Apparatus and method of operation for network control repeater related to beam failure detection in next generation mobile communications

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. A method performed by an NCR mobile terminal (MT) in a wireless communication system includes receiving side control information including a forwarding configuration. The method includes sending a first indication of stopping forwarding to NCR forwarding in the event of a beam failure. The method includes initiating a beam failure recovery procedure for the NCR MT. The method includes sending a second indication to the NCR forwarding to resume the forwarding by using the forwarding configuration in the event that the beam failure recovery process is successfully completed.

Description

TECHNICAL FIELD

[0001] The disclosure relates generally to operation of a user equipment (UE) in a mobile communication system, and more particularly, to a wireless repeater controlled by a base station (BS). BACKGROUND

[0002] Fifth generation (5G) mobile communication technologies define broad frequency bands for um fast data rate and new services of high reliability and low latency, and can be implemented using ultra-high frequency bands (mmWave) in addition to the frequency bands (sub-6GHz) used by existing mobile communications technologies.

[0003] In sixth generation (6G) mobile communication technologies, which can be referred to as beyond 5G systems, in order to achieve a data rate 50 times faster than that of 5G mobile communication technologies and a latency 1 / 10 of that of 5G mobile communication technologies, there have been ongoing discussions on implementing 6G mobile communication technologies in terahertz (THz) bands (e.g., 95GHz to 3THz bands).

[0004] Since the initial development of 5G mobile communication technologies, in order to support services related to enhanced mobile broadband (eMBB), ultra-reliable low-latency communication (URLLC), and massive machine-type communication (mMTC) and meet performance requirements therefor, there have been ongoing standardization discussions on the following: beamforming and massive multiple input multiple output (MIMO) for reducing path loss of radio waves and increasing the transmission distance of radio waves in mmWave; support for numerology (e.g., operating multiple subcarrier spacings) for efficient utilization of mmWave resources and time slots; initial access techniques for supporting multi-beam transmission and wideband; definition and operation of bandwidth parts (BWPs); new channel coding methods such as low-density parity-check (LDPC) codes for large data transmission and polar codes for high-reliability transmission of control information; layer 2 (L2) pre-processing; and network slicing for providing a dedicated network dedicated to a specific service.

[0005] In view of services supported by the new 5G mobile communication technologies, there are ongoing discussions on improvements and performance enhancements of initial 5G mobile communication technologies, for example, on physical layer standardization of technologies such as vehicle-to-everything (V2X) for assisting driving decisions of autonomous vehicles based on information on positions and statuses of vehicles transmitted by the vehicles and for enhancing user convenience; new radio unlicensed (NR-U) aimed at making system operations comply with various regulatory requirements in unlicensed bands; NR UE power saving; non-terrestrial networks (NTNs), which are direct communications between UEs and satellites for providing coverage in areas where communication with terrestrial networks is unavailable; and positioning.

[0006] In the air interface architecture / protocol, there is ongoing standardization on technologies such as Industrial Internet of Things (IIoT) for supporting new services via interworking and convergence with other industries, Integrated Access and Backhaul (IAB) for providing a node for network service area expansion by supporting a wireless backhaul link and an access link in an integrated manner, mobility enhancement including conditional handover and Dual Active Protocol Stack (DAPS) handover, and two-step random access (two-step random access channel (RACH) of NR) for simplifying random access procedures.

[0007] In the system architecture / service aspect, there is ongoing standardization on technologies such as a 5G baseline architecture (e.g., service-based architecture or service-based interface), for convergence with Network Function Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and Mobile Edge Computing (MEC) for receiving services based on UE location.

[0008] With the commercialization of 5G mobile communication systems, it is expected that the number of devices connected to the communication network will increase exponentially, and accordingly, enhanced functionality and performance of the 5G mobile communication system and integrated operation of connected devices will be necessary. To this end, new research is scheduled related to technologies such as extended reality (XR) for efficiently supporting augmented reality (AR), virtual reality (VR), mixed reality (MR), etc., 5G performance improvement and complexity reduction by utilizing artificial intelligence (AI) and machine learning (ML), AI service support, metaverse service support, drone communication, etc.

[0009] The development of 5G mobile communication systems will also serve as a basis for developing technologies for providing coverage of THz bands for 6G mobile communication technology using new waveforms, multi-antenna transmission technologies such as Full Dimensional MIMO (FD-MIMO), array antennas, and large-scale antennas, metamaterial-based lenses and antennas for improving THz band signal coverage, high-dimensional spatial multiplexing technology using Orbital Angular Momentum (OAM), and Reconfigurable Intelligent Surface (RIS), and full-duplex technology for increasing frequency efficiency and improving system networks of 6G mobile communication technology, AI-based communication technology for implementing system optimization by utilizing satellites and AI from the design stage and internalizing end-to-end AI support functions, and next-generation distributed computing technology for implementing services by utilizing super-high-performance communication and computing resources to a complex degree exceeding the limitations of UE operating capabilities.

[0010] As the above-described development of mobile communication systems can provide various services, there is a need for a method of efficiently providing services. SUMMARY

[0011] TECHNICAL SOLUTION

[0012] Accordingly, an aspect of the disclosure is to provide a method for a network-controlled relay (NCR) to suspend operation of a forwarding entity upon occurrence of a beam failure (BF) and to perform upon recovery from the BF.

[0013] According to an aspect of the disclosure, a method performed by an NCR mobile terminal (MT) in a wireless communication system includes receiving sidelink control information including a forwarding configuration. The method includes transmitting, to an NCR forwarding, a first indication to stop forwarding in case of occurrence of a beam failure. The method includes initiating a beam failure recovery procedure for the NCR MT. The method includes transmitting, to the NCR forwarding, a second indication to resume forwarding by using the forwarding configuration in case of successful completion of the beam failure recovery procedure.

[0014] According to an aspect of the disclosure, an NCR MT includes a transceiver and at least one processor. The at least one processor is configured to receive sidelink control information including a forwarding configuration. The at least one processor is configured to transmit, to an NCR forwarding, a first indication to stop forwarding in case of occurrence of a beam failure. The at least one processor is configured to initiate a beam failure recovery procedure for the NCR MT. The at least one processor is configured to transmit, to the NCR forwarding, a second indication to resume forwarding by using the forwarding configuration in case of successful completion of the beam failure recovery procedure.

[0015] According to an aspect of the disclosure, a method performed by an NCR forwarding in a wireless communication system includes receiving, from an NCR MT, a first indication to stop forwarding in case of occurrence of a beam failure. The method includes receiving, from the NCR MT, a second indication to resume forwarding by using a forwarding configuration in case of successful completion of a beam failure recovery procedure, wherein the forwarding configuration is received before the beam failure.

[0016] According to an aspect of the disclosure, an NCR forwarding includes a transceiver and at least one processor. The at least one processor is configured to receive, from an NCR MT, a first indication to stop forwarding in case of occurrence of a beam failure. The at least one processor is configured to receive, from the NCR MT, a second indication to resume forwarding by using a forwarding configuration in case of successful completion of a beam failure recovery procedure, wherein the forwarding configuration is received before the beam failure. BRIEF DESCRIPTION OF DRAWINGS

[0017] The above and other aspects, features, and advantages of certain embodiments of the disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which:

[0018] Figure 1 A long term evolution (LTE) system according to an embodiment is illustrated;

[0019] Figure 2 A radio protocol architecture of an LTE system according to an embodiment is illustrated;

[0020] Figure 3 A next-generation mobile communication system according to an embodiment is illustrated;

[0021] Figure 4 A radio protocol architecture of a next-generation mobile communication system according to an embodiment is illustrated;

[0022] Figure 5 A UE according to an embodiment is illustrated;

[0023] Figure 6 An NR BS according to an embodiment is illustrated;

[0024] Figure 7 An NCR according to an embodiment is illustrated;

[0025] Figure 8 A procedure for performing BF recovery according to an embodiment is illustrated;

[0026] Figure 9 is a signal flow diagram illustrating a method of recovering Forward (FWD) On according to an embodiment; and

[0027] Figure 10 is a signal flow diagram illustrating a method of recovering FWD On based on information from a network according to an embodiment. DETAILED DESCRIPTION

[0028] Hereinafter, the principle of operation of the present disclosure will be described in detail with reference to the accompanying drawings.

[0029] In the following description of the present disclosure, when it is considered that well-known functions or configurations can unnecessarily obscure the essence of the present disclosure, well-known functions or configurations are not described in detail. The terms used in the specification are defined in consideration of the functions used in the present disclosure, and can be changed according to the intention of the user or the operator or the usual method. Therefore, the definition of the terms is understood based on the entire description of the present specification.

[0030] In this document, in order to facilitate description, terms indicating an access node as used in the following description, terms indicating a network entity, terms indicating a message, terms indicating an interface between network entities, and terms indicating various identification information are exemplified. Therefore, the present disclosure is not limited to the terms used below, and other terms indicating objects having equivalent technical meanings can be used.

[0031] Throughout the disclosure, the expression "at least one of a, b, or c" indicates only a, only b, only c, both a and b, both a and c, both b and c, all of a, b, and c, or variations thereof.

[0032] Throughout the specification, a layer can also be referred to as an entity.

[0033] Herein, the BS is an entity that allocates resources to a terminal, and can be at least one of a next-generation Node B (gNB), an evolved Node B (eNB), a Node B, a radio access unit, a BS controller, or a node on a network.

[0034] The terminal can include a UE, a mobile station (MS), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing a communication function.

[0035] Herein, a downlink (DL) is a wireless transmission path of a signal transmitted from a BS to a UE, and an uplink (UL) is a wireless transmission path of a signal transmitted from a UE to a BS.

[0036] Although the following description can be provided by referring to an LTE or an LTE-Advanced (LTE-A) system as an example, embodiments of the disclosure are also applicable to other communication systems having a similar technical background or channel structure. For example, embodiments of the disclosure can be applicable to a system including 5G NR communication technology developed after the LTE-A system, and 5G can indicate a concept including LTE, LTE-A, and other similar services according to related technologies. The disclosure is also applicable to other communication systems with modifications made by those of ordinary skill in the art on their own discretion without departing from the scope of the disclosure.

[0037] Each block in the flowchart diagrams and combinations of blocks in the flowchart diagrams can be implemented by computer program instructions.

[0038] The computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate means for performing the functions specified in the flowchart block or blocks. The computer program instructions can also be stored in a computer- executable or computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer- executable or computer-readable memory produce an article of manufacture including instructions which implement the functions specified in the flowchart block or blocks. The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide operations for implementing the functions specified in the flowchart block or blocks.

[0039] Also, each block in the flowchart can represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical functions.

[0040] In some alternative implementations, the function(s) noted in the blocks can occur out of order. For example, two blocks that are shown in succession can in fact be executed substantially concurrently or the blocks can sometimes be executed in the reverse order, depending upon the functionality involved.

[0041] The term "unit" as used herein can refer to a software or hardware component such as a field programmable gate array (FPGA) or application specific integrated circuit (ASIC) that is configured to perform certain operations. The term "unit" is not limited to software or hardware and can include a combination of both, for example. A "unit" can be configured to operate on or within a programmable data processing apparatus, for example. Accordingly, as an example, "units" can include components of a software, an object, an executable, a thread of execution, a program, an application, a routine, a subroutine, a function, an attribute, a process, a procedure, a subroutine, a program code segment, a driver, firmware, microcode, a circuit, a database, a data structure, a table, a array, and a variable. The functionality provided for in the elements and "units" can be combined into fewer elements and "units" or further separated into additional elements and "units". In addition, elements and "units" can be implemented to operate with one or more central processing units (CPUs) in a device or a secure multimedia card. Further, a "unit" can include one or more processors.

[0042] For ease of description, the present disclosure uses terms and names defined in 5G system (5GS) and NR regulations, which are standards defined by the 3rd Generation Partnership Project (3GPP). However, the present disclosure is not limited to these terms and names, and can be equally applied to communication systems conforming to other standards.

[0043] Figure 1 An LTE system according to an embodiment is illustrated.

[0044] Referring to Figure 1 A radio access network of the LTE system includes a plurality of next-generation BSs (e.g., eNBs, Node Bs, or BSs) 1-05, 1-10, 1-15, and 1-20, a mobility management entity (MME) 1-25, and a serving gateway (S-GW) 1-30. A UE (or terminal) 1-35 can access an external network via the eNBs 1-05, 1-10, 1-15, or 1-20 and the S-GW 1-30.

[0045] The eNB 1-05, 1-10, 1-15, or 1-20 can correspond to a conventional Node B of a universal mobile telecommunications system (UMTS). The eNB 1-05, 1-10, 1-15, or 1-20 can be connected to the UE 1-35 via a wireless channel and can perform a complex function compared to the conventional Node B.

[0046] In the LTE system, all user traffic data including real-time services such as voice over Internet protocol (VoIP) can be serviced via a shared channel. Therefore, an entity for performing scheduling by checking state information of a UE, which includes buffer state information, available transmit power state information, and channel state information, can be required, and the eNB 1-05, 1-10, 1-15, or 1-20 can operate as such an entity.

[0047] The eNB can generally control a plurality of cells. For example, the LTE system can implement a data rate of 100 Mbps using a radio access technology such as orthogonal frequency division multiplexing (OFDM) at a bandwidth of 20 MHz. In addition, the LTE system can use adaptive modulation and coding (AMC) to determine a modulation scheme and a channel coding rate according to a channel state of the UE 1-35.

[0048] The S-GW 1-30 is an entity for providing a data bearer, and can establish or release the data bearer according to control of the MME 1-25. The MME 1-25 is an entity for performing a mobility management function and various control functions for the UE 1a-35, and can be connected to a plurality of eNBs 1-05, 1-10, 1-15, and 1-20.

[0049] Figure 2 A radio protocol architecture of the LTE system according to an embodiment is illustrated.

[0050] Referring to Figure 2The radio protocol architecture of the LTE system includes packet data convergence protocol (PDCP) layers 2-05 and 2-40, radio link control (RLC) layers 2-10 and 2-35, medium access control (MAC) layers 2-15 and 2-30, and physical (PHY) layers lb-20 and lb-25 for the UE and the LTE eNB, respectively.

[0051] The PDCP layer 2-05 or 2b-40 is responsible for, for example, Internet Protocol (IP) header compression / decompression. More specifically, the functions of the PDCP layer 2-05 or 2b-40 can be summarized as follows:

[0052] - Header compression and decompression: Robust Header Compression (ROHC) only

[0053] - Transfer of user data

[0054] - In-sequence delivery of upper layer packet data units (PDUs) at PDCP re-establishment procedure in RLC acknowledged mode (AM)

[0055] - PDCP PDU routing for transmission and PDCP PDU reordering for reception for split bearers (RLC AM only) in dual connectivity (DC)

[0056] - Duplicate detection of lower layer service data units (SDUs) at PDCP re-establishment procedure in RLC AM

[0057] - Retransmission of PDCP SDUs at handover for RLC AM and of PDCP PDUs at PDCP data recovery procedure for split bearers in DC

[0058] - Ciphering and deciphering

[0059] - Timer-based SDU discard in UL

[0060] The RLC layer 2-10 or 2-35 performs, for example, automatic repeat request (ARQ) operation by reconfiguring PDCP PDUs to appropriate sizes. More specifically, the functions of the RLC layer 2-10 or 2-35 can be summarized as follows:

[0061] - Transfer of upper layer PDUs

[0062] - Error correction through ARQ (only for AM data transfer)

[0063] - Concatenation, segmentation, and reassembly of RLC SDUs (only for unacknowledged mode (UM) and AM data transfer)

[0064] - Re-segmentation of RLC data PDUs (only for AM data transfer)

[0065] - Reordering of RLC data PDUs (only for UM and AM data transfer)

[0066] - Duplicate detection (only for UM and AM data transfer)

[0067] - Protocol error detection (only for AM data transfer)

[0068] - RLC SDU discard (only for UM and AM data transfer)

[0069] - RLC re-establishment

[0070] The MAC layer 2-15 or 2-30 can be connected to multiple RLC layers configured for one UE, and can multiplex and demultiplex RLC PDUs into and from MAC PDUs. More specifically, the functions of the MAC layer 2-15 or 2-30 can be summarized as follows:

[0071] - Mapping between logical channels and transport channels

[0072] - Multiplexing of MAC SDUs belonging to one or different logical channels into transport blocks (TBs) / demultiplexing of MAC SDUs belonging to one or different logical channels from TBs, where the TBs are delivered to / from the physical layer on the transport channel

[0073] - Scheduling information reporting

[0074] - Error correction through hybrid ARQ (HARQ)

[0075] - Prioritization between logical channels of one UE

[0076] - Prioritization between UEs by means of dynamic scheduling

[0077] - Multimedia broadcast / multicast service (MBMS) identification

[0078] - Transport format selection

[0079] - Padding

[0080] The PHY layer 2-20 or 2-25 can encode and modulate an upper layer data channel into an OFDM symbol and transmit the OFDM symbol via a wireless channel, or can demodulate an OFDM symbol received via a wireless channel and channel-decode and deliver the OFDM symbol to an upper layer.

[0081] Figure 3 A next-generation mobile communication system according to an embodiment is illustrated.

[0082] Reference Figure 3, a radio access network of a next-generation mobile communication system (e.g., NR or 5GS) can include a next-generation BS (i.e., NR Node B, e.g., NR gNB or NR BS) 3-10 and an NR core network (NR CN) 3-05. An NR UE (or NR terminal) 3-15 can access an external network via the NR gNB 3-10 and the NR CN 3-05.

[0083] The NR gNB 3-10 can correspond to an eNB of a legacy LTE system. The NR gNB 3-10 can be connected to the NR UE 3-15 via a wireless channel and can provide a more superior service compared to a legacy Node B.

[0084] In the NR or 5G system, all user traffic data can be serviced via a shared channel. Therefore, an entity for performing scheduling by collecting, for example, buffer status information of a UE, available transmission power status information, and channel status information can be required, and the NR gNB 3-10 can operate as such an entity.

[0085] The NR gNB 3-10 can control a plurality of cells.

[0086] In the NR or 5G system, a bandwidth greater than a legacy maximum bandwidth of a legacy LTE system can be applied to achieve an ultra-high data rate. In addition, a beamforming technique can be additionally associated with OFDM as a radio access technology. AMC can also be used to determine a modulation scheme and a channel coding rate according to a channel status of the NR UE 3-15.

[0087] The NR CN 3-05 can perform functions such as mobility support, bearer setup, quality of service (QoS) configuration, etc. The NR CN 3-05 is an entity for performing a mobility management function and various control functions on the NR UE 3-15, and can be connected to a plurality of BSs.

[0088] In addition, the NR or 5G system can cooperate with the LTE system, and the NR CN 3-05 can be connected to an MME 3-25 via a network interface. The MME 3-25 can be connected to an eNB 3-30 that is an LTE BS.

[0089] Figure 4 FIG. illustrates a radio protocol architecture of a next-generation mobile communication system according to an embodiment.

[0090] Reference Figure 4, the radio protocol architecture of the next generation mobile communication system can include NR service data adaptation protocol (SDAP) layers 4-01 and 4-45 for a UE and an NR gNB, respectively, NR PDCP layers 4-05 and 4-40, NR RLC layers 4-10 and 4-35, NR MAC layers 4-15 and 4-30, and NR PHY layers 4-20 and 4-25.

[0091] The functions of the NR SDAP layer 4-01 or 4-45 can include some of the following functions:

[0092] - transfer of user plane data

[0093] - mapping between QoS flows and data radio bearers (DRBs) for both DL and UL

[0094] - marking QoS flow identity (ID) in both DL and UL packets

[0095] - reflective QoS flow to DRB mapping for UL SDAP PDUs

[0096] With respect to the NR SDAP layer 4-01 or 4-45, the UE can be configured with information on whether to use a header of the NR SDAP layer 4-01 or 4-45 or use the functions of the NR SDAP layer 4-01 or 4-45 by using a radio resource control (RRC) message per PDCP layer 4-05 or 4-40, per bearer, or per logical channel. When the SDAP header is configured, a 1-bit non-access stratum (NAS) reflective QoS indicator and a 1-bit access stratum (AS) reflective QoS indicator of the SDAP header can be used to indicate that the UE update or reconfigure UL and DL QoS flow and data bearer mapping information. The SDAP header can include QoS flow ID information indicating QoS. The QoS information can be used as data processing priority information or scheduling information for properly supporting a service.

[0097] The functions of the NR PDCP layer 4-05 or 4-40 can include some of the following functions:

[0098] - header compression and decompression: ROHC only

[0099] - transfer of user data

[0100] - in-sequence delivery of upper layer PDUs

[0101] - out-of-sequence delivery of upper layer PDUs

[0102] - PDCP PDU reordering for reception

[0103] - duplicate detection of lower layer SDUs

[0104] - retransmission of PDCP SDUs

[0105] - ciphering and deciphering

[0106] - timer-based SDU discard in UL

[0107] In the above description, the reordering function of the NR PDCP layer 4-05 or 4-40 can indicate a function of reordering PDCP PDUs received from a lower layer on the basis of PDCP sequence numbers (SNs). The reordering function of the NR PDCP layer 4-05 or 4-40 can include a function of delivering reordered data to an upper layer in order, or can include a function of immediately delivering reordered data out of order, can include a function of recording missing PDCP PDUs by reordering received PDCP PDUs, can include a function of reporting state information of missing PDCP PDUs to a transmitter, and a function of requesting retransmission of missing PDCP PDUs.

[0108] The functions of the NR RLC layer 4-10 or 4-35 can include at least some of the following functions:

[0109] - transfer of upper layer PDUs

[0110] - in-sequence delivery of upper layer PDUs

[0111] - out-of-sequence delivery of upper layer PDUs

[0112] - error correction through ARQ

[0113] - concatenation, segmentation, and reassembly of RLC SDUs

[0114] - re-segmentation of RLC data PDUs

[0115] - reordering of RLC data PDUs

[0116] - duplicate detection

[0117] - protocol error detection

[0118] - RLC SDU discard

[0119] - RLC re-establishment

[0120] In the above description, the in-sequence delivery function of the NR RLC layer 4-10 or 4-35 can indicate a function of delivering RLC SDUs received from a lower layer to an upper layer in order. When multiple RLC SDUs segmented from one RLC SDU are received, the in-sequence delivery function of the NR RLC layer 4-10 or 4-35 can include a function of reassembling the RLC SDUs and delivering the reassembled RLC SDUs.

[0121] The in-sequence delivery function of the NR RLC layer 4-10 or 4-35 can include a function of reordering received RLC PDUs on an RLC SN or PDCP SN basis, can include a function of recording missing RLC PDUs by reordering the received RLC PDUs, can include a function of reporting status information of the missing RLC PDUs to the transmitter, and can include a function of requesting retransmission of the missing RLC PDUs.

[0122] The in-sequence delivery function of the NR RLC layer 4-10 or 4-35 can include a function of delivering only RLC SDUs before a missing RLC SDU in-sequence to an upper layer when the missing RLC SDU exists.

[0123] The in-sequence delivery function of the NR RLC layer 4-10 or 4-35 can include a function of delivering all RLC SDUs received before a timer starts in-sequence to an upper layer even when a missing RLC SDU exists when the certain timer expires.

[0124] The in-sequence delivery function of the NR RLC layer 4-10 or 4-35 can include a function of delivering all RLC SDUs received up to a current time in-sequence to an upper layer even when a missing RLC SDU exists when a certain timer expires.

[0125] The NR RLC layer 4-10 or 4-35 can process RLC PDUs in a reception order, and can deliver the RLC PDUs to the NR PDCP layer 4-05 or 4-40 regardless of SNs (out-of-sequence delivery).

[0126] When the NR RLC layer 4-10 or 4-35 receives a segment, the NR RLC layer 4-10 or 4-35 can reassemble the segment into an entire RLC PDU with other segments stored in a buffer or subsequently received, and can transfer the RLC PDU to the NR PDCP layer 4-05 or 4-40.

[0127] The NR RLC layer 4-10 or 4-35 can not have a concatenation function, and the NR MAC layer 4-15 or 4-30 can perform the concatenation function, or the concatenation function can be replaced with a multiplexing function of the NR MAC layer 4-15 or 4-30.

[0128] In the above description, the out-of-sequence delivery function of the NR RLC layer 4-10 or 4-35 can refer to a function of delivering an RLC SDU received from a lower layer directly to an upper layer out of sequence. The out-of-sequence delivery function of the NR RLC layer 4-10 or 4-35 can include a function of reassembling a plurality of RLC SDUs segmented from one RLC SDU and delivering the reassembled RLC SDU when the segmented RLC SDU is received. The out-of-sequence delivery function of the NR RLC layer 4-10 or 4-35 can include a function of recording a missing RLC PDU by storing an RLC SN or a PDCP SN of a received RLC PDU and reordering the received RLC PDU.

[0129] The NR MAC layer 4-15 or 4-30 can be connected to a plurality of NR RLC layers configured for one UE, and the functions of the NR MAC layer 4-15 or 4-30 can include some of the following functions:

[0130] - mapping between a logical channel and a transport channel

[0131] - multiplexing / demultiplexing of MAC SDUs

[0132] - scheduling information reporting

[0133] - error correction through HARQ

[0134] - priority handling between logical channels of one UE

[0135] - priority handling between UEs by means of dynamic scheduling

[0136] - MBMS service identification

[0137] - transport format selection

[0138] - padding.

[0139] The NR PHY layer 4-20 or 4-25 can encode and modulate an upper layer data channel into an OFDM symbol and transmit the OFDM symbol via a wireless channel, or can demodulate an OFDM symbol received via a wireless channel and channel-decode and deliver the OFDM symbol to an upper layer.

[0140] Figure 5 A UE according to an embodiment is shown.

[0141] Reference Figure 5 The UE includes a radio frequency (RF) processor 5-10, a baseband processor 5-20, a storage 5-30, and a controller 5-40.

[0142] The RF processor 5-10 can perform functions of transmitting and receiving signals via a radio channel, such as band conversion and amplification of signals. That is, the RF processor 5-10 up-converts a baseband signal provided from the baseband processor 5-20 into an RF band signal and then transmits the RF band signal via an antenna, and down-converts an RF band signal received via the antenna into a baseband signal. The RF processor 5-10 can include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a digital-to-analog converter (DAC), an analog-to-digital converter (ADC), etc.

[0143] Although only one antenna is illustrated in Figure 5 the UE can include a plurality of antennas. Also, the RF processor 5-10 can include a plurality of RF chains.

[0144] Also, the RF processor 5-10 can perform beamforming. For beamforming, the RF processor 5-10 can adjust phases and intensities of signals to be transmitted or received via a plurality of antennas or antenna elements, respectively. Also, the RF processor 5-10 can perform a MIMO operation and can receive a plurality of layers in the MIMO operation.

[0145] The baseband processor 5-20 converts between a baseband signal and a bit stream based on a physical entity specification of a system. For example, for data transmission, the baseband processor 5-20 generates complex symbols by encoding and modulating a transmission bit stream. For data reception, the baseband processor 5-20 reconstructs a received bit stream by demodulating and decoding a baseband signal provided from the RF processor 5-10.

[0146] For example, according to an OFDM scheme, for data transmission, the baseband processor 5-20 generates complex symbols by encoding and modulating a transmission bit stream, maps the complex symbols to subcarriers, and then configures OFDM symbols by performing inverse fast Fourier transform (IFFT) and cyclic prefix (CP) insertion. For data reception, the baseband processor 5-20 segments a baseband signal provided from the RF processor 5-10 into OFDM symbol units, reconstructs signals mapped to subcarriers by performing fast Fourier transform (FFT), and then reconstructs a received bit stream by demodulating and decoding the signals.

[0147] The baseband processor 5-20 and the RF processor 5-10 transmit and receive signals as described above. Accordingly, the baseband processor 5-20 and the RF processor 5-10 can be referred to as a transmitter, a receiver, a transceiver, or a communicator.

[0148] Also, at least one of the baseband processor 5-20 or the RF processor 5-10 can include a plurality of communication modules to support a plurality of different radio access technologies.

[0149] Further, at least one of the baseband processor 5-20 or the RF processor 5-10 can include different communication modules to process signals of different frequency bands. For example, different radio access technologies can include wireless local area network (LAN) (e.g., IEEE 802.11), cellular network (e.g., LTE), etc. Further, different frequency bands can include super high frequency (SHF) (e.g., 2.NRHz, NRHz) bands and millimeter wave (mmWave) (e.g., 60GHz) bands.

[0150] The storage 5-30 can store programs, applications, and data, such as configuration information, for operation of the UE. In particular, the storage 5-30 can store information associated with the second access node that performs wireless communication by using the second radio access technology. The storage 5-30 provides the stored data according to a request of the controller 5-40.

[0151] The controller 5-40 controls overall operations of the UE. For example, the controller 5-40 transmits and receives signals via the baseband processor 5-20 and the RF processor 5-10. Further, the controller 5-40 records or reads data on or from the storage 5-40. To this end, the controller 5-40 can include at least one processor. For example, the controller 5-40 can include a communication processor for controlling communication and an application processor (AP) for controlling an upper layer such as an application program.

[0152] Figure 6 An NR BS according to an embodiment is illustrated.

[0153] Reference Figure 6 The NR BS includes an RF processor 6-10, a baseband processor 6-20, a backhaul communicator 6-30, a storage 6-40, and a controller 6-50.

[0154] The RF processor 6-10 performs a function of transmitting and receiving a signal via a radio channel, e.g., band conversion and amplification of a signal. That is, the RF processor 6-10 up-converts a baseband signal provided from the baseband processor 6-20 into an RF band signal and then transmits the RF band signal via an antenna, and down-converts an RF band signal received via the antenna into a baseband signal. The RF processor 6-10 can include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, etc.

[0155] Although only one antenna is illustrated in Figure 6 The first access node can include a plurality of antennas. Further, the RF processor 6-10 can include a plurality of RF chains.

[0156] Further, the RF processor 6-10 can perform beamforming. For beamforming, the RF processor 6-10 can adjust phases and intensities of signals to be transmitted or received via a plurality of antennas or antenna elements, respectively. The RF processor 6-10 can perform a DL MIMO operation by transmitting one or more layers.

[0157] The baseband processor 6-20 converts between a baseband signal and a bit stream based on a physical entity specification of a first radio access technology. For example, for data transmission, the baseband processor 6-20 generates complex symbols by encoding and modulating a transmission bit stream. For data reception, the baseband processor 6-20 reconstructs a received bit stream by demodulating and decoding a baseband signal provided from the RF processor 6-10.

[0158] For example, according to an OFDM scheme, for data transmission, the baseband processor 6-20 generates complex symbols by encoding and modulating a transmission bit stream, maps the complex symbols to subcarriers, and then configures OFDM symbols by performing IFFT and CP insertion. For data reception, the baseband processor 6-20 segments a baseband signal provided from the RF processor 6-10 into OFDM symbol units, reconstructs signals mapped to subcarriers by performing FFT, and then reconstructs a received bit stream by demodulating and decoding the signals.

[0159] The baseband processor 6-20 and the RF processor 6-10 transmit and receive signals as described above. Accordingly, the baseband processor 6-20 and the RF processor 6-10 can be referred to as a transmitter, a receiver, a transceiver, a communicator, or a wireless communicator.

[0160] The backhaul communicator 6-30 provides an interface for communication with other nodes in a network. That is, the backhaul communicator 6-30 converts a bit stream transmitted from the master BS to another node (e.g., a secondary BS, a core network, etc.) into a physical signal, and converts a physical signal received from another node into a bit stream.

[0161] The storage 6-40 stores programs, application programs, and data, for example, configuration information, for operation of the master BS. Specifically, the storage 6-40 can store information about bearers allocated for connected UEs and measurement results reported from the connected UEs. Further, the storage 6-40 can store standard information for determining whether to provide a DC to a UE or release a DC from a UE. The storage 6-40 provides stored data according to a request of the controller 6-50.

[0162] The controller 6-50 controls overall operations of the BS. For example, the controller 6-50 transmits and receives signals via the baseband processor 6-20 and the RF processor 6-10, or the backhaul communicator 6-30. Also, the controller 6-50 records or reads data on or from the storage 6-40. To this end, the controller 6-50 can include at least one processor.

[0163] Figure 7 An NCR according to an embodiment is illustrated.

[0164] Referring to Figure 7 , the NCR can include an NCR-MT and an NCR-FWD. The NCR-MT can be configured to receive a control signal for NCR operation from a serving gNB and deliver control information to the NCR-FWD.

[0165] The NCR-FWD is configured to amplify an RF signal received from the gNB and transmit the amplified RF signal to the UE. Based on the control information received from the NCR-MT, the NCR-FWD can perform additional operations. The NCR-FWD can transmit the amplified signal to the UE or receive the transmitted signal from the UE by using a specific beam. Also, the NCR-FWD can perform or not perform reception / amplification / transmission of a signal from the gNB or reception / amplification / transmission of a signal from the UE according to a specific time division duplex (TDD) pattern.

[0166] Hereinafter, the NCR-MT is sometimes referred to as an MT, and the NCR-FWD is sometimes referred to as an FWD.

[0167] When the NCR MT experiences BF in a control link (C-link), the NCR FWD can perform an OFF operation.

[0168] According to an embodiment, the OFF operation can include a case where at least one of the operations described below is not performed.

[0169] The NCR-FWD does not perform a reception operation on a signal from the gNB in a backhaul link.

[0170] The NCR-FWD does not perform amplification / transmission of a signal received in an access link.

[0171] According to an embodiment, when an operation of a given access link's beam according to side control information for the NCR-FWD is performed, a forwarding operation of each beam is not performed.

[0172] When cell reselection is performed, the FWD can become OFF. However, after the FWD becomes OFF, there is no clear agreement on which configuration the FWD refers to for performing an ON operation.

[0173] Fast recovery of the FWD operation can be important for the UE served by the FWD. For example, if the FWD does not operate fast again, the time for which the served UE loses the signal can increase, and thus, the UE can have to perform a handover to another cell or experience unnecessary connection restriction due to declaration of radio link failure. In particular, the beam-related operation of the NCR is very short at the symbol level, thus sensitive to the time scale, and since the NCR can perform the forwarding operation fast, fast recovery of the FWD operation is important if possible.

[0174] In the BF, the same beam as the C-link can be used for the backhaul link. The BF in the C-link means that the signal corresponding to the forwarding source in the backhaul link is bad and unreliable. In this case, it is reasonable for the FWD to become OFF.

[0175] Since the detection of the BF inherits the operation of the UE, the MT can detect the BF in the C-link by itself. However, in order to recover the ON operation of the FWD, the BF must be recovered. With respect to the recovery from the BF, the time at which the MT detects the recovery can be different from the time at which the network detects the recovery. Thus, the time for the ON operation of the FWD and the recovery of the ON operation can vary depending on which entity recognizes the recovery from the BF.

[0176] The case in which an indicator associated with a specific BF occurs in a specific number or more can be defined as the BF. When the BF occurs, the MAC entity of the MT can notify the upper layer of the BF detection.

[0177] When the MT's upper layer receives the notification, the upper layer can indicate OFF to the FWD. The OFF indication can be implemented via one of the following methods.

[0178] Method 1

[0179] When the RRC layer of the NCR MT receives the notification of the BF detection from the MAC entity, the RRC layer of the MT can indicate OFF to the FWD. In this case, the MT can deliver an indicator indicating the occurrence of the BF of the NCR MT and / or an indicator indicating OFF of the FWD to the upper layer or the RRC layer.

[0180] Method 2

[0181] When the RRC layer of the MT receives the notification from the MAC entity, the MT can release or remove the NCR-side control information configuration information received from the gNB. In this case, according to the information being released or removed, the OFF operation of the FWD can vary.

[0182] For example, when the operation configuration with respect to the transmission / reception beam of the access link and the backhaul link is all released or removed from the NCR-side control information, the FWD can suspend both the reception and the transmission operation.

[0183] When the configuration information associated with the beam of the access link is removed from the NCR-side control information, the FWD can perform the reception operation but can suspend the transmission operation.

[0184] When the configuration associated with the aperiodic beam of the access link is removed from the NCR-side control information, the FWD can suspend only the operation associated with the aperiodic beam, not the operation of the semi / persistent beam.

[0185] Method 3

[0186] When the BF is detected regardless of the operation in the layer, the NCR forwarding operation can be suspended.

[0187] Methods 1 and 2 can be combined. For example, upon receiving the BF detection notification from the MAC entity, when the RRC layer of the MT indicates OFF to the FWD, the RRC layer of the MT can specify the configuration information to be released / removed from the side control information as detailed information, and can deliver the configuration information to the FWD.

[0188] After the MT detects the BF, the MAC entity and the PHY entity can perform a BF recovery operation. The BF recovery operation can include random access via a BF recovery-specific random access resource or a normal random access resource.

[0189] When the BF recovery is performed, the completion of the BF recovery that the MT can recognize can be available in the following cases:

[0190] Successful completion of a random access procedure for BF recovery; or

[0191] Completion of reception of a physical DL control channel (PDCCH) indicating a new UL grant or reception of a random access response (RAR) or contention resolution; or

[0192] Upon reception of a PDCCH indicating a new transmission UL grant for a HARQ process, the HARQ process is used for transmission of a BF recovery (BFR) MAC control element (CE) for the transmission / reception point (TRP)

[0193] Successful completion of a random access procedure for BF recovery; or

[0194] Reception of a PDCCH indicating completion of a new UL grant or reception of a RAR or contention resolution; or

[0195] Upon reception of a PDCCH indicating a new transmission UL grant for a HARQ process, the HARQ process is used for transmission of a BFR MAC CE for the TRP.

[0196] In this case, the network can transmit a response (e.g., RAR) on the transmission of the random access preamble, which is the random access attempt of the MT. The response can include DL control information (DCI) in the PDCCH, as described above.

[0197] Figure 8 A procedure for performing BF recovery at the MT side according to an embodiment is illustrated.

[0198] Reference Figure 8 When the MT detects the BF, the MT can find an available beam from the candidate beams, and can transmit a preamble in the configured RACH transmission time by using the beam. Thereafter, the MT can listen to a response delivered by the network (NW) during a preset time window. If the MT receives the RAR transmitted from the NW according to the listening, it is considered that the BF recovery is completed at the MT side.

[0199] However, in view of the NW, the NW can identify the completion of the BF recovery only upon confirming the successful reception of the RAR.

[0200] Therefore, there can be a method (Method A) of restoring the ON of the FWD in the BF recovery at the MT side, and a method (Method B) of receiving a recovery signal on the FWD ON from the network. In particular, in the latter case, the network can transmit a separate side control information after the BF recovery.

[0201] Method A: The MT automatically identifies the BF recovery, and thus restores the FWD ON.

[0202] In the case where the MT identifies the BF recovery, the MAC entity of the MT can notify the upper layer of the completion of the BF recovery of the MT. Here, the indication of the FWD ON or the FWD recovery can be additionally included therein.

[0203] The upper layer can indicate the FWD ON to the FWD.

[0204] In this case, the FWD can operate the FWD by using the latest side control information (i.e., the most recent side control information before the BF). The FWD can be operated by using the following configuration information:

[0205] - Using the access link beam configuration:

[0206] For periodic beams: The FWD will forward (restore) the received signal on each indicated beam and its corresponding time resource (symbol location in time and symbol duration for forwarding).

[0207] For aperiodic beams: On the beam newly indicated (before the BF) by the DCI, the received signal can be forwarded using the time resource configured before the BF.

[0208] - Use backhaul link beam configuration:

[0209] Semi-static beam: FWD will use UL / DL beam indicated by MAC CE before BF.

[0210] Adaptive beam: FWD uses the latest indicated by MAC CE and / or DCI for adaptive beam before BF.

[0211] - All time resources to be used are just after the time indicated by BFR.

[0212] If the previous OFF operation of FWD is Method 2 (e.g., the case of releasing specific side control information configuration information), Method A cannot be used. That is, when the OFF operation of FWD is Method 1 and Method 3, Method A can be used to restore FWD ON.

[0213] Method B: Method of restoring FWD ON based on information from the network.

[0214] When the MT recognizes that the BF restoration is complete, the FWD can still remain in the OFF state regardless of the time of recognition. However, when the network provides separate side control information, the FWD can simultaneously restore ON.

[0215] According to the type of side control information delivered, the following operations can be performed:

[0216] - New side control information of access link configuration via DL RRC message

[0217] - In this case, an operation is possible in which the beam indicated as a periodic beam of access link is ON during the indicated time.

[0218] - New side control information of backhaul link configuration via DL RRC message

[0219] - In this case, an operation is possible in which the beam indicated as a semi-static beam of backhaul is ON during the indicated time.

[0220] - If the configuration of the beam to be used on the existing C-link has been delivered via RRC or the use of a specific beam for the MT has been configured via MAC CE / DCI, after the configuration of the new C-link beam is delivered to the MT via RRC, even when a separate MAC CE and / or DCI regarding the semi-static beam of the backhaul link is not received, the currently used beam on the C-link can be used as a semi-static and / or adaptive beam of the NCR backhaul link.

[0221] According to another embodiment of the disclosure, in OFF of FWD, when the MT does not remove the previous sidelink control information configuration (Method 1 or 3), the network can indicate the ON indicator of FWD to the UE via DL RRC or DL MAC CE or DCI. In this case, the latest sidelink control information can be applied as the access / backhaul beam configuration in order to resume the FWD ON.

[0222] When the MT receives the new sidelink control information of the NW or the indication / message about FWD ON, the MT can indicate ON or resume ON to the FWD via a separate signal (e.g., RRC).

[0223] Figure 9 is a signal flow diagram illustrating a method of resuming FWD ON according to an embodiment. More specifically, Figure 9 is a signal flow diagram of Method A.

[0224] Referring to Figure 9 In step 901, the NCR is connected to the serving gNB.

[0225] In step 902, the serving gNB delivers the access link beam configuration information to the MT by providing the sidelink control information via a DL RRC message. The configuration of the beam to be used on the C-link can be additionally delivered. In step 903, the configuration information about the adaptive beam and / or the semi-static beam on the backhaul link can be notified in the DCI and / or MAC CE.

[0226] When receiving the beam information about the backhaul and access, the NCR can perform amplification and forwarding to the UE by performing FWD ON in step 904.

[0227] In step 905, when BF occurs on the C-link, the BF resume operation can be performed. The MT can search for the available C-link beam, and if the available C-link beam is found, the MT can deliver the RA preamble (RAP) to the serving gNB by using the beam by using the BF-specific or normal random access resource in step 906. The serving gNB can receive the preamble, and in step 907, can notify the MT of the UL grant and TA value by delivering the RAR to the MT.

[0228] In step 908, the MT can notify the gNB of the BF detection via the MAC CE by using the received TA and UL grant.

[0229] The serving gNB can check the MAC CE and then identify the BF. In step 909, the gNB can deliver the message 4 (msg 4) including the UL grant for the new UL data to the MT.

[0230] In step 910, the MT can identify that the BF is restored, and can inform the RRC layer of the MT of the BF restoration.

[0231] Upon receiving the notification, the RRC layer can indicate ON to the FWD in step 911.

[0232] Upon receiving the indication, the FWD can restore the ON by using the FWD side control information previously possessed in step 912. That is, the FWD can receive a signal in the backhaul link, and can amplify and deliver the signal on the configured beam of the access link.

[0233] In steps 914 and 913, in order to restore the BF, the gNB can additionally perform an operation of changing the beam on the C-link via the DL MAC CE and / or the DCI, and can deliver the side control information about the C-link and the access link by using the DL RRC message.

[0234] Figure 10 is a signal flow diagram illustrating a method of restoring the FWD ON based on information from the network according to an embodiment. More specifically, Figure 10 is a signal flow diagram of the method B.

[0235] Referring to Figure 10 , in step 1001, the NCR connects to the serving gNB.

[0236] In step 1002, the serving gNB delivers the access link beam configuration information by providing the side control information via the DL RRC message. In addition, the configuration of the beam to be used on the C-link can also be delivered. In step 1003, the configuration information about the adaptive beam and / or the semi-static beam on the backhaul link can be informed in the DCI and / or the MAC CE.

[0237] When both the information about the backhaul and the information about the access are received, the NCR can perform amplification and forwarding by performing the FWD ON in step 1004.

[0238] In step 1005, when the BF on the C-link occurs, the BF restoration operation can be performed. The MT can search for the available C-link beam, and if the available C-link beam is found, the MT can deliver the RAP to the serving gNB by using the beam by using the BF-specific or normal random access resource in step 1006.

[0239] The serving gNB can receive the preamble, and in step 1007, can inform the MT of the UL grant and the TA value by delivering the RAR to the MT.

[0240] In step 1008, the MT can inform the gNB of the BF detection via a MAC CE by using the received TA and UL grant.

[0241] The serving gNB can check the MAC CE, then identify the BF, and in step 1009, can deliver msg 4 including UL grant for new UL data to the MT.

[0242] In step 1010, side control information about the C-link and the access link can be delivered by using a DL RRC message. And in step 1011, for BF recovery, the gNB can additionally perform an operation of changing the beam on the C-link via a DL MAC CE and / or DCI.

[0243] Regardless of which new DL signal is delivered, the MT can perform FWD ON in response to the signal. For example, when the side control information including the beam configuration of the access link is first received via a DL RRC message, the FWD ON operation applied with the beam configuration of the access link can be performed.

[0244] (Case 1) When a DL MAC CE / DCI signal is received, in step 1012, the MT can perform FWD. Further, when a DL MAC CE / DCI signal for reconfiguration of the backhaul beam is received thereafter, the previously configured access link configuration can be maintained as is, and the configuration of the backhaul beam can be changed to perform the FWD ON operation.

[0245] (Case 2) When a DL MAC CE / DCI signal is received after BF recovery, in step 1013, the MT can perform FWD ON. In contrast, if a DL MAC CE / DCI signal for reconfiguration of the backhaul beam is first received after BF recovery, the new beam configuration of the backhaul is applied to FWD ON, and FWD can be turned ON by using the previous beam configuration of the access link.

[0246] After BF recovery, when initial side control information configuration information is received, the MT can indicate ON to FWD via RRC.

[0247] Upon receiving the indication, in step 1014, the FWD can override the previously obtained FWD side control information with the newly received side control information, thereby recovering FWD ON. That is, a signal can be received in the backhaul link, the received signal can be amplified, and the amplified signal can be delivered on the configured beam of the access link.

[0248] According to an embodiment of the disclosure, in case of BF detection in FWD OFF, the MAC entity of the MT can indicate the BF detection to the RRC layer, and the RRC layer can transmit the OFF indication to the FWD.

[0249] Alternatively, in case of BF detection, the MAC entity can directly transmit the OFF indication to the FWD, or the NCR can perform the OFF operation on the FWD regardless of the explicit indicator from the MAC entity to the RRC layer or the FWD.

[0250] According to an embodiment of the disclosure, after the BF, the NCR can perform a repetition operation via an optimal setting.

[0251] The method according to an embodiment of the disclosure as described in the claims or the specification can be implemented as hardware, software, or a combination of hardware and software.

[0252] When implemented as software, a computer-readable storage medium storing one or more programs (e.g., software modules) can be provided. The one or more programs stored in the computer-readable storage medium are configured to be executed by one or more processors in an electronic device. The one or more programs include instructions instructing the electronic device to execute the method according to an embodiment of the disclosure as described in the claims or the specification.

[0253] The program (e.g., software module or software) can be stored in a non-volatile memory including a random access memory (RAM) or a flash memory, a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), a magnetic disc storage device, an optical compact disc (CD)-ROM, a digital versatile disc (DVD), another optical storage device, or a magnetic cassette. Alternatively, the program can be stored in a memory including a combination of some or all of the above-mentioned storage media. In addition, a plurality of such memories can be included.

[0254] Further, the program can be stored in an attachable storage device which is accessible via any one or a combination of communication networks such as the Internet, an intranet, a LAN, a wide LAN (WLAN), a storage area network (SAN), etc. Such a storage device can access a device performing an embodiment of the disclosure via an external port. In addition, a separate storage device on the communication network can access the device performing an embodiment of the disclosure.

[0255] In the foregoing embodiments of the disclosure, elements included in the disclosure are expressed in singular or plural form according to an embodiment of the disclosure. However, the singular or plural form is appropriately selected for the convenience of description, and the disclosure is not limited thereto. As such, an element expressed in plural form can also be configured as a single element, and an element expressed in singular form can also be configured as a plurality of elements.

[0256] While specific embodiments of the present disclosure are described in the present disclosure, it is to be understood that various modifications can be made without departing from the scope of the present disclosure. Accordingly, the scope of the present disclosure is not limited to the embodiments described herein and should be defined by the appended claims and their equivalents.

[0257] According to an aspect of the present disclosure, a method performed by an NCR mobile terminal (MT) in a wireless communication system includes receiving sidelink control information including a forwarding configuration. The method includes transmitting, to an NCR forwarder, a first indication to stop forwarding in case of a beam failure. The method includes initiating a beam failure recovery procedure for the NCR MT. The method includes transmitting, to the NCR forwarder, a second indication to resume forwarding by using the forwarding configuration in case of successful completion of the beam failure recovery procedure.

[0258] According to an embodiment of the present disclosure, the second indication includes an indication to use a latest forwarding configuration before the beam failure.

[0259] According to an embodiment of the present disclosure, the method further includes detecting the beam failure in a control link.

[0260] According to an embodiment of the present disclosure, the beam failure recovery includes a random access procedure.

[0261] According to an embodiment of the present disclosure, the NCR MT includes a medium access control (MAC) entity, and the first indication is transmitted by the MAC entity.

[0262] According to an aspect of the present disclosure, an NCR MT includes a transceiver and at least one processor. The at least one processor is configured to receive sidelink control information including a forwarding configuration. The at least one processor is configured to transmit, to an NCR forwarder, a first indication to stop forwarding in case of a beam failure. The at least one processor is configured to initiate a beam failure recovery procedure for the NCR MT. The at least one processor is configured to transmit, to the NCR forwarder, a second indication to resume forwarding by using the forwarding configuration in case of successful completion of the beam failure recovery procedure.

[0263] According to an aspect of the present disclosure, a method performed by an NCR forwarder in a wireless communication system includes receiving, from an NCR MT, a first indication to stop forwarding in case of a beam failure. The method includes receiving, from the NCR MT, a second indication to resume forwarding by using a forwarding configuration in case of successful completion of a beam failure recovery procedure, wherein the forwarding configuration is received before the beam failure.

[0264] According to one aspect of the disclosure, there is provided an NCR forwarding comprising a transceiver and at least one processor. The at least one processor is configured to receive, from an NCR MT, a first indication to stop forwarding in case of a beam failure. The at least one processor is configured to receive, from the NCR MT, a second indication to resume forwarding by using a forwarding configuration in case of a successful completion of a beam failure recovery procedure, wherein the forwarding configuration is received prior to the beam failure.

Claims

1. A method performed by a network-controlled repeater (NCR) mobile terminal (MT) in a wireless communication system, the method comprising: receiving sidelink control information including a forwarding configuration; in case of occurrence of a beam failure, sending a first indication to an NCR forwarder to stop forwarding; initiating a beam failure recovery procedure for the NCR MT; in case of successful completion of the beam failure recovery procedure, sending a second indication to the NCR forwarder to resume forwarding by using the forwarding configuration. 2.The method of claim 1, wherein the second indication including an indication to use a latest forwarding configuration before the beam failure. 3.The method of claim 1, the method further comprising detecting the beam failure in a control link. 4.The method of claim 1, wherein, the beam failure recovery procedure including a random access procedure. 5.The method of claim 1, wherein the NCR MT including a medium access control (MAC) entity, and wherein the first indication is sent by the MAC entity. 6.A network-controlled repeater (NCR) mobile terminal (MT) in a wireless communication system, the NCR MT comprising: a transceiver; and at least one processor configured to: receive sidelink control information including a forwarding configuration, in case of occurrence of a beam failure, send a first indication to an NCR forwarder to stop forwarding, initiate a beam failure recovery procedure for the NCR MT, in case of successful completion of the beam failure recovery procedure, send a second indication to the NCR forwarder to resume forwarding by using the forwarding configuration. 7.The NCR MT of claim 6, wherein the second indication including an indication to use a latest forwarding configuration before the beam failure.

8. The NCR MT of claim 6, wherein, the at least one processor further configured to: detect the beam failure in a control link. 9.The NCR MT of claim 6, wherein the beam failure recovery procedure including a random access procedure. 10.The NCR MT of claim 6, wherein the NCR MT including a medium access control (MAC) entity, and wherein the first indication is sent by the MAC entity. 11.A method performed by a network-controlled repeater (NCR) forwarder in a wireless communication system, the method comprising: in case of occurrence of a beam failure, receiving a first indication from an NCR mobile terminal (MT) to stop forwarding; and in case of successful completion of a beam failure recovery procedure, receiving a second indication from the NCR MT to resume forwarding by using a forwarding configuration; wherein the forwarding configuration is received before the beam failure. 12.The method of claim 11, the second indication including an indication to use a latest forwarding configuration before the beam failure. wherein, 13.The method of claim 11, the beam failure is detected in a control link. wherein 14.The method of claim 11, the beam failure recovery procedure including a random access procedure. wherein 15.The method of claim 11, ​ wherein The first indication is received from a medium access control (MAC) entity of the NCR MT. The first indication is received from a medium access control (MAC) entity of the NCR MT.

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