COMMUNICATION METHOD AND COMMUNICATION DEVICE

• US 20090073975A1
• Filed: 09/10/2008
• Published: 03/19/2009
• Est. Priority Date: 09/19/2007
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: SHIMONISHI, Hideyuki
• Granted Patent: US 8,004,989 B2
• Time in Patent Office: Days
• US Class Current: 370/389
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/11 Identifying congestion
• CPC Class Codes: H04L 47/193 at the transport layer, e.g. TCP related
• CPC Class Codes: H04L 47/25 with rate being modified by the source upon detecting a change of network conditions
• CPC Class Codes: H04L 47/27 Evaluation or update of window size, e.g. using information derived from acknowledged [ACK] packets
• CPC Class Codes: H04L 47/283 in response to processing delays, e.g. caused by jitter or round trip time [RTT]

Abstract

A communication method includes steps of: transmitting a plurality of packets to a network according to a window specifying a data amount of the packets to be transmitted to the network; receiving ACK related to the packets transmitted to the network, and detecting whether or not packet discard occurs; measuring a RTT by using the received ACK; calculating a discarding interval indicating a time interval of the packet discard; calculating an increase amount for a current window by using the calculated discarding interval; and updating the current window by using the calculated increase amount if the packet discard is not detected.

Claims

1. A communication method comprising steps of:

transmitting a plurality of packets to a network according to a window specifying a data amount of the packets to be transmitted to the network;

receiving acknowledgement (ACK) related to the packets transmitted to the network, and detecting whether or not packet discard occurs;

measuring a round trip time (RTT) by using the received ACK;

calculating a discarding interval indicating a time interval of the packet discard;

calculating an increase amount for a current window by using the calculated discarding interval; and

updating the current window by using the calculated increase amount if the packet discard is not detected.

2. The communication method according to claim 1, wherein

the step of calculating the discarding interval includes calculating an average value of the discarding interval up to current time, and

the step of calculating the increase amount includes calculating the increase amount by using a product between a parameter specifying a magnification of an increase amount for a window and a larger value either a latest value of the discarding interval or the calculated average value of the discarding interval.

3. The communication method according to claim 2,

wherein the step of calculating the increase amount includes calculating the increase amount by multiplying the product by a decrease function of the measured RTT.

4. The communication method according to claim 1, further comprising a step of determining whether or not the measured RTT is equal to or smaller than a threshold,

wherein the step of calculating the discarding interval includes calculating a conditional discarding interval which is the discarding interval while the measured RTT is equal to or smaller than the threshold, and calculating an average value of the conditional discarding interval up to current time, and

the step of calculating the increase amount includes calculating the increase amount for the current window by using a product among a parameter specifying a magnification of an increase amount for a window, an increase function of the measured RTT, and a larger value either a latest value of the conditional discarding interval or the average value of the conditional discarding interval.

5. The communication method according to claim 4, further comprising a step of calculating an expected value of a discarding interval by using the calculated discarding interval,

wherein the step of calculating the increase amount includes calculating the increase amount by multiplying the product by a term (1−

E) including a value E as the calculated expected value of a discarding interval.

6. The communication method according to claim 4, further comprising a step of calculating an expected value of a discarding interval by using the calculated discarding interval,

wherein the step of measuring the RTT includes revising the measured RTT by adding the calculated expected value of a discarding interval to the measured RTT, and

the step of calculating the increase amount includes calculating the increase amount by using the revised measured RTT.

7. The communication method according to claim 5,

wherein the step of calculating the expected value includes calculating the expected value by using a function g(x, y) having a maximum value while the x is equal to the y, where the x is the calculated average value of the conditional discarding interval and the y is the latest value of the conditional discarding interval.

8. The communication method according to claim 6,

wherein the step of calculating the expected value includes calculating the expected value by using a function g(x, y) having a maximum value while the x is equal to the y, where the x is the calculated average value of the conditional discarding interval and the y is the latest value of the conditional discarding interval.

9. The communication method according to claim 5,

wherein the step of calculating the expected value includes calculating the expected value by using a function g(x, y) having a maximum value while the x is equal to the y, where the x is the calculated average value of the discarding interval and the y is the latest value of the discarding interval.

10. The communication method according to claim 5,

wherein the step of calculating the increase amount includes calculating the increase amount for the current window by subtracting a term of the increase function of the measured RTT from a value obtained by multiplying the product by the term (1−

E).

11. The communication method according to claim 1, further comprising a step of setting a threshold for changing an increase degree of the current window,

wherein the step of updating the current window includes increasing the current window by a larger degree if the current window is smaller than the set threshold instead of being larger than it.

12. The communication method according to claim 11,

wherein the step of setting a threshold includes making the threshold currently set small if the reception unit does not detect the packet discard, and making the threshold currently set large if the reception unit detects the packet discard.

13. The communication method according to claim 1,

wherein the step of updating the current window includes calculating a decrease amount for the current window by using a congestion degree of the network based on the measured RTT, and updating the current window by using the calculated decrease amount if the reception unit detects the packet discard.

14. A communication device comprising:

a transmission unit transmitting a plurality of packets to a network according to a window specifying a data amount of the packets to be transmitted to the network;

a reception unit receiving acknowledgement (ACK) related to the packets transmitted to the network, and detecting whether or not packet discard occurs;

a RTT measurement unit measuring a round trip time (RTT) by using the received ACK;

a discard interval calculation unit calculating a discarding interval indicating a time interval of the packet discard; and

a window setting unit calculating an increase amount for a current window by using the calculated discarding interval, and updating the current window by using the calculated increase amount if the reception unit does not detect the packet discard.

15. The communication device according to claim 14, wherein

the discard interval calculation unit calculates an average value of the discarding interval up to current time whenever calculating the discarding interval, and

the window setting unit calculates the increase amount by using a product between a parameter specifying a magnification of an increase amount for a window and a larger value either a latest value of the discarding interval or the calculated average value of the discarding interval.

16. The communication device according to claim 15,

wherein the window setting unit calculates the increase amount by multiplying the product by a decrease function of the measured RTT.

17. The communication device according to claim 14, further comprising a RTT determination unit determining whether or not the measured RTT is equal to or smaller than a threshold,

wherein the discard interval calculation unit calculates a conditional discarding interval which is the discarding interval while the measured RTT is equal to or smaller than the threshold, and calculates an average value of the conditional discarding interval up to current time whenever calculating the conditional discarding interval, and

the window setting unit calculates the increase amount for the current window by using a product among a parameter specifying a magnification of an increase amount for a window, an increase function of the measured RTT, and a larger value either a latest value of the conditional discarding interval or the average value of the conditional discarding interval.

18. The communication device according to claim 17, further comprising an expected value calculation unit calculating an expected value of a discarding interval by using the calculated discarding interval,

wherein the window setting unit calculates the increase amount by multiplying the product by a term (1−

E) including a value E as the calculated expected value of a discarding interval.

19. The communication device according to claim 17, further comprising an expected value calculation unit calculating an expected value of a discarding interval by using the calculated discarding interval,

wherein the RTT measurement unit revises the measured RTT by adding the calculated expected value of a discarding interval to the measured RTT, and

the window setting unit calculates the increase amount by using the revised measured RTT.

20. The communication device according to claim 18,

wherein the expected value calculation unit calculates the expected value by using a function g(x, y) having a maximum value while the x is equal to the y, where the x is the calculated average value of the conditional discarding interval and the y is the latest value of the conditional discarding interval.

21. The communication device according to claim 19,

wherein the expected value calculation unit calculates the expected value by using a function g(x, y) having a maximum value while the x is equal to the y, where the x is the calculated average value of the conditional discarding interval and the y is the latest value of the conditional discarding interval.

22. The communication device according to claim 18,

wherein the expected value calculation unit calculates the expected value by using a function g(x, y) having a maximum value while the x is equal to the y, where the x is the calculated average value of the discarding interval and the y is the latest value of the discarding interval.

23. The communication device according to claim 18,

wherein the window setting unit calculates the increase amount for the current window by subtracting a term of the increase function of the measured RTT from a value obtained by multiplying the product by the term (1−

E).

24. The communication device according to claim 14, further comprising a threshold setting unit setting a threshold for changing an increase degree of the current window,

wherein the window setting unit increases the current window by a larger degree if the current window is smaller than the set threshold instead of being larger than it.

25. The communication device according to claim 24,

wherein the threshold setting unit makes the threshold currently set small if the reception unit does not detect the packet discard, and makes the threshold currently set large if the reception unit detects the packet discard.

26. The communication device according to claim 14,

wherein the window setting unit calculates a decrease amount for the current window by using a congestion degree of the network based on the measured RTT, and updates the current window by using the calculated decrease amount if the reception unit detects the packet discard.

27. A computer-readable medium recorded a program for causing a computer to perform as the communication device of claim 14.