Estimation apparatus, estimation method, and program

Abstract

To provide a technique for improving the accuracy of location information of an article in a system for managing a location of the article.SOLUTION: An estimation apparatus estimates a location of a wireless device based on a first distance between the wireless device and a first communication apparatus, the first distance being determined based on a result of measurement of a first signal which the first communication apparatus causes the wireless device to transmit by the first communication apparatus, a second distance between the wireless device and a second communication apparatus, the second distance being determined based on a result of measurement of the first signal which the first communication apparatus causses the wireless device to transmit by the second communication apparatus, first location information indicating a location of the first communication apparatus, and second location information indicating a location of the second communication apparatus.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to a technique for estimating location information of a wireless device. [Background technology]

[0002] In logistics, inventory management, and the like, systems that use RFID readers and RFID tags to manage the locations of items are widely used. RFID is an abbreviation for Radio Frequency Identification. As an example, in a location management system using RFID, a user carries an RFID reader and reads RFID tags attached to items at the destination of the user's movement, thereby making the management of items more efficient. Patent Document 1 describes a technology that increases the probability of detecting an RFID tag when a user or the like is moving at high speed by reading RFID tags while operating multiple RFID readers in cooperation with each other. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4990874 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention provides a technique for improving the accuracy of item location information in a system for managing the locations of items. [Means for solving the problem]

[0005] An estimation device according to one aspect of the present invention estimates a position of a wireless device based on a first distance between the wireless device and the first communication device, which is determined based on a result of the first communication device measuring a first signal that the first communication device caused to be transmitted to the wireless device, a second distance between the wireless device and the second communication device, which is determined based on a result of the second communication device measuring a first signal that the first communication device caused to be transmitted to the wireless device, first position information indicating the position of the first communication device, and second position information indicating the position of the second communication device. Effect of the Invention

[0006] According to the present invention, it is possible to improve the accuracy of item location information in a system for managing the locations of items. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a position management system. [Diagram 2] FIG. 2 illustrates an example of a functional configuration of a communication device. [Diagram 3] 11 is a diagram illustrating an example of a sequence when a communication device performs measurement in cooperation with another communication device. [Figure 4] 1 is a diagram illustrating an example of a sequence for measuring a distance between a communication apparatus and a wireless device. [Diagram 5] FIG. 1 illustrates an example method for estimating the location of a wireless device. [Figure 6] FIG. 2 illustrates an example of a hardware configuration of a communication device. [Figure 7] FIG. 2 is a diagram illustrating an example of a functional configuration of an information processing device. [Figure 8] FIG. 1 illustrates an example flowchart of a process for estimating the location of a wireless device. [Figure 9] FIG. 13 illustrates an example flowchart of a process for performing wireless device detection. [Figure 10] FIG. 11 illustrates an example of a flowchart of a cooperation process between communication devices. [Figure 11]FIG. 13 is a diagram illustrating an example of an operation when estimating the position of a wireless device. [Figure 12] FIG. 13 illustrates an example flowchart of a process for estimating the location of a wireless device. [Figure 13] FIG. 13 illustrates an example of a flowchart of a handover process between communication devices. [Figure 14] FIG. 13 is a diagram illustrating an example of an operation when estimating the position of a wireless device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, the embodiments will be described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe a number of features, not all of these features are essential to the invention, and the features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0009] (Embodiment 1) (System Configuration) FIG. 1 shows an example of the configuration of a location management system according to this embodiment. The location management system according to this embodiment includes, for example, wireless devices 101, 102, and 103, communication devices 111 and 112, and an information processing device 120. The wireless devices 101 to 103 may be called the wireless device 100 without distinction. Also, the communication devices 111 and 112 may be called the communication device 110 without distinction. In this embodiment, the communication device 110 is configured to communicate with the wireless device 100 or detect the wireless device 100. The location management system according to this embodiment uses the wireless device 100 to manage the location information of an item that is a management target of this system. In this system, as an example, the communication device 110 moves with a person, a machine, or the like to detect the wireless device 100 that exists in a wide range. Also, the communication device 110 links the information recorded in the detected wireless device 100 with the location information and notifies the information processing device 120.

[0010] The wireless device 100 communicates with the communication device using radio waves such as electromagnetic waves (radio waves) to notify the communication device 110 of information recorded in the wireless device 100. In this embodiment, the wireless device 100 is, for example, an RFID tag that communicates by Radio Frequency Identification (RFID). The wireless device 100 is not limited to an RFID tag, and may be a Near Field Communication (NFC) device or the like. In this embodiment, the wireless device 100 is a passive RFID tag, but may be an active RFID tag or the like. The RFID tag includes a small integrated circuit (IC) chip with built-in memory and an antenna, and stores identification information and other information for identifying the RFID tag in the memory. In this embodiment, this identification information is called a tag ID. The other information may include information that can be read and written by a user who uses the RFID tag. The passive RFID tag operates using the energy of radio waves such as UHF band radiated by an RFID reader described later, and transmits information such as the tag ID recorded in the RFID tag as a radio signal from the antenna. That is, a passive RFID tag can transmit a radio signal only in response to radio waves from an RFID reader. On the other hand, an active RFID tag has a built-in battery and can transmit a radio signal without receiving radio waves from an RFID tag. Unless otherwise specified, the RFID tag used in the following discussion may be either a passive type or an active type. UHF stands for Ultra High Frequency. The radio waves emitted by the RFID reader are not limited to the UHF band, and may be the HF band, VHF band, microwave band, etc. HF stands for High Frequency, and VHF stands for Very High Frequency. In this embodiment, the types of RFID tags are a reference tag whose position (coordinates, etc.) is known, and an item tag whose position is unknown. The position management system may include RFID tags of other types than the reference tag and the item tag.

[0011] The reference tag is used to generate location information for identifying the location of the RFID reader by reading the tag ID by the RFID reader. The location information of the reference tag may be written in advance in a memory built into the reference tag. Also, the location information of the reference tag may be acquired by an inquiry to an information processing device using the tag ID of the reference tag. In this embodiment, the wireless devices 101 and 102 are assumed to be reference tags. The wireless devices 101 and 102 may be fixed in their positions by being attached to floors, pillars, shelves, etc. in the areas 131 and 132, respectively. Also, the information recorded inside the wireless devices 101 and 102 is acquired by the RFID reader by performing a detection operation in the vicinity of the RFID reader. The detection operation is performed, for example, by the RFID reader receiving a radio signal transmitted from the RFID tag (by the RFID reader emitting radio waves in the case of a passive RFID tag). In this operation, the RFID reader acquires the tag ID, etc. included in the radio signal.

[0012] The item tag is, for example, attached to a portable item, and its position changes when the item is carried by a user, etc. When the item tag is attached to an item to be managed, item management information for managing the item may be written in advance as other information in a memory built into the item tag. In this embodiment, the wireless device 103 is an item tag.

[0013] The communication device 110 detects a wireless device 100 present in the vicinity, associates information acquired from the detected wireless device 100 with position information of the wireless device 100, and notifies the information processing device 120. The communication device 110 may be, for example, a dedicated device specialized for the purpose of managing goods, or may be a general-purpose device such as a personal computer (PC) or a smartphone. In this embodiment, the communication device 110 has a function for operating as an RFID reader. The RFID reader is, for example, a device that radiates radio waves such as UHF bands to a passive RFID tag and acquires information recorded in the RFID tag from a signal transmitted by the RFID tag in response to the radio waves. Note that, when the RFID tag is an active type, the RFID reader may acquire information recorded in the RFID tag using a signal transmitted autonomously by the RFID tag without radiating radio waves to the RFID tag. The communication device 110 performs a detection operation for detecting an RFID tag, which is a wireless device 100, for example, periodically or in response to a trigger such as a user operation. The communication device 110 may communicate with the wireless device 100 using other communication standards such as NFC. When the communication device 110 detects a reference tag, the communication device 110 identifies the location information of the communication device 110, for example, by using the location information of the reference tag. When the communication device 110 detects an item tag, the location information of the communication device 110 may be used to identify the location information of the item tag. On the other hand, when the communication device 110 detects an item tag as the wireless device 100, the communication device 110 links information such as a tag ID acquired from the item tag with the location information of the item tag and notifies the information processing device 120 of the information.

[0014] Also, the communication device 110 performs measurements and communication to estimate the position of the wireless device 100. In this embodiment, as an example, the communication device 110 estimates the position of the wireless device 100 by performing processing in cooperation with other communication devices. For example, in the position management system of FIG. 1, the communication device 111 measures the distance A between the wireless device 103 and the communication device 111. As an example, the communication device 112 performs measurements to identify the distance B between the wireless device 103 and the communication device 112. The communication devices 111 and 112 can identify the distance A and the distance B by, for example, exchanging the measurement results. Also, as an example, the communication devices 111 and 112 obtain location information to identify each other's locations. As a result, the communication devices 111 and 112 can estimate the position of the wireless device 103 using the distance A and the distance B and the respective location information of the communication devices 111 and 112, etc. The location of the wireless device 103 may be estimated by the information processing device 120. In this case, the communication device 110 may provide the information processing device 120 with a part or all of the information required for the information processing device 120 to estimate the location of the wireless device 103. An example of the configuration of the communication device 110 will be described in further detail later.

[0015] The information processing device 120 is an information processing device that acquires the position of the wireless device 100 and records it in a database. The information processing device 120 may be implemented as an application server, a database server, or a cloud server using a general-purpose computer, for example. The functions of the information processing device 120 may be provided by a single device, or may be provided by multiple physically separate devices working together. In addition, the information processing device 120 may have a database, or a device separate from the information processing device 120 may have a part or all of the database. The information processing device 120 records information such as a tag ID and position information of the wireless device 100 received from the communication device 110 in a database. The information processing device 120 may estimate the position of the wireless device 100 using information for identifying the position of the wireless device 100 acquired from the communication device 110. The communication device 110 and the information processing device 120 are connected, for example, via at least one of a wireless line and a wired line (not shown). The wireless line is, for example, a communication line using a predetermined wireless communication standard such as a wireless LAN (Wi-Fi) communication standard or a cellular communication standard. The wired line is a communication line that uses a predetermined wired communication standard such as Ethernet. An example of the configuration of the information processing device 120 will be described in further detail later.

[0016] In a location management system that uses an RFID reader and an RFID tag to manage items, the RFID reader carried by the user reads a reference tag at the destination of the user's movement, thereby acquiring location information of the RFID reader. In a conventional location management system, when an RFID reader reads an item tag, the information acquired from the item tag and the location information of the RFID reader at that time are linked to each other and recorded. In other words, the location of the RFID reader when the item tag is detected is recorded as the location of the item tag. In such a location management system, the RFID reader that can move over a wide range reads all RFID tags without missing any, thereby managing the locations of item tags that exist over a wide range. In such a location management system, for example, a plurality of RFID readers work together to read RFID tags, thereby improving the RFID tag reading rate.

[0017] However, as described above, in conventional RFID systems, the location information associated with an item tag is the location information of the RFID reader, and the difference in location between the RFID reader and the RFID tag is not taken into consideration. Therefore, even if an item tag is detected by an RFID reader, if the RFID tag to be managed is located far away from the RFID reader, the error between the actual location of the RFID tag and the location information managed by the system may be large. As a result, for example, when a user of the system actually searches for an item, the user may not be able to find the item in the expected location.

[0018] In this embodiment, a technique is provided for improving the accuracy of item location information by estimating the location of an RFID tag based on information obtained by RFID readers operating in cooperation with each other.

[0019] (Example of communication device configuration) FIG. 2 shows an example of a functional configuration of the communication device 110. The communication device 110 includes, for example, a first communication unit 201, a first measurement unit 202, a second communication unit 203, a second measurement unit 204, and a calculation unit 210 as its functions. The calculation unit 210 also includes a control unit 205, a distance determination unit 206, a position estimation unit 207, and a storage unit 208. The communication device 110 may have a communication unit (not shown) for communicating with the information processing device 120. The configuration of FIG. 2 is merely an example, and some or all of the functional units may be replaced with other functional units that perform similar functions, some functional units may be omitted, and further functional units may be added. Also, one functional unit described below may be divided into multiple functional units, and multiple functional units may be integrated into one functional unit. When the communication device 110 performs a predetermined process in cooperation with another communication device, the communication device 110 may operate as a control device or as a controlled device. When the communication device 110 operates as a control device, the communication device 110 requests the other communication device 110 operating as a controlled device to perform a predetermined process. On the other hand, when the communication device 110 operates as a controlled device, the communication device 110 performs a predetermined process in response to a request from the other communication device 110 operating as a control device. Note that the functional configuration of the communication device 110 may be the same whether the communication device 110 operates as a control device or as a controlled device. In the following, the operation of each functional unit in each communication device 110 will be individually described for the cases where the communication device 111 operates as a control device and the communication device 112 operates as a controlled device.

[0020] (When the communication device 111 operates as a control execution device) The first communication unit 201 communicates with the wireless device 100 and acquires information recorded in the wireless device 100. For example, the first communication unit 201 operates as an RFID reader that reads information recorded in an RFID tag by RFID communication. The first communication unit 201 may communicate with the wireless device 100 according to other communication standards such as NFC. When the first communication unit 201 operates as an RFID reader, the first communication unit 201 acquires information such as a tag ID from an RFID tag present within a range of the radio waves emitted by the first communication unit 201. As an example, the first communication unit 201 transmits, for example, a modulated UHF band signal via an antenna in accordance with an instruction from the control unit 205. The first communication unit 201 may transmit a signal autonomously regardless of the presence or absence of an instruction from the control unit 205. This signal may include an instruction (command) for the RFID tag. When the first communication unit 201 receives a signal transmitted from an RFID tag in response to the transmitted signal, the first communication unit 201 extracts a desired signal from the received signal, for example, by canceling the carrier component of the signal transmitted by the first communication unit 201. Note that the method of extracting the desired signal from the received signal is not limited to this method. The first communication unit 201 obtains information such as the tag ID of the RFID tag that transmitted the signal by decoding the extracted signal. The first communication unit 201 notifies the control unit 205 of the obtained information such as the tag ID. In the following, a signal transmitted by a wireless device is referred to as a first signal, and when the wireless device is a passive RFID tag, a signal transmitted by the first communication unit 201 to cause the wireless device to transmit the first signal is referred to as a second signal. Note that when the wireless device is an active RFID tag, the wireless device can transmit the first signal without receiving the second signal from the first communication unit 201.

[0021] The first measurement unit 202 performs measurement to identify the distance between the communication apparatus 111 and the wireless device 100 (for example, distance A in FIG. 1). For example, the first measurement unit 202 measures the strength (signal reception strength) of the first signal received from the wireless device 100, the arrival time (signal arrival time) of the first signal, and the like. When the first measurement unit 202 measures the signal arrival time, for example, the first measurement unit 202 may measure the time from when the first communication unit 201 transmits the second signal to when the first measurement unit 202 receives the first signal transmitted from the wireless device 100. When the transmission time when the wireless device 100 transmits the response signal is known in advance, the communication apparatus 111 may measure the time from when the wireless device 100 transmits the first signal to when the first measurement unit 202 of the communication apparatus 111 receives the first signal. For example, when the wireless device 100 is an active RFID tag that transmits a first signal at a predetermined time, the predetermined time may be treated as the transmission time. Also, even if the first signal transmitted by the wireless device 100 includes information indicating the transmission time, the communication device 111 can identify the transmission time of the first signal in the wireless device 100. Also, when the first measurement unit 202 measures the signal reception strength, for example, the amplitude value or the reception power of the first signal transmitted from the wireless device 100 is measured. Note that the first measurement unit 202 may measure the difference between the strength of the second signal transmitted by the first communication unit 201 and the strength of the first signal received. Also, when the transmission power or the like of the first signal transmitted from the wireless device 100 is known, the first measurement unit 202 may measure the difference between the transmission power and the strength of the signal received by the first measurement unit 202. The first measurement unit 202 notifies the control unit 205 of the measurement results, such as the signal reception strength and the signal arrival time. The measurement results may be recorded in the storage unit 208. The first measurement unit 202 may measure both the signal reception strength and the signal arrival time, or may measure only one of them. It should be noted that the measurement for determining the distance A is not limited to the measurement of the signal reception strength or the signal arrival time.

[0022] The second communication unit 203 communicates with another communication device 110. For example, the second communication unit 203 of the communication device 111 communicates with the communication device 112 to notify the communication device 112 of a request when the communication device 111 cooperates with the communication device 112 to perform a predetermined process. The second communication unit 203 may communicate with the communication device 112 using a communication method different from that of the first communication unit 201. For example, the second communication unit 203 communicates using a communication method according to a standard in which a distance measurement function is defined, such as Ultra Wide Band (UWB) or Bluetooth (registered trademark) standard. Note that the second communication unit 203 may communicate using a method other than the UWB or Bluetooth standard, and may use, for example, a combination of a communication method according to a standard in which a distance measurement function is not defined and a distance measurement method independent of this communication method. Examples of standards related to UWB include wireless USB, wireless 1394, WiNET, and IEEE802.15.4 standards. In this embodiment, the second communication unit 203 uses UWB. For example, the second communication unit 203 of either the communication device 111 or 112 may operate as a coordinator of the IEEE802.15.4 standard to establish a connection. In this case, a connection is established between the second communication units 203 of the communication devices 111 and 112 by performing network detection and association by active scanning or passive scanning. Note that the method of establishing a connection between the communication devices 111 and 112 is not limited to this.

[0023] The second measurement unit 204 performs measurement to specify the distance C between the communication device 111 and the communication device 112. For example, when the second communication unit 203 communicates with the communication device 112 using UWB, the second measurement unit 204 may measure the distance C using a function defined in a standard such as SS-TWR or DS-TWR. Note that SS-TWR and DS-TWR are abbreviations for Single-Sided Two-Way Ranging and Double-Sided Two-Way Ranging, respectively. In addition, the method by which the second measurement unit 204 measures the distance C is not limited to these methods, and the signal reception strength of a signal received from the communication device 112 may be used, as in the first measurement unit 202. In general, when measuring the distance between devices using SS-TWR, it is necessary that the time is synchronized between the devices. In this embodiment, for example, each of the communication device 111 and the communication device 112 may perform time synchronization with an NTP server (not shown) on the network via the base station 400, thereby performing time synchronization between the devices. Note that NTP is an abbreviation for Network Time Protocol. The communication devices 111 and 112 may perform time synchronization for other purposes or methods. The second measurement unit 204 may measure the signal reception strength to identify the distance C. For example, when the second communication unit 203 communicates using Bluetooth, the second measurement unit 204 may measure the signal reception strength of a Bluetooth Low Energy (BLE) beacon transmitted from the communication device 112. The second measurement unit 204 notifies the control unit 205 of the measurement result. The measurement result may be recorded in the storage unit 208.

[0024] As described above, the calculation unit 210 includes the control unit 205, the distance determination unit 206, the position estimation unit 207, and the storage unit 208, and executes various calculations for the operation of the communication device 110. The control unit 205 controls each functional unit of the communication device 111 according to a signal input from each functional unit of the communication device 111 and a control program recorded in the storage unit 208. The distance determination unit 206 performs a process for determining the distance between the wireless device 100 and another communication device based on, for example, the measurement results by the first measurement unit 202 and the second measurement unit 204. The distance determination unit 206 performs a predetermined calculation on, for example, the measurement results by the first measurement unit 202 and the second measurement unit 204 to determine the corresponding distance. In addition, the distance determination unit 206 may hold, for example, a lookup table, and determine the value of the distance corresponding to the measurement results by the first measurement unit 202 and the second measurement unit 204 by referring to the table. The position estimation unit 207 estimates the position of the wireless device 100 based on, for example, the distance specified by the distance specification unit 206, the position of the communication device 110 itself stored in the storage unit 208, and the positions of other communication devices received via the second communication unit 203. Note that, if the estimation of the position of the wireless device 100 is not performed by the communication device 110, the position estimation unit 207 may be omitted. The storage unit 208 stores various information such as a control program, the measurement results of the first measurement unit 202 and the second measurement unit 204, and information acquired via the first communication unit 201 and the second communication unit 203. The functions of these in the calculation unit 210 will be described in detail below.

[0025] For example, the control unit 205 issues a detection instruction to the first communication unit 201 to detect the wireless device 100 present around the communication apparatus 111. The control unit 205 may issue a detection instruction periodically, or may issue a detection instruction to the first communication unit 201 when instructing the first measurement unit 202 to perform measurement using a signal from the wireless device 100. When the control unit 205 receives information such as a tag ID as a response to the detection instruction to the first communication unit 201, the control unit 205 determines the type of the RFID tag that is the sender of the tag ID. As an example, when the control unit 205 acquires information that can determine the type of the RFID tag together with the tag ID, the control unit 205 may determine the type of the RFID tag based on this information. In addition, the control unit 205 may make an inquiry to the information processing device 120 to determine the type of the RFID tag.

[0026] When the transmission source of the acquired information is the reference tag, the control unit 205 specifies the position of the communication device 111 based on the acquired information. For example, when the position information of the reference tag is recorded in the memory of the reference tag and the control unit 205 receives the position information of the reference tag together with the tag ID, the control unit 205 specifies the position information as the position of the communication device 111. The control unit 205 may also make an inquiry to the information processing device 120 using the acquired tag ID, acquire the position information of the reference tag associated with the tag ID and registered in the database, and specify the position information as the position of the communication device 111. The control unit 205 records the specified position information of the communication device 111 in the storage unit 208. The control unit 205 may also link the specified position information of the communication device 111 with the device ID of the communication device 111 and notify the information processing device 120. The device ID is an identifier that identifies each of the communication devices 110.

[0027] The control unit 205 may use a self-location estimation technique also called PDR to measure the relative movement amount of the communication device 111 in addition to the location information acquired from the reference tag, to identify the location of the communication device 111. PDR is an abbreviation for Pedestrian Dead Reckoning. The control unit 205 may have a sensor for measuring the relative movement amount. An example of a combination of sensors for measuring the relative movement amount is a three-axis acceleration sensor, a gyro sensor, and a geomagnetic sensor. The three-axis acceleration sensor measures the acceleration applied to the communication device 111 in a device coordinate system unique to the communication device 111. The gyro sensor measures the angular velocity based on the change in the attitude of the communication device 111. The geomagnetic sensor measures the orientation of the communication device 111 in the real space. The control unit 205 can measure the relative movement amount of the communication device 111 by accumulating the acceleration while converting the direction of the acceleration of the communication device 111 into a direction in the coordinate system of the real space based on the measurement results of each sensor. It should be noted that the method by which the control unit 205 measures the relative movement amount is not limited to this measurement method.

[0028] When the transmission source of the acquired information is an item tag, the control unit 205 associates the acquired tag ID, item management information, etc. with the location information of the item tag and notifies the information processing device 120. The location information of the item tag may use the location information of the communication device 111 recorded in the storage unit 208, or may use the location information of the item tag estimated by the location estimation unit 207. When using the location information of the item tag estimated by the location estimation unit 207 as the location information of the item tag, the control unit 205 requests the communication device 112 to perform a predetermined operation. As an example, the predetermined operation includes the communication device 112 receiving a first signal transmitted by the wireless device 100 and measuring the signal reception strength, signal arrival time, etc. using the first signal. The predetermined operation also includes notifying the communication device 111 of the measurement result measured by the communication device 112 using the first signal. The control unit 205 causes the distance determination unit 206 to determine the distance B between the communication device 112 and the wireless device 100 using the measurement result by the communication device 112.

[0029] 3 shows an example of a sequence in which the communication device 112 performs measurement based on a request from the communication device 111. First, the communication device 111 transmits a beacon request in each frequency channel (F301). When the communication device 112 receives the beacon request, it transmits a beacon (F302). When the communication device 111 receives the beacon, it transmits a connection request to the communication device 112 (F303). When the communication device 112 receives the connection request, it transmits a connection response (F304). When the communication device 111 receives the connection response, a connection with the communication device 112 is established. When the connection with the communication device 112 is established, the communication device 111 transmits a reception request to the communication device 112 (F305). The reception request is a signal that requests the communication device 112 to receive a first signal transmitted by the wireless device 103 and measure the signal reception strength, the signal arrival time, or the like using the first signal. The reception request may include information such as a period and frequency during which the communication device 112 should perform measurement using the first signal, and a tag ID and a command included in a response signal to be received. The period during which the communication device 112 should perform measurement using the first signal may include a time during which the first signal is expected to be received. When the communication device 112 receives the reception request, the communication device 112 determines whether or not to perform processing included in the reception request, and transmits a response including the determination result (F306). By receiving this response from the communication device 112, the communication device 111 can confirm that the communication device 112 receives and measures the first signal. Note that the communications from F301 to F306 are performed using, for example, the second communication unit 203 of each of the communication devices 111 and 112. Here, in this embodiment, the communication devices 111 and 112 use UWB as the second communication unit 203.

[0030] Thereafter, the communication device 111 transmits a second signal to the wireless device 103 to cause the wireless device 103 to transmit the first signal (F307). This second signal is transmitted, for example, via the first communication unit 201 of the communication device 111. When the wireless device 103 receives the second signal, it transmits a first signal in response to the second signal (F308). The first signal is received via the first communication unit 201 in each of the communication device 111 and the communication device 112.

[0031] In the communication device 112, the first communication unit 201 extracts the tag ID from the received first signal and notifies the control unit 205. In addition, in the communication device 112, the first measurement unit 202 measures the signal reception strength and the signal arrival time using the received first signal and notifies the control unit 205. The control unit 205 of the communication device 112 records the acquired tag ID and the measurement result in association with each other in the storage unit 208. Note that, if the acquired tag ID is different from the tag ID specified in the reception request received from the communication device 111 in F305, the communication device 112 may discard this tag ID and the measurement result. On the other hand, the communication device 111 transmits a measurement result request to the communication device 112 (F309). The measurement result request is a signal requesting notification of the tag ID included in the received first signal and the result of the measurement performed by the communication device 112 using the first signal. When the communication device 112 receives the measurement result request, it transmits the tag ID extracted from the first signal from the wireless device 103 and the measurement result of the first signal to the communication device 111 (F310). If the acquired tag ID is different from the tag ID specified in the measurement result request from the communication device 111, the communication device 112 may delete the tag ID and the measurement result stored in the storage unit 208. Through the above procedure, the communication device 111 can acquire information for identifying the distance B between the communication device 112 and the wireless device 100 from the communication device 112. Note that the procedure for the communication device 112 to receive the first signal transmitted by the wireless device 103 in response to the second signal transmitted by the communication device 111 to the wireless device 103 and perform measurement for identifying the distance B is not limited to the above.

[0032] Furthermore, the communication device 111 acquires the location information of the communication device 112 in order to estimate the location information of the wireless device 103. For example, the communication device 111 requests the communication device 112 to notify the location information of the communication device 112. This request is transmitted and received, for example, using the second communication units 203 of the communication device 111 and the communication device 112. Furthermore, the communication device 111 may acquire the location information of the communication device 112 by inquiring of the information processing device 120. In the communication device 111, the acquired location information of the communication device 112 is notified to the location estimation unit 207. Furthermore, in the communication device 111, the location information of the communication device 112 may be stored in the storage unit 208.

[0033] The communication device 111 may only use communication devices whose distance C between the communication device 111 and the wireless device 103 is equal to or less than a threshold as a partner for performing processing in cooperation with the communication device. For example, the communication device 111 may estimate the position of the wireless device 103 by cooperating with other communication devices that exist in the vicinity of the communication device 111 and are assumed to have a close communication environment with the wireless device 103. The other communication devices 110 detected by the communication device 111 are not necessarily capable of receiving the first signal from the wireless device 103. For this reason, the communication device 111 can avoid unnecessarily attempting to cooperate with communication devices that cannot receive the signal of the wireless device 103 by cooperating only with communication devices that exist in the vicinity of the communication device 111. The control unit 205 may use the second communication unit 203 to specify the distance C between the communication devices 111 and 112 in order to specify the distance between the communication devices. The control unit 205 may specify the distance C based on the position information of each of the communication devices 111 and 112. When the second communication unit 203 uses UWB, the distance C can be determined with higher accuracy by determining the distance C using UWB compared to determining the distance C using the respective position information determined based on the received signal from the reference tag. Therefore, when the control unit 205 determines a cooperation partner to perform processing in cooperation with the devices based on the distance between the devices, the cooperation partner can be determined with higher accuracy.

[0034] The control unit 205 can notify the information processing device 120 of information on the detected wireless device 100, etc. For example, when the control unit 205 of the communication device 110 detects a reference tag, it links the position information of its own device specified using the reference tag with the device ID of its own device and notifies the information processing device 120 of the same. Note that the control unit 205 of the communication device 110 may notify the information processing device 120 of the tag ID of the reference tag as information for specifying the position information of its own device, and the information processing device 120 may specify the position information of the communication device 110 using the tag ID of the notified reference tag. When the control unit 205 detects an item tag, it links the position information of the item tag estimated by the position estimation unit 207 to information such as the tag ID of the detected item tag and notifies the information processing device 120 of the same. The control unit 205 may notify the information processing device 120 of the location information of the communication device 111, the distance A between the communication device 111 and the wireless device 103, the distance B between the communication device 112 and the wireless device 103, and the distance C between the communication devices 111 and 102. The information processing device 120 may estimate the location of the item tag based on the information notified to the control unit 205.

[0035] Distance determination unit 206 determines distance A between communication apparatus 111 and wireless device 103 and distance B between communication apparatus 112 and wireless device 103. As an example, distance determination unit 206 determines distance A using the signal reception strength or signal arrival time measured by first measurement unit 202. Distance determination unit 206 may determine distance A using either the signal reception strength or the signal arrival time measured by first measurement unit 202, may determine distance A using both of them, or may determine distance A using information other than them.

[0036] FIG. 4(A) shows an example of a method in which the distance determination unit 206 determines the distance A using the signal arrival time measured by the first measurement unit 202. The distance determination unit 206 determines the distance A using the time it takes for the first measurement unit 202 to receive the first signal from the wireless device 103 in response to the second signal, starting from the time when the first communication unit 201 transmits the second signal. As an example, the transmission time when the first communication unit 201 transmits the second signal is set to t=T400, and the reception time when the first measurement unit 202 receives the response signal is set to t=T401. At this time, the time ΔT1 that the radio wave takes to travel the distance A between the communication device 111 and the wireless device 103 is ΔT1=T401-T400. Therefore, the distance A is determined as c×ΔT1 / 2. Here, c is the propagation speed of the radio wave. If a processing time Tp occurs between when the wireless device 103 receives the first signal and when it transmits a response signal, the distance determination unit 206 may determine the distance A, excluding this processing time, as A=c×(ΔT1-Tp) / 2. Note that the example in FIG. 4A illustrates a case in which the wireless device 103 is a passive RFID tag. If the wireless device 103 is an active RFID tag, for example, the distance A can be determined as A=c×(T401-T410), where T410 is the timing when the wireless device 103 transmits the first signal.

[0037] Further, the distance determination unit 206 can determine the distance B using the signal travel time measured by the first measurement unit 202 of the communication device 112. FIG. 4B shows, as an example, a method in which the distance determination unit 206 determines the distance B using the signal travel time measured by the first measurement unit 202 of the communication device 112. The distance determination unit 206 determines the distance B using the time it takes for the first signal from the wireless device 103 in response to the second signal to be received by the communication unit 201 of the first communication device 112, starting from the time when the first communication unit 201 transmits the second signal. The transmission time when the first communication unit 201 transmits the second signal is t=T400, and the reception time when the first measurement unit 202 of the communication device 112 receives the second signal is t=T402. At this time, the time ΔT2 taken for the radio wave to propagate the distance A between the communication device 111 and the wireless device 103 and the distance B between the communication device 111 and the wireless device 103 is ΔT2=(T402-T400), and the distance is c×ΔT2. Here, since the distance A=c×ΔT1 / 2, the distance B is specified as c×(ΔT2-ΔT1 / 2). Note that, if a processing time occurs from when the first signal is received by the wireless device 100 until the response signal is transmitted, the distance B may be calculated excluding this processing time. That is, when the processing time is Tp, the sum of the distance A and the distance B is c×(ΔT2-Tp), while the distance A is A=c×(ΔT1-Tp) / 2 as described above, so the distance B can be calculated as B=c×(ΔT2-ΔT1 / 2-Tp / 2).

[0038] When the distance A is specified using the signal reception strength, the distance specifying unit 206 specifies the distance A based on, for example, a propagation loss until the signal transmitted from the antenna of the wireless device 103 is received by the first measurement unit 202. As an example, the distance specifying unit 206 may have, as a correspondence table, a result of measuring in advance the signal reception strength at the communication device 110 when the wireless device 100 transmits a signal while changing the distance between the communication device 110 and the wireless device 100. In this case, the distance specifying unit 206 may specify the distance A by comparing the actual signal reception strength of the first signal with the correspondence table. In addition, the distance specifying unit 206 can similarly specify the distance B using the signal reception strength measured by the first measurement unit 202 of the communication device 112. Note that in this case, the distance specifying unit 206 may use, for example, a result of one of the communication devices 110 transmitting a second signal and the other measuring the signal reception strength of the first signal while changing the distance between the wireless device 100 and the two communication devices 110 as the correspondence table. In this case, the distance determination unit 206 may determine the distance B by comparing the actual signal reception strength of the first signal with the correspondence table. Alternatively, the distance determination unit 206 may calculate the distance A or distance B from the signal reception strength, assuming that radio waves propagate between the communication apparatus 110 and the wireless device 100 using free space propagation or another propagation model. Such calculations may be performed when the signal transmission power in the wireless device 100 is constant or when the signal transmission power can be determined.

[0039] The position estimation unit 207 estimates the position of the wireless device 100. As an example, the position estimation unit 207 estimates the position of the wireless device 103 by a multipoint positioning method using one or more of the distances A and B, the position information of the communication device 111, and the position information of the communication device 112. FIG. 5(A) shows an example of a method for estimating the position of the wireless device 103 using the distances A and B and the respective position information of the communication device 111 and the communication device 112. The position estimation unit 207 creates a circle 501 with the position of the communication device 111 as its center and the distance A as its radius. The position estimation unit 207 creates a circle 502 with the position of the communication device 112 as its center and the distance B as its radius. The position estimation unit 207 identifies two intersections 503 and 504 of these two circles. Then, the position estimation unit 207 identifies a position where an item may actually be present among the intersections of the two circles. For example, when one of the two identified intersections, 503, indicates a position inside a building where an item is managed, and the other intersection, 504, indicates a position outside the building, the intersection 503 indicating the position inside the building is estimated as the position of the wireless device 103. The position estimation unit 207 notifies the control unit 205 of the estimated position of the wireless device 103. The position estimation unit 207 may correct the position information of the communication device 112 using the distance C between the communication device 111 and the communication device 112 estimated by the second measurement unit 204, and estimate the position of the wireless device 103 using the corrected position information. As an example, the position estimation unit 207 calculates the distance C' between the devices using the respective position information of the communication devices 111 and 112. The position estimation unit 207 sets the position coordinates of the distance C' from the position coordinates of the communication device 111 to the position coordinates of the communication device 112 after correction on the vector from the position coordinates of the communication device 111 to the position coordinates of the communication device 112. The position estimation unit 207 may use the corrected position coordinates of the communication device 112 when creating a circle 502 with the position of the communication device 112 as the center and the distance B as the radius. By generating the position information of the communication device 112 using the distance to the communication device 112 measured by a method capable of highly accurate positioning such as UWB, based on the position information of the communication device 111, the accuracy of the position estimation of the wireless device 103 can be improved.In addition, the position estimation unit 207 may determine whether to use the measurement result by the communication device 112 using the distance C specified by the distance determination unit 206 and the distance C' calculated from the position information of each of the communication devices 111 and 112. As an example, when the difference between the distance C and the distance C' is smaller than a threshold, the position estimation unit 207 determines to use the measurement result by the communication device 112. Alternatively, when the difference between the distance C and the distance C' is larger than a threshold, the position estimation unit 207 determines not to use the measurement result by the communication device 112. When the distance between the communication devices 110 measured by UWB or the like and the distance between the devices calculated using the respective position information are large, there is a possibility that the error in the position information of one of the communication devices 110 is large. By avoiding the use of the information of the communication device 112 in such a positional relationship, it is possible to avoid a large error when estimating the position information of the wireless device 100. Note that, for example, like communication device 112, communication device 111 can determine whether to use information of other communication devices based on the difference between the distance between communication devices determined by distance determination unit 206 and the distance based on the location information. Furthermore, when communication device 111 determines not to use information of more than a predetermined number of other communication devices, communication device 111 may not estimate the location of wireless device 103. This is because when the distance between communication device 111 and many other communication devices is inaccurate, it is assumed that the location of communication device 111 itself is inaccurate.

[0040] Also, the method by which the position estimation unit 207 estimates the position of the wireless device 100 is not limited to the above method. For example, the position of the wireless device 100 may be estimated using three communication devices 110. FIG. 5(B) shows an example of a method of estimating the position of the wireless device 100 using three communication devices 110. In this embodiment, in addition to the method of estimating the position of the wireless device 100 using the above two communication devices, the position information of the communication device 113 and the distance D between the communication device 113 and the wireless device 103 are used. In addition to the above-mentioned circle 501 and circle 502, the position estimation unit 207 creates a circle 505 with the position of the communication device 113 as its center and the distance D as its radius. Then, the position estimation unit 207 estimates the intersection 506 of these three circles as the position of the wireless device 103. The position estimation unit 207 notifies the control unit 205 of the estimated position of the wireless device 103. Note that the position estimation unit 207 may record the estimated position of the wireless device 103 in the storage unit 208.

[0041] The storage unit 208 stores a control program executed by the control unit 205, position information of the communication device 111, etc. The storage unit 208 may store information such as the tag ID of the RFID tag detected by the first communication unit 201, position information of the communication devices 111 and 112, distances A and B specified by the distance specifying unit 206, the device ID of the communication device 111, etc. The storage unit 208 may store the measurement result of the first measurement unit 202, the measurement result of the second measurement unit 204, position information of the wireless device estimated by the position estimation unit 207, etc.

[0042] (When the communication device 112 operates as a controlled device) The first communication unit 201 receives the first signal transmitted from the wireless device 100 in response to the second signal transmitted by the first communication unit 201 of the communication apparatus 111 according to an instruction from the control unit 205, and acquires information recorded in the wireless device 100. As an example, when the first communication unit 201 detects the second signal transmitted by the first communication unit 201, the first communication unit 201 extracts a desired signal by canceling the carrier component of the second signal from the first signal received thereafter. The first communication unit 201 acquires information such as the tag ID of the wireless device 100 that transmitted the first signal by decoding the extracted signal. Note that the method of extracting the desired signal from the received signal is not limited to this method. The first communication unit 201 notifies the control unit 205 of the acquired information such as the tag ID.

[0043] The first measurement unit 202 performs measurement to identify the distance between the communication apparatus 112 and the wireless device 100 (for example, distance B in FIG. 1) according to an instruction from the control unit 205. For example, the first measurement unit 202 measures the signal reception strength and signal arrival time of the first signal transmitted from the wireless device 100 in response to the second signal transmitted by the first communication unit 201 of the communication apparatus 111. When measuring the signal arrival time, the first measurement unit 202 may measure, for example, the time from when the second signal is transmitted by the first communication unit 201 of the communication apparatus 111 to when the second signal transmitted from the wireless device 100 is received by the first measurement unit 202. When the transmission time at which the wireless device 100 transmits the first signal is known in advance, the first measurement unit 202 may measure the time from this transmission time to when the first measurement unit 202 receives the first signal. The first measurement unit 202 may measure only the reception time at which the first signal is received. The first measurement unit 202 notifies the control unit 205 of the measurement results, such as the signal reception strength and the signal arrival time. The measurement results may be recorded in the storage unit 208. Note that the measurement for identifying the distance B is not limited to the measurement of the signal reception strength and the signal arrival time. The first measurement unit 202 may measure both the signal reception strength and the signal arrival time, or may measure only one of them.

[0044] The second communication unit 203 communicates with the communication device 111 in order to perform cooperative processing between the communication device 111 and the device. The operation of the second communication unit 203 is similar to that of the second communication unit 203. For example, the second communication unit 203 establishes a connection using the same communication method as the second communication unit 203 of the communication device 111 according to the sequence example shown in Fig. 3, receives a reception request and a measurement result request from the communication device 111, and transmits a response to the reception request and the measurement result.

[0045] The second measurement unit 204 performs measurement to identify the distance C between the communication device 111 and the communication device 112. For example, the second measurement unit 204 is paired with the second measurement unit 204 and measures the distance C using SS-TWR, DS-TWR, or the like.

[0046] The control unit 205 performs processing according to a request received from the communication device 111 during cooperation processing between devices. For example, if the request from the communication device 111 is to receive a first signal transmitted by the wireless device 100, the control unit 205 instructs the first communication unit 201 to receive the first signal. Also, if the request from the communication device 111 is to perform measurement using the first signal transmitted by the wireless device 100, the control unit 205 instructs the first measurement unit 202 to perform measurement using the first signal. Note that, if the request received from the communication device 111 includes information on a period or frequency for performing measurement using the first signal, the control unit 205 may instruct the first measurement unit 202 by specifying the period or frequency.

[0047] The control unit 205 associates information such as the tag ID acquired from the first communication unit 201 with the measurement result acquired from the first measurement unit 202 and records them in the storage unit 208. If the acquired tag ID is different from the tag ID notified in the request received from the communication device 111, the control unit 205 may discard the acquired tag ID and the measurement result. Furthermore, if the request from the communication device 111 is to notify the communication device 111 of the result measured by the communication device 112, the control unit 205 transmits the tag ID and the measurement result recorded in the storage unit 208 to the communication device 111. Furthermore, when the control unit 205 receives a request from the communication device 111 to transmit the position information of the communication device 112, for example, the control unit 205 transmits the position information of the communication device 112 stored in the storage unit 208 to the communication device 111 using the second communication unit 203.

[0048] The distance determining unit 206, the position estimating unit 207, and the storage unit 208 of the communication device 112 operate in the same manner as the distance determining unit 206, the position estimating unit 207, and the storage unit 208 of the communication device 111, respectively.

[0049] 6 shows an example of a hardware configuration of the communication device 110 according to this embodiment. As an example of the hardware configuration, the communication device 110 has, for example, a storage unit 601, a control unit 602, a function unit 603, an input unit 604, an output unit 605, a communication unit 606, and an antenna 607. The communication device 110 may have multiple antennas.

[0050] The storage unit 601 is configured with one or more memories including ROM, RAM, etc., and may store various information such as control programs for each functional unit constituting the communication device 110 to perform various operations, and parameters for communication of the communication device 110. ROM and RAM are abbreviations for Read Only Memory and Random Access Memory, respectively. The storage unit 601 may be configured to include storage media such as a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a magnetic tape, a non-volatile memory card, and a DVD, in addition to memories such as ROM and RAM.

[0051] The control unit 602 is configured with one or more processors including, for example, a CPU, an MPU, etc., and controls the entire communication device 110 by executing a control program stored in the storage unit 601. The control unit 602 may control the entire communication device 110 in cooperation with the control program stored in the storage unit 601 and an OS (Operating System). The CPU and MPU are abbreviations for Central Processing Unit and Micro Processing Unit, respectively. When the control unit 602 has multiple processors that can be implemented by a multi-core or the like, the entire communication device 110 may be configured to be controlled by the multiple processors.

[0052] Furthermore, the control unit 602 controls the function unit 603 to execute predetermined processes such as measuring distances and estimating position information. The function unit 603 is, for example, hardware that enables the communication device 110 to execute the above-mentioned predetermined processes.

[0053] The input unit 604 receives various operations from the user. The output unit 605 outputs various types of information to the user via a monitor screen or a speaker. The output from the output unit 605 may be a display on a monitor screen, a voice output from a speaker, a vibration output, or the like. The input unit 604 and the output unit 605 may both be implemented as a single module, such as a touch panel display. The input unit 604 and the output unit 605 may be devices integrated with the communication device 110, or may be separate devices.

[0054] The communication unit 606 controls wireless communication conforming to, for example, RFID and UWB standards. The communication unit 606 may also control wireless communication conforming to other wireless communication standards such as Bluetooth. The communication unit 606 transmits and receives signals for wireless communication via the antenna 607 in accordance with an instruction from the control unit 602. The communication unit 606 is a so-called wireless chip, and may itself include one or more processors and memories. The communication device 110 detects information recorded in the wireless device 100 using the communication unit 606, and notifies the information processing device 120 of the information. The communication device 110 also communicates with other communication devices using the communication unit 606. When the method of the communication device 110 detecting information recorded in the wireless device 100 is different from the method of communicating with other communication devices, the communication device 110 may have multiple communication units 606 for executing each method. The communication unit 606 may also measure signal reception strength, signal arrival time, and the like using the received signal. The antenna 607 may be configured separately from the communication unit 606, or may be configured together with the communication unit 606 as a single module.

[0055] The antenna 607 is an antenna capable of communication in, for example, the VHF band, the UHF band, the microwave band (2.4 GHz, 3.4 to 4.8 GHz band), the quasi-millimeter wave band (24.25 to 29 GHz band), and the like. In FIG. 6, the communication device 110 has two antennas 607, but the communication device 110 may have one or three or more antennas, and may have one or more antennas for each frequency band that the device can use. In addition, when the communication device 110 has multiple antennas, the communication device 110 may have a communication unit 606 for each antenna. When the communication device 110 communicates by UWB, it may have a separate antenna for communicating by UWB.

[0056] (Example of configuration of information processing device) 7A shows an example of the functional configuration of the information processing device 120. The information processing device 120 includes, as its functions, a communication unit 701, a database 702, and a management unit 703, for example. The configuration in FIG. 7 is merely an example, and some or all of the functional units may be replaced with other functional units that perform similar functions, some functional units may be omitted, and further functional units may be added. In addition, one functional unit described below may be divided into multiple functional units, and multiple functional units may be integrated into one functional unit.

[0057] The communication unit 701 is a communication interface that communicates with other devices such as the communication device 110. The communication unit 701 may be, for example, a wired communication interface or a wireless communication interface.

[0058] The database 702 stores information for managing the positions of the wireless devices 100 that are targets of management in the position management system of this embodiment. Figures 7(B) to (D) show an item tag management table 710, a reference tag management table 720, and a communication device management table 730 as examples of management tables held by the database 702. The database 702 may include other management tables, and may store information in other representation methods.

[0059] The item tag management table 710 has five data items, namely, a tag ID 711, a type 712, a coordinate 713, an item ID 714, and a name 715. The tag ID 711 is identification information for uniquely identifying each of the wireless devices 100 attached to the managed items, and is the same as the tag ID stored in the memory of each wireless device 100. The type 712 is identification information for identifying the type of the wireless device 100, and indicates, for example, whether each wireless device 100 is a reference tag or an item tag. The coordinate 713 indicates the position coordinate of the wireless device 100. For example, the coordinate 713 is updated when the wireless device 100 is detected by the communication device 110, and the tag ID and the position information stored in the memory of the wireless device 100 are linked and notified to the information processing device 120. For example, Null is recorded as the coordinate 713 of a wireless device with a tag ID of TI2, which indicates that the wireless device has not been detected by the communication device 110. When the wireless device 100 is detected by the communication device 110 and its tag ID and location information are notified to the information processing device 120, the location information is recorded at the coordinates 713. The item ID 714 is an identifier for identifying the item to which the wireless device 100 is attached. The name 715 is the name of this item. The item ID 714 and the name 715 may be determined according to a predetermined rule so that the administrator of the position management system can easily identify the items to be managed. The tag ID 711, type 712, item ID 714, and name 715 of each item tag may be registered in advance in a database by the administrator of the position management system of this embodiment.

[0060] The reference tag management table 720 has four data items: tag ID 721, type 722, coordinates 723, and location 724. The tag ID 721 and type 722 are the same as the tag ID 711 and type 712, respectively. The coordinates 723 indicate the position coordinates where the reference tag is affixed. The location 724 indicates the location where the reference tag is affixed. For example, it is shown that the reference tags with tag IDs TP1 and TP2 are affixed to areas 1 and 2 within a building, respectively. The tag ID 721, type 722, coordinates 723, and location 724 of each reference tag may be registered in advance in the database by an administrator of the location management system of this embodiment.

[0061] The communication device management table 730 has three data items, namely, a device ID 731, a coordinate 732, and an update time 733. The device ID 731 is an identifier for identifying each communication device 110. The device ID 731 is the same as the device ID recorded in the storage unit 208 of the communication device 110. The coordinate 732 indicates the position coordinate of the communication device 110 corresponding to the device ID 731. The coordinate 732 is registered or updated by the communication device 110 linking the position information of the communication device 110 with the device ID and notifying the information processing device 120. The update time 733 indicates the time when the coordinate 732 of the communication device 110 corresponding to the device ID 731 was registered or updated on the communication device management table 730. The device ID 731 may be registered in advance in a database by an administrator of the location management system of this embodiment.

[0062] The management unit 703 is a set of a plurality of software modules for managing data in the database 702. Each software module may be operated by one or more processors (not shown) executing a computer program stored in a memory (not shown). The management unit 703 records, for example, information notified to the information processing device 120 from the communication device 110 or the like via the communication unit 701 in the database 702. For example, when the management unit 703 is notified of the tag ID and position information of an item tag from the communication device 110, the management unit 703 records the notified position information in the coordinates 713 corresponding to the notified tag ID on the item tag management table 710. In addition, the management unit 703 acquires information for responding to the inquiry from the database based on an inquiry received from the communication device 110 or the like via the communication unit 701, and notifies the inquiry source communication device 110 or the like of the information. For example, when the management unit 703 receives an inquiry about location information from the communication device 110 along with the tag ID of a reference tag, the management unit 703 identifies information about coordinates 723 corresponding to the notified tag ID on the reference tag management table 720 and notifies the communication device 110 that originated the inquiry. Also, when the management unit 703 receives an inquiry about location information from the communication device 110 along with the device ID, the management unit 703 identifies coordinates 732 corresponding to the notified device ID on the communication device management table 730 and notifies the communication device 110 that originated the inquiry.

[0063] (Example of a flowchart of a process in a communication device) 8 shows an example of a flowchart of a process performed by the communication device 110 according to the present embodiment to detect the wireless device 100 and estimate its position. This process is performed, for example, when the communication device 110 is turned on and the control unit 205 executes a program stored in the storage unit 208.

[0064] The control unit 205 receives an instruction from a user to start detection of the wireless device 100 (S801). The start of detection of the wireless device 100 may be instructed, for example, by the user performing a predetermined operation on the input unit 604. Note that the control unit 205 may also receive an instruction from the information processing device 120 to start detection of the wireless device 100.

[0065] When an instruction to start detection of the wireless device 100 is received (YES in S801), the control unit 205 determines whether or not to detect the wireless device 100 (S802). For example, in response to receiving an instruction to start detection of the wireless device 100, the control unit 205 determines to detect the wireless device 100 (YES in S802). Here, after the detection process is completed, the control unit 205 may repeat the detection process periodically without receiving an instruction to start detection again. In this case, the control unit 205 determines not to detect the wireless device during a period when detection is not performed (NO in S802). When the control unit 205 determines to detect the wireless device 100 (YES in S802), it executes the detection process of the wireless device 100 (S803). For example, the detection process is executed by the control unit 205 instructing the first communication unit 201 to detect the wireless device 100. The control unit 205 may instruct the first communication unit 201 to autonomously detect the wireless device 100. In this case, the first communication unit 201 periodically detects the wireless device 100 until the first communication unit 201 is instructed by the control unit 205 to stop the operation. On the other hand, when the detection of the wireless device 100 is not executed (NO in S802), the control unit 205 advances the process to S806.

[0066] 9, an example of a flowchart of the process when the control unit 205 detects the wireless device 100 in S803 and obtains information recorded in the wireless device 100 will be described. The control unit 205 starts detecting the wireless device 100 using the first communication unit 201 (S901). When the control unit 205 obtains information such as a tag ID from the first communication unit 201 as a result of the detection of the wireless device 100 (YES in S902), the control unit 205 determines whether the wireless device 100 detected by the first communication unit 201 is a reference tag or an item tag (S903). Note that when the first communication unit 201 does not detect the wireless device 100 (NO in S902), the control unit 205 ends the tag detection process.

[0067] When the wireless device 100 detected by the first communication unit 201 is a reference tag (YES in S903), the control unit 205 acquires the position information of the reference tag, updates the position information of the communication device 110 (S904), and ends this process. Note that when the signal reception strength of the signal received from the reference tag is lower than a threshold, the control unit 205 may not update the position information of the communication device 110. Also, the control unit 205 may notify the information processing device 120 of the updated position information. On the other hand, when the wireless device 100 detected by the first communication unit 201 is an item tag (NO in S903), the control unit 205 links the tag ID, etc. of the item tag with the position information of the item, and transmits it to the information processing device 120, and ends this process.

[0068] Returning to FIG. 8, the description will be continued. The control unit 205 determines whether or not to perform cooperation processing following the detection processing of the wireless device 100 (S804). The control unit 205 performs cooperation processing between communication devices at a predetermined cycle, for example. In this case, the control unit 205 may determine to perform cooperation processing at the timing of performing the cooperation processing, and may determine not to perform cooperation processing at other timings. When the control unit 205 determines to perform cooperation processing because, for example, a predetermined time has elapsed from the time when the previous cooperation processing was performed (YES in S804), the control unit 205 performs cooperation processing with another communication device (S805). For example, the control unit 205 instructs the second communication unit 203 to detect another communication device performing cooperation processing, and performs estimation processing of the position of the wireless device 100 in cooperation with the other detected communication device. On the other hand, when cooperation between communication devices is not to be performed (NO in S804), the control unit 205 advances the process to S806.

[0069] An example of a flowchart of the process when the control unit 205 estimates the position of the wireless device 100 by the cooperation process between the communication devices in S805 will be described with reference to FIG. 10. The control unit 205 judges whether the second communication unit 203 detects another communication device (S1001). If the second communication unit 203 detects another communication device (YES in S1001), the control unit 205 measures the distance C between the other communication device detected by the second communication unit 203 using the second measurement unit 204, and judges whether the distance C is within a threshold (S1002). If the distance C is within the threshold (YES in S1002), the control unit 205 acquires the device ID of the detected communication device, and records the device ID and the distance C of the detected communication device in the storage unit 208 as the detection result (S1003). Note that the control unit 205 may acquire the position information of the detected communication device from the detected communication device. Then, the control unit 205 determines whether the communication device 110 operates as a control device (S1004). For example, when the communication device 110 detects the wireless device 100, the control unit 205 determines that the communication device 110 operates as a control device. Note that the control unit 205 may make this determination based on other conditions, such as determining that the communication device 110 operates as a control device when the communication device 110 is communicating with the wireless device 100. Note that when no other communication device is detected (NO in S1001) or when the distance C between the detected other communication device and the communication device 110 exceeds a threshold value (NO in S1002), the control unit 205 ends the cooperation process between the communication devices.

[0070] When the communication device 110 operates as a control device (YES in S1004), the control unit 205 requests the other communication device to perform cooperation processing between the communication devices (S1011). The control unit 205 may notify the other communication device of information such as a period and frequency for performing measurement, a tag ID and command contents included in a response signal to be received, together with this request. When the control unit 205 receives a response indicating that the request has been accepted from the other communication device (YES in S1012), it transmits a first signal to the wireless device 100 using the first communication unit 201 (S1013). When the control unit 205 does not receive a response indicating that the request has been accepted from the other communication device (NO in S1012), it ends the cooperation processing between the communication devices. However, this is not limited to this, and for example, when a response indicating that the request has been accepted is not received from the other communication device, the control unit 205 may return the processing to S1001 to search for another communication device.

[0071] The control unit 205 receives a first signal from the wireless device 100 using the first communication unit 201, and acquires information such as a tag ID (S1014). The control unit 205 also uses the first measurement unit 202 to measure the signal reception strength and signal arrival time of the first signal from the wireless device 100 (S1015). Furthermore, the control unit 205 uses the second communication unit 203 to request the other communication device to notify the measurement results such as the signal reception strength and signal arrival time of the first signal from the wireless device 100 (S1016). If the measurement results are received from the other communication device (YES in S1017), the control unit 205 causes the position estimation unit 207 to estimate the position of the wireless device 100 based on the received measurement results and the measurement results by the first measurement unit 202 (S1018), and ends the process. If the measurement results are not received from the other communication device (NO in S1017), the control unit 205 ends the cooperation process between the communication devices.

[0072] On the other hand, when the communication device 110 operates as a controlled device (NO in S1004), the control unit 205 judges whether a request to perform cooperation processing between communication devices is received from the control device via the second communication unit 203 (S1005). When the control unit 205 receives a request (YES in S1005), it judges whether to accept this request and transmits a response to the request (S1006). Furthermore, the control unit 205 instructs the first communication unit 201 to receive a first signal transmitted by the wireless device 100, and instructs the first measurement unit 202 to perform measurement using this first signal. Note that when the control unit 205 acquires information such as a period and frequency for performing measurement, a tag ID and command contents included in a response signal to be received from the other communication device, it may instruct the first communication unit 201 and the first measurement unit 202 based on this information. When the control unit 205 does not receive a request (NO in S1005), it ends the cooperation processing between communication devices.

[0073] When the first communication unit 201 receives the first signal transmitted by the wireless device 100, the control unit 205 acquires information such as a tag ID included in the first signal (S1007). When the first measurement unit 202 measures the signal reception strength and signal arrival time of the first signal transmitted by the wireless device 100 (S1008), the control unit 205 acquires them as measurement results, associates the tag ID with the measurement results, and records them in the storage unit 208. Then, the control unit 205 determines whether it has received a request from the other communication device to notify the measurement results (S1009). When the control unit 205 has received a request from the other communication device to notify the measurement results (YES in S1009), it notifies the other communication device of the measurement results recorded in the storage unit 208 using the second communication unit 203 (S1010), and ends the process. If the control unit 205 does not receive a request from the other communication device to notify the measurement result (NO in S1009), the control unit 205 ends the cooperation process between the communication devices.

[0074] Returning to FIG. 8, the description will be continued. If there is an instruction to end detection of the wireless device 100 (YES in S806), the control unit 205 ends the process. If the control unit 205 has instructed the first communication unit 201 to periodically detect the wireless device 100, the control unit 205 instructs the first communication unit 201 to stop the operation. If there is no instruction to end detection of the wireless device 100 (NO in S806), the control unit 205 returns to S802 and continues the process. Note that, in this embodiment, a case is shown in which the process of detecting the wireless device 100 by the first communication unit 201 (S802 and S803) and the process of detecting other communication devices (S804 and S805) are executed consecutively, but these processes may be executed in parallel.

[0075] (Example of operation when communication apparatus 110 estimates the position of wireless device 100) 11 shows an example of an operation of estimating the position of the wireless device 100 by the communication device 110. In this embodiment, for example, as described above, it is assumed that there are two communication devices 111 and 112 and three wireless devices 101 to 103, the wireless devices 101 and 102 are reference tags, and the wireless device 103 is an item tag. It is assumed that the communication device 111 detects the wireless device 103 and the communication device 112. It is also assumed that the communication devices 111 and 112 obtain their respective position information based on the position information of each wireless device 100 by detecting the wireless devices 101 and 102, respectively.

[0076] The communication device 111 transmits a second signal using the first communication unit 201, and detects the wireless device 103 by receiving a first signal in response to the second signal (t=T1100). The communication device 111 measures the distance C between the communication devices 111 and 112 by UWB communication using the second communication unit 203 and the second measurement unit 204 (t=T1101). If the distance C is within a threshold, the communication device 111 starts inter-device cooperation processing with the communication device 112, and requests the communication device 112 to receive the first signal transmitted by the wireless device 103 and perform measurement. In addition, the communication device 111 obtains location information of the communication device 112 from the communication device 112. When the communication device 112 responds that it accepts the request, the communication device 111 transmits the second signal using the first communication unit 201. Then, the communication devices 111 and 112 receive a first signal transmitted by the wireless device 103 (t=T1102). The communication devices 111 and 112 use this first signal to measure the signal reception strength, the signal arrival time, and the like. The communication device 111 acquires the signal reception strength, the signal arrival time, and the like measured by the communication device 112 from the communication device 112, and identifies the distance A between the communication device 111 and the wireless device 103 and the distance B between the communication device 112 and the wireless device 103 (t=T1103). Then, the communication device 111 estimates the position of the wireless device 103 based on the identified distances A and B and the respective position information of the communication devices 111 and 112.

[0077] According to this embodiment, when the wireless device 100 is detected by the communication device 110, the communication device 110 estimates the position information of the item tag by performing inter-device cooperation with the other communication devices 110. Specifically, the communication device 110 operating as the controlled device also receives a response signal from the wireless device 100 in response to a signal transmitted by the communication device 110 operating as the control device. Using the same response signal, the position information of the wireless device 100 is estimated using the distance between the wireless device 100 and the wireless device 100 measured by each of the multiple communication devices 110 and the position information of each communication device 110. As a result, even if the wireless device 100 detected by the communication device 110 is located far away from the communication device 110, it is possible to reduce the error between the position information associated with the wireless device 100 and the actual position.

[0078] (Modification) In the above embodiment, an example in which the communication device 111 estimates the position of the wireless device 103 has been described, but the estimation of the position of the wireless device 103 may be performed by another device. For example, the information processing device 120 may estimate the position of the wireless device 103 using information acquired from the communication device 111 and the communication device 112. In this case, as an example, the communication device 111 may notify the information processing device 120 of the tag ID of the wireless device 103 detected using the first communication unit 201 and the measurement results such as the signal reception strength and the signal arrival time measured using the first communication unit 202. In addition, the communication device 111 may notify the information processing device 120 of the position information of the communication device 111 when notifying the information processing device 120 of these tag IDs and the measurement results. The communication device 112 may notify the information processing device 120 of the tag ID of the wireless device 103 detected using the first communication unit 201 and the measurement results such as the signal reception strength and the signal arrival time measured using the first communication unit 202. The communication device 112 may also notify the information processing device 120 of the location information of the communication device 112 when notifying the information processing device 120 of these tag IDs and the measurement results. The information processing device 120 may specify the distances A and B between the communication devices 111 and 112 and the wireless device 103, respectively, using the measurement results notified from each of the communication devices 111 and 112. The information processing device 120 may estimate the location of the wireless device 103, using the specified distances A and B and the location information of each of the communication devices 111 and 112. The communication device 111 may also notify the information processing device 120 of the distance A specified using the signal reception strength and signal arrival time of the first signal by the wireless device 103 measured by the first measurement unit 201. The communication device 111 may also notify the information processing device 120 of the distance B specified using the signal reception strength and signal arrival time of the first signal by the wireless device 103 measured by the first measurement unit 201 of the communication device 112. The information processing device 120 may estimate the position of the wireless device 103 using the distance A and distance B notified from the communication device 111 and the position information of each of the communication devices 111 and 112.The information processing device 120 records the estimated position of the wireless device 103 in the coordinates 713 of the item tag management table corresponding to the tag ID notified from the communication devices 111 and 112 .

[0079] According to this modification, the information processing device 120 estimates the location information of the wireless device 100, and therefore it is possible to reduce the processing load on the communication device 110. Furthermore, if the information processing device 120 accumulates information acquired from other communication devices 110, it becomes possible to estimate location information with higher accuracy using the information.

[0080] (Embodiment 2) In this embodiment, each of the multiple communication devices 110 operates in turn as a control device, and performs a cooperative process between the communication devices 110 to estimate the location information of the wireless device 100. The location information of the wireless device 100 is estimated by performing a statistical process using the location information of the wireless device 100 estimated by each communication device 110. An example of the statistical process is averaging the location information of the wireless device 100 estimated by each communication device 110, removing outliers, etc. Note that in this embodiment, after a certain communication device 110 estimates the location information of the wireless device 100 as a control device, instructing the other communication devices 110 to estimate the location information of the wireless device 100 is called a handover process.

[0081] Fig. 12 shows an example of a flowchart of a process performed by the communication apparatus 110 according to the present embodiment to detect the wireless device 100 and estimate its position. The processes of S801 to S805 in Fig. 12 are similar to those of S801 to S805 in Fig. 8, so they are denoted by the same numbers and description thereof will be omitted.

[0082] In this embodiment, the process from S1201 onward will be described on the assumption that the communication device 110 has executed the processes of S801 to S805. In S1201 of FIG. 12, the control unit 205 sets a flag for identifying whether the device 110 is operating as a control device or as a controlled device. For example, the control unit 205 sets the flag to 0 when operating as a control device. On the other hand, the control unit 205 sets the flag to 1 when operating as a controlled device. Then, the control unit 205 determines whether to perform handover processing for the other communication device 110 (S1202). For example, the control unit 205 may determine to perform handover processing when performing cooperation processing between the other communication device 110 and the communication device. When performing handover processing for the other communication device 110 (YES in S1202), the control unit 205 executes handover processing (S1203). When not performing handover processing for the other communication device 110, the control unit 205 advances the process to S1204.

[0083] A handover process from the communication device 110 to another communication device 110 executed in S1203 will be described with reference to FIG. 13. First, the control unit 205 uses the second communication unit 203 to determine whether or not the other communication device 110 has been detected (S1301). If the other communication device 110 has been detected (YES in S1301), the control unit 205 executes a process of measuring the distance between the devices using the second measurement unit 204 (S1302). If the other communication device 110 has not been detected (NO in S1301), the control unit 205 ends the handover process. In the process of measuring the distance between the devices, the control unit 205 sets a period (counting period) for counting the measurement results. For example, the time Ta to Tb is set as the counting period. The control unit 205 measures the distance between the detected other communication device 110 using the second measurement unit 204 over the counting period. The control unit 205 counts the distance between each communication device 110, which is the measurement result, for each detected communication device 110. When the measurement for all communication devices 110 detected in S1301 is performed within the counting period and the measurement result for each communication device 110 is obtained, the control unit 205 advances the process to S1303. On the other hand, when the measurement result for all communication devices 110 detected in S1301 is not obtained, the control unit 205 changes the counting period to be longer and continues measuring the distance between the communication devices 110. For example, the control unit 205 may extend the counting period by adding α to the time Tb while maintaining the time Ta. When the measurement result for all communication devices 110 detected in S1301 is obtained, the control unit 205 advances the process to S1303. The control unit 205 determines for each communication device 110 whether the communication device 110 stored in the storage unit 208 in S1003 of FIG. 10 is the same as the communication device 110 measured in S1302 (S1303). When detecting communication devices 110 in S1003 and S1302, control unit 205 may obtain the device ID from each communication device 110 and compare these device IDs to determine whether communication devices 110 are the same or not.If the detected communication device 110 is the same as the communication device 110 recorded in the storage unit 208 (YES in S1304), the control unit 205 judges whether the communication device 110 itself is operating as a control device or as a controlled device (S1305). If the detected communication device 110 is not the same as the communication device 110 recorded in the storage unit 208 (NO in S1304), the control unit 205 ends the handover process. The control unit 205 judges whether the communication device 110 is operating as a control device or as a controlled device based on the flag set in S1201. If the flag is 0 (NO in S1305), the control unit 205 judges that the communication device 110 is operating as a control device and proceeds to the process in S1306. If the flag is 1 (YES in S1305), the control unit 205 judges that the communication device 110 is operating as a controlled device and proceeds to the process in S1310.

[0084] If the communication device 110 is operating as a control device (NO in S1305), the control unit 205 uses the result of the measurement in S1302 to select the communication device 110 with the closest distance as the communication device of the handover destination (S1306). Note that if there are multiple other communication devices 110 whose distances to the communication device 110 are below a threshold, any one of the multiple communication devices 110 may be selected as the communication device of the handover destination randomly or based on a predetermined rule. The control unit 205 uses the second communication unit 203 to request the communication device of the handover destination to take over the process (S1307). The control unit 205 determines whether or not a response indicating that the request for handover is accepted is received from the communication device of the handover destination (S1308). If a response is received (YES in S1308), the control unit 205 ends the process of detecting the wireless device by the first communication unit 201 (S1309), and also ends the handover process. If the control unit 205 does not receive a response (NO in S1308), the control unit 205 ends the handover process.

[0085] When the communication device 110 is operating as a controlled device (YES in S1305), the control unit 205 judges whether or not a request for taking over processing has been received from the control device (S1310). When the control unit 205 receives a request for taking over processing from the control device (YES in S1310), the control unit 205 judges whether or not to accept the request for taking over processing. When the control unit 205 does not receive a request for taking over processing from the control device (NO in S1310), the control unit 205 ends the takeover processing. When the control unit 205 accepts the request for taking over processing, the control unit 205 transmits a response indicating that the request for taking over processing is accepted (S1311). Then, the control unit 205 starts transmitting a first signal for detecting the wireless device 100 using the first communication unit 201 (S1312), and ends the takeover processing.

[0086] Returning to Fig. 12, the description will continue. The control unit 205 initializes the flag by setting it to 0. If an instruction to end detection of the wireless device 100 has been received (YES in S806), the control unit 205 ends the process. Note that, if the control unit 205 has instructed the first communication unit 201 to periodically detect the wireless device 100, the control unit 205 instructs the first communication unit 201 to stop this operation. If the control unit 205 has not received an instruction to end detection of the wireless device 100 (NO in S806), the control unit 205 returns to S802 and continues the process.

[0087] (Example of operation when communication apparatus 110 estimates the position of wireless device 100) 14 shows an example of an operation for estimating the position of the wireless device 100 by the communication apparatus 110 according to this embodiment. In this embodiment, it is assumed that the example of the operation from t=T1100 to T1103 has been executed as in the case of FIG. 11 of the first embodiment, and the following example of the operation from t=T1400 to T1403 will be described.

[0088] The communication device 111 estimates the location information of the wireless device 103 by performing the operation from t=T1100 to T1103, and notifies the information processing device 120 of the estimated location information. Then, the communication device 111 sets a counting period for performing the handover process, and measures the distance between the communication device 112 and the other communication device. In this embodiment, it is assumed that the communication device 112 is detected during the counting period and matches the device ID recorded in the storage unit 208. Also, it is assumed that the distance between the communication device 111 and the communication device 112 is the shortest in comparison with the distance between the other communication device and the communication device 111 based on the measurement result during the counting period. The communication device 111 selects the communication device 112 as the handover destination of the process, and requests the handover of the process. When a response to this request is received, the communication device 111 stops the detection of the wireless device 100 by the first communication unit.

[0089] On the other hand, the communication device 112 starts transmitting a second signal using the first communication unit 201, and detects the wireless device 103 by receiving the second signal in response to the first signal (t=T1400). The communication device 112 measures the distance C' between the communication devices 112 and 111 by UWB communication using the second communication unit 203 and the second measurement unit 204 (t=T1401). If the distance C' is within the threshold, the communication device 112 starts inter-device cooperation processing with the communication device 111, and requests the communication device 111 to receive the first signal transmitted by the wireless device 103 and perform measurement using the first signal. In addition, the communication device 112 obtains location information of the communication device 111 from the communication device 111. When the communication device 112 receives a response from the communication device 111 indicating that the request is accepted, the communication device 112 transmits the second signal using the first communication unit 201. Then, the communication devices 112 and 111 receive the first signal transmitted by the wireless device 103 (t=T1402). The communication devices 112 and 111 measure the signal reception strength, the signal arrival time, and the like using this first signal. The communication device 112 acquires the signal reception strength, the signal arrival time, and the like measured by the communication device 111, and identifies the distance A' between the communication device 112 and the wireless device 103 and the distance B' between the communication device 111 and the wireless device 103 (t=T1403). Then, the communication device 112 estimates the position of the wireless device 103 based on the identified distances A' and B' and the respective position information of the communication devices 112 and 111. The communication device 112 notifies the information processing device 120 of the estimated position of the wireless device 103.

[0090] The information processing device 120 performs statistical processing using the location information of the wireless device 103 estimated by the communication devices 111 and 112. For example, the information processing device 120 averages the location information. By averaging, it is possible to reduce errors in the estimation results of the location information of the wireless device 103 by each communication device 110. In addition, in the averaging process, weighting based on the signal reception strength of the first signal received by each communication device 110 from the wireless device 103 may be performed. In general, the closer the distance between the communication device and the wireless device, the higher the signal reception strength. By performing weighting so that the estimation result by the communication device 110 that is closer to the wireless device 103 is emphasized, it is possible to obtain a more likely estimation result. In addition, when the information processing device 120 can use the estimation results of the location information of the wireless device 100 by three or more communication devices 110, it may average the estimation results by excluding outliers. Depending on the positional relationship between the communication device 110 and the wireless device 100, the estimation of the location information of the wireless device 100 may include a large error due to the influence of multipath in the wireless channel. By comparing the estimation results obtained by other communication devices 110 and excluding such estimation results containing large errors as outliers, the accuracy of the estimation results can be improved.

[0091] According to this embodiment, it is possible to estimate the position of the wireless device 100 with higher accuracy by performing statistical processing on the position information of the wireless device 100 estimated by the multiple communication devices 110. For example, by removing outliers from the position information of the wireless device 100 estimated by each communication device 110 and averaging the information, it is possible to reduce errors specific to the positional relationship between the wireless device 100 and each communication device 110 and perform highly accurate position estimation.

[0092] The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions.

[0093] (Summary of the embodiment) At least some of the above-described embodiments can be summarized as follows. (Item 1) an acquisition means for acquiring a first distance between the wireless device and the first communication device, the first distance being determined based on a result of a first communication device measuring a first signal that the first communication device has caused a wireless device to transmit, the first distance being determined based on a result of a second communication device measuring the first signal that the first communication device has caused the wireless device to transmit, the second distance being determined based on a result of a second communication device measuring the first signal that the first communication device has caused the wireless device to transmit, the second distance being determined based on a result of a second communication device measuring the first distance being determined based on a result of a second communication device measuring the first signal that the first communication device has caused the wireless device to transmit, the second distance being determined based on a result of a an estimation means for estimating a location of the wireless device based on the first distance, the second distance, the first location information, and the second location information; An estimation device comprising: (Item 2) The estimation device described in item 1, characterized in that the acquisition means includes a determination means that determines the first distance based on a transmission time at which the first signal is transmitted from the wireless device and a first reception time at which the first signal is received at the first communication device, and that determines the second distance based on the transmission time and a second reception time at which the first signal is received at the second communication device. (Item 3) The estimation device according to item 2, characterized in that the determination means determines the transmission time based on a time when a predetermined signal for causing the wireless device to transmit the first signal was transmitted from the first communication device to the wireless device. (Item 4) The estimation device described in item 2, characterized in that the acquisition means includes a determination means that determines the first distance based on a first reception strength when the first signal is received at the first communication device, and determines the second distance based on a second reception strength when the first signal is received at the second communication device. (Item 5) 5. The estimation device according to any one of items 1 to 4, wherein the acquisition means further includes control means for controlling the first communication device to transmit a predetermined signal to cause the wireless device to transmit the first signal using a first method, which is a communication method for communication between the first communication device and the wireless device, and to measure the first signal transmitted by the wireless device in response to the predetermined signal. (Item 6) The first method is a communication method using RFID. 6. The estimation device according to item 5, (Item 7) 7. The estimation device according to item 5 or 6, characterized in that the control means controls the first communication device to transmit a second signal to the first communication device instructing the second communication device to receive the first signal. (Item 8) 8. The estimation device according to claim 7, wherein the second signal includes information enabling the second communication device to identify the first signal. (Item 9) 9. The estimation device according to item 7 or 8, wherein the second signal is communicated in a second manner different from the first manner. (Item 10) 10. The estimation device according to item 9, wherein the second method is an Ultra Wide Band communication method. (Item 11) 10. The estimation device according to item 9, wherein the second method is a communication method conforming to the Bluetooth standard. (Item 12) 12. The estimation device according to any one of items 1 to 11, wherein at least one of the first location information and the second location information is identified based on third location information of another wireless device whose location is known and is acquired by the first communication device from the other wireless device. (Item 13) Item 13. The estimation device according to item 12, characterized in that the first location information is identified using a location of the first communication device and a movement amount of the first communication device when the third location information is acquired. (Item 14) The estimation means estimates a position of the wireless device using the second distances and the second position information acquired by the acquisition means for two or more of the second communication devices. 14. The estimation device according to any one of items 1 to 13, (Item 15) 10. The estimation device according to item 9, wherein the control means controls the first communication device to measure a third distance between the first communication device and the second communication device using the second scheme. (Item 16) The estimation device described in item 15, characterized in that when a difference between a fourth distance determined from the first location information of the first communication device and the second location information of the second communication device and the third distance is smaller than a threshold value, the estimation means estimates the location of the wireless device using the second distance and the second location information acquired for the second communication device. (Item 17) The estimation device described in item 15, characterized in that when a difference between a fourth distance determined from the first location information of the first communication device and the second location information of the second communication device and the third distance exceeds a threshold, the estimation means does not use the second distance and the second location information acquired for the second communication device to estimate the location of the wireless device. (Item 18) 18. The estimation device according to any one of items 15 to 17, characterized in that, when the third distance does not exceed a threshold, the estimation means estimates the position of the wireless device using the second distance and the second position information for the second communication device corresponding to the third distance. (Item 19) 19. The estimation device according to any one of items 15 to 18, wherein the acquisition means corrects the second position information by using the third distance. (Item 20) and an instruction means for instructing another communication device other than the first communication device to transmit the predetermined signal for causing the wireless device to transmit the first signal after estimating the position of the wireless device. 6. The estimation device according to item 5, (Item 21) The estimation device is included in the first communication device. 21. The estimation device according to any one of items 1 to 20, (Item 22) 21. The estimation device according to any one of items 1 to 20, characterized in that the estimation device is an information processing device different from the first communication device, the second communication device, and the wireless device. (Item 23) An estimation method performed by an estimation device, comprising: an acquiring process for acquiring a first distance between the wireless device and the first communication device, the first distance being determined based on a result of a first communication device measuring a first signal that the first communication device has caused a wireless device to transmit, the first distance being between the wireless device and the first communication device; a second distance being determined based on a result of a second communication device measuring the first signal that the first communication device has caused the wireless device to transmit, the second distance being between the wireless device and the second communication device; first location information indicating a location of the first communication device; and second location information indicating a location of the second communication device; estimating a location of the wireless device based on the first distance, the second distance, the first location information, and the second location information; The estimation method according to claim 1, (Item 24) A program for causing a computer to function as the estimation device according to any one of items 1 to 22.

[0094] The present disclosure is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the present disclosure. [Explanation of symbols]

[0095] 103: wireless device, 111: communication device, 112: communication device, 206: distance determination unit, 207: distance estimation unit

Claims

1. an acquisition means for acquiring a first distance between the wireless device and the first communication device, the first distance being determined based on a result of a first communication device measuring a first signal that the first communication device has caused a wireless device to transmit, the first distance being between the wireless device and the first communication device; a second distance being determined based on a result of a second communication device measuring the first signal that the first communication device has caused the wireless device to transmit, the second distance being between the wireless device and the second communication device; first location information indicating a location of the first communication device; and second location information indicating a location of the second communication device; an estimation means for estimating a location of the wireless device based on the first distance, the second distance, the first location information, and the second location information; An estimation device comprising:

2. The estimation device of claim 1, characterized in that the acquisition means includes a determination means for determining the first distance based on a transmission time at which the first signal is transmitted from the wireless device and a first reception time at which the first signal is received at the first communication device, and for determining the second distance based on the transmission time and a second reception time at which the first signal is received at the second communication device.

3. 3. The estimation device according to claim 2, wherein the determination means determines the transmission time based on a time when a predetermined signal for causing the wireless device to transmit the first signal is transmitted from the first communication apparatus to the wireless device.

4. The estimation device described in claim 2, characterized in that the acquisition means includes a determination means for determining the first distance based on a first reception strength when the first signal is received at the first communication device, and for determining the second distance based on a second reception strength when the first signal is received at the second communication device.

5. 2. The estimation device according to claim 1, wherein the acquisition means further includes control means for controlling the first communication device to transmit a predetermined signal to cause the wireless device to transmit the first signal using a first method, which is a communication method for communication between the first communication device and the wireless device, and to measure the first signal transmitted by the wireless device in response to the predetermined signal.

6. The first method is a communication method using RFID.

6. The estimation device according to claim 5 .

7. 6. The estimation device according to claim 5, wherein the control means controls the first communication device to transmit a second signal to the first communication device instructing the second communication device to receive the first signal.

8. 8. The apparatus of claim 7, wherein the second signal includes information enabling the second communication device to identify the first signal.

9. 8. The apparatus of claim 7, wherein the second signal is communicated in a second manner different from the first manner.

10. 10. The estimation device according to claim 9, wherein the second method is an Ultra Wide Band communication method.

11. 10. The estimation device according to claim 9, wherein the second method is a communication method conforming to the Bluetooth standard.

12. 2. The estimation device according to claim 1, wherein at least one of the first location information and the second location information is identified based on third location information of another wireless device whose location is known and obtained by the first communication device from the other wireless device.

13. The estimation device according to claim 12 , wherein the first location information is identified using a location of the first communication device and a movement amount of the first communication device when the third location information is acquired.

14. The estimation means estimates a position of the wireless device using the second distances and the second position information acquired by the acquisition means for two or more of the second communication devices.

2. The estimation device according to claim 1 .

15. 10. The estimation device according to claim 9, wherein the control means controls the first communication device to measure a third distance between the first communication device and the second communication device using the second technique.

16. The estimation device according to claim 15, characterized in that the estimation means estimates the position of the wireless device using the second distance and the second position information acquired for the second communication device when a difference between a fourth distance determined from the first position information of the first communication device and the second position information of the second communication device and the third distance is smaller than a threshold value.

17. The estimation device of claim 15, characterized in that the estimation means does not use the second distance and the second location information acquired for the second communication device to estimate the location of the wireless device when a difference between a fourth distance determined from the first location information of the first communication device and the second location information of the second communication device and the third distance exceeds a threshold value.

18. 16. The estimation device of claim 15, wherein the estimation means estimates the position of the wireless device using the second distance and the second location information for the second communication device corresponding to the third distance when the third distance does not exceed a threshold.

19. The estimation device according to claim 15 , wherein the acquisition means modifies the second position information using the third distance.

20. and an instruction means for instructing another communication device other than the first communication device to transmit the predetermined signal for causing the wireless device to transmit the first signal after estimating the position of the wireless device.

6. The estimation device according to claim 5 .

21. The estimation device is included in the first communication device.

2. The estimation device according to claim 1 .

22. The estimation apparatus according to claim 1 , wherein the estimation apparatus is an information processing apparatus different from the first communication apparatus, the second communication apparatus, and the wireless device.

23. An estimation method performed by an estimation device, comprising: an acquiring process for acquiring a first distance between the wireless device and the first communication device, the first distance being determined based on a result of a first communication device measuring a first signal that the first communication device has caused a wireless device to transmit, the first distance being between the wireless device and the first communication device; a second distance between the wireless device and the second communication device, the second distance being determined based on a result of a second communication device measuring the first signal that the first communication device has caused the wireless device to transmit, the second distance being between the wireless device and the second communication device; first location information indicating a location of the first communication device; and second location information indicating a location of the second communication device; estimating a location of the wireless device based on the first distance, the second distance, the first location information, and the second location information; The estimation method according to claim 1,

24. A program for causing a computer to function as the estimation device according to any one of claims 1 to 22.

Images