KR102293435B1 - Base station and terminal device, handover control method thereof - Google Patents

Abstract

The present invention proposes a technology that guarantees seamless mobility of a terminal without performance degradation in various scenarios required in a 5G communication system by realizing a handover method suitable for a 5G communication system that requires a beam forming environment (technology).

Description

BASE STATION AND TERMINAL DEVICE, HANDOVER CONTROL METHOD THEREOF

The present invention relates to an inter-cell handover technology of a terminal, and more particularly, a base station apparatus and a terminal apparatus realizing a handover method suitable for a communication system premised on a beamforming environment (technology), and handover of the apparatus It relates to a control method.

As the types of communication services and the transmission request speed in the LTE communication system diversify, LTE frequency extension and evolution to the 5G communication system are actively progressing.

5G communication system, while accommodating the maximum number of terminals based on limited radio resources, eMBB (enhanced mobile broadband) / mMTC (massive machine type communications) / uRLLC (ultra-reliable and It supports scenarios of low latency communications, high reliability and low latency communications).

And, in the 5G communication system, since an ultra-high frequency band with severe path attenuation is used, beam forming technology is essential.

Beam forming technology, on the premise that the number of antennas of the transmitter and the number of antennas of the receiver are provided, each of the transmitter and receiver forms an antenna beam focused (beam-formed) in a specific direction through its own antenna It is a technology for transmitting and receiving signals through this antenna beam.

On the other hand, in a communication system, a handover technique in which a terminal accesses and moves from a serving cell to a target cell is used due to the movement of the terminal.

The handover method in the current LTE communication system is based on the measurement information of the terminal measuring the signal of the serving cell and the signal of another cell (target cell) having a greater reception strength than the signal of the serving cell, under the control of the serving cell. This is a method in which the UE performs a handover procedure based on RRC signaling between the serving cell and the target cell to be handed over from the serving cell to the target cell.

That is, in the handover method in the LTE communication system, the target cell is selected only depending on the measurement information measured by the terminal, and the signaling for performing the handover procedure is RRC signaling based on the allocation resource between the terminal and the (serving or target) cell. is done through

In a 5G communication system that requires a beamforming environment (technology), if the existing handover method is used as it is in the 5G communication system, the performance deteriorates due to the difference in the actual wireless environment during handover due to relying only on the measurement information measured by the terminal. There is a possibility of occurrence, and since it is based on RRC signaling, there is a problem that there is a high possibility of service outage due to a sudden change in the wireless environment during handover.

That is, the existing handover method cannot be used as it is in the 5G communication system in which the beam forming environment (technology) is premised.

However, up to now, a separate handover method suitable for a 5G communication system has not been proposed as a remedy.

Accordingly, in the present invention, it is intended to propose a new handover method suitable for a 5G communication system.

The present invention was created in view of the above circumstances, and an object of the present invention is to realize a handover method suitable for a 5G communication system premised on a beam forming environment (technology).

A base station apparatus according to a first aspect of the present invention for achieving the above object includes: a terminal recognition unit for recognizing a terminal requiring handover from a serving cell to a target cell; a linkage unit for confirming a measurement result obtained by measuring an uplink signal of the terminal from at least one target candidate cell; and a target cell determiner configured to determine a target cell to be handed over by the terminal among the at least one target candidate cell based on the measurement result measured in the at least one target candidate cell.

Preferably, the interworking unit transmits an uplink signal measurement and handover preparation request of the terminal to a neighboring cell located within a predetermined distance from the serving cell, and measures and handover the preparation request among the neighboring cells A neighboring cell that returns a ready response of can be selected as a target candidate cell.

Preferably, when the at least one target candidate cell is selected, the linkage unit may instruct the terminal to transmit an uplink signal to be measured in the at least one target candidate cell.

Preferably, the target cell determiner, based on a measurement result of measuring an uplink signal of the terminal in the at least one target candidate cell, selects a target candidate cell having the best measurement result among the target candidate cells as the target cell can decide

Preferably, the target cell determiner, when the number of target candidate cells with the best measurement result among the target candidate cells is two or more, the radio resource usage rate being used among the two or more target candidate cells is lower or more from the serving cell A distant target candidate cell may be determined as the target cell.

Preferably, the target cell determiner may instruct the terminal to handover to the determined target cell, so that the terminal performs a handover procedure from the serving cell to the target cell according to the handover command. .

Preferably, the target cell is notified of the determination of the target cell for the terminal, so that the target cell can transmit the handover command to the terminal when transmission of the handover command fails.

A terminal device according to a second aspect of the present invention for achieving the above object includes: a reporting unit for reporting measurement information to the serving cell when handover is requested based on signal measurement from a serving cell; a transmitter for transmitting an uplink signal to be measured in at least one target candidate cell selected based on the location of the serving cell; and a handover performing unit configured to perform a handover procedure to a target cell determined from among the at least one target candidate cell based on a measurement result of measuring the uplink signal in the at least one target candidate cell.

In accordance with a third aspect of the present invention for achieving the above object, a handover control method of a base station apparatus includes: a terminal recognition step of recognizing a terminal requesting a handover from a serving cell to a target cell; a candidate cell interworking step of confirming a measurement result obtained by measuring an uplink signal of the terminal from at least one target candidate cell; and a target cell determining step of determining a target cell to be handed over by the terminal among the at least one target candidate cell based on the measurement result measured in the at least one target candidate cell.

Preferably, the candidate cell interworking step includes transmitting an uplink signal measurement and handover preparation request of the terminal to a neighboring cell located within a predetermined distance from the serving cell, and measuring the preparation request among the neighboring cells and a neighbor cell that returns a handover ready response response may be selected as a target candidate cell.

Preferably, when the at least one target candidate cell is selected, the method may further include instructing the terminal to transmit an uplink signal to be measured in the at least one target candidate cell.

Preferably, in the target cell determining step, based on a measurement result of measuring an uplink signal of the terminal in the at least one target candidate cell, a target candidate cell having the best measurement result among the target candidate cells is selected as the target determining a cell; and when two or more target candidate cells having the best measurement result among the target candidate cells, a target having a smaller radio resource usage rate among the two or more target candidate cells or a target having a greater distance from the serving cell The method may further include determining a candidate cell as the target cell.

Preferably, the method comprising: instructing the terminal to handover to the determined target cell, so that the terminal performs a handover procedure from the serving cell to the target cell according to the handover command; and notifying the target cell of the determination of the target cell for the terminal so that, when transmission of the handover command fails, the target cell can transmit the handover command to the terminal.

In a handover control method of a terminal device according to a fourth aspect of the present invention for achieving the above object, a reporting step of reporting measurement information to the serving cell when handover is requested based on signal measurement from a serving cell ; a transmitting step of transmitting an uplink signal to be measured in at least one target candidate cell selected based on the location of the serving cell; and a handover performing step of performing a handover procedure to a target cell determined from among the at least one target candidate cell based on a measurement result of measuring the uplink signal in the at least one target candidate cell. .

Accordingly, according to the base station device and the terminal device of the present invention, and the handover control method of the device, a handover method suitable for the 5G communication system premised on the beam forming environment (technology) is realized, thereby providing various requirements for the 5G communication system. It derives the effect of guaranteeing the seamless mobility of the terminal without degrading the performance of the scenario.

1 is an exemplary diagram showing the structure of a communication system to which the present invention is applied.
2 is a block diagram showing the configuration of a base station apparatus according to a preferred embodiment of the present invention.
3 is a block diagram showing the configuration of a terminal device according to a preferred embodiment of the present invention.
4 is an exemplary diagram showing a flowchart from a system point of view in which a handover control method (method) according to a preferred embodiment of the present invention is realized.
5 is a control flowchart illustrating a handover control method of a base station apparatus according to a preferred embodiment of the present invention.
6 is a control flowchart illustrating a handover control method of a terminal device according to a preferred embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

The present invention relates to a technology related to a communication system employing a beamforming technology.

More specifically, the present invention is to realize a handover method suitable for a communication system that is premised on a beam forming environment (technology).

As a communication system adopting beamforming technology, a 5G communication system introduced in the future may be considered.

As the types of communication services and the transmission request speed in the LTE communication system diversify, LTE frequency extension and evolution to the 5G communication system are actively progressing.

5G communication system, while accommodating the maximum number of terminals based on limited radio resources, eMBB (enhanced mobile broadband) / mMTC (massive machine type communications) / uRLLC (ultra-reliable and It supports scenarios of low latency communications, high reliability and low latency communications).

In the 5G communication system, since an ultra-high frequency band with severe path attenuation is used, beam forming technology is essential.

Beam forming technology, on the premise that the number of antennas of the transmitter and the number of antennas of the receiver are provided, each of the transmitter and receiver forms an antenna beam focused (beam-formed) in a specific direction through its own antenna It is a technology for transmitting and receiving signals through this antenna beam.

1 schematically shows the structure of a communication system to which the present invention is applied, for example, a 5G communication system.

As can be seen from FIG. 1, the base station and the terminal (transmitting/receiving device) adopt a beamforming technology, and the terminal can use a communication service through a signal (signaling, data, etc.) transmitted and received based on the beamforming technology with the base station. have.

In FIG. 1, it is assumed that each base station NB#1, #2, #3 forms a single cell Cell#1, #2, and #3.

On the other hand, in a communication system, a handover technique in which a terminal accesses and moves from a serving cell to a target cell is used due to the movement of the terminal.

The handover method in the current LTE communication system is based on the measurement information of the terminal measuring the signal of the serving cell and the signal of another cell (target cell) having a greater reception strength than the signal of the serving cell, under the control of the serving cell. This is a method in which the UE performs a handover procedure based on radio resource control (RRC) signaling between the serving cell and the target cell to perform handover from the serving cell to the target cell.

That is, in the handover method in the LTE communication system, the target cell is selected only depending on the measurement information measured by the terminal, and the signaling for performing the handover procedure is RRC signaling based on the allocation resource between the terminal and the (serving or target) cell. is done through

However, as shown in FIG. 1, if the existing handover method is adopted in the 5G communication system as it is in the 5G communication system premised on the beam forming environment (technology), the performance of various scenarios required by the 5G communication system is not degraded. There is a problem in that it is difficult to ensure seamless mobility of the terminal.

Specifically, since the existing handover method depends only on the measurement information measured by the terminal, when employed as it is in the 5G communication system due to the narrow beam-forming area (b) compared to the existing (a), the terminal in the cell ( There is a problem that may cause performance degradation due to a difference in a radio environment between a time point at which signals of the serving and target) are measured and a time point of a handover.

In addition, since the existing handover method is based on RRC signaling, when employed as it is in the 5G communication system due to the narrow beam-forming area (b) compared to the existing (a), the rapid wireless environment due to the movement of the terminal Due to the change, there is a problem that may cause service outage due to a cause such as release of an allocated resource between the terminal and the (serving or target) cell.

That is, in a 5G communication system that is premised on a beamforming environment (technology), it is not suitable for adopting the existing handover method as it is.

Accordingly, in the present invention, it is intended to propose a new handover method suitable for a 5G communication system.

Hereinafter, with reference to FIG. 2, a configuration of a base station apparatus according to a preferred embodiment of the present invention will be described.

As shown in FIG. 2 , the base station apparatus 100 according to the present invention includes a terminal recognition unit 110 for recognizing a terminal requiring handover from a serving cell to a target cell, and at least one target candidate cell. Based on the interworking unit 120 confirming the measurement result of measuring the uplink signal of the terminal, and the measurement result measured in the at least one target candidate cell, the terminal performs handover of the at least one target candidate cell and a target cell determining unit 130 that determines a target cell to be used.

The base station apparatus 100 of the present invention corresponds to each of the base stations NB#1, #2, and #3 shown in FIG. 1 , but for convenience of description, it is assumed that the base station NB#1. would.

And, in FIG. 1, it is assumed that each of the base stations NB#1, #2, and #3 forms a single cell Cell#1, #2, and #3. Therefore, the base station and the cell formed by the base station are It would be safe to see them as the same subject.

The terminal recognition unit 110 recognizes the terminal 10 requiring handover from the serving cell, that is, the cell (Cell#1) formed by the base station (NB#1) to the target cell.

Basically, the terminal 10 measures a signal from the serving cell (Cell #1) to which it is connected, and when the measured value (eg, RSRP (Reference Signal Received Power)) falls below a threshold, handover is required. It is determined that the measurement information is reported to the serving cell (Cell#1).

Accordingly, the terminal recognition unit 110 recognizes the terminal 10 reporting measurement information among terminals servicing the cell (Cell#1) as a terminal requiring handover from the cell (Cell#1) to the target cell. can do.

The interworking unit 120 checks a measurement result obtained by measuring an uplink signal of the terminal 10 from at least one target candidate cell when the terminal 10 requiring handover is recognized.

More specifically, the base station apparatus 100 may hold information on neighboring cells (neighboring base stations) located within a predetermined distance.

Alternatively, the base station apparatus 100 may obtain information about a neighboring cell (neighboring base station) from an external central apparatus, if necessary.

Accordingly, the linkage unit 120 may identify a neighboring cell (neighboring base station) located within a predetermined distance from the cell (Cell#1) based on the retained or acquired information.

Upon recognizing the terminal 10 requiring handover, the interworking unit 120 transmits the uplink signal measurement and handover preparation request of the terminal 10 to the previously checked neighbor cell (neighboring base station).

Hereinafter, it will be described that the neighboring cells identified in the base station apparatus 100 and NB#1 are a cell (Cell#2), a cell (Cell#3), and a cell (Cell#4).

In this case, when recognizing the terminal 10 requiring handover, the interworking unit 120 checks the uplink signal measurement and handover preparation request of the terminal 10 in the neighboring cells (Cells #2, #3, # 4) can be transmitted to each.

Each of the neighboring cells (Cell#2, #3, #4), according to the preparation request received from the base station apparatus 100, NB#1, the number of terminals accommodated in it, the amount of traffic, the radio resource usage rate in use, etc. Based on the determination of whether the terminal handover can be accepted or not, it is possible to return a measurement and handover preparation possible response to the base station apparatus 100 (NB#1) if possible.

Accordingly, the interworking unit 120 selects a neighbor cell that returns a measurement and handover preparation possible response to the preparation request among the neighboring cells that have transmitted the uplink signal measurement and handover preparation request of the terminal 10, as a target candidate. select cell.

In this way, the base station apparatus 100 (NB#1) of the present invention selects a candidate target cell that can become a target cell during handover of the current terminal 10 from among neighboring cells, and selects the selected candidate target cell. There is an effect of predicting/preparing a situation in which the terminal 10 may be handed over by allowing the terminal 10 to measure an uplink signal to be transmitted.

Hereinafter, it is assumed that cells (Cell#2, #3) are selected as candidate target cells among the neighboring cells (Cell#2, #3, #4) of the base station apparatus 100 and NB#1. .

When at least one target candidate cell (Cell#2, #3) is selected, the interworking unit 120 transmits an uplink signal to be measured in the target candidate cell (Cell#2, #3). command to

In this case, the terminal 10 will transmit an uplink signal, specifically, a reference signal (RS) for measurement in a candidate target cell according to a command from the base station apparatus 100 (NB#1).

In this way, the base station apparatus 100, NB#1 of the present invention has an effect of predicting/preparing that a target cell to be handed over is to be determined by allowing the terminal 10 to transmit an uplink signal RS. .

Accordingly, the interworking unit 120 receives the measurement result of measuring the uplink signal, that is, the RS of the terminal 10 from the target candidate cells (Cells #2 and #3), and receives the target candidate cells (Cells #2, #3). ), you can check the measurement results.

At this time, the base station apparatus 100 (NB#1), that is, the serving cell (Cell#1) may also receive and measure the uplink signal RS of the terminal 10 .

Accordingly, the base station apparatus 100 (NB#1), the measurement result measured in the serving cell (Cell#1), for example, the measurement value (eg, RSRP) is the measurement result measured in the target candidate cells (Cell#2, #3), that is, If it is superior to the measured value (eg, RSRP), it is preferable not to proceed with the handover procedure any longer because the handover of the terminal 10 is unnecessary.

Therefore, hereinafter, for convenience of explanation, a measurement result, for example, a measurement value (eg RSRP) measured in the serving cell (Cell#1) is a measurement result measured in the target candidate cells (Cell#2, #3), that is, a measurement value (eg : RSRP), we will exclude cases that are superior to that of RSRP.

The target cell determination unit 130, based on the measurement result measured in the target candidate cells (Cells #2, #3), the target of the target candidate cells (Cells #2, #3) to the terminal 10 to handover determine the cell.

Specifically, the target cell determination unit 130, the target candidate cell (Cell #2, #3) based on the measurement result of measuring the uplink signal (RS) of the terminal 10, for example, the measurement value (eg, RSRP) , a target candidate cell having the best measurement (eg, RSRP) among the target candidate cells (Cells #2 and #3) may be determined as the target cell.

This means that the measurement value (eg, RSRP) measured the uplink signal (RS) of the terminal 10 is the best, that the target candidate cell that measured the measurement value (eg RSRP) is the beam with the terminal 10 . This is because it means that the forming-based transmit/receive antenna beams are best mapped to each other.

Meanwhile, among the target candidate cells (Cells #2 and #3), the number of target candidate cells having the best measurement result, for example, a measurement value (eg, RSRP) may be not one but two or more.

In this case, the target cell determiner 130, among the two or more target candidate cells with the best measurement result, for example, a measurement value (eg, RSRP), the radio resource usage rate being used is smaller or more from the serving cell (Cell#1). A distant target candidate cell may be determined as the target cell.

This means that, when the target candidate cell with a lower radio resource usage rate in use becomes the target cell during handover of the current terminal 10 and accommodates the terminal 10, the terminal is higher than the target candidate cell having a larger radio resource usage rate in use. This is because there is a high possibility that the radio resources that can be allocated to (10) are sufficient.

In addition, the more distant the target candidate cell from the serving cell (Cell#1), the closer the measurement result, e.g., the measurement value (eg, RSRP), of the target candidate cell closer to the serving cell (Cell#1) is the same. This is because there is a high possibility that the terminal 10 is moving in the direction of the corresponding target candidate cell.

Hereinafter, for convenience of description, it is assumed that the cell (Cell#3) among the target candidate cells (Cell#2, #3) is determined as the target cell.

When the target cell (Cell#3) is determined, the target cell determination unit 130 instructs the terminal 10 to handover to the determined target cell (Cell#3), and the terminal 10 responds to the handover command. A handover procedure from the serving cell (Cell#1) to the target cell (Cell#3) is performed.

Accordingly, the terminal 10 transmits and receives a signal (signaling, message, etc.) according to the handover procedure according to the handover command, and performs a handover procedure from the serving cell (Cell#1) to the target cell (Cell#3). something to do.

Furthermore, when the target cell (Cell#3) is determined, the target cell determination unit 130 informs the target cell (Cell#3) of the determination of the target cell for the terminal 10, and the serving cell (Cell#1) ), that is, it is preferable to enable the target cell (Cell#3) to transmit the handover command to the terminal 10 when the transmission of the handover command transmitted to the terminal 10 by the base station apparatus 100 or NB#1 fails. .

In this case, a method of recognizing transmission failure of a handover command may be various according to definition.

For example, the target cell (Cell#3), i.e., the base station (NB#3), receives the target cell determination fact from the serving cell (Cell#1) of the terminal 10, i.e., the base station devices 100 and NB#1. Then, when a signal (signaling, message, etc.) related to the handover procedure is not received from the terminal 10 until a preset time elapses, the handover transmitted by the base station apparatus 100 and NB#1 to the terminal 10 It can be recognized as a command transmission failure.

As described above, the base station apparatus of the present invention uses the measurement information reported from the terminal only to recognize the handover request to the terminal, and transmits the uplink signal (RS) of the terminal at the base station (candidate target cell) end. A new handover technique in which a handover or a target cell is determined based on the measured measurement result, and a serving cell or a target cell transmits a handover command to the UE is realized.

As such, when the new handover method realized in the present invention is applied to a communication system (eg, 5G) premised on a beam forming environment (technology), unlike the existing handover method that depends only on measurement information measured by the terminal, Since the difference in the radio environment between the time when the terminal measures the signal of the serving cell (measurement information report time) and the handover time (the target cell determination time) is reflected, there is an effect of solving the problem of performance degradation.

In addition, when the new handover method realized in the present invention is applied to a communication system (eg, 5G) premised on a beam forming environment (technology), unlike the existing handover method based on RRC signaling, a rapid wireless environment Since it can be free from causes such as release of allocated resources between the terminal and (serving or target) cell due to change, there is an effect of solving the problem of service outage.

Hereinafter, the configuration of a terminal device according to a preferred embodiment of the present invention will be described with reference to FIG. 3 .

As shown in FIG. 3 , the terminal device 200 according to the present invention includes a reporting unit 210 that reports measurement information to the serving cell when a handover is requested based on signal measurement from a serving cell; , a transmitter 220 for transmitting an uplink signal to be measured in at least one target candidate cell selected based on the location of the serving cell, and a measurement by measuring the uplink signal in the at least one target candidate cell and a handover performing unit 230 for performing a handover procedure to a target cell determined from among the at least one target candidate cell based on the result.

The terminal device 200 of the present invention will be described on the assumption that it is the terminal 10 shown in FIG. 1 .

The reporting unit 210 reports measurement information to the serving cell (Cell#1) when a handover is requested based on signal measurement from the serving cell (Cell#1) to which the terminal device 200 is connected. .

For example, the reporting unit 210 measures a signal from a serving cell (Cell#1) to which the terminal device 200 is connected, and when the measured value (eg, RSRP) falls below a threshold value, handover is requested. It may be determined as a case and the measurement information may be reported to the serving cell (Cell#1).

The transmitter 220 transmits an uplink signal to be measured in at least one target candidate cell selected based on the location of the serving cell (Cell#1).

As described above, in the present invention, when the serving cell (Cell#1), that is, the base station apparatus 100, NB#1, receives measurement information from the terminal apparatuses 200 and 10, the current terminal apparatus 200, 10) during handover, a candidate target cell that can be a target cell is selected, and the selected candidate target cell measures an uplink signal to be transmitted from the terminal devices 200 and 10, 10) predicts / prepares for a situation in which handover can be performed.

Then, the base station apparatus 100 (NB#1) causes the terminal apparatuses 200 and 10 to transmit an uplink signal RS to predict/prepare that a target cell to be handed over is to be determined.

That is, when receiving an uplink signal transmission command for measurement in a target candidate cell from the base station apparatus 100 (NB#1), the transmitter 220 may transmit an uplink signal RS according to the command. .

In this case, the uplink signal RS transmitted by the terminal apparatuses 200 and 10 will be received and measured by the base station apparatus 100 and NB#1 and the target candidate cells Cells #2 and #3, respectively.

The handover performing unit 230, based on the measurement result of measuring the uplink signal RS in at least one target candidate cell, that is, the target candidate cell (Cell#2, #3), the target candidate cell (Cell#2) , #3), a handover procedure to the determined target cell is performed.

Specifically, as described above, the base station apparatus 100, NB#1, based on the measurement results measured in the target candidate cells (Cell#2, #3), the target candidate cells (Cell#2, #3) The terminal devices 200 and 10 determine a target cell to be handed over.

Hereinafter, for convenience of description, it is assumed that the cell (Cell#3) among the target candidate cells (Cell#2, #3) is determined as the target cell.

In this case, the base station apparatuses 100 and NB#1 instruct the terminal apparatuses 200 and 10 to handover to the determined target cell (Cell#3).

Accordingly, when a handover command from the base station apparatus 100 (NB#1) to the target cell (Cell#3) is received, the handover performing unit 230 receives a signal (signaling, message) according to the handover procedure according to the command. etc.) to perform a handover procedure from the serving cell (Cell#1) to the target cell (Cell#3).

Meanwhile, in the present invention, when the transmission of the handover command transmitted from the serving cell (Cell#1), that is, the base station device (100, NB#1) to the terminal device (200,10) fails, the handover in the target cell (Cell#3) It is defined so that an over command can be transmitted to the terminal devices 200 and 10 .

Accordingly, even when a handover command from the target cell (Cell#3) to the target cell (Cell#3) is received, the handover performing unit 230 receives a signal (signaling, message) according to the handover procedure according to the command. etc.) to perform a handover procedure from the serving cell (Cell#1) to the target cell (Cell#3).

As described above, the terminal device of the present invention uses the measurement information reported from the terminal only to recognize the handover request to the terminal, and transmits the uplink signal (RS) of the terminal from the base station (candidate target cell) end. A new handover technique in which a handover or a target cell is determined based on the measured measurement result, and a serving cell or a target cell transmits a handover command to the UE is realized.

As described above, according to the present invention, by realizing a handover method suitable for a 5G communication system that is premised on a beam forming environment (technology), seamless mobility of the terminal is achieved without performance degradation in various scenarios required by the 5G communication system. to achieve a guaranteed effect.

Hereinafter, with reference to FIG. 4, a process of realizing a handover control method (method) according to a preferred embodiment of the present invention will be described from a system point of view.

The terminal device 200 measures the signal from the serving cell (eg, Cell#1) to which it is connected (S1), and if the measured value (eg, RSRP) falls below the threshold, it is determined that handover is required. The measurement information is reported to the serving cell (Cell#1) (S2).

The serving cell (Cell#1), that is, the base station device 100, NB#1, recognizes the terminal device 200 requiring handover (S3), measures the uplink signal of the terminal device 200, and prepares for handover The request is transmitted to each of the neighboring cells (Cells #2, #3, and #4) (S4).

It will be described that the neighboring cells of the base station apparatus 100 and NB#1 are a cell (Cell#2), a cell (Cell#3), and a cell (Cell#4).

In this case, each of the neighboring cells (Cells #2, #3, and #4), according to the preparation request received from the base station apparatus 100 and NB#1, the number of terminals accommodated in it, the amount of traffic, and the radio in use It is determined whether the terminal handover can be accommodated based on the resource usage rate, etc., and if possible, a measurement and handover ready response response may be returned to the base station apparatus 100 (NB#1) (S5).

Accordingly, the base station apparatus 100 (NB#1) returns a measurement and handover preparation possible response to the preparation request among the neighboring cells that have transmitted the uplink signal measurement and handover preparation request of the terminal apparatus 200. A cell is selected as a target candidate cell.

Hereinafter, it is assumed that cells (Cell#2, #3) are selected as candidate target cells among the neighboring cells (Cell#2, #3, #4) of the base station apparatus 100 and NB#1. .

When the target candidate cells (Cell#2, #3) are selected, the base station apparatus 100 (NB#1) transmits an uplink signal to be measured in the target candidate cells (Cell#2, #3). 200) (S6).

In this case, the terminal device 200 will transmit the uplink signal RS according to the command from the base station device 100, NB#1 (S7).

Accordingly, the base station apparatus 100 (NB#1), that is, the serving cell (Cell#1) and the target candidate cell (Cell#2,#3) respectively receive and measure the uplink signal RS of the terminal apparatus 200 . (S8, S9, S10).

Here, the base station apparatus 100, NB#1, has a measurement result measured in the serving cell (Cell#1), for example, a measurement value (eg, RSRP) is a measurement result measured in the target candidate cells (Cell#2,#3), that is, If it is better than the measured value (eg, RSRP), the handover of the terminal device 200 is unnecessary, so it is preferable not to proceed with the handover procedure any longer.

Therefore, hereinafter, for convenience of explanation, a measurement result, for example, a measurement value (eg RSRP) measured in the serving cell (Cell#1) is a measurement result measured in the target candidate cells (Cell#2, #3), that is, a measurement value (eg : RSRP), we will exclude cases that are superior to that of RSRP.

The base station apparatus 100, NB#1, based on the measurement result measured in the target candidate cells (Cells #2, #3) (S11), the terminal apparatus 200 of the target candidate cells (Cells #2, #3) ) determines a target cell to be handed over (S12).

Hereinafter, for convenience of description, it is assumed that the cell (Cell#3) among the target candidate cells (Cell#2, #3) is determined as the target cell.

When the target cell (Cell#3) is determined, the base station apparatus 100 (NB#1) instructs the terminal apparatus 200 to handover to the determined target cell (Cell#3) (S13).

Furthermore, when the target cell Cell#3 is determined, the base station apparatus 100 and NB#1 may notify the target cell Cell#3 of the determination of the target cell for the terminal apparatus 200 (S13). ).

Accordingly, the target cell (Cell#3), that is, the base station (NB#3) fails to transmit the handover command transmitted by the serving cell (Cell#1), that is, the base station apparatuses 100 and NB#1 to the terminal apparatus 200 . The target cell (Cell#3) may transmit a handover command to the terminal device 200 (S15).

The terminal device 200 performs a handover procedure according to a handover command received from the serving cell (Cell#1), that is, the base station device (100, NB#1) or the target cell (Cell#3), that is, the base station (NB#3). A handover procedure from the serving cell (Cell#1) to the target cell (Cell#3) will be performed by transmitting and receiving a signal (signaling, message, etc.) according to (S16).

Hereinafter, a handover control method of a base station apparatus according to a preferred embodiment of the present invention will be described in detail with reference to FIG. 5 .

For convenience of description, a base station (NB#1) forming a cell (Cell#1) will be described as the base station apparatus of the present invention.

The base station (NB#1) of the present invention transfers the terminal 10 reporting measurement information among terminals serving the cell (Cell#1) to a terminal requiring handover from the cell (Cell#1) to the target cell. It can be recognized (S100).

When the base station NB#1 recognizes the terminal 10 requiring handover, it transmits an uplink signal measurement and handover preparation request of the terminal 10 to a neighboring cell (neighboring base station) (S110).

Hereinafter, it will be described that the neighboring cells of the base station NB#1 are a cell (Cell#2), a cell (Cell#3), and a cell (Cell#4).

In this case, when the base station NB#1 recognizes the terminal 10 requiring handover, it transmits the uplink signal measurement and handover preparation request of the terminal 10 to the neighboring cells (Cells #2, #3, #4). ) can be sent to each.

Each of the neighboring cells (Cell#2, #3, #4), according to the preparation request received from the base station apparatus 100, NB#1, the number of terminals accommodated in it, the amount of traffic, the radio resource usage rate in use, etc. Based on the determination whether the terminal handover can be accepted or not, it is possible to return a measurement and handover ready response response to the base station NB#1 if possible.

Accordingly, the base station NB#1 targets a neighboring cell that returns a measurement and handover preparation possible response to the preparation request among the neighboring cells that have transmitted the uplink signal measurement and handover preparation request of the terminal 10 , A candidate cell is selected (S120).

Hereinafter, it is assumed that the cells Cells #2 and #3 are selected as candidate target cells from among the neighboring cells Cells #2, #3, and #4 of the base station NB#1.

When the target candidate cells (Cells #2 and #3) are selected, the base station (NB#1) instructs the terminal (10) to transmit an uplink signal to be measured in the target candidate cells (Cells #2, #3). (S130).

In this case, the terminal 10 will transmit an uplink signal RS according to a command from the base station apparatus 100 and NB#1, and in the target candidate cells Cells #2 and #3, the terminal 10 The uplink signal of RS will be measured and the measurement result will be transmitted to the base station NB#1 (S140).

Accordingly, the base station NB#1 receives the measurement result of measuring the uplink signal, that is, the RS of the terminal 10 from the target candidate cells (Cells #2, #3), and receives the target candidate cells (Cells #2, #3). ), you can check the measurement results.

The base station NB#1, based on the measurement result measured by the target candidate cells Cells #2 and #3, is a target cell to which the terminal 10 will handover among the target candidate cells Cells #2 and #3. is determined (S150).

Specifically, the base station (NB#1), based on the measurement result of measuring the uplink signal (RS) of the terminal 10 in the target candidate cells (Cell#2, #3), for example, the measurement value (eg, RSRP), Among the target candidate cells (Cells #2 and #3), a target candidate cell having the best measurement (eg, RSRP) may be determined as the target cell.

Meanwhile, among the target candidate cells (Cells #2 and #3), the number of target candidate cells having the best measurement result, for example, a measurement value (eg, RSRP) may be not one but two or more.

In this case, the base station NB#1, among two or more target candidate cells with the best measurement result, e.g., a measurement value (eg RSRP), has a smaller radio resource usage rate or is further away from the serving cell (Cell#1). A target candidate cell of the distance may be determined as the target cell.

Hereinafter, for convenience of description, it is assumed that the cell (Cell#3) among the target candidate cells (Cell#2, #3) is determined as the target cell.

When the target cell (Cell#3) is determined, the base station (NB#1) instructs the terminal 10 to handover to the determined target cell (Cell#3), and the terminal 10 serves according to the handover command. A handover procedure is performed from the cell (Cell#1) to the target cell (Cell#3) (S160).

Accordingly, the terminal 10 transmits and receives a signal (signaling, message, etc.) according to the handover procedure according to the handover command, and performs a handover procedure from the serving cell (Cell#1) to the target cell (Cell#3). will do (S170).

Furthermore, when the target cell (Cell#3) is determined, the base station (NB#1) notifies the target cell (Cell#3) of the determination of the target cell for the terminal (10), and the serving cell (Cell#1) That is, it is preferable to enable the target cell (Cell#3) to transmit the handover command to the terminal 10 when the transmission of the handover command transmitted by the base station apparatus 100 and NB#1 to the terminal 10 fails ( S160).

Hereinafter, a handover control method of a terminal device according to a preferred embodiment of the present invention will be described in detail with reference to FIG. 6 .

For convenience of description, as a terminal device of the present invention, the terminal 10 accessing the cell (Cell#1) and using a service will be described.

The terminal 10 of the present invention measures the signal from the connected serving cell (Cell#1) (S200), and when the measured value (eg, RSRP) falls below the threshold, it is determined that handover is required and measured Information may be reported to the serving cell (Cell#1) (S210).

As described above, in the present invention, the serving cell (Cell#1) selects a candidate target cell that can become a target cell during handover of the current terminal 10 among neighboring cells when measurement information is received from the terminal 10 . In addition to the selection, the selected candidate target cell measures the uplink signal to be transmitted from the terminal 10 to predict/prepare that the terminal 10 may be handed over (S220).

In addition, the serving cell (Cell#1) instructs the terminal 10 to transmit an uplink signal (RS) to predict/prepare that a target cell to be handed over is to be determined.

Accordingly, when the terminal 10 receives an uplink signal transmission command for measurement in the target candidate cell from the serving cell (Cell#1), it may transmit an uplink signal RS according to the command (S230). ).

In this case, the uplink signal RS transmitted by the terminal 10 will be received and measured in each of the serving cell (Cell#1) and the target candidate cells (Cell#2, #3).

As described above, the serving cell (Cell#1) is the terminal device 200 among the target candidate cells (Cell#2, #3) based on the measurement result measured in the target candidate cells (Cell#2, #3). , 10) determines a target cell to be handed over (S240).

Hereinafter, for convenience of description, it is assumed that the cell (Cell#3) among the target candidate cells (Cell#2, #3) is determined as the target cell.

In this case, the serving cell (Cell#1) instructs the terminal 10 to handover to the determined target cell (Cell#3).

Accordingly, when a handover command from the serving cell (Cell#1) to the target cell (Cell#3) is received, the terminal 10 transmits and receives a signal (signaling, message, etc.) according to the handover procedure according to the command. A handover procedure from the serving cell (Cell#1) to the target cell (Cell#3) will be performed (S250).

Meanwhile, in the present invention, when the transmission of the handover command transmitted from the serving cell (Cell#1), that is, the base station device (100, NB#1) to the terminal 10, fails, the target cell (Cell#3) issues a handover command. It is defined so that it can be transmitted to the terminal 10 .

Accordingly, even when a handover command from the target cell (Cell#3) to the target cell (Cell#3) is received, the terminal 10 transmits a signal (signaling, message, etc.) according to the handover procedure according to the command. A handover procedure from the serving cell (Cell#1) to the target cell (Cell#3) may be performed by transmitting/receiving (S250).

As described above, according to the handover control method of the present invention, by realizing a handover method suitable for a 5G communication system premised on a beam forming environment (technology), a terminal without performance degradation in various scenarios required by the 5G communication system to ensure the seamless mobility of

The handover control method according to an embodiment of the present invention may be implemented in the form of a program command that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, etc. alone or in combination. The program instructions recorded on the medium may be specially designed and configured for the present invention, or may be known and available to those skilled in the art of computer software. Examples of the computer-readable recording medium include magnetic media such as hard disks, floppy disks and magnetic tapes, optical media such as CD-ROMs and DVDs, and magnetic such as floppy disks. - includes magneto-optical media, and hardware devices specially configured to store and carry out program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine language codes such as those generated by a compiler, but also high-level language codes that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

Although the present invention has been described in detail with reference to preferred embodiments so far, the present invention is not limited to the above-described embodiments, and without departing from the gist of the present invention as claimed in the following claims, the technical field to which the present invention pertains It will be said that the technical idea of the present invention extends to the extent that any person with ordinary skill in the art can make various changes or modifications.

According to the base station apparatus and the terminal apparatus and the handover control method of the apparatus according to the present invention, the limitations of the existing technology are overcome in realizing a new handover method suitable for a 5G communication system premised on a beam forming environment (technology). It is an invention with industrial applicability because the possibility of marketing or business of the applied device, not only the use of the related technology, as well as the extent to which it can be clearly implemented in reality is sufficient.

100: base station device
110: terminal recognition unit 120: linkage unit
130: target cell determining unit
200: terminal device
210: reporting unit 220: transmitting unit
230: handover execution unit

Claims (14)

a terminal recognition unit for recognizing a terminal requesting handover from the serving cell to the target cell;
A neighboring cell that transmits an uplink signal measurement and handover preparation request of the terminal to a neighboring cell located within a predetermined distance from the serving cell, and returns a measurement and handover preparation possible response to the preparation request among the neighboring cells a linkage unit for selecting as a target candidate cell and confirming a measurement result obtained by measuring an uplink signal of the terminal from the selected at least one target candidate cell; and
a target cell determining unit configured to determine a target cell to be handed over by the terminal among the at least one target candidate cell based on the measurement result measured in the at least one target candidate cell;
The target cell determination unit,
When two or more target candidate cells are identified as the target cell to be handed over by the terminal, a target candidate cell having a greater distance from the serving cell among the two or more target candidate cells is determined as the target cell.
delete The method of claim 1,
The linkage is
When the at least one target candidate cell is selected, the base station apparatus according to claim 1 , instructing the terminal to transmit an uplink signal to be measured in the at least one target candidate cell. The method of claim 1,
The target cell determination unit,
and determining, as the target cell, a target candidate cell having the best measurement result among the target candidate cells based on a measurement result of measuring the uplink signal of the terminal in the at least one target candidate cell. 5. The method of claim 4,
The target cell determination unit,
When the number of target candidate cells with the best measurement result among the target candidate cells is two or more, the base station apparatus, characterized in that, among the two or more target candidate cells, a target candidate cell having a greater distance from the serving cell is determined as the target cell. The method of claim 1,
The target cell determination unit,
The base station apparatus, characterized in that by instructing the terminal to handover to the determined target cell, the terminal performs a handover procedure from the serving cell to the target cell according to the handover command. 7. The method of claim 6,
The base station apparatus, characterized in that by notifying the target cell of the determination of the target cell for the terminal, the target cell can transmit the handover command to the terminal when the transmission of the handover command fails. As a terminal device,
a reporting unit for reporting measurement information to the serving cell when handover is requested based on signal measurement from the serving cell;
a transmitter for transmitting an uplink signal to be measured in at least one target candidate cell selected based on the location of the serving cell; and
a handover performing unit configured to perform a handover procedure to a target cell determined from among the at least one target candidate cell based on a measurement result of measuring the uplink signal in the at least one target candidate cell;
The at least one neighbor cell that returns a measurement and handover preparation possible response to the preparation request among neighboring cells located within a predetermined distance from the serving cell to which the uplink signal measurement and handover preparation request of the terminal device is transmitted is selected as a target candidate cell of
When two or more target candidate cells are identified as the target cell, a target candidate cell having a greater distance from the serving cell among the two or more target candidate cells is determined as the target cell. A terminal recognition step of recognizing a terminal requesting handover from the serving cell to the target cell;
A neighboring cell that transmits an uplink signal measurement and handover preparation request of the terminal to a neighboring cell located within a predetermined distance from the serving cell, and returns a measurement and handover preparation possible response to the preparation request among the neighboring cells a candidate cell interworking step of selecting as a target candidate cell and confirming a measurement result obtained by measuring an uplink signal of the terminal from the selected at least one target candidate cell; and
a target cell determining step of determining a target cell to be handed over by the terminal among the at least one target candidate cell based on the measurement result measured in the at least one target candidate cell;
The target cell determination step is
When two or more target candidate cells are identified as target cells to be handed over by the terminal, among the two or more target candidate cells, a target candidate cell having a greater distance from the serving cell is determined as the target cell. Handover control method. delete 10. The method of claim 9,
and instructing the terminal to transmit an uplink signal to be measured in the at least one target candidate cell when the at least one target candidate cell is selected. 10. The method of claim 9,
The target cell determination step is
determining, as the target cell, a target candidate cell having the best measurement result among the target candidate cells based on a measurement result of measuring an uplink signal of the terminal in the at least one target candidate cell;
The method further comprising the step of determining, as the target cell, a target candidate cell having a greater distance from the serving cell among the two or more target candidate cells when the number of target candidate cells having the best measurement result among the target candidate cells is two or more A handover control method of a base station apparatus according to 10. The method of claim 9,
instructing the terminal to handover to the determined target cell, so that the terminal performs a handover procedure from the serving cell to the target cell according to the handover command; and
The method further comprising the step of notifying the target cell of the determination of the target cell for the terminal so that the target cell can transmit the handover command to the terminal when transmission of the handover command fails of handover control method. A method for controlling handover of a terminal device, comprising:
a reporting step of reporting measurement information to the serving cell when handover is requested based on signal measurement from the serving cell;
a transmitting step of transmitting an uplink signal to be measured in at least one target candidate cell selected based on the location of the serving cell; and
a handover performing step of performing a handover procedure to a target cell determined from among the at least one target candidate cell based on a measurement result of measuring the uplink signal in the at least one target candidate cell;
The at least one neighbor cell that returns a measurement and handover preparation possible response to the preparation request among neighboring cells located within a predetermined distance from the serving cell to which the uplink signal measurement and handover preparation request of the terminal device is transmitted is selected as a target candidate cell of
When two or more target candidate cells are identified as the target cell, a target candidate cell having a greater distance from the serving cell among the two or more target candidate cells is determined as the target cell.

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