JP2013098759A - Data transmission device and data reception device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a data transmission device capable of estimating a band of cross traffic, and controlling a transmission rate according to the band.SOLUTION: A data transmission device 1 includes: transmission rate measuring means 10 for measuring a transmission rate, and using that as a temporary transmission rate of a packet which is newly transmitted; packet transmitting means 11 for transmission the packet to a data reception deice 2 when the temporary transmission rate is the maximum transmission rate or less; receiving information obtaining means 12 for obtaining a reception rate when the receiving the packet, as receiving information, from the data reception device 2, in associated with an identifier included in the packet; and maximum transmission rate calculating means 13a for calculating and updating the maximum transmission rate, on the basis of a temporary transmission rate corresponding to the packet transmitted by the packet transmitting means 11 and the reception rate corresponding to the identifier of the packet.

Description

  The present invention relates to a data transmission device and a data reception device that transmit and receive data by packet communication.

In recent years, video distribution services using packet communication such as VoD (Video on Demand) and live streaming have been provided.
When this video distribution service is performed on a best-effort type IP network where quality is not guaranteed, if the available bandwidth of the network falls below the transmission rate of the data to be temporarily transmitted, these data are transferred on the transmission path. Since the data is transmitted after being buffered in the communication device, the delay temporarily increases greatly.
In addition, when reproducing a moving image, the reproduction is stopped unless data is continuously received. Therefore, it is necessary to suppress such a large delay variation.

Accordingly, various techniques have been developed as techniques for preventing a large data delay from occurring on a network in which the available bandwidth varies.
For example, TCP Reno, which is one of the types of TCP (Transmission Control Protocol), considers occurrence of packet loss as a congestion signal and avoids congestion by reducing the transmission rate by half (see Non-Patent Document 1). ).

  Also, for example, RAP (Rate Adaptive Protocol), like TCP Reno, avoids congestion by detecting congestion signals and reducing the transmission rate by half, but it also measures changes in RTT (Round Trip Time). The accuracy of rate control is improved by applying feedback to the transmission rate (see Non-Patent Document 2).

  Another method is VTP (Video Transport Protocol) (see Non-Patent Document 3). This VTP is a protocol aimed at video transmission and sharing TCP and bandwidth fairly. When TCP detects congestion, the transmission rate is suddenly reduced. On the other hand, VTP reduces the amount of transmission rate reduction compared to TCP, and lengthens the data transmission time at the reduced rate. Thus, the transmission amount is finally the same as that of TCP. At this time, VTP uses a fixed value set in advance and a value calculated based on the measured reception rate as the amount of decrease in the transmission rate.

As another disclosed method, there is a method for controlling a transmission rate depending on whether or not a cross traffic (traffic by another communication terminal) exists (see Patent Document 1).
In this method, the existence of cross traffic is estimated by RTT. If there is no cross traffic, the bottleneck link bandwidth is set as the transmission rate. If cross traffic exists, it is set in advance according to the data to be transmitted. The lower limit transmission rate is used as the transmission rate.

JP 2005-198111 A

RFC2581-TCP Congestion Control "RAP: An End-to-end Rate-based Congestion Control Mechanism for Realtime Streams in the Internet" Reza Rejaie, Mark Handley, Deborah Estrin (18th Annual Joint Conference of the IEEE Computer and Communications Societies, Mar. 1999) "Adaptive Video Streaming in Presence of Wireless Errors," Guang Yang, Mario Gerla and M.Y.Sanadidi (The 7th IFIP / IEEE International Conference on Management of Multimedia Networks and Services, Oct. 2004)

  TCP and RAP described above halve the transmission rate when congestion is detected, but these do not consider the cross traffic that causes congestion, so if large cross traffic flows in, the amount of decrease in the transmission rate is not sufficient. Therefore, there is a problem that a large transmission delay occurs.

  In the VTP described above, since the amount of decrease in the transmission rate at the time of congestion is a value calculated based on a fixed value set in advance without considering cross traffic and the measured reception rate, TCP and RAP Similarly, there is a problem in that a large transmission delay occurs due to a large inflow of cross traffic.

  Further, although the method described in Patent Document 1 considers cross traffic, it simply changes the transmission rate according to the presence or absence of cross traffic, so that a large transmission delay is caused by the inflow of large cross traffic. The problem of occurring remains a problem.

  As described above, in the conventional method, there is a problem that an increase in transmission delay due to cross traffic causes quality degradation such as video and audio disturbance and freeze due to buffer underflow on the receiving side.

  The present invention has been made in view of the above problems, and provides a data transmission device and a data reception device capable of estimating a cross traffic band and controlling a transmission rate according to the band. The task is to do.

  The present invention has been made to solve the above-mentioned problems. First, the data transmission device according to claim 1 sends a packet including a packet identifier to the data reception device via the packet communication network. A data transmission apparatus for transmission includes a transmission rate measurement unit, a packet transmission unit, a reception information acquisition unit, and a maximum transmission rate calculation unit.

In such a configuration, the data transmission device measures the transmission rate of the packets to be transmitted sequentially by the transmission rate measuring means. This transmission rate can be regarded as a provisional transmission rate for the next packet transmission.
In addition, when the temporary transmission rate is equal to or lower than the maximum transmission rate, the data transmission device determines that the packet can be transmitted and transmits the next packet to be transmitted to the data reception device. As a result, the data transmission device transmits the packet within the range of the maximum transmission rate.

  In addition, the data transmission apparatus acquires, as reception information, a reception rate when the packet is received, from the data reception apparatus, in association with the packet identifier included in the packet, by the reception information acquisition unit. As a result, the data transmission apparatus can recognize at what reception rate the packet is received by the data reception apparatus.

Then, the data transmission device calculates and updates the maximum transmission rate by the maximum transmission rate calculation means based on the temporary transmission rate and the reception rate corresponding to the packet identifier.
That is, when the temporary transmission rate exceeds the reception rate, the maximum transmission rate calculation means obtains a value obtained by subtracting the cross-traffic bandwidth from the bottleneck link bandwidth that is known in advance or obtained by measurement. Calculate as The use band of the cross traffic can be obtained as the amount of traffic added to the bottleneck link band from the ratio between the temporary transmission rate and the reception rate.
Further, the maximum transmission rate calculation means adds a predetermined rate increase amount to the maximum transmission rate when the provisional transmission rate is equal to or lower than the reception rate to obtain a new maximum transmission rate.

  Further, the data transmission device according to claim 2 is the data transmission device according to claim 1, further comprising a delay limit determination means.

In such a configuration, the data transmission apparatus determines the tendency of the transmission rate to increase or decrease by the delay limit determination means, and reaches the predetermined maximum round-trip delay time when the transmission rate increases as it is. Calculate time. This increase / decrease determination can be made based on the round trip delay time which is the difference between the transmission time of the packet and the reception time of the reception information corresponding to the packet and the packet identifier.
Then, the data transmission apparatus updates the maximum transmission rate within the limit time when it is determined by the maximum transmission rate calculation means that the temporary transmission rate exceeds the reception rate and the delay time determination means increases the transmission rate. To do.

  Further, the data transmission device according to claim 3 is the data transmission device according to claim 1, further comprising an update determination unit.

In such a configuration, the data transmission device determines whether or not to update the maximum transmission rate by the update determination unit. This update determination means holds the time when the maximum update rate is updated, and the round-trip delay time that is the difference between the transmission time of the packet and the reception time of the reception information corresponding to the packet and the packet identifier is a predetermined upper limit value. Whether or not the update is necessary is determined based on whether or not a predetermined time has elapsed since the time when the maximum update rate was updated.
The data transmission apparatus updates the maximum transmission rate when the maximum transmission rate calculation unit determines that the update determination unit updates the maximum transmission rate. This prevents the maximum transmission rate from being updated more than necessary.

  Furthermore, the data transmission device according to claim 4 is the data transmission device according to claim 1, further comprising a one-way delay limit determination means.

In such a configuration, the data transmission device acquires, from the data reception device, the reception side reception time, which is the time when the packet is received, in association with the packet identifier included in the packet by the reception information acquisition unit.
Then, the data transmission apparatus determines the tendency of the transmission rate to increase or decrease by the one-way delay limit determination means, and reaches the predetermined maximum one-way delay time when the transmission rate increases as it is. Calculate the limit time. This increase / decrease determination can be made based on the one-way delay time which is the difference between the packet transmission time and the reception side reception time when the packet is received by the data reception device.
Then, the data transmission apparatus determines the maximum transmission rate within the limit time when the temporary transmission rate exceeds the reception rate by the maximum transmission rate calculation means and the transmission rate increases by the one-way delay time determination means. Update.

  The data transmission device according to claim 5 is the data transmission device according to claim 1, wherein the packet transmission means adds a transmission time to the packet and transmits the packet to the data reception device, and the maximum transmission rate calculation means. Is received from the data receiving device based on a change in one-way delay time, which is a difference between the transmission time added to the packet and the reception side reception time in the data receiving device of the packet. As a notification that the transmission rate is to be updated, the maximum transmission rate is updated when the reception information is acquired.

  In such a configuration, the data transmission device is notified of reception information from the data reception device at a timing when it is determined that the maximum transmission rate needs to be updated based on the one-way delay time measured in the data reception device. Thus, the maximum transmission rate calculation means updates the maximum transmission rate. As a result, notification of reception information from the data receiving apparatus to the data transmitting apparatus can be reduced.

  A data reception device according to claim 6 is a data reception device that receives a packet from the data transmission device according to any one of claims 1 to 3, comprising: a packet reception unit; A rate measuring unit and a reception information notifying unit are provided.

In such a configuration, the data receiving device receives the packet from the data transmitting device by the packet receiving means. The received packets are sequentially output to the outside.
Further, the data receiving apparatus measures the reception rate of the packet received by the packet receiving means by the reception rate measuring means. Then, the data reception device transmits the reception rate measured by the reception rate measurement unit to the data transmission device as reception information in association with the packet identifier included in the packet by the reception information notification unit.
As a result, the data transmission device can measure the round-trip delay time, and can determine whether or not the maximum transmission rate has been updated.

  According to a seventh aspect of the present invention, there is provided a data receiving device for receiving a packet from the data transmitting device according to the fourth aspect, wherein the data receiving device includes a packet receiving means, a reception rate measuring means, and a reception information notifying means. And a configuration comprising:

In such a configuration, the data reception device receives the packet from the data transmission device by the packet reception means, and measures the time of reception as the reception side reception time. The received packets are sequentially output to the outside.
Further, the data receiving apparatus measures the reception rate of the packet received by the packet receiving means by the reception rate measuring means. The data reception device receives the reception rate measured by the reception rate measurement unit and the reception side reception time measured by the packet reception unit in association with the packet identifier included in the packet by the reception information notification unit. Information is transmitted to the data transmission device.
As a result, the data transmission apparatus can measure the one-way delay time in the packet transmission direction, and can determine whether or not the maximum transmission rate has been updated.

  Furthermore, the data receiving apparatus according to claim 8 is a data receiving apparatus that receives a packet from the data transmitting apparatus according to claim 5, and is a packet receiving means, a reception rate measuring means, and a round-trip delay measuring means. And a notification determination unit and a reception information notification unit.

In such a configuration, the data reception device receives the packet from the data transmission device together with its transmission time by the packet reception means, and measures the reception time as the reception side reception time. The received packets are sequentially output to the outside.
Further, the data receiving apparatus measures the reception rate of the packet received by the packet receiving means by the reception rate measuring means.
Further, the data receiving device transmits an echo request to the data transmitting device by the round trip delay measuring means, receives an echo response corresponding to the echo request, and measures the round trip delay time.

Then, the data reception device uses the notification determination unit to set a predetermined upper limit on the one-way delay time after the round-trip delay time has elapsed based on the amount of change in the one-way delay time, which is the difference between the transmission time and the reception side reception time. It is determined whether or not the data transmitting apparatus needs to be notified that the transmission rate is changed, depending on whether or not the value is reached.
When the data reception device determines that the transmission rate needs to be changed by the notification determination unit by the reception information notification unit, the data reception device measures the reception rate measured by the reception rate measurement unit. Are transmitted as received information to the data transmitting apparatus. Thereby, the data receiving apparatus can notify the timing when the data transmitting apparatus updates the maximum transmission rate.

  A data transmission device according to claim 9 is a data transmission device that transmits stream data as a packet including a packet identifier to a data reception device via a packet communication network, the data transmission device including: The transmission rate measurement unit, the packet transmission unit, the reception information acquisition unit, and the maximum transmission rate calculation unit are provided.

In such a configuration, the data transmission device encodes the stream data into packets by the data encoding means at a maximum transmission rate or less.
Then, the data transmission device measures the transmission rate of the packets that are sequentially transmitted by the transmission rate measuring means. This transmission rate can be regarded as the provisional transmission rate of the next packet to be transmitted.

In addition, the data transmission device transmits the packet generated by the data encoding unit to the data reception device by the packet transmission unit.
In addition, the data transmission apparatus acquires, as reception information, a reception rate when the packet is received, from the data reception apparatus, in association with the packet identifier included in the packet, by the reception information acquisition unit. As a result, the data transmission apparatus can recognize at what reception rate the packet is received by the data reception apparatus.

Then, the data transmission device calculates and updates the maximum transmission rate by the maximum transmission rate calculation means based on the temporary transmission rate and the reception rate corresponding to the packet identifier.
That is, when the temporary transmission rate exceeds the reception rate, the maximum transmission rate calculation means calculates a value obtained by subtracting the cross traffic usage band from the bottleneck link band as the maximum transmission rate. The use band of the cross traffic can be obtained as the amount of traffic added to the bottleneck link band from the ratio between the temporary transmission rate and the reception rate.
Further, the maximum transmission rate calculation means adds a predetermined rate increase amount to the maximum transmission rate when the provisional transmission rate is equal to or lower than the reception rate to obtain a new maximum transmission rate.

  Furthermore, the data receiving device according to claim 10 is a data receiving device that receives a packet from the data transmitting device according to claim 9, and includes a packet receiving means, a data decoding means, a reception rate measuring means, And reception information notification means.

In such a configuration, the data receiving device receives the packet from the data transmitting device by the packet receiving means. Then, the data receiving apparatus decodes the packet received by the packet receiving means into stream data by the data decoding means. The decoded stream data is sequentially output to the outside.
Further, the data receiving apparatus measures the reception rate of the packet received by the packet receiving means by the reception rate measuring means. Then, the data reception device transmits the reception rate measured by the reception rate measurement unit to the data transmission device as reception information in association with the packet identifier included in the packet by the reception information notification unit.
As a result, the data transmission device can measure the round-trip delay time, and can determine whether or not the maximum transmission rate has been updated.

The present invention has the following excellent effects.
According to the first and fifth aspects of the present invention, even when cross traffic flows into the network, the band can be estimated and the transmission rate can be controlled according to the band. As a result, even when a large amount of cross traffic flows on the network, the packet transmission rate is ensured. For example, even when video and audio are transmitted, the video and audio are distorted and frozen. Quality deterioration can be suppressed.

  According to the invention described in claim 2, in addition to the effect of the invention according to claim 1, the round-trip delay time of the packet can be suppressed within the maximum round-trip delay time, and the maximum transmission rate is set according to the delay time. It can be changed in stages. Thereby, the transmission efficiency of the network can be increased.

  According to the invention described in claim 3, in addition to the effect of the invention according to claim 1, the round-trip delay time of the packet can be suppressed within the maximum round-trip delay time, and the update of the maximum transmission rate can be minimized. The number of times can be reduced. As a result, the load on the data transmission device can be reduced.

  According to the invention described in claim 4, in addition to the effect of the invention according to claim 1, the one-way delay time of the packet can be suppressed within the maximum one-way delay time, and the maximum transmission is performed according to the delay time. The rate can be changed in steps. Thereby, the transmission efficiency of the network can be increased.

It is a block block diagram which shows the structure of the data transmission / reception system containing the data transmitter which concerns on 1st Embodiment of this invention, and a data receiver. It is explanatory drawing for demonstrating cross traffic. It is explanatory drawing for demonstrating the maximum transmission rate which considered the cross traffic. It is a flowchart which shows the packet transmission operation | movement of the data transmission / reception system which concerns on 1st Embodiment of this invention. It is a flowchart which shows the packet reception operation | movement of the data transmission / reception system which concerns on 1st Embodiment of this invention. It is a flowchart which shows the maximum transmission rate update operation | movement of the data transmission / reception system which concerns on 1st Embodiment of this invention. It is a block block diagram which shows the structure of the data transmission / reception system containing the data transmitter which concerns on 2nd Embodiment of this invention, and a data receiver. In 2nd Embodiment of this invention, it is explanatory drawing for demonstrating a round-trip delay time (RTT) and a limit time. In 2nd Embodiment of this invention, it is explanatory drawing for demonstrating the relationship between the present maximum transmission rate and the target maximum transmission rate. It is a flowchart which shows the maximum transmission rate update operation | movement of the data transmission / reception system which concerns on 2nd Embodiment of this invention. It is a block block diagram which shows the structure of the data transmission / reception system containing the data transmitter which concerns on 3rd Embodiment of this invention, and a data receiver. It is a flowchart which shows the maximum transmission rate update operation | movement of the data transmission / reception system which concerns on 3rd Embodiment of this invention. It is a block block diagram which shows the structure of the data transmission / reception system containing the data transmitter which concerns on 4th Embodiment of this invention, and a data receiver. It is a flowchart which shows the maximum transmission rate update operation | movement of the data transmission / reception system which concerns on 4th Embodiment of this invention. It is a block block diagram which shows the structure of the data transmission / reception system containing the data transmitter which concerns on 5th Embodiment of this invention, and a data receiver. In 5th Embodiment of this invention, it is explanatory drawing for demonstrating the time until it reaches the upper limit of one-way delay time. It is a flowchart which shows the packet transmission operation | movement of the data transmission / reception system which concerns on 5th Embodiment of this invention. It is a flowchart which shows the packet reception operation | movement of the data transmission / reception system which concerns on 5th Embodiment of this invention. It is a block block diagram which shows the structure of the data transmission / reception system containing the data transmitter which concerns on 6th Embodiment of this invention, and a data receiver.

Embodiments of the present invention will be described below with reference to the drawings.
<< First Embodiment >>
First, the data transmission / reception system S according to the first embodiment of the present invention will be described with reference to FIG.

<Outline of data transmission / reception system>
The data transmission / reception system S shown in FIG. 1 transmits data (packets) from a data input device A to a data output device B via a data transmission device 1 and a data reception device 2 in a packet communication network. .

The data input device A inputs data (packets) obtained by packetizing a data stream to the data transmission device 1. The data input device A is, for example, a PC (personal computer), a video encoding, or the like.
The data output device B acquires packetized data from the data receiving device 2. The data output device B is, for example, a PC, a moving picture decoder, or the like.

  The data transmission device 1 transmits data (packets) input from the data input device A to the data reception device 2 via the line L1. The data transmission device 1 has a function of estimating cross traffic and controlling the transmission rate of transmission data to be transmitted to the data reception device 2.

  The data receiving apparatus 2 receives transmission data from the data transmitting apparatus 1 via the line L1 and outputs it to the data output apparatus B. The data receiving apparatus 2 has a function of transmitting information (reception information) on the receiving side required when the data transmitting apparatus 1 estimates cross traffic to the data transmitting apparatus 1 via the line L2.

The line L1 is a packet communication line that transmits data in the direction from the data transmission apparatus 1 to the data reception apparatus 2. The line L2 is a packet communication line that transmits data in the direction from the data receiving apparatus 2 to the data transmitting apparatus 1. The line L1 and the line L2 may be wired or wireless. Further, the line L1 and the line L2 do not need to be physically separated, and may be lines that are logically separated on the physical line.
Hereinafter, the data transmission device 1 and the data reception device 2 according to the present invention will be described in detail with reference to FIG.

[Configuration of data transmission device]
As shown in FIG. 1, the data transmission device 1 includes a transmission rate measurement unit 10, a packet transmission unit 11, a reception information acquisition unit 12, and a maximum transmission rate determination unit 13.

The transmission rate measuring means 10 measures a transmission rate that is a transmission rate of a packet transmitted from the data transmission device 1. Here, the transmission rate measuring means 10 sequentially inputs the packet lengths of the packets transmitted by the packet transmitting means 11, and calculates the value obtained by dividing the packet length transmitted within the latest fixed time by the fixed time as the transmission rate.
The transmission rate measured by the transmission rate measuring unit 10 is a temporary transmission rate when the packet transmitting unit 11 transmits a packet. This transmission rate is output to the packet transmission unit 11.

The packet transmission means 11 transmits the data (packet) input from the data input device A to the data reception device 2 via the line L1.
Here, the packet transmission unit 11 outputs the packet length to the transmission rate measurement unit 10 when transmitting the input packet to the data reception device 2, and also transmits the identifier (packet identifier) of the transmitted packet and the transmission rate (temporary). Output to the maximum transmission rate determination means 13.

  As the packet identifier, for example, if the packet is an IP packet, the value of the identifier (Identification) in the IP header can be used. If the packet is an RTP (Real-time Transport Protocol) packet defined by RFC3550, the sequence number in the RTP header can be used.

When the transmission rate measured by the transmission rate measuring unit 10 exceeds the maximum transmission rate output from the maximum transmission rate determining unit 13, the packet transmitting unit 11 discards the input packet without transmitting it.
Then, the packet transmission unit 11 notifies the data input device A of the success or failure of whether or not the input packet has been transmitted to the data receiving device 2 as a transmission result.

The reception information acquisition unit 12 receives, as reception information when the data reception device 2 receives a packet, an identifier (packet identifier) of the received packet and a transmission rate when the data reception device 2 receives the packet. The rate is acquired via the line L2. Note that this reception information can be acquired from the data reception device 2 by describing the information in an RTCP (RTP Control Protocol) packet, for example, when transmitting and receiving a packet by RTP.
The reception information acquisition unit 12 outputs the acquired reception information (packet identifier, reception rate) to the maximum transmission rate determination unit 13.

  The maximum transmission rate determining means 13 determines the maximum transmission rate based on the transmission rate and the reception rate. In the initial stage where the transmission rate and the reception rate are not specified, the maximum transmission rate is a predetermined value. Here, the maximum transmission rate determination unit 13 includes a maximum transmission rate calculation unit 13a.

The maximum transmission rate calculation means 13a determines the bandwidth of the bottleneck link (bottleneck) based on the provisional transmission rate when the packet transmission means 11 transmits the packet and the actual reception rate acquired by the reception information acquisition means 12. The maximum transmission rate that can be transmitted by subtracting the cross traffic bandwidth from the physical bandwidth is calculated.
Here, the bottleneck link is a line between nodes having the narrowest bandwidth on the line L1 on the transmission side between the data transmission apparatus 1 and the data reception apparatus 2.
Here, the maximum transmission rate calculation unit 13a acquires the packet identifier and the transmission rate (temporary transmission rate) from the packet transmission unit 11, and stores them in a storage unit (not shown). The maximum transmission rate calculation unit 13a acquires the packet identifier and the reception rate from the reception information acquisition unit 12, and the ratio between the transmission rate stored corresponding to the same packet identifier and the corresponding reception rate Based on the above, the maximum transmission rate is calculated.

Specifically, the maximum transmission rate calculation means 13a sets the current maximum transmission rate to S _max (bps), the temporary transmission rate corresponding to the packet identifier to S (bps), the reception rate to R (bps), and the line L1. When the bottleneck physical band of B is B (bps), the maximum transmission rate is calculated and updated as shown in the following equation (1).

That is, when the reception rate R is lower than the transmission rate S (R <S), the maximum transmission rate calculation means 13a calculates a value obtained by subtracting the cross traffic band from the bottleneck link band (bottleneck physical band B). A new maximum transmission rate S _max is set. When the reception rate R is equal to or higher than the transmission rate S (S ≦ R), the maximum transmission rate is increased by a predetermined rate (rate increase amount). The rate increase amount is not particularly limited. For example, the rate increase amount is a value obtained by multiplying a predetermined maximum packet length by a unit time and a constant increase rate (> 0).

In addition, the update of the maximum transmission rate does not need to be strictly divided based on the provisional transmission rate S and the reception rate R as in the equation (1), and may allow a certain amount of error. .
For example, α (0 ≦ α) is a parameter for determining an allowable amount of error (β ≦ 0), β (0 <β) is a parameter for determining a rate increase rate (0 <β), and the maximum packet length is specified in advance. Is the MTU and T is the unit time for calculating the rate, the maximum transmission rate calculation means 13a may calculate and update the maximum transmission rate by the following equation (2).

The bottleneck physical band B may be set in advance as a bottleneck link band if the line L1 is a known line. If the line L1 is an unknown line, the bottleneck physical band B may be set before or during transmission of a packet. It is good also as estimating and using that value. The bottleneck physical band can be estimated by using a general method such as the PacketPair method ("A Control-Theoretic Approach to Flow Control," S. Keshav (ACM SIGCOMM, pp. 3-15, 1991). In this Packet tPair method, a continuous packet pair is transmitted, and a bottleneck physical band is estimated from a difference in arrival time of each packet.
The maximum transmission rate calculation unit 13a stores the calculated maximum transmission rate in a storage unit (not shown), and sequentially refers to it when the packet transmission unit 11 transmits a packet.

Here, with reference to FIG. 2 and FIG. 3, it will be explained that the maximum transmission rate calculation means 13a can calculate the maximum transmission rate by the equation (1).
2 transmits the packet P ₁ from the data transmitting apparatus 1 ₁ to the data receiving apparatus 2 _1, it shows how to send a packet P ₂ from the data transmission device 1 ₂ to the data receiving apparatus 2 _2. Here, it is assumed that packets are transmitted on the same link between certain nodes N ₁ and N ₂ .

At this time, in the path from the data transmission device 1 ₁ to the data receiving apparatus 2 _1, packet P ₂ flowing from the data transmission device 1 ₂ to the data receiving apparatus 2 ₂ is a cross traffic. In the case where mainly the path from the data transmitter 1 ₂ to the data receiving apparatus 2 _2, packet P ₁ flowing from the data transmission device 1 ₁ to the data reception device 2 ₁ is cross traffic.

Here, as shown in FIG. 3, the transmission rate from the data transmission device 1 ₁ S, the band (bottleneck physical bandwidth) in between the nodes N _1, N ₂ as a bottleneck link B, and cross traffic X When the reception rate of the data receiving apparatus 2 ₁ and R, it is satisfied the following equation (3) relationship.

  That is, the cross traffic X can be obtained by the following equation (4).

Therefore, the maximum transmission rate S _max that does not transmit a packet exceeding the bottleneck physical band B between the nodes N ₁ and N ₂ is calculated from the bottleneck physical band B as shown in the following equation (5). A value obtained by subtracting X may be used.

By substituting X in the equation (4) into the equation (5), the maximum transmission rate S _max shown in the equation (1) can be obtained.
Returning to FIG. 1, the description will be continued.

  As described above, the maximum transmission rate determination means 13 can estimate the cross traffic and determine the transmission rate within a range not exceeding the bottleneck physical band. Thereby, the packet transmission means 11 can transmit a packet within the range which does not exceed a bottleneck physical band, without being influenced by the amount of cross traffic.

  Here, the packet is transmitted from the packet transmission unit 11 to the data receiving device 2, but the packet may be transmitted from the data input device A to the data receiving device 2. In this case, the packet identifier and the packet length are notified from the data input device A to the packet transmission unit 11 of the data transmission device 1, and the packet transmission unit 11 determines whether or not the packet transmission unit 11 can transmit to the line L1. Notify A. Based on the determination result, the data input device A transmits a packet to the line L1.

[Configuration of data receiver]
Next, the configuration of the data receiving device 2 will be described with reference to FIG. As shown in FIG. 1, the data reception device 2 includes a packet reception unit 20, a reception rate measurement unit 21, and a reception information notification unit 22.

The packet receiving means 20 receives transmission data (packets) from the data transmitting apparatus 1 via the line L1 and outputs it to the data output apparatus B.
Here, the packet receiving unit 20 outputs the received packet identifier (packet identifier) and the data length (packet length) of the packet to the reception rate measuring unit 21. Further, the packet receiving unit 20 measures the time (reception side reception time) when the packet is received by a timing unit (not shown), and outputs it to the reception rate measuring unit 21.

The reception rate measuring unit 21 measures a reception rate that is a transmission rate of the packet received by the packet receiving unit 20.
Here, the reception rate measuring unit 21 calculates the reception rate based on the packet length input from the packet receiving unit 20 and the reception side reception time. For example, the reception rate measuring unit 21 sets the value obtained by dividing the packet length by the difference between the reception side reception time of the previously received packet and the current reception side reception time. Alternatively, the reception rate measuring means 21 may obtain the reception rate by dividing the total number of packet lengths received in a certain time length by the time length.
The reception rate measuring unit 21 outputs the measured reception rate to the reception information notifying unit 22 together with the packet identifier input from the packet receiving unit 20.

The reception information notification unit 22 receives the packet identifier and the reception rate from the reception rate measurement unit 21 and transmits (notifies) the received information to the data transmission device 1 via the line L2. For the notification of the packet identifier and the reception rate, for example, an RTCP packet can be used.
Thus, the reception information notification means 22 notifies the data transmission device 1 of the reception rate together with the packet identifier, so that the data transmission device 1 can estimate cross traffic.

As described above, since the data transmission / reception system S can change the transmission rate according to the size of the cross traffic, the bandwidth of the bottleneck link can be obtained even when a large amount of cross traffic flows on the line. Data transmission can be performed within the network.
For this reason, the data receiving device 2 can continuously receive data. For example, even when the data output device B reproduces a moving image, the moving image reproduction does not stop.

<Operation of data transmission / reception system>
Next, operations of the data transmission / reception system S according to the first embodiment of the present invention will be described with reference to FIGS.

[Packet transmission operation]
First, the packet transmission operation in the data transmission device 1 will be described with reference to FIG. 4 (refer to FIG. 1 as appropriate).
First, the data transmission device 1 inputs a packet from the data input device A by the packet transmission means 11 (step S1).
Then, the data transmission device 1 uses the transmission rate measuring means 10 to calculate a provisional transmission rate for transmitting the packet from the data length of the transmission data within the latest fixed time including the packet length of the packet to be transmitted this time. (Step S2).
When the temporary transmission rate calculated in step S2 is less than the maximum transmission rate determined by the maximum transmission rate determination unit 13 (Yes in step S3), the packet transmission unit 11 determines the packet input in step S1. Then, the data is transmitted to the data receiving device 2 via the line L1 (step S4).

Then, the packet transmission unit 11 outputs the packet identifier of the packet transmitted in step S4 and the temporary transmission rate calculated in step S2 to the maximum transmission rate determination unit 13 (step S5). The packet identifier and the transmission rate are information on the transmission side when the maximum transmission rate determining means 13 calculates the maximum transmission rate.
On the other hand, when the temporary transmission rate is equal to or higher than the maximum transmission rate (No in step S3), the packet transmission unit 11 discards the packet input in step S1 (step S6).
Then, the packet transmission unit 11 notifies the data input device A of the transmission result indicating whether the packet has been transmitted (step S7).

[Packet reception operation]
Next, referring to FIG. 5 (refer to FIG. 1 as appropriate), the packet receiving operation in the data receiving apparatus 2 will be described.
First, the data reception device 2 receives a packet from the data transmission device 1 via the line L1 by the packet reception means 20 (step S10).
Then, the packet receiving unit 20 outputs the received packet to the data output device B (step S11).
Further, the data receiving device 2 calculates the reception rate by the reception rate measuring means 21 based on the packet length of the packet received in step S10 and the time when the packet is received (reception time on the reception side) (step S1). S12).

Then, the data receiving apparatus 2 uses the reception information notifying means 22 as a reception information, using the packet identifier of the packet received in step S10 and the reception rate calculated in step S12, via the line L2, as the data transmitting apparatus 1 Is transmitted (notified) to (step S13).
The packet identifier and the reception rate, which are reception information, are information on the reception side when the maximum transmission rate is calculated in the maximum transmission rate determination means 13 of the data transmission apparatus 1.

[Maximum transmission rate update operation]
Next, the maximum transmission rate update operation in the data transmission device 1 will be described with reference to FIG.
First, the data transmission device 1 acquires the packet identifier and the reception rate, which are reception information, from the data reception device 2 via the line L2 by the reception information acquisition unit 12 (step S20).

Then, the data transmission device 1 acquires the packet identifier and the provisional transmission rate input from the packet transmission unit 11 in step S5 of FIG. 4 and the maximum transmission rate calculation unit 13a of the maximum transmission rate determination unit 13 in step S20. Based on the packet identifier and the reception rate, using the transmission rate and the reception rate corresponding to the same packet identifier, the maximum transmission rate is calculated by the equation (1) and updated (step S21).
Based on the maximum transmission rate calculated in step S21, the data transmitting apparatus 1 determines whether or not the packet can be transmitted in step S3 of FIG.

<< Second Embodiment >>
Next, with reference to FIG. 7, the data transmitting and receiving system S _B according to the second embodiment of the present invention.

<Outline of data transmission / reception system>
Data transmitting and receiving system S _B shown in FIG. 7, in a packet communication network, intended to transmit from the data input device A to the data output device B, and via a data transmission device 1B and the data receiving apparatus 2 data (packet) Basically, it has the same function as the data transmission / reception system S described in FIG.
Further, the data transmission and reception system S _B, in the data transmission apparatus 1B, the round trip time of the packet (Round Trip Time: hereinafter referred RTT) measured, so as not to exceed the time that the RTT is predetermined, the delay of packets It has a function to control.
The data receiving apparatus 2 in a data transmission and reception system S _B, because it is the same as the data transmitting and receiving system S described in FIG 1, here, a description is given of the data transmission apparatus 1B only.

[Configuration of data transmission device]
As shown in FIG. 7, the data transmission device 1B includes a transmission rate measurement unit 10, a packet transmission unit 11B, a reception information acquisition unit 12B, and a maximum transmission rate determination unit 13B. Since the transmission rate measuring means 10 is the same as the configuration of the data transmitting apparatus 1 described in FIG.

  The packet transmission unit 11B basically has the same function as the packet transmission unit 11 described with reference to FIG. 1, but further has a function of measuring the time (transmission time) at which the packet is transmitted and outputting it to the maximum transmission rate determination unit 13B. Is added.

The reception information acquisition unit 12B basically has the same function as the reception information acquisition unit 12 described in FIG. 1, but further measures the time (reception time) at which reception information (packet identifier, reception rate) is received, A function of outputting to the maximum transmission rate determining means 13B is added.
The packet transmission unit 11B and the reception information acquisition unit 12B measure the time when the packet is transmitted and the time when the reception information is received by the time measurement unit (not shown).

  The maximum transmission rate determination means 13B determines the maximum transmission rate based on the transmission rate, the reception rate, and the round trip delay time of the packet. Here, the maximum transmission rate determination unit 13B includes a maximum transmission rate calculation unit 13Ba and a delay limit determination unit 13b.

First, the delay limit determination means 13b will be described.
The delay limit judging means 13b increases or decreases the round-trip delay time (RTT) of the packet, which is the difference between the packet transmission time and the reception time of the corresponding reception information, that is, the delay time increases (increases). It is determined whether it is in a tendency) or in a decreasing direction (decreasing tendency). Furthermore, when the RTT tends to increase, the delay limit determination unit 13b calculates a time (limit time) until the RTT reaches a predetermined upper limit value of the RTT.

The delay limit determination means 13b obtains the packet transmission time and reception time from the maximum transmission rate calculation means 13Ba, determines the increase or decrease of the RTT, and further increases the limit time if there is a tendency to increase. Output to the transmission rate calculation means 13Ba.
That is, as shown in FIG. 8, the delay limit determination unit 13b sequentially records RTT in a memory or the like, and when the RTT tends to increase at the current time, the RTT increases at that rate and the RTT reaches the upper limit. The time to reach is notified to the maximum transmission rate calculation means 13Ba as the limit time.

Note that the delay limit determination unit 13b may determine the RTT change (increase or decrease) tendency based on the RTT change amount per unit time. For example, the delay limit determination means 13b sequentially stores the RTT by smoothing it with an exponential weighted moving average and stores it in correspondence with the transmission time, and subtracts the RTT corresponding to the previous transmission time from the RTT calculated at the new transmission time. The amount of change per unit time of RTT is calculated by dividing by the difference in transmission time. Then, the delay limit determination means 13b determines that the change amount is positive if the change amount is positive, and the decrease trend if the change amount is negative.
Further, the delay limit determination means 13b can obtain the limit time shown in FIG. 8 by using the change amount of RTT per unit time.

The maximum transmission rate calculation means 13Ba includes the provisional transmission rate when the packet is transmitted by the packet transmission means 11B, the actual reception rate acquired by the reception information acquisition means 12B, and the determination result (limit time) of the delay limit determination means 13b. The maximum transmission rate is calculated based on the above.
Here, the maximum transmission rate calculation means 13Ba receives the packet identifier, the transmission rate and the transmission time from the packet transmission means 11B, and inputs the packet identifier, the reception rate and the reception time from the reception information acquisition means 12B.
Then, the maximum transmission rate calculation means 13Ba outputs the transmission time and the reception time corresponding to the same packet identifier to the delay limit determination means 13b. From the delay limit determination means 13b, the determination result of the change in RTT (the limit time may be included). ) To calculate the maximum transmission rate.

  Specifically, when the RTT tends to increase and the transmission rate corresponding to the packet identifier exceeds the reception rate, the maximum transmission rate calculation means 13Ba calculates the target maximum transmission according to the above equation (1). The rate is calculated, and the maximum transmission rate is updated to the target maximum transmission rate by using a value obtained by dividing the difference from the current maximum transmission rate by the limit time as a decrease rate per unit time. That is, as shown in FIG. 9, the maximum transmission rate is continuously decreased so that the current maximum transmission rate becomes the target maximum transmission rate at the limit time.

  When the maximum transmission rate calculation means 13Ba is notified of other reception information from the reception information acquisition means 12B while continuously decreasing the maximum transmission rate, the target maximum transmission rate at that time, the decrease Information such as speed and limit time is invalidated, and the maximum transmission rate is calculated based on a determination result (which may include a limit time) newly determined by the delay limit determination means 13b.

Further, the maximum transmission rate calculation means 13Ba performs maximum transmission when the RTT tends to increase and the transmission rate is equal to or lower than the reception rate, or when the RTT does not tend to increase and the transmission rate exceeds the reception rate. Maintain rate.
Further, when the RTT does not tend to increase and the transmission rate is equal to or lower than the reception rate, the maximum transmission rate calculation unit 13Ba sets the maximum transmission rate by a predetermined rate increase amount according to the lower expression of the expression (1). increase.

As described above, the maximum transmission rate determination means 13B can estimate the cross traffic and determine the transmission rate within a range not exceeding the bottleneck physical bandwidth, and the packet delay does not exceed the predetermined delay time. In addition, the transmission rate can be determined.
As described above, data transmitting and receiving system S _B may be added to the characteristics of the data transmission and reception system S described in FIG 1, it is controlled so that the transmission time of the packet does not exceed a predetermined delay time or more.

<Operation of data transmission / reception system>
Next, with reference to FIG. 10, the operation of the data transmission system S _B according to the second embodiment of the present invention.
Note that in the packet transmission operation, an operation for measuring the time (transmission time) at which the packet was transmitted is added in step S4 of the packet transmission operation described in FIG. 4, and in step S5, the transmission is performed in addition to the packet identifier and the transmission rate. The only difference is that the time is output to the maximum transmission rate determining means 13.
The packet transmission operation is the same as the operation described in FIG.
Therefore, only the maximum transmission rate update operation will be described here.

[Maximum transmission rate update operation]
Hereinafter, the maximum transmission rate update operation in the data transmission apparatus 1B will be described with reference to FIG. 10 (refer to FIG. 7 as appropriate).
First, the data transmission apparatus 1B acquires the packet identifier and the reception rate, which are reception information, from the data reception apparatus 2 through the line L2 by the reception information acquisition unit 12B (step S30). At this time, the reception information acquisition unit 12B measures the time when the reception information is acquired as the reception time corresponding to the packet identifier.
Then, the data transmission device 1B has a tendency that the round trip delay time (RTT) of the packet, which is a difference between the transmission time of the packet and the reception time of the reception information corresponding thereto, is increasing by the delay limit determination unit 13b, or Then, it is determined whether or not there is a decreasing tendency (step S31).

Here, when it is determined that the RTT has an increasing tendency (Yes in step S31), the delay limit determining means 13b further reaches the predetermined upper limit value when the RTT increases at an increasing tendency rate. The time is calculated as the limit time (step S32).
Furthermore, when the transmission rate exceeds the reception rate (Yes in step S33), the data transmission device 1B uses the maximum transmission rate calculation means 13Ba to calculate the target maximum transmission according to the above equation (1). The rate is calculated, and the maximum transmission rate is continuously decreased to the target maximum transmission rate using a value obtained by dividing the difference from the current maximum transmission rate by the limit time as a decrease rate per unit time (step S34). If the transmission rate is equal to or lower than the reception rate (No in step S33), the maximum transmission rate calculation unit 13Ba maintains the maximum transmission rate (step S35).

  On the other hand, if it is determined that the RTT does not tend to increase (No in step S31), and if the transmission rate exceeds the reception rate (Yes in step S36), the maximum transmission rate calculation means 13Ba sets the maximum transmission rate. Maintain (step S35). If the transmission rate is equal to or lower than the reception rate (No in step S36), the maximum transmission rate calculation means 13Ba increases the maximum transmission rate by a predetermined rate increase amount according to the lower expression of the expression (1). (Step S37).

«Third embodiment»
Next, referring to FIG. 11, a description will be given of a data transmission and reception system S _C according to a third embodiment of the present invention.

<Outline of data transmission / reception system>
Data transmitting and receiving system S _C shown in FIG. 11, in the packet communication network, intended to transmit from the data input device A to the data output device B, and via a data transmission apparatus 1C and the data receiving apparatus 2 data (packet) Basically, it has the same function as the data transmission / reception system S described in FIG.
Further, the data transmission and reception system S _C so as not to exceed the time that the RTT is predetermined, and has a function of controlling the delay of a packet has a function to minimize the update of the maximum transmission rate.
The data receiving apparatus 2 in a data transmission and reception system S _C, because it is the same as the data transmitting and receiving system S described in FIG 1, here, a description is given of the data transmission apparatus 1C only.

[Configuration of data transmission device]
As shown in FIG. 11, the data transmitting apparatus 1C includes a transmission rate measuring unit 10, a packet transmitting unit 11B, a reception information acquiring unit 12B, and a maximum transmission rate determining unit 13C. Since the configuration other than the maximum transmission rate determining means 13C is the same as the configuration of the data transmitting apparatus 1B described with reference to FIG. 2, the same reference numerals are given and description thereof is omitted.

The maximum transmission rate determination means 13C determines the maximum transmission rate based on the transmission rate and the reception rate. In addition, when updating the maximum transmission rate, the maximum transmission rate determination unit 13C updates the maximum update rate based on the RTT value and the elapsed time from the update time of the last updated maximum transmission rate. It has a function to control whether or not.
Here, the maximum transmission rate determination unit 13C includes a maximum transmission rate calculation unit 13Ca and an update determination unit 13c.

The maximum transmission rate calculation means 13Ca calculates the maximum transmission rate based on the provisional transmission rate when the packet is transmitted by the packet transmission means 11B and the actual reception rate acquired by the reception information acquisition means 12B. is there. The maximum transmission rate calculation unit 13Ca receives the determination result as to whether or not the update of the maximum transmission rate is necessary in the update determination unit 13c, and updates the maximum transmission rate only when it is determined that the update is necessary. .
Here, the maximum transmission rate calculation unit 13Ca acquires the packet identifier, the transmission rate, and the transmission time from the packet transmission unit 11B, and acquires the packet identifier, the reception rate, and the reception time from the reception information acquisition unit 12B.
Then, the maximum transmission rate calculation unit 13Ca outputs the transmission time and the reception time corresponding to the same packet identifier to the update determination unit 13c, and obtains a determination result indicating that the maximum transmission rate needs to be updated from the update determination unit 13c. In this case, the maximum transmission rate is calculated and updated by the calculation formula shown in the formula (1).

The update determination unit 13c includes a round-trip delay time (RTT) that is a difference between the transmission time of the packet and the reception time of the corresponding reception information, and the elapsed time from the time when the update of the maximum transmission rate was finally determined. Based on the above, it is determined whether or not the maximum transmission rate needs to be updated. This determination result is output to the maximum transmission rate calculation means 13Ca.
Here, the update determination means 13c is at least one of whether the RTT has reached the RTT upper limit value, or whether the elapsed time from the time when the maximum transmission rate was last updated has passed the rate update maximum interval time If the above condition is satisfied, it is determined that the maximum transmission rate needs to be updated.

Here, the RTT can be calculated by subtracting the transmission time of the packet with the same packet identifier from the reception time of the reception information. Moreover, a predetermined value can be used for the RTT upper limit value and the rate update maximum interval time. It should be noted that the maximum rate update interval time may be a variable time that changes at a predetermined rate so that it is shorter as the RTT value is larger and longer as the RTT value is smaller.
Thus, the maximum transmission rate determination means 13C can suppress the update frequency of the maximum transmission rate within a range where the RTT does not reach the upper limit value.

As described above, data transmitting and receiving system S _C, in addition to the characteristics of the data transmission and reception system S described in FIG 1, by reducing the update frequency of the maximum transmission rate, it is possible to reduce the load in the apparatus.

<Operation of data transmission / reception system>
Next, referring to FIG. 12, the operation of the data transmission system S _C according to a third embodiment of the present invention. Note that the packet transmission operation and the packet reception operation are the same as those of the data transmission / reception system S _B (FIG. 7), and thus description thereof is omitted.

[Maximum transmission rate update operation]
Hereinafter, the maximum transmission rate update operation in the data transmission device 1C will be described with reference to FIG. 12 (refer to FIG. 11 as appropriate).
First, the data transmission apparatus 1C acquires the packet identifier and the reception rate, which are reception information, from the data reception apparatus 2 via the line L2 by the reception information acquisition unit 12B (step S40). At this time, the reception information acquisition unit 12B measures the time when the reception information is acquired as the reception time corresponding to the packet identifier.

Then, the data transmission device 1C uses the update determination unit 13c to determine that the round trip delay time (RTT) of the packet, which is the difference between the transmission time of the packet and the reception time of the corresponding reception information, has reached a predetermined upper limit value. Or whether the elapsed time from the time at which the maximum transmission rate was last updated has passed a predetermined rate update maximum interval time (step S41).
In step S41, when at least one of the two conditions is satisfied (Yes in step S41), the update determination unit 13c notifies the maximum transmission rate calculation unit 13Ca of a determination result indicating that the maximum transmission rate needs to be updated. The maximum transmission rate calculation means 13Ca calculates and updates the maximum transmission rate according to the equation (1) (step S42).

  On the other hand, when the RTT is less than the upper limit value and the maximum rate update interval time has not elapsed since the last time the maximum transmission rate was updated (No in step S41), the update determination unit 13c needs to be updated. The maximum transmission rate is maintained by notifying the maximum transmission rate calculation means 13Ca of the determination result that there is no (step S43).

<< Fourth Embodiment >>
Next, a data transmission / reception system _{SD according} to the fourth embodiment of the present invention will be described with reference to FIG.

<Outline of data transmission / reception system>
The data transmission / reception system _SD shown in FIG. 13 transmits data (packets) from a data input device A to a data output device B via a data transmission device 1D and a data reception device 2D in a packet communication network. Basically, it has the same function as the data transmission / reception system S described in FIG.
Further, the data transmission / reception system _SD has a function of controlling packet delay.

In the data transmission system S _B described in FIG. 7, as the delay time of a packet, from the transmission of the packet, the time to acquire the reception information corresponding to the packet, i.e. reciprocating bidirectional lines L1, L2 Delay time (RTT) was used. However, in the data transmission / reception system _SD , as a delay time, a time until a packet is transmitted and received, that is, a one-way (transmission direction) delay time of only the line L1 is used.
Hereinafter, the data transmission device 1D and the data reception device 2D according to the present invention will be described in detail with reference to FIG.

[Configuration of data transmission device]
As shown in FIG. 13, the data transmission device 1D includes a transmission rate measurement unit 10, a packet transmission unit 11B, a reception information acquisition unit 12D, and a maximum transmission rate determination unit 13D. The transmission rate measuring means 10 is the same as the configuration of the data transmitting apparatus 1 described in FIG. 1, and the packet transmitting means 11B is the same as the configuration of the data transmitting apparatus 1B described in FIG. The reference numerals are attached and the description is omitted.

  The reception information acquisition unit 12D basically has the same function as the reception information acquisition unit 12 described with reference to FIG. 1. However, the reception side reception time acquired as reception information in addition to the packet identifier and the reception rate is further transmitted to the maximum transmission. A function for outputting to the rate determining means 13D is added.

  The maximum transmission rate determination means 13D determines the maximum transmission rate based on the transmission rate, the reception rate, and the one-way (transmission direction) delay time of the packet. Here, the maximum transmission rate determination unit 13D includes a maximum transmission rate calculation unit 13Da and a delay limit determination unit 13Db.

First, the delay limit determination means 13Db will be described.
The delay limit determination means (one-way delay limit determination means) 13Db is a packet one-way (transmission direction) delay time which is the difference between the packet transmission time and the reception time (reception-side reception time) of the packet. Is in an increasing direction (increasing tendency) or in a decreasing direction (decreasing tendency). Furthermore, when the one-way delay time tends to increase, the delay limit determination unit 13Db calculates a time (limit time) until the one-way delay time reaches a predetermined upper limit value.

This delay limit determination means 13Db receives the packet transmission time and reception side reception time from the maximum transmission rate calculation means 13Da, and further determines if the one-way delay time increases or decreases, and if there is a tendency to increase. The limit time is output to the maximum transmission rate calculation means 13Da.
That is, the delay limit determination means 13b described in FIG. 7 determines a change in the round trip delay time (RTT), whereas the delay limit determination means 13Bb differs in that RTT is replaced with a one-way delay time. However, the delay time determination method and the limit time calculation method are the same.

The maximum transmission rate calculation means 13Da is a temporary transmission rate when the packet is transmitted by the packet transmission means 11B, the actual reception rate acquired by the reception information acquisition means 12D, and the determination result (limit time) of the delay limit determination means 13Db. The maximum transmission rate is calculated based on the above.
Here, the maximum transmission rate calculation unit 13Da acquires the packet identifier, the transmission rate, and the transmission time from the packet transmission unit 11B, and measures the packet identifier, the reception rate, and the data reception device 2D from the reception information acquisition unit 12D. The reception side reception time that is the reception time of the received packet is acquired.

  Then, the maximum transmission rate calculation means 13Da outputs the transmission time and reception side reception time corresponding to the same packet identifier to the delay limit determination means 13Db, and from the delay limit determination means 13Bb, a determination result (limit) Time may be included) and the maximum transmission rate is calculated.

  That is, the maximum transmission rate calculation unit 13Ba described in FIG. 7 calculates the maximum transmission rate according to the determination result of whether or not the RTT tends to increase, whereas the maximum transmission rate calculation unit 13Da includes the one-way delay time. The only difference is that the maximum transmission rate is calculated in accordance with the determination result of whether or not there is a tendency to increase.

  As described above, the maximum transmission rate determining means 13D can estimate the cross traffic, determine the transmission rate within a range not exceeding the bottleneck physical band, and determine a delay (one-way delay) in packet transmission in advance. The transmission rate can be determined so as not to exceed the delay time.

[Configuration of data receiver]
Next, the configuration of the data receiving device 2D will be described with reference to FIG. As shown in FIG. 13, the data receiving device 2D includes a packet receiving unit 20, a reception rate measuring unit 21D, and a reception information notification unit 22D. The packet receiving means 20 has the same configuration as that of the data receiving apparatus 2 described in FIG.

  The reception rate measuring unit 21D basically has the same function as the reception rate measuring unit 21 described with reference to FIG. 1, but further outputs a reception side reception time input from the packet receiving unit 20 to the reception information notification unit 22D. Is added.

The reception information notification unit 22D basically has the same function as the reception information notification unit 22 described with reference to FIG. 1, except that the reception side reception time input from the reception rate measurement unit 21D is data together with the packet identifier and the reception rate. A function of transmitting (notifying) to the transmitting apparatus 1D is added.
As a result, the data transmission device 1D can measure the delay time (one-way delay time) of the packet transmitted by the data transmission device 1D.

As described above, in addition to the characteristics of the data transmission / reception system S described in FIG. 1, the data transmission / reception system _SD can be controlled so that the transmission time in the packet transmission direction does not exceed a predetermined delay time. .

<Operation of data transmission / reception system>
Next, the operation of the data transmission / reception system _{SD according} to the fourth embodiment of the present invention will be described with reference to FIG.
Note that the packet transmission operation is the same as that of the data transmission / reception system S _B (FIG. 7), and a description thereof will be omitted.
In addition, in the packet transmission operation, in step S10 of the packet reception operation described with reference to FIG. 5, an operation of measuring the time of reception of the packet (reception time on the reception side) is added. The only difference is that the reception side reception time is notified as reception information.
Therefore, only the maximum transmission rate update operation will be described here.

[Maximum transmission rate update operation]
Hereinafter, the maximum transmission rate update operation in the data transmission device 1D will be described with reference to FIG. 14 (refer to FIG. 13 as appropriate).
First, the data transmission device 1D acquires the packet identifier, the reception rate, and the reception side reception time as reception information from the data reception device 2D through the line L2 by the reception information acquisition unit 12D (step S50).

Then, the data transmission device 1D causes the delay limit determination unit 13Db to increase the one-way delay time of the packet, which is the difference between the transmission time of the packet and the reception time of the reception information corresponding thereto, or Then, it is determined whether or not there is a decreasing tendency (step S51).
Here, when it is determined that the one-way delay time is increasing (Yes in step S51), the delay limit determination means 13Db further determines when the one-way delay time increases at a rate of increasing tendency. The time required to reach the upper limit value is calculated as the limit time (step S52).

  Furthermore, when the transmission rate exceeds the reception rate (Yes in step S53), the data transmission device 1D uses the maximum transmission rate calculation means 13Da to calculate the target maximum transmission according to the upper equation of the equation (1). The rate is calculated, and the maximum transmission rate is continuously decreased to the target maximum transmission rate by using a value obtained by dividing the difference from the current maximum transmission rate by the limit time as a decrease rate per unit time (step S54). When the transmission rate is equal to or lower than the reception rate (No in step S53), the maximum transmission rate calculation unit 13Da maintains the maximum transmission rate (step S55).

  On the other hand, if it is determined that the one-way delay time does not tend to increase (No in step S51), and if the transmission rate exceeds the reception rate (Yes in step S56), the maximum transmission rate calculation means 13Da The transmission rate is maintained (step S55). If the transmission rate is equal to or lower than the reception rate (No in step S56), the maximum transmission rate calculation unit 13Da increases the maximum transmission rate by a predetermined rate increase amount according to the lower expression of the expression (1). (Step S57).

«Fifth embodiment»
Next, referring to FIG. 15, a description will be given of a data transmission and reception system S _E according to a fifth embodiment of the present invention.

<Outline of data transmission / reception system>
Data transmitting and receiving system S _E shown in FIG. 15, in the packet communication network, intended to transmit from the data input device A to the data output device B, and via a data transmission apparatus 1E and the data receiving apparatus 2E data (packet) Basically, it has the same function as the data transmission / reception system S described in FIG.
Further, the data transmission and reception system S _E has the data receiving apparatus 2E, measures the delay time of the packet, so as not to exceed the time that the delay time is predetermined, the function of controlling the delay of the packet.
Hereinafter, the data transmission device 1E and the data reception device 2E according to the present invention will be described in detail with reference to FIG.

[Configuration of data transmission device]
As shown in FIG. 15, the data transmission device 1E includes a transmission rate measurement unit 10, a packet transmission unit 11E, a reception information acquisition unit 12, a maximum transmission rate determination unit 13, and a round-trip delay response unit 14. ing. The transmission rate measuring means 10, the reception information acquiring means 12, and the maximum transmission rate determining means 13 are the same as the configuration of the data transmitting apparatus 1 described in FIG.

The packet transmission unit 11E basically has the same function as the packet transmission unit 11 described with reference to FIG. 1, but further has a function of adding the transmission time of the packet (transmission time) to the transmission data. ing.
This transmission time is used when measuring the packet delay time in the data reception device 2E.

The round-trip delay response means 14 receives a request (echo request) transmitted from the data receiving device 2E and transmits a response (echo response) to the request to the data receiving device 2E. The echo request and the echo response are used by the data reception device 2E to measure the round trip delay time (RTT) of the packet.
As the echo request and the echo response, for example, an echo request notification and an echo response notification which are ICMP (Internet Control Message Protocol) messages defined in RFC 792 can be used.

[Configuration of data receiver]
Next, the configuration of the data reception device 2E will be described with reference to FIG. As shown in FIG. 15, the data reception device 2E includes a packet reception unit 20E, a reception rate measurement unit 21E, a reception information notification unit 22, a round-trip delay measurement unit 23, and a notification determination unit 24. . Since the reception information notification means 22 has the same configuration as that of the data reception device 2 described with reference to FIG.

  The packet receiving unit 20E basically has the same function as the packet receiving unit 20 described in FIG. 1, but further has a function of outputting the transmission time given to the packet and transmitted to the reception rate measuring unit 21E. It is added.

  The reception rate measuring unit 21E basically has the same function as the reception rate measuring unit 21 described with reference to FIG. 1, except that the packet identifier, the reception rate, and the reception side reception time are output to the notification determination unit 24. . Further, the reception rate measuring unit 21E has a function of outputting the transmission time input from the packet receiving unit 20E to the notification determining unit 24.

The round trip delay measuring means 23 measures a round trip delay time (RTT) of a packet between the data transmitting device 1E and the data receiving device 2E.
Here, the round-trip delay measuring means 23 transmits a request (echo request) for returning a response to the data transmission device 1E via the line L2, and sends a response (echo response) returned via the line L1. The RTT is measured based on the difference between the time when the echo request is received and the time when the echo response is received.
The round trip delay measuring means 23 periodically makes an echo request independently of the transmission data packet, and outputs the measured round trip delay time (RTT) to the notification determining means 24.
The round trip delay measuring means 23 measures the time when the echo request is transmitted and the time when the echo response is received by the time measuring means (not shown).

Based on the transmission time and reception side reception time input from the reception rate measurement unit 21E, the notification determination unit 24 determines the number of packets until the packet transmitted from the data transmission device 1E is received by the data reception device 2E. The one-way delay time is measured, and based on the change in the one-way delay time, it is determined whether or not to notify the data transmission apparatus 1E of reception information.
The notification determination unit 24 determines to notify the data transmission device 1E of the reception information when it is determined that the one-way delay time increases and the transition as it is exceeds a predetermined upper limit value (limit value), The packet identifier and the reception rate acquired from the reception rate measuring unit 21E are output to the reception information notification unit 22 as reception information.
Furthermore, the notification determination unit 24 determines that the notification of the reception information is necessary even when the elapsed time from the time when the reception information was last notified exceeds the rate update maximum interval time, and the reception information is determined. Output to the reception information notification means 22.

  The received information needs to be notified before the one-way delay time exceeds the upper limit value. Therefore, when the notification determination unit 24 determines that the one-way delay time exceeds the upper limit value, the round-trip delay time (measured by the round-trip delay measurement unit 23) at the transmission time that is the time when the data transmission device 1E transmits the packet ( The one-way delay time at the time when only (RTT) has elapsed is estimated, and the reception information is output to the reception information notification means 22.

That is, the notification determination unit 24 sequentially records the one-way delay time in a memory or the like, and when the one-way delay time tends to increase as shown in FIG. 16, the delay time increases at a rate from the transmission time. When it is determined that the upper limit is reached after the RTT time measured by the round trip delay measuring means 23, it is determined that the reception information needs to be notified.
Thus, the notification determination unit 24 can notify the data transmission apparatus 1E of the reception information via the reception information notification unit 22 before the one-way delay time reaches the upper limit value.

As described above, data transmitting and receiving system S _E, in the data receiving apparatus 2E, can be in consideration of the delay time of the transmission data, and notifies the timing of the update of the maximum transmission rate to a data transmission apparatus 1E.

<Operation of data transmission / reception system>
Next, FIG. 17, with reference to FIG. 18, the operation of the data transmission system S _E according to a fifth embodiment of the present invention. The maximum transmission rate update operation is the same operation as that of the data transmission / reception system S (FIG. 1), and thus the description thereof is omitted.
The measurement of the round-trip delay time (RTT) performed by the round-trip delay measuring unit 23 operates independently of the transmission packet, and thus the description thereof is omitted here.

[Packet transmission operation]
First, referring to FIG. 17 (refer to FIG. 15 as appropriate), a packet transmission operation in the data transmission device 1E will be described.
The operations in steps S1 to S3 shown in FIG. 17 are the same as those of the data transmitting apparatus 1 described in FIG.
When the temporary transmission rate calculated in step S2 is less than the maximum transmission rate determined by the maximum transmission rate determination unit 13 (Yes in step S3), the data transmission device 1E A transmission time is given to the packet input in step S1, and the packet is transmitted to the data reception device 2E via the line L1 (step S4B).
Since the subsequent operation is the same as the operation of the data transmitting apparatus 1 described with reference to FIG. 4, the same reference numerals are given and description thereof is omitted.

[Packet reception operation]
Next, referring to FIG. 18 (refer to FIG. 15 as appropriate), the packet reception operation in the data reception device 2E will be described.
First, the data reception device 2E receives a packet with a transmission time from the data transmission device 1 via the line L1 by the packet reception unit 20E (step S60).
Then, the packet receiving unit 20E outputs the received packet to the data output device B (step S61).
Further, the data reception device 2E calculates the reception rate by the reception rate measuring means 21E based on the packet length of the packet received in step S60 and the time when the packet is received (reception side reception time) (step S62).

Then, the data reception device 2E uses the notification determination unit 24 to reach the upper limit value when the one-way delay time, which is the difference between the reception side reception time and the transmission time, remains unchanged, or finally notifies the reception information. It is determined whether the elapsed time from the time has passed the rate update maximum interval time (step S63).
In step S63, when at least one of the two conditions is satisfied (Yes in step S63), the notification determination unit 24 determines that reception information notification is necessary, and the reception information notification unit 22 receives the reception information (packet identifier). , The reception rate) is transmitted (notified) to the data transmitting apparatus 1E (step 64).
At the timing when the reception information is notified, the data transmission device 1E updates the maximum transmission rate.

<< Sixth Embodiment >>
Next, with reference to FIG. 19, a description will be given of a data transmission and reception system S _F according to the sixth embodiment of the present invention.

<Outline of data transmission / reception system>
Data transmitting and receiving system S _F shown in FIG. 19, in the packet communication network, transmits the data transmission apparatus 1F is by packetizing video and audio data to a data sink 2F, video and audio data receiving apparatus 2F can receive the packet Decrypts data.
In the data transmission / reception system S shown in FIG. 1, the data transmission device 1 inputs data (packets) from the data input device A, and the data reception device 2 outputs the received packets to the data output device B. in the data transmission and reception system S _E shown in, a function of packetized encoded data to the data transmission apparatus 1F, it has a function to decode the packet based on the data to the data receiving apparatus 2F.
Hereinafter, with reference to FIG. 19, the data transmission device 1F and the data reception device 2F according to the present invention will be described in detail.

[Configuration of data transmission device]
As shown in FIG. 19, the data transmission device 1F includes a transmission rate measurement unit 10, a packet transmission unit 11F, a reception information acquisition unit 12, a maximum transmission rate determination unit 13F, and a data encoding unit 15. Yes. Since the transmission rate measuring means 10 and the received information acquiring means 12 are the same as the configuration of the data transmitting apparatus 1 described with reference to FIG. 1, the same reference numerals are given and description thereof is omitted.

  The packet transmission unit 11F basically has the same function as the packet transmission unit 11 described in FIG. However, the packet transmitting unit 11F does not consider the maximum transmission rate determined by the maximum transmission rate determining unit 13F, and transmits the packet input from the data encoding unit 15 as it is to the data receiving device 2 via the line L1. Is different.

  The maximum transmission rate determination means 13F basically has the same function as the maximum transmission rate determination means 13 described in FIG. However, the maximum transmission rate determination unit 13F is different in that the maximum transmission rate calculated by the maximum transmission rate calculation unit 13a is output to the data encoding unit 15.

Based on the maximum transmission rate determined by the maximum transmission rate determination unit 13F, the data encoding unit 15 encodes and packetizes video / audio data input from the outside so as to be equal to or less than the maximum transmission rate.
The data encoding means 15 encodes the video / audio data so that the maximum encoding rate is a rate obtained by subtracting overhead (header information such as an address) necessary for packetization from the maximum transmission rate, and the maximum encoding rate or less. Then, the header information and the like are added to packetize and output to the packet transmission means 11F.
That is, the data encoding means 15 performs encoding with a higher compression rate if the maximum encoding rate is low, and performs encoding with a lower compression rate if the maximum encoding rate is high. For this encoding, a general compression encoding method such as MPEG can be used.

[Configuration of data receiver]
Next, the configuration of the data reception device 2F will be described with reference to FIG. As shown in FIG. 19, the data reception device 2F includes a packet reception unit 20, a reception rate measurement unit 21, a reception information notification unit 22, and a data decoding unit 25. Since the configuration other than the data decoding unit 25 is the same as the configuration of the data receiving apparatus 2 described with reference to FIG. 1, the same reference numerals are given and description thereof is omitted.

  The data decoding means 25 decodes (decodes) the data (packets) received by the packet receiving means 20 into the original video / audio data. The decoding in the data decoding unit 25 can use a decoding method corresponding to the encoding of the data encoding unit 15.

As described above, data transmitting and receiving system S _F, depending on the size of the cross-traffic, the encoding rate, i.e., it is possible to change the transmission rate, even if a large cross traffic flows, bottlenecks Data transmission can be performed within the bandwidth of the link.
The operation of performing rate control in data transmission and reception system S _F is the same as the data transmitting and receiving system S described in FIG 1, the description thereof is omitted.

Although the embodiments of the present invention have been described above, these apparatuses can be operated by a program that causes a general computer to function as the above-described means.
Further, the present invention is not limited to the embodiment described here.
For example, in the data transmitting and receiving system S _C shown in FIG. 11, the update determining unit 13c is, although the round trip time (RTT) is determined whether to update the maximum transmission rate whether exceeds the upper limit, FIG Similarly to the data transmission / reception system _SD shown in FIG. 13, it may be determined whether or not to update based on the one-way delay time.

Further, in the data transmitting and receiving system S _F shown in FIG. 19, basically, by adding the data encoding means 15 in the data transmission apparatus 1 of the first embodiment shown in FIG. 1, the data decoding means to the data receiving apparatus 2 25, but in other embodiments (FIGS. 7, 11, 13, and 15), the data encoding means 15 and the data decoding means 25 may be added in the same manner. .
In that case, in the data transmission apparatus 1, the maximum transmission rate determination means 13 outputs the maximum transmission rate to the data encoding means 15, and the packet transmission means 11 transmits the packet without considering the maximum transmission rate. Should be done.

DESCRIPTION OF SYMBOLS S Data transmission / reception system 1 Data transmitter 10 Transmission rate measurement means 11 Packet transmission means 12 Reception information acquisition means 13 Maximum transmission rate determination means 13a Maximum transmission rate calculation means 13b Delay limit determination means (one-way delay limit determination means)
13c Update determination means 14 Round-trip delay response means 15 Data encoding means 2 Data reception device 20 Packet reception means 21 Reception rate measurement means 22 Reception information notification means 23 Round-trip delay measurement means 24 Notification determination means 25 Data decoding means A Data input device B Data Output device

Claims (10)

A data transmission device that transmits a packet including a packet identifier to a data reception device via a packet communication network,
A transmission rate measuring means for measuring a transmission rate of the packet, and setting a current transmission rate as a temporary transmission rate of a packet to be transmitted next;
A packet transmission means for transmitting a packet to be transmitted next to the data receiving device when the temporary transmission rate is equal to or lower than a maximum transmission rate;
From the data reception device, in association with a packet identifier included in the packet, reception information acquisition means for acquiring, as reception information, a reception rate when the packet is received;
Maximum transmission rate calculation means for calculating and updating the maximum transmission rate based on the temporary transmission rate corresponding to the packet transmitted by the packet transmission means and the reception rate corresponding to the packet and the packet identifier; Prepared,
The maximum transmission rate calculation means includes:
When the temporary transmission rate exceeds the reception rate, the bottleneck is determined from the bottleneck link bandwidth in the packet communication network based on the ratio between the temporary transmission rate and the reception rate corresponding to the packet identifier. A value obtained by subtracting the bandwidth used for cross traffic that is traffic other than the packet transmitted by the data transmission device in the link is calculated as the maximum transmission rate,
When the temporary transmission rate is equal to or lower than the reception rate, a data transmission device characterized by adding a predetermined rate increase amount to the maximum transmission rate to obtain a new maximum transmission rate. When the transmission rate is increased and the transmission rate is determined based on a round-trip delay time that is a difference between the transmission time of the packet and the reception time of the reception information corresponding to the packet and the packet identifier In addition, a delay limit determination means for calculating a limit time to reach a predetermined maximum round-trip delay time from the amount of change in the round-trip delay time,
The maximum transmission rate calculation means includes:
When the provisional transmission rate exceeds the reception rate and the delay time determination unit determines that the transmission rate has increased, the cross-traffic from the bandwidth of the bottleneck link is within the limit time. The data transmission apparatus according to claim 1, wherein the maximum transmission rate is reduced so as to be a value obtained by reducing a use band. The time when the maximum update rate is updated is held, and the round-trip delay time that is the difference between the transmission time of the packet and the reception time of the reception information corresponding to the packet and the packet identifier has reached a predetermined upper limit value. Update determination means for determining whether or not to update the maximum transmission rate depending on whether or not a predetermined elapsed time has passed since the time when the maximum update rate was updated,
The maximum transmission rate calculation means includes:
The data transmission apparatus according to claim 1, wherein the maximum transmission rate is updated when the update determination unit determines to update the maximum transmission rate. The reception information acquisition unit further acquires, from the data reception device, a reception side reception time that is a time when the packet is received in association with a packet identifier included in the packet,
When the transmission rate is increased and the transmission rate is increased and determined based on a one-way delay time that is the difference between the transmission time of the packet and the reception side reception time corresponding to the packet and the packet identifier. In addition, a one-way delay limit determination means for calculating a limit time to reach a predetermined maximum one-way delay time from the amount of change in the one-way delay time,
The maximum transmission rate calculation means includes:
When the provisional transmission rate exceeds the reception rate and the one-way delay time determination unit determines that the transmission rate has increased, the cross-band from the bottleneck link band within the limit time. 2. The data transmission apparatus according to claim 1, wherein the maximum transmission rate is reduced so as to be a value obtained by reducing a use band of traffic. The packet transmission means adds a transmission time to the packet and transmits the packet to the data receiving device,
The maximum transmission rate calculation means is a one-way difference that is a difference between a transmission time added to the packet from the data reception device and a reception side reception time of the packet in the data reception device in the reception information acquisition means. The data transmission device according to claim 1, wherein the maximum transmission rate is updated when the reception information is acquired as a notification to update the maximum transmission rate based on a change in delay time. . A data reception device that receives a packet from the data transmission device according to any one of claims 1 to 3,
Packet receiving means for receiving the packet from the data transmitting device;
A reception rate measuring means for measuring the reception rate of the packet received by the packet receiving means;
A reception information notifying means for transmitting the reception rate measured by the reception rate measuring means to the data transmitting apparatus as reception information in association with a packet identifier included in the packet;
A data receiving apparatus comprising: A data receiving device for receiving a packet from the data transmitting device according to claim 4,
A packet receiving means for receiving the packet from the data transmitting device and counting the received time as a reception time on the receiving side;
A reception rate measuring means for measuring the reception rate of the packet received by the packet receiving means;
Reception for transmitting the reception rate measured by the reception rate measuring means and the reception side reception time measured by the packet receiving means to the data transmitting apparatus as reception information in association with a packet identifier included in the packet Information notification means;
A data receiving apparatus comprising: A data receiving device for receiving a packet from the data transmitting device according to claim 5,
A packet receiving means for receiving the packet together with its transmission time from the data transmission device, and measuring the received time as a reception side reception time;
A reception rate measuring means for measuring the reception rate of the packet received by the packet receiving means;
A round trip delay measuring means for sending an echo request to the data transmitting device, receiving an echo response corresponding to the echo request and measuring a round trip delay time;
Based on the amount of change in the one-way delay time that is the difference between the transmission time and the reception side reception time, whether or not the one-way delay time reaches a predetermined upper limit after the round-trip delay time has elapsed. Notification determining means for determining whether or not notification of changing the transmission rate is necessary for the data transmission device;
When it is determined that the transmission rate needs to be changed by the notification determination unit, the reception rate measured by the reception rate measurement unit is associated with the packet identifier included in the packet as the reception information. A reception information notification means for transmitting to the transmission device;
A data receiving apparatus comprising: A data transmission device that transmits stream data as a packet including a packet identifier to a data reception device via a packet communication network,
Data encoding means for encoding and packetizing the stream data at a maximum transmission rate or less;
A transmission rate measuring means for measuring a transmission rate of the packet, and setting a current transmission rate as a temporary transmission rate of a packet to be transmitted next;
Packet transmitting means for transmitting the packet generated by the data encoding means to the data receiving device;
From the data reception device, in association with a packet identifier included in the packet, reception information acquisition means for acquiring, as reception information, a reception rate when the packet is received;
Maximum transmission rate calculation means for calculating and updating the maximum transmission rate based on the temporary transmission rate corresponding to the packet transmitted by the packet transmission means and the reception rate corresponding to the packet and the packet identifier; Prepared,
The maximum transmission rate calculation means includes:
When the temporary transmission rate exceeds the reception rate, the bottleneck is determined from the bottleneck link bandwidth in the packet communication network based on the ratio between the temporary transmission rate and the reception rate corresponding to the packet identifier. A value obtained by subtracting the bandwidth used for cross traffic that is traffic other than the packet transmitted by the data transmission device in the link is calculated as the maximum transmission rate,
When the temporary transmission rate is equal to or lower than the reception rate, a data transmission device characterized by adding a predetermined rate increase amount to the maximum transmission rate to obtain a new maximum transmission rate. A data receiving device for receiving a packet from the data transmitting device according to claim 9,
Packet receiving means for receiving the packet from the data transmitting device;
Data decoding means for decoding the packet received by the packet receiving means into stream data;
A reception rate measuring means for measuring a reception rate of a packet received by the packet receiving means;
A reception information notifying means for transmitting the reception rate measured by the reception rate measuring means to the data transmitting apparatus as reception information in association with a packet identifier included in the packet;
A data receiving apparatus comprising:

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