KR20140106368A - Methods and Apparatuses for Handover in Heterogeneous Networks - Google Patents

Abstract

The present invention relates to a method and an apparatus for a handover in heterogeneous networks, and more particularly, to a method and an apparatus for determining whether to perform a handover based on information about the speed of a terminal in a wireless communication network in which macro cells and small cells (or pico cells) overlap each other. A method of performing a handover in heterogeneous networks by a terminal includes the steps of: receiving configuration information from a base station, wherein the configuration information includes information necessary for measuring a moving state of the terminal or information necessary for measuring signal qualities of serving cells and neighboring cells; measuring the moving state and the signal quality of the terminal based on the configuration information; transmitting a measurement report, which includes the information about the moving state of the terminal, to the base station when the measurement result of the signal quality satisfies a measurement report condition; and performing handover when a high level signaling, including the information about a handover instruction, is received from the base station.′.

Description

[0001] The present invention relates to a method and apparatus for handover in heterogeneous networks,

The present invention relates to a handover method and apparatus for a terminal, and more particularly, to a handover method and apparatus for handover in a wireless communication network in which a macro cell and a small cell (small cell or pico cell) And to a method and apparatus for determining whether or not a signal is received.

As communications systems evolved, consumers, such as businesses and individuals, used a wide variety of wireless terminals. In a mobile communication system such as LTE (Long Term Evolution) and LTE-Advanced of the current 3GPP series, a high-speed and large-capacity communication system capable of transmitting and receiving various data such as video and wireless data outside a voice- It is required to develop a technique capable of transmitting large-capacity data in accordance with the above-described method.

It is possible to efficiently transmit data using a plurality of cells in a method for transmitting a large amount of data.

However, when data is transmitted using a plurality of cells as described above, cell boundaries are increased and frequent handover is performed.

In addition, since coverage of each of a plurality of cells is different, an overlapped portion of inter-cell coverage is reduced, and accordingly, a section in which a handover can be performed is reduced, resulting in a frequent handover failure.

In addition, when the terminal moves at high speed, unnecessary handover may occur.

According to the above-mentioned demand, the present invention proposes a method and apparatus for solving the problem caused by a handover failure and a frequent handover by using the mobile state information of the terminal in performing a handover procedure by the terminal do.

In addition, the present invention can prevent handover of a terminal when the terminal moves at high speed, and propose a method and apparatus for mitigating frequency interference of neighboring cells in this case.

According to an aspect of the present invention, there is provided a method for performing handover in a heterogeneous network, the method comprising: receiving information for measuring a movement state of a mobile station from a base station, information for measuring a signal quality of a serving cell and a neighboring cell, The method comprising the steps of: receiving configuration information including at least one of at least one of information on a mobile station and a mobile station; measuring the mobile state and signal quality of the mobile station based on the configuration information; Transmitting a measurement report to the base station and performing a handover when an upper layer signaling including handover command information is received from the base station.

According to another aspect of the present invention, there is provided a method for controlling handover of a terminal in a heterogeneous network, the method comprising: receiving a measurement report including information on the movement state of the terminal from the terminal; Determining whether to perform handover based on the frequency information of the base station, and transmitting the higher layer signaling including the handover command information to the terminal when the handover of the terminal is determined to be performed.

According to another aspect of the present invention, there is provided a mobile station comprising: a receiving unit for receiving configuration information including at least one of information for measuring a moving state of a mobile station from a base station and information for measuring a signal quality of a serving cell and a neighboring cell; And a transmitter for transmitting a measurement report including the movement status information of the terminal to the base station if the measurement result of the signal quality measurement condition satisfies the measurement report condition, The base station provides a terminal performing handover when an upper layer signaling including handover command information is received.

According to another aspect of the present invention, there is provided a handover control method for a mobile communication terminal, the handover control method comprising the steps of: determining whether a handover of a terminal is performed based on a reception unit for receiving a measurement report including mobile terminal status information, And a transmitter for transmitting the higher layer signaling including the handover command information to the terminal when the handover execution of the controller and the terminal is determined.

As described above, according to the present invention, the mobile station uses the mobile state information of the mobile station in performing the handover procedure, thereby preventing the occurrence of handover failure and frequent handover.

In addition, according to the present invention, when a mobile station moves at a high speed, the mobile station does not perform a handover. In this case, frequency interference of neighboring cells is mitigated, thereby achieving efficient communication.

1 is a diagram illustrating an example of a heterogeneous network scenario in a wireless communication system to which the present invention can be applied.
2 is a diagram illustrating an example of a conventional handover procedure.
3 is a diagram illustrating operations of a terminal and a base station according to an embodiment of the present invention.
4 is a diagram illustrating a method for determining whether or not a base station performs handover according to another embodiment of the present invention.
5 is a diagram illustrating operations of a Node B and a UE for mitigating frequency interference according to another embodiment of the present invention.
6 is a flowchart illustrating an operation of a terminal according to another embodiment of the present invention.
7 is a flowchart illustrating an operation of a base station according to another embodiment of the present invention.
8 is a block diagram illustrating a configuration of a terminal according to another embodiment of the present invention.
9 is a block diagram illustrating a configuration of a base station according to another embodiment of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference symbols as possible even if they are shown in 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.

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 the like.

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, and RU communication range.

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, the uplink and downlink are configured on the basis of one carrier or carrier pair to form a standard. The uplink and downlink transmit control information through a control channel such as a Physical Downlink Control Channel (PDCCH), a Physical Control Format Indicator CHannel (PCFICH), a Physical Hybrid ARQ Indicator CHannel (PHICH), a Physical Uplink Control CHannel And a data channel such as a Physical Downlink Shared CHannel (PDSCH), a Physical Uplink Shared CHannel (PUSCH), and the like.

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 multiplex transmission / reception point to a terminal, and an uplink refers to a communication or communication path from a terminal to a multiplex 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, and PDSCH is expressed as 'PUCCH, PUSCH, PDCCH and PDSCH are transmitted and received'.

The base station performs downlink transmission to the UEs. The BS includes a Physical Downlink Shared Channel (PDSCH), which is a primary physical channel for unicast transmission, and downlink control information such as scheduling required for PDSCH reception and an uplink data channel 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.

1 is a diagram illustrating an example of a heterogeneous network scenario in a wireless communication system to which the present invention can be applied.

In the LTE system, a heterogeneous network (HetNet) scenario in which a small cell having a smaller coverage than a macro cell is overlaid is constructed for data off loading in order to cope with a surge of data traffic have.

Figure 1 is a simplified representation of an example of a heterogeneous network scenario.

Referring to FIG. 1, the coverage of the small cell is included in the coverage of the macrocell, and the terminal 100 can enter the coverage of the small cell as it moves.

That is, the terminal 100 performs communication with the macro base station 110 within the coverage of the macrocell. As the terminal 100 moves 190, the terminal 100 enters the coverage of the small cell # 1 and can perform communication with the small cell base station 120.

Also, the terminal 100 may perform communication with the small cell base station 130 of the small cell # 2 by moving (191) from the small cell # 1 to the small cell # 2 coverage.

The terminal 100 may perform data offload in order to perform data communication by connecting to the small cell as the mobile terminal moves to the mobile terminal as described above.

As described above, the small cell exists in the coverage of the macro cell, and data off-loading is performed according to the movement of the terminal 100, thereby increasing the overall communication capacity of the wireless communication system. In addition, individual user communication speed and user experience can be improved.

Meanwhile, the small cell may use the same frequency (Intra frequency) as the macro cell, or may use another frequency (Inter frequency).

Hereinafter, a handover procedure of a conventional terminal will be briefly described in the situation of FIG.

2 is a diagram illustrating an example of a conventional handover procedure.

As the terminal 201 moves in the heterogeneous network, the terminal 201 can perform handover between a macro cell, a macro cell, a macro cell, a small cell, a small cell, or a small cell. Accordingly, the terminal 201 can continuously communicate with the base station and exchange data while moving.

Referring to FIG. 2, a base station (or a source base station) 202 is a base station that communicates with a current terminal 201, and a target base station 203 includes a target base station 203, . That is, the terminal 201 desires to perform a handover from the base station 202 to the target base station 203.

The base station (or source base station) 202 may be a macro cell base station or a small cell base station, and the target base station may be a macro cell base station or a small cell base station. The base station and the target base station may be either the macro cell base station or the small cell base station according to the handover between the macro cell, the macro cell, the macro cell, the small cell, the small cell, or the small cell. .

The handover procedure will be briefly described step by step with reference to FIG.

1. The base station 202 informs which measurement information the terminal 201 should report (S210).

For example, the base station 202 provides the UE with a measurement configuration through a RRC Connection Reconfiguration message. The measurement configuration may include at least one of the following information.

- Measurement Object: The terminal 201 may include information about an object to be measured. For example, the information may include frequency information, a physical cell ID for one or more cells to be measured, a black list cell ID, and an offset value for each cell.

- Reporting Configuration: may include information about conditions under which the terminal 201 makes a measurement report. It can be transmitted periodically or according to an event.

- Measurement ID: Identifies the measurement object and can include information indicating the relationship with the reporting configuration.

- Quantity Configuration: The terminal 201 may include information on a value to be measured. For example, reference signal received power (RSRP) and / or reference signal reception quality (RSRQ) information may be included.

- Measurement gap: It can include information about the period for measuring the signal quality for the frequency that is different from the frequency used for the present. No data is transmitted or received in this gap.

2. The UE 201 performs signal quality measurement on the Serving Cell and neighboring cells according to the received measurement configuration information (S212).

The UE 201 measures the signal quality of the serving cell and at least one neighboring cell based on the received measurement configuration information included in the RRC connection reconfiguration message.

The terminal 201 may transmit the measurement report including the measurement result to the base station 202 when the result of the measured signal quality satisfies the measurement report condition.

3. The terminal 201 determines whether the measurement report of the signal quality measurement result is triggered (S215).

The measurement report may be sent periodically to the base station 202 or if it satisfies the reporting conditions included in the measurement configuration information.

That is, the terminal 201 can determine whether a measurement report event is triggered. For example, there are A1, A2, A3, A4, A5, B1 and B2 events as a criterion by which the terminal 2010 makes a measurement report to the base station 202. Each event condition includes the above- The event may be transmitted to the UE 201 or may be preset in the UE 201. If an event related to the handover is an A3 event, the A3 event indicates that the received signal strength of the neighboring cell is' The A3 event enters the A3 event entering condition if the A3 event entry condition is greater than the A3 offset value.

If a time-to-trigger (TTT) value for determining the duration of the event entry condition is set to a too short time, unnecessary handover may occur, and a ping pong where repetitive handover occurs may occur. Problems can arise. On the other hand, if the TTT value is set to be too long, the connection with the source cell may be interrupted before the handover occurs.

4. When the measurement report event is triggered, the terminal 201 transmits a measurement report including the measured signal quality information to the base station 202 (S220).

For example, the measurement report may include the radio signal strength of the serving cell, the physical cell ID of the target base station 203, the radio signal strength (RSRP, RSRQ) of the target base station 203, and the like.

5. The base station 202 receives a measurement report from the terminal 201 and determines whether to hand over to the target base station 203 based on the information included in the measurement report (S225).

The base station 202 may determine the target base station 203 based on the information in the measurement report and the neighbor cell list information managed by the base station 202. [

6. When the handover is determined, the base station 202 transmits the AS security key value and the UE context information to be used by the target base station 203 and the target base station 203, and transmits a bearer path setting, A handover preparation procedure is performed (S230).

7. The base station 202 transmits handover command information to the UE 201 through a RRC connection reconfiguration message (S235).

The handover command information may include information such as a target C-RNTI value, a target radio bearer ID (DRB ID), and a target AS security key value to be used in the target base station 203.

8. The terminal 201 completes the handover according to the procedure of performing the handover procedure with the target base station 203 and can perform communication through the cell of the target base station 203 at step S240.

The terminal 201 and the base station 202 can perform handover according to the procedure described above. If the base station 202 does not determine handover of the terminal, steps 6 to 8 above are not performed.

The above-described handover process can be divided into three steps as follows.

Step 1: This is the stage before the A3 event entering condition occurs.

Step 2: A step before a terminal receives a handover command after an A3 event entering condition occurs.

Step 3: This is a step from when the UE receives the Handover command until the UE sends the Handover complete message.

In step 2, the UE determines whether the condition is maintained for a predetermined time (TTT) after the A3 event entry condition occurs, and transmits the measurement report.

Hereinafter, a TTT value for measurement report and a method for measuring the mobility state of the UE will be described in more detail.

A3 event entry condition (A3 event entering condition) TTT operated after occurrence can be scaled as follows to improve the handover performance according to the terminal's speed.

In addition, the MS can estimate the MS speed by performing mobility state detection every time the MS performs a handover.

For example, the UE measures the number of handovers performed in a predetermined time window and estimates a mobility state in three stages of Normal, Medium, and High according to the number of handovers. That is, the high level is the highest speed, the next is the medium level, and the lowest speed is normal.

The terminal scales the TTT value applied in the measurement report according to the speed of the terminal. For example, when the mobile station is in a high-level mobile state, the TTT value is multiplied by a specific scaling factor (e.g., sf-High) to change the TTT value. (sf-Medium) to change the TTT value.

As an example, the specific scaling factor (e.g., sf-High or sf-Medium) described above may have a value of one of 0.25, 0.5, 0.75,

 For example, a terminal with a default TTT of 100 ms, sf-Medium of 0.75, and sf-High of 0.5 is set to 100 ms in the normal mobility state and 100 ms * 0.75 in the mobility state. = 75 ms in the high mobility state, and 100 ms * 0.5 = 50 ms in the high mobility state as the TTT value.

This allows faster terminals to trigger and transmit measurement reports more quickly, thereby enabling faster handover.

The information for performing the above-described movement state detection can be delivered to the terminal through higher layer signaling (e.g., RRC connection reconfiguration message).

As described with reference to FIG. 1, in a heterogeneous network, cell boundaries are increased as compared to a network in which only existing macro cells exist, which means that handover must be performed more frequently as the mobile terminal moves.

In particular, the handover between a macro-small cell, a small cell, a small cell, or a small cell-macrocell is shorter than a handover between a macrocell and a macrocell when a coverage overlap period So handover failure (HOF) can occur frequently.

In addition, there is a problem that the probability of failure of a handover involving a small cell significantly increases for a terminal moving at a high speed.

In order to prevent the deterioration of the user experience due to the handover failure of the terminal in the heterogeneous network situation, the present invention includes movement information in the measurement report according to the A3 event triggering A method for transmitting the data is explained.

In addition, a method of determining whether a base station performs a handover based on speed information and measurement report information and performing a subsequent procedure according to the determination is described.

3 is a diagram illustrating operations of a terminal and a base station according to an embodiment of the present invention.

The UE 301 according to an embodiment of the present invention includes at least one of information for measuring the moving state of the UE 301 from the BS 302 and information for measuring and reporting the signal quality of the serving cell and neighboring cells , Measuring the movement state and signal quality of the terminal (301) based on the configuration information, and measuring the signal quality of the terminal (301) when the signal quality measurement result satisfies the measurement report condition, Transmitting a measurement report including information to the base station 302 and performing a handover when an upper layer signaling including the handover command information is received from the base station 302. [

Each step will be described in detail with reference to FIG.

The UE 301 according to an embodiment of the present invention includes at least one of information for measuring a moving state of the UE 301 and information for measuring and reporting a signal quality of a serving cell and a neighboring cell Information (S310).

The configuration information described above may include information for measuring and reporting the signal quality of the serving cell and the neighboring cell.

For example, the above-described information may include information necessary for measuring the quality of a signal of a serving cell and a neighboring cell that can be sensed by the UE 301, and reporting the measured quality to the BS 302.

For example, the measurement configuration information may be transmitted to the terminal 301 including the following parameters.

A detailed description of each parameter is as follows.

- Measurement objects: Parameters for the object to be measured by the terminal. The measurement objects set in the terminal are one of an intra-frequency measurement object, an inter-frequency measurement object, and an inter-RAT measurement object, respectively. For intra-frequency and inter-frequency measurements, the measurement object is one LTE carrier frequency.

- Reporting configuration: It is a parameter for setting information about when and how to report to the base station about the measurement result of the terminal. A case where a certain condition (event) is satisfied or a periodic report is defined as a reporting trigger condition is defined. The TTT (timeToTrigger) value used in the normal mobility state is also set here.

- Measurement identities: parameters related to identifiers (IDs) that link specific measurement objects with specific reporting settings.

- Quantity configurations: These are the settings for filtering the measurement quantity and measurement results.

- Measurement gaps: This is a parameter for the time allocated to the terminal so that it can be measured purely by the part where there is no transmission / reception of data of the terminal. Inter-frequency, inter-RAT measurements are performed during this period.

- s-Measure: It is a parameter for a value that determines whether to perform intra-frequency, inter-frequency, inter-RAT neighboring cell measurement according to the quality value of the serving cell. If the s-measure value is more than the value, the UE does not need to perform intra-frequency, inter-frequency, and inter-RAT neighboring cell measurements.

- speed status parameter (speedStatePars): consists of parameters that determine the mobility status of the terminal. A scaling factor for changing the mobility state change condition of the terminal and the TTT (timeToTrigger) value used for each mobility state are defined.

In addition, the above-described configuration information may include information necessary for measuring the movement state of the terminal 301. [

For example, the velocity state parameter, which is a parameter included in the measurement configuration information described above, may include information necessary for measuring the movement state.

As an example, the MobilityStateParameters information may be included in the measurement configuration information and transmitted. The information included in MobilityStateParameters will be briefly described below.

MobilityStateParameters information element

A detailed description of each parameter is as follows.

t-Evaluation: a parameter for the time required for the UE to detect a medium or high-speed moving state. That is, the number of handovers occurring during the t-Evaluation time is counted to detect a medium or high moving state.

t-HystNormal: This is a parameter for the time required for the terminal to detect a normal (normal) moving state. That is, when the medium or high moving state is not detected during the t-HystNormal time, it is switched to the normal (normal) moving state.

n-CellChangeMedium: This is a parameter for the number of handovers to be changed to a medium moving state. That is, when the number of handovers occurring during the t-Evaluation time exceeds the n-CellChangeMedium and the n-CellChangeHigh, the mobile station transitions to the middle movement state.

n-CellChangeHigh: This is a parameter for the number of handovers for changing to a high-speed moving state. That is, when the number of handovers occurring during the t-Evaluation time exceeds the n-CellChangeHigh, the UE switches to a high moving state.

The terminal 301 counts the number of times when handover occurs in the RRC connection state based on the received information. The moving state of the terminal can be determined according to how many times the handover has occurred during the set t-Evaluation time.

The configuration information including the measurement configuration information and the movement status parameter described above may be transmitted to the terminal 301 through higher layer signaling (e.g., RRC connection reconfiguration message) (S310). Also, measurement configuration information and movement state parameter related information, respectively, associated with signal quality measurement may be transmitted or transmitted together, respectively.

The terminal 301 receives the above-described configuration information from the base station 302 (S310), and measures the movement state and the signal quality based on the configuration information (S315).

For example, as described above, the signal quality of a serving cell and a neighboring cell is measured based on parameter information such as measurement object information and measurement cycle included in the measurement configuration information. In this case, measurements can be made on the signal strength (e.g., RSRP or RSRQ) and the results can be stored.

In addition, the terminal 301 can measure and determine the movement state of the terminal by counting the number of handovers of the terminal 301 based on the movement state parameter included in the received configuration information.

The terminal 301 according to the embodiment of the present invention transmits a measurement report including the movement state information of the terminal 301 to the base station 302 when the measurement result of the signal quality based on the above- (S325)

That is, when the A3 event triggering occurs, the terminal 301 transmits a measurement report to the base station 302 (S325).

The terminal 301 according to the embodiment of the present invention may be configured such that the measurement report event (for example, A3 event) condition is satisfied in accordance with the event trigger condition pre-set or the event trigger condition included in the movement state parameter of the configuration information described above And transmits a measurement report including the stored signal quality measurement result and information on the movement state of the terminal to the base station 302. [

More specifically, for example, the method of transmitting the movement state information to the base station 302 by the terminal 301 includes: 1) a method of including mobility state information of the terminal 301 in a measurement report message; And a method of including horizontal rate parameter information of a location information element in a measurement report message.

First Embodiment: A method of including mobility state information of the UE 301 in a measurement report message

The UE according to an exemplary embodiment of the present invention may include information on the movement status of the UE in the measurement report.

The movement state information according to an embodiment of the present invention may include at least one or more pieces of information among mobility state parameter information of the terminal set based on the movement state measurement result of the terminal and scaling factor information corresponding to the mobility state parameter of the terminal have.

Specifically, for example, the base station 302 transmits an A3 event (A3) to a specific physical cell identifier (PCI) using an RRC connection reconfiguration message in the case of connection / handover, And to configure mobility state information in the measurement report according to the triggering condition. Also, the mobile station status information for the A3 event may always be included in the terminal.

For example, a method of transmitting a measurement report including a mobility state parameter (speedStatePars) configured in advance in the terminal 301 in the above-described method may include a new parameter indicating information on mobility state or an information element information element) and can be included in the measurement report.

For example, a measurement report message may include measurement result parameters.

Below is an example of the measurement result parameters included in the measurement report.

MeasurementReport message

As can be seen, the measurement report message can include the measurement result parameter and the measurement result parameter can include the movement status information.

An example in which the above-mentioned mobility state parameter is included in the measurement result parameter is described below.

An example will be described in which the mobility state parameter information of the terminal is included in the information element of the measurement result parameter and the mobile state information of the terminal is transmitted to the base station.

MeasResult Information element

The measurement result parameter may be included as above when the mobility state parameter information is added as one information element, or may be included in the following manner in addition to the above-indicated method.

MeasResult Information element

The mobility parameter of the terminal, which is set according to the movement state of the terminal measured by the terminal 301, can be set to three levels of Normal, Medium, and High.

Therefore, the movement status information included in the measurement result parameter can be transmitted by adding the corresponding information element according to the mobility parameter information of Normal, Medium, and High set by the terminal.

Meanwhile, the method in which the above-described three-stage mobility state parameter is included in the measurement report is described as an example only, it may be included in another part of the measurement report message, and only the mobility parameter information May be included and transmitted.

That is, the measurement report according to an embodiment of the present invention may include the movement state information when the measurement result of the movement state of the terminal is equal to or greater than the reference state.

For example, only when the measurement result of the mobile station status is Medium or High, the information can be included in the measurement result parameter using the above method. If the measurement result of the mobile station status is Normal, it can be transmitted without including the corresponding information. In this case, the base station can recognize the mobile station status as normal when the corresponding information is not included.

The terminal 301 of the present invention may transmit scaling factor information corresponding to the mobility state parameter in the measurement report instead of the mobility state parameters (Normal, Medium, and High) described above.

For example, information on the scaling factor applied (e.g., sf-High / sf-Medium) may be included, depending on the mobility state instead of the MobilityState parameter.

The scaling factor may be information transmitted to the UE included in the measurement configuration message described above, or information preset in the UE.

The scaling factor is a value for correcting the TTT value of the UE according to the mobility state parameter set according to the movement state of the UE.

For example, a terminal with a default TTT of 100 ms, sf-Medium of 0.75, and sf-High of 0.5 is set to 100 ms in the normal mobility state and 100 ms * 0.75 in the mobility state. = 75 ms in the high mobility state, and 100 ms * 0.5 = 50 ms in the high mobility state.

As described with reference to FIG. 2, the scaling factor may be defined in the rate state parameter of the configuration information that the base station transmits to the terminal.

In addition, the terminal 301 can transmit the scaling factor information only in the case of a specific moving state as in the case of including the moving state parameter in the configuration information.

For example, in the case of the normal moving state, the UE can transmit without including the scaling factor information, and if the scaling factor information is not included, the BS can determine that the moving state of the UE is Normal.

In the above, a method of including the mobility state parameter of the terminal or the scaling factor information corresponding to the terminal in the method that the terminal 301 includes the movement state information of the terminal in the measurement report has been described.

Hereinafter, a method for transmitting a terminal including horizontal rate parameter information of a terminal based on location information will be described as another method.

Second Embodiment: A method of including a horizontal velocity parameter of a location information element

The movement state information according to another embodiment of the present invention may include horizontal velocity parameter information measured based on position information of the terminal.

That is, the measurement report is transmitted to the base station 302 including the horizontal speed parameter information so that the base station 302 can determine the moving state of the terminal.

The location information parameter of the terminal 301 includes information on the location information of the terminal based on measurement information of the Global Navigation Satellite System (GNSS) device and the terminal that can be included in the terminal 301.

For example, the information element for position information may be configured as follows.

LocationInfo information element

Among the information elements included in the position information parameter, the horizontal velocity information has bearing (0 ~ 359) and horizontal speed (0 ~ 2047) information.

That is, the measurement result parameter of the measurement report according to another embodiment of the present invention may include a position information parameter, and the included position information parameter may include the above-described horizontal velocity parameter.

For example, if the measurement report includes a location information parameter, the locationCoordinates element of the information element of the location information parameter is included, and gnss-TOD-mesc information may be included if necessary. Here, the measurement report according to another embodiment of the present invention may include a horizontal velocity element (if available, include the horizontal velocity).

The base station 302 can confirm the movement state information of the terminal 301 by checking the horizontal velocity parameter value included in the position information parameter of the measurement report.

In the above description, the method in which the terminal 301 transmits the measurement report to the base station 302 includes the movement status information. That is, at least one of the scaling factor (sf-Medium, sf-High) or the horizontal velocity parameter information corresponding to the mobility state parameter (Normal, Medium, High) Information may be included.

The base station 302 may receive the measurement report including the movement status information from the terminal 301 and determine whether the handover is performed considering the movement status information of the terminal 301 (S330).

If it is determined to perform handover, the base station 302 performs a preparation procedure for handover with the target base station 303 (S335).

The handover preparation procedure is a procedure for transmitting and receiving an AS security key value and a UE context information to be used by the target base station 303 and the target base station 303 as described in FIG. Can be performed.

When the preparation procedure is completed, the base station 302 transmits the upper layer signaling including the handover command information to the terminal 301 (S340).

The terminal 301 receives the handover command information and performs a handover procedure with the target base station 303 to perform communication through the target base station 303 (S345).

Hereinafter, a process of determining whether a handover of a mobile station is to be performed by receiving a measurement report including mobile status information from a mobile station according to another embodiment of the present invention will be described in detail.

4 is a diagram illustrating a method for determining whether or not a base station performs handover according to another embodiment of the present invention.

The base station according to another embodiment of the present invention includes a step of receiving a measurement report including information on the movement state of the mobile station from the mobile station and a step of determining whether handover of the mobile station based on the frequency information of the target base station included in the movement state information and measurement report And transmitting the higher layer signaling including the handover command information to the terminal when the handover execution of the terminal is determined.

Referring to FIG. 4, the BS receives a measurement report including movement state information from a terminal (S410). As described above, the movement state information may be a mobility state parameter of the terminal or a scaling factor corresponding to the mobility state parameter. Or the movement state information may be a horizontal velocity parameter value included in the position information parameter. Or at least one of the above-mentioned parameters may be combined information.

After receiving the measurement report, the base station determines whether the movement speed of the terminal based on the movement state information is equal to or greater than a reference value (S420).

The base station according to another embodiment of the present invention may determine to transmit the upper layer signaling including the handover command information when the moving speed of the mobile station is less than the reference value based on the moving state information at operation S425.

For example, the base station determines whether the movement speed of the terminal is faster than a preset threshold. If the mobile speed of the mobile station is less than the reference value, a handover process is performed according to the handover procedure (the handover preparation procedure and the handover command information terminal transmission procedure) with the target base station (S425).

The MS receiving the higher layer signaling (for example, the RRC connection reconfiguration message) including the handover command information can perform the handover procedure with the target base station based on the information included in the upper layer signaling.

According to another embodiment of the present invention, the base station may further include a step of determining whether the frequency of the target base station is the same as the frequency of the base station when the mobile speed of the mobile station is equal to or greater than a reference value, based on the movement status information S430).

The base station determines whether the frequency of the target base station is equal to the frequency of the base station based on the signal quality measurement result transmitted from the terminal in the measurement report without performing the handover procedure when the mobile speed of the terminal is equal to or greater than the reference value.

For example, if the mobile terminal is moving faster than the reference value, it is determined whether the target base station transmitted by the mobile station does not have the same frequency as the base station (intra frequency) or the other frequency band ).

The base station according to another embodiment of the present invention may further include transmitting control information for mitigating frequency interference to the target base station or the terminal when the frequency of the target base station is equal to the frequency of the base station in operation S440.

For example, handover is not performed when the mobile speed of the mobile station is equal to or greater than the reference value, so that frequency interference may occur in the mobile station if the frequency of the target base station is the same as the frequency of the base station.

Therefore, the base station can transmit the control information to the target base station or the terminal in order to mitigate the frequency interference.

The control information according to another embodiment of the present invention includes information for controlling the sub-frame of the target base station to be blanked or may include information for adjusting the radio link failure (RLF) timer value of the terminal have.

For example, if it is determined that the frequency of the target base station is equal to the frequency of the base station, the base station may send control information for controlling the small base station to configure the ABS (Almost Blank Sub-frame) .

In another example, the base station may transmit control information for controlling the terminal to configure a longer radio link failure timer value.

Alternatively, the above two control information may be sent at the same time.

The target base station of the small cell that has received the control information of the base station may not use the corresponding subframe or the terminal may set the RLF timer to be long to alleviate the frequency interference of the terminal.

If the frequency of the target base station is not equal to the frequency of the base station (S430), there is no interference problem even if the handover is not performed. Therefore, the mobile station can continue the communication without performing the handover without performing another operation.

The overall operation of the base station described above will be described again with reference to Fig.

5 is a diagram illustrating operations of a Node B and a UE for mitigating frequency interference according to another embodiment of the present invention.

Referring to FIG. 5, the base station 502 transmits configuration information including at least one of information for measuring the movement state of the terminal and information for signal quality measurement to the terminal 501 (S510).

In one example, the configuration information may be sent via higher layer signaling (e.g., an RRC connection reconfiguration message).

The terminal 501 transmits the measurement report including the movement status information to the base station 502 when the A3 event that measures the movement state and the signal quality based on the configuration information and transmits the measurement report to the base station 502 is triggered (S525).

As described above, the base station 502 determines whether the terminal is handed over by comparing the movement speed of the terminal with a preset reference value based on the terminal movement state information of the received measurement report (S530).

If the terminal movement speed is less than the reference value, it is determined that the terminal 501 should be handed over to the target base station 503, and the handover procedure of FIGS. 2 and 3 is performed.

If the terminal movement speed is equal to or greater than the reference value, it is determined that handover of the terminal 501 should not occur.

When the moving speed of the terminal 501 is equal to or higher than the reference value, the base station 502 transmits the communication service to the current terminal and the frequency of the target base station 503 based on the signal quality measurement result that can be received and included in the measurement report It is determined whether the frequencies of the base stations 502 are the same (S535).

If it is determined that the frequency bands are equal to each other, the base station 502 transmits control information for the ABS configuration to the target base station in order to mitigate frequency interference (S545). Alternatively, the base station 502 may transmit control information for adjusting the RLF timer value to the terminal 501 (S540). Alternatively, the base station may perform steps S540 and S545 in the same or sequential manner.

As described above, according to the present invention, in a heterogeneous network situation, when a terminal reports movement state information of a terminal in a measurement report, the base station determines whether handover is possible by using the mobile state information of the terminal, There is an effect of improving over performance.

The terminal can perform all of the operations of the terminal according to the contents described with reference to FIG. 2 to FIG.

6 is a flowchart illustrating an operation of a terminal according to another embodiment of the present invention.

A UE according to another embodiment of the present invention receives configuration information including at least one of information for measuring a movement state of a UE and information for measuring and reporting a signal quality of a serving cell and a neighboring cell from a base station (S610).

Then, the terminal measures the movement state and the signal quality of the terminal based on the configuration information (S620).

If the signal quality measurement result satisfies the measurement report condition, the terminal transmits a measurement report including the movement status information of the terminal to the base station (S630).

The movement state information according to another embodiment of the present invention may include at least one or more information among the mobility state parameter information of the terminal, the scaling factor information corresponding to the mobility state parameter of the terminal, and the horizontal velocity parameter information measured based on the position information of the terminal . ≪ / RTI >

As described above, when the mobile station transmits the mobility state parameter information or the scaling factor information, the mobile station may transmit the mobility state parameter information or the scaling factor information only when the mobile station is in a predetermined reference state or more.

When the MS receives the higher layer signaling including the handover command information from the BS, the MS performs handover (S640).

The base station can perform all the operations of the base station according to the contents described in FIGS.

7 is a flowchart illustrating an operation of a base station according to another embodiment of the present invention.

The base station according to another embodiment of the present invention includes receiving a measurement report including information on the movement state of the mobile station from the mobile station (S710).

As described above, the measurement report may include the movement state information of the terminal, and the movement state information may include information on the mobility state parameter of the terminal, the scaling factor information corresponding to the mobility state parameter of the terminal, And horizontal velocity parameter information.

The base station includes a step of determining whether the mobile station is handed over based on the movement state information and the frequency information of the target base station included in the measurement report (S720).

The base station compares the moving speed of the terminal with a preset reference value based on the moving state information. When the moving speed is less than the reference value, the handover of the terminal is determined. When the moving speed is the reference value or more, the terminal is determined not to perform the handover.

When the UE does not perform handover, the Node B may determine whether the frequency of the target Node B is the same as the frequency of the Node B and transmit the control information for mitigating the frequency interference to the target Node B or the UE.

If the base station determines handover, the base station may transmit the higher layer signaling including the handover command information to the mobile station in operation S730.

8 is a block diagram illustrating a configuration of a terminal according to another embodiment of the present invention.

8, a user terminal 800 according to another embodiment of the present invention includes a receiving unit 810, a control unit 820, and a transmitting unit 830.

The terminal 800 according to another embodiment of the present invention includes at least one of information for measuring a moving state of a terminal from a station and information for measuring and reporting a signal quality of a serving cell and a neighboring cell A control unit 820 for measuring a moving state of the mobile station and the signal quality based on the configuration information, and a control unit 820 for, if the signal quality measurement result satisfies the measurement report condition, And a transmitter 830 for transmitting the measurement report to the base station. The controller 820 may perform a handover if higher layer signaling including handover command information is received from the base station.

Specifically, the receiving unit 810 receives downlink control information, data, and a message from the base station through the corresponding channel. The configuration information may also include configuration information from the base station, and the configuration information may include information needed to set the mobile state of the terminal and information necessary to measure signal quality.

In addition, the controller 1120 measures the movement state information and the signal quality of the present invention and controls the overall operation of the terminal according to the transmission and measurement report.

For example, it is possible to set the mobile state of the UE, to measure the quality of the signal received from the serving cell and the neighbor cell, and to determine whether to trigger the measurement report event. In addition, when handover command information is received, a handover procedure with the target base station may be performed accordingly.

The transmission unit 1130 transmits downlink control information, data, and a message to the base station through the corresponding channel. Also, a measurement report including the movement status information is transmitted to the base station.

For example, the terminal may include at least one of the mobility state parameter information of the terminal, the scaling factor information corresponding to the mobility state parameter of the terminal, and the horizontal velocity parameter information measured based on the position information of the terminal, The above information can be transmitted.

In addition, all the operations of the terminal of the present invention described in FIGS. 2 to 7 can be performed.

9 is a block diagram illustrating a configuration of a base station according to another embodiment of the present invention.

9, a base station 900 according to another embodiment of the present invention includes a controller 910, a transmitter 920, and a receiver 930.

The base station 900 according to another embodiment of the present invention includes a receiver 930 that receives a measurement report including information on the movement state of a mobile station from a mobile station and a base station 900 that is based on the movement state information and frequency information of the target base station included in the measurement report And a transmitter 920 for transmitting the higher layer signaling including the handover command information to the terminal when the handover execution is determined.

Specifically, the receiver 930 can receive a measurement report including the above-described movement status information from the terminal, and can receive signals, messages, or data necessary for carrying out the present invention.

In addition, the controller 910 can determine whether the terminal is handed over based on the received configuration information. Specifically, based on the terminal movement state information, the movement speed of the terminal is compared with a preset reference value to determine whether to perform a handover.

If the movement speed of the mobile station is equal to or greater than a preset reference value, the mobile station determines not to perform handover of the mobile station, determines whether the frequency of the target base station is equal to the frequency of the base station, and determines transmission of control information for mitigating frequency interference have.

In addition, the control unit 910 can perform the determination and transmission / reception related control necessary for the base station to perform the present invention.

When the handover execution is determined, the transmitter 920 can transmit upper layer signaling including the handover command information and signals, messages, and data necessary for performing the present invention to the terminal.

If it is determined not to perform the handover of the terminal, the control information described in detail previously may be transmitted to the terminal or the target base station according to the same frequency.

The standard content or standard documents referred to in the above-mentioned embodiments constitute a part of this specification, for the sake of simplicity of description of the specification. Accordingly, it is to be construed that the content of the above standard contents and standard documents is added to or contained in the scope of the present invention.

According to the present invention described above, the use of the mobile state information of the mobile station in determining whether to perform handover of the mobile station enables the base station to prevent a handover failure and a frequent handover from occurring.

In addition, according to the present invention, when a terminal moves at a high speed, the terminal can be prevented from performing a handover. In this case, frequency interference of neighboring cells is mitigated, thereby achieving efficient communication.

In addition, according to the present invention, the terminal adds the movement state information of the terminal in the measurement report, thereby transmitting an effective handover procedure.

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. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas falling within the scope of the same shall be construed as falling within the scope of the present invention.

Claims (22)

A method for performing handover in a heterogeneous network,
Receiving configuration information including at least one of information for measuring a moving state of the mobile station from a base station and information for measuring and reporting a signal quality of a serving cell and a neighboring cell;
Measuring a moving state of the terminal and the signal quality based on the configuration information;
Transmitting a measurement report including the movement status information of the terminal to the base station if the measurement result of the signal quality satisfies the measurement report condition; And
And performing the handover if higher layer signaling including handover command information is received from the base station. The method according to claim 1,
The movement status information may include:
And information on at least one of mobility state parameter information of the terminal set based on the movement state measurement result and scaling factor information corresponding to the mobility state parameter of the terminal. 3. The method of claim 2,
The measurement report includes:
And the movement state information when the result of the movement state measurement of the terminal is equal to or greater than a reference state. The method according to claim 1,
The movement status information may include:
And the horizontal velocity parameter information is measured based on the position information of the terminal. A method for controlling handover of a terminal in a heterogeneous network,
Receiving a measurement report including the movement status information of the terminal from the terminal;
Determining whether the mobile station is handed over based on the movement status information and the frequency information of the target base station included in the measurement report; And
And transmitting an upper layer signaling including handover command information to the terminal when handover execution of the terminal is determined. 6. The method of claim 5,
The movement status information may include:
And information on at least one of mobility state parameter information of the terminal set based on the movement state measurement result and scaling factor information corresponding to the mobility state parameter of the terminal. 6. The method of claim 5,
The movement status information may include:
And the horizontal velocity parameter information is measured based on the position information of the terminal. 6. The method of claim 5,
The method of claim 1,
And to transmit an upper layer signaling including the handover command information when the moving speed of the terminal is less than a reference value based on the moving state information. 6. The method of claim 5,
The method of claim 1,
Further comprising the step of determining whether the frequency of the target base station is the same as the frequency of the base station when the moving speed of the mobile station is equal to or greater than a reference value based on the moving state information. 10. The method of claim 9,
The method of claim 1,
And transmitting control information for mitigating frequency interference to the target base station or the terminal if the frequency of the target base station is equal to the frequency of the base station. 11. The method of claim 10,
The control information includes:
Information for controlling the sub-frame of the target base station to be blank, or information for adjusting the radio link pager timer value of the terminal. A receiving unit for receiving configuration information including at least one of information for measuring a moving state of a mobile station from a base station and information for measuring and reporting a signal quality of a serving cell and a neighboring cell;
A controller for measuring a movement state of the terminal and the signal quality based on the configuration information; And
And a transmitter for transmitting a measurement report including the movement status information of the terminal to the base station if the measurement result of the signal quality satisfies the measurement report condition,
Wherein the controller performs handover when an upper layer signaling including handover command information is received from the base station. 13. The method of claim 12,
The movement status information may include:
The mobility state parameter information of the terminal set based on the movement state measurement result, and the scaling factor information corresponding to the mobility state parameter of the terminal. 14. The method of claim 13,
The measurement report includes:
And the movement state information when the result of the movement state measurement of the terminal is equal to or greater than a reference state. 13. The method of claim 12,
The movement status information may include:
And the horizontal velocity parameter information is measured based on position information of the terminal. A receiving unit for receiving a measurement report including information on the movement state of the terminal from the terminal;
A control unit for determining whether to perform handover of the UE based on the movement status information and the frequency information of the target base station included in the measurement report; And
And a transmitter for transmitting an upper layer signaling including handover command information to the terminal when handover execution of the terminal is determined. 17. The method of claim 16,
The movement status information may include:
The mobility state parameter information of the terminal set based on the movement state measurement result, and the scaling factor information corresponding to the mobility state parameter of the terminal. 17. The method of claim 16,
The movement status information may include:
And the horizontal velocity parameter information is measured based on position information of the terminal. 17. The method of claim 16,
Wherein,
And determines to transmit an upper layer signaling including the handover command information if the movement speed of the mobile station is less than a reference value based on the movement state information. 17. The method of claim 16,
Wherein,
Wherein the base station determines whether the frequency of the target base station is the same as the frequency of the base station when the movement speed of the mobile station is equal to or greater than a reference value based on the movement state information. 21. The method of claim 20,
The transmitter may further comprise:
Wherein the base station transmits control information for mitigating frequency interference to the target base station or the terminal when the frequency of the target base station is equal to the frequency of the base station. 22. The method of claim 21,
The control information includes:
Information for controlling the subframe of the target base station to be blank, or information for adjusting the radio link pager timer value of the terminal.

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