JP2010206608A - Transmission apparatus, transmission rate calculation method and transmission rate calculation program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmission apparatus, transmission rate calculation method and transmission rate calculation program in which a transmission rate corresponding to a congestion state of a network can be determined even if a frequency of ACK is decreased. <P>SOLUTION: The transmission apparatus 10 is configured to perform transmission rate control by receiving an acknowledgement signal from a receiving apparatus 20 which transmits the acknowledgement signal each time M pieces of (M is an integer of ≥2) data packets are received. The transmission apparatus 10 comprises: a transmission rate change estimation section 11 for estimating a transmission rate change in the case where the acknowledgement signal is returned from the receiving apparatus 20 each time N pieces of (N is an integer smaller than M) data packets are received; and a transmission rate calculation section 12 for calculating a transmission rate based on the transmission rate change estimated by the transmission rate change estimation section 11. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a transmission apparatus, a transmission rate calculation method, and a transmission rate calculation program, and more particularly to setting of a transmission rate using an acknowledgment signal.

  TCP (Transmission Control Protocol) is an example of a protocol for performing transmission rate control while performing transmission confirmation of data packets between transmission and reception terminals. In the TCP rate control method, the transmitting terminal receives an ACK (Acknowledgement) packet from the receiving terminal. The transmitting terminal controls the amount of data packet that can be transmitted without waiting for the reception of the ACK packet. If the transmission is successful, the transmission amount is increased, and if the transmission is unsuccessful, the transmission amount is decreased.

  TCP control described in Non-Patent Document 1 will be described with reference to FIGS. FIG. 12 is a configuration diagram of the transmission terminal 100 and the reception terminal 200 that perform TCP communication.

  First, the transmission terminal 100 will be described. The data transmission unit 101 extracts data from the transmission data storage unit 104 and transmits data packets at the transmission rate notified from the transmission rate determination unit 103. When ACK receiving section 102 receives an ACK packet from receiving terminal 200 and detects a packet loss at receiving terminal 200, ACK receiving section 102 requests retransmission to data transmitting section 101. Further, it notifies the transmission rate determining unit 103 whether or not the data packet has been successfully transmitted.

  The transmission rate determining unit 103 receives the ACK packet, and when the ACK number included in the ACK packet advances and it is found that the data packet has been successfully transmitted, the transmission rate determining unit 103 increases the transmission amount. As a method of increasing, as shown in FIG. 13, when the current transmission amount is smaller than a predetermined ssthresh (slow start threshold), the transmission rate is doubled every time an ACK packet is received. When the current transmission amount is larger than ssthresh, it is increased by 1 / (current transmission rate) every time an ACK packet is received.

  Further, when ACK packets with the same ACK number are received repeatedly, it is determined that the receiving terminal 200 has lost the packet, and the transmission amount is halved. If no ACK packet is received for a certain period of time, the transmission amount is reduced to one data packet. The transmission data storage unit 104 stores data to be transmitted.

  Next, the receiving terminal 200 will be described. The data reception unit 201 receives data from the transmission terminal 100, notifies the ACK transmission unit 202 of the sequence number that has been received, and accumulates the data in the reception data accumulation unit 204. The ACK transmission unit 202 creates an ACK packet with the frequency notified from the ACK frequency determination unit 203 as an ACK number from the sequence number notified from the data reception unit 201 as an ACK number, and returns the ACK packet. The ACK frequency determination unit 203 instructs the ACK transmission unit 201 to return an ACK packet every time a data packet X (X is an integer equal to or greater than 1) is received and to return an ACK packet after a predetermined time has elapsed. In TCP, X = 2 is recommended.

M.M. Allman, V .; Paxson, W.M. Stevens, "RFC2581 TCP congestion control" IETF, April 1999

  When X that determines the frequency of ACK packets takes a large value, or when a certain period of time increases, the frequency of ACK packets decreases, the granularity of transmission rate control becomes coarse, and the transmission rate according to changes in network congestion Control becomes difficult.

  This will be specifically described with reference to FIG. FIG. 14 shows a change in rate when the frequency of ACK decreases. A circled plot represents a change in transmission rate when an ACK packet is returned every time a data packet is received, and a square mark plot represents a change in transmission rate when an ACK packet is returned every 3 data packets are received. ing. As shown in FIG. 14, when an ACK packet is returned every time three data packets are received, there is a problem that the timing of rate reduction is delayed in response to network congestion, and a problem that the increase in transmission rate is slowed down. is there.

  The present invention has been made to solve such problems, and a transmission apparatus and a transmission rate calculation method capable of determining a transmission rate according to a congestion state of a network even if the frequency of ACKs is reduced. An object of the present invention is to provide a transmission rate calculation program.

  The transmitting apparatus according to the first aspect of the present invention receives the acknowledgment signal from a receiving apparatus that transmits the acknowledgment signal every time M (M is an integer of 2 or more) data packets are received, and performs transmission rate control. A transmission apparatus that performs transmission, and estimates a change in transmission rate when the acknowledgment signal is returned for each reception of N (N is an integer smaller than M) data packets when the acknowledgment signal is received. And a transmission rate calculation unit that calculates a transmission rate based on the transmission rate change estimated by the transmission rate change estimation unit.

  The transmission rate calculation method according to the second aspect of the present invention is a transmission rate calculation based on an acknowledgment signal generated every time M (M is an integer of 2 or more) data packets are received. A rate calculation method, wherein when the acknowledgment signal is generated every N data packets (N is an integer smaller than M), a transmission rate change is estimated based on the acknowledgment signal; Calculating a transmission rate based on the estimated transmission rate change.

  The transmission rate calculation program according to the third aspect of the present invention is a transmission that calculates a transmission rate based on an acknowledgment signal generated every time M (M is an integer of 2 or more) data packets are received. A rate calculation program for estimating a change in transmission rate based on the acknowledgment signal when the acknowledgment signal is generated every N (N is an integer smaller than M) data packets; The step of calculating a transmission rate based on the estimated transmission rate change is executed by a control computer of the transmission apparatus.

  According to the present invention, it is possible to provide a transmission apparatus, a transmission rate calculation method, and a transmission rate calculation program that can determine a transmission rate according to the congestion state of the network even if the frequency of ACKs decreases.

1 is a configuration diagram of a transmission device according to a first exemplary embodiment; 1 is a configuration diagram of a transmission device and a reception device according to a first embodiment. FIG. 3 is a diagram illustrating a packet loss detection method according to the first exemplary embodiment. FIG. 3 is a configuration diagram of an ACK packet according to the first embodiment. FIG. 6 is a diagram showing a change in transmission rate according to the first exemplary embodiment. 4 is a flowchart of a transmission device and a reception device according to the first exemplary embodiment. FIG. 6 is a diagram illustrating transmission rate change control according to the first exemplary embodiment; FIG. 3 is a configuration diagram of a transmission device and a reception device according to a second exemplary embodiment. It is a figure which shows the transmission rate change concerning Embodiment 2. FIG. It is a figure which shows the transmission rate change concerning Embodiment 2. FIG. 6 is a flowchart of a transmission device and a reception device according to a second exemplary embodiment. It is a block diagram of the conventional transmitter and receiver. It is a figure which shows the conventional transmission rate change. It is a figure which shows the conventional transmission rate change.

(Embodiment 1)
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a transmission apparatus according to Embodiment 1 of the present invention. Here, the transmitting device 10 receives an acknowledgment signal (ACK packet) from the receiving device 20 in order to confirm the delivery result of the data packet transmitted to the receiving device 20. The reception device 20 transmits an acknowledgment signal to the transmission device 10 every time M data packets (M is an integer of 2 or more) are received. The transmission device 10 performs transmission rate control based on the received acknowledgment signal. The transmission device 10 includes a transmission rate change estimation unit 11 and a transmission rate calculation unit 12.

  When the transmission rate change estimation unit 11 receives an acknowledgment signal from the receiving device 20, the acknowledgment signal is returned every time N data packets (N is an integer smaller than M) are received from the receiving device 20. Estimate the change in transmission rate. Specifically, the transmission rate is increased when the reception device 20 has successfully received the data packet, and the transmission rate is decreased when the reception device 20 has failed to receive the data packet. Estimate changes. Information regarding whether or not the reception device 20 has successfully received the data packet can be confirmed based on a confirmation signal received by the transmission device 10 from the reception device 20.

  The transmission rate calculation unit 12 calculates the transmission rate based on the transmission rate change estimated by the transmission rate change estimation unit 11.

  Next, the configuration of the transmission apparatus and the reception apparatus according to the first embodiment of the present invention will be described in detail with reference to FIG. The transmitting device 10 transmits a data packet including a sequence number that uniquely identifies the packet, and the receiving device 20 uses the TCP SACK (Selective ACK) option to set a sequence number that is expected to be received next as an ACK number. The ACK packet including the sequence number of the received data packet is returned to the transmitting apparatus 10.

  The transmission device 10 includes a transmission rate change estimation unit 11, a transmission rate calculation unit 12, a data transmission unit 13, an ACK reception unit 14, an RTT (Round Trip Time) measurement unit 15, and a transmission data storage unit 16. ing.

  The data transmission unit 13 acquires data from the transmission data storage unit 16 and packetizes the acquired data. Then, the packet is transmitted according to the transmission rate notified from the transmission rate calculation unit 12. In addition, when the data packet is transmitted, the RTT measuring unit 15 is notified of the transmission time.

  The ACK receiver 14 notifies the RTT measuring unit 15 of the reception time when receiving the ACK packet. Furthermore, when occurrence of packet loss is detected from information included in the received ACK packet, the data transmission unit 13 is instructed to retransmit the packet lost. The packet loss is determined when a certain number or more of ACK packets having the same ACK number are received or when no ACK packet is received for a certain time. A method for detecting occurrence of packet loss will be described in detail later. Further, the ACK receiving unit 14 notifies the transmission rate change estimating unit 11 of the ACK packet.

  The RTT measurement unit 15 obtains the data packet transmission time from the data transmission unit 13 and the ACK packet reception time from the ACK reception unit 14. As a result, an RTT value indicating the time from when a data packet is transmitted to when an ACK for the data packet is received is calculated. The transmission rate change estimation unit 11 is notified of the RTT value thus obtained.

  The transmission rate change estimation unit 11 acquires information on whether or not the reception device 20 has normally received the data packet from the ACK packet notified from the ACK reception unit 14. Further, based on the RTT value acquired from the RTT measurement unit 15, the receiving device 20 estimates a change in the transmission rate that changes when an ACK packet is returned every time a data packet is received. The estimation result is notified to the transmission rate calculation unit 12.

  Next, a method for estimating a change in transmission rate will be described with reference to FIGS. The receiving device 20 returns an ACK packet each time it receives a data packet, and estimates a change in transmission rate when the transmitting device 10 receives the ACK packet.

  FIG. 3 shows how data packets and ACK packets are transmitted. The transmitting apparatus 10 transmits data packets with sequence numbers 100 to 2400 with a data packet size of 100 bytes (solid line arrows). For example, the data packet 100 transmitted from the transmission device 10 is composed of data with sequence numbers 100 to 199. FIG. 3 shows that data packets 600, 700, 800, 1900 are lost.

  The receiving device 20 receives 20 data packets from the transmitting device 10 and returns the ACK packet shown in FIG. 4 to the transmitting device 10 (solid line arrow from the receiving device 20 to the transmitting device 10 in FIG. 3). Specifically, when the data packet 2400 is acquired, since 20 data packets are reached, an ACK packet is returned. Since the latest sequence number that the receiving device 20 can continuously receive is up to 599, the ACK number of the ACK packet is set to 600. Further, 900 to 1899 and 2000 to 2499 are included as sequence numbers of data packets that can be received.

  When the transmission rate change estimation unit 11 receives the ACK packet from the ACK reception unit 14, the transmission rate change estimation unit 11 acquires the current transmission rate from the transmission rate calculation unit 12 and acquires the RTT value from the RTT measurement unit 15. Further, the transmission rate when an ACK is returned every time a data packet is received is estimated from the sequence number indicated in the ACK packet. FIG. 5 shows changes in the transmission rate when the receiving apparatus 20 returns an ACK every time it receives one data packet. As shown in FIG. 5, the transmission rate at the time of receiving the ACK packet is rate_a, which is larger than the transmission rate threshold. Since it can be seen that five data packets with sequence numbers 100 to 599 from the ACK packet shown in FIG. 4 have been successfully transmitted, the transmission rate is increased by a fixed amount five times from the transmission rate rate_a in FIG. The transmission rate control of the transmission apparatus 10 increases the transmission rate if the data transmission is successful, and decreases the transmission rate if the data transmission fails.

  The transmission rate is increased by setting a threshold for the transmission rate, and if it is equal to or less than the threshold, the transmission data rate is doubled, for example, every time an ACK packet for which data transmission has been successful is received, and exponentially increased. When the transmission rate is equal to or higher than the threshold value, the transmission rate is increased by a certain amount every time an ACK packet having been successfully transmitted is received, and is increased linearly.

  Here, the packet loss detection method and rate control of the receiving device 20 in the transmitting device 10 will be described. When the receiving device 20 returns an ACK packet every time a data packet is received, the packet loss detection method is (1) when a plurality of ACK packets with the same ACK number are received (2) when an ACK packet is not received for a certain period of time (retransmission timeout) Detection). In the case of (1), the transmission rate control halves the transmission rate immediately before the packet loss detection, and in the case of (2), the transmission rate is reduced to a rate at which at least one data packet can be transmitted before the next ACK is received. The retransmission timeout time is obtained by RTT + 4 × (average deviation of RTT). Here, if it is determined that three ACK packets having the same ACK number have been received and lost, the transmitting apparatus 10 receives the ACK packet having the ACK number 600 three times consecutively when receiving the ACK packet (7) in FIG. Will do. As a result, it is detected that a data packet with the sequence number 600 has been lost, and the data packet transmission with the sequence number 1300 is interrupted to perform retransmission. The transmission rate is increased by a certain amount every time an ACK packet is received until data transmission of this retransmission packet is successful (section A in FIG. 5). Successful retransmission of the data packet with the sequence number 600 is detected by the reception of the ACK packet (10) in FIG. At this time, the transmission rate is halved (timing B in FIG. 5). At this time, the transmission rate threshold value is updated to a transmission rate value halved.

  Next, when the ACK packet (12) in FIG. 3 is received, the ACK packet with the ACK number 700 is received three times in succession. As a result, it is detected that a loss of the data packet with the sequence number 700 has occurred, and the retransmission is performed by interrupting the data transmission with the sequence number 1800. Until the reception of the ACK packet of (14) in FIG. 3, the transmission rate is increased by a certain amount every time the ACK packet is received (section C in FIG. 5). By receiving the ACK packet of (15) in FIG. 3, it is detected that the retransmission of sequence number 700 is successful, and the transmission rate of sequence number 2200 is halved (timing D in FIG. 5). At this time, the transmission rate threshold value is updated to a half of the transmission rate threshold value.

  Next, it is assumed that the retransmission timeout occurred because the 800th ACK packet was not received for a certain period of time immediately before the data packet having the sequence number 2200 was transmitted. At this time, the transmission rate is reduced to a transmission rate at which at least one data packet can be transmitted until the next ACK packet is received (timing E in FIG. 5). Thereafter, the transmission rate is increased until the ACK packet (19) in FIG. 3 is received. Since the transmission rate is smaller than the transmission rate threshold, the transmission rate is doubled every time an ACK packet is received (section F in FIG. 5).

  As described above, from the information of the ACK packet and the RTT, when the data packet transmission is successful, it is determined whether or not it is larger than the transmission rate threshold value, and the increase rate of the transmission rate is estimated. In the case of a data packet loss, it is judged from the RTT whether or not a retransmission timeout occurs, and the reduction width is estimated. The transmission rate calculation unit 12 is notified of the estimation result of the transmission rate change thus estimated.

  By estimating the change in transmission rate when an ACK packet is returned for each data packet, the transmission apparatus 10 does not simply increase or decrease the rate, but instead of the data packet transmission success and failure to the network congestion situation. It is possible to control the rate accordingly. That is, it is possible to realize rate control with fine control granularity despite the low frequency of ACK packets.

  The transmission rate calculation unit 12 acquires transmission rate change estimation information from the transmission rate change estimation unit 11. From the estimated change in the transmission rate, it is possible to calculate the transmission data amount from when the transmission device 10 transmits the data packet to when the ACK packet is received when the ACK packet is returned for each data packet. The amount of transmission data calculated in this way is estimated as the amount of transmission data that can be transmitted before the arrival of the next ACK packet. The transmission rate is set so that this transmission data amount can be transmitted before the next ACK packet arrives. The set rate is notified to the data transmission unit 13.

  The transmission rate may be the average transmission rate of the transmission rate estimated by the transmission rate change estimation unit 11, and the average of the transmission rates immediately before the loss is calculated as an index value that uses up the network bandwidth. Also good. The transmission rate immediately before the loss is the transmission rate when circled in FIG.

  The transmission data storage unit 16 stores data to be transmitted.

  As described above, the transmission apparatus 10 has been described with the control of increasing the transmission rate when the data packet transmission is successful and decreasing the transmission rate when the data packet fails, but in addition to the above, the transmission apparatus 10 controls the transmission rate using the ACK packet as a trigger. It can also be applied to existing methods. In the above description, the processing in the transmission device 10 has been described. However, the reception device 20 that has received the data packet can perform the same processing as the transmission device 10 based on the information of the generated ACK packet. It is.

  Next, the configuration of the receiving device 20 in FIG. 2 will be described. The reception device 20 includes a data reception unit 21, an ACK transmission unit 22, an ACK frequency determination unit 23, and a reception data storage unit 24.

  The data reception unit 21 receives a data packet from the transmission device 10. The data reception unit 21 notifies the ACK transmission unit 22 of information on the received data. Specifically, it is the sequence number of the data packet. Further, the data receiving unit 21 stores the data packet in the received data storage unit 24.

  As illustrated in FIG. 4, the ACK transmission unit 22 creates an ACK packet including a sequence number that uniquely identifies the received data packet, and transmits the ACK packet to the transmission device 10 according to the frequency notified from the ACK frequency degree determination unit 23. Send.

  The ACK frequency determination unit 23 determines the frequency of transmitting ACK to the transmission device 10 and notifies the ACK transmission unit 22 of the frequency. The frequency of ACK described above is that an ACK packet is returned to the transmission apparatus 10 every time data packet X (X is an integer of 1 or more) is received, or an ACK packet is returned periodically. To the ACK transmission unit 22, the value of X or the time for periodically returning the ACK packet is determined and notified to the ACK transmission unit 22.

  Next, the processing flow of the transmitting apparatus and the receiving apparatus according to the first embodiment of the present invention will be described with reference to FIG.

  First, the transmission apparatus 10 extracts data from the transmission data storage unit 16 and packetizes it. Further, the data packet is transmitted according to the transmission rate notified from the transmission rate calculation unit 12. At this time, the packet size is 100 bytes. The data packet includes a sequence number that uniquely identifies the data packet (S100).

  Next, in the receiving device 20, the ACK frequency determining unit 23 is notified to generate and send an ACK packet every time 20 data packets are received. As shown in FIG. 3, the receiving device 20 creates and returns an ACK packet when receiving the data packet with the sequence number 2400, and the transmitting device 10 receives the ACK packet (S101).

  Next, the ACK receiving unit 14 notifies the transmission rate change estimating unit 11 of ACK packet information including an ACK number, a sequence number of received data, and the like. In addition, the ACK receiver 14 instructs the data transmitter 13 to retransmit the lost packet. The RTT measurement unit 15 calculates the RTT and notifies the transmission rate change estimation unit 11 of the RTT (S102).

  Next, the transmission rate change estimation unit 11 estimates a change in the transmission rate and notifies the transmission rate calculation unit 12 (S103). The method for estimating the transmission rate change is the same as that described with reference to FIGS.

  Next, the transmission rate calculation unit 12 calculates the transmission rate from the transmission rate change notified from the transmission rate change estimation unit 11 and the transmission data amount to be transmitted until the next reception of the ACK packet (S104), The data transmission unit 13 is notified (S105).

  Next, a flow of transmission rate change estimation processing according to the first exemplary embodiment of the present invention will be described with reference to FIG. The ACK receiving unit 14 checks whether there is a data packet loss in the receiving device 20 after receiving the ACK packet (S200). If there is a data packet loss, it is checked whether a retransmission timeout occurs (S201). If a retransmission timeout occurs, the transmission rate is minimized (S202). If retransmission timeout does not occur, the transmission rate is halved (S203).

  Next, in S200, if there is no loss, it is confirmed whether the present transmission rate is larger than a transmission rate threshold value (S204). If it is larger than the threshold, the transmission rate is increased by a certain amount (S205). If it is smaller than the threshold, the transmission rate is doubled, for example (S206).

  As described above, by using the transmission apparatus according to the first embodiment of the present invention, even if the frequency of ACK decreases, the change in transmission rate when ACK is returned for each data packet, for example. By estimating and determining the transmission rate, transmission rate control according to the congestion state of the network can be realized. That is, by reducing the frequency of ACK, it is possible to reduce the number of ACK packets sent to the network, and the processing load associated with the ACK packet processing of the transmission device and the reception device can be reduced. Furthermore, highly accurate transmission rate control can be performed as in the case where an ACK packet is returned for each data packet, for example.

(Embodiment 2)
The configuration of the transmission apparatus 10 according to the second embodiment of the present invention will be described with reference to FIG. The transmission apparatus 10 has a configuration in which a transmission rate change control unit 17 is added to the configuration of the transmission apparatus 10 of FIG. Other configurations are the same as those in FIG.

  The transmission rate change control unit 17 acquires the transmission rate from the transmission rate calculation unit 12. In addition, the reception time of the ACK packet and the number of data packets to be sent before the arrival of the ACK packet can be acquired from the ACK reception unit 14, and the number of data packets acquired from the ACK reception unit 14 can be transmitted until the next ACK packet is received. Thus, the arrival transmission rate, the increase / decrease of the transmission rate, and the timing are determined. The arrival transmission rate is a transmission rate set when the next ACK packet is received. When the transmission rate is a certain value or more than the value of the current transmission rate, if the transmission rate is rapidly increased, congestion may occur in the network, so that the transmission rate is increased linearly. Here, the increase / decrease of the transmission rate and the timing control method will be described separately in two cases.

  (1) In the case of current transmission rate + α ≦ transmission rate calculated by the transmission rate calculation unit 12. α represents an arbitrary transmission rate value.

  As described above, in this case, the transmission rate increases rapidly, and congestion may occur in the network. For this reason, the transmission rate is increased linearly to suppress congestion due to a rapid rate increase. First, the increase timing will be described. The timing for increasing the transmission rate is matched with the transmission rate control timing when the receiving device 20 returns an ACK packet every time one data packet is received. The number is increased at the same number of times as the number of data packets transmitted until the ACK packet is received. FIG. 9 shows a state in which four data packets are transmitted until an ACK packet is received. Therefore, the increase timing is a value obtained by dividing the ACK packet arrival interval calculated from the time notified from the ACK receiver 14 by 4. In FIG. 9, the value is T.

  Next, the transmission rate reached by increasing the transmission rate four times will be described. Until the next ACK packet arrives, the data packet amount (area of the shaded area in FIG. 11) transmitted at the transmission rate rate_c notified from the transmission rate calculation unit 12 is transmitted. The transmission rate to reach is 2 × rate_c-rate_a. Therefore, the transmission rate increase amount β at one time is β = 2 (rate_c−rat_a) / 4. FIG. 9 shows that the current transmission rate rate_a + α is smaller than the rate_c calculated by the transmission rate calculation unit 12. As described above, 2 (rate_c-rat_a) / 4 transmission rate is increased every T time. This information is notified to the data transmission unit 13.

  (2) When the transmission rate calculated by the transmission rate calculation unit 12 <the current transmission rate + α. α represents an arbitrary transmission rate value.

  In this case, even if the current transmission rate is changed to the transmission rate calculated by the transmission rate calculation unit 12, it is unlikely that congestion will occur in the network, so transmission is performed at the transmission rate rate_c as shown in FIG. Thus, the data transmission unit 13 is notified.

  Next, with reference to FIG. 11, the processing flow of the transmitting apparatus and the receiving apparatus according to the second embodiment of the present invention will be described. The process up to S304 is the same as that up to S104 in FIG.

  The transmission rate calculation unit 12 calculates the transmission rate from the transmission rate change notified from the transmission rate change estimation unit 11 and the transmission data amount to be transmitted until the next ACK packet is received, and sends it to the transmission rate change control unit 17. Output. The transmission rate change estimation unit 11 obtains the transmission rate, the ACK reception unit 14 obtains the ACK packet reception time and the number of data packets transmitted until the arrival of the ACK packet, and obtains the increase amount and timing of the transmission rate as described above (S205). ), And notifies the data transmitter 13 (S206).

  As described above, by using the transmission apparatus according to the second embodiment of the present invention, when the calculated transmission rate is larger than the current transmission rate, the transmission rate is not increased suddenly but linearly. By gradually increasing the network congestion, network congestion can be avoided.

  The above description describes the embodiment of the present invention, and the present invention is not limited to the above embodiment. Moreover, those skilled in the art can easily change, add, and convert each element of the above embodiments within the scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Transmission apparatus 11 Transmission rate change estimation part 12 Transmission rate calculation part 13 Data transmission part 14 ACK reception part 15 RTT measurement part 16 Transmission data storage part 17 Transmission rate change control part 20 Reception apparatus 21 Data reception part 22 ACK transmission part 23 ACK Frequency determination unit 24 Received data storage unit

Claims (17)

A transmission apparatus that receives the confirmation response signal from a reception apparatus that transmits an acknowledgment signal every time M data packets are received (M is an integer of 2 or more), and performs transmission rate control;
A transmission rate change estimator for estimating a change in transmission rate when the acknowledgment signal is returned every N (N is an integer smaller than M) data packets received from the receiving device when receiving the acknowledgment signal; ,
A transmission apparatus comprising: a transmission rate calculation unit that calculates a transmission rate based on a transmission rate change estimated by the transmission rate change estimation unit.   The transmission rate calculation unit calculates an amount of data packets that can be transmitted from the change in the transmission rate until a next acknowledgment signal is received, and calculates a transmission rate according to the amount of data packets. 1. The transmission device according to 1.   A transmission rate change control unit that determines the amount of increase / decrease of the transmission rate to be set next and the change timing of the current transmission rate based on the magnitude relationship between the current transmission rate and the transmission rate calculated by the transmission rate calculation unit; The transmission device according to claim 1, further comprising:   The transmission rate change estimation unit includes the current transmission rate, a predetermined transmission rate threshold, a timing until receiving an acknowledgment signal after transmitting the data packet, and a successful reception of the data packet included in the acknowledgment signal. Alternatively, the transmission rate change in the case where the receiving apparatus sends back an acknowledgment signal every time N data packets are received is estimated based on failure information. The transmitter according to the item.   The transmission apparatus according to any one of claims 1 to 4, wherein the transmission rate change estimation unit estimates that a transmission rate increases when the reception apparatus successfully receives the data packet. .   The transmission rate change estimation unit compares the transmission rate with the transmission rate threshold when the transmission rate is estimated to increase, and increases linearly when the estimated transmission rate is equal to or higher than the transmission rate threshold. 6. The transmission apparatus according to claim 1, wherein when the transmission rate being estimated is smaller than the transmission rate threshold, the transmission rate is estimated to increase exponentially. .   The transmission apparatus according to any one of claims 1 to 4, wherein the transmission rate change estimation unit estimates that a transmission rate decreases when the reception apparatus fails to receive the data packet. .   5. The transmission rate change estimation unit, when estimating that the transmission rate is decreased, estimates that the transmission rate threshold is also decreased based on the decrease in the transmission rate. 8. The transmission device according to any one of items 7.   When the transmission rate change estimation unit determines that the transmission rate is decreased, the transmission rate change estimation unit estimates a retransmission timeout value based on a timing until receiving an acknowledgment signal after transmitting the data packet, and the retransmission timeout must occur. The transmission rate is estimated to be halved, and if the retransmission timeout occurs, the transmission rate is estimated to be a minimum value. The transmission device according to claim 1.   The transmission according to any one of claims 1 to 4, wherein the transmission rate calculation unit calculates an average value of the estimated transmission rates from the estimation of the transmission rate change, and calculates a transmission rate. apparatus.   5. The transmission rate calculation unit, wherein the transmission rate is an average of the estimated transmission rate values immediately before the transmission rate estimated from the estimation of the transmission rate change is reduced. The transmission device according to any one of 10.   The transmission rate change control unit increases the transmission rate when the transmission rate notified from the transmission rate calculation unit is greater than the current transmission rate and the difference between the transmission rate and the current transmission rate is equal to or greater than a certain value. 4. The transmission apparatus according to claim 3, wherein an amount and the transmission rate change timing are determined.   The transmission rate change control unit determines the transmission rate change timing based on an estimated timing from when the receiving apparatus returns an acknowledgment signal to when the next acknowledgment signal is returned. The transmission device according to claim 3 or 12.   When the transmission rate notified from the transmission rate calculation unit is greater than the current transmission rate and the difference between the transmission rate and the current transmission rate is greater than or equal to a certain value, the transmission rate change control unit The arrival transmission rate at which the next acknowledgment signal arrives is determined based on the number of data packets that can be transmitted at the transmission rate notified from the transmission rate calculation unit until the signal arrives. The transmission device according to claim 3 or claim 12 or claim 13.   The transmission apparatus according to claim 14, wherein the transmission rate change control unit determines a transmission rate increase amount from the transmission rate change timing and the arrival transmission rate. A transmission rate calculation method for calculating a transmission rate based on an acknowledgment signal generated every time M data packets are received (M is an integer of 2 or more),
Estimating the transmission rate change based on the acknowledgment signal when the acknowledgment signal is generated for each reception of N (N is an integer smaller than M) data packets;
A transmission rate calculation method comprising a step of calculating a transmission rate based on the estimated transmission rate change. A transmission rate calculation program for calculating a transmission rate based on an acknowledgment signal generated every time M data packets are received (M is an integer of 2 or more),
Estimating the transmission rate change based on the acknowledgment signal when the acknowledgment signal is generated for each reception of N (N is an integer smaller than M) data packets;
A transmission rate calculation program for causing a control computer of a transmission apparatus to execute a step of calculating a transmission rate based on the estimated transmission rate change.

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