JP2003348186A - Method and device for transmitting electronic data - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a device for transmitting electronic data, which improve the reliability of data transfer to realize data transfer of high quality when delivering electronic data to an unspecified reception terminal in real time. <P>SOLUTION: The method includes a step where the presence or the absence of a dropped-out sequence number is discriminated in accordance with the sequence numbers of respective packets received in a reception terminal and a retransmission request signal of a corresponding packet is transmitted together with retransmission request frequency information from the reception terminal to a transmission terminal and a step where it is discriminated whether retransmission should be performed or not on the basis of retransmission request frequency information included in the retransmission request signal received in the transmission terminal and transmission frequency information of the corresponding packet in a transmission history and the corresponding packet is transmitted again. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic data transmission method for transmitting electronic data from a transmission terminal to an unspecified reception terminal, and more particularly, to a UDP / IP (User Datagram Protocol / UDP).
The present invention relates to an electronic data transmission method and apparatus for transmitting a packet from a transmission terminal to a reception terminal using an Internet Protocol (Transmission Protocol).

[0002]

2. Description of the Related Art As a transmission protocol in packet communication, TCP / IP (Transmission Control Protocol / Inter
net Protocol) and UDP / IP (User Datagram Protocol)
/ Internet Protocol).

[0003] In TCP / IP, since retransmission processing is sequentially performed when a lost packet occurs, data transfer is highly reliable but lacks immediacy. Data transfer to the receiving terminal, so-called multicasting, is not possible.

On the other hand, since UDP / IP is non-procedure,
It is a transfer method that has immediacy and allows multicasting, and is suitable for multimedia stream data distribution. However, UDP / IP has a disadvantage that data transfer is less reliable than TCP / IP.

[0005]

[Table 1]

[0006]

In the case where data distribution to a plurality of receiving terminals is performed using such UDP / IP,
If it is possible to configure the transmitting terminal to retransmit a packet that could not be received by each receiving terminal, it is considered that the reliability of data transfer can be maintained high.

[0007] The present invention is not limited to the method of distributing electronic data using packet communication or the method of distributing electronic data using the UDP / IP transmission protocol. In a case where electronic data is divided and sequentially distributed to an unspecified receiving terminal, It is desirable to ensure the immediacy and reliability of data transfer.

According to the present invention, there is provided an electronic data transmission method capable of improving reliability of data transfer and realizing high quality data transfer when delivering electronic data to an unspecified receiving terminal in real time. We propose the device.

[0009]

According to a first aspect of the present invention, there is provided an electronic data transmitting method for transmitting electronic data from a transmitting terminal to an unspecified receiving terminal. A step of dividing the data into a plurality of pieces of data, adding a sequence number indicating the continuity thereof, and transmitting the data from the transmitting terminal to the receiving terminal, and a step of recording a transmission history including information on the number of times of transmission of each of the divided data transmitted from the transmitting terminal And storing each divided data received in the receiving terminal in the storage means based on the sequence number, and determining whether there is a missing sequence number from the sequence number of each divided data received in the receiving terminal. If there is a sequence number, the retransmission request count information of the corresponding divided data is incremented and recorded. Transmitting the retransmission request signal of the corresponding divided data from the receiving terminal to the transmitting terminal, and transmitting the retransmission request number information included in the retransmission request signal received by the transmitting terminal and the transmission number information of the corresponding divided data in the transmission history. It is determined whether or not retransmission is to be performed on the basis of the retransmission, and when retransmission is performed, the transmission history is updated by incrementing the transmission count information of the corresponding divided data, and retransmitting the corresponding divided data is included.

In this case, it becomes possible to transmit electronic data to a plurality of receiving terminals, and to receive a retransmission request signal for divided data corresponding to a sequence number that could not be received by the receiving terminal, and Since the configuration is such that the divided data is retransmitted, the reliability of data transfer can be improved. On the transmitting terminal side, information on the number of times of transmission of each divided data is stored in the transmission history, and the number of times of retransmission request information transmitted from the receiving terminal is compared with the number of times of retransmission of the corresponding divided data. Since the retransmission processing of the divided data is performed, it is possible to prevent the retransmission from being performed repeatedly even if there is a retransmission request for the same divided data from a plurality of receiving terminals. On the receiving terminal side,
The number of retransmission requests issued for the divided data corresponding to the missing sequence number is recorded as retransmission request number information, and even if there is unreceivable divided data, multiple retries must be performed. , The missing divided data can be compensated, and the quality of the received data can be maintained at a high level. Further, since the receiving terminal side temporarily stores each divided data in the storage unit based on the sequence number, there is a slight delay from the data transmission from the transmitting terminal. By starting, the real-time property is not significantly impaired.

According to a second aspect of the present invention, there is provided the electronic data transmission method according to the first aspect, wherein the data transmission protocol is UDP / IP (User Datag).
A packet is sequentially transmitted as divided data using a ram Protocol / Internet Protocol) transmission protocol.

[0012] In this case, in packet communication using the UDP / IP transmission protocol, real-time data transmission by multicast can be performed, and the reliability of data transfer to each receiving terminal can be maintained high.

According to a third aspect of the present invention, there is provided the electronic data transmission method according to the first or second aspect, wherein the electronic data is stream data including moving image data or audio data. It is characterized by.

In this case, stream data such as moving image data and audio data can be transmitted in real time to an unspecified receiving terminal in good quality.

An electronic data transmitting apparatus according to claim 4 of the present invention is an electronic data transmitting apparatus for transmitting electronic data to an unspecified receiving terminal, wherein the electronic data is divided into a plurality of divided data. Data transmission means for transmitting from the transmitting terminal to the receiving terminal with a sequence number indicating continuity,
A transmission history storing means for storing a transmission history including information on the number of times of transmission of each divided data transmitted by the data transmitting means; and a retransmission request signal for the divided data that could not be received by the receiving terminal. Retransmission request receiving means for receiving the retransmission request information together with retransmission request number information indicating the number of times transmitted from the receiving terminal; retransmission request number information received by the retransmission request receiving means; and a transmission history stored in the transmission history storage means. Retransmission determining means for comparing whether or not to retransmit the divided data by comparing the transmission count information of the corresponding divided data, and divided data corresponding to the data transmitting means based on the determination result of the retransmission determining means And the transmission history information stored in the transmission history storage means is updated by incrementing the transmission count information of the corresponding divided data. And a chromatography data retransmission means.

In this case, it becomes possible to transmit the electronic data to a plurality of receiving terminals, and to receive a retransmission request signal of the divided data corresponding to the sequence number that could not be received by the receiving terminal, and Since the configuration is such that the divided data is retransmitted, the reliability of data transfer can be improved.

An electronic data transmitting apparatus according to a fifth aspect of the present invention is the electronic data transmitting apparatus according to the fourth aspect, wherein the data transmitting means is a UDP / IP (User Datagram Protocol).
/ Internet Protocol) It is configured to sequentially transmit packets to unspecified receiving terminals using a transmission protocol.

In this case, in packet communication using the UDP / IP transmission protocol, real-time data transmission by multicast can be made possible, and the reliability of data transfer to each receiving terminal can be maintained high.

An electronic data transmitting apparatus according to claim 6 of the present invention is the electronic data transmitting apparatus according to claim 4 or 5, wherein the electronic data is stream data including moving image data or music data. It is characterized by.

In this case, it is possible to transmit stream data including moving image data and audio data in real time while maintaining a highly reliable state.

An electronic data receiving apparatus according to claim 7 of the present invention is an electronic data receiving apparatus for receiving electronic data transmitted to an unspecified receiving terminal, wherein the electronic data receiving apparatus is divided into a plurality of divided data. Data receiving means for receiving electronic data transmitted from the transmitting terminal with a sequence number indicating the continuity, and data storage means for accumulating each divided data received by the data receiving means based on the sequence number, A missing data determining means for determining the presence or absence of a missing sequence number from the sequence number of each divided data received by the data receiving means, a sequence number determined to be missing by the missing data determining means,
Missing data list storage means for storing retransmission request number information indicating the number of times the corresponding divided data retransmission request signal has been transmitted, and retransmission request number information for the divided data corresponding to the sequence number stored in the missing data list storage means And a retransmission requesting means for transmitting to the transmitting terminal together with a retransmission request signal of the corresponding divided data.

In this case, the number of retransmission requests for the divided data corresponding to the missing sequence number is recorded as retransmission request number information on the receiving terminal side. Even in this case, the missing divided data can be compensated by performing the retry a plurality of times, and the quality of the received data can be maintained at a high level.

An electronic data receiving apparatus according to claim 8 of the present invention is the electronic data receiving apparatus according to claim 7, wherein the data receiving means is a UDP / IP (User Datagram Protocol).
/ Internet Protocol) It is configured to sequentially receive packets transmitted to an unspecified receiving terminal using a transmission protocol.

In this case, in packet communication using the UDP / IP transmission protocol, data can be received in real time by multicasting, and the reliability of received electronic data can be maintained high.

An electronic data receiving apparatus according to a ninth aspect of the present invention is the electronic data receiving apparatus according to the seventh or eighth aspect, wherein the electronic data is stream data including moving image data or music data. It is characterized by the following.

In this case, it is possible to receive stream data including moving image data and audio data in real time while maintaining a highly reliable state.

An electronic data receiving apparatus according to a tenth aspect of the present invention is the electronic data receiving apparatus according to any one of the seventh to ninth aspects, wherein the retransmission request means includes a missing data list every predetermined time. It is configured to read out the sequence number stored in the storage means and transmit a retransmission request signal.

In this case, the sequence numbers of the divided data that could not be received by the receiving device are stored in the missing data list storage means, and the retransmission request signals can be transmitted collectively at predetermined time intervals. Increase can be suppressed.

[0029] An electronic data receiving apparatus according to claim 11 of the present invention is the electronic data receiving apparatus according to any one of claims 7 to 9, wherein the retransmission requesting means is configured to transmit from the transmitting terminal or an external apparatus. It is configured to transmit a retransmission request signal based on a request confirmation signal by polling.

In this case, efficient data transfer can be realized by transmitting a retransmission request signal by polling.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [System outline configuration] 1 of the present invention
FIG. 1 shows a schematic configuration of a system to which the embodiment is adopted.

The transmitting terminal 1 is connected to a network 3 such as the Internet or a private line network, and is configured to transmit stream data to a plurality of receiving terminals 2 using a UDP / IP transmission protocol. The transmitting terminal 1 divides the stream data including audio and images into a plurality of packets, attaches a sequence number indicating the continuity of each packet, and performs multicast transmission via the network 3.

[Transmission Terminal] As shown in FIG. 2, the transmission terminal 1 includes a packet transmission unit 11, a transmission history storage unit 12,
It includes a retransmission request receiving unit 13, a retransmission determination unit 14, a packet retransmission unit 15, and the like.

The packet transmitting means 11 divides the stream data into a plurality of packets, attaches a sequence number indicating the continuity thereof, and transmits the packets from the transmitting terminal to the receiving terminal. As shown in FIG. A data input unit 111 for receiving data input; a packet generation unit 112 for generating a plurality of packets by dividing the data according to a packet size for transmitting stream data;
Includes a sequence number assigning unit 113 that assigns a sequence number based on the continuity to each of the packets generated in step S1 and a packet transmitting unit 114 that transmits each packet via the network 3.

The transmission history storing means 12 stores a transmission history including information on the number of times of transmission of each packet transmitted by the packet transmitting means 11. The transmission history storage unit 12 can be configured to store the packet transmitted by the packet transmission unit 11 as it is, and is configured to record the number of times each packet has been transmitted from the transmission terminal 1.

The retransmission request receiving means 13 receives a retransmission request signal of a packet that could not be received by the receiving terminal 2 together with retransmission request number information indicating the number of times that the retransmission request signal of the packet was transmitted from the receiving terminal 2. is there.

The retransmission determination means 14 is a retransmission request receiving means 1
3 and the transmission history storage means 1
2 is compared with the information on the number of transmissions of the corresponding packet included in the transmission history stored in No. 2 to determine whether or not to retransmit the corresponding packet. The retransmission request signal transmitted from the receiving terminal 2 includes retransmission request number information indicating the number of times the corresponding packet has been transmitted. The transmission history stored in the transmission history storage unit 12 includes transmission number information updated each time transmission is performed from the transmission terminal 1. The retransmission determination unit 14 compares the retransmission request count information transmitted from the receiving terminal 2 with the transmission count information in the transmission history, and when the retransmission request count information is equal to or greater than the transmission count information in the transmission history, It is determined that the packet is to be retransmitted.

The packet retransmitting means 15 comprises a retransmission determining means 1
4, the packet transmitting unit 11 retransmits the corresponding packet, and increments the transmission count information of the corresponding packet to transmit the packet.
2 is updated. Thus, regarding the packet retransmitted by the packet transmission unit 11, the transmission count information in the transmission history stored in the transmission history storage unit 12 can correspond to the actual transmission count.

[Receiving Terminal] As shown in FIG. 4, the receiving terminal 2 includes a packet receiving unit 21, a packet storing unit 22,
The system includes a missing packet determination unit 23, a missing packet list storage unit 24, and a retransmission request unit 25.

The packet receiving means 21 receives stream data which is divided into a plurality of packets and has a sequence number indicating the continuity thereof and which is transmitted from the transmitting terminal. Here, the packet transmitting means 1 of the transmitting terminal 1
1 is to receive each packet transmitted from the first.

The packet storage 22 stores each packet received by the packet receiver 21 based on its sequence number. For example, in the case of audio streams, RTP (Real Time Protocol)
ol) is often used, and the transmitting terminal 1 uses this RTP
The sequence number of each packet composed of unsigned 16-bit data is written in the layer and transmitted. Receiving terminal 2
On the side, each packet is sequentially stored in the packet storage unit 22 based on the sequence number written in the RTP layer. The packet storage means 22 is composed of a reception buffer for storing received packets, and an area corresponding to the sequence number is assigned to each packet.

The missing packet determining means 23 determines the presence or absence of a missing sequence number from the sequence number of each packet received by the packet receiving means 21. In the case where the sequence number of each packet is written in the RTP layer as described above, when the sequence number written in the RTP layer is analyzed and stored in the packet storage unit 22, the sequence number is invalid. By detecting the continuation, it is possible to determine that the received packet is lost.

The missing packet list storage means 24 stores the sequence number determined to be missing by the missing packet determining means 23 and retransmission request count information indicating the number of times a retransmission request signal of the corresponding packet has been transmitted. Things. When a packet loss is detected by the lost packet determination unit 23, a sequence number corresponding to the lost packet list stored in the lost packet list storage unit 24 is written. When a packet transmitted from the transmitting terminal 1 includes a packet that has been requested to be retransmitted, that is, a packet corresponding to the sequence number written in the missing packet list of the missing packet list storage unit 24 is included. In this case, this is determined by the missing packet determination means 23, and the corresponding sequence number is deleted from the missing packet list.

The retransmission request means 25 increments the retransmission request count information of the packet corresponding to the sequence number stored in the missing packet list storage means 24, and transmits the retransmission request count information and the retransmission request signal of the corresponding packet to the transmitting terminal. 1 is transmitted. The retransmission request means 25
A lost packet list stored in the lost packet list storage means 24 is referred to at predetermined time intervals, and when a sequence number is stored in the lost packet list, a retransmission request signal for a packet corresponding to this sequence number is generated.
The information is transmitted to the transmitting terminal 1 together with the incremented retransmission request count information. The timing at which the retransmission request unit 25 refers to the missing packet list is determined by setting a timer on the receiving terminal 2 side and setting a predetermined time interval (for example,
It can be configured to refer to the missing packet list at an interval of 0 msec). It is also possible to configure so as to refer to the missing packet list based on a request confirmation signal transmitted from the transmitting terminal 1 by polling.

[Operation of Transmission Terminal] The operation of the transmission terminal 1 will be described with reference to the flowchart of FIG.

In step S11, a transmission start notification signal is transmitted to each receiving terminal 2.

In step S12, the packet generator 11
A packet is generated according to the transmission packet size for the stream data to be transmitted according to 2, and the sequence number assignment unit 113 assigns a sequence number according to continuity.

In step S13, the packet transmitting unit 11
4 transmits a packet to each receiving terminal 2.

In step S 14, the transmission history related to the transmitted packet is stored in the transmission history storage unit 12. As shown in FIG. 7, the transmission history can be configured to store the packet transmitted from the packet transmission unit 114 of the transmission terminal 1 as it is, and when a missing packet that cannot be received by the reception terminal 2 occurs. Assuming that
The transmission history is stored for a predetermined time in consideration of the time required for packet retransmission processing and the like. The transmission history includes transmission count information for each packet that is incremented when a corresponding packet is retransmitted in response to a retransmission request signal from the receiving terminal 2, and the transmission count when the first transmission is performed. Set the initial value of the information to "1".

In step S15, it is determined whether or not a retransmission request signal from receiving terminal 2 has been received. If a packet retransmission request signal has been received from the receiving terminal 2, the process proceeds to step S16.

In step S16, the retransmission request count information included in the retransmission request signal is compared with the transmission count information of the corresponding packet included in the transmission history, and it is determined whether the retransmission request count information is equal to or greater than the transmission count information. Determine. Receiving terminal 2
The retransmission request signal transmitted from the terminal includes retransmission request number information regarding the number of times a retransmission request has been made from the receiving terminal 2 for the packet. The transmission history stored in the transmission history storage unit 12 includes transmission number information indicating the number of times of transmission for each packet. By configuring so as to retransmit a retransmission request signal of a packet including retransmission request number information having a value equal to or greater than the transmission number information, even if there is a retransmission request for the same packet from a plurality of receiving terminals 2, the necessary minimum By performing the retransmission processing, the congestion of the line can be eliminated, and the processing delay can be reduced. Therefore, if the retransmission request count information exceeds the transmission count information, the process proceeds to step S17 assuming that retransmission processing of the corresponding packet is performed.

In step S17, retransmission processing of the packet determined to perform retransmission processing in step S16 is executed. If the transmitted packet is stored in the transmission history storage unit 12 as it is, the packet that is determined to be subjected to the retransmission processing is read out, and the packet transmission unit 114 executes the retransmission processing.

In step S 18, the transmission count information of the retransmitted packet is incremented, and the transmission history of the transmission history storage unit 12 is updated.

In step S19, it is determined whether or not transmission of all packets has been completed. If it is determined that the transmission of all the packets of the stream data has not been completed, the process proceeds to step S12, and if it is determined that the transmission of all the packets has been completed, the process proceeds to step S20.

In step S20, an end notification signal is transmitted, and in step S21, end processing is executed.

[Operation of Receiving Terminal] The operation of the receiving terminal 2 will be described with reference to the flowchart of FIG.

In step S31, a transmission start notification signal from the transmitting terminal 1 is received.

In step S32, a packet transmitted from transmitting terminal 1 is received. Here, the packet transmitted from the transmitting terminal 1 is received by the packet receiving means 21, and the packet transmitted for the first time by the transmitting terminal 1 is retransmitted from the transmitting terminal 1 in response to a retransmission request from the receiving terminal 2. The received packet and the packet retransmitted from the transmitting terminal 1 in response to a retransmission request from another receiving terminal 2 are received.

In step S33, the packet receiving means 2
1 stores the received packet in the packet storage means 22. The packet is stored in the area of the reception buffer corresponding to the sequence number written in the RTP layer of the received packet. For example, as shown in FIG.
On the side, the received packet is stored in a reception buffer area corresponding to the sequence number. If there is a missing packet, the area corresponding to that packet is left empty. When a packet corresponding to the sequence number included in the missing packet list stored in the missing packet list storing means 24 is received, the missing data in the packet storing means 22 is supplemented, and the missing packet is replaced. The corresponding sequence number in the list is deleted and the data in the missing packet list storage means 24 is updated. When a packet retransmitted based on a retransmission request from another receiving terminal 2 is received, that is, when a packet that has already been received is received, the packet is ignored and stored in the packet storage unit 22. Not performed.

In step S34, it is determined whether there is a missing packet. Here, the missing packet determination means 2
According to 3, the sequence number of the received packet is referred to, and if the received packet is discontinuous, it is determined that there is a missing packet, and the process shifts to step S35.

In step S35, the sequence number corresponding to the missing packet list in the missing packet list storage means 24 is written, and the data of the missing packet list is updated. For example, as shown in FIG.
If the third sequence number is missing, this 3
The fifth and fifth sequence numbers are written in the missing packet list.

In step S36, it is determined whether it is time to perform a retransmission request. Here, when the time set in advance in the timer has elapsed, it is determined that the predetermined time for performing the retransmission request has been reached, and the flow shifts to step S37.

In step S37, the information of the number of retransmission requests of the packets registered in the missing packet list in the missing packet list storage means 24 is incremented.

In step S 38, a retransmission request signal is generated for the packet registered in the missing packet list in the missing packet list storage means 24 and transmitted to the transmitting terminal 1. Here, it is configured to transmit the retransmission request count information of the corresponding packet to the transmitting terminal 1 at the same time.

In step S39, it is determined whether or not an end notification signal has been received from transmitting terminal 1. If the termination notification signal has not been received from the transmitting terminal 1, step S3
Then, if it is determined that the end notification signal from the transmitting terminal 1 has been received, the process proceeds to step S40.

In step S40, an end process is executed.

[Multicast Retransmission Processing] As described above, in the case of multicast in which data transfer is performed to a plurality of receiving terminals 2, if a packet loss occurs in a portion close to the transmitting terminal 1, the plurality of receiving terminals 2 become the same. The loss of the packet is detected, and each of them generates a retransmission request signal and transmits it to the transmitting terminal 1. For example, when performing multicasting for 100 terminals, if one packet is lost near the transmitting terminal 1, 10
The zero receiving terminal 2 detects the loss of the packet and transmits a retransmission request signal. The transmitting terminal 1 does not transmit 100 packets in response to the 100 retransmission request signals,
One packet is retransmitted by multicast.

As shown in FIG. 8, when multicasting is performed from the transmitting terminal to the receiving terminal A and the receiving terminal B (the transmitting terminal does not individually transmit data to each of the receiving terminals A and B, but performs the same transmission. The data is transmitted only once. Hereinafter, when retransmission is performed, the same data transmission is transmitted only once.) When the receiving terminal B detects a lost packet, the retransmission request signal (# 1) is transmitted to the transmitting terminal. Based on this, the corresponding packet is retransmitted from the transmitting terminal. The receiving terminal B receives the retransmitted packet and stores it in the corresponding area of the packet storage unit 22. Also, the receiving terminal A has already received this packet and stored it in the packet storage means 22,
Packet storage means 2 ignoring newly received packets
2 is not stored.

As shown in FIG. 9, when a missing packet is detected in receiving terminals A and B, both receiving terminals A and B transmit a retransmission request signal (# 1) for the corresponding packet. Send to terminal. In the transmitting terminal, retransmission request signals (##) from the two receiving terminals A and B
The packet is retransmitted with respect to 1). Since any retransmission request signal has retransmission request number information "# 1" indicating that it is the first retransmission request, one packet is retransmitted by multicast. . The receiving terminals A and B complement the corresponding area of the packet storage means 22 with the packet retransmitted from the transmitting terminal.

As shown in FIG. 10, although the retransmitted packet was successfully received by receiving terminal A,
If the packet is lost again and cannot be received,
After a lapse of a predetermined time, a retransmission request signal (#
Send 2). The transmitting terminal refers to the transmission count information of the transmission history and refers to the retransmission request frequency information (##) of the retransmission request signal.
If 2) is equal to or more than the transmission count information, the packet is retransmitted. Receiving terminal B that has received the retransmitted packet stores the packet in the corresponding area of packet storage means 22 to supplement the data. Further, since the receiving terminal A has already received this packet, it ignores the received packet and does not perform the storing process in the packet storage unit 22.

As described above, even if there are retransmission request signals from a plurality of receiving terminals 2, retransmission processing from the transmitting terminal 1 can be minimized, and congestion of lines and delay time can be reduced.

[Complement of Missing Packet] As described above, when a missing packet is detected on the receiving terminal 2 side, a retransmission request signal is transmitted, and the transmitting terminal 1 retransmits the packet, and receives this. As a result, missing packets are compensated for, so that data reliability and quality can be improved.

However, if the missing packet has not been completely compensated for by the time when the receiving terminal 2 performs the reproduction, the stream data is reproduced without impairing the real-time property of the stream data as much as possible by inserting appropriate data. The configuration is as follows. When the stream data is audio data, silence or noise is inserted, and when the data is image data, the data to be inserted can be configured to use the immediately preceding frame data or the interpolation data of the preceding and following frames. As described above, even when the missing packet is complemented by inserting the data, the sequence number registered in the missing packet list of the missing packet list storage unit 24 is deleted.

[Delay Time] In order to supplement a lost packet by retransmission processing, the receiving terminal 2 has to increase the capacity of the receiving buffer and delay the time until the received stream data is reproduced. There is a need.
This is because missing packets are complemented by retransmission processing within this delay time.

The factors that determine this delay time are:
Traffic, transmission bit rate (packet size,
Packet interval). Among them, the element relates to data quality, and in the case of audio data, relates to sound quality.

By increasing the delay time, more missing packets can be complemented and the fluctuations can be increased. On the other hand, the capacity of the receiving buffer needs to be increased, and the cost and the device configuration are limited. Come. For this reason, it is necessary to set the delay to an optimum value according to the traffic situation and the required data quality.

[Polling] The transmitting terminal 1 transmits a polling request confirmation signal, and the receiving terminal 2 transmits a retransmission request signal in response to the polling request confirmation signal. In this case, the transmitting terminal 1 determines between the steps S14 and S15 in FIG. 5 whether or not the timing for transmitting a request confirmation signal has come. If it is determined that the polling timing has come, the request confirmation signal is sent. A step to send is added. Also, the receiving terminal 2 changes step S36 of FIG. 6 to a step of determining whether or not a request confirmation signal from the transmitting terminal 1 has been received.

It is also possible to transmit a request confirmation signal from another external device. The request confirmation signal can be transmitted using another PC connected to the receiving terminal 2 or a switch operable by a user. Can be transmitted.

[Other Embodiments] In the above embodiment,
Although the case where packet communication is performed using the UDP / IP transmission protocol has been described, it is possible to configure so that data transmission to an unspecified receiving terminal is performed using another transmission protocol. The present invention is not limited to communication but can be applied to a data transmission method in which electronic data is divided and transferred. Further, the present invention is not limited to stream data including audio data and moving image data, but can be configured to simultaneously transmit various electronic data to unspecified receiving terminals using a similar transmission method. It is.

Also, in place of the transmission count information included in the transmission history, retransmission count information indicating the number of retransmissions performed in response to a retransmission request signal from the receiving terminal is stored and included in the retransmission request signal. When the retransmission request count information has a value exceeding the value of the retransmission count information, it is possible to perform a retransmission process.

[0081]

According to the present invention, electronic data can be transmitted to a plurality of receiving terminals in real time, and a retransmission request signal for a divided data corresponding to a sequence number that could not be received by the receiving terminal. Accept
Because it is configured to retransmit the divided data,
It is possible to improve the reliability of data transfer. On the transmitting terminal side, the transmission count information of each divided data is stored in the transmission history, and the retransmission request count information transmitted from the receiving terminal is compared with the transmission count information of the corresponding divided data. Due to the retransmission process of the divided data,
Even if retransmission requests for the same divided data are received from a plurality of receiving terminals, it is possible to prevent retransmission from being performed repeatedly. In addition, the receiving terminal records the number of retransmission requests for the divided data corresponding to the missing sequence number as retransmission request number information, even if there is divided data that could not be received. By retrying multiple times, the missing divided data can be compensated,
It is possible to maintain high quality of received data. Further, since the receiving terminal side temporarily stores each divided data in the storage unit based on the sequence number, there is a slight delay from the data transmission from the transmitting terminal. By starting, the real-time property is not significantly impaired.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a schematic configuration of the present invention.

FIG. 2 is a functional block diagram of a transmission terminal.

FIG. 3 is a functional block diagram of a packet transmission unit.

FIG. 4 is a functional block diagram of a receiving terminal.

FIG. 5 is a flowchart showing the operation of the transmitting terminal.

FIG. 6 is a flowchart showing the operation of the receiving terminal.

FIG. 7 is an explanatory diagram of a packet retransmission process.

FIG. 8 is an explanatory diagram of retransmission processing in multicast.

FIG. 9 is an explanatory diagram of retransmission processing in multicast.

FIG. 10 is an explanatory diagram of retransmission processing in multicast.

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Claims (11)

[Claims] An electronic data transmission method for transmitting electronic data from a transmitting terminal to an unspecified receiving terminal, the method comprising: dividing the electronic data into a plurality of divided data; Transmitting from the transmitting terminal to the receiving terminal, recording a transmission history including transmission count information of each divided data transmitted from the transmitting terminal, and storing each divided data received by the receiving terminal based on its sequence number. Storing in the means, and determining whether there is a missing sequence number from the sequence number of each divided data received at the receiving terminal, and if there is a missing sequence number, the retransmission request number information of the corresponding divided data is determined. Increment and record, and a retransmission request signal of the corresponding divided data is transmitted from the receiving terminal together with the retransmission request number information. Transmitting to the terminal, determining whether to perform retransmission based on the retransmission request number information included in the retransmission request signal received by the transmitting terminal and the transmission number information of the corresponding divided data in the transmission history. A step of, when retransmitting, incrementing the transmission count information of the corresponding divided data to update the transmission history and retransmitting the corresponding divided data. 2. The data transmission protocol is UDP / IP (User D
2. An atagram protocol (Internet protocol), wherein the divided data is a packet.
Transmission method of electronic data described in 1. 3. The electronic data transmission method according to claim 1, wherein the electronic data is stream data including moving image data or audio data. 4. An electronic data transmitting apparatus for transmitting electronic data to an unspecified receiving terminal, comprising: dividing the electronic data into a plurality of divided data; Data transmitting means for transmitting to a receiving terminal; transmission history storing means for storing a transmission history including transmission count information of each divided data transmitted by the data transmitting means; a retransmission request signal for the divided data that could not be received by the receiving terminal The retransmission request receiving unit receiving the retransmission request signal of the divided data together with retransmission request number information indicating the number of times transmitted from the receiving terminal, and the number of retransmission request information received by the retransmission request receiving unit,
A retransmission determining unit that compares the transmission count information of the corresponding divided data included in the transmission history stored in the transmission history storage unit to determine whether to retransmit the corresponding divided data; Data for causing the data transmission means to retransmit the corresponding divided data based on the determination result of the determination means, incrementing the transmission count information of the corresponding divided data, and updating the transmission history stored in the transmission history storage means Retransmission means; and an electronic data transmission device comprising: 5. The data transmission means according to claim 1, wherein said data transmission means comprises a UDP / IP (User Dat
The electronic data transmitting apparatus according to claim 4, wherein the divided packets are sequentially transmitted to an unspecified receiving terminal using an agram Protocol / Internet Protocol (agram Protocol) transmission protocol. 6. The electronic data transmitting apparatus according to claim 4, wherein said electronic data is stream data including moving image data or audio data. 7. An electronic data receiving apparatus for receiving electronic data transmitted to an unspecified receiving terminal, comprising: a plurality of divided data divided by a sequence number indicating continuity thereof; A data receiving unit that receives electronic data transmitted from the data receiving unit; a data storage unit that stores each divided data received by the data receiving unit based on the sequence number; and a sequence of each divided data that is received by the data receiving unit. Missing data determining means for determining the presence or absence of a sequence number missing from the number; retransmission indicating the number of times the sequence number determined to be missing by the missing data determining means and the number of times a retransmission request signal of the corresponding divided data has been transmitted; A missing data list storing means for storing request count information; and a missing data list storing means for storing the missing data list storing means. Increments the number of retransmission requests information of the divided data corresponding to the sequence number, and retransmission request means for transmitting to the transmitting terminal together with the retransmission request signal of the corresponding divided data receiving apparatus of an electronic data comprising. 8. The data receiving means according to claim 1, wherein said data receiving means comprises a UDP / IP (User Dat
The electronic data receiving device according to claim 7, wherein a packet transmitted to an unspecified receiving terminal is sequentially received using an agram Protocol / Internet Protocol (agram Protocol) transmission protocol. 9. The electronic data receiving apparatus according to claim 7, wherein the electronic data is stream data including moving image data or audio data. 10. The retransmission request unit reads a sequence number stored in the missing data list storage unit at predetermined time intervals and transmits a retransmission request signal.
The electronic data receiving device according to any one of the above. 11. The electronic data receiving apparatus according to claim 7, wherein said retransmission request means transmits a retransmission request signal based on a request confirmation signal by polling from a transmitting terminal or an external device. .