JP3179021B2 - Mobile communication 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 code division multiple access (code division multiple access) between a plurality of radio base stations and these radio base stations.
The present invention relates to a call admission control method for mobile communication with a plurality of mobile stations communicating using an ision multiple access (CDMA) method, and more particularly to a call admission control method for mobile communication in which a plurality of types of services exist.

[0002]

2. Description of the Related Art In a currently widespread cellular phone or car phone system, the radius of a wireless zone served by one wireless base station is set to about several kilometers, and a large number of wireless base stations are arranged in a service area. Cellular systems that provide services are well known.

In general, in a mobile communication system using a limited radio frequency band, there is a trade-off relationship between system capacity (maximum applied traffic for satisfying a predetermined call loss rate) and communication quality. Exists. Conventional frequency division multiple access (Frequency Division Multiple Access:
FDMA) and Time Division Multiple Access (Time Division Multiple Access)
In the Access) system, in a system in which channels are fixedly arranged at each radio base station, a desired signal-to-interference wave power ratio (Carrier to Interference) determined from required communication quality is used.
A limit value of power ratio (CIR) is defined, and the repetition distance of the same channel or an adjacent channel is determined so that the locational degradation rate of the CIR becomes equal to or less than a predetermined value.

[0004] If the repetition distance is shortened, the number of channels allocated to each base station can be increased, and the system capacity can be increased, but the deterioration rate of the communication quality is increased. Although the communication quality degradation rate can be kept low, the number of channels that can be allocated to each wireless base station decreases, and the system capacity decreases.

[0005] This is so-called Dynamic Channel Assignment (Dynamic Channel Assignment) which dynamically assigns a channel for each call.
The same applies to Assignment (DCA). In DCA, it is determined whether a channel that is a base station is available.
Judgment is made based on the measurement of the repetition distance and the amount of interference. F
In DMA and TDMA, determining whether to use a wireless channel based on the amount of interference is conceptually equivalent to determination based on the repetition distance. If this judgment is relaxed (such as shortening the repetition distance or increasing the interference threshold), the system capacity increases, but the communication quality deterioration rate increases.

As described above, in the conventional FDMA and TDMA systems, the threshold of the repetition distance or the amount of interference for guaranteeing the communication quality is determined in advance, and then, according to the traffic situation of each radio base station. He was designing the layout of wireless channels.

On the other hand, the CDMA system is a system in which each user shares the same radio frequency band by using different spreading codes, and a channel is constituted by a spreading code. In a communication system using this CDMA system, when the same frequency band is used, a very large number of communications in all cells are sources of interference, and regardless of which spreading code each user uses for communication, The communication quality is determined by the total amount of interference.

Therefore, the same spreading code is used at a geographically distant place by using a method of guaranteeing communication quality by the repetition distance of a channel as in a conventional FDMA or TDMA system in a CDMA system. Even so, if the interference from the communication using another spreading code in the adjacent wireless base station is high, the CIR deteriorates, so that there is a problem that the communication quality cannot be guaranteed.

Therefore, in a CDMA system, in order to guarantee communication quality, it is necessary to suppress the number of interference sources. There are various techniques for suppressing the amount of interference, such as sectorization and voice activation. However, in order to reduce the amount of interference to a reference value or less when these conditions are given, it is necessary to simultaneously establish a connection with a certain user. Will be limited by the number. In Japanese Patent Application No. 7-326056, "Call admission control method for mobile communication", a method of call admission control in the case of one type of service is provided after guaranteeing a predetermined communication quality deterioration rate. A method of calculating the maximum number of simultaneously connected users that satisfies the call loss rate, and rejecting the reception when the number of connected users exceeds the maximum number of simultaneously connected users when a call occurs,
And the prescribed communication quality degradation rate, the threshold of the amount of interference that guarantees the call loss rate is calculated in advance, and if the amount of interference observed when a call occurs exceeds this threshold, This shows how to reject the reception.

[0010] On the other hand, in multimedia communication, it is desired to construct a flexible network capable of transmitting signals with high quality at a wide range of transmission rates from several kbps to several Mbps. In such a network, traffic design or control when a plurality of service types are mixed is very important.

[0011]

However, Japanese Patent Application No. Hei 7-3
No. 26056 “Call admission control method for mobile communication” does not consider the case where a plurality of service types coexist, and if call admission control is performed as it is, the call loss rate and the communication quality deterioration rate are significantly deteriorated, There is a serious problem that is unfavorable in practice, in which unfairness occurs depending on the service type.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has a plurality of radio base stations and a plurality of mobile stations which communicate with the radio base stations by using the CDMA system when there are mixed service types. In the mobile communication system consisting of, it is possible to flexibly cope with fluctuations in various conditions such as traffic and service types and changes in propagation conditions, and to satisfy a predetermined communication quality, and to set a predetermined connection quality (call loss rate). It is an object of the present invention to provide a mobile communication call admission control method that can be satisfied.

[0013]

In order to achieve the above object, according to the present invention, a call is accepted for a frequency band shared by a plurality of mobile stations communicating with a radio base station by code division multiple access. A mobile communication call admission control method for controlling, comprising means for storing a plurality of thresholds for a plurality of call reception corresponding to the type of service,
A means for measuring the current traffic or an amount corresponding thereto, and selecting one from the plurality of thresholds based on the service type of the mobile station at the time of call acceptance;
When the measured traffic is equal to or larger than the selected threshold value, a control to reject the call is performed.

[0014] The present invention described in claim 2 is the same as claim 1.
In the invention described in the above, the radio base station is provided with means for managing the number of users for each service type currently being communicated, the threshold for call reception is determined as the maximum number of simultaneously connected users for each service type, In this case, the gist is to reject the call when the current number of connected users belonging to the service type of the mobile station is equal to or larger than the selected threshold value.

Further, the present invention described in claim 3 provides the invention according to claim 1.
In the described invention, a means for measuring the amount of interference at the radio base station is provided, and a threshold value for call acceptance is determined as a maximum allowable amount of interference for each service type, and the measured amount of interference is selected. The gist of the present invention is to reject the call when it is equal to or more than the threshold.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the wireless base station includes means for managing the total number of currently connected wireless lines of all service types,
The threshold for call reception is defined as the maximum number of simultaneously connected lines for each service type, and when the total number of currently connected wireless lines of all service types is equal to or greater than the selected threshold at the time of call reception. The gist of the invention is to reject the call.

The present invention described in claim 5 is the same as claim 2.
In the invention described, the maximum number of concurrently connected users of the service type and the applied traffic volume of the service type for accepting a call when the call loss rate represented by the Erlang B formula for each service type becomes equal to the required value. The first relationship and the second relationship between the maximum number of simultaneously connected users of the service type for accepting calls when the communication quality deterioration rate of the service type is equal to the required value and the applied call volume of the service type From the above, the maximum applied call volume in the frequency band for which the call loss rate of the service type is equal to or less than the required value and the communication quality deterioration rate of the service type is equal to or less than the required value is determined. Within the range, the maximum of the service type for accepting calls in the frequency band in which the communication quality degradation rate of the service type is equal to or less than the required value with respect to the applied traffic volume By the time the number of connected users said second relationship, is predetermined for each service type, and the gist to carry out refuse controlling acceptance of new calls to be the maximum number of simultaneous users or more.

Further, the present invention according to claim 6 provides the present invention as claimed in claim 3.
In the described invention, when a communication quality deterioration rate for each service type becomes equal to a required value, a first threshold value of an interference amount of the service type for call reception and an applied call volume of the service type are set. From the relationship and the second relationship between the threshold value of the interference amount of the service type for accepting a call when the call loss rate of the service type is equal to the required value and the applied traffic volume of the service type, Determine the maximum applied traffic in the frequency band for which the communication quality degradation rate of the type is equal to or less than the required value, and the call blocking rate of the service type is equal to or less than the required value, and within the range of the maximum applied traffic, Based on the second relation, the interference threshold of the service type for accepting a call in the frequency band in which the call loss rate of the service type is equal to or less than the required value with respect to the applied call volume is determined based on the second relationship. Predetermining for each type, and the gist to carry out refuse controlling acceptance of new calls to be more relevant interference thresholds.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a mobile communication system to which a mobile communication call admission control method according to an embodiment of the present invention is applied. In the mobile communication system shown in FIG. 1, a plurality of radio base stations 11 and the radio base stations 11
Modulates with one or more spreading codes depending on the call type
A plurality of mobile stations 13 connected and communicating using the DMA system
It is composed of In the present embodiment, each base station has one uplink (transmission from the mobile station 13 to the radio base station 11) and one downlink (transmission from the radio base station 11 to the mobile station 13) shared by a plurality of users. It is assumed that a frequency band is used and that all base stations use the same frequency band.

FIG. 2 is a block diagram showing a configuration of the radio base station 11 used in the mobile communication system shown in FIG. 1, and particularly showing a functional configuration of a portion related to call admission control. In the wireless base station 11 shown in FIG. 2, the baseband processing device 1 and the RF processing device 2 are devices used for transmitting and receiving user information via radio. Baseband processor 1, K _i number of the baseband processing unit, that is, the first baseband processing unit 1a, the second
, The K- _th baseband processing section 1 _i (hereinafter simply referred to as baseband processing section). Further, the baseband processing device 1
It is connected to a multiplexing / demultiplexing device 3 for multiplexing / demultiplexing information of a plurality of users and interfacing with an exchange. On the other hand, a call processing control device 4, a call admission control device 5, a communication channel control device 6, and a memory 7 are interconnected via a bus 8 as devices for controlling the baseband processing sections 1a to 1i and for controlling the call. Have been. Further, the call processing control device 4 also has a role of an interface with a control station installed for controlling the radio base station.

The call admission control device 5 reads, updates, and writes data stored in the memory 7 in response to a request from the call processing control device 4, and performs current communication with the radio base station 11. The mobile station 13 manages a spreading code used by the mobile station 13. Communication channel control device 6
Manages the K _i pieces of the base band processing unit 1a~1i. Further, in the memory 7, the use status of the spreading code, the number of used spreading codes M _{i of} the service type i, the number of currently connected users C _i , the number of currently used lines D, and the maximum simultaneous connection for call admission control The number of users N _i , the interference threshold I _i , the maximum number of simultaneously connected lines E _{i, and the} like are stored. Here, each service type is described by an average transmission rate, a transmission rate, the number of simultaneously used spreading codes, and a combination thereof.

FIG. 3 is a flowchart showing a processing procedure of the call admission control method in the mobile communication system shown in FIGS.

The processing procedure of the call admission control method will be described with reference to the flowchart shown in FIG. The procedure for performing this processing is exactly the same regardless of the number of service types. Therefore, here, the case where there are two service types will be described as an example. In FIG. 3, when there is a new call connection request from the call processing control device 4 in step S13, the process proceeds to step S14, and the service type of the new call is notified to the base station. Thereafter, the process proceeds to the processing for each service type, and proceeds to step S15, where the call admission control device 5 checks whether there is a spreading code that is not currently in use for each call type. If all the spreading codes are in use, the process proceeds to step S17, and the fact is notified to the call processing control device 4, and the process ends.

If there is an available spreading code in step S15, the process proceeds to step S16, where the call admission control device 5 checks with the communication channel control device 6 whether there is a baseband processing unit that is not currently in use. Make an inquiry about whether If there is no usable baseband processing unit in step S16, the process proceeds to step S17, where the communication channel control device 6 notifies the call processing control device 4 of the fact through the call admission control device 5, and executes the process. finish.

If there is a usable baseband processing unit in step S16, the process proceeds to step S18, where the call admission control device 5 determines that the user of the service type i which is currently communicating within the own radio base station 11. read the number C _i from the memory is compared with the maximum number of simultaneous users N _i of service type i in also in the memory in step S19. If towards the maximum number of simultaneous users N _i from the number of users C _i of the service type i currently communicating is not large, that is, when they are equal, the process proceeds to step S17, the refusal of the connection of the new call It notifies the call processing control device 4 and terminates the processing.

[0027] When the larger number of connected users C _i than the maximum number of simultaneous users N _i of call type i currently communicating, the process proceeds to step S20, allocates a baseband processing unit and the diffusion code, that The contents are registered in the memory (step S21). Furthermore, the number of connected users C _i of the service type i in the step S22 currently in communication is increased by one.

Further, the call admission control device 5 executes step S1.
If there is a disconnection request from the call processing control device 4 in step 1, the process proceeds to step S23, where the service type is confirmed, and the process proceeds to each service type.

When the service type is confirmed, the process proceeds to step S24, where the baseband processing unit is released through the communication channel control device, and the data of the corresponding mobile station 13 in the memory 7 is deleted (step S25). Further, in step S26, the number of connected users currently communicating is reduced by one.

Next, described below how to set up the number of simultaneous users N _i is a call acceptance threshold service type i. Here, transmission power control based on the reception level is assumed. Also, the maximum value of the service type is i
Considering _max and the transmission rate, each user of the service type i is assumed to transmit independently at a probability (time rate) ρ _i and to take a transmission stop state at a probability (1−ρ _i ) independently.

Assuming that a call of the service type i is a random call having an occurrence rate λ _i and a termination rate μ _i, a call loss rate P _{block, i} when the number of simultaneously connected users n _i and the applied traffic volume a _i [Erlangs] is satisfied. Is Erlang B formula

(Equation 1) More required. Therefore, loss probability calculated when substituting service application traffic intensity a _i [Erlangs] of type i in the current time, the minimum number of simultaneous users n among the concurrent number of users n _i to be less required call loss rate _{Find min, i} (≦ n _i ).

Calculated by substituting the number n _i of concurrently connected users within the range where the call loss rate of service type i is equal to or less than the required call loss rate (n _{min, 1} ≦ n _i ) and the applied traffic volume a _i [Erlangs]. is the communication quality deterioration ratio P _loss, the maximum value n _max of the number of simultaneous users n _i as _i becomes less communication quality deterioration rates is required _to determine the _i. Since the calculation procedure is the same regardless of the number of service types, the communication quality deterioration rate P _{loss, 0} of service type 0 is shown below, taking as an example the case where two service types 0 and 1 are mixed.

[0033]

(Equation 2) Here, P _k (k ₀ , k ₁ ) is the probability that the number of transmitting users for each service type is (k ₀ , k ₁ ).

(Equation 3) And C _{max, 0} shown below is a limit value of the number of transmitting users determined from transmission characteristics,

(Equation 4) I _{0, reqo} is the limit value of the allowable interference amount, and R ₀ is the reception power at the base station of the user whose service type is 0. Also, the integral term of the numerator

(Equation 5) Represents an out-of-cell interference amount, and Erfc (x) represents an error complement function.

[0034]

(Equation 6) FIG. 4 is a flowchart showing a processing procedure of a call admission control method according to another embodiment in the mobile communication system shown in FIGS.

The processing procedure of the call admission control method will be described with reference to the flowchart shown in FIG. The procedure for performing this processing is exactly the same regardless of the number of service types. Therefore, here, the case where there are two service types will be described as an example. In FIG. 4, when there is a connection request for a new call from the call processing control device 4 in step S13, the process proceeds to step S14, and the service type of the new call is notified to the base station. Thereafter, the process proceeds to the processing for each service type, and proceeds to step S15, where the call admission control device 5 checks whether there is a spreading code that is not currently in use for each call type. If all spreading codes are in use, the process proceeds to step S17, and the call processing control device 4
And terminates the process.

If there is a spreading code that can be used in step S15, the process proceeds to step S16, where the call admission control device 5 checks with the communication channel control device whether there is a baseband processing unit that is not currently in use. Make an inquiry. If there is no usable baseband processing unit in step S16, the process proceeds to step S17, where the communication channel control device 6 notifies the call processing control device 4 of the fact through the call admission control device 5, and executes the process. finish.

If there is a usable baseband processing unit in step S16, the process proceeds to step S30, in which the call admission control device 5 receives signals from all the mobile stations which are currently communicating within the own radio base station 11. The measured interference power I _all is measured and compared with the interference threshold I _i of the service type i in the memory in step S31. If towards the interference power I _all than the interference threshold I _i received from all mobile stations currently in communication is not large, that is, when they are equal, the process proceeds to step S17, the refusal of the connection of the new call It notifies the call processing control device 4 and terminates the processing.

[0038] When towards the interference threshold I _i of the interference power I _all from call type i received from all mobile stations currently in communication is large, the process proceeds to step S20, the allocation of the baseband processing unit and the diffusion code Then, the contents are registered in the memory (step S21). Furthermore, the number of connected users C _i of the service type i in the step S22 currently communicating 1
Just increase.

The call admission control device 5 determines in step S1
If there is a disconnection request from the call processing control device 4 in step 1, the process proceeds to step S23, where the service type is confirmed, and the process proceeds to each service type.

When the service type has been confirmed, the process proceeds to step S24, where the baseband processing unit is released through the communication channel control device 6, and the data of the corresponding mobile station 13 in the memory 7 is deleted (step S25).
Further, in step S26, the number of connected users currently communicating is reduced by one.

The method of setting the interference threshold value I _{i for} the service type i is as follows. The limit value C _{max, i} of the number of transmitting users is calculated according to the equation (4) determined from the transmission characteristics for each service type. Can be obtained in exactly the same way by substituting into the calculation formula of the interference threshold value in Japanese Patent Application No. 7-326056 “Call admission control method for mobile communication”. This method is described in detail in Japanese Patent Application No. 7-326056, and will not be described here.

FIG. 5 is a flowchart showing a processing procedure of a call admission control method according to another embodiment in the mobile communication system shown in FIGS. 1 and 2.

The processing procedure of the call admission control method will be described with reference to the flowchart shown in FIG. The procedure for performing this process is exactly the same regardless of the number of service types. Therefore, here, the case where there are two service types will be described as an example. In FIG. 5, when there is a connection request for a new call from the call processing control device 4 in step S13, the process proceeds to step S14 to notify the base station of the service type of the new call. Thereafter, the process proceeds to the processing for each service type, and proceeds to step S15, where the call admission control device 5 checks whether there is a spreading code that is not currently in use for each call type. If all the spreading codes are in use, the process proceeds to step S17, and the fact is notified to the call processing control device 4, and the process ends.

If there is a usable spreading code in step S15, the process proceeds to step S16, where the call admission control device 5 determines whether the communication channel control device 6 has a baseband processing unit that is not currently in use. Make an inquiry about whether If there is no usable baseband processing unit in step S16, the process proceeds to step S17, where the communication channel control device 6 notifies the call processing control device 4 of the fact through the call admission control device 5, and executes the process. finish.

If there is a usable baseband processing unit in step S16, the process proceeds to step S40, where the call admission control device 5 stores the number D of lines currently connected in the radio base station 11 from the memory 7. reading, similarly compared with the maximum number of simultaneous connections lines E _i of service type i in the memory in step S41. If the current is not greater in the maximum number of concurrent connections lines E _i from the line number D in the connection, i.e. if they are equal, the process proceeds to step S17, the call processing control device refusal of connection of a new call 4 And terminates the process.

[0046] When towards the maximum number of concurrent connections lines E _i from the line number D currently connected is large, the process proceeds to step S20, allocates a baseband processing unit and the diffusion code, the content of the memory 7 Register (Step S2
1). Further, in step S42, the number of currently connected lines D
Is increased by the number of used spreading codes M _i of the service type i.

Also, the call admission control device 5 determines in step S1
If there is a disconnection request from the call processing control device 4 in step 1, the process proceeds to step S23, where the service type is confirmed, and the process proceeds to each service type.

When the service type is confirmed, the process proceeds to step S24, where the baseband processing unit is released through the communication channel control device 6, and the data of the corresponding mobile station 13 in the memory 7 is deleted (step S25).
Reducing the number of lines currently connected only using spreading codes number M _i of the service type i in addition the corresponding service type at step S43.

Next, an example of how to set up simultaneous connections lines E _i is a call admission decision threshold of the service type i below.

The maximum number of simultaneously connected lines E _i

[Equation 7] [Maximum number of simultaneously connected lines: E _i ] = [Total number of lines] (1− [Ratio of service type i]) (7) However, the applied traffic of service types 0 and 1
Each use spread the applied traffic intensity as the total applied traffic intensity A when using the number of spreading codes respectively set to _{a 0, a 1, M 0} , M 1 A = a 0 M 0 + M 1 a 1 (8) The traffic volume is weighted by the code numbers M ₀ and M ₁ , and the ratio r ₁ of the service type 1 is defined as follows.

[0051]

(Equation 8)

[0052]

As described above, according to the present invention,
A plurality of thresholds for a plurality of call receptions corresponding to service types are provided as a maximum number of simultaneously connected users, an amount of interference, and a maximum number of simultaneously connected lines. One of the thresholds is selected, and call reception is controlled based on the selected threshold, so that even when a plurality of service types are mixed, call reception control can be performed accurately. it can.

Further, according to the present invention, since the call acceptability judgment is made based on the maximum number of simultaneously connected users, it can be realized by extremely simple control, and the predetermined call loss rate and the communication quality deterioration rate are satisfied. Since the maximum number of simultaneously connected users is determined, the system can be operated so as to guarantee a predetermined call loss rate and communication quality deterioration rate.

Further, according to the present invention, the call admissibility determination is performed based on the interference threshold value obtained separately for each service type. Therefore, the adaptability to the variation of the applied call volume is extremely high, and the system design is flexible. / Operation can be realized.

Further, according to the present invention, it is possible to operate the system so as to guarantee a predetermined call loss rate and a communication quality deterioration rate as in the case of the call reception method based on the maximum number of simultaneously connected users.

Further, according to the present invention, the call acceptance decision is made by changing the maximum number of simultaneously connected lines according to the service type, thereby eliminating unfairness between service types which may be caused by a difference in the number of spread codes used. Can be. In other words, by securing a larger number of lines for a call that uses a larger number of spreading codes at a time, priority can be given to a service type that may deteriorate in quality. In addition, since the maximum number of simultaneously connected lines is determined based on the ratio of service types, it is possible to set a threshold for judging call acceptance by service type extremely easily.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a mobile communication system to which a mobile communication call admission control method according to an embodiment of the present invention is applied.

FIG. 2 is a block diagram showing a functional configuration of a part related to a call admission control of a radio base station used in the mobile communication system shown in FIG. 1;

FIG. 3 is a flowchart showing a control process of a call admission control method in the mobile communication system shown in FIGS. 1 and 2;

FIG. 4 is a flowchart showing a control process of a call admission control method of another embodiment in the mobile communication system shown in FIGS. 1 and 2;

FIG. 5 is a flowchart showing a control process of a call admission control method in another embodiment in the mobile communication system shown in FIGS. 1 and 2;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 baseband processor 1a-1n baseband processor 2 RF processor 3 multiplexer / demultiplexer 4 call processing controller 5 call admission controller 6 communication channel controller 7 memory

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04B ⁷ /24-7/26 H04J 13/00-13/06 H04Q 7/00-7/38

Claims (6)

(57) [Claims] A mobile communication call admission control method for controlling call admission for a frequency band shared by a plurality of mobile stations communicating with a radio base station by code division multiple access, the method corresponding to a service type. Providing means for storing a plurality of thresholds for a plurality of call admissions, wherein
Or means for measuring an amount corresponding thereto, and selecting one of the plurality of thresholds based on the service type of the mobile station at the time of accepting the call, and selecting the measured traffic.
When the lock is above this selected threshold ,
A call admission control method for mobile communication, characterized by performing a control for rejecting the admission of a call . 2. A radio base station comprising means for managing the number of users for each service type currently in communication, a threshold for call reception being determined as the maximum number of simultaneously connected users for each service type, 2. The call reception of mobile communication according to claim 1, wherein the reception of the call is rejected when the current number of connected users belonging to the service type of the mobile station is equal to or larger than the selected threshold value. Control method. 3. A radio base station comprising means for measuring an interference amount, a threshold value for call acceptance is determined as a maximum allowable interference amount for each service type, and the measured interference amount is selected. 2. The call admission control method for mobile communication according to claim 1, wherein the call admission is rejected when the call is equal to or larger than the threshold value. 4. A radio base station comprising means for managing the total number of currently connected radio channels of all service types,
The threshold for call reception is defined as the maximum number of simultaneously connected lines for each service type, and when the total number of currently connected wireless lines of all service types is equal to or greater than the selected threshold at the time of call reception. 2. The call admission control method for mobile communication according to claim 1, wherein the call reception is rejected. 5. An Erlang B formula for each service type
The first relationship between the maximum number of concurrently connected users of the service type for accepting calls when the call loss rate equals the required value and the applied call volume of the service type, and the communication quality deterioration rate of the service type are From the second relationship between the maximum number of concurrently connected users of the service type and the applied traffic volume of the service type for accepting calls when equal to the required value, the call loss rate of the service type is equal to or less than the required value. And the communication quality deterioration rate of the service type is less than the required value.
Find the maximum applied traffic in the frequency band for the certain, within the range of the maximum applied traffic, for the applied traffic,
If the communication quality deterioration rate of the service type is less than the required value
Made by the second relationship the maximum number of simultaneous connections the user of the service type for the call admission in that frequency band, is predetermined for each service type, the maximum concurrent connections Yoo
The call admission control method for mobile communication according to claim 2, wherein control is performed to reject the reception of a new call having the number of users or more . 6. applied traffic intensity thresholds and the service type of the interference amount of the service type for the call reception when the communication quality deterioration rate of each service type is equal to its <br/> required value and as required first relationship and loss probability of the service type of
From the second relationship between the threshold value of the interference amount of the service type for accepting the call when the value becomes equal to the value and the applied traffic volume of the service type, the communication quality deterioration rate of the service type is determined.
Is less than or equal to the required value , and finds the maximum applied traffic in the frequency band for which the call loss rate of the service type is equal to or less than the required value , and within the range of the maximum applied traffic,
The applied traffic intensity, blocking probability of the service type is the place
By the second relationship interference threshold of the service type for the call admission in that frequency band of less principal value, it is predetermined for each service type, the interference thresholds than
3. call admission control method for mobile communications, wherein the performing refuse controlling acceptance of new calls to be on.