JP2000083023A - Method and system for distributing data and recording medium recording its program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten a retransmission time and to reduce traffic by allowing a transmitting terminal to simultaneously distribute one receiving terminal for every plural receiving terminals as a selected receiving terminal and making a selected receiving terminal, another selected receiving terminal or the transmitting terminal as a retransmission request destination when the receiving terminal or the selected receiving terminal receives error data. SOLUTION: A transmitting terminal selects each one as a selected receiving terminal for every plural receiving terminals and simultaneously distributes video data to be generated to these and each receiving terminal through hubs HUB and routers in a real time. When receiving terminals A2, A3, B2, B3, C2 and C3 receive error data of simultaneous distribution, the selected receiving terminals A1, B1 and C1 are respectively made as each of a retransmission request destination. Also, when the selected receiving terminals A1, B1 and C1 receive error data, the other selected receiving terminals or the transmitting terminal are made as a retransmission request destination. Thus, it is possible to simultaneously and parallelly perform retransmission between the transmitting terminal and a selected receiving terminal and between a selected receiving terminal and a receiving terminal and a retransmission time is shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to remote education over an IP network, distribution of real-time media for remote monitoring, etc., due to router congestion on an IP network, buffer overflow at a receiving terminal, and the like. In order to eliminate the disturbance and stoppage of the received video due to data error and loss, these error data and loss data are recovered in real time and highly reliable, and the video data generated in real time can be transmitted to multiple receiving terminals in real time. The present invention also relates to a data distribution method and system and a program for enabling simultaneous and reliable distribution.

[0002]

2. Description of the Related Art There is an increasing demand for remote education and remote monitoring through the distribution of real-time media over an IP network. However, when real-time media distribution is performed, there is a problem in that congestion of a router on an IP network, data error due to buffer overflow at a receiving terminal, disturbance of received video due to loss, and stoppage. Conventionally, there is a retransmission method as a method for recovering such error data and loss data.

[0003]

When real-time media distribution is performed, there is a demand for a method of recovering the above error data and loss data in real time and with high reliability.

[0004] However, in the above conventional retransmission system,
When the receiving terminal requests retransmission from the transmitting terminal, a new packet loss occurs because the retransmission time required for retransmission is long, the traffic of the retransmission request is concentrated, and the load on the transmitting terminal and the network device increases. Is mentioned as a problem.

Therefore, how to shorten the retransmission time and how to reduce the concentration of traffic for retransmission requests are issues.

Accordingly, an object of the present invention is to provide a data distribution method and system capable of recovering error data and loss data in real time and with high reliability while shortening retransmission time and reducing traffic, and a program therefor. And

[0007]

The present invention solves the above-mentioned problems in the data distribution method and system by the following means for dispersing and localizing retransmission requests.

[0008] One of the means is a data distribution method for a transmitting terminal to simultaneously distribute video data generated in real time to a plurality of receiving terminals, wherein the transmitting terminal selects one receiving terminal for each of the plurality of receiving terminals. And having the receiving terminal as a selective receiving terminal, wherein the receiving terminal receives error data when the transmitting terminal broadcasts simultaneously to the plurality of receiving terminals including the selective receiving terminal, Comprising the step of making the selected receiving terminal a retransmission request destination, wherein the selected receiving terminal receives error data when the transmitting terminal broadcasts simultaneously to a plurality of receiving terminals including the selected receiving terminal. And a step of setting another selected receiving terminal or the transmitting terminal as a retransmission request destination.

Alternatively, when the transmitting terminal determines the selected receiving terminal, the receiving terminal measures a round trip time of a data packet with another receiving terminal and the transmitting terminal, and The measured value of the round trip time with the transmitting terminal is compared with a predetermined threshold value. If the measured value is shorter than the threshold value, the transmitting terminal is set as a retransmission request destination, and the measured value is determined by the threshold value. If longer, sending its own address and measurement to the transmitting terminal, and receiving the address and measurement sent from the receiving terminal to obtain the address and measurement of each receiving terminal Wherein the transmitting terminal classifies the acquired addresses of the receiving terminals as a group for each address of a plurality of receiving terminals connected to the same segment, and for each of the classified groups Comparing all measured values in the group, selecting a receiving terminal having the shortest measured value, and deciding the selected receiving terminal as a selected receiving terminal of each group. Is the way.

Alternatively, in the step of determining the retransmission request destination by the receiving terminal, the transmitting terminal transmits the determined addresses and measurement values of all the selected receiving terminals to all the receiving terminals; Receiving the transmitted address of the selected receiving terminal and the measurement value, and the receiving terminal compares the received addresses of all the selected receiving terminals with its own address, and the selected receiving terminal matches its own address. If no such address exists, the selected receiving terminals belonging to the same group are set as retransmission request destinations.

Alternatively, in the step of determining the retransmission request destination by the selected receiving terminal, the transmitting terminal transmits the determined addresses and measured values of all the selected receiving terminals to all receiving terminals including the selected receiving terminal. And the receiving terminal,
Receiving the transmitted address of the selected receiving terminal and the measurement value, and the receiving terminal compares the received addresses of all the selected receiving terminals with its own address, and the selected receiving terminal matches its own address. If there is an address of the selected receiving terminal itself, comparing the measured values of all the selected receiving terminals including itself, and selecting the selected receiving terminal which is a measured value shorter than its own measured value, The receiving terminal as the selected receiving terminal measures the round trip time with the selected selected receiving terminal, and compares the measured value with the measured value of its own transmitting terminal, and selects the shortest measured value. Setting the receiving terminal or the transmitting terminal as a retransmission request destination.

Alternatively, in a data distribution system in which a transmitting terminal simultaneously distributes video data generated in real time to a plurality of receiving terminals, the transmitting terminal includes a simultaneous distribution means for simultaneously distributing video data to the plurality of receiving terminals. Retransmission means for retransmitting the video data when there is a retransmission request from the receiving terminal, selecting one receiving terminal for each group of the plurality of receiving terminals, and selecting the receiving terminal as a selected receiving terminal Selected receiving terminal determining means for transmitting to the receiving terminals, the receiving means, the receiving terminal receiving video data broadcast from the transmitting terminal to the plurality of receiving terminals and the selected receiving terminal. If error data is received in the received video data, it is determined whether or not itself is the selected receiving terminal. A retransmission request destination for the selected receiving terminal of the group and a retransmission request destination for another selected receiving terminal or transmitting terminal when the selected receiving terminal is the selected receiving terminal. It is a distribution system.

Alternatively, the receiving terminal includes a round-trip time measuring means for measuring a round-trip time of a data packet with the transmitting terminal, and a measured value of the round-trip time with the transmitting terminal measured by the round-trip time measuring means. Compare the threshold value, if the measured value is shorter than the threshold value, the transmitting terminal as a retransmission request destination, if the measured value is longer than the threshold value, the own terminal and the measured value to the transmitting terminal Transfer means for sending, wherein the selecting means for selecting the receiving terminal of the sending terminal receives the address and measured value of the receiving terminal sent by the transferring means and obtains the address and measured value of each receiving terminal. And classifying the address of each receiving terminal obtained by the obtaining means as a group for each address of a plurality of receiving terminals connected to the same segment, and for each group classified by the classification means It compares all measurements in the group,
And a classifying means for selecting a receiving terminal having the shortest measured value and determining the selected receiving terminal as a selected receiving terminal of each group.

Alternatively, the transmitting terminal includes transmitting means for transmitting the determined addresses and measured values of all the selected receiving terminals to all the receiving terminals, wherein the receiving terminal transmits the selected reception data transmitted by the transmitting means. A receiving unit that receives the address of the terminal and the measured value, the retransmitting unit compares the addresses of all the selected receiving terminals received by the receiving unit with its own address, and selects the selected receiving terminal that matches its own address. If there is no address, the data distribution system is characterized in that the selected receiving terminals of the same group by the classifying unit are to be retransmission request destinations.

Alternatively, the transmitting terminal includes transmitting means for transmitting the measured values of all the selected receiving terminals together with the measured values to all the receiving terminals, and the receiving terminal transmits the measured values by the transmitting means. Receiving means for receiving an address and a measurement value of the selected receiving terminal, wherein the round-trip time measuring means measures a round-trip time of a data packet with a transmitting terminal and another receiving terminal; and The address of all selected receiving terminals received by the means is compared with its own address, and if there is an address of the selected receiving terminal that matches its own address, it is regarded as the selected receiving terminal, and the addresses of all selected receiving terminals including itself are Compare the measured values, select a selected receiving terminal that is a measured value shorter than its own measured value, and determine the round-trip time with the selected selected receiving terminal by the round-trip time measuring method. , And compares the measured value with the measured value of its own transmitting terminal, and selects the selected receiving terminal or transmitting terminal which is the shortest measured value as a retransmission request destination. It is.

Further, the present invention provides a recording medium having a data distribution program recorded thereon, wherein the program for causing a computer to execute the steps of the data distribution method of the present invention is recorded on a computer-readable recording medium. is there.

In the present invention, the receiving terminal measures the round trip time with the transmitting terminal, and if the measured value is shorter than the threshold value in advance, sets the transmitting terminal as the retransmission request destination. If it is longer than the threshold, the receiving terminal sends its address and measurement to the transmitting terminal.

The transmitting terminals are classified as a group for each of a plurality of receiving terminals connected to the same segment. The transmitting terminal compares all the measured values for each group, and selects the receiving terminal having the shortest measured value as a selected receiving terminal in the group.

The transmitting terminal transmits the addresses and measured values of all the selected receiving terminals to all the receiving terminals.

The receiving terminal receives them, compares the addresses of all the selected receiving terminals with its own address, and if there is no matching address, selects the selected receiving terminals of the same group as the retransmission request destination.

If there is a matching address, the receiving terminal sets itself as the selected receiving terminal and selects the selected receiving terminal having a measured value shorter than its own measured value. The selected receiving terminal measures the round trip time with the selected selected receiving terminal. The selected receiving terminal compares these measured values with the measured values of its own transmitting terminal, and sets the selected receiving terminal or the transmitting terminal having the shortest measured value as the retransmission request destination.

As described above, the transmitting terminal selects the receiving terminal having the shortest round trip time with the transmitting terminal among the receiving terminals included in the group as the selected receiving terminal. The reason is that those receiving terminals have few network devices between them and the transmitting terminal, and are most likely to be affected by data errors and losses by the network devices.

As described above, the receiving terminal sets the selected receiving terminals included in the same group as the retransmission request destination. The reason is that, among the selected receiving terminals, the time required for retransmission is the shortest, and the traffic given to the entire network can be reduced by localizing the traffic of the retransmission request within the group.

As described above, the selective receiving terminal sets only the transmitting terminal or the selective receiving terminal having the shortest round trip time as the retransmission request destination. This is because the time required for retransmission is the shortest, and by localizing the traffic of the retransmission request among the limited groups, the traffic given to the entire network can be reduced.

As described above, the transmitting terminal is a selective receiving terminal,
The selected receiving terminal performs retransmission hierarchically with another selected receiving terminal or a transmitting terminal. The reason is that retransmission is performed simultaneously and in parallel, so that the retransmission time can be reduced.

[0026]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIGS. 1 and 2 are block diagrams showing one embodiment of the configuration of the data distribution system according to the present invention.
1 and 2, each terminal is connected to the same network. The data distribution system includes transmitting terminals 1 and 1
And a plurality of receiving terminals 2. Sending terminal 1
Are the simultaneous distribution means 11, retransmission means 12, transmission means 1
3, an acquisition unit 14, and a classification unit 15. On the other hand, the receiving terminal 2 includes a retransmitting unit 21, a round trip time measuring unit 22, a transferring unit 23, and a receiving unit 24. Among the receiving terminals, those selected as the selected receiving terminals by the processing of the transmitting terminal 1 are referred to as selected receiving terminals 3 to distinguish them from general receiving terminals. Like the receiving terminal 2, the selective receiving terminal 3 includes a retransmitting unit 31, a round trip time measuring unit 32, a transferring unit 33, and a receiving unit.

FIGS. 3, 4 and 5 are processing flow charts showing an example of operation of each part of each terminal in the data distribution system and an embodiment of the data distribution method of the present invention. FIG. 4 is a processing flowchart of the receiving terminal, and FIG. 5 is a processing flowchart of the transmitting terminal. Here, it is assumed that the data distribution system includes only a plurality of receiving terminals 2 including a transmitting terminal 1 and a selective receiving terminal 3.

The retransmission request destination of each receiving terminal 2 is determined by the processing in the receiving terminal 2. This process is performed in parallel when the receiving terminal 2 is receiving video data by the receiving means 24. Initially, the receiving terminal 2
2, the round trip time with the transmitting terminal 1 is measured (step 101). When the measured value is shorter than the predetermined threshold, the retransmitting means 21 of the receiving terminal 2 sets the transmitting terminal 1 as a retransmission request destination (steps 102 and 104). If the measured value is longer than the predetermined threshold, the receiving terminal 2
3, the measured value and its own address are sent to the transmitting terminal 1 (steps 102 and 103). Thereafter, the process waits until the addresses of the selected receiving terminals and their measured values are received from the transmitting terminal 1 (step 105).

The transmitting terminal 1 waits until receiving addresses and measured values from the plurality of receiving terminals 2 (step 10).
9). When the transmitting terminal 1 receives them from the plurality of receiving terminals 2 by the acquisition unit 14, the classifying unit 15 classifies the addresses of the plurality of receiving terminals 2 connected to the same segment as a group (steps 109 and 11).
0). After that, the classifying unit 15 compares all the measured values for each group, and determines the shortest measured value for the receiving terminal 2.
Is set as the selective receiving terminal (step 111). Next, the transmitting terminal 1 transmits the address and the measured value of each selected receiving terminal to all the receiving terminals 2 by the transmitting means 13 (step 11).
2).

When the receiving terminal 2 receives the addresses of the selected receiving terminals and the measured values thereof from the transmitting terminal 1 by the receiving means 24, the retransmitting means 21 compares the own address with the addresses of the selected receiving terminals. If they do not all match, the retransmitting means 21 selects the selected receiving terminal 3 of the same group.
Is the retransmission request destination (steps 105, 106 and 10).
8). If they match, a selection receiving terminal determination process is executed (steps 105, 106 and 107). In the selection receiving terminal determination process, the retransmission unit 21 sets itself as the selection receiving terminal 3 (step 1071). Selective receiving terminal 3
The retransmitting means 31 of the receiving terminal that has become the selected terminal compares the measured values of all the selected receiving terminals including its own measured value, and selects the selected receiving terminal that is a measured value shorter than its own measured value (step 1).
072). The retransmitting means 31 measures the round trip time between the selected selected receiving terminals by the round trip time measuring means 32 (step 1073), compares all the measured values with the measured values between its own transmitting terminals, The selected receiving terminal or transmitting terminal 1 having the shortest measured value is set as the retransmission request destination (step 1074).

FIG. 6 shows an example of a network targeted by the present invention. In this network, a transmitting terminal and a receiving terminal are mutually connected via a router and a hub (HUB).

First, a method of determining a selected receiving terminal in this network will be described below.

First, each of the receiving terminals A1 to C3 measures the round trip time with the transmitting terminal. Table 1 shows the measured values of each receiving terminal.
Shown in Each receiving terminal compares the measured value with a predetermined threshold. If the threshold is 7 ms, each measurement is longer than the threshold. In this case, each receiving terminal sends its own measured value and address to the transmitting terminal. Table 2 shows the addresses of the receiving terminals.

[0035]

[Table 1]

[0036]

[Table 2]

The transmitting terminal classifies the addresses received from each receiving terminal as a group for each address of a plurality of receiving terminals connected to the same segment. Table 3 shows the addresses and measured values of the receiving terminals included in each group.

[0038]

[Table 3]

The transmitting terminal compares all the measured values for each group, and determines the receiving terminal having the shortest measured value as the selected receiving terminal. The transmitting terminal sets A1, B1, and C1 as the selected receiving terminals in each group of Table 3.

Next, a method of determining the retransmission request destination of the receiving terminal will be described.

The transmitting terminal transmits the addresses and measured values of all the selected receiving terminals to all the receiving terminals. The receiving terminal compares the address of the selected receiving terminal received from the transmitting terminal with its own address, and if there is no matching address, selects the selected receiving terminal in the same group as the retransmission request destination. Therefore, in FIG. 6, A2 and A3 represent A1, B2 and B3 represent B1, C2,
C3 sets C1 as a retransmission request destination.

Next, a method of determining the retransmission request destination of the selected receiving terminal will be described.

When determining the retransmission request destination of the selected receiving terminal C1, C1 compares the measured value of the other selected receiving terminal with its own measured value, and selects the selected receiving terminal A1, which is a measured value shorter than its own measured value. Select B1. Table 4 shows the measured values of the all-selected receiving terminals. C1 measures the round trip time between the selected selected receiving terminals A1 and B1, and compares those measured values with those measured with its own transmitting terminal. Table 5 shows the measured values with the other selected receiving terminals and the measured values with the own transmitting terminal. When compared, C1 sets the selected receiving terminal B1, which is the shortest measured value, as the retransmission request destination.

[0044]

[Table 4]

[0045]

[Table 5]

Similarly, when determining the retransmission request destination of the selected receiving terminal B1, B1 compares its own measured value with the measured value of another selected receiving terminal. From Table 4, the measured value of B1 is the shortest. In this case, B1 sets the transmitting terminal as the retransmission request destination.

When determining the retransmission request destination of the selected receiving terminal A1, A1 compares its own measured value with the measured value of another selected receiving terminal. From Table 4, A1 selects the selected receiving terminal B1 whose measured value is shorter than its own measured value. A1 measures the round trip time with the selected B1, and compares the measured value with the measured value with its own transmitting terminal. Table 6 shows the measured values with the other selected receiving terminals and the measured values with the own transmitting terminal. When compared, A1 sets the transmitting terminal having the shortest measured value as the retransmission request destination.

[0048]

[Table 6]

FIGS. 7 to 12 show the data flow in the data distribution system shown in FIGS. The numbers in parentheses in the figure indicate the order of data flow.

FIG. 7 shows a data flow when video data is simultaneously distributed to a plurality of receiving terminals. The video data is simultaneously distributed from the broadcasting means 11 of the transmitting terminal 1 to the plurality of receiving terminals 2 through the network.
Receives the broadcasted video data by, for example, the receiving means 24 (1).

FIG. 8 shows the flow of data when measuring the round trip time with the transmitting terminal to determine the retransmission request destination when an error or loss is detected in the data received by the receiving terminal 2 and a retransmission request is determined. Is shown. The round-trip time measuring means 22 of the receiving terminal 2 transmits a data packet for round-trip time measurement to the transmitting terminal 1 (1). In response to this, the transmitting terminal 1 returns a data packet for response to the receiving terminal 2 by, for example, the retransmitting means 12 (2). The receiving terminal 2 receives the returned data packet by the round-trip time measuring means 22 and measures the round-trip time from the transmission of the data packet to the return.

FIG. 9 shows a flow of data until a retransmission request destination is determined when the round trip time between the receiving terminal 2 and the transmitting terminal 1 measured in FIG. 8 is longer than the threshold value. I have. The measured value of the round trip time with the transmitting terminal 1 measured by the round trip time measuring unit 22 is transmitted to the transfer unit 23 together with the address of the receiving terminal 2 (1), and transmitted to the transmitting terminal 1 through the network by the transfer unit 23 (2). ). The transmitting terminal 1 categorizes the transmitted addresses from the plurality of receiving terminals and the measured round trip time by the acquiring unit 14 into the classifying unit 15.
(3). The classification means 15 classifies the receiving terminals into groups based on the addresses, determines the receiving terminal having the minimum round-trip time measurement value as the selected receiving terminal for each group, and selects the selected receiving terminals for each group and their selected receiving terminals. The measured round-trip time is sent to the transmitting means 13 (4). The transmitting means 13 transmits the address of each selected receiving terminal and the measured round-trip time thereof to all the receiving terminals 2 through the network (5). Each receiving terminal 2 receives them by the receiving means 24.

FIG. 10 shows data when transmission terminal 1 is determined to be a retransmission request destination because the round trip time measurement between reception terminal 2 and transmission terminal 1 measured in FIG. 8 is shorter than the threshold value. It shows the flow. The receiving terminal 2 includes a retransmission unit 2
1 transmits a retransmission request to the transmitting terminal 1 (1). In response to this, the transmitting terminal 1 retransmits the video data through the network by the retransmitting means 12 and transmits it to the receiving terminal 2.
Is re-received. The data flow when the selected receiving terminal 3 determines the transmitting terminal 1 as the retransmission request destination also follows this.

FIG. 11 shows a case where the receiving terminal 2 determines the retransmission request destination when the transmitting terminal 1 selects the receiving terminal, so that the measured round-trip time with the transmitting terminal is shorter than its own measured value. Select the receiving terminal, and select the selected receiving terminal 3
9 shows a data flow when a round trip time between the two is measured. The round-trip time measuring means 22 of the receiving terminal 2 transmits a data packet for round-trip time measurement to the selected receiving terminal 3 (1). Upon receiving this, the selective receiving terminal 3 returns a data packet for response to the receiving terminal 2 by, for example, the retransmitting means 31 (2). In the receiving terminal 2,
The reciprocating time measuring means 22 receives the returned data packet and measures the reciprocating time from the transmission of the data packet to the return.

FIG. 12 shows that the receiving terminal 2 is
Shows the flow of data when is determined to be a retransmission request destination. The receiving terminal 2 transmits a retransmission request to the selected receiving terminal 3 by the retransmitting means 21 (1). In response to this, the selective receiving terminal 3 retransmits the video data stored therein by the retransmitting means 31 through the network, and the receiving terminal 2 rereceives the video data and the retransmitting means 21 receives it. The data flow when the selected receiving terminal 3 determines another selected receiving terminal as a retransmission request destination also conforms to this.

In the present invention, the steps of the processing described in FIGS. 3, 4 and 5 can be executed by a computer, or the means described in FIGS. 1 and 2 can be operated by a computer. Needless to say, a program for causing a computer to execute the processing steps or a program for causing a computer to function as the means can be stored in a computer-readable recording medium such as an FD (floppy disk) or the like. , MO, ROM, memory card, CD,
Provided by recording on DVD, removable disk, etc.
It is possible to distribute. A transmitting terminal as in the present invention,
In a system consisting of a receiving terminal and a selective receiving terminal,
The program of each terminal may be recorded together on one recording medium, and the program required by each terminal may be activated, or the program required by each terminal may be separately recorded on a separate recording medium. You may make it.

[0057]

According to the present invention described above, the effect of shortening the retransmission time can be obtained by performing retransmission simultaneously and in parallel between the transmitting terminal and the selected receiving terminal and between the selected receiving terminal and the receiving terminal. .

Further, each receiving terminal requests retransmission only to the selected receiving terminal in the same segment, and the selected receiving terminal requests retransmission only to the selected receiving terminal or transmitting terminal in the adjacent segment, and distributes the retransmission request in a distributed and local manner. This has the effect of reducing traffic.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a transmitting terminal and a configuration of a receiving terminal in an embodiment of a data distribution system of the present invention.

FIG. 2 is a block diagram showing a configuration of a selective receiving terminal and a configuration of a receiving terminal in an embodiment of the data distribution system of the present invention.

FIG. 3 is a processing flow chart showing an example of an operation of the data distribution system of the embodiment and a process of a receiving terminal in an embodiment of the data distribution method of the present invention.

FIG. 4 is a processing flowchart showing a selected receiving terminal determination process in the above-described receiving terminal process.

FIG. 5 is a processing flow chart showing an operation example of the data distribution system of the embodiment and a process of the transmission terminal in the data distribution method according to the embodiment of the present invention;

FIG. 6 is a diagram illustrating an example of a target network in the embodiment.

FIG. 7 is a diagram for explaining a data flow (No. 1) in the data distribution system of the embodiment.

FIG. 8 is a diagram for explaining a data flow (No. 2) in the data distribution system of the embodiment.

FIG. 9 is a diagram illustrating a data flow (part 3) in the data distribution system of the embodiment.

FIG. 10 is a diagram illustrating a data flow (No. 4) in the data distribution system of the embodiment.

FIG. 11 is a diagram illustrating a data flow (No. 5) in the data distribution system of the embodiment.

FIG. 12 is a diagram illustrating a data flow (No. 6) in the data distribution system of the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Transmission terminal 11 ... Simultaneous distribution means 12 ... Retransmission means 13 ... Transmission means 14 ... Acquisition means 15 ... Classification means 2 ... Receiving terminal 21 ... Retransmission means 22 ... Round trip time measuring means 23 ... Transfer means 24 ... Receiving means 3 .... Selection Receiving terminal 31 Retransmission means 32 Round trip time measuring means 33 Transfer means 34 Receiving means

Claims (9)

[Claims] 1. A data distribution method for a transmitting terminal to simultaneously distribute video data generated in real time to a plurality of receiving terminals, wherein the transmitting terminal selects one receiving terminal for each of the plurality of receiving terminals. Setting the receiving terminal as a selective receiving terminal, wherein the receiving terminal receives the error data when the transmitting terminal broadcasts to the plurality of receiving terminals including the selective receiving terminal at the same time. Having a receiving terminal as a retransmission request destination, wherein the selected receiving terminal receives error data when the transmitting terminal broadcasts simultaneously to a plurality of receiving terminals including the selected receiving terminal; A data distribution method, comprising the step of setting a selected receiving terminal or the transmitting terminal as a retransmission request destination. 2. The method according to claim 1, wherein the transmitting terminal determines a selected receiving terminal, wherein the receiving terminal measures round-trip time of a data packet with another receiving terminal and the transmitting terminal. Compare the measured value of the round trip time with the transmitting terminal and a predetermined threshold value, and if the measured value is shorter than the threshold value, the transmitting terminal as a retransmission request destination,
When the measured value is longer than the threshold value, sending its own address and measured value to the transmitting terminal; and the transmitting terminal receives the address and the measured value sent from the receiving terminal, and receives the measured value. Obtaining an address and a measurement value; the transmitting terminal classifying the obtained address of each receiving terminal as a group for each address of a plurality of receiving terminals connected to the same segment; and the classified group. For each, compare all the measured values in the group, select the receiving terminal that is the shortest measured value,
Deciding the selected receiving terminal as a selected receiving terminal of each group. The data distribution method according to claim 1, further comprising: 3. The receiving terminal, when determining a retransmission request destination, a transmitting terminal transmitting the determined addresses and measured values of all the selected receiving terminals to all receiving terminals, Receiving the transmitted address of the selected receiving terminal and the measurement value; and the receiving terminal compares the received addresses of all the selected receiving terminals with its own address, and the selected receiving terminal matches its own address. 3. The data distribution method according to claim 2, further comprising the step of: setting the selected receiving terminals belonging to the same group to the retransmission request destination when the address does not exist. 4. The transmitting terminal, when the selected receiving terminal determines a retransmission request destination, transmitting an address and a measurement value of all the determined selected receiving terminals to all receiving terminals including the selected receiving terminal. The receiving terminal receives the transmitted address of the selected receiving terminal and the measurement value, and the receiving terminal compares the received addresses of all the selected receiving terminals with its own address, If there is an address of the selected receiving terminal that matches the address, set itself as the selected receiving terminal, compare the measured values of all the selected receiving terminals including itself, and select the selected receiving terminal that is shorter than its own measured value Performing a step of measuring a round trip time between the selected receiving terminal and the receiving terminal that has set itself as the selected receiving terminal; and measuring the measured value and its own transmitting terminal. Comparing the values, the shortest and steps of the retransmission request destination measure is selected receiving terminal or the transmission terminal, the data distribution method according to claim 2, characterized in that it has. 5. A data distribution system for a transmitting terminal to simultaneously distribute video data generated in real time to a plurality of receiving terminals, the transmitting terminal comprising: a simultaneous distribution means for simultaneously distributing video data to a plurality of receiving terminals. Retransmission means for retransmitting the video data when there is a retransmission request from the receiving terminal, selecting one receiving terminal for each group of the plurality of receiving terminals, and selecting the receiving terminal as a selected receiving terminal Selected receiving terminal determining means for transmitting the information to all receiving terminals, the receiving terminal comprising: receiving means for receiving video data broadcast from the transmitting terminal to a plurality of receiving terminals and the selected receiving terminal simultaneously. And, if error data is received in the received video data, determine whether or not itself is the selective receiving terminal,
When the selected receiving terminal is not the selected receiving terminal, the selected receiving terminal of the same group is set as the retransmission request destination, and when the selected receiving terminal is the selected receiving terminal, another selected receiving terminal or the transmitting terminal is set as the retransmission request destination. , A data distribution system. 6. The receiving terminal includes: a round-trip time measuring means for measuring a round-trip time of a data packet with the transmitting terminal; and a predetermined value of a round-trip time with the transmitting terminal measured by the round-trip time measuring means. Compare the threshold value, if the measured value is shorter than the threshold value, the transmitting terminal as a retransmission request destination, if the measured value is longer than the threshold value, the own terminal and the measured value to the transmitting terminal Transfer means for transmitting, the selecting means for selecting the receiving terminal of the transmitting terminal, obtaining means for receiving the address and measured value of the receiving terminal sent by the transferring means and obtaining the address and measured value of each receiving terminal And classifying the address of each receiving terminal obtained by the obtaining means as a group for each address of a plurality of receiving terminals connected to the same segment, and for each group classified by the classifying means, Grouping means for comparing all measured values in the group, selecting a receiving terminal having the shortest measured value, and determining the selected receiving terminal as a selected receiving terminal of each group. Item 6. The data distribution system according to Item 5. 7. The transmitting terminal includes transmitting means for transmitting the determined addresses and measured values of all the selected receiving terminals to all the receiving terminals, wherein the receiving terminal transmits the selected reception data transmitted by the transmitting means. A receiving unit that receives the address of the terminal and the measured value, the retransmitting unit compares the addresses of all the selected receiving terminals received by the receiving unit with its own address, and selects the selected receiving terminal that matches its own address. 7. The method according to claim 6, wherein when there is no address, the selected receiving terminals of the same group by the classifying unit are set as retransmission request destinations.
Data distribution system as described. 8. The transmitting terminal comprises transmitting means for transmitting the measured values of all the selected receiving terminals together with the measured values to all the receiving terminals, wherein the receiving terminal transmits the measured values to the selected receiving terminals. Receiving means for receiving an address and a measurement value of the selected receiving terminal, wherein the round-trip time measuring means measures a round-trip time of a data packet with a transmitting terminal and another receiving terminal; and The address of all selected receiving terminals received by the means is compared with its own address, and if there is an address of the selected receiving terminal that matches its own address, it is regarded as the selected receiving terminal, and the addresses of all selected receiving terminals including itself are Compare the measured values, select a selected receiving terminal that is a measured value shorter than its own measured value, and determine the round trip time with the selected selected receiving terminal by the round trip time measuring means. 7. The apparatus according to claim 6, wherein the measured value is compared with the measured value of the transmitting terminal, and the selected receiving terminal or the transmitting terminal having the shortest measured value is set as the retransmission request destination. Data distribution system. 9. Any one of claims 1 to 4
A recording medium recording a data distribution program, wherein a program for causing a computer to execute the steps in the data distribution method described in the paragraph is recorded on a recording medium readable by the computer.