JP3529982B2 - Multi-traffic call admission control method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a new request that occurs in a communication system in which a plurality of users are allocated resources of the amount necessary for users to communicate from among resources shared by a plurality of users to communicate. The present invention relates to a call admission control method for multiple traffic that determines whether or not to admit.

[0002]

2. Description of the Related Art In a communication system such as a fixed telephone and a facsimile used in each home or office, or a mobile communication system such as a mobile telephone or a car telephone, generally, resources used by a plurality of users for communication are provided. Share.

For example, when considering a telephone in an office with 10 employees, the probability that all 10 employees will talk is very small, and it is considered to be almost zero. Therefore, the telephone line required for this office is required. The number can be smaller than 10 lines. They share a limited number of phones with each other, use the lines when needed, and then release the lines for other employees to use when they're done. However, sometimes a situation occurs in which all the lines are in use and cannot be called even though the user wants to make a call. When such a situation occurs, in many current communication systems, this new call request (call) results in a call loss. From the economical point of view, it is better to install as few lines as possible. However, if the amount is too small, a lot of call loss may occur, which may increase employee dissatisfaction or may prevent the work from progressing smoothly. In order to meet such conflicting requirements, the Erlang B formula (Fujiki, Kanbe, "Communication Traffic Theory", Maruzen, 1980) is usually used.
Is used to design the number of lines such that the call loss rate is a sufficiently small value, for example, 1% to 3%.

Such a situation can be considered in the same manner in a fixed telephone communication system other than the office or a mobile communication system. In particular, in a mobile communication system, communication between a base station and a mobile station is established by wireless transmission, and a resource used for communication is a wireless channel. In mobile communication systems, the frequency band that can be used is generally limited, so the problem of resource sharing can be a more serious problem than in fixed telephone networks that use wired lines for their information transmission.

Further, in recent years, the amount of resources used for one communication has been the same in the conventional communication system due to diversification of user's requests and development of transmission technology. , The amount of resources used is different for each communication. For example, ISDN (Integrated Services Digital Network) that handles various services in an integrated manner.
ork) is based on a transmission rate of 64 kbit / s, and services higher transmission rates such as 128 kbit / s and 384 kbit / s. More network resources are required for higher speed information transmission. In addition, in a PDC (Personal Digital Cellular) system, which has become a domestic standard for mobile / car phone systems, a TDMA (Time Division Multiplexer) that divides one frequency into six channels (time slots) is used.
Access) method is used. In the initial stage of the PDC system, the voice call service was provided by the full rate system in which voice was transmitted using two of the six channels. After that, with the development of voice coding technology, voice can be transmitted only by using one channel (half rate system). Therefore, in the current digital portable / car phone system, a voice call by the full rate method using 2 channels and a voice call by the half rate method using 1 channel are mixed among these 6 divided channels. There is.

As described above, in recent communication systems, due to changes in communication requirements or developments in transmission technology,
The resources required for each communication are different. When calls that require different resources coexist, comparing the call loss rates for each call type makes the call loss rates for each call type unfair, and the call loss rates for calls that require more resources become very large. There is a serious problem that is not desirable for practical use. For example, consider a case where a call type 1 (called a narrow band call) that requires one channel for communication and a call type 2 (called a wide band call) that requires 10 channels coexist. Since the call type 2 requires 10 channels, it cannot be accepted unless there are 10 or more unused channels in the system. On the other hand, call type 1
Since only one channel is required for, the unused channel is accepted if there is even one channel. As is clear from this description, the larger the amount of resources required for communication, the more difficult it is to accept the call, and the call loss rate increases.

As described above, in order to solve the problem that the call loss ratio becomes unfair depending on the call type and the call loss ratio of the wideband call increases, some resources are reserved without being allocated to the narrowband call. There are a dedicated line system used exclusively for broadband calls, and a line reservation system that stops the reception of narrowband calls according to the number of lines in use and reserves the line for the wideband call. , Minoru Akiyama, "Modern Telecommunication Switching Engineering", Chapter 6). In the leased line system, for example, a narrow band call that requires one channel for communication,
Consider again a system with mixed broadband calls that requires 10 channels. Now, assume that there are 100 channels in total in this system. In the line reservation, for example, 20 lines among them are reserved exclusively for the wide band, and the remaining 80 lines are shared by the narrow band call and the wide band call. In this case, in the operation when a narrow band call occurs, if there is an unused channel among the shared 80 channels, it is accepted, and if not, a call loss occurs. In the operation when a broadband call occurs, if there are 10 or more unused channels out of the 80 shared channels, it is accepted, and if not, 20 channels dedicated to broadband are checked. If there are 10 or more unused channels out of 20 channels dedicated to wideband, the channel is accepted, and if not, a call loss occurs.

When the dedicated line system or the line reservation method is used, if the number of reserved lines is increased, the broadband call is prioritized, and the call loss rate of the broadband call is reduced. On the contrary, the loss rate of narrow band calls becomes large. Therefore, if the number of reserved lines is optimally determined, it is possible to make the call loss ratios of the wideband call and the narrowband call fair.

[0009]

In the above-mentioned conventional method, it is necessary to accurately grasp the applied call volumes of the wideband call and the narrowband call in order to optimize the number of reserved lines. Further, when the applied call volume changes, the call loss rate of a specific call type increases, or the resource utilization efficiency significantly decreases, so that there is a problem that redesign is necessary. In general, it is very difficult to accurately grasp the applied call volume, and since the situation fluctuates moment by moment, when the conventional line reservation method is actually applied,
There is a serious problem that the call loss rate cannot be kept fair.

The present invention has been made in view of the above,
The purpose is to be able to maintain a fair call loss rate for each call type and to effectively utilize limited resources, even if a plurality of call types having different amounts of resources required for communication are mixed. It is to provide a call admission control method for multiple traffic that can be performed.

[0011]

In order to achieve the above-mentioned object, the present invention according to claim 1 provides a resource required for a user to communicate from among resources shared by a plurality of users. A call admission control method for deciding whether or not to accept a new request that occurs in a communication system that is assigned and communicates, and calculates and shares the total amount of resources currently used for communication. All
The maximum resource one communication needs from the amount of sources
Is determined as the threshold for call acceptance.
The total amount of the resources calculated and determined
The total amount of the resource is compared with the threshold value
If it exceeds the
Use as a summary .

According to the first aspect of the present invention, whether or not to accept a newly generated call is not currently used in the communication system regardless of the amount of resources required by the originated call. Since the total amount of resources is compared with a predetermined threshold value, even if there are a plurality of types of calls with different required amounts of resources, the call loss ratio can always be kept fair.

[0013]

In the present invention according to claim 1, the predetermined threshold value for call reception is determined as a value obtained by subtracting the maximum resource amount required for one communication from the total resource amount. Therefore, all resources available in the entire system can be effectively used. Main claim according to claim 2
Ming accepted the communication in the invention according to claim 1.
Call declared peak rate, average transmission rate or minimum guaranteed transmission rate
Calculate the total amount of degrees and declare from the amount of shared resources
The value obtained by subtracting the maximum transmission rate that may
Declaration peak calculated and determined as a threshold for
Determined as total amount of speed, average transmission speed or minimum guaranteed transmission speed
Compared to the threshold for admitted call admission,
If the threshold is exceeded, a new call is judged as a call loss
The point is to do. The present invention according to claim 3 claims
In the invention described in the paragraph 1, currently used for communication
Frequency of shared power by calculating the total power of interfering waves
Make a new call from the maximum allowable interference power in the band
Subtract the maximum value of the interference wave power that increases when it is accepted
The calculated value is determined and used as the threshold for call acceptance.
The total power value of the generated interference wave and the determined call acceptance
The threshold value is compared and the sum exceeds the threshold value.
If a new call is lost, the point is to judge that it is a call loss.
It

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram schematically showing resources used in a communication system to which a call admission control method for multiple traffic according to an embodiment of the present invention is applied.
The direction of the arrow indicates the direction in which the number of resources is large. The figure shows a case where the total number of resources is 200. The shaded area in the figure indicates the number of resources currently in use. In FIG. 1, the number of resources currently in use is 184. In FIG. 1 and the following description, as symbols, the total number N of resources, the number C of resources currently in use, the call admission threshold value T, the number J of call types, the applied call volume a _{i of} the call type i, and the call type i are shown. The number M _i of resources used for communication is used.

Next, the operation of this embodiment will be described with reference to the flowchart shown in FIG. When the call admission control method of this embodiment starts operation, it initializes a threshold value T for call admission to a value obtained by subtracting the maximum resource value M required for one communication from the total number of resources N, and The number C of resources in use is initialized to 0 (step S1). Next, it is confirmed whether there is a resource allocation request (step S
3) If there is a request, it is further checked whether the number C of resources currently in use exceeds a threshold value T (step S5). If the number C of resources currently in use exceeds the threshold value T, the call is treated as a call loss and the process returns to step S3 after initialization (step S7). If the number C of resources currently in use is less than or equal to the threshold T, the number C of resources currently in use is increased by the number of resources M _i used for communication by the call type, and resource allocation processing is performed. Return to step S3 after initialization (step S9,
S11).

If there is no resource allocation request in the determination of step S3, it is checked whether or not there is any one of the users who are currently in communication who has ended the call (step S13). If there is no one that has ended, the process returns to step S3 after initialization. If there is an ending story,
Resource release processing is performed in step S1, the number C of resources currently in use is reduced by M _i by the number of resources used by the call type for communication, and the process returns to step S3 after initialization (step S17).

Next, an example of the operation of the call admission control method of this embodiment will be described with reference to an example. The call admission control method of the present embodiment shown by the flowchart of FIG. 2 operates in exactly the same way regardless of the number of call types, two or more. Therefore, in the following description, the number of call types will be simplified for simplicity. Will be described as an example. In the following, the total number of channels N = 2
00, one wideband call uses 16 channels for a narrowband call. Given 20
Considering the case where the 0 channel is used most effectively, the threshold value T is set to T = 200-16 = 184.

FIG. 3A shows the case where the total sum of the channels currently in use is C = 184, that is, equal to the threshold value. At this time, when a narrow band call occurs, it is accepted, and the state shifts to the state of the number of used channels 185 as shown in FIG. Also, when a wideband call occurs, the number is accepted and the number of channels in use C = 2 as shown in FIG.
The state moves to 00. In this way, if C does not exceed T (C ≦ T), both the narrow band call and the wide band call can be accepted.

On the other hand, consider a case where the number of channels in use is C = 185 and the threshold T is exceeded by 1 as shown in FIG. 4 (a). Since C> T in both cases where a wideband call and a narrowband call occur, the call cannot be accepted. For a wideband call, the number of remaining channels is less than the required number of channels 16, which naturally causes a call loss.
For narrow band calls, there is a call loss despite the presence of unused channels. That is, it can be considered that these 15 channels are reserved for the broadband call. The call admission method of the present embodiment is largely different from the conventional line reservation method. According to the call admission method, the call admission can be accepted only by the total number of channels currently in use, regardless of the call type of the generated call. Since the decision is made, the average call loss rate for each call type is always the same.

Next, the effect of equalizing the call loss rates is confirmed by computer simulation. Total number of channels N = 2
00 and then, applied traffic intensity narrowband call a ₁ [Erlangs], broadband call a ₂ [Erlangs], also the number of used channels narrowband call 1, the broadband call shall be 16 channels used. The simulation was performed with the total call volume (a ₁ + a ₂ ) as a parameter in the following two cases, and the call loss rate characteristics were evaluated.

(1) Case 1: Call volume ratio is narrowband call: wideband call = 10: 1 (2) Case 2: Call volume ratio is narrowband call: wideband call = 20: 1 Simulation Results are shown in FIG. In each case, it can be seen that the call loss rates of the narrowband call and the wideband call are equal regardless of the applied call volume and are fair.

In this embodiment, when a line (channel) having a certain transmission capacity exists as the minimum unit of resources, that is, the amount of resources required for communication, the total amount of shared resources, etc. Has been described in the case where all are represented by integers. This is, for example, NI
Basically, a line having a transmission capacity of 64 kbit / s in SDN is used as a unit when a higher transmission speed is realized by bundling multiple lines and when the transmission line is divided in time. It corresponds to the case where different transmission rates are realized depending on the number of time slots allocated per hour. However, this does not limit the application of the present invention. For example, ATM (Asyncronous Transfer Mode) used as a transmission technology of B-ISDN
Then, at the time of establishing the connection, the traffic characteristics of the own terminal are represented by the average transmission rate, the peak transmission rate, the minimum guaranteed transmission rate, etc., and notified to the network. The network determines whether or not to accept the connection based on the declared traffic characteristics. Even in such a case, the present invention is applied to set the threshold T by the maximum transmission rate M that may be declared as the total amount of shared resources (total transmission rate) N for which call admission should be determined. The same effect can be obtained by setting and determining the call acceptance based on this setting. However, the total amount C of resources used for communication is calculated by comparing with the threshold value, and the sum of the declared peak rate or average transmission rate, minimum guaranteed transmission rate, etc., of the calls accepted for communication is simply calculated. However, it may be an amount that allows for the statistical multiple-effect characteristic supported by a simulation or the like.

Furthermore, code division multiple access (Code Division
In a mobile communication system that performs communication between a base station and a mobile station using multiple access (CDMA), the amount of resources should be replaced with the power value of an interference wave in the uplink (transmission by the mobile station, reception by the base station), for example. You can Therefore,
By applying the present invention, based on the maximum value of the interference wave power allowed in the shared frequency band for which the call acceptance should be determined, and the maximum value of the interference wave power increased when a new call is accepted The same effect can be obtained by setting a threshold value and determining call acceptance based on this. in this way,
The present invention can be applied to the case where the resource amount is not represented by an integer, and the same effect can be obtained.

[0026]

As described above, according to the present invention,
Whether or not to accept a newly generated call is not based on the amount of resources required by the originated call, but only based on the total amount of resources currently used in the communication system. Even if there are multiple types of calls with different amounts, the call loss rate can always be kept fair, and even if the call volume and ratio for each call type change, there is no need to redesign as in the past. is there.

Further, according to the present invention, the predetermined threshold value for call reception is determined as a value obtained by subtracting the maximum resource amount required for one communication from the total resource amount. It is possible to use the given resources as effectively as possible while always maintaining fair call loss ratios of multiple call types.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing resources used in a communication system to which a call admission control method for multiple traffic according to an embodiment of the present invention is applied.

FIG. 2 is a flowchart showing the operation of the call admission control method of this embodiment.

FIG. 3 is a diagram for explaining the operation of the call admission control method of the present embodiment when admission is possible.

FIG. 4 is a diagram for explaining the operation of the call admission control method of the present embodiment in the case of admission rejection.

FIG. 5 is a graph showing a simulation result of a call loss rate characteristic of the present embodiment.

─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-2-214243 (JP, A) JP-A-10-13949 (JP, A) JP-A-4-127621 (JP, A) JP-A-9- 224284 (JP, A) JP-A-8-191481 (JP, A) Patent 2889936 (JP, B2) Patent 2905132 (JP, B2) Patent 3361722 (JP, B2) Ishikawa, et al. CDMA capacity design method, IEICE Technical Report, RCS95-132 (58) Fields investigated (Int.Cl. ⁷ , DB name) H04L 12/56 200

Claims (3)

(57) [Claims] 1. In a communication system in which a plurality of users are assigned resources of the amount necessary for the users to communicate among resources shared by a plurality of users, and whether or not to accept a new request that has occurred. Is a call admission control method for determining whether or not to calculate the total amount of resources currently used for communication.
For the call reception, a value obtained by subtracting the maximum resource amount required for one communication from the total amount of shared resources and the first step
The second step of determining the threshold value, the total amount of the resources calculated in the first step, and the second step .
By comparing the threshold determined in two steps, wherein the total amount of the resource and a third step of determining the call loss of a new call when it exceeds the threshold Call admission control method for multiple traffic. 2. Claimed peak speed of calls accepted for communication,
Calculate the total amount of average transmission rate or minimum guaranteed transmission rate
Four steps, The maximum amount that can be declared from the amount of resources shared
The value obtained by subtracting the large transmission rate is used as the threshold for call acceptance.
And a fifth step of determining as a value, In the third step, the total amount calculated in the fourth step
Compares the threshold value determined in the fifth step
A new call if the total volume exceeds the threshold.
2. The plural element according to claim 1, wherein is determined to be a call loss.
Traffic admission control method. 3. Interference wave currently used for communication
The sixth step of calculating the total amount of power value of, Maximum allowable interference power in shared frequency band
Interference wave power that increases when a new call is accepted from the value
The value obtained by subtracting the maximum value of
Has a seventh step and In the third step, the total sum calculated in the sixth step
And comparing the threshold value determined in the seventh step
If the sum exceeds the threshold, a new call
2. The plural element according to claim 1, wherein is determined to be a call loss.
Traffic admission control method.