JP2009246533A - Communication terminal, communicating method, data communication system, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To confirm delivery of transmission data by suppressing a load increase in a network and a transmitting/receiving terminal. <P>SOLUTION: A delivery confirmation processing portion 14 determines necessity of a delivery confirmation based on retransmission history information 12B of a storing portion 12 before retransmission of data by a communication controller 13, and transmits a delivery confirmation request to a receiving terminal 20 through a communication processor 11 when the necessity of the delivery confirmation is determined. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a data communication technique, and more particularly to a data retransmission control technique for retransmitting data from a transmission terminal to a reception terminal.

In data communication, TCP is widely used as a protocol for guaranteeing data reachability (see, for example, Non-Patent Document 1). In such a protocol, a sequence number is assigned to each packet and transmitted from the transmitting terminal to the receiving terminal. The receiving terminal refers to the sequence number of the received data, adds a sequence number expected to be received next to the confirmation response packet, and transmits it to the transmitting terminal.
Also, in the above-described confirmation response operation, when an acknowledgment is returned for each packet, since the overhead due to the acknowledgment is large, a delayed ACK is proposed in which acknowledgments for a plurality of packets are collectively returned. (For example, refer nonpatent literature 2 etc.).

  In TCP, when an acknowledgment packet is not received for a predetermined time or longer, it is determined that data has been discarded and data is retransmitted. Therefore, even if data is not discarded, the acknowledgment is discarded, and particularly when a large amount of retransmission occurs, a load is placed on the network and transmitting / receiving terminals, and at the same time, communication efficiency decreases.

As a related technique for this, when the data discard is confirmed and data retransmission is performed, before the data retransmission, a probe packet is transmitted from the transmission terminal to the reception terminal, and in response to a response from the reception terminal, There has been proposed a technique for confirming delivery related to data transmitted from a transmitting terminal to a receiving terminal (see, for example, Patent Document 1). Thereby, it is possible to confirm data that does not need to be retransmitted from the transmission terminal before data retransmission, and to prevent redundant retransmission.
JP 2005-173961 A RFC 793, "TRANSMISSION CONTROL PROTOCOL," http://www.ietf.org/rfc/rfc0793.txt, pp.8-9, "2.6 Reliable Communication." RFC1122, "Requirements for Internet Hosts-Communication Layers," http://www.ietf.org/rfc/rfc1122.txt, pp.95-96, "4.2.3.2 When to Send an ACK Segment."

However, in such a related technique, at the time of data retransmission, since the transmission confirmation is performed by always exchanging the probe packet and the response between the transmission terminal and the reception terminal, the overhead due to these delivery confirmation procedures increases, In spite of the occurrence of a communication error, there is a problem that the load on the network and the transmission / reception terminal increases and the communication efficiency decreases.
The present invention is for solving such problems, a communication terminal, a communication method, a data communication system, and a communication terminal capable of confirming delivery of transmission data while suppressing an increase in load on the network and the transmission / reception terminal, and The purpose is to provide a program.

  In order to achieve such an object, the communication terminal according to the present invention performs communication for making a data delivery confirmation request to the receiving terminal before retransmitting the data to the receiving terminal during data communication with the receiving terminal. When making a delivery confirmation request, the terminal determines whether or not delivery confirmation is necessary based on history information regarding data retransmission to the receiving terminal.

  Further, in the communication method according to the present invention, during data communication between the transmission terminal and the reception terminal, the data transmission confirmation from the transmission terminal to the reception terminal is performed before the data is retransmitted from the transmission terminal to the reception terminal. In this communication method, when the transmission terminal makes a delivery confirmation request, it determines whether or not the delivery confirmation is necessary based on the history information regarding the data retransmission to the reception terminal.

  In addition, the data communication system according to the present invention provides a data delivery confirmation from the transmitting terminal to the receiving terminal before data is retransmitted from the transmitting terminal to the receiving terminal during data communication between the transmitting terminal and the receiving terminal. A data communication system that performs the above-described communication terminal is provided as a transmission terminal.

  In addition, when retransmitting data in response to a communication error that occurred during data communication with a receiving terminal, the program according to the present invention is a communication terminal that confirms data delivery to the receiving terminal before the data is retransmitted. A computer is caused to execute processing of a transmitting terminal in the communication method.

  According to the present invention, since delivery confirmation is not necessarily performed at the time of data retransmission, overhead due to these delivery confirmation procedures can be suppressed, and transmission data can be transmitted while suppressing an increase in load on the network and transmission / reception terminals. Delivery confirmation can be made.

Next, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
First, a data communication system according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing a configuration of a data communication system according to the first embodiment of the present invention.
This data communication system includes a transmission terminal (communication terminal) 10 and a reception terminal 20 connected via a communication network 30.
The transmission terminal 10 and the reception terminal 20 are configured from an information processing apparatus having a data communication function, such as a personal computer, a server, a mobile phone terminal, or a PDA.

The transmitting terminal 10 has a function of making a data delivery confirmation request to the receiving terminal 20 before retransmitting data to the receiving terminal 20 during data communication with the receiving terminal 20.
In the present embodiment, when a transmission confirmation request is made in the transmission terminal 10, it is determined whether or not a delivery confirmation is necessary based on history information regarding data retransmission.

The transmission terminal (communication terminal) 10 includes a communication processing unit 11, a storage unit 12, a communication control unit 13, and a delivery confirmation processing unit 14 as main functional units. Connected for data communication.
The communication processing unit 11 includes a dedicated communication circuit, and has a function of transmitting and receiving data between the receiving terminals 20 via the communication network 30.
The storage unit 12 includes a storage device such as a hard disk or a memory, and has a function of storing various information related to data communication with the receiving terminal 20 such as transmission data 12A and retransmission history information 12B.

The communication control unit 13 functions to form a channel for data communication with the receiving terminal 20 via the communication processing unit 11 based on a communication protocol such as TCP or UDP, and transmits / receives data via this channel. A function for retransmitting data when a communication error occurs, and a function for recording retransmission history information 12B regarding data retransmission.
The delivery confirmation processing unit 14 has a function of determining whether or not delivery confirmation is necessary based on the retransmission history information 12B of the storage unit 12 before retransmitting data in the communication control unit 13, and when it is determined that delivery confirmation is necessary. And a function of transmitting a delivery confirmation request to the receiving terminal 20 via the communication processing unit 11.

  The communication control unit 13 and the delivery confirmation processing unit 14 include an arithmetic processing unit having a CPU and its peripheral circuits, and read the program stored in advance in the storage unit 12 and execute it in the arithmetic processing unit. Various functions are realized.

Next, the retransmission history information 12B will be described with reference to FIG. FIG. 2 is a configuration example of retransmission history information.
The retransmission history information 12B is history information regarding data retransmission, and is recorded by the communication control unit 13 for each data retransmission process in data communication with the receiving terminal 20. Here, the round number subjected to the data retransmission processing and the amount of retransmission data are recorded as a set for each data retransmission processing and stored in the storage unit 12 as retransmission history information 12B.

  As shown in FIG. 4 to be described later, the round is a process of transmitting transmission data (DT) from the transmission terminal 10 to the reception terminal 20, and a reception confirmation response (ACK) from the reception terminal 20 to the transmission terminal 10 in response thereto. Is a series of data transfer procedures composed of a pair with the process of returning the data. Even when a plurality of data is transmitted in a batch and one reception confirmation response is returned, the data is counted as one round.

  The delivery confirmation processing unit 14 reads the retransmission history information 12B from the storage unit 12, and calculates a determination target value and a threshold value used for determining whether or not delivery confirmation is necessary. The determination target value is an evaluation value indicating the latest data retransmission status, and is calculated from the data belonging to the target period assigned at a time close to the determination of necessity of delivery confirmation in the retransmission history information 12B. On the other hand, the threshold value is a reference value for determining the determination target value, and is calculated from data belonging to a reference period including a period before the target period in the retransmission history information 12B. At this time, part or all of the target period may be included in the reference period.

  These target period and reference period are set in advance based on the number of rounds of the data transmission procedure. As the determination target value and the threshold value, an average value of retransmission data amounts in the target period and the reference period, that is, an average retransmission data amount per round is used.

In the example of FIG. 2, the past 10 rounds are assigned as the target period from the time of determining whether delivery confirmation is necessary, and the last 100 rounds are assigned as the reference period from the target period. These round numbers are merely examples, and are not limited to this example.
As shown in FIG. 2, when the target period and the reference period are defined by the number of rounds, the determination target value is the average value of the retransmission data amount for each round in the target period, that is, the average retransmission data amount per round in the target period. Can be calculated and used. As for the threshold value, an average value of the retransmission data amount per round in the reference period, that is, an average retransmission data amount per round in the reference period may be calculated and used. When the target period and the reference period are defined by the number of rounds, the amount of data remaining in the retransmission buffer 13B when determining whether delivery confirmation is necessary may be used as the determination target value.

Further, as the target period and the reference period, a time length may be used instead of the number of rounds. In this case, the retransmission time may be recorded in the retransmission history information 12B instead of the round number.
When the target period or reference period is specified by the length of time, for the judgment target value, the average value of the amount of retransmission data for each unit time in the target period, that is, the average amount of retransmission data per unit time in the target period is calculated. Can be used. As for the threshold value, an average value of retransmission data amounts per unit time in the reference period, that is, an average retransmission data amount per unit time in the reference period may be calculated and used.

  As for the threshold value, the maximum amount of retransmission data may be used instead of the average amount of retransmission data. For example, when the target period and the reference period are defined by the number of rounds, the maximum value of the retransmission data amount for each round in the reference period, that is, the maximum retransmission data amount per round in the reference period may be calculated and used. When the target period and reference period are specified by time length, the maximum retransmission data amount per unit time in the reference period, that is, the maximum retransmission data amount per unit time in the reference period is calculated and used as a threshold value. That's fine.

  Further, as the threshold value, a fixed value calculated based on a ratio of data retransmission without confirming delivery to the transmitted data amount, that is, an allowable data retransmission rate may be used. For example, when the amount of retransmission data is less than 80% of the unit data transmission amount transmitted in one round or unit time, data retransmission is performed without confirming delivery before data retransmission, and the amount of retransmission data is equal to the unit data transmission amount. In the case of 80% or more, the allowable data retransmission rate for the data communication is represented as 80%. Therefore, for example, when data is transmitted by 10 KB per round, 8 KB corresponding to 80% of 10 KB, which is the unit data transmission amount per round, may be set as the threshold value.

[Operation of First Embodiment]
Next, the operation of the transmission terminal (communication terminal) according to the first embodiment of the present invention will be described with reference to FIG. FIG. 3 is a flowchart showing a delivery confirmation process of the transmission terminal according to the first embodiment of the present invention.

  The communication control unit 13 forms one channel on one session formed for data communication with the receiving terminal 20, and a part of the data (DT) from the transmission data 12A of the storage unit 12 Are sequentially read out and transmitted to the receiving terminal 20 through the channel. In response to this, a reception confirmation response (ACK) for the transmission data is received from the receiving terminal 20, and data is retransmitted according to this content or when the reception confirmation response is discarded. These data transmission processes are performed based on a general communication protocol.

Each time the communication control unit 13 transmits data (DT) in the communication control unit 13, the delivery confirmation processing unit 14 confirms the arrival of the delivery confirmation timing based on the elapsed time from the data transmission, and responds to the arrival of the delivery confirmation timing. Then, the delivery confirmation process of FIG. 3 is executed.
First, the delivery confirmation processing unit 14 calculates the above-described determination target value based on the retransmission history information 12B in the storage unit 12 (step 100). In this case, if the threshold value needs to be updated, a new threshold value may be calculated in this step.

Next, the delivery confirmation processing unit 14 determines whether or not delivery confirmation is necessary by comparing the determination target value with a threshold value (step 101). Here, when the determination target value is equal to or smaller than the threshold value, it is determined that the delivery confirmation is unnecessary (step 102: NO), and the series of processes is terminated.
On the other hand, when the determination target value exceeds the threshold value, it is determined that delivery confirmation is necessary (step 102: YES), and the delivery confirmation processing unit 14 issues a delivery confirmation request regarding the data (DT) transmitted by the data transmission. Then, the data is transmitted from the communication processing unit 11 to the receiving terminal 20 (step 103).

Thereafter, a delivery confirmation response to the delivery confirmation request is received from the receiving terminal 20 via the communication processing unit 11 (step 104).
If undelivered data is notified by this delivery confirmation response, the communication control unit 13 retransmits the undelivered data from the communication processing unit 11 to the receiving terminal 20 (step 105). Thereafter, the communication control unit 13 records the history regarding the retransmitted data in the retransmission history information 12B of the storage unit 12 (step 106), and ends the series of processes.

  Next, with reference to FIG. 4, an operation example of the transmission terminal according to the first embodiment of the present invention will be described. FIG. 4 is a sequence diagram illustrating an operation example of the transmission terminal according to the first embodiment of the present invention.

First, at time T1, the transmission terminal 10 transmits data (DT) of sequence numbers SN1 to SN3 all at once, and starts a delivery confirmation timer for timing the delivery confirmation timing in accordance with this transmission.
At the subsequent time T2, a receipt confirmation response (ACK) for the data is received, and the delivery confirmation timer is stopped because the delivery confirmation is no longer necessary. This reception confirmation response describes SN3 having the largest sequence number among the received data, and the transmission terminal 10 confirms that all the data of SN1 to SN3 has been received at the reception terminal 20.

At the subsequent time T3, the transmission terminal 10 transmits the data of the sequence numbers SN4 to SN6 all at once, and starts a delivery confirmation timer for measuring the delivery confirmation timing in accordance with this transmission.
Here, when the reception confirmation response with respect to the said data is abandoned on the way, the delivery confirmation timer expires at the time T4 after that. Thereby, the delivery confirmation timing arrives, and the transmission confirmation process of FIG.

If it is determined that delivery confirmation is required, the transmission terminal 10 transmits a delivery confirmation request to the reception terminal 20 at time T5, and receives a delivery confirmation response from the reception terminal 20 corresponding thereto at time T6. To do.
This delivery confirmation response describes SN5 having the largest sequence number among the received data, and the transmission terminal 10 confirms that the reception terminal 20 has not received the data of SN6 among the above data. .

In response to this, the transmission terminal 10 retransmits the data of the sequence number SN6 to the reception terminal 20 and activates a delivery confirmation timer at time T7. At subsequent time T8, a reception confirmation response to the data is received, and the delivery confirmation timer is stopped. The transmission terminal 10 confirms reception of the data of the sequence number SN6 by this reception confirmation response.
On the other hand, in the delivery confirmation process, when it is determined that the delivery confirmation is unnecessary, the transmission terminal 10 retransmits the data of the sequence numbers SN4 to SN6 at a time according to the elapsed time from the time T3, for example. Thereafter, the above-described processing is repeatedly executed.

[Effect of the first embodiment]
As described above, according to the present embodiment, when a transmission confirmation request is made from the transmission terminal 10 to the reception terminal 20, the necessity of delivery confirmation is determined based on the retransmission history information 12B regarding data retransmission.
For this reason, delivery confirmation is not necessarily performed at the time of data retransmission, so overhead due to these delivery confirmation procedures can be suppressed, and transmission confirmation of transmission data can be performed while suppressing an increase in load on the network and transmitting / receiving terminals. It can be carried out.

  Further, in the present embodiment, a statistic regarding the data retransmission amount in an arbitrary target period is calculated as a determination target value from the history information, and a delivery confirmation request is made when the determination target value exceeds a predetermined threshold value. I have to. As a result, the delivery confirmation request is made only when the amount of data retransmission tends to increase and the deterioration of the data communication status is estimated. For this reason, the increasing amount of data retransmission can be reduced by this delivery confirmation, further deterioration of the data communication status can be suppressed, and early improvement of the data communication status can be led.

In the present embodiment, the amount of data retransmission per round operation consisting of a set of data transmission performed between the transmission terminal and the reception terminal and a reception confirmation notification corresponding thereto in the target period is determined as a determination target value. Therefore, it is possible to confirm in detail the change in the data retransmission status according to the round, and to more accurately determine whether or not delivery confirmation is necessary.
In the present embodiment, since the average data retransmission amount per unit time in the target period is calculated as the determination target value, it is possible to confirm in detail the change in the data retransmission status according to the communication time, It becomes possible to determine the necessity of delivery confirmation more accurately.

In the present embodiment, the statistics regarding the data retransmission amount in the reference period including the period past the target period are calculated as threshold values from the history information, so that the change in the data retransmission status is confirmed in detail. This makes it possible to more accurately determine whether or not delivery confirmation is necessary.
In the present embodiment, the maximum data retransmission amount generated in any unit time in the reference period may be calculated as a threshold value, and the threshold value can be calculated with extremely simple processing. Become.

[Second Embodiment]
Next, a transmission terminal (communication terminal) according to the second embodiment of the present invention will be described with reference to FIG. FIG. 5 is a block diagram showing a configuration of a transmission terminal according to the second embodiment of the present invention.
In the present embodiment, specific configurations of the communication processing unit 11, the communication control unit 13, and the delivery confirmation processing unit 14 of the transmission terminal 10 will be described.

The communication processing unit 11 includes a communication interface unit (hereinafter referred to as a communication I / F unit) 11A, a data transmission unit 11B, and a data reception unit 11C as main functional units.
The communication I / F unit 11A has a function of transmitting various data output from the data transmission unit 11B to the communication network 30 side, and a function of outputting various data received from the communication network 30 to the data reception unit 11C. ing.

The data transmission unit 11B has a function of transmitting various data such as data read from the communication control unit 13 and a delivery confirmation request output from the delivery confirmation processing unit 14 from the communication I / F unit 11A.
The data receiving unit 11C has a function of outputting various data such as a reception confirmation response and a delivery confirmation response from the receiving terminal 20 received via the communication I / F unit 11A to the communication control unit 13 and the delivery confirmation processing unit 14. Have.

The communication control unit 13 includes a data input / output unit 13A, a transmission buffer 13B, a retransmission buffer 13C, a retransmission control unit 13D, and an acknowledgment processing unit 13E as main functional units.
The data input / output unit 13A has a function of reading data to be transmitted from the transmission data 12A in the storage unit 12 and storing it in the transmission buffer 13B at the time of data transmission.

The retransmission control unit 13D measures the elapsed time from the data transmission with the retransmission timer and monitors the retransmission timing, and instructs the data transmission unit 11B to retransmit the data stored in the retransmission buffer when the retransmission timing arrives. The function, the function of instructing the data transmission unit 11B to retransmit the unreceived data confirmed by the reception confirmation response or the delivery confirmation response from the reception terminal 20, and the history regarding the data retransmission are recorded in the retransmission history information 12B of the storage unit 12. It has a function.
The confirmation response processing unit 13E has a function of receiving a reception confirmation response returned from the receiving terminal 20 after data transmission, and deleting the reception confirmed data from the retransmission buffer 13C.

The delivery confirmation processing unit 14 includes a delivery confirmation unit 14A and a threshold value determination unit 14B as main functional units.
The delivery confirmation unit 14A measures the elapsed time from data transmission with a retransmission timer, monitors the arrival of the delivery confirmation timing, and instructs the data transmission unit 11B to transmit a delivery confirmation request in response to the arrival of the delivery confirmation timing have.
The threshold value determination unit 14B has a function of calculating a threshold value based on the retransmission history information 12B in the storage unit 12 in accordance with the data retransmission in the retransmission control unit 13D.

[Operation of Second Embodiment]
Next, with reference to FIGS. 6-10, operation | movement of the transmission terminal (communication terminal) concerning the 2nd Embodiment of this invention is demonstrated. FIG. 6 is a sequence diagram showing a data transmission operation of the transmission terminal according to the second embodiment of the present invention. FIG. 7 is a sequence diagram showing the confirmation response processing operation of the transmitting terminal according to the second embodiment of the present invention. FIG. 8 is a sequence diagram showing a delivery confirmation transmission operation of the transmission terminal according to the second embodiment of the present invention. FIG. 9 is a sequence diagram showing a data retransmission operation of the transmission terminal according to the second embodiment of the present invention.

First, the data transmission operation at the transmission terminal 10 will be described with reference to FIG.
When data (DT) to be transmitted is stored in the transmission buffer 13B by the data input / output unit 13A on condition that the transmission buffer 13B is empty, the data transmission unit 11B reads the data from the transmission buffer 13B. (Step 200), data is transmitted from the communication I / F unit 11A to the receiving terminal 20 (Step 201).

Thereafter, the data transmission unit 11B notifies the retransmission control unit 13D and the delivery confirmation unit 14A of the transmission status related to the data transmission (step 202). Further, the data transmission unit 11B stores the data in the transmission buffer 13B transmitted by the data transmission in the retransmission buffer 13C (step 203), and deletes the data in the transmission buffer 13B.
The retransmission control unit 13D activates a retransmission timer in response to the transmission status notification from the data transmission unit 11B (step 205). Also, the delivery confirmation unit 14A activates a delivery confirmation timer in response to the transmission status notification from the data transmission unit 11B (step 206).
In this way, a series of data transmission operations is completed.

Next, with reference to FIG. 7, the reception confirmation process at the transmission terminal 10 will be described.
When the data reception unit 11C receives a reception confirmation response (ACK) from the reception terminal 20 via the communication I / F unit 11A (step 300), the data reception unit 11C confirms the reception status related to the reception confirmation response by the confirmation response processing unit 13E. The control unit 13D and the delivery confirmation unit 14A are notified (step 301).
In response to the reception status notification from the data receiving unit 11C, the confirmation response processing unit 13E deletes the data that has been confirmed to be received from the data in the retransmission buffer 13C (step 302). Further, the retransmission control unit 13D stops the retransmission timer in response to the reception status notification from the data receiving unit 11C (step 303). Further, the delivery confirmation unit 14A stops the delivery confirmation timer in response to the reception status notification from the data reception unit 11C (step 304).

The retransmission control unit 13D checks the retransmission buffer 13C after stopping the retransmission timer (step 310), and if undelivered data remains (step 311), instructs the data transmission unit 11B to retransmit the undelivered data. (Step 312).
The data transmission unit 11B reads data from the retransmission buffer 13C in response to a retransmission instruction from the retransmission control unit 13D (step 320), and retransmits the data from the communication I / F unit 11A to the receiving terminal 20 (step 321). Then, the transmission status regarding this data retransmission is notified to the retransmission control unit 13D and the delivery confirmation unit 14A (step 322).

The retransmission control unit 13D activates a retransmission timer in response to the transmission status notification from the data transmission unit 11B (step 323). Further, the history regarding this data retransmission is recorded in the retransmission history information 12B of the storage unit 12 (step 324), and the threshold value determination unit 14B is instructed to update the threshold value (step 325). In response, threshold determination unit 14B reads retransmission history information 12B and calculates a new threshold (step 326).
Also, the delivery confirmation unit 14A activates a delivery confirmation timer in response to the transmission status notification from the data transmission unit 11B (step 327).
In this way, a series of reception confirmation operations are completed.

Next, the delivery confirmation transmission operation at the transmission terminal 10 will be described with reference to FIG.
When the delivery confirmation timer expires (step 400), the delivery confirmation unit 14A reads the retransmission history information 12B from the storage unit 12 (step 401), and calculates a determination target value (step 402). Thereafter, the threshold value is acquired from the threshold value determination unit 14B (step 403), and the determination target value is compared with the threshold value (step 404).
Here, when the determination target value exceeds the threshold value (step 405), the delivery confirmation unit 14A instructs the data transmission unit 11B to transmit a delivery confirmation request (step 406).

In response to the delivery confirmation request transmission instruction from the delivery confirmation unit 14A, the data transmission unit 11B confirms the data in the retransmission buffer 13C (step 407), and receives the delivery confirmation request regarding this data from the communication I / F unit 11A. It transmits to the terminal 20 (step 408). Then, the delivery confirmation unit 14A is notified of the transmission status regarding the transmission of the delivery confirmation request (step 409).
The delivery confirmation unit 14A activates a delivery confirmation timer in response to the transmission status notification from the data transmission unit 11B (step 410).
In this way, a series of delivery confirmation transmission operations are completed.

  As a specific example of the delivery confirmation request, the data having the largest sequence number among the data in the retransmission buffer 13C may be retransmitted. As a result, the reception terminal 20 confirms the reception status at its own terminal and notifies the transmission terminal 10 by a reception confirmation response in the same process as when receiving normal data. Further, the transmission terminal 10 can cope with the same processing operation as that at the time of normal data transmission, for example, the above-described confirmation response processing operation of FIG. 7 according to the reception confirmation response from the reception terminal 20. Therefore, the receiving terminal 20 can respond to the delivery confirmation request without adding a new process. In addition, the transmission terminal 10 can cope with the delivery confirmation response without separately providing a new process.

  Further, when a special message is used as the delivery confirmation request and the delivery confirmation response, the receiving terminal 20 needs to analyze the message, but the delivery confirmation response process after the analysis process is as follows. This is the same as the reception confirmation response process, and if this process is used, it is also possible to reduce the additional change of the process. In addition, in the transmission terminal 10, processing for analyzing the delivery confirmation response from the reception terminal 20 is required. As the delivery confirmation response processing after the analysis processing, for example, the above-described confirmation response processing operation in FIG. If this processing is used, it is possible to reduce the amount of additional processing changes.

Next, with reference to FIG. 9, the data retransmission operation at the transmission terminal 10 will be described.
When the retransmission timer expires (step 500), the retransmission control unit 13D instructs the data transmission unit 11B to retransmit undelivered data remaining in the retransmission buffer 13C (step 501).
In response to the retransmission instruction from the retransmission control unit 13D, the data transmission unit 11B reads data from the retransmission buffer 13C (step 510), and retransmits the data from the communication I / F unit 11A to the receiving terminal 20 (step 511). Then, the transmission status relating to the data retransmission is notified to the retransmission control unit 13D and the delivery confirmation unit 14A (step 512).

The retransmission control unit 13D activates a retransmission timer in response to the transmission status notification from the data transmission unit 11B (step 513). Further, the history regarding the data retransmission is recorded in the retransmission history information 12B of the storage unit 12 (step 514), and the threshold value determination unit 14B is instructed to update the threshold value (step 515). In response to this, the threshold value determination unit 14B reads the retransmission history information 12B and calculates a new threshold value (step 516).
In addition, the delivery confirmation unit 14A activates a delivery confirmation timer in response to the transmission status notification from the data transmission unit 11B (step 517).
In this way, a series of reception confirmation operations are completed.

[Third Embodiment]
Next, a data communication system according to the third embodiment of the present invention will be described with reference to FIG. FIG. 10 is a block diagram showing a data communication system according to the third embodiment of the present invention.

  In the first embodiment, the case where data communication is performed by forming one channel on one session between the transmission terminal 10 and the reception terminal 20 has been described as an example. In the present embodiment, a case where a single session is formed between the transmission terminal 10 and the reception terminal 20, a plurality of channels are formed on the session, and data communication is performed using these channels in parallel will be described. To do.

The transmission terminal 10 according to the present embodiment includes a communication processing unit 11, a storage unit 12, a plurality of communication control units 13, and a delivery confirmation processing unit 14 as main functional units.
The communication processing unit 11 includes a dedicated communication circuit, and has a function of transmitting and receiving data between the receiving terminals 20 via the communication network 30.
The storage unit 12 includes a storage device such as a hard disk or a memory, and has a function of storing various information related to data communication with the receiving terminal 20 such as transmission data 12A and retransmission history information 12B.

The communication control unit 13 functions to form a channel for data communication with the receiving terminal 20 via the communication processing unit 11 based on a communication protocol such as UDP or TCP, and transmits / receives data via this channel. A function for retransmitting data when a communication error occurs, and a function for recording retransmission history information 12B regarding data retransmission.
The delivery confirmation processing unit 14 has a function of determining whether or not delivery confirmation is necessary based on the retransmission history information 12B of the storage unit 12 before retransmitting data in the communication control unit 13, and when it is determined that delivery confirmation is necessary. And a function of transmitting a delivery confirmation request to the receiving terminal 20 via the communication processing unit 11.

  The communication control unit 13 and the delivery confirmation processing unit 14 include an arithmetic processing unit having a CPU and its peripheral circuits, and read the program stored in advance in the storage unit 12 and execute it in the arithmetic processing unit. Various functions are realized.

In this embodiment, the communication control part 13 is provided in parallel for every channel formed between the receiving terminals 20, and these communication control parts 13 are about data communication using one corresponding channel. Perform communication control.
Moreover, the delivery confirmation process part 14 is provided in common with each channel, and performs delivery confirmation to the receiving terminal 20 according to the data transmission condition of each channel.

Next, the retransmission history information 12B will be described with reference to FIG. FIG. 11 is another configuration example of retransmission history information.
The retransmission history information 12B is history information regarding data retransmission, and is recorded by each communication control unit 13 for each data retransmission process in data communication with the receiving terminal 20. Here, the round number subjected to the data retransmission process is recorded for each data retransmission process and stored in the storage unit 12 as retransmission history information 12B. At this time, the retransmission history is recorded in the retransmission history information 12B from each communication control unit 13 in common regardless of the channel.

  The delivery confirmation processing unit 14 reads the retransmission history information 12B from the storage unit 12, and calculates a determination target value and a threshold value used for determining whether or not delivery confirmation is necessary. The determination target value is an evaluation value indicating the latest data retransmission status, and is calculated from the data belonging to the target period assigned at a time close to the determination of necessity of delivery confirmation in the retransmission history information 12B. On the other hand, the threshold value is a reference value for determining the determination target value, and is calculated from data belonging to a reference period including a period before the target period in the retransmission history information 12B. At this time, part or all of the target period may be included in the reference period.

These target period and reference period are set in advance based on the number of rounds of the data transmission procedure. For the determination target value and the threshold value, the average value of the number of retransmission channels in the target period or the reference period, that is, the number of retransmission channels per round is used.
At this time, regarding the number of retransmission channels, the number of channels in which data retransmission occurred in the target period and the reference period may be counted, but for example, the number of channels whose average retransmission data amount for several rounds exceeds a predetermined value is counted. As a result, it is possible to exclude sudden data retransmission, and more stable delivery confirmation necessity determination can be realized. In addition, the number of retransmission channels may be counted only for the channels that are connected at the time of determining whether or not delivery confirmation is necessary. This makes it possible to obtain the number of retransmission channels according to the current communication status, and more accurate delivery. Confirmation necessity determination can be realized.

  In the example of FIG. 2, the past 10 rounds are assigned as the target period from the time of determining whether delivery confirmation is necessary, and the last 100 rounds are assigned as the reference period from the target period. Therefore, the determination target value is calculated from the average value of the number of retransmission channels for the past 10 rounds from the time of determining whether delivery confirmation is necessary, and the threshold value is calculated from the average value of the number of retransmission channels for the past 100 rounds from the target period. Has been. These round numbers are merely examples, and are not limited to these numbers.

Note that, as the target period and the reference period, a time length may be used instead of the number of rounds. In this case, the retransmission time may be recorded in the retransmission history information 12B instead of the round number. As a result, the number of retransmission channels per unit time is used as the determination target value and the threshold value.
For the determination target value and threshold value, the maximum number of retransmission channels in the target period or reference period may be used instead of the average number of retransmission channels. A fixed value may be used for the threshold value.

  In addition, as a channel for exchanging an acknowledgment request and a delivery confirmation response, any channel used for data transmission may be used, and a delivery confirmation channel provided separately from data transmission is used. May be.

  In the present embodiment, the configuration of the retransmission history information 12B in the transmission terminal 10 described above and the determination target value and threshold value calculation method in the delivery confirmation processing unit 14 are different. This is the same as the embodiment, and detailed description thereof is omitted here.

[Operation of Third Embodiment]
Next, the operation of the transmission terminal (communication terminal) according to the third embodiment of the present invention will be described.
The delivery confirmation process of the transmission terminal according to the present embodiment is almost the same as that in FIG. Here, with reference to FIG. 3, the delivery confirmation process of the transmission terminal 10 is demonstrated.

Each communication control unit 13 forms a corresponding channel on one session formed for data communication with the receiving terminal 20, and a part of the data from the transmission data 12A of the storage unit 12 (DT) is sequentially read and transmitted to the receiving terminal 20 through the channel.
Each communication control unit 13 receives a reception confirmation response (ACK) for the transmission data from the reception terminal 20 and retransmits the data according to this content or when the reception confirmation response is discarded. These data transmission processes are performed based on a general communication protocol.

Each time each communication control unit 13 transmits data (DT), the delivery confirmation processing unit 14 confirms the arrival of the delivery confirmation timing based on the elapsed time from the data transmission and the like. In response, the delivery confirmation process of FIG. 3 is executed.
First, the delivery confirmation processing unit 14 calculates the above-described determination target value based on the retransmission history information 12B in the storage unit 12 (step 100). In this case, if the threshold value needs to be updated, a new threshold value may be calculated in this step.

Next, the delivery confirmation processing unit 14 determines whether or not delivery confirmation is necessary by comparing the determination target value with a threshold value (step 101). Here, when the determination target value is equal to or smaller than the threshold value, it is determined that the delivery confirmation is unnecessary (step 102: NO), and the series of processes is terminated.
On the other hand, when the determination target value exceeds the threshold value, it is determined that delivery confirmation is necessary (step 102: YES), and the delivery confirmation processing unit 14 issues a delivery confirmation request regarding the data (DT) transmitted by the data transmission. Then, the data is transmitted from the communication processing unit 11 to the receiving terminal 20 (step 103).

Thereafter, a delivery confirmation response to the delivery confirmation request is received from the receiving terminal 20 via the communication processing unit 11 (step 104).
Here, when undelivered data is notified by this delivery confirmation response, the communication control unit 13 corresponding to these undelivered data retransmits the undelivered data from the communication processing unit 11 to the receiving terminal 20 (step 105). ). Thereafter, the communication control unit 13 records the history regarding the retransmitted data in the retransmission history information 12B of the storage unit 12 (step 106), and ends the series of processes.

[Effect of the third embodiment]
As described above, in this embodiment, the number of retransmission channels in which data retransmission has occurred in each channel in an arbitrary target period is calculated from the history information as a determination target value, and this determination target value exceeds a predetermined threshold value. When the data transmission is performed using multiple channels connected between the transmitting terminal and the receiving terminal in parallel, the data retransmission status in each channel is comprehensively Therefore, it is possible to determine whether or not delivery confirmation is necessary.

In this embodiment, since the average number of retransmission channels per unit time in the target period is calculated as the determination target value, the change in data retransmission status according to the communication time in each channel is detailed and comprehensive. It is possible to confirm, and it is possible to more accurately determine whether or not delivery confirmation is necessary.
In the present embodiment, the maximum number of retransmission channels generated in any unit time in the reference period may be calculated as a threshold, and the threshold can be calculated with extremely simple processing. Become.

  In this embodiment, for each data retransmission in each channel, the retransmission data amount is recorded in the retransmission history information 12B, and the average retransmission data amount per unit time in the target period for all channels is determined as a determination target. It may be calculated as a value, and the change of the data retransmission status in each channel can be confirmed in detail and comprehensively, and the necessity of delivery confirmation can be determined more accurately.

[Extended embodiment]
The above embodiments can be applied not only to TCP but also to other communication protocols such as UDP. In particular, for a communication protocol in which the reception confirmation response function is not stipulated as a standard specification such as UDP, a reception confirmation response function equivalent to TCP may be added, for example.
In each of the embodiments, the case where the sequence number indicating the last data of the data that has been continuously confirmed from the beginning by the receiving terminal as a reception confirmation response (ACK) has been described as an example. The present invention can also be applied in the same manner as described above when using a sequence number that can be received (SACK) among data that has been confirmed to be received by the terminal.

  Moreover, although each embodiment demonstrated as an example the case where a delivery confirmation necessity is determined at the time of predetermined time progress from data transmission, it is not limited to this. For example, the necessity of delivery confirmation may be determined in a predetermined cycle timed by the delivery confirmation processing unit 14 without synchronizing the delivery confirmation necessity determination process with the data transmission operation. Further, when the retransmission timer in the communication control unit 13 times out, the delivery confirmation processing unit 14 determines whether or not the delivery confirmation is necessary, and when the delivery confirmation is necessary, the delivery confirmation is performed with the receiving terminal 20. Thereafter, data retransmission may be performed by the communication control unit 13 as necessary, and when the delivery confirmation is unnecessary, the data retransmission may be performed immediately by the communication control unit 13.

  In each embodiment, the case where the necessity of delivery confirmation is determined according to the data retransmission status in the session and channel used for data communication between the transmission terminal 10 and the reception terminal 20 has been described. When different sessions are formed between the terminal 10 and the receiving terminal 20, the necessity of delivery confirmation may be determined according to the data retransmission status in such different sessions.

  In each embodiment, the case where the average retransmission data amount or the average number of retransmission channels is used as the determination target value has been described as an example. However, the present invention is not limited to this, and other indicators indicating the data retransmission status are used. It may be used as a determination target value. For example, the ratio of the retransmission data amount to the transmission data amount transmitted from the transmission terminal 10 to the reception terminal 20, that is, the transmission data loss rate may be used as the determination target value.

It is a block diagram which shows the structure of the data communication system concerning the 1st Embodiment of this invention. It is an example of a structure of resending log | history information. It is a flowchart which shows the delivery confirmation process of the transmission terminal concerning the 1st Embodiment of this invention. It is a sequence diagram which shows the operation example of the transmission terminal concerning the 1st Embodiment of this invention. It is a block diagram which shows the structure of the transmission terminal concerning the 2nd Embodiment of this invention. It is a sequence diagram which shows the data transmission operation | movement of the communication terminal concerning the 2nd Embodiment of this invention. It is a sequence diagram which shows the confirmation response process operation | movement of the communication terminal concerning the 2nd Embodiment of this invention. It is a sequence diagram which shows the delivery confirmation transmission operation | movement of the communication terminal concerning the 2nd Embodiment of this invention. It is a sequence diagram which shows the data resending operation | movement of the communication terminal concerning the 2nd Embodiment of this invention. It is a block diagram which shows the data communication system concerning the 3rd Embodiment of this invention. 10 is another configuration example of retransmission history information.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Transmission terminal (communication terminal), 11 ... Communication processing part, 11A ... Communication I / F part, 11B ... Data transmission part, 11C ... Data reception part, 12 ... Storage part, 12A ... Transmission data, 12B ... Retransmission history information , 13 ... Communication control unit, 13A ... Data input / output unit, 13B ... Transmission buffer, 13C ... Retransmission buffer, 13D ... Retransmission control unit, 13E ... Confirmation response processing unit, 14 ... Delivery confirmation processing unit, 14A ... Delivery confirmation unit, 14B: Threshold value determination unit, 20: Receiving terminal, 30 ... Communication network.

Claims (24)

A communication terminal that performs a data delivery confirmation request to the receiving terminal before retransmitting the data to the receiving terminal during data communication with the receiving terminal;
A communication terminal that determines whether or not a delivery confirmation is necessary based on history information regarding data retransmission to the receiving terminal when the delivery confirmation request is made. The communication terminal according to claim 1,
A statistic regarding a data retransmission amount in an arbitrary target period is calculated as the determination target value from the history information, and the delivery confirmation request is performed when the determination target value exceeds a predetermined threshold value. Communication terminal. The communication terminal according to claim 2,
A data retransmission amount per round operation consisting of a set of data transmission performed between the transmission terminal and the reception terminal and a reception confirmation notification corresponding thereto in the target period is calculated as the determination target value. A communication terminal characterized by that. The communication terminal according to claim 2,
A communication terminal that calculates a data retransmission amount per unit time in the target period as the determination target value. The communication terminal according to claim 2,
A communication terminal characterized in that a statistic relating to a data retransmission amount in a reference period including a period before the target period is calculated as the threshold value from the history information. The communication terminal according to claim 5,
A communication terminal characterized in that a maximum data retransmission amount generated in an arbitrary unit time in the reference period is calculated as the threshold value. The communication terminal according to claim 5,
Of the reference period, the maximum data retransmission amount generated per arbitrary round operation, which consists of a set of data transmission performed between the transmitting terminal and the receiving terminal and a reception confirmation notification corresponding thereto. The communication terminal is calculated as the threshold value. The communication terminal according to claim 1,
When data communication is performed using a plurality of channels connected to the receiving terminal in parallel, the number of retransmission channels in which data retransmission has occurred among these channels in an arbitrary target period is calculated from the history information. A communication terminal that is calculated as a determination target value and performs the delivery confirmation when the determination target value exceeds a predetermined threshold value. The communication terminal according to claim 8,
A communication terminal characterized in that the number of retransmission channels in a reference period including a period before the target period is calculated as the threshold value from the history information. The communication terminal according to claim 1,
When data communication is performed using a plurality of channels connected to the receiving terminal in parallel, a statistic regarding the amount of data retransmission on these channels in an arbitrary target period is determined from the history information as the determination target. A communication terminal that is calculated as a value and transmits the delivery confirmation when the determination target value exceeds a predetermined threshold value. The communication terminal according to claim 10,
A communication terminal that calculates, as the threshold value, from the history information, a statistic regarding a data retransmission amount in these channels in a reference period including a period before the target period. A communication method for performing data delivery confirmation from a transmission terminal to a reception terminal before retransmitting data from the transmission terminal to the reception terminal during data communication between the transmission terminal and the reception terminal,
When the transmission terminal makes the delivery confirmation request, the communication method determines whether or not delivery confirmation is necessary based on history information regarding data retransmission to the reception terminal. The communication method according to claim 12,
The transmission terminal calculates a statistic regarding the data retransmission amount in an arbitrary target period as the determination target value from the history information, and makes the delivery confirmation request when the determination target value exceeds a predetermined threshold value A communication method characterized by the above. The communication method according to claim 13,
The transmission terminal determines the data retransmission amount per round operation consisting of a set of data transmission performed between the transmission terminal and the reception terminal and a reception confirmation notification corresponding thereto in the target period. A communication method characterized by calculating as a target value. The communication method according to claim 13,
The communication method, wherein the transmitting terminal calculates a data retransmission amount per unit time in the target period as the determination target value. The communication method according to claim 12,
The communication method, wherein the transmitting terminal calculates a statistical amount related to a data retransmission amount in a reference period including a period past the target period as the threshold value from the history information. The communication method according to claim 16, wherein
The communication method, wherein the transmitting terminal calculates a maximum data retransmission amount generated in an arbitrary unit time in the reference period as the threshold value. The communication method according to claim 16, wherein
The transmission terminal occurred per arbitrary round operation consisting of a set of data transmission performed between the transmission terminal and the reception terminal and a reception confirmation notification corresponding thereto in the reference period. A communication method characterized by calculating a maximum data retransmission amount as the threshold value. The communication method according to claim 12,
When data communication is performed using a plurality of channels connected to the receiving terminal in parallel, the number of retransmission channels in which data retransmission has occurred among these channels in an arbitrary target period is calculated from the history information. A communication method that calculates as a determination target value and performs the delivery confirmation when the determination target value exceeds a predetermined threshold value. The communication method according to claim 19,
The communication method, wherein the transmitting terminal calculates the number of retransmission channels in a reference period including a period past the target period as the threshold value from the history information. The communication method according to claim 12,
When the transmitting terminal performs data communication using a plurality of channels connected to the receiving terminal in parallel, a statistic regarding the amount of data retransmission on these channels in an arbitrary target period A communication method characterized in that it is calculated from the information as the determination target value, and the delivery confirmation is transmitted when the determination target value exceeds a predetermined threshold value. The communication method according to claim 21, wherein
The communication method, wherein the transmitting terminal calculates, as the threshold value, from the history information, a statistic regarding the data retransmission amount in these channels in a reference period including a period past the target period. A communication system that performs data delivery confirmation from a transmission terminal to a reception terminal before retransmitting data from the transmission terminal to the reception terminal during data communication between the transmission terminal and the reception terminal,
A data communication system comprising the data communication terminal according to any one of claims 1 to 11 as the transmission terminal. When retransmitting data in response to a communication error that occurred during data communication with the receiving terminal, the computer of the communication terminal that confirms data delivery to the receiving terminal before the data retransmission,
The program for performing the process of the transmission terminal in the communication method as described in any one of Claims 12-22.

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