JP2009152995A - Communication system, transmission terminal used for communication system, relay terminal used for communication system, communication method in communication system and computer program used for communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a publication-side terminal to transmit information while designating a desired subscription-side terminal in a system for performing data distribution services (DDS)-based communications. <P>SOLUTION: Each of relay terminals 2-4 includes a table 15 for storing therein one of a plurality of priorities ranked among the relay terminals 2-4 and a means for transmitting and receiving control information required for performance of communication procedures determined by DDS between a transmitting terminal 5 and a receiving terminal 1. The transmitting terminal includes a means for transmitting and receiving the control information to/from each of the relay terminals 2-4, a storage section 17 for storing address information of the relay terminals 2-4, respectively, and a table 18 for storing therein priorities of the relay terminals 2-4 read from the respective tables 15 of the relay terminals 2-4 by the transmitting and receiving means. The transmitting terminal 5 selects any one relay terminal 2 based on the priorities in the table 18 and transmits information to the relay terminal 2, and the relay terminal 2 transmits the information to the receiving terminal 1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a communication system suitable for a Publish / Subscribe (publish-subscribe) type communication system, a transmission terminal used in the communication system, a relay terminal used in the communication system, a communication method in the communication system, and The present invention relates to a computer program used in the communication system.

  DDS (Data Distribution Service) is known as a standard for a publish-subscribe communication model. In the DDS specification, information is identified by topic, and this topic is used as a destination of information. The subscription side terminal registers the topic to be received in the server, and the publishing side terminal transmits information about only its own topic to the server. The information transmitted by the publisher terminal is distributed to a plurality of subscriber terminals that have registered topics.

  In a DDS publish-subscribe communication model, a sender (publisher) generates data called a topic in a virtual data space. This communication model has a mechanism in which a sender sends data called a sample to a receiver (subscriber) who declares that he / she is interested in the topic. Thereby, an application that can realize m-to-n data communication can be easily produced. However, the DDS does not have a function of transmitting information to a single optimal terminal. The communication application of the sender terminal cannot directly specify the destination and send data to the receiver terminal.

  Therefore, in the communication system using DDS, in order to specify the destination, a topic that allows the sender terminal to identify the receiver terminal is created, and all the samples that the sender terminal has published about the topic are created. It is necessary to use a technique for transmitting to the recipient terminal.

  Each topic from a plurality of receiver terminals and each topic from a plurality of sender terminals are inquired by each of these receiver terminals and each sender terminal, and in a state where addressees are designated, Multiple data communications can be performed.

With regard to technology for connecting terminals via multiple communication paths formed by multiple communication media, conventionally, in a network in which multiple alternative communication paths coexist, communication is performed by selecting the optimal communication path according to the communication state. A relay device and an optimum communication path selection method have been proposed (see Patent Document 1).
JP 2006-135593 A

  However, in this method, it is necessary to generate one topic for each destination terminal. When there is a change such as increase / decrease in the number of terminals in the transmission source, in order to perform appropriate communication according to this number, the server must prepare topics for the number of sender terminals. Each communication application of the sender terminal and the receiver terminal must manage conditions such as which topic the sample is to be transmitted, and in order to perform this management, the sender terminal and the receiver terminal A communication control unit must be installed on each communication application side.

  For example, when the communication system has four sender terminals and four receiver terminals, and each receiver terminal generates and registers one topic in the server, each sender terminal also has these topics. It is necessary to generate four topics on the server corresponding to each. When any sender terminal sends a sample to any receiver terminal, a communication procedure between the sender terminal and the receiver terminal is determined in advance, and processing in accordance with this procedure is performed on these terminals. Each communication application needs to be executed. In this method, communication management and communication settings must be performed between communication applications of each terminal.

  In addition, as another method for realizing the designation of the destination, a time stamp is added to information transmitted by a plurality of sender terminals, and the information is transmitted to all terminals and then received. It is conceivable that the receiver terminal receives the same information from a plurality of sender terminals, and finally the receiver side deletes the duplicate information. However, even if this method is used, there are disadvantages such as complication of communication application implementation or transmission band compression.

  Therefore, in view of the above problems, the present invention enables a publishing-side terminal to designate a desired subscription-side terminal and transmit information in a publish-subscribe communication system, and the subscription-side terminal can be transmitted from a plurality of publishing-side terminals. Communication system capable of avoiding duplicate reception of same data and reducing transmission band compression, transmission terminal used in communication system, relay terminal used in communication system, communication method and communication in communication system An object is to provide a computer program used in the system.

  In order to solve such a problem, according to claim 1 of the present invention, a transmitting terminal that transmits information based on DDS and generates a topic for this information, and a receiving terminal that receives information corresponding to the topic, A plurality of relay terminals that are hierarchically connected to the transmission terminal and the reception terminal and relay information from the transmission terminal to the reception terminal, and each relay terminal includes the plurality of relay terminals. A first table storing one of a plurality of priorities ordered among relay terminals, and control information necessary for executing a communication procedure defined by the DDS, the transmission terminal and the reception A first transmission / reception unit that transmits / receives data to / from a terminal, and the transmission terminal transmits / receives control information necessary for execution of the communication procedure to / from each relay terminal; The first A storage unit for storing address information of each relay terminal acquired via the transmission / reception unit and the second transmission / reception unit, and each relay terminal via the first transmission / reception unit and the second transmission / reception unit And a second table for storing the priorities of these relay terminals read from the respective first tables, and the transmitting terminal selects any one of the relays based on the priorities of the second table. A communication system is provided in which a terminal is selected, information is transmitted to the selected relay terminal using the address information, and the selected relay terminal transmits the information to the receiving terminal. The

  According to claim 2 of the present invention, an information generation unit that generates information, information, a topic about the information, and control information necessary for executing a communication procedure defined by the DDS are transmitted to the network together with the transmission terminal. A transmission / reception unit that respectively transmits / receives data to / from a plurality of relay terminals, a storage unit that stores address information of these relay terminals received by the transmission / reception unit, and the plurality of relay terminals via the transmission / reception unit A table for storing priorities ordered among these relay terminals received from each of the relay terminals, and selecting any one relay terminal based on each priority and using the address information for the selected relay terminal And a control unit that instructs the transmission / reception unit to transmit information. That.

  According to claim 3 of the present invention, information transmitted from a transmission terminal that forms a network together with the relay terminal, a topic about this information, and control information necessary for execution of a communication procedure defined by DDS, A transmission / reception unit that transmits and receives between the transmitting terminal and the receiving terminal that forms this network, and all of these relays that are received from each of the relay terminal and a plurality of other relay terminals that form the network together with the relay terminal There is provided a relay terminal used in a communication system, comprising: a table that stores one priority among a plurality of priorities ordered in advance between terminals.

  According to claim 4 of the present invention, transmitting terminals that transmit information based on DDS and generate a topic for this information are divided into this transmitting terminal and a receiving terminal that receives information corresponding to the topic, respectively. From a plurality of relay terminals that are connected to each other and relay information from the transmitting terminal to the receiving terminal, respectively, and obtain one priority among a plurality of priorities ordered among these relay terminals And a step in which the transmitting terminal selects any one of the plurality of relay terminals based on the priority, and the transmitting terminal transmits information to the selected relay terminal. And a step in which the selected relay terminal transmits this information to the receiving terminal. A method is provided.

  According to claim 5 of the present invention, a transmitting terminal that transmits information based on DDS and generates a topic for this information includes the transmitting terminal and a receiving terminal that receives information corresponding to the topic, respectively. From a plurality of relay terminals that are hierarchically connected to relay information from the transmitting terminal to the receiving terminal, and each of the priorities ordered among the relay terminals is set to one priority. Obtaining, a step in which the transmitting terminal selects any one of the plurality of relay terminals based on the priority, and the transmitting terminal selects the selected relay terminal. Transmitting the information and transmitting the information to the receiving terminal by the selected relay terminal, the transmitting terminal, the receiving terminal, and a plurality of A computer program for use in a communication system, characterized in that to be executed by a computer provided in each of the relay terminal is provided.

  According to the present invention, in a communication system that performs communication based on DDS, a transmission terminal as a publishing side terminal transmits information to a specific relay terminal among a plurality of relay terminals that are subscription side terminals. As a result, it is possible to avoid the occurrence of duplicate reception of the same data from a plurality of transmitting terminals at the receiving terminal, and to reduce the load on the transmission band.

  FIG. 1 to FIG. 6 are shown below regarding a communication system according to an embodiment of the present invention, a transmission terminal used in the communication system, a relay terminal used in the communication system, a communication method in the communication system, and a computer program used in the communication system. The description will be given with reference. In the drawings, the same portions are denoted by the same reference numerals, and redundant description is omitted.

  In the communication system according to an embodiment of the present invention, a packet is sequentially relayed between a plurality of terminals, whereby a sender terminal that is a publishing terminal is connected to a receiver terminal that is a subscriber terminal. A publish-subscribe communication system for transmitting information. This communication system is a wireless communication system in which these wireless terminals perform wireless communication via an ad hoc network formed by a plurality of wireless terminals, for example. One of the terminals generates a topic and publishes a sample. Each terminal is equipped with middleware for executing communication procedures in accordance with the DDS standard or the DDS specification. By communicating between these middlewares, the terminal on the subscribing side that declares that it is interested in this topic You are supposed to receive samples.

  As an example, this communication system is applied to an air traffic control system. Airplane flights are used as topics. The sender terminal in each location registers the flight of the airplane in the server device, so that information such as the departure time, arrival time or flight track of this airplane is associated with this topic. A receiver terminal operated by an operator inquires information about a flight of a desired airplane, and thereby can receive information desired by the operator in real time.

  FIG. 1 is a diagram illustrating an arrangement example of terminals in a communication area in the communication system according to the present embodiment. This communication system includes terminals 1 to 8 that are movable and perform wireless communication. The terminal 1 and the terminal 2 are located in a place where the terminal 1 and the terminal 2 can directly perform wireless communication with each other at a certain time, and the terminal 3 can also perform direct wireless communication with the terminal 1. The terminal 4 is also located in a place where it can directly wirelessly communicate with the terminal 1. At the same time, the terminal 2, the terminal 3, and the terminal 4 are all located in a place where the packet can be transferred to the terminal 1 within one hop. The communicable range D-1 represents a range in which direct wireless communication is possible between the terminal 1 and the three terminals 2 to 4. Terminals 2 to 4 form one group, and terminal 1 is located outside the communication range of this group. Hereinafter, a group to which the terminal 1 belongs (here, one terminal 1 belongs) is called a terminal type A, and a group to which the terminals 2 to 4 belong is called a terminal type B.

  Also, at the same time, the terminal 5 is located where the wireless communication can be performed directly with the terminals 2 to 4 belonging to the terminal type B, and the terminal 6 is mutually connected with the terminals 2 to 4. The terminal 7 is located where direct wireless communication is possible, the terminal 7 is located where mutual wireless communication is possible between the terminals 2 to 4, and the terminal 8 is directly wirelessly connected between the terminals 2 to 4. It is located where communication is possible. The terminal 5, the terminal 6, the terminal 7, and the terminal 8 are all located at a position where packets can be transferred within one hop with the terminals 2 to 4 belonging to the terminal type B at this time. The communicable range D-2 represents a range in which direct wireless communication is possible between the three terminals 2 to 4 and these terminals 5 to 8. Terminals 5 to 8 also form a group. A group to which these terminals 5 to 8 belong is called terminal type C.

  That is, in the range of D-1 in FIG. 1, the terminal 1 of the terminal type A and the terminals 2 to 4 of the terminal type B are in a communicable state. In the range of D-2, FIG. 1 shows that the terminals 2 to 4 of the terminal type B and the terminals 5 to 8 of the terminal type C can communicate with each other.

  In this communication system, a packet created by any terminal 5, 6, 7 or 8 of terminal type C is transmitted to any terminal 2, 3 or 4 of terminal type B, and the terminal 2, 3 or 4 is transmitted. Transmits this packet to the terminal 1. When terminal type C transmits information to terminal type A via terminal type B, terminal 1 of terminal type A has terminals 2 to 4 of terminal type B and terminals 5 of terminal type C. The information is collected from the 8th.

  FIG. 2 is a block diagram of three terminals including a transmission terminal and a relay terminal according to the present embodiment. Elements having the same reference numerals as those described above in FIG. 2 represent the same elements.

  The terminal 1 includes an information reception processing unit 9 that receives a packet from the terminal 2, 3, or 4 and extracts a sample as information, and an information accumulation unit 10 that collects and stores the sample. A wireless reception device is used for the information reception processing unit 9, and a storage device is used for the information accumulation unit 10.

  Further, the terminal 1 includes a control information transmission / reception unit 11 that transmits / receives information necessary for DDS communication control, and a QoS information storage unit 12 that stores DDS QoS (Quality of Service) information. As the QoS information, the terminal 1 stores information such as a management period and an expiration date of the QoS packet. For example, the QoS information storage unit 12 stores the contents of processing such as always sending a packet regardless of whether the wireless environment is good or not, and temporarily holding the data of the sent packet. When the control information transmitting / receiving unit 11 reads this QoS information, the terminal 1 controls packet transmission / reception according to the contents of the QoS information.

  The terminal 2 is a relay terminal according to the present embodiment. The terminal 2 is pre-ordered between the information transmission unit 14 that receives from the terminal 5, 6, 7 or 8, and transmits the information accumulated in the information accumulation unit 10 to the terminal 1, and the terminals 2, 3 and 4. And a terminal priority information table 15 for storing the priority of the terminal 2.

  FIG. 3 is a diagram showing an example of records stored in the terminal priority information table 15. One record written in the terminal priority information table 15 associates the terminal name of the terminal 2 with the priority. In the communication system according to the present embodiment, for example, the value 9, the value 10, and the value 3 are predetermined as the priorities for the three terminals 2, 3, and 4 belonging to the terminal type B, respectively. How to determine the priority relationship depends on the communication status and terminal performance. The communication state refers to data obtained by quantifying the magnitude of the received electric field intensity that varies depending on the distance between terminals and the quality of the radio wave transmission / reception environment. The terminal performance refers to the antenna gain and the magnitude of transmission power.

  The control information transmission / reception unit 11 of the terminals 2 to 4 can notify the priority of each terminal priority information table 15 to the terminals 5 to 8. In other words, the communication system according to the present embodiment allows the publishing side terminal to select the transmission destination terminal without providing a mechanism for determining the priority by providing the subscription side terminal with a mechanism for determining the priority. Is possible.

  Note that a storage device is used for the terminal priority information table 15, and a wireless transmission device is used for the information transmission unit 14. The terminal 2 is also provided with an information reception processing unit 9, an information accumulation unit 10, a control information transmission / reception unit 11, and a QoS information storage unit 12.

  The configurations of the terminal 3 and the terminal 4 are the same as the configuration of the terminal 2.

  The terminal 5 belonging to the terminal type C is a transmitting terminal according to this embodiment. The terminal 5 includes an information generation unit 16 that generates information, a terminal information table (storage unit) 17 that stores addresses of all terminals 2, 3, and 4 belonging to the terminal type B, and terminals 2, 3, and 4. And a priority information table 18 for storing the priorities set in advance for the terminals 2, 3 and 4 read from each terminal priority information table 15.

  FIG. 4 is a diagram showing an example of the terminal information table 17. In the terminal information table 17, addresses that can uniquely identify the terminals 2 to 4 belonging to the terminal type B are stored in association with these terminals 2 to 4. A storage device is used for the terminal information table 17.

  FIG. 5 is a diagram showing an example of records stored in the priority information table 18. Whether one record written in the priority information table 18 is a state in which the names of all the terminals 2 to 4 belonging to the terminal type B and the communication between these terminals 2 to 4 are connected. A value of “0” or “1” indicating “” is associated with priorities ordered among these terminals 2 to 4. A storage device is used for the priority information table 18.

  The terminal 5 reads whether the value of the transmittable terminal bit for the partner relay terminal that is the communication partner is “1” or “0”, and performs wireless communication with this partner relay terminal or wireless communication according to this value. It is determined whether or not to perform. In the communication system according to the present embodiment, since the terminals 1 to 8 always move in the wireless environment, there may be a situation where the wireless connection between the terminal 5 and the terminals 2 to 4 is disconnected. If the wireless connection with the partner relay terminal is successful, the terminal 5 updates the transmittable terminal bit to “1”. The terminal 5 updates the transmittable terminal bit to “0” when the wireless connection with the partner relay terminal fails.

  The terminal 5 in FIG. 2 also includes an information transmission unit 14, a control information transmission / reception unit 11, and a QoS information storage unit 12. The control information transmission / reception unit 11 also functions as a control unit of the transmission terminal according to the present embodiment.

  The configurations of the terminals 6, 7 and 8 are the same as the configuration of the terminal 5.

  In the communication system according to the present embodiment, the functions of the control information transmission / reception unit 11 and the QoS information storage unit 12 of the terminal 1 are realized by middleware installed in the terminal 1. The control information transmission / reception unit 11 includes a storage unit 13 that stores topics from the terminal 2 and manages the data space of the storage unit 13. The functions of the control information transmission / reception unit 11 and the QoS information storage unit 12 of the terminal 2 are also realized by the middleware installed in the terminal 2, and the functions of the control information transmission / reception unit 11 and the QoS information storage unit 12 of the terminal 3 are also realized. This is realized by middleware installed in the terminal 3. Further, this communication system is provided with a server (not shown), and the same middleware having the same functions as those of the control information transmission / reception unit 11 and the QoS information storage unit 12 is also mounted on this server.

  Thereby, the middleware of the terminal 1 and the middleware of the terminals 2 to 4 transmit and receive control information such as topics. Control information is transmitted and received between the middleware of the terminals 2 to 4 and the middleware of the terminals 5 to 8 via the middleware.

  The terminals 1 to 8 of the communication system according to the present embodiment are equipped with communication application software and the above middleware. Of these two, the communication application implements the functions of the information accumulation unit 10 of the terminal 1, the information transmission unit 14 and the information accumulation unit 10 of the terminal 2, and the information transmission unit 14 and the information generation unit 16 of the terminal 5. Has been. On the information transfer path composed of the information accumulation unit 10 of the terminal 1, the information transmission unit 14 of the terminal 2, the information accumulation unit 10 of the terminal 2, the information transmission unit 14 of the terminal 5, and the information generation unit 16 of the terminal 5. Samples are sent and received so that information is sent from the terminal type C side to the terminal type A side.

  Further, the middleware of each of the terminals 1 to 8 notifies the server middleware of the terminal name or terminal address of the information destination. In the communication system according to the present embodiment, the middleware of all the terminals 1 to 8 and the middleware of the server are exchanged instead of sending an instruction for the communication application installed in the terminals 1 to 8 to send to the terminal name or address. Exchanges information to reduce the load on communication applications.

  In this communication system, since each middleware manages the data space of the storage unit 13 in the control information transmission / reception unit 11 of all the terminals 1 to 8, when viewed from these terminals 1 to 8, the other party sending data is a server It is possible for the upper application to request the middleware to send / receive information to / from the middleware in each of the terminals 1 to 8 without distinguishing whether the terminal is one of the terminals 1 to 8. When viewed from each of the terminals 1 to 8, topics can be exchanged by one process of sending data only to middleware managing a space in which information is stored. The transmission terminal according to the present embodiment and the relay terminal according to the present embodiment both determine a data destination and exchange data by communication between middleware. The terminals 1 to 8 send and receive data such as topics by giving commands to the control information transmission / reception unit 11 in this middleware.

  In the communication system according to the present embodiment having the above-described configuration, the terminal 5 acquires the priorities of the terminals 2 to 4. In advance, the user sets priorities for all terminals 2 to 4 of terminal type B, and the respective priorities are held in the respective terminal priority information tables 15 of the terminals 2 to 4. In addition, the user assigns each priority so that there is no overlapping of priority among the terminals 2 to 4. In order for the terminal 5 to specify the destination for the terminals 2 to 4 and perform transmission, the terminal 5 determines the transmission destination of one of the terminal types B based on the priority of the terminals 2 to 4. As for the terminals 6 to 8 belonging to the terminal type C, these terminals 6 to 8 all determine the transmission destination of the terminal type B based on the priorities of the terminals 2 to 4.

  In the DDS standard or the DDS specification, when the terminals 1 to 8 participate as a publisher or a subscriber in a domain for registering a topic, these terminals 1 to 8 are information about other terminals connected to the domain. Can be obtained. The participating terminals 1 to 8 obtain these terminal information via the control information transmission / reception unit 11 of each terminal belonging to the terminal types A to C. Each of the terminals 5 to 8 acquires the respective priorities of the terminals 2 to 4 via the control information transmission / reception unit 11. At that time, the terminals 5 to 8 store the obtained priority between the terminals belonging to the terminal type B in the priority information table 18 and store the terminal address in the terminal information table 17.

  Each of the terminals 5 to 8 generates information to be transmitted to the terminal 1 using the information generation unit 16. These terminals 5 to 8 transmit data to any one of the terminal types B to be relayed through the information transmission unit 14. At this time, each of the terminals 5 to 8 refers to the priority information table 18, and when the priority of any one of the terminals 2, 3 and 4 is already set, the terminal information table of FIG. 7 to the terminal address of any one of terminals 2, 3 and 4, the destination determination process of FIG. 6 is performed.

  FIG. 6 is a flowchart for explaining a processing method for determining a transmission destination in the terminal 5 according to the present embodiment. In step A1, the terminal 5 selects a record having a transmittable terminal bit “1” among all the records in the priority information table 18, and selects the terminal name having the highest priority among the selected records. The destination determination process is executed for the terminal that has it. When the terminal 5 first obtains information on any of the terminals 2 to 4 that insist on priority, “1” (transmittable) is assigned to this transmittable terminal bit.

  For example, “1” is written in the transmittable terminal bit immediately after the terminal 5 is first wirelessly connected to one of the terminals 2 to 4. The terminal 5 is a terminal for all records in the priority information table 18 with respect to a record in which the transmittable terminal bit is “0” and a record in which the transmittable terminal bit is “1” and the priority is not the highest value. Is not performed for the destination. Here, the terminal 5 may determine the wireless connection state by using a HELLO message that the terminal 5 periodically sends to the terminals 2 to 4 of the terminal type B. The timing of writing “1” in the transmittable terminal bit may be changed according to the routing algorithm.

  When the transmission destination determination process is started (step A1), the terminal 5 reads the transmittable terminal bit from the priority information table 18, and has the highest priority among the relay terminals 2 to 4 whose transmittable terminal bit is “1”. A terminal with a high degree is selected (step A2). The terminal 5 transmits a packet to any one of the selected terminals 2 to 4 (step A3). The terminal 5 determines whether the transmission to the destination terminal that performed the transmission has succeeded or failed by monitoring whether or not a response has been received from the destination terminal that has transmitted the selected packet. (Step A4).

  When the terminal 5 receives the response from the previous terminal that performed the transmission in step A4 and determines that the transmission is successful, the terminal 5 passes through the route labeled “successful transmission” from the information transmitting unit 14, Data is transmitted to any of the information aggregating units 10 of the destination terminal that performed the transmission (step A5).

  If it is determined in step A4 that the transmission has failed, the terminal 5 passes through the route labeled “transmission failure”, and the terminal 5 sets the transmittable terminal bit in the priority information table 18 to “0” (cannot transmit). Then (step A6), the packet is transmitted again (step A7). The terminal 5 determines the success or failure of the transmission to the destination terminal that performed the transmission by monitoring the response from the destination terminal that performed the transmission (step A8).

  If the terminal 5 determines that the communication is successful in step A8, the terminal 5 passes through the route labeled “successful transmission”, sets the terminal bit capable of transmission to “1” (step A9), and is selected. Data is transmitted to any terminal of terminal type B (step A5). Thereby, transmission ends (step A10).

  In step A8, if the terminal 5 again determines that transmission has failed, the terminal 5 again refers to the priority information table 18 through the route labeled “transmission failure” and the transmittable terminal bit is “1”. "And the terminal with the highest priority is selected from the terminals 2 to 4 (step A2), and thereafter the same processing is performed.

  Here, the number of times the terminal 5 transmits the packet is not limited to one time. The terminal 5 may be provided with a threshold for the number of times, and if the packet is transmitted a number of times equal to or greater than a certain threshold among the plurality of times the packet is transmitted, it can be determined that the transmission is successful. Then, by repeating the above steps until the terminal 5 transmits to any terminal of terminal type B, the data can be transmitted to the most suitable one of the terminals 2 to 4. Become.

  Therefore, even if the terminal 5 needs to send data only once, as well as the process to retransmit the data, if the transmission fails as in the process of step A8, the transmittable terminal bit is set to “0”. The processing of step A2 and step A3 can be performed on the terminal belonging to the terminal type B having the next priority. If the transmission is successful in step A8, the terminal 5 determines that the transmission is still possible, updates the transmittable terminal bit of “0” to “1”, transmits the data, and the transmission fails. In this case, this bit is updated to “0”.

  The transmission destination determination processing method performed by the terminals 6, 7, and 8 belonging to the terminal type C is the same as the transmission destination determination processing method of the terminal 5.

  Thus, each terminal 5-8 performs the process which connects to each terminal 2-4, and reads the priority of these terminals 2-4 from the terminal priority information table 15 of the terminals 2-4 in the process of connecting. Then, the priority information table 18 is completed. The terminals 5 to 8 belonging to the terminal type C send data to the terminal having the highest priority among the terminals 2 to 4 belonging to the terminal type B, and do nothing to the other terminals. The data of the information generator 16 is sent only to the terminal type B terminal with the highest priority. Thereby, according to the communication system according to the present embodiment, data is selectively transmitted to any one of the terminals 2 to 4 connected to the terminals 5 to 8. That is, an automatic setting mechanism that can automatically set the communication destination is provided.

  Conventionally, in a communication system using DDS, a function for transmitting information by designating a specific destination and designating a destination of one terminal is lacking, but according to the communication system according to the present embodiment, This function can be supplemented, and the actual data transmission destination can be narrowed down to one place.

  In the communication method according to the present embodiment, any one of the terminals 5, 6, 7 or 8 as a transmission source terminal belonging to the terminal type C is assigned a priority that is ordered between the terminals 2 to 4, respectively. Is stored in the storage device of this terminal. Then, any one of the terminals 5, 6, 7 or 8 selects any one of the terminals 2 to 4 based on the priority, and transmits information to the selected terminal. Any one of the selected terminals 2 to 4 transmits this information to the terminal 1.

  Therefore, according to the communication method according to the present embodiment, information is accumulated in the information accumulation unit 10 of the terminal type A, and information having no duplicate content in the terminal type A is collected. For this reason, the terminal type A does not need to perform a process of deleting the duplicate information from the duplicate information required when the collected information is received. In addition, since duplicate information is not transmitted, information such as unnecessary samples is not transmitted, and the communication band to be used can be saved.

  According to the computer program according to the present embodiment, the middleware installed in each terminal has added a function of directly specifying a destination relay terminal, so that only one place among a plurality of relay terminals is provided. You will be able to send samples on the same topic. Therefore, in a communication system provided with a plurality of publisher terminals each capable of transmitting samples on the same topic, the publisher terminals jointly send the same sample to the subscriber terminals presenting the same topic. Such unnecessary data transfer can be eliminated. By installing this computer program in the terminal, the function of sending data to the intended subscriber terminal from one place among a plurality of relay terminals by exchanging data between middleware is added to the terminal Will be able to.

  As described above, according to the communication system, the transmission terminal, the relay terminal, the communication method, and the computer program according to the present embodiment, the subscription-side terminal is provided with a mechanism for setting the priority separately from the normal information transmission / reception mechanism. The publisher terminal obtains the priority of each subscriber terminal, selects the optimum subscriber terminal from these subscriber terminals according to the magnitude of the obtained priority, and selects the selected subscriber terminal. It becomes possible to transmit information. Since information is relayed from the selected subscriber terminal to the destination terminal, in this communication system, it is possible to eliminate the occurrence of duplicate data in the destination terminal and to reduce the compression of the communication band. Become.

  Note that 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. In the above embodiment, the communication system is wireless communication, but the communication system according to the present embodiment is also applicable to wired communication. Since the wireless communication system performs narrow band communication, the data transmission bandwidth in the communication system using the wired network is larger than the data transmission bandwidth in the communication system using the wireless network. Accordingly, even in a wired communication system in which a plurality of terminals communicate with each other via a wired network in which a plurality of terminals are connected by wired lines, the same effects as those obtained in the above embodiment can be obtained.

  In addition, the communication system according to the present embodiment can be managed by assigning different domain names to the same topic and permitting or not permitting access to the same topic by the domain name. For example, the domains that can be accessed by the terminals 5 to 8 are limited so as to be limited to the domains of the terminal type C and the terminal type B. The terminals 2 to 4 belong to the domain A and the domain B, and each terminal 2 to 4 belonging to the terminal type B converts the destination domain of the packet from the terminals 5 to 8 into the domains A and B, and then the data Can be transmitted to the domain A side. The communication system according to the present embodiment may perform packet transfer control using this domain, and in this way, exchange of information is permitted separately from the communicable range and the communication distance between terminals. Data can be relayed between existing domains.

  In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment.

It is a figure which shows the example of arrangement | positioning in the communication area of the terminal in the communication system which concerns on one Embodiment of this invention. It is a block diagram of several terminals including the transmission terminal and relay terminal which concern on one Embodiment of this invention. It is a figure which shows an example of the record memorize | stored in the terminal priority information table of the relay terminal which concerns on one Embodiment of this invention. It is a figure which shows an example of the terminal information table of the transmission terminal which concerns on one Embodiment of this invention. It is a figure which shows an example of the record memorize | stored in the priority information table of the transmission terminal which concerns on one Embodiment of this invention. It is a flowchart for demonstrating the processing method which determines the transmission destination in the transmission terminal which concerns on one Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Reception terminal, 2, 3, 4 ... Relay terminal, 5, 6, 7, 8 ... Transmission terminal, 9 ... Information reception process part, 10 ... Information accumulation part, 11 ... Control information transmission / reception, 12 ... QoS information storage part , 13 ... accumulating unit, 14 ... information transmitting unit, 15 ... terminal priority information table (first table), 16 ... information generating unit, 17 ... terminal information table (storage unit), 18 ... priority terminal table (first) 2 table).

Claims (5)

A transmitting terminal for transmitting information based on DDS (Data Distribution Service) and generating a topic on this information;
A receiving terminal that receives information corresponding to the topic;
A plurality of relay terminals that are hierarchically connected to the transmitting terminal and the receiving terminal and relay information from the transmitting terminal to the receiving terminal,
Each relay terminal
A first table storing one priority among a plurality of priorities ordered among the plurality of relay terminals;
A first transmission / reception unit that transmits / receives control information necessary for execution of a communication procedure defined by the DDS between the transmission terminal and the reception terminal;
The transmitting terminal is
A second transmission / reception unit for transmitting / receiving control information necessary for execution of the communication procedure to / from each relay terminal;
A storage unit for storing address information of each relay terminal acquired via the first transmission / reception unit and the second transmission / reception unit;
A second table that stores the priority of each relay terminal read from each first table of each relay terminal via the first transmission / reception unit and the second transmission / reception unit;
The transmitting terminal selects any one relay terminal based on each priority of the second table, transmits information to the selected relay terminal using the address information, and the selected relay terminal A communication system characterized by transmitting this information to a receiving terminal. An information generator for generating information;
A transmission / reception unit for transmitting and receiving information, a topic about this information, and control information necessary for execution of a communication procedure defined by the DDS, with a plurality of relay terminals forming a network together with the transmission terminal;
A storage unit for storing address information of these relay terminals received by the transmission / reception unit;
A table for storing priorities ordered among these relay terminals received from each of the plurality of relay terminals via the transceiver;
A control unit that selects any one relay terminal based on each priority and instructs the transmission / reception unit to transmit information to the selected relay terminal using the address information;
A transmission terminal used for a communication system comprising: Information transmitted from a transmission terminal that forms a network together with the relay terminal, a topic about this information, and control information necessary for execution of a communication procedure defined by the DDS, are transmitted to this transmission terminal and a reception terminal that forms this network. A transmission / reception unit for transmitting and receiving each
Stores one priority among a plurality of priorities ordered in advance among all the relay terminals received from the relay terminal and each of the other relay terminals forming the network together with the relay terminal Table,
A relay terminal used in a communication system comprising: Transmitting terminals that transmit information based on the DDS and generate a topic for this information are connected in a hierarchical manner to the transmitting terminal and a receiving terminal that receives information corresponding to the topic, respectively. Obtaining a priority from among a plurality of relay terminals that relay information to the receiving terminal, respectively, among a plurality of priorities ordered among these relay terminals;
The transmitting terminal selecting any one relay terminal from the plurality of relay terminals based on the priority;
The transmitting terminal transmits information to the selected relay terminal;
The selected relay terminal transmits this information to the receiving terminal;
A communication method in a communication system, comprising: Transmitting terminals that transmit information based on the DDS and generate a topic for this information are connected in a hierarchical manner to the transmitting terminal and a receiving terminal that receives information corresponding to the topic, respectively. Obtaining a priority from among a plurality of relay terminals that relay information to the receiving terminal, each of the priorities ordered among these relay terminals;
The transmitting terminal selecting any one relay terminal from the plurality of relay terminals based on the priority;
The transmitting terminal transmits information to the selected relay terminal;
The selected relay terminal transmits this information to the receiving terminal;
Is executed by a computer provided in each of the transmission terminal, the reception terminal, and the plurality of relay terminals.

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