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WO2022211426A1 - Procédé et appareil de communication entre un réseau non terrestre et un réseau terrestre et terminal dans un système de communication sans fil - Google Patents

Procédé et appareil de communication entre un réseau non terrestre et un réseau terrestre et terminal dans un système de communication sans fil Download PDF

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Publication number
WO2022211426A1
WO2022211426A1 PCT/KR2022/004350 KR2022004350W WO2022211426A1 WO 2022211426 A1 WO2022211426 A1 WO 2022211426A1 KR 2022004350 W KR2022004350 W KR 2022004350W WO 2022211426 A1 WO2022211426 A1 WO 2022211426A1
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Prior art keywords
ntn
cell
handover
terminal
base station
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English (en)
Korean (ko)
Inventor
권기범
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Innovative Technology Lab Co Ltd
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Innovative Technology Lab Co Ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0083—Determination of parameters used for hand-off, e.g. generation or modification of neighbour cell lists
    • H04W36/00837—Determination of triggering parameters for hand-off
    • H04W36/008375—Determination of triggering parameters for hand-off based on historical data
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0055—Transmission or use of information for re-establishing the radio link
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0055—Transmission or use of information for re-establishing the radio link
    • H04W36/0064—Transmission or use of information for re-establishing the radio link of control information between different access points
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0083—Determination of parameters used for hand-off, e.g. generation or modification of neighbour cell lists
    • H04W36/00837—Determination of triggering parameters for hand-off
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0083—Determination of parameters used for hand-off, e.g. generation or modification of neighbour cell lists
    • H04W36/0085—Hand-off measurements
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/08—Reselecting an access point
    • H04W36/087—Reselecting an access point between radio units of access points
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/24—Reselection being triggered by specific parameters
    • H04W36/249—Reselection being triggered by specific parameters according to timing information
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W84/00—Network topologies
    • H04W84/02—Hierarchically pre-organised networks, e.g. paging networks, cellular networks, WLAN [Wireless Local Area Network] or WLL [Wireless Local Loop]
    • H04W84/04—Large scale networks; Deep hierarchical networks
    • H04W84/06—Airborne or Satellite Networks

Definitions

  • the present invention relates to a method and apparatus for communication between a non-terrestrial network and a terrestrial network and a terminal in a wireless communication system.
  • the present invention may provide a method and apparatus for performing communication between a non-terrestrial network and a terrestrial network and a UE based on conditional handover (CHO).
  • ITU International Telecommunication Union
  • IMT International Mobile Telecommunication
  • 5G 5G
  • 3GPP (3rd Generation Partnership Project) NR New Radio
  • TN terrestrial network
  • NTN non-terrestrial networks
  • the present invention may provide a communication method and apparatus for a terminal supporting NTN and TN in a wireless communication system.
  • the present invention relates to a method and apparatus for performing handover of a TN cell in consideration of handover of an NTN cell.
  • the present invention relates to a method and apparatus for processing conditional handover (CHO) information of a TN cell based on handover of the NTN cell.
  • CHO conditional handover
  • the present invention relates to a method and apparatus for setting NTN CHO triggering conditions and TN CHO triggering conditions based on CHO.
  • the present invention may provide a method of operating a terminal supporting NTN and TN in a wireless communication system.
  • the operation method of the terminal may include receiving CHO information for the NTN and TN cell and performing handover of the TN cell in consideration of whether the handover of the NTN cell is proceeding.
  • conditional handover CHO
  • FIG. 1 is a diagram illustrating a wireless communication system to which the present disclosure can be applied.
  • FIG. 2 is a diagram illustrating an NTN including a transparent satellite to which the present disclosure can be applied.
  • FIG. 3 is a diagram illustrating an NTN including a reproduction satellite without an Inter-Satellite Links (ISL) to which the present disclosure can be applied.
  • ISL Inter-Satellite Links
  • FIG. 4 is a diagram illustrating an NTN including a reproduction satellite having an ISL to which the present disclosure can be applied.
  • FIG. 5 is a diagram illustrating a user plane (UP) protocol stack structure in an NTN including a transparent satellite to which the present disclosure can be applied.
  • UP user plane
  • FIG. 6 is a diagram illustrating a control plane (UP) protocol stack structure in an NTN including a transparent satellite to which the present disclosure can be applied.
  • UP control plane
  • FIG. 7 is a diagram illustrating a timing advance calculation method to which the present disclosure can be applied.
  • FIG. 8 is a diagram illustrating an earth fixed cell scenario to which the present disclosure can be applied.
  • FIG. 9 is a diagram illustrating an earth moving cell scenario to which the present disclosure can be applied.
  • FIG. 10 is a diagram illustrating a method of mapping PCI to satellite beams to which the present disclosure can be applied.
  • FIG. 11 is a diagram illustrating a method of operating a feeder link switch for transparent LEO NTN to which the present disclosure can be applied.
  • FIG. 12 is a diagram illustrating a feeder link switching method to which the present disclosure can be applied.
  • FIG. 13 is a diagram illustrating a feeder link switch method for continuous service support to which the present disclosure can be applied.
  • conditional handover (CHO) to which the present disclosure can be applied is performed.
  • 15 is a diagram illustrating a handover preparation step in a CHO procedure to which the present disclosure can be applied.
  • 16 is a diagram illustrating an interoperability scheme of NTN and TN applicable to the present disclosure.
  • 17 is a diagram illustrating an environment in which NTN and TN coexist applicable to the present disclosure.
  • FIG. 18 is a diagram illustrating a method of configuring handover information for NTN and TN to which the present disclosure can be applied.
  • 19 is a diagram illustrating a start time of a handover between NTN cells to which the present disclosure can be applied.
  • 20 is a diagram illustrating a start time of a handover between NTN cells to which the present disclosure can be applied.
  • 21 is a diagram illustrating a handover method to which the present disclosure can be applied.
  • FIG. 22 is a diagram illustrating a handover method to which the present disclosure can be applied.
  • FIG. 23 is a diagram illustrating a grace period for starting a handover procedure between NTN cells to which the present disclosure can be applied.
  • 24 is a diagram illustrating a grace period for starting a handover procedure between NTN cells to which the present disclosure can be applied.
  • 25 is a diagram illustrating a grace period for starting a handover procedure between NTN cells to which the present disclosure can be applied.
  • 26 is a diagram illustrating a method of sharing TN CHO information between an NTN source base station and an NTN target base station to which the present disclosure can be applied.
  • FIG. 27 is a diagram illustrating a CHO triggering configuration to which the present disclosure can be applied.
  • FIG. 28 is a diagram illustrating a CHO triggering configuration to which the present disclosure can be applied.
  • 29 is a diagram illustrating a method of performing a measurement report for handover of a TN cell to which the present disclosure can be applied.
  • FIG. 30 is a diagram illustrating a method of performing a measurement report for handover of a TN cell to which the present disclosure can be applied.
  • FIG. 31 is a diagram illustrating a method of performing a measurement report for handover of a TN cell to which the present disclosure can be applied.
  • FIG. 32 is a diagram illustrating a method of performing a measurement report for handover of a TN cell to which the present disclosure can be applied.
  • FIG 33 is a flowchart illustrating a method of performing handover of a TN cell to which the present disclosure can be applied.
  • 34 is a flowchart illustrating a method of performing handover of a TN cell to which the present disclosure can be applied.
  • 35 is a flowchart illustrating a method of performing handover of a TN cell to which the present disclosure can be applied.
  • 36 is a diagram illustrating the configuration of a base station apparatus and a terminal apparatus to which the present disclosure can be applied.
  • a component when it is said that a component is “connected”, “coupled” or “connected” with another component, it is not only a direct connection relationship, but also an indirect connection relationship in which another component exists in the middle. may also include. Also, when it is said that a component includes “includes” or “has” another component, it means that another component may be further included without excluding other components unless otherwise stated. .
  • first, second, etc. are used only for the purpose of distinguishing one component from other components, and unless otherwise specified, the order or importance of the components is not limited. Accordingly, within the scope of the present disclosure, a first component in one embodiment may be referred to as a second component in another embodiment, and similarly, a second component in one embodiment is referred to as a first component in another embodiment. can also be called
  • components that are distinguished from each other are for clearly explaining each characteristic, and do not necessarily mean that the components are separated. That is, a plurality of components may be integrated to form one hardware or software unit, or one component may be distributed to form a plurality of hardware or software units. Accordingly, even if not specifically mentioned, such integrated or dispersed embodiments are also included in the scope of the present disclosure.
  • components described in various embodiments do not necessarily mean essential components, and some may be optional components. Accordingly, an embodiment composed of a subset of components described in one embodiment is also included in the scope of the present disclosure. In addition, embodiments including other components in addition to components described in various embodiments are also included in the scope of the present disclosure.
  • this specification describes a wireless communication network, and the work performed in the wireless communication network is performed in the process of controlling the network and transmitting data in a system (eg, a base station) having jurisdiction over the wireless communication network, or the corresponding wireless communication network.
  • the operation may be performed in a terminal connected to the network.
  • a 'base station (BS)' may be replaced by terms such as a fixed station, a Node B, an eNodeB (eNB), a gNodeB (gNB), and an access point (AP).
  • eNB eNodeB
  • gNB gNodeB
  • AP access point
  • UE User Equipment
  • MS Mobile Station
  • MSS Mobile Subscriber Station
  • SS Subscriber Station
  • non-AP station can
  • transmitting or receiving a channel includes the meaning of transmitting or receiving information or a signal through a corresponding channel.
  • transmitting the control channel means transmitting control information or a signal through the control channel.
  • transmit a data channel means to transmit data information or a signal over the data channel.
  • NR system is used for the purpose of distinguishing a system to which various examples of the present disclosure are applied from an existing system, but the scope of the present disclosure is not limited by these terms.
  • the NR system supports various subcarrier spacing (SCS) in consideration of various scenarios, service requirements, and potential system compatibility.
  • the NR system has a plurality of channels in order to overcome a poor channel environment such as high path-loss, phase-noise, and frequency offset occurring on a high carrier frequency. It is possible to support transmission of a physical signal/channel through a beam of Through this, the NR system can support applications such as enhanced mobile broadband (eMBB), massive machine type communications (mmTC)/ultra machine type communications (uMTC), and ultra-reliable and low latency communications (URLLC).
  • eMBB enhanced mobile broadband
  • mmTC massive machine type communications
  • uMTC ultra-reliable and low latency communications
  • URLLC ultra-reliable and low latency communications
  • the term NR system is used as an example of a wireless communication system, but the term NR system itself is not limited to the above-described characteristics.
  • 5G mobile communication technology may be defined.
  • the 5G mobile communication technology may be defined to include not only the above-described NR system but also a new version of LTE-Advanced (Long Term Evolution-Advanced) pro system developed together with the NR system. That is, 5G mobile communication may be a technology that operates in consideration of backward compatibility with not only the newly defined NR system but also the previous LTE system.
  • LTE-Advanced Long Term Evolution-Advanced
  • the sidelink field of 5G may include both a sidelink technology in an LTE system and a sidelink technology in an NR system.
  • the sidelink field may be an essential field for performance improvement through ultra-high reliability and ultra-low delay and for grafting new and various services.
  • Figure 1 is a diagram showing a wireless communication system to which the present invention is applied.
  • E-UTRAN Evolved-Universal Terrestrial Radio Access Network
  • NG-RAN Next Generation Radio Access Network
  • E-UMTS Evolved-Universal Mobile Telecommunications System
  • LTE Long Term Evolution
  • LTE-A advanced Term Evolution
  • NR new radio
  • a base station (BS) 11 and a user equipment (UE) 12 may wirelessly transmit and receive data.
  • the wireless communication system 10 may support device-to-device (D2D) communication.
  • D2D device-to-device
  • the concept of a terminal device used by a general user, such as a smart phone, and a terminal device mounted in a vehicle may be included with respect to the above-described terminal.
  • the base station 11 may provide a communication service to a terminal existing within the coverage of the base station through a specific frequency band.
  • the coverage serviced by the base station may also be expressed in terms of a site.
  • a site may include a plurality of areas 15a, 15b, and 15c, which may be referred to as sectors. Each sector included in the site may be identified based on a different identifier. Each of the sectors 15a, 15b, and 15c may be a partial area covered by the base station 11 .
  • the base station 11 generally refers to a station communicating with the terminal 12, eNodeB (evolved-NodeB), gNB (g-NodeB), BTS (Base Transceiver System), access point ( Access Point), femto base station (Femto eNodeB), home base station (HeNodeB: Home eNodeB), relay (relay), remote radio head (RRH: Remote Radio Head), DU (Distributed Unit), such as other terms may be called.
  • eNodeB evolved-NodeB
  • gNB g-NodeB
  • BTS Base Transceiver System
  • Access Point Access Point
  • femto base station Femto eNodeB
  • HeNodeB Home eNodeB
  • relay relay
  • RRH Remote Radio Head
  • DU Distributed Unit
  • the terminal 12 may be fixed or mobile, and may include a mobile station (MS), a mobile terminal (MT), a user terminal (UT), a subscriber station (SS), a wireless device, and a personal digital assistant (PDA). , a wireless modem, a handheld device, and the like.
  • MS mobile station
  • MT mobile terminal
  • UT user terminal
  • SS subscriber station
  • PDA personal digital assistant
  • a wireless modem a handheld device, and the like.
  • the base station 11 may be referred to by various terms such as a megacell, a macrocell, a microcell, a picocell, and a femtocell according to the size of coverage provided by the base station.
  • a cell may be used as a term indicating all or part of a frequency band provided by the base station, coverage of the base station, or base station.
  • downlink refers to a communication or communication path from the base station 11 to the terminal 12
  • uplink is communication from the terminal 12 to the base station 11 or communication path.
  • the transmitter may be a part of the base station 11
  • the receiver may be a part of the terminal 12
  • the transmitter may be a part of the terminal 12
  • the receiver may be a part of the base station 11 .
  • CDMA Code Division Multiple Access
  • TDMA Time Division Multiple Access
  • FDMA Frequency Division Multiple Access
  • OFDMA Orthogonal Frequency Division Multiple Access
  • SC-FDMA Single Carrier-FDMA
  • OFDM-FDMA OFDM-TDMA
  • various multiple access schemes such as OFDM-CDMA
  • a Time Division Duplex (TDD) method transmitted using different times or a Frequency Division Duplex (FDD) method transmitted using different frequencies may be used for uplink transmission and downlink transmission.
  • TDD Time Division Duplex
  • FDD Frequency Division Duplex
  • communication could be performed based on a terrestrial network including a terminal located on the ground and base stations located on the ground.
  • the terminal may access the network via wireless.
  • the terminal can receive the same service continuously through other base stations in the terrestrial network.
  • the terminal could access a specific service server through other wired or Internet networks.
  • the terminal could be provided with a service for connecting wired or wireless communication with another terminal through the network.
  • the NTN may refer to a network or a part of a network using a mobile body floating in the air or space on which a base station or relay equipment is mounted.
  • NTN may support a communication service between terminals based on satellites equipped with communication functions on Low Earth Orbit (LEO) and Geostationary Earth orbit (GEO).
  • LEO Low Earth Orbit
  • GEO Geostationary Earth orbit
  • the NTN may support a communication service between terminals based on an aircraft equipped with a communication function in an unmanned aircraft system (UAS), but is not limited thereto.
  • UAS unmanned aircraft system
  • NTN non-terrestrial networks
  • TN and TN are distinguished and described, and a method of supporting communication service between terminals will be described based on this.
  • a wireless communication service between a terrestrial base station and a wireless terminal or between a mobile base station is described as a mobile service, but is not limited thereto.
  • communication between the mobile terrestrial base stations and at least one or more space base stations may be Mobile Satellite Services.
  • a wireless communication service between mobile terrestrial base stations and space base stations or between mobile terrestrial base stations through at least one or more space base stations may also be a mobile satellite service, but is not limited thereto.
  • NTN network-to-media access technology
  • technologies for NTN have been introduced specifically for satellite communication, but NTN can also be introduced in a communication system (e.g. 5G system) of TN to operate with TN.
  • the terminal may support NTN and TN at the same time.
  • the wireless communication system may require specific technologies for NTN in addition to long-term evolution (LTE) and new radio (NR) systems, which are radio access technology (RAT), for a terminal supporting both NTN and TN.
  • LTE long-term evolution
  • NR new radio
  • RAT radio access technology
  • NTNs Non-terrestrial networks
  • a network or part of a network that uses a mobile body floating in the air or space carrying a base station or relay device for communication.
  • NTN gateway NTN-gateway
  • NTN gateway located on the Earth's surface and equipped with sufficient radio access equipment to access satellites.
  • the NTN gateway may be a transport network layer node (TNL).
  • TNL transport network layer node
  • Geostationary Earth orbit (GEO):
  • the orbiting object or satellite orbits at the same period as the Earth's rotation period. Therefore, when observed from the Earth, it appears to exist in a stationary position with no movement.
  • LEO Low Earth Orbit
  • MEO Medium Earth Orbit
  • UAS Unmanned Aircraft Systems
  • the unmanned aerial system may include at least one of a Tethered UAS (TUA), a Lighter Than Air UAS (LTA), and a Heavier Than Air UAS (HTA) system.
  • TAA Tethered UAS
  • LTA Lighter Than Air UAS
  • HTA Heavier Than Air UAS
  • It may be a wireless communication service between mobile terrestrial base stations and one or more space base stations or between mobile terrestrial base stations and space base stations or between mobile terrestrial base stations via one or more space base stations.
  • Non-Geostationary Satellites
  • Satellites in LEO and MEO orbits may be satellites that orbit the Earth with a period of between about 1.5 hours and 10 hours.
  • It may mean changing the carrier frequency of the uplink RF signal and filtering and amplifying it before transmitting it through the downlink.
  • the uplink RF signal is transformed and amplified before being transmitted through the downlink, and the signal transformation may include digital processing such as decoding, demodulation, re-modulation, re-encoding and filtering.
  • NTN gNB On board NTN gNB:
  • It may refer to an onboard satellite in which a base station (gNB) is implemented in a regenerative payload structure.
  • gNB base station
  • NTN gNB On ground NTN gNB:
  • RTD Round Trip Delay
  • the returned signal may be a signal including a message or a form different from the arbitrary signal.
  • It may be a mobile body in space equipped with a wireless communication transceiver capable of supporting a transparent payload or a replay payload, and may generally be located in LEO, MEO, or GEO orbits.
  • TTT Time to Trigger
  • the measured value of the primary cell (PCell) is less than or equal to the threshold #1 and the measured value of the neighboring cell having another RAT is greater than or equal to the threshold #2
  • PCell Primary Cell
  • PSCell Primary SCG Cell
  • a serving cell performing a random access operation among the serving cells in the SCG during the synchronization RRC reconfiguration procedure (the Reconfiguration with Sync procedure)
  • PCell in MCG or PSCell in SCG, otherwise it may mean PCell.
  • a cell group consisting of serving cells included in the MeNB (Master eNB).
  • the MeNB may include a PCell.
  • the SeNB may not include a PCell.
  • FIG. 2 is a diagram illustrating an NTN including a transparent satellite to which the present disclosure can be applied.
  • the terminal included in the NTN may include the terrestrial network terminal of FIG. 1 .
  • NTN and NT terminals may include a manned or unmanned moving object such as a ship, a train, a bus, or an airplane, and may not be limited to a specific form.
  • a transparent satellite payload generated through a network including transparent satellites may be implemented in a manner corresponding to an RF repeater.
  • a network including a transparent satellite may perform frequency conversion and amplification of a radio signal received in both uplink and downlink directions, and may transmit the radio signal. Accordingly, the satellite can perform a function of relaying the NR-Uu air interface including both the feeder link and the service link in both directions, and the NR-Uu air interface will be described later.
  • a satellite radio interface (SRI) on a feeder link may be included in an NR-Uu interface. That is, the satellite may not be the end of the NR-Uu interface.
  • the NTN gateway may support all functions necessary to transmit signals defined in the NR-Uu interface.
  • other transparent satellites may be connected to the same base station on the ground. That is, a configuration in which a plurality of transparent satellites are connected to one terrestrial base station may also be possible.
  • the base station may be an eNB or a gNB, but may not be limited to a specific form.
  • FIG. 3 is a diagram illustrating an NTN including a reproduction satellite without an Inter-Satellite Links (ISL) to which the present disclosure can be applied.
  • ISL Inter-Satellite Links
  • the NTN may include a reproduction satellite.
  • the reproduction satellite may mean that a base station function is included in the satellite.
  • a reproduction satellite payload generated through a network including a reproduction satellite may be implemented in a manner of regenerating a signal received from the ground.
  • the reproduction satellite may receive a signal from the ground based on the NR-Uu air interface on the service link between the terminal and the satellite.
  • the reproduction satellite may receive a signal from the ground through an SRI on a feeder link between NTN gateways.
  • the SRI Shortlite Radio Interface
  • the transport layer may mean a transport layer among layers defined as OSI 7 layers. That is, a signal from the ground based on the reproduction satellite may be transformed based on digital processing such as decoding, demodulation, re-modulation, re-encoding and filtering, but is not limited thereto.
  • FIG. 4 is a diagram illustrating an NTN including a reproduction satellite having an ISL to which the present disclosure can be applied.
  • the ISL may be defined in the transport layer.
  • the ISL may be defined as a wireless interface or a visible light interface, and is not limited to a specific embodiment.
  • the NTN gateway may support all functions of the transport protocol.
  • each of the regenerative satellites can be a base station, and a plurality of regenerative satellites can be connected to the same 5G core network on the ground.
  • FIG. 5 is a diagram illustrating a user plane (UP) protocol stack structure in an NTN including a transparent satellite to which the present disclosure can be applied.
  • FIG. 6 is a diagram illustrating a control plane (UP) protocol stack structure in an NTN including a transparent satellite to which the present disclosure can be applied.
  • UP user plane
  • UP control plane
  • the NR Uu interface may be an interface defined as protocols for wireless access between a terminal and a base station in an NR system.
  • the NR Uu interface may include a user plane defined by protocols for user data transmission including NTN.
  • the NR Uu interface may include a control plane defined by protocols for transmitting signaling including radio resource control information including NTN.
  • a medium access control (MAC) layer includes a radio link control (RLC), a packet data convergence protocol (PDCP), and a service data adaptation protocol (SDAP).
  • RRC Radio Resource Control
  • the protocol for each layer may be defined based on NR among 3GPP RAN-related standards, but may not be limited thereto.
  • FIG. 5 may be a UP protocol stack structure based on a transparent satellite. That is, in the satellite and NTN gateway, only frequency conversion and amplification of a transparently received radio signal can be performed and transmitted.
  • FIG. 6 may be a CP protocol stack structure based on a transparent satellite. That is, only the frequency conversion and amplification of the transparently received radio signal may be performed in the satellite and the NTN gateway.
  • a wireless communication system supporting communication between terminals using NTN and TN may be considered.
  • the NTN may have a larger roundtrip time (RTT) between the terminal and the base station compared to the existing TN. Therefore, the UE needs to store data to be transmitted through each of the uplink and downlink in the buffer for a longer period of time due to the increase in RTT from the UP viewpoint. That is, the terminal needs to store more data in the buffer. Accordingly, the terminal may require a memory having a larger capacity than before, which will be described later.
  • the signal round trip time may be long.
  • the NTN since the satellites included in the NTN are located in the sky, the signal round trip time (RTT) may be long.
  • RTT signal round trip time
  • FIG. 7 may be a method of calculating a TA value generated according to a satellite payload type.
  • FIG. 7A may be a method of calculating a TA value when the satellite payload type is a reproduction payload.
  • FIG. 7(b) may be a method of calculating a TA value when the satellite payload type is a transparent payload.
  • TA timing advance
  • the terminal knows the satellite ephemeris and the location of the terminal.
  • the satellite orbit may mean a distance between each satellite and a receiver and location information of each satellite.
  • the UE may apply the TA value after acquiring the TA value by itself. (Option 1 below)
  • the UE may receive an instruction for TA compensation and correction from the network. (Option 2 below)
  • the satellite may directly serve as a base station.
  • the UE may calculate a TA value required for uplink transmission including a physical random access channel (PRACH).
  • the UE may calculate a common TA value (Tcom) and a TA value (TUEx) for each UE.
  • Tcom may be a TA value required for all terminals that occur due to a large cell coverage of NTN and a long round trip time (RTT).
  • the NTN is located in the sky and is a relatively longer distance than the distance between terminals
  • a common TA value (Tcom) in consideration of a long round trip time (RTT) in cell coverage may be required.
  • the TA value (TUEx) for each UE may be a value generated due to a different location of each UE within the cell coverage. If the terminal determines the location of the satellite according to a specific time in advance through the satellite ephemeris stored in advance or received from the NTN and knows the location of the corresponding terminal through a function such as GNSS, the terminal will receive the satellite at a specific time. Since the distance between the terminal and the corresponding terminal can be calculated, the TA value can be corrected after acquiring the TA value by itself, and the TA value can be determined through this.
  • the UE may perform uplink timing alignment between UEs received from the base station as full TA compensation.
  • the terminal may perform downlink and uplink frame timing alignment on the network side.
  • the satellite payload type is a transparent payload as shown in FIG. 7(b)
  • the satellite may perform filtering and amplification of a radio signal, and transmit the signal to the NTN gateway. That is, the satellite can act like an RF repeater.
  • the common TA value Tcom may be determined based on the sum of the distance D01 between the reference point and the satellite and the distance D02 between the satellite and the NTN gateway.
  • the feeder link may be changed as the NTN gateway is changed based on the movement of the satellite.
  • the distance between the satellite and the NTN gateway may be changed based on the changed feeder link. Accordingly, the generated common TA value may be changed, and there is a need for updating in the corresponding terminal.
  • an offset is set between the downlink frame timing and the uplink frame timing in the network, it is necessary to additionally consider the case where the TA value generated due to the feeder link is not corrected by the full TA compensation scheme.
  • the UE can only calculate a different TA value (TUEx) for each UE, the UE needs to check one reference point for each beam or cell, and transmits the information to other UEs.
  • TUEx TA value
  • the network needs to manage the offset information regardless of the satellite payload type.
  • the network may provide a value for TA correction to each terminal, and is not limited to the above-described embodiment.
  • a method of instructing TA compensation and correction in the network may be considered.
  • a common TA value may be generated based on common factors for propagation delay shared by all terminals located within the coverage of a satellite beam or cell.
  • the network may transmit a common TA value to UEs for each beam or cell of each satellite based on a broadcast method.
  • the common TA value may be calculated in the network assuming at least one reference position for each beam or cell of each satellite.
  • the TA value (TUEx) for each UE may be determined based on a random access procedure defined in an existing communication system (e.g. Release 15 or Release 16 of an existing NR system).
  • a new field may be required in the random access message.
  • the UE may support TA value correction based on this.
  • FIG. 8 is a diagram illustrating an earth fixed cell scenario to which the present disclosure can be applied.
  • a fixed cell may be a cell in which a position at which a signal is transmitted from a satellite is fixed.
  • the fixed cell can be maintained by changing the antenna and the beam so that the service coverage is fixed at a specific location.
  • satellite 1 810 may maintain a fixed cell while changing antennas and beams during T1 to T3.
  • the specific time T4 elapses, since satellite 1 can no longer service the corresponding location, the service is provided at the corresponding location by satellite 2 820 to maintain service continuity.
  • the beam or cell of satellite 2 820 serving the same location as the location serviced by satellite 1 810 at previous times (T1 to T3) after time T4 is the beam or cell of satellite 1 810.
  • characteristics can be maintained, and the present invention is not limited to the above-described embodiment.
  • a service when a service is provided to satellite 1 810 and satellite 2 820 , at least one or more of a physical cell ID (PCI) value and system information may be maintained the same. That is, as a cell in which service coverage is fixed, it may be generally set based on satellites capable of varying antenna and beam angles among satellites in LEO and MEO orbits except for GEO.
  • PCI physical cell ID
  • FIG. 9 is a diagram illustrating an earth moving cell scenario to which the present disclosure can be applied.
  • a cell in which service coverage moves may be an earth moving cell.
  • each of satellite 1 910 , satellite 2 920 , and satellite 3 930 may provide a service to each cell having a different PCI.
  • the antenna and the beam through which the satellite transmits a signal to the ground are fixed, and a form in which the service coverage moves while the satellite moves according to time may be referred to as an Earth moving cell.
  • the ground mobile cell may be set based on satellites having fixed antenna and beam angles among satellites in LEO and MEO orbits except for GEO.
  • the corresponding satellites may have advantages of lower prices and lower failure rates compared to satellites capable of adjusting the angles of antennas and beams.
  • FIG. 10 is a diagram illustrating a method of mapping PCI to satellite beams to which the present disclosure can be applied.
  • PCI may refer to an index capable of logically distinguishing one cell. That is, beams having the same PCI value may be included in the same cell.
  • PCI may be allocated to several satellite beams.
  • one PCI may be allocated to each satellite beam in one satellite.
  • the satellite beam may consist of one or more SSB beams.
  • One cell (or PCI) may be configured with up to L SSB beams.
  • L may be 4, 8, or 64 depending on the size of the frequency band and/or the subcarrier band, but is not limited to the above-described embodiment.
  • L is similar to the terrestrial network (TN), which is an existing communication system (NR system), one or several SSB indexes may be used for each PCI.
  • TN terrestrial network
  • NR system existing communication system
  • SSBs transmitted through different beams can be distinguished, and the SSB index can be mapped to an antenna port that is logically defined or a beam that is physically separated and formed.
  • a terminal capable of accessing the NTN may be a terminal supporting a Global Navigation Satellite System (GNSS) function.
  • the terminal accessible to the NTN may include a terminal that does not support GNSS.
  • the NTN is a terminal supporting the GNSS function, it may also support a terminal that does not secure location information through the GNSS, and is not limited to the above-described embodiment.
  • a feeder link switch may be required in the NTN based on the movement of the satellite. That is, according to the movement of the satellite, a feeder link (SRI), which is a radio link between a terrestrial NTN gateway and a satellite, for the same satellite may be switched to a feeder link with another NTN gateway.
  • SRI feeder link
  • the feeder link switching may be performed based on at least one of a case of out of coverage of a currently connected NTN gateway according to the movement of a satellite such as maintenance of a feeder link, traffic offloading, or an LEO satellite.
  • the satellite 1110 may establish a feeder link with the NTN gateway 1 1120 based on the base station 1 (gNB 1).
  • the gateway may perform the role of the base station.
  • the present invention is not limited thereto, and it may be possible that the NTN gateway and the base station are configured differently.
  • the feeder link may be switched to the NTN gateway 2 1130 based on the base station 2 (gNB 2 ).
  • the terminal may wish to maintain the service provided even when the feeder link switching is performed.
  • the operation of the feeder link switch may proceed differently depending on the NTN structure type.
  • the following describes based on the transparent payload structure-based feeder link switch operation.
  • the base station may be located on the ground.
  • a user plane and a control plane may be set for each base station. Therefore, in the case of changing from NTN gateway 1 (1120) to NTN gateway 2 (1130) based on feeder link switching, if only one feeder link is set at a time for the satellite to operate, NTN gateway 1 (1120) All terminals receiving a service through the RRC connection may be disconnected at the moment when feeder link switching is started. That is, the RRC connection may be dropped. Thereafter, the satellite 1110 may complete feeder link setup with the NTN gateway 2 1130 . In this case, the UEs whose RRC connection has been disconnected can check the reference signal of the NTN gateway 2 1130 , perform access based on this, and receive the service again.
  • FIG. 12 is a diagram illustrating a feeder link switching method to which the present disclosure can be applied.
  • the satellite 1210 may be connected to the NTN gateway 1 1220 at time T1.
  • the satellite 1210 may establish a plurality of feeder links and may perform connection with a plurality of NTN gateways.
  • the satellite 1210 may be in a state in which it can receive service support through simultaneous connection with the NTN gateway 1 1220 and the NTN gateway 2 1230 .
  • the feeder link switch procedure may be completed in the form of receiving service support only through the NTN gateway 2 1230 at the T2 time point.
  • the feeder link switching of the satellite 1210 may be performed, and based on this, the terminals may be provided with a service without interruption.
  • the aforementioned feeder link switching may be soft feeder link switching (SFLS), and is not limited thereto.
  • the existing system e.g. Switching may be performed similarly to basic operations of the handover procedure of NR Release 15).
  • the different base stations connected to the respective NTN gateways 1220 and 1230 recognize that the terminal is simultaneously performing the service through the transparent satellite and that the service areas overlap. Different radio resources may be used to enable this. That is, the terminal can recognize each of the different base stations separately at the same time.
  • the base station connected to the NTN gateway 2 1230 may transmit cell defining synchronization signaling blocks (CD-SSBs) in a cell included in the corresponding base station.
  • CD-SSBs may have a synchronization raster point different from that of cells in the base station connected to the NTN gateway 1 1220 .
  • the UE may handover to a cell having a physical cell ID (PCI) value of a cell belonging to a base station connected to NTN gateway 1 1220 and another PCI value belonging to a base station connected to NTN gateway 2 1230 .
  • the handover may be performed in the form of a blind handover performed by the network without measurement.
  • the handover may be performed in a manner that additionally considers the orbital force of the satellite and the location information of the terminal based on the RSRP (Reference Signal Received Power)/RSRQ (Reference Signal Received Quality) measurement information of the terminal.
  • RSRP Reference Signal Received Power
  • RSRQ Reference Signal Received Quality
  • the NTN gateway 1 1220 may configure a conditional handover (CHO) in advance to the NTN gateway 2 1230 for the UE at the time T1.
  • CHO conditional handover
  • the terminal may directly proceed with the handover based on the preconfigured CHO configuration information.
  • the service link with the same satellite may not be changed based on the above-described handover. Therefore, since the terminal performs radio link performance measurement based on the reference signal, it is necessary to consider an approach different from that of the TN because the handover to different base stations has very similar RSRP/RSRQ measurement values for each. .
  • the feeder link switching may be performed by the satellite 1310 stopping the signaling transmission received from the NTN gateway 1 1320 at the time T1 and performing the signaling transmission received from the NTN gateway 2 1330 at the time T2.
  • the above-described feeder link switching may be hard feeder link switching (HFLS), and is not limited to the above-described name.
  • the satellite 1310 may be connected to only one feeder link during a feeder link switching procedure.
  • the satellite 1310 cannot be connected through a plurality of feeder links, only one of the NTN gateway 1 ( 1320 ) and the NTN gateway 2 ( 1330 ) can perform the connection.
  • the UE may not be able to transmit/receive signaling of a serving cell in any base station during the time period T1 to T2. Therefore, the terminal needs to perform a procedure for reconnecting with the serving cell.
  • the UE may be provided with handover indication information in advance before time T1, and may perform handover at time T2 based on the CHO scheme. That is, the handover indication information for CHO may include information on time T2, and may indicate that the handover procedure starts after time T2.
  • the terminal may receive service support through the existing feeder link until T1, and then start the service through the new feeder link from the time T2. That is, service may be resumed immediately at the time T2, which is a time point at which service can be resumed through a new feeder link.
  • the above-described information may be equally provided to all terminals serving through the existing feeder link.
  • the UE may perform the HFLS procedure based on the conditional RRC reconfiguration procedure.
  • the NTN cell size may be very large compared to the TN. Accordingly, the number of users in the NTN cell may be greater than the number of users in the TN cell.
  • there may be a limitation in providing all handover information to each terminal within a short time For example, it may not be possible to provide handover indication information to some UEs before the T1 time point. Due to this, the UE experiences a radio link failure (RLF) situation and may start the RRC reconfiguration procedure as a follow-up measure.
  • RLF radio link failure
  • the UE operates in consideration of the period for RLF determination that must be performed before entering the RRC reconfiguration procedure, the cell reselection procedure required during the RRC reconfiguration procedure, and the RRC reconfiguration procedure failure even if the time required for the RRC reconfiguration procedure is excluded. and delay may occur based on this.
  • the NTN may provide a system information block (SIB) including feeder link switching related information to all terminals in the cell in a broadcast manner.
  • the SIB may include feeder link switching related information.
  • the SIB may include information such as a next cell ID value through which the UE can omit the cell reselection procedure instead of the RRC reconfiguration procedure, and an additional RRC reconfiguration procedure start condition for omitting the RLF determination period.
  • the UE may reduce the signaling load required for the feeder link switch procedure that continuously occurs based on the received information.
  • conditional handover (CHO) to which the present disclosure can be applied is performed.
  • the CHO may be a handover executed by the UE when at least one or more handover execution conditions are satisfied.
  • the UE may receive CHO configuration information in advance.
  • the UE may check whether execution conditions for CHO are satisfied. In this case, when the UE performs handover based on the existing handover or CHO, the UE may stop evaluating the handover condition.
  • the CHO configuration information may include configuration information generated by at least one or more CHO candidate cells and information on at least one or more execution conditions generated by the source base station.
  • the execution condition may consist of one or two triggering conditions, but is not limited thereto.
  • the above-described A3 and A5 may be configured as CHO events.
  • the UE may perform a measurement operation and report to check whether the above-described event condition is satisfied.
  • the UE may evaluate the CHO execution condition of each candidate cell through the same measurement criterion.
  • the UE supports only one RS (reference signal) type at the same time and can support up to two different trigger values.
  • the UE may set a trigger value for the CHO execution condition for RSRP and RSRQ based on the same type of RS.
  • the UE may set a trigger value for a CHO execution condition in which RSRP and signal interference noise ratio (SINR) are based on the same type of RS.
  • SINR signal interference noise ratio
  • the UE may perform handover by determining that the CHO execution condition is satisfied only when both set trigger values are satisfied.
  • the UE may not consider the previously received CHO configuration. That is, the UE may perform a general handover procedure according to the received handover indication information and may not determine whether the CHO execution condition is satisfied. Also, as an example, when the UE performs handover based on CHO, the UE may not monitor the source cell from the time when synchronization with the target cell starts.
  • a handover procedure in the control plane of the terminal may be considered.
  • the 5G core network (5GC) may not be involved in signaling generation and operation in the terminal and the base station in the stage of preparation and execution of the NR RAN CHO, which is performed as a handover within the NR RAN. That is, handover preparation messages may be exchanged between base stations. Accordingly, the target base station may trigger resource release of the source base station in the CHO completion phase.
  • FIG. 14 is a diagram illustrating a CHO procedure without changing an access and mobility management function (AMF) and a user plane function (UPF). More specifically, referring to FIG. 14 , the terminal 1410 may receive data from the source base station 1420 based on the UPF 1460 . Here, the source base station 1420 and the target base station 1430 may receive mobility control information from the AMF 1450 . Also, the terminal 1410 may perform measurement based on RS and report measurement information to the source base station 1420 . In this case, the source base station 1420 may determine whether a CHO execution condition is satisfied, and may determine handover if the CHO execution condition is satisfied.
  • AMF access and mobility management function
  • UPF user plane function
  • the source base station 1420 may transmit a handover request to the target base station 1430 and the target candidate base station 1440 .
  • Each of the target base station 1430 and the target candidate base station 1440 may check each handover request based on admission control. Thereafter, the source base station 1420 may provide RRC reconfiguration information to the terminal 1410 , and the terminal may handover to the target base station 1430 by completing the RRC reconfiguration.
  • the terminal since both the source base station 1420 and the target base station 1430 may be supported by the AMF, the terminal may perform CHO without changing the AMF and the UPF.
  • FIG. 15 is a diagram illustrating a handover preparation step in a CHO procedure to which the present disclosure can be applied.
  • the terminal 1510 may evaluate the CHO execution condition. That is, the terminal 1510 may determine whether the CHO execution condition is satisfied. Thereafter, the terminal 1510 may perform synchronization with the selected target base station 1530 after disconnection from the existing base station (source base station, 1520 ). Thereafter, the terminal may complete the handover based on the CHO with the target base station 1530 . Thereafter, the target base station 1530 may provide information on whether handover is successful to the source base station 1520 and receive sequence number (SN) status information for data operated in the PDCP layer.
  • SN sequence number
  • the source base station 1520 may transmit handover cancellation information to the target base station 1530 and the target candidate base stations 1540 .
  • the source base station 1520 may transmit a handover request to the target base station 1530 and the target candidate base station 1540 based on the CHO. Therefore, when the terminal completes handover to a specific cell of the target base station 1530, the source base station 1520 needs to deliver handover cancellation information to the remaining target candidate base stations 1540 and other cells of the target base station 1530. have.
  • the procedure for the case in which the source base station 1520 transmits the handover cancellation information is not transmitted to the target base station 1530 via the source base station 1520, but user data is directly transferred from the UPF 1560 to the target base station through the terminal. It may include a path switch procedure to be transmitted to , and is not limited to the above-described embodiment.
  • the terminal information (UE context) in the source base station may include information on roaming and access restrictions provided during a recent tracking area (TA) update or RRC connection establishment. That is, the source base station may check an accessible base station and a radio access network for the corresponding terminal based on the corresponding information. The source base station may configure a measurement procedure for radio performance to the terminal, and the terminal may report the measurement result to the source base station according to the measurement procedure. Thereafter, as described above, the source base station may check whether the CHO execution condition is satisfied based on the UE's measurement report, and may proceed with the handover procedure based on the CHO.
  • TA tracking area
  • the source base station may request a CHO from one or a plurality of candidate base stations to which at least one cell selected based on the UE's measurement report value belongs.
  • the target base station may perform an admission control operation based on the received CHO request. For example, when slice information including information on a specific service is included in the CHO request, the target base station may always consider whether slice support is possible. For example, when the target base station cannot select an AMF supporting a slice capable of supporting the specific service, the target base station may have to reject the request.
  • the target candidate base station that has accepted the CHO request through the admission control operation may include the configuration information of the CHO candidate cell in the CHO response message (e.g.
  • the target base station may generate a CHO response message for each candidate cell and transmit it to the source base station.
  • the source base station may transmit an RRC Reconfiguration message including configuration information for CHO candidate cells and CHO execution conditions to the terminal.
  • the UE may transmit an RRC ReconfigurationComplete message to the source base station.
  • the UE may start evaluating CHO execution conditions for candidate cells while maintaining the connection with the source base station through the received CHO configuration information.
  • the UE disconnects from the source eNB and applies the configuration information for the selected candidate cell stored in the UE, and then Synchronization with the candidate cell may be performed. Thereafter, the UE may complete the RRC handover procedure by transmitting an RRC ReconfigurationComplete message to the target base station. Thereafter, the UE may release the stored CHO configuration information after the successful completion of the RRC handover procedure.
  • the target base station may transmit a HANDOVER SUCCESS message to the source base station to inform information that the terminal has successfully accessed the target cell.
  • the source base station may transmit an SN status transfer message including information on a PDCP sequence number (SN) reception status for uplink and information on a downlink PDCP SN transmission status.
  • the source base station may transmit a HANDOVER CANCEL message to all base stations including a cell other than the target cell in order to cancel the CHO that the terminal will not proceed, and the handover procedure is completed based on the above.
  • NTN and TN are a diagram illustrating an interoperability scheme of NTN and TN applicable to the present disclosure.
  • both services may be supported by NTN and TN in a communication system (e.g. 5G system).
  • a communication system e.g. 5G system
  • service continuity may be provided when the TN and the NTN are owned by the same telecommunication operator.
  • service continuity may be provided when TN and NTN are different telecommunication operators, but can be moved based on the agreement of the owner.
  • NTN and TN may be operated in different frequency bands (e.g. FR1/FR2).
  • NTN and TN may be operated in the same frequency band (e.g.
  • FIG. 16 may be a communication system in which NTN and TN are mixed, and the terminal may be provided with service continuity based on NTN and TN.
  • the TN since the TN may be a terrestrial network, the RTT may be smaller than that of the NTN located in the sky. Accordingly, power consumption of the terminal may be relatively low.
  • uplink power consumption may be greater for an NTN located at a long distance.
  • the location information of the terminal through the GNSS may not necessarily be necessary.
  • power consumption required in a data transmission/reception situation may be low.
  • additional procedures such as handover may not be required.
  • the network service area is limited to the vicinity of the base station (e.g., within 1km in the case of an urban area), the service may not be provided in the area where the base station is not installed.
  • the coverage of the base station may be smaller, so there may be a limit in service provision.
  • a performance difference between an area adjacent to a base station and an area outside the base station may be large. For example, when the terminal is located at the edge of the cell, performance degradation may occur.
  • NTN can be applied against the pros and cons of TN.
  • the serviceable area of one satellite may be very wide from a minimum of 20 km (e.g. LEO) to a maximum of 1200 km (e.g. GEO). Therefore, it may not be necessary to install many base stations.
  • LEO low-latency evolution
  • GEO maximum-latency evolution
  • the RTT may be large (e.g. about 541 ms in the case of GEO).
  • the distance between the satellite and the terminal may be considerably larger than that of the TN, power consumption may be high (e.g. satellite and the terminal).
  • a terminal supporting both TN and NTN in a communication system can support a service by the TN.
  • the terminal may be advantageous for the terminal to set one of the cells in the NTN as a serving cell to receive the service.
  • the terminal may be able to access the TN when passing through an area adjacent to land.
  • the terminal may not be able to access the TN, and since it may be highly likely that the terminal will immediately exit to an area where only NTN is supported, it may be advantageous to continuously access the NTN.
  • the NTN may check the approximate location information of the terminal through the measurement report of the terminal for the NTN and the TN. Also, as an example, the NTN may receive additional information for checking the physical location information of the terminal, such as a location service, from a location information service related server.
  • FIG. 17 is a diagram illustrating an environment in which NTN and TN coexist applicable to the present disclosure.
  • a UE may set a preferred network in case of possible handover according to movement of the UE.
  • UE 1 UE 1, 1710
  • UE 1 may move in an overlapping environment of NTN and TN.
  • a preferred network for handover may not be set in the terminal 1 1710 .
  • UE 2 (UE 2, 1720) may be in an environment in which NTN and NT overlap at the current location, but handover to TN according to movement may be advantageous for service provision. Accordingly, the TN may be configured as a preferred handover in the terminal 2 1720 , and a method for performing a handover will be described in consideration of the above-described circumstances.
  • the items described below are handover based on CHO to support service continuity based on a mobile cell based on one NTN LEO satellite as a boundary of a TN cell in a wireless communication system in which NTN and TN are mixed.
  • the above-described situation is only a situation for convenience of description, and in a wireless communication system in which NTN and TN are mixed, the matters described below may be applied in another form.
  • the following description is only based on the above-described situation for convenience of description, but is not limited thereto.
  • the terminal 1820 may be a terminal in which both the NTN and the TN in FIG. 17 are capable of handover.
  • the terminal 1820 may receive CHO information from the source base station 1810 . Also, the terminal 1820 may obtain NTN and TN handover related information from the source base station 1810 through RRC signaling. That is, the terminal 1820 may configure handover information for NTN and TN in advance based on the CHO instruction. In this case, execution conditions for handover may be set in the terminal 1820 . When the corresponding execution condition is satisfied, the terminal 1820 may perform handover. Here, the terminal 1820 may proceed with the measurement of the TN cell. As described above, the terminal 1820 may perform measurement based on a plurality of triggering conditions based on one RS type. When the CHO execution condition for the TN is satisfied, the UE may handover to a cell included in the TN.
  • a triggering timer in which CHO is triggered based on the execution condition may be started.
  • the triggering timer may be a timer for checking a time period in which a situation in which a specific criterion for an event set as a handover execution condition is satisfied is maintained. That is, the UE may perform a time to trigger (TTT) for handover triggering based on a time period determined by a timer or a parameter value.
  • TTTT time to trigger
  • a case where the source base station 1810 is an NTN source base station may be considered.
  • the service link or feeder link for the satellite may be changed based on the movement of the satellite.
  • handover may be performed from the NTN source base station 1810 to the NTN target base station 1830 after a predetermined time elapses based on the movement of the satellite. That is, the service link or feeder link of the NTN source base station 1810 may be changed based on the movement of the satellite (e.g. LEO). Therefore, although TTT is being performed to trigger handover from the terminal 1820 to the TN cell, handover between NTN cells may be started due to movement of the satellite.
  • the satellite e.g. LEO
  • the TTT in progress in the terminal 1820 may be stopped when the handover between NTN cells starts. That is, the triggering timer may be stopped. Thereafter, a handover between NTN cells may be performed to change a service link or a feeder link to the NTN target base station 1830 .
  • a handover between NTN cells may be performed to change a service link or a feeder link to the NTN target base station 1830 .
  • CHO information for a TN cell is maintained in the terminal after a service link or a feeder link is changed by handover to the NTN target base station 1830 may be considered.
  • the handover to the TN cell may be performed based on the mobility of the UE, but the handover of the NTN cell may be performed based on a predetermined time based on the movement of the satellite.
  • the terminal 1820 may complete the handover procedure for the target NTN cell and restart the interrupted TTT.
  • the UE 1820 may perform measurement on a TN cell and restart TTT.
  • the TTT may be newly restarted. Thereafter, the terminal 1820 may handover to the TN cell based on the TN base station 1840 when the triggering timer expires.
  • the CHO condition of the existing NTN source base station 1810 and the CHO condition of the handed over NTN target base station 1830 may be different.
  • a satellite may be changed or a cell type may be changed.
  • the CHO information for the TN cell configured in the UE needs to be changed, which will be described later.
  • the start time of the handover between NTN cells may be variously determined. More specifically, as described above, a handover to a TN cell may be performed based on the CHO information, and a triggering timer may be started. In addition, handover to an NTN cell may also proceed based on location, time, or other triggering conditions. Here, a handover start time between NTN cells may be variously determined.
  • FIGS. 19 and 20 are diagrams illustrating a start time of a handover between NTN cells to which the present disclosure can be applied.
  • an NTN candidate cell determination period may be configured.
  • the start time (T2) of the NTN candidate cell determination period may be a start time when the RSRP/RSRQ value measured by the UE exceeds the threshold value.
  • the terminal may be a time point determined to be the same as the time point information based on the time information provided based on the time used in Universal Time Coordinated (UTC) or NTN among the CHO conditions provided by the base station.
  • UTC Universal Time Coordinated
  • the start time of the handover between NTN cells may be determined as T2, which is the start time of the NTN candidate cell determination period. That is, when TTT is performed in the terminal, it is determined that the handover between NTN cells has started at the start time (T2) of the NTN candidate cell determination period, and the TTT process can be stopped.
  • the start time of the NTN handover may be the NTN candidate cell handover determination time (T3).
  • the NTN candidate cell handover decision time (T3) is a value in which the RSRP/RSRQ value measured by the UE exceeds the threshold in the A3 to A5 event configuration information set for the corresponding NTN candidate cell #1 for a certain period of time (e.g. TTT) or more It may be a time point that satisfies the event occurrence condition by being satisfied. That is, the start time of the handover between NTN cells may be the determination time (T3) for the actual handover of the NTN candidate cell. Therefore, when TTT is performed in the UE, it is determined that the handover between NTN cells has started at the NTN candidate cell handover decision time (T3), and the TTT process can be stopped.
  • the UE does not stop the TTT for the TN, and may continue to perform the TTT for the TN before starting the NTN inter-cell handover procedure.
  • 21 is a diagram illustrating a handover method to which the present disclosure can be applied.
  • the terminal 2120 may receive CHO information from the source base station 2110 .
  • the terminal 2120 may obtain NTN and TN handover related information from the source base station 2110 through RRC signaling. That is, the terminal 2120 may configure handover information for NTN and TN in advance based on the CHO instruction.
  • an execution condition for handover may be set in the terminal 2120 . When the corresponding execution condition is satisfied, the terminal 2120 may perform handover.
  • the terminal 2120 may proceed with the measurement of the TN cell. As described above, the terminal 2120 may perform measurement based on a plurality of triggering conditions based on one RS type.
  • the UE may handover to a cell included in the TN.
  • a triggering timer or time period in which the CHO is triggered based on the execution condition may be started.
  • the triggering timer may be a timer for checking a time period in which a situation in which a specific criterion for an event set as a handover execution condition is satisfied is maintained.
  • the terminal proceeds with a time to trigger (TTT) for handover triggering based on the timer or sets a time period based on the triggering time and performs triggering when the triggering maintenance condition is satisfied during the corresponding time period.
  • TTT time to trigger
  • the source base station 2110 is an NTN source base station
  • the service link or feeder link for the satellite may be changed based on the movement of the satellite.
  • handover may be performed from the NTN source base station 2110 to the NTN target base station 1830 after a predetermined time elapses based on the movement of the satellite. That is, the service link or feeder link of the NTN source base station 2110 may be changed based on the movement of the satellite (e.g. LEO). Therefore, although TTT is being performed to trigger handover from the terminal 1820 to the TN cell, handover between NTN cells may be started due to movement of the satellite.
  • the UE may proceed with a handover procedure to the TN. That is, the triggering timer may not be stopped.
  • the case where the NTN handover start time is the NTN candidate cell determination period start time (T2) may be considered.
  • the UE determines that the priority for the TN cell is higher than that of the NTN cell, and performs the handover procedure for the TN.
  • the number of services that can be supported through the TN cell may be greater, and the delay time of the TN cell may be relatively lower than that of the NTN cell.
  • the UE may determine that the priority for the TN cell is higher than that of the NTN cell, and may perform handover to the TN cell without stopping the TTT process.
  • the start of the NTN inter-cell handover procedure may be deferred for a predetermined period even if the start condition of the NTN inter-cell handover procedure is satisfied.
  • the terminal may continue to perform TTT for the TN.
  • the UE may proceed with the handover procedure for the TN.
  • a case in which the grace period for starting the NTN inter-cell handover procedure expires before determining the handover for the TN may be considered. That is, when the TTT for the TN is predicted to end after the grace period for starting the NTN inter-cell handover procedure expires, the NTN inter-cell handover may be performed immediately at the time of determining the NTN inter-cell handover.
  • a handover procedure between NTN cells may be performed at the time when the TTT is stopped.
  • FIG. 22 is a diagram illustrating a handover method to which the present disclosure can be applied.
  • the terminal 2220 may receive CHO information from the source base station 2210 .
  • the terminal 2220 may obtain NTN and TN handover related information from the source base station 2210 through RRC signaling. That is, the terminal 2220 may configure handover information for NTN and TN in advance based on the CHO instruction.
  • execution conditions for handover may be set in the terminal 2220 .
  • the terminal 2220 may perform handover.
  • the terminal 2220 may proceed with the measurement of the TN cell.
  • the terminal 2220 may perform measurement based on a plurality of triggering conditions for only one RS type.
  • the UE may handover to a cell included in the TN.
  • a triggering timer or time period in which the CHO is triggered based on the execution condition may be started.
  • the triggering timer may be a timer for checking a time period in which a situation in which a specific criterion for an event set as a handover execution condition is satisfied is maintained.
  • the terminal proceeds with a time to trigger (TTT) for handover triggering based on the timer or sets a time period based on the triggering time and performs triggering when the triggering maintenance condition is satisfied during the corresponding time period.
  • TTT time to trigger
  • the source base station 2210 is an NTN source base station
  • the service link or feeder link for the satellite may be changed based on the movement of the satellite.
  • handover may proceed from the NTN source base station 2210 to the NTN target base station 1830 . That is, the service link or feeder link of the NTN source base station 2210 may be changed based on the movement of the satellite (e.g.
  • the terminal 2220 may perform a handover procedure to the TN. That is, the triggering timer may not be stopped.
  • the case where the NTN handover start time is the NTN candidate cell determination period start time (T2) may be considered. At this time, when the handover for the TN is determined and the handover for the NTN is also determined, the terminal 2220 may continue the TTT without stopping the TTT progress of the TN cell.
  • the start of the handover procedure between NTN cells may be delayed for a certain period of time. For example, if handover to the TN is determined within the grace period for starting a handover procedure between NTN cells, the terminal 2220 may perform a handover procedure for the TN.
  • a case in which the grace period for starting the NTN inter-cell handover procedure expires before determining the handover for the TN may be considered. That is, when the TTT for the TN is predicted to end after the grace period for starting the NTN inter-cell handover procedure expires, the NTN inter-cell handover may be performed immediately at the time of determining the NTN inter-cell handover. As another example, if the TTT is stopped by satisfying the leaving condition before the expiration of the TTT for the TN, a handover procedure between NTN cells may be performed at the time when the TTT is stopped.
  • the threshold for the leaving condition may be set separately from the threshold for the CHO triggering condition.
  • FIGS. 23 to 25 are diagrams illustrating a grace period for starting a handover procedure between NTN cells to which the present disclosure can be applied.
  • the length L3 configured from the network in FIGS. 23 and 24 may be set and operated.
  • it may be defined from a time point T3 for determining a handover between NTN cells to a time point for ending a time point for determining a handover between NTN cells (T4).
  • T3 for determining a handover between NTN cells
  • T4 time point for ending a time point for determining a handover between NTN cells
  • the NTN candidate cell #1 it may not be a problem even if the handover between NTN cells is started at any time from the start time (T2) to the end time (T4) of the determination period. Therefore, since detailed parameter setting for the handover procedure start grace period setting is not required, only an on/off type indicator indicating whether or not to set the handover procedure start grace period between NTN cells may be transmitted.
  • a case in which CHO condition information for the TN is not configured in the UE and transmitted including only an on/off type indicator indicating only whether to set up a grace period for starting a handover procedure between NTN cells is considered.
  • the UE can receive the RRC reconfiguration message including the handover command for the TN after transmitting the measurement report to the NTN, such as A3/A5 or B1/B2 for the TN, even in this case, the NTN inter-cell hand
  • the over procedure start grace period is activated.
  • the terminal determines that the NTN configures the CHO for the TN to the corresponding terminal as setting the handover priority for the TN high, and the terminal indirectly configures the NTN inter-NTN inter-cell handover procedure start grace period setting.
  • the NTN inter-NTN inter-cell handover procedure start grace period setting can be recognized as directed.
  • providing the CHO for the TN in advance means that even if the NTN cell moves to an area where it is difficult to provide handover indication information according to the movement of the UE, the It may be necessary to proceed with a handover.
  • condition for determining the operation to proceed with the handover between NTN cells immediately at the time of determining the handover between the NTN cells may be a case in which the TTT for the TN is expected to end after the time T4 as shown in FIG. Examples are not limited.
  • candidate cell information for TN CHO may be shared during handover between NTN cells. More specifically, NTN may have many users within a cell.
  • the CHO for the TN cell may be performed based on the mobility of the UE. Therefore, when handover between NTN cells is performed in a state in which the UE does not move, it is necessary to maintain the existing CHO information. That is, if all CHO information is newly set every time an NTN inter-cell handover procedure is performed, a signaling load may be large, and it is necessary to maintain unaltered and continuously valid information among CHO information without being released.
  • information provided through the CHO may not be released even when the handover procedure is completed.
  • the information on TN cells as information provided through the CHO is an independent environment independent of the progress of handover between NTN cells, maintaining the information can reduce the signaling load.
  • a case where there is no mobility of the terminal or a case where it is lower than a preset value may be considered.
  • the TN cell since the TN cell may be changed based on the mobility of the terminal, it is necessary to maintain information on the TN cells if the mobility of the terminal is absent or is lower than a preset value. That is, the information on the TN cells may be information on an independent environment based on the mobility of the UE regardless of the case in which handover between NTN cells is performed. Accordingly, information on the TN cell as information provided through the CHO may be maintained until the situation between the UE and the TN is changed through the UE's measurement information report.
  • information on the TN cell as information provided through the CHO may be maintained until the NTN recognizes it by transmitting a message indicating that it is difficult to maintain the CHO in the TN candidate cell.
  • information on a TN cell as information provided through a CHO is maintained in a CHO in a TN candidate cell, addition or removal of CHO candidate cells for the TN may not proceed.
  • the source base station may transmit a handover cancellation message to the base station including the NTN target cell and all base stations including other cells as the handover is completed. For example, when all information of NTN and TN CHO candidate cells in the terminal is removed through NTN inter-cell handover, the NTN target base station sends a handover request message for CHO to the same TN candidate cells according to the measurement report received from the terminal. A procedure of transmitting and receiving information for the same CHO handover from the TN cell may proceed. That is, the procedure may be repeated to obtain CHO information for the same TN cell based on the handover between NTN cells.
  • the NTN source base station may share information on the TN CHO candidate cells with the NTN target base station.
  • the NTN target base station may transmit information that it is the base station including the cell handed over by the corresponding terminal in the NTN to the base stations including the candidate cell in the TN.
  • the NTN target base station can check whether CHO information set in the existing NTN source base station as a candidate cell in the TN is valid, thereby omitting unnecessary procedures.
  • the NTN source base station 2610 may share CHO information for the TN with the NTN target base station 2630 .
  • the NTN source base station 2610 may provide CHO information to the terminal 2620 .
  • the NTN source base station 2610 may provide TN and NTN cell handover information to the terminal 2620 through RRC signaling.
  • the NTN source base station 2630 may know the location information of the terminal to configure a candidate cell for NTN CHO. Thereafter, handover to the NTN target cell may proceed based on the NTN target base station 2630 .
  • the NTN target base station 2630 may deliver measurement control and report configuration information to the terminal 2620 through RRC signaling.
  • the NTN target base station 2630 may transmit the NTN handover result to the TN base station 2640 .
  • the NTN target base station 2630 may transmit an NTN handover result report to the TN base station 2640 when the NTN target base station determines that the handover with the terminal is complete. That is, the NTN target base station 2630 may transmit the NTN handover result report to the TN base station 2640 before or at the same point in time before transmitting the handover completion message to the terminal 2620 , and is not limited to the above-described embodiment.
  • the NTN target base station 2630 may provide information about the change of the NTN base station from the NTN source base station 2610 to the NTN target base station 2630 based on the NTN handover result report.
  • the NTN target base station 2630 may check whether CHO information for a TN candidate cell is changed based on the NTN handover result report. Thereafter, the NTN target base station 2630 may receive TN CHO change confirmation information from the TN base station 2640 . That is, the TN base station 2640 may check whether the TN CHO has changed based on the NTN handover result report, and transmit the information to the NTN target base station 2630 . Thereafter, the NTN target base station 2630 may deliver CHO information to the terminal. Also, as an example, the NTN target base station 2630 may deliver TN and NTN cell handover information through RRC signaling.
  • the NTN target base station 2630 receives CHO information for the TN base station 2640. It can be judged that it is no longer valid. At this time, the NTN target base station 2630 deletes CHO information for the corresponding TN base station 2640 and transmits it through RRC signaling.
  • the terminal 2620 may check the TN candidate cell list in the CHO information received from the NTN target base station 2630 .
  • the UE may not report measurement for CHO for cells included in the TN candidate cell list.
  • the UE may perform a measurement report on a TN candidate cell to be excluded from the TN candidate cell list.
  • the NTN target base station 2630 may set a measurement report to the terminal 2620 , and the terminal may perform a measurement report for excluding from the list based on the configured measurement report.
  • the NTN target base station 2630 may provide the UE 2620 with an A2 event-based measurement report configuration in an RRC reconfiguration message including CHO information for TN and NTN cells.
  • the A2 event may be an event triggered when the neighboring cell has a value less than or equal to a threshold. Therefore, when there is a TN candidate cell that is measured and reported based on the A2 event, the NTN target base station 2630 transmits an RRC reconfiguration message including information for excluding the TN candidate cell from the CHO candidate cell to the corresponding terminal 2620 .
  • the UE 2620 may perform a measurement report for excluding a CHO candidate cell based on the received information.
  • the NTN base station may use the RRC reconfiguration message to transmit CHO information for the TN and NTN cells to the UE.
  • the RRC reconfiguration message may include a ConditionalReconfiguration message including CHO information.
  • the condition reconfiguration message may include information on the CHO configuration that is newly added or whose contents are changed.
  • the UE may check CHO information for TN and NTN cells based on the conditional reconfiguration message included in the RRC reconfiguration message.
  • FIG. 27 is a diagram illustrating a conditional reconfiguration message to which the present disclosure can be applied.
  • the condition reconfiguration message may include a condition reconfiguration addition/change list.
  • the condition reconfiguration addition/change list may include each CHO configuration.
  • Each CHO configuration may include at least one of an ID indicating the corresponding configuration, an execution condition, and reconfiguration information to be applied during execution.
  • the execution condition may be generated by the corresponding source base station.
  • reconfiguration information to be applied when executing CHO may be composed of information provided by each candidate target base station.
  • the conditional reconfiguration addition/change list may include up to 8 CHO configurations based on the addition or change.
  • the execution condition may include up to two CHO triggering configurations.
  • each measurement ID may be set as the execution condition.
  • the measurement target may be the same for all measurement IDs within a single execution condition. That is, a measurement target for CHO may be limited to a single candidate target cell.
  • the CHO triggering configuration may be set as one of the report types of the existing measurement report configuration. For example, when CHO triggering is configured, the UE may perform a handover execution procedure to the corresponding candidate target cell according to the CHO execution procedure without reporting to the base station when the triggering condition is satisfied.
  • the UE may receive an RRC reconfiguration message including a conditional reconfiguration message for CHO from the NTN base station.
  • the UE may distinguish and manage the TN candidate cell and the NTN candidate cell for CHO candidate cell (hereinafter, candidate cell) information that can be provided through the conditional reconfiguration message.
  • the base station may use the RRC reconfiguration message to send CHO information for the TN and/or NTN to the terminal.
  • the conditional reconfiguration message including CHO information may be included in the RRC reconfiguration message.
  • information on a CHO configuration that is newly added or whose contents are changed may be included, as described above.
  • each CHO configuration may include at least one of an ID indicating the corresponding configuration, an execution condition, and reconfiguration information to be applied during execution.
  • the execution condition may be generated by the corresponding source base station.
  • reconfiguration information to be applied when executing CHO may be composed of information provided by each candidate target base station.
  • the conditional reconfiguration addition/change list may include up to 8 CHO configurations based on the addition or change, as described above.
  • up to 8 CHO configurations may be configured for each TN or NTN through addition or change.
  • up to 8 CHO configurations may be configured for both TN and NTN through addition or change, and is not limited to the above-described embodiment.
  • the execution condition may have a maximum of two CHO triggering configurations for a TN candidate target cell and a maximum of three or four CHO triggering configurations for an NTN candidate target cell, but is not limited thereto.
  • the measurement target needs to be the same for all measurement IDs within a single execution condition. That is, there is a need to limit the target of CHO to a single candidate target cell.
  • each measurement ID may be mapped based on each CHO triggering condition.
  • a report configuration (ReportconfigID) and a measurement target ID (MeasObjectID) may be matched together for each measurement ID.
  • the measurement ID since the target of the CHO needs to be limited to a single candidate target cell, the measurement ID may be the same for the measurement ID.
  • the CHO triggering configuration may be configured for one measurement ID as shown in FIG. 28 .
  • the measurement report configuration ID when the measurement report configuration ID is L, it may be a conditional event based on a signal measured based on the same type of RS as the CHO triggering configuration.
  • the condition event may be set based on a measurement parameter for at least one of RSRP, RSRQ, and SINR. That is, the conditional event may not be set in consideration of time or location.
  • the measurement report configuration ID is 3 and the measurement report configuration ID is P may be considered.
  • an event based on at least one of time and location may be set as the NTN CHO triggering configuration. That is, the CHO triggering configuration information may configure both the radio signal measurement-based condition event and the time and location information-based condition event for the corresponding NTN candidate target cell, which will be described later.
  • the NTN CHO triggering condition may be 3 or 4 at most. In this case, it may be determined whether the triggering condition for the corresponding measurement report is independently triggered for a maximum of 3 or 4 measurement IDs. The UE may determine that the CHO condition for the corresponding NTN candidate target cell is satisfied at the time when all conditions are triggered.
  • a plurality of CHO triggering configurations may be configured for one measurement ID.
  • the measurement ID is 0, the measurement report configuration ID is L, the measurement ID is 3, and the measurement report configuration ID is P, both the time and location reporting configuration may be configured to be related. That is, the radio signal measurement-based condition event and the time/location information-based condition event may be configured based on one measurement ID.
  • the UE may determine whether triggering is performed for up to 3 or 4 measurement IDs independently, and may determine that the CHO condition for the corresponding NTN candidate target cell is satisfied at the triggering time point.
  • the CHO triggering configuration may be defined as one of the report types of the existing measurement report configuration.
  • the UE may perform a handover execution procedure to the corresponding candidate target cell according to the CHO execution procedure without reporting to the base station when the triggering condition is satisfied.
  • information on the NTN candidate cell at the CHO configuration level may include information differentiated from the TN candidate cell base station. More specifically, the UE may determine whether to proceed with handover of the NTN cell by using the CHO information received from the NTN cell.
  • the NTN cell target CHO information may include signal strength information. As an example, signal strength may use only RSRP and RSRQ.
  • the NTN cell target CHO information may be set to be the same as the existing TN cell target CHO triggering information (e.g. A3/4/5 event-based setting).
  • the NTN cell target CHO information based on the mobility of the satellite may include a time-based NTN CHO execution condition.
  • the time-based NTN CHO execution condition may be information based on absolute time (e.g. UTC-based or GPS time or ephemeris derivation time or time for synchronization within a satellite system). For example, when there is only one set time, the UE determines that the CHO execution condition for the preset CHO candidate cell is satisfied when the corresponding time T2 arrives. (CondEvent T1)
  • the terminal selects an arbitrary point in time from the first time (T2) to the later time (T4) among the two set times. It may be determined that a CHO execution condition for a CHO candidate cell with a preset time is satisfied. (CondEvent T2)
  • the NTN CHO execution condition may use a time interval (e.g. a time for determining a candidate cell as a final handover target) and an RSRP/RSRP value (e.g. using an A3/4/5 event).
  • a time interval e.g. a time for determining a candidate cell as a final handover target
  • an RSRP/RSRP value e.g. using an A3/4/5 event
  • the terminal receives the first of the two set times (T2) from the later At least one of RSRP, RSRQ, and SINR values may be measured for a preconfigured CHO candidate cell within the interval until the arrival time T4 (CondEvent T2). If a preset triggering condition (CondEvent A3 or A4 or A5) is satisfied within the interval, the UE may determine that the triggering condition meets the CHO execution condition for a preset CHO candidate cell.
  • a preset triggering condition CondEvent A3 or A4 or A5
  • the terminal starts TTT at a time point that meets a preset triggering condition (CondEvent A3 or A4 or A5) and maintains the corresponding event until the TTT end time point, it can be determined that the event triggering condition is satisfied.
  • a preset triggering condition CondEvent A3 or A4 or A5
  • the UE measures at least one of RSRP, RSRQ, and SINR values for a preconfigured CHO candidate cell in advance, and confirms whether the preset triggering condition (CondEvent A3 or A4 or A5) is satisfied. .
  • the UE may determine that the CHO execution condition for the preset CHO candidate cell is satisfied when the time T2 set as the triggering condition arrives while the above-described condition is satisfied. (CondEvent T1)
  • the UE may perform handover based on the location-based NTN CHO execution condition.
  • the location-based NTN CHO execution condition may consider the distance between the UE and the satellite including the serving NTN cell.
  • the terminal may start TTT when the distance between the terminal and the satellite exceeds a threshold.
  • the UE may consider both the distance between the UE and the satellite including the serving NTN cell compared to the distance between the satellites including the neighboring NTN cell. (CondEvent L3)
  • the UE may consider the distance between the UE and the serving NTN cell reference location or the distance between the UE and the serving NTN cell center. (CondEvent L2)
  • the terminal may start the TTT when the distance between the terminal and the reference location or the cell center exceeds a threshold.
  • the UE may consider both the distance between the UE and the serving NTN cell reference position compared to the distance between the neighboring NTN cell reference positions. (CondEvent L4) As another example, the UE may consider both the distance between the UE and the serving NTN cell center versus the distance between the neighboring NTN cell centers. (CondEvent L5)
  • the UE can determine that the CHO execution condition for the CHO candidate cell is satisfied when at least one or more of the set triggering conditions are satisfied. have.
  • the UE may determine that the CHO execution condition for the CHO candidate cell is satisfied when all of the set triggering conditions are satisfied. .
  • FIG. 29 is a diagram illustrating a method of performing a measurement report for handover of a TN cell to which the present disclosure can be applied. Referring to FIG.
  • a terminal 2920 may receive a service from an NTN source base station 2910 .
  • the terminal 2920 may receive CHO information for the NTN cell from the NTN source base station 2910 based on the measurement report or the network determination.
  • the terminal 2920 may receive NTN cell handover information through RRC signaling.
  • the UE 2920 may perform measurement based on the received CHO information and measurement report information for the TN cell.
  • the terminal 2920 may start a triggering timer and determine handover to the TN cell.
  • the terminal 2920 may transmit a measurement report message to the NTN source base station 2910 for handover to the TN cell.
  • the terminal 2920 may request uplink scheduling from the NTN source base station 2910 .
  • the terminal 2910 may receive configuration information for the CHO condition for the NTN in advance.
  • the terminal 2910 may determine whether the execution condition is satisfied in consideration of condition events for the NTN cell based on the configuration information received in advance.
  • the terminal 2920 may start a handover procedure to the target NTN cell based on the NTN target base station 2930 .
  • the terminal 2920 intends to perform a handover to the TN cell based on the mobility of the terminal and transmits a report on this to the NTN source base station 2910, but based on the handover to the NTN cell, this may not be performed. have. Accordingly, the NTN source base station 2910 may not recognize whether the corresponding terminal 2920 is in a state in which handover to a specific TN base station is required. In consideration of the above, the terminal 2920 transmits the TN cell measurement result that could not be transmitted to the existing NTN source base station 2910 after the handover to the NTN target base station 2930 is completed, and the handover is completed to the NTN target base station 2930 ) can be transmitted.
  • the terminal 2920 may transmit the TN cell measurement result in an RRC reconfiguration complete message transmitted during the handover procedure for the target NTN cell.
  • the terminal 2920 may transmit a TN cell measurement result value to the NTN target base station 2930 based on a general measurement report procedure after the handover procedure is completely terminated, and is not limited to the above-described embodiment. does not Here, the terminal 2920 may store the TN cell measurement result that has not been reported to the NTN source base station 2910 without deleting it according to the handover between the target NTN cells, and through this, the TN cell measurement result value is stored in the NTN target base station ( 2930) can be transmitted. Thereafter, the terminal 2920 may perform handover for the TN cell based on the TN base station 2940 .
  • FIG. 30 is a diagram illustrating a method of performing a measurement report for handover of a TN cell to which the present disclosure can be applied.
  • a terminal 3020 may receive a service from an NTN source base station 3010 .
  • the terminal 3020 may receive the CHO information for the NTN cell from the NTN source base station 3010 based on the measurement report or the network determination.
  • the terminal 3020 may receive NTN cell handover information through RRC signaling. Thereafter, the terminal 3020 may perform measurement based on the received CHO information and measurement report information for the TN cell.
  • the terminal 3020 may start a triggering timer and determine handover to the TN cell. Thereafter, the terminal 3020 may perform a measurement report to the NTN source base station 3010 for handover to the TN cell.
  • the handover between NTN cells may be started in a state in which the terminal 3020 does not receive the RRC reconfiguration message including the handover indication information for the TN cell.
  • the terminal 3010 may receive configuration information for the CHO condition for the NTN in advance.
  • the terminal 3010 may determine whether the execution condition is satisfied in consideration of condition events for the NTN cell based on the previously received configuration information.
  • the terminal 3020 may start the handover procedure to the target NTN cell based on the NTN target base station 3030 .
  • the terminal 3020 transmits a TN cell measurement report to the NTN source base station 3010 to perform handover to the TN cell based on the mobility of the terminal, but based on the handover to the NTN cell, the RRC reconfiguration message cannot be received.
  • the NTN source base station 3010 may recognize that the terminal 3020 should perform handover to a specific TN cell based on the TN cell measurement report. Also, the NTN source base station 3010 may recognize that the terminal 3020 has performed handover to the NTN target base station 3030 based on the CHO procedure. In this case, as an example, the NTN source base station 3010 may share the TN cell measurement report result provided by the terminal 3020 with the NTN target base station 3030 . That is, the NTN source base station 3010 may inform the NTN target base station 3030 that the terminal 3020 needs handover to a specific TN cell.
  • the NTN target base station 3030 may transmit a handover request message to the TN base station 3040 including a specific TN cell based on the information received from the NTN source base station 3010 . Thereafter, the NTN target base station 3030 may receive a handover request confirmation message through the admission control procedure of the TN base station 3040 . Through this, the NTN target base station 3030 may obtain information on the TN cell required for the handover of the terminal 3020 . Thereafter, the NTN target base station 3030 may transmit an RRC reconfiguration message including a handover command to a specific TN cell to the terminal 3020 . The terminal 3020 may perform handover to the TN cell based on the RRC reconfiguration message.
  • a terminal 3120 may receive a service from an NTN source base station 3110 .
  • the terminal 3120 may receive the CHO information for the NTN cell from the NTN source base station 3110 based on the measurement report or the network determination.
  • the terminal 3120 may receive NTN cell handover information through RRC signaling. Thereafter, the UE 3120 may perform measurement based on the received CHO information and measurement report information for the TN cell.
  • the terminal 3120 may start a triggering timer and determine handover to the TN cell. Thereafter, the terminal 3120 may perform a measurement report to the NTN source base station 3110 for handover to the TN cell.
  • a case in which the handover between NTN cells fails in a state in which the terminal 3120 does not receive the RRC reconfiguration message including the handover indication information for the TN cell may be considered. That is, a case in which radio link failure (RLF) occurs in the terminal 3120 may be considered. Accordingly, the terminal 3120 may not receive the RRC reconfiguration message from the NTN source base station 3110 and may not be able to access the NTN target base station 3130 at the same time. In this case, in order for the terminal 3120 to receive the service again, an RRC connection establishment procedure may be started.
  • PLMN Public Land Mobile Network
  • EPLMN Equivalent Public Land Mobile Network
  • the UE 3120 may perform CHO execution evaluation for candidate cells and attempt CHO.
  • the UE 3120 may perform a cell reselection procedure for TN and NTN cells based on an RRC re-establishment procedure.
  • the UE 3120 may perform cell reselection procedures for the NTN CHO candidate cell, the TN cell, and other NTN cells at the same time point without distinction.
  • the cell reselection procedure is performed while the T311 timer is running and may be terminated when it expires.
  • the TN and NTN may be connected to the same CN although RATs are set differently. That is, it can be operated in the same NG-RAN in the relationship between the TN and the NTN.
  • the terminal 3120 may receive the previous access cell confirmation and UE context information required for the RRC reconfiguration procedure after cell reselection for the TN cell.
  • a terminal 3220 may receive a service from an NTN source base station 3210 .
  • the terminal 3220 may receive the CHO information for the NTN cell from the NTN source base station 3210 based on the measurement report or the determination of the network.
  • the terminal 3220 may receive NTN cell handover information through RRC signaling. Thereafter, the terminal 3220 may perform measurement based on the received CHO information and measurement report information for the TN cell.
  • the terminal 3220 may start a triggering timer and determine handover to the TN cell. Thereafter, the terminal 3220 may perform a measurement report to the NTN source base station 3210 for handover to the TN cell.
  • a case in which the handover between NTN cells fails in a state in which the terminal 3220 does not receive the RRC reconfiguration message including the handover indication information for the TN cell may be considered. That is, a case in which RLF occurs in the terminal 3220 may be considered. Accordingly, the terminal 3220 may not receive the RRC reconfiguration message from the NTN source base station 3210 and may not be able to access the NTN target base station 3230 at the same time. In this case, in order for the terminal 3220 to receive the service again, an RRC connection establishment procedure may be started.
  • the TN is the same Visited Public Land Mobile Network (VPLMN) or Home Public Land Mobile Network (HPLMN) as the NTN may be considered.
  • VPN Visited Public Land Mobile Network
  • HPLMN Home Public Land Mobile Network
  • the UE 3220 may perform CHO execution evaluation for candidate cells and attempt CHO.
  • the UE may select other NTN cells through the cell reselection procedure.
  • a case in which the terminal 3220 cannot find a suitable cell in the NTN may be considered. That is, the terminal 3220 may not find the NTN cell until the aforementioned T311 expires. In this case, the terminal 3220 may transition to an RRC idle (RRC IDLE) mode.
  • RRC idle RRC idle
  • the terminal 3220 sets the TN cell in which the measurement report is triggered or the measurement report is transmitted to the NTN base station as the highest priority, and performs a cell reselection procedure based on this to determine whether the TN cell is a suitable cell can be checked. At this time, if the TN cell is a suitable cell, the terminal 3220 may start the RRC connection establishment procedure.
  • FIG 33 is a flowchart illustrating a method of performing handover of a TN cell to which the present disclosure can be applied.
  • the UE may receive CHO information for the NTN and TN cell from the NTN source base station (S3310). Thereafter, the UE performs a measurement on the TN cell and handover to the TN cell based on this. It is possible to start a triggering timer for , as described above. (S3320) That is, when the execution condition is satisfied based on the CHO information for the TN cell set in advance, the UE sets a triggering timer for handover to the TN cell. can start In this case, as described above, the TTT may proceed in a time interval in which a situation in which a specific criterion for an event set for triggering a measurement report operation is satisfied must be maintained.
  • CHO it may be a time period in which a situation in which a specific criterion for an event set as a handover execution condition for a specific CHO candidate cell is satisfied must be maintained.
  • handover may proceed even if the terminal does not move based on the movement of the satellite.
  • a case in which a handover procedure is performed from the NTN source base station to the NTN target base station based on the CHO information may be considered (S3330).
  • the triggering timer is stopped, and the NTN When the handover expires, it may be started (or restarted), as described above.
  • the handover may proceed to the TN cell without stopping the triggering timer.
  • the triggering timer for handover of the TN cell is not stopped, and the start of the NTN handover procedure may be delayed, as described above.
  • 34 is a flowchart illustrating a method of performing handover of a TN cell to which the present disclosure can be applied.
  • the UE may receive CHO information for NTN and TN cells from the NTN source base station (S3410). Thereafter, the UE may perform handover to the NTN cell based on the CHO information (S3420). ) In this case, for example, handover of the NTN cell may be performed based on the movement of the satellite. Accordingly, the handover of the NTN cell may be frequent based on time and location, and the signaling load may increase when the CHO information of the TN cell is newly set for each handover. In consideration of the above, when the handover to the NTN cell is in progress, the UE may maintain the CHO information of the TN cell (S3330).
  • the TN cell between the NTN cells CHO information is shared, and CHO information for a TN cell may be maintained in the terminal based on the confirmation of the TN base station, as described above.
  • 35 is a flowchart illustrating a method of performing handover of a TN cell to which the present disclosure can be applied.
  • the UE may receive CHO information for the NTN and TN cell from the NTN source base station (S3510). Thereafter, the UE performs measurement on the TN cell and handover to the TN cell based on this. It is possible to start a triggering timer for , as described above. (S3520) That is, when the execution condition is satisfied based on the CHO information for the TN cell set in advance, the UE sets a triggering timer for handover to the TN cell. can start Thereafter, the UE may determine handover to the TN cell (S3530).
  • the NTN CHO execution condition is satisfied and the target The handover may proceed to the NTN cell (S3540).
  • the NTN source base station and the NTN target base station share the measurement for the TN cell, and the handover may proceed to the TN cell based on the handed over target NTN cell, This is the same as described above. (S3550)
  • a first device 3600 and a second device 3650 may communicate with each other.
  • the first device 3610 may be a base station device
  • the second device 3650 may be a terminal device.
  • both the first device 3610 and the second device 3650 may be terminal devices. That is, the first device 3610 and the second device 3650 may be devices that perform mutual communication based on sidelink communication.
  • the base station device 3600 when the first device 3610 is a base station device and the second device 3650 is a terminal device, the base station device 3600 includes a processor 3620, an antenna unit 3612, a transceiver 3614, memory 3616 .
  • the processor 3620 performs baseband-related signal processing and may include an upper layer processing unit 3630 and a physical layer processing unit 3640 .
  • the upper layer processing unit 3630 may process an operation of a medium access control (MAC) layer, a radio resource control (RRC) layer, or a higher layer.
  • the physical layer processing unit 3640 may process an operation of the physical (PHY) layer (eg, uplink reception signal processing, downlink transmission signal processing, sidelink transmission signal processing, sidelink reception signal processing). .
  • the processor 3620 may control the overall operation of the base station device 3600 in addition to performing baseband-related signal processing.
  • the antenna unit 3612 may include one or more physical antennas, and when it includes a plurality of antennas, it may support multiple input multiple output (MIMO) transmission and reception.
  • the transceiver 3614 may include a radio frequency (RF) transmitter and an RF receiver.
  • the memory 3616 may store information processed by the processor 3620 , software related to the operation of the base station device 3600 , an operating system, an application, and the like, and may include components such as a buffer.
  • the descriptions in the examples of the present invention may be equally applied, and overlapping descriptions will be omitted.
  • Example methods of the present disclosure are expressed as a series of operations for clarity of description, but this is not intended to limit the order in which the steps are performed, and if necessary, each step may be performed simultaneously or in a different order.
  • other steps may be included in addition to the illustrated steps, other steps may be included except some steps, or additional other steps may be included except some steps.
  • various embodiments of the present disclosure may be implemented by hardware, firmware, software, or a combination thereof.
  • ASICs Application Specific Integrated Circuits
  • DSPs Digital Signal Processors
  • DSPDs Digital Signal Processing Devices
  • PLDs Programmable Logic Devices
  • FPGAs Field Programmable Gate Arrays
  • general purpose It may be implemented by a processor (general processor), a controller, a microcontroller, a microprocessor, and the like.
  • the scope of the present disclosure includes software or machine-executable instructions (eg, operating system, application, firmware, program, etc.) that cause operation according to the method of various embodiments to be executed on a device or computer, and such software or and non-transitory computer-readable media in which instructions and the like are stored and executed on a device or computer.
  • software or machine-executable instructions eg, operating system, application, firmware, program, etc.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Astronomy & Astrophysics (AREA)
  • General Physics & Mathematics (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

La présente invention peut concerner un procédé de fonctionnement d'un terminal prenant en charge un NTN et un TN dans un système de communication sans fil. Dans ce cas, le procédé de fonctionnement du terminal peut comprendre les étapes consistant à : recevoir des informations de transfert intercellulaire conditionnel (CHO) concernant une cellule NTN et une cellule TN ; et réaliser un transfert intercellulaire de la cellule TN en tenant compte du fait que le transfert intercellulaire de la cellule NTN est réalisé.
PCT/KR2022/004350 2021-04-02 2022-03-28 Procédé et appareil de communication entre un réseau non terrestre et un réseau terrestre et terminal dans un système de communication sans fil Ceased WO2022211426A1 (fr)

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WO2025058342A1 (fr) * 2023-09-12 2025-03-20 Samsung Electronics Co., Ltd. Procédé et appareil de transfert conditionnel sans rach dans un système de communication sans fil
WO2025059814A1 (fr) * 2023-09-18 2025-03-27 上海移远通信技术股份有限公司 Procédé de transfert intercellulaire de satellite de réseau non terrestre, dispositif terminal et dispositif de réseau

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