JP2011078015A - Communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication system capable of accurately determining a distance between radio devices based on a strength of a receiving signal even under a multi-path environment. <P>SOLUTION: Each of base stations 1-16 refers to a distance identification function indicating a distribution in distances of receiving signal strengths previously measured under a multi-path environment to calculate certainty (=probability) of distances between the base stations 1-16 and radio devicees 21-30 corresponding to a receiving signal strength detected when identifying the distances. The distance corresponding to such a distance identification function as to obtain the maximum certainty (=probability) is detected as an identification distance between the base stations 1-16 and the radio devices 21-30. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a communication system, and more particularly to a communication system capable of determining the position of each wireless device.

  2. Description of the Related Art Conventionally, a communication system that can detect a wireless module close to a certain wireless module is known (Patent Document 1).

  In this communication system, each wireless module detects the received signal strength when receiving radio waves from other wireless modules, and based on the detected received signal strength, the distance between itself and the other wireless module. Is calculated.

  Each wireless module detects another wireless module as a proximity wireless module if the calculated distance is equal to or less than a reference value (= 3 m).

JP 2006-352518 A

  However, in the conventional communication system, each wireless module calculates the distance from the other wireless module based on the received signal strength when the radio wave is received from the other wireless module. There is a problem that it is difficult to accurately calculate the distance to the module.

  That is, when radio waves propagate via multipath, the received signal strength is distributed over a wide range, so there may be multiple received signal strengths for one distance between two wireless modules. It is difficult to accurately calculate the distance between two wireless modules.

  Accordingly, the present invention has been made to solve such a problem, and an object of the present invention is to provide a communication system capable of accurately determining the distance between wireless devices based on received signal strength even in a multipath environment. It is to be.

  According to the present invention, the communication system includes a plurality of first wireless devices and a plurality of second wireless devices. Each of the plurality of first wireless devices transmits radio waves by wireless communication in one room of an arbitrary building. Each of the plurality of second wireless devices receives radio waves transmitted from the plurality of first wireless devices in one room. Each of the plurality of second wireless devices is transmitted from one first wireless device when the distance between the first wireless device and one first wireless device is set to one distance in one room. A distance identification function indicating the relationship between the received signal strength when receiving a received radio wave and the degree of distribution of the received signal strength is stored in advance in association with a plurality of distances to one first wireless device. When receiving a radio wave from any one of the plurality of first radio apparatuses, the received signal strength when the radio wave is received is detected, and a plurality of distance identifications held in association with the plurality of distances Referring to the function, the first maximum distribution degree, which is the maximum distribution degree among the distribution degrees corresponding to the detected received signal strength, is detected, and the distance from which the detected first maximum distribution degree is obtained The distance corresponding to the discriminant function is the first and the first Performing the first wireless device a process of detecting as identification distance plurality between line unit.

  Preferably, each of the plurality of second wireless devices receives Q (Q is a positive integer) number of radio waves from any one of the first wireless devices within a predetermined time, and receives Q number of radio waves. An average of the Q received signal strengths is detected as the received signal strength.

  Preferably, each of the plurality of second wireless devices further includes a first identification for identifying the second wireless device based on a result of weighting and combining the plurality of distance identification functions according to a predetermined first rule. Calculate as a function.

  Preferably, each of the plurality of second wireless devices periodically calculates an identification function for identifying the second wireless device, and H calculated at H (H is an integer of 2 or more) consecutive timings. Is calculated as the first discriminant function.

  Preferably, the communication system further includes a communication device. The communication device receives the detected received signal strength, the plurality of identification distances, and the plurality of first identification functions from the plurality of second wireless devices arranged in one room, and the received plurality of first devices A second radio arranged in a plurality of rooms for calculating a result obtained by weighting and combining one identification function according to a predetermined second rule as a second identification function for identifying a room in the building A plurality of first discriminant functions received from the device are executed, and based on the calculated second discriminant functions, corresponding to received signal strengths received from the second radio devices arranged in the plurality of rooms. A second maximum distribution degree which is the maximum distribution degree among the plurality of distribution degrees is detected, and a room corresponding to the second discriminant function from which the detected second maximum distribution degree is obtained is assigned to a plurality of second distribution functions. Room where one wireless device stays One first radio based on the received signal strength, the plurality of identification distances, and the plurality of first identification functions received from the plurality of second radio apparatuses arranged in the determined room. Detecting a third maximum distribution degree which is a maximum distribution degree among a plurality of distribution degrees corresponding to a plurality of received signal strengths when radio waves transmitted from the apparatus are received by a plurality of second wireless devices; The second wireless device that has transmitted the first identification function that has obtained the detected third maximum distribution degree is determined as the second wireless device that is closest to one first wireless device, and the closest first The process of determining the position of one first wireless device based on the identification distance received from the two wireless devices is executed for the plurality of first wireless devices.

  Preferably, the communication apparatus further executes a process of calculating a first reliability, which is a reliability of the closest second wireless apparatus, for all of the plurality of first wireless apparatuses, and calculates the calculated first reliability. Using the figure whose size increases as the degree increases, the calculated plurality of reliability levels are displayed as visual information together with the positions of the plurality of first wireless devices.

  Preferably, the plurality of second wireless devices are arranged in one hospital room corresponding to a plurality of beds in one hospital room. The plurality of first wireless devices are attached to doctors and nurses in the hospital.

  Preferably, when the first reliability is equal to or higher than the first threshold value, the communication device selects a patient in a bed corresponding to the closest second wireless device as a patient to be a subject of nursing records.

  Preferably, when the first reliability is lower than the first threshold, the communication device selects a patient who is a subject of nursing records from all patients in a room where the closest second wireless device is arranged. .

  Preferably, the communication device further executes a process of calculating a second reliability, which is a reliability of a room where the plurality of first wireless devices stay, for all of the plurality of first wireless devices, Is adjacent to the room where the nearest second wireless device is located and the room when the second reliability is lower than the first threshold and the second reliability is lower than the second threshold. Select patients for nursing records from all patients in both rooms.

  Preferably, the communication device further transmits the determined positions of the plurality of first wireless devices to the information communication system installed in the hospital.

  In the communication system according to the present invention, the second radio apparatus refers to a distance discrimination function indicating a distribution of reception signal strengths measured in advance in a multipath environment at each distance, and receives signal strength detected at the time of distance discrimination. The probability (= probability) of the distance between the second wireless device and the first wireless device corresponding to is obtained, and the distance corresponding to the distance identification function that obtains the maximum probability (= probability) is determined as the second. This is detected as an identification distance between the wireless device and the first wireless device.

  As a result, as the degree of deviation between the received signal strength detected at the time of identifying the identification distance and the received signal strength at which the distribution of the received signal strength measured in advance is maximized, the distance identification function is supported. The certainty with respect to the distance is reduced. On the other hand, the distance corresponding to the distance identification function becomes smaller as the degree of deviation between the received signal strength detected when identifying the identification distance and the received signal strength at which the distribution of received signal strength measured in advance is maximized. The certainty with respect to increases.

  Therefore, even if the distance between the second radio apparatus and the first radio apparatus is detected using the received signal strength detected in the multipath environment, the influence due to the fluctuation of the received signal strength is removed and the first radio apparatus is removed. The distance between the two wireless devices and the first wireless device can be accurately detected.

1 is a schematic diagram of a communication system according to an embodiment of the present invention. It is a schematic block diagram which shows the structure of the base station shown in FIG. It is a schematic block diagram which shows the structure of the server shown in FIG. It is a figure for demonstrating the method of calculating | requiring a distance discrimination function. It is a figure which shows the measurement result of received signal strength. It is a conceptual diagram of a Gaussian distribution. It is a conceptual diagram of various distribution. It is a figure which shows the reception timing of a response signal (= FHS packet). It is a figure for demonstrating the method to identify the distance of each base station and each radio | wireless apparatus. It is a figure which shows the example of the weight when calculating | requiring a base station identification function. It is a conceptual diagram of a base station identification function. It is a block diagram of a reception buffer. It is a figure which shows the memory | storage form of the data in the receiving buffer shown in FIG. It is a flowchart for demonstrating the operation | movement in a base station. It is a flowchart for demonstrating the detailed operation | movement of step S6 shown in FIG. It is a flowchart for demonstrating the reception process of a server. It is a flowchart for demonstrating the position detection process of a server. It is a flowchart for demonstrating the detailed operation | movement of step S28 shown in FIG. It is a figure which shows the other example of the weight when calculating | requiring a base station identification function. It is a figure which shows the further another example of the weight when calculating | requiring a base station identification function.

  Embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 1 is a schematic diagram of a communication system according to an embodiment of the present invention. Referring to FIG. 1, a communication system 100 according to an embodiment of the present invention includes base stations 1 to 16, radio apparatuses 21 to 30, and a server 40. The communication system 100 is installed in a medical institution such as a hospital, for example.

  Base stations 1 to 4 are installed in a hospital room R1. Base stations 5 to 8 are installed in a hospital room R2. The base stations 9 to 12 are installed in a hospital room R3. The base stations 13 to 16 are installed in the hospital room R4.

  More specifically, each of the base stations 1 to 4 is installed close to the beds BD1 to BD4 installed in the room R1. In addition, the base stations 5 to 8 are installed in the vicinity of the beds BD5 to BD8 installed in the room R2, respectively. Further, the base stations 9 to 12 are installed in proximity to the beds BD9 to BD12 installed in the room R3, respectively. Further, the base stations 13 to 16 are installed in proximity to the beds BD13 to BD16 installed in the room R4, respectively.

  Persons working in medical institutions such as hospital doctors, nurses, and technicians (e.g., radiographers) carry the wireless devices 21-30. Therefore, the wireless devices 21 to 30 move in the hospital as doctors, nurses, and technicians move in the hospital. In the case illustrated in FIG. 1, the wireless devices 21 to 23 are located in the room R1, the wireless devices 24 to 26 are located in the room R2, and the wireless devices 27 and 28 are located in the room R3. 29 and 30 are located in the room R4.

  The server 40 is installed in the nurse station NS. The server 40 is connected to the base stations 1 to 16 by a wired cable (not shown).

  The rooms R1 and R2 are respectively disposed on the opposite sides of the rooms R3 and R4 with the hallway CRD1 interposed therebetween. The nurse station NS is arranged on the opposite side of the room R1 across the hallway CRD2.

  The room R1 is adjacent to the room R2 with the wall WL1 interposed therebetween, and the room R3 is adjacent to the room R4 with the wall WL2 interposed therebetween.

  The base stations 1 to 16 perform wireless communication with the wireless devices 21 to 30 according to the Bluetooth standard.

  More specifically, the base stations 1 to 16 transmit (broadcast) an inquiry signal to the surroundings using a Bluetooth standard inquiry state, and receive a response signal to the inquiry signal from the wireless devices 21 to 30. To do. Then, the base stations 1 to 16 detect the received signal strength of the received response signal, and identify the distance between the wireless devices 21 to 30 based on the detected received signal strength by a method described later. The identified identification distance is detected.

  Further, the base stations 1 to 16 calculate an identification function for identifying a base station (any one of the base stations 1 to 16) closest to each of the radio apparatuses 21 to 30 by a method described later.

  The base stations 1 to 16 transmit the identifiers of the wireless devices 21 to 30, the received signal strength of the response signals received from the wireless devices 21 to 30, the identification distance from the wireless devices 21 to 30, and the identification function to the wired cable (see FIG. (Not shown) to the server 40.

  The wireless devices 21 to 30 perform wireless communication with the base stations 1 to 16 in accordance with the Bluetooth standard.

  More specifically, when the wireless devices 21 to 30 receive the Bluetooth standard inquiry signal from the base station (any of the base stations 1 to 16), the wireless devices 21 to 30 generate a response signal to the received inquiry signal and generate the response signal. A response signal is transmitted to the base station (any one of the base stations 1 to 16).

  The server 40 wired the identifier of the wireless devices 21 to 30, the received signal strength of the response signal received from the wireless devices 21 to 30, the identification distance between the base stations 1 to 16 and the wireless devices 21 to 30, and the identification function. Receiving from each of the base stations 1 to 16 via a cable (not shown).

  And the server 40 is the identifier of the received radio | wireless apparatuses 21-30, the received signal strength of the response signal received from the radio | wireless apparatuses 21-30, the identification distance between the base stations 1-16 and the radio | wireless apparatuses 21-30, Based on the discriminant function, it is determined which position in which room each of the wireless devices 21 to 30 is present by a method described later.

  FIG. 2 is a schematic block diagram showing the configuration of the base station 1 shown in FIG. Referring to FIG. 2, base station 1 includes a wireless module 110 and an embedded CPU 120.

  The wireless module 110 includes a protocol management unit 111, a transmission processing unit 112, a wireless unit 113, and a reception processing unit 114.

  The protocol management unit 111 generates an inquiry transmission instruction (Inquiry transmission instruction) and an inquiry response instruction (Inquiry Scan instruction) according to control from the microcomputer 121 of the embedded CPU 120 and outputs the inquiry transmission instruction (Inquiry Scan instruction) to the transmission processing unit 112.

  Further, the protocol management unit 111 receives an FHS packet, which will be described later, and a received signal strength RSSI of the FHS packet from the reception processing unit 114. Then, the protocol management unit 111 detects the address of the wireless device (any of the wireless devices 21 to 30) that transmitted the FHS packet from the received FHS packet, and receives the detected address and the reception processing unit 114 from the received address. The received signal strength RSSI is transmitted to the microcomputer 121.

  The transmission processing unit 112 periodically generates an inquiry signal (= IQ packet) for inquiring whether there is a wireless device around the base station 1 in response to an inquiry transmission command from the protocol management unit 111. The periodically generated IQ packet is output to the wireless unit 113.

  Further, the transmission processing unit 112 generates a response signal (= FHS packet) corresponding to the inquiry signal (= IQ packet) received from the wireless device in response to the inquiry response command from the protocol management unit 111 to generate the wireless unit 113. Output to.

  The wireless unit 113 transmits and receives packets by spread spectrum. More specifically, the wireless unit 113 employs a frequency hopping method with a speed of 1600 times / second, and converts the information modulation signal (1 MHz) to 79 channels (1 MHz / channel) within the band of 2402 to 2481.5 MHz. Hopping and spread modulation to 79 MHz band. The wireless unit 113 transmits and receives the spread modulated packet.

  Upon receiving the IQ packet from the transmission processing unit 112, the wireless unit 113 transmits the received IQ packet by frequency hopping according to the inquiry hopping sequence. More specifically, the wireless unit 113 transmits an IQ packet by frequency hopping to 32 channels or 16 channels within a band of 2402 to 2481.5 MHz.

  Further, upon receiving the FHS packet from the transmission processing unit 112, the wireless unit 113 transmits the received FHS packet by frequency hopping according to the response sequence. More specifically, the wireless unit 113 transmits the FHS packet by frequency hopping to 32 channels or 16 channels within a band of 2402 to 2481.5 MHz.

  Further, the wireless unit 113 receives an IQ packet from the wireless device and outputs the received IQ packet to the reception processing unit 114.

  When receiving the IQ packet from the wireless unit 113, the reception processing unit 114 detects the received signal strength RSSI of the received IQ packet. Then, the reception processing unit 114 despreads the IQ packet, and outputs the IQ packet after the spectrum despreading and the detected received signal strength RSSI to the protocol management unit 111.

  The embedded CPU 120 includes a microcomputer 121 and a storage device 122. The microcomputer 121 controls the protocol management unit 111 of the wireless module 110 so as to start or interrupt the inquiry transmission, and controls the protocol management unit 111 so as to start or interrupt the inquiry response.

  Further, the microcomputer 121 receives the address and the received signal strength RSSI from the protocol management unit 111. The microcomputer 121 stores the received address and received signal strength RSSI in the storage device 122 in association with each other.

  In this case, if the microcomputer 121 receives the address and the received signal strength RSSI from the protocol management unit 111, the microcomputer 121 sets the received address and the received signal strength RSSI even if the received address is the same as the already received address. The data is sequentially stored in the storage device 122.

  Furthermore, when the distance between the base station 1 and one wireless device (any of the wireless devices 21 to 30) is set to a known distance, the microcomputer 121 receives a response signal (= A distance identification function indicating the relationship between the received signal strength RSSI when the FHS packet is received and the degree of distribution of the received signal strength RSSI is read from the storage device 122 and associated with the addresses of the wireless devices 21 to 30. The received signal strength RSSI is read from the storage device 122.

  Then, the microcomputer 121 identifies the distance between the base station 1 and the wireless device (any of the wireless devices 21 to 30) by a method described later based on the read distance identification function and the received signal strength RSSI. Then, the identified identification distance is detected.

  Further, the microcomputer 121 uses a method described later on the basis of a distance identification function associated with each distance between the base station 1 and the wireless device (any of the wireless devices 21 to 30). Any of the devices 21 to 30) calculates a base station identification function that identifies the degree of proximity to the base station 1.

  The microcomputer 121 receives the address of the wireless device (any of the wireless devices 21 to 30) and the received signal strength RSSI when the response signal (FHS packet) is received from the wireless device (any of the wireless devices 21 to 30). The identification distance between the base station 1 and the wireless device (any of the wireless devices 21 to 30) and the base station identification function are transmitted to the server 40 via a wired cable (not shown).

  The storage device 122 stores the addresses of the wireless devices 21 to 30 in association with the received signal strength RSSI.

  In addition, the storage device 122 stores a distance identification function in association with each distance between the base station 1 and the wireless device (any of the wireless devices 21 to 30).

  Each of base stations 2 to 16 and radio apparatuses 21 to 30 shown in FIG. 1 has the same configuration as base station 1 shown in FIG.

  FIG. 3 is a schematic block diagram showing the configuration of the server 40 shown in FIG. Referring to FIG. 3, server 40 includes a receiving unit 41, a storage device 42, a processing unit 43, and a display unit 44.

  The reception unit 41 includes a packet PKT = [Addm / wireless device address / reception signal] including data including a wireless device address, reception signal strength, identification distance, and base station identification function, and addresses of the base stations 1 to 16. Strength / identification distance / base station identification function] (m = 1 to 16) is received via a wired cable (not shown).

  Then, the receiving unit 41 extracts the address Addm, the address of the wireless device, the received signal strength, the identification distance, and the base station identification function from the packet PKT, and the extracted address Addm, the address of the wireless device, the received signal strength, the identification The distance and the base station identification function are stored in the storage device 42 in association with each other.

  The storage device 42 stores the address Addm, the address of the wireless device, the received signal strength, the identification distance, and the base station identification function in association with each other.

  The storage device 42 stores the hospital room R1 and the addresses Add1 to Add4 of the base stations 1 to 4 in association with each other, and stores the hospital room R2 and the addresses Add5 to Add8 of the base stations 5 to 8 with each other. The hospital room R3 and the addresses Add9 to Add12 of the base stations 9 to 12 are stored in association with each other, and the hospital room R4 and the addresses Add13 to Add16 of the base stations 13 to 16 are mutually stored. Is stored in association with.

  Further, the storage device 42 stores the processing result by the processing unit 43.

  The processing unit 43 reads the address Addm, the address of the wireless device, the received signal strength, the identification distance, and the base station identification function from the storage device 42, and the read address Addm, the address of the wireless device, the received signal strength, the identification distance, and the base Based on the station identification function, it is periodically determined at which position in which room of the hospital each wireless device 21-30 is present by a method described later. Then, the processing unit 43 outputs the determination result to the display unit 44.

  The display unit 44 displays the processing result by the processing unit 43.

  FIG. 4 is a diagram for explaining a method for obtaining a distance discrimination function. With reference to FIG. 4, the base station 1 is installed in, for example, a room R1. And one radio | wireless apparatus (any of the radio | wireless apparatuses 21-30) is arrange | positioned in the position P11. The position P11 is a position away from the base station 1 by 1 m.

  The radio apparatus installed at the position P11 sequentially transmits a plurality of FHS packets to the base station 1 using an omnidirectional antenna. Then, the base station 1 sequentially detects a plurality of received signal strengths RSSI when sequentially receiving a plurality of FHS packets. Thereafter, the base station 1 detects the detected distribution of the plurality of received signal strengths RSSI as a Gaussian distribution.

  Subsequently, the wireless device is installed at the position P21. The position P21 is a position away from the base station 1 by 3 m.

  Similarly, the wireless device installed at the position P21 sequentially transmits a plurality of FHS packets to the base station 1 using an omnidirectional antenna. Then, the base station 1 sequentially detects a plurality of received signal strengths RSSI when sequentially receiving a plurality of FHS packets. Thereafter, the base station 1 detects the detected distribution of the plurality of received signal strengths RSSI as a Gaussian distribution.

  Subsequently, the wireless device is installed at the position P31. The position P31 is a position away from the base station 1 by 6 m. Similarly, the wireless device installed at the position P31 sequentially transmits a plurality of FHS packets to the base station 1 using an omnidirectional antenna. Then, the base station 1 sequentially detects a plurality of received signal strengths RSSI when sequentially receiving a plurality of FHS packets. Thereafter, the base station 1 detects the detected distribution of the plurality of received signal strengths RSSI as a Gaussian distribution.

  In this way, wireless devices are installed at positions P11, P21, and P31 that are separated by 1m, 3m, and 6m from the base station 1 in the front direction of the base station 1, and a plurality of FHS packets are transmitted from the wireless device to the base station 1. A plurality of received signal strength RSSIs of the FHS packet are detected, and a distribution of the detected received signal strengths RSSI is detected.

  FIG. 5 is a diagram showing the actual measurement result of the received signal strength. FIG. 6 is a conceptual diagram of a Gaussian distribution. Referring to FIG. 5, when the distance between base station 1 and the wireless device is 1 m, received signal strength RSSI is distributed in a range of about −70 dBm to −57 dBm. The number of actually measured received signal strength RSSIs is 227.

  When the distance between the base station 1 and the wireless device is 3 m, the received signal strength RSSI is distributed in a range of about −75 dBm to −62 dBm. The actually measured number of received signal strengths RSSI is 219.

  Furthermore, when the distance between the base station 1 and the wireless device is 6 m, the received signal strength RSSI is distributed in a range of about −90 dBm to −65 dBm. The number of actually measured received signal strength RSSIs is 246.

  As a result, when the distance between the base station 1 and the wireless device is 1 m, the distribution DB1 of the received signal strength RSSI is obtained. When the distance between the base station 1 and the wireless device is 3 m, the distribution of the received signal strength RSSI is obtained. When DB2 is obtained and the distance between the base station 1 and the radio apparatus is 6 m, a distribution DB3 of received signal strength RSSI is obtained.

Then, in each of the distributions DB1 to DB3, the average μ and the variance σ ² are calculated, and the Gaussian distribution is calculated for the distances 1 m, 3 m, and 6 m between the base station 1 and the wireless device.

  As a result, Gaussian distributions GD1 to GD3 are obtained from the distributions DB1 to DB3, respectively. The Gaussian distributions GD1 to GD3 have averages μ1 to μ3, respectively.

  The Gaussian distribution GD1 represents the probability (= probability) that the distance between the base station 1 and the wireless device corresponding to each received signal strength RSSI is 1 m. Similarly, the Gaussian distribution GD2 represents the probability (= probability) that the distance between the base station 1 and the radio apparatus corresponding to each received signal strength RSSI is 3 m, and the Gaussian distribution GD3 corresponds to each received signal strength RSSI. This represents the probability (= probability) that the distance between the base station 1 and the wireless device is 6 m.

  Accordingly, the Gaussian distributions GD1 to GD3 are distance identification functions for identifying the distance between the base station 1 and the wireless device.

The Gaussian distributions GD1 to GD3 are calculated in advance by the method described above, and the distance discriminating functions P1 (x | μ, σ ² ) to P3 (x | μ, σ ² ) composed of the calculated Gaussian distributions GD1 to GD3 are Respectively stored in the storage device 122 of the base station 1 in association with the distances of 1 m, 3 m, and 6 m. Here, x is a random variable.

The distance discriminating functions P1 (x | μ, σ ² ) to P3 (x | μ, σ ² ) are expressed by the equations (1) to (3), respectively.

Referring to FIG. 4 again, in the above description, it has been described that the wireless device is installed at the positions P11, P21, and P31 in the front direction of the base station 1 and the distribution of the received signal strength RSSI in the base station 1 is detected. In the embodiment of the present invention, not limited to this, a wireless device is installed at the positions P11 to P15, P21 to P25, and P31 to P35, and the distribution of the received signal strength RSSI in the base station 1 is detected and detected. The distance identification functions P1 (x | μ, σ ² ) to P3 (x | μ, σ ² ) may be calculated by the method described above based on the distribution of the received signal strength RSSI.

  FIG. 7 is a conceptual diagram of various distributions. In the above description, the distribution of the received signal strength RSSI is detected as a Gaussian distribution. However, in the embodiment of the present invention, the distribution of the received signal strength RSSI is not limited to the triangular distribution ((( a)), uniform distribution (see (b) of FIG. 7), multinomial distribution (see (c) of FIG. 7), and multimodal distribution (see (d) of FIG. 7). In general, any distribution may be used as long as the function f (x) satisfies the condition as a probability distribution. Here, the condition as the probability distribution is f (x) ≧ 0, and when f (x) is integrated in the range of x = −∞ to + ∞, the integrated value becomes “1”. It is.

When the base station 1 is installed at substantially the center of one wall of the room R1, the distance discrimination functions P1 (x | μ, σ ² ) to P3 (x | μ, σ ² ) are calculated for each distance. As described above, actually, the base station 1 is installed at the installation position of the base station 1 in the room R1 shown in FIG. 1, and the distance discrimination functions P1 (x | μ, σ ² ) to P3 ( x | μ, σ ² ) is calculated. The same applies to the base stations 2 to 16.

Accordingly, the distance discrimination functions P1 (x | μ, σ ² ) to P3 (x | μ, σ ² ) stored in the storage devices 122 of the base stations 1 to 16 are different from each other.

A method for identifying the distance between each base station 1-16 and each wireless device 21-30 will be described. FIG. 8 is a diagram illustrating the reception timing of the response signal (= FHS packet). In FIG. 8, the FHS packet received qth (q is a positive integer) th from the wireless device s (s = 21-30) in the period t ^(m) of the base station m (m = 1-16). The received signal strength RSSI is assumed to be _{xt (m), q (s)} .

  Also, the inquiry interval is set to 5120 ms, for example, and the inquiry length is set to 2560 ms, for example.

Referring to FIG. 8, base station 1 broadcasts the first inquiry signal (IQ packet) in the inquiry length of period 1 ⁽¹⁾ . Then, the base station 1 receives the first FHS packet from the wireless device 21, detects the _first received signal strength x1 _{(1), 1 (21)} , and the first FHS packet from the wireless device 22. And the first received signal strength x _{1 (1), 1 (22)} is detected.

Thereafter, the base station 1 broadcasts the second inquiry signal (IQ packet) in the inquiry length of period 1 ⁽¹⁾ . Then, the base station 1 receives the second FHS packet from the wireless device 21, detects the second received signal strength x1 _{(1), 2 (21),} and receives the first FHS packet from the wireless device 23. Receiving, detecting the _first received signal strength x _{1 (1), 1 (23)} , receiving the second FHS packet from the wireless device 22, and receiving the second received signal strength x _{1 (1), 2 ( 22)} is detected.

Further, thereafter, the base station 1 similarly receives the received signal strengths x _{2 (1), 1 (21)} , x _{2 (1), 1} from the wireless devices 21 to 23 in the inquiry length of the period 2 ^(1). ₍₂₂₎ , x2 _{(1), 2 (21)} , x2 _{(1), 1 (23)} , x2 _{(1), 2 (22)} are detected (see (a) of FIG. 8).

Similarly to the base station 1, the base station 2 receives the received signal strengths x _{1 (2), 1 (21)} , x _{1 (2), 1 (22)} , _{1 in} the inquiry length of the period 1 ⁽² ₎ . x _{1 (2), 2 (21)} , x _{1 (2), 1 (23)} , x _{1 (2), 2 (22)} are detected, and the received signal strength x in the inquiry length of period 2 ⁽²⁾ _{2 (2), 1 (21)} , x2 _{(2), 1 (22)} , x2 _{(2), 2 (21)} , x2 _{(2), 1 (23)} , x2 _{(2), 2 (22)} is detected (see FIG. 8B).

Then, the microcomputer 121 of the base station 1 receives the received signal strengths x _{1 (1), 1 (21)} , x _{1 (1), 1 (22)} , x _{1 (1} ^{) in} the inquiry length of the period 1 ^(1). _{), 2 (21)} , x1 _{(1), 1 (23)} , x1 _{(1), 2 (22)} are stored in the storage device 122 in association with the period 1 ⁽¹⁾ . In addition, the microcomputer 121 of the base station 1 receives the received signal strengths x _{1 (2), 1 (21)} , x _{1 (2), 1 (22)} , x _{1 (2} ^{) in} the inquiry length of period 2 ^(1). _{), 2 (21)} , x1 _{(2), 1 (23)} , x1 _{(2), 2 (22)} are stored in the storage device 122 in association with the period 2 ⁽¹⁾ .

Further, the microcomputer 121 of the base station 2 receives the received signal strengths x _{1 (2), 1 (21)} , x _{1 (2), 1 (22)} , x _{1 (2} ^{) in} the inquiry length of the period 1 ^(2). _{), 2 (21)} , x1 _{(2), 1 (23)} , x1 _{(2), 2 (22)} are stored in the storage device 122 in association with the period 1 ⁽²⁾ . Further, the microcomputer 121 of the base station 2 receives the received signal strengths x _{2 (2), 1 (21)} , x _{2 (2), 1 (22)} , x _{2 (2} ^{) in} the inquiry length of period 2 ^(2). _{), 2 (21)} , x2 _{(2), 1 (23)} , x2 _{(2), 2 (22)} are stored in the storage device 122 in association with the period 2 ⁽²⁾ .

Note that the periods 1 ⁽¹⁾ , 2 ⁽¹⁾ ,... In the base station 1 are asynchronous with the periods 1 ⁽²⁾ , 2 ⁽²⁾ ,.

  FIG. 9 is a diagram for explaining a method for identifying the distances between the base stations 1 to 16 and the radio apparatuses 21 to 30.

When the microcomputer 121 of the base station 1 identifies the distance to the wireless device 21 in the period after the inquiry length of period 1 ⁽¹⁾ , 1 m: distance identification function P1 (x | μ, σ ² ) 3m: distance discrimination function P2 (x | μ, σ ² ), 6m: P3 (x | μ, σ ² ) and 1 ⁽¹⁾ : x _{1 (1), 1 (21)} , x _{1 (1), 2 (21)} is read from the storage device 122.

Base station m has detected on the basis of the FHS packet received from the wireless device s in one period ^{t (m) Q (s)} number of received signal strength _{x t (m), 1 (} s), x t (m) _{, 2 (s) 2} ,..., X _{t (m), Q (s) 1} , the average value ^(s) x _{t (m)} is expressed by the following equation.

When the microcomputer 121 of the base station 1 reads the received signal strengths x _{1 (1), 1 (21)} , x _{1 (1), 2 (21)} , the received signal strengths x _{1 (1), 1 (21)} , X _{1 (1), 2 (21)} average value ⁽²¹⁾ x _{1 (1)} is calculated by equation (4).

Then, the microcomputer 121 of the base station 1 uses the average value ⁽²¹⁾ x _{1 (1)} as a random variable of the distance identification functions P1 (x | μ, σ ² ) to P3 (x | μ, σ ² ). Then, the microcomputer 121 of the base station 1 refers to the distance identification function P1 (x | μ, σ ² ) (= GD1), and the probability value P1_ (21 corresponding to the average value ⁽²¹⁾ x _{1 (1).} ) Is calculated. More specifically, the microcomputer 121 of the base station 1 calculates the probability value P1_ (21) by substituting the average value ⁽²¹⁾ x _{1 (1)} for x in the equation (1).

Further, the microcomputer 121 of the base station 1 refers to the distance discrimination function P2 (x | μ, σ ² ) (= GD2) and uses the same method to determine the probability corresponding to the average value ⁽²¹⁾ x _{1 (1).} The value P2_ (21) is calculated.

Further, the microcomputer 121 of the base station 1 refers to the distance discrimination function P3 (x | μ, σ ² ) (= GD3) and uses the same method to determine the probability corresponding to the average value ⁽²¹⁾ x _{1 (1).} The value P3_ (21) = 0 is calculated.

  And since the probability value P1_ (21) is larger than the probability values P2_ (21) and P3_ (21), the microcomputer 121 of the base station 1 has the maximum of the probability values P1_ (21) to P3_ (21). The probability value P1_ (21) is detected.

Then, the microcomputer 121 of the base station 1 uses the distance (= 1 m) corresponding to the distance discrimination function P1 (x | μ, σ ² ) from which the maximum probability value P1_ (21) is obtained to the base station 1 and the wireless device. It is identified as the distance between 21. The microcomputer 121 of the base station 1 detects a distance of 1 m as an identification distance between the base station 1 and the wireless device 21.

Since each of the probability values P1_ (21) to P3_ (21) represents the degree of distribution of the received signal strength ⁽²¹⁾ x _{1 (1)} , the microcomputer 121 of the base station 1 performs the identification distance by the method described above. detecting a is the distance microcomputer 121 of the base station 1 is more discriminant function ^{P1 (x | μ, σ 2} ) ~P3 (x | μ, σ 2) with reference to the detected received signal strength ^{( 21) A} _first maximum distribution degree (= P1_ (21)), which is a degree of the maximum distribution among the degrees of distribution of the received signal strength corresponding to x1 ₍₁₎ , is detected, and the detected first maximum A distance (= 1 m) corresponding to the distance identification function P1 (x | μ, σ ² ) from which the distribution degree (= P1_ (21)) is obtained is detected as an identification distance between the base station 1 and the wireless device 21. It corresponds to that.

In the period after the inquiry length of period 1 ⁽¹⁾ , the microcomputer 121 of the base station 1 1 ⁽¹⁾ : received signal strength x _{1 (1), 1 (22)} , x _{1 (1), 2 ( 22)} , x _{1 (1), 1 (23)} are read out from the storage means 122, and the received received signal strengths x _{1 (1), 1 (22)} , x _{1 (1), 2 (22)} , x _{1 Based on (1) and 1 (23)} , the identification distance between the base station 1 and the wireless devices 22 and 23 is detected by the method described above.

In this case, since the received signal strength of the FHS packet received from the wireless device 23 is one received signal strength x _{1 (1), 1 (23)} , the microcomputer 121 of the base station 1 uses this one. The probability values P1_ (23) to P3_ (23) are calculated by substituting the received signal strengths x1 _{(1) and 1 (23)} for x in the equations (1) to (3).

Further, the microcomputer 121 of the base station 1 similarly detects the identification distance between the base station 1 and the radio apparatuses 21 to 23 in the period after the inquiry length of period 2 ⁽¹⁾ .

Further, the microcomputer 121 of the base station 2 is connected to the base station 2 and the wireless devices 21 through the same method as the microcomputer 121 of the base station 1 in the period after the inquiry length of the periods 1 ⁽²⁾ and 2 ^(2). The identification distance from the terminal 23 is detected.

  Further, in each of the base stations 3 and 4, the microcomputer 121 periodically detects the identification distance between the base stations 3 and 4 and the wireless devices 21 to 23 by the same method as the microcomputer 121 of the base station 1.

  Further, the microcomputer 121 of the base stations 5 to 8 periodically detects the identification distance between the base stations 5 to 8 and the wireless devices 24 to 26 by the same method as the microcomputer 121 of the base station 1.

  Further, the microcomputer 121 of the base stations 9 to 12 periodically detects the identification distance between the base stations 9 to 12 and the wireless devices 27 and 28 by the same method as the microcomputer 121 of the base station 1.

  Further, the microcomputer 121 of the base stations 13 to 16 periodically detects the identification distance between the base stations 13 to 16 and the wireless devices 29 and 30 by the same method as the microcomputer 121 of the base station 1.

  That is, the microcomputer 121 of the base stations 1 to 16 calculates the identification distance D (x, λ) by the following formula.

  As described above, in the embodiment of the present invention, the microcomputer 121 of each of the base stations 1 to 16 detects the distribution at each distance of the received signal strength RSSI of the FHS packet actually measured in a multipath environment as a Gaussian distribution. Then, referring to the distance discrimination function composed of the detected Gaussian distribution, the probability (= probability) of the distance between the base station and the wireless device corresponding to the received signal strength detected at the time of distance identification is obtained, and the maximum A distance corresponding to a distance identification function that provides a certainty (= probability) is detected as an identification distance between the base station and the radio apparatus.

  As a result, the Gaussian distribution (= distance identification) increases as the degree of deviation between the received signal strength detected at the time of identifying the identification distance and the received signal strength at which the degree of distribution of the received signal strength measured in advance is maximized. The probability with respect to the distance corresponding to the function) is reduced. On the other hand, as the degree of deviation between the received signal strength detected at the time of identifying the identification distance and the received signal strength at which the distribution of the received signal strength measured in advance is maximized, the Gaussian distribution (= distance discriminant function) The probability for the distance corresponding to) increases.

  Therefore, even if the distance between each base station 1-16 and each radio | wireless apparatus 21-30 is detected using the received signal strength RSSI detected in the multipath environment, the influence by fluctuation of the received signal strength is removed. Thus, the distance between the base station and the wireless device can be accurately detected.

  When the microcomputer 121 of each of the base stations 1 to 16 detects the identification distance between the wireless devices 21 to 30, the microcomputer 121 calculates a base station identification function for identifying the base stations 1 to 16 by the following method.

  FIG. 10 is a diagram illustrating an example of weights when obtaining a base station identification function. FIG. 11 is a conceptual diagram of a base station identification function.

Referring to FIG. 10, the weights w _i are determined so as to increase linearly from, for example, the Gaussian distribution GD3 toward the Gaussian distribution GD1. That is, the weight w _i increases linearly as the distance between the base station and the wireless device approaches 6 m, 3 m, and 1 m.

The reason why the weight w _i is determined as shown in FIG. 10 is as follows. In a multipath environment, the received signal strength RSSI decreases with multiple reflections, particularly even at short distances. In this case, the error in distance identification caused by the multipath component can be reduced by reducing the weight in the region where the received signal strength RSSI is small.

  Then, the base station identification function P (x | λ) is calculated by the following equation.

In equation (6), λ is a set of parameters (mean μ _i and variance σ _i ² ) of the received signal strength RSSI and weights w _i estimated for each different distance in advance {μ _i , σ _i ² , w _i }. i = 1 to N, where N is the number of distance discrimination functions.

When the base station identification function P (x | λ) is calculated using the weight w _i shown in FIG. 10, the result is as shown in FIG.

The microcomputer 121 of each of the base stations 1 to 16 substitutes the distance identification functions P1 (x | μ, σ ² ) to P3 (x | μ, σ ² ) read from the storage device 122 into the formula (6), At t ^(m) , the base station identification function P ( ^(s) x _{t (m)} | λ) for the wireless device s is calculated.

Thereafter, the microcomputer 121 of each of the base stations 1 to 16 determines the base station identification function P ( ^(s) x _t calculated in the period t ^(m) −1 to the period t ^(m) −H + 1 (H is a positive integer). ₍ M _{) −1} | λ) to P ( ^(s ) xt ( _{m) −H + 1} | λ) are read from the storage device 122, and the base station identification function P ( ^(s ) xt _(m) | λ) to P Substituting ( ^(s) _{xt (m) -H + 1} | λ) into the following equation, the base station identification function / P ( ^(s) _{xt (m)} | λ) is calculated.

  Note that H in Expression (7) is determined in consideration of a time interval in which the stays in the rooms R1 to R4 of the wireless devices 21 to 30 are to be confirmed. And H is set to 30000 ÷ 5120≈6, for example, when the time interval in which the stays in the rooms R1 to R4 of the wireless devices 21 to 30 are to be confirmed is 30 s.

The microcomputers 121 of the base stations 1 to 16 detect the identification distance D ( ^(s) x _{t (m)} , λ) and calculate the base station identification function / P ( ^(s) x _{t (m)} | λ). Then, the period t ( ^m ), the address Adds of the wireless device s, the received signal strength ^(s) _{xt (m)} , the identification distance D ( ^(s) _{xt (m)} , λ), and the base station identification function / P ( Packet PKT = [Addm | t ( ^m ) | Adds | ^(s) xt _(m) | D ( ₎ including data consisting of ^(s) xt _(m) | λ) m and the address Addm of the base station m ^(S) _{xt (m)} , λ) | / P ( ^(s) _{xt (m)} | λ) m] is generated. Then, the microcomputer 121 of the base stations 1 to 16 sends the packet PKT = [Addm | t ( ^m ) | Adds | ^(s) xt _(m) | D ( ^(s) xt _(m) , λ) | / P ( ^(s) _{xt (m)} | λ) m] is transmitted to the server 40 via a wired cable (not shown).

  FIG. 12 is a configuration diagram of the reception buffer. Referring to FIG. 12, reception buffer RBF is provided in storage device 42, and includes reception buffers RBF1 to RBF4. The reception buffer RBF1 is a reception buffer of the base stations 1 to 4 belonging to the room R1, the reception buffer RBF2 is a reception buffer of the base stations 5 to 8 belonging to the room R2, and the reception buffer RBF3 is a base buffer belonging to the room R3. The reception buffers of the stations 9 to 12, and the reception buffer RBF4 is a reception buffer of the base stations 13 to 16 belonging to the room R4.

  The reception buffer RBF1 stores data received from the base stations 1 to 4, the reception buffer RBF2 stores data received from the base stations 5 to 8, and the reception buffer RBF3 receives data received from the base stations 9 to 12. The reception buffer RBF4 stores data received from the base stations 13-16.

FIG. 13 is a diagram showing a data storage form in the reception buffer shown in FIG. Referring to FIG. 13, the reception buffer RBF1 receives data (= t ⁽¹⁾ | Adds | ^(s) xt ₍₁₎ | D ( ^(s) xt ₍₁₎ , λ) | / P ( ^{(s )} X _{t (1)} | λ) 1) is stored in association with the address Add1 of the base station 1, and data (= t ⁽²⁾ | Adds | ^(s) x _{t (2)} | D ( ^(s) x _{t (2)} , λ) | / P ( ^(s) x _{t (2)} | λ) 2) is stored in association with the address Add2 of the base station 2, and data (= t ⁽³⁾ | Adds | ^{(s )} _{Xt (3)} | D ( ^(s) xt ₍₃₎ , λ) | / P ( ^(s) xt ₍₃₎ | λ) 3) is stored in association with the address Add3 of the base station 3. , Data (= t ⁽⁴⁾ | Adds | ^(s) xt ₍₄₎ | D ( ^(s) _{xt (4)} , λ) | / P ( ^(s) _{xt (4)} | λ) 4) The base station 4 add In association to the scan Add4.

  The reception buffer RBF2 stores the data transmitted from the base stations 5 to 8 in the same form as the reception buffer RBF1. The reception buffer RBF3 stores data transmitted from the base stations 9 to 12 in the same form as the reception buffer RBF1. Further, the reception buffer RBF4 stores the data transmitted from the base stations 13 to 16 in the same form as the reception buffer RBF1.

The receiving unit 41 of the server 40 receives the packet PKT = [Add1 | t ⁽¹⁾ | Adds | ^(s) xt ₍₁₎ | D ( ^(s) _{xt (1)} , λ) | / P ( ^(s) _{xt (1)} | λ) 1] is received from the base station 1, and the received packet PKT = [Add1 | t ⁽¹⁾ | Adds | ^(s) xt ₍₁₎ | D ( ^(s) _{xt (1)} , λ) | / P ( ^(s) xt ₍₁₎ | λ) 1] to Add1 | t ⁽¹⁾ | Adds | ^(s) xt ₍₁₎ | D ( ^(s) _{xt ( 1)} , λ) | / P ( ^(s) _{xt (1)} | λ) 1 is detected. Then, the receiving unit 41 of the server 40 sets the address Add1 to t ⁽¹⁾ | Adds | ^(s) xt ₍₁₎ | D ( ^(s) _{xt (1)} , λ) | / P ( ^(s) x _{t (1)} | λ) 1 is associated and stored in the reception buffer RBF1 of the storage device 42.

  The receiving unit 41 of the server 40 receives data from the other base stations 2 to 16, and stores the received data in any of the reception buffers RFB1 to RBF4.

  The processing unit 43 of the server 40 reads the correspondence between the base stations 1 to 16 and the rooms R1 to R4 from the storage device 42, and base stations 1 to 4, base stations 5 to 8, base stations 9 to 12, and base station It is detected that 13 to 16 are installed in the rooms R1 to R4, respectively.

  The room identification function P (x | λ, v) that determines the probability of identifying which room each wireless device 21 to 30 is staying is determined by the following equation.

In Expression (8), v _m is a weight for each base station m, n is the number of base stations installed in each room R1 to R4.

Here, the weight v _m is set as follows. The weight v _m for the base station, which causes a large noise in room identification, is lowered. For example, the weight of a base station near the corridor where radio waves may reach through the corridor, the weight of a base station installed in the vicinity where radio noise is generated from the surroundings, and the weight of a base station where the influence of the adjacent room cannot be ignored Is set small, and the weights of other base stations are set large.

The processing unit 43 of the server 40 includes base station identification functions / P ( ^(s) _{xt (1)} | λ) 1- / P ( ^(s) _{xt (} ^{) of} the base stations 1 to 4 installed in the room R1. ₄₎ Read | λ) from the reception buffers RBF1 of the base stations 1 to 4 belonging to the room R1. Then, the processing unit 43 of the server 40 expresses the read base station identification function / P ( ^(s) _{xt (1)} | λ) 1 to / P ( ^(s) _{xt (4)} | λ) by the formula ( Substituting into 8), the room identification function P (x | λ, v) R1 is calculated.

In addition, the processing unit 43 of the server 40 includes the base station identification functions / P ( ^(s) _{xt (5)} | λ) 1- / P ( ^(s) x of the base stations 5 to 8 installed in the room R2. _{t (8)} | λ) is read from the reception buffer RBF2 of the base stations 5 to 8 belonging to the room R2. Then, the processing unit 43 of the server 40 expresses the read base station identification function / P ( ^(s) _{xt (5)} | λ) 1 to / P ( ^(s) _{xt (8)} | λ) by the formula ( Substituting into 8), the room identification function P (x | λ, v) R2 is calculated.

Further, the processing unit 43 of the server 40 has the base station identification function / P ( ^(s) _{xt (9)} | λ) 1- / P ( ^(s) x of the base stations 9 to 12 installed in the room R3. _{t (12)} | λ) is read from the reception buffer RBF3 of the base stations 9 to 12 belonging to the room R3. Then, the processing unit 43 of the server 40 expresses the read base station identification function / P ( ^(s) _{xt (9)} | λ) 1 to / P ( ^(s) _{xt (12)} | λ) by the formula ( Substituting into 8), the room identification function P (x | λ, v) R3 is calculated.

Further, the processing unit 43 of the server 40 has the base station identification function / P ( ^(s) _{xt (13)} | λ) 1- / P ( ^(s) x of the base stations 13 to 16 installed in the room R4. _{t (16)} | λ) is read out from the reception buffer RBF4 of the base stations 13 to 16 belonging to the room R4. Then, the processing unit 43 of the server 40 expresses the read base station identification function / P ( ^(s) _{xt (13)} | λ) 1 to / P ( ^(s) _{xt (16)} | λ) by the formula ( Substituting into 8), the room identification function P (x | λ, v) R4 is calculated.

Then, the processing unit 43 of the server 40 receives the data (receptions) of the wireless devices 21 to 23 existing in the data DATA ₁ to ₄ associated with the addresses Add1 to Add4 of the base stations 1 to 4 installed in the room R1. Signal strength ⁽²¹⁾ _{xt (1)} to ⁽²¹⁾ _{xt (4)} , ⁽²²⁾ _{xt (1)} to ⁽²²⁾ _{xt (4)} , ⁽²³⁾ _{xt (1)} to ⁽²³⁾ _{xt (4)} ) is detected.

Then, the processing unit 43 of the server 40 substitutes the received signal strengths ⁽²¹⁾ _{xt (1)} to ⁽²¹⁾ _{xt (4)} into the room identification function P (x | λ, v) R1 to obtain the room identification probability. P (x | λ, v) R1_ (21) is calculated.

Further, the processing unit 43 of the server 40 substitutes the received signal strengths ⁽²¹⁾ _{xt (1)} to ⁽²¹⁾ _{xt (4)} into the room identification function P (x | λ, v) R2 to obtain the room identification probability. P (x | λ, v) R2_ (21) is calculated.

Further, the processing unit 43 of the server 40 substitutes the received signal strengths ⁽²¹⁾ x _{t (1)} to ⁽²¹⁾ x _{t (4)} into the room identification function P (x | λ, v) R3, and the room identification probability. P (x | λ, v) R3_ (21) is calculated.

Further, the processing unit 43 of the server 40 substitutes the received signal strengths ⁽²¹⁾ _{xt (1)} to ⁽²¹⁾ _{xt (4)} into the room identification function P (x | λ, v) R4 to obtain the room identification probability. P (x | λ, v) R4_ (21) is calculated.

  Then, the processing unit 43 of the server 40 determines the maximum room identification probability P (x | λ, v) from the room identification probabilities P (x | λ, v) R1_ (21) to P (x | λ, v) R4_ (21). v) R1_ (21) is detected. Then, the processing unit 43 of the server 40 is obtained from the room identification function P (x | λ, v) R1 in which the maximum room identification probability P (x | λ, v) R1_ (21) indicates the stay probability in the room R1. Therefore, it is detected that the wireless device 21 exists in the room R1.

  Note that the processing unit 43 of the server 40 has a maximum room identification probability P (x | λ) from a plurality of room identification probabilities P (x | λ, v) R1_ (21) to P (x | λ, v) R4_ (21). , V) Detecting R1_ (21) means that the second maximum distribution degree that is the degree of the maximum distribution among the plurality of distribution degrees corresponding to the received signal strengths received by the server 40 from the base stations 1 to 16. Is equivalent to detecting.

A plurality of probabilities calculated by substituting one received signal strength ^(s) x _{t (m)} into a plurality of room identification functions P (x | λ, v) R1 to P (x | λ, v) R4 is 1 Received signal strengths ^(s) x _{t (m)} in a plurality of room discrimination functions P (x | λ, v) R1 to P (x | λ, v) R4 corresponding to two received signal strengths ^(s) xt _(m ⁾ _{This is because} of a plurality of distribution degrees.

The processing unit 43 of the server 40 also includes received signal strengths ⁽²²⁾ x _{t (1)} to ⁽²²⁾ x _{t (4)} and room identification functions P (x | λ, v) R1 to P (x | λ, v) Based on R4, the presence of the wireless device 22 in the room R1 is detected by the method described above.

Further, the processing unit 43 of the server 40 receives the received signal strengths ⁽²³⁾ x _{t (1)} to ⁽²³⁾ x _{t (4)} and the room identification functions P (x | λ, v) R1 to P (x | λ, v) Based on R4, the presence of the wireless device 23 in the room R1 is detected by the method described above.

  Then, the processing unit 43 of the server 40 detects that the base stations 5 to 8 are present in the room R2 and detects that the base stations 9 to 12 are present in the room R3 by the method described above. It detects that the stations 13 to 16 exist in the room R4.

When the processing unit 43 of the server 40 detects that the base stations 1 to 4 exist in the room R1, the data DATA _{1 to 4} = [Add1] associated with the base stations 1 to 4 installed in the room R1. : T ⁽¹⁾ | Adds | ^(s) xt ₍₁₎ | D ( ^(s) xt ₍₁₎ , λ) | / P ( ^(s) xt ₍₁₎ | λ) 1, Add2: t ⁽²⁾ | Adds | ^(s) x _{t (2)} | D ( ^(s) x _{t (2)} , λ) | / P ( ^(s) x _{t (2)} | λ) 2, Add3: t ^{(3 )} | Adds | ^(s) xt ₍₃₎ | D ( ^(s) xt ₍₃₎ , λ) | / P ( ^(s) xt ₍₃₎ | λ) 3, Add4: t ⁽⁴⁾ | Adds | ^(s) xt ₍₄₎ | D ( ^(s) xt ₍₄₎ , λ) | / P ( ^(s) xt ₍₄₎ | λ) 4] is read from the reception buffer RBF1.

Then, the processing unit 41 of the server 40 determines whether or not the data (received signal strength) of the wireless devices 21 to 23 exists in the read data DATA ₁ to ₄ .

When the data (received signal strength) of the wireless device 21 exists in the data DATA ₁ to ₄ , the processing unit 43 of the server 40 addsAdd1: t ⁽¹⁾ | Add21 | ⁽²¹⁾ x _{t (1)} | D ( ⁽²¹⁾ xt ₍₁₎ , λ) | / P ( ⁽²¹⁾ xt ₍₁₎ | λ) 1, Add2: t ⁽²⁾ | Add21 | ⁽²¹⁾ xt ₍₂₎ | D ( ^{(21 )} Xt ₍₂₎ , λ) | / P ( ⁽²¹⁾ xt ₍₂₎ | λ) 2, Add3: t ⁽³⁾ | Add21 | ⁽²¹⁾ xt ₍₃₎ | D ( ⁽²¹⁾ x _{t (3)} , λ) | / P ( ⁽²¹⁾ xt ₍₃₎ | λ) 3, Add4: t ⁽⁴⁾ | Add21 | ⁽²¹⁾ xt ₍₄₎ | D ( ⁽²¹⁾ xt _{( 4)} , λ) | / P ( ⁽²¹⁾ x _{t (4)} | λ) 4 is detected from the data DATA _1-4 .

Then, the processing unit 43 of the server 40 uses the received signal strength ⁽²¹⁾ x _{t (1)} detected at the base station 1 as the probability of the base station identification function / P ( ⁽²¹⁾ x _{t (1)} | λ) 1. Substituting into variable ^(s) x _{t (m)} , the base station identification probability of base station 1 / P1_ (21) is calculated.

Also, the processing unit 43 of the server 40 receives the received signal strength ⁽²¹⁾ x _{t (2)} detected at the base station 2 and the base station identification function / P ( ⁽²¹⁾ x _{t (2)} | Similarly, based on (λ) 2, the base station identification probability / P2_ (21) of the base station 2 is calculated.

Further, the processing unit 43 of the server 40 receives the received signal strength ⁽²¹⁾ x _{t (3)} detected at the base station 3 and the base station identification function / P ( ⁽²¹⁾ x _{t (3)} | Similarly, based on (λ) 3, the base station identification probability / P3_ (21) of the base station 3 is calculated.

Further, the processing unit 43 of the server 40 receives the received signal strength ⁽²¹⁾ x _{t (4)} detected at the base station 4 and the base station identification function / P ( ⁽²¹⁾ x _{t (4)} | Similarly, based on (λ) 4, the base station identification probability / P4_ (21) of the base station 4 is calculated.

  Then, the processing unit 43 of the server 40 detects the maximum base station identification probability among the base station identification probabilities / P1_ (21) to / P4_ (21). For example, when the base station identification probability P2_ (21) is the maximum, the processing unit 43 of the server 40 determines the maximum base station identification probability P2_ (21) from the base station identification probabilities / P1_ (21) to / P4_ (21). Is detected.

Then, the processing unit 43 of the server 40 determines the base station 2 that has calculated the base station identification function / P ( ⁽²¹⁾ xt ₍₂₎ | λ) 2 from which the maximum base station identification probability P2_ (21) is obtained. The wireless device 21 detects the closest base station.

Note that the processing unit 43 of the server 40 detects the maximum base station identification probability P2_ (21) from the plurality of base station identification probabilities / P1_ (21) to / P4_ (21) to be one wireless device (for example, A plurality of received signal strengths ⁽²¹⁾ x _{t (1)} to ⁽²¹⁾ x _{t (4)} when radio waves (= response signals) transmitted from the wireless device 21) are received by a plurality of base stations 1 to ₄ This corresponds to detecting the third maximum distribution degree, which is the maximum distribution degree among the corresponding plurality of distribution degrees.

A plurality of received signal strengths ⁽²¹⁾ _{xt (1)} to ⁽²¹⁾ _{xt (4)} are respectively converted into a plurality of base station identification functions / P ( ⁽²¹⁾ _{xt (1)} | λ) 1 to / P ( ^{( 21)} x _{t (4)} | λ) Each of a plurality of probabilities calculated by substituting for 4 is one received signal strength (= received signal strength ⁽²¹⁾ x _{t (1)} to ⁽²¹⁾ x _{t (4} ^). ₎ ) Corresponding to one base station identification function (= base station identification function / P ( ⁽²¹⁾ _{xt (1)} | λ) 1- / P ( ⁽²¹⁾ _{xt (4)} | λ) This is because it is the degree of distribution of one received signal intensity in any one of 4).

  The processing unit 43 of the server 40 also detects the base station with which the wireless devices 22 and 23 are closest to the other wireless devices 22 and 23 by the method described above.

Subsequently, the processing unit 43 of the server 40 reads the data DATA _5-8 associated with the base stations 5-8 installed in the room R2 from the reception buffer RBF2, and in the read data DATA _5-8 . The presence of data (received signal strength) of the wireless devices 24 to 26 is detected.

Then, the processing unit 43 of the server 40 includes Add5: t ⁽⁵⁾ | Add24 | ⁽²⁴⁾ x _{t (5)} | D ( ⁽²⁴⁾ x _{t (5)} including the data (received signal strength) of the wireless device 24. , Λ) | / P ( ⁽²⁴⁾ xt ₍₅₎ | λ) 5, Add6: t ⁽⁶⁾ | Add24 | ⁽²⁴⁾ x _{t (6)} | D ( ⁽²⁴⁾ x _{t (6)} , λ ) | / P ( ⁽²⁴⁾ x _{t (6)} | λ) 6, Add7: t ⁽⁷⁾ | Add24 | ⁽²⁴⁾ x _{t (7)} | D ( ⁽²⁴⁾ x _{t (7)} , λ) | / P ( ⁽²⁴⁾ xt ₍₇₎ | λ) 7, Add8: t ⁽⁸⁾ | Add24 | ⁽²⁴⁾ xt ₍₈₎ | D ( ⁽²⁴⁾ xt ₍₈₎ , λ) | / P ( ⁽²⁴⁾ _{xt (8)} | λ) 8 is detected from the data DATA _5-8 .

  Thereafter, the processing unit 43 of the server 40 detects the base station 5 to which the wireless device 24 is closest by the method described above.

  Similarly, the processing unit 43 of the server 40 detects the base stations 6 and 7 with which the wireless devices 25 and 26 are closest.

  Furthermore, the processing unit 43 of the server 40 is similarly based on data associated with the base stations 9 to 12 arranged in the room R3 and the base stations 13 to 16 arranged in the room R4. The base stations 9 and 12 closest to the wireless devices 27 and 28 are detected, and the base stations 14 and 15 closest to the wireless devices 29 and 30 are detected.

  That is, the processing unit 43 of the server 40 detects the base station B (x, λ) that the wireless devices 21 to 30 are closest to using the following equation.

  In Equation (9), n is the number of base stations for each room.

The processing unit 43 of the server 40 performs the above-described method so that the wireless device 21 stays in the room R1 in the period t, the base station to which the wireless device 21 is closest is the base station 1, and the wireless device 21 It detects that it exists at the position of the identification distance D ( ⁽²¹⁾ x _{t (1)} , λ) from the base station 1.

Further, the processing unit 43 of the server 40 uses the above-described method to make sure that the wireless device 22 stays in the room R1 in the period t, the base station to which the wireless device 22 is closest is the base station 2, and the wireless device 22 is detected at the position of the identification distance D ( ⁽²²⁾ x _{t (2)} , λ) from the base station 2.

Further, the processing unit 43 of the server 40 uses the above-described method to ensure that the wireless device 23 stays in the room R1 during the period t, that the base station with which the wireless device 23 is closest is the base station 4, and the wireless device. 23 is detected at the position of the identification distance D ( ⁽²³⁾ x _{t (4)} , λ) from the base station 4.

  Similarly, the processing unit 43 of the server 40 detects the stay positions of the wireless devices 24 to 30 in the period t.

  And if the processing unit 43 of the server 40 detects the stay position of the radio | wireless apparatuses 21-30 in the period t, it will output the stay position of the detected radio | wireless apparatuses 21-30 to the display unit 44 in association with the period t.

  Then, the display unit 44 of the server 40 displays the stay positions of the wireless devices 21 to 30 in association with the period t.

  The processing unit 43 of the server 40 periodically detects the stay positions of the wireless devices 21 to 30 by the method described above, and outputs the detected stay positions of the wireless devices 21 to 30 to the display unit 44 in association with each period. Then, the display unit 44 displays the stay positions of the wireless devices 21 to 30 in association with each period.

  FIG. 14 is a flowchart for explaining the operation in the base station. In FIG. 14, the operation of the base station will be described by taking the base station 1 as an example.

  Referring to FIG. 14, when a series of operations is started, microcomputer 121 of base station 1 sets period t to t = 1 (step S1).

  Then, the microcomputer 121 of the base station 1 starts executing the inquiry during the period t (step S2). Accordingly, the base station 1 broadcasts an inquiry signal (= IQ packet) and receives a response signal (= FHS packet) from the wireless device s.

  Thereafter, the microcomputer 121 of the base station 1 determines whether or not the received signal strength RSSI from the wireless device s has been received (step S3).

  When it is determined in step S3 that the received signal strength RSSI from the wireless device s has been received, the microcomputer 121 of the base station 1 associates the address of the wireless device s with the received signal strength RSSI and stores the storage device 122. (Step S4).

  When it is determined in step S3 that the received signal strength RSSI from the wireless device s has not been received, or after step S4, the microcomputer 121 of the base station 1 determines whether or not the inquiry has ended (step S4). S5). More specifically, the microcomputer 121 of the base station 1 determines whether or not the inquiry has ended by determining whether or not 2560 ms has elapsed since the start of the inquiry.

  When it is determined in step S5 that the inquiry has not ended, the series of operations returns to step S3, and the above-described steps S3 to S5 are repeatedly executed.

  On the other hand, when it is determined in step S5 that the inquiry has ended, the microcomputer 121 of the base station 1 detects the identification distance and calculates the base station identification function (step S6).

  Then, the microcomputer 121 of the base station 1 determines whether or not to end the series of operations by determining whether or not the power of the base station 1 is turned off (step S7).

  When it is determined in step S7 that the series of operations is not finished, the microcomputer 121 of the base station 1 sets t = t + 1 (step S8). Thereafter, the series of operations returns to step S2, and the above-described steps S2 to S8 are repeatedly executed.

  On the other hand, when it is determined in step S7 that the series of operations is to be finished, the series of operations is finished.

  FIG. 15 is a flowchart for explaining the detailed operation of step S6 shown in FIG. Referring to FIG. 15, the microcomputer 121 of the base station 1 sets s = 21 after determining that the inquiry is completed in step S5 shown in FIG. 14 (step S61).

  Then, the microcomputer 121 of the base station 1 determines whether or not the data (RSSI) of the wireless device s exists in the storage device 122 (step S62).

When it is determined in step S62 that the data (RSSI) of the wireless device s exists in the storage device 122, the microcomputer 121 of the base station 1 stores the received signal strength x _{t (m), q} of the wireless device s in the storage device. The average received signal strength RSSI is calculated by substituting the read received signal strength _{xt (m), q} into the equation (4) (step S63).

Then, the microcomputer 121 of the base station 1 stores the plurality of distance identification functions P1 (x | μ, σ ² ) to P3 (x | μ, σ ² ) shown in the equations (1) to (3) in the storage device 122. And the distance discrimination probability is calculated by substituting the average calculated in step S63 into the plurality of read distance discrimination functions P1 (x | μ, σ ² ) to P3 (x | μ, σ ² ). That is, the microcomputer 121 of the base station 1 calculates the distance identification probability for each distance (step S64).

  Thereafter, the microcomputer 121 of the base station 1 detects the distance corresponding to the distance identification function that provides the maximum distance identification probability among the plurality of calculated distance identification probabilities as the identification distance (step S65).

Then, the microcomputer 121 of the base station 1 calculates the base station identification function by the method described above based on the plurality of distance identification functions P1 (x | μ, σ ² ) to P3 (x | μ, σ ² ). (Step S66).

  Then, the microcomputer 121 of the base station 1 transmits the period t, the address Adds of the wireless device s, the identification distance, and the base station identification function to the server 40 (step S67).

  When it is determined in step S62 that the data (RSSI) of the wireless device s does not exist in the storage device 122, or after step S67, the microcomputer 121 of the base station 1 has an empty buffer (storage device 122). It is determined whether or not the number of wireless devices s is the maximum number S (step S68).

  In step S68, when it is determined that the buffer (storage device 122) is not empty, or when it is determined that the number of wireless devices s is not the maximum number S, or the buffer (storage device 122) is not empty, and When it is determined that the number of wireless devices s is not the maximum number S, the microcomputer 121 of the base station 1 sets s = s + 1 (step S69).

  Thereafter, the series of operations returns to step S62, and the above-described steps S62 to S69 are repeatedly executed.

  On the other hand, when it is determined in step S68 that the buffer (storage device 122) is empty, or when it is determined that the number of wireless devices s is the maximum number S, a series of operations are performed as shown in FIG. The process proceeds to S7.

  FIG. 16 is a flowchart for explaining the reception process of the server 40. Referring to FIG. 16, when a series of operations is started, receiving unit 41 of server 40 determines whether or not data is received from base station m (step S11).

  When it is determined in step S11 that data has been received from the base station m, the receiving unit 41 of the server 40 stores the received data in a buffer (step S12).

The received data includes an address Addm of the base station m, a period t ^(m) , an address Adds of the wireless device s, a received signal strength, an identification distance, and a base station identification function.

  In step S11, when it is determined that no data is received from the base station m, or after step S12, the receiving unit 41 of the server 40 determines whether the power of the server 40 is off. Thus, it is determined whether or not a series of operations has been completed (step S13).

  When it is determined in step S13 that the series of operations has not ended, the series of operations returns to step S11, and steps S11 to S13 are repeatedly executed.

  On the other hand, when it is determined in step S13 that the series of operations has ended, the series of operations ends.

  FIG. 17 is a flowchart for explaining the position detection process of the server 40. Referring to FIG. 17, when a series of operations is started, processing unit 43 of server 40 sets r = 1 (step S21). R is an index representing one of the rooms R1 to R4.

  Then, the processing unit 43 of the server 40 determines whether or not there is data of the wireless device s in the reception buffer of the base station m belonging to the room r (Step S22).

In step S22, when it is determined that there is data of the wireless device s in the reception buffer of the base station m belonging to the room r, the processing unit 43 of the server 40 transmits the data of the wireless device s (= address Addm of the base station m). , Period t ^(m) , address Adds of wireless device s, received signal strength, identification distance, and base station identification function) are read from the storage device 42.

  Then, the processing unit 43 of the server 40 calculates the base station identification probability by substituting the received signal strength into the base station identification function, and obtains the maximum base station identification probability among the calculated base station identification probabilities. The station is calculated as a base station identification result (step S23).

  Thereafter, the processing unit 43 of the server 40 calculates a room identification function by the method described above (step S24).

  Then, the processing unit 43 of the server 40 stores the base station identification result and the room identification function in the storage device 42 (step S25).

  In step S22, when it is determined that there is no data of the wireless device s in the reception buffer of the base station m belonging to the room r, or after step S25, the processing unit 43 of the server 40 has the maximum number of rooms r. It is determined whether or not the number is R (step S26).

  When it is determined in step S26 that the number of rooms r is not the maximum number R, the processing unit 43 of the server 40 sets r = r + 1 (step S27). Thereafter, the series of operations returns to step S22, and steps S22 to S27 are repeatedly executed.

  When it is determined in step S26 that the number of rooms r is the maximum number R, the processing unit 43 of the server 40 detects the position of each wireless device s (step S28).

  Thereafter, the processing unit 43 of the server 40 determines whether or not a series of operations has ended by determining whether or not the power of the server 40 is off (step S29).

  When it is determined in step S29 that the series of operations has not ended, the series of operations returns to step S21, and steps S21 to S29 are repeatedly executed.

  On the other hand, when it is determined in step S29 that the series of operations has ended, the series of operations ends.

  FIG. 18 is a flowchart for explaining the detailed operation of step S28 shown in FIG.

  Referring to FIG. 18, when it is determined in step S26 shown in FIG. 17 that the number of rooms r is the maximum number R, the processing unit 43 of the server 40 sets s = 1 (step S281), and the room It is determined whether or not there is data of the wireless device s in the discrimination function buffer (step S282).

  In step S282, when it is determined that the data of the wireless device s is in the room identification function buffer, the processing unit 43 of the server 40 reads the received signal strength and the room identification function of the wireless device s from the storage device 42.

  Then, the processing unit 43 of the server 40 calculates a room identification result based on the received signal strength of the wireless device s and the room identification function (step S283). That is, the processing unit 43 of the server 40 detects the room where the wireless device s stays.

  Thereafter, the processing unit 43 of the server 40 extracts the base station identification result of the base station m belonging to the room identified by the room identification result from the reception buffer (step S284).

  Then, the processing unit 43 of the server 40 extracts the distance identification result (= identification distance) of the base station from the base station identification result (step S285).

  Then, the processing unit 43 of the server 40 outputs the room identification result, the base station identification result, and the distance identification result (= identification distance) to the display unit 44, and the display unit 44 outputs the room identification result, the base station identification result, and the distance. The identification result (= identification distance) is displayed (step S286).

  When it is determined in step S282 that there is no data for the wireless device s in the room identification function buffer, or after step S286, the processing unit 43 of the server 40 determines whether the number of wireless devices is the maximum number S. It is determined whether or not (step S287).

  When it is determined in step S287 that the number of wireless devices is not the maximum number S, the processing unit 43 of the server 40 sets s = s + 1 (step S288).

  Thereafter, the series of operations returns to step S282, and steps S282 to S288 are repeatedly executed.

  On the other hand, when it is determined in step S287 that the number of wireless devices is the maximum number S, the series of operations proceeds to step S29 in FIG.

  Thus, according to the embodiment of the present invention, the server 40 detects the room where each of the wireless devices 21 to 30 stays, and then detects the nearest base station to which each of the wireless devices 21 to 30 is located. Thereafter, the distance between each of the radio apparatuses 21 to 30 and the nearest base station is detected (see steps S283 to S285 in FIG. 18).

  In the embodiment of the present invention, after step S23 shown in FIG. 17 is moved to step S284 shown in FIG. 18 and the room identification result is calculated, the room identified by the room identification result is obtained in step S284. The base station identification result of the base station belonging to can be calculated.

  In this case, the processing unit 43 of the server 40 stores only the room identification function buffer in step S25 shown in FIG.

  The processing unit 43 of the server 40 periodically detects the positions of the wireless devices 21 to 30 by the method described above. Then, the processing unit 43 of the server 40 stores the detected positions of the wireless devices 21 to 30 in the storage device 42 as history information of the wireless devices 21 to 30.

  The processing unit 43 of the server 40 reads out the correspondence between the addresses Add21 to Add30 of the wireless devices 21 to 30 and the names of doctors, nurses, and engineers working in the hospital from the storage device 42, and The history information is read from the storage device 42.

  And the processing unit 43 of the server 40 detects each action history of a doctor, a nurse, and a technician based on the read correspondence and history information. For example, when the wireless device 21 stays near the base station 1 in the room R1 for a certain period, the processing unit 43 of the server 40 cares for a patient in the bed BD1 near the base station 1 by a nurse wearing the wireless device 21. Detect that

  In the above description, the microcomputer 121 of the base stations 1 to 16 calculates the distance identification probability and identifies the distance between the base stations 1 to 16 and the wireless devices 21 to 30 based on the calculated distance identification probability. However, in the embodiment of the present invention, the present invention is not limited to this, and the microcomputer 121 of the base stations 1 to 16 calculates the distance reliability P (d | x), and the calculated distance reliability P (d | X) may identify the distance between the base stations 1-16 and the wireless devices 21-30.

  In this case, the microcomputer 121 of the base stations 1 to 16 calculates the distance reliability P (d | x) by the following equation.

  In Expression (10), d is a distance such as d = 1 m, 3 m, 6 m,.

When the microcomputer 121 of the base stations 1 to 16 detects the identification distance, the maximum distance identification probability P (x | μ _d , σ _d ² ) when the identification distance is obtained and all the distance identification functions are obtained. The distance reliability P (d | x) is calculated by substituting all the distance identification probabilities P (x | μ _i , σ _i ² ) calculated using the above into equation (10).

  When the distance reliability P (d | x) is used, the microcomputer 121 of the base stations 1 to 16 calculates the distance reliability P (d | x) for each distance in step S64 shown in FIG. In step S65, the identification distance is detected based on the calculated distance reliability P (d | x).

  Then, the microcomputer 121 of the base stations 1 to 16 transmits the calculated distance reliability P (d | x) to the server 40 in step S67.

  Therefore, the server 40 stores the distance reliability P (d | x) received from the base stations 1 to 16 by the reception buffers RBF1 to RBF4. Then, the server 40 displays the distance reliability P (d | x) in step S286 shown in FIG.

  In the embodiment of the present invention, the processing unit 43 of the server 40 calculates the base station reliability P (b | x) in addition to the base station identification probability, and the calculated base station reliability P (b | X) may be used to identify the base station to which each wireless device 21-30 is closest.

  In this case, the processing unit 43 of the server 40 calculates the base station reliability P (b | x) by the following equation.

  In Expression (11), b represents the base stations 1 to 16.

The processing unit 43 of the server 40 includes all base station identification probabilities P (x _m | λ) in all base stations that have received a response signal (= FHS packet) transmitted from one wireless device, and all base stations. By substituting the maximum base station identification probability P (x _b | λ) detected from the identification probability P (x _m | λ) into the equation (11), the reliability with respect to the base station with which one wireless device is closest is obtained. A certain base station reliability P (b | x) is calculated.

  Then, the processing unit 43 of the server 40 calculates the base station reliability P (b | x) for all wireless devices staying in each room (any one of the rooms R1 to R4).

  When the base station reliability P (b | x) is used, the processing unit 43 of the server 40 calculates the base station reliability P (b | x) between step S22 and step S23 shown in FIG. In step S23, the base station identification result is calculated using the base station reliability P (b | x) in addition to the base station identification probability calculated from the base station identification function.

  In this case, the processing unit 43 of the server 40 calculates the base station having the maximum base station identification probability and the maximum base station reliability as the base station identification result.

  Further, the processing unit 43 of the server 40 stores the calculated base station reliability P (b | x) in the storage device 42 in step S25.

  Further, the processing unit 43 of the server 40 displays the base station reliability P (b | x) on the display unit 44 in step S286 shown in FIG.

  Furthermore, in the embodiment of the present invention, the processing unit 43 of the server 40 calculates the base station reliability P (b | x) instead of the base station identification probability, and the calculated base station reliability P (b | X) may be used to identify the base station to which each wireless device 21-30 is closest.

  Furthermore, in the embodiment of the present invention, the processing unit 43 of the server 40 calculates the room reliability P (r | Λ) in addition to the room identification probability, and the calculated room reliability P (r | Λ). May be used to identify the room where each of the wireless devices 21 to 30 stays.

  In this case, the processing unit 43 of the server 40 calculates the room reliability P (r | Λ) by the following equation.

  In the formula (12), r represents the rooms R1 to R4.

The processing unit 43 of the server 40 is detected from all room identification probabilities P (x _k | λ, v _k ) and all room identification probabilities P (x _k | λ, v _k ) in all the rooms R1 to R4. By substituting the maximum room identification probability P (x _r | λ, v _r ) into equation (12), the room reliability P (r | Λ), which is the reliability of the room where one wireless device stays, is obtained. Calculate.

  Then, the processing unit 43 of the server 40 calculates the room reliability P (r | Λ) for all the wireless devices staying in each room (any of the rooms R1 to R4).

  When the room reliability P (r | Λ) is used, the processing unit 43 of the server 40 calculates the room reliability P (r | Λ) and calculates the calculated room reliability P in step S283 shown in FIG. The room identification result is calculated using (r | Λ) and the room identification probability calculated from the room identification function.

  In this case, the processing unit 43 of the server 40 calculates the room having the highest room identification probability and the highest room reliability as the room identification result.

  Further, the processing unit 43 of the server 40 displays the room reliability P (r | Λ) on the display unit 44 in step S286 shown in FIG.

  Furthermore, in the embodiment of the present invention, the processing unit 43 of the server 40 calculates the room reliability P (r | Λ) instead of the room identification probability, and the calculated room reliability P (r | Λ). May be used to identify the room where each of the wireless devices 21 to 30 stays.

  Furthermore, in the embodiment of the present invention, the processing unit 43 of the server 40 uses the base station reliability P (b | x) and the room reliability P (r | Λ) to perform each wireless device 21 by the following method. The position of ˜30 may be displayed.

  The processing unit 43 of the server 40 uses a figure (polygon such as a triangle, a quadrangle, and a pentagon and a circle) that increases in size as the base station reliability P (b | x) increases. (B | x) is displayed by the display unit 44 together with the positions of the wireless devices 21 to 30.

  In addition, when the base station reliability P (b | x) is equal to or greater than the threshold th1, the processing unit 43 of the server 40 selects a patient in a bed corresponding to the base station with which the wireless device attached to the nurse is closest. Determine as the subject of nursing records.

  Further, when the base station reliability P (b | x) is lower than the threshold value th1, the processing unit 43 of the server 40 has all the rooms in the rooms where the base stations closest to the radio device attached to the nurse are installed. Select a patient for nursing records from the patient.

  Further, the processing unit 43 of the server 40 is configured such that when the base station reliability P (b | x) is lower than the threshold value th1 and the room reliability P (r | Λ) is lower than the threshold value th2, The patient who is the subject of the nursing record is selected from all the patients in both the room where the base station closest to the wireless device attached to the nurse is installed and the room adjacent to the room.

  Further, when the communication system 100 is applied to museum automatic exhibition explanation, when the base station reliability P (b | x) is equal to or greater than the threshold th1, only the exhibition explanation of the target exhibit is reproduced and the base station reliability is reproduced. When the degree P (b | x) is lower than the threshold value th1, the display explanation of the target exhibit and the exhibits in the vicinity of the target exhibit is reproduced. In this case, the room reliability P (r | Λ) and the threshold value th2 may be compared, and the exhibition explanation to be reproduced may be switched according to the comparison result.

The weights w _i shown in FIG. 10 described above are generally used for applications that place emphasis on the determination of being close to the base station. In addition to detecting the position of a nurse or the like in a medical institution as described above, this application may be used to detect the position of a visitor when providing an automatic display explanation using a PDA (Personal Digital Assistant) or the like in a museum. is assumed.

FIG. 19 is a diagram illustrating another example of weights for obtaining the base station identification function. Referring to FIG. 19, the weight w _i is determined so as to increase linearly from the Gaussian distribution GD1 toward the Gaussian distribution GD3. That is, the weight w _i increases linearly as the distance between the base station and the wireless device increases from 1 m, 3 m, and 6 m.

As an application of the weights w _i are used as shown in FIG. 19, in the regulation of the operating range of the robot in the factory, when entering the breach zone there is a target (human) (the operating range of the robot), accurately the entry The case where it identifies is assumed.

FIG. 20 is a diagram illustrating still another example of weights for obtaining a base station identification function. Referring to FIG. 20, the weight w _i is determined to be small in the Gaussian distribution GD2 and linearly increase from the Gaussian distribution GD2 toward the Gaussian distribution GD1 or from the Gaussian distribution GD2 toward the Gaussian distribution GD3. Is done. That is, the weight w _i decreases when the distance between the base station and the radio apparatus is medium, and increases linearly at a short distance or far away.

The weights w _i shown in FIG. 20 are used when importance is attached to the detection that the target wireless device exists at a certain distance from the base station. More specifically, the weight w _i shown in FIG. 20 indicates the proximity state when an event and an exhibition do not want to bring visitors close to the exhibit, but want to secure visitors within a certain range. It is used when guiding guests by observing.

  In the above description, the base stations 1 to 16 broadcast the inquiry signal, receive the response signal, and the wireless devices 21 to 30 transmit the response signal. However, in the embodiment of the present invention, However, the wireless devices 21 to 30 may broadcast the inquiry signal, receive the response signal, and allow the base stations 1 to 16 to transmit the response signal.

  In this case, each of the base stations 1 to 16 operates the above-described radio apparatuses 21 to 30, and each of the radio apparatuses 21 to 30 performs the above-described operations of the base stations 1 to 16. And each radio | wireless apparatus 21-30 calculates a radio | wireless apparatus identification function instead of a base station identification function.

  Therefore, in the embodiment of the present invention, any one of the base stations 1 to 16 and the radio apparatuses 21 to 30 transmits a response signal (radio wave), and either the base station 1 to 16 or the radio apparatuses 21 to 30 is transmitted. The other receives the response signal (radio wave), detects the identification distance, and calculates the base station identification function or the wireless device identification function.

  In the above description, the communication system 100 has been described as including the base stations 1 to 16, the wireless devices 21 to 30, and the server 40, but the embodiment of the present invention is not limited to this, The communication system according to the embodiment of the present invention only needs to include base stations 1 to 16 and radio apparatuses 21 to 30.

  If the base stations 1 to 16 and the wireless devices 21 to 30 are provided, the base stations 1 to 16 and the base stations 1 to 16 and the wireless devices 21 to 30 are based on the received signal strength even in a multipath environment. This is because the distance between can be accurately determined.

  Further, in the embodiment of the present invention, the server 40 may transmit the positions of the wireless devices 21 to 30 detected by the above-described method to the information communication system installed in the hospital by wireless communication. This information communication system includes a labor management system that manages the labor of nurses, doctors, and technicians working in hospitals, or a system in which a doctor confirms where each nurse stays. The information communication system manages the labor of nurses, doctors, and engineers using the positions of the wireless devices 21 to 30 received from the server 40, or uses the positions of the wireless devices 21 to 30 received from the server 40. The position of the nurse is transmitted to a terminal device (personal computer or the like) used by the doctor.

  Furthermore, in the embodiment of the present invention, the server 40 may perform identification distance detection, base station identification function calculation, base station identification probability calculation, room identification function calculation, and room identification probability calculation. Good.

  Furthermore, in the embodiment of the present invention, the base stations 1 to 16 may transmit the identification distance, the received signal strength, and the base station identification function in each period to the server 40 by wireless communication.

  Furthermore, in the embodiment of the present invention, the radio devices 21 to 30 constitute “a plurality of first radio devices”, and the base stations 1 to 16 constitute “a plurality of second radio devices”. The server 40 constitutes a “communication device”.

  Furthermore, in the embodiment of the present invention, the base station identification function constitutes a “first identification function”, and the room identification function constitutes a “second identification function”.

Furthermore, in the embodiment of the present invention, synthesizing the Gaussian distributions GD1 to GD3 using the weights w _i by the above-described method means that the Gaussian distributions GD1 to GD3 are synthesized by weighting according to the first rule. Equivalent to.

Furthermore, in embodiments of the present invention, to synthesize a base station identification function using the weight v _m by the method described above corresponds to synthesize the base station identification function are weighted in accordance with a second rule .

  Further, in the embodiment of the present invention, the maximum distance identification probability constitutes the “first maximum distribution degree”, and the maximum room identification probability constitutes the “second maximum distribution degree”, and the maximum The base station identification probabilities form the “third maximum distribution degree”.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

  The present invention is applied to a communication system capable of accurately determining a distance between wireless devices based on received signal strength even in a multipath environment.

  1-16 base station, 21-30 wireless device, 40 server, 41 receiving unit, 42, 122 storage device, 43 processing unit, 44 display unit, 100 communication system, 110 wireless module, 111 protocol management unit, 112 transmission processing unit , 113 wireless unit, 114 reception processing unit, 120 embedded CPU, 121 microcomputer.

Claims (11)

A plurality of first wireless devices each transmitting radio waves by wireless communication in one room of an arbitrary building;
A plurality of second wireless devices each receiving radio waves transmitted from the plurality of first wireless devices in the one room;
Each of the plurality of second wireless devices is separated from the first wireless device when the distance between the first wireless device and the first wireless device is set to one distance in the one room. A distance discriminating function indicating the relationship between the received signal strength when the transmitted radio wave is received and the degree of distribution of the received signal strength is associated with a plurality of distances to the one first wireless device in advance. And when receiving a radio wave from any one of the plurality of first radio devices, the received signal strength when the radio wave is received is detected and associated with the plurality of distances. The first maximum distribution degree which is the maximum distribution degree among the distribution degrees corresponding to the detected received signal strength is detected with reference to the plurality of distance discrimination functions held, and the detected first Distance at which the maximum distribution degree of was obtained The distance corresponding to another function to perform for the first wireless device a process of detecting as identification distances of the plurality between the self first wireless device, communication system.   Each of the plurality of second wireless devices receives Q (Q is a positive integer) radio waves from any one of the first wireless devices within a predetermined time, and receives the Q radio waves The communication system according to claim 1, wherein an average of Q received signal strengths is detected as the received signal strength.   Each of the plurality of second wireless devices further includes a first identification for identifying the second wireless device based on a result of weighting and combining the plurality of distance identification functions according to a predetermined first rule. The communication system according to claim 1, wherein the communication system is calculated as a function.   Each of the plurality of second wireless devices periodically calculates an identification function for identifying the second wireless device, and H (H is an integer equal to or larger than 2) H timings calculated at consecutive timings. The communication system according to claim 3, wherein a sum of discriminant functions is calculated as the first discriminant function.   Receiving the detected received signal strength, the plurality of identification distances, and the plurality of first identification functions from the plurality of second wireless devices arranged in the one room, A process of calculating a result obtained by weighting and combining the first identification function according to a predetermined second rule as a second identification function for identifying a room in the building is arranged in a plurality of rooms. Executed for a plurality of first discrimination functions received from two radio devices, and received from the second radio devices arranged in the plurality of rooms based on the calculated second discrimination functions The second maximum distribution degree, which is the maximum distribution degree among the plurality of distribution degrees corresponding to the received signal strength, is detected, and the detected second maximum distribution degree corresponds to the second discriminant function obtained. The room to be The first wireless device is determined as a room where the first wireless device stays, and the received signal strength received from the plurality of second wireless devices arranged in the determined room, the plurality of identification distances, and the first plurality of first devices Based on the discriminant function, the maximum of a plurality of distribution degrees corresponding to a plurality of received signal strengths when the radio waves transmitted from one first radio apparatus are received by the plurality of second radio apparatuses. A second wireless device that detects the third maximum distribution degree, which is the degree of distribution of the first wireless communication device, and transmits the first identification function from which the detected third maximum distribution degree is obtained. A process of determining the position of the one first wireless apparatus based on the identification distance received from the closest second wireless apparatus as a second wireless apparatus closest to the wireless apparatus. About wireless devices Further comprising, claim 3 or the communication system according to claim 4 a communication device for executing.   The communication apparatus further executes a process of calculating a first reliability, which is a reliability of the closest second wireless apparatus, for all of the plurality of first wireless apparatuses, and calculates the calculated first The communication system according to claim 5, wherein the plurality of calculated degrees of reliability are displayed as visual information together with the positions of the plurality of first wireless devices, using a figure whose size increases as the degree of reliability increases. The plurality of second wireless devices are arranged in the one hospital room corresponding to a plurality of beds in one hospital room in the hospital,
The communication system according to claim 6, wherein the plurality of first wireless devices are attached to doctors and nurses in the hospital.   The communication device selects a patient in a bed corresponding to the closest second wireless device as a patient for nursing records when the first reliability is equal to or higher than a first threshold. Item 8. The communication system according to Item 7.   When the first reliability is lower than a first threshold, the communication device selects a patient who is a subject of nursing records from all patients in a room where the nearest second wireless device is arranged. The communication system according to claim 7.   The communication device further executes a process of calculating a second reliability, which is a reliability of a room where the plurality of first wireless devices stay, for all of the plurality of first wireless devices, When the reliability of 1 is lower than the first threshold and the second reliability is lower than the second threshold, the room where the nearest second wireless device is located and the room The communication system according to claim 7, wherein a patient who is a subject of nursing records is selected from all patients in both rooms adjacent to the room.   The communication system according to claim 7, wherein the communication device further transmits the determined positions of the plurality of first wireless devices to an information communication system installed in the hospital.

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