Method and apparatus for performing handover procedure in wireless communication system

Abstract

A method for performing a handover is disclosed. The method for performing a handover, which is performed by a base station, comprises the steps of: receiving a measurement control report from a terminal; determining a handover on the basis of the measurement control report from the terminal; and transmitting a handover request to a target base station, wherein the handover request includes sub-band full duplex (SBFD)-related information of the terminal.

Description

Method and device for performing a handover procedure in a wireless communication system

[0001] The present disclosure relates to a handover procedure in a wireless communication system, and more particularly, to a method and apparatus for performing a handover procedure in a wireless communication system supporting sub-band full duplex (SBFD).

[0002] This application was carried out with the support of the following national research and development project.

[0003] Assignment ID 1711134273

[0004] Assignment number 2021-0-00749-001

[0005] Ministry of Science and ICT

[0006] Project Management Agency Name: Information and Communications Technology Planning and Evaluation Institute

[0007] Research Project Name: Broadcasting and Communications Industry Technology Development (R&D, Informatization)

[0008] Research Project Title: Development of a Platform for 5G+ Communication System RF Performance Verification

[0009] Contribution rate 1 / 1

[0010] Name of the project performing organization: Korea Industrial Technology Testing Institute

[0011] Research period: April 1, 2021 - December 31, 2023

[0012] A communication system may include a core network, base stations (e.g., macro base stations, small base stations, relays, etc.), terminals, etc. Communication between the base stations and terminals may be performed based on various radio access technologies (RATs) (e.g., 4G communication technology, 5G communication technology, WiBro (wireless broadband) technology, WLAN (wireless local area network) technology, WPAN (wireless personal area network) technology, etc.).

[0013] Handover is one of the mobility management technologies in wireless communication systems. Handover is a technology that allows a terminal to disconnect from its original source base station and establish a connection with a new target base station when moving from one cell or base station to another. Handover ensures that terminals in wireless communication systems receive stable service.

[0014] Meanwhile, various radio resource allocation methods are being discussed to improve the efficiency of radio resource management and enhance the coverage of base stations and terminals in 5G mobile communication systems. In addition to dividing uplink and downlink resources in the time domain using conventional time division duplex (TDD) systems, technologies are being discussed that allow simultaneous transmission and reception of downlink and uplink signals within the same time interval.

[0015] Sub-band Full Duplex (SBFD) supports simultaneous transmission and reception of uplink and downlink. According to SBFD, uplink and downlink can be allocated by subband in the frequency domain. SBFD is called cross division duplex (XDD). In XDD, 'X' stands for time or frequency. SBFD differs from the existing TDD and FDD in that it separates the uplink and downlink using both the time domain and the frequency domain. The frame structure in SBFD mode can be much more flexible than in the existing TDD and FDD. However, in SBFD mode, the guard band is insufficient, which causes signal interference problems.

[0016] According to at least one embodiment, a method and apparatus for performing handover utilizing a subband full-duplex communication mode are disclosed.

[0017] In one aspect, a handover method performed by a base station is disclosed.

[0018] The disclosed method comprises the steps of: receiving a measurement control report of a terminal; determining a handover based on the measurement control report of the terminal; and transmitting a handover request to a target base station, wherein the handover request may include sub-band full duplex (SBFD) related information of the terminal.

[0019] The SBFD-related information of the terminal may include at least one of whether the terminal supports the SBFD mode, information related to the SBFD subband supported by the terminal, information related to the uplink transmission power of the terminal, information related to repetitive transmission in the SBFD mode, information related to CLI (Cross link interference), and information related to SI (Self interference).

[0020] The information related to the SBFD sub-band supported by the terminal may include at least one of information on the SBFD time domain where the SBFD sub-band is located, the range of the UL sub-band supported by the terminal, the range of the DL sub-band supported by the terminal, and an indicator indicating one of a plurality of SBFD sub-band configurations.

[0021] The method further includes a step of obtaining SBFD-related information of the terminal from the terminal; and a step of providing allocation information of an SBFD time domain and an UL subband to the terminal, wherein the measurement control report can be received through the UL subband in the SBFD time domain.

[0022] The method further includes a step of acquiring SBFD-related information of neighboring base stations, and in the step of determining the handover, the base station may determine at least one of the neighboring base stations as a target base station based on the SBFD-related information of the terminal and the SBFD-related information of the neighboring base stations.

[0023] The SBFD-related information of neighboring base stations may include at least one of information on whether each neighboring base station supports the SBFD mode, information on SBFD subbands supported by each neighboring base station, CLI-related information acquired by each neighboring base station, SI-related information acquired by each neighboring base station, information on UL repetition-related information in the SBFD mode supported (or used) by each neighboring base station, and information on DL repetition-related information in the SBFD mode supported by each neighboring base station.

[0024] The step of determining a handover based on the measurement control report of the terminal includes the step of determining whether a handover margin is satisfied based on the measurement control report of the terminal and the step of determining a handover if the handover margin is satisfied, wherein the handover margin can be determined based on whether the base station supports UL repetition transmission in SBFD mode and whether the target base station supports UL repetition transmission in SBFD mode.

[0025] If the base station supports UL repetition transmission in SBFD mode and the target base station does not support UL repetition transmission in SBFD mode, the handover margin may be determined to be larger than the handover margin of a legacy system. A legacy system may be a communication system before the SBFD mode was introduced or before the SBFD mode was introduced.

[0026] If the base station does not support UL repetition transmission in SBFD mode and the target base station supports UL repetition transmission in SBFD mode, the handover margin may be determined to be smaller than the handover margin of the legacy system.

[0027] The above measurement control report may include SBFD related information of the terminal.

[0028] The method further includes a step of receiving a handover request response from the target base station, wherein the handover request response includes SBFD-related information of the target base station, and the SBFD-related information of the target base station may include at least one of information on whether the target base station supports an SBFD mode, information related to SBFD subbands supported by the target base station, CLI-related information acquired by the target base station, SI-related information acquired by the target base station, information related to UL repetition transmission in the SBFD mode supported by the target base station, and information related to DL repetition transmission in the SBFD mode supported by the target base station.

[0029] The method includes a step of transmitting a message triggering a handover to the terminal, wherein the message triggering the handover may include SBFD-related information of the target base station.

[0030] The message triggering the above handover may be an RRCReconfiguration message.

[0031] In another aspect, a base station is provided, which includes a communication unit and a processor. The processor performs the steps of: receiving a measurement control report of a terminal; determining a handover based on the measurement control report of the terminal; and transmitting a handover request to a target base station, wherein the handover request may include information related to sub-band full duplex (SBFD) of the terminal.

[0032] In another aspect, a handover method performed by a terminal is disclosed.

[0033] The disclosed method comprises the steps of transmitting a measurement control report to a source base station; receiving a message triggering a handover from the source base station; and performing a random access to a target base station identified by the message triggering the handover, wherein the message triggering the handover may include SBFD-related information of the target base station.

[0034] Random access to the above target base station can be performed via the UL sub-band.

[0035] The message triggering the above handover may be an RRCReconfiguration message.

[0036] The method further includes the steps of providing SBFD-related information of the terminal to the source base station; and the step of obtaining allocation information of an SBFD time domain and an UL sub-band from the source base station, wherein the measurement control report can be transmitted through an UL sub-band in the SBFD time domain.

[0037] The step of performing random access to the target base station includes the step of determining PRACH transmission power for random access to the target base station and the step of performing random access using the determined PRACH transmission power, wherein the PRACH transmission power may be determined based on at least one of whether the source base station supports UL repeated transmission in SBFD mode, the number of UL repeated transmissions in SBFD mode for the source base station, whether the target base station supports UL repeated transmission in SBFD mode, and the number of UL repeated transmissions in SBFD mode for the target base station.

[0038] If the source base station supports UL repeated transmission in SBFD mode and the target base station does not support UL repeated transmission in SBFD mode, the PRACH transmission power may be set to be greater than the PRACH transmission power in a legacy system.

[0039] If the source base station does not support UL repeated transmission in SBFD mode and the target base station supports UL repeated transmission in SBFD mode, the PRACH transmission power may be set to be smaller than the PRACH transmission power in a legacy system.

[0040] The PUSCH transmission power for the target base station may be determined based on at least one of whether the source base station supports UL repeated transmission in SBFD mode, the number of UL repeated transmissions in SBFD mode for the source base station, whether the target base station supports UL repeated transmission in SBFD mode, and the number of UL repeated transmissions in SBFD mode for the target base station.

[0041] If the source base station supports UL repeated transmission in SBFD mode and the target base station does not support UL repeated transmission in SBFD mode, the PUSCH transmission power may be set to be greater than the PUSCH transmission power in a legacy system.

[0042] If the source base station does not support UL repeated transmission in SBFD mode and the target base station supports UL repeated transmission in SBFD mode, the PUSCH transmission power may be set to be smaller than the PUSCH transmission power in a legacy system.

[0043] The PUCCH transmission power for the target base station may be determined based on at least one of whether the source base station supports UL repeated transmission in SBFD mode, the number of UL repeated transmissions in SBFD mode for the source base station, whether the target base station supports UL repeated transmission in SBFD mode, and the number of UL repeated transmissions in SBFD mode for the target base station.

[0044] If the source base station supports UL repeated transmission in SBFD mode and the target base station does not support UL repeated transmission in SBFD mode, the PUCCH transmission power may be set to be greater than the PUCCH transmission power in a legacy system.

[0045] If the source base station does not support UL repeated transmission in SBFD mode and the target base station supports UL repeated transmission in SBFD mode, the PUCCH transmission power may be set to be smaller than the PUCCH transmission power in a legacy system.

[0046] In another aspect, a terminal including a communication unit and a processor is provided.

[0047] The processor performs the steps of: transmitting a measurement control report to a source base station; receiving a message triggering a handover from the source base station; and performing a random access to a target base station identified by the message triggering the handover, wherein the message triggering the handover may include SBFD-related information of the target base station.

[0048] According to at least one embodiment, the SBFD-related information of the terminal is provided to the source base station, so that the UL subband in the SBFD mode can be utilized in the handover procedure. According to at least one embodiment, the SBFD-related information of the terminal is provided to the target base station, and the SBFD-related information of the target base station can be provided to the terminal in the handover procedure. Accordingly, the terminal can transmit a signal to the target base station using the UL subband in the handover procedure. According to at least one embodiment, the delay time required until a handover decision can be shortened because the UL subband is used in the measurement control reporting procedure. According to at least one embodiment, the delay time required until an RRC handover is completed can be shortened because the UL subband is used in the process of the terminal performing random access to the target base station. According to at least one embodiment, the accumulated transmit power gain of the terminal can be increased because the terminal performs repeated transmission using the UL subband in the handover procedure.

[0049] FIG. 1 is a diagram illustrating a wireless communication system according to an exemplary embodiment.

[0050] Figure 2 is a block diagram exemplarily showing the configuration of a communication node constituting a communication system.

[0051] Figure 3 is a diagram illustrating an example of a 5G network architecture.

[0052] Figure 4 is a diagram showing the legacy frame structure in TDD mode.

[0053] FIG. 5 is a diagram showing a frame structure in SBFD mode according to an exemplary embodiment.

[0054] Figure 6 is a flowchart showing the process by which a source base station acquires SBFD-related information and schedules SBFD resources.

[0055] Figure 7 is a flowchart illustrating a process of performing a handover procedure according to an exemplary embodiment.

[0056] Figure 8 illustrates a case where a terminal transmits a measurement control report using a legacy TDD frame.

[0057] Figure 9 illustrates a case where a terminal transmits a measurement control report using a UL subband in SBFD mode.

[0058] Figure 10 illustrates a case where a terminal performs random access to a target base station using a legacy TDD frame.

[0059] Figure 11 illustrates a case where a terminal performs random access to a target base station using a UL subband in SBFD mode.

[0060] Figure 12 is a flowchart illustrating a process of performing conditional handover (CHO) according to an exemplary embodiment.

[0061] Figure 13 shows the change in transmission power of a terminal (120-1) during the process of performing a handover procedure in a legacy system.

[0062] Figure 14 shows the change in transmission power during the process in which a terminal (120-1) performs a handover procedure from an SBFD base station to a non-SBFD base station.

[0063] Figure 15 shows the change in transmission power during the process in which a terminal (120-1) performs a handover procedure from a non-SBFD base station to an SBFD base station.

[0064] The present invention is susceptible to various modifications and embodiments. Specific embodiments are illustrated and described in detail in the drawings. However, this is not intended to limit the present invention to specific embodiments, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention.

[0065] While terms such as "first" and "second" may be used to describe various components, these components should not be limited by these terms. These terms are used solely to distinguish one component from another. For example, without departing from the scope of the present invention, a first component could be referred to as a "second component," and similarly, a second component could also be referred to as a "first component." The term "and / or" includes any combination of multiple related items listed or any one of multiple related items listed.

[0066] When a component is referred to as being "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components intervening. Conversely, when a component is referred to as being "directly connected" or "connected" to another component, it should be understood that there are no other components intervening.

[0067] The terminology used in this application is only used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, it should be understood that the terms "comprise" or "have" indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0068] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0069] Hereinafter, with reference to the attached drawings, preferred embodiments of the present invention will be described in more detail. In order to facilitate an overall understanding in describing the present invention, identical reference numerals will be used for identical components in the drawings, and redundant descriptions of identical components will be omitted.

[0070] Table 1 shows the abbreviations used in this disclosure.

[0071] 약어전체 이름3GPP3rd Generation Partnership ProjectACKAcknowledgementAFApplication FunctionAMFAccess and Mobility Management FunctionAUSFAuthentication Server FunctionBWPBandwidth PartC-RNTICell RNTICSIChannel State InformationCSI-RSChannel State Information Reference SignalCLICross link InterferenceCEControl ElementDCIDownlink Control InformationIEInformation elementMACMedium Access ControlNSSFNetwork Slicing Selection FunctionNEFNetwork Exposure FunctionNRFNF Repository FunctionPCFPolicy Control FunctionPDCCHPhysical Downlink Control ChannelPDSCHPhysical Downlink Shared ChannelPDUProtocol Data UnitPRACHPhysical Random Access ChannelPT-RSPhase Tracking Reference SignalPUCCHPhysical Uplink Control ChannelPUSCHPhysical Uplink Shared ChannelRARandom AccessRACHRandom Access ChannelRANRadio Access NetworkRBResource BlockRRCRadio Resource ControlRSRPReference Signal Received PowerRSRQReference Signal Received QualityRSSIReceived Signal Strength IndicatorSBFDSub-Band Full DuplexSISelfInterferenceUEUser EquipmentDLDownlinkULUplinkRARRandom Access ResponseRRMRadio Resource ManagementRRCRadio Resource ControlQoSQuality of ServiceDRBData Radio BearerDAPSDual Active Protocol StackTDDTime Division DuplexingFDDFrequency Division Duplexing

[0072] FIG. 1 is a diagram illustrating a wireless communication system (100) according to an exemplary embodiment.

[0073] Referring to FIG. 1, a wireless communication system (100) may be composed of a plurality of communication nodes (110-1, 110-2, 110-3, 120-1, 120-2, 120-3). Here, a communication node refers to a node capable of transmitting and receiving signals in the wireless communication system (100), and each of the plurality of communication nodes (110-1, 110-2, 110-3, 120-1, 120-2, 120-3) may support at least one communication protocol. For example, each of the plurality of communication nodes (110-1, 110-2, 110-3, 120-1, 120-2, 120-3) may support cellular communication (e.g., long term evolution (LTE), advanced LTE-A, 5G NR, 5G-Advanced, etc. as defined in the 3rd generation partnership project (3GPP) standard).

[0074] For example, each of the plurality of communication nodes (110-1, 110-2, 110-3, 120-1, 120-2, 120-3) can support a communication protocol based on CDMA (code division multiple access), a communication protocol based on WCDMA (wideband CDMA), a communication protocol based on TDMA (time division multiple access), a communication protocol based on FDMA (frequency division multiple access), a communication protocol based on OFDM (orthogonal frequency division multiplexing), a communication protocol based on OFDMA (orthogonal frequency division multiple access), a communication protocol based on SC (single carrier)-FDMA, a communication protocol based on NOMA (non-orthogonal multiple access), a communication protocol based on SDMA (space division multiple access), a communication protocol based on SBFD (sub-band full duplex), etc.

[0075] A plurality of communication nodes (110-1, 110-2, 110-3, 120-1, 120-2, 120-3) may include a plurality of base stations (110-1, 110-2, 110-3) and a plurality of terminals (120-1, 120-2, 120-3). Each of the base stations (110-1, 110-2, 110-3) may form a cell. The cell may include a small cell, a macro cell, a pico cell, a femto cell, etc., but the embodiment is not limited thereto. For example, a first terminal (120-1) may belong to the coverage of a first base station (110-1), a second terminal (120-2) may belong to the coverage of a second base station (110-2), and a third terminal (120-3) may belong to the coverage of a third base station (110-3). In Fig. 1, each terminal belonging to the coverage of each base station is represented one by one, but this is for convenience of explanation, and multiple terminals may belong to the coverage of a base station. In addition, when the location of the terminal changes as the terminal moves, the terminal may form a wireless connection with another base station through a handover.

[0076] The plurality of base stations (110-1, 110-2, 110-3) may be referred to as gNodeB (gNB), NodeB, evolved NodeB, base transceiver station (BTS), radio base station, radio transceiver, access point, access node, road side unit (RSU), radio remote head (RRH), transmission point (TP), transmission and reception point (TRP), relay node, etc. The plurality of base stations (110-1, 110-2, 110-3) may form a radio access network (RAN). The radio access network may be connected to a core network.

[0077] Each of the plurality of terminals (120-1, 120-2, 120-3) may be referred to as a terminal, an access terminal, a mobile terminal, a station, a subscriber station, a mobile station, a portable subscriber station, a node, a device, etc.

[0078] The communication protocol support ranges of the plurality of base stations (110-1, 110-2, 110-3) may differ from each other. For example, some of the plurality of base stations (110-1, 110-2, 110-3) may support the SBFD mode, while others may not support the SBFD mode. Similarly, the communication protocol support ranges of the plurality of terminals (120-1, 120-2, 120-3) may also differ from each other. For example, some of the plurality of terminals (120-1, 120-2, 120-3) may support the SBFD mode, while others may not support the SBFD mode.

[0079] Fig. 2 is a block diagram exemplarily showing the configuration of a communication node (200) constituting a communication system. At least some of the communication nodes (110-1, 110-2, 110-3, 120-1, 120-2, 120-3) shown in Fig. 1 may correspond to the communication node (200) shown in Fig. 2.

[0080] Referring to FIG. 2, a communication node (200) may include at least one processor (210), a memory (220), and a transmission / reception device (230) that is connected to a network and performs communication. In addition, the communication node (200) may further include an input interface device (240), an output interface device (250), a storage device (260), etc. Each component included in the communication node (200) may be connected by a bus (270) and communicate with each other.

[0081] The processor (210) can execute program commands stored in at least one of the memory (220) and the storage device (260). The processor (210) may refer to a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor in which methods according to embodiments of the present invention are performed. Each of the memory (220) and the storage device (260) may be configured with at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory (220) may be configured with at least one of a read-only memory (ROM) and a random access memory (RAM).

[0082] Figure 3 is a diagram illustrating an example of a 5G network architecture.

[0083] Referring to FIG. 3, the 5G network architecture may include NSSF providing a network slicing control solution, NEF providing a network function opening solution, NRF providing an NF interworking control solution within a 5G network, PCF providing a data packet flow policy control solution, UDM providing a user information and policy management solution, AMF providing a network access and mobility management solution, SMF providing a terminal / network session management solution, UPF providing a base station-to-base station user packet routing and terminal connectivity provision solution, a radio access network (RAN), and user equipment (UE).

[0084] The N1 reference point is defined to transmit signaling between the UE and the AMF, the N2 reference point is defined to connect between the RAN's access node and the AMF, and the N3 reference point is defined to connect between the RAN's access node and the UPF.

[0085] Hereinafter, for convenience of explanation, the first base station (110-1) shown in FIG. 1 is referred to as a source base station, and the first terminal (120-1) is referred to as a terminal.

[0086] Figure 4 is a diagram showing the legacy frame structure in TDD mode.

[0087] Referring to FIG. 4, a time interval (40) may be defined in the time domain. The time interval may also be referred to as a time unit. The time interval (40) may correspond to any one of a slot, a symbol, and a subframe. As another example, the time interval (40) may be defined to include multiple slots. As another example, the time interval (40) may be defined to include multiple symbols. As another example, the time interval (40) may be defined to include multiple subframes.

[0088] In TDD mode, downlink resources may be allocated in the first to fourth time intervals (40, 41, 42, 43). Downlink signals may be transmitted in the first to fourth time intervals (40, 41, 42, 43). Uplink resources may be allocated in the fifth time interval (44). Downlink signals may be transmitted in the fifth time interval (44). According to the legacy frame structure illustrated in FIG. 4, even when the terminal (120-1) needs to transmit an uplink signal between the first to fourth time intervals (40, 41, 42, 43), the terminal (120-1) may wait until the fifth time interval (44) to which the uplink resources are allocated arrives before transmitting the uplink signal. This may cause a delay (latency) until the terminal (200-1) transmits the uplink signal.

[0089] FIG. 5 is a diagram showing a frame structure in SBFD mode according to an exemplary embodiment.

[0090] Referring to FIG. 5, in the SBFD mode, uplink resources and downlink resources can be allocated simultaneously in the first to fourth time intervals (40, 41, 42, 43). In the first to fourth time intervals (40, 41, 42, 43), UL subbands for uplink transmission and DL subbands for downlink transmission can be allocated simultaneously. The time interval in which UL subbands and DL subbands are allocated simultaneously to enable subband full-duplex communication can be referred to as an SBFD time interval.

[0091] Although not shown in FIG. 5, there may be a time period to which downlink is allocated prior to the first to fourth time intervals (40, 41, 42, 43) corresponding to the SBFD time period. Through the downlink allocated prior to the SBFD time period, the base station can transmit scheduling information for the SBFD time period and SBFD subband to the terminal.

[0092] In FIG. 5, the first to fourth time intervals (40, 41, 42, and 43) may correspond to the SBFD time domain. The SBFD time domain may be defined to include at least one slot. As another example, the SBFD time domain may be defined to include at least one symbol. As another example, the SBFD time domain may be defined to include at least one subframe.

[0093] Each of the UL subband and the DL subband may include at least one RB. For example, each of the UL subband and the DL subband may include RBs arranged contiguously. As another example, each of the UL subband and the DL subband may include RBs arranged non-contiguously in at least part.

[0094] Each of the UL subbands and the DL subbands may include at least one BWP. For example, each of the UL subbands and the DL subbands may include at least one legacy BWP. As another example, each of the UL subbands and the DL subbands may include at least one BWP separately defined to support SBFD.

[0095] As described above, SBFD subbands can be configured within a TDD mode carrier for SBFD mode operation. The SBFD subbands can include UL subbands and DL subbands. In FIG. 5, the UL subband is exemplarily shown as being located in the middle of the carrier. However, the embodiment is not limited thereto. For example, the UL subband can be located at the edge of the carrier. In another example, the UL subband can be located at a location other than the exact center of the carrier.

[0096] Additionally, a guard period may be placed between the SBFD time domain and the non-SBFD time domain to which SBFD is not applied. Each of the SBFD time domain and the non-SBFD time domain may include at least one symbol.

[0097] The time and frequency positions of the SBFD subbands can be configured and indicated semi-statically. Alternatively, the time and frequency positions of the SBFD subbands can be configured and indicated dynamically.

[0098] In SBFD mode, the use efficiency of radio resources can be improved by flexibly distributing uplink and downlink resources. In addition, the delay can be reduced because the time that the terminal (120-1) waits for uplink signal transmission and the time that the terminal (120-1) waits for downlink signal reception are reduced. In addition, in SBFD mode, the terminal (120) repeatedly transmits UL signals and repeatedly receives DL signals in multiple time intervals (40, 41, 42, 43), thereby increasing the transmission gain of the UL and DL signals, and expanding the coverage of the source base station (110-1) and the terminal (120-1).

[0099] However, in SBFD mode, a sufficiently large guard band may not be provided between the UL and DL subbands. This may increase the likelihood of problems caused by CLI or SI in SBFD mode.

[0100] The embodiment described below describes a method of utilizing SBFD mode in a handover procedure of a terminal (120-1).

[0101] Figure 6 is a flowchart showing the process in which a source base station (110-1) obtains SBFD-related information and schedules SBFD resources.

[0102] Referring to FIG. 6, in step S10, the source base station (110-1) can obtain SBFD-related information of the terminal (120-1) from the terminal (120-1). The SBFD-related information of the terminal (120-1) can include at least one of whether the terminal (120-1) supports the SBFD mode, information related to SBFD subbands supported (or used) by the terminal (120-1), information related to uplink transmission power of the terminal (120-1), information related to repeated transmission in SBFD mode, CLI-related information, and SI-related information.

[0103] The SBFD subband-related information may include information on the SBFD time domain where the SBFD subband is located. The SBFD subband-related information of the terminal (120-1) may include the range of the UL subband supported (or used) by the terminal and the range of the DL subband supported (or used) by the terminal. The range of the UL subband supported (or used) by the terminal may include the starting point of the UL subband. The range of the UL subband may include the number of RBs included in the UL subband or BWP information included in the UL subband. The range of the DL subband supported (or used) by the terminal may include the starting point of the DL subband. The range of the DL subband may include the number of RBs included in the DL subband or BWP information included in the DL subband. The SBFD subband-related information may include an indicator or index indicating one of the configurations for the predetermined SBFD subband. For example, the terminal (120-1) may use any one of a plurality of SBFD subband configurations included in the SBFD subband configuration set. The SBFD subband-related information may include an indicator or index indicating any one of the plurality of SBFD subband configurations.

[0104] Information about repeated transmission in SBFD mode may include at least one of whether UL repeated transmission is performed in SBFD mode, the number of UL repeated transmissions, whether DL repeated transmission is performed, and the number of DL repeated transmissions.

[0105] At least some of the SBFD-related information of the terminal (120-1) may not be transmitted in step S10, but may be transmitted to the source base station (110-1) through a measurement control report of the handover procedure.

[0106] The source base station (110-1) can obtain SBFD-related information of the terminal (120-1) based on UE capability information received from the terminal (120-1). The source base station (110-1) can transmit a UE capability inquiry message to the terminal (120-1) and receive a UE capability information message from the terminal (120-1). The UE capability information can include an IE for SBFD-related information of the terminal (120-1). As another example, the source base station (110-1) can obtain SBFD-related information by receiving separate signaling for transmitting SBFD-related information from the terminal (120-1). As another example, the source base station (110-1) can receive an IE including SBFD-related information of the terminal (120-1) or terminal capability information including SBFD-related information of the terminal (120-1) from the AMF.

[0107] At step S20, the source base station (110-1) may schedule SBFD resources. The source base station (110-1) may schedule SBFD resources based on SBFD-related information of the terminal (120-1). If the source base station (110-1) does not support the SBFD mode, the source base station (110-1) may not allocate SBFD resources separately. In addition, if the terminal (120-1) does not support the SBFD mode, the source base station (110-1) may not allocate a UL subband of the SBFD mode to the terminal (120-1).

[0108] The source base station (110-1) can transmit scheduling information of SBFD resources to the terminal (120-1). The scheduling information of SBFD resources can be broadcast via a system information block. As another example, the scheduling information of SBFD resources can be provided to the terminal (120-1) via at least one of RRC signaling, upper layer signaling, MAC CE, and DCI.

[0109] For example, the source base station (110-1) can transmit information about the SBFD time domain to the terminal (120-1) using a slot format. In this case, in addition to the downlink slot (D), uplink slot (U), and flexible slot (F) of the legacy NR, a new slot including the UL sub-band and the DL sub-band of the SBFD can be provided. The source base station (110-1) can provide the terminal (120-1) with information about the slot format for activating the UL sub-band and the DL sub-band of the SBFD using at least one of the tdd-UL-DL-ConfigurationCommon IE, the tdd-UL-DL-ConfigurationDedicated IE, and the DCI. However, the embodiment is not limited thereto. The source base station (110-1) can configure and signal a separate IE indicating the SBFD time domain. The IE indicating the SBFD time domain can include information about the number of slots and the slot start point of the SBFD time domain. As another example, an IE indicating an SBFD time domain may include information about the number of symbols in the SBFD time domain and the symbol start point. As another example, an IE indicating an SBFD time domain may include information about the number of subframes in the SBFD time domain and the subframe start point.

[0110] The source base station (110-1) can provide information about the UL sub-band and / or the DL sub-band to the terminal (120-1) in the SBFD time domain. For example, the source base station (110-1) can provide information about the starting point of the UL sub-band and / or the DL sub-band, the number of consecutive RBs included in the UL sub-band and / or the DL sub-band to the terminal (120-1). As another example, the information about the UL sub-band and / or the DL sub-band can include BWP information included in the UL sub-band and / or the DL sub-band, and BWP information set to define the UL sub-band and / or the DL sub-band.

[0111] At step S30, the source base station (110-1) can obtain SBFD-related information of neighboring base stations (110-2, 110-3). The source base station (110-1) can obtain SBFD-related information of neighboring base stations (110-2, 110-3) from the neighboring base stations (110-2, 110-3) by using the Xn interface. In addition, the source base station (110-1) can provide its own SBFD-related information to the neighboring base stations (110-2, 110-3) by using the Xn interface. As another example, the source base station (110-1) can obtain SBFD-related information of neighboring base stations (110-2, 110-3) from the AMF by using the N2 interface. In addition, the SBFD-related information of the source base station (110-1) can be provided to the neighboring base stations (110-2, 110-3) by the AMF.

[0112] The source base station (110-1) may also obtain SBFD-related information of neighboring base stations (110-2, 110-3) or target base stations as part of the measurement configuration.

[0113] The SBFD-related information of the source base station (110-1) may include at least one of information on whether the source base station (110-1) supports the SBFD mode, information on SBFD subbands supported (or used) by the source base station (110-1), CLI-related information acquired by the source base station (110-1) from the terminal (120-1), SI-related information acquired by the source base station (110-1) from the terminal (120-1), information on UL repetition-related transmission in the SBFD mode supported by the source base station (110-1), and information on DL repetition-related transmission in the SBFD mode supported by the source base station (110-1).

[0114] SBFD subband related information may include information about the SBFD time domain in which the SBFD subband is located. SBFD subband related information of the source base station (110-1) may include the range of the UL subband supported (or used) by the source base station (110-1) and the range of the DL subband supported (or used) by the source base station (110-1).

[0115] The SBFD sub-band related information may include an indicator or index indicating one of the configurations for a predetermined SBFD sub-band.

[0116] The SBFD-related information of the neighboring base stations (110-2, 110-3) may include at least one of information on whether each of the neighboring base stations (110-2, 110-3) supports the SBFD mode, information on the SBFD subbands supported (or used) by each of the neighboring base stations (110-2, 110-3), CLI-related information acquired by each of the neighboring base stations (110-2, 110-3), SI-related information acquired by each of the neighboring base stations (110-2, 110-3), information on UL repetition-related information in the SBFD mode supported (or used) by each of the neighboring base stations (110-2, 110-3), and information on DL repetition-related information in the SBFD mode supported by each of the neighboring base stations (110-2, 110-3).

[0117] The SBFD subband-related information may include information about the SBFD time domain in which the SBFD subband is located. The SBFD subband-related information of each of the neighboring base stations (110-2, 110-3) may include the range of the UL subband supported (or used) by each of the neighboring base stations (110-2, 110-3) and the range of the DL subband supported (or used) by each of the neighboring base stations (110-2, 110-3).

[0118] The SBFD sub-band related information may include an indicator or index indicating one of the configurations for a predetermined SBFD sub-band.

[0119] The SBFD-related information of the terminal (120-1) acquired by the source base station (110-1) in step S10 and the SBFD-related information of neighboring base stations (110-2, 110-3) acquired in step S30 can be utilized by the source base station (110-1) to prepare or proceed with the handover procedure.

[0120] The source base station (110-1) can determine at least one target base station based on at least one of its own traffic load, time and / or frequency resource status, measurement control report of the terminal (120-1), SBFD-related information of the terminal (120-1), SBFD-related information of neighboring base stations (110-2, 110-3), and traffic load of the neighboring base stations (110-2, 110-3).

[0121] For example, if the terminal (120-1) does not support the SBFD mode, the source base station (110-1) can determine the target base station similarly to the conventional method without considering the SBFD mode. If the terminal (120-1) supports the SBFD mode, the source base station (110-1) can determine whether to utilize the SBFD mode in the handover procedure based on the SBFD-related information of the neighboring base stations (110-2, 110-3) and the SBFD-related information of the terminal (120-1).

[0122] The terminal (120-1) can utilize the UL subband of the SBFD mode when transmitting a measurement control report in the handover procedure. As another example, the terminal (120-1) can utilize the UL subband of the SBFD mode when transmitting and receiving signals with the target base station in the handover procedure. To this end, the source base station (110-1) can select a base station among the neighboring base stations (110-2, 110-3) that can support the SBFD mode for the terminal (120-2) as the target base station so that the terminal (120-1) can transmit and receive signals with the target base station using the UL subband of the SBFD mode.

[0123] The source base station (110-1) can determine a target base station by considering information on UL sub-bands that the terminal (120-1) can support in the SBFD mode and information on UL sub-bands that neighboring base stations (110-2, 110-3) can support in the SBFD mode. The source base station (110-1) can determine a base station among the neighboring base stations (110-2, 110-3) that can allocate a UL sub-band that the terminal (120-1) can use as a target base station.

[0124] The source base station (110-1) can determine the target base station based on at least one of the CLI measurement information of the terminal (120-1), the SI measurement information of the terminal (120-1), the channel measurement information for the source base station (110-1) of the terminal (120-1), the channel measurement information for the neighboring base stations (110-2, 110-3) of the terminal (120-1), and the traffic load of the neighboring base stations (110-2, 110-3).

[0125] As another example, the target base station is determined by the AMF, and the source base station (110-1) can obtain information about the target base station from the AMF. The AMF can determine the target base station based on the SBFD-related information of the terminal (120-1) and the SBFD-related information of neighboring base stations (110-2, 110-3).

[0126] Figure 7 is a flowchart illustrating a process of performing a handover procedure according to an exemplary embodiment.

[0127] Before the handover procedure illustrated in FIG. 7 is initiated, the source base station (110-1) can obtain SBFD-related information of the terminal (120-1) and SBFD-related information of the target base station (110-2) in advance by performing steps S10 and S30 of FIG. 6. However, the embodiment is not limited thereto. As another example, the source base station (110-1) can also obtain SBFD-related information of the target base station (110-2) from the AMF in step S100 of FIG. 7.

[0128] Referring to FIG. 7, mobility control information by AMF can be provided to base stations (110-1, 110-2) at step S100. The source base station (110-1) can obtain at least some of the SBFD-related information of the target base station (110-2) in advance through the Xn interface. For example, the source base station (110-1) can obtain information in advance about whether the target base station (110-2) supports SBFD through the Xn interface. As another example, the source base station (110-1) can obtain at least some of the SBFD-related information of the target base station (110-2) from the AMF.

[0129] A handover event may occur at step S101. The handover event may occur due to movement of the terminal (120-1), etc.

[0130] In step S102, the terminal (120-1) can transmit a Measurement Control and Report to the source base station (110-1). If the terminal (120-1) supports the SBFD mode, the source base station (110-1) can allocate SBFD resources to the terminal (120-1) in step S20 of FIG. 6. The terminal (120-1) can transmit a Measurement Control and Report to the source base station (110-1) using the SBFD resources. However, even if the terminal (120-1) supports the SBFD mode, if the CLI and / or SI are severe, the terminal (120-1) may be restricted from using the UL subband in the SBFD mode.

[0131] When the terminal (120-1) performs measurement control reporting using the UL subband in SBFD mode, the delay time (T) shown in FIG. 7 d1 ) can be reduced. For example, when the terminal (120-1) uses a legacy TDD frame, the delay time (T) from the occurrence of a handover event to transmitting a measurement control report is reduced because the frequency with which the terminal (120-1) is allocated UL resources is low. d1 ) may be long. On the other hand, when the terminal (120-1) uses the UL sub-band using the SBFD mode, the delay time (T) is relatively long because the UL resources are allocated frequently. d1 ) may be more likely to decrease.

[0132] Figure 8 illustrates a case where a terminal (120-1) transmits a measurement control report using a legacy TDD frame. Figure 9 illustrates a case where a terminal (120-1) transmits a measurement control report using a UL subband in SBFD mode.

[0133] In FIGS. 8 to 11 below, “D” represents a DL slot, “U” represents a UL slot, and “S” represents a special slot.

[0134] Referring to FIG. 8, it can be assumed that the terminal (120-1) receives a reference signal in a first time interval (52) to which downlink resources are allocated. In addition, it can be assumed that the terminal (120-1) determines that a handover event has occurred in the first time interval (52). The reference signal may include a CSI-RS, a PT-RS, etc. The terminal (120-1) may transmit a measurement control report based on the measurement result of the reference signal. The terminal (120-1) may wait without performing a measurement control report in the second time interval (54) because UL resources are not allocated. The terminal (120-1) may transmit a measurement control report after the start point of the third time interval (56) to which uplink resources are allocated. Therefore, the terminal (120-1) may wait without performing a measurement control report for a time interval that is at least the second time interval (54). This may cause a delay in the measurement control report. Therefore, a delay may occur before the source base station (110-1) decides to perform a handover. If the terminal (120-1) moves quickly or the channel environment of the terminal (120-1) changes rapidly, the delay in the handover procedure may prevent smooth wireless communication service.

[0135] Referring to FIG. 9, it can be assumed that the terminal (120-1) receives a reference signal using the DL subband in the first time interval (62). In addition, it can be assumed that the terminal (120-1) determines that a handover event has occurred in the first time interval (62). The terminal (120-1) can transmit a measurement control report using the UL subband in the second time interval (64). Of course, the terminal (120-1) can also perform a measurement control report using the UL subband in the third time interval (66). Referring to FIG. 9, compared to the case of FIG. 8, the UL resource allocation required for the terminal (120-1) to perform a measurement control report is performed flexibly and quickly, thereby reducing the delay occurring during the handover process.

[0136] Referring back to FIG. 7, the measurement control report of step S102 may include SBFD-related information of the terminal (120-1). The SBFD-related information of the terminal (120-1) included in the measurement control report may further include at least one of whether the terminal (120-1) supports the SBFD mode, the maximum number of UL subbands supported by the terminal (120-1), the range of UL subbands supported by the terminal (120-1), uplink transmission power-related information of the terminal (120-1), CLI-related information, and SI-related information.

[0137] In step S104, the source base station (110-1) may determine a handover based on the measurement control report of the terminal (120-1). The source base station (110-1) may determine a handover based on at least one of the downlink channel measurement result of the terminal (120-1), the uplink channel measurement result based on the SRS transmitted by the terminal, the SBFD-related information of the terminal (120-1), the SBFD-related information of neighboring base stations (110-2, 110-3), the traffic load of the source base station (110-1), and the traffic load of the neighboring base stations (110-2, 110-3).

[0138] For example, if the source base station (110-1) supports repetitive transmission in SBFD mode and the target base station (110-2) does not support repetitive transmission in SBFD mode, the source base station (110-1) can compensate for the handover margin by considering the gain difference of repetitive transmission. Based on the SBFD-related information of the neighboring base stations (110-2, 110-3), it can be determined whether a candidate base station that can become the target base station supports repetitive transmission in SBFD mode.

[0139] For example, the source base station (110-1) can compensate the handover margin as in mathematical expression 1.

[0140]

[0141] In mathematical expression 1 represents the handover margin when the difference in repeated transmissions between the source base station (110-1) and the target base station (110-2) is not taken into account. represents a handover margin that takes into account the difference in repeated transmissions between the source base station (110-1) and the target base station (110-2). represents a handover margin correction value considering repetitive transmission in SBFD mode of the source base station (110-1).

[0142] If the source base station (110-1) supports repetitive transmission in SBFD mode and the target base station (110-2) does not support repetitive transmission in SBFD mode, the source base station (110-1) can set the handover margin higher than before. This ensures service quality even if the terminal (120-1) is connected to the target base station (110-2) that does not support SBFD.

[0143] As another example, if the source base station (110-1) does not support repetitive transmission in SBFD mode and the target base station (110-2) supports repetitive transmission in SBFD mode, the source base station (110-1) can compensate for the handover margin by considering the gain difference of repetitive transmission. Based on the SBFD-related information of the neighboring base stations (110-2, 110-3), it can be determined whether a candidate base station that can become the target base station supports repetitive transmission in SBFD mode.

[0144] For example, the source base station (110-1) can compensate the handover margin as in mathematical expression 2.

[0145]

[0146] In mathematical expression 1 represents the handover margin when the difference in repeated transmissions between the source base station (110-1) and the target base station (110-2) is not taken into account. represents a handover margin that takes into account the difference in repeated transmissions between the source base station (110-1) and the target base station (110-2). represents a handover margin correction value considering repetitive transmission in SBFD mode of the target base station (110-2).

[0147] If the source base station (110-1) does not support repetitive transmission in SBFD mode and the target base station (110-2) supports repetitive transmission in SBFD mode, the source base station (110-1) can set the handover margin lower than before. This allows the terminal (120-1) to perform an early handover to the target base station (110-2) that supports SBFD, thereby ensuring high service quality.

[0148] The source base station (110-1) can determine the target base station (110-2). If the terminal (120-1) supports the SBFD mode, the source base station (110-1) can determine the target base station (110-2) as a base station that can perform communication with the terminal (120-1) using the SBFD mode.

[0149] The source base station (110-1) may determine a base station that does not support the SBFD mode as the target base station (110-2) even if the terminal (120-1) supports the SBFD mode. For example, if a delay is allowed for the handover of the terminal (120-1) in consideration of the service quality required for the terminal (120-1), the traffic load for the terminal (120-1), etc., the source base station (110-1) may determine a base station that does not support the SBFD mode for the terminal (120-1) as the target base station (110-2). As another example, even if there is no base station among the neighboring base stations (110-2, 110-3) that can support the SBFD mode for the terminal (120-1), the source base station (110-1) may determine a base station that does not support the SBFD mode for the terminal (120-1) as the target base station (110-2). As another example, if it is determined that the use of the SBFD mode is inappropriate based on the CLI measurement report and SI measurement report of the terminal (120-1), the source base station (110-1) may determine a base station that does not support the SBFD mode as the target base station (110-2).

[0150] Even if the terminal (120-1) supports the SBFD mode and the target base station (110-2) can support the SBFD mode for the terminal (120-1), the source base station (110-1) may determine that the use of the SBFD mode is unnecessary in step S112 described below. Alternatively, the source base station (110-1) may restrict the use of the SBFD mode based on at least one of the CLI measurement result and the SI measurement result of the terminal (120-1). In this case, the source base station (110-1) may not transmit the SBFD-related information of the terminal (120-1) to the target base station (110-2).

[0151] At step S106, the source base station (110-1) may transmit a handover request (HANDOVER REQUEST) to the target base station (110-2). The handover request may include the cell ID of the target base station (110-2), the C-RNTI of the terminal (120-1), RRM configuration, a rule for mapping the current QoS flow to the DRB, etc.

[0152] According to an exemplary embodiment, the handover request may further include SBFD-related information of the terminal (110-2). The SBFD-related information of the terminal (110-2) may be included in the handover request as part of the terminal capability information. As another example, the SBFD-related information of the terminal (110-2) may be included in the handover request as a separate IE. As described above, the SBFD-related information of the terminal (110-2) may further include at least one of whether the terminal (120-1) supports the SBFD mode, the maximum number of UL subbands supported by the terminal (120-1), the range of UL subbands supported by the terminal (120-1), CLI-related information, and SI-related information.

[0153] If the source base station (110-1) restricts the use of the UL sub-band of the terminal (120-1) in the handover procedure or determines that the use of the UL sub-band is unnecessary, all or part of the SBFD-related information of the terminal (120-1) may be omitted in the handover request.

[0154] In step S108, the target base station (110-2) may perform admission control for the handover request. The target base station (110-2) may determine whether to admit the handover request. For example, the target base station (110-2) may perform slice-aware admission control. If the PDU session is connected to an unsupported slice, the target base station (110-2) may reject the corresponding PDU session. The target base station (110-2) may determine whether to allow the terminal (120-1) to use the UL subband in the SBFD mode during the handover procedure. The target base station (110-2) may allow the terminal (120-1) to use the UL subband in the SBFD mode during the handover procedure while approving the handover request. As another example, the target base station (110) may approve the handover request but may not allow the terminal (120-1) to use the UL subband in the SBFD mode during the handover procedure.

[0155] In step S110, the target base station (110-2) may transmit a handover request acknowledgement (HANDOVER REQUEST ACKNOWLEDGE). The source base station (110-1) may receive the handover request acknowledgement. The handover request acknowledgement may include a new C-RNTI of the terminal (120-1) used in the cell of the target base station (110-2), a cell ID of the target base station (110-2), security algorithm identifiers of the target base station (110-2), a dedicated RACH resource set of the target base station (110-2), connections between RACH resources, terminal-specific CSI-RS configuration information, common RACH resources, system information of the target base station (110-2), etc.

[0156] According to an exemplary embodiment, the handover request response may further include SBFD related information of the target base station (110-2). The SBFD-related information of the target base station (110-2) may include at least one of information on whether the target base station supports the SBFD mode, information on the SBFD subbands supported (or used) by the target base station (110-2), CLI-related information acquired by the target base station (110-2), SI-related information acquired by the target base station (110-2), information on UL repetition in the SBFD mode supported (or used) by the target base station (110-2), and information on DL repetition in the SBFD mode supported (or used) by the target base station (110-2). If the target base station (110-2) approves the handover request but does not allow the terminal (120-1) to use the UL subbands of the SBFD mode in the handover procedure, the handover request response may not include the SBFD-related information of the target base station (110-2).

[0157] At step S112, the source base station (110-1) can trigger a handover by transmitting an RRCReconfiguration message to the terminal (120-1). The RRCReconfiguration message can include the cell ID of the target base station (110-2), a new C-RNTI, security algorithm identifiers of the target base station (110-2), a dedicated RACH resource set of the target base station (110-2), connections between RACH resources, terminal-specific CSI-RS configuration information, common RACH resources, system information of the target base station (110-2), etc.

[0158] The RRC reset message may further include SBFD-related information of the target base station (110-2). The RRC reset message may include at least one of the SBFD time domain used by the target base station (110-2), the number of UL subbands used by the target base station (110-2), the range of the UL subbands, the number of DL subbands, and the range of the DL subbands. The SBFD time domain used by the target base station (110-2), the number of UL subbands, and at least some of the UL may also be included in the RRC reset message as part of information about the dedicated RACH resource set or common RACH resources of the target base station (110-2).

[0159] When a handover is triggered, the terminal (120-1) can perform a random access procedure for the target base station (110-2) based on the RRC reset message. If the RRC reset message includes SBFD-related information of the target base station (110-2), the terminal (120-1) can perform a random access procedure using the UL subband.

[0160] At step S114, the source base station (110-1) may transmit an SN STATUS TRANSFER message to the target base station (110-2). In the case of DAPS handover, the source base station (110-1) may transmit an EARLY STATUS TRANSFER message instead of the SN STATUS TRANSFER message.

[0161] At step S116, the target base station (110-2) can store (buffer) user data received from the source base station (110-1).

[0162] At step S118, the terminal (120-1) can complete the RRC handover procedure by synchronizing with the target base station (110-2) and transmitting an RRCReconfigurationComplete message to the target base station (110-2). In the case of DAPS handover, even after the terminal (120-1) receives the RRC reset message at step S112, the terminal (120-1) can maintain the connection with the source base station (110-1). In the case of DAPS handover, the terminal (120-1) can release the connection with the source base station (110-1) after receiving an explicit release instruction from the target base station (110-2). After step S118, further procedures such as a path switch of user data may be performed.

[0163] At step S118, the terminal (120-1) can perform a random access procedure for the target base station (110-2). During this process, the terminal (120-1) can transmit a random access message to the target base station (110-2). The terminal (120-1) can receive a random access response message from the target base station (110-2). The terminal (120-1) can transmit a random access completion message to the target base station (110-2).

[0164] When the terminal (120-1) performs a random access procedure using the UL subband and / or DL ​​subband in the SBFD mode, the delay time (T) shown in FIG. 7 d2 ) can be reduced. For example, when the terminal (120-1) uses a legacy TDD frame, the time that the terminal (120-1) waits to be allocated UL resources to transmit a random access message, the time that the terminal (120-1) waits to be allocated DL resources to receive a random access response message, and the time that the terminal (120-1) waits to be allocated UL resources to transmit a random access complete message may be relatively large.

[0165] However, if the terminal (120-1) uses the UL sub-band and / or the DL sub-band of the SBFD mode, at least one of the delay time required for the terminal (120-1) to transmit a random access message, the delay time required for the terminal (120-1) to receive a random access response message, and the delay time required for the terminal (120-1) to transmit a random access complete message can be reduced.

[0166] Fig. 10 illustrates a case where a terminal (120-1) performs random access to a target base station (110-2) using a legacy TDD frame. Fig. 11 illustrates a case where a terminal (120-1) performs random access to a target base station (110-2) using a UL subband in SBFD mode.

[0167] Referring to FIG. 10, it can be assumed that a handover is triggered in a first time interval (72) to which downlink resources are allocated. Although the handover is triggered, the terminal (120-1) may wait until uplink resources are allocated to secure a random access occasion. The terminal (120-1) may wait in a second time interval (74). After the start point of the third time interval (76), the terminal (120-1) may be allocated uplink resources, perform random access to the target base station (110-2), and transmit an RRCReconfigurationComplete message to the target base station (110-2). Accordingly, the terminal (120-1) may wait for a time interval that is at least as long as the second time interval (74). This may delay the completion of the RRC handover. Accordingly, a delay may occur until the completion of the RRC handover. If the terminal (120-1) moves quickly or the channel environment of the terminal (120-1) changes quickly, wireless communication service may not be provided smoothly due to delay in the handover procedure.

[0168] Referring to FIG. 11, the terminal (120-1) can assume that a handover is triggered in the first time interval (82). The terminal (120-1) can perform a random access procedure for the target base station (110-2) using the UL sub-band in the second time interval (84) and transmit an RRC reset completion message to the target base station (110-2) to complete the RRC handover. As another example, the terminal (120-1) can perform a random access procedure for the target base station (110-2) using the UL sub-band in the third time interval (86) or in the second time interval (84) and the third time interval (86). Since the terminal (120-1) completes the RRC handover without waiting until the UL time interval, the time required to complete the RRC handover can be shortened by the third time interval (86). Therefore, the delay occurring during the handover process can be reduced.

[0169] Fig. 12 is a flowchart illustrating a process for performing a conditional handover (CHO) according to an exemplary embodiment. In describing the embodiment of Fig. 12, descriptions of parts similar to or overlapping with those of Fig. 7 are omitted.

[0170] Referring to FIG. 12, in step S202, the terminal (120-1) may transmit a measurement control report to the source base station (110-1). The terminal (120-1) may utilize the UL subband of the SBFD mode when transmitting the measurement control report in the handover procedure. In this case, the time required for CHO determination may be shortened as described with reference to FIG. 9. The measurement control report may include SBFD-related information of the terminal (120-1). The SBFD-related information of the terminal (120-1) included in the measurement control report may further include at least one of whether the terminal (120-1) supports the SBFD mode, SBFD subband-related information, uplink transmission power-related information of the terminal (120-1), CLI-related information, and SI-related information.

[0171] In steps S206 and S207, the source base station (110-1) can transmit a handover request to at least one candidate target base station (110-2, 110-3).

[0172] The manner in which the source base station (110-1) determines at least one candidate target base station may be similar to the manner in which the source base station (110-1) determines a target base station described with reference to FIG. 7.

[0173] According to an exemplary embodiment, the handover request may further include SBFD-related information of the terminal (110-2). The SBFD-related information of the terminal (110-2) may be included in the handover request as part of the terminal capability information. As another example, the SBFD-related information of the terminal (110-2) may be included in the handover request as a separate IE. As described above, the SBFD-related information of the terminal (110-2) may further include at least one of whether the terminal (120-1) supports SBFD mode, SBFD subband-related information, CLI-related information, and SI-related information.

[0174] In steps S210 and S211, the source base station (110-1) may receive a handover request response from at least one candidate target base station (110-2, 110-3). According to an exemplary embodiment, the handover request response may further include SBFD-related information of at least one candidate target base station (110-2, 110-3). The handover request response may include SBFD subband-related information supported (or used) by at least one candidate target base station (110-2, 110-3).

[0175] At step S212, the source base station (110-1) can trigger a handover by transmitting an RRCReconfiguration message to the terminal (120-1). The RRCReconfiguration message may further include SBFD-related information of at least one candidate target base station (110-2, 110-3).

[0176] At step S214, the terminal (120-1) can transmit an RRC reset completion message to the source base station (110-1).

[0177] At step S216, the terminal (120-1) can evaluate whether the predetermined CHO condition is satisfied. If the CHO condition is satisfied, at step S218, the terminal (120-1) can disconnect from the source base station (110-1) and synchronize with the target base station (110-2). The terminal (120-1) can perform random access to the target base station (110-2) and, at step S220, transmit an RRC reconfiguration complete message to the target base station (110-2) to complete the RRC handover procedure.

[0178] Terminal (120-1) can utilize the UL sub-band during random access to the target base station (110-2). In this case, the handover time can be shortened, as shown in FIG. 11.

[0179] In SBFD mode, the terminal (120-1) can increase transmission gain through repeated transmission. In addition, in step S118 of FIG. 7 and step S220 of FIG. 12, the terminal (120-1) can perform a random access procedure for the target base station (110-2). The terminal (120-1) can adjust the transmission power for the PRACH during the process of performing the random access procedure. The terminal (120-1) can adjust the transmission power for the PRACH for the target base station (110-2) based on whether the source base station (110-1) supports UL repeated transmission in SBFD mode and whether the target base station (110-2) supports UL repeated transmission in SBFD mode.

[0180] Mathematical expression 3 shows how the terminal (120-1) determines the transmission power for PRACH.

[0181]

[0182] In mathematical expression 3 represents the transmission power for PRACH in UL BWP b of carrier f of serving cell c based on DL RS of serving cell c at transmission occasion i. represents the maximum output power on carrier f of serving cell c at transmission opportunity i. represents the path loss in UL BWP b of carrier C calculated by the terminal (120-1) based on the DL RS associated with PRACH transmission in serving cell c. represents the PRACH target reception power in UL BW P b of carrier f of serving cell c.

[0183] The terminal (120-1) may determine the transmission power for the PRACH for the target base station (110-2) differently from that shown in Equation 3 based on at least one of whether the source base station (110-1) supports UL repeat transmission in SBFD mode, the number of UL repeat transmissions in SBFD mode for the source base station (110-1), whether the target base station (110-2) supports UL repeat transmission in SBFD mode, and the number of UL repeat transmissions in SBFD mode for the target base station (110-2).

[0184] As a first example, if the source base station (110-1) supports UL repeated transmission in SBFD mode and the target base station (110-2) does not support UL repeated transmission in SBFD mode, the terminal (120-1) may determine the transmission power for PRACH to be higher than that shown in Equation 3 during a random access process for the target base station (110-2).

[0185] In the first example, the terminal (120-1) is represented by Equation 3. can be adjusted higher than the existing one. For example, the terminal (120-1) One of the RRC parameters that determines and At least one of them can be corrected. is a parameter for the initial random access preamble power for the 4-step RA (random access) type. is a parameter for the initial random access preamble power for the 2-step RA (random access) type.

[0186] Below, the terminal (120-1) An example of how to correct the terminal (120-1) is described. mgA-PreambleReceivedTargetPower can be calibrated in a similar way to how it is calibrated.

[0187] For example, terminal (120-1) can be corrected as shown in mathematical expression 4.

[0188]

[0189] In mathematical formula 4 Represents parameter values ​​for the initial random access preamble power for a 4-step RA type determined based on the decision method in legacy systems. represents a correction value considering the repetitive transmission gain of the source base station (110-1). represents a parameter value for the initial random access preamble power for the 4-step RA type of the target base station (110-2) corrected by taking into account the repetitive transmission gain of the source base station (110-1).

[0190] As described above, when a terminal (120-1) performs a handover from a source base station (110-1) that supports UL repetition transmission of SBFD to a target base station (110-2) that does not support UL repetition transmission of SBFD, the terminal (120-1) may determine a parameter for the initial random access preamble power for the 4-step RA type to be higher than a value determined by the existing determination method, taking into account the repetition transmission gain at the source base station (110-1). Through this, the terminal (120-1) may maintain the quality of the UL signal also for the target base station (110-2).

[0191] As a second example, if the source base station (110-1) does not support UL repeated transmission in SBFD mode and the target base station (110-2) supports UL repeated transmission in SBFD mode, the terminal (120-1) may determine the transmission power for PRACH to be lower than that shown in Equation 3 during a random access process for the target base station (110-2).

[0192] In the second example, the terminal (120-1) is represented by Equation 3. can be adjusted to be lower than the existing one. For example, the terminal (120-1) One of the RRC parameters that determines and At least one of them can be corrected. is a parameter for the initial random access preamble power for the 4-step RA (random access) type. is a parameter for the initial random access preamble power for the 2-step RA (random access) type.

[0193] Below, the terminal (120-1) An example of how to correct the terminal (120-1) is described. In a similar way to how it compensates for can be corrected.

[0194] For example, terminal (120-1) can be corrected as shown in mathematical expression 5.

[0195]

[0196] In mathematical expression 5 Represents parameter values ​​for the initial random access preamble power for a 4-step RA type determined based on the decision method in legacy systems. represents a correction value considering the repetitive transmission gain of the target base station (110-2). represents a parameter value for the initial random access preamble power for the 4-step RA type of the target base station (110-2) corrected by taking into account the repetitive transmission gain of the target base station (110-2).

[0197] As described above, when a terminal (120-1) performs a handover from a source base station (110-1) that does not support UL repeated transmission of SBFD to a target base station (110-2) that supports UL repeated transmission of SBFD, the terminal (120-1) may determine a parameter for the initial random access preamble power for the 4-step RA type to be lower than a value determined by the existing determination method, taking into account the repeated transmission gain at the target base station (110-2). Through this, the terminal (120-1) may reduce power consumption.

[0198] As a third example, if both the source base station (110-1) and the target base station (110-2) support UL repetition transmission in the SBFD mode, but the number of UL repetition transmissions for the source base station (110-1) is set higher than the number of UL repetition transmissions for the target base station (110-2), the terminal (120-1) may determine the transmission power for the PRACH to be higher than that shown in Equation 3 during the random access process for the target base station (110-2). In this process, the terminal (120-1) may determine the transmission power for the PRACH to be higher than that shown in Equation 4, similarly to that shown in Equation 4. and It can be set larger than in legacy systems.

[0199] As a fourth example, if both the source base station (110-1) and the target base station (110-2) support UL repetition transmission in the SBFD mode, but the number of UL repetition transmissions for the source base station (110-1) is set smaller than the number of UL repetition transmissions for the target base station (110-2), the terminal (120-1) may determine the transmission power for the PRACH to be lower than that shown in Equation 3 during the random access process for the target base station (110-2). In this process, the terminal (120-1) may determine the transmission power for the PRACH to be lower than that shown in Equation 5, similarly to that shown in Equation 5. and At least one of them can be determined to be smaller than in the legacy system.

[0200] Mathematical expression 3 describes the transmission power for the PRACH. In addition to the transmission power for the PRACH, terminal (120-1) may also adjust the transmission power for other UL channels. For example, terminal (120-1) may adjust at least one of the transmission power for the PUSCH and the transmission power for the PUCCH.

[0201] In the first and third cases mentioned above, the terminal (120-1) may set at least one of the transmission power for the PUSCH and the transmission power for the PUCCH to be greater than that in the legacy system. In the second and fourth cases mentioned above, the terminal (120-1) may set at least one of the transmission power for the PUSCH and the transmission power for the PUCCH to be less than that in the legacy system.

[0202] Mathematical expression 6 shows how to determine the transmission power for PUSCH in a legacy system.

[0203]

[0204] The parameters shown in Equation 6 are defined in 3GPP TS 38.213 V16.13.0 section 7.1.1. Among these, represents the transmission power for PUSCH in the UL BWP b of carrier f of serving cell c based on the DL RS of serving cell c at transmission occasion i, and the parameter set configuration of index j, and the PUSCH power control adjustment state of index l. represents the maximum output power of the terminal. Among the parameters in Equation 6, Is can depend on.

[0205] In the first and third cases described above, the terminal (120-1) is as shown in mathematical expression 4. By setting the transmission power for the PUSCH for the target base station (110-2) higher than in the legacy system, the transmission power can be set higher than in the legacy system.

[0206] In the second and fourth cases described above, the terminal (120-1) is as shown in mathematical expression 5. By setting the transmit power for the PUSCH for the target base station (110-2) to be lower than in the legacy system, the transmit power can be set lower than in the legacy system.

[0207] Figure 13 shows the change in transmission power of a terminal (120-1) during the process of performing a handover procedure in a legacy system.

[0208] Figure 14 shows the change in transmission power during the process in which a terminal (120-1) performs a handover procedure from an SBFD base station to a non-SBFD base station.

[0209] Figure 15 shows the change in transmission power during the process in which a terminal (120-1) performs a handover procedure from a non-SBFD base station to an SBFD base station.

[0210] Referring to FIGS. 13 and 14, when a terminal (120-1) performs a handover procedure in a legacy system, the PRACH transmission power can be further increased when the terminal (120-1) performs a handover from an SBFD base station to a non-SBFD base station. This allows the UL transmission quality to be maintained even if the UL repetition transmission supported by the source base station (110-1) is not supported by the target base station (110-2).

[0211] Referring to FIGS. 13 and 15, when a terminal (120-1) performs a handover procedure in a legacy system, the PRACH transmission power can be further reduced when the terminal (120-1) performs a handover from a non-SBFD base station to an SBFD base station. Through this, the terminal (120-1) can reduce power consumption by taking into account the repetitive transmission gain for the target base station (120-2).

[0212] Hereinafter, a method and apparatus for performing a handover procedure in a mobile communication system according to exemplary embodiments have been described with reference to FIGS. 1 to 15. According to at least one embodiment, SBFD-related information of a terminal is provided to a source base station, so that a UL subband in SBFD mode can be utilized in the handover procedure. According to at least one embodiment, SBFD-related information of the terminal can be provided to a target base station, and SBFD-related information of the target base station can be provided to the terminal in the handover procedure. Accordingly, the terminal can transmit a signal to the target base station using the UL subband in the handover procedure. According to at least one embodiment, the delay time required until a handover decision can be shortened by using the UL subband in the measurement control reporting procedure. According to at least one embodiment, the delay time required until an RRC handover is completed can be shortened by using the UL subband in the process of the terminal performing random access to the target base station. According to at least one embodiment, the accumulated transmission power gain of the terminal can be increased by performing repeated transmissions by the terminal using the UL subband in the handover procedure.

[0213] Based on the description of the various embodiments of the present disclosure above, it will be apparent to those skilled in the art that the methods and / or processes of the present invention, and their steps, can be implemented by hardware, software, or any combination of hardware and software suitable for a specific application. The hardware may include a general-purpose computer and / or a dedicated computing device, or a specific computing device or a specific aspect or component of a specific computing device. The processes may be implemented by one or more processors, such as a microprocessor, a controller, such as a microcontroller, an embedded microcontroller, a microcomputer, an arithmetic logic unit (ALU), a digital signal processor, such as a programmable digital signal processor, or other programmable devices, having internal and / or external memory. Additionally, or alternatively, the processes may be implemented in an application specific integrated circuit (ASIC), a programmable gate array, such as a field programmable gate array (FPGA), a programmable logic unit (PLU), or Programmable Array Logic (PAL), or any other device capable of executing instructions and responding thereto, or any other device or combination of devices that may be configured to process electronic signals. The processing device may execute an operating system (OS) and one or more software applications running on the operating system. Furthermore, the processing device may access, store, manipulate, process, and generate data in response to the execution of the software.For ease of understanding, the processing unit is sometimes described as being used alone. However, those skilled in the art will appreciate that the processing unit may include multiple processing elements and / or multiple types of processing elements. For example, the processing unit may include multiple processors, or a processor and a controller. Additionally, other processing configurations, such as parallel processors, are also possible.

[0214] Software may include computer programs, codes, instructions, or a combination of one or more of these, which may configure a processing device to perform a desired operation or, independently or collectively, command the processing device. The software and / or data may be permanently or temporarily embodied in any type of machine, component, physical device, virtual equipment, computer storage media or devices, or transmitted signal waves, for interpretation by the processing device or for providing instructions or data to the processing device. The software may also be distributed over networked computer systems and stored or executed in a distributed manner. The software and data may be stored on one or more machine-readable recording media.

[0215] Furthermore, the objects of the technical solution of the present invention or the parts contributing to prior arts may be implemented in the form of program instructions that can be executed through various computer components and recorded on a machine-readable medium. The machine-readable medium may include program instructions, data files, data structures, etc., alone or in combination. The program instructions recorded on the machine-readable recording medium may be those specially designed and configured for the embodiment or may be known and available to those skilled in the art of computer software. Examples of the machine-readable recording medium include magnetic media such as hard disks, floppy disks, and magnetic tapes, optical media such as CD-ROMs, DVDs, and Blu-rays, magneto-optical media such as floptical disks, and hardware devices specially configured to store and execute program instructions such as ROMs, RAMs, and flash memories. Examples of program instructions include, but are not limited to, machine code, byte code, as well as high-level language code that can be executed by a computer using an interpreter, etc., which can be created using a structured programming language such as C, an object-oriented programming language such as C++, or a high-level or low-level programming language (assembler, hardware description languages, and database programming languages ​​and technologies), which can be stored and compiled or interpreted for execution on any of the aforementioned devices, as well as a heterogeneous combination of processors, processor architectures, or combinations of different hardware and software, or any other machine capable of executing program instructions.

[0216] Accordingly, in one aspect of the present invention, when the methods and combinations thereof described above are performed by one or more computing devices, the methods and combinations thereof may be implemented as executable code that performs each step. In another aspect, the methods may be implemented as systems that perform the steps, and the methods may be distributed in various ways across devices, or all functions may be integrated into a single dedicated, standalone device or other hardware. In yet another aspect, the means for performing the steps associated with the processes described above may comprise any of the hardware and / or software described above. All such sequential combinations and arrangements are intended to fall within the scope of the present disclosure.

[0217] For example, the hardware device described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa. The hardware device may include a processor, such as an MPU, a CPU, a GPU, or a TPU, coupled with a memory, such as a ROM / RAM, for storing program instructions and configured to execute the instructions stored in the memory, and may include a communication unit capable of transmitting and receiving signals with an external device. In addition, the hardware device may include a keyboard, a mouse, or other external input devices for receiving instructions written by developers.

[0218] Although the present invention has been described above with specific details such as specific components and limited embodiments and drawings, these are provided only to help a more general understanding of the present invention, and the present invention is not limited to the above embodiments, and a person having ordinary knowledge in the technical field to which the present invention pertains can make various modifications and variations from this description.

[0219] Therefore, the spirit of the present invention should not be limited to the embodiments described above, and all modifications equivalent to or equivalent to the appended claims of this disclosure, as well as those equivalent to or equivalent to the claims, are considered to fall within the scope of the spirit of the present invention. For example, appropriate results may be achieved even if the described techniques are performed in a different order from the described method, and / or components of the described systems, structures, devices, circuits, etc. are combined or combined in a different form from the described method, or are replaced or substituted by other components or equivalents.

[0220] Such equivalent or equivalent modifications would include, for example, logically equivalent methods capable of producing the same results as those obtained by carrying out the method according to the present invention, and the spirit and scope of the present invention should not be limited by the examples set forth above, but should be understood in the broadest sense permissible by law.

Claims

1. In the handover method performed by the base station, A step of receiving a measurement control report of a terminal; A step of determining handover based on the measurement control report of the terminal; and A step of transmitting a handover request to a target base station, The above handover request is a handover method including information related to SBFD (sub-band full duplex) of the terminal.

2. In paragraph 1, A handover method in which the SBFD-related information of the terminal includes at least one of whether the terminal supports SBFD mode, information related to SBFD subbands supported by the terminal, information related to uplink transmission power of the terminal, information related to repetitive transmission in SBFD mode, information related to CLI (Cross link interference) and information related to SI (Self interference).

3. In paragraph 2, A handover method in which information related to SBFD sub-bands supported by the terminal includes at least one of information on an SBFD time domain in which the SBFD sub-band is located, a range of UL sub-bands supported by the terminal, a range of DL sub-bands supported by the terminal, and an indicator indicating one of a plurality of SBFD sub-band configurations.

4. In paragraph 1, A step of obtaining SBFD-related information of the terminal from the terminal; and Further comprising a step of providing the terminal with allocation information of the SBFD time domain and the UL sub-band, The above measurement control report is a handover method received through the UL sub-band in the above SBFD time domain.

5. In paragraph 4, Further comprising a step of obtaining SBFD-related information of neighboring base stations, A handover method for determining at least one of the neighboring base stations as a target base station based on the SBFD-related information of the terminal and the SBFD-related information of the neighboring base stations in the step of determining the handover.

6. In paragraph 5, A handover method in which the SBFD-related information of neighboring base stations includes at least one of information on whether each neighboring base station supports the SBFD mode, information on SBFD subbands supported by each neighboring base station, CLI-related information acquired by each neighboring base station, SI-related information acquired by each neighboring base station, information on UL repetition-related information in the SBFD mode supported (or used) by each neighboring base station, and information on DL repetition-related information in the SBFD mode supported by each neighboring base station.

7. In paragraph 1, The step of determining handover based on the measurement control report of the above terminal is: A step of determining whether a handover margin is satisfied based on a measurement control report of the terminal and a step of determining a handover if the handover margin is satisfied, A handover method in which the handover margin is determined based on whether the base station supports UL repetition transmission in SBFD mode and whether the target base station supports UL repetition transmission in SBFD mode.

8. In paragraph 7, A handover method in which the base station supports UL repetition transmission in SBFD mode and the target base station does not support UL repetition transmission in SBFD mode, and the handover margin is determined to be larger than the handover margin of the legacy system.

9. In paragraph 7, A handover method in which the handover margin is determined to be smaller than the handover margin of a legacy system when the base station does not support UL repetition transmission in SBFD mode and the target base station supports UL repetition transmission in SBFD mode.

10. In paragraph 1, The above measurement control report is a handover method including SBFD related information of the terminal.

11. In paragraph 1, Further comprising the step of receiving a handover request response from the target base station, The above handover request response includes SBFD-related information of the target base station, A handover method in which the SBFD-related information of the target base station includes at least one of information on whether the target base station supports the SBFD mode, information on SBFD subbands supported by the target base station, CLI-related information acquired by the target base station, SI-related information acquired by the target base station, information on UL repetition-related information in the SBFD mode supported by the target base station, and information on DL repetition-related information in the SBFD mode supported by the target base station.

12. In paragraph 11, A step of transmitting a message triggering a handover to the terminal, A handover method in which a message triggering the handover includes SBFD-related information of the target base station.

13. In paragraph 12, A handover method in which the message that triggers the above handover is an RRCReconfiguration message.

14. Ministry of Communications; and In a base station including a processor, The processor performs the steps of: receiving a measurement control report of a terminal; determining a handover based on the measurement control report of the terminal; and transmitting a handover request to a target base station. The above handover request is a base station including information related to SBFD (sub-band full duplex) of the terminal.

15. In a handover method performed by a terminal, A step of transmitting a measurement control report to a source base station; A step of receiving a message triggering a handover from the source base station; and A step of performing random access to a target base station identified by a message triggering the above handover, A handover method in which a message triggering the handover includes SBFD-related information of the target base station.

16. In paragraph 15, A handover method in which random access to the above target base station is performed via the UL sub-band.

17. In paragraph 15, A handover method in which the message that triggers the above handover is an RRCReconfiguration message.

18. In paragraph 15, a step of providing SBFD-related information of the terminal to the source base station; and Further comprising a step of obtaining allocation information of SBFD time domain and UL sub-band from the source base station, The above measurement control report is a handover method transmitted through the UL subband in the above SBFD time domain.

19. In paragraph 15, The step of performing random access to the above target base station is: It includes a step of determining PRACH transmission power for random access to the target base station and a step of performing random access using the determined PRACH transmission power. A handover method in which the PRACH transmission power is determined based on at least one of whether the source base station supports UL repeated transmission in SBFD mode, the number of UL repeated transmissions in SBFD mode for the source base station, whether the target base station supports UL repeated transmission in SBFD mode, and the number of UL repeated transmissions in SBFD mode for the target base station.

20. In paragraph 19, A handover method in which the source base station supports UL repeated transmission in SBFD mode and, when the target base station does not support UL repeated transmission in SBFD mode, the PRACH transmission power is set to be greater than the PRACH transmission power in a legacy system.

21. In paragraph 19, A handover method in which the PRACH transmission power is set to be smaller than the PRACH transmission power in a legacy system when the source base station does not support UL repeated transmission in SBFD mode and the target base station supports UL repeated transmission in SBFD mode.

22. In paragraph 15, A handover method in which the PUSCH transmission power for the target base station is determined based on at least one of whether the source base station supports UL repeated transmission in SBFD mode, the number of UL repeated transmissions in SBFD mode for the source base station, whether the target base station supports UL repeated transmission in SBFD mode, and the number of UL repeated transmissions in SBFD mode for the target base station.

23. In paragraph 22, A handover method in which the source base station supports UL repeated transmission in SBFD mode and the target base station does not support UL repeated transmission in SBFD mode, and the PUSCH transmission power is set to be greater than the PUSCH transmission power in a legacy system.

24. In paragraph 22, A handover method in which the PUSCH transmission power is set to be smaller than the PUSCH transmission power in a legacy system when the source base station does not support UL repeated transmission in SBFD mode and the target base station supports UL repeated transmission in SBFD mode.

25. In paragraph 15, A handover method in which the PUCCH transmission power for the target base station is determined based on at least one of whether the source base station supports UL repeated transmission in SBFD mode, the number of UL repeated transmissions in SBFD mode for the source base station, whether the target base station supports UL repeated transmission in SBFD mode, and the number of UL repeated transmissions in SBFD mode for the target base station.

26. In paragraph 25, A handover method in which the source base station supports UL repeated transmission in SBFD mode and, when the target base station does not support UL repeated transmission in SBFD mode, the PUCCH transmission power is set to be greater than the PUCCH transmission power in a legacy system.

27. In paragraph 25, A handover method in which the PUCCH transmission power is set to be smaller than the PUCCH transmission power in a legacy system when the source base station does not support UL repeated transmission in SBFD mode and the target base station supports UL repeated transmission in SBFD mode.

28. Ministry of Communications; and In a terminal including a processor, The processor performs the steps of: transmitting a measurement control report to a source base station; receiving a message triggering a handover from the source base station; and performing a random access to a target base station identified by the message triggering the handover, wherein the message triggering the handover includes SBFD-related information of the target base station.

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