Electronic device and method for performing emergency service in wireless communication system

Abstract

According to an embodiment, a method performed by a terminal in a wireless communication system is provided. The method includes receiving a radio resource control (RRC) message including a handover command to a new radio (NR) cell from a serving base station while performing an emergency service in a long term evolution (LTE) cell. The method includes identifying whether the NR cell supports a Reduction Capability (RedCap) function based on system information on the NR cell. The method includes switching an operation mode of the terminal from a RedCap mode to an NR normal mode if the NR cell does not support the RedCap function. The method includes performing the emergency service on the NR cell by accessing to the NR cell while the terminal is operating in the NR default mode. The method includes switching an operation mode of the terminal from the NR default mode to the RedCap mode in response to termination of the emergency service.

Description

Technical Field

[0001] The present disclosure relates to a wireless communication system. More specifically, the present disclosure relates to an electronic device and a method for performing an emergency service in a wireless communication system. Background Art

[0002] With the development of mobile communication networks, the 3rd Generation Partnership Project (3GPP) and the European Telecommunications Standards Institute (ETSI) are discussing solutions to reduce the complexity of performing channel access and communication for devices with low complexity. In a New Radio (NR) communication system, a terminal supporting a Reduced Capability (RedCap) function, also referred to as NR light, is defined.

[0003] The above information is presented only as related art to aid in understanding the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above is applicable as prior art with respect to the present disclosure. Summary of the Invention

[0004] Technical Solution Aspects of the present disclosure at least address the above problems and / or disadvantages and at least provide the advantages described below. Accordingly, an aspect of the present disclosure provides an electronic device and a method for performing an emergency service in a wireless communication system.

[0005] Additional aspects will be set forth in part in the following description, will be readily understood from the description, or may be obtained by practicing the presented embodiments.

[0006] According to an aspect of the present disclosure, a method performed by a terminal is provided. The method includes: receiving, from a serving base station, a Radio Resource Control (RRC) message including a handover command to a New Radio (NR) cell while performing an emergency service on a Long Term Evolution (LTE) cell. The method may include: identifying whether the NR cell supports a Reduced Capability (RedCap) function based on system information about the NR cell. The method may include: switching an operation mode of the terminal from a RedCap mode to an NR normal mode when the NR cell does not support the RedCap function. The method may include: performing the emergency service on the NR cell by accessing the NR cell when the terminal operates in the NR normal mode. The method may include: switching the operation mode of the terminal from the NR normal mode to the RedCap mode in response to termination of the emergency service.

[0007] According to one aspect of the present disclosure, a terminal in a wireless communication system is provided. The terminal includes: at least one transceiver; and at least one processor coupled to the at least one transceiver. The at least one processor is configured to: receive, from a serving base station, a radio resource control (RRC) message including a handover command to a new radio (NR) cell while performing an emergency service on a long-term evolution (LTE) cell. The at least one processor may be configured to: identify, based on system information about the NR cell, whether the NR cell supports a reduced-capability (RedCap) function. The at least one processor may be configured to: switch an operation mode of the terminal from a RedCap mode to an NR normal mode when the NR cell does not support the RedCap function. The at least one processor may be configured to: perform the emergency service on the NR cell by accessing the NR cell while the terminal operates in the NR normal mode. The at least one processor may be configured to: switch the operation mode of the terminal from the NR normal mode to the RedCap mode in response to termination of the emergency service.

[0008] According to one aspect of the present disclosure, a non-transitory computer-readable medium is provided. The non-transitory computer-readable medium includes a memory that stores instructions. When the instructions are executed by a processor, the instructions cause the terminal to: receive, from a serving base station, a radio resource control (RRC) message including a handover command to a new radio (NR) cell while performing an emergency service on a long-term evolution (LTE) cell; identify, based on system information about the NR cell, whether the NR cell supports a reduced-capability (RedCap) function; switch an operation mode of the terminal from a RedCap mode to an NR normal mode when the NR cell does not support the RedCap function; perform the emergency service on the NR cell by accessing the NR cell while the terminal operates in the NR normal mode; and switch the operation mode of the terminal from the NR normal mode to the RedCap mode in response to termination of the emergency service.

[0009] Other aspects, advantages, and salient features of the present disclosure will become readily apparent to those skilled in the art from the following detailed description, which discloses various embodiments of the present disclosure in conjunction with the accompanying drawings. Description of the Drawings

[0010] Figure 1 An example of a wireless communication system is shown.

[0011] Figure 2a An example of a control plane (C plane) is shown.

[0012] Figure 2bShows an example of the user plane (U plane).

[0013] Figure 3 Shows an example of the resource structure in the time domain and frequency domain.

[0014] Figure 4a And Figure 4b Shows the signal flow for performing emergency services when switching to an NR cell that does not support the Reduced Capability (RedCap) function.

[0015] Figure 5a Shows an example operation procedure of a terminal for operation mode switching.

[0016] Figure 5b Shows an example operation procedure of a terminal for performing communication in RedCap mode.

[0017] Figure 6a And Figure 6b Shows an example operation procedure of a terminal for managing a database for RedCap mode.

[0018] Figure 7a Shows an example of the screen of a terminal for an additional power saving mode using the RedCap function.

[0019] Figure 7b Shows an example operation procedure of a terminal for identifying a radio access technology (RAT) according to an additional power saving mode.

[0020] Figure 8 Shows an example operation procedure of a terminal for switching to RedCap mode.

[0021] Figure 9 Shows the signal flow for performing emergency services based on operation mode switching.

[0022] Figure 10 Shows an example operation procedure of a terminal for setting RedCap mode.

[0023] Figure 11 Shows an example operation procedure of a terminal for identifying a cell that supports the RedCap function.

[0024] Figure 12a Shows an example operation procedure of a terminal for performing emergency services in non-3GPP access or flight mode.

[0025] Figure 12b Shows an example operation procedure of a terminal for performing emergency services in the idle state.

[0026] Figure 13An example of a terminal performing an emergency service through an NR cell that does not support the RedCap function is shown.

[0027] Figure 14 An example of the functional configuration of a terminal is shown.

[0028] Figure 15 An example of the functional configuration of a base station is shown.

[0029] Throughout the drawings, it should be noted that the same reference numerals are used to depict the same or similar elements, features, and structures. Detailed Description

[0030] The following description with reference to the drawings is provided to assist in a comprehensive understanding of various embodiments of the present disclosure defined by the claims and their equivalents. It includes various specific details to aid understanding, but these are only considered exemplary. Thus, those of ordinary skill in the art will recognize that various changes and modifications can be made to the various embodiments described herein without departing from the scope of the present disclosure. Additionally, descriptions of well-known functions and configurations may be omitted for clarity and conciseness.

[0031] The terms and words used in the following description and claims are not limited to the meanings in the drawings, but are used by the inventors only to achieve a clear and consistent understanding of the present disclosure. Thus, it should be apparent to those skilled in the art that the following description of the various embodiments of the present disclosure is for illustrative purposes only and not for the purpose of limiting the present disclosure defined by the appended claims and their equivalents.

[0032] It should be understood that the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a component surface" includes reference to one or more such surfaces.

[0033] In the various examples of the present disclosure described below, hardware methods will be described as examples. However, since the various embodiments of the present disclosure can include technologies that utilize both hardware-based methods and software-based methods, the various embodiments are not intended to exclude software-based methods.

[0034] As used in the following description, terms for signaling (e.g., signal, information, message, signaling, etc.), terms for resources (e.g., symbol, time slot, subframe, radio frame, subcarrier, resource element (RE), resource block (RB), bandwidth part (BWP), occasion, etc.), terms for operation states (e.g., step, operation, procedure, etc.), terms for data (e.g., data packet, user flow, information, bit, symbol, codeword, etc.), terms for channels, terms for network entities, terms for components of a device, etc. are merely exemplified for ease of description. Thus, the present disclosure is not limited to the terms described below, and other terms with the same or equivalent technical meanings may be used therefor.

[0035] In addition, throughout the present disclosure, expressions such as "greater than" or "less than" may be used to determine whether a specific condition is met or satisfied, but it is merely a descriptive example and is not intended to exclude the meanings of "greater than or equal to" or "less than or equal to". A condition described as "greater than or equal to" may be replaced with "greater than", a condition described as "less than or equal to" may be replaced with "less than", and a condition described as "greater than or equal to and less than" may be replaced with "greater than and less than or equal to", respectively. In addition, hereinafter, "A" to "B" may refer to at least one element among the elements from A (including A) to B (including B). Hereinafter, "C" and / or "D" may refer to including at least one of "C" or "D", i.e., {"C", "D", or "C" and "D"}.

[0036] The present disclosure describes various embodiments using terms used in some telecommunication standards (e.g., the 3rd Generation Partnership Project (3GPP), the European Telecommunications Standards Institute (ETSI), the Scalable Radio Access Network (xRAN), and the Open Radio Access Network (O-RAN)), but they are for illustrative purposes only. The various embodiments of the present disclosure can be easily adapted and applied to other communication systems.

[0037] The Reduced Capability (RedCap) feature is a new feature introduced in 3GPP Release 17, which enables terminals supporting the RedCap feature to access the fifth-generation (5G) network in order to provide longer lifespan and lower cost. Compared with non-RedCap UEs, RedCap UEs have reduced complexity capabilities. For example, unlike traditional terminals, RedCap UEs must support 20 megahertz (MHz) in frequency range (FR) 1 (e.g., ~7.125 gigahertz (GHz)) and 100 MHz in frequency range (FR) 2 (e.g., 24.25 GHz to 71 GHz) within their maximum channel bandwidth. Hereinafter, for the purpose of explaining the present disclosure, a terminal capable of supporting such a reduced capability (RedCap) feature may be referred to as a RedCap device or a RedCap UE. There are two types of RedCap UEs.

[0038] The first type of devices can only support the RedCap feature and includes wearable devices (e.g., smart watches, medical devices, augmented reality (AR), virtual reality (VR) glasses, etc.), industrial wireless sensors, video surveillance, etc.

[0039] The second type of devices can operate in either the basic mode (or traditional mode) or the RedCap mode. In the RedCap mode, due to some network-related features (e.g., discontinuous reception (DRX) extension, bandwidth part (BWP) reduction, radio resource management (RRM) relaxation, etc.), the device can have an excellent effect of reducing power consumption compared with the basic mode. The basic mode refers to the communication mode for RedCap UEs in the NR communication system, i.e., the normal communication mode other than the RedCap mode.

[0040] Hereinafter, the present disclosure relates to a device and method for performing an emergency service in an NR cell without performing radio resource control (RRC) connection reestablishment (RRE) on an existing LTE cell when a RedCap UE receives a handover command to an NR cell that does not support the RedCap feature while performing an emergency service in an LTE cell. More specifically, the present disclosure describes a technique for switching the operation mode of the UE from the RedCap mode to the NR normal mode to perform an emergency service in the NR cell and search for an NR cell supporting the RedCap feature again.

[0041] Figure 1 An example of a wireless communication environment is shown.

[0042] Refer to Figure 1 , Figure 1FIG. 110 shows a terminal 110, a first base station 120, and a second base station 130, which are part of nodes using a wireless channel in a wireless communication system. The terminal 110 may be connected to the first base station 120 or the second base station 130, or may be connected to both the first base station 120 and the second base station 130.

[0043] The terminal 110 is a device through which a user communicates with the base station 120 via a wireless channel. The link from the base station 120 to the terminal 110 is referred to as the downlink (DL), and the link from the terminal 110 to the base station 120 is referred to as the uplink (UL). In addition, although Figure 1 not shown in FIG. 110, the terminal 110 and another terminal may communicate with each other via a wireless channel. In this case, the device-to-device link (D2D) between the terminal 110 and the other terminal may be referred to as a sidelink, and the sidelink may be used interchangeably with the PC5 interface. In some other embodiments, the terminal 110 may operate without any user participation. According to an embodiment, the terminal 110 is a device or apparatus that performs machine type communication (MTC) and may not be carried by a user. In addition, according to an embodiment, the terminal 110 may be a narrowband (NB) Internet of Things (IoT) device. According to an embodiment, the terminal 110 may operate as a RedCap UE. In addition to the term "terminal", the terminal 110 may be referred to as a "user equipment (UE)", a "customer premise equipment (CPE)", a "mobile station", a "subscriber station", a "remote terminal", a "wireless terminal", an "electronic device", or any other term having an equivalent technical meaning.

[0044] Base station 120 or base station 130 is a network infrastructure that provides wireless access to terminal 110. Base station 120 or base station 130 has a coverage area defined based on the distance capable of transmitting signals. According to an embodiment, base station 120 may provide an access network according to a fourth-generation (4G) communication scheme (e.g., Long-Term Evolution (LTE)). Base station 120 may provide one or more LTE cells. In addition to the term "base station", base station 120 may be referred to as an "access point (AP)", "eNodeB (eNB)", "radio point", "transmission / reception point (TRP)", or any other term having an equivalent technical meaning. Further, according to an embodiment, base station 130 may provide an access network according to a 5G communication scheme (e.g., New Radio (NR)). Base station 130 may provide one or more NR cells. In addition to the term "base station", base station 130 may be referred to as an "access point", "next generation Node B (gNB)", "5G Node B (5gNB)", "radio point", "transmission / reception point (TRP)", or any other term having an equivalent technical meaning.

[0045] Base station 120 or base station 130 may perform beamforming with terminal 110. For example, base station 130 and terminal 110 may transmit and receive radio signals in a relatively low frequency band (e.g., FR1 of NR). In addition, base station 130 and terminal 110 may transmit and receive radio signals in a relatively high frequency band (e.g., FR2 (or FR2-1, FR2-2, FR2-3) or FR3 of NR) or a millimeter wave (mmWave) frequency band (e.g., 28 GHz, 30 GHz, 38 GHz, or 60 GHz). To improve the channel gain, base station 130 and terminal 110 may perform beamforming. Here, beamforming may include transmit beamforming and receive beamforming. Base station 130 and terminal 110 may assign directivity to the transmitted or received signal. To this end, base station 130 and terminal 110 may select a serving beam through a beam search or beam management process. After selecting the serving beam, subsequent communication may be performed through a resource having a quasi-co-location (QCL) relationship with the resource transmitting the serving beam.

[0046] If the large-scale characteristics of the channel transmitting symbols on the first antenna port can be inferred from the channel transmitting symbols on the second antenna port, it may be determined that the first antenna port and the second antenna port have a QCL relationship. For example, the large-scale characteristics may include at least one of delay spread, Doppler spread, Doppler frequency shift, average gain, average delay, and spatial receiver parameters.

[0047] Figure 2aAn example of the control plane (C plane) is shown. Refer to Figure 2a for the description of each layer in the NR communication protocol, but at least some of the descriptions can also be equivalently applied to the LTE communication protocol between the terminal 110 and the base station 120.

[0048] Refer to Figure 2a In the C plane, the terminal 110 and the core network entity (e.g., the access and mobility management entity (AMF) 235) can perform non-access stratum (NAS) signaling. In the C plane, the terminal 110 and the base station 130 can perform communication according to the specified protocol in each of the radio resource control (RRC) layer, the packet data convergence protocol (PDCP) layer, the radio link control (RLC) layer, the media access control (MAC) layer, and the physical (PHY) layer.

[0049] The main functions of the RRC layer may include at least some of the following functions: - Broadcast of access stratum (AS) and NAS related system information; - Paging initiated by the 5GC (5G core) or the NG-RAN (next generation radio access network); - Establishment, maintenance, and release of the RRC connection between the UE and the NG-RAN, including: - Addition, modification, and release of carrier aggregation, and - Addition, modification, and release of the dual connection between NR or E-UTRA and NR; - Security functions including key management; - Setup, configuration, maintenance, and release of the signaling radio bearer (SRB) and the data radio bearer (DRB); - Mobility functions include: - Handover and context transfer, - UE cell selection and reselection, and cell selection and reselection control, and - Mobility between RATs; - Quality of service (QoS) management functions; - Control of UE measurement reports and reporting; - Detection and recovery of radio link failures; and - Sending information from the UE to the NAS / from the NSA to the UE.

[0050] The main functions of the PDCP layer may include at least some of the following functions: - Header compression and decompression (only robust header compression (ROHC)); - Transmission of user data; - Sequential delivery of upper layer protocol data units (PDUs); - Out-of-order delivery of upper layer PDUs; - Reordering of PDCP PDUs for reception; - Duplicate detection of lower layer service data units (SDUs); - Retransmission of PDCP SDUs; - Encryption and decryption; and - Timer-based SDU discard in the uplink.

[0051] The main functions of the RLC layer may include at least some of the following functions: - Transmission of upper layer PDUs; - In-order delivery of upper layer PDUs; - Out-of-order delivery of upper layer PDUs; - Automatic repeat request (ARQ) function (error correction via ARQ); - Concatenation, segmentation, and reassembly of RLC SDUs; - Re-segmentation of RLC data PDUs; - Reordering of RLC data PDUs; - Duplicate detection; - Protocol error detection; - RLC SDU discard; and - RLC re-establishment.

[0052] The MAC layer may be connected to multiple RLC layer devices configured in a terminal, and the main functions of the MAC may include at least some of the following functions: - Mapping between logical channels and transport channels; - Multiplexing / demultiplexing of MAC SDUs; - Scheduling information reporting; - Hybrid automatic repeat request (HARQ) function (error correction via HARQ); - Priority handling between logical channels of a UE; - Priority handling between UEs via dynamic scheduling; - Multimedia broadcast / multicast service (MBMS) service identification; - Transmission format selection; and - Padding.

[0053] The physical layer may include channel coding and modulation of upper layer data to turn the upper layer data into orthogonal frequency division multiplexing (OFDM) symbols for transmitting the OFDM symbols to the wireless channel, or demodulating and channel decoding the OFDM symbols received through the wireless channel to send the OFDM symbols to the upper layer.

[0054] Figure 2b shows an example of the user plane (U-plane). In Figure 2a , the description of each layer is described in the NR communication protocol, and at least some of the descriptions can also be equivalently applied to the LTE communication protocol between the terminal 110 and the base station 120.

[0055] Referring to Figure 2b , in the U-plane, the terminal 110 and the base station 130 can perform communication according to the specified protocol in each of the service data adaptation protocol (SDAP) layer, PDCP layer, RLC layer, MAC layer, and PHY layer. For the PDCP layer, RLC layer, MAC layer, and PHY layer, except for the SDAP layer, reference can be made to the description of Figure 3 .

[0056] The SDAP layer can provide QoS flows of the 5GC. A single protocol entity of the SDAP can be configured for each individual PDU session, and the functions of the SDAP layer can include at least some of the following functions: Mapping between QoS flows and data radio bearers; and Showing the QoS flow ID (QFI) in both DL and UL packets.

[0057] Figure 3 shows an example of the resource structure in the time domain and frequency domain. In addition, Figure 3 shows the basic structure of the time-frequency domain, which is a radio resource region where data or control channels are transmitted in the downlink or uplink.

[0058] Referring to Figure 3 , the horizontal axis represents the time domain, and the vertical axis represents the frequency domain. The smallest transmission unit in the time domain is the OFDM symbol, and N symb OFDM symbols 302 are collected to form a time slot 306. The length of a subframe is defined as 1.0 ms, and the length of a radio frame 314 is defined as 10 ms. The smallest transmission unit in the frequency domain is the subcarrier, and the carrier bandwidth that constitutes the resource grid is composed of N BW subcarriers 304.

[0059] In the time-frequency domain, the basic unit of a resource is a resource element (hereinafter referred to as "RE") 312, which can be represented by an OFDM symbol index and a subcarrier index. A resource block can include multiple resource elements. In the LTE system, a resource block (RB) (or a physical resource block, hereinafter referred to as "PRB") is defined as N symb consecutive OFDM symbols in the time domain and N SC RB consecutive subcarriers in the frequency domain. In the NR system, the resource block RB 308 can be defined as N in the frequency domainSC RB consecutive subcarriers 310. One RB 308 includes N SC RB REs 312. Generally, the minimum transmission unit of data is an RB, and the number of subcarriers is N SC RB = 12. The frequency domain may include common resource blocks (CRBs). Physical resource blocks (PRBs) can be defined in a bandwidth part (BWP) in the frequency domain. The number of CRBs and PRBs can be determined according to the subcarrier spacing. The data rate can increase proportionally to the number of RBs scheduled for the terminal.

[0060] In the NR system, in the case where a frequency division duplex (FDD) system operates by dividing the downlink and uplink by frequency, the downlink transmission bandwidth and the uplink transmission bandwidth can be different from each other. The channel bandwidth represents the radio frequency (RF) bandwidth corresponding to the system transmission bandwidth. Table 1 below shows some correspondences between the system transmission bandwidth, subcarrier spacing (SCS), and channel bandwidth defined in the NR system in a band below x GHz (e.g., FR1 (310 MHz to 7125 MHz)). In addition, Table 2 below shows some correspondences between the transmission bandwidth, subcarrier spacing, and channel bandwidth defined in the NR system in a band above y GHz (e.g., FR2 (24250 MHz to 52600 MHz) or FR2-2 (52600 MHz to 71000 MHz)). For example, an NR system with a 100 MHz channel bandwidth at a 30 kHz subcarrier spacing has a transmission bandwidth composed of 273 RBs. In Tables 1 and 2, N / A may be a bandwidth subcarrier combination not supported by the NR system.

[0061] Table 1

[0062] Table 2

[0063] Hereinafter, throughout this disclosure, a RedCap UE means a UE with reduced capabilities. According to an embodiment, the terminal 110 can be a RedCap UE. A cell supporting the RedCap function refers to a cell that supports RedCap UEs and satisfies the following conditions.

[0064] For FR1, the maximum bandwidth is 20 MHz, and for FR2, the maximum bandwidth is 100 MHz. UE functions and their corresponding capabilities related to a UE bandwidth greater than 20 MHz in FR1 or greater than 100 MHz in FR2 are not supported by RedCap UEs.

[0065] The maximum required number of supported DRBs is 8.

[0066] The required supported length of the PDCP sequence number (SN) is 12 bits, and 18 bits are optional.

[0067] The required supported length of the RLC acknowledged mode (AM) SN is 12 bits, and 18 bits are optional.

[0068] For FR1, when supporting one Rx branch, one downlink (DL) multiple-input multiple-output (MIMO) layer can be supported; when supporting two Rx branches, two DL MIMO layers can be supported. For FR2, one or two DL MIMO layers can be supported, and two Rx branches can always be supported. For FR1 and FR2, RedCap UEs do not support UE functions and their corresponding capabilities related to two or more UE Rx branches or two or more DL MIMO layers, as well as UE functions and their corresponding capabilities related to one or more UE Tx branches or one or more UL MIMO layers.

[0069] UE functions and their corresponding capabilities related to carrier aggregation (CA), multi-radio access technology dual connectivity (MR-DC), dual adaptive protocol stack (DAPS), conditional primary and secondary cell (PSCell) change (CPAC), and integrated access and backhaul (IAB) (i.e., RedCap UEs are not expected to operate as IAB nodes) are not supported by RedCap UEs.

[0070] According to an embodiment, the terminal 110 can identify whether a 5G NR cell supports the RedCap function based on system information. The system information may refer to the information included in the system information block (SIB) 1 of the corresponding cell. For example, SIB 1 may include the following information: RedCap configuration information ("RedCap-ConfigCommonSIB"): It may include information indicating whether the cell is allowed to support half-duplex frequency division duplex (FDD) (e.g., "halfDuplexRedCap-Allowed" IE), information indicating that the cell is barred for RedCap UEs with one receive branch (i.e., 1Rx branch) (e.g., "cellBarredRedCap1Rx" IE), and information indicating that the cell is barred for RedCap UEs with two receive branches (i.e., 2Rx branch) (e.g., "cellBarredRedCap2Rx" IE).

[0071] Intra - frequency selection information ("intraFreqReselectionRedCap"): It may include information for controlling cell selection / reselection of cells within a frequency for a RedCap UE when a cell is prohibited or treated as prohibited for a RedCap UE. In the absence of the information, the terminal 110 may consider the cell as prohibited. That is, the terminal 110 may consider that the corresponding cell does not support RedCap.

[0072] The terminal 110 may identify whether the 5G NR cell providing the system information supports the RedCap function based on at least a part of the information included in the system information. For example, when the "intraFreqReselectionRedCap" IE is included in SIB1, the terminal 110 may identify that the corresponding cell supports the RedCap function. Another example is that when the information indicating that the cell is prohibited for a RedCap UE with 2Rx branches is included in SIB1, the terminal 110 may identify that the corresponding cell does not support the RedCap function.

[0073] Figure 4a and Figure 4b shows the signal flow for performing an emergency service when performing a handover to an NR cell that does not support the reduced - capability (RedCap) function. Some types of 5G NR cells may support terminals in the NR normal mode, terminals in the RedCap mode, or both terminals in the NR normal mode and terminals in the RedCap mode. The type of cell operation mode switch may depend on network installation or cell load - balancing information at a specific time or in a specific area. Emergency services are one of the services that are essential for users. When a user requests an emergency service, the highest - priority task should be set for the emergency service, and the highest - priority task should be performed without any damage or loss. The terminal 110 operating in the 5G RAT may support the legacy mode and the RedCap mode and may be configured to operate in the RedCap mode. In a specific area or at a specific time, the network may cause the terminal 110 to fallback from an NR cell (or may be referred to as a 5G cell or a 5G NR cell) to an LTE cell. When operating in the RedCap mode in a 5G NR cell, the terminal 110 may receive a mobility command (i.e., a handover command) towards the LTE cell.

[0074] Reference Figure 4a In operation 401, the terminal 110 may perform a registration process with the LTE cell 471 of the base station 120 and initiate an emergency service. The base station 120 may include an eNB. The terminal 110 may perform a random - access process with the LTE cell 471 of the base station 120. Although not shown in Figure 4aAs shown, the base station 120 can perform a registration process for the terminal 110 in the LTE cell 471 with a core network entity (e.g., a Mobility Management Entity (MME)) via signaling. When the LTE cell 471 is registered, the terminal 110 can establish an emergency service through the LTE cell 471.

[0075] In operation 403, the terminal 110 can perform an emergency service on the LTE cell 471 and the base station 120.

[0076] In operation 405, the terminal 110 can receive a handover command for the NR cell 473 from the LTE cell 471 of the base station 120. The terminal 110 can receive the handover command for the NR cell 473 while performing an emergency service in the LTE cell 471. The terminal 110 can receive an inter-RAT handover command indicating a target 5G cell from the serving LTE cell 471. The handover command can be sent on the LTE cell 471. The handover command can be sent via RRC signaling. For example, the terminal 110 can receive an RRC connection reconfiguration message on the 3GPP LTE standard. The RRC connection reconfiguration message can include information indicating the handover command and information indicating the target NR cell (e.g., the NR cell 473).

[0077] In operation 407, the terminal 110 may identify that the NR cell 473 does not support RedCap. The terminal 110 may obtain system information about the target cell through a handover command. The target cell may be the NR cell 473. The terminal 110 may identify whether the NR cell 473 supports RedCap based on the system information about the NR cell 473. According to an embodiment, the system information may be SIB1 of the NR standard. According to an embodiment, the terminal 110 may identify whether the NR cell 473 supports RedCap based on at least one of the intra-frequency selection information (e.g., "intraFreqReselectionRedCap") or RedCap configuration information (e.g., information indicating whether the cell supports half-duplex frequency division duplex (FDD) (e.g., "halfDuplexRedCap-Allowed" IE), information indicating that the cell is prohibited for a RedCap UE with one receive branch (i.e., 1Rx branch) (e.g., "cellBarredRedCap1Rx" IE), information indicating that the cell is prohibited for a RedCap UE with two receive branches (i.e., 2Rx branch) (e.g., "cellBarredRedCap2Rx" IE)) included in SIB1. For example, the terminal 110 may identify that the NR cell 473 is prohibited based on at least one of the IEs in the RedCap configuration information (e.g., "cellBarredRedCap1Rx" IE, "cellBarredRedCap2Rx" IE, or "halfDuplexRedCap-Allowed" IE). The terminal 110 may identify that the prohibited NR cell 473 does not support the RedCap function. In addition, for example, when the intra-frequency selection information (e.g., "intraFreqReselectionRedCap") does not exist in SIB1, the terminal 110 may identify that the NR cell 473 is prohibited. The terminal 110 may identify that the prohibited NR cell 473 does not support the RedCap function.

[0078] In operation 409, the terminal 110 may determine to maintain the connection with the serving LTE cell.

[0079] In operation 411, the terminal 110 may perform an RRC connection reestablishment (RRE) procedure with the LTE cell 471. According to the current technical standard, when the target 5G cell does not support RedCap, the terminal 110 may perform an RRC procedure to maintain the connection in the serving LTE cell. The terminal 110 may send an RRE connection reestablishment request message to the base station 120 on the LTE cell 471. The terminal 110 may receive an RRC connection reestablishment message for the LTE cell 471 from the base station 120. The terminal 110 may send an RRC connection reestablishment completion message for the LTE cell 471 to the base station 120. The terminal 110 may perform communication on the LTE cell 471 through an effective RRC connection according to a series of messages. However, the RRE procedure may include a specific service disconnection time. In addition, when the signal quality of the LTE cell 471 deteriorates, a higher transmit power is required, and thus, the power consumption of the terminal 110 may increase. Subsequently, the signal of the LTE cell 471 may become much worse, such that the emergency service may be interrupted and the RRC connection may be disconnected. Frequent recovery procedures may result in signaling overhead for both the UE and the network.

[0080] To solve the above problems, the RedCap support procedure according to an embodiment of the present disclosure proposes a solution for switching the operation mode of the terminal 110 to maintain the emergency service under normal circumstances and then reduce the power consumption and signaling overhead of the terminal 110.

[0081] Reference Figure 4b, in operation 450, the terminal 110 may perform an emergency service based on an operation mode switch. Instead of performing an RRE process on the LTE cell 471 of the base station 120, the terminal 110 may perform an access to the NR cell 473 of the base station 130 according to the handover command of operation 405. Through the operation mode switch, the terminal 110 may perform an access to the NR cell 473. The terminal 110 may change the operation mode of the terminal 110 from the RedCap mode to the NR normal mode. The terminal 110 may perform a connection to the NR cell 473 through a random access procedure. Thereafter, the terminal 110 may perform a registration procedure to a core network entity (e.g., AMF 235) through the NR cell 473 by way of non-access stratum (NAS) signaling. The AMF 235 may identify and authenticate the terminal 110, and then send a response message accepting or rejecting the registration to the terminal 110 through the NR cell 473. When the registration of the NR cell 473 is completed, the terminal 110 may perform an emergency service on the NR cell 473. Here, the emergency service may be performed in the NR normal mode other than the RedCap mode of the terminal 110. Once the emergency service is terminated, the terminal 110 may change the operation mode from the NR normal mode to the RedCap mode. The terminal 110 may identify the NR cell 473 supporting RedCap and may perform an access procedure to the NR cell 473.

[0082] Through the operation mode switch for RedCap according to an embodiment, an emergency service may be continuously performed in the LTE cell 471 as a serving cell without interruption / loss of the service due to a poor signal state. In particular, in a case where the LTE cell 471 needs to use a relatively high Tx power for packet data transmission, the power consumption of the terminal 110 may be increased. In addition, an unnecessary RRE process does not occur, and thus the signaling overhead may be reduced.

[0083] Figure 5a An example of an operation flow of a terminal (e.g., the terminal 110) for an operation mode switch is shown. Throughout the present disclosure, the term "operation mode" may refer to a state indicating whether a terminal supporting the RedCap function is operating in the RedCap mode or in the NR normal mode other than the RedCap mode (i.e., an NR traditional communication scheme other than the RedCap mode).

[0084] Reference Figure 5a, in operation 501, the terminal 110 may receive a handover command for an NR cell. According to an embodiment, the terminal 110 may receive the handover command while performing an emergency service in the RedCap mode. According to an embodiment, the terminal 110 may receive an RRC reconfiguration message from a serving base station (e.g., base station 120). The RRC reconfiguration message may include information indicating the NR cell. For example, the serving base station may be an eNB providing an LTE cell.

[0085] In operation 503, the terminal 110 may identify whether the NR cell supports RedCap. The terminal 110 may obtain system information about the target cell through the handover command. The target cell may be an NR cell. The terminal 110 may identify whether the NR cell supports RedCap based on the system information about the NR cell. According to an embodiment, the system information may be SIB1 of the NR standard. According to an embodiment, the terminal 110 may identify whether the NR cell supports RedCap based on at least one of the intra-frequency selection information (e.g., "intraFreqReselectionRedCap") or RedCap configuration information (e.g., information indicating whether the cell supports half-duplex frequency division duplex (FDD) (e.g., "halfDuplexRedCap-Allowed" IE), information indicating that the cell is prohibited for a RedCap UE with one receive branch (i.e., 1Rx branch) (e.g., "cellBarredRedCap1Rx" IE), information indicating that the cell is prohibited for a RedCap UE with two receive branches (i.e., 2Rx branch) (e.g., "cellBarredRedCap2Rx" IE)) included in SIB1. For example, the terminal 110 may identify that the NR cell is prohibited based on at least one of the IEs in the RedCap configuration information (e.g., "cellBarredRedCap1Rx" IE, "cellBarredRedCap2Rx" IE, or "halfDuplexRedCap-Allowed" IE). The terminal 110 may identify that the prohibited NR cell does not support the RedCap function. In addition, for example, when the intra-frequency selection information (e.g., "intraFreqReselectionRedCap") does not exist in SIB1, the terminal 110 may identify that the NR cell is prohibited. The terminal 110 may identify that the prohibited NR cell does not support the RedCap function.

[0086] In the case where the NR cell does not support RedCap, the terminal 110 may perform operation 505. In the case where the NR cell supports RedCap, the terminal 110 may perform operation 513.

[0087] In operation 505, the terminal 110 may switch the operation mode to the NR normal mode. The terminal 110 may access the NR cell to continue the emergency service. However, since the NR cell does not support RedCap, the terminal 110 may switch the operation mode from the RedCap mode to the NR normal mode. The terminal 110 may switch the operation mode to the NR normal mode to access the NR cell.

[0088] In operation 507, the terminal 110 may perform a registration process on the NR cell. The terminal 110 may perform a random access process with the NR cell. The terminal 110 may send a random access preamble (RAP) to the base station of the NR cell (e.g., base station 130). The terminal 110 may use the allocated random access channel (RACH) to perform the random access process. The terminal 110 may receive a random access response (RAR) from the base station 130. The terminal 110 may transmit an uplink message (e.g., physical uplink shared channel (PUSCH)) including the identity information of the terminal 110 to the base station 130. The terminal 110 may receive a downlink message indicating the resolution of the contention from the base station 130. The terminal 110 may send an RRC connection completion message to the base station 130. Thereafter, when the registration process in the core network is completed, the terminal 110 may perform the emergency service on the NR cell. When operating in the NR normal mode, the terminal 110 may perform the emergency service on the NR cell.

[0089] In operation 509, the terminal 110 may identify whether the emergency service is terminated. When the emergency service is terminated, the terminal 110 may perform operation 511. The terminal 110 may maintain the connection with the NR cell until the emergency service is terminated. The terminal 110 may maintain the connection with the NR cell in the NR normal mode until the emergency service is terminated.

[0090] In operation 511, the terminal 110 may switch the operation mode to the RedCap mode. Since the emergency service is terminated, the terminal 110 may determine that the connection with the NR cell that does not support the RedCap function is no longer maintained. The terminal 110 may switch the operation mode of the terminal 110 from the NR normal mode to the RedCap mode to save power in the terminal 110.

[0091] In operation 513, the terminal 110 may perform communication in the RedCap mode. The terminal 110 may identify a cell that supports RedCap. According to an embodiment, the terminal 110 may identify a cell that supports RedCap based on a database in which the carrier frequencies of the cells that support RedCap are stored. In addition, according to an embodiment, the terminal 110 may identify a cell that supports RedCap based on a frequency scan using a frequency list stored in the terminal 110.

[0092] Figure 5b An example operation procedure of a terminal (e.g., terminal 110) for performing communication in the RedCap mode is shown.

[0093] Reference Figure 5b , in operation 551, the terminal 110 may identify that the current cell does not support the RedCap function. The terminal 110 may identify whether the currently discovered cell supports the RedCap function based on the system information. According to an embodiment, the terminal 110 may identify whether the discovered cell supports the RedCap function based on whether a specific IE is included in the system information of the discovered cell. For example, when there is no intra-frequency selection information (e.g., "intraFreqReselectionRedCap") in the SIB1 message of the discovered cell, the terminal 110 may identify that the discovered cell does not support the RedCap function.

[0094] In addition, according to an embodiment, the terminal 110 may identify whether the discovered cell supports the RedCap function based on the capabilities of the terminal 110 and a specific IE in the system information of the discovered cell. For example, the terminal 110 may identify whether the discovered cell is prohibited by the terminal 110 based on the information indicating the limit of the number of Rx branches in the SIB1 message of the discovered cell and the capabilities of the terminal 110. The terminal 110 may identify that the discovered cell does not support the RedCap function based on identifying that the discovered cell is prohibited by the terminal 110.

[0095] In operation 553, the terminal 110 may determine whether a RedCap cell is identified. A RedCap cell refers to a cell that supports the RedCap function. The terminal 110 may determine whether a RedCap cell is identified in the database for RedCap. When a RedCap cell is identified, the terminal 110 may perform operation 555. When no RedCap cell is identified, the terminal 110 may perform operation 557.

[0096] In operation 555, the terminal 110 may perform a registration process to the identified RedCap cell. The terminal 110 may establish an RRC connection with the RedCap cell by performing a random access process on the RedCap cell. Thereafter, when the registration process is completed, the terminal 110 may perform communication services (e.g., emergency services) through the RRC connection.

[0097] In operation 557, the terminal 110 may perform cell search based on a frequency list. The frequency list is a frequency list for frequency scanning and may include one or more frequencies (e.g., NR Absolute Radio Frequency Channel Number (NR ARFCN)). The terminal 110 may perform cell search through frequency scanning. When the terminal 110 identifies an NR cell that supports the RedCap function through frequency scanning, the terminal 110 may perform an access procedure (e.g., a random access procedure) with the identified NR cell. The terminal 110 may establish an RRC connection with the NR cell. Thereafter, when the registration process is completed, the terminal 110 may perform communication services (e.g., emergency services) through the RRC connection.

[0098] Figure 6a and Figure 6b illustrates an example operation flow of a terminal (e.g., terminal 110) for managing a database for the RedCap mode. The database may store information about RedCap cells. Figure 6a illustrates an example of adding a cell that supports the RedCap function to the database, and Figure 6b illustrates an example of removing a cell stored in the database.

[0099] Refer to Figure 6a , in operation 601, the terminal 110 may obtain information about an NR cell. For example, when the terminal 110 is searching for a Public Land Mobile Network (PLMN), in the idle mode, or in cell selection, in cell reselection, or in handover, the terminal 110 may obtain information about the NR cell. According to an embodiment, the terminal 110 may obtain information about the NR cell through a broadcast message. For example, the terminal 110 may obtain system information about an NR cell in the idle state. In addition, according to an embodiment, the terminal 110 may obtain system information about the NR cell through an RRC message. For example, the terminal 110 may obtain system information about an NR cell in the connected state. The RRC message indicating a handover command to the NR cell may include system information about the NR cell.

[0100] In operation 603, the terminal 110 may identify whether the NR cell supports RedCap. According to an embodiment, the terminal 110 may identify whether the NR cell supports RedCap based on the scheme illustrated in operation 503 (e.g., determined based on whether frequency-in selection information ("intraFreqReselectionRedCap" IE) is included in SIB1). When the NR cell does not support RedCap, the terminal 110 may terminate the storage process for the database for RedCap. However, when the NR cell supports RedCap, the terminal 110 may perform operation 605.

[0101] In operation 605, the terminal 110 may store information about the NR cell in a database. In response to determining that the NR cell supports RedCap, the terminal 110 may store information about the NR cell in a database. According to an embodiment, the terminal 110 may store the tracking area code (TAC) for the NR cell. In addition, according to an embodiment, the terminal 110 may store the frequency information of the NR cell (e.g., NR ARFCN). In addition, according to an embodiment, the terminal 110 may store the PLMN identifier (ID) for the NR cell. In addition, according to an embodiment, the terminal 110 may store the tracking area identifier (TAI) for the NR cell. Further, according to an embodiment, the terminal 110 may store at least one of the TAC, frequency information, PLMN ID, or TAI for the NR cell. For example, the database may have the following format.

[0102] Table 3

[0103] In operation 607, the terminal 110 may perform communication in RedCap mode. The terminal 110 may communicate on the NR cell according to the RedCap mode. This is because the NR cell supports RedCap. The terminal 110 may fallback to the LTE cell while the terminal 110 performs communication in RedCap mode. According to an embodiment, the terminal 110 may perform Figure 5a operations while performing communication in RedCap mode on the LTE cell.

[0104] Refer to Figure 6b , in operation 651, the terminal 110 may identify whether all cells in the database do not support RedCap. The database may refer to a storage device configured to store cells that support the RedCap function. When at least one cell in the database supports RedCap, the terminal 110 may perform operation 653. When no cell in the database supports RedCap, the terminal 110 may perform operation 657.

[0105] In operation 653, the terminal 110 may identify whether the NR cell supports RedCap. The terminal 110 may identify the NR cell in the database. When the NR cell supports RedCap, the terminal 110 may perform operation 655. When the NR cell does not support RedCap, the terminal 110 may perform operation 657.

[0106] In operation 655, the terminal 110 may perform communication in RedCap mode. The terminal 110 may communicate with the RedCap mode on the NR cell.

[0107] In operation 657, the terminal 110 may remove cell information from the database. Since the NR cells identified in the database no longer support the RedCap mode, the terminal 110 may remove the cell information corresponding to the NR cells. For example, in response to determining that all cells scanned by the ARFCN selected from the database do not support RedCap, the terminal 110 may remove the set of ARFCN and TAC from the database.

[0108] In Figure 6b , an evaluation is performed on only one cell in the database for RedCap, but embodiments of the present disclosure are not limited thereto. In response to determining that a cell does not support RedCap when the UE is searching for a PLMN, in the idle mode, in cell selection, in cell reselection, or when performing a handover, the terminal 110 may perform a cell evaluation on the next candidate cell.

[0109] Figure 7a An example of a screen of a terminal (e.g., terminal 110) for an additional power saving mode using the RedCap function is shown.

[0110] Referring to Figure 7a , the terminal 110 may provide guidance on the power saving mode (or referred to as the "low power mode") to the user through the display of the terminal 110. The display of the terminal 110 may display screen 701. The terminal 110 may display a visual object 711 for the additional power saving mode and a visual object 713 for the normal power saving mode, as well as a user notification message guiding that this additional power saving mode is available on the screen 701 of the display. The user notification message may read "When the additional power saving mode is set, based on the 5G reduced capabilities feature, when the UE operates on a 5G RAT, the additional power saving mode is applied. The network may sometimes switch the UE from 5G to LTE according to its configuration, and when on the LTE RAT, the UE switches its operating mode to the normal power saving mode (5G RedCap is not applicable)". According to an embodiment, the additional power saving mode may indicate support for the RedCap function in a 5G NR cell. According to an embodiment, the normal power saving mode may indicate that the RedCap function is not used in a 5G NR cell.

[0111] Figure 7b An example operation flow of a terminal (e.g., terminal 110) for identifying a radio access technology (RAT) according to the additional power saving mode is shown. The radio access technology (RAT) refers to the communication method between the terminal 110 and the cell of a base station (e.g., base station 120 or base station 130).

[0112] Referring to Figure 7b, in operation 751, the terminal 110 can identify an additional power saving mode in the NR RAT. Different from the normal power saving mode, the additional power saving mode requires the terminal 110 to operate in the NR RAT. In other words, the additional power saving mode can require the terminal 110 to connect to an NR cell. Since the RedCap function defined in the 5G NR standard must be supported in the additional power saving mode, the terminal 110 can identify the additional power saving mode in the NR RAT.

[0113] In operation 753, the terminal 110 can determine whether to fallback to the LTE RAT. When determining such a fallback to the LTE RAT, the terminal 110 can perform operation 755. When determining that there is no fallback to the LTE RAT, the terminal 110 can perform operation 757.

[0114] In operation 755, the terminal 110 can communicate with the LTE RAT. When the user selects the additional power saving mode (e.g., when a user input is received on the visual object 711 in Figure 7a ), the terminal 110 can switch the operation mode from the NR normal mode to the RedCap mode. Then, when a mobility command for the LTE RAT is received from the network, the terminal 110 can perform a registration process in the LTE cell. In this case, the terminal 110 can store the RedCap mode. In addition, when returning to the 5G NR cell, the terminal 110 can store information about the NR cell of the NR RAT for recovery.

[0115] In operation 757, the terminal 110 can communicate with the NR RAT.

[0116] Figure 8 An example operation flow of a terminal (e.g., the terminal 110) for switching to the RedCap mode is shown. The RedCap mode refers to an operation mode that provides power saving for the terminal 110 by specifying requirements in the NR standard. For example, in the RedCap mode, the maximum bandwidth of the terminal 110, the number of transmit antennas of the terminal 110, and the number of receive antennas of the terminal 110 can be restricted. In Figure 8 , the conditions for automatically switching to the RedCap mode are described.

[0117] Refer to Figure 8 , in operation 801, the terminal 110 can operate through the NR normal mode. The terminal 110 can access an NR cell using a 5G communication scheme. The terminal 110 can communicate with the NR cell in an operation mode other than the RedCap mode (i.e., the NR normal mode).

[0118] In operation 803, the terminal 110 may identify whether the battery level of the terminal 110 is less than a battery threshold. When the battery level of the terminal 110 is less than the battery threshold, the terminal 110 may perform operation 807. When the battery level of the terminal 110 is greater than the battery threshold, the terminal 110 may perform operation 805.

[0119] In operation 805, the terminal 110 may identify whether the temperature of the terminal 110 is greater than a temperature threshold. When the temperature of the terminal 110 is greater than the temperature threshold, the terminal 110 may perform operation 807. When the temperature of the terminal 110 is less than the temperature threshold, the terminal 110 may perform operation 801.

[0120] In operation 807, the terminal 110 may identify whether the NR serving cell supports RedCap. According to an embodiment, the terminal 110 may identify whether the NR serving cell supports RedCap based on the method illustrated in operation 503 (e.g., based on the determination of whether the intra-frequency selection information (“intraFreqReselectionRedCap” IE) is included in SIB1). When the NR serving cell supports RedCap, the terminal 110 may perform operation 809, and when the NR serving cell does not support RedCap, the terminal 110 may perform operation 811.

[0121] In operation 809, the terminal 110 may communicate in the RedCap mode.

[0122] In operation 811, the terminal 110 may communicate in the NR normal mode.

[0123] In Figure 8 the battery level condition, the temperature condition, and the RedCap support condition are described in sequence, but the embodiments of the present disclosure are not limited thereto. According to an embodiment, the terminal 110 may not perform operation 805. The terminal 110 may immediately perform operation 807 without determining the temperature condition. According to another embodiment, the terminal 110 may not perform operation 803. The terminal 110 may identify whether the temperature level condition according to operation 805 is satisfied without determining the battery level condition.

[0124] Figure 9 A signal flow for performing an emergency service based on operation mode switching is shown. Figure 9 The operation of Figure 4b may correspond to

[0125] Reference Figure 9 , in operation 901, the terminal 110 may switch the operation mode to the NR normal mode. The operation mode of the terminal 110 may be changed from the RedCap mode to the NR normal mode.

[0126] In operation 903, the terminal 110 may perform a cell access procedure. The terminal 110 may perform an access procedure (e.g., a random access procedure) to an NR cell that does not support the RedCap function (hereinafter, NR cell #1 (931)). The terminal 110 may perform an access procedure to NR cell #1 (931) to continue an ongoing emergency service. For example, NR cell #1 (931) may correspond to Figure 4b NR cell 473.

[0127] In operation 905, the terminal 110 may perform an emergency service. The terminal 110 may perform an emergency service on NR cell #1 (931) in the NR normal mode.

[0128] In operation 907, the terminal 110 may switch the operation mode to the RedCap mode. The terminal 110 may communicate in the NR normal mode on NR cell #1 (931) until the emergency service terminates. The terminal 110 may recognize the termination of the emergency service. In response to recognizing the termination of the emergency service, the terminal 110 may perform a switch of the operation mode. The operation mode of the terminal 110 may be changed from the NR normal mode to the RedCap mode.

[0129] In operation 909, the terminal 110 may identify a cell that supports RedCap. For example, the terminal 110 may identify NR cell #2 (933). According to an embodiment, the terminal 110 may identify a cell that supports RedCap (e.g., NR cell #2 (933)) based on a database storing the carrier frequencies of cells that support RedCap. Additionally, according to an embodiment, the terminal 110 may identify a cell that supports RedCap (e.g., NR cell #2 (933)) based on a frequency scan using a frequency list stored in the terminal 110. In the frequency scan, it may be determined whether each cell supports RedCap based on the system information of the corresponding cell.

[0130] In operation 911, the terminal 110 may perform a cell access procedure. The terminal 110 may perform an access procedure to the NR cell #2 (933) that supports RedCap. The terminal 110 may communicate in the RedCap mode on NR cell #2 (933). According to an embodiment, the terminal 110 may perform an access procedure to NR cell #2 (933) again through cell selection or cell reselection. According to another embodiment, the terminal 110 may send a measurement report to NR cell #1 (931) that is the current serving cell. Then, it may perform an access to NR cell #2 (933) by receiving a handover command for NR cell #2 (933) from the base station of NR cell #1 (931).

[0131] Although Figure 9NR cell #1 (931) and NR cell #2 (933) are shown respectively, but embodiments of the present disclosure are not limited thereto according to their implementation methods. According to an embodiment, the two cells may be provided by the same base station (e.g., base station 130). Alternatively, according to another embodiment, NR cell #1 (931) may be provided by a first gNB, and NR cell #2 (933) may be provided by a second gNB.

[0132] Figure 10 An example operation flow for configuring a terminal (e.g., terminal 110) in RedCap mode is shown. The RedCap mode may require restricting parameters of the physical layer of terminal 110. As the operation mode of terminal 110 changes, one or more parameters for terminal 110 may change.

[0133] Refer to Figure 10 , in operation 1001, terminal 110 may set the maximum operating bandwidth according to the RedCap mode. For example, the band of the current serving cell operating in RedCap mode may belong to FR1 of NR. According to an embodiment, terminal 110 may set the maximum operating bandwidth of terminal 110 to 20 MHz in FR1. As another example, the band of the current serving cell operating in RedCap mode may belong to FR2 of NR. According to an embodiment, terminal 110 may set the maximum operating bandwidth of terminal 110 to 100 MHz in FR2.

[0134] In operation 1003, terminal 110 may set the maximum number of receiving antennas according to the RedCap mode. The maximum number of receiving antennas may depend on the band. For example, the band of the current serving cell operating in RedCap mode may belong to FR1 of NR. According to an embodiment, in FR1, terminal 110 may set the maximum number of receiving antennas of terminal 110 to 1 or 2. As another example, the band of the current serving cell operating in RedCap mode may belong to FR2 of NR. According to an embodiment, terminal 110 may set the maximum number of receiving antennas of terminal 110 to 1 in FR2.

[0135] In operation 1005, terminal 110 may set the maximum number of downlink (DL) MIMO layers according to the RedCap mode. The maximum number of receiving antennas may depend on the band. For example, the band of the current serving cell operating in RedCap mode may belong to FR1 of NR. According to an embodiment, in FR1, terminal 110 may set the maximum number of DL MIMO layers of terminal 110 to 1 or 2. As another example, the band of the current serving cell operating in RedCap mode may belong to FR2 of NR. According to an embodiment, in FR2, terminal 110 may set the maximum number of DL MIMO layers of terminal 110 to 1.

[0136] In operation 1007, the terminal 110 may set the maximum DL modulation order according to the RedCap mode. For example, the frequency band of the current serving cell operating in the RedCap mode may belong to FR1 of NR. According to an embodiment, in FR1, the terminal 110 may set the maximum DL modulation order of the terminal 110 to 64QAM (Quadrature Amplitude Modulation). As another example, the frequency band of the current serving cell operating in the RedCap mode may belong to FR2 of NR. According to an embodiment, in FR2, the terminal 110 may set the maximum DL modulation order of the terminal 110 to 64 QAM.

[0137] In Figure 10 the settings of the RedCap mode of the terminal 110 are shown in sequence, but the embodiments of the present disclosure are not limited thereto. According to an embodiment, operations 1003 and 1005 may be performed before operation 1001. According to another embodiment, operation 1007 may be performed before operation 1005. According to another embodiment, at least one operation may be omitted.

[0138] Figure 10 The conditions shown may be defined as shown in the following table. According to an embodiment, the terminal 110 may set limits for at least one of the above conditions.

[0139] Table 4

[0140] Figure 11 An example operation flow of a terminal (e.g., the terminal 110) for identifying a cell supporting the RedCap function is shown.

[0141] Refer to Figure 11 , in operation 1101, the terminal 110 may identify a cell based on a database for RedCap. The cell may be an NR cell. The database may store information about RedCap cells. For example, the database may have a format as shown in Table 3.

[0142] In operation 1103, the terminal 110 may identify whether the identified NR cell meets a specified selection criterion. For example, the selection criterion may include a condition of the received level value (in decibels (dB)) of the identified NR cell and a condition of the cell selection quality value (in dB). For example, when the received level value is greater than zero and the cell selection quality value is greater than zero, the terminal 110 may identify that the selection criterion for the identified NR cell is met.

[0143] When the identified NR cell meets the selection criterion, the terminal 110 may perform operation 1105. When the identified NR cell does not meet the selection criterion, the terminal 110 may perform operation 1109.

[0144] In operation 1105, the terminal 110 can identify whether the identified NR cell supports RedCap. Since the identified NR cell meets the cell selection criteria, the terminal 110 can decode the master information block (MIB) and SIB1 of the NR cell. The terminal 110 can identify whether the identified NR cell supports RedCap based on the result of decoding SIB1. According to an embodiment, the terminal 110 can be based on the intra-frequency selection information included in SIB1 (e.g., "intraFreqReselectionRedCap") or RedCap configuration information (e.g., information indicating whether the cell supports half-duplex frequency division duplex (FDD) (e.g., "halfDuplexRedCap-Allowed" IE), information indicating that the cell is prohibited for RedCap UEs with one receive branch (i.e., 1Rx branch) (e.g., "cellBarredRedCapCap2Rx" IE), information indicating that the cell is prohibited for CapRed UEs with two receive branches (i.e., 2Rx branch) (e.g., "cellBarredRedCapCap2Rx" IE)) to identify whether the NR cell supports RedCap. For example, the terminal 110 can identify that the NR cell is prohibited based on at least one IE in the IE in the RedCap configuration information (e.g., "cellBarredRedCap1Rx" IE, "cellBarredRedCap2Rx" IE, or "halfDuplexRedCap-Allowed" IE). The terminal 110 can identify that the prohibited NR cell does not support the RedCap function. In addition, for example, when there is no intra-frequency selection information (e.g., "intraFreqReselectionRedCap") in SIB1, the terminal 110 can identify that the NR cell is prohibited. The terminal 110 can identify that the prohibited NR cell does not support the RedCap function.

[0145] If the identified cell supports RedCap, the terminal 110 can perform operation 1107. If the identified cell does not support RedCap, the terminal 110 can perform operation 1109.

[0146] In operation 1107, the terminal 110 can determine that a RedCap cell is identified. A RedCap cell can refer to a 5G NR cell that supports the RedCap function. The terminal 110 can use the frequency belonging to the TAC served in the database to perform a cell discovery process and identify a RedCap cell based on the cell discovery process.

[0147] In operation 1109, the terminal 110 may determine whether all frequency searches in the database have been performed. If all frequency searches in the database have been performed, the terminal 110 may perform operation 1111. When not all frequency searches in the database have been performed, the terminal 110 may perform operation 1101 again.

[0148] In operation 1111, the terminal 110 may determine that no RedCap cell has been identified. When the search for all frequencies is completed and no RedCap cell is identified, the terminal 110 may identify the frequency list stored for cell search. Then, the terminal 110 may search for the RedCap cell again by performing a frequency scan on the frequencies in the frequency list.

[0149] Reference Figure 1 、 Figure 2a 、 Figure 2b 、 Figure 3 、 Figure 4a 、 Figure 4b 、 Figure 5a 、 Figure 5b 、 Figure 6a 、 Figure 6b 、 Figure 7a 、 Figure 7b and Figures 8 to 11 , mainly describes the situation where the terminal 110 receives a handover command to an NR cell when performing an emergency service in an LTE cell. However, the embodiments of the present disclosure are not limited thereto. If the terminal 110 operating in the RedCap mode needs to access a cell that does not support RedCap of NR when performing an emergency service, the operation mode switch according to the embodiments of the present disclosure may be used. Hereinafter, reference Figure 12a and Figure 12b , other situations where it is necessary to access a cell that does not support RedCap of NR in addition to handover will be described.

[0150] Figure 12a Shows an example operation flow of a terminal (e.g., terminal 110) for performing an emergency service in non-3GPP access or flight mode.

[0151] Reference Figure 12a , in operation 1201, the terminal 110 may identify the trigger of the emergency service during non-3GPP access or flight mode. The terminal 110 may identify that the emergency service is triggered during non-3GPP access or flight mode. The terminal 110 may perform a cell search to perform the emergency service.

[0152] In operation 1203, the terminal 110 may switch the operation mode to the NR normal mode based on identifying that the NR cell does not support RedCap. The terminal 110 may identify that the NR cell does not support RedCap. The terminal 110 may identify that the NR cell does not support RedCap based on the system information of the NR cell. Although the terminal 110 supports the RedCap mode, the terminal 110 may change the priority operation mode to perform an emergency service on the NR cell.

[0153] In operation 1205, the terminal 110 may perform access to the NR cell that does not support RedCap. The terminal 110 may perform a random access procedure with the base station providing the NR cell. The terminal 110 may perform a registration procedure for the NR cell through NAS signaling with a core network entity (e.g., AMF).

[0154] In operation 1207, the terminal 110 may establish and perform an emergency service. Different from the previous handover, the terminal 110 may not be able to establish an emergency service before accessing the NR cell because it does not have a valid RRC connection such as an LTE cell. The terminal 110 may establish the triggered emergency service after accessing the NR cell. After establishing the emergency service, the terminal 110 may perform the emergency service on the NR cell. In this case, the operation mode of the terminal 110 may be the NR normal mode.

[0155] In operation 1209, the terminal 110 may switch the operation mode to the RedCap mode. The terminal 110 may operate in the NR normal mode until the emergency service terminates. When the emergency service terminates, the terminal 110 may change the operation mode. When the emergency service terminates, the terminal 110 may switch back to the RedCap mode again to save power.

[0156] In operation 1211, the terminal 110 may perform communication based on the RedCap mode in the NR cell that supports RedCap. The terminal 110 may scan for cells using the frequencies of the database for RedCap. The terminal 110 may detect the NR cell. The terminal 110 may identify whether the NR cell supports the RedCap function based on the system information about the NR cell (e.g., SIB1). According to an embodiment, the terminal 110 may identify whether the NR cell supports RedCap based on the method illustrated in operation 503 (e.g., based on the determination of whether the intra-frequency selection information ("intraFreqReselectionRedCap" IE) is included in SIB1). Then, the terminal 110 may perform a registration procedure in the detected NR cell. When the detected NR cell is registered, the terminal 110 may perform communication based on the RedCap mode.

[0157] As described above, even if the emergency service is triggered with non-3GPP access or in flight mode and the NR cell that does not support RedCap is discovered first, the terminal 110 can still perform access to the NR cell. If the terminal 110 searches for the NR cell that supports RedCap again, the emergency service can be delayed. Therefore, the operation mode switching according to the embodiments of the present disclosure enables the start time of the emergency service to be faster.

[0158] Figure 12b An example operation flow of a terminal (e.g., the terminal 110) for performing an emergency service in its idle state is shown.

[0159] Refer to Figure 12b , in operation 1251, the terminal 110 can identify the trigger of the emergency service during its idle state. The terminal 110 can identify that the emergency service is triggered in the RRC idle state rather than the RRC connected state. The terminal 110 can perform cell selection or cell reselection to perform the emergency service.

[0160] In operation 1253, the terminal 110 can switch the operation mode to the NR normal mode based on identifying that the NR cell does not support RedCap. The terminal 110 can identify the NR cell that does not support RedCap. The terminal 110 can identify that the NR cell does not support RedCap based on the system information of the NR cell. Although the terminal 110 supports the RedCap mode, the terminal 110 can change the priority operation mode to perform the emergency service on the NR cell.

[0161] In operation 1255, the terminal 110 can access the NR cell that does not support RedCap. The terminal 110 can perform a random access procedure with the base station providing the NR cell. The terminal 110 can perform a registration procedure for the NR cell through NAS signaling with a core network entity (e.g., the AMF).

[0162] In operation 1257, the terminal 110 can establish and perform the emergency service. Different from the previous handover, since the terminal 110 does not have any valid RRC connection, such as an LTE cell, the terminal 110 may not be able to establish the emergency service before accessing the NR cell. The terminal 110 can establish the triggered emergency service after accessing the NR cell. After establishing the emergency service, the terminal 110 can perform the emergency service on the NR cell. In this case, the operation mode of the terminal 110 can be the NR normal mode.

[0163] In operation 1259, the terminal 110 may switch the operation mode to the RedCap mode. The terminal 110 may operate in the NR normal mode until the emergency service terminates. When the emergency service terminates, the terminal 110 may change the operation mode. When the emergency service terminates, the terminal 110 may switch back to the RedCap mode to save power.

[0164] In operation 1261, the terminal 110 may perform communication based on the RedCap mode in an NR cell supporting RedCap. The terminal 110 may scan for cells using the frequencies of the database for RedCap. The terminal 110 may detect an NR cell. The terminal 110 may identify whether the NR cell supports the RedCap function based on the system information about the NR cell (e.g., SIB1). According to an embodiment, the terminal 110 may identify whether the NR cell supports RedCap based on the method illustrated in operation 503 (e.g., a determination based on whether frequency-internal selection information ("intraFreqReselectionRedCap" IE) is included in SIB1). Then, the terminal 110 may perform a registration process in the detected NR cell. When the detected NR cell is registered, the terminal 110 may perform communication based on the RedCap mode.

[0165] As described above, even if an emergency service is triggered in the idle state of the terminal 110 and an NR cell that does not support RedCap is first discovered, the terminal 110 may perform access to the NR cell. If the terminal 110 searches for an NR cell supporting RedCap again, the emergency service may be delayed. Therefore, the operation mode switch according to an embodiment of the present disclosure makes the start time of the emergency service faster.

[0166] Figure 13 An example in which the terminal performs an emergency service through an NR cell that does not support the RedCap function is shown.

[0167] Reference Figure 13 Referring to, the first screen 1300 shows an example of a terminal for performing an emergency service without applying an operation mode switch according to an embodiment of the present disclosure. The terminal may fallback to an LTE cell after performing communication with an NR cell in the RedCap mode. In the case where the terminal receives a handover command to an NR cell that does not support the RedCap function, while performing the emergency service in the LTE cell, the terminal may perform RRE on the LTE cell again to maintain the emergency service. Therefore, the visual object 1310 for indicating the communication scheme in the first screen 1300 may be indicated as "LTE".

[0168] The second screen 1350 shows an example of a terminal 110 for performing an emergency service when an application operation mode is switched according to an embodiment of the present disclosure. The terminal 110 may fall back to an LTE cell after performing communication with an NR cell in the RedCap mode. In a case where the terminal 110 receives a handover command to an NR cell that does not support the RedCap function, while performing an emergency service in the LTE cell, the terminal 110 may perform an operation mode switch to maintain the emergency service. The terminal 110 may change the operation mode from the RedCap mode to the NR normal mode. The terminal 110 may access an NR cell that does not support the RedCap function. The terminal 110 may operate in the NR normal mode on an NR cell that does not support the RedCap function. The terminal 110 may perform an emergency service on an NR cell that does not support the RedCap function. Accordingly, a visual object 1320 for indicating a communication scheme in the second screen 1350 may be indicated as "5G".

[0169] Figure 14 An example of a functional configuration of a terminal (e.g., the terminal 110) is shown. According to an embodiment, the terminal 110 shows a RedCap UE that supports the RedCap function.

[0170] Reference Figure 14 , the terminal 110 may include at least one processor 1403, at least one memory 1405, and at least one transceiver 1401. Hereinafter, elements will be described in the singular form, but the implementation of multiple elements or sub-elements is not excluded.

[0171] The transceiver 1401 is configured to perform a function of transmitting or receiving signals through a wireless channel. For example, the transceiver 1401 is configured to perform a conversion function between a baseband signal and a bit string according to a physical layer standard of the system. For example, during data transmission, the transceiver 1401 generates complex symbols by encoding and modulating a transmitted bit string. In addition, during data reception, the transceiver 1401 recovers a received bit string by demodulating and decoding a baseband signal. In addition, the transceiver 1401 up-converts a baseband signal to a radio frequency (RF) band signal to transmit the RF band signal through an antenna, and down-converts an RF band signal received through the antenna to a baseband signal.

[0172] To this end, the transceiver 1401 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a digital-to-analog converter (DAC), an analog-to-digital converter (ADC), etc. In addition, the transceiver 1401 may include multiple transmit / receive paths. In addition, the transceiver 1401 may include an antenna unit. The transceiver 1401 may include at least one antenna array having multiple antenna elements. In terms of hardware, the transceiver 1401 may be configured by a digital circuit and an analog circuit (e.g., a radio frequency integrated circuit (RFIC)). Here, the digital circuit and the analog circuit may be implemented as a single package. In addition, the transceiver 1401 may include multiple RF chains. The transceiver 1401 may perform beamforming. The transceiver 1401 may apply beamforming weights to signals for transmission / reception in order to allocate directivity according to the configuration of the processor 1403. According to an embodiment, the transceiver 1401 may include a radio frequency (RF) block (or RF unit).

[0173] The transceiver 1401 is configured to transmit and receive the signals as described above. Accordingly, the transceiver 1401 may be referred to as a "transmitter", a "receiver", or a "transceiver unit". According to an embodiment, the transceiver 1401 may provide an interface for communicating with other nodes in the network. That is, the transceiver 1401 may be configured to convert a bit string transmitted by the terminal 110 to another node (e.g., another access node, another base station, an upper layer node, a core network, etc.) into a physical signal, and convert a physical signal received from another node into a bit string.

[0174] The processor 1403 controls the overall operation of the terminal 110. For example, the processor 1403 records and reads data in the memory 1405. For example, the processor 1403 transmits and receives signals through the transceiver 1401. Although Figure 14 one processor is shown, embodiments of the present disclosure are not limited thereto. The terminal 110 may include at least one processor to execute the embodiments of the present disclosure. The processor 1403 may be referred to as a control unit or a control device. According to an embodiment, the processor 1403 may control the terminal 110 to execute at least one of the operations or methods according to the embodiments of the present disclosure.

[0175] The memory 1405 may store data such as basic programs, application programs, and configuration information for operating the terminal 110. The memory 1405 may store various data used by the above at least one element (e.g., the transceiver 1401 or the processor 1403). The data may include, for example, software and input or output data related thereto. The memory 1405 may include a volatile memory, a non-volatile memory, or a combination of a volatile memory and a non-volatile memory. The memory 1405 may provide the stored data according to the request of the processor 1403.

[0176] Figure 15 Shows an example of the functional configuration of a base station (e.g., base station 120 or base station 130). According to an embodiment, base station 120 may be exemplified as an eNB, and base station 130 may be exemplified as a gNB.

[0177] Referring Figure 15 , base station 120 or base station 130 may include a transceiver 1551, a processor 1553, a memory 1555, and a backhaul transceiver 1557.

[0178] The transceiver 1551 may perform functions for transmitting and receiving signals in a wired communication environment. The transceiver 1551 may include a wired interface for controlling device-to-device direct connections via a transmission medium (e.g., copper wire, optical fiber, etc.). For example, the transceiver 1551 may send an electrical signal to another device via such a copper wire, or may perform a conversion between an electrical signal and an optical signal.

[0179] The transceiver 1551 may perform functions for transmitting and receiving signals in a wireless communication environment. For example, the transceiver 1551 may perform a conversion function between a baseband signal and a bit string according to the physical layer standard of the system. For example, during data transmission, the transceiver 1551 generates complex symbols by encoding and modulating the transmission bit string. In addition, during data reception, the transceiver 1551 recovers the received bit string by demodulating and decoding the baseband signal. Additionally, the transceiver 1551 may include multiple transmit / receive paths. Furthermore, according to an embodiment, the transceiver 1551 may be connected to a core network or may be connected to other nodes (e.g., integrated access backhaul (IAB)).

[0180] As described above, the transceiver 1551 transmits and receives signals. Accordingly, all or part of the transceiver 1551 may be referred to as a "communication unit", "transmitter", "receiver", or "transceiver unit". Additionally, in the following description, terms such as "transmit" and "receive" performed via a wireless channel may be used to include the meaning of performing the above processes by the transceiver 1551.

[0181] The processor 1553 controls the overall operation of base station 120 or base station 130. The processor 1553 may be referred to as a controller or a control unit. For example, the processor 1553 sends and receives signals via the transceiver 1551 (or via the backhaul transceiver 1557). Additionally, the processor 1553 may record and read data in the memory 1555. Furthermore, the processor 1553 may perform functions of a protocol stack required by the corresponding communication standard. Although only the processor 1553 is shown in Figure 15 , according to an example of another implementation, base station 120 or base station 130 may include two or more processors.

[0182] The memory 1555 may store data for operating the base station 120 or the base station 130, such as basic programs, application programs, and configuration information. The memory 1555 may be referred to as a storage device. The memory 1555 may include a volatile memory, a non-volatile memory, or a combination of a volatile memory and a non-volatile memory. In addition, the memory 1555 provides the stored data according to the request of the processor 1553.

[0183] The base station 120 or the base station 130 may further include a backhaul transceiver 1557 to connect to a core network or another base station (e.g., the base station 130 or the base station 120). The backhaul transceiver 1557 provides an interface for communicating with other nodes in the network. That is, the backhaul transceiver 1557 may convert a bit string transmitted from the base station to another node (e.g., another access node, another base station, an upper-layer node, a core network, etc.) into a physical signal, and convert a physical signal received from other nodes into a bit string.

[0184] According to an embodiment, a method performed by a terminal in a wireless communication system may include: receiving, while performing an emergency service on a Long-Term Evolution (LTE) cell, a Radio Resource Control (RRC) message including a handover command to a New Radio (NR) cell from a serving base station. The method may include identifying whether the NR cell supports a Reduced Capability (RedCap) function based on system information about the NR cell. The method may include: in a case where the NR cell does not support the RedCap function, switching an operation mode of the terminal from a RedCap mode to an NR normal mode. The method may include: when the terminal operates in the NR normal mode, performing an emergency service on the NR cell by accessing the NR cell. The method may include: in response to termination of the emergency service, switching the operation mode of the terminal from the NR normal mode to the RedCap mode.

[0185] According to an embodiment, the system information may include System Information Block (SIB) 1. In addition, whether the NR cell supports the RedCap function is determined according to whether frequency-in selection information is included in SIB1.

[0186] According to an embodiment, the system information may include System Information Block (SIB) 1. SIB1 may include at least one of first information for indicating whether the cell supports Half-Duplex Frequency Division Duplex (FDD), second information for indicating whether the cell is prohibited for a terminal having one receive branch, and third information for indicating whether the cell is blocked for a terminal having two receive branches. Whether the NR cell supports the RedCap function may be determined based on at least one of the first information, the second information, or the third information.

[0187] According to an embodiment, the execution of an emergency service may include performing a random access procedure with a target base station that provides an NR cell. The execution of the emergency service may include performing a registration procedure with an access management function (AMF) associated with the NR cell. The execution of the emergency service may include: after the registration procedure is completed, performing the emergency service on the NR cell.

[0188] According to an embodiment, the method may further include: after switching the operation mode of the terminal from the RedCap mode to the NR normal mode, identifying a target NR cell that supports the RedCap function. The method may further include performing a random access procedure on the target NR cell.

[0189] According to an embodiment, identifying the target NR cell may include: identifying cell information from a database for the RedCap function. Identifying the target NR cell may include: identifying whether a cell searched based on the cell information supports the RedCap function. Identifying the target NR cell may include: in the case where the searched cell supports the RedCap function, determining the searched cell as the target NR cell.

[0190] According to an embodiment, identifying the target NR cell may include: obtaining a search result by searching all frequencies in the database. Identifying the target NR cell may include: based on identifying that no NR cell supporting the RedCap function is detected, obtaining a stored frequency list through the search result. Identifying the target NR cell may include: identifying the target NR cell that supports the RedCap function through a frequency scan performed based on the stored frequency list.

[0191] According to an embodiment, the method may further include operating the RedCap mode in another NR cell before performing the emergency service in the LTE cell. The method may further include storing information about the other NR cell into a database for the RedCap function.

[0192] According to an embodiment, the RRC message may include identification information for the NR cell and system information for the NR cell. The system information for the NR cell may be used to indicate whether the NR cell supports the RedCap function.

[0193] According to an embodiment, when the operating mode is the RedCap mode, the maximum bandwidth can be configured to 20 megahertz (MHz) in frequency range (FR) 1 or 100 MHz in FR2. When the operating mode is the RedCap mode, the maximum modulation order can be configured to 64 quadrature amplitude modulation (QAM). The maximum number of receive antennas for the NR normal mode is 2 or 4. The maximum number of receive antennas for the RedCap mode can be configured to be half of the maximum number of receive antennas for the NR normal mode. The maximum number of layers for the downlink multiple-input multiple-output (MIMO) in the RedCap mode can be configured to be equal to the maximum number of receive antennas for the NR normal mode.

[0194] According to an embodiment, a terminal (or device) in a wireless communication system may include at least one transceiver and at least one processor coupled to the at least one transceiver. The at least one processor may be configured to: while performing an emergency service on a Long-Term Evolution (LTE) cell, receive a radio resource control (RRC) message including a handover command to a New Radio (NR) cell from a serving base station. The at least one processor may be configured to identify whether the NR cell supports a reduced-capability (RedCap) function based on system information about the NR cell. The at least one processor may be configured to switch the operating mode of the terminal from the RedCap mode to the NR normal mode when the NR cell does not support the RedCap function. The at least one processor may be configured to: while the terminal operates in the NR normal mode, perform an emergency service on the NR cell by accessing the NR cell. The at least one processor may be configured to: in response to the termination of the emergency service, switch the operating mode of the terminal from the NR normal mode to the RedCap mode.

[0195] According to an embodiment, the system information may include System Information Block (SIB) 1. Whether the NR cell supports the RedCap function may be determined according to whether the frequency-in selection information is included in SIB1.

[0196] According to an embodiment, the system information may include System Information Block (SIB) 1. SIB1 may include at least one of first information for indicating whether the cell supports half-duplex frequency-division duplex (FDD), second information for indicating whether the cell is prohibited for a terminal with one receive branch, and third information for indicating whether the cell is blocked for a terminal with two receive branches. Whether the NR cell supports the RedCap function may be determined based on at least one of the first information, the second information, or the third information.

[0197] According to an embodiment, to perform an emergency service, at least one processor may be configured to perform a random access procedure with a target base station providing an NR cell. To perform an emergency service, at least one processor may be configured to perform a registration procedure with an access management function (AMF) associated with the NR cell. To perform an emergency service, at least one processor may be configured to perform an emergency service on the NR cell after the registration procedure is completed.

[0198] According to an embodiment, at least one processor may also be configured to: identify a target NR cell that supports the RedCap function after switching the operation mode of the terminal from the RedCap mode to the NR normal mode. At least one processor may also be configured to: perform a random access procedure on the target NR cell.

[0199] According to an embodiment, to identify a target NR cell, at least one processor may be configured to identify cell information from a database for the RedCap function. To identify a target NR cell, at least one processor may be configured to identify whether a cell searched based on the cell information supports the RedCap function. To identify a target NR cell, at least one processor may be configured to, in the case where the searched cell supports the RedCap function, determine the searched cell as the target NR cell.

[0200] According to an embodiment, to identify a target NR cell, at least one processor may be configured to obtain a search result by searching all frequencies in a database. To identify a target NR cell, at least one processor may be configured to obtain a stored frequency list based on identifying that no NR cell supporting the RedCap function is detected. To identify a target NR cell, at least one processor may be configured to identify a target NR cell supporting the RedCap function by performing a frequency scan based on the frequency list.

[0201] According to an embodiment, at least one processor may also be configured to operate in the RedCap mode in another NR cell before performing an emergency service in an LTE cell. At least one processor may also be configured to store information about the other NR cell into a database for the RedCap function.

[0202] According to an embodiment, an RRC message may include identification information for an NR cell and system information for the NR cell. The system information for the NR cell may be used to indicate whether the NR cell supports the RedCap function.

[0203] According to an embodiment, when the operation mode is the RedCap mode, the maximum bandwidth can be configured to 20 megahertz (MHz) in frequency range (FR) 1 or 100 MHz in FR2. When the operation mode is the RedCap mode, the maximum modulation order can be configured to 64 quadrature amplitude modulation (QAM). The maximum number of receive antennas for the NR normal mode can be 2 or 4. The maximum number of receive antennas for the RedCap mode can be configured to be half of the maximum number of receive antennas for the NR normal mode. The maximum number of layers for the downlink multiple-input multiple-output (MIMO) in the RedCap mode can be configured to be equal to the maximum number of receive antennas for the NR normal mode.

[0204] According to an embodiment, at least one processor is further configured to: identify an additional power saving mode when the terminal operates in a New Radio (NR) radio access technology (RAT).

[0205] According to an embodiment, at least one processor is further configured to: determine whether to fallback to a Long Term Evolution (LTE) RAT; communicate in the LTE RAT in response to determining to fallback to the LTE RAT; and communicate in the NR RAT in response to determining not to fallback to the LTE RAT.

[0206] According to an embodiment, an additional power saving mode is supported in the RedCap mode based on the terminal performing at least one of a discontinuous reception (DRX) extension operation, a bandwidth part (BWP) reduction operation, or a radio resource management (RRM) relaxation operation.

[0207] According to an embodiment, a non-transitory computer-readable medium is provided. The non-transitory computer-readable medium includes a memory storing instructions. When the instructions are executed by a processor, the instructions cause the terminal to: receive a radio resource control (RRC) message including a handover command to a New Radio (NR) cell from a serving base station while performing an emergency service on a Long Term Evolution (LTE) cell; identify whether the NR cell supports a reduced-capability (RedCap) function based on system information about the NR cell; switch the operation mode of the terminal from the RedCap mode to the NR normal mode when the NR cell does not support the RedCap function; perform the emergency service on the NR cell by accessing the NR cell while the terminal operates in the NR normal mode; and switch the operation mode of the terminal from the NR normal mode to the RedCap mode in response to the termination of the emergency service.

[0208] An electronic device and method according to an embodiment of the present disclosure can access an NR cell without performing RRE with an LTE cell, so that even when receiving a handover command to an NR cell that does not support the RedCap function, emergency services can be performed in the normal mode rather than the RedCap mode, enabling the system to reduce service interruption and improve communication performance.

[0209] The effects obtainable from the present disclosure are not limited to the above effects, and those of ordinary skill in the art to which the present disclosure pertains will clearly understand any other effects not mentioned herein based on the above description.

[0210] Various embodiments described herein can be implemented as software including one or more instructions stored in a machine-readable storage medium. For example, a processor of a machine can call at least one of the one or more instructions stored in the storage medium and execute it under the control of the processor with or without using one or more other components. This allows the machine to perform at least one function according to the at least one called instruction. The one or more instructions can include code generated by a compiler or code executable by an interpreter. The machine-readable storage medium can be provided in the form of a non-transitory storage medium. Herein, the term "non-transitory" merely means that the storage medium is a tangible device and does not include signals (e.g., electromagnetic waves), but this term does not distinguish between data being semi-permanently stored in the storage medium and data being temporarily stored in the storage medium.

[0211] According to an example, a method according to various embodiments of the present disclosure can be included and provided in a computer program product. The computer program product can be traded as a product between a seller and a buyer. The computer program product can be distributed in the form of a machine-readable storage medium (e.g., a compact disc read-only memory (CD-ROM)), or distributed online via an application store (e.g., PlayStore TM ) (e.g., downloaded or uploaded), or directly distributed between two user devices (e.g., smart phones). If distributed online, at least a part of the computer program product can be temporarily generated or at least temporarily stored in a machine-readable storage medium, such as the memory of a manufacturer server, the server of an application store, or a relay server.

[0212] According to various embodiments of the present disclosure, each of the above components (e.g., modules or programs) may include a single entity or multiple entities, and some of the multiple entities may be separately provided in different components. According to various embodiments of the present disclosure, one or more of the above components may be omitted, or one or more other components may be added. Alternatively or additionally, multiple components (e.g., modules or programs) may be integrated into a single component. In this case, according to various embodiments of the present disclosure, the integrated component may still perform one or more functions of each of the multiple components in the same or similar manner as performed by the corresponding component among the multiple components before integration. According to various embodiments of the present disclosure, operations performed by a module, a program, or another component may be executed sequentially, in parallel, repeatedly, or heuristically, or one or more operations may be executed in a different order or omitted, or one or more other operations may be added.

[0213] The method according to various embodiments described in the claims and / or the specification of the present disclosure may be implemented in the form of hardware, software, or a combination of hardware and software.

[0214] When implemented by software, a computer-readable storage medium storing one or more programs (software modules) may be provided. One or more programs stored in such a computer-readable storage medium are configured to be executed by one or more processors in an electronic device. The one or more programs include instructions for causing the electronic device to execute the method according to the embodiments described in the claims or the specification of the present disclosure.

[0215] Such a program (e.g., software module, software) may be stored in a random access memory, a non-volatile memory including flash memory, a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), a magnetic disk storage device, a compact disc-ROM (CD-ROM), a digital versatile disc (DVD), other types of optical storage devices, or a magnetic tape cartridge. Alternatively, it may be stored in a memory configured with a combination of some or all of the above. Additionally, the corresponding constituent memories may be provided in a plurality of numbers.

[0216] Furthermore, the program may be stored in an attachable storage device, which may be accessed via a communication network (e.g., the Internet, an intranet, a local area network (LAN), a wide area network (WAN), or a storage area network (SAN)) or a communication network configured with a combination thereof. Such a storage device may be accessed through an external port by a device that executes the embodiments of the present disclosure. Additionally, a separate storage device on the communication network may be accessed by a device that executes the embodiments of the present disclosure.

[0217] Although the present disclosure has been shown and described with reference to various embodiments thereof, those skilled in the art will understand that various changes in form and detail may be made herein without departing from the scope of the present disclosure as defined by the appended claims and their equivalents.

Claims

1. A method performed by a terminal, the method comprises: while performing an emergency service on a Long Term Evolution (LTE) cell, receiving a Radio Resource Control (RRC) message including a handover command to a New Radio (NR) cell from a serving base station; identifying, based on system information about the NR cell, whether the NR cell supports the Reduced Capability (RedCap) function; in a case where the NR cell does not support the RedCap function, switching an operation mode of the terminal from a RedCap mode to an NR normal mode; when the terminal operates in the NR normal mode, performing the emergency service on the NR cell by accessing the NR cell; and in response to termination of the emergency service, switching the operation mode of the terminal from the NR normal mode to the RedCap mode.

2. The method according to claim 1, wherein, the system information includes System Information Block (SIB) 1, and wherein whether the NR cell supports the RedCap function is determined according to whether frequency-in selection information is included in the SIB1.

3. The method according to claim 1, wherein, the system information includes System Information Block (SIB) 1, wherein the SIB1 includes at least one of first information for indicating whether the cell supports Half-Duplex Frequency Division Duplexing (FDD), second information for indicating whether the cell is prohibited for a terminal with one receive branch, and third information for indicating whether the cell is blocked for a terminal with two receive branches, and wherein whether the NR cell supports the RedCap function is determined based on at least one of the first information, the second information, or the third information.

4. The method according to claim 1, wherein, performing the emergency service includes: performing a random access procedure with a target base station providing the NR cell; performing a registration procedure with an Access Management Function (AMF) associated with the NR cell; and after completion of the registration procedure, performing the emergency service on the NR cell.

5. The method according to claim 1, the method further comprises: after the operation mode of the terminal is switched from the RedCap mode to the NR normal mode, identifying a target NR cell that supports the RedCap function; and performing a random access procedure on the target NR cell.

6. The method according to claim 5, wherein, identifying the target NR cell includes: identifying cell information from a database for the RedCap function; identifying whether a cell searched based on the cell information supports the RedCap function; and in a case where a searched cell supports the RedCap function, determining the searched cell as the target NR cell.

7. The method according to claim 6, wherein, identifying the target NR cell includes: obtaining a search result by searching all frequencies in the database; obtaining a stored frequency list based on identifying that no NR cell supporting the RedCap function is detected; and Identify the cell that supports the RedCap function as the target NR cell by performing a frequency scan according to the stored frequency list.

8. The method according to claim 1, the method further includes: Before performing the emergency service in the LTE cell, operate the RedCap mode in another NR cell; and Store the information about the other NR cell into the database for the RedCap function.

9. The method according to claim 1, wherein, The RRC message includes the identification information for the NR cell and the system information for the NR cell, and wherein, the system information for the NR cell is used to indicate whether the NR cell supports the RedCap function.

10. The method according to claim 1, wherein, When the operating mode is the RedCap mode, the maximum bandwidth is configured as 20 megahertz (MHz) in frequency range FR1 or 100 MHz in FR2, wherein, when the operating mode is the RedCap mode, the maximum modulation order is configured as 64 quadrature amplitude modulation (QAM), wherein, the maximum number of receiving antennas for the NR normal mode is 2 or 4, wherein, the maximum number of receiving antennas for the RedCap mode is configured to be half of the maximum number of receiving antennas for the NR normal mode, and wherein, the maximum number of layers of the downlink multiple-input multiple-output (MIMO) for the RedCap mode is configured to be equal to the maximum number of receiving antennas for the NR normal mode.

11. A terminal in a wireless communication system, the terminal includes: At least one transceiver; and At least one processor, the at least one processor is coupled to the at least one transceiver, wherein, the at least one processor is configured to: While performing an emergency service on a Long-Term Evolution (LTE) cell, receive a Radio Resource Control (RRC) message including a handover command to a New Radio (NR) cell from a serving base station, Based on the system information about the NR cell, identify whether the NR cell supports the Reduced-Capability (RedCap) function, If the NR cell does not support the RedCap function, switch the operating mode of the terminal from the RedCap mode to the NR normal mode, When the terminal operates in the NR normal mode, perform the emergency service on the NR cell by accessing the NR cell, and In response to the termination of the emergency service, switch the operating mode of the terminal from the NR normal mode to the RedCap mode.

12. The terminal according to claim 11, wherein, The system information includes System Information Block (SIB) 1, and wherein, whether the NR cell supports the RedCap function is determined according to whether the SIB1 includes intra-frequency selection information.

13. The terminal according to claim 11, wherein, The system information includes System Information Block (SIB) 1, Wherein, the SIB1 includes at least one of first information for indicating whether the cell supports half-duplex frequency division duplex (FDD), second information for indicating whether the cell is prohibited for a terminal with one receive branch, and third information for indicating whether the cell is blocked for a terminal with two receive branches, and wherein whether the NR cell supports the RedCap function is determined based on at least one of the first information, the second information, or the third information.

14. The terminal according to claim 11, wherein, to perform the emergency service, the at least one processor is configured to execute the method according to any one of claims 4 to 10.

15. A non-transitory computer-readable medium, the non-transitory computer-readable medium includes a memory that stores instructions, wherein, when the instructions are executed by a processor, the instructions cause the terminal to: while performing an emergency service on a Long-Term Evolution (LTE) cell, receive a Radio Resource Control (RRC) message including a handover command to a New Radio (NR) cell from a serving base station, identify whether the NR cell supports a Reduced-Capability (RedCap) function based on system information about the NR cell, in a case where the NR cell does not support the RedCap function, switch an operation mode of the terminal from a RedCap mode to an NR normal mode, while the terminal operates in the NR normal mode, perform the emergency service on the NR cell by accessing the NR cell, and in response to termination of the emergency service, switch the operation mode of the terminal from the NR normal mode to the RedCap mode.

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