JP2019012923A - Wireless communication system - Google Patents

Abstract

To efficiently utilize a plurality of communication paths in a wireless communication system.SOLUTION: A wireless communication system 100 includes a plurality of communication terminals connected to each other by wireless communication. The plurality of communication terminals includes a data station 10 and a plurality of repeaters 20 that transmits detection values of a sensor 30 to the data station 10. The sensor 30 includes sensors 30d, 30h, and 30n with high detection importance and sensors 30a, 30b, ... with low detection importance. The data station 10 communicates with repeaters 20a, 20b, ... that transmit detection values of the sensors 30a, 30b, ... of low importance through a predetermined first communication path, and communicates with repeaters 20e, 20h, and 20k that transmit detection values of the sensors 30d, 30h, and 30n with high importance through the first communication path and a second communication path different from the first communication path.SELECTED DRAWING: Figure 1

Description

  The technology disclosed herein relates to a wireless communication system.

  Conventionally, a wireless communication system including a plurality of communication terminals is known. The wireless communication system described in Patent Literature 1 includes a plurality of communication terminals connected to each other by wireless communication. A predetermined communication path is set between these communication terminals. Usually, communication between a plurality of communication terminals is performed via a main communication path. However, when an abnormality occurs in the main communication path, communication is performed via another communication path.

JP 2009-253359 A

  By the way, in the wireless communication system as disclosed in Patent Document 1, when an abnormality occurs in the main communication path, communication is always performed through another communication path. For example, some communication anomalies are temporary and can be resolved in the future. Further, depending on the communication contents, there is a case where it is not always necessary to execute communication through another communication path. As described above, when an abnormality occurs in the main communication path, it is not always efficient to perform communication using another communication path.

  The technology disclosed herein has been made in view of such a point, and an object thereof is to efficiently use a plurality of communication paths in a wireless communication system.

  The wireless communication system disclosed herein includes a plurality of communication terminals connected to each other by wireless communication, and the plurality of communication terminals transmit a master unit and a plurality of slave units that transmit sensor detection values to the master unit. The sensor includes a sensor having a high importance of detection and a sensor having a low importance of detection, and the parent device transmits the detection value of the sensor having the low importance. While communicating with the machine via a predetermined first communication path, the slave that transmits the detection value of the sensor having a high importance is different from the first communication path and the first communication path. Communication is performed via two communication paths.

  According to the wireless communication system disclosed herein, a plurality of communication paths can be efficiently used in the wireless communication system.

FIG. 1 is a schematic diagram of a wireless communication system having a tree structure corresponding to a first communication path. FIG. 2 is a block diagram of the data station. FIG. 3 shows an important level table. FIG. 4 is a block diagram of the repeater. FIG. 5 is a block diagram of the sensor. FIG. 6 is a diagram illustrating the first tree table. FIG. 7 is a schematic diagram of a wireless communication system having a tree structure corresponding to the second communication path. FIG. 8 is a diagram illustrating the second tree table. FIG. 9 is a diagram illustrating a first routing table of the repeater 20a. FIG. 10 is a diagram illustrating a second routing table of the repeater 20a. FIG. 11 is a diagram illustrating a sensor table. FIG. 12 is a diagram showing a communication schedule. FIG. 13 is a flowchart showing the data station process in the collection process. FIG. 14 is a flowchart showing the processing of the repeater in the collection processing. FIG. 15 is a flowchart showing the subroutine of the first reply process. FIG. 16 is a flowchart showing the subroutine of the second reply process. FIG. 17 is a flowchart illustrating the processing of a relay processing subroutine. FIG. 18 is a sequence diagram showing a flow of processing in the specific slot of the relay 20k when the detection value can be normally transmitted in the first specific slot. FIG. 19 is a sequence diagram showing a flow of processing in the specific slot of the relay 20k when the detection value cannot be normally transmitted in the first specific slot.

  Hereinafter, exemplary embodiments will be described in detail with reference to the drawings.

  FIG. 1 is a schematic diagram of a wireless communication system 100. The wireless communication system 100 includes a data station 10, a plurality of relay devices 20, and a plurality of sensors 30. The data station 10, the repeater 20, and the sensor 30 are communication terminals that perform wireless communication with each other and autonomously construct a network. In the wireless communication system 100, a multi-hop wireless network is formed. The data station 10 functions as a parent device, and the relay device 20 functions as a child device. Basically, the data station 10 communicates with the relay machine 20, and the sensor 30 communicates with the relay machine 20. The number of sensors 30 is larger than that of the repeater 20. The data station 10 and the repeater 20 constitute a tree-type network topology with the data station 10 as a vertex (the highest level). In the present specification, in the network, the data station 10 side is the upstream side or the upper side, and the end side of the tree is the downstream side or the lower side. Further, when the data station 10, the repeater 20, and the sensor 30 are not distinguished, they may be simply referred to as communication terminals. In addition, when distinguishing each relay machine 20, an alphabet is added after the reference numeral “20”. Similarly, when distinguishing each sensor 30, it distinguishes by attaching | subjecting an alphabet after code | symbol "30".

  In the wireless communication system 100, the sensor 30 detects a predetermined physical quantity of an object, and the detected value, that is, detected data is collected in the data station 10 via the relay device 20. In the example in the present disclosure, the wireless communication system 100 is installed in a factory having a steam system. The steam system has a plurality of steam traps T and a plurality of motors M (shown one by one in FIG. 1). The object is a steam trap T or a motor M. The sensor 30 detects the vibration and temperature of the steam trap T or the motor M.

<Data station configuration>
FIG. 2 is a block diagram of the data station 10. The data station 10 establishes a communication path of the wireless communication system 100 and collects and manages detection values of the sensor 30. Further, the data station 10 is connected to a host server 90 (FIG. 1) or the like via an external network or the like. The data station 10 transfers the detection value of the sensor 30 to the server 90 as necessary.

  The data station 10 includes a CPU 11, a memory 12, a storage unit 13, a wireless communication circuit 14, a timing circuit 15, a higher level interface unit 16, and a power supply circuit 17.

  The storage unit 13 stores various programs and various information. The CPU 11 performs various processes by reading and executing various programs from the storage unit 13. For example, in the storage unit 13, a program for forming a network communication path, a program for collecting detection values of the sensors 30, a tree table for defining a tree structure of the network, and which relay device 20 each sensor 30 is assigned to A sensor table that defines whether it is connected, a routing table that defines a route to the final destination, a program for creating a routing table from the tree table, schedule information that defines a schedule for communicating with the relay device 20, and The collected detection values and the like are stored.

  Further, the storage unit 13 stores an importance level that is an index of the importance of detection by the sensor 30 as information on the importance of the sensor 30. For example, the important level of each sensor 30 is acquired from the server 90 by the data station 10.

  The importance level indicates the necessity for detection by the sensor 30. The higher the critical level, the higher the need for detection. For example, the important level includes the risk when the object of the sensor 30 becomes abnormal, the frequency at which the object of the sensor 30 becomes abnormal (for example, the failure rate), and the object of the sensor 30 is regularly inspected or maintained. In the case of the inspection, it is set based on the inspection frequency or maintenance frequency. Specifically, since the steam trap T or the motor M arranged at an important position in the steam system has a high risk of being given to the steam system when an abnormality occurs, the steam trap T or the motor M is provided. The important level of the sensor 30 is set high. Further, since the steam trap T or the motor M that has been in an abnormal state several times in the past is likely to be in an abnormal state again, the importance of the sensor 30 provided in such a steam trap T or the motor M is important. The level is set high. Further, when the steam trap T or the motor M is regularly inspected or maintained, the steam trap T or the motor M having a low frequency of inspection or maintenance has low reliability. The important level of the sensor 30 provided in is set high.

  The storage unit 13 stores an important level table as shown in FIG. In the upper column of the important level table, the target sensor 30 is described, and in the lower column, the important level of each sensor 30 is defined. In the example of FIG. 3, the importance level is set in two stages. The critical levels of the sensors 30d, 30h, and 30n are high at “2”, and the critical levels of the other sensors 30 are low at “1”.

  The wireless communication circuit 14 performs wireless communication with other communication terminals such as the repeater 20. The wireless communication circuit 14 operates under the control of the CPU 11, converts various signals into wireless signals by processing such as encoding and modulation, and transmits the signals via an antenna. In addition, the wireless communication circuit 14 converts a signal received via the antenna into an appropriate signal by processing such as demodulation / combination. Further, the wireless communication circuit 14 measures a received signal strength indicator (RSSI) based on the received signal.

  The clock circuit 15 generates a predetermined clock and clocks the time serving as the reference for the data station 10. The upper interface unit 16 performs interface processing with the server 90. The power supply circuit 17 is connected to an external power supply (not shown) and supplies power to each element of the data station 10.

<Configuration of repeater>
FIG. 4 is a block diagram of the repeater 20. The relay machine 20 transmits the detection value of the sensor 30 to the data station 10 in response to a command from the data station 10.

  The repeater 20 includes a CPU 21, a memory 22, a storage unit 23, a wireless communication circuit 24, a timer circuit 25, a power supply circuit 26, and a battery 27.

  The storage unit 23 stores various programs and various information. The CPU 21 performs various processes by reading and executing various programs from the storage unit 23. For example, in the storage unit 23, a program for forming a network communication path, a program for relaying the detection value of the sensor 30, a tree table, a routing table, a program for creating a routing table from the tree table, and a connection The sensor connection information for specifying the sensor 30 that has been set, the detection value acquired from the sensor 30, and the like are stored.

  The wireless communication circuit 24 performs wireless communication with other communication terminals. The wireless communication circuit 24 operates under the control of the CPU 21, converts various signals into wireless signals through processing such as encoding and modulation, and transmits the signals via an antenna. The wireless communication circuit 24 converts the signal received via the antenna into an appropriate signal by processing such as demodulation and decoding. Further, the wireless communication circuit 24 measures the received signal strength based on the received signal.

  The clock circuit 25 generates a predetermined clock and clocks a time that is a reference for the repeater 20. A battery 27 is connected to the power circuit 26. The power supply circuit 26 supplies power to each element of the repeater 20.

  The repeater 20 is in an active state in which various processes such as signal transmission / reception with other communication terminals can be executed, and in a sleep state in which power consumption is suppressed compared to the active state, although it cannot execute processes such as signal transmission / reception. And can be switched. When the repeater 20 changes from the active state to the sleep state, the CPU 21 sets the time to be in the active state in the timer circuit 25 and becomes inactive. In the sleep state, the timer circuit 25 continues timing. When the set time is reached, the timing circuit 25 notifies the CPU 21 of the arrival of the time, and the CPU 21 that has received this notification changes from the inactive state to the active state. In addition, the active CPU 21 permits power supply from the power supply circuit 26 to the memory 22, the storage unit 23, and the wireless communication circuit 24. Thus, the relay device 20 changes from the sleep state to the active state.

<Sensor configuration>
FIG. 5 is a block diagram of the sensor 30. The sensor 30 detects the vibration value (vibration magnitude) and temperature of the steam trap T or the motor M, and transmits the detected value to the corresponding relay device 20. The sensor 30 includes a sensor unit 40 that detects a predetermined physical quantity of an object, and a processing unit 50 that transmits a detection value of the sensor unit 40 to another communication terminal.

  The sensor unit 40 includes a vibration sensor and a temperature sensor, and detects the vibration value and temperature of the steam trap T or the motor M. The sensor unit 40 is installed so as to be in contact with a casing of the steam trap T (for example, an inflow portion into which steam and drain flow), and detects a vibration value and a temperature of the contacted portion. The vibration value detected by the sensor unit 40 is the magnitude of vibration at a predetermined frequency or the magnitude of vibration in a predetermined band. The sensor unit 40 outputs an electrical signal corresponding to the detected vibration value and temperature to the processing unit 50.

  The processing unit 50 includes a CPU 51, a memory 52, a storage unit 53, a wireless communication circuit 54, a timing circuit 55, a sensor interface unit 56, a power supply circuit 57, and a battery 58.

  The storage unit 53 stores various programs and various information. The CPU 51 performs various processes by reading and executing various programs from the storage unit 53. For example, the storage unit 53 includes a program for forming a network communication path, a program for acquiring a vibration value and a temperature from the sensor unit 40, and transmitting the vibration value and temperature to the relay device 20 as a detection value, and a connected relay device The relay connection information identifying 20 and the detected value are stored.

  The wireless communication circuit 54 performs wireless communication with other communication terminals. The wireless communication circuit 54 operates under the control of the CPU 51, converts various signals into wireless signals by processing such as encoding and modulation, and transmits the signals via an antenna. The wireless communication circuit 54 converts the signal received via the antenna into an appropriate signal by processing such as demodulation / compositing. Further, the wireless communication circuit 54 measures the received signal strength based on the received signal.

  The timer circuit 55 generates a predetermined clock and measures the time that is the reference of the sensor 30. The sensor interface unit 56 performs interface processing with the sensor unit 40. A battery 58 is connected to the power supply circuit 57. The power supply circuit 57 supplies power to each element of the sensor 30.

  Similar to the relay device 20, the sensor 30 can perform various processes such as transmission / reception of signals with other communication terminals and cannot perform processes such as transmission / reception of signals. It is configured to be able to switch between a sleep state in which is suppressed.

<Communication terminal connection>
In the wireless communication system 100, the connection destination of each communication terminal is determined, and signal propagation is performed based on the connection relationship. The wireless communication system 100 holds a tree table, a routing table, a sensor table, sensor connection information, and relay connection information as a connection relationship between the data station 10, the relay 20, and the sensor 30.

  The tree table is a table that defines the tree structure of the wireless communication system 100, and defines communication terminals that are higher by one hop of each repeater 20. The tree structure represents a communication path between the data station 10 and each repeater 20. In other words, the tree table defines the communication path between the data station 10 and each repeater 20. The wireless communication system 100 has two tree tables, a first tree table and a second tree table.

  The first tree table defines the tree structure of the data station 10 and all the repeaters 20. A communication path between the data station 10 and each relay device 20 defined by the first tree table is referred to as a “first communication path”. That is, the first communication path is set for all the repeaters 20 by the first tree table. For example, the communication path indicated by the tree structure shown in FIG. 1 is the first communication path. FIG. 6 is a first tree table and corresponds to the tree structure of FIG. In the upper column of the tree table, the target relay device 20 is described, and in the lower column, a higher-level communication terminal (data station 10 or relay device 20) to which each relay device 20 is connected is defined. . The data station 10 and all the repeaters 20 hold a common first tree table.

  The second tree table is a tree structure of the data station 10 and at least a part of the relay devices 20, and defines a tree structure different from the tree structure defined by the first tree table. Specifically, the second tree table defines a tree structure between the data station 10 and the relay device 20 that transmits the detection value of the sensor 30 having a high importance level (that is, the sensor 30 having a high importance level is connected). doing. A communication path between the data station 10 and each relay device 20 defined by the second tree table is referred to as a “second communication path”. Since the first communication path is set for all the relay devices 20, the relay device 20 for which the second communication path is set has two communication paths, the first communication path and the second communication path. become.

  For example, when the important level shown in FIG. 3 is set, the second communication path is set to the relays 20e, 20h, and 20k to which the sensors 30d, 30h, and 30n are connected, respectively. Here, it is assumed that the second communication path as shown in the tree structure of FIG. 7 is set. A second tree table corresponding to this tree structure is shown in FIG. In the second tree table, there are also repeaters 20a, 20c, 20d, 20f, and 20g. The repeaters 20a, 20c, 20d, 20f, and 20g are repeaters that form the second communication path of the repeaters 20e, 20h, and 20k by performing a relay process. The communication paths of the relay devices 20a, 20c, 20d, 20f, and 20g remain the first communication path, and the second communication path is not set. The data station 10 and the relay device 20 (in this example, the relay devices 20a, 20c, 20d, 20e, 20f, 20g, 20h, and 20k) that form the second communication path hold a common second tree table. .

  The routing table is a correspondence relationship between all communication terminals that are reachable from a certain communication terminal and the next (one hop ahead) communication terminal in a communication path from the certain communication terminal to the final transmission destination. That is, a communication terminal that is one hop lower than a certain communication terminal in the communication path to the final transmission destination is defined. Each of the data station 10 and each relay 20 holds a unique routing table. The routing table is created based on the tree table. Since the wireless communication system 100 has the first tree table and the second tree table, a routing table corresponding to each of them is created. Hereinafter, the routing table created based on the first tree table is referred to as “first routing table”, and the routing table created based on the second tree table is referred to as “second routing table”.

  FIG. 9 is a first routing table of the repeater 20a. In the upper column of the routing table, the target final transmission destination is described, and in the lower column, the repeater 20 that is one hop ahead when starting from the repeater 20a is defined. The first routing table defines the next (one hop ahead) communication terminal in each communication path from the corresponding communication terminal to all final destination communication terminals that can be reached based on the first tree table. . For example, since the repeaters 20a can reach the repeaters 20b, 20c, 20d, 20e, 20f, 20g, 20h, and 20i based on the first tree table, they are on the communication path to the repeaters 20. A relay machine 20 that is one hop below the relay machine 20a is defined. Since the relay devices 20j and 20k cannot be reached from the relay device 20a, the routing table of the relay device 20a does not define the relay device 20 that is one hop ahead when the final transmission destination is the relay devices 20j and 20k. .

  FIG. 10 is a second routing table of the repeater 20a. The second routing table defines the next (one hop ahead) communication terminal in each communication path from the corresponding communication terminal to all final destination communication terminals that can be reached based on the second tree table. . Since the second routing table is used when communicating with the repeater 20 in which the second communication path is set, the second communication path is set as the final transmission destination in the second routing table. Only the relay device 20 (in this example, the relay devices 20e, 20h, and 20k). For example, since the relay device 20a can reach the relay devices 20e, 20h, and 20k based on the second tree table, the relay device is lower by one hop from the relay device 20a on the communication path to those relay devices 20. Each machine 20 is defined.

  The sensor table defines the connection relationship between the sensor 30 and the relay device 20 (that is, to which relay device 20 each sensor 30 is connected). One sensor table is created by the wireless communication system 100 and held by the data station 10. FIG. 11 is a sensor table corresponding to the wireless communication system 100 of FIG. In the upper column of the sensor table, the target sensor 30 is described, and in the lower column, the relay machine 20 to which each sensor 30 is connected is defined.

  The sensor connection information is information held by each relay device 20 and information (for example, a communication address of the sensor 30) that identifies the sensor 30 connected to each relay device 20.

  The relay connection information is information held by each of the sensors 30, and is information that identifies the relay 20 to which each sensor 30 is connected (for example, the communication address of the relay 20).

  In the wireless communication system 100, signal propagation is performed using these connection relationships.

  First, a case where a signal is transmitted from the data station 10 in the downlink direction will be described. For example, when the data station 10 requests the detection value of the sensor 30g via the first communication path, the data station 10 determines the relay device 20h to which the sensor 30g is connected based on the sensor table. Then, the data station 10 determines, based on its own first routing table, that the relay device 20 that is one hop ahead when the final transmission destination is the relay device 20h is the relay device 20a. The data station 10 transmits a signal in which the repeater 20h is set as the final transmission destination and the repeater 20a is set as the transmission destination one hop ahead. Thereafter, each repeater 20 that has received this signal changes the repeater 20 that is one hop ahead based on its own first routing table, and propagates the signal to the repeater 20h. Specifically, the relay device 20a sets the relay device 20d as a transmission destination one hop ahead and transfers the signal. The relay device 20d that has received the signal sets the relay device 20g as a transmission destination one hop ahead and transfers the signal. The relay device 20g that has received the signal sets the relay device 20h as a transmission destination one hop ahead and transfers the signal. When receiving the signal, the repeater 20h as the final transmission destination acquires a detection value from the sensor 30g based on its own sensor connection information. Then, the relay machine 20h returns the acquired detection value to the data station 10.

  Next, a case where a signal is transmitted to the data station 10 in the uplink direction will be described. For example, when the repeater 20h returns a detection value to the data station 10 via the first communication path, the repeater 20h is based on the first tree table, and the repeater 20 that is higher by one hop is the repeater 20g. Find out what is there. The relay machine 20h transmits a signal including a detection value in which the data station 10 is set as the final transmission destination and the relay machine 20g is set as the transmission destination one hop ahead. Thereafter, each repeater 20 that has received this signal changes the repeater 20 that is one hop ahead based on the first tree table and propagates the signal to the data station 10. Specifically, the repeater 20g sets the repeater 20d as a transmission destination one hop ahead and transfers the signal. The repeater 20d sets the repeater 20a as the transmission destination one hop ahead and transfers the signal. The repeater 20a sets the data station 10 as a transmission destination one hop ahead and transfers the signal. Thus, the signal is finally received by the data station 10.

  As described above, the data station 10, the relay machine 20, and the sensor 30 are connected to the communication terminals (first tree table, second tree table, first routing table, second routing table, sensor table, sensor connection information, and relay machine). A signal is transmitted based on the connection information.

<Communication schedule>
The wireless communication system 100 configured as described above communicates with each repeater 20 according to the communication schedule shown in FIG. For example, the radio communication system 100 performs a collection process that collects the detection values of the sensors 30 corresponding to each relay machine 20, that is, connected to the data station 10 as one of the driving operations.

  The communication schedule in FIG. 12 shows one cycle of processing, and the communication schedule in FIG. 12 is repeatedly executed. The communication schedule is divided into a plurality of time slots. Each repeater 20 is assigned a specific time slot (hereinafter also referred to as a “specific slot”). More specifically, each relay device 20 is assigned a specific slot (hereinafter also referred to as “first specific slot”) for communicating with the data station 10 via the first communication path. Furthermore, in addition to the first specific slot, a part of the repeaters 20 is set with a specific slot (hereinafter also referred to as “second specific slot”) that communicates with the data station 10 via the second communication path. ing. That is, the first specific slot is allocated to all the repeaters 20, and the second specific slot is allocated only to the repeaters 20 for which the second communication path is set. Each repeater 20 enters an active state in a specific slot, and basically enters a sleep state at other times.

  However, since the relay machine 20 existing on the communication path between the lower relay machine 20 and the data station 10 needs to perform relay processing when the lower relay machine 20 communicates with the data station 10, the lower relay machine Even in a specific slot for the machine 20 (hereinafter also referred to as “relay slot”), the relay process is executed.

  Further, since the sensor 30 communicates with the repeater 20 in the first specific slot of the connected repeater 20, the sensor 30 is active in the first specific slot of the repeater 20. Therefore, practically, a specific time slot is also assigned to each sensor 30. However, since a plurality of sensors 30 can be connected to the repeater 20, in such a case, the plurality of sensors 30 are assigned to the first specific slot of the repeater 20. The sensor 30 is basically in a sleep state when it is not necessary to communicate with the repeater 20.

  In the communication schedule of FIG. 12, time slots are defined in a matrix. For example, a matrix column and a tree structure hierarchy correspond to each other. For example, the data station 10 is assigned a time slot in the row L0, the relay station 20 in the first layer (that is, the number of hops is 1), the time slot in the row L1 is assigned as the first specific slot, The time slot in the column L2 is assigned as the first specific slot to the relay 20 in the second hierarchy (that is, the number of hops is 2). The same applies to the third and subsequent layers. Since the data station 10 has more processing content than the repeater 20, a plurality of time slots (all time slots in the row L0 in FIG. 12) are assigned to the data station 10 instead of one time slot. The total number of time slots is greater than the total number of data stations 10 and repeaters 20. Therefore, there is a time slot to which the repeater 20 is not assigned. A time slot that is free (not assigned as the first specific slot) is assigned as the second specific slot to the repeater 20 in which the second communication path is set. In FIG. 12, the time slot to which the code with “′” is input is the second specific slot. For example, the time slot of column L3 row N5 is allocated to the relay device 20e as the second specific slot. However, the second specific slot is assigned to a time slot after the first specific slot of the corresponding repeater 20.

  In the communication schedule, time slot processing proceeds in the column direction. For example, in a certain column (for example, column L1), processing of time slots proceeds in ascending order (that is, in the order of rows N1 to Nm) with respect to row numbers, and the time of the last row number (row Nm) of the row When the slot processing is completed, the processing proceeds in the same order from the time slot of the first row number (row N1) of the next column (for example, column L2).

<Confirm connection and time slot assignment>
In the wireless communication system 100, a connection relationship of communication terminals, that is, a communication path is established autonomously. For example, first, the data station 10 broadcasts a synchronization signal in its specific slot.

  The repeater 20 that has received the synchronization signal synchronizes and applies to the data station 10 for participation. Upon receiving the participation application, the data station 10 permits participation in the network and incorporates the relay device 20 in the tree structure. The data station 10 sets the repeater 20 in the first tree table as being connected immediately below the data station 10 and assigns a time slot to the repeater 20.

  In this way, the relay station 20 that has joined the network broadcasts a synchronization signal in its own specific slot, like the data station 10. The repeater 20 that has received this synchronization signal and has not yet joined the network synchronizes and applies to the data station 10 for participation as described above. This participation application is delivered to the data station 10 in the specific slot of the repeater 20 that has transmitted the synchronization signal. Upon receiving the participation application, the data station 10 permits participation in the network and incorporates the relay device 20 in the tree structure. The data station 10 determines that the relay device 20 that is the transmission source of the synchronization signal is determined from the time slot when the participation application is received, and that the relay device 20 that has applied for participation is connected directly below the transmission device 20 of the transmission source. Set to 1 tree table. At the same time, the data station 10 assigns a time slot (first specific slot) to the repeater 20 that has applied for participation.

  By repeating this, the first communication path between the data station 10 and the repeater 20 is established autonomously, and a first tree table and a communication schedule are created.

  The connection between the sensor 30 and the repeater 20 is established autonomously based on the received signal strength. Specifically, the sensor 30 investigates the received signal strength of the synchronization signal from the data station 10 and the repeater 20. Then, the data station 10 determines the communication terminal having the maximum received signal strength as the connection destination of the sensor 30 from the data station 10 or the repeater 20 based on the investigation result of the sensor 30, and sets it in the sensor table. . Thus, a sensor table is created.

  When the setting of the first communication path is completed for all the repeaters 20, that is, the first tree structure is established, the data station 10 sets the second communication path.

  First, each repeater 20 scans the received signal strength from other communication terminals (data station 10 and other repeater 20). Specifically, each repeater 20 enters an active state not only in its own specific slot but also in other time slots, and waits for signals from other communication terminals.

  Usually, the process performed by the repeater 20 in a specific slot includes transmission of a synchronization signal. The repeater 20 broadcasts a synchronization signal in a specific slot, and synchronizes with another repeater 20 or the sensor 30 that has received the synchronization signal. The data station 10 also broadcasts a synchronization signal in the assigned time slot and synchronizes with the other repeater 20 or sensor 30 that has received the synchronization signal.

  The repeater 20 that performs scanning waits for a synchronization signal from another communication terminal in a time slot other than its specific slot. When the repeater 20 can receive the synchronization signal, the repeater 20 measures the received signal strength.

  Each repeater 20 performs this process for one cycle of the communication schedule, thereby acquiring the availability of the synchronization signal (that is, the availability of communication) and the received signal strength in all time slots other than the specific slot. . Each repeater 20 stores data associating the slot number of the time slot, whether or not the synchronization signal can be received, and the received signal strength of the synchronization signal as scan data in the storage unit 23.

  Thereafter, the data station 10 collects scan data from all the repeaters 20. Based on the important level table and the sensor table, the data station 10 determines the repeater 20 that sets the second communication path, that is, the repeater 20 to which the sensor 30 having a high importance level is connected. In the example of FIGS. 3 and 11, the sensors 30 with high importance levels are the sensors 30d, 30h, and 30n, and the repeaters 20 to which these sensors 30d, 30h, and 30n are connected are the repeaters 20e, 20h, and 20k. is there. Then, the data station 10 determines the second communication path of the repeaters 20e, 20h, and 20k based on the collected scan data. As described above, the scan data is data for each repeater 20 that associates the slot number with the availability of the synchronization signal and the received signal strength of the synchronization signal. It is possible to know which communication terminal exists in the surrounding area and which can communicate, and how much the received signal strength is. For each of the repeaters 20e, 20h, and 20k, the data station 10 sets the repeater 20 having the strongest received signal strength as the upper-level connection destination repeater 20. The data station 10 sets the relay device 20 having the highest received signal strength as the higher-level connection destination relay device 20 for the set higher-level connection destination relay device 20. It should be noted that the lower relay device 20 than the relay device 20 for which the upper connection destination is set is excluded from the options of the upper connection destination. The data station 10 repeats the above settings until the higher-level connection destination becomes the data station 10. In this way, the second communication path from the data station 10 to the repeaters 20e, 20h, and 20k is established autonomously.

  The data station 10 creates a second tree table based on the established second communication path, and assigns a second specific slot to the repeaters 20e, 20h, and 20k to complete the communication schedule.

  However, in setting the second communication path, not only the received signal strength, but also the noise signal strength, the number of hops, the total number of relay devices 20 included in the lower level of the relay device 20 as a connection destination, and the relay device 20 as a connection destination. The remaining battery level may be taken into consideration.

  Subsequently, the data station 10 creates a first routing table based on the first tree table, and creates a second routing table based on the second tree table. The data station 10 stores the first tree table, the second tree table, the sensor table, the first routing table, the second routing table, and the communication schedule (that is, allocation of the time slot to the repeater 20) in the storage unit 13. .

  The data station 10 notifies the relay tree 20 of the first tree table, while the relay station 20 defined in the second tree table (that is, all relays related to the second communication path). Machine 20). Further, the data station 10 notifies all the repeaters 20 of the slot number of the corresponding first specific slot, and also notifies the repeater 20 to which the second communication path is set to the corresponding second specific slot. To be notified. At this time, in addition to the slot number of its own specific slot, the relay 20 that needs to perform relay processing of the lower level repeater 20 includes the specific slot of the lower level repeater 20, that is, the slot number of the relay slot. Will also be notified. Further, the data station 10 notifies each relay device 20 of the sensor connection information and each sensor 30 of the relay device connection information based on the sensor table.

  Each repeater 20 creates a first routing table based on the first tree table. The repeater 20 that has received the second tree table creates a second routing table based on the second tree table. Further, the relay machine 20 notifies the connected sensor 30 of the slot number of the first specific slot of the relay machine 20. The repeater 20 stores the slot number of the specific slot and the relay slot, the first tree table, the second tree table (if any), the first routing table, the second routing table (if any) and the sensor connection information in the storage unit 23. save.

  The sensor 30 stores the slot number of the first specific slot of the connected repeater 20 and the repeater connection information in the storage unit 53.

<System operation>
Next, the collection process of the wireless communication system 100 will be described. In the collection process, each repeater 20 communicates with the data station 10 in the corresponding specific slot, and transmits the detection value from the sensor 30 connected to the repeater 20 to the data station 10 (hereinafter, this process). Is also referred to as “reply processing”).

  First, processing of the data station 10 will be described. FIG. 13 is a flowchart showing the process of the data station 10 in the collection process.

  When the data station 10 starts the collection process, the data station 10 starts a new time slot process in step SA1. At the start of the collection process, the new time slot is the time slot in column L0, row N1.

  In step SA2, the data station 10 determines whether or not the column La including the current time slot (that is, the new time slot) is the column L0. As described above, the data station 10 is assigned to all the time slots in the column L0. That is, in step SA2, the data station 10 determines whether or not the data station 10 is assigned to the current time slot.

  If the current time slot is the time slot in the column L0, the data station 10 performs processing necessary for the data station 10 corresponding to the time slot in step SA3. Thereafter, the data station 10 returns to step SA1, and starts the processing of the next time slot when the start time of the next time slot comes. As described above, the data station 10 proceeds with the time slot processing so that the row numbers are in ascending order in the column direction. That is, while the time slot in the row L0 continues, the data station 10 repeats steps SA1 to SA3 and performs processing necessary for the data station 10.

  When the time slot moves from column L0 to column L1, in step SA4, the data station 10 receives the repeater 20 assigned to the current time slot (that is, the repeater 20 in which the current time slot is a specific slot). Yes, hereinafter referred to as “target repeater 20”). The request signal is a signal requesting the target repeater 20 to return a signal. The data station 10 communicates with the target repeater 20 via the first communication path in the first specific slot, and communicates with the target repeater 20 via the second communication path in the second specific slot.

  Thereafter, the data station 10 waits for the detection value of the sensor 30 connected to the target repeater 20 to be returned (step SA5).

  If the data station 10 does not receive the detection value of the sensor 30, it determines in step SA6 whether or not it has received a transmission completion signal from the target repeater 20. The transmission completion signal is a signal transmitted by the target repeater 20 instead of the detection value in the second specific slot, and will be described in detail later. In the first specific slot, the target repeater 20 does not transmit a transmission completion signal, so the determination in step SA6 is No.

  When the data station 10 does not receive the transmission completion signal, the data station 10 determines whether or not a predetermined first timeout condition is satisfied (step SA8). If the first timeout condition is not satisfied, the data station 10 returns to step SA4. Resend the request signal. That is, when the data station 10 does not receive both the detection value and the transmission completion signal, the data station 10 repeats the transmission of the request signal until the first timeout condition is satisfied. If the first timeout condition is satisfied, the data station 10 ends the collection of detection values in the current time slot.

  The first timeout condition is a condition for ending collection of detection values in the current time slot while waiting for a request signal. For example, a predetermined time has elapsed from the start time of the time slot or after the request signal is first transmitted. Whether or not. Alternatively, the first timeout condition may be whether or not the number of request signal transmissions has reached a predetermined number.

  On the other hand, when the data station 10 receives the detection value or the transmission completion signal, the data station 10 transmits an end signal to the target repeater 20 in step SA7. The end signal is a signal notifying that the processing in the current time slot has ended. Thereafter, the data station 10 ends the collection of detection values in the current time slot.

  The data station 10 repeats the processing from step SA1 after completing the collection of the detected values in the current time slot. That is, when the start time of the next time slot comes, the data station 10 starts processing the next time slot.

  The data station 10 sequentially collects the detection values of the sensor 30 connected to the target repeater 20 corresponding to the time slot by executing the above processing.

  Next, processing of the relay machine 20 will be described. FIG. 14 is a flowchart showing processing of the relay machine 20 in the collection processing.

  The repeater 20 is in a sleep state except for the specific slot and the relay slot. The repeater 20 enters the active state when notified of the arrival of the start time of the specific slot or the relay slot from the timer circuit 25 (step SB1).

  When the repeater 20 enters the active state, it determines whether or not the current time slot is a specific slot in step SB2.

  If the current time slot is a specific slot, the repeater 20 determines whether or not the current time slot is the first specific slot in step SB3.

  If the current time slot is the first specific slot, the repeater 20 executes the first reply process in step SB4, whereas if the current time slot is the second specific slot, the repeater 20 In step SB5, the second reply process is executed.

  On the other hand, when the current time slot is a relay slot, the relay machine 20 executes a relay process in step SB6.

  FIG. 15 is a flowchart showing the subroutine of the first reply process.

  The repeater 20 that performs the first reply process waits for a request signal from the data station 10 to be transmitted in step Sb101.

  When the relay device 20 cannot receive the request signal, the relay device 20 determines whether or not a predetermined second timeout condition is satisfied (step Sb102). If the second timeout condition is not satisfied, the relay device 20 returns to step Sb101 and continues waiting for the request signal. On the other hand, when the second timeout condition is satisfied, the relay device 20 ends the first reply process, and returns to the flowchart of FIG. 14 (specifically, step SB7). That is, the repeater 20 waits for a request signal until the second timeout condition is satisfied.

  The second timeout condition is a condition for ending the reply process while waiting for a request signal, and is, for example, whether or not a predetermined time has elapsed from the start time of the time slot.

  When receiving the request signal, the relay machine 20 acquires the detection value from the sensor 30 in step Sb103. The relay machine 20 transmits the acquired detection value toward the data station 10 in step Sb104. At this time, the relay device 20 transmits the detection value to the data station 10 via the first communication path. Specifically, the repeater 20 sets the data station 10 as the final transmission destination, sets the connection destination relay 20 that is one hop higher in the first tree table, and sets the transmission destination one hop ahead, Send the detection value.

  Thereafter, the repeater 20 waits for an end signal to be transmitted from the data station 10 (step Sb105). When the repeater 20 receives the end signal, the repeater 20 ends the first reply process and returns to the flowchart of FIG. 14 (specifically, step SB7).

  When the end signal cannot be received, the repeater 20 determines whether or not a predetermined third time-out condition is satisfied in step Sb106. If the third timeout condition is not satisfied, the relay device 20 returns to step Sb104 and retransmits the detection value. When the repeater 20 does not receive the end signal, the repeater 20 repeats transmission of the detection value until the third timeout condition is satisfied.

  The third time-out condition is a condition for ending the reply process while waiting for the end signal. For example, the third time-out condition is a time slot start time or whether a predetermined time has elapsed since the detection value was first transmitted.

  On the other hand, when the third timeout condition is satisfied, the relay device 20 sets the retransmission flag to “1” in step Sb107. The retransmission flag is a flag indicating whether or not it is necessary to retransmit the detection value in the second specific slot. The initial value of the retransmission flag is “0” indicating that retransmission is not necessary. “1” indicates that retransmission is necessary. Thereafter, the relay device 20 ends the first reply process, and returns to the flowchart of FIG. 14 (specifically, step SB7).

  As described above, when receiving the request signal from the data station 10, the relay device 20 that performs the first reply process transmits the detection value of the sensor 30 to the data station 10 through the first communication path. Thereafter, when receiving the end signal from the data station 10, the repeater 20 ends the first reply process. On the other hand, if the repeater 20 transmits the detection value to the data station 10 but cannot receive the end signal, the repeater 20 sets the retransmission flag to “1” and ends the first reply process. When the relay device 20 cannot receive the request signal from the data station 10, the relay device 20 ends the first reply process without acquiring and transmitting the detection value in the current first specific slot.

  Next, the second reply process will be described. FIG. 16 is a flowchart showing the subroutine of the second reply process.

  The repeater 20 that performs the second reply process waits for the request signal from the data station 10 to be transmitted in step Sb201. If the relay device 20 cannot receive the request signal, the relay device 20 determines whether or not the second timeout condition is satisfied (step Sb202). The processes of these steps Sb201 and Sb202 are the same as the processes of steps Sb101 and Sb102 of the first reply process.

  When receiving the request signal, the relay device 20 determines whether or not the retransmission flag is “1” in step Sb203.

  When the retransmission flag is “1”, it means that the transmission of the detection value in the first specific slot has ended abnormally. In that case, the repeater 20 retransmits the detection value in step Sb204. Specifically, the relay device 20 transmits the detection value to the data station 10 via the second communication path. The repeater 20 sets the data station 10 as the final destination, sets the one-hop higher destination relay 20 specified in the second tree table as the one-hop destination, and transmits the detection value. . The detection value at this time is a detection value acquired in the first specific slot. That is, in the second specific slot, the repeater 20 does not acquire the detection value from the sensor 30. Therefore, the sensor 30 is not in the active state in the second specific slot and remains in the sleep state.

  Thereafter, the repeater 20 waits for an end signal to be transmitted from the data station 10 (step Sb205).

  If the repeater 20 cannot receive the end signal, it determines in step Sb206 whether the third timeout condition is satisfied. The processes in steps Sb205 and sb206 are the same as steps Sb105 and sb106 in the first reply process. That is, if the relay device 20 does not receive the end signal, the repeater 20 repeats transmission of the detection value until the third timeout condition is satisfied.

  When the repeater 20 receives the end signal, or when the third timeout condition is satisfied, the repeater 20 sets the retransmission flag to “0” in step Sb207 and performs the second reply process. Then, the process returns to the flowchart of FIG. 14 (specifically, step SB7).

  On the other hand, if the retransmission flag is “0”, the relay device 20 ends the second reply process without retransmitting the detection value. Specifically, the repeater 20 transmits a transmission completion signal to the data station 10 in step Sb208. The transmission completion signal is a signal indicating that the detection value can be normally transmitted to the data station 10 in the first specific slot. The transmission completion signal is also transmitted through the second communication path.

  Thereafter, the repeater 20 waits for an end signal to be transmitted from the data station 10 in step Sb209. If the repeater 20 cannot receive the end signal, it determines in step Sb210 whether the third timeout condition is satisfied. The processes in steps Sb209 and sb210 are the same as steps Sb105 and sb106 in the first reply process. That is, if the repeater 20 does not receive the end signal, the repeater 20 repeats transmission of the transmission completion signal until the third timeout condition is satisfied.

  When the repeater 20 receives the end signal or when the third timeout condition is satisfied, as described above, the repeater 20 sets the retransmission flag to “0” in step Sb207, and 2 Ends the reply process and returns to the flowchart of FIG. 14 (specifically, step SB7).

  As described above, when the repeater 20 that performs the second reply process receives the request signal from the data station 10, if the retransmission flag is “1”, the relay 30 receives the detection value of the sensor 30 via the second communication path. Transmit to the data station 10. On the other hand, when the retransmission flag is “0”, the relay device 20 transmits a transmission completion signal to the data station 10 without transmitting the detection value.

  Next, the relay process will be described. FIG. 17 is a flowchart illustrating the processing of a relay processing subroutine.

  The relay device 20 that performs the relay processing waits for a signal to be transmitted from the data station 10 or another relay device 20 in step Sb301. When the relay device 20 cannot receive the signal, the relay device 20 determines whether or not the second timeout condition is satisfied (step Sb302). The process of step Sb302 is the same as the process of step Sb102 of the first reply process.

  When receiving the signal, the repeater 20 determines whether or not the signal is an end signal in step Sb303. If the signal is an end signal, the repeater 20 ends the relay process and returns to the flowchart of FIG. 14 (specifically, step SB7).

  If the signal is not an end signal, the repeater 20 determines whether or not the current time slot is the first specific slot for another repeater 20 in step Sb304. That is, the relay slot is a specific slot for any other relay device 20. The repeater 20 determines whether the specific slot is the first specific slot or the second specific slot.

  If the current time slot is the first specific slot, the repeater 20 relays the received signal via the first communication path in step Sb305. Specifically, when the received signal is a signal in the downlink direction, the repeater 20 refers to the first routing table and transfers the signal to the repeater 20 that is one hop lower corresponding to the final transmission destination. To do. On the other hand, if the received signal is a signal in the uplink direction, the relay device 20 refers to the first tree table and transfers the signal to the relay device 20 that is one hop higher connection destination. Thereafter, the relay device 20 returns to step Sb301 and repeats the processing from step Sb301.

  If the current time slot is not the first specific slot, that is, if it is the second specific slot, the repeater 20 relays the received signal via the second communication path in step Sb306. Specifically, when the received signal is a signal in the downlink direction, the relay device 20 refers to the second routing table and transfers the signal to the relay device 20 one hop lower level corresponding to the final transmission destination. To do. On the other hand, when the received signal is a signal in the uplink direction, the repeater 20 refers to the second tree table and transfers the signal to the repeater 20 that is a connection destination that is one hop higher. Thereafter, the relay device 20 returns to step Sb301 and repeats the processing from step Sb301.

  Eventually, when receiving the end signal, the repeater 20 ends the relay process and returns to the flowchart of FIG. 14 (specifically, step SB7).

  As shown in the flowchart of FIG. 14, when the relay device 20 finishes the first reply process, the second reply process, or the relay process, in step SB7, the clock circuit 25 calculates the start time of the next time slot that should be in the active state. Set to. Specifically, the repeater 20 sets the start time of the time slot that comes next among the assigned first specific slot, second specific slot, and relay slot in the clock circuit 25.

  Thereafter, the relay device 20 changes from the active state to the sleep state in step SB8. In this way, the repeater 20 ends the process in one time slot. Thereafter, when the start time of the time slot that should become the next active state arrives, the repeater 20 repeats the processing from step SB1.

  Next, the flow of signals during the collection process in the data station 10 and the repeater 20 will be described with reference to FIGS. 18 and 19 are sequence diagrams showing the flow of processing in a specific slot of the repeater 20k to which the sensor 30n having a high importance level is connected. FIG. 18 is a sequence diagram when the detection value can be normally transmitted in the first specific slot. FIG. 19 is a sequence diagram when the detection value cannot be normally transmitted in the first specific slot. The first specific slot of repeater 20k is time slot L2N4 in the communication schedule of FIG. The second specific slot of repeater 20k is time slot L2N6 in the communication schedule of FIG.

  In the first specific slot L2N4, communication between the data station 10 and the repeater 20k is performed via the first communication path. As shown in FIG. 1, the first communication path of the relay machine 20k is a path that passes through the relay machine 20j. In the second specific slot L2N6, communication between the data station 10 and the repeater 20k is performed via the second communication path. As illustrated in FIG. 7, the second communication path of the relay machine 20k is a path that passes through the relay machines 20a and 20d.

  As shown in FIG. 18, in the first specific slot L2N4, the data station 10 transmits a request signal to the relay device 20k to the relay device 20j (E11). The relay device 20j transmits the request signal to the relay device 20k (E12). When receiving the request signal, the relay device 20k transmits the detection values of the sensors 30m and 30n to the relay device 20j (E21). When the relay device 20j receives the detection value, the relay device 20j transmits the detection value to the data station 10 (E22).

  When receiving the detection value, the data station 10 transmits an end signal to the relay device 20k to the relay device 20j (E31). The repeater 20j transmits the end signal to the repeater 20k (E32). Each of the repeaters 20j and 20k enters a sleep state when it receives an end signal. Here, since the repeater 20k has successfully transmitted the detection value to the data station 10, the retransmission flag remains “0”.

  Thereafter, in the second specific slot L2N6, the data station 10 transmits a request signal to the relay device 20k to the relay device 20a (E41). The repeater 20a transmits the request signal to the repeater 20d (E42). The repeater 20d transmits the request signal to the repeater 20k (E43). Since the retransmission flag is “0”, the relay device 20k transmits a transmission completion signal to the relay device 20d as a response to the request signal (E51). When receiving the transmission completion signal, the relay device 20d transmits the transmission completion signal to the relay device 20a (E52). When receiving the transmission completion signal, the relay device 20a transmits the transmission completion signal to the data station 10 (E53).

  When receiving the transmission completion signal, the data station 10 transmits an end signal to the relay device 20k to the relay device 20a (E61). The repeater 20a transmits the end signal to the repeater 20d (E62). The repeater 20d transmits the end signal to the repeater 20k (E63). Each of the repeaters 20a, 20d, and 20k enters a sleep state when it receives an end signal.

  As described above, when the data station 10 can normally acquire the detection value in the first specific slot, the repeater 20k does not transmit the detection value in the second specific slot.

  However, as shown in FIG. 19, there are cases where the data station 10 cannot normally acquire the detection value in the first specific slot.

  Specifically, in the first specific slot L2N4, the data station 10 transmits a request signal to the relay device 20k to the relay device 20j (E11). The relay device 20j transmits the request signal to the relay device 20k (E12). When receiving the request signal, the relay device 20k transmits the detection values of the sensors 30m and 30n to the relay device 20j (E21). However, if a communication abnormality occurs between the relay machine 20k and the relay machine 20j, the detected value does not reach the relay machine 20j. Naturally, the data station 10 cannot acquire the detection value, and therefore does not transmit the end signal. Since the repeater 20k cannot receive the end signal, it determines that the detected value could not be transmitted normally to the data station 10. The repeater 20 sets the retransmission flag to “1”.

  Thereafter, in the second specific slot L2N6, the data station 10 transmits a request signal to the relay device 20k to the relay device 20a (E41). The repeater 20a transmits the request signal to the repeater 20d (E42). The repeater 20d transmits the request signal to the repeater 20k (E43). Since the retransmission flag is “1”, the relay device 20k transmits the detection value of the sensor 30n to the relay device 20d as a response to the request signal (E71). When receiving the detected value, the relay device 20d transmits the detected value to the relay device 20a (E72). When receiving the detection value, the relay machine 20a transmits the detection value to the data station 10 (E73).

  When receiving the detected value, the data station 10 transmits an end signal to the relay device 20k to the relay device 20a (E61). The repeater 20a transmits the end signal to the repeater 20d (E62). The repeater 20d transmits the end signal to the repeater 20k (E63). Each of the repeaters 20a, 20d, and 20k enters a sleep state upon receiving an end signal.

  In the second specific slot, the repeater 20k transmits only the detection value of the sensor 30n having the importance level “2” in order to reduce the communication amount, but the sensor 30m having the importance level “1”. The detection value may also be transmitted.

  As described above, when the data station 10 cannot normally acquire the detection value in the first specific slot, the repeater 20k transmits the detection value in the second specific slot.

  The relay stations 20a, 20b,... To which the sensors 30a, 30b,... Having a low importance level are connected have no second specific slot, so that the data station 10 has a normal detection value in the first specific slot. If it cannot be obtained at the same time, the detected value is not retransmitted in the communication schedule at that time, and it waits until the first specific slot of the next communication schedule.

  As described above, the wireless communication system 100 includes a plurality of communication terminals connected to each other by wireless communication, and the plurality of communication terminals transmit the data station 10 (master unit) and the detection value of the sensor 30 to the data station 10. The sensor 30 includes sensors 30d, 30h, 30n having high detection importance and sensors 30a, 30b,... Having low detection importance. The data station 10 communicates with the repeaters 20a, 20b,... That transmit the detection values of the sensors 30a, 30b,. The repeaters 20e, 20h, and 20k that transmit the detection values of the sensors 30d, 30h, and 30n communicate via a first communication path and a second communication path that is different from the first communication path.

  According to this configuration, the repeaters 20e, 20h, and 20k that transmit detection values of the highly important sensors 30d, 30h, and 30n communicate with the data station 10 via the second communication path in addition to the first communication path. Therefore, even if a communication abnormality occurs in one communication path, communication can be realized through the other communication path. As a result, the arrival rate of the detection values of the sensors 30d, 30h, and 30n having high importance to the data station 10 can be increased. On the other hand, the relay devices 20a, 20b,... That transmit the detection values of the sensors 20a, 20b,... Having a low importance level are detected via another communication path when a communication abnormality occurs in the first communication path. Is not sent. Instead of setting the first communication path and the second communication path to all the repeaters 20 that transmit the detection values of the sensors 30, the repeater 20e that transmits at least the detection values of the sensors 30d, 30h, and 30n having high importance. , 20h, 20k, the communication path in the wireless communication system 100 can be used efficiently by setting the first communication path and the second communication path. Further, by determining the relay 20 for setting the first communication path and the second communication path based on the importance of the sensor 30, risk management of the object of the sensor 30, and consequently, steam in which the object is incorporated System risk management can be performed appropriately.

  In addition, when the relay devices 20e, 20h, and 20k that transmit detection values of the sensors 30d, 30h, and 30n having high importance can normally transmit the detection values to the data station 10 via the first communication path, When the detection value is not transmitted to the data station 10 via the second communication path, but the detection value is not transmitted to the data station 10 via the first communication path, the detection value is not transmitted via the second communication path. The detection value is transmitted to the data station 10.

  According to this configuration, the detection value is transmitted via the second communication path when transmission of the detection value via the first communication path is not successful. When the detection value is normally transmitted via the first communication path, it is not necessary to transmit the detection value again via the second communication path. In such a case, since the detection value is not transmitted via the second communication path, the communication load and the communication amount in the wireless communication system 100 can be reduced.

  Further, the data station 10 holds an important level (information on importance) of the sensor 30, and based on the important level, the repeater 20, which communicates via the first communication path, the first communication path, and the first communication path. 2) The relay device 20 that performs communication via the communication path is identified.

  According to this configuration, the data station 10 has its own holding of the repeater 20 that communicates via the first communication path and the repeater 20 that communicates via the first communication path and the second communication path. It can be easily determined based on the level.

  Further, the data station 10 communicates with the repeater 20 assigned to each of the plurality of time slots in accordance with a communication schedule including a plurality of time slots, and transmits detection values of the sensors 30a, 30b,. The relay units 20a, 20b,... That are assigned the first specific slot, which is a time slot for communicating with the data station 10 via the first communication path, and receive the detection values of the sensors 30d, 30h, 30n having high importance. The relay stations 20e, 20h, and 20k to be transmitted are assigned a first specific slot and a second specific slot that is a time slot for communicating with the data station 10 via the second communication path.

  According to this configuration, the data station 10 sequentially communicates with the repeater 20 assigned to the time slot according to the communication schedule. And the relay machine 20a, 20b, ... which transmits the detected value of sensor 30a, 30b, ... with low importance communicates with the data station 10 in a 1st specific slot. On the other hand, the relay devices 20e, 20h, and 20k that transmit detection values of the sensors 30d, 30h, and 30n having high importance communicate with the data station 10 in the first specific slot and the second specific slot.

  Further, the importance level is set higher as the risk increases when an abnormality occurs in the object for which the sensor 30 acquires the detection value.

  According to this configuration, it is possible to appropriately perform risk management of the object of the sensor 30, and consequently risk management of the steam system in which the object is incorporated.

<< Other Embodiments >>
As described above, the embodiment has been described as an example of the technique disclosed in the present application. However, the technology in the present disclosure is not limited to this, and can also be applied to an embodiment in which changes, replacements, additions, omissions, and the like are appropriately performed. Moreover, it is also possible to combine each component demonstrated by the said embodiment and it can also be set as a new embodiment. In addition, among the components described in the attached drawings and detailed description, not only the components essential for solving the problem, but also the components not essential for solving the problem in order to illustrate the technology. May also be included. Therefore, it should not be immediately recognized that these non-essential components are essential as those non-essential components are described in the accompanying drawings and detailed description.

  About the said embodiment, it is good also as following structures.

  For example, the wireless communication system 100 may be applied to other than the steam system. Moreover, although the sensor 30 detects the vibration value and temperature of the steam trap T or the motor M, you may detect other physical quantities (for example, electric power etc.). Furthermore, the object of the sensor 30 is not limited to the steam trap T and the motor M. For example, a rotating device (a turbine, a pump, a compressor, an expander, a fan, a blower, a refrigerator, a reducer, a generator, or the like) may be an object of the sensor 30.

  The data station 10 communicates with the repeater 20 according to the communication schedule, but is not limited to this.

  In the communication schedule, time slots may not be defined in a matrix. The time slot allocation to the relay device 20 may not be performed for each network hierarchy.

  Moreover, although the important level is set in two stages, it may be set in three or more stages. In this case, the number of time slots allocated in one communication schedule may be set so as to increase as the importance level increases. For example, one specific slot is assigned to the relay device 20 that transmits the detection value of the sensor 30 with the importance level “1”, and the relay device 20 that transmits the detection value of the sensor 30 with the importance level “2”. Two specific slots may be allocated, and three specific slots may be allocated to the repeater 20 that transmits the detection value of the sensor 30 having the importance level “3”.

  The importance level is acquired by the data station 10 from the server 90, but is not limited to this. For example, the user may input the importance level of each sensor 30 to the data station 10. Alternatively, each sensor 30 holds an important level, and the data station 10 may acquire the important level from each sensor 30. In this case, each sensor 30 may be provided with a switch for setting an important level, and the important level of each sensor 30 may be set by the user setting the switch.

  The setting method of the first communication path and the second communication path is not limited to the above-described method. The first communication path is a reception signal strength, a noise signal strength, a packet error rate (PER), the number of hops, the total number of relay devices 20 included in the lower layer of the relay device 20 as a connection destination, and a connection destination. It may be set based on the remaining battery level of the relay machine 20 or the like. Each of these elements may be weighted, and the route with the highest evaluation may be the first communication route, and the next evaluation route may be the second communication route. Alternatively, the first communication path and the second communication path are not autonomous and may be set manually by the user.

  In the second specific slot, the repeater 20 transmits the detection value of the sensor 30 acquired in the first specific slot to the data station 10, but the present invention is not limited to this. The repeater 20 may acquire a detection value from the sensor 30 in the second specific slot and transmit the detection value to the data station 10. In that case, the sensor 30 is also active in the second specific slot.

  In the second specific slot, the detection value is transmitted on condition that the detection value cannot be appropriately transmitted in the first specific slot, but the transmission condition of the detection value is not limited to this. For example, the detection value may be transmitted in the second specific slot when the detection value cannot be appropriately transmitted in the first specific slot and the detection value is not included in a predetermined range. In addition, an arbitrary condition can be set as the transmission condition.

  In the second specific slot, the data station 10 always transmits a request signal, and the target repeater 20 determines whether or not to return a detection value in response thereto. That is, the target repeater 20 determines whether or not to transmit the detection value in the second specific slot. However, it is not limited to this. For example, the data station 10 may determine whether or not the detection value is received in the first specific slot, and may transmit the request signal in the second specific slot when the detection value is not received. When the data station 10 receives the detection value in the first specific slot, the data station 10 does not transmit a request signal in the second specific slot, and the target relay 20 that is in an active state, the relay 20 that performs relay processing, and the like A signal for putting the device in the sleep state is transmitted.

  The connection destinations of the relay device 20 and the sensor 30 are defined as a tree table, a routing table, a sensor table, sensor connection information, and relay device connection information. However, the connection destination may be defined in a form different from these. For example, the wireless communication system 100 holds a routing table that defines a route in the downlink direction, but holds a routing table that defines a route in the uplink direction as a connection destination of the repeater 20 and the sensor 30. Also good. The formats of the tree table, the routing table, and the sensor table described above are merely examples, and different formats may be used.

  The above flowchart is merely an example, and the above steps may be omitted or another step may be added.

  As described above, the technology disclosed herein is useful for a wireless communication system.

100 wireless communication system 10 data station (communication terminal, base unit)
20 Repeater (communication terminal, slave unit)
30 sensors

Claims (5)

A plurality of communication terminals connected to each other by wireless communication,
The plurality of communication terminals include a parent device and a plurality of child devices that transmit detection values of sensors to the parent device,
The sensors include a sensor with high detection importance and a sensor with low detection importance,
The base unit is
While communicating with the slave which transmits the detection value of the sensor with low importance through a predetermined first communication path,
A wireless communication system that communicates with the slave unit that transmits a detection value of the sensor having a high degree of importance via a second communication path different from the first communication path and the first communication path. . The wireless communication system according to claim 1, wherein
The slave unit that transmits a detection value of the sensor having a high importance level is as follows.
When the detection value can be normally transmitted to the parent device via the first communication path, the detection value is not transmitted to the parent device via the second communication path.
A wireless communication system that transmits a detection value to the parent device via the second communication path when transmission of the detection value to the parent device via the first communication route is unsuccessful. . The wireless communication system according to claim 1 or 2,
The base unit is
Holds information about the importance of the sensor,
Distinguishing between a slave unit that communicates via the first communication path and a slave unit that communicates via the first communication path and the second communication path based on the information relating to the importance. Wireless communication system. The wireless communication system according to any one of claims 1 to 3,
The master unit communicates with the slave unit assigned to each of the plurality of time slots according to a communication schedule including a plurality of time slots,
The slave unit that transmits the detection value of the sensor with low importance is assigned a first specific slot that is a time slot for communicating with the master unit via the first communication path,
The slave unit that transmits the detection value of the sensor having the high importance is assigned with the first specific slot and a second specific slot that is a time slot for communicating with the master unit via the second communication path. A wireless communication system. The radio communication system according to any one of claims 1 to 4,
The wireless communication system, wherein the importance is set higher as the risk increases when an abnormality occurs in an object for which the sensor acquires a detection value.

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