JP2005094371A - Data communications equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide data communications equipment for performing retransmission control according to the communication state. <P>SOLUTION: A data comparing part 26 compares data acquired from an on-vehicle terminal 10 with data that has been already stored in a data storing part 24, and discards the acquired data when the acquired data is the same as the data stored in the data storing part 24. When the acquired data are different from the data stored in the data storing part 24, the acquired data are stored in the data storage part 24. As a result of this, when interruption of radio communication is prolonged and a prescribed time which is the waiting time for acknowledgement repeatedly passes to output a plurality of pieces of retransmission data, corresponding to the same data to a communication terminal 20 from the on-vehicle terminal 10, the plurality of pieces of retransmission data are prevented from being stacked in the data storing part 24. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a data communication apparatus, and more particularly, to a data communication apparatus that retransmits data.

  With recent advances in wireless communication technology, it has become possible to send and receive various information in a mobile vehicle. For example, a technology is known in which an information center and an in-vehicle terminal mounted on an automobile are connected via wireless communication, and information is exchanged between the information center and the automobile (see Patent Document 1). A problem in wireless communication using an in-vehicle terminal is the deterioration of the communication state due to the traveling state of the automobile. For example, wireless communication may be interrupted while traveling in a tunnel or the like.

  As a countermeasure when data cannot be transmitted / received normally due to deterioration of the communication state, for example, the following countermeasure is taken in the protocol (TCP / IP) used on the Internet. In TCP / IP, when a data packet is transmitted from a transmitting terminal to a receiving terminal, the receiving terminal returns an acknowledgment indicating that the data packet has been received to the transmitting terminal. The transmitting terminal can determine whether or not the data packet has been successfully transmitted based on the presence or absence of this confirmation response. If the confirmation response is not acquired within a predetermined time, the transmitting terminal retransmits the data packet for which the confirmation response cannot be obtained.

  Therefore, by using TCP / IP in the wireless communication by the in-vehicle terminal, it becomes possible to cope to some extent with respect to the deterioration of the communication state due to the traveling state of the automobile. That is, even when normal data transmission cannot be performed due to deterioration of the communication state or the like, data is retransmitted after the communication state is recovered, so that the reliability of data communication can be improved.

Japanese Patent Laid-Open No. 2002-19548

  However, in the retransmission of data using TCP / IP, if the interruption time during which wireless communication is interrupted is prolonged and a predetermined time, which is a waiting time for an acknowledgment response, repeatedly elapses, the retransmission is repeated. In other words, when the in-vehicle terminal performs wireless communication of data via the communication terminal, retransmission is performed one after another from the in-vehicle terminal to the communication terminal during the interruption time, and the transmission data having the same content is stored in the communication terminal. It will get stuck. When the communication state recovers in this state, transmission data stacked in the communication terminal is transmitted one after another, and unnecessary retransmission data is repeatedly transmitted wirelessly.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a data communication apparatus that performs retransmission control according to a communication situation.

  In order to achieve the above object, a data communication apparatus according to a preferred aspect of the present invention is a data communication apparatus including an in-vehicle terminal and a communication terminal, wherein the in-vehicle terminal outputs data to be transmitted to the communication terminal. Output means, and the communication terminal has transmission means for transmitting a communication signal corresponding to the communication data acquired from the in-vehicle terminal to the receiving side device by wireless communication, and the transmission means is acquired from the in-vehicle terminal. When the communication data is retransmission data related to already acquired communication data, a communication signal corresponding to the acquired communication data is transmitted, and a communication signal corresponding to the retransmission data is not transmitted. According to the above configuration, it is possible to avoid unnecessary retransmission data being repeatedly transmitted by radio.

  Preferably, the communication terminal compares the communication data acquired from the in-vehicle terminal, the communication data acquired from the in-vehicle terminal and the communication data already acquired stored in the storage means, A data comparison unit that determines that the acquired communication data is retransmission data when the acquired communication data and the already acquired communication data are communication data corresponding to the same content; .

  In order to achieve the above object, a data communication apparatus according to a preferred aspect of the present invention is a data communication apparatus including an in-vehicle terminal and a communication terminal, and the in-vehicle terminal outputs communication data to the communication terminal. The communication terminal has a transmission means for transmitting a communication signal corresponding to the communication data acquired from the in-vehicle terminal to the reception side device by wireless communication, and the data output means has the wireless The output of the communication data is controlled according to a communication interruption state.

  Preferably, the communication terminal further includes interruption time measuring means for measuring the interruption time of the wireless communication, and the in-vehicle terminal includes interruption time confirmation means for confirming the interruption time measured by the interruption time measurement means. Furthermore, it is characterized by having. More preferably, the data output means stops outputting the communication data during a stop period corresponding to the interruption time confirmed by the interruption time confirmation means. According to the above configuration, unnecessary repetition of retransmission data during wireless communication interruption time is avoided. Therefore, when communication is resumed, unnecessary retransmission data is not transmitted, and appropriate communication data can be transmitted.

  Preferably, the communication terminal further includes communication state notification means for notifying the in-vehicle terminal of communication state information indicating a state where the wireless communication is being executed or a state where the wireless communication is interrupted. And More preferably, the data output means stops outputting the communication data in a state where the wireless communication is interrupted. According to the above configuration, unnecessary repetition of retransmission data in a state where wireless communication is interrupted is avoided. Therefore, when communication is resumed, unnecessary retransmission data is not transmitted, and appropriate communication data can be transmitted.

  With the configuration described above, retransmission control can be performed according to the communication status.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.

  FIG. 1 shows a preferred embodiment 1 of a data communication apparatus according to the present invention, and FIG. 1 is an overall configuration diagram thereof.

  The data communication device 2 including the in-vehicle terminal 10 and the communication terminal 20 is mounted on a car and used by a passenger. The in-vehicle terminal 10 is an information providing device that provides various information to a passenger such as car navigation. Further, the communication terminal 20 performs wireless communication with a receiving side terminal that exists in a remote place such as a mobile phone. The information center 30 provides information in response to a request from the in-vehicle terminal 10.

  The in-vehicle terminal 10 and the communication terminal 20 can exchange data by wire or wireless, and the in-vehicle terminal 10 transmits / receives data to / from the information center 30 via the communication terminal 20. That is, data transmitted from the in-vehicle terminal 10 to the information center 30 is output from the data output unit 12 to the data storage unit 24 of the communication terminal 20, subjected to signal processing for communication, and wirelessly transmitted from the transmission unit 22. . The wirelessly transmitted data is transferred to the information center 30 via the antenna 32.

  Data transmission / reception between the in-vehicle terminal 10 and the information center 30 is executed based on a protocol (TCP / IP) used on the Internet. The following transmission / reception confirmation is performed by using TCP / IP. When data is transmitted from the in-vehicle terminal 10 to the information center 30 and the information center 30 correctly receives the data, the information center 30 transmits an acknowledgment to the in-vehicle terminal 10. The in-vehicle terminal 10 can confirm that the data transmitted by itself is correctly received by the information center 30 by receiving the confirmation response.

  However, due to some trouble, there may occur a situation where the information center 30 cannot receive data correctly and the confirmation response is not transmitted to the in-vehicle terminal 10. In order to cope with this situation, the retransmission control unit 14 of the in-vehicle terminal 10 instructs the data output unit 12 to retransmit the same data as the data for which the confirmation response cannot be obtained when the confirmation response is not received within a predetermined time. .

  However, in a situation where the in-vehicle terminal 10 is used while the automobile is running, there are many cases where wireless communication is interrupted, for example, when the automobile passes through a tunnel. If wireless communication is interrupted, data output from the in-vehicle terminal 10 is not normally transferred to the information center 30 and a confirmation response cannot be obtained within a predetermined time, so that retransmission data is output from the in-vehicle terminal 10 to the communication terminal 20. Is done. When the interruption of wireless communication is prolonged and a predetermined time, which is a waiting time for confirmation response, repeatedly elapses, a plurality of retransmission data corresponding to the same data is output from the in-vehicle terminal 10 to the communication terminal 20 and the data storage unit 24 of the communication terminal 20 A plurality of retransmitted data are stacked in the same manner. Thereafter, when the wireless communication is recovered and the data stored in the data storage unit 24 is transmitted in order, the stacked retransmission data is repeatedly transmitted.

  Therefore, the data comparison unit 26 compares the data acquired from the in-vehicle terminal 10 with the data already stored in the data storage unit 24, and the acquired data is the same as the data stored in the data storage unit 24. Discard the acquired data. On the other hand, when the acquired data is different from the data stored in the data storage unit 24, the acquired data is stored in the data storage unit 24. Since the data stored in the data storage unit 24 is untransmitted data, transmission is performed sequentially, and each data is deleted from the data storage unit 24 when transmission is completed. As a result, a plurality of retransmission data corresponding to the same data is not stacked in the data storage unit 24 of the communication terminal 20, and repeated transmission of retransmission data when wireless communication is recovered is avoided.

  FIG. 2 shows a preferred embodiment 2 of the data communication apparatus according to the present invention, and FIG. 2 is an overall configuration diagram thereof.

  The data communication device 2 shown in FIG. 2 is composed of an in-vehicle terminal 10 and a communication terminal 20 similar to that shown in FIG. 1, and the in-vehicle terminal 10 exchanges data with the information center 30 via the communication terminal 20. Send and receive. Data transmission / reception between the in-vehicle terminal 10 and the information center 30 is executed based on TCP / IP. That is, when data is transmitted from the in-vehicle terminal 10 to the information center 30 and the information center 30 correctly receives the data, the information center 30 transmits an acknowledgment to the in-vehicle terminal 10. The in-vehicle terminal 10 can confirm that the data transmitted by itself is correctly received by the information center 30 by receiving the confirmation response. If the information center 30 cannot receive data correctly due to some trouble and the confirmation response is not received within the predetermined time in the in-vehicle terminal 10, the retransmission control unit 14 can obtain the confirmation response to the data output unit 12. Instructs retransmission of the same data as no data.

  In the present embodiment, the following retransmission control is executed when wireless communication between the communication terminal 20 and the information center 30 is interrupted.

  The communication state detection unit 27 of the communication terminal 20 detects the state of wireless communication from radio wave sensitivity or the like. When the communication state detection unit 27 confirms that the wireless communication is stopped (interrupted), the interruption time measuring unit 28 starts counting the wireless communication stop time (interruption time).

  When the wireless communication is stopped, the data transfer from the in-vehicle terminal 10 to the information center 30 is not normally executed, and therefore the confirmation response is not returned to the in-vehicle terminal 10. When the confirmation response is not received within the predetermined time, the interruption time confirmation unit 16 of the in-vehicle terminal 10 reads the wireless communication interruption time counted by the interruption time measurement unit 28 of the communication terminal 20. The retransmission control unit 14 instructs the data output unit 12 to retransmit data based on the interruption time read by the interruption time confirmation unit 16.

  If the confirmation response is not received within a predetermined time, the retransmission control unit 14 does not immediately issue a data retransmission instruction, but issues a retransmission instruction after an elapse of the interruption time after the predetermined time elapses. If a confirmation response is returned due to recovery of wireless communication while waiting for a retransmission instruction for the interruption time, the data output unit 12 outputs the next data without waiting for the interruption time to elapse. May be.

  As described above, as a result of delaying the retransmission control by the wireless communication interruption time, unnecessary retransmission data output from the in-vehicle terminal 10 to the communication terminal 20 is suppressed, and the retransmission data is stacked on the communication terminal 20. You can avoid that.

  FIG. 3 shows a preferred third embodiment of the data communication apparatus according to the present invention, and FIG. 3 is an overall configuration diagram thereof.

  The data communication device 2 shown in FIG. 3 is composed of an in-vehicle terminal 10 and a communication terminal 20 similar to those shown in FIGS. 1 and 2, and the in-vehicle terminal 10 communicates with the information center 30 via the communication terminal 20. Send and receive data with. Data transmission / reception between the in-vehicle terminal 10 and the information center 30 is executed based on TCP / IP. That is, when data is transmitted from the in-vehicle terminal 10 to the information center 30 and the information center 30 correctly receives the data, the information center 30 transmits an acknowledgment to the in-vehicle terminal 10. The in-vehicle terminal 10 can confirm that the data transmitted by itself is correctly received by the information center 30 by receiving the confirmation response. If the information center 30 cannot receive data correctly due to some trouble and the confirmation response is not received within the predetermined time in the in-vehicle terminal 10, the retransmission control unit 14 can obtain the confirmation response to the data output unit 12. Instructs retransmission of the same data as no data.

  In the present embodiment, the following retransmission control is executed when wireless communication between the communication terminal 20 and the information center 30 is interrupted.

  The communication state detection unit 27 of the communication terminal 20 detects the state of wireless communication, that is, the stop (interruption) and restart of wireless communication from the radio wave sensitivity or the like. The communication state notification unit 29 outputs the detection result of the communication state detection unit 27 to the communication state confirmation unit 18 of the in-vehicle terminal 10. Then, the retransmission control unit 14 of the in-vehicle terminal 10 issues a data retransmission instruction to the data output unit 12 based on the wireless state confirmation result acquired by the communication state confirmation unit 18.

  The retransmission control unit 14 continues the retransmission control when the wireless communication is not interrupted. That is, when the confirmation response is not received within the predetermined time, the data output unit 12 is instructed to retransmit the same data as the data for which the confirmation response cannot be obtained. On the other hand, when the wireless communication is interrupted, the retransmission control unit 14 stops the retransmission control. That is, when the communication status confirmation unit 18 confirms the stop of the wireless communication, the retransmission control is stopped and the data retransmission instruction is not performed. Then, when resumption of wireless communication is confirmed, retransmission control is resumed.

  Thus, since retransmission control is not performed while wireless communication is interrupted, unnecessary retransmission data is not output from the in-vehicle terminal 10 to the communication terminal 20 within the interruption time during which wireless communication is interrupted. It is possible to avoid the retransmission data from being stacked on the communication terminal 20.

  The preferred embodiment of the present invention has been described above. As an application example of the present invention, the in-vehicle terminal and the communication terminal are replaced with the host computer and the relay station, respectively, and the host computer performs wireless communication via the relay station. A configuration for performing the above is also conceivable. In other words, the present invention can be applied not only to a device mounted on a mobile body but also to a communication form in which wireless communication is difficult.

1 is an overall configuration diagram of a preferred embodiment 1 of a data communication apparatus according to the present invention. It is a whole block diagram of suitable Embodiment 2 of the data communication apparatus which concerns on this invention. It is a whole block diagram of suitable Embodiment 3 of the data communication apparatus which concerns on this invention.

Explanation of symbols

  10 in-vehicle terminals, 20 communication terminals, 30 information centers.

Claims (7)

A data communication device including an in-vehicle terminal and a communication terminal,
The in-vehicle terminal has data output means for outputting communication data to the communication terminal,
The communication terminal has a transmission means for transmitting a communication signal corresponding to the communication data acquired from the in-vehicle terminal to the reception side device by wireless communication,
When the communication data acquired from the in-vehicle terminal is retransmission data related to already acquired communication data, the transmission means transmits a communication signal corresponding to the acquired communication data and corresponds to the retransmission data. Don't send,
A data communication device. The data communication device according to claim 1,
The communication terminal is
Storage means for storing communication data acquired from the in-vehicle terminal;
The communication data acquired from the in-vehicle terminal and the already acquired communication data stored in the storage means are compared, and the acquired communication data and the already acquired communication data are communication data corresponding to the same content. Data comparison means for determining, in some cases, the acquired communication data as retransmission data;
Further having
A data communication device. A data communication device including an in-vehicle terminal and a communication terminal,
The in-vehicle terminal has data output means for outputting communication data to the communication terminal,
The communication terminal has a transmission means for transmitting a communication signal corresponding to the communication data acquired from the in-vehicle terminal to the reception side device by wireless communication,
The data output means controls the output of the communication data according to the interruption state of the wireless communication;
A data communication device. The data communication device according to claim 3,
The communication terminal further includes interruption time measuring means for measuring the interruption time of the wireless communication,
The in-vehicle terminal further includes an interruption time confirmation unit that confirms the interruption time measured by the interruption time measurement unit.
A data communication device. The data communication device according to claim 4,
The data output means stops outputting the communication data during a stop period according to the interruption time confirmed by the interruption time confirmation means;
A data communication device. The data communication device according to claim 3,
The communication terminal further includes communication state notification means for notifying the in-vehicle terminal of communication state information indicating a state where the wireless communication is being executed or a state where the wireless communication is interrupted.
A data communication device. The data communication device according to claim 6,
The data output means stops outputting the communication data in a state where the wireless communication is interrupted;
A data communication device.

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