KR100372053B1 - Method for controlling access channel overload control in a CDMA communication system - Google Patents

Abstract

The present invention variably adjusts the PSIST (Persistence) delay value according to the class of the mobile station (terminal) at the base station through an access message, thereby optimizing the radio access environment between the mobile station and the base station system, and access priority is increased according to the class of the mobile station. The present invention relates to a method for controlling access channel overload in a CDMA-type communication system, which can be allocated. The present invention detects a change in the number of use of a call channel, and when the change of the number of use of a call channel is detected, the overload control. If the minimum time has elapsed by checking whether the minimum time set by the operator has passed, the number of available communication channels of the corresponding FA is calculated, and the calculated number of available communication channels is calculated in advance. If more than one, calculate the call channel utilization of the corresponding FA. Also, the access channel overload control step is determined according to the calculated call channel utilization rate, and if the determined access channel overload control step and the previous access channel overload control step are different, the PSIST value corresponding to the determined access channel overload control step is transmitted to the mobile station. By transmitting, the channel overload can be efficiently controlled.

Description

Method for controlling access channel overload control in a CDMA communication system

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to access channel overload control at a base station of a CDMA (Code Division Multiple Access) communication system (e.g., PCS, DCS, WLL, etc.), in particular a mobile station (terminal) at a base station. In the CDMA communication system in which the PSIST (Persistence) delay value according to the class is variably adjusted through the access message, the radio access environment between the mobile station and the base station system is optimized and the access priority can be assigned according to the class of the mobile station. It relates to a connection channel overload control method.

1 is a block diagram showing the configuration of a general CDMA mobile communication system.

As shown therein, a mobile station 10 which is a terminal which a user can carry and call and data communication while moving, a base station 20 which wirelessly interfaces voice and data with the mobile station 20, and the base station 20 The control station 30 which is connected by wire and controls the base station 20, and is connected by wire with the control station 30 to switch the voice and data of the user to the other side, and to switch the other voice and data to the user side. It consists of a switch 40.

In the general CDMA mobile communication system configured as described above, the mobile station 10 and the base station 20 wirelessly interface voice and data.

Here, in order for the mobile station 10 and the base station 20 to interface voice and data wirelessly, the mobile station 10 first attempts to connect with the base station 20 through an access channel in the case of an origination. In step 20), a PN code is transmitted to the mobile station 10 through a pilot channel.

The voice and data are then interfaced through the traffic channel.

In such a general CDMA mobile communication system, a conventional base station does not perform a control function for access channel overload.

That is, the conventional base station accesses the mobile station using the PSIST delay value as it is, without considering the system situation of the base station, for example, a change in the channel environment or an overload condition.

The PSIST delay value is an access delay value according to the class of each terminal, and is classified into 16 classes (0 to 15). In more detail, the 16th grade of the terminal will be described in more detail. Grades 0 to 9 are access delay values set to general subscriber terminals, grade 10 are access delay values given to test terminals, and grade 11 are emergency subscribers. The access delay value is given to the user terminal, and the remaining 12 to 15 classes are reserved access delay values.

Therefore, as described above, the conventional base station system performs access without considering the access delay value according to the class of the terminal, and therefore, priority of a terminal having a specially assigned access class (for example, a test terminal or an emergency subscriber terminal). This had a disadvantage of being ignored.

In addition, when the amount of access increases, there is a disadvantage in that a wireless access environment between the terminal and the base station system is degraded due to the access competition of the general terminal.

Accordingly, the present invention is proposed to solve the above problems of the prior art,

SUMMARY OF THE INVENTION An object of the present invention is to optimize a wireless connection environment between a mobile station and a base station system by variably adjusting a PSIST (Persistence) delay value according to a class of a mobile station (terminal) at a base station through an access message, thereby connecting according to the class of the mobile station. An object of the present invention is to provide an access channel overload control method in a CDMA communication system in which a priority can be assigned.

The present invention for achieving the above object,

In the base station system, the Persistence Delay value of the access parameter message is differentially applied to each terminal according to the current wireless channel environment, and the access probability of the terminal is adjusted and the overload of the system is used to differentiate the service according to the class of the terminal. do. Here, the persistence delay value uses PSIST (0-9), PSIST (10), PSIST (11), PSIST (12), PSIST (13), PSIST (14), and PSIST (15) defined in an access parameter message. .

The "connection channel overload control method in a CDA communication system" according to the present invention applying this concept,

A method for controlling access channel overload in a base station in a CDMA communication system consisting of a mobile station, a base station, a control station, and a switch,

Detecting a change in the number of use of the call channel, and if it is detected that the change in the number of use of the call channel is detected, checking whether the minimum time set by the operator for the overload control has elapsed;

Calculating the number of available communication channels of the corresponding FA when the minimum time set by the operator has passed as a result of the check;

Comparing the calculated number of available communication channels with a preset minimum number of available communication channels;

Calculating a call channel utilization rate of the corresponding FA when the calculated number of available call channels is equal to or greater than a preset minimum available call channel number;

Determining an access channel overload control step according to the calculated call channel usage rate;

And comparing the determined access channel overload control step with the previous access channel overload control step, and if not, transmitting a PSIST value corresponding to the determined access channel overload control step to the mobile station. do.

1 is a block diagram showing an example of a general CDMA mobile communication system,

2 is a table schematically showing a method for controlling access channel overload according to subscriber class in the present invention;

3 is a timing diagram illustrating an access channel request attempt in the present invention.

4 is a flowchart illustrating a method of controlling access channel overload in a CDA communication system according to the present invention.

<Explanation of symbols for the main parts of the drawings>

10 ..... Mobile station

20 ..... Base Station

30 ..... Control station

40 ..... Exchange

Hereinafter, a preferred embodiment of the present invention according to the technical spirit as described above will be described in detail with reference to the accompanying drawings.

First, the present invention differentially applies a Persistence Delay value of a connection parameter message to a terminal (mobile station) in a base station, thereby controlling the access probability of the terminal, and using this to control the overload of the system and to differentiate the service according to the class of the terminal .

In order to perform the function of the efficient access channel overload control as described above, the base station of the present invention has the following additional functions.

1) Access channel overload control flag on / off function: The base station system uses the access overload control on / off flag (Access_Overload_Control_ON_OFF) to determine whether to perform the function of the access channel overload control.

2) Criteria for Determining Access Overload Control: The base station system sets the criterion for performing the access channel overload control function to the terminal by comparing the ratio of the active call channel to the available call channel of the base station system to the access channel overload control threshold value. After the comparison, it is decided whether to perform the function.

3) Access Channel Overload Control Threshold: The operator sets a threshold value for each step of the access channel overload control, and the base station system uses it as reference data when performing the corresponding function. Here, allowing the operator to set the value of the access channel overload control threshold may give flexibility to the method of optimizing for each base station system.

4) PSIST value according to each stage of access channel overload control: The operator sets PSIST0 ~ 9, PSIST10, PSIST11, PSIST12, PSIST13, PSIST14, PSIST15 value of each stage of access channel overload control, and the base station system It is used as reference data when performing. Herein, the operator may set the PSIST value according to each step of the access channel overload control, thereby providing flexibility in the optimization method for each base station system.

5) Introduction of the concept of reaction time: Paging channel overload and corresponding item of terminal due to frequent transmission parameter message transmission when performing function of access channel overload control in the situation where terminal usage in the base station system changes frequently. This may affect the performance of the system and the terminal due to the update. Therefore, the concept of reaction time for performing the connection overload control function is set to allow a certain time and this time is set as the minimum time that the access channel overload control is not performed. The minimum time interval of connection parameter message change by access channel overload control is the reaction time.

6) Minimum Number of Available Call Channels to Perform Access Channel Overload Control Function: To perform access channel overload control function, the base station system must have the minimum available call channels. This is because if connection channel overload control is performed with too small communication channel, the transmission of connection parameter messages may occur frequently. Accordingly, the base station system performs the function of access channel overload control based on the minimum number of available communication channels for performing the corresponding function set by the operator.

A preferred embodiment of the present invention will be described with reference to the characteristic functions of the base station system according to the present invention.

2 is a table schematically showing a method for controlling access channel overload according to subscriber class in the present invention.

As shown, the access class is divided into ACCLOC (0 to 9), ACCLOC (10), ACCLOC (11), ACCLOC (12 to 15), where the access class is ACCLOC (0 to 9) In this case, the control method dynamically controls a call to which the PSIST (0 to 9) value is varied and connected. If PSIST (0 to 9) is 63, it indicates that connection is impossible.

Next, when the connection class is ACCLOC (10), it indicates the test terminal class, and when the connection class is ACCLOC (11), it indicates the emergency subscriber terminal. In this case, the control method is to overload and emergency PSIST to "0". Keep it under control.

3 is a timing diagram illustrating an access channel request attempt in the present invention, where PD represents a persistence delay and RS represents a reaction time.

4 is a flowchart illustrating a method of controlling access channel overload in a CDA communication system according to the present invention.

As shown, detecting a change in the number of use of the call channel (S101), checking whether the connection overload control flag is on (S102), when the connection overload control flag is on, for overload control Checking whether the minimum time set by the operator has elapsed (S103); calculating the number of available communication channels of the corresponding FA when the minimum time set by the operator for the overload control has elapsed (S104); Comparing the calculated number of available talk channels with the minimum number of available talk channels (S105), and when the calculated number of available talk channels is greater than the minimum number of available talk channels, calculating a use rate of a call channel of the corresponding FA (S106). And determining the access channel overload control step by comparing the calculated communication channel utilization rate with the threshold values of each step set by the operator (S107). Comparing the step with the previous access channel overload control step (S108), if the determined access channel overload control step is different from the previous access channel overload control step, obtain a PSIST value corresponding to the currently determined access channel overload control step, and access And transmitting to the mobile station through the parameter message (S109), determining that the access channel overload control is performed, and setting a timer (S110).

In the method for controlling access channel overload according to the present invention, the base station system first detects whether the number of calls is changed in step S101.

As a result, when a change in the number of use of the call channel is detected, it is determined that the access channel overload control function should be performed, and it is checked in step S102 whether the access overload control flag is on.

If the connection overload control flag is on, as a result of the check, it is checked in step S103 whether the minimum time set by the operator for overload control has elapsed.

Checking whether the minimum time set by the operator has elapsed is to prevent the adverse effect on the system due to frequent access channel overload control.

Next, when the minimum time set by the operator has passed as a result of the check, the number of available communication channels of the FA is calculated in step S104.

Here, the number of available call channels refers to the number of call channels available as it is.

Next, in step S105, the calculated number of available talk channels is compared with the minimum number of available channels preset by the base station system operator. As a result, when the calculated number of available communication channels is larger than the minimum number of available communication channels, the call channel utilization rate of the corresponding FA is calculated in step S106.

Here, the call channel usage rate = (the number of the call channels in use of FA / the number of available call channels in the base station of the FA) * 100 (%).

Next, the step of access channel overload control is determined by comparing the calculated call channel utilization rate in step S107 with the threshold values of respective steps preset by the base station system operator.

For example, the access channel overload control step is divided into 10 steps according to the call channel utilization rate, and the step 10 is set as a limit for the access channel overload control when the call channel utilization rate is highest. The access channel overload control step is set by setting a limit value for the access channel overload control when the channel usage rate is lowest.

Next, in step S108, the determined access channel overload control step and the previous access channel overload control step are compared, and if not the same, move to the next step S109. This is because the access channel overload can no longer be controlled when the currently determined access channel overload control step and the previous access channel overload control step are the same.

Meanwhile, as a result of the comparison, if the access channel overload control step currently determined is different from the previous access channel overload control step, the PSIST value corresponding to the access channel overload control step currently determined in step S109 is obtained, and the PSIST value is transmitted to the mobile station through a connection parameter message. Send it.

Here, the PSIST value is set differentially corresponding to the access channel overload control step.

Next, in step S110, it is determined that the access channel overload control is performed, and sets a timer. The timer setting refers to a minimum time timer setting for preventing frequent access channel overload control from being performed.

According to the above-described "access method for overload control channel in the CD communication system" according to the present invention, the PSIST value according to the access class of the access parameter message transmitted from the base station system to the terminal to an appropriate value according to the situation of the base station system By adjusting, it is possible to give priority to call setup of an emergency terminal when an overload situation of the base station system occurs, and it is possible to reduce the amount of access messages generated by the general subscriber in advance, thereby optimizing the connection environment between the terminal and the base station.

Claims (3)

A method for controlling access channel overload in a base station in a CDMA communication system consisting of a mobile station, a base station, a control station, and a switch, Detecting a change in the number of use of the call channel, and if it is detected that the change in the number of use of the call channel is detected, checking whether the minimum time set by the operator for the overload control has elapsed; Calculating the number of available communication channels of the corresponding FA when the minimum time set by the operator has passed as a result of the check; Comparing the calculated number of available communication channels with a preset minimum number of available communication channels; Calculating a call channel utilization rate of the corresponding FA when the calculated number of available call channels is equal to or greater than a preset minimum available call channel number; Determining an access channel overload control step according to the calculated call channel usage rate; Comparing the determined access channel overload control step with the previous access channel overload control step, and if it is not the same as the result of the comparison , the PSIST value corresponding to the determined access channel overload control step is obtained, and the calculated PSIST value is used as a connection parameter message. Access channel overload control method in a CD communication system characterized in that it comprises a step of transmitting to the mobile station through . The method of claim 1, wherein the call channel utilization rate of the corresponding FA is calculated by Equation 1 as follows. (Equation 1) Call channel utilization for this FA = (number of call channels in use by FA / number of available call channels in base station by FA) * 100 (%) delete