JP5913209B2 - Route control device, sensor node network system, and program - Google Patents

Description

  The present invention relates to a path control device, a sensor node network system and a program, and more particularly to a fixed multi-hop sensor network in which the path control device is fixedly arranged.

  There is a sensor network in which a plurality of sensor-equipped wireless terminals called sensor nodes are scattered in a space and the sensor nodes are coordinated to collect sensor data collectively. In many cases, the sensor network is constructed in the form of a fixed multi-hop sensor network in which a large number of sensor nodes represented by smart meters are fixedly arranged. Each sensor node arranged in a fixed manner operates autonomously.

  In a fixed multi-hop sensor network, sensor information generated at each sensor node is collected at the data collection node in a lump. For this reason, the sensor information is generated at a sensor node arranged far from the data collection node. The data packet including the sensor information is delivered to the data collection node by being sequentially relayed by the sensor node arranged in the upstream direction of the sensor node (a place close to the data collection node). On the other hand, a control packet issued from the data collection node to control the operation in the sensor node is sent to the sensor node designated as the destination by being sequentially relayed from the data collection node by the sensor node arranged in the downstream direction. .

  Thus, each sensor node determines another sensor node as a transmission destination of the packet when relaying the packet. In order to recognize the positional relationship with the other sensor node, Route information including the number of hops from other sensor nodes to the data collection node is acquired. Conventionally, a route information transmission request is broadcast and acquired from surrounding sensor nodes. Then, referring to the number of hops included in the acquired route information, an adjacent node that is a transmission destination of the data packet is determined.

JP 2010-87667 A

  By the way, the route information exchanged between the sensor nodes is not the information itself to be collected in the sensor node network, so the route information is exchanged between the sensor nodes in consideration of the network load and the power usage at each sensor node. I want to suppress the number of to do as much as possible.

  In addition, there is a case where one of the sensor nodes is set as a secondary data collection node and the secondary data collection node functions as the data collection node for some reason, such as when a failure occurs in the data collection node. I am not conscious of the setting of the secondary data collection node. Even if the secondary data collection node is set, when the secondary data collection node functions as the data collection node, route information is exchanged and route learning for sending data packets to the secondary data collection node is performed again. Need to be implemented.

  It is an object of the present invention to reduce the number of exchanges of route information between route control devices as compared with the prior art.

  In addition, even when any sensor node functions as a data collection node instead of the current data collection node, it is possible to cope with a change in the data collection node without newly exchanging route information between the sensor nodes. Another purpose is to do.

The routing control device according to the present invention relays a packet to each destination of the packet, destination information for specifying another routing control device as a destination of the packet when the packet is delivered to the destination, and the destination. Route control information storage means for storing route control information including associated index information referred to when determining the transmission destination of the own device when delivering, an acquisition means for acquiring a transmission target packet, and the route Based on the index information included in the control information, a transmission destination determination unit that determines another path control device that is a transmission destination of the own device when the packet acquired by the acquisition unit is delivered to the destination; and Relay device information added to the packet acquired by the acquisition means, the identification information of the other route control device that relayed the packet, and the other route control device The routing control information setting means for setting the routing control information of the destination in the routing control information storage means based on the relay device information including information that can specify the relay order of each packet, and the packet acquired by the acquisition means Relay device information updating means for updating the relay device information by setting identification information of the own device and information that can specify the order of relaying of the own device in the added relay device information, and the relay device information update A packet transmission unit that transmits the packet whose relay device information has been updated by the unit to the transmission destination determined by the transmission destination determination unit, and is included in the routing control information of the destination based on the transmission result of the packet by the packet transmission unit possess the index information updating means for updating the index information corresponding to the destination is, the, the index information is determined by the destination determining unit The transmission destination determination means includes the number of transmissions in the case where a plurality of other route control devices that are transmission destination candidates are set in the route control information of the packet destination. The smallest other routing control device is determined as a transmission destination .

The index information further includes the number of errors that occurred at the time of transmission or an error rate with respect to the number of times of transmission. When a plurality of transmissions are set, the transmission destination is determined based on the number of transmissions and the number of errors or the error rate .

A sensor node network system according to the present invention includes the path control device according to any one of the above-described inventions, a plurality of sensor nodes that generate data packets including sensor information, and data generated by the sensor nodes. possess a data collection node that collects packets, and the index information included in the routing information storing means stored routing information at each sensor node is determined by the destination determination means in the sensor node Including the number of times the packet has been transmitted to the destination, and the destination determination means in each of the sensor nodes has a plurality of other route control devices that are destination candidates set in the route control information of the destination of the packet, Another route control device having the smallest number of transmissions is determined as a transmission destination .

Further, the transmission destination determination means in each sensor node is the data acquired by the acquisition means based on the index information included in the route control information stored in the route control information storage means in the sensor node. It is characterized in that another sensor node as a transmission destination of its own apparatus when a control packet transmitted from the collection node is delivered to the destination is determined.
The index information included in the path control information stored in the path control information storage unit in each sensor node further includes the number of errors that occurred during transmission or the error rate for the number of transmissions. The transmission destination determination means determines a transmission destination based on the number of transmissions and the number of errors or the error rate when a plurality of other path control devices that are transmission destination candidates are set in the route control information of the packet destination. It is characterized by.

When the program according to the present invention relays and delivers a packet to each destination of the packet, the destination information for specifying another routing control device that is the destination of the packet when the packet is delivered to the destination, and the destination A computer mounted in a route control device having route control information storage means for storing route control information including association with index information referred to when determining the transmission destination of the own device is transmitted as a packet to be transmitted. Based on index information included in the acquisition unit and the route control information to be acquired, another route control device that is a transmission destination of the own device when the packet acquired by the acquisition unit is delivered to the destination is determined. Destination determination means, relay device information added to the packet acquired by the acquisition means, and other route control that relays the packet Route control information setting means for setting the route control information of the destination in the route control information storage means based on relay device information including identification information of the device and information capable of specifying the relay order of the packets of the other route control devices The relay device that updates the relay device information by setting the identification information of the own device and information that can specify the order of relay of the own device in the relay device information added to the packet acquired by the acquisition means Information updating means, packet transmitting means for transmitting the packet whose relay apparatus information has been updated by the relay apparatus information updating means to the transmission destination determined by the transmission destination determining means, based on the packet transmission results by the packet transmission means index information updating means for updating the index information corresponding to the destination included in the routing information of the destination, to function as, The mark information includes the number of times the packet has been transmitted to the transmission destination determined by the transmission destination determination unit, and the transmission destination determination unit includes another route control device that is a transmission destination candidate in the route control information of the packet destination. When a plurality of are set, another route control device having the smallest number of transmissions is determined as a transmission destination .

  According to the present invention, it is possible to reduce the number of exchanges of route information between route control devices as compared with the conventional case.

  In addition, even when any sensor node functions as a data collection node instead of the current data collection node, it is possible to cope with the change of the data collection node without newly exchanging route information between the sensor nodes. it can.

1 is an overall configuration diagram illustrating an example of a sensor network system according to the present invention. It is a hardware block diagram of the computer mounted in the node in this Embodiment. It is a block block diagram of the node in this Embodiment. It is a flowchart which shows the process at the time of starting performed by the node in this Embodiment. FIG. 2 is a diagram illustrating a range in which a node J can perform wireless communication in the sensor network system illustrated in FIG. 1. It is a figure which shows the example of a setting of the routing control information registered into the routing table by performing the process at the time of starting in this Embodiment. It is a flowchart which shows the packet relay process in this Embodiment. It is a figure which shows the example of the relay route of the data packet produced | generated by the node X in the sensor network system shown in FIG. It is a figure which shows the data structural example of the data packet which the node J received in the sensor network system shown in FIG. It is a figure which shows the data structural example of the data packet which the node J transmits in the sensor network system shown in FIG. It is a figure which shows the example of a setting of the route control information registered into the routing table in this Embodiment. It is a figure which shows the data structural example of the data packet which the node J received in the sensor network system shown in FIG. It is a figure which shows the data structural example of the data packet which the node J transmits in the sensor network system shown in FIG. It is a figure which shows the route | root by which a data packet is transmitted from the node X to the gateway 2 in the sensor network system shown in FIG.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is an overall configuration diagram showing an example of a sensor network system according to the present invention. The sensor network system in the present embodiment has a sensor network composed of a plurality of sensor nodes 10 and a gateway (GW) 2. Each sensor node 10 in the present embodiment is a wireless terminal with a sensor having a routing function, which is formed by mounting a sensor on the route control device according to the present invention. In the present embodiment, it is assumed that the sensor node 10 is realized by a smart meter or the like that is fixedly dispersed in the sensor network system. Each sensor node 10 transmits sensor information including sensor data measured by a sensor included in the sensor node 10 to the gateway 2 and sends a data packet including sensor information generated in the other sensor nodes 10 to the gateway 2. Function as a relay node to relay. Although a plurality of sensor nodes A to X are shown in FIG. 1, the number of sensor nodes 10 is not limited to this. In the following description, the node 10 is described in common with each sensor node (hereinafter simply referred to as “node”), and the nodes A to X and alphabetical characters are used in describing the specific node 10. . Each node 10 is arranged at a position where it can wirelessly communicate with at least one node 10, and a route (route) 3 can be formed between the node 10 or the gateway 2 capable of communication.

  The gateway 2 is a data collection node that collects data packets including the sensor information generated by each sensor node 10 and corresponds to a coordinator in IEEE 802.15.4 and ZigBee (registered trademark).

  FIG. 2 is a hardware configuration diagram of a computer mounted on the node 10 according to the present embodiment. In this embodiment, the computer mounted on the node 10 can be realized by a general-purpose hardware configuration that has existed in the past. That is, as shown in FIG. 2, the computer connects the CPU 21, ROM 22, RAM 23, network controller 26 provided as a communication means, and an input / output controller 28 that connects a sensor 27 for measuring power consumption to the internal bus 29. Configured.

  The gateway 2 in the present embodiment may be realized with a conventional hardware configuration. That is, although the sensor 27 may not be mounted, the basic configuration of the computer may be illustrated in the same manner as in FIG. Further, a computer equipped with a mouse provided as input means, a keyboard, and a display provided as display means may be connected by wire or wirelessly.

  Here, the types of packets exchanged between the nodes (node 10 and gateway 2) will be described.

  In the present embodiment, there are a data packet, a control packet, and a route control packet as packets that flow on the route 3 between nodes. The “data packet” is a sensor network having a basic function of collecting information of sensors obtained by the measurement of the sensor 27 by the nodes 27 in the gateway 2 as a basic function. Each node 10 directly or indirectly transmits the sensor information to the gateway 2. Packet to transmit automatically. The “control packet” is a packet for transmitting control information for the gateway 2 to perform operation control such as a sensor function to the node 10 to be controlled. The “route control packet” is a packet that is exchanged between nodes in order for each node 10 to establish a route 3 with a peripheral node. In the case of this embodiment, the Hello packet and Hello Reply packet used for exchanging information on the number of hops to the gateway 2 correspond to this. The route information exchanged in the route control packet is control information used to determine the relay route of the data packet and the control packet. Therefore, the transmission / reception amount in the sensor network system is minimized. The increase in network load and the increase in power usage at each node 10 should be prevented. Note that the “peripheral node” refers to a node that can receive a Hello packet transmitted by broadcast using the wireless communication function of the node itself.

  FIG. 3 is a block diagram of the node 10 in the present embodiment. Note that components not used in the description of the present embodiment are omitted from the drawings. The node 10 in the present embodiment includes a sensor unit 11, a packet generation unit 12, a packet reception unit 13, a packet transmission unit 14, a communication control unit 15, and a routing table holding unit 16. The sensor unit 11 is realized by the sensor 27. When the node 10 is a smart meter, the sensor unit 11 generates sensor information including measured power usage data. The packet generation unit 12 generates a data packet including sensor information sent from the sensor unit 11. The packet receiver 13 receives a packet sent from another node 10. Packets received by the packet receiver 13 are data packets generated by other nodes 10, control packets transmitted from the gateway 2, and route control packets transmitted from peripheral nodes among the other nodes 10. The packet transmission unit 14 is provided as a packet transmission unit. The packet whose relay device information (hereinafter also referred to as “relay node information”) is updated by the communication control unit 15 is transmitted to the transmission destination determined by the communication control unit 15. Send.

  The communication control unit 15 includes a packet type determination unit 151, a transmission destination determination unit 152, a table update unit 153, a packet update unit 154, and an initial setting unit 155, and implements a packet communication control function in the node 10. When the communication control unit 15 functioning as an acquisition unit acquires a packet from the packet generation unit 12 or the packet reception unit 13, the packet type determination unit 151 determines the type of the acquired packet. The transmission destination determination unit 152 is provided as a transmission destination determination unit, and based on the index information included in the route control information set in the routing table holding unit 16, the acquired packet is designated as a designated destination. The other node 10 which is the transmission destination of the own node at the time of delivery is determined. The table update unit 153 is provided as a route control information setting unit, and is relay node information added to the acquired packet, and the identification information (node ID) of the other node 10 that relayed the packet and the other Based on the relay node information including information that can specify the relay order of each node 10, the destination route control information is set in the routing table holding unit 16. The table updating unit 153 is also provided as index information updating means, and updates the index information corresponding to the transmission destination included in the routing control information of the destination based on the packet transmission result by the packet transmission unit 14. The packet updating unit 154 is provided as a relay device information updating unit, and sets information that can identify the node ID of the own node and the order in which the own node relays to the relay node information added to the acquired packet. To update the relay node information. The initial setting unit 155 performs initial setting in the routing table by executing a startup process when the own node is started.

  The routing table holding unit 16 is provided as route control information storage means, and stores the route control information in a table format. A data setting example of the routing table that stores this route control information in a table format is shown in FIGS. In the routing table, routing control information in which the own node hop number, node ID, hop number, signal strength, number of trials, and error rate are associated with each destination of the packet to be transmitted is set. The destination of each packet can be specified by referring to the packet header. The local node hop count is the hop count from the local node to the destination. The node ID is transmission destination information that identifies another node that is a transmission destination of the packet when the packet is delivered to the destination, and a node ID that identifies the other node is set. The number of hops is the number of hops from the node specified by the node ID (hereinafter also referred to as “destination node”) to the destination node. The “destination node” means a node to which the node directly transmits a packet, and the “destination” or “destination node” is a node designated as a packet destination. Yes, it refers to the node that is the final destination of the packet. The signal strength is the signal strength with the destination node. In the case of wireless, electric field strength is sufficient. The number of trials and the number of errors are index information that is referred to in order to determine a transmission destination when a packet is delivered to the destination. The number of trials indicates the number of times that the packet is transmitted to the transmission destination determined by the transmission destination determination unit 152. The number of errors is the number of errors that occurred when a packet was transmitted to the transmission destination determined by the transmission destination determination unit 152. In the present embodiment, the transmission destination is determined using the error rate, and this error rate is calculated by dividing the number of errors by the number of trials.

  As illustrated in FIGS. 6 and 10, the fact that a plurality of route control information is set for one destination means that there are a plurality of routes for sending packets to the destination. ing. Each node 10 determines the packet transmission destination with reference to the setting value of the index information when determining the packet transmission destination from the plurality of paths. This transmission destination determination process will be described later.

  Each component 11-15 in each node 10 is implement | achieved by cooperation operation | movement of the program mounted on the computer mounted in the node 10, and CPU21 mounted in the computer. The routing table holding unit 16 is realized by the RAM 3.

  The gateway 2 is the destination (final destination) of the data packet and the source of the control packet. Further, the gateway 2 exchanges routing packets with the node 10 capable of wireless communication, but relays the packet. There is no. Therefore, it is not necessary to mount the packet relay function of the node 10, but it has the same components as the components 12 to 16 of the node 10 described above in order to determine the transmission destination of the control packet.

  Further, the program used in this embodiment can be provided not only by communication means but also by storing it in a computer-readable recording medium such as a CD-ROM or DVD-ROM. A program provided from a communication unit or a recording medium is installed in a computer, and various processes are realized by the CPU 21 of the computer sequentially executing the program.

  Next, the operation in this embodiment will be described. First, the startup process that is performed when the node 10 starts up and participates in the sensor network system will be described with reference to the flowchart shown in FIG.

  When the node is activated, no routing control information is set and registered in the routing table. Therefore, it is necessary to collect route information in order to recognize the route 3 for transmitting the data packet to the gateway 2. For this purpose, the communication control unit 15 in the node 10 broadcasts the Hello packet to the packet transmission unit 14 (step 101).

  The peripheral node that has received the Hello packet unicasts the HelloReply packet in which the route information including the number of hops to the gateway 2 of the node is set to the node that has transmitted the Hello packet at the time of activation (hereinafter referred to as “activation node”). To do.

  When the activation node receives the Hello Reply packet sent from each peripheral node (Step 102), the activation node sets and registers the path control information in the routing table based on the route information included in the Hello Reply packet (Step 103).

  Subsequently, the activation node participates in the sensor network by executing a participation procedure in the sensor network (step 103). Since this participation procedure may be the same as before, description thereof is omitted.

  When the participation procedure is completed, the activation node broadcasts a Hello packet in which the number of hops from the own node to the gateway 2 (the number of own node hops) is set, thereby notifying the neighboring nodes (step 105). The number of local node hops is determined as follows. Here, the case where the node J in the sensor network system shown in FIG. 5 is the start node will be described as an example. Note that a range 31 indicated by a broken line in FIG. 5 indicates a range in which the node J can perform wireless communication. In FIG. 5, nodes C, D, I, K, O, and P are nodes installed at positions where wireless communication with the node J is possible, and are nodes around the node J.

  When the route information is collected by broadcasting the Hello packet in Step 101, HelloReply packets are returned from the plurality of peripheral nodes C, D, I, K, O, and P. As described above, when HelloReply packets are sent from a plurality of nodes 10, the number of hops (the number of own node hops) from the own node to the destination node (in this case, the gateway 2) is the smallest hop in the acquired route information. Obtained by adding 1 to the number. In the sensor network system illustrated in FIG. 5, FIG. 6 illustrates a setting example of the routing control information that is set and registered in the routing table when the node J receives the Hello Reply packet. As apparent from FIG. 5, nodes C and D have route information including a hop number 1, nodes I and K have route information including a hop number 2, and nodes O and P have routes information having a hop number 3. The Hello Reply packet in which the information is set is transmitted. As a result, the route control information shown in FIG. 6 is set and registered in the routing table. However, in this embodiment, only the route control information for the peripheral nodes is set and registered.

  As described above, the node J obtains the number of hops of its own node by adding 1 to the smallest number of hops in the acquired route information. As is clear from FIG. 6, the smallest number of hops is obtained. The peripheral nodes are nodes C and D, and the number of hops is 1. Therefore, the node J has the nodes C and D closest to the destination as parents, and positions its own node immediately below it. As a result, the number of node hops to the gateway 2 at the node J is 2.

  The node J measures the signal strength between the peripheral nodes at the time of packet exchange with the peripheral nodes by a measuring unit (not shown), and registers and registers the signal strength in the routing table. Further, since the node J has not yet relayed the packet, 0 is set as the initial value for the number of trials and the number of errors.

  In the present embodiment, the broadcast that increases the network load is performed in the startup process, but as will be apparent from the following description, the broadcast is not performed thereafter to set the routing control information in the routing table. .

  Next, packet relay processing in the node 10 that is performed after the initial setting is completed and joined to the sensor network system will be described with reference to the flowchart shown in FIG. First, a so-called uplink relay process in which a data packet transmitted from another node 10 is delivered to the gateway 2 that is the destination of the data packet will be described. Here, a case where the node J relays a packet will be described as an example.

  In the node J, when the packet receiving unit 13 receives a packet sent from any of the nodes 10 (step 111), the communication control unit 15 acquires the packet. The packet type determination unit 151 refers to the information indicating the destination and transmission source of the packet header of the acquired packet, so that the acquired packet is a data packet transmitted from another node 10 whose destination is the gateway 2 Is determined. In the case of a data packet, subsequently, the transmission destination determination unit 152 determines the transmission destination of the data packet as follows (step 112). FIG. 10 is a diagram illustrating an example of setting a routing table. At this time, it is assumed that the route control information illustrated in FIG. 10 is set. The process for setting and registering the route control information shown in FIG. 10 will be described later.

  In general, as a relay destination (transmission destination) of a data packet, a node with the lowest cost is often selected. That is, the route with the lowest cost (adjacent node having the lowest cost) is selected as the destination by referring to the number of hops of the destination candidate or the number of hops and signal strength. However, if the route with the lowest cost is used as a transmission destination selection criterion, the route to be selected is fixed. In the case of adopting a method such as this embodiment that does not frequently exchange route information, if a route is fixed, if a failure occurs on the fixed route, a bypass route is searched. It may take a lot of processing and time to find out.

  Therefore, in this embodiment, index information for determining a transmission destination when a packet is delivered to a destination is set separately from the cost, and the transmission destination is determined with reference to the index information. In the present embodiment, the number of trials and an error rate calculated from the number of trials and the number of errors are used as index information. Here, for convenience of explanation, a case will be described in which a transmission destination is determined using only the number of trials.

  That is, when the destination determination unit 152 recognizes that the destination of the data packet to be relayed is the gateway 2, the node ID set in the records 41 to 46 whose destination registered in the routing table is the gateway 2 is C, The nodes D, I, K, O, and P are selected as transmission destination candidates. Of these nodes C, D, I, K, O, and P, the node having the smallest number of trials is determined as the transmission destination.

  However, according to the example shown in FIG. 10, the number of own node hops to the gateway 2 at the node J is 2, so that the number of nodes equal to or more than the number of own node hops to the destination, that is, the nodes I, K, O and P are excluded from selection targets, and only nodes C and D smaller than the number of local node hops may be selected. Then, the node C, D having the smaller number of trials is determined as the transmission destination. Of course, if all of the nodes C and D smaller than the number of node hops cannot transmit a packet due to a communication failure or the like, the nodes I, K, O, and P may be selected, but the packet is transmitted to the node J. This may be notified to the transmission source node (node O or node P in the configuration shown in FIG. 1), and a node other than node J may be selected again as the transmission destination.

  When the transmission destination of the data packet is determined, the table update unit 153 then acquires the relay node information included in the packet header of the data packet to be relayed, and refers to the acquired relay node information Route control information is generated and registered in the routing table (step 113). The routing control information setting registration process performed by the table update unit 153 will be described with reference to FIGS.

  FIG. 8 is an overall configuration diagram of the same sensor network system as in FIG. 1, but two routes 32 and 33 are shown as routes through which data packets transmitted from the node X flow. In the route 32, the data packet transmitted from the node X is sent to the gateway 2 via the node V, the node T, the node P, the node J, and the node C. On the other hand, in the route 33, the data packet transmitted from the node X is sent to the gateway 2 through the node U, the node S, the node O, the node J, and the node C.

  9A shows the data packet received by the node J when the data packet transmitted from the node X to the gateway 2 is delivered through the route 32. FIG. 9B shows the data packet shown in FIG. 9A as the node. Each data packet is shown when it is transmitted after J is updated. The data packet 40 includes a header 41 and a payload 42. In the present embodiment, one of the features is that the header 43 includes an area 43 for setting relay node information. In the area 43 for storing the relay node information, an area 44 in which a node ID is set as identification information of the node that relayed the data packet, and the number of nodes registered in the area 44, that is, the data packet is relayed An area 45 in which the number of nodes is set is provided. Note that the node X is a generation source of the data packet and may not strictly relay the data packet. However, the node X is one of the nodes existing on the route for sending the data packet to the gateway 2. Therefore, the term “relay” is interpreted in a broad sense, and the node X is also regarded as one of the relay nodes and included in the relay node information. Thereby, the node located on the route 32 can be specified by referring to the relay node information.

  Even if the “relay” is strictly interpreted, since the header 41 is set with information specifying the source and destination of the data packet, the presence of the node X on the route 32 is not possible. I can grasp.

  In this embodiment, the node IDs are registered in the area 44 in the order relayed from the data packet generation source. That is, the arrangement order of the node IDs in the area 44 corresponds to information that can specify the relay order of the data packets. Thereby, the relay order can be grasped at a glance. Of course, by adding information indicating the relaying order to each node ID, the node IDs do not have to be registered in the region 44 in the relaying order.

  Referring to the arrangement of the data packets in the region 44 shown in FIG. 9A, it can be seen that the node IDs are registered in the relay order of the data packets transmitted from the generation source node X.

  When the table update unit 153 acquires the data packet shown in FIG. 9A, the table update unit 153 first generates routing control information in order from the last node P registered in the area 44 to the top, and registers it in the routing table. That is, first, assuming that a packet addressed to the node P is received, the route control information of the record 46 is generated. For this purpose, the node P is set as the destination of the routing control information. In order to send the packet to the node P, the packet may be transmitted to the node P. Therefore, the node ID “P” of the node P is set as the node ID of the path control information. Further, since the node P is an adjacent node of the node J, the node P sets 1 as the number of hops of its own node in the path control information. Further, since the node P is the node P itself, 0 is set to the hop count of the route control information. The signal strength FIpp measured by a measuring unit (not shown) is set as the signal strength of the routing control information when the data packet is received. At this time, since the packet has not been relayed yet, the initial value 0 is set to the number of trials and the number of errors. The table update unit 153 generates the route control information of the record 46 as described above and registers it in the routing table.

  Subsequently, the table update unit 153 generates the route control information of the record 47 having the destination as the node T that relayed the data packet immediately before the last node P. For this purpose, the node T is set as the destination of the route control information. In order to deliver the packet to the node T, it is only necessary to transmit the packet to the node P. Therefore, the node ID “P” of the node P is set as the node ID of the path control information. Further, since the route control information for the destination node T is only the record 47, the number of local node hops is set to 2 which is obtained by adding 1 to the hop number 1 of the record 47. Further, since the node P is an adjacent node of the node T, 1 is set to the number of hops of the route control information. As the signal strength of the routing control information, the signal strength FIpt measured by a measuring unit (not shown) is set when the data packet is received. At this time, the signal intensities FIpp and FIpt are the same because they are measured at the same time. At this time, since the packet is not relayed yet, the initial value 0 is set to the number of trials and the number of errors. The table updating unit 153 generates the route control information of the record 47 as described above and registers it in the routing table.

  Since the route control information of the record 48 for the node V and the route control information of the record 49 for the node X are also generated in the same manner as described above, description thereof will be omitted.

  When the routing table is updated as described above, the packet updating unit 154 subsequently adds the node ID of the own node, in this example, the node J, to the end of the area 44 of the received data packet. The number of nodes set in the area 45 is updated to 5 by adding 1 to the current value. In this way, the relay node information added to the data packet to be relayed is updated (step 114). A setting example of the relay node of the data packet updated by this processing is shown in FIG. 9B.

  When the relay node information added to the data packet is updated as described above, the packet transmission unit 14 determines the data packet with the updated relay node information according to the instruction from the communication control unit 15 by the transmission destination determination unit 152. It transmits to the destination node that has been sent (step 115). In this example, the data is transmitted to the node C. Then, the communication control unit 15 is notified of the result of the transmission process, that is, whether the packet transmission is normally completed. Further, a measurement unit (not shown) measures the signal strength with the node C and notifies the communication control unit 15 of the signal strength.

  When the communication control unit 15 receives the notification, the table update unit 153 updates the route control information corresponding to the corresponding transmission destination. In this example, since the data packet is transmitted to the node C on the route 32, the table update unit 153 adds 1 to the number of trials of the record 41 corresponding to the node C. In addition, when the process does not end normally, 1 is added to the number of errors. In this way, the table update unit 153 updates the index information (step 116). The table updating unit 153 further overwrites and updates the FIc with the received signal strength.

  In this embodiment, the determination of the transmission destination of the data packet (step 112), the update of the routing table (step 113), and the update of the data packet (step 114) are performed according to the above procedure. It is not always necessary to carry out in this order. That is, the determination of the transmission destination of the data packet (step 112) and the update of the data packet (step 114) may be performed before the process of transmitting the data packet (step 115). Further, the update of the routing table (step 113) may be performed before the process of updating the index information (step 116).

  11A shows the data packet received by the node J when the data packet transmitted from the node X to the gateway 2 is delivered through the route 33 shown in FIG. 8, and FIG. 11B shows the data packet shown in FIG. 11A. The data packets when the data packet is transmitted after the node J is updated are shown. In the case of the route 32, the routing control information of the records 46 to 49 in the routing table shown in FIG. 10 is set. However, in the case of the route 33, the data packet shown in FIG. The route control information of records 50 to 53 is set in the routing table. Here, as is apparent from the routing table shown in FIG. 10, since the route 32 and the route 33 are routes through which the data packet of the same node X flows, the routing control information for the node X is the destination. A plurality of records 49 and 50 are set and registered.

  The packet relay process in this embodiment is executed as described above. In the present embodiment, the node J has been described as a representative, but the data packet is finally delivered to the gateway 2 by performing the same processing in the other nodes 10.

  Further, the gateway 2 does not relay the data packet when it receives the data packet, but generates the routing control information based on the relay node information included in the received data packet and, like the relay node, the routing table of its own node. Register settings to. As a result, the gateway 2 can know what route the data packet has reached, so the routing table is also suitable for use in network maintenance such as automatic generation of a network configuration diagram.

  As described above, since the node X refers to the number of trials in the routing table of its own node, the node X selects the destination node having the smallest number of trials from among the nodes U, V, and W. Not specified. Similarly, the other nodes A to W that relay the data packet from the node X refer to the number of trials in the routing table of the own node to determine the destination of the data packet. Therefore, the destination is also unique in each relay node. Not specified. As a result, the data packet transmitted from the node X is delivered to the gateway 2 through various routes as illustrated in FIG.

  By the way, when the data packet shown in FIG. 9A is transmitted from the node X, it is a data packet that flows in the upstream direction, reaching the node J via the nodes V, T, and P. If the node J receives a control packet addressed to the node X in the downlink direction, if the node J is relayed in turn to the path opposite to the uplink direction, that is, the nodes P, T, and V, the control packet It can be delivered to. Similarly, when node J receives a packet addressed to node V in the downstream direction, the control packet can be delivered to node V if it is relayed in turn to nodes P and T. The same applies to the node T and further to the node P.

  From the above, when relaying an upstream data packet, the node J generates routing control information based on the relay node information included in the data packet and registers it in the routing table. When relaying control packets addressed to the nodes X, V, T, and P in the direction, it is not necessary to send route information and confirm the positional relationship with surrounding nodes. According to the setting example shown in FIG. 10, when a control packet addressed to the node X, V, T, or P is received, the node P may be selected as the transmission destination.

  As described above, in this embodiment, the relay node information is included in the header 41 of the packet, and when relaying the data packet to be transmitted in the upstream direction, the relay node information added to the data packet is referred to and It is characterized in that route control information used for determining a direction transmission destination is generated in advance and registered in a routing table. In particular, it is possible to set and register route control information related to a plurality of downstream nodes for relaying one data packet. In the present embodiment, the route control information can be generated without using a route control packet such as a Hello packet that is not directly related to the exchange of the data packet including the sensor information.

  Next, a case where the node J itself is a data packet generation source will be described.

  When the sensor unit 11 generates sensor data by measurement, the packet generation unit 12 generates a data packet including sensor information obtained from the sensor data. When the communication control unit 15 acquires the packet generated by the packet generation unit 12, the packet type determination unit 151 refers to the packet header of the acquired packet, and the received packet is destined for the gateway 2. Since the transmission source is the node J, it is determined that the data packet is generated by the own node.

  The subsequent processing may be performed in substantially the same manner as when data packets from other nodes 10 are relayed. However, since the relayed node ID is not registered in the relay node information of the data packet, there is no record that is set and registered in the routing table in step 113. In step 114, the packet updating unit 154 sets the data packet by adding the node ID of the own node to the area 44 of the data packet and setting 1 to the number of nodes set in the area 45.

  When the packet type determining unit 151 determines that the type of the packet received by the packet receiving unit 13 is a route control packet, the communication control unit 15 may perform the same processing as before. The routing packet used in the present embodiment may have the same data format as before, and no relay node information is included in the packet header.

  Here, a case where a control packet is transmitted from the gateway 2 to one of the nodes, a case where the packet flows in a so-called downlink direction will be described. This process is basically the same as steps 112 to 116 shown in FIG. The data structure of the control packet may be the same as the data packet illustrated in FIGS.

  When the gateway 2 determines a transmission destination when transmitting a control packet, the gateway 2 refers to the number of trials in the routing table of its own node. For example, when a control packet addressed to the node X is generated and transmitted, the destination registered in the routing table of the own node refers to the path control information of the node X. Assuming that each record having the node IDs of nodes A, B, C, and D is set and registered in the routing control information of the node X, the destination determination unit in the gateway 2 has the smallest number of trials. Determine the node as the destination. Then, the packet updating unit sets the control packet by adding the node ID of the own node to the area 44 of the control packet and setting 1 to the number of nodes set in the area 45. The packet transmission unit transmits the control packet to the transmission destination determined by the transmission destination determination unit.

  Since the packet relay process in the relay node that relays the control packet is the same as the process described with reference to FIG. 7, detailed description thereof is omitted.

  For example, when the node J relays the control packet, if the destination of the control packet is the node V, the control packet may be transmitted to the node P with reference to the record 48 of the routing table illustrated in FIG. If the destination of the control packet is the node U, the control packet may be transmitted to the node O with reference to the record 53 of the routing table illustrated in FIG.

  After the packet transmission, the table updating unit 153 updates the index information corresponding to the transmission destination included in the routing control information of the destination based on the transmission result of the packet. Specifically, 1 is added to the number of trials. In addition, the table updating unit 153 updates the signal strength corresponding to the transmission destination with the signal strength measured by a measurement unit (not shown) at the time of packet transmission. If an error occurs, add 1 to the number of errors and reselect a different transmission destination, or notify the transmission source node that transmitted the control packet to the local node, and notify other nodes. You can reselect the node.

  For example, in the node J, the control packet whose destination is the node V is transmitted to the node P. In this case, the signal strength for the node P is all signal strengths FIp, FIpp, FIpt, FIpv for the node P. FIpx may be updated, but only the signal strength FIpv corresponding to the transmission destination of the control packet may be updated for reasons such as reduction of processing load.

  According to the present embodiment, since the routing control information destined for the downlink node has already been generated in the packet relay processing for relaying the data packet, the processing for generating the routing control information for relaying the control packet Need not be implemented separately.

  In this embodiment, the routing table in each relay node is set and registered with the routing control information destined for the downstream node by relaying the data packet, but flows in the downstream direction as described above. By relaying the control packet, the routing control information destined for the upstream node is set and registered.

  By the way, the fact that the path control information is set and registered in the same routing table in the same record format for both the upstream and downstream directions can be said to require no distinction between the upstream and downstream packets flowing directions. For example, the node X is set as a sub-gateway (sub-data collection node), and the system configuration is configured so that the node X functions as a gateway (data collection node) instead of the gateway 2 for some reason, such as when the gateway 2 fails. Suppose you change it. If the direction is given, the up and down directions are reversed from the system illustrated in FIG. Even in such a case, according to the present embodiment, data can be transferred to the gateway node X by referring to the existing routing table without resetting the routing control information by exchanging route information. Packets can be delivered and node X can also send control packets.

  In the above description, the case where only the number of trials is referred to as index information when the transmission destination is determined has been described as an example. If the node with the smallest number of trials is selected, it is easy to avoid the concentration of packets that may cause congestion. However, the index information is not limited to the number of trials. For example, the number of errors and the error rate may be used instead of the number of trials. However, the number of errors, etc. may be fixed if the error does not occur, so the selected destination may be fixed. You may give priority to index information, such as using an error rate, when a node with the same number of times exists.

  In the present embodiment, the number of trials and the number of errors are recorded as index information, the index information is updated each time a packet is relayed, and the transmission destination is determined by referring to the index information. That is, in this embodiment, since an index that can be updated by relaying a packet or the like is used so that the transmission destination of the packet is not uniquely specified, the number of trials is an index that can be changed. An index other than the error rate may be used.

  Further, when the node 10 is removed from the sensor network, information indicating that fact may be broadcast to the neighboring nodes, and the route control information related to the nodes may be deleted from the routing table of each neighboring node.

  In addition, as a sensor-equipped wireless terminal (sensor node) included in the sensor network in the present embodiment, a smart meter or the like that measures power consumption can be considered, but a sensor-equipped wireless terminal that measures sensor data other than power consumption The route control device may be applied to the wireless terminal, or the route control device may be applied to a wireless terminal that handles data other than the sensor data.

  In the present embodiment, the case where the route control device is applied to a wireless terminal has been described as an example. However, the route control device may also be applied to a wired connection device such as a PLC (Power Line Communication). . In other words, it is not necessary to limit the communication method used for communication between the route control devices to wireless. A network system may be constructed by connecting the route control devices by wire, or a network in which wire and wireless are mixed. A system may be constructed.

  2 gateways, 3 routes, 10 sensor nodes, 11 sensor units, 12 packet generation units, 13 packet reception units, 14 packet transmission units, 15 communication control units, 16 routing table holding units, 21 CPU, 22 ROM, 23 RAM, 26 Network controller, 27 sensors, 28 I / O controller, 29 internal bus, 151 packet type determination unit, 152 destination determination unit, 153 table update unit, 154 packet update unit, 155 initial setting unit.

Claims (6)

For each destination of the packet, the destination information for specifying another routing control device that is the transmission destination of the packet when delivering the packet to the destination, and the transmission destination of the own device when relaying and delivering the packet to the destination Route control information storage means for storing route control information including associated index information referred to when determining;
An acquisition means for acquiring a packet to be transmitted;
Based on the index information included in the route control information, transmission destination determination means for determining another route control device that is a transmission destination of the own device when the packet acquired by the acquisition means is delivered to the destination; and ,
Relay device information added to the packet acquired by the acquisition means, the identification information of the other route control device that relayed the packet, and information that can specify the relay order of the packets of the other route control device Route control information setting means for setting the destination route control information in the route control information storage means based on the relay device information including:
Relay device information for updating the relay device information by setting identification information of the own device and information that can specify the order of relaying the own device in the relay device information added to the packet acquired by the acquisition unit Update means;
A packet transmission means for transmitting the packet in which the relay apparatus information is updated by the relay apparatus information update means to the transmission destination determined by the transmission destination determination means;
Index information updating means for updating index information corresponding to the transmission destination included in the routing control information of the destination based on the transmission result of the packet by the packet transmission means;
I have a,
The index information includes the number of times the packet has been transmitted to the transmission destination determined by the transmission destination determination means,
The destination determination unit determines, as a transmission destination, another path control device having the smallest number of transmissions when a plurality of other route control devices that are transmission destination candidates are set in the route control information of the packet destination. A path control device characterized by that. The route control device according to claim 1,
The index information further includes the number of errors that occurred during transmission or the error rate for the number of transmissions ,
The transmission destination determination unit determines a transmission destination based on the number of transmissions and the number of errors or the error rate when a plurality of other path control devices that are transmission destination candidates are set in the route control information of the packet destination. A path control device characterized by that. A plurality of sensor nodes that have the path control device according to claim 1 and generate data packets including sensor information;
A data collection node for collecting data packets generated by each of the sensor nodes;
I have a,
The index information included in the route control information stored in the route control information storage unit in each sensor node includes the number of times the packet is transmitted to the transmission destination determined by the transmission destination determination unit in the sensor node,
The transmission destination determination means in each sensor node transmits another path control device with the smallest number of transmissions when a plurality of other route control devices that are transmission destination candidates are set in the route control information of the packet destination. A sensor node network system characterized by being determined as a destination . In the sensor node network system according to claim 3 ,
The transmission destination determination unit in each sensor node is the data collection node acquired by the acquisition unit based on the index information included in the path control information stored in the path control information storage unit in the sensor node. A sensor node network system, which determines another sensor node as a transmission destination of its own device when sending a control packet transmitted from the destination to the destination. In the sensor node network system according to claim 4,
The index information included in the path control information stored in the path control information storage means in each sensor node further includes the number of errors that occurred at the time of transmission or the error rate for the number of times of transmission,
The transmission destination determination means in each sensor node transmits based on the number of transmissions and the number of errors or the error rate when a plurality of other path control devices that are transmission destination candidates are set in the packet destination route control information. A sensor node network system characterized by determining a destination. For each destination of the packet, the destination information for specifying another routing control device that is the transmission destination of the packet when delivering the packet to the destination, and the transmission destination of the own device when relaying and delivering the packet to the destination A computer mounted in a route control device having route control information storage means for storing route control information that includes reference information that is referred to when determining is associated with,
An acquisition means for acquiring a packet to be transmitted;
Based on the index information included in the route control information, a transmission destination determination unit that determines another route control device that is a transmission destination of the own device when the packet acquired by the acquisition unit is delivered to the destination,
Relay device information added to the packet acquired by the acquisition means, the identification information of the other route control device that relayed the packet, and information that can specify the relay order of the packets of the other route control device Route control information setting means for setting the destination route control information in the route control information storage means based on the relay device information including:
Relay device information for updating the relay device information by setting identification information of the own device and information that can specify the order of relaying the own device in the relay device information added to the packet acquired by the acquisition unit Update means,
A packet transmission means for transmitting a packet whose relay apparatus information has been updated by the relay apparatus information update means to a transmission destination determined by the transmission destination determination means;
Index information updating means for updating index information corresponding to the transmission destination included in the routing control information of the destination based on the transmission result of the packet by the packet transmission means;
To function as,
The index information includes the number of times the packet has been transmitted to the transmission destination determined by the transmission destination determination means,
The destination determination unit determines, as a transmission destination, another path control device having the smallest number of transmissions when a plurality of other route control devices that are transmission destination candidates are set in the route control information of the packet destination. A program characterized by that .

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