KR20090011585A - Apparatus and method for reducing load in evolved utran node b in portable communication system - Google Patents

Abstract

An apparatus for distributing the load of a base station in a mobile communication system and a method thereof are provided to distribute the load between base stations effectively in an overlapped cell of the mobile communication system. The controller of a source base station receives the load information of neighboring base stations(601). The controller performs the process of comparing the load of the source base station with the load of the neighboring base station to check the load difference between the source base station and neighboring base station(603). If the load difference is bigger than a predetermined amount, the controller determines whether the load of the source base station is larger than that of the neighboring base station(605). If so, the controller lowers the hysteresis value of the source base station to distribute the load of a mobile communication system(607).

Description

Apparatus and method for distributing load of base station in mobile communication system {APPARATUS AND METHOD FOR REDUCING LOAD IN EVOLVED UTRAN NODE B IN PORTABLE COMMUNICATION SYSTEM}

The present invention relates to an apparatus and method for handover of a mobile communication system, and more particularly, to an apparatus and method for distributing load of a base station by adjusting hysteresis values during a handover process of a next generation mobile communication system. .

In general, a mobile communication system is a system developed to perform communication without restriction of a user's location. As the mobile communication system is able to distinguish users based on the CDMA scheme and provide a data service starting from a system focused on voice communication, users are also interested in data services.

As the interest in data services increases, users have developed and commercialized third generation mobile communication systems to provide higher data rates.

However, since a mobile communication system using the CDMA scheme has a limitation in providing a faster data service due to limited resources, various attempts have been made to provide a mobile communication service in a manner other than the CDMA scheme. One such approach is orthogonal frequency division multiple access (OFDM).

Representative technologies using the orthogonal frequency division multiple access scheme include IEEE 802.16e technology, WiBro system, and 3G Long Term Evolution (LTE) technology. In this type of system, the OFDM method can be used to transmit more data at higher speed than in the CDMA technology.

In the 3G mobile communication system, the portable terminal searches for a base station that provides a better signal when the strength of a received signal received from a base station currently connected to a communication falls below a predetermined threshold and performs a handover process.

In this case, in order to improve the stability of handover, when the signal strength of the discovered base station is greater than a predetermined value greater than the signal strength of the connected base station, the portable terminal newly connects to the discovered base station. Here, a predetermined value for determining the execution time of the handover is called a hysteresis value.

As the hysteresis value increases, the mobile terminal performs handover more conservatively. In other words, if the hysteresis value is set to a large value, since the signal strength of the discovered base station is connected to the searched base station only when the signal strength of the connected base station is sufficiently large, the handover or frequent handover may be performed due to the instantaneous channel condition change. Can be prevented.

On the other hand, despite the weak signal strength of the base station to be connected there is a risk of not being able to handover quickly. As such, the hysteresis value determines the speed and stability of the handover.

Although a handover method for a 3G LTE mobile communication system is not specifically determined at present, it is expected that a hysteresis value will be used for handover determination similarly to the 3G mobile communication system.

On the other hand, the hysteresis value was originally introduced to adjust the stability of the handover, but may also be used to adjust the load of the base station. That is, when the portable terminal has a low hysteresis value, the handover process may be performed quickly to reduce the load of the base station. When the portable terminal has a high hysteresis value, the portable terminal may increase the load of the base station by performing a late handover process.

As such, the effectiveness of equally adjusting the load between base stations by adjusting the hysteresis value was presented as a contribution at the 3GPP standardization conference. However, no specific proposal for load balancing among multiple neighboring base stations with complex situations has been presented. If the load distribution is to be carried out by simply adjusting the hysteresis value according to the load without changing the existing system or an appropriate algorithm, it does not work properly in the situation described in FIG.

1 is a diagram illustrating a process for distributing load of a base station in a general mobile communication system.

FIG. 1 (a) is a diagram illustrating a handover process of a portable terminal located between adjacent base stations having different loads.

Referring to FIG. 1A, there is a base station 120 having a large load, a base station 110 having a moderate load, a base station 130 having a small load, and the shaded cell 112 is the portable terminal. It is assumed that 100 and 102 represent cells in communication connection.

The left cell 122 is a cell of the base station 120 having a very large load, the middle cell 112 is a cell of the base station 110 having a moderate load, and the right cell 132 is a base station 130 having a small load. ) Cell.

Two portable terminals 100 and 102 connected to the base station 110 of the center cell 112 are located at the left end and the right end of the cell, and the portable terminal 100 located on the left side of the left cell 122 In order not to increase the load, it is necessary to slow down the handover process.

To this end, the hysteresis value of the center cell 112 needs to be adjusted upward. However, in the case of the right handheld terminal 102, the handover process needs to be performed more quickly for load balancing of the right cell 132, and for this purpose, the hysteresis value needs to be adjusted downward for each cell 122. There is a problem in that the load of 132 cannot be distributed.

1 (b) is a diagram illustrating a handover process of a portable terminal located between adjacent base stations having different loads.

It will be described on the assumption that there are base stations 150, 160, 170 and the portable terminal 140 having overlapping areas and different loads as shown in FIG. 1 (b).

The left cell 162 is a cell of the base station 160 having a very large load, the right cell 152 is a cell of the base station 150 having a moderate load, and the middle cell 172 is a base station 170 having a low load. ) Cell.

The portable terminal 140 connected to the base station 150 of the right cell 152 preferably performs a handover process to the center cell 172 for load balancing of the adjacent base stations 160 and 170.

However, when the base station 150 hysteresis value of the right cell 152 is adjusted downward for load balancing, the portable terminal 140 may perform a handover process to the center cell 172 but to the left cell 162. The handover process may be performed.

In other words, when the portable terminal 140 receives a stronger signal from the left cell 162 than the center cell 172, the mobile terminal 140 performs a handover process to the left cell 162, rather than the left cell 162. The problem of quickly weighting the load may occur.

The present invention has been made to solve the above problems, and to provide an apparatus and method for effectively distributing the load between base stations in the overlapping cells of the mobile communication system.

In addition, the present invention is to provide an apparatus and method that can effectively distribute the load between the base station by adjusting the hysteresis value of the base station in the mobile communication system.

According to a first aspect of the present invention, a load balancing method between base stations of a mobile communication system includes receiving load information from at least one neighboring base station, and comparing load information of the received neighboring base station with its own load information. And adjusting a hysteresis value for the adjacent base station from which the load information is received when there is a load difference greater than or equal to a predetermined reference.

As described above, the apparatus and method for distributing the load of the base station in the mobile communication system according to the present invention can effectively distribute the load between neighboring base stations by adjusting the execution time of the handover process based on the hysteresis value.

Therefore, according to the present invention, it is possible to solve the problem of increasing the load of the base station in the neighboring cell because it is not possible to check the load situation of the neighboring base station in the existing mobile communication system, and also load sharing such as an environment in which multiple cells overlap. Even in complex cell environments where it is difficult to control the load, the load can be distributed more effectively and efficiently.

Hereinafter, the operating principle of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, detailed descriptions of well-known functions or configurations will be omitted if it is determined that the detailed description of the present invention may unnecessarily obscure the subject matter of the present invention. Terms to be described later are terms defined in consideration of functions in the present invention, and may be changed according to intentions or customs of users or operators. Therefore, the definition should be made based on the contents throughout the specification.

In the following description, an apparatus and method for distributing load of a base station in a mobile communication system will be described. In addition, the hysteresis value defined in the following description refers to a value for determining a handover time. That is, in the present invention, the hysteresis value is a threshold value for determining whether or not to perform a handover process that is changed according to the load of the base station.

2 is a diagram illustrating a configuration example of a mobile communication system capable of distributing the load of a base station according to the present invention.

The mobile communication system exemplified above is a Long Term Evolution (LTE) system capable of providing a high speed data service by improving the disadvantages of low speed and high cost of data services of a third generation mobile communication system.

Referring to FIG. 2, the mobile communication system may include a portable terminal 230 and base stations 200, 210, and 220.

First, when the portable terminal 230 measures the received signal strength below the threshold, neighboring base stations are searched and notified to a base station that is connected to a service (hereinafter referred to as a "source base station").

The source base station receives load information of neighboring base stations through the X2 interface 240 to check the load of each neighboring base station, and compares the load of the source base station with the load of the neighboring base station to determine the hysteresis value of the source base station. I can adjust it. Here, the load information received from the neighbor base stations is information that can determine the load of each base station, for example, the degree of occupancy of the air resource (scaling) of each base station, scaling delay (scailing delay: from packet arrival to actual transmission) Delay), the number of UEs currently connected, the occupancy of the base station buffer, and the utilization rate of the base station processor, but this is merely an example to help understand the load information, and those skilled in the art are limited to the load information in the present invention. It will be appreciated that any base station related information that may indicate base station load may be used as load information within the scope of the present invention. In addition, these pieces of information may be used alone or in any combination as necessary to accurately represent the load of each base station.

The source base station lowers the hysteresis value of the source base station when the load of the source base station is higher than the load of the neighbor base station, and the hysteresis of the source base station when the load of the source base station is lower than the load of the neighbor base station. Adjust the value up.

The source base station obtains hysteresis values for neighboring base stations received from the portable terminal 230 and transmits the hysteresis value to the portable terminal 230.

Here, the source base station can transmit only the hysteresis value for the upper neighbor base station having a good signal strength to the portable terminal 230.

The portable terminal 230 may perform a handover process with a base station that satisfies a handover condition using the hysteresis value.

3 is a block diagram illustrating a configuration of a base station for distributing load according to the present invention.

Referring to FIG. 3, the base station 300 may be configured to include a base station controller 302, a hysteresis manager 304, and a communication unit 306.

When the controller 302 of the source base station 300 receives the information of the neighbor base station from the portable terminal, the controller 302 controls to transmit the hysteresis value of the source base station 300 for the neighbor base station to the portable terminal. .

Here, when transmitting the hysteresis value of one neighboring base station, the controller 302 may preferably use the format of a measurement control message defined in the Long Term Evolution (LTE) standard. When the hysteresis value of the neighboring base stations is transmitted, all of the hysteresis values of the neighboring base stations may be included in the measurement control message.

In addition, the control unit 302 causes the hysteresis management unit 304 to adjust the hysteresis value of the source base station 300 to distribute the load of the mobile communication system.

The hysteresis manager 304 receives the load information of the neighboring base station under the instruction of the controller 302 and checks the load of the neighboring base stations.

Thereafter, the hysteresis manager 304 compares the load of the source base station 300 with the load of the neighboring base station to adjust the hysteresis value of the source base station 300.

That is, the hysteresis management unit 304 checks the hysteresis value of the source base station 300 when the load of the source base station 300 is higher than the load of the neighboring base station under a predetermined criterion such as a unit time, a load change amount threshold, or the like. When the downlink is adjusted and it is confirmed that the load of the source base station 300 is lower than the load of the neighboring base station, the hysteresis value of the source base station 300 is adjusted upward.

The communication unit 306 performs communication with the portable terminal and receives neighbor base station information from the portable terminal according to the present invention. In addition, the hysteresis value adjusted by the hysteresis manager 304 may be transmitted to the portable terminal.

The role of the hysteresis management unit 304 may be performed by the control unit 302 of the source base station 300, but is shown separately configured in the present invention is an exemplary configuration for convenience of description and never of the present invention It is not intended to limit the scope, and one of ordinary skill in the art will recognize that various modifications are possible within the scope of the invention. For example, the controller 302 may be configured to process all of them.

The foregoing has described an apparatus for distributing the load of a base station in a mobile communication system, and in the following description, a method for distributing the load of a base station in a mobile communication system according to an embodiment of the present invention will be described.

4 is a flowchart illustrating an operation process of a portable terminal capable of distributing load of a base station in a mobile communication system according to the present invention.

Referring to FIG. 4, in step 401, the portable terminal measures signal strength (EcIo) of a pilot channel received from a base station (Source eNB: 300). Proceed to check whether the sum of the measured value and the hysteresis value Hs is equal to or less than the predetermined threshold value EcIoTH (EcIo + H <EcIoTH). At this time, it is preferable to set the Hs value relatively small in order to identify the adjacent base station of the portable terminal early.

If measuring the signal strength above the threshold, the portable terminal repeats the process of step 401.

On the other hand, when measuring the signal strength below the threshold, the portable terminal proceeds to step 405 to search for the neighbor base station, and includes the information of the searched neighbor base station in a measurement report message (Measurement Report Message) to the source The base station 300 transmits.

In step 407, the portable terminal receives one or a plurality of hysteresis values from the source base station 300. The hysteresis information may be received through a measurement control message, and includes a hysteresis value of a base station adjacent to the source base station 300.

In step 409, the portable terminal compares the signal strengths of the neighboring base station and the source base station based on the received hysteresis information.

If the signal strength of the specific neighboring base station is greater than the sum of the signal strength of the source base station and the hysteresis value for the neighboring base station as a result of the comparison in step 409, the portable terminal proceeds to step 411 and the event for the source base station is performed. Notify the information and perform a handover process with the base station.

On the other hand, if there is no neighbor base station satisfying the condition of step 409, the portable terminal proceeds to step 413 to determine whether the signal strength of the source base station is greater than a predetermined threshold value. If the preset threshold is smaller, the portable terminal returns to step 401. Otherwise, the portable terminal proceeds to step 409 and continuously compares signal strengths of neighboring base stations and source base stations.

The portable terminal then terminates this algorithm.

5 is a flowchart illustrating an operation process of a base station for distributing the load of the base station in the mobile communication system according to the present invention.

The base station of FIG. 5 will be described assuming that the hysteresis value is adjusted periodically using the load information of the neighboring base station. The process of adjusting the hysteresis value using the load information of the neighboring base station will be described in detail with reference to FIGS. 6 to 8. will be.

Referring to FIG. 5, the control unit 302 of the source eNB (hereinafter referred to as a 'source eNB') 300 first transmits a neighbor base station from a mobile station through a measurement report message in step 501. After receiving the information, the process proceeds to step 503 to select the base station having a strong signal strength of the adjacent base station of the portable terminal.

In step 505, the controller 302 transmits a hysteresis value of the selected base station to the portable terminal. In this case, the hysteresis value transmitted to the portable terminal may be a hysteresis value for one neighboring base station having the strongest signal strength among neighboring base stations, and n for the top n (n> 1) neighboring base stations according to a predetermined criterion. May be two hysteresis values.

Accordingly, the controller 302 includes a hysteresis value for one base station having the strongest signal strength or a hysteresis value for a plurality of neighboring base stations having the strongest signal strength in a measurement control message. It can transmit to the portable terminal.

6 is a flowchart illustrating a first embodiment of a hysteresis value adjusting process using load information of an adjacent base station in a mobile communication system according to the present invention.

Hereinafter, a first embodiment according to the present invention will be described with reference to FIG.

Referring to FIG. 6, the controller 302 of the base station 300 (hereinafter referred to as a source base station) 300 first receives load information of neighbor base stations in step 601. In this case, the load information may include, for example, an air resource occupancy degree of each base station, a scaling delay (delay from packet arrival to actual transmission), the number of terminals currently connected, and an occupancy degree of the base station buffer. It may be a base station processor utilization rate, but this is only an example, and those skilled in the art are not limited to the load information in the present invention, any base station related information that may indicate the base station load may be used as the load information within the scope of the present invention. It will be appreciated. In addition, these pieces of information may be used alone or in any combination as necessary to accurately represent the load of each base station.

In operation 603, the controller 302 compares the load of the source base station 300 with the load of the neighboring base station, thereby causing a load difference greater than a predetermined amount between the source base station 300 and the neighboring base station. Check if it occurs.

Step 603 is a process of determining whether a condition for adjusting the hysteresis value of the source base station 300 is satisfied by comparing the load difference between base stations under a predetermined criterion. Here, the degree of load sharing by appropriately adjusting a value corresponding to a predetermined time for comparing load magnitudes and a load difference greater than or equal to a predetermined load difference determined between the source base station 300 and a neighboring base station according to an operator's preference. Can be adjusted. For example, if the load sharing is to be done more quickly, it can be adjusted by reducing the size comparison time or lowering the load difference determination value, and the information exchange between the base stations and the hysteresis value adjustment for the load sharing are made too frequently. In the case of a heavy load, it is appropriately adjustable by increasing the above values.

If it is determined in step 603 that a load difference of a predetermined amount or more occurs between the source base station 300 and the adjacent base station, the controller 302 proceeds to step 605 in which the load of the source base station 300 is determined by the load of the adjacent base station. Determine if it is higher than the load. That is, step 605 is a step for determining whether to adjust the hysteresis value of the source base station 300 to the neighbor base station up or down to distribute the load of the mobile communication system.

If the load of the source base station 300 is higher than the load of the neighboring base station, the control unit 302 proceeds to step 607 to adjust the hysteresis value of the source base station 300 downward, thereby reducing the Try to distribute the load.

On the other hand, if the load of the source base station 300 is lower than the load of the neighboring base station, the control unit 302 proceeds to step 609 by adjusting the hysteresis value of the source base station 300, thereby increasing the Try to distribute the load.

Here, the source base station 300 may distribute the load of the mobile communication system using a plurality of hysteresis values or distribute the load of the mobile communication system using a single hysteresis value.

Other methods of the hysteresis value adjusting process using load information of neighboring base stations to distribute the load of the mobile communication system in the source base station 300 will be described in detail with reference to FIGS. 7 to 8. In addition, the source base station 300 may transmit the adjusted hysteresis value of the source base station 300 to the portable terminal.

Thereafter, the controller 302 ends the present algorithm.

7 is a flowchart illustrating another embodiment of a hysteresis value adjusting process using information of neighboring base stations in order to distribute the load of the base station in the mobile communication system according to the present invention. In the following, a second embodiment according to the present invention will be described with reference to FIG.

Referring to FIG. 7, the control unit 302 of the source eNB (hereinafter referred to as a “source base station”) 300 first receives load information from neighbor base stations in step 701.

The load information is information indicating an amount of load of the neighboring base station and may be provided from the neighboring base station through an X2 interface. Such load information may include the degree of occupancy of air resources of each base station, a scaling delay (delay from packet arrival to actual transmission), the number of terminals currently connected, the amount of occupancy of the base station buffer, and the base station processor utilization rate. This is merely an example, and one of ordinary skill in the art will appreciate that the load information in the present invention is not limited thereto, and any base station related information that may indicate the base station load may be used as the load information within the scope of the present invention. . In addition, these pieces of information may be used alone or in any combination as necessary to accurately represent the load of each base station. The controller 302 may check the load of neighboring base stations using the load information.

In operation 703, the controller 302 compares the load of the source base station 300 with the load of the neighboring base station, thereby causing a load difference greater than a predetermined amount between the source base station 300 and the neighboring base station. Check if it occurs.

Step 703 is a process of determining whether a condition for adjusting the hysteresis value of the source base station 300 is satisfied by comparing the load difference between base stations under a predetermined criterion.

If a load difference greater than a predetermined amount does not occur between the source base station 300 and the adjacent base station, the controller 302 performs the process of step 701 again.

On the other hand, when a load difference of a predetermined amount or more occurs between the source base station 300 and the adjacent base station, the controller 302 proceeds to step 705 to determine whether the load of the source base station 300 is higher than the load of the adjacent base station. Check it. Here, step 705 is a step for determining whether to adjust the hysteresis value of the source base station 300 for the neighbor base station up or down in order to distribute the load of the mobile communication system.

If the load of the source base station 300 is not higher than the neighbor base station load in step 705, that is, if the load of the source base station 300 is lower than the load of the neighbor base station, the controller 302 In operation 711, the hysteresis management unit 304 adjusts the hysteresis value of the source base station 300 with respect to the compared neighbor base stations to distribute the load of the mobile communication system.

On the other hand, when it is determined in step 705 that the load of the source base station 300 is higher than the load of the neighboring base station, the control unit 302 proceeds to step 707 and the hysteresis management unit 304 compared the neighboring base station The hysteresis value of the source base station 300 is adjusted downward to distribute the load of the mobile communication system.

The hysteresis management unit 304 received from the control unit 302 instructs the hysteresis value of the source base station 300 with respect to the adjacent base station using an algorithm such as Equation 1 and Equation 2 below. Can be adjusted.

Equation 1 is an equation that indicates that the load of the source base station 300 is lower than the load of the neighbor base station, the hysteresis value of the source base station 300 for the corresponding neighbor base station is adjusted upward.

Here, H _i is a hysteresis value of the source base station 300 for the adjacent base station i, ΔH _up is a hysteresis value that is adjusted up to reduce the load of the base station.

Equation 2 is an equation that indicates that when the load of the source base station 300 is higher than the load of the neighboring base station, the hysteresis value of the source base station 300 for the corresponding neighboring base station is adjusted downward.

]

]

Here, H _i is the hysteresis value of the source base station 300 for the adjacent base station i, ΔH _dn is a hysteresis value that is adjusted down to reduce the load of the base station.

However, the hysteresis manager 304 must adjust the hysteresis value of the source base station 300 for the adjacent base station within a range satisfying the condition as shown in Equation 3 below.

Here, H _max is the maximum hysteresis value, H _i is the hysteresis value of the source base station 300 for neighboring base station i, H _j is the hysteresis value of the source base station 300 for neighboring base station j, L _i is the neighbor base station i Where L _j is the load of neighboring base station j, H _min is the minimum hysteresis value, and N is the set of neighboring base stations.

That is, when the load of the neighboring base station i is higher than the load of the neighboring base station j, the hysteresis value for the neighboring base station i is lower than the maximum hysteresis value and higher than the hysteresis value for the neighboring base station j. In addition, the hysteresis value for the neighbor base station j should be higher than the minimum hysteresis value.

In operation 709, the controller 302 transmits the adjusted hysteresis value to the portable terminal.

Here, the controller 302 may transmit hysteresis values for the top n neighbor base stations having a signal having a good signal strength among the neighbor base stations searched by the portable terminal to the portable terminal.

The controller 302 may include the hysteresis value in a measurement control message and transmit the hysteresis value to the portable terminal, and transmits the hysteresis value for one (n = 1) upper neighboring base station having good signal strength. When transmitting, for example, it may be desirable to use a message format defined in the LTE standard.

On the other hand, when transmitting hysteresis values for a plurality of neighboring base stations having good signal strength (n> 1), for example, it may be desirable to extend the message format defined in the LTE standard.

Thereafter, the controller 302 proceeds to step 701 to repeat the process.

Through the above method, the source base station 300 can effectively perform load balancing by separately managing each hysteresis value for each neighboring base station and transmitting one or more of the most suitable hysteresis values to the portable terminal. .

8 is a flowchart illustrating a third embodiment of a hysteresis value adjusting process using information of neighboring base stations in order to distribute the load of the base station in the mobile communication system according to the present invention.

In the system according to the first embodiment described with reference to FIG. 7, the source base station manages the hysteresis value for each neighboring base station and performs load distribution by informing the portable terminal of the hysteresis value for n neighbor cells. In the second embodiment, the base station manages only a single hysteresis value, and the source base station receives load information of neighboring base stations and adjusts the hysteresis value only when it has the highest or lowest load under a certain criterion. Therefore, the hysteresis value update for load balancing is performed only at one base station of a group of adjacent base stations at a time, and load balancing is performed for all target cells through the repetition of this operation. In the present embodiment, the base station informs the terminal of the hysteresis value through the system information or the measurement control message (Measurement Control Messasge) when the terminal is handed over or camped on. When the updated hysteresis value differs by a certain level or more from the previous value through the load adjustment process as described above, the updated hysteresis value may be notified through a measurement control message to the UE (Active UE) operating in the cell. have.

Hereinafter, a third embodiment according to the present invention will be described in more detail with reference to FIG. 8.

Referring to FIG. 8, the control unit 302 of the base station 300 (hereinafter referred to as a source base station) 300 first receives load information from neighbor base stations in step 801. Here, the load information means arbitrary information or a combination of the information that can indicate the load of the base station, as already described in detail in the previous embodiments.

In operation 803, the controller 302 compares the load of the source base station 300 with the load of the neighboring base station, thereby causing a load difference greater than a predetermined amount between the source base station 300 and the neighboring base station. Check if it occurs.

Here, step 803 is a process of determining whether a condition for adjusting the hysteresis value of the source base station 300 is satisfied by comparing the load difference between base stations under a predetermined criterion.

If a load difference greater than a predetermined amount does not occur between the source base station 300 and the adjacent base station, the controller 302 performs the process of step 801 again.

On the other hand, when it is determined that a load difference of a predetermined amount or more occurs between the source base station 300 and the adjacent base station, the controller 302 proceeds to step 805 to determine whether the load of the source base station 300 is the lowest (L _i). -L> ΔL _up for ∀i∈N during T, L: load of source base station 300, L _i : load of neighboring base station).

In step 805, the hysteresis value of the source base station 300 is adjusted upward to determine whether to perform a process of distributing the load of the mobile communication system.

If it is determined that the load of the source base station 300 is the lowest, the controller 302 proceeds to step 807 to cause the hysteresis management unit 304 to adjust the hysteresis value of the source base station 300 upwards. Distribute the load of the mobile communication system.

On the other hand, if it is determined in step 805 that the load of the source base station 300 is not the lowest, the controller 302 proceeds to step 813 to determine whether the load of the source base station 300 is the highest (LL _i > ΔL). _dn for ∀i∈N during T, L: load of the source base station 300, L _i : load of the adjacent base station).

In step 813, the hysteresis value of the source base station 300 is adjusted downward to determine whether a process of distributing the load of the mobile communication system is performed.

If it is determined that the load of the source base station 300 is the highest, the control unit 302 proceeds to step 815 so that the hysteresis management unit 304 adjusts the hysteresis value of the source base station 300 downward. To distribute the load of the mobile communication system.

Here, the hysteresis management unit 304 instructed by the controller 302 may adjust the hysteresis value of the source base station 300 by using an algorithm such as Equation 4 and Equation 5 below.

Equation 4 is an equation that means that the hysteresis value of the source base station 300 is adjusted upward when the load of the source base station 300 is the lowest.

Here, H is a hysteresis value of the source base station 300, ΔH _up is a hysteresis value of the source base station 300 is adjusted up to reduce the load of the mobile communication system.

Equation 5 is an equation that means that the hysteresis value of the source base station 300 is adjusted downward when the load of the source base station 300 is the highest.

Here, H is a hysteresis value of the source base station 300, ΔH _dn is a hysteresis value of the source base station 300 that is adjusted downward to reduce the load of the mobile communication system.

However, the hysteresis manager 304 must adjust the hysteresis value of the source base station 300 within a range satisfying the condition as shown in Equation 6 below.

Here, Hmax is the maximum hysteresis value, H is the hysteresis value of the source base station 300, Hmin is the minimum hysteresis value.

That is, the hysteresis value of the source base station 300 should be adjusted within a range lower than the maximum hysteresis value and higher than the minimum hysteresis value.

In operation 809, the controller 302 determines whether a condition for transmitting hysteresis information including the hysteresis value is satisfied.

Here, the controller 302 may determine whether the transmission condition is satisfied by using an algorithm as shown in Equation 7 below.

Here, H is the current hysteresis value of the source base station 300, τ is the time when the update of the hysteresis value was last performed, H _update represents the hysteresis update threshold.

In order to determine whether the transmission condition of the hysteresis information is satisfied, the source base station 300 should store the time and the value when the hysteresis value is retransmitted to the portable terminal, and the hysteresis value is equal to the current hysteresis value and H. _{When there is an update} abnormality difference, the controller 302 may determine that the transmission condition of the hysteresis information is satisfied.

In operation 811, the controller 302 may transmit the hysteresis value to the portable terminal.

Here, the controller 302 may check the time of retransmitting the hysteresis value previously stored, and may transmit the current hysteresis value to the portable terminals that are processing the call with the source base station 300 before the retransmission time. .

Thereafter, the controller 302 ends the present algorithm.

So far, specific embodiments have been described through the detailed description of the present invention, but the scope of the present invention is not limited to these embodiments, and various modifications may be made by those skilled in the art without departing from the scope of the present invention. It will be clear. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by the equivalents of the claims.

1 is a diagram illustrating a process for distributing load of a base station in a general mobile communication system;

2 is a diagram illustrating a configuration of a mobile communication system for distributing load of a base station according to the present invention;

3 is a block diagram showing a configuration of a base station for distributing load according to the present invention;

4 is a flowchart illustrating an operation process of a portable terminal capable of distributing load of a base station in a mobile communication system according to the present invention;

5 is a flowchart illustrating an operation process of a source base station for distributing load of a base station in a mobile communication system according to the present invention;

6 is a flowchart illustrating a first embodiment of a hysteresis value adjusting process using load information of an adjacent base station in a mobile communication system according to the present invention;

7 is a flowchart illustrating a second embodiment of a hysteresis value adjusting process using load information of an adjacent base station in a mobile communication system according to the present invention;

8 is a flowchart illustrating a third embodiment of a hysteresis value adjusting process using load information of an adjacent base station in a mobile communication system according to the present invention.

Claims (1)

In the load balancing method between base stations of a mobile communication system, Receiving load information from at least one neighboring base station, Comparing the received load information of the neighboring base station with its own load information; Adjusting a hysteresis value for the adjacent base station from which the load information is received when there is a load difference greater than or equal to a predetermined reference result; Load balancing method comprising a.

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