JP2004254127A - Data transmission method, its program and its apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a data transmission method or the like for enabling precise error control without lowering data transmission efficiency. <P>SOLUTION: The data transmission method uses a forward error control method. The data transmission method includes a negative acknowledge receiving step for receiving, from a receiving apparatus 2, the negative acknowledge that denotes existence of loss packets impossible to be decoded even by the forward error control method, a redundant data amount regulating step for regulating a redundant data amount depending on the receiving state of the negative acknowledge (or identification information of the loss packets contained in the negative acknowledge), and a transmission rate control step for regulating the limiting number of the packets transmitted per hour depending on the redundant data amount that are regulated in the redundant data amount regulating step. Further, a step for regulating shuffling spans depending on the receiving state of the negative acknowledge and a packet size regulating step for regulating packet sizes depending on the receiving state of the negative acknowledge are included therein. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a data transmission method, a data transmission program, and a data transmission device.
[0002]
[Prior art]
2. Description of the Related Art In high-speed data communication such as streaming, a data communication method with good data transmission efficiency and accurate error control is required. As a conventional technique developed for such a purpose, for example, there is a technique disclosed in JP-A-2002-330118 (Patent Document 1). Patent Literature 1 discloses a data distribution control method that determines the redundancy of FEC encoding in the next and subsequent data transmissions according to reception failure block information returned from a reception computer.
[0003]
In addition, as a product on which the reliable multicast is mounted, there are a DigitalFuntain server of DigitalFuntain, RMTPv3 of NTT, and the like.
[0004]
[Patent Document 1] JP-A-2002-330118
[0005]
[Patent Document 2] JP-A-2001-308895
[0006]
[Problems to be solved by the invention]
However, the Digital Foundation server of Digital Foundation and the RMTPv3 of NTT have a problem that the data is transmitted without responding to the fluctuation of the error rate, so that the transmission efficiency is deteriorated.
[0007]
Further, the data distribution control method of Patent Document 1 has a problem that when the redundancy is increased, there is a possibility that congestion occurs in the transmission path and transmission efficiency is deteriorated.
[0008]
The present invention has been made to solve the above problem, and has as its object to provide a data transmission method or the like that enables appropriate error control without deteriorating data transmission efficiency.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a data transmission method, a data transmission program, and a data transmission device according to the present invention provide a forward error for grouping a plurality of packets and correcting errors in data in the group from redundant data corresponding to the group. Using the correction method, from the receiving device of the transmission data, indicates that there is a lost packet that can not be decoded even by the forward error correction method, the reception status of the negative response in the negative response receiving step or the identification information of the lost packet included in the negative response Accordingly, the amount of redundant data added to the transmitted original data is adjusted, and the limit number of packets transmitted per time is adjusted according to the amount of redundant data adjusted in the redundant data amount adjusting step. It is characterized by the following.
[0010]
The redundant data amount adjusting means can adjust the redundant data amount so as to enable appropriate error control according to a fluctuating error occurrence state in the transmission path. Further, the transmission rate control means can control the packet transmission rate so as to maintain the data transmission efficiency according to the adjusted amount of redundant data.
[0011]
In order to achieve the above object, a data transmission method, a data transmission program, and a data transmission device according to the present invention provide a forward error for grouping a plurality of packets and correcting errors in data in the group from redundant data corresponding to the group. Using a correction method, a plurality of groups are gathered to form a shuffling group, the arrangement of the packets included in the shuffling group is rearranged, and from the transmission data receiving apparatus, there is a lost packet that cannot be decoded even by the forward error correction method. The number of packets included in one shuffling group is adjusted in the shuffling step according to the reception status of the negative acknowledgment in the negative acknowledgment receiving step or the identification information of the lost packet included in the negative acknowledgment.
[0012]
The shuffling span adjusting means can adjust the shuffling span (the number of packets included in one shuffling group) so that appropriate error control can be performed according to a fluctuating error occurrence state in the transmission path. Further, the shuffling span can be adjusted without deteriorating the data transmission efficiency.
[0013]
In order to achieve the above object, a data transmission method, a data transmission program, and a data transmission device according to the present invention provide a forward error for grouping a plurality of packets and correcting errors in data in the group from redundant data corresponding to the group. Using the correction method, from the receiving device of the transmission data, receives a negative response indicating that there is a lost packet that can not be decoded even by the forward error correction method, the reception status of the negative response or identification information of the lost packet included in the negative response It is characterized in that the packet size is adjusted accordingly.
[0014]
The packet size adjusting means can adjust the packet size so that appropriate error control can be performed according to a fluctuating error occurrence state in the transmission path. The adjustment of the packet size can be performed without deteriorating the data transmission efficiency.
[0015]
According to the data transmission method, the data transmission program and the data transmission device of the present invention, the negative acknowledgment includes the identification information of the lost packet that cannot be decoded, and the negative acknowledgment receiving means sends the negative acknowledgment including the same identification information within a predetermined time. When the transmission data is received from a plurality of receiving devices that receive the transmission data via the same relay device, it is preferable that a packet corresponding to the identification information be retransmitted to these receiving devices in a multicast manner.
[0016]
The data transmission efficiency can be further improved by reducing the number of packets transmitted in the upstream part of the transmission path.
[0017]
The data transmission method, data transmission program, and data transmission device of the present invention further divide a packet to be transmitted into a plurality of subpackets, group the plurality of subpackets, add redundant data, and arrange the subpacket arrangement. It is preferred to change.
[0018]
Further, since the sub-packets are shuffled, the robustness against the burst error is enhanced.
[0019]
INDUSTRIAL APPLICABILITY The data transmission method, data transmission program and data transmission apparatus of the present invention are applied to simultaneous transmission of program data of a large number of channels, transmit program data in a predetermined transmission order in each channel, and use the remaining data not to be used for transmission of program data. When a band occurs, it is preferable to use the extra band to increase the transmission speed of program data being transmitted or to start transmission of untransmitted program data. Thus, the transmission path can be used without waste.
[0020]
In a data transmission method according to the present invention, a group in the forward error correction method includes a plurality of data packets including original data to be transmitted, and a parity packet including redundant data for the original data. It is preferable that when all the data packets belonging to are received, the decoding calculation using the parity packet is not performed.
[0021]
Since the redundant data is included in the parity packet different from the data packet, the original data can be restored only by aligning the data packet when there is no loss of the data packet. This can reduce the amount of calculation processing in the receiving device.
[0022]
In the data transmission method of the present invention, a plurality of receiving devices are divided into a master client and a slave client, the master client transmits a negative response to the transmission source of the transmission data and the slave client, and the slave client does not receive the negative response. It is preferable to transmit a negative acknowledgment to the transmission source of the transmission data only when the transmission has been performed. By reducing the number of negative acknowledgments transmitted to the source of the transmission data, it is possible to prevent congestion on the downlink transmission path.
[0023]
In the data transmission method of the present invention, it is preferable that, in the receiving device, the received data is stored in the storage device. As a result, data errors during data reproduction can be reduced.
[0024]
The data transmission method of the present invention is preferably applied to data transmission via wireless communication. In wireless communication, an error situation in a transmission path fluctuates particularly strongly due to the influence of weather, atmospheric density distribution, and the like. Therefore, the present invention that can cope with a fluctuating error occurrence situation in a transmission path is preferably applied to data transmission via wireless communication.
[0025]
The data transmission method of the present invention is preferably applied to a data transmission system that transfers data received by a receiving device to a storage device mounted on a passenger car by wireless communication. As a result, it is possible to provide broadband data transmission to passenger cars that cannot use a wired cable.
[0026]
The data transmission method of the present invention is applied to data transmission composed of a plurality of layers of networks, and the data transmission method according to any one of claims 1 to 11 is preferably performed in each layer of the networks. . Since the data transmission method of the present invention is performed in each layer, the accuracy of error control and the transmission efficiency are further improved.
[0027]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of a data transmission method, a data transmission program, and a data transmission device of the present invention will be described in detail with reference to the accompanying drawings.
[0028]
(1st Embodiment)
FIG. 1 is a functional configuration diagram of an IP multicast transmission system A to which the data transmission method according to the present embodiment is applied. A plurality of multimedia files are stored in the storage unit 12 of the data transmission device 1, and the multimedia files are multicast-transmitted to a specific number of receiving devices 2 via the Internet. In the IP multicast transmission system A, the receiver 2 performs error correction using a forward error correction method (FEC; Forward Error Correction). When error correction using FEC is not possible, a lost packet is retransmitted based on a NACK signal (negative acknowledgment) transmitted from the receiving device 2.
[0029]
The data transmission device 1 includes, as functional components, a negative acknowledgment receiving unit 102, a packetizing unit 104, a packet size adjusting unit 106, a redundant data adding unit 108, a redundant data amount adjusting unit 110, a shuffling unit 112, and a shuffling span adjusting unit. 114, a transmission rate control unit 116, a packet transmission unit 118, and an error resilience unit 120.
[0030]
Negative response receiving section 102 receives a NACK signal transmitted from receiving apparatus 2. The packetizing unit 104 reads a media file (original data) being distributed from the storage unit 12 and forms a data packet. The packet size adjustment unit 106 adjusts the size of the packet based on the reception state of the NACK signal or the transmission sequence number of the lost packet included in the NACK signal. The redundant data adding unit 108 forms a FEC group by collecting a plurality of data packets, and adds a parity packet (redundant data) corresponding to the FEC group to the original data. The redundant data amount adjustment unit 110 adjusts the amount of redundant data with respect to the original data by increasing or decreasing the number of data packets included in the FEC group based on the reception state of the NACK signal or the transmission sequence number of the lost packet included in the NACK signal. adjust. The shuffling unit 112 collects a plurality of FEC groups to form a shuffling group, and shuffles the packets belonging to the shuffling group (rearranging the arrangement, that is, changing the transmission order). The shuffling span adjustment unit 114 increases or decreases the number of FEC groups constituting the shuffling group, that is, the number of packets belonging to the shuffling group. The transmission rate control unit 116 adjusts the packet transmission rate limit value based on the reception state of the NACK signal or the transmission sequence number of the lost packet included in the NACK signal. Packet transmitting section 118 transmits a packet based on transmission parameters determined by packet size adjusting section 106, redundant data amount adjusting section 110, shuffling span adjusting section 114, and transmission rate control section 116. Further, packet transmitting section 118 transmits the packet requested to be retransmitted by the NACK signal by the unicast method or the multicast method.
[0031]
The error resilience unit 120 forms sub-packets obtained by subdividing the data packet and the parity packet as necessary, adds a sub-parity packet to these sub-packets, and generates a sub-packet and a sub-packet in the FEC group or the shuffling group. Rearrange the arrangement of sub-parity packets. In this case, the sub-packets that are further subdivided are shuffled, so that the robustness against burst errors is enhanced.
[0032]
FIG. 2 is a flowchart showing a procedure for transmitting and receiving a multimedia file in the IP multicast transmission system A. A procedure for transmitting and receiving a multimedia file in the IP multicast transmission system A will be described with reference to FIG.
[0033]
When the transmission parameters are determined in the transmission parameter determination step (S202) (details of the transmission parameter determination step will be described later), the packetizing unit 104 reads the media file being distributed from the storage unit 12, and in the transmission parameter determination step. The read data is packetized based on the determined packet size to form a data packet (S204).
[0034]
The redundant data adding unit 108 forms the FEC group by collecting the number of data packets determined in the transmission parameter determining step, forms a parity packet corresponding to the FEC group, and adds the parity packet to the FEC group (S206). 3A and 3B are explanatory diagrams of a process of forming a parity packet. Here, an outline of the parity packet forming process will be described with reference to FIGS. 3A and 3B. As shown in FIG. 3A, an FEC group composed of data packets 1 (data symbols: A1, B1... I1) to data packets 9 (data symbols: A9, B9... I9) is divided into blocks. Parity 1 (X1, X2... X3) and parity 2 (Y1, Y2... Y3) are obtained by calculating exclusive OR in the vertical and horizontal directions of the blocked FEC group. For example, in the horizontal direction, X1 is calculated by the following logical expression (1).
X1 = A1 + B1 + C1 + D1 + E1 + F1 + G1 + H1 + I1 (1)
Here, + represents an exclusive OR (XOR).
In the vertical direction, Y1 is calculated by the following logical expression (2).
Y1 = A1 + A2 + A3 + A4 + A5 + A6 + A7 + A8 + A9 (2)
Here, + represents an exclusive OR (XOR).
As shown in FIG. 3B, the parity packets 1 and 2 independent of the data packets are obtained by decomposing the blocks.
[0035]
The shuffling unit 112 forms a shuffling group by collecting the number of FEC groups determined in the transmission parameter determining step, and rearranges the arrangement of the packets belonging to the shuffling group (S208).
[0036]
The packet transmission unit 118 multicast-transmits the packet according to the transmission sequence number based on the packet transmission speed limit value (the maximum number of packets transmitted per time) determined in the transmission parameter determination step (S210). As an example of a specific packet transmission method, the transmission speed is gradually increased from the initial transmission speed while confirming that there is no congestion in the transmission path, and when the limit value is reached, the process of returning to the initial transmission speed again is repeated. There is a way. As a method of detecting the congestion of the transmission path, measurement of RTT (Round Trip Time) can be considered.
[0037]
When the receiving device 2 receives the packet (S212), it checks from the transmission sequence number of the packet whether there is a packet lost for each shuffling group (S214). If there is no packet loss, the data packets belonging to the shuffling group are sorted without performing deshuffling and decoding (S222).
[0038]
If there is a packet loss, deshuffling is performed to reconfigure the FEC group (S216). Further, a decoding operation of the lost packet is performed from the data packet and the parity packet transmitted for the FEC group having the packet loss (S218), and it is confirmed whether or not the lost packet can be restored (S220). When a lost packet can be restored by this decoding operation, the packets are aligned (S222).
[0039]
If the decoding operation cannot be performed because the number of lost packets in the FEC group is large, a NACK signal (retransmission request for lost packets) is transmitted from the receiving device 2 to the data transmission device 1 (S224).
[0040]
FIG. 4 is an explanatory diagram of a process in which a lost packet is retransmitted. The outline of the process of retransmitting a lost packet will be described with reference to FIG. However, in the FEC of FIG. 4, it is assumed that a parity of redundancy for decoding one data packet is added. In case 1 in FIG. 4, since the data packets 5, 6 and the parity packet 9 have been lost, a NACK signal requesting their retransmission is returned. In response to this, all the requested packets are retransmitted and received, so that the packets are aligned without performing the decoding operation.
[0041]
Note that retransmission of a packet is performed by a multicast method when retransmission requests for packets having the same sequence number are received from a plurality of receiving devices 2 that receive data via the same relay device. That is, one packet is retransmitted to the relay device, and the relay device duplicates the retransmitted packet and transfers it to each receiving device 2. Otherwise, it is retransmitted by the unicast method. For this reason, the data transmission efficiency can be improved by reducing the number of packets transmitted in the upstream part of the transmission path.
[0042]
In case 2 in FIG. 4, since the data packets 5, 6 and the parity packet 9 have been lost, a NACK signal requesting their retransmission is returned. In response to this, since packets other than the data packet 6 have been retransmitted and received, the data packet 6 is decoded by the decoding operation.
[0043]
In case 3 in FIG. 4, since the data packets 5, 6 and the parity packet 9 have been lost, a NACK signal requesting their retransmission is returned. In response, only data packet 5 was retransmitted and received. Since the parity packet 9 was not retransmitted or received, the remaining data packet 6 could not be decoded. Therefore, the failure in the reception and decoding of the data packet 6 is registered in the transmission source data. When a failure is registered, the program (program) may not be displayed when the VOD menu is generated. Further, since the failure information of all the clients is registered, it is possible to transfer the information to a client that is close in network distance.
[0044]
FIG. 5 is a flowchart showing a processing procedure in the transmission parameter determination step. The processing procedure in the transmission parameter determination step will be described in detail with reference to FIG.
[0045]
The negative acknowledgment receiving unit 102 receives the NACK signal (S502), and detects the packet loss rate and the occurrence of the burst error from the reception state of the NACK signal or the transmission sequence number included in the NACK signal (S504). For example, the packet loss rate can be measured from the frequency of receiving a NACK signal from a specific receiving device 2 per time. Further, the burst error (short interruption) time can be known from the length of time during which the NACK signal is received within a predetermined interval.
[0046]
Further, the burst error time can be known from the transmission sequence number. FIG. 6 is a diagram illustrating a relationship between a burst error and a transmission sequence number. The burst time when one Ethernet frame (1500 bytes = 12,000 bits) is lost in a 100 Mbps band is 120 μsec or less.
1 / (100,000,000 bits / sec) × 12,000 bits = 120 μsec
According to FIG. 6, it can be seen that a bucket loss has occurred in the backbone common to the receivers 2 of the client numbers 1 to 10 in the transmission path during transmission of the transmission sequence number 8. When this is converted into a disconnection time, it is 120 μsec or less, which indicates that this packet loss is caused by a random error.
[0047]
Also, it can be seen that, during the transmission of the transmission sequence numbers 12 to 20, a burst of more than 960 μsec and equal to or less than 1180 μsec occurred in the branch portion leading to the receiver 2 of the client number 2 in the transmission path. If the lost packet cannot be decoded, the packet is retransmitted to the receiving device 2 of the client number 2 by the unicast method.
[0048]
Further, it can be seen that, during transmission of the transmission sequence numbers 25 to 33, a burst longer than 960 μsec and equal to or less than 1180 μsec occurred in the main unit common to the receivers 2 of the client numbers 1 to 10 in the transmission path. If the lost packet cannot be decoded, the packet is retransmitted to the receiving devices 2 of the client numbers 1 to 10 by the multicast method.
[0049]
The packet size adjustment unit 106 calculates a packet size sufficient to cover the packet loss rate and the burst error detected in S504 (S506).
[0050]
The redundant data amount adjustment unit 110 calculates a redundant data amount sufficient to cover the packet loss rate and the burst error detected in S504 (S508).
[0051]
The shuffling span adjustment unit 114 calculates a shuffling span sufficient to cover the packet loss rate and the burst error detected in S504 (S508).
[0052]
The transmission rate control unit 116 calculates the limit value of the packet transmission rate at a level that does not cause congestion on the transmission path, based on the amount of redundant data determined in S508 (S512).
[0053]
As shown in FIG. 1, when the receiving device 2 is composed of a master client 2m and a subordinate slave client 2s, only the master client 2m transmits a NACK signal as a method of transmitting a NACK signal. In 2s, only when the NACK signal is not received from the master client 2m, it is conceivable that the NACK signal is transmitted at a staggered time such as when playing a media file. According to this method, the amount of the NACK signal transmitted to the transmission device 1 is reduced, so that congestion on the uplink transmission path can be prevented.
[0054]
FIG. 7 is a conceptual diagram showing how a failure occurrence location is specified in the IP multicast transmission system A. When the NACK signal from the receiving device 2 does not return, the occurrence and location of the transmission failure can be confirmed.
[0055]
Next, the operation and effect of the IP multicast transmission system A will be described. The redundant data amount adjustment unit 110 can adjust the redundant data amount so that appropriate error control can be performed according to a fluctuating error occurrence state in the transmission path. Further, the transmission rate control section 116 can control the packet transmission rate so as to maintain the data transmission efficiency according to the amount of redundant data to be adjusted.
[0056]
The shuffling span adjustment section 114 can adjust the shuffling span (the number of packets included in one shuffling group) so that appropriate error control can be performed according to the fluctuating error occurrence state in the transmission path. Further, the shuffling span can be adjusted without deteriorating the data transmission efficiency.
[0057]
The packet size adjustment unit 106 can adjust the packet size so that appropriate error control can be performed according to a fluctuating error occurrence state in the transmission path. The adjustment of the packet size can be performed without deteriorating the data transmission efficiency.
[0058]
Further, in the present embodiment, since the redundant data is included in the parity packet different from the data packet, when there is no loss of the data packet, the original data can be restored only by aligning the data packet. This can reduce the amount of calculation processing in the receiving device.
[0059]
(2nd Embodiment)
An embodiment for distributing a multi-channel program using the IP multicast transmission system A (multi-channel program distribution system B) will be described. Note that the multi-channel program distribution system B is a storage type broadcasting system in which a distributed program is temporarily stored in a storage device on the receiving side, and is reproduced after the distribution is completed.
[0060]
FIG. 8 is a diagram showing an example of a distribution plan in the multi-channel program distribution system B. FIG. 9 is a diagram illustrating bands used for each channel in each time zone. As shown in FIG. 8, in the multi-channel program distribution system B, a plurality of channels are provided for each category, and the length, size (data amount), transmission speed (bit rate), application bandwidth, and predicted length of each channel are provided. Delivery time (temporary delivery time), scheduled delivery time, transmission priority (priority), and the like are set in advance.
[0061]
However, the distribution time actually required may be shorter than the provisional distribution time due to congestion and error occurrence on the transmission path. In such a case, there is a surplus band not used for any channel. In this case, the packet transmission unit 118 increases the transmission speed of a program with a higher priority using the surplus bandwidth, or advances and distributes the next program for a channel whose distribution has been completed earlier than predicted. Thus, the transmission path can be used without waste. In FIG. 9, the transmission speed of the high-priority home theater movie material “HDTV” (26) is increased.
[0062]
(Third embodiment)
FIG. 10 is a functional configuration diagram of the data transmission program 40 of the present embodiment. A data transmission program 40 is recorded in a storage area of the recording medium 4. The data transmission program 40 includes a negative response receiving module 402, a packetizing module 404, a packet size adjusting module 406, a redundant data adding module 408, a redundant data amount adjusting module 410, a shuffling module 412, and a shuffling span adjusting module 414 as functional components. , A transmission rate control module 416, a packet transmission module 418, and an error resilience module 420, which are executed by the computer 6 to execute the negative response receiving unit 102, the packetizing unit 104, and the packet in the first and second embodiments. Size adjusting unit 106, redundant data adding unit 108, redundant data amount adjusting unit 110, shuffling unit 112, shuffling span adjusting unit 114, transmission speed control unit 116, packet transmitting unit 1. Functions similarly to 8 and error tolerance section 120.
[0063]
(Fourth embodiment)
FIG. 11 is a schematic diagram of a storage broadcast system using a cable TV network. At present, a broadband environment for homes using a high-speed wireless LAN such as an ADSL “xDSL” using a telephone line, FTTH, CATV Internet and an optical wireless LAN has been established. Even if you try to realize on-demand high-definition streaming such as high-definition video equivalent to a movie using these environments, the best-effort network may cause block-like images due to network congestion. There is a situation where images are interrupted. When the data transmission method of the present invention as shown in the first and second embodiments is applied to a storage and broadcast system, error-free video data is sent in advance from a distribution server to a client home server or STB (set-top box). By storing the data in a storage device such as a hard disk and using a menu generated by the client to view the video on video-on-demand (VOD), it is possible to view a high-quality video without any block noise.
[0064]
(Fifth embodiment)
FIG. 12 is a conceptual diagram of an embodiment in which an area of a cable television station is extended using an optical wireless communication system, and FIG. 13 is a block diagram thereof. For example, there is a place where a cable cannot be drawn due to permission and permission at a place across a road, a river, and a track, but the area of a cable TV station can be extended to a place where a cable cannot be drawn using wireless communication. In particular, the current cable station has an IP communication network generally called cable TV Internet, and the IP communication network can be expanded by using a high-speed wireless communication system such as an optical wireless LAN as the last stage.
[0065]
In an optical wireless communication system, the state of error occurrence on a transmission line fluctuates drastically under the influence of weather, spot dancing due to changes in the atmospheric density distribution, and the like. However, by applying the data transmission method of the present invention as shown in the first and second embodiments, it is possible to realize error control according to an error occurrence situation that fluctuates greatly while maintaining data transmission efficiency.
[0066]
(Sixth embodiment)
FIG. 14 is a conceptual diagram of an embodiment for realizing music distribution using an in-vehicle information terminal. Although each home has a broadband line, the content is distributed to an in-car storage type content player without a cable by an optical wireless LAN system.
[0067]
In an optical wireless communication system, the state of error occurrence on a transmission line fluctuates drastically under the influence of weather, spot dancing due to changes in the atmospheric density distribution, and the like. However, by applying the data transmission method of the present invention as shown in the first and second embodiments, it is possible to maintain not only high-quality music data but also data and local data for use in a navigation system while maintaining data transmission efficiency. Traffic information can be delivered without errors.
[0068]
(Seventh embodiment)
The above-described data transmission method, in particular, a data transmission method of changing transmission parameters according to an error state of a transmission path, and a method of retransmitting a packet by a multicast method or a unicast method according to the number of receiving apparatuses requesting packet retransmission Is performed in each layer of the multi-layer network, the data transmission efficiency and reliability can be further improved.
[0069]
FIG. 15 is a conceptual diagram of an embodiment in which the data transmission method of the present invention is applied to a regional IX service all over the world via the Internet. The data transmission method of the present invention as shown in the first and second embodiments can be applied to each layer of the Internet content distribution network and the regional content distribution network.
[0070]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a data transmission method or the like that enables appropriate error control without deteriorating data transmission efficiency.
[Brief description of the drawings]
FIG. 1 is a functional configuration diagram of an IP multicast transmission system A to which a data transmission method according to a first embodiment is applied.
FIG. 2 is a flowchart illustrating a procedure for transmitting and receiving a multimedia file in the IP multicast transmission system A;
FIG. 3 is an explanatory diagram of a process of forming a parity packet.
FIG. 4 is an explanatory diagram of a process in which a lost packet is retransmitted.
FIG. 5 is a flowchart illustrating a processing procedure in a transmission parameter determining step;
FIG. 6 is a diagram illustrating a relationship between a burst error and a transmission sequence number.
FIG. 7 is a conceptual diagram showing a manner in which a failure location is specified in the IP multicast transmission system A.
FIG. 8 is a diagram illustrating an example of a distribution plan in the multi-channel program distribution system B;
FIG. 9 is a diagram illustrating bands used for each channel in each time zone.
FIG. 10 is a functional configuration diagram of a data transmission program 40.
FIG. 11 is a schematic diagram of a storage broadcast system using a cable TV network.
FIG. 12 is a conceptual diagram of an embodiment in which an area of a cable television station is extended using an optical wireless communication system.
FIG. 13 is a block diagram of an embodiment for expanding an area of a cable television station using an optical wireless communication system.
FIG. 14 is a conceptual diagram of an embodiment for realizing music distribution using an in-vehicle information terminal.
FIG. 15 is a conceptual diagram of an embodiment in which the data transmission method of the present invention is applied to regional IX services all over the world via the Internet.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Data transmission device, 12 ... Storage part, 102 ... Negative response receiving part, 104 ... Packetization part, 106 ... Packet size adjustment part, 108 ... Redundant data addition part 110: redundant data amount adjustment unit, 112: shuffling unit, 114: shuffling span adjustment unit, 116: transmission rate control unit, 118: packet transmission unit, 120: error tolerance Unit 2, receiving apparatus, 4 recording medium, 6 computer, 40 data transmission program, 402 negative response receiving module, 404 packetizing module, 406. Packet size adjustment module, 408: redundant data addition module, 410: redundant data amount adjustment module, 412: shuffling module, 4 4 ... shuffling span adjustment module, 416 ... transmission rate control module, 418 ... packet transmission module, 420 ... error tolerance module.

Claims (19)

A data transmission method using a forward error correction method of grouping a plurality of packets and performing error correction of data in the group from redundant data corresponding to the group,
From a transmission data receiving device, a negative acknowledgment receiving step of receiving a negative acknowledgment indicating that there is a lost packet that cannot be decoded even by the forward error correction method,
A redundant data amount adjusting step of adjusting an amount of redundant data added to original data to be transmitted according to a reception status of the negative response in the negative response receiving step or identification information of the lost packet included in the negative response When,
A transmission rate control step of adjusting a limit number of packets transmitted per time according to the amount of redundant data adjusted in the redundant data amount adjustment step. A data transmission method using a forward error correction method of grouping a plurality of packets and performing error correction of data in the group from redundant data corresponding to the group,
A shuffling step of collecting a plurality of the groups to form a shuffling group and rearranging the arrangement of packets included in the shuffling group;
From a transmission data receiving device, a negative acknowledgment receiving step of receiving a negative acknowledgment indicating that there is a lost packet that cannot be decoded even by the forward error correction method,
A shuffling span adjusting step of adjusting the number of packets included in one shuffling group in the shuffling step according to the reception status of the negative acknowledgment in the negative acknowledgment receiving step or the identification information of the lost packet included in the negative acknowledgment. And a data transmission method. A data transmission method using a forward error correction method of grouping a plurality of packets and performing error correction of data in the group from redundant data corresponding to the group,
From a transmission data receiving device, a negative acknowledgment receiving step of receiving a negative acknowledgment indicating that there is a lost packet that cannot be decoded even by the forward error correction method,
A packet size adjusting step of adjusting a packet size according to a reception status of the negative response in the negative response receiving step or identification information of the lost packet included in the negative response. The negative response includes identification information of a lost packet that cannot be decoded,
When the negative acknowledgment receiving means receives the negative acknowledgment including the same identification information within a predetermined time from a plurality of receiving devices receiving transmission data via the same relay device, multicasting is performed on these receiving devices. 4. The data transmission method according to claim 1, wherein a packet corresponding to the identification information is retransmitted in a system. An error resilience step of further dividing the transmitted packet into a plurality of subpackets, grouping the plurality of subpackets, adding redundant data, and rearranging the arrangement of the subpackets. Item 3. The data transmission method according to Item 2. It is applied to simultaneous transmission of program data of many channels,
When program data is transmitted in a predetermined transmission order in each channel and a surplus band not used for transmission of the program data occurs, the transmission speed of the program data being transmitted is increased by using the surplus band or untransmitted program data is used. 4. The data transmission method according to claim 1, wherein transmission of the data is started. The group in the forward error correction method is configured to include a plurality of data packets including original data to be transmitted, and a parity packet including redundant data for the original data,
The data according to any one of claims 1 to 3, wherein a decoding calculation using the parity packet is not performed when all data packets belonging to the group are received by the receiving device. Transmission method. The plurality of receiving devices are divided into a master client and a slave client,
The master client sends a negative response to the transmission data source and the slave client,
4. The data transmission method according to claim 1, wherein a negative response is transmitted to a transmission data source only when the slave client does not receive the negative response. The data transmission method according to claim 1, wherein the receiving device stores the received data in a storage device. The data transmission method according to any one of claims 1 to 3, wherein the method is applied to data transmission via wireless communication. The data transmission method according to claim 9, wherein the data transmission method is applied to a data transmission system that transfers data received by the receiving device to a storage device mounted on a passenger car by wireless communication. Applied to data transmission consisting of multiple layers of networks,
12. A data transmission method, wherein the data transmission method according to claim 1 is performed in a network of each layer. A data transmission program for causing a computer to execute the data transmission method according to any one of claims 1 to 6. A data transmission apparatus that performs a forward error correction method of grouping a plurality of packets and performing error correction of data in the group from redundant data corresponding to the group,
From the receiving device of the transmission data, a negative response receiving means for receiving a negative response indicating that there is a lost packet that cannot be decoded by the forward error correction method,
Redundant data amount adjusting means for adjusting the amount of redundant data added to the original data to be transmitted in accordance with the reception status of the negative response by the negative response receiving means or the identification information of the lost packet included in the negative response When,
A data transmission device comprising: a transmission rate control unit that adjusts a limit number of packets transmitted per time in accordance with the amount of redundant data adjusted by the redundant data amount adjustment unit. A data transmission apparatus that performs a forward error correction method of grouping a plurality of packets and performing error correction of data in the group from redundant data corresponding to the group,
Shuffling means for collecting a plurality of the groups to form a shuffling group, and rearranging the arrangement of packets included in the shuffling group;
From the receiving device of the transmission data, a negative response receiving means for receiving a negative response indicating that there is a lost packet that cannot be decoded by the forward error correction method,
A shuffling span adjusting unit that adjusts the number of packets included in one shuffling group according to the reception status of the negative response by the negative response receiving unit or the identification information of the lost packet included in the negative response. A data transmission device characterized by the above-mentioned. A data transmission apparatus that performs a forward error correction method of grouping a plurality of packets and performing error correction of data in the group from redundant data corresponding to the group,
From the receiving device of the transmission data, a negative response receiving means for receiving a negative response indicating that there is a lost packet that cannot be decoded by the forward error correction method,
A data transmission apparatus comprising: a packet size adjusting unit that adjusts a packet size according to a reception status of the negative response by the negative response receiving unit or identification information of the lost packet included in the negative response. The negative acknowledgment includes identification information of a lost packet that cannot be decoded, and the negative acknowledgment receiving means receives the negative acknowledgment including the same identification information within a predetermined time through the same relay apparatus and receives transmission data. The data transmission according to any one of claims 14 to 16, wherein a packet corresponding to the identification information is retransmitted to these receiving devices by a multicast method when received from the receiving devices. apparatus. An error resilience means for further dividing a transmitted packet into a plurality of sub-packets, grouping the plurality of sub-packets, adding redundant data, and rearranging the arrangement of the sub-packets. Item 16. The data transmission device according to item 15. It is applied to simultaneous transmission of program data of many channels,
The packet transmitting means transmits program data in each channel in a predetermined transmission order, and when there is a surplus band not used for transmitting the program data, increases the transmission speed of the program data being transmitted using the surplus band. 17. The data transmission device according to claim 14, wherein transmission of untransmitted program data is started.

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