JP2909009B2 - Mobile communication call admission control method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plurality of radio base stations and code division multiple access (CDMA;
The present invention relates to a method and an apparatus for controlling call admission of mobile communication with a plurality of mobile stations communicating using a Code Division Multiple Access (Code Division Multiple Access) method.

[0002]

2. Description of the Related Art At present, in a mobile telephone system or a mobile telephone system, a radius of a wireless zone served by one wireless base station is set to several kilometers, and a large number of wireless base stations are arranged in a service area. Cellular systems that provide services by doing so 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, which is the maximum applied call volume for satisfying a preset call blocking rate, and communication quality. Exists.

[0004] Conventional frequency division multiple access (Frequency Diplexing)
In a system of vision multiple access (FDMA) or time division multiple access (TDMA), in a system in which channels are fixedly arranged at each radio base station, a desired wave to an interference wave determined by required communication quality. Carrier to Interference power Ratio; CI
The limit value of R) is defined, and the repetition distance of the same channel or adjacent channel is determined so that the locational deterioration rate of the CIR becomes equal to or less than a predetermined value.

If the repetition distance is shortened, the number of channels arranged in each base station can be increased, and the system capacity increases, but the communication quality degradation rate increases. Conversely, if the repetition distance is increased, the communication quality degradation rate can be suppressed low, but the number of channels that can be allocated to each wireless base station decreases, and the system capacity decreases.

[0006] This is so-called Dynamic Channel Assignment (Dynamic Channel Assignment).
The same applies to nel assignment (DCA). In this DCA, whether or not a channel as a certain base station can be used is determined based on the measurement of the repetition distance, the amount of interference, and the like.

In FDMA and TDMA, determining whether to use a radio 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 threshold value of the amount of interference), the system capacity increases, but the deterioration rate of communication quality increases.

As described above, in the conventional FDMA or TDMA system, the repetition distance or the threshold value of the amount of interference for guaranteeing the communication quality is determined in advance, and
The layout design of the wireless channel has been performed according to the traffic situation of each wireless base station.

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 this CDMA system, all other communications using the same frequency band cause interference. Therefore, when the same frequency band is used in all cells, a very large number of communication waves in all cells become interference sources, and the total amount of interference is independent of which spreading code each user uses for communication. Determines the communication quality.

For this reason, the same spreading code is used in geographically distant places 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 in this case, if interference from communication using another spreading code in a nearby wireless base station is high, CIR deteriorates, so that there is a problem that communication quality cannot be guaranteed.

In such a CDMA system, it is necessary to suppress the number of interference sources in order to guarantee communication quality. Sectorization, a technology to reduce the amount of interference,
There are various techniques such as voice activation, but when those conditions are given, in order to suppress the amount of interference to a reference value or less, the number of users simultaneously establishing a connection is limited. For example, AMViterbi and AJVite
rbi, “Erlang Capacity of a Power Controlled CDMA S
ystem, ”IEEE Journal on Selected Areas inCommunica
tions, Vol.11, No.6, pp.892-900, Aug.1993.
As a method of call admission control, a threshold of the amount of interference is determined in advance, and a method of rejecting reception when the amount of interference observed when a call has occurred exceeds this threshold is shown.
By approximating the time congestion rate, the relationship between the applied traffic and the blocking rate is obtained. However, this method has a drawback that the communication quality cannot be guaranteed because only the relationship between the call loss rate and the applied call volume is obtained.

Further, a call admission control method that satisfies a given call loss rate while guaranteeing a predetermined communication quality deterioration rate is disclosed in Japanese Patent Application No. 7-158036. In this method, a first relationship between the maximum number of simultaneously connected users and an applied call volume in the frequency band for guaranteeing a required communication quality obtained based on the communication quality deterioration rate, and a required relationship obtained based on the call loss rate From the second relationship between the maximum number of simultaneously connected users and the applied traffic in the frequency band to satisfy the call loss rate, the communication quality of use is guaranteed, and in the frequency band to satisfy the predetermined call loss rate. The maximum applied traffic is determined, and within the range of the maximum applied traffic, the maximum number of simultaneously connected users in the frequency band for satisfying the required call loss rate with respect to the applied traffic is predetermined by the second relationship. This is a method for controlling the acceptance of a new call.

[0013]

However, when this method is used for designing an actual mobile communication system,
There is a problem that the radio wave propagation situation and the traffic distribution need to be obtained in detail by actual measurement or theoretical calculation, and a great deal of labor is required for designing. In addition, in actual mobile communication systems, radio wave propagation conditions and traffic distributions change significantly due to the construction / demolition of surrounding buildings or the construction of new roads. Although the method is adopted, in such a case, redesign is required, and there is a problem that adaptability to system expansion is low.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has a plurality of radio base stations, and a radio base station and a CDMA system.
In a mobile communication system composed of a plurality of mobile stations connected and communicating using a method, a call admission control which can guarantee a predetermined communication quality and satisfy a predetermined call loss rate is performed by autonomous distribution for each radio base station. It is intended to be realized by control.

[0015]

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 call admission control method for controlling mobile communication, comprising: calculating a call loss rate in the own radio zone and a communication quality deterioration rate, and calculating the maximum call loss rate in the own radio zone based on the calculated call loss rate and the communication quality deterioration rate. The gist is to calculate the number of simultaneously connected users.

A ninth aspect of the present invention is a mobile communication call admission control apparatus 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. A first calculating means for calculating a call loss rate in the own wireless zone, a second calculating means for calculating a communication quality deterioration rate in the own wireless zone, and a call loss rate calculated by the first calculating means. A third calculating means for calculating the maximum number of simultaneously connected users in the own wireless zone based on the communication quality deterioration rate calculated by the second calculating means.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing a configuration of a mobile communication system to which the call admission control method of the present invention is applied. The mobile communication system shown in FIG. 1 includes a plurality of radio base stations 11 and a plurality of mobile stations 12 which communicate with these radio base stations 11 by using one or a plurality of spreading codes. In the present embodiment, each base station is shared by a plurality of users for an uplink (that is, transmission from a mobile station to a radio base station) and a downlink (that is, transmission from a radio base station to a mobile station).
One frequency band, and all radio base stations 1
1 will be described assuming that the same frequency band is used.

FIG. 2 is a block diagram functionally showing, in particular, the configuration of a portion related to call admission control in the configuration of the radio base station 11 used in the mobile communication system shown in FIG. Hereinafter, the configuration of the wireless base station 11 will be described in detail with reference to FIG.

First, K _i corresponding to K _i spreading codes
The baseband processing units 111 are connected between the RF processing unit and the communication channel control device 112. Each baseband processing unit 111 corresponds to a transceiver in an FDMA or TDMA system, and includes an encoder for spreading an input signal by a spreading code, and a correlation for extracting a signal corresponding to the self spreading code from a demodulated signal. It is composed of vessels and the like.

The communication channel control device 112 includes a call admission control device 113 and a maximum simultaneous connection user number control device 1.
16 are connected. This communication channel control device 11
2 manages K _i baseband processing units 111.

Further, the call admission control device 113 is connected to a memory 114, a call processing control device 115, and a maximum simultaneous connection user number control device 116. Also, the memory 11
4 is also connected to the maximum number of concurrently connected users control device 116,
Are the communication channel control device 112 and the call processing control device 11
3 and the memory 114.

The call admission control unit 113 reads, updates, and writes data stored in the memory 114 in response to a request from the call processing control unit 115, and communicates with the radio base station 11 And the spreading code used by the mobile station that performs the communication.

The maximum number of concurrently connected users control device 116
Collects information related to the call loss rate based on the notification of the success / failure of the incoming / outgoing call from the call admission control device 113 and the communication quality deterioration rate based on the communication quality measurement result report from the communication channel control device 112. Collect information related to
The maximum number of simultaneously connected users is determined and registered in the memory 114. That is, the maximum number of concurrently connected users control device 116
Constitutes first, second and third calculation means.

The memory 114 stores the use status of the spreading code, the current number of connected users C, the maximum number of simultaneously connected users N for call admission control, call loss rate information, communication quality deterioration rate information, and the like. .

Next, the processing procedure of the call admission control method will be described with reference to the flowchart shown in FIG. FIG. 3 is FIG.
3 is a flowchart showing a processing procedure of a call admission control method in the mobile communication system shown in FIG. 2. In the formulas in the figure, “=” means substitution, and C = C−1, C = C
+1 means that C is decreased by 1 and C is increased by 1, respectively.

Referring to FIG. 3, first, in step S13, when there is a request for connection of a new call from the call processing control device 115, the call admission control device 113 proceeds to step S15, and there is an available spreading code. Check if you want to. If all the spreading codes are unusable, the process proceeds to step S17, and the fact is notified to the call processing control device 115, and the process ends.

If there is a spreading code that can be used in step S15, the process proceeds to step S19, where the call admission control device 113 determines whether there is a usable baseband processing unit 111 for the communication channel control device 112. Make an inquiry about whether Usable baseband processor 1
If 11 does not exist, the process proceeds to step S17, where the communication channel control device 112 notifies the call processing control device 115 of the fact through the call admission control device 113, and ends the processing.

If there is a usable baseband processing unit 111 in step S19, the call admission control unit 11
In step S21, the number of users C currently performing communication in the own radio base station is read from the memory 114 in step S21, and is compared with the maximum number of simultaneously connected users N in the memory 114 in step S23. Whether both are equal (N =
C) or the number of currently communicating users C is larger (N
In the case of <C), the process proceeds to step S17, in which the call processing control device 115 and the maximum number of concurrently connected users control device 116 are notified that connection of a new call is to be rejected, and the process ends.

If not (C <N), step S2
Proceeding to 5, the baseband processing unit 111 and the spreading code are allocated, and the contents are registered in the memory 114 (step S27). Further, in step S29, the number C of users currently communicating is increased by one. In addition, the maximum number of concurrently connected users control device 116 indicates that a new call has been accepted.
Notify.

When the call admission control device 113 receives a disconnection request from the call processing control device 115 at step S11, the call admission control device 113 proceeds to step S31.
2, the baseband processing 111 is released, and the data of the corresponding mobile station 12 in the memory 114 is deleted in step S33. Further, in step S35, the number of currently used users C is decreased by one.

Next, the operation of the maximum number of concurrently connected users control device 116 will be described in detail with reference to FIG. FIG.
FIG. 7 is a diagram for explaining a state transition of the maximum number of concurrently connected users control device 116.

In the own radio zone, the number of outgoing calls, the number of incoming calls,
In the case of calculating the call loss rate by measuring the number of incomplete calls and the number of incoming and outgoing calls, when the maximum number of concurrently connected users control device 116 receives the call reception result notification from the call reception control device 113 in the standby state T1, Transition to the loss probability information collection state T3,
The call loss rate information collection process is executed, and upon completion, returns to the standby state T1.

When calculating the call loss rate by measuring the amount of traffic carried in the own radio zone, the maximum number of concurrently connected users control device, when in the standby state T1, collects the call loss rate information at every call loss rate information collection cycle. The state transits to the state T3, executes the call loss rate information collection process, and when completed, returns to the standby state T1.

FIG. 4 shows only the state transition when the number of outgoing calls, the number of incoming calls, and the number of outgoing / incoming calls in the own radio zone are measured to calculate the call loss rate.

The maximum concurrently connected user number control device 11
6 transitions to the communication quality information collection state T5 for each communication quality information collection cycle in the standby state T1, executes the communication quality information collection process, and returns to the standby state T1 when the processing ends.

In the standby state T1, the maximum concurrently connected user number control device 116 transits to the maximum concurrently connected user number update state T7 at every maximum concurrently connected user number update period, and executes the maximum concurrently connected user number update process. And when finished,
The state transits to the communication quality information loss probability information update state T9. After executing the communication quality information loss probability information update process, the process returns to the standby state T1 when the process is completed.

FIG. 5 shows the maximum number of concurrently connected users control device 1 among the variables and constants stored in the memory 114.
16 conceptually shows what is used. For example, "a
ttempt "," block "and" block r
"ate" is a variable that is updated based on the call reception result notification from the call reception control device 113, and represents the number of incoming and outgoing calls, the number of call losses, and the call loss rate, respectively. Also, "goo
“d”, “bad”, and “outage” are variables that are updated based on the measurement result of the communication quality, and are the number of times that the communication quality is determined to be not deteriorated, and that the communication quality is determined to be deteriorated, respectively. And the communication quality degradation rate. “THRQ” is a constant used to obtain a communication quality deterioration rate and represents a threshold. When the measurement result of the communication quality is less than “THRQ”, it is determined that the communication quality has deteriorated. . "THRQ1", "THR
“Q2” and “THRB” are constants representing thresholds used for updating the maximum number of simultaneous connections in the maximum number of concurrently connected users update process, and are respectively a first threshold of the communication quality deterioration rate and a communication quality. 5 illustrates a second threshold value of the deterioration rate and a threshold value of the call blocking rate. Further, “N” is a variable used for call admission control, and is the maximum number of simultaneously connected users.

FIG. 6 is a flowchart showing a control procedure of a call loss rate information collection process in the case where the number of outgoing calls, the number of incoming calls, and the number of incomplete calls are measured and the call loss rate is calculated in the own radio zone. . In the formulas in the figure, “=” means substitution. The operator "++" indicates that the variable is increased by one.

First, based on the notification of the call reception result from the call reception control device 113, if the result is successful (step S41), the variable attempt is increased by 1 (step S47). Variable attemp
t (step S43) and variable block (step S43)
45) is increased by one. Further, the process proceeds to step S49, where the variable block rate to block
Substitute the result divided by mpt. The updated variables are stored in the memory 114, and the process ends.

FIG. 7 is a flowchart showing a control procedure of a call loss rate information collection process in a case where a call loss rate is calculated by measuring a traffic volume carried in the own radio zone. In the formulas in the figure, “=” means substitution. Also, the operator "+
"+" Indicates that the variable is increased by one.

First, the maximum concurrently connected user number control device 11
6 reads the current number of concurrently connected users C from the memory in step S51. Subsequently, in step S53, the number of simultaneously connected users C is compared with the maximum number of simultaneously connected users N. If C ≧ N, the variable attempt is used.
(Step S55) and variable block (Step S5)
7) is incremented by one, and if C <N, the variable atte
mpt is increased by 1 (step S59). Further, the process proceeds to step S61, where the variable block rate to bl
The result obtained by dividing ock by attempt is substituted. The updated variables are stored in the memory 114, and the process ends.

FIGS. 8 and 9 are flowcharts showing the control procedure of the communication quality information collection process. 8 and 9
Are a control procedure for measuring the signal-to-interference power ratio as the communication quality, and a control procedure for measuring the interference wave power as the communication quality, respectively. 8 and 9 are different from each other in comparison between the measurement result and the threshold. In the formulas in the figure, “=” means substitution. Also, the operator "+
"+" Indicates that the variable is increased by one.

First, the maximum concurrently connected user number control device 11
6 sends a communication quality measurement command to the communication channel control device 112 in step S71 (step S81 in FIG. 9, the same applies hereinafter). Based on the response from the communication channel control device 112, the measurement result is compared with THRQ in step S73. If the measurement result is less than THRQ, it is determined that the quality is degraded, and the variable bad is increased by 1 (step S75 (S85)). . If the measurement result is equal to or higher than THRQ, it is determined that the communication quality is satisfied, and the variable good is set to 1
It is increased (step S77 (S87)). Further, the result obtained by dividing bad by (bad + good) is substituted for the variable outage (step S79 (S89)). The updated variables are stored in the memory 114, and the process ends. When collecting the communication quality information, the maximum number of concurrently connected users control device 116
It is also possible to collect the downlink communication quality information by instructing the mobile station 12 to perform the communication quality measurement and execute the measurement.

FIG. 10 is a flowchart showing a control procedure of a process for updating the maximum number of simultaneously connected users. In the formulas in the figure, “=” means substitution. Also, the operator "+
The "+" indicates that the variable is increased by one, and the operator "-"
Indicates that the variable is decreased by one.

First, the maximum number of concurrently connected users control device 116
Are the variables outage and b stored on the memory
lock rate, and further constants THRQ1, THR
Read Q2 and THRB. The variable outage is equal to or greater than the constant THRQ1 (step S91), and the variable N is 0
If it is larger (step S99), the variable N is decremented by one and the process is terminated (step S101). Variable outag
If e is less than the constant THRQ1, further, in step S93, the variable block rate is compared with a constant THRB. Variable block If the rate is less than the constant THRB, the process ends.
Variable block If the rate is equal to or greater than the constant THRB, in step S95, the variable outag
Compare e with the constant THRQ2. If the variable outage is smaller than the constant THRQ2, the process proceeds to step S97, the variable N is increased by 1, and the process ends. Variable outage
Is equal to or greater than the constant THRQ2, the process ends.

FIG. 10 shows a processing procedure for confirming when decreasing N so that the variable N always becomes a non-negative integer. However, the variable N is set so that the variable N does not become too large. It is also conceivable to configure so as to check the value when increasing. In this case, the variable N
Is determined in advance, and when the variable N is to be increased, after confirming that the variable N is less than the maximum value,
The configuration may be such that the variable N is increased by one.

When the maximum concurrently connected users number updating process is completed in this way, the maximum concurrently connected users number control device 116 transits to the communication quality information call loss rate information update state T9. In this state, the variables attempt, block, block on the memory updated in the communication quality information collection state T5 and the call loss rate information collection state T3. rat
Initialize or update e, good, bad, and outage. The processing in this state includes, for example, 1) variables attempt, block, block r
a) a method of assigning all 0s to ate, good, bad, and outage; 2) The number of transitions to the maximum concurrently connected users update process is recorded, and a variable attempt every M times (M is an integer of 2 or more), block, block rate,
3) Assuming λ is a real number greater than 0 and less than 1, block = block × λ, block = block × λ, good = good × λ, bad = bad × λ Various methods such as a processing method of updating each variable can be considered, but the same effect can be obtained by using any method.

In the call admission control method and apparatus of the present invention, call loss rate information and communication quality information are collected for each radio base station, and the maximum number of simultaneously connected users is determined based on the results. Since the call acceptance determination is performed based on the maximum number of simultaneously connected users, it can be realized by extremely easy control,
In addition, since the maximum number of simultaneously connected users is determined so as to satisfy the predetermined call loss rate and the communication quality deterioration rate, the system can be operated so as to guarantee the predetermined call loss rate and the communication quality deterioration rate. Furthermore, since the call admission control method in the above-described embodiment is realized by autonomous distributed control for each radio base station, adaptability to system expansion is extremely high, and flexible system design / operation can be realized. It is possible.

In the above-described embodiment, each base station uses one frequency band shared by a plurality of users for uplink and downlink, and all base stations use the same frequency band. The description has been made on the assumption that the present invention is performed, but this does not limit the mobile communication system to which the present invention is applied. When a plurality of frequency bands are used in each base station, similar effects can be obtained by repeatedly applying the call admission control according to the present invention to each frequency band. Further, even when the frequency bands used in the respective base stations are not necessarily the same, the present invention can be applied and the same effects can be obtained.

[0050]

As described above in detail, the call admission control method according to the first aspect and the call admission control apparatus according to the ninth aspect collect call loss rate information and communication quality information for each base station, and obtain the results. The maximum number of concurrently connected users is determined based on this. Since the call acceptance determination is performed based on the maximum number of simultaneously connected users, it can be realized by extremely simple control, and the maximum number of simultaneously connected users is determined so as to satisfy a predetermined call loss rate and communication quality deterioration rate. Therefore, it is possible to operate the system so as to guarantee a predetermined call loss rate and a predetermined communication quality deterioration rate. Further, since the call admission control method according to the first aspect is realized by autonomous distributed control for each radio base station, adaptability to system expansion is extremely high, and flexible system design / operation can be realized. is there.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration example of a mobile communication system to which the present invention is applied.

FIG. 2 is a block diagram functionally showing the configuration of the wireless base station shown in FIG.

FIG. 3 is a flowchart showing a processing procedure of a call admission control method in the radio base station shown in FIG.

FIG. 4 is a diagram illustrating a state transition of the maximum number of simultaneously connected users control apparatus according to the present invention.

FIG. 5 is a diagram conceptually illustrating a state of variables and constants on a memory used by the maximum number of simultaneously connected users control device according to the present invention.

FIG. 6 is a flowchart showing a control procedure of a call loss rate information collection process according to the present invention.

FIG. 7 is a flowchart showing a control procedure of a call loss rate information collection process according to the present invention.

FIG. 8 is a flowchart showing a control procedure of a communication quality information collecting process according to the present invention.

FIG. 9 is a flowchart showing a control procedure of a communication quality information collection process according to the present invention.

FIG. 10 is a flowchart showing a control procedure of a process for updating the maximum number of concurrently connected users according to the present invention.

[Explanation of symbols]

 Reference Signs List 11 radio base station 12 mobile station 111 baseband processing unit 112 communication channel control device 113 call admission control device 114 memory 115 call processing control device 116 maximum simultaneous connection user number control device 117 RF processing unit

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-334597 (JP, A) JP-A-5-244071 (JP, A) JP-A-5-191856 (JP, A) 175767 (JP, A) JP-A-9-69824 (JP, A) JP-A-6-268576 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H04B 7 / 24-7 / 26 102 H04Q 7/00-7/38 H04M 3/00

Claims (16)

(57) [Claims] 1. A call admission control method for mobile communication for controlling call admission in a frequency band shared by a plurality of mobile stations communicating with a radio base station by code division multiple access, comprising: And a communication quality deterioration rate, and calculating the maximum number of simultaneously connected users in the own radio zone based on the calculated call loss rate and communication quality deterioration rate. . 2. The call admission control according to claim 1, wherein the call loss rate is calculated based on the number of outgoing calls, the number of incoming calls, and the number of incomplete calls in the own radio zone. Method. 3. The call admission control method according to claim 1, wherein the call loss rate is calculated based on the measured number of simultaneously connected users in the own radio zone. 4. The call admission control method according to claim 1, wherein the communication quality deterioration rate is calculated based on a signal-to-interference power ratio of a user communicating in the own radio zone to be measured. . 5. The call admission control method according to claim 1, wherein the communication quality deterioration rate is calculated based on the measured interference power in the own radio zone. 6. When the calculated communication quality deterioration rate exceeds a predetermined threshold value of the communication quality deterioration rate, the maximum number of simultaneously connected users in the own wireless zone is reduced. The call admission control method according to claim 1. 7. When the calculated call loss rate exceeds a preset threshold value of the call loss rate and the calculated communication quality deterioration rate does not exceed the threshold value of the preset communication quality deterioration rate. 2. The call admission control method according to claim 1, further comprising increasing the maximum number of simultaneously connected users in the own radio zone. 8. A threshold value of a call loss rate, a first threshold value of a communication quality degradation rate, and a second threshold value of a communication quality degradation rate smaller than the first threshold value of the communication quality degradation rate. Is set in advance, and when the calculated communication quality deterioration rate exceeds the first threshold value of the communication quality deterioration rate, the maximum number of simultaneously connected users in the own wireless zone is reduced, and the calculated call blocking rate is reduced. Increases the maximum number of simultaneously connected users in the own wireless zone when the communication quality degradation rate exceeds the threshold value of the call loss rate and the calculated communication quality degradation rate does not exceed the second threshold value of the communication quality degradation rate. 2. The call admission control method according to claim 1, wherein: 9. A mobile communication call admission control device for controlling call admission in a frequency band shared by a plurality of mobile stations communicating with a radio base station by code division multiple access, comprising: First calculating means for calculating the communication quality deterioration rate, and second calculating means for calculating the communication quality deterioration rate in the own radio zone.
Calculating means, and a third calculating means for calculating the maximum number of simultaneously connected users in the own wireless zone based on the call loss rate calculated by the first calculating means and the communication quality deterioration rate calculated by the second calculating means. A call admission control device for mobile communication, comprising: 10. The system according to claim 9, wherein the first calculating means calculates a call loss rate based on the number of outgoing calls, the number of incoming calls, and the number of incomplete calls in the own radio zone. The call admission control device according to the above. 11. The call admission control device according to claim 9, wherein said first calculating means calculates a call loss rate based on the measured number of simultaneously connected users in its own wireless zone. 12. The second calculating means calculates a communication quality degradation rate in the own radio zone based on the measured signal-to-interference power ratio of a user communicating in the own radio zone. 10. The call admission control device according to claim 9, wherein 13. The call according to claim 9, wherein said second calculating means calculates a communication quality deterioration rate in the own radio zone based on the measured interference power in the own radio zone. Reception control device. 14. When the communication quality deterioration rate calculated by the second calculation means exceeds a predetermined threshold value of the communication quality deterioration rate, the maximum number of simultaneously connected users in the own radio zone is determined. 10. The call admission control device according to claim 9, wherein the number is reduced. 15. The communication loss rate calculated by the first calculating means is greater than a preset threshold value of the call blocking rate, and the communication quality deterioration rate calculated by the second calculating means is set in advance. 10. The call admission control device according to claim 9, wherein the maximum number of simultaneously connected users in the own radio zone is increased when the communication quality degradation rate does not exceed the threshold value. 16. A threshold value for a call loss rate, a first threshold value for a communication quality degradation rate, and a second threshold value for a communication quality degradation rate smaller than the first threshold value for a communication quality degradation rate are set in advance. When the communication quality deterioration rate calculated by the second calculation means is higher than a first threshold value of the communication quality deterioration rate, the maximum number of simultaneously connected users in the own wireless zone is reduced. The call loss rate calculated by the first calculation means exceeds a threshold value of the call loss rate, and the communication quality deterioration rate calculated by the second calculation means is the second communication quality deterioration rate.
10. The call admission control device according to claim 9, wherein the maximum number of simultaneously connected users in the own radio zone is increased when the number does not exceed the threshold value.