WO2018143094A1 - Management node for wireless communication system, and wireless communication system - Google Patents

Management node for wireless communication system, and wireless communication system Download PDF

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Publication number
WO2018143094A1
WO2018143094A1 PCT/JP2018/002514 JP2018002514W WO2018143094A1 WO 2018143094 A1 WO2018143094 A1 WO 2018143094A1 JP 2018002514 W JP2018002514 W JP 2018002514W WO 2018143094 A1 WO2018143094 A1 WO 2018143094A1
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Prior art keywords
node
communication
nodes
wireless communication
management node
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PCT/JP2018/002514
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French (fr)
Japanese (ja)
Inventor
祐子 相坂
隆之 堀邉
伸充 天知
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株式会社村田製作所
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Priority to JP2018565511A priority Critical patent/JP6766892B2/en
Publication of WO2018143094A1 publication Critical patent/WO2018143094A1/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q9/00—Arrangements in telecontrol or telemetry systems for selectively calling a substation from a main station, in which substation desired apparatus is selected for applying a control signal thereto or for obtaining measured values therefrom
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W40/00—Communication routing or communication path finding
    • H04W40/02—Communication route or path selection, e.g. power-based or shortest path routing
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W40/00—Communication routing or communication path finding
    • H04W40/02—Communication route or path selection, e.g. power-based or shortest path routing
    • H04W40/22—Communication route or path selection, e.g. power-based or shortest path routing using selective relaying for reaching a BTS [Base Transceiver Station] or an access point
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W40/00—Communication routing or communication path finding
    • H04W40/24—Connectivity information management, e.g. connectivity discovery or connectivity update
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

Definitions

  • the present invention relates to a management node of a wireless communication system constituted by a plurality of communication nodes and a wireless communication system.
  • the wireless communication system of Patent Document 1 is composed of two or more nodes.
  • the wireless communication system includes a management node (coordinator) that manages the wireless communication system.
  • the management node sets a group composed of nodes that communicate directly with the relay node. Get the communication strength at each node.
  • the management node reconfigures the network by changing the function to a relay node to a node of a specific group to which a node whose communication strength acquired by the acquisition unit is below a predetermined strength among nodes of the wireless communication system belongs Output instructions.
  • an end point wireless node that operates as a sensor or an actuator is referred to as an end device
  • a wireless node that relays information is referred to as a router
  • a wireless node that aggregates information is referred to as a coordinator.
  • routers were generally set manually, but because the receivable distance depends on the environment, such as the presence or absence of obstacles, it is difficult to determine the appropriate location and number of routers. Know-how is required. Further, since the router is accompanied by a transfer operation, the power consumption increases, so it is desirable to reduce it as much as possible. In particular, when the wireless node is battery-powered, the router has a short life, and it is desirable for the management and maintenance to reduce the number of routers.
  • the present invention provides a management node that automatically configures a wireless communication system having as few routers as possible and having an optimized arrangement location and number of routers, and a wireless communication system including such a management node.
  • the purpose is to do.
  • a management node of a wireless communication system operates by switching between a first mode in which data is not relayed and a second mode in which data is relayed according to an instruction.
  • a management node of a wireless communication system composed of a plurality of communication nodes and a communication node having a wireless communication distance of up to n hops (n is a natural number) from the management node is known
  • the wireless communication distance is n
  • a communication node that can directly communicate with the largest number of communication nodes that are not included in the communication node whose wireless communication distance is known among the communication nodes that are hops is instructed to operate in the second mode.
  • the wireless communication distance is not yet known (in other words, the largest number of communication nodes that are not connected to the network).
  • a communication node that can directly communicate with the router is set in the router.
  • the router to be set is connected to the wireless communication system as a communication node having a wireless communication distance of n + 1 hops as the maximum number of communication nodes, so that it has as few routers as possible, and the location and number of routers are optimized.
  • a wireless communication system can be automatically configured.
  • the management node performs a first process of classifying a communication node capable of directly communicating with the management node as a communication node having a radio communication distance of 1 hop, and then the radio communication distance is classified.
  • the second communication node that is capable of directly communicating with the largest number of second communication nodes that have not yet been classified in the wireless communication distance is the second communication node.
  • the largest number of communication nodes are connected to the wireless communication system for each wireless communication distance.
  • An optimized wireless communication system can be configured automatically.
  • the management node transmits a beacon signal in the first process, classifies the communication node responding to the beacon signal as a communication node having a wireless communication distance of 1 hop, and in the second process, the 1
  • the first communication node is instructed to transmit a beacon signal
  • the list information of communication nodes responding to the beacon signal is obtained from each of the one or more first communication nodes, and is included in the list information and wireless
  • the first communication node having the largest number of communication nodes whose communication distances are not yet classified may be instructed to operate in the second mode.
  • the management node instructs the one first communication node to transmit a beacon signal, and then sends a response signal to the beacon signal to the one first communication node. May be instructed to transmit a beacon signal to another first communication node.
  • the management node instructs the one first communication node to transmit a beacon signal, and then sends a response signal to the beacon signal to the one first communication node. Before receiving from, the other first communication node may be instructed to transmit a beacon signal.
  • the management node may redo the process of instructing the second mode after setting the plurality of communication nodes to the first mode.
  • the routing when the routing once set does not function due to a failure of the communication node, the routing can be redone.
  • a wireless communication system includes a plurality of communication nodes that operate by switching between a first mode that does not relay data and a second mode that relays data according to an instruction, The aforementioned management node that instructs at least one of the communication nodes to operate in the second mode.
  • the management node connects the largest number of communication nodes to the wireless communication system for each wireless communication distance, thereby having as few routers as possible and optimizing the placement location and number of routers.
  • a wireless communication system can be automatically configured.
  • Each of the plurality of communication nodes is periodically activated, performs time synchronization with the management node at the time of activation, performs intermittent operation waiting for a predetermined connection waiting time, and reduces connection waiting time during normal operation.
  • A, B is the intermittent operation start interval
  • C is the connection waiting time at the time of initial setting and disconnection
  • D is the installation period
  • X is the clock accuracy.
  • a ⁇ BX and C ⁇ (B + D) X may be satisfied.
  • each connection state is set by providing an appropriate connection waiting time in the initial state (before the routing is performed during the installation work) and in the normal operation (after the installation work is completed and the routing is performed).
  • Time synchronization with the management node of the communication node can be appropriately performed. As a result, time synchronization can be achieved while intermittently operating the communication node, so that power saving of the communication node can be realized.
  • the largest number of communication nodes are connected to the wireless communication system for each wireless communication distance from the management node. Therefore, it is possible to automatically configure a wireless communication system having as few routers as possible and having optimized router placement locations and number of placements.
  • FIG. 1 is a block diagram illustrating an example of a functional configuration of a general node.
  • FIG. 2 is a block diagram illustrating an example of a functional configuration of a general coordinator.
  • FIG. 3 is a conceptual diagram illustrating an example of a wireless communication system with a mesh topology.
  • FIG. 4 is a conceptual diagram illustrating an example of a tree topology wireless communication system.
  • FIG. 5 is a schematic diagram showing an arrangement example of nodes and coordinators.
  • FIG. 6A is a diagram illustrating an example of a routing result by flooding.
  • FIG. 6B is a diagram illustrating an example of a manual routing result.
  • FIG. 7 is a flowchart illustrating an example of the routing process according to the first embodiment.
  • FIG. 1 is a block diagram illustrating an example of a functional configuration of a general node.
  • FIG. 2 is a block diagram illustrating an example of a functional configuration of a general coordinator.
  • FIG. 3 is a conceptual diagram illustrating an example
  • FIG. 8A is a sequence chart illustrating a specific example of the routing process according to the first embodiment.
  • FIG. 8B is a sequence chart illustrating a specific example of the routing process according to the first embodiment.
  • FIG. 8C is a sequence chart illustrating a specific example of the routing process according to the first embodiment.
  • FIG. 9A is a schematic diagram illustrating a progress status of the routing process according to the first embodiment.
  • FIG. 9B is a schematic diagram illustrating a progress status of the routing process according to the first embodiment.
  • FIG. 9C is a schematic diagram illustrating a progress status of the routing process according to the first embodiment.
  • FIG. 9D is a schematic diagram illustrating a progress status of the routing process according to the first embodiment.
  • FIG. 9A is a schematic diagram illustrating a progress status of the routing process according to the first embodiment.
  • FIG. 9B is a schematic diagram illustrating a progress status of the routing process according to the first embodiment.
  • FIG. 9C is a schematic diagram illustrating
  • FIG. 9E is a schematic diagram illustrating a progress status of the routing process according to the first embodiment.
  • FIG. 9F is a schematic diagram illustrating a progress status of the routing process according to the first embodiment.
  • FIG. 9G is a schematic diagram illustrating a progress status of the routing process according to the first embodiment.
  • FIG. 9H is a schematic diagram illustrating a progress status of the routing process according to the first embodiment.
  • FIG. 9I is a schematic diagram illustrating a progress status of the routing process according to the first embodiment.
  • FIG. 9J is a schematic diagram illustrating a progress status of the routing process according to the first embodiment.
  • FIG. 9K is a schematic diagram illustrating a progress status of the routing process according to the first embodiment.
  • FIG. 9L is a schematic diagram illustrating a progress status of the routing process according to the first embodiment.
  • FIG. 10 is a diagram illustrating an example of a tree network configured by the routing process according to the first embodiment.
  • FIG. 11 is a diagram illustrating an example of a mesh network configured by routing processing according to the first embodiment.
  • FIG. 12 is a diagram illustrating an example of a mesh network configured by excluding the failed node by the routing process according to the first embodiment.
  • FIG. 13 is a diagram illustrating an example of a mesh network configured to bypass an obstacle by the routing process according to the first embodiment.
  • FIG. 14A is a sequence chart illustrating a specific example of routing processing according to the second embodiment.
  • FIG. 14B is a sequence chart illustrating a specific example of the routing process according to the second embodiment.
  • FIG. 15 is a diagram illustrating an example of a mesh network in which efficiency is increased according to the second embodiment.
  • FIG. 16 is a diagram illustrating an example of a mesh network in which efficiency is improved according to the second embodiment.
  • FIG. 17 is a diagram illustrating an example of a mesh network in which efficiency is improved according to the second embodiment.
  • FIG. 18A is a diagram for explaining intermittent operation of a node according to the third embodiment.
  • FIG. 18B is a diagram for explaining an intermittent operation of a node according to the third embodiment.
  • the wireless communication system includes a management node (coordinator) and a plurality of communication nodes (also simply referred to as nodes) whose initial state is an end device (first mode in which data is not relayed).
  • the end device can operate by switching to a router (second mode in which data is relayed) in accordance with an instruction.
  • the coordinator sets the number of nodes that can be directly connected to the farthest most distant nodes in the router for each wireless communication distance represented by the number of hops from the coordinator. Automatically configure an optimized wireless communication system.
  • FIG. 1 is a block diagram showing an example of a functional configuration of a general node.
  • the node 10 includes a communication circuit 11, an antenna 16, and an I / F (interface) 17, and can operate as any of an end device and a router.
  • the node 10 is used, for example, as a communication adapter for an external device such as a sensor or an actuator to transmit / receive measurement results and control data.
  • the communication circuit 11 includes a transmission / reception unit 12, a CPU (Central Processing Unit) 13, a ROM (Read Only Memory) 14, and a RAM (Random Access Memory) 15.
  • a CPU Central Processing Unit
  • ROM Read Only Memory
  • RAM Random Access Memory
  • the transmission / reception unit 12 transmits / receives a radio signal (radio frequency electromagnetic wave) using the antenna 16 according to a radio communication standard such as ZigBee (registered trademark).
  • a communication circuit control program is written in the ROM 14 connected to the CPU 13.
  • the RAM 15 is a memory area for operating the communication circuit control program.
  • the RAM 15 may hold operation mode information that specifies whether the node 10 operates as an end device or a router.
  • the communication circuit control program causes the node 10 to operate as an end device or a router according to the operation mode information stored in the RAM 15.
  • the I / F 17 transmits / receives data to / from an external device such as a sensor or an actuator according to a wired or wireless communication standard such as USB (Universal Serial Bus).
  • an external device such as a sensor or an actuator according to a wired or wireless communication standard such as USB (Universal Serial Bus).
  • USB Universal Serial Bus
  • FIG. 2 is a block diagram showing an example of a functional configuration of a general coordinator. As shown in FIG. 2, the coordinator 20 is configured by changing the I / F 18 of the node 10 and adding a network control unit 21.
  • the coordinator 20 is used, for example, as a gateway that relays measurement results and control data of external devices between the node 10 and the Internet or a server.
  • the I / F 18 transmits / receives data to / from the Internet or a server according to a wired or wireless communication standard such as Ethernet (registered trademark).
  • the network control unit 21 is a broadband router that relays data between a wireless communication network including the coordinator 20 and the Internet or a server.
  • Such a wireless communication system is constructed as a multi-hop network having a mesh or tree topology configuration.
  • FIG. 3 is a conceptual diagram illustrating an example of a wireless communication system with a mesh topology.
  • FIG. 4 is a conceptual diagram showing an example of a tree topology wireless communication system.
  • the communication path is represented by a solid line connecting the two nodes 10.
  • the node 10 operating as an end device is represented by a white rectangle
  • the node 10 operating as a router is represented by a light gray rectangle
  • the coordinator 20 is represented by a dark gray rectangle.
  • Such color coding of end devices, routers, and coordinators is used as appropriate in other figures.
  • the wireless communication systems 1 and 2 in FIGS. 3 and 4 are configured in accordance with a wireless communication standard such as ZigBee (registered trademark), for example.
  • the node 10 is used as a communication adapter for sensors and actuators, for example, for transmitting and receiving sensor measurement results and actuator control data.
  • the node 10 can operate by switching between an end device that does not relay data (first mode) and a router that relays data (second mode) according to an instruction from the coordinator 20.
  • the coordinator 20 sets a communication path (solid line between the nodes 10 in FIGS. 3 and 4) in the wireless communication systems 1 and 2 and distributes a path table representing the set communication path to each node 10.
  • the node 10 operating as a router relays data according to the routing table.
  • the wireless communication systems 1 and 2 are connected to the Internet 40 or the server 30 via a coordinator 20 as a gateway, and are used as a sensor network that collects sensor measurement data and a control network that performs actuator drive control.
  • the server 30 may be arranged in the wireless communication systems 1 and 2.
  • FIG. 5 is a schematic diagram showing an arrangement example of the node 10 and the coordinator 20.
  • the individual nodes 10 are distinguished by the letters A to L.
  • a general routing process conventionally performed by the coordinator 20 will be described as a comparative example.
  • the coordinator 20 broadcasts an investigation signal.
  • the investigation signal is transferred (flooded) between the nodes 10 capable of direct communication and spreads over the entire wireless communication network.
  • the node 10 performs routing by recording the node 10 that is the transmission source of the received investigation signal as a router.
  • the node 10 transmits the sensor data to the recorded router, so that the sensor data is transferred in the reverse direction along the route of the investigation signal and reaches the coordinator 20.
  • FIG. 6A is a diagram illustrating an example of a routing result by flooding. As shown in FIG. 6A, when routing by flooding is performed, all the nodes 10 to which the investigation signal is transferred become routers, and therefore, it is easy to set routers excessively and obtain an efficient route with a small number of hops. Is difficult.
  • FIG. 6B is a diagram showing an example of a manual routing result.
  • routers are often arranged all along the route from the coordinator 20 to the node 10 with an emphasis on the stability of wireless connection.
  • complicated and difficult work is required, such as confirmation of the propagation state in the field so that the stability of the wireless connection is maintained.
  • the present inventors have conducted routing processing capable of automatically configuring a wireless communication system having as few routers as possible and having optimized router placement locations and number of placements, and We have devised a coordinator that performs such routing processing.
  • FIG. 7 is a flowchart illustrating an example of the routing process according to the embodiment.
  • the flowchart of FIG. 7 represents a process of setting, as a router, a node that can be directly connected to the largest number of nodes farther away for each wireless communication distance represented by the number of hops from the coordinator 20.
  • the routing process may be composed of a first process and a second process, for example.
  • a communication node that can directly communicate with the coordinator 20 is classified as a communication node having a wireless communication distance of 1 hop.
  • the second processing among the first communication nodes that are one or more communication nodes having the largest number of hops among the classified wireless communication distances, the largest number of second communications whose wireless communication distances are not yet classified.
  • a first communication node capable of directly communicating with the node is instructed to operate in the second mode. Further, the largest number of the second communication nodes are classified as communication nodes having a hop number larger than the hop number of the first communication node. The second process is executed until there is no communication node whose wireless communication distance is not classified.
  • an investigation beacon signal is used to determine a node that can be directly connected.
  • the wireless communication distance is referred to as a short distance, and a hop that is a unit of the wireless communication distance may be omitted.
  • FIG. 8A to 8C are sequence charts showing a specific example of the routing process of FIG. 7 corresponding to the node arrangement of FIG. 8A to 8C show the passage of time from the top to the bottom of the figure.
  • FIG. 9A to 9L are schematic views showing the progress of the routing process of FIG. 7 corresponding to the node arrangement of FIG. 9A to 9L, the reach range of the beacon signal is indicated by a thick broken line, the node whose distance is not known is indicated by a dotted circle, and the node whose distance is known is indicated by a circle of a line type different for each distance. ing. Further, the node 10 operating as an end point is indicated by a white circle, the node 10 operating as a router is indicated by a light gray circle, and the coordinator 20 is indicated by a dark gray circle.
  • a node that can directly communicate with the coordinator 20 is identified (S11 in FIG. 7), and the identified node is classified as a node having a distance of 1 (S12 in FIG. 7).
  • the processing of S11 to S12 in FIG. 7 is an example of the first processing.
  • the coordinator 20 broadcasts a beacon signal for investigation (S11 in FIG. 8A).
  • the beacon signals are received by the nodes A, B, C, and E (FIG. 9A), and the nodes A, B, C, and E transmit response signals for the beacon signals.
  • the set of response signals is an example of list information of nodes that responded to the beacon signals.
  • the response signal may simply be a confirmation that the beacon signal has been received normally. Further, even if it is determined that the beacon signal has a predetermined received signal quality (for example, the signal strength RSSI or the signal-to-noise ratio S / N is equal to or higher than a predetermined value), a response signal is transmitted. Good. Further, the response signal may include an identifier of a node that transmits the response signal, and additional information such as received signal quality may be added.
  • a predetermined received signal quality for example, the signal strength RSSI or the signal-to-noise ratio S / N is equal to or higher than a predetermined value
  • the coordinator 20 receives response signals from the nodes A, B, C, and E.
  • the coordinator 20 specifies that the coordinator 20 and the nodes A, B, C, and E can communicate directly based on the response signal.
  • the coordinator 20 classifies the nodes A, B, C, and E as nodes having a distance of 1 (S12 in FIG. 8A).
  • the classification may be that the identifiers of the nodes A, B, C, and E are associated with the distance value 1 and recorded in the RAM 15 of the coordinator 20.
  • a node having a distance of 1 is indicated by a thick solid line circle.
  • the loop counter i is initialized to 1 (S13 in FIG. 7), and loop processing is executed (S14 to S19 in FIG. 7).
  • the processing of S14 to S19 in FIG. 7 is an example of the second processing.
  • a node that can directly communicate with each of the nodes having the distance i (that is, the first communication node having the largest number of hops in the classified wireless communication distance) is identified (in FIG. 7). S14).
  • the coordinator 20 instructs each of the nodes A, B, C, and E having a distance of 1 to transmit a beacon (S14 in FIG. 8B).
  • Each of the nodes A, B, C, and E when receiving a beacon transmission instruction, broadcasts a beacon signal for investigation.
  • the beacon signal transmitted by the node A is received by the nodes B, D, and E (FIG. 9B), and the nodes B, D, and E transmit a response signal indicating that the beacon signal has been received.
  • the node A receives the response signal from the nodes B, D, and E and transfers it to the coordinator 20.
  • the coordinator 20 specifies that the node A and the nodes B, D, and E can be directly communicated based on the response signal transferred from the node A.
  • beacon signal of node B is received by nodes A, C, D, E, and F (FIG. 9C)
  • the beacon signal of node C is received by nodes B, E, and F (FIG. 9D)
  • the beacon signal of E is received by nodes A, B, C, D, F, G, H, and I (FIG. 9E).
  • Nodes B, C, and E receive response signals for their respective beacon signals and transfer them to the coordinator 20.
  • the coordinator 20 can directly communicate with the node B and the nodes A, C, D, E, and F based on the transferred response signal, and can directly communicate with the node C and the nodes B, E, and F.
  • Node E and nodes A, B, C, D, F, G, H, and I are identified as being directly communicable.
  • the number of additional connections which is the number of nodes that have not yet been classified among the nodes that can directly communicate with the node (that is, the second communication node), is counted. (S15 in FIG. 7).
  • nodes A, B, C, and E are classified as nodes having a distance of 1. Therefore, for each of the nodes A, B, C, and E, the number of nodes excluding the nodes A, B, C, and E from the nodes that responded to the beacon signal for investigation is counted as the number of additional connections (in FIG. 8B). S15). As a result, the numbers of additional connections of nodes A, B, C, and E are obtained as 1, 2, 1, and 5, respectively.
  • the second mode is instructed to the node for which the maximum number of additional connections is obtained (S17 in FIG. 7), and direct communication with the node is possible. And the node whose distance is not yet classified is classified as a node whose distance is i + 1 (S18 in FIG. 7).
  • the coordinator 20 transmits a switching instruction to the second mode to the node E for which the maximum number of additional connections 5 is counted, and the node E becomes a router (S17 in FIG. 8B). At this time, the coordinator 20 instructs the node E to connect to the nodes D, F, G, H, and I as routers. This instruction corresponds to a route table representing a communication route.
  • the coordinator 20 classifies the nodes D, F, G, H, and I as nodes having a distance of 2 (S18 in FIG. 8B).
  • the classification may be that the identifiers of the nodes D, F, G, H, and I are associated with the distance value 2 and recorded in the RAM 15 of the coordinator 20.
  • FIGS. 9F to 9L a node having a distance of 2 is indicated by a double circle.
  • any of the nodes A, B, and C may be able to directly communicate with the node Z that is not directly communicable with the node E.
  • the node node A, B, or C that can directly communicate with the node Z is also set in the router, so that the signal path to the node Z can be secured.
  • the loop counter i is incremented (S19 in FIG. 7), and the loop processing is continued.
  • the coordinator 20 instructs each of the nodes D, F, G, H, and I having a distance of 2 to transmit a beacon (S14 in FIG. 8C).
  • a beacon S14 in FIG. 8C.
  • nodes D, F, G, H, and I broadcast investigation beacon signals (FIGS. 9G to 9K), and nodes D, F, G, H, Nodes that can communicate directly with each of I are identified.
  • nodes A, B, C, and E are classified as nodes having a distance of 1
  • nodes D, F, G, H, and I are classified as nodes having a distance of 2. Therefore, for each of nodes D, F, G, H, and I, the number of nodes excluding nodes A, B, C, D, E, F, G, H, and I from the nodes that responded to the investigation beacon signal Is counted as the number of additional connections (S15 in FIG. 8C). As a result, the number of additional connections of nodes D, F, G, H, and I is obtained as 0, 0, 2, 3, 2, respectively.
  • the coordinator 20 transmits an instruction to switch to the second mode to the node H where the maximum number of additional connections 3 is counted, and the node H becomes a router (S17 in FIG. 8C). At this time, the coordinator 20 instructs the node H to connect to the nodes J, K, and L as routers. This instruction corresponds to a route table representing a communication route.
  • the coordinator 20 classifies the nodes J, K, and L as nodes having a distance of 3 (S18 in FIG. 8C).
  • the classification may be that the identifiers of the nodes J, K, and L are associated with the distance value 3 and recorded in the RAM 15 of the coordinator 20.
  • the node whose distance is 3 is indicated by a thin solid circle.
  • the routing process may be terminated at this point.
  • nodes that can communicate directly with the nodes J, K, and L are specified, the number of additional connections of the nodes J, K, and L is obtained, and the maximum number of additional connections is 0. In some cases, the routing process may be terminated.
  • the tree network shown in FIG. 10 is configured.
  • a node 10 capable of directly communicating with a large number of communication nodes is set as a router.
  • the router to be set is connected to the wireless communication system as a communication node having a wireless communication distance of n + 1 hops as the maximum number of communication nodes, so that it has as few routers as possible, and the location and number of routers are optimized.
  • a wireless communication system can be automatically configured.
  • an appropriate communication node reflecting the propagation situation at the site is set as a router. Therefore, for example, significant automation and labor saving are achieved as compared with the operation of setting the router while manually measuring the propagation state.
  • a response signal to the beacon signal is received from the one node and then another node is instructed to transmit a beacon signal.
  • the response signal is less likely to be congested.
  • a connection for configuring the mesh network may be instructed to the node instructing the second mode.
  • the coordinator 20 instructs the node E to connect to the nodes A, B, and C in addition to the nodes D, F, G, H, and I. May be.
  • the coordinator 20 instructs the node H to connect to the nodes D, E, F, G, and I in addition to the nodes J, K, and L. Also good.
  • the mesh network shown in FIG. 11 can be configured.
  • the above-described routing process can automatically configure a wireless communication system in which the location and number of routers are optimized even in an environment where there is a node failure or obstacle.
  • the coordinator 20 can detect that there is no response from the node and its connection destination by detecting the loss of sensor data and the response detection to the actuator setting.
  • the coordinator 20 When the coordinator 20 detects the disconnection of the response from the node and the connection destination, the coordinator 20 sets all the nodes that can be directly connected from the node and the nodes set in the router at that time as end devices (that is, the first mode). Above, the above routing process may be performed again from the beginning. As a result, an appropriate signal path is reset by excluding a node in which the response is interrupted.
  • the disruption of the response from the node and its connection destination is an example of a condition for restarting the routing process from the beginning.
  • a mesh network excluding the node E as shown in FIG. 12 can be automatically configured.
  • FIGS. 14A and 14B are sequence charts showing a specific example of the routing process of FIG. 7 corresponding to FIG.
  • the sequence charts of FIGS. 14A and 14B are obtained by changing the sequence charts shown in FIGS. 8B and 8C, respectively, as follows. That is, after S14a in FIGS. 14A and 14B instructs one node to transmit a beacon signal, before receiving a response signal to the beacon signal from the one node, the beacon signal is transmitted to another node. It is changed to instruct to send.
  • Each node transmits a beacon signal and a response signal under arbitration using an interference prevention function such as CSMA / CA (Carrier Sense Multiple Access / Collision Avoidance).
  • CSMA / CA Carrier Sense Multiple Access / Collision Avoidance
  • the same network as in the first embodiment can be obtained even if the beacon signal is transmitted and the response signal is received in parallel at a plurality of nodes.
  • the tree network shown in FIG. 10 and the mesh network shown in FIG. 11 are configured corresponding to the arrangement example of FIG.
  • the coordinator 20 can make the network more efficient based on each connection information.
  • efficiency means that a network having a more efficient configuration is obtained by deleting a communication path in the network.
  • network efficiency improvement by the coordinator 20 will be described.
  • FIG. 15 is a diagram illustrating an example of a mesh network connection that has been improved in efficiency. According to this, for example, the route from the node A to the coordinator via the router E is not used, and when the router fails, the connection becomes impossible, that is, the route having no meaning for redundancy is removed.
  • FIG. 16 shows the efficiency of the routing of FIG. 12, which is an example of the routing when the node E fails.
  • a tree network can be constructed by reducing the number of routers and eliminating redundant routes from FIG. ing.
  • FIG. 17 shows the efficiency of the routing of FIG. 13, which is an example of routing when there is an obstacle such as a wall, and is configured by eliminating redundant routes from FIG.
  • the coordinator 20 has all the controller functions for controlling the construction of the network.
  • the present invention is not limited to this example.
  • a part or all of the controller function may be performed by a server connected directly or indirectly to the coordinator 20.
  • a cloud server via the Internet with a function for performing flexible updates such as a routing optimization function, it becomes possible to construct a system corresponding to the development of algorithms.
  • All nodes 10 may be operated intermittently synchronously for the purpose of reducing power consumption when the nodes 10 are driven by batteries. For example, in a sensor network, a case where all nodes in the network are operated only during a period of sensor data collection provided periodically. When the entire network is operated intermittently, it is necessary to synchronize all the nodes and operate simultaneously. Therefore, time synchronization between the nodes is considered.
  • the node 10 has a time mechanism such as an RTC (real time clock), and the time of all the nodes 10 is considered to be the same when the routing is completed. Further, it is considered that an error with the clock accuracy X as a limit occurs at the time of the node 10.
  • RTC real time clock
  • the time of the node 10 is shifted by a maximum of BX per cycle of the intermittent operation.
  • BX the time error that can occur in one node 10
  • the maximum deviation width between the nodes 10 It becomes 8.64 seconds.
  • communication per intermittent operation is normally completed in 10 milliseconds or less. It is assumed that the node 10 can perform time synchronization with the coordinator 20 within this communication time.
  • connection waiting time A for the node 10 to wait for connection at the start of each intermittent operation is set so as to satisfy A ⁇ BX with respect to the start cycle B and the clock accuracy X.
  • the time of the node 10 is shifted by a maximum of DX per period D.
  • D the time error that can occur in one node 10 is ⁇ 43.2 seconds
  • the maximum deviation between the nodes 10 is 86. It will be 4 seconds.
  • the connection waiting time C of the unconnected terminal is set to C based on the same concept as described above. It may be set to satisfy ⁇ A + DX.
  • a ⁇ BX may be used to satisfy C ⁇ (B + D) X. Specifically, the value of C is 95.04 seconds or more and rounded to 96 seconds or more.
  • the wireless node setting device that synchronizes the time with the coordinator 20 when the node 10 is started, and if timing synchronization is established at the time of communication connection, the connection waiting time of only A and C is provided. Communication can be established and intermittent operation including a router becomes possible.
  • time synchronization by RTC or the like is assumed.
  • synchronization is achieved by a method of resetting a counter using an internal clock. May be. That is, according to this method, a synchronized intermittent operation can be performed without a circuit for holding time.
  • the present invention can be widely used in various wireless networks such as a sensor network and an actuator control network as a management node and a wireless communication system of a wireless communication system.

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Abstract

A management node for a wireless communication system configured from a plurality of communication nodes that operate by switching between a first mode in which data is not relayed and a second mode in which data is relayed in accordance with a command, wherein when the communication nodes to which the wireless communication distance from the management node is n hops (where n is a natural number) are specified, a command to operate in the second mode is issued (S17) to a communication node, from among communication nodes for which the wireless communication distance is n hops, that is capable of communicating directly with the largest number of communication nodes not included in the specified communication nodes (S14, S15).

Description

無線通信システムの管理ノードおよび無線通信システムWireless communication system management node and wireless communication system
　本発明は、複数の通信ノードによって構成される無線通信システムの管理ノードおよび無線通信システムに関する。 The present invention relates to a management node of a wireless communication system constituted by a plurality of communication nodes and a wireless communication system.
　従来、複数の通信ノードによって構成される無線通信システムがある（例えば、特許文献１）。特許文献１の無線通信システムは、２以上のノードによって構成される。無線通信システムは、当該無線通信システムを管理する管理ノード（コーディネータ）を含む。管理ノードは、無線通信システム内の他のノードにデータの転送を行なう中継ノード（コーディネータまたはルータ）ごとに、当該中継ノードと直接通信するノードとによって構成されるグループを設定し、無線通信システムの各ノードにおける通信強度を取得する。管理ノードは、無線通信システムのノードのうち、取得手段が取得した通信強度が所定の強度を下回ったノードが属する特定のグループのノードに、中継ノードへと機能を変更してネットワークを再構築する指示を出力する。 Conventionally, there is a wireless communication system including a plurality of communication nodes (for example, Patent Document 1). The wireless communication system of Patent Document 1 is composed of two or more nodes. The wireless communication system includes a management node (coordinator) that manages the wireless communication system. For each relay node (coordinator or router) that transfers data to other nodes in the wireless communication system, the management node sets a group composed of nodes that communicate directly with the relay node. Get the communication strength at each node. The management node reconfigures the network by changing the function to a relay node to a node of a specific group to which a node whose communication strength acquired by the acquisition unit is below a predetermined strength among nodes of the wireless communication system belongs Output instructions.
　なお、本明細書では、ＺｉｇＢｅｅ（登録商標）規格での呼称に従い、センサやアクチュエータとして動作する終点無線ノードをエンドデバイス、情報を中継する無線ノードをルータ、情報を集約する無線ノードをコーディネータと称する。 In this specification, in accordance with the designation in the ZigBee (registered trademark) standard, an end point wireless node that operates as a sensor or an actuator is referred to as an end device, a wireless node that relays information is referred to as a router, and a wireless node that aggregates information is referred to as a coordinator. .
特開２０１４－８６７７６号公報JP 2014-86776 A
　特許文献１の無線通信システムに限らず一般的な無線通信システムでは、エンドデバイスから発信される無線通信について、受信可能距離には制限がある。このため、コーディネータが直接受信することができない場所に配置されたエンドデバイスから通信を受信するためには、エンドデバイスとコーディネータ間にルータを配置する必要がある。 In a general wireless communication system as well as the wireless communication system disclosed in Patent Document 1, there is a limit on the receivable distance for wireless communication transmitted from an end device. For this reason, in order to receive communication from an end device arranged in a place where the coordinator cannot receive directly, it is necessary to arrange a router between the end device and the coordinator.
　従来、ルータは手動で設定することが一般的であったところ、受信可能距離は障害物の有無等、環境に左右されるため、適切なルータの配置場所、配置数を定めることは難しく、作業者のノウハウが必要となる。また、ルータは転送動作を伴うことから消費電力が大きくなるので、できるだけ少なくすることが望まれる。特に無線ノードを電池駆動とする場合にルータは短寿命となるので、その数が少なくなる方が管理やメンテナンスの上でも望ましい。 In the past, routers were generally set manually, but because the receivable distance depends on the environment, such as the presence or absence of obstacles, it is difficult to determine the appropriate location and number of routers. Know-how is required. Further, since the router is accompanied by a transfer operation, the power consumption increases, so it is desirable to reduce it as much as possible. In particular, when the wireless node is battery-powered, the router has a short life, and it is desirable for the management and maintenance to reduce the number of routers.
　そこで、本発明は、できるだけ少ないルータを有し、ルータの配置場所、配置数が最適化された無線通信システムを自動的に構成する管理ノード、およびそのような管理ノードを含む無線通信システムを提供することを目的とする。 Therefore, the present invention provides a management node that automatically configures a wireless communication system having as few routers as possible and having an optimized arrangement location and number of routers, and a wireless communication system including such a management node. The purpose is to do.
　上記目的を達成するために、本発明の一態様に係る無線通信システムの管理ノードは、データを中継しない第１のモードとデータを中継する第２のモードとを指示に応じて切り替えて動作する複数の通信ノードで構成された無線通信システムの管理ノードであって、前記管理ノードからの無線通信距離がｎホップ（ｎは自然数）までの通信ノードが判明しているとき、無線通信距離がｎホップである通信ノードのうち、無線通信距離が判明している前記通信ノードに含まれない最多数の通信ノードと直接通信可能な通信ノードに対し、前記第２のモードで動作するよう指示する。 In order to achieve the above object, a management node of a wireless communication system according to an aspect of the present invention operates by switching between a first mode in which data is not relayed and a second mode in which data is relayed according to an instruction. When a management node of a wireless communication system composed of a plurality of communication nodes and a communication node having a wireless communication distance of up to n hops (n is a natural number) from the management node is known, the wireless communication distance is n A communication node that can directly communicate with the largest number of communication nodes that are not included in the communication node whose wireless communication distance is known among the communication nodes that are hops is instructed to operate in the second mode.
　この構成によれば、コーディネータからｎホップまでの無線通信距離にある通信ノードが判明しているとき、まだ無線通信距離が判明していない（言い換えれば、ネットワークに未接続の）最多数の通信ノードと直接通信可能な通信ノードがルータに設定される。設定されるルータは、最多数の通信ノードを、無線通信距離がｎ＋１ホップの通信ノードとして無線通信システムに接続するので、できるだけ少ないルータを有し、ルータの配置場所、配置数が最適化された無線通信システムを自動的に構成することが可能になる。 According to this configuration, when the communication nodes in the wireless communication distance from the coordinator to n hops are known, the wireless communication distance is not yet known (in other words, the largest number of communication nodes that are not connected to the network). A communication node that can directly communicate with the router is set in the router. The router to be set is connected to the wireless communication system as a communication node having a wireless communication distance of n + 1 hops as the maximum number of communication nodes, so that it has as few routers as possible, and the location and number of routers are optimized. A wireless communication system can be automatically configured.
　また、前記管理ノードは、前記管理ノードと直接通信可能な通信ノードを、無線通信距離が１ホップの通信ノードとして分類する第１の処理を行った後、無線通信距離が分類されている中でホップ数が最大の１以上の通信ノードである第１通信ノードのうち、無線通信距離がまだ分類されていない最多数の第２通信ノードと直接通信可能な第１通信ノードに対し、前記第２のモードで動作するよう指示し、前記最多数の前記第２通信ノードを、無線通信距離が前記第１通信ノードのホップ数より大きいホップ数の通信ノードとして分類する第２の処理を、無線通信距離が分類されていない通信ノードがなくなるまで、実行してもよい。 In addition, the management node performs a first process of classifying a communication node capable of directly communicating with the management node as a communication node having a radio communication distance of 1 hop, and then the radio communication distance is classified. Of the first communication nodes that are one or more communication nodes having the maximum number of hops, the second communication node that is capable of directly communicating with the largest number of second communication nodes that have not yet been classified in the wireless communication distance is the second communication node. A second process of classifying the largest number of the second communication nodes as a communication node having a hop number greater than the hop number of the first communication node. It may be executed until there are no communication nodes whose distances are not classified.
　この構成によれば、前述の処理を繰り返すことによって、無線通信距離ごとに最多数の通信ノードを無線通信システムに接続していくので、できるだけ少ないルータを有し、ルータの配置場所、配置数が最適化された無線通信システムを自動的に構成することができる。 According to this configuration, by repeating the above-described processing, the largest number of communication nodes are connected to the wireless communication system for each wireless communication distance. An optimized wireless communication system can be configured automatically.
　また、前記管理ノードは、前記第１処理において、ビーコン信号を発信し、前記ビーコン信号に応答した通信ノードを、無線通信距離が１ホップの通信ノードとして分類し、前記第２処理において、前記１以上の第１通信ノードに対しビーコン信号の発信を指示し、前記１以上の第１通信ノードの各々から前記ビーコン信号に応答した通信ノードの一覧情報を取得し、前記一覧情報に含まれかつ無線通信距離がまだ分類されていない通信ノードの個数が最多の第１通信ノードに対し、前記第２のモードで動作するよう指示してもよい。 Further, the management node transmits a beacon signal in the first process, classifies the communication node responding to the beacon signal as a communication node having a wireless communication distance of 1 hop, and in the second process, the 1 The first communication node is instructed to transmit a beacon signal, the list information of communication nodes responding to the beacon signal is obtained from each of the one or more first communication nodes, and is included in the list information and wireless The first communication node having the largest number of communication nodes whose communication distances are not yet classified may be instructed to operate in the second mode.
　この構成によれば、直接通信可能か否かをビーコン信号で特定できるので、現場での伝搬状況を反映した適切な通信ノードが、ルータとして設定される。そのため、例えば、人手で伝搬状況を測定しながらルータを設定する作業と比べて、大幅な自動化および省力化が達成される。 According to this configuration, whether or not direct communication is possible can be specified by a beacon signal, so that an appropriate communication node reflecting the propagation situation in the field is set as a router. Therefore, for example, significant automation and labor saving are achieved as compared with the operation of setting the router while manually measuring the propagation state.
　また、前記第１の通信ノードが複数あるとき、前記管理ノードは、１つの第１通信ノードに対しビーコン信号の発信を指示した後、前記ビーコン信号への応答信号を前記１つの第１通信ノードから受信してから、他の第１通信ノードに対しビーコン信号の発信を指示してもよい。 In addition, when there are a plurality of the first communication nodes, the management node instructs the one first communication node to transmit a beacon signal, and then sends a response signal to the beacon signal to the one first communication node. May be instructed to transmit a beacon signal to another first communication node.
　この構成によれば、ビーコン信号の発信および応答信号の受信を通信ノードごとに逐次に行うので、無線信号の輻輳が起こりにくくなる。 According to this configuration, since the transmission of the beacon signal and the reception of the response signal are sequentially performed for each communication node, congestion of the radio signal is less likely to occur.
　また、前記第１の通信ノードが複数あるとき、前記管理ノードは、１つの第１通信ノードに対しビーコン信号の発信を指示した後、前記ビーコン信号への応答信号を前記１つの第１通信ノードから受信する前に、他の第１通信ノードに対しビーコン信号の発信を指示してもよい。 In addition, when there are a plurality of the first communication nodes, the management node instructs the one first communication node to transmit a beacon signal, and then sends a response signal to the beacon signal to the one first communication node. Before receiving from, the other first communication node may be instructed to transmit a beacon signal.
　この構成によれば、ビーコン信号の発信および応答信号の受信を複数の通信ノードで並行して行うので、信号の送受信にかかる所要時間を短縮しやすくなる。 According to this configuration, since the transmission of the beacon signal and the reception of the response signal are performed in parallel by the plurality of communication nodes, the time required for signal transmission / reception can be easily shortened.
　また、前記管理ノードは、所定の条件が満たされると、前記複数の通信ノードを前記第１のモードにした後、前記第２のモードを指示する処理を最初からやり直してもよい。 In addition, when a predetermined condition is satisfied, the management node may redo the process of instructing the second mode after setting the plurality of communication nodes to the first mode.
　この構成によれば、一度設定したルーティングが、通信ノードの故障などにより、機能しなくなった場合に、ルーティングをやり直すことができる。 According to this configuration, when the routing once set does not function due to a failure of the communication node, the routing can be redone.
　また、本発明の一態様にかかる無線通信システムは、データを中継しない第１のモードとデータを中継する第２のモードとを指示に応じて切り替えて動作する複数の通信ノードと、前記複数の通信ノードのうちの少なくとも１つに、前記第２のモードで動作するよう指示する前述した管理ノードと、を備える。 A wireless communication system according to an aspect of the present invention includes a plurality of communication nodes that operate by switching between a first mode that does not relay data and a second mode that relays data according to an instruction, The aforementioned management node that instructs at least one of the communication nodes to operate in the second mode.
　この構成によれば、管理ノードによって、無線通信距離ごとに最多数の通信ノードが無線通信システムに接続されていくことにより、できるだけ少ないルータを有し、ルータの配置場所、配置数が最適化された無線通信システムを自動的に構成することができる。 According to this configuration, the management node connects the largest number of communication nodes to the wireless communication system for each wireless communication distance, thereby having as few routers as possible and optimizing the placement location and number of routers. A wireless communication system can be automatically configured.
　また、前記複数の通信ノードの各々は、周期的に起動し、起動時に前記管理ノードとの時刻同期を行うとともに、所定の接続待ち時間待機する間欠動作を行い、通常動作時の接続待ち時間をＡ、間欠動作の起動間隔をＢ、初期設定時および接続が切れたときの接続待ち時間をＣ、設置にかかる期間をＤ、クロック精度をＸとして、Ａ≧ＢＸ、および、Ｃ≧（Ｂ＋Ｄ）Ｘを満たしてもよい。 Each of the plurality of communication nodes is periodically activated, performs time synchronization with the management node at the time of activation, performs intermittent operation waiting for a predetermined connection waiting time, and reduces connection waiting time during normal operation. A, B is the intermittent operation start interval, C is the connection waiting time at the time of initial setting and disconnection, D is the installation period, and X is the clock accuracy. A ≧ BX and C ≧ (B + D) X may be satisfied.
　この構成によれば、初期状態（設置作業中でルーティングがなされる前）と、通常動作時（設置作業が完了しルーティングがなされた後）とで、それぞれ適した接続待ち時間を設けることにより各通信ノードの管理ノードとの時刻同期を適切に行うことができる。これにより、通信ノードを間欠動作させながら時刻同期を取ることができるので、通信ノードの省電力化を実現することができる。 According to this configuration, each connection state is set by providing an appropriate connection waiting time in the initial state (before the routing is performed during the installation work) and in the normal operation (after the installation work is completed and the routing is performed). Time synchronization with the management node of the communication node can be appropriately performed. As a result, time synchronization can be achieved while intermittently operating the communication node, so that power saving of the communication node can be realized.
　本発明の無線通信システムの管理ノードおよび無線通信システムによれば、管理ノードからの無線通信距離ごとに最多数の通信ノードを無線通信システムに接続していく。これにより、できるだけ少ないルータを有し、ルータの配置場所、配置数が最適化された無線通信システムを自動的に構成できる。 According to the management node and the wireless communication system of the wireless communication system of the present invention, the largest number of communication nodes are connected to the wireless communication system for each wireless communication distance from the management node. Thereby, it is possible to automatically configure a wireless communication system having as few routers as possible and having optimized router placement locations and number of placements.
図１は、一般的なノードの機能的な構成の一例を示すブロック図である。FIG. 1 is a block diagram illustrating an example of a functional configuration of a general node. 図２は、一般的なコーディネータの機能的な構成の一例を示すブロック図である。FIG. 2 is a block diagram illustrating an example of a functional configuration of a general coordinator. 図３は、メッシュトポロジーの無線通信システムの一例を示す概念図である。FIG. 3 is a conceptual diagram illustrating an example of a wireless communication system with a mesh topology. 図４は、ツリートポロジーの無線通信システムの一例を示す概念図である。FIG. 4 is a conceptual diagram illustrating an example of a tree topology wireless communication system. 図５は、ノードおよびコーディネータの配置例を示す模式図である。FIG. 5 is a schematic diagram showing an arrangement example of nodes and coordinators. 図６Ａは、フラッディングによるルーティング結果の一例を示す図である。FIG. 6A is a diagram illustrating an example of a routing result by flooding. 図６Ｂは、人手によるルーティング結果の一例を示す図である。FIG. 6B is a diagram illustrating an example of a manual routing result. 図７は、実施の形態１に係るルーティング処理の一例を示すフローチャートである。FIG. 7 is a flowchart illustrating an example of the routing process according to the first embodiment. 図８Ａは、実施の形態１に係るルーティング処理の一具体例を示すシーケンスチャートである。FIG. 8A is a sequence chart illustrating a specific example of the routing process according to the first embodiment. 図８Ｂは、実施の形態１に係るルーティング処理の一具体例を示すシーケンスチャートである。FIG. 8B is a sequence chart illustrating a specific example of the routing process according to the first embodiment. 図８Ｃは、実施の形態１に係るルーティング処理の一具体例を示すシーケンスチャートである。FIG. 8C is a sequence chart illustrating a specific example of the routing process according to the first embodiment. 図９Ａは、実施の形態１に係るルーティング処理の進行状況を示す模式図である。FIG. 9A is a schematic diagram illustrating a progress status of the routing process according to the first embodiment. 図９Ｂは、実施の形態１に係るルーティング処理の進行状況を示す模式図である。FIG. 9B is a schematic diagram illustrating a progress status of the routing process according to the first embodiment. 図９Ｃは、実施の形態１に係るルーティング処理の進行状況を示す模式図である。FIG. 9C is a schematic diagram illustrating a progress status of the routing process according to the first embodiment. 図９Ｄは、実施の形態１に係るルーティング処理の進行状況を示す模式図である。FIG. 9D is a schematic diagram illustrating a progress status of the routing process according to the first embodiment. 図９Ｅは、実施の形態１に係るルーティング処理の進行状況を示す模式図である。FIG. 9E is a schematic diagram illustrating a progress status of the routing process according to the first embodiment. 図９Ｆは、実施の形態１に係るルーティング処理の進行状況を示す模式図である。FIG. 9F is a schematic diagram illustrating a progress status of the routing process according to the first embodiment. 図９Ｇは、実施の形態１に係るルーティング処理の進行状況を示す模式図である。FIG. 9G is a schematic diagram illustrating a progress status of the routing process according to the first embodiment. 図９Ｈは、実施の形態１に係るルーティング処理の進行状況を示す模式図である。FIG. 9H is a schematic diagram illustrating a progress status of the routing process according to the first embodiment. 図９Ｉは、実施の形態１に係るルーティング処理の進行状況を示す模式図である。FIG. 9I is a schematic diagram illustrating a progress status of the routing process according to the first embodiment. 図９Ｊは、実施の形態１に係るルーティング処理の進行状況を示す模式図である。FIG. 9J is a schematic diagram illustrating a progress status of the routing process according to the first embodiment. 図９Ｋは、実施の形態１に係るルーティング処理の進行状況を示す模式図である。FIG. 9K is a schematic diagram illustrating a progress status of the routing process according to the first embodiment. 図９Ｌは、実施の形態１に係るルーティング処理の進行状況を示す模式図である。FIG. 9L is a schematic diagram illustrating a progress status of the routing process according to the first embodiment. 図１０は、実施の形態１に係るルーティング処理によって構成されるツリーネットワークの一例を示す図である。FIG. 10 is a diagram illustrating an example of a tree network configured by the routing process according to the first embodiment. 図１１は、実施の形態１に係るルーティング処理によって構成されるメッシュネットワークの一例を示す図である。FIG. 11 is a diagram illustrating an example of a mesh network configured by routing processing according to the first embodiment. 図１２は、実施の形態１に係るルーティング処理によって故障ノードを除外して構成されたメッシュネットワークの一例を示す図である。FIG. 12 is a diagram illustrating an example of a mesh network configured by excluding the failed node by the routing process according to the first embodiment. 図１３は、実施の形態１に係るルーティング処理によって障害物を迂回して構成されたメッシュネットワークの一例を示す図である。FIG. 13 is a diagram illustrating an example of a mesh network configured to bypass an obstacle by the routing process according to the first embodiment. 図１４Ａは、実施の形態２に係るルーティング処理の一具体例を示すシーケンスチャートである。FIG. 14A is a sequence chart illustrating a specific example of routing processing according to the second embodiment. 図１４Ｂは、実施の形態２に係るルーティング処理の一具体例を示すシーケンスチャートである。FIG. 14B is a sequence chart illustrating a specific example of the routing process according to the second embodiment. 図１５は、実施の形態２に係る効率化を実施したメッシュネットワークの一例を示す図である。FIG. 15 is a diagram illustrating an example of a mesh network in which efficiency is increased according to the second embodiment. 図１６は、実施の形態２に係る効率化を実施したメッシュネットワークの一例を示す図である。FIG. 16 is a diagram illustrating an example of a mesh network in which efficiency is improved according to the second embodiment. 図１７は、実施の形態２に係る効率化を実施したメッシュネットワークの一例を示す図である。FIG. 17 is a diagram illustrating an example of a mesh network in which efficiency is improved according to the second embodiment. 図１８Ａは、実施の形態３に係るノードの間欠動作を説明する図である。FIG. 18A is a diagram for explaining intermittent operation of a node according to the third embodiment. 図１８Ｂは、実施の形態３に係るノードの間欠動作を説明する図である。FIG. 18B is a diagram for explaining an intermittent operation of a node according to the third embodiment.
　以下、本発明の実施の形態について、図面を用いて詳細に説明する。なお、以下で説明する実施の形態は、いずれも包括的又は具体的な例を示すものである。以下の実施の形態で示される数値、形状、材料、構成要素、構成要素の配置及び接続形態、ステップ、及びステップの順序などは、一例であり、本発明を限定する主旨ではない。以下の実施の形態における構成要素のうち、独立請求項に記載されていない構成要素については、任意の構成要素として説明される。また、図面に示される構成要素の大きさ又は大きさの比は、必ずしも厳密ではない。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that each of the embodiments described below shows a comprehensive or specific example. Numerical values, shapes, materials, components, arrangement and connection forms of components, steps, order of steps, and the like shown in the following embodiments are merely examples, and are not intended to limit the present invention. Among the constituent elements in the following embodiments, constituent elements not described in the independent claims are described as optional constituent elements. In addition, the size or ratio of components shown in the drawings is not necessarily strict.
　（実施の形態１）
　実施の形態１に係る無線通信システムは、管理ノード（コーディネータ）と、初期状態がエンドデバイス（データの中継を行わない第１のモード）である複数の通信ノード（単にノードとも言う）とから構成された無線通信ネットワークである。エンドデバイスは、指示に応じて、ルータ（データの中継を行う第２のモード）に切り替わって動作することができる。 (Embodiment 1)
The wireless communication system according to Embodiment 1 includes a management node (coordinator) and a plurality of communication nodes (also simply referred to as nodes) whose initial state is an end device (first mode in which data is not relayed). Wireless communication network. The end device can operate by switching to a router (second mode in which data is relayed) in accordance with an instruction.
　コーディネータは、コーディネータからのホップ数で表される無線通信距離ごとに、より遠くにある最多数のノードと直接接続可能なノードをルータに設定していくことで、ルータの配置場所、配置数が最適化された無線通信システムを自動的に構成する。 The coordinator sets the number of nodes that can be directly connected to the farthest most distant nodes in the router for each wireless communication distance represented by the number of hops from the coordinator. Automatically configure an optimized wireless communication system.
　以下では、便宜のため、一般的な無線通信システムおよびノードの構成について説明し、その後、コーディネータによる特徴的なルーティング処理について詳細に説明する。 Hereinafter, for convenience, a general wireless communication system and a node configuration will be described, and then a characteristic routing process by the coordinator will be described in detail.
　図１は、一般的なノードの機能的な構成の一例を示すブロック図である。図１に示されるように、ノード１０は、通信回路１１、アンテナ１６、およびＩ／Ｆ（インタフェース）１７を備え、エンドデバイスおよびルータの何れとしても動作することができる。 FIG. 1 is a block diagram showing an example of a functional configuration of a general node. As shown in FIG. 1, the node 10 includes a communication circuit 11, an antenna 16, and an I / F (interface) 17, and can operate as any of an end device and a router.
　ノード１０は、例えば、センサやアクチュエータ等の外部機器の通信アダプタとして、測定結果や制御用のデータの送受信に用いられる。 The node 10 is used, for example, as a communication adapter for an external device such as a sensor or an actuator to transmit / receive measurement results and control data.
　通信回路１１は、送受信部１２、ＣＰＵ（Ｃｅｎｔｒａｌ　Ｐｒｏｃｅｓｓｉｎｇ　Ｕｎｉｔ）１３、ＲＯＭ（Ｒｅａｄ　Ｏｎｌｙ　Ｍｅｍｏｒｙ）１４、およびＲＡＭ（Ｒａｎｄｏｍ　Ａｃｃｅｓｓ　Ｍｅｍｏｒｙ）１５を有している。 The communication circuit 11 includes a transmission / reception unit 12, a CPU (Central Processing Unit) 13, a ROM (Read Only Memory) 14, and a RAM (Random Access Memory) 15.
　送受信部１２は、例えば、ＺｉｇＢｅｅ（登録商標）等の無線通信規格に従って、アンテナ１６を用いて、無線信号（無線周波数の電磁波）を送受する。 The transmission / reception unit 12 transmits / receives a radio signal (radio frequency electromagnetic wave) using the antenna 16 according to a radio communication standard such as ZigBee (registered trademark).
　ＣＰＵ１３に接続されたＲＯＭ１４には、通信回路制御プログラムが書き込まれている。ＲＡＭ１５は通信回路制御プログラムが動作するためのメモリ領域である。ＲＡＭ１５には、ノード１０がエンドデバイスおよびルータの何れとして動作するかを指定する動作モード情報が保持されていてもよい。通信回路制御プログラムは、ＲＡＭ１５に保持される動作モード情報に従って、ノード１０をエンドデバイスまたはルータとして動作させる。 A communication circuit control program is written in the ROM 14 connected to the CPU 13. The RAM 15 is a memory area for operating the communication circuit control program. The RAM 15 may hold operation mode information that specifies whether the node 10 operates as an end device or a router. The communication circuit control program causes the node 10 to operate as an end device or a router according to the operation mode information stored in the RAM 15.
　Ｉ／Ｆ１７は、例えば、ＵＳＢ（Ｕｎｉｖｅｒｓａｌ　Ｓｅｒｉａｌ　Ｂｕｓ）等の有線または無線通信規格に従って、センサやアクチュエータ等の外部機器との間で、データの送受信を行う。 The I / F 17 transmits / receives data to / from an external device such as a sensor or an actuator according to a wired or wireless communication standard such as USB (Universal Serial Bus).
　図２は、一般的なコーディネータの機能的な構成の一例を示すブロック図である。図２に示されるように、コーディネータ２０は、ノード１０のＩ／Ｆ１８を変更し、かつ網制御部２１を追加して構成される。 FIG. 2 is a block diagram showing an example of a functional configuration of a general coordinator. As shown in FIG. 2, the coordinator 20 is configured by changing the I / F 18 of the node 10 and adding a network control unit 21.
　コーディネータ２０は、例えば、外部機器の測定結果や制御用のデータを、ノード１０とインターネットやサーバとの間で中継するゲートウェイとして用いられる。 The coordinator 20 is used, for example, as a gateway that relays measurement results and control data of external devices between the node 10 and the Internet or a server.
　Ｉ／Ｆ１８は、例えば、イーサネット（登録商標）等の有線または無線通信規格に従って、インターネットまたはサーバとの間で、データを送受信する。 The I / F 18 transmits / receives data to / from the Internet or a server according to a wired or wireless communication standard such as Ethernet (registered trademark).
　網制御部２１は、コーディネータ２０を含む無線通信ネットワークと、インターネットまたはサーバとの間でデータを中継するブロードバンドルータである。 The network control unit 21 is a broadband router that relays data between a wireless communication network including the coordinator 20 and the Internet or a server.
　複数のノード１０およびコーディネータ２０を用いることにより、大出力、高感度な基地局やアクセスポイントを配置せず、小出力の通信機で大規模な無線通信システムを構築することができる。そのような無線通信システムは、メッシュやツリーのトポロジー構成のマルチホップネットワークとして構築される。 By using a plurality of nodes 10 and coordinator 20, it is possible to construct a large-scale wireless communication system with a small output communication device without arranging a high output, high sensitivity base station or access point. Such a wireless communication system is constructed as a multi-hop network having a mesh or tree topology configuration.
　図３は、メッシュトポロジーの無線通信システムの一例を示す概念図である。 FIG. 3 is a conceptual diagram illustrating an example of a wireless communication system with a mesh topology.
　図４は、ツリートポロジーの無線通信システムの一例を示す概念図である。 FIG. 4 is a conceptual diagram showing an example of a tree topology wireless communication system.
　図３、４では、通信経路を２つのノード１０を結ぶ実線で表している。また、エンドデバイスとして動作するノード１０を白色の矩形で表し、ルータとして動作するノード１０を薄い灰色の矩形で表し、コーディネータ２０を濃い灰色の矩形で表している。エンドデバイス、ルータ、およびコーディネータのこのような色分けは、他の図でも適宜用いられる。図３、４の無線通信システム１、２は、例えば、ＺｉｇＢｅｅ（登録商標）等の無線通信規格に従って構成される。 3 and 4, the communication path is represented by a solid line connecting the two nodes 10. Further, the node 10 operating as an end device is represented by a white rectangle, the node 10 operating as a router is represented by a light gray rectangle, and the coordinator 20 is represented by a dark gray rectangle. Such color coding of end devices, routers, and coordinators is used as appropriate in other figures. The wireless communication systems 1 and 2 in FIGS. 3 and 4 are configured in accordance with a wireless communication standard such as ZigBee (registered trademark), for example.
　ノード１０は、例えば、センサやアクチュエータの通信アダプタとして、センサの測定結果やアクチュエータの制御用のデータの送受信に用いられる。ノード１０は、コーディネータ２０からの指示に従って、データを中継しないエンドデバイス（第１のモード）と、データを中継するルータ（第２のモード）とを切り替わって動作することができる。 The node 10 is used as a communication adapter for sensors and actuators, for example, for transmitting and receiving sensor measurement results and actuator control data. The node 10 can operate by switching between an end device that does not relay data (first mode) and a router that relays data (second mode) according to an instruction from the coordinator 20.
　コーディネータ２０は、無線通信システム１、２における通信経路（図３、４のノード１０間の実線）を設定し、設定した通信経路を表す経路表を、各ノード１０へ配布する。ルータとして動作するノード１０は、経路表に従って、データを中継する。 The coordinator 20 sets a communication path (solid line between the nodes 10 in FIGS. 3 and 4) in the wireless communication systems 1 and 2 and distributes a path table representing the set communication path to each node 10. The node 10 operating as a router relays data according to the routing table.
　無線通信システム１、２は、ゲートウェイとしてのコーディネータ２０を介してインターネット４０またはサーバ３０に接続され、センサの測定データを収集するセンサネットワークや、アクチュエータの駆動制御を行う制御ネットワークとして用いられる。なお、サーバ３０は、無線通信システム１、２内に配置するようにしてもよい。 The wireless communication systems 1 and 2 are connected to the Internet 40 or the server 30 via a coordinator 20 as a gateway, and are used as a sensor network that collects sensor measurement data and a control network that performs actuator drive control. The server 30 may be arranged in the wireless communication systems 1 and 2.
　図５は、ノード１０およびコーディネータ２０の配置例を示す模式図である。図５では、個々のノード１０を英字Ａ～Ｌで区別している。図５を参照して、コーディネータ２０によって従来行われている一般的なルーティング処理を、比較例として説明する。 FIG. 5 is a schematic diagram showing an arrangement example of the node 10 and the coordinator 20. In FIG. 5, the individual nodes 10 are distinguished by the letters A to L. With reference to FIG. 5, a general routing process conventionally performed by the coordinator 20 will be described as a comparative example.
　例えば、センサネットワークにおいて一般的に行われる、フラッディングによるルーティングでは、コーディネータ２０は、調査用信号をブロードキャスト送信する。調査用信号は、直接通信可能なノード１０間で転送されていき（フラッディング）、無線通信ネットワーク全体に行き渡る。ノード１０は、受信した調査用信号の送信元のノード１０をルータとして記録することにより、ルーティングが行われる。ノード１０は、記録されたルータへセンサデータを送信することで、センサデータは、調査用信号の経路を逆方向に転送されてコーディネータ２０へ到達する。 For example, in routing by flooding that is generally performed in a sensor network, the coordinator 20 broadcasts an investigation signal. The investigation signal is transferred (flooded) between the nodes 10 capable of direct communication and spreads over the entire wireless communication network. The node 10 performs routing by recording the node 10 that is the transmission source of the received investigation signal as a router. The node 10 transmits the sensor data to the recorded router, so that the sensor data is transferred in the reverse direction along the route of the investigation signal and reaches the coordinator 20.
　図６Ａは、フラッディングによるルーティング結果の一例を示す図である。図６Ａに示されるように、フラッディングによるルーティングを行った場合、調査用信号を転送したノード１０が全てルータとなるため、ルータが過剰に設定され易く、ホップ数が少ない効率的な経路を得ることが難しい。 FIG. 6A is a diagram illustrating an example of a routing result by flooding. As shown in FIG. 6A, when routing by flooding is performed, all the nodes 10 to which the investigation signal is transferred become routers, and therefore, it is easy to set routers excessively and obtain an efficient route with a small number of hops. Is difficult.
　手作業によってルータ数を削減することは可能であるが、ルータとして動作させるノードの選定や配置には、現場での伝搬状況確認などのノウハウが必要となり、定型的な手順はない。 Although it is possible to reduce the number of routers manually, selection and placement of nodes to operate as routers requires know-how such as on-site propagation status confirmation, and there is no routine procedure.
　図６Ｂは、人手によるルーティング結果の一例を示す図である。図６Ｂに示されるように、人手による場合、無線接続の安定性を重視して、コーディネータ２０からノード１０へ至る経路の途中に全てルータを配置することが多い。ルータをさらに削減するためには、無線接続の安定性が維持されるように現場での伝搬状態の確認が必要になるなど、複雑で困難な作業が必要となる。 FIG. 6B is a diagram showing an example of a manual routing result. As shown in FIG. 6B, in the case of manual operation, routers are often arranged all along the route from the coordinator 20 to the node 10 with an emphasis on the stability of wireless connection. In order to further reduce the number of routers, complicated and difficult work is required, such as confirmation of the propagation state in the field so that the stability of the wireless connection is maintained.
　このような事情に鑑み、本発明者らは鋭意検討の結果、できるだけ少ないルータを有し、ルータの配置場所、配置数が最適化された無線通信システムを自動的に構成できるルーティング処理、およびそのようなルーティング処理を実行するコーディネータを考案した。 In view of such circumstances, as a result of intensive studies, the present inventors have conducted routing processing capable of automatically configuring a wireless communication system having as few routers as possible and having optimized router placement locations and number of placements, and We have devised a coordinator that performs such routing processing.
　図７は、実施の形態に係るルーティング処理の一例を示すフローチャートである。図７のフローチャートは、コーディネータ２０からのホップ数で表される無線通信距離ごとに、より遠くにある最多数のノードと直接接続可能なノードをルータとして設定していく処理を表している。 FIG. 7 is a flowchart illustrating an example of the routing process according to the embodiment. The flowchart of FIG. 7 represents a process of setting, as a router, a node that can be directly connected to the largest number of nodes farther away for each wireless communication distance represented by the number of hops from the coordinator 20.
　当該ルーティング処理は、例えば、第１の処理と第２の処理とで構成されてもよい。 The routing process may be composed of a first process and a second process, for example.
　第１の処理では、コーディネータ２０と直接通信可能な通信ノードが、無線通信距離が１ホップの通信ノードとして分類される。 In the first process, a communication node that can directly communicate with the coordinator 20 is classified as a communication node having a wireless communication distance of 1 hop.
　第２の処理では、無線通信距離が分類されている中でホップ数が最大の１以上の通信ノードである第１通信ノードのうち、無線通信距離がまだ分類されていない最多数の第２通信ノードと直接通信可能な第１通信ノードが、第２のモードで動作するよう指示される。また、前記最多数の前記第２通信ノードは、無線通信距離が前記第１通信ノードのホップ数より大きいホップ数の通信ノードとして分類される。第２の処理は、無線通信距離が分類されていない通信ノードがなくなるまで実行される。 In the second processing, among the first communication nodes that are one or more communication nodes having the largest number of hops among the classified wireless communication distances, the largest number of second communications whose wireless communication distances are not yet classified. A first communication node capable of directly communicating with the node is instructed to operate in the second mode. Further, the largest number of the second communication nodes are classified as communication nodes having a hop number larger than the hop number of the first communication node. The second process is executed until there is no communication node whose wireless communication distance is not classified.
　直接接続可能なノードの判定には、例えば、調査用のビーコン信号が用いられる。なお、以下の説明および図示では、簡潔のため、無線通信距離を短く距離と言い、無線通信距離の単位であるホップを省略することがある。 For example, an investigation beacon signal is used to determine a node that can be directly connected. In the following description and illustration, for the sake of brevity, the wireless communication distance is referred to as a short distance, and a hop that is a unit of the wireless communication distance may be omitted.
　図８Ａ～図８Ｃは、図７のルーティング処理の一具体例を、図５のノード配置に対応して示すシーケンスチャートである。図８Ａ～図８Ｃでは、図の上から下へ向かって時間の経過を表している。 8A to 8C are sequence charts showing a specific example of the routing process of FIG. 7 corresponding to the node arrangement of FIG. 8A to 8C show the passage of time from the top to the bottom of the figure.
　図９Ａ～図９Ｌは、図７のルーティング処理の進行状況を、図５のノード配置に対応して示す模式図である。図９Ａ～図９Ｌでは、ビーコン信号の到達範囲を太破線で示し、距離が判明していないノードを点線円で示し、距離が判明しているノードを、距離ごとに異なる線種の円で示している。また、エンドポイントとして動作するノード１０を白色の円で示し、ルータとして動作するノード１０を薄い灰色の円で示し、コーディネータ２０を濃い灰色の円で示している。 9A to 9L are schematic views showing the progress of the routing process of FIG. 7 corresponding to the node arrangement of FIG. 9A to 9L, the reach range of the beacon signal is indicated by a thick broken line, the node whose distance is not known is indicated by a dotted circle, and the node whose distance is known is indicated by a circle of a line type different for each distance. ing. Further, the node 10 operating as an end point is indicated by a white circle, the node 10 operating as a router is indicated by a light gray circle, and the coordinator 20 is indicated by a dark gray circle.
　図７、図８Ａ～図８Ｃ、図９Ａ～図９Ｌを参照しながら、説明を続ける。 The description will be continued with reference to FIGS. 7, 8A to 8C, and FIGS. 9A to 9L.
　まず、コーディネータ２０と直接通信可能なノードを特定し（図７のＳ１１）、特定されたノードを、距離が１のノードとして分類する（図７のＳ１２）。ここで、図７のＳ１１～Ｓ１２の処理が、第１の処理の一例である。 First, a node that can directly communicate with the coordinator 20 is identified (S11 in FIG. 7), and the identified node is classified as a node having a distance of 1 (S12 in FIG. 7). Here, the processing of S11 to S12 in FIG. 7 is an example of the first processing.
　具体例として、コーディネータ２０は、調査用のビーコン信号をブロードキャスト送信する（図８ＡのＳ１１）。ビーコン信号は、ノードＡ、Ｂ、Ｃ、Ｅで受信され（図９Ａ）、ノードＡ、Ｂ、Ｃ、Ｅは、ビーコン信号に対する返答信号を送信する。ここで、返答信号のセットがビーコン信号に応答したノードの一覧情報の一例である。 As a specific example, the coordinator 20 broadcasts a beacon signal for investigation (S11 in FIG. 8A). The beacon signals are received by the nodes A, B, C, and E (FIG. 9A), and the nodes A, B, C, and E transmit response signals for the beacon signals. Here, the set of response signals is an example of list information of nodes that responded to the beacon signals.
　返答信号は、単純に、ビーコン信号が正常に受信できたことの確認でもよい。また、ビーコン信号が所定の受信信号品質を有していること（例えば信号強度ＲＳＳＩや信号対雑音比Ｓ／Ｎが所定の値以上であることなど）を判定して返答信号を送信してもよい。また、返答信号には、返答信号を送信するノードの識別子を含み、さらに受信信号品質などの追加情報を付加してもよい。 The response signal may simply be a confirmation that the beacon signal has been received normally. Further, even if it is determined that the beacon signal has a predetermined received signal quality (for example, the signal strength RSSI or the signal-to-noise ratio S / N is equal to or higher than a predetermined value), a response signal is transmitted. Good. Further, the response signal may include an identifier of a node that transmits the response signal, and additional information such as received signal quality may be added.
　コーディネータ２０は、ノードＡ、Ｂ、Ｃ、Ｅからの返答信号を受信する。コーディネータ２０は、返答信号に基づいて、コーディネータ２０とノードＡ、Ｂ、Ｃ、Ｅとが直接通信可能であると特定する。 The coordinator 20 receives response signals from the nodes A, B, C, and E. The coordinator 20 specifies that the coordinator 20 and the nodes A, B, C, and E can communicate directly based on the response signal.
　コーディネータ２０は、ノードＡ、Ｂ、Ｃ、Ｅを、距離が１のノードとして分類する（図８ＡのＳ１２）。ここで、分類するとは、ノードＡ、Ｂ、Ｃ、Ｅの識別子を距離値１と対応付けて、コーディネータ２０のＲＡＭ１５に記録することであってもよい。図９Ａ～図９Ｌでは、距離が１のノードを太実線円で示している。 The coordinator 20 classifies the nodes A, B, C, and E as nodes having a distance of 1 (S12 in FIG. 8A). Here, the classification may be that the identifiers of the nodes A, B, C, and E are associated with the distance value 1 and recorded in the RAM 15 of the coordinator 20. In FIGS. 9A to 9L, a node having a distance of 1 is indicated by a thick solid line circle.
　次に、ループカウンタｉが１に初期化され（図７のＳ１３）、ループ処理が実行される（図７のＳ１４～Ｓ１９）。ここで、図７のＳ１４～Ｓ１９の処理が、第２の処理の一例である。 Next, the loop counter i is initialized to 1 (S13 in FIG. 7), and loop processing is executed (S14 to S19 in FIG. 7). Here, the processing of S14 to S19 in FIG. 7 is an example of the second processing.
　ループ処理では、まず、距離がｉのノード（つまり、無線通信距離が分類されている中でホップ数が最大の第１通信ノード）の各々と直接通信可能なノードが特定される（図７のＳ１４）。 In the loop processing, first, a node that can directly communicate with each of the nodes having the distance i (that is, the first communication node having the largest number of hops in the classified wireless communication distance) is identified (in FIG. 7). S14).
　ループ処理の１回目のイテレーションにおける具体例として、コーディネータ２０は、距離が１であるノードＡ、Ｂ、Ｃ、Ｅの各々に、ビーコン発信を指示する（図８ＢのＳ１４）。ノードＡ、Ｂ、Ｃ、Ｅの各々は、ビーコン発信指示を受信すると、調査用のビーコン信号をブロードキャスト送信する。 As a specific example in the first iteration of the loop processing, the coordinator 20 instructs each of the nodes A, B, C, and E having a distance of 1 to transmit a beacon (S14 in FIG. 8B). Each of the nodes A, B, C, and E, when receiving a beacon transmission instruction, broadcasts a beacon signal for investigation.
　ノードＡが発信したビーコン信号は、ノードＢ、Ｄ、Ｅで受信され（図９Ｂ）、ノードＢ、Ｄ、Ｅは、ビーコン信号が受信されたことを示す返答信号を送信する。ノードＡは、ノードＢ、Ｄ、Ｅから返答信号を受信し、コーディネータ２０へ転送する。コーディネータ２０は、ノードＡから転送された返答信号に基づいて、ノードＡとノードＢ、Ｄ、Ｅとが直接通信可能であると特定する。 The beacon signal transmitted by the node A is received by the nodes B, D, and E (FIG. 9B), and the nodes B, D, and E transmit a response signal indicating that the beacon signal has been received. The node A receives the response signal from the nodes B, D, and E and transfers it to the coordinator 20. The coordinator 20 specifies that the node A and the nodes B, D, and E can be directly communicated based on the response signal transferred from the node A.
　同様に、ノードＢのビーコン信号は、ノードＡ、Ｃ、Ｄ、Ｅ、Ｆで受信され（図９Ｃ）、ノードＣのビーコン信号は、ノードＢ、Ｅ、Ｆで受信され（図９Ｄ）、ノードＥのビーコン信号は、ノードＡ、Ｂ、Ｃ、Ｄ、Ｆ、Ｇ、Ｈ、Ｉで受信される（図９Ｅ）。ノードＢ、Ｃ、Ｅは、それぞれのビーコン信号に対する返答信号を受信し、コーディネータ２０へ転送する。 Similarly, the beacon signal of node B is received by nodes A, C, D, E, and F (FIG. 9C), and the beacon signal of node C is received by nodes B, E, and F (FIG. 9D), and the node The beacon signal of E is received by nodes A, B, C, D, F, G, H, and I (FIG. 9E). Nodes B, C, and E receive response signals for their respective beacon signals and transfer them to the coordinator 20.
　コーディネータ２０は、転送された返答信号に基づいて、ノードＢとノードＡ、Ｃ、Ｄ、Ｅ、Ｆとが直接通信可能であり、ノードＣとノードＢ、Ｅ、Ｆとが直接通信可能であり、ノードＥとノードＡ、Ｂ、Ｃ、Ｄ、Ｆ、Ｇ、Ｈ、Ｉとが直接通信可能であると特定する。 The coordinator 20 can directly communicate with the node B and the nodes A, C, D, E, and F based on the transferred response signal, and can directly communicate with the node C and the nodes B, E, and F. , Node E and nodes A, B, C, D, F, G, H, and I are identified as being directly communicable.
　次に、距離がｉのノードの各々について、前記ノードと直接通信可能なノードのうち、距離がまだ分類されていないノード（つまり、第２通信ノード）の個数である追加接続数が計数される（図７のＳ１５）。 Next, for each node having a distance i, the number of additional connections, which is the number of nodes that have not yet been classified among the nodes that can directly communicate with the node (that is, the second communication node), is counted. (S15 in FIG. 7).
　１回目のイテレーションでは、ノードＡ、Ｂ、Ｃ、Ｅが距離１のノードとして分類されている。そのため、ノードＡ、Ｂ、Ｃ、Ｅの各々について、調査用のビーコン信号に返答したノードからノードＡ、Ｂ、Ｃ、Ｅを除いたノードの個数が追加接続数として計数される（図８ＢのＳ１５）。その結果、ノードＡ、Ｂ、Ｃ、Ｅの追加接続数は、それぞれ１、２、１、５と求まる。 In the first iteration, nodes A, B, C, and E are classified as nodes having a distance of 1. Therefore, for each of the nodes A, B, C, and E, the number of nodes excluding the nodes A, B, C, and E from the nodes that responded to the beacon signal for investigation is counted as the number of additional connections (in FIG. 8B). S15). As a result, the numbers of additional connections of nodes A, B, C, and E are obtained as 1, 2, 1, and 5, respectively.
　最多の追加接続数が０であれば（図７のＳ１６でＹＥＳ）、それ以上無線通信ネットワークに接続させるノードがない（言い換えれば、距離が分類されていないノードがなくなった）ので、ルーティング処理を終了する。 If the maximum number of additional connections is 0 (YES in S16 in FIG. 7), there are no more nodes to be connected to the wireless communication network (in other words, there are no nodes whose distances are not classified). finish.
　最多の追加接続数が０でなければ（図７のＳ１６でＮＯ）、最多の追加接続数が求まったノードに対し第２のモードを指示し（図７のＳ１７）、当該ノードと直接通信可能でかつ距離がまだ分類されていないノードを、距離がｉ＋１のノードとして分類する（図７のＳ１８）。 If the maximum number of additional connections is not 0 (NO in S16 in FIG. 7), the second mode is instructed to the node for which the maximum number of additional connections is obtained (S17 in FIG. 7), and direct communication with the node is possible. And the node whose distance is not yet classified is classified as a node whose distance is i + 1 (S18 in FIG. 7).
　具体例では、コーディネータ２０は、最多の追加接続数５が計数されたノードＥへ第２のモードへの切替指示を送信し、ノードＥがルータになる（図８ＢのＳ１７）。このとき、コーディネータ２０は、ノードＥに対し、ルータとしてノードＤ、Ｆ、Ｇ、Ｈ、Ｉと接続するよう指示する。この指示は、通信経路を表す経路表に対応する。 In a specific example, the coordinator 20 transmits a switching instruction to the second mode to the node E for which the maximum number of additional connections 5 is counted, and the node E becomes a router (S17 in FIG. 8B). At this time, the coordinator 20 instructs the node E to connect to the nodes D, F, G, H, and I as routers. This instruction corresponds to a route table representing a communication route.
　コーディネータ２０は、ノードＤ、Ｆ、Ｇ、Ｈ、Ｉを、距離が２のノードとして分類する（図８ＢのＳ１８）。ここで、分類するとは、ノードＤ、Ｆ、Ｇ、Ｈ、Ｉの識別子を距離値２と対応付けて、コーディネータ２０のＲＡＭ１５に記録することであってもよい。図９Ｆ～図９Ｌでは、距離が２のノードを二重円で示している。 The coordinator 20 classifies the nodes D, F, G, H, and I as nodes having a distance of 2 (S18 in FIG. 8B). Here, the classification may be that the identifiers of the nodes D, F, G, H, and I are associated with the distance value 2 and recorded in the RAM 15 of the coordinator 20. In FIGS. 9F to 9L, a node having a distance of 2 is indicated by a double circle.
　また、図示はしていないが、ノードＡ、Ｂ、Ｃのいずれかが、ノードＥと直接通信可能でないノードＺと直接通信可能な場合があり得る。その場合、ノードＥに加えて、ノードＺと直接通信可能なノードノードＡ、Ｂ、またはＣもルータに設定することで、ノードＺへの信号経路を確保できる。 Although not shown, any of the nodes A, B, and C may be able to directly communicate with the node Z that is not directly communicable with the node E. In that case, in addition to the node E, the node node A, B, or C that can directly communicate with the node Z is also set in the router, so that the signal path to the node Z can be secured.
　ループカウンタｉがインクリメントされ（図７のＳ１９）、ループ処理が続行される。 The loop counter i is incremented (S19 in FIG. 7), and the loop processing is continued.
　ループ処理の２回目のイテレーションにおける具体例として、コーディネータ２０は、距離が２であるノードＤ、Ｆ、Ｇ、Ｈ、Ｉの各々に、ビーコン発信を指示する（図８ＣのＳ１４）。１回目のイテレーションと同様に、ノードＤ、Ｆ、Ｇ、Ｈ、Ｉは、調査用のビーコン信号をブロードキャスト送信し（図９Ｇ～図９Ｋ）、返答信号により、ノードＤ、Ｆ、Ｇ、Ｈ、Ｉの各々と直接通信可能なノードが特定される。 As a specific example in the second iteration of the loop processing, the coordinator 20 instructs each of the nodes D, F, G, H, and I having a distance of 2 to transmit a beacon (S14 in FIG. 8C). Similarly to the first iteration, nodes D, F, G, H, and I broadcast investigation beacon signals (FIGS. 9G to 9K), and nodes D, F, G, H, Nodes that can communicate directly with each of I are identified.
　２回目のイテレーションでは、ノードＡ、Ｂ、Ｃ、Ｅが距離１のノードとして分類され、ノードＤ、Ｆ、Ｇ、Ｈ、Ｉが距離２のノードとして分類されている。そのため、ノードＤ、Ｆ、Ｇ、Ｈ、Ｉの各々について、調査用のビーコン信号に返答したノードからノードＡ、Ｂ、Ｃ、Ｄ、Ｅ、Ｆ、Ｇ、Ｈ、Ｉを除いたノードの個数が追加接続数として計数される（図８ＣのＳ１５）。その結果、ノードＤ、Ｆ、Ｇ、Ｈ、Ｉの追加接続数は、それぞれ０、０、２、３、２と求まる。 In the second iteration, nodes A, B, C, and E are classified as nodes having a distance of 1, and nodes D, F, G, H, and I are classified as nodes having a distance of 2. Therefore, for each of nodes D, F, G, H, and I, the number of nodes excluding nodes A, B, C, D, E, F, G, H, and I from the nodes that responded to the investigation beacon signal Is counted as the number of additional connections (S15 in FIG. 8C). As a result, the number of additional connections of nodes D, F, G, H, and I is obtained as 0, 0, 2, 3, 2, respectively.
　コーディネータ２０は、最多の追加接続数３が計数されたノードＨへ第２のモードへの切替指示を送信し、ノードＨがルータになる（図８ＣのＳ１７）。このとき、コーディネータ２０は、ノードＨに対し、ルータとしてノードＪ、Ｋ、Ｌと接続するよう指示する。この指示は、通信経路を表す経路表に対応する。 The coordinator 20 transmits an instruction to switch to the second mode to the node H where the maximum number of additional connections 3 is counted, and the node H becomes a router (S17 in FIG. 8C). At this time, the coordinator 20 instructs the node H to connect to the nodes J, K, and L as routers. This instruction corresponds to a route table representing a communication route.
　コーディネータ２０は、ノードＪ、Ｋ、Ｌを、距離が３のノードとして分類する（図８ＣのＳ１８）。ここで、分類するとは、ノードＪ、Ｋ、Ｌの識別子を距離値３と対応付けて、コーディネータ２０のＲＡＭ１５に記録することであってもよい。図９Ｌでは、距離が３のノードを細実線円で示している。 The coordinator 20 classifies the nodes J, K, and L as nodes having a distance of 3 (S18 in FIG. 8C). Here, the classification may be that the identifiers of the nodes J, K, and L are associated with the distance value 3 and recorded in the RAM 15 of the coordinator 20. In FIG. 9L, the node whose distance is 3 is indicated by a thin solid circle.
　ノードＡ～ノードＬが無線通信ネットワークを構成するすべてのノードであるとあらかじめ分かっている場合、この時点でルーティング処理を終了してもよい。図７のフローチャートに従う場合、３回目のイテレーションにおいて、ノードＪ、Ｋ、Ｌと直接通信可能なノードを特定し、ノードＪ、Ｋ、Ｌの追加接続数を求め、最多の追加接続数が０であることによって、ルーティング処理を終了してもよい。 When it is known in advance that the nodes A to L are all nodes constituting the wireless communication network, the routing process may be terminated at this point. When the flowchart of FIG. 7 is followed, in the third iteration, nodes that can communicate directly with the nodes J, K, and L are specified, the number of additional connections of the nodes J, K, and L is obtained, and the maximum number of additional connections is 0. In some cases, the routing process may be terminated.
　以上の手順を経て、図１０に示すツリーネットワークが構成される。 Through the above procedure, the tree network shown in FIG. 10 is configured.
　以上説明したルーティング処理によれば、コーディネータ２０からｎホップまでの無線通信距離にある通信ノードが判明しているとき、まだ無線通信距離が判明していない（言い換えれば、ネットワークに未接続の）最多数の通信ノードと直接通信可能なノード１０がルータに設定される。設定されるルータは、最多数の通信ノードを、無線通信距離がｎ＋１ホップの通信ノードとして無線通信システムに接続するので、できるだけ少ないルータを有し、ルータの配置場所、配置数が最適化された無線通信システムを自動的に構成することが可能になる。 According to the routing process described above, when a communication node within the wireless communication distance from the coordinator 20 to n hops is known, the wireless communication distance is not yet known (in other words, the network is not connected to the network). A node 10 capable of directly communicating with a large number of communication nodes is set as a router. The router to be set is connected to the wireless communication system as a communication node having a wireless communication distance of n + 1 hops as the maximum number of communication nodes, so that it has as few routers as possible, and the location and number of routers are optimized. A wireless communication system can be automatically configured.
　また、直接通信可能か否かを調査用のビーコン信号で特定するので、現場での伝搬状況を反映した適切な通信ノードが、ルータとして設定される。そのため、例えば、人手で伝搬状況を測定しながらルータを設定する作業と比べて、大幅な自動化および省力化が達成される。 In addition, since whether or not direct communication is possible is specified by the beacon signal for investigation, an appropriate communication node reflecting the propagation situation at the site is set as a router. Therefore, for example, significant automation and labor saving are achieved as compared with the operation of setting the router while manually measuring the propagation state.
　また、１つのノードに対しビーコン信号の発信を指示した後、前記ビーコン信号への応答信号を前記１つのノードから受信してから、他のノードに対しビーコン信号の発信を指示するので、ビーコン信号および応答信号の輻輳が起こりにくくなる。 In addition, after instructing one node to transmit a beacon signal, a response signal to the beacon signal is received from the one node and then another node is instructed to transmit a beacon signal. In addition, the response signal is less likely to be congested.
　なお、上述のルーティング処理は、次のような変形が可能である。 It should be noted that the above-described routing process can be modified as follows.
　例えば、図７のＳ１７において、第２のモードを指示したノードに対し、メッシュネットワークを構成するための接続を指示してもよい。 For example, in S17 of FIG. 7, a connection for configuring the mesh network may be instructed to the node instructing the second mode.
　具体例では、１回目のイテレーション（図８ＢのＳ１７）において、コーディネータ２０は、ノードＥに対し、ノードＤ、Ｆ、Ｇ、Ｈ、Ｉに加えて、ノードＡ、Ｂ、Ｃと接続するよう指示してもよい。 In the specific example, in the first iteration (S17 in FIG. 8B), the coordinator 20 instructs the node E to connect to the nodes A, B, and C in addition to the nodes D, F, G, H, and I. May be.
　また、２回目のイテレーション（図８ＣのＳ１７）において、コーディネータ２０は、ノードＨに対し、ノードＪ、Ｋ、Ｌに加えて、ノードＤ、Ｅ、Ｆ、Ｇ、Ｉと接続するよう指示してもよい。 In the second iteration (S17 in FIG. 8C), the coordinator 20 instructs the node H to connect to the nodes D, E, F, G, and I in addition to the nodes J, K, and L. Also good.
　これらにより、図１１に示すメッシュネットワークを構成することができる。 Thus, the mesh network shown in FIG. 11 can be configured.
　また、上述のルーティング処理は、ノードの故障や障害物がある環境においても、ルータの配置場所、配置数が最適化された無線通信システムを自動的に構成できる。 In addition, the above-described routing process can automatically configure a wireless communication system in which the location and number of routers are optimized even in an environment where there is a node failure or obstacle.
　コーディネータ２０は、センサデータの欠損や、アクチュエータ設定への応答検知により、ノードおよびその接続先からの応答がないことを検知することができる。 The coordinator 20 can detect that there is no response from the node and its connection destination by detecting the loss of sensor data and the response detection to the actuator setting.
　コーディネータ２０は、ノードおよびその接続先からの応答の途絶を検知すると、自身から直接接続できるノードおよびそのときにルータに設定されているノードを全てエンドデバイス（つまり、第１のモード）に設定した上で、上述のルーティング処理を再度最初から行ってもよい。これにより、応答が途絶したノードを除外して適切な信号経路が再設定される。ここで、ノードおよびその接続先からの応答の途絶は、ルーティング処理を最初からやり直すための条件の一例である。 When the coordinator 20 detects the disconnection of the response from the node and the connection destination, the coordinator 20 sets all the nodes that can be directly connected from the node and the nodes set in the router at that time as end devices (that is, the first mode). Above, the above routing process may be performed again from the beginning. As a result, an appropriate signal path is reset by excluding a node in which the response is interrupted. Here, the disruption of the response from the node and its connection destination is an example of a condition for restarting the routing process from the beginning.
　例えば、図５の配置例において、ノードＥおよびその接続先からの応答がないことをコーディネータ２０が検知した場合を考える。この場合、ルーティング処理を再度最初から行うことで、図１２のような、ノードＥを除外したメッシュネットワークを自動的に構成することができる。 For example, consider the case where the coordinator 20 detects that there is no response from the node E and its connection destination in the arrangement example of FIG. In this case, by performing the routing process from the beginning again, a mesh network excluding the node E as shown in FIG. 12 can be automatically configured.
　また、図５の配置例において、ノードＤおよびノードＥとノードＧおよびノードＨとの直接通信を妨げる壁などの障害物が存在する場合を考える。この場合でも、上記のルーティング処理によれば、調査用のビーコン信号を用いて、ノードＤおよびノードＥとノードＧおよびノードＨとが直接通信可能でないことを特定できる。そのため、図１３のような、障害物５１を迂回したメッシュネットワークを自動的に構成することができる。 Further, in the arrangement example of FIG. 5, consider a case where there is an obstacle such as a wall that prevents direct communication between the node D and the node E and the node G and the node H. Even in this case, according to the routing processing described above, it is possible to specify that the node D and the node E, the node G and the node H are not directly communicable using the investigation beacon signal. Therefore, a mesh network that bypasses the obstacle 51 as shown in FIG. 13 can be automatically configured.
　（実施の形態２）
　実施の形態２では、直接通信可能なノードを特定するための調査用のビーコン信号の発信方法の変形について説明する。 (Embodiment 2)
In the second embodiment, a modification of a method for transmitting a beacon signal for investigation for specifying a node capable of direct communication will be described.
　図１４Ａ、図１４Ｂは、図７のルーティング処理の一具体例を、図５に対応して示すシーケンスチャートである。図１４Ａ、図１４Ｂのシーケンスチャートは、それぞれ図８Ｂ、図８Ｃに示されるシーケンスチャートを次のように変更してなる。すなわち、図１４Ａ、図１４ＢのＳ１４ａが、１つのノードに対しビーコン信号の発信を指示した後、前記ビーコン信号への応答信号を前記１つのノードから受信する前に、他のノードに対しビーコン信号の発信を指示するように変更される。 14A and 14B are sequence charts showing a specific example of the routing process of FIG. 7 corresponding to FIG. The sequence charts of FIGS. 14A and 14B are obtained by changing the sequence charts shown in FIGS. 8B and 8C, respectively, as follows. That is, after S14a in FIGS. 14A and 14B instructs one node to transmit a beacon signal, before receiving a response signal to the beacon signal from the one node, the beacon signal is transmitted to another node. It is changed to instruct to send.
　なお、各ノードは、例えばＣＳＭＡ／ＣＡ（Ｃａｒｒｉｅｒ　Ｓｅｎｓｅ　Ｍｕｌｔｉｐｌｅ　Ａｃｃｅｓｓ／Ｃｏｌｌｉｓｉｏｎ　Ａｖｏｉｄａｎｃｅ）などの混信防止機能を用いた調停のもとにビーコン信号および返答信号を送信するものとする。 Each node transmits a beacon signal and a response signal under arbitration using an interference prevention function such as CSMA / CA (Carrier Sense Multiple Access / Collision Avoidance).
　これにより、ビーコン信号の発信および応答信号の受信を複数のノードで並行して行うことが可能となり、ビーコン信号による直接通信可能か否かの特定に要する時間を短縮しやすくなる。 This makes it possible to transmit a beacon signal and receive a response signal in parallel at a plurality of nodes, and to easily reduce the time required for specifying whether or not direct communication using a beacon signal is possible.
　図１４Ａ、図１４Ｂのシーケンスチャートに従って、ビーコン信号の発信および応答信号の受信を複数のノードで並行して行っても、実施の形態１と同一のネットワークが得られる。例えば、図５の配置例に対応して、具体的に、図１０に示したツリーネットワークや、図１１に示したメッシュネットワークが構成される。 14A and 14B, the same network as in the first embodiment can be obtained even if the beacon signal is transmitted and the response signal is received in parallel at a plurality of nodes. For example, specifically, the tree network shown in FIG. 10 and the mesh network shown in FIG. 11 are configured corresponding to the arrangement example of FIG.
　コーディネータ２０は、各接続情報に基づいて、ネットワークを効率化することができる。ここで、効率化とは、ネットワーク中の通信経路を削除して、より効率的な構成のネットワークを得ることを言う。以下では、コーディネータ２０によるネットワークの効率化の一例について説明する。 The coordinator 20 can make the network more efficient based on each connection information. Here, efficiency means that a network having a more efficient configuration is obtained by deleting a communication path in the network. Hereinafter, an example of network efficiency improvement by the coordinator 20 will be described.
　図１５は、効率化を実施したメッシュネットワークの接続の一例を示す図である。これによると、例えばノードＡからルータＥを経由してコーディネータに至るルートを用いないなど、ルータが故障した場合に接続ができなくなる、すなわち冗長さに意味の無いルートを除去している。 FIG. 15 is a diagram illustrating an example of a mesh network connection that has been improved in efficiency. According to this, for example, the route from the node A to the coordinator via the router E is not used, and when the router fails, the connection becomes impossible, that is, the route having no meaning for redundancy is removed.
　図１６は、ノードＥが故障した場合のルーティングの一例である図１２のルーティングを効率化したものであり、図１２からルータ数を削減するとともに冗長ルートを排除することで、ツリーネットワークが構築できている。 FIG. 16 shows the efficiency of the routing of FIG. 12, which is an example of the routing when the node E fails. A tree network can be constructed by reducing the number of routers and eliminating redundant routes from FIG. ing.
　図１７は、壁などの障害物があった場合のルーティングの一例である図１３のルーティングを効率化したものであり、図１３から冗長ルートを排除することで構成されている。 FIG. 17 shows the efficiency of the routing of FIG. 13, which is an example of routing when there is an obstacle such as a wall, and is configured by eliminating redundant routes from FIG.
　なお、実施の形態１および実施の形態２では、ネットワークの構築制御を行うコントローラ機能を全てコーディネータ２０に持たせたが、この例には限られない。例えば、コントローラ機能の一部または全部をコーディネータ２０と直接または間接に接続するサーバで行ってもよい。特に、インターネットを経由したクラウドサーバにルーティングの最適化機能など、柔軟なアップデートを行いたい機能を持たせることで、アルゴリズムの発展に対応したシステムを構築することが可能になる。 In Embodiments 1 and 2, the coordinator 20 has all the controller functions for controlling the construction of the network. However, the present invention is not limited to this example. For example, a part or all of the controller function may be performed by a server connected directly or indirectly to the coordinator 20. In particular, by providing a cloud server via the Internet with a function for performing flexible updates such as a routing optimization function, it becomes possible to construct a system corresponding to the development of algorithms.
　（実施の形態３）
　実施の形態３では、ノード１０の間欠動作について説明する。 (Embodiment 3)
In the third embodiment, an intermittent operation of the node 10 will be described.
　ノード１０を電池駆動する場合の消費電力の低減を目的として、全てのノード１０を同期して間欠的に動作させることがある。例えば、センサネットワークにおいて、ネットワーク内のすべてのノードを、周期的に設けられるセンサデータの収集期間にのみ動作させる場合が該当する。ネットワーク全体を間欠的に動作させる場合、すべてのノードが同期して、同時に動作する必要があることから、ノード間の時刻同期が検討される。 All nodes 10 may be operated intermittently synchronously for the purpose of reducing power consumption when the nodes 10 are driven by batteries. For example, in a sensor network, a case where all nodes in the network are operated only during a period of sensor data collection provided periodically. When the entire network is operated intermittently, it is necessary to synchronize all the nodes and operate simultaneously. Therefore, time synchronization between the nodes is considered.
　ノード１０には、ＲＴＣ（リアルタイムクロック）等の時刻機構があり、ルーティングが完了した時点で全てのノード１０の時刻は一致していると考える。また、ノード１０の時刻には、クロック精度Ｘを限度とする誤差が生じると考える。 The node 10 has a time mechanism such as an RTC (real time clock), and the time of all the nodes 10 is considered to be the same when the routing is completed. Further, it is considered that an error with the clock accuracy X as a limit occurs at the time of the node 10.
　間欠動作の起動周期をＢとすると、ノード１０の時刻は間欠動作の１周期あたり最大でＢＸずれる。例えば、起動周期Ｂが１日（＝８６４００秒）で、クロック精度Ｘが±５０ｐｐｍの場合、１つのノード１０で生じ得る時刻の誤差は±４．３２秒、ノード１０間での最大ずれ幅は８．６４秒になる。 Assuming that the start cycle of the intermittent operation is B, the time of the node 10 is shifted by a maximum of BX per cycle of the intermittent operation. For example, when the activation cycle B is 1 day (= 86400 seconds) and the clock accuracy X is ± 50 ppm, the time error that can occur in one node 10 is ± 4.32 seconds, and the maximum deviation width between the nodes 10 is It becomes 8.64 seconds.
　間欠動作の１回あたりの通信は通常１０ミリ秒以下で完了すると考える。この通信時間内にノード１０はコーディネータ２０との時刻同期を行うことができるものとする。 Suppose that communication per intermittent operation is normally completed in 10 milliseconds or less. It is assumed that the node 10 can perform time synchronization with the coordinator 20 within this communication time.
　このとき、起動周期Ｂおよびクロック精度Ｘに対し、間欠動作の各回の起動時にノード１０が接続待ちをするための接続待ち時間Ａを、Ａ≧ＢＸを満たすように設定する。 At this time, the connection waiting time A for the node 10 to wait for connection at the start of each intermittent operation is set so as to satisfy A ≧ BX with respect to the start cycle B and the clock accuracy X.
　図１８Ａに示すように、上述の条件を満たせば、間欠動作の１周期のうちに２つのノード１０の時刻が最大限ずれたとしても、間欠動作の次の周期においてすべてのノード１０が同時に接続待ちをしている期間Ｔ（図１８Ａの灰色で示した期間、Ｔ＝Ａ－ＢＸ）が存在するので、ネットワーク全体での接続を確立することができる。 As shown in FIG. 18A, if the above conditions are satisfied, even if the time of the two nodes 10 is shifted to the maximum during one cycle of the intermittent operation, all the nodes 10 are simultaneously connected in the next cycle of the intermittent operation. Since there is a waiting period T (period shown in gray in FIG. 18A, T = A−BX), it is possible to establish a connection in the entire network.
　次に、初期設定時、および接続が切れた場合の再設定時について考える。 Next, consider the initial setting and the resetting when the connection is lost.
　初期設定（設置施工）または故障修理（メンテナンスを含む）にかかる最大の期間をＤとすると、ノード１０の時刻は、期間Ｄあたり最大でＤＸずれる。例えば、期間Ｄが１０日間（＝８６４０００秒）で、クロック精度が±５０ｐｐｍの場合、１つのノード１０で生じ得る時刻の誤差は±４３．２秒、ノード１０間での最大ずれ幅は８６．４秒になる。 Suppose that the maximum period for initial setting (installation work) or fault repair (including maintenance) is D, the time of the node 10 is shifted by a maximum of DX per period D. For example, when the period D is 10 days (= 864000 seconds) and the clock accuracy is ± 50 ppm, the time error that can occur in one node 10 is ± 43.2 seconds, and the maximum deviation between the nodes 10 is 86. It will be 4 seconds.
　図１８Ｂに示すように、同期が取れているネットワークへ、未接続のまま期間Ｄが経過した端末が接続するには、上述と同様の考え方に基づき、未接続端末の接続待ち時間Ｃを、Ｃ≧Ａ＋ＤＸを満たすように設定すればよい。Ａ≧ＢＸを用いて、Ｃ≧（Ｂ＋Ｄ）Ｘを満たすとしてもよい。具体的には、Ｃの値は９５．０４秒以上、丸めると９６秒以上になる。 As shown in FIG. 18B, in order to connect a terminal that has not been connected to the synchronized period to the synchronized network, the connection waiting time C of the unconnected terminal is set to C based on the same concept as described above. It may be set to satisfy ≧ A + DX. A ≧ BX may be used to satisfy C ≧ (B + D) X. Specifically, the value of C is 95.04 seconds or more and rounded to 96 seconds or more.
　これにより、ノード１０を起動する時にコーディネータ２０との時刻合わせを行う無線ノード設定機器を用いるとともに、通信接続時にタイミング同期を取るとすれば、上記ＡおよびＣだけの接続待ち時間を持たせることによって通信を確立することができ、ルータを含む間欠動作が可能になる。 As a result, when using the wireless node setting device that synchronizes the time with the coordinator 20 when the node 10 is started, and if timing synchronization is established at the time of communication connection, the connection waiting time of only A and C is provided. Communication can be established and intermittent operation including a router becomes possible.
　なお、以上では簡単のためＲＴＣ等による時刻同期を前提としたが、動作間隔に対応する接続待ち時間が確保されればよいので、例えば、内部クロックを用いたカウンタをリセットする方法によって同期を図ってもよい。すなわち、この方法によれば、時刻を保持する回路を持たなくても同期した間欠動作をすることができる。 In the above, for the sake of simplicity, time synchronization by RTC or the like is assumed. However, since it is only necessary to ensure a connection waiting time corresponding to the operation interval, for example, synchronization is achieved by a method of resetting a counter using an internal clock. May be. That is, according to this method, a synchronized intermittent operation can be performed without a circuit for holding time.
　（変形例）
　以上、本発明の実施の形態に係る無線通信システムの管理ノード及び無線通信システムについて説明したが、本発明は、個々の実施の形態には限定されない。本発明の趣旨を逸脱しない限り、当業者が思いつく各種変形を本実施の形態に施したものや、異なる実施の形態における構成要素を組み合わせて構築される形態も、本発明の一つ又は複数の態様の範囲内に含まれてもよい。 (Modification)
The management node and the wireless communication system of the wireless communication system according to the embodiments of the present invention have been described above, but the present invention is not limited to individual embodiments. Unless it deviates from the gist of the present invention, the embodiment in which various modifications conceived by those skilled in the art have been made in the present embodiment, and forms constructed by combining components in different embodiments are also applicable to one or more of the present invention. It may be included within the scope of the embodiments.
　本発明は、無線通信システムの管理ノード及び無線通信システムとして、センサネットワークやアクチュエータの制御ネットワークなどの各種用途の無線ネットワークに広く利用できる。 The present invention can be widely used in various wireless networks such as a sensor network and an actuator control network as a management node and a wireless communication system of a wireless communication system.
　　　１、２　　無線通信システム
　　　１０　　ノード
　　　１１　　通信回路
　　　１２　　送受信部
　　　１３　　ＣＰＵ
　　　１４　　ＲＯＭ
　　　１５　　ＲＡＭ
　　　１６　　アンテナ
　　　１７、１８　　Ｉ／Ｆ
　　　２０　　コーディネータ
　　　２１　　網制御部
　　　３０　　サーバ
　　　４０　　インターネット
　　　５１　　障害物 1, 2 Wireless communication system 10 Node 11 Communication circuit 12 Transmitter / receiver 13 CPU
14 ROM
15 RAM
16 Antenna 17, 18 I / F
20 Coordinator 21 Network Control Unit 30 Server 40 Internet 51 Obstacle

Claims (8)

  1. 　データを中継しない第１のモードとデータを中継する第２のモードとを指示に応じて切り替えて動作する複数の通信ノードで構成された無線通信システムの管理ノードであって、
    　前記管理ノードからの無線通信距離がｎホップ（ｎは自然数）までの通信ノードが判明しているとき、無線通信距離がｎホップである通信ノードのうち、無線通信距離が判明している前記通信ノードに含まれない最多数の通信ノードと直接通信可能な通信ノードに対し、前記第２のモードで動作するよう指示する、
    　無線通信システムの管理ノード。     A management node of a wireless communication system composed of a plurality of communication nodes that operate by switching between a first mode that does not relay data and a second mode that relays data according to an instruction,
    When a communication node having a radio communication distance of up to n hops (n is a natural number) is known from the management node, the communication having a known radio communication distance among communication nodes having a radio communication distance of n hops. Instructing a communication node capable of directly communicating with the largest number of communication nodes not included in the node to operate in the second mode;
    A management node of a wireless communication system.
  2. 　前記管理ノードは、
    　前記管理ノードと直接通信可能な通信ノードを、無線通信距離が１ホップの通信ノードとして分類する第１の処理を行った後、
    　無線通信距離が分類されている中でホップ数が最大の１以上の通信ノードである第１通信ノードのうち、無線通信距離がまだ分類されていない最多数の第２通信ノードと直接通信可能な第１通信ノードに対し、前記第２のモードで動作するよう指示し、前記最多数の前記第２通信ノードを、無線通信距離が前記第１通信ノードのホップ数より大きいホップ数の通信ノードとして分類する第２の処理を、無線通信距離が分類されていない通信ノードがなくなるまで、実行する、
    　請求項１に記載の無線通信システムの管理ノード。     The management node is
    After performing a first process of classifying a communication node capable of directly communicating with the management node as a communication node having a wireless communication distance of 1 hop,
    Among the first communication nodes that are one or more communication nodes having the maximum number of hops among the classified wireless communication distances, it is possible to directly communicate with the largest number of second communication nodes that are not yet classified. The first communication node is instructed to operate in the second mode, and the largest number of the second communication nodes are set as communication nodes having a hop count greater than a hop count of the first communication node. Performing the second process of classifying until there is no communication node whose radio communication distance is not classified,
    The management node of the radio | wireless communications system of Claim 1.
  3. 　前記管理ノードは、
    　前記第１処理において、ビーコン信号を発信し、前記ビーコン信号に応答した通信ノードを、無線通信距離が１ホップの通信ノードとして分類し、
    　前記第２処理において、前記１以上の第１通信ノードに対しビーコン信号の発信を指示し、前記１以上の第１通信ノードの各々から前記ビーコン信号に応答した通信ノードの一覧情報を取得し、前記一覧情報に含まれかつ無線通信距離がまだ分類されていない通信ノードの個数が最多の第１通信ノードに対し、前記第２のモードで動作するよう指示する、
    　請求項２に記載の無線通信システムの管理ノード。     The management node is
    In the first process, a beacon signal is transmitted and a communication node responding to the beacon signal is classified as a communication node having a wireless communication distance of 1 hop,
    In the second process, the one or more first communication nodes are instructed to transmit a beacon signal, and a list of communication nodes responding to the beacon signal is obtained from each of the one or more first communication nodes, Instructing the first communication node having the largest number of communication nodes included in the list information and not yet classified in the wireless communication distance to operate in the second mode;
    The management node of the radio | wireless communications system of Claim 2.
  4. 　前記第１の通信ノードが複数あるとき、
    　前記管理ノードは、１つの第１通信ノードに対しビーコン信号の発信を指示した後、前記ビーコン信号への応答信号を前記１つの第１通信ノードから受信してから、他の第１通信ノードに対しビーコン信号の発信を指示する、
    　請求項３に記載の無線通信システムの管理ノード。     When there are a plurality of the first communication nodes,
    The management node, after instructing one first communication node to transmit a beacon signal, receives a response signal to the beacon signal from the one first communication node, and then sends it to the other first communication node. Instructing the beacon signal to be sent to
    The management node of the radio | wireless communications system of Claim 3.
  5. 　前記第１の通信ノードが複数あるとき、
    　前記管理ノードは、１つの第１通信ノードに対しビーコン信号の発信を指示した後、前記ビーコン信号への応答信号を前記１つの第１通信ノードから受信する前に、他の第１通信ノードに対しビーコン信号の発信を指示する、
    　請求項３に記載の無線通信システムの管理ノード。     When there are a plurality of the first communication nodes,
    The management node directs the transmission of a beacon signal to one first communication node, and then, before receiving a response signal to the beacon signal from the first communication node, sends it to another first communication node. Instructing the beacon signal to be sent to
    The management node of the radio | wireless communications system of Claim 3.
  6. 　前記管理ノードは、所定の条件が満たされると、前記複数の通信ノードを前記第１のモードにした後、前記第２のモードを指示する処理を最初からやり直す、
    　請求項１から５の何れか１項に記載の無線通信システムの管理ノード。     When the predetermined condition is satisfied, the management node sets the plurality of communication nodes to the first mode, and then restarts the process of instructing the second mode from the beginning.
    The management node of the radio | wireless communications system of any one of Claim 1 to 5.
  7. 　データを中継しない第１のモードとデータを中継する第２のモードとを指示に応じて切り替えて動作する複数の通信ノードと、
    　前記複数の通信ノードのうちの少なくとも１つに、前記第２のモードで動作するよう指示する請求項１から６の何れか１項に記載の管理ノードと、
    　を備える無線通信システム。     A plurality of communication nodes that operate by switching between a first mode that does not relay data and a second mode that relays data according to an instruction;
    The management node according to any one of claims 1 to 6, which instructs at least one of the plurality of communication nodes to operate in the second mode;
    A wireless communication system comprising:
  8. 　前記複数の通信ノードの各々は、周期的に起動し、起動時に前記管理ノードとの時刻同期を行うとともに、所定の接続待ち時間待機する間欠動作を行い、
    　通常動作時の接続待ち時間をＡ、間欠動作の起動間隔をＢ、初期設定時および接続が切れたときの接続待ち時間をＣ、設置にかかる期間をＤ、クロック精度をＸとして、Ａ≧ＢＸ、および、Ｃ≧（Ｂ＋Ｄ）Ｘを満たす、
    　請求項７に記載の無線通信システム。     Each of the plurality of communication nodes is periodically activated, performs time synchronization with the management node at the time of activation, and performs an intermittent operation waiting for a predetermined connection waiting time,
    A ≧ BX where A is the connection wait time during normal operation, B is the intermittent operation start interval, C is the connection wait time during initial setting and when the connection is broken, D is the installation period, and X is the clock accuracy. And satisfying C ≧ (B + D) X.
    The wireless communication system according to claim 7.
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