KR101579753B1 - Method and system for performing handover to achieve load-balancing in wireless communication system - Google Patents

Abstract

A method for performing a handover of a base station for load balancing in a wireless communication system of the present invention includes a handover capable terminal discrimination step of discriminating terminals located in a handover enabled area among terminals included in a source cell, A filtering step of filtering the terminals having the possibility of reverse handover among the terminals determined to be located in the handover-enabled area, and a step of filtering the terminals that are not located in the handover- And a handover execution step of performing handover of the unfiltered terminals to the selected target cell according to the priority order.

According to the present invention, it is possible to effectively manage the load imposed on the cell by reducing the additional overhead that occurs in order to perform load balancing. Further, according to the present invention, it is possible to solve the problem that the load is further increased in a cell having a high load.

Load equalization, power control

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a handover method for performing load balancing in a wireless communication system, and a system for performing load balancing in a wireless communication system.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless communication system, and more particularly, to a method for load balancing between base stations in a wireless communication system and a system therefor.

The Universal Mobile Telecommunication Service (UMTS) system is based on Global System for Mobile Communications (GSM) and General Packet Radio Services (GPRS), which are European mobile communication systems, and includes a Wideband Code Division Multiple Access WCDMA) is used as the third-generation asynchronous mobile communication system.

In the 3rd Generation Partnership Project (3GPP), which is in charge of standardization of UMTS, a discussion on LTE (Long Term Evolution) is underway as a next generation mobile communication system of UMTS system. LTE is a technology that implements high-speed packet-based communication with transmission speeds of up to 300 Mbps and aims to commercialize it in about 2010. Various schemes are discussed for this purpose. For example, there are discussions such as reducing the number of nodes located on the communication path by simplifying the structure of the network, and approaching wireless protocols to a wireless channel as much as possible.

On the other hand, in the LTE system, when a load of one cell is increased, a method of connecting a part of terminals connected to a current cell to a neighboring cell is used as a method for reducing the load of the corresponding cell. To this end, a load balancing method using power control that controls the physical coverage of the cell by physically controlling the uplink / downlink power has been proposed. However, according to the load balancing method using the power control, if the power is adjusted to control the terminal located in the overlapped area with the neighboring cell, it is possible to affect the neighboring terminals .

Also, by sending an RRC message to all active terminals, which are conventionally connected to an RRC (Radio Resource Control) connection, in order to determine a terminal to be a target of the load balancing method, that is, a terminal located at the edge of cell coverage, Is proposed. However, according to this scheme, the RRC message must be transmitted to all the active UEs through the dedicated channel, thereby increasing the overhead for the base station.

A method and a system for performing a handover of a base station for load balancing in a wireless communication system according to the present invention aim at effectively performing load balancing between base stations while minimizing the additional overhead of the base station and the base station. In addition, a method and system for load balancing among base stations in a wireless communication system according to the present invention reduces the overhead between a terminal and a base station, which is additionally generated in order to identify a terminal located in a handover enabled area, And to reduce the load due to the measuring operation to be performed.

In order to solve the above problems, a method of performing a handover of a base station for load balancing in a wireless communication system according to the present invention includes a handover-capable terminal discrimination step of discriminating terminals located in a handover- A cell selecting step of selecting a target cell according to an overload type, a filtering step of filtering terminals having a possibility of reverse handover among terminals determined to be located in the handover enabled area, And a handover execution step of performing handover of the unfiltered terminals to the selected target cell according to the priority order. . In addition, the step of determining a handover-capable terminal may further comprise the step of determining a possibility of being located in the handoverable area among the terminals included in the source cell, using a Channel Quality Indicator (CQI) of the terminals included in the source cell The method comprising the steps of: selecting terminals, monitoring a load status, controlling the selected terminals to determine whether they are located in the handover enabled area if the load status exceeds a threshold value, Transmitting a report message to the base station when the mobile station is located in the handover-enabled area, and determining the terminals that have transmitted the report message to be located in the handover-enabled area.

Determining whether the selected target cell is a cell that was determined to be located in the handover-enabled region and which was accessed immediately before connecting to the source cell; Determining whether handover from the target cell to the source cell is due to load equalization if the handover is determined to be a cell, and determining whether handover from the target cell to the source cell is due to load balancing if the handover is due to load equalization, Wherein the handover is not performed.

In order to solve the above problems, a wireless communication system according to the present invention includes a base station controlling a source cell and terminals included in the source cell, the base station including: Selecting a target cell according to an overload type of the base station, filtering terminals having a possibility of reverse handover among terminals located in the handover enabled area, Handover priority of the unfiltered terminals is determined and the unfiltered terminals are handed over to the selected target cell according to the priority to perform load equalization. In addition, the BS selects a UE having a high possibility of being located in the handover-available region among the UEs included in the source cell using a channel quality indicator (CQI) of the UEs included in the source cell, The mobile terminal monitors its load status and controls the selected terminals to determine whether the mobile terminal is located in the handover enabled area when the load status exceeds a threshold value, The selected UEs determine whether the selected UEs are located in the handover enabled area, and transmit the reporting message to the BS when the UEs are located in the handover enabled area.

Further, the base station determines whether the selected target cell is a cell that was determined to be located in the handover-enabled region immediately before accessing the source cell, and determines that the target cell is a cell that was accessed immediately before Handover from the target cell to the source cell is due to load equalization, and if the handover is due to load balancing, the handover of the UE determined to be located in the handover-enabled area is performed .

According to the handover method of the base station for load balancing in the wireless communication system of the present invention and the system therefor, it is possible to efficiently manage the load imposed on the cell by reducing the additional overhead generated for performing load balancing . In addition, according to the method and apparatus for load balancing among base stations in the wireless communication system of the present invention, it is possible to solve the problem of additionally increasing load on a cell having a high load.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the same components are denoted by the same reference numerals as possible in the accompanying drawings. Further, the detailed description of well-known functions and constructions that may obscure the gist of the present invention will be omitted.

Also, the terms and words used in the present specification and claims should not be construed to be limited to ordinary or dictionary meanings, and the inventor is not limited to the concept of terms in order to describe his invention in the best way. It should be construed in accordance with the meaning and concept consistent with the technical idea of the present invention based on the principle that it can be properly defined.

It is also assumed that the terminology of the embodiment of the present invention conforms to the 3GPP LTE system standard.

1 is a diagram illustrating a schematic structure of a wireless communication system according to an embodiment of the present invention.

Referring to FIG. 1, in a wireless communication system according to an embodiment of the present invention, an Evolved Radio Access Network (E-RAN) 110 and 112 includes an evolved Node B (ENB) 120 , 122, 124, 126, and 128, and an EPC (Evolved Packet Core) 130 and 132.

The UE (User Equipment) 101 connects to the IP (Internet Protocol) network 114 by the E-RANs 110 and 112. The ENBs 120, 122, 124, 126 and 128 are connected to the user UE 101 via a radio channel as nodes corresponding to the existing Node Bs. In order to realize a transmission rate of up to 300 Mbps, the wireless communication system uses Orthogonal Frequency Division Multiplexing (OFDM) as a radio access technology in a 20 MHz bandwidth. And Adaptive Modulation and Coding (AMC), which determines a modulation scheme and a channel coding rate according to channel conditions, is applied.

Hereinafter, the E-RANs 110 and 112 including the ENBs 120, 122, 124, 126 and 128 and the EPCs 130 and 132 are referred to as base stations, and the UE 101 is referred to as a UE.

2 is a view conceptually showing a method of controlling cell coverage through power control and performing load balancing through the control of cell coverage.

Referring to FIG. 2, in order to reduce the load on the base station 201 responsible for the cell when the load on the base station 201 responsible for one cell increases, generally, power control is used A load equalization method is used. In order to connect the terminals 203, 203 and 204 connected to the base station 201 responsible for the cell to the base station 202 responsible for the neighboring cell, the uplink / downlink And controls the physical coverage of the cell served by the base stations 201 and 202 by controlling the power.

In applying the load equalization method, it is necessary to detect a terminal to be connected to the base station 202 that is in charge of the neighboring cell, that is, a terminal to be handed over. For this, the terminal located at the edge of cell coverage should be identified. When the load to be handled by the base station 201 is constant, handover must be performed to perform load balancing. In order to identify the terminals 204 and 205 located in the handover enabled area, RRC reconfiguration signaling (203, 204, 205) in the corresponding cell through a corresponding cell (e.g. All the active terminals in the corresponding cell receiving the RRC reset message perform measurements on the surrounding cells and report whether the terminal is located at the edge of the cell based on the new criteria. Here, the "handover enabled area" defined by the newly received parameter represents a larger area than the existing handover area.

However, according to the load balancing method using the power control, if the power is adjusted to control the terminal located in the overlapped area with the neighboring cell, it is possible to affect the neighboring terminals .

Also, since the RRC messages are transmitted to all the active terminals through the dedicated channel in the process of selecting the terminals used for the load balancing, the overhead of processing by the base station increases. If the overhead due to the additional procedure is large, the load of the base station may increase rather than load balancing even though the base station whose load has already exceeded a predetermined level performs load balancing to efficiently distribute it. There is a problem that it is possible.

In order to solve this problem, a handover-based load equalization technique is proposed in which handover is performed ahead of time by discriminating a terminal located in a "handover enabled area " without changing the physical power. Specifically, in order to perform the load equalization technique, the base station determines and handles the handover of the terminals located in the handover region. To do this, we propose a method of 1) identifying terminals located in a handoverable area, and 2) a method of determining priority of terminals to be handed over based on resource usage patterns among available terminals.

FIG. 3 is a diagram illustrating a comparison between a handover area and a handover enabled area according to an embodiment of the present invention.

Referring to FIG. 3, the handover area 301 refers to an area in which a handover event is executed according to existing handover measurement setting parameters.

On the other hand, the handover enabled area 302 refers to an area where the strength of a signal transmitted from a base station controlling a neighbor cell is strong enough to enable handover, and is defined by newly received parameters. Also, the handover enabled area 302 defined by the newly received parameter is generally a wider area than the handover area 301.

Hereinafter, the following three methods are proposed to identify the terminals located in the handover enabled area. Second, it is a technique to measure and report whether a handover-enabled area is received only when a load equalization measurement indicator is received through a broadcast channel. Finally, It is a technique to measure and report whether a handover is possible based on a channel quality indicator (CQI).

FIG. 4 is a flowchart illustrating a method for determining terminals located in a handover-enabled area according to an embodiment of the present invention. In particular, the method of determining the terminals located in the handover-enabled area of FIG. 4 uses a technique of measuring and reporting whether the handover-enabled area is periodically described above.

Referring to FIG. 4, in step 401, a mobile station operating in an idle state transmits an RRC connection message to a base station. The base station, which has received the RRC connection message, sets the measurement parameters in step 402. When each terminal changes its operation mode to an active state by performing an RRC connection in an idle state, the base station transmits an RRC re-establishment message to the terminal in step 403. In the present invention, the RRC reset message includes the measurement parameters set in step 402.

More specifically, the above measurement parameter is a combination of a period and an event generation condition, that is, whether or not the event generation condition is located in a handover enabled area. When the terminal satisfies an event generation condition every cycle, And if it is satisfied, report to the base station. In other words, it is determined whether the event generation condition is measured at the set period in step 404, that is, whether the event generation condition is located in the handover enabled area. If the event generation condition is unsatisfactory, the event generation condition is re- . If it is determined in step 406 that the event occurrence condition is satisfied, the UE transmits a measurement report message to the base station in step 407.

In step 408, the BS proceeds to a handover process of setting priority levels of the MSs to which handover will be performed among the MSs transmitting the measurement report message. Step 408 will be described in detail later.

In this method, unlike the conventional method, there is no need to additionally transmit the RRC message to the UE that has already been changed to the active mode, thereby reducing the load on the base station and the UE. Regardless of the load status of the base station, each terminal reports measurement results to the base station based on the additional measurement parameters received at the time of RRC connection. That is, even if the load of the base station is low, the terminal located in the handover-enabled area may have a disadvantage of reporting the measurement. However, in order to reduce the uplink measurement load of the UE, the present invention can solve the problem by setting the period to be relatively longer than the period in which the handover event occurs.

5 is a flowchart illustrating a method of determining terminals located in a handover-enabled area according to another embodiment of the present invention. In particular, the method of determining the terminals located in the handover-enabled area of FIG. 4 uses a technique of measuring and reporting whether or not the load-equalization measurement indicator is a handover-enabled area only when the load balancing measurement indicator is received through a broadcast channel.

Referring to FIG. 5, in step 501, a mobile station operating in an idle state transmits an RRC connection message to a base station. Upon receiving the RRC connection message, the base station sets a measurement parameter in step 502. When each terminal changes its operation mode to the active state by performing the RRC connection in the idle state, the base station transmits an RRC reset message to the terminal in step 503. This RRC reset message contains the measurement parameters set in step 502. [

In step 504, the base station monitors the load condition and checks whether the load exceeds the threshold. If the load exceeds the threshold, the base station transmits to the terminal a SIB broadcast message including a measurement indicator, which is an instruction to measure whether or not the base station is located in a handover enabled area in the next SIB (System Information Block) period in step 505.

Subsequently, in step 506, the UE performs measurement, and in step 507, it is determined whether or not the event occurrence condition is satisfied as a result of performing the measurement, that is, whether or not the UE is located in the handover-enabled area. If the event occurrence condition is satisfied, the terminal transmits a measurement report message to the base station in step 508.

In step 509, the base station selects a terminal to perform a handover among the terminals that transmitted the measurement report message or sets a priority to proceed with the handover. Step 509 will be described later in detail.

The method of FIG. 5 is similar to the method of FIG. 4 but differs in that measurement is performed only when a measurement indicator is received from a base station through a broadcast channel, instead of periodically measuring and reporting. That is, when the RRC connection of the UE in the idle state is established, the UE receives the measurement related parameter in advance. Therefore, the UE measures whether it is located in the handover-enabled area only when it receives the measurement indicator from the BS through the broadcast channel. In the existing LTE system, since the active terminal periodically reads the SIB from the broadcast channel, it can be implemented by adding a measurement execution related field to the existing SIB message.

FIG. 6 is a flowchart illustrating a method of determining terminals located in a handover-enabled area according to another embodiment of the present invention. In particular, the method of determining terminals located in the handover-enabled area of FIG. 6 uses a technique of measuring and reporting whether or not a handover-enabled area is based on the above-described Channel Quality Indicator (CQI).

Referring to FIG. 6, in step 601, the BS selects a group of UEs based on a channel quality indicator. More specifically, the base station selects a group of terminals having a high possibility of being located in the handover-enabled area based on the channel quality indicator among all the terminals to be controlled. Also in step 602, the base station monitors the load condition and checks whether the load exceeds the threshold. If the load exceeds the threshold, the base station transmits an RRC reset message requesting a measurement to determine whether it is located in the handover-enabled area as a group of selected terminals, in step 603, via a dedicated channel.

Subsequently, in step 604, the UE performs the measurement and, as a result of performing the measurement in step 605, determines the event generation condition, i.e., whether the UE is located in the handover-enabled area. If the event occurrence condition is satisfied, the UE transmits a measurement report message to the BS in step 606.

In step 607, the base station selects a terminal to perform a handover among the terminals that transmitted the measurement report message or sets a priority, and proceeds with the handover. Step 607 will be described later in detail.

Such a scheme is similar to the conventional scheme, but when the load is close to a certain threshold, it is not requested to report to all the UEs of the corresponding cell but requests priority to report to UEs likely to be located in the handover enabled area It is a point. Through this technique, it is possible to reduce the excessive overhead incurred when receiving RRC messages to all UEs. In addition, it has an advantage that it can be applied without changing the standard specification as compared with the technique described in FIG. 4 and FIG.

Hereinafter, a method of selecting a UE to which a handover will be performed among the UEs transmitting the measurement report message, setting a priority, and performing a handover will be described. The priority setting method of the present invention is performed in three steps. First, a filtering operation is performed to prevent ping-pong occurring due to load equalization among terminals located in a handover enabled area. Second, the priorities of the terminals to be handed over are set in consideration of the resource usage pattern of the terminal, the load type of the base station controlling the cell, and the load level among the terminals remaining after the filtering. Finally, the target cell of the handover is selected considering the load of the base stations controlling neighboring cells. Each step is described in more detail below.

7 is a flowchart illustrating a handover procedure for performing load balancing according to an embodiment of the present invention.

Referring to FIG. 7, in step 701, the base station transmits a handover preparation message to surrounding cells to perform handover for load balancing. In step 702, the base station receives an ACK message from neighboring cells, and selects a target cell for performing an actual handover among neighboring cells that transmitted an ACK message in step 703. Hereinafter, a process of selecting a target cell will be described in detail.

If the base station controlling the cell to start the handover for load balancing is trying to equalize the load due to hardware overload, a hardware overload of the base stations controlling the neighboring cells that transmit the ACK message The target cell is selected by determining the priority in ascending order.

Also, if the base station controlling the source cell attempts to load equalize due to an overload in the uplink transmission resources, the base station controlling the source cell can not allocate priority And selects a target cell. Similarly, if the base station controlling the source cell attempts to load equalize due to an overload in the downlink transmission resources, the base station controlling the source cell can not allocate priority And selects a target cell.

On the other hand, when the UE is handed over by load balancing, there is a high possibility that the UE performs a reverse handover to the previous source cell in the target cell. This is because the measurement parameter value of the terminal related to the handover execution of the target cell is not synchronized with the load equalization operation of the source cell. In order to prevent ping-pong due to such load balancing, a filtering technique such as steps 704 to 706 is performed.

Specifically, the BS determines in step 704 whether the selected target cell of the UEs located in the handover-enabled area is a source cell that was accessed immediately before. Also, it is determined in step 704 that the target cell of the handover is the source cell that was connected immediately before. In step 705, the base station determines whether the residence time connected to the current source cell is shorter than the threshold time. The threshold time is a value that can be arbitrarily set according to a system and a channel environment by a person having ordinary knowledge in the art to which the present invention belongs.

If it is determined in step 705 that the residence time is shorter than the threshold time. In step 706, the base station determines whether the previous handover reason was a handover for load balancing. If it is determined in step 706 that the previous handover reason is a handover for load balancing, the base station ignores the handover event for that terminal in step 707. That is, filtering is performed to prevent ping-pong due to load equalization.

On the other hand, if it is determined in step 704 that the target cell is not the immediately preceding cell, in step 705, it is determined that the residence time connected to the current source cell is longer than the threshold time, and in step 706, If it is determined that the handover is not performed for load balancing, the handover priority order of the terminals belonging to the handover-enabled area that is not filtered in step 708 is determined. Hereinafter, a method for determining the handover priority order will be described in detail.

The UEs satisfying the existing handover initiation determination conditions are selected as the terminals to be handed over first regardless of the load balancing among the UEs belonging to the handover enabled areas that are not filtered.

을 결정하고, 그 크기에 따라 우선순위를 결정할 수 있다.On the other hand, terminals that do not satisfy the existing handover initiation decision conditions determine the priority according to the type of the overload, and also select a set number of terminals to be handed over. For example,

And determine the priority according to the size.

≪ Equation &

은 단말의 UL(UpLink) 자원 사용량, DL(DownLink) 자원 사용량, TNL(Transport Network Layer) 자원 사용량 및 HW 자원 사용량 등을 종합하여 결정되며, 특히

을 계산함에 있어, 가중치

은 기지국의 과부하가 어떤 종류의 과부하인지 여부에 따라 당업자에 의하여 임의로 설정될 수 있음은 자명하다. In particular,

Is determined based on a combination of UL (Uplink) resource usage, DL (Downlink) resource usage, TNL (Transport Network Layer) resource usage, HW resource usage,

In calculating the weight,

Can be arbitrarily set by a person skilled in the art depending on whether the overload of the base station is an overload of some kind or not.

Finally, in step 709, the BS proceeds to handover to the target cell selected in step 703 according to the priority of the UEs determined in step 706 and the number of UEs to be handed over to perform load balancing.

It should be noted that the embodiments of the present invention disclosed in the present specification and drawings are only illustrative examples of the present invention and are not intended to limit the scope of the present invention in order to facilitate understanding of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

1 shows a schematic structure of a wireless communication system according to an embodiment of the present invention;

2 conceptually illustrates a method of controlling cell coverage through power control and performing load balancing through it.

3 illustrates a comparison between a handover area and a handover-enabled area according to an embodiment of the present invention.

4 is a flowchart illustrating a method of determining terminals located in a handover-enabled area according to an embodiment of the present invention.

5 is a flowchart illustrating a method of determining terminals located in a handover-enabled area according to another embodiment of the present invention.

FIG. 6 is a flowchart illustrating a method for determining terminals located in a handover-enabled area according to another embodiment of the present invention; FIG.

7 is a flowchart illustrating a handover procedure for performing load balancing according to an embodiment of the present invention;

Claims (14)

A method for performing handover of a base station in a wireless communication system, Transmitting to the at least one terminal a measurement parameter for determining whether at least one terminal included in the source cell is located in a handover-enabled area; Receiving a measurement report message generated from the at least one terminal using the measurement parameter, and determining whether the at least one terminal is located in the handover-enabled area; Filtering a terminal having a possibility of reverse handover among at least one terminal transmitting the measurement report message; Selecting a target cell; And Handing over at least one unfiltered terminal to the selected target cell as a result of the filtering; And performing a handover of the base station. The method according to claim 1, Determining a load of the base station; Transmitting a SIB (System Information Block) broadcast message including an indicator for instructing the UE to measure whether the UE is located in the handover-enabled area when the load exceeds a threshold value; ; Further comprising: Wherein the determining step comprises: Receiving the measurement report message from at least one terminal that has received the SIB broadcast message and determining whether the at least one terminal is located in the handover enabled area. The method according to claim 1, (CQI) received from at least one terminal included in the source cell, based on a channel quality indicator (CQI) received from at least one terminal included in the source cell, ; And Determining a load of the base station; Further comprising: Wherein the determining step comprises: Receiving the measurement report message from the selected at least one terminal and determining whether the at least one terminal is located in the handover enabled area. The method according to claim 1, Wherein the determining step comprises: Receiving the measurement report message from the at least one terminal every predetermined period, and determining whether the at least one terminal is located in the handover-enabled area. The method according to claim 1, Wherein the filtering comprises: Determining whether the selected target cell is a cell that was determined to be located in the handover-enabled region and which was accessed immediately before connecting to the source cell; Determining whether a connection holding time of the terminal connected to the source cell is shorter than a threshold time when it is determined that the target cell is a cell immediately before the connection; Determining whether handover from the target cell to the source cell is due to load equalization if the connection holding time is shorter than the threshold time; And Performing handover to the target cell for a terminal determined to be located in the handover-enabled area if the handover is due to load balancing; Further comprising the step of: The method according to claim 1, Wherein the handover- Wherein a strength of a signal transmitted from a base station controlling a cell adjacent to the source cell is greater than or equal to a strength of a signal transmitted from a base station controlling the source cell in the source cell. A base station of a wireless communication system, The method comprising: transmitting, to the at least one terminal, a measurement parameter for determining whether at least one terminal included in the source cell is located in a handover enabled area, A transmission / reception unit for receiving a message; Determining whether the at least one UE is located in the handover-enabled region using the received measurement report message, filtering the UE having a possibility of reverse handover among at least one UE transmitting the measurement report message, A control unit for selecting a target cell and handing over at least one unfiltered terminal to the selected target cell as a result of the filtering; / RTI > 8. The method of claim 7, Wherein, An SIB (System Information Block) including an indicator for determining a load of the base station and instructing the mobile station to measure whether the mobile station is located in the handover enabled area when the load exceeds a threshold value, Receiving a measurement report message from at least one terminal that has received the SIB broadcast message through the transceiver and determining whether the at least one terminal is located in the handover enabled area To the base station. 8. The method of claim 7, Wherein, (CQI) received from at least one terminal included in the source cell, based on a channel quality indicator (CQI) received from at least one terminal included in the source cell, Wherein the base station determines the load of the base station and receives the measurement report message from the selected at least one terminal to determine whether the at least one terminal is located in the handover enabled area, . 8. The method of claim 7, Wherein, Wherein the base station receives the measurement report message from the at least one terminal at a predetermined interval and determines whether the at least one terminal is located in the handover-enabled area. 8. The method of claim 7, Wherein, Determining whether the selected target cell is a cell that was determined to be located in the handover-enabled region and which was accessed immediately before the source cell is connected to the source cell; Determining whether a connection holding time of the terminal connected to the source cell is shorter than a threshold time and whether the handover from the target cell to the source cell is due to load equalization if the connection holding time is shorter than the threshold time And performs control to not perform handover to the target cell for a terminal determined to be located in the handover-enabled area when the handover is due to load equalization. 8. The method of claim 7, Wherein the handover- Wherein a strength of a signal transmitted from a base station controlling a cell adjacent to the source cell is greater than a strength of a signal transmitted from a base station controlling the source cell in the source cell. A method of handover of a terminal in a wireless communication system, Receiving from the base station a measurement parameter for determining whether the base station is located in a handover enabled area; Determining whether the UE is located in the handover-enabled region using the received measurement parameter, generating a measurement report message including the determination result, and transmitting the generated measurement report message to the BS ; And Performing a handover to a selected target cell according to a filtering result of filtering a terminal having a possibility of reverse handover among at least one terminal transmitting the measurement report message; / RTI > In the terminal, A transmission / reception unit for performing communication with a base station; And Receiving a measurement parameter from the base station for determining whether the terminal is located in the handover-enabled area, determining whether the terminal is located in the handover-enabled area using the received measurement parameter, Generating a measurement report message, transmitting the measurement report message to the base station, and transmitting the measurement report message to the base station based on a filtering result of filtering a terminal having a possibility of reverse handover among at least one terminal transmitting the measurement report message A control unit for controlling the handover to the selected target cell; .

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