JP5950353B2 - Wireless communication apparatus, apparatus search method, and program - Google Patents

Description

  The present invention relates to a wireless communication device, and more particularly to a wireless communication device that searches for a device using signal strength.

  Various methods are used to measure the distance between wireless communication terminals using radio waves. By measuring the distance between the wireless communication terminals, it is possible to realize services such as preventing the wireless communication terminals from being left behind or searching for lost children. Furthermore, in the event of a major earthquake, it may be possible to search for people from the rubble by measuring the distance between wireless communication terminals. Therefore, a technique for measuring the distance between wireless communication terminals with high accuracy is required.

  For example, Patent Literature 1 discloses a technique for measuring a distance between wireless communication terminals using a delay time of a signal communicated between the wireless communication terminals.

  Further, Patent Document 2 discloses a technique for measuring the distance between wireless communication terminals using the radio wave intensity of a signal communicated between the wireless communication terminals. Specifically, the receiver that receives the signal transmitted from the transmitter detects the signal strength of the received signal multiple times. The state detection system in Patent Literature 2 determines whether the transmitter and the receiver are close, separated, or stationary according to the measurement result of the signal strength at the receiver.

Japanese Patent Laid-Open No. 2006-174381 JP 2007-047064 A

  However, the state detection system disclosed in Patent Document 2 has the following problems. For example, when the transmission power of a signal transmitted from the transmitter is changed, the reception power at the receiver changes even when the transmitter and the receiver are stationary. That is, the state detection system disclosed in Patent Document 2 has a problem that the distance between the wireless communication terminals cannot be measured correctly when the transmission power of the signal transmitted from the transmitter changes.

  In order to solve the above-described problem, an object of the present invention is a wireless communication apparatus capable of correctly detecting a change in distance between wireless communication terminals even when transmission power of a signal transmitted from a transmitter changes. Another object of the present invention is to provide a searched device, a device searching method and a program.

  The wireless communication device according to the first aspect of the present invention includes a transmission unit that transmits first and second wireless signals to a searched device, and the first and second wireless signals measured in the searched device. When the transmission intensity in the first and second radio signals is in a specific situation, and the reception unit that receives information on the reception intensity of the first and second radio signals, the transmission intensity in the first and second radio signals And correcting the reception strength of at least one of the first and second radio signals based on the corrected received signal strength of the first and second radio signals, And a processing unit for detecting a change.

  When the searched device according to the second aspect of the present invention receives a radio signal in which an information element indicating that a change in the distance between the searched device and the wireless communication device is detected is received, the searched device Information used to detect a change in the distance between the device and the wireless communication device is set as a response signal to the wireless signal and transmitted to the wireless communication device.

  The apparatus search method concerning the 3rd aspect of this invention transmits the 1st and 2nd radio signal to a to-be-searched apparatus, and the receiving intensity of the said 1st and 2nd radio signal measured in the to-be-searched apparatus Is received from the searched device, it is determined whether there is a difference in transmission strength between the first and second radio signals, and there is a difference in transmission strength between the first and second radio signals. In this case, the reception strength of at least one of the first and second radio signals is corrected using a difference in transmission strength between the first and second radio signals, and the corrected first and second radio signals are corrected. A change in the distance to the search target device is detected in accordance with the signal reception intensity.

  The program according to the fourth aspect of the present invention transmits the first and second radio signals to the searched device, and information on the reception strengths of the first and second wireless signals measured by the searched device. Is received from the searched device, it is determined whether there is a difference in transmission strength between the first and second radio signals, and there is a difference in transmission strength between the first and second radio signals, The reception intensity of at least one of the first and second radio signals is corrected using a difference in transmission intensity between the first and second radio signals, and the corrected first and second radio signals are corrected. The computer is caused to detect a change in the distance to the search target device in accordance with reception intensity.

  The present invention provides a wireless communication device, a searched device, a device search method, and a program capable of correctly measuring the distance between wireless communication terminals even when the transmission intensity of a signal transmitted from a transmitter changes. be able to.

1 is a configuration diagram of a wireless communication apparatus according to a first exemplary embodiment. FIG. 3 is a configuration diagram of a communication system according to a second exemplary embodiment. FIG. 3 is a configuration diagram of a mobile phone according to a second embodiment; It is a block diagram of the access point concerning Embodiment 2. FIG. It is a figure which shows the distance estimation information element concerning Embodiment 2. FIG. It is a figure which shows the distance estimation response information element concerning Embodiment 2. FIG. It is a figure which shows the flow of the transmission process of the beacon signal concerning Embodiment 2. FIG. It is a figure which shows the flow of a process between AP and mobile telephone concerning Embodiment 2. FIG. It is a figure which shows the flow of the reception process of the beacon signal concerning Embodiment 2. FIG. It is a figure which shows the flow of the reception process of the ProbeReQ signal concerning Embodiment 2. FIG. It is a figure which shows the flow of the process which detects the change of the distance between AP and mobile telephone concerning Embodiment 2. FIG. It is a figure which shows the flow of the process which detects the change of the distance between AP and mobile telephone concerning Embodiment 2. FIG. It is a figure which shows the flow of the process which detects the change of the distance between AP and mobile telephone concerning Embodiment 2. FIG. It is a figure which shows the flow of the process which detects the change of the distance between AP and mobile telephone concerning Embodiment 2. FIG. It is a figure which shows the flow of the process which detects the change of the distance between AP and mobile telephone concerning Embodiment 2. FIG. It is a figure which shows the flow of the process which detects the change of the distance between AP and mobile telephone concerning Embodiment 2. FIG. It is a figure which shows the flow of the process which detects the change of the distance between AP and mobile telephone concerning Embodiment 2. FIG. It is a figure which shows the flow of the transmission process of the beacon signal concerning Embodiment 3. FIG. It is a figure which shows the distance estimation information element concerning Embodiment 4. FIG. It is a figure which shows the flow of the reception process of the beacon signal concerning Embodiment 4. FIG.

(Embodiment 1)
Embodiments of the present invention will be described below with reference to the drawings. First, a configuration example of the wireless communication apparatus according to the first embodiment of the present invention will be described with reference to FIG. The wireless communication device 10 includes a transmission unit 11, a reception unit 12, and a processing unit 13. Here, the wireless communication device 10 is a device that searches for the searched device 20 using a wireless signal.

  The transmission unit 11 transmits a radio signal to the searched device 20. The transmission unit 11 transmits the radio signal to the search target device 20 a plurality of times. When there are a plurality of search target devices 20 around the wireless communication device 10, the transmission unit 11 transmits a radio signal to the plurality of search target devices 20. Here, the radio signal may be a beacon signal, for example, or may be a broadcast signal broadcast to a plurality of wireless terminals, a notification signal, or the like.

  The receiving unit 12 receives information related to the reception strength of the radio signal measured by the searched device 20 from the searched device 20. For example, when the searchee device 20 receives a plurality of radio signals, the search target device 20 measures the reception intensity for each received radio signal. The searched device 20 transmits information about the measured reception strength to the wireless communication device 10. When the wireless signal is transmitted to the search target device 20 a plurality of times from the transmission unit 11, the reception unit 12 receives information on a plurality of reception strengths from the search target device 20.

  The processing unit 13 detects a change in the distance between the wireless communication device 10 and the searched device 20 according to the information regarding the plurality of reception strengths received by the receiving unit 12. The change in the distance between the wireless communication device 10 and the searched device 20 is, for example, that the distance between the wireless communication device 10 and the searched device 20 is increased, or that the wireless communication device 10 and the searched device 20 are separated. And the distance between the wireless communication device 10 and the searched device 20 does not change.

  For example, when the reception strength related to the next wireless signal transmitted from the transmission unit 11 is greater than the reception strength related to the wireless signal transmitted next, the processing unit 13 determines whether the wireless communication device 10 and the searched device 20 It may be determined that the distance between has approached. In addition, when the reception strength related to the radio signal transmitted next is smaller than the reception strength related to the radio signal transmitted first from the transmission unit 11, the processing unit 13 determines whether the radio communication device 10 and the searched device 20 It may be determined that the distance between is separated.

  Alternatively, when the reception unit 12 receives information on a plurality of reception strengths of 3 or more, a change in distance may be detected as follows. The processing unit 13 arranges information related to a plurality of reception strengths in the order of reception, and when the reception strength tends to increase, the processing unit 13 determines that the distance between the wireless communication device 10 and the search target device 20 is close, and receives When the strength tends to decrease, it may be determined that the distance between the wireless communication device 10 and the searched device 20 has approached.

  Further, the processing unit 13 determines whether or not there is a difference in transmission strength among a plurality of radio signals transmitted from the transmission unit 11 to the search target device 20. If the processing unit 13 determines that there is a difference in transmission strength, the reception unit 12 corrects the reception strength of the radio signal received from the search target device 20 by using the difference in transmission strength. The processing unit 13 detects a change in the distance between the wireless communication device 10 and the searched device 20 using the corrected received intensity.

  As described above, by using the wireless communication device 10 according to the first exemplary embodiment of the present invention, the wireless communication device 10 uses the information related to the reception strength of the wireless signal received by the searched device 20 to be searched. A change in the distance to the device 20 can be detected. Further, even when the transmission strength of the radio signal transmitted from the wireless communication device 10 to the searched device 20 changes, the value of the received strength in the searched device 20 can be corrected for the difference in transmission strength. Thereby, even when the transmission intensity of the radio signal transmitted from the radio communication device 10 changes, a change in the distance between the radio communication device 10 and the searched device 20 can be detected with high accuracy.

(Embodiment 2)
Subsequently, a configuration example of the communication system according to the second exemplary embodiment of the present invention will be described with reference to FIG. The communication system in FIG. 2 includes a wireless LAN access point (AP) 101 and a mobile phone 201. For example, a communication method using a beacon, for example, a wireless WiFi communication method can be applied to the wireless LAN access point. The AP 101 corresponds to the wireless communication device 10 in FIG. Here, the AP 101 may be a portable AP that can be carried by the user. The mobile phone 201 corresponds to the searched device 20 in FIG. Further, in the figure, the mobile phone 201 is used as a specific terminal of the searched device 20, but the searched device 20 may be a smartphone terminal or a device such as a wristwatch having a communication function. In other words, the searched device 20 may be any device that has a communication function and can be carried by the user. Alternatively, the search target device 20 may be an HGW (Home GateWay) used for constructing a home LAN or the like. For example, the HGW can communicate with the AP 101 even when power can be stored or when power is not supplied due to a power failure or the like.

  AP 101 transmits a beacon signal including a distance estimation IE (Information Element) to mobile phone 201. IE is an information element set in the beacon signal. The distance estimation IE is information serving as a trigger for measuring the distance between the AP 101 and the mobile phone 201. Details of the distance estimation IE will be described later.

  When receiving the beacon signal including the distance estimation IE, the mobile phone 201 transmits an ieee80211 probe request frame (hereinafter referred to as ProbeReQ) signal including the distance estimation response IE to the AP 101 as a response signal. The distance estimation response IE is used in the AP 101 to determine a change in the distance from the mobile phone 201. Details of the distance estimation response IE will be described later.

  Next, a configuration example of the mobile phone 201 according to the second embodiment of the present invention will be described with reference to FIG. The mobile phone 201 has a mobile phone interface 202 and a wireless LAN interface 203. The mobile phone interface 202 is an interface used when communicating via a mobile phone network. The mobile phone network may be, for example, a so-called 3G network defined in 3GPP, an LTE (Long Term Evolution) network, or the like. The wireless LAN interface 203 is an interface used when communicating with the AP 101. The wireless LAN interface 203 may be an interface corresponding to a plurality of standards related to the wireless LAN. The mobile phone 201 also includes a human interface such as a CPU (Central Processing Unit), a memory, an LCD (Liquid Crystal Display), and buttons.

  The wireless LAN interface 203 receives the beacon signal transmitted from the AP 101. When the distance estimation IE is included in the beacon signal, the wireless LAN interface 203 measures the reception strength of the beacon signal. The reception intensity may be, for example, signal reception power. Further, the transmission strength described later may be, for example, signal transmission power. Further, the wireless LAN interface 203 sets information related to the measured reception strength in a ProbeReQ signal and transmits the information to the AP 101. The wireless LAN interface 203 may further transmit information necessary to be used for detecting a change in distance in the AP 101 to the AP 101 in addition to the information regarding the reception strength.

  Next, a configuration example of the AP 101 according to the second embodiment of the present invention will be described with reference to FIG. The AP 101 includes a wireless LAN interface 302, a beacon generation unit 303, a distance estimation response IE determination unit 305, a reception unit 308, a memory 309, an LED 310, and a wired LAN interface 311. The beacon generation unit 303 corresponds to the transmission unit 11 in FIG. The receiving unit 308 corresponds to the receiving unit 12 in FIG. The distance estimation response IE determination unit 305 corresponds to the processing unit 13 in FIG.

  The wireless LAN interface 302 includes a beacon generation unit 303, a distance estimation response IE determination unit 305, and a reception unit 308.

  The beacon generation unit 303 includes a distance estimation IE generation unit 304. The beacon generator 303 generates a beacon signal in which the distance estimate IE generated by the distance estimate IE generator 304 is set. The beacon generation unit 303 transmits the generated beacon signal to the mobile phone 201 that may exist around the AP 101. The beacon generation unit 303 stores information on the transmission intensity of the beacon signal (hereinafter referred to as transmission output) in the memory 309. The transmission output may be information regarding the transmission power of the signal, for example.

  Here, the distance estimation IE generated by the distance estimation IE generation unit 304 will be described with reference to FIG. The distance estimate IE includes a distance estimate request message for collecting information necessary for detecting a change in the distance between the AP 101 and the mobile phone 201 from the mobile phone 201. When the mobile phone 201 receives the distance estimation IE, the mobile phone 201 sets information necessary for detecting a change in the distance between the AP 101 and the mobile phone 201 to the ProbeReQ signal and transmits the information to the AP 101.

  Returning to FIG. 4, the receiving unit 308 receives the ProbeReQ signal transmitted from the mobile phone 201. Here, the distance estimation response IE set in the ProbeReQ signal will be described with reference to FIG. The distance estimation response IE includes information related to the reception strength of the beacon signal and the transmission output of the ProbeReQ signal.

  Returning to FIG. 4, the distance estimation response IE determination unit 305 uses the distance estimation response IE received by the reception unit 308 and the transmission output of the beacon signal stored in the memory 309 to determine the distance between the AP 101 and the mobile phone 201. Detect changes. Further, the distance estimate response IE determination unit 305 may use information related to the reception strength of the ProbeReQ signal in order to detect a change in the distance between the AP 101 and the mobile phone 201. The distance estimate response IE determination unit 305 includes a proximity counter 306 and a remote counter 307, and detects a change in the distance between the AP 101 and the mobile phone 201 using the proximity counter 306 and the remote counter 307. Also good. The proximity counter 306 and the remote counter 307 will be described in detail later.

  The LED 310 is used to notify a user or an administrator of the detection result or determination result in the distance estimation response IE determination unit 305. Alternatively, the detection result or determination result in the distance estimate response IE determination unit 305 may be output to a display unit or the like connected to the AP 101 via the wired LAN interface 311. Here, if the reception intensity of the beacon signal included in the ProbeReQ signal is not set because the mobile phone 201 cannot accurately measure the beacon signal, the transmission output of the beacon signal transmitted from the AP 101 may be too small. . In such a case, the beacon generation unit 303 may perform control so as to increase the transmission output of the beacon signal.

  Next, a flow of beacon signal transmission processing in the AP 101 will be described with reference to FIG. When the AP 101 starts a beacon signal transmission process (S401), it first initializes a proximity counter and a remote counter (S402). The proximity counter and the remote counter are used when the distance estimation response IE determination unit 305 cannot determine whether the distance between the AP 101 and the mobile phone 201 is approaching or away.

  Next, the beacon generation unit 303 generates a beacon signal (S403). Next, the distance estimate IE generation unit 304 generates a distance estimate IE. Next, the beacon generation unit 303 sets a distance estimation IE for the generated beacon signal (S405). Setting the distance estimate IE in the beacon signal has the same meaning as embedding the distance estimate IE in the beacon signal.

  Next, the beacon generation unit 303 stores the transmission output when transmitting the beacon signal in the memory 309 (S406). Next, the beacon generation unit 303 transmits the generated beacon signal to the mobile phone 201 (S407).

  When the process up to step S407 is completed in the AP 101, the mobile phone 201 performs a beacon signal reception process as shown in FIG.

  Next, a flow of beacon signal reception processing in the mobile phone 201 will be described with reference to FIG. After receiving the beacon signal (S601), the wireless LAN interface 203 determines whether the distance estimation IE is set in the received beacon signal (S602). If the wireless LAN interface 203 determines that the distance estimation IE is not set in the beacon signal, the wireless LAN interface 203 ends the process (S603).

  If the wireless LAN interface 203 determines that the distance estimation IE is set in the beacon signal, the wireless LAN interface 203 generates a ProbeReQ signal (S604). Next, the wireless LAN interface 203 sets the reception strength of the beacon signal in the distance estimation response IE (S605). Next, the wireless LAN interface 203 sets the transmission strength of the ProbeReQ signal to be transmitted to the AP 101 in the distance estimation response IE (S606). Next, the wireless LAN interface 203 sets the distance estimation response IE in which the reception strength of the beacon signal and the transmission strength of the ProbeReQ signal are set in the ProbeReQ signal (S607). Next, the wireless LAN interface 203 transmits a ProbeReQ signal to the AP 101 (S608).

  Here, as illustrated in FIG. 8, when the ProbeReQ signal is transmitted from the mobile phone 201 to the AP 101, the AP 101 executes a ProbeReQ signal reception process.

  Next, the flow of a ProbeReQ signal reception process in the AP 101 will be described with reference to FIG. First, the receiving unit 308 of the AP 101 determines whether or not the distance estimation response IE is set in the ProbeReQ signal transmitted from the mobile phone 201 (S701). When the reception unit 308 determines that the distance estimation response IE is not set in the ProbeReQ signal, the reception unit 308 repeats the process of step S403 in FIG.

  If the receiving unit 308 determines that the distance estimation response IE is set in the ProbeReQ signal, the receiving unit 308 generates response information (S702). The response information is information used to detect a change in the distance between the AP 101 and the mobile phone 201. Specifically, the response information includes the reception strength of the beacon signal and the transmission strength of the ProbeReQ signal set in the distance estimation response IE. Further, the response information includes the reception strength when the AP 101 receives the ProbeReQ signal. Further, the response information includes the transmission intensity of the beacon signal stored in the memory 309.

  Here, it is assumed that response information 1 and response information 2 are set in the memory 309 as areas for storing response information. The response information 2 stores newer information than the response information 1. That is, the response information 2 stores response information generated based on a beacon signal transmitted later from the AP 101 to the mobile phone 201 and a ProbeReQ signal that is a response signal of the beacon signal.

  In such a case, the receiving unit 308 determines whether or not the response information 1 is stored in the memory 309 (S703). When the response information 1 is not stored in the memory 309, the reception unit 308 stores the response information generated in step S702 as the response information 1 in the memory 309 (S704), and the AP 101 performs the process of step S403 in FIG. repeat. When the response information 1 is stored in the memory 309, the reception unit 308 stores the response information generated in step S702 in the memory 309 as the response information 2 (S705), and the AP 101 stores the response information described in FIG. Perform the process.

  Next, a processing flow for processing the response information to detect a change in the distance between the AP 101 and the mobile phone 201 will be described with reference to FIG.

  First, when the response information 1 and the response information 2 are stored in the memory 309, the distance estimation response IE determination unit 305 determines whether or not the beacon transmission output A of the response information 1 and the beacon transmission output B of the response information 2 are equal. Is determined (S802). When the beacon transmission output A and the beacon transmission output B are different, the distance estimation response IE determination unit 305 corrects the beacon reception intensity A of the response information 1 (S803). For example, the distance estimation response IE determination unit 305 corrects the beacon reception intensity A as corrected beacon reception intensity A = beacon reception intensity A + before correction (beacon transmission output B−beacon transmission output A). For example, when the second beacon transmission output is 3 dB higher than the first beacon transmission output performed by the distance estimation IE generation unit 304, the corrected beacon reception intensity is 3 dB added to the beacon reception intensity A before correction. Value. In addition, the distance estimate response IE determination unit 305 stores in advance a table associating the difference between the beacon transmission output A and the beacon transmission output B with the correction value of the beacon reception intensity A, and receives the distance estimate response IE. In this case, the correction value of the beacon reception intensity A may be specified using a table. By specifying the correction value of the beacon reception intensity A using the table in this way, the processing load can be reduced because the process of calculating the corrected beacon reception intensity A is not performed.

  When the beacon transmission output A and the beacon transmission output B are equal, or when the beacon reception intensity A is corrected, the distance estimation response IE determination unit 305 determines whether the beacon reception intensity B is greater than the beacon reception intensity A. (S804). Here, the beacon reception strength B is a beacon reception strength included in the response information 2. If the beacon reception intensity A is corrected in step S803, the corrected beacon reception intensity A is used.

  When it is determined that the beacon reception strength B is greater than the beacon reception strength A, the distance estimation response IE determination unit 305 determines whether the ProbeReQ transmission output A and the ProbeReQ transmission output B are equal (S805). The ProbeReQ transmission output A is a ProbeReQ transmission output included in the response information 1, and the ProbeReQ transmission output B is a ProbeReQ transmission output included in the response information 2.

  When the ProbeReQ transmission output A and the ProbeReQ transmission output B are different from each other, the distance estimation response IE determination unit 305 corrects the ProbeReQ reception intensity A of the response information 1 (S806). For example, the distance estimation response IE determination unit 305 corrects the ProbeReQ reception intensity A as follows: ProbeReQ reception intensity A after correction = ProbeReQ reception intensity A + before correction (ProbeReQ transmission output B−ProbeReQ transmission output A). For example, when the second ProbeReQ transmission output is 3 dB higher than the first ProbeReQ transmission output performed by the distance estimation IE generation unit 304, the corrected ProbeReQ reception intensity is 3 dB added to the beacon reception intensity A before correction. Value.

  When the ProbeReQ transmission output A and the ProbeReQ transmission output B are equal, or when the ProbeReQ reception strength A is corrected, the distance estimation response IE determination unit 305 determines whether the ProbeReQ reception strength B is equal to or higher than the ProbeReQ reception strength A ( S807). When the distance estimate response IE determination unit 305 determines that the ProbeReQ reception strength B is equal to or higher than the ProbeReQ reception strength A, the distance estimation response IE determination unit 305 executes the process of FIG.

  FIG. 12 shows the flow of processing when it is determined in step S807 that the ProbeReQ reception strength B is greater than or equal to the ProbeReQ reception strength A. In the following, the process in FIG. 12 will be described.

  If it is determined in step S807 that the ProbeReQ reception strength B is greater than or equal to the ProbeReQ reception strength A, the distance estimation response IE determination unit 305 updates the response information 1 in the memory 309 to the content of the response information 2 (S808). . That is, the distance estimation response IE determination unit 305 overwrites the response information 1 in the memory 309 with the content of the response information 2 and deletes the response information 2 from the memory 309.

  Next, the distance estimate response IE determination unit 305 determines that the AP 101 and the mobile phone 201 are close to each other (S809). That is, the distance estimation response IE determination unit 305 determines that the AP 101 and the mobile phone 201 are close to each other because the beacon reception strength B is greater than the beacon reception strength A and the ProbeReQ reception strength B is greater than the ProbeReQ reception strength A. To do.

  Next, the distance estimation response IE determination unit 305 initializes the proximity counter and the remote counter (S810). Next, the distance estimation response IE determination unit 305 outputs a determination result that the AP 101 and the mobile phone 201 are approaching to the display unit or the like via the LED 310 or the wired LAN interface 311 (S811). Thereby, the user having the AP 101 can grasp that the AP 101 and the mobile phone 201 are close to each other.

  Next, when repeatedly executing the process of detecting a change in the distance between the AP 101 and the mobile phone 201, the AP 101 repeats the process of step S403 in FIG. 7 (S812). If the AP 101 does not repeatedly execute the process of detecting the change in the distance between the AP 101 and the mobile phone 201, the process ends (S812).

  Subsequently, referring to FIG. 13, when it is determined in step S807 that the ProbeReQ reception strength B is not equal to or higher than the ProbeReQ reception strength A, that is, when it is determined that the ProbeReQ reception strength B is less than the ProbeReQ reception strength A. Will be described.

  In this case, the change in the distance between the AP 101 and the mobile phone 201 assumed from the comparison result of the beacon reception strength is different from the change in the distance between the AP 101 and the mobile phone 201 assumed from the comparison result of the ProbeReQ reception strength. Therefore, the distance estimation response IE determination unit 305 determines that there is a possibility that the AP 101 and the mobile phone 201 are close by applying the comparison result of the beacon reception strength (S815). Next, the distance estimation response IE determination unit 305 increments the value of the proximity counter by 1 (S816). As described above, the distance estimation response IE determination unit 305 determines using a proximity counter or a remote counter when it cannot make a definite determination regarding a change in the distance between the AP 101 and the mobile phone 201.

  Next, the distance estimation response IE determination unit 305 determines whether or not the difference between the proximity counter and the remote counter is less than 3 (S817). If the difference between the proximity counter and the remote counter is not less than 3 and the difference between the proximity counter and the remote counter is 3 or more, it indicates that the value of the proximity counter has been added three times in succession. In such a case, the distance estimation response IE determination unit 305 updates the response information 1 using the response information 2 (S818), and deletes the response information 2 from the memory 309 (S819). Next, the distance estimate response IE determination unit 305 proceeds to step S809 in FIG. 12 and determines that the distance between the AP 101 and the mobile phone 201 has become close.

  In step S817, when the distance estimate response IE determination unit 305 determines that the difference between the proximity counter and the remote counter is less than 3, it determines whether the sum of the proximity counter and the remote counter is 7 or more. (S820). When it is determined that the sum of the proximity counter and the remote counter is not 7 or more and the sum of the proximity counter and the remote counter is less than 7, the distance estimation response IE determination unit 305 deletes the response information 2 from the memory 309. Then, the processing after step S403 in FIG. 7 is repeated. That is, if the distance estimate response IE determination unit 305 determines that the sum of the proximity counter and the remote counter is less than 7, the beacon generation unit does not determine the change in the distance between the AP 101 and the mobile phone 201. 303 transmits the beacon signal in which the distance estimation IE is set again.

  In step S820, when it is determined that the sum of the proximity counter and the remote counter is 7 or more, in order to determine that there is no change in the distance between the AP 101 and the mobile phone 201, step S823 and later described in FIG. Execute the process. Note that the threshold value of the difference between the proximity counter and the remote counter used in step S817 and the threshold value of the sum of the proximity counter and the remote counter used in step S820 can be changed to arbitrary values.

  Next, a case where the distance estimation response IE determination unit 305 determines that the beacon reception strength B is not greater than the beacon reception strength A in step S804 will be described using FIG. When it is determined that the beacon reception strength B is not greater than the beacon reception strength A, the distance estimation response IE determination unit 305 determines whether the beacon reception strength A and the beacon reception strength B are equal (S822). When it is determined that the beacon reception strength A and the beacon reception strength B are equal, the distance estimation response IE determination unit 305 deletes the response information 2 from the memory 309 (S823), and the distance between the AP 101 and the mobile phone 201 does not change. Is determined (S824). That is, the response information 1 remains stored in the memory 309 and is used for the next comparison.

  Next, the distance estimation response IE determination unit 305 initializes the proximity counter and the remote counter (S825). Next, the distance estimate response IE determination unit 305 outputs a determination result indicating that the distance between the AP 101 and the mobile phone 201 is not changed to the display unit or the like via the LED 310 or the wired LAN interface 311 (S826). Thereby, the user having the AP 101 can grasp that there is no change in the distance between the AP 101 and the mobile phone 201.

  Next, when the AP 101 repeatedly executes the process of detecting a change in the distance between the AP 101 and the mobile phone 201, the AP 101 repeats the process of step S403 in FIG. 7 (S827). If the AP 101 does not repeatedly execute the process of detecting the change in the distance between the AP 101 and the mobile phone 201, the process ends (S828).

  Next, the case where the distance estimation response IE determination unit 305 determines that the beacon reception strength A and the beacon reception strength B are not equal in step S822 will be described using FIG. Since it is determined in step S804 that the beacon reception strength B is equal to or less than the beacon reception strength A, the case where it is determined in step S822 that the beacon reception strength A and the beacon reception strength B are not equal, that is, beacon reception. It shows that the intensity B is smaller than the beacon reception intensity A.

  In this case, the distance estimation response IE determination unit 305 determines whether the ProbeReQ transmission output A and the ProbeReQ transmission output B are equal (S829). The ProbeReQ transmission output A is a ProbeReQ transmission output included in the response information 1, and the ProbeReQ transmission output B is a ProbeReQ transmission output included in the response information 2.

  When the ProbeReQ transmission output A and the ProbeReQ transmission output B are different, the distance estimation response IE determination unit 305 corrects the ProbeReQ reception intensity A of the response information 1 (S830). For example, the distance estimation response IE determination unit 305 corrects the ProbeReQ reception intensity A as follows: ProbeReQ reception intensity A after correction = ProbeReQ reception intensity A + before correction (ProbeReQ transmission output B−ProbeReQ transmission output A). For example, if the second ProbeReQ transmission output is 3 dB higher than the first ProbeReQ transmission output performed by the distance estimation IE generation unit 304, the corrected ProbeReQ reception intensity is 3 dB added to the uncorrected ProbeReQ reception intensity A Value.

  When the ProbeReQ transmission output A and the ProbeReQ transmission output B are equal, or when the ProbeReQ reception strength A is corrected, the distance estimation response IE determination unit 305 determines whether the ProbeReQ reception strength A is equal to or higher than the ProbeReQ reception strength B ( S831). When the distance estimate response IE determination unit 305 determines that the ProbeReQ reception strength A is equal to or higher than the ProbeReQ reception strength B, the distance estimation response IE determination unit 305 executes the processing of FIG.

  Next, the case where it is determined in step S831 that the ProbeReQ reception strength A is equal to or higher than the ProbeReQ reception strength B will be described using FIG. In this case, the distance estimate response IE determination unit 305 updates the response information 1 in the memory 309 to the content of the response information 2 (S832). That is, the distance estimation response IE determination unit 305 overwrites the response information 1 in the memory 309 with the content of the response information 2 and deletes the response information 2 from the memory 309.

  Next, the distance estimation response IE determination unit 305 determines that the AP 101 and the mobile phone 201 have moved away (S833). That is, the distance estimation response IE determination unit 305 determines that the AP 101 and the mobile phone 201 have moved away because the beacon reception strength A is greater than the beacon reception strength B and the ProbeReQ reception strength A is greater than or equal to the ProbeReQ reception strength B. To do.

  Next, the distance estimation response IE determination unit 305 initializes the proximity counter and the remote counter (S834). Next, the distance estimation response IE determination unit 305 outputs a determination result that the AP 101 and the mobile phone 201 have moved away to the display unit or the like via the LED 310 or the wired LAN interface 311 (S835). As a result, the user having the AP 101 can recognize that the AP 101 and the mobile phone 201 have moved away.

  Next, when the AP 101 repeatedly executes the process of detecting the change in the distance between the AP 101 and the mobile phone 201, the AP 101 repeats the process of step S403 in FIG. 7 (S836). If the AP 101 does not repeatedly execute the process of detecting the change in the distance between the AP 101 and the mobile phone 201, the process ends (S837).

  Next, the case where it is determined in step S831 that the ProbeReQ reception strength A is smaller than the ProbeReQ reception strength B will be described using FIG.

  In this case, the change in the distance between the AP 101 and the mobile phone 201 assumed from the comparison result of the beacon reception strength is different from the change in the distance between the AP 101 and the mobile phone 201 assumed from the comparison result of the ProbeReQ reception strength. Therefore, the distance estimation response IE determination unit 305 applies the comparison result of the beacon reception strength and determines that there is a possibility that the AP 101 and the mobile phone 201 are far away (S838). Next, the distance estimate response IE determination unit 305 increments the value of the remote counter by 1 (S839). As described above, the distance estimation response IE determination unit 305 determines using a proximity counter or a remote counter when it cannot make a definite determination regarding a change in the distance between the AP 101 and the mobile phone 201.

  Next, the distance estimation response IE determination unit 305 determines whether or not the difference between the proximity counter and the remote counter is less than 3 (S840). If the difference between the proximity counter and the remote counter is not less than 3 and the difference between the proximity counter and the remote counter is 3 or more, it indicates that the value of the remote counter has been added three times in succession. In such a case, the distance estimation response IE determination unit 305 updates the response information 1 using the response information 2 (S841), and deletes the response information 2 from the memory 309 (S842). Next, the distance estimate response IE determination unit 305 proceeds to step S833 in FIG. 16 and determines that the distance between the AP 101 and the mobile phone 201 has increased.

  If the difference between the proximity counter and the remote counter is less than 3 in step S840, the processing after step S820 in FIG. 13 is executed. "

  In steps S815 and S838, the change in the distance between the AP 101 and the mobile phone 201 assumed from the comparison result of the beacon reception strength, and the change in the distance between the AP 101 and the mobile phone 201 assumed from the comparison result of the ProbeReQ reception strength. The case where is different was explained. At this time, the comparison result of the beacon reception strength is applied and it is described as assuming the change in the distance between the AP 101 and the mobile phone 201. However, the comparison result of the ProbeReQ reception strength is applied to the AP 101 and the mobile phone. A change in the distance to the telephone 201 may be assumed.

  As described above, by using the communication system according to the second exemplary embodiment of the present invention, it is determined whether the distance between the AP 101 and the mobile phone 201 is approaching, moving away, or not changing. be able to. Furthermore, even when the transmission intensity (transmission power) of the beacon signal transmitted from the AP 101 changes, the value of the reception intensity of the beacon signal in the mobile phone 201 can be corrected. Furthermore, even when the transmission intensity of the ProbeReQ signal transmitted from the mobile phone 201 changes, the value of the reception intensity of the ProbeReQ signal at the AP 101 can be corrected. Thereby, a change in the distance between the AP 101 and the mobile phone 201 can be accurately detected.

  Further, when the mobile phone 201 receives a beacon signal in which the distance estimation IE is set, the mobile phone 201 autonomously transmits a ProbeReQ signal in which the distance estimation response IE is set. As a result, for example, the location of the mobile phone can be specified or estimated even when an operation by the mobile phone holder is not performed in a disaster or the like. In general, since a mobile phone is often placed near a user of the mobile phone, it is possible to obtain a large clue to find a person by specifying or estimating the location of the mobile phone.

  In an emergency such as a disaster, an upper network such as a communication carrier network is often not usable because the line is narrowed to avoid congestion. Therefore, the ability to specify or estimate the position of a mobile phone in a network composed of only a local wireless LAN can increase the possibility of realizing an early search for missing persons.

  In the above description, the mobile phone 201 is described as an example of the communication destination of the AP 101. However, the mobile phone 201 is not limited to the mobile phone 201 as long as the terminal can perform wireless LAN communication. Further, by using a voice guide with a wireless LAN function used in a museum or the like as a communication destination terminal of the AP 101, it is possible to check the flow of people who have the voice guide in the museum.

  In addition, setting the distance estimation IE in the beacon signal or setting the distance estimation response IE in the ProbeReQ signal when the distance estimation IE is received is realized by using software instead of specific hardware. Therefore, the apparatus can be configured at low cost.

  Moreover, by setting the distance estimation IE and the distance estimation response IE to a beacon signal or a ProbeReQ signal, it is possible to avoid using a radio frame dedicated to distance measurement. For this reason, it is possible to avoid compression of the wireless band, and it is also possible to suppress the power consumption of the apparatus.

(Embodiment 3)
Next, the flow of beacon signal transmission processing according to Embodiment 3 of the present invention will be described using FIG. Steps S1001 to S1004 are the same as steps S401 to S404 in FIG. When the beacon generation unit 303 generates the distance estimate IE in step S1004, the beacon generation unit 303 determines whether or not a predetermined time has elapsed since the beacon signal in which the distance estimate IE was set last time (S1005).

  If the beacon generation unit 303 determines that a predetermined time has not elapsed since the previous transmission of the beacon signal in which the distance estimation IE is set, the beacon signal is transmitted without setting the distance estimation IE as a beacon signal ( S1008). If the beacon generation unit 303 determines that a predetermined time has elapsed since the transmission of the beacon signal in which the distance estimation IE is set last time, the beacon generation unit 303 performs the processes of steps S1006 to S1008. Steps S1006 to S1008 are the same as steps S405 to S407 in FIG.

  As described above, by executing the beacon signal transmission process in FIG. 18, the number of times the ProbeReQ signal is transmitted in the mobile phone 201 can be suppressed. As a result, it is possible to avoid compression of the wireless band, and it is possible to realize a reduction in power consumption of the mobile phone 201.

(Embodiment 4)
Subsequently, the distance estimation IE according to the fourth embodiment of the present invention will be described with reference to FIG. In the distance estimation IE of this figure, information on the request target MAC address is added to the distance estimation IE of FIG. The request target MAC address is the MAC address of the mobile phone that is desired to be searched. As described above, by setting the request target MAC address, a terminal that should respond to the beacon signal in which the distance estimation IE is set may be specified.

  Next, the flow of the ProbeReQ signal transmission process when the distance estimation IE of FIG. 19 is used will be described with reference to FIG. Steps S1101 and S1102 are the same as steps S601 and S602 in FIG.

  When the mobile phone 201 determines that the distance estimate IE is set in the beacon signal, the mobile phone 201 determines whether or not the request target MAC address set in the distance estimate IE matches the MAC address of its own device. To do. If the mobile phone 201 determines that the MAC addresses match, the mobile phone 201 executes the processing from step S1104 onward. Steps S1104 to S1108 are the same as steps S604 to S608 in FIG. If the mobile phone 201 determines that the MAC addresses do not match, the mobile phone 201 ends the process.

  As described above, as shown in FIG. 19, the mobile phone 201 to be searched can be specified by setting the request target MAC address in the distance estimation IE. As a result, the cellular phone 201 having a MAC address different from the request target MAC address does not transmit the ProbeReQ signal in which the distance estimation response IE is set, thereby avoiding compression of the wireless band used in the wireless LAN. Can do. In addition, since mobile phones other than the mobile phone 201 to be searched do not respond, power consumption can be suppressed.

  In the above-described embodiments, the present invention has been described as a hardware configuration, but the present invention is not limited to this. The present invention can also realize processing in the wireless communication apparatus or AP by causing a CPU (Central Processing Unit) to execute a computer program. )

  In the above example, the program can be stored and supplied to a computer using various types of non-transitory computer readable media. Non-transitory computer readable media include various types of tangible storage media. Examples of non-transitory computer-readable media include magnetic recording media (for example, flexible disks, magnetic tapes, hard disk drives), magneto-optical recording media (for example, magneto-optical disks), CD-ROMs (Read Only Memory), CD-Rs, CD-R / W, semiconductor memory (for example, mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, RAM (Random Access Memory)) are included. The program may also be supplied to the computer by various types of transitory computer readable media. Examples of transitory computer readable media include electrical signals, optical signals, and electromagnetic waves. The temporary computer-readable medium can supply the program to the computer via a wired communication path such as an electric wire and an optical fiber, or a wireless communication path.

  Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention.

(Supplementary Note 1) Information on the reception strength of the first and second radio signals measured in the search target device and a transmission unit that transmits the first and second radio signals to the search target device. And the first and second radios based on the transmission powers in the first and second radio signals when the transmission power in the first and second radio signals is in a specific situation. A processing unit that corrects at least one of the reception strengths of the signals and detects a change in the distance to the searched device in accordance with the reception strengths of the first and second radio signals after correction. Wireless communication device.
(Additional remark 2) The said process part receives the response signal regarding the said 1st and 2nd radio | wireless signal from the said to-be-searched apparatus, The reception intensity | strength of the said response signal, and the said 1st and said measured by the to-be-searched apparatus The wireless communication device according to appendix 1, wherein a change in the distance to the search target device is detected according to the reception strength of the second wireless signal.
(Additional remark 3) The said transmission part sets the information element which shows that it is a radio signal used in order to detect the change of the distance between the said to-be-searched devices to the said 1st and 2nd radio signal. The wireless communication device according to 1 or 2.
(Additional remark 4) The said receiving part is set when the said to-be-searched apparatus transmits the response signal regarding the said 1st and 2nd radio signal and the information regarding the receiving strength of the said 1st and 2nd radio signal. The wireless communication device according to any one of appendices 1 to 3, wherein the response signal in which an information element in which information related to power is set is received is received.
(Supplementary Note 5) The transmission unit transmits the second wireless signal to the searched device after transmitting the first wireless signal to the searched device, and the receiving unit transmits the first wireless signal of the first wireless signal. After receiving the information on the reception strength, the information on the reception strength of the second radio signal is received, and the processing unit receives the reception strength of the second radio signal higher than the reception strength of the first radio signal. When the reception strength of the response signal related to the second wireless signal transmitted from the searched device is larger than the received strength of the response signal related to the first wireless signal transmitted from the searched device The wireless communication device according to any one of appendices 1 to 4, wherein the wireless communication device determines that the distance to the search target device is short.
(Additional remark 6) The said process part is larger than the receiving intensity of the said 1st radio signal, and the response signal regarding the said 2nd radio signal transmitted from the said to-be-searched apparatus is the said 2nd radio signal receiving intensity. The wireless communication according to appendix 5, wherein when the received strength of the received signal is smaller than the received strength of the response signal related to the first wireless signal transmitted from the searched device, it is estimated that the distance to the searched device is close apparatus.
(Supplementary note 7) The transmission unit transmits a first radio signal in which an information element indicating a radio signal used for detecting a change in the distance to the searched device is transmitted for a predetermined period of time. 4. The wireless communication device according to appendix 3, wherein after the elapse of time, a second wireless signal in which an information element indicating a wireless signal used for detecting a change in distance to the search target device is set is transmitted.
(Supplementary note 8) In any one of Supplementary notes 1 to 7, wherein the transmission unit transmits the first and second wireless signals in which the identifier of the searched device is set to a plurality of wireless terminal devices existing in the vicinity. The wireless communication device described.
(Supplementary Note 9) When a wireless signal in which an information element indicating that a change in the distance between the searched device and the wireless communication device is detected is received, between the searched device and the wireless communication device A searched device that sets information used for detecting a change in distance as a response signal to the wireless signal and transmits the information to the wireless communication device.
(Supplementary Note 10) The first and second radio signals are transmitted to the searched device, and information on the reception strengths of the first and second wireless signals measured in the searched device is received from the searched device. It is determined whether or not there is a difference in transmission power between the first and second radio signals, and when there is a difference in transmission power between the first and second radio signals, the first and second radio signals The received power of at least one of the first and second radio signals is corrected using a difference in transmission power between the signals, and the search target is performed according to the corrected received power of the first and second radio signals. A device search method for detecting a change in the distance to a device.
(Supplementary Note 11) The first and second radio signals are transmitted to the searched device, and information on the reception strengths of the first and second wireless signals measured in the searched device is received from the searched device. It is determined whether or not there is a difference in transmission power between the first and second radio signals, and when there is a difference in transmission power between the first and second radio signals, the first and second radio signals The received power of at least one of the first and second radio signals is corrected using a difference in transmission power between the signals, and the search target is performed according to the corrected received power of the first and second radio signals. A program that causes a computer to detect a change in the distance to a device.

DESCRIPTION OF SYMBOLS 10 Wireless communication apparatus 11 Transmission part 12 Reception part 13 Processing part 20 Searched apparatus 101 AP
201 mobile phone 202 mobile phone interface 203 wireless LAN interface 302 wireless LAN interface 303 beacon generation unit 304 distance estimation IE generation unit 305 distance estimation response IE determination unit 306 proximity counter 307 remote counter 308 reception unit 309 memory 310 LED
311 Wired LAN interface

Claims (8)

A transmission unit for transmitting the first and second radio signals to the searched device;
A receiving unit that receives from the searched device information related to the reception strength of the first and second radio signals measured in the searched device;
When the transmission strength of the first and second radio signals is in a specific situation, reception of at least one of the first and second radio signals based on the transmission strength of the first and second radio signals The first and second radio signals are corrected by detecting a first change in the distance to the searched device in accordance with the received intensity of the first and second radio signals after correction. A response signal for the search target device, and depending on the reception strength of the response signal and the reception strength of the first and second radio signals measured by the search target device, And a processing unit that detects a second change in the distance between the wireless communication devices. The transmitter is
An information element indicating that the wireless signal is used for detecting at least one of a first change and a second change in distance to the search target device is set in the first and second wireless signals. Item 2. The wireless communication device according to Item 1 . The receiver is
An information element in which information on the reception strength of the first and second radio signals and information on the transmission strength set when the searched device transmits a response signal on the first and second radio signals are set. The wireless communication device according to claim 1, wherein the response signal in which is set is received. The transmitter is
After transmitting the first wireless signal to the searched device, the second wireless signal is transmitted to the searched device,
The receiver is
After receiving information on the reception strength of the first radio signal, receiving information on the reception strength of the second radio signal;
The processor is
The reception strength of the second radio signal is greater than the reception strength of the first radio signal, and the reception strength of the response signal related to the second radio signal transmitted from the search target device is the search target. The wireless communication according to any one of claims 1 to 3 , wherein when the response intensity of the response signal related to the first wireless signal transmitted from the device is larger than the reception strength, it is determined that the distance to the search target device has approached. apparatus. The processor is
The received intensity of the second radio signal is greater than the received intensity of the first radio signal, and the received intensity of the response signal related to the second radio signal transmitted from the searched apparatus is the searched apparatus. The wireless communication device according to claim 4, wherein the wireless communication device estimates that the distance to the search target device has approached when the received signal strength of the response signal related to the first wireless signal transmitted from is smaller. The transmitter is
A predetermined period after transmitting the first radio signal in which the information element indicating the radio signal is used for detecting at least one of the first and second changes in the distance to the search target device. A second wireless signal in which an information element indicating that the wireless signal is used for detecting at least one of the first and second changes in the distance to the search target device is set after the elapse of time; The wireless communication apparatus according to claim 2 . Transmitting the first and second radio signals to the searched device;
Receiving information on the reception strength of the first and second radio signals measured in the searched device from the searched device;
It is determined whether there is a difference in transmission strength between the first and second radio signals, and when there is a difference in transmission strength between the first and second radio signals, the first and second radio signals Correcting the reception strength of at least one of the first and second radio signals using the difference in transmission strength in
A first change in the distance to the search target device is detected according to the reception strength of the first and second radio signals after correction, and a response signal related to the first and second radio signals is detected as the response signal. The distance between the search target device and the search target device is determined according to the reception strength of the response signal received from the search target device and the reception strength of the first and second radio signals measured by the search target device. A device search method for detecting a second change . Transmitting the first and second radio signals to the searched device;
Receiving information on the reception strength of the first and second radio signals measured in the searched device from the searched device;
It is determined whether there is a difference in transmission strength between the first and second radio signals, and when there is a difference in transmission strength between the first and second radio signals, the first and second radio signals Correcting the reception strength of at least one of the first and second radio signals using the difference in transmission strength in
A first change in the distance to the search target device is detected according to the reception strength of the first and second radio signals after correction, and a response signal related to the first and second radio signals is detected as the response signal. The distance between the search target device and the search target device is determined according to the reception strength of the response signal received from the search target device and the reception strength of the first and second radio signals measured by the search target device. A program that causes a computer to detect the second change .

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