going outside the communication range.

[0071] Furthermore, according to the embodiment described above, the missing signal cause determination unit 15 determines that the cause of the missing signal is due to a movement prediction error when the signal strength of the received radio waves changes rapidly, and the sweep range determination unit 16 determines the entire range as the sweep range when it is determined that the cause of the missing signal is due to a movement prediction error. Therefore, the direction estimation device 10 can reliably search for the receiving device 3 when the cause of the missing signal is due to a movement prediction error.

[0072] Furthermore, according to the embodiment described above, the movement predictor 161 is a pre-trained model that has been learned in advance using past direction estimation results and the position of the transmitting device 2 as training data. If the sweep range determination unit 16 determines that the cause of the missing data is due to a movement prediction error, it retrains the movement predictor 161. Therefore, according to this embodiment, even if the accuracy of the movement prediction by the movement predictor 161 is not high, the accuracy of the movement prediction can be improved by collecting actual position data as training data and performing additional training.

[0073] Furthermore, this will enable an overall improvement in service quality in mobile communication systems such as 5G systems, thereby contributing to Goal 9 of the United Nations-led Sustainable Development Goals (SDGs): "Build resilient infrastructure, promote sustainable industrialization and foster innovation."

[0074] Although embodiments of the present invention have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments, and design modifications and the like are also included within the scope of the gist of the present invention.

[0075] Alternatively, computer programs for realizing the functions of each of the above-mentioned devices may be recorded on a computer-readable recording medium, and the programs recorded on this recording medium may be loaded into a computer system and executed. Note that the term "computer system" here may include hardware such as an operating system and peripheral devices. Furthermore, "computer-readable recording media" refers to writable non-volatile memory such as flexible disks, magneto-optical disks, ROMs, and flash memory, portable media such as DVDs (Digital Versatile Discs), and storage devices such as hard disks built into computer systems.

[0076] Furthermore, "computer-readable recording media" includes volatile memory (such as DRAM (Dynamic Random Access Memory)) within computer systems that act as servers or clients when a program is transmitted via a network such as the Internet or a communication line such as a telephone line, which retains the program for a certain period of time. In addition, the above program may be transmitted from the computer system that stores the program in a memory device, etc., to another computer system via a transmission medium or by transmission waves within the transmission medium. Here, the "transmission medium" for transmitting the program refers to a medium that has the function of transmitting information, such as a network such as the Internet or a communication line such as a telephone line. Furthermore, the above program may be intended to implement some of the functions described above. It may also be a so-called differential file (differential program) that can implement the aforementioned functions in combination with programs already recorded in the computer system. [Explanation of symbols]

[0077] 1...Communication system, D...Communication device, 2...Transmitter, 3...Receiver, 21...Beam sweep unit, 31...Beam receiving unit, 10...Directional estimation device, 11...Sweep result storage unit, 12...Directional estimation unit, 13...Estimation result storage unit, 14...Defect detection unit, 15...Defect factor detection unit, 16...Sweep range determination unit, 151...Preprocessing unit, 152...First determination unit, 153...Second determination unit, 154...Output unit, 161...Movement predictor, 162...Control unit

Claims

1. A direction estimation device that receives radio waves emitted in multiple directions from a predetermined device, and estimates the radio waves of a suitable direction by measuring the radio wave intensity of the received radio waves for each direction of the emitted radio waves, A missing data source determination unit determines the cause of the missing data based on the time-dependent changes in time-series data of radio wave intensity for each sweep direction, The system includes a movement predictor that predicts the position in which the predetermined device moves relative to a device that receives radio waves output in multiple directions from the predetermined device, based on past direction estimation results stored in an estimation result storage unit that stores the results of estimating the direction in which the predetermined device is located, and a sweep range determination unit that determines a sweep range, which is the range of radio waves output by the predetermined device, based on the information predicted by the movement predictor and the cause of the loss determined by the loss cause determination unit. A direction estimation device equipped with the following features.

2. The aforementioned loss cause determination unit determines whether the cause of the loss is due to shielding, based on the trend of time-series changes in the radio wave intensity data for each sweep direction. If the sweep range determination unit determines that the cause of the defect is due to shielding, it determines the sweep range based on the position predicted by the movement predictor. The direction estimation device according to claim 1, comprising:

3. The aforementioned loss cause determination unit determines whether the loss is due to the radio wave intensity going outside the communication range, based on the trend of changes over time in the time-series data of the radio wave intensity for each sweep direction. If the sweep range determination unit determines that the cause of the loss is due to the device moving outside the communication range, it decides not to output radio waves using the predetermined device. The direction estimation device according to claim 1 or claim 2.

4. The missing data source determination unit determines that if the time-series data of radio wave intensity for each sweep direction changes abruptly, the missing data source is due to a movement prediction error. If the sweep range determination unit determines that the cause of the missing data is due to a movement prediction error, it determines the entire range as the sweep range. The direction estimation device according to claim 1 or claim 2.

5. The aforementioned movement predictor is a pre-trained model that has been learned in advance using the past direction estimation results and the position of the predetermined device as training data. If the sweep range determination unit determines that the cause of the missing data is due to a movement prediction error, it performs a retraining of the movement predictor. The direction estimation device according to claim 4.

6. The missing factor determination unit is, A first determination unit determines whether the cause of the loss is due to shielding, based on the trend of changes over time in time-series data of radio wave intensity for each sweep direction. A second determination unit, when the cause of the loss is not due to shielding, determines whether the cause of the loss is due to moving out of the communication range, based on the trend of changes over time in the time-series data of radio wave intensity for each sweep direction. The direction estimation device according to claim 1, comprising:

7. The second determination unit determines that if the time-series data of radio wave intensity for each sweep direction changes abruptly, the cause of the missing data is due to a movement prediction error. The direction estimation device according to claim 6.

8. The first determination unit includes a pre-trained model that has been trained using the time-series changes in radio wave intensity data for each sweep direction and information on whether or not the cause of the loss is due to shielding as training data. The direction estimation device according to claim 7.

9. The second determination unit includes a pre-trained model that has been trained using as training data the change in time-series data of radio wave intensity for each sweep direction and information on whether or not the cause of the loss is due to going outside the communication range. The direction estimation device according to claim 7.

10. Both the trained model included in the first determination unit and the trained model included in the second determination unit are trained using a classifier such as the K-nearest neighbors method. The direction estimation device according to claim 8 or claim 9.

11. The aforementioned defect cause determination unit further includes a preprocessing unit that performs preprocessing to identify the range of radio wave intensity measured for each direction of radio waves that will be input to the first determination unit. The direction estimation device according to any one of claims 6 to 9.

12. A direction estimation method that estimates the direction of radio waves by receiving radio waves emitted in multiple directions from a predetermined device and measuring the radio wave intensity of the received radio waves for each direction of the emitted radio waves, A missing data source determination process that determines the cause of the missing data based on the time-dependent changes in time-series data of radio wave intensity for each sweep direction, Based on past direction estimation results stored in an estimation result storage unit that stores the results of estimating the direction in which the predetermined device is located, a sweep range determination step determines the sweep range, which is the range of radio waves output by the predetermined device, based on information predicted by a movement predictor that predicts the position in which the predetermined device moves relative to a device that receives radio waves output in multiple directions from the predetermined device, and the factors of the missing values ​​determined by the missing value factor determination step. A method for estimating direction, comprising the following characteristics.

13. On the computer, A program that receives radio waves emitted in multiple directions from a predetermined device, and estimates the radio waves in a suitable direction by measuring the radio wave intensity of the received radio waves for each direction of the emitted radio waves, A missing data source determination step that determines the cause of the missing data based on the time-dependent changes in time-series data of radio wave intensity for each sweep direction, A sweep range determination step determines a sweep range, which is the range of radio waves output by the predetermined device, based on information predicted by a movement predictor that predicts the position in which the predetermined device moves relative to a device that receives radio waves output in multiple directions from the predetermined device, based on past direction estimation results stored in an estimation result storage unit that stores the results of estimating the direction in which the predetermined device is located, and the factors of the missing information determined in the missing factor determination step. A program that executes the command.

Images