Packet monitoring device, program, and packet monitoring method

Abstract

To provide a device, a program, and a method of more surely determining a factor of a failure generated.SOLUTION: In a wireless data sensing system, a packet monitoring device 1 monitors a sensor information packet transmitted to an edge terminal 4 from wireless communication terminals 3-1 to 3-7, determines that an abnormality occurs in the wireless communication terminals 3-1 to 3-7 in the case where the sensor information packet is not detected for certain wireless communication terminals 3-1 to 3-7 even if a reference period defined in accordance with a measurement period of a sensor connected to the wireless communication terminals 3-1 to 3-7 passes, and determines that a delay occurs in a transmission path even if a packet achievement time that is a difference between a measurement date of a sensor value contained in the sensor information stored in the sensor information packet and a detection data of the sensor information packet in the packet monitoring device 1 exceeds a threshold time determined on the basis of a past packet achievement time even in the case where the sensor information packet is detected in the reference period.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to packet monitoring technology for a wireless data sensing system using IoT (Internet of Things).

Background Art

[0002] In recent years, wireless data sensing systems that use IoT to manage the operating status of various facilities such as factories have become widespread. A wireless data sensing system includes sensors installed in various facilities such as factories, a wireless communication terminal connected to the sensors that wirelessly transmits sensor information of the connected sensors, an edge terminal that collects sensor information of each sensor and manages the operating status of various facilities, and a gateway that receives sensor information wirelessly transmitted from the wireless communication terminal and transmits it to the edge terminal. In such a wireless data sensing system, it is desirable to quickly detect a communication failure and identify its cause.

[0003] For example, Patent Document 1 discloses a cause identification device that can identify whether the cause of a missing sensor information collected by a wireless sensor network (equivalent to a wireless data sensing system) is in a node (equivalent to a wireless communication terminal) or in a propagation path. When a missing sensor information occurs in any node, this cause identification device compares the reception levels of received power between nodes close to the node where the sensor information is missing (referred to as adjacent nodes) before and after the occurrence of the missing sensor information. If there is no change in the reception levels of received power between adjacent nodes, it is considered that correct reception is possible between adjacent nodes even after the occurrence of the missing information. In this case, the cause identification device determines that the abnormality of the node itself where the sensor information is missing is the cause of the missing sensor information. On the other hand, if there is a change in the reception levels of received power between adjacent nodes, it is considered that correct reception is not possible between adjacent nodes even after the occurrence of the missing information. In this case, the cause identification device determines that the propagation path abnormality of the wireless network is the cause of the missing sensor information.

Prior Art Documents

Patent Documents

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-211317 [Summary of the Invention] [Problems to be Solved by the Invention]

[0005] However, the technique described in Patent Document 1 is to determine the cause when sensor information is missing at any node, and does not address failures where sensor information is not missing. Further, for example, when sensor information is missing at any node due to an abnormality of the node itself, and at the same timing, if sensor information is also missing at any of the neighboring nodes of this node, the reception level of the received power between the neighboring nodes changes before and after the occurrence of the missing sensor information. For this reason, it is misjudged that the cause of the missing sensor information is a propagation path abnormality rather than an abnormality of the node itself.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a technique for more accurately determining the cause of a failure that has occurred in a wireless data sensing system. [Means for Solving the Problems]

[0007] To solve the above problems, the present invention provides a packet monitoring device that monitors sensor information packets in a wireless data sensing system having a plurality of wireless communication terminals that are connected to sensors and wirelessly transmit sensor information packets storing sensor values of the sensors and their measurement dates and times, and an edge terminal that collects and manages the sensor information of each sensor. This packet monitoring device monitors, for each wireless communication terminal, the sensor information packet transmitted from the wireless communication terminal to the edge terminal, and if no sensor information packet from this wireless communication terminal is detected even after a reference period determined according to the measurement period of the sensor connected to this wireless communication terminal has elapsed, it determines that an abnormality has occurred in this wireless communication terminal. Further, even when a sensor information packet from the wireless communication terminal is detected within the reference period, if the difference (packet arrival time) between the measurement date and time of the sensor value included in the sensor information stored in this sensor information packet and the detection date and time of this sensor information packet by the packet monitoring device exceeds a threshold time determined based on past packet arrival times, it determines that a delay has occurred in the propagation path.

[0008] For example, the present invention A plurality of wireless communication terminals that are connected to sensors and wirelessly transmit sensor information packets storing sensor values of the sensors and their measurement dates and times, and an edge terminal that collects and manages the sensor information of each of the sensors A gateway that receives the sensor information packets wirelessly transmitted from the plurality of wireless communication terminals and transmits them to the edge terminal. In a wireless data sensing system having the same, a packet monitoring device that monitors the sensor information packet, wherein For each wireless communication terminal, a first packet monitoring means for monitoring whether or not the sensor information packet transmitted from the wireless communication terminal to the edge terminal is detected within a reference period determined according to the measurement period of the sensor connected to the wireless communication terminal For each wireless communication terminal, a second packet monitoring means for monitoring whether or not the packet arrival time, which is the difference between the measurement date and time included in the sensor information stored in the sensor information packet transmitted from the wireless communication terminal to the edge terminal and the detection date and time by the first packet monitoring means, is within a threshold time determined based on past packet arrival times For the wireless communication terminal in which the sensor information packet has not been detected within the reference period by the first packet monitoring means, it is determined that an abnormality has occurred in the wireless communication terminal. For the wireless communication terminal in which the sensor information packet has been detected within the reference period by the first packet monitoring means, when it is determined by the second packet monitoring means that the packet arrival time exceeds the threshold time, a cause determination means for determining that a delay has occurred in the propagation path is provided. 、 The plurality of wireless communication terminals are wirelessly connected in a tree structure with the gateway at the top level. The wireless communication terminal The sensor information packet including the sensor information of the sensor connected to the own wireless communication terminal, and the sensor information packet received from another wireless communication terminal located downstream of the own wireless communication terminal in the tree structure are transmitted to another wireless communication terminal located upstream of the own wireless communication terminal in the tree structure if there is such an upstream wireless communication terminal, and if not, are transmitted to the gateway. The cause determination means For the wireless communication terminal in which the sensor information packet has not been detected within the reference period by the first packet monitoring means, if it is determined that there is another wireless communication terminal located upstream of the wireless communication terminal in the tree structure and an abnormality has occurred in the other wireless communication terminal within a predetermined time, the wireless communication terminal is determined to be normal. 。

Advantages of the Invention

[0009] In the present invention, for each wireless communication terminal, the sensor information packet from the wireless communication terminal is monitored. If the sensor information packet from this wireless communication terminal is not detected even after passing a reference period determined according to the measurement period of the sensor connected to the wireless communication terminal, it is determined that a communication failure has occurred due to a terminal abnormality of this wireless communication terminal. Further, even when a sensor information packet from a wireless communication terminal is detected within the reference period, if the difference (packet arrival time) between the measurement date and time of the sensor value included in the sensor information stored in this sensor information packet and the detection date and time of this sensor information packet by the packet monitoring device exceeds a threshold time determined based on the past packet arrival time, it is determined that a communication failure due to propagation path delay has occurred in this wireless communication terminal. Therefore, when a communication failure occurs in which the sensor information packet is missing, not only can the terminal abnormality of the wireless communication terminal be specified as the cause, but even when the sensor information packet is not missing, the occurrence of the communication failure can be detected and its cause (propagation path delay) can be specified. Thus, according to the present invention, the cause of the failure occurring in the wireless data sensing system can be determined more accurately.

Brief Description of the Drawings

[0010]

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Best Mode for Carrying Out the Invention

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0012] FIG. 1 is a schematic configuration diagram of a wireless data sensing system according to this embodiment.

[0013] As shown in the figure, the wireless data sensing system according to this embodiment is for managing the operating status of various facilities such as factories using IoT, and includes a plurality of sensors 2-1 to 2-7 (hereinafter also simply referred to as sensor 2), a plurality of wireless communication terminals 3-1 to 3-7 (hereinafter also simply referred to as wireless communication terminal 3), an edge terminal 4, a gateway 5, a hub 6, and a packet monitoring device 1.

[0014] The sensor 2 is installed in various facilities such as factories, measures sensor values related to the operating status of the target facility, and outputs the sensor values and their measurement dates and times.

[0015] The wireless communication terminal 3 is connected to the sensor 2, and each time the sensor 2 measures a sensor value, it wirelessly transmits a sensor information packet storing the sensor value and its measurement date and time.

[0016] Here, the wireless communication terminals 3-1 to 3-7 are wirelessly connected in a tree structure with the gateway 5 at the top. Each wireless communication terminal 3 transmits a sensor information packet including the sensor information of the sensor 2 connected to the own wireless communication terminal 3, and a network connection information packet including the network connection information indicating the connection relationship of the own wireless communication terminal 3. If there is another wireless communication terminal 3 (hereinafter referred to as the parent terminal) located upstream of the own wireless communication terminal 3 in the tree structure, it is transmitted to this parent terminal. If not, it is transmitted to the gateway 5. In addition, when there is another wireless communication terminal 3 (hereinafter referred to as the child terminal) located downstream of the own wireless communication terminal 3 in the tree structure, each wireless communication terminal 3 relays the packet exchange between this child terminal and the parent terminal (or the gateway 5 if there is no parent terminal).

[0017] In the example shown in FIG. 1, there is no parent terminal for the wireless communication terminals 3-1 and 3-2, and each is wirelessly connected to the gateway 5. The child terminal of the wireless communication terminal 3-1 is the wireless communication terminal 3-3, and the child terminal of the wireless communication terminal 3-3 is the wireless communication terminal 3-5. There is no child terminal for the wireless communication terminal 3-5. Also, the child terminal of the wireless communication terminal 3-2 is the wireless communication terminal 3-4, and the child terminals of the wireless communication terminal 3-4 are the wireless communication terminals 3-6 and 3-7. There is no child terminal for the wireless communication terminals 3-6 and 3-7.

[0018] The edge terminal 4 is an IoT server that collects and manages the sensor information of each sensor 2 and displays (visualizes) the operating status of various facilities such as factories in a graph or the like.

[0019] The gateway 5 receives the sensor information packet wirelessly transmitted from each wireless communication terminal 3 and transmits it to the edge terminal 4.

[0020] The hub 6 network-connects between the packet monitoring device 1, the edge terminal 4, and the gateway 5. In addition, the hub 6 has a mirroring function and mirrors the packets transmitted and received between the edge terminal 4 and the gateway 5 to the packet monitoring device 1.

[0021] Then, for each wireless communication terminal 3, the packet monitoring device 1 monitors the sensor information packets mirrored by the hub 6, and detects communication failures caused by terminal abnormalities, propagation path delays, and propagation path abnormalities.

[0022] FIG. 2 is a sequence diagram for explaining packet monitoring preparation processing in the wireless data sensing system according to the present embodiment.

[0023] Here, the packet monitoring preparation processing is a process for collecting information such as the connection relationship of each wireless communication terminal 3 and the measurement period of the sensor connected to each wireless communication terminal 3 (hereinafter referred to as the sensor measurement period) in order for the packet monitoring device 1 to monitor the sensor information packets wirelessly transmitted from each wireless communication terminal 3. For example, it is performed when the wireless data sensing system is started up.

[0024] First, the edge terminal 4 transmits a terminal setting information packet storing terminal setting information including the sensor measurement period set for each wireless communication terminal 3 to each wireless communication terminal 3 (S100). This terminal setting information packet is wirelessly transmitted from the gateway 5 to each wireless communication terminal 3 via the hub 6, and each wireless communication terminal 3 sets the sensor measurement period and the like for its own wireless communication terminal 3 according to the terminal setting information of its own wireless communication terminal 3 included in the terminal setting information packet. At this time, the hub 6 mirrors the terminal setting information packet transmitted from the edge terminal 4 to each wireless communication terminal 3 to the packet monitoring device 1 (S101).

[0025] When the packet monitoring device 1 detects the terminal setting information packet transmitted from the edge terminal 4 to each wireless communication terminal 3, it transmits a terminal list information request to the edge terminal 4 (S102). This terminal list information request is transmitted to the edge terminal 4 via the hub 6. In response to this, the edge terminal 4 transmits terminal list information including the sensor measurement period of each wireless communication terminal 3 managed by this edge terminal 4 to the packet monitoring device 1 (S103). This terminal list information is transmitted to the packet monitoring device 1 via the hub 6.

[0026] Next, based on the terminal list information received from the edge terminal 4, the packet monitoring device 1 creates a terminal monitoring table that stores the sensor measurement period, connection relationship, and reference period and threshold time used for packet monitoring for each wireless communication terminal 3 (S104). Here, the reference period is set to be longer than the period obtained by adding a predetermined retry period (packet retransmission time) to the sensor measurement period. At this point, the connection relationship and threshold time of each wireless communication terminal 3 are unknown, and the fields in the terminal monitoring table that store these for each wireless communication terminal 3 are left blank (NuLL data).

[0027] After that, when each wireless communication terminal 3 completes various settings such as the sensor measurement period based on the terminal setting information packet received from the edge terminal 4, it wirelessly transmits a network connection information packet storing network connection information including the connection relationship (information on the parent terminal and child terminals) of its own wireless communication terminal 3 to the edge terminal 4 (S105). This network connection information packet is received by the gateway 5 and transmitted to the edge terminal 4 via the hub 6. At this time, the hub 6 mirrors the network connection information packet wirelessly transmitted from the wireless communication terminal 3 to the edge terminal 4 to the packet monitoring device 1 (S106).

[0028] When the packet monitoring device 1 detects a network connection information packet wirelessly transmitted from the wireless communication terminal 3 to the edge terminal 4, it registers the connection relationship of the wireless communication terminal 3 that is the source of the network connection information packet in the terminal monitoring table based on the network connection information stored in this network connection information packet, and updates the terminal monitoring table (S107). This process is performed for all network connection information packets wirelessly transmitted from all wireless communication terminals 3.

[0029] After that, each wireless communication terminal 3 wirelessly transmits a sensor information packet storing the latest sensor value output by the sensor 2 connected to the own wireless communication terminal 3 and the measurement date and time thereof, in accordance with the sensor measurement period set for the own wireless communication terminal 3, to the edge terminal 4 (S108). Here, when the sensor measurement period is not set for the own wireless communication terminal 3, for example, when a predetermined event such as the sensor 2 connected to the own wireless communication terminal 3 detecting an abnormality occurs, a sensor information packet storing the sensor value output by the sensor 2 and the measurement date and time thereof is wirelessly transmitted to the edge terminal 4. Then, the hub 6 mirrors the sensor information packet transmitted from the wireless communication terminal 3 toward the edge terminal 4 to the packet monitoring device 1 (S109).

[0030] Next, each time the packet monitoring device 1 detects a sensor information packet transmitted from a wireless communication terminal 3 toward the edge terminal 4 for each wireless communication terminal 3, it accumulates the detection date and time together with the packet arrival time specified by subtracting the measurement date and time included in the sensor information stored in this sensor information packet from this detection date and time (S110).

[0031] After that, for each wireless communication terminal 3, if the packet arrival times are accumulated by a predetermined number or more, the packet monitoring device 1 determines the above-described threshold time used for packet monitoring based on the average value of the predetermined number or more of packet arrival times accumulated until then. Then, it registers the packet arrival times of each wireless communication terminal 3 in the terminal monitoring table and updates the terminal monitoring table (S111).

[0032] FIG. 3 is a sequence diagram for explaining a first operation example of packet monitoring processing in the wireless data sensing system according to the present embodiment.

[0033] As described above, the wireless communication terminal 3 wirelessly transmits a sensor information packet including the sensor information of the sensor 2 connected to the own wireless communication terminal 3 to the edge terminal 4 (S120). At this time, the hub 6 mirrors the sensor information packet transmitted from the wireless communication terminal 3 toward the edge terminal 4 to the packet monitoring device 1 (S121). When the packet monitoring device 1 detects the sensor information packet transmitted from the wireless communication terminal 3 toward the edge terminal 4, the packet monitoring device 1 accumulates the detection date and time of the sensor information packet in association with the wireless communication terminal 3 together with the packet arrival time specified by subtracting the measurement date and time included in the sensor information stored in the sensor information packet from this detection date and time (S122).

[0034] Here, it is assumed that a terminal abnormality has occurred in any one of the wireless communication terminals 3 and the transmission of the sensor information packet by this wireless communication terminal 3 has become impossible (S123).

[0035] The packet monitoring device 1 monitors sensor information packets wirelessly transmitted from the wireless communication terminal 3 to the edge terminal 4 for each wireless communication terminal 3. When a wireless communication terminal 3 that has not detected a new sensor information packet even after the elapse of the reference period registered in the terminal monitoring table since the last detection of the sensor information packet is detected (S124), it is determined that a communication failure has occurred in this wireless communication terminal 3. Then, the packet monitoring device 1 refers to the communication failure information of the detected wireless communication terminal 3 and checks whether the detection date and time of the communication failure included in the latest communication failure information of this wireless communication terminal 3 is within a predetermined time. If it is within the predetermined time, it is checked whether the cause of the communication failure included in this latest communication failure information is "propagation path delay". Here, it is assumed that the detection date and time of the communication failure included in the latest communication failure information of this wireless communication terminal 3 is not within the predetermined time, or even if it is within the predetermined time, the cause of the communication failure included in this latest communication failure information is not "propagation path delay" (S125). In this case, the packet monitoring device 1 refers to the terminal monitoring table and checks whether there is a parent terminal for this wireless communication terminal 3. Here, it is assumed that the detected wireless communication terminal 3 is either wireless communication terminal 3-1 or 3-2 and there is no parent terminal (S126).

[0036] When the packet monitoring device 1 confirms that there is no parent terminal for the detected wireless communication terminal 3, it is determined that the cause of the communication failure that occurred in this wireless communication terminal 3 is a terminal abnormality of this wireless communication terminal 3 itself (S127). Then, the packet monitoring device 1 accumulates communication failure information including the information of the wireless communication terminal 3 in which the communication failure occurred, the cause of the communication failure "terminal abnormality", and the detection date and time of the communication failure, and outputs the communication failure information to present it to the user (S128).

[0037] FIG. 4 is a sequence diagram for explaining a second operation example of packet monitoring processing in the wireless data sensing system according to the present embodiment.

[0038] As described above, the wireless communication terminal 3 wirelessly transmits a sensor information packet including the sensor information of the sensor 2 connected to the own wireless communication terminal 3 to the edge terminal 4 (S130). At this time, the hub 6 mirrors the sensor information packet wirelessly transmitted from the wireless communication terminal 3 toward the edge terminal 4 to the packet monitoring device 1 (S131). When the packet monitoring device 1 detects the sensor information packet wirelessly transmitted from the wireless communication terminal 3 toward the edge terminal 4, the packet monitoring device 1 accumulates the detection date and time of the sensor information packet in association with this wireless communication terminal 3 together with the packet arrival time specified by subtracting the measurement date and time of the sensor value included in the sensor information stored in the sensor information packet from this detection date and time (S132).

[0039] Here, it is assumed that a terminal abnormality has occurred in the parent terminal of the wireless communication terminal 3, and as a result, the sensor information packet wirelessly transmitted from the wireless communication terminal 3 does not reach the gateway 5 (S133).

[0040] The packet monitoring device 1 monitors sensor information packets wirelessly transmitted from the wireless communication terminal 3 to the edge terminal 4 for each wireless communication terminal 3. When it detects a wireless communication terminal 3 that has not detected a new sensor information packet even after the expiration of the reference period registered in the terminal monitoring table since the last detection of the sensor information packet (S134), it determines that a communication failure has occurred in this wireless communication terminal 3. Then, the packet monitoring device 1 refers to the communication failure information of the detected wireless communication terminal 3 and checks whether the detection date and time of the communication failure included in the latest communication failure information of this wireless communication terminal 3 are within a predetermined time. If it is within the predetermined time, it checks whether the cause of the communication failure included in this latest communication failure information is "propagation path delay". Here, it is assumed that the detection date and time of the communication failure included in the latest communication failure information of this wireless communication terminal 3 are not within the predetermined time, or even if they are within the predetermined time, the cause of the communication failure included in this latest communication failure information is not "propagation path delay" (S135). In this case, the packet monitoring device 1 further checks with reference to the terminal monitoring table whether there is a parent terminal for this wireless communication terminal 3. Here, the detected wireless communication terminal 3 is any one of wireless communication terminals 3-3 to 3-7, and there is a parent terminal (S136).

[0041] Next, when the packet monitoring device 1 confirms that there is a parent terminal for the detected wireless communication terminal 3, it waits for a predetermined waiting time to elapse, and then checks whether the detection date and time of the communication failure included in the latest communication failure information of the parent terminal are within a predetermined time. If it is within the predetermined time, it checks whether the cause of the communication failure included in this latest communication failure information is "terminal abnormality". Here, it is assumed that the detection date and time of the communication failure included in the latest communication failure information of the parent terminal are within the predetermined time, and the cause of the communication failure included in this latest communication failure information is "terminal abnormality" (S137). In this case, since the communication failure of the wireless communication terminal 3 detected in S134 is likely due to the "terminal abnormality" of the parent terminal, it is determined that there is no abnormality in this wireless communication terminal 3 itself (S138).

[0042] Note that in S137, if the detection date and time of the communication failure included in the latest communication failure information of the parent terminal is not within a predetermined time, or if the detection date and time of the communication failure included in the latest communication failure information of the parent terminal is within a predetermined time but the cause of the communication failure included in this latest communication failure information is not "terminal abnormality", then in S138, it is determined that the cause of the communication failure that occurred in the wireless communication terminal 3 is a terminal abnormality of this wireless communication terminal 3 itself. While accumulating the communication failure information of this wireless communication terminal 3, the communication failure information is output and presented to the user.

[0043] FIG. 5 and FIG. 6 are sequence diagrams for explaining a third operation example of packet monitoring processing in the wireless data sensing system according to the present embodiment.

[0044] As described above, the wireless communication terminal 3 wirelessly transmits a sensor information packet including the sensor information of the sensor 2 connected to the own wireless communication terminal 3 to the edge terminal 4 (S140). At this time, the hub 6 mirrors the sensor information packet transmitted from the wireless communication terminal 3 toward the edge terminal 4 to the packet monitoring device 1 (S141). When the packet monitoring device 1 detects a sensor information packet wirelessly transmitted from the wireless communication terminal 3 toward the edge terminal 4, the packet monitoring device 1 accumulates it in association with this wireless communication terminal 3 together with the packet arrival time specified by subtracting the measurement date and time included in the sensor information stored in the sensor information packet from the detection date and time of the sensor information packet (S142).

[0045] Here, it is assumed that a momentary interruption occurs in the gateway 5, and the gateway 5 can no longer temporarily receive the sensor information packet wirelessly transmitted from the wireless communication terminal 3 (S143). In this case, when a predetermined retry period elapses without the wireless communication terminal 3 receiving the reception response packet of this sensor information packet from the gateway 5, the wireless communication terminal 3 retransmits the sensor information packet (S144). Then, the gateway 5 in which the momentary interruption has been resolved receives the retransmitted sensor information packet and transmits it to the edge terminal 4 via the hub 6. At this time, the hub 6 mirrors the sensor information packet retransmitted from the wireless communication terminal 3 toward the edge terminal 4 to the packet monitoring device 1 (S145). When the packet monitoring device 1 detects the sensor information packet retransmitted from the wireless communication terminal 3 toward the edge terminal 4, the packet monitoring device 1 stores the detection date and time of the sensor information packet in association with the wireless communication terminal 3 together with the packet arrival time specified by subtracting the measurement date and time included in the sensor information stored in this sensor information packet from this detection date and time (S146). Here, the reference period used for packet monitoring is set to be longer than the time obtained by adding the retry period to the sensor measurement period, and the packet monitoring device 1 detects the retransmitted sensor information packet within the reference period.

[0046] The packet monitoring device 1 monitors the packet arrival time accumulated together with the detection date and time for each wireless communication terminal 3. When detecting a wireless communication terminal 3 in which the newly accumulated packet arrival time exceeds the threshold time registered in the terminal monitoring table (S147), the packet monitoring device 1 determines that a communication failure due to propagation delay has occurred in this wireless communication terminal 3 (S148). Then, the packet monitoring device 1 accumulates communication failure information including the information of the wireless communication terminal 3 in which the communication failure has occurred, the cause of the communication failure "propagation delay", and the detection date and time of the communication failure, and outputs the communication failure information to present it to the user (S149).

[0047] Next, assume that a communication failure occurs in the gateway 5 and it becomes unable to continuously receive the sensor information packets wirelessly transmitted from the wireless communication terminal 3 (S150). In this case, when a predetermined retry period elapses without the wireless communication terminal 3 receiving the reception response packet of this sensor information packet from the gateway 5, the wireless communication terminal 3 retransmits the sensor information packet (S151), but the gateway 5 cannot receive it. Therefore, the retransmitted sensor information packet is not transmitted to the edge terminal 4 either.

[0048] The packet monitoring device 1 monitors the sensor information packets wirelessly transmitted from the wireless communication terminal 3 toward the edge terminal 4 for each wireless communication terminal 3. When the packet monitoring device 1 detects a wireless communication terminal 3 for which no new sensor information packet has been detected even after the reference period registered in the terminal monitoring table has elapsed since the last detection of the sensor information packet (S152), it determines that a communication failure has occurred in this wireless communication terminal 3. Then, the packet monitoring device 1 refers to the communication failure information of the detected wireless communication terminal 3 and checks whether the detection date and time of the communication failure included in the latest communication failure information of this wireless communication terminal 3 are within a predetermined time. If so, it checks whether the cause of the communication failure included in this latest communication failure information is "propagation path delay". Here, assume that the detection date and time of the communication failure included in the latest communication failure information of this wireless communication terminal 3 are within a predetermined time and the cause of the communication failure included in this latest communication failure information is "propagation path delay" (S153).

[0049] In this case, the packet monitoring device 1 determines that the cause of the communication failure that occurred in the wireless communication terminal 3 is not a terminal abnormality of this wireless communication terminal 3 itself but rather that the propagation path delay has deteriorated and a propagation path abnormality has occurred (S154). Then, the packet monitoring device 1 accumulates the communication failure information including the information of the wireless communication terminal 3 in which the communication failure occurred, the cause of the communication failure "propagation path abnormality", and the detection date and time of the communication failure, and outputs the communication failure information to present it to the user (S155).

[0050] Next, the details of the packet monitoring device 1 will be described. Since existing devices can be used for other components (sensor 2, wireless communication terminal 3, gateway 5, hub 6) that make up the wireless data sensing system, detailed descriptions thereof will be omitted.

[0051] FIG. 7 is a schematic functional configuration diagram of the packet monitoring device 1.

[0052] As shown in the figure, the packet monitoring device 1 includes a network interface unit 100, a man-machine interface unit 101, a terminal monitoring table storage unit 102, a packet information storage unit 103, a communication failure information storage unit 104, a first packet monitoring unit 105, a second packet monitoring unit 106, a cause determination unit 107, and a main control unit 108.

[0053] The network interface unit 100 is an interface for connecting to a network (hub 6).

[0054] The man-machine interface unit 101 is an interface for displaying information to the user and receiving various operations from the user, and includes a display device such as an LCD (Liquid Crystal Display), and input devices such as a keyboard and a mouse.

[0055] The terminal monitoring table storage unit 102 stores the above-described terminal monitoring table.

[0056] FIG. 8 is a diagram schematically showing an example of the registration contents of the terminal monitoring table 1020 stored in the terminal monitoring table storage unit 102.

[0057] As shown in the figure, in the terminal monitoring table 1020, for each wireless communication terminal 3 to be monitored (hereinafter referred to as the monitored terminal), a record 1021 of monitoring information in which various information used for packet monitoring is registered is stored. The record 1021 of monitoring information has a field 1022 in which the terminal ID, which is the identification information of the monitored terminal, is registered, a field 1023 in which the address information of the monitored terminal is registered, a field 1024 in which the sensor measurement period of the monitored terminal is registered, a field 1025 in which the reference period of the monitored terminal is registered, a field 1026 in which the threshold time of the monitored terminal is registered, and a field 1027 in which the connection relationship of the monitored terminal is registered. Further, the field 1027 has a sub-field 1028 in which the terminal ID of the parent terminal of the monitored terminal is registered and a sub-field 1029 in which the terminal ID of the child terminal of the monitored terminal is registered.

[0058] In the packet information storage unit 103, for each monitored terminal, packet information including the detection date and time of the sensor information packet and the packet arrival time is stored.

[0059] FIG. 9 is a diagram schematically showing an example of the registered content of the packet information storage unit 103.

[0060] As shown in the figure, in the packet information storage unit 103, for each monitored terminal, a packet information table 1030 is stored. In the packet information table 1030, each time the packet monitoring device 1 detects a sensor information packet, a record 1031 of packet information is added (stored). The record 1031 of packet information has a field 1032 in which the detection date and time of the sensor information packet is registered and a field 1033 in which the packet arrival time of the sensor information packet is registered. As described above, the packet arrival time is calculated by subtracting the measurement date and time included in the sensor information stored in this sensor information packet from the detection date and time of the sensor information packet.

[0061] Each time a communication failure is detected, the communication failure information storage unit 104 stores communication failure information including the monitored terminal in which the communication failure has occurred and information regarding the cause thereof.

[0062] FIG. 10 is a diagram schematically showing an example of the registered content of the communication failure information storage unit 104.

[0063] As shown in the figure, each time the packet monitoring device 1 detects a communication failure, a record 1040 of communication failure information is added (stored) in the communication failure information storage unit 104. The record 1040 of communication failure information has a field 1041 in which the detection date and time of the communication failure are registered, a field 1042 in which the terminal ID of the monitored terminal in which the communication failure has occurred is registered, and a field 1043 in which the cause of the communication failure (any one of terminal abnormality, propagation path delay, and propagation path abnormality) is registered.

[0064] The first packet monitoring unit 105 monitors, for each monitored terminal, whether or not the elapsed time from the detection date and time registered in the field 1032 of the record 1031 of the latest packet information stored in the packet information table 1030 of the monitored terminal registered in the packet information storage unit 103 exceeds the reference period registered in the field 1025 of the record 1021 of the monitoring information of the monitored terminal stored in the terminal monitoring table 1020.

[0065] The second packet monitoring unit 106 monitors, for each monitored terminal, whether or not the packet arrival time registered in the field 1033 of the record 1031 of the latest packet information stored in the packet information table 1030 of the monitored terminal registered in the packet information storage unit 103 exceeds the threshold time registered in the field 1026 of the record 1021 of the monitoring information of the monitored terminal stored in the terminal monitoring table 1020.

[0066] Based on the monitoring results of the first packet monitoring unit 105 and the second packet monitoring unit 106, the cause determination unit 107 determines the cause of the communication failure that has occurred in the monitored terminal and stores the communication failure information in the communication failure information storage unit 104.

[0067] Then, the main control unit 108 comprehensively controls each part 100 to 107 of the packet monitoring device 1. Also, when the main control unit 108 receives a terminal setting information packet from the hub 6 via the network interface unit 100, it acquires terminal list information from the edge terminal 4 and registers the terminal monitoring table 1020 in the terminal monitoring table storage unit 102. At the same time, according to the network connection information packet received from the hub 6 via the network interface unit 100, it updates the terminal monitoring table 1020. Furthermore, the main control unit 108 updates the packet information table 1030 of the monitoring target terminal, which is the source of this sensor information packet, among the packet information tables 1030 registered in the packet information storage unit 103 according to the sensor information packet received from the hub 6 via the network interface unit 100.

[0068] Note that the functional configuration of the packet monitoring device 1 shown in FIG. 7 may be realized hard by an integrated logic IC such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array), or may be realized software by a computer such as a DSP (Digital Signal Processor). Alternatively, in a general-purpose computer such as a PC (Personal Computer) equipped with a CPU (Central Processing Unit), a memory, an auxiliary storage device, and a communication interface, each function may be realized as a process by the CPU loading a predetermined program from the auxiliary storage device onto the memory and executing it.

[0069] FIG. 11 is a flowchart for explaining the packet monitoring preparation process of the packet monitoring device 1.

[0070] This process starts when the main control unit 108 receives, via the network interface unit 100, the terminal setting information packet mirrored to the packet monitoring device 1 by the hub 6.

[0071] First, the main control unit 108 transmits a terminal list information request to the edge terminal 4 via the network interface unit 100 (S200), and acquires, from the edge terminal 4, the terminal list information including the terminal ID, address information, and sensor measurement period of each monitoring target terminal (S201). Then, for each monitoring target terminal included in the terminal list information, the main control unit 108 creates a terminal monitoring table 1020 having a record 1021 of monitoring information and stores it in the terminal monitoring table storage unit 102. And, the terminal ID, address information, and sensor measurement period of the corresponding monitoring target terminal are registered in the fields 1022 to 1024 of each record 1021 of the terminal monitoring table 1020. Also, a predetermined time longer than a predetermined retry period is added to the sensor measurement period of the corresponding monitoring target terminal to calculate a reference period, and this reference period is registered in the field 1025 of each record 1021 (S202). Note that the fields 1024 and 1025 of the record 1021 of the monitoring target terminal (monitoring target terminal for which the sensor measurement period is not set) not included in the terminal list information are left as blank (Null data).

[0072] Next, when the main control unit 108 receives, via the network interface unit 100, the network connection information packet mirrored to the packet monitoring device 1 by the hub 6 (YES in S203), the connection relationship (terminal IDs of the parent terminal and child terminal) specified by the network connection information stored in this network connection information packet is registered in the field 1027 of the record 1021 of the terminal monitoring table 1020 stored in the terminal monitoring table storage unit 102 to update the terminal monitoring table 1020 (S204). At this time, if a threshold time is registered in the field 1026 of the record 1021 of the network connection information packet transmission source, this threshold time is cleared.

[0073] Then, the main control unit 108 newly creates a packet information table 1030 for the network connection information packet transmission source and registers it in the packet information storage unit 103, and starts accumulating the packet information of the network connection information packet transmission source (S205).

[0074] That is, when the main control unit 108 receives a sensor information packet from the network connection information packet transmission source, which is mirrored to the packet monitoring device 1 by the hub 6, via the network interface unit 100, it adds a record 1031 of the packet information to the packet information table 1030 of this transmission source. Then, it registers the reception date and time of the sensor information packet as the detection date and time in the field 1032 of the added record 1031, and registers in the field 1033 the packet arrival time calculated by subtracting the measurement date and time included in the sensor information stored in this sensor information packet from this detection date and time.

[0075] Also, when the main control unit 108 refers to the packet information storage unit 103 and detects a packet information table 1030 in which records 1031 of packet information are accumulated by a predetermined number or more (YES in S206), it refers to the terminal monitoring table 1020 in the terminal monitoring table storage unit 102 and checks whether a threshold time is registered in the field 1026 of the record 1021 of the monitoring target terminal associated with this packet information table 1030 (S207). If the threshold time is not registered (NO in S207), it calculates the average value of the packet arrival times (excluding the packet arrival times longer than a predetermined retry period) registered in the field 1033 of the records 1031 of the packet information accumulated in this packet information table 1030 by a predetermined number or more. Then, it calculates the threshold time by adding a predetermined time shorter than the predetermined retry period to the average value of the packet arrival times, and registers the calculated threshold time in the field 1026 of the record 1021 of this monitoring target terminal. Thereby, the terminal monitoring table 1020 is updated (S208).

[0076] FIG. 12 and FIG. 13 are flowcharts for explaining the packet monitoring process of the packet monitoring device 1.

[0077] This flow is executed for each monitored terminal registered in the terminal monitoring table 1020 after the terminal monitoring table 1020 is stored in the terminal monitoring table storage unit 102.

[0078] The first packet monitoring unit 105 refers to the record 1021 of the monitored terminal registered in the terminal monitoring table 1020. If a reference period is registered in the field 1025 of this record 1021 (YES in S300), it refers to the packet information table 1030 of the monitored terminal stored in the packet information storage unit 103, and determines whether the reference period has elapsed from the detection date and time registered in the field 1032 of the record 1031 of the latest packet information (S301). Here, if no reference period is registered in the field 1025 of the record 1021 of the monitored terminal registered in the terminal monitoring table 1020 (NO in S300), or if the reference period has not elapsed from the detection date and time of the latest sensor information packet (NO in S301), the process proceeds to S311.

[0079] On the other hand, if the reference period has elapsed from the detection date and time of the latest sensor information packet (YES in S301), the first packet monitoring unit 105 determines that a communication failure has occurred in the monitored terminal, and notifies the cause determination unit 107 of the terminal ID of this monitored terminal.

[0080] In response to this, the cause determination unit 107 refers to the communication failure information storage unit 104 and searches for a record 1040 of the latest communication failure information in which the notified terminal ID is registered in the field 1042, and the detection date and time of the communication failure registered in the field 1041 is within a predetermined time from the detection date and time of the latest sensor information packet, and the cause of the communication failure registered in the field 1043 is "propagation path delay". Thereby, it is determined whether or not a communication failure caused by a propagation path delay has occurred in this monitored terminal within a predetermined time from the detection date and time of the latest sensor information packet (S302). And when a communication failure caused by a propagation path delay has occurred in the monitored terminal within a predetermined time from the detection date and time of the latest sensor information packet (YES in S302), the cause determination unit 107 determines that the cause of the communication failure that has occurred in the monitored terminal this time is not a terminal abnormality of the monitored terminal itself, but rather that the propagation path delay has deteriorated and a propagation path abnormality has occurred (S303). In this case, the cause determination unit 107 adds to the record 1040 of the communication failure information in the communication failure information storage unit 104, registers the detection date and time of the latest sensor information packet as the detection date and time of the communication failure in the field 1041, and registers the terminal ID of the monitored terminal and the cause of the communication failure "propagation path abnormality" in the fields 1042 and 1043. Further, the record 1040 of this communication failure information is notified to the main control unit 108. In response to this, the main control unit 108 outputs communication failure information including the detection date and time of the communication failure registered in the record 1040 of the communication failure information, the terminal ID of the monitored terminal, and the cause of the communication failure "propagation path abnormality" to the man-machine interface unit 101 to notify the user of the occurrence of the communication failure (S304).

[0081] On the other hand, if no communication failure due to propagation delay has occurred within a predetermined time from the detection date and time of the latest sensor information packet (NO in S302), the cause determination unit 107 refers to the record 1021 of the monitored terminal registered in the terminal monitoring table 1020, and determines whether the terminal ID of the parent terminal is registered in the sub-field 1028 of the field 1027 of this record 1021 (S305). Then, if the terminal ID of the parent terminal is registered (YES in S305), the cause determination unit 107 waits for a predetermined waiting time to elapse (S306), and then refers to the communication failure information storage unit 104 to search for a record 1040 of communication failure information in which the terminal ID of the parent terminal is registered in the field 1042, the detection date and time of the communication failure registered in the field 1041 is within a predetermined time from the detection date and time of the latest sensor information packet, and the cause of the communication failure registered in the field 1043 is "terminal abnormality". Thereby, it is determined whether a communication failure due to terminal abnormality has occurred in the parent terminal within a predetermined time from the detection date and time of the latest sensor information packet (S307). And if a communication failure due to terminal abnormality has occurred in the parent terminal within a predetermined time from the detection date and time of the latest sensor information packet (YES in S307), the cause determination unit 107 determines that there is no abnormality in the monitored terminal itself because the cause of the communication failure that has occurred in the monitored terminal this time is likely due to the "terminal abnormality" of the parent terminal. Thereafter, the process proceeds to S311.

[0082] On the other hand, if no communication failure caused by a terminal abnormality has occurred in the parent terminal within a predetermined time from the detection date and time of the latest sensor information packet (NO in S307), or if the terminal ID of the parent terminal is not registered in the sub - field 1028 of the field 1027 of the record 1021 of the monitored terminal (NO in S305), the cause determination unit 107 determines that the cause of the communication failure that occurred in the monitored terminal this time is the "terminal abnormality" of the monitored terminal (S309). In this case, the cause determination unit 107 adds it to the record 1040 of the communication failure information in the communication failure information storage unit 104, registers the detection date and time of the latest sensor information packet as the detection date and time of the communication failure in the field 1041 of this record 1040, and registers the terminal ID of the monitored terminal and the cause of the communication failure "terminal abnormality" in the fields 1042 and 1043. Also, the record 1040 of this communication failure information is notified to the main control unit 108. In response to this, the main control unit 108 outputs communication failure information including the detection date and time of the communication failure registered in the record 1040 of the communication failure information, the terminal ID of the monitored terminal, and the cause of the communication failure "terminal abnormality" to the man - machine interface unit 101, and notifies the user of the occurrence of the communication failure (S310).

[0083] In S311, the second packet monitoring unit 106 refers to the record 1021 of the monitored terminal registered in the terminal monitoring table 1020. If the threshold time is registered in the field 1026 of this record 1021 (YES in S311), it refers to the packet information table 1030 of the monitored terminal stored in the packet information storage unit 103, and determines whether the packet arrival time of the latest sensor information packet registered in the field 1033 of the record 1031 of the latest packet information exceeds the threshold time (S312). Here, if the threshold time is not registered in the field 1026 of the record 1021 of the monitored terminal (NO in S311), or if the packet arrival time of the latest sensor information packet does not exceed the threshold time (NO in S312), the process returns to S300.

[0084] On the other hand, when the packet arrival time of the latest sensor information packet exceeds the threshold time (YES in S312), the second packet monitoring unit 106 determines that a communication failure has occurred in the monitored terminal, and notifies the terminal ID of this monitored terminal to the cause determination unit 107. In response to this, the cause determination unit 107 determines that the cause of the communication failure that has occurred in the monitored terminal this time is propagation delay (S313). Then, the cause determination unit 107 adds it to the record 1040 of the communication failure information in the communication failure information storage unit 104, and registers the detection date and time of the latest sensor information packet as the detection date and time of the communication failure in the field 1041 of this record 1040. At the same time, the terminal ID of the monitored terminal and the cause of the communication failure, "propagation delay", are registered in the fields 1042 and 1043. In addition, the record 1040 of this communication failure information is notified to the main control unit 108. In response to this, the main control unit 108 outputs the communication failure information including the detection date and time of the communication failure registered in the record 1040 of the communication failure information, the terminal ID of the monitored terminal, and the cause of the communication failure, "propagation delay", to the man-machine interface unit 101, and notifies the user of the occurrence of the communication failure (S314). Then, it returns to S300.

[0085] The above is the description of one embodiment of the present invention.

[0086] In this embodiment, the packet monitoring device 1 monitors sensor information packets transmitted from the gateway 5 to the edge terminal 4 for each monitored terminal. Then, for a certain monitored terminal, if no sensor information packet is detected even after a reference period determined according to the sensor measurement period of this monitored terminal has elapsed, it is determined that a communication failure caused by a terminal abnormality of this monitored terminal has occurred. Further, even when a sensor information packet is detected within the reference period, if the packet arrival time, which is the difference between the measurement date and time of the sensor value included in the sensor information stored in this sensor information packet and the detection date and time of this sensor information packet in the packet monitoring device 1, exceeds a threshold time determined based on past packet arrival times, it is determined that a communication failure caused by a propagation path delay has occurred in this monitored terminal. Therefore, even when the sensor information packet is not missing, a communication failure can be detected and its cause (propagation path delay) can be specified. Also, when a communication failure in which the sensor information packet is missing occurs, the cause can be specified as a terminal abnormality of the monitored terminal. Thus, according to this embodiment, the cause of a failure occurring in the wireless data sensing system can be determined more accurately.

[0087] Further, in this embodiment, for a monitored terminal in which no sensor information packet is detected within the reference period, if it is determined that a communication failure caused by a propagation path delay has occurred within a predetermined time, it is determined that the cause of the communication failure that has occurred in this monitored terminal is not a terminal abnormality of this monitored terminal itself, but rather a propagation path abnormality has occurred due to deterioration of the propagation path delay. Therefore, the cause of the communication failure can be determined more accurately.

[0088] In addition, in this embodiment, the monitored terminals are wirelessly connected in a tree structure. When a child terminal exists, it has a function of relaying packets between this child terminal and the gateway 5 or, if a parent terminal exists, between the child terminal and the parent terminal. And for a monitored terminal for which no sensor information packet has been detected within a reference period, if a parent terminal exists and a communication failure caused by a terminal abnormality of the parent terminal has occurred within a predetermined time, then this time, since it is highly likely that the cause of the communication failure that occurred in the monitored terminal is the terminal abnormality of the parent terminal, the monitored terminal is determined not to have a terminal abnormality but to be normal without abnormality. Therefore, false determination of terminal abnormalities can be reduced.

[0089] In addition, in this embodiment, when the packet arrival time of the sensor information packet transmitted from the monitored terminal to the edge terminal 4 exceeds the threshold time, the packet monitoring device 1 determines that a communication failure caused by a propagation path delay has occurred in this monitored terminal. Therefore, even for a monitored terminal for which no sensor measurement period is set, a communication failure caused by a propagation path delay can be detected.

[0090] Note that the present invention is not limited to the above-described embodiment, and numerous modifications are possible within the scope of the gist thereof.

[0091] For example, in the above-described embodiment, for each monitored terminal, when a record 1031 of a predetermined number or more of packet information has been accumulated in the packet information table 1030 of the monitored terminal, the threshold time is determined using the average value of the packet arrival times registered in these records 1031 (S206 to S208 in FIG. 11). Therefore, for a monitored terminal for which the number of accumulated records 1031 of packet information has not reached the predetermined number, the threshold time is not set, and thus monitoring of the packet arrival time using the threshold time cannot be performed (S311 to S314 in FIG. 13). Therefore, for such a monitored terminal, the packet arrival time may be monitored using a provisional threshold time.

[0092] That is, even if the predetermined number has not been reached in the packet information table 1030 of the monitoring target terminal, if the record 1031 of the packet information has been accumulated, a provisional threshold time may be determined to be longer than the time obtained by adding the retry period to the average value of the packet arrival times (excluding packet arrival times longer than the predetermined retry period) registered in the accumulated record 1031, and the packet arrival time may be monitored using this provisional threshold time.

[0093] Also, for example, when the connection relationship of the monitoring target terminal is changed and immediately after a network connection information packet is transmitted from this monitoring target terminal to the edge terminal 4, the accumulation of the packet information of this monitoring target terminal has just started, and there may be a case where no record 1031 of the packet information is accumulated in the packet information table 1030 of this monitoring target terminal. In this case, if there is a parent terminal for the monitoring target terminal after this connection relationship change and a threshold time is set for the parent terminal, a provisional threshold time may be determined to be longer than the time obtained by adding the packet transmission time between the monitoring target terminal and the parent terminal to the threshold time of the parent terminal, and the packet arrival time may be monitored using this provisional threshold time. Here, the packet transmission time between the monitoring target terminal and the parent terminal is such that each time the wireless communication terminal 3 transmits (relays) the sensor information packet of the child terminal, the transmission date and time of the own wireless communication terminal 3 are added, so that the packet monitoring device 1 can calculate from the difference between the measurement date and time of the sensor value included in the sensor information stored in the sensor information packet with the monitoring target terminal as the transmission source and the transmission date and time of the parent terminal added to this sensor information packet.

[0094] Also, in the above embodiment, the packet monitoring device 1 is provided with the man-machine interface unit 101 and outputs the communication failure information to the man-machine interface unit 101, but the present invention is not limited to this. The communication failure information may be output to a management terminal connected to the hub 6 via the network interface unit 100. In this case, the man-machine interface unit 101 may be omitted.

Explanation of Reference Numerals

[0095] 1: Packet monitoring device 2, 2-1 to 2-7: Sensors 3, 3-1 to 3-7: Wireless communication terminals 4: Edge terminal 5: Gateway 6: Hub 100: Network interface section 101: Man-machine interface section 102: Terminal monitoring table storage section 103: Packet information storage section 104: Communication failure information storage section 105: First packet monitoring section 106: Second packet monitoring section 107: Cause determination section 108: Main control section

Claims

1. A plurality of wireless communication terminals that are connected to a sensor and wirelessly transmit a sensor information packet storing sensor information including a sensor value of the sensor and its measurement date and time, an edge terminal that collects and manages the sensor information of each of the sensors, and a gateway that receives the sensor information packet wirelessly transmitted from the plurality of wireless communication terminals and transmits it to the edge terminal. In a wireless data sensing system having the above components, a packet monitoring device that monitors the sensor information packet, For each of the wireless communication terminals, a first packet monitoring means for monitoring whether the sensor information packet transmitted from the wireless communication terminal to the edge terminal is detected within a reference period determined according to the measurement period of the sensor connected to the wireless communication terminal. For each of the wireless communication terminals, a second packet monitoring means for monitoring whether a packet arrival time, which is a difference between the measurement date and time included in the sensor information stored in the sensor information packet transmitted from the wireless communication terminal to the edge terminal and the detection date and time by the packet monitoring device, is within a threshold time determined based on the past packet arrival time. When the first packet monitoring means determines that an abnormality has occurred in the wireless communication terminal in which the sensor information packet has not been detected within the reference period, and when the second packet monitoring means determines that the packet arrival time exceeds the threshold time for the wireless communication terminal in which the sensor information packet has been detected within the reference period by the first packet monitoring means, a cause determination means for determining that a delay has occurred in the propagation path is provided. The plurality of wireless communication terminals are wirelessly connected in a tree structure with the gateway at the top. The wireless communication terminal, The sensor information packet including the sensor information of the sensor connected to the wireless communication terminal, and the sensor information packet received from the other wireless communication terminals located downstream of the wireless communication terminal in the tree structure are transmitted to the other wireless communication terminals located upstream of the wireless communication terminal in the tree structure if there are other wireless communication terminals, and are transmitted to the gateway if there are no other wireless communication terminals. The cause determination means For the wireless communication terminal in which the sensor information packet is not detected within the reference period by the first packet monitoring means, if it is determined that there are other wireless communication terminals located upstream of the wireless communication terminal in the tree structure and an abnormality has occurred in the other wireless communication terminal within a predetermined time, the wireless communication terminal is determined to be normal. A packet monitoring device characterized by the above.

2. The packet monitoring device according to claim 1, The cause determination means For the wireless communication terminal in which the sensor information packet is not detected within the reference period by the first packet monitoring means, if it is determined that a delay has occurred in the propagation path within a predetermined time, it is determined that an abnormality has occurred in the propagation path rather than the wireless communication terminal. A packet monitoring device characterized by the above.

3. The packet monitoring device according to claim 1 or 2, The wireless communication terminal Adds the transmission date and time of the wireless communication terminal itself to the sensor information packet received from the other wireless communication terminals located downstream of the wireless communication terminal in the tree structure and transmits it. The second packet monitoring means When the network connection relationship is changed and the sensor information packet transmitted from the wireless communication terminal in which the past packet arrival time after the change has not been accumulated is detected by the edge terminal, if there are other wireless communication terminals located upstream of the wireless communication terminal in the tree structure, based on the threshold time of the other wireless communication terminal and the packet transmission time which is the difference between the measurement date and time of the sensor value included in the sensor information stored in the sensor information packet and the transmission date and time of the other wireless communication terminal added to the sensor information packet, the threshold time of the wireless communication terminal is tentatively determined. A packet monitoring device characterized by the above. In a wireless data sensing system having a plurality of wireless communication terminals that are connected to sensors and wirelessly transmit sensor information packets storing sensor values of the sensors and their measurement dates and times, and an edge terminal that collects and manages the sensor information of each of the sensors, a packet monitoring device that monitors the sensor information packets, For each wireless communication terminal, first packet monitoring means for monitoring whether the sensor information packet transmitted from the wireless communication terminal to the edge terminal is detected within a reference period determined according to the measurement period of the sensor connected to the wireless communication terminal; For each wireless communication terminal, second packet monitoring means for monitoring whether a packet arrival time, which is the difference between the measurement date and time included in the sensor information stored in the sensor information packet transmitted from the wireless communication terminal to the edge terminal and the detection date and time by the packet monitoring device, is within a threshold time determined based on the past packet arrival time; Cause determination means for determining that an abnormality has occurred in the wireless communication terminal in which the sensor information packet has not been detected within the reference period by the first packet monitoring means, and determining that a delay has occurred in the propagation path when it is determined by the second packet monitoring means that the packet arrival time exceeds the threshold time for the wireless communication terminal in which the sensor information packet has been detected within the reference period by the first packet monitoring means. The first packet monitoring means excludes the wireless communication terminal for which the measurement period is not set from the monitoring target, The cause determination means for the wireless communication terminal excluded from the monitoring target of the first packet monitoring means, when the packet arrival time of the sensor information packet transmitted from the wireless communication terminal to the edge terminal exceeds the threshold time by the second packet monitoring means, determines that a delay has occurred in the propagation path A packet monitoring device characterized by the above.

5. In a wireless data sensing system having a plurality of wireless communication terminals that are connected to sensors and wirelessly transmit sensor information packets storing sensor values of the sensors and their measurement dates and times, and an edge terminal that collects and manages the sensor information of each of the sensors, a packet monitoring device that monitors the sensor information packets, for each wireless communication terminal, first packet monitoring means for monitoring whether the sensor information packet transmitted from the wireless communication terminal to the edge terminal is detected within a reference period determined according to the measurement period of the sensor connected to the wireless communication terminal; for each wireless communication terminal, second packet monitoring means for monitoring whether a packet arrival time, which is a difference between the measurement date and time included in the sensor information stored in the sensor information packet transmitted from the wireless communication terminal to the edge terminal and the detection date and time by the packet monitoring device, is within a threshold time determined based on the past packet arrival time; cause determination means for determining that an abnormality has occurred in the wireless communication terminal for which the sensor information packet has not been detected within the reference period by the first packet monitoring means, and for determining that a delay has occurred in the propagation path when it is determined by the second packet monitoring means that the packet arrival time exceeds the threshold time for the wireless communication terminal for which the sensor information packet has been detected within the reference period by the first packet monitoring means; Terminal list information acquisition means for acquiring terminal list information including setting information including the measurement periods of the plurality of wireless communication terminals from the edge terminal A packet monitoring device characterized by the above.

6. In a wireless data sensing system having a plurality of wireless communication terminals that are connected to sensors and wirelessly transmit sensor information packets storing sensor values of the sensors and their measurement dates and times, an edge terminal that collects and manages sensor information of each of the sensors, and a gateway that receives the sensor information packets wirelessly transmitted from the plurality of wireless communication terminals and transmits them to the edge terminal, as a packet monitoring device for monitoring the sensor information packets, a program that causes a computer to function, First packet monitoring means for monitoring, for each of the wireless communication terminals, whether or not the sensor information packet transmitted from the wireless communication terminal to the edge terminal is detected within a reference period determined according to the measurement period of the sensor connected to the wireless communication terminal Second packet monitoring means for monitoring, for each of the wireless communication terminals, whether or not a packet arrival time, which is a difference between the measurement date and time of the sensor value included in the sensor information stored in the sensor information packet transmitted from the wireless communication terminal to the edge terminal and the detection date and time in the packet monitoring device, is within a threshold time determined based on the past packet arrival times, and Causing the computer to function as cause determination means for determining that an abnormality has occurred in the wireless communication terminal in which the sensor information packet has not been detected within the reference period by the first packet monitoring means, and determining that a delay has occurred in the propagation path when it is determined by the second packet monitoring means that the packet arrival time of the sensor information packet exceeds the threshold time for the wireless communication terminal in which the sensor information packet has been detected within the reference period by the first packet monitoring means, The plurality of wireless communication terminals are wirelessly connected in a tree structure with the gateway at the top level, The wireless communication terminal is The sensor information packet including the sensor information of the sensor connected to the wireless communication terminal, and the sensor information packet received from another wireless communication terminal located downstream of the wireless communication terminal in the tree structure are transmitted to another wireless communication terminal located upstream of the wireless communication terminal in the tree structure if there is such another wireless communication terminal, and are transmitted to the gateway if there is no such another wireless communication terminal. The cause determination means For the wireless communication terminal in which the sensor information packet has not been detected within the reference period by the first packet monitoring means, if it is determined that there is another wireless communication terminal located upstream of the wireless communication terminal in the tree structure and an abnormality has occurred in the other wireless communication terminal within a predetermined time, then the wireless communication terminal is determined to be normal. A program characterized by the above.

7. In a wireless data sensing system having a plurality of wireless communication terminals that are wirelessly connected to sensors and wirelessly transmit sensor information packets storing sensor values of the sensors and their measurement dates and times, an edge terminal that collects and manages the sensor information of each of the sensors, and a gateway that receives the sensor information packets wirelessly transmitted from the plurality of wireless communication terminals and transmits them to the edge terminal, a packet monitoring method for monitoring the sensor information packets, The plurality of wireless communication terminals are wirelessly connected in a tree structure with the gateway at the top, and a hub is arranged between the gateway and the edge terminal to mirror the sensor information packet transmitted from the gateway to the edge terminal to a packet monitoring device. The wireless communication terminal The sensor information packet including the sensor information of the sensor connected to the wireless communication terminal, and the sensor information packet received from the other wireless communication terminals located downstream of the wireless communication terminal in the tree structure are transmitted to the other wireless communication terminals located upstream of the wireless communication terminal in the tree structure if there are any, and if not, are transmitted to the gateway. The packet monitoring device For each of the wireless communication terminals, monitors whether the sensor information packet transmitted from the wireless communication terminal to the edge terminal is detected within a reference period determined according to the measurement period of the sensor connected to the wireless communication terminal, and for each of the wireless communication terminals, monitors whether a packet arrival time, which is the difference between the measurement date and time of the sensor value included in the sensor information stored in the sensor information packet transmitted from the wireless communication terminal to the edge terminal and the detection date and time in the packet monitoring device, is within a threshold time determined based on the past packet arrival time. For the wireless communication terminal in which the sensor information packet is not detected within the reference period, it is determined that an abnormality has occurred in the wireless communication terminal. However, if there are other wireless communication terminals located upstream of the wireless communication terminal in the tree structure and it is determined that an abnormality has occurred in the other wireless communication terminal within a predetermined time, then the wireless communication terminal is determined to be normal. For the wireless communication terminal in which the sensor information packet is detected within the reference period, when it is determined that the packet arrival time of the sensor information packet exceeds the threshold time, it is determined that a delay has occurred in the propagation path. A packet monitoring method characterized by the above.

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