JP6671039B2 - Communication device, multi-hop communication system, and communication method - Google Patents

Description

  The present invention relates to a multi-hop communication system, and a communication device and a communication method used in the multi-hop communication system.

  2. Description of the Related Art Conventionally, a multi-hop communication system in which a slave communicates with a master using another slave as a relay station has been known. Patent Literature 1 discloses, as a multi-hop communication system, an ad hoc network system that can prevent an enormous amount of route information.

JP 2013-005043 A

  In a multi-hop communication system, when a link that cannot communicate on a communication route occurs, the communication route needs to be reconfigured.

  The present invention provides a multi-hop communication system, and a communication device and a communication method used in a multi-hop communication system, which can reconfigure a communication route when a link that cannot communicate on the communication route occurs. I do.

  A communication device according to an aspect of the present invention is a communication device that operates as the master device among a master device and a plurality of slave devices, forming a communication route for performing multi-hop communication, wherein the plurality of child devices The device includes a first child device, and a second child device that is one hop farther from the parent device than the first child device on the communication route, and the communication device includes the plurality of child devices. Each of the plurality of sub-units is route information associated only with a higher-level sub-unit that is one hop closer to the main unit than the sub-unit on the communication route among the plurality of sub-units, and A storage unit in which route information indicating a route is stored, and a communication between the first communication device and the higher-level communication device closer to the master device than the first communication device on the communication route by one hop is impossible. When it is detected that there is, corresponding to the second slave unit in the route information And a control unit for changing the vignetting the upper handset.

  A multi-hop communication system according to an aspect of the present invention includes a master unit and a plurality of slave units that constitute a communication route for performing multi-hop communication, and the plurality of slave units include a first slave unit and A second hop that is one hop farther from the master than the first slave on the communication route, wherein the master is configured such that each of the plurality of slaves is the plurality of slaves. Among the route information associated with only the upper handset which is one handset closer to the master unit than the slave unit on the communication route, wherein the route information indicating the communication route is stored. Part, when it is detected that communication between the upper communication device and the first slave unit that is closer to the master unit by one hop than the first slave unit on the communication route is impossible, Change the upper child device associated with the second child device in the information And a control unit.

  The communication device according to one aspect of the present invention operates as a slave provided in the multi-hop communication system.

  A communication method according to an aspect of the present invention is a communication method executed by a multi-hop communication system, wherein the multi-hop communication system forms a communication route for performing multi-hop communication, and includes a master device and a plurality of child devices. Machine, the plurality of slaves include a first slave, and a second slave that is one hop farther from the master than the first slave on the communication route, The master unit is such that each of the plurality of slave units is associated with only a higher-order slave unit that is one hop closer to the master unit than the slave unit on the communication route, among the plurality of slave units. A storage unit storing route information indicating the communication route, the communication method comprising: a higher-level communication device that is one hop closer to the master device than the first slave device on the communication route; Communication with the first slave unit is not possible When detecting the changes the upper handset associated with the second handset of the route information.

  A program according to one embodiment of the present invention is a program for causing a computer to execute the communication method.

  According to the multi-hop communication system of the present invention, and the communication device and the communication method used in the multi-hop communication system of the present invention, when a link that cannot communicate on a communication route occurs, the communication route is reconfigured. can do.

FIG. 1 is a network configuration diagram of the multi-hop communication system according to the first embodiment. FIG. 2 is a block diagram showing a functional configuration of the multi-hop communication system according to Embodiment 1. FIG. 3 is a sequence diagram showing transmission and reception of Hello packets between the nodes N0 and N1. FIG. 4A is a first diagram illustrating the node table of the node N1. FIG. 4B is a diagram showing a node table of the node N0. FIG. 4C is a second diagram illustrating the node table of the node N1. FIG. 5 is a diagram illustrating an example of the route information. FIG. 6 is a flowchart of updating the route information in the multi-hop communication system 100. FIG. 7 is a diagram illustrating the updated route information. FIG. 8 is a diagram illustrating route information updated based on the operation example 3. FIG. 9 is a diagram illustrating route information updated based on the operation example 4. FIG. 10 is a diagram illustrating a network configuration of the multi-hop communication system according to the fifth operation example. FIG. 11 is a diagram illustrating route information updated based on the operation example 5. FIG. 12A is a diagram illustrating an example of the topology notification information. FIG. 12B is a diagram illustrating another example of the topology notification information. FIG. 12C is a diagram illustrating still another example of the topology notification information.

  Hereinafter, embodiments will be described with reference to the drawings. Each of the embodiments described below shows a comprehensive or specific example. Numerical values, shapes, materials, constituent elements, arrangement positions and connection forms of constituent elements, steps, order of steps, and the like shown in the following embodiments are merely examples and do not limit the present invention. In addition, among the components in the following embodiments, components not described in the independent claims indicating the highest concept are described as arbitrary components.

  Each drawing is a schematic diagram, and is not necessarily strictly illustrated. In each of the drawings, substantially the same components are denoted by the same reference numerals, and redundant description may be 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 the multi-hop communication system according to the first embodiment. FIG. 2 is a block diagram showing a functional configuration of the 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 100 shown in FIG. 1, a master-slave communication network having a node N0 as a parent node and nodes N1 to N10 as child nodes is constructed. In a master-slave communication network, a parent node generally manages routes (route information) to a plurality of child nodes, and each of the plurality of child nodes manages at least a route to the parent node. In the following embodiments, the node N0 is also described as a parent device N0, and the nodes N1 to N10 are also described as child devices N1 to N10.

  As shown in FIG. 2, the multi-hop communication system 100 includes a master unit N0 and a plurality of slave units N1 to N10. Note that the number of slave units included in the multi-hop communication system 100 is not particularly limited.

  In FIG. 2, only the slave N1 among the plurality of slaves is illustrated in detail, and the slave N1 is mainly described below. However, other slaves included in the multi-hop communication system 100 are described. N2 to N10 have the same configuration as the slave unit N1.

  First, the configuration of master unit N0 will be described. The master unit N0 is an example of a communication device that operates as a master unit included in the multi-hop communication system 100, and includes a first communication unit 11, a first control unit 12, and a first storage unit 13. The master unit N0 acquires (aggregates) data from a plurality of slave units included in the multi-hop communication system 100 and manages the acquired data, for example.

  The first communication unit 11 is a communication interface for communicating with the second communication unit 21 provided in the slave unit (for example, the slave unit N1). The first communication unit 11 is specifically a communication module (communication circuit).

  The first communication unit 11 broadcasts a Hello packet under the control of the first control unit 12, for example.

  The Hello packet is a packet (signal) that is broadcast-transmitted every predetermined period in order to notify another communication device that the communication device that transmits the Hello packet is in a communicable state (alive). It is. The predetermined period is, for example, 10 seconds.

  The communication performed by the first communication unit 11 and the second communication unit 21 may be any wired or wireless communication, and is not particularly limited. For example, the first communication unit 11 and the second communication unit 21 perform power line communication (PLC: Power Line Communication), but may perform wired communication using a wired LAN. In addition, the first communication unit 11 and the second communication unit 21 communicate with each other using a specific low-power wireless communication, a wireless communication using a communication standard such as ZigBee (registered trademark), Bluetooth (registered trademark), or Wi-Fi (registered trademark). Communication may be performed.

  The first control unit 12 is an example of a control unit. The first control unit 12 is a control device that controls the first communication unit 11, and receives data from the slave unit N1 or the slave unit N2 through the first communication unit 11, for example. In addition, the first control unit 12 causes the first communication unit 11 to transmit a Hello packet, an encryption key described later, and the like. The first control unit 12 is, specifically, a processor that executes a control program stored in the first storage unit 13, but may be realized by a microcomputer, a dedicated circuit, or the like.

  The first storage unit 13 is an example of a storage unit. The first storage unit 13 stores a control program executed by the first control unit 12, route information indicating a route from the master unit N0 to each of a plurality of slave units included in the multi-hop communication system 100, and the like. Device. The first storage unit 13 is realized by, for example, a semiconductor memory.

  Next, the slave unit N1 will be described. The slave N1 is an example of a communication device that operates as a slave included in the multi-hop communication system 100, and includes a second communication unit 21, a second control unit 22, and a second storage unit 23.

  The second communication unit 21 is an example of a communication unit. The second communication unit 21 is a communication interface for communicating with the first communication unit 11 or the second communication unit 21 provided in another slave unit. The second communication unit 21 is, specifically, a communication module (communication circuit) of the same type as the first communication unit 11. The second communication unit 21 broadcasts a Hello packet based on the control of the second control unit 22, for example. Further, the second communication unit 21 receives a Hello packet from the parent device N0 or another child device.

  The second control unit 22 is an example of a slave unit control unit. The second control unit is a control device that controls the second communication unit 21. For example, it causes the second communication unit 21 to transmit data and Hello packets. The second control unit 22 is, specifically, a processor that executes a control program stored in the second storage unit 23, but may be realized by a microcomputer, a dedicated circuit, or the like.

  The second storage unit 23 is a storage device that stores a control program executed by the second control unit 22, a node table, a route table, and the like. The second storage unit 23 is specifically realized by, for example, a semiconductor memory or the like.

  The node table (adjacent node table) is a table that manages information on the adjacent child device (or the parent device N0). The route table is information indicating a route to the parent device N0 (at least a node closer to the one-hop parent device N0 than the child device), and is referred to when transmitting data (data packet).

[basic action]
Next, the basic operation of the multi-hop communication system 100 will be described with reference to FIG.

  As described above, the communication network shown in FIG. 1 is a master-slave communication network in which the node N0 is a parent node and the nodes N1 to N10 are child nodes. In the master-slave communication network, one end of a data transmission route is a node N0, and the other end of the data transmission route is any of the nodes N1 to N10. 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 on the logical topology than one node is expressed as a node higher than the one node. Further, a node farther from the parent node in the logical topology than one node is expressed as a node lower than the one node. Further, a node that can directly communicate with one node without passing through another node is expressed as a node adjacent to the one node (adjacent node of the one node). A node adjacent to one node is, in other words, a node located at the first hop from the one node on the logical topology.

  In a multi-hop communication network, each node does not know neighboring nodes that can communicate directly without relaying until a node table or a route table is stored in the storage unit of the node. Therefore, a Hello packet is broadcast transmitted to search for an adjacent node.

  In a master-slave 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 a 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 a communication network. The link cost indicates, for example, that the larger the value, the worse the communication quality.

  The link cost may change between two nodes capable of direct communication depending on which node is the transmitting side. 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 partner node receives the signal from the own node is called the transmission link cost. Call. The reception link cost is, in other words, an evaluation value of communication quality (reception quality) on the reception side, and the transmission link cost is, in other words, an evaluation value of communication quality (transmission quality) on the transmission side. Ultimately, the larger of the received link cost and the transmitted 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 partner node. The method of determining the link cost is not limited to such an example. For example, the reception cost may be directly used as the link cost.

  Here, the processing for determining the link cost will be described with reference to the drawings. FIG. 3 is a sequence diagram showing transmission and reception of Hello packets between the nodes N0 and 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 higher-order costs and route costs, and the contents of these will be described later.

  As shown in FIG. 3, when the node N0 transmits the Hello packet H1, the node N1 receives the Hello packet H1, and calculates the reception link cost according to the reception quality of the Hello packet H1. The reception link cost calculated by the node N1 is stored in association with “N0” which is the address of the node N0 in the node table of the node N1 illustrated in FIG. 4A. The reception 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 a signal from the node N1 is received by the Hello packet H2, and as shown in FIG. 4B, calculates the reception link cost as the address of the node N1. Is stored in the node table in association with “N1”. The reception 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 reception 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 reception link cost when the Hello packet H2 is received from the node N1, and the address of the node N1. Therefore, by receiving the Hello packet H3, the node N1 can acquire the transmission link cost when transmitting the Hello packet H2 to the node N0. The transmission link cost from the node N1 to the node N0 is 5. As shown in FIG. 4C, the node N1 stores the reception link cost received from the node N0 as the 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, by transmitting and receiving the Hello packets H1 to H3 between the adjacent nodes N0 and N1, each of the nodes N0 and N1 can store the reception link cost and the transmission link cost. After the transmission and reception of the Hello packets H1 to H3, the contents of the node tables of the adjacent nodes have complementary contents. That is, even if one content is lost, the other content can be restored. Similarly, the Hello packet is transmitted and received between the nodes N0 and N2, and the nodes N0 and N2 store the reception link cost and the transmission link cost, respectively.

  When the nodes N1 and N2 store the transmission link costs, the nodes N1 and N2 broadcast and transmit Hello packets. The node N0 does not respond to the broadcast-transmitted Hello packet because the reception link cost and the transmission link cost are already stored, but the nodes N3 and N6 respond to the broadcast-transmitted Hello packet by the node N1. By repeating such operations sequentially, the nodes N1 to N10 store the reception link cost and the transmission link cost between the adjacent nodes.

  More specifically, the Hello packet also includes the address and link cost of a node included in the route to the node N0. Therefore, each of the nodes N1 to N10 can store the address and the link cost of the node included in the route from the transmission source node to the node N0 in the node table.

  Then, each of the nodes N1 to N10 selects, for example, a route having the minimum route cost to the node N0, and stores the route as a route table. The route table stores the addresses of all nodes through which data passes until the data arrives at the destination slave unit in the selected route, and the case where only the addresses of higher-order adjacent nodes in the selected route are stored. However, in the first embodiment, only the address of the upper adjacent node in the selected route is stored.

  As described above, each of the nodes N1 to N10 selects one higher-order adjacent node, thereby constructing a tree-type topology network (a set of solid-line links shown in FIG. 1) as shown in FIG. Is done. In the following embodiments, a tree topology network is also referred to as a communication route. The broken line shown in FIG. 1 is an unused link that can communicate but is not included in the communication route.

  On the other hand, the node N0 can obtain the node table and the route table by receiving the topology notification information from each of the nodes N1 to N10. The topology notification information may be transmitted in a timely manner, but is normally transmitted at regular time intervals.

[Operation Example 1]
As described above, the first control unit 12 of the master unit N0 (node N0) is configured to determine which of the slave units (nodes N1 to N10) is adjacent to one of the slave units (where one slave unit corresponds to which slave unit). Can be directly communicated) can be stored in the first storage unit 13. That is, the first control unit 12 can recognize that there is an unused link indicated by a broken line in FIG.

  Further, the first control unit 12 can store the constructed communication route in the first storage unit 13 as route information based on the topology notification information received by the first communication unit 11. Here, in the route information of the master unit N0, each of the plurality of slave units is only a higher-order slave unit that is one hop closer to the master unit N0 than the slave unit on the communication route among the slave units. Are associated. FIG. 5 is a diagram illustrating an example of the route information.

  When transmitting data to the slave N6, the first control unit 12 refers to the route information stored in the first storage unit 13 and specifies that the upper node of the slave N6 is the slave N1. Next, the first control unit 12 refers to the route information stored in the first storage unit 13, and there is no upper child device associated with the specified child device N1 (the higher node is the parent device N0). Identify that. As described above, by using the route information illustrated in FIG. 5, the first control unit 12 can specify the route to the destination child device.

  By the way, in the communication route shown in FIG. 1, when the master unit N0 and the slave unit N1 cannot communicate with each other, the master unit N0 generally changes the communication route by changing the link destination of the slave unit N1. Reconfigure. For example, when the slave unit N1 and the slave unit N2 can communicate with each other (when the slave unit N2 is an adjacent node of the slave unit N1), the link L1 is not used, and instead, the slave unit N1 and the slave unit N1 are used. A link L2 connecting to N2 is used. At this time, the first control unit 12 of the master unit N0 changes the higher-order slave unit associated with the slave unit N1 to the slave unit N2 in the route information stored in the first storage unit 13.

  On the other hand, in the multi-hop communication system 100, when the master unit N0 and the slave unit N1 cannot communicate with each other, the master unit N0 is located farther from the slave unit N1 than the slave unit N1 on the communication route. By changing the higher-level slave (link destination) associated with N3, the route information is updated to reconfigure the communication route. FIG. 6 is a flowchart of updating the route information in the multi-hop communication system 100. FIG. 7 is a diagram illustrating the updated route information.

  As shown in FIG. 6, first, the first control unit 12 of the master unit N0 detects that the master unit N0 and the slave unit N1 cannot communicate with each other (S11). The parent device N0 is an example of a higher-level communication device, and the child device N1 is an example of a first child device.

  For example, when the first communication unit 11 of the master unit N0 transmits data to the slave unit N1, when a response (ACK) to the data transmitted by the first communication unit 11 to the slave unit N1 cannot be received, The one control unit 12 can determine (detect) that the link L1 between the master unit N0 and the slave unit N1 is disconnected and the master unit N0 and the slave unit N1 cannot communicate with each other.

  Also, when the topology notification information from the child device N1 (or the child device N3, the child device N4, and the child device N5) periodically transmitted to the parent device N0 is received without passing through the link L1, The first control unit 12 can determine (detect) that the link L1 between the master unit N0 and the slave unit N1 is disconnected and the master unit N0 and the slave unit N1 cannot communicate with each other.

  As a result of the detection as described above, the first control unit 12 changes the higher-level child device associated with the child device N3 in the route information stored in the first storage unit 13 (S12). Specifically, as shown in FIG. 7, the first control unit 12 changes the higher-level child device associated with the child device N3 from the child device N1 to the child device N2. That is, in the communication route shown in FIG. 1, the link L3 connecting the slave unit N1 and the slave unit N3 is unused, and the link L4 connecting the slave unit N2 and the slave unit N3 is used instead. . The slave N3 is an example of a second slave.

  Thereby, the first control unit 12 can reconfigure the communication route (route information) when a link that does not allow communication between the slave units occurs on the communication route. Specifically, the first control unit 12 performs communication even when a slave unit with which the slave unit N1 can communicate is not on the communication route (in the example of FIG. 1, when there is no unused link L2). Routes can be reconfigured.

  In addition, when the first control unit 12 further detects that communication between the master unit N0 and the slave unit N1 is impossible, the first control unit 12 excludes the slave unit N3 other than the slave unit N3 having the slave unit N1 as an upper slave unit in the route information. The higher-level child device of another child device may be changed. Here, as shown in FIGS. 1 and 7, the other handset other than handset N3 having handset N1 as the upper handset is specifically handset N6. The first control unit 12 changes the higher-level child device associated with the child device N6 in the route information stored in the first storage unit 13 to the child device N3. That is, in the communication route shown in FIG. 1, the link L5 connecting the slave unit N1 and the slave unit N6 is unused, and the link L6 connecting the slave unit N3 and the slave unit N6 is used instead. .

  Thereby, the first control unit 12 can also change the higher-level child device of the child device N6 other than the child device N3 in addition to the child device N3 having the child device N1 as the higher-level child device. That is, two higher-level slave units included in the route information can be changed by one detection.

  In addition, as for the change of the higher-level slave unit associated with the slave unit N3 as described above, the first controller 12 determines that the communication between the master unit N0 and the slave unit N1 is not possible and that the slave unit N1 This may be performed when it is detected that a child device other than the communicable higher-level communication device is not included in the plurality of child devices (when the link L1 is disconnected and the link L2 does not exist in FIG. 1). In other words, as in the example of FIG. 1, when the first control unit 12 cannot communicate with the master unit N0 and the slave unit N1, and when the slave unit N1 can communicate with the slave unit N2, Alternatively, a higher-order slave unit associated with the slave unit N1 instead of the slave unit N3 may be changed. In other words, the change of the upper child device of the child device N1 (first child device) and the change of the higher child device of the child device N3 (second child device) enable the child device N1 to communicate with the child device N2. It may be selectively performed based on whether or not.

  Further, when the first control unit 12 changes the upper child device associated with the child device N3, when there are a plurality of child devices that are candidates for the higher child device (child devices that the child device N3 can directly communicate with). Can be considered. For example, in the example of FIG. 1, since the slave N3 can directly communicate with the slave N6 in addition to the slave N2, the first control unit 12 can also select the slave N6 as an upper slave.

  In such a case, the first control unit 12 may select, as a higher-level child device of the child device N3, a child device having the lowest route cost from the parent device N0 among a plurality of candidate child devices. Alternatively, among the plurality of candidate slaves, the slave having the smallest hop count from the master N0 may be selected as the upper slave of the slave N3. As described above, the first control unit 12 may select a higher-order slave unit from a plurality of candidate slave units based on a predetermined selection criterion.

[Operation Example 2]
In the above-described operation example 1, the method of updating the route information when the master unit N0 and the slave unit N1 cannot communicate with each other has been described. However, the same updating method is used when the slave units cannot communicate with each other. Can be used. Hereinafter, the description will be continued with reference to FIG.

  For example, when the slave unit N1 and the slave unit N3 cannot communicate with each other, first, the first control unit 12 of the master unit N0 detects that the slave unit N1 and the slave unit N3 cannot communicate. .

  For example, when the first communication unit 11 of the master unit N0 transmits data to the slave unit N3, the data should originally arrive at the slave unit N3 via the slave unit N1. However, when the slave unit N1 and the slave unit N3 cannot communicate with each other, that is, when the link L3 is disconnected, the slave unit N1 responds (ACK) to the data transmitted to the slave unit N3 from the slave unit N3. Cannot be received.

  Then, information indicating that slave unit N1 could not communicate with slave unit N3 (failure to receive ACK) is transmitted to master unit N0. When the first communication unit 11 of the master unit N0 receives such information from the slave unit N1, the first control unit 12 of the master unit N0 disconnects the link L3 between the slave unit N1 and the slave unit N3, and It can be determined (detected) that N1 and the slave unit N3 cannot communicate with each other.

  Also, the case where the topology notification information from the slave unit N3 (or the slave unit N4 or the slave unit N5), which is periodically transmitted to the master unit N0, is received by the first communication unit 11 without passing through the link L3. The first control unit 12 can determine (detect) that the link L3 between the slave unit N1 and the slave unit N3 has been disconnected and the slave unit N1 and the slave unit N3 cannot communicate with each other.

  As a result of the detection as described above, the first control unit 12 changes the higher-level child device associated with the child device N4 in the route information stored in the first storage unit 13. Specifically, the first control unit 12 changes the higher-level child device associated with the child device N4 from the child device N3 to the child device N6. That is, in the communication route shown in FIG. 1, the link L7 connecting the slave unit N3 and the slave unit N4 is not used, and the link L8 connecting the slave unit N4 and the slave unit N6 is used instead. .

  Thereby, the first control unit 12 can reconfigure the communication route (route information) when a link that does not allow communication between the slave units occurs on the communication route. Specifically, the first control unit 12 is configured to operate when the slave unit with which the slave unit N3 can communicate is not on the communication route (in FIG. 1, the unused link L4 and the unused link L6 do not exist). Can also reconfigure the communication route.

[Operation example 3]
As in the first operation example, a communication route is configured as shown in FIG. 1, route information as shown in FIG. 5 is stored in the first storage unit 13, and the master unit N0 and the slave unit N1 can communicate with each other. A situation that disappears is conceivable.

  In such a situation, the first control unit 12 normally changes the higher-level slave unit associated with the slave unit N1 to the slave unit N3 among the route information stored in the first storage unit 13. Absent. This is because the child device N1 is a higher-level child device of the child device N3, so that a route loops between the child device N1 and the child device N3.

  However, as described above, in the multi-hop communication system 100, when the master unit N0 and the slave unit N1 cannot communicate with each other, the master unit N0 is closer to the one-hop master unit N0 than the slave unit N1 on the communication route. The route information is updated by changing the higher-level slave (link destination) associated with the remote slave N3. Then, since the child device N1 is no longer a higher-level child device of the child device N3, even if the higher-level child device associated with the child device N1 is changed to the child device N3, a communication between the child device N1 and the child device N3 occurs. Routes do not loop.

  Therefore, the first control unit 12 may change the higher-level child device associated with the child device N1 from the route information stored in the first storage unit 13 to the child device N3. FIG. 8 is a diagram showing route information updated based on such an operation example 3. When the route information is updated from the state of FIG. 5 to the state of FIG. 8, the link L1 is not used in FIG. 1 and the link L4 is used instead.

  As described above, when the first control unit 12 detects that communication between the master unit N0 and the slave unit N1 is impossible, the first control unit 12 sends the route information stored in the first storage unit 13 to the slave unit N3. It is also possible to change the associated upper child device and change the upper child device associated with the child device N1 in the route information to the child device N3.

  This can increase the possibility that the communication route can be reconfigured. The update of the route information is performed, for example, when the first control unit 12 detects that a slave other than the slave N3 with which the slave N1 can communicate is not included in the multi-hop communication system 100. It is good to be performed. That is, the first control unit 12 may change the higher-level slave associated with the slave N1 to the slave N3 when it is unavoidable that the slave N3 is set as a higher-level slave of the slave N1. . The detection that the slave unit other than the slave unit N3 with which the slave unit N1 can communicate is not included in the multi-hop communication system 100 is performed by, for example, referring to the node table stored in the first storage unit 13.

[Operation Example 4]
Further, in the same situation as in the operation example 1 and the operation example 3, the upper child device of the child device N3 is changed to the child device N4 having the child device N3 as the upper child device, and the upper child device of the child device N4 is further changed. May be. That is, when the first control unit 12 detects that communication between the master unit N0 and the slave unit N1 is not possible, the first control unit 12 assigns the higher-order slave unit associated with the slave unit N3 in the route information to the slave unit N4. And the higher-level child device associated with the child device N4 in the route information may be changed.

  In this case, the first control unit 12 can first generate a route from the child device N4 to the child device N0, assuming that the higher-level child device associated with the child device N3 has been changed to the child device N4. It is determined whether or not. Then, when it is determined that there is a route from the child device N4 to the child device N0, the first control unit 12 changes the higher-level child device associated with the child device N3 to the child device N4 in the route information. Then, the higher-level child device associated with the child device N4 in the route information is changed. Note that the higher-level child device associated with the child device N4 is specifically changed to the child device N9. FIG. 9 is a diagram showing route information updated based on such an operation example 4. When the route information is updated from the state of FIG. 5 to the state of FIG. 9, the link L3 is not used in FIG. 1, and the link L9 is used instead.

  This can increase the possibility that the communication route can be reconfigured. In addition, such update of the route information may include, for example, that the first control unit 12 does not include the slaves other than the slaves N1 and N4 with which the slave N3 can communicate, in the multi-hop communication system 100. It may be performed when it is detected. That is, the first controller 12 may change the higher-level slave associated with the slave N3 to the slave N4 when it is unavoidable that the slave N4 is set as the higher-level slave of the slave N3. . The detection that the slave N3 and the slave other than the slave N3 with which the slave N3 can communicate is not included in the multi-hop communication system 100 refers to, for example, a node table stored in the first storage unit 13. Done by

[Operation example 5]
In Operation Example 5, an operation example in the multi-hop communication system 100 having a network configuration different from that in FIG. 1 will be described. FIG. 10 is a diagram illustrating a network configuration of the multi-hop communication system 100 according to the fifth operation example. Note that the broken lines shown in FIG. 10 are unused links that can be communicated but are not included in the communication route.

  In the network configuration as shown in FIG. 10, when the master unit N0 and the slave unit N1 cannot communicate with each other, the first control unit 12 is farther from the one-hop master unit N0 than the slave unit N1 on the communication route. The higher-level child device (child device N1) associated with the child device N2 cannot be changed. This is because the slave N2 cannot communicate with slaves other than the slave N1. The slave unit N2 can communicate with the slave unit N3, but if the slave unit higher than the slave unit N2 is set to the slave unit N3, the slave unit N2 is the upper slave unit of the slave unit N3. Route loops. For this reason, the slave unit N3 is excluded from the candidates for the higher-order slave unit to be changed.

  In such a case, the first control unit 12 determines whether it is possible to change the higher-level child device of the child device N3 farther from the one-hop parent device N0 than the child device N2. In the example of FIG. 10, the slave unit N3 cannot communicate with slave units other than the slave unit N2 (and the slave unit N4 excluded from the candidates for the higher-order slave unit to which the slave unit N3 is changed). Then, the first control unit 12 determines whether or not it is possible to change the higher-level child device of the child device N4 farther from the one-hop parent device N0 than the child device N3.

  Here, the child device N4 can communicate with the child device N7 in addition to the child device N3. Thus, the first control unit 12 changes the higher-level child device associated with the child device N4 from the child device N3 to the child device N7 in the route information. FIG. 11 is a diagram showing route information updated based on such an operation example 5.

  As described above, when the first control unit 12 determines that it is impossible to change the upper slave unit associated with the slave unit N2, the first control unit 12 determines that the lower slave unit N2 is farther from the master unit N0 than the slave unit N2 on the communication route. A determination is made as to whether or not the slave units (the slave units N3 and N4) are the target lower-order slave units capable of changing the upper-order slave unit associated with the lower-order slave unit. The process is performed in order from the device (in the order of N3 and N4) until a target lower-order child device is found. Then, the first control unit 12 changes the upper child device associated with the child device N4, which is the lower child device determined to be the target lower child device, in the route information.

  This can increase the possibility that the communication route can be reconfigured. The determination as to whether or not the child device is a target lower-order child device is made by, for example, referring to a node table stored in the first storage unit 13. The determination as to whether or not the child device is the target child device is simply made based on whether one child device can communicate with another child device (that is, based on the presence or absence of an unused link). However, even if one slave unit can communicate with another slave unit, if the communication quality between the one slave unit and the other slave unit does not reach a certain standard, one slave unit is disconnected. It is not necessary to judge the target lower handset. The determination as to whether or not it is the target lower handset may be made in consideration of not only whether communication is possible but also communication quality. In the case where the candidate for the upper slave unit to be changed is connected to the disconnected link, such a candidate for the upper slave unit is excluded and it is determined whether or not it is the target lower slave unit. May be.

[Operation example 6]
As described above, in the multi-hop communication system 100, in the same situation as the operation example 1, the operation example 3, and the operation example 4, the first control unit 12 sets the upper slave unit of the slave unit N3 and the slave unit N6. To change.

  Here, the first control unit 12 may change the upper-level slave based on the number of hops from the master N0 to the slave N3.

  For example, the first control unit 12 may change the upper child device associated with the child device N3 in the route information from the child device N3 to the parent device N0 when the candidate child device included in the plurality of child devices is changed. The number of hops. Then, in the change of the higher-level slave unit associated with the slave unit N3 in the route information, the first control unit 12 identifies a candidate slave unit whose specified hop number is equal to or less than the hop number before the change. The changed slave unit may be prioritized over the candidate slave unit in which the changed hop number is larger than the hop number before the change.

  As a result, an increase in the number of hops from the child device N3 to the parent device N0 due to the change of the upper child device of the child device N3 is suppressed.

[Operation Example 7]
As described above, in the multi-hop communication system 100, in the same situation as the operation example 1, the operation example 3, and the operation example 4, the first control unit 12 sets the upper slave unit of the slave unit N3 and the slave unit N6. To change.

  Here, for example, in addition to the change of the slave unit N3, the first control unit 12 also changes the higher-order slave unit with respect to the slave units N4 and N5, which are lower-order slave units than the slave unit N3. You may. The slaves N4 and N5 are slaves farther from the master N0 than the slave N3 on the communication route, and communicate with the master N0 via the slave N3. That is, the slave N3 is an example of a second slave, and in this case, each of the slave N4 and the slave N5 is an example of a fourth slave.

  Similarly, for example, in addition to the change of the child device N6, the first control unit 12 also ranks the child device N7, child device N8, and child device N10, which are lower child devices than the child device N6. The slave unit may be changed. The child device N7, the child device N8, and the child device N10 are child devices farther from the parent device N0 than the child device N6 on the communication route, and transmit and receive information to and from the parent device N0 via the child device N6. Machine. That is, in this case, the slave N6 is an example of a second slave, and each of the slave N7, the slave N8, and the slave N10 is an example of a fourth slave.

  At this time, the first control unit 12 changes the higher-level child device of the child device N4, the child device N5, the child device N7, the child device N8, and the child device N10 in addition to the child device N3 and the child device N6. Is also good. In other words, the first control unit 12 reviews the higher-order slaves of the slaves N4, N5, N7, N8, and N10 in addition to the slaves N3 and N6. May be performed.

  For example, when the upper child device of the child device N3 is changed, there is a possibility that a more optimal upper child device exists for the child device N4 and the child device N5 than at present. Similarly, when the upper child device of the child device N6 is changed, there is a possibility that a more optimal upper child device exists for the child device N7, the child device N8, and the child device N10 than at present.

  Therefore, when the higher-level slave unit of the slave unit N3 is changed, the first controller 12 replaces the higher-order slave units associated with the slave units N4 and N5 in the route information with, for example, a route cost (link cost). ) To make changes. The link cost is an example of communication quality information indicating the communication quality between two slave units included in the multi-hop communication system 100, and is stored in the first storage unit 13 in the form of a node table and a route table. In addition, as the communication quality information, a reception strength or the like may be used.

  Similarly, when the higher-level child device of the child device N6 is changed, the first control unit 12 determines the higher-level child device associated with the child device N7, the child device N8, and the child device N10 in the route information, for example, , May be changed based on the link cost.

  In addition, the first control unit 12 outputs all of the child device N4, the child device N5, the child device N7, the child device N8, and the child device N10, that is, the disconnected link, in addition to the child device N3 and the child device N6. The upper child device of all the child devices related to L1 may be changed, or only some of the child devices related to the disconnected link L1 may be selectively changed to the higher child device.

  For example, the first control unit 12 associates only the child device whose route cost to the parent device N0 is equal to or more than a predetermined value due to the change of the higher-level child device associated with the child device N3. The higher-level slave unit may be changed.

  In the example of FIG. 1, in a state where the higher-level slave unit associated with the slave unit N3 has been changed, the route cost from the master unit N0 to the slave unit N4 is less than a predetermined value, and the route cost from the master unit N0 to the slave unit N5 is changed. Is greater than or equal to a predetermined value. In this case, the first control unit 12 does not change the upper child device of the child device N4 in the route information, but changes the upper child device of the child device N5 to the child device N10. However, the first control unit 12 may change the higher-level child device of the child device N5 to the child device N10 by improving the route cost by changing the higher-level child device of the child device N5 to the child device N10.

  In addition, the first control unit 12 associates only the slaves whose number of hops to the master N0 is equal to or more than a predetermined number due to the change of the higher-order slave associated with the slave N6. The higher-level slave unit may be changed.

  For example, it is assumed that the predetermined number is 5, and the upper child device of the child device N6 has been changed to the child device N3. In this case, the number of hops of the child device N7 to the parent device N0 and the number of hops of the child device N8 to the parent device N0 are respectively changed from the higher-level child device associated with the child device N6 to the child device N3. As a result, the number of hops from the slave unit N10 to the master unit N0 increases from three to four, and from four to five. Therefore, the first control unit 12 associates only the child device N10 whose hop number to the parent device N0 is 5 or more due to the change of the higher-level child device associated with the child device N6 to the child device N10. The higher-level child device that has been set is changed, and the higher-level child device of the child device N7 and the upper child device of the child device N8 are not changed.

  Further, the first control unit 12 may further limit the slave unit that changes the higher-order slave unit to a slave unit including a slave unit that has the slave unit as the upper-order slave unit. For example, in the above example, when there is a child device having the child device N10 as the upper child device, the first controller 12 changes the upper child device associated with the child device N10. In the example of FIG. 1, there is no slave unit having the slave unit N10 as a higher-order slave unit. Therefore, even when the number of hops to the master unit becomes a predetermined number or more, the slave unit N10 does not change the upper-order slave unit.

  In addition, as described above, when the first control unit 12 detects that communication between the master unit N0 and the slave unit N1 is not possible, the upper slave unit of the slave unit N3 and the slave unit N6 Is changed, but among the slaves N3 and N6, the change of the upper slave is suspended until immediately before the slave is not used for communication. Good.

  For example, when the master unit N0 and the slave unit N4 communicate with each other, the first control unit 12 changes the upper slave unit of the slave unit N3, and changes the upper slave unit of the slave unit N6 when the master unit N0 changes the slave unit. It may be held until communication with the device N7 or the child device N8. Similarly, when the master unit N0 communicates with the slave unit N7, the first control unit 12 changes the upper slave unit of the slave unit N6, and the change of the upper slave unit of the slave unit N3 is performed, for example, by changing the master unit N0. May be held until communication with the slave unit N4 or the slave unit N5.

  As a result, only the higher-level child device required for communication is changed, so that the time required for the change can be reduced.

[Operation Example 8]
Incidentally, the above-described topology notification information is an example of route information. Specifically, for example, the slave unit is associated with a slave unit closer to the one-hop master unit N0 than the slave unit on the communication route. Information. FIG. 12A is a diagram illustrating an example of the topology notification information.

  The topology notification information illustrated in FIG. 12A is topology notification information transmitted from the child device N5 to the parent device N0. In the topology notification information shown in FIG. 12A, the child device N5 (address of the child device N5) is associated with the child device N4 closer to the one-hop parent device N0 than the child device N5.

  Here, when each of the slave units N1 to N10 transmits such topology notification information to the master unit N0, there is a concern that communication traffic increases.

  Therefore, when relaying the topology notification information, each of the slave units N1 to N10 may associate a higher-order slave unit of the slave unit with the topology notification information.

  For example, the slave unit N4 is configured such that the second communication unit 21 of the slave unit N4 transmits the topology notification information to the master unit N0 transmitted by the second communication unit 21 of the slave unit N5 farther from the master unit N0 by one hop than the slave unit N4. (Topology notification information shown in FIG. 12A) may be received. In this case, the slave N4 is an example of a second slave, and the slave N5 is an example of a third slave.

  In such a case, the second control unit 22 of the slave unit N4 transmits the topology notification information in which the slave unit N3 is further associated with the received topology notification information from the second communication unit 21 of the slave unit N4 to the slave unit N3. The second communication unit 21 is transmitted. FIG. 12B is a diagram illustrating an example of the topology notification information transmitted by the second communication unit 21 of the child device N4. Note that, in this case, the slave N3 is an example of a first slave.

  Similarly, a case is conceivable in which the second communication unit 21 of the child device N3 receives the topology notification information (the topology notification information shown in FIG. 12B) destined for the parent device N0 relayed by the second communication unit 21 of the child device N4. .

  In such a case, the second control unit 22 of the slave unit N3 transmits the topology notification information in which the slave unit N1 is further associated with the received topology notification information from the second communication unit 21 of the slave unit N3 to the slave unit N1. The second communication unit 21 is transmitted. FIG. 12C is a diagram illustrating an example of the topology notification information transmitted by the second communication unit 21 of the child device N4.

  According to the above configuration, if the base unit N0 receives the topology notification information from which the slave unit N5 is the transmission source, the master unit N0 knows the slave unit N3, the slave unit N4, and the higher-order slave unit of the slave unit N5. Can be. Then, since the child device N3 and the child device N4 do not need to separately transmit the topology notification information, the communication traffic is reduced.

[Summary]
As described above, the communication device (parent device N0) that operates as the parent device among the parent device and the plurality of child devices that constitute the communication route for performing the multi-hop communication includes the first storage unit 13, A first control unit 12. The first storage unit 13 is an example of a storage unit, and the first control unit 12 is an example of a control unit. The plurality of slaves include a first slave and a second slave farther from the first slave than the first slave on the communication route.

  In the first storage unit 13, each of the plurality of slaves is associated with only the higher-order slave which is closer to the one-hop master than the slave on the communication route among the slaves. Route information, which is route information indicating a communication route, is stored. When the first control unit 12 detects that it is impossible to communicate with the higher-level communication device closer to the one-hop master device than the first slave device on the communication route and the first slave device, the first controller 12 determines the route information. Of the higher-order slave units associated with the second slave unit. Note that the upper-level communication device may be a parent device, or may be one of the plurality of child devices.

  Thereby, the first control unit 12 can reconfigure the communication route (route information) when a link that does not allow communication between the slave units occurs on the communication route. Specifically, the first control unit 12 can reconfigure the communication route even when the first slave unit cannot communicate with a slave unit other than the higher-level communication device among the plurality of slave units.

  Further, when the first control unit 12 further detects that communication between the higher-level communication device and the first slave unit is not possible, the first control unit 12 sets the first slave unit in the route information as the higher-order slave unit. The higher-level child device associated with another child device other than the second child device may be changed.

  As a result, the first control unit 12 changes the upper handset of another handset other than the second handset in addition to the second handset having the first handset as the upper handset. be able to. That is, the first control unit 12 can change the two higher-level slave units included in the route information by one detection.

  Further, the first control unit 12 is configured such that communication between the upper communication device and the first slave device is impossible, and the slave devices other than the upper communication device with which the first slave device can communicate include a plurality of slave devices. When it is detected that the second slave unit is not included in the route information, the higher-order slave unit associated with the second slave unit in the route information may be changed.

  Accordingly, the first control unit 12 can reconfigure the communication route (route information) even when the first slave unit cannot communicate with the slave unit other than the upper communication device among the plurality of slave units. it can.

  Also, as in the operation example 3, when the first control unit 12 detects that communication between the higher-level communication device and the first slave unit is not possible, the first control unit 12 transmits the route information to the second slave unit in the route information. The associated upper child device may be changed, and the upper child device associated with the first child device in the route information may be changed to the second child device.

  This can increase the possibility that the communication route can be reconfigured.

  Further, the first control unit 12 is configured to detect a case where communication between the higher-level communication device and the first slave unit is not possible, and to determine whether the second slave unit can communicate with the first slave unit. When it is detected that a slave other than the slave is not included in the plurality of slaves, the higher-order slave associated with the second slave in the route information is changed, and the first slave in the route information is changed. May be changed to the second slave unit.

  This can increase the possibility that a communication route can be reconfigured when a plurality of slaves do not include a slave other than the second slave with which the first slave can communicate.

  When the first control unit 12 determines that it is impossible to change the upper slave unit associated with the second slave unit, the first control unit 12 is farther from the master unit than the second slave unit on the communication route. The determination is made as to whether the lower child device is the target lower child device in which the upper child device associated with the lower child device can be changed, in order from the lower child device closer to the second child device. You may go until you find a child device. The first control unit 12 may change the upper child device associated with the lower child device determined to be the target lower child device in the route information.

  Thereby, even when it is determined that the change of the upper child device associated with the second child device is impossible, it is possible to increase the possibility that the communication route can be reconfigured.

  In addition, the first control unit 12 changes the upper child device associated with the second child device in the route information from the second child device when the candidate child device included in the plurality of child devices is changed. The number of hops to the parent device is specified, and in the change of the higher-level child device associated with the second child device in the route information, the candidate child device whose specified hop number is equal to or less than the hop number before the change is determined. Alternatively, the change target slave unit may be prioritized over the candidate slave unit in which the specified hop number is larger than the hop number before the change.

  Thereby, the first control unit 12 can suppress an increase in the number of hops when changing the upper child device of the second child device.

  Further, the plurality of slave units are fourth slave units farther from the master unit than the second slave unit on the communication route, and communicate with the master unit via the second slave unit. Fourth slave units may be included, and the first control unit 12 may further change the higher-order slave unit associated with the fourth slave unit in the route information.

  Thereby, the first control unit 12 can improve the communication route by further changing the upper child device of the fourth child device.

  In addition, the first storage unit 13 stores communication quality information indicating communication quality between two slave units included in the plurality of slave units, and the first control unit 12 further stores a fourth one of the route information. The upper child device associated with the child device may be changed based on the communication quality information.

  Thereby, the first control unit 12 can improve the communication quality in the changed communication route by further changing the higher-order slave unit of the fourth slave unit.

  In addition, the first control unit 12 is configured to change the upper child device associated with the second child device in the route information, so that the route cost to the parent device becomes a predetermined value or more due to the change of the fourth child device. The higher-level child device associated with the device may be changed.

  Thereby, the first control unit 12 can suppress an increase in route cost (a decrease in communication quality) when the upper child device of the second child device is changed.

  Further, the first control unit 12 is configured to control the fourth slave unit in which the number of hops to the master unit becomes equal to or more than a predetermined number due to the change of the higher-order slave unit associated with the second slave unit in the route information. May be changed.

  Thereby, the first control unit 12 can suppress an increase in the number of hops when changing the upper child device of the second child device.

  Further, when there is a child device having the fourth child device as the upper child device among the plurality of child devices, the first control unit 12 is associated with the second child device in the route information. The upper child device associated with the fourth child device in which the number of hops to the parent device becomes a predetermined number or more due to the change of the higher child device may be changed.

  As a result, the first control unit 12 selectively changes the upper child device of the fourth child device having the lower number of hops to the parent device and having the lower child device. Thus, an increase in the number of hops can be suppressed.

  Further, when the master unit and the target slave unit communicate with each other, the first control unit 12 changes the higher-order slave unit associated with the second slave unit used for the communication in the route information. Of the route information, the upper handset of the second handset not used in the communication may suspend the change until it is used in the communication.

  Further, the multi-hop communication system 100 includes a master unit and a plurality of slave units that constitute a communication route for performing multi-hop communication, and the plurality of slave units include a first slave unit and a communication route on the communication route. A second slave unit farther from the one-hop master unit than the first slave unit is included.

  The master unit includes a first storage unit 13 and a first control unit 12. In the first storage unit 13, each of the plurality of slaves is associated with only the higher-order slave which is closer to the one-hop master than the slave on the communication route among the slaves. Route information, which is route information indicating a communication route, is stored. When the first control unit 12 detects that it is impossible to communicate with the higher-level communication device closer to the one-hop master device than the first slave device on the communication route and the first slave device, the first controller 12 determines the route information. Of the higher-order slave units associated with the second slave unit.

  Thereby, the first control unit 12 can reconfigure the communication route when a link that cannot communicate with the child devices occurs on the communication route. Specifically, the first control unit 12 can reconfigure the communication route even when the first slave unit cannot communicate with a slave unit other than the higher-level communication device among the plurality of slave units.

  Further, each of the plurality of slaves further transmits, to the master, topology notification information in which the slave is associated with a slave closer to the one-hop master than the slave on the communication route. Two communication units 21 may be provided. The topology notification information is an example of route notification information, and the second communication unit 21 is an example of a communication unit.

  Thereby, each of the plurality of slave units can notify the master unit of a higher-order slave unit of the slave unit. The parent device can create the route information based on the topology notification information, and store the created route information in the first storage unit 13.

  In the second handset, the second communication unit 21 of the third handset further transmits the second communication unit 21 of the second handset farther from the one-hop master than the second handset. When the route notification information is received, the topology notification information in which the first child device is further associated with the received route notification information is transmitted from the second communication unit 21 of the second child device to the second child device of the first child device. A second control unit 22 that causes the communication unit 21 to transmit may be provided. The second control unit is an example of a slave unit control unit.

  This allows the third slave unit to add the upper slave unit of the second slave unit to the topology notification information of the transmission source, so that the second slave unit needs to separately transmit the topology notification information. Absent. Therefore, communication traffic is reduced.

  Further, in the communication method executed by the multi-hop communication system 100, the multi-hop communication system 100 includes a master unit and a plurality of slave units that constitute a communication route for performing the multi-hop communication. The plurality of slaves include a first slave and a second slave farther from the first hop master than the first slave on the communication route.

  The master unit is route information in which each of the plurality of slave units is associated with only a higher-order slave unit that is closer to the one-hop master unit than the slave unit on the communication route among the plurality of slave units. And a first storage unit 13 in which route information indicating a communication route is stored. The communication method includes, when detecting that communication between the higher-level communication device closer to the one-hop master device than the first slave device and the first slave device on the communication route is not possible, the first slave device in the route information. The upper slave unit associated with the second slave unit is changed.

  Thereby, the first control unit 12 can reconfigure the communication route when a link that cannot communicate with the child devices occurs on the communication route. Specifically, the first control unit 12 can reconfigure the communication route even when the first slave unit cannot communicate with a slave unit other than the higher-level communication device among the plurality of slave units.

  Further, in the communication method executed by the multi-hop communication system 100, the multi-hop communication system 100 includes a master unit and a plurality of slave units that constitute a communication route for performing the multi-hop communication.

  In the communication method, each of the plurality of slaves transmits, to the master, topology notification information in which the slave is associated with a slave closer to the one-hop master than the slave on the communication route.

  Thereby, each of the plurality of slave units can notify the master unit of a higher-order slave unit of the slave unit. The parent device can create the route information based on the topology notification information, and store the created route information in the first storage unit 13.

(Other embodiments)
The multi-hop communication system according to the embodiment has been described above, but the present invention is not limited to the above-described embodiment.

  The specific mode of the communication device operating as the master device or the communication device operating as the slave device described in the above embodiment is not particularly limited. For example, an air conditioner, a smart meter, a lighting device, or the like may be used as the communication device. Further, the master unit and the slave unit do not need to be the same type of communication terminal. When the slave unit is a smart meter, the master unit is a concentrator (server) or the like that manages data acquired from the slave unit. Is also good.

  In the above-described 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.

  Further, in the above-described embodiment, a process executed by a specific processing unit may be executed by another processing unit. Further, the order of the plurality of processes may be changed, or the plurality of processes may be executed in parallel.

  Note that the general or specific aspects of the present invention may be realized by a recording medium such as a system, a method, an integrated circuit, a computer program or a computer-readable CD-ROM, and the system, the method, the integrated circuit, and the computer. It may be realized by an arbitrary combination of a program or a recording medium. For example, the present invention may be realized as a multi-hop communication system, or a communication method executed by a master unit or a slave unit included in the multi-hop communication system, or for causing a computer to execute such a communication method. It may be realized as a program.

  As described above, the multi-hop communication system according to one or more aspects and the communication device and the communication method used in the multi-hop communication system have been described based on the embodiments. However, the present invention is not limited to this embodiment. It is not something to be done. Unless departing from the spirit of the present invention, various modifications conceivable to those skilled in the art may be applied to this embodiment, and a form constructed by combining components in different embodiments may be in the range of one or more aspects. May be included within.

11 first communication unit 12 first control unit (control unit)
13 First storage unit (storage unit)
21 Second communication unit (communication unit)
22 Second control unit (child unit control unit)
23 second storage unit 100 multi-hop communication system N0 master unit N1 to N10 slave unit

Claims (19)

Constructing a communication route for performing multi-hop communication, a communication device that operates as the master device, among the master device and the plurality of slave devices,
The plurality of slaves include a first slave and a second slave farther from the master by one hop than the first slave on the communication route,
The communication device,
Each of the plurality of slaves is route information associated only with a higher-order slave which is one hop closer to the master than the slave on the communication route among the plurality of slaves. A storage unit in which route information indicating the communication route is stored;
When it is detected that communication between the higher-level communication device closer to the master unit and the first slave unit is one hop closer to the master unit than the first slave unit on the communication route, the route information includes A communication unit comprising: a control unit configured to change an upper child device associated with the second child device from the first child device to another child device. The control unit, further, when it is detected that communication between the upper communication device and the first slave unit is impossible, the route information and the first slave unit as the upper slave unit in the route information The communication device according to claim 1, wherein an upper child device associated with another child device other than the second child device is changed from the first child device to another child device. The control unit is configured to disable communication between the higher-level communication device and the first slave, and to determine that the slaves other than the higher-level communication device with which the first slave can communicate include the plurality of slaves. When detecting that it is not included in the handset, the higher-order handset associated with the second handset in the route information is changed from the first handset to another handset. 3. The communication device according to 2. The control unit, when detecting that communication between the upper communication device and the first slave device is not possible, the higher slave device associated with the second slave device in the route information. Changing from the first slave unit to another slave unit, and changing a higher-order slave unit associated with the first slave unit in the route information to the second slave unit. The communication device according to any one of claims 1 to 3. The control unit is a case where it is detected that communication between the upper communication device and the first slave unit is impossible, and the second slave unit with which the first slave unit can communicate. If it is detected that a child device other than the child device is not included in the plurality of child devices, the higher-level child device associated with the second child device in the route information is separated from the first child device. The communication device according to claim 4, wherein the communication device is changed to the second slave device, and a higher-order slave device associated with the first slave device in the route information is changed to the second slave device. The control unit includes:
If it is determined that it is not possible to change the upper child device associated with the second child device from the first child device to another child device, the second child device on the communication route A determination is made as to whether or not a lower child device that is farther from the parent device than the parent device is a target lower child device in which an upper child device associated with the lower child device can be changed, which is closer to the second child device. Performs in order from the lower child unit until the target lower child unit is found,
The communication device according to any one of claims 1 to 5, wherein, of the route information, an upper child device associated with the lower child device determined to be the target lower child device is changed. The control unit includes:
The second child in the case where the higher-level slave associated with the second slave in the route information is changed from the first slave to a candidate slave included in the plurality of slaves. The number of hops from the machine to the parent machine,
In the route information, in the change from the first handset of the upper handset associated with the second handset, the candidate handset whose specified hop count is less than or equal to the hop count before the change. The communication device according to any one of claims 1 to 6, wherein the communication device according to any one of claims 1 to 6, wherein the specified handset has a higher priority than the candidate handset in which the specified hop count is larger than the hop count before the change. The plurality of slaves are, on the communication route, a fourth slave that is farther from the master than the second slave, and communicate with the master via the second slave. Includes a fourth handset to communicate,
The communication device according to any one of claims 1 to 7, wherein the control unit further changes an upper child device associated with the fourth child device in the route information. The storage unit stores communication quality information indicating communication quality between two slave units included in the plurality of slave units,
The communication device according to claim 8, wherein the control unit further changes a higher-order slave unit associated with the fourth slave unit in the route information based on the communication quality information. The control unit is configured to reduce the route cost to the parent device by changing the higher-level child device associated with the second child device from the first child device to another child device in the route information. The communication device according to claim 9, wherein a higher-order slave unit associated with the fourth slave unit that is equal to or greater than a predetermined value is changed. The control unit is configured such that, in the route information, the number of hops to the parent device is changed by changing the higher-level child device associated with the second child device from the first child device to another child device. The communication device according to claim 9, wherein a higher-order slave unit associated with the fourth slave unit that is equal to or more than a predetermined number is changed. The control unit, when there is a child device having the fourth child device as an upper child device among the plurality of child devices, is associated with the second child device in the route information. Changing the upper child device associated with the fourth child device in which the number of hops to the parent device is equal to or more than a predetermined number due to the change of the higher child device from the first child device to another child device The communication device according to claim 11. The control unit includes:
When the master and the target slave communicate with each other, a higher-level slave associated with the second slave used for the communication is separated from the first slave in the route information. Change to the child unit ,
The communication device according to any one of claims 1 to 12, wherein, of the route information, a higher-level slave unit of the second slave unit that is not used in the communication holds a change until it is used for communication. Constructing a communication route for performing multi-hop communication, comprising a master unit and a plurality of slave units,
The plurality of slaves include a first slave and a second slave farther from the master by one hop than the first slave on the communication route,
The master unit is
Each of the plurality of slaves is route information associated only with a higher-order slave which is one hop closer to the master than the slave on the communication route among the plurality of slaves. A storage unit in which route information indicating the communication route is stored;
When it is detected that communication between the higher-level communication device closer to the master unit and the first slave unit is one hop closer to the master unit than the first slave unit on the communication route, the route information includes A control unit for changing a higher-level slave associated with the second slave from the first slave to another slave . Each of the plurality of slave units further transmits, to the master unit, route notification information that associates the slave unit with a slave unit that is one hop closer to the master unit than the slave unit on the communication route. The multi-hop communication system according to claim 14, further comprising: a communication unit that performs communication. The second slave unit may further include a route notification transmitted by the communication unit of a third slave unit, wherein the communication unit of the second slave unit is one hop farther from the master unit than the second slave unit. When the information is received, the route notification information further associating the first slave unit with the received route notification information, the communication unit of the first slave unit from the communication unit of the second slave unit The multi-hop communication system according to claim 15, further comprising: a slave unit control unit configured to transmit the information to the communication device.   A communication device that operates as a slave provided in the multi-hop communication system according to any one of claims 14 to 16. A communication method performed by a multi-hop communication system,
The multi-hop communication system constitutes a communication route for performing multi-hop communication, includes a master unit and a plurality of slave units,
The plurality of slaves include a first slave and a second slave farther from the master by one hop than the first slave on the communication route,
The master unit is such that each of the plurality of slave units is associated with only a higher-order slave unit that is one hop closer to the master unit than the slave unit on the communication route, among the slave units. A storage unit storing route information indicating the communication route,
The communication method, when it is detected that the communication between the first communication device and the upper communication device closer to the master 1 hop than the first communication device on the communication route is impossible, A communication method for changing a higher-level child device associated with the second child device from the route information from the first child device to another child device . A program for causing a computer to execute the communication method according to claim 18 .

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