KR20190063420A - Method and Apparatus for performing handover in a mobile communication system - Google Patents

Abstract

The present embodiments relate to a method of a terminal for performing handover in a mobile communication system and an apparatus thereof. According to an embodiment of the present invention, a method of a terminal for performing handover in a mobile communication system comprises the following steps: determining whether entered to a handover area; and performing soft handover on a control signal and performing hard handover on a data signal when entered to the handover area as a result of the determination.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a handover method in a mobile communication system,

The present invention relates to a method and an apparatus for performing a handover in a mobile communication system. More particularly, the present invention provides a method and apparatus for separating a control signal and a data signal from each other when a mobile station enters a handover region, and performing handover in a different manner for each of the segments.

In the case of LTE, which is generally used in mobile communication systems, hard handover is used in handover. Hard handover refers to a handover in which, when a terminal enters a handover region, the currently connected channel is released and then another channel is directly connected. In this case, if the terminal moves and an erroneous handover occurs, the service to be provided to the terminal may be interrupted, and the call may be disconnected due to the handover failure.

On the other hand, in CDMA, unlike LTE, soft handover is used for handover. Soft handover refers to a handover in which, when a terminal enters a handover region, it is connected to two channels from different base stations at the same time and then one channel is disconnected. In this case, stability of the handover can be ensured. However, since the UE must simultaneously receive signals on two channels, the complexity increases in controlling the handover. If two base stations connected to the UE transmit the same information There is a problem in that resources of the forward channel are wasted.

Therefore, when a mobile station performs handover in a mobile communication system, there is a need to introduce a handover method and apparatus that does not significantly increase overhead and complexity during handover, while improving stability of handover.

It is an object of the present invention to provide a handover method and apparatus for minimizing an increase in overhead and complexity at the time of handover while improving handover stability when a terminal performs handover in a mobile communication system.

According to an embodiment of the present invention, there is provided a method of performing a handover in a mobile communication system, the method comprising: determining whether or not the mobile terminal enters a handover region; And performing a soft handover for the control signal and a hard handover for the data signal.

According to another aspect of the present invention, there is provided a mobile station for performing a handover in a mobile communication system, the mobile station including a receiver for receiving a control signal or a data signal, a determination unit for determining whether or not the mobile station enters a handover region, And a controller for performing soft handover for the control signal when the mobile station enters the mobile station and performing hard handover for the data signal.

It is possible to provide a handover method and an apparatus that improve the stability of handover and do not significantly increase the overhead and complexity at the time of handover when the UE performs handover in the mobile communication system. It is possible to reduce arc cutting and delay in over time.

1 is a diagram illustrating a hard handover in a conventional LTE system.
2 is a diagram illustrating soft handover in a conventional CDMA system.
3 is a diagram illustrating a handover process according to the present embodiment.
4 is a diagram illustrating a structure of a terminal according to the present embodiment.
5 is a flowchart illustrating a handover procedure of a UE according to the present embodiment.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. In the drawings, like reference numerals are used to denote like elements throughout the drawings, even if they are shown on different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

In describing the components of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are intended to distinguish the components from other components, and the terms do not limit the nature, order, order, or number of the components. When a component is described as being "connected", "coupled", or "connected" to another component, the component may be directly connected or connected to the other component, Quot; intervening "or that each component may be" connected, "" coupled, "or " connected" through other components.

Herein, the MTC terminal may mean a terminal supporting low cost (or low complexity) or a terminal supporting coverage enhancement. In this specification, the MTC terminal may mean a terminal supporting low cost (or low complexity) and coverage enhancement. Alternatively, the MTC terminal may refer to a terminal defined in a specific category for supporting low cost (or low complexity) and / or coverage enhancement.

In other words, the MTC terminal in this specification may mean a newly defined 3GPP Release-13 low cost (or low complexity) UE category / type for performing LTE-based MTC-related operations. Alternatively, the MTC terminal may support enhanced coverage over the existing LTE coverage or a UE category / type defined in the existing 3GPP Release-12 or lower that supports low power consumption, or a newly defined Release-13 low cost low complexity UE category / type.

The wireless communication system in the present invention is widely deployed to provide various communication services such as voice, packet data and the like. A wireless communication system includes a user equipment (UE) and a base station (BS, or eNB). The user terminal in this specification is a comprehensive concept of a terminal in wireless communication. It is a comprehensive concept which means a mobile station (MS), a user terminal (UT), an SS (User Equipment) (Subscriber Station), a wireless device, and the like.

A base station or a cell generally refers to a station that communicates with a user terminal and includes a Node-B, an evolved Node-B (eNB), a sector, a Site, a BTS A base transceiver system, an access point, a relay node, a remote radio head (RRH), a radio unit (RU), and a small cell.

That is, the base station or the cell in this specification is interpreted as a comprehensive meaning indicating a partial region or function covered by BSC (Base Station Controller) in CDMA, NodeB in WCDMA, eNB in LTE or sector (site) And covers various coverage areas such as megacell, macrocell, microcell, picocell, femtocell and relay node, RRH, RU, and small cell communication range.

Since the various cells listed above exist in the base station controlling each cell, the base station can be interpreted into two meanings. i) the device itself providing a megacell, macrocell, microcell, picocell, femtocell, small cell in relation to the wireless region, or ii) indicating the wireless region itself. i indicate to the base station all devices that are controlled by the same entity or that interact to configure the wireless region as a collaboration. An eNB, an RRH, an antenna, an RU, an LPN, a point, a transmission / reception point, a transmission point, a reception point, and the like are exemplary embodiments of a base station according to a configuration method of a radio area. ii) may indicate to the base station the wireless region itself that is to receive or transmit signals from the perspective of the user terminal or from a neighboring base station.

Therefore, a base station is collectively referred to as a base station, collectively referred to as a megacell, macrocell, microcell, picocell, femtocell, small cell, RRH, antenna, RU, low power node do.

Herein, the user terminal and the base station are used in a broad sense as the two transmitting and receiving subjects used to implement the technical or technical idea described in this specification, and are not limited by a specific term or word. The user terminal and the base station are used in a broad sense as two (uplink or downlink) transmitting and receiving subjects used to implement the technology or technical idea described in the present invention, and are not limited by a specific term or word. Here, an uplink (UL, or uplink) means a method of transmitting / receiving data to / from a base station by a user terminal, and a downlink (DL or downlink) .

There are no restrictions on multiple access schemes applied to wireless communication systems. Various multiple access schemes such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), OFDM-FDMA, OFDM- Can be used. An embodiment of the present invention can be applied to asynchronous wireless communication that evolves into LTE and LTE-advanced via GSM, WCDMA, and HSPA, and synchronous wireless communication that evolves into CDMA, CDMA-2000, and UMB. The present invention should not be construed as limited to or limited to a specific wireless communication field and should be construed as including all technical fields to which the idea of the present invention can be applied.

A TDD (Time Division Duplex) scheme in which uplink and downlink transmissions are transmitted using different time periods, or an FDD (Frequency Division Duplex) scheme in which they are transmitted using different frequencies can be used.

In systems such as LTE and LTE-advanced, a standard is constructed by configuring uplink and downlink based on a single carrier or carrier pair. The uplink and the downlink are divided into a Physical Downlink Control Channel (PDCCH), a Physical Control Format Indicator CHannel (PCFICH), a Physical Hybrid ARQ Indicator CHannel, a Physical Uplink Control CHannel (PUCCH), an Enhanced Physical Downlink Control Channel (EPDCCH) Transmits control information through the same control channel, and is configured with data channels such as PDSCH (Physical Downlink Shared CHannel) and PUSCH (Physical Uplink Shared CHannel), and transmits data.

On the other hand, control information can also be transmitted using EPDCCH (enhanced PDCCH or extended PDCCH).

In this specification, a cell refers to a component carrier having a coverage of a signal transmitted from a transmission point or a transmission point or transmission / reception point of a signal transmitted from a transmission / reception point, and a transmission / reception point itself .

The wireless communication system to which the embodiments are applied may be a coordinated multi-point transmission / reception system (CoMP system) or a coordinated multi-point transmission / reception system in which two or more transmission / reception points cooperatively transmit signals. antenna transmission system, or a cooperative multi-cell communication system. A CoMP system may include at least two multipoint transmit and receive points and terminals.

The multi-point transmission / reception point includes a base station or a macro cell (hereinafter referred to as 'eNB'), and at least one mobile station having a high transmission power or a low transmission power in a macro cell area, Lt; / RTI >

Hereinafter, a downlink refers to a communication or communication path from a multipoint transmission / reception point to a terminal, and an uplink refers to a communication or communication path from a terminal to a multiple transmission / reception point. In the downlink, a transmitter may be a part of a multipoint transmission / reception point, and a receiver may be a part of a terminal. In the uplink, the transmitter may be a part of the terminal, and the receiver may be a part of multiple transmission / reception points.

Hereinafter, a situation in which a signal is transmitted / received through a channel such as PUCCH, PUSCH, PDCCH, EPDCCH, and PDSCH is expressed as 'PUCCH, PUSCH, PDCCH, EPDCCH and PDSCH are transmitted and received'.

In the following description, an indication that a PDCCH is transmitted or received or a signal is transmitted or received via a PDCCH may be used to mean transmitting or receiving an EPDCCH or transmitting or receiving a signal through an EPDCCH.

That is, the physical downlink control channel described below may mean a PDCCH, an EPDCCH, or a PDCCH and an EPDCCH.

Also, for convenience of description, the PDCCH, which is an embodiment of the present invention, may be applied to the PDCCH, and the PDCCH may be applied to the portion described with the EPDCCH.

Meanwhile, the High Layer Signaling described below includes RRC signaling for transmitting RRC information including RRC parameters.

The eNB performs downlink transmission to the UEs. The eNB includes a physical downlink shared channel (PDSCH) as a main physical channel for unicast transmission, downlink control information such as scheduling required for reception of a PDSCH, A physical downlink control channel (PDCCH) for transmitting scheduling grant information for transmission in a Physical Uplink Shared Channel (PUSCH). Hereinafter, the transmission / reception of a signal through each channel will be described in a form in which the corresponding channel is transmitted / received.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. The following terms are defined in consideration of the functions of the present invention, and these may be changed according to the intention of the user, the operator, or the like. Therefore, the definition should be based on the contents throughout this specification.

1 is a diagram illustrating hard handover in an LTE system.

Referring to FIG. 1, in an LTE system, a terminal 103 may exist in a boundary area between a first base station 101 and a second base station 102. 1 (a) shows a case where the terminal 103 exists in the service area of the first base station 101. In FIG. In this case, the first base station 101 may transmit the control signal and the data signal through the forward channel of the terminal.

In this case, the control signal may be a signal for transmitting control information such as PDCCH of the LTE system. The data signal may also refer to a signal that transmits user data, such as a PDSCH. The control signal and the data signal transmitted through the forward channel may be referred to as a forward signal or a downlink signal.

When the terminal 103 moves from the service area of the first base station 101 to the service area of the second base station 102, the handover is performed. At this time, in the LTE system, the connection with the first base station 101 is disconnected and the control signal and the data signal are received from the second base station 102 before connection with the second base station 102. That is, hard handover occurs.

2 is a diagram illustrating soft handover in a CDMA system.

2, a soft handover area in which a terminal 203 can simultaneously receive control signals and data signals from the first base station 201 and the second base station 202 can be established.

If the terminal 203 exists in the soft handover region, the terminal 203 can simultaneously receive the control signal and the data signal from the first base station 201 and the second base station 202. At this time, the contents of the control signal and the data signal transmitted from the first base station 201 and the second base station 202 to the terminal 203 are the same. Accordingly, the terminal 203 can obtain a diversity gain that can increase the reliability of the received signal by using the contents of the signal received from the first base station 201 and the second base station 202. [

The present embodiment proposes an efficient method for improving the performance of the handover. An object of the present invention is to provide a method for improving handover performance while minimizing an increase in complexity of a terminal as described above.

According to the present embodiment, if the terminal is within the service area of one base station, both the control signal and the data signal can be received from the base station. Hereinafter, when a handover occurs, a base station that is connected to a terminal and provides a service may be referred to as a source base station.

However, when the mobile station moves to reach the handover region, the mobile station can set a different base station to receive the signal according to the signal type for stability of service. That is, the terminal receives a control signal from a plurality of neighbor base stations, but can receive only a data signal from only one base station.

More specifically, a UE can receive a control signal from a plurality of base stations when entering a handover area, while a data signal can be received only by one base station. In this state, the UE can perform a process of changing a base station transmitting a data signal from a conventional base station to a new base station.

In addition, when a mobile station moves to a service area of a new base station, a process of changing a base station that transmits a data signal while receiving a control signal from a plurality of base stations can be performed.

Here, a base station that is conventionally connected, i.e., a base station that is connected to a terminal and provides a service when handover occurs, may be referred to as a source base station. When a new base station, i.e., a handover occurs, a base station to be connected to a new terminal to provide a service can be referred to as a target base station.

As described above, in order to perform the handover, the UE may first determine whether or not it enters the handover area.

For example, the UE can determine that it has entered the handover area when it can receive services from a plurality of base stations, that is, when there are two or more base stations corresponding to a channel state in which a service can be provided.

In another example, a terminal can receive services from a plurality of base stations, and can determine that a base station having the best channel state is a handover area when the base station is different from the currently connected base station.

3 is a diagram illustrating a handover process according to the present embodiment.

3 illustrates a process in which the MS 303 moves from the service area of the first BS 301 to the service area of the second BS 302. FIG.

3 (a) shows a state before handover occurs. The terminal 303 exists in the service area of the first base station 301, and both the control signal and the data signal are transmitted from the first base station 301 .

If the MS 303 moves from the service area of the first BS 301 to the service area of the second BS 302 and a handover occurs, (b) and (c). When the handover occurs, step (b) of FIG. 3 is performed first, and step (c) of FIG. 3 is performed.

Referring to FIGS. 3B and 3C, the terminal 303 can simultaneously receive control signals from the first base station 301 and the second base station 302, while the data signals are transmitted to the first base station 301 301) and the second base station (302).

The terminal 303 receives the data signal from the first base station 301 and the terminal 303 receives the data signal from the second base station 302 in FIG. Lt; / RTI > When the terminal 303 moves to the service area of the second base station 302 through the handover area, both of the control signal and the data signal are moved to a state of receiving the control signal and the data signal from the second base station 302 do.

In the handover process of FIG. 3, there is a step in which a terminal simultaneously receives a control signal from a plurality of base stations, but only one base station receives a data signal. Therefore, soft handover is performed on the control signal, and hard handover is performed on the data signal.

In this case, the control signal in this embodiment may be PDCCH, which is a control channel for performing forward / reverse link resource allocation as in LTE. Also, the data signal may be a channel including a message that the base station actually wants to transmit, such as a PDSCH of LTE.

In addition, at the time of handover, the base station transmitting the data signal in (b) and (c) of FIG. 3 can be fixed by a predetermined protocol. That is, in this case, the base station in which the base station and the terminal transmit the data signal according to a predetermined protocol can be fixed until a predetermined threshold time or the next handover state transition.

For example, the terminal may set the data signal to always be received only from the existing first base station before the handover is completed.

As another example, after entering the handover area, the mobile station can receive a data signal only from the first base station until a predetermined time (ex. 20 ms), and then receive the data signal only from the second base station.

On the other hand, FIGS. 3 (b) and 3 (c) show one state, and a method of changing a base station to receive a data signal according to a control signal transmitted momentarily may be used. That is, all of the control signals transmitted by the two base stations are received by the terminal, and the data signals are received only by the base station that has received the corresponding forward resource allocation.

At this time, the base station transmitting the data signal may be changed every TTI (Transmission Time Interval). That is, the terminal transmits channel state information (CSI) of the first base station and channel state information of the second base station over the reverse channel, and the base station to transmit the data signal to the terminal can be selected in consideration of the channel state information.

For example, the UE receives the data signal from the first base station because the channel state information of the first base station is good in the current TTI, and in the next TTI, the channel state information of the second base station is better and receives the data signal from the second base station .

When using this method, unlike the soft handover used in the existing CDMA, only one base station can set the control signal and the data signal to be transmitted to the terminal in the specific TTI. That is, in a specific TTI, a control signal and a data signal are transmitted only in one of the first base station and the second base station.

The terminal attempts to receive all the control signals transmitted from the first base station and the second base station. If the first base station sends a control signal, the first base station receives the transmitted data signal, whereas if the second base station sends a control signal, the second base station receives the transmitted data signal. In this case as well, the base station transmitting the signal may be different every TTI as described above.

As described above, there is a problem in that the complexity of receiving (demodulating and decoding) a control signal increases if the UE must receive all the control signals transmitted from two or more base stations every TTI. Therefore, the present embodiment proposes a method of reducing the complexity of the control signal receiving process.

For example, in the LTE system, a PDCCH for a UE can be transmitted through one of several candidate positions. Since the UE can not know to which position the PDCCH is to be transmitted, the UE can detect a PDCCH for itself by performing a blind search on various possible candidate positions.

For example, in the LTE system, the UE can perform blind search of up to 44 times on the PDCCH. If the existing method is used at the same time during handover, there is a problem that the complexity of PDCCH reception process of the UE increases.

Accordingly, the present embodiment proposes a method of reducing the reception complexity for the PDCCH of the UE in the handover region. The proposed method reduces the number of blind search cases when the number of base stations to receive control signals increases in the handover area.

For example, when the terminal communicates only with one base station, the blind search is performed 44 times. However, when the control signal is received from two or more base stations in the handover region, the blind search is performed with a reduced number of times than 44 .

Table 1 is a table summarizing the complexity reduction method of the blind search in the handover area proposed in this embodiment.

When receiving a control signal from one base station, the CCE aggregation level

When receiving control signals from two or more BSs, the CCE aggregation level
UE-specific Search Space

1,2,4,8
4.8
Common Search Space

4.8
4.8

In the LTE system, there are two search intervals: a UE-specific search space and a common search space. The aggregation levels of available control channel elements (CCEs) are determined for each search interval. In the UE-specific search interval, values of 1, 2, 4, and 8 can be used as the CCE aggregation level In the case of the common search interval, values of 4 and 8 can be used as the CCE aggregation level. The present embodiment is characterized in that the number of cases of blind search for control signals in such a handover area is reduced and used.

That is, in the handover area, the CCE aggregation level is limited to 4 and 8 in both the UE-specific search interval and the common search interval. The reason for limiting the value to such a high number is that the reception performance of the control signal is not good when the CCE aggregation level is 1 or 2 in the handover region. Thus, the complexity in the blind search process of the terminal can be reduced by limiting the available CCE aggregation level according to the location and channel state of the terminal.

4 is a diagram illustrating a structure of a terminal according to the present embodiment.

The terminal may include an antenna 400, a receiver 410, a receive frequency oscillator 420, a controller 430, a determiner 440, a transmitter 450, and a transmit frequency oscillator 460.

The antenna 400 plays a role of receiving a signal transmitted through a wireless channel and transmitting a signal transmitted by a remote node.

The receiving unit 410 reconstructs data based on the signal received from the antenna 400.

The receiving unit 410 may include an RF receiving block, a demodulation block, a channel decoding block, and the like. And the RF receive block may comprise a filter and an RF preprocessor. The channel decoding block may be configured to include a demodulator, a deinterleaver, and a channel decoder. The receiving unit 410 may perform a receiving process including demodulation / decoding of the control signal and the data signal.

The reception frequency oscillation unit 420 may generate a frequency for receiving the signal at the reception unit 410. Generally, the reception frequency and the transmission frequency are set differently in the FDD mode.

The determination unit 430 may determine whether the terminal enters the handover area based on the signal received by the reception unit 410. [

For example, the UE can determine that it has entered the handover area when it can receive services from a plurality of base stations, that is, when there are two or more base stations corresponding to a channel state in which a service can be provided.

In another example, a terminal can receive services from a plurality of base stations, and can determine that a base station having the best channel state is a handover area when the base station is different from the currently connected base station.

The control unit 440 controls the overall operation of performing the handover between the receiving unit 410 and the transmitting unit 450. In particular, it changes the operation of the receiving unit 410 according to whether or not a handover area is present, and adjusts the reception process for the data signal according to the resource allocation command transmitted to the control signal. Also, the control unit 440 can control the interface with the user through various input / output devices such as a display, a speaker, and a keyboard. In addition, the controller 440 controls the receiver 410 according to the channel state and the state of the terminal, analyzes the message transmitted by the base station, stores the analyzed message, and controls the terminal based on the stored contents . In addition, the controller 440 controls the transmitter 450 to transmit the reverse channel.

3, the control unit 440 performs a soft handover for the control signal and a hard handover for the data signal when the terminal enters the handover region as a result of the determination by the determination unit 430 as described above with reference to FIG. As shown in Fig.

The transmitter 450 generates a signal to be transmitted to the base station through the reverse channel under the control of the controller 440. That is, the transmitter 450 converts the signal to be transmitted to the base station through the reverse channel in the controller 440 into a form that can be transmitted through the radio resource, and provides the converted signal to the antenna 400.

The transmitting unit 450 may include a signal generating block, a channel coding block, a modulation block, an RF transmission block, and the like. The channel code block is composed of a modulator, an interleaver and a channel encoder. The RF transmission block consists of a filter and an RF preprocessor.

The transmission frequency oscillation unit 460 oscillates at a transmission frequency required for the transmission unit 450 to transmit a signal under the control of the control unit 440.

5 is a flowchart illustrating a handover procedure of a UE according to the present embodiment.

Hereinafter, an example in which handover is performed by the terminal 303 illustrated in FIG. 3 will be described.

First, the terminal 303 may determine whether it enters a handover area where handover should be performed (S500).

If the terminal 303 does not enter the handover area (S510-N), that is, if the terminal 303 is located only within the service area of one base station, the source base station providing the service to the current terminal, And receives the continuous control signal and the data signal from the first base station 301 (S560).

If it is determined that the MS 303 enters the handover region, the MS 303 performs soft handover for the control signal and hard handover for the data signal.

First, the terminal 303 may receive a control signal from the target base station to be newly connected after the handover, that is, the second base station 302 (S520). In this case, since the terminal 303 receives the control signals from the two base stations at the same time, soft handover is performed on the control signal.

In order to solve the control signal reception complexity problem that occurs when the terminal 303 receives control signals from the two base stations as described above with reference to FIG. 3, when performing a blind search on the control signal, The aggregation level of control channel elements (CCEs) used in a specific search space can be limited. At this time, the set level of the limited CCE may be 4 or 8.

The terminal 303 may then release receiving the data signal from the currently connected source base station (S530). Then, the terminal 303 can receive the data signal from the target base station (S540). Since the terminal first receives the data signal from the target base station after canceling the reception of the data signal from the source base station, performs hard handover on the data signal.

At this time, when hard handover is performed on the data signal as described above with reference to FIG. 3, the target base station to which the data signal is to be transmitted can be fixed until a preset threshold time or handover state transition.

3, when performing hard handover with respect to the data signal, the target base station to which the data signal is transmitted may be determined based on the channel state information on the received control signal. In this case, only one base station can receive the control signal and the data signal for each TTI.

Then, the terminal can cancel the control signal reception from the source base station and complete the handover (S550).

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. In addition, the embodiments disclosed in the present invention are not intended to limit the scope of the present invention but to limit the scope of the technical idea of the present invention. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

Claims (12)

A method for performing a handover in a mobile communication system,
Determining whether to enter a handover area; And
Performing a soft handover for the control signal when the mobile station enters the handover region and performing a hard handover for the data signal.
The method according to claim 1,
Wherein the base station to which the data signal is to be transmitted is fixed to a predetermined threshold time or a handover state transition when performing a hard handover with respect to the data signal.
The method according to claim 1,
Wherein the base station to which the data signal is to be transmitted is determined based on the channel state information on the received control signal when performing the hard handover with respect to the data signal.
The method of claim 3,
Wherein the control signal and the data signal are received only from one base station for each transmission time interval (TTI).
The method according to claim 1,
When the blind search is performed on the control signal, the aggregation level of the Control Channel Element used in the Common Search Space and the UE-specific Search Space is ≪ / RTI >
6. The method of claim 5,
Wherein the aggregation level is 4 or 8.
A terminal performing a handover in a mobile communication system,
A receiving unit for receiving a control signal or a data signal;
A determination unit for determining whether or not the mobile terminal enters a handover area; And
And performing a soft handover for the control signal when the mobile station enters the handover region and a hard handover for the data signal.
8. The method of claim 7,
Wherein the base station to which the data signal is to be transmitted is fixed up to a preset threshold time or a handover state transition when performing a hard handover with respect to the data signal.
8. The method of claim 7,
Wherein the base station to which the data signal is to be transmitted is determined on the basis of channel state information on the received control signal when hard handover is performed on the data signal.
10. The method of claim 9,
Wherein the control signal and the data signal are received only by one base station for each TTI (Transmission Time Interval).
8. The method of claim 7,
When the blind search is performed on the control signal, the aggregation level of the Control Channel Element used in the Common Search Space and the UE-specific Search Space is Wherein the terminal is defined by the terminal.
12. The method of claim 11,
Wherein the aggregation level is 4 or 8.

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