Communication system, central device, route control method, and route control program

Abstract

A communication system (100) is provided with a central device (1), an aggregation device (2), and a plurality of nodes (3). Each of the plurality of nodes (3) is installed so as to be capable of directly communicating with an adjacent node, which is one or more other nodes (3), and transmits data directly or via an adjacent node to the aggregation device (2). The central device (1) calculates, assuming each of the plurality of nodes (3) as a node (3) of interest, a sum total of the communication time of the node (3) of interest and the communication time of adjacent nodes pertaining to the node (3) of interest. The central device (1) controls an uplink path for transmitting data from each of the plurality of nodes (3) to the aggregation device (2) on the basis of the total time.

Description

Communication system, central device, route control method, and route control program

[0001] The present disclosure relates to a routing control technology that prevents load concentration on some nodes in a multi-hop network.

[0002] In fields such as AMI or sensor networks, wireless multi-hop networks are constructed in which multiple nodes are housed under a certain aggregation device, and the aggregation device collects data from the multiple nodes housed under its control. AMI stands for Advanced Metering Infrastructure. Systems such as AMI or sensor networks require a high data collection rate from nodes. Therefore, it is necessary to prevent a decrease in the collection rate due to network load.

[0003] A conventional load balancing method in a wireless multi-hop network is a method of determining the load based on the number of nodes under its control (see Patent Document 1). Specifically, the number of nodes under an aggregation device is calculated, and if the number of nodes is equal to or greater than a threshold, it is determined that the load is high. If the load is determined to be high, some of the nodes under that aggregation device are switched to be under the control of another aggregation device. This achieves load balancing.

[0004] International Publication No. 2014 / 068665

[0005] Unlike conventional load balancing methods in wireless multi-hop networks, it is not possible to accurately estimate the load simply by looking at the number of nodes under control. This is because some nodes communicate a large amount of data, while others communicate only a small amount of data. As a result, it is not possible to perform appropriate load balancing. The present disclosure aims to control the upstream path for transmitting data from a node to an aggregation device in a more appropriate manner, thereby enabling appropriate load balancing.

[0006] The communication system according to the present disclosure is a communication system comprising an aggregation device and a plurality of nodes, each of which is installed so as to be able to communicate directly with one or more other adjacent nodes, and which transmits data to the aggregation device directly or via the adjacent nodes; a time calculation unit which calculates, for each of the plurality of nodes as a target node, the total time of the communication time of the target node and the communication time of the adjacent nodes for the target node; and a route control unit which controls an uplink route for transmitting data from each of the plurality of nodes to the aggregation device based on the total time calculated by the time calculation unit.

[0007] In this disclosure, for each node, the upstream path is controlled using the sum of the communication time of the node and the communication time of the adjacent node. The sum represents the load of each node appropriately, making it possible to achieve appropriate load balancing.

[0008] 1 is a configuration diagram of a communication system 100 according to a first embodiment. A functional configuration diagram of a central device 1 according to the first embodiment. A functional configuration diagram of an aggregation device 2 according to the first embodiment. A functional configuration diagram of a node 3 according to the first embodiment. A hardware configuration diagram of each device, i.e., the central device 1, the aggregation device 2, and the node 3 according to the first embodiment. A flowchart of a route establishment process according to the first embodiment. A diagram showing an example of a route according to the first embodiment. A configuration diagram of a signal according to the first embodiment. A flowchart of a route control process according to the first embodiment. An explanatory diagram of a specific example of a route control process according to the first embodiment. An explanatory diagram of a specific example of a route control process according to the first embodiment.

[0009] First Embodiment. ***Description of Configuration*** The configuration of a communication system 100 according to the first embodiment will be described with reference to FIG. 1. The communication system 100 includes a central device 1, which is a communication management device, one or more aggregation devices 2, and a plurality of nodes 3. In FIG. 1, the communication system 100 includes aggregation devices 2-1 and 2-2 as the aggregation devices 2. The communication system 100 also includes nodes 3-1 to 3-7 as the nodes 3. The communication system 100 can configure a wireless multi-hop network. Although FIG. 1 shows two aggregation devices 2 and seven nodes 3, the numbers of aggregation devices 2 and nodes 3 are not limited to the example shown in FIG. 1.

[0010] One or more aggregation devices 2 and multiple nodes 3 form a wireless multi-hop network with one of the aggregation devices 2 as the root. In Fig. 1, the lines connecting the aggregation devices 2-1 and 2-2 and the nodes 3-1 to 3-7 indicate wireless links. Of the lines connecting the aggregation devices 2-1 and 2-2 and the nodes 3-1 to 3-7, the solid lines indicate first-priority transmission routes, and the dashed lines indicate second-priority transmission routes.

[0011] Here, an example will be described in which the communication system 100 is a wireless multi-hop network. However, the communication system 100 may be a multi-hop network using power line communication or the like.

[0012] The functional configuration of the central device 1 according to the first embodiment will be described with reference to Fig. 2. The central device 1 includes, as functional components, a transmitter / receiver 11, a communication control unit 12, and a communication time storage unit 13. The communication control unit 12 includes a signal control unit 121, a time calculation unit 122, and a route control unit 123. The communication time storage unit 13 records the communication time for each aggregation device 2 and the communication time for each node 3.

[0013] The transmitter / receiver 11 communicates with the aggregation device 2. The communication control unit 12 controls communication between each aggregation device 2 and each node 3. Specifically, in the communication control unit 12, the signal control unit 121 generates a signal to be transmitted to the aggregation device 2 or node 3. If the generated signal is addressed to the aggregation device 2, the signal control unit 121 causes the transmitter / receiver 11 to transmit the signal to the destination aggregation device 2. If the generated signal is addressed to node 3, the signal control unit 121 identifies the aggregation device 2 corresponding to the node 3 and causes the transmitter / receiver 11 to transmit the signal to the identified aggregation device 2. Furthermore, upon receiving a signal transmitted from the aggregation device 2 or node 3, the communication control unit 12 performs a predetermined process using the signal. Specifically, if the received signal contains data such as sensor data, the signal control unit 121 temporarily stores the data and causes the transmitter / receiver 11 to transmit the data to a system higher than the central device 1 at a predetermined timing. Furthermore, upon receiving a specific signal, the time calculation unit 122 calculates the communication time of each aggregation device 2 and each node 3, and records the calculated communication time in the communication time storage unit 13. Then, the route control unit 123 controls the upstream route for transmitting data from each node 3 to the aggregation device 2, based on the communication time recorded in the communication time storage unit 13. Note that the time calculation unit 122 may calculate the communication time of only the node 3.

[0014] The functional configuration of the aggregation device 2 according to the first embodiment will be described with reference to FIG. 3 . The aggregation device 2 includes, as functional components, a transmitter / receiver 21, a communication control unit 22, a network configuration information storage unit 23, and a communication time storage unit 24. The communication control unit 22 includes a signal control unit 221 and a time calculation unit 222. The network configuration information storage unit 23 stores downstream route information and adjacent node information. The downstream route information is information indicating a downstream route corresponding to an upstream route of node 3, which is obtained based on a signal received from node 3. A downstream route corresponding to an upstream route means that the downstream route is the opposite direction of the upstream route. The adjacent node information is information indicating an adjacent node of node 3, which is obtained based on a signal received from node 3. The communication time storage unit 13 stores the communication time for each aggregation device 2 and the communication time for each node 3. Note that the communication time storage unit 24 may not be provided, if necessary.

[0015] The transmitter / receiver 21 communicates with the node 3. When the transmitter / receiver 21 receives a signal from the node 3, it outputs the signal to the communication control unit 22. The transmitter / receiver 21 also transmits various signals to the node 3 based on instructions from the communication control unit 22. The transmitter / receiver 21 also communicates with the central device 1. When the transmitter / receiver 21 receives a signal from the central device 1, it outputs the signal to the communication control unit 22. The transmitter / receiver 21 also transmits various signals to the central device 1 based on instructions from the communication control unit 22. The communication control unit 22 receives a signal transmitted from the node 3 from the transmitter / receiver 21. If the signal is an upstream communication control signal used for route construction, the signal control unit 221 then records a downstream route corresponding to the upstream route stored in the signal as downstream route information in the network configuration information storage unit 23. If the signal transmitted from the node 3 includes data such as sensor data, the signal control unit 221 temporarily stores the data and causes the transmitter / receiver 21 to transmit the data to the central device 1 at a predetermined timing. Furthermore, upon receiving a specific signal, the time calculation unit 222 calculates the communication time between the aggregation device 2 and each subordinate node 3, and records the calculated communication time in the communication time storage unit 24. Note that the time calculation unit 222 may calculate the communication time for only the node 3.

[0016] The functional configuration of the node 3 according to the first embodiment will be described with reference to Fig. 4. The node 3 includes, as functional components, a transmitter / receiver 31, a communication controller 32, and a network configuration information storage unit 33. The network configuration information storage unit 33 stores upstream route information indicating upstream routes and adjacent node information indicating adjacent nodes.

[0017] The transmitter / receiver 31 communicates with an external device, such as another node 3 or the aggregation device 2, in the wireless multi-hop network. When the transmitter / receiver 31 receives a signal from an external device, it outputs the signal to the communication control unit 32. Furthermore, the transmitter / receiver 31 transmits the signal to the external device based on an instruction from the communication control unit 32. If the signal is addressed to an external device, the communication control unit 32 forwards the signal to the destination external device by causing the transmitter / receiver 31 to transmit the signal toward the destination external device. Furthermore, when the communication control unit 32 receives data such as sensor data, it refers to upstream route information stored in the network configuration information storage unit 33 and causes the transmitter / receiver 31 to transmit the data to an adjacent external device in the upstream direction. As each node 3 forwards the data, it arrives at the destination external device.

[0018] Referring to Figure 5, the hardware configuration of each of the central device 1, aggregation device 2, and node 3 according to the first embodiment will be described. Each device includes a control circuit 40 having a processor 41 and memory 42, a transmitter 43, and a receiver 44. The processor 41 is specifically a CPU or MPU. CPU stands for Central Processing Unit. MPU stands for Micro Processor Unit. The memory 42 specifically includes semiconductor memory such as RAM and ROM, a magnetic disk, etc. RAM stands for Random Access Memory. ROM stands for Read Only Memory.

[0019] The transmitting / receiving units 11, 21, and 31 are realized by a transmitter 43 and a receiver 44. The communication control units 12, 22, and 32 are realized by a control circuit 40. Specifically, the communication control units 12, 22, and 32 are realized by the processor 41 executing a communication program stored in a memory 42 for realizing the operation of the communication control unit 12. The communication program may be provided by a recording medium or a communication medium. The communication time storage units 13 and 24 and the network configuration information storage units 23 and 33 are realized by the memory 42. The communication time storage unit 13 may be realized by a memory separate from the memory 42 included in the control circuit 40.

[0020] At least one of the central device 1, aggregation device 2, and node 3 may be a dedicated circuit such as an FPGA or ASIC instead of the control circuit 40. FPGA is an abbreviation for Field-Programmable Gate Array. ASIC is an abbreviation for Application Specific Integrated Circuit. The control circuit 40 and the dedicated circuit are collectively called a processing circuit.

[0021] The central device 1 is realized by a computer system. Therefore, the central device 1 may include a display unit such as a monitor or a display, and an input unit such as a keyboard or a mouse, in addition to the control circuit 40, the transmitter 43, and the receiver 44.

[0022] ***Description of Operation*** The operation of the communication system 100 according to the first embodiment will be described with reference to Figures 6 to 11. The operation procedure of the communication system 100 according to the first embodiment corresponds to the route control method according to the first embodiment. Furthermore, the program that realizes the operation of the communication system 100 according to the first embodiment corresponds to the route control program according to the first embodiment.

[0023] The route establishment process according to the first embodiment will be described with reference to Fig. 6. The route establishment process is a process executed when an aggregation device 2 is newly connected to the communication system 100. Fig. 6 shows the process when an aggregation device 2-1 is newly connected to the communication system 100.

[0024] (Step S1: Connection Establishment Process) The transmitter / receiver 21 of the aggregation device 2-1 performs connection establishment process with the central device 1. When the transmitter / receiver 21 completes the connection establishment, it notifies the communication control unit 22 to that effect.

[0025] (Step S2: Transmission of construction signal) The transmitter / receiver 21 of the aggregation device 2-1 transmits a wireless multi-hop construction signal for constructing a route in the wireless multi-hop network with the node 3. Specifically, when the signal controller 221 of the communication controller 22 is notified by the transmitter / receiver 21 that the connection establishment is complete, the signal controller 221 generates a wireless multi-hop construction signal. The signal controller 221 causes the transmitter / receiver 21 to transmit the wireless multi-hop construction signal by broadcast. The wireless multi-hop construction signal stores the aggregation device ID of the aggregation device 2-1, which is the root of the upstream communication, identification information of the node that transmitted the wireless multi-hop construction signal, and the number of hops to the aggregation device 2-1. Here, the identification information of the node that transmitted the wireless multi-hop construction signal is the aggregation device ID of the aggregation device 2-1, and the number of hops is 0. The aggregation device ID is identification information for identifying each aggregation device 2. ID is an abbreviation for IDentifier.

[0026] 6, node 3-1 receives a wireless multi-hop establishment signal directly from aggregation device 2-1. Although not shown, node 3-2 also receives a wireless multi-hop establishment signal directly from aggregation device 2-1 and performs the same operation as node 3-1 described below.

[0027] (Step S3: Construction Signal Transfer Processing) Upon receiving the wireless multihop construction signal, the transmitter / receiver 31 of node 3-1 updates the identification information of the node that transmitted the wireless multihop construction signal and the number of hops to the aggregation device 2-1, and broadcasts the multihop route construction signal. Note that the transmitter / receiver 31 may determine that the wireless multihop construction signal has been received only when it is received with a reception strength equal to or greater than a lower limit. Specifically, upon receiving the wireless multihop construction signal, the transmitter / receiver 31 outputs the wireless multihop construction signal to the communication control unit 32. Upon receiving the wireless multihop construction signal, the communication control unit 32 extracts the identification information of the node that transmitted the wireless multihop construction signal and the number of hops to the aggregation device 2-1. The communication control unit 32 updates the identification information of the node that transmitted the wireless multihop construction signal received from the transmitter / receiver 31 to the node ID of node 3-1. The node ID is identification information for identifying each node 3. Furthermore, the communication control unit 32 updates the hop count in the wireless multi-hop establishment signal received from the transmitting / receiving unit 31 to a value obtained by adding 1 to the extracted hop count. The hop count extracted from the data received from the transmitting / receiving unit 31 is 0. Therefore, the hop count is updated to 1. The communication control unit 32 causes the transmitting / receiving unit 31 to broadcast the updated wireless multi-hop establishment signal.

[0028] (Step S4: Upstream Route Recording Process) Upon receiving the wireless multihop establishment signal, the communication control unit 32 of the node 3-1 records the upstream route information and adjacent node information in the network configuration information storage unit 33. Specifically, the communication control unit 32 records the identification information of the source node extracted from the wireless multihop establishment signal in step S3 and the hop count obtained by adding 1 to the extracted hop count in the network configuration information storage unit 33 as upstream route information related to the upstream route. The identification information of the source node becomes the identification information of the next node on the upstream route. Here, the aggregation device ID of the aggregation device 2-1 and the hop count of 1 are recorded as the upstream route information. Furthermore, the communication control unit 32 records the identification information of the source node extracted from the wireless multihop establishment signal in step S3 in the network configuration information storage unit 33 as adjacent node information. Here, the aggregation device ID of the aggregation device 2-1 is recorded as adjacent node information.

[0029] (Step S5: Control Signal Transmission Processing) Upon receiving the wireless multi-hop establishment signal, the communication control unit 32 of node 3-1 transmits an upstream communication control signal. Specifically, the communication control unit 32 identifies the root of the upstream communication from the aggregation device ID included in the wireless multi-hop establishment signal received from the transceiver unit 31 in step S3. Here, the root of the upstream communication is identified as the aggregation device 2-1. Then, the communication control unit 32 generates an upstream communication control signal addressed to the aggregation device 2-1. At this time, the communication control unit 32 stores, in the upstream communication control signal, the node ID of node 3-1 as the identification information of the source node and the parent terminal identification information. The communication control unit 32 causes the transceiver unit 31 to transmit the upstream communication control signal according to the upstream route information recorded in step S4. That is, the communication control unit 32 causes the transceiver unit 31 to transmit the upstream communication control signal addressed to the aggregation device 2-1 to the next node on the upstream route. Here, the next node on the upstream route is the destination aggregation device 2-1.

[0030] The communication control unit 32 may perform the following processing. After receiving a wireless multi-hop establishment signal, the communication control unit 32 waits for a reference time without transmitting an upstream communication control signal. If the communication control unit 32 receives a wireless multi-hop establishment signal from another aggregation device 2 or another node 3 within the reference time, the communication control unit 32 selects the aggregation device 2 or node 3 with the best communication quality based on the signal strength of the received wireless multi-hop establishment signal. Then, the communication control unit 32 transmits an upstream communication control signal to the selected node 3. This makes it possible to select an upstream route with good communication quality. At this time, aggregation devices 2 or nodes 3 with communication quality equal to or higher than a reference level may be recorded in the network configuration information storage unit 33 as candidates for the upstream route. For example, the aggregation device 2 or node 3 with the best communication quality may be recorded in the network configuration information storage unit 33 as first-priority upstream route information, and the aggregation device 2 or node 3 with the second best communication quality may be recorded in the network configuration information storage unit 33 as second-priority upstream route information.

[0031] The communication control unit 32 may transmit information about the uplink communication control signal together with a signal for transmitting sensor data that is periodically transmitted. In other words, when the communication control unit 32 receives a wireless multi-hop establishment signal, the communication control unit 32 may transmit a signal that is periodically transmitted together with necessary information as the uplink communication control signal, rather than transmitting an uplink communication control signal.

[0032] (Step S6: Downstream route recording process) The transmitter / receiver 21 of the aggregation device 2-1 receives the upstream communication control signal transmitted in step S5. Then, the signal controller 221 of the communication controller 22 records the downstream route information and adjacent node information in the network configuration information storage unit 23. Specifically, upon receiving the upstream communication control signal, the transmitter / receiver 21 outputs the upstream communication control signal to the communication controller 22. The signal controller 221 of the communication controller 22 records the parent terminal identification information in the upstream communication control signal in the network configuration information storage unit 23 as downstream route information and adjacent node information to the node 3 indicated by the identification information of the source node 3.

[0033] (Step S7: Construction Signal Transfer Processing) The transmitter / receiver 31 of node 3-2 receives the wireless multi-hop construction signal transmitted in step S3. Then, similar to step S3, the transmitter / receiver 31 of node 3-2 updates the identification information of the node that transmitted the wireless multi-hop construction signal and the number of hops to the aggregation device 2-1, and broadcasts a multi-hop route construction signal. Specifically, upon receiving the wireless multi-hop construction signal, the transmitter / receiver 31 outputs the wireless multi-hop construction signal to the communication control unit 32. Upon receiving the wireless multi-hop construction signal, the communication control unit 32 extracts the identification information of the node that transmitted the wireless multi-hop construction signal and the number of hops to the aggregation device 2-1. The communication control unit 32 updates the identification information of the node that transmitted the wireless multi-hop construction signal received from the transmitter / receiver 31 to the node ID of node 3-2. Furthermore, the communication control unit 32 updates the number of hops in the wireless multi-hop construction signal received from the transmitter / receiver 31 to a value obtained by adding 1 to the extracted number of hops. The hop count extracted from the data received from the transmitting / receiving unit 31 is 1. Therefore, the hop count is updated to 2. The communication control unit 32 causes the transmitting / receiving unit 31 to broadcast the updated wireless multi-hop establishment signal.

[0034] (Step S8: Upstream route recording process) As in step S4, when the communication control unit 32 of node 3-2 receives the wireless multi-hop establishment signal, it records the upstream route information and adjacent node information in the network configuration information storage unit 33. Here, the node ID of node 3-1 and the number of hops, 2, are recorded as the upstream route information. In addition, the node ID of node 3-1 is recorded as the adjacent node information.

[0035] (Step S9: Control Signal Transmission Processing) Upon receiving the wireless multi-hop establishment signal, the communication control unit 32 of node 3-2 transmits an upstream communication control signal. Specifically, the communication control unit 32 identifies the root of the upstream communication from the aggregation device ID included in the wireless multi-hop establishment signal received from the transmission / reception unit 31 in step S7. Here, the root of the upstream communication is identified as the aggregation device 2-1. Then, the communication control unit 32 generates an upstream communication control signal addressed to the aggregation device 2-1. At this time, the communication control unit 32 stores, in the upstream communication control signal, the node ID of node 3-2 as the identification information of the node from which the upstream communication originated and the parent terminal identification information. The communication control unit 32 causes the transmission / reception unit 31 to transmit the upstream communication control signal in accordance with the upstream route information recorded in step S8. That is, the communication control unit 32 causes the transmission / reception unit 31 to transmit the upstream communication control signal addressed to the aggregation device 2-1 to the next node on the upstream route. Here, the next node on the upstream route is node 3-1.

[0036] (Step S10: Identification information update process) The transmitter / receiver 31 of node 3-1 receives the upstream communication control signal. Then, the communication control unit 32 of node 3-1 updates the parent terminal identification information. Specifically, when the transmitter / receiver 31 receives the upstream communication control signal, it outputs the signal to the communication control unit 32. The communication control unit 32 updates the parent terminal identification information to the node ID of node 3-1.

[0037] (Step S11: Control signal forwarding process) The transmitter / receiver 31 of node 3-1 forwards the upstream communication control signal, whose parent terminal identification information has been updated in step S10. Specifically, the transmitter / receiver 31 transmits the upstream communication control signal, whose parent terminal identification information has been updated, in accordance with the upstream route information. In other words, the communication control unit 32 transmits the upstream communication control signal addressed to the aggregation device 2-1 to the next node on the upstream route. In this case, the next node on the upstream route is the destination aggregation device 2-1.

[0038] (Step S12: Downstream route recording process) The transmitter / receiver 21 of the aggregation device 2-1 receives the upstream communication control signal transmitted in step S11. Then, the signal controller 221 of the communication controller 22 records the downstream route information and adjacent node information in the network configuration information storage unit 23. Specifically, upon receiving the upstream communication control signal, the transmitter / receiver 21 outputs the upstream communication control signal to the communication controller 22. The signal controller 221 of the communication controller 22 records the parent terminal identification information in the upstream communication control signal in the network configuration information storage unit 23 as downstream route information and adjacent node information to the node 3 indicated by the identification information of the source node 3.

[0039] FIG. 6 shows the processing for only some of the aggregation devices 2 and some of the nodes 3. However, in reality, the processing is executed for each node 3 that can communicate with the aggregation device 2-1. Then, by executing the route construction processing not only for the aggregation device 2-1 but also for the aggregation device 2-2, an upstream route from each node 3 and a downstream route to each node 3 are set, as shown in FIG. 7, for example. In FIG. 7, the upstream route is indicated by an arrow. The downstream route is in the opposite direction to the upstream route. Then, a signal including data such as sensor data is transmitted from each node 3 to the aggregation device 2 along the upstream route. The aggregation device 2 temporarily stores the data, and at a predetermined timing, transmits the data to the central device 1 by including it in a node notification signal.

[0040] (Step S13: Node notification transmission process) The transmitter / receiver 21 of the aggregation device 2-1 transmits a node notification signal to the central device 1 at a predetermined timing. Specifically, the signal controller 221 of the communication controller 22 generates a node notification signal at a predetermined timing. At this time, the signal controller 221 sets data such as sensor data that was included in the signal transmitted from the node 3 and that was temporarily stored in the node notification signal. The signal controller 221 also stores the aggregation device ID of the aggregation device 2-1 in the node notification signal as identification information of the transmission source aggregation device 2. The signal controller 221 causes the transmitter / receiver 21 to transmit the node notification signal to the central device 1.

[0041] (Step S14: Time Calculation Process) The transmitter / receiver 11 of the central device 1 receives the node notification signal transmitted in step S13. Then, the communication control unit 12 of the central device 1 calculates the communication time of each aggregation device 2 and each node 3. Specifically, upon receiving the node notification signal, the transmitter / receiver 11 outputs the node notification signal to the communication control unit 12. Upon receiving the node notification signal, the time calculation unit 122 of the communication control unit 12 calculates the communication time for each aggregation device 2 and each node 3. At this time, for each aggregation device 2, the time calculation unit 122 calculates the total time of the communication time of the target aggregation device 2 and the communication time of an adjacent node for the target aggregation device 2. Similarly, for each node 3, the time calculation unit 122 calculates the total time of the communication time of the target node 3 and the communication time of an adjacent node for the target node 3. The time calculation unit 122 records the total time for each aggregation device 2 and each node 3 in the communication time storage unit 13. 7, the time calculation unit 122 calculates the total time of the communication time of node 3-1 and the communication time of each of node 3-1's adjacent nodes. Assume that node 3-1's adjacent nodes are aggregation device 2-1, node 3-4, and node 3-5. In this case, the time calculation unit 122 calculates the total time of node 3-1 as the total of the communication time of node 3-1, the communication time of aggregation device 2-1, the communication time of node 3-4, and the communication time of node 3-5.

[0042] A method for calculating communication time will now be described. A certain aggregation device 2 or a certain node 3 is set as a target device, and the communication time for the target device is to be calculated. The time calculation unit 122 calculates the communication time for the target device by dividing the transmission volume, including transfers of the target device, during a reference period by the data rate of the target device. The data rates of each aggregation device 2 and each node 3 are assumed to be specified in advance.

[0043] As shown in Figure 8, when data such as sensor data is transmitted from each node 3, the signal contains information such as source identification information, destination identification information, adjacent node identification information, data, and data size information. The source identification information is the node ID of the source node 3. The destination identification information is the aggregation device ID of the destination aggregation device 2. The adjacent node identification information is the node ID of the adjacent node adjacent to the source node 3. The data is sensor data, etc. The data size information is the amount of data contained in the signal.

[0044] As shown in FIG. 8 , when data such as sensor data is transmitted from each node 3, data size information is included in the signal. By referring to this data size information, the time calculation unit 122 can identify the amount of data transmitted from each node 3. Furthermore, since the upstream path from each node 3 is identified, it is possible to identify which node 3 forwarded the sensor data transmitted from each node 3. Therefore, it is also possible to identify the amount of data transmitted by each node 3. Therefore, the time calculation unit 122 can identify the amount of transmission, including forwarding, for each aggregation device 2 and each node 3. In the case of the amount of transmission, including forwarding, for node 3-1 in FIG. 7 , the amount of data transmitted from node 3-1 is identified from the data size information included in the sensor data transmitted from node 3-1. Furthermore, it can be seen from the upstream path that node 3-1 is forwarding the sensor data transmitted from node 3-4 and the sensor data transmitted from node 3-5. Therefore, it can be seen that the amount of data being transferred by node 3-1 is the sum of the amount of data being sent from node 3-4 and the amount of data being sent from node 3-5.

[0045] 8 , the signal transmitted from each node 3 includes identification information of the adjacent node of that node 3. The time calculation unit 122 can identify the adjacent node for each node 3 using the identification information of the adjacent node. Similarly, for aggregation device 2, the adjacent node for aggregation device 2 can be identified from the identification information of the adjacent node included in the signal transmitted from aggregation device 2.

[0046] (Step S15: Route Control Processing) The route control unit 123 in the communication control unit 12 of the central device 1 controls the upstream route for transmitting data from each node 3 to the aggregation device 2 based on the total time calculated in step S14.

[0047] The route control process (step S15 in FIG. 6) according to the first embodiment will be described with reference to FIG. 9. (Step S151: Excess Device Determination Process) The route control unit 123 determines whether or not there is an aggregation device 2 whose total time is equal to or greater than the threshold, by referring to the total time recorded in the communication time storage unit 13. If there is an aggregation device 2 whose total time is equal to or greater than the threshold, the route control unit 123 proceeds to step S152. On the other hand, if there is no aggregation device 2 whose total time is equal to or greater than the threshold, the route control unit 123 ends the process.

[0048] (Step S152: Excess node determination process) The route control unit 123 refers to the total time recorded in the communication time storage unit 13 and determines whether or not there is a node 3 whose total time is equal to or greater than the threshold under the aggregation device 2 whose total time is determined to be equal to or greater than the threshold in step S151. If there is a node 3 whose total time is equal to or greater than the threshold, the route control unit 123 proceeds to step S153. On the other hand, if there is no node 3 whose total time is equal to or greater than the threshold, the route control unit 123 ends the process.

[0049] (Step S153: Margin Node Determination Process) The route control unit 123 selects, as a selected node, each of one or more nodes 3 determined in step S152 to have a total time equal to or greater than the threshold. The route control unit 123 references the total time recorded in the communication time storage unit 13 and determines whether or not a slack node whose total time is less than the threshold exists as an adjacent node of the selected node. If a slack node whose total time is less than the threshold exists as an adjacent node of any of the selected nodes, the route control unit 123 proceeds to step S154. On the other hand, if no slack node whose total time is less than the threshold exists as an adjacent node of any of the selected nodes, the route control unit 123 ends the process.

[0050] (Step S154: Destination switching process) The route control unit 123 selects one of the selected nodes in which a slack node exists as the node 3 to be switched for the upstream route. For the node 3 to be switched, the route control unit 123 sets the destination when transmitting data to the aggregation device 2 to the slack node. This controls the upstream route from the node 3 to be switched to the aggregation device 2. At this time, the route control unit 123 causes the transmitter / receiver unit 11 to transmit a switching control signal instructing the switching of the destination, with the node 3 to be switched as the destination, on the downstream route corresponding to the upstream route before switching. This switching control signal includes identification information of the slack node that will be the new destination.

[0051] A specific example of the route control process (step S15 in FIG. 6) according to the first embodiment will be described with reference to FIGS. 7 and 10. It is assumed that an upstream route is set as shown in FIG. 7. At this time, it is assumed that nodes 3-1, 3-4, and 3-5, which transmit data toward the aggregation device 2-1, have larger traffic volumes than other nodes 3. Then, in step S151, it is determined that the total time of the aggregation device 2-1 is equal to or greater than a threshold. In step S152, it is determined that the total time of nodes 3-1, 3-4, and 3-5 is equal to or greater than a threshold. In step S153, it is determined that node 3-2, which is an adjacent node of node 3-5, is a slack node whose total time is less than the threshold. Then, as shown in FIG. 10, in step S154, node 3-5 is selected as the node 3 to be switched for the upstream route, and the destination of node 3-5's data is switched from node 3-1, which has the first priority, to node 3-2, which has the second priority. At this time, as shown in FIG. 11 , the route control unit 123 causes the transmitter / receiver unit 11 to transmit a switching control signal instructing the switching target node 3-5 to switch the destination on the downlink route corresponding to the uplink route before switching shown in FIG. 7 . This switching control signal includes identification information of node 3-2, which is a spare node. Upon receiving the switching control signal, the communication control unit 32 of node 3-5 switches the destination of the uplink route to node 3-2, which has second priority. Note that the downlink route for transmitting the switching control signal is not limited to the downlink route corresponding to the uplink route before switching, and may be another route. The downlink route for transmitting the switching control signal may be, for example, the downlink route corresponding to the uplink route after switching. By changing the destination of node 3-5 from node 3-1 to node 3-2, the load on node 3-1 and aggregation device 2-1, where traffic is concentrated, is reduced.

[0052] The destination node 3 can be switched by switching the IP address indicating the destination node 3. The destination node 3 can also be switched by switching the frequency used for data transmission instead of the IP address.

[0053] ***Effects of First Embodiment*** As described above, the communication system 100 according to the first embodiment controls the upstream path for each node 3 using the total time of the communication time of that node 3 and the communication time of an adjacent node. The total time appropriately represents the load of each node 3. Therefore, it is possible to realize appropriate load distribution.

[0054] 6, the time calculation unit 122 in the communication control unit 12 of the central device 1 calculates the total time for each aggregation device 2 and each node 3. However, the time calculation unit 222 in the communication control unit 22 of each aggregation device 2 may calculate the total time. In this case, when transmitting a node notification signal, each aggregation device 2 calculates the total time for itself and the total time for each subordinate node 3. Then, the total time for itself and each node 3 is included in the node notification signal and transmitted to the central device 1.

[0055] <Modification 2> In the first embodiment, the total time is calculated and the upstream route is controlled each time a node notification signal is received. However, the total time may be calculated and the upstream route may be controlled each time a threshold number or more of node notification signals transmitted from any aggregation device 2 are received. This makes it possible to reduce the processing load required for calculating the total time and controlling the route.

[0056] <Modification 3> In the first embodiment, in the route control process (step S15 in FIG. 6 ), it is determined in step S151 whether or not there is an aggregation device 2 whose total time is equal to or greater than the threshold. If there is an aggregation device 2 whose total time is equal to or greater than the threshold, it is determined in step S152 whether or not there is a node 3 whose total time is equal to or greater than the threshold among the nodes 3 subordinate to the aggregation device 2 whose total time is equal to or greater than the threshold. However, the process of step S151 may be omitted. In this case, it is determined in step S152 for all nodes 3 whether or not there is a node 3 whose total time is equal to or greater than the threshold.

[0057] <Modification 4> In the first embodiment, the upstream route is controlled when there is a node 3 whose total time is equal to or greater than a threshold. However, the route control unit 123 may control the upstream route so that the total time of each node 3 is averaged, regardless of whether the total time is equal to or greater than a threshold. That is, in step S15 of FIG. 6 , the route control unit 123 controls the upstream route for at least some of the nodes 3 so that the total time of each aggregation device 2 and each node 3 is averaged.

[0058] <Modification 5> In the first embodiment, the upstream route is controlled using the total time. The route control unit 123 may control the upstream route using, in addition to the total time, at least one of the following indicators: the reception strength of signals from other nodes 3 at each node 3, the number of hops from the aggregation device 2, and the data rate of each node 3. For example, an evaluation value of the upstream route may be calculated from the total time and other indicators, and the upstream route may be controlled based on the evaluation value.

[0059] The various aspects of the present disclosure are summarized below as appendices. (Appendix 1) A communication system including an aggregation device and a plurality of nodes, each of which is installed so as to be able to directly communicate with one or more other adjacent nodes, and which transmits data to the aggregation device directly or via the adjacent nodes, a time calculation unit that calculates, for each of the plurality of nodes as a target node, a total time of the communication time of the target node and the communication time of the adjacent nodes for the target node, and a route control unit that controls an upstream route for transmitting data from each of the plurality of nodes to the aggregation device based on the total time calculated by the time calculation unit. (Appendix 2) The communication system according to Appendices 1, wherein the route control unit selects, as a selected node, a node whose total time is equal to or greater than a threshold, and, if there is a slack node whose total time is less than the threshold as the adjacent node for the selected node, controls the upstream route for transmitting data from the selected node to the aggregation device by setting the slack node as the destination when transmitting data from the selected node to the aggregation device. (Supplementary Note 3) The communication system according to Supplementary Note 1, wherein the route control unit controls the upstream route so that the total time for each of the plurality of nodes is averaged. (Supplementary Note 4) The communication system includes a plurality of aggregation devices that transmit data received from the plurality of nodes to a higher-level device, wherein the plurality of nodes transmit data to one of the plurality of aggregation devices, and the time calculation unit, treating each of the plurality of aggregation devices as a target aggregation device, calculates a total time of the communication time of the target aggregation device and the communication time of a node installed so as to be able to directly communicate with the target aggregation device, and the route control unit controls an upstream route for transmitting data from each of the plurality of nodes to one of the plurality of aggregation devices based on the total time calculated for the plurality of aggregation devices. (Supplementary Note 5) The communication system according to Supplementary Note 4, wherein the route control unit controls the upstream route by changing the destination of a node on the upstream route that transmits data to the excess aggregation device when there is an excess aggregation device whose total time is equal to or greater than a threshold.(Supplementary Note 6) The communication system according to Supplementary Note 5, wherein the route control unit selects a node, of which the total time is equal to or greater than a threshold, as a selected node from among the nodes transmitting data to the excess device, and when a slack node, of which the total time is less than the threshold, exists as the adjacent node of the selected node, sets the slack node as a destination when transmitting data from the selected node to the aggregation device. (Supplementary Note 7) The communication system according to Supplementary Note 4, wherein the route control unit controls the uplink route so that the total time for each of the plurality of aggregation devices and each of the plurality of nodes is averaged. (Supplementary Note 8) A communication system comprising an aggregation device and a plurality of nodes, wherein each of the plurality of nodes is installed so as to be able to communicate directly with one or more other nodes that are adjacent nodes, and transmits data to the aggregation device directly or via the adjacent nodes, said central device controlling an upstream route for transmitting data from each of the plurality of nodes to the aggregation device, said central device comprising: a time calculation unit which calculates, with each of the plurality of nodes as a target node, the total time of the communication time of the target node and the communication time of the adjacent nodes for the target node; and a route control unit which controls the upstream route based on the total time calculated by the time calculation unit. (Supplementary Note 9) A route control method for controlling an upstream route for transmitting data from each of the plurality of nodes to the aggregation device in a communication system comprising an aggregation device and a plurality of nodes, wherein each of the plurality of nodes is installed so as to be able to communicate directly with one or more other nodes, which are adjacent nodes, and transmits data to the aggregation device directly or via the adjacent nodes, the route control method treating each of the plurality of nodes as a target node, calculating the total time of the communication time of the target node and the communication time of the adjacent node for the target node, and controlling the upstream route based on the total time.(Supplementary Note 10) A route control program for controlling an upstream route for transmitting data from each of the plurality of nodes to the aggregation device, for a communication system comprising an aggregation device and a plurality of nodes, wherein each of the plurality of nodes is installed so as to be able to communicate directly with one or more other nodes that are adjacent nodes, and transmits data to the aggregation device directly or via the adjacent nodes, the route control program causing a computer to execute: a time calculation process for calculating, with each of the plurality of nodes as a target node, the total time of the communication time of the target node and the communication time of the adjacent nodes for the target node; and a route control process for controlling the upstream route based on the total time calculated by the time calculation process.

[0060] The embodiments and modifications of the present disclosure have been described above. Some of these embodiments and modifications may be combined and implemented. Furthermore, one or more of them may be implemented partially. Note that the present disclosure is not limited to the above embodiments and modifications, and various modifications are possible as needed.

[0061] 100 Communication system, 1 Central device, 11 Transmitter / receiver, 12 Communication control unit, 121 Signal control unit, 122 Time calculation unit, 123 Route control unit, 13 Communication time storage unit, 2 Aggregation device, 21 Transmitter / receiver, 22 Communication control unit, 221 Signal control unit, 222 Time calculation unit, 23 Network configuration information storage unit, 24 Communication time storage unit, 3 Node, 31 Transmitter / receiver, 32 Communication control unit, 33 Network configuration information storage unit, 40 Control circuit, 41 Processor, 42 Memory, 43 Transmitter, 44 Receiver.

Claims

1. A communication system comprising an aggregation device and multiple nodes, Each of the aforementioned plurality of nodes is installed to be able to communicate directly with one or more other adjacent nodes, and transmits data to the aggregation device directly or via the adjacent nodes. A time calculation unit that calculates the total time of the communication time of the target node and the communication time of the neighboring nodes for each of the plurality of nodes, with each of the plurality of nodes being the target node, A route control unit controls the upstream route for transmitting data from each of the plurality of nodes to the aggregation device based on the total time calculated by the time calculation unit. Equipped with, A communication system that controls the uplink route for transmitting data from a selected node to an aggregation device by selecting a node whose total time is equal to or greater than a threshold as a selected node, and setting the destination for transmitting data from the selected node to the aggregation device to the adjacent node, if there is a spare node whose total time is less than a threshold, as an adjacent node to the selected node.

2. A communication system comprising an aggregation device and multiple nodes, Each of the aforementioned plurality of nodes is installed to be able to communicate directly with one or more other adjacent nodes, and transmits data to the aggregation device directly or via the adjacent nodes. A time calculation unit that calculates the total time of the communication time of the target node and the communication time of the neighboring nodes for each of the plurality of nodes, with each of the plurality of nodes being the target node, A route control unit controls the upstream route for transmitting data from each of the multiple nodes to the aggregation device so that the total time for each of the multiple nodes calculated by the time calculation unit is averaged. A communication system equipped with [the following features].

3. A communication system comprising a plurality of nodes and a plurality of aggregation devices that transmit data received from the plurality of nodes to a higher-level device, Each of the aforementioned nodes is installed to communicate directly with one or more other adjacent nodes, and transmits data directly or via the adjacent nodes to one of the aforementioned aggregation devices. A time calculation unit that calculates the total time of the communication time of each of the plurality of nodes as a target node and the communication time of the adjacent nodes for each of the plurality of nodes as a target node, and calculates the total time of the communication time of each of the plurality of aggregation devices as a target aggregation device and the communication time of nodes installed to communicate directly with the target aggregation device, A route control unit that controls the upstream route for transmitting data from each of the multiple nodes to one of the multiple aggregation devices, based on the total time calculated for the multiple nodes by the time calculation unit and the total time calculated for the multiple aggregation devices, wherein if there is an excess device which is an aggregation device whose total time is greater than or equal to a threshold, the route control unit controls the upstream route by changing the destination of the nodes on the upstream route that transmit data to the excess device. A communication system equipped with [the following features].

4. The route control unit selects nodes whose total time is equal to or greater than a threshold from among the nodes that transmit data to the excess device, and if there are adjacent nodes with a total time less than a threshold that are adjacent to the selected node, it sets the destination for data transmission from the selected node to the aggregation device to the idle node, thereby controlling the upstream route for transmitting data from the selected node to the aggregation device. The communication system according to claim 3.

5. A communication system comprising a plurality of nodes and a plurality of aggregation devices that transmit data received from the plurality of nodes to a higher-level device, Each of the aforementioned nodes is installed to communicate directly with one or more other adjacent nodes, and transmits data directly or via the adjacent nodes to one of the aforementioned aggregation devices. A time calculation unit that calculates the total time of the communication time of each of the plurality of nodes as a target node and the communication time of the adjacent nodes for each of the plurality of nodes as a target node, and calculates the total time of the communication time of each of the plurality of aggregation devices as a target aggregation device and the communication time of nodes installed to communicate directly with the target aggregation device, A route control unit that controls an uplink route for transmitting data from each of the multiple nodes to one of the multiple aggregation devices, based on the total time calculated for the multiple nodes by the time calculation unit and the total time calculated for the multiple aggregation devices, wherein the route control unit controls the uplink route so that the total time for each of the multiple aggregation devices and each of the multiple nodes is averaged. A communication system equipped with [the following features].

6. A communication system comprising an aggregation device and a plurality of nodes, wherein each of the plurality of nodes is installed to be able to communicate directly with one or more other nodes which are adjacent nodes, and transmits data to the aggregation device directly or via the adjacent nodes, wherein the communication system comprises a central device that controls the uplink path for transmitting data from each of the plurality of nodes to the aggregation device, A time calculation unit that calculates the total time of the communication time of the target node and the communication time of the neighboring nodes for each of the plurality of nodes, with each of the plurality of nodes being the target node, Based on the total time calculated by the time calculation unit, a route control unit controls the uphill route. A central device equipped with this system.

7. A communication system comprising an aggregation device and a plurality of nodes, wherein each of the plurality of nodes is installed to be able to communicate directly with one or more other nodes which are adjacent nodes, and transmits data to the aggregation device directly or via the adjacent nodes, wherein the method controls the uplink path for transmitting data from each of the plurality of nodes to the aggregation device. Each of the plurality of nodes is treated as a target node, and the total time of the communication time of the target node and the communication time of the neighboring nodes for the target node is calculated. A path control method for controlling the upstream path for transmitting data from a selected node to an aggregation device, by selecting a node whose total time is equal to or greater than a threshold as a selected node, and if there is a spare node whose total time is less than a threshold as an adjacent node to the selected node, setting the destination for transmitting data from the selected node to the aggregation device to the spare node.

8. A communication system comprising an aggregation device and a plurality of nodes, wherein each of the plurality of nodes is installed to be able to communicate directly with one or more other nodes which are adjacent nodes, and transmits data to the aggregation device directly or via the adjacent nodes, wherein the method controls the uplink path for transmitting data from each of the plurality of nodes to the aggregation device. Each of the plurality of nodes is treated as a target node, and the total time of the communication time of the target node and the communication time of the neighboring nodes for the target node is calculated. A route control method for controlling the uplink route such that the total time for each of the plurality of nodes is averaged.

9. A communication system comprising a plurality of nodes and a plurality of aggregation devices that transmit data received from the plurality of nodes to a higher-level device, wherein each of the plurality of nodes is installed to be able to communicate directly with one or more other nodes which are adjacent nodes, and transmits data to any of the plurality of aggregation devices directly or via the adjacent nodes, a routing control method for controlling the uplink route for transmitting data from each of the plurality of nodes to any of the plurality of aggregation devices, Each of the plurality of nodes is treated as a target node, and the total time of the communication time of the target node and the communication time of the adjacent nodes for the target node is calculated. Each of the plurality of aggregation devices is treated as a target aggregation device, and the total time of the communication time of the target aggregation device and the communication time of the nodes installed to communicate directly with the target aggregation device is calculated. Based on the total time calculated for the plurality of nodes and the total time calculated for the plurality of aggregation devices, the upstream path is controlled. A route control method for controlling the upstream route by changing the destination of nodes located on the upstream route that transmit data to the exceeding device, when there is an exceeding device which is an aggregation device whose total time exceeds a threshold.

10. A communication system comprising a plurality of nodes and a plurality of aggregation devices that transmit data received from the plurality of nodes to a higher-level device, wherein each of the plurality of nodes is installed to be able to communicate directly with one or more other nodes which are adjacent nodes, and transmits data to any of the plurality of aggregation devices directly or via the adjacent nodes, a method for controlling the uplink path for transmitting data from each of the plurality of nodes to any of the plurality of aggregation devices, Each of the plurality of nodes is treated as a target node, and the total time of the communication time of the target node and the communication time of the adjacent nodes for the target node is calculated. Each of the plurality of aggregation devices is treated as a target aggregation device, and the total time of the communication time of the target aggregation device and the communication time of the nodes installed to communicate directly with the target aggregation device is calculated. Based on the total time calculated for the plurality of nodes and the total time calculated for the plurality of aggregation devices, the upstream path is controlled. A route control method for controlling the upstream route such that the total time for each of the plurality of aggregation devices and each of the plurality of nodes is averaged.

11. A communication system comprising an aggregation device and a plurality of nodes, wherein each of the plurality of nodes is installed to be able to communicate directly with one or more other nodes which are adjacent nodes, and transmits data to the aggregation device directly or via the adjacent nodes, wherein the communication system is provided with a routing control program that controls the uplink path for transmitting data from each of the plurality of nodes to the aggregation device. A time calculation process that calculates the total time of the communication time of the target node and the communication time of the neighboring nodes for each of the plurality of nodes, with each of the aforementioned nodes as the target node, Based on the total time calculated by the aforementioned time calculation process, a route control process is performed to control the uphill route. Have the computer run it, A route control program that controls the uplink route for transmitting data from the selected node to the aggregation device by selecting a node whose total time is equal to or greater than a threshold as a selected node in the route control process, and setting the destination for transmitting data from the selected node to the aggregation device to the idle node if there is an idle node whose total time is less than a threshold as an adjacent node to the selected node.

12. A communication system comprising an aggregation device and a plurality of nodes, wherein each of the plurality of nodes is installed to be able to communicate directly with one or more other nodes which are adjacent nodes, and transmits data to the aggregation device directly or via the adjacent nodes, wherein the communication system is provided with a routing control program that controls the uplink path for transmitting data from each of the plurality of nodes to the aggregation device. A time calculation process that calculates the total time of the communication time of the target node and the communication time of the neighboring nodes for each of the plurality of nodes, with each of the aforementioned nodes as the target node, Route control processing controls the uphill path such that the total time for each of the plurality of nodes calculated by the time calculation process is averaged. A routing program that causes a computer to execute a routing command.

13. A communication system comprising a plurality of nodes and a plurality of aggregation devices that transmit data received from the plurality of nodes to a higher-level device, wherein each of the plurality of nodes is installed to be able to communicate directly with one or more other nodes which are adjacent nodes, and transmits data to any of the plurality of aggregation devices directly or via the adjacent nodes, a routing control program that controls the uplink route for transmitting data from each of the plurality of nodes to any of the plurality of aggregation devices, A time calculation process that calculates the total time of the communication time of each of the plurality of nodes as a target node and the communication time of the adjacent nodes for each of the plurality of nodes as a target node, and calculates the total time of the communication time of each of the plurality of aggregation devices as a target aggregation device and the communication time of the nodes installed to communicate directly with the target aggregation device, A route control process that controls the upstream route based on the total time calculated for the plurality of nodes by the time calculation process and the total time calculated for the plurality of aggregation devices, wherein if there is an excess device which is an aggregation device whose total time is greater than or equal to a threshold, the route control process controls the upstream route by changing the destination of the node located on the upstream route that transmits data to the excess device. A routing program that causes a computer to execute a routing command.

14. A communication system comprising a plurality of nodes and a plurality of aggregation devices that transmit data received from the plurality of nodes to a higher-level device, wherein each of the plurality of nodes is installed to be able to communicate directly with one or more other nodes which are adjacent nodes, and transmits data to any of the plurality of aggregation devices directly or via the adjacent nodes, a routing control program that controls the uplink route for transmitting data from each of the plurality of nodes to any of the plurality of aggregation devices, A time calculation process that calculates the total time of the communication time of each of the plurality of nodes as a target node and the communication time of the adjacent nodes for each of the plurality of nodes as a target node, and calculates the total time of the communication time of each of the plurality of aggregation devices as a target aggregation device and the communication time of the nodes installed to communicate directly with the target aggregation device, A route control process for controlling the upstream route based on the calculated total time calculated for the plurality of nodes by the time calculation process and the calculated total time calculated for the plurality of aggregation devices, wherein the route control process controls the upstream route such that the total time for each of the plurality of aggregation devices and each of the plurality of nodes is averaged. A routing program that causes a computer to execute a routing command.