Wireless communication device, wireless communication method, and computer program

Abstract

To suppress deterioration in communication quality and reduce the cost required for network construction and operation.SOLUTION: When a smart meter 10 starts up, the smart meter starts up a second communication unit 18 that performs wireless multi-hop communication and causes it to search for a master device of multi-hop communication as a slave device of a multi-hop wireless communication network. When the master device is detected, the smart meter operates itself as a slave device of the multi-hop wireless communication network. When the master device is not detected, the smart meter starts up a first communication unit 17 that performs cellular wireless communication and connects to a cellular base station 20, and operates its own device as the master device of the multi-hop wireless communication network.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a wireless communication device, a wireless communication method, and a computer program. [Background technology]

[0002] Conventional smart meter networks have two wireless methods: a multi-hop method and a cellular method that uses the mobile phone network provided by a telecommunications carrier.

[0003] The multi-hop method is a system in which a wireless node using a 920 MHz band specified low-power radio installed in each smart meter searches for nearby nodes, autonomously builds a network, and collects data using a bucket brigade system. This eliminates the need for communication running costs and is suitable for areas with high residential density. On the other hand, the portable method is a system in which a module that can connect to a mobile phone network is installed in the smart meter, and each smart meter connects to a communication carrier's base station to collect data, making it suitable for suburban and mountainous areas. In relation to the portable method, Patent Document 1 describes a technology that captures the location relationship and situation and connects a wireless terminal to the appropriate wireless terminal housing device without pre-registering the location information of the wireless terminal housing device. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-131190 Summary of the Invention [Problem to be solved by the invention]

[0005] However, because the mobile system uses the mobile phone network, there are challenges in deploying it in residential areas in terms of communication costs. Conventional technology uses two wireless systems, the multi-hop system and the mobile system, in combination. In this case, it is necessary to investigate the radio wave conditions at the installation location in advance and then install a smart meter with the appropriate communication system, which poses the challenge of requiring a huge amount of investigation.

[0006] Smart meters have an operational period of about 10 years after installation, and if environmental changes during that time make it impossible to communicate using the method selected at the time of installation, the smart meter must be replaced. For example, with the portable method, dead zones can occur in the shadows of buildings, so if dead zones occur due to the construction of a new building, it will be necessary to add base stations in appropriate locations as a countermeasure.

[0007] The present invention has been made in consideration of the above points, and aims to provide a wireless communication device, a wireless communication method, and a computer program that can suppress degradation of communication quality and reduce the costs required for building and operating a network compared to conventional methods. [Means for solving the problem]

[0008] In order to solve the above problem, according to one aspect of the present invention, there is provided a wireless communication device comprising: a first communication unit that performs cellular wireless communication; a second communication unit that performs wireless multi-hop communication; a search unit that searches for nearby wireless base stations using the first communication unit; and a communication control unit that controls connection with a destination device, wherein the communication control unit activates the second communication unit at startup and causes the search unit to search for a master device of the multi-hop wireless communication network as a slave device of the multi-hop wireless communication network, and if the master device is detected, causes the device to operate as a slave device of the multi-hop wireless communication network, and if the master device is not detected, causes the first communication unit to connect to a cellular base station and cause the device to operate as a master device of the multi-hop wireless communication network.

[0009] When communication with a master device of the multi-hop wireless communication network becomes impossible, the communication control unit may cause the searching unit to search for another master device of the multi-hop wireless communication network.

[0010] If the search unit does not detect a parent device as a result of its search, the communication control unit may activate the first communication unit to connect to a cellular base station and operate the device as a parent device of the multi-hop wireless communication network.

[0011] When communication with the base station becomes impossible, the communication control unit may restart the device itself after notifying a restart instruction from the second communication unit to the device of the multihop wireless communication network. In this case, the communication control unit may attempt to operate the device as a master device of the multihop wireless communication network after restarting the device itself, and if the device fails to operate as a master device for a predetermined period of time or a predetermined number of times, cause the search unit to search for a master device of the multihop wireless communication network as the device of the multihop wireless communication network. In this case, the communication control unit may set a predetermined flag before restarting the device itself, and if the flag is set after restarting the device itself, cause the search unit to search for a master device of the multihop wireless communication network as the device of the multihop wireless communication network without attempting to operate the device as a master device of the multihop wireless communication network.

[0012] The communication control unit may cause the search unit to search, at a predetermined interval, whether or not there is a device that has newly joined the multi-hop wireless communication network.

[0013] If the search unit finds a device that has newly joined the multi-hop wireless communication network as a result of its search, the communication control unit may determine whether to change the connection destination of the multi-hop communication to the newly joined device.

[0014] The device may further include a metering unit that measures data relating to the amount of power used at the location where the device is installed.

[0015] In order to solve the above problem, according to another aspect of the present invention, a wireless communication method is provided in which a processor, upon startup, activates a second communication unit that performs wireless multi-hop communication, and searches for a parent device of the multi-hop wireless communication network as a child device of the multi-hop wireless communication network, and if a parent device is detected, causes the device to operate as a child device of the multi-hop wireless communication network, and if a parent device is not detected, activates a first communication unit that performs cellular wireless communication, connects to a cellular base station, and causes the device to operate as a parent device of the multi-hop wireless communication network.

[0016] In order to solve the above problem, according to another aspect of the present invention, a computer program is provided which causes a computer to execute processing such that, upon startup, a second communication unit that performs wireless multi-hop communication is started, and the second communication unit searches for a master unit of the multi-hop wireless communication network as a slave unit of the multi-hop wireless communication network; if a master unit is detected, the computer operates as a slave unit of the multi-hop wireless communication network; and if a master unit is not detected, the computer operates as a master unit of the multi-hop wireless communication network by starting a first communication unit that performs cellular wireless communication, connecting to a cellular base station, and operating the computer as a master unit of the multi-hop wireless communication network. [Effects of the Invention]

[0017] According to the present invention, it is possible to provide a wireless communication device, a wireless communication method, and a computer program that can suppress degradation of communication quality and reduce the costs required for building and operating a network compared to conventional methods. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a diagram showing a schematic configuration of a communication system including a smart meter according to an embodiment. [Figure 2] FIG. 2 is a block diagram showing the hardware configuration of a smart meter. [Figure 3] FIG. 2 is a block diagram showing an example of a functional configuration of a smart meter. [Figure 4]FIG. 2 is a sequence diagram showing the flow of a network construction process of each device in the communication system. [Figure 5] FIG. 2 is a sequence diagram showing the flow of a network construction process of each device in the communication system. [Figure 6] FIG. 1 is a diagram showing a state in which a multi-hop wireless communication network is constructed. [Figure 7] FIG. 1 is a diagram showing a state in which a multi-hop wireless communication network is constructed. [Figure 8] FIG. 1 is a diagram showing a state in which a multi-hop wireless communication network is constructed. [Figure 9] FIG. 2 is a sequence diagram showing the flow of a network construction process of each device in the communication system. [Figure 10] FIG. 1 is a diagram showing a state in which a multi-hop wireless communication network is constructed. DETAILED DESCRIPTION OF THE INVENTION

[0019] An example of an embodiment of the present invention will be described below with reference to the drawings. The same reference numerals are used throughout the drawings to designate identical or equivalent components and parts. The dimensional proportions of the drawings are exaggerated for illustrative purposes and may differ from the actual proportions.

[0020] FIG. 1 is a diagram showing a schematic configuration of a communication system including a smart meter according to this embodiment.

[0021] The communication system according to this embodiment includes smart meters 10A to 10E, which are examples of wireless communication devices of the present invention, a cellular communication base station 20, and a server 30. The base station 20 and the server 30 are connected via a WAN (Wide Area Network) line 40 of a mobile phone service provider.

[0022] The smart meters 10A to 10E are devices installed in homes, businesses, etc., and measure the amount of electricity used in the homes, businesses, etc. The smart meters 10A to 10E each include a metering unit 110A to 110E that measures the amount of electricity used. The smart meters 10A to 10E are configured to perform cellular wireless communication using first communication units 17A to 17E, and wireless multi-hop communication using radio waves in a predetermined frequency band (for example, the 920 MHz band) using second communication units 18A to 18E, respectively. The first communication units 17A to 17E are connected to the base station 20 via a mobile phone line. When multi-hop communication is performed, no mobile phone line usage fees are incurred.

[0023] 1, due to the reach of radio waves in the 920 MHz band, smart meters 10B, 10D, and 10E are located in positions where they can be connected to the second communication unit 18A of smart meter 10A, but smart meter 10C is located in a position where it cannot be connected to the second communication unit 18A of smart meter 10A. In this case, smart meter 10C can be connected to the second communication unit 18A of smart meter 10A via the second communication unit 18B of smart meter 10A of smart meter 10B by multi-hop communication.

[0024] When activated, the smart meters 10A to 10E according to this embodiment start up as slave devices (routers) of a multi-hop wireless communication network and search for a master device (coordinator) of the multi-hop wireless communication network in the vicinity. If a master device of the multi-hop wireless communication network exists, the smart meters 10A to 10E continue to operate as slave devices and form a multi-hop wireless communication network with the master device. On the other hand, if a master device of the multi-hop wireless communication network does not exist, the smart meters 10A to 10E communicate with the base station 20 and operate as a master device of the multi-hop wireless communication network.

[0025] In this way, by determining whether a master device of the multi-hop wireless communication network exists at the time of startup, the smart meters 10A to 10E can determine whether to operate as a master device or a slave device of the multi-hop wireless communication network depending on the surrounding environment. As a result, the smart meters 10A to 10E can suppress degradation of communication quality and reduce the costs required for building and operating the network.

[0026] The server 30 aggregates the power measurement data measured by the smart meters 10A to 10E. The server 30 includes a HES (Head End System). The HES terminates communication with the smart meters 10A to 10E via a WAN line 40 of a mobile phone service provider.

[0027] In the following description, the smart meters 10A to 10E will be simply referred to as the smart meter 10 when there is no need to distinguish between them.

[0028] FIG. 2 is a block diagram showing the hardware configuration of the smart meter 10. As shown in FIG.

[0029] 2, the smart meter 10 includes a CPU (Central Processing Unit) 11, a ROM (Read Only Memory) 12, a RAM (Random Access Memory) 13, a storage 14, an input unit 15, a display unit 16, a first communication unit 17, and a second communication unit 18. Each component is connected to each other via a bus 19 so as to be able to communicate with each other.

[0030] CPU 11 is a central processing unit that executes various programs and controls each component. That is, CPU 11 reads programs from ROM 12 or storage 14 and executes the programs using RAM 13 as a work area. CPU 11 controls the above components and performs various arithmetic processing in accordance with the programs recorded in ROM 12 or storage 14. In this embodiment, ROM 12 or storage 14 stores computer programs related to the operation of the communication system.

[0031] The ROM 12 stores various programs and various data. The RAM 13 temporarily stores programs or data as a working area. The storage 14 is configured with a storage device such as an HDD (Hard Disk Drive), SSD (Solid State Drive), or flash memory, and stores various programs including the operating system and various data.

[0032] The input unit 15 is used to input various types of information to the smart meter 10 .

[0033] The display unit 16 is, for example, a liquid crystal display, and displays various information. The display unit 16 may also function as the input unit 15 by adopting a touch panel system.

[0034] The first communication unit 17 is an interface for communicating with the base station 20, and uses cellular communication standards such as 3G, 4G, and 5G.

[0035] The second communication unit 18 is an interface for communicating with other smart meters 10 using radio waves in a predetermined frequency band, and in this embodiment, a multi-hop communication standard using radio waves in the 920 MHz band is used.

[0036] When executing the above computer programs, the smart meter 10 uses the above hardware resources to realize various functions. The functional configuration realized by the smart meter 10 will be described.

[0037] FIG. 3 is a block diagram showing an example of the functional configuration of the smart meter 10. As shown in FIG.

[0038] 3, the smart meter 10 has, as functional components, a metering unit 110, a searching unit 120, and a communication control unit 130. Each functional component is realized by the CPU 11 reading and executing a computer program stored in the ROM 12 or the storage 14.

[0039] The metering unit 110 measures data related to the amount of electricity used at the location where the smart meter 10 is installed. Information on the data related to the amount of electricity measured by the metering unit 110 is periodically transmitted as metering data to the server 30 via a mobile phone line from the smart meter 10 that has become the master device of the constructed multi-hop wireless communication network. The metering data may include the meter value, meter information, and the time of measurement.

[0040] The search unit 120 searches for the smart meter 10 that is the master of the multi-hop wireless communication network under the control of the communication control unit 130.

[0041] The communication control unit 130 controls communication between the smart meter 10 and other smart meters 10 or the base station 20. In detail, the communication control unit 130 activates the second communication unit 18 at startup and causes the searching unit 120 to search for a master unit of the multi-hop wireless communication network as a slave unit of the multi-hop wireless communication network. If the searching unit 120 detects a smart meter 10 that is a master unit, the communication control unit 130 causes the smart meter 10 to operate as a slave unit of the multi-hop wireless communication network. On the other hand, if the searching unit 120 does not detect a smart meter 10 that is a master unit, the communication control unit 130 activates the first communication unit 17 to connect to the base station 20 and causes the smart meter 10 to operate as a master unit of the multi-hop wireless communication network.

[0042] When communication with the smart meter 10 that is the master device of the established multi-hop wireless communication network becomes impossible, the communication control unit 130 causes the searching unit 120 to search for another smart meter 10 that is the master device of the multi-hop communication. Then, when the search unit 120 does not detect another smart meter 10 that is the master device as a result of the search, the communication control unit 130 activates the first communication unit 17 to connect to the base station 20 and causes the smart meter 10 to operate as the master device of the multi-hop wireless communication network.

[0043] Furthermore, when the communication control unit 130 is operating as a master device and communication with the base station 20 becomes impossible, the communication control unit 130 notifies a restart instruction to the smart meter 10 that is a slave device of the multi-hop wireless communication network from the second communication unit 18. Then, after notifying the smart meter 10 that is a slave device of the restart instruction, the communication control unit 130 restarts the smart meter 10. After the restart, the communication control unit 130 starts up the second communication unit 18 and causes the searching unit 120 to search for the smart meter 10 that is a master device of the multi-hop wireless communication network as a slave device of the multi-hop wireless communication network.

[0044] With this configuration, the smart meter 10 can determine whether to operate as a master or slave in a multi-hop wireless communication network depending on the surrounding environment. As a result, the smart meter 10 can suppress degradation of communication quality and reduce the costs required for building and operating the network.

[0045] Next, the operation of each device in the communication system will be described.

[0046] 4 and 5 are sequence diagrams showing the flow of the network construction process of each device in the communication system. In each smart meter 10, the CPU 11 reads a computer program from the ROM 12 or the storage 14, expands it into the RAM 13, and executes it, thereby performing the network construction process shown in FIGS. 4 and 5.

[0047] The sequence diagrams shown in Figures 4 and 5 show the operation of establishing a wireless network by the smart meter 10. The process shown in Figures 4 and 5 is premised on the assumption that none of the smart meters 10 is connected to the base station 20 and no multi-hop wireless communication network has been established.

[0048] First, in step S101, the smart meter 10A is powered on. Then, in step S102, the smart meter 10A activates the second communication unit 18A and starts operating as a slave device (router) of the multi-hop wireless communication network.

[0049] Next, in step S103, the smart meter 10A searches for a predetermined time to see if there is a smart meter 10 serving as a master (coordinator) of a multi-hop wireless communication network in the vicinity. Here, there is no smart meter 10 serving as a master of the multi-hop wireless communication network, so next, in step S104, the smart meter 10A activates cellular communication by the first communication unit 17A, and starts communication with the base station 20 in step S105. Next, in step S106, the base station 20 relays the communication from the smart meter 10A to the server 30 via the WAN line 40.

[0050] Next, in step S107, the smart meter 10A and the HES of the server 30 establish a link via the mobile phone line and the WAN line 40. Then, in step S108, the HES of the server 30 registers information about the metering unit 110A of the smart meter 10A. Then, in step S109, the smart meter 10A starts operating as a master device of the multi-hop wireless communication network. Having started operating as a master device, the smart meter 10A waits for activation of nearby slave devices of the multi-hop wireless communication network.

[0051] After that, in step S110, the smart meter 10B is powered on. Then, in step S111, the smart meter 10B activates the second communication unit 18A and starts operating as a slave unit of the multi-hop wireless communication network.

[0052] Next, in step S112, the smart meter 10B searches for a predetermined time to see if there is a smart meter 10 serving as a master device of a multi-hop wireless communication network in the vicinity. In this case, the smart meter 10A serving as a master device of the multi-hop wireless communication network is present, so in step S113, the smart meter 10B joins as a slave device in the multi-hop wireless communication network in which the smart meter 10A serves as a master device.

[0053] Next, in step S114, the smart meter 10B transmits information about the metering unit 110B of the smart meter 10B to the HES of the server 30 via the second communication unit 18A, the first communication unit 17, and the base station 20 of the smart meter 10A. Then, in step S115, the HES of the server 30 registers the information about the metering unit 110B of the smart meter 10B. Here, the HES of the server 30 stores the downstream communication route to the metering unit 110B of the smart meter 10B in the routing information, with the first communication unit 17A of the smart meter 10A as the destination.

[0054] After that, in step S121, the smart meter 10C is powered on. Subsequently, in step S122, the smart meter 10C activates the second communication unit 18C and starts operating as a slave unit of the multi-hop wireless communication network.

[0055] Next, in step S123, the smart meter 10B searches for a predetermined time to see if there is a smart meter 10 serving as a master device of a multi-hop wireless communication network in the vicinity. Here, since there is a smart meter 10B participating in the multi-hop wireless communication network in which the smart meter 10A serves as a master device, the smart meter 10C participates as a slave device in the multi-hop wireless communication network in which the smart meter 10A serves as a master device in step S124.

[0056] Subsequently, in step S125, the smart meter 10C transmits information about the metering unit 110C of the smart meter 10C to the HES of the server 30 via the second communication unit 18B of the smart meter 10B, the second communication unit 18A and first communication unit 17 of the smart meter 10A, and the base station 20. Then, in step S126, the HES of the server 30 registers the information about the metering unit 110C of the smart meter 10C. Here, the HES of the server 30 stores the downstream communication route to the metering unit 110C of the smart meter 10C in the routing information, with the first communication unit 17A of the smart meter 10A as the destination.

[0057] Similarly, the communication system according to this embodiment is constructed for the smart meters 10D and 10E by repeatedly starting up, searching for the smart meter 10 that is the master, joining the multi-hop wireless communication network, and registering information in the server 30. Fig. 6 is a diagram showing how the smart meters 10A to 10E are started up and a multi-hop wireless communication network is constructed with the smart meter 10A as the master.

[0058] Here, if the smart meter 10D finds three smart meters 10A, 10B, and 10C as connection destinations, it determines which of the three smart meters 10A, 10B, and 10C is the more appropriate connection destination and specifies the connection destination. The smart meter 10D may determine the connection destination based on, for example, the number of hops to the parent smart meter 10, or may determine the connection destination using a determination algorithm weighted by the quality of the multi-hop wireless communication network (for example, error rate, average value of received radio wave strength, etc.). For example, if the communication quality between the smart meter 10D and smart meter 10A, between the smart meter 10D and smart meter 10B, and between the smart meter 10D and smart meter 10C is the same or there is almost no difference, the smart meter 10D may adjust the weighting so that the smart meter 10A with the fewest number of hops is selected as the connection destination.

[0059] In addition, after establishing a link, a smart meter 10 that has joined a multi-hop wireless communication network may search for nearby smart meters 10 at any period, and if a new smart meter 10 has joined the multi-hop wireless communication network, evaluate the communication quality with that smart meter 10 and decide whether to change the connection destination.

[0060] When a multi-hop wireless communication network is constructed in this way, each smart meter 10 participating in the multi-hop wireless communication network transmits metered data to the HES of the server 30 via the parent smart meter 10 (smart meter 10A in the example of FIG. 6). The metered data may include metered values, meter information, and the time of measurement. For example, each smart meter 10 transmits metered data on the amount of power used at regular intervals, triggered by a built-in timer, to the HES of the server 30. The server 30 further transmits the received metered data to a back-end MDMS (Meter Data Management System). The MDMS stores the metered values ​​of the smart meters 10 for each customer.

[0061] The smart meter 10A serving as the master unit activates a mode for transmitting measurement data to the server 30 through the first communication unit 17. Then, the smart meter 10A transmits the measurement data measured by the measurement unit 110A to the server 30 through the first communication unit 17 at a predetermined timing.

[0062] Furthermore, the smart meters 10B to 10E acting as slaves transmit the measurement data from the second communication units 18B to 18E, respectively. When the smart meter 10A acting as the master receives the measurement data from the smart meters 10B to 10E acting as slaves via the second communication unit 18A, the smart meter 10A transmits the measurement data transmitted from the smart meters 10B to 10E to the server 30 via the first communication unit 17. If the usage fee for the mobile phone line depends on the number of communications, the smart meter 10A acting as the master may buffer the transmitted data to reduce the number of transmissions. Reducing the number of transmissions makes it possible to reduce communication costs.

[0063] Each smart meter 10 may check the communication status of the first communication unit 17 and the second communication unit 18, and may appropriately select the optimal communication method or communication partner depending on the communication status. In detail, the smart meter 10 may appropriately select the optimal communication method or communication partner based on the communication error occurrence rate, radio wave strength, etc. of the first communication unit 17 and the second communication unit 18.

[0064] 7 is a diagram showing a state in which the smart meters 10A to 10E are activated and a multi-hop wireless communication network is constructed with the smart meter 10A as the master. In FIG. 7, a change in the wireless communication environment causes frequent communication errors between the smart meters 10B and 10C, so the smart meter 10C switches its connection destination.

[0065] If a communication error occurs between the smart meter 10C and the smart meter 10B, the smart meter 10C performs a connection destination change process in which it performs retransmission an arbitrary number of times and then communicates with another smart meter 10 (for example, smart meter 10D) as a new connection destination.

[0066] The connection destination change process can also be changed from communication using the second communication unit 18 to communication using the first communication unit 17.

[0067] Fig. 8 is a diagram showing a state in which the smart meters 10A to 10E are activated and a multi-hop wireless communication network is established with the smart meter 10A as the master. Fig. 8 shows a state in which, due to a change in the wireless communication environment, communication errors have become frequent between the smart meters 10A and 10E, and so the smart meter 10E switches from communication using the second communication unit 18E to communication using the first communication unit 17E. This occurs, for example, when the smart meters 10D and 10E are located far enough apart that they cannot connect to each other in the 920 MHz band using the second communication units 18D and 18E.

[0068] In this case, when the smart meter 10E is unable to connect to the smart meter 10A using radio waves in the 920 MHz band, it searches for a nearby smart meter 10 that can communicate using radio waves in the 920 MHz band. If there is no smart meter 10 that can communicate using radio waves in the 920 MHz band, the smart meter 10E activates the first communication unit 17E and establishes a link with the server 30 via a mobile communication line.

[0069] If a communication failure occurs in the first communication unit 17 of the smart meter 10 that is the master unit, neither the master unit nor the slave unit will be able to transmit measurement data to the server 30. If a communication failure occurs in the first communication unit 17 of the smart meter 10 that is the master unit, communication can be continued by making another smart meter 10 that is participating in the multi-hop wireless communication network the master unit. In other words, if a communication failure occurs in the first communication unit 17 of the smart meter 10 that is the master unit, that smart meter 10 will be unable to continue functioning as the master unit.

[0070] 9 is a sequence diagram showing the flow of the network construction process of each smart meter 10 in the communication system. In each smart meter 10, the CPU 11 reads a computer program from the ROM 12 or the storage 14, expands it into the RAM 13, and executes it, thereby performing the network construction process shown in FIG.

[0071] The sequence diagram shown in FIG. 9 illustrates the operation of reconstructing the wireless network when a communication failure occurs in the first communication unit 17A of the smart meter 10A that is the master.

[0072] When a communication failure occurs in the first communication unit 17A of the smart meter 10A, in step S131, the smart meter 10A notifies the smart meters 10B to 10E participating in the multi-hop wireless communication network of a restart.

[0073] Subsequently, in step S132, the smart meter 10A executes a reboot of the smart meter 10A itself. After the reboot, subsequently in step S133, the smart meter 10A starts up the second communication unit 18A and starts operating as a slave device (router) of the multi-hop wireless communication network.

[0074] Next, in step S134, the smart meter 10A searches for a predetermined time to see if there is a smart meter 10 serving as a master device (coordinator) of a multi-hop wireless communication network in the vicinity. The smart meter 10A attempts to start the first communication unit 17A and operate as a master device, but is unable to operate as a master device due to a communication failure in the first communication unit 17A. If the smart meter 10A is unable to start the first communication unit 17A for a predetermined period or a predetermined number of times, it may give up operating as a master device and search for a predetermined time to see if there is a smart meter 10 serving as a master device (coordinator) of a multi-hop wireless communication network in the vicinity.

[0075] When the smart meter 10A is restarted due to a communication failure in the first communication unit 17A, the smart meter 10A may set a flag indicating that a communication failure has occurred in the first communication unit 17A before the restart. If the flag is set at the time of the restart, the smart meter 10A may search for a predetermined time to see if there is a smart meter 10 that is a master unit (coordinator) of a multi-hop wireless communication network in the vicinity, without performing a process of activating the first communication unit 17A to start operating as a master unit.

[0076] On the other hand, the smart meter 10B that has received the notification of the restart also restarts its own device in step S135. After the restart, the smart meter 10B subsequently starts up the second communication unit 18B in step S136, and starts operating as a slave device (router) of the multi-hop wireless communication network.

[0077] Next, in step S137, the smart meter 10B searches for a predetermined time to see if there is a smart meter 10 serving as a master (coordinator) of a multi-hop wireless communication network in the vicinity. Here, there is no smart meter 10 serving as a master of the multi-hop wireless communication network, so next, in step S138, the smart meter 10B activates cellular communication by the first communication unit 17B. Next, in step S139, the smart meter 10B starts activation as a master.

[0078] Since the smart meter 10A is connected to the smart meter 10B that is the master of the multi-hop wireless communication network, the smart meter 10A participates as a slave in the multi-hop wireless communication network in which the smart meter 10B is the master in step S140.

[0079] Although not shown in FIG. 9, the smart meters 10C to 10E that have received the notification of restart similarly restart, search for a master unit, and join the multi-hop wireless communication network as a slave unit.

[0080] 10 is a diagram showing a state in which a failure occurs in the first communication unit 17A in a multi-hop wireless communication network in which the smart meter 10A was acting as a master device. When the failure occurs in the first communication unit 17A and the smart meter 10A can no longer continue to function as a master device, the smart meters 10A to 10E participating in the multi-hop wireless communication network execute a restart. Then, the smart meter 10B among the smart meters 10A to 10E becomes the new master device of the multi-hop wireless communication network, and the other smart meters 10 operate as slave devices of the multi-hop wireless communication network.

[0081] In this way, even if a failure occurs in the first communication unit 17A of the smart meter 10A that is the master device of the multi-hop wireless communication network and the smart meter 10A is no longer able to continue functioning as the master device, another smart meter 10 can still operate as the master device.

[0082] 8, if a failure occurs in the first communication unit 17 of the smart meter 10 that is not participating in a multi-hop wireless communication network and is communicating independently with the server 30, and the smart meter 10 is no longer able to communicate with the server 30, the smart meter 10 will again search for a surrounding master unit. If a master smart meter 10 can be found, the smart meter 10 with the failed first communication unit 17 will join the multi-hop wireless communication network in which the discovered smart meter 10 is the master. On the other hand, if a master smart meter 10 cannot be found, the smart meter 10 with the failed first communication unit 17 will continue to operate standalone and periodically search for a surrounding master unit.

[0083] As described above, according to the embodiment of the present invention, there is provided a smart meter 10 that can determine whether to operate as a master device or a slave device in a multi-hop wireless communication network depending on the surrounding environment. The smart meter 10 according to this embodiment can suppress degradation of communication quality and reduce costs required for building and operating the network by determining whether to operate as a master device or a slave device in a multi-hop wireless communication network depending on the surrounding environment.

[0084] In the above embodiments, the network construction process executed by the CPU after reading the software (program) may be executed by various processors other than the CPU. Examples of such processors include programmable logic devices (PLDs) such as field-programmable gate arrays (FPGAs), whose circuit configuration can be changed after fabrication, and application-specific integrated circuits (ASICs), which are dedicated electrical circuits that are processors with circuit configurations specifically designed to execute specific processes. The network construction process may be executed by one of these various processors, or by a combination of two or more processors of the same or different types (e.g., multiple FPGAs, or a combination of a CPU and an FPGA). The hardware structure of these various processors is, more specifically, an electrical circuit that combines circuit elements such as semiconductor devices.

[0085] In addition, in each of the above embodiments, the network construction processing program is described as being pre-stored (installed) in ROM or storage, but this is not limiting. The program may be provided in a form recorded on a non-transitory recording medium such as a CD-ROM (Compact Disk Read Only Memory), a DVD-ROM (Digital Versatile Disk Read Only Memory), or a USB (Universal Serial Bus) memory. The program may also be downloaded from an external device via a network. [Explanation of symbols]

[0086] 10A~10E Smart Meter 20 base station 30 servers 40 WAN lines

Claims

1. a first communication unit that performs cellular wireless communication; a second communication unit that performs wireless multi-hop communication; a search unit that searches for a nearby wireless base station using the first communication unit; a communication control unit that controls connection with a destination device; Equipped with The communication control unit activates the second communication unit at startup, and causes the searching unit to search for a master unit of the multi-hop wireless communication network as a slave unit of the multi-hop wireless communication network, and when a master unit is detected, causes the device to operate as a slave unit of the multi-hop wireless communication network, and when a master unit is not detected, activates the first communication unit to connect to a cellular base station, and causes the device to operate as a master unit of the multi-hop wireless communication network. Wireless communication device.

2. 2. The wireless communication device according to claim 1, wherein the communication control unit causes the search unit to search for another master device in the multi-hop wireless communication network when communication with the master device in the multi-hop wireless communication network becomes impossible.

3. The wireless communication device described in claim 2, wherein if the search unit does not detect a parent device as a result of the search, the communication control unit activates the first communication unit to connect to a cellular base station and operates the device as a parent device of the multi-hop wireless communication network.

4. 2. The wireless communication device according to claim 1, wherein when communication with the base station becomes impossible, the communication control unit notifies a restart instruction to a slave device of the multi-hop wireless communication network from the second communication unit, and then restarts the wireless communication device itself.

5. The wireless communication device described in claim 4, wherein the communication control unit attempts to operate the device as a parent device of the multi-hop wireless communication network after restarting the device, and if the device is unable to operate as a parent device for a predetermined period of time or a predetermined number of times, causes the search unit to search for a parent device of the multi-hop wireless communication network as a child device of the multi-hop wireless communication network.

6. The wireless communication device described in claim 4, wherein the communication control unit sets a predetermined flag before restarting the device, and if the flag is set after restarting the device, does not attempt to operate as a parent device of the multi-hop wireless communication network, but instead causes the search unit to search for a parent device of the multi-hop wireless communication network as a child device of the multi-hop wireless communication network.

7. The wireless communication device according to any one of claims 1 to 6, wherein the communication control unit causes the search unit to search at a predetermined period to determine whether there is a device that has newly joined the multi-hop wireless communication network.

8. The wireless communication device according to claim 7, wherein, when a device that has newly joined the multi-hop wireless communication network is found as a result of the search by the search unit, the communication control unit determines whether to change the connection destination of the multi-hop communication to the newly joined device.

9. The wireless communication device according to any one of claims 1 to 8, further comprising a metering unit that measures data relating to the amount of power used in the location where the wireless communication device is installed.

10. The processor: At the time of startup, a second communication unit that performs wireless multi-hop communication is started, and the second communication unit is made to search for a master unit of the multi-hop wireless communication network as a slave unit of the multi-hop wireless communication network; When a master unit is detected, the device operates as a slave unit of the multi-hop wireless communication network; If the parent device is not detected, the first communication unit for performing cellular wireless communication is activated to connect to a cellular base station, and the device operates as a parent device of the multi-hop wireless communication network. A wireless communication method for performing processing.

11. On the computer, At the time of startup, a second communication unit that performs wireless multi-hop communication is started, and the second communication unit is made to search for a master unit of the multi-hop wireless communication network as a slave unit of the multi-hop wireless communication network; When a master unit is detected, the device operates as a slave unit of the multi-hop wireless communication network; If the parent device is not detected, the first communication unit for performing cellular wireless communication is activated to connect to a cellular base station, and the device operates as a parent device of the multi-hop wireless communication network. A computer program that executes a process.

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