Method by which terminal resumes RRC connection with base station in next generation energy-saving mobile communication system, and apparatus

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting higher data transmission rates. According to one embodiment of the present invention, an operation method of a base station supporting a synchronization cell (sync cell) and a data cell in a wireless communication system is disclosed. The method of a base station may comprise the steps of: transmitting, to a terminal, a radio resource control (RRC) connection release message including a synchronization cell list for at least one synchronization cell; transmitting, to the terminal, a synchronization cell synchronization signal block (SSB) or a synchronization cell system information block (SIB) through the synchronization cell; and activating one of data cells having received a wake-up signal from the terminal, and transmitting a data cell SSB or a data cell SIB to the terminal through the activated data cell.

Description

Method and device for resuming RRC connection between a terminal and a base station in a next-generation energy-saving mobile communication system

[0001] The present invention relates to a network configuration capable of saving energy in a next-generation mobile communication system and a method for resuming an RRC connection accordingly.

[0002] 5G mobile communication technology defines a wide frequency band to enable fast transmission speeds and new services, and can be implemented not only in the sub-6GHz frequency band such as 3.5 gigahertz (3.5GHz), but also in the ultra-high frequency band called millimeter wave (mmWave) such as 28GHz and 39GHz ('Above 6GHz'). In addition, for 6G mobile communication technology, which is called the system after 5G communication (Beyond 5G), implementation in the terahertz band (for example, the 3 terahertz (3THz) band at 95GHz) is being considered to achieve a transmission speed that is 50 times faster than 5G mobile communication technology and an ultra-low latency time that is reduced to one-tenth.

[0003] In the early stages of 5G mobile communication technology, the goal is to support services and satisfy performance requirements for enhanced Mobile Broadband (eMBB), Ultra-Reliable Low-Latency Communications (URLLC), and massive Machine-Type Communications (mMTC). These include beamforming and massive MIMO to mitigate path loss of radio waves in ultra-high frequency bands and increase the transmission distance of radio waves, support for various numerologies (such as operation of multiple subcarrier intervals) and dynamic operation of slot formats for efficient use of ultra-high frequency resources, initial access technology to support multi-beam transmission and wideband, definition and operation of BWP (Bidth Part), new channel coding methods such as LDPC (Low Density Parity Check) codes for large-capacity data transmission and Polar Code for reliable transmission of control information, and L2 pre-processing (L2). Standardization has been made for network slicing, which provides dedicated networks specialized for specific services, and pre-processing.

[0004] Currently, discussions are underway to improve and enhance the initial 5G mobile communication technology in consideration of the services that 5G mobile communication technology was intended to support, and physical layer standardization is in progress for technologies such as V2X (Vehicle-to-Everything) to help autonomous vehicles make driving decisions and increase user convenience based on their own location and status information transmitted by vehicles, NR-U (New Radio Unlicensed) for the purpose of system operation that complies with various regulatory requirements in unlicensed bands, NR terminal low power consumption technology (UE Power Saving), Non-Terrestrial Network (NTN), which is direct terminal-satellite communication to secure coverage in areas where communication with terrestrial networks is impossible, and Positioning.

[0005] In addition, standardization of wireless interface architecture / protocols is in progress for technologies such as intelligent factories (Industrial Internet of Things, IIoT) to support new services through linkage and convergence with other industries, Integrated Access and Backhaul (IAB) that provides nodes for expanding network service areas by integrating wireless backhaul links and access links, Mobility Enhancement technology including Conditional Handover and Dual Active Protocol Stack (DAPS) handover, and 2-step random access (2-step RACH for NR) that simplifies random access procedures. Standardization is also in progress for system architecture / services such as 5G baseline architecture (e.g., Service-based Architecture, Service-based Interface) for grafting Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and Mobile Edge Computing (MEC) that provides services based on the location of the terminal.

[0006] Once these 5G mobile communication systems are commercialized, an explosive increase in connected devices will be connected to the communication network, necessitating enhanced functionality and performance of 5G mobile communication systems and integrated operation of these connected devices. To this end, new research will be conducted on improving 5G performance and reducing complexity, supporting AI services, supporting metaverse services, and drone communications by utilizing eXtended Reality (XR), Artificial Intelligence (AI), and Machine Learning (ML) to efficiently support Augmented Reality (AR), Virtual Reality (VR), and Mixed Reality (MR).

[0007] In addition, the development of these 5G mobile communication systems includes new waveforms to ensure coverage in the terahertz band of 6G mobile communication technology, multi-antenna transmission technologies such as Full Dimensional MIMO (FD-MIMO), Array Antenna, and Large Scale Antenna, metamaterial-based lenses and antennas to improve the coverage of terahertz band signals, high-dimensional spatial multiplexing technology using Orbital Angular Momentum (OAM), Reconfigurable Intelligent Surface (RIS) technology, as well as full duplex technology to improve the frequency efficiency and system network of 6G mobile communication technology, satellite, AI (Artificial Intelligence) from the design stage and AI-based communication technology that realizes system optimization by internalizing end-to-end AI support functions, and ultra-high-performance communication and computing resources to provide services with complexity that exceeds the limits of terminal computing capabilities. It can serve as a basis for the development of next-generation distributed computing technologies that can be realized by utilizing them.

[0008] The purpose of the present invention is to provide a network structure for a mobile communication system for energy saving.

[0009] In addition, the present invention aims to provide a method for performing RRC connection resumption between a terminal and a base station on a network for a mobile communication system for energy saving.

[0010] According to one embodiment of the present invention, an operating method of a base station supporting a sync cell and a data cell in a wireless communication system is disclosed. The method of the base station may include the steps of: transmitting, to a terminal, an RRC (radio resource control) connection release message including a synchronization cell list for at least one synchronization cell; transmitting, to the terminal, a synchronization cell SSB (synchronization signal block) or a synchronization cell SIB (system information block) through the synchronization cell; and activating one of data cells that has received a wake-up signal from the terminal, and transmitting, to the terminal, the data cell SSB or the data cell SIB through the activated data cell.

[0011] The above synchronization cell is a cell that always operates in an active state and supports a paging function for a terminal, and the above data cell may be a cell that is activated upon receiving a wake-up signal from the terminal and does not support a paging function for the terminal.

[0012] The above RRC connection release message may additionally include data cell lists associated with each synchronization cell included in the synchronization cell list.

[0013] The RRC connection release message includes a list of data area codes set for each synchronization cell included in the synchronization cell list, and the data area codes may be associated with at least one data cell.

[0014] According to another embodiment of the present invention, a method of a terminal operating in a wireless communication system is disclosed. The method of the terminal may include the steps of: receiving an RRC (radio resource control) connection release message including a synchronization cell list for at least one synchronization cell from a data cell on which an RRC connection has been performed; transitioning to an RRC inactive mode; receiving a synchronization cell synchronization signal block (SSB) or a synchronization cell system information block (SIB) from the synchronization cell; performing a selection procedure or a reselection procedure for a synchronization cell based on the synchronization cell SSB or the synchronization cell SIB; transmitting a wake-up signal to at least one data cell associated with the synchronization cell; and receiving a data cell SSB or a data cell SIB from at least one of the data cells that have received the wake-up signal.

[0015] The method of the terminal may further include the step of: starting a timer for searching for a data cell after transitioning to the RRC inactive mode; and, if a data cell is selected before the timer expires, stopping the timer and initiating an RRC connection resumption procedure for the selected data cell.

[0016] According to at least some of the various embodiments of the present invention, a network is provided in which sync cells and data cells operate separately, and sync cells that are always powered on and data cells that are powered on and operate only when necessary are compositely arranged, so that energy can be saved on the base station side.

[0017] According to at least some of the various embodiments of the present invention, a terminal may perform RRC connection resumption based on a timer and select an optimal data cell accordingly.

[0018] FIG. 1a is a diagram illustrating the structure of an LTE system according to an embodiment of the present invention.

[0019] FIG. 1b is a diagram illustrating a wireless protocol structure in an LTE system according to an embodiment of the present invention.

[0020] FIG. 1c is a diagram illustrating the structure of a next-generation mobile communication system according to an embodiment of the present invention.

[0021] FIG. 1d is a diagram illustrating a wireless protocol structure of a next-generation mobile communication system according to an embodiment of the present invention.

[0022] FIG. 1e is a flowchart illustrating a process in which a terminal performs an RRC connection resume procedure with a base station according to an embodiment of the present invention.

[0023] FIG. 1f is a diagram illustrating a next-generation mobile communication system structure that supports network energy saving according to an embodiment of the present invention.

[0024] FIG. 1g is a diagram illustrating cells that support network energy saving according to an embodiment of the present invention.

[0025] FIG. 1h is a flowchart illustrating a process in which a terminal performs an RRC connection resume procedure with a data cell in a next-generation mobile communication system supporting network energy saving according to an embodiment of the present invention.

[0026] FIG. 1i is a flowchart illustrating a process in which a terminal performs an RRC connection resume procedure with a data cell in a next-generation mobile communication system supporting network energy saving according to an embodiment of the present invention.

[0027] FIG. 1j is a block diagram illustrating the internal structure of a terminal according to an embodiment of the present invention.

[0028] FIG. 1k is a block diagram showing the configuration of an NR base station according to an embodiment of the present invention.

[0029] The operating principles of the present invention will be described in detail below with reference to the attached drawings. In the following description of the present invention, detailed descriptions of known functions or components will be omitted if they are deemed to unnecessarily obscure the gist of the invention. Furthermore, the terms described below are defined based on their functions in the present invention and may vary depending on the intentions or practices of the user or operator. Therefore, their definitions should be based on the overall content of this specification.

[0030] In the following description of the present invention, detailed descriptions of known functions or configurations will be omitted if they are deemed to unnecessarily obscure the gist of the present invention. Hereinafter, embodiments of the present invention will be described with reference to the attached drawings.

[0031] The terms used in the following description to identify connection nodes, terms referring to network entities, terms referring to messages, terms referring to interfaces between network entities, and terms referring to various identification information are provided for convenience of explanation. Therefore, the present invention is not limited to the terms described below, and other terms referring to objects with equivalent technical meanings may be used.

[0032] For convenience of explanation, the present invention uses terms and names defined in the 3rd Generation Partnership Project Long Term Evolution (3GPP) LTE standard. However, the present invention is not limited to the above terms and names, and can be equally applied to systems that comply with other standards, such as NR (New Radio). In the present invention, eNB may be used interchangeably with gNB for convenience of explanation. That is, a base station described as eNB may represent a gNB.

[0033] FIG. 1a is a diagram illustrating the structure of an LTE system according to an embodiment of the present invention.

[0034] Referring to FIG. 1a, as illustrated, the wireless access network of the LTE system is composed of next-generation base stations (Evolved Node Bs, hereinafter referred to as ENBs, Node Bs or base stations) (1a-05, 1a-10, 1a-15, 1a-20), an MME (1a-25, Mobility Management Entity) and an S-GW (1a-30, Serving-Gateway). A user equipment (UE or terminal) (1a-35) accesses an external network through the ENBs (1a-05 to 1a-20) and the S-GW (1a-30).

[0035] In Fig. 1a, ENBs (1a-05 to 1a-20) correspond to the existing Node B of the UMTS system. ENBs are connected to UEs (1a-35) via a wireless channel and perform a more complex role than the existing Node B. In the LTE system, all user traffic, including real-time services such as VoIP (Voice over IP) via the Internet Protocol, is serviced through a shared channel. Therefore, a device that collects status information such as the buffer status of UEs, available transmission power status, and channel status and performs scheduling is required, and this is handled by the ENBs (1a-05 to 1a-20). One ENB typically controls multiple cells. For example, in order to implement a transmission rate of 100 Mbps, the LTE system uses, for example, orthogonal frequency division multiplexing (OFDM) as a wireless access technology in a 20 MHz bandwidth. In addition, it applies Adaptive Modulation & Coding (AMC) method that determines modulation scheme and channel coding rate according to the channel condition of the terminal. S-GW (1a-30) is a device that provides data bearers and creates or removes data bearers according to the control of MME (1a-25). MME is a device that is responsible for mobility management function for terminals as well as various control functions and is connected to multiple base stations.

[0036] FIG. 1b is a diagram illustrating a wireless protocol structure in an LTE system according to an embodiment of the present invention.

[0037] Referring to Figure 1b, the wireless protocol of the LTE system consists of PDCP (Packet Data Convergence Protocol 1b-05, 1b-40), RLC (Radio Link Control 1b-10, 1b-35), and MAC (Medium Access Control 1b-15, 1b-30) in the terminal and ENB, respectively. PDCP (Packet Data Convergence Protocol) (1b-05, 1b-40) is responsible for operations such as IP header compression / decompression. The main functions of PDCP are summarized as follows.

[0038] - Header compression and decompression (ROHC only)

[0039] - User data transfer function

[0040] - In-sequence delivery of upper layer PDUs at PDCP re-establishment procedure for RLC AM

[0041] - Order reordering function (For split bearers in DC (only support for RLC AM): PDCP PDU routing for transmission and PDCP PDU reordering for reception)

[0042] - Duplicate detection function (Duplicate detection of lower layer SDUs at PDCP re-establishment procedure for RLC AM)

[0043] - Retransmission function (Retransmission of PDCP SDUs at handover and, for split bearers in DC, of ​​PDCP PDUs at PDCP data-recovery procedure, for RLC AM)

[0044] - Encryption and decryption functions (Ciphering and deciphering)

[0045] - Timer-based SDU discard in uplink.

[0046] Radio Link Control (RLC) (1b-10, 1b-35) reconfigures PDCP PDUs (Packet Data Units) to an appropriate size and performs ARQ operations, etc. The main functions of RLC are summarized as follows.

[0047] - Data transfer function (Transfer of upper layer PDUs)

[0048] - ARQ function (Error Correction through ARQ (only for AM data transfer))

[0049] - Concatenation, segmentation and reassembly of RLC SDUs (only for UM and AM data transfer)

[0050] - Re-segmentation of RLC data PDUs (only for AM data transfer)

[0051] - Reordering of RLC data PDUs (only for UM and AM data transfer)

[0052] - Duplicate detection (only for UM and AM data transfer)

[0053] - Error detection function (Protocol error detection (only for AM data transfer))

[0054] - RLC SDU discard function (RLC SDU discard (only for UM and AM data transfer))

[0055] - RLC re-establishment function

[0056] MAC (1b-15, 1b-30) connects to multiple RLC layer devices configured in a single terminal, and multiplexes RLC PDUs into MAC PDUs and demultiplexes RLC PDUs from MAC PDUs. The main functions of MAC are summarized as follows.

[0057] - Mapping function (Mapping between logical channels and transport channels)

[0058] - Multiplexing and demultiplexing function (Multiplexing / demultiplexing of MAC SDUs belonging to one or different logical channels into / from transport blocks (TB) delivered to / from the physical layer on transport channels)

[0059] - Scheduling information reporting function

[0060] - HARQ function (Error correction through HARQ)

[0061] - Priority handling between logical channels of one UE

[0062] - Priority handling between UEs by means of dynamic scheduling

[0063] - MBMS service identification function

[0064] - Transport format selection function

[0065] - Padding function

[0066] The physical layer (1b-20, 1b-25) performs the operation of channel coding and modulating upper layer data, converting it into OFDM symbols and transmitting it over a wireless channel, or demodulating and channel decoding OFDM symbols received over a wireless channel and transmitting them to the upper layer.

[0067] FIG. 1c is a diagram illustrating the structure of a next-generation mobile communication system according to an embodiment of the present invention.

[0068] Referring to FIG. 1c, as illustrated, a wireless access network of a next-generation mobile communication system (hereinafter referred to as NR or 5g) is composed of a next-generation base station (New Radio Node B, hereinafter referred to as NR gNB or NR base station) (1c-10) and an NR CN (1c-05, New Radio Core Network). A user terminal (New Radio User Equipment, hereinafter referred to as NR UE or terminal) (1c-15) accesses an external network through the NR gNB (1c-10) and the NR CN (1c-05).

[0069] In Fig. 1c, the NR gNB (1c-10) corresponds to the eNB (Evolved Node B) of the existing LTE system. The NR gNB is connected to the NR UE (1c-15) via a wireless channel and can provide a service that is superior to the existing Node B. In the next-generation mobile communication system, all user traffic is serviced through a shared channel, so a device that collects status information such as the buffer status of UEs, available transmission power status, and channel status and performs scheduling is required, and the NR gNB (1c-10) is in charge of this. One NR gNB typically controls multiple cells. NR technology can have a bandwidth higher than the existing maximum bandwidth in order to implement ultra-high-speed data transmission compared to the current LTE, and NR technology can additionally incorporate beamforming technology by using Orthogonal Frequency Division Multiplexing (OFDM) as a wireless access technology. In addition, it applies the Adaptive Modulation & Coding (AMC) method that determines the modulation scheme and channel coding rate according to the channel status of the terminal. NR CN (1c-05) performs functions such as mobility support, bearer setup, and QoS setup. NR CN (1c-05) is a device that is responsible for various control functions as well as mobility management functions for the terminal and is connected to multiple base stations. In addition, the next-generation mobile communication system can also be linked with the existing LTE system, and NR CN (1c-05) is connected to MME (1c-25) through a network interface. MME is connected to the existing base station, eNB (1c-30).

[0070] FIG. 1d is a diagram illustrating a wireless protocol structure of a next-generation mobile communication system according to an embodiment of the present invention.

[0071] Figure 1d is a diagram showing a wireless protocol structure of a next-generation mobile communication system to which the present invention can be applied.

[0072] Referring to FIG. 1d, the wireless protocol of the next-generation mobile communication system consists of NR SDAP (1d-01, 1d-45), NR PDCP (1d-05, 1d-40), NR RLC (1d-10, 1d-35), and NR MAC (1d-15, 1d-30) in the terminal and NR base station, respectively.

[0073] Key features of NR SDAP (1d-01, 1d-45) may include some of the following:

[0074] - Transfer of user plane data

[0075] - Mapping function between QoS flow and data bearer for both DL and UL

[0076] - QoS flow ID marking function for uplink and downlink (marking QoS flow ID in both DL and UL packets)

[0077] - Ability to map relective QoS flow to data bearer for uplink SDAP PDUs (reflective QoS flow to DRB mapping for the UL SDAP PDUs).

[0078] For the above SDAP layer device, the terminal can be configured by an RRC message for each PDCP layer device, each bearer, or each logical channel, whether to use the header of the SDAP layer device or whether to use the function of the SDAP layer device. When the SDAP header is configured, the terminal can be instructed to update or reset the mapping information for the QoS flow and data bearer of the uplink and downlink through the NAS QoS reflection configuration 1-bit indicator (NAS reflective QoS) and the AS QoS reflection configuration 1-bit indicator (AS reflective QoS) of the SDAP header. The SDAP header can include QoS flow ID information indicating QoS. The QoS information can be used as data processing priority, scheduling information, etc. to support a smooth service.

[0079] The main functions of NR PDCP (1d-05, 1d-40) may include some of the following functions:

[0080] - Header compression and decompression (ROHC only)

[0081] - User data transfer function

[0082] - In-sequence delivery of upper layer PDUs

[0083] - Out-of-sequence delivery of upper layer PDUs

[0084] - PDCP PDU reordering for reception

[0085] - Duplicate detection of lower layer SDUs

[0086] - Retransmission function (Retransmission of PDCP SDUs)

[0087] - Encryption and decryption functions (Ciphering and deciphering)

[0088] - Timer-based SDU discard in uplink.

[0089] The reordering function of the NR PDCP device mentioned above may refer to a function of reordering PDCP PDUs received from a lower layer in order based on the PDCP SN (sequence number). This reordering function may include a function of transmitting data to an upper layer in the reordered order, or alternatively, a function of transmitting data directly without considering the order. In addition, this reordering function may include a function of recording lost PDCP PDUs by reordering the order, a function of reporting a status of lost PDCP PDUs to the transmitting side, or a function of requesting retransmission of lost PDCP PDUs.

[0090] The main features of NR RLC(1d-10, 1d-35) may include some of the following:

[0091] - Data transfer function (Transfer of upper layer PDUs)

[0092] - In-sequence delivery of upper layer PDUs

[0093] - Out-of-sequence delivery of upper layer PDUs

[0094] - ARQ function (Error Correction through ARQ)

[0095] - Concatenation, segmentation and reassembly of RLC SDUs

[0096] - Re-segmentation of RLC data PDUs

[0097] - Reordering of RLC data PDUs

[0098] - Duplicate detection function

[0099] - Protocol error detection

[0100] - RLC SDU discard function

[0101] - RLC re-establishment function

[0102] The in-sequence delivery function of the NR RLC device above refers to the function of sequentially transmitting RLC SDUs received from the lower layer to the upper layer, and may include the function of reassembling and transmitting when an original RLC SDU is divided into multiple RLC SDUs and received, the function of rearranging the received RLC PDUs based on the RLC SN (sequence number) or PDCP SN (sequence number), the function of recording lost RLC PDUs by rearranging the order, the function of reporting the status of lost RLC PDUs to the transmitting side, the function of requesting retransmission of lost RLC PDUs, the function of sequentially transmitting only the RLC SDUs up to the lost RLC SDU to the upper layer in the case of a lost RLC SDU, or the function of sequentially transmitting all RLC SDUs received before the timer starts to the upper layer in the case of a lost RLC SDU if a predetermined timer has expired, or the function of sequentially transmitting all RLC SDUs received before the timer starts to the upper layer in the case of a lost RLC SDU if a predetermined timer has expired, or the function of sequentially transmitting all RLC SDUs received up to the present ... It may include a function to sequentially deliver all received RLC SDUs to the upper layer. In addition, NR RLC (1d-10, 1d-35) may process the RLC PDUs in the order they are received (in the order of arrival, regardless of the order of the sequence number) and deliver them to the PDCP device out of order (out-of-sequence delivery). In case of segments, it may receive segments stored in a buffer or to be received later, reconstruct them into a single complete RLC PDU, process them, and deliver them to the PDCP device. The NR RLC layer may not include a concatenation function, and the function may be performed in the NR MAC layer or replaced with a multiplexing function of the NR MAC layer.

[0103] The out-of-sequence delivery function of the NR RLC device mentioned above may mean a function of directly delivering RLC SDUs received from a lower layer to an upper layer regardless of the order, and may include a function of reassembling and delivering RLC SDUs when an original RLC SDU is received divided into multiple RLC SDUs, and may include a function of storing and arranging the RLC SN or PDCP SN of received RLC PDUs to record lost RLC PDUs.

[0104] NR MAC (1d-15, 1d-30) can be connected to multiple NR RLC layer devices configured in one terminal, and the main functions of NR MAC can include some of the following functions.

[0105] - Mapping function (Mapping between logical channels and transport channels)

[0106] - Multiplexing / demultiplexing of MAC SDUs

[0107] - Scheduling information reporting function

[0108] - HARQ function (Error correction through HARQ)

[0109] - Priority handling between logical channels of one UE

[0110] - Priority handling between UEs by means of dynamic scheduling

[0111] - MBMS service identification function

[0112] - Transport format selection function

[0113] - Padding function

[0114] The NR PHY layer (1d-20, 1d-25) can perform operations such as channel coding and modulating upper layer data, converting it into OFDM symbols and transmitting it through a wireless channel, or demodulating and channel decoding OFDM symbols received through a wireless channel and transmitting them to a higher layer.

[0115] FIG. 1e is a flowchart illustrating a process in which a terminal performs an RRC connection resume procedure with a base station according to an embodiment of the present invention.

[0116] Referring to FIG. 1e, the terminal (1e-01) can operate in RRC connection mode (RRC_CONNECTED) by establishing an RRC connection with the base station (1e-02) (1e-03).

[0117] At step 1e-05, the base station (1e-02) may transmit an RRC connection release message (RRCRelease) containing suspension configuration information (suspendConfig) to the terminal (1e-01) to transition the terminal from RRC connected mode to RRC inactive mode (RRC_INACTIVE). The suspension configuration information may include at least one of the following:

[0118] - Full Terminal Resumption Identifier (fullI-RNTI)

[0119] ■ An identifier used to identify a suspended UE context of a UE in RRC_INACTIVE of an RRC inactive mode terminal (1e-01), and may be composed of 40 bits according to one embodiment of the present invention.

[0120] ■ The base station (1e-02) can use the above identifier when transmitting a paging message to an RRC deactivation mode terminal (1e-01). For example, the base station can store a paging record (PagingRecord) with a paging terminal identifier (PagingUE-Identity) set to the above identifier in a paging message and transmit it to the terminal.

[0121] ■ The RRC deactivation mode terminal (1e-01) can use the identifier when performing an RRC connection resumption procedure with the base station (1e-02). For example, the terminal can transmit an RRC connection resumption request message 1 (RRCResumeRequest1) including the identifier to the base station signaling the useFullResumeId field.

[0122] - Segmented terminal connection resumption identifier (shortI-RNTI)

[0123] ■ An identifier used to identify a reserved terminal context of an RRC inactive mode terminal (1e-01), which may be composed of 24 bits according to one embodiment of the present invention. That is, a segmented terminal connection resumption identifier may be composed of fewer bits than a complete terminal resumption identifier.

[0124] ■ The RRC deactivation mode terminal (1e-01) can use the identifier when performing an RRC connection resumption procedure with the base station (1e-02). For example, the terminal can transmit an RRC connection resumption request message (RRCResumeRequest) including the identifier to the base station that does not signal the useFullResumeId field.

[0125] -ran-PagingCycle

[0126] ■ A UE-specific paging cycle allocated to a RRC disabled mode terminal (1e-01) and can be configured with a value of a specific radio frame.

[0127] - LAN Notification Area Information (ran-NotificationAreaInfo)

[0128] ■ RRC disabled mode is set to determine the location of the terminal (1e-01), and LAN notification area information can be set through one of the following methods.

[0129] ◆ Method 1: Cell list consisting of one or more cells (cellList)

[0130] ● Each cell can be configured with one Public Land Mobile Network (PLMN) identifier (PLMN-Identity) and one cell identifier (CellIdentity).

[0131] ◆ Method 2: A list consisting of one or more LAN area settings (ran-AreaConfigList)

[0132] ● Each LAN area configuration can be configured with one PLMN identifier and one LAN area (ran-Area). Since a LAN area can be smaller than or equal to a tracking area, a LAN area can be configured with one tracking area code (trackingAreaCode) or with one tracking area code and one or more RAN area codes (RAN-AreaCode). That is, a RAN area code can be used to identify a specific RAN area within the scope of a tracking area.

[0133] - t380

[0134] ■ A timer that periodically triggers a LAN notification area update procedure, which can be set to a specific timer time value. For example, when an RRC disabled mode terminal (1e-01) receives a t380 value from a base station (1e-01), it can drive a T380 timer with the corresponding value, and when the driven T380 timer expires, it can trigger a LAN notification area update procedure.

[0135] - Next hop chaining count (nextHopChainingCount)

[0136] ■ Initial K gNB A counter counting how many NH-derivations have already been performed from this initial K gNB ) to K gNB Used when updating a key, and may be set to one of the numbers 0 to 7 in one embodiment.

[0137] The terminal operation performed when the terminal (1e-01) receives an RRC connection release message containing reservation setting information may be as follows.

[0138] - The terminal may apply the received reservation setting information. At this time, the terminal may not apply the received next hop chaining count.

[0139] - If the reservation setting information includes t380, the terminal can operate the T380 timer by setting the timer value to t380.

[0140] - The terminal can report the suspension of the RRC connection to the upper layers of the terminal.

[0141] - The terminal can transition to RRC deactivation mode (1e-10) and perform cell selection process (1e-15).

[0142] At step 1e-17, the RRC disabled mode terminal (1e-01) can perform a cell reselection process.

[0143] At step 1e-20, the RRC disabled mode terminal (1e-01) may be triggered to perform a RAN Notification Area Update (RNAU) procedure under certain conditions. For example, the terminal may perform the RNAU procedure when the T380 timer it has started expires or when it receives SIB1 from a cell it has reselected or is to reselect and the cell does not belong to the configured RAN Notification Area information. Accordingly, the terminal may initiate an RRC connection resumption procedure to start the T319 timer (1e-31), establish reverse synchronization with the base station (1e-02), and transmit an RRC connection resumption request message (RRCResumeRequest) or an RRC connection resumption request message 1 (RRCResumeRequest1) to the base station (1e-35). When the T319 timer driven in step 1e-31 expires (1e-36), the terminal can transition (1e-40) to the RRC idle mode (RRC_IDLE). For reference, the terminal that transmitted the RRC connection resumption request message or the RRC connection resumption request message 1 to the base station through step 1e-35 can stop the T319 timer driven in step 1e-31 when it receives a predetermined RRC response message (e.g., an RRC connection release message, an RRC connection rejection message (RRCReject), an RRC connection setup message (RRCSetup), an RRC connection resumption message (RRCResume)) from the base station.

[0144] FIG. 1f is a diagram illustrating a next-generation mobile communication system structure that supports network energy saving according to an embodiment of the present invention.

[0145] Referring to FIG. 1f, a next-generation mobile communication system supporting network energy saving may be composed of a next-generation base station (1f-01, g Node B, hereinafter referred to as gNB, Node B or base station), a sync cell (1f-05, Synchronization cell), a data cell (1f-06, 1f-07, 1f-08), and a terminal (1f-09, User Equipment (UE)).

[0146] A gNB (1f-01) may consist of a CU (1f-02, Central Unit) and one or more DUs (1f-03, 1f-04, Distributed Units). A CU may support one or more DUs, and a DU may support only one or more Sync cells, or may support only one or more Data cells, or may support both one or more Sync cells and one or more Data cells simultaneously.

[0147] UE (1f-09) can access an external network via gNB through a data cell.

[0148] FIG. 1g is a diagram illustrating cells that support network energy saving according to an embodiment of the present invention.

[0149] Referring to FIG. 1g, a Sync cell (1g-01, Synchronization cell) may be powered on. The state of a cell that is powered on may be referred to as active, and the Sync cell according to the present disclosure may always be active. The main functions of an active Sync cell may include some of the following functions.

[0150] - Broadcast of Sync cell-SSB (Synchronization signal block)

[0151] - Broadcast of Sync cell-SIB (system information block)

[0152] - Paging message transmission

[0153] - Mobility support of RRC_IDLE and RRC_INACTIVE UE

[0154] As described above, the sync cell can be operated in a low frequency band (e.g., 700 MHz) that is easy to secure wide coverage in order to transmit control signals to the terminal and efficiently support mobility of the terminal in RRC idle mode or RRC deactivation mode.

[0155] The data cell (1g-02, 1g-03, 1g-04) can be separately equipped and operated with a receiver (Wake-Up Receiver, WUR) that can receive a wake-up signal (WUS) transmitted by a terminal (1g-05) and a transceiver (Main transceiver or Main Radio, MR) that can transmit and receive all control signals and data except for the WUS to and from the terminal. Since it is difficult to predict when the terminal will transmit the WUS, the data cell can operate by always turning on the power of the WUR. On the other hand, when the terminal and the data cell do not transmit or receive data for a predetermined period of time, the data cell can turn off or turn on the power of the MR for efficient energy saving. The state of a cell in which the MR of the data cell is turned off can be referred to as inactive, and the state of a cell in which the MR of the data cell is turned on can be referred to as active. The data cell according to the present disclosure may be an active data cell or an inactive data cell depending on certain conditions. For example, a specific data cell (1g-02) may change its state from inactive to active when it receives a WUS (wake-up signal) transmitted by a terminal (1g-05) with a signal strength higher than a certain level. The main functions of the active data cell (1g-02) may include some of the following functions.

[0156] - Receiving a wake-up signal transmitted by the terminal (WUS (wake up signal) reception)

[0157] - Data cell synchronization signal transmission (Broadcast of data cell-SSB (Synchronization signal block))

[0158] - Data cell system information transmission (Broadcast of Datacell-SIB (system information block))

[0159] - Support of Random Access Procedure

[0160] - Support of RRC_CONNECTED UE and its mobility

[0161] The main functions of the Inactive Data cell (1g-03, 1g-04) may include some of the following functions:

[0162] - Receiving a wake-up signal transmitted by the terminal (WUS (wake up signal) reception)

[0163] The main functions of the terminal (1g-05) may include some of the following functions.

[0164] - Sync cell selection or reselection for mobility support in RRC idle mode or RRC disabled mode.

[0165] - Reception of paging message transmitted by sync cell

[0166] - Performance of random access procedure with data cell and establishment of RRC connection with data cell

[0167] - Data transmission and reception in data cell and RRC connection mode

[0168] FIG. 1h is a flowchart illustrating a process in which a terminal performs an RRC connection resume procedure with a data cell in a next-generation mobile communication system supporting network energy saving according to an embodiment of the present invention.

[0169] Referring to FIG. 1h, the terminal (1h-01) may be in RRC connection mode (RRC_CONNECTED) by establishing an RRC connection with Active Data cell 1 (1h-03) (1h-10). At this time, the Data cell 1 (1h-03) may be in an Active state, and the remaining Data cells (1h-04, 1h-05) may be in an Inactive state.

[0170] At step 1h-15, Active Data cell 1 (1h-03) may transmit an RRC connection release message (RRCRelease) containing suspension configuration information (suspendConfig) to transition the terminal (1h-01) from RRC connected mode to RRC inactive mode (RRC_INACTIVE). Specifically, the cell may transmit the message received from a CU within a base station supporting the cell to the terminal (1h-01). The present disclosure proposes that the suspension configuration information includes at least one of the following:

[0171] - Full Terminal Resumption Identifier (FullI-RNTI)

[0172] ■ An identifier used to identify a reserved terminal context of an RRC disabled mode terminal (1h-01), which may be composed of x bits (x is an integer greater than 0).

[0173] ■ The Sync cell (1h-02) can use the identifier when transmitting a paging message to the RRC deactivation mode terminal (1h-01) in the future. For example, the Sync cell (h-02) can transmit a paging message containing a paging record (PagingRecord) set to the paging terminal identifier (PagingUE-Identity) to the terminal (1h-01). In the present disclosure, the Sync cell (1h-02) transmits a paging message to the terminal (1h-01), while the Data cells (1h-03, 1h-04, 1h-05) do not transmit a paging message to the terminal (1h-01). This is because the Sync cell can support wider paging coverage while using less energy than the Data cell.

[0174] ■ The RRC deactivation mode terminal (1h-01) can use the identifier when performing an RRC connection resumption procedure with a specific active Data cell (1h-03 or 1h-04 or 1h-05) in the future. For example, the terminal can transmit an RRC connection resumption request message 1 (RRCResumeRequest1) including the identifier to the active Data cell to which the RRC connection is to be resumed. Whether or not the identifier is used can be determined by signaling that instructs the active Data cell to which the RRC connection is to be resumed to perform an RRC connection resumption procedure through the identifier.

[0175] - Segmented Terminal Resumption Identifier (ShortI-RNTI)

[0176] ■ An identifier used to identify a reserved terminal context of an RRC deactivation mode terminal (1h-01), which may be composed of y bits (0 < y< x, y is an integer). That is, the identifier may be composed of fewer bits than a complete terminal resumption identifier.

[0177] ■ The RRC inactive mode terminal (1h-01) can use the identifier when performing an RRC connection resumption procedure with a specific active Data cell (1h-03 or 1h-04 or 1h-05) in the future. For example, the terminal can transmit an RRC connection resumption request message (RRCResumeRequest) including the identifier to the active Data cell to which the RRC connection is to be resumed. Whether or not the identifier is used can be determined by signaling that instructs the active Data cell to which the RRC connection is to be resumed to perform the RRC connection resumption procedure through the identifier.

[0178] -ran-PagingCycle

[0179] ■ A UE-specific paging cycle assigned to a RRC deactivation mode terminal (1h-01) may be configured as a value of a specific radio frame. The terminal may apply the cycle when determining a time to receive a paging message to a current Sync cell (i.e., a Serving Sync cell) (1h-02), and the Sync cell (1h-02) may apply the cycle when determining a time to transmit a paging message to the terminal (1h-01).

[0180] - Network Energy Saving (NES) LAN Notification Area Information (NES-ran-NotificationAreaInfo)

[0181] ■ It is set to identify the location of the RRC disabled mode terminal (1h-01), and the present disclosure proposes setting network energy saving LAN notification area information through at least one of the following methods.

[0182] ◆ Method 1: Sync cell list consisting of one or more Sync cells

[0183] ● The above Sync cell list may be composed of one or more Sync cell identifiers. At this time, each Sync cell identifier may be set to a combination of at least one of an identifier indicating a mobile communication network to which the RRC disabled mode terminal (1h-01) has subscribed (e.g., PLMN-Identity), an identifier that can unambiguously identify the Sync cell within the corresponding mobile communication network identifier (e.g., SyncCell-Identity), and a tracking area code (TrackingAreaCode) to which the Sync cell belongs. That is, the network energy saving LAN notification area setting information has a characteristic that information on the Data cell is not included, and this is to support the mobility of the RRC disabled mode terminal in units of Sync cells because the Sync cell can efficiently provide wider coverage than the Data cell.

[0184] ◆ Method 2: A Sync cell list consisting of one or more Sync cells and a Data cell list consisting of one or more Data cells that are optionally set for each Sync cell.

[0185] ● The above Sync cell list is composed of one or more Sync cell identifiers, and at this time, the Data cell list may not include a Data cell identifier associated with each Sync cell identifier, or may include one or more Data Cell identifiers.

[0186] ● Each Sync cell identifier may be set to a combination of at least one of an identifier indicating a mobile communication network to which an RRC deactivated mode terminal (1h-01) has subscribed (e.g., PLMN-Identity), an identifier that can unambiguously identify a Sync cell within the corresponding mobile communication network identifier (e.g., SyncCell-Identity), and a tracking area code (TrackingAreaCode) to which the Sync cell belongs.

[0187] ● Each data cell identifier may be set to a combination of at least one of an identifier indicating a mobile communication network to which an RRC deactivated mode terminal (1h-01) has subscribed (e.g., PLMN-Identity), an identifier that can unambiguously identify a data cell within the corresponding mobile communication network identifier (e.g., DataCell-Identity), a SyncCell-Identity, and a predetermined identifier that can identify a data cell within a Sync cell.

[0188] ● If there is no data cell identifier associated with the sync cell identifier, the RRC disabled mode terminal (1h-01) can determine that all data cells associated with the sync cell belong to the network energy saving LAN notification area information. If there is one or more data cell identifiers associated with the sync cell identifier, the terminal can determine that only one or more data cells set with the data cell identifier among all data cells associated with the sync cell belong to the network energy saving LAN notification area information.

[0189] ◆ Method 3: A Sync cell list consisting of one or more Sync cells and a Data area code list consisting of one or more Data area codes that are optionally set for each Sync cell.

[0190] ● The Sync cell list consists of one or more Sync cell identifiers, and the Data area code list may not include a Data area code associated with each Sync cell identifier, or may include one or more Data area codes.

[0191] ● Each Sync cell identifier may be set to a combination of at least one of an identifier indicating a mobile communication network to which an RRC deactivated mode terminal (1h-01) has subscribed (e.g., PLMN-Identity), an identifier that can unambiguously identify a Sync cell within the corresponding mobile communication network identifier (e.g., SyncCell-Identity), and a tracking area code (TrackingAreaCode) to which the Sync cell belongs.

[0192] ● The data area code is a code used to identify one or more data cells operated in association with a sync cell, and can be composed of z bits (z is an integer greater than 0). When there are multiple data cells operated in association with a sync cell, the number of bits required for signaling can be reduced by setting a data area code that can express them all at once rather than setting data cell identifiers one by one. In particular, a greater signaling effect can be obtained when only one data area code is used for one sync cell. Of course, the data area code can also be used to identify one or more data cells that are not operated in association with a sync cell.

[0193] ● If there is no data area code associated with the sync cell identifier, the RRC disabled mode terminal (1h-01) can determine that all data cells associated with the sync cell belong to the network energy saving LAN notification area information. If there is one or more sync cells and data area codes associated with them, the terminal can determine that only data cells that belong to one or more of the data area codes set among all data cells associated with the sync cell belong to the network energy saving LAN notification area information.

[0194] ◆ Method 4: A list consisting of one or more network energy-saving LAN zone settings.

[0195] ● The above list may be composed of one or more network energy saving LAN area settings. At this time, each network energy saving LAN area setting may be set with an identifier (e.g., PLMN-Identity) indicating a mobile communication network to which the RRC disabled mode terminal (1h-01) has subscribed and a network energy saving LAN area. The network energy saving LAN area may be set with one tracking area code, one tracking area code and one or more LAN area codes, or may be additionally set with one tracking area code and one or more LAN area codes and one or more Data area codes for each LAN area code. At this time, the tracking area code is a code used when identifying one or more Sync cells, the LAN area code is a code used to identify / distinguish one or more Sync cells in a specific LAN area within the tracking area, and the Data area code may mean a code used to identify / distinguish one or more Data cells in a specific Data area within the LAN area.

[0196] - t380

[0197] ■ A timer that periodically triggers a LAN notification area update procedure, which can be set to a specific timer time value. For example, when an RRC disabled mode terminal (1h-01) receives a t380 value, it can drive the T380 timer with the corresponding value, and when the driven T380 timer expires, it can be triggered accordingly to perform a LAN notification area update procedure.

[0198] - Next hop chaining count (nextHopChainingCount)

[0199] ■ Initial K gNBA counter counting how many NH-derivations have already been performed from this initial K gNB ) to K gNB Used when updating a key, and can be set to one of the numbers from 0 to 7.

[0200] - t3xx

[0201] ■ A timer that is started when the RRC connection resumption procedure is triggered, and can be set to a specific timer time value. For example, the RRC inactive mode terminal (1h-01) can start the T3xx timer with a specific time value (e.g., t3xx) when the RRC connection resumption procedure is triggered, and can (re)select or find an active data cell that can be connected while the T3xx timer is running. When the terminal (1h-01) (re)selects or finds an active data cell, the terminal (1h-01) can stop the running T3xx timer. When the running T3xx timer expires, the terminal (1h-01) can transition to the RRC idle mode or perform a sync cell selection or reselection procedure in the RRC inactive mode.

[0202] In the above, the active Data cell 1 (1h-03) may be changed to an inactive state under certain conditions. For example, the active Data cell may be changed to an inactive state if it does not receive a wake-up signal (hereinafter referred to as WUS) from the terminal (1h-01) for a certain period of time.

[0203] The terminal operation performed when the terminal (1h-01) receives an RRC connection release message containing reservation setting information may be as follows.

[0204] - The terminal may apply the received reservation setting information. At this time, the terminal may not apply the received next hop chaining count.

[0205] - If the reservation setting information includes t380, the terminal can operate the T380 timer by setting the timer value to t380.

[0206] - The terminal can report the suspension of the RRC connection to the upper layers of the terminal.

[0207] - The terminal can transition to RRC deactivation mode (1h-20) and receive (1h-25) a synchronization signal (Sync cell-Synchorinization Signal Block, hereinafter referred to as Sync cell-SSB) transmitted by the Sync cell (1h-02) to select or camp on (1h-30) the Sync cell (1h-02). For example, the terminal can camp on the Sync cell if the Sync cell selection reception signal derived from the received Sync cell-SSB and the signal quality are greater than a predetermined threshold value.

[0208] At step 1h-31, the terminal (1h-01) can receive sync cell system information (Sync cell-System Information Block, hereinafter referred to as Sync cell-SIB) from the sync cell (1h-02). Then, the terminal can perform a sync cell reselection procedure (1h-32).

[0209] The above Sync cell-SSB (1h-25) and Sync cell-SIB (1h-31) may be periodically transmitted by the Sync cell (1h-02). At least one of the Sync cell-SSB and Sync cell-SIB in the present disclosure may include at least one of the following information.

[0210] - Time / frequency resource information for the terminal (1h-01) to transmit a wake-up signal (WUS) (time / frequency resource for WUS)

[0211] - Configuration information required to select or reselect a sync cell

[0212] ■ One or more sync cell identifiers

[0213] ■ One or more frequencies on which sync cells operate

[0214] ■ Cell reselection priority by sync cell frequency

[0215] ■ Parameters or thresholds required to select or reselect a sync cell

[0216] - Information about each Sync cell and the Data cell associated with each Sync cell (e.g., Data cell identifier, Data area code)

[0217] - Paging settings information

[0218] - t3xx

[0219] At step 1h-35, the RRC disabled mode terminal (1h-01) may trigger a RAN Notification Area Update (RNAU) procedure according to a predetermined condition. For example, the terminal may perform the RNAU procedure when the T380 timer it has run expires, or when the terminal receives a Sync cell-SSB or Sync-cell SIB from a Sync cell it has reselected or is to be reselected and the corresponding cell does not belong to the configured Network Energy Saving (NES) RAN notification area information, or when the active Data cell to be accessed (or to which the RRC connection resumption procedure is to be initiated) does not belong to the configured Network Energy Saving (NES) RAN notification area information. The terminal according to the present disclosure may start a T3xx timer (1h-36) when an RRC connection resume procedure is triggered, and transmit a wake-up signal (hereinafter referred to as WUS) (1h-40) to wake up an inactive data cell as part of performing an RRC connection resume procedure. According to one embodiment, the terminal may first transmit a WUS and then start the T3xx timer.

[0220] In the above-described step, the terminal (1h-01) may drive the T3xx timer with the t3xx value set in step 1h-15 if the value is set thereto, and if not (i.e., if the t3xx value is not set in step 1h-15), the terminal may drive the T3xx timer with the t3xx value received in step 1h-25 or 1h-31. Of course, the terminal may also drive the T3xx timer with a pre-determined or default t3xx value if it is not provided with a separate t3xx value. While the T3xx timer is running, the terminal may select or find an active Data cell to which it wishes to connect. If the terminal does not select or find an active Data cell to which it wishes to connect by the time the T3xx timer expires, the terminal may transition to RRC idle mode (RRC_IDLE) or perform a sync cell selection or reselection process. For reference, an RRC disabled mode terminal can transition to RRC idle mode when (re)selecting a sync cell or perform the process of selecting or searching for an active data cell again while in RRC disabled mode.

[0221] In the above-described step, the wake-up signal transmitted by the terminal (1h-01) may be a dedicated signal for waking up only a specific inactive Data cell, or alternatively, may be a common signal for waking up all inactive Data cells (or all inactive Data cells associated with a Sync cell). For reference, in order to save network energy, among the inactive Data cells (1h-03, 1h-04, 1h-05) that have received the WUS, an inactive Data cell (1h-03) that satisfies a certain condition may be powered on and become an active Data cell. For example, when the WUS reception signal strength is greater than a certain threshold value, or through negotiation between the Data cells that have received the WUS, only the Data Cell that has the strongest signal strength for receiving the WUS may be powered on and become an active Data cell. For reference, if the Terminal has already selected or found an active Data cell to connect to before transmitting the WUS, the WUS may not be transmitted.

[0222] In step 1h-45, active Data cell 1 (1h-03) can transmit a Data cell synchronization signal (Data cell-SSB) and Data cell system information (Data cell-SIB). The synchronization signal and system information can include at least one of an identifier identifying the Data cell, a Data area code, information indicating which Sync cell it is associated with, and information for accessing the Data cell.

[0223] At step 1h-50, the RRC disabled mode terminal (1h-01) can find or select an active data cell to connect to based on the information received at step 1h-45, and stop the running T3xx timer.

[0224] An RRC-deactivated mode terminal (1h-01) can initiate an RRC connection resumption procedure to start a T319 timer (1h-51), establish reverse synchronization with a found or selected active Data cell 1 (1h-03), and transmit an RRC connection resumption request message (RRCResumeRequest) or an RRC connection resumption request message 1 (RRCResumeRequest1) to the active Data cell 1 (1h-55). In response, the active Data cell 1 can transmit an RRC connection release message containing reservation configuration information to the terminal (1h-60). After receiving the RRC connection release message, the terminal can operate in an RRC-deactivated mode state (1h-65). Later, a Sync cell (1h-02) can transmit a paging message to the RRC-deactivated mode terminal (1h-70) for a predetermined reason (e.g., to provide a Mobile Terminated service). If the paging is RAN-initiated, the paging message may include a Full I-RNTI (FullI-RNTI) that identifies the terminal. Of course, if the paging is Core Network-initiated, the paging message may include an identifier that identifies the terminal in the Core Network.

[0225] An RRC inactive mode terminal according to the present disclosure has a feature that, when an RRC connection resumption procedure is triggered, it first starts a T3xx timer and sends a WUS signal. When an active data cell to be connected is selected or found to initiate an RRC connection resumption procedure, the terminal can stop the running T3xx timer and initiate an RRC connection resumption procedure as in the embodiment described above with reference to FIG. 1e. When the T3xx timer expires, the terminal can transition to an RRC idle mode or perform a procedure to reselect a sync cell that is not an active data cell.

[0226] A Sync cell according to the present disclosure may transmit a paging message to a terminal but may not perform a direct RRC connection resumption procedure with the terminal, and a Data cell may perform a direct RRC connection resumption procedure but may not transmit a paging message to the terminal.

[0227] FIG. 1i is a flowchart illustrating a process in which a terminal performs an RRC connection resume procedure with a data cell in a next-generation mobile communication system supporting network energy saving according to an embodiment of the present invention.

[0228] Referring to FIG. 1i, the terminal (1i-01) can operate in RRC connected mode (RRC_CONNECTED) by establishing an RRC connection with Active Data cell 1 (1i-03) (1i-10). At this time, the Data cell 1 may be in an Active state, and the remaining Data cells (1i-04, 1i-05) may be in an Inactive state.

[0229] At step 1i-15, Active Data cell 1 (1i-03) may transmit an RRC disconnection message (RRCRelease) containing suspension configuration information (suspendConfig) to transition the terminal (1i-01) from RRC connected mode to RRC inactive mode (RRC_INACTIVE). Specifically, the cell may transmit a disconnection message received from a CU within a base station supporting the cell to the terminal. The present disclosure proposes that the suspension configuration information includes at least one of the following:

[0230] - Full Terminal Resumption Identifier (FullI-RNTI)

[0231] ■ An identifier used to identify a reserved terminal context of an RRC disabled mode terminal (1i-01), which can be composed of x bits (x is an integer greater than 0).

[0232] ■ The Sync cell (1i-02) may use the identifier when transmitting a paging message to the RRC deactivation mode terminal (1i-01) in the future. For example, the Sync cell may transmit a paging message containing a paging record (PagingRecord) in which a paging terminal identifier (PagingUE-Identity) is set to the identifier to the terminal. In the present disclosure, the Sync cell may transmit a paging message to the terminal, and the Data cell may not transmit a paging message to the terminal. That is, the Sync cell may transmit a paging message received from a CU in a base station supporting the Sync cell to the terminal. This is because the Sync cell can support a wider paging coverage while using less energy than the Data cell.

[0233] ■ The RRC deactivation mode terminal (1i-01) can use the identifier when performing an RRC connection resumption procedure with a specific active Data cell (1i-03 or 1i-04 or 1i-05) in the future. For example, the terminal can transmit an RRC connection resumption request message 1 (RRCResumeRequest1) including the identifier to the active Data cell to which the RRC connection is to be resumed. Whether or not the identifier is used can be determined by signaling that instructs the active Data cell to which the RRC connection is to be resumed to perform an RRC connection resumption procedure through the identifier.

[0234] - Segmented Terminal Resumption Identifier (ShortI-RNTI)

[0235] ■ An identifier used to identify a reserved terminal context of an RRC deactivation mode terminal (1i-01), which may be composed of y bits (0 < y< x, y is an integer). That is, the identifier may be composed of fewer bits than a complete terminal resumption identifier.

[0236] ■ The RRC inactive mode terminal (1i-01) can use the identifier when performing an RRC connection resumption procedure with a specific active Data cell (1i-03 or 1i-04 or 1i-05) in the future. For example, the terminal can transmit an RRC connection resumption request message (RRCResumeRequest) including the identifier to the active Data cell to which the RRC connection is to be resumed. Whether or not the identifier is used can be determined by signaling that instructs the active Data cell to which the RRC connection is to be resumed to perform the RRC connection resumption procedure through the identifier.

[0237] -ran-PagingCycle

[0238] ■ A UE-specific paging cycle assigned to a RRC deactivation mode terminal (1i-01) may be configured as a value of a specific radio frame. The terminal may apply the cycle when determining when to receive a paging message to the current Sync cell (i.e., the Serving Sync cell), and the Sync cell may apply the cycle when determining when to transmit a paging message to the terminal.

[0239] - Network Energy Saving (NES) LAN Notification Area Information (NES-ran-NotificationAreaInfo)

[0240] ■ It is set to determine the location of the RRC disabled mode terminal (1i-01), and the present disclosure proposes setting network energy saving LAN notification area information through at least one of the following methods.

[0241] ◆ Method 1: Sync cell list consisting of one or more Sync cells

[0242] ● The above Sync cell list may be composed of one or more Sync cell identifiers. At this time, each Sync cell identifier may be set to a combination of at least one of an identifier indicating a mobile communication network to which the RRC disabled mode terminal (1i-01) has subscribed (e.g., PLMN-Identity), an identifier that can unambiguously identify the Sync cell within the corresponding mobile communication network identifier (e.g., SyncCell-Identity), and a tracking area code (TrackingAreaCode) to which the Sync cell belongs. That is, the network energy saving LAN notification area setting information has a characteristic that information on the Data cell is not included, and this is to support the mobility of the RRC disabled mode terminal in units of Sync cells because the Sync cell can efficiently provide wider coverage than the Data cell.

[0243] ◆ Method 2: A Sync cell list consisting of one or more Sync cells and a Data cell list consisting of one or more Data cells that are optionally set for each Sync cell.

[0244] ● The above Sync cell list is composed of one or more Sync cell identifiers, and at this time, the Data cell list may not include a Data cell identifier associated with each Sync cell identifier or may include one or more Data Cell identifiers.

[0245] ● Each Sync cell identifier may be set to a combination of at least one of an identifier indicating a mobile communication network to which an RRC disabled mode terminal (1i-01) has subscribed (e.g., PLMN-Identity), an identifier that can unambiguously identify a Sync cell within the corresponding mobile communication network identifier (e.g., SyncCell-Identity), and a tracking area code (TrackingAreaCode) to which the Sync cell belongs.

[0246] ● Each data cell identifier may be set to a combination of at least one of an identifier indicating a mobile communication network to which an RRC disabled mode terminal (1i-01) has subscribed (e.g., PLMN-Identity), an identifier that can unambiguously identify a data cell within the corresponding mobile communication network identifier (e.g., DataCell-Identity), a SyncCell-Identity, and a predetermined identifier that can identify a data cell within a Sync cell.

[0247] ● If there is no data cell identifier associated with the sync cell identifier, the RRC disabled mode terminal (1i-01) can determine that all data cells associated with the sync cell belong to the network energy saving LAN notification area information. If there is one or more data cell identifiers associated with the sync cell identifier, the terminal can determine that only one or more data cells set with the data cell identifier among all data cells associated with the sync cell belong to the network energy saving LAN notification area information.

[0248] ◆ Method 3: A Sync cell list consisting of one or more Sync cells and a Data area code list consisting of one or more Data area codes that are optionally set for each Sync cell.

[0249] ● The Sync cell list consists of one or more Sync cell identifiers, and the Data area code list may not include a Data area code associated with each Sync cell identifier, or may include one or more Data area codes.

[0250] ● Each Sync cell identifier may be set to a combination of at least one of an identifier indicating a mobile communication network to which an RRC disabled mode terminal (1i-01) has subscribed (e.g., PLMN-Identity), an identifier that can unambiguously identify a Sync cell within the corresponding mobile communication network identifier (e.g., SyncCell-Identity), and a tracking area code (TrackingAreaCode) to which the Sync cell belongs.

[0251] ● The data area code is a code used to identify one or more data cells operated in association with a sync cell, and can be composed of z bits (z is an integer greater than 0). When there are multiple data cells operated in association with a sync cell, the number of bits required for signaling can be reduced by setting a data area code that can express them all at once rather than setting data cell identifiers one by one. In particular, a greater signaling effect can be obtained when only one data area code is used for one sync cell. Of course, the data area code can also be used to identify one or more data cells that are not operated in association with a sync cell.

[0252] ● If there is no data area code associated with the sync cell identifier, the RRC disabled mode terminal (1i-01) can determine that all data cells associated with the sync cell belong to the network energy saving LAN notification area information. If there is one or more sync cells and data area codes associated with them, the terminal can determine that only data cells that belong to one or more of the data area codes set among all data cells associated with the sync cell belong to the network energy saving LAN notification area information.

[0253] ◆ Method 4: A list consisting of one or more network energy-saving LAN zone settings.

[0254] ● The above list may be composed of one or more network energy saving LAN area settings. At this time, each network energy saving LAN area setting may be set with an identifier (e.g., PLMN-Identity) indicating a mobile communication network to which the RRC disabled mode terminal (1i-01) has subscribed and a network energy saving LAN area. The network energy saving LAN area may be set with one tracking area code, one tracking area code and one or more LAN area codes, or may be additionally set with one tracking area code and one or more LAN area codes and one or more Data area codes for each LAN area code. At this time, the tracking area code is a code used when identifying one or more Sync cells, the LAN area code is a code used to identify / distinguish one or more Sync cells in a specific LAN area within the tracking area, and the Data area code may mean a code used to identify / distinguish one or more Data cells in a specific Data area within the LAN area.

[0255] - t380

[0256] ■ A timer that periodically triggers a LAN notification area update procedure, which can be set to a specific timer time value. For example, when an RRC disabled mode terminal (1i-01) receives a t380 value, it can drive the T380 timer with the corresponding value, and when the driven T380 timer expires, it can be triggered accordingly to perform a LAN notification area update procedure.

[0257] - Next hop chaining count (nextHopChainingCount)

[0258] ■ Initial K gNBA counter counting how many NH-derivations have already been performed from this initial K gNB ) to K gNB Used when updating a key, and can be set to one of the numbers from 0 to 7.

[0259] In the above, the active Data cell 1 (1i-03) may be changed to an inactive state under certain conditions. For example, the active Data cell may be changed to an inactive state if it does not receive a wake-up signal (hereinafter referred to as WUS) from the terminal (1i-01) for a certain period of time.

[0260] The terminal action performed when the terminal (1i-01) receives an RRC connection release message containing reservation setting information may be as follows.

[0261] - The terminal may apply the received reservation setting information. At this time, the terminal may not apply the received next hop chaining count.

[0262] - If the reservation setting information includes t380, the terminal can operate the T380 timer by setting the timer value to t380.

[0263] - The terminal can report the suspension of the RRC connection to the upper layers of the terminal.

[0264] - The terminal can transition to RRC deactivation mode (1i-20) and receive (1i-25) a synchronization signal (Sync cell-Synchorinization Signal Block, hereinafter referred to as Sync cell-SSB) transmitted by a Sync cell (1i-02) to select the Sync cell or camp on the Sync cell (1i-30). For example, the terminal can camp on the Sync cell if the Sync cell selection reception signal derived from the received Sync cell-SSB and the signal quality are greater than a predetermined threshold value.

[0265] In step 1i-31, the terminal (1i-01) can receive sync cell system information (Sync cell-System Information Block, hereinafter referred to as Sync cell-SIB) transmitted by the sync cell (1i-02). Then, the terminal can perform a sync cell reselection procedure (1i-32).

[0266] The above Sync cell-SSB (1i-25) and Sync cell-SIB (1i-31) may be periodically transmitted by the Sync cell (1i-02). At least one of the Sync cell-SSB and Sync cell-SIB in the present disclosure may include at least one of the following information.

[0267] - Time / frequency resource information for the terminal (1i-01) to transmit a wake-up signal (WUS) (time / frequency resource for WUS)

[0268] - Configuration information required to select or reselect a sync cell

[0269] ■ One or more sync cell identifiers

[0270] ■ One or more frequencies on which sync cells operate

[0271] ■ Cell reselection priority by sync cell frequency

[0272] ■ Parameters or thresholds required to select or reselect a sync cell

[0273] - Information about each Sync cell and the Data cell associated with each Sync cell (e.g., Data cell identifier, Data area code)

[0274] - Paging settings information

[0275] In step 1i-35, the RRC disabled mode terminal (1i-01) may trigger a RAN Notification Area Update (RNAU) procedure according to a predetermined condition. For example, the terminal may perform the RNAU procedure when the T380 timer it has run expires, or when the terminal receives a Sync cell-SSB or Sync-cell SIB from a Sync cell it has reselected or is to be reselected and the corresponding cell does not belong to the configured Network Energy Saving (NES) RAN notification area information, or when the active Data cell to be accessed (or to which the RRC connection resumption procedure is to be initiated) does not belong to the configured Network Energy Saving (NES) RAN notification area information. The terminal according to the present disclosure may start a T319 timer (1i-36) when an RRC connection resume procedure is triggered, and transmit a wake-up signal (hereinafter referred to as WUS) (1i-40) to wake up an inactive data cell as part of performing an RRC connection resume procedure. According to one embodiment, the terminal may first transmit a WUS and then start the T319 timer.

[0276] In the above-described step, the terminal (1i-01) can select or find an active Data cell to which it wishes to connect while the T319 timer is running. If the terminal fails to select or find an active Data cell to which it wishes to connect until the T319 timer expires, the terminal can transition to an RRC idle mode (RRC_IDLE). For reference, an RRC deactivated mode terminal can also select or reselect a Sync cell while the T319 timer is running. The terminal can transition to the RRC idle mode when (re)selecting a Sync cell (the T319 timer stops during the transition), and can perform the process of selecting or finding an active Data cell again in the RRC deactivated mode while the T319 timer is running.

[0277] In the above-described step, the wake-up signal transmitted by the terminal (1i-01) may be a dedicated signal for waking up only a specific inactive Data cell, or alternatively, may be a common signal for waking up all inactive Data cells (or all inactive Data cells associated with a Sync cell). For reference, in order to save network energy, among the inactive Data cells (1i-03, 1i-04, 1i-05) that have received the WUS, an inactive Data cell (1i-03) that satisfies a certain condition may be powered on and become an active Data cell. For example, when the WUS reception signal strength is greater than a certain threshold value, or through negotiation between the Data cells that have received the WUS, only the Data Cell that has the strongest signal strength for receiving the WUS may be powered on and become an active Data cell. For reference, if the Terminal has already selected or found an active Data cell to connect to before transmitting the WUS, the WUS may not be transmitted.

[0278] In step 1i-45, active Data cell 1 (1i-03) can transmit a Data cell synchronization signal (Data cell-SSB) and Data cell system information (Data cell-SIB). The synchronization signal and system information can include at least one of an identifier for identifying the Data cell, a Data area code, information indicating which Sync cell it is associated with, and information for accessing the Data cell. In addition, the RRC inactive mode terminal (1i-01) may not stop the T319 timer that has been started even if it finds or selects an active Data cell to which it wants to access based on the received information.

[0279] An RRC-deactivated mode terminal (1i-01) may initiate an RRC connection resumption procedure to establish reverse synchronization with a found or selected active Data cell 1 (1i-03), and transmit (1i-55) an RRC connection resumption request message (RRCResumeRequest) or an RRC connection resumption request message 1 (RRCResumeRequest1) to the active Data cell 1. In response, the active Data cell 1 may transmit (1i-60) an RRC connection release message containing reservation configuration information to the terminal. The terminal may stop a running T319 timer (1i-61) and operate in an RRC-deactivated mode state (1i-65). Later, for a predetermined reason (e.g., to provide a Mobile Terminated service), a Sync cell (1i-02) may transmit (1i-70) a paging message to the RRC-deactivated mode terminal. If the paging is RAN-initiated, the paging message may include a Full I-RNTI (FullI-RNTI) that identifies the terminal. Of course, if the paging is Core Network-initiated, the paging message may include an identifier that identifies the terminal in the Core Network.

[0280] A terminal in RRC inactive mode according to the present disclosure is characterized by first starting a T319 timer and then sending a WUS signal when an RRC connection resumption procedure is triggered. The terminal can stop the T319 timer if it receives a predetermined RRC response message from an active data cell while the timer is running. When the T319 timer expires, the terminal can transition to RRC idle mode.

[0281] A Sync cell according to the present disclosure may transmit a paging message to a terminal but may not perform a direct RRC connection resumption procedure with the terminal, and a Data cell may perform a direct RRC connection resumption procedure but may not transmit a paging message to the terminal.

[0282] FIG. 1j is a block diagram illustrating the internal structure of a terminal according to an embodiment of the present invention.

[0283] Referring to the above drawing, the terminal includes an RF (Radio Frequency) processing unit (1j-10), a baseband processing unit (1j-20), a storage unit (1j-30), and a control unit (1j-40).

[0284] The RF processing unit (1j-10) performs functions for transmitting and receiving signals through a wireless channel, such as signal band conversion and amplification. That is, the RF processing unit (1j-10) up-converts the baseband signal provided from the baseband processing unit (1j-20) into an RF band signal and transmits it through an antenna, and down-converts the RF band signal received through the antenna into a baseband signal. For example, the RF processing unit (1j-10) may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a digital to analog convertor (DAC), an analog to digital convertor (ADC), etc. In the drawing, only one antenna is illustrated, but the terminal may be equipped with multiple antennas. In addition, the RF processing unit (1j-10) may include multiple RF chains. Furthermore, the RF processing unit (1j-10) may perform beamforming. For the above beamforming, the RF processing unit (1j-10) can adjust the phase and size of each signal transmitted and received through multiple antennas or antenna elements. In addition, the RF processing unit can perform MIMO and receive multiple layers when performing the MIMO operation.

[0285] The baseband processing unit (1j-20) performs a conversion function between a baseband signal and a bit stream according to the physical layer specifications of the system. For example, when transmitting data, the baseband processing unit (1j-20) generates complex symbols by encoding and modulating a transmission bit stream. In addition, when receiving data, the baseband processing unit (1j-20) restores the reception bit stream by demodulating and decoding the baseband signal provided from the RF processing unit (1j-10). For example, in the case of following the OFDM (orthogonal frequency division multiplexing) method, when transmitting data, the baseband processing unit (1j-20) generates complex symbols by encoding and modulating a transmission bit stream, maps the complex symbols to subcarriers, and then configures OFDM symbols by performing an inverse fast Fourier transform (IFFT) operation and inserting a cyclic prefix (CP). In addition, when receiving data, the baseband processing unit (1j-20) divides the baseband signal provided from the RF processing unit (1j-10) into OFDM symbol units, restores signals mapped to subcarriers through FFT (fast Fourier transform), and then restores the received bit string through demodulation and decoding.

[0286] The baseband processing unit (1j-20) and the RF processing unit (1j-10) transmit and receive signals as described above. Accordingly, the baseband processing unit (1j-20) and the RF processing unit (1j-10) may be referred to as a transmitter, a receiver, a transceiver, or a communication unit. Furthermore, at least one of the baseband processing unit (1j-20) and the RF processing unit (1j-10) may include a plurality of communication modules to support a plurality of different wireless access technologies. In addition, at least one of the baseband processing unit (1j-20) and the RF processing unit (1j-10) may include different communication modules to process signals of different frequency bands. For example, the different wireless access technologies may include a wireless LAN (e.g., IEEE 802.11), a cellular network (e.g., LTE), etc. Additionally, the different frequency bands may include a super high frequency (SHF) (e.g., 2.NRHz, NRhz) band and a millimeter wave (mm wave) (e.g., 60GHz) band.

[0287] The storage unit (1j-30) stores data such as basic programs, application programs, and setting information for the operation of the terminal. In particular, the storage unit (1j-30) can store information related to a second access node that performs wireless communication using a second wireless access technology. In addition, the storage unit (1j-30) provides the stored data upon request from the control unit (1j-40).

[0288] The above control unit (1j-40) controls the overall operations of the terminal. For example, the control unit (1j-40) transmits and receives signals through the baseband processing unit (1j-20) and the RF processing unit (1j-10). In addition, the control unit (1j-40) records and reads data in the storage unit (1j-40). For this purpose, the control unit (1j-40) may include at least one processor. For example, the control unit (1j-40) may include a communication processor (CP) that performs control for communication and an application processor (AP) that controls upper layers such as application programs.

[0289] FIG. 1k is a block diagram showing the configuration of an NR base station according to an embodiment of the present invention.

[0290] As shown in the above drawing, the base station is configured to include an RF processing unit (1k-10), a baseband processing unit (1k-20), a backhaul communication unit (1k-30), a storage unit (1k-40), and a control unit (1k-50).

[0291] The RF processing unit (1k-10) performs functions for transmitting and receiving signals through a wireless channel, such as signal band conversion and amplification. That is, the RF processing unit (1k-10) up-converts the baseband signal provided from the baseband processing unit (1k-20) into an RF band signal and transmits it through an antenna, and down-converts the RF band signal received through the antenna into a baseband signal. For example, the RF processing unit (1k-10) may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, etc. In the drawing, only one antenna is shown, but the first access node may have multiple antennas. In addition, the RF processing unit (1k-10) may include multiple RF chains. Furthermore, the RF processing unit (1k-10) may perform beamforming. For the above beamforming, the RF processing unit (1k-10) can adjust the phase and magnitude of each signal transmitted and received through multiple antennas or antenna elements. The RF processing unit can perform a downlink MIMO operation by transmitting one or more layers.

[0292] The baseband processing unit (1k-20) performs a conversion function between a baseband signal and a bit stream according to the physical layer specifications of the first wireless access technology. For example, when transmitting data, the baseband processing unit (1k-20) generates complex symbols by encoding and modulating a transmission bit stream. In addition, when receiving data, the baseband processing unit (1k-20) restores the reception bit stream by demodulating and decoding the baseband signal provided from the RF processing unit (1k-10). For example, in the case of OFDM, when transmitting data, the baseband processing unit (1k-20) generates complex symbols by encoding and modulating a transmission bit stream, maps the complex symbols to subcarriers, and then configures OFDM symbols through IFFT operation and CP insertion. In addition, when receiving data, the baseband processing unit (1k-20) divides the baseband signal provided from the RF processing unit (1k-10) into OFDM symbol units, restores the signals mapped to subcarriers through FFT operation, and then restores the received bit string through demodulation and decoding. The baseband processing unit (1k-20) and the RF processing unit (1k-10) transmit and receive signals as described above. Accordingly, the baseband processing unit (1k-20) and the RF processing unit (1k-10) may be referred to as a transmitter, a receiver, a transceiver, a communication unit, or a wireless communication unit.

[0293] The above backhaul communication unit (1k-30) provides an interface for communicating with other nodes within the network. That is, the backhaul communication unit (1k-30) converts a bit string transmitted from the main base station to another node, such as an auxiliary base station or core network, into a physical signal, and converts a physical signal received from the other node into a bit string.

[0294] The storage unit (1k-40) stores data such as basic programs, application programs, and configuration information for the operation of the main base station. In particular, the storage unit (1k-40) can store information on bearers assigned to connected terminals, measurement results reported from connected terminals, and the like. In addition, the storage unit (1k-40) can store information that serves as a judgment criterion for whether to provide or terminate multiple connections to a terminal. In addition, the storage unit (1k-40) provides the stored data at the request of the control unit (1k-50).

[0295] The control unit (1k-50) controls the overall operations of the base station. For example, the control unit (1k-50) transmits and receives signals through the baseband processing unit (1k-20) and the RF processing unit (1k-10) or through the backhaul communication unit (1k-30). In addition, the control unit (1k-50) records and reads data in the storage unit (1k-40). For this purpose, the control unit (1k-50) may include at least one processor.

[0296] The embodiments of the present invention disclosed in this specification and drawings are merely specific examples intended to facilitate easy explanation of the technical content of the present invention and aid understanding thereof, and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical concepts of the present invention are possible in addition to the embodiments disclosed herein.

Claims

1. In a method of operating a base station supporting a sync cell and a data cell in a wireless communication system, A step of transmitting, to a terminal, an RRC (radio resource control) disconnection message including a synchronization cell list for at least one synchronization cell; A step of transmitting a synchronization cell SSB (synchronization signal block) or a synchronization cell SIB (system information block) to the terminal through a synchronization cell; and A method comprising the step of activating one of the data cells that has received a wake-up signal from the terminal and transmitting a data cell SSB or a data cell SIB to the terminal through the activated data cell.

2. In paragraph 1, The above synchronization cell is a cell that always operates in an active state and supports paging functions for terminals. A method wherein the above data cell is a cell that is activated upon receipt of a wake-up signal from the terminal and does not support a paging function for the terminal.

3. In paragraph 1, A method wherein the RRC connection release message additionally includes data cell lists associated with each synchronization cell included in the synchronization cell list.

4. In paragraph 1, The above RRC connection release message includes a list of data area codes set for each synchronization cell included in the synchronization cell list, A method wherein the above data area code is associated with at least one data cell.

5. In a method of a terminal operating in a wireless communication system, A step of receiving an RRC connection release message including a synchronization cell list for at least one synchronization cell from a data cell on which an RRC (radio resource control) connection has been performed; Step of transitioning to RRC inactive mode; A step of receiving a synchronization cell SSB (synchronization signal block) or a synchronization cell SIB (system information block) from a synchronization cell; A step of performing a selection procedure or a reselection procedure for a synchronization cell based on the synchronization cell SSB or the synchronization cell SIB; A step of transmitting a wake-up signal to at least one data cell associated with the synchronization cell; and A method comprising the step of receiving a data cell SSB or a data cell SIB from at least one of the data cells that have received the wake-up signal.

6. In paragraph 5, The above synchronization cell is a cell that always operates in an active state and supports paging functions for terminals. A method wherein the above data cell is a cell that is activated upon receipt of a wake-up signal from the terminal and does not support a paging function for the terminal.

7. In paragraph 5, The above RRC connection release message includes lists of data cells associated with each synchronization cell included in the synchronization cell list or lists of data area codes set for each synchronization cell. A method wherein the above data area code is associated with at least one data cell.

8. In paragraph 5, After transitioning to the RRC inactive mode, a step of driving a timer for searching for a data cell; and A method further comprising the step of stopping the timer and initiating an RRC connection resumption procedure to the selected data cell if a data cell is selected before the timer expires.

9. In a base station supporting sync cells and data cells in a wireless communication system, Transmitter and receiver; and Includes a control unit, The above control unit, To the terminal, transmit an RRC (radio resource control) disconnection message including a synchronization cell list for at least one synchronization cell, The synchronization cell SSB (synchronization signal block) or the synchronization cell SIB (system information block) is transmitted to the terminal through the synchronization cell. A base station configured to activate one of the data cells that receives a wake-up signal from the terminal and transmit a data cell SSB or a data cell SIB to the terminal through the activated data cell.

10. In paragraph 9, The above synchronization cell is a cell that always operates in an active state and supports paging functions for terminals. A base station, wherein the above data cell is a cell that is activated upon receipt of a wake-up signal from the terminal and does not support a paging function for the terminal.

11. In paragraph 9, The above RRC connection release message includes lists of data cells associated with each synchronization cell included in the synchronization cell list or lists of data area codes set for each synchronization cell. A base station, wherein the above data area code is associated with at least one data cell.

12. In a terminal in a wireless communication system, Transmitter and receiver; and Includes a control unit, The above control unit, Receive an RRC connection release message including a synchronization cell list for at least one synchronization cell from a data cell on which an RRC (radio resource control) connection is performed, Transitioning to RRC inactive mode, From the synchronization cell, a synchronization cell SSB (synchronization signal block) or a synchronization cell SIB (system information block) is received, A selection procedure or a reselection procedure for a synchronization cell is performed based on the above synchronization cell SSB or the above synchronization cell SIB, At least one data cell associated with the synchronization cell transmits a wake-up signal, A terminal configured to receive a data cell SSB or a data cell SIB from at least one of the data cells that have received the wake-up signal.

13. In paragraph 12, The above synchronization cell is a cell that always operates in an active state and supports paging functions for terminals. The above data cell is a terminal that is activated upon receipt of a wake-up signal from the terminal and is a cell that does not support a paging function for the terminal.

14. In paragraph 12, The above RRC connection release message includes lists of data cells associated with each synchronization cell included in the synchronization cell list or lists of data area codes set for each synchronization cell. A terminal wherein the above data area code is associated with at least one data cell.

15. In paragraph 12, The above control unit, After transitioning to the RRC inactive mode, a timer for searching for data cells is started, The terminal is further configured to stop the timer and initiate an RRC connection resumption procedure to the selected data cell if a data cell is selected before the above timer expires.

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