KR100577182B1 - Method for Call Admission Control Applying to Packet Data Service - Google Patents

Abstract

The present invention provides a method for determining whether there is a margin of downlink power to be allocated to a user who has requested a call acceptance request, and when there is no margin of the power, a portion of the downlink power allocated to a user currently using packet data. Determining whether it can be allocated to the user requesting to accept the call, and if the power can be allocated as a result of the determination, whether or not to exceed the limit interference amount when accepting the call to the user who requested the call acceptance. And determining whether or not the call request can be made to the user who requested the call by reducing the amount of uplink interference by the user who is currently using the packet data. The method relates to a call admission control method of an included packet service. And to increase the number of users that can use the service, and as a result, the effect that can increase the capacity of wireless communication systems.

Call admission control, packet data service, guaranteed data rate

Description

Method for Call Admission Control Applying to Packet Data Service

1 is a flow diagram of an embodiment of a call admission control method according to the present invention;

The present invention relates to a call admission control method, and more particularly, to a call admission control method for allocating a part of resources allocated to a current packet service user to a packet service requester.

Call admission control is an algorithm that is performed to ensure the stability of the wireless system and to maintain the quality of service (QoS) of the user being serviced. In a wireless communication system using a code division multiple access (CDMA) scheme, the maximum acceptable capacity in a wireless environment is determined by interference in a wireless environment.

Accepting services beyond these wireless capacities determined at cell planning can lead to unstable operation of the wireless system as a whole and will not meet the user's required quality. Therefore, the call admission control algorithm measures the interference in the current wireless environment, predicts the amount of interference to be increased when the call is accepted for the user who has requested the call, and by the current amount of interference and the new user. If the sum of the amount of interference increased is less than the threshold in cell planning, the call is accepted or rejected.

All the wireless systems employing the CDMA method perform this operation, but especially in the wideband code division multiple access system in the present invention, this operation is a radio network controller (Radio) that manages information about a cell. It is performed by the RRM module in the Network Controller (hereinafter 'RNC').

In the second generation wireless communication system, most of the services were voice communication. From the third generation wireless communication system, various data services such as demand-based video service, e-mail, games, and the Internet are accommodated. Voice, video service and data service have different service characteristics. In particular, in time delay and guaranteed bit rate (GBR), circuit services such as voice and video services have more sensitive characteristics than packet services. That is, in the case of a packet service, if a data error rate is guaranteed, there is a characteristic that the time delay or the guaranteed data rate are not significantly limited.

In the conventional algorithm considering the packet service, the call admission control algorithm was performed in the same manner as the conventional circuit service. Call admission control is performed for uplink and downlink, respectively. In the case of downlink, the call is accepted when the condition as shown in Equation 1 is satisfied using the transmission power of the base station.

On the other hand, in the case of the uplink, the call is accepted when the condition shown in Equation 2 is satisfied using the total received power at the base station.

When a new call is attempted, the RNC receives a new call request from the Core Network (CN), which passes the quality of the new call request together. This includes sensitivity to delay, required bit rate, error rate, and so on. The call admission control algorithm receives information about the current wireless environment from the base station through total transmit power and total received power and accepts the call requested from the CN in the current situation. Check it.

In the prior art, the call admission control algorithm is performed without considering the characteristics of the packet service. For example, if 40% of the distribution of users in the system is using packet services, 60% are performing line services, and 40% of packet service users are served at the maximum bit rate. The load is at its maximum and can no longer accept new calls.

In this case, however, it is not reasonable to refuse the line service user if he or she requests to accept the call. In other words, even for some packet delays, which now occupy 40% of the wireless capacity, the required QoS can be satisfied even if the time delay and bit rate are slightly lowered. However, according to the prior art, there is a problem that the acceptance request is denied because the characteristics of the packet service are not considered in the above case.

The present invention has been proposed to solve the above problems, and is a packet service having a characteristic that is insensitive to time delay and guaranteed bit rate in a mobile communication network that accommodates various kinds of services. Is a packet service distributed on a current system in a wireless system having a packet service and a circuit service sensitive to time delay and guaranteed bit rate. It is an object of the present invention to provide a call admission control method for increasing the capacity of a system by performing call admission control (CAC) in consideration of the quantity.

In order to achieve the above object, the present invention provides a method of determining whether there is a margin of downlink power to be allocated to a user who has requested a call acceptance request, and when there is no margin of the power, a user currently using packet data. Determining whether some of the allocated downlink powers can be allocated to the user who has requested the call; and if the power is allocated as a result of the determination, accepting the call for the user who has requested the call. Determining whether or not the limit interference amount is exceeded and if the interference amount is exceeded, the amount of uplink interference by the user currently using the packet data may be reduced to allow the user to request the call to be received. Determining whether there is.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the present invention, in case of being rejected by performing call admission control in a conventional wireless communication environment, call admission control (CAC) is once again in consideration of a margin of interference reduction of a packet service. It provides a way to do this.

1 is a flowchart illustrating a call admission control method according to the present invention. As shown in FIG. 1, in the downlink call admission control method, when a call admission control request is generated, such as a new handoff radio bearer or a radio link request, the network preferentially uses code availability. Check (code availability). If no code is available, the request is ignored and the call is not accepted.

) 및 호 수락을 위한 전송 전력의 증분(

)을 계산한다. 그리고, 다음 수학식 3 및 수학식 4 를 만족하는지를 판단한다.If the code availability is satisfied, a downlink bit rate that satisfies the required Quality of Service (QoS) is calculated, and signal-to-noise (Eb / No) mapping is performed. The downlink signal-to-noise ratio (Eb / No) is calculated from the mapping table. Current transmit power (

) And the increment of transmit power for call acceptance (

Calculate Then, it is determined whether the following equations (3) and (4) are satisfied.

은 전체 전력의 증분을 나타내고,

은 미리 정해 놓은 전체 전력 증분의 상한값을 의미한다.In Equation 3

Represents an increment of total power,

Denotes a predetermined upper limit of the total power increment.

은 현재의 전송 전력을 나타내고,

은 호 수락을 위한 전송 전력의 증분을 의미한다. 한편,

은 미리 정해 놓은 전체 전력의 상한값을 의미하고,

는 핸드오프 마진 전력을 의미한다. In Equation 4

Represents the current transmit power,

Denotes the increment of transmit power for call acceptance. Meanwhile,

Means a predetermined upper limit of total power,

Means handoff margin power.

If the above Equations 3 and 4 are satisfied, the uplink condition necessary for accepting the call is determined.

On the other hand, when the equations 3 and 4 do not satisfy, it is determined whether the following equations 5 and 6 are satisfied.

은 현재의 전송 전력의 증분을 나타내고,

는 미리 정해 놓은 전송 전력 증분의 상한값을 의미한다. 한편, 수학식 6 에서

는 현재의 전송 전력을 나타내고,

은 현재의 전송 전력의 증분을 나타내며,

는 미리 정해 놓은 전송 전력의 상한값을 의미한다. In Equation 5

Represents the increment of the current transmit power,

Denotes an upper limit of a predetermined transmission power increment. Meanwhile, in Equation 6

Represents the current transmit power,

Represents the increment of the current transmit power,

Denotes an upper limit of a predetermined transmission power.

If the equations 5 and 6 are satisfied, the uplink condition necessary for accepting the call is determined.

When the equations 5 and 6 are not satisfied, it is determined whether the following equation 7 is satisfied.

The value of ω in Equation 7 is determined in consideration of the current bit rate versus the maximum bit rate and the actual time delay that is actually acceptable in view of the characteristics of each service.

In Equation 7, the left side is an amount extracted from the QoS of the newly requested call, where Eb / No is a required signal-to-noise ratio, R is a bit rate, and v is an activity factor. The right hand side is the values extracted from each user's QoS for all the packet service user numbers P currently accepted by the system. W represents a chip rate, and ω represents a weight previously designated by the operator.

If the condition described in Equation 7 is satisfied, the new call is accepted and the transmission power corresponding to the new call is obtained by adjusting the bit rate of the existing packet service user in the packet scheduler. This assumes that all packet service users have the same propagation gain.

First of all, it is necessary to know the amount of wireless capacity of the packet service user. Here, consider the percentage of how much the current bit rate of the Packet service user is compared to the maximum bit rate. This is because if the current bit rate is too low for the maximum bit rate, the delay becomes too large. In the case of a WCDMA system, there is no time delay threshold in the case of a web-based service, but if the response of the web service is delayed for more than a few seconds from the user's point of view, dissatisfaction with the service will increase.

If the condition described in Equation 7 is not satisfied, the requested bit rate is lowered, and if the lowered bit rate is greater than the upper bit rate upper limit, the link signal-to-link signal from the forward link signal to noise ratio (Eb / No) mapping table is The above steps are performed again from the step of calculating the noise ratio Eb / No.

Meanwhile, if the lowered bit rate is less than or equal to the upper limit of the bit rate, the uplink conditions necessary for call acceptance are determined as follows.

Calculate an uplink bit rate that can satisfy the requested Quality of Service (QoS) and downlink signal-to-noise ratio from the signal-to-noise (Eb / No) mapping table. Calculate (Eb / No).

) 및 호 수락을 위한 간섭량의 증분(

)을 계산하고, 다음 수학식 8 을 만족하는지 판단하여 조건을 만족하면 호를 수락한다. Current amount of interference (

) And the increment of the amount of interference to accept the call (

), Determine if the following Equation 8 is satisfied, and if the condition is satisfied, accept the call.

은 현재의 간섭량을 나타내고,

은 호 수락을 위한 간섭량의 증분을 의미한다. 한편,

은 미리 정해놓은 전체 간섭량의 상한값을 의미한다. 상기 수학식 8 을 만족하지 않는 경우에는 다음 수학식 9 를 판단한다. In Equation 8

Denotes the current amount of interference,

Means the increment of interference for call acceptance. Meanwhile,

Denotes an upper limit of the total amount of interference predetermined. If the above Equation 8 is not satisfied, the following Equation 9 is determined.

은 현재의 간섭량을 나타내고,

은 호 수락을 위한 간섭량의 증분을 의미한다. 한편,

은 미리 정해 놓은 전체 간섭량의 상한값을 의미하고,

는 핸드오프 마진 전력을 의미한다. 상기 수학식 9 를 판단한 결과 만족하는 경우에는 호를 수락한다. In Equation 8

Denotes the current amount of interference,

Means the increment of interference for call acceptance. Meanwhile,

Means the upper limit of the predetermined total interference amount,

Means handoff margin power. If the result of the determination of Equation 9 is satisfied, the call is accepted.

When the equation 9 is not satisfied, it is determined whether the following equation 10 is satisfied.

는 요구되는 신호대 잡음비 이다. 우변은 현재 시스템에서 수용하고 있는 모든 패킷 서비스 사용자 클래스 P 에 대해 각 서비스 클래스의 사용자 수 M 과 각 서비스 클래스의 요구되는 신호대 잡음비를 사용한다. In Equation 10, the left side is a value extracted from the QoS of a newly requested call.

Is the required signal-to-noise ratio. The right side uses the number of users M of each service class and the required signal-to-noise ratio of each service class for all packet service user classes P currently accepted by the system.

In Equation 10, the value of ω is determined by considering the current bit rate versus the maximum bit rate and the actual time delay that is actually acceptable in view of characteristics of each service.

If the equation 10 is satisfied, the call is accepted. If not, the requested bit rate is lowered. If the lower bit rate is greater than the upper limit of the bit rate, the forward link signal to noise ratio (Eb / No) mapping is performed. The above steps are performed again from the step of calculating the link signal-to-noise ratio (Eb / No) from the table. If the call is accepted in this process, it is necessary to lower the bit rate of the existing packet service user to make a margin of interference to accommodate the new user. This process is handled by the packet scheduler.

If the call is accepted, the bit rate of the existing packet service user should be lowered to make an amount of interference to accommodate the new user. This process is handled by the packet scheduler.

As described above, the method of the present invention may be implemented as a program and stored in a recording medium (CD-ROM, RAM, floppy disk, hard disk, magneto-optical disk, etc.) in a computer-readable form. Since this process can be easily carried out by those skilled in the art will not be described in detail any more.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by the drawings.

As described above, the present invention can increase the number of users who can use the packet service, and as a result, the capacity of the wireless communication system can be increased.

Claims (3)

Determining whether there is a margin of downlink power to be allocated to a user who has requested a call acceptance request; Determining whether a portion of the downlink power allocated to the user currently using the packet data can be allocated to the user requesting to accept the call when there is no margin of the power; Determining whether the amount of interference is exceeded when accepting a call for the user who has requested to accept the call when the power is allocated as a result of the determination; And If the amount of interference is exceeded as a result of the determination, determining whether or not the user can request call acceptance by reducing the amount of uplink interference by the user currently using the packet data. Call admission control method of a packet service comprising a. The method of claim 1, Determining whether a portion of the downlink power can be allocated to the user requesting to accept the call,

And a part of downlink power is allocated to a user who has requested call acceptance when the call is satisfied. Where p is the number of all packet service users, v is the activity factor, Eb / No is the signal-to-noise ratio due to the quality of service (QoS) of the call, W is the chip rate, and R is The bit rate, ω, represents a weight previously specified by the operator.) The method of claim 1, Reducing the amount of uplink interference to determine whether the user can request the call to accept the call,

And if it satisfies the method, reducing the amount of uplink interference and accepting the call for the user who has requested the call. (only,

Is the signal-to-noise ratio, ω is the weight predefined by the operator, P is the user class, and M is the number of users.)

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