Method and apparatus for managing UE cell reselection priority in next generation mobile communication system

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. The invention relates to a method and an apparatus for cell reselection of UE. The present disclosure relates to a method performed by a UE having an unmanned aerial vehicle (UAV) in a wireless communication system and an apparatus for performing the method. The method comprises the steps of: receiving system information from a base station, the system information comprising at least one of a first cell reselection priority (CRP) or a second CRP for each of a plurality of frequencies; determining cell reselection priorities of the plurality of frequencies based on the system information; measuring frequencies based on the cell reselection priorities of the plurality of frequencies; and reselecting a cell satisfying a cell reselection criterion based on the frequency measurement, in which the first CRP is a CRP defined for an existing UAV UE, and the second CRP is a CRP defined for a UE with UAV functionality.

Description

Technical Field

[0001] The present disclosure relates to a method and apparatus for managing cell reselection priorities of a terminal in a next generation mobile communication system. Background Art

[0002] The 5th generation (5G) mobile communication technology defines a wider frequency band so that high transmission rates and new services are possible, and can be realized not only in the "sub-6 GHz" frequency band such as 3.5 GHz, but also in the "higher than 6 GHz" frequency band called millimeter waves including 28 GHz and 39 GHz. In addition, it has been considered to realize 6G mobile communication technology (called super 5G system) in the terahertz frequency band (for example, 95 GHz to 3 THz frequency band) in order to realize a transmission rate fifty times faster than 5G mobile communication technology and an ultra-low latency of one tenth of 5G mobile communication technology.

[0003] At the beginning of the development of 5G mobile communication technology, in order to support services and meet performance requirements related to enhanced mobile broadband (eMBB), ultra-reliable low latency communication (URLLC) and massive machine type communication (mMTC), standardization work on beamforming and massive MIMO has been ongoing for mitigating radio wave path loss and increasing radio wave transmission distance in mmWave, supporting parameter sets for efficient utilization of mmWave resources and dynamic operation of time slot formats (e.g., operation of multiple subcarrier spacings), initial access technology for supporting multi-beam transmission and broadband, definition and operation of BWP (bandwidth part), new channel coding methods such as LDPC (low-density parity check) codes for large-volume data transmission and polar codes for highly reliable transmission of control information, L2 pre-processing, and network slicing for providing dedicated networks dedicated to specific services.

[0004] Currently, there are ongoing discussions on improvements and performance enhancements of initial 5G mobile communication technologies in consideration of the services that 5G mobile communication technologies are to support, and there is physical layer standardization on technologies such as V2X (Vehicle-to-Everything), which is used to assist driving determination of autonomous vehicles based on information about the location and status of vehicles transmitted by vehicles and for enhancing user convenience, NR-U (New Radio Unlicensed), which is a system operation intended to comply with various regulatory-related requirements in unlicensed bands, NR UE power saving, non-terrestrial networks (NTN), which are UE-satellite direct communications for providing coverage in areas where communications with terrestrial networks are unavailable, and positioning.

[0005] In addition, the standardization of air interface architecture / protocols has been ongoing, involving technologies such as: Industrial Internet of Things (IIoT) to support new services through interworking and convergence with other industries, IAB (Integrated Access and Backhaul) for providing nodes for network service area expansion by supporting wireless backhaul links and access links in an integrated manner, mobility enhancement including conditional handover and DAPS (Dual Active Protocol Stack) handover, and two-step random access technology for simplifying the random access process (2-step RACH for NR). In terms of system architecture / services, 5G baseline architecture (e.g., service-based architecture or service-based interface) is also being standardized to combine network function virtualization (NFV) and software-defined network (SDN) technologies, as well as mobile edge computing (MEC) for receiving services based on UE location.

[0006] With the commercialization of 5G mobile communication systems, the already exponentially growing number of connected devices will be connected to the communication network, and it is therefore expected that enhanced functions and performance of the 5G mobile communication system and integrated operation of connected devices will be necessary. To this end, new research is planned in the following areas: effectively supporting extended reality (XR) such as AR (augmented reality), VR (virtual reality), MR (mixed reality), etc.; improving 5G performance and reducing complexity using artificial intelligence (AI) and machine learning (ML); AI service support; metadata service support; and drone communication.

[0007] Furthermore, such developments in 5G mobile communication systems will serve as a foundation for developing new waveforms for providing coverage in the terahertz band of 6G mobile communication technology, multi-antenna transmission technologies such as full-dimensional MIMO (FD-MIMO), array antennas, and massive antennas, metamaterial-based lenses and antennas for improving coverage of terahertz band signals, high-dimensional spatial multiplexing technologies using OAM (orbital angular momentum), and RIS (reconfigurable smart surface), and full-duplex technologies for increasing the frequency efficiency of 6G mobile communication technology and improving system networks, AI-based communication technologies for achieving system optimization by utilizing satellites and AI (artificial intelligence) from the design stage and internalizing end-to-end AI support functions, and next-generation distributed computing technologies for realizing services at a level of complexity that exceeds the limits of UE operating capabilities by utilizing ultra-high-performance communication and computing resources. Summary of the invention

[0008] Technical issues The technical objective to be achieved in various embodiments of the present disclosure is to provide a method and apparatus for managing the cell reselection priority of a terminal in a mobile communication system.

[0009] In addition, the technical objective to be achieved in various embodiments of the present disclosure is to provide a cell reselection method and apparatus for an air terminal in a mobile communication system.

[0010] Technical Solution According to various embodiments of the present disclosure, a method performed by a terminal with a drone function in a wireless communication system may include: receiving system information from a base station, the system information including at least one of a first cell reselection priority (CRP) or a second CRP for each of a plurality of frequencies; determining the cell reselection priorities of the plurality of frequencies based on the system information; performing frequency measurement based on the cell reselection priorities of the plurality of frequencies; and reselecting a cell that meets a cell reselection criterion based on the frequency measurement, wherein the first CRP is a CRP defined for a traditional UAV terminal and the second CRP is a CRP defined for a terminal with a UAV function.

[0011] In addition, according to various embodiments of the present disclosure, a terminal with an unmanned aerial vehicle (UAV) function in a wireless communication system may include: a transceiver; and a controller, wherein the controller may be configured to control: receiving system information from a base station, the system information including at least one of a first cell reselection priority (CRP) or a second CRP for each of a plurality of frequencies; determining the cell reselection priorities of the plurality of frequencies based on the system information; performing frequency measurement based on the cell reselection priorities of the plurality of frequencies; and reselecting a cell that meets the cell reselection criteria based on the frequency measurement, wherein the first CRP may be a CRP defined for a traditional UAV terminal, and the second CRP may be a CRP defined for a terminal with a UAV function. The technical objectives to be achieved in various embodiments of the present disclosure are not limited to those described above, and a person skilled in the art to which the present disclosure belongs will clearly understand other unmentioned technical objectives through the following description.

[0012] Technical Effects According to various embodiments of the present disclosure, a method and apparatus for managing a cell reselection priority of a terminal in a mobile communication system may be provided.

[0013] In addition, according to various embodiments of the present disclosure, a cell reselection method and apparatus for an air terminal in a mobile communication system may be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a diagram showing the architecture of an LTE system according to an embodiment of the present disclosure.

[0015] Figure 2 is a diagram showing a structure of a radio protocol in an LTE system according to an embodiment of the present disclosure.

[0016] Figure 3 is a diagram showing the architecture of a next generation mobile communication system according to an embodiment of the present disclosure.

[0017] Figure 4 is a diagram showing a structure of a radio protocol in a next generation mobile communication system according to an embodiment of the present disclosure.

[0018] Figure 5 A cell reselection process performed by a UE in a next generation mobile communication system according to an embodiment of the present disclosure is described.

[0019] Figure 6 is a diagram depicting a cell reselection procedure performed by an air UE in a next generation mobile communication system according to an embodiment of the present disclosure.

[0020] Figure 7 is a diagram depicting a cell reselection procedure performed by an air UE in a next generation mobile communication system according to an embodiment of the present disclosure.

[0021] Figure 8 is a diagram depicting a cell reselection procedure performed by an air UE in a next generation mobile communication system according to an embodiment of the present disclosure.

[0022] Fig. 9 is a diagram depicting a cell reselection procedure performed by an air UE in a next generation mobile communication system according to an embodiment of the present disclosure.

[0023] Fig.10 is a diagram depicting a cell reselection procedure performed by an air UE in a next generation mobile communication system according to an embodiment of the present disclosure.

[0024] Fig.11 is a diagram showing the structure of a UE according to an embodiment of the present disclosure.

[0025] Fig.12 is a diagram showing a structure of a base station according to an embodiment of the present disclosure. Specific embodiments Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Here, it should be noted that in the accompanying drawings, the same components are represented by the same symbols as much as possible. In addition, the detailed description of known functions and configurations that may obscure the main points of the present disclosure will be omitted.

[0027] In the description of the following embodiments, the description of technical details that are well known in the art and not directly related to the present disclosure may be omitted. This is to convey the subject matter of the present disclosure more clearly without ambiguity by omitting unnecessary descriptions.

[0028] Likewise, in the accompanying drawings, some elements are exaggerated, omitted or only briefly outlined. In addition, the size of each element does not necessarily reflect the actual size. The same or similar reference numerals are used throughout the accompanying drawings to refer to the same or similar parts.

[0029] The advantages and features of the present disclosure and the methods for achieving the advantages and features will become more clear through the following detailed description of the embodiments in conjunction with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below, but can be implemented in various different ways. The embodiments are provided only to complete the present disclosure and fully inform the technical personnel in the field to which the present disclosure belongs of the scope of the present disclosure, and the present disclosure is limited only by the scope of the claims. The same reference symbols are used throughout the description to refer to the same parts.

[0030] At the same time, it should be understood that the blocks of the flowchart and the combination of the flowchart can be executed by computer program instructions. These computer program instructions can be loaded onto a processor of a general-purpose computer, a special-purpose computer, or a programmable data processing device, and the instructions executed by the computer or programmable data processing device processor create a means for performing the functions described in the flowchart box. In order to achieve the function in some way, the computer program instructions can also be stored in a computer-usable or readable memory suitable for a special-purpose computer or a programmable data processing device, and the computer program instructions stored in the computer-usable or readable memory can produce an article of manufacture containing a device for performing the functions described in the flowchart box. Since the computer program instructions can be loaded onto a computer or a programmable data processing device, when the computer program instructions are executed as a process having a series of operations on a computer or a programmable device, they can provide steps for performing the functions described in the flowchart box.

[0031] In addition, each block of the flowchart may correspond to a module, a segment, or a code that contains one or more executable instructions for performing one or more logical functions, or corresponds to a portion thereof. It should also be noted that in some alternative cases, the functions described by the blocks may be performed in an order different from the order listed. For example, two blocks listed in order may be executed substantially simultaneously or in reverse order, depending on the corresponding functions.

[0032] Here, the words "unit", "module" etc. used in the embodiment may refer to software components or hardware components that can perform functions or operations, such as FPGA or ASIC. However, "unit" etc. are not limited to software or hardware. Units etc. may be configured to reside in an addressable storage medium or drive one or more processors. For example, units etc. may refer to components such as software components, object-oriented software components, class components or task components, processes, functions, attributes, procedures, subroutines, program code segments, drivers, firmware, microcodes, circuits, data, databases, data structures, tables, arrays or variables. The functions provided by components and units may be combinations of smaller components and units, or may be combined with other components and units to form larger components and units. In addition, components and units may be implemented to drive one or more processors in a device or a secure multimedia card.

[0033] In the following description, the term "base station" refers to a main agent that allocates resources to a terminal, and may be at least one of a node B, a BS, an eNB (eNode B), a gNB (gNode B), a wireless access unit, a base station controller, or a network node. The term "terminal" may refer to at least one of a user equipment (UE), a mobile station (MS), a cellular phone, a smart phone, a computer, or a multimedia system having a communication function. In addition, the embodiments of the present disclosure may be applied to other communication systems having a similar technical background or channel type to the embodiments of the present disclosure described below. In addition, the embodiments of the present disclosure may be applied to other communication systems with some modifications without significantly deviating from the scope of the present disclosure. For example, this may include the fifth generation mobile communication technology (5G, new radio, NR) developed after LTE-A, and the term 5G hereinafter may be a concept including existing LTE, LTE-A, and other similar services. In addition, those skilled in the art should understand that the present disclosure is applicable to other communication systems without making significant modifications that deviate from the scope of the present disclosure.

[0034] For the convenience of description, the terms used in the following description to identify an access node, indicate a network entity or a network function (NF), indicate a message, indicate an interface between network entities, and indicate various identification information are used as illustrations. Therefore, the present disclosure is not limited by the terms described later, and other terms referring to objects with equivalent technical meanings may be used.

[0035] For ease of explanation, some terms and names defined in the 3GPP (3rd Generation Partnership Project) LTE (Long Term Evolution) standard and / or the 3GPP NR (New Radio) standard may be used in the following description. However, the present disclosure is not limited to the above terms and names and can be equally applied to systems conforming to other standards.

[0036] Figure 1is a diagram showing the architecture of an LTE system according to an embodiment of the present disclosure.

[0037] Reference Figure 1 , as shown in the figure, the radio access network of the LTE system may be composed of a next generation base station (evolved Node B, ENB, Node B or base station) 1-05, 1-10, 1-15 or 1-20, a mobility management entity (MME) 1-25 and a serving gateway (S-GW) 1-30. A user equipment (UE or terminal) 1-35 may be connected to an external network through the ENB 1-05, 1-10, 1-15 or 1-20 and the S-GW 1-30.

[0038] exist Figure 1 In the LTE system, ENBs 1-05, 1-10, 1-15, and 1-20 correspond to existing Node Bs of the Universal Mobile Telecommunications System (UMTS). ENBs 1-05, 1-10, 1-15, or 1-20 are connected to UEs 1-35 through wireless channels, but perform more complex functions than existing Node Bs. In the LTE system, all user services including real-time services such as VoIP (Voice over IP) can be provided through shared channels. Therefore, a device may be required to perform scheduling based on the collected state information about the buffer, available transmit power, and channel of the UE, and ENBs 1-05, 1-10, 1-15, and 1-20 may be responsible for this. In a typical case, one ENB may control multiple units. In order to achieve a data rate of, for example, 100 Mbps in a bandwidth of, for example, 20 MHz, the LTE system may utilize Orthogonal Frequency Division Multiplexing (OFDM) as a wireless access technology. In addition, the ENB may apply adaptive modulation and coding (referred to as AMC) to determine the modulation scheme and channel coding rate according to the channel state of the UE. The S-GW 1-30 is an entity that provides data bearers, and may create and delete data bearers under the control of the MME 1-25. The MME 1-25 is an entity responsible for various control functions including a mobility management function for the UE 1-35, and may be connected to a plurality of ENBs.

[0039] Figure 2 is a diagram showing a structure of a radio protocol in an LTE system according to an embodiment of the present disclosure.

[0040] Reference Figure 2 , in UE or ENB, the radio protocol of the LTE system may include a packet data convergence protocol (PDCP) 2-05 or 2-40, a radio link control (RLC) 2-10 or 2-35, and a medium access control (MAC) 2-15 or 2-30. PDCP (Packet Data Convergence Protocol) 2-05 or 2-40 may perform compression and decompression of IP headers. The main functions of PDCP may be summarized as follows.

[0041] - Header compression and decompression function (Header compression and decompression: ROHC only) - User data transmission function (transmission of user data) - In-sequence delivery function (in-sequence delivery of upper layer PDUs during PDCP re-establishment of RLC AM) - Reordering functionality (for split bearers in DC (supports RLC AM only): PDCP PDU routing for transmission and PDCP PDU reordering for reception) - Duplicate detection function (duplicate detection of lower layer SDUs during PDCP re-establishment of RLC AM) - Retransmission functionality (retransmission of PDCP SDUs at handover and, for split bearers in DC, retransmission of PDCP PDUs during PDCP data recovery for RLC AM) - Encryption and decryption functions (encryption and decryption) - Timer-based SDU discard function (Timer-based SDU discard in uplink) - Radio Link Control (referred to as RLC) 2-10 or 2-35 can reconfigure the PDCP PDU (Packet Data Unit) to a suitable size and perform Automatic Repeat Request (ARQ) operations. The main functions of RLC can be summarized as follows.

[0042] - Data transmission function (transmission of upper layer PDU) - ARQ function (error correction through ARQ (for AM data transmission only)) - Concatenation, segmentation and reassembly function (concatenation, segmentation and reassembly of RLC SDU (only for UM and AM data transmission)) - Re-segmentation function (resegmentation of RLC data PDU (only for AM data transmission)) - Reordering function (reordering of RLC data PDUs (only for UM and AM data transmission)) - Duplicate detection function (Duplicate detection (only for UM and AM data transmission)) - Error detection function (Protocol error detection (for AM data transmission only)) - RLC SDU discard function (RLC SDU discard (only for UM and AM data transmission)) - RLC re-establishment function (RLC re-establishment) MAC 2-15 or 2-30 can be connected with multiple RLC entities in the UE, and it can multiplex RLC PDUs into MAC PDUs and demultiplex MAC PDUs into RLC PDUs. The main functions of MAC can be summarized as follows.

[0043] - Mapping function (mapping between logical channels and transport channels) - Multiplexing and demultiplexing functions (multiplexing / demultiplexing MAC SDUs belonging to one or different logical channels into / from transport blocks (TBs) delivered by the physical layer on transport channels) -Scheduling information reporting function (Scheduling information reporting) - HARQ function (error correction through HARQ) - Priority handling between logical channels (priority handling between logical channels of a UE) - Priority handling between UEs (priority handling between UEs through dynamic scheduling) - MBMS service identification function (MBMS service identification) - Transmission format selection function (Transmission format selection) - Fill function (fill) The physical (PHY) layer 2-20 or 2-25 may convert higher layer data into OFDM symbols through channel coding and modulation and transmit the OFDM symbols through a wireless channel, or it may demodulate OFDM symbols received through a wireless channel, perform channel decoding, and forward the result to an upper layer.

[0044] Figure 3 is a diagram showing the architecture of a next generation mobile communication system according to an embodiment of the present disclosure.

[0045] Reference Figure 3 As shown in the figure, the radio access network of the next generation mobile communication system (hereinafter referred to as NR or 5g) can be composed of a new radio node B (hereinafter referred to as NR gNB or NR base station) 3-10 and a new radio core network (NR CN) 3-05. The new radio user equipment (hereinafter referred to as NR UE or terminal) 3-15 can be connected to an external network through the NR gNB 3-10 and the NR CN 3-05.

[0046] exist Figure 3In the present invention, the NR gNB 3-10 may correspond to the evolved Node B (eNB) of the existing LTE system. The NR gNB 3-10 may be connected to the NR UE 3-15 through a wireless channel, and it may provide services superior to those of the existing Node B. In the next generation mobile communication system, all user services may be provided through a shared channel. Therefore, an entity that performs scheduling by collecting status information of each UE, such as buffer status, available transmission power status, and channel status, may be required, and the NR gNB 3-10 may be responsible for this work. In a typical case, one NR gNB 3-10 controls multiple cells. In order to achieve ultra-high-speed data transmission compared to the current LTE, a bandwidth exceeding the existing maximum bandwidth may be utilized. In addition, beamforming technology may also be used with orthogonal frequency division multiplexing (OFDM) used as a wireless access technology. In addition, an adaptive modulation and coding (AMC) scheme may be applied, which determines the modulation scheme and channel coding rate to match the channel status of the UE. The NRCN 3-05 may perform functions such as mobility support, bearer configuration, and quality of service (QoS) configuration. NR CN 3-05 is an entity responsible not only for mobility management but also for various control functions of UE 3-15, and can be connected to multiple base stations. In addition, the next generation mobile communication system can interwork with the existing LTE system, and NR CN 3-05 can be connected to MME 3-25 through a network interface. MME 3-25 is connected to eNB 3-30 which is an existing base station.

[0047] Figure 4 is a diagram showing a structure of a radio protocol in a next generation mobile communication system according to an embodiment of the present disclosure.

[0048] Figure 4 is a diagram showing a radio protocol structure of a next-generation mobile communication system to which the present disclosure can be applied.

[0049] Reference Figure 4 , in UE or NR gNB, the radio protocol of the next generation mobile communication system may include NR SDAP4-01 or 4-45, NR PDCP 4-05 or 4-40, NR RLC 4-10 or 4-35 and NR MAC 4-15 or 4-30.

[0050] The main functions of NR SDAP 4-01 or 4-45 may include some of the following functions.

[0051] - User data transmission function (user plane data transmission) - Mapping function between uplink and downlink QoS flows and data bearers (mapping between QoS flows and DRBs for both DL and UL) - QoS flow ID marking function for uplink and downlink (marking QoS flow ID in both DL packets and UL packets) - Functionality to map Reflective QoS flows to data bearers of uplink SDAP PDUs (Mapping of Reflective QoS flows to DRBs for UL SDAP PDUs) For the SDAP entity, the UE can configure whether to use the header of the SDAP entity through an RRC message, or whether to use the SDAP function for each PDCP entity, bearer or logical channel. In addition, if the SDAP header is configured, the NAS reflected QoS 1-bit indication and AS reflected QoS 1-bit indication of the SDAP header can instruct the UE to update or reconfigure the mapping information between the QoS flow and the data bearer for the uplink and downlink. The SDAP header may include QoS flow ID information indicating QoS. QoS information can be used as data processing priority and scheduling information to support smooth services.

[0052] The main functions of NR PDCP 4-05 or 4-40 may include some of the following functions.

[0053] - Header compression and decompression function (Header compression and decompression: ROHC only) - User data transmission function (transmission of user data) - In-sequence delivery function (sequential delivery of upper layer PDUs) - Out-of-order delivery function (out-of-order delivery of upper layer PDU) - Reordering function (for reordering of received PDCP PDUs) - Duplicate detection function (duplicate detection of lower layer SDU) - Retransmission function (retransmission of PDCP SDU) - Encryption and decryption functions (encryption and decryption) - Timer-based SDU discard function (Timer-based SDU discard in uplink) In the above description, the reordering function of the NR PDCP entity may indicate reordering of PDCP PDUs received from a lower layer in sequence based on a PDCP sequence number (SN), and may include delivering data to an upper layer in a reordered order, directly delivering data without considering the order, recording lost PDCP PDUs by reordering, reporting the status of lost PDCP PDUs to the transmitting side, or requesting retransmission of lost PDCP PDUs.

[0054] The main functions of NR RLC 4-10 or 4-35 may include some of the following functions.

[0055] - Data transmission function (transmission of upper layer PDU) - In-sequence delivery function (sequential delivery of upper layer PDUs) - Out-of-order delivery function (out-of-order delivery of upper layer PDU) - ARQ function (error correction through ARQ) - Concatenation, segmentation and reassembly function (concatenation, segmentation and reassembly of RLC SDU) -Re-segmentation function (resegmentation of RLC data PDU) - Reordering function (reordering of RLC data PDUs) - Duplicate detection function (Duplicate detection) - Error detection function (protocol error detection) - RLC SDU discard function (RLC SDU discard) - RLC re-establishment function (RLC re-establishment) In the above description, the sequential delivery of the NR RLC entity may indicate sequential delivery of the RLC SDU received from the lower layer to the upper layer, and may include: when several RLC SDUs belonging to one original RLC SDU are received after segmentation, reassembling and delivering the RLC SDU; reordering the received RLC PDU based on the RLC sequence number (SN) or PDCP SN; recording the lost RLC PDU by reordering; reporting the status of the lost RLC PDU to the transmitting side; and requesting retransmission of the lost RLC PDU. If there is a lost RLC SDU, the sequential delivery of the NR RLC entity may include sequentially delivering only the RLC SDU before the lost RLC SDU to the upper layer; or, despite the presence of the lost RLC SDU, if a specified timer has expired, its sequential delivery may include sequentially delivering all RLC SDUs received before the timer is started to the upper layer; or, despite the presence of the lost RLC SDU, if a specified timer has expired, its sequential delivery may include sequentially delivering all RLC SDUs received so far to the upper layer. In addition, the NR RLC entity may process the RLC PDUs in the order in which they are received, regardless of the order of the sequence numbers, and transmit them to the NR PDCP entity in an out-of-order delivery manner. In case of received fragments, the NR RLC entity may reconstruct a complete RLC PDU from the fragments stored in the buffer or received later and transmit it to the NR PDCP entity. The NR RLC layer may not include the concatenation function, which may be performed by the NR MAC layer or replaced by the multiplexing function of the NR MAC layer.

[0056] In the above description, the out-of-order delivery of the NR RLC entity may indicate a function of directly transmitting the RLC SDUs received from the lower layer to the upper layer regardless of their order. If several RLC SDUs belonging to one original RLC SDU are received after segmentation, the out-of-order delivery of the NR RLC entity may include the reassembly and delivery of the RLC SDUs. Its out-of-order delivery may include storing the RLC SN or PDCP SN of the received RLC PDUs and sorting them to record the lost RLC PDUs.

[0057] NR MAC 4-15 or 4-30 can be connected to several NR RLC entities configured in one UE, and the main functions of NR MAC may include some of the following functions.

[0058] - Mapping function (mapping between logical channels and transport channels) - Multiplexing and demultiplexing functions (multiplexing / demultiplexing of MAC SDU) - Dispatch information reporting function (dispatch information reporting) - HARQ function (error correction through HARQ) - Priority handling between logical channels (priority handling between logical channels of a UE) - Priority handling between UEs (priority handling between UEs through dynamic scheduling) - MBMS service identification function (MBMS service identification) - Transmission format selection function (Transmission format selection) - Fill function (fill) The NR PHY 4-20 or 4-25 may combine upper layer data into OFDM symbols through channel coding and modulation and transmit them through a wireless channel, or may demodulate and channel decode OFDM symbols received through a wireless channel and forward the result to an upper layer.

[0059] Figure 5 The invention describes a cell reselection process performed by a UE in a next generation mobile communication system according to an embodiment of the present disclosure.

[0060] Reference Figure 5 , UE 5-01 can establish an RRC connection with the NR base station 5-02 and remain in RRC connected mode (RRC_CONNECTED) (5-05).

[0061] In step 5-10, the NR base station 5-02 may send an RRC release message to the UE 5-01. The RRC release message may be a message indicating the release of the RRC connection.

[0062] After receiving the RRC release message, at step 5-20, UE 5-01 may transition to RRC idle mode or RRC inactive mode. Specifically, if an RRC release message including Suspend Config information is received, UE 5-01 may transition to RRC inactive mode, otherwise it may transition to RRC idle mode.

[0063] At step 5-25, the UE 5-01 in the RRC idle mode or the RRC inactive mode may obtain basic system information. The basic system information may refer to a master information block (MIB) and a system information block 1 (SIB1).

[0064] In step 5-30, the UE 5-01 in RRC idle mode or RRC inactive mode may perform a cell selection procedure to camp on a cell suitable for NR. The cell on which the UE 5-01 has camped may be referred to as a serving cell.

[0065] In the present disclosure, if the conditions in the following Table 1 are met based on the 3GPP standard document "38.304: User Equipment (UE) procedures in Idle mode and RRC Inactive state", a suitable cell may be defined.

[0066] [Table 1]

[0067] For reference, if the following Equation 1 is satisfied, the UE 5-01 may determine that the cell selection criterion is satisfied.

[0068] [Equation 1] Srxlev>0 and Squal>0 in Srxlev = Q rxlevmeas - (Q rxlevmin + Q rxlevminoffset ) - P compensation -Qoffset temp , Squal = Q qualmeas - (Q qualmin + Q qualminoffset ) - Qoffset temp . For definitions of the parameters used here, please refer to the 3GPP standard document "38.304: User Equipment (UE) procedures in Idle mode and RRC Inactive state".

[0069] In step 5-35, the UE 5-01 in RRC idle mode or RRC inactive mode may obtain system information (e.g., SIB2, SIB3, SIB4, SIB5) containing cell reselection information from the serving cell 5-02 to perform a cell reselection evaluation process. SIB2 may include information / parameters that are generally applied to the UE to reselect NR intra-frequency, NR inter-frequency and RAT inter-frequency cells, as well as NR intra-frequency cell reselection information, but does not include information related to NR intra-frequency neighboring cells. For example, SIB2 may include a cell reselection priority configuration information for the serving NR frequency (the frequency to which the currently residing cell belongs). The cell reselection priority configuration information may refer to cellReselectionPriority and cellReselectionSubPriority. Specifically, cellReselectionPriority may have an integer value (e.g., an integer value in the range of 0 to 7), and cellReselectionSubPriority may have a decimal value (e.g., a decimal value among 0.2, 0.4, 0.6, 0.8). If both cellReselectionPriority and cellReselectionSubPriority are signaled, the UE can derive the cell reselection priority value by adding the two values. For reference, a larger cell reselection priority value means a higher priority. Specifically, the cell reselection configuration information broadcast in SIB2 can be as shown in Table 2 below.

[0070] [Table 2]

[0071]

[0072] SIB3 may include neighboring cell information / parameters for UE 5-01 to reselect an NR intra-frequency cell. For example, SIB3 may broadcast an NR intra-frequency cell list (intraFreqNeighCellList) to reselect an NR intra-frequency cell, or broadcast a cell list (intraFreqBlackCellList) that does not allow NR intra-frequency cell reselection. Specifically, SIB3 may broadcast the information in Table 3 below.

[0073] [Table 3]

[0074] SIB4 may include information / parameters for UE 5-01 to reselect an inter-NR frequency cell. For example, SIB4 may broadcast one or more inter-NR frequencies, and may include one cell reselection priority configuration information for each inter-NR frequency. The cell reselection priority configuration information for each inter-NR frequency refers to the above content (e.g., cellReselectionPriority and / or cellReselectionSubPriority mapped to each inter-NR frequency), but has the characteristic of optionally broadcasting one cell reselection priority configuration information for each frequency. Specifically, the information in Table 4 below may be broadcast in SIB4.

[0075] [Table 4]

[0076]

[0077] SIB5 may include information / parameters for UE to reselect inter-RAT frequency cells. For example, SIB5 may broadcast one or more EUTRA frequencies and may include a cell reselection priority configuration information for each EUTRA frequency. The cell reselection priority configuration information for each EUTRA frequency may refer to the above content (e.g., cellReselectionPriority and / or cellReselectionSubPriority mapped to each EUTRA frequency), but has the feature of optionally broadcasting a cell reselection priority configuration information for each EURA frequency. Specifically, the information in Table 5 below may be broadcast in SIB5.

[0078] [Table 5]

[0079] The UE 5-01 in the RRC idle mode or the RRC inactive mode may perform a cell reselection evaluation process. The cell reselection evaluation process may refer to the following series of processes: determining a reselection priority (reselection priority processing), performing frequency measurement by applying a measurement rule for cell reselection according to the determined reselection priority, and evaluating the cell reselection criteria accordingly to reselect a cell.

[0080] In step 5-40, the UE 5-01 in RRC idle mode or RRC inactive mode may derive the reselection priority based on the system information received in step 5-25. The UE may determine the reselection priority only for the frequency for which the cell reselection priority value is broadcast via the system information. Regarding the cell reselection priority value mapped to the NR frequency to which the currently camped serving cell belongs, the UE 5-01 according to the present disclosure may determine whether each inter-NR frequency or inter-RAT frequency has the same cell reselection priority as the NR frequency to which the serving cell belongs, whether it has a higher cell reselection priority than the NR frequency to which the serving cell belongs, or whether it has a lower cell reselection priority than the NR frequency to which the serving cell belongs. For example, in the system information obtained in step 5-25, if the cell reselection priority value mapped to the NR frequency where the serving cell is currently residing is 3, the cell reselection priority value of inter-NR frequency 1 is 2, the cell reselection priority value of inter-NR frequency 2 is 3, the cell reselection priority value of inter-NR frequency 3 is 4, and the cell reselection priority value of EUTRA frequency 1 is 2, then UE 5-01 can determine the cell reselection priorities of inter-NR frequency 1 and EUTRA frequency 1 as lower reselection priorities, determine the cell reselection of inter-NR frequency 2 as equal reselection priorities, and determine the cell reselection priority of inter-NR frequency 3 as a higher reselection priority.

[0081] At step 5-45, UE 5-01 in RRC idle mode or RRC inactive mode may perform frequency measurement for cell reselection. At this time, in order to minimize battery consumption, UE 5-01 may perform frequency measurement by using the following measurement rules according to the cell reselection priority determined at step 5-40.

[0082] If the following condition 1 is met, UE 5-01 may not perform NR intra-frequency measurement. Otherwise (for example, if the following condition 1 is not met), UE 5-01 performs NR intra-frequency measurement.

[0083] ■Condition 1: The reception level (Srxlev) of the serving cell is greater than the threshold SIntraSearchP and the reception quality (Squal) of the serving cell is greater than the threshold SIntraSearchQ (the serving cell satisfies Srxlev>SIntraSearchP and Squal>SIntralSearchQ).

[0084] The UE may perform measurements on an inter-NR frequency or an inter-RAT frequency having a higher reselection priority than the NR frequency of the current serving cell according to the 3GPP TS 38.133 standard.

[0085] For an inter-NR frequency whose reselection priority is lower than or equal to the NR frequency of the current serving cell and an inter-RAT frequency whose reselection priority is lower than the NR frequency of the current serving cell, if the following condition 2 is met, the UE 5-01 may not perform measurement. Otherwise (for example, if the following condition 2 is not met), the UE measures a cell of an inter-NR frequency whose reselection priority is lower than or equal to the NR frequency or measures a cell of an inter-RAT frequency whose reselection priority is lower than the NR frequency.

[0086] ■Condition 2: The reception level (Srxlev) of the serving cell is greater than the threshold value SnonIntraSearchP, and the reception quality (Squal) of the serving cell is greater than the threshold value SnonIntraSearchQ (the serving cell satisfies Srxlev>SnonIntraSearchP and Squal>SnonIntraSearchQ).

[0087] For reference, the above thresholds (SIntraSearchP, SIntraSearchQ, SnonTrintraSearchPSnonintraSearchQ) may be broadcast via the system information obtained in step 5-25.

[0088] In step 5-50, for reselection, the UE 5-01 in RRC idle mode or RRC inactive state can determine a cell that meets the cell reselection criteria based on the measurement value obtained in step 5-45. The cell reselection criteria can apply different criteria according to the cell reselection priority. If multiple cells that meet the cell reselection criteria have different cell reselection priorities, reselection of a frequency / RAT cell with a higher cell reselection priority should take precedence over reselection of a frequency / RAT cell with a lower priority (if multiple cells of different priorities meet the cell reselection criteria, cell reselection to a higher priority RAT / frequency should take precedence over a lower priority RAT / frequency). Specifically, for the reselection criteria of an inter-frequency / inter-RAT cell with a priority higher than the current serving cell frequency, the UE operates as follows.

[0089] First operation: ■When the threshold Thresh Serving,LowQ broadcast in SIB2 and 1 second has passed since UE 5-01 camped on the current serving cell, if at a specific time T reselectionRAT During this period, the signal quality (Squal) of the inter-frequency / inter-RAT cell is greater than the threshold Thresh X,HighQ (In the time interval T reselectionRAT During this period, Squal>Thresh X,HighQ ), the UE reselects the corresponding inter-frequency / inter-RAT cell.

[0090] Second operation: ■If UE 5-01 cannot perform the first operation, perform the second operation.

[0091] ■ If 1 second has passed since UE 5-01 camped on the current serving cell, and at a specific time T reselectionRAT During this period, the reception level (Srxlev) of the inter-frequency / inter-RAT cell is greater than the threshold Thresh X,HighP (In the time interval T reselectionRAT During this period, Srxlev>Thresh X,HighP ), UE 5-01 reselects the corresponding inter-frequency / inter-RAT cell.

[0092] Here, the UE 5-01 receives the signal based on the information contained in the SIB4 broadcasted from the serving cell, such as the signal quality (Squal), the reception level (Srxlev), the threshold (Thresh X,HighQ , Thresh X,HighP ) and T reselectionRAT value, performing the first operation or the second operation on the inter-frequency cell, and based on the information contained in the SIB5 broadcasted from the serving cell, such as the signal quality (Squal), the reception level (Srxlev), the threshold (Threh X,HighQ , Thresh X,HighP ) and T reselectionRAT value, perform the first operation or the second operation on the inter-RAT cell. For example, SIB4 includes Q qualmin Value or Q rxlevmin value, and based on this derive the signal quality (Squal) or reception level (Srxlev) of the inter-frequency cell. If multiple cells of the NR frequency have high cell reselection priority, the UE5-01 may reselect the highest ranked cell among the cells that meet the reselection criteria for intra-frequency / inter-frequency cells with the same priority as the frequency of the current serving cell described below.

[0093] In addition, the operation of the reselection criteria of UE 5-01 for an intra-frequency / inter-frequency cell having the same frequency priority as the current serving cell is as follows.

[0094] Third operation: ■ If the signal quality (Squal) and reception level (Srxlev) of the intra-frequency / inter-frequency cells are greater than 0, a cell-specific ranking is derived based on the measurements (RSRP, Reference Signal Received Power) (the UE shall rank all cells that satisfy the cell selection criterion S). The ranking of the serving cell and neighboring cells is calculated using Equation 2 below.

[0095] [Equation 2] R s =Q meas,s+Q hyst R n =Q meas,n -Q offset Here, Q meas,s is the RSRP measurement value of the serving cell, Q mea,n is the RSRP measurement value of the neighboring cell, Q hyst is the hysteresis value between serving cells, Q offset is the offset between the serving cell and the neighboring cell. SIB2 contains Q which is usually used for intra-frequency / inter-frequency cell reselection. hyst In the case of intra-frequency cell reselection, each cell sends Q offset , applies only to the indicated cell and is included in SIB3. In case of inter-frequency cell reselection, each cell signals Q offset , is only applied to the indicated cell and is included in SIB4. In the case that the rank of the neighboring cell obtained from the above equation 2 is greater than the rank of the serving cell (Rn>Rs), the best cell among the neighboring cells is reselected.

[0096] In addition, the operation of the UE's reselection criteria for inter-frequency / inter-RAT cells with a priority lower than the current serving cell frequency is as follows.

[0097] Fourth operation: ■When the threshold Thresh Serving,LowQ Broadcast in SIB2, and after UE 5-01 camps on the current serving cell for 1 second, if the signal quality (Squal) of the current serving cell is lower than the threshold Thresh Serving,LowQ (Squal<Thresh Serving,LowQ ), and at a specific time T reselectionRAT During this period, the signal quality (Squal) of the inter-frequency / inter-RAT cell is higher than the threshold Thresh X,LowQ (In the time interval P reselectional During this period, Squal>Thresh X,LowQ ), the UE reselects to the corresponding inter-frequency / inter-RAT cell.

[0098] Fifth operation: ■If the UE is unable to perform the fourth operation, perform the fifth operation.

[0099] ■ If 1 second has passed since the UE camped on the current serving cell and the reception level (Srxlev) of the current serving cell is lower than the threshold Thresh Serving，LowP (Srxlev <Thresh Serving,LowP ), and at a specific time T reselectionRATDuring this period, the reception level (Srxlev) of the inter-frequency / inter-RAT cell is higher than the threshold Thresh X,LowQ (In the time interval T reselectionRAT During this period, Srxlev>Thresh X,LowP ). UE 5-01 will reselect the corresponding inter-frequency / inter-RAT cell.

[0100] The fourth or fifth operation of the inter-frequency cell of UE 5-01 is based on a threshold value (Thresh Serving,LowQ , Thresh Serving,LowP ) and the signal quality (Squal), reception level (Srxlev), threshold (Thresh X,LowQ , Thresh X,LowP ) and T reselectionRAT The fourth or fifth operation of the inter-RAT cell of the UE is based on the threshold value (Thresh Serving,LowQ , Thresh Serving,LowP ) and the signal quality (Squal), reception level (Srxlev), threshold (Thresh X,LowQ , Thresh X,LowP ) and T reselectionRAT For example, SIB4 includes Q qualmin Value or Q rxlevmin value, and UE 5-01 can derive the signal quality (Squal) or reception level (Srxlev) of the inter-frequency cell based on this. If there are multiple cells with NR frequencies that meet high cell reselection priorities, the terminal 5-01 can reselect the highest-ranked cell among the cells that meet the reselection criteria for intra-frequency / inter-frequency cells with the same priority as the frequency of the current serving cell described below. Here, if a candidate cell that meets the above conditions is derived from a frequency with a priority higher or lower than the frequency of the current serving cell, the UE 5-01 can reselect the derived candidate cell as the best cell (strongest cell).

[0101] In step 5-55, before finally reselecting the candidate target cell, the UE 5-01 in RRC idle mode or RRC inactive state receives system information (e.g., MIB or SIB1) broadcast by the candidate target cell, and determines whether the reception level (Srxlev) and reception quality (Squal) of the candidate target cell meet the cell selection criterion (Srxlev>0 and Squal>0) called the S criterion (Equation 1) based on the received system information. If Equation 1 is met and the candidate target cell is suitable, the UE 5-01 can reselect the candidate target cell.

[0102] Figure 6 is a diagram depicting a cell reselection procedure performed by an air UE in a next generation mobile communication system according to an embodiment of the present disclosure.

[0103] The UE according to an embodiment of the present disclosure may be referred to as an aerial UE. For example, the aerial UE may be a UE with an unmanned aerial vehicle (UAV) function, or may represent a drone. In other words, the aerial UE may receive UAV services while flying at a specific altitude.

[0104] Reference Figure 6 , the airborne UE 6-01 can establish an RRC connection with the NR base station 6-02 and remain in the RRC connected mode (RRC_CONNECTED) (6-05).

[0105] In step 6-10, the over-the-air UE 6-01 may send a UE capability information message to the NR base station 6-02. This message may include the following information.

[0106] - An indicator indicating whether the airborne UE can apply the cell reselection priority for the airborne UE broadcasted in the system information in RRC idle mode (RRC_IDLE) or RRC inactive mode (RRC_INACTIVE). For example, the indicator may be referred to as, but not limited to, airborne UE information for cell reselection.

[0107] In step 6-15, the NR base station 6-02 may send an RRC connection release message (RRC release message) to the airborne UE 6-01.

[0108] Upon receiving the RRC release message, in step 6-20, the airborne UE 6-01 may transition to RRC idle mode or RRC inactive mode. Specifically, upon receiving the RRC release message including the suspension configuration information, the airborne UE 6-01 may transition to RRC inactive mode, otherwise it may transition to RRC idle mode.

[0109] At step 6-25, the over-the-air UE 6-01 in the RRC idle mode or the RRC inactive mode may obtain basic system information. The basic system information may indicate a master information block (MIB) and a system information block 1 (SIB1).

[0110] In step 6-30, the airborne UE 6-01 in RRC idle mode or RRC inactive mode may perform a cell selection procedure to camp on a cell suitable for the NR.

[0111] In step 6-35, the UE 6-01 in RRC idle mode or RRC inactive mode may obtain system information (e.g., SIB2, SIB3, SIB4, SIB5, new SIB) containing cell reselection information from the serving cell 6-02 to perform a cell reselection evaluation process. According to an embodiment of the present disclosure, it is recommended that the serving cell broadcast one or two cell reselection priority (referred to as CRP) values ​​per frequency. Specifically, - At least one of the first CRP (legacy CRP) or the second CRP (CRP for airborne UEs) of the serving frequency may be broadcast in SIB2.

[0112] - At least one of the first CRP (legacy CRP) or the second CRP (CRP for over-the-air UEs) for each inter-NR frequency may be broadcast in SIB4.

[0113] - At least one of the first CRP (legacy CRP) or the second CRP (CRP for airborne UEs) for each E-UTRAN frequency may be broadcast in SIB5.

[0114] - If the second CRP (CRP for airborne UEs) is not broadcast in the above system information, the second CRP (CRP for airborne UEs) for each frequency may be broadcast in a new SIB.

[0115] -CRP may indicate at least one of a cell reselection priority IE (information element) or a cell reselection sub-priority IE. As described in the above embodiments, the cell reselection priority IE may store an integer value (e.g., an integer value from 0 to 7), and the cell reselection sub-priority IE may store a decimal value (e.g., a decimal value among 0.2, 0.4, 0.6, 0.8). If only one of the two IEs is signaled, the UE 6-01 may derive the cell reselection priority value from the signaled value, and if both IEs are signaled, the UE may derive the cell reselection priority value by adding the two signaled values.

[0116] The over-the-air UE 6-01 in RRC idle mode or RRC inactive mode may perform a cell reselection evaluation procedure. The cell reselection evaluation procedure may refer to the following series of processes: determining a reselection priority (reselection priority processing), performing frequency measurement according to the determined reselection priority by applying a measurement rule for cell reselection, and evaluating the cell reselection criteria accordingly to reselect a cell.

[0117] In step 6-40, an airborne UE 6-01 in RRC idle mode or RRC inactive mode may derive a reselection priority based on the system information received in step 6-25. UE 6-01 may determine the reselection priority only for the frequency in which the cell reselection priority value is broadcast in the system information. It is suggested that the UE 6-01 according to the present disclosure determines the reselection priority by applying the second CRP in the case of broadcasting the second CRP for each frequency, or determines the reselection priority by applying the first CRP for each frequency without broadcasting the second CRP. Specifically, if the second CRP is broadcast only for a specific frequency, or both the first CRP and the second CRP are broadcast, the UE 6-01 may apply the second CRP to determine the reselection priority. If the first CRP is broadcast only for a specific frequency, the UE 6-01 may apply it to determine the reselection priority. The method for UE 6-01 to derive a frequency-specific reselection priority may follow the above-mentioned embodiment. An advantage of the present disclosure is that interference in a downlink or uplink or a cell load may be controlled by allowing an airborne UE 6-01 to apply a separate CRP at a specific frequency.

[0118] In step 6-45, the airborne UE 6-01 in RRC idle mode or RRC inactive mode may perform frequency measurement for cell reselection. At this time, in order to minimize battery consumption, the UE 6-01 may perform frequency measurement according to the cell reselection priority determined in step 6-40 by using the measurement rule of the above embodiment. For example, the measurement rule and measurement operation described in step 5-45 may be applied in step 6-45.

[0119] In step 6-50, the aerial UE 6-01 in RRC idle mode or RRC inactive state may determine a cell that meets the cell reselection criteria based on the measurement value for cell reselection obtained in step 6-45. This may follow the above-described embodiment. For example, the cell reselection operation described in step 5-50 may be applied in step 6-50. For reference, in the present disclosure, a list of cells that the aerial UE 6-01 may reselect (e.g., a PCI list for cell reselection of the aerial UE) may be broadcast, and only cells belonging to the broadcasted cell list may be reselected. Alternatively, a list of cells that the aerial UE 6-01 may not reselect may be broadcast, and only cells that do not belong to the broadcasted cell list may be reselected. For reference, the parameters applied to Equation 2 (e.g., Q offset ) can be broadcasted separately in system information, and the UE can apply it to perform cell ranking (indicated in Equation 2).

[0120] At step 6-55, before finally reselecting the candidate target cell, the over-the-air UE 6-01 in RRC idle mode or RRC inactive state receives system information (e.g., MIB or SIB1) broadcasted by the candidate target cell, and determines whether the reception level (Srxlev) and reception quality (Squal) of the candidate target cell meet a cell selection criterion (Srxlev>0 and Squal>0) called the S criterion (Equation 1) based on the received system information. If Equation 1 is met and the candidate target cell is suitable, the UE 6-01 may reselect the candidate target cell.

[0121] Figure 6 The example omits the Figure 5 The same configuration as described in the example, so Figure 6 In the example with Figure 5 For a description of the corresponding process and messages, please refer to Figure 5 Description in .

[0122] Figure 7 is a diagram depicting a cell reselection procedure performed by an air UE in a next generation mobile communication system according to an embodiment of the present disclosure.

[0123] The UE according to an embodiment of the present disclosure may be referred to as an aerial UE. For example, the aerial UE may be a UE with an unmanned aerial vehicle (UAV) function, or may represent a drone. The aerial UE may receive UAV services while flying at a specific altitude.

[0124] Reference Figure 7 , the airborne UE 7-01 can establish an RRC connection with the NR base station 7-02 and remain in the RRC connected mode (RRC_CONNECTED) (7-05).

[0125] In step 7-10, the over-the-air UE 7-01 may send a UE capability information message to the NR base station 7-02. This message may include the following information.

[0126] - An indicator indicating whether the airborne UE 7-02 can apply the cell reselection priority for the airborne UE broadcasted in the system information in RRC idle mode (RRC_IDLE) or RRC inactive mode (RRC_INACTIVE). For example, the indicator may be called but not limited to airborne UE information for cell reselection.

[0127] In step 7-15, the NR base station 7-02 may send an RRC connection release message (RRC release message) to the airborne UE 7-01.

[0128] Upon receiving the RRC release message, in step 7-20, the airborne UE 7-01 can transition to the RRC idle mode or the RRC inactive mode. Specifically, when receiving the RRC release message including the suspension configuration information, the airborne UE 7-01 can transition to the RRC inactive mode, otherwise it can transition to the RRC idle mode.

[0129] In step 7-25, the over-the-air UE 7-01 in the RRC idle mode or the RRC inactive mode may obtain basic system information. The basic system information may indicate a master information block (MIB) and a system information block 1 (SIB1).

[0130] In step 7-30, the airborne UE 7-01 in RRC idle mode or RRC inactive mode may perform a cell selection procedure to camp on a cell suitable for the NR.

[0131] In step 7-35, the UE 7-01 in RRC idle mode or RRC inactive mode can obtain system information (e.g., SIB2, SIB3, SIB4, SIB5, new SIB) containing cell reselection information from the serving cell 7-02 to perform a cell reselection evaluation process. It is recommended that the serving cell according to an embodiment of the present disclosure broadcast one or two cell reselection priority (referred to as CRP) values ​​per frequency. Specifically, - At least one of the first CRP (legacy CRP) or the second CRP (CRP for airborne UEs) of the serving frequency may be broadcast in SIB2.

[0132] - At least one of the first CRP (legacy CRP) or the second CRP (CRP for over-the-air UEs) for each inter-NR frequency may be broadcast in SIB4.

[0133] - At least one of the first CRP (legacy CRP) or the second CRP (CRP for airborne UEs) for each E-UTRAN frequency may be broadcast in SIB5.

[0134] - If the second CRP (CRP for airborne UEs) is not broadcast in the above system information, the second CRP (CRP for airborne UEs) for each frequency may be broadcast in a new SIB.

[0135] The CRP may indicate at least one of a cell reselection priority IE (information element) or a cell reselection sub-priority IE. As described in the above embodiments, the cell reselection priority IE may store an integer value (e.g., an integer value from 0 to 7), and the cell reselection sub-priority IE may store a decimal value (e.g., a decimal value among 0.2, 0.4, 0.6, 0.8). If only one of the two IEs is signaled, the UE 7-01 may derive the cell reselection priority value from the signaled value, and if both IEs are signaled, the UE may derive the cell reselection priority value by adding the two signaled values.

[0136] The over-the-air UE 7-01 in RRC idle mode or RRC inactive mode may perform a cell reselection evaluation process. The cell reselection evaluation process may refer to the following series of processes: determining a reselection priority (reselection priority processing), performing frequency measurement according to the determined reselection priority by applying a measurement rule for cell reselection, and evaluating the cell reselection criteria accordingly to reselect a cell.

[0137] In step 7-40, an airborne UE 7-01 in RRC idle mode or RRC inactive mode may derive a reselection priority based on the system information received in step 7-25. UE 7-01 may determine the reselection priority only for the frequency in which the cell reselection priority value is broadcast in the system information. It is recommended that if a second CRP is broadcast on at least one frequency, UE 7-01 only determines the reselection priority for the frequency in which the second CRP is broadcast. That is, UE 7-01 has the characteristic of not deriving a reselection priority on a frequency in which only the first CRP is broadcast. Since the reselection priority is derived based on the service frequency, if the second CRP is not broadcast for the service frequency, UE 7-01 may derive the reselection priority by applying the first CRP, or may determine the service frequency as the lowest priority and derive the reselection priority for the remaining frequencies. The method by which UE 7-01 derives a frequency-specific reselection priority may follow the above-described embodiment. An advantage of the present disclosure is that network operators may effectively manage frequencies by allowing airborne UE 7-01 to apply only the second CRP.

[0138] In step 7-45, the airborne UE 7-01 in RRC idle mode or RRC inactive mode may perform frequency measurement for cell reselection. At this time, in order to minimize battery consumption, the UE 7-01 may perform frequency measurement according to the cell reselection priority determined in step 7-40 by using the measurement rules of the above embodiment. For example, the measurement rules and measurement operations described in step 5-45 may be applied in step 7-45.

[0139] In step 7-50, the airborne UE 7-01 in RRC idle mode or RRC inactive state may determine a cell that meets the cell reselection criteria based on the measurement value for cell reselection obtained in step 7-45. This may follow the above-described embodiment. For example, the cell reselection operation described in step 5-50 may be applied in step 7-50. For reference, in the present disclosure, a list of cells that the airborne UE 7-01 may reselect (e.g., a PCI list for cell reselection of the airborne UE) may be broadcast, and only cells belonging to the broadcasted cell list may be reselected. Alternatively, a list of cells that the airborne UE 7-01 may not reselect may be broadcast, and only cells that do not belong to the broadcasted cell list may be reselected. For reference, the parameters (e.g., Q) applied to equation 2 offset ) can be broadcasted separately in system information, and UE 7-01 can apply it to perform cell ranking (indicating equation 2).

[0140] In step 7-55, before finally reselecting the candidate target cell, the over-the-air UE 7-01 in RRC idle mode or RRC inactive state receives system information (e.g., MIB or SIB1) broadcasted by the candidate target cell, and determines whether the reception level (Srxlev) and reception quality (Squal) of the candidate target cell meet the cell selection criterion (Srxlev>0 and Squal>0) called the S criterion (Equation 1) based on the received system information. If Equation 1 is met and the candidate target cell is suitable, the UE 7-01 can reselect the candidate target cell.

[0141] Figure 7 The example omits the Figure 5 or Figure 6 The same configuration as described in the example, therefore, for Figure 7 In the example with Figure 5 or Figure 6 For a description of the corresponding process and messages, please refer to Figure 5 or Figure 6 Description in .

[0142] Figure 8 is a diagram depicting a cell reselection procedure performed by an air UE in a next generation mobile communication system according to an embodiment of the present disclosure.

[0143] The UE according to an embodiment of the present disclosure may be referred to as an aerial UE. For example, the aerial UE may be a UE with an unmanned aerial vehicle (UAV) function, or may represent a drone. In other words, the aerial UE may receive UAV services while flying at a specific altitude.

[0144] Reference Figure 8 , the airborne UE 8-01 can establish an RRC connection with the NR base station 8-02 and remain in the RRC connected mode (RRC_CONNECTED) (8-05).

[0145] In step 8-10, the over-the-air UE 8-01 may send a UE capability information message to the NR base station 8-02. This message may include the following information.

[0146] - An indicator indicating whether the airborne UE can apply the cell reselection priority for the airborne UE broadcasted in the system information in RRC idle mode (RRC_IDLE) or RRC inactive mode (RRC_INACTIVE). The indicator may be referred to as, but not limited to, airborne UE information for cell reselection.

[0147] In step 8-15, the NR base station 8-02 may send an RRC connection release message (RRC release message) to the airborne UE 8-01.

[0148] Upon receiving the RRC release message, in step 8-20, the airborne UE 8-01 can transition to the RRC idle mode or the RRC inactive mode. Specifically, when receiving the RRC release message including the suspension configuration information, the airborne UE 8-01 can transition to the RRC inactive mode, otherwise it can transition to the RRC idle mode.

[0149] In step 8-25, the over-the-air UE 8-01 in the RRC idle mode or the RRC inactive mode may obtain basic system information. The basic system information may indicate a master information block (MIB) and a system information block 1 (SIB1).

[0150] In step 8-30, the airborne UE 8-01 in RRC idle mode or RRC inactive mode may perform a cell selection procedure to camp on a cell suitable for the NR.

[0151] In step 8-35, the UE 8-01 in RRC idle mode or RRC inactive mode may obtain system information (e.g., SIB2, SIB3, SIB4, SIB5, new SIB) containing cell reselection information from the serving cell 8-02 to perform a cell reselection evaluation process. It is recommended that the serving cell according to an embodiment of the present disclosure broadcast one or two cell reselection priority (referred to as CRP) values ​​per frequency. Specifically, - At least one of the first CRP (legacy CRP) or the second CRP (CRP for airborne UEs) of the serving frequency may be broadcast in SIB2.

[0152] - At least one of the first CRP (legacy CRP) or the second CRP (CRP for over-the-air UEs) for each inter-NR frequency may be broadcast in SIB4.

[0153] - At least one of the first CRP (legacy CRP) or the second CRP (CRP for airborne UEs) for each E-UTRAN frequency may be broadcast in SIB5.

[0154] - If the second CRP (CRP for airborne UEs) is not broadcast in the above system information, the second CRP (CRP for airborne UEs) for each frequency may be broadcast in a new SIB.

[0155] - CRP may indicate at least one of a cell reselection priority IE (information element) or a cell reselection sub-priority IE. As described in the above embodiments, the cell reselection priority IE may store an integer value (e.g., an integer value from 0 to 7), and the cell reselection sub-priority IE may store a decimal value (e.g., a decimal value among 0.2, 0.4, 0.6, 0.8). If only one of the two IEs is signaled, the UE 8-01 may derive the cell reselection priority value from the signaled value, and if both IEs are signaled, the UE may derive the cell reselection priority value by adding the two signaled values.

[0156] The over-the-air UE 8-01 in RRC idle mode or RRC inactive mode may perform a cell reselection evaluation procedure. The cell reselection evaluation procedure may refer to the following series of processes: determining a reselection priority (reselection priority processing), performing frequency measurement according to the determined reselection priority by applying a measurement rule for cell reselection, and evaluating the cell reselection criteria accordingly to reselect a cell.

[0157] In step 8-40, an airborne UE 8-01 in RRC idle mode or RRC inactive mode may derive a reselection priority based on the system information received in step 8-25. UE 8-01 may determine the reselection priority only for the frequency at which the cell reselection priority value is broadcast in the system information. According to the present disclosure, UE 8-01 has the characteristic that the frequency at which the second CRP is broadcast is always determined to have a higher reselection priority than the frequency at which only the first CRP is broadcast. For the frequency at which the second CRP is broadcast, the reselection priority may be derived based on the second CRP value; for the frequency at which only the first CRP is broadcast, the reselection priority may be derived based on the first CRP value. For example, operations 5-40, 6-40, and 7-40, etc. may be referred to. The method by which UE 8-01 derives frequency-specific reselection priorities may follow the above-mentioned embodiments. An advantage of the present disclosure is that it may help operators operate by allowing cell reselection to be performed first on a frequency that supports the second CRP.

[0158] In step 8-45, the airborne UE 8-01 in RRC idle mode or RRC inactive mode may perform frequency measurement for cell reselection. At this time, in order to minimize battery consumption, the UE 8-01 may perform frequency measurement according to the cell reselection priority determined in step 8-40 by using the measurement rules of the above embodiment. For example, the measurement rules and measurement operations described in step 5-45 may be applied in step 8-45.

[0159] In step 8-50, the airborne UE 8-01 in RRC idle mode or RRC inactive state can determine the cell that meets the cell reselection criteria based on the measurement value for cell reselection obtained in step 8-45. This can follow the above embodiment. For example, the measurement rules and measurement operations described in step 5-45 can be applied in step 8-45.

[0160] In step 8-55, before finally reselecting the candidate target cell, the over-the-air UE 8-01 in RRC idle mode or RRC inactive state receives system information (e.g., MIB or SIB1) broadcasted by the candidate target cell, and determines whether the reception level (Srxlev) and reception quality (Squal) of the candidate target cell meet the cell selection criterion (Srxlev>0 and Squal>0) referred to as the S criterion (Equation 1) based on the received system information. If Equation 1 is met and the candidate target cell is suitable, the UE 8-01 can reselect the candidate target cell.

[0161] exist Figure 8 The example omits the Figure 5 , Figure 6 or Figure 7 The same configuration as described in the example, so for Figure 8 In the example with Figure 5 , Figure 6 or Figure 7 For a description of the corresponding processes and messages, please refer to Figure 5 , Figure 6 or Figure 7 Description in .

[0162] Fig. 9 is a diagram depicting a cell reselection procedure performed by an air UE in a next generation mobile communication system according to an embodiment of the present disclosure.

[0163] The UE according to an embodiment of the present disclosure may be referred to as an aerial UE. For example, the aerial UE may be a UE with an unmanned aerial vehicle (UAV) function, or may represent a drone. In other words, the aerial UE may receive UAV services while flying at a specific altitude.

[0164] Reference Fig. 9 , the airborne UE 9-01 can establish an RRC connection with the NR base station 9-02 and remain in the RRC connected mode (RRC_CONNECTED) (9-05).

[0165] In step 9-10, the airborne UE 9-01 may send a UE capability information message to the NR base station 9-02. This message may include the following information.

[0166] - An indicator indicating whether the airborne UE can apply the cell reselection priority for the airborne UE broadcasted in the system information in RRC idle mode (RRC_IDLE) or RRC inactive mode (RRC_INACTIVE). The indicator may be referred to as, but not limited to, airborne UE information for cell reselection.

[0167] In step 9-15, the NR base station 9-02 may send an RRC connection release message (RRC release message) to the airborne UE 9-01.

[0168] Upon receiving the RRC release message, in step 9-20, the airborne UE 9-01 can switch to the RRC idle mode or the RRC inactive mode. Specifically, when receiving the RRC release message including the suspension configuration information, the airborne UE 9-01 can switch to the RRC inactive mode, otherwise it can switch to the RRC idle mode.

[0169] In step 9-25, the over-the-air UE 9-01 in the RRC idle mode or the RRC inactive mode may obtain basic system information. The basic system information may indicate a master information block (MIB) and a system information block 1 (SIB1).

[0170] In step 9-30, the airborne UE 9-01 in RRC idle mode or RRC inactive mode may perform a cell selection procedure to camp on a cell suitable for the NR.

[0171] In step 9-35, the UE 9-01 in the RRC idle mode or the RRC inactive mode may obtain system information (e.g., SIB2, SIB3, SIB4, SIB5, new SIB) containing cell reselection information from the serving cell 9-02 to perform a cell reselection evaluation process. It is recommended that the serving cell according to an embodiment of the present disclosure broadcast two cell reselection priority (referred to as CRP) values ​​per frequency. Specifically, - At least one of the first CRP (legacy CRP) or the second CRP (CRP for airborne UEs) of the serving frequency may be broadcast in SIB2.

[0172] - At least one of the first CRP (legacy CRP) or the second CRP (CRP for over-the-air UEs) for each inter-NR frequency may be broadcast in SIB4.

[0173] - At least one of the first CRP (legacy CRP) or the second CRP (CRP for airborne UEs) for each E-UTRAN frequency may be broadcast in SIB5.

[0174] - If the second CRP (CRP for over-the-air UEs) is not broadcast in the above system information, the second CRP for each frequency may be broadcast in a new SIB.

[0175] - CRP may indicate at least one of a cell reselection priority IE (information element) or a cell reselection sub-priority IE. As described in the above embodiments, the cell reselection priority IE may store an integer value (e.g., an integer value from 0 to 7), and the cell reselection sub-priority IE may store a decimal value (e.g., a decimal value among 0.2, 0.4, 0.6, 0.8). If only one of the two IEs is signaled, the UE may derive the cell reselection priority value from the signaled value, and if both IEs are signaled, the UE may derive the cell reselection priority value by adding the two signaled values.

[0176] Furthermore, in the present disclosure, a height threshold that is universally applicable regardless of frequency or a height threshold for a specific frequency may be broadcast in system information.

[0177] The over-the-air UE 9-01 in RRC idle mode or RRC inactive mode may perform a cell reselection evaluation process. The cell reselection evaluation process may refer to the following series of processes: determining a reselection priority (reselection priority processing), performing frequency measurement according to the determined reselection priority by applying a measurement rule for cell reselection, and evaluating the cell reselection criteria accordingly to reselect a cell.

[0178] In step 9-40, an airborne UE 9-01 in RRC idle mode or RRC inactive mode may derive a reselection priority based on the system information received in step 9-25. UE 9-01 may determine the reselection priority only for the frequency at which the cell reselection priority value is broadcast in the system information. If the UE is flying at or above a specific altitude threshold broadcast in the system information, the UE 9-01 according to the present disclosure may determine the reselection priority by applying a second CRP associated with the specific altitude threshold (a second CRP associated with an altitude 1 threshold) to at least one of the above-mentioned embodiments. If the UE is flying at or below the altitude threshold broadcast in the system information, the reselection priority may be determined according to the fifth embodiment. For reference, since the interference caused by airborne UEs is different at different flight altitudes, it is effective for network management to determine the reselection priority based on the flight altitude.

[0179] In step 9-45, the airborne UE 9-01 in RRC idle mode or RRC inactive mode may perform frequency measurement for cell reselection. At this time, in order to minimize battery consumption, the UE 9-01 may perform frequency measurement according to the cell reselection priority determined in step 9-40 by using the measurement rules of the above embodiment. For example, the measurement rules and measurement operations described in step 5-45 may be applied in step 9-45.

[0180] In step 9-50, the airborne UE 9-01 in RRC idle mode or RRC inactive state can determine the cell that meets the cell reselection criteria based on the measurement value for cell reselection obtained in step 9-45. This can follow the above embodiment. For example, the cell reselection operation described in step 5-50 can be applied in step 9-50.

[0181] In step 9-55, before finally reselecting the candidate target cell, the over-the-air UE 9-01 in RRC idle mode or RRC inactive state receives system information (e.g., MIB or SIB1) broadcasted by the candidate target cell, and determines whether the reception level (Srxlev) and reception quality (Squal) of the candidate target cell meet the cell selection criterion (Srxlev>0 and Squal>0) called the S criterion (Equation 1) based on the received system information. If Equation 1 is met and the candidate target cell is suitable, the UE 9-01 can reselect the candidate target cell.

[0182] exist Fig. 9 The example omits the Figure 5 , Figure 6 , Figure 7 or Figure 8 The same configuration as described in the example, therefore, for Fig. 9 In the example with Figure 5 , Figure 6 , Figure 7 or Figure 8 For a description of the corresponding processes and messages, please refer to Figure 5 , Figure 6 , Figure 7 or Figure 8 Description in .

[0183] Fig.10 is a diagram depicting a cell reselection procedure performed by an air UE in a next generation mobile communication system according to an embodiment of the present disclosure.

[0184] The UE according to an embodiment of the present disclosure may be referred to as an aerial UE. For example, the aerial UE may be a UE with an unmanned aerial vehicle (UAV) function, or may represent a drone. In other words, the aerial UE may receive UAV services while flying at a specific altitude.

[0185] Reference Fig.10 , the UE 10-01 in the air can establish an RRC connection with the NR base station 10-02 and remain in the RRC connected mode (RRC_CONNECTED) (10-05).

[0186] In step 10-10, the over-the-air UE 10-01 may send a UE capability information message to the NR base station 10-02. This message may include the following information.

[0187] - An indicator indicating whether the airborne UE can apply the cell reselection priority for the airborne UE broadcasted in the system information in RRC idle mode (RRC_IDLE) or RRC inactive mode (RRC_INACTIVE). The indicator may be referred to as, but not limited to, airborne UE information for cell reselection.

[0188] In step 10-15, the NR base station 10-02 may send an RRC connection release message (RRC release message) to the airborne UE 10-01.

[0189] Upon receiving the RRC release message, in step 10-20, the airborne UE 10-01 may transition to the RRC idle mode or the RRC inactive mode. Specifically, upon receiving the RRC release message including the suspension configuration information, the airborne UE 10-01 may transition to the RRC inactive mode, otherwise it may transition to the RRC idle mode.

[0190] At step 10-25, the over-the-air UE 10-01 in the RRC idle mode or the RRC inactive mode may obtain basic system information. The basic system information may indicate a master information block (MIB) and a system information block 1 (SIB1).

[0191] At step 10-30, the airborne UE 10-01 in RRC idle mode or RRC inactive mode may perform a cell selection procedure to camp on a cell suitable for the NR.

[0192] In step 10-35, the UE 10-01 in the RRC idle mode or the RRC inactive mode may obtain system information (e.g., SIB2, SIB3, SIB4, SIB5, new SIB) containing cell reselection information from the serving cell 10-02 to perform a cell reselection evaluation process. It is recommended that the serving cell according to an embodiment of the present disclosure broadcast multiple cell reselection priority (referred to as CRP) values ​​on each frequency. Specifically, - At least one of the first CRP (legacy CRP) or one or more second CRPs (CRPs for airborne UEs) of the serving frequency may be broadcast in SIB2.

[0193] - At least one of the first CRP (legacy CRP) or one or more second CRPs (CRPs for over-the-air UEs) for each inter-NR frequency may be broadcast in SIB4.

[0194] - At least one of the first CRP (legacy CRP) or one or more second CRPs (CRPs for airborne UEs) for each E-UTRAN frequency may be broadcast in SIB5.

[0195] - If the second CRP (CRP for air UEs) is not broadcast in the above system information, one or more second CRPs (CRP for air UEs) per frequency may be broadcast in the new SIB.

[0196] The CRP may indicate at least one of a cell reselection priority IE (information element) or a cell reselection sub-priority IE. As described in the above embodiments, the cell reselection priority IE may store an integer value (e.g., an integer value from 0 to 7), and the cell reselection sub-priority IE may store a decimal value (e.g., a decimal value among 0.2, 0.4, 0.6, 0.8). If only one of the two IEs is signaled, the UE 10-01 may derive the cell reselection priority value from the signaled value, and if both IEs are signaled, the UE may derive the cell reselection priority value by adding the two signaled values.

[0197] In addition, in the present disclosure, one or more altitude thresholds that are universally applicable regardless of frequency or one or more altitude thresholds for each frequency may be broadcast in the system information. For reference, in the present disclosure, a first CRP or one of the one or more second CRPs may be mapped for each altitude threshold.

[0198] The over-the-air UE 10-01 in RRC idle mode or RRC inactive mode may perform a cell reselection evaluation process. The cell reselection evaluation process may refer to the following series of processes: determining a reselection priority (reselection priority processing), performing frequency measurement according to the determined reselection priority by applying a measurement rule for cell reselection, and evaluating the cell reselection criteria accordingly to reselect a cell.

[0199] In step 10-40, an airborne UE 10-01 in RRC idle mode or RRC inactive mode may derive a reselection priority based on the system information received in step 10-25. UE 10-01 may determine the reselection priority only for the frequency of broadcasting the cell reselection priority value in the system information. If the UE flies at or above a specific altitude threshold broadcast in the system information (e.g., altitude 1 threshold <= altitude of the airborne UE < altitude 2 threshold), the UE 10-01 according to the present disclosure may determine the reselection priority by applying the second CRP associated with the specific altitude threshold (the second CRP associated with altitude 1 threshold) to at least one of the above-mentioned embodiments. If the UE 10-01 flies at or below the lowest altitude threshold broadcast in the system information, the reselection priority may be determined according to the fifth embodiment. For reference, since the interference caused by the airborne UE is different at different flight altitudes, it is effective for network management to determine the reselection priority according to the flight altitude.

[0200] In step 10-45, the airborne UE 10-01 in the RRC idle mode or the RRC inactive mode may perform frequency measurement for cell reselection. At this time, in order to minimize battery consumption, the UE may perform frequency measurement according to the cell reselection priority determined in step 10-40 by using the measurement rule of the above embodiment. For example, the measurement rule and measurement operation described in step 5-45 may be applied in step 10-45.

[0201] In step 10-50, the airborne UE 10-01 in RRC idle mode or RRC inactive state can determine a cell that meets the cell reselection criteria based on the measurement value for cell reselection obtained in step 10-45. This can follow the above-mentioned embodiment. For example, the cell reselection operation described in step 5-50 can be applied in step 6-50.

[0202] For reference, in the present disclosure, a list of cells that the aerial UE 10-01 can reselect (e.g., a PCI list for cell reselection of aerial UEs) can be broadcasted, and only cells belonging to the broadcasted cell list can be reselected. At this time, the UE 10-01 can perform reselection by applying the cell list only when it is flying at or above a specific altitude threshold. Alternatively, a list of cells that the aerial UE 10-01 cannot reselect can be broadcasted, and only cells that do not belong to the broadcasted cell list can be reselected. At this time, the UE 10-01 can perform reselection by applying the cell list only when it is flying at or above a specific altitude threshold. For reference, the parameters applied to Equation 2 (e.g., Q offset ) can be broadcasted separately in the system information, and the UE 10-01 can apply it to perform cell ranking (indicating equation 2). At this time, only when flying at or above a specific altitude threshold, the parameter can be broadcasted separately in the system information, and the UE 10-01 can perform cell ranking by applying the parameter sent separately with the signal to equation 2.

[0203] At step 10-55, before finally reselecting the candidate target cell, the over-the-air UE 10-01 in RRC idle mode or RRC inactive state receives system information (e.g., MIB or SIB1) broadcasted by the candidate target cell, and determines whether the reception level (Srxlev) and reception quality (Squal) of the candidate target cell meet the cell selection criterion (Srxlev>0 and Squal>0) referred to as the S criterion (Equation 1) based on the received system information. If Equation 1 is met and the candidate target cell is suitable, the UE 10-01 can reselect the candidate target cell.

[0204] Figure 5 , Figure 6 , Figure 7 , Figure 8 , Fig. 9 and Fig.10 The cell reselection and priority determination method according to the present disclosure is described. For ease of explanation, Figure 5 , Figure 6 , Figure 7 , Figure 8 , Fig. 9 and Fig.10 are separated, and since cell reselection and priority determination have the same purpose, Figure 5 , Figure 6 , Figure 7 , Figure 8 , Fig. 9 and Fig.10 Some of the configurations in can be combined and executed without contradicting each other. In addition, the same or similar processes as the above examples are omitted or summarized, and Figure 5 , Figure 6 , Figure 7 , Figure 8 , Fig. 9 and Fig.10 For the descriptions of the corresponding processes, corresponding information and corresponding messages, please refer to the descriptions in different examples.

[0205] Fig.11 is a diagram showing the structure of a UE according to an embodiment of the present disclosure.

[0206] Referring to the drawings, the UE may include a radio frequency (RF) processor 11-10, a baseband processor 11-20, a memory 11-30, and a controller 11-40. In addition, the controller 11-40 may include a multi-connection processor 11-42. In various embodiments of the present disclosure, the UE may be an airborne UE.

[0207] The RF processor 11-10 performs functions such as signal band conversion and amplification for sending and receiving signals through a wireless channel. That is, the RF processor 11-10 up-converts the baseband signal provided by the baseband processor 11-20 to an RF band signal and sends it through an antenna, and down-converts the RF band signal received through the antenna to a baseband signal. For example, the RF processor 11-10 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a digital-to-analog converter (DAC), and an analog-to-digital converter (ADC). Although only one antenna is shown in the figure, the UE may be provided with multiple antennas. In addition, the RF processor 11-10 may include multiple RF chains. In addition, the RF processor 11-10 may perform beamforming. For beamforming, the RF processor 11-10 may adjust the phase and amplitude of each signal sent and received through multiple antennas or antenna elements. In addition, the RF processor may perform MIMO (multiple input multiple output) and may receive multiple layers during MIMO operation.

[0208] The baseband processor 11-20 performs conversion between baseband signals and bit streams according to the physical layer specification of the system. For example, during data transmission, the baseband processor 11-20 generates complex symbols by encoding and modulating the transmission bit stream. In addition, during data reception, the baseband processor 11-20 recovers the received bit stream by demodulating and decoding the baseband signal provided from the RF processor 11-10. For example, in the case of using orthogonal frequency division multiplexing (OFDM), for data transmission, the baseband processor 11-20 generates complex symbols by encoding and modulating the transmission bit stream, maps the complex symbols to subcarriers, and composes OFDM symbols through inverse fast Fourier transform (IFFT) operations and cyclic prefix (CP) insertion. In addition, for data reception, the baseband processor 11-20 divides the baseband signal provided from the RF processor 11-10 in units of OFDM symbols, recovers the signal mapped to the subcarrier by fast Fourier transform (FFT), and recovers the received bit stream by demodulation and decoding.

[0209] As described above, the baseband processor 11-20 and the RF processor 11-10 send and receive signals. The baseband processor 11-20 and the RF processor 11-10 may be referred to as a transmitter, a receiver, a transceiver, or a communication unit. In addition, in order to support different wireless access technologies, at least one of the baseband processor 11-20 or the RF processor 11-10 may include multiple communication modules. In addition, in order to process signals of different frequency bands, at least one of the baseband processor 11-20 or the RF processor 11-10 may include different communication modules. For example, different wireless access technologies may include wireless LANs (e.g., IEEE 802.11), cellular networks (e.g., LTE), and the like. In addition, different frequency bands may include ultra-high frequency (SHF) bands (e.g., 2.NRHz, NRHz) and millimeter wave (mmWave) bands (e.g., 60GHz).

[0210] The memory 11-30 stores data such as basic programs, applications, and configuration information for the operation of the UE. Specifically, the memory 11-30 may store information about a second access node that performs wireless communication using a second radio access technology. The memory 11-30 provides stored data in response to a request from the controller 11-40.

[0211] The controller 11-40 controls the overall operation of the UE. For example, the controller 11-40 sends and receives signals through the baseband processor 11-20 and the RF processor 11-10. In addition, the controller 11-40 writes data to the memory 11-30 or reads data from the memory 11-30. To this end, the controller 11-40 may include at least one processor. For example, the controller 11-40 may include a communication processor (CP) for controlling communication and an application processor (AP) for controlling an upper layer such as an application. According to various embodiments of the present disclosure, the controller 11-40 may control the operation of the UE.

[0212] Fig.12 is a diagram showing a structure of a base station according to an embodiment of the present disclosure.

[0213] As shown, the base station includes an RF processor 12-10, a baseband processor 12-20, a backhaul communication unit 12-30, a memory 12-40, and a controller 12-50. In addition, the controller 12-50 may include a multi-connection processor 12-52.

[0214] The RF processor 12-10 performs functions such as signal band conversion and amplification for sending and receiving signals through a wireless channel. That is, the RF processor 12-10 up-converts the baseband signal provided by the baseband processor 12-20 to an RF band signal, and sends the converted signal through an antenna, and down-converts the RF band signal received by the antenna to a baseband signal. For example, the RF processor 12-10 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a DAC, and an ADC. Although only one antenna is shown in the figure, the first access node may be provided with multiple antennas. In addition, the RF processor 12-10 may include multiple RF chains. In addition, the RF processor 12-10 may perform beamforming. For beamforming, the RF processor 12-10 may adjust the phase and amplitude of each signal sent and received by multiple antennas or antenna elements. The RF processor may perform downlink MIMO operations by sending one or more layers.

[0215] The baseband processor 12-20 performs conversion between baseband signals and bit streams according to the physical layer specification of the first wireless access technology. For example, for data transmission, the baseband processor 12-20 generates complex symbols by encoding and modulating the transmission bit stream. In addition, for data reception, the baseband processor 12-20 recovers the received bit stream by demodulating and decoding the baseband signal provided from the RF processor 12-10. For example, in the case of using OFDM, for data transmission, the baseband processor 12-20 generates complex symbols by encoding and modulating the transmission bit stream, maps the complex symbols to subcarriers, and composes OFDM symbols through IFFT operations and CP insertion. In addition, for data reception, the baseband processor 12-20 divides the baseband signal provided from the RF processor 12-10 in units of OFDM symbols, recovers the signal mapped to the subcarrier by FFT operations, and recovers the received bit stream by demodulation and decoding. As described above, the baseband processor 12-20 and the RF processor 12-10 send and receive signals. Therefore, the baseband processor 12-20 and the RF processor 12-10 may be referred to as a transmitter, a receiver, a transceiver, a communication unit, or a wireless communication unit.

[0216] The backhaul communication unit 12-30 provides an interface for communicating with other nodes in the network. That is, the backhaul communication unit 12-10 converts a bit stream to be sent from a base station to another node (eg, a secondary base station or a core network) into a physical signal, and converts a physical signal received from another node into a bit stream.

[0217] The memory 12-40 stores data such as basic programs, applications, and configuration information for the operation of the base station. Specifically, the memory 12-40 can store information about the bearers assigned to the connected UEs and the measurement results reported from the connected UEs. In addition, the memory 12-40 can store information used as a criterion for determining whether to provide or suspend multiple connections to the UE. In addition, the memory 12-40 provides the stored data in response to a request from the controller 12-50.

[0218] The controller 12-50 controls the overall operation of the base station. For example, the controller 12-50 sends and receives signals through the baseband processor 12-20 and the RF processor 12-10 or through the backhaul communication unit 12-30. In addition, the controller 12-50 writes data to the memory 12-40 or reads data from the memory 12-40. To this end, the controller 12-50 may include at least one processor. According to various embodiments of the present disclosure, the controller 12-50 may control the operation of the base station.

[0219] The methods according to the embodiments described in the claims or specification of the present disclosure may be implemented in the form of hardware, software, or a combination thereof.

[0220] When implemented in software, a computer-readable storage medium storing one or more programs (software modules) may be provided. One or more programs stored in the computer-readable storage medium may be configured to be executed by one or more processors of the electronic device. One or more programs may include instructions for causing the electronic device to execute the method according to the embodiments described in the claims or specification of the present disclosure.

[0221] Such a program (software module, software) may be stored in a random access memory, a non-volatile memory (such as flash memory), a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), a magnetic disk storage device, a compact disk ROM (CD-ROM), a digital versatile disk (DVD), other types of optical storage devices, or a magnetic tape. Alternatively, such a program may be stored in a memory consisting of a combination of some or all of them. Furthermore, multiple component memories may be included.

[0222] In addition, such a program may be stored in a connectable storage device that can be accessed through a communication network such as the Internet, an intranet, a local area network (LAN), a wide area network (WLAN), or a storage area network (SAN), or through a communication network formed by a combination of the above networks. Such a storage device can access the device that executes the embodiments of the present disclosure through an external port. In addition, an independent storage device on a communication network can also access the device that executes the embodiments of the present disclosure.

[0223] In the embodiments of the present disclosure, according to the specific embodiments presented, the elements included in the present disclosure are represented in singular or plural form. However, for ease of description, singular or plural expression is appropriately selected according to the presented situation, and the present disclosure is not limited to a single element or plural elements. Those elements described in plural form can be configured as a single element, and these elements described in singular form can be configured as plural elements.

[0224] At the same time, the embodiments of the present disclosure disclosed in this specification and the accompanying drawings are provided only as specific examples to facilitate explanation of the technical details of the present disclosure and to help understand the present disclosure, and are not intended to limit the scope of the present disclosure. That is, it will be understood by those of ordinary skill in the art that other modifications can be made based on the technical ideas of the present disclosure. In addition, if the operation requires, some embodiments can be combined with each other. For example, one embodiment of the present disclosure and part of another embodiment can be combined with each other to operate a base station and a UE. In addition, the embodiments of the present disclosure are applicable to other communication systems, and other modifications can also be made based on the technical ideas of the embodiments.

Claims

1. A method performed by a terminal having an unmanned aerial vehicle (UAV) function in a wireless communication system, the method comprising: receiving system information from a base station, the system information including at least one of a first cell reselection priority level CRP or a second CRP for each frequency of a plurality of frequencies; determining cell reselection priorities of the multiple frequencies based on the system information; performing frequency measurement based on the cell reselection priorities of the plurality of frequencies; as well as reselecting a cell that meets a cell reselection criterion based on the frequency measurement, The first CRP is a CRP defined for a traditional UAV terminal, and the second CRP is a CRP defined for a terminal with a UAV function.

2. The method according to claim 1, in, In a case where both the first CRP and the second CRP are included for a first frequency, the terminal determines a cell reselection priority of the first frequency based on the second CRP.

3. The method according to claim 2, in, In a case where one of the first CRP or the second CRP is included for the first frequency, the terminal determines a cell reselection priority of the first frequency based on the included CRP.

4. The method according to claim 1, in, The terminal determines only the cell reselection priority of the frequency including the second CRP information among the multiple frequencies.

5. The method according to claim 4, in, In a case where the serving cell of the terminal does not include the second CRP, the cell reselection priority of the serving cell is set to a lowest priority, or the cell reselection priority of the serving cell is determined based on the first CRP of the serving cell.

6. The method according to claim 1, in, The system information also includes information about the altitude threshold; and Wherein, when the terminal flies at an altitude higher than or equal to the altitude threshold, the terminal determines the cell reselection priority by using the second CRP.

7. The method according to claim 1, in, defining one or more altitude thresholds for each frequency in the system information; and The multiple height thresholds are mapped to multiple second CRPs.

8. The method according to claim 1, in, Upon obtaining at least one of the first cell list information or the second cell list information of a terminal with UAV function, the terminal reselects at least one cell from the cells included in the first cell list information, or reselects a cell from the cells other than the cells included in the second cell list information.

9. A terminal having an unmanned aerial vehicle (UAV) function in a wireless communication system, the terminal comprising: Transceiver; as well as Controller, Wherein, the controller is configured to control: receiving system information from a base station, the system information including at least one of a first cell reselection priority level CRP or a second CRP for each frequency of a plurality of frequencies; determining cell reselection priorities of the multiple frequencies based on the system information; performing frequency measurements based on the cell reselection priorities of the plurality of frequencies; and reselecting a cell that meets a cell reselection criterion based on the frequency measurement, The first CRP is a CRP defined for a traditional UAV terminal, and the second CRP is a CRP defined for a terminal with a UAV function.

10. The terminal according to claim 9, in, In a case where both the first CRP and the second CRP are included for a first frequency, the terminal determines a cell reselection priority of the first frequency based on the second CRP.

11. The terminal according to claim 10, in, In a case where one of the first CRP or the second CRP is included for the first frequency, the terminal determines a cell reselection priority of the first frequency based on the included CRP.

12. The terminal according to claim 9, in, The terminal determines only the cell reselection priority of the frequency including the second CRP information among the multiple frequencies.

13. The terminal according to claim 12, in, In a case where the serving cell of the terminal does not include the second CRP, the cell reselection priority of the serving cell is set to the lowest priority, or the cell reselection priority of the serving cell is determined based on the first CRP of the serving cell.

14. The terminal according to claim 9, in, The system information also includes information about the altitude threshold; and Wherein, when the terminal flies at an altitude higher than or equal to the altitude threshold, the terminal determines the cell reselection priority by using the second CRP.

15. The terminal according to claim 9, in, Upon obtaining at least one of the first cell list information or the second cell list information of a terminal with UAV function, the terminal reselects at least one cell from the cells included in the first cell list information, or reselects a cell from the cells other than the cells included in the second cell list information.

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