JP6587175B2 - Multi-hop communication system, communication apparatus, and communication method - Google Patents

Description

  The present invention relates to a multi-hop communication system used for power line carrier communication and the like, and a communication apparatus and a communication method used in the multi-hop communication system.

  Conventionally, a multi-hop communication system constructed by a power line carrier communication terminal is known. Such a power line carrier communication terminal is, for example, in accordance with G3-PLC which is a communication protocol for power line carrier communication. Power line carrier communication based on 9903 is performed (see Patent Document 1).

International Publication No. 2014/125816

  In the multi-hop communication system as described above, when data is transmitted from one slave unit to another slave unit, it is basically via the master unit. However, in such a system, there is a problem that communication traffic increases by going through the parent device.

  The present invention provides a multi-hop communication system capable of suppressing communication traffic.

  A multi-hop communication system according to an aspect of the present invention is a multi-hop communication system in which slave units communicate with each other using a master unit as a relay station, the master unit, a first slave unit, a second slave unit, and A plurality of slave units including a third slave unit, wherein the first slave unit includes a storage unit storing route information indicating a route for communication, and the second slave unit, Based on the communication unit that receives data addressed to the third slave unit and the route information stored in the storage unit, (i) when the predetermined information is not included in the data received by the communication unit, The communication unit transmits the data to an adjacent child device on a first route from the first child device toward the parent device, and (ii) the predetermined information is received in the data received by the communication unit. Is included, the first child device is directed from the first child device to the third child device. Towards handset adjacent on the second route not passing through the base unit a route, and a control unit for transmitting the data to the communication unit.

  The multi-hop communication system of the present invention can suppress communication traffic.

FIG. 1 is a network configuration diagram of a multi-hop communication system according to Embodiment 1. FIG. 2 is a block diagram illustrating a functional configuration of the multi-hop communication system according to the first embodiment. FIG. 3 is a sequence diagram showing transmission / reception of a Hello packet between the node N0 and the node N1. FIG. 4A is a first diagram illustrating a node table of the node N1. FIG. 4B is a diagram illustrating a node table of the node N0. FIG. 4C is a second diagram illustrating the node table of the node N1. FIG. 5A is a diagram illustrating a data structure of a Hello packet. FIG. 5B is a diagram illustrating a data structure of a subpacket included in a Hello packet. FIG. 6 is a diagram showing details of the node table. FIG. 7 is a flowchart of relay processing in the multi-hop communication system according to the first embodiment. FIG. 8 is a diagram showing header information.

  Hereinafter, embodiments will be described with reference to the drawings. It should be noted that each of the embodiments described below shows a comprehensive or specific example. The numerical values, shapes, materials, constituent elements, arrangement positions and connecting forms of the constituent elements, steps, order of steps, and the like shown in the following embodiments are merely examples, and are not intended to limit the present invention. In addition, among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims indicating the highest concept are described as optional constituent elements.

  Each figure is a schematic diagram and is not necessarily shown strictly. Moreover, in each figure, the same code | symbol is attached | subjected to substantially the same structure, and the overlapping description may be abbreviate | omitted or simplified.

(Embodiment 1)
[Constitution]
First, the configuration of the multi-hop communication system according to Embodiment 1 will be described. FIG. 1 is a network configuration diagram of a multi-hop communication system according to Embodiment 1. FIG. 1 shows a logical configuration (logical topology) of each node, and does not show a physical configuration.

  In the multi-hop communication system 10 shown in FIG. 1, a master-slave type communication network is constructed with the node N0 as a parent node and the nodes N1 to N6 as child nodes. The multi-hop communication system 10 includes a concentrator 20 that is a device corresponding to the node N0 and a plurality of smart meters 21 to 26 that are devices corresponding to the nodes N1 to N6. Note that the number given to the link connecting the nodes is a link cost to be described later.

  The concentrator 20 is a server (computer) that collects power usage from a plurality of smart meters 21 to 26. The concentrator 20 is operated by an electric power company or a service provider that manages electric power usage and supports power saving on behalf of the electric power company. The concentrator 20 operates as a parent device in the multi-hop communication system 10.

  Note that the concentrator 20 is not necessarily realized by a single computer, and may be realized by a plurality of computers. For example, the concentrator 20 may be configured by a management server and a plurality of relay devices.

  Each of the smart meters 21 to 26 is a meter that is provided in a consumer and measures the amount of power used by the consumer. Smart meters 21 to 26 operate as slave units in multihop communication system 10.

  In addition, the smart meters 21 to 26 are not limited to the mode of measuring the usage amount of power, and may use the usage amount of infrastructure resources such as the usage amount of tap water or the usage amount of gas. Further, the number of smart meters included in the multi-hop communication system 10 is an example, and is not particularly limited.

  Moreover, although the consumer in which each of the smart meters 21-26 is provided is a dwelling unit of an apartment house, for example, it is not specifically limited. The consumer may be, for example, a detached house, an office, or a factory.

  The concentrator 20 and the smart meters 21 to 26 perform power line communication (PLC: Power Line Communications) that transmits a signal using a power line as a transmission medium. Similarly, one smart meter performs power line carrier communication with another smart meter.

  Next, the functional configuration of the multihop communication system 10 will be described. FIG. 2 is a block diagram illustrating a functional configuration of the multihop communication system 10. In FIG. 2, only the smart meter 21 among the plurality of smart meters is illustrated, but the other smart meters have the same configuration as the smart meter 21 and are not illustrated.

  First, the configuration of the concentrator 20 will be described. As shown in FIG. 2, the concentrator 20 includes a parent device communication unit 31, a parent device control unit 32, and a parent device storage unit 33.

  The parent device communication unit 31 is a communication interface for communicating with the child device communication unit 34 included in the smart meters 21 to 26 via the power line 50. The base unit communication unit 31 is specifically a communication module (communication circuit) used for power line carrier communication, and receives measurement data of power usage based on the control of the base unit control unit 32.

  The base unit control unit 32 is a control device that controls the base unit communication unit 31. For example, the base unit control unit 32 acquires measurement data of power usage from the smart meter 21 through the base unit communication unit 31. The acquired measurement data is stored in the parent device storage unit 33. Specifically, the base unit control unit 32 is a processor that executes a control program stored in the base unit storage unit 33, but may be realized by a microcomputer, a dedicated circuit, or the like.

  The base unit storage unit 33 is a storage device that stores a control program executed by the base unit control unit 32, measurement data of power usage of the smart meters 21 to 26, and the like. The base unit storage unit 33 stores a node table and a route table.

  The node table (adjacent node table) is a table for managing information of the adjacent smart meter (or concentrator 20). The route table is information indicating a combination of the destination smart meter and route information (all smart meters that relay until reaching the destination smart meter or one hop ahead smart meter terminal), and is referred to as route information at the time of packet transmission Is done.

  Specifically, the parent device storage unit 33 is realized by, for example, a hard disk and a semiconductor memory.

  Next, the smart meter 21 will be described. As shown in FIG. 2, the smart meter 21 includes a slave unit communication unit 34, a measurement data acquisition unit 35, a slave unit control unit 36, and a slave unit storage unit 37. The smart meter 21 is an example of a communication device used in the multihop communication system 10.

  The slave unit communication unit 34 is a communication interface for communicating with the master unit communication unit 31 or the slave unit communication unit 34 included in the smart meters 22 to 26 via the power line 50. Specifically, the slave unit communication unit 34 is a communication module (communication circuit) used for power line carrier communication, and receives measurement data of power usage based on the control of the slave unit control unit 36.

  The measurement data acquisition unit 35 is an interface that acquires measurement data of power usage from a measurement device (not shown) that measures power usage. Specifically, the measurement data acquisition unit 35 is, for example, a terminal to which a measurement device is wired. The measurement data acquisition unit 35 may acquire measurement data from the measurement device by wireless communication or optical communication. In this case, the measurement data acquisition unit 35 is specifically a communication module (communication circuit) for wireless communication or a light receiving sensor.

  The subunit | mobile_unit control part 36 is a control apparatus which controls the subunit | mobile_unit communication part 34, for example, transmits the measurement data which the measurement data acquisition part 35 acquired through the subunit | mobile_unit communication part 34. FIG. Specifically, the slave unit control unit 36 is a processor that executes a control program stored in the slave unit storage unit 37, but may be realized by a microcomputer, a dedicated circuit, or the like.

  The slave unit storage unit 37 is a storage device that stores a control program executed by the slave unit control unit 36, a node table, a route table, and the like. Specifically, the child device storage unit 37 is realized by, for example, a semiconductor memory.

[basic action]
Next, the basic operation of the multi-hop communication system 10 will be described with reference to FIG. In the following description of the basic configuration, the node N0 is specifically the concentrator 20, and the nodes N1 to N6 are smart meters 21 to 26, respectively.

  As described above, the communication network shown in FIG. 1 is a master-slave type communication network in which the node N0 is a parent node and the nodes N1 to N6 are child nodes. In a master-slave type communication network, one end of a route for transmitting data (data packet) is basically a node N0 which is a parent node, and the other ends of the route for transmitting data are nodes N1 to N6. Become one. Communication data transmitted from one child node is relayed by another child node as necessary and transmitted to the parent node.

  Here, in the following description, a node closer to the parent node in the logical topology than a single node is expressed as a node higher than the single node. Further, a node farther from the parent node on the logical topology than a single node is expressed as a node lower than the single node. A node that can communicate directly with one node without passing through another node is expressed as a node adjacent to the one node (adjacent node of the one node). In other words, a node adjacent to one node is a node located at the first hop from one node on the logical topology.

  In a multi-hop communication network, each node does not know a node that can communicate directly without relay until a node table and a route table (route information) are stored in the storage unit of the node. Therefore, in order to search for an adjacent node, a Hello packet is broadcast.

  In a master-slave type communication network, transmission of a Hello packet is started from a parent node. In the example of FIG. 1, first, when the node N0 broadcasts the Hello packet and the adjacent nodes N1 and N2 receive the Hello packet transmitted by the node N0, each of the nodes N1 and N2 stores the link cost. . Here, the link cost is an evaluation value of communication quality between two nodes capable of direct communication, and is used for determining a route in the communication network. The higher the link cost, the worse the communication quality.

  The link cost may change depending on which node is set as a transmission side between two nodes capable of direct communication. For this reason, the link cost according to the reception strength of the signal from the partner node is called the reception link cost, and the link cost obtained according to the reception strength when the signal from the own node is received by the counterpart node is referred to as the transmission link cost Call. In other words, the reception link cost is an evaluation value of communication quality (reception quality) on the reception side, and the transmission link cost is an evaluation value of communication quality (transmission quality) on the transmission side. Finally, the larger one of the reception link cost and the transmission link cost is used as the link cost. In the storage unit of each node, the reception link cost and the transmission link cost are stored as a node table in association with the address of the counterpart node.

  Here, processing for determining the link cost will be described with reference to the drawings. FIG. 3 is a sequence diagram showing transmission / reception of a Hello packet between the node N0 and the node N1. 4A and 4C are diagrams illustrating the node table of the node N1, and FIG. 4B is a diagram illustrating the node table of the node N0. Note that the node tables shown in FIGS. 4A to 4C include upper cost and route cost, which will be described later.

  As illustrated in FIG. 3, when the node N0 transmits the Hello packet H1, the node N1 receives the Hello packet H1, and calculates a reception link cost according to the reception quality of the Hello packet H1. The received link cost calculated by the node N1 is stored in association with 0 which is the address of the node N0 in the node table of the node N1 shown in FIG. 4A. The receiving link cost here is 11.

  Next, the node N1 transmits a Hello packet H2 including the address of the node N0 that is the transmission source of the Hello packet H1 and the reception link cost. The node N0 that has received the Hello packet H2 calculates the reception link cost when the signal from the node N1 is received by the Hello packet H2, and as shown in FIG. 4B, the calculated reception link cost is used as the address of the node N1. Is stored in the node table in association with “1”. The receiving link cost here is 5.

  The Hello packet H2 includes the address of the node N0 and the reception link cost when the node N1 receives the Hello packet H1. Therefore, the node N0 stores the received link cost included in the Hello packet H2 as the transmission link cost from the node N0 to the node N1 in the node table in association with the address of the node N0. That is, as shown in FIG. 4B, the transmission link cost from the node N0 to the node N1 is 11.

  Thereafter, the node N0 transmits the Hello packet H3 again. The Hello packet H3 includes the received link cost when the Hello packet H2 is received from the node N1 and the address of the node N1. Therefore, the node N1 can acquire the transmission link cost when the Hello packet H2 is transmitted to the node N1 by receiving the Hello packet H3. The transmission link cost from the node N1 to the node N0 is 5. As shown in FIG. 4C, the node N1 stores the received link cost received from the node N0 as a transmission link cost from the node N1 to the node N0 in association with the address of the node N0 in the node table.

  As described above, the Hello packets H1 to H3 are transmitted and received between the adjacent node N0 and the node N1, so that each of the node N0 and the node N1 can store the reception link cost and the transmission link cost. Further, after transmission / reception of the Hello packets H1 to H3, the contents of the node table of the adjacent nodes are complementary. That is, even if one content is lost, the other content can be restored. Similarly, the Hello packet is transmitted and received between the node N0 and the node N2, and each of the node N0 and the node N2 stores the reception link cost and the transmission link cost.

  When the node N1 and the node N2 store the transmission link cost, the node N1 and the node N2 broadcast a Hello packet. Since the node N0 already stores the reception link cost and the transmission link cost, the node N0 does not respond to the broadcast-transmitted Hello packet, but the nodes N3 and N5 respond to the Hello packet broadcast-transmitted by the node N1. By repeating such an operation sequentially, the nodes N1 to N6 store the reception link cost and the transmission link cost between adjacent nodes.

  More specifically, the Hello packet includes the address and link cost of the node included in the route to the node N0. Here, a detailed data structure of the Hello packet will be described. FIG. 5A is a diagram illustrating a data structure of a Hello packet. FIG. 5B is a diagram illustrating a data structure of a subpacket included in a Hello packet.

  As illustrated in FIG. 5A, the Hello packet includes an SID that is an address of a transmission source node, a TY that indicates the type of the packet, and an NC that indicates the type of the transmission source node. In addition, the Hello packet includes any one of the subpacket SB1, the subpacket SB2, and the subpacket SB3 depending on the type of the Hello packet (which one of H1 to H3 in FIG. 3). . Specifically, the Hello packet H1 includes a subpacket SB1, the Hello packet H2 includes a subpacket SB2, and the Hello packet H3 includes a subpacket SB3. In the Hello packet, TY is a value indicating the Hello packet, and NC is a value indicating the parent node or a value indicating the child node.

  The subpacket SB1 includes the number of hops of the route formed when the transmission source node communicates with the parent node N0 (that is, the number of nodes included in the route to the node N0) and the route. The node address and the link cost information between a plurality of nodes included in the route are included. Therefore, the lower nodes N1 to N6 that have received the Hello packet H1 can know the upper cost (route cost from the parent node to the upper adjacent node).

  The subpacket SB2 includes information on the destination address and link cost (transmission link cost of the partner node). The subpacket SB3 includes the address of the destination node and the link cost (transmission link cost of the partner node).

  As shown in FIG. 5B, each subpacket specifically includes a subpacket type STY for distinguishing the three types of subpackets, the number of nodes LN included in the subpacket, and the subpacket. The address NID and link cost LC of each included node are included. That is, the format of the subpacket is variable length.

  Thus, the Hello packet H1 includes the address and link cost of the node included in the route from the transmission source node to the node N0. Therefore, the node that has received the Hello packet H1 can store the address and link cost of the node included in the route from the transmission source node to the node N0 in the node table. FIG. 6 is a diagram showing details of the node table. FIG. 6 shows details of the node table of the node N6 as an example.

  As shown in FIG. 6, in the node table, the node address (NID) and link cost (LC) included in the route from the node N0 to the source node of the Hello packet H1 are stored as higher costs. The The higher cost is stored for each node of the transmission source of the Hello packet H1, and is stored for each of the node N3 and the node N5 in the example of FIG. In the node table, the sum of the link costs included in the route from the node N0 to the node that received the Hello packet H1 is stored as the route cost. The route cost is also stored for each source node of the Hello packet H1.

  For example, the node N6 selects a route having the minimum route cost. In the example of FIG. 6, the node N6 selects a route associated with N5. In this way, a tree-type topology network is constructed by each node selecting one upper adjacent node.

  The selected route is notified to the node N0 as topology notification information (hereinafter also referred to as a topology notification packet), and the node N0 can obtain the route information to the node N6. Although the topology notification information may be transmitted in a timely manner, it is normally transmitted periodically at regular time intervals.

[Relay processing]
Thus, in the multi-hop communication system 10, each node knows at least the route from the node to the parent node. That is, a route table including a route from the smart meter to the concentrator 20 is stored in the child device storage unit 37 included in each smart meter.

  Therefore, for example, when the smart meter 25 transmits measurement data to the concentrator 20, the smart meter 25 refers to the route table in the child device storage unit 37 of the smart meter 25 and is adjacent on the route to the concentrator 20. The measurement data is unicast transmitted to the smart meter 21 that is the node to be operated. The smart meter 21 receives this measurement data, refers to the route table in the slave unit storage unit 37 of the smart meter 21, and unicasts the measurement data to the concentrator 20 that is an adjacent node on the route to the concentrator 20. Send. Thereby, the concentrator 20 can memorize | store the measurement data of the consumer with which the smart meter 25 was provided in the main | base station memory | storage part 33. FIG.

  By the way, in order to perform DR (Demand Response) control in cooperation with a plurality of consumers, communication may be performed between smart meters provided in each consumer. Here, the concentrator 20 knows the route to each smart meter 21 to 26 in order to obtain the topology notification information from each smart meter 21 to 26, but each smart meter 21 to 26 is connected to other smart meters. You don't always know the route.

  Therefore, in the multi-hop communication system 10, even if the destination of data transmitted from one smart meter is another smart meter, the data is basically relayed to the concentrator 20 which is a parent device. Then, it is further relayed to the destination smart meter. For example, when the smart meter 25 wants to transmit data to the smart meter 24, the data is basically transmitted through a route of N5 → N1 → N0 → N1 → N4.

  However, in this case, in order to reduce communication traffic, it is desirable that data is transmitted through a route of N5 → N1 → N4.

  Therefore, in the multi-hop communication system 10, when the smart meter 25 wants to transmit data to the smart meter 24 without going through the concentrator 20, the data includes predetermined information in the data. When the smart meter 21 receives data including predetermined information from the smart meter 25, the smart meter 21 searches the route that does not pass through the concentrator 20 with reference to the child device storage unit 37 of the smart meter 21, and is included in the searched route. Data is transmitted to the smart meter 24 which is an adjacent node.

  Such relay processing will be described with reference to FIG. FIG. 7 is a flowchart of relay processing in the multi-hop communication system 10. In the following description, it is assumed that the smart meter 21 relays data received from the smart meter 25 as an example. In the following description of FIG. 7, each constituent element (slave unit communication unit 34, slave unit control unit 36, and slave unit storage unit 37) is a constituent element of the smart meter 21 unless otherwise specified. Suppose there is.

  First, the slave unit communication unit 34 of the smart meter 21 receives data addressed to the smart meter 24 from the smart meter 25 (S10). The data is data unicasted toward the smart meter 21. The subunit | mobile_unit control part 36 of the smart meter 21 determines whether predetermined | prescribed information is contained in the received data (S11).

  When the predetermined information is not included in the data received by the slave unit communication unit 34 in step S10 (No in S11), the slave unit control unit 36 moves from the smart meter 21 to the concentrator 20 to the slave unit communication unit 34. Data is transmitted toward an adjacent node on the first route (S12). In this case, handset communication unit 34 unicasts data to concentrator 20.

  On the other hand, when the predetermined information is included in the data received by the slave unit communication unit 34 in step S10 (Yes in S11), the slave unit control unit 36 stores the second route in the slave unit storage unit 37. It is determined whether or not (S13). More specifically, the child device control unit 36 stores a route table in which the second route toward the smart meter 24 and not toward the concentrator 20 is stored in the child device storage unit 37 in the child device storage unit 37. It is determined whether or not included.

  When the second route is included in the route table in the child device storage unit 37 (Yes in S13), the child device control unit 36 sends data to the child device communication unit 34 toward an adjacent node on the second route. Transmit (S14). In this case, handset communication unit 34 unicasts data to smart meter 24. When a plurality of second routes are included, the child device control unit 36 selects, for example, the second route with the lowest route cost.

  When the second route is not included in the route table in the child device storage unit 37, the child device control unit 36 causes the child device communication unit 34 to transmit data to an adjacent node on the first route (S12). ). That is, the slave unit communication unit 34 transmits data to the concentrator 20.

  The predetermined information may be in any form, for example, header information such as a mesh header described later.

  As described above, the multi-hop communication system 10 is a multi-hop communication system based on communication between slave units using the master unit as a relay station. The multi-hop communication system 10 includes a concentrator 20 and a plurality of smart meters 21 to 26.

  For example, the smart meter 21 includes a slave unit storage unit 37 that stores a route table indicating a route for communication, a slave unit communication unit 34 that receives data addressed to the smart meter 24 from the smart meter 25, and a slave unit. And a control unit 36.

  The smart meter 21 is an example of a first slave unit, the smart meter 25 is an example of a second slave unit, and the smart meter 24 is an example of a third slave unit. The subunit | mobile_unit memory | storage part 37 is an example of a memory | storage part, the subunit | mobile_unit communication part 34 is an example of a communication part, and the subunit | mobile_unit control part 36 is an example of a control part. The route table is an example of route information, and the route information is information corresponding to at least a part of the route table.

  Based on the route table stored in the child device storage unit 37, the child device control unit 36 (i) when the data received by the child device communication unit 34 does not include predetermined information, the smart meter 21 sends the concentrator 20. The slave unit communication unit 34 transmits the data to an adjacent node (in this case, the concentrator 20) on the first route toward the destination. When the adjacent node on the first route is a smart meter, the slave unit control unit 36 causes the slave unit communication unit 34 to transmit the data to the smart meter.

  On the other hand, the slave unit control unit 36 is a second route from the smart meter 21 to the smart meter 24 and does not pass through the concentrator 20 when the predetermined information is included in the data received by the slave unit communication unit 34. The slave unit communication unit 34 transmits the data to the smart meter 24 adjacent on the route.

  With such a configuration, the multi-hop communication system 10 can suppress communication traffic when the slave unit transmits data including predetermined information. The effect of suppressing communication traffic is particularly noticeable when the number of nodes included in the multi-hop communication system 10 is large (the number of hops is large).

  In addition, since it can be realized by adding predetermined information to a conventional data format, it can be easily introduced using a conventional multi-hop communication system. According to the configuration in which the predetermined information is added to the conventional data format, in the operation of the conventional multi-hop communication system (operation in which the slave units use the master unit as a relay station), the data amount is the same as the conventional one. There is an advantage that communication can be performed without increasing the amount of data.

  Note that the slave unit control unit 36 is a case where the data received by the slave unit communication unit 34 includes predetermined information, and the slave unit storage unit 37 does not store route information indicating the second route. In this case, the slave unit communication unit 34 transmits the data to the node (here, the concentrator 20).

  Thereby, the slave unit control unit 36 is a case where the data received by the slave unit communication unit 34 includes predetermined information, and the slave unit storage unit 37 stores route information indicating the second route. If not, communication can be performed using the first route.

[Example 1 of route acquisition method]
As described above, in order to communicate using the second route, it is necessary that the route table includes the second route. Here, any method may be used as a method for storing route information (a part of the route table) indicating the second route in the child device storage unit 37. Hereinafter, a method in which one smart meter acquires route information (second route) from the smart meter to another smart meter will be exemplified.

  As described above, the route information may be included in, for example, a Hello packet transmitted from an upper node (or lower node). That is, in this case, each of the plurality of smart meters transmits a Hello packet including route information indicating a route from the smart meter to the concentrator 20. For example, in the smart meter 21, when the handset communication unit 34 receives a Hello packet, the handset controller 36 stores route information included in the Hello packet in the handset storage unit 37.

  If such route information is used, the smart meter 21 can transmit data to the smart meter (node) included in the route information without passing through the concentrator 20.

  In the smart meter 21, when the slave unit communication unit 34 receives a Hello packet, the slave unit control unit 36 is included in the Hello packet when the reception link cost of the Hello packet is equal to or higher than a predetermined threshold. You may memorize | store route information in the subunit | mobile_unit memory | storage part 37. FIG. In other words, when the slave unit communication unit 34 receives a Hello packet, the slave unit control unit 36 stores the route information included in the Hello packet in the slave unit when the reception link cost of the Hello0 packet is less than a predetermined value. It may not be stored in the unit 37. The reception link cost is an example of reception quality.

  As a result, route information indicating a route with good reception quality is stored in the handset storage unit 37, so that the handset controller 36 can select a route with good reception quality.

  In the smart meter 21, the Hello packet received by the slave communication unit 34 may further include the transmission link cost of the smart meter 21. Examples of such Hello packets include the above-described Hello packet H2 and Hello packet H3. The transmission link cost is an example of transmission quality.

  In this case, the slave unit control unit 36 determines that the received Hello packet has a reception link cost that is equal to or higher than a predetermined threshold and the transmission link cost included in the Hello packet is equal to or higher than the predetermined threshold. The route information included in the packet is stored in the child device storage unit 37.

  As a result, route information indicating a route with good reception quality and transmission quality is stored in the child device storage unit 37, so that the child device control unit 36 can select a route with good reception quality and transmission quality.

  In the smart meter 21, when route information indicating the route between the smart meter 21 and the smart meter 24 is stored in the child device storage unit 37, the child device control unit 36 is adjacent to the child device communication unit 34. If communication with the smart meter 24 fails for a predetermined number of times, route information indicating a route between the smart meter 21 and the smart meter 24 may be deleted from the slave device storage unit 37.

  Specifically, the handset controller 36 determines that the communication has failed, for example, when there is no response to the transmitted Hello packet or when an error response is received. The predetermined number of times may be determined in any way.

  Thereby, route information indicating a route that cannot be used can be deleted, and the storage capacity of the child device storage unit 37 can be secured.

  In smart meter 21, slave unit communication unit 34 may further receive a topology notification packet including route information. In this case, in the smart meter 21, when the handset communication unit 34 receives the topology notification packet, the handset controller 36 may store the route information included in the topology notification packet in the handset storage unit 37. . The topology notification packet is a packet for one smart meter to notify route information from the smart meter to the concentrator 20 to the concentrator 20 or the entire network.

  Thereby, the subunit | mobile_unit control part 36 can select a route | root using the route information contained in a topology notification packet.

  In the smart meter 21, the route information stored in the child device storage unit 37 may be deleted by the child device control unit 36 when a predetermined period has elapsed since the last use. Thereby, the route information that is not used can be deleted, and the storage capacity of the child device storage unit 37 can be secured. The predetermined period may be determined in any way.

[Example 2 of route acquisition method]
When data (data packet) is transmitted from one smart meter to another smart meter, a mesh header and a source route header may be added to the data as header information. In such a case, route information can be stored using the source route header as follows. FIG. 8 is a diagram showing header information. The source route header is information for instructing the smart meter of the transmission destination when returning data from the concentrator 20.

  For example, when data is transmitted from the smart meter 25 (node N5) to the smart meter 23 (node N3), the header information of the data transmitted from the smart meter 25 is as shown in FIG. The source address “5” (node N5) and the destination address “3” (node N3) are assigned.

  Here, as described above, the smart meter 25 stores the route to the concentrator 20 in the child device storage unit 37 of the smart meter 25. Therefore, the smart meter 25 transmits data to which the header information shown in FIG. 8A is added to the adjacent smart meter 21 on the route from the smart meter 25 to the concentrator 20.

  The smart meter 21 that has received the data to which the header information shown in (a) of FIG. 8 has been received, uses the address “1” of the smart meter 21 (node N1) as the source as shown in (b) of FIG. It is given to the route header. Then, the smart meter 21 transmits data to which the header information shown in (b) of FIG.

  As described above, the concentrator 20 stores a route to each smart meter. Therefore, the concentrator 20 adds the addresses “0”, “1”, and “3” of the nodes included in the route to the smart meter 23 to the source route header, as shown in FIG.

  Here, the concentrator 20 detects that the address “1” is duplicated when the addresses “0”, “1”, and “3” are added to the source route header. That is, when the concentrator 20 transmits data from the smart meter 25 to the smart meter 23, the concentrator 20 recognizes that the data transmitted from the smart meter 25 may be returned by the smart meter 21 instead of being returned by the concentrator 20. To do. In other words, it is not necessary to relay data in the order of “N5 → N3 → N1 → N0 → N1 → N3”, and it is recognized that data should be relayed in the order of “N5 → N3 → N1 → N3”. To do.

  Accordingly, as shown in FIG. 8D, the concentrator 20 generates a source route header from which the redundant route 60 is removed, and stores data including the generated source route header as header information in the smart meter 21. Send.

  Then, the smart meter 21 can store the route “N5 → N3 → N1 → N3” specified by the source route header included in the received data in the slave unit storage unit 37 of the smart meter 21. Therefore, the slave unit control unit 36 of the smart meter 21 can use the route “N5 → N3 → N1 → N3” in the subsequent data relay. For example, the handset controller 36 of the smart meter 21 can use the route “N5 → N3 → N1 → N3” as the second route.

  As described above, the concentrator 20 receives data to the smart meter 23 transmitted from the smart meter 25 via the smart meter 21, and transmits the data to the smart meter 23 via the smart meter 21. When doing so, the data including the source route header indicating the route from the smart meter 25 to the smart meter 23 after being folded back by the smart meter 21 is transmitted. In this case, each of the smart meter 21, the smart meter 25, and the smart meter 23 is an example of a first slave unit, a second slave unit, and a third slave unit. The source route header is an example of first route information.

  When the slave unit communication unit 34 of the smart meter 21 receives data including the source route header, the slave unit control unit 36 uses the source route header as a part of the route table (first route information), for example. The second route is specified using the route table (source route header) stored in the device storage unit 37 and stored in the child device storage unit 37.

  Thereby, the subunit | mobile_unit control part 36 of the smart meter 21 can memorize | store the route | root from which the redundant route was removed by the concentrator 20 in the subunit | mobile_unit memory | storage part 37. FIG.

  Finally, the smart meter 21 transmits data to the smart meter 23 according to the source route header. Then, the smart meter 23 can store the route “N5 → N3 → N1 → N3” specified by the source route header included in the received data in the child device storage unit 37 of the smart meter 23. That is, when the smart meter 23 receives data including the source route header, the smart meter 23 can store the source route header as a part of the route table (first route information).

  Therefore, the handset controller 36 of the smart meter 23 can use the route “N5 → N3 → N1 → N3” in the subsequent data relay.

  For example, when the smart meter 23 transmits data to the smart meter 25, the smart meter 23 may transmit the data by designating the route “N5 → N3 → N1 → N3”. That is, the smart meter 23 may transmit data addressed to the smart meter 25 including the designation of the route indicated by the source route header.

  In this way, by specifying a route with a smart meter that is a transmission source (a smart meter that is a starting point of transmission), it is possible to reduce processing in the smart meter that performs relaying. Note that such a route designation may be performed by a smart meter that performs relay. In this case, the processing of the smart meter that relays after the smart meter is reduced.

  The data structure using the mesh header and the source route header as described above is an example. For example, the contents of the mesh header may be included in the source route header. In addition, the route notification may be performed by another data configuration.

[Modification]
By the way, in the multi-hop communication system 10, each node can recognize that communication with a node that can communicate directly with one hop away from the node has failed. It is impossible to recognize whether or not (relay) has failed.

  For example, in FIG. 1, the smart meter 26 can recognize a communication failure with the smart meter 23, the smart meter 24, and the smart meter 25, but the data transmitted by the smart meter 26 by the smart meter 21 two hops away. Even if the relay fails, the failure cannot be recognized.

  Therefore, if the slave unit control unit 36 of the smart meter 21 fails to relay the data transmitted by the smart meter 25 that is two or more hops away from the plurality of smart meters 21 to 26, the slave unit communication unit 34 Information indicating failure of relay may be transmitted to the smart meter 25. Specifically, the information indicating the failure of relay is a data packet of a route error.

  As a result, the smart meter 25 can recognize whether or not the smart meter 21 that is two hops away and cannot communicate directly fails.

(Other embodiments)
The multihop communication system 10 according to Embodiment 1 has been described above, but the present invention is not limited to the above embodiment.

  For example, in the above embodiment, power line carrier communication is performed in the multi-hop communication system, but the present invention is also applicable to other communication methods such as wireless communication. That is, the present invention may be realized as a multi-hop communication system that uses a communication device other than a smart meter and performs communication other than power line carrier communication.

  In the above embodiment, the present invention is realized as a multi-hop communication system that constructs a tree-type network topology. Here, specifically, such a multi-hop communication system is ITU-T G.264. This is a multi-hop communication system that constructs a tree-type network topology based on 9905. Such a multi-hop communication system is applied to, for example, a smart meter or a BEMS (Building Energy Management System). The present invention can also be applied to communication systems using other proactive routing protocols.

  In the above embodiment, each component may be configured by dedicated hardware or may be realized by executing a software program suitable for each component. Each component may be realized by a program execution unit such as a CPU or a processor reading and executing a software program recorded on a recording medium such as a hard disk or a semiconductor memory.

  Each component may be a circuit. These circuits may constitute one circuit as a whole, or may be separate circuits. Each of these circuits may be a general-purpose circuit or a dedicated circuit.

  Moreover, in the said embodiment, another process part may perform the process which a specific process part performs. Further, the order of the plurality of processes may be changed, and the plurality of processes may be executed in parallel.

  The comprehensive or specific aspect of the present invention may be realized by a system, a method, an integrated circuit, a computer program, or a recording medium such as a computer-readable CD-ROM. The system, method, integrated circuit, computer You may implement | achieve with arbitrary combinations of a program or a recording medium. For example, the present invention may be realized as a communication device (child device) included in a multi-hop communication system, or may be realized as a program installed in the communication device.

  As described above, the multi-hop communication system according to one or more aspects has been described based on the embodiment, but the present invention is not limited to this embodiment. Unless it deviates from the gist of the present invention, various modifications conceived by those skilled in the art have been made in this embodiment, and forms constructed by combining components in different embodiments are also within the scope of one or more aspects. May be included.

10 Multi-hop communication system 20 Concentrator
21-26 Smart meter (slave device, communication device)
34 Slave unit communication unit (communication unit)
36 Remote control unit (control unit)
37 Slave unit storage unit (storage unit)

Claims (13)

A multi-hop communication system in which slave units communicate with each other using the master unit as a relay station,
With the parent machine,
A plurality of slave units including a first slave unit, a second slave unit, and a third slave unit,
The first slave unit is
A storage unit for storing route information indicating a route for communication;
A communication unit that receives data addressed to the third slave unit from the second slave unit;
Based on the route information stored in the storage unit, (i) when the data received by the communication unit does not include predetermined information, the first route from the first slave unit to the master unit (Ii) when the predetermined information is included in the data received by the communication unit from the first slave unit to the third slave unit, A multi-hop communication system comprising: a control unit that causes the communication unit to transmit the data toward an adjacent child device on a second route that is directed to the child device and does not pass through the parent device. Each of the plurality of slave units transmits a Hello packet including route information indicating a route from the slave unit to the master unit,
The multi-hop communication system according to claim 1, wherein when the communication unit receives the Hello packet, the control unit stores route information included in the Hello packet in the storage unit. The said control part memorize | stores the route information contained in the said Hello packet in the said memory | storage part, when the said communication part receives the said Hello packet, when the reception quality of the said Hello packet is more than a predetermined threshold value. The multihop communication system according to 2. The Hello packet received by the communication unit further includes the transmission quality of the first slave unit,
The controller includes a route included in the Hello packet when the received quality of the Hello packet is equal to or higher than a predetermined threshold and the transmission quality included in the Hello packet is equal to or higher than a predetermined threshold. The multihop communication system according to claim 2, wherein information is stored in the storage unit. The communication unit further receives a topology notification packet including route information,
The multi-hop communication system according to claim 1, wherein, when the communication unit receives the topology notification packet, the control unit stores route information included in the topology notification packet in the storage unit. The master unit is a case where data addressed to the third slave unit transmitted by the second slave unit is received via the first slave unit, and the data is received by the first slave unit. A first route indicating a route from the second child device to the third child device by returning to the data from the second child device when transmitting to the third child device via the machine Send information,
When the communication unit receives data including the first route information, the control unit stores the first route information in the storage unit, and uses the first route information stored in the storage unit. The multi-hop communication system according to claim 1, wherein the second route is specified. The third handset is
When the data including the first route information is received, the first route information is stored,
The multi-hop communication system according to claim 6, wherein data destined for the second slave unit including a route designation indicated by the first route information is transmitted. When the communication unit fails to communicate with the second slave unit a predetermined number of times or more, the control unit obtains route information including a route between the first slave unit and the second slave unit. The multi-hop communication system according to any one of claims 1 to 7. When the control unit fails to relay data from a slave unit that is more than 2 hops away from the plurality of slave units, the control unit transmits information indicating the relay failure to the slave unit. The multi-hop communication system according to any one of claims 1 to 8. When the predetermined information is included in the data received by the communication unit, and when the route information indicating the second route is not stored in the storage unit, the control unit The multihop communication system according to any one of claims 1 to 9, wherein the data is transmitted to the communication unit toward a child device adjacent on a route.   The communication apparatus which operate | moves as a 1st subunit | mobile_unit with which the multihop communication system of any one of Claims 1-10 is provided. In a multi-hop communication system comprising a parent device and a plurality of child devices including a first child device, a second child device, and a third child device, a communication method executed by the first child device. And
A receiving step of receiving data addressed to the third slave unit from the second slave unit;
Based on the route information stored in the storage unit included in the first slave unit, (i) when the received data does not include predetermined information, the first slave unit is directed to the master unit. (Ii) when the predetermined data is included in the received data, the data is transmitted from the first slave unit to the third slave unit. A communication method for transmitting the data to an adjacent slave unit on a second route that is not routed through the master unit.   A program for causing a computer to execute the communication method according to claim 12.

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