Smart meter communication system, network management device, smart meter communication program, redundancy program, smart meter communication method, and redundancy method

Abstract

Conventionally, there has been the problem that it takes time to transmit requested information to an application and reliability of communication is low. A smart meter communication system according to the present disclosure comprises: an information acquisition unit that has a cellular communication function and a multi-hop communication function, and that acquires topology information, which is information that indicates a connection relationship for communication among a plurality of smart meters including a plurality of hybrid smart meters capable of switching between on and off of the cellular communication function and that changes when the cellular communication function of the one or more hybrid smart meters is turned on and when the cellular communication function is turned off, and communication information which is information that indicates the communication quality among the plurality of smart meters and changes in conjunction with changes in the topology information; a candidate selection unit that uses the communication information and the topology information to select a candidate for the hybrid smart meter that turns on the cellular communication function; and a control signal transmission unit that transmits a control signal for turning on the cellular communication function of the selected hybrid smart meter.

Description

Smart meter communication system, network management device, smart meter communication program, redundancy program, smart meter communication method, and redundancy method

[0001] The present disclosure relates to a smart meter communication system, a network management device, a smart meter communication program, a redundancy program, a smart meter communication method, and a redundancy method.

[0002] In a conventional smart meter communication system, a determination device includes a communication method switching unit that controls the communication method of a dual communication smart meter to switch between a cellular method and an RF (Radio Frequency) mesh network method. The conventional determination device switches the communication method when the communication connection quality does not satisfy a reference value. Examples of cases where the communication connection quality does not satisfy the reference value include when a communication delay occurs or when communication is interrupted.

[0003] Japanese Patent Application Laid-Open No. 2020-80471

[0004] The determination device of Patent Document 1 switched communication methods only when a communication delay occurred or communication was interrupted, which resulted in a problem of low communication reliability as it took a long time to send information requested by an application to the application.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a smart meter communication system that can achieve highly reliable communication without switching communication in order to send information requested by an application to the application within a certain period of time.

[0006] The smart meter communication system of the present disclosure includes a plurality of hybrid smart meters having two types of communication functions, a cellular communication function and a multi-hop communication function, and capable of switching the cellular communication function on and off; an information acquisition unit that acquires information indicating the communication connection relationship between the plurality of smart meters including the hybrid smart meters, which is topology information that changes when the cellular communication function of one or more hybrid smart meters is turned on and off, and information indicating the communication quality between the plurality of smart meters, and which changes as the topology information changes; a candidate selection unit that uses the acquired communication information and topology information to select a candidate hybrid smart meter for which the cellular communication function will be turned on; and a control signal transmission unit that transmits a control signal to turn on the cellular communication function of the hybrid smart meter selected by the candidate selection unit.

[0007] The smart meter communication system of the present disclosure includes a candidate selection unit that uses the topology information and communication information acquired by the information acquisition unit to select a candidate hybrid smart meter for which cellular communication is to be turned on, and a control signal transmission unit that transmits a control signal to the selected candidate hybrid smart meter for turning on the cellular communication function. Therefore, the smart meter communication system uses topology information that indicates the communication connection relationship and communication information that is information that indicates the communication quality corresponding to the topology information to select a candidate hybrid smart meter for which cellular communication is to be turned on, and transmits a control signal to turn on the cellular communication function of the selected candidate hybrid smart meter, thereby achieving highly reliable communication.

[0008] 1 is a diagram illustrating an example of the configuration of a smart meter communication system according to a first embodiment. FIG. 2 is a diagram illustrating the configuration of a network management device according to the first embodiment. FIG. 3 is a diagram illustrating the configuration of a hybrid smart meter according to the first embodiment. FIG. 4 is a diagram illustrating the configuration of a cellular smart meter according to the first embodiment. FIG. 5 is a diagram illustrating the configuration of a multi-hop smart meter according to the first embodiment. FIG. 6 is a hardware configuration diagram illustrating a hardware configuration according to the first embodiment. FIG. 7 is a flowchart illustrating prerequisite operation 0 for a network construction by a network management device according to the first embodiment. FIG. 8 is a flowchart illustrating operation 1 for a network construction by a network management device according to the first embodiment. FIG. 9 is a flowchart illustrating operation 2 for a network construction by a network management device according to the first embodiment. FIG. 10 is a flowchart illustrating operation 3 for a network construction by a network management device according to the first embodiment. FIG. 11 is a flowchart illustrating operation 4 for a network construction by a network management device according to the first embodiment. FIG. 12 is a flowchart illustrating operation of redundancy determination of a parent node performed by a redundancy determination unit according to the first embodiment. FIG. 13 is a flowchart illustrating operation of redundancy determination of an accommodating node performed by a redundancy determination unit according to the first embodiment. FIG. 14 is a flowchart illustrating operation 5 for a network construction by a network management device according to a modified example.

[0009] Hereinafter, embodiments will be described with reference to the drawings. Common or corresponding elements in each drawing are designated by the same reference numerals, and descriptions thereof will be simplified or omitted. Furthermore, the configurations shown in the following embodiments are examples of the technical ideas of the present disclosure, and may be combined with other known technologies, or multiple technical ideas described in the present disclosure may be combined. Furthermore, it is also possible to omit or modify part of the configuration without departing from the gist of the present disclosure.

[0010] Embodiment 1. A smart meter communication system is a system in which smart meters perform various communications, such as environmental value trading and electricity waveform data collection, in addition to conventional automatic meter reading. Smart meter communication systems are expected to handle larger data volumes and have more diverse QoS (Quality of Service) requirements than conventional systems. To build a system that can accommodate various QoS requirements, all smart meters in the system must be equipped with cellular communication capabilities. However, if all smart meters are replaced with smart meters equipped with cellular communication capabilities, line usage fees will be incurred when the smart meters perform cellular communication, resulting in increased usage fees for users. Therefore, by introducing a hybrid smart meter that can use both multi-hop communication, which is also used in conventional smart meter communication systems, and cellular communication, the smart meter communication system can reduce communication costs while also incorporating and using multi-hop smart meters that can only use multi-hop communication. For this reason, building a system using multi-hop smart meters, cellular smart meters, and hybrid smart meters is attracting attention in next-generation smart meter communication systems. In this embodiment, a smart meter communication system constructed using a multi-hop smart meter, a cellular smart meter, and a hybrid smart meter will be described.

[0011] 1 is a diagram showing an example of the configuration of a smart meter communication system 1 according to embodiment 1. The smart meter communication system 1 is composed of a network management device 2, a data collection device 3, a cellular base station 4, a hybrid smart meter 5, a cellular smart meter 6, and a multi-hop smart meter 7. Hereinafter, the hybrid smart meter 5, the cellular smart meter 6, and the multi-hop smart meter 7 may be collectively referred to as smart meters. In the figure, the hybrid smart meter 5 is represented as an HSM, the cellular smart meter 6 as an SSM, the multi-hop smart meter 7 as an MHSM, and the smart meter as an SM.

[0012] The network management device 2 is a device that manages the configuration of information transmission paths in the smart meter communication system 1. In other words, the network management device 2 is a device that constructs a network in the smart meter communication system 1. Fig. 2 is a configuration diagram showing the configuration of the network management device 2 according to the first embodiment. The network management device 2 includes an information acquisition unit 21, a candidate selection unit 22, a determination unit 23, and a control signal transmission unit 24. The network management device 2 controls the entire smart meter system, such as switching the power supply and software updates to the smart meters, and transmitting control signals that switch the multi-hop communication function and cellular communication function on and off.

[0013] The information acquisition unit 21 acquires topology information, carrier information, and communication information corresponding to the communication connection relationship indicated by the topology information.

[0014] The topology information is information indicating the communication connection relationship between the hybrid smart meters 5 and the multi-hop smart meters 7 that constitute the smart meter communication system 1. The topology information indicates the communication connection relationship that changes depending on whether the cellular communication function of the hybrid smart meter 5 is on or off. The communication connection relationship here refers to a computer network. The topology information can be obtained from information transmitted from each smart meter. Specifically, when each smart meter transmits information, the hybrid smart meter 5 or the multi-hop smart meter 7, which relays multi-hop communication on each transmission path, adds the MAC (Media Access Control) address and RSSI (Received Signal Strength Indicator) of the parent node to the header of the information transmitted from another smart meter, and then transmits the information to the parent node via multi-hop communication. Therefore, it is possible to obtain the topology information from the information transmitted in this manner.

[0015] In addition, the parent node refers to the next destination, the hybrid smart meter 5 or the multi-hop smart meter 7, in the network that transmits information from each smart meter to the cellular base station 4, and here refers to the destination to which information is transmitted directly without involving other smart meters or devices.

[0016] The topology information includes, for example, the number of subordinate terminals. The number of subordinate terminals can be obtained, for example, by counting the number of MAC addresses of added parent nodes or the number of times the MAC address of an added parent node has been rewritten. Here, the term "subordinate terminals" refers to other hybrid smart meters 5 or multi-hop smart meters 7 that transmit information to a given hybrid smart meter 5 or multi-hop smart meter 7. The term "number of subordinate terminals" refers to the number of subordinate terminals, for each smart meter, that transmit information to that smart meter. Other examples of topology information include, but are not limited to, the transmission path from the smart meter to the accommodation node, the smart meter's identification information, information indicating whether the available communication method is multi-hop communication or cellular communication, and the smart meter's location information. Here, the accommodation node refers to a hybrid smart meter 5 that directly communicates with a cellular base station 4 in the smart meter communication system 1 and transmits information to the cellular base station 4. In this embodiment, an example using the number of subordinate terminals included in the topology information will be described.

[0017] The carrier information indicates which mobile carrier has a contract with each hybrid smart meter 5. In other words, the carrier information indicates which cellular base station 4 and which hybrid smart meter 5 are capable of cellular communication when the network management device 2 constructs a network.

[0018] The communication information indicates at least one of the communication quality and signal strength between multiple smart meters, and the content acquired varies depending on the situation. Furthermore, since the communication information corresponds to the communication connection relationship indicated by the topology information, the information changes from moment to moment as the topology information changes. Examples of information indicating communication quality include the packet error rate, the number of channel access errors, the number of accommodated nodes, the number of local repairs, and the number of MAC errors.

[0019] Here, the packet error rate means the probability of an error occurring in packet transmission when a packet, which is a transmission unit obtained by dividing information transmitted by a smart meter into small pieces at a fixed length, is transmitted. Also, the number of channel access errors means the number of times an error occurs when the hybrid smart meter 5 and the multi-hop smart meter 7 access a channel, which is a radio frequency band assigned to the hybrid smart meter 5 and the multi-hop smart meter 7, to transmit and receive data in the network.

[0020] The number of accommodated nodes means the number of multi-hop smart meters 7 that transmit information to the accommodated node. Here, a method by which other smart meters obtain information for identifying the accommodated node will be described. When the state of a hybrid smart meter 5 performing multi-hop communication is changed to an accommodated node that communicates with a cellular base station 4, the ID indicating the state of the hybrid smart meter 5 is changed. When the ID indicating the state of the hybrid smart meter 5 is changed or at any time, the accommodated node, which is the hybrid smart meter 5 whose state has changed, transmits information including at least either its own ID or address, and other smart meters can obtain this transmitted information for identifying the accommodated node.

[0021] Furthermore, the hybrid smart meter 5 or multi-hop smart meter 7 to which information is transmitted is referred to as the upstream side, and the hybrid smart meter 5 or multi-hop smart meter 7 to which information is transmitted is referred to as the downstream side. In other words, on the transmission path, the accommodation node is on the upstream side, and the hybrid smart meter 5 or multi-hop smart meter 7 that transmits information toward the accommodation node is on the downstream side. On the transmission path, each hybrid smart meter 5 or each multi-hop smart meter 7 on the downstream side transmits information toward the accommodation node on the upstream side.

[0022] The number of local repairs means the number of hybrid smart meters 5 or multi-hop smart meters 7 in which information is stored. For example, if the number of local repairs is 1, the number of hybrid smart meters 5 or multi-hop smart meters 7 in which information is stored is one. If the number of local repairs is 2, the number of hybrid smart meters 5 or multi-hop smart meters 7 in which information is stored is two, and even if one of the hybrid smart meters 5 or multi-hop smart meters 7 in which information is stored breaks down, it is possible to transmit information from the other hybrid smart meter 5 or multi-hop smart meter 7.

[0023] The number of MAC errors refers to the number of errors that occur when connecting to a network using MAC address control.

[0024] The information indicating the signal strength is, for example, RSSI or RSRP (Reference Signal Received Power). Note that, instead of the information indicating the signal strength, RSRQ (Reference Signal Received Quality) or SINR (Signal-to-Interference-plus-Noise Ratio) may be used. Note that in this embodiment, an example using RSRP will be described.

[0025] The candidate selection unit 22 selects candidates for the hybrid smart meters 5 for which the cellular communication function is to be turned on, using the topology information, carrier information, and communication information acquired by the information acquisition unit 21. Specifically, the candidate selection unit 22 selects hybrid smart meters 5 for which the communication quality or signal strength of multi-hop communication is equal to or less than a threshold, as candidate hybrid smart meters 5 for which the cellular communication function is to be turned on.

[0026] When the cellular communication function of the hybrid smart meter 5 that is a candidate selected by the candidate selection unit 22 is turned on, the hybrid smart meter 5 with the cellular communication function turned on transmits RSRP. When the signal strength in the cellular communication of the hybrid smart meter 5 with the cellular communication function turned on is equal to or less than the threshold, the determination unit 23 determines to turn off the cellular communication function of the hybrid smart meter 5 again. When the signal strength is equal to or greater than the threshold, the determination unit 23 determines to continue the cellular communication function turned on.

[0027] The control signal transmitter 24 transmits a control signal to turn on the cellular communication function of the hybrid smart meter 5 selected as a candidate for turning on the cellular communication function. Furthermore, if the determination unit 23 determines that the cellular communication function of the hybrid smart meter 5 should be turned off, the control signal transmitter 24 transmits a control signal to turn off the cellular communication function of the hybrid smart meter 5. If the determination unit 23 determines that the cellular communication function should be kept on, the control signal transmitter 24 transmits a control signal to keep the cellular communication function of the hybrid smart meter 5 on. Note that if the cellular communication function of the hybrid smart meter 5 is to be kept on, it is also possible not to transmit a control signal. The control signal transmitted by the control signal transmitter 24 may be transmitted directly to the hybrid smart meter 5, or may be transmitted to the hybrid smart meter 5 via the data collection device 3 or the cellular base station 4.

[0028] The data collection device 3 tallyes application data collected from the smart meters. The data collection device 3 exchanges information between the information acquisition unit 21 of the network management device 2 and the cellular base station 4. The data collection device 3 is also a transit point when a control signal is transmitted from the control signal transmission unit 24 of the network management device 2 to the hybrid smart meter 5 via the cellular base station 4. The data collection device 3 exchanges information or control signals with the information acquisition unit 21 of the network management device 2, the control signal transmission unit 24 of the network management device 2, and the cellular base station 4 via wireless communication.

[0029] The cellular base station 4 authenticates the SIM (Subscriber Identity Module) of the smart meter. Here, the SIM is an IC card that is inserted into the hybrid smart meter 5 and the cellular smart meter 6 and records user identification information and the like. By performing this authentication, it is possible to determine which smart meter transmitted which data. The cellular base station 4 communicates wirelessly with the data collection device 3. The cellular base station 4 also transmits to the hybrid smart meter 5 a control signal that is transmitted by the control signal transmission unit 24 of the network management device 2 and received via the data collection device 3.

[0030] FIG. 3 is a configuration diagram showing the configuration of the hybrid smart meter 5. The hybrid smart meter 5 will be described using FIG. 3. The hybrid smart meter 5 has means for executing two types of communication methods: multi-hop communication and cellular communication. The hybrid smart meter 5 includes a metering unit 51, a multi-hop communication unit 52, a multi-hop communication management unit 53, a redundancy determination unit 54, a redundant path control unit 55, a multi-hop path management unit 56, a cellular communication unit 57, a cellular communication management unit 58, and a cellular path management unit 59. The hybrid smart meter 5 communicates wirelessly with other hybrid smart meters 5 or multi-hop smart meters 7. The hybrid smart meter 5 also communicates wirelessly with a cellular base station 4. The multi-hop communication may be a communication method using the 920 MHz band, or may be another communication method such as D2D (Device to Device), which is a terminal-to-terminal communication technology, or communication using Wi-Fi.

[0031] The metering unit 51 acquires measurement data from at least one of a gas meter, an electricity meter, and a water meter. In addition to the measurement data, the metering unit 51 may also acquire other information such as environmental value trading and power waveform data.

[0032] The multi-hop communication unit 52 receives communication information of other hybrid smart meters 5 from the network management device 2 or the data collection device 3 via the cellular base station 4, and transmits the information to the multi-hop communication management unit 53. The multi-hop communication unit 52 also receives measurement data hopped from the metering unit 51 or from other hybrid smart meters 5 or multi-hop smart meters 7. The multi-hop communication unit 52 transmits information via a transmission route instructed by the multi-hop route management unit 56, which will be described later. The multi-hop communication unit 52 may transmit measurement data to the cellular base station 4 via other hybrid smart meters 5.

[0033] The multi-hop communication management unit 53 transmits information to the multi-hop communication unit 52. The multi-hop communication management unit 53 also receives communication information of other smart meters from the multi-hop communication unit 52 and transmits it to the redundancy determination unit .

[0034] The redundancy determination unit 54 receives communication information from the multi-hop communication unit 52 and receives information indicating whether the cellular communication function is on or off from the cellular communication management unit 58 (described later). When receiving information indicating that the cellular communication function is off, the redundancy determination unit 54 uses the communication information to determine whether or not to implement redundancy. Here, redundancy means providing two or more transmission paths in the smart meter communication system 1, particularly between the hybrid smart meters 5 and the hybrid smart meters 5, between the hybrid smart meters 5 and the multi-hop smart meters 7, and between the multi-hop smart meters 7 and the multi-hop smart meters 7. In other words, when redundancy is not implemented, there is one transmission path, and when redundancy is implemented, there are two or more transmission paths. The redundancy determination unit 54 transmits the determination result regarding whether or not to implement redundancy to the redundant path control unit 55. The determination result is, for example, the result of the redundancy determination unit 54's determination as to whether or not to implement redundancy.

[0035] The redundant path control unit 55 receives the determination result as to whether or not to implement redundancy from the redundancy determination unit 54, and receives transmission path information indicating the transmission path from the hybrid smart meter 5 to the accommodation node that was used before the redundancy determination unit 54 made its determination from the multi-hop path management unit 56 and the cellular path management unit 59, which will be described later. Note that the hybrid smart meter 5 that was used before the redundancy determination unit 54 made its determination here is the hybrid smart meter 5 that is making the determination as to whether or not to implement redundancy.

[0036] When the redundant path control unit 55 receives the determination result that redundancy will be implemented from the redundancy determination unit 54, it uses the transmission path information to select a transmission path from the hybrid smart meter 5 that is determining whether or not to newly implement redundancy to the parent node and determine the number of transmission paths. Note that the hybrid smart meter 5 that is determining whether or not to newly implement redundancy here refers to the hybrid smart meter 5 that is determining whether or not to implement redundancy. Here, the transmission path information includes, for example, a path identification ID (DODAG ID) or destination information of the smart meter that will be the parent node.

[0037] After selecting a transmission route and determining the number of transmission routes, the redundant route control unit 55 transmits a control instruction to the multihop route management unit 56. The control instruction includes information indicating the selected transmission route and the number of determined transmission routes, and indicates which transmission route to use when transmitting information using the multihop communication function.

[0038] The multihop route management unit 56 transmits the above-mentioned transmission route information to the redundant route control unit 55. Thereafter, the multihop route management unit 56 uses the control instruction received from the redundant route control unit 55 to specify a transmission route to the multihop communication unit 52.

[0039] The cellular communication unit 57 receives the control signal transmitted by the control signal transmission unit 24 via the data collection device 3 and the cellular base station 4. The cellular communication unit 57 transmits the data acquired by the metering unit 51 and the information hopped from other smart meters to the identified cellular base station 4. The cellular base station 4 is identified using information about the cellular base station 4 identified by the cellular route management unit 59, which will be described later. Information is transmitted by wireless communication between the cellular communication unit 57 and the cellular base station 4. When cellular communication is used, information is transmitted in a batch, and information is not transmitted using both multi-hop communication and cellular communication of the same hybrid smart meter 5. When the cellular communication function is off, information is transmitted via multi-hop communication, and when the cellular communication function is on, information is transmitted via cellular communication.

[0040] When cellular communication management unit 58 receives a control signal to turn on the cellular communication function from control signal transmission unit 24, it turns on the cellular communication function if the cellular communication function is off. Also, when cellular communication management unit 58 receives a control signal to turn off the cellular communication function from control signal transmission unit 24, it turns off the cellular communication function if the cellular communication function is on. Also, cellular communication management unit 58 transmits information indicating whether the cellular communication function is on or off to redundancy determination unit 54 when the cellular communication function is switched from on to off or from off to on.

[0041] The cellular route management unit 59 transmits the above-mentioned transmission route information to the redundant route control unit 55. The cellular route management unit 59 uses the carrier information to identify a cellular base station 4 with which communication is possible because it is managed by a contracted mobile operator. After identifying the cellular base station 4, the cellular route management unit 59 transmits information about the identified cellular base station 4 to the cellular communication unit 57. Note that the information about the identified cellular base station 4 is, for example, location information or identification information of the cellular base station 4.

[0042] 4 is a configuration diagram showing the configuration of the cellular smart meter 6. The cellular smart meter 6 includes a metering unit 61, a cellular communication unit 67, a cellular communication management unit 68, and a cellular route management unit 69. Note that the metering unit 61, the cellular communication unit 67, the cellular communication management unit 68, and the cellular route management unit 69 of the cellular smart meter 6 have the same functions as the metering unit 51, the cellular communication unit 57, the cellular communication management unit 58, and the cellular route management unit 59 of the hybrid smart meter 5, respectively, and therefore detailed description thereof will be omitted.

[0043] 5 is a configuration diagram showing the configuration of the multi-hop smart meter 7. The multi-hop smart meter 7 includes a metering unit 71, a multi-hop communication unit 72, a multi-hop communication management unit 73, a redundancy determination unit 74, a redundant path control unit 75, and a multi-hop path management unit 76. The metering unit 71, the multi-hop communication unit 72, the multi-hop communication management unit 73, the redundancy determination unit 74, the redundant path control unit 75, and the multi-hop path management unit 76 of the multi-hop smart meter 7 have the same functions as the metering unit 51, the multi-hop communication unit 52, the multi-hop communication management unit 53, the redundancy determination unit 54, the redundant path control unit 55, and the multi-hop path management unit 56 of the hybrid smart meter 5, respectively, and therefore detailed description thereof will be omitted.

[0044] Next, we will explain the hardware configuration of the network management device 2. Fig. 6 is a hardware configuration diagram showing the hardware configuration of the network management device 2. The network management device 2 is made up of a processing unit 8, a storage device 9, an input device 10, an auxiliary storage device 11, an output device 12, and a signal line 13.

[0045] The processing performed by the network management device 2 can be realized by, for example, the arithmetic unit 8. The arithmetic unit 8 realizes the functions of the network management device 2 by reading necessary programs from the auxiliary storage device 11 and executing the processes. The arithmetic unit 8 is, for example, a processor, and the processor is an IC (Integrated Circuit) that performs arithmetic processing. Specific examples of a processor are a CPU (Central Processing Unit), a DSP (Digital Signal Processor), and a GPU (Graphics Processing Unit).

[0046] The storage device 9 is the main storage device of the network management device 2. The storage device 9 temporarily stores the results of the calculation processing performed by the arithmetic device 8. For example, the storage device 9 is a RAM (Random Access Memory).

[0047] The input device 10 inputs the measurement data and communication information of each smart meter transmitted from the data collection device 3 to the network management device 2. The input device 10 is an input interface of the network management device 2.

[0048] The auxiliary storage device 11 is an auxiliary storage device of the network management device 2. For example, the auxiliary storage device 11 stores topology information, programs necessary for the operation of the network management device 2, selection lists 0 to 3 (described later), etc. For example, the auxiliary storage device 11 is a read-only memory (ROM), a hard disk drive (HDD), or a solid state drive (SSD).

[0049] The output device 12 outputs output data to the data collection device 3. The output device 12 is an output interface of the network management device 2.

[0050] The signal line 13 is a transmission path for transmitting and receiving data between the components shown in FIG.

[0051] Next, a description will be given of the hardware configuration of the hybrid smart meter 5. The hybrid smart meter 5 includes, as its hardware configuration, a calculation unit, a storage unit, an input device, an auxiliary storage unit, an output device, and a signal line (not shown). Note that specific examples of each component are the same as those of the network management device 2 described above, and therefore, description thereof will be omitted.

[0052] The processing performed by the hybrid smart meter 5 can be executed, for example, by an arithmetic device (not shown). The storage device (not shown) of the hybrid smart meter 5 is the main storage device of the hybrid smart meter 5. The storage device temporarily stores the results of calculation processing performed by the arithmetic device. The input device (not shown) inputs information transmitted from the cellular base station 4, other hybrid smart meters 5, and the multi-hop smart meter 7 to the hybrid smart meter 5. The input device is an input interface of the hybrid smart meter 5. The auxiliary storage device (not shown) is the auxiliary storage device of the hybrid smart meter 5. For example, the auxiliary storage device stores programs necessary for the operation of the hybrid smart meter 5, such as redundancy programs. The auxiliary storage device also stores information necessary for the operation of the hybrid smart meter 5, such as carrier information. The output device (not shown) outputs output data from the hybrid smart meter 5. The output device is an output interface of the hybrid smart meter 5. The signal lines (not shown) are transmission paths for transmitting and receiving data between the hardware components of the hybrid smart meter 5.

[0053] Next, the network construction operation performed by the network management device 2 and the redundancy determination operation of the hybrid smart meter 5 whose cellular communication function is off will be described. Once the network management device 2 constructs a network and secures a transmission path, the hybrid smart meter 5 determines a transmission path within the range of the secured transmission path. The determination of the transmission path includes whether or not to implement redundancy. Figures 7 to 11 are flowcharts showing the network construction operation performed by the network management device 2. Figures 12 and 13 are flowcharts showing the redundancy determination operation of the hybrid smart meter 5.

[0054] First, the network construction operation performed by the network management device 2 will be described with reference to Fig. 7 to Fig. 11. Fig. 7 to Fig. 11 explain the operation performed by the network management device 2 when constructing a network, dividing it into prerequisite operation 0 and operations 1 to 4. Note that, as a premise for performing the network construction operation, it is assumed that the same hybrid smart meter 5 will not be determined in one control cycle in which prerequisite operation 0 and operations 1 to 4 are performed.

[0055] Prerequisite operation 0 will be described with reference to FIG. 7 . The candidate selection unit 22 periodically executes the operation for prerequisite operation 0. The candidate selection unit 22 may be configured to start the operation of prerequisite operation 0 every time a period of time, for example, approximately 30 minutes to 1 hour, has elapsed, but the length of the period is not limited to this. Prerequisite operation 0 includes steps S1 to S4. Prerequisite operation 0 will also be described with reference to FIG. 7 . In prerequisite operation 0 of FIG. 7 , when the candidate selection unit 22 starts its operation, the process proceeds to step S1. In step S1, the candidate selection unit 22 selects an undetermined hybrid smart meter 5 from all hybrid smart meters 5 to be determined. Note that the hybrid smart meter 5 to be determined is not limited to all hybrid smart meters 5 that constitute the network, and may be arbitrarily determined. When the candidate selection unit 22 selects an undetermined hybrid smart meter 5, the process proceeds to step S2.

[0056] In step S2, the candidate selection unit 22 determines whether the cellular communication function of the selected undetermined hybrid smart meter 5 is on or off. If the cellular communication function of the selected undetermined hybrid smart meter 5 is on, the process returns to step S1. Here, when the process returns to step S1, for the hybrid smart meter 5 determined in step S2 to have its cellular communication function on, the fact that the determination has been made is stored, for example, in the storage device 9. On the other hand, if the cellular communication function of the selected undetermined hybrid smart meter 5 is off, the process proceeds to step S3.

[0057] In step S3, the candidate selection unit 22 registers the hybrid smart meter 5 selected in step S1, whose cellular communication function is not on, in the selection preparation list 0. When the hybrid smart meter 5 selected in step S1, whose cellular communication function is not on, is registered in the selection preparation list 0, the process proceeds to step S4.

[0058] In step S4, the candidate selection unit 22 determines whether or not there is an undetermined hybrid smart meter 5 among all the hybrid smart meters 5 to be determined. If there is an undetermined hybrid smart meter 5, the process returns to step S1. Here, when the process returns to step S1, for the hybrid smart meter 5 determined in step S2 to have its cellular communication function off, the fact that it has been determined is stored in, for example, the storage device 9. On the other hand, if there is no undetermined hybrid smart meter 5, the candidate selection unit 22 ends the operation of prerequisite operation 0 in FIG. 7.

[0059] When the candidate selection unit 22 completes the prerequisite operation 0, the process proceeds to operation 1. Operation 1 will be described with reference to Fig. 8. As shown in Fig. 8, the steps in operation 1 are steps S11 to S15.

[0060] In Operation 1, the candidate selection unit 22 proceeds to step S11 when starting Operation 1. In step S11, the candidate selection unit 22 selects an undetermined hybrid smart meter 5 from the selection preparation list 0. When the candidate selection unit 22 selects an undetermined hybrid smart meter 5 in Operation 1, the process proceeds to step S12.

[0061] In step S12, the candidate selection unit 22 determines whether the error rate of the selected undetermined hybrid smart meter 5 is equal to or greater than a threshold. Here, the error rate is, for example, a packet error rate or the number of channel access errors. If the error rate is not equal to or greater than the threshold, the process returns to step S11. Here, when the process returns to step S11, for the hybrid smart meter 5 whose error rate was determined not to be equal to or greater than the threshold in step S12, the fact that the hybrid smart meter 5 has been determined is stored, for example, in the storage device 9. On the other hand, if the error rate of the selected undetermined hybrid smart meter 5 is equal to or greater than the threshold, the process proceeds to step S13.

[0062] In step S13, the candidate selection unit 22 determines whether the data transfer volume of the selected undetermined hybrid smart meter 5 is equal to or greater than the threshold. If the data transfer volume of the selected undetermined hybrid smart meter 5 is not equal to or greater than the threshold, the process returns to step S11. Here, when the process returns to step S11, for the hybrid smart meter 5 determined in step S13 that the data transfer volume is not equal to or greater than the threshold, the fact that the determination has been made is stored, for example, in the storage device 9. On the other hand, if the data transfer volume of the selected undetermined hybrid smart meter 5 is equal to or greater than the threshold, the process proceeds to step S14.

[0063] In step S14, the candidate selection unit 22 registers the hybrid smart meter 5 selected in step S11, whose error rate is equal to or greater than the threshold and whose data transfer amount is equal to or greater than the threshold, in the selection list 1. After the hybrid smart meter 5 is registered in the selection list 1, the process proceeds to step S15.

[0064] In step S15, the candidate selection unit 22 determines whether or not there is an undetermined hybrid smart meter 5 in the selection preparation list 0. If there is an undetermined hybrid smart meter 5, the process returns to step S11. Here, when the process returns to step S11, for the hybrid smart meter 5 determined in step S12 to have an error rate equal to or greater than the threshold and the data transfer amount equal to or greater than the threshold in step S13, the fact that it has been determined is stored in, for example, the storage device 9. On the other hand, if there is no undetermined hybrid smart meter 5, the candidate selection unit 22 ends operation 1 and proceeds to operation 2.

[0065] Operation 2 will be described with reference to Fig. 9. As shown in Fig. 9, the steps in Operation 2 are steps S21 to S24.

[0066] In Operation 2, the candidate selection unit 22 proceeds to step S21 when it starts Operation 2. In step S21, the candidate selection unit 22 selects an undetermined hybrid smart meter 5 from the selection list 1. When the candidate selection unit 22 selects an undetermined hybrid smart meter 5 in Operation 2, the process proceeds to step S22.

[0067] In step S22, the candidate selection unit 22 determines whether there is another hybrid smart meter 5 registered in the selection list 1 as a subordinate terminal of the selected undetermined hybrid smart meter 5. If there is another hybrid smart meter 5 registered in the selection list 1 as a subordinate terminal of the selected undetermined hybrid smart meter 5, the process returns to step S21. Here, when the process returns to step S21, for the hybrid smart meter 5 determined in step S22 to have another hybrid smart meter 5 registered in the selection list 1 as a subordinate terminal, the fact that the determination has been made is stored in, for example, the storage device 9. On the other hand, if there is no other hybrid smart meter 5 registered in the selection list 1 as a subordinate terminal of the selected undetermined hybrid smart meter 5, the process proceeds to step S23.

[0068] In step S23, the candidate selection unit 22 selects a hybrid smart meter 5 from selection list 1 and registers it in selection list 2 for which it has determined in step S22 that there are no other hybrid smart meters 5 registered in selection list 1 as subordinate terminals. In other words, the hybrid smart meter 5 on the downstream side of selection list 1 is registered in selection list 2. Once registered, the process proceeds to step S24.

[0069] In step S23, the candidate selection unit 22 determines whether there is an undetermined hybrid smart meter 5 in the selection list 1. If there is an undetermined hybrid smart meter 5, the process returns to step S21. Here, when the process returns to step S21, for the hybrid smart meter 5 for which it was determined in step S22 that there is no subordinate terminal, the fact that the determination has been made is stored, for example, in the storage device 9. On the other hand, if there is no undetermined hybrid smart meter 5, the candidate selection unit 22 ends operation 2 and proceeds to operation 3.

[0070] Operation 3 will be described with reference to Fig. 10. As shown in Fig. 10, the steps in Operation 3 are steps S31 to S35.

[0071] In Operation 3, the candidate selection unit 22 proceeds to step S31 when starting Operation 3. In step S31, the candidate selection unit 22 selects an undetermined hybrid smart meter 5 from the selection list 2. When the candidate selection unit 22 selects an undetermined hybrid smart meter 5 in Operation 3, the process proceeds to step S32.

[0072] In step S32, the candidate selection unit 22 determines whether the selected undetermined hybrid smart meter 5 corresponds to a hybrid smart meter 5 that was used as a node constituting the information transmission path of another hybrid smart meter 5 or a multi-hop smart meter 7 until the time when the determination in step S32 was made. If the selected undetermined hybrid smart meter 5 does not correspond to a hybrid smart meter 5 that was used as an information transmission path until the time when the determination was made, the process proceeds to step S33. On the other hand, if the selected undetermined hybrid smart meter 5 corresponds to a hybrid smart meter 5 that was used as an information transmission path until the time when the determination was made, the process proceeds to step S34.

[0073] In step S33, the candidate selection unit 22 compares the number of hops of the selected undetermined hybrid smart meter 5 with the number of hops of other smart meters that had been used as information transmission paths up until the time of determination, and determines which has a larger number of hops. The number of hops is a number indicating how many hybrid smart meters 5 or multi-hop smart meters 7 are passed through when transmitting information from a certain hybrid smart meter 5 to an accommodation node via multi-hop communication. The other smart meters referred to here are, for example, hybrid smart meters 5 that had been used to transmit information to the same accommodation node as the selected undetermined hybrid smart meter 5 up until the time of determination.

[0074] If the number of hops of the selected undetermined hybrid smart meter 5 is greater than the number of hops of other smart meters that had been used as information transmission paths up until the time of determination, the process proceeds to step S34. On the other hand, if the number of hops of the selected undetermined hybrid smart meter 5 is less than the number of hops of other smart meters that had been used as information transmission paths up until the time of determination, the process returns to step S31. Here, when the process returns to step S31, the hybrid smart meter 5 whose hop count was determined in step S33 is stored, for example, in the storage device 9, as having been determined.

[0075] In step S34, the candidate selection unit 22 registers the selected undetermined hybrid smart meter 5 in the selection list 3. After registration, the process proceeds to step S35.

[0076] In step S35, the candidate selection unit 22 determines whether there is an undetermined hybrid smart meter 5 in the selection list 2. If there is an undetermined hybrid smart meter 5, the process returns to step S31. Here, when the process returns to step S31, for a hybrid smart meter 5 that corresponds to the hybrid smart meter 5 that was used as an information transmission path until the determination was made in step S32, or that has been determined to have a larger number of hops than when it was used as an information transmission path until the determination was made in step S33, the fact that it has been determined is stored, for example, in the storage device 9. On the other hand, if there is no undetermined hybrid smart meter 5, the candidate selection unit 22 ends operation 3 and proceeds to operation 4.

[0077] Operation 4 will be described with reference to Fig. 11. As shown in Fig. 11, the steps in Operation 4 are steps S41 to S46.

[0078] In Operation 4, the candidate selection unit 22 proceeds to step S41 when starting Operation 4. In step S41, the candidate selection unit 22 selects an undetermined hybrid smart meter 5 from the selection list 3. When the determination in Operation 4 selects an undetermined hybrid smart meter 5, the process proceeds to step S42.

[0079] In step S42, the candidate selection unit 22 determines whether the number of subordinate terminals of the selected undetermined hybrid smart meter 5 is equal to or greater than a threshold. If the number of subordinate terminals is equal to or greater than the threshold, the process proceeds to step S43. If the number of subordinate terminals is equal to or less than the threshold, the process returns to step S41. Here, when the process returns to step S41, the fact that the determined hybrid smart meter 5 has been determined is stored in, for example, a storage device.

[0080] In step S43, the candidate selection unit 22 registers the hybrid smart meters 5 whose number of subordinate terminals is equal to or greater than the threshold in the selection list 4. As a result, hybrid smart meters 5 whose number of subordinate terminals is equal to or greater than the threshold, that is, whose amount of information to be transmitted is equal to or greater than the threshold, are registered in the selection list 4. After registration, the process proceeds to step S44.

[0081] In step S44, the candidate selection unit 22 selects one undetermined hybrid smart meter 5 from the selection list 4. After the selection, the process proceeds to step S45.

[0082] In step S45, the control signal transmitter 24 transmits a control signal to turn on the cellular communication function of the selected one undetermined hybrid smart meter 5. After transmitting the control signal, the process proceeds to step S46.

[0083] In step S46, the determination unit 23 determines whether the RSRP received from one hybrid smart meter 5 with the cellular communication function turned on is equal to or less than a threshold. If the RSRP is equal to or less than the threshold, the process proceeds to step S47. If the RSRP is equal to or greater than the threshold, the process proceeds to step S48.

[0084] In step S47, the control signal transmitter 24 transmits a control signal to turn off the cellular communication function of the selected undetermined hybrid smart meter 5. After transmitting the control signal, the process proceeds to step S48.

[0085] In step S48, the candidate selection unit 22 determines whether there is an undetermined hybrid smart meter 5 in the selection list 4. If there is an undetermined hybrid smart meter 5 in the selection list 4, the process returns to step S44. Here, when the process returns to step S44, the fact that the determined hybrid smart meter 5 has been determined is stored in, for example, the storage device 9. If there is no undetermined hybrid smart meter 5 in the selection list 4, operation 4 ends.

[0086] In steps S44 to S48, the candidate selection unit 22 performs operations for each hybrid smart meter 5, but it may also be possible to send a control signal to turn on the cellular communication function for all hybrid smart meters 5 registered in the selection list 4 at the same time, and to send a control signal to turn off the cellular communication function for all hybrid smart meters 5 whose RSRP is below the threshold value at the same time.

[0087] Next, the operation performed by the redundancy determination unit 54 of the hybrid smart meter 5 will be described. The redundancy determination unit 54 executes its operation after Operation 4 of the network management device 2 ends, and before the network management device 2 starts the next prerequisite operation 0. It is assumed that the operation of the redundancy determination unit 54 is executed so as to end before the next prerequisite operation 0 of the network management device 2 starts. FIG. 12 is a flowchart showing the determination operation performed by the redundancy determination unit 54 to determine whether to make the transmission path to the parent node redundant. Upon acquiring communication information of other smart meters from the multi-hop communication management unit 53 or the cellular communication management unit 58, the redundancy determination unit 54 starts the determination operation to determine whether to make the transmission path to the parent node redundant. In step SS1, the redundancy determination unit 54 uses the acquired information to determine whether the number of local repairs of the parent node is equal to or greater than a threshold. Here, the number of local repairs of the parent node refers to the number of child nodes, i.e., hybrid smart meters 5 or multi-hop smart meters 7, whose information is stored by the parent node. It is noted that a child node refers to a node that directly transmits information to the parent node. If the number of local repairs of the parent node is equal to or greater than the threshold in step SS1, the process proceeds to step SS2. If the number of local repairs of the parent node is not equal to or greater than the threshold in step SS1, the process proceeds to step SS4.

[0088] In step SS2, the redundancy determination unit 54 determines whether the number of accommodated nodes is equal to or less than a threshold. If the number of accommodated nodes is equal to or greater than the threshold in step SS2, the process proceeds to step SS3. If the number of accommodated nodes is not equal to or greater than the threshold in step SS2, the process proceeds to step SS4.

[0089] In step SS3, the redundancy determination unit 54 determines whether to make the transmission path to the parent node redundant. If the redundancy determination unit 54 determines that the transmission path to the parent node should be made redundant, the process proceeds to step SS5.

[0090] In step SS4, the redundancy determination unit 54 determines not to make the transmission path to the parent node redundant. If the redundancy determination unit 54 determines not to make the transmission path to the parent node redundant, the process proceeds to step SS5.

[0091] In step SS5, the redundancy determination unit 54 transmits the determination result, indicating whether or not to make the transmission path to the parent node redundant, to the redundant route control unit 55. When the redundancy determination unit 54 transmits the determination result to the redundant route control unit 55, the flow ends.

[0092] 13 is a flowchart showing the determination operation performed by the redundancy determination unit 54 to determine whether or not to make the transmission path to the destination node redundant. When the redundancy determination unit 54 acquires communication information of other smart meters from the multi-hop communication management unit 53 or the cellular communication management unit 58, the redundancy determination unit 54 starts the determination operation to determine whether or not to make the transmission path to the destination node redundant. In step SS6, the redundancy determination unit 54 uses the acquired information to determine whether or not the number of channel access errors of the destination node is equal to or greater than a threshold. If the number of channel access errors of the destination node is equal to or greater than the threshold in step SS6, the process proceeds to step SS7. If the number of channel access errors of the destination node is not equal to or greater than the threshold in step SS6, the process proceeds to step SS9.

[0093] In step SS7, the redundancy determination unit 54 determines whether the number of accommodated nodes is equal to or less than a threshold. If the number of accommodated nodes is equal to or less than the threshold in step SS7, the process proceeds to step SS8. If the number of accommodated nodes is not equal to or less than the threshold in step SS7, the process proceeds to step SS9.

[0094] In step SS8, the redundancy determination unit 54 determines whether to make the transmission path to the destination node redundant. If the redundancy determination unit 54 determines that the transmission path to the destination node is to be made redundant, the process proceeds to step SS10.

[0095] In step SS9, the redundancy determination unit 54 determines not to make the transmission path to the destination node redundant. If the redundancy determination unit 54 determines not to make the transmission path to the destination node redundant, the process proceeds to step SS10.

[0096] In step SS10, the redundancy determination unit 54 transmits the determination result, which indicates whether or not to make the transmission path to the destination node redundant, to the redundant route control unit 55. When the redundancy determination unit 54 transmits the determination result to the redundant route control unit 55, the flow ends.

[0097] Although the example has been described in which the operation of the redundancy determination unit 54 is completed before the next prerequisite operation 0 of the network management device 2 starts, the prerequisite operations 0 and operations 1 to 4 of the network management device 2 and the operation of the redundancy determination unit 54 may be executed independently in terms of time. In other words, the operation of the redundancy determination unit 54 may be executed at any timing.

[0098] Furthermore, although the case where the network management device 2 constructs the network has been described, the accommodation node may construct the network of the smart meters under its control. Specifically, for example, the information acquisition unit 21, the candidate selection unit 22, the determination unit 23, and the control signal transmission unit 24 are not limited to being provided in the network management device 2, but similar configurations may be provided in each accommodation node, and these may construct the network of the smart meters under its control instead of the network management device 2. In this case, the network management device 2 collectively collects the information collected by each accommodation node. Even in this case, the network management device 2 can hold all information related to the network configuration, just as in the case where the network management device 2 constructs the network.

[0099] The smart meter communication system 1 of the first embodiment includes a candidate selection unit 22 that selects a candidate hybrid smart meter 5 for which cellular communication is to be turned on, using the topology information and communication information acquired by the information acquisition unit 21, and a control signal transmission unit 24 that transmits a control signal for turning on the cellular communication function to the selected candidate hybrid smart meter 5. Therefore, the smart meter communication system 1 selects a candidate hybrid smart meter 5 for which cellular communication is to be turned on, using topology information that indicates the communication connection relationship and communication information that is information that indicates the communication quality corresponding to the topology information, and transmits a control signal for turning on the cellular communication function of the selected candidate hybrid smart meter 5. In other words, since a transmission path for transmitting information is secured before transmitting information, there is no need to switch communication, and highly reliable communication can be achieved.

[0100] Variation 1. Variation 1 describes a method in which the network management device 2 uses carrier information to build a more stable communication network than in embodiment 1. Figure 14 is a flowchart showing operation 5, which is an additional operation performed in addition to operation 4, which is performed in the same way as in embodiment 1, among the operations performed by the network management device 2 according to variation 1 to build a network. Variation 1 differs from embodiment 1 only in that selection list 5 is created using carrier information in addition to selection list 4, and therefore a description of the configuration of the network management device 2 according to variation 1 and similar operations will be omitted.

[0101] In step S51, the candidate selection unit 22 selects an undetermined hybrid smart meter 5 from the selection list 3. Once the candidate selection unit 22 has made a selection, the process proceeds to step S52.

[0102] In step S52, the candidate selection unit 22 checks the carrier information for each of the accommodation node of the undetermined hybrid smart meter 5 selected from the selection list 3 and the terminals subordinate to the accommodation node, and extracts a carrier that is not used by the accommodation node and is used by the terminals subordinate to the accommodation node. For example, if there are three mobile phone carriers, A, B, and C, and the accommodation node has a contract with A and the terminals subordinate to the accommodation node have a contract with B or C, the candidate selection unit 22 extracts B or C, which is the carrier of the terminals subordinate to the accommodation node.

[0103] Next, in step S53, the candidate selection unit 22 registers the hybrid smart meter 5 that uses the extracted carrier among the subordinate terminals of the accommodation node as a secondary accommodation node in the selection list 5. Here, the secondary accommodation node is a candidate node that can become a new accommodation node in place of the current accommodation node. Once the candidate selection unit 22 has registered the secondary accommodation node in the selection list 5, the process proceeds to step S54.

[0104] In step S54, if there is an undetermined hybrid smart meter 5 in the selection list 3, the process returns to step S51. Here, when the process returns to step S51, the fact that the hybrid smart meter 5 selected in step S51 has been determined is stored, for example, in the storage device 9. In step S54, if there is no undetermined hybrid smart meter 5 in the selection list 3, the operation ends.

[0105] In the first modification, for example, when information indicating that a communication failure has occurred in the cellular communication managed by company A is transmitted to the network management device 2, the network management device 2 changes the destination of the information transmitted by each smart meter to multiple secondary accommodation nodes registered in selection list 5 based on the received information and the carrier information of the secondary accommodation nodes, and transmits information about the changed destination to each smart meter. Specifically, when the candidate selection unit 22 receives information indicating that a communication failure has occurred in the cellular communication, it can change the destination of the information transmitted by each smart meter to multiple secondary accommodation nodes by performing the same operation as step S44 and subsequent steps in operation 4 shown in Fig. 11 using selection list 5 instead of selection list 4.

[0106] In this way, by creating a selection list 5 in addition to selection list 4 by also using carrier information to register the secondary destination node in selection list 5, for example, in the event of a communication failure in the cellular communication of a mobile carrier A, it is possible to construct a network using a secondary destination node that uses the cellular communication of another mobile carrier, B or C, excluding A.

[0107] 1 Smart meter communication system, 2 Network management device, 3 Data collection device, 4 Cellular base station, 5 Hybrid smart meter, 6 Cellular smart meter, 7 Multi-hop smart meter, 8 Arithmetic unit, 9 Storage device, 10 Input device, 11 Auxiliary storage device, 12 Output device, 13 Signal line, 21 Information acquisition unit, 22 Candidate selection unit, 23 Determination unit, 24 Control signal transmission unit, 51 Metering unit, 52 Multi-hop communication unit, 53 Multi-hop communication management unit, 54 Redundancy determination unit, 55 Redundant route control unit, 56 Multi-hop route management unit, 57 Cellular communication unit, 58 Cellular communication management unit, 59 Cellular route management unit, 61 Metering unit, 67 Cellular communication unit, 68 Cellular communication management unit, 69 Cellular route management unit, 71 Metering unit, 72 Multi-hop communication unit, 73 Multi-hop communication management unit, 64 Redundancy determination unit, 65 Redundant Route Control Unit, 66 Multi-hop Route Management Unit

Claims

1. A smart meter communication system comprising: a plurality of hybrid smart meters each having two types of communication functions, a cellular communication function and a multi-hop communication function, and each capable of switching the cellular communication function on and off; an information acquisition unit that acquires information indicating the communication connection relationship between the plurality of smart meters including the hybrid smart meters, the information being topology information that changes when the cellular communication function of one or more of the hybrid smart meters is turned on and off, and communication information that indicates the communication quality between the plurality of smart meters, the communication information changing in accordance with changes in the topology information; a candidate selection unit that uses the acquired communication information and topology information to select a candidate hybrid smart meter for which the cellular communication function will be turned on; and a control signal transmission unit that transmits a control signal to turn on the cellular communication function of the hybrid smart meter selected by the candidate selection unit.

2. The smart meter communication system according to claim 1, wherein the candidate selection unit selects the hybrid smart meter whose communication quality of multi-hop communication is lower than a predetermined standard as the candidate for turning on the cellular communication function.

3. The smart meter communication system of claim 1, further comprising: an information acquisition unit that, when the cellular communication function of the hybrid smart meter selected by the candidate selection unit is turned on, acquires the signal strength in cellular communication using the cellular communication function from the hybrid smart meter that has the cellular communication function turned on; and a judgment unit that, when the signal strength in the cellular communication is below a threshold, determines to turn off the cellular communication function, and, when the signal strength in the cellular communication is above a threshold, determines to keep the cellular communication function turned on. 4.) The smart meter communication system of claim 2, further comprising a redundancy determination unit that determines to implement redundancy by providing two or more transmission paths when transmitting information using the multi-hop communication function if the communication quality of the hybrid smart meter that was not selected as a candidate for turning on the cellular communication function is below a predetermined standard.

5. A network management device comprising: an information acquisition unit that acquires information indicating the communication connection relationship between multiple smart meters, including one or more hybrid smart meters that have two types of communication functions, a cellular communication function and a multi-hop communication function, and that can switch the cellular communication function on and off, the information being topology information that changes when the cellular communication function of one or more of the hybrid smart meters is turned on and off, and communication information that indicates the communication quality between the multiple smart meters, the communication information changing as the topology information changes; a candidate selection unit that uses the acquired communication information and topology information to select a candidate hybrid smart meter for which the cellular communication function will be turned on; and a control signal transmission unit that transmits a control signal to turn on the cellular communication function of the selected candidate hybrid smart meter.

6. The network management device according to claim 5, wherein the candidate selection unit selects the hybrid smart meter whose communication quality of multi-hop communication is lower than a predetermined standard as the candidate for turning on the cellular communication function.

7. A smart meter communication program that causes a computer to execute the following steps: an information acquisition step that acquires information indicating the communication connection relationship between multiple smart meters, including multiple hybrid smart meters that have two types of communication functions, cellular communication function and multi-hop communication function, and that can switch the cellular communication function on and off, and that acquires topology information that changes when the cellular communication function of one or more of the hybrid smart meters is turned on and off, and communication information that indicates the communication quality between the multiple smart meters, and that changes as the topology information changes; a candidate selection step that uses the acquired communication information and topology information to select a candidate hybrid smart meter that will turn on the cellular communication function; and a control signal transmission step that transmits a control signal that turns on the cellular communication function of the selected candidate hybrid smart meter.

8. A redundancy program that causes a hybrid smart meter having two types of communication functions, a cellular communication function and a multi-hop communication function, to execute a redundancy determination step that uses communication information indicating the communication quality between multiple smart meters, including multiple hybrid smart meters that can switch the cellular communication function on and off, to determine that redundancy should be implemented to use two or more transmission paths when transmitting information using the multi-hop communication function if the communication quality of the hybrid smart meter not selected as a candidate for turning on the cellular communication function is below a predetermined standard, and a multi-hop communication management step that transmits information using the multi-hop communication function.

9. A smart meter communication method comprising: an information acquisition step of acquiring information indicating the communication connection relationship between multiple smart meters, including multiple hybrid smart meters having two types of communication functions, namely a cellular communication function and a multi-hop communication function, and capable of switching the cellular communication function on and off, the information being topology information that changes when the cellular communication function of one or more of the hybrid smart meters is turned on and off, and communication information that indicates the communication quality between the multiple smart meters, the communication information changing as the topology information changes; a candidate selection step of selecting a candidate hybrid smart meter for which the cellular communication function will be turned on using the communication information and topology information acquired in the information acquisition step; and a control signal transmission step of transmitting a control signal to turn on the cellular communication function of the candidate hybrid smart meter selected in the candidate selection step.

10. A redundancy method comprising: a redundancy determination step for determining, using communication information indicating the communication quality between multiple smart meters, including multiple hybrid smart meters having two types of communication functions, namely a cellular communication function and a multi-hop communication function, and capable of switching the cellular communication function on and off, to implement redundancy by increasing the number of transmission paths to two or more when transmitting information using the multi-hop communication function if the communication quality of the hybrid smart meters not selected as candidates for turning on the cellular communication function is below a predetermined standard; and a multi-hop communication management step for transmitting information using the multi-hop communication function.

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