Method and apparatus for controlling multiple timers and multiple bearers for rrc connection resume and data transmission in mobile wireless communications

Abstract

According to an embodiment of the disclosure, a method of resuming an RRC connection by a terminal can include receiving a first downlink control message from a first cell, receiving system information from a second cell, initiating a resumption procedure by the second cell, transmitting first uplink control information, receiving second downlink control information, wherein during the first resumption procedure, the first timer is stopped when the second downlink control message is received, and during the second resumption procedure, the first timer is started before radio bearer configuration is applied and radio bearer is resumed, and during the second resumption procedure, the third timer is started before radio bearer configuration is applied and radio bearer is resumed, and the third timer is stopped before cell group configuration is applied when the second downlink control message is received.

Description

Technical Field

[0001] This disclosure relates to a method and apparatus for changing a secondary base station in a wireless communication system. Background Technology

[0002] To meet the ever-increasing demand for wireless data traffic since the commercialization of fourth-generation (4G) communication systems, fifth-generation (5G) systems are under development. For high performance, 5G systems introduce millimeter-wave (mmW) bands (e.g., the 60GHz band). To increase propagation distance by mitigating propagation loss in 5G communication systems, various technologies such as beamforming, massive MIMO, full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and large antennas have been introduced. Furthermore, for better scalability, base stations are divided into a central unit and multiple distributed units. To facilitate the introduction of various services, the goal of 5G communication systems is to support higher data rates and lower latency. Summary of the Invention

[0003] Technical issues The disclosed embodiments aim to provide a method and apparatus for restoring an RRC connection and transmitting and receiving data in a wireless communication system. In particular, a method and apparatus are provided for controlling a timer and a radio bearer to execute, error-free, a first process of transmitting and receiving data after a state transition and a second process of transmitting and receiving data without a state transition.

[0004] Solution According to embodiments of this disclosure, a method for restoring an RRC connection by a terminal is provided. The method may include: receiving a first downlink control message from a first cell; receiving system information from a second cell; initiating a recovery process by the second cell; sending first uplink control information; and receiving second downlink control information. During the first recovery process, upon receiving the second downlink control message, a first timer is stopped. During the second recovery process, during the second recovery process, the first timer is started before restoring the radio bearer after applying radio bearer configuration. During the second recovery process, during the second recovery process, a third timer is started before restoring the radio bearer after applying radio bearer configuration. Upon receiving the second downlink control message, the third timer is stopped before applying cell group configuration.

[0005] Beneficial effects The disclosed embodiments provide a method and apparatus for restoring an RRC connection and sending and receiving data in a wireless communication system. Attached Figure Description

[0006] Figure 1a This is a diagram illustrating the architecture of the 5G system and NG-RAN that can be applied to this disclosure.

[0007] Figure 1b This is a diagram illustrating the wireless protocol architecture that can be applied in a 5G system according to this disclosure.

[0008] Figure 1c This is a diagram illustrating the RRC state transitions.

[0009] Figure 2a This is a diagram illustrating the operation of a terminal and a base station according to an embodiment of the present invention.

[0010] Figure 2b This is a diagram illustrating the first recovery process and the second recovery process according to an embodiment of the present invention.

[0011] Figure 2c This is a diagram showing the structure of the uplink MAC PDU used in the second recovery process.

[0012] Figure 2d This is a diagram showing the structure of a typical uplink MAC PDU.

[0013] Figure 2e This is a diagram illustrating the hierarchical structure of the security key.

[0014] Figure 2f This is a diagram showing the structure of the first BSR MAC CE and the second BSR MAC CE.

[0015] Figure 2g This is a diagram showing the structure of the third BSR MAC CE and the fourth BSR MAC CE.

[0016] Figure 2h This is a diagram illustrating the MAC-I calculation and encryption process.

[0017] Figure 3 This is a flowchart illustrating the operation of the terminal.

[0018] Figure 4a This is a block diagram illustrating the internal structure of a UE that applies this disclosure.

[0019] Figure 4b This is a block diagram illustrating the configuration of a base station according to the present disclosure. Detailed Implementation

[0020] The following description, with reference to the accompanying drawings, is provided to aid in a full understanding of the various embodiments of this disclosure as defined by the claims and their equivalents. It includes various specific details to aid understanding, but these are to be considered exemplary only. Therefore, those skilled in the art will recognize that various changes and modifications can be made to the various embodiments described herein without departing from the scope and spirit of this disclosure. Additionally, for clarity and brevity, descriptions of well-known functions and structures may be omitted.

[0021] For ease of explanation, the following description provides terms used to indicate access nodes, network entities, messages, interfaces between network entities, and various identifying information. Therefore, the terms used in the following description are not limited to their specific meanings, but may be replaced by other terms with equivalent technical meanings.

[0022] In the following description, for ease of explanation, the terms and definitions given in the 3GPP standards are used. However, this disclosure is not limited to the use of these terms and definitions, and any other arbitrary terms and definitions may be used instead.

[0023] Table 1 lists the acronyms used throughout this disclosure.

[0024] Table 2 lists the terms and their definitions used throughout this disclosure.

[0025] In this invention, "trigger" or "triggered" and "initiator" or "initiated" can be used with the same meaning.

[0026] In this invention, "radio bearer that allows a second recovery process", "radio bearer that is configured with a second recovery process" and "radio bearer that enables a second recovery process" can all have the same meaning.

[0027] Figure 1a This is a diagram illustrating the architecture of the 5G system and NG-RAN that can be applied to this disclosure.

[0028] The 5G system consists of NG-RAN (1a-01) and 5GC (1a-02). The NG-RAN node is: - gNB, providing termination of NR user plane and control plane protocols toward the UE; or - ng-eNB provides termination of E-UTRA user plane and control plane protocols toward the UE.

[0029] The gNB (1a-05 or 1a-06) and ng-eNB (1a-03 or 1a-04) interconnect via the Xn interface. The gNB and ng-eNB also connect to the 5GC via the NG interface, and more specifically, to the AMF (Access and Mobility Management Function) and UPF (User Plane Function). The AMF (1a-07) and UPF (1a-08) can be implemented as physical nodes or as separate physical nodes.

[0030] The gNB (1a-05 or 1a-06) or ng-eNB (1a-03 or 1a-04) carries the following functions.

[0031] Radio resource management functions, such as radio bearer control, radio access control, connection mobility control, and dynamic allocation of resources to the UE in the uplink, downlink, and sidelink (scheduling); IP and Ethernet header compression, uplink data decompression, and user data stream encryption; When a route to the MME cannot be determined based on the information provided by the UE, the AMF attached to the UE is selected; Routing of user plane data toward the UPF; Scheduling and transmission of paging messages; Scheduling and transmission of broadcast information (originating from AMF or O&M); Configuration for measurement and measurement reporting for mobility and scheduling; Session management; QoS flow management and mapping to data radio bearers; Supports UEs in RRC_INACTIVE state; Wireless access network sharing; Close interoperability between NR and E-UTRA; and Supports network slicing.

[0032] AMF (1a-07) carries functions such as NAS signaling, NAS signaling security, AS security control, SMF selection, authentication, mobility management and location management.

[0033] UPF (1a-08) carries functions such as packet routing and forwarding, transport class packet marking in the uplink, QoS processing and downlink, and mobility anchoring for mobility.

[0034] Figure 1b This is a diagram illustrating the wireless protocol architecture that can be applied in a 5G system according to this disclosure.

[0035] The user plane protocol stack consists of SDAP (1b-01 or 1b-02), PDCP (1b-03 or 1b-04), RLC (1b-05 or 1b-06), MAC (1b-07 or 1b-08), and PHY (1b-09 or 1b-10). The control plane protocol stack consists of NAS (1b-11 or 1b-12), RRC (1b-13 or 1b-14), PDCP, RLC, MAC, and PHY.

[0036] Each protocol sublayer performs the functions associated with the operations listed in Table 3.

[0037] Table 3 The terminal supports three RRC states. Table 4 lists the characteristics of each state.

[0038] Table 4 Figure 1c This is a diagram illustrating the RRC state transitions.

[0039] Between RRC_CONNECTED 1c-11 and RRC_INACTIVE 1c-13, a state transition occurs due to the exchange of a recovery message and a release message containing a suspended IE.

[0040] The state transition occurs between RRC_CONNECTED 1c-11 and RRC_IDLE 1c-15 through RRC connection establishment and RRC connection release.

[0041] The state transition from RRC_INACTIVE to RRC_CONNECTED involves not only signal exchange between the terminal and the base station, but also context transmission and data path changes between base stations. These additional processes are reasonable if the terminal has enough data to transmit, but otherwise, excessive overhead can reduce network efficiency.

[0042] This invention introduces a new recovery procedure that enables data transmission and reception without transitioning to the RRC_CONNECTED state. Hereinafter, the recovery procedure used to transition the terminal from the RRC_INACTIVE state to the RRC_CONNECTED state is referred to as the first recovery procedure, and the procedure for transmitting and receiving data while the terminal is in the RRC_INACTIVE state is referred to as the second recovery procedure. Through the first recovery procedure, the terminal can restore a suspended RRC connection, and through the second recovery procedure, the terminal can resume data transmission and reception. The terminal can switch to the first recovery procedure while performing the second recovery procedure.

[0043] Figure 2a is a diagram illustrating operations of a terminal and a base station according to an embodiment of the present invention.

[0044] In a wireless communication system including a terminal 2a-01, a first base station 2a-03, and a second base station 2a-05, the terminal and the base station operate as follows.

[0045] In step 2a-11: The terminal reports capabilities to the first base station or other base stations. The UE capability transfer process includes: if the serving base station transmits an RRC message requesting UE capability information, transmitting an RRC control message called UECapabilityInformation containing the UE capability information to the serving base station. UECapabilityInformation includes the following information.

[0046] <UE capability information> 1. First information related to RRC_INACTIVE: 1-bit information indicating whether the terminal supports RRC_INACTIVE. Regardless of how many frequency bands the terminal supports, only 1 bit is reported.

[0047] 2. Second information related to RRC_INACTIVE: information indicating whether a second resume procedure is supported. It may indicate whether the second resume procedure is supported for each frequency band supported by the terminal. When the terminal supports n frequency bands, n pieces of 1-bit information are reported.

[0048] 3. Various capability information related to data transmission / reception between the terminal and the base station (e.g., whether specific decoding is supported, etc.).

[0049] A terminal that supports RRC_INACTIVE supports the first resume procedure on all frequency bands supported by the terminal. That is, the first information related to RRC_INACTIVE support is information applied to multiple frequency bands, and the second information related to RRC_INACTIVE is information applied to one frequency band. A terminal that does not support RRC_INACTIVE does not support the second resume procedure on any frequency band it supports. The serving base station provides appropriate NR configuration information to the UE with reference to the capabilities of the UE. The UE and the serving base station transmit and receive data in the RRC_CONNECTED state, and when data transmission and reception are completed, the serving base station determines to transition the terminal state to the RRC_INACTIVE state.

[0050] In step 2a-13, the first base station transmits an RRCRelease message to the terminal. The RRCRelease message includes a SuspendConfig IE, and the SuspendConfig includes the following information.

[0051] <suspendconfig> 1. First Terminal Identifier: The identifier of the terminal that may be included in the ResumeRequest when the state transitions to RRC_CONNECTED. It is 40 bits long.

[0052] 2. Second Terminal Identifier: The identifier of the terminal that may be included in the recovery request when the state transitions to RRC_CONNECTED. It is 24 bits long.

[0053] 3. ran-Paging Cycle: The paging cycle applied in the RRC_INACTIVE state.

[0054] 4. ran-Notification AreaInfo: Configuration information for the ran-Notification Area, which consists of a list of cells, etc. When the ran-Notification Area changes, the terminal initiates a recovery process.

[0055] 5. t380: A timer associated with the periodic recovery process.

[0056] 6. NextHopChangingCount (NCC): A counter used to export a new security key after the recovery process is performed.

[0057] 7. Information related to the second recovery process: DRB list configured with the second recovery process, 1 bit information indicating whether the second recovery process is configured for SRB2, 1 bit information indicating whether the second recovery process is configured for SRB4, data size threshold for the second recovery process (hereinafter referred to as the dedicated data threshold), and reference signal received power threshold for the second recovery process (hereinafter referred to as the dedicated reference signal received power threshold). Since SRB1, one of SRB1, SRB2, SRB3, and SRB4, sends and receives the most important RRC control messages, it is important to quickly send RRC control messages via the second recovery procedure, and the second recovery procedure is very effective for SRB1. SRB2 and SRB4 are less important than SRB1 because they may generate relatively large messages, but they still transmit important control messages, so the second recovery procedure is also effective for SRB2 and SRB4. SRB3 is not used when no multiple connections are established. Therefore, in this invention, the second recovery procedure can be explicitly configured for SRB2 and SRB4. The second recovery procedure is not explicitly configured for SRB1 and SRB3. The second recovery procedure is implicitly configured for SRB1 if at least one radio bearer is configured with the second recovery procedure. In any case, the second recovery procedure is not configured for SRB3.

[0058] In step 2a-14, the terminal executes the SuspendConfig operation set. The SuspendConfig operation set is applied at a predetermined first time point or second time point. When the SuspendConfig operation is executed, the following operations are performed in sequence.

[0059] <SuspendConfig operation set> 1. Apply suspendConfig.

[0060] 2. Reconfigure the MAC.

[0061] 3. Reconfigure the RLC entity of SRB1.

[0062] 4. All SRBs and DRBs are suspended.

[0063] 5. Start T380 which is configured as t380.

[0064] 6. Enter the RRC_INACTIVE state.

[0065] When the second resume related information is included, the terminal applies the first time point for the SuspendConfig operation set; if the second resume related information is not included, the terminal applies the second time point.

[0066] The first time point is as follows.

[0067] The earlier time point between the time point 100ms after receiving the RRCRelease message and the time point at which the lower layer successfully acknowledges the reception of the RRCRelease message.

[0068] The second time point is as follows.

[0069] The earlier time point between the time point 60ms after receiving the RRCRelease message and the time point at which the lower layer successfully acknowledges the reception of the RRCRelease message.

[0070] The reason for using different time points is that the reliability of the RRCRelease message including the second resume related information should be higher than the reliability of the RRCRelease message not including the second resume information.

[0071] In step 2a-15, the terminal moves to a new cell. The terminal may compare the radio signal quality of the serving cell and neighboring cells to reselect a neighboring cell with better radio signal quality. Alternatively, a cell whose radio signal quality is greater than or equal to a specific threshold may be selected.

[0072] In steps 2a-17, the terminal receives system information including SIB1 in the new cell. SIB1 may include at least two of the following types of information.

[0073] <sib1> 1. t319 value 2. A 1-bit message indicating whether the second recovery process is allowed (or whether the second recovery process is configured or available).

[0074] If a second recovery process is allowed, the following information is included in the system information (hereinafter, SIBX) in addition to SIB1 and is broadcast.

[0075] <sibx> 1. Data size threshold for the second recovery process (hereinafter referred to as the common data threshold) 2. The reference signal received power threshold for the second recovery process (hereinafter referred to as the common reference signal received power threshold). 3. Random access transport resource information used in the second recovery process.

[0076] 4. t319ext If at least one radio bearer is configured with a second recovery procedure, that is, if at least one DRB is configured with a second recovery procedure or if SRB2 or SRB4 is configured with a second recovery procedure, the terminal receives SIBX.

[0077] The terminal that receives the necessary system information, including SIB1, performs the RRC_INACTIVE operation shown in Table 4 in the cell.

[0078] In steps 2a-19, an event triggering the recovery process occurs. The recovery process can be triggered when an upper layer or AS requests the resumption of a suspended RRC connection or when new data appears.

[0079] In steps 2a-21, the terminal triggers one of the first recovery process and the second recovery process. If any one of the first recovery conditions is met, the first recovery process is triggered.

[0080] <First Set of Recovery Conditions> 1. The upper layer requests to resume the suspended RRC connection.

[0081] 2. Received a RAN paging message including the first identifier.

[0082] 3. RNA renewal occurs.

[0083] 4. Data has been generated in the radio bearer that is allowed to trigger the second recovery process, but does not meet at least one of the second recovery conditions.

[0084] If all conditions in the second recovery set are met, the second recovery process is triggered.

[0085] <Second set of recovery conditions> 1. Generate data that can be transmitted in the bearers belonging to the first bearer set.

[0086] 2. The amount of data available for transmission for the bearers belonging to the first bearer set is less than the final data threshold.

[0087] 3. The reference signal received power of the current serving cell is higher than the final reference signal received power threshold.

[0088] 4. The current serving cell provides transmission resources for the second recovery process.

[0089] A radio bearer that allows triggering (or permits) a second recovery process means both the DRB and the SRB that permit the second recovery process. SRB3 does not permit the second recovery process, while SRB2 and SRB4 are indicated by explicit information as to whether the second recovery process is permitted. When a second recovery process is permitted in at least one radio bearer, it is automatically permitted in SRB1.

[0090] The final data threshold is the lower of the dedicated data threshold and the common data threshold. Alternatively, if both dedicated and common data thresholds exist, the final data threshold is the dedicated data threshold. If only one exists, that is the final data threshold. Alternatively, if both dedicated and common data thresholds exist, the common data threshold is the final data threshold; if only one exists, that is the final data threshold.

[0091] The final reference signal received power threshold is the higher of the dedicated reference signal received power threshold and the common reference signal received power threshold. Alternatively, if both a dedicated reference signal received power threshold and a common reference signal received power threshold exist, the final reference signal received power threshold is the dedicated reference signal received power threshold. If only one exists, that is the final reference signal received power threshold. Alternatively, if both a dedicated reference signal received power threshold and a common reference signal received power threshold exist, the common reference signal received power threshold is the final reference signal received power threshold; if only one exists, that is the final reference signal received power threshold.

[0092] When at least one of the first conditions is met and all of the second conditions are met, that is, when both the first and second recovery processes are triggered, the terminal selects the second recovery process.

[0093] In steps 2a-23, the terminal and the base station perform the first recovery process or the second recovery process.

[0094] Figure 2b This is a diagram illustrating the first recovery process and the second recovery process according to an embodiment of the present invention.

[0095] The first recovery process is as follows.

[0096] In step 2b-11, the terminal executes the first recovery operation set 1. The first recovery operation set 1 is the operation performed when the first recovery process starts, as follows. By executing the first operation set 1, the terminal can receive downlink control messages from the base station via SRB1.

[0097] <First Recovery Operation Set 1> 1. Apply the default SRB1 configuration.

[0098] 2. Apply the default MAC cell group configuration 3. Start T319 which is set to t319 received from SIB1.

[0099] The default SRB1 configuration is as follows.

[0100] The default MAC cell group configuration is as follows.

[0101] T319 set to t319 is a timer for performing subsequent measures (e.g., transitioning to RRC_IDLE, etc.) when the first recovery procedure fails. When RRCResume is received, T319 set to t319 stops. If RRCResume is not received until T319 set to t319 expires, the terminal executes the T319 expiration action set.

[0102] <T319 Expiration Action Set> 1. Reconfigure MAC.

[0103] 2. Discard the UE Inactive AS Context.

[0104] 3. Release suspendConfig.

[0105] 4. Discard the security key.

[0106] 5. Release all RLC entities, PDCP entities and SDAP entities.

[0107] 6. Transition to RRC_IDLE and perform a cell selection operation.

[0108] In step 2b-13, the terminal executes the first recovery procedure action set 2. The first recovery procedure action set 2 is an operation performed before sending ResumeRequest.

[0109] <First Recovery Procedure Action Set 2> 0. Restore the RRC configurations of the UE Inactive AS Context except for masterCellGroup and PDCP-config.

[0110] 1. ResumeMAC-I Calculation: Calculate the 16-bit message verification code using the first security key (the security key used in the RRC_CONNECTED state or the security key used when receiving RRC Release).

[0111] 2. Use NCC to export the second base station security key. From the second base station security key, export the second security key, the third security key, the fourth security key, and the fifth security key.

[0112] 3. All radio bearers except SRB0 are configured to use a second and a third security key or a fourth and a fifth security key.

[0113] 3. Reset the PDCP entity of SRB1.

[0114] 4. Restore SRB1.

[0115] In steps 2b-15, the terminal sends a ResumeRequest message to the second base station. The MAC PDU containing the ResumeRequest message does not include data from other radio bearers. The ResumeRequest contains the following information.

[0116] <resumerequest> 1. First identifier or second identifier: including the identifier indicated in the system information, which is either the first identifier or the second identifier given in SuspendConfig.

[0117] 2. ResumeMAC-I: A 16-bit message verification code used to ensure the integrity of the ResumeRequest message. The terminal calculates resumeMAC-I using the previously used security key (either the security key used in the RRC_CONNECTED state or the security key used when receiving RRCRelease).

[0118] 3. resumeCause: indicates one of emergency, highPriorityAccess, mt-Access, mo-Signalling, mo-Data, mo-VoiceCall, mo-VideoCall, mo-SMS, rna-Update, mps-PriorityAccess, mcs-PriorityAccess and smallDataTransfer The terminal performing the first recovery process selects one of the remaining values ​​other than smallDataTransfer as the resumeCause. This is so that the base station can determine whether to perform the second recovery process based on the resumeCause.

[0119] In step 2b-17, the terminal receives RRCResume. RRCResume contains the following information.

[0120] <rrcresume> 1. MasterCellGroup: The CellGroupConfig used for masterCellGroup includes RLC bearer information, MAC configuration information, PHY configuration information, and SpCell configuration information.

[0121] 2. RadioBearerConfig: This is the radio bearer configuration information, including SRB configuration information and DRB configuration information.

[0122] In step 2b-19, the terminal executes the first recovery process operation set 3.

[0123] <First Recovery Process Operation Set 3> 1. Stop T319.

[0124] 2: Stop T380.

[0125] 3: Restore and apply the masterCellGroup of the UE Inactive AS Context 4: Apply CellGroupConfig and radioBearerConfig in RRCResume 5. Restore SRB2, SRB3 and all DRBs.

[0126] 6. Transition to the RRC_CONNECTED state.

[0127] 7. Stop the cell reselection process.

[0128] In steps 2b-21, the terminal sends an RRRCResumeComplete message to the second base station. This RRRCResumeComplete message contains the PLMN identifier information selected by the terminal.

[0129] In steps 2b-23, the terminal sends and receives data with the second base station. In this case, the terminal can send a MAC CE, such as a BSR or PHR, to the base station. When the BSR trigger condition is met, the terminal multiplexes the BSR in the uplink MAC PDU and sends the MAC PDU. When the PHR trigger condition is met, the terminal multiplexes the PHR MAC CE in the uplink MAC PDU and sends the MAC PDU. BSR trigger conditions include the arrival of new data with high priority and the expiration of a periodic timer. PHR trigger conditions include changes in the reference signal received power exceeding a predefined threshold, the activation of a new auxiliary cell, etc.

[0130] In steps 2b-25, when data transmission / reception with the terminal is completed, the second base station sends an RRCRelease including SuspendConfig to the terminal to switch the terminal to the RRC_INACTIVE state.

[0131] In steps 2b-27, the terminal that receives the RRRCRelease message including SuspendConfig starts the T380.

[0132] The second recovery process is as follows.

[0133] In steps 2b-31, the terminal executes the second recovery operation set 1. The second recovery operation set 1 is the operation taken when the second recovery process is triggered, specifically as follows: By executing the second recovery operation set 1, the terminal can receive downlink control messages from the base station via SRB1, send uplink data on radio bearers that allow the second recovery process (or can transmit data in the INACTIVE state, or are configured for the second recovery process), and receive downlink data.

[0134] <Second Recovery Operation Set 1> 0: Restore all RRC configurations of the UE Inactive AS Context (including radio bearer settings for the first bearer set, masterCellGroup, and PDCP-config).

[0135] 1. Boot the T319ext configured as t319ext. 2. Stop T380 3. ResumeMAC-I calculation: Calculate the 16-bit MAC-I using the previous K_RRCint, i.e., the first security key (K_RRCint used in the previous RRC_CONNECTED state or K_RRCint used when receiving RRCLease).

[0136] 4. Use the first base station security key and NCC to derive the second base station security key. From the second base station security key, derive the second security key, third security key, fourth security key, and fifth security key.

[0137] 5. Configure the first bearer set to apply the second and third security keys or the fourth and fifth security keys.

[0138] 6. Reset the PDCP entity of the first bearer set.

[0139] 7. Restore the radio bearers of the first bearer set.

[0140] 8. Stop the cell reselection process.

[0141] 9. Start the second cell reselection procedure.

[0142] T319ext, which is set to t319ext, is a timer for performing subsequent measures when the second recovery procedure fails, for example, transitioning to RRC_IDLE. T319, T319ext and T380 have the following characteristics.

[0143] In the first recovery procedure, T380 and T319 are stopped after receiving the RRCResume message and before configuring cell group information, so as to prevent unnecessary subsequent operations caused by timer expiry by stopping the timers as a first operation after receiving the RRCResume message.

[0144] In the first recovery procedure, starting T319 between the time point when the default SRB1 configuration is applied and the time point when SRB1 is recovered is to start T319 as close as possible to the time point when SRB1 becomes available.

[0145] In the second recovery procedure, starting T319ext between the time point when the SRB1 configuration stored in the UE Inactive AS Context is applied and the time point when SRB1 is recovered is to start T319ext as close as possible to the time point when SRB1 becomes available.

[0146] In the second recovery procedure, starting T380 between the time point when the SRB1 configuration stored in the UE Inactive AS Context is applied and the time point when SRB1 is recovered is to start T380 as close as possible to the time point when T319ext is started, so as to reduce the processing load for timer processing in the UE.

[0147] The time point at which the SRB1 configuration stored in the UE Inactive AS Context is applied is the same as the time point at which the radio bearer configuration of the first bearer set stored in the UE Inactive AS Context is applied.

[0148] If the RRCResume is not received until T319ext, which is set to t319ext, expires, the terminal may execute the T319ext expiry operation set or the T319 expiry operation set. The base station may configure in SuspendConfig or in system information which one to select between the T319ext expiry operation set and the T319 expiry operation set.

[0149] <T319ext Expiry Operation Set> 1. Reset MAC 2. Maintain UE Inactive AS Context 3. Keep suspendConfig 4. Discard the first base station security key and the first security key in the UE, and store the second base station security key and the third security key. 5. Suspend all SRBs and DRBs 6. Start the T380 configured as t380. 7. Stop the second cell reselection process. 8. Initiate the cell reselection process 9. After selecting a suitable cell, perform RNA update. The first bearer set is a collection of radio bearers explicitly or implicitly configured with the second recovery process, consisting of SRB1 and radio bearers associated with the second recovery process. Radio bearers associated with the second recovery process refer to radio bearers that explicitly allow the second recovery process or radio bearers that are explicitly configured with the second recovery process.

[0150] Stopping the cell reselection process means stopping the existing cell reselection process that was executed before the second recovery process began.

[0151] In the existing cell reselection process, the UE prioritizes the frequency to be reserved by considering the cell reselection priority provided by the base station, ranks each cell of the selected frequency by considering the reference signal received power and various offsets, and reselects the cell with the highest ranking.

[0152] When the second cell reselection process begins, the terminal stops using the cell reselection priority and offset indicated by the base station and uses the following parameters.

[0153] <Second Community Re-election Process> 1. Increase the cell reselection priority of the current service frequency to the highest priority.

[0154] 2. Increase the first Qhyst by a predetermined value. Or apply the second Qhyst.

[0155] When the terminal determines the cell order, it uses Qhyst to weight the current serving cell. That is, the order is determined by adding the Qhyst to the reference signal received power of the current serving cell. The first Qhyst is included in SIB2 and broadcast. The second Qhyst, or a predetermined value, is included in SIBX and broadcast.

[0156] In step 2b-33, the terminal transmits to the second base station a MAC PDU that includes a first SDU with a ResumeRequest message and data of a first bearer set (or data of a bearer configured with a second resume procedure). A terminal performing the second resume procedure selects smallDataTransfer as the ResumeCause. The terminal may include a priority-based BSR MAC CE and a PHR MAC CE in the MAC PDU. If a BSR / PHR inclusion condition is satisfied and a BSR / PHR cancellation condition is not satisfied, the terminal includes and transmits the priority-based BSR MAC CE and PHR MAC CE in the MAC PDU. Even if the BSR / PHR inclusion condition is satisfied, when the BSR / PHR cancellation condition is satisfied, the terminal transmits a MAC PDU that does not include the priority-based BSR and PHR.

[0157] <BSR / PHR inclusion condition> After transmitting the MAC PDU including the ResumeRequest (or the first uplink MAC PDU of the second resume procedure), there is more data to be transmitted, or the uplink grant for transmitting the MAC PDU including the ResumeRequest (or the first uplink grant of the second resume procedure) cannot accommodate all pending data available for transmission.

[0158] <BSR / PHR cancellation condition> If at least one of the corresponding subheader of the triggered BSR or the corresponding subheader of the triggered PHR is not included in the MAC PDU containing the ResumeRequest, the uplink grant for transmitting the MAC PDU (or the first uplink grant of the second resume procedure) can accommodate all pending data available for transmission, but if both the corresponding subheader of the triggered BSR and the corresponding subheader of the triggered PHR are included in the MAC PDU, the MAC PDU cannot accommodate all pending data available for transmission.

[0159] In step 2b-35, the terminal and the base station transmit and receive data of the first bearer set. The data of the first bearer set is scheduled by C-RNTI, and the terminal monitors the frequency region and time interval indicated in SIBX for transmitting and receiving a small amount of data (or for transmitting and receiving data in the second resume procedure).

[0160] When the data transmission is completed, the base station determines to terminate the second resume procedure.

[0161] In steps 2b-37, the second base station sends an RRCRelease containing SuspendConfig to the terminal to terminate the second recovery process. Upon receiving the RRCRelease containing SuspendConfig, the terminal executes the second recovery process operation set 2 to terminate the second recovery process.

[0162] <Second Recovery Operation Settings 2> 1. Stop monitoring the frequency range and time interval indicated in SIBX for small data transmissions. 2. Reset the MAC address 3. Update suspendConfig 4. Discard the first base station security key and the first security key in the UE, and store the second base station security key and the third security key. 5. Suspend all SRBs and DRBs except SRB0. 6. Startup is set to T380. 7. Stop the second cell reselection process. 8. Initiate the cell reselection process Figure 2c This is a diagram showing the structure of the uplink MAC PDU used in the second recovery process.

[0163] The MAC SDU (first SDU) (2c-15) including the ResumeRequest message precedes the MAC PDU (2c-11), and the MAC SDU (second SDU) (2c-19) including the data of the first bearer set (data of the bearer configured for the second recovery process) follows the MAC PDU. This is to enable the base station receiving the MAC PDU to quickly identify that the MAC PDU is related to the second recovery process. The first SDU includes a portion of the MAC-I calculated by the first security key (the previously used K_RRCint), and the second SDU includes the MAC-I calculated by the fifth security key (a new K_UPenc derived from the second base station security key). The MAC subheader 2c-13 of the first SDU includes two R bits and an LCID field, and the MAC subheader 2c-17 of the second SDU includes one R bit, an F field, an LCID field, and an L field. The LCID field indicates which logical channel the corresponding MAC SDU belongs to or which MAC CE the corresponding MAC CE is, and the L field indicates how many bytes the corresponding MAC SDU or MAC CE is. A MAC SDU or MAC CE and its corresponding MAC subheader are called a MAC subPDU. Figure 2c The MAC PDU 2c-11 shown includes two MAC sub-PDUs, 2c-21 and 2c-23. Below, we will... Figure 2c The structure of the MAC PDU shown is called MAC PDU Structure 1. MAC PDU Structure 1 is characterized in that the MAC sub-PDU, which includes the MAC SDU and has an R / LCID sub-header, precedes the MAC sub-PDU, which includes the MACSDU and has an R / F / LCID / F header. This feature allows the base station to process the ResumeRequest message as quickly as possible, as described above.

[0164] Figure 2d This is a diagram illustrating the structure of a typical uplink MAC PDU. Although a MAC PDU with two MAC sub-PDUs is illustrated, a MAC PDU can include two or more MAC sub-PDUs. The following will... Figure 2d The structure of the MAC PDU shown is called MAC PDU Structure 2. In MAC PDU Structure 2, the MAC sub-PDU with the R / LCID subheader is located after the MAC sub-PDU with the R / F / LCID / F subheader and including the MAC SDU. The MAC sub-PDU with the R / LCID subheader corresponds to the MAC CE in most cases, and by placing the MAC sub-PDU including the MAC CE after the MAC sub-PDU including the MAC SDU, the terminal can preprocess the MAC sub-PDU including the MAC SDU before receiving the uplink grant.

[0165] The first SDU 2c-15 is the first RRC control message received by the base station. Therefore, the base station and the terminal need to process the first SDU using the same configuration without prior negotiation. On the other hand, the second SDU 2c-20 can be processed after the base station processes the first SDU, and can be processed after the base station restores the UE Inactive AS Context. Therefore, the second SDU can be processed according to the configuration stored in the UE Inactive AS Context.

[0166] In this invention, a first configuration is applied to a first SDU, and a second configuration is applied to a second SDU. The first configuration refers to a pre-defined configuration in the standard (or a configuration standardized to a single value), and the second configuration refers to a configuration stored in the UE Inactive ASContext. Typically, a MAC PDU includes only a MAC SDU applying the first configuration or only a MAC SDU applying the second configuration; however, in this invention, the MAC SDU applying the first configuration and the MAC SDU applying the second configuration are transmitted together in a single MAC PDU. This is to enable faster transmission of the MAC SDU applying the second configuration.

[0167] The first and second configurations can include at least PDCP configuration, RLC configuration, and logical channel configuration. The first configuration sets PDCP to unused, RLC to RLCTM, and logical channel to highest priority, LCG ID 0, LCID 0, etc. Alternatively, the first configuration can be the default SRB1 configuration.

[0168] The second configuration of the bearer configured for the second recovery process is as follows: The PDCP configuration is the PDCP configuration of the corresponding bearer stored in the UE Inactive ASContext; the RLC configuration is the RLC configuration (e.g., various timer values) of the RLC bearer associated with the corresponding bearer stored in the UE Inactive ASContext; and the logical channel configuration is the logical channel configuration of the RLC bearer. The terminal applies the configurations stored in the UE Inactive ASContext as is to the PDCP and RLC configurations. The terminal applies only some of the configurations stored in the UE Inactive ASContext to the logical channel configurations and does not apply the remaining configurations as if they were not configured. The logical channel configuration of the radio bearers belonging to the first bearer set consists of LCID, LCG ID, priority, and various restriction-related configurations. When transmitting data of the first bearer set during the second recovery process, the terminal uses the stored values ​​and processes various restriction-related configurations as if they were not configured. Various restriction-related configurations include, for example, allowedServingCells, allowedSCS-List, and maxPUSCH-Duration. If the restriction-related configuration is not configured, the terminal determines that there are no restrictions when sending and receiving data on the corresponding logical channel. The stored restriction-related configuration can be applied when the first recovery procedure is initiated.

[0169] When the first SDU 2c-15 and the second SDU 2c-19 are multiplexed in a single MAC PDU during the second recovery process, the terminal applies a predefined configuration to the first SDU: PDCP not used, RLC TM, highest priority, LCID 0, and LCGID 0. The terminal applies the overall PDCP configuration, the overall RLC configuration of the corresponding bearer, and a portion of the logical channel configuration of the corresponding bearer's RLC bearer stored in the UE Inactive AS Context to the second SDU, but does not apply the remaining logical channel configurations of the corresponding bearer's RLC bearer. The applied logical channel configurations can be LCID, priority, and LCG ID, and the unapplied logical channel configurations can be allowedServingCells, allowedSCS-List, maxPUSCH-Duration, etc.

[0170] The terminal generates SDU1 by applying the first configuration and generates SDU2 by applying the second configuration.

[0171] An uplink MAC PDU can include a MAC SDU or a MAC CE. A MAC CE refers to control information generated and transmitted by the MAC layer, such as a BSR or PHR. MAC CEs can have a fixed or variable size. The L field is not used in the MAC subheader of a fixed-size MAC CE. A typical MAC SDU has a variable size, and the L field is used in the corresponding subheader. A MAC sub-PDU including a MAC CE always follows a MAC sub-PDU including a MAC SDU. Therefore, in a typical uplink MAC PDU that multiplexes at least two MAC sub-PDUs, the MAC sub-PDU with the L field comes first, and the MAC sub-PDU without the L field comes last. Generally, all MAC SDUs included in an uplink MAC PDU are protected by a security key derived from the same base station security key.

[0172] Figure 2e This is a diagram illustrating the hierarchical structure of the security key.

[0173] Terminals and base stations use security keys derived from KgNB 2e-11 to perform integrity protection and encryption. Four sub-security keys, K_UPenc 2e-21, K_UPint 2e-23, K_RRCenc 2e-25, and K_RRCint 2e-27, are derived from KgNB2e-11. During handover or recovery procedures, KgNB derives KgNB* 2e-33 by inputting NCC 2e-31, and also derives new sub-security keys from KgNB*.

[0174] exist Figure 2c In this process, the first SDU 2c-15 is protected by the integrity of K_RRCint derived from the KgNB used in the previous cell. That is, at least a part of the MAC-I calculated by K_RRCint is included in the first SDU and sent together. The second SDU 2c-19 is protected by the integrity of K_UPint and is encrypted by K_UPenc in the sub-security key of KgNB* derived from the KgNB and NCC used in the previous cell.

[0175] In other words, during the second recovery process, some MAC SDUs included in one MAC PDU are protected by a security key derived from KgNB, and another MAC SDU is protected by a security key derived from KgNB*.

[0176] exist Figure 2d The MAC SDU multiplexed in the MAC PDU 2d-11 is encrypted or protected for integrity by a sub-security key derived from one of KgNB and KgNB*.

[0177] The KgNB previously used or used when receiving RCRelease is the first base station security key. K_RRCint, derived from the first base station security key, is the first security key. KgNB* (or KgNB derived from the first base station security key and NCC, or from the second recovery procedure operation set 1) is the second base station security key. K_RRCenc, K_RRCint, K_UPenc, and K_UPint, derived from the second security key, are referred to as the second security key, third security key, fourth security key, and fifth security key, respectively.

[0178] Traditionally, a MAC PDU is encrypted or protected for integrity using a security key derived from a base station security key. In this invention, by multiplexing MAC SDUs protected by security keys from different base station security keys into a single MAC PDU, MAC SDUs can be sent much faster.

[0179] Figure 2h This is a diagram illustrating the MAC-I calculation and encryption process.

[0180] The sending end generates MAC-I at 2h-01 and sends it to the receiving end at 2h-02. The sending end generates MAC-I 2h-23 by inputting the security key 2h-19, COUNT 2h-11, MESSAGE 2h-13, DIRECTION 2h-15, and BEARER 2h-17 into NIA (NR Integrity Algorithm) 2h-21, and sends the generated MAC-I 2h-23 to the receiving end.

[0181] The receiver also calculates XMAC-I 2h-25 by inputting the security key 2h-19, COUNT 2h-11, MESSAGE 2h-13, DIRECTION 2h-15, and BEARER 2h-15 into the NR Integrity Algorithm (NIA) 2h-21, and determines that the received MAC-I is the same. MAC-I and XMAC-I can only be the same if the sender and receiver use the same NR Integrity Algorithm (NIA) 2h-21, the same security key 2h-19, the same COUNT 2h-11, the same MESSAGE 2h-19, the same DIRECTION 2h-15, and the same BEARER 2h-17. MAC-I has a 32-bit size. The MAC-I included in the first SDU 2c-15 of the uplink MAC PDU 2c-11 of the second recovery process is the last 16 bits of the MAC-I calculated using the first security key, a COUNT set to all zeros, a DIRECTION set to zeros, and a message consisting of the terminal identifier and the cell identifier.

[0182] The MAC-I included in the second SDU 2c-19 of the uplink MAC PDU 2c-11 of the second recovery process is for the PDCP SDU belonging to the first bearer set and is calculated using the fifth security key, the COUNT of the PDCP SDU, the DIRECTION set to 0, and the DRB identifier and the message as the PDCP SDU.

[0183] The sender (2h-31) processes the plaintext into an encrypted block and sends it to the receiver (2h-32). The sender generates a keystream block (2h-53) by inputting the security keys (2h-49, COUNT 2h-41, BEARER 2h-43, DIRECTION 2h-45, and LENGTH 2h-47) into the NR encryption algorithm NEA (2h-51). The sender then performs a specific XOR operation on the generated keystream block containing the plaintext (2h-33) to generate the encrypted block (2h-35) and sends it to the receiver. LENGTH is the length of the plaintext.

[0184] The receiving end uses the same input and the same security key to reverse-convert the received encrypted block into plain text.

[0185] The second SDU 2c-19 of the uplink MAC PDU 2c-11 in the second recovery process may include an encrypted PDCP SDU of the first bearer set. The PDCP SDU is encrypted using a fourth security key, the COUNT of the PDCP SDU, the DIRECTION set to 0, the DRB identifier BEARER, and the PDCP SDU length LENGTH.

[0186] Figure 2f This is a diagram showing the structure of the first BSR MAC CE and the second BSR MAC CE, which are BSRs based on logical channel groups.

[0187] The first BSR MAC CE includes a logical channel group identifier field 2f-01 and a first buffer size field 2f-03. The logical channel group identifier field 2f-01 is 3 bits in size and indicates one of the logical channel group identifiers between 0 and 7. The first buffer size field 2f-03 is 5 bits in size and indicates one of the first buffer size indices between 0 and 31. A first buffer size index of 0 means that there is no data available for transmission in the logical channels belonging to the corresponding logical channel group. A first buffer size index of 31 means that the total amount of data available for transmission in the logical channels belonging to the corresponding logical channel group is greater than the 30th first buffer size. A first buffer size index of 1 means that the total amount of data available for transmission in the logical channels belonging to the corresponding logical channel group is greater than 0 and less than or equal to the first first buffer size. A first buffer size index n (2 <= n <= 30) indicates that the total amount of data available for transmission in the logical channels belonging to the corresponding logical channel group is greater than or equal to the (n-1)th first buffer size and less than or equal to the nth first buffer size. The standard defines the first 30 buffer sizes.

[0188] The second BSR MAC CE includes eight LCGi bits 2f-11 and multiple second buffer size fields 2f-13. The LCGi bits indicate whether a second buffer size field exists for logical channel group i. For example, LCG1 indicates whether a second buffer size field exists for logical channel group 1. If this field is 1, the corresponding LCG has a second buffer size field. The second buffer size field has an 8-bit size and indicates one of the second buffer size indices between 0 and 255. Second buffer size index 0 indicates that there is no data available for transmission in the logical channels belonging to the corresponding logical channel group. Second buffer size index 254 means that the total amount of data available for transmission in the logical channels belonging to the corresponding logical channel group is greater than the 253rd second buffer size. Second buffer size index 1 means that the total amount of data available for transmission in the logical channels belonging to the corresponding logical channel group is greater than 0 and less than or equal to the first second buffer size. Second buffer size index n (2 <= n <= 253) indicates that the total amount of data available for transmission in the logical channels belonging to the corresponding logical channel group is greater than or equal to the (n-1)th second buffer size and less than or equal to the nth second buffer size. Second buffer size index 255 is not used. The standard defines a second buffer size of 252.

[0189] Configure logical channel groups when configuring logical channels. Logical channels and logical channel groups are configured by RRC control messages.

[0190] Figure 2g This diagram illustrates the structure of the third and fourth BSR MAC CEs as priority-based BSRs. The third BSR MAC CE includes a priority identifier field 2g-01 and a third buffer size field 2g-03. The priority identifier field is 4 bits in size. It indicates a value between 0 and 15, corresponding one-to-one with a logical channel priority between 1 and 16. That is, the value of the priority identifier field plus 1 equals the actual priority. For example, priority identifier field 0000 represents priority 1, 0001 represents priority 2, and 1111 represents priority 16. The third buffer size field indicates a third buffer size index between 0 and 15, which is 4 bits in size. Unlike the first or second buffer size index 0, the third buffer size index 0 means that the sum of data available for transmission on the logical channel with the corresponding priority is equal to or greater than 0 and less than the first third buffer size index. A third buffer size index n (2 <= n <= 14) indicates that the total amount of data that can be transmitted by a logical channel of the corresponding priority is greater than or equal to the (n-1)th third buffer size and less than or equal to the nth third buffer size. A third buffer size index of 15 means that the total amount of data that can be transmitted by a logical channel of the corresponding priority is greater than the 15th third buffer size. The first, second, and third buffer sizes are predefined in the specification. The standard defines 15 third buffer sizes.

[0191] The fourth BSR MAC CE includes PGi bits and multiple second buffer size fields.

[0192] PGi indicates the presence of the second buffer size field of the priority group identifier i. A priority group consists of at least one priority, and eight groups from priority group 0 to priority group 7 can be configured within a cell. The priority of each logical channel is configured by a predetermined RRC control message received from the first NR cell, and the mapping between priorities and priority groups is configured by predetermined system information received from the second NR cell. The system information can be SIBX. For example, a list of priorities mapped for each priority group can be broadcast via SIBX.

[0193] Figure 3 This is a flowchart illustrating the operation of the terminal.

[0194] In step 3a-01, the UE receives a first downlink control message in the first NR cell, which includes a first timer value and indicates a transition to the RRC_INACTIVE state.

[0195] In step 3a-03, the UE suspends all radio bearers except signaling radio bearer 0 and starts the first timer.

[0196] In step 3a-05, the UE performs cell selection in the first NR cell and pre-occupies the second NR cell.

[0197] In step 3a-07, the UE receives system information from the second NR cell, including information related to the second recovery process, a second timer value, and a third timer value.

[0198] In step 3a-09, the UE initiates a first recovery process or a second recovery process based on the recovery process conditions.

[0199] In steps 3a-11, the UE applies a predetermined configuration to signaling radio bearer 1 and restores signaling radio bearer 1. In the case of a first restoration process, the predetermined configuration may be the default configuration. In the case of a second restoration process, the predetermined configuration may be the configuration stored in the UE Inactive AS Context.

[0200] In steps 3a-13, the terminal sends a first uplink control message, which includes the terminal's identifier and the reason for recovery. In the case of a first recovery process, only the first uplink control message is sent, while in the case of a second recovery process, the first uplink control message is sent together with the data of the first bearer.

[0201] In steps 3a-15, the terminal receives a second downlink control message including cell group configuration information. The UE applies the cell group configuration information and transitions to the RRC_CONNECTED state to continue data transmission and reception. In the case of the second recovery process, data transmission / reception is typically completed without receiving the second downlink control message; however, when predetermined conditions are met, the second recovery process can be switched to the first recovery process. The base station sends the second downlink control message to the terminal performing the second recovery process.

[0202] In the above steps, the terminal controls the first timer, the second timer, and the third timer as follows.

[0203] If the first recovery process begins, the UE starts a second timer after applying the default signaling radio bearer 1 configuration in step 3a-11 and before restoring signaling radio bearer 1. When the second downlink control message is received in step 3a-15, the UE stops the first and second timers before applying cell group configuration information.

[0204] If the second recovery process begins, after the UE applies the signaling radio bearer 1 configuration stored in the UE Inactive ASContext in step 3a-11, it stops the first timer and starts the third timer before restoring signaling radio bearer 1. When the second downlink control message is received in step 3a-15, the UE stops the third timer before applying the cell group configuration information.

[0205] The UE also discards the UE Inactive AS Context when the second timer expires, performs cell selection, transitions to the RRC_IDLE state, stores the UE Inactive AS Context when the third timer expires, suspends all radio bearers except signaling radio bearer 0, and starts the first timer.

[0206] Furthermore, when the first timer expires after the second process is initiated, the UE first determines whether the second process is in progress. If the second process is not in progress, the RNA update process is initiated. On the other hand, if the first timer expires after the first process is initiated, the RNA update process is started regardless of whether the first process has been executed.

[0207] The terminal also initiates an RNA update process in the current cell when the first timer expires, and selects a suitable cell and then starts the RNA update process when the third timer expires.

[0208] Figure 4a This is a block diagram illustrating the internal structure of a UE that applies this disclosure.

[0209] Referring to the figure, the UE includes a controller 4a-01, a storage unit 4a-02, a transceiver 4a-03, a main processor 4a-04, and an I / O unit 4a-05.

[0210] Controller 4a-01 controls the overall operation of the UE in mobile communication. For example, controller 4a-01 receives / transmits signals via transceiver 4a-03. Additionally, controller 4a-01 records and retrieves data in storage unit 4a-02. For this purpose, controller 4a-01 includes at least one processor. For example, controller 4a-01 may include a communication processor (CP) that performs communication control and an application processor (AP) that controls upper layers (such as applications). The controller controls the storage unit and the transceiver, enabling the execution of… Figure 3 The UE operation shown is illustrated.

[0211] Storage unit 4a-02 stores data used for UE operation, such as basic programs, application programs, and configuration information. Storage unit 4a-02 provides the stored data according to requests from controller 4a-01.

[0212] The transceiver 4a-03 consists of an RF processor, a baseband processor, and multiple antennas. The RF processor performs functions such as transmitting / receiving signals over the wireless channel, including signal band conversion and amplification. Specifically, the RF processor up-converts the baseband signal provided by the baseband processor into an RF band signal, transmits this signal through the antennas, and down-converts the RF band signal received through the antennas back into a baseband signal. The RF processor may include transmit filters, receive filters, amplifiers, mixers, oscillators, digital-to-analog converters (DACs), analog-to-digital converters (ADCs), etc. The RF processor can perform MIMO and can receive multiple layers during MIMO operation. The baseband processor performs conversion functions between baseband signals and bit strings according to the system's physical layer specifications. For example, during data transmission, the baseband processor encodes and modulates the transmitted bit string to generate complex symbols. Additionally, during data reception, the baseband processor demodulates and decodes the baseband signal provided by the RF processor to recover the received bit string.

[0213] The main processor 4a-04 controls all operations except for movement. The main processor 4a-04 processes user input received from I / O unit 4a-05, stores the data in storage unit 4a-02, controls controller 4a-01 to perform the required mobile communication operations, and forwards user data to I / O unit 4a-05.

[0214] I / O unit 4a-05 consists of devices for inputting and outputting user data, such as a microphone and a screen. I / O unit 4a-05 performs user data input and output according to instructions from the main processor.

[0215] Figure 4b This is a block diagram illustrating the configuration of a base station according to the present disclosure.

[0216] As shown in the figure, the base station includes a controller 4b-01, a storage unit 4b-02, a transceiver 4b-03, and a backhaul interface unit 4b-04.

[0217] Controller 4b-01 controls the overall operation of the main base station. For example, controller 4b-01 receives / transmits signals via transceiver 4b-03 or backhaul interface unit 4b-04. Additionally, controller 4b-01 records and retrieves data in storage unit 4b-02. For this purpose, controller 4b-01 may include at least one processor. The controller controls the transceiver, storage unit, and backhaul interface, enabling execution... Figure 2a The base station operation shown.

[0218] Storage unit 4b-02 stores data used for the operation of the main base station, such as basic procedures, application programs, and configuration information. Specifically, storage unit 4b-02 can store information about bearers assigned to accessing UEs, measurement results reported from accessing UEs, etc. Additionally, storage unit 4b-02 can store information used to determine whether to provide multiple connections to a UE or interrupt multiple connections. Furthermore, storage unit 4b-02 provides the stored data according to requests from controller 4b-01.

[0219] The transceiver 4b-03 consists of an RF processor, a baseband processor, and multiple antennas. The RF processor performs functions such as transmitting / receiving signals over the wireless channel, including signal band conversion and amplification. Specifically, the RF processor up-converts the baseband signal provided by the baseband processor into an RF band signal, transmits this signal through the antennas, and down-converts the RF band signal received through the antennas back into a baseband signal. The RF processor may include transmit filters, receive filters, amplifiers, mixers, oscillators, DACs, ADCs, etc. The RF processor can perform downlink MIMO operation by transmitting at least one layer. The baseband processor performs conversion functions between baseband signals and bit strings according to the physical layer specifications of the first radio access technology. For example, during data transmission, the baseband processor encodes and modulates the transmitted bit string to generate complex symbols. Additionally, during data reception, the baseband processor demodulates and decodes the baseband signal provided by the RF processor to recover the received bit string.

[0220] The backhaul interface unit 4b-04 provides an interface for communicating with other nodes within the network. The backhaul interface unit 4b-04 converts bit strings sent from the base station to another node (e.g., another base station or the core network) into physical signals, and converts physical signals received from another node into bit strings.< / rrcresume> < / resumerequest> < / sibx> < / suspendconfig>

Claims

1. A method for a terminal in a wireless communication system, the method comprising the following steps: Receive a first downlink control message from the first NR cell, which includes a first timer value and indicates a transition to the RRC_INACTIVE state; Suspend all radio bearers except signaling radio bearer 0 and start the first timer; Perform cell selection; Receive system information from the second NR cell, including information related to the second recovery process, the second timer value, and the third timer value; Initiate the recovery process; At least restore signaling radio bearer 1; Send a first uplink control message including the terminal's identifier and the reason for recovery; as well as Receive the second downlink control message, which includes cell group configuration information. Specifically, if a first recovery procedure is initiated to transition the terminal from the RRC_INACTIVE state to the RRC_CONNECTED state, then after applying the default signaling radio bearer 1 configuration and before restoring signaling radio bearer 1, a second timer is started, and upon receiving the second downlink control message, the first and second timers are stopped before applying cell group configuration information. Specifically, if a second recovery process is initiated when the terminal is in the RRC_INACTIVE state to send and receive data, then after the signaling radio bearer 1 is configured in the inactive context of the application terminal, the first timer is stopped and the third timer is started before the signaling radio bearer 1 is restored, and the third timer is stopped before the application cell group configuration information is received when the second downlink control message is received.

2. The method according to claim 1, wherein, When the second timer expires, the terminal context is discarded, cell selection is performed, and the system transitions to the RRC_IDLE state. When the third timer expires, the terminal context is stored, all radio bearers except signaling radio bearer 0 are suspended, and the first timer is started.

3. The method according to claim 1, wherein, After initiating the second recovery process, if the first timer expires, it is first determined whether the second recovery process is in progress. If the second recovery process is not in progress, the RAN notification region (RNA) update process is initiated.

4. The method according to claim 1, wherein, When the first timer expires, an RNA update process is initiated in the current cell, and when the third timer expires, a suitable cell is selected and the RNA update process is started.

5. A terminal in a wireless communication system, comprising: A transceiver, configured to send and receive signals; as well as Controller The controller is configured as follows: Receive a first downlink control message from the first NR cell, which includes a first timer value and indicates a transition to the RRC_INACTIVE state; Suspend all radio bearers except signaling radio bearer 0 and start the first timer; Perform cell selection; Receive system information from the second NR cell, including information related to the second recovery process, the second timer value, and the third timer value; Initiate the recovery process; At least restore signaling radio bearer 1; Send a first uplink control message including the terminal's identifier and the reason for recovery; and Receive the second downlink control message, which includes cell group configuration information. Specifically, if a first recovery procedure is initiated to transition the terminal from the RRC_INACTIVE state to the RRC_CONNECTED state, then after applying the default signaling radio bearer 1 configuration and before restoring signaling radio bearer 1, a second timer is started, and upon receiving the second downlink control message, the first and second timers are stopped before applying cell group configuration information. Specifically, if a second recovery process is initiated when the terminal is in the RRC_INACTIVE state to send and receive data, then after the signaling radio bearer 1 is configured in the inactive context of the application terminal, the first timer is stopped and the third timer is started before the signaling radio bearer 1 is restored, and the third timer is stopped before the application cell group configuration information is received when the second downlink control message is received.

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