KR20240019000A - Method and apparatus for handling group mobility within mobile integrated access and backhaul node cell in wireless communication system - Google Patents

Abstract

This disclosure relates to 5G or 6G communication systems to support higher data rates. The present disclosure relates to a method and device for processing cell change of a terminal with respect to an Integrated Access and Backhaul (IAB) node in a wireless communication system. The present disclosure includes the steps of receiving an RRCReconfiguration message from a source node and a message containing configuration information to be used in a target cell operated by a target node, based on the received configuration information, transmitting the RRCReconfiguration message to a target cell, the target When the random access procedure of the terminal to the cell is successful, receiving an RRCReconfigurationComplete message from the target cell, and transmitting a message requesting termination of operation of the cell operated by the source node based on the received RRCReconfigurationComplete message. Discloses a method performed by an IAB node in a wireless communication system.

Description

Method and apparatus for processing group mobility of mobile integrated access and backhaul node cells in a wireless communication system {METHOD AND APPARATUS FOR HANDLING GROUP MOBILITY WITHIN MOBILE INTEGRATED ACCESS AND BACKHAUL NODE CELL IN WIRELESS COMMUNICATION SYSTEM}

This disclosure relates to the operation of a terminal in a wireless communication system. Specifically, it relates to a method and device for processing a cell change of a terminal with respect to an Integrated Access and Backhaul (IAB) node in a wireless communication system.

5G mobile communication technology defines a wide frequency band to enable fast transmission speeds and new services, and includes sub-6 GHz ('Sub 6GHz') bands such as 3.5 gigahertz (3.5 GHz) as well as millimeter wave (mm) bands such as 28 GHz and 39 GHz. It is also possible to implement it in the ultra-high frequency band ('Above 6GHz') called Wave. In addition, in the case of 6G mobile communication technology, which is called the system of Beyond 5G, Terra is working to achieve a transmission speed that is 50 times faster than 5G mobile communication technology and an ultra-low delay time that is reduced to one-tenth. Implementation in Terahertz bands (e.g., 95 GHz to 3 THz) is being considered.

In the early days of 5G mobile communication technology, there were concerns about ultra-wideband services (enhanced Mobile BroadBand, eMBB), ultra-reliable low-latency communications (URLLC), and massive machine-type communications (mMTC). With the goal of satisfying service support and performance requirements, efficient use of ultra-high frequency resources, including beamforming and massive array multiple input/output (Massive MIMO) to alleviate radio wave path loss in ultra-high frequency bands and increase radio transmission distance. Various numerology support (multiple subcarrier interval operation, etc.) and dynamic operation of slot format, initial access technology to support multi-beam transmission and broadband, definition and operation of BWP (Band-Width Part), large capacity New channel coding methods such as LDPC (Low Density Parity Check) codes for data transmission and Polar Code for highly reliable transmission of control information, L2 pre-processing, and dedicated services specialized for specific services. Standardization of network slicing, etc., which provides networks, has been carried out.

Currently, discussions are underway to improve and enhance the initial 5G mobile communication technology, considering the services that 5G mobile communication technology was intended to support, based on the vehicle's own location and status information. V2X (Vehicle-to-Everything) to help autonomous vehicles make driving decisions and increase user convenience, and NR-U (New Radio Unlicensed), which aims to operate a system that meets various regulatory requirements in unlicensed bands. ), NR terminal low power consumption technology (UE Power Saving), Non-Terrestrial Network (NTN), which is direct terminal-satellite communication to secure coverage in areas where communication with the terrestrial network is impossible, positioning, etc. Physical layer standardization for technology is in progress.

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

When this 5G mobile communication system is commercialized, an explosive increase in connected devices will be connected to the communication network. Accordingly, it is expected that strengthening the functions and performance of the 5G mobile communication system and integrated operation of connected devices will be necessary. To this end, eXtended Reality (XR) and Artificial Intelligence are designed to efficiently support Augmented Reality (AR), Virtual Reality (VR), and Mixed Reality (MR). , AI) and machine learning (ML), new research will be conducted on 5G performance improvement and complexity reduction, AI service support, metaverse service support, and drone communication.

In addition, the development of these 5G mobile communication systems includes new waveforms, full dimensional MIMO (FD-MIMO), and array antennas to ensure coverage in the terahertz band of 6G mobile communication technology. , multi-antenna transmission technology such as Large Scale Antenna, metamaterial-based lens and antenna to improve coverage of terahertz band signals, high-dimensional spatial multiplexing technology using OAM (Orbital Angular Momentum), RIS ( In addition to Reconfigurable Intelligent Surface technology, Full Duplex technology, satellite, and AI (Artificial Intelligence) to improve the frequency efficiency of 6G mobile communication technology and system network are utilized from the design stage and end-to-end. -to-End) Development of AI-based communication technology that realizes system optimization by internalizing AI support functions, and next-generation distributed computing technology that realizes services of complexity beyond the limits of terminal computing capabilities by utilizing ultra-high-performance communication and computing resources. It could be the basis for .

As various services can be provided as described above and with the development of mobile communication systems, there is a need for a method to effectively provide these services.

The disclosed embodiment seeks to provide a method and device that can effectively handle a terminal cell change due to a donor node change when an integrated access and backhaul node moves in a wireless communication system.

According to the present disclosure, in a method performed by an integrated access and backhaul (IAB) node in a wireless communication system, the method includes receiving an RRCReconfiguration message from a source node and configuration information to be used in a target cell operated by a target node. Receiving a message including, based on the received configuration information, transmitting the RRCReconfiguration message to a target cell, if the random access procedure of the terminal to the target cell is successful, receiving an RRCReconfigurationComplete message from the target cell and transmitting a message requesting termination of operation of a cell operated by the source node based on the received RRCReconfigurationComplete message.

Various embodiments of the present disclosure provide methods and devices that can effectively derive location information of a terminal in a wireless communication system.

1 is a diagram illustrating the structure of an LTE system according to an embodiment of the present disclosure.
Figure 2 is a diagram showing the wireless protocol structure of an LTE system according to an embodiment of the present disclosure.
Figure 3 is a diagram showing the structure of a next-generation mobile communication system according to an embodiment of the present disclosure.
Figure 4 is a diagram showing the wireless protocol structure of a next-generation mobile communication system according to an embodiment of the present disclosure.
Figure 5 is a block diagram showing the structure of a terminal according to an embodiment of the present disclosure.
Figure 6 is a block diagram showing the structure of an NR base station according to an embodiment of the present disclosure.
FIG. 7 is a diagram illustrating cell creation and cell connection operations of a terminal according to movement of a mobile IAB node according to an embodiment of the present disclosure.
FIG. 8 is a flowchart illustrating an operation in which a mobile IAB node stores a handover command of a terminal and then transmits the handover command to the terminal after a new cell is operated, according to an embodiment of the present disclosure.
FIG. 9 is a flowchart illustrating an operation in which handover of a UE is performed when the target donor can store the HO command message of the access UE according to an embodiment of the present disclosure.
FIG. 10 is a flowchart illustrating an operation in which handover of a UE is performed when conditional handover is applied to an access UE according to an embodiment of the present disclosure.

Hereinafter, the operating principle of the present disclosure will be described in detail with reference to the attached drawings. In the following description of the present disclosure, if a detailed description of a related known function or configuration is determined to unnecessarily obscure the gist of the present disclosure, the detailed description will be omitted. In addition, the terms described below are terms defined in consideration of the functions in the present disclosure, and may vary depending on the intention or custom of the user or operator. Therefore, the definition should be made based on the contents throughout this specification.

Terms used in the following description to identify a connection node, a term referring to network entities, a term referring to messages, a term referring to an interface between network objects, and a term referring to various types of identification information. The following are examples for convenience of explanation. Accordingly, the present disclosure is not limited to the terms described below, and other terms referring to objects having equivalent technical meaning may be used.

Hereinafter, the base station is the entity that performs resource allocation for the terminal and may be at least one of gNode B, eNode B, Node B, BS (Base Station), wireless access unit, base station controller, or node on the network. A terminal may include a user equipment (UE), a mobile station (MS), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing communication functions. In this disclosure, downlink (DL) refers to a wireless transmission path of a signal transmitted from a base station to a terminal, and uplink (UL) refers to a wireless transmission path of a signal transmitted from a terminal to a base station. In addition, although the LTE or LTE-A system may be described below as an example, embodiments of the present disclosure can also be applied to other communication systems with similar technical background or channel types. For example, the 5th generation mobile communication technology (5G, new radio, NR) developed after LTE-A may be included in a system to which embodiments of the present disclosure can be applied, and 5G hereinafter refers to existing LTE, LTE-A, and It may be a concept that includes other similar services. In addition, this disclosure may be applied to other communication systems through some modifications without significantly departing from the scope of the present disclosure at the discretion of a person with skilled technical knowledge. At this time, it will be understood that each block of the processing flow diagram diagrams and combinations of the flow diagram diagrams can be performed by computer program instructions.

These computer program instructions can be mounted on a processor of a general-purpose computer, special-purpose computer, or other programmable data processing equipment, so that the instructions performed through the processor of the computer or other programmable data processing equipment are described in the flow chart block(s). It creates the means to perform functions. These computer program instructions may also be stored in computer-usable or computer-readable memory that can be directed to a computer or other programmable data processing equipment to implement a function in a particular manner, so that the computer-usable or computer-readable memory It is also possible to produce manufactured items containing instruction means that perform the functions described in the flowchart block(s). Computer program instructions can also be mounted on a computer or other programmable data processing equipment, so that a series of operational steps are performed on the computer or other programmable data processing equipment to create a process that is executed by the computer, thereby generating a process that is executed by the computer or other programmable data processing equipment. Instructions that perform processing equipment may also provide steps for executing the functions described in the flow diagram block(s).

Additionally, each block may represent a module, segment, or portion of code that includes one or more executable instructions for executing specified logical function(s). Additionally, it should be noted that in some alternative execution examples it is possible for the functions mentioned in the blocks to occur out of order. For example, it is possible for two blocks shown in succession to be performed substantially simultaneously, or it is possible for the blocks to be performed in reverse order depending on the corresponding function. At this time, the term '~unit' used in this embodiment refers to software or hardware components such as FPGA (Field Programmable Gate Array) or ASIC (Application Specific Integrated Circuit), and '~unit' refers to what roles. It can be done. However, '~part' is not limited to software or hardware. The '~ part' may be configured to reside in an addressable storage medium and may be configured to reproduce on one or more processors. Therefore, as an example, '~ part' refers to components such as software components, object-oriented software components, class components, and task components, processes, functions, properties, and procedures. , subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. The functions provided within the components and 'parts' may be combined into a smaller number of components and 'parts' or may be further separated into additional components and 'parts'. Additionally, components and 'parts' may be implemented to regenerate one or more CPUs within a device or a secure multimedia card. Also, in an embodiment, '~ part' may include one or more processors.

For convenience of description below, this disclosure uses terms and names defined in the 5GS and NR standards, which are standards defined by the 3rd Generation Partnership Project (3GPP) organization among currently existing communication standards. However, the present disclosure is not limited by the above terms and names, and can be equally applied to wireless communication networks complying with other standards. For example, the present disclosure can be applied to 3GPP 5GS/NR (5th generation mobile communication standard).

When the backhaul access hole combining node moves, a cell change operation of the terminal is required due to a change in the donor node. There is a difference between the time when the target donor node performs admission control of the terminals and the time when the terminal applies the settings in the given target cell. There may be, and procedures for this are necessary. Additionally, when multiple terminals perform handover operations, collisions in random access and congestion of UL/DL resources may occur, so it is necessary to separate HO operations of terminals in time.

After successful migration of the Mobile IAB node, the target donor node can instruct the DU of the mobile IAB node to operate a new cell, and after successful execution of this instruction, the access UE can perform a handover to this new cell. For this purpose, a method can be used in which the mobile IAB node stores the handover command to the target cell for the access UE and then transmits it after a new cell is established.

According to various embodiments of the present disclosure, access UEs can perform stable network communication even under the mobility of the IAB node.

FIG. 1 is a diagram illustrating the structure of an LTE system according to an embodiment of the present disclosure.

Referring to FIG. 1, as shown, the wireless access network of the LTE system includes a next-generation base station (Evolved Node B, hereinafter referred to as ENB, Node B or base station) (1-05, 1-10, 1-15, 1-20) and It may be composed of a Mobility Management Entity (MME) (1-25) and S-GW (1-30, Serving-Gateway). User equipment (hereinafter referred to as UE or terminal) (1-35) can access an external network through ENB (1-05 to 1-20) and S-GW (1-30).

In FIG. 1, ENBs 1-05 to 1-20 may correspond to the existing Node B of the Universal Mobile Telecommunication System (UMTS) system. The ENB is connected to the UE (1-35) through a wireless channel and can perform a more complex role than the existing Node B. In an LTE system, all user traffic, including real-time services such as VoIP (Voice over IP) through the Internet Protocol, can be serviced through a shared channel. Therefore, a device is needed to perform scheduling by collecting status information such as buffer status, available transmission power status, and channel status of UEs, and ENBs 1-05 to 1-20 can be responsible for this. One ENB can usually control multiple cells. For example, in order to implement a transmission speed of 100 Mbps, the LTE system can use Orthogonal Frequency Division Multiplexing (OFDM) as a wireless access technology in a 20 MHz bandwidth. Of course, it is not limited to the above example. In addition, ENB (1-05 to 1-20) applies an Adaptive Modulation & Coding (AMC) method that determines the modulation scheme and channel coding rate according to the channel status of the terminal. can do. The S-GW (1-30) is a device that provides data bearers, and can create or remove data bearers under the control of the MME (1-25). The MME is a device that handles various control functions as well as mobility management functions for the terminal and can be connected to multiple base stations.

Figure 2 is a diagram showing the wireless protocol structure of an LTE system according to an embodiment of the present disclosure.

Referring to Figure 2, the wireless protocols of the LTE system are Packet Data Convergence Protocol (PDCP) (2-05, 2-40) and Radio Link Control (RLC) (Radio Link Control, RLC) in the terminal and ENB, respectively. 2-10, 2-35), Medium Access Control (MAC) (2-15, 2-30), and Physical (PHY) (2-20, 2-25) layers. . Of course, the wireless protocol of the LTE system may consist of more or fewer layers than the configuration shown in FIG. 2.

According to an embodiment of the present disclosure, PDCP (2-05, 2-40) may be responsible for operations such as IP header compression/restoration. The main functions of PDCP (2-05, 2-40) can be summarized as follows. Of course, this is not limited to the examples below.

- Header compression and decompression: ROHC (Robust Header Compression) only

- Transfer of user data

- In-sequence delivery of upper layer PDUs at PDCP re-establishment procedure for RLC AM (Acknowledge Mode)

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

- Duplicate detection of lower layer SDUs at PDCP re-establishment procedure for RLC AM

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

- Encryption and decryption function (Ciphering and deciphering)

- Timer-based SDU discard in uplink.

According to an embodiment of the present disclosure, Radio Link Control (RLC) (2-10, 2-35) reconfigures the PDCP Packet Data Unit (PDU) to an appropriate size to perform ARQ operation, etc. It can be done. The main functions of RLC can be summarized as follows. Of course, it is not limited to the examples below.

- Data transfer function (Transfer of upper layer PDUs)

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

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

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

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

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

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

- RLC SDU deletion function (RLC SDU discard (only for UM and AM data transfer))

- RLC re-establishment function

According to an embodiment of the present disclosure, MAC (2-15, 2-30) is connected to several RLC layer devices configured in one terminal, multiplexes RLC PDUs to MAC PDUs and demultiplexes RLC PDUs from MAC PDUs. The action can be performed. The main functions of MAC (2-15, 2-30) can be summarized as follows. Of course, this is not limited to the examples below.

- Mapping function (Mapping between logical channels and transport channels)

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

- Scheduling information reporting

- HARQ function (Error correction through HARQ)

- Priority handling between logical channels of one UE

- Priority handling between UEs by means of dynamic scheduling

- MBMS service identification function

- Transport format selection function

- Padding function

According to an embodiment of the present disclosure, the physical layer (2-20, 2-25) channel codes and modulates the upper layer data, creates an OFDM symbol and transmits it over a wireless channel, or converts the OFDM symbol received through the wireless channel into an OFDM symbol. You can demodulate, decode the channel, and transmit it to the upper layer. Of course, this is not limited to the examples below.

Figure 3 is a diagram showing the structure of a next-generation mobile communication system according to an embodiment of the present disclosure.

Referring to Figure 3, the radio access network of the next-generation mobile communication system (hereinafter referred to as NR or 5G) includes a next-generation base station (New Radio Node B, hereinafter referred to as NR gNB or NR base station) (3-10) and a next-generation wireless core network (New Radio Core). Network, NR CN) (3-05). The next-generation wireless user equipment (New Radio User Equipment, NR UE or UE) (3-15) can access an external network through NR gNB (3-10) and NR CN (3-05).

In Figure 3, NR gNB (3-10) may correspond to an eNB (Evolved Node B) of the existing LTE system. NR gNB is connected to NR UE (3-15) through a wireless channel and can provide superior services than the existing Node B. In the next-generation mobile communication system, all user traffic can be serviced through a shared channel. Therefore, a device may be needed to perform scheduling by collecting status information such as buffer status, available transmission power status, and channel status of UEs, and the NR NB 3-10 may be responsible for the scheduling. One NR gNB can control multiple cells.

According to an embodiment of the present disclosure, in a next-generation mobile communication system, a bandwidth greater than the general maximum bandwidth may be applied to implement ultra-high-speed data transmission compared to general LTE. Additionally, beamforming technology may be additionally used using Orthogonal Frequency Division Multiplexing (OFDM) as a wireless access technology.

According to an embodiment of the present disclosure, NR gNB uses Adaptive Modulation & Coding (hereinafter referred to as AMC) to determine the modulation scheme and channel coding rate according to the channel status of the terminal. method can be applied. NR CN (3-05) can perform functions such as mobility support, bearer setup, and QoS (Quality of Service) setup. NR CN (3-05) is a device that handles various control functions as well as mobility management functions for the terminal and can be connected to multiple base stations. Additionally, the next-generation mobile communication system can be linked to the LTE system, and NR CN (3-05) can be connected to MME (3-25) through a network interface. MME (3-25) can be connected to eNB (3-30), which is an LTE base station.

Figure 4 is a diagram showing the wireless protocol structure of a next-generation mobile communication system according to an embodiment of the present disclosure.

Referring to FIG. 4, the wireless protocols of the next-generation mobile communication system are NR Service Data Adaptation Protocol (SDAP) (4-01, 4-45) and NR PDCP (4-05, 4-05) in the terminal and NR base station, respectively. 4-40), NR RLC (4-10, 4-35), NR MAC (4-15, 4-30), and NR PHY (4-20, 4-25) layer devices (hereinafter referred to as layer, mixed with layer device) ) can be achieved. Of course, the wireless protocol of the next-generation mobile communication system may include more or fewer layers than the configuration shown in FIG. 4.

According to an embodiment of the present disclosure, the main functions of the NR SDAP layer devices 4-01 and 4-45 may include some of the following functions. However, it is not limited to the examples below:- Transfer of user plane data

- Mapping function of QoS flow and data bearer for uplink and downlink (mapping between a QoS flow and a DRB for both DL and UL)

- Marking QoS flow ID in both DL and UL packets for uplink and downlink

- A function to map the relective QoS flow to the data bearer for uplink SDAP PDUs (reflective QoS flow to DRB mapping for the UL SDAP PDUs).

According to an embodiment of the present disclosure, for SDAP layer devices (4-01, 4-45), the terminal transmits SDAP information to each PDCP layer device, each bearer, or each logical channel using a Radio Resource Control (RRC) message. You can set whether to use the header of the layer device (4-01, 4-45) or whether to use the function of the SDAP layer device (4-01, 4-45). In addition, when the SDAP layer device (4-01, 4-45) has the SDAP header set, the terminal sets a 1-bit indicator (NAS) reflecting the non-access stratum (NAS) QoS (Quality of Service) of the SDAP header. reflective QoS) and access layer (Access Stratum, AS) QoS reflection setting. With a 1-bit indicator (AS reflective QoS), the terminal updates or resets the mapping information for uplink and downlink QoS flows and data bearers. You can instruct them to do it. According to one embodiment, the SDAP header may include QoS flow ID information indicating QoS. According to another embodiment, QoS information can be used as data processing priority, scheduling information, etc. to support smooth service.

According to an embodiment of the present disclosure, the main functions of the NR PDCP layer devices 4-05 and 4-40 may include some of the following functions. However, it is not limited to the examples below.

- Header compression and decompression (ROHC only)

- Transfer of user data

- In-sequence delivery of upper layer PDUs

- Out-of-sequence delivery of upper layer PDUs

- Order reordering function (PDCP PDU reordering for reception)

- Duplicate detection of lower layer SDUs

- Retransmission of PDCP SDUs

- Encryption and decryption function (Ciphering and deciphering)

- Timer-based SDU discard in uplink.

In the above description, the reordering function of the NR PDCP layer devices (4-05, 4-40) refers to the function of reordering PDCP PDUs received from the lower layer in order based on PDCP SN (sequence number). can do. The reordering function of the NR PDCP layer device (4-05, 4-40) is the function of transmitting data to the upper layer in the reordered order, the function of transmitting data immediately without considering the order, and the function of transmitting data to the upper layer by reordering the order. It may include at least one of a function to record PDCP PDUs, a function to report status of lost PDCP PDUs to the transmitter, and a function to request retransmission of lost PDCP PDUs.

According to an embodiment of the present disclosure, the main functions of the NR RLC layer devices 4-10 and 4-35 may include some of the following functions. However, it is not limited to the examples below.

- Data transfer function (Transfer of upper layer PDUs)

- In-sequence delivery of upper layer PDUs

- Out-of-sequence delivery of upper layer PDUs

- ARQ function (Error Correction through ARQ)

- Concatenation, segmentation and reassembly of RLC SDUs

- Re-segmentation of RLC data PDUs

- Reordering of RLC data PDUs

- Duplicate detection function

- Protocol error detection

- RLC SDU deletion function (RLC SDU discard)

- RLC re-establishment function

In the above description, the in-sequence delivery function of the NR RLC layer devices (4-10, 4-35) may refer to the function of delivering RLC SDUs received from the lower layer to the upper layer in order. . When one RLC SDU is originally received by being divided into multiple RLC SDUs, the in-sequence delivery function of the NR RLC layer devices (4-10, 4-35) performs the function of reassembling and delivering them. It can be included.

According to an embodiment of the present disclosure, the in-sequence delivery function of the NR RLC layer devices (4-10, 4-35) converts the received RLC PDUs into RLC sequence number (SN) or PDCP sequence number (SN). It may include a function to reorder based on number. In addition, the sequential delivery function of the NR RLC layer devices 4-10 and 4-35 includes a function of rearranging the order and recording lost RLC PDUs, a function of reporting the status of the lost RLC PDUs to the transmitting side, and It may include at least one of the functions of requesting retransmission of lost RLC PDUs.

According to an embodiment of the present disclosure, the in-sequence delivery function of the NR RLC layer devices (4-10, 4-35) is, when there is a lost RLC SDU, the RLC up to the lost RLC SDU It may include a function to deliver only SDUs in order to the upper layer.

According to an embodiment of the present disclosure, the in-sequence delivery function of the NR RLC layer devices (4-10, 4-35) starts the timer if a predetermined timer expires even if there is a lost RLC SDU. It may include a function to deliver all previously received RLC SDUs in order to the upper layer.

According to an embodiment of the present disclosure, the in-sequence delivery function of the NR RLC layer devices (4-10, 4-35) is such that even if there is a lost RLC SDU, if a predetermined timer has expired, the in-sequence delivery function of the NR RLC layer device (4-10, 4-35) It may include a function to deliver all RLC SDUs in order to the upper layer.

According to an embodiment of the present disclosure, the NR RLC layer devices (4-10, 4-35) process RLC PDUs in the order in which they are received, regardless of the order of the sequence number (out-of sequence delivery). It can be transmitted to the NR PDCP layer device (4-05, 4-40).

According to an embodiment of the present disclosure, when the NR RLC layer device (4-10, 4-35) receives a segment, it receives the segments stored in the buffer or to be received at a later time, and creates one complete After reconfiguring it into an RLC PDU, it can be delivered to the NR PDCP layer device (4-05, 4-40).

According to an embodiment of the present disclosure, the NR RLC layer (4-10, 4-35) may not include a concatenation function, and the function is performed in the NR MAC layer (4-15, 4-30) Alternatively, it can be replaced with the multiplexing function of the NR MAC layer (4-15, 4-30).

In the above-described content, the out-of-sequence delivery function of the NR RLC layer devices (4-10, 4-35) delivers RLC SDUs received from the lower layer directly to the upper layer regardless of order. It can mean a function. The out-of-sequence delivery function of the NR RLC layer device (4-10, 4-35) is to reassemble and reassemble one RLC SDU when it is received separately into several RLC SDUs. It may include a transmission function. The out-of-sequence delivery function of the NR RLC layer device (4-10, 4-35) stores the RLC SN or PDCP SN of the received RLC PDUs and sorts the order to remove the lost RLC PDUs. It may include a recording function.

According to an embodiment of the present disclosure, the NR MAC layer devices (4-15, 4-30) can be connected to several NR RLC layer devices configured in one terminal, and the NR MAC layer devices (4-15, 4-30) )'s main functions may include some of the following functions: However, it is not limited to the examples below.

- Mapping function (Mapping between logical channels and transport channels)

- Multiplexing and demultiplexing function (Multiplexing/demultiplexing of MAC SDUs)

- Scheduling information reporting

- HARQ function (Error correction through HARQ)

- Priority handling between logical channels of one UE

- Priority handling between UEs by means of dynamic scheduling

- MBMS service identification function

- Transport format selection function

- Padding function

According to an embodiment of the present disclosure, the NR PHY layer devices (4-20, 4-25) channel code and modulate upper layer data, create OFDM symbols, and transmit them over a wireless channel, or OFDM signals received through a wireless channel. The operation of demodulating the symbol, decoding the channel, and transmitting it to the upper layer can be performed.

Figure 5 is a block diagram showing the structure of a terminal according to an embodiment of the present disclosure.

Referring to FIG. 5, the terminal may include an RF (Radio Frequency) processing unit 5-10, a baseband processing unit 5-20, a storage unit 5-30, and a control unit 5-40. there is. Of course, it is not limited to the above example, and the terminal may include fewer or more components than those shown in FIG. 5.

According to an embodiment of the present disclosure, the RF processing unit 5-10 may perform functions for transmitting and receiving signals through a wireless channel, such as band conversion and amplification of signals. The RF processing unit 5-10 upconverts the baseband signal provided from the baseband processing unit 5-20 into an RF band signal and transmits it through an antenna, and converts the RF band signal received through the antenna into a baseband signal. Can be down-converted. For example, the RF processing unit 5-10 may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a digital to analog convertor (DAC), an analog to digital convertor (ADC), etc. there is. Of course, it is not limited to the above example. In FIG. 5, only one antenna is shown, but the terminal may be equipped with multiple antennas. Additionally, the RF processing unit 5-10 may include a plurality of RF chains. Furthermore, the RF processing unit 5-10 may perform beamforming. For beamforming, the RF processing unit 5-10 may adjust the phase and size of each signal transmitted and received through a plurality of antennas or antenna elements. Additionally, the RF processing unit 5-10 can perform MIMO (Multi Input Multi Output) and can receive multiple layers when performing a MIMO operation. The RF processing unit 5-10 may perform reception beam sweeping by appropriately setting a plurality of antennas or antenna elements under the control of the control unit, or may adjust the direction and beam width of the reception beam so that the reception beam coordinates with the transmission beam. .

According to an embodiment of the present disclosure, the baseband processing unit 5-20 may perform a conversion function between a baseband signal and a bit string according to the physical layer standard of the system. For example, when transmitting data, the baseband processing unit 5-20 may generate complex symbols by encoding and modulating the transmission bit stream. Additionally, when receiving data, the baseband processing unit 5-20 may restore the received bit stream by demodulating and decoding the baseband signal provided from the RF processing unit 5-10. For example, when following the OFDM (orthogonal frequency division multiplexing) method, when transmitting data, the baseband processing unit 5-20 generates complex symbols by encoding and modulating the transmission bit string, and maps the complex symbols to subcarriers. After that, OFDM symbols can be configured through IFFT (inverse fast Fourier transform) operation and CP (cyclic prefix) insertion. In addition, when receiving data, the baseband processing unit 5-20 divides the baseband signal provided from the RF processing unit 5-10 into OFDM symbols and converts the signals mapped to subcarriers through FFT (fast Fourier transform). After restoring the received bit string, the received bit string can be restored through demodulation and decoding.

According to an embodiment of the present disclosure, the baseband processing unit 5-20 and the RF processing unit 5-10 transmit and receive signals as described above. Accordingly, the baseband processing unit 5-20 and the RF processing unit 5-10 may be referred to as a transmitting unit, a receiving unit, a transceiving unit, or a communication unit. Furthermore, at least one of the baseband processing unit 5-20 and the RF processing unit 5-10 may include a plurality of communication modules to support a plurality of different wireless access technologies. Additionally, at least one of the baseband processing unit 5-20 and the RF processing unit 5-10 may include different communication modules to process signals in different frequency bands. For example, different wireless access technologies may include wireless LAN (eg, IEEE 802.11), cellular network (eg, LTE), etc. Additionally, different frequency bands may include a super high frequency (SHF) (e.g., 2.NRHz, NRhz) band and a millimeter wave (mm wave) (e.g., 60GHz) band. The terminal can transmit and receive signals with the base station using the baseband processing unit 5-20 and the RF processing unit 5-10, and the signals may include control information and data.

According to an embodiment of the present disclosure, the storage unit 5-30 may store data such as basic programs, application programs, and setting information for operation of the terminal. In particular, the storage unit 5-30 may store information related to a second access node that performs wireless communication using a second wireless access technology. Additionally, the storage unit 5-30 may provide stored data upon request from the control unit 5-40. Additionally, the storage unit 5-30 may be composed of a plurality of memories. According to another embodiment, the storage unit 5-30 may store a program for performing a method of allocating an IP address in the IAB system described in this disclosure.

According to an embodiment of the present disclosure, the control unit 5-40 controls overall operations of the terminal. For example, the control unit 5-40 may transmit and receive signals through the baseband processing unit 5-20 and the RF processing unit 5-10. Additionally, the control unit 5-40 can write and read data to and from the storage unit 5-40. For this purpose, the control unit 5-40 may include at least one processor. For example, the control unit 5-40 may include a communication processor (CP) that performs control for communication and an application processor (AP) that controls upper layers such as application programs.

Figure 6 is a block diagram showing the structure of an NR base station according to an embodiment of the present disclosure. According to an embodiment of the present disclosure, the network entity (or network function), the IAB node, may have the same or similar configuration as the NR base station in FIG. 6.

Referring to FIG. 6, the base station may include an RF processing unit 6-10, a baseband processing unit 6-20, a backhaul communication unit 6-30, a storage unit 6-40, and a control unit 6-50. You can. Of course, it is not limited to the above example, and the base station may include fewer or more configurations than the configuration shown in FIG. 6.

According to an embodiment of the present disclosure, the RF processing unit 6-10 may perform functions for transmitting and receiving signals through a wireless channel, such as band conversion and amplification of signals. The RF processing unit 6-10 upconverts the baseband signal provided from the baseband processing unit 6-20 into an RF band signal and transmits it through an antenna, and converts the RF band signal received through the antenna into a baseband signal. Can be down-converted. For example, the RF processing unit 6-10 may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, etc. In FIG. 6, only one antenna is shown, but the first access node may be equipped with a plurality of antennas. Additionally, the RF processing unit 6-10 may include a plurality of RF chains. Furthermore, the RF processing unit 6-10 can perform beamforming. For beamforming, the RF processing unit 6-10 can adjust the phase and size of each signal transmitted and received through a plurality of antennas or antenna elements. The RF processing unit 6-10 can perform downlink MIMO operation by transmitting one or more layers.

According to an embodiment of the present disclosure, the baseband processing unit 6-20 may perform a conversion function between a baseband signal and a bit string according to the physical layer standard of the first wireless access technology. For example, when transmitting data, the baseband processing unit 6-20 may generate complex symbols by encoding and modulating the transmission bit stream. Additionally, when receiving data, the baseband processing unit 6-20 can restore the received bit stream by demodulating and decoding the baseband signal provided from the RF processing unit 6-10. For example, when following the OFDM method, when transmitting data, the baseband processing unit 6-20 generates complex symbols by encoding and modulating the transmission bit stream, maps the complex symbols to subcarriers, and performs IFFT. OFDM symbols can be configured through operations and CP insertion. In addition, when receiving data, the baseband processing unit 6-20 divides the baseband signal provided from the RF processing unit 6-10 into OFDM symbols, restores signals mapped to subcarriers through FFT operation, and then , the received bit string can be restored through demodulation and decoding. The baseband processing unit 6-20 and the RF processing unit 6-10 can transmit and receive signals as described above. Accordingly, the baseband processing unit 6-20 and the RF processing unit 6-10 may be referred to as a transmitting unit, a receiving unit, a transceiving unit, a communication unit, or a wireless communication unit.

According to an embodiment of the present disclosure, the backhaul communication unit 6-30 may provide an interface for communicating with other nodes in the network. The backhaul communication unit 6-30 can convert a bit string transmitted from the main base station to another node, for example, an auxiliary base station, a core network, etc., into a physical signal, and convert a physical signal received from another node into a bit string. there is.

According to an embodiment of the present disclosure, the storage unit 6-40 may store data such as basic programs, application programs, and setting information for operation of the main base station. In particular, the storage unit 6-40 can store information about bearers assigned to the connected terminal, measurement results reported from the connected terminal, etc. Additionally, the storage unit 6-40 may store information that serves as a criterion for determining whether to provide or suspend multiple connections to the terminal. Additionally, the storage unit 6-40 may provide stored data upon request from the control unit 6-50. The storage unit 6-40 may be composed of a storage medium such as ROM, RAM, hard disk, CD-ROM, and DVD, or a combination of storage media. Additionally, the storage unit 6-40 may be composed of a plurality of memories. According to some embodiments, the storage unit 6-40 may store a program for performing the method of allocating an IP address in the IAB system described in this disclosure.

According to an embodiment of the present disclosure, the control unit 6-50 can control the overall operations of the base station. For example, the control unit 6-50 may transmit and receive signals through the baseband processing unit 6-20 and the RF processing unit 6-10 or through the backhaul communication unit 6-30. Additionally, the control unit 6-50 can write and read data into the storage unit 6-40. For this purpose, the control unit 6-50 may include at least one processor. Additionally, each component of the base station can operate to perform embodiments of the present disclosure.

FIG. 7 is a diagram illustrating cell creation and cell connection operations of a terminal according to movement of a Mobile IAB node according to an embodiment of the present disclosure.

Referring to FIG. 7, the Mobile IAB node can connect to donor 1 as a source donor. Parent node or donor DU 1 can be controlled by donor 1. The Mobile IAB node operates cell 1 through the DU (Distributed Unit) of the Mobile IAB node, and terminals (UEs 1 to 3) can exchange data with the network through cell 1. In this situation, when the Mobile IAB node moves and approaches the area of the cell operated by donor DU 2 under the control of donor 2, the Mobile IAB node can receive a handover command from donor 1. According to this handover command, the Mobile IAB node moves the control plane of the Mobile IAB node's MT (Mobile Termination), the user plane, and the F1 context of the DU of the Mobile IAB node to the new donor 2, and then transfers the new Cell 2 can be started through cell operation instructions. After cell 2 operates, terminals (UEs 1 to 3) can perform handover from cell 1 to cell 2. After a certain time, or when the handover of all terminals to cell 2 is completed, donor 2 can issue a command to mobile IAB node to terminate operation of cell 1. Alternatively, cell 1 can be maintained for that time by providing specific time information to the handover command of the Mobile IAB node.

FIG. 8 is a flowchart illustrating an operation in which a mobile IAB node stores a handover command of a terminal and then transmits the handover command to the terminal after a new cell is operated, according to an embodiment of the present disclosure.

Referring to FIG. 8, in step 8-1, the Mobile IAB node can inform the donor node that it is a mobile IAB node in connected mode, and the donor node can recognize this.

In step 8-3, the donor node that recognizes that it is a Mobile IAB node can instruct the co-located DU of the Mobile IAB node to operate a cell through a logical DU. This instruction may include PCI (Physical Cell Identification) and/or NCGI (NR Cell Global Identifier) information associated with the current donor, the source donor. PCI and/or NCGI information may be conveyed as messages on the F1 interface. Additionally, an indicator as to whether to use hard split physical resources or shared physical resources when operating the cell may also be included.

In step 8-5, the Mobile IAB node can start operating a cell that broadcasts the source donor's PCI/NCGI by reflecting the corresponding logical DU operation information. At this time, in step 8-3, you can receive an instruction to use hard split physical resources, or if there is no instruction, you can operate the cell using hard split physical resources.

In step 8-7, it can be assumed that after the corresponding cell (Cell 1 in the figure) is started, the UEs (UE 1 to 3) have been handed over or made the first connection.

In steps 8-9, the measurement report set for the Mobile IAB node at a specific point in time may be triggered and reported to the source donor.

In steps 8-11, the source donor may decide to handover to the target donor based on the measurement report results. The source donor can send a HandoverRequest message (hereinafter referred to as HOReq message) to the target donor. The HOReq message may include an indicator of the Mobile IAB node and/or an indicator indicating full migration. In addition, the HOReq message includes context information of the migration IAB node, RRC configuration information of the currently operating MT, DU configuration information, the number of DRB/ERAB/BH RLC CHs in operation, and id information of each BH RLC CH and/or Information on the number of DRB/ERAB/BH RLC CHs desired to be operated by the target donor may be included. According to an embodiment of the present disclosure, the HOReq message includes UE context of terminals connected to a migrating IAB node, information such as currently operating RRC configuration information, DRB/ERAB information, and the number of DRB/ERABs desired to be operated in the target. may be included. In the case of an access UE, an indicator indicating that it is an access UE of a mobile IAB node may be included. Additionally, the DU information may include parameter information of the currently operating cell, including PCI and/or NCGI, and whether hard split resources or shared resources are used.

In step 8-13, when the target node receives the HOReq message in step 8-11, it performs admission control and selects the target cell to be used by the admitted iab node, that is, the parent node under the control of the target donor node or operated by the donor DU. You can create setting information to be used in cells. Additionally, the admitted access UE can create configuration information to be used in the target cell (later named cell 2) operating in the target donor.

In steps 8-15, the target donor may deliver a handoverRequestACK message to the source donor. This message includes configuration information in the target cell of the admitted IAB node created in steps 8-13 and/or configuration information in the target cell (cell 2) of the admitted access UE, and an indicator called access UE for each access UE, and/ Alternatively, for an admitted IAB node, the corresponding entity may include an indicator called IAB node.

In step 8-17, the source node may deliver configuration information for the access UE received in step 8-15, that is, RRCReconfiguration messages, to the mobile IAB node. At this time, the F1-AP message can be used. And this message may include a delayed RRCReconfiguration indicator for each terminal. When the Mobile IAB node receives a message containing the delayed RRCReconfiguration indicator, the corresponding RRCReconfiguration message can be stored in the mobile IAB node for each terminal until a specific condition is satisfied. And the stored RRCReconfiguration can be delivered to the terminal.

In step 8-19, the source node can transmit the configuration information (handover command) to be used in the target cell for the mobile IAB node, that is, the migrating IAB node, received in step 8-15 to the mobile IAB node as an F1-AP message. . The mobile IAB node that receives the message can perform handover.

However, steps 8-17 and steps 8-19 may not have a set order.

In step 8-21, the Mobile IAB node performs handover, applies the configuration information of the received handover command, performs random access to the target cell as necessary, and, if successful, transmits the RRCReconfigurationComplete message to the target cell. You can.

In step 8-23, the target donor node, which recognizes that the mobile IAB node has successfully connected to the target donor through the target cell, can notify the source of the mobile IAB node's successful connection to the target donor. Additionally, you can request the context information of the DU of the mobile IAB node and relocate it to yourself. And/or you can request additional F1, and when you want to establish a new DU and F1 interface of the mobile IAB node, you can update the mobile IAB node and F1 interface settings based on the relevant F1 configuration information.

In step 8-25, the target donor may request configuration update of the co-located DU of the mobile IAB node based on the DU configuration information received in step 8-23. At this time, a request can be made with an F1-AP message, and the F1-AP message can include an indicator to start a new cell to which the target donor-related factors are applied in the logical DU. As a target donor-related factor, PCI and/or NCGI information may be included, and in addition, an indicator regarding whether to use hard split physical resources or shared physical resources may be included when operating a new cell.

In steps 8-27, the Mobile IAB node can start/operate a new cell (cell 2) by applying the received cell information. At this time, PCI/NCGI information received from the target node can be broadcast. And the cell can be operated according to the physical resource operation method given in step 8-25. At this time, cell 1, which was used in the existing source donor, may be in operation as is.

In steps 8-29, if the DU succeeds in keying a new cell, the target donor can deliver a DU update complete message to the target node.

In step 8-31, when the new cell starts operating, the DU of the mobile IAB node can transmit the delayed RRCReconfiguration for each access UE received in step 8-17 to each terminal. At this time, since the terminals are connected to cell 1, the RRCReconfiguration message is delivered through cell 1. At this time, the mobile IAB node can distribute the timing of delivering RRCReconfiguration to each terminal. RRCReconfiguration may be sequentially delivered to the terminal at certain set time intervals, or RRCReconfiguration may be sequentially delivered to the terminal at intervals of random values within a specific range. The specific range value information can be transmitted from the target donor to the source donor in steps 8-15, and the source donor can transmit it to the mobile IAB node in steps 8-17.

In step 8-33, when each terminal receives the delayed RRCReconfiguration through cell 1, the received RRCReconfiguration configuration is applied and the RRCReconfigurationComplete message is delivered to the lower layer. And, if necessary, random access can be performed to the target cell included in the RRCReconfiguration message.

In step 8-35, the target cell is cell 2, and if the terminal succeeds in random access, it can transmit the complete message in the lower layer.

In step 8-37, the DU of the Mobile IAB node receives a complete message from cell 2 and can recognize that the handover of the corresponding access UE was successful.

In step 8-39, the Mobile IAB node can store the complete message received in step 8-37 in ULRRCmsgTransfer, an F1-AP message, and deliver it to the target donor. The target donor's CU can confirm that the corresponding access UE sends a complete message through cell 2.

In step 8-41, if all access UEs send a complete message through the new cell (cell 2), all access UEs can be considered connected to the target donor node.

In step 8-43, when the target donor node recognizes that the access UE that issued all HO commands transmits a complete message through a new cell through the received RRCReconfigurationComplete message, it sends the cell used by the source donor to the mobile IAB node. Instructions may be given to terminate or suspend operation. This instruction can be delivered including the corresponding indicator using the F1-AP message.

In step 8-45, the mobile IAB node that received the message transmitted in step 8-43 can tell the DU of the mobile IAB node to turn off the cell (cell 1) used by the source node.

In step 8-47, when turning off the DU's cell is completed, the DU of the IAB node can transmit the success of turning off cell 1 to the target donor through the DU configuration update complete message. The corresponding directive may be included in the message.

According to an embodiment of the present disclosure, if the PCI value of the cell to be used in the target donor step is the same as the PCI value of the cell used in the source donor step, the operation of operating a separate new cell can be omitted. In this case, rather than an HO command, an RRCReconfiguration that does not include the reconfigurationWithSync field can be created from the target node and delivered to the access UE. In this case, the RRCReconfiguration of the access UE target created in steps 8-13 is delivered to the source donor through steps 8-15, and is delivered to the mobile IAB node through step 9. At this time, the F1AP message including RRCReconfiguration in steps 8-17 may not have a delayed RRCReconfiguration indicator. The mobile IAB node that received this message can deliver the received general RRCReconfiguration message to the terminal without delay according to its own scheduling.

According to another embodiment of the present disclosure, in the case of normal or delayed RRCReconfiguration received in step 8-17, RACH less HO (Handover) may be indicated. That is, the RRCReconfiguration message may include target cell information and the time/frequency location of the UL grant resource in the corresponding cell in advance, and may include timing advance information to be newly applied when necessary. The access UE that receives this information can apply only RRCReconfiguration without RACH operation and transmit a complete message through the target cell's given UL grant and through UL transmission considering the given TA.

FIG. 9 is a flowchart illustrating an operation in which handover of a UE is performed when the target donor can store the HO command message of the access UE according to an embodiment of the present disclosure.

Description of the same steps as in the case of FIG. 8 will be omitted.

Referring to FIG. 9, in steps 9-13, the target donor may store the configuration information of the target cell for the access UE in the target donor node until a certain point in time without transmitting it to the source node and mobile IAB node.

In steps 9-15, the target donor may also deliver the HOReqAck message to the source donor node, including only the RRC configuration information in the target cell of the mobile IAB node.

In steps 9-17, the source node may transmit an HO command for the mobile IAB node to the mobile IAB node.

In steps 9-19, the mobile IAB node may apply the received handover command, perform random access considering the parent node operating in the target donor node or the cell operating in the donor DU as the target cell, and transmit the RRCReconfigurationComplete message. .

In steps 9-29, the target donor node can recognize that a new cell is turned on and deliver a handover command (RRCReconfiguration) targeting the new cell to access UEs. At this time, the F1-AP message DLRRCmsgTransfer message can be used, and this message includes the RRCReconfiguration message, and also an indicator instructing to transfer the RRCReconfig message through cell 1, that is, the cell used by the source donor, or a Boolean of the donor/target cell. May include indicators.

In step 9-31, when the mobile IAB node receives the message in step 13-2, it can transmit the received RRCReconfiguration to the corresponding access UE through the cell used in the source, that is, cell 1.

FIG. 10 is a flow for explaining an operation in which handover of a UE is performed when conditional handover is applied to an access UE according to an embodiment of the present disclosure.

Description of the same steps as in FIG. 8 will be omitted.

Referring to FIG. 10, in steps 10-11, the source donor may determine handover to the target donor based on the measurement report result. Accordingly, the source donor can send a HandoverRequest message (hereinafter referred to as HOReq) to the target donor. The HOReq message may include an indicator of the mobile IAB node and/or an indicator indicating full migration. In addition, as context information of the migration IAB node, RRC configuration information of the currently operating MT, DU configuration information, and the number of DRB/ERAB/BH RLC CHs in operation and id information of each BH RLC CH and/or from the target donor Information on the number of DRB/ERAB/BH RLC CHs desired to be operated may be included. Additionally, as the UE context of terminals connected to the migrating IAB node, information such as currently operating RRC configuration information, DRB/ERAB information, and the number of DRB/ERAB desired to be operated in the target may be included. According to an embodiment according to the present disclosure, in the case of an access UE, an indicator indicating that it is an access UE of a mobile IAB node may be included. Additionally, the DU information may include parameter information of the currently operating cell, including whether PCI and/or NCGI, hard split resources, or shared resources are used. Additionally, the source node may include an indicator requesting conditional configuration for the access UE.

In step 10-13, when the target node receives the HOReq message of step 10-11, it performs admission control and selects the target cell to be used by the admitted iab node, that is, the parent node under the control of the target donor node or operated by the donor DU. You can create setting information to be used in cells. Additionally, the admitted access UE can create configuration information to be used in the target cell (later named cell 2) operating in the target donor. Additionally, if the conditional configuration indicator is included, the configuration information of access UEs included in the HOReq message can be recognized as a conditional handover message and made into the corresponding conditional handover message.

In steps 10-17, the source node transmits a general RRCReconfiguration message to the mobile IAB node for each access UE instead of Delayed RRCReconfiguration. This message from F1AP is used. The mobile IAB node that received the RRCReconfiguration message delivers a conditional handover message to each access UE according to its schedule without delay. This can be passed through cell 1.

Steps 10-19 are the same as steps 8-19 in FIG. 8. However, steps 10-19 may have to be performed before steps 10-17.

In steps 10-29, after the new cell is turned on, the CHO conditions of each access UE may be satisfied.

According to another embodiment according to the present disclosure, the conditional handover command message may include time information for each access UE to perform HO after a specific time after the condition is satisfied. This information can be included by the target node in the conditional handover command in steps 10-13. This information may be information at a certain fixed time, or it may be a random variable within a certain range. The information included in the conditional handover command message may be intended to change the time of HO performance to prevent all access UEs from performing HO at the same time after cell 2 is turned on. The designated time information may be SFN, radio frame, system frame, or slot unit time, absolute time units such as mili sec/micro sec/nano sec, or symbol level time units. Or it may be a combination of the above units. However, it is not limited to this.

In another embodiment, when operating the conditional handover, the handover of the terminal of the conditional handover is collectively performed through an indicator through system information or common DCI of the PDCCH, rather than a handover based on a previously given measurement event. You can order an over. In this case, the conditional handover configuration information or the RRCReconfiguration message delivering the corresponding configuration information may include an indicator that the conditional handover condition is through system information or common DCI of the PDCCH. Additionally, the conditional handover configuration information or the RRCReconfiguration message transmitted including the corresponding configuration information may include a time value that ensures that each handover is performed after a specific delay time after the execution instruction. In this case, after receiving the conditional handover instruction, the terminal can perform conditional handover after a given delay time. Alternatively, after receiving a conditional handover instruction, conditional handover can be performed, but random access and complete message transmission can be performed after a delayed time. The specified time information may be SFN, radio frame, system frame, or slot unit time, absolute time units such as milli sec / micro sec / nano sec, or symbol level time units. Or it may be a combination of the above units.

In addition, the program can be accessed through a communication network such as the Internet, Intranet, LAN (Local Area Network), WLAN (Wide LAN), or SAN (Storage Area Network), or a combination of these. It may be stored in an attachable storage device that can be accessed. This storage device can be connected to a device performing an embodiment of the present disclosure through an external port. Additionally, a separate storage device on a communication network may be connected to the device performing an embodiment of the present disclosure.

In the specific embodiments of the present disclosure described above, elements included in the disclosure are expressed in singular or plural numbers depending on the specific embodiment presented. However, singular or plural expressions are selected to suit the presented situation for convenience of explanation, and the present disclosure is not limited to singular or plural components, and even components expressed in plural may be composed of singular or singular. Even expressed components may be composed of plural elements.

Meanwhile, in the detailed description of the present disclosure, specific embodiments have been described, but of course, various modifications are possible without departing from the scope of the present disclosure. Therefore, the scope of the present disclosure should not be limited to the described embodiments, but should be determined not only by the scope of the patent claims described later, but also by the scope of this patent claim and equivalents.

Claims (1)

In a method performed by an integrated access and backhaul (IAB) node in a wireless communication system, the method includes:
Receiving a message including an RRCReconfiguration message from a source node and configuration information to be used in a target cell operated by a target node;
Based on the received configuration information, transmitting the RRCReconfiguration message to a target cell;
If the random access procedure of the terminal to the target cell is successful, receiving an RRCReconfigurationComplete message from the target cell; and
A method comprising transmitting a message requesting termination of operation of a cell operated by the source node based on the received RRCReconfigurationComplete message.

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