JP2014086026A - Information transfer device and program thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow information transfer between different network areas even in a state where an environment is severely varied.SOLUTION: A terminal 100 generates network transition information and stores it in a storage unit 101 each time moving between network areas and, when being in a network area B, stores received transfer information in the storage unit 101 on reception of the transfer information transmitted from another node existing in the network area B. When the terminal 101 is moved from the network area B to a network area A, the terminal 101 determines whether the terminal itself is an unstable node or not on the basis of the stored transition information and, if it is an unstable node, reads out transfer information received and stored in the network area B where the terminal 101 existed before movement, and transmits it to a super node SND1 existing in the network area A where the terminal exists after movement.

Description

  The present invention relates to an information transmission device and a program thereof that enable information transmission even in a situation where the communication state is unstable, such as during a disaster.

  In recent years, attention has been focused on a resilient ICT (Information and Communication Technology) system that operates flexibly even in special situations such as disasters. In particular, the necessity of collecting necessary information in the event of a disaster leads to ensuring safety, so the necessity is increasing. However, in the event of a disaster, environment changes such as the instability of higher-level networks such as the Internet and frequent switching of terminals that make up the network are severe, and server-client communication widely used in normal operations There is a problem that it is difficult to cope with the system.

  On the other hand, as a technique for realizing information distribution that does not depend on environmental changes, a technique using a P2P (Peer-to-Peer) network has been proposed. For example, Non-Patent Document 1 introduces a technique in which network areas are divided in the same region and information can be transmitted and received in the same network area by each terminal (node) performing P2P communication. In addition, means for realizing information transmission between different network areas by selecting a representative terminal (super node) in each network area and transmitting / receiving information between the super nodes is also introduced.

Toshitaka Honda et al., “Proposal of Disaster Information Exchange System in P2P Environment”, IPSJ Research Report, EIP, [Electronic Intellectual Property / Social Infrastructure], 2009-EIP-46, vol. 13, pp.1 -7, 2009.

  However, in the technique described in Non-Patent Document 1, in order to transmit information between different network areas, it is necessary to use an upper network such as the Internet for connecting different networks. For this reason, although it is possible to cope with an environmental change such as switching of terminals constituting the network, information cannot be transmitted between different network areas in an environment where the communication state of the host network becomes unstable.

  The present invention has been made paying attention to the above circumstances, and an object of the present invention is to provide an information transmission apparatus and a program for transmitting information between different network areas even in a situation in which the communication environment changes drastically. There is to do.

  In order to achieve the above object, the first aspect of the present invention is to move between the first and second networks configured in different areas while moving within other areas of the first and second networks. In an information transmission apparatus that transmits information to and from a node, first, when the information transmission apparatus exists in the first network area and receives transmission information transmitted from another node existing in the area. In addition, the received transmission information is stored in a storage medium. Further, every time the information transmission apparatus moves between the network areas, information indicating changes in the stay history in each area is generated and stored. Then, when the information transmission apparatus moves from the first network area to the second network area, the own apparatus has moved in the past between the first and second networks based on the stored transition information. It is determined whether or not the node is an unstable node having a history, and when the own device is determined to be an unstable node, the transmission information received and stored in the first network area is read out and stored in the second network area. The data is transmitted to other existing nodes.

The first aspect of the present invention is characterized by comprising the following aspects.
In the first aspect, when determining whether or not the own device is an unstable node, a real number of networks having a stay history based on the stored transition information is equal to or greater than a first threshold set in advance. Whether there is a network in which the physical distance between the areas is more than a preset second threshold in a plurality of networks having a stay history and the first determination process for determining whether or not And a second determination process for determining whether or not the real number of networks having a stay history is 2 or more and whether or not the number of stays in the same network is greater than or equal to a preset third threshold value. At least one of the three determination processes is used to determine whether the own device is an unstable node.

  In the second aspect, when the received transmission information is stored in the storage medium, the priority of the received transmission information and the transmission information stored in the storage unit is calculated, and the storage unit Calculate free space. When the calculated free space is less than the fourth threshold, the transmission information having a lower priority than the received transmission information is deleted from the transmission information stored in the storage means, The received transmission information is stored in the storage medium.

  In a third aspect, as a means for calculating the priority, between the network where the own device was present when the received transmission information was stored in the storage medium and the network where the own device currently exists. First means for calculating the physical distance of the received information, second means for calculating the similarity between the received transmission information and the transmission information stored in the storage medium, and the received A third means for determining whether or not the newness of the transmission information is equal to or greater than a fifth threshold, and the reception is performed based on the calculation result and the determination result by the first, second and third means. The priority of the transmitted information is determined.

  In the fourth aspect, as a second means for calculating the similarity, a means for calculating the cosine similarity by converting the received transmission information into a space vector.

  According to one aspect of the present invention, when an information transmission apparatus receives and stores transmission information transmitted from another node in the first network area and then moves to the second network area, Is determined to be an unstable node having a history of movement between networks, and if it is an unstable node, the transmission information stored in its own device is read out and exists in the second network area. Sent to other nodes. In other words, in the state where a communication failure has occurred between the network area and the higher-level network connecting them, transfer of the transmission information between the networks through an information transmission device having a history of movement between the network areas Is possible.

  According to the first aspect, the real number of networks in which the information transmission device has stayed in the past, the physical distance between the networks, and the real number of networks in which the information transfer device has stayed in the past are equal to or greater than two. It is determined whether or not the device is an unstable node using at least one of the determination results as to whether or not the number of stays in the network is equal to or greater than a predetermined number. For this reason, it is possible to accurately determine whether or not the information transmission device is a node walking between network areas.

  According to the second aspect, each time the transmission information is received, the priority of the transmission information and the free capacity of the storage means are calculated. When the calculated free capacity is small, the priority is stored in the storage means. The transmission information having a lower priority than the received transmission information is deleted from the received transmission information, and the received transmission information is stored in the storage medium instead. Therefore, it is possible to more effectively utilize the limited storage capacity of the unstable node that mediates the transmission information.

  According to the third aspect, when calculating the priority, the distance between the networks before and after the movement, the similarity between the received transmission information and the transmission information stored in the storage medium, and the received The priority of the received transmission information is determined based on the newness of the transmission information. Therefore, it is possible to accurately determine the priority of the received transmission information.

According to the fourth aspect, the similarity between the received transmission information and the stored transmission information is converted into a space vector and calculated as its cosine similarity. For this reason, the similarity can be obtained relatively easily.
That is, according to the present invention, it is possible to provide an information transmission apparatus and a program for transmitting information between different network areas even in a situation where the environment changes drastically.

The figure used for description of the principle of the present invention. The figure which shows an example of the determination rule of the priority of information. The block diagram which shows the function structure of the information transmission apparatus which concerns on one Embodiment of this invention. The figure which shows an example of the network area transition information managed by the information transmission apparatus shown in FIG. The figure which shows an example of the transmission information memorize | stored in the information transmission apparatus shown in FIG. The flowchart which shows the whole process sequence and process content by the information transmission apparatus shown in FIG. 7 is a flowchart showing an unstable node determination processing procedure and processing contents in the processing procedure shown in FIG. 6. The flowchart which shows the priority calculation processing procedure and processing content of transmission information among the processing procedures shown in FIG. 7 is a flowchart showing a transmission information storage processing procedure and processing contents in the processing procedure shown in FIG. 6.

[principle]
In the present invention, the problem is solved by using “transition of stayed network area” and “priority of transmission information” of a terminal (node) staying in the network. Hereinafter, a description will be given with reference to FIG.
For example, in a P2P network, a node joins or leaves the network. Therefore, a history indicating which network area the subscriber has joined / leaved is left in each node. By using this information representing the “change of the network area to which the user belongs”, the node has been staying in the same network area for a long time (hereinafter referred to as “stable node”) or has been moving between different network areas. It is possible to determine whether it is a node (hereinafter referred to as an unstable node).

  Then, in the unstable node ND3 having a history of moving between the network areas, the transmission information generated in the network area B before the movement is stored, and the unstable node ND3 leaves the network area B and other information is stored. Is transferred to the network area A, and the transmission information stored in the network area B before the movement is read out and transmitted to the super node SND1 existing in the network area A after the movement.

  In this way, even if a communication failure occurs between the networks in the areas A and B and a higher-level network such as the Internet, information is transmitted to nodes belonging to networks in other areas. It becomes possible.

  On the other hand, transmission information is sequentially stored in unstable nodes that change over the network areas A and B, but there is a limit to the number of information that can be stored due to limitations such as storage capacity. Therefore, “information priority” is determined to determine information to be stored in the unstable node. For example, “physical distance between network areas”, “similarity of information”, and “newness of information” are used as parameters for obtaining the priority of information.

  First, the physical distance between network areas is a geographical distance between a newly staying network area and a network area that has stayed in the past. In the present invention, since it is assumed that connection to a higher-level network such as the Internet is impossible, the network area is composed of terminals having a close physical distance such as a wireless local area network (LAN) ad hoc network. Therefore, changing the network area to which it belongs is equivalent to changing the physical position on the earth, and the distance between the network areas is proportional to the magnitude of the change in position of the unstable node.

  The information similarity is a value indicating the degree of similarity between the newly received information and the information stored in the unstable node. If it is determined that they are similar, the possibility that the information indicates the same contents is high, and if they are not similar, the possibility that they indicate different contents is high. By utilizing this similarity, for example, dissimilar information is preferentially stored in the unstable node. In this way, information to be stored in the unstable node can be automatically determined, and effective information can be preferentially transmitted in consideration of the storage capacity of the notebook.

この場合、情報の類似度Simの取りうる値は−１≦Sim≦１であり、値が大きいほど類似していると見なす。 If the information is a document file, for example, a vector space method is used as a method for obtaining the similarity between the information. One of the received information is D, one of the information stored in the unstable node is E, the number of word types appearing in the information D and the information E is n, and the i-th word of the word types is wi, When the appearance frequencies of the word w in the information D and the information E are Dw and Ew, respectively, the similarity Sim (D, E) between the information D and the information E can be calculated by the following equation (1), for example.

In this case, the possible value of information similarity Sim is −1 ≦ Sim ≦ 1, and it is considered that the larger the value, the more similar.

  Subsequently, the newness of information refers to the newness of the time stamp when the information is registered or updated. It is determined that the time stamp is newer as it is closer to the current time, and that it is older as the time stamp is farther away.

  The “information priority” is calculated using the above “physical distance between network areas”, “similarity of information”, and “newness of information”. FIG. 2 is a diagram showing a case where information is prioritized in three stages of high, medium, and low. In this example, “physical distance between network areas is close and information similarity is low” has a high priority, “distant and low” has a medium priority, and “distant and high” has a priority. The degree is set low. Further, in the case of “close and high”, the newness of information is also taken into consideration, and if it is new, the priority is set high, and if it is old, the priority is set low.

  This priority determination example focuses on preferentially updating information that occurs physically nearby, and is particularly effective when there are many network areas in the vicinity and information changes frequently. This is an example. Here, increasing the priority of information as the physical distance between network areas increases is effective in transmitting information to various distant network areas as much as possible. Thus, by obtaining the priority of information using these parameters, it becomes easy to respond flexibly depending on what kind of information propagation is focused on. In addition, since physical distance between network areas, information similarity, and information novelty can be expressed numerically, they are treated as continuous values, such as the weighted average value of information priority. May be.

  If you want to calculate precise priorities even if calculation costs are applied, it is appropriate to use continuous values, and if you want to focus on the fact that calculation costs are not incurred even with rough priorities, use the above It is effective to use discrete values such as three levels (high, medium, and low). By doing so, it becomes possible to deal with whether to place importance on precision or calculation cost.

  As described above, by using “change of network area to which the user belongs” and “priority of information”, even in an environment where the communication state with the upper network such as the Internet is unstable, the unstable node Information transmission using movement between regional networks becomes possible.

[One Embodiment]
Hereinafter, an embodiment according to the present invention will be described with reference to the drawings.
(Constitution)
Here, the network system shown in FIG. 1 will be described as an example. FIG. 3 is a functional block diagram showing the configuration of the information transmission apparatus according to the embodiment of the present invention. In FIG. 1, nodes ND1 to ND4 correspond to this. The information transmission device includes mobile terminals (nodes) such as a mobile phone, a smart phone, a tablet terminal, and a notebook personal computer, and each user possesses the information transmission apparatus.

  The mobile terminal 100 includes, as functions necessary for realizing this embodiment, a storage unit 101, an unstable node determination unit 102, a priority calculation unit 103, a network area determination unit 104, and a super node determination unit 105. A super node function unit 106, a transmission information transmitting / receiving unit 107, a position information measuring unit 108, a communication interface 110, and a timer 111. Of these, each functional unit excluding the storage unit 101 is realized by causing a CPU (Central Processing Unit) (not shown) to execute an application program stored in a program memory (not shown).

  The storage unit 101 includes a transition information storage area 1011 and a transmission information storage area 1012. The transition information storage area 1011 is used to store information representing the stay history of the mobile terminal 100 in the network area, that is, the transition information of the network to which the mobile terminal 100 belongs. FIG. 4 shows an example thereof, in which the stay start time and end time, and the latitude and longitude data indicating the stay position are stored in association with the area name that is the identification information of the network area.

  The transmission information storage area 1012 is used for storing transmission information generated by the terminal itself and transmission information received from other terminals. FIG. 5 shows an example thereof, which includes registration time, registration network area name, latitude / longitude data, content data, and information indicating priority.

  The network area determination unit 104 receives network area information from the network when joining a network, and stores the received network area information in the storage unit 101. Then, a process start trigger is given to the super node determination unit 105, the unstable node determination unit 102, the transmission information transmission / reception unit 107, and the position information measurement unit 108. A function of storing the time in a corresponding item in the network area transition information storage area 1011 of the storage unit 101 and transmitting a start trigger to the super node determination unit 105 when leaving the network to which it belongs Have

  When receiving a start trigger from the network area determination unit 104 or the timer 111 that periodically generates a trigger, the super node determination unit 105 determines whether the own terminal is a terminal that should operate as a super node. When it is determined that the node should operate as a super node, a start trigger is given to the super node function unit 106. On the other hand, when it is determined that the super node function is currently operating but it is no longer necessary to operate as a super node, the super node function unit 106 has a function of giving a stop trigger.

  The super node function unit 106 activates the super node function when receiving the start trigger, and stops the super node function when receiving the stop trigger. The super node function includes a function for receiving transmission information from a terminal newly joined in the network area and distributing the received transmission information to other terminals already belonging to the network area, There is a function to know the terminals belonging to the network area. By using a super node having such a function, transmission / reception of transmission information in the network area can be performed smoothly.

  When receiving the start trigger, the unstable node determination unit 102 reads the network transition information from the storage unit 101, determines whether or not the terminal is an unstable node based on the network transition information, and The determination result is stored in the program memory. Since the unstable node determination flag does not need to be held until after the program ends, the capacity of the storage unit 101 is saved by storing it in the program memory.

  When the transmission information transmitting / receiving unit 107 receives the start trigger, the transmission information transmitting / receiving unit 107 receives the transmission information from other nodes existing in the network area where the terminal itself stays. Then, it is determined whether or not a determination flag indicating that the terminal is an unstable node is stored in the program memory. If the determination flag is not stored, the received transmission information is stored in the transmission information storage area 1012 of the storage unit 101. Remember. On the other hand, if it is stored, a start trigger is given to the information priority calculation unit 103. In addition, when joining the network, the transmission information stored in the transmission information storage area 1012 of the storage unit 101 is read out and transmitted to the terminal serving as the super node.

  The information priority calculation unit 103 includes a physical distance calculation unit 1021 between network areas, an information similarity calculation unit 1022, and an information freshness calculation unit 1023. Then, when a start trigger is received, the priority of the transmission information is calculated, and the calculated priority is stored in the transmission information storage area 1012 of the storage unit 101 in association with the transmission information.

  When the position information determination unit 108 receives a start trigger, the position information determination unit 108 measures the position of the terminal itself using, for example, GPS (Global Area Network), and the latitude / longitude data obtained by the positioning is stored in the network area of the storage unit 101. It is stored in the corresponding item in the transition information storage area 1011.

(Operation)
Next, the operation of the terminal 100 configured as described above will be described. FIG. 6 is a flowchart showing the entire processing procedure and processing contents of the information transmission operation by the terminal 100.

(1) Operation when Joining Network B First, in step S1, the terminal 100 monitors whether or not the terminal 100 has joined a new network by the network area determination unit 104. For example, when it is detected that the network area B shown in FIG. 1 has been joined, the network area information is received from the network in step S2, and the received network area information is stored in the network area transition information storage unit 101. Store in area 1011. Subsequently, in step S3, the position information measuring unit 108 measures the position of the terminal using GPS, and the latitude / longitude data obtained by this positioning is stored in the network area transition information storage area 1011 of the storage unit 101.

  Next, in step S4, the terminal 100 determines whether or not the terminal itself should operate as a super node by the super node determination unit 105. The determination as to whether or not to operate as a super node is based on the stability generally used in the super node type P2P (the power-on state is continuous for a predetermined period or more) and the storage capacity is a predetermined capacity or more. The parameter is such that the data processing speed of the CPU is equal to or higher than a specified speed. If these conditions are satisfied within the same network area, it is determined that the terminal is a terminal to be a super node, and the super node function unit 106 is operated.

  Next, in step S5, the terminal 100 activates the unstable node determination unit 102, and determines whether or not the own terminal is an unstable node under the control of the unstable node determination unit 102 as follows. . FIG. 7 is a flowchart showing the processing procedure and processing contents.

  That is, first, in step S501, the transition information of the network area where the terminal stayed in the preset period is read from the network transition information storage area 1011 of the storage unit 101. Subsequently, in step S502, if there is a real number of networks in which the terminal has stayed, that is, if there is a network area that has stayed twice or more, the number of network areas when the number of stays in the network area is counted as one is counted. To do. For example, as shown in FIG. 4, when four stay data are stored, since the four stay data have stayed twice in the area A, this is set as one time. The real number is 3.

  Then, it is determined whether or not the counted real number of the network is equal to or larger than a preset threshold value. If the result of this determination is that the real number of the network is greater than or equal to a preset threshold value, the unstable node determination unit 102 determines that the terminal is an unstable node in step S505, and an unstable node determination flag indicating that fact. Is stored in the program memory.

  On the other hand, it is assumed that the counted real number of the network is less than the threshold value. In this case, the unstable node determination unit 102 determines whether or not the read network area transition information includes a network area that is more than a preset distance from the currently staying network area. For example, if the stay data as shown in FIG. 4 is included in the network area transition information just read out, the distance between the network areas is calculated based on the latitude and longitude data included in the stay data. To do. Then, the calculated distance between the network areas is compared with a preset threshold value, and if there is a network area equal to or larger than the threshold value, it is determined in step S505 that the own terminal is an unstable node, and this is indicated. An unstable node determination flag is stored in the program memory.

  In addition, as a result of the determination in step S503, it is assumed that there is no network area in the network transition information whose distance between the network areas is equal to or greater than the threshold. In this case, the unstable node determination unit 102 proceeds to step S504 and sets the maximum number of occurrences of the same network area in advance in the network area transition information that has been read in such a manner that there are two or more types of network areas. It is determined whether or not there is more than the threshold number set. The maximum number of occurrences of the same network area refers to the maximum number of the same network areas included in the network area transition information.

  Taking FIG. 4 as an example, the maximum number of appearances of the same network area is two because the network area A has two appearances and the areas B and C each have one appearance. Here, a terminal that has stay history in at least two different network areas and repeatedly joins and leaves the same network area does not move from one network area to another. On the other hand, since it can be regarded as a terminal that stays regularly, it can be regarded as a node if it can play the role of an unstable node sufficient to entrust information propagation between network areas. Therefore, if the actual number of staying network areas is 2 or more and the maximum number of appearances of the same network area is greater than or equal to the threshold, it is determined in step S505 that the terminal is an unstable node, and an unstable node indicating that fact. The determination flag is stored in the program memory.

(2) Operation when receiving transmission information In a state where the terminal 100 is staying in the network area B shown in FIG. 1, transmission information addressed to itself is transmitted from another terminal staying in the network area B. Suppose. Then, the terminal 100 receives the transmission information via the communication interface 110 in step S7 under the control of the transmission information transmitting / receiving unit 107. In step S8, an unstable node determination flag is read from the program memory, and it is determined whether or not the own terminal is an unstable node based on the determination flag.

  If the result of the determination is that the terminal is an unstable node, the process proceeds to step S9, where the information priority calculation unit 103 is activated, and the priority of the received transmission information received by the priority calculation unit 103. Is calculated as follows. FIG. 8 is a flowchart showing the processing procedure and processing contents.

  That is, in step S901, the priority calculation unit 103 first determines whether there is information for which the priority has not yet been calculated if there is a plurality of the received transmission information. If there is uncalculated transmission information, the process proceeds to step S902, and one piece of uncalculated transmission information is selected.

  Next, for the selected transmission information, in step S903, the physical distance calculation unit 1021 between the network areas stores the currently staying network area and the selected transmission information when the selected transmission information is stored. Calculate the geographical distance between the network area where the person was staying. This geographical distance is calculated based on the latitude / longitude data included in the selected transmission information and the latitude / longitude data of the network area where the user is currently staying. Data representing the calculated physical distance between the network areas is stored in the working memory.

  In step S904, the information similarity calculation unit 1022 calculates the similarity between the selected transmission information and all the transmission information stored in the transmission information storage area 1012 of the storage unit 102. . The similarity of information is calculated as follows using, for example, a vector space method as described in the principle section.

そして、この算出された各類似度のデータを作業メモリに保存する。 That is, the selected transmission information is D, one of the transmission information stored in the transmission information storage area 1012 is E, the number of word types appearing in the transmission information D and the stored transmission information E is n, the word The i-th word of the type is wi, the appearance frequencies of the word w in the transmission information D and the transmission information E are Dw and Ew, respectively, and the similarity of information Sim between the transmission information D and the transmission information E (D, E ) Is calculated by the following equation (2).

The calculated similarity data is stored in the work memory.

  Next, in step S905, the transmission information having the lowest calculated similarity is selected, and the selected transmission information is compared with a preset threshold value to determine whether or not the threshold value is equal to or less than the threshold value. If the result of this determination is below the threshold value, the process moves to step S906, where it is determined whether or not the calculated physical distance between the networks is greater than or equal to a preset threshold value. If it is equal to or greater than the threshold value, in step S909, the priority of the selected transmission information is set to “medium”, and this is associated with the transmission information and stored in the work memory. On the other hand, if the physical distance between the networks is less than the threshold value, the priority of the selected transmission information is set to “high” in step S910, and this is associated with the transmission information and stored in the working memory. .

  On the other hand, it is assumed that the similarity of the selected transmission information is higher than a threshold value. If it does so, it will transfer to step S907 from step S905, and it will be determined here whether the physical distance between the calculated networks is below a threshold value. If it is higher than the threshold, in step S911, the priority of the selected transmission information is set to “low”, and this is associated with the transmission information and stored in the working memory.

  On the other hand, if the calculated physical distance between the networks is equal to or smaller than the threshold, the process proceeds to step S908, where whether or not the newness of the selected transmission information is equal to or larger than a preset threshold. Determine. If the result of this determination is greater than or equal to the threshold, in step S910, the priority of the selected transmission information is set to “high”, and this is associated with the transmission information and stored in the work memory. On the other hand, if it is less than the threshold value, the priority of the selected transmission information is set to “low” in step S911, and this is associated with the transmission information and stored in the working memory.

  Similarly, the priority calculation unit 103 calculates the priority for each of the received transmission information, and when the calculation of the priority for all the transmission information is completed, the process proceeds to step S10, and the received transmission information A process of storing information in the transmission information storage area 1012 of the storage unit 101 is executed as follows. FIG. 9 is a flowchart showing the processing procedure and processing contents.

  That is, first, the priority associated with the received transmission information is determined in step S1001. As a result, for the transmission information with the priority “low”, it is determined in step S1002 whether or not the free space in the transmission information storage area 1012 remains a predetermined amount or more. If it remains, the transmission information storage area is determined in step S1003. 1012 is stored. On the other hand, if there is no free space, it is discarded without being stored.

  Next, as a result of the determination in step S1001, for the transmission information with the priority “medium”, it is determined in step S1004 whether or not the free space in the transmission information storage area 1012 remains over a predetermined amount. For example, it is stored in the transmission information storage area 1012 in step S1005. On the other hand, if there is no free space equal to or larger than the predetermined amount, the transmission information stored in the transmission information storage area 1012 in step S1006 has a priority lower than “medium”, that is, a transmission with a priority of “low”. It is determined whether there is information. If transmission information having a priority of “low” is found, the transmission information is deleted in step S1007, and then the received transmission information having a medium priority is stored in step S1008. .

  As a result of the determination in step S1001, for the transmission information with the priority “high”, in step S1009, it is determined whether or not the free space in the transmission information storage area 1012 remains a predetermined amount or more. In step S1010, the information is stored in the transmission information storage area 1012. On the other hand, if there is no free space equal to or larger than the predetermined amount, the priority is lower than “high” in the transmission information stored in the transmission information storage area 1012 in step S1011, that is, the priority is “low” or “ It is determined whether there is transmission information of “medium”. If transmission information with a priority of “low” or “medium” is found, the transmission information with the lowest priority is deleted in step S1012, and then the received information is received in step S1013. The transmission information having a high priority is stored.

(3) Operation when a transmission request for transmission information is received from another terminal It is assumed that a transmission information transmission request is sent from another terminal in the same area while staying in the network area B. When the terminal 100 detects reception of this transmission request in step S11, the terminal 100 activates the transmission information transmitting / receiving unit 107 in step S12. Then, under the control of the transmission information transmitting / receiving unit 107, the corresponding transmission information is read from the transmission information storage area 1012 of the storage unit 101, and the read transmission information is transmitted from the communication interface 110 to the requesting terminal. .

(4) Operation when leaving the network Assume that the terminal 100 leaves the network area B and cannot receive radio waves from other terminals staying in the network area B. Then, the terminal 100 determines that the terminal 100 has left the network area B in step S13 under the control of the network area determination unit 104, and proceeds to step S14. In this step S14, the departure time is written as the end time in the corresponding stay data stored in the network area transition information storage area 1011 of the storage unit 101, and a standby state is entered until the next event occurs.

(5) Operation when moving from network area B to network area A It is assumed that after the terminal 100 leaves the network area B, it moves to the network area A and tries to join. Similarly to the case described in (1) above, the terminal 100 monitors whether or not the own terminal has joined the network by the network area determination unit 104 in step S1. Then, when it is detected that the network area A has been joined as shown in FIG. 1, the storage processing of the network area information and the measurement of the position information are performed in steps S2 to S5 as in the case described in (1). After performing the process and the super node determination process, the unstable node determination process is performed.

  As a result of the unstable node determination process, if the own terminal is an unstable node, all the information stored in the transmission information storage area 1012 of the storage unit 101 under the control of the transmission information transmitting / receiving unit 107 in step S6. Read the transmission information. Then, the read transmission information is transmitted from the communication interface 110 to the super node SND1 in the network area A. When the super node SND1 is not set in the network area A, it may be broadcast to all terminals staying in the network area A.

  Accordingly, the transfer information received and stored by the terminal 100 in the network area B before the movement due to the movement of the unstable terminal 100 between the networks is the super node SND1 or other terminals ND1, ND2 existing in the network area A of the movement destination. Is transmitted to.

(effect)
As described in detail above, in one embodiment, each time the terminal 100 moves between network areas, information indicating the transition of the stay history in each area is generated and stored in the storage unit 101, and the network area B When the transmission information transmitted from other nodes existing in the area B in the existing state is received, the received transmission information is stored in the storage unit 101. Then, when the terminal 101 moves from the network area B to the network area A, it is determined based on the stored transition information whether the own device is an unstable node. The transmission information received and stored in the network area B is read out and transmitted to the super node SND1 existing in the network area A after movement.

  Therefore, even if a communication failure or the like occurs between the network areas A and B and a higher level network such as the Internet due to a disaster, for example, the network areas A and B are utilized by using the movement of the terminal 100 that is an unstable node between networks. It is possible to transmit information between them.

  Whether the terminal 100 is an unstable node is determined based on the real number of networks in which the terminal 100 has stayed in the past, the physical distance between networks, and the real number of networks in which the terminal 100 has stayed in the past. Is equal to or greater than 2, and the determination result of whether or not the number of stays in the same network is equal to or greater than a predetermined number is used. Therefore, it can be accurately determined whether or not the terminal 100 is a node walking between the network areas A and B.

  Further, each time the transmission information is received, the priority of the transmission information and the free capacity of the transmission information storage area 1012 of the storage unit 101 are calculated. If the calculated free capacity is less than a predetermined amount, the storage information is stored. The transmission information having a lower priority than the received transmission information is deleted from the transmission information stored in the unit 101, and the received transmission information is stored in the storage unit 101 instead. Therefore, it is possible to more effectively utilize the limited storage capacity of the unstable node that mediates the transmission information.

  When calculating the priority, the distance between the networks before and after the movement, the similarity between the received transmission information and the transmission information stored in the storage medium, and the newness of the received transmission information. Based on the above, the priority of the received transmission information is determined. Moreover, a vector space method for document files is used as a method for calculating the similarity between transmission information. Therefore, it is possible to accurately determine the priority of the received transmission information.

[Other Embodiments]
The present invention is not limited to the above embodiment. For example, in the above embodiment, the terminal 100 that is an unstable node has been described as an example in which the stored transmission information is transmitted to the super node SND1 in the network area A of the movement destination. However, the terminal 100 belongs to the network area A. Broadcast transmission may be made to all the nodes ND1, NS2, and SND1.

  In addition to the P2P network, the present invention may be applied to a network that establishes a fixed communication area in a specific area, such as a wired LAN and a wireless LAN, and the number and types of other networks and types of nodes. Various processing procedures and processing contents in the configuration, transmission / reception control of transmission information, priority calculation, unstable node determination, and the like can be variously modified without departing from the scope of the present invention.

  In short, the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment.

  ND1 to ND4 ... node, SND1, SND2 ... super node, NW ... network, 100 ... mobile terminal (node), 101 ... storage unit, 1011 ... network transition information storage area, 1012 ... transmission information storage area, 102 ... unstable node , 103 ... priority calculation unit, 1021 ... physical distance calculation unit between network areas, 1022 ... information similarity calculation unit, 1023 ... information freshness calculation unit, 104 ... network area determination unit, 105 ... super node determination 106: Super node function unit, 107: Transmission information transmitting / receiving unit, 108 ... Location information measuring unit, 110 ... Communication interface, 111 ... Timer.

Claims (6)

An information transmission device that performs information transmission with other nodes existing in areas of the first and second networks while moving between first and second networks configured in different areas,
A transition information management means for generating and storing information representing a transition of a stay history in an area of the network every time the network moves.
Transmission information receiving means for storing the received transmission information in a storage medium when receiving the transmission information transmitted from another node existing in the area in the state existing in the area of the first network; ,
When moving from the first network area to the second network area, the own device has a history of moving between the first and second networks in the past based on the stored transition information. Determining means for determining whether the node is an unstable node;
When it is determined that the own device is an unstable node, the transmission information received and stored in the area of the first network is read and transmitted to other nodes existing in the area of the second network. Means for transmitting information.   Based on the stored transition information, the determination means has stayed with a first determination process for determining whether or not a real number of a network having a stay history is equal to or more than a first threshold set in advance. There is a second determination process for determining whether or not there is a network whose physical distance between areas is more than a preset second threshold in a plurality of networks having a history, and a stay history Using at least one of the third determination processes for determining whether or not the real number of networks is 2 or more and the number of stays in the same network is greater than or equal to a preset third threshold, The information transmission apparatus according to claim 1, wherein it is determined whether or not is an unstable node. The transmission information receiving means includes
Means for calculating the priority of the received transmission information and the transmission information stored in the storage means;
Means for calculating the free capacity of the storage means;
When the calculated free space is less than a fourth threshold, the transmission information stored in the storage means deletes transmission information having a lower priority than the received transmission information, and instead 3. The information transmission apparatus according to claim 1, further comprising means for storing received transmission information in the storage medium. The means for calculating the priority is:
A first means for calculating a physical distance between a network area where the device itself was present at the time of storing the received transmission information in the storage medium and a network area where the device is present;
A second means for calculating a similarity between the received transmission information and the transmission information stored in the storage medium;
Third means for determining whether the received transmission information is newer than a fifth threshold;
4. An information transmission apparatus according to claim 3, further comprising means for determining a priority of the received transmission information based on a calculation result and a determination result by the first, second and third means. .   5. The information transmission apparatus according to claim 4, wherein the second means for calculating the similarity calculates the cosine similarity by converting the received transmission information into a space vector.   The program which makes the computer with which the said information transmission apparatus performs the process of each means with which the information transmission apparatus in any one of Claims 1 thru | or 5 is provided.

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