JP5472064B2 - Data transfer device, data transfer method, and data transfer program - Google Patents

Description

  The present invention relates to a data transfer device, a data transfer method, and a data transfer program.

  Conventionally, DTN (Delay / Disruption Tolerant Networking) is known as a network control method for realizing highly reliable data transfer in a communication environment in which a physical link between nodes does not always exist. In DTN, data to be transferred is temporarily stored in the relay node, and when there is no connection to the next hop, the data is stored in the relay node, waits for transfer, and is transferred when connected to the next hop. Data is transferred by this method (Store and forward method). DTN is defined in RFC4838. In DTN, there is a possibility that the delay of data transfer may be large, but even in an unstable and low-reliability communication environment, the end-to-end data delivery probability can be increased.

  When transmitting and receiving data between DTN nodes, the following two data transmission methods (routing methods) are mainly known. The first is a method called epidemic routing, where each node moves randomly and distributes data copies to all the nodes it encounters (other nodes that fall within range). It is a method. The second is a method called Message Ferry, in which a mobile node that circulates between fixed nodes exchanges data with the fixed node.

  In DTN, a method of preferentially transferring content to a node in which a part of the content to be transferred is stored as a cache fragment has been proposed. Furthermore, a method has been proposed in which a DTN creates a mobile station location management table from a connection history between a mobile station and a fixed station and distributes the mobile station location management table to the fixed station.

JP 2008-205890 A JP 2009-55511 A

  However, in epidemic routing, a copy of the data is sent to all the nodes that are encountered, so the amount of data stored in each node increases and the traffic also increases when viewed in the entire network. Therefore, each node requires a large storage area, and a large amount of data needs to be exchanged when it encounters another node. As a result, the amount of data that can be exchanged within a limited time is limited.

  In the message ferry, an increase in traffic is suppressed, but a problem arises that a fixed node located outside the cyclic route cannot communicate forever. In addition, it is difficult to solve the above problems with the data transfer systems described in Patent Documents 1 and 2.

  The disclosed technology has been made in view of the above, and provides a data transfer device, a data transfer method, and a data transfer program that enable highly reliable data transfer while suppressing the amount of data to be transferred. Objective.

  The data transfer device disclosed in the present application detects other nodes within the communication range, and the detected other nodes, a communication unit that performs data communication, and the communication unit detects and enables direct communication. A route recording unit for recording route data including information indicating the node of the node and information indicating a route to the node indirectly communicable via the other node, and content data to be transferred Content data recording unit that accumulates in association with information indicating the destination node, and when the communication unit detects another node, the route data of the other node is received and added to the route data of the route recording unit And when the communication unit detects the other node, the route update unit refers to the route data of the route recording unit after the route data of the other node is added by the route update unit. , And a transmission control section that controls whether to transmit the content data to the other nodes.

  According to one aspect of the data transfer device disclosed in the present application, it is possible to perform highly reliable data transfer while suppressing the amount of data to be transferred.

FIG. 1 is an example of a network system including a data transfer apparatus according to the first embodiment. FIG. 2 is a functional block diagram illustrating an example of the configuration of the data transfer apparatus. FIG. 3 is a diagram illustrating examples of protocol layers in the Internet and DTN. FIG. 4 is a flowchart illustrating an operation example of the data transfer apparatus according to the first embodiment. FIG. 5A is a diagram illustrating an example of route data and routes before encounter. FIG. 5B is a diagram illustrating an example of route data and a route of the node A after the node A encounters the node B. FIG. 6 is a diagram illustrating a specific example of a network system using DTN. FIG. 7 is a diagram for explaining an operation example of the DTN network to which the epidemic routing method is applied. FIG. 8 is a diagram for explaining an operation example of the DTN network to which the message ferry method is applied. FIG. 9 is a functional block diagram of a configuration example of the data transfer apparatus according to the second embodiment. FIG. 10 is a diagram illustrating a specific example of route data according to the present embodiment. FIG. 11A is an example of a route table when there are three paths from node A to node D. FIG. FIG. 11B is a diagram illustrating three paths from node A to node D. FIG. 12 is a diagram illustrating a specific example of the route attribute data according to the present embodiment. FIG. 13 is a diagram illustrating an example of a periodic update process of the route attribute table. FIG. 14 is a diagram illustrating an example of data of a system specified value in the data transfer apparatus 1a. FIG. 15A is a diagram illustrating another example of the route attribute table. FIG. 15B is a diagram showing still another example of the route attribute table. FIG. 16 is a flowchart illustrating an operation example of the data transfer apparatus according to the second embodiment. FIG. 17 is a diagram illustrating an example of a route before and after node A encounters node B. FIG. FIG. 18 is an example of a route table showing a route state before encountering the node A and the node B. FIG. 19 is a diagram illustrating an example after nodes A and B have encountered, received the route tables of the other party, and added to the respective route tables. FIG. 20A is a diagram illustrating an example of a route table and a route after nodes C and D have encountered at time t1. FIG. 20B is a diagram illustrating an example of a route table and a route after nodes B and C have encountered at time t2. FIG. 20C is a diagram illustrating an example of a route table and a route after node B and node E have encountered at time t3. FIG. 20D is a diagram illustrating an example of a route table and a route after nodes A and F have encountered at time t4. FIG. 20E is a diagram illustrating an example of a route table and a route after nodes A and G have encountered at time t5. FIG. 20F is a diagram illustrating an example of a route table and a route after nodes A and B have encountered at time t6. FIG. 21 is a diagram illustrating an example of updating the node attribute table when the node A encounters the node B. FIG. 22A is an example of each route table and route before node A and node B meet. FIG. 22B is an example of a route table and a route after encountering node A and node B. FIG. FIG. 22C is an example of the route attribute table in node A after encountering node A and node B. FIG. FIG. 23 is a diagram illustrating an example of the route table and the route of the node A before encountering the node A and a node C other than the node B on the route having the highest encounter accuracy. FIG. 24 is a diagram illustrating an example of a route table and a route of the node A after the node A and the node C are encountered. FIG. 25 is a schematic diagram illustrating the data transfer process performed by the data transfer apparatus according to the third embodiment. FIG. 26 is a functional block diagram of a configuration example of the data transfer apparatus according to the third embodiment. FIG. 27 is a diagram illustrating an example of the route of the node A and the route table before the node A and the node C meet. FIG. 28 is a diagram illustrating an example of the route of the node A and the route table after the encounter between the node A and the node C. FIG. 29 is a flowchart illustrating an operation example of the data transfer apparatus according to the third embodiment. FIG. 30 is a flowchart illustrating a processing procedure of update path data generation processing. FIG. 31 is a flowchart illustrating a processing procedure of data transmission determination processing. In FIG. 32, node A and node B are encountered, and a plurality of paths B-H-Z, B-I-Z, B-J-Z, B-K-Z, and B-L- It is a figure which shows the mode in which Z exists, and the route table of the node A. FIG. 33 is a diagram for explaining the data transfer process performed by the data transfer apparatus according to the fourth embodiment. FIG. 34 is a functional block diagram of a configuration example of the data transfer apparatus according to the fourth embodiment. FIG. 35 is a diagram illustrating a data example of a system specified value in the data transfer apparatus. FIG. 36 is a diagram illustrating an example of the route table of the node A before the encounter between the node A and the node B. FIG. 37 is a diagram illustrating an example of the route table of the node A after the encounter. FIG. 38 is a diagram illustrating an example of a data structure of transmission data. FIG. 39 is a diagram illustrating an example of transmission data in which four paths are added to content data. FIG. 40 is a diagram for explaining processing by another node that has received transmission data. FIG. 41 is a flowchart illustrating an operation example of the data transfer apparatus according to the fourth embodiment. FIG. 42 is a flowchart illustrating a processing procedure of update route data generation processing. FIG. 43 is a flowchart illustrating a processing procedure of data transmission determination processing.

  Hereinafter, embodiments of a data transfer device, a data transmission method, and a data transfer program disclosed in the present application will be described in detail with reference to the drawings. The following examples do not limit the disclosed technology.

  FIG. 1 is an example of a DTN network system including a data transfer apparatus according to the first embodiment. DTN is a communication method in which data is transferred by the Store And Forward method in a communication environment where a physical link does not always exist. Each of the plurality of nodes A to D in the network system shown in FIG. 1 has a function of performing data communication with other nodes in the communication range and a function of storing data. Each of the plurality of nodes A to D moves in the direction of the dashed arrow, and forwards the stored data to other nodes when the other nodes are within the communication range. Each node A to D retains data when there is no other node in the communication range. Each node of the DTN can be either a data source, a data forwarder, a data destination, or a combination thereof. In this embodiment, data to be transferred from the transmission source to the destination is referred to as content data. The DTN node may include a node that does not move.

[Configuration example of data transfer device]
FIG. 2 is a functional block diagram illustrating an example of the configuration of the data transfer apparatus serving as the node A. The other nodes B to D can have the same configuration. A data transfer apparatus 1 shown in FIG. 2 includes a communication unit 2, a control unit 3, a memory 6, and a storage 8. The control unit 3 is, for example, a CPU. The functions of the path update unit 4 and the transmission control unit 5 are realized by the CPU executing a predetermined program. A program for causing a computer to execute the functions of the communication unit 2, the path update unit 4, and the transmission control unit 5 or a recording medium on which such a program is recorded is also included in this embodiment.

  The memory 6 is a storage device that can be read and written by a CPU, such as a ROM and a RAM. The memory 6 includes a route recording unit 7 for recording route data. The storage 8 is, for example, a recording device that can record data continuously. The storage 8 includes a content data recording unit 9 for storing content data. The content data recording unit 9 stores the content data to be transferred in association with information indicating the destination node.

  The communication unit 2 detects other nodes within the communication range of the data transfer apparatus 1 and performs data communication with the detected other nodes. For example, the communication unit 2 can start communication when another node approaches the data transfer device 1 and communication with a wireless LAN or bluetooth (registered trademark) is possible. The DTN communication can be realized by a protocol layer called a bundle layer (Bundle layer) overlaid on the transport layer, for example. FIG. 3 is a diagram illustrating examples of protocol layers in the Internet and DTN. A node (DTN host / DTN router / DTN gateway) having a bundle layer shown in the lower part of FIG. 3 is called a DTN node, and in particular, a DTN router and a DTN gateway are sometimes called a Forwarder. Note that the protocol below the transport layer below the Bundle layer is not limited to TCP / IP and is arbitrary. In DTN, communication between nodes may be ad hoc communication.

  The path recording unit 7 includes information indicating other nodes (hereinafter referred to as “direct nodes”) detected by the communication unit 2 and capable of direct communication, and nodes that can communicate indirectly via the direct node. Route data including information indicating a route to (hereinafter referred to as “indirect node”) is recorded. For example, in the example shown in FIG. 1, another node B that can communicate directly with the node A can directly communicate with another node C, and the node C can communicate with another node D directly. In such a case, the content data from the node A can be transmitted to the node D. In general, since a moving node often moves in the vicinity thereof geographically, the node C can communicate directly with the node B in the near future, and the node B can communicate with the node A directly. . Thereby, the content data from the node D can be transmitted to the node A. In this case, node A and node D can communicate indirectly. In this way, the nodes A, B, C, and D can be assumed to be in a communicable state directly or indirectly. Note that a node can be represented by a node identifier such as EID, for example. The EID is a DTN node unique number defined in RFC4843.

  When the communication unit 2 detects another node, the route update unit 4 receives the route data of the other node and adds it to the route data of the route recording unit 7. In addition, when the communication unit 2 detects another node, the transmission control unit 5 refers to the route data of the route recording unit 7 after the route data of the other node is added to the other node. It is determined whether to transmit the content data. The route recording unit 7 may, for example, send the destination node to the node that can communicate indirectly via the other node when the other node is the destination node of the content data or the route indicated by the route data. Is included, the content data is transmitted to the other node. In this case, the content data is transmitted to the other node via the communication unit 2.

[Operation example of data transfer device]
FIG. 4 is a flowchart illustrating an operation example of the data transfer apparatus 1 when the communication unit 2 detects another node. In the example shown in FIG. 4, when the communication unit 2 detects another node, the route update unit 4 receives the route data of the other node and adds it to the route data of the route recording unit 7 (step S1). . At this time, the route update unit 4 may transmit the route data of the route recording unit 7 to the other node. This allows the encountered nodes and route data to be exchanged with each other.

  Here, with reference to FIG. 5A and FIG. 5B, a specific example in the case of adding route data received from another node that has entered (encountered) the communication range to the route data of the own node will be described. FIG. 5A is a diagram showing an example of the contents of route data and a route before node A can communicate with node B, that is, before encounter. In the example shown in FIG. 5A, the node A is already communicable with the node F and the node G. Neither node F nor node G can communicate with other nodes. Here, the fact that communication is possible (encountered) may mean that communication is not possible at the present time.

  FIG. 5B is a diagram illustrating an example of the content of the route data of the node A after the node A encounters the node B and adds the route data received from the node B. In the example shown in FIG. 5B, Node B has already encountered Node C and Node E, and Node C has encountered Node D before encountering Node B. Therefore, Node B is added to the route data as a direct node that can communicate directly, and Nodes E, C, and D are added to the route data as indirect nodes that can communicate indirectly via Node B. Is done. Information indicating routes to the nodes E, C, and D is also added. For example, since the route to the node D passes from the node A to the node B and the node C, the information indicating the route is “BC”.

  In this way, the transmission control unit 5 refers to the route data to which the route data of the other node that has been encountered is added, and determines whether or not to transfer the content data to the other node that has been encountered. Judgment is made (step S2). For example, when the destination node of the content data is the node D, in the example shown in FIG. 5B, the route data includes a route that reaches the node D via the node B that has been encountered. Determines to transfer the content data to the node B. Therefore, the communication unit 2 transmits content data having the destination node as the node D to the node B (step S3). The processes in steps S2 and S3 are repeated until all the content data recorded in the content data recording unit 9 is completed (step S4).

  As described above, the nodes A to D are the data transfer apparatus 1 configured as shown in FIG. 2, so that when a certain node encounters another node, it receives the route data and does not directly encounter the node. It is possible to manage route information including (nodes that can communicate indirectly). As a result, even when a node that is not directly encountered is the destination node of the content data, it is possible to recognize the destination node path and transfer the data. Further, the data transfer device 1 configured as described above does not transfer data to all the nodes encountered as in the case of epidemic routing, and transfers the data when the encountered node is a node connected to the route to the destination node. Therefore, it is possible to recognize the route to the destination and transfer the content data to an appropriate node while suppressing an increase in traffic volume in the network. As a result, highly reliable data communication is possible.

[Application example of DTN]
FIG. 6 is a diagram illustrating a specific example of a network system using DTN. In the example shown in FIG. 6, sensors S for measuring temperature, humidity, and sunshine hours are arranged in an entire area, and the information is collected at a government office and the entire area is managed. This is an example of utilizing DTN technology in the business of managing In the example shown in FIG. 6, each sensor S is provided with a DTN communication device. In addition, DTN communication devices are also installed in a plurality of people or vehicles and in a government office. A device having a DTN communication device can be called a DTN node. In this example, the sensor S is a source that is a data transmission source, a data transfer device carried by a person or vehicle passing on the road is a Forwarder (F), and a node of a government office is a destination node (destination). Source, Forwarder, and Destination are all DTN nodes.

  The sensor S transmits content data to the forwarder when a person or vehicle with the forwarder enters the communication range. The content data is, for example, measurement data obtained by measurement of the sensor S, and is transmitted to the forwarder together with information indicating that the destination node is a government office node. At this time, the sensor S can receive the route data from the Forwarder, and can transmit the content data to the Forwarder when the route data includes the information of the route to the government office node.

  When the forwarder who received the content data passes the other forwarder on the road, it receives the route data of the other forwarder and adds it to his route data, and the route data includes the route information to the government office node. If so, the content data is transmitted. Thereby, the measurement information of each sensor S is finally collected at the government office via the Forwarder. Here, each Forwarder can select a partner to which the content data is transferred so that the route is highly likely to be transferred to the government office node. As a result, it is possible to transfer data through a highly reliable route while suppressing an increase in traffic volume in the local network.

[Example of epidemic routing method]
FIG. 7 is a diagram for explaining an operation example of the DTN network to which the epidemic routing method is applied. In the example shown in FIG. 7, the content data is delivered from the source node (src) to the destination node (dst) in phases 1-5. However, the content data transferred to Node 5 in Phase 4 and the content data transferred to Node 1 in Phase 5 remain stored in the node without reaching the destination node. Thus, in the epidemic routing method, there is a possibility that a large amount of useless data that does not reach the destination node may occur.

For example, consider the case where 100 sensors S transmit 1 KB of data to the government office in the above example. If there are 100 forwarders, and each forwarder encounters only one sensor S and a government office node, the necessary storage area and data transfer amount are as follows. This is the case where the traffic volume is minimized.
The storage area required for one Forwarder is only 1 KB.
The amount of data transfer that occurs in one Forwarder is only reception = 1 KB and transmission = 1 KB.

If the forwarder frequently encounters a sensor or another forwarder, the worst case is that one sensor information is sent to all forwarders (100) + remaining sensors (99). In this case, the necessary storage area and data transfer amount are as follows.
The storage area required for one Forwarder is information on all sensors (100KB). The amount of data transfer that occurs in one Forwarder is: reception = 100KB, transmission = 100KB * 199
In other words, the epidemic routing method requires a large storage area in the forwarder, and the amount of data to be exchanged when encountering other forwarders is enormous, so data that can be exchanged within a limited time The problem is that the amount is limited.

[Example of message ferry method]
FIG. 8 is a diagram for explaining an operation example of the DTN network to which the message ferry method is applied. In the example shown in FIG. 8, the content data is delivered from the source node (src) to the destination node (dst) as the mobile node (Node 2) circulates in phases 1 to 3. However, if the mobile node does not pass within the communication range of the source node in phase 2, the content data is not delivered to the destination node. That is, a fixed node located at a place off the traveling route cannot communicate forever.

  According to the data transfer apparatus according to the present embodiment, content data can be transferred by selecting a node to which a route to a destination node may be connected. Therefore, it is highly reliable while suppressing an increase in traffic volume. Data transfer is possible in the route. Also, data can be sent to the final destination node even if there is no Forwarder that circulates a fixed route, as in message ferry routing. Therefore, both the above-mentioned problem of the epidemic routing method and the problem of the message ferry method can be solved.

  FIG. 9 is a functional block diagram of a configuration example of the data transfer apparatus 1a according to the second embodiment. In FIG. 9, the functional blocks corresponding to the functional blocks in FIG.

[Configuration example for routing considering communication reliability]
The data transfer apparatus 1a shown in FIG. 9 further includes a path attribute recording unit 11 that records data indicating the detection frequency of other nodes (hereinafter referred to as “direct nodes”) that have been detected by the communication unit 2 and are capable of direct communication. Prepare. The route update unit 4 calculates a value indicating the degree of certainty of communication with the direct node based on the detection frequency of the direct node. Further, the route update unit 4 uses the detection frequency and the route data received from the direct node to be able to indirectly communicate with each route indicated by the route data (hereinafter referred to as “indirect node”). A value indicating the degree of certainty of communication with is calculated. The route update unit 4 adds a value indicating the degree of certainty of communication with the calculated direct node and a value indicating the degree of certainty of communication with the indirect node to the route data, 7 to the route data.

  When the route data of the route recording unit 7 includes a plurality of routes to the destination node of the content data, the transmission control unit 5 further uses a value indicating the degree of certainty of communication to the destination node in each route, It is determined whether to transmit to the other node. Thereby, content data can be transferred to another node in consideration of the degree of certainty of communication. Therefore, data transfer can be performed with a more reliable route.

  The detection frequency of the direct node represents the frequency at which other nodes can directly communicate with the data transfer apparatus 1a, that is, the frequency at which other nodes have entered the communication range. Therefore, the detection frequency of the direct node can be said to be the frequency of encountering another node. The direct node detection frequency can be calculated using, for example, the number of times other nodes have entered the communication range in a certain past period. By using such a detection frequency with the direct node, a value indicating the certainty that the direct communication with the direct node can be performed in the future can be calculated. Therefore, it can be said that the value indicating the degree of certainty of communication with the direct node is an estimated value obtained based on the past communication history with the direct node.

  Since information indicating the certainty of direct communication with the direct node is included in the route data, when the route data is received from the node that encountered it, it communicates with each node on the route connected by direct communication with other nodes. It is possible to calculate the certainty of

[Configuration example for routing considering transfer destination capacity]
In the present embodiment, the route attribute recording unit 11 further records data indicating a free capacity capable of storing content data in other nodes that can communicate. The transmission control unit 5 can further determine whether or not to transmit to the other node by further using the free capacity that can store the content data in the other node. Thereby, routing in consideration of the capacity of the transfer destination becomes possible.

  For example, if the free capacity of another node encountered by the data transfer device 1a is smaller than the content data to be transmitted, the transmission control unit 5 can determine that the content data is not transmitted. For example, when the route data includes a plurality of routes to the destination node of the content data, the transmission control unit 5 can give priority to the route with the larger free capacity of the next hop node.

[Configuration example for switching transmission control functions]
The data transfer apparatus 1a illustrated in FIG. 9 further includes an interface unit 12 that receives a transmission control function switching instruction from the user. The transmission control unit 5 switches the operation mode based on the switching instruction received by the interface unit 12. In the operation mode, a mode in which the communication unit 2 detects that the communication unit 2 always transmits the content data to other communicable nodes, and whether the content data is transmitted to other nodes with reference to the route data. A mode that operates to control is included. When the transmission control unit 5 operates to always transmit content data to another node, traffic in the network increases, but the certainty that the content data reaches the destination node increases. For this reason, even if the increase in traffic is allowed, when there is a request to reliably deliver content data, the data transfer apparatus 1a can be switched to a data transfer method that easily satisfies the request.

  In the example shown in FIG. 9, the data transfer device 1 a includes an instruction input unit 13 from the user and an information output unit 14 for the user. The interface unit 12 controls data I / O via these input means 13 and output means 14. The input means 13 is, for example, a button. The output means 14 is, for example, a status lamp or a speaker. For example, the user can switch the operation mode by pressing a button. Further, by turning on or blinking the status lamp, the user can visually recognize the current operation mode. The input means 13 can be an emergency button for changing the process to the epidemic routing method in the event of an emergency such as a disaster. In this case, when the user presses this button in the event of an emergency such as a disaster, the data transfer device 1a enters the “emergency mode”. When in "Emergency mode", the routing method is Epidemic routing. Since the epidemic routing is performed, for example, it is possible to increase the probability of collecting information that an isolated node exists in a disaster or the like.

[Specific examples of route data and route attribute data]
FIG. 10 is a diagram illustrating a specific example of route data according to the present embodiment. FIG. 10 shows a route table of the node A as an example of route data. In the route table, the partner node, the route to the partner node, the date and time, and the encounter probability value are recorded. The “partner” is an EID that identifies a destination node, that is, a direct node and an indirect node, with which the node A can communicate directly or indirectly. “Route” is route information. The EIDs of the route nodes are recorded from the own node A to the partner node in the closest order. In the example shown in FIG. 10, the path being “−” means that direct communication is possible. Further, since the route information to the node D is “BC”, it means that the DTN communication can be performed from the node A to the node D via the node B and the node C.

  “Date and time” is the date and time when the partner node first encountered the node (the last node in the node recorded in the route). The “encounter accuracy” is an example of a value indicating the degree of certainty of communication, and is a probability that it can be encountered in the future. In this example, the encounter accuracy takes a value of 0 to 1. This value can be calculated by, for example, “encounter accuracy calculation process” described later.

  As in the example shown in FIG. 10, the route data is communicated directly with another node at the time when the direct communication with the other node is possible, or the node that becomes indirectly communicable first on the route. Information indicating the time when it became possible can be included. Thereby, the continuation of the data regarding the route can be controlled based on the elapsed time from the time when the partner node can communicate with another node first. For example, after a predetermined time elapses from the time when the partner node can communicate first, information indicating the route to the node can be deleted from the route table. For example, the data transfer device 1a can search for a route in which a predetermined time has elapsed since the first communication became possible in the route table in a predetermined cycle, and can delete the corresponding route. In this embodiment, the predetermined time is recorded in the data transfer device 1a as a route table storage period, which will be described later as an example.

  Further, as in the example shown in FIG. 10, the route data includes a value indicating the degree of certainty of communication with the partner node, so that the data in the route table is optimized according to the certainty of communication. Can do. For example, the data transfer apparatus 1a may check the route table at a predetermined cycle, and delete data related to a node whose encounter accuracy is lower than a predetermined value (in this embodiment, an encounter accuracy minimum limit value described later as an example). it can. When managing the encounter accuracy, it is possible to efficiently prevent the DTN route table from becoming bloated by deleting a route lower than the “minimum encounter accuracy value” defined by the system. It is possible to prevent the storage unit from being pressed.

  In the route table, a plurality of routes can be registered for the same counterpart node. FIG. 11A is an example of a route table when there are three paths from node A to node D. FIG. FIG. 11B is a diagram illustrating three paths from node A to node D.

  FIG. 12 is a diagram illustrating a specific example of the route attribute data according to the present embodiment. FIG. 12 shows a route attribute table of node A as an example of route attribute data. In the route table, the partner node, history flag, and remaining capacity are recorded. These pieces of information are recorded for each partner node that node A has encountered so far and has become capable of direct communication, that is, for each direct node. In this example, the nodes C, D, and E that have no experience to directly communicate with the node A are not registered in the route attribute table of the node A.

  The “history flag” is an example of data indicating the detection frequency of the partner node. Each flag from “−4 days” to “today” in the “history flag” column indicates whether or not each time zone has been encountered. For example, in each time zone, the flag has a value of 1 if it has been encountered and 0 if it has not been encountered. The history flag is an example of data indicating a history of past encounters. The “remaining HD amount” is an example of data indicating a free capacity capable of storing content data in another node that has been encountered. This is the remaining capacity of the content data storage area in the partner node when the node A was last encountered. For example, when the route update unit 4 encounters a partner node, it can receive the value of the remaining HD amount from the partner node and record it in the route attribute table.

  Further, the data transfer device 1a can update the route attribute table at a predetermined cycle. For example, information indicating the history of past encounters can be periodically updated as time passes. In the example shown in FIG. 12, since the history flag indicating the presence / absence of encounters every day is recorded, it is preferable to update the history flag at a cycle of one day. FIG. 13 is a diagram illustrating an example of a periodic update process of the route attribute table. In the example shown in FIG. 13, the flags for each time zone are shifted one by one to the past time zone. The flag of the oldest time zone (-4 days) is deleted, and the flag of the newest time zone (today) is cleared to 0.

  FIG. 14 is a diagram illustrating an example of data of a system specified value in the data transfer apparatus 1a. The system specified value table shown in FIG. 14 records a route attribute table monitoring period, a route table storage period, and a minimum encounter accuracy value. The system specified value table can be recorded in the storage 8, for example. Further, it is preferable that the values in the system specified value table are set in common for nodes included in one area in the DTN network.

  The “route attribute table monitoring cycle” is a value that defines the update cycle of the route attribute table. The example shown in FIG. 12 is preferably set to “1 day”. In other words, it is preferable that the length of time used as a reference for the flag indicating the history of encounters and the route attribute table monitoring period be the same. Also, by shortening the route attribute table monitoring period, the node encounter frequency (detection frequency) can be managed in a shorter unit. In addition, when the route attribute table monitoring period is set longer, the encounter frequency can be managed in a longer unit. FIG. 15A shows an example of the route attribute table when “route attribute table monitoring period” = 1 hour. FIG. 15A shows an example of the contents of the route attribute table at the time of 10 o'clock. FIG. 15B shows an example of the route attribute table when “route attribute table monitoring period” = 1 week.

  “Route table retention period” is a value indicating the retention period of the record recorded in the route table. For example, as described above, the storage period can be determined on the basis of the time (the date and time shown in FIG. 10) when the partner node first becomes directly communicable.

[Operation example]
FIG. 16 is a flowchart illustrating an operation example of the data transfer apparatus 1a according to the second embodiment. FIG. 16 is an operation example of the data transfer device 1a when the communication unit 2 detects another node. In FIG. 16, the same number is attached | subjected to the process process corresponding to the process process of FIG. In the example shown in FIG. 16, the route update unit 4 updates route data (step S1). Here, a specific example of the route data update process will be described.

[Specific example of route data update processing (when node A and node B encounter)]
FIG. 17 is a diagram illustrating an example of a route connected from the node A and the node B before the node A encounters the node B and becomes communicable, and after the node A encounters the node B. FIG. 18 is an example of a route table showing a route state before encountering the node A and the node B. As shown in FIG. 18, the EID route, the date and time, and the encounter accuracy are recorded for each of the node K, the node L, and the node M in the route table of the node A before the encounter. In the route table of the node B before encounter, EID, route, date / time, and encounter accuracy are recorded for each of the node X, node Y, and node Z.

FIG. 19 is a diagram illustrating an example after nodes A and B have encountered, received the route tables of the other party, and added to the respective route tables. For example, the route table shown in FIG. 18 is updated like the route table shown in FIG. 19 by the following processes (1) to (5).
(1) Node A adds the encountered node B to the route table of node A. Since node A encounters node B and communicates directly, the path is set to "-" (none). As the date and time, the time t1 when the node A and the node B can communicate with each other is recorded. The encounter accuracy will be described later.
(2) The node B adds the encountered node A to the route table of the node B. Since Node B encounters Node B and communicates directly, the path is set to “-” (none). As the date and time, the time t1 when the node A and the node B can communicate with each other is recorded.
(3) The record of the route table of the node B before the encounter (the records of the nodes X, Y, and Z) is added to the route table of the node A. Further, since B is relayed for the route of the added record, “B” is inserted at the head. As the date and time, the times tx, ty1, and tz2 at which the counterpart nodes X, Y, and Z can first communicate directly with other nodes B, Y1, and Z2 on the route are recorded.
(4) The record of the route table of the node A before encounter (the records of the nodes K, L, M) is added to the route table of the node B. Further, since A is relayed for the route of the added record, “A” is inserted at the head. As the date and time, the times tk, tl1, and tm2 at which the counterpart nodes K, L, and M can first communicate directly with other nodes A, L1, and M2 on the route are recorded.
(5) The node A and the node B refer to the date and time data for all the records in the respective route tables, and the elapsed time from the time indicated by the date and time data exceeds the “route table storage period”. Search for records The record that exceeds is deleted from the route table.

[Example of route table generation when each node repeats encounters]
Each node updates and generates a route table by exchanging the contents of the route table each time it encounters another node. The example shown in FIGS. 20A to 20F is a process in which nodes C and D meet each other at a time = t1, and thereafter, nodes B and C meet a time = t2. This shows how each route table is built. Time flows in the order of t1, t2, t3, t4, t5, and t6. In the figure showing the route on the right side of the table, the solid line connects the nodes encountered at that time, and the dotted line connects the nodes that have been exchanged in the past.

  FIG. 20A is a diagram illustrating an example of a route table and a route after nodes C and D have encountered at time t1. The record of node D is added to the route table of node C, and the record of node C is added to the route table of node D.

  FIG. 20B is a diagram illustrating an example of a route table and a route after nodes B and C have encountered at time t2. In addition to the record of node C, the record of node D that can communicate indirectly through node C is also added to the route table of node B. Hereinafter, similarly, the record of the node of the encountered partner and the record of the node that can communicate indirectly through the encountered partner are added to the route table.

  20C shows a case where node B and node E are encountered at time t3, FIG. 20D shows a case where node A and node F are encountered at time t4, and FIG. 20E shows a case where node A and node G are encountered at time t5. FIG. 20F is a diagram showing a route table and a route when node A and node B meet at time t6. The route table generated as shown in FIGS. 20A to 20F recognizes that, for example, node A can communicate with node D via node B and node C by referring to its own route table. it can.

[Example of route attribute data update processing]
Referring to FIG. 16 again, when the route data is updated, the route update unit 4 also updates the route attribute data (step S11 in FIG. 16). FIG. 21 is a diagram illustrating an example of updating the node attribute table when the node A encounters the node B. For example, the node attribute table is updated by the following processes (1) to (3).
(1) If the encounter partner node is not registered in the route table, it is newly registered.
(2) The value in the current column of the “history flag” of the encounter partner node is updated to 1. For example, when the route attribute table monitoring cycle is in units of 1 day, 1 is set in the “Today” column as shown in FIG.
(3) Receive information on the remaining HD amount from the encounter partner node and register it in the route attribute table.

[Example of encounter accuracy calculation]
When the route attribute data is updated as described above, the route update unit 4 calculates a value indicating the degree of certainty of communication with the partner node included in the route data for each partner node, The addition to the route data is also updated (step S12 in FIG. 16). Here, a calculation example of encounter probability, which is an example of a value indicating the degree of certainty of communication, will be described. The encounter accuracy of the encounter partner node that has encountered and communicated directly can be calculated based on the data in the route attribute table. For example, when the route attribute table monitoring period is one day, the encounter accuracy of the encounter partner node can be calculated by the following equation (A).

The encounter accuracy of the partner node that can communicate indirectly via the encounter node can be calculated using the encounter accuracy of the encounter node and the encounter accuracy recorded in the route table of the encounter partner. it can. The encounter accuracy of the node registered in the route table of the encounter partner that directly communicated can be calculated by, for example, the following equation (B).
Encounter accuracy = Encounter accuracy of encounter partner x Encounter accuracy at encounter partner (B)

  Note that the route update unit 4 may delete records of nodes whose calculated encounter accuracy is smaller than the “minimum encounter accuracy value” in the system specified value table (see FIG. 14) from the route table.

  Here, with reference to FIG. 22A to FIG. 22C, an example of calculating the encounter accuracy when the node A encounters the node B will be described. FIG. 22A is an example of the route table and the route before the encounter between the node A and the node B, FIG. 22B is an example of the route table and the route after the encounter, and FIG. 22C is the route attribute in the node A after the encounter. It is an example of a table.

First, when the route update unit 4 calculates the encounter accuracy of the directly encountered node B based on the route attribute table shown in FIG. 22C according to the calculation formula (A), the following formula (1) is obtained.
(1): B encounter accuracy = (1/1 + 1/3 + 1/4 + 1/5) / (1/1 + 1/2 + 1/3 + 1/4 + 1/5) = 0 .781
Next, for the nodes E, C, and D registered in the route table of the node B, the above calculation is performed based on the encounter accuracy values 0.5, 0.4, and 0.2 of the route table on the node B. When calculated according to the equation (B), the following equations (2) to (4) are obtained.
(2): E encounter accuracy = 0.781 (B encounter accuracy at A) * 0.5 (E encounter accuracy at B) = 0.391 (3): C encounter accuracy = 0.781 (B Encounter accuracy at A) * 0.4 (C encounter accuracy at B) = 0.312 (4): D encounter accuracy = 0.781 (B encounter accuracy at A) * 0.2 (D encounter accuracy) Accuracy at B) = 0.156
The values of the calculation results of the above formulas (1) to (4) correspond to the location data indicated by (1) to (4) in FIG. 22B. Also. In the above formulas (1) to (4), “encounter accuracy at B” means the encounter accuracy at node B.

[Example of transmission control]
As described above, when the encounter accuracy is calculated (step S12), the transmission control unit 5 determines whether or not to transmit the content data (steps S21 and S2). The transmission control unit 5 first determines an operation mode determined based on a switching instruction from the user (step S21). In the present embodiment, as an example, the operation mode includes “emergency mode” and “normal mode”. The user inputs an operation mode switching instruction via the input unit 13, and the interface unit 12 receives the user switching instruction.

  In the case of the emergency mode, it is determined that the content data is transmitted to the currently encountered node. In this case, the transmission control unit 5 transmits all the content data to the currently encountered node (step S22). That is, in the emergency mode, the transmission control unit 5 transmits the content data unconditionally to a node that has encountered it without determining whether or not the content data needs to be transmitted with reference to the route data.

In the normal mode, the transmission control unit 5 refers to the route table and determines whether or not content data transmission is necessary (step S2). For example, the transmission control unit 5 can determine whether or not content data transmission is necessary by comparing information on a route to another node indicated in the route table with a destination node of the content data. As an example, the transmission control unit 5 can determine by the following processes (1) to (4).
(1) A route (also referred to as a route or a route) toward the EID of the destination node of the content data is extracted from the route table.
(2) If there is no route connected to the destination node, it is determined not to transmit the content data.
(3) When there is only one route to the destination node, the following determination processes (a) and (b) are executed.
(A) When the route matches the currently encountered node (when the currently encountered node is included in the route), it is determined to transmit.
(B) Otherwise, it is determined not to transmit.
(4) When two or more routes exist, the following processes (c) to (e) are executed.
(C) Under the condition that “the size of transmission data is smaller than the remaining HD amount in the route attribute table”, a route with the highest encounter accuracy is extracted.
(D) If there is no route as a result of (c) above, it is determined not to transmit.
(E) If a route is extracted as a result of (c) above, if the route matches the currently encountered node, it is determined to transmit. Otherwise, it is determined not to transmit.

  As a result of the above determination, if it is determined to transmit, the content data is transmitted to the encountering node (step S3). Moreover, the transmission control part 5 performs the said judgment (step S2) and transmission (step S3) about all the content data of the content data recording part 9 (step S4). Thereby, appropriate routing according to the destination of each content data becomes possible.

  The operation example of the data transfer device 1a has been described above, but the operation of the data transfer device 1a is not limited to the above example. For example, when there are a plurality of routes to the destination node of the content data in the route data, it is possible to determine whether transmission to other nodes encountered is necessary so that the content data is transferred through the plurality of routes. Further, when the free capacity of the other node encountered is smaller than the content data to be transmitted, the transmission can be prevented.

  The data transfer device 1a of the first and second embodiments can be preferably used as a node in the DTN. For example, DTN collects sensor information such as communication in the event of a disaster, communication in an area that cannot be connected to the Internet, and sensors that are not connected to a normal network, in addition to communication in interplanetary communication, for example. It can also be used as a means to do this. The present invention is not limited to the first and second embodiments.

  In the second embodiment, when there are a plurality of routes to the destination node of the content data, when a node on the route having the highest encounter accuracy matches the node currently encountered, the route on the route having the highest encounter accuracy is obtained. Send content data to the node. However, if communication with a node other than the node on the route with the highest encounter accuracy is possible at this time, it is possible to achieve more reliable data transfer by transmitting content data to the node. is there.

  First, with reference to FIG. 23 and FIG. 24, a problem caused by not transmitting content data to a node other than the node on the route with the highest encounter accuracy when communication becomes possible at this time will be described. FIG. 23 is a diagram illustrating an example of the route table and the route of the node A before encountering the node A and a node C other than the node B on the route having the highest encounter accuracy. FIG. 24 is a diagram illustrating an example of a route table and a route of the node A after the node A and the node C are encountered.

  In the example shown in FIG. 23, there are two routes from the node A to the destination node Z: a route via the node B and a route via the node C. The encounter accuracy of the route passing through the node B is 0.49 (= 0.7 × 0.7), and the encounter accuracy of the route passing through the node C is 0.45 (= 0.5 × 0.9). Higher than. Under such circumstances, when node A encounters node B on the route having the highest encounter probability of 0.49 with reference to the route table of node A, node A transmits content data to node B. try to. In other words, the node A does not transmit content data to the node C even when it can communicate with the node C other than the node B on the route having the highest encounter probability of 0.49 at the present time.

  When node A encounters node C and becomes communicable at this time, the encounter accuracy of node C with respect to node Z is 0.9, as shown in FIG. It becomes higher than 0.49. For this reason, if node A transmits content data to node C that is currently communicable, it is more reliable than transmitting content data to node B on the route with the highest encounter accuracy in the route table. Data transfer will be realized. However, since the route with the highest encounter accuracy in the route table is still the route via the node B, the node A cannot transmit content data to the node C even when the node A can communicate with the node C at the present time. . As a result, the reliability of data transfer is reduced.

  As described above, if the value of encounter accuracy in the route table is used as it is to determine whether or not data transmission is necessary, the reliability of data transfer is lowered. Therefore, in this embodiment, the route table is updated when communication with a node other than the node on the route with the highest encounter accuracy in the route table is possible at the present time, and data transmission is performed using the updated route table. Judgment is necessary.

  A specific example will be described with reference to FIG. FIG. 25 is a diagram for explaining the data transfer process performed by the data transfer apparatus 1b according to the third embodiment. FIG. 25 shows an example of the route table and route of node A after encountering node A and node C. In FIG. 25, it is assumed that the node A corresponds to the data transfer apparatus 1b. Further, it is assumed that there are two routes from the node A to the destination node Z: a route via the node B and a route via the node C. In the route table before node A encounters node C, the encounter accuracy of the route passing through node B is 0.49, which is higher than the encounter accuracy 0.45 of the route passing through node C. To do.

  As shown in FIG. 25, it is assumed that node A encounters node C and can communicate at this time. The node A that can communicate with the node C has an encounter probability of 1 that matches the node C when the node C matches the node in the route table and the node on the route to the destination node Z. The encounter accuracy in the route table is corrected so that In the example of FIG. 25, when node A corrects the encounter accuracy in the route table, the encounter accuracy of partner node C becomes 1, and the partner node Z that can communicate indirectly through the route via node C The encounter accuracy is 0.9.

  Then, the node A determines whether or not data transmission is necessary using the updated route table. In the example of FIG. 25, the node A refers to the updated route table and extracts a route via the node C having the highest encounter probability of 0.9 from the route toward the destination node Z. The content data can be transmitted to the node C encountered in

  As described above, the data transfer device 1b according to the third embodiment updates the route table when communication with a node other than the node on the route having the highest encounter probability in the route table is possible at the current time, and the updated route The necessity of data transmission is determined using a table. For this reason, the data transfer apparatus 1b can determine whether or not data transmission is necessary using the correct encounter accuracy after correction, and can realize highly reliable data transfer.

[Configuration Example of Data Transfer Device According to Embodiment 3]
Next, a configuration example of the data transfer apparatus according to the third embodiment will be described. FIG. 26 is a functional block diagram of a configuration example of the data transfer apparatus 1b according to the third embodiment. In FIG. 26, functional blocks corresponding to the functional block diagram of FIG.

  A data transfer apparatus 1b illustrated in FIG. 26 includes a path update unit 4b and a transmission control unit 5b, respectively, instead of the path update unit 4 and the transmission control unit 5 illustrated in FIG. The route update unit 4b and the transmission control unit 5b basically have the same processing functions as the route update unit 4 and the transmission control unit 5 shown in FIG. Below, it demonstrates centering on a processing function different from the path | route update part 4 and the transmission control part 5 which were shown in FIG. 9 among the processing functions of the path | route update part 4b and the transmission control part 5b.

The route update unit 4b is a direct node that matches another node when another node detected by the communication unit 2 matches a direct node of the route data in the route recording unit 7 and a node on the route to the indirect node. The route data is updated by correcting the encounter accuracy using the encounter accuracy. The encounter accuracy after correction can be calculated by the following equation (C), for example.
(Encounter accuracy after correction) = (Encounter accuracy of direct node and indirect node) / (Encounter accuracy of direct node that matches the encounter partner) (C)

  Here, with reference to FIG. 27 and FIG. 28, a specific example of processing by the path update unit 4b before and after the node A encounters the node C will be described. FIG. 27 is a diagram illustrating an example of the route and route table of the node A before the encounter between the node A and the node C, and FIG. 28 is a diagram illustrating an example of the route and route table of the node A after the encounter. .

  As shown in FIG. 27, before the node A and the node C meet, there are two paths from the node A to the destination node Z: a path via the node B and a path via the node C. . The encounter accuracy of the route passing through the node B is 0.49, which is higher than the encounter accuracy of the route passing through the node C of 0.45.

As shown in FIG. 28, when the node A encounters the node C and becomes communicable at the present time, the path updating unit 4b determines that the node C that is currently encountered is the other node C and the other party in the route table of the node A. It is determined whether or not the first node C on the route to the node matches. The route update unit 4b determines the encounter accuracy and the node C of the node C when the node C currently encountered matches the partner node C in the route table of the node A and the leading node C on the route to the partner node. The encounter accuracy of the node Z that has become indirectly communicable via is corrected. The corrected encounter accuracy is calculated according to the calculation formula (C), and is as shown in the following formulas (5) and (6).
(5) Encounter accuracy after correction of node C = 0.50 (encounter accuracy of direct node C) /0.50 (encounter accuracy of direct node C) = 1
(6) Encounter accuracy after correction of node Z that can communicate indirectly via node C = 0.45 (encounter accuracy of indirect node Z) /0.50 (encounter accuracy of direct node C)
The values of the calculation results of the above formulas (5) and (6) correspond to the entry data indicated by (5) and (6) in FIG.

  In this way, the route update unit 4b, when the other node encountered matches the direct node of the route data in the route recording unit 7 and the node on the route to the indirect node, the direct node that matches the other node. The route data is updated by correcting the encounter accuracy using the encounter accuracy. Then, when the route update unit 4b executes the update process for all the partner nodes in the route data, the route update unit 4b records the updated route data in the route recording unit 7 separately from the route data before the update. Hereinafter, the updated route data recorded in the route recording unit 7 by the route update unit 4b may be referred to as “update route data”.

  In addition, after updating the route data in the route recording unit 7, the route update unit 4 b deletes the updated route data from the route recording unit 7 when the communication unit 2 no longer detects another node in the communication state. Thereby, it is possible to prevent the update path data from squeezing the memory during a period when the data transfer apparatus 1b does not encounter another node.

  Returning to FIG. 26, the transmission control unit 5 b uses the encounter accuracy in the updated route data of the route recording unit 7 to determine whether or not to transmit the content data to another node detected by the communication unit 2. The content data is transmitted to the determined other node. Specifically, when the updated route data of the route recording unit 7 includes a plurality of routes to the destination node of the content data, the transmission control unit 5b extracts and extracts the route having the highest encounter probability from each route. The content data is transmitted to another node using the route.

[Operation Example of Data Transfer Apparatus According to Third Embodiment]
Next, an operation example of the data transfer apparatus according to the third embodiment will be described. FIG. 29 is a flowchart illustrating an operation example of the data transfer apparatus 1b according to the third embodiment. FIG. 29 is a processing procedure of data transfer processing by the data transfer device 1b when the communication unit 2 detects another node. In FIG. 29, the same number is attached | subjected to the process process corresponding to the process process of FIG.

  In the example shown in FIG. 29, when the communication unit 2 detects another node, the route update unit 4b receives the route data of the other node and adds it to the route data of the route recording unit 7 (step S1). . When the route data of another node is added to the route data, the route update unit 4b updates the route attribute data (step S11).

  Then, when the route attribute data is updated, the route update unit 4b calculates the encounter accuracy indicating the degree of certainty of communication with the partner node included in the route data for each partner node, and the route of the route recording unit 7 It adds to data (step S12).

  When the encounter accuracy is added to the route data, the route update unit 4b executes an updated route data generation process (step S13). FIG. 30 is a flowchart illustrating a processing procedure of update path data generation processing.

  As shown in FIG. 30, the route update unit 4b duplicates the route data (route table) of the route recording unit 7 and expands it in a predetermined working memory area (step S131). Subsequently, the route update unit 4b determines whether or not the node currently encountered matches the partner node in the route table and the leading node on the route to the partner node (step S132).

  When the currently encountered node does not match the partner node in the route table and the leading node on the route to the partner node (No at step S132), the path update unit 4b advances the process to step S134. On the other hand, when the currently encountered node matches the partner node and the leading node on the route to the partner node (Yes in step S132), the route update unit 4b uses the encounter probability of the matching direct node. The encounter accuracy is corrected (step S133).

  Subsequently, the path update unit 4b repeatedly executes the determination process in step S132 and the correction process in step S133 for all the partner nodes in the path data (No in step S134). Then, when the route update unit 4b executes the correction process in step S133 for all the partner nodes in the route data (Yes in step S134), the updated route data is recorded in the route recording unit 7 as updated route data (step S134). S135).

  Returning to the description of FIG. 29, when the update path data generation process is executed (step S13), the transmission control unit 5b determines whether or not to transmit the content data. The transmission control unit 5b first determines an operation mode determined based on a switching instruction from the user (step S21). In the present embodiment, as an example, the operation mode includes “emergency mode” and “normal mode”. The user inputs an operation mode switching instruction via the input unit 13, and the interface unit 12 receives the user switching instruction.

  When the operation mode is the emergency mode (No at Step S21), the transmission control unit 5b determines to transmit the content data to the currently encountered node. In this case, the transmission control unit 5b transmits all the content data to the currently encountered node (step S22). That is, when the operation mode is the emergency mode, the content data is unconditionally transmitted to the node that has encountered it without determining whether or not the content data needs to be transmitted with reference to the route data.

  When the operation mode is the normal mode (Yes at Step S21), the transmission control unit 5b executes a data transmission determination process for determining whether transmission of content data is necessary with reference to the updated route data of the route recording unit 7. (Step S23). FIG. 31 is a flowchart illustrating a processing procedure of data transmission determination processing.

  As shown in FIG. 31, the transmission control unit 5b extracts a route (hereinafter also referred to as “route” or “route”) toward the destination node of the content data from the update route data (step S231). If there is no route to the destination node (No at Step S232), the transmission control unit 5b determines not to transmit the content data (Step S233).

  When there is only one route toward the destination node (Yes at Step S232, No at Step S234), the transmission control unit 5b matches the node that is currently encountered with the node on the route toward the destination node. Is determined (step S235). If the node on the route to the destination node matches the node currently encountered (Yes at Step S235), the transmission control unit 5b determines to transmit the content data (Step S239). On the other hand, when the node on the route toward the destination node does not match the node currently encountered (No at Step S235), the transmission control unit 5b determines not to transmit the content data (Step S233).

  On the other hand, when there are two or more routes toward the destination node (Yes at Step S232, Yes at Step S234), the transmission control unit 5b performs the following processing. In other words, the transmission control unit 5b extracts a route having the highest encounter probability from the respective routes toward the destination node under the condition that “the size of the transmission data is smaller than the remaining HD amount in the route attribute table” (Step S1). S236).

  If there is no route with the highest encounter probability under the condition that the size of the transmission data is smaller than the remaining HD amount in the route attribute table (No at Step S237), the transmission control unit 5b transmits the content data. It is determined not to do so (step S233).

  On the other hand, when a route having the highest encounter probability is extracted under the condition that the size of the transmission data is smaller than the remaining HD amount in the route attribute table (Yes in step S237), the transmission control unit 5b Perform the process. That is, the transmission control unit 5b determines whether or not the node on the extracted route matches the currently encountered node (step S238). When the node on the extracted route matches the node currently encountered (Yes at Step S238), the transmission control unit 5b determines to transmit the content data (Step S239). On the other hand, if the node on the extracted route does not match the currently encountered node (No at Step S238), the transmission control unit 5b determines not to transmit the content data (Step S233).

  Returning to the description of FIG. 29, when the data transmission determination process is executed (step S23), the transmission control unit 5b determines that the data transmission determination process is to be transmitted (Yes in step S24), and the content data is currently Transmit to the encountering node (step S25). Then, the transmission control unit 5b deletes the content data after transmission from the content data recording unit 9 (step S26). On the other hand, if it is determined in the data transmission determination process that transmission is not to be performed (No at step S24), the transmission control unit 5b advances the process to step S27 without transmitting content data.

  Subsequently, the transmission control unit 5b repeatedly executes the processes in steps S23 to S26 for all the content data in the content data recording unit 9 (No in step S27). Then, when the transmission control unit 5b executes the processes of steps S23 to S26 for all the content data in the content data recording unit 9 (Yes in step S27), the data transfer process is terminated.

  As described above, the data transfer device 1b according to the third embodiment uses the encounter probability of the direct node when the currently encountered node matches the node on the route to the direct node and the indirect node of the route data. The route data is updated by correcting the encounter accuracy. Then, the data transfer device 1b determines whether or not to transmit the content data to the currently encountered node using the corrected encounter probability in the updated route data that is the updated route data. For this reason, the data transfer apparatus 1b can determine whether or not data transmission is necessary using the correct encounter accuracy after correction, and can realize highly reliable data transfer.

  Further, the data transfer device 1b according to the third embodiment, when the currently encountered node is the destination node of the content data, or when the currently encountered node is included in the indirect node of the route data, Send content data to the currently encountered node. Thereby, the data transfer device 1b can enable appropriate data transfer according to the destination of the content data.

  In the third embodiment, when the currently encountered node matches the direct node of the route data and the node on the route to the indirect node, the route accuracy is corrected by using the encounter accuracy of the direct node and correcting the encounter accuracy. Update. However, there is a problem that the encounter accuracy is not accurate when there are a plurality of routes ahead of the node currently encountered in the updated route data.

  With reference to FIG. 32, a problem in the case where a plurality of paths exist ahead of the currently encountered node will be described. In FIG. 32, node A and node B are encountered, and a plurality of paths B-H-Z, B-I-Z, B-J-Z, B-K-Z, and B-L- It is a figure which shows the mode in which Z exists, and the route table of the node A.

  In the example shown in FIG. 32, there are a total of six routes including one route via node R and five routes via node B as routes from node A to destination node Z. Further, the encounter accuracy of one route passing through the node R is 0.11, which is higher than the encounter accuracy 0.1 of five routes passing through the node B. Under such circumstances, the node A refers to the route table of the node A, and when the node R encounters the node R on the route having the highest encounter probability of 0.11, transmits the content data to the node R. try to. In other words, the node A does not transmit content data to the node B even when it can communicate with the node B other than the node R on the route having the highest encounter accuracy of 0.11 at the present time.

However, there are five paths B-HZ, B-I-Z, B-J-Z, B-K-Z, and B-L-Z through the node B beyond the currently encountered node B. It is also assumed that node B encounters any of nodes H, I, J, K, and L on these multiple paths. This means that the node A can indirectly communicate with the destination node Z through any one of the five routes passing through the node B. In general, the encounter accuracy of the node Z that can communicate indirectly through any one of the five routes passing through the node B can be calculated by the following equation (D).
Z encounter accuracy = 1- (1- [path B-H-Z encounter accuracy]) × (1- [path B-I-Z encounter accuracy) × (1- [path B-J-Z Encounter Accuracy]) × (1- [Encounter Accuracy of Path B-K-Z]) × (1- [Encounter Accuracy of Path B-L-Z]) (D)
= 1- (1-0.1) x (1-0.1) x (1-0.1) x (1-0.1) x (1-0.1)
= 0.4

  A node Z that can be indirectly communicated through any one of the five routes that pass through the node B has an encounter accuracy of 0.4, and a node that can communicate indirectly through the route that passes through the node R. The encounter accuracy of Z is higher than 0.11. Therefore, if the node A transmits the content data to the node B that is currently encountered, the data transfer is more reliable than the content data transmitted to the node R on the route having the highest encounter accuracy in the route table. Will be realized. However, since the path with the highest encounter accuracy in the route table is the path via the node R, the node A cannot transmit the content data to the node B even when the node A is currently encountering the node B. As a result, the reliability of data transfer is reduced.

  In this way, when there are multiple routes ahead of the node that is currently encountered, using the encounter accuracy value in the route table as it is to determine whether or not data transmission is necessary reduces the reliability of data transfer. End up. Therefore, in this embodiment, the route table is updated when there are a plurality of routes ahead of the node currently encountered, and the necessity of data transmission is determined using the updated route table.

  A specific example will be described with reference to FIG. FIG. 33 is a diagram for explaining the data transfer process performed by the data transfer apparatus 1c according to the fourth embodiment. In FIG. 33, it is assumed that the node A corresponds to the data transfer device 1c. Further, it is assumed that there are one route passing through the node R and five routes passing through the node B as the route from the node A to the destination node Z. In the route table before node A encounters node B, the encounter accuracy of the route passing through node R is 0.525, and the encounter accuracy of five routes passing through node B is 0.276, 0.276. , 0.238, 0.186, and 0.216.

  As shown in FIG. 33, it is assumed that node A encounters node B and can communicate at this time. The node A that has become communicable with the node B performs the following processing when the node B matches a node on the route to the same counterpart node Z in the route table. That is, the node A indirectly uses any one of the plurality of routes using the communication accuracy of the partner node Z that can communicate indirectly with the plurality of routes including the node that matches the node B. The encounter accuracy of the counterpart node that can communicate is calculated. In the example of FIG. 33, communication is possible indirectly through five paths B-HZ, B-I-Z, B-J-Z, B-K-Z, and B-L-Z including the node B. Using the communication accuracy of the node Z, the encounter accuracy of the node Z that can communicate indirectly through any one of the five routes is calculated. That is, the encounter accuracy of the node Z that can communicate indirectly through any one of the five routes is calculated as 0.687, and the route table of the node A is updated.

  Then, the node A determines whether or not data transmission is necessary using the updated route table. In the example of FIG. 33, the node A refers to the updated route table and extracts a route that passes through the node B having the highest encounter probability of 0.687 from the route toward the destination node Z. The content data can be transmitted to the Node B encountered in

  As described above, the data transfer apparatus 1c according to the fourth embodiment updates the route table when there are a plurality of routes ahead of the currently encountered node, and transmits data using the updated route table. Judgment is necessary. For this reason, the data transfer device 1c can determine whether or not data transmission is necessary by using the correct encounter accuracy after correction even when there are a plurality of routes ahead of the node being encountered. Reliability can be further improved.

[Configuration Example of Data Transfer Device According to Embodiment 4]
Next, a configuration example of the data transfer apparatus according to the fourth embodiment will be described. FIG. 34 is a functional block diagram of a configuration example of the data transfer apparatus 1c according to the fourth embodiment. In FIG. 34, functional blocks corresponding to those in the functional block diagram of FIG.

  A data transfer apparatus 1c illustrated in FIG. 34 includes a path update unit 4c and a transmission control unit 5c, respectively, instead of the path update unit 4b and the transmission control unit 5b illustrated in FIG. The route update unit 4c and the transmission control unit 5c basically have the same processing functions as the route update unit 4b and the transmission control unit 5b shown in FIG. Hereinafter, the processing functions different from the path update unit 4b and the transmission control unit 5b illustrated in FIG. 26 among the processing functions of the path update unit 4c and the transmission control unit 5c will be mainly described.

The route update unit 4c performs the following process when another node detected by the communication unit 2 matches a node on a plurality of routes reaching the same indirect node in the route data of the route recording unit 7. The route update unit 4c indirectly uses any one of the plurality of routes using the encounter accuracy of the indirect node that can indirectly communicate with the plurality of routes including the node that matches the other node. The route data is updated by calculating the encounter accuracy of the indirect node that can communicate. The encounter accuracy of an indirect node that can communicate indirectly through any one of a plurality of routes can be calculated by, for example, the following equation (E).
(Encounter accuracy) = 1− (1− [encounter accuracy of path 1]) × (1− [encounter accuracy of path 2]) × (1− [encounter accuracy of path 3]) × (1− [path 4 Encounter accuracy]) x ... (E)
In Expression (E), “the encounter accuracy of route 1” means the encounter accuracy of an indirect node that can indirectly communicate with route 1 including a node that matches another node.

  In addition, the route update unit 4c uses the encounter accuracy exceeding the predetermined value among the encounter accuracy of the indirect nodes that can be indirectly communicated with the plurality of routes including the node that matches the other node, among the plurality of routes. The encounter accuracy of an indirect node that can communicate indirectly through any one route is calculated. Thereby, the encounter accuracy of the above formula (E) can be calculated with higher accuracy using the encounter accuracy exceeding a predetermined value.

  In this embodiment, the predetermined value is a parallel path determination threshold value calculated using a “parallel path determination threshold value calculated” defined by the system as an example. The parallel path determination threshold calculation value is recorded in the data transfer device 1c as a system specified value. FIG. 35 is a diagram illustrating a data example of a system specified value in the data transfer apparatus 1c. The system specified value table shown in FIG. 35 records a route attribute table monitoring period, a route table storage period, a minimum encounter accuracy value, and a parallel path determination threshold value calculation value. The “route attribute table monitoring period”, “route table storage period”, and “minimum encounter probability minimum value” are the same as those in the system specified value table shown in FIG.

  Here, with reference to FIG. 36 and FIG. 37, the specific example of the process by the path | route update part 4c before and after the node A encounters the node B is demonstrated. FIG. 36 is a diagram illustrating an example of the route table of the node A before the encounter between the node A and the node B, and FIG. 37 is a diagram illustrating an example of the route table of the node A after the encounter. In FIG. 36, it is assumed that node A has previously encountered node B and node R, has received the partner's route table, and has added it to its own route table.

  As shown in FIG. 36, before the encounter between the node A and the node B, there are one route via the node R and five routes via the node B as the route from the node A to the destination node Z. . Further, the encounter accuracy of one route passing through the node R is 0.525, and the encounter accuracy of five routes passing through the node B is 0.276, 0.276, 0.238, 0.186, 0.216. Higher than.

  As shown in FIG. 37, when the node A encounters the node B and becomes communicable at the present time, the path updating unit 4c causes the currently encountered node B to reach the same counterpart node Z in the route table of the node A. It is determined whether or not it matches with the leading node B on the five routes. The path update unit 4c performs the following process when the node B that is currently encountered matches the head node B on the five paths leading to the same counterpart node Z. In other words, the route update unit 4c indirectly uses any one of the five routes including the node B using the encounter probability of the node Z that can indirectly communicate with the five routes including the node B. The encounter accuracy of the node Z that can communicate is calculated. At this time, the route update unit 4c uses any of the five routes using the encounter accuracy exceeding the parallel route determination threshold among the encounter accuracy of the node Z that can indirectly communicate with the five routes including the node B. The encounter accuracy of the node Z that can communicate indirectly through one route is calculated. Further, the route update unit 4c deletes information about the five routes including the node B that matches the node B that is currently encountered from the route table, and sends information about the five routes deleted from the route table to the transmission control unit 5c. Notice. The encounter accuracy of the node Z that can indirectly communicate through any one of the five paths including the node B is calculated by, for example, the above equation (E), and the route table of the node A is updated.

For example, the route table shown in FIG. 36 is updated like the route table shown in FIG. 37 by the following processes (1) to (5).
(1) The route updating unit 4c selects the maximum value from the communication accuracy of the node Z that has become indirectly communicable through the five routes including the node B, and sets the parallel route determination threshold value to the selected maximum value. Multiplication is performed to calculate a parallel path determination threshold. Description will be made using an example of the system specified value shown in FIG. In the example illustrated in FIG. 35, the route update unit 4 c selects the maximum value 0.276 from the communication accuracy of the node Z that can indirectly communicate with the five routes including the node B, and sets the value to 0.276. The parallel path determination threshold value 0.193 is calculated by multiplying the parallel path determination threshold calculation value “70%”.
(2) The path update unit 4c uses any one of the five paths by using the encounter accuracy exceeding the parallel path determination threshold among the communication accuracy of the node Z that can indirectly communicate with the five paths including the node B. The encounter accuracy of the node Z that can communicate indirectly through one route is calculated. That is, four paths “BHZ” and “B-I−” that exceed the parallel path determination threshold 0.193 among the communication accuracy of the node Z that can indirectly communicate via the five paths including the node B. The encounter accuracy of the node Z is calculated using the encounter accuracy of “Z”, “BJZ”, and “BLZ”. Note that the information of the route “BKZ” that is equal to or less than the parallel route determination threshold is deleted from the route table.
(3) Indirect on any one of the four routes “BHZ”, “BIZ”, “BJZ”, and “BLS” including the node B Encounter accuracy of node Z at which communication is possible = 1− (1−0.276) × (1-276) × (1−0.238) × (1−0.216) = 0.686
The value of the calculation result of (3) corresponds to the entry data shown in (3) of FIG.
(4) The route update unit 4c stores information on the four routes “B-H-Z”, “B-I-Z”, “B-J-Z”, and “B-L-Z” including the node B. Delete from the route table shown in FIG. The route update unit 4c notifies the transmission control unit 5c of information on the four routes including the node B.

  As described above, the route update unit 4c uses any one of the plurality of routes by using the encounter accuracy of the indirect node that can indirectly communicate with the plurality of routes including the node that matches the other node. The route data is updated by calculating the encounter accuracy of the indirect node that can communicate indirectly. Then, when the route update unit 4c executes the above update process for all the partner nodes in the route data, the route update unit 4c records the updated route data in the route recording unit 7 as updated route data.

  Returning to FIG. 34, the transmission control unit 5 c determines whether or not to transmit the content data to another node detected by the communication unit 2 using the encounter probability in the updated route data of the route recording unit 7, and transmits it. The content data is transmitted to the determined other node. Specifically, when the updated route data of the route recording unit 7 includes a plurality of routes to the destination node of the content data, the transmission control unit 5c extracts and extracts the route having the highest encounter probability from each route. The content data is transmitted to another node using the route.

  When the transmission control unit 5c receives information on a plurality of routes deleted from the route data by the route update unit 4c from the route update unit 4c, the transmission control unit 5c adds the information on the plurality of routes to the content data to other nodes. Send. Hereinafter, content data to which information on a plurality of routes is added by the transmission control unit 5c is referred to as “transmission data”.

  Here, an example of the data structure of the transmission data will be described. FIG. 38 is a diagram illustrating an example of a data structure of transmission data. As shown in the figure, the transmission data includes destination information, transmission source information, multi-path transmission flag, multi-path transmission information, and actual data. “Destination information” is information indicating a destination node of transmission data. “Transmission source information” is information indicating a transmission source node of transmission data. The “multi-path transmission flag” is a flag indicating whether or not information on a plurality of paths is set in the transmission data. When “ON”, information on a plurality of paths is set in the transmission data. , “OFF” indicates that information of a plurality of routes is not set in the transmission data. “Multi-path transmission information” indicates information on a plurality of paths that are transmission targets of transmission data. “Real data” indicates actual content data to which information on a plurality of routes is added.

  For example, in the route table shown in FIG. 36, the route update unit 4c performs four routes “BHZ”, “BIZ”, “BJZ”, and “BLS”. Is deleted and notified to the transmission control unit 5c. The transmission control unit 5c sends the information of the four deleted routes “BHZ”, “B-I-Z”, “BJ-Z”, and “B-L-Z” to the route update unit 4c. Receive from. Then, the transmission control unit 5c adds the information of the four routes “BHZ”, “BIZ”, “BJZ”, and “BLZ” to the content data. To the other Node B that it encounters. FIG. 39 shows an example of transmission data in which four paths are added to the content data. As shown in the figure, the transmission control unit 5c sets the “multi-path transmission flag” of the transmission data to “node B = ON” indicating that information of four paths is set in the transmission data. In addition, the transmission control unit 5c adds four routes “BHZ”, “B-I-Z”, and “BJ-” as transmission targets of transmission data to the “multi-path transmission information” of the transmission data. Information of nodes H, I, J, and L to be transmitted next included in “Z” and “B-L-Z” is set.

  As described above, when the transmission control unit 5c receives the information on the plurality of routes deleted from the route data by the route update unit 4c from the route update unit 4c, the transmission control unit 5c adds the transmission data obtained by adding the information on the plurality of routes to the content data. Send to other nodes. As a result, other nodes that have received the transmission data are set to “multi-path transmission information” of the transmission data, instead of using their own path data to transmit data to the node on the path with the highest encounter accuracy. When one of the nodes is encountered, the transmission data is transferred to the node.

  Here, processing by another node that has received the transmission data will be described. FIG. 40 is a diagram for explaining processing by another node that has received transmission data. FIG. 40 shows a route table of the Node B that has received the transmission data shown in FIG. As shown in FIG. 40, when the node B that has received the transmission data confirms that the “multi-path transmission flag” is “ON”, the node B checks the path including the node set in the “multi-path transmission information”. . As a result, the node B does not transmit data to the node on the path with the highest encounter accuracy using the node B's own route table, but encounters one of the nodes set in the “multi-path transmission information”. In this case, the transmission data is transferred to the node. In the example of FIG. 40, since the path including the nodes H, I, J, and L set in the “multi-path transmission information” is checked, the node B is one of the nodes H, I, J, and L. If it encounters, transmit data to the node.

[Operation Example of Data Transfer Device According to Embodiment 4]
Next, an operation example of the data transfer apparatus according to the fourth embodiment will be described. FIG. 41 is a flowchart illustrating an operation example of the data transfer apparatus 1c according to the fourth embodiment. FIG. 41 is a processing procedure of data transfer processing by the data transfer device 1c when the communication unit 2 detects another node. In FIG. 41, processing steps corresponding to the processing steps of FIG. 29 are given the same numbers, and detailed descriptions thereof are omitted.

  As shown in FIG. 41, when the encounter accuracy is added to the route data (step S12), the route update unit 4c executes an updated route data generation process (step S13a). FIG. 42 is a flowchart illustrating a processing procedure of update route data generation processing. In FIG. 42, processing steps corresponding to the processing steps in FIG. 30 are assigned the same numbers, and detailed descriptions thereof are omitted.

  As shown in FIG. 42, when the process of step S134 is completed, the route update unit 4c determines whether or not the currently encountered node matches the first node on a plurality of routes reaching the same counterpart node in the route table. Is determined (step S141).

  If the currently encountered node does not match the first node on the route to the same counterpart node in the route table (No at Step S141), the route update unit 4c advances the process to Step S143. On the other hand, the path update unit 4c performs the following processing when the currently encountered node matches the leading node on the path to the same counterpart node. In other words, the route update unit 4c communicates indirectly through any one of the plurality of routes using the encounter accuracy of the indirect node that can indirectly communicate with the plurality of routes including the matching head node. The possible indirect node encounter accuracy is calculated (step S142).

  Subsequently, the path update unit 4c repeatedly executes the determination process in step S141 and the correction process in step S142 for all the counterpart nodes in the path data (No in step S143). Then, when the route update unit 4c executes the correction process of step S143 for all the partner nodes in the route data (Yes in step S143), the updated route data is recorded in the route recording unit 7 as updated route data (step S143). S135).

  Returning to the description of FIG. 41, when the operation mode is the normal mode (Yes at Step S21), the transmission control unit 5b refers to the updated route data of the route recording unit 7 to determine whether or not the content data needs to be transmitted. A data transmission determination process is executed (step S23a). FIG. 43 is a flowchart illustrating a processing procedure of data transmission determination processing. In FIG. 43, processing steps corresponding to the processing steps of FIG. 31 are given the same numbers, and detailed descriptions thereof are omitted.

  As shown in FIG. 43, when there are two or more routes to the destination node (Yes at Step S232, Yes at Step S234), the transmission control unit 5c currently encounters the node set in the multiple route transmission information. It is determined whether or not the current node matches (step S241). If the node set in the multi-path transmission information does not match the currently encountered node (No at Step S241), the transmission control unit 5c performs the following processing. That is, the transmission control unit 5c extracts a route having the highest encounter probability from the respective routes toward the destination node under the condition that “the size of the transmission data is smaller than the remaining HD amount in the route attribute table” (Step S1). S236), the process proceeds to step S237. On the other hand, if the node set in the multi-path transmission information matches the node currently encountered (Yes at step S241), the transmission control unit 5c transmits the content data without performing the process of step S236. Then, it is determined (step S239).

  When a route having the highest encounter probability is extracted under the condition that the size of the transmission data is smaller than the remaining HD amount in the route attribute table (Yes in step S237), the transmission control unit 5c Perform the process. That is, the transmission control unit 5c determines whether or not the node on the extracted route matches the currently encountered node (step S238). If the node on the extracted route matches the currently encountered node (Yes at step S238), the transmission control unit 5c is information on a plurality of routes deleted from the route data by the route update unit 4c. Is received from the route update unit 4c (step S242). When the information of the plurality of routes is not received from the route update unit 4c (No at Step S242), the transmission control unit 5c determines to transmit the content data (Step S239).

  On the other hand, when information on a plurality of routes is received from the route update unit 4c (Yes in step S242), the transmission control unit 5c sets the information on the plurality of routes in the transmission data with the “multi-path transmission flag” of the transmission data. It is set to “ON” indicating that it has been set (step S243). Subsequently, the transmission control unit 5c sets information on the next transmission target node included in the plurality of paths to be transmitted of the transmission data in the “multi-path transmission information” of the transmission data (Step S244), and the content data Is determined to be transmitted (step S239).

  Returning to the description of FIG. 41, when the content data after transmission is deleted from the content data recording unit 9 (step S26), the transmission control unit 5c performs the following processing. That is, the transmission control unit 5c refers to the route data in the route recording unit 7 and determines whether or not a check indicating that the route includes a node set in the “multiple route transmission information” is entered (step S1). S31). When the check is on (Yes at Step S31), the transmission control unit 5c deletes the check from the route data (Step S32), and advances the process to Step S27. On the other hand, when the check is not entered (No at Step S31), the transmission control unit 5c advances the process to Step S27.

  As described above, the data transfer device 1c according to the fourth embodiment indirectly communicates with any one of the plurality of routes when there are a plurality of routes ahead of the currently encountered node. The route data is updated by calculating the encounter accuracy of the possible indirect node. Then, the data transfer apparatus 1c determines whether or not data transmission is necessary using the updated route data. For this reason, the data transfer apparatus 1c can determine whether or not data transmission is necessary using the correct encounter accuracy after correction even when there are a plurality of routes ahead of the node being encountered. High data transfer can be realized.

  In addition, the data transfer device 1c according to the fourth embodiment uses any one of the plurality of routes by using an encounter accuracy exceeding a predetermined value among the encounter accuracy of the indirect node that can indirectly communicate with the plurality of routes. The encounter accuracy of an indirect node that can indirectly communicate with the route is calculated. Therefore, the data transfer device 1c can calculate the corrected encounter accuracy with higher accuracy using only the encounter accuracy exceeding a predetermined value, and can further improve the reliability of data transfer.

  In addition, the data transfer device 1c according to the fourth embodiment deletes information about a plurality of routes including a node that matches another node currently encountered from the route data. For this reason, the data transfer device 1c can prevent the enlargement of the route data, and can prevent the route data from squeezing the memory.

  Further, the data transfer device 1c according to the fourth embodiment adds information on a plurality of routes deleted from the route data to the content data and transmits the content data to the currently encountered node. Therefore, when another node that has received the data encounters a node on any one of a plurality of routes, the node can transfer the data to the node.

DESCRIPTION OF SYMBOLS 1, 1a, 1b, 1c Data transfer apparatus 2 Communication part 3 Control part 4, 4b, 4c Path | route update part 5, 5b, 5c Transmission control part 6 Memory 7 Path | route recording part 8 Storage 9 Content data recording part 11 Path | route attribute recording part 12 Interface unit 13 Input means 14 Output means

Claims (11)

A communication unit that detects other nodes within the communication range and performs data communication with the detected other nodes;
Information indicating a direct node which is another node detected by the communication unit and enabled to communicate directly; information indicating a route to the indirect node enabled to communicate indirectly via the direct node; A route recording unit that records route data including an encounter accuracy indicating a degree of certainty of communication with the direct node or the indirect node;
When the communication unit detects another node, if the other node matches a node on the route to the direct node and the indirect node of the route data, the direct node that matches the other node A route update unit that updates the route data by correcting the encounter accuracy of the direct node and the indirect node using the encounter accuracy of
A transmission control unit that controls whether or not to transmit data to the other node using the encounter probability of the direct node and the indirect node of the route data updated by the route update unit. A data transfer device.   The route update unit deletes the updated route data from the route recording unit when the communication unit no longer detects the other node after updating the route data. The data transfer device described in 1. A content data recording unit for storing content data to be transferred in association with information indicating a destination node of the content data;
When the communication unit detects the other node, the transmission control unit includes the case where the other node is the destination node of the content data, or the destination node is included in the indirect node of the route data 3. The data transfer device according to claim 1, wherein the content data is transmitted to the other node. The path update unit, when the communication unit detects another node, if the other node matches a node on a plurality of routes to the same indirect node in the path data, the other node The indirect communication that can be indirectly communicated through any one of the plurality of routes by using the encounter accuracy of the indirect node that has been indirectly communicable through the plurality of routes including the node that matches Update the path data by calculating the node encounter accuracy,
The transmission control unit controls whether to transmit data to the other node using the encounter probability of the direct node and the indirect node of the route data updated by the route update unit. The data transfer device according to claim 1.   The path update unit, when the communication unit detects another node, if the other node matches a node on a plurality of routes to the same indirect node in the path data, the other node Indirectly in any one of the plurality of routes by using an encounter accuracy exceeding a predetermined value among the encounter accuracy of the indirect node that can indirectly communicate with the plurality of routes including the node that matches The data transfer apparatus according to claim 4, wherein the encounter accuracy of the indirect node capable of communication is calculated.   The path update unit, when the communication unit detects another node, if the other node matches a node on a plurality of routes to the same indirect node in the path data, the other node The indirect communication that can be indirectly communicated through any one of the plurality of routes by using the encounter accuracy of the indirect node that has been indirectly communicable through the plurality of routes including the node that matches 6. The data transfer apparatus according to claim 4, wherein the encounter probability of a node is calculated, and information regarding the plurality of routes including a node that matches the other node is deleted from the route data. The route update unit notifies the transmission control unit of information on the plurality of routes deleted from the route data;
The data transfer apparatus according to claim 6, wherein the transmission control unit adds the information of the plurality of routes to the data and transmits the data to the other node. A data transfer method executed by a data transfer device that detects other nodes within the communication range and communicates with the detected other nodes,
Information indicating a direct node that is another node that can be directly communicated, information indicating a route to an indirect node that is indirectly communicable via the direct node, and the direct node or the indirect node Record the route data including the encounter accuracy indicating the degree of certainty of communication in the route recording unit,
When the data transfer device detects another node, if the other node matches the node on the route to the direct node and the indirect node of the route data, the direct node that matches the other node Updating the path data by correcting the encounter accuracy of the direct node and the indirect node using the encounter accuracy of the node;
A data transfer method comprising: controlling whether or not data is transmitted to the other node using the encounter probability of the direct node and the indirect node of the updated route data. When the data transfer device detects another node, if the other node matches a node on a plurality of routes to the same indirect node in the route data, the node that matches the other node The encounter accuracy of the indirect node that is indirectly communicable through any one of the plurality of routes is determined using the encounter accuracy of the indirect node that is indirectly communicable through the plurality of routes including By updating the route data,
The data transfer method according to claim 8, wherein whether or not data is transmitted to the other node is controlled by using the encounter probability of the direct node and the indirect node of the updated route data. To the data transfer device that detects other nodes within the communication range and communicates with the detected other nodes,
Information indicating a direct node that is another node that can be directly communicated, information indicating a route to an indirect node that is indirectly communicable via the direct node, and the direct node or the indirect node Record the route data including the encounter accuracy indicating the degree of certainty of communication in the route recording unit,
When the data transfer device detects another node, if the other node matches the node on the route to the direct node and the indirect node of the route data, the direct node that matches the other node Updating the path data by correcting the encounter accuracy of the direct node and the indirect node using the encounter accuracy of the node;
A data transfer program for executing a process of controlling whether or not to transmit data to the other node using the encounter probability of the direct node and the indirect node of the updated route data. When the data transfer device detects another node, if the other node matches a node on a plurality of routes to the same indirect node in the route data, the node that matches the other node The encounter accuracy of the indirect node that is indirectly communicable through any one of the plurality of routes is determined using the encounter accuracy of the indirect node that is indirectly communicable through the plurality of routes including By updating the route data,
11. The data transfer program according to claim 10, wherein whether or not data is transmitted to the other node is controlled using the encounter probability of the direct node and the indirect node of the updated route data.

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