Wireless network system and wireless device

Abstract

To provide a radio network system and a radio device capable of determining existence of a radio device in an abnormal state such as an identity theft state.SOLUTION: A radio network system comprises a first radio device for performing centralized control and one or more second radio devices. The second radio device receives a first signal including first identification information showing a transmission source in a first reception period, receives a second signal including second identification information showing a transmission source in a second reception period, measures first reception information on reception of the first signal, measures second reception information on reception of the second signal, and transmits first measurement information including the first reception information and the first identification information and second measurement information including the second reception information and the second identification information to the first radio device. The first radio device, when the first identification information is the same as the second identification information, compares the first reception information with the second reception information to determine whether or not a radio device in an abnormal state exists.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a wireless network system and a wireless device. [Background technology]

[0002] 2. Description of the Related Art In recent years, at manufacturing sites and factories, there have been increasing opportunities to collect sensor information in a server using wireless communication, or to control actuators such as servo motors using wireless communication.

[0003] In wireless communication, the risk of attacks such as eavesdropping, interception, and unauthorized access is higher than in wired communication. If manufacturing facilities used in manufacturing sites and factories are attacked from the outside, it may cause production stoppage and / or the mixing of defective products.

[0004] For example, in wireless communication, a certain wireless terminal #X can sniff the operation of another wireless terminal #Y and pose as wireless terminal #Y. Since the spoofed wireless terminal #X is judged by an access point and / or other wireless terminals to have the same identification information as the spoofed wireless terminal #Y and to behave in the same manner as the wireless terminal #Y, it becomes much more difficult to detect unauthorized access by the spoofed wireless terminal #A.

[0005] For example, Patent Document 1 discloses a method of detecting a wireless terminal (device) that has made an unauthorized access by setting expected operations of the wireless terminal (device) in advance. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6644784 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the method of Patent Document 1, it is difficult to anticipate all the operations of the wireless terminal in advance. In addition, since a wireless terminal masquerading as a legitimate wireless terminal mimics the operations of a legitimate wireless terminal, detection by the method of Patent Document 1 is difficult.

[0008] Non-limiting embodiments of the present disclosure contribute to the provision of a wireless network system and a wireless device that can determine the presence of a wireless device in an abnormal state such as spoofing.

Means for Solving the Problems

[0009] A wireless network system according to an embodiment of the present disclosure is a wireless network system including a first wireless device that performs central control and a plurality of second wireless devices that are wirelessly connected to the first wireless device. Each of the plurality of second wireless devices includes a second receiving circuit that receives a first signal including first identification information indicating a transmitting wireless device during a first receiving period, and receives a second signal including second identification information indicating a transmitting wireless device during a second receiving period different from the first receiving period; a measuring circuit that measures first receiving information related to the reception of the first signal and measures second receiving information related to the reception of the second signal; and a second transmitting circuit that transmits first measurement information including the first receiving information and the first identification information and second measurement information including the second receiving information and the second identification information to the first wireless device. The first wireless device includes a first receiving circuit that receives the first measurement information and the second measurement information from each of the plurality of second wireless devices, and when the first identification information included in the received first measurement information and the second identification information included in the received second measurement information are the same, compares the first receiving information included in the received first measurement information and the second receiving information included in the received second measurement information, and includes a state determination circuit that determines whether there is a wireless device in an abnormal state.

[0010] A wireless device according to one embodiment of the present disclosure is a first wireless device belonging to a wireless network, the first wireless device comprising a receiving circuit that receives first measurement information and second measurement information from each of a plurality of second wireless devices connected to the first wireless device, the first measurement information including first reception information regarding reception of a first signal received in a first reception period and first identification information indicating a source wireless device included in the first signal, and the second measurement information including second reception information regarding reception of a second signal received in a second reception period different from the first reception period and second identification information indicating a source wireless device included in the second signal; and a first state determination circuit that, if the first identification information and the second identification information are identical, compares the first reception information with the second reception information and determines whether or not a wireless device in an abnormal state is present.

[0011] A wireless network system according to an embodiment of the present disclosure includes a first wireless device performing central control and a plurality of second wireless devices wirelessly connected to the first wireless device, each of the plurality of second wireless devices including a second receiving circuit that receives a first signal including first identification information indicating a source wireless device in a first reception period and a second signal including second identification information indicating a source wireless device in a second reception period different from the first reception period, and a second receiving circuit that measures first reception information regarding reception of the first signal and measures second reception information regarding reception of the second signal. a measuring circuit for measuring a received signal from the plurality of second wireless devices, a second state judgment circuit for comparing the first received information with the second received information and judging whether or not a wireless device in an abnormal state exists if the first identification information and the second identification information are identical, and a second transmitting circuit for transmitting a judgment result in the second state judgment circuit to the first wireless device, wherein the first wireless device comprises a first receiving circuit for receiving the judgment results from each of the plurality of second wireless devices, and a first state judgment circuit for judging whether or not a wireless device in an abnormal state exists based on the judgment results corresponding to each of the plurality of second wireless devices.

[0012] A wireless device according to one embodiment of the present disclosure is a first wireless device belonging to a wireless network, the first wireless device comprising: a receiving circuit that receives a judgment result indicating whether or not a wireless device in an abnormal state exists from each of a plurality of second wireless devices belonging to the wireless network, the judgment result being obtained by each of the plurality of second wireless devices receiving a first signal including first identification information indicating a transmitting wireless device in a first reception period, receiving a second signal including second identification information indicating a transmitting wireless device in a second reception period different from the first reception period, measuring first reception information regarding the reception of the first signal, measuring second reception information regarding the reception of the second signal, and, if the first identification information and the second identification information are identical, comparing the first reception information and the second reception information to judge whether or not a wireless device in an abnormal state exists; and a first state judgment circuit that judges whether or not a wireless device in an abnormal state exists based on the judgment result corresponding to each of the plurality of second wireless devices.

[0013] These comprehensive or specific aspects may be realized as a system, an apparatus, a method, an integrated circuit, a computer program, or a recording medium, or may be realized as any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium. Effect of the Invention

[0014] According to an embodiment of the present disclosure, it is possible to determine the presence of a wireless terminal in an abnormal state such as spoofing.

[0015] Further advantages and benefits of an embodiment of the present disclosure will become apparent from the specification and drawings. Such advantages and / or benefits may be provided by some of the embodiments and features described in the specification and drawings, respectively, but not necessarily all of them may be provided to obtain one or more identical features. [Brief description of the drawings]

[0016] [Figure 1]FIG. 1 is a system configuration diagram showing an example of a wireless sensor network system according to a first embodiment. [Diagram 2] FIG. 1 is a block diagram showing an example of a configuration of a controller according to a first embodiment. [Diagram 3] FIG. 1 is a block diagram showing an example of the configuration of a wireless sensor according to a first embodiment; [Figure 4] 1 is a flowchart showing an example of an operation of the wireless sensor network system according to the first embodiment. [Diagram 5] A flowchart showing an example of an operation for determining an abnormal terminal according to the first embodiment. [Figure 6A] FIG. 1 is a diagram showing an example of an arrangement of wireless sensors according to a first embodiment; [Figure 6B] FIG. 1 is a diagram showing an example of the arrangement of a spoofed wireless sensor according to the first embodiment when the wireless sensor is located outside a building R. [Figure 7A] FIG. 6B is a diagram showing an example of an inter-terminal RSSI (Received Signal Strength Indicator) matrix collected in the example of FIG. 6A. [Figure 7B] FIG. 6C is a diagram showing an example of an inter-terminal RSSI matrix collected in the example of FIG. 6B. [Figure 8] FIG. 1 is a diagram showing an example of a system configuration in which a wireless sensor according to a first embodiment is installed in the vicinity of the wireless sensor; [Figure 9A] FIG. 1 is a diagram showing an example of an arrangement of wireless sensors according to a first embodiment; [Figure 9B] FIG. 1 is a diagram showing an example of an arrangement in which a spoofed wireless sensor according to the first embodiment is present in the vicinity of a wireless sensor; [Figure 10A] FIG. 9B is a diagram showing an example of an inter-terminal RSSI matrix collected in the example of FIG. 9A; [Figure 10B] FIG. 9C is a diagram showing an example of an inter-terminal RSSI matrix collected in the example of FIG. 9B; [Figure 11] FIG. 13 is a diagram showing an example of a system configuration of a wireless sensor network system according to a second embodiment. [Figure 12] FIG. 11 is a block diagram showing an example of a configuration of a controller according to a second embodiment. [Figure 13]FIG. 11 is a block diagram showing an example of the configuration of a wireless sensor according to a second embodiment. [Figure 14A] FIG. 6B is a diagram showing an example of an inter-terminal RSSI matrix recorded in a wireless sensor in the example of FIG. 6A; [Figure 14B] FIG. 6C is a diagram showing an example of an inter-terminal RSSI matrix recorded in a wireless sensor in the example of FIG. 6B; [Figure 14C] FIG. 14C is a diagram showing an example of a determination result of a wireless sensor based on FIGS. 14A and 14B. [Figure 15A] FIG. 6B is a diagram showing an example of an inter-terminal RSSI matrix recorded in a wireless sensor in the example of FIG. 6A; [Figure 15B] FIG. 6C is a diagram showing an example of an inter-terminal RSSI matrix recorded in a wireless sensor in the example of FIG. 6B; [Figure 15C] FIG. 15C is a diagram showing an example of a determination result of a wireless sensor based on FIGS. 15A and 15B. [Figure 16] FIG. 11 is a diagram showing an example of an abnormal state determined by a wireless sensor according to the second embodiment; [Figure 17] FIG. 13 is a diagram showing an example of a determination target of a wireless sensor according to a second embodiment; [Figure 18] FIG. 11 is a diagram showing an example of a packet format of a determination result notifying packet used by a wireless sensor according to the second embodiment to notify a determination result; [Figure 19] FIG. 13 is a diagram showing an example of a field configuration of a determination result notifying section of a determination result notifying packet transmitted by a wireless sensor according to a second embodiment; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the drawings as appropriate. However, more detailed explanation than necessary may be omitted. For example, detailed explanation of already well-known matters or duplicate explanation of substantially the same configuration may be omitted. This is to avoid the following explanation becoming unnecessarily redundant and to facilitate understanding by those skilled in the art.

[0018] It should be noted that the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0019] The wireless sensor network system of the present disclosure is applied to use cases such as aggregating various sensors installed in factories and manufacturing sites, for example, inside and outside a production line or manufacturing equipment, or in the vicinity of a production line (or manufacturing equipment), via wireless devices equipped in the sensors to a server that serves as a controller.

[0020] The wireless sensor network system includes a controller and a plurality of sensors. Each sensor includes a wireless device. Hereinafter, a sensor including a wireless device may be referred to as a wireless sensor. The wireless sensor network system in the present disclosure detects a wireless sensor in an abnormal state such as spoofing.

[0021] In the present disclosure, the ability of a certain wireless sensor (wireless sensor #X) to easily receive a signal (packet) transmitted by another wireless sensor (e.g., wireless sensor #Y) is utilized to detect a wireless sensor in an abnormal state.

[0022] For example, instead of the received radio wave strength between a controller and a wireless sensor, the received radio wave strength information of a signal received by a wireless sensor (wireless sensor #A) from another wireless sensor (wireless sensor #B) is regarded as matrix data, and a wireless sensor in an abnormal state is detected from changes in the matrix of received radio wave strength.

[0023] (Embodiment 1) The first embodiment of the present disclosure will be described in detail with reference to the drawings.

[0024] <System configuration> FIG. 1 is a system configuration diagram showing an example of a wireless sensor network system 10 according to the first embodiment.

[0025] The wireless sensor network system 10 includes a controller 20 and wireless sensors 30, 31, and 32. The controller 20 and the wireless sensors 30, 31, and 32 are examples of wireless devices belonging to the wireless sensor network system 10.

[0026] The controller 20 is wirelessly connected to the wireless sensors 30, 31, and 32. The controller 20 and the wireless sensors 30, 31, and 32 are installed in a building R surrounded by a dotted line. Here, the communication area in which the controller 20 and the wireless sensors 30, 31, and 32 communicate with each other does not have to coincide with the range of the building R. For example, the communication area may be wider than the area of ​​the building R, or narrower than the area of ​​the building R.

[0027] Each wireless sensor is assigned unique identification information (e.g., an identifier (ID) or a MAC address) for identifying the wireless sensor. Among genuine wireless sensors, there are no multiple wireless sensors with the same ID. The unique ID may be assigned or may be possessed by the wireless sensor.

[0028] In this embodiment, a wireless sensor 40 is included within the communication area between the controller 20 and the wireless sensors 30, 31, and 32.

[0029] The wireless sensor 40 is a wireless sensor masquerading as the wireless sensor 30, and is an unauthorized wireless sensor having the same ID as the wireless sensor 30. Note that in the following, an example is shown in which the wireless device performing the masquerading is a "wireless sensor", but the wireless device performing the masquerading is not limited to a "wireless sensor". Furthermore, the "wireless device" may be, for example, a "wireless communication device", a "wireless terminal", a "wireless communication terminal", a "wireless device", or a "wireless communication device".

[0030] The wireless sensor 40 has the same ID as the wireless sensor 30. In order to masquerade as the wireless sensor 30, the wireless sensor 40 sets the ID of the wireless sensor 30 as the source of the packet to be transmitted, and transmits the packet with the source set to the wireless sensor 30. As a result, the wireless sensors 31 and 32 and the controller 20 that receive the packet transmitted by the wireless sensor 40 interpret (determine) that the packet transmitted by the wireless sensor 40 is a packet transmitted by the wireless sensor 30.

[0031] The wireless sensor network system 10 in the first embodiment judges (detects) whether or not there is a wireless sensor 40 masquerading as the wireless sensor 30. The judgment that there is a wireless sensor 40 masquerading as the wireless sensor 30 may correspond to the judgment that the wireless sensor 30 is in an abnormal state. In other words, for example, the wireless sensor 30 being in an abnormal state includes a case where the wireless sensor 30 itself is in an abnormal state and a case where the wireless sensor 30 is in a normal state but a wireless sensor masquerading as the wireless sensor 30 exists.

[0032] In the first embodiment, it is assumed that the IDs of the wireless sensors 30, 31, 32, and 40 are B, A, C, and β, respectively. For example, the wireless sensor 30 may be described as the wireless sensor B. That is, in the first embodiment, the wireless sensor β is a wireless sensor masquerading as the wireless sensor B.

[0033] <Controller configuration example> The controller 20 determines whether each wireless sensor is in an abnormal state based on an initial terminal-to-terminal RSSI (Received Signal Strength Indicator) collected when the wireless sensors 30, 31, and 32 are installed, and an initial terminal-to-terminal RSSI collected at a certain point in time after the installation.

[0034] Here, the inter-terminal RSSI indicates a reception strength according to the distance between two wireless sensors, measured when a wireless sensor receives a packet from another wireless sensor. The initial stage RSSI is the inter-terminal RSSI at an initial stage when the wireless sensors 30, 31, and 32 are installed. In other words, the initial stage RSSI may be a reference inter-terminal RSSI measured at a stage when no unauthorized wireless sensor exists. The abnormal state of a wireless sensor corresponds to, for example, a state in which the wireless sensor is not a legitimate wireless sensor. In the following, the terms "wireless sensor" and "terminal" may be interchangeable. The inter-terminal RSSI may include the RSSI between two wireless sensors and the RSSI between a wireless sensor and the controller 20.

[0035] FIG. 2 is a block diagram showing an example of the configuration of the controller 20 according to the first embodiment.

[0036] The controller 20 includes a wireless unit 201 , an inter-terminal RSSI collector 202 , an abnormal state determiner 203 , and a memory unit 204 .

[0037] The wireless unit 201 performs wireless communication with wireless sensors via an antenna. The wireless unit 201 has a function of, for example, an access point that manages a star-type network.

[0038] The communication method of the wireless unit 201 may be a wireless LAN (Local Area Network) or Bluetooth (registered trademark). Alternatively, the communication method of the wireless unit 201 may be WiGig using a millimeter wave band or a specific low power radio. Alternatively, the communication method of the wireless unit 201 may be LPWA (Low Power Wide Area) such as Sigfox, Lora, and NB-IoT (Narrow Band - Internet of Things).

[0039] The inter-terminal RSSI collection unit 202 instructs each wireless sensor to measure the inter-terminal RSSI. Then, the inter-terminal RSSI collection unit 202 collects the inter-terminal RSSI measured by each wireless sensor.

[0040] Although RSSI is used as an example for explanation, it is not limited to RSSI, and other information such as reception information, reception quality information, and received signal strength information related to signal reception may also be used. For example, SINR (Signal to Interference and Noise power Ratio), SNR (Signal to Noise Ratio), etc. can be mentioned.

[0041] The abnormal state determination unit 203 detects a wireless sensor in an abnormal state based on the initial-stage inter-terminal RSSI acquired at the time of installation and the inter-terminal RSSI acquired after installation.

[0042] The storage unit 204 stores the inter-terminal RSSI collected from the wireless sensors 30, 31, and 32.

[0043] <Configuration example of wireless sensor> The wireless sensor 30 receives packets transmitted by the wireless sensors 31 and 32 other than the wireless sensor 30, and measures the inter-terminal RSSI based on the received packets. The wireless sensor 30 stores the measured inter-terminal RSSI in association with the information of the transmission source, and transmits the stored inter-terminal RSSI to the controller 20. When the wireless sensor 30 receives a packet transmitted by a wireless sensor pretending to be the wireless sensor 30, it transmits a packet indicating self-terminal detection to the controller 20.

[0044] FIG. 3 is a block diagram showing an example of the configuration of the wireless sensors 30, 31, and 32 according to the first embodiment. Hereinafter, an example in which the configuration shown in FIG. 3 is the configuration of the wireless sensor 30 will be described.

[0045] The wireless sensor 30 includes a wireless unit 301, an RSSI measurement unit 302, a sensor unit 303, and a self-terminal detection unit 304.

[0046] The wireless unit 301 performs wireless communication with the controller 20 via an antenna. The wireless unit 301 has a function of a station in a star network, for example.

[0047] When a packet is received, the RSSI measurement unit 302 measures the RSSI of the received packet.

[0048] The sensor unit 303 includes, for example, a photoelectric sensor, and transmits the detected sensor value to the controller 20.

[0049] The sensor may be, for example, a fiber sensor, a displacement sensor, an image sensor, a proximity sensor, a microphoto sensor, a rotary encoder, a vibration sensor, a contact sensor, a tilt sensor, a human presence sensor, an illuminance sensor, a touch sensor, or a combination of multiple sensors. The wireless sensor network system 10 may include multiple sensors that are different from each other. For example, the wireless sensor 30, the wireless sensor 31, and the wireless sensor 32 may be different sensors from each other.

[0050] The self-terminal detection unit 304 detects whether or not the ID indicating the source of the received packet is the same as the ID of the wireless sensor 30. In the wireless sensor network system of this embodiment, half-duplex communication is used as an example of the wireless method. In half-duplex communication, the same wireless sensor does not transmit and receive simultaneously, so that, for example, the wireless sensor 30 utilizes the fact that it does not receive a packet having the ID of the wireless sensor 30 (a packet in which the ID of the wireless sensor 30 is set in the packet source). Note that full-duplex communication may be used as the wireless method. In full-duplex communication, the same wireless sensor may transmit and receive simultaneously, but, for example, the wireless sensor 30 can grasp the transmission time when the wireless sensor 30 transmitted a packet. Therefore, in full-duplex communication, it is possible to utilize the fact that the wireless sensor 30 does not receive a packet having the ID of the wireless sensor 30 at a time different from this transmission time.

[0051] Furthermore, the own terminal detection unit 304 detects whether or not packets with the same ID indicating the source have been detected a predetermined number of times (for example, twice) or more among a plurality of packets received within a predetermined time period.

[0052] The own terminal detection unit 304 transmits own terminal detection information indicating the above detection result to the controller 20.

[0053] <Operation flow of wireless sensor network system> 4 is a flowchart showing an example of the operation of the wireless sensor network system 10 according to the first embodiment. This flow is started, for example, at the stage when the wireless sensor network system 10 is installed. Alternatively, this flow may be started when a new wireless sensor is added to the wireless sensor network system, when the position of a wireless sensor is moved, and / or after regular maintenance of the system.

[0054] In step S31, the controller 20 instructs the wireless sensors 30, 31, and 32 to measure the inter-terminal RSSI in order to collect the inter-terminal RSSI in an initial state (an example of a first reception period) in which the wireless sensors 30, 31, and 32 are installed. In step S31, when the wireless sensors 30, 31, and 32 that have received the instruction to measure the inter-terminal RSSI receive a packet from another wireless sensor, they measure the inter-terminal RSSI based on the received packet and transmit the measured inter-terminal RSSI to the controller 20.

[0055] As an example, the controller 20 transmits packets instructing the measurement of inter-terminal RSSI to the wireless sensors 30, 31, and 32 in order. In response to the packet instructing the measurement of inter-terminal RSSI received from the controller 20, the wireless sensors 30, 31, and 32 transmit packets including information indicating the already measured inter-terminal RSSI to the controller 20. When the wireless sensors 30, 31, and 32 receive a packet (e.g., a packet including information indicating the inter-terminal RSSI) transmitted from another wireless sensor to the controller 20, they measure the RSSI and store the measured RSSI as the inter-terminal RSSI. The controller 20 transmits packets instructing the measurement of inter-terminal RSSI until it has collected the inter-terminal RSSI from each of the wireless sensors present in the wireless network it manages.

[0056] The controller 20 stores the inter-terminal RSSI (hereinafter, may be referred to as "first inter-terminal RSSI") collected from the wireless sensors 30, 31, and 32. Then, the process of step S32 is executed.

[0057] In step S32, the controller 20 determines whether it is time to determine whether the wireless sensor is in an abnormal state. For example, the determination timing may be set periodically. In this case, the controller 20 may determine whether it is time to determine whether the wireless sensor is in an abnormal state based on the set period.

[0058] If it is not the determination timing ("NO" in step S32), the process in step S32 is executed until the determination timing is reached. If it is the determination timing ("YES" in step S32), the process in step S33 is executed.

[0059] In step S33, the controller 20 collects terminal-to-terminal RSSI from the wireless sensors 30, 31, and 32 during operation (an example of a second reception period) in the same manner as in step S31. The controller 20 saves the terminal-to-terminal RSSI collected from the wireless sensors 30, 31, and 32 (hereinafter, may be referred to as "second terminal-to-terminal RSSI"). Note that a packet used by the wireless sensor to measure the RSSI may not include information indicating the already measured terminal-to-terminal RSSI, as shown in step S31. For example, the wireless sensor may receive a packet transmitted by another wireless sensor and including other information such as sensor data, and measure the RSSI. For example, the wireless sensors 30, 31, and 32 receive a packet (a packet including other information such as sensor data) transmitted to the controller 20 by the wireless sensor 40 disguised as the wireless sensor 30, and measure the terminal-to-terminal RSSI between the wireless sensor 40 and themselves. Then, the process of step S34 is executed.

[0060] When the wireless sensor 30 receives a signal transmitted by a wireless sensor 40 masquerading as the wireless sensor 30, the wireless sensor 30 may transmit to the controller 20 a packet including its own terminal detection information.

[0061] In step S34, the controller 20 determines whether or not there is a wireless sensor in an abnormal state based on the first inter-terminal RSSI and the second inter-terminal RSSI collected from the wireless sensors 30, 31, and 32, and the self-terminal detection information. The process of step S34 will be described later. Then, the process of step S35 is executed.

[0062] In step S34, the controller 20 judges whether or not to end the determination of the wireless sensor in the abnormal state. For example, the controller 20 may end the determination of the wireless sensor in the abnormal state when maintenance of the wireless sensor network system 10 (such as repair of the wireless sensor in the abnormal state) is performed, when the wireless sensor network system 10 is stopped or enters a sleep state, or when the terminal-to-terminal RSSI collection in the initial state (for example, S31) is repeated, etc.

[0063] If the determination of the wireless sensor in an abnormal state is not terminated (\"NO\" in S35), the process of step S32 is executed. If the determination of the wireless sensor in an abnormal state is terminated (\"YES\" in S35), the flow of FIG. 4 ends.

[0064] <Flowchart for determining an abnormal terminal> Next, with reference to FIG. 5, an example of the determination of the wireless sensor in an abnormal state shown in step S34 of FIG. 4 will be described. FIG. 5 is a flowchart showing an example of the operation for determining an abnormal terminal according to the first embodiment.

[0065] In step S41, the controller 20 compares the first inter-terminal RSSI and the second inter-terminal RSSI acquired from the wireless sensors 30, 31, and 32. Then, the controller 20 determines whether the difference in the inter-terminal RSSI is greater than a threshold value between the first inter-terminal RSSI and the second inter-terminal RSSI. For example, the difference in the inter-terminal RSSI may be an absolute value. Also, the threshold value may be a value of 0 or more.

[0066] If the difference in the inter-terminal RSSI is greater than the threshold value (\"YES\" in step S41), the controller 20 determines that there is a wireless sensor (terminal) in an abnormal state (step S43).

[0067] If the difference in the inter-terminal RSSI is not greater than the threshold value (\"NO\" in step S41), the process of step S42 is executed.

[0068] Here, exemplarily, the wireless sensor 40 masquerading as the wireless sensor 30 makes an unauthorized access to the controller 20 from a location different from the location where the wireless sensors 30, 31, and 32 are installed.

[0069] Since the wireless sensor 40 masquerades as the wireless sensor 30, for example, when the controller 20 receives a packet transmitted by the wireless sensor 40, the controller 20 may mistakenly recognize the received packet as a packet transmitted by the wireless sensor 30. Furthermore, when the controller 20 receives a packet transmitted by the wireless sensor 40, the RSSI measured by the controller 20 may vary due to fluctuations in the surrounding radio wave environment. Therefore, it is difficult to determine, based on the RSSI measured by the controller 20, whether or not there is a wireless sensor masquerading as the wireless sensor 30.

[0070] Therefore, the controller 20 extracts the wireless sensor 40 masquerading as the wireless sensor 30 from the change in the terminal-to-terminal RSSI measured by each wireless sensor.

[0071] In step S42, the controller 20 judges whether the wireless sensors 30, 31, and 32 have detected the ID of their own wireless sensor (own ID) in the received packet and / or whether they have detected the same ID multiple times in the multiple received packets. This judgment may be based on the own terminal detection information, for example. Therefore, if the ID of the own wireless sensor (own ID) is not checked, the wireless sensors 30, 31, and 32 do not need to include the own terminal detection unit 304.

[0072] For example, if there is a wireless sensor 40 masquerading as wireless sensor 30, the wireless sensor 40 will transmit a packet with the same ID as that of wireless sensor 30 set as the source ID. The wireless sensor 30 recognizes that the source ID of the received packet is the same as that of wireless sensor 30, and determines that it has received a packet with the ID of wireless sensor 30 set as the source ID, which wireless sensor 30 should not have received. When the controller 20 receives self-terminal detection information indicating this determination result, it determines that the wireless sensors 30, 31, and 32 have detected their own wireless sensor ID (own ID) in the received packet.

[0073] Also, for example, if there is a wireless sensor 40 masquerading as the wireless sensor 30, the wireless sensor 40 will transmit a packet with the same ID as the wireless sensor 30 set as the source ID. For example, if the wireless sensors 31 and 32 receive, within a predetermined time, a packet transmitted by the wireless sensor 30 and a packet transmitted by the wireless sensor 40 masquerading as the wireless sensor 30, they will determine that the source ID of these two packets is both the ID of the wireless sensor 30. If the controller 20 receives self-terminal detection information indicating this determination result, the controller 20 will determine that the wireless sensors 30, 31 and 32 have detected the same ID multiple times in the received packets.

[0074] By using the self-terminal detection information, the controller 20 can detect a wireless sensor that is in an abnormal state due to spoofing.

[0075] When a wireless sensor 40 masquerading as the wireless sensor 30 is installed in the vicinity of the wireless sensor 30, for example, there is a possibility that there is no or a very small change between the terminal-to-terminal RSSI between the wireless sensor 31 and the wireless sensor 30 measured by the wireless sensor 31 and the terminal-to-terminal RSSI between the wireless sensor 31 and the wireless sensor 40. By using the self-terminal detection information collected from the wireless sensors 30, 31, and 32, the controller 20 becomes able to detect a wireless sensor in an abnormal state due to spoofing.

[0076] For example, when the controller 20 is notified of the self-terminal detection information ("YES" in step S42), the controller 20 determines in step S43 that there is a wireless sensor in an abnormal state. For example, as in the above example, when the wireless sensor 30 notifies the self-terminal detection information, the controller 20 determines that there is a wireless sensor masquerading as the wireless sensor 30.

[0077] When the controller 20 has not received the self-terminal detection information ("NO" in step S42), it determines that the wireless sensor is in a normal state, and ends the process.

[0078] <Example of a spoofed wireless sensor located relatively far away> A method for detecting a wireless sensor 40 when a wireless sensor 40 masquerading as the wireless sensor 30 is present far away from the wireless sensor 30 will be described below with reference to FIGS. 6A, 6B, 7A, and 7B.

[0079] Fig. 6A is a diagram showing an example of an arrangement in which wireless sensors according to the present embodiment 1 are installed. Note that Fig. 6A is similar to the example shown in Fig. 1, and therefore a description thereof will be omitted. Fig. 6A shows, for example, an arrangement immediately after the wireless sensor network system 10 is installed.

[0080] Fig. 6B is a diagram showing an example of the arrangement of a spoofed wireless sensor 40 according to the first embodiment when the sensor is located outside a building R. In Fig. 6B, the same components as those in Fig. 6A and Fig. 1 are denoted by the same reference numerals, and the description thereof may be omitted.

[0081] The wireless sensor 40 is now the wireless sensor 30 and has the same ID as the wireless sensor 30. The wireless sensor 40 is located outside the building R in which the controller 20 and the wireless sensors 30, 31, and 32 are installed. The wireless sensor 40 transmits a packet to the controller 20 from outside the building R.

[0082] As a method for the wireless sensor 40 to masquerade as the wireless sensor 30, for example, the wireless sensor 40 may sniff packets transmitted by the wireless sensor 30 to learn the operation of the wireless sensor 30.

[0083] First, the controller 20 collects inter-terminal RSSI from the wireless sensors 30, 31, and 32 that are wirelessly connected. When the wireless sensors 30, 31, and 32 receive a packet from another wireless sensor, they measure the inter-terminal RSSI and store the inter-terminal RSSI in association with a source ID included in the received packet. The method in which the wireless sensor measures the inter-terminal RSSI is not particularly limited. For example, the wireless sensor may measure the inter-terminal RSSI by transmitting and receiving a dedicated packet for measuring the inter-terminal RSSI. Alternatively, the wireless sensor may measure the inter-terminal RSSI by receiving a packet for negotiating with the controller.

[0084] Next, a description will be given of the terminal-to-terminal RSSI matrix collected and stored by the controller 20 from each wireless sensor in the state of FIG. 6A.

[0085] FIG. 7A is a diagram showing an example of an inter-terminal RSSI matrix collected in the example of FIG. 6A.

[0086] In FIG. 7A, each row indicates the ID of a wireless sensor that received a packet and measured the terminal-to-terminal RSSI from the received packet, and each column indicates the ID set to the sender of the packet used to measure the terminal-to-terminal RSSI.

[0087] For example, the row with ID "A" shows the inter-terminal RSSI measured by wireless sensor 31. The inter-terminal RSSI measured by wireless sensor 31 is -40 dBm when the source is wireless sensor 30, -70 dBm when the source is wireless sensor 32, and -30 dBm when the source is controller 20. The row with ID "B" shows the inter-terminal RSSI measured by wireless sensor 30, and the row with ID "C" shows the inter-terminal RSSI measured by wireless sensor 32. The row with ID "Controller" shows the inter-terminal RSSI measured by controller 20.

[0088] Controller 20 stores the inter-terminal RSSI collected from each wireless sensor, which is called an inter-terminal RSSI matrix, and the initial inter-terminal RSSI matrix collected at the time of installation is called a first inter-terminal RSSI matrix. This inter-terminal RSSI matrix may be read as a fingerprint.

[0089] Next, a case where a wireless sensor 40 masquerading as the wireless sensor 30 makes an unauthorized access will be described.

[0090] FIG. 7B is a diagram showing an example of an inter-terminal RSSI matrix collected in the example of FIG. 6B.

[0091] When the wireless sensor 40 masquerading as the wireless sensor 30 gains unauthorized access and transmits a packet having the ID of the wireless sensor 30, the wireless sensors 30, 31 and 32 receive the packet with the ID of the wireless sensor 30 set in the transmission source.

[0092] The position where the wireless sensor 40 exists is distant from the position where the wireless sensor 30 exists. Therefore, the inter-terminal RSSI measured by the wireless sensor 31 after receiving a packet transmitted by the wireless sensor 40 is likely to change from the inter-terminal RSSI measured by the wireless sensor 31 after receiving a packet transmitted by the wireless sensor 30. Similarly to the wireless sensor 31, the inter-terminal RSSI is also likely to change in the wireless sensor 32 and the controller 20.

[0093] For the sake of explanation, FIG. 7B separately shows the inter-terminal RSSI when wireless sensor 30 (with an ID of "B") and wireless sensor 40 (with an ID of "β") transmit.

[0094] The row with ID "A" shows the inter-terminal RSSI measured by the wireless sensor 31. The inter-terminal RSSI measured by the wireless sensor 31 is -40 dBm or -90 dBm when the wireless sensor 30 is the sender, -70 dBm when the wireless sensor 32 is the sender, and -30 dBm when the controller 20 is the sender. Here, when the wireless sensor 31 receives a packet transmitted by the wireless sensor 40 masquerading as the wireless sensor 30 and measures the inter-terminal RSSI, it determines that the measured inter-terminal RSSI is the inter-terminal RSSI when the wireless sensor 30 is the sender. Therefore, when the wireless sensor 30 is the sender, two values, -40 dBm or -90 dBm, are shown.

[0095] The row with ID "B" shows the terminal-to-terminal RSSI measured by the wireless sensor 30. Here, the wireless sensor 30 receives a packet having the same ID as the wireless sensor 30 that should not have been received, and therefore stores its own terminal detection information together with the terminal-to-terminal RSSI measured at that time.

[0096] For the rows with ID "C" and the rows with ID "controller", similarly to the row with ID "A", the wireless sensors 31 and 32 receive a packet transmitted by the wireless sensor 30 and a packet transmitted by the wireless sensor 40 that has become the wireless sensor 30, and measure the terminal-to-terminal RSSI from each of the two packets. Since the source of these two packets is both set to the wireless sensor 30, these two terminal-to-terminal RSSIs are both determined to be terminal-to-terminal RSSIs with the wireless sensor 30.

[0097] The controller 20 collects end-to-end RSSI from the wireless sensors 30, 31, and 32. The end-to-end RSSI collected at a predetermined time in the initial stage is called a second end-to-end RSSI matrix.

[0098] The controller 20 detects a wireless sensor in an abnormal state due to spoofing by comparing the first and second end-to-end RSSI matrices collected from the wireless sensor.

[0099] When comparing Figures 7A and 7B, the controller 20 determines that the wireless sensor 30 is in an abnormal state because there is a large change not only in the RSSI measured by the controller 20 but also in the inter-terminal RSSI measured by other wireless sensors.

[0100] Since the inter-terminal RSSI varies depending on the installation environment, it is not possible to determine whether the change in RSSI is due to radio wave propagation fluctuations or due to differences in the positions of the wireless sensors, using the inter-terminal RSSI measured by the controller 20. By using the change in the inter-terminal RSSI matrix, it is possible to reduce the change due to radio wave propagation fluctuations, and it is possible to detect wireless sensors in an abnormal state using the inter-terminal RSSI measured by the controller 20.

[0101] When the controller 20 detects a wireless sensor in an abnormal state in the wireless sensor network system 10, the controller 20 may notify an alert or may display the alert on a monitor that displays the system status.

[0102] <Example of a case where a spoofed wireless sensor is relatively close by> A case where a wireless sensor 40 disguised as the wireless sensor 30 is in the vicinity of the wireless sensor 30 will be described below with reference to the drawings.

[0103] FIG. 8 is a diagram showing an example of a system configuration in which a wireless sensor 40 according to the first embodiment is installed in the vicinity of a wireless sensor 30. In FIG.

[0104] The difference from the example shown in FIG. 1 is that the wireless sensor 40 masquerading as the wireless sensor 30 is located outside the building R in FIG. 1, whereas in FIG. 8 it is installed near the wireless sensor 30 inside the building R.

[0105] Fig. 9A is a diagram showing a second example of the arrangement of wireless sensors according to the embodiment 1. Note that Fig. 9A is similar to the example shown in Fig. 1, and therefore a description thereof will be omitted.

[0106] FIG. 9B is a diagram showing an example of an arrangement in which spoofed wireless sensor 40 according to the first embodiment is present in the vicinity of wireless sensor 30. In FIG.

[0107] The wireless sensor 40 shown in Fig. 9B is the same as the wireless sensor 30 as the wireless sensor 40 shown in Fig. 7B, and has the same ID as the wireless sensor 30. Unlike the wireless sensor 40 shown in Fig. 7B, the wireless sensor 40 shown in Fig. 9B is located in the building R where the controller 20 and the wireless sensors 30, 31, and 32 are installed, and is located in the vicinity of the wireless sensor 30. The wireless sensor 40 transmits a packet to the controller 20 from near the wireless sensor 30.

[0108] Fig. 10A is a diagram showing an example of an inter-terminal RSSI matrix collected in the example of Fig. 9A. As described above, Fig. 9A is similar to Fig. 1 and Fig. 6A, and Fig. 10A is similar to the inter-terminal RSSI matrix shown in Fig. 7A, so description will be omitted.

[0109] FIG. 10B is a diagram showing an example of an inter-terminal RSSI matrix collected in the example of FIG. 9B.

[0110] When a wireless sensor 40 masquerading as the wireless sensor 30 is present in the vicinity of the wireless sensor 30, for example, there is a high possibility that the inter-terminal RSSI measured by the wireless sensor 31 after receiving a packet transmitted by the wireless sensor 40 will have no difference, or the difference will be small, between the inter-terminal RSSI measured by the wireless sensor 31 after receiving a packet transmitted by the wireless sensor 30. Similarly to the wireless sensor 31, there is a high possibility that the inter-terminal RSSI of the wireless sensor 32 and the controller 20 will have no difference, or the difference will be small, between the inter-terminal RSSI of the wireless sensor 30.

[0111] Even in such a case, the wireless sensor 30 receives the packet transmitted by the wireless sensor 40 and determines that the source of the received packet is the ID of the wireless sensor 30. Therefore, the wireless sensor 30 transmits a packet including its own terminal detection information to the controller 20.

[0112] Even if there is a wireless sensor 40 masquerading as the wireless sensor 30 in the vicinity of the wireless sensor 30, the controller 20 determines that the wireless sensor 30 is in an abnormal state based on the change in the terminal-to-terminal RSSI matrix as well as the self-terminal detection information received from the wireless sensor 30 (for example, step S42 in FIG. 5).

[0113] As described above, in the first embodiment, a wireless network system including the controller 20 and a plurality of wireless sensors wirelessly connected to the controller 20 is shown. For example, the wireless sensor 30 receives a first signal (e.g., a packet) including first identification information (e.g., ID) indicating a source wireless device during a first reception period (e.g., an initial state when the system is installed), and receives a second signal including second identification information indicating a source wireless device during a second reception period (e.g., during operation) different from the first reception period. The wireless sensor 30 measures first reception information (e.g., RSSI) regarding reception of the first signal, and measures second reception information regarding reception of the second signal. The wireless sensor 30 transmits, to the controller 20, first measurement information including the first reception information and the first identification information, and second measurement information including the second reception information and the second identification information. The controller 20 receives first measurement information and second measurement information from each of a plurality of wireless sensors including the wireless sensor 30, and if the first identification information and the second identification information are identical, compares the first received information with the second received information to determine whether or not a wireless device in an abnormal state exists.

[0114] With this configuration, if there is a wireless sensor #Y masquerading as a certain wireless sensor #X, the presence or absence of the masquerading wireless sensor #Y is determined by detecting fluctuations in received information (e.g., inter-terminal RSSI) between multiple wireless sensors including wireless sensor #X and wireless sensor #Y.

[0115] For example, the controller 20 receives, from each of a plurality of sensors, measurement information indicating the measurement result of the inter-terminal RSSI measured at an initial stage and measurement information indicating the measurement result of the inter-terminal RSSI measured after the initial stage. The controller 20 then compares the matrix of the inter-terminal RSSI measured at the initial stage (first inter-terminal RSSI matrix) with the matrix of the inter-terminal RSSI measured after the initial stage (second inter-terminal matrix), and determines whether or not there is a wireless sensor in an abnormal state based on the magnitude of the change in the inter-terminal RSSI. With this configuration, the measurement results of a plurality of wireless sensors can be integrated for determination, so that the presence of an abnormal wireless terminal such as spoofing can be determined.

[0116] (Embodiment 2) The second embodiment of the present disclosure will be described in detail with reference to the drawings.

[0117] In the first embodiment, an example has been shown in which the controller collects inter-terminal RSSI from each of the wireless sensors, and detects whether or not there is a wireless sensor in an abnormal state based on the matrix of the collected inter-terminal RSSI.

[0118] In the second embodiment, it is determined whether or not an abnormal state is occurring in each wireless sensor, and the determination results are collected by the controller, and wireless sensors in an abnormal state are identified.

[0119] <System configuration> FIG. 11 is a diagram showing an example of a system configuration of a wireless sensor network system 50 according to the second embodiment.

[0120] The wireless sensor network system 50 includes a controller 60 and wireless sensors 70, 71, and 72. The controller 60 and the wireless sensors 70, 71, and 72 are examples of wireless devices belonging to the wireless sensor network system 50.

[0121] The controller 60 is wirelessly connected to the wireless sensors 70, 71, and 72. The controller 60 and the wireless sensors 70, 71, and 72 are installed in a building R surrounded by a dotted line. Here, the communication areas of the controller 60 and the wireless sensors 70, 71, and 72 do not have to coincide with the building R.

[0122] In the second embodiment, the wireless sensor 40 is included within the communication area between the controller 60 and the wireless sensors 70, 71, and 72.

[0123] The wireless sensor 40 is a wireless sensor masquerading as the wireless sensor 70, and is an unauthorized wireless sensor having the same ID as the wireless sensor 70.

[0124] In the second embodiment, it is assumed that the IDs of the wireless sensors 70, 71, 72, and 40 are B, A, C, and β, respectively. For example, the wireless sensor 70 may be described as the wireless sensor B. That is, in the second embodiment, the wireless sensor β is a wireless sensor masquerading as the wireless sensor B.

[0125] <Controller configuration example> FIG. 12 is a block diagram showing an example of the configuration of the controller 60 according to the second embodiment.

[0126] The controller 60 includes a wireless unit 601, an abnormal state determination unit (first state determination unit) 602, and a storage unit 603.

[0127] Since the wireless unit 601 has the same configuration as the wireless unit 201 shown in FIG. 2, a description thereof will be omitted.

[0128] The abnormal state determination section 602 determines whether or not there is a wireless sensor in an abnormal state, based on the results of determination by each wireless sensor.

[0129] The storage unit 603 records the results of the determinations made by each wireless sensor.

[0130] <Example of wireless sensor configuration> Fig. 13 is a block diagram showing an example of the configuration of wireless sensors 70, 71, and 72 according to the present embodiment 2. In the following, an example in which the configuration shown in Fig. 13 is the configuration of wireless sensor 70 will be described.

[0131] The wireless sensor 70 includes a wireless section 701 , an RSSI measurement section 702 , a sensor section 703 , a self-terminal detection section 704 , a determination target selection section 705 , an abnormal terminal determination section (second state determination section) 706 , and an RSSI storage section 707 .

[0132] The wireless unit 701, RSSI measurement unit 702, sensor unit 703, and own terminal detection unit 704 have the same configuration as the wireless unit 301, RSSI measurement unit 302, sensor unit 303, and own terminal detection unit 304 shown in Figure 3, respectively, so their explanations are omitted.

[0133] The determination target selection unit 705 selects a wireless sensor to be determined by the wireless sensor 70. For example, the determination target selection unit 705 selects one from the wireless sensors 71 and 72 included in the wireless sensor network system 50 and wirelessly connected to the controller 60.

[0134] The abnormal terminal determination unit 706 determines whether or not the wireless sensor selected by the determination target selection unit 705 is in an abnormal state, based on the measured first and second inter-terminal RSSI.

[0135] RSSI storage unit 707 stores the inter-terminal RSSI measured by RSSI measurement unit 702. Note that, in the first embodiment, an example has been shown in which controller 20 stores the inter-terminal RSSI of each wireless sensor, but in the second embodiment, wireless sensor 70 stores the inter-terminal RSSI measured by wireless sensor 70. Like wireless sensor 70, wireless sensor 71 stores the inter-terminal RSSI measured by wireless sensor 71, wireless sensor 72 stores the inter-terminal RSSI measured by wireless sensor 72, and controller 60 stores the inter-terminal RSSI measured by controller 60.

[0136] <Example of inter-device RSSI> The inter-terminal RSSI measured by the wireless sensors 70, 71, and 72 in the second embodiment is assumed to be the same as the inter-terminal RSSI measured by the wireless sensors 30, 31, and 32 in the first embodiment. However, in the second embodiment, the inter-terminal RSSI is not aggregated in the controller. Each wireless sensor records the measured inter-terminal RSSI, and is not aware of the inter-terminal RSSI measured by the other wireless sensors.

[0137] The inter-terminal RSSI in the second embodiment will be described below. Fig. 14A is a diagram showing an example of an inter-terminal RSSI matrix recorded in wireless sensor 71 in Fig. 6A. Fig. 14B is a diagram showing an example of an inter-terminal RSSI matrix recorded in wireless sensor 71 in Fig. 6B. Fig. 14C is a diagram showing an example of a determination result of the wireless sensor based on Fig. 14A and Fig. 14B.

[0138] The terminal-to-terminal RSSI matrix shown in Fig. 14A is the same as the row with the ID "A" shown in Fig. 7A. The terminal-to-terminal RSSI matrix shown in Fig. 14B is the same as the row with the ID "A" shown in Fig. 7B when the ID of the wireless sensor 70 is β.

[0139] The wireless sensor 71 compares the first terminal-to-terminal RSSI matrix shown in Fig. 14A with the second terminal-to-terminal RSSI matrix shown in Fig. 14Bn, and determines that the wireless sensor 70 in which a change has occurred is a candidate for a wireless sensor in an abnormal state. The wireless sensor 71 transmits information indicating the determination result to the controller 60.

[0140] The packet containing information indicating the judgment result transmitted by the wireless sensor 71 may include information on candidate wireless sensors that have been judged to be in an abnormal state and information on wireless sensors that have not been judged to be in an abnormal state.

[0141] For example, as shown in FIG. 14C, based on the judgment result, the wireless sensor 71 sets a value indicating a candidate wireless sensor in an abnormal state to “1”, sets a value indicating a wireless sensor that is not judged to be in an abnormal state to “0”, creates a bitmap containing the respective values, and transmits the bitmap indicating the judgment result to the controller 60.

[0142] Although not shown in the figure, the wireless sensor 72 and the controller 60 also compare the terminal-to-terminal RSSI matrices in the same manner as the wireless sensor 71, and determine that the wireless sensor 70 that has experienced a change is a candidate for a wireless sensor in an abnormal state.

[0143] Fig. 15A is a diagram showing an example of an inter-terminal RSSI matrix recorded in wireless sensor 70 in Fig. 6A. Fig. 15B is a diagram showing an example of an inter-terminal RSSI matrix recorded in wireless sensor 70 in Fig. 6B. Fig. 15C is a diagram showing an example of a determination result of wireless sensor 70 based on Fig. 15A and Fig. 15B.

[0144] 15B, the wireless sensor 70 receives a packet whose source ID is set to the same as the ID of the wireless sensor 70, which the wireless sensor 70 should not receive. This packet is sent by the wireless sensor 40 masquerading as the wireless sensor 70. Therefore, the wireless sensor 70 transmits its own terminal detection information (for example, information including the cells highlighted in FIG. 15C) to the controller 60.

[0145] The controller 60 aggregates the determination results of each wireless sensor.

[0146] Fig. 16 is a diagram showing an example of the determination results aggregated by the controller 60 in the present embodiment 2. In the case of Fig. 16, the determination results received from each of the wireless sensors 70, 71, and 72 indicate that the wireless sensor 70 is a candidate for a wireless sensor in an abnormal state, so the controller 60 determines that the wireless sensor 70 is a wireless sensor in an abnormal state.

[0147] The controller 60 may combine the self-terminal detection information determined by the wireless sensor as a method for determining whether or not the wireless sensor is in an abnormal state.

[0148] In the above example, the controller 60 performs a determination on the candidates for an abnormal wireless sensor in the determination results received from each of the wireless sensors 70, 71, and 72, and identifies the wireless sensor in the abnormal state. In the determination results of each wireless sensor, the candidates for an abnormal wireless sensor are not necessarily the same. In that case, the controller 60 can determine the wireless sensor in the abnormal state by using the self-terminal detection information.

[0149] As a method of determination, the controller 60 may determine that at least one of the wireless sensors 70, 71, and 72 is in an abnormal state as a wireless sensor in an abnormal state based on the determination results received from the wireless sensors 70, 71, and 72. However, since the wireless sensor determines whether it is in an abnormal state based on the terminal-to-terminal RSSI, the determination result may differ for each wireless sensor due to fluctuations in radio wave propagation.

[0150] Therefore, the controller 60 may determine that a wireless sensor is in an abnormal state when it is determined that two or more of the wireless sensors 70, 71, and 72 are in an abnormal state. The controller 60 may also determine that a wireless sensor is in an abnormal state when it is determined that a majority of the wireless sensors 70, 71, and 72 are in an abnormal state.

[0151] Furthermore, each wireless sensor notifies information indicating whether or not it is a candidate for an abnormal wireless sensor using the binary value of "1" or "0", but the notified information may be weighted.

[0152] For example, each wireless sensor may be weighted according to the time variation of the inter-terminal RSSI. For example, in the second embodiment, a case will be taken as an example in which the magnitude of the time variation of the inter-terminal RSSI between the wireless sensors 71 and 70 is smaller than the magnitude of the time variation of the inter-terminal RSSI between the wireless sensors 72 and 70. In this example, in the process in which the controller 60 determines whether the wireless sensor 70 is in an abnormal state, the determination result based on the inter-terminal RSSI of the wireless sensor 71 is more reliable than the determination result based on the inter-terminal RSSI of the wireless sensor 72. Therefore, the greater the time variation of the inter-terminal RSSI, the smaller the weighting may be.

[0153] For example, if the fluctuation in the inter-terminal RSSI measured by each wireless sensor exceeds a threshold (if the fluctuation is large), the threshold may be set to "0.5". Also, instead of assigning a weight to each wireless sensor, the weighting coefficient may be stored in the controller 60. For example, the weighting coefficient may be determined in advance by the wireless sensor, and the determined weighting coefficient may be notified to the controller 60. By notifying the controller 60 of the weighting coefficient in advance, the amount of information notified by each wireless sensor can be reduced. This is because, particularly in a wireless sensor network system, the information transmitted by the wireless sensor is the sensor information of the sensor installed therein, and therefore it is desirable to transmit less information.

[0154] The above has described a case in which each wireless sensor determines whether or not there is a wireless sensor other than the wireless sensor itself that is in an abnormal state.

[0155] When the number of wireless sensors included in the wireless sensor network system and connected to the controller increases, the amount of information indicating the judgment result transmitted from each wireless sensor to the controller increases. Therefore, it is possible to determine in advance the target to be judged by each wireless sensor and reduce the number of wireless sensors to be judged.

[0156] For example, by using the inter-terminal RSSI measured by the wireless sensor, only wireless sensors with good communication quality are subject to judgment.

[0157] An example will be described with reference to Fig. 7A. In Fig. 7A, -60 dBm is set as the threshold, and only wireless sensors with RSSIs of -60 dBm or more are subject to judgment among the wireless sensors that have measured RSSIs. In this case, the subject to be judged by the wireless sensors is shown in Fig. 17.

[0158] FIG. 17 is a diagram showing an example of a determination target of the wireless sensor according to the second embodiment.

[0159] 17, the wireless sensor 71 determines that the wireless sensor 70 is to be judged because the terminal-to-terminal RSSI of the packet transmitted by the wireless sensor 70 is -40 dBm. On the other hand, the wireless sensor 71 determines that the wireless sensor 72 is not to be judged because the terminal-to-terminal RSSI of the packet transmitted by the wireless sensor 72 is -70 dBm, which is smaller than the set threshold.

[0160] In this way, the wireless sensor 71 judges whether the wireless sensor 70, which is the subject of the judgment, is in an abnormal state, but does not judge whether the wireless sensor 72, which is not the subject of the judgment, is in an abnormal state. Therefore, the size (e.g., bit length) of the field for notifying the judgment result of the wireless sensor 71 (judgment result notification section P82 described later) can be 2 bits, including a field for notifying the own terminal detection information.

[0161] Similarly, wireless sensor 70 notifies in 3 bits including a field notifying its own terminal detection information in addition to wireless sensors 71 and 72. Wireless sensor 72 notifies in 2 bits including a field notifying its own terminal detection information in addition to wireless sensor 70.

[0162] FIG. 18 is a diagram showing an example of a packet format of a determination result notifying packet P80 used by the wireless sensor according to the second embodiment to notify the result of determination.

[0163] The determination result notifying packet P80 has a header portion P81, a determination result notifying portion P82, and a data portion P83.

[0164] The header portion P81 includes any or all of the following: identification information indicating the judgment result notification packet (e.g., frame type), identification information indicating the source wireless device (e.g., wireless sensor or controller) (e.g., MAC address, device ID), and identification information indicating the destination wireless device (e.g., wireless sensor or controller) (e.g., MAC address, device ID).

[0165] The determination result notifying section P82 contains information about the wireless sensor that has been determined to be in an abnormal state by the wireless sensor that transmitted the determination result notifying packet P80.

[0166] The data portion P83 includes information acquired by a sensor portion of the wireless sensor that transmits the determination result notifying packet P80. It is noted that the determination result notifying packet P80 does not necessarily have to include the data portion P83.

[0167] Although not shown, an error determination section and an error correction section may be added to the determination result notifying packet P80.

[0168] FIG. 19 is a diagram showing an example of a field configuration of the determination result notification section P82 of the determination result notification packet P80 transmitted by the wireless sensor 70 according to the second embodiment.

[0169] The judgment result notification section P82 has a judgment result field P821, a judgment result field P822, and a self-terminal detection field P823.

[0170] As shown in the second row of FIG. 17, the wireless sensor 70 transmits its own terminal detection information to the controller, as well as the wireless sensors 71 and 72.

[0171] The judgment result field P821 indicates the judgment result of the wireless sensor 71. For example, if the wireless sensor 70 judges that the wireless sensor 71 is an abnormal terminal, it sets “1” to the judgment result field P821, and if the wireless sensor 70 does not judge that the wireless sensor 71 is an abnormal terminal, it sets “0” to the judgment result field P821.

[0172] Like the determination result field P821, the determination result field P822 indicates the determination result of the wireless sensor 72.

[0173] The own terminal detection field P823 indicates that the wireless sensor 70 has received a packet having the ID of the wireless sensor 70. For example, when the wireless sensor 70 receives a packet having the ID of the wireless sensor 70, the own terminal detection field P823 is set to "1," and when the wireless sensor 70 does not receive a packet having the ID of the wireless sensor 70, the own terminal detection field P823 is set to "0."

[0174] As described above, in the second embodiment, a wireless network system including a controller 60 and a plurality of wireless sensors (e.g., wireless sensors 70, 71, 72) wirelessly connected to the controller 60 is shown. For example, the wireless sensor 70 receives a first signal (e.g., a packet) including first identification information (e.g., ID) indicating a wireless device that is a transmission source during a first reception period (e.g., when the system is installed), and receives a second signal including second identification information indicating a wireless device that is a transmission source during a second reception period (e.g., during operation) different from the first reception period. The wireless sensor 70 measures first reception information (e.g., RSSI) regarding reception of the first signal, and measures second reception information regarding reception of the second signal. If the first identification information and the second identification information are the same, the wireless sensor 70 compares the first reception information with the second reception information, determines whether or not a wireless device in an abnormal state exists, and transmits the determination result to the controller 60. The controller 60 receives the determination results from each of the multiple wireless sensors including the wireless sensor 70, and determines whether or not a wireless device in an abnormal state exists based on the determination results.

[0175] With this configuration, if there is a wireless sensor #Y masquerading as a certain wireless sensor #X, the presence or absence of the masquerading wireless sensor #Y is determined by detecting fluctuations in terminal-to-terminal RSSI between multiple wireless sensors including wireless sensor #X and wireless sensor #Y.

[0176] For example, the controller 60 receives comparison results from each of the plurality of wireless sensors. The received comparison results are, for example, results obtained by each of the wireless sensors comparing the measured RSSI between terminals at an initial stage with the measured RSSI between terminals measured after the initial stage. The controller 60 determines whether there is a wireless sensor in an abnormal state based on the comparison results. With this configuration, it is possible to determine the presence of a wireless terminal in an abnormal state such as spoofing.

[0177] Also, in the second embodiment, an example is shown in which each of the wireless sensors makes a primary determination based on the measured RSSI between terminals and transmits the determination result to the controller. With this configuration, it is possible to reduce the overhead of the information transmitted by the wireless sensors.

[0178] In the first and second embodiments, the timing of measuring the first RSSI between terminals is described by taking the initial stage at the time of installation of the wireless sensor as an example, but it is not necessarily limited to the initial stage at the time of installation. For example, it may be measured when a new wireless sensor is added to the wireless sensor network system or during regular maintenance.

[0179] Also, as the wireless method, a wireless communication method using a single channel is described as an example, but a wireless communication method using frequency hopping may also be used. In this case, it may be determined whether it is in an abnormal state based on the RSSI between terminals measured on a plurality of frequency channels that hop.

[0180] In addition, in each of the above embodiments, a star type has been described as an example of a wireless network topology, but a mesh type network or a ring type network may also be used. In each of the above embodiments, an example in which the wireless sensor network system has one controller and three wireless sensors has been described, but the present disclosure is not limited to this. For example, the wireless sensor network system may have two or more controllers, or may have two or less, or four or more wireless sensors. Alternatively, the wireless sensor network system may include a wireless device other than the controller and the wireless sensors.

[0181] Further, in each of the above embodiments, an example has been described in which a wireless sensor receives packets from each of other wireless sensors and a controller and measures inter-terminal RSSI, but the present disclosure is not limited to this. Since a wireless sensor does not receive packets from other wireless sensors and some of the controllers, it may not need to measure inter-terminal RSSI. For example, wireless sensor #X does not receive packets from other wireless sensor #Y or a controller that exists outside the communication area of ​​wireless sensor #X, and may not need to measure inter-terminal RSSI. In this case, some elements of the inter-terminal RSSI matrix may be "empty".

[0182] Although the above-described embodiments have been described with reference to a wireless sensor network system, the present disclosure is not limited thereto, and may be applied to a wireless network other than a wireless sensor network.

[0183] Although spoofing has been described as an example of an abnormal state of a wireless sensor, the present disclosure is not limited thereto. For example, the abnormal state of a wireless sensor may be unauthorized access by a wireless sensor having an ID that has not been registered in advance in the controller, or may be an abnormal state caused by a malfunction of the wireless sensor (a decrease in the transmission power of the wireless device, a decrease in the receiving capability). In each of the above-mentioned embodiments, it is also possible to detect these abnormal states in the same way as the example of spoofing.

[0184] In the above embodiment, the difference between the terminal-to-terminal RSSI matrices is used to determine whether the wireless sensor is in an abnormal state, but the terminal-to-terminal RSSI matrix (for example, the above-mentioned first terminal-to-terminal RSSI matrix) may be acquired initially (for example, at the time of installation) multiple times and the acquired terminal-to-terminal RSSI matrix may be learned as teacher data. The controller may determine whether a terminal is abnormal from the teacher data acquired and learned initially and the acquired terminal-to-terminal RSSI.

[0185] In the above-described embodiments, the notation "... part" used for each component may be replaced with other notations such as "... circuitry", "... assembly", "... device", "... unit", or "... module".

[0186] Although the embodiments have been described above with reference to the drawings, the present disclosure is not limited to such examples. It is clear that a person skilled in the art can come up with various modified or altered examples within the scope of the claims. It is understood that such modified or altered examples also belong to the technical scope of the present disclosure. In addition, the components in the embodiments may be arbitrarily combined within the scope of the present disclosure.

[0187] The present disclosure can be realized by software, hardware, or software in cooperation with hardware. Each functional block used in the description of the above embodiment may be realized partially or entirely as an LSI, which is an integrated circuit, and each process described in the above embodiment may be controlled partially or entirely by one LSI or a combination of LSIs. The LSI may be composed of individual chips, or may be composed of one chip so as to include some or all of the functional blocks. The LSI may have input and output of data. Depending on the degree of integration, the LSI may be called an IC, a system LSI, a super LSI, or an ultra LSI.

[0188] The method of integration is not limited to LSI, and may be realized by a dedicated circuit, a general-purpose processor, or a dedicated processor. Also, after LSI manufacturing, a programmable FPGA (Field Programmable Gate Array) or a reconfigurable processor that can reconfigure the connections and settings of circuit cells inside the LSI may be used. The present disclosure may be realized as digital processing or analog processing.

[0189] Furthermore, if a new integrated circuit technology that can replace LSI appears due to the progress of semiconductor technology or a derivative technology, it is possible to integrate the functional blocks using that technology. The application of biotechnology is also a possibility.

[0190] The present disclosure may be implemented in any type of apparatus, device, or system having a communication function (collectively referred to as a communication apparatus). The communication apparatus may include a radio transceiver and processing / control circuitry. The radio transceiver may include a receiver and a transmitter, or both as functions. The radio transceiver (transmitter and receiver) may include a radio frequency (RF) module and one or more antennas. The RF module may include an amplifier, an RF modulator / demodulator, or the like. Non-limiting examples of communication devices include telephones (e.g., cell phones, smartphones, etc.), tablets, personal computers (PCs) (e.g., laptops, desktops, notebooks, etc.), cameras (e.g., digital still / video cameras), digital players (e.g., digital audio / video players), wearable devices (e.g., wearable cameras, smart watches, tracking devices, etc.), game consoles, digital book readers, telehealth and telemedicine devices, communication-enabled vehicles or mobile conveyances (e.g., cars, airplanes, boats, etc.), and combinations of the above devices.

[0191] Communications Equipment includes, but is not limited to portable or mobile equipment, non-portable or fixed equipment, devices and systems of any kind, such as smart home devices (appliances, lighting equipment, smart meters or metering devices, control panels, etc.), vending machines and any other "Things" that may exist on an Internet of Things (IoT) network.

[0192] Communications include data communications via cellular systems, wireless LAN systems, communications satellite systems, etc., as well as data communications via combinations of these.

[0193] A communications apparatus also includes devices, such as controllers and sensors, connected or coupled to a communications device that performs the communications functions described in this disclosure, such as controllers and sensors that generate control and data signals used by the communications device to perform the communications functions of the communications apparatus.

[0194] The communication apparatus also includes infrastructure facilities, such as base stations, access points, and any other apparatus, device, or system that communicates with or controls the various apparatuses listed above, but are not limited to these.

[0195] Summary of the Disclosure A wireless network system according to an embodiment of the present disclosure includes a first wireless device performing central control and a plurality of second wireless devices wirelessly connected to the first wireless device, each of the plurality of second wireless devices including a second receiving circuit that receives a first signal including first identification information indicating a source wireless device in a first receiving period and receives a second signal including second identification information indicating a source wireless device in a second receiving period different from the first receiving period, a measurement circuit that measures first receiving information regarding the reception of the first signal and measures second receiving information regarding the reception of the second signal, and a first receiving circuit that measures the first receiving information and the first identification information. and a second transmitting circuit that transmits to the first wireless device the measurement information and second measurement information including the second received information and the second identification information, wherein the first wireless device comprises a first receiving circuit that receives the first measurement information and the second measurement information from each of the plurality of second wireless devices, and a state determination circuit that, when the first identification information included in the received first measurement information and the second identification information included in the received second measurement information are identical, compares the first received information included in the received first measurement information with the second received information included in the received second measurement information to determine whether or not a wireless device in an abnormal state exists.

[0196] In a wireless network system according to one embodiment of the present disclosure, the state determination circuit determines that a wireless device in an abnormal state is present when a difference between the first reception information included in the received first measurement information and the second reception information included in the received second measurement information is equal to or greater than a threshold value.

[0197] In a wireless network system according to one embodiment of the present disclosure, the second wireless device further includes a detection circuit that detects whether either the first identification information or the second identification information includes identification information of the second wireless device, the second transmission circuit transmits the detection result of the detection circuit to the first wireless device, and the first receiving circuit of the first wireless device receives the detection result, and the state judgment circuit judges that the source of the second signal is a wireless device in an abnormal state if the detection result indicates that the detection result includes identification information indicating the second wireless device.

[0198] A wireless device according to one embodiment of the present disclosure is a first wireless device belonging to a wireless network, the first wireless device comprising a receiving circuit that receives first measurement information and second measurement information from each of a plurality of second wireless devices connected to the first wireless device, the first measurement information including first reception information regarding reception of a first signal received in a first reception period and first identification information indicating a source wireless device included in the first signal, and the second measurement information including second reception information regarding reception of a second signal received in a second reception period different from the first reception period and second identification information indicating a source wireless device included in the second signal; and a first state determination circuit that, if the first identification information and the second identification information are identical, compares the first reception information with the second reception information and determines whether or not a wireless device in an abnormal state is present.

[0199] A wireless network system according to an embodiment of the present disclosure is a wireless network system including a first wireless device that performs central control and a plurality of second wireless devices wirelessly connected to the first wireless device. Each of the plurality of second wireless devices receives a first signal including first identification information indicating a source wireless device during a first reception period, and receives a second signal including second identification information indicating a source wireless device during a second reception period different from the first reception period. A second reception circuit, a measurement circuit that measures first reception information regarding reception of the first signal and measures second reception information regarding reception of the second signal, and when the first identification information and the second identification information are the same, compares the first reception information and the second reception information, and a second state determination circuit that determines whether there is a wireless device in an abnormal state, and a second transmission circuit that transmits the determination result in the second state determination circuit to the first wireless device. The first wireless device includes a first reception circuit that receives the determination result from each of the plurality of second wireless devices, and a first state determination circuit that determines whether there is a wireless device in an abnormal state based on the determination result corresponding to each of the plurality of second wireless devices.

[0200] In the wireless network system according to an embodiment of the present disclosure, when the difference between the first reception information included in the received first measurement information and the second reception information included in the received second measurement information is equal to or greater than a threshold value, the second state determination circuit determines that there is a wireless device in the abnormal state.

[0201] In the wireless network system according to an embodiment of the present disclosure, the second wireless device further includes a detection circuit that detects whether any of the first identification information and the second identification information includes identification information of the second wireless device. When the detection result in the detection circuit indicates that it includes identification information indicating the second wireless device, the second state determination circuit determines that the source of the second signal is the wireless device in the abnormal state.

[0202] A wireless device according to one embodiment of the present disclosure is a first wireless device belonging to a wireless network, the first wireless device comprising: a receiving circuit that receives a judgment result indicating whether or not a wireless device in an abnormal state exists from each of a plurality of second wireless devices belonging to the wireless network, the judgment result being obtained by each of the plurality of second wireless devices receiving a first signal including first identification information indicating a transmitting wireless device in a first reception period, receiving a second signal including second identification information indicating a transmitting wireless device in a second reception period different from the first reception period, measuring first reception information regarding the reception of the first signal, measuring second reception information regarding the reception of the second signal, and, if the first identification information and the second identification information are identical, comparing the first reception information and the second reception information to judge whether or not a wireless device in an abnormal state exists; and a first state judgment circuit that judges whether or not a wireless device in an abnormal state exists based on the judgment result corresponding to each of the plurality of second wireless devices. [Industrial Applicability]

[0203] The present disclosure is useful for wireless sensor network systems. [Explanation of symbols]

[0204] 10 Wireless Sensor Network System 20, 60 Controller 30, 31, 32, 40, 70, 71, 72 Wireless sensors 201, 301, 601, 701 Radio section 202 Inter-terminal RSSI collection unit 203, 602 Abnormal condition judgment unit 204, 603 Storage section 302, 702 RSSI measurement section 303, 703 Sensor part 304, 704 Self-terminal detection unit 705 Judgment Subject Selection Department 706 Abnormal Terminal Judgment Unit 707 RSSI storage

Claims

1. A wireless network system including a first wireless device that performs central control and a plurality of second wireless devices that are wirelessly connected to the first wireless device, Each of the plurality of second wireless devices a second receiving circuit that receives a first signal including first identification information indicating a source wireless device in an initial state in which the second wireless device is installed, and receives a second signal including second identification information indicating a source wireless device during operation after the initial state; a measurement circuit for measuring first reception information relating to reception of the first signal and for measuring second reception information relating to reception of the second signal; a second transmission circuit configured to transmit, to the first wireless device, first measurement information including the first reception information and the first identification information, and second measurement information including the second reception information and the second identification information; Equipped with The first wireless device is a first receiving circuit for receiving the first measurement information and the second measurement information from each of the plurality of second wireless devices; a state determination circuit for, when the first identification information included in the received first measurement information and the second identification information included in the received second measurement information are identical, comparing the first reception information included in the received first measurement information with the second reception information included in the received second measurement information and determining whether or not there is a wireless device in an abnormal state; A wireless network system comprising:

2. the state determination circuit determines that a wireless device in the abnormal state is present when a difference between the first reception information included in the received first measurement information and the second reception information included in the received second measurement information is equal to or greater than a threshold value; 2. The wireless network system according to claim 1.

3. The second wireless device is a detection circuit for detecting whether either the first identification information or the second identification information includes an identification information of the second wireless device; the second transmission circuit transmits a detection result of the detection circuit to the first wireless device; the first wireless device, the first receiving circuit receiving the detection result; the state determination circuit determines that the source of the second signal is a wireless device in an abnormal state when the detection result indicates that the detection result includes identification information indicating the second wireless device.

2. The wireless network system according to claim 1.

4. A first wireless device belonging to a wireless network, The first wireless device is a receiving circuit that receives first measurement information and second measurement information from each of a plurality of second radio devices connected to the first radio device, the first measurement information including first reception information regarding reception of a first signal received in an initial state in which the second radio device is installed and first identification information included in the first signal and indicating a source radio device, and the second measurement information including second reception information regarding reception of a second signal received during operation after the initial state and second identification information included in the second signal and indicating a source radio device; a first state determination circuit for, if the first identification information and the second identification information are identical, comparing the first reception information with the second reception information and determining whether or not there is a wireless device in an abnormal state; A wireless device comprising:

5. A wireless network system including a first wireless device that performs central control and a plurality of second wireless devices that are wirelessly connected to the first wireless device, Each of the plurality of second wireless devices a second receiving circuit that receives a first signal including first identification information indicating a source wireless device in an initial state in which the second wireless device is installed, and receives a second signal including second identification information indicating a source wireless device during operation after the initial state; a measurement circuit for measuring first reception information relating to reception of the first signal and for measuring second reception information relating to reception of the second signal; a second state determination circuit that, when the first identification information and the second identification information are identical, compares the first reception information with the second reception information and determines whether or not there is a wireless device in an abnormal state; a second transmission circuit that transmits a result of the determination in the second state determination circuit to the first wireless device; Equipped with The first wireless device is a first receiving circuit for receiving the determination results from each of the plurality of second wireless devices; a first state determination circuit that compares the determination results corresponding to the plurality of second radio devices, and determines that the third radio device is an abnormal radio device when a predetermined number or more of the determination results indicate that the third radio device is in an abnormal state; A wireless network system comprising:

6. the second state determination circuit determines that a wireless device in the abnormal state is present when a difference between the first reception information included in the received first measurement information and the second reception information included in the received second measurement information is equal to or greater than a threshold value; 6. The wireless network system according to claim 5.

7. The second wireless device is a detection circuit for detecting whether either the first identification information or the second identification information includes an identification information of the second wireless device; the second state determination circuit determines that a source of the second signal is the wireless device in the abnormal state when a detection result in the detection circuit indicates that the second signal includes identification information indicating the second wireless device; 6. The wireless network system according to claim 5.

8. A first wireless device belonging to a wireless network, The first wireless device is a receiving circuit that receives a determination result indicating whether or not a wireless device in an abnormal state exists from each of a plurality of second wireless devices belonging to the wireless network, the determination result being obtained by each of the plurality of second wireless devices receiving a first signal including first identification information indicating a wireless device that is a transmission source in an initial state in which the second wireless device is installed, receiving a second signal including second identification information indicating a wireless device that is a transmission source during operation after the initial state, measuring first reception information regarding the reception of the first signal, measuring second reception information regarding the reception of the second signal, and, if the first identification information and the second identification information are identical, comparing the first reception information with the second reception information to determine whether or not a wireless device in an abnormal state exists; a first state determination circuit that compares the determination results corresponding to the plurality of second radio devices, and determines that the third radio device is an abnormal radio device when a predetermined number or more of the determination results indicate that the third radio device is in an abnormal state; A wireless device comprising:

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