Method and apparatus for processing downlink RRC segmented messages in next-generation mobile communication systems

Abstract

This disclosure relates to a communication technology and system that integrates IoT technology with fifth-generation (5G) or pre-5G communication systems, wherein the fifth-generation (5G) or pre-5G communication systems support higher data transmission rates than fourth-generation (4G) communication systems such as LTE. This disclosure can be applied to smart services based on 5G communication technology and IoT-related technologies (e.g., smart homes, smart buildings, smart cities, smart cars or connected cars, healthcare, digital education, retail, security and safety-related services, etc.). According to various embodiments of this disclosure, a method and apparatus for processing downlink RRC segmented messages in a next-generation mobile communication system can be provided.

Description

Technical Field

[0001] This disclosure relates to a mobile communication system, and more particularly to a method for a base station to segment and transmit downlink RRC reconfiguration messages, and the operation of a UE that receives a downlink RRC reconfiguration message. Background Technology

[0002] To meet the growing demand for wireless data services 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 referred to as "beyond 4G networks" or "post-LTE systems".

[0003] To achieve higher data rates, 5G communication systems are being considered for implementation in ultra-high frequency (mmWave) bands (e.g., the 60 GHz band). To mitigate path loss of radio waves and increase transmission distance in the mmWave band, beamforming, massive MIMO, full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and massive MIMO technologies are being discussed for 5G communication systems.

[0004] In addition, in 5G communication systems, system network improvements are being developed based on evolved small cells, advanced small cells, cloud radio access networks (cloud RAN), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, mobile networks, cooperative communication, cooperative multipoint (CoMP), and receiver interference cancellation.

[0005] In addition, hybrid FSK and QAM modulation (FQAM) and sliding window superposition coding (SWSC) have been developed as advanced coding and modulation (ACM) systems, as well as filter bank multicarrier (FBMC), non-orthogonal multiple access (NOMA) and sparse code multiple access (SCMA) as advanced access technologies.

[0006] For existing 4G systems, 5G systems are considering supporting various services. For example, the most representative services may include enhanced mobile broadband (eMBB), ultra-reliable and low-latency communication (URLLC), massive machine-type communication (mMTC), and evolved multimedia broadcast / multicast service (eMBMS). Furthermore, a system used to provide URLLC services can be called an URLLC system, and a system used to provide eMBB services can be called an eMBB system. Additionally, the terms "service" and "system" are used interchangeably.

[0007] Unlike existing 4G systems, URLLC service is a newly considered service in 5G systems and requires ultra-high reliability (e.g., approximately 10) compared to other services. -5 The requirements include low packet error rate and low latency (e.g., approximately 0.5 milliseconds). To meet these stringent requirements, URLLC services may need to apply a shorter Transmission Time Interval (TTI) than eMBB services, and various operational methods utilizing this TTI have been considered.

[0008] On the other hand, the Internet is evolving from a human-centric connectivity network to an Internet of Things (IoT) network, in which humans generate and consume information, while the IoT network exchanges and processes information between distributed components such as things. IoE technology is a combination of IoT technology and big data processing technology through connectivity with cloud servers. IoT implementation requires technological elements such as sensing technology, wired / wireless communication and network infrastructure, service interface technology, and security technology; therefore, technologies such as sensor networks, machine-to-machine (M2M) communication, and machine-type communication (MTC) for connecting things are currently under investigation.

[0009] This IoT environment can provide intelligent Internet of Things (IT) services that create new value for human life by collecting and analyzing data generated between connected things. Through the convergence and combination of existing information technology (IT) and various industrial applications, IoT can be applied to a wide range of fields, including smart homes, smart buildings, smart cities, smart cars or connected cars, smart grids, healthcare, smart devices, and advanced medical services.

[0010] Consistent with this, various attempts have been made to apply 5G communication systems to IoT networks. For example, technologies such as sensors, network machine-to-machine (M2M) communication, and machine-type communication (MTC) can be implemented using beamforming, MIMO, and array antenna technologies corresponding to 5G communication technologies. The application of cloud radio access networks (cloud RAN), as a big data processing technology, can also be seen as an example of the convergence between 5G and IoT technologies. Summary of the Invention

[0011] [Technical Issues]

[0012] In NR systems, during the series of processes in which a UE receives a request for its capabilities from a base station and sends a report to the base station, a method can be introduced for segmenting and transmitting UE capability information messages when the UE capability information exceeds the maximum size of a PDCP Service Data Unit (SDU). Similarly, even in the case of downlink Radio Resource Control (RRC) messages, situations may arise where configuration information exceeds the maximum PDCP SDU size. Furthermore, where segmentation of downlink RRC messages is permitted, UE operations supporting this may be necessary. Specifically, when an operation for generating an RRC reconstruction is triggered in the UE, operations by the UE to process segmented RRC messages stored in the UE's RRC layer may be required.

[0013] The technical problems to be solved in this disclosure are not limited to those mentioned above, and those skilled in the art to which this disclosure pertains will be able to clearly understand other unmentioned technical problems from the following description.

[0014] [Solution to the problem]

[0015] To address the aforementioned problems, according to this disclosure, a method performed by a UE in a wireless communication system includes: receiving a request message from a base station reporting capability information for the UE; in response to the request message, sending a response message to the base station including an indicator for indicating whether the UE supports segments of a downlink radio resource control (RRC) message; receiving segmented messages of the downlink RRC message from the base station; and, if an event related to RRC reconstruction occurs before the last segmented message of the downlink RRC message is received, determining whether to discard or retain the received segmented message according to predetermined criteria.

[0016] Furthermore, according to another embodiment of this disclosure, a method performed by a base station in a wireless communication system includes: sending a request message for a report of capability information of the UE to a UE; receiving a response message from the UE in response to the request message, the response message including an indicator for indicating whether the UE supports segmentation of a downlink radio resource control (RRC) message; generating a downlink RRC message; generating segmented messages of the downlink RRC message based on the indicator if the size of the downlink RRC message is greater than a predetermined size; and sending the segmented messages of the downlink RRC message to the UE, wherein if an event related to RRC reconstruction occurs before the last segment of the downlink RRC message is sent, the segmented messages are discarded or retained according to a predetermined criterion.

[0017] Furthermore, according to another embodiment of this disclosure, the UE in the wireless communication system includes: a transceiver; and a controller configured to: control the receiving, via the transceiver, of a request message reporting capability information of the UE from a base station; control the sending, via the transceiver, of a response message to the base station in response to the request message, the response message including an indicator indicating whether the UE supports segmentation of downlink radio resource control (RRC) messages; control the receiving, via the transceiver, of segmented messages of downlink RRC messages from the base station; and, in the event of an event related to RRC reconstruction occurring before the last segmented message of the downlink RRC message is received, determine, according to predetermined criteria, whether to discard or retain the received segmented messages.

[0018] Furthermore, according to another embodiment of this disclosure, a base station in a wireless communication system includes: a transceiver; and a controller configured to: control the transmission of a request message for a report of capability information of the UE to the UE via the transceiver; control the reception of a response message from the UE via the transceiver in response to the request message, the response message including an indicator for indicating whether the UE supports segmentation of a downlink radio resource control (RRC) message; control the generation of a downlink RRC message; control the generation of segmented downlink RRC message segments based on the indicator if the size of the downlink RRC message is greater than a predetermined size; control the transmission of the segmented downlink RRC message segments to the UE via the transceiver; and control the discarding or retention of the segmented message segments according to a predetermined criterion if an event related to RRC reconstruction occurs before the last segmented downlink RRC message segment is transmitted.

[0019] [Beneficial effects of the invention]

[0020] According to embodiments of this disclosure, since downlink segmented RRC messages are introduced into the NR system, it is even possible to generate and transmit downlink RRC messages exceeding the maximum PDCP SDU size. Furthermore, when an RRC reconstruction operation is triggered in the UE, it becomes clear how to handle segmented RRC messages stored in the UE's RRC layer, and therefore unnecessary messages do not need to be stored in the UE's buffer, thus enabling efficient UE buffer management.

[0021] The effects that can be obtained in this disclosure are not limited to those described above, and other unmentioned effects will be clearly understood by those skilled in the art to which this disclosure pertains from the following description. Attached Figure Description

[0022] Figure 1 This is a diagram illustrating the structure of an LTE system according to an embodiment of the present disclosure.

[0023] Figure 2This is a diagram illustrating the radio protocol structure in an LTE system according to an embodiment of the present disclosure.

[0024] Figure 3 This is a diagram illustrating the structure of a next-generation mobile communication system according to an embodiment of the present disclosure.

[0025] Figure 4 This is a diagram illustrating the radio protocol structure of a next-generation mobile communication system according to an embodiment of the present disclosure.

[0026] Figure 5 This diagram illustrates the operation between the UE, the primary node (MN) base station, and the secondary node (SN) base station in order to apply segmentation to RRC control messages transmitted over the downlink in an NR system according to an embodiment of this disclosure.

[0027] Figure 6 This is a diagram illustrating a method for applying segmentation to downlink RRC messages in an NR system according to an embodiment of the present disclosure.

[0028] Figure 7 This diagram illustrates the entire operation when segmentation is applied to downlink RRC messages according to an embodiment of this disclosure, and specifically illustrates the operation between the UE, the primary node (MN) base station, and the secondary node (SN) base station depending on the specific situation.

[0029] Figure 8 This is a diagram illustrating the operation of a UE for processing downlink segment RRC messages for each event when an event related to RRC reconstruction occurs, as a first embodiment of this disclosure.

[0030] Figure 9 This is a diagram illustrating the operation of a UE for processing downlink segmented RRC messages for each event when an event related to RRC reconstruction occurs in a state configured with primary cell group (MCG) fast recovery, as a second embodiment of this disclosure.

[0031] Figure 10 This is a diagram illustrating the operation of a base station according to an embodiment of the present disclosure.

[0032] Figure 11 This is a diagram illustrating the block configuration of a UE according to an embodiment of the present disclosure.

[0033] Figure 12 This is a diagram illustrating the block configuration of a base station according to an embodiment of the present disclosure. Detailed Implementation

[0034] The operating principles of this disclosure will be described in detail below with reference to the accompanying drawings. In describing this disclosure, detailed descriptions of relevant known functions or configurations will be omitted if it would unnecessarily obscure the essential points of the disclosure. Furthermore, the terminology described below has been defined in consideration of the functions in this disclosure and may vary depending on the intent or practice of the user or operator. Therefore, each term should be defined based on the content throughout the specification. In the following description, for ease of description, terms for identifying access nodes, terms for representing network entities, terms for representing messages, terms for representing interfaces between network entities, and terms for representing various types of identity information have been shown. Therefore, this disclosure is not limited to the following terms, and other terms used to represent objects with equivalent technical meaning may be used.

[0035] For ease of explanation, the terms and names defined in the 3GPP LTE standard are used in this disclosure. However, this disclosure is not limited to the terms and names, and can be applied equivalently to systems conforming to other standards.

[0036] Figure 1 This is a diagram illustrating the structure of an LTE system according to an embodiment of the present disclosure.

[0037] Reference Figure 1 The radio access network of an LTE system can consist of evolved Node Bs (hereinafter referred to as "eNB", "Node B" or "base station") 105, 110, 115 and 120, a Mobility Management Entity (MME) 125 and a Service Gateway (S-GW) 130. User equipment (hereinafter referred to as "UE" or "terminal") 135 can access external networks through eNBs 105 to 120 and S-GW 130.

[0038] exist Figure 1In this context, eNBs 105 to 120 correspond to existing Node Bs in the UMTS system. eNBs 105 to 120 can connect to UE 135 on the radio channel and play a more complex role compared to existing Node Bs. In LTE systems, since all user services, including real-time services such as Voice over IP (VoIP) via Internet Protocol, are served on a shared channel, an entity is necessary to perform scheduling by collecting state information such as the buffer state, available transmission power state, and channel state of UE 135, and eNBs 105 to 120 can handle this. Typically, one eNB 105 to 120 can control multiple cells. For example, to achieve a transmission speed of 100 Mbps, the LTE system can use, for example, Orthogonal Frequency Division Multiplexing (hereinafter referred to as "OFDM") as the radio access technology within a 20 MHz bandwidth. Furthermore, the LTE system can employ an Adaptive Modulation and Coding (hereinafter referred to as "AMC") scheme, which determines the modulation scheme and channel coding rate to match the channel state of UE 135. The S-GW 130 is the entity that provides data bearers and can generate or remove data bearers under the control of the MME 125. The MME 125 is the entity responsible not only for the mobility management functions of the UE 135 but also for various control functions, and can be connected to multiple base stations 105 to 120.

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

[0040] refer to Figure 2 In the UE or eNB, the radio protocol of the LTE system consists of PDCP 205 or 240, Radio Link Control (RLC) 210 or 235, and Media Access Control (MAC) 215 or 230. The Packet Data Convergence Protocol (PDCP) 205 or 240 is responsible for IP header compression / decompression operations. The main functions of PDCP 205 or 240 can be summarized as follows.

[0041] -Header compression and decompression: ROHC only

[0042] -Transmit user data

[0043] - Deliver upper-layer PDUs sequentially during PDCP reconstruction for RLC AM

[0044] - For split bearers in the DC (RLC AM only): PDCP PDU routing for transmission and PDCP PDU reordering for reception.

[0045] - Repeated detection of lower-level SDUs during PDCP reconstruction for RLC AM

[0046] - For RLC AM, retransmit PDCP SDU during handover; and for separate bearers in DC, retransmit PDCP PDU during PDCP data recovery.

[0047] - Encryption and decryption

[0048] -Timer-based SDU dropping in the uplink

[0049] The Radio Link Control (RLC) 210 or 235 can perform ARQ operations by reconfiguring PDCP Protocol Data Units (PDCP PDUs) of appropriate size. The main functions of the RLC 210 or 235 can be summarized as follows.

[0050] -Transmit upper-layer PDU

[0051] - Error correction via ARQ (AM data transmission only)

[0052] - Cascading, segmentation, and reassembly of RLC SDUs (UM and AM data transfer only)

[0053] - Re-segmentation of RLC data PDUs (AM data transmission only)

[0054] - Reordering of RLC data PDUs (for UM and AM data transfers only)

[0055] - Duplicate detection (only for UM and AM data transmissions)

[0056] - Protocol error detection (AM data transmission only)

[0057] -RLC SDU Discard (for UM and AM data transfers only)

[0058] -RLC Reconstruction

[0059] MAC 215 or 230 connects to several RLC layer devices configured in a UE and can perform functions such as multiplexing RLC PDUs to MAC PDUs and demultiplexing RLC PDUs from MAC PDUs. The main functions of MAC 215 or 230 can be summarized as follows.

[0060] Mapping between logical channels and transport channels

[0061] - Multiplexing MAC SDUs belonging to one or different logical channels into a transport block (TB) delivered to the physical layer on the transport channel / Demultiplexing MAC SDUs belonging to one or different logical channels from a transport block (TB) delivered from the physical layer on the transport channel.

[0062] - Scheduling Information Report

[0063] - Error correction via HARQ

[0064] Priority processing between logical channels of a UE

[0065] Priority handling among UEs via dynamic scheduling

[0066] -MBMS service identifier

[0067] -Transmission format selection

[0068] -filling

[0069] Physical layer 220 or 225 can perform channel coding and modulation of upper-layer data and generate OFDM symbols for transmission over a radio channel, or it can perform demodulation and channel decoding of OFDM symbols received over a radio channel and transmit the OFDM symbols to the upper layer. Furthermore, for additional error correction even in physical layer 220 or 225, Hybrid ARQ (HARQ) can be used, and the receiver can use one bit to indicate whether it wants to receive packets transmitted from the transmitter. This can be referred to as "HARQ ACK / NACK information". Downlink HARQ ACK / NACK information for uplink transmission can be transmitted on the Physical Hybrid ARQ Indicator Channel (PHICH) physical channel, and uplink HARQ ACK / NACK information for downlink transmission can be transmitted on the Physical Uplink Control Channel (PUCCH) or Physical Uplink Shared Channel (PUSCH) physical channel.

[0070] Meanwhile, PHY layer 220 or 225 can consist of one or more frequencies / carriers, and the technique for configuring and using multiple frequencies simultaneously can be carrier aggregation (hereinafter referred to as "CA"). In addition to using only one carrier for communication between the user equipment (UE) and the base station (E-UTRAN NodeB or eNB), CA technology can significantly increase the transmission capacity with the number of subcarriers by additionally using a primary carrier and one or more secondary carriers. Furthermore, in LTE, the cell in a base station using the primary carrier can be referred to as the "primary cell (PCell)," and the secondary carrier can be referred to as the "secondary cell (SCell)."

[0071] Although not shown in the accompanying drawings, a radio resource control (RRC) layer may exist above the PDCP layer of the UE and the base station, and the RRC layer may send and receive configuration control messages related to access and measurement for radio resource control.

[0072] Figure 3This is a diagram illustrating the structure of a next-generation mobile communication system according to an embodiment of the present disclosure.

[0073] refer to Figure 3 The radio access network of a next-generation mobile communication system can consist of a new radio node B (hereinafter referred to as NR NB or gNB) 310 and a new radio core network (NR CN) or a next-generation core network (NG CN) 305. New radio user equipment (hereinafter referred to as NR UE or UE, or terminal) 315 can access external networks through NR NB 310 and NR CN 305.

[0074] exist Figure 3 In this context, the NR NB 310 can correspond to an evolved Node B (eNB) in an existing LTE system. The NR NB 310 connects to the NR UE 315 on the radio channel and thus can provide superior service compared to existing Node Bs. In next-generation mobile communication systems, all user traffic is served on a shared channel, thus requiring a means to perform scheduling by incorporating state information such as the buffer state, available transmission power state, and channel state of the UE 315; the NR NB 310 can handle this. Typically, one NR NB 310 can control multiple cells. To achieve ultra-high-speed data transmission compared to existing LTE, bandwidth equal to or greater than the existing maximum bandwidth can be applied, and Orthogonal Frequency Division Multiplexing (OFDM) can be considered as the radio access technology, supplemented by beamforming. Furthermore, an Adaptive Modulation and Coding (AMC) scheme can be applied, which determines the modulation scheme and channel coding rate to match the channel state of the UE 315. The NR CN 305 can perform mobility support, bearer establishment, and QoS configuration functions. The NR CN 305 is a device responsible not only for the mobility management functions of the UE 315 but also for various control functions, and can connect to multiple base stations 310. Furthermore, the next-generation mobile communication system can interoperate with existing LTE systems, and the NR CN 305 can connect to the MME 325 via a network interface. The MME 325 can connect to the eNB 330, which serves as an existing base station.

[0075] Figure 4 This is a diagram illustrating the radio protocol structure of a next-generation mobile communication system according to an embodiment of the present disclosure.

[0076] refer to Figure 4 In a UE or NR base station, the radio protocols of a next-generation mobile communication system may include NR SDAP401 or 445, NR PDCP 405 or 440, NR RLC 410 or 435, and NR MAC 415 or 430.

[0077] The main functions of NR SDAP 401 or 445 may include some of the following functions.

[0078] -Transmission of user plane data

[0079] Mapping between QoS flows and DRB for both DL and UL

[0080] - Mark the QoS flow ID in both DL and UL groups, and mark the mapping of reflected QoS flows to DRB for UL SDAP PDUs.

[0081] For SDAP layer devices, the UE can be configured via RRC messages to use the SDAP layer device header or functionality for each PDCP layer device, bearer, or logical channel. If the SDAP header is configured, the 1-bit NAS QoS reflection configuration indicator (NAS reflected QoS) and 1-bit AS QoS reflection configuration indicator (AS reflected QoS) in the SDAP header can indicate whether the UE can update or reconfigure the mapping information regarding uplink and downlink QoS flows and data bearers. The SDAP header may include QoS flow ID information indicating QoS. QoS information can be used for data processing priorities such as supporting smooth service and scheduling information.

[0082] The main functions of NR PDCP 405 or 440 may include some of the following functions.

[0083] -Header compression and decompression: ROHC only

[0084] -Transmit user data

[0085] - Ordered delivery of high-level PDUs

[0086] -Disordered delivery of high-level PDUs

[0087] - Reordering of received PDCP PDUs

[0088] -Duplicate detection of lower-level SDUs

[0089] -PDCP SDU retransmission

[0090] - Encryption and decryption

[0091] - Timer-based SDU dropping in the uplink

[0092] As described above, the reordering of the NR PDCP device can mean reordering the PDCP PDUs received from the lower layer based on the PDCP sequence number (SN), and can include transmitting data to the upper layer in the reordered order or transmitting it immediately regardless of the order, and can include recording lost PDCP PDUs by rearranging the order, status reports for lost PDCP PDUs to the transmitting side, and retransmission requests for lost PDCP PDUs.

[0093] The main functions of the NR RLC 410 or 435 may include some of the following functions.

[0094] -Transmission of upper-layer PDUs

[0095] - Ordered delivery of high-level PDUs

[0096] -Disordered delivery of high-level PDUs

[0097] -Error correction via ARQ

[0098] Cascading, segmentation, and reassembly of RLC SDUs

[0099] - Resegmentation of RLC data PDUs

[0100] - RLC data PDU reordering

[0101] -Duplicate detection

[0102] -Protocol error detection

[0103] -RLC SDU discard

[0104] -RLC Reconstruction

[0105] As described above, sequential delivery by an NR RLC device can mean sequential delivery of RLC SDUs received from the lower layer to the upper layer. When an original RLC SDU is segmented into several RLC SDUs and received, sequential delivery by an NR RLC device can include RLC SDU reassembly and delivery, reordering of received RLC PDUs based on the RLC sequence number (SN) or PDCP sequence number (SN), recording lost RLC PDUs through reordering, status reporting to the transmitting side for lost RLC PDUs, and retransmission requests for lost RLC PDUs. Sequential delivery by an NR RLC device can include: if a lost RLC SDU exists, only RLC SDUs preceding the lost RLC SDU are delivered sequentially to the upper layer; if, despite the existence of a lost RLC SDU, a timer has expired, all RLC SDUs received before the start of a specific timer are delivered sequentially to the upper layer; or if, despite the existence of a lost RLC SDU, a specific timer has expired, all RLC SDUs received up to the present are delivered sequentially to the upper layer. The NR RLC device can process RLC PDUs in the order they are received (according to arrival order, regardless of sequence number or sequence number order) and can transmit the processed RLC PDUs to the PDCP device in an out-of-order manner. In the case of receiving segments, the NR RLC device can receive segments stored in a buffer or segments to be received later, reconfigure them into a complete RLC PDU, and then transmit the reconfigured RLC PDU to the PDCP device. The NR RLC layer may not include concatenation functionality, and this functionality can be performed by the NR MAC layer or replaced by the multiplexing functionality of the NR MAC layer.

[0106] As described above, out-of-order delivery of NR RLC devices can mean the function of directly transmitting RLC SDUs received from lower layers to upper layers, regardless of their order, and if an original RLC SDU is segmented into multiple RLC SDUs and received, out-of-order delivery of NR RLC devices can include the reassembly and delivery of RLC SDUs, as well as the function of storing and sorting the RLC SN or PDCP SN of received RLC PDUs and recording lost RLC PDUs.

[0107] The NR MAC 415 or 430 can be connected to several NR RLC layer devices configured in a UE, and the main functions of the NR MAC may include some of the following functions.

[0108] Mapping between logical channels and transport channels

[0109] - MAC SDU multiplexing / demultiplexing

[0110] - Scheduling Information Report

[0111] - HARQ functionality (error correction via HARQ)

[0112] Priority processing between logical channels of a UE

[0113] Priority handling among UEs via dynamic scheduling

[0114] -MBMS service identifier

[0115] -Transmission format selection

[0116] -filling

[0117] The NR PHY layer 420 or 425 can perform channel coding and modulation of upper-layer data to configure and transmit OFDM symbols on a radio channel, or it can perform demodulation and channel decoding of OFDM symbols received on a radio channel to transmit the demodulated and channel-decoded symbols to the upper layer.

[0118] Figure 5 This diagram illustrates the operation between the UE, the primary node (MN) base station, and the secondary node (SN) base station in order to apply segmentation to RRC control messages transmitted over the downlink in an NR system according to an embodiment of this disclosure.

[0119] The RRCReconfiguration and RRCResume messages can be used as examples of RRC control messages, and an RRC control message can be a specific downlink RRC control message that needs to be segmented due to its large size. In the embodiments of this disclosure, RRCReconfiguration will be generalized and explained.

[0120] Basically, in state (505) connected to serving base station (eNB or gNB) 502, UE 501 is required to receive configuration information for data transmission / reception with the base station. In operation 510, base station 502 or 503 can determine that it should transmit an RRCReconfiguration message to UE 501 and can generate corresponding information. In such cases... Figure 5 In the state of dual connectivity (hereinafter referred to as "DC") as shown, depending on how RRCReconfiguration is transmitted, the following situations can occur: situation 1, situation 2 and situation 3.

[0121] Scenario 1: When the master node (MN) generates an RRC message that includes the primary cell group (MCG) configuration information, the base station can transmit the generated RRC message through SRB1.

[0122] Scenario 2: If the MN has transmitted the secondary node (SN) configuration information and generated an RRC message including MCG / SCG configuration information, the base station can transmit the generated RRC message through SRB1.

[0123] Scenario 3: When the SN generates an RRC message that includes subcell group (SCG) configuration information, the base station can transmit the generated RRC message through SRB3.

[0124] At operation 515, if the RRC control message generated at operation 510 exceeds 9000 bytes, the maximum size corresponding to the PDCP SDU, the base station may segment the corresponding RRC control message (e.g., an RRCReconfiguration message). That is, the entire RRCReconfiguration message can be segmented into segments of 9000 bytes each, and the final segment can be a segment with the remaining size obtained by subtracting the sum of the segmented RRC message sizes from the total size of the RRC control message generated at operation 510 (the entire message size). At operation 520, the base station may transmit the generated segmented RRC messages (segmented RRCReconfiguration messages) to the UE one by one. In this case, the transmitted segmented RRC messages should be transmitted sequentially according to their sequence numbers and should not be interrupted by other RRC messages. That is, when a segmented RRC message is transmitted, other RRC messages are not transmitted. At operation 525, after receiving all segmented RRC messages, the UE can recover the entire RRC message information by decoding and reassembling the received segmented RRC messages.

[0125] Figure 6 This is a diagram illustrating a method for applying segmentation to downlink RRC messages in an NR system according to an embodiment of the present disclosure.

[0126] Referring to the accompanying diagram, the detailed segmentation message will be described using the RRCReconfiguration message as an example.

[0127] When applying segmentation based on DL DCCH messages, a new downlink segmented RRC message can be introduced. As an example, a new DL DCCH message called DLDedicatedMessageSegment can be introduced and used to transmit downlink segmented RRC. If the complete DL DCCH message 605 (e.g., a DL DCCH message including an RRCReconfiguration message) exceeds 9000 bytes, the base station can apply segmentation, such that the corresponding message is segmented into 8997 bytes as shown in 630 or 655, and a 3-byte (24-bit) downlink segmented RRC message header is added to it. Here, the size of the RRC message header and the segmented RRC message is not predetermined but can vary depending on the size of the introduced fields. The final segmented message 680 can have a size obtained by subtracting the sum of the sizes of the 9000-byte segments from the total size.

[0128] The header of a downlink segmented RRC message requires 6 bits for DL ​​DCCH type configuration (610, 635, and 660: bits for CHOICE structure and DLDedicatedMessageSegment message indication), and 2 bits for the segment index 615, 640, and 665 for the corresponding segmented UE capability information message. The segment index is an identifier representing the segment number of the corresponding segmented RRC message, and if the segment index is 2 bits, it corresponds to the case where the maximum segment size is configured to be 4, and the number of bits in the segment index can vary according to the maximum configuration value. Since the corresponding segments can be transmitted sequentially via the PDCP SN, the corresponding identifier can always be included, or it may not be present. However, a 1-bit indicator 620, 645, or 670 indicating whether a particular segment is the last segment should be included in the corresponding header. If the corresponding LastSegment indicator is indicated as 0 to indicate that the particular segment is not the last segment, it means that the corresponding packet is not the last segment, and the base station receiving the corresponding message can know that the corresponding packet has the maximum size. In addition, padding bits can be added for byte alignment during packetization. The padding bits can vary depending on the previous header bits and the segment size. Furthermore, the length field (625, 650, or 675, depending on the length determination) indicating the length of the segmented RRC message requires 15 bits. This could mean the number of bits used to represent 8997 bytes. In the method for padding size, if the PDCP SDU size is set to 9000, a PDCPSN can be added, and a PDCP PDU can be generated.

[0129] The following embodiments of this disclosure present the UE and base station operations under conditions that may occur during the segmentation operation when downlink segmentation is applied to downlink RRC control messages, particularly RRC reconfiguration messages and RRC recovery messages. These conditions relate to RRC reconstruction operations, and it will be described how the UE processes the corresponding RRC segment based on various conditions that trigger the corresponding RRC segmentation.

[0130] Figure 7 This is a diagram illustrating the entire operation when segments are applied to downlink RRC messages according to embodiments of this disclosure, and specifically illustrates the operation between the UE, the primary node (MN) base station, and the secondary node (SN) base station depending on the specific situation.

[0131] The RRCReconfiguration and RRCResume messages can be used as examples of RRC control messages and can be applied to specific downlink RRC control messages that require segmentation due to their large size. RRCReconfiguration will be summarized and explained below in this disclosure.

[0132] Basically, UE 701 is required to receive configuration information for data transmission / reception with the base station while connected to the serving base station (eNB or gNB) 702 (705). In the above operation, it can be assumed that dual connectivity (DC) is configured and the MN and SN are in a connected state. In step 710, the base station 702 or 703 can determine that it should transmit an RRCReconfiguration message to UE 701 and can generate corresponding information. In this case, the MNRRCReconfiguration message can exist within the RRCReconfiguration message generated by the MN, and the SNRRCReconfiguration message can be encapsulated. Figure 7 As shown, in the state of configured dual connectivity (hereinafter referred to as "DC"), the following may occur depending on how the RRCReconfiguration message is transmitted.

[0133] Scenario 1: When the master node (MN) generates an RRC message that includes MCG configuration information, the base station can transmit the generated RRC message through SRB1.

[0134] Scenario 2: If the MN has transmitted the secondary node (SN) configuration information and generated an RRC message including MCG / SCG configuration information, the base station can transmit the generated RRC message through SRB1.

[0135] Scenario 3: When the SN generates an RRC message that includes SCG configuration information, the base station can transmit the generated RRC message through SRB3.

[0136] At step 715, if the RRC control message generated at step 710 exceeds 9000 bytes, which corresponds to the maximum size of the PDCP SDU, the base station may apply segmentation to the corresponding RRC control message (e.g., RRCReconfiguration). That is, the entire RRCReconfiguration can be segmented into segments of 9000 bytes each, and the final segment can be a segment with the remaining size obtained by subtracting the sum of the segmented RRC message sizes from the total message size. Based on the above, the base station operation will be described in detail below.

[0137] - Perform segmentation operations on the RRCReconfiguration messages generated by MN (case 1 and case 2).

[0138] ■ Check whether the generated RRC message is for MN or SN.

[0139] ◆In the case of MN's RRC message,

[0140] ● Store / generate segmented RRCReconfiguration messages in DLDedicatedMessageSegment

[0141] ● Send multiple DLDedicatedMessageSegment messages containing all complete RRCReconfigurations to SRB1

[0142] ● Transmit messages sequentially via SRB1 without interrupting another DL RRC message.

[0143] - Perform segmentation operations on the RRCReconfiguration message generated by SN (Case 3)

[0144] ■ Check whether the generated RRC message is for MN or SN.

[0145] ◆When the RRC message is for the SN and SRB3 is configured,

[0146] ● Store / generate segmented RRCReconfiguration messages in DLDedicatedMessageSegment

[0147] ● Send multiple DLDedicatedMessageSegment messages containing all complete RRCReconfigurations to SRB3

[0148] ● Transmit messages sequentially via SRB3 without interrupting another DL RRC message.

[0149] As described above, in step 715, the base station can transmit the generated segmented RRC messages (segmented RRCReconfiguration messages) to the UE one by one via the configured SRB. In this case, the transmitted segmented RRC messages should be transmitted sequentially according to the sequence number (or segment index) and should not be interrupted by other RRC messages. That is, when a segmented RRC is transmitted, other RRC messages are not transmitted. However, as can be identified in step 525, this disclosure manages situations where other conditions occur before all segmented RRCs (DLDedicatedMessageSegments) are transmitted. As an example, if there are a total of N segmented RRC messages, this can correspond to the state where the (N-1)th segment has been transmitted to the UE via the configured SRB but the final Nth segmented RRC message has not yet been transmitted. Furthermore, the corresponding situation is not limited to the above example, and in the case where there are a total of N segmented RRC messages, this can even correspond to the situation where this condition occurs before all N segmented RRC messages are transmitted to the UE.

[0150] For reference, already referenced Figure 5 The scenario described is where the entire segmented RRC message is securely transmitted. In the following embodiments, this scenario will be described in more detail, and a simplified operation will be described with reference to the accompanying drawings. In short, in the current UE's RRC layer, since it is assumed that RRC messages are not stored, but rather processed immediately upon arrival at a lower layer, and processed immediately upon receipt, RRC messages stored in the RRC layer are not considered. However, when RRC segmentation is introduced, segments can be stored in the UE's RRC layer, and since the stored segments correspond to a certain amount of information that will occupy data, it may be necessary to explicitly discard data at the RRC layer in certain situations.

[0151] In a specific embodiment, if the UE is unable to receive all segmented RRC messages, there may be a situation where an RRC connection reconstruction (RRE) procedure is performed to recover from radio link problems and a specific operation fails (720). The following situations may occur as reasons for initiating the above-mentioned RRC connection reconstruction procedure.

[0152] - First cause: Radio link failure (RLF) detected in the MCG (without Fast MCG recovery configured).

[0153] - Second reason: A situation where synchronous reconfiguration fails in MCG.

[0154] - Third reason: Mobility failures from NR

[0155] - Fourth reason: The case where an integrity check failure indication is received from a lower layer (except when an integrity check failure is detected in the RRCReconfiguration message).

[0156] Fifth reason: RRC connection reconfiguration failure

[0157] - Sixth reason: When MCG transmission is paused while RLF is detected in SCG (NR-DC or NE-DC)

[0158] - Seventh reason: MCG transmission is paused while synchronous reconfiguration fails.

[0159] - Eighth reason: SCG change fails while MCG transmission is paused (NE-DC)

[0160] - Ninth reason: SCG configuration failure during MCG transmission suspension (NR-DC or NE-DC)

[0161] - Tenth reason: When MCG transmission is paused while an integrity check failure indication of SRB3 is received from a lower layer.

[0162] - Eleventh reason: T316 has expired.

[0163] As an explanation of T316, Table 1 below represents the protection timer between the transmission of the MCG failure message and the execution of the next operation. The corresponding timer can terminate if the MCG transmission resumes before the corresponding timer expires, if the RRC Reset message is received, or if the RRC reconstruction process begins. If the corresponding timer has expired, the UE can begin the reconstruction process.

[0164] [Table 1]

[0165]

[0166] During an RRC connection re-establishment process caused by the aforementioned reasons, the UE may perform cell selection, MAC reset, radio bearer (RB) suspension, or PDCP re-establishment. Furthermore, upon the start of the RRC connection re-establishment process, the UE operates a T311 timer, and during the timer's operation, no radio link recovery operation is performed. If RRC connection re-establishment is not performed during the timer's operation, and then the timer expires, the UE may transition to an RRC idle state. In step 725, this disclosure proposes an operation to discard segmented RRC messages stored in the UE's RRC layer by distinguishing the reasons for the additional triggering of the RRC connection re-establishment, even though an RRC connection re-establishment process has been performed for the aforementioned reasons, and for this purpose, a PDCP re-establishment operation has been performed. The discarded segmented RRC messages may correspond to downlink segmented RRC messages, uplink segmented RRC messages, or both. As an example, RRC messages not transmitted to the PDCP layer but stored in the RRC layer may be discarded. Furthermore, the base station may discard segmented RRC messages stored in the RRC layer in the same manner as the UE in the corresponding operation.

[0167] Figure 8 This diagram illustrates UE operations for processing downlink segmented RRC messages for each event when an event related to RRC reconstruction occurs, as a first embodiment of this disclosure.

[0168] In step 805, the UE performs an RRC connection procedure with the serving base station and reports its supported capabilities to the corresponding base station. Specifically, in step 810, the UE can receive a request for reporting UE capability information (UECapabilityEnquiry message) from the base station, and this message may include filtering information for the UE capability information (RAT type or frequency information). If the UECapabilityEnquiry message is received, the UE stores and transmits the UE capability information, and specifically, in this disclosure, may include an indicator indicating whether downlink RRC message segments are supported. This can be transmitted using one bit as signaling for the entire UE capability, or one bit can be included for each RAT type. By receiving the corresponding indicator, the base station can identify that the corresponding UE can receive and resume downlink segmented RRC messages.

[0169] In operation 815, the UE can receive downlink segmented RRC messages (DLDedicatedMessageSegment) from the base station, in which RRCReconfiguration messages or RRCResume messages are segmented. In step 820, if RRC reconstruction occurs due to a specific event while the RRC segmented message has been received but not the segmented RRC message corresponding to the last segmentation indicator, the UE can perform different operations on the corresponding operation. That is, RRC reconstruction may occur due to the above reference... Figure 7 The events described above occur due to certain reasons, and the UE's operation may vary depending on the cause of the event. The operation defined in this disclosure refers to whether to discard segments of downlink or uplink RRC messages stored in the UE's RRC layer when a corresponding RRC reconstruction occurs. Even though an RRC reconstruction has occurred for the corresponding reason, the corresponding link can be reused under certain circumstances, and therefore the RRC segments stored in the RRC layer can be stored without discarding them. As another example, if an RRC reconstruction occurs, the corresponding link is initialized, and therefore it is necessary to discard all RRC segments stored in the RRC layer.

[0170] Table 2 below outlines the operations on the UE RRC layer due to the occurrence of RRC reconstruction (RRE).

[0171] [Table 2]

[0172]

[0173]

[0174] At step 820, the UE may perform an RRC reconstruction procedure for the reasons arranged in Table 2 above, and as the initial UE operation for the corresponding procedure, the UE may determine whether to discard or retain the RRC segment for each reason. The UE operation for each reason is referenced in Table 2 above. It can be assumed that the reason for discarding the RRC segment is defined as event 1, and the reason for not discarding the RRC segment is defined as event 2. In the case of event 1 as the reason for the RRE procedure, at step 825, the UE may discard the received DL segment at the initial UE operation while performing the RRC reconstruction procedure at the RRC layer, thereby receiving a new RRC control message via SRB1. Conversely, in the case of event 2 as the reason for the RRE procedure, at operation 830, the UE may perform the RRC reconstruction procedure without discarding the received DL segment. That is, the UE may retain the DL segment stored at the RRC layer and then reuse the aforementioned DL segment in a message. As an example, since the corresponding stored RRC segments have their own sequence numbers, segments following previously transmitted segments can be transmitted over the network, and the UE can distinguish this. Furthermore, the same operation can be applied to all reasons that trigger the RRC rebuild process. In this case, regardless of the reason for triggering the RRC rebuild process, all RRC segment messages stored at the RRC layer are discarded. Figure 9 This diagram illustrates the UE operations for processing downlink segmented RRC messages for each event when an event related to RRC reconstruction occurs, in a state where the primary cell group (MCG) fast recovery is configured, as a second embodiment of this disclosure.

[0175] Normally, when an RLF occurs in the MCG, an RRC reconstruction operation is performed. However, if MCG fast recovery is configured, and data transmission / reception through the SCG path is determined to be smooth, data transmission / reception can be performed through the SCG path even when an RLF occurs in the MCG, instead of performing an RRC reconstruction.

[0176] In step 905, the UE performs an RRC connection procedure with the serving base station and reports its supported capabilities to the corresponding base station. That is, in operation 910, the UE can receive a request for a report of its UE capability information (UECapabilityEnquiry message) from the base station, and this message may include filtering information for the UE capability information (RAT type or frequency information). If the UECapabilityEnquiry message is received, the UE stores and transmits the UE capability information, and, particularly in this disclosure, may include an indicator indicating whether downlink RRC message segments are supported. This can be transmitted using one bit as signaling for the entire UE capability, or one bit can be included for each RAT type. By receiving the corresponding indicator, the base station can identify that the corresponding UE can receive and resume downlink segmented RRC messages.

[0177] In step 915, the UE can receive a downlink segmented RRC message (DLDedicatedMessageSegment) from the base station, which is segmented into either an RRCReconfiguration message or an RRCResume message. In step 920, if RRC reconstruction occurs due to a specific event while the UE has received the RRC segmented message but not the segmented RRC message corresponding to the last segmentation indicator, the UE can perform different operations accordingly. That is, RRC reconstruction may occur due to the above reference... Figure 7 The events described above occur due to certain reasons, and the UE's operation may vary depending on the cause of the event. The operation defined in this disclosure refers to whether to discard segments of downlink or uplink RRC messages stored in the UE's RRC layer when a corresponding RRC reconstruction occurs. Even though an RRC reconstruction has occurred for the corresponding reason, the corresponding link can be reused under certain circumstances, and therefore the RRC segments stored in the RRC layer can be stored without discarding them. As another example, if an RRC reconstruction occurs, the corresponding link is initialized, and therefore it is necessary to discard all RRC segments stored in the RRC layer.

[0178] Specifically, the second embodiment specifies UE operation in a state configured with MCG fast recovery, and can correspond to reasons 6, 7, 8, and 9 among the causes of RRE occurrence. UE operation and Figure 8 The difference in operation is that when reasons 6, 7, 8 and 9 occur in the corresponding MCG pause state, the case where the MCG pause is resumed has been taken into account, and in this case, the stored RRC segments need to be maintained because the links to the MCG can be reused.

[0179] In step 920, if the MCG RLF occurs before the UE receives the last segment and causes 6, 7, 8, and 9 as arranged in Table 2 above occur, the UE operation can be different. If the existing MCG RLF occurs and the MCG failure procedure is triggered, defined as event 3, and event 3 occurs, then in step 925, the UE can discard the DL segment as the UE's initial operation during the RRC reconstruction procedure on the RRC, thereby receiving a new RRC control message via SRB1. This operation is consistent with the above-mentioned... Figure 8 The operations described in reasons 6, 7, 8, and 9 are the same. Conversely, if we assume that fast MCG recovery is configured in the existing MCG RLF occurrence event and the PSCell change is not in progress and SCG transmission is not paused, and the MCG link is restored in event 4, then in step 930, when event 4 occurs, the UE can perform the RRC reconstruction procedure without discarding the received DL segments. That is, the DL segments stored in the RRC layer can be retained and then reused in messages. As an example, since the stored RRC segments have their own sequence numbers, the remaining segments after the previously sent segments can be transmitted over the network, and the UE can distinguish this.

[0180] Figure 10 This is a diagram illustrating the operation of a base station according to an embodiment of the present disclosure.

[0181] In step 1005, the serving base station (eNB or gNB) can establish a connection with the UE, and during this operation, the DC can be configured, and the MN and SN can be connected to the UE. In step 1010, the base station can determine to transmit an RRCReconfiguration message to the UE and can generate corresponding information. Figure 10 In the state of dual connectivity (hereinafter referred to as "DC") as shown, the following may occur depending on how the RRCReconfiguration message is transmitted.

[0182] -Scenario 1: When the master node (MN) generates an RRC message that includes MCG configuration information, the base station can transmit the generated RRC message through SRB1.

[0183] -Scenario 2: When the MN has transmitted the secondary node (SN) configuration information and generated an RRC message including MCG / SCG configuration information, the base station can transmit the generated RRC message through SRB1.

[0184] -Scenario 3: When the SN generates an RRC message that includes SCG configuration information, the base station can transmit the generated RRC message through SRB3.

[0185] In step 1015, the base station can identify whether the RRC control message generated in step 1010 exceeds 9000 bytes (1020), which corresponds to the maximum size of the PDCPSDU. If the size of the generated RRC message exceeds 9000 bytes, then in step 1025, the base station can identify whether the corresponding message was generated from the MN or the SN. In the case where the message is generated from the MN, in operation 1030, the base station can generate and store segmented RRCReconfiguration messages in a DLDedicatedMessageSegment, and can transmit multiple DLDedicatedMessageSegment messages containing all complete RRCReconfiguration messages to SRB1. In this case, messages can be transmitted sequentially through SRB1 without interrupting another DL RRC message. If, as a result of identifying the message generation node in operation 1025, the message is generated from the SN (i.e., if the message is an RRC message of the SN and SRB3 is configured), then in step 1040, the base station can store and generate segmented RRCReconfiguration messages in DLDedicatedMessageSegment, and then multiple DLDedicatedMessageSegments containing all complete RRCReconfiguration messages can be transmitted to SRB3. In this case, messages can be transmitted sequentially through SRB3 without interrupting another DL RRC message.

[0186] If the size of the downlink RRC message generated in step 1020 is less than 9000 bytes, the base station can transmit the generated RRC message by generating the corresponding message's SRB. Subsequently, in step 1055, data transmission / reception can be performed based on information configured with the UE.

[0187] Figure 11 This is a diagram illustrating the block configuration of a UE according to an embodiment of the present disclosure.

[0188] like Figure 11 As shown, a terminal according to an embodiment of this disclosure may include a transceiver 1105, a controller 1110, a multiplexer / demultiplexer 1115, various higher-level processors 1120 and 1125, and a control message processor 1130.

[0189] Transceiver 1105 can receive data and specific control signals on the forward channel of the serving cell and can transmit data and specific control signals on the backward channel. If multiple serving cells are configured, transceiver 1105 can perform data and control signal transmission and reception through multiple serving cells. Multiplexer / demultiplexer 1115 can be used to multiplex data generated by higher-layer processors 1120 and 1125 or control message processor 1130, demultiplex data received by transceiver 1105, and appropriately transmit multiplexed or demultiplexed data to higher-layer processors 1120 and 1125 or control message processor 1130. Control message processor 1130 can take necessary operations by sending and receiving control messages from the base station. Here, control message processor may include functions for processing control messages such as RRC messages and MAC CE, functions for reporting CBR measurement values, and functions for receiving RRC messages for resource pool and terminal operations. Higher-layer processors 1120 or 1125 mean DRB devices and can be configured for each service. Higher-level processors can process data generated through user services (such as File Transfer Protocol (FTP) or Voice over Internet Protocol (VoIP)) and can transmit processed data to multiplexer / demultiplexer 1115, or process data transmitted from multiplexer / demultiplexer 1115 and transmit processed data to higher-level service applications. Controller 1110 can control transceiver 1105 and multiplexer / demultiplexer 1115 to identify scheduling commands received through transceiver 1105, such as backward authorization, and perform backward transmission as appropriate transmission resources at the appropriate time. On the other hand, although a terminal has been described as consisting of multiple blocks that perform different functions, this is merely exemplary and the embodiment is not limited thereto. For example, controller 1110 can perform the functions performed by demultiplexer 1115.

[0190] Figure 12 This is a diagram illustrating the block configuration of a base station according to an embodiment of the present disclosure.

[0191] Figure 12 The base station may include a transceiver 1205, a controller 1210, a multiplexer / demultiplexer 1220, a control message processor 1235, various higher-level processors 1225 and 1230, and a scheduler 1215.

[0192] Transceiver 1205 can transmit data and specific control signals on the forward carrier and receive data and specific control signals on the backward carrier. Multiplexer / demultiplexer 1220 can be used to multiplex data generated by higher-level processors 1225 and 1230 or control message processor 1235, demultiplex data received by transceiver 1205, and appropriately transmit the multiplexed or demultiplexed data to higher-level processors 1225 and 1230, control message processor 1235, or controller 1210. Control message processor 1235 can generate messages to be transmitted to terminals and can transmit the generated messages to lower layers. Higher-level processors 1225 and 1230 can be configured for each terminal and each service. Higher-level processors 1225 and 1230 can process data generated in user services (e.g., FTP or VoIP) and transmit the generated data to multiplexer / demultiplexer 1220, or they can process data transmitted from multiplexer / demultiplexer 1220 and transmit the processed data to higher-level service applications. Scheduler 1215 can allocate transmission resources to terminals at appropriate times, taking into account terminal buffer states, channel states, and terminal activity times; it can process signals sent from terminals to transceivers, or it can send signals to terminals.

[0193] In the detailed embodiments described above, elements included in this disclosure may be represented in either a singular or plural form according to the proposed detailed embodiments. However, for ease of description, singular or plural expressions have been suitably chosen for the proposed situations, and this disclosure is not limited to singular or plural elements. Although an element is expressed in a plural form, it may also be configured in a singular form. Although an element is expressed in a singular form, it may also be configured in a plural form. While the embodiments described in this specification have been described individually, two or more embodiments may be combined and practiced.

[0194] Although detailed embodiments have been described in the detailed description of this disclosure, this disclosure can be modified in various ways without departing from its scope. Therefore, the scope of this disclosure should not be limited to the above embodiments, but should be defined not only by the claims, but also by their equivalents.

Claims

1. A method performed by a user equipment (UE) in a wireless communication system, the method comprising: The segments received from the base station are segmented Radio Resource Control (RRC) messages. Identify whether an RRC reconstruction (RRE) occurred before the last segment of the segmented RRC message was received; as well as If the RRE occurs before the last segment of the segmented RRC message is received, determine whether to discard or retain the received segment of the segmented RRC message based on the cause of the RRE. In the event of a failure of the primary cell group MCG integrity protection IP check in either Signalling Radio Bearer 1 SRB1 or Signalling Radio Bearer 2 SRB2, the received segments of the segmented RRC message are discarded, and In the event of an IP check failure in Signaling Radio Bearer 3 (SRB3), the received segments of the segmented RRC message are retained.

2. The method according to claim 1, wherein, In the event of an RRE failure, a Radio Link Failure (RLF) in the secondary cell group (SCG), an SCG reconfiguration failure with synchronization, an SCG reconstruction failure, or an SCG integrity protection check failure, the received segments of the segmented RRC message are discarded.

3. The method according to claim 1, wherein, In the event of a failed MCG reconfiguration with synchronization or a mobility failure from a new radio NR, the received segments of the segmented RRC message are retained.

4. The method according to claim 1, further comprising: Receive a UE capability query message from the base station; as well as Based on the UE capability query message, UE capability information is sent to the base station. The UE capability information includes an indicator indicating whether the UE supports the segmented RRC message.

5. A method performed by a base station in a wireless communication system, the method comprising: Send a UE capability query message to the user equipment (UE); Based on the UE capability query message, UE capability information is received from the UE, the UE capability information including an indicator indicating whether the UE supports segmented radio resource control (RRC) messages; as well as The segment of the segmented RRC message is sent to the UE. In the case where an RRC reconstruction (RRE) occurs before the last segment of the segmented RRC message is sent, whether to discard or retain the sent segment of the segmented RRC message is determined based on the cause of the RRE. In the event of a failure of the primary cell group (MCG) integrity protection IP check in either Signalling Radio Bearer 1 (SRB1) or Signalling Radio Bearer 2 (SRB2), the transmitted segment of the segmented RRC message is discarded, and In the event of an IP check failure in Signaling Radio Bearer 3 (SRB3), the transmitted segments of the segmented RRC message are preserved.

6. The method according to claim 5, wherein, In the event of an RRE failure, a Radio Link Failure (RLF) in the secondary cell group (SCG), an SCG reconfiguration failure with synchronization, an SCG reconstruction failure, or an SCG integrity protection check failure, the transmitted segment of the segmented RRC message is discarded.

7. The method according to claim 5, wherein, In the event of a failed MCG reconfiguration with synchronization or a mobility failure from a new radio NR, the transmitted segments of the segmented RRC message are preserved.

8. A user equipment (UE) in a wireless communication system, the UE comprising: transceiver; as well as A controller, coupled to the transceiver, is configured to: The segments received from the base station via segmented Radio Resource Control (RRC) messages. Identify whether an RRC reconstruction (RRE) occurred before the last segment of the segmented RRC message was received, and If the RRE occurs before the last segment of the segmented RRC message is received, the received segment of the segmented RRC message is determined based on the cause of the RRE, whether to discard or retain the received segment of the segmented RRC message. In the event of a failure of the primary cell group MCG integrity protection IP check in either Signalling Radio Bearer 1 SRB1 or Signalling Radio Bearer 2 SRB2, the received segments of the segmented RRC message are discarded, and In the event of an IP check failure in Signaling Radio Bearer 3 (SRB3), the received segments of the segmented RRC message are retained.

9. The UE according to claim 8, wherein, In the event of an RRE failure, a Radio Link Failure (RLF) in the secondary cell group (SCG), an SCG reconfiguration failure with synchronization, an SCG reconstruction failure, or an SCG integrity protection check failure, the received segments of the segmented RRC message are discarded.

10. The UE of claim 8, wherein, In the event of a failed MCG reconfiguration with synchronization or a mobility failure from a new radio NR, the received segments of the segmented RRC message are retained.

11. The UE according to claim 8, wherein, The controller is further configured to: Receive a UE capability query message from the base station; as well as Based on the UE capability query message, UE capability information is sent to the base station. The UE capability information includes an indicator indicating whether the UE supports the segmented RRC message.

12. A base station in a wireless communication system, the base station comprising: transceiver; as well as A controller, coupled to the transceiver, is configured to: Send a UE capability query message to the user equipment (UE). Based on the UE capability query message, UE capability information is received from the UE. This UE capability information includes an indicator showing whether the UE supports Segmented Radio Resource Control (RRC) messages, and... The segment of the segmented RRC message is sent to the UE. In the case where an RRC reconstruction (RRE) occurs before the last segment of the segmented RRC message is sent, whether to discard or retain the sent segment of the segmented RRC message is determined based on the cause of the RRE. In the event of a failure of the primary cell group (MCG) integrity protection IP check in either Signalling Radio Bearer 1 (SRB1) or Signalling Radio Bearer 2 (SRB2), the transmitted segment of the segmented RRC message is discarded, and In the event of an IP check failure in Signaling Radio Bearer 3 (SRB3), the transmitted segments of the segmented RRC message are preserved.

13. The base station according to claim 12, wherein, In the event of an RRE failure, a Radio Link Failure (RLF) in the secondary cell group (SCG), an SCG reconfiguration failure with synchronization, an SCG reconstruction failure, or an SCG integrity protection check failure, the transmitted segment of the segmented RRC message is discarded.

14. The base station according to claim 12, wherein, In the event of a failed MCG reconfiguration with synchronization or a mobility failure from a new radio NR, the transmitted segments of the segmented RRC message are preserved.

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