JPH0879255A - Call reception control method and call reception controller - Google Patents

Abstract

PURPOSE: To provide a call reception control method and a call reception controller capable of evaluating a cell flow rate and a cell loss rate by less hardware resources and simple observation algorithm and satisfying fixed service quality. CONSTITUTION: These method and controller are constituted of an input/output means 110 for performing the transmission and reception of cells with an asynchronous transfer network 500, a buffer means 120 for tentatively storing the cells inputted from the asynchronous transfer network 500 through the input/ output means 110, a load state judgement means 130 for judging the load state of the input/output means 110 and a call reception judgement and control means 140 for judging whether or not a new call is to be received based on the judged result of the load state judgement means 130 and performing control.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a call admission control method and a call admission control device, and whether a new call is admitted when a plurality of call types are multiplexed on a definite link of an asynchronous transfer network. The present invention relates to a call admission control method and a call admission control device that determine whether or not to admit a new call based on the result of the determination.

[0002]

2. Description of the Related Art ATM (Async) for asynchronous transfer
In the “Hronous Transfer Mode”, V
A large number of VCs are accommodated in a VP (Virtual Path) having a definite capacity by utilizing burst transfer of information of C (Virtual Channel) so that the total of the VC peak speeds is equal to or higher than the VP capacity. There is a statistical multiplexing effect, and the effect is generally the number of accommodated VCs (the number of VP capacities divided by the VC peak speed) obtained when bandwidth allocation is performed without utilizing the burstiness of VCs.
And the ratio of the number of accommodated VCs that can be accommodated by utilizing the VC burst property. This ATM statistical multiplexing and QoS (Quality of Service)
e) is in a trade-off relationship. The larger the total VC peak speed is than the VP capacity, the more the VP capacity can be used without waste, but as the number of arriving cells increases, the VP capacity is exceeded. As a result, the cell loss rate increases and the QoS decreases. Further, as the total of the VC peak speeds is made smaller than the VP capacity, it is more difficult to exceed the VP capacity even when the number of arriving cells is increased, so that the QoS is improved, but the use of the VP capacity is inefficient. become. However, if the peak call speed and the average traffic are known in advance, it is possible to perform efficient band operation that satisfies the QoS target value.

Further, as a technique for improving the above-mentioned problem of the prior art that it is difficult to predict average traffic in advance and perform statistical multiplexing, bandwidth operation is performed based on the peak speed of a call source, which is relatively easy to predict. There is also a peak allocation method that does.

In addition, as a technique for improving the problem that the band use efficiency cannot be sufficiently increased when the peak allocation type call source has a strong burst property (the ratio of the average speed and the peak speed is small), the cell flow rate is improved. A method of observing and creating a frequency distribution of cell numbers, obtaining a cell loss probability by a predetermined evaluation formula based on the created frequency distribution, comparing it with a specified value, and making a VC acceptance decision based on the result Proposed (Saito et al., “Dynamic call admission control i
n ATM networks ”, IEEE J. Select. Areas Commun., Vol.
9 (No. 7), pp.982-989, Sept. 1991).

[0005]

However, in order to perform efficient band operation by the above-mentioned conventional technique of statistical multiplexing, it is necessary to know in advance the peak call rate and the average traffic, but the average There is a problem in that it is very difficult to predict proper traffic in advance.

Further, the above-mentioned conventional peak allocation method has a problem that the band operation efficiency cannot be sufficiently improved when the burstiness of each call source is strong.

Further, in the technique for improving the above-mentioned peak allocation method, in order to make a call admission decision, the distribution of the number of cells arriving within a window capable of admitting a certain number of cells is observed, and the result of observation is observed. Since it is necessary to perform statistical processing in real time, hardware resources such as a memory for storing the cell number distribution and a processor for performing statistical processing in real time are required, which raises a problem that the hardware cost increases.

The present invention has been made in view of the above points, and a call admission control method and a call admission control capable of performing admission control of a call without knowing the peak speed of the call and average traffic in advance. The purpose is to provide a device.

It is another object of the present invention to provide a call admission control method and a call admission control device capable of improving the band operation efficiency even when the burstiness of each call source is strong.

Further, there is provided a call admission control method and a call admission control device capable of calculating a cell flow rate and a cell loss rate with a simple algorithm and a small amount of hardware resources to satisfy a certain QoS target value. With the goal.

[0011]

FIG. 1 shows the principle of the present invention.

The call admission control method of the present invention is a method of performing admission control of a new call when a plurality of calls are multiplexed on a link having a definite capacity of an asynchronous transfer network, that is, when a call is admitted. In (1), the step of determining the load state of the link based on the difference between the number of cells arriving at the exchange in the asynchronous transfer network and the number of cells taken out from the buffer, and the duration of the difference (step 1); The step (step 2) of determining and controlling whether or not to accept a new call based on.

The above step 1 increments the value of the cell counter each time a cell arrives, decrements the value of the cell counter every time a cell is read from the buffer, and counts the number of cells. Determining whether the load state of the link is a heavy load state or a light load state, based on whether or not the value of is continuously a certain value or more for a predetermined time or more. .

The step 2 is a step of calculating the cell arrival rate in the determined load state based on the number of arriving cells in the determined load state and the duration of the determined load state, and the load state. The cell loss rate is calculated on the basis of the cell arrival rate and the average duration of the load state in the step of determining whether to accept a new call based on the calculated value, and a new step based on the determination result. Control of admission and rejection of various call admissions.

The method further comprises a step of calculating a cell arrival rate from which high frequency components of the cell arrival rate under the determined load state are removed.

Further, when the peak rate of the new call is known in advance, the method further comprises the step of correcting the cell arrival rate in the determined load state based on the peak rate of the new call.

Further, when the peak speed of the new call is known in advance, the method further comprises the step of correcting the cell arrival rate and the duration time in the light load condition among the determined load conditions based on the new peak speed of the call. .

FIG. 2 shows the principle configuration of the present invention.

The call admission control device 100 of the present invention is a device for performing admission control of a new call when a plurality of calls are multiplexed on a link of a definite capacity of the asynchronous transfer network 500, that is, when a call is admitted. Has the following means.

From the input / output means 110 for inputting / outputting cells to / from the asynchronous transfer network 500, the buffer means 120 for temporarily accumulating cells arriving via the input / output means 110, the number of arriving cells and the buffer means 120 A new call is controlled by controlling the load state determination unit 130 that determines the load state of the link based on the difference in the number of cells taken out and the duration of the difference, and the input / output unit 110 based on the determination result of the load state determination unit 130. And a call admission determination / control unit 140 that controls admission of the call.

The load state determining means 130 increments the value of the cell counter each time a cell arrives and decrements the value of the cell counter every time a cell is read from the buffer means 120 to count the number of cells. It has a cell counting means and a determining means for determining a heavy load state when the time during which the number of cells counted by the cell counting means continuously becomes a predetermined value or more is a predetermined time or more.

Further, the call acceptance judgment / control means 140
Is the number of cells arriving in the determined load state, and
Cell arrival rate calculation means for calculating the cell arrival rate in the load state determined based on the duration of the load state determined, and the cell loss rate calculated based on the cell arrival rate and the average duration of the load state Cell loss rate calculating means, a call acceptance determining means for determining whether or not to accept a new call based on the calculated cell loss rate, and a new call based on the determination result of the call acceptance determining means. It has call admission control means for controlling admission of admission and refusal of admission of a new call.

Further, it further comprises high frequency component removing means for calculating a cell arrival rate by removing high frequency components from the cell arrival rate under the determined load condition.

Further, when the peak speed of a new call is known in advance, there is provided first cell arrival rate modification means for modifying the cell arrival rate based on the peak speed of the new call.

Further, when the peak rate of the new call is known in advance, the cell arrival rate and the duration are further modified based on the peak rate of the new call.

The high frequency component removing means uses a low pass filter.

[0027]

The call admission control method and the call admission control device of the present invention use the MMPP (Markov Modulated P) in which the cell flow has two states, a light load state and a heavy load state.
Oisson Process) is used to model the observation information to be stored in two states: light load state and heavy load state.
It is possible to limit the parameters to the cell arrival rate in one state and the reciprocal of the average duration, and to derive them by simple arithmetic operations.

Further, by removing the high frequency component from the cell arrival rate in each state, it is possible to obtain a stable cell arrival rate in which the influence of cells that have arrived in the past is gradually suppressed, and stable arrival is achieved. It is possible to perform highly accurate call admission control based on the rate.

When the peak speed of a new call is known in advance, the cell loss rate after accepting the new call is estimated based on the known peak speed to estimate the MMP.
By correcting the value of the parameter P, it becomes possible to perform efficient call admission control.

[0030]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 3 shows a block diagram of the first embodiment of the present invention. The call admission control device 100 shown in the figure includes an input / output unit 110, a buffer 120, a load state determination unit 130, and a call admission determination / control unit 140.

The input / output unit 110 makes a plurality of calls (V) to the link (VP) of the deterministic capacity of the asynchronous transfer network 500.
C) is an input / output unit capable of accepting cells, exchanging cells with the asynchronous transfer network 500 and the buffer 120, and receiving from the asynchronous transfer network 500 based on an instruction from the call acceptance determination / control unit 140. Refuse to accept new calls.

The buffer 120 temporarily stores cells input from the asynchronous transfer network 500 via the input / output unit 110.

The load state judging section 130 comprises a cell counting section 131 and a judging section 132.

The cell counting unit 131 is used for the asynchronous transfer network 5
00, the number of cells input (arriving) to the input / output unit 110, and the input / output unit 11 extracted from the buffer 120.
The number of cells output from 0 to the asynchronous transfer network 500 is counted, and the time during which the difference between the number of arriving cells and the number of cells retrieved from the buffer 120 continues is counted.

The determination unit 132 determines whether the load state of the link of the input / output unit 110 is the light load state or the heavy load state based on the determination result of the cell counting unit 131. The definition of each load state will be described below with reference to the drawings.
FIG. 4 is a diagram showing definitions of a heavy load state and a light load state according to the embodiment of the present invention. As shown in the figure, when the transmission band of the cell transmitted from each call source exceeds the VP capacity, the heavy load state is set, and when the transmission band of the cell transmitted from each call source is below the VP capacity, the light load state is set. It is defined as the load state.

The call admission judgment / control section 140 is composed of a cell arrival rate calculation section 141, a cell loss rate calculation section 142, a call admission judgment section 143, and a call admission control section 144.

The cell arrival rate calculation unit 141 includes a determination unit 132.
The cell loss rate calculation unit 14 calculates the cell arrival rate λ in the determined load state and the reciprocal σ of the average duration of the load state.
Output to 2.

Below, the cell arrival rate λ in the case of a heavy load state
shows the _high and formula of the inverse sigma _high average duration of the load condition.

Λ _high = X _high / T _high σ _high = N _high / T _high X _high : Observation value of the number of arrivals of cells in a heavy load state T _high : Observation value of the total duration of the heavy load state N _high : Observation value of the number of state transitions to the heavy load state The calculation formulas for the cell arrival rate λ _{low in} the case of the light load state and the reciprocal σ _low of the average duration of the load state are shown below.

Λ _low = X _low / T _low σ _low = N _low / T _low X _low : observed value of the number of arrivals of cells in the light load state T _low : observed value of the total duration of the light load state N _low : Observation value of the number of state transitions to the light load state The cell loss rate calculation unit 142 calculates the queue model of MMPP / D / 1 / K based on the cell arrival rates λ and σ calculated by the cell arrival rate calculation unit 141. To calculate the cell loss ratio (CLR).

The call admission judgment unit 143 determines that the cell loss ratio (CLR) calculated by the cell loss ratio calculation unit 142 and the preset QoS target value of the cell loss ratio are: QoS target value of cell loss ratio ≧ cell loss If the relationship of the rate CLR is satisfied, it is determined that the new call is accepted, and if the relationship of the above is not satisfied, it is determined that the new call is not accepted.

If the result of the call acceptance determination unit 143 is that the new call is not accepted, the call acceptance determination / control unit 144 instructs the input / output unit 110 to reject the acceptance of the new call. .

The operation of the first embodiment of the present invention will be described below with reference to the drawings. FIG. 4 is a flowchart showing the operation of the first embodiment of the present invention.

(Step 10) Cell counting unit 131
Monitors the flow rates of the cells input (arriving) from the asynchronous transfer network 500 to the input / output unit 110 and the cells taken out from the buffer 120 and processed, and the determination unit 132 determines based on the monitoring result of the cell counting unit 131. The load status of the link of the input / output unit 110 is determined. Further, the cell arrival rate calculation unit 141 calculates the cell arrival rate in the load state determined by the determination unit 132. Detailed processing of this step 10 will be described later.

(Step 11) Cell loss rate calculation unit 142
Is the traffic theory based MMPP / based on the parameters of the MMPP estimated in step 10 above.
Cell loss ratio (CL
R) is calculated.

(Step 12) Call acceptance determination unit 14
3 compares the cell loss rate (CLR) calculated by the cell loss rate calculating unit 142 in step 11 with the QoS target value of the cell loss rate, and accepts a new call based on the comparison result. Whether or not to perform is determined. Further, the call admission control unit 144 instructs the input / output unit 110 whether to accept the new call or reject the new call based on the determination result of the call admission determination unit 143. Perform acceptance control. Details of step 12 will be described later.

The detailed operation of step 10 will be described below with reference to the drawings. FIG. 6 is a flow chart showing the operation of step 10 of the first exemplary embodiment of the present invention. In the following description, a virtual queue is used to count the difference between the number of cells input from the asynchronous transfer network 500 to the input / output unit 110 and the number of cells retrieved from the buffer 120. Also, the number of cells counted by the virtual queue is expressed as a queue length. That is, when the queue length of the virtual queue is 1, and when one cell further arrives and the queue length of the virtual queue is incremented, the queue length of the virtual queue becomes 2.

(Step 100) Cell counting unit 13
1 monitors the input / output unit 110 to determine whether or not a cell has arrived. If the cell has not arrived, step 1
Move to 2.

(Step 101) Cell counting unit 13
1 means that when the cell arrives at the above step 101,
The queue length of the virtual queue is incremented for one cell that has arrived.

(Step 102) Cell counting unit 13
1 determines whether or not the cell is taken out from the buffer 120, and if not, the process proceeds to step 104.

(Step 103) Cell counting unit 13
1 decrements the queue length of the virtual queue for one cell taken out from the buffer 120 when the cell is taken out from the buffer 120 in the above step 102.

(Step 104) The determination unit 132 determines whether the time during which the queue length of the virtual queue is continuously 1 or more exceeds a preset threshold value w (hereinafter referred to as window length w). If it is determined that the window length w is not exceeded, the process proceeds to step 106.

(Step 105) The judging section 132
At step 104, the queue length of the virtual queue is continuously 1
The above time is the preset window length
If w is exceeded, it is determined that the load is heavy, and then
Cell arrival rate calculation unit 141 is the arrival rate of cells under heavy load
λ_highAnd the reciprocal σ of the average duration under heavy load
_high, Number of transitions N from light load state to heavy load state_highetc
Is calculated and the process proceeds to step 108.

(Step 106) The determination unit 132 determines that the time from the queue length of the virtual queue being 0 and the queue length of the virtual queue being 1 or more to returning to 0 exceeds the preset window length w. If the queue length of the virtual queue is 0, and the time from when the queue length of the virtual queue becomes 1 or more to when it returns to 0 does not exceed the preset window length w. Otherwise, the process proceeds to step 108.

(Step 107) The determination unit 132 determines that the vehicle is in the light load state, calculates the number N of transitions to the light load state, and determines the determination result and the observation data (cell arrival number X, light load state (The duration T, the number of state transitions N to the light load state, etc.) are output to the cell arrival rate calculation unit 141, and the cell arrival rate calculation unit 141 outputs the cell arrival rate λ _low in the light load state, which is a parameter of the MMPP. Also, calculate the reciprocal σ _low of the average duration in the light load state.

(Step 108) The input / output unit 110
It is determined whether or not a new call has occurred. If no new call has occurred, the process proceeds to step 100, and if a new call has occurred, the process ends and the process proceeds to step 11. .

FIG. 7 is a flow chart showing the operation of step 12 of the first embodiment of the present invention.

(Step 120) Call acceptance determination unit 1
43 is a comparison of the cell loss rate CLR obtained by analyzing the MMPP / D / 1 / K queuing model in step 11 and the preset QoS target value of the cell loss rate, and the cell loss QoS target value ≧ cell loss rate CLR is established, it is determined that a new call is accepted, and if not established, it is determined that a new call is not accepted and the process proceeds to step 122.

(Step 121) Call acceptance control unit 1
44. In step 120, when the relationship of the QoS target value of the cell loss ratio ≧ the cell loss ratio CLR is established, it is possible to accept a new call, so that the acceptance of the new call is permitted. The input / output unit 110 is instructed to end the processing.

(Step 122) Call acceptance controller 1
If the relationship of the QoS target value of the cell loss ratio ≧ the cell loss ratio CLR is not established in the above step 120, 44 refuses to accept the new call because the new call cannot be accepted. The input / output unit 110 is instructed to end the processing.

A specific example of the first embodiment of the present invention will be described below. In the following specific example, it is assumed that the arrival status of cells, the queue length of the virtual queue, and the like are as shown in FIG. In the figure, the time when the queue length of the virtual queue is continuously 1 or more is w (= 6).
The criterion for the heavy load condition is that the time is equal to or longer than the cell time. The queue length of the virtual queue at the start is set to 0, and an example is shown in which no new call is generated between time 0 and time 18.

When the cell counting unit 131 starts observation at time 0, one cell arrives at time 2 (step 1
00, YES), the queue length of the virtual queue is incremented (step 101), but at the moment of time 2, since no cell has been taken out from the buffer 120 yet, decrementing is not performed (step 102, NO).

The determination unit 132 determines that the time during which the queue length of the virtual queue is continuously 1 or more at time 2 is 0 and does not exceed the preset window length w (= 6) (step 104, No), and since the queue length of the virtual queue has not returned to 0 after becoming 1 or more, the determination of the current load state is not performed (step 106, N).
O). Since no new call has been made, step 1
00 (step 108, NO).

Since two cells arrive at time 3 (step 100, YES), the cell counting unit 131 increments the queue length of the virtual queue by 2 to 3 (step 101). Further, the cell counting unit 131 has decremented the queue length of the virtual queue to 2 (step 103) because one cell has been taken out from the buffer 120 by time 3 (step 102, YES).

The determination unit 132 determines that the time during which the queue length of the virtual queue is continuously 1 or more is 1 and does not exceed the preset window length w (= 6) (step 1
04, NO), and since the queue length of the virtual queue has not returned to 0 after becoming 1 or more, determination of the current load state is not made (step 106, NO). Further, since no new call is generated, the process proceeds to step 100 (step 108, NO).

Since one cell has arrived at time 4 (step 100, YES), the cell counting unit 131 increments the queue length of the virtual queue to 3 (step 1).
01). Since one cell has been taken out from the buffer 120 by time 4 (step 102, YES), the queue length of the virtual queue is decremented to 2 (step 103).

The determination unit 132 determines that the time during which the queue length of the virtual queue is continuously 1 or more is 2 and does not exceed the preset window length w (= 6) (step 1
04, NO), and since the queue length of the virtual queue has not returned to 0 after becoming 1 or more, determination of the current load state is not made (step 106, NO). Further, since no new call is generated, the process proceeds to step 100 (step 108, NO).

Since the cell count unit 131 has not arrived at time 5 (step 100, NO) and one cell has been taken out from the buffer 120 by time 5 (step 102, YES), the virtual queue The queue length is decremented to 1 (step 103).

The determination unit 132 determines that the time during which the queue length of the virtual queue is continuously 1 or more is 3 and does not exceed the preset window length w (= 6) (step 1
04, NO), and since the queue length of the virtual queue has not returned to 0 after becoming 1 or more, determination of the current load state is not made (step 106, NO). Further, since no new call is generated, the process proceeds to step 100 (step 108, NO).

Since the cell count unit 131 has not arrived at time 6 (step 100, NO) and one cell has been taken out from the buffer 120 by time 6 (step 102, YES), the virtual queue The queue length is decremented to 0 (step 103). Judgment unit 1
32 is 4 when the queue length of the virtual queue is continuously 1 or more, and the preset window length w
(= 6) is not exceeded (step 104, NO), and the time from when the queue length of the virtual queue becomes 1 or more until it returns to 0 is 4 and the preset window length w
Since (= 6) is not exceeded (step 106, YES), it is determined that the light load state is from time 0 to time 6, the number N of transitions to the light load state is calculated, and the determination result and the observation data are obtained. (Cell arrival number X _low = 4, light load state duration T _low = 8, number of state transitions to light load state N _low = 1) is output to the cell arrival rate calculation unit 141,
Cell arrival rate λ _low in the light load state, which is a parameter of MMPP, and reciprocal σ of the average duration in the light load state
_Low is calculated (step 107). Further, since no new call is generated, the process proceeds to step 100 (step 108, NO).

Thereafter, the above steps 100 to 1
By repeatedly executing 08, it is determined whether the load state of the link of the definite capacity of the input / output unit 110 is the light load state or the heavy load state, and the MMPP
The parameters (λ, σ) can be calculated.

In the example of FIG. 8, next two cells arrive at time 9 and the queue length of the virtual queue becomes 1 or more again. It is at time 18 that the queue length of the virtual queue becomes 0 again. In this case, since the time during which the queue length of the virtual queue is continuously 1 or more exceeds the window length w (= 6), the time from time 9 to time 18 is reached. The period up to is considered to be heavily loaded.

In the present embodiment, the end time of the heavy load state is the later time of the time when the queue length of the virtual queue begins to monotonically decrease and the time after w hours from the start of the heavy load state. In the example of the figure, the time when the queue length of the virtual queue becomes 0 is time 18, but the time when the queue length of the virtual queue starts to decrease monotonically is time 16 and the start time of the heavy load state. Since it is 15 after w (= 6) cell time from time 9, it is assumed that the later time is selected and the end time of the heavy load state is time 16.

Below, the preset cell loss rate Qo
The S target value is 1.0 × 10 ^−6, and the cell loss ratio (CLR) obtained by the analysis of the MMPP / D / 1 / K queuing model is 1.2 × 10 ^−6. The operation of call acceptance determination and call acceptance control will be described.

When a new call is made to the input / output unit 110 during the repeated execution of the above steps 100 to 108 (step 108, YES), the cell loss rate calculation unit 142 causes the cell loss rate calculation unit 142 to perform the above step 107. M calculated by
Based on the MPP parameters, the MMPP / D / 1 / K queuing model based on the traffic theory is analyzed to calculate the cell loss rate (CLR) CLR = 1.2 × 10 ⁻⁶ (step 11).

The call admission judgment unit 143 determines the cell loss ratio (CLR) obtained by analyzing the MMPP / D / 1 / K queuing model in step 11 and the QoS of the preset cell loss ratio. Comparing with the target value, the relationship of QoS target value of cell loss ratio ≧ cell loss ratio CLR is not established (1.0 × 10 ⁻⁶ ≦ 1.2
^{X10 -6} ), it is determined that the new call is not accepted (step 120, NO), the input / output unit 110 is instructed to reject the new call, and the call acceptance is controlled (step 10). 122).

According to the above embodiment, the following effects can be obtained. Below, the band use efficiency obtained by the first embodiment will be described using a numerical example that evaluates the case of multiplexing a plurality of call types having different traffic characteristics (the case of accepting a plurality of calls). After that, call type i
Will be described using the following symbols.

N _i : Number of VCs to be multiplexed (number of calls accepted) B _i : Average burst length sent from VC R _i : Peak sending speed of VC at a special sending speed at which VC sends bursts p _i : Ratio of average speed to VC peak speed In general, it is difficult to predict B _i when setting VC.
Also, p _i is equal to the percentage of time that the VC is sending bursts. In addition, it is generally difficult to predict p _i when setting VC.

FIG. 9 is a diagram showing the band use efficiency of the first embodiment of the present invention. Bandwidth efficiency is the cell loss rate Qo
It is calculated from the maximum number of call connections that can be considered to satisfy the S target value. The ideal scheme in Figure 9 is
It corresponds to the maximum number of connections obtained by evaluating the cell loss rate in advance with the average cell speed and average burst length of each call known. In practice, it is difficult to estimate the average cell rate and average burst length of each call before connection, and the present invention can estimate the average cell rate and average burst length of each such call before connection. This makes it possible to perform call admission control in a difficult case.

The graph described as the proposed system in FIG. 9 corresponds to the maximum number of connections obtained based on the cell loss rate obtained by the call admission control device 100 according to the first embodiment of the present invention.
In the figure, the QoS objective of the cell loss rate is set to 10 ^-6, and VP is set.
The band is 150 Mb / s and the buffer length is 20 cells. In the evaluation model of this time with p _i = 0.1, the bandwidth management method for peak allocation can improve the bandwidth efficiency up to 0.1, but in the ideal method, it is about 3 to 5 times that of the peak allocation method. It can be seen that the bandwidth usage efficiency is more than doubled. Further, it can be seen that in the proposed system, which is the device 100 of the first embodiment of the present invention, the higher the window length w, the higher the band use efficiency can be obtained. For example, N ₁ : N _{2 in} (1) of FIG. 9 which is a unit environment
In the case of = 10: 0, the band use efficiency is rapidly improved after w has passed 25 cells, which is the reciprocal of the peak speed of the call type 1 (high speed), and an efficiency close to that of the ideal system is obtained.

Further, the relationship between the mixed ratio of a plurality of call types and the optimum window length w can be understood from the changing states of the graphs (1), (2) and (3) in FIG. . The critical value of w at which the band use efficiency starts to increase increases as the mixing ratio of the call type 2 (low speed) increases, and approaches the reciprocal of the peak speed of the call type 2 (100 cells). That is, even if a plurality of call types are mixed, if the peak speed of each call type is 1.5 Mb / s or more (the VP band is 150 Mb
/ S), the window length w is 100 cells (1.5 Mb
/ S), the call admission control device 1 of the present invention
According to the proposed method of the first example of No. 00, it is possible to obtain an ideal band use efficiency.

Further, when the peak speed is lower than 1.5 Mb / s, it is estimated that the window length w needs to be increased to 100 cells or more. Traffic fluctuations tend to have a smaller effect on the overall QoS, and the observation window length w is excluded by excluding low-speed call sources that do not affect the overall QoS.
Should be decided.

The second embodiment of the present invention will be described below. FIG. 10 is a configuration diagram of the second embodiment of the present invention.
The call admission control device 100 shown in the figure has the same configuration as that of the first embodiment shown in FIG.
And the cell loss rate calculation unit 142 between the high frequency component removal unit 145.
Is provided.

When the cell arrival rate λ and the reciprocal σ of the average duration calculated by the cell arrival rate calculator 141 are input, the high frequency component removing section 145 receives the high frequency from the cell arrival rate λ and the reciprocal σ of the average duration. The cell arrival rate λ from which the components are removed and the high frequency components are removed and the reciprocal σ of the average duration are output to the cell loss rate calculation unit 142.

The flowchart showing the operation of the second embodiment is basically the same as that shown in FIGS. 5, 6 and 7, but FIG.
The calculation formulas for the cell arrival rate λ _high and the reciprocal σ _high of the average duration in step 105 are as follows: <In case of heavy load> λ _high (t + 1) = αa (t + 1) + (1-α) λ _high
(T) σ _high (t + 1) ⁻¹ = β (t−τ _h ) + (1−β) σ
_high (τ _h ) ^-1 <in light load state> λ _high (t + 1) = λ _high (t) σ _high (t + 1) ^-1 = σ _high (τ _h ) ^-1 a (t + 1) at time t + 1 Τ _h, which indicates the number of arriving cells, is replaced with the latest transition time from the heavy load state to the light load state.

Further, each calculation formula of the cell arrival rate λ _low and the reciprocal σ _{lo w} of the average duration in step 107 of FIG. 6 is calculated as _follows : <In the case of heavy load> λ _low (t + 1) = λ _low (t) σ _low (t + 1) ^-1 = σ _low (τ _l ) ^-1 <in the case of light load> λ _low (t + 1) = αa (t) + (1-α) λ
_low (t) σ _low (t + 1) ⁻¹ = β (t−τ _l ) + (1-β) σ
_low (τ _l ) ^-1 where τ _l indicates the latest transition time from the light load state to the heavy load state, where a (t + 1) is replaced with the number of arriving cells at time t + 1.

In the first embodiment, since all the data after the time when the observation is started are treated with the same weight,
As the observation time elapses, tracking of traffic fluctuations worsens. For this reason, in the second embodiment, the fact that the tracking of the traffic fluctuation becomes worse as the observation time of the first embodiment elapses is improved by providing the high frequency component removing unit 145 shown in the above calculation formula. (The high-frequency component removing unit 145 is realized by using a first-order low-pass filter).

The coefficient α in the above equation is the current observation a
The weight of (t + 1) is shown, and the larger this value, the more it becomes possible to follow micro traffic fluctuations. On the contrary, if the value of α is reduced, the microscopic fluctuation of traffic will be eliminated. That is, this coefficient α
Is for controlling the high frequency component area removed by the high frequency component removing unit 145. If the number of calls to be multiplexed (the number of calls accepted) is constant, each parameter of the MMPP is constant, so the coefficient α is determined so as to remove the frequency component that fluctuates within the time scale of the fluctuation of the number of calls. do it.

Further, regarding the coefficient β in the above calculation formula, α
Similar to the above, it may be determined so as to remove the frequency component that fluctuates within the time scale of the fluctuation of the number of calls.

Next, a third embodiment of the present invention will be described.
FIG. 11 is a block diagram of the third embodiment of the present invention. The call admission control device 100 shown in FIG.
The configuration is such that the first cell arrival rate correction unit 146 is provided between the cell arrival rate calculation unit 141 and the cell loss rate calculation unit 142 of the configuration of this embodiment. The third embodiment is a two-state MMPP based on the peak speed if the VC peak speed is known.
By correcting the cell arrival rate in each of the heavy load state and the light load state, the cell loss rate after the VC is accepted (after the call is accepted) is estimated.

The first cell arrival rate correction unit 146 uses the VC
When the peak speed of (call) is known in advance, the cell arrival rate λ of the cell arrival rate λ and the reciprocal σ of the average duration input from the cell arrival rate calculation unit 141 is based on the VC peak rate. And the reciprocal σ of the average continuation time input from the cell arrival rate calculation unit 141.
Is output to the cell loss rate calculation unit 142 and the call reception control unit 144 receives the call,
The MMPP parameter calculated by the cell arrival rate calculation unit 141 before accepting the call is used as the first cell arrival rate correction unit 1
Replace with the value modified in 46.

The flowchart showing the operation of the third embodiment is basically the same as that shown in FIGS. 5, 6 and 7, but FIG.
The following processing is performed between steps 10 and 11 shown in FIG. The symbols used in the calculation formula are explained below. The parameters of MMPP before the acceptance of VC are: cell arrival rate in heavy load state λ _high cell arrival rate in light load state λ _low reciprocal of average duration of heavy load state σ _high average duration of light load state The reciprocal σ _low, and the parameter of MMPP after receiving the VC of peak speed R is the cell arrival rate in a heavy load state λ _high ⁺ the cell arrival rate in a light load state λ _loW ⁺ the average duration of the heavy load state Reciprocal σ _high ⁺ reciprocal of average duration of light load condition σ _low ⁺ . Also, let VP band be C.

Between steps 10 and 11, the following calculation is carried out: λ _high ⁺ = λ _high + R / C λ _loW ⁺ = λ _loW + R / C σ _high ⁺ = σ _high σ _low ⁺ = σ _low Is output to the cell loss rate calculation unit 142.

If the acceptance of a new call (VC) is permitted in step 121 of FIG. 7, step 12
Subsequent to 1, a process of replacing the value of the MMPP parameter calculated in step 105 or step 107 with the value calculated between step 10 and step 11 is performed.

Next, a fourth embodiment of the present invention will be described.
FIG. 12 is a configuration diagram of the fourth embodiment of the present invention. The call admission control device 100 shown in FIG.
The second cell arrival rate correction section 147 is provided between the cell arrival rate calculation section 141 and the cell loss rate calculation section 142 of the configuration of the above embodiment.

The second cell arrival rate correction unit 147
When the peak speed of (call) is known in advance, the cell arrival rate λ in the light load state and the reciprocal σ of the average duration input from the cell arrival rate calculation unit 141 are based on the VC peak speed. If the call acceptance control unit 144 accepts the call, the corrected cell arrival rate λ and the reciprocal σ of the average duration σ are output to the cell loss rate calculation unit 142. The MMPP parameter calculated by the cell arrival rate calculation unit 141 is replaced with the value corrected by the second cell arrival rate correction unit 147.

The flowchart showing the operation of the fourth embodiment is basically the same as that shown in FIGS. 5, 6 and 7, but FIG.
The following calculation processing is performed between steps 10 and 11 shown in FIG.

Ρ ⁺ = ρ + R / C λ _high ⁺ = λ _high λ _loW ⁺ = λ _loW + R / C σ _high ⁺ = σ _high σ _low ⁺ = ((ρ ⁺ −λ _loW ⁺ ) σ _high ⁺ ) / (λ _high
⁺ −ρ ⁺ ) The above ρ indicates the average cell arrival rate before the acceptance of a new call (VC), and is calculated by the following equation.

Ρ = (λ _high σ _high + λ _loW σ _low ) /
(Σ _low + σ _high ) In the above embodiment, the case where a plurality of VCs that perform bursty information transfer are multiplexed with a VP having a deterministic capacity has been described as an example, but a transmission line having a deterministic capacity is described. The present invention can also be applied to the case where a plurality of VPs that perform bursty information transfer are multiplexed, and bursty information transfer is performed for the VP having the deterministic capacity described in this embodiment. However, the present invention is not limited to the case of multiplexing a plurality of VCs for performing.

In the above embodiment, the heavy load condition is determined when the time during which the queue length of the virtual queue is continuously 1 or more exceeds the predetermined window length w, and the light load condition is determined. The determination was made assuming that the time from when the queue length of the virtual queue becomes 1 or more to when it returns to 0 does not exceed the predetermined window length w.
Therefore, even if the queue length of the virtual queue is 1 or more, if it does not return to 0, it is not judged as a light load state,
In some cases, it is determined that the light load state has been reached retroactively when the timing returns to 0. However, regarding the determination of the light load state, it is possible to determine all the states that are not determined to be the heavy load state as the light load state, and it is limited to the timing of the determination of the light load state and the heavy load state described in the above embodiment. It is not something that will be done.

[0102]

As described above, according to the present invention, the observation information to be stored in the two states can be stored by modeling the cell flow into the two states of the light load state and the heavy load state. It becomes possible to limit to the parameters of the cell arrival rate and the average duration of each state, and it becomes possible to judge and control whether or not to accept a new call by simple arithmetic operations. .

Further, due to the above effects, it is possible to perform call admission control with a small hardware resource and a simple observation algorithm without using expensive and complicated observation equipment or arithmetic unit, and to maintain a constant QoS.
It is possible to improve the band use efficiency of the communication network while satisfying the target value.

Further, with the above effect, it is possible to perform highly efficient band management as compared with the peak allocation method, and it is possible to estimate the average cell speed and the average burst length of each call before connection. It becomes possible to control admission of a new call.

Further, by removing the high frequency component from the cell arrival rate in each state of MMPP, it becomes possible to control the admission of a new call while following the micro fluctuation of the traffic and to control the traffic. It is also possible to eliminate microscopic fluctuations and perform new call admission control.

When the peak speed of a new call is known in advance, it is possible to perform highly accurate call admission control by correcting the parameter value of the MMPP based on the peak speed. Become.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a principle configuration diagram of the present invention.

FIG. 3 is a configuration diagram of a first embodiment of the present invention.

FIG. 4 is a diagram showing definitions of a heavy load state and a light load state in the embodiment of the present invention.

FIG. 5 is a flowchart showing the operation of the first exemplary embodiment of the present invention.

FIG. 6 is a flowchart showing an operation of step 10 of the first exemplary embodiment of the present invention.

FIG. 7 is a flowchart showing an operation of step 12 of the first exemplary embodiment of the present invention.

FIG. 8 is a diagram illustrating a specific example of the first embodiment of the present invention.

FIG. 9 is a diagram showing band use efficiency according to the first embodiment of this invention.

FIG. 10 is a configuration diagram of a second embodiment of the present invention.

FIG. 11 is a configuration diagram of a third embodiment of the present invention.

FIG. 12 is a configuration diagram of a fourth embodiment of the present invention.

[Explanation of symbols]

100 call admission control device 110 input / output unit, input / output unit 120 buffer unit, buffer 130 load state determination unit, load state determination unit 131 cell count unit 132 determination unit 140 call admission determination / control unit, call admission determination /
Control unit 141 Cell arrival rate calculation unit 142 Cell loss rate calculation unit 143 Call admission determination unit 144 Call admission control unit 145 High frequency component removal unit 146 First cell arrival rate correction unit 147 Second cell arrival rate correction unit 500 Asynchronous transfer network

Claims (13)

[Claims] 1. A call admission control method for performing admission control of a new call when a plurality of calls are admitted to a link having a definite capacity of an asynchronous transfer network, wherein a cell arriving at a switch in the asynchronous transfer network. The difference between the number of cells and the number of cells taken out from the buffer and the duration of the difference, and based on the result of the determination, whether to accept the new call is determined. A call admission control method comprising the steps of: 2. The step of determining the load state includes incrementing a value of a cell counter each time a cell arrives,
Counting the number of cells by decrementing the value of the cell counter each time a cell is read from the buffer, and whether the time when the value of the cell counter continuously exceeds a certain value is a predetermined time or more The call admission control method according to claim 1, further comprising a step of determining whether the load state of the link is a heavy load state or a light load state based on whether or not the link is present. 3. The step of determining and controlling whether or not to accept the new call, the step of controlling based on the number of arrival cells in the determined load state and the duration of the determined load state Calculating a cell arrival rate in the determined load state, calculating a cell loss rate based on the cell arrival rate in the load state and the average duration of the load state, based on the calculated value The call admission control according to claim 1 or 2, further comprising: a step of determining whether or not to admit the new call, and a step of controlling permission and refusal of admission of the new call based on the determination result. Method. 4. The call admission control method according to claim 3, further comprising the step of calculating a cell arrival rate from which high frequency components of the cell arrival rate under the determined load state are removed. 5. The method further comprising the step of modifying the cell arrival rate under the determined load condition based on the peak rate of the new call when the peak rate of the new call is known in advance. The call admission control method described in 3 or 4. 6. When the peak rate of the new call is known in advance, the cell arrival rate and the duration in the light load state among the determined load states are set to the peak rate of the new call. 5. The call admission control method according to claim 3, further comprising a step of correcting the call admission. 7. A call admission control device that performs admission control of a new call when a plurality of calls are admitted to a link having a definite capacity of an asynchronous transfer network, and performs input / output of a cell with the asynchronous transfer network. Input / output means, buffer means for temporarily accumulating cells arriving via the input / output means, based on the difference between the number of arriving cells and the number of cells taken out from the buffer means, and the duration of the difference A load state determining means for determining the load state of the link; and a call acceptance determining / controlling means for controlling the input / output means based on the determination result of the load state determining means to control acceptance of the new call. A call admission control device characterized by the above. 8. The load state determination means increments the value of the cell counter each time a cell arrives and decrements the value of the cell counter every time a cell is read from the buffer means to count the number of cells. 8. A cell counting means for controlling the number of cells, and a determining means for determining a heavy load state when a time during which the number of cells counted by the cell counting means continuously exceeds a predetermined value is a predetermined time or more. Call admission control device. 9. The call admission judgment / control means, wherein the number of cells arriving in the judged load state,
Cell arrival rate calculation means for calculating a cell arrival rate in the determined load state based on the determined load state duration, and a cell based on the cell arrival rate and the average duration of the load state Cell loss rate calculating means for calculating a loss rate, call acceptance determining means for determining whether or not to accept the new call based on the calculated cell loss rate, and a determination result of the call acceptance determining means 9. The call admission control device according to claim 7, further comprising call admission control means for controlling admission of the new call admission and rejection of the admission of the new call based on the above. 10. The call admission control device according to claim 9, further comprising high frequency component removing means for calculating a cell arrival rate obtained by removing a high frequency component from the cell arrival rate under the determined load state. 11. The first cell arrival rate correction means for correcting the cell arrival rate based on the peak rate of the new call when the peak rate of the new call is known in advance. The described call admission control device. 12. A second cell arrival rate modification means for modifying the cell arrival rate and the duration based on the peak rate of the new call when the peak rate of the new call is known in advance. The call admission control device according to claim 9 or 10. 13. The call admission control device according to claim 10, wherein the high-frequency component removing means uses a low-pass filter.