JP2020065222A - Communication system, relay device, and communication method - Google Patents

Abstract

To suppress a traffic number by proxy communication.SOLUTION: A transmission device 2 transmits object data T to a reception device 4, and re-transmits the object data T to the reception device 4 when not receiving notification indicating the reception device 4 has received the object data T within a predetermined time after transmitting the object data to the reception device 4. When detecting no transmission of reception notification indicating the reception device 4 has received the object data T in response to the transmission device 2 having transmitted the object data T to the reception device 4, a relay device 3 performs proxy communication of the object data T to the reception device 4 and transmits notification indicating the reception device 4 has received the object data T to the transmission device 2. When detecting retransmission of the object data T by the transmission device 2, the relay device 3 further transmits notification indicating the reception device 4 has received the object data T to the transmission device 2.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a communication system including a plurality of devices, a relay device used in the communication system, and a communication method.

  AODV (Ad hoc On-Demand Distance Vector), DSR (Dynamic Source Routing) and the like are known as communication protocols between a plurality of devices in an ad hoc network that uses radio. Further, in an ad hoc network that uses wireless communication, when a transmitting device cannot directly communicate with a receiving device, another device that belongs to the network becomes a relay device, and instead of the transmitting device, a proxy communication method for transmitting to the receiving device. (See Patent Document 1).

  In Patent Document 1, the relay device intercepts the direct data addressed to the receiving device from the transmitting device, and when the reception notification for the direct data cannot be received thereafter, the relay device substitutes the direct data for the receiving device instead of the transmitting device. connect. When the relay device receives the reception notification from the reception device, the relay device notifies the transmission device of the completion notification of the proxy communication. As a result, it becomes possible to quickly transmit data from the transmitting device to the receiving device.

JP, 2014-225859, A

  In Patent Document 1, when the transmission device cannot receive the notice of completion of proxy communication from the relay device, the transmission device retransmits the data directly to the reception device, even though the data is directly received by the reception device. . When the transmitting device directly retransmits the data, the relay communication by the relay device is performed again, and the number of traffics by the proxy communication in the communication system may increase.

  Therefore, an object of the present invention is to provide a communication system, a relay device, and a communication method that suppress the number of traffics by proxy communication.

  In order to solve the above problems, a first feature of the present invention relates to a communication system including a plurality of devices. A communication system according to a first aspect of the present invention includes a transmitter that transmits target data, a receiver that is a destination of the target data, and a relay device that can communicate with the transmitter. If the transmitting device transmits the target data to the receiving device, transmits the target data to the receiving device, and does not receive the notification indicating that the receiving device has received the target data within a predetermined time, Is transmitted to the receiving device. When the relay device detects that the transmission device has transmitted the target data to the reception device but the reception notification indicating that the reception device has received the target data is not transmitted, the relay device sets the target data to the relay data. When the receiving device receives the notification indicating that the target device stored in the relay data and the overheard processing unit that stores the target data stored in the relay data are proxy-transmitted to the receiving device, and the receiving device receives the target data, the receiving device notifies the transmitting device. When a relay unit that sends a notification indicating that the target data has been received and a retransmission of the target data by the sending device are detected, a reception re-transmission that sends a notification that the receiving device has received the target data to the sending device. A notification unit is provided.

  A second feature of the present invention relates to a relay device used in a communication system including a plurality of devices. A communication system in which the relay device according to the second aspect of the present invention is used includes a transmitter that transmits target data, a receiver that is a destination of the target data, and a relay device that can communicate with the transmitter. When the relay device detects that the transmission device has transmitted the target data to the reception device but the reception notification indicating that the reception device has received the target data is not transmitted, the relay device sets the target data to the relay data. When the receiving device receives the notification indicating that the target device stored in the relay data and the overheard processing unit that stores the target data stored in the relay data are proxy-transmitted to the receiving device, and the receiving device receives the target data, the receiving device notifies the transmitting device. When a relay unit that sends a notification indicating that the target data has been received and a retransmission of the target data by the sending device are detected, a reception re-transmission that sends a notification that the receiving device has received the target data to the sending device. A notification unit is provided.

  When the relay unit transmits a notification indicating that the receiving device has received the target data to the transmitting device and a predetermined time elapses, and then the retransmission of the target data by the transmitting device is not detected, the reception re-notifying unit determines the receiving device. Discards the notification indicating that the target data has been received, and when retransmission of the target data by the transmission device is detected by the time the predetermined time has elapsed, the reception re-notification unit causes the transmission device to notify the target device of the target data. The notification indicating the reception may be retransmitted.

  The relay device is further capable of communicating with the receiving device, and the notification indicating that the receiving device received by the relay unit has received the target data is a reception notification indicating that the receiving device has received the target data by proxy communication. The notification indicating that the receiving device, which is transmitted by the reception re-notifying unit, has received the target data may be a proxy communication completion notification.

  The communication system further includes a relay device and another relay device capable of communicating with the reception device, and the notification indicating that the reception device received by the relay unit has received the target data indicates that the relay device has performed the proxy communication of the target data. On the other hand, when another relay device detects that the reception notification indicating that the receiving device has received the target data is not transmitted, the other relay device further communicates the target data to the receiving device by proxy communication. When a reception notification indicating that the target data has been received by communication is received, it is a notification of completion of proxy communication sent by another relay device, and the relay unit sends a notification of completion of proxy communication by the other relay device. On the other hand, when the sending device detects that the reception notification indicating that the completion notification of the proxy communication has been received is not sent, it substitutes the completion notification of the proxy communication sent by another relay device. Communication, notification receiver receiving re-notification unit sends indicate that it has received the target data relay unit may be a notification of completion of the proxy communication to the proxy communication.

  A third aspect of the present invention relates to a communication method used in a communication system including a plurality of devices. A communication system using the communication method according to the third aspect of the present invention includes a transmitter that transmits target data, a receiver that is a destination of the target data, and a relay device that can communicate with the transmitter. The communication method includes a step in which the transmission device transmits the target data to the reception device, and a relay device receives the target data in response to the transmission device transmitting the target data to the reception device. When it is detected that the reception notification indicating that the data has been transmitted is not transmitted, the step of storing the target data in the relay data and the relay device performing the proxy communication of the target data stored in the relay data to the receiving device and receiving When the device receives the notification indicating that the target data has been received, a step of transmitting a notification indicating that the receiving device has received the target data to the transmitting device, and the transmitting device sends the target data to the receiving device. If the receiver does not receive the notification indicating that the target data has been received within the predetermined time, the step of retransmitting the target data to the receiver, and the relay device When retransmission of the target data by the transmitting device is detected, the transmitting device comprises the step of transmitting a notification indicating that the receiving apparatus has received the target data.

  According to the present invention, it is possible to provide a communication system, a relay device, and a communication method that suppress the number of traffic due to proxy communication.

It is a system configuration diagram of a communication system according to an embodiment of the present invention. It is an example of a data structure transmitted by the relay device according to the embodiment of the present invention. It is a sequence diagram explaining the process of the communication method which concerns on embodiment of this invention. It is a figure explaining the hardware constitutions and functional block of the transmitter concerning an embodiment of the invention. 5 is a flowchart illustrating processing of a transmission unit according to the embodiment of the present invention. It is a figure explaining the hardware constitutions and functional block of the relay device concerning an embodiment of the invention. It is a figure explaining the data structure of relay data which concerns on embodiment of this invention, and an example of data. It is a figure explaining an example of a data structure and data of reception re-notification accumulation data concerning an embodiment of the invention. It is a flow chart explaining processing of an over hear processing part concerning an embodiment of the invention. It is a flow chart explaining processing of a relay part concerning an embodiment of the invention. 6 is a flowchart illustrating a process in which the relay unit according to the embodiment of the present invention retransmits target data. 7 is a flowchart illustrating a process in which the relay unit according to the embodiment of the present invention retransmits a notification of completion of proxy communication. 7 is a flowchart illustrating a process of a reception re-notification unit according to the embodiment of the present invention. It is a system block diagram of the communication system which concerns on a modification. It is a sequence diagram explaining the process of the communication method which concerns on a modification.

  Next, an embodiment of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar reference numerals are given to the same or similar parts.

(Communications system)
A communication system 5 according to an embodiment of the present invention will be described with reference to FIG. The communication system 5 includes a plurality of communication devices 1, and the communication devices are connected in a mesh to form a wireless mesh network.

  The communication system 5 shown in FIG. 1 includes a first communication device 1a, a second communication device 1b, a third communication device 1c, and a fourth communication device 1d. In the embodiment of the present invention, the first communication device 1a, the second communication device 1b, the third communication device 1c, and the fourth communication device 1d may be simply referred to as the communication device 1 unless otherwise distinguished. . Although FIG. 1 includes four communication devices, the number of communication devices is not limited to this.

  In the embodiment of the present invention, each communication device 1 functions as a transmission device 2, a reception device 4, or a relay device 3 depending on the role in each communication. Each communication device 1 may function as the transmission device 2 when transmitting the target data. Further, each communication device 1 may function as the receiving device 4 when it becomes the destination of the target data. Each communication device 1 may function as a relay device 3 that relays communication between the transmission device 2 and the reception device 4. Here, the target data is data relating to a request or response transmitted from the transmission device 2 to the reception device 4, and is data to be subjected to proxy communication described later.

  The communication system 5 according to the embodiment of the present invention is provided in a limited space such as inside a passenger car. Each communication device 1 is installed not only in the controller but also in correspondence with each facility such as a car door, room lamp, window, etc., and transmits the state of each facility to the controller or the state of each facility from the controller. Receive instructions to change

  The communication system 5 realizes wireless communication between the communication devices 1 by an ad hoc method. Depending on the position of each communication device 1, the radio wave environment, etc., each communication device 1 may not be able to communicate directly. In the embodiment of the present invention, the first communication device 1a can communicate with the second communication device 1b, but cannot communicate with the third communication device 1c and the fourth communication device 1d. The second communication device 1b can communicate with the first communication device 1a and the third communication device 1c, but cannot communicate with the fourth communication device 1d. The third communication device 1c can communicate with the second communication device 1b and the fourth communication device 1d, but cannot communicate with the first communication device 1a. The fourth communication device 1d can communicate with the third communication device 1c, but cannot communicate with the first communication device 1a and the second communication device 1b.

  In such a situation, when the first communication device 1a tries to transmit the target data to the third communication device 1c, the first communication device 1a and the third communication device 1c cannot directly communicate with each other. The second communication device 1b communicates on behalf of the first communication device 1a (proxy communication).

  Specifically, when the first communication device 1a transmits the target data to the third communication device 1c, communication is performed according to the following procedure.

(1) Overhear When the first communication device 1a transmits the target data to the third communication device 1c, the second communication device 1b performs overhear. In overheard, the second communication device 1b detects that the target data is transmitted from the first communication device 1a to the third communication device 1c. Further, the second communication device 1b detects that the reception notification (Ack) for the target data cannot be received after the target data is transmitted.

(2) Proxy Communication The second communication device 1b performs proxy communication after overhearing. In the proxy communication, the second communication device 1b performs the proxy communication of the target data toward the third communication device 1c instead of the first communication device 1a. After performing the proxy communication, the second communication device 1b waits for a reception notification from the third communication device 1c about the target data that has been proxy communicated. When the reception notification is not received from the third communication device 1c, the second communication device 1b may repeat the proxy communication of the target data at a predetermined time interval and a predetermined number of times.

(3) Notification of Completion of Proxy Communication When the second communication device 1b receives the reception notification from the third communication device 1c in response to the proxy communication of the target data to the third communication device 1c, the first communication device 1b receives the first communication. The device 1a is notified of the completion of proxy communication. Upon receiving the proxy communication completion notification, the first communication device 1a recognizes that the target data has been received by the third communication device 1c. This completes a series of communications for transmitting the target data from the transmission source to the transmission destination.

  In such proxy communication, data relating to proxy communication transmitted and received by the second communication device 1b includes, for example, as shown in FIG. 2, a source address P1 and a destination address P2 as link addresses, a source address P3 and a destination as end addresses. An address P4, a type P5, a sequence number P6 and data P7 are provided. The data regarding proxy communication may include items other than the items shown in FIG.

  The link address specifies the address of the communication device 1 directly connected by Link to Link for the data of the proxy communication performed by the second communication device 1b. As the end address, the address of the end-to-end communication device 1 for transmitting / receiving the target data for the second communication device 1b to perform proxy communication is set. When the second communication device 1b performs proxy communication for communication from the first communication device 1a to the third communication device 1c, the source address P1 of the link address is set to the address of the second communication device 1b, The address of the third communication device 1c is set to the destination address P2. The source address P3 of the end address is set to the address of the first communication device 1a, and the destination address P4 is set to the address of the third communication device 1c. In the type P5, a data type relating to proxy communication such as proxy communication or notification of completion of proxy communication is set. The sequence number P6 is an identifier that identifies target data that triggers proxy communication. A common value is set to the sequence number P6 of each data such as the proxy communication relating to the predetermined target data and the notification of the completion of the proxy communication. The data P7 is data to be transmitted (payload), and the target data is set or a notification of completion is set. The data P7 may have a fixed length or a variable length. When the length is variable, an item indicating the data length may be provided.

(Communication method)
A communication method according to the embodiment of the present invention will be described with reference to FIG. FIG. 3 shows a process when the first communication device 1a transmits target data to the fourth communication device 1d. In the example shown in FIG. 3, the solid line indicates that communication is possible, and the broken line indicates that communication is not possible. In the example shown in FIG. 3, a symbol "#" and a number following "proxy communication", "reception notification" and "notification of completion of proxy communication" identify each data. Further, FIG. 3 omits the step in which the second communication device 1b and the third communication device 1c retransmit the proxy communication and the like.

  First, in step S1, the first communication device 1a transmits the target data to the fourth communication device 1d to attempt direct communication of the target data. After transmitting the target data, the first communication device 1a waits for the notification that the target data is received by the fourth communication device 1d for a predetermined time in step S2. If the fourth communication device 1d does not receive the notification that it has been received within the predetermined time, the first communication device 1a retransmits the target data at a predetermined time interval and a predetermined number of times. The notification that the first communication device 1a waits is a reception notification received from the fourth communication device 1d when the first communication device 1a and the fourth communication device 1d can communicate with each other. However, in the present embodiment, since the first communication device 1a and the fourth communication device 1d cannot communicate with each other, this is a completion notification of proxy communication transmitted by another communication device 1 (second communication device 1b). Here, the first communication device 1a does not retransmit the target data and waits for a notification that the target data is received until step S20 described later.

  The second communication device 1b detects that the target data has been transmitted in step S1 due to overheard, and monitors the reception notification # 1 for the direct communication of the target data in step S3.

  Since the first communication device 1a and the fourth communication device 1d cannot directly communicate with each other, in step S4, the first communication device 1a notifies the fourth communication device 1d of the reception notification for the direct communication of the target data in step S1. You cannot get # 1. When detecting that the reception notification # 1 is not transmitted, the second communication device 1b performs the proxy communication # 1 of the target data to the fourth communication device 1d in step S5. After performing the proxy communication # 1 of the target data, the second communication device 1b waits for a notification that the proxy communication # 1 of the target data has been received by the fourth communication device 1d for a predetermined time in step S6. To do. When the second communication device 1b does not receive the notification that it has been received within the predetermined time, the second communication device 1b retransmits the proxy communication # 1 of the target data at the predetermined time interval and the predetermined number of times. The notification that the second communication device 1b waits is a reception notification from the fourth communication device 1d when the second communication device 1b and the fourth communication device 1d can communicate with each other. However, in the present embodiment, since the second communication device 1b and the fourth communication device 1d cannot communicate with each other, this is a completion notification of proxy communication transmitted by another communication device 1 (third communication device 1c).

  The third communication device 1c detects that the proxy communication # 1 of the target data has been performed in step S5 due to overheard, and monitors the reception notification # 2 to the proxy communication # 1 of the target data in step S7.

  Since the second communication device 1b and the fourth communication device 1d cannot directly communicate with each other, in step S8, the second communication device 1b communicates with the proxy communication # 1 of the target data in step S5 from the fourth communication device 1d. The reception notification # 2 cannot be acquired. Upon detecting that the reception notification # 2 is not transmitted, the third communication device 1c performs the proxy communication # 2 of the target data to the fourth communication device 1d in step S9. After performing the proxy communication # 2 of the target data, the third communication device 1c waits for the notification that the proxy communication # 2 of the target data has been received by the fourth communication device 1d for a predetermined time in step S10. To do. If the third communication device 1c does not receive the notification that it has been received within the predetermined time, the third communication device 1c retransmits the proxy communication # 2 of the target data at the predetermined time interval and the predetermined number of times. The notification that the third communication device 1c waits is a reception notification from the fourth communication device 1d because the third communication device 1c and the fourth communication device 1d can communicate with each other.

  In step S11, the third communication device 1c receives the reception notification # 3 for the proxy communication # 2 in step S9 from the fourth communication device 1d. In step S12, the third communication device 1c discards the data regarding the proxy communication # 2 of the target data transmitted in step S9. In step S13, the third communication device 1c attempts to transmit the proxy communication completion notification # 1 toward the first communication device 1a. After the completion notification # 1 of the proxy communication of the target data is performed, the third communication device 1c receives the completion notification # 1 of the proxy communication of the target data in the first communication device 1a for a predetermined time in step S14. Wait for notification. If the third communication device 1c does not receive the notification that it has been received within the predetermined time, the third communication device 1c retransmits the completion notification # 1 of the proxy communication of the target data at the predetermined time interval and the predetermined number of times.

  The second communication device 1b detects that the proxy communication completion notification # 1 has been transmitted in step S13 due to overheard. In step S15, the second communication device 1b determines that the notification of completion of proxy communication has been transmitted for the target data of the proxy communication data transmitted in step S5, and deletes the proxy communication data transmitted in step S5. The second communication device 1b also monitors the reception notification # 4 of the notification # 1 of completion of proxy communication.

  Since the third communication device 1c and the first communication device 1a cannot directly communicate with each other, in step S16, the third communication device 1c sends the proxy communication completion notification # 1 in step S13 from the first communication device 1a. The reception notification # 4 cannot be acquired. When detecting that the reception notification # 4 is not transmitted, the second communication device 1b transmits a notification of completion of proxy communication # 2 to the first communication device 1a in step S17. The proxy communication completion notification # 2 is a target for proxy communication of the proxy communication completion notification # 1 by the second communication device 1b. After the completion notification # 2 of the proxy communication of the target data is performed, the second communication device 1b receives the completion notification # 2 of the proxy communication of the target data in the first communication device 1a for a predetermined time in step S18. Wait for notification. When the second communication device 1b does not receive the notification that it has been received within the predetermined time, the second communication device 1b retransmits the completion notification # 2 of the proxy communication of the target data at the predetermined time interval and the predetermined number of times.

  If the first communication device 1a cannot receive the proxy communication completion notification # 2 due to a change in the communication environment or the like, the second communication device 1b responds to the proxy communication completion notification # 2 in step S17 in step S19. The reception notification # 5 cannot be acquired.

  On the other hand, in step S2, if the first communication device 1a, which has been waiting for the retransmission or notification of the target data for the predetermined time, does not receive the notification within the predetermined time, the first communication device 1a determines in step S20 that the target Try to resend the data. When the second communication device 1b detects the retransmission of the target data by the first communication device 1a in step S21, the second communication device 1b retransmits the completion notification # 2 of the proxy communication regarding the target data to the first communication device 1a. . Further, the second communication device 1b does not monitor the reception notification and does not perform the proxy communication of the target data regarding the retransmission of the target data by the first communication device 1a.

  As described above, in the communication method according to the embodiment of the present invention, when the notification that the target data is received by the fourth communication device 1d is not received after the first communication device 1a transmits the target data, The first communication device 1a retransmits the target data. When the second communication device 1b detects that the target data is retransmitted, the second communication device 1b recognizes that the target data is received by the fourth communication device 1d, and the target data is the fourth communication device. The notification indicating that it is received by 1d is transmitted to the first communication device 1a. In the example illustrated in FIG. 3, the second communication device 1b knows that the third communication device 1c has transmitted the completion notification # 1 of the proxy communication regarding the target data. It is possible to notify that the target data has been received by the fourth communication device 1d.

  In the conventional communication method, when the first communication device 1a retransmits the target data, the processes of steps S1 to S20 of FIG. 3 are repeated, and the number of traffics in the communication system 5 increases. On the other hand, in the communication method according to the embodiment of the present invention, the second communication device 1b notifies the first communication device 1a that the target data has been received by the fourth communication device 1d. As a result, the first communication device 1a thereafter does not retransmit the target data, and the second communication device 1b does not perform the proxy communication for the retransmitted target data. Can be suppressed. Further, in the communication method according to the embodiment of the present invention, the greater the number of relay devices that relay communication between the transmission device and the reception device, the more remarkable the effect of suppressing the traffic number becomes.

  In the example illustrated in FIG. 3, for the notification of completion of proxy communication # 2 in step S17, the proxy communication is performed when it is detected that the first communication device 1a retransmits the target data after it is determined that the reception notification # 5 cannot be received. Although the case of retransmitting the completion notification # 2 has been described, the present invention is not limited to this. For example, while waiting for the retransmission of the proxy communication completion notification # 2 in step S17, etc., when the retransmission of the target data by the first communication device 1a is detected, the proxy communication completion notification # 2 is detected. May be resent.

  Further, in the example shown in FIG. 3, the second communication device 1b, which has made the proxy communication of the transmission of the target data of the first communication device 1a, acts as a proxy when the retransmission of the target data by the first communication device 1a is detected. Although the case of transmitting the communication completion notification has been described, the present invention is not limited to this. A communication that detects retransmission of target data by the first communication device 1a and recognizes that the target data has been received by the fourth communication device 1d, even if the communication device did not proxy the transmission of the target data. The device 1 may notify the first communication device 1a to that effect.

  Further, in FIG. 3, the case where the first communication device 1a does not retransmit the target data until the target data is retransmitted in step S20 after the notification or the waiting for retransmission in step S2 has been described, but the present invention is not limited to this. Absent. The first communication device 1a may retransmit the target data according to a predetermined condition. In that case, when the second communication device 1b detects the retransmission of the target data by the first communication device 1a, depending on whether the target data has been confirmed to have been transmitted to the fourth communication device 1d, The operation of the second communication device 1b is different.

  If the target data has not been confirmed to have been transmitted to the fourth communication device 1d, proxy communication is performed as in step S3 and thereafter. When the target data has not been confirmed to have been transmitted to the fourth communication device 1d, specifically, in step S13 of FIG. 3, the second communication device 1b exceeds the proxy communication completion notification # 1. This is the case where the first communication device 1a retransmits the target data before hearing. On the other hand, when it is confirmed that the target data has been transmitted to the fourth communication device 1d, as shown in step S21, the second communication device 1b sends the completion notification of the proxy communication regarding the target data to the first communication device 1d. It is transmitted to the communication device 1a. When it is confirmed that the target data has been transmitted to the fourth communication device 1d, specifically, in step S13 of FIG. 3, the second communication device 1b exceeds the proxy communication completion notification # 1. This is a case where the first communication device 1a retransmits the target data after hearing.

(Transmission device)
With reference to FIG. 4, description will be given of transmitting device 2 which is a communication device according to the embodiment of the present invention. The transmission device 2 shown in FIG. 4 corresponds to the first communication device 1a shown in FIG. FIG. 4 shows the configuration when the communication device 1 functions as the transmission device 2, and the configuration when the communication device 1 functions as the relay device 3 or the reception device 4 is omitted.

  The transmission device 2 is a general computer including a storage device 21, a processing device 25, and a communication control device 29. A general computer executes the transmission program to realize the functions shown in FIG.

  The storage device 21 is a ROM (Read Only Memory), a RAM (Random access memory), a hard disk, or the like, and stores various data such as input data, output data, and intermediate data for the processing device 25 to execute processing. . The processing device 25 is a CPU (Central Processing Unit), and reads and writes data stored in the storage device 21 and inputs and outputs data to and from the communication control device 29 to execute processing in the transmission device 2. . The communication control device 29 is an interface for connecting the transmitting device 2 to the other communication devices 1 (the relay device 3 and the receiving device 4) in a communicable manner.

  The storage device 21 stores the transmission program and also the target data T. The target data T is data that the transmission device 2 transmits to the reception device 4.

  The processing device 25 has a transmission unit 26. The transmission unit 26 transmits the target data T to the reception device 4. When the transmitting unit 26 does not receive the notification indicating that the receiving device 4 has received the target data T within the predetermined time after transmitting the target data T to the receiving device 4, the transmitting unit 26 sends the target data T to the receiving device 4. Resend to. The notification indicating that the receiving device 4 has received the target data T is a reception notification indicating that the receiving device 4 has received the target data T from the transmitting device 2 when the transmitting device 2 and the receiving device 4 can directly communicate with each other. is there. On the other hand, when the target data T is transmitted to the receiving device 4 by using the proxy communication by the relay device 3, the notification indicating that the receiving device 4 has received the target data T is a completion notification of the proxy communication of the target data by the relay device 3. Is.

  When the transmitter 26 receives the notification indicating that the receiving device 4 has received the data within a predetermined time after transmitting the target data T to the receiving device 4, the receiving device 4 receives the target data T. Then, the target data T is deleted.

  The transmission process by the transmission unit 26 will be described with reference to FIG.

  First, in step S101, the transmission unit 26 transmits the target data T. In step S102, the transmission unit 26 waits for reception of the reception notification of the target data transmitted in step S101 or the completion notification of proxy communication. When the reception notice or the notice of completion of proxy communication is received, the process is terminated as it is.

  When the reception notification or the proxy communication completion notification is not received in step S102, the transmission unit 26 determines in step S103 whether the retransmission time of the target data T has arrived. Until the retransmission time arrives, the reception of the reception notification or the notification of the completion of the proxy communication is waited in step S102.

  When the retransmission time of the target data T arrives in step S103, the transmission unit 26 retransmits the target data T and counts up the number of retransmissions in step S104. Further, in step S105, the reception of the reception notification of the target data retransmitted in step S104 or the notification of the completion of proxy communication is awaited. When the reception notice or the notice of completion of proxy communication is received, the process is terminated as it is.

  In step S106, the transmission unit 26 determines whether or not the predetermined number of retransmissions has been exceeded. If not exceeded, the process returns to step S102, and in step S102, the transmission unit 26 waits for reception of the reception notification of the target data transmitted in step S104 or the completion notification of proxy communication. When the predetermined number of retransmissions is exceeded in step S105, the transmission unit 26 discards the data related to the target data, abandons the transmission of the target data T in step S107, and ends the process.

(Relay device)
With reference to FIG. 6, the relay device 3 that is the communication device according to the embodiment of the present invention will be described. The relay device 3 shown in FIG. 4 corresponds to the second communication device 1b or the third communication device 1c shown in FIG. FIG. 6 shows the configuration when the communication device 1 functions as the relay device 3, and the configuration when the communication device 1 functions as the transmission device 2 or the reception device 4 is omitted.

  The relay device 3 is a general computer including a storage device 31, a processing device 35, and a communication control device 39. When a general computer executes the relay program, the functions shown in FIG. 6 are realized.

  The storage device 31 is a ROM (Read Only Memory), a RAM (Random access memory), a hard disk, and the like, and stores various data such as input data, output data, and intermediate data for the processing device 35 to execute processing. . The processing device 35 is a CPU (Central Processing Unit), reads and writes data stored in the storage device 31, inputs and outputs data to and from the communication control device 39, and executes processing in the relay device 3. . The communication control device 39 is an interface for connecting the relay device 3 to the other communication devices 1 (the transmission device 2 and the reception device 4) in a communicable manner.

  The storage device 31 stores the relay program and also stores the relay data 32 and the reception re-notification accumulated data 33.

  The relay data 32 is a buffer that holds the data transmitted by the relay unit 37. The relay data 32 is transmitted in the FIFO format, for example. As shown in FIG. 7, the relay data 32 holds respective data such as proxy communication of target data transmitted from the transmission device 2 and not notified of reception by the reception device 4, notification of completion of proxy communication, and the like. When each data is retransmitted at a predetermined time interval and a predetermined number of times, the relay data 32 may be associated with information such as a timer for measuring the number of times of retransmission and the time until retransmission.

  The reception re-notification accumulated data 33 is a buffer that holds the data transmitted by the reception re-notification unit 38. As shown in FIG. 8, the reception re-notification accumulated data 33 retains each data of the completion notification of the proxy communication in which the relay device 3 transmits the completion notification of the proxy communication but does not receive the reception notification from the transmission device 2. To do. Each data of the reception re-notification accumulated data 33 is transmitted when the transmitter 2 retransmits the related target data T. Each data of the reception re-notification accumulated data 33 is retained after being retained for a predetermined time and then discarded, and as shown in FIG. 8, the time to wait for retransmission before being discarded is associated.

  The reception re-notification accumulated data 33 may hold the data for which the reception notification is not obtained even when the relay unit 37 retransmits the data at a predetermined time interval and a predetermined number of times. Further, the reception re-notification accumulated data 33 may retain data for which a reception notification cannot be obtained regardless of whether or not the relay unit 37 retransmits the reception re-notification a predetermined number of times.

  The processing device 25 includes an over-hear processing unit 36, a relay unit 37, and a reception re-notification unit 38.

  The over-hear processing unit 36 detects that the transmission device 2 has transmitted the target data T to the reception device 4, but the reception notification indicating that the reception device 4 has received the target data T is not transmitted. In this case, the target data is stored in the relay data 32. When the transmitting device 2 transmits data to the receiving device 4, the overhear processing unit 36 temporarily stores the data in the storage device 31. When detecting that the reception notification indicating that the receiving device 4 has received this data is not transmitted within the predetermined time, the overheard processing unit 36 stores the temporarily stored data in the relay data 32, and the proxy unit 37 substitutes the data. Prepare for communication.

  Overhear processing by the overhear processing unit 36 will be described with reference to FIG. 9.

  When detecting the communication data transmitted / received in the receivable area in step S201, the overhear processing unit 36 determines the type of the detected communication data in step S202.

  When the detected communication data relates to the retransmission of the target data T by the transmission device 2, the reception re-notification unit 38 is notified in step S203 that the target data T has been retransmitted, the sequence number of the target data T, and the like. When the reception re-notification unit 38 recognizes that the target data T is received by the reception device 4 according to the notification content from the over-hear processing unit 36, the reception re-notification unit 38 indicates that the target data T is received by the reception device 4. Notify the transmitter 2. The overhear processing unit 36 determines whether or not the detected communication data relates to the retransmission of the target data T by the transmission device 2 by referring to, for example, a log.

  On the other hand, if the detected communication data is the first transmission of the target data T or the completion notification of the proxy communication, the process proceeds to step S204. In step S204, the overhear processing unit 36 determines whether or not the reception notification for the communication data has been transmitted. When the reception notification is transmitted, the overhear processing unit 36 ends the processing. If not transmitted, the over-hear processing unit 36 stores the communication data detected in step S201 in the relay data 32 in step S205, and ends the process. The data stored in the relay data 32 is proxy-communicated by the relay unit 37.

  When the relay unit 37 performs the proxy communication of the target data T stored in the relay data 32 toward the receiving device 4 and receives the “notification” indicating that the receiving device 4 has received the target data T, the transmitting device 2 Send a notification to. When the relay unit 37 does not receive the notification indicating that the receiving device 4 has received the target data T, the relay unit 37 may repeat the proxy communication of the target data T for a predetermined time interval and a predetermined number of times.

  As shown in the embodiment of the present invention, when the second communication device 1b cannot communicate with the fourth communication device 1d that is the transmission destination of the target data T, the “notification” received by the relay unit 37 is 3 is a notice of completion of proxy communication transmitted by the third communication device 1c (another relay device). The third communication device 1c (another relay device) targets the fourth communication device 1d (reception device 4) in contrast to the second communication device 1b (relay device 3) performing proxy communication of the target data T. When it is detected that the reception notification indicating that the data T has been received is not transmitted, the target data T is further proxy-communicated with the fourth communication device 1d (reception device 4). When the third communication device 1c receives a reception notification from the fourth communication device 1d (reception device 4) indicating that the target data T has been received by further proxy communication, the third communication device 1c sends a completion notification of the proxy communication to the second communication device 1d. To the communication device 1b (relay device 3).

  The relay unit 37 further receives a reception notification indicating that the transmission device 2 has received the notification of completion of proxy communication, in response to the notification of completion of proxy communication by the third communication device 1c (another relay device). When it is detected that the communication has not been transmitted, the third communication device 1c (another relay device) transmits the notification of the completion of the proxy communication by proxy communication. The relay unit 37 repeatedly transmits the proxy communication completion notification at a predetermined time interval and a predetermined number of times, and when the reception notification cannot be received from the transmission device 2, the reception re-notification accumulated data 33 is notified of the proxy communication completion notification. accumulate.

  The relay process by the relay unit 37 will be described with reference to FIG.

  First, in step S301, processing is sorted according to the type of data overheard by the overheard processing unit 36. In the case of the target data T, the relay unit 37 performs proxy communication of the target data T in step S302. When the reception notification of the target data T is not received from the receiving device 4 in step S303, the relay unit 37 waits for the retransmission of the target data T in step S304. On the other hand, when the reception notification is received from the reception device 4, the relay unit 37 discards the data related to the target data T from the relay data 32 in step S311, and proceeds to step S321.

  In step S321, the relay unit 37 transmits a notification of completion of proxy communication of the target data T to the transmission device 2. In step S322, the relay unit 37 determines whether or not the reception notification has been received from the transmission device 2 with respect to the completion notification of the proxy communication transmitted in step S321. When the reception notification is received from the transmission device 2, the relay unit 37 discards the data related to the proxy communication completion notification in step S323. On the other hand, when the completion notification of the proxy notification is not received from the transmission device 2, the relay unit 37 waits for the retransmission of the completion notification of the proxy communication in step S324.

  On the other hand, when the data type overheard by the overhear processing unit 36 is the notification of completion of proxy communication, the relay unit 37 has the data related to the target data T for the notification of completion of proxy communication in the relay data 32 in step S310. Or not. If the relay unit 37 has data related to the target data T for the completion notification of the proxy communication, the relay unit 37 discards the data related to the target data T from the relay data 32 in step S311, and proceeds to step S321.

  In step S321, the relay unit 37 transmits a notification of completion of proxy communication (proxy communication) to the transmission device 2. The proxy communication completion notification transmitted here is data that was transmitted to another transmission device 2 by another relay device but was not received by the transmission device 2. In step S322, when the reception notification is received from the transmission device 2 in response to the completion notification of the proxy communication transmitted in step S321, the data related to the completion notification of the proxy communication is discarded in step S323. On the other hand, when the completion notification of the proxy notification is not received from the transmission device 2, the completion notification of the proxy communication is retransmitted in step S324.

  With reference to FIG. 11, a process in which the relay unit 37 retransmits the target data T after step S304 in FIG. 10 will be described. The target data T is retransmitted a predetermined number of times at a predetermined time interval.

  If the retransmission time of the target data T has not arrived in step S401, the arrival of the retransmission time is awaited. When the retransmission time has arrived, the relay unit 37 retransmits the target data T to the receiving device 4 and counts up the number of retransmissions in step S402. Furthermore, in step S403, the relay unit 37 waits for the reception notification or the notification of proxy communication completion regarding the target data T transmitted in step S402. Upon receiving the reception notification or the proxy communication completion notification, in step S404, the proxy communication completion notification is transmitted to the transmission device 2, and the reception notification for the proxy communication completion notification is awaited. When the reception notification is received from the transmission device 2 in step S405, the target data and the data related to the completion notification of the proxy communication are discarded in step S406. On the other hand, if the reception notification for the completion notification of the proxy communication is not received from the transmission device 2 in step S405, the relay unit 37 waits for the retransmission of the completion notification of the proxy communication in step S407.

  In step S403, when the reception notification is not received from the receiving device 4 for the retransmission of the target data T transmitted in step S402, the relay unit 37 determines in step S408 whether the number of retransmissions has exceeded. If not, the relay unit 37 ends the process as it is and waits for the arrival of the next retransmission time. In the case of over, in step S409, the relay unit 37 discards the target data and the data related to the completion notification of the proxy communication, and ends the process.

  With reference to FIG. 12, the process in which the relay unit 37 retransmits the proxy communication completion notification in step S324 and subsequent steps in FIG. 10 and step S407 and subsequent steps in FIG. 11 will be described.

  If the retransmission time of the proxy communication completion notification has not arrived in step S501, the arrival of the retransmission time is awaited. When the retransmission time has arrived, in step S502, the relay unit 37 retransmits the proxy communication completion notification to the transmission device 2 and counts up the number of retransmissions. Furthermore, in step S503, the relay unit 37 waits for the reception notification of the completion notification of the proxy communication transmitted to the transmission device 2 in step S502. Upon receiving the reception notification, the relay unit 37 discards the data related to the proxy communication completion notification in step S504.

  When the reception notification of the completion notification of the proxy communication transmitted in step S502 is not received in step S503, the relay unit 37 determines in step S505 whether or not the number of retransmissions has exceeded. If the number of retransmissions has not exceeded, the relay unit 37 ends the processing as it is and waits for the arrival of the next retransmission time. When the number of retransmissions is over, the relay unit 37 stores the completion notification of the proxy communication transmitted to the transmission device 2 in the reception re-notification accumulated data 33 in step S506, and ends the process. The notification of completion of proxy communication stored in the reception re-notification accumulated data 33 is processed by the reception re-notification unit 38.

  When the retransmission of the target data T by the transmission device 2 is detected, the reception re-notification unit 38 transmits, to the transmission device 2, a “notification” indicating that the reception device 4 has received the target data T.

  The relay device 3 receives the reception notification from the receiving device 4 or performs the proxy communication of the target data T, or receives the completion notification of the proxy communication from another relay device. It will be understood that the data T has been received. In the embodiment of the present invention, the second communication device 1b (relay device 3) cannot communicate with the fourth communication device 1d (reception device 4). Is a notice of completion of proxy communication with which the relay unit 37 performs proxy communication. In this proxy communication completion notification, the relay unit 37 performs proxy communication of the proxy communication completion notification transmitted from the third communication device 1c (another relay device) to the first communication device 1a (transmission device 2). Is.

  The reception re-notification unit 38, among the plurality of proxy communication completion notifications included in the reception re-notification accumulated data 33, transmits the re-transmission target data and the completion notification of the proxy communication in which the two addresses of the sequence number and the end address are common. Check for the presence.

  The notification of completion of proxy communication is a reply to the transmission of the target data. Therefore, the reception re-notification unit 38 determines whether or not the transmission source address of the end address of the target data transmitted by the transmission device 2 matches the destination address of the proxy communication completion notification transmitted by the relay device 3. Further, the reception re-notification unit 38 determines whether or not the destination address of the end address of the target data transmitted by the transmission device 2 matches the transmission source address of the proxy communication completion notification transmitted by the relay device 3.

  When the sequence number and each address match, the reception re-notification unit 38 transmits a completion notification having a common sequence number and the like to the transmission device 2. On the other hand, if they do not have a common completion notification, the reception re-notification unit 38 may be proxy communicated by the relay unit 37 without transmitting the completion notification to the transmission device 2. In the embodiment of the present invention, the reception re-notification unit 38 determines whether or not the reception device 4 has a “notification” indicating that the target data T has been received, based on the sequence number and the address, but this is not the only option. I can't. For example, the reception re-notification unit 38 may make the determination based only on the sequence number.

  When the retransmission notification of the target data T by the transmission device 2 is detected after the reception re-notification unit 38 receives the reception notification regarding the target data T or the completion notification of the proxy communication, the reception device 4 notifies the reception device 4 of the target data T. Send a notification that T has been received. In addition, when the retransmission of the target data T by the transmission device 2 is detected before receiving the reception notification or the notification of the completion of the proxy communication regarding the target data T, the relay unit 37 performs the proxy communication of the target data T.

  When the relay unit 37 transmits the notification of the completion of the proxy communication to the transmission device 2 and the overheard processing unit 36 detects the retransmission of the target data T by the transmission device 2 before a predetermined time elapses, the reception re-notification is performed. The unit 38 retransmits to the transmitting device 2 a notification indicating that the receiving device 4 has received the target data T. On the other hand, when the relay unit 37 transmits a notification of the completion of proxy communication to the transmission device 2 and a predetermined time has elapsed, and the overheard processing unit 36 does not detect the retransmission of the target data T by the transmission device 2, reception re-notification The unit 38 discards the data related to the notification indicating that the receiving device 4 has received the target data T. When the relay unit 37 does not receive the reception confirmation with respect to the completion notification of the proxy communication related to the target data T, the completion notification of the proxy communication is held for a predetermined time. If the retransmission of the target data T by the transmission device 2 is not detected while the transmission device 2 holds the predetermined time, the reception re-notification unit 38 discards the data related to the completion notification of the proxy communication. In this case, it is considered that the transmission device 2 has received from the other communication device 1 a notification indicating that the reception device 4 has received the target data T, or has abandoned the transmission of the target data T.

  The reception re-notification processing by the reception re-notification unit 38 will be described with reference to FIG. The process shown in FIG. 13 is executed after the process shown in step S506 of FIG.

  First, in step S601, when the reception re-notification unit 38 detects the retransmission of the target data T by the transmission device 2, the process proceeds to step S602. When the over-hear processing unit 36 intercepts the surrounding communication and detects the retransmission of the target data T by the transmission device 2, the over-hear processing unit 36 notifies the reception re-notification unit 38 that the retransmission of the target data T is detected. You may notify. When the predetermined time elapses without detecting the retransmission of the target data T by the transmission device 2, the reception re-notification unit 38 ends the process as it is. At this time, the reception re-notification unit 38 deletes the data related to the target data T from the reception re-notification accumulated data 33.

  In step S602, the reception re-notification unit 38 determines whether or not the reception re-notification accumulated data 33 retains the completion notification of the proxy communication related to the target data T for which the retransmission is detected. The reception re-notification unit 38 determines whether or not the reception re-notification accumulated data 33 holds a notice of completion of proxy communication having a common sequence number and the like. If not held, the reception re-notification unit 38 ends the process as it is.

  If held, the reception re-notification unit 38 retransmits to the transmission device 2 the completion notification of the proxy communication specified in step S602 that the sequence numbers and the like are common in step S603. The reception re-notification unit 38 waits for the reception notification transmitted from the transmission device 2 with respect to the proxy communication completion notification transmitted in step S603.

  In step S604, when the reception notification for the proxy communication completion notification is received from the transmission device 2, the reception re-notification unit 38 in step S605 receives the reception re-notification of the data related to the proxy communication completion notification transmitted in step S603. Discard from the accumulated data 33. On the other hand, if the notice of completion of proxy communication is not received, the reception re-notification unit 38 waits for retransmission of the notice of completion of proxy communication transmitted in step S603 in step S606. When the reception re-notification unit 38 does not receive the reception notification even after resending the proxy communication completion notification at a predetermined time interval and a predetermined number of times, the proxy communication completion notification is stored again in the reception re-notification accumulated data 33. After that, when the retransmission of the target data T is not detected from the transmission device 2 while being accumulated in the reception re-notification accumulated data 33 for a predetermined time, the data related to the completion notification of the proxy communication related to the target data T is the reception re-notification. It is discarded from the accumulated data 33. When the retransmission of the target data T is detected from the transmission device 2 while being accumulated in the reception re-notification accumulated data 33 for a predetermined time, the completion notification of the proxy communication is retransmitted to the transmission device 2 as in the processing from step S601. To be done.

  Note that in the embodiment of the present invention, after the relay unit 37 does not receive the reception notification from the transmission device 2 even if the notification of the completion of the proxy communication is retransmitted to the transmission device 2 at the predetermined time interval and the predetermined number of times. The reception re-notification unit 38 has transmitted the proxy communication completion notification, but the reception re-notification unit 38 sends the proxy communication completion notification to the transmission device 2 at a predetermined time interval and a predetermined number of times. Even before the retransmission is completed, the reception re-notification unit 38 may transmit the proxy communication completion notification when the retransmission of the target data T by the transmission device 2 is detected.

  According to the communication system 5 according to the embodiment of the present invention as described above, the relay device 3 performs the proxy communication of the target data T, and receives the notification indicating that the target data T is received by the receiving device 4. Later, when the transmitter 2 retransmits the target data T, the notification is transmitted to the transmitter 2. Conventionally, the relay device 3 performs proxy communication of the target data T regardless of whether or not the retransmitted target data T is received by the receiving device 4, so that the traffic amount may increase. On the other hand, according to the embodiment of the present invention, when the target data T is received by the receiving device 4, a notification to that effect is transmitted to the transmitting device 2. As a result, the communication system 5 according to the embodiment of the present invention avoids the situation in which the relay device 3 performs proxy communication of the target data T regardless of whether or not the retransmitted target data T is received by the receiving device 4. Therefore, it is possible to avoid an increase in traffic volume.

(Modification)
In the embodiment of the present invention, the second communication device 1b (relay device 3) cannot directly communicate with the fourth communication device 1d (reception device 4), and the third communication device 1c (another relay device) is used. Although the case of communicating with the fourth communication device 1d by proxy communication has been described, the present invention is not limited to this. In the modification, the case where the second communication device 1b can directly communicate with the fourth communication device 1d will be described.

  The communication system 5'shown in FIG. 14 includes a first communication device 1a, a second communication device 1b, and a fourth communication device 1d. Although FIG. 14 includes three communication devices, the number of communication devices is not limited to this.

  In the communication system 5'according to the modified example, the first communication device 1a can communicate with the second communication device 1b, but cannot communicate with the fourth communication device 1d. The second communication device 1b can communicate with the first communication device 1a and the fourth communication device 1d. The fourth communication device 1d can communicate with the second communication device 1b, but cannot communicate with the first communication device 1a.

  In such a situation, when the first communication device 1a tries to transmit the target data to the fourth communication device 1d, the first communication device 1a and the fourth communication device 1d cannot directly communicate with each other. The second communication device 1b communicates on behalf of the first communication device 1a (proxy communication).

  The first communication device 1a functions as the transmission device 2, and the fourth communication device 1d functions as the reception device 4. In the modification, the second communication device 1b functions as the relay device 3'and has the same configuration as the relay device 3 described with reference to FIG.

  However, the notification that the relay unit 37 receives and that the target data T has been received by the reception device 4 is a reception notification that the reception device 4 indicates that the relay unit 37 has received the target data. Since the relay device 3 ′ and the receiving device 4 can communicate with each other, the relay unit 37 transmits the proxy communication of the target data to the receiving device 4 and, when receiving the reception notification for the proxy communication from the receiving device 4, receives the receiving device. 4 recognizes that the target data has been received.

  In addition, when the re-notification unit 38 detects that the target data is retransmitted, the reception re-notification unit 38 transmits, to the transmission device 2, a proxy communication completion notice indicating that the proxy communication transmitted by the relay device 3 ′ has been completed.

  A communication method according to the modification will be described with reference to FIG.

  First, in step S51, the first communication device 1a transmits the target data to the fourth communication device 1d, and tries to directly communicate the target data. After transmitting the target data, the first communication device 1a waits for the notification that the target data is received by the fourth communication device 1d for a predetermined time in step S52. When the second communication device 1b does not receive the notification that it has been received by the fourth communication device 1d within the predetermined time, the second communication device 1b retransmits the target data a predetermined time interval and a predetermined number of times. The notification that the first communication device 1a waits is a reception notification received from the fourth communication device 1d when the first communication device 1a and the fourth communication device 1d can communicate with each other. However, in the modified example, since the first communication device 1a and the fourth communication device 1d cannot communicate with each other, this is the completion notification of the proxy communication transmitted by the second communication device 1b. Here, the first communication device 1a waits for notification and retransmission that the target data has been received by the fourth communication device 1d until step S60 described later.

  The second communication device 1b detects that the target data has been transmitted in step S51 due to overheard, and monitors the reception notification # 1 for the direct communication of the target data in step S53.

  Since the first communication device 1a and the fourth communication device 1d cannot directly communicate with each other, in step S54, the first communication device 1a notifies the fourth communication device 1d of the reception notification for the direct communication of the target data in step S51. You cannot get # 1. When detecting that the reception notification # 1 is not transmitted, the second communication device 1b performs the proxy communication # 1 of the target data to the fourth communication device 1d in step S55.

  In step S56, when the second communication device 1b receives the reception notification # 2 with respect to the proxy communication # 1 of the target data T transmitted in step S55, the second communication device 1b transmits the proxy communication # 1 of step S55 in step S57. Discard the data. In step S58, the completion notification # 1 of the proxy communication is transmitted to the first communication device 1a. The second communication device 1b transmits the completion notification # 1 of the proxy communication of the target data, and then the completion notification # 1 of the proxy communication of the target data is received by the first communication device 1a for a predetermined time in step S59. Wait for notification. If the second communication device 1b does not receive the notification that it has been received by the first communication device 1a within the predetermined time, the second communication device 1b retransmits the proxy communication completion notification # 1 of the target data for a predetermined time interval and a predetermined number of times. To do.

  If the first communication device 1a cannot receive the proxy communication completion notification # 1 due to a change in the communication environment or the like, the second communication device 1b responds to the proxy communication completion notification # 1 in step S58 in step S60. The reception notification # 3 cannot be acquired.

  On the other hand, in step S52, if the first communication device 1a, which has been waiting for the retransmission or notification of the target data for the predetermined time, does not receive the notification within the predetermined time, the first communication device 1a determines in step S61 that the target Try to resend the data. When the second communication device 1b detects the retransmission of the target data by the first communication device 1a in step S62, the second communication device 1b retransmits the completion notification # 1 of the proxy communication regarding the target data to the first communication device 1a. .

  Thus, even if the relay device 3 ′ can directly communicate with the transmitting device 2 and the receiving device 4, when the relay device 3 ′ detects the retransmission of the target data by the transmitting device 2, the relay device 3 ′ transmits the data. It is possible to resend the proxy communication completion notification indicating that the proxy communication has been completed. Also in the communication system 5'according to the modification shown in FIG. 14, it is possible to avoid an increase in traffic volume, as in the embodiment of the present invention.

(Other embodiments)
As described above, the embodiments of the present invention and the modifications thereof have been described, but it should not be understood that the description and drawings forming a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples, and operation techniques will be apparent to those skilled in the art.

  For example, the communication device described in the embodiment of the present invention may be configured on one piece of hardware as shown in FIG. 4 or FIG. 6, or on a plurality of pieces of hardware depending on the function and the number of processes. May be configured as. It may also be realized on an existing processing device.

  Further, although the communication system according to the embodiment of the present invention has been described on the premise of an ad hoc network, the communication system may be applied to other networks such as a mobile network including a base station and a mobile station.

  In addition, in the embodiment and the modified example of the present invention, “predetermined” may be attached to “time”, “time interval”, “number of times”, “number of times of retransmission” and the like. This "predetermined" is used in the sense of "predetermined" or "specified by a predetermined procedure", and an appropriate value is set appropriately. Further, it does not mean that a value common to “predetermined” is set. For example, the same time is not set in all the locations described as "predetermined time".

  It goes without saying that the present invention includes various embodiments and the like not described here. Therefore, the technical scope of the present invention is defined only by the matters specifying the invention according to the scope of claims reasonable from the above description.

1 Communication Device 2 Transmission Device 3 Relay Device 4 Reception Device 5 Communication System 21, 31 Storage Device 25, 35 Processing Device 26 Transmission Unit 29, 39 Communication Control Device 32 Relay Data 33 Reception Re-Notification Accumulated Data 36 Overhear Processing Unit 37 Relay Part 38 Reception re-notification part T Target data

Claims (6)

A communication system comprising a plurality of devices,
A transmitter for transmitting the target data,
A receiving device that is the destination of the target data,
A relay device capable of communicating with the transmission device,
The transmitter is
When the target data is transmitted to the receiving device, and within a predetermined time after transmitting the target data to the receiving device, the receiving device does not receive a notification indicating that the target data has been received, A transmitter for retransmitting the target data to the receiver,
The relay device is
When the transmission device detects that the reception notification indicating that the reception device has received the target data is not transmitted in response to the transmission of the target data toward the reception device, the target data is relayed data. And an overhear processing unit to store in
When the target data stored in the relay data is proxy-communicated toward the receiving device and the notification indicating that the receiving device has received the target data is received, the notification is transmitted to the transmitting device. Relay section,
A communication system, comprising: a reception re-notification unit for transmitting the notification to the transmission device when the retransmission of the target data by the transmission device is detected. A relay device used in a communication system including a plurality of devices,
The communication system is
A transmitter for transmitting the target data,
A receiving device that is the destination of the target data,
A relay device capable of communicating with the transmission device,
The relay device is
When the transmission device detects that the reception notification indicating that the reception device has received the target data is not transmitted in response to the transmission of the target data toward the reception device, the target data is relayed data. And an overhear processing unit to store in
When the target data stored in the relay data is proxy-communicated toward the receiving device and the notification indicating that the receiving device has received the target data is received, the notification is transmitted to the transmitting device. Relay section,
A relay device comprising: a reception re-notification unit that transmits the notification to the transmission device when the retransmission of the target data by the transmission device is detected. By the relay unit, to the transmission device, after a predetermined time has elapsed after transmitting the notification, if the retransmission of the target data by the transmission device is not detected, the reception re-notification unit discards the notification,
The reception re-notification unit re-sends the notification to the transmission device when a retransmission of the target data by the transmission device is detected before a predetermined time elapses. Relay device. The relay device is further communicable with the receiving device,
The notification received by the relay unit is a reception notification indicating that the receiving device has received the target data in the proxy communication,
The relay device according to claim 2, wherein the notification transmitted by the reception re-notification unit is a notification of completion of proxy communication. The communication system further includes another relay device capable of communicating with the relay device and the receiving device,
The notification received by the relay unit detects that the reception apparatus has not transmitted a reception notification indicating that the reception apparatus has received the target data, whereas the relay apparatus has performed proxy communication with the target data. When another relay device receives a reception notification indicating that the target data has been received by further proxy communication from the receiving device, in contrast to the fact that the target data has been further proxy communicated to the receiving device, Completion notification of proxy communication sent by the relay device,
The relay unit detects that the reception notification indicating that the transmission device has received the completion notification of the proxy communication has not been transmitted, while the other relay device has transmitted the completion notification of the proxy communication. In case of, the proxy communication of the completion notification of the proxy communication transmitted by the other relay device,
The relay device according to claim 2, wherein the notification transmitted by the reception re-notification unit is a notification of completion of the proxy communication in which the relay unit performs proxy communication. A communication method used in a communication system including a plurality of devices,
The communication system is
A transmitter for transmitting the target data,
A receiving device that is the destination of the target data,
A relay device capable of communicating with the transmission device,
The transmitter transmits the target data to the receiver,
When the relay device detects that the transmission device has transmitted the target data toward the reception device, but the reception notification indicating that the reception device has received the target data is not transmitted, Storing the target data in the relay data,
When the relay device directs the target data stored in the relay data to the receiving device and receives a notification indicating that the receiving device has received the target data, the notification is sent to the transmitting device. The step of sending
When the transmission device does not receive a notification indicating that the reception device has received the target data within a predetermined time after transmitting the target data to the reception device, the target data is transmitted to the reception device. Resending towards,
The communication method, wherein the relay device comprises a step of transmitting the notification to the transmission device when the retransmission of the target data by the transmission device is detected.

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