JP4394537B2 - Data transmission method and terminal device in ad hoc network - Google Patents

Description

The present invention relates to a data transfer method and a terminal device in a multi-hop network in which a plurality of information processing terminals such as a workstation, a personal computer, a handheld computer, a mobile phone, and a small sensor are connected by wire or wireless. The present invention relates to a data transmission method and a terminal device suitable for transmission of large-capacity streaming data in an ad hoc network in which a plurality of information processing terminals are dynamically connected according to surrounding conditions.

  In recent years, small information processing terminals such as mobile phones, PDAs and car navigation systems have become widespread. Ad hoc networks are attracting attention as a communication network technology for connecting these information processing terminals as needed and operating them in cooperation with each other. An ad hoc network is a communication method that interconnects terminals without using a communication infrastructure such as a base station or a server serving as an access point to the network by relaying packets in a bucket relay format to multiple terminals. is there.

  Examples of applications suitable for an ad hoc network include a video monitoring system and a voice call system. FIG. 1 shows an example of a video surveillance system using an ad hoc network.

  The video monitoring system shown here includes a plurality of camera-equipped terminals 101 (101-1 to 101-9) and a monitor terminal 102 connected by a wireless line. The output video from the camera-equipped terminal 101-1 located around the monitoring range is transmitted to the monitor terminal 102 using the camera-equipped terminals 101-5 to 101-7 as relay terminals. Similarly, the output video from the camera-equipped terminal 101-2 is transmitted to the monitor terminal 102 using the camera-equipped terminals 101-8, 101-6, and 101-7 as relay terminals, and output from the camera-equipped terminal 101-3. The video is transmitted to the monitor terminal 102 using the camera-equipped terminals 101-9 and 101-7 as relay terminals, and the output video from the camera-equipped terminal 101-4 is transmitted to the monitor terminal 102, respectively. That is, the monitor terminal 102 is connected to a plurality of camera terminals via a wireless multi-hop network.

  The monitor terminal 102 can receive the video data transmitted from the camera-equipped terminal, and can display the images on the display 103 so that images of a plurality of sites can be listed, or can selectively display only the images of a specific site. . According to this system, the monitor terminal 102 is connected to the camera terminals 101-1 to 101-4 via the relay terminals 101-5 to 101-9 so that the monitor terminal 102 receives radio waves. Since it is possible to receive video from a terminal at a remote location that does not reach directly, it is possible to easily construct a video monitoring system simply by arranging a plurality of camera-equipped terminals in the monitoring target area.

  In the ad hoc network described above, the number of relay terminals (the number of hops) interposed between the data transmission source terminal (camera-equipped terminal in the above example) and the destination terminal (monitor terminal), radio noise generated in the relay section, etc. Accordingly, there is a problem that variations occur in the data transmission delay time and throughput. For example, the number of relay terminals through which the image data from the camera-equipped terminal 101-1 located at the position farthest from the monitor terminal 102 is larger than the image data from the camera-equipped terminal 101-4 at a relatively close position. Since the number is increased, the delay time is large and the throughput is also reduced. Therefore, when a list of videos from a plurality of sites is displayed on the display 103 of the monitor terminal 102, the video from the camera-attached terminal 101-1 is displayed with a time delay from the video of other sites, There is a high possibility that the display frame is lost due to a decrease in throughput. That is, when transmitting a large amount of data such as streaming data using an ad hoc network, QoS control for efficiently using a limited network bandwidth becomes an important issue.

  In order to solve this problem, for example, in Japanese Patent Laid-Open No. 2003-273788 (Patent Document 1), a transmission packet in a communication section having a large number of hops is divided into a plurality of packets and transmitted, or relay processing is performed with high priority. Propose to do. Further, as a transmission protocol capable of adjusting the quality of streaming data, there is RTP (Real-time Transport Protocol). RTP is described in RFC 1889 “RTP: A Transport Protocol for Real-Time Applications”, http://www.ietf.org/rfc/rfc1889.txt (page 3-5) (Non-patent Document 1). ing. In RTP, the delay time is detected based on the time stamp information and sequence number added to each transmission packet, and this is reported to the data transmission source server by RTCP (RTP Control Protocol), and the server responds to the communication state of the packet. The transmission delay can be reduced by adjusting the priority specification value of the transmission data.

JP2003-273788 (page 5-6, Fig. 1-2) “RTP: A Transport Protocol for Real-Time Applications”, RFC1889, http://www.ietf.org/rfc/rfc1889.txt (page 3-5)

  In a wireless ad hoc network, each relay terminal transmits data from the relay terminal itself as a transmission source in addition to the operation of transferring transmission data from other terminals to the destination terminal, or performs application processing unique to the terminal. There is a possibility to execute. In the network configuration shown in FIG. 1, for example, the relay terminal 101-6, in parallel with the operation of transferring the transmission data from the camera-equipped terminals 101-1 and 101-2 to another relay terminal 101-7, May execute data processing for recording video data captured by a camera or transmitting it to another terminal.

  Here, the relay terminal 101-6 tries to transmit the video data taken by the camera when the wireless communication band is consumed by the transmission of the transmission data generated in the terminals 101-1 and 101-2. However, there arises a problem that a necessary bandwidth cannot be secured. In addition, transfer processing of received data from other terminals consumes terminal hardware resources such as CPU processing capacity and memory capacity, and CPU processing and free memory necessary for executing applications for itself are insufficient. Problem occurs.

  The methods described in Patent Document 1 and Non-Patent Document 1 are for specifying the data transmission timing of the transmission terminal and changing the packet transfer order in the relay terminal in order to ensure the quality of the received data at the destination device. However, the resources required by the relay terminal itself cannot be secured at any time. Therefore, in a wireless ad hoc network, there is a problem that each relay terminal cannot be satisfactorily executed by processing from its own terminal simply by being used from another terminal, and for the transmitting terminal, the relay terminal performs its own terminal operation. When started, there was a problem that the data throughput of the relay section fluctuated.

An object of the present invention is to provide a data transmission method capable of effectively using terminal resources in a network system in which each terminal can be a transmission terminal, a reception terminal, and a relay terminal as in an ad hoc network.
Another object of the present invention is to reduce the amount of relay data according to the state of the relay terminal, particularly when transmitting a large amount of data such as video and voice in an ad hoc network in which a plurality of terminals are connected in a multi-hop manner. An object of the present invention is to provide a data transmission method capable of effectively using resources of a relay terminal by controlling.

  To achieve the above object, according to the present invention, in a data transmission method in a network system in which a plurality of terminals are connected in a multihop manner, at least one other terminal is used as a data relay terminal from the first terminal to the second terminal. A first step of transmitting data, a second step of transmitting a control message for controlling the transmission amount of relay data from the data relay terminal to the first terminal, and the first terminal according to the content of the control message, And a third step of changing a transmission mode of data addressed to the second terminal.

  In one embodiment of the present invention, the data relay terminal has a management table that defines the relationship between the data processing type, the required resource amount, and the transmission data suppression content, and the current free resource amount is the data processing to be executed. When the required resource amount indicated by the management table is less than the corresponding type, a control message generated according to the transmission data suppression content indicated by the management table is transmitted to the first terminal.

  In the present invention, the data relay terminal transmits the control message when, for example, a shortage occurs in resources required for data processing executed by the terminal. However, a control message indicating the state of the resource of the data relay terminal is periodically transmitted from the data relay terminal to the first terminal, and the first terminal transmits data addressed to the second terminal according to the content of the control message. The transmission mode may be changed. Further, a control message indicating the state of the resource of the data relay terminal is periodically transmitted from the data relay terminal to the second terminal, and the second terminal transmits the control message from the first terminal to the second terminal according to the content of the control message. The amount of transmission data addressed to two terminals may be controlled. In this case, the second terminal can control the amount of data passing through the data relay terminal, for example, by changing the data acquisition interval from the first terminal.

  According to the present invention, terminal resources in an ad hoc network are consumed for a relay service of transmission data from other terminals, and resources such as CPU capacity, memory capacity, and network bandwidth are used when executing data processing of the terminal itself. Can solve the inconvenience that a satisfactory operation cannot be executed due to a lack of In addition, for a terminal operating as a data transmission terminal or data reception terminal, a problem that the communication data transfer process suddenly slows because the relay terminal starts its own data processing without any prior notice during communication. There is an advantage that data communication suitable for the communication environment can be performed.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 2 shows a block diagram of an information processing terminal which is a component of the ad hoc network of the present invention. 2A is an information processing terminal 101-Tx that is a data transmission source, FIG. 2B is an information processing terminal 101-R that is a relay terminal, and FIG. 2C is information that is a data reception terminal. The configuration of the processing terminal 102 is shown. As these information processing terminals, for example, a workstation, a personal computer, a handheld computer, a mobile phone, a small sensor, or the like is applied. These information processing terminals (hereinafter simply referred to as terminals) are multi-hop connected via a wired channel, a wireless channel, or an ad hoc network in which these channels are mixed.

  The data transmission source terminal 101-Tx corresponds to one of the camera-equipped terminals 101-1 to 101-4 in the network system of FIG. 1, and the relay terminal 101-R is the relay terminal 101-5 of FIG. Corresponds to one of 101-9. Each of the terminals 101-Tx, 101-R, 102 includes a processor 110, an input device 111 such as a camera or a microphone, a display device 112 such as a display or LED, and a communication interface 113 for connecting to a network such as a wireless LAN. A program memory 114 and a data memory 115, and these elements are interconnected by a bus 116.

  The relay terminal 101-R functions as the data transmission source terminal 101-Tx depending on the situation. Further, the data transmission source terminal 101-Tx also functions as the relay terminal 101-R depending on the situation. Therefore, in actual application, each terminal is provided as having both functions of the data transmission source terminal 101-Tx and the relay terminal 101-R. Here, in order to facilitate understanding of the invention, 2A shows functions necessary for the data transmission source terminal 101-Tx, and FIG. 2B shows functions necessary for the relay terminal 101-R. However, the display device 112 is not an essential component for the transmission terminal 101-Tx and the relay terminal 101-R.

  In this embodiment, the data memory 115 of the relay terminal 101-R stores the relationship between the route information table 300 indicating the network route from the own terminal to a specific terminal, and the source and destination of the data packet in the relay service. The relay management table 310 shown, and the transmission suppression request condition table 320 indicating the issuance conditions of the transmission data suppression request message to be transmitted to the transmission terminal of the data in the relay service when the resource is insufficient are stored. In addition, the program memory 114 of the relay terminal 101-R includes a route management routine 200 for detecting a terminal group existing in the vicinity and updating the route information table 231, and an appropriate received packet according to the route information table 300. A data transfer routine 220 for transferring data to the terminal, a relay management routine 240 for updating the relay management table 232, and a data transmission routine 260 for transmitting input data from the input device 111 to another specific terminal are prepared. ing.

  The data memory 115 of the transmission terminal 101-Tx stores a route information table 300 and a transmission mode table 330 that is updated in response to a transmission data suppression request from the relay terminal. Further, a route management routine 200 and a data transmission routine 260 are prepared in the program memory 114 of the transmission terminal 101-Tx.

  A route information table 300 is stored in the data memory 115 of the receiving terminal 102, and a route management routine 200 and a data reception / display routine for outputting received data from other terminals to the display device 112 are stored in the program memory 114. 280 is prepared.

FIG. 3 shows an example of the relay management table 310.
In the relay management table 310, the source IP address 311 of the data packet to which the relay terminal 101-R is applying the relay service, the destination IP address 312 and the processing time (final service time) 313 of the last relay packet. A plurality of entries 31-1, 31-2,...

FIG. 4 shows an example of the transmission suppression request condition table 320.
The transmission suppression request condition table 320 includes a plurality of entries 32-1, 32-2, 32-3,... Prepared corresponding to the application type 321, each entry being an application program designated by the application type 321. Of the transmission data suppression request to be transmitted to the transmission source terminal of the data (packet) in the relay service when the resource amount 322 required at the time of execution and the resource specified by the resource amount 322 cannot be secured Is shown. The transmission data suppression request differs depending on the type of application to be executed. For example, if a resource shortage occurs during execution of an application that handles real-time information such as video distribution or audio distribution, the transmission data suppression request is transmitted to the transmission source of the relay packet. On the other hand, if there is a shortage of resources during execution of an application that handles text data, requesting to cancel data transmission or reducing the amount of data to be sent, the content of the relay packet sender is requested to lower the priority of the transmission data. ing.

FIG. 5 shows an embodiment of the transmission mode table 330.
The transmission mode table 330 corresponds to the application type 331 executed in the data transmission terminal 101-Tx, and the content 332 of the transmission data suppression request received from the relay terminal, and is executed in the data transmission terminal for transmission data suppression. It consists of a plurality of entries 33-1, 33-2,...

  The route information table 300 shows the relationship between the destination address of the received packet and the next hop destination, and the contents are managed by the route management routine 200. The route management routine 200 is configured by ad hoc routing software that implements a protocol such as AODV (Ad hoc On-Demand Distance Vector) and OLSR (Optimized Link State Routing). The data transfer routine 220 is configured by an IP routing function of the OS, and the data reception / display routine 280 is configured by client software such as Microsoft Windows Media Player.

  FIG. 6 shows an overall operation sequence of the ad hoc network system according to the present invention. Here, the terminal device D and the terminal device E are transmitting terminals and transmit data to the receiving terminal A via the relay terminal C (S1). In this state, when a data transmission request is generated in the relay terminal C (S2), and when it is necessary to start data transmission from the relay terminal C to the receiving terminal B, in the present invention, the data transmission routine of the relay terminal C is performed. 260 checks the amount of free resources, and if it finds that there is not enough free resources necessary for data transmission, the data transmission terminals in the relay service (here, transmission terminals D and E) In response to this, a transmission data suppression request message is issued (S3).

  When receiving the transmission data suppression request message from the relay terminal C, the transmission terminals D and E reduce the amount of transmission data addressed to the reception terminal A according to the request content indicated by the reception message (S4). The relay terminal C starts data transmission in a state where resources necessary for data transmission addressed to the reception terminal B can be secured by reducing the amount of transmission data from the transmission terminals D and E (S5). Note that data transmission addressed to the receiving terminal B from the relay terminal C may be started after receiving response messages from the transmitting terminals D and E in response to the transmission data suppression request message.

FIG. 7 is a flowchart showing an embodiment of the relay management routine 240 executed by the relay terminal 101-R (relay terminal C in FIG. 6).
In the relay management routine 240, a timer for informing the elapse of the fixed time T0 is started (step 241). As will be described later, this timer is used to delete unnecessary entries that have passed a predetermined time from the last service time among the registered entries in the relay management table 310. Next, in the relay management routine 240, it is determined whether or not there is a program end instruction by a user operation (242). If the end instruction is received, the routine is ended. If there is no end instruction, it is checked whether or not the timer has timed out (step 243), and if it has not timed out, a packet to be relayed is captured (capturing) (244). If there is no relay packet, the process returns to step 242 to repeat the above-described processing.

  When a packet to be relayed is captured, the captured packet is relayed and the source IP address and the destination IP address are extracted from the IP header (245). Thereafter, the relay management table 310 is referenced to check whether there is an entry in which the relationship between the source IP address 311 and the destination IP address 312 corresponds to the combination of the source IP address and the destination IP address of the relay packet (246). . If the entry corresponding to the IP address combination has been registered in the relay management table 310, the last service time 313 of the entry is updated to the current time (248), and the process returns to step 242, and if not registered, After adding a new entry having the IP address combination to the relay management table (247), step 248 is executed.

  If the timer has timed out in step 243, the last service time 313 of the relay management table 310 is checked, and an entry for which a predetermined time T1 (T1> T0) has passed since the last service time 313 is found (249). If there is no entry for which the predetermined time T1 has elapsed since the last service time 313, the process returns to step 401, and for the entry for which the predetermined time T1 has elapsed, it is determined that transmission of the packet to be relayed is complete, and the relay management table After deletion (250) from 310, the process returns to step 401. Packet capturing is realized by software such as Ethereal.

FIG. 8 is a flowchart illustrating an example of a data transmission routine 220 executed by the transmission terminal 101-Tx (terminals D and E in FIG. 6) and the relay terminal 101-R (terminal C in FIG. 6).
The data transmission routine 220 waits for a data transmission request generated in response to a user operation or the like (step 261). When the data transmission request is received, the data transmission routine 220 automatically determines whether there is a registered entry in the relay management table 310 shown in FIG. It is determined whether or not the terminal is operating as a relay terminal, that is, whether or not the data relay service is being executed (262). In the case of the transmission terminal 101-Tx in which the valid entry is not registered in the relay management table 310 (the relay management table 310 itself is omitted in FIG. 2A), the data is immediately updated regardless of the amount of free resources. Transmission is started (267).

  In the case of the relay terminal 101-R, first, the current free resource amount in the own terminal is grasped (263). In the case of Linux, for example, in the case of Linux, the top module can grasp the CPU usage rate and the memory consumption, and the iftop module can grasp the bandwidth usage for each communication interface. Next, an entry corresponding to the application type that is the data transmission request source is searched from the transmission suppression request condition table 233 shown in FIG. 4, and the current free resource amount is the required resource amount indicated by the search entry. It is determined whether or not 322 is satisfied (264). If the amount of free resources is sufficient, data transmission is started immediately (267). If the free resource amount is insufficient, the transmission terminal IP address 311 of the data currently being relayed is acquired from the relay management table 310 (265), and the request content 323 indicated by the entry retrieved from the transmission suppression request condition table 233 is obtained. Accordingly, a transmission data suppression request message is generated and transmitted to each transmission terminal (266), and then data transmission is started (267). However, as described above, data transmission may be started after reception of a response message from each transmission terminal.

  For example, as shown in FIG. 9, the transmission data suppression request message includes an IP header 401, a TCP / UDP header 402, a message type 403, a transmission time 404 of the message, and a request content 405. A code indicating that this message is a transmission data suppression request is set in the message type 403, and code information indicating the request content 323 retrieved from the transmission suppression request condition table 233 is set in the request content 405. However, the request content 323 may be set in the message type 403, and the specific data amount to be reduced may be set in the request content 405 of the transmission data suppression request message.

  Returning to FIG. 8, in the data transmission routine 220, after data transmission is started (267), it is determined whether or not there is an instruction to end data transmission (268). The data transmission end instruction is generated, for example, when the application program is ended by a user operation or the like. If there is an end instruction, as in step 262, it is determined whether or not the own terminal is operating as a relay terminal (271). If not operating as a relay terminal, this routine is ended. When the own terminal is operating as a relay terminal, the transmission terminal IP address 311 of data currently being relayed is acquired from the relay management table 310 (272), and a transmission data suppression release message is transmitted to each transmission terminal ( 273), this routine is terminated.

  If there is no termination instruction, it is determined whether or not a transmission data suppression control message (transmission data suppression request message or transmission data suppression cancellation message) is received from another relay terminal (269). If no transmission data suppression control message has been received, the process returns to step 268. If the transmission data suppression request message has been received, the transmission mode table 330 changes the application type that is the source of the transmission data and the request contents indicated by the received transmission data suppression request message. When the transmission operation mode 333 is specified, the transmission data is suppressed according to the transmission operation mode, and the transmission data suppression release message is received, the transmission data suppression is canceled and the original transmission operation mode is restored (270).

  In the transmission mode table 330 shown in FIG. 5, for example, the transmission suppression request 332 of the entries 33-2 and 33-3: “Reduction of less than 20% of transmission data amount”, “Reduction of 20% or more of transmission data amount” As shown, the transmission operation change mode 333 to be taken by the transmission terminal is defined on the assumption that a specific transmission data reduction target value is indicated in the transmission data suppression request message received during execution of the video distribution application. Yes. That is, for example, when the transmission data suppression request message specifies “reduction of transmission data amount of 0.3 Mbps” and the video distribution application being executed at the transmission terminal is transmitting 3 Mbps data, the transmission data reduction amount As a result, the data compression method is changed to “Code A” in accordance with the transmission operation change mode 333 of the entry 33-2.

  Here, in the relay terminal that is the transmission source of the transmission data suppression request message, several methods can be considered as a method for determining the amount of transmission data reduction that should be requested to the data transmission terminal. For example, since the CPU usage is approximately proportional to the number of relay packets, if the lack of resources is the CPU processing capacity, in order to secure the CPU processing capacity required by the terminal itself, the amount of relay packets It can be judged whether or not it should be reduced to some extent. Therefore, the reduction amount of transmission data to be requested from the data transmission terminal can be calculated from the packet amount to be reduced.

  When the relay data transmission source is a plurality of terminals, the transmission data reduction amount may be shared by the plurality of transmission terminals. For example, when there are three terminals serving as relay data transmission sources and the network bandwidth to be reduced is 3 Mbps, it is only necessary to request each transmission terminal to reduce transmission data by 1 Mbps. The reduction of transmission data may be unequally allocated to a plurality of transmission terminals at different ratios. The allocation of the reduction amount may be proportional to the current transmission data amount, and as a result, the allocation may be determined by negotiation with the transmission terminal so that necessary resources on the relay terminal side can be secured.

As a transmission operation mode for transmission data suppression, in addition to the above-described reduction in transmission data amount, for example, as indicated by entry 33-1 of transmission mode table 330, a route for changing a relay terminal to be routed to another terminal As shown in the entry 33-5, there is a change, a change in the IP packet Tos field value for lowering the packet transfer priority in the relay terminal, and the like.
In the above embodiment, when the terminal in the data relay service starts the data transmission of its own terminal, when there are insufficient free resources to be secured, for each terminal serving as the relay data transmission source, Although an example of requesting transmission data suppression has been described, issuing a transmission data suppression request is not necessarily accompanied by data transmission by an application executed on a relay terminal.

  In order to achieve the object of the present invention, for example, each relay terminal periodically transmits a control message indicating the resource state of the terminal itself to each terminal that is a transmission source of the relay data. The amount of transmission data may be voluntarily controlled according to the state of the relay terminal indicated by the control message. In addition, each relay terminal periodically transmits a control message indicating the resource state of the terminal itself to the receiving terminal that is the destination of the relay data, and the receiving terminal responds according to the state of the relay terminal indicated by the control message, The amount of data acquired from the data transmission terminal may be controlled. For example, when the receiving terminal acquires data by polling the transmitting terminal, the resource consumption of the relay terminal can be adjusted by dynamically changing the polling interval.

  In the embodiment, the example in which the data transmission terminal is recognized by the relay packet capturing in the relay management routine 240 has been described. For example, on an ad hoc network employing a DSR (Dynamic Source Routing) protocol, route information is included in a Route Request message and a Route Reply message. Therefore, the relay data transmission source terminal may be recognized from these messages.

The figure which shows an example of the ad hoc network to which this invention is applied. The block block diagram of the information processing terminal used as the component of the ad hoc network of this invention. The figure which shows one Example of the relay management table 310. FIG. The figure which shows one Example of the transmission suppression request | requirement condition table 320. FIG. The figure which shows one Example of the transmission mode table. The figure which shows the whole operation | movement sequence of the ad hoc network system of this invention. 5 is a flowchart illustrating one embodiment of a relay management routine 240. 9 is a flowchart showing one embodiment of a data transmission routine 260. The figure which shows the format of a transmission data suppression request message.

Explanation of symbols

101: Terminal with camera, 102: Monitor terminal, 103: Display,
110: processor, 111: input device, 112: display device,
113: Communication interface, 114: Program memory, 115: Data memory,
116: Bus, 200: Path management routine, 220: Data transfer routine,
240: Relay management routine, 260: Data transmission routine,
280: Data reception / display routine, 300: Path information table,
310: Relay management table, 320: Transmission suppression request condition table,
330: Transmission mode table.

Claims (7)

In a data transmission method in a network system in which a plurality of terminals are multi-hop connected,
A first step of transmitting data from the first terminal to the second terminal using at least one other terminal as a data relay terminal;
In the above relay terminal operating in the data relay mode, when a resource the application program of its own terminal needs becomes insufficient state, in the first terminal from the data relay terminal, transmitting the data relayed by the relay terminal A second step of sending a control message for requesting suppression ;
The first terminal comprises a third step of changing the transmission mode of data addressed to the second terminal according to the request content indicated by the control message ;
The data transmission method according to claim 1, wherein a request content of the control message differs depending on a type of the application program . The data relay terminal stores a required resource amount in advance for each specific type of application program executed on the terminal, and the amount of free resources is less than the previously stored required resource amount due to data relay . 2. The data transmission method according to claim 1, wherein the control message is transmitted. The data relay terminal has a management table which defines the relationship between the type and required resource amount of the application program and the transmission data suppression request content, when the data transmission request is generated at the terminal itself, the current amount of free resources when less than the amount of resources that have been designated category and then the corresponding resource required by the management table of the application program that a generation source of the data transmission request, in accordance with the transmission data suppression request content which the management table is shown The data transmission method according to claim 1, wherein the generated control message is transmitted to the first terminal. In a data transmission method in a network system in which a plurality of terminals are multi-hop connected,
A first step of transmitting data from the first terminal to the second terminal using at least the third terminal as a data relay terminal;
A second step of transmitting data from the fourth terminal to the second terminal or another terminal using at least the third terminal as a data relay terminal;
In the third terminal operating in the data relay mode, the amount of relay data is suppressed from the third terminal to the first and fourth terminals when the resource required by the application program of the terminal becomes insufficient. A third step of transmitting a control message for
The first and fourth terminals comprise a fourth step of changing the respective data transmission modes according to the content of the control message,
A data transmission method characterized in that the content of the control message varies depending on the type of the application program . The third terminal has a management table that defines the relationship between the type of application program, the required resource amount, and the transmission data suppression request content, and when a data transmission request is generated in the own terminal, the current free resource amount is Control generated according to the content of the transmission data suppression request indicated by the management table when the required resource amount corresponding to the type of application program that is the source of the data transmission request is less than the resource amount specified in the management table 5. The data transmission method according to claim 4, wherein a message is transmitted to the first and fourth terminals. A terminal device for an ad hoc network,
A first management table storing a relationship between a source address and a destination address of a data packet relayed in the data relay mode;
A second management table that defines the relationship between the type of application program, the required resource amount, and the content of transmission data suppression request;
When a data transmission request is generated in the own terminal, it is determined by the first management table whether or not it is operating in the data relay mode. When operating in the data relay mode, the current free resource amount is It is determined whether or not the resource amount specified in the second management table is satisfied as the required resource amount corresponding to the type of application program that is the source of the transmission request. After generating a transmission data suppression request message according to the transmission data suppression request content indicated by the second management table, and transmitting the transmission data suppression request message to the source address stored in the first management table, A terminal device comprising: data transmission means for transmitting data requested by a data transmission request. The terminal device according to claim 6,
A third management table that defines the relationship between the type of application program, the transmission suppression request condition, and the transmission operation mode;
When the transmission data suppression request message is received from another terminal device, the data transmission means includes the type of the application program that is the source of transmission data in its own terminal, and the request content indicated by the transmission data suppression request message And a transmission operation mode after the change is specified from the third management table, and transmission data is suppressed according to the transmission operation mode.

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