Terminal and first base station in wireless communication system and method performed by same

Abstract

The present disclosure relates to a terminal and a first base station in a wireless communication system and a method performed by the same. A method performed by a terminal in a wireless communication system includes: receiving, from a first base station, a radio resource control (RRC) message for configuring a dual connectivity (DC) for the terminal, in which the first base station is a primary cell group (MCG) operation of the DC and a second base station is a secondary cell group (SCG) operation of the DC; receiving an RRC release message from the first base station to suspend the RRC connection; storing a configuration of the SCG in a terminal context in a case where the RRC connection is suspended; receiving an RRC recovery message from the first base station to recover the suspended RRC connection; and in a case where the RRC recovery message includes first information indicating that the configuration of the SCG is maintained, maintaining the configuration of the SCG stored in the terminal context based on the first information.

Description

[0001] This application is a divisional application of an invention patent application with an application date of May 4, 2020, application number 202080038229.8, and invention name “Method and device for supporting fast cell activation during connection recovery in the next generation mobile communication system”. Technical Field

[0002] The present disclosure relates to a method and apparatus for supporting fast cell activation in a connection recovery process in a next generation mobile communication system.

[0003] Furthermore, the present disclosure relates to a method and apparatus for efficient reception data processing of a PDCP entity (PDCP layer) in a next generation mobile communication system. Background Art

[0004] In order to meet the increasing demand for wireless data traffic since the deployment of 4G communication systems, efforts have been made to develop improved 5G or pre-5G communication systems. Therefore, 5G or pre-5G communication systems are also called "super 4G networks" or "post-LTE systems". 5G communication systems are considered to be implemented in higher frequency (millimeter wave) bands, such as the 60GHz band, in order to achieve higher data rates. In order to reduce the propagation loss of radio waves and increase the transmission distance, beamforming, massive multiple input multiple output (MIMO), full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and massive antenna technology are discussed in 5G communication systems. In addition, in 5G communication systems, system network improvements are being developed based on advanced small cells, cloud radio access networks (RAN), ultra-dense networks, device-to-device (D2D) communications, wireless backhaul, mobile networks, collaborative communications, coordinated multi-point (CoMP), receiving-end interference elimination, etc. In 5G systems, hybrid FSK and QAM modulation (FQAM) and sliding window superposition coding (SWSC) have been developed as advanced coded modulation (ACM), and filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA) and sparse code multiple access (SCMA) as advanced access technologies.

[0005] The Internet, a human-centered connected network in which humans generate and consume information, is now evolving toward the Internet of Things (IoT), in which distributed entities (such as things) exchange and process information without human intervention. The Internet of Everything (IoE) has emerged, which is a combination of IoT technology and big data processing technology through connection with cloud servers. As IoT implementation requires technical elements such as "sensing technology", "wired / wireless communication and network infrastructure", "service interface technology" and "security technology", sensor networks, machine-to-machine (M2M) communication, machine-type communication (MTC), etc. have been recently studied. Such an IoT environment can provide intelligent Internet technology services to create new value for human life by collecting and analyzing data generated between connected things. IoT can be applied to various fields, including smart homes, smart buildings, smart cities, smart cars or connected cars, smart grids, healthcare, smart appliances, and advanced medical services, through the integration and combination of existing information technology (IT) with various industrial applications.

[0006] In line with this, various attempts have been made to apply 5G communication systems to IoT networks. For example, technologies such as sensor networks, machine type communications (MTC), and machine-to-machine (M2M) communications can be implemented through beamforming, MIMO, and array antennas. Cloud radio access network (RAN) as an application of the above-mentioned big data processing technology can also be considered as an example of the fusion of 5G technology and IoT technology. The above information is provided only as background information to assist in understanding the present disclosure. No determination has been made and no assertion has been made as to whether any of the above can be applied to the present disclosure as prior art. Summary of the invention

[0007]

Technical issues

[0008] In order to support services with high data transmission rate and low transmission delay in the next generation mobile communication system, the base station needs to quickly configure the carrier aggregation (CA) technology or the dual connection (DC) technology for the terminal. However, the frequency measurement result of the terminal is required to configure the technology for the terminal. Therefore, a method capable of quickly receiving the terminal frequency measurement result report is required. In addition, in the case where the base station switches the RRC connection mode terminal to the RRC inactive mode for a specified reason, the terminal and the base station need to store the configuration information on the PCcell or SCell of the carrier aggregation technology or the configuration information on the primary cell group (MCG) (PCcell or SCell) of the dual connection technology or the configuration information on the secondary cell group (SCG) (PSCell or SCell), and quickly activate the carrier aggregation technology or the dual connection technology during the RRC connection recovery process.

[0009] In addition, when the terminal and the base station send or receive data in the next generation mobile communication system, the function of enhancing security to prevent data errors according to the channel environment and external attacks can be implemented in the PDCP entity (PDCP layer). Therefore, the receiving operation of the PDCP entity (PDCP layer) should be effectively designed according to the enhancement of security.

[0010]

Problem Solution

[0011] The disclosed content for solving the above-mentioned problem relates to a method of a terminal in a wireless communication system, the method comprising: performing decryption and integrity verification of first data by a PDCP entity of the terminal; in the event that the integrity verification of the first data fails, indicating the integrity verification failure to a higher layer; and discarding the first data, and considering that the first data has not yet been received.

[0012] In addition, the disclosure for solving the above-mentioned problem relates to a method of a base station in a wireless communication system, the method comprising: performing decryption and integrity verification on received first data by a PDCP entity of the base station; in case the integrity verification of the first data fails, indicating the integrity verification failure to a higher layer; and discarding the first data and considering that the first data has not yet been received.

[0013] In addition, the disclosure for solving the above-mentioned problem relates to a terminal in a wireless communication system, which terminal includes: a transceiver; and a controller, wherein the controller is configured to: perform decryption and integrity verification on received first data by a PDCP entity of the terminal; in the event that the integrity verification of the first data fails, indicate the integrity verification failure to a higher layer; and discard the first data and consider that the first data has not yet been received.

[0014] In addition, the disclosure for solving the above-mentioned problem relates to a base station in a radio communication system, which base station includes: a transceiver; and a controller, wherein the controller is configured to: perform decryption and integrity verification on received first data by a PDCP entity of the base station; in the event that the integrity verification of the first data fails, indicate the integrity verification failure to a higher layer; and discard the first data and consider that the first data has not yet been received.

[0015] [Advantageous Effects of the Invention]

[0016] The present disclosure proposes a method, in which, in a next-generation mobile communication system, a terminal in RRC idle mode or RRC inactive mode can quickly report peripheral frequency measurement results to a base station, so that the base station can quickly configure a carrier aggregation technology or a dual connectivity technology for the terminal. Specifically, before the terminal configures a connection with a network, the terminal can perform frequency measurement based on pre-configured frequency configuration information, and once the connection with the network is configured, the terminal can report the frequency measurement results, so that the carrier aggregation (CA) technology or the dual connectivity (DC) technology can be quickly configured for the terminal.

[0017] In addition, the present disclosure specifically proposes a method in which, when the base station switches the RRC connected mode terminal to the RRC inactive mode for a specified reason, the terminal and the base station can store configuration information about the PCcell or SCell of the carrier aggregation technology or configuration information about the MCG (PCcell or SCell) of the dual connection technology or configuration information about the SCG (PSCell or SCell), and the carrier aggregation technology or the dual connection technology can be quickly activated during the RRC connection recovery process by using it during the RRC connection recovery process without discarding the configuration information, thereby reducing signaling overhead and increasing the data transmission rate faster.

[0018] Before proceeding to the following detailed description, it may be helpful to set forth definitions of certain words and phrases used throughout this patent document: the terms "include" and "comprising" and their derivatives mean inclusion without limitation; the term "or" is inclusive, meaning and / or; the phrases "associated" and "associated with" and their derivatives may mean including, included, interconnected, containing, contained within, connected to or coupled to, communicable with, cooperating with, interleaved, juxtaposed, proximate, bound to, or having, having the property of, etc.; and the term "controller" means any device, system, or portion thereof that controls at least one operation, such device being implemented in hardware, firmware, or software, or some combination of at least two thereof. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether local or remote.

[0019] In addition, the various functions described below can be implemented or supported by one or more computer programs, each of which is formed by a computer-readable program code and contained in a computer-readable medium. The terms "application" and "program" refer to one or more computer programs, software components, instruction sets, processes, functions, objects, classes, instances, related data or parts thereof suitable for implementation in a suitable computer-readable program code. The phrase "computer-readable program code" includes any type of computer code, including source code, object code and executable code. The phrase "computer-readable medium" includes any type of medium that can be accessed by a computer, such as a read-only memory (ROM), a random access memory (RAM), a hard drive, a compact disk (CD), a digital video disk (DVD) or any other type of memory. "Non-transitory" computer-readable media does not include wired, wireless, optical or other communication links that transmit temporary electrical signals or other signals. Non-transitory computer-readable media include media that can permanently store data and media that can store data and rewrite it later, such as rewritable optical disks or erasable storage devices.

[0020] Definitions for certain words and phrases are provided throughout this patent document, those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] For a more complete understanding of the present disclosure and its advantages, reference is now made to the following description in conjunction with the accompanying drawings, wherein like reference numerals represent like parts:

[0022] Figure 1A A diagram showing a structure of an LTE system to which the present disclosure is applicable;

[0023] Figure 1B A diagram showing a radio protocol structure in an LTE system to which the present disclosure is applicable is shown;

[0024] Figure 1C A diagram showing a structure of a next-generation mobile communication system to which the present disclosure is applicable;

[0025] Figure 1D A diagram showing a radio protocol structure of a next-generation mobile communication system to which the present disclosure is applicable is shown;

[0026] Figure 1E A diagram showing a process in which a terminal switches from an RRC idle mode or an RRC inactive mode to an RRC connected mode and configures a carrier aggregation technology in a next generation mobile communication system of the present disclosure is shown;

[0027] Figure 1FA view showing a first embodiment is shown, wherein in the next generation mobile communication system of the present disclosure, a terminal is allowed to perform early frequency measurement in an RRC idle mode or an RRC inactive mode and quickly report the frequency measurement result;

[0028] Figure 1G A block diagram showing a configuration of a TRP in a radio communication system to which the embodiment is applicable;

[0029] Figure 1H A view showing a second embodiment is shown, wherein in the next generation mobile communication system of the present disclosure, a terminal is allowed to perform early frequency measurement in an RRC idle mode or an RRC inactive mode and quickly report the frequency measurement result;

[0030] Fig. 1I A diagram showing the operation of a terminal for performing a frequency measurement report method based on a short cycle proposed by the present disclosure;

[0031] Figure 1J The structure of a terminal to which the embodiments can be applied is shown;

[0032] Figure 2A A diagram showing a structure of an LTE system to which the present disclosure is applicable;

[0033] Figure 2B A diagram showing a radio protocol structure in an LTE system to which the present disclosure is applicable is shown;

[0034] Figure 2C A diagram showing a structure of a next-generation mobile communication system to which the present disclosure is applicable;

[0035] Figure 2D A diagram showing a radio protocol structure of a next-generation mobile communication system to which the present disclosure is applicable is shown;

[0036] Figure 2E A view is shown explaining a process in which a base station releases a connection of a terminal so that the terminal switches from an RRC connected mode to an RRC idle mode and a process in which a terminal configures a connection with a base station so as to switch from an RRC idle mode to an RRC connected mode in the present disclosure;

[0037] Figure 2F A diagram showing security issues that may occur in a first embodiment of the operation of a receiving PDCP entity (PDCP layer) (receiving PDCP entity or receiving PDCP layer) of the present disclosure is shown;

[0038] Figure 2G A diagram showing an embodiment of an efficient PDCP entity (PDCP layer) proposed by the present disclosure is shown;

[0039] Figure 2HA diagram showing the operation of a PDCP entity (PDCP layer) of a receiving terminal proposed in the present disclosure is shown;

[0040] Fig.2I shows the structure of a terminal or a radio node to which the embodiments are applicable; and

[0041] Figure 2J A block diagram showing the configuration of a TRP or a radio node in a radio communication system to which the embodiments are applicable. DETAILED DESCRIPTION

[0042] Discussed below Figures 1A to 2J The various embodiments used to describe the principles of the present disclosure in this patent document are merely exemplary and should not be interpreted in any way to limit the scope of the present disclosure. Those skilled in the art will appreciate that the principles of the present disclosure can be implemented in any appropriately arranged system or device.

[0043] Hereinafter, the operating principle of the present disclosure will be described in detail in conjunction with the accompanying drawings. In the following description of the present disclosure, when it may make the subject matter of the present disclosure quite unclear, the detailed description of the known functions or configurations incorporated herein will be omitted. The terms to be described below are defined in consideration of the functions in the present disclosure, and may differ depending on the user, the user's intention or habit. Therefore, the definition of the terms should be based on the content of the entire specification.

[0044] When describing the embodiments of the present disclosure, descriptions related to technical contents known in the art and not directly related to the present disclosure will be omitted. Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0045] In the following description, for the sake of convenience, terms used to identify access nodes, terms related to network entities, terms related to messages, terms related to interfaces between network entities, terms related to various identification information, etc. are illustratively used. Therefore, the present disclosure is not limited to the terms used below, and other terms related to subjects with equivalent technical meanings may be used.

[0046] In the following description, for ease of description, the present disclosure uses terms and names defined in the 3rd Generation Partnership Project Long Term Evolution (3GPP LTE) standard. However, the present disclosure is not limited to these terms and names, and can be applied to systems conforming to other standards in the same manner. In the present disclosure, the term "eNB" can be used interchangeably with the term "gNB". That is, a base station described as an "eNB" can indicate a "gNB".

[0047] The present disclosure proposes a method, in which an RRC inactive mode terminal can perform frequency measurement before configuring an RRC connection with a network, and can quickly report the frequency measurement result when configuring the RRC connection or after configuring the RRC connection, so that the base station can quickly configure carrier aggregation (CA) technology or dual connection (DC) technology for the terminal.

[0048] In the present disclosure, a terminal for which a carrier aggregation (CA) technology or a dual connectivity (DC) technology is configured is considered, and a proposed method is specified using the following terms.

[0049] -Primary Cell (PCell): refers to the serving cell used when the terminal first configures a connection with a base station, and the connection can be configured by sending or receiving a primary RRC message using the PCell. In addition, since the PCell always has PUCCH transmission resources, the PCell can indicate HARQ ACK or NACK, can always have configured uplink and downlink, and can be used as a reference cell for timing adjustment (timing advance, primary timing advance group (pTAG)). For example, after the PCell is configured, since the carrier aggregation technology is configured, when the SCell is added, the SCell can refer to the timing adjustment value of the PCell to perform uplink data transmission. In addition, when the dual connection technology is configured, the PCell may mean the PCell of the MCG.

[0050] -MCG: refers to a group of cells supported by a base station or a serving cell. The terminal first configures a connection with the base station for it. When dual connectivity technology is configured, the main RRC messages are sent or received through the MCG.

[0051] -Secondary Cell Group (SCG): After the terminal configures the connection with the base station, in addition to the MCG, the terminal can also add the cell of another base station, where a group of cells supported in another base station means SCG, and when the dual connection technology is configured, the SCG can be added to increase the data transmission rate or effectively support the mobility of the terminal.

[0052] -Primary Secondary Cell (PSCell): When the terminal configures a connection with a base station and adds a group of cells of another base station outside the MCG, and configures dual connectivity technology, the cell corresponding to the PCcell in the SCG is called the PSCell.

[0053] -Secondary Cell (SCell): After the terminal first configures the connection with the base station, the cell additionally configured by the base station to configure the carrier aggregation technology is called SCell. The SCell may have PUCCH transmission resources according to the configuration of the base station, may have an uplink or downlink configured according to the configuration of the base station, and may be used as a reference cell for timing adjustment (timing advance, according to the secondary timing advance group (sTAG)) according to the configuration of the base station. For example, in the case where the SCell is added after the PCell is configured and the sTAG is configured as the carrier aggregation technology, other SCells of the sTAG may refer to the timing adjustment value of the specified SCell to perform uplink data transmission. In addition, in the case of configuring dual connection technology for the terminal, the SCell may refer to an SCell other than the PCell of the MCG, or an SCell other than the PSCell of the SCG.

[0054] The present disclosure proposes a method in which, when a base station applies a carrier aggregation technology or a dual connectivity technology to a terminal, the carrier aggregation technology or the dual connectivity technology can be quickly activated.

[0055] For example, the base station may configure frequency configuration information for the terminal as an RRCRelease message and a state transfer indicator (e.g., an indication of transfer to RRC idle mode or an indication of transfer to RRC inactive mode (e.g., suspend configuration)) to allow frequency measurement to be performed in RRC idle mode or RRC inactive mode, or the frequency configuration information may be sent through system information. The terminal may receive the frequency configuration information to perform frequency measurement in RRC idle mode or RRC inactive mode, and may later configure or restore the connection with the network to report the frequency measurement result to the base station when switching to RRC connected mode, so that the base station may quickly configure or activate the carrier aggregation technology or the dual connection technology based on the frequency measurement result.

[0056] In addition, the present disclosure proposes a channel measurement report (short CSI report) method based on a short period when activating PCell, SCell or PSCell by configuring MAC CE or RRC message, so that the terminal can quickly report the channel measurement for the activated PCell, SCell or PSCell to the base station within a short period, thereby allowing the base station to quickly allocate transmission resources to the terminal based on this, and data transmission / reception can start quickly. The base station configures a channel measurement report with a short period for the terminal (for example, using the configuration of RRCReconfiguration, RRCResume or RRCSetup message) may mean that the base station temporarily or continuously sends a signal with a short period according to the period configured for the terminal. That is, the base station can temporarily or continuously send a short period signal for channel measurement, and configure and notify the terminal of the short period, so that the terminal can measure the signal for channel measurement and report the measurement to the base station. The base station can also configure uplink transmission resources or periodic or cyclic transmission resources, and the terminal reports the signal or channel measurement result through this resource.

[0057] The configuration information of the channel measurement reporting method based on a short cycle can be configured by the base station through an RRC message. At this time, the configuration information can be configured to include at least one of the following information: the measurement period of the measurement channel; the transmission resources used to report the measurement results (for example, PUCCH transmission resources, specific subframe numbers that can report transmission resources, etc.); frequency information to be measured; a signal strength critical value that can be determined by a cell identifier or a valid measurement result (for example, a signal strength greater than the critical value can be determined as a valid measurement result); a measurement method; or when the time point for executing the RRC message is n (for example, subframe n), the value of X and the value of Y (for example, subframe, TTI or symbol unit) for performing frequency channel measurement reports between n+X and n+Y based on a short cycle.

[0058] In addition, in the present disclosure, the base station can directly configure the active, inactive or idle state of the SCell or PSCell via an RRC message.

[0059] In addition, in the present disclosure, when the terminal switches to the RRC inactive mode, the PCell, SCell or PSCell configuration information that has been configured for the RRC connected mode terminal can be stored as terminal context information. In addition, in the present disclosure, when the terminal later starts the RRC connection recovery process to configure the connection with the network, the PCell, SCell or PSCell configuration information can be used for fast service cell activation, fast carrier aggregation technology activation or fast dual connection technology activation without being discarded. When the terminal sends an RRCRelease message for indicating a transition to the RRC inactive mode, the base station can provide the terminal with an indication of an indicator for indicating whether the terminal should discard or store each PCell, SCell or PSCell configuration information.

[0060] For example, if the RRCRelease message does not have an indicator for the PCell, SCell or PSCell configuration information, the terminal may discard the PCell, SCell or PSCell configuration information when receiving the RRCRelease message or when performing the RRC connection recovery procedure later.

[0061] In addition, if the RRCRelease message only includes an indicator for PCell configuration information, the terminal can only store configuration information about the PCell configuration information from the PCell, SCell or PSCell configuration information, and other configuration information can be discarded when the terminal receives the RRCRelease message or when the RRC connection recovery process is performed later.

[0062] In addition, if the RRCRelease message only includes an indicator for SCell configuration information, the terminal can only store configuration information about the SCell configuration information from the PCell, SCell or PSCell configuration information, and other configuration information can be discarded when the terminal receives the RRCRelease message or when the RRC connection recovery process is performed later.

[0063] In addition, if the RRCRelease message only includes an indicator for the MCG configuration information, the terminal can only store the configuration information about the MCG (PCell or SCell) configuration information from the PCell, SCell or PSCell configuration information, and other configuration information can be discarded when the terminal receives the RRCRelease message or when the RRC connection recovery process is performed later.

[0064] In addition, if the RRCRelease message only includes an indicator for the SCG configuration information, the terminal can only store the configuration information about the SCG (PSCell or SCell) configuration information from the PCell, SCell or PSCell configuration information, and other configuration information can be discarded when the terminal receives the RRCRelease message or when the RRC connection recovery process is performed later.

[0065] In addition, if the RRCRelease message includes an indicator for MCG and SCG configuration information, the terminal can store configuration information about MCG (PCell or SCell) and SCG configuration information from PCell, SCell or PSCell configuration information. When performing the RRC connection recovery process, the stored information indicated by the indicator of the RRCRelease message will not be discarded by the terminal or base station.

[0066] As another method, when RRCRelease is received, the terminal can store all PCell, SCell or PSCell configuration information. Even when the terminal starts the RRC connection recovery process, all information will not be discarded. In addition, as proposed in the above-mentioned RRCRelease message, when the terminal performs the RRC connection recovery process and receives the RRCRelease message from the base station, an indicator of each of the PCell, SCell or PSCell configuration information can be defined for the RRCRelease message to determine whether to discard the PCell, SCell or PSCell configuration information and indicate a change in part of the configuration information, and a new indicator (e.g., fullconfig) can be used to discard all existing configuration information and indicate a completely new configuration.

[0067] In addition, in the present disclosure, as described above, when the terminal stores PCell, SCell or PSCell configuration information and uses the configuration information for the RRC connection recovery process, the base station can directly configure the activity state of the SCell or PSCell through the RRCResume message, so that the carrier aggregation technology or dual connection technology can be quickly configured or activated. When the RRCrescume message is received, when the RRCrescume message indicates the activity state of the SCell or PSCell, the terminal can use the short-cycle-based channel measurement reporting method proposed in the present disclosure. In addition, when the RRCResume message is received, the terminal can also apply the short-cycle-based channel measurement reporting method to the serving cell, i.e., the PCell.

[0068] In addition, in the present disclosure, when the PCell, SCell, PSCell or part of the bandwidth configured for the cell (PCell, SCell or PSCell) is activated by the configuration of the MAC CE or RRC message, triggered by L1 signaling (e.g., downlink control information (DCI) of the PDCCH), or an indication of partial bandwidth switching is provided, a channel measurement report (short channel state information (CSI) report or short channel quality information (CQI) report) method based on a short period is proposed, so that the terminal can quickly perform a channel measurement report to the base station, and the channel measurement report is based on the short period of the activated PCell, SCell, PSCell or the part of the bandwidth configured for the cell. Therefore, the base station can quickly allocate transmission resources to the terminal based on this, and data transmission / reception can start quickly.

[0069] As another method, when a cell or a portion of bandwidth is activated, not only a channel measurement report method based on a short cycle is applied, but also a new state (e.g., an idle state) is defined for the cell or the portion of bandwidth. Therefore, after transitioning to a new state, the cell or portion of bandwidth can be managed so that in an inactive state, although the PDCCH is not read, the channel measurement report is continuously performed. For each cell, the base station can configure the terminal through an RRC message or indicate to the terminal through a partial bandwidth identifier the partial bandwidth for supporting the idle state, and for each cell, the base station can indicate to the terminal the partial bandwidth supporting a separate idle state by using L1 signaling (DCI of PDCCH) or MAC CE or RRC message. Therefore, fast activation of cells and fast data transmission / reception can be supported.

[0070] As another method, the base station can indicate whether the terminal should perform PDCCH monitoring for each cell by using L1 signaling (DCI of PDCCH) or MAC CE or RRC message, and can prevent the terminal from unnecessarily reading the PDCCH of all cells (PCell, SCell or PSCell), thereby saving the terminal's battery.

[0071] As another method, the base station can indicate via L1 signaling (DCI of PDCCH) or MAC CE or RRC message whether the terminal should perform channel measurement reporting for each cell, and can allow the terminal to perform channel measurement reporting to the indicated cell (PCell, SCell or PSCell) even in an inactive state, thereby supporting fast activation or fast data sending / reception for each cell.

[0072] Figure 1A A diagram showing a structure of an LTE system to which the present disclosure is applicable.

[0073] refer to Figure 1AAs shown therein, the radio access network of the LTE system is composed of a next generation base station (evolved node B, hereinafter referred to as ENB, node B or base station) 1a-05, 1a-10, 1a-15 or 1a-20, a mobility management entity (MME) 1a-25 and a serving gateway (S-GW) 1a-30. User equipment (hereinafter referred to as UE or terminal) 1a-35 accesses an external network through ENB 1a-05 to 1a-20 and S-GW 1a-30.

[0074] exist Figure 1A In the LTE system, ENB 1a-05 to 1a-20 correspond to the existing Node B of the UMTS system. The ENB is connected to the UE 1a-35 through a radio channel and performs a more complex role than the existing Node B. Since in the LTE system, all user services and real-time services using the Internet Protocol (such as voice over IP, (VoIP)) are served through a shared channel, a device that performs scheduling by collecting status information (such as buffer status, available transmission power status, and channel status of the UE) is required, and the ENB 1a-05 to 1a-20 are used as the device. One ENB generally controls multiple cells. For example, in order to achieve a transmission speed of 100Mbps, the LTE system uses an orthogonal frequency division multiplexing (hereinafter referred to as OFDM) scheme as a wireless access technology, for example, in a bandwidth of 20MHz. In addition, an adaptive modulation and coding (hereinafter referred to as AMC) scheme for determining a modulation scheme and a channel coding rate according to the channel status of the terminal is applied. The S-GW 1a-30 is a device for providing a data bearer, and generates or removes a data bearer according to the control of the MME 1a-25. The MME is a device responsible for various control functions of a terminal and a mobility management function, and is connected to a plurality of base stations.

[0075] Figure 1B A diagram showing a radio protocol structure in an LTE system to which the present disclosure is applicable is shown.

[0076] refer to Figure 1B In each of the terminal and the ENB, the radio protocol of the LTE system includes a packet data convergence protocol (PDCP) 1b-05 or 1b-40, a radio link control (RLC) 1b-10 or 1b-35, and a medium access control (MAC) 1b-15 or 1b-30. The packet data convergence protocol (PDCP) 1b-05 or 1b-40 is responsible for operations such as IP header compression / recovery. The main functions of PDCP are summarized as follows.

[0077] -Header compression and decompression function (Header compression and decompression: ROHC only).

[0078] -User data transmission function (user data transmission)

[0079] - In-sequence delivery function (deliver higher layer PDUs in sequence during the PDCP re-establishment procedure for RLC AM).

[0080] - Resequence function (split bearer for DC (supports RLC AM only): PDCP PDU routing for transmission, PDCP PDU reordering for reception)

[0081] - Overlap detection function (repeated detection of lower layer SDUs during PDCP re-establishment procedure for RLC AM).

[0082] - Retransmission function (for split bearers in DC, retransmit PDCP SDU at handover; for RLC

[0083] AM, retransmitting PDCP PDU during PDCP data recovery process).

[0084] -Encryption and decryption functions.

[0085] - Timer-based SDU removal functionality (timer-based SDU discard in uplink).

[0086] The radio link controller (hereinafter referred to as RLC) 1b-10 or 1b-35 reconfigures a PDCP packet data unit (PDU) to have an appropriate size, and performs an ARQ operation, etc. The main functions of the RLC are summarized as follows.

[0087] - Data transfer function (transmission of higher layer PDUs).

[0088] -ARQ functionality (error correction via ARQ (applicable only to AM data transmission)).

[0089] - Concatenation, segmentation and reassembly function (concatenation, segmentation and reassembly of RLC SDU (applicable only to UM and AM data transmission)).

[0090] - Re-segmentation function (resegmentation of RLC data PDU (applicable only for AM data transmission)).

[0091] - Resequence reordering function (reordering of RLC data PDUs (applicable only to UM and AM data transmission)).

[0092] - Overlap detection function (duplicate detection (applicable only for UM and AM data transmission)).

[0093] - Error detection function (protocol error detection (only for AM data transmission)).

[0094] - RLC SDU removal function (RLC SDU discard (only for UM and AM data transmission)).

[0095] -RLC re-establishment function.

[0096] MAC 1b-15 or 1b-30 is connected to a plurality of RLC entities (or RLC layers) configured in one terminal, and performs operations of multiplexing RLC PDUs to MAC PDUs and demultiplexing RLC PDUs from MAC PDUs. The main functions of MAC are summarized as follows.

[0097] - Mapping function (mapping between logical channels and transport channels).

[0098] - Multiplexing and demultiplexing functionality (multiplexing and demultiplexing MAC SDUs belonging to one or more different logical channels into transport blocks transmitted to or from the physical layer via transport channels).

[0099] -Scheduling information reporting function.

[0100] -HARQ function (error correction through HARQ)

[0101] - Function to adjust the priority between logical channels (priority handling between logical channels of a UE).

[0102] -Function of adjusting the priority between terminals (processing the priority between UEs through dynamic scheduling).

[0103] -MBMS service identification function.

[0104] -Transmission format selection function (transmission format selection)

[0105] - Fill function.

[0106] The physical layer 1b-20 or 1b-25 performs operations of performing channel coding and modulation on higher layer data to generate OFDM symbols therefrom and sending the OFDM symbols to a radio channel, or performs demodulation and channel decoding on OFDM symbols received through a radio channel and transmits the demodulated and channel-decoded symbols to a higher layer.

[0107] Figure 1C A diagram showing a structure of a next-generation mobile communication system to which the present disclosure is applicable.

[0108] refer to Figure 1CAs shown therein, the radio access network of the next generation mobile communication system (hereinafter, NR or 5G) is composed of a next generation base station (new radio node B, hereinafter, NR gNB or NR base station) 1c-10 and a new radio core network (NRCN) 1c-05. The new radio user equipment (hereinafter referred to as NR UE or terminal) 1c-15 accesses the external network through the NR gNB 1c-10 and NRCN 1c-05.

[0109] exist Figure 1C In the present invention, NR gNB 1c-10 corresponds to the evolved Node B (eNB) of the existing LTE system. NR gNB is connected to UE 1c-15 through a radio channel and can provide better services than those of the existing Node B. Since all user services are served through shared channels in the next generation mobile communication system, a device is required to perform scheduling by collecting status information such as buffer status, available transmission power status, and channel status of UE, and NR NB1c-10 acts as the device. One NR gNB generally controls multiple cells. Compared with the current LTE, in order to achieve ultra-high-speed data transmission, the existing maximum bandwidth or larger bandwidth can be included, and beamforming technology can be additionally grafted by using an orthogonal frequency division multiplexing (OFDM) scheme as a radio access technology. In addition, an adaptive modulation and coding (hereinafter referred to as AMC) scheme for determining the modulation scheme and channel coding rate according to the channel status of the terminal is applied. NR-CN 1c-05 performs functions such as mobility support, bearer configuration, QoS configuration, etc. NR-CN is a device responsible for various control functions of the terminal and mobility management functions, and is connected to multiple base stations. In addition, the next generation mobile communication system can be linked with the existing LTE system, and the NR CN is connected to the MME 1c-25 through a network interface. The MME is connected to the existing base station eNB 1c-30.

[0110] Figure 1D A diagram showing a radio protocol structure of a next-generation mobile communication system to which the present disclosure is applicable is shown.

[0111] refer to Figure 1D The radio protocol of the next generation mobile communication system includes NRSDAP 1d-01 or 1d-45, NR PDCP 1d-05 or 1d-40, NR RLC 1d-10 or 1d-35, and NR MAC 1d-15 or 1d-30 in each of the terminal and the NR base station.

[0112] The main functions of NR SDAP 1d-01 or 1d-45 may include some of the following functions.

[0113] - User data transfer function (transmission of user plane data).

[0114] - Functionality of mapping uplink and downlink QoS flows and data bearers (mapping between QoS flows and DRBs for both DL and UL).

[0115] - Functionality to mark QoS Flow ID for uplink and downlink (mark QoS Flow ID in both DL and UL packets).

[0116] - Functionality for mapping the Reflective QoS flow of uplink SDAP PDU to data bearer (Mapping of Reflective QoS flow of UL SDA PDU to DRB).

[0117] Regarding the SDAP entity (or SDAP layer), whether to use the header of the SDAP entity or whether to use the function of the SDAP entity can be configured for the terminal through an RRC message for each PDCP entity (PDCP layer), each bearer, or each logical channel, and in the case where the SDAP header is configured, the NAS QoS reflection configuration 1-bit indicator (NAS reflection QoS) and the AS QoS reflection configuration 1-bit indicator (AS reflection QoS) of the SDAP header can provide an indication to the terminal so that the terminal can update or reconfigure the mapping information on the data bearer and QoS flow of the uplink and downlink. The SDAP header may include QoS flow ID information indicating QoS. QoS information can be used as data processing priority, scheduling information, etc. to support active services.

[0118] The main functions of NR PDCP 1d-05 or 1d-40 may include part of the following functions.

[0119] -Header compression and decompression function (Header compression and decompression: ROHC only).

[0120] -User data transmission function (transmission of user data).

[0121] - In-sequence delivery function (in-sequence delivery of higher layer PDUs).

[0122] - Out-of-sequence delivery functionality (out-of-order delivery of higher layer PDUs).

[0123] - Resequence reordering function (for reordering of received PDCP PDUs).

[0124] - Overlap detection functionality (duplicate detection of lower layer SDUs).

[0125] -Retransmission function (retransmission of PDCP SDU).

[0126] -Encryption and decryption functions.

[0127] - Timer-based SDU removal functionality (timer-based SDU discard in uplink).

[0128] The sequence reordering function (reordering) for the NR PDCP device refers to the function of reordering the PDCP PDU received from the lower layer based on the PDCP sequence number (SN) order, which may include the function of delivering data to the higher layer in the reordered sequence or the function of directly delivering data without considering the sequence, which may include the function of recording the lost PDCP PDU by reordering the sequence, which may include the function of reporting the status of the lost PDCP PDU to the transmitter side, and which may include the function of requesting retransmission of the lost PDCP PDU.

[0129] The main functions of NR RLC 1d-10 or 1d-35 may include some of the following functions.

[0130] - Data transfer function (transmission of higher layer PDUs).

[0131] - In-sequence delivery function (in-sequence delivery of higher layer PDUs).

[0132] - Out-of-sequence delivery functionality (out-of-order delivery of higher layer PDUs).

[0133] -ARQ function (error correction through ARQ).

[0134] - Concatenation, segmentation and reassembly function (concatenation, segmentation and reassembly of RLC SDU).

[0135] - Re-segmentation function (resegmentation of RLC data PDU).

[0136] - Resequence reordering function (reordering of RLC data PDUs).

[0137] - Overlap detection function (duplicate detection).

[0138] - Error detection function (protocol error detection).

[0139] - RLC SDU removal function (RLC SDU discard).

[0140] - RLC re-establishment function (RLC Re-establishment).

[0141] The sequential delivery function of the NR RLC device refers to a function of sequentially delivering the RLC SDU received from the lower layer to the higher layer, and may have the following functions: in the case where the original one RLC SDU is received separately as multiple RLC SDUs, reassembling and delivering the RLC SDU, which may include a function of rearranging the received RLC PDU based on the RLC sequence number (SN) or the PDCP sequence number (SN), which may include a function of recording the lost RLC PDU by rearranging the sequence, which may include a function of reporting the status of the lost RLC PDU to the transmitter side, which may include a function of requesting retransmission of the lost RLC PDU, and which may include a function of sequentially delivering the RLC PDU only before the lost RLC SDU to the higher layer in the presence of the lost RLC SDU, if a specified timer expires, the function of sequentially delivering to the higher layer all RLC SDUs received before the start of the timer despite the presence of the lost RLC SDU, or, if a specified timer expires, the function of sequentially delivering to the higher layer all RLC SDUs that have been received until the current time despite the presence of the lost RLC SDU. In addition, the RLC PDU can be processed in the order in which the RLC PDU is received (in the order of arrival, regardless of the order of sequence numbers) and can be delivered to the PDCP device regardless of the sequence number (out-of-order delivery). In the case of segmentation, segments stored in the buffer or to be received later can be received, reconstructed into a complete RLC PDU, processed and delivered to the PDCP device. The NRRLC layer may not include a cascading function. This function may be performed in the NR MAC layer or may be replaced by a multiplexing function of the NR MAC layer.

[0142] The non-sequential delivery function (out-of-order delivery) of the NR RLC device refers to a function of directly delivering the RLC SDU received from a lower layer to a higher layer without considering the sequence, and may include a function of reassembling and transmitting the RLC SDU when the original one RLC SDU is received separately as multiple RLC SDUs, and may include a function of storing the RLC SN or PDCP SN of the received RLC PDU and arranging the sequence to record the lost RLC PDU.

[0143] NR MAC 1d-15 or 1d-30 can be connected to multiple NR RLC entities configured in one terminal, and the main functions of NR MAC may include part of the following functions.

[0144] - Mapping function (mapping between logical channels and transport channels).

[0145] -Multiplexing and demultiplexing functions (multiplexing / demultiplexing of MAC SDU).

[0146] -Scheduling information reporting function.

[0147] -HARQ functionality (error correction via HARQ).

[0148] - Function to adjust the priority between logical channels (priority handling between logical channels of a UE).

[0149] -Function of adjusting the priority between terminals (processing the priority between UEs through dynamic scheduling).

[0150] -MBMS service identification function.

[0151] -Transmission format selection function (Transmission format selection).

[0152] - Fill function.

[0153] The NR PHY layer 1d-20 or 1d-25 performs an operation of performing channel coding and modulation on higher layer data to generate OFDM symbols therefrom and sending the OFDM symbols to a radio channel, or performs demodulation and channel decoding on OFDM symbols received through a radio channel and transmits the demodulated and channel-decoded symbols to a higher layer.

[0154] In the next generation mobile communication system, the terminal performs frequency measurement while performing a cell reselection process in RRC idle mode. The frequency measured when performing the cell reselection process may mean intra-frequency measurement or serving cell or PCell measurement of the frequency configured by the base station or sent from the pre-occupied cell. However, in addition to the intra-frequency measurement or serving cell measurement, the terminal does not perform inter-frequency measurement, and the frequency measurement results are not reported separately to the network.

[0155] That is, in the case where the terminal first performs a cell reselection process, finds a suitable cell, and performs an RRC connection configuration process after pre-occupation to switch to an RRC connection mode, the base station can configure which frequencies (e.g., a frequency list) or which frequency bands to be measured for the RRC connection mode terminal, wherein the sequence measurement is to be performed by the priority configured for each frequency, which beam is to be measured, which filtering method is used to measure the strength of the frequency when measuring the frequency (e.g., L1 filtering, L2 filtering, or L3 filtering method, or which coefficient is used and which calculation method is used for measurement), under which event or condition to start measurement when measuring the frequency, under which standard to perform measurement compared to the current serving cell (or the current pre-occupied frequency), under which event or condition to report the measured frequency result, which standard or condition should be met to report the frequency compared to the current serving cell (or the current pre-occupied frequency), at which period to report the frequency measurement result, etc. The terminal measures the corresponding frequency according to the frequency configuration configured by the base station as described above, and reports the frequency measurement result to the base station according to the corresponding event or condition. In addition, the base station can determine whether to apply the carrier aggregation technology or the dual connection technology by using the frequency measurement result received from the terminal.

[0156] The present disclosure proposes a method, wherein, in a next generation mobile communication system, a terminal can perform frequency measurement in an RRC idle mode or an RRC inactive mode terminal before switching to an RRC connected mode, can indicate the measurement result to a base station when configuring a connection with a network, and can quickly report the frequency measurement result after entering the RRC connected mode. Based on the method, for the terminal, the base station can quickly configure a carrier aggregation technology or a dual connection technology based on the result of the measurement of the terminal in the RRC idle mode or the RRC inactive mode.

[0157] Specifically, when an RRC connection mode terminal that has been configured with a connection to a network switches to an RRC idle mode or an RRC inactive mode, the base station can configure information about the frequency to be measured by the terminal in the RRC idle mode or the RRC inactive mode, information about the time (or period) for the terminal to measure the frequency in the RRC idle mode or the RRC inactive mode, or information about the area (or cell list) for the terminal to measure the frequency in the RRC idle mode or the RRC inactive mode via an RRC message, and can provide an indication to the terminal so that the terminal performs frequency measurement in the RRC idle mode or the RRC inactive mode. In addition, the present disclosure proposes an efficient terminal operation, in which each time the terminal moves, the terminal can read the system information of the new pre-occupied cell while performing a cell reselection operation, so that the terminal can perform a process about whether to continue or terminate the frequency measurement in the RRC idle mode or the RRC inactive mode, whether to extend the measurement period (for example, restart the timer), whether to report the frequency measurement result, or whether to discard the frequency measurement result according to the system information.

[0158] In the present disclosure, a bearer may be meant to include an SRB and a DRB, wherein an SRB may be meant to be a signaling radio bearer, and a DRB may be meant to be a data radio bearer. In addition, a UM DRB may be meant to be a DRB operated in an unacknowledged mode (UM) using an RLC entity, and an AM DRB may be meant to be a DRB operated in an acknowledged mode (AM) using an RLC entity.

[0159] Figure 1E A diagram illustrating a process in which a terminal switches from an RRC idle mode or an RRC inactive mode to an RRC connected mode and configures a carrier aggregation technology in a next generation mobile communication system of the present disclosure is shown.

[0160] exist Figure 1E In the present invention, for a specified reason, the base station may switch an RRC connected mode terminal that has configured a connection with the network to an RRC idle mode or an RRC inactive mode. For example, the specified reason may be a lack of scheduling resources in the base station, stopping data transmission / reception during a certain time period, etc.

[0161] In step 1e-05, the base station may send an RRCRelease message to the terminal to provide an indication to the terminal so that the terminal switches to the RRC idle mode or the RRC inactive mode.

[0162] The base station may provide an indication to the terminal through an indicator (suspend-config suspension configuration) included in the RRCRelease message, so that the terminal switches to the RRC inactive mode, and if the RRCRelease message does not include the indicator (suspend-config), the terminal may switch to the RRC idle mode.

[0163] If connection with the network is required due to specified reasons, the terminal 1e-10 that has switched to RRC idle mode or RRC inactive mode can perform RRC connection configuration by performing a random access procedure, receiving a random access response, requesting RRC connection configuration, and receiving RRC messages (1e-10, 1e-15, 1e-20, 1e-25, 1e-30, 1e-35 and 1e-40).

[0164] Through the random access procedure, the terminal can establish reverse transmission synchronization with the base station and send an RRCSetupRequest message to the base station (1e-25). The RRCSetupRequest message may include a reason (establishmentCause) for configuring a connection with the terminal identifier, etc.

[0165] The base station may send an RRCSetu message to configure the RRC connection (1e-30). The RRCSetup message may include at least one of logical channel specific configuration information, bearer specific configuration information, PDCP entity (PDCP layer) configuration information, RLC layer configuration information, and MAC layer (MAC entity) configuration information.

[0166] The RRCSetup message may allocate a bearer identifier (eg, an SRB identifier or a DRB identifier) ​​to each bearer, and may provide an indication of the PDCP layer (PDCP entity), RLC layer, MAC layer, and PHY layer configurations for each bearer.

[0167] In addition, for each bearer, the RRCConnectionSetup message can configure the length of the PDCP sequence number used in the PDCP entity (PDCP layer) (e.g., 12 bits or 18 bits), and can configure the length of the RLC sequence number used in the RLC entity (e.g., 6 bits, 12 bits, or 18 bits).

[0168] In addition, for each bearer, the RRCConnectionSetup message can provide the PDCP entity (PDCP layer) with an indication of whether to use header compression and decompression protocols in the uplink or downlink, and can indicate whether to perform integrity protection or authentication procedures. In addition, the message can indicate whether to perform a non-sequential delivery function (out-of-order delivery) in the PDCP entity (PDCP layer).

[0169] The terminal for which the RRC connection has been configured may send an RRCSetupComplete message (1e-40) to the base station. The RRCSetupComplete message may include a control message (e.g., a SERVICE REQUEST service request), through which the terminal requests the AMF or MME to configure the bearer for the specified service. The base station may send the SERVICE REQUEST message stored in the RRCConnectionSetupComplete message to the AMF or MME, and the AMF or MME may determine whether to provide the service requested by the terminal.

[0170] As a result of the determination, if it is determined that the service requested by the terminal is provided, the AMF or MME may send an INITIAL CONTEXT SETUP REQUEST message to the base station. The INITIAL CONTEXT SETUP REQUEST message may include at least one of quality of service (QoS) information to be applied when a data radio bearer (DRB) is configured, security-related information (e.g., a security key or a security algorithm) to be applied to the DRB, and the like.

[0171] In order to configure security with the terminal, the base station can send or receive a SecurityModeCommand message (security mode command message) and a SecurityModeComplete message (security mode completion message), and if the security configuration is completed, the base station can send an RRCConnectionReconfiguration message (1e-45) to the terminal.

[0172] The RRCConnectionReconfiguration message may allocate a bearer identifier (eg, an SRB identifier or a DRB identifier) ​​to each bearer, and may provide an indication of the PDCP layer (PDCP entity), RLC layer, MAC layer, and PHY layer device configurations for each bearer.

[0173] In addition, for each bearer, the RRCConnectionReconfiguration message can configure the length of the PDCP sequence number used in the PDCP entity (PDCP layer) (e.g., 12 bits or 18 bits), and can configure the length of the RLC sequence number used in the RLC entity (e.g., 6 bits, 12 bits, or 18 bits).

[0174] In addition, for each bearer, the RRCConnectionReconfiguration message can provide the PDCP entity (PDCP layer) with an indication of whether to use header compression and decompression protocols in the uplink or downlink, and can indicate whether to perform integrity protection or authentication procedures. In addition, the message can indicate whether to perform a non-sequential delivery function (out-of-order delivery) in the PDCP entity (PDCP layer).

[0175] In addition, configuration information of the DRB through which user data will be processed may be included in the RRCConnectionReconfiguration message, and the terminal may configure the DRB by applying the information and send an RRCConnectionreplacement complete message to the base station (1e-45). The base station that has completed the DRB configuration with the terminal may send an INITIAL CONTEXT SETUP COMPLETE message to the AMF or MME and may complete the connection (1e-50).

[0176] Once the above process is fully completed, the terminal can send data to the base station or receive data from the base station through the core network (1e-55 and 1e-60). According to part of the embodiment, the data transmission process may include three main steps, such as RRC connection configuration, security configuration, and DRB configuration. In addition, in order to update, add or change the configuration of the terminal for a specified reason, the base station may send an RRCConnectionReconfiguration message (1e-65).

[0177] For the RRCConnectionReconfiguration message, frequency configuration information to be measured by the terminal may be configured (eg, a list of frequencies to be measured, a period for measuring frequencies, conditions for measuring frequencies, conditions for reporting frequencies after frequency measurement, or a cell identifier for reporting frequencies).

[0178] The terminal performs frequency measurement according to the frequency measurement configuration information, and if the specified conditions are met (for example, when the signal strength of a specific frequency is greater than a certain standard (for example, a critical value) or when the signal strength of the current serving cell (frequency) is less than a certain standard (for example, a critical value)), the measured frequency measurement result can be reported to the base station (1e-60).

[0179] When receiving the frequency measurement result, the base station can send an RRCReconfiguration message 1e-65 including SCell configuration information to the terminal based on the frequency measurement result to configure an additional SCell (i.e., configure carrier aggregation technology for the terminal), and send an RRCReconfiguration message 1e-65 including secondary cell group configuration information to the terminal to configure dual connection technology for the terminal.

[0180] When the base station configures the carrier aggregation technology for the terminal, the base station can transfer the configured SCell to an active, inactive or idle state by using a MAC control element (MACCE).

[0181] The process of the base station configuring the carrier aggregation technology or dual connection technology as described above for the terminal can be summarized as follows. First, if the terminal configures a connection with the base station, and the base station configures frequency measurement configuration information for the terminal in RRC connection mode, the terminal can perform frequency measurement based on the frequency measurement configuration information, and can report the measurement result to the base station. In addition, in order to configure the carrier aggregation technology for the terminal based on the frequency measurement result of the terminal, the base station can configure the configuration information of the additional cell SCell via an RRC message, and can send a MAC CE to activate, idle or deactivate the cell. In addition, in order to configure the dual connection technology for the terminal based on the frequency measurement result of the terminal, the base station can configure the additional cell group (SCG) configuration information.

[0182] When the base station configures the carrier aggregation technology or the dual connection technology for the terminal, the terminal should first enter the RRC connection mode, receive the frequency configuration information, perform the frequency measurement, and then report the measurement result. Therefore, there is a problem that the measurement report is performed very late, so the carrier aggregation technology or the dual connection technology cannot be configured late. Therefore, in order to solve this problem, in the following disclosure, the terminal can effectively perform the frequency measurement in the RRC idle mode or the RRC inactive mode, and can report the frequency measurement result immediately after the connection with the network is configured.

[0183] The partial bandwidth can be configured via the RRCSetup message, RRCResume message 1e-30 or RRCReconfiguration message 1e-45 of the RRC connection configuration, and the RRC message can include configuration information of the PCell, PSCell or multiple SCells, and multiple partial bandwidths can be configured for each cell (PCell, PSCell or SCell).

[0184] When multiple partial bandwidths are configured for each cell, the base station can configure multiple partial bandwidths to be used in the downlink of each cell. In the case of an FDD system, multiple partial bandwidths to be used in the uplink of each cell can be configured separately from the downlink partial bandwidth. In the case of a TDD system, multiple partial bandwidths used in common in the downlink and uplink of each cell can be configured.

[0185] The information used to configure the partial bandwidth of each cell (PCell, PSCell or SCell) may include at least one of the following information.

[0186] - Downlink partial bandwidth configuration information of the cell.

[0187] ■ Initial downlink portion bandwidth (initial downlink BWP) configuration information.

[0188] ■ A plurality of partial bandwidth configuration information, and a partial bandwidth identifier (BWPID) corresponding to each partial bandwidth.

[0189] ■ A fractional bandwidth identifier for indicating a first active downlink fractional bandwidth (first active downlink BWP).

[0190] ■ A fractional bandwidth identifier used to indicate a default fractional bandwidth (Default BWP).

[0191] ■ Partial bandwidth inactivity timer configuration and timer value.

[0192] ■ A fractional bandwidth identifier used to indicate the fractional bandwidth that supports the idle state.

[0193] ■Partial bandwidth identifier, used to indicate the partial bandwidth supporting the short-cycle channel measurement reporting method.

[0194] - Uplink partial bandwidth configuration information of the cell.

[0195] ■ Initial uplink portion bandwidth (initial uplink BWP) configuration information.

[0196] ■ A plurality of partial bandwidth configuration information, and a partial bandwidth identifier (BWPID) corresponding to each partial bandwidth.

[0197] ■ A fractional bandwidth identifier for indicating a first active uplink fractional bandwidth (first active uplink BWP).

[0198] ■ A fractional bandwidth identifier used to indicate the fractional bandwidth that supports the idle state.

[0199] ■Partial bandwidth identifier, used to indicate the partial bandwidth supporting the short-cycle channel measurement reporting method.

[0200] The initial partial bandwidth (initial BWP), the default partial bandwidth (default BWP), or the first active partial bandwidth (first active BWP) configured as described above may be used for the following tasks, and may be operated as follows according to the tasks.

[0201] The initial partial bandwidth (initial BWP) can be used as a (cell-specific) partial bandwidth determined at the cell level and presented as one for each cell, and can be used as a partial bandwidth that allows synchronization of terminals, where the terminal is a terminal that first accesses the cell and can configure a connection for the cell via a random access procedure, or a terminal for which a connection has been configured. In addition, the base station can configure the initial downlink partial bandwidth (initial downlink BWP) and the initial uplink partial bandwidth (initial uplink BWP) to be used in the downlink for each cell. In addition, the configuration information of the initial partial bandwidth can be sent from the first system information (system information 1, SIB1) indicated by the CORESET, and can be reconfigured by the base station for the connected terminal through an RRC message. In addition, the initial partial bandwidth can be used after being designated as the number 0 of the partial bandwidth identifier in each of the uplink and downlink. That is, after the initial partial bandwidth is designated as the partial bandwidth identifier number 0 in the same manner, any terminal accessing the same cell can use the same initial partial bandwidth. This is because, when performing a random access procedure, the base station can send a random access response (RAR) message to the initial partial bandwidth that can be read by any terminal, and therefore may have the advantage of being conducive to a contention-based random access procedure.

[0202] The first active partial bandwidth (first active BWP) may be configured to be different for each terminal (UE-specific) and may be indicated from a plurality of partial bandwidths by being specified by a partial bandwidth identifier.

[0203] The first active partial bandwidth may be configured for each of the downlink and the uplink, and may be configured for each of the first active downlink partial bandwidth (first active downlink BWP) and the first active uplink partial bandwidth (first active uplink BWP) by a partial bandwidth indicator. When multiple partial bandwidths are configured for a cell, the first active partial bandwidth may be used to indicate which partial bandwidth is activated first for use. For example, when a PCell, a PSCell, and multiple SCells are configured for a terminal, and multiple partial bandwidths are configured for each of the PCell, the PSCell, or the SCell, if the PCell, the PSCell, or the SCell is activated, the terminal may activate and use the first active partial bandwidth (first active BWP) among the multiple partial bandwidths configured for the PCell, the PSCell, or the SCell. That is, the terminal may activate the first active downlink partial bandwidth (first active downlink BWP) and use it for the downlink, and may activate the first active uplink partial bandwidth (first active uplink BWP) and use it for the uplink.

[0204] When an indication to activate an SCell or activate a partial bandwidth from an inactive state is received via an RRC message, MAC control information, or DCI, an operation can be performed in which, for the SCell, the terminal switches the downlink partial bandwidth to be activated to the first active downlink partial bandwidth, and switches the uplink partial bandwidth to be activated to the first active uplink partial bandwidth. In addition, the operation can be performed when an indication to transfer the SCell or partial bandwidth to an idle state is received via an RRC message, MAC control information, or DCI. This is because, when the SCell or partial bandwidth is activated, the downlink partial bandwidth and the uplink partial bandwidth will be switched to be activated to the first active downlink partial bandwidth and activated to the first active uplink partial bandwidth, respectively, and therefore, only when a channel measurement report is performed in the idle state, the frequency / channel should be measured and reported for the first active downlink / uplink partial bandwidth, and the base station can effectively use the carrier aggregation technology.

[0205] The default partial bandwidth (default BWP) may be configured to be different for each terminal (UE-specific) and may be indicated from a plurality of partial bandwidths by using a partial bandwidth identifier. The default partial bandwidth may be configured only for the downlink. The default partial bandwidth may be used as a partial bandwidth to fall back from an active partial bandwidth in a plurality of downlink partial bandwidths after a specific period of time. For example, a partial bandwidth inactivity timer (BWP inactivity timer) may be configured for each cell or each partial bandwidth via an RRC message, and the timer may be started or restarted when data transmission / reception occurs in an active partial bandwidth instead of the default partial bandwidth, or may be started or restarted when the active partial bandwidth is switched to another partial bandwidth. When the timer expires, the terminal may allow the downlink partial bandwidth activated for the cell to fall back or switch to the default bandwidth. Switching may mean the process of deactivating the currently active partial bandwidth and activating the partial bandwidth to which a switching indication has been provided, and the switching may be triggered by an RRC message, MAC control information (MAC control element) or L1 signaling (downlink control information (DCI) of PDCCH). Switching may be triggered by indicating a partial bandwidth to be switched or activated, and the partial bandwidth may be indicated by a partial bandwidth indicator (eg, 0, 1, 2, 3, or 4).

[0206] The default partial bandwidth is used only for downlink, because the base station allows the terminal to fall back to the basic partial bandwidth of each cell after a certain period of time, and receives an indication from the base station (e.g., DCI of PDCCH), so that the base station scheduling can be facilitated. For example, if the base station configures the default partial bandwidth of a terminal accessing a cell as the initial partial bandwidth, the base station can continuously perform scheduling indications only in the initial partial bandwidth after a specific period of time. In the case where the default partial bandwidth is not configured in the RRC message, the initial partial bandwidth can be considered as the basic partial bandwidth, and the basic partial bandwidth can fall back to the initial partial bandwidth when the partial frequency band inactivity timer expires.

[0207] As another method, in order to enhance the implementation freedom of the base station, a default partial bandwidth may also be defined and configured for the uplink, and may be used as the default partial bandwidth for the downlink.

[0208] In addition, by using the RRCSetup message, RRCResume message (1e-30) or RRCReconfiguration message (1e-45) of the RRC connection configuration, the base station can configure a state transition timer to allow the terminal to autonomously perform a state transition, even though the terminal has not received an indication of an RRC message, MAC control information or DCI of a PDCCH. For example, an inactive timer can be configured for each SCell cell or partial bandwidth, and if the inactive timer expires, the SCell or partial bandwidth can be transferred to an inactive state. In addition, an idle timer can be configured for each SCell or partial bandwidth, and if the idle timer expires, the SCell or partial bandwidth can be transferred to an idle state. When the idle timer expires, only the SCell or partial bandwidth in the active state is transferred to the idle state, and the SCell in the inactive state or idle state is not transferred to the idle state. In addition, an idle state inactive timer can be configured for each SCell or partial bandwidth, and the SCell or partial bandwidth in the idle state can be transferred to the inactive state. When the idle state inactivity timer expires, only the SCell or part of the bandwidth in the idle state is transferred to the inactive state, and the SCell or part of the bandwidth in the active state or the inactive state is not transferred to the inactive state. In the case where the inactivity timer and the idle timer are configured together, the idle timer can be prioritized. That is, in the case where the idle timer is configured, the corresponding SCell or part of the bandwidth will not be deactivated despite the expiration of the inactivity timer. In other words, in the case where the idle timer is configured, when the idle state expires, the SCell or part of the bandwidth is first transferred from the active state to the idle state, and as the idle state inactivity timer expires, the SCell or part of the bandwidth transferred to the idle state is gradually transferred back to the inactive state. Therefore, if the idle timer is configured, the inactivity timer will not affect the state transfer of the SCell or part of the bandwidth, and if the idle timer is configured, the SCell or part of the bandwidth will not be transferred to the inactive state despite the expiration of the inactivity timer.

[0209] In the case where the inactivity timer is not configured for the RRC message, the terminal may consider that the inactivity timer is configured as an infinite value.

[0210] In addition, for the RRCSetup message, RRCResume message (1e-30) or RRCReconfiguration message (1e-45) of the RRC connection configuration, the short-cycle channel measurement report method configuration information can be configured for the partial bandwidth of each cell. For example, a specific partial bandwidth is configured as a partial bandwidth to which the short-cycle channel measurement report method can be applied, and the short-cycle channel measurement report method configuration information can be configured for a specific partial bandwidth. The specific partial bandwidth can be configured as the first active partial bandwidth. This is because the first active partial bandwidth is activated and used when the cell is activated. As another method, the specific partial bandwidth can be indicated as one of multiple partial bandwidths by a partial bandwidth identifier, and can therefore be indicated as a partial bandwidth that is the same as the initial partial bandwidth, the default partial bandwidth, or the first active partial bandwidth. As another method, the short-cycle channel measurement report method configuration information can be configured while being included in the PHY layer or MAC layer configuration information. When activation is indicated to each cell (SCell, PCell or PSCell) configured for the terminal through L1 signaling, MAC CE or RRC, or when partial bandwidth is indicated through L1 signaling, MAC CE or RRC, it is identified whether the short-cycle channel measurement reporting method configuration information is configured for a specific partial bandwidth or the first active partial bandwidth indicated by the RRC message, and the short-cycle channel measurement reporting method can be performed for the partial bandwidth.

[0211] In the present disclosure, the partial bandwidth may indicate an uplink partial bandwidth or a downlink partial bandwidth.

[0212] Figure 1F A view showing a first embodiment is shown, in which, in the next generation mobile communication system of the present disclosure, a terminal is allowed to perform early frequency measurement in an RRC idle mode or an RRC inactive mode and quickly report the frequency measurement result.

[0213] In the first embodiment, when the base station configures frequency measurement configuration information via an RRCRelease message for the terminal, multiple frequency measurement groups can be configured, and the terminal can perform frequency measurement in RRC idle mode or RRC inactive mode, wherein through the frequency measurement configuration information, the terminal will perform frequency measurement in RRC idle mode or RRC inactive mode.

[0214] In addition, the present disclosure proposes that when frequency measurement configuration information is indicated to an RRC inactive mode or RRC idle mode terminal, a separate frequency measurement list or a separate timer is configured according to a frequency configuration group or a radio access technology (or for each cell or for each beam). That is, the present disclosure proposes a method in which a period or timer value indicating how long frequency measurement is to be performed can be configured to provide an indication to the LTE frequency (for each frequency or each cell), and a period or timer value indicating how long frequency measurement will be performed can be configured to provide an indication to the NR frequency (for each frequency, each cell or each beam) separately, so that a separate timer can be configured for each frequency configuration group, and thus a separate period can be configured. That is, a separate timer can be operated for each frequency group, and frequency measurement can be performed until the timer expires. As described above, if a separate timer can be configured for each radio access technology, each cell or each beam, the frequency measurement period can be changed by reflecting the frequency characteristics, beam characteristics or cell characteristics, and thus the battery consumption of the terminal can be advantageously optimized.

[0215] In the first embodiment, the terminal that can perform frequency measurement in the RRC idle mode or the RRC inactive mode and quickly report the frequency measurement result may be a terminal corresponding to one or more of the following situations.

[0216] 1. Any terminal whose capability supports fast frequency measurement and fast frequency measurement result reporting method in RRC idle mode or RRC inactive mode.

[0217] 2. In an RRC idle mode or inactive mode terminal, when a base station switches the terminal from an RRC connected mode to an RRC idle mode or an RRC inactive mode through an RRC message, a terminal that receives configuration information indicating frequency measurement in the RRC idle mode or the RRC inactive mode.

[0218] For example, a terminal for which frequency configuration information for performing frequency measurement in RRC idle mode or RRC inactive mode, a measurement period (e.g., a timer value), or information of an area to perform frequency measurement (e.g., a cell identifier list) has been configured.

[0219] exist Figure 1F In the present invention, a terminal 1f-05 in RRC connected mode can be switched to RRC idle mode or RRC inactive mode (1f-15) by the base station due to a specified reason (for example, because there is no transmission / reception within a specific time period, etc.). When the base station switches the mode of the terminal, an RRC message (1f-10) is sent. For example, an RRCRelease message (an indication of switching to RRC idle mode) or an RRCRelease message including a suspension configuration (an indication of transferring to RRC inactive mode) can be sent.

[0220] When the terminal performs early frequency measurement in the RRC idle mode or the RRC inactive mode, the RRC message may include the following pieces of information or a part thereof.

[0221] - Frequency configuration information to be measured in RRC idle mode or RRC inactive mode.

[0222] ■Frequency configuration information.

[0223] ◆LTE frequency measurement information group or list (EUTRA frequency configuration information / list / group).

[0224] ● It can be configured to include frequency measurement configuration information (early measurement settings), such as which frequencies (e.g., a frequency list) or which frequency bands to measure, where sequential measurements are performed according to the priority configured for each frequency, which filtering method to use to measure the strength of the frequency when measuring the frequency (e.g., L1 filtering, L2 filtering, or L3 filtering method, or which coefficient to use and by which calculation method to perform the measurement), under which event or condition to start the measurement when measuring the frequency, under which criterion (e.g., when the signal strength is equal to or greater than an indicated critical value) to perform the measurement compared with the current serving cell (or the current pre-occupied frequency), under which event or condition to report the measured frequency results, which criterion or condition should be met to report the frequency compared with the current serving cell (or the current pre-occupied frequency), or at which period to report the frequency measurement results.

[0225] ◆NR frequency measurement information group or list (NR frequency configuration information / list / group).

[0226] ● It can be configured to include frequency measurement configuration information (early measurement settings), such as which frequencies (e.g., a frequency list) or which frequency bands to measure, where sequential measurements are performed according to the priority configured for each frequency (or SSB-specific), SSB identifier information or SSB transmission resources (frequency and time resources, beam identifier or beam indicator) for each frequency, which filtering method is used to measure the strength of the frequency when measuring the frequency (e.g., L1 filtering, L2 filtering or L3 filtering method, or which coefficient is used and by which calculation method for measurement), under which event or condition to start measurement when measuring the frequency, under which standard (e.g., when the signal strength is equal to or greater than the indicated critical value) the measurement will be performed compared with the current serving cell (or the current pre-occupied frequency), under which event or condition the measured frequency results will be reported, which standard or condition should be met to report the frequency compared with the current serving cell (or the current pre-occupied frequency), or in which period the frequency measurement results are reported.

[0227] ■The frequency measurement execution period or the frequency measurement execution timer value (e.g., T331) can be configured separately in RRC idle mode or RRC inactive mode, or the timer for LTE frequency and the timer for NR frequency can be configured separately in RRC idle mode or RRC inactive mode. This is because the LTE frequency characteristics (low frequency band) and the NR frequency characteristics (high frequency band) are different from each other, so the frequency measurement time of the terminal can be adjusted separately, which can save the battery of the terminal. For example, in RRCRelease, when frequency measurement is indicated in RRC idle mode or RRC inactive mode, frequency measurement can be performed while the timer is working after startup, and the frequency measurement can be stopped if the timer expires.

[0228] ■Indicates valid area information for performing frequency measurement in RRC idle mode or RRC inactive mode, such as a physical cell identifier (PCID) list. In the case where the terminal is in a cell indicated by the area information, the frequency measurement can be performed, and in the case where the terminal is outside the area information, the frequency measurement can be stopped. For example, in the case where the terminal is outside the area information, the timer can be stopped and the frequency measurement can be stopped. As another method, in the case where the terminal switches to the RRC inactive mode, the base station can use an indicator to determine whether to use the LAN indication area as the valid area. For example, in the case where the base station provides an indication of using the LAN indication area as the valid area to the terminal switched to the RRC inactive mode via an indicator, the terminal can perform frequency measurement in the LAN indication area while maintaining the RRC inactive mode in the LAN indication area. As another method, an indication of using the valid area as the LAN indication area can be provided by an indicator. As another method, in the RRC inactive mode, the terminal can consider and apply the LAN indication area as the valid area even without the indicator, and a separate valid area can be configured for the terminal in the RRC idle mode. In the RRC message, since both the LAN indication area and the validity area are indicated as a list of cell identifiers, the signaling overhead can be reduced by the proposed method. Since the terminal implementation does not require separate management of the validity area, the burden of the terminal implementation can be reduced.

[0229] ■ A measurement reporting threshold can be configured, and multiple frequencies with better signal strength than the threshold in the configured frequency group can be reported.

[0230] In addition, in the RRCRelease message, the second timer value can be defined and configured to indicate how long the frequency measurement result measured by the terminal is valid. For example, when the RRCRelease message is received, the second timer operated by the second timer value can store and use the timer value. The second timer defined above can start when the terminal receives the RRCRelease message, and when the second timer expires, it can be determined that the measured frequency measurement result is invalid, and the result can be discarded. That is, the result will not be reported to the base station. As another method, the second timer defined above can be started when the first timer expires or stops. This is because the frequency measurement result can be continuously updated while performing the frequency measurement, and therefore the validity period of the most recent frequency measurement result can be indicated as the second timer starting as soon as the frequency measurement stops after the first timer expires or stops. In addition, when the second timer expires, it can be determined that the measured frequency measurement result is invalid, and the result can be discarded. That is, the result will not be reported to the base station. As another method, the first timer can be defined alternatively and used to perform the function of the second timer.

[0231] When receiving the RRCRelease message, if the fast frequency measurement configuration information is included, the terminal can cancel or discard the stored frequency measurement configuration information or frequency measurement result, and can perform frequency measurement after saving, updating and applying the new fast frequency measurement configuration information. As another method, if only the frequency measurement period or timer value is set in the fast frequency measurement setting information, the terminal can restart the timer with the value, maintain the existing frequency configuration information, and continue the frequency measurement configuration, or the terminal can start the timer with the value, cancel the existing frequency configuration information, receive system information from the pre-occupied cell via the cell reselection process, and if there is frequency configuration information, perform frequency measurement by applying the frequency configuration information. As another method, a new indicator can be defined for the RRCRelease message to indicate whether to continue or stop the frequency measurement, or whether to cancel the frequency measurement configuration information through the existing frequency measurement configuration information. As another method, the existing frequency configuration information is canceled only when the RRCRelease message has the frequency measurement configuration information, and if there is no frequency configuration information, the existing frequency configuration information can be maintained and applied.

[0232] When the terminal performs fast frequency measurement in the RRC idle mode or the RRC inactive mode, if the condition for starting the frequency measurement satisfies one of the following conditions, the frequency measurement may start (1f-30).

[0233] 1. When the terminal receives the RRCRelease message, when it includes an indicator for providing an indication to perform frequency measurement in RRC idle mode or RRC inactive mode and the frequency information to be measured and the period of measuring the frequency (e.g., a timer value) are configured, the timer can be started and the frequency measurement can be performed according to the frequency information.

[0234] 2. When the terminal receives the RRCRelease message, in the case of including an indicator for providing an indication to perform frequency measurement in RRC idle mode or RRC inactive mode, the period of measuring frequency (e.g., timer value) is configured, and the frequency information to be measured is not included. If the frequency information is sent from the system information, the terminal can first start the timer, and the frequency measurement can be performed according to the frequency information to be measured in the RRC idle mode or RRC inactive mode. If the terminal moves to another cell, in the case where the frequency information to be measured in the RRC idle mode or RRC inactive mode is sent from the system information from the new camped cell, the frequency measurement can be performed according to the new frequency information.

[0235] That is, if the frequency measurement configuration information for performing frequency measurement in RRC idle mode or RRC inactive mode is not configured for the RRCRelease message, then in the case where the terminal sends frequency configuration information for frequency measurement in RRC idle mode or RRC inactive mode from system information, frequency measurement can be performed in RRC idle mode or RRC inactive mode based on this. If the terminal moves and camps on a new cell, the frequency measurement information can be updated with the frequency configuration information for frequency measurement in RRC idle mode or RRC inactive mode, the frequency configuration information is sent to the new cell, and the frequency measurement can be re-performed (1f-12).

[0236] However, if frequency measurement configuration information for performing frequency measurement in RRC idle mode or RRC inactive mode is configured for the RRCRelease message, frequency measurement can be performed while applying the frequency measurement configuration information configured by the RRCRelease message with priority compared to the RRC idle mode or RRC inactive mode frequency measurement information sent from the system information. That is, if frequency measurement configuration information for performing frequency measurement in RRC idle mode or RRC inactive mode is configured for the RRCRelease message, the terminal does not reflect or consider or ignore the frequency configuration information sent from the system information.

[0237] The terminal may start fast frequency measurement (early measurement) according to one or more conditions. The terminal may send message 3 (e.g., RRCSetupRequest or RRCResumeRequest message) to the base station while performing frequency measurement (1f-35), may recognize the success of the random access process by receiving message 4 (e.g., RRCSetup or RRCResume message) from the base station in response thereto (1f-40), and may switch to RRC connection mode (1f-45).

[0238] If an indicator for supporting RRC idle mode or RRC inactive mode frequency measurement or an indicator for providing received RRC idle mode or RRC inactive mode frequency measurement results is sent from system information (e.g., SIB2) received before the terminal configures a connection in the current cell, the terminal can provide the base station with a notification of the frequency measurement results measured in the RRC idle mode or RRC inactive mode through message 5 (e.g., RRCSetupComplete message or RRCResumeComplete message) using the indicator.

[0239] When the terminal sends message 5 (for example, RRC Setup Complete or RRC Resume Complete), the sent message may include an indicator for indicating that frequency measurement (early measurement) has been performed in RRC idle mode or RRC inactive mode, and there are frequency measurement results to be reported. For message 5, a new indicator may be defined to indicate the presence of a fast frequency measurement result, and the indicator (1f-50) used to notify that the terminal information (RRC Setup Complete or RRC Resume Complete) has been defined in the RRC message may be reused. As another method, in the system information, the indicator may define and use an indicator for indicating LTE frequency measurement support or NR frequency measurement support. In addition, when message 5 provides an indication of a frequency measurement result measured in RRC idle mode or RRC inactive mode, an indicator for the measurement result of the LTE frequency and an indicator for the measurement result of the NR frequency may be defined and indicated separately.

[0240] When it is identified in message 5 by an indicator that a fast frequency measurement has been performed in RRC idle mode or RRC inactive mode and there is a measurement result for reporting the measurement, the base station can send a message for requesting a measurement result report to the terminal so as to quickly receive the frequency measurement result report (1f-55). For example, the base station can newly define and use UEinformationRequest as a DL-DCCH message to request frequency measurement result information from the terminal. When receiving the message, the terminal can quickly report the fast frequency measurement result (early measurement) to the base station (1f-65). For example, when receiving the message, the terminal can newly define and use the UEInformationResponse message as a UL-DCCH message to report the frequency measurement result. The frequency measurement result may include a serving cell / frequency measurement result (e.g., NR-SS RSRP / RSRQ), a serving cell / frequency surrounding cell / frequency measurement result, a surrounding cell / frequency measurement result that the terminal can measure, and an indication of a cell / frequency measurement result to be measured, etc. As another method, the base station can define an indicator for the RRCReconfiguration message and use the indicator to request frequency measurement result information from the terminal. When receiving this message, the terminal can quickly report the fast frequency measurement result (early measurement) to the base station (1f-65). For example, when receiving this message, the terminal can report the frequency measurement result by using the RRCReconfigurationComplete message, and can define new fields for reporting frequency measurement results in the UL-DCCH message by another method, and use these fields to perform reporting.

[0241] Regarding the above description, the condition for the terminal to stop fast frequency measurement in the RRC idle mode or inactive mode may be as follows.

[0242] 1. In the case where fast frequency measurement result reporting is supported in the system information of the current cell, after or when an RRC message (eg, message 5) is sent or is about to be sent to the base station to notify that there is a measurement result report.

[0243] 2. When the terminal configures a connection with the network while performing RRC idle mode or RRC inactive mode frequency measurement, and when the terminal receives an RRCSetup message or an RRCResume message through message 4, it stops the timer, stops the measurement, supports fast frequency measurement result reporting in the system information of the current cell, and sends an RRC message (for example, message 5) to the base station to notify the existence of the measurement result report.

[0244] 3. When the measurement report timer (eg, T331) expires.

[0245] 4. In case of leaving the area indicated in RRC idle mode or RRC inactive mode, the frequency measurement area information is configured in the RRCRelease message.

[0246] The terminal may stop RRC idle mode or RRC inactive mode frequency measurement (IDLE mode / / INACTIVE mode measurement) (1f-60) according to one or more of the above conditions.

[0247] The terminal performs measurement on frequencies that the terminal can measure, that is, frequencies supported by the terminal in the fast frequency configuration related information, and at this time, the terminal can select frequencies to be measured by priority according to the specified configuration priority.

[0248] In the present disclosure, a specific terminal operation for reporting frequency measurement results related to the first embodiment is proposed, which is a method for quickly performing and reporting frequency measurement in an RRC idle mode or an RRC inactive mode.

[0249] -When the terminal receives the RRCSetup message or the RRCResume message from the base station through message 4, the terminal can perform the following operations.

[0250] ■If the system information (e.g., SIB2) transmits or includes an indicator (IDLE or INACTIVE Mode Measurement) for indicating support for RRC idle mode or RRC inactive mode frequency measurement, and the terminal has a frequency measurement result measured in the RRC idle mode or RRC inactive mode,

[0251] ◆The terminal configures the RRCSetupComplete message or the RRCResumeComplete message as message 5 to include an indicator (IDLE or INACTIVE Measavailable) in the message, which indicates that there is an RRC idle mode or RRC inactive mode frequency measurement result. Therefore, the message can indicate that there is RRC idle mode or RRC inactive mode frequency measurement information to be reported to the base station.

[0252] ◆ Since the frequency measurement result is to be reported, the timer (eg, T331) for RRC idle mode or RRC inactive mode frequency measurement is stopped. The frequency measurement is stopped, and the frequency measurement configuration information may also be discarded.

[0253] Figure 1H A view showing a second embodiment is shown, in which, in the next generation mobile communication system of the present disclosure, a terminal is allowed to perform early frequency measurement in an RRC idle mode or an RRC inactive mode and quickly report the frequency measurement result.

[0254] In the second embodiment, the description of the first embodiment can be applied. When, for the terminal, the base station configures the frequency measurement configuration information through which the terminal will perform frequency measurement in RRC idle mode or RRC inactive mode via the RRCRelease message, multiple frequency measurement groups can be configured, and the terminal can perform frequency measurement in RRC idle mode or RRC inactive mode. When the terminal configures the connection with the network, the terminal sends message 3 to the base station, and when the base station sends message 4 in response thereto, the base station performs a measurement report indication (e.g., RRCResume) in message 4 and performs a frequency measurement result report (e.g., RRCResumeComplete) in message 5. Therefore, compared with the first embodiment, the frequency measurement result report can be performed quickly, and the measurement results can be reported with enhanced security. This is because the RRC inactive mode terminal activates the security algorithm of SRB1 from the time point of sending message 3. That is, messages 4 and 5 can be encrypted with a new security key in the PDCP entity (PDCP layer) and can be sent while protecting their integrity.

[0255] The terminal may perform frequency measurement in RRC idle mode or RRC inactive mode, store the measurement results, perform random access, and then send message 3 (e.g., RRCSetupRequest message or RRCResumeRequest message). In addition, when the base station sends message 4 (e.g., RRCSetup message or RRCResume message) to the terminal, the base station may provide an indication to the terminal, while including an indicator for indicating the report of the frequency measurement result. As another method, message 4 may represent an indication provided to the terminal regarding reporting the frequency measurement result, so the indicator may be omitted. In addition, the terminal may report the frequency measurement result in message 5 (e.g., RRCSetupComplete message or RRCResumeComplete message). When sending the RRCResumeRequest message, the terminal in RRC inactive mode resumes or activates the security process (encryption and decryption or integrity protection and authentication) for the signaling radio bearer SRB1, and therefore the terminal has the advantage that message 4 can be received with enhanced security, and the frequency measurement result can be reported in message 5 with enhanced security. In addition, by using this information, the base station can send an RRC message while including the carrier aggregation technology configuration or dual connectivity technology configuration information therein, so as to quickly restart, change or newly configure the carrier aggregation technology or dual connectivity technology for the terminal.

[0256] exist Figure 1HIn the embodiment, if the RRC connection mode terminal receives an indication of canceling the RRC connection and switching to the RRC idle mode or the RRC inactive mode and an indication of the frequency measurement configuration information from the base station, the frequency measurement can be performed in the RRC idle mode or the RRC inactive mode within the configured time period or time. However, if the frequency measurement configuration information does not include information about the frequency list to be measured, in the case where the frequency measurement configuration information for measuring the frequency of the RRC idle mode or the RRC inactive mode terminal is sent from the pre-occupied cell while performing the cell reselection process, the information can be received to perform the frequency measurement.

[0257] In addition, when the terminal receives the RRC Release message and switches to the RRC inactive mode, the terminal can perform one of the following methods to effectively process the SCell that has been configured for the carrier aggregation technology and the SCG that has been configured for the dual connectivity technology.

[0258] -Method 1: All configuration information of SCell or configuration information of SCG can be canceled. In addition, when configuring the connection later, the base station can quickly configure the information of SCell for carrier aggregation technology or SCG for dual connection technology for the terminal via RRCReconfiguration message or RRCReconfiguration message based on the fast frequency measurement result report. Method 1 is advantageous in terms of memory because the terminal does not have to maintain the configuration information of SCell or the configuration information of SCG. Method 1 can be easily implemented because the base station does not have to collect the existing configuration information of SCell or SCG from the source base station.

[0259] -Method 2: The configuration information of the SCell or the configuration information of the SCG can be stored, and the transmission or bearer configuration of the SCell or the SCG can be stopped (paused). In addition, when the connection is configured later, the base station can perform recovery for the terminal via the RRCResume message or the RRCReconfiguration message based on the fast frequency measurement result report to reuse the information of the SCell for the carrier aggregation technology or the SCG for the dual connection technology, where only part of the configuration information (incremental configuration) can be updated or the configuration information can be completely new. In method 2, since the terminal maintains the configuration information of the SCell or the configuration information of the SCG, the base station can use the existing configuration information of the SCell or the SCG as is, so the signaling overhead can be reduced, and the terminal can quickly apply and start the carrier aggregation technology or the dual connection technology. Even when the RRC inactive mode terminal resumes the connection, the configuration information of the SCell or the configuration information of the SCG is not canceled or discarded, and the base station defines an indicator in the RRCResume message to indicate whether to maintain or discard the configuration information of the SCell or the configuration information of the SCG. As another method, whether to keep or discard the configuration information of the SCell or the configuration information of the SCG can be indicated by using a complete configuration information indicator (fullConfig). As another method, when the base station sends an RRCRelease message to an RRC connected mode terminal to switch the terminal to an RRC inactive mode, the RRCRelease message can be indicated whether to keep or discard the SCell (MCG or SCG) or SCG configuration information. Therefore, the terminal can keep the configuration information of the SCell or SCG according to the indicator of the RRCRelease message, and even when the RRC connection recovery process starts, the configuration information can be applied according to the indication of the base station (e.g., RRC message). For example, if the RRCRelease message does not include an indication of the SCell or SCG configuration information, the SCell or SCG configuration information is canceled, and if there is an indicator for indicating the retention, storage or discarding of the MCG SCell configuration information or the SCGPSCell or SCell configuration information, the configuration information is stored and maintained according to it, and is applied to the RRC connection recovery process applied according to the indication of the base station (RRC message). The configuration information of the SCell or the configuration information of the SCG may refer to PDCP layer (PDCP entity) configuration information, SDAP layer configuration information, RLC layer configuration information, MAC layer configuration information or PHY layer configuration information, and may indicate part or all of the above information. As another method, since the RRC inactive mode terminal moves while performing the LAN indication area update process, the RRCRelease message received during the LAN indication area update process may be used to indicate whether to maintain or discard the configuration information of the SCell or SCG.This is because, when the LAN indication area update process is performed, the context can be collected and the terminal configuration information can be identified by the identifier. As another method, when the RRC inactive terminal performs the RRC connection recovery process with the base station, the base station responds to the RRCResumeRequest message sent by the terminal for a specified reason (for example, if the terminal context collection fails), and the terminal can discard the configuration information of the SCell or the configuration information of the SCG in the case of indicating the fallback through the RRCSetup message. This is because the base station may not collect the terminal context, so the base station may not identify the configuration information of the SCell or the configuration information of the SCG, which is stored in the terminal. The configuration information of the SCell or the configuration information of the SCG may refer to the PDCP layer (PDCP entity) configuration information, the SDAP layer configuration information, the RLC layer configuration information, the MAC layer configuration information, or the PHY layer configuration information, and may indicate part or all of the above information. When the above method is applied, the base station can quickly configure the carrier aggregation technology or the dual connection technology for the terminal through the RRCResume message or the RRCReconfiguration message during the RRC connection recovery process by using the existing SCell information or SCG information stored in the terminal. When dual connectivity technology is configured, the preamble information, frequency information, etc. required when performing random access to the SCG may be included in the notification to the terminal. In addition, the RRCResume message or the RRCReconfiguration message may indicate the activation of the SCell or SCG, and may indicate fast channel measurement information (short CSI report or non-periodic CSI report) together.

[0260] In addition, when it is necessary to configure an RRC connection with the network, the terminal may indicate the presence of a result of performing frequency measurement in the RRC idle mode or the RRC inactive mode when configuring the connection with the base station.

[0261] When the terminal is to reconfigure the connection with the network in RRC idle mode or RRC inactive mode, in the case where early reporting of frequency measurement results is supported in the cell for which the connection is currently to be configured, the terminal can prepare the frequency measurement results, perform random access, and then send message 3 (e.g., RRCSetupRequest message or RRCResumeRequest message) to the base station (1h-35). In addition, in order to quickly configure the carrier aggregation technology or dual connection technology, the base station can send message 4 (e.g., RRCSetup message or RRCResume message) to the terminal, while including an indicator for indicating the report of the frequency measurement results, and as another method, the indicator can be omitted because the base station sending message 4 can indicate an indication of the report of the frequency measurement results (1h-40). When receiving message 4, the terminal can send and report the frequency measurement results together with message 5 (e.g., RRCSetupComplete message or RRCResumeComplete message) (1h-50). In addition, the connection with the network can be configured, and when the base station sends message 4 (e.g., RRCSetup message or RRCResume message) or RRCReconfiguration message to the terminal, the carrier aggregation technology configuration or dual connectivity technology configuration information can be included therein to quickly restart, change or newly configure the carrier aggregation technology or dual connectivity technology of the terminal. As another method, if multiple frequency configuration information, information about SCell or information about SCG is provided to the RRCResume message, the terminal can select a good frequency or SCG based on the pre-measured frequency result (for example, it can be selected based on the conditions configured by the base station, for example, it can be determined by the signal strength equal to or greater than a certain standard), and the information about the SCell or SCG or the frequency that meets the specified conditions can be reported through RRCResumeComplete. Otherwise, the terminal can directly perform the connection by performing a random access process on the SCell or SCG or frequency that meets the specified conditions. In addition, if the terminal completes the connection with the corresponding cell or base station accessed by the terminal, the base station can provide a notification of terminal access to the source base station. The source base station may have requested connection approval from multiple different target base stations. When the timer is operated and the terminal has no access within a specific period of time, each target base station may determine that the connection has failed, may indicate that the source base station has configured a connection for another target base station, or may directly indicate connection approval cancellation.

[0262] Regarding the above description, the condition for the terminal to stop fast frequency measurement in the RRC idle mode or inactive mode may be as follows.

[0263] 1. In the case where fast frequency measurement result reporting is supported in the system information of the current cell, after or when Message 3 is sent or is to be sent to the base station.

[0264] 2. When the terminal receives an indication of a frequency measurement result report in a random access procedure for configuring a connection with a network when performing RRC idle mode or RRC inactive mode frequency measurement through message 4, and the terminal stops the timer, stops the measurement, supports fast frequency measurement result reporting in the system information of the current cell, and sends an RRC message (e.g., message 5) to the base station to notify the presence of a measurement result report.

[0265] 3. In the case where measurement result reporting is to be performed by Message 5.

[0266] 4. When the measurement report timer (eg, T331) expires.

[0267] 5. In case of leaving the area indicated in the RRC idle mode or RRC inactive mode frequency measurement area information configured in the RRCRelease message.

[0268] The terminal may stop RRC idle mode or RRC inactive mode frequency measurement (IDLE mode / INACTIVE mode measurement) according to one or more of the above conditions.

[0269] The terminal performs measurement on frequencies that the terminal can measure, that is, frequencies supported by the terminal in the fast frequency configuration related information, and at this time, the terminal can select frequencies to be measured by priority according to the specified configuration priority.

[0270] In the present disclosure, the following specific terminal operation for reporting frequency measurement results related to the second embodiment, a method for quickly performing and reporting frequency measurement in RRC idle mode or RRC inactive mode is proposed.

[0271] -When the terminal receives the random access response and message 4 from the base station, the terminal may perform the following operations.

[0272] ■If the system information (e.g., SIB2) transmits or includes an indicator (IDLE or INACTIVE Mode Measurement) for indicating support for RRC idle mode or RRC inactive mode frequency measurement, and the terminal has a frequency measurement result measured in the RRC idle mode or RRC inactive mode,

[0273] ◆The terminal configures message 5 (RRCSetupRequest message or RRCResumeRequest message) to include the RRC idle mode or RRC inactive mode frequency measurement results in the message.

[0274] As another method, the RRC message (eg, message 5) and the frequency measurement result may be sent after being multiplexed in the MAC layer. Therefore, the message may indicate that there is RRC idle mode or RRC inactive mode frequency measurement information to be reported to the base station.

[0275] ◆ Since the frequency measurement result is to be reported, the timer (eg, T331) for RRC idle mode or RRC inactive mode frequency measurement is stopped. The frequency measurement is stopped, and the frequency measurement configuration information and the frequency measurement result may also be discarded.

[0276] The following disclosure proposes a short-cycle-based channel measurement report (short CSI report) method when activating a PCell, SCell, or PSCell by configuring a MAC CE or RRC message, so that the terminal can quickly report the channel measurement for the activated PCell, SCell, or PSCell to the base station within a short period, thereby allowing the base station to quickly allocate transmission resources to the terminal based on this, and data transmission / reception can start quickly. Configuration information for the short-cycle-based channel measurement report method can be provided by the base station via a communication with Figure 1E 1e-30 (RRCSetup message), 1e-45 (RRCReconfiguration message), or 1e-65 (RRCReconfiguration message) in the RRCSetup message and Figure 1H The configuration information can be configured by the same RRC message as 1h-40 (RRCResume message) in the measurement, and the configuration information can be configured to include: a measurement period of the measurement channel; a transmission resource for which the measurement result should be reported (for example, a PUCCH transmission resource, a specific subframe number in which the transmission resource can be reported, etc.); frequency information to be measured; a signal strength threshold value that can be determined by a cell identifier or a valid measurement result (for example, a signal strength greater than the threshold value can be determined as a valid measurement result); a measurement method; or when the time point of executing the RRC message is n (for example, subframe n), the value of X and the value of Y are used to perform frequency channel measurement reports between n+X and n+Y (for example, subframes, TTIs, or symbol units) based on a short period.

[0277] In addition, the present disclosure proposes that the base station can Figure 1E 1e-30 (RRCSetup message), 1e-45 (RRCReconfiguration message), or 1e-65 (RRCReconfiguration message) in the RRCSetup message and Figure 1HThe same RRC message as 1h-40 (RRCrescume message) in 1h-40 (RRCrescume message) is used to directly configure the active, inactive or idle state of the SCell or PSCell. In addition, the present disclosure proposes that the state of the SCell or PSCell can be directly configured as active, inactive or idle via an RRC message or MAC CE, and when the SCell or PSCell receives an indication of the active state through a MAC CE or an RRC message, when a short-cycle-based channel measurement reporting method or configuration is configured for the SCell or PSCell that has been provided with an activation indication, the terminal can report the fast channel measurement results of the SCell or PSCell to the base station based on the short-cycle-based channel measurement reporting method.

[0278] In the case where activation is indicated to the SCell or PSCell by MAC CE, when the time point of receiving the MAC CE is n (for example, subframe, TTI or symbol n), the terminal can quickly report the channel measurement of the SCell or PSCell to the base station within a short period between the (n+A)th and (n+B)th configured for the terminal. In the case where activation is indicated to the SCell or PSCell by an RRC message, when the time point of receiving the RRC message is n (for example, subframe, TTI or symbol n), the terminal can quickly report the channel measurement of the SCell or PSCell to the base station within a short period between the (n+X)th and (n+Y)th configured for the terminal. The value of A or the value of B may be less than the value of X or the value of Y. This is because the processing speed of MAC CE is much faster than the processing and reading speed of RRC messages. The values ​​of A, B, X and Y may be predefined and may be fixed values, and as another method, the base station may be configured to have cell-specific values ​​that are different from each other, as configured by the RRC message. In addition, in order to save the battery of the terminal and prevent power consumption, the terminal stops the short-cycle-based channel measurement reporting method after n+Y or n+B. If a general long-cycle-based channel measurement reporting method is configured, the long-cycle-based channel measurement reporting method (CSI report) may fall back after n+Y or n+B. For example, the value of A and the value of B can be configured to be defined as 8 and 34, respectively, and the value of X and the value of Y can be defined as 20 and 34, respectively.

[0279] Whether to make SCell or PSCell active, idle or inactive can be determined by Figure 1E 1e-30 (RRCSetup message), 1e-45 (RRCReconfiguration message), or 1e-65 (RRCReconfiguration message) in the RRCSetup message and Figure 1H The same RRC message 1h-40 (RRCResume message) is used to indicate.

[0280] The channel measurement report method based on a short cycle can be applied to and used for a PCell or a serving cell. For example, the method can be applied to and used for a handover process, an RRC connection reestablishment process, or an RRC connection recovery process. For example, when the terminal switches from an RRC connection mode to an RRC idle mode or an RRC inactive mode, the base station can send an RRCRelease message or a handover command message to the terminal, and include a channel measurement report method or configuration information based on a short cycle therein, which can be used for a handover process or can be applied to a later RRC connection recovery process. In the case where the terminal receives a handover completion message from the target base station when performing a handover process (or in the case where an indicator is indicated in a random access response), the terminal can quickly report the channel measurement of the serving cell to the target base station by applying a channel measurement report method based on a short cycle. When the terminal performs an RRC connection recovery process, the terminal can quickly report the channel measurement of the serving cell by applying a channel measurement report method based on a short cycle when performing RRCResume. In the RRC connection recovery process, the terminal can send an RRCResumeRequest message to the base station, and then receive an RRCSetup message, an RRCReject message, or an RRCResume message from the base station. The RRCSetup message and the RRCReject message are received from SRB0, and the RRCResume message is always received from SRB1. Therefore, in the case where the short-cycle channel measurement report method or configuration is configured for PCell or serving cell in the RRCRelease message, the value of X and the value of Y can be configured to be smaller, and the terminal can send an RRCResumeRequest message during the RRC connection recovery process to enable fast channel measurement reporting, and then can receive data with a logical channel identifier corresponding to SRB1 from the MAC layer in response thereto, and can immediately report the channel measurement results of the serving cell to the base station quickly based on the short-cycle-based channel measurement configuration information. Therefore, the processing delay of reading the RRCResume message can be reduced. In addition, if the terminal sends an RRCResumeRequest message during the RRC connection recovery process, and then receives a logical channel identifier corresponding to SRB0 from the MAC layer in response thereto, the connection with the serving cell fails, and therefore the short-cycle-based channel measurement configuration information is not performed.

[0281] As another method, the base station can send an RRCRescume message and include a short-cycle-based channel measurement reporting method or configuration information of the serving cell (PCell), SCell or PSCell therein, so that the terminal can process and read the RRCRescume message and report the channel measurement of the serving cell (PCell), SCell or PSCell in a short cycle between n+X and n+Y.

[0282] As another method, in order to apply the non-periodic channel measurement reporting method (non-periodic CSI reporting), the base station can provide the terminal with an indication of the channel measurement of the PCell, SCell or PSCell by using the DCI of the PDCCH, and can provide an indication of the report of the channel measurement through the uplink transmission resources indicated by the DCI of the PDCCH. Therefore, the non-periodic channel measurement reporting method can perform the channel measurement report only once through the allocated uplink transmission resources, and can also perform the triggering after indicating the activation of the PCell, SCell or PSCell through the RRCResume message or the RRCReconfiguration message.

[0283] Only when the RRC message or MAC CE indicates that the PCell, SCell or PSCell is activated, and the short-cycle-based channel measurement reporting method or configuration information is configured for the PCell, SCell or PSCell, the terminal performs short-cycle-based channel measurement reporting.

[0284] In addition, the terminal can Figure 1EThe proposed short-cycle channel measurement reporting method is performed in a specific partial bandwidth configured or indicated for each cell in an RRC message. The specific partial bandwidth in the RRC message is configured as a partial bandwidth to which the short-cycle channel measurement reporting method can be applied, and the short-cycle channel measurement reporting method configuration information can be configured for the specific partial bandwidth. The specific partial bandwidth can be configured as the first active partial bandwidth. This is because the first active partial bandwidth is activated and used when the terminal activates the cell, so applying the short-cycle channel measurement reporting method to the first active partial bandwidth may be effective for fast activation and data transmission / reception. As another method, the specific partial bandwidth can be indicated as one of a plurality of partial bandwidths by a partial bandwidth identifier, and can therefore be indicated as a partial bandwidth that is the same as the initial partial bandwidth, the default partial bandwidth, or the first active partial bandwidth. As another method, the short-cycle channel measurement reporting method configuration information can be configured while being included in the PHY layer or MAC layer configuration information. When activation is indicated to each cell (SCell, PCell or PSCell) configured for the terminal through L1 signaling, MAC CE or RRC, or when partial bandwidth is indicated through L1 signaling, MAC CE or RRC, it is identified whether the short-cycle channel measurement reporting method configuration information is configured for a specific partial bandwidth or the first active partial bandwidth indicated by the RRC message, and the short-cycle channel measurement reporting method can be performed for the partial bandwidth.

[0285] In the present disclosure, the partial bandwidth may indicate an uplink partial bandwidth or a downlink partial bandwidth.

[0286] The following disclosure proposes a first embodiment of a specific terminal operation for performing a short-cycle-based channel measurement report. In the first embodiment, the short-cycle-based channel measurement report method is applied only when the PCell, SCell, or PSCell is activated by the MAC CE. That is, when the PCell, SCell, or PSCell is activated by an RRC message, it is difficult to define the accurate timing of the X value or the Y value due to the delay in the process of reading the RRC message, and therefore the short-cycle-based channel measurement report method is not applied.

[0287] The first embodiment of performing a specific terminal operation of a short-cycle-based channel measurement report in the present disclosure is as follows.

[0288] Each MAC entity of the terminal can perform the following process for PCell, SCell or PSCell at each TTI.

[0289] -If the MAC entity of the terminal is configured to activate PCell, SCell or PSCell through the configuration information of PCell, SCell or PSCell of the RRC message, or if the MAC entity receives a MAC instruction indicating the activation of PCell, SCell or PSCell, the terminal performs the following process according to the timing requirements.

[0290] ■According to the instruction of the RRC message or MAC CE, the PCell, SCell or PSCell is activated. Otherwise, a partial bandwidth of the PCell, SCell or PSCell (a specific partial bandwidth specified by the RRC message or the first active partial bandwidth) is activated.

[0291] If a short-cycle-based channel measurement reporting method (e.g., cqi-shortConfigSCell) is configured for a PCell, SCell, or PSCell to which an activation indication has been provided, and the activation of the PCell, SCell, or PSCell is indicated by a MAC CE (i.e., if the activation of the PCell, SCell, or PSCell is not indicated by an RRC message), or if a short-cycle-based channel measurement reporting method (e.g., cqi-shortConfigSCell) is configured for a partial bandwidth of a PCell, SCell, or PSCell (a specific partial bandwidth specified by an RRC message or a first active partial bandwidth), and the activation of the partial bandwidth of the PCell, SCell, or PSCell (a specific partial bandwidth specified by an RRC message or a first active partial bandwidth) is indicated by a MAC CE (i.e., if the activation of the PCell, SCell, or PSCell (the specific partial bandwidth specified by an RRC message or the first active partial bandwidth) is not indicated by an RRC message),

[0292] ◆The terminal performs a short-cycle based channel measurement reporting method for PCell, SCell or PSCell according to the timing requirements, for example, between n+A and n+B. The channel measurement report may include information such as channel quality indicator (CQI), precoding matrix indicator (PMI), rank indicator (RI) or channel rank indicator (CRI).

[0293] ■In another case (if the short cycle-based channel measurement reporting method (e.g., cqi-shortConfigSCell) is not configured for the PCell, SCell, or PSCell, if the activation of the PCell, SCell, or PSCell is indicated by an RRC message, or if the activation of a partial bandwidth (a specific partial bandwidth specified by an RRC message or a first active partial bandwidth) of the PCell, SCell, or PSCell is indicated by an RRC message),

[0294] ◆Channel measurement reporting can be performed by applying a general long-cycle based channel measurement reporting method (e.g., cqi-ReportConfigSCell), if configured.

[0295] ■ If the PCell, SCell or PSCell or a portion of the bandwidth of the PCell, SCell or PSCell (a specific portion of the bandwidth specified by the RRC message or the first active portion of the bandwidth) is active, and the time for performing the short cycle based measurement reporting method expires or should be stopped according to the timing requirement,

[0296] ◆ Channel measurement reporting can be performed by applying a common long-cycle-based channel measurement reporting method (e.g., cqi-ReportConfigSCell), if configured. That is, the short cycle may fall back to the long cycle to save the terminal's battery.

[0297] The following disclosure proposes a second embodiment of a specific terminal operation for performing a short-cycle-based channel measurement report. In the second embodiment, when the PCell, SCell, or PSCell is activated by a MAC CE and an RRC message, a short-cycle-based channel measurement report method is applied. That is, when the PCell, SCell, or PSCell is activated by an RRC message, taking into account the processing delay of reading the RRC message, a short-cycle-based channel measurement report method is applied between the value of n+X and the value of n+Y, and when the PCell, SCell, or PSCell is activated by a MAC CE, a short-cycle-based channel measurement report method is applied between the value of n+A and the value of n+B.

[0298] A second embodiment of performing a specific terminal operation of a short-cycle-based channel measurement report in the present disclosure is as follows.

[0299] Each MAC entity of the terminal can perform the following process for PCell, SCell or PSCell at each TTI.

[0300] -If the MAC entity of the terminal is configured to activate PCell, SCell or PSCell or partial bandwidth of PCell, SCell or PSCell (specific partial bandwidth specified by RRC message or first active partial bandwidth) through the configuration information of PCell, SCell or PSCell for RRC message, or if the MAC entity receives a MAC CE indicating activation of PCell, SCell, or PSCell or activation of partial bandwidth of PCell, SCell or PSCell (specific partial bandwidth specified by RRC message or first active partial bandwidth), the terminal performs the following process according to the timing requirements.

[0301] ■According to the instruction of the RRC message or MAC CE, activate the PCell, SCell or PSCell or activate part of the bandwidth of the PCell, SCell or PSCell (a specific part of the bandwidth specified by the RRC message or the first active part of the bandwidth).

[0302] ■If the short cycle-based channel measurement reporting method (e.g., cqi-shortConfigSCell) is configured for a PCell, SCell, or PSCell for which an activation indication has been provided, or for a partial bandwidth (a specific partial bandwidth or the first active partial bandwidth specified by an RRC message) of a PCell, SCell, or PSCell,

[0303] ◆The terminal performs a short-cycle-based channel measurement reporting method for PCell, SCell or PSCell or for a portion of the bandwidth of PCell, SCell or PSCell (a specific portion of the bandwidth specified by an RRC message or a first active portion of the bandwidth) according to the timing requirements, for example, between n+A and n+B (when activation is indicated by a MAC CE) or between n+X and n+Y (when activation is indicated by an RRC message). The channel measurement report may include information such as a channel quality indicator (CQI), a precoding matrix indicator (PMI), a rank indicator (RI) or a channel rank indicator (CRI).

[0304] ■ In another case (if the short cycle based channel measurement reporting method (cqi-shortConfigSCell) is not configured for PCell, SCell or PSCell or for a partial bandwidth of PCell, SCell or PSCell (a specific partial bandwidth or the first active partial bandwidth specified by an RRC message),

[0305] ◆Channel measurement reporting can be performed by applying a general long-cycle based channel measurement reporting method (e.g., cqi-ReportConfigSCell), if configured.

[0306] ■ If the PCell, SCell or PSCell, or a portion of the bandwidth of the PCell, SCell or PSCell (a specific portion of the bandwidth or the first active portion of the bandwidth specified by the RRC message) is active, and the time for performing the short cycle based measurement reporting method expires or should be stopped according to the timing requirement,

[0307] ◆ Channel measurement reporting can be performed by applying a common long-cycle-based channel measurement reporting method (e.g., cqi-ReportConfigSCell), if configured. That is, the short cycle may fall back to the long cycle to save the terminal's battery.

[0308] In addition, in the present disclosure, when the terminal switches to the RRC inactive mode, the PCell, SCell or PSCell configuration information that has been configured for the RRC connected mode terminal is stored as terminal context information. When the terminal later starts the RRC connection recovery process to configure the connection with the network, the PCell, SCell or PSCell configuration information can be used for fast service cell activation, fast carrier aggregation technology activation or fast dual connection technology activation without being discarded. When the terminal sends an RRCRelease message for indicating a switch to the RRC inactive mode, the base station can define an indicator for indicating whether the terminal discards or stores each PCell, SCell or PSCell configuration information, and can provide an indication to the terminal. For example, if the RRCRelease message does not have an indicator for the PCell, SCell or PSCell configuration information, the terminal can discard the PCell, SCell or PSCell configuration information when the RRCRelease message is received or when the RRC connection recovery process is performed later. In addition, if the RRCRelease message includes only an indicator for PCell configuration information, only configuration information about the PCell configuration information from the PCell, SCell or PSCell configuration information may be stored, and other configuration information may be discarded when the terminal receives the RRCRelease message or when the RRC connection recovery process is performed later. In addition, if the RRCRelease message includes only an indicator for SCell configuration information, only configuration information about the SCell configuration information from the PCell, SCell or PSCell configuration information may be stored, and other configuration information may be discarded when the terminal receives the RRCRelease message or when the RRC connection recovery process is performed later. In addition, if the RRCRelease message includes only an indicator for MCG configuration information, only configuration information about the MCG (PCell or SCell) configuration information from the PCell, SCell or PSCell configuration information may be stored, and other configuration information may be discarded when the terminal receives the RRCRelease message or when the RRC connection recovery process is performed later. In addition, if the RRCRelease message only includes an indicator for the SCG configuration information, only the configuration information about the SCG (PSCell or SCell) configuration information from the PCell, SCell or PSCell configuration information can be stored, and other configuration information can be discarded when the terminal receives the RRCRelease message or when the RRC connection recovery process is performed later.In addition, if the RRCRelease message includes an indicator for MCG and SCG configuration information, configuration information about MCG (PCell or SCell) and SCG configuration information from PCell, SCell or PSCell configuration information can be stored. When performing the RRC connection recovery process, the stored information indicated by the indicator of the RRCRelease message will not be discarded by the terminal or base station.

[0309] As another method, when RRCRelease is received, the terminal can store all PCell, SCell or PSCell configuration information. Even when the terminal starts the RRC connection recovery process, all information will not be discarded. As proposed in the above-mentioned RRCRelease message, when the terminal performs the RRC connection recovery process and receives the RRCRelease message from the base station, an indicator of each of the PCell, SCell or PSCell configuration information can be defined for the RRCRelease message to determine whether to discard the PCell, SCell or PSCell configuration information and indicate a change in part of the configuration information, and a new indicator (e.g., fullconfig) can be used to discard all existing configuration information and indicate a completely new configuration.

[0310] In addition, in the present disclosure, as described above, when the terminal stores PCell, SCell or PSCell configuration information and uses the configuration information for the RRC connection recovery process, the base station can directly configure the activity state of the SCell or PSCell through the RRCResume message, so that the carrier aggregation technology or dual connection technology can be quickly configured or activated. When the RRCRescume message is received, when the RRCRescume message indicates the activity state of the SCell or PSCell, the terminal can use the short-cycle-based channel measurement reporting method proposed in the present disclosure. In addition, when the RRCResume message is received, the terminal can also apply the short-cycle-based channel measurement reporting method to the serving cell, i.e., the PCell.

[0311] Fig. 1I A diagram showing a terminal operation for performing a frequency measurement report method based on a short cycle proposed by the present disclosure.

[0312] exist Fig. 1I In the embodiment, each MAC entity of the terminal can perform the following process for PCell, SCell or PSCell or for part of the bandwidth of PCell, SCell or PSCell (a specific part of the bandwidth specified by the RRC message or the first active part of the bandwidth) on each TTI.

[0313] If the MAC entity of the terminal is configured to activate PCell, SCell or PSCell or activate partial bandwidth of PCell, SCell or PSCell (specific partial bandwidth specified by RRC message or first active partial bandwidth) through configuration information of PCell, SCell or PSCell for RRC message, or if the MAC entity receives a message indicating PCell, SCell, or PSCell or indicating partial bandwidth of PCell, SCell or PSCell (specific partial bandwidth specified by RRC message or first active partial bandwidth) (1i-05), the terminal performs the following process according to the timing requirements.

[0314] The PCell, SCell or PSCell is activated according to an indication of an RRC message or MAC CE, and if a short-cycle-based channel measurement reporting method (e.g., cqi-shortConfigSCell) is configured for the PCell, SCell or PSCell for which an activation indication has been provided, or for a partial bandwidth (a specific partial bandwidth or a first active partial bandwidth specified by an RRC message) for the PCell, SCell or PSCell (1i-10), the terminal may perform a short-cycle-based channel measurement report for the PCell, SCell or PSCell according to timing requirements, for example, between n+A and n+B (in the case of activation indicated by a MAC CE) or between n+X and n+Y (in the case of activation indicated by an RRC message) (1i-15). The channel measurement report may include information such as a channel quality indicator (CQI), a precoding matrix indicator (PMI), a rank indicator (RI) or a channel rank indicator (CRI).

[0315] In another case (if the short-cycle-based channel measurement reporting method (cqi-shortConfigSCell) is not configured for the PCell, SCell, or PSCell) (1i-10), the channel measurement report (1i-20) can be performed by applying a general long-cycle-based channel measurement reporting method (e.g., cqi-ReportConfigSCell). If the PCell, SCell, or PSCell is active and the time for executing the short-cycle-based measurement reporting method expires or should be stopped according to the timing requirements, the channel measurement report can be performed by applying a general long-cycle-based channel measurement reporting method (e.g., cqi-ReportConfigSCell). That is, the short cycle may fall back to the long cycle to save the battery of the terminal.

[0316] In the present disclosure, the indication of the active, idle or inactive state of a partial bandwidth (a specific partial bandwidth or a first active partial bandwidth specified by an RRC message) of a PCell, SCell or PSCell, or its switching or non-switching to a specific partial bandwidth can be indicated by L1 signaling (DCI of PDCCH).

[0317] Figure 1J The structure of a terminal to which the embodiment is applicable is shown.

[0318] refer to Figure 1J The terminal includes a radio frequency (RF) processor 1j-10, a baseband processor 1j-20, a memory 1j-30 and a controller 1j-40.

[0319] The radio frequency (RF) processor 1j-10 performs functions such as frequency band conversion and amplification of signals for transmitting or receiving signals through a radio channel. That is, the RF processor 1j-10 up-converts the baseband signal provided by the baseband processor 1j-20 into an RF band signal, then transmits the baseband signal through an antenna, and down-converts the RF band signal received through the antenna into a baseband signal. For example, the RF processor 1j-10 may include a transmitting filter, a receiving filter, an amplifier, a mixer, an oscillator, a digital-to-analog converter (DAC), an analog-to-digital converter (ADC), and the like. Figure 1J Only one antenna is shown, but the terminal may include multiple antennas. In addition, the RF processor 1j-10 may include multiple RF chains. In addition, the RF processor 1j-10 can perform beamforming. For beamforming, the RF processor 1j-10 can adjust the phase and size of each signal sent or received through multiple antennas or antenna elements. In addition, the RF processor can perform MIMO operations and receive multiple layers when performing MIMO operations. The RF processor 1j-10 can appropriately configure multiple antennas or antenna elements according to the control of the controller to perform receive beam scanning, or can adjust the direction and beam width of the receive beam so that the receive beam is consistent with the transmit beam.

[0320] The baseband processor 1j-20 performs the conversion function between the baseband signal and the bit stream according to the physical layer standard of the system. For example, when data is transmitted, the baseband processor 1j-20 generates complex symbols by encoding and modulating the transmitted bit stream. In addition, when data is received, the baseband processor 1j-20 recovers the received bit stream by demodulating and decoding the baseband signal provided by the RF processor 1j-10. For example, according to the orthogonal frequency division multiplexing (OFDM) scheme, when data is transmitted, the baseband processor 1j-20 generates complex symbols by encoding and modulating the transmitted bit stream, maps the complex symbols to subcarriers, and then configures OFDM symbols through inverse fast Fourier transform (IFFT) operations and cyclic prefix (CP) insertion. In addition, when data is received, the baseband processor 1j-20 divides the baseband signal provided by the RF processor 1j-10 into OFDM symbol units, recovers the signal mapped to the subcarrier through a fast Fourier transform (FFT) operation, and then recovers the received bit stream through demodulation and decoding.

[0321] As described above, the baseband processor 1j-20 and the RF processor 1j-10 send and receive signals. Therefore, each of the baseband processor 1j-20 and the RF processor 1j-10 can be referred to as a transmitter, a receiver, a transceiver, or a communicator. In addition, at least one of the baseband processor 1j-20 or the RF processor 1j-10 may include a plurality of communication modules so as to support a variety of different radio access technologies with each other. In addition, at least one of the baseband processor 1j-20 and the RF processor 1j-10 may include different communication modules from each other to process signals of different frequency bands from each other. For example, different radio access technologies from each other may include LTE networks, NR networks, and the like. In addition, different frequency bands may include ultra-high frequency (SHF) (e.g., 2.5 GHz and 5 GHz) bands and millimeter (mm) wave (e.g., 60 GHz) bands.

[0322] The memory 1j-30 stores data such as basic programs, application programs, and configuration information for terminal operation. The memory 1j-30 provides the stored data according to a request from the controller 1j-40.

[0323] The controller 1j-40 controls the overall operation of the terminal. For example, the controller 1j-40 sends or receives a signal through the baseband processor 1j-20 and the RF processor 1j-10. In addition, the controller 1j-40 records data to the memory 1j-30 and reads data from the memory 1j-30. To this end, the controller 1j-40 may include at least one processor. For example, the controller 1j-40 may include a communication processor (CP) for performing communication control and an application processor (AP) for controlling a higher layer such as an application.

[0324] Figure 1GA block diagram showing the configuration of a TRP in a radio communication system to which the embodiment is applicable.

[0325] like Figure 1G As shown, the base station is configured to include an RF processor 1g-10, a baseband processor 1g-20, a backhaul transceiver 1g-30, a memory 1g-40, and a controller 1g-50.

[0326] The radio frequency (RF) processor 1g-10 performs functions such as frequency band conversion and amplification of signals for transmitting or receiving signals through a radio channel. That is, the RF processor 1g-10 up-converts a baseband signal provided from the baseband processor 1g-20 into an RF band signal, then transmits the baseband signal through an antenna, and down-converts an RF band signal received through an antenna into a baseband signal. For example, the RF processor 1g-10 may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, and the like. Figure 1G Only one antenna is shown, but the first access node may include multiple antennas. In addition, the RF processor 1g-10 may include multiple RF chains. In addition, the RF processor 1g-10 may perform beamforming. For beamforming, the RF processor 1g-10 may adjust the phase and magnitude of each signal sent or received through multiple antennas or antenna elements. The RF processor may perform downward MIMO operations by transmitting one or more layers.

[0327] The baseband processor 1g-20 performs a conversion function between a baseband signal and a bit stream according to the physical layer standard of the first radio access technology. For example, when data is transmitted, the baseband processor 1g-20 generates complex symbols by encoding and modulating the transmitted bit stream. In addition, when data is received, the baseband processor 1g-20 recovers the received bit stream by demodulating and decoding the baseband signal provided from the RF processor 1g-10. For example, according to the OFDM scheme, when data is transmitted, the baseband processor 1g-20 generates complex symbols by encoding and modulating the transmitted bit stream, maps the complex symbols to subcarriers, and then configures OFDM symbols via IFFT operation and CP insertion. In addition, when data is received, the baseband processor 1g-20 divides the baseband signal provided by the RF processor 1g-10 into OFDM symbol units, recovers the signal mapped to the subcarrier by FFT operation, and then recovers the received bit stream by demodulation and decoding. As described above, the baseband processor 1g-20 and the RF processor 1g-10 send and receive signals. Therefore, each of the baseband processor 1g-20 and the RF processor 1g-10 may be referred to as a transmitter, a receiver, a transceiver, a communicator, or a radio communicator.

[0328] The transceiver 1g-30 provides an interface for performing communications with other nodes in the network.

[0329] The memory 1g-40 stores data such as basic programs, application programs, and configuration information for the operation of the main base station. In particular, the memory 1g-40 can store information about the bearer assigned to the connection terminal, the measurement result reported by the connection terminal, etc. In addition, the memory 1g-40 can store information that is a criterion for determining whether to provide or interrupt multiple connections for the terminal. In addition, the memory 1g-40 provides the stored data according to a request from the controller 1g-50.

[0330] The controller 1g-50 controls the overall operation of the main base station. For example, the controller 1g-50 sends or receives a signal through the baseband processor 1g-20 and the RF processor 1g-10 or through the backhaul transceiver 1g-30. In addition, the controller 1g-50 records data to the memory 1g-40 and reads data from the memory 1g-40. To this end, the controller 1g-50 may include at least one processor.

[0331] Hereinafter, the operating principle of the present disclosure will be described in detail with reference to the accompanying drawings. Here, when describing the present disclosure, in the case where it is determined that the detailed description related to the well-known function or feature may unnecessarily obscure the main idea of ​​the present disclosure, its detailed description will be omitted. In addition, the terms described below are terms defined in consideration of the functions in the present disclosure, and may differ according to the intention, convention, etc. of the user or operator. Therefore, the definition of the terms should be based on the content of the entire specification.

[0332] Hereinafter, when describing the present disclosure, in the case where it is determined that a detailed description related to a well-known function or feature may unnecessarily obscure the main idea of ​​the present disclosure, the detailed description thereof will be omitted. Hereinafter, embodiments will be described in detail with reference to the accompanying drawings.

[0333] For the convenience of description, the terms used in the following description to identify access nodes, terms indicating network entities, terms indicating messages, terms indicating interfaces between network entities, terms indicating various identification information, etc. are exemplified. Therefore, the present disclosure is not limited to the terms to be described below, and other terms indicating objects with equivalent technical meanings may be used.

[0334] In the following, for the convenience of description, the present disclosure uses the terms and names defined in the 3rd Generation Partnership Project Long Term Evolution (3GPP LTE) standard. However, the present disclosure is not limited to the terms and names, and can be equally applied to systems that comply with other standards. In the present disclosure, for the convenience of description, "eNB" can be used in conjunction with "gNB". That is, the base station described by "eNB" can refer to "gNB". In addition, the term "terminal" can refer not only to cellular phones, NB-IoT devices, and sensors, but also to other radio communication devices.

[0335] The present disclosure proposes an efficient reception operation of a PDCP entity (PDCP layer) of a bearer configured for a terminal in a next generation radio communication system, thereby enhancing security and preventing unexpected data loss.

[0336] Figure 2A A diagram showing a structure of an LTE system to which the present disclosure is applicable.

[0337] refer to Figure 2A As shown therein, the radio access network of the LTE system is composed of next generation base stations (evolved Node B, hereinafter referred to as ENB, Node B or base station) 2a-05, 2a-10, 2a-15 or 2a-20, MME 2a-25 and S-GW 2a-30. User terminal 2a-35 accesses the external network through ENB 2a-05 to 2a-20 and S-GW 2a-30.

[0338] exist Figure 2A In the LTE system, ENB 2a-05 to 2a-20 correspond to the existing Node B of the UMTS system. ENB is connected to UE 2a-35 through a radio channel and performs a more complex role than the existing Node B. Since in the LTE system, all user services and real-time services such as VoIP using Internet Protocol are served through a shared channel, a device for performing scheduling by collecting status information such as buffer status, available transmission power status, and channel status of the UE is required, and base stations 2a-05 to 2a-20 are used as the device. One ENB generally controls multiple cells. For example, in order to achieve a transmission speed of 100Mbps, the LTE system uses an orthogonal frequency division multiplexing (OFDM) scheme of, for example, a 20MHz bandwidth as a wireless access technology. In addition, an adaptive modulation and coding (AMC) scheme for determining a modulation scheme and a channel coding rate according to the channel status of the terminal is applied. S-GW2a-30 is a device for providing data bearers, and generates or removes data bearers according to the control of MME 2a-25. MME is a device responsible for various control functions of the terminal and a mobility management function, and is connected to multiple base stations.

[0339] Figure 2B A diagram showing a radio protocol structure in an LTE system to which the present disclosure is applicable is shown.

[0340] refer to Figure 2B In each of the terminal and ENB, the radio protocol of the LTE system includes PDCP 2b-05 or 2b-40, RLC 2b-10 or 2b-35, and MAC 2b-15 or 2b-30. PDCP 2b-05 or 2b-40 is responsible for operations such as IP header compression / restoration. The main functions of PDCP are summarized as follows.

[0341] -Header compression and decompression function (Header compression and decompression: ROHC only).

[0342] -User data transmission function (transmission of user data).

[0343] - In-sequence delivery functionality (in-sequence delivery of higher layer PDUs during PDCP re-establishment of RLC AM).

[0344] - Resequence reordering functionality (split bearer for DC (supports RLC AM only): routing of PDCP PDUs for transmission, reordering of PDCP PDUs for reception).

[0345] - Overlap detection functionality (duplicate detection of lower layer SDUs during PDCP re-establishment of RLC AM).

[0346] - Retransmission functionality (for split bearers for DC, retransmission of PDCP SDUs upon handover, and for RLC AM, retransmission of PDCP PDUs during PDCP data recovery).

[0347] -Encryption and decryption functions.

[0348] - Timer-based SDU removal functionality (timer-based SDU discard in uplink).

[0349] Radio Link Control (RLC) 2b-10 or 2b-35 reconfigures a PDCP Packet Data Unit (PDU) to have an appropriate size, and performs an ARQ operation, etc. The main functions of the RLC are summarized as follows.

[0350] - Data transfer function (transmission of higher layer PDUs).

[0351] -ARQ functionality (error correction via ARQ (applicable only to AM data transmission)).

[0352] - Concatenation, segmentation and reassembly function (concatenation, segmentation and reassembly of RLC SDU (only for UM and AM data transmission)).

[0353] - Re-segmentation function (resegmentation of RLC data PDU (only for AM data transmission)).

[0354] - Resequence reordering function (reordering of RLC data PDUs (only for UM and AM data transmission)).

[0355] - Overlap detection function (duplicate detection (only for UM and AM data transmission)).

[0356] - Error detection function (protocol error detection (AM data transmission only)).

[0357] - RLC SDU removal function (RLC SDU discard (only for UM and AM data transmission)).

[0358] -RLC re-establishment function.

[0359] MAC 2b-15 or 2b-30 is connected to a plurality of RLC entities configured in one terminal and performs operations of multiplexing RLC PDU to MAC PDU and demultiplexing MAC PDU to RLC PDU. The main functions of MAC are summarized as follows.

[0360] - Mapping function (mapping between logical channels and transport channels).

[0361] - Multiplexing and demultiplexing functionality (multiplexing / demultiplexing MAC SDUs belonging to one or more different logical channels into transport blocks transmitted to or from the physical layer on transport channels).

[0362] -Scheduling information reporting function.

[0363] -HARQ functionality (error correction via HARQ).

[0364] - Function to adjust the priority between logical channels (priority handling between logical channels of a UE).

[0365] -Function of adjusting the priority between terminals (processing the priority between UEs through dynamic scheduling).

[0366] -MBMS service identification function.

[0367] -Transmission format selection function (Transmission format selection).

[0368] - Fill function.

[0369] The physical layer 2b-20 or 2b-25 performs operations of performing channel coding and modulation on higher layer data to generate OFDM symbols therefrom and sending the OFDM symbols to a radio channel, or performs demodulation and channel decoding on OFDM symbols received through a radio channel and transmits the demodulated and channel-decoded symbols to a higher layer.

[0370] Figure 2C A diagram showing a structure of a next-generation mobile communication system to which the present disclosure is applicable.

[0371] refer to Figure 2CAs shown therein, the radio access network of the next generation mobile communication system (hereinafter, NR or 5G) is composed of a next generation base station (new radio node B, hereinafter, NR gNB or NR base station) 2c-10 and NR CN 2c-05. The user terminal (new radio user equipment, hereinafter, NR UE or terminal) 2c-15 accesses the external network through the NR gNB 2c-10 and NR CN2c-05.

[0372] exist Figure 2C In the NR gNB 2c-10, the NR gNB 2c-10 corresponds to the eNB of the existing LTE system. The NR gNB is connected to the NR UE 2c-15 through a radio channel and can provide better services than the existing Node B. Since all user services are served through shared channels in the next generation mobile communication system, a device is required to perform scheduling by collecting status information such as buffer status, available transmission power status, and channel status of the UE, and the NR NB 2c-10 acts as the device. One NR gNB generally controls multiple cells. Compared with the current LTE, in order to achieve ultra-high-speed data transmission, the existing maximum bandwidth or larger bandwidth can be included, and beamforming technology can be additionally transplanted by using the orthogonal frequency division multiplexing (OFDM) scheme as the radio access technology. In addition, an adaptive modulation and coding (AMC) scheme for determining the modulation scheme and channel coding rate according to the channel status of the terminal is applied. NR-CN 2c-05 performs functions such as mobility support, bearer configuration, QoS configuration, etc. NR-CN is a device responsible for various control functions of the terminal and mobility management functions, and is connected to multiple base stations. In addition, the next generation mobile communication system can be linked with the existing LTE system, and the NR CN is connected to the MME 2c-25 through a network interface. The MME is connected to the existing base station eNB 2c-30.

[0373] Figure 2D A diagram showing a radio protocol structure of a next-generation mobile communication system to which the present disclosure is applicable is shown.

[0374] refer to Figure 2D , the radio protocol of the next generation mobile communication system includes NRSDAP 2d-01 or 2d-45, NR PDCP 2d-05 or 2d-40, NR RLC 2d-10 or 2d-35 and NR MAC 2d-15 or 2d-30 in each of the terminal and the NR base station.

[0375] The main functions of NR SDAP 2d-01 or 2d-45 may include some of the following functions.

[0376] - User data transfer function (transfer of user plane data).

[0377] - Functionality for mapping uplink and downlink QoS flows and data bearers (mapping between QoS flows and DRBs for DL ​​and UL).

[0378] - Functionality to mark QoS flow ID for uplink and downlink (mark QoS flow ID in DL and UL packets).

[0379] - Functionality for mapping the Reflective QoS flow of uplink SDAP PDU to data bearers (Mapping of Reflective QoS flow of UL SDAP PDU to DRB).

[0380] Regarding the SDAP entity, whether to use the header of the SDAP entity or whether to use the function of the SDAP entity can be configured for the terminal through an RRC message for each PDCP entity (PDCP layer), each bearer or each logical channel, and in the case where the SDAP header is configured, the NAS QoS reflection configuration 1-bit indicator (NAS reflection QoS) and ASQoS reflection configuration 1-bit indicator (AS reflection QoS) of the SDAP header can provide an indication to the terminal so that the terminal can update or reconfigure the mapping information of the data bearer and QoS flow for the uplink and downlink. The SDAP header may include QoS flow ID information indicating QoS. QoS information can be used as data processing priority, scheduling information, etc. to support active services.

[0381] The main functions of NR PDCP 2d-05 or 2d-40 may include part of the following functions.

[0382] -Header compression and decompression function (Header compression and decompression: ROHC only).

[0383] -User data transmission function (transmission of user data).

[0384] - In-sequence delivery function (in-sequence delivery of higher layer PDUs).

[0385] - Out-of-sequence delivery functionality (out-of-order delivery of higher layer PDUs).

[0386] - Resequence reordering function (for reordering of received PDCP PDUs).

[0387] - Overlap detection functionality (duplicate detection of lower layer SDUs).

[0388] -Retransmission function (retransmission of PDCP SDU).

[0389] -Encryption and decryption functions.

[0390] - Timer-based SDU removal functionality (timer-based SDU discard in uplink).

[0391] The sequence reordering function (reordering) for the NR PDCP device refers to the function of reordering the PDCP PDU received from the lower layer based on the PDCP sequence number (SN) order, which may include the function of delivering data to the higher layer in the reordered sequence or the function of directly delivering data without considering the sequence, which may include the function of recording the lost PDCP PDU by reordering the sequence, which may include the function of reporting the status of the lost PDCP PDU to the transmitter side, and which may include the function of requesting retransmission of the lost PDCP PDU.

[0392] The primary functions of NR RLC 2d-10 or 2d-35 may include some of the following functions.

[0393] - Data transfer function (transmission of higher layer PDUs).

[0394] - In-sequence delivery function (in-sequence delivery of higher layer PDUs).

[0395] - Out-of-sequence delivery functionality (out-of-order delivery of higher layer PDUs).

[0396] -ARQ functionality (error correction via ARQ).

[0397] - Concatenation, segmentation and reassembly function (concatenation, segmentation and reassembly of RLC SDU).

[0398] - Re-segmentation function (resegmentation of RLC data PDUs).

[0399] - Resequence reordering function (reordering of RLC data PDUs).

[0400] - Overlap detection function (duplicate detection).

[0401] - Error detection function (protocol error detection).

[0402] - RLC SDU removal function (RLC SDU discard).

[0403] - RLC re-establishment function (RLC Re-establishment).

[0404] The sequential delivery function of the NR RLC device refers to a function of sequentially delivering the RLC SDU received from the lower layer to the higher layer. In the case where the original one RLC SDU is received separately as multiple RLC SDUs, the RLC SDUs are reassembled and delivered. The following functions may be included: a function of rearranging the received RLC PDU based on the RLC sequence number (SN) or the PDCP sequence number (SN), a function of recording the lost RLC PDU by rearranging the sequence, a function of reporting the status of the lost RLC PDU to the transmitter side, and a function of requesting retransmission of the lost RLC PDU;

[0405] And it may include a function of sequentially transmitting to a higher layer only the RLC SDUs preceding the lost RLC SDUs in the presence of lost RLC SDUs, a function of sequentially transmitting to a higher layer all RLC SDUs received before the start of the timer despite the presence of lost RLC SDUs if a specified timer expires, or a function of sequentially transmitting to a higher layer all RLC SDUs that have been received until the current time despite the presence of lost RLC SDUs if a specified timer expires. In addition, the RLC PDUs may be processed in the order in which the RLC PDUs are received (in the order of arrival, regardless of the order of sequence numbers) and may be transmitted to the PDCP device regardless of the order (out-of-order transmission). In the case of segmentation, segments stored in a buffer or to be received later may be received, reconstructed into a complete RLC PDU, processed and transmitted to the PDCP device. The NR RLC layer may not include a cascading function. This function may be performed in the NR MAC layer, or may be replaced by a multiplexing function of the NR MAC layer.

[0406] The non-sequential delivery function (out-of-order delivery) of the NR RLC device refers to a function of directly delivering the RLC SDU received from a lower layer to a higher layer without considering the sequence, and may include a function of reassembling and transmitting the RLC SDU when the original one RLC SDU is received separately as multiple RLC SDUs, and may include a function of storing the RLC SN or PDCP SN of the received RLC PDU and arranging a sequence to record the lost RLC PDU.

[0407] NR MAC 2d-15 or 2d-30 can be connected to multiple NR RLC entities configured in one terminal, and the main functions of NR MAC may include part of the following functions.

[0408] - Mapping function (mapping between logical channels and transport channels).

[0409] -Multiplexing and demultiplexing functions (multiplexing / demultiplexing of MAC SDU).

[0410] -Scheduling information reporting function.

[0411] -HARQ functionality (error correction via HARQ).

[0412] - Function to adjust the priority between logical channels (priority handling between logical channels of a UE).

[0413] -Function of adjusting the priority between terminals (processing the priority between UEs through dynamic scheduling).

[0414] -MBMS service identification function.

[0415] -Transmission format selection function (Transmission format selection).

[0416] - Fill function.

[0417] The NR PHY layer 2d-20 or 2d-25 performs an operation of performing channel coding and modulation on higher layer data to generate OFDM symbols therefrom and sending the OFDM symbols to a radio channel, or performs demodulation and channel decoding on OFDM symbols received through a radio channel and transmits the demodulated and channel-decoded symbols to a higher layer.

[0418] Figure 2E A view is shown explaining a process in which a base station releases a connection of a terminal so that the terminal switches from an RRC connected mode to an RRC idle mode and a process in which a terminal configures a connection with a base station so as to switch from an RRC idle mode to an RRC connected mode in the present disclosure.

[0419] exist Figure 2E In the RRC connection mode, if a terminal that sends or receives data does not send or receive data due to a specified reason or within a certain period of time, the base station sends an RRCConnectionRelease message to the terminal to convert the terminal to RRC idle mode (2e-01). If data to be sent appears later, the terminal that is not currently configured with a connection (hereinafter referred to as an idle mode UE) can perform an RRC connection establishment process with the base station. Through the random access process, the terminal can establish reverse transmission synchronization with the base station and send an RRCConnectionRelease message to the base station (2e-05). The message includes the reason (establishmentCause) for configuring the connection with the terminal identifier, etc. The base station can send an RRCConnectionSetup message to allow the terminal to configure the RRC connection (2e-10).

[0420] The RRCConnectionSetup message may include RRC connection configuration information, etc. In addition, the RRCConnectionSetup message may include bearer configuration information of the terminal, configuration information of the PHY layer, configuration information of the MAC layer, configuration information of the RLC layer, configuration information of the PDCP layer (PDCP entity), or configuration information of the SDAP layer, and the configuration information of the PDCP entity (PDCP layer) may include an indicator for providing an indication of whether to use integrity protection or authentication function to each bearer, each PDCP entity (PDCP layer), SRB, or DRB, so as to enhance security.

[0421] The RRC connection is also called a signaling radio bearer (SRB), and is used for sending / receiving RRC messages as control messages between the terminal and the base station. The terminal for which the RRC connection has been configured can send an RRCConnectionSetupComplete message to the base station (2e-15). The message may include a control message (e.g., SERVICEREQUEST), through which the terminal requests the bearer configuration of the specified service from the MME. The base station sends the SERVICE REQUEST message stored in the RRCConnectionSetupComplete message to the MME (2e-20), and the MME determines whether to provide the service requested by the terminal.

[0422] As a result of the determination, if it is determined that the service requested by the terminal is provided, the MME may send an INITIALCONTEXT SETUP REQUEST message to the base station (2e-25). The message includes information such as quality of service (QoS) information to be applied when configuring a data radio bearer (DRB) and security-related information (e.g., security keys or security algorithms) to be applied to the DRB.

[0423] In order to configure security with the terminal, the base station exchanges SecurityModeCommand messages (2e-30) and SecurityModeComplete messages (2e-35). If the security configuration is completed, the base station may send an RRCConnectionReconfiguration message (2e-40) to the terminal.

[0424] In addition, the RRCConnectionReconfiguration message may include bearer configuration information of the terminal, configuration information of the PHY layer, configuration information of the MAC layer, configuration information of the RLC layer, configuration information of the PDCP layer (PDCP entity) or configuration information of the SDAP layer, and the configuration information of the PDCP entity (PDCP layer) may include an indicator for providing an indication of whether to use integrity protection or authentication function to each bearer, each PDCP entity (PDCP layer), SRB or DRB, so as to enhance security.

[0425] The configuration information of the DRB where user data will be processed is included in the message, and the terminal configures the DRB by applying the information and sends an RRCConnectionReconfigurationComplete message to the base station (2e-45). The base station that has completed the DRB configuration with the terminal sends an INITIAL CONTEXT SETUP COMPLETE message to the MME (2e-50), and the MME that has received the message can exchange an S1 BEARER SETUP message and an S1 BEARER SETUPRESPONSE message to configure the S-GW and the S1 bearer (2e-055 and 2e-60). The S1 bearer is a connection for data transmission, as configured between the S-GW and the base station, and can correspond one-to-one to the DRB.

[0426] Once the above process is fully completed, the terminal can send data to the base station or receive data from the base station through the S-GW (2e-65 and 2e-70). The general data transmission process includes three main steps, such as RRC connection configuration, security configuration, and DRB configuration. In addition, in order to update, add or change the configuration of the terminal for a specified reason, the base station can send an RRCConnectionReconfiguration message (2e-75).

[0427] In the present disclosure, a bearer may mean an SRB and a DRB, wherein an SRB may mean a signaling radio bearer, and a DRB may mean a data radio bearer. SRBs are generally used to send and receive RRC messages of an RRC layer, and DRBs are generally used to send and receive user layer data. In addition, a UM DRB refers to a DRB that operates in an unacknowledged mode (UM) using an RLC layer, and an AMDRB refers to a DRB that operates in an acknowledged mode (AM) using an RLC layer.

[0428] The present disclosure proposes a method for processing data at a receiver end to prevent attacks that cause data loss due to abuse of integrity protection or authentication procedures and data overlap detection methods when data is transmitted or received between a terminal and a base station.

[0429] The above-mentioned attack resulting in data loss can be performed by abusing the receiving operation of the PDCP entity (PDCP layer).

[0430] As described above, a first embodiment of the operation of the receiving PDCP entity (PDCP layer) of an SRB or DRB that may be abused is as follows.

[0431] When the received data is processed, the receiving PDCP entity (PDCP layer) may maintain and manage three COUNT variables. When the received data is processed, the receiving PDCP entity (PDCP layer) uses a second COUNT variable to maintain a COUNT value of the data (e.g., PDCP SDU) expected to be received next, and the second COUNT variable may be named RX_NEXT. In addition, when the received data is processed, the receiving PDCP entity (PDCP layer) uses a third COUNT variable to maintain a COUNT value of the first data (e.g., PDCP SDU) that has not been transmitted to a higher layer, and the third COUNT variable may be named RX_DELIV. In addition, when the received data is processed, the receiving PDCP entity (PDCP layer) uses a fourth COUNT variable to maintain a COUNT value of the data (e.g., PDCP SDU) that has triggered a PDCP reordering timer (t-Reording), and the fourth COUNT variable may be named RX_REORD. In addition, when the received data is processed, the receiving PDCP entity (PDCP layer) uses the fifth COUNT variable to maintain the COUNT value of the currently received data (eg, PDCP SDU), and the fifth COUNT variable may be named RCVD_COUNT. Figure 1E As shown, the PDCP reordering timer uses a timer value or part thereof configured by an RRC message in a higher layer (RRC layer), and the timer is used to detect lost PDCP PDUs. Only one timer runs at a time.

[0432] In addition, in the operation of receiving the PDCP entity (PDCP layer), the terminal can define and use the following variables.

[0433] -HFN: refers to the hyperframe number (HFN) portion of the window state variable.

[0434] -SN: refers to the sequence number (SN) portion of the window state variable.

[0435] -RCVD_SN: PDCP sequence number contained in the received PDCP PDU header.

[0436] -RCVD_HFN: HFN value of the received PDCP PDU calculated by the receiving PDCP entity (PDCP layer).

[0437] The operation of the receiving PDCP entity (PDCP layer) of the terminal or base station proposed by the present disclosure is as follows.

[0438] When receiving a PDCP PDU from a lower layer, the receiving PDCP entity (PDCP layer) may determine the COUNT value of the received PDCP PDU as follows.

[0439] - If the received RCVD_SN satisfies RCVD_SN <= SN(RX_DELIV) - Window_Size,

[0440] ■ Update to RCVD_HFN = HFN(RX_DELIV) + 1.

[0441] - Otherwise, if RCVD_SN satisfies RCVD_SN > SN(RX_DELIV) + Window_Size,

[0442] ■ Update to RCVD_HFN = HFN(RX_DELIV) - 1.

[0443] - In another case,

[0444] ■ Update to RCVD_HFN = HFN(RX_DELIV).

[0445] - RCVD_COUNT is determined as RCVD_COUNT = [RCVD_HFN, RCVD_SN].

[0446] After determining the COUNT value of the received PDCP PDU, the receiving PDCP entity (PDCP layer) updates the window status variable and processes the PDCP PDU as follows.

[0447] - Using the RCVD_COUNT value, for the PDCP PDU, perform decryption and perform integrity verification.

[0448] ■ If the integrity verification fails,

[0449] ■ Indicate to the higher layer that the integrity verification fails, and discard the received PDCP data PDU unit (the data part of the PDCP PDU).

[0450] - If RCVD_COUNT < RX_DELIV is satisfied, or if a PDCP PDU with the RCVD_COUNT value has been received previously (in the case of packets that are about to expire, out of cycle, or out of window, or overlapping packets),

[0451] ■ The received PDCP data PDU (the data part of the PDCP PDU) is discarded.

[0452] If the received PDCP PDU is not discarded, the receiving PDCP entity (PDCP layer) operates as follows.

[0453] - The processed PDCP SDU is stored in the receive buffer.

[0454] -If RCVD_COUNT>=RX_NEXT,

[0455] ■RX_NEXT is updated to RCVD_COUNT+1.

[0456] - if an out-of-order delivery indicator (outOfOrderDelivery) has been configured (if an out-of-order delivery operation is indicated),

[0457] ■PDCP SDU is delivered to higher layers.

[0458] - If RCVD_COUNT is the same as RX_DELIV,

[0459] ■Data is transmitted to higher layers in the order of COUNT values.

[0460] ◆ Starting from the value of COUNT = RX_DELIV, all consecutive PDCP SDUs are delivered to higher layers.

[0461] ■ The RX_DELIV value is updated to the COUNT value of the first PDCP SDU which is equal to or greater than RX_DELIV and has not yet been delivered to higher layers.

[0462] - If the t-Reordering timer is running and the RX_DELIV value is equal to or greater than RX_REORD,

[0463] ■t-Reordering timer is stopped and reset.

[0464] - If the t-Reordering timer is not being operated (including when stopped under the above conditions) and RX_DELIV is less than RX_NEXT,

[0465] ■RX_REORD value is updated to RX_NEXT.

[0466] ■t-Reordering timer starts.

[0467] When the PDCP reordering timer (t-Reordering) expires, the receiving PDCP entity (PDCP layer) may operate as follows.

[0468] - If the header decompression process has not been applied before (that is, if data processing has not been performed on the higher layer header), the header decompression process is performed on the stored data, and the data is transmitted to the higher layer in the order of COUNT values.

[0469] ■All PDCP SDUs with COUNT values ​​less than the RX_REORD value have been transmitted.

[0470] ■ Starting from the RX_REORD value, all PDCP SDUs with consecutive COUNT values ​​have been transmitted.

[0471] - The RX_DELIV value is updated to the COUNT value of the first PDCP SDU that is equal to or greater than RX_REORD and has not yet been delivered to higher layers.

[0472] - If the RX_DELIV value is less than the RX_NEXT value,

[0473] ■RX_REORD value is updated to RX_NEXT value.

[0474] ■t-Reordering timer starts.

[0475] In a first embodiment of the operation of receiving a PDCP entity (PDCP layer), an integrity protection or authentication process may be configured for an SRB or a DRB. If an integrity verification (or integrity authentication) failure of received data occurs, even when an integrity protection or authentication process is configured for an SRB, the integrity verification failure may be reported to a higher layer (e.g., an RRC layer (or an RRC entity)), and the higher layer entity may trigger an RRC connection reestablishment process. That is, since the connection of the terminal is reconfigured, the bearer may be canceled and reconfigured. It is used to regard the occurrence of an integrity failure as an attack and to avoid the attack by newly configuring an RRC connection because important messages such as RRC messages for sending or receiving configurations between the terminal and the base station are sent and received.

[0476] However, in the case where integrity protection or authentication procedures are configured for DRB, if the integrity verification procedure of the received data fails, the receiving PDCP entity (PDCP layer) may report the integrity verification failure to a higher layer and discard the data in which the integrity verification failure has occurred, but data transmission / reception may still be performed. Here, attention should be paid to the overlap detection procedure performed after the integrity verification procedure.

[0477] In a first embodiment of the operation of a receiving PDCP entity (PDCP layer) of the present disclosure, when data corresponding to a COUNT value is received, the receiving PDCP entity (PDCP layer) may perform an integrity verification process through the COUNT value and discard the data in which failure has occurred, and in an overlap detection process, if a COUNT value corresponding to the currently received data has been received, that is, if data corresponding to the COUNT value has been received, the receiving PDCP entity (PDCP layer) may discard the data.

[0478] Therefore, due to abusing the first embodiment of the operation of the receiving PDCP entity (PDCP layer) or exploiting its shortcomings, a data usage attack may occur.

[0479] Figure 2F A diagram illustrating security issues that may occur in a first embodiment of operations of a receiving PDCP entity (PDCP layer) of an SRB or DRB of the present disclosure is shown.

[0480] refer to Figure 2F Due to an external attack, many data with different COUNT values ​​from each other may be sent to the receiving PDCP entity (PDCP layer) (2f-05). Then, in the case where integrity protection or authentication procedures are configured, the receiving PDCP entity (PDCP layer) can identify the integrity verification failure of the sent data and discard the data corresponding to the attack (2f-10).

[0481] However, the problem is that the PDCP entity (PDCP layer) believes that the COUNT value corresponding to the data caused by the attack has been received. Therefore, although normal data sent from the transmitting end is received instead of the attack data, if the COUNT value corresponding to the normal data is the same as the COUNT value of the attack data (2f-15), the receiving PDCP entity (PDCP layer) regards the normal data as overlapped reception through the overlap detection process and discards the normal data (2f-20). Therefore, the receiving PDCP entity (PDCP layer) discards the normal data through the overlap detection process, so data loss may occur.

[0482] Therefore, the present disclosure proposes the following embodiments of a receiving PDCP entity (PDCP layer) to prevent attacks that cause data loss due to abuse of the integrity protection or authentication process and overlap detection process as described above.

[0483] Figure 2G A diagram showing an embodiment of an efficient PDCP entity (PDCP layer) for SRB or DRB proposed by the present disclosure is shown.

[0484] In an embodiment of the receiving PDCP entity (PDCP layer) proposed in the present disclosure, during the overlap detection process, when a COUNT value corresponding to the currently received data has been previously received, and data corresponding to the COUNT value has been successfully received previously, rather than just simply received, the receiving PDCP entity (PDCP layer) can determine that overlap detection has occurred, and can discard the received data to enhance the overlap detection process and prevent external attacks.

[0485] For example, multiple data with different COUNT values ​​from each other may be sent to the receiving PDCP entity (PDCP layer) (2g-05). In the case where integrity protection or authentication procedures are configured, the receiving PDCP entity (PDCP layer) may recognize that the integrity verification of the transmitted data has failed and discard the data corresponding to the attack (2g-10). In addition, since the attack data has not been successfully received, the receiving PDCP entity (PDCP layer) may consider that the COUNT value corresponding to the data has never been received.

[0486] Therefore, in the case of receiving normal data sent from the transmitting end instead of attacking data, although the COUNT value corresponding to the normal data is the same as the COUNT value of the attacking data (2g-15), the receiving PDCP entity (PDCP layer) may not regard the normal data as overlapping reception through the overlap detection process, and may not discard the normal data. Therefore, the receiving PDCP entity (PDCP layer) may perform data processing of the PDCP entity (PDCP layer), such as decryption, integrity verification, or header decompression, on the normal data, and may then sequentially transmit the data to a higher layer (sG-20). Therefore, the security issue of the receiving PDCP entity (PDCP layer) discarding normal data through the overlap detection process may be resolved.

[0487] The present disclosure proposes the following second embodiment of the receiving PDCP entity (PDCP layer) for SRB or DRB to prevent attacks that cause data loss due to the abuse of the integrity protection or authentication process and the overlap detection process as described above. Specifically, in the overlap detection process, if the COUNT value corresponding to the currently received data has been previously received, and the data corresponding to the COUNT value has been successfully received before, rather than simply received, the receiving PDCP entity (PDCP layer) can determine that overlap detection has occurred, and the received data can be discarded to enhance the overlap detection process and prevent external attacks. The successful reception of data can indicate: the data corresponding to the COUNT value has been processed and stored in the buffer; the data has been received, processed and transmitted to a higher layer; the data has been transmitted to a higher layer (higher layer entity) and has been discarded; or in the case where the integrity protection or authentication process is configured, the integrity verification has been successfully performed on the data corresponding to the COUNT value. That is, it can be determined that the integrity verification failure of the received data caused by the external attack has not been successfully received by the data, so that normal data can be prevented from being discarded in the overlap detection process. The specific process of the second embodiment of the receiving PDCP entity (PDCP layer) proposed in the present disclosure is as follows.

[0488] When receiving a PDCP PDU from a lower layer, the receiving PDCP entity (PDCP layer) may determine the COUNT value of the received PDCP PDU as follows.

[0489] - If the received RCVD_SN satisfies RCVD_SN<=SN(RX_DELIV)-Window_Size,

[0490] ■Updated to RCVD_HFN=HFN(RX_DELIV)+1.

[0491] - Otherwise, if RCVD_SN satisfies RCVD_SN>SN(RX_DELIV)+Window_Size,

[0492] ■Updated to RCVD_HFN=HFN(RX_DELIV)-1.

[0493] - In another case,

[0494] ■Updated to RCVD_HFN=HFN(RX_DELIV).

[0495] -RCVD_COUNT is determined as RCVD_COUNT = [RCVD_HFN, RCVD_SN].

[0496] After determining the COUNT value of the received PDCP PDU, the receiving PDCP entity (PDCP layer) updates the window status variable and processes the PDCP PDU as follows.

[0497] - Using the RCVD_COUNT value, for the PDCP PDU, perform decryption and perform integrity verification.

[0498] ■ If the integrity verification fails,

[0499] ◆ Indicate to the higher layer that the integrity verification has failed, and discard the received PDCP data PDU (the data part of the PDCP PDU).

[0500] - If RCVD_COUNT < RX_DELIV is satisfied or

[0501] - If a PDCP PDU with the value of RCVD_COUNT has been successfully received previously,

[0502] ■ The received PDCP data PDU (the data part of the PDCP PDU) is discarded.

[0503] If the received PDCP PDU is not discarded, the receiving PDCP entity (PDCP layer) operates as follows.

[0504] - The processed PDCP SDU is stored in the receive buffer.

[0505] - If RCVD_COUNT >= RX_NEXT is satisfied,

[0506] ■ RX_NEXT is updated to RCVD_COUNT + 1.

[0507] - If the out-of-order delivery indicator (outOfOrderDelivery) has been configured (if out-of-order delivery operation is indicated),

[0508] ■ The PDCP SDU is delivered to the higher layer.

[0509] - If RCVD_COUNT is the same as RX_DELIV,

[0510] ■ The data is delivered to the higher layer in the order of the COUNT value.

[0511] ◆ Starting from the value of COUNT = RX_DELIV, all consecutive PDCP SDUs are delivered to the higher layer.

[0512] ■ The RX_DELIV value is updated to the COUNT value of the first PDCP SDU which is equal to or greater than RX_DELIV and has not yet been delivered to higher layers.

[0513] - If the t-Reordering timer is running and the RX_DELIV value is equal to or greater than RX_REORD,

[0514] ■t-Reordering timer is stopped and reset.

[0515] - If the t-Reordering timer is not being operated (including when stopped under the above conditions) and RX_DELIV is less than RX_NEXT,

[0516] ■RX_REORD value is updated to RX_NEXT.

[0517] ■t-Reordering timer starts.

[0518] When the PDCP reordering timer (t-Reordering) expires, the receiving PDCP entity (PDCP layer) may operate as follows.

[0519] - If the header decompression process has not been applied before (that is, if data processing has not been performed on the higher layer header), the header decompression process is performed on the stored data segments, and the data is transmitted to the higher layer in the order of COUNT values.

[0520] ■All PDCP SDUs with COUNT values ​​less than the RX_REORD value have been transmitted.

[0521] ■ Starting from the RX_REORD value, all PDCP SDUs with consecutive COUNT values ​​have been transmitted

[0522] - The RX_DELIV value is updated to the COUNT value of the first PDCP SDU that is equal to or greater than RX_REORD and has not yet been delivered to higher layers.

[0523] - If RX_DELIV is less than RX_NEXT,

[0524] ■RX_REORD value is updated to RX_NEXT value.

[0525] ■t-Reordering timer starts.

[0526] In addition, the present disclosure proposes the following third embodiment of a receiving PDCP entity (PDCP layer) for SRB or DRB to prevent attacks that cause data loss due to abuse of the integrity protection or authentication process and overlap detection process as described above.

[0527] Specifically, during the overlap detection process, if a COUNT value corresponding to the currently received data has been previously received, and data corresponding to the COUNT value has been previously successfully received (in the case where integrity protection or authentication process is configured, if data corresponding to the COUNT value has been previously received and the integrity verification process has been successfully performed), the receiving PDCP entity (PDCP layer) can determine that overlap detection has occurred, and can discard the received data to enhance the overlap detection process and prevent external attacks.

[0528] The successful reception of data may indicate: the data corresponding to the COUNT value has been processed and stored in the buffer; the data has been received, processed and transmitted to a higher layer; the data has been transmitted to a higher layer and has been discarded; or, in the case where integrity protection or authentication procedures are configured, integrity verification has been successfully performed on the data corresponding to the COUNT value. That is, it can be determined that the integrity verification failure of the received data due to an external attack has not been successfully received by the data, so that normal data can be prevented from being discarded during the overlap detection process. The specific process of the third embodiment of the receiving PDCP entity (PDCP layer) proposed in the present disclosure is as follows.

[0529] When receiving a PDCP PDU from a lower layer, the receiving PDCP entity (PDCP layer) may determine the COUNT value of the received PDCP PDU as follows.

[0530] - If the received RCVD_SN satisfies RCVD_SN<=SN(RX_DELIV)-Window_Size,

[0531] ■Updated to RCVD_HFN=HFN(RX_DELIV)+1.

[0532] - Otherwise, if RCVD_SN satisfies RCVD_SN>SN(RX_DELIV)+Window_Size,

[0533] ■Updated to RCVD_HFN=HFN(RX_DELIV)-1.

[0534] - In another case,

[0535] ■Updated to RCVD_HFN=HFN(RX_DELIV).

[0536] - The RCVD_COUNT is determined as RCVD_COUNT = [RCVD_HFN, RCVD_SN].

[0537] After determining the COUNT value of the received PDCP PDU, the receiving PDCP entity (PDCP layer) updates the window status variable and processes the PDCP PDU as follows.

[0538] - Using the RCVD_COUNT value, for the PDCP PDU, decryption is performed and integrity verification is carried out.

[0539] ■ If the integrity verification fails,

[0540] ◆ Indicate to the higher layer that the integrity verification has failed, and discard the received PDCP data PDU (the data part of the PDCP PDU).

[0541] - If RCVD_COUNT < RX_DELIV or

[0542] - If a PDCP PDU with the RCVD_COUNT value has been successfully received previously, and if the integrity verification process corresponding to the PDCP PDU with the RCVD_COUNT value has been successfully executed previously in the case where integrity protection or authentication process is configured,

[0543] ■ The received PDCP data PDU (the data part of the PDCP PDU) is discarded.

[0544] If the received PDCP PDU is not discarded, the receiving PDCP entity (PDCP layer) operates as follows.

[0545] - The processed PDCP SDU is stored in the receive buffer.

[0546] - If RCVD_COUNT >= RX_NEXT,

[0547] ■ RX_NEXT is updated to RCVD_COUNT + 1.

[0548] - If the out-of-order delivery indicator has been configured (if out-of-order delivery operation is indicated),

[0549] ■ The PDCP SDU is delivered to the higher layer.

[0550] - If RCVD_COUNT is the same as RX_DELIV,

[0551] ■ The data is delivered to the higher layer in the order of the COUNT value.

[0552] ◆ Starting from the value of COUNT = RX_DELIV, all consecutive PDCP SDUs are delivered to higher layers.

[0553] ■ The RX_DELIV value is updated to the COUNT value of the first PDCP SDU which is equal to or greater than RX_DELIV and has not yet been delivered to higher layers.

[0554] - If the t-Reordering timer is running and the RX_DELIV value is equal to or greater than RX_REORD,

[0555] ■t-Reordering timer is stopped and reset.

[0556] - If the t-Reordering timer is not being operated (including when stopped under the above conditions) and RX_DELIV is less than RX_NEXT,

[0557] ■RX_REORD value is updated to RX_NEXT.

[0558] ■t-Reordering timer starts.

[0559] When the PDCP reordering timer (t-Reordering) expires, the receiving PDCP entity (PDCP layer) may operate as follows.

[0560] - If the header decompression process has not been applied before (that is, if data processing has not been performed on the higher layer header), the header decompression process is performed on the stored data, and the data is transmitted to the higher layer in the order of COUNT values.

[0561] ■All PDCP SDUs with COUNT values ​​less than the RX_REORD value have been transmitted.

[0562] ■ Starting from the RX_REORD value, all PDCP SDUs with consecutive COUNT values ​​have been transmitted.

[0563] The RX_DELIV value is updated to the COUNT value of the first PDCP SDU that is equal to or greater than RX_REORD and has not yet been transmitted to a higher layer.

[0564] - If RX_DELIV is less than the RX_NEXT value,

[0565] ■RX_REORD value is updated to RX_NEXT value.

[0566] ■t-Reordering timer starts.

[0567] In addition, the present disclosure proposes the following (3-2) embodiment of a receiving PDCP entity (PDCP layer) for SRB or DRB to prevent attacks that cause data loss due to abuse of integrity protection or authentication procedures and overlap detection procedures as described above. Specifically, in the overlap detection process, if a COUNT value corresponding to the currently received data has been previously received, and data corresponding to the COUNT value has been previously successfully received (in the case where integrity protection or authentication procedures are configured, if data corresponding to the COUNT value has been previously received and the integrity verification process has been successfully performed), the receiving PDCP entity (PDCP layer) can determine that overlap detection has occurred and can discard the received data to enhance the overlap detection process and prevent hacker attacks. In addition, in the case where integrity protection or authentication procedures are not configured, if a COUNT value corresponding to the currently received data has been previously received, the data can be discarded immediately. The successful reception of data may indicate: the data corresponding to the COUNT value has been processed and stored in the buffer; the data has been received, processed and transmitted to a higher layer; the data has been transmitted to a higher layer and has been discarded; or, in the case where integrity protection or authentication procedures are configured, integrity verification has been successfully performed on the data corresponding to the COUNT value. That is, it can be determined that the integrity verification failure of the received data due to a hacker attack has not been successfully received by the data, thereby preventing normal data from being discarded during the overlap detection process. The specific process of the (3-2) embodiment of the receiving PDCP entity (PDCP layer) proposed by the present disclosure is as follows.

[0568] When receiving a PDCP PDU from a lower layer, the receiving PDCP entity (PDCP layer) may determine the COUNT value of the received PDCP PDU as follows.

[0569] - If the received RCVD_SN satisfies RCVD_SN<=SN(RX_DELIV)-Window_Siz,

[0570] ■Updated to RCVD_HFN=HFN(RX_DELIV)+1.

[0571] - Otherwise, if RCVD_SN satisfies RCVD_SN>SN(RX_DELIV)+Window_Size,

[0572] ■Updated to RCVD_HFN=HFN(RX_DELIV)-1.

[0573] - In another case,

[0574] ■Updated to RCVD_HFN=HFN(RX_DELIV).

[0575] -RCVD_COUNT is determined as RCVD_COUNT = [RCVD_HFN, RCVD_SN].

[0576] After determining the COUNT value of the received PDCP PDU, the receiving PDCP entity (PDCP layer) updates the window state variable and processes the PDCP PDU as follows.

[0577] - By using the RCVD_COUNT value, for the PDCP PDU, decryption is performed and integrity verification is performed.

[0578] ■If integrity verification fails,

[0579] ◆Indicate integrity verification failure to higher layers and discard the received PDCP data PDU (the data part of the PDCP PDU).

[0580] - If RCVD_COUNT is met <RX_DELIV,

[0581] - an integrity protection or authentication procedure is configured if a PDCP PDU with the RCVD_COUNT value has been successfully received previously, and an integrity verification procedure has been successfully performed previously for the PDCP PDU corresponding to the RCVD_COUNT value, or

[0582] - If a PDCP PDU with RCVD_COUNT value has been successfully received previously and if no integrity protection or authentication procedure is configured,

[0583] ■ The received PDCP data PDU (the data part of the PDCP PDU) is discarded.

[0584] If the received PDCP PDU is not discarded, the receiving PDCP entity (PDCP layer) may operate as follows.

[0585] - The processed PDCP SDU is stored in the receive buffer.

[0586] -If RCVD_COUNT>=RX_NEXT,

[0587] ■RX_NEXT is updated to RCVD_COUNT+1.

[0588] - if an out-of-order delivery indicator (outOfOrderDelivery) has been configured (if an out-of-order delivery operation is indicated),

[0589] ■PDCP SDU is delivered to higher layers.

[0590] - If RCVD_COUNT is the same as RX_DELIV,

[0591] ■Data is transmitted to higher layers in the order of COUNT values.

[0592] ◆ Starting from the value of COUNT = RX_DELIV, all consecutive PDCP SDUs are delivered to higher layers.

[0593] ■ The RX_DELIV value is updated to the COUNT value of the first PDCP SDU which is equal to or greater than RX_DELIV and has not yet been delivered to higher layers.

[0594] - If the t-Reordering timer is running and the RX_DELIV value is equal to or greater than RX_REORD,

[0595] ■t-Reordering timer is stopped and reset.

[0596] - If the t-Reordering timer is not being operated (including when stopped under the above conditions) and RX_DELIV is less than RX_NEXT,

[0597] The RX_REORD value is updated to RX_NEXT.

[0598] ■t-Reordering timer starts.

[0599] When the PDCP reordering timer (t-Reordering) expires, the receiving PDCP entity (PDCP layer) operates as follows.

[0600] - If the header decompression process has not been applied before (that is, if data processing has not been performed on the higher layer header), the header decompression process is performed on the stored data, and the data is transmitted to the higher layer in the order of COUNT values.

[0601] ■All PDCP SDUs with COUNT values ​​less than the RX_REORD value have been transmitted.

[0602] ■ Starting from the RX_REORD value, all PDCP SDUs with consecutive COUNT values ​​have been transmitted.

[0603] - The RX_DELIV value is updated to the COUNT value of the first PDCP SDU that is equal to or greater than RX_REORD and has not yet been delivered to higher layers.

[0604] - If RX_DELIV is less than RX_NEXT,

[0605] ■RX_REORD value is updated to RX_NEXT value.

[0606] ■t-Reordering timer starts.

[0607] In addition, the present disclosure proposes the following (3-3) embodiment of a receiving PDCP entity (PDCP layer) for SRB or DRB to prevent attacks that cause data loss due to abuse of integrity protection or authentication procedures and overlap detection procedures as described above. Specifically, in the overlap detection process, if a COUNT value corresponding to the currently received data has been previously received, and data corresponding to the COUNT value has been previously successfully received (in the case where integrity protection or authentication procedures are configured, if data corresponding to the COUNT value has been previously received and the integrity verification process has been successfully performed), the receiving PDCP entity (PDCP layer) can determine that overlap detection has occurred, and can discard the received data to enhance the overlap detection process and prevent external attacks.

[0608] Specifically, in the proposed (3-3) embodiment, the receiving PDCP entity (PDCP layer) may regard the data discarded due to integrity verification failure as unreceived data or data that has never been received, and may consider the RCVD_COUNT value of the data discarded due to integrity verification failure to have never been received, wherein the RCVD_COUNT value is not updated by the window variable. Therefore, although data having the same RCVD_COUNT value as the data discarded due to integrity verification failure is received later, if the integrity verification process for it is successful, the received data can be prevented from being discarded by the overlap detection process. In addition, in the case where integrity protection or authentication process is not configured, if the COUNT value corresponding to the currently received data has been previously received, the data can be discarded immediately.

[0609] The successful reception of data may indicate: the data corresponding to the COUNT value has been processed and stored in the buffer; the data has been received, processed and transmitted to a higher layer; the data has been transmitted to a higher layer and has been discarded; or, in the case where integrity protection or authentication procedures are configured, integrity verification has been successfully performed on the data corresponding to the COUNT value. That is, it can be determined that the data has not been successfully received and the integrity verification of the received data has failed, thereby preventing normal data from being discarded during the overlap detection process. The specific process of the (3-3) embodiment of the receiving PDCP entity (PDCP layer) proposed by the present disclosure is as follows.

[0610] When receiving a PDCP PDU from a lower layer, the receiving PDCP entity (PDCP layer) may determine the COUNT value of the received PDCP PDU as follows.

[0611] - If the received RCVD_SN satisfies RCVD_SN<=SN(RX_DELIV)-Window_Size,

[0612] ■Updated to RCVD_HFN=HFN(RX_DELIV)+1.

[0613] - Otherwise, if RCVD_SN satisfies RCVD_SN>SN(RX_DELIV)+Window_Size,

[0614] ■Updated to RCVD_HFN=HFN(RX_DELIV)-1.

[0615] - In another case,

[0616] ■Updated to RCVD_HFN=HFN(RX_DELIV).

[0617] -RCVD_COUNT is determined as RCVD_COUNT = [RCVD_HFN, RCVD_SN].

[0618] After determining the COUNT value of the received PDCP PDU, the receiving PDCP entity (PDCP layer) updates the window state variable and processes the PDCP PDU as follows.

[0619] - By using the RCVD_COUNT value, for the PDCP PDU, decryption is performed and integrity verification is performed.

[0620] ■If integrity verification fails,

[0621] ◆Indicate integrity verification failure to higher layers

[0622] ◆In addition, the received PDCP data PDU (e.g., the data portion of the PDCP PDU) is discarded. In addition, the receiving PDCP entity (PDCP layer) may regard the data discarded due to the integrity verification failure as unreceived data or data that has never been received, and may regard the RCVD_COUNT value of the data discarded due to the integrity verification failure as never received, wherein the RCVD_COUNT value is not updated by the window variable. Therefore, although data having the same RCVD_COUNT value as the RCVD_COUNT value of the data discarded due to the integrity verification failure is received later, if the integrity verification process for it is successful, the received data can be prevented from being discarded by the overlap detection process.

[0623] - If RCVD_COUNT < RX_DELIV or

[0624] - If a PDCP PDU with the value of RCVD_COUNT has been successfully received previously,

[0625] ■ The received PDCP data PDU (the data part of the PDCP PDU) is discarded.

[0626] If the received PDCP PDU is not discarded, the receiving PDCP entity (PDCP layer) can operate as follows.

[0627] - The processed PDCP SDU is stored in the receive buffer.

[0628] - If RCVD_COUNT >= RX_NEXT,

[0629] ■ RX_NEXT is updated to RCVD_COUNT + 1.

[0630] - If the out-of-order delivery indicator has been configured (if out-of-order delivery operation is indicated),

[0631] ■ The PDCP SDU is delivered to the higher layer.

[0632] - If RCVD_COUNT is the same as RX_DELIV,

[0633] ■ The data is delivered to the higher layer in the order of the COUNT value.

[0634] ◆ Starting from the value of COUNT = RX_DELIV, all consecutive PDCP SDUs are delivered to the higher layer.

[0635] ■ The RX_DELIV value is updated to the COUNT value of the first PDCP SDU that is equal to or greater than RX_DELIV and has not been delivered to the higher layer.

[0636] - If the t-Reordering timer is running and the RX_DELIV value is equal to or greater than RX_REORD,

[0637] ■ The t-Reordering timer is stopped and reset.

[0638] - If the t-Reordering timer is not operating (including the case of being stopped under the above conditions) and RX_DELIV is less than RX_NEXT,

[0639] ■RX_REORD value is updated to RX_NEXT.

[0640] ■t-Reordering timer starts.

[0641] When the PDCP reordering timer (t-Reordering) expires, the receiving PDCP entity (PDCP layer) may operate as follows.

[0642] - If the header decompression process has not been applied before (that is, if data processing has not been performed on the higher layer header), the header decompression process is performed on the stored data, and the data is transmitted to the higher layer in the order of COUNT values.

[0643] ■All PDCP SDUs with COUNT values ​​less than the RX_REORD value have been transmitted.

[0644] ■ Starting from the RX_REORD value, all PDCP SDUs with consecutive COUNT values ​​have been transmitted.

[0645] - The RX_DELIV value is updated to the COUNT value of the first PDCP SDU that is equal to or greater than RX_REORD and has not yet been delivered to higher layers.

[0646] - If the RX_DELIV value is less than the RX_NEXT value,

[0647] ■RX_REORD value is updated to RX_NEXT value.

[0648] ■t-Reordering timer starts.

[0649] Therefore, the present disclosure proposes the following fourth embodiment of a receiving PDCP entity (PDCP layer) for SRB or DRB to prevent attacks that cause data loss due to the abuse of the integrity protection or authentication process and the overlap detection process as described above. Specifically, in the overlap detection process, if a COUNT value corresponding to the currently received data has been previously received, and the data corresponding to the COUNT value has been successfully received previously, rather than simply received, and has never been discarded, the receiving PDCP entity (PDCP layer) can determine that overlap detection has occurred, and can discard the received data to enhance the overlap detection process and prevent external attacks. Successful reception of data can indicate: data corresponding to the COUNT value has been processed and stored in a buffer; data has been received, processed and transmitted to a higher layer; data has been transmitted to a higher layer and has been discarded; or, in the case where integrity protection or authentication processes are configured, integrity verification has been successfully performed on the data corresponding to the COUNT value. That is, it can be determined that the integrity verification failure of the data received due to the external attack is not successfully received by the data, and the normal data having the same COUNT value as the COUNT value of the data discarded due to the integrity verification failure is not considered as overlapping data, so the normal data can be prevented from being discarded during the overlap detection process. The specific process of the fourth embodiment of the receiving PDCP entity (PDCP layer) proposed in the present disclosure is as follows.

[0650] When receiving a PDCP PDU from a lower layer, the receiving PDCP entity (PDCP layer) may determine the COUNT value of the received PDCP PDU as follows.

[0651] - If the received RCVD_SN satisfies RCVD_SN<=SN(RX_DELIV)-Window_Size,

[0652] ■Updated to RCVD_HFN=HFN(RX_DELIV)+1.

[0653] - Otherwise, if RCVD_SN satisfies RCVD_SN>SN(RX_DELIV)+Window_Size,

[0654] ■Updated to RCVD_HFN=HFN(RX_DELIV)-1.

[0655] - In another case,

[0656] ■Updated to RCVD_HFN=HFN(RX_DELIV).

[0657] - The RCVD_COUNT is determined as RCVD_COUNT = [RCVD_HFN, RCVD_SN].

[0658] After the COUNT value of the received PDCP PDU is determined, the receiving PDCP entity (PDCP layer) may update the window status variable and process the PDCP PDU as follows.

[0659] - Using the RCVD_COUNT value, for the PDCP PDU, decryption is performed and integrity verification is carried out.

[0660] ■ If the integrity verification fails,

[0661] ◆ Indicate to the higher layer that the integrity verification fails, and discard the received PDCP data PDU (the data part of the PDCP PDU).

[0662] - If RCVD_COUNT < RX_DELIV or

[0663] - If the PDCP PDU with the RCVD_COUNT value has been successfully received previously and has never been discarded,

[0664] ■ The received PDCP data PDU (the data part of the PDCP PDU) is discarded.

[0665] If the received PDCP PDU is not discarded, the receiving PDCP entity (PDCP layer) may operate as follows.

[0666] - The processed PDCP SDU is stored in the receive buffer.

[0667] - If RCVD_COUNT >= RX_NEXT,

[0668] ■ RX_NEXT is updated to RCVD_COUNT + 1.

[0669] - If the out-of-order delivery indicator has been configured (if out-of-order delivery operation is indicated),

[0670] ■ The PDCP SDU is delivered to the higher layer.

[0671] - If RCVD_COUNT is the same as RX_DELIV,

[0672] ■ The data is delivered to the higher layer in the order of the COUNT value.

[0673] ◆ Starting from the value of COUNT = RX_DELIV, all consecutive PDCP SDUs are delivered to the higher layer.

[0674] ■ The RX_DELIV value is updated to the COUNT value of the first PDCP SDU which is equal to or greater than RX_DELIV and has not yet been delivered to higher layers.

[0675] - If the t-Reordering timer is running and the RX_DELIV value is equal to or greater than RX_REORD,

[0676] ■t-Reordering timer is stopped and reset.

[0677] - If the t-Reordering timer is not being operated (including when stopped under the above conditions) and RX_DELIV is less than RX_NEXT,

[0678] ■RX_REORD value is updated to RX_NEXT.

[0679] ■t-Reordering timer starts.

[0680] When the PDCP reordering timer (t-Reordering) expires, the receiving PDCP entity (PDCP layer) may operate as follows.

[0681] - If the header decompression process has not been applied before (that is, if data processing has not been performed on the higher layer header), the header decompression process is performed on the stored data, and the data is transmitted to the higher layer in the order of COUNT values.

[0682] ■All PDCP SDUs with COUNT values ​​less than the RX_REORD value have been transmitted.

[0683] ■ Starting from the RX_REORD value, all PDCP SDUs with consecutive COUNT values ​​have been transmitted.

[0684] - The RX_DELIV value is updated to the COUNT value of the first PDCP SDU that is equal to or greater than RX_REORD and has not yet been delivered to higher layers.

[0685] - If the RX_DELIV value is less than the RX_NEXT value,

[0686] ■RX_REORD value is updated to RX_NEXT value.

[0687] ■t-Reordering timer starts.

[0688] In the above process, for example, the first received PDCP PDU is successfully received and can be delivered to a higher layer and then discarded. If an overlapping packet identical to the first PDCP PDU is received later, the overlapping packet identical to the first PDCP PDU is not discarded by the overlap detection process, but can be discarded while being regarded as out-of-window data because the overlapping packet is outside the PDCP reception window. This is because, in the case where the first received PDCP PDU is successfully received and delivered to a higher layer, the PDCP reception window moves in the direction in which the COUNT value increases.

[0689] The fifth embodiment of the operation of the receiving PDCP entity (PDCP layer) of the terminal or base station proposed by the present disclosure is as follows. In the fifth embodiment, in the absence of configuration integrity verification, overlapping data and out-of-window data are immediately discarded without performing a decryption operation, thereby preventing unnecessary decryption operations.

[0690] When receiving a PDCP PDU from a lower layer, the receiving PDCP entity (PDCP layer) may determine the COUNT value of the received PDCP PDU as follows.

[0691] - If the received RCVD_SN satisfies RCVD_SN<=SN(RX_DELIV)-Window_Size,

[0692] ■Updated to RCVD_HFN=HFN(RX_DELIV)+1.

[0693] - Otherwise, if RCVD_SN satisfies RCVD_SN>SN(RX_DELIV)+Window_Size,

[0694] ■Updated to RCVD_HFN=HFN(RX_DELIV)-1.

[0695] - In another case,

[0696] ■Updated to RCVD_HFN=HFN(RX_DELIV).

[0697] -RCVD_COUNT is determined as RCVD_COUNT = [RCVD_HFN, RCVD_SN].

[0698] After the COUNT value of the received PDCP PDU is determined, the receiving PDCP entity (PDCP layer) may update the window state variable and process the PDCP PDU as follows.

[0699] - If the integrity protection or authentication process is configured for the PDCP PDU using the RCVD_COUNT value, decryption is performed and integrity verification is carried out.

[0700] ■ If the integrity verification fails,

[0701] ◆ Indicate to the higher layer that the integrity verification has failed, and discard the received PDCP data PDU (the data part of the PDCP PDU).

[0702] - If RCVD_COUNT < RX_DELIV is satisfied or

[0703] - If a PDCP PDU with the RCVD_COUNT value has been previously received, and if, in the case where the integrity protection or authentication process is configured, the integrity verification process for the PDCP PDU corresponding to the RCVD_COUNT value has been successfully executed previously,

[0704] ■ The received PDCP data PDU (the data part of the PDCP PDU) is discarded.

[0705] If the received PDCP PDU is not discarded, the receiving PDCP entity (PDCP layer) operates as follows.

[0706] - If the integrity protection or authentication process is not configured (or the decryption process is not executed), decrypt the PDCP PDU using the value of RCVD_COUNT.

[0707] - The processed PDCP SDU is stored in the receive buffer.

[0708] - If RCVD_COUNT >= RX_NEXT is satisfied,

[0709] ■ RX_NEXT is updated to RCVD_COUNT + 1.

[0710] - If the out-of-order delivery indicator has been configured (if out-of-order delivery operation is indicated),

[0711] ■ The PDCP SDU is delivered to the higher layer.

[0712] - If RCVD_COUNT is the same as RX_DELIV,

[0713] ■ After performing header decompression without canceling header compression, the data is delivered to the higher layer in the order of the COUNT value.

[0714] ◆ Starting from the value of COUNT = RX_DELIV, all consecutive PDCP SDUs are delivered to higher layers.

[0715] ■ The RX_DELIV value is updated to the COUNT value of the first PDCP SDU which is equal to or greater than RX_DELIV and has not yet been delivered to higher layers.

[0716] - If the t-Reordering timer is running and the RX_DELIV value is equal to or greater than RX_REORD,

[0717] ■t-Reordering timer is stopped and reset.

[0718] - If the t-Reordering timer is not being operated (including when stopped under the above conditions) and RX_DELIV is less than RX_NEXT,

[0719] ■RX_REORD value is updated to RX_NEXT.

[0720] ■t-Reordering timer starts.

[0721] When the PDCP reordering timer (t-Reordering) expires, the receiving PDCP entity (PDCP layer) may operate as follows.

[0722] -After performing header decompression without canceling header compression, the data is transmitted to the higher layer in the order of COUNT value.

[0723] ■All PDCP SDUs with COUNT values ​​less than the RX_REORD value have been transmitted.

[0724] ■ Starting from the RX_REORD value, all PDCP SDUs with consecutive COUNT values ​​have been transmitted.

[0725] - The RX_DELIV value is updated to the COUNT value of the first PDCP SDU that is equal to or greater than RX_REORD and has not yet been delivered to higher layers.

[0726] - If the RX_DELIV value is less than the RX_NEXT value,

[0727] ■RX_REORD value is updated to RX_NEXT value.

[0728] ■t-Reordering timer starts.

[0729] The (5-2) embodiment of the operation of the receiving PDCP entity (PDCP layer) of the terminal or base station proposed by the present disclosure is as follows. In the (5-2) embodiment, when integrity verification is not configured, overlapping data and out-of-window data are immediately discarded without performing decryption operations, thereby preventing unnecessary decryption operations.

[0730] When receiving a PDCP PDU from a lower layer, the receiving PDCP entity (PDCP layer) may determine the COUNT value of the received PDCP PDU as follows.

[0731] - If the received RCVD_SN satisfies RCVD_SN<=SN(RX_DELIV)-Window_Size,

[0732] ■Updated to RCVD_HFN=HFN(RX_DELIV)+1.

[0733] - Otherwise, if RCVD_SN satisfies RCVD_SN>SN(RX_DELIV)+Window_Size,

[0734] ■Updated to RCVD_HFN=HFN(RX_DELIV)-1.

[0735] - In another case,

[0736] ■Updated to RCVD_HFN=HFN(RX_DELIV).

[0737] -RCVD_COUNT is determined as RCVD_COUNT = [RCVD_HFN, RCVD_SN].

[0738] After the COUNT value of the received PDCP PDU is determined, the receiving PDCP entity (PDCP layer) may update the window state variable and process the PDCP PDU as follows.

[0739] - If integrity protection or authentication procedures are configured for the PDCP PDU using the RCVD_COUNT value, decryption and integrity verification are performed.

[0740] ■If integrity verification fails,

[0741] ◆Indicate integrity verification failure to higher layers and discard the received PDCP data PDU (data part of PDCP PDU).

[0742] - If RCVD_COUNT is met <RX_DELIV,

[0743] - an integrity protection or authentication procedure is configured if a PDCP PDU with the RCVD_COUNT value has been successfully received previously, and an integrity verification procedure has been successfully performed previously for the PDCP PDU corresponding to the RCVD_COUNT value, or

[0744] - If a PDCP PDU with RCVD_COUNT value has been successfully received previously and if no integrity protection or authentication procedure is configured,

[0745] ■ The received PDCP data PDU (the data part of the PDCP PDU) is discarded.

[0746] If the received PDCP PDU is not discarded, the receiving PDCP entity (PDCP layer) operates as follows.

[0747] - If integrity protection or authentication procedure is not configured (or decryption procedure is not performed), decryption is performed on the PDCP PDU using the value of RCVD_COUNT.

[0748] - The processed PDCP SDU is stored in the receive buffer.

[0749] -If RCVD_COUNT>=RX_NEXT,

[0750] ■RX_NEXT is updated to RCVD_COUNT+1.

[0751] - if an out-of-order delivery indicator (outOfOrderDelivery) has been configured (if an out-of-order delivery operation is indicated),

[0752] ■PDCP SDU is delivered to higher layers.

[0753] - If RCVD_COUNT is the same as RX_DELIV,

[0754] ■After performing header decompression without canceling header compression, the data is transmitted to the higher layer in the order of COUNT value.

[0755] ◆ Starting from the value of COUNT = RX_DELIV, all consecutive PDCP SDUs are delivered to higher layers.

[0756] ■ The RX_DELIV value is updated to the COUNT value of the first PDCP SDU which is equal to or greater than RX_DELIV and has not yet been delivered to higher layers.

[0757] - If the t-Reordering timer is running and the RX_DELIV value is equal to or greater than RX_REORD,

[0758] ■t-Reordering timer is stopped and reset.

[0759] - If the t-Reordering timer is not being operated (including when stopped under the above conditions) and RX_DELIV is less than RX_NEXT,

[0760] The RX_REORD value is updated to RX_NEXT.

[0761] ■t-Reordering timer starts.

[0762] When the PDCP reordering timer (t-Reordering) expires, the receiving PDCP entity (PDCP layer) may operate as follows.

[0763] -After performing header decompression without canceling header compression, the data is transmitted to the higher layer in the order of COUNT value.

[0764] ■All PDCP SDUs with COUNT values ​​less than the RX_REORD value have been transmitted.

[0765] ■ Starting from the RX_REORD value, all PDCP SDUs with consecutive COUNT values ​​have been transmitted.

[0766] - The RX_DELIV value is updated to the COUNT value of the first PDCP SDU that is equal to or greater than RX_REORD and has not yet been delivered to higher layers.

[0767] - If RX_DELIV is less than RX_NEXT,

[0768] ■RX_REORD value is updated to RX_NEXT value.

[0769] ■t-Reordering timer starts.

[0770] The (5-3)th embodiment of the operation of the receiving PDCP entity (PDCP layer) of the terminal or base station proposed by the present disclosure is as follows. In the (5-3)th embodiment, when integrity verification is not configured, overlapping data and out-of-window data are immediately discarded without performing decryption operations, thereby preventing unnecessary decryption operations. In addition, the receiving PDCP entity (PDCP layer) may regard data discarded due to integrity verification failure as unreceived data or data that has never been received, and may consider the RCVD_COUNT value of the data discarded due to integrity verification failure to have never been received, wherein the RCVD_COUNT value is not updated by the window variable. Therefore, although data having the same RCVD_COUNT value as the RCVD_COUNT value of the data discarded due to integrity verification failure is received later, if the integrity verification process is successful, the received data can be prevented from being discarded by the overlap detection process.

[0771] When receiving a PDCP PDU from a lower layer, the receiving PDCP entity (PDCP layer) may determine the COUNT value of the received PDCP PDU as follows.

[0772] - If the received RCVD_SN satisfies RCVD_SN<=SN(RX_DELIV)-Window_Size,

[0773] ■Updated to RCVD_HFN=HFN(RX_DELIV)+1.

[0774] - Otherwise, if RCVD_SN satisfies RCVD_SN>SN(RX_DELIV)+Window_Size,

[0775] ■Updated to RCVD_HFN=HFN(RX_DELIV)-1.

[0776] - In another case,

[0777] ■Updated to RCVD_HFN=HFN(RX_DELIV).

[0778] -RCVD_COUNT is determined as RCVD_COUNT = [RCVD_HFN, RCVD_SN].

[0779] After the COUNT value of the received PDCP PDU is determined, the receiving PDCP entity (PDCP layer) may update the window state variable and process the PDCP PDU as follows.

[0780] - If integrity protection or authentication procedures are configured,

[0781] ■For PDCP PDUs, decryption is performed and integrity verification is performed by using the RCVD_COUNT value.

[0782] ■If the integrity verification fails,

[0783] ◆Indicate to the higher layer that the integrity verification has failed.

[0784] ◆In addition, the received PDCP data PDU (e.g., the data part of the PDCP PDU) is discarded. In addition, the receiving PDCP entity (PDCP layer) may consider the data discarded due to integrity verification failure as data that has not been received or has never been received, and may consider that the RCVD_COUNT value of the data discarded due to integrity verification failure has never been received, where the RCVD_COUNT value is not updated by the window variable. Therefore, although data with the same RCVD_COUNT value as the data discarded due to integrity verification failure is received later, if the integrity verification process for it is successful, the received data can be prevented from being discarded through the overlap detection process.

[0785] - If RCVD_COUNT < RX_DELIV is satisfied or

[0786] - If a PDCP PDU with the RCVD_COUNT value has been received previously,

[0787] ■The received PDCP data PDU (the data part of the PDCP PDU) is discarded.

[0788] If the received PDCP PDU is not discarded, the receiving PDCP entity (PDCP layer) may operate as follows.

[0789] - If integrity protection or authentication procedures are not configured (or the decryption procedure is not performed),

[0790] ■Decrypt the PDCP PDU by using the value of RCVD_COUNT.

[0791] - The processed PDCP SDU is stored in the receive buffer.

[0792] - If RCVD_COUNT >= RX_NEXT is satisfied,

[0793] ■RX_NEXT is updated to RCVD_COUNT + 1.

[0794] - If an out-of-order delivery indicator has been configured (if out-of-order delivery operation is indicated),

[0795] ■PDCP SDU is delivered to higher layers.

[0796] - If RCVD_COUNT is the same as RX_DELIV,

[0797] ■After performing header decompression without canceling header compression, the data is transmitted to the higher layer in the order of COUNT value.

[0798] ◆ Starting from the value of COUNT = RX_DELIV, all consecutive PDCP SDUs are delivered to higher layers.

[0799] ■ The RX_DELIV value is updated to the COUNT value of the first PDCP SDU which is equal to or greater than RX_DELIV and has not yet been delivered to higher layers.

[0800] - If the t-Reordering timer is running and the RX_DELIV value is equal to or greater than RX_REORD,

[0801] ■t-Reordering timer is stopped and reset.

[0802] - If the t-Reordering timer is not being operated (including when stopped under the above conditions) and RX_DELIV is less than RX_NEXT,

[0803] ■RX_REORD value is updated to RX_NEXT.

[0804] ■t-Reordering timer starts.

[0805] When the PDCP reordering timer (t-Reordering) expires, the receiving PDCP entity (PDCP layer) may operate as follows.

[0806] -After performing header decompression without canceling header compression, the data is delivered to the higher layer in the order of COUNT value.

[0807] ■All PDCP SDUs with COUNT values ​​less than the RX_REORD value have been transmitted.

[0808] ■ Starting from the RX_REORD value, all PDCP SDUs with consecutive COUNT values ​​have been transmitted.

[0809] - The RX_DELIV value is updated to the COUNT value of the first PDCP SDU that is equal to or greater than RX_REORD and has not yet been delivered to higher layers.

[0810] - If the RX_DELIV value is less than the RX_NEXT value,

[0811] ■RX_REORD value is updated to RX_NEXT value.

[0812] ■t-Reordering timer starts.

[0813] Figure 2H A diagram showing the operation of a receiving PDCP entity (PDCP layer) of a terminal proposed in the present disclosure.

[0814] In an embodiment of the receiving PDCP entity (PDCP layer) proposed in the present disclosure, specifically, the receiving PDCP entity (PDCP layer) can receive data from a lower layer device (2h-05), and can perform a decryption process on the data (2h-10).

[0815] In addition, if integrity protection is configured, the receiving PDCP entity (PDCP layer) can perform an integrity verification process on the data (2h-15).

[0816] In addition, if the integrity verification fails, the receiving PDCP entity (PDCP layer) may discard the data (2h-20).

[0817] If the integrity verification is successful, the receiving PDCP entity (PDCP layer) can identify whether the data is out-of-window data or data that has been successfully received previously (2h-25).

[0818] If the data is out-of-window data or data that has been successfully received previously, the receiving PDCP entity (PDCP layer) may discard the data (2h-30).

[0819] Otherwise, if the header or data compression function is configured, the receiving PDCP entity (PDCP layer) can apply the decompression process (2h-35) and can transmit the data to the higher layer in sequence (2h-40).

[0820] Fig.2I The structure of a terminal or a radio node to which the embodiments are applicable is shown.

[0821] refer to Fig.2I The terminal includes a radio frequency (RF) processor 2i-10, a baseband processor 2i-20, a memory 2i-30 and a controller 2i-40.

[0822] The radio frequency (RF) processor 2i-10 performs functions such as frequency band conversion and amplification of signals for sending or receiving signals through a radio channel. That is, the RF processor 2i-10 up-converts the baseband signal provided by the baseband processor 2i-20 into an RF band signal, then transmits the baseband signal through an antenna, and down-converts the RF band signal received through the antenna into a baseband signal. For example, the RF processor 2i-10 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a digital-to-analog converter (DAC), an analog-to-digital converter (ADC), and the like. Fig.2I Only one antenna is shown, but the terminal may include multiple antennas. In addition, the RF processor 2i-10 may include multiple RF chains. In addition, the RF processor 2i-10 can perform beamforming. For beamforming, the RF processor 2i-10 can adjust the phase and size of each signal sent or received by multiple antennas or antenna elements. In addition, the RF processor can perform MIMO operations and receive multiple layers when performing MIMO operations. The RF processor 2i-10 can appropriately configure multiple antennas or antenna elements according to the control of the controller to perform receive beam scanning, or can adjust the direction and beam width of the receive beam so that the receive beam is consistent with the transmit beam.

[0823] The baseband processor 2i-20 performs the conversion function between the baseband signal and the bit stream according to the physical layer standard of the system. For example, when data is sent, the baseband processor 2i-20 generates complex symbols by encoding and modulating the sending bit stream. In addition, when data is received, the baseband processor 2i-20 recovers the received bit stream by demodulating and decoding the baseband signal provided by the RF processor 2i-10. For example, according to the orthogonal frequency division multiplexing (OFDM) scheme, when data is sent, the baseband processor 2i-20 generates complex symbols by encoding and modulating the sending bit stream, maps the complex symbols to subcarriers, and then configures OFDM symbols through inverse fast Fourier transform (IFFT) operations and cyclic prefix (CP) insertion. In addition, when data is received, the baseband processor 2i-20 divides the baseband signal provided by the RF processor 2i-10 into OFDM symbol units, recovers the signal mapped to the subcarrier through a fast Fourier transform (FFT) operation, and then recovers the received bit stream through demodulation and decoding.

[0824] As described above, the baseband processor 2i-20 and the RF processor 2i-10 send and receive signals. Therefore, each of the baseband processor 2i-20 and the RF processor 2i-10 can be referred to as a transmitter, a receiver, a transceiver or a communicator. In addition, at least one of the baseband processor 2i-20 or the RF processor 2i-10 may include a plurality of communication modules to support a plurality of radio access technologies that are different from each other. In addition, at least one of the baseband processor 2i-20 and the RF processor 2i-10 may include communication modules that are different from each other to process signals of different frequency bands. For example, radio access technologies that are different from each other may include LTE networks, NR networks, etc. In addition, frequency bands that are different from each other may include ultra-high frequency (SHF) (e.g., 2.2 GHz and 2 GHz) bands and millimeter (mm) wave (e.g., 60 GHz) bands.

[0825] The memory 2i-30 stores data such as basic programs, application programs, and configuration information for terminal operation. The memory 2i-30 provides the stored data according to a request from the controller 2i-40.

[0826] The controller 2i-40 controls the overall operation of the terminal. For example, the controller 2i-40 sends or receives a signal through the baseband processor 2i-20 and the RF processor 2i-10. In addition, the controller 2i-40 records data to the memory 2i-30 and reads data from the memory 2i-30. To this end, the controller 2i-40 may include at least one processor. For example, the controller 2i-40 may include a communication processor (CP) for performing communication control and an application processor (AP) for controlling a higher layer such as an application.

[0827] Figure 2J A block diagram showing the configuration of a TRP or a radio node in a radio communication system to which the embodiments are applicable.

[0828] like Figure 2J As shown, the base station is configured to include an RF processor 2j-10, a baseband processor 2j-20, a backhaul transceiver 2j-30, a memory 2j-40 ​​and a controller 2j-50.

[0829] The RF processor 2j-10 performs functions such as frequency band conversion and amplification of signals for transmitting or receiving signals through a radio channel. That is, the RF processor 2j-10 up-converts the baseband signal provided by the baseband processor 2j-20 into an RF band signal, then transmits the baseband signal through an antenna, and down-converts the RF band signal received through the antenna into a baseband signal. For example, the RF processor 2j-10 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, and the like. Figure 2JOnly one antenna is shown, but the first access node may include multiple antennas. In addition, the RF processor 2j-10 may include multiple RF chains. In addition, the RF processor 2j-10 can perform beamforming. For beamforming, the RF processor 2j-10 can adjust the phase and size of each signal sent or received through multiple antennas or antenna elements. The RF processor can perform downward MIMO operations by sending one or more layers.

[0830] The baseband processor 2j-20 performs the conversion function between the baseband signal and the bit stream according to the physical layer standard of the first radio access technology. For example, when data is sent, the baseband processor 2j-20 generates complex symbols by encoding and modulating the sending bit stream. In addition, when data is received, the baseband processor 2j-20 recovers the received bit stream by demodulating and decoding the baseband signal provided by the RF processor 2j-10. For example, according to the OFDM scheme, when data is sent, the baseband processor 2j-20 generates complex symbols by encoding and modulating the sending bit stream, maps the complex symbols to subcarriers, and then configures OFDM symbols via IFFT operation and CP insertion. In addition, when data is received, the baseband processor 2j-20 divides the baseband signal provided by the RF processor 2j-10 into OFDM symbol units, recovers the signal mapped to the subcarrier through FFT operation, and then recovers the received bit stream through demodulation and decoding. As described above, the baseband processor 2j-20 and the RF processor 2j-10 send and receive signals. Thus, each of the baseband processor 2j-20 and the RF processor 2j-10 can be referred to as a transmitter, a receiver, a transceiver, a communicator, or a radio communicator.

[0831] Transceiver 2j-30 provides an interface for performing communications with other nodes in the network.

[0832] The memory 2j-40 ​​stores data such as basic programs, applications, and configuration information for the operation of the main base station. In particular, the memory 2j-40 ​​can store information about the bearer assigned to the connection terminal, the measurement results reported by the connection terminal, etc. In addition, the memory 2j-40 ​​can store information that is a criterion for determining whether to provide or interrupt multiple connections for the terminal. In addition, the memory 2j-40 ​​provides the stored data according to a request from the controller 2j-50.

[0833] The controller 2j-50 controls the overall operation of the main base station. For example, the controller 2j-50 sends or receives a signal through the baseband processor 2j-20 and the RF processor 2j-10 or through the backhaul transceiver 2j-30. In addition, the controller 2j-50 records data to the memory 2j-40 ​​and reads data from the memory 2j-40. To this end, the controller 2j-50 may include at least one processor.

[0834] Although the present disclosure has been described with various embodiments, various changes and modifications may be suggested to one skilled in the art. The present disclosure is intended to encompass such changes and modifications as fall within the scope of the appended claims.

Claims

1. A method performed by a terminal in a wireless communication system, the method comprising: A radio resource control (RRC) message for configuring a dual connectivity (DC) for a terminal is received from a first base station, wherein: The first base station operates as a primary cell group MCG of DC, and the second base station operates as a secondary cell group SCG of DC; receiving an RRC release message from the first base station to suspend the RRC connection; In case the RRC connection is suspended, the configuration of the SCG is stored in the terminal context; receiving an RRC resume message from the first base station to resume the suspended RRC connection; as well as In case that the RRC recovery message includes the first information indicating to maintain the configuration of the SCG, the configuration of the SCG stored in the terminal context is maintained based on the first information.

2. The method according to claim 1, in, The RRC recovery message further includes second information and third information, the second information indicating that the configuration of at least one secondary cell SCell of the MCG is maintained, the third information indicating that the SCell is to be activated, and Wherein, the configuration of at least one SCell of the MCG is maintained based on the second information, and the SCell is activated based on the third information.

3. The method according to claim 1, further comprising: identifying whether the RRC resume message indicates activation of the SCG; and In case the RRC recovery message indicates activation of the SCG, a random access procedure with the second base station is performed.

4. The method according to claim 1, further comprising: Sending an RRC recovery request message to the first base station, wherein: The RRC resume message is received as a response to the RRC resume request message; as well as Measurement is performed based on the measurement configuration information included in the RRC resume message.

5. A method performed by a first base station in a wireless communication system, the method comprising: Sending a radio resource control RRC message for configuring dual connectivity DC for the terminal to the terminal, wherein the first base station operates as a primary cell group MCG of the DC, and the second base station operates as a secondary cell group SCG of the DC; Sending an RRC release message to the terminal to suspend the RRC connection; and Sending an RRC resume message to the terminal to resume the suspended RRC connection, the RRC resume message including first information, the first information indicating to maintain the configuration of the SCG stored in the terminal context based on the suspension of the RRC connection, in, Based on the first information included in the RRC resume message, the configuration of the SCG is maintained in the terminal context.

6. The method according to claim 5, in, The RRC recovery message further includes second information and third information, wherein the second information indicates that the configuration of at least one secondary cell SCell of the MCG is maintained, and the third information indicates that the SCell is to be activated, and The configuration of at least one SCell based on the second information MCG is maintained in the terminal context, and the SCell is activated based on the third information SCell.

7. The method according to claim 5, in, In case the RRC recovery message indicates activation of the SCG, a random access procedure is performed between the terminal and the second base station.

8. The method according to claim 5, further comprising: Receive an RRC recovery request message from the terminal, in, sending the RRC resume message as a response to the RRC resume request message, and The RRC recovery message also includes measurement configuration information.

9. A terminal in a wireless communication system, the terminal comprising: transceiver; and The controller is configured as: The control transceiver receives a radio resource control RRC message for configuring dual connectivity DC for the terminal from the first base station, wherein: The first base station operates as a primary cell group MCG of DC, and the second base station operates as a secondary cell group SCG of DC; Controlling the transceiver to receive an RRC release message from the first base station to suspend the RRC connection; In case the RRC connection is suspended, the configuration of the SCG is stored in the terminal context; controlling the transceiver to receive an RRC resume message from the first base station to resume the suspended RRC connection; and In case that the RRC recovery message includes the first information indicating to maintain the configuration of the SCG, the configuration of the SCG stored in the terminal context is maintained based on the first information.

10. The terminal according to claim 9, in, The RRC recovery message further includes second information and third information, the second information indicating that the configuration of at least one secondary cell SCell of the MCG is maintained, the third information indicating that the SCell is to be activated, and Wherein, the configuration of at least one SCell of the MCG is maintained based on the second information, and the SCell is activated based on the third information.

11. The terminal according to claim 9, wherein: The controller is also configured to: identifying whether the RRC resume message indicates activation of the SCG; and In case the RRC recovery message indicates activation of the SCG, a random access procedure with the second base station is performed.

12. The terminal according to claim 9, in, The controller is further configured to control the transceiver to send an RRC recovery request message to the first base station, and perform measurement based on measurement configuration information included in the RRC recovery message, and The RRC recovery message is received as a response to the RRC recovery request message.

13. A first base station in a wireless communication system, the first base station comprising: transceiver; and The controller is configured as: Controlling the transceiver to send a radio resource control RRC message for configuring dual connectivity DC for the terminal to the terminal, wherein the first base station operates as a primary cell group MCG of the DC, and the second base station operates as a secondary cell group SCG of the DC; controlling the transceiver to send an RRC release message to the terminal to suspend the RRC connection; and controlling the transceiver to send an RRC resume message to the terminal to resume the suspended RRC connection, the RRC resume message including first information, the first information indicating to maintain the configuration of the SCG stored in the terminal context based on the suspension of the RRC connection, in, Based on the first information included in the RRC resume message, the configuration of the SCG is maintained in the terminal context.

14. The first base station according to claim 13, in, The RRC recovery message further includes second information and third information, wherein the second information indicates that the configuration of at least one secondary cell SCell of the MCG is maintained, and the third information indicates that the SCell is to be activated, and The configuration of at least one SCell based on the second information MCG is maintained in the terminal context, and the SCell is activated based on the third information SCell.

15. The first base station according to claim 13, in, In case the RRC recovery message indicates activation of the SCG, a random access procedure is performed between the terminal and the second base station.

16. The first base station according to claim 13, in, The controller is further configured to control the transceiver to receive an RRC recovery request message from the terminal, and to send the RRC recovery message as a response to the RRC recovery request message, and The RRC recovery message also includes measurement configuration information.

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