WO2005029806A1

WO2005029806A1 - Method for transmitting data and data transmitter

Info

Publication number: WO2005029806A1
Application number: PCT/JP2004/002947
Authority: WO
Inventors: Makoto Takizawa; Takuya Tojo
Original assignee: Tokyo Denki University
Priority date: 2003-09-19
Filing date: 2004-03-08
Publication date: 2005-03-31
Also published as: JPWO2005029806A1; JP4382752B2

Abstract

A method for transmitting data and a data transmitter in which (a) distributed transmission of a specified number of segments, each consisting of a predetermined number of packet groups added with a parity packet as a first phase at each transmission rate, is performed, (b) distributed transmission of a specified number of segments, each consisting of a predetermined number of data packet groups not including a parity packet as a second phase, is performed if data loss does not occur, (c) data transmission of first phase and data transmission of second phase are repeated by increasing the data transmission rate by one stage if data loss does not occur even in the second phase, and (d) throughput of data communication is enhanced by performing an operation for returning to the immediately previous phase upon occurrence of data loss during any one data transmission interval and for retransmitting the data so that the data can be recovered on the receiving side thereby minimizing missing of data packets.

Description

Description Data transmission method and data transmission device

The present invention relates to a data transmission method and a data transmission device. Background art

As disclosed in Patent Literature 1 and Patent Literature 2, protocols conventionally used for transmitting data packets over an information network, for example, TCP (iranssion Control Protocol, XII, P (Xpress Transport Protocol) employs advanced window control technology and uses a communication algorithm called slow start to avoid network congestion.This slow start starts transmission at the base window size and receives data from the receiver. When a successful ACK arrives, the window size is increased at a fixed rate. If a received ACK does not arrive or a reception failure NACK arrives, (a) the transmission window size is returned to the base window size and finally Transmission resumes from the bucket following the bucket that received the ACK for successful reception, and the window size gradually increases in the same manner. Or (b) reduce the transmission window size to the window size at the time of receiving the ACK of the last successful reception, restart transmission from the bucket next to the bucket of the last ACK of the successful reception, A communication algorithm that gradually increases the window size in the same way.The communication algorithm that uses the conventional slow-start window control allows the network environment to accept all the data desired by the sender. Within a range that is relatively fast and reliable There is a feature that can be transmitted to the receiving side.

However, the amount of data transmitted using recent information networks has become enormous, but the processing speed of the data received by the software in the receiving PC (personal computer) has increased. If the high-speed communication speed of the receiver cannot follow, and the data processing speed of the receiving side becomes a bottleneck rather than on the network, a lot of data buckets will be lost, and a situation will occur. I'm familiar.

When a data bucket is transmitted using the conventional slow start communication algorithm in such a network communication environment, the data bucket is lost not because of the network but because of the processing speed of the software in the receiving device. The number of buckets increases and the frequency of packet retransmission increases.However, in the slow-start communication algorithm, the data lost on the receiving side causes the transmitting side to lose the data in the procedure (a) or (b) above. It takes a long round-trip time from the start of the packet to the restart of transmission. Therefore, even if the window control technology of the slow start method is adopted, there is a problem that the transmission time for transmitting a certain amount of data becomes longer as the frequency of packet loss increases.

As a technique for guaranteeing the reliability of data transmission, a technique using parity has been known. Patent Literature 3 adds a parity bucket having data that can be restored from the data of the remaining buckets even if one of them is lost for each of a fixed number of k−1 buckets, and the k packet data is reduced to 1 packet. As a segment, a technology for transmitting one segment at a time is disclosed. However, in this transmission method, two or more consecutive packets are often lost, so the data loss event in the receiving computer, the processing speed of the software on the computer side cannot keep up with the communication speed, Mass of data in computer However, there was a problem that it was not possible to cope with the event that the data was lost, data retransmission requests frequently occurred, and it was not possible to improve the actual communication speed.

Also, in packet transmission, Patent Document 4 discloses a communication speed control technology that increases the communication speed while congestion does not occur in a packet network and reduces the communication speed if there is a possibility of congestion. Although this communication speed control can be expected to substantially improve the communication speed, a predetermined number of packets is regarded as one segment, and if the transmission is successful, the communication speed is increased by one step. (One) and one parity bucket are transmitted as one segment, and if successful, a predetermined number of data buckets are transmitted as one segment without a parity bucket. No control is disclosed for increasing the number of data buckets at the same communication speed to substantially increase the communication speed.

As a technique for further improving the reliability of data transfer, Patent Document 5 utilizes a plurality of transmission paths. For example, (N-1) data packets and one parity packet are used to divide N buckets into one segment. A technique for transmitting buckets of M segments in a matrix manner over M transmission paths is disclosed. As a result, even if one bucket is lost on one of the transmission lines, the packet can be restored on the receiving side, eliminating the need for retransmission and enabling high reliability and high-speed communication. However, since multiple transmission lines are used, equipment costs are increased, and the process of restoring a series of data on the receiving side is complicated.

Patent Document 1 Japanese Patent Application Publication No.

Patent Document 2 Japanese Patent Application Laid-Open No. 2003-7785556

Patent Literature 3 Japanese Patent Application Laid-Open No. 2-2199336

Patent Document 4 Japanese Patent Application Laid-Open No. 7-66683 Patent Document 5: Japanese Patent Application Laid-Open No. 2002-36811 Disclosure of the Invention

The present invention has been made in view of the above-mentioned conventional technical problems, and enables data recovery on the receiving side to minimize loss of data packets as much as possible, thereby achieving comprehensive data communication. An object of the present invention is to provide a data transmission technology capable of improving speed throughput.

One feature of the present invention resides in a data transmission method. This data transmission method includes: (a) a fixed number N (N is an arbitrary natural number) to which a parity packet is added at a predetermined transmission rate at a predetermined transmission rate; The packet group of (1) is defined as one segment, and a segment of a constant M (M is an arbitrary natural number) is included in each transmitted packet group in which the packets belonging to each segment consist of a series of M packets. Performing a data transmission in a first transmission phase for distributing and transmitting a total of NXM buckets for N groups for each transmission packet group in a rare case; and (b) performing the first transmission phase in (a). If no data loss occurs during transmission, a data bucket group having the same transmission rate as that of the first transmission phase in (a) but not including parity packets and having the same total number of packets as the first transmission phase is transmitted. Pa And (c) increasing the transmission rate by one preset level if no data loss occurs even in the transmission of the second transmission phase of (b). Performing data transmission in the first transmission phase; and (d) performing data transmission in the second transmission phase if no data loss occurs in the data transmission in the first transmission phase in (c). ( _E ) transmitting the data in the first transmission phase of (c) while increasing the transmission rate by a predetermined step unless a data loss occurs after ( _e ); and transmitting the second transmission of (d) Phase Day (F) If data loss occurs during any data transmission period, return to the previous phase and restart data transmission.

Another feature of the present invention resides in a data transmission method. This data transmission method comprises the steps of: (a) adding a parity packet at a predetermined transmission rate to a fixed number N of bucket groups on a single transmission path; A predetermined number M of segments, and N packets for each transmission packet group, so that one packet is included in each of the transmission packet groups consisting of a series of M buckets belonging to each segment, for a total of NXM (B) performing data transmission in the first transmission phase for distributing and transmitting the bucket of (a), if no data loss occurs in the transmission of the first transmission phase of (a), A second transmission phase in which a data packet group having the same transmission rate as one transmission phase, including no parity packet, and having the same total number of buckets as the first transmission phase is transmitted in a burst manner. Transmitting data; and (c) increasing the transmission speed by one preset level if no data loss occurs even in the transmission of the second transmission fuse in the above (b). (D) performing data transmission in the second transmission phase if no data loss occurs in the data transmission in the first transmission phase in (c); and (e) Repeating the data transmission in the first transmission phase of the above (c) and the data transmission in the second transmission phase of the above (d) while keeping the transmission speed in a predetermined one-step increment unless data loss occurs. (F) If data loss occurs during any of the data transmission periods, if it is data transmission in the second transmission phase, return to the first transmission phase at the same transmission rate and restart data transmission. Steps and, (g) if data loss occurs in any of the data transmission period, place it is a data transmission of the first transmission phase In this case, the transmission speed is reduced by one predetermined stage, and the data transmission is restarted in the first transmission phase.

Still another feature of the present invention resides in a data transmission device, which includes a data holding unit that holds data to be transmitted, a network interface that sends and receives data to and from an information network through a single transmission path, A packetization processing unit configured to bucket data to be transmitted held in the data holding unit, a parity bucket generation unit configured to generate a parity packet for a fixed (N−1) packet sequence, The transmission phase determining unit that determines the current transmission phase and the transmission speed based on the information on the unsuccessful transmission and the information on the previous transmission phase, and information on the transmission phase determined by the transmission phase determining unit. Based on the above, the fixed number N of bucket groups to which the parity packet is A transmission packet group creation unit that generates or generates a data packet group that does not include the parity packet and has the same number as the total number of packets NXM in the predetermined number M of segments; and a transmission phase determination unit. A data transmission processing unit that transmits the packet group generated by the transmission packet group creation unit to the information network via the network interface at the determined transmission speed, wherein the transmission phase determination unit comprises: (a) At a given transmission rate, a fixed number N of packet groups to which a parity bucket is added is divided into one segment, and a given number M of segments are transmitted.A packet belonging to each segment consists of a series of M buckets. NXM buckets for each transmission bucket group are distributed and transmitted for N groups. (B) If no data loss occurs in the transmission of the first transmission phase of (a), the transmission rate is the same as the transmission rate of the first transmission phase of (a). Transmission rate, not including parity packets, and Data transmission in the second transmission phase, in which data bucket groups having the same total number of buckets as one transmission phase are transmitted in a burst manner, is performed. (C) Data loss also occurs in the transmission in the second transmission phase of (b) above. If not, the transmission rate is increased by a preset level to perform the data transmission in the first transmission phase, and (d) data loss occurs in the data transmission in the first transmission phase in (c). If not, the data transmission in the second transmission phase is performed. After (e), the data in the first transmission phase in the above (c) is increased while the transmission speed is increased by a predetermined step unless data loss occurs. The transmission and the data transmission of the second transmission phase (d) are repeated. (F) If data loss occurs during any of the data transmission periods, the data transmission is returned to the previous transmission phase one time before. To resume It is characterized in that the current transmission phase and transmission speed are determined based on the following rules.

Still another feature of the present invention resides in a data transmission device, which includes a data holding unit that holds data to be transmitted, a network interface that sends and receives data to and from an information network through a single transmission path. A packetization processing unit configured to bucket data to be transmitted held in the data holding unit, and a parity bucket generation unit configured to generate a parity packet for a fixed (N−1) packet sequence. A transmission phase determining unit that determines the current transmission phase and transmission speed based on the information on the success or failure of the previous data transmission and the information on the previous transmission phase; and the transmission determined by the transmission phase determining unit. Based on the phase information, a predetermined number M of segments, with a fixed number N of packet groups to which the parity packet is added as one segment Or a transmission packet group creation unit that does not include the parity packet and generates the same number of data bucket groups as the total number of packets NXM in the predetermined number M of segments, and the transmission packet At the transmission speed determined by the A data transmission processing unit for transmitting the packet group generated by the transmission bucket group creation unit to the information network via the network interface, wherein the transmission phase determination unit comprises: , A fixed number N (N is an arbitrary natural number) of packet groups to which a parity packet is added is defined as one segment, and a predetermined number M (M is an arbitrary natural number) of segments is formed. Data packets in the first transmission phase for distributed transmission of NXM buckets for N groups for each transmission packet group so that one packet is included in each transmission packet group consisting of (b) If no data loss occurs in the transmission of the first transmission phase of (a), the parity transmission is performed at the same transmission rate as that of the first transmission phase of (a). (C) performing data transmission in a second transmission phase for transmitting a data packet group having the same total number of packets as in the first transmission phase in a burst manner, including no packets, and (c) performing the second transmission in (b). If data loss does not occur even in the transmission of the transmission phase, the transmission rate is increased by one step set in advance, and the data transmission of the first transmission phase is performed. (D) The first transmission phase of (c) is performed. If no data loss occurs during the data transmission of the delay, the data transmission in the second transmission phase is performed. (E) Thereafter, as long as the data loss does not occur, the above (c) while increasing the transmission speed by a predetermined step at a time. ) Of the first transmission phase and the data transmission of the second transmission phase (d) are repeated. (F) If data loss occurs during any data transmission period, this is the second transmission phase. data from If it is a transmission, return to the first transmission phase at the same transmission rate and resume data transmission. (G) If data loss occurs during any of the data transmission periods, this is the data transmission in the first transmission phase. If this is the case, the transmission speed and the transmission speed are reduced based on the rule that the transmission speed is reduced by one predetermined level and data transmission is restarted in the first transmission phase. It is characterized in that it is determined. Brief Description of Drawings

FIG. 1 is a block diagram showing a functional configuration of a data transmission device according to one embodiment of the present invention.

FIG. 2 is a block diagram showing a functional configuration of a data receiving device corresponding to the data transmitting device of the embodiment.

FIG. 3 is an explanatory diagram of a bucketing process of application data in the embodiment.

FIG. 4 is an explanatory diagram of a distributed transmission process of a plurality of segments according to the above embodiment. FIG. 5 is a flowchart of a data transmission process by the data transmission device of the above embodiment.

FIG. 6 is a sequence diagram of the first and first transmission phase data transmission processing by the data transmission device of the above embodiment.

FIG. 7 is a sequence diagram of the first and second transmission phase data transmission processing by the data transmission device of the above embodiment.

FIG. 8 is a sequence diagram of a second first transmission phase data transmission process in which the data transmission device according to the above embodiment has increased the speed by one step.

FIG. 9 is a sequence diagram of a second transmission phase data transmission process performed by the data transmission device of the above-described embodiment at a one-step speed reduction due to a data loss occurring in the second first transmission phase.

10A is an explanatory diagram of the first transmission phase data transmission according to the embodiment, and FIG. 10B is an explanatory diagram of the second transmission phase data transmission.

FIG. 11 shows data transmission by the data transmission device according to the second embodiment of the present invention. Flowchart of communication processing.

FIG. 12 is an explanatory diagram showing a data bucket string transmitted by the data transmission method according to the third embodiment of the present invention.

FIG. 13 is an explanatory diagram of a data bucket string and a parity bucket string transmitted by the data transmission method according to the third embodiment.

FIG. 14 is an explanatory diagram showing a first stage of data transmission according to the third embodiment.

FIG. 15 is an explanatory diagram showing a second stage of data transmission according to the third embodiment.

FIG. 16 is an explanatory diagram showing a third stage of data transmission according to the third embodiment.

FIG. 17 is an explanatory diagram showing a fourth stage of data transmission according to the third embodiment.

FIG. 18 is an explanatory diagram showing a fifth stage of the data transmission according to the third embodiment.

FIG. 19 is an explanatory diagram showing a sixth stage of data transmission according to the third embodiment.

FIG. 20 is an explanatory diagram showing a seventh stage of data transmission according to the third embodiment.

FIG. 21 is an explanatory diagram showing an eighth stage of data transmission according to the third embodiment.

FIG. 22 is a sequence diagram of data transmission in the first transmission phase at a speed of the base 5 O M bps in the data transmission method according to the first embodiment of the present invention.

FIG. 23 is a sequence diagram of data transmission in the first transmission phase at a speed of 60 Mbps in the data transmission method of the first embodiment. FIG. 24 is a sequence diagram of data transmission in the first transmission phase at a speed of 70 Mbps in the data transmission method according to the first embodiment.

FIG. 25 is a graph of data transmission characteristics according to the first embodiment.

Figure 26 is a graph of data transmission characteristics according to Comparative Example 1.

FIG. 27 is a graph of a measurement result of a packet reception speed by the data transmission method according to the second embodiment of the present invention.

FIG. 28 is a graph of the measurement result of the bucket loss rate according to the second embodiment. Fig. 29 is a graph of the results of measuring the bucket receiving speed by the data transmission method of Comparative Example 2.

FIG. 30 is a graph of a measurement result of a packet loss rate according to Comparative Example 2. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a functional configuration of a data transmitting apparatus 10 according to a first embodiment of the present invention, and FIG. 2 shows a functional configuration of a data receiving apparatus 20 that receives transmission data of the data transmitting apparatus 10. ing.

The data transmitting device 10 and the data receiving device 20 are both incorporated as software in a computer having a data packet communication function, and usually have both transmitting and receiving functions simultaneously. For convenience, it is shown separately for the transmitting side and the receiving side.

The functional configuration of the data transmission device 10 includes an HDD that stores large amounts of data, a data storage unit 11 that includes a RAM memory that temporarily stores data, and data to be transmitted from this data storage unit 11. A bucketing processing unit 12 that takes out and performs a bucketing process, a parity adding process that generates a parity packet as necessary for a series of packet sequences of the bucketed data. Part 13.Determine the transmission rate and the transmission phase of the first transmission phase (first phase) or the second transmission phase (second phase) based on a predetermined rule according to the data transmission situation The transmission phase deciding unit 14, the transmission speed indicated by the transmission phase deciding unit 14, the data transmission processing unit 15 for transmitting the data bucketed in the transmission phase, the data reception processing unit 16 for receiving external data, For example, a hardware network interface (NW I / F) 17 including a LAN board, a LAN adapter, and a router and serving as an interface with the network 30 is provided.

On the other hand, the functional configuration of the data receiving device 20 includes a data receiving processing unit 21 for receiving data transmitted from the data transmitting device 10 through the network 30 and a memory 2 for temporarily storing received data. 2.Parity check unit 23 that performs parity check on received data 23.Data recovery processing unit 24 that attempts to recover data using a parity bucket added to the received data sequence when a data error occurs. The communication status determination unit 25, which determines the success or failure of the data reception based on the status of the memory 22 and the success or failure of the data recovery of the data recovery processing unit 24, and the result of the data reception success / failure determination by the communication status determination unit 25, which is based on A data transmission processing unit 26 for transmitting ACK and NAK signals, and also includes, for example, a LAN board, a LAN adapter and a router as well as the transmission side, and an interface with the network 30. It is equipped with a hardware of Netw network interface (NW I / F) 2 7 which acts as a face.

The network 30 is a LAN, a public communication network, the Internet, or an information network that uses these in an integrated manner, and is capable of transmitting data packets.

Next, a data communication process between the data transmitting device 10 and the data receiving device 20 having the above configuration will be described. First, the data bucket communication used in the present embodiment will be described. As shown in Fig. 3, the application data is divided into fixed-length packets pk1, k2, ..., and the exclusive-OR (XOR) of all packets for a fixed number m of packets pk1 to pkm is calculated. Calculation is performed, and the calculation result is used as a parity packet. The predetermined number of data packets and one parity bucket constitute one segment SG.

In data transmission in the first transmission phase (first phase), a predetermined number of N-segment packets are transmitted in a distributed manner. Fig. 4 shows an example of transmitting a 2-segment SG1, SG2 packet group, which forms one segment with three buckets + one parity packet. In this case, the first packet (1) of segment SG1, the first packet (4) of segment SG2, the second packet (2) of segment SG1, and the second packet of segment SG2 (5),... Are transmitted in order, and finally the parity packets PT 1 and PT 2 of each segment are transmitted.

In this manner, a parity packet is generated for each bucket group consisting of a fixed number m of data buckets, and the bucket group consisting of m + 1 packets including the parity bucket is transmitted as one segment, thereby transmitting the packet. Even if one of the bucket groups is lost, the receiving side can correctly recover the remaining bucket groups and the lost packet data from the knowledge packet that were normally received.

Normally, bucket loss often occurs in bursts in data communication.However, if N (= m + 1) packets forming one segment are distributed and transmitted by M segments, then multiple segments are lost. There is a high possibility that buckets belonging to the packet group will be transmitted within that bursty period, and the receiving side can recover data using the parity packet described above for each segment, and The number of packets that can be recovered is increased, so that there is an advantage that packet loss can be reduced and reliable data transmission is possible.

The data transmission device 10 and the data reception device 20 perform data transmission by the method shown in the flowchart of FIG. 5 by using the generation / addition of the parity bucket and the distributed packet transmission.

In the data transmission device 10, if application data to be transmitted is generated, the data is divided into packets of a fixed length, in the following description, every 30,000 bytes, and parity is calculated for every 10 data packets in the first transmission stage. Then, a parity packet is generated, and a packetization process for forming one segment with 11 packets of 10 data packets + 1 parity packet is performed (steps S1, S3).

In the transmission start stage, it is assumed that the previous reception was successful (YE S in step S5), and that no parity packet was added in the previous transmission (0 in step 37), and the first transmission phase (first phase) is transmitted. As a preparation, one parity bucket is added to 10 data packets to make 11 segments into 1 packet, and 20 segments are prepared as shown in FIG. 6 (step S9A).

Subsequently, in the first transmission SK11, the base speed is set to 55 Mb s, which is 1.1 times the base speed of 50 Mb ps (step S11), and distributed transmission of 20 segments is started in the first transmission phase (step S11). S1 3).

It is assumed that the first transmission has been successfully transmitted without data loss. Here, the receiving side transmits a transmission speed gap to the transmitting side together with ACK due to the successful reception. It should be noted that if the transmitting side receives the ACK, it may decide to increase the speed by itself. <Second transmission process>

On the transmitting side, if it is determined that the reception was successful, the second transmission process is started. Since the reception was successful for the first transmission, the process branches to YES in step S5. In step S7, the parity bucket is initially transmitted. Since the packet is transmitted in the first transmission phase with the data added, the process branches to YES and prepares for transmission in the second transmission phase (second phase) (step S9B). In other words, as shown in Fig. 7, in the second transmission, without adding a parity packet, all packets in one segment are transmitted as data packets at the same transmission speed as the previous one, thus substantially increasing the speed. . Then, a data packet for 20 segments is transmitted in a burst manner (step S13; SK21). Suppose that the second transmission was successful without any data loss.

As a result, the base transmission rate was 50 Mbps for the data packet at the first real transmission rate shown in Fig. 6, but the second transmission was possible without the parity bucket. This means that the data could be transmitted at a transmission speed of 55 Mb ps, which is twice as high.

3rd transmission process>

In the third transmission process, as shown in Fig. 8, the speed is increased to 60.5 Mb ps, which is 1.1 times the initial transmission speed of 55 Mb ps, and the parity bucket is processed as in the first transmission. 1 bucket with 1 segment added is transmitted in a distributed manner in the first transmission phase for 20 segments (SK 21).

If no data loss occurs in the data transmission in the first transmission phase with this speed-up, the transmission speed is maintained at 60.5 Mb ps in the subsequent second transmission phase, as in the second transmission process. While adding a parity packet, a 1-segment 1-data packet is transmitted and a 20-segment data packet is transmitted in a burst manner. This allows real data transmission The transmission speed can be increased to 60.5 Mbps.

In the same manner, the packet group consisting of 10 data packets + 1 parity packet and 1 packet constitutes 1 segment in the 1st transmission phase while increasing the transmission rate by one step unless data loss occurs. Is transmitted in a predetermined segment, and if the transmission in the first transmission phase succeeds, in the subsequent second transmission phase, the data is composed of 1 segment and 1 data bucket and transmitted at the same transmission rate in a burst manner. Repeat the operation to increase the data transmission speed. The speed-up rate can be set, for example, by 1 OM bps or by 10%, but is not particularly limited.

As shown in FIG. 8, it is assumed here that a bucket loss has occurred in the third data transmission.

<4th transmission process>

In the third transmission, the first transmission phase (that is, the transmission phase in which a packet group consisting of 10 data buckets + 1 parity packet and 1 packet consisting of 1 segment is distributed for 20 segments) is transmitted in the first phase. If data loss occurs, one step before, in this case, as shown in Fig. 9, the procedure returns to the same procedure as the second transmission procedure and data transmission is restarted in the second transmission phase (SK twenty two ) . In other words, in the flowchart of FIG. 5, the process branches to NO in step S5, branches to YES in step S15 because the parity was transmitted last time, and performs the parity adding process in preparation for the transmission in the second transmission phase. (Step S17A), the communication speed is reduced by one step, and the data transmission in the second transmission phase is restarted (steps S19, S13). If data loss still occurs by the transmission operation shown in FIG. 9, if the data transmission is performed one more time before, that is, the first transmission is performed at the same transmission speed as the first transmission. The transmission in the transmission phase will be performed.

If the previous transmission phase was the second transmission phase and reception failed in the second transmission phase, the process branches to NO in step S5 in FIG. 5, and also branches to NO in step S15. Then, the first transmission phase is prepared (step S17B), and data is transmitted in the first transmission phase with the parity bucket added at the same transmission speed as the previous time (step S13).

Thus, in the data communication method of the present embodiment, (a) As shown in FIG. 10 (A), a fixed number of packets each having a parity bucket added as a first transmission phase (first phase) at each transmission rate. The bucket group is divided into one segment and distributed transmission of a predetermined number of segments is performed. (B) As shown in Fig. 10 (B), if no data loss occurs, the second transmission phase (second phase) is performed. A data packet group that does not include a parity packet and is the same as the total number of packets in the first transmission phase is transmitted in bursts. (C) If no data loss occurs in the second transmission phase, the transmission speed The data transmission in the first transmission phase shown in Fig. 10 (A) and the data transmission in the second transmission phase shown in Fig. 10 (B) are repeated, and (d) one of the data transmissions If data loss occurs during the period Resume sending data back to the transmission phase of the previous one, perform the operation that. In the data transmission of (d), for example, if data loss occurs in the second transmission phase of FIG. 10 (B), the transmission speed is maintained and the first transmission phase of FIG. 10 (A) is maintained. Then, if data loss occurs in the first transmission phase of Fig. 10 (A), the transmission speed is reduced by one step and transmission is restarted in the second transmission phase of Fig. 10 (B).

Also, in the above embodiment, for example, it is assumed that multimedia content is transmitted in a stream, and even if data loss occurs, the corresponding data group is retransmitted. Instead, the data transmission is restarted from a new data group one after another. However, if data loss occurs, the data transmission of the lost data group may be restarted.

As a result, according to the first embodiment, the redundancy is increased by the addition of the parity data, and the data loss on the network can be recovered by the receiving side using the parity data from the received data, and complete data loss can be achieved. Therefore, if there is no data loss in the first transmission phase, the parity packet is not included in the second transmission phase, and the retransmission is not performed in the first transmission phase. In addition, by transmitting the same number of data packets as the total number of buckets in the first transmission phase in a burst manner at the same transmission speed, the parity packet was transmitted at the transmission speed that is likely to succeed this time because it was successful last time. The number of data packets transmitted at the same transmission rate can be increased by replacing Only the actual transmission speed can be increased, and as a result of all these, the throughput of data transmission can be improved.

Next, a data transmission device and a data transmission method according to a second embodiment of the present invention will be described using FIG. 1, FIG. 2, and FIG. The second embodiment differs from the first embodiment in the method of reducing the communication speed when the transmission fails in the first transmission phase. If the transmission fails in the first transmission phase, the transmission speed is reduced by one step. Data transmission is resumed in the same first transmission phase after the floor has been lowered. Therefore, the functional configuration of the data transmission device is the same as that shown in FIGS. 1 and 2 as in the first embodiment. However, in the case of the present embodiment, if there is a transmission failure in the previous second transmission phase, the transmission phase determination unit 15 determines to transmit in the first transmission phase at the same transmission speed. If there is a transmission failure in one transmission phase, the transmission speed is reduced by one step and the same Decide to resume data transmission in the transmission phase.

FIG. 11 is a flowchart of a data transmission process performed by the data transmission device according to the present embodiment. In the data transmission process according to the second embodiment, the process of substantially increasing the speed when the previous data transmission succeeds is the same as that of the first embodiment. Also, the processing when the previous data transmission failed and the previous transmission phase was the second transmission phase is the same as in the first embodiment. The procedure branches to NO, and also branches to NO in step S15, prepares for the first transmission phase (step S17B), and adds the parity bucket at the same transmission rate as the previous transmission phase. (Step S13).

As a feature of the present embodiment, when the previous data transmission has failed and the previous transmission phase was the first transmission phase, the process branches to YES in step S15, and is the same as the previous time. It prepares for data transmission in the first transmission phase (step S17C), and performs processing to reduce the transmission speed by one step from the previous time and restart data transmission (steps S19, S13).

According to the second embodiment, as in the first embodiment, redundancy is increased by adding parity data, and data loss on the network can be recovered by the receiving side using parity data from the received data. As a result, the chances of complete data loss can be reduced, the chances of retransmission for data loss can be reduced accordingly, and if no data loss occurs in the first transmission phase, the parity packet is transmitted as the second transmission phase. By transmitting the same number of data bucket groups as the total number of buckets in the first transmission phase, in bursts at the same transmission speed, the transmission was successful the previous time, so this transmission is likely to succeed this time The number of data packets transmitted at the same transmission rate can be increased by replacing parity packets with data packets at the same transmission speed. To Therefore, the transmission rate can be substantially increased, and the overall result can improve the throughput of data transmission.

Next, a third embodiment of the present invention will be described with reference to FIGS. The system configuration of the data transmission device of the third embodiment is the same as that of the first embodiment and the second embodiment, but has a feature in its redundant data transmission method. The transmission method shown in 1 is taken. Now, as shown in FIGS. 12 and 13, the data packets to be transmitted are data packets (1) to (6), and data packets (1), (3) and (5) are segments. It is assumed that the packet group belonging to SG1 and the data packets (2), (4), (6) are the packet group belonging to segment SG2. In addition, when a parity packet PT1 and a parity packet PT2 are added to each of the segments SG1 and SG2 for redundancy to be transmitted, the redundant packet transmission is performed as follows. .

As shown in Fig. 14, the data packets (1), (3), and (5) belonging to each of the segments SG1 and SG2 and the data packets (2), (4), The transmission starts with the packet group of (6) arranged in a line in the transmission order. Then, the packet (1) belonging to the segment SG1 to be transmitted first is transmitted, and at this time, the parity is recorded in the parity packet PT1 for the segment SG1.

Next, as shown in FIG. 15, the first data packet (2) belonging to the segment SG2 is transmitted, and at this time, the parity is recorded in the parity packet PT2 for the segment SG2.

Subsequently, as shown in FIG. 16, the second data packet (3) belonging to the reproduction segment SG1 is transmitted, and at this time, the parity is recorded in the parity packet PT1 for the segment SG1. . Following this, Figure 17 shows As described above, the second data packet (4) belonging to the segment SG2 is transmitted, and the parity is recorded in the parity bucket PT2 for the segment SG2.

Hereinafter, the same transmission procedure is repeated. Then, as shown in FIG. 18, the last data packet (5) of the segment SG 1 is transmitted, its parity is recorded in the parity packet PT1, and then, as shown in FIG. The data packet (6) is transmitted and its parity is recorded in the parity bucket PT2. Finally, as shown in FIGS. 20 and 21, a parity packet PT1 for the segment SG1 and a parity packet PT2 for the segment SG2 are transmitted.

In this way, data buckets belonging to each of a plurality of segments to be transmitted at the same time are sequentially transmitted, and at the time of transmission of each data bucket, the parity is recorded in the parity packet for each segment. Finally, by transmitting a parity packet group of each of a plurality of segments, it is not necessary to generate a parity packet for each segment in advance, and the efficiency of redundant data transmission can be improved. Example 1

The results of evaluating the data transmission by the two-phase slow-start transmission method of the present invention and the data transmission by the conventional slow-start congestion avoidance control transmission method according to the present invention shown in Figs. 22 to 24 are shown in the graphs of Figs. 25 and 26. Indicated. The data transmission amount is the same.In the embodiment of the present invention, the speed is increased by 10 Mbps when data transmission is successful, the speed is decreased by 10 Mbps when data loss occurs, and the control is performed in the second transmission phase. Is omitted.

That is, first, as shown in Fig. 22, the first phase, parity at 50 Mbps 1 segment 2 including 1 packet is transmitted for 20 segments (SK2111). This base transmission rate is 4.8 msec / packet.

If the transmission of this SK211 succeeds, the speed is increased by 10 Mbps, and as shown in Fig. 23, 1 segment 21 packets including the parity packet at 60 Mbps in the first phase are transmitted for 20 segments. Yes (SK2 2 1). The transmission speed at this time is 4.0 msec / packet.

Then, if the transmission of SK2221 succeeds, the speed is further increased by 10 Mbps, and as shown in Fig. 24, the first phase, 70 Mbps, and 1 segment 21 packets including the knowledge packet are 20 segments. Minute (SK 2 3 1). The transmission speed at this time is 3.4 msec / packet.

If a packet loss occurs in the transmission of SK231, in the next transmission, the speed is reduced by 1 OMbs, and the transmission is performed in the first phase at a speed of 60 Mbps.

The transmission characteristics and transmission results of the data transmission method of Example 1 and the conventional data transmission method (Comparative Example 1) were measured. According to this, as shown in the graph of Example 1 in FIG. 25 and the graph of Comparative Example 1 in FIG. 26, in the one-to-one evaluation using Gigabit Ethernet (registered trademark), It was demonstrated that the data transmission according to the first embodiment can communicate with a loss rate of 43.9% less than the slow start of the first embodiment. In the case of the present invention, the packet recovery rate was 41.2%.

Example 2

The data transmission by the two-phase slow start transmission method according to the third embodiment of the present invention and the data transmission by the conventional slow start transmission method were evaluated. As an experimental environment, two computers, PC1 and PC2, were connected by Gigabit Ethernet (registered trademark), and PC1 and PC2 were operated with NIST Net (trade name) software of a delay generation emulator. The delay time required for data transmission from PC 1 to PC 2 was set to 100 msec. This results in a round-trip delay of 200 ms, which is equivalent to the delay of a long-distance network between Japan and the United States. This NIST Net is "The Linux-based Network Emulation Tool NIST Net" and was obtained from http://snad.ncsl.nist.gov/itg/nistnet/.

Under this condition, data was transmitted from PC2 to PC1, and the difference between the transmission speed and the bucket loss rate due to the two algorithms of the conventional slow start and the two-phase slow start (TPSS) according to the present invention was evaluated.

To change the transmission speed, if the packet loss rate exceeds 5%, the receiver requests the transmitter to increase the transmission speed by 0.8, otherwise it increases the speed by 1.2 times. Decided to request.

And in T P S S,

(1) If the packet loss rate does not exceed 5% in the transmission of the first transmission phase, transmit without redundancy in the second transmission phase, and transmit if the loss rate does not exceed 5% in the second transmission phase. Redundant so that the speed becomes 1.2 times, and start the first transmission phase.

(2) If the loss rate exceeds 5% in the first transmission phase and the second transmission phase, return to the previous second transmission phase,

Was set to the condition.

The experimental conditions in this Example 2 were as shown in Table 1 below.

Table 1 Transmission conditions of this embodiment Transmission method TPSS

Number of segments for distributed transmission 20 segments

Number of data packets per segment 5 packets

Transmission time 1 50sec

One-way delay time 100 ms On the other hand, the experimental conditions of Comparative Example 2 were as shown in Table 2 below.

Table 2 Transmission conditions for Comparative Example 2

The evaluation results of the transmission test performed under these transmission conditions are shown in Tables 3 and 4 below and shown in Figs. 27 to 30.

Table 3 Evaluation results of Example 2

Number of received packets 267 257 packets

Number of lost packets 1 5181 packets

(Loss rate) (5.37%) Table 4. Evaluation results of Comparative Example 2

Number of received packets 275646 packets

Number of lost packets 77292 packets

(Loss rate) (21.88%) From this experimental result, it was confirmed that the data transmission according to the second embodiment can improve the effective transmission speed. Industrial potential

According to the present invention, the redundancy is increased by the addition of parity data, and the data loss on the network can be recovered by the receiving side using the parity data from the received data, so that the opportunity for complete data loss can be reduced. The chances of retransmission for data loss can be reduced, and if no data loss occurs in the first transmission phase, the parity packet is not included in the second transmission phase, and the total buckets in the first transmission phase By transmitting the same number of data buckets in bursts at the same transmission rate, the parity packet is replaced with data packets at the transmission rate that is likely to succeed this time because it succeeded the previous time. As a result, the number of data packets transmitted at the same transmission speed can be increased, and the actual transmission speed is increased accordingly. Can and this, as these overall results, the throughput of data transmission can be improved.

Claims

Scope of Claim 1. On a single transmission line,

(a) At a given transmission rate, a fixed number N (N is an arbitrary natural number) packet group to which a parity packet is added is divided into one segment, and a predetermined number M (M is an arbitrary natural number) of segments is added to each segment. A first transmission phase in which packets belonging to N groups, a total of NXM packets, are distributed and transmitted for each of the transmission bucket groups so that one packet belongs to each transmission bucket group consisting of a series of M buckets. Transmitting the data of

(b) If no data loss occurs in the transmission of the first transmission phase of (a), the transmission rate is the same as the transmission rate of the first transmission phase of (a), and no parity bucket is included; and Performing data transmission in a second transmission phase for transmitting a data packet group having the same total number of buckets as the first transmission phase in a burst manner;

(c) performing a data transmission in the first transmission phase by increasing the transmission speed by one preset stage if no data loss occurs even in the transmission in the second transmission phase in (b);

(d) performing a data transmission in the second transmission phase if no data loss occurs in the data transmission in the first transmission phase in (c); and Repeating the data transmission in the first transmission phase of (c) and the data transmission of the second transmission phase in (d) while increasing the

(f) If data loss occurs during any of the data transmission periods, returning to the previous phase and restarting data transmission.

2. On a single transmission line,

(a) At a given transmission rate, a fixed number N (N is an arbitrary natural number) packet group to which a parity packet is added is divided into one segment, and a predetermined number M (M is an arbitrary natural number) of segments is added to each segment. The first transmission phase in which packets belonging to N groups are distributed for each of the transmission bucket groups so that one packet belongs to each transmission bucket group consisting of a series of M packets, and a total of NXM buckets are transmitted. Transmitting the data of

(b) If no data loss occurs in the transmission of the first transmission phase of (a), the transmission rate is the same as the transmission rate of the first transmission phase of (a), and no parity packet is included, and Performing a data transmission in a second transmission phase for transmitting a data bucket group having the same total number of buckets as the first transmission phase in a burst manner;

(d) performing data transmission in the second transmission phase if no data loss occurs in the data transmission in the first transmission phase in (c);

(e) Thereafter, as long as no data loss occurs, the data transmission in the first transmission phase of (c) while increasing the transmission speed by a predetermined step, and the data of the second transmission phase in (d) above Repeating the transmission;

(f) If data loss occurs during any of the data transmission periods, if it is data transmission in the second transmission phase, return to the first transmission phase at the same transmission speed and restart data transmission When,

(g) If data loss occurs during any of the data transmission periods, and if it is data transmission in the first transmission phase, the transmission speed is increased by one predetermined stage. And d. Resuming data transmission in the first transmission phase.

3. A data holding unit for holding data to be transmitted,

A network interface for exchanging data with the information network through a single transmission line,

A packetization processing unit that packetizes data to be transmitted held in the data holding unit;

A parity packet generator for generating a parity packet for a fixed (N-1) packet sequence;

A transmission phase determining unit that determines the current transmission phase and the transmission speed based on the information on the success or failure of the previous data transmission and the information on the previous transmission phase;

Based on the information on the transmission phase determined by the transmission phase determining unit, a predetermined number M of segments is generated by dividing the fixed number N of bucket groups to which the parity bucket is added into one segment, or including the parity packet. And a transmission bucket group creation unit for generating a data bucket group of the same number as the total number of buckets NXM in the predetermined number M of segments,

A data transmission processing unit that transmits the packet group generated by the transmission packet group generation unit to the information network via the network interface at the transmission speed determined by the transmission phase determination unit;

The transmission phase determination unit,

(a) At a given transmission rate, a packet group of a fixed number N (N is an arbitrary natural number) to which a parity packet is added is made into one segment, and a segment of a predetermined number M (M is an arbitrary natural number) is divided into A packet belonging to a segment is included in each of a series of M packets of transmission packets. In this way, data transmission in the first transmission phase for distributing and transmitting NXM buckets for N groups for each transmission packet group is performed.

(b) if no data loss occurs in the transmission of the first transmission phase of (a), the transmission rate is the same as the transmission rate of the first transmission phase of (a), no parity packet is included, and Perform data transmission in the second transmission phase for transmitting data packets of the same total number of packets as in the first transmission phase in a burst manner,

(c) If data loss does not occur even in the transmission of the second transmission phase of (b), the transmission rate is increased by one preset level, and the data transmission of the first transmission phase is performed.

(d) if no data loss occurs in the data transmission in the first transmission phase of (c), perform the data transmission in the second transmission phase;

(e) Thereafter, the data transmission in the first transmission phase of (c) and the data transmission of the second transmission phase in (d) while increasing the transmission speed by a predetermined step at a time unless data loss occurs, Repeatedly,

(f) If data loss occurs during any data transmission period, return to the previous transmission phase and restart data transmission;

A data transmission device that determines the current transmission phase and transmission speed based on the following rule.

4. A data holding unit for holding data to be transmitted,

A packetization processing unit configured to bucket data to be transmitted held in the data holding unit;

—Generate parity packets for a fixed number (N-1) of packet sequences A parity bucket generator,

A transmission phase determining unit that determines the current transmission phase and transmission speed based on the information on the success / failure of the previous data transmission and the information on the previous transmission phase;

Based on the information on the transmission phase determined by the transmission phase determination unit, a predetermined number M of segments is generated by dividing the fixed number N of packet groups to which the parity packet is added into one segment, or the parity packet is generated. First, a transmission packet group creation unit that generates a data packet group of the same number as the total number of buckets NXM in the predetermined number M of segments,

The transmission phase determining unit,

(a) At a given transmission rate, a packet group of a fixed number N (N is an arbitrary natural number) to which a parity packet is added is made into one segment, and a segment of a predetermined number M (M is an arbitrary natural number) is divided into A total of NXM buckets are distributed and transmitted so that one packet belonging to the segment is included in each of the M transmission packets, and one N packet for each transmission packet group. Performs data transmission of the first transmission phase,

(b) if no data loss occurs in the transmission of the first transmission phase of (a), the transmission rate is the same as the transmission rate of the first transmission phase of (a), and no parity packet is included; and Performing data transmission in a second transmission phase for transmitting a data packet group having the same total number of packets as the first transmission phase in a burst manner,

(c) Even in the transmission of the second transmission phase of (b), data loss occurs. If it does not occur, increase the transmission speed by one preset level, perform data transmission in the first transmission phase,

(f) If data loss occurs during any of the data transmission periods, if it is data transmission in the second transmission phase, return to the first transmission phase at the same transmission rate and resume data transmission,

(g) If data loss occurs during any of the data transmission periods, if it is data transmission in the first transmission phase, the transmission speed is reduced by one predetermined level, and data is lost in the first transmission phase. A data transmission device characterized in that the current transmission phase and transmission speed are determined based on a rule that transmission is restarted.