JP2015185944A - Increase point determination device, communication device, increase point determination method, and computer program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve accuracy in determination of an increase point used in measurement of an available band between communication devices in a communication network.SOLUTION: An increase point determination unit 22 determines an increase point of queueing delay used in measurement of an available band between communication devices in a communication network performed while increasing a transmission rate of a test packet. The increase point determination unit 22 comprises: a first approximation processing unit 221 that approximates queueing delay until a graph division point in a graph representing queueing delay of the test packet by a first function; a second approximation processing unit 222 that approximates queueing delay after the graph division point by a second function; and a determination unit 223 that makes a graph division point where an approximation result has the least residual error an increase point.

Description

  The present invention relates to an increase point determination device, a communication device, an increase point determination method, and a computer program.

  In recent years, the available bandwidth has become an important indicator for various communication applications in the use of the Internet. For example, in video streaming, by monitoring the available bandwidth between communication terminals, the video data codec and transmission bit rate are dynamically controlled according to the available bandwidth, and video distribution suitable for the situation of the communication network is performed. Can do.

  As a technique for measuring the end-to-end usable bandwidth of a communication network, for example, a test packet (UDP (User Datagram Protocol) packet) is transmitted in the communication network, and a variation in delay experienced by the test packet, etc. There is an active measurement method that monitors (equivalent to a queuing delay) and estimates the available bandwidth based on the monitoring result. The pathChirp method is known as an example of a typical active measurement method (for example, refer nonpatent literature 1).

  In the Pathchirp method, a continuous test packet group (hereinafter referred to as a packet train) is adjusted from the transmitting terminal so that the transmission interval of the test packet decreases exponentially and transmitted to the receiving terminal (the test packet). The transmission rate increases gradually). Then, the available bandwidth is estimated by analyzing the increasing tendency of the queuing delay of each test packet calculated on the receiving terminal side. Specifically, it uses the characteristic that the queuing delay of the test packet increases when the transmission rate of the test packet exceeds the usable bandwidth, and the point at which the increase of the queuing delay starts (hereinafter referred to as an increase point). ) Is used to estimate the available bandwidth based on the transmission rate of the test packet corresponding to the increase point.

In the Pathchirp method, an increase point is determined according to the following determination condition.
[Criteria for Pathchirp method]
The “i + 1” th and subsequent queuing delays are greater than “1 / d” times the maximum value of the “i + 1” th and subsequent queuing delays. However, d is a constant larger than 1, and is set in advance. In the Pathchirp method, “d = 1.5” is used as a default value.
According to this determination condition, it is determined that the increasing tendency of the queuing delay is not continued at the point where the queuing delay decreases to “1 / d” times or less of the maximum value.

  As an available bandwidth measurement technique other than the above-mentioned Pathchirp method, Pathload is a method to narrow down the available bandwidth by dynamically adjusting the transmission rate (transmission interval) of the next test packet to be transmitted based on the observed packet delay trend. Methods (for example, see Non-Patent Document 2) and IGI methods (for example, see Non-Patent Document 3) are known. Also, a method is known in which the test packet transmission rate is adjusted by changing the packet size instead of the test packet transmission interval, or by changing both the test packet transmission interval and the packet size ( For example, refer nonpatent literature 4).

Vinay J. Ribeiro, Rudolf H. Riedi, Richard G. Baraniuk, Jiri Navratil, Les Cottrell, “pathChirp: Efficient Available Bandwidth Estimation for Network Paths”, 2003 M.Jain and C.Dovrolis, “Pathload: A measurement tool for end-to-end probing and available bandwidth”, Proceedings of Passive and Active Measurement (PAM) Workshop N. Hu and P. Steenkiste, “Evaluation and Characterization of Available Bandwidth Probing Techniques”, IEEE Journal on Selected Areas in Communications, August 2003 Koseki, Kato, Kohara, “Measurement of Internet Available Bandwidth Using Variable-length Chirp Method”, Tohoku Branch, The Society of Instrument and Control Engineers, 264th meeting, March 2011

  However, when the increase point is determined using the above-described conventional Pathchirp method determination conditions, the position of the increase point may vary greatly depending on the value of the constant d. FIG. 9 is a graph for explaining an increase point determination method using the determination conditions of the conventional Pathchirp method. In FIG. 9, when the queuing delay becomes equal to or less than the threshold value Th, the point is determined as an increase point. The threshold Th is determined based on the value of the constant d. Therefore, if the value of the constant d changes, the threshold value Th also changes, so that the increase point may also change. Further, it is difficult for the user to set the constant d to an appropriate value in an actual communication network. For this reason, it is difficult to accurately determine the increase point, and there is a possibility that the estimation accuracy of the available bandwidth is lowered. Similarly, in the above-described methods other than the Pathchirp method, a method for accurately determining an increase point is also a problem.

  The present invention has been made in consideration of such circumstances, and an increase point determination device capable of improving the accuracy of determination of an increase point used in measurement of an available bandwidth between communication devices of a communication network. It is an object to provide a communication device, an increase point determination method, and a computer program.

(1) An increase point determination device according to the present invention is an increase point for determining an increase point of a queuing delay used in measurement of an available bandwidth between communication devices of a communication network performed while increasing a transmission rate of a test packet. A determination device, a first approximation processing unit for approximating a queuing delay to a graph division point of a graph representing a queuing delay of the test packet by a first function; and a queuing delay after the graph division point A second approximation processing unit that approximates with a function of 2 and a determination unit that uses the graph division point that is an approximation result with the least residual as an increase point.
(2) The increase point determination device according to the present invention is the increase point determination device according to (1) above, with respect to the graph division point or a predetermined range in the vicinity of the graph division point including the graph division point. The increase point determination apparatus according to claim 1, wherein the approximation is performed by performing weighting that is larger than the range.
(3) The increase point determination device according to the present invention is the increase point determination device according to any one of the above (1) and (2), wherein the first function is a straight line and the second function is a straight line or a curve. It is characterized by being.
(4) The increase point determination device according to the present invention is the increase point determination device according to any one of (1) to (3) above, wherein a wireless section is included between communication devices that are targets of measurement of the usable bandwidth. Further, the first function and the second function are obtained by assigning a weight to data having a smaller queuing delay value than data having a large queuing delay value.

(5) A communication device according to the present invention receives each test packet transmitted at an increasing transmission rate, acquires a queuing delay of each test packet, and a queue for each acquired test packet The increase point determination apparatus according to any one of the above (1) to (4) that determines an increase point based on an ingress delay, and the transmission rate of a test packet corresponding to the increase point of the determination result is an available bandwidth estimation value. And an available bandwidth estimation unit.

(6) The increase point determination method according to the present invention is an increase point for determining an increase point of a queuing delay used in measurement of an available bandwidth between communication devices of a communication network performed while increasing a transmission rate of a test packet. An increase point determination method of a determination device, wherein the increase point determination device approximates a queuing delay to a graph division point of a graph representing a queuing delay of the test packet by a first function; A second approximation processing step in which the increase point determination device approximates a queuing delay after the graph division point with a second function, and the increase point determination device has an approximation result with the least residual. And a determination step using the graph division point as an increase point.

(7) The computer program according to the present invention is an increase point determination device that determines an increase point of a queuing delay used in measurement of an available bandwidth between communication devices of a communication network performed while increasing a transmission rate of a test packet. A first approximation processing step of approximating a queuing delay up to a graph division point of the graph representing the queuing delay of the test packet by a first function; and a second queuing delay after the graph division point. A computer program for executing a second approximation processing step that approximates with a function of and a determination step that uses the graph division point that is the result of approximation with the least residual as an increase point.

  According to the present invention, it is possible to improve the accuracy of determining an increase point used in measurement of an available bandwidth between communication devices of a communication network.

1 is a conceptual diagram of an available bandwidth measurement system 1 according to an embodiment of the present invention. It is a graph for demonstrating the usable bandwidth measuring method which concerns on one Embodiment of this invention. It is a graph for demonstrating the increase point determination method which concerns on one Embodiment of this invention. It is a block diagram which shows the structural example of the receiving terminal 20 shown in FIG. It is a block diagram which shows the structural example of the increase point determination part 22 shown in FIG. It is a flowchart which shows the procedure of the increase point determination process which concerns on one Embodiment of this invention. It is a graph for demonstrating the approximation process which concerns on one Embodiment of this invention. It is a graph for demonstrating the approximation process which concerns on one Embodiment of this invention. It is a graph for demonstrating the increase point determination method using the determination conditions of the conventional Pathchirp method.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a conceptual diagram of an available bandwidth measurement system 1 according to an embodiment of the present invention. In FIG. 1, the usable bandwidth measurement system 1 includes a transmission terminal 10 and a reception terminal 20. The transmitting terminal 10 transmits the packet train to the receiving terminal 20. The transmission interval of test packets in the packet train gradually decreases (in other words, the transmission rate gradually increases). The receiving terminal 20 receives the packet train, analyzes the increasing tendency of the queuing delay of each test packet in the packet train, determines the increase point, and estimates the available bandwidth.

  FIG. 2 is a graph for explaining the available bandwidth measuring method according to the present embodiment. In FIG. 2, the horizontal axis indicates the test packet number, and the vertical axis indicates the queuing delay (seconds) of the test packet. The transmission rate of test packets in the packet train gradually increases. The transmission rate of the test packet corresponding to the point (increase point) at which an increase in the queuing delay of the test packet starts is estimated as an available bandwidth. For this reason, accurately detecting the increase point leads to an improvement in the measurement accuracy of the usable bandwidth.

  FIG. 3 is a graph for explaining the increase point determination method according to the present embodiment. In FIG. 3, the horizontal axis indicates the test packet number, and the vertical axis indicates the queuing delay (seconds) of the test packet. The queuing delay is generally constant until the increase point, and starts increasing at the increase point. Therefore, the graph of the queuing delay is divided into a graph that represents the queuing delay up to the increase point and a graph that represents the queuing delay after the increase point, and by finding a function that is applicable to each graph after the division, A plausible graph division point is searched and detected as an increase point. The function may be a straight line or a curve. For example, while changing the graph division point k (k is the test packet number), the queuing delay to the graph division point k is approximated by a straight line W1, and a graph representing the queuing delay after the graph division point k is represented by a straight line or a curve W2. Approximate. Then, the graph division point k that is the approximation result with the least residual is set as the increase point.

  FIG. 4 is a block diagram illustrating a configuration example of the receiving terminal 20 illustrated in FIG. In FIG. 4, the reception terminal 20 includes a reception unit 21, an increase point determination unit 22, and an available bandwidth estimation unit 23.

  The receiving unit 21 receives the test packet transmitted from the transmitting terminal 10. In addition, the reception unit 21 acquires the queuing delay 101 of each test packet. The queuing delay 101 of each test packet is notified to the increase point determination unit 22.

Here, an example of a method for acquiring the queuing delay 101 will be described. Transmission time information s _j is added to each test packet transmitted from the transmission terminal 10 (j = 1, 2,..., N + 1). The transmission time information of the test packet with the test packet number “p_no = j” is s _j . The receiving unit 21 calculates the queuing delay of each test packet by the following equation.
q _i = (r _{i + 1} −r ₁ ) − (s _{i + 1} −s ₁ )
Here, q _i is the queuing delay (seconds) of the “i + 1” -th test packet (i = 1, 2,..., N). r _j is the reception time information of the test packet with the test packet number “p_no = j” (j = 1, 2,..., N + 1). The reception time information r _j is recorded by the receiving unit 21 when the test packet is received. Thereby, the graph data of the queuing delay with respect to the test packet number illustrated in FIG. 2 is acquired.

  The increase point determination unit 22 determines an increase point based on the queuing delay 101 of each test packet notified from the reception unit 21. The increase point 102 of the determination result is notified to the available bandwidth estimation unit 23.

  The available bandwidth estimation unit 23 sets the transmission rate of the test packet corresponding to the increase point 102 notified from the increase point determination unit 22 as an available bandwidth estimation value. As the transmission rate of the test packet, the transmission rate used by the transmission terminal 10 may be calculated in the reception terminal 20 or may be obtained from another device such as the transmission terminal 10.

  FIG. 5 is a block diagram illustrating a configuration example of the increase point determination unit 22 illustrated in FIG. In FIG. 5, the increase point determination unit 22 includes a first approximation processing unit 221, a second approximation processing unit 222, and a determination unit 223.

  The first approximation processing unit 221 calculates a straight line W1 that approximates the queuing delay 101 to the graph division point k, and calculates a residual between the straight line W1 and the queuing delay 101 to the graph division point k. The second approximation processing unit 222 calculates a straight line or curve W2 that approximates the queuing delay 101 after the graph division point k, and calculates a residual between the straight line or curve W2 and the queuing delay 101 after the graph division point k. calculate.

  The determination unit 223 acquires the residual of the first approximation processing unit 221 and the residual of the second approximation processing unit 222 at each graph division point k while changing the graph division point k, and the residual of the first approximation processing unit 221 is obtained. The graph division point k that minimizes the sum of the difference and the residual of the second approximation processing unit 222 is set as the increase point 102.

  Next, the operation of the increase point determination unit 22 shown in FIG. 5 will be described with reference to FIG. FIG. 6 is a flowchart showing the procedure of an increase point determination process according to the present embodiment.

(Step S1) The determination unit 223 sets the graph division point k to an initial value. The graph division point k is notified to the first approximation processing unit 221 and the second approximation processing unit 222. k is a test packet number p_no (p_no is a natural number from 1 to “N + 1”), and “1 <k ≦ N−2”. The number of test packets is “N + 1”. For example, “k = 2” is set as the initial value of the graph division point k. The reason for “k ≦ N−2” is to secure three or more sample data (queuing delay) in the approximate calculation after the graph division point k.

(Step S2) The first approximation processing unit 221 calculates a straight line W1 that approximates the queuing delay 101 to the graph division point k, and calculates a residual between the straight line W1 and the queuing delay 101 to the graph division point k. calculate. Specifically, the straight line W1 is assumed to be “y = a”. The value of a is calculated by the least square method so that the total sum of residuals between “y = a” and each queuing delay 101 up to the graph division point k is minimized. Next, the determination unit 223 is notified of the total difference Δ_1 of “y = a” and each queuing delay 101 up to the graph division point k.

(Step S3) The second approximation processing unit 222 calculates a straight line or curve W2 that approximates the queuing delay 101 after the graph division point k, and the queuing delay 101 after the straight line or curve W2 and the graph division point k. The residual of is calculated. Specifically, the straight line or the curve W2 is a quadratic function “f (x) = bx ² + cx + d”. However, x is a test packet number p_no after k, and “k <x ≦ N + 1”. The values of the coefficients b, c, d are calculated by the least square method so that the total sum of residuals between “f (x) = bx ² + cx + d” and each queuing delay 101 after the graph division point k is minimized. To do. Next, the determination unit 223 is notified of the total sum Δ_2 of “f (x) = bx ² + cx + d” and each queuing delay 101 after the graph division point k.

(Step S4) The determination unit 223 determines the sum of the residual sum Δ_1 by the first approximation processing unit 221 and the residual sum Δ_2 by the second approximation processing unit 222 at the graph division point k (total residual Sk and Calculated). The determination unit 223 records the total residual Sk at the graph division point k.

(Step S5) The determination unit 223 determines the end of the change of the graph division point k. When the change of the graph division point k is completed, the process proceeds to step S7, and when the change of the graph division point k is not yet completed, the process proceeds to step S6.

(Step S6) The determination unit 223 updates the graph division point k, and notifies the first approximation processing unit 221 and the second approximation processing unit 222 of the updated graph division point k. As a method for updating the graph division point k, for example, the value of k is increased by a predetermined value.

(Step S7) The determination unit 223 determines the increase point 102 based on the total residual Sk at each graph division point k. Specifically, the graph division point k having the smallest total residual Sk is set as the increase point 102.

  According to the embodiment described above, the position of the increase point varies greatly depending on the determination parameter (the value of the constant d in the determination condition of the Pathchirp method) as in the increase point determination method using the determination condition of the conventional Pathchirp method. Absent. As a result, it is possible to improve the accuracy of determining the increase point, and it is possible to keep the estimation accuracy of the usable bandwidth good.

  As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the specific structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.

  For example, as a method of changing the transmission rate of the test packet, (1) changing the transmission interval of the test packet, (2) changing the packet size of the test packet, (3) both the transmission interval and the packet size of the test packet Can be mentioned. The present invention can be applied to any of these methods, and the above-described effects can be obtained in the same manner. Note that the packet size of the test packet can be easily calculated by dividing the transmission rate by the transmission interval.

  The receiving terminal 20 may be a mobile communication terminal device such as a smartphone or a tablet computer (tablet PC), or a stationary communication terminal device (for example, a stationary personal computer).

  In the above-described embodiment, the case where the available bandwidth between communication terminals (end-to-end of a communication network) is measured is taken as an example. However, the available bandwidth between communication relay devices or between a communication terminal and a communication relay device is set as an example. The same applies to measurement.

In addition, when a wireless section is included between communication devices that are the target of measurement of usable bandwidth, there is a possibility that noise (abnormal value) is included in the measurement result of cueing delay due to the influence of radio wave interference or fading. is there. When such noise is observed, the calculation result of the queuing delay calculated by the receiving terminal 20 becomes a larger value. Therefore, in order to suppress the influence of the noise, an approximation function may be obtained by assigning a weight to data having a smaller queuing delay value than data having a large queuing delay value. Specifically, as the sum of squares of errors in the least squares method, “the square sum of errors Δ ₁ in the least squares method in the first approximation processing unit 221” and “errors in the least squares method in the second approximation processing unit 222 are calculated. The square sum Δ ₂ ”is calculated by [Equation 1] based on the absolute value of the queuing delay value q _i .

  Further, in the approximation process of steps S2 and S3 in FIG. 6, an approximation line or an approximation curve may be calculated by assigning a larger weight to the residual at the graph division point k than the other residuals.

  7 and 8 are graphs for explaining the approximation processing according to the embodiment of the present invention. In FIG. 7, when the residual is not weighted as in the above-described embodiment, the straight line W11 that approximates the queuing delay 101 up to the graph division point k and the queuing delay 101 after the graph division point k are approximated. A straight line or a curved line (here, a curved line) W21 is calculated. In this case, if there is a large difference in the queuing delay 101 before and after the graph division point k as in the graph point 301 and the graph point 302 in FIG. 7, the straight line W11 and the curve W21 are connected as shown in FIG. There is a possibility that a large discrepancy occurs in the eyes and the detection accuracy of the increase point is lowered.

  Therefore, in the approximation process of steps S2 and S3 in FIG. 6, an approximation line or an approximation curve is calculated by assigning a larger weight to the residual at the graph division point k than the other residuals. As a result, as shown in FIG. 7, at a certain graph division point k, a curve that approximates the queuing delay 101 after the graph division point k becomes a curve W22. In the curve W22, the divergence of the joint with the straight line W11 that approximates the queuing delay 101 to the graph division point k is smaller than the unweighted curve W21, and the detection accuracy of the increase point is improved. Alternatively, as shown in FIG. 8, at a certain graph division point k, a straight line approximating the queuing delay 101 up to the graph division point k is a straight line W12. In the straight line W12, the divergence of the joint with the curve W21 that approximates the queuing delay 101 after the graph division point k is smaller than the unweighted straight line W11, and the detection accuracy of the increase point is improved.

  In the approximation processing in steps S2 and S3 in FIG. 6, the residual weight may be set such that the residual at the graph division point k is given a higher weight than the other residuals, or the graph division point k. A larger weight may be given to the residual in a predetermined range in the vicinity of the graph division point k including the other residuals.

  Further, the computer program for realizing each step shown in FIG. 6 is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into the computer system and executed to thereby determine the increase point. Processing may be performed. Here, the “computer system” may include an OS and hardware such as peripheral devices.

  “Computer-readable recording medium” refers to a flexible disk, a magneto-optical disk, a ROM, a writable nonvolatile memory such as a flash memory, a portable medium such as a DVD (Digital Versatile Disk), and a built-in computer system. A storage device such as a hard disk.

Further, the “computer-readable recording medium” means a volatile memory (for example, DRAM (Dynamic DRAM) in a computer system that becomes a server or a client when a program is transmitted through a network such as the Internet or a communication line such as a telephone line. Random Access Memory)), etc., which hold programs for a certain period of time.
The program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the “transmission medium” for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line.
The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, and what is called a difference file (difference program) may be sufficient.

DESCRIPTION OF SYMBOLS 1 ... Usable band measurement system, 10 ... Sending terminal, 20 ... Receiving terminal, 21 ... Receiving part, 22 ... Increase point determination part, 23 ... Usable band estimation part, 221 ... 1st approximation process part, 222 ... 2nd approximation process Part, 223 ... determination part

Claims (7)

An increase point determination device for determining an increase point of a queuing delay used in measurement of an available bandwidth between communication devices of a communication network performed while increasing a transmission rate of a test packet;
A first approximation processing unit for approximating a queuing delay to a graph division point of a graph representing the queuing delay of the test packet by a first function;
A second approximation processing unit that approximates a queuing delay after the graph division point with a second function;
A determination unit that uses the graph division point that is the approximation result with the least residual as an increase point;
An increase point determination device comprising:   2. The approximation is performed by weighting a predetermined range in the vicinity of the graph division point or the graph division point including the graph division point with a larger weight than other ranges. Increase point determination device.   3. The increase point determination device according to claim 1, wherein the first function is a straight line, and the second function is a straight line or a curve.   When a wireless section is included between the communication devices that are the targets of measurement of the available bandwidth, weight is given to data having a small queuing delay value rather than data having a large queuing delay value, and The increase point determination apparatus according to claim 1, wherein a function of 1 and the second function are obtained. A receiving unit that receives each test packet transmitted at an increasing transmission rate and obtains a queuing delay of each test packet;
The increase point determination apparatus according to any one of claims 1 to 4, wherein an increase point is determined based on a queuing delay of each acquired test packet.
An available bandwidth estimator that uses the transmission rate of the test packet corresponding to the increase point of the determination result as an available bandwidth estimate;
A communication apparatus comprising: An increase point determination method of an increase point determination device that determines an increase point of a queuing delay used in measurement of an available bandwidth between communication devices of a communication network performed while increasing a transmission rate of a test packet,
A first approximation processing step in which the increase point determination device approximates a queuing delay to a graph division point of a graph representing the queuing delay of the test packet by a first function;
A second approximation processing step in which the increase point determination device approximates a queuing delay after the graph division point by a second function;
The increase point determination device determines the graph division point that is the approximation result with the least residual as an increase point; and
The increase point determination method characterized by including. A computer of an increase point determination device that determines an increase point of a queuing delay used in measurement of an available bandwidth between communication devices of a communication network performed while increasing a transmission rate of a test packet.
A first approximation processing step of approximating a queuing delay to a graph division point of a graph representing the queuing delay of the test packet by a first function;
A second approximation processing step for approximating a queuing delay after the graph division point with a second function;
A determination step in which the graph division point that is the approximation result with the least residual is the increase point;
A computer program for running.

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