JPH04355535A - Atm call reception controller - Google Patents

Abstract

PURPOSE:To avoid a low operating rate in an ATM network by measuring directly a flow of a cell so as to decide the acceptability of the reception in the presence of a call connection request. CONSTITUTION:The controller is provided with a counter 51 for counting number of cells reached within a unit time, a device 52 calculating a mean cell number from the result of measurement and revising and storing the result, a device 54 converting the result of measurement of a cell number into the cell number arrival distribution, and a device 55 or the like revising and storing the result obtained by the device 54. The distribution of cells reached within a prescribed time is estimated by storing and converting the result of measurement. Moreover, the arrival cell number within a prescribed time of the terminal equipment from the application from the terminal equipment is estimated and the result is added onto the distribution based on the result of measurement to estimate the distribution of the arrival cell number within a prescribed time when a connection request terminal equipment is tentatively accepted. The cell abort rate estimate value is obtained from the distribution and the acceptability is decided.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to ATM (Asynchronous
Transfer Mode (Asynchronous Transfer Mode) relates to a call admission control device of an exchange in a network, and is particularly suitable for determining whether or not to accept a call with high quality and at high speed.
This invention relates to a call admission control device for an exchange in the M network.

0002

[Prior Art] Currently, ISDN (Integrate) is a system that aims to integrate data communication at a rate of about 64 kilobits/second.
d Services Digital Net
(Integrated Services Digital Network), with channel speeds of 1.5 megabits/second. On the other hand, in response to this, the development of broadband ISDN is underway, which allows not only telephone and personal computer communications, but also video conferencing with high-definition images and file transfers at tens of megabits per second using a single line interface.

[0003] The target of such broadband ISDN is multimedia information. To this end, broadband IS
DN is required to meet a wide variety of quality conditions as shown below. (1) Telephone calls, video conferences, etc. have strict requirements for transmission delay time. (2) Data communications have strict requirements for errors.

[0004] Conventional switching methods such as circuit switching and packet switching cannot satisfy these requirements, and one method for uniformly and efficiently transmitting such a wide variety of information is the following: ATM (Asynchronous
TransferMode, asynchronous mode).

[0005] ATM divides a wide variety of information into short, fixed-length blocks with headers called "cells," and multiplexes each block using an efficient statistical multiplexing method. A cell is a concept similar to a time slot, but it does not appear periodically, but is allocated dynamically in response to time-varying requests for information transmission, and by changing the number of cells, the communication speed can be set variably. Therefore, ATM is a transfer mode that makes it possible to centrally transmit all kinds of digital information, from voice and data to images. Furthermore, since the beginning of a fixed-length cell appears at a specific timing, the channel can be identified at high speed using hardware or the like based on the label at the beginning, making it suitable for speeding up overall processing.

[0006] In this way, with ATM, it is only necessary to put the necessary number of pieces of information in a cell depending on the generation of information, and information can be transferred at any transmission speed. Furthermore, there is the advantage that the amount of generated information can be made variable in accordance with changes in the image, and image quality can be kept constant. A communication network that performs communications based on this ATM is called an ATM network.

FIG. 2 is a block diagram of a communication system that constitutes a conventional ATM network.

Refer to the same figure. The ATM network includes terminals 31 to 37 that users use for communication, ATM exchanges 38, 39, and 310 that control connections between the terminals 31 to 37, and
It is constituted by a link 311 connecting ATM exchanges 38, 39, and 310. In this way, ATM exchange 3
8, 39, and 310 are mutually connected by a link 311, and the terminals 31 to 37 are accommodated in one of the ATM exchanges 38, 39, and 310. Further, the ATM exchanges 38, 39, and 310 are the ATM exchange 3 shown in FIG.
8, a switch section 312, output buffers 313, 314, and a call admission control section 315.
Based on the control operation of the call admission control section 315, cells arriving from the input link are exchanged by the switch section 312, and sent to the output link via the output buffers 313 and 314.

FIG. 4 is a sequence diagram showing the operation of call admission control within the ATM network in FIG.

This figure shows a terminal 31 in the ATM network of FIG.
3 shows a procedure for controlling connection of a call from to the exchange 310. That is, when connecting a call, first, the terminal 31 connects the switch 31 to the
0, a connection request 1102 is made by the calling cell 1101.
Do the following. Based on this connection request 1102, the exchange 31
If it is 0, acceptance determination 1103 is made. After the switch 310 responds with a judgment result indicating that the call is acceptable 1104 and the connection is permitted, cells 1105 of the required amount corresponding to the call flow within the network. The connection is then terminated by sending out the open cell 1106.

As shown in FIGS. 2 and 4, in an ATM network, when a call connection is requested, a cell containing information regarding the connection request is processed in a call admission control unit in the exchange, and it is determined whether the call can be connected or not. It can be decided. After the call is accepted, the call flows through the network in the form of cells. However, at this time, since the output buffer within the exchange can accommodate only a certain number of cells or less, if the amount of incoming cells is excessive, cells will be discarded. Since this cell discard degrades communication quality, it is necessary in call admission control to determine whether the cell discard rate in the output buffer is within an allowable range for deterioration of communication quality.

[0012] In call admission control, if a connection request call is received, in order to determine whether the cell discard rate in each output buffer is below a predetermined cell discard rate regulation value,
Use declared parameters for each call. The declared parameters are information on the amount of cells in which the call in question occurs, such as average, peak (minimum cell interval), maximum number of cells arriving within a certain period of time, etc.

[0013] Conventionally, methods for determining the upper limit of the cell discard rate from the distribution of the number of cells arriving within a certain period of time include [1] Hiroshi Saito, “Simplified dimension
ng method of ATM networks
”, IEICE technical report SSE89-112 [2] Hiroshi Saito, “Call admission co.
Trol in an ATM network
ithoutusing traffic measurement
rement”, Institute of Electronics, Information and Communication Engineers Technical Report SSE89-1
55 [3] Hiroshi Saito, “New dimensionig”
concept for ATM networks”
, ITCS Specialist Seminar, 1
990. [4] There is Japanese Patent Application No. 2-31782.

[0014] In these methods, the cell discard rate is estimated on the safe side by a weighted sum of the distribution of the number of cells arriving within a certain period of time. In addition, as a method to eliminate the complexity of weighted sum calculation,
In the above-mentioned [2] and [5] Japanese Patent Application No. 2-31781, the following quantities are introduced. Let Q(i) be the probability that the number of cells arriving within a certain time is greater than or equal to i (complementary distribution of the number of arriving cells).

[0015]

Define as [Equation 2]. It is easier to construct an estimator based on S(i) (depending on the weight) than to directly calculate the weighted sum of the cell number distribution.

[0016]

[Problem to be Solved by the Invention] In the ATM network, bandwidth is allocated based on the declared value, regardless of the user's actual usage status. During actual use, the user must
Sending cells that exceed the declared value is considered a violation of declaration, so it is thought that over-reporting will result in a low utilization rate within the network.

An object of the present invention is to provide an ATM call admission control device that can overcome the above-mentioned drawbacks by directly measuring the cell flow rate.

[0018]

[Means for solving the problem] A means for counting the number of cells added to an output link during a predetermined measurement time length T, storing the measurement result, and converting it into an appropriate statistical data form using an arithmetic calculator. , means to update the results at regular intervals, and when requesting a call connection, estimate from the declared value how many cells will arrive from the terminal within the measurement time length T (if declared). an ATM call admission control device, a device that estimates a cell discard rate by combining a series of results using the above-mentioned measured values, and a device that determines whether or not a call can be accepted based on whether the estimated value is greater than or equal to a specified value. was constructed.

[0019]

[Operation] Since the present invention includes a device that measures the distribution of the number of cells arriving within a certain period of time, the actual usage status of users can be known and low usage rates of network resources can be avoided. Furthermore, the measuring device is a counter, and can be easily implemented for high-speed cell transfer. Furthermore, by storing and converting the measurement results, the distribution of the number of cells arriving within a certain period of time or S(i) described in the prior art can be estimated from the measurement values. Also, since there is an update method, this will change to something new.

[0020] From the declaration from the terminal, the number of cells arriving at the terminal within a certain period of time can be estimated, and by adding this effect to the distribution based on the above measurement results and the estimation result of S(i),
It is possible to estimate the distribution (or S(i)) of the number of cells arriving within a certain period of time, assuming that a connection requesting terminal is accepted. Based on the distribution and S(i), an estimated value of the cell discard rate is obtained using a method known in the prior art, and a decision is made as to whether or not to accept the cell.

Therefore, if there is no estimation error in the distribution or S(i), the reception control device is always evaluated on the safe side (quality can be maintained). Further, in the first embodiment, a weighted sum is used, which is easy to process in the conversion device. In Example 2, S
The device configuration is such that the configuration (i) is easy.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing the details of the configuration of a call admission control device as an embodiment of the present invention. 51 in the figure is
52 represents a device that counts the number of cells arriving within a unit time T; 52 is a device that calculates the average number of cells arriving within a unit time T from the measurement results and updates and stores the results;
3 is a device that takes into account the average change due to the call when a call connection (acceptance) request is made.

54 is a device that converts the measurement result of the number of cells into the arrival number distribution of the number of cells; 55 is a device that updates and stores the result obtained in 54; and 56 is a device that updates and stores the result obtained in step 54; 57 is a device for estimating the number of cells discarded by the weighted sum of the distribution of the number of arriving cells; 58 is a device for estimating the number of cells discarded by dividing the number of cells arriving by the number of arriving cells; The cell discard rate estimation device 59 is a device that compares whether the cell discard rate estimated value is larger or smaller than the specified value stored in 510.

A first embodiment of the configuration of each device shown in the drawings is shown in FIGS. 6 to 13. FIG. 6 shows the configuration of the device 52 in FIG. In FIG. 6, a memory 61 is a device for storing the result of the cell number counter, an average calculator 62 is a device for obtaining the arithmetic mean of the contents of the memory 61, and a weighted sum device 63
is the output (x62) of the average calculator 62 and the average holding memory 6
Weighted average with the contents of 4 (x64) [a・x62+(1-
a)x64] and writes it into the average holding memory 64 (a is a constant given in advance).

FIG. 7 shows the configuration of the probability generator 54 in FIG. 1. In FIG. 7, a threshold holding memory 71 is a device for storing several predetermined threshold values, an update cycle holding memory 72 is a device for storing a predetermined constant (representing an update cycle), and a comparator 73 is a memory. A device for comparing the threshold value stored in 71 with the measured value of the number of cells, an adder 74, 7
6 generally represents the number of thresholds stored in memory 71 (or
+1), the measurement result of the number of cells is more than ki+
If it is less than 1 (ki and ki+1 are respective threshold values), the content of the corresponding adder is set to +1, and this is stored.

There are the same number of dividers 75 and 77 as the adders 74 and 76, and the results of the adders 74 and 76 are stored in the memory 72.
The maximum value holding memory 78, which is a device that creates the distribution of the number of arriving cells in the update cycle by dividing by (update cycle), stores the maximum number of arrivals within the update cycle, and when a new measurement result is obtained. , and compares it with the current value, and if it is larger, it is rewritten and stored as the maximum value.

FIG. 8 shows the configuration of the probability distribution update device/holding memory 55 in FIG. In FIG. 8, there are the same number of weighted sum adders 81 and 82 as adders 74 and 76 and dividers 75 and 77, and the result of dividers 75 and 77 is the distribution of the number of arriving cells (one The output of the divider is a device that calculates the weighted sum of the probability of arrival of cells greater than or equal to ki and less than ki+1) and the distribution of the number of arriving cells thus far stored in the memory 84. (
The weights of each weighted sum adder are all the same and predetermined, and are greater than or equal to 0 and less than or equal to 1, and the sum of the weights is 1. )

0
The weighted sum adder 83 is a device that calculates a weighted sum of the maximum number of arriving cells in the latest update cycle and the memory 85 that stores the maximum number of arriving cells so far. The memory 84 is a device for storing the outputs of the weighted sum adders 81 and 82, and the memory 85 is a device for storing the output of the weighted adder 83.

FIG. 9 shows another configuration of the probability distribution update/holding memory 55 in FIG. In FIG. 9, memory 9
Numerals 1 and 93 have the same number of adders 74 and 76 and dividers 75 and 77 of the probability generator 54, and are a device for storing the outputs of a certain number of dividers 75 and 77 from the newest one, an average calculation device 92,
94 is a device for obtaining the arithmetic mean of the contents in each memory 91 and 93; probability distribution holding memory 9;
Reference numeral 5 denotes a device that stores the outputs of the averaging devices 92 and 94 as a distribution of the number of arriving cells.

The memory 96 is reset every j' update cycles, and if the result of the maximum value memory 78 is larger than the content of the memory 96, it is stored in the memory 96 as the maximum value. The comparator 97 is connected to the maximum value memory 78 described above.
This is a device that compares the size of the memory 96 and the memory 96. memory 98
A comparator 99 is a device that stores the value immediately before the reset of the memory 96 for a fixed number of times, and a comparator 99 is a device that compares the maximum value of the memory 78 and the memory 96 obtained as a result of the comparator 97 with the maximum value of the memory 98.

FIG. 10 shows the configuration of the connection request convolution device 56 in FIG. 1. In this embodiment, it is assumed that the notification from the terminal is the peak (minimum cell interval) or the maximum number of cells in a certain period of time, and based on the declared value, the maximum number of arriving cells within a unit time T from the terminal can be easily determined. It is possible to calculate In addition, when determining call acceptance, only the effect of the maximum number of arriving cells within T is considered, and the average etc. are not considered even if reported. (If this is to be considered, it will be discussed later.)

00
[32] In a situation where there is no notification, the network side shall appropriately assume the maximum number of arriving cells from the terminal. In FIG. 10, an adder 101 stores the maximum number of arriving cells (device 102) from a connection (acceptance) request call to the maximum value in memory 85 or 99.
The device 102 is a device that calculates the maximum number of cells that arrive within a unit time T from the terminal based on the declared value.For example, in the case of peak (minimum cell interval) declaration, it uses a divider and round-up ( (integerization). (The configuration of this device is clear)

The threshold value holding memory 103 is a storage device having exactly the same contents as the threshold value holding memory 71, and the adder 104 is a device that adds the maximum value obtained by the device 102 to all the threshold values stored in the memory 103.

FIG. 11 shows the configuration of the weighted sum adder 57 in FIG. In FIG. 11, a multiplier 111 is a device that multiplies contents of the memory 84 or 95 that meet the conditions of a comparator 113 by a subtracter 112;
A device for subtracting a constant value r (the number of cells that can be transferred by the output link within T) from the output of the adder 101 in FIG.
The comparator 113 is a device that compares the outputs of the adders 104 and specifies the maximum threshold value (after addition) that is equal to or less than (r+1).

The operation of this embodiment is shown in a flowchart (FIG. 12).
, 13). Here, the configuration of the probability distribution update/holding memory 55 is shown in FIG. 8.

In FIG. 12, in S121, the counter 51 counts the number of cells arriving within a unit time T. The obtained results are stored in the memory 61 in S122. At the same time, in S127, the comparator 73 determines that the measurement result is greater than or equal to the threshold value k (the threshold value is in the device 71), and in S128, the adder 74 (or 76) corresponding to the threshold value Add 1 to the content. (Specifically, if the threshold value is 10, two adders are prepared: one that represents the number of times the number of arriving cells is 0 or more, and one that represents the number of times that the number of arriving cells is 10 or more. Update synchronization (
j measurement times). Update cycle and measurement cycle T
Please refer to the relationship shown in FIG. 0 or more 10
If it is less than 10, add 1 to one adder, and if it is 10 or more, add 1 to both adders. Further, in S1212, it is determined whether the measurement result is larger than the content stored in the memory 78, and if it is larger, it is written to the memory 78 in S1213.

In S123, it is determined that k contents of the memory 61 have been collected, and if they have been collected, the average of them is obtained by the device 62 in S124. The contents of memory 61 are reset. In order to estimate the average over k or more measurement interval lengths, in S125, the weighted sum device 63 performs the weighted sum device 63 in S124.
A weighted sum having a predetermined weight is calculated from the results obtained in step 2 and the contents of the average holding memory 64. In S126, it is stored in the memory 64 as a new average estimate.

On the other hand, it is determined in S129 that j measurements (one update period) have elapsed, and in S1210 each adder 74
, 76 is divided by j (dividers 75, 77). This provides a probability distribution within the update period. The contents of each adder are reset. In order to take into account fluctuations in the distribution of the number of arriving cells over j measurements (one update cycle) or more, the distribution information on the number of arriving cells (contained in the form of a probability of greater than or equal to ki and less than ki+1) in the memory 84 and the information obtained in S1210 are used. The weighted sum adders 81 and 82 add weighted sums to each value of the probability distribution (for example, a value greater than or equal to ki and less than ki+1) (S1211
). (Specifically, when the threshold value is 10, the 0 obtained in S1210
The above probability and the probability of 0 or more in the memory 84 are added with weight, and the probability of 10 or more obtained in S1210 and the probability of 0 or more in the memory 84 are added.
Take the weighted sum of the probabilities of 10 or more in 4. )

0
[039] In S1211, the obtained addition result is stored in the memory 84.
will be replaced with the contents of If it is determined in S1214 that the measurement is j times, the contents of the memory 78 are reset in S1216, and at the same time, the contents of the memory 78 are reset in S1215.
A weighted sum of the contents (just before the reset) and the contents in the memory 85 is obtained by the device 83 and overwritten in the memory 85 as a new estimate of the maximum value.

FIG. 13 shows a case where a call connection request is made in steps S131 and subsequent steps. In S132, the device 53 calculates the maximum number of arriving cells within T generated from the requested call using the device 102, based on the declared value of the requested call. In S133, the adder 101 adds the maximum value 85 and the contents of the device 102. In S134, it is determined that the result of S133 is larger than the constant r stored in the memory 114, and if it is larger, in S135, the subtracter 112
Subtract r from the result of 33.

On the other hand, in S1313, the result of the device 102 is added (adder 104) to the threshold value (memory 103). In S1314, the comparator 113 extracts the content stored in the memory 84 corresponding to the largest one less than or equal to the constant (r+1) among the results in S1313. (Specific example: When the threshold is 10, 20, the probability of 0 or more is 1
, the probability of 10 or more is 0.3 and the probability of 20 or more is 0.1 is stored in the memory 84, and the maximum value is 10, r=19. According to S1313, the estimated distribution of the number of arriving cells after the connection request call is accepted has a probability of 1 or 2 with a probability of 10 or more.
0 or more and 0.3, 30 or more and 0.1. Since r=19, the maximum break below 20 is 20, and the corresponding probability of 0.3 is extracted. )

In S136, the result of S135 is multiplied by the contents of the memory 84 extracted in S134. After adding the result of S132 to the contents of the average holding memory 64 in S1315 (device 53), the result of S136 is divided by the output of device 53 by the divider 58 in S137. In S138, the comparator 59 compares the result of S137 (output of the divider 58) with the memory 5.
Compare the specified values within 10. If it is larger than the specified value, acceptance will be refused (S1316). Acceptable if the specified value is small (
S139) and overwrites the contents of S133 in the memory 85 as the estimated maximum value after accepting the call (S1310).
, the probability distribution 84 is overwritten as the estimated value of the probability distribution in a form corresponding to S1313 (S1311), and the result of S1315 is overwritten in the average holding memory.

[0043] However, S1310, S1311, S131
2 may not be carried out if there are no declared values or if they are unreliable. (To be specific about the example of S1311, since the threshold values are 10 and 20, when the probability of 0 or more is 1, 10 or more 0.7, 20 or more 0.9, the maximum value = 10, S13
13, 10 or more 1, 20 or more 0.7, 30 or more 0.9
Suppose that it becomes The original threshold is 10, 20, so S13
11 overwriting is 0 or more probability 1, 10 or more probability 1, 20
The above probability is 0.7. )

A second embodiment will be described. FIG. 14 shows the configuration of a call admission control device as a second embodiment of the present invention. The device 141 is a counter for the number of arriving cells, and the device 142 is a device that converts the measurement result of the device 141 into a sum that is greater than or equal to a threshold of a complementary distribution of the number of arriving cells. The device 143 updates and stores the load state vector obtained by the device 142. device 144
is a device that takes into account the number of arriving cells from the call when requesting a call connection (acceptance), and a device 145 estimates the cell discard rate by dividing the estimated value of the number of discarded cells obtained by the device 144 by the estimated value of the number of arriving cells. The comparator 146, which is a device for obtaining a value, is a device that compares the estimated cell discard rate with a specified value stored in the memory 147.

Device 142 is similar to devices 52 and 5 in FIG.
4, the device 143 corresponds to the device 55, and the device 144 corresponds to the devices 53, 56, and 57. The device 145 is the device 58,
Device 146 is equivalent to device 59 and device 147 is equivalent to device 510.

FIG. 15 shows the configuration of the load state vectorization device 142 of FIG. 14. In FIG. 15, a threshold value holding memory 151 stores a predetermined threshold value. A predetermined update cycle j is stored in the device 152. The comparator 153 is a device that compares the measurement result of the counter 141 with a threshold value stored in the memory 151 and specifies the element of the load state vector to be updated. Adder 154
, 156, there are (+1) threshold values held in the memory 151, each of which corresponds to an element of the load state vector.

When the result of the cell number counter 141 is x, the adder corresponding to the threshold m is determined by the comparator that x≧m
If it is determined that (x
-m+1). Dividers 155 and 157 are adder 1
54,156 on a 1:1 basis, and every j measurements (1
This is a device that divides the adders 154 and 156 by j after an update period) to obtain a load state vector.

FIG. 16 shows the configuration of the load state vector updating device and holding memory 143 of FIG. 14. In FIG. 16, weighted sum addition devices 161 and 162 include a divider 155,
157 and 1:1 correspondence, dividers 155, 157
This is a device that weights and averages each element of the latest load state vector obtained from the previous load state vector and each element of the weighted average of the past load state vectors in the memory 163, and the result is overwritten in the memory 163 again. .

FIG. 17 shows the configuration of the connection request call probability distribution convolution device and weighted sum adder 144 of FIG. Figure 17
When there is a connection request, the devices 173, 174, and 1712 determine the maximum, average, and average/average number of cells arriving within T from the connection request call, based on the declared value of the connection request call.
This is a device that estimates the maximum. (As for the maximum, an example is given in the first example. As for the average, for example, if a medium time throughput is declared, it is converted to a throughput within T. Usually, these devices The structure is clear.)

The subtracter 172 is a device that subtracts the result obtained from the device 173 from 1, the multiplier 171 is a device that multiplies the result of the subtracter 172 and the element of the vector stored in the memory 163, and the comparator 176 is a device that compares the result (maximum value) of the device 174 with the threshold value stored in the threshold value memory 1713, and the subtracter 177 compares the result of the comparator 176,
If the threshold value is larger, subtract the maximum value that is the output of the device 174 from the threshold value, and store the result in the memory 16 as the threshold value.
This is a device that selects 3 elements. (When the threshold value i and the maximum value i', S(i-i'-) of the vector (S(0), S(1)...) in the memory 163 is extracted.) As a result, the device 173 is added to the selected element. Multiplier 178 multiplies the results of .

The subtracter 179 calculates that the output of the comparator 176 is
Adder 1710 is a device that subtracts the threshold value from the maximum value obtained by device 174 when the threshold value is small; This is a device that multiplies the result of adder 1710 by the result of device 173.

According to the flow chart (FIGS. 18 and 19),
Explain the operation. The counter 141 measures the number of cells arriving within unit time T (S181). For convenience of the above explanation, this measured value is assumed to be x. The i-th element of the load state vector is Q(i)+Q, where Q is the complementary distribution of the number of arriving cells.
(i+1)+... is represented. This will be referred to as S(i) in the following explanation.

In S182, since the measured value is x, the comparator 153 recognizes that elements 0 to x of the load state vector are affected. (Threshold value holding memory 151
For brevity of explanation, we will describe the case where the threshold values stored in the memory are 0, 1, 2, etc. in 1 increments, but in general, if this is not the case, the comparator 153 will compare the contents of the holding memory and the measured value. x are compared, and S184 is performed for the one corresponding to the threshold m that satisfies 0≦m≦x. )

In S184, the adder 15 corresponding to m that satisfies 0≦m≦x recognized by the comparator 153 in S183
Add (x-m+1) to all 4,156. (Adder 1
54,156 are each element of S(m) (S(0), S
(1),...). ) In S185, it is determined whether the measurement has reached a predetermined number of times j stored in the memory 152, and if it has, in S186, the value of each element (output of the adder) is divided by j. vessel 155,1
57 to reset the contents of each adder 154, 156.

[0055] The load state vector for j measurements (one update synchronization) has now been obtained. In order to reflect the measurement results over a length of j times or more, in S187, the weighted sum of the weighted average of the past load state vectors stored in the memory 163 and the current load state vector is taken for each element, and the result is The memory 163 is overwritten in S188.

If it is determined in S191 of FIG. 19 that there is a call connection request, in S192 the device 174
From the declared value, the maximum number of arriving cells for the call within T is MA
I understand X. In S193, it is determined whether the maximum value is larger or smaller than r (the number of cells that can be transferred by the output link within T).

On the other hand, in S196, the device 173 estimates the average/maximum number of arriving cells for the requested call. S
At 197, the result v of device 173 is subtracted by subtractor 172
(1-v), which is multiplied by the multiplier 171 with the element S(r) corresponding to the threshold r in the memory 163. S
In S193, if the output MAX of the device 174 is less than r, in S194, the subtracter 177 calculates (r
-MAX) is executed, and element S(r-M
AX) is extracted, and a multiplier 178 calculates vS(r-MAX) for the output v of the device 173 and the element S(r-MAX).
is executed.

In S193, the output MAX of the device 174 is
is larger than r, in S195, the subtractor 17
9 executes (MAX-r), extracts the element S(0) of the memory 163, and adds S(0)+ by the adder 1710.
MAX-r is executed, and multiplier 1711 performs unit 173
For the output v, obtain v(S(0)+MAX-r).

[0059] In S198, the result of S197 and
If r≧MAX, the result of S194 is added, and if r<MAX, the result of S195 is summed by the adder 175. S
The result of 198 is an estimated value of the number of discarded cells. S1
In step S199, in order to convert the estimated value of the number of discards into an estimated value of the discard rate, the average number of arrivals from all calls including connection request calls is calculated, and the result of S198 is divided by that. S(0) in the memory 163 is the average number of arriving cells (estimated value) from calls other than the connection requesting call, and the number of arriving cells from the connection requesting call obtained from the device 1712 is added, and the divider 14
Obtain the cell loss rate (estimated value) by dividing by 5 and calculate S1
Complete 99.

In S1910, the comparator 146 compares whether the result of S199 is larger or smaller than the specified value stored in the memory 147, and if it is larger, it is not accepted (S1911), and if it is smaller, it is judged to be acceptable (S1912). If the call is accepted, steps S1913 to S1 are performed to take into account the influence of the connection request call.
917 for all i (all i corresponding to threshold memory 151)
For this purpose, do the following:

In S1913, the result v of the device 173 is converted to (1-v) by the subtracter 172, and multiplied by S(i) in the memory 163 by the multiplier 171. S191
4, it is determined whether i is greater than the result MAX of device 174. If so, in S1916, the subtracter 177 executes (i-MAX) to extract S(i-MAX) in the memory 163, and the multiplier 178 executes the product vS(i-MAX) with the output v of the device 173. MAX). If it is small, in S1915, the subtractor calculates (MAX-i)
Execute, extract S(0) from memory 163, adder 17
10 executes MAX-i+S(0), multiplier 171
1, for the output v of measure 173, v(S(0)+MA
Execute X-r).

In S1917, the result of S1913 and S1
916 or the result of S1915, the judgment of S1914 (r
≧MAX or not). S1913-
S1917 is a step in which the influence caused by the addition of the connection request call is reflected and corrected in the contents of the previous load state vector. If there is no declared value or if it is unreliable, it may be omitted. Furthermore, a configuration in which the configurations of the first embodiment and the second embodiment are combined is also conceivable.

A third embodiment (ATM call admission control device) is shown in FIG. In the apparatus 2001 of FIG. 20, the number of cells to the output link is counted for each predetermined measurement time length T. Device 2002 (detailed diagram 21)
consists of a frequency counter 2101 that accumulates the frequency of arrival cell count=k1 as a result of the device 2001, and a memory 2103 that resets the counter and holds the cycle output by the device 2003 via the divider 2102. For example, if the number of cells arriving within T in device 2001 is 1, then q1'
The counter is incremented by 1. When the update period (denoted as j) stored in the memory is reached, the counter 2101
All values of are divided by j, resulting in data in the form of "How many times did cell k arrive in j times?" (This is written as qk)
.

All q0, q1, . . . are sent to the device 2003. At this time, the contents of the frequency counter 2101 are all reset. The device 2003 outputs the output of the device 2002 {q0
, q1,...} is estimated from past data (this is an estimator of the distribution of the number of arriving cells). Contents of memory 2202 {p0
, p1,...}, αqk+(1-α)Pk (k=0,1
, 2...) and replaces it with the content Pk of memory address k. As a result, the estimated value of the distribution of the number of arriving cells changes from the measurement results.

Devices 2004 to 2010 are devices that operate at the time of call acceptance determination. Device 2004 is a device that copies and stores the entire contents of memory 2202 in device 2003 when a call acceptance request occurs (call connection request occurs), and device 2005 (detailed diagram 23) stores the entire contents of memory 2202 in device 2003 when a call acceptance request occurs (call connection request occurs). This device estimates the distribution of the number of arriving cells after acceptance from the declared parameters and the current distribution of the number of arriving cells. From the declared values, the maximum number of cells (denoted as R) and the average number of cells (denoted as A) in which a connection request call occurs within time T are determined. (When reporting only the peak, it will be given only from R, but in that case A=R.)

For the contents of the memory 2202 in the device 2003, a multiplier 2303, a weighted sum adder 2304, and a comparator 2305 calculate (1-A/R)Pk.
...(for all k<R) (1-A/R)Pk+(A/R)Pk-R...(
For all k≧R), the following calculation is performed and the result is overwritten in the memory 2202. In other words, the address k of the memory 2202 is: (1-A/R)Pk k≧R if k<R at the time of a connection request
Then, it is updated by (1-A/R)Pk+(A/R)Pk-R.

With this update, the contents in the memory 2202 become an estimate of the distribution of the number of arriving cells immediately after the call is accepted. The device 2006 calculates the average value from the updated memory 2202, and specifically,

[Math 3] Calculate.

Weighted adder 2007 uses the contents of memory 2202 to

[Math 4] Perform the calculation.

The divider 2008 is a weighted sum adder 2007
By dividing the output by the average calculation device 2066, an upper limit estimate of the cell loss rate is obtained. A comparator 2009 compares this value with a predetermined value held in the memory 2010 to see if it is smaller, and if it is smaller, it outputs acceptance, and if it is larger, it outputs unacceptable. Memory 2202 only if reception is not possible
It is necessary to restore the contents of the backup memory 2004 to the contents of the backup memory 2004.

[0070]

[Effects of the Invention] As explained above, according to the present invention,
By directly measuring the cell flow rate, it is decided whether or not to accept a call connection request when a call connection request is received, so it has the advantage that there is no low usage rate in the ATM network as in the past. .

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a block diagram showing a communication system configuring an ATM network.

FIG. 3 is a block diagram showing an example of the configuration of an ATM switch.

FIG. 4 is a sequence diagram showing the operation of call admission control within an ATM network.

FIG. 5 is an explanatory diagram showing the relationship between an update cycle and a measurement cycle.

FIG. 6 is a block diagram showing details of block 52 in FIG. 1;

7 is a block diagram showing details of block 54 in FIG. 1. FIG.

FIG. 8 is a block diagram showing details of block 55 in FIG. 1;

9 is a block diagram showing details of another example of block 55 in FIG. 1. FIG.

10 is a block diagram showing details of block 56 in FIG. 1. FIG.

11 is a block diagram showing details of block 57 in FIG. 1. FIG.

FIG. 12 is a flowchart showing a part of the operational flow of the embodiment shown in FIG. 1;

FIG. 13 is a flowchart showing the remaining part of the operational flow of the embodiment shown in FIG. 1;

FIG. 14 is a block diagram showing another embodiment of the present invention.

15 is a block diagram showing details of block 142 in FIG. 14. FIG.

16 is a block diagram showing details of block 143 in FIG. 14. FIG.

17 is a block diagram showing details of block 144 in FIG. 14. FIG.

FIG. 18 is a flowchart showing a part of the operational flow of the embodiment shown in FIG. 14;

FIG. 19 is a flowchart showing the remaining part of the operational flow of the embodiment shown in FIG. 14;

FIG. 20 is a block diagram showing yet another embodiment of the present invention.

21 is a block diagram showing details of block 2002 in FIG. 20. FIG.

22 is a block diagram showing details of block 2003 in FIG. 20. FIG.

23 is a block diagram showing details of block 2005 in FIG. 20. FIG.

[Explanation of symbols]

51... Cell number counter, 52... Average update device and average memory, 53... Connection request call average addition value, 54... Establishment device, 55... Probability distribution update device and probability distribution holding memory, 5
6... Connection request call establishment distribution convolution device, 57... Weighted sum adder, 58... Divider, 59... Comparator, 510... Specified value holding memory

Claims (3)

[Claims] Claim 1: In an ATM switch, when a call connection request is received, in an ATM call admission control device that determines whether or not to accept the request, the ATM
a cell number measuring device that counts the number of cells added to an output link of an exchange; a storage device that processes the results counted by the measuring device to obtain temporal statistical data and stores the data while updating; When a call connection request is made, a holding device receives the number of cells scheduled to be sent declared from the terminal that issued the request and holds it as data on the number of expected cells to arrive, and statistical data read from the storage device. The discard rate of cells that will be discarded when the call connection request is accepted is determined from the data on the expected number of arriving cells retrieved from the holding device, the output link capacity of the ATM switch, and the output buffer capacity associated with the output link. and a determination device that compares the calculated discard rate with a predetermined value and determines whether or not the call connection request can be accepted based on the comparison result. Features: ATM call reception control device. 2. In the ATM call admission control device according to claim 1, when processing the results counted by the cell number measuring device to obtain temporal statistical data, the temporal statistical data is calculated according to the following formula. An ATM call admission control device characterized in that it obtains the following. Pk(t+1)=αqk(t)+(1-α)Pk(t)
However, Pk (t+1): Temporal statistical data to be obtained (frequency distribution of the number of arriving cells at time (t+1), i.e., the frequency representing how many times the event in which k cells arrived among the total number of measurements) distribution, k = 0,...,∞) Pk(t): Frequency distribution of the number of similar arriving cells at time t, known qk(t): Obtained as a measurement result over N unit times T from time t. The period [t, t+
NT] frequency distribution of the number of arriving cells α: coefficient in the range of 1 to 0 3. The ATM call admission control device according to claim 1, wherein when calculating the discard rate of the cell, the discard rate is determined according to the following formula. [Equation 1] However, B: Desired discard rate r: Number of cells Pk that can be transferred by the output link within unit time T
(t): Frequency distribution of the number of arriving cells at time t