Method and apparatus for notifying beam failure recovery in a wireless communication system

Abstract

This disclosure provides a method for performing beam fault detection and recovery performed by a user equipment (UE), the method comprising: receiving configuration information for beam fault detection and recovery from a base station (BS); detecting a beam fault for a specific cell (SpCell) or a secondary cell (Scell) based on the configuration information; and, based on the detection result, transmitting a BFR MAC CE via a random access procedure or on an uplink (UL) resource or scheduling request (SR) resource for transmitting a beam fault recovery (BFR) media access control (MAC) control element (CE) (BFR MAC CE), wherein the BFR MAC CE includes information about whether a beam fault for the SpCell was detected or not.

Description

Technical Field

[0001] This disclosure relates to a method for instructing beam fault recovery for a specific cell (SpCell) in a wireless communication system. Background Technology

[0002] Given the increasing demand for wireless data traffic following the commercialization of fourth-generation (4G) communication systems, the industry is continuously striving to develop fifth-generation (5G) communication systems, or pre-5G communication systems. For this reason, 5G or pre-5G communication systems are referred to as "beyond 4G network" communication systems or "post-LTE" systems. To achieve high data rates, the implementation of 5G communication systems in ultra-high frequency (UHF) or millimeter-wave (mmWave) bands (e.g., the 60 GHz band) is currently being considered. To reduce radio wave path loss and increase transmission distance in UHF bands, various technologies are being researched, including beamforming, massive MIMO, full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and massive MIMO. To improve the system network of 5G communication systems, various technologies have been developed, such as evolved small cells, advanced small cells, cloud radio access networks (cloud-RAN), ultra-dense networks, device-to-device communication (D2D), wireless backhaul, mobile networks, cooperative communication, coordinated multipoint (CoMP), and interference cancellation. Furthermore, for 5G communication systems, advanced coding and modulation (ACM) technologies such as hybrid frequency shift keying (FSK) and quadrature amplitude modulation (QAM) (FQAM) and sliding window superposition coding (SWSC) have been developed, as well as advanced access technologies such as filter bank multicarrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA).

[0003] The internet has evolved from a human-based interconnected network for creating and consuming information to the Internet of Things (IoT). In the IoT, distributed components such as objects exchange information to process it. Currently, the Internet of Everything (IoE) technology has emerged, combining IoT technology with technologies such as connecting to cloud servers to process big data. To realize the IoT, various technological elements are needed, such as sensing technology, wired / wireless communication and network infrastructure, service interface technology, and security technology. Therefore, in recent years, research has been conducted on technologies related to sensor networks for connecting objects, machine-to-machine (M2M) communication, and machine-type communication (MTC). In the IoT environment, intelligent internet technology (IT) services can be provided to collect and analyze data obtained from connected objects, thereby creating new value for human life. With the convergence and integration of existing information technology (IT) and various industries, the IoT may be applied to various fields, such as smart homes, smart buildings, smart cities, smart cars or connected cars, smart grids, healthcare, smart home appliances, and advanced medical services.

[0004] Therefore, various attempts are underway to apply 5G communication systems to IoT networks. For example, technologies related to sensor networks, M2M communication, and MTC are being implemented using 5G communication technologies such as beamforming, MIMO, and array antennas. As an application of the aforementioned big data processing technologies, cloud radio access networks (cloud-RAN) can also be seen as an example of the integration of 5G and IoT technologies.

[0005] Specifically, with the development of wireless communication systems, there is a need for an efficient method to indicate beam fault recovery for specific cells (SpCells). Summary of the Invention

[0006] Technical issues

[0007] This disclosure relates to a method for instructing beam fault recovery for a cell.

[0008] Problem Solution

[0009] According to embodiments of this disclosure, an apparatus and method for efficiently providing services in a wireless communication system are provided.

[0010] The advantages and effects of this disclosure

[0011] According to embodiments of this disclosure, an apparatus and method for efficiently providing services in a wireless communication system are provided. Attached Figure Description

[0012] Figure 1A This is a diagram illustrating the structure of a novel radio (NR) system according to an embodiment of the present disclosure.

[0013] Figure 1B This is a diagram illustrating the radio protocol architecture of Long Term Evolution (LTE) and NR systems according to embodiments of this disclosure.

[0014] Figure 1C This is a diagram illustrating a contention-based four-step random access procedure performed by a UE for a base station (BS) according to an embodiment of this disclosure.

[0015] Figure 1D This is a diagram illustrating a two-step random access procedure performed by a UE against a BS according to an embodiment of this disclosure.

[0016] Figure 1E This is a diagram illustrating an example of the downlink (DL) and uplink (UL) channel frame structure when beam-based communication is performed in an NR system according to an embodiment of the present disclosure.

[0017] Figure 1F This is a diagram illustrating an example of a message to be sent to the BS when the UE performs beam fault recovery for a special cell (SpCell) according to an embodiment of this disclosure.

[0018] Figure 1G This is a diagram illustrating a first example of UE operation when the UE performs beam fault detection and recovery for SpCell according to an embodiment of the present disclosure.

[0019] Figure 1H This is a diagram illustrating a second example of UE operation when the UE performs beam fault detection and recovery for SpCell according to an embodiment of the present disclosure.

[0020] Figure 1I This is a block diagram illustrating the construction of a UE according to an embodiment of the present disclosure.

[0021] Figure 1J This is a block diagram illustrating the construction of a BS according to an embodiment of the present disclosure. Detailed Implementation

[0022] Best mode

[0023] According to one embodiment of the present invention, a method for performing beam fault detection and recovery performed by a user equipment (UE) may include: receiving configuration information regarding beam fault detection and recovery from a base station (BS); detecting a beam fault for a specific cell (SpCell) or secondary cell (Scell) based on the configuration information; and, based on the detection result, transmitting a BFR MAC CE via a random access procedure or on an uplink (UL) resource or scheduling request (SR) resource for transmitting a beam fault recovery (BFR) media access control (MAC) control element (CE) (BFR MAC CE), wherein the BFR MAC CE includes information regarding whether a beam fault for the SpCell was detected or not.

[0024] The transmission of BFR MAC CE may include: when a beam fault for SCell is detected, determining whether there is a UL resource for transmitting BFR MAC CE; when the UL resource exists, transmitting BFR MAC CE on the UL resource, and when the UL resource does not exist, transmitting BFR MAC CE on an SR resource for transmitting BFR MAC CE or via a random access procedure.

[0025] Sending a BFR MAC CE on a UL resource may also include instructions to reuse and assemble entities to generate a BFR MAC CE.

[0026] The transmission of BFR MAC CE may include: triggering a random access procedure when a beam fault is detected for SpCell; and transmitting the BFR MAC CE via the random access procedure.

[0027] Sending a BFR MAC CE via a random access procedure may include, when the random access procedure is a two-step random access procedure, instructing the multiplexing and assembling entity to include the BFR MAC CE in message A (MSG A), and sending the BFR MAC CE via MSG A.

[0028] Sending a BFR MAC CE via a random access procedure may include, when the random access procedure is a 4-step random access procedure, instructing the multiplexing and assembly entity to include the BFR MAC CE in Msg 3, and sending the BFR MAC CE via Msg 3.

[0029] BFR MAC CE may also include one or more serving cell identifiers and details of the serving cells corresponding to the one or more serving cell identifiers.

[0030] The details of the serving cell may include an available candidate (AC) field, and the AC field of the serving cell details may indicate whether information about the beams that can be used for additional beam recovery is included in the details of the serving cell.

[0031] The first identifier of one or more serving cell identifiers can indicate information about whether a beam fault for SpCell was detected or not.

[0032] When the first identifier indicates that a beam fault for SpCell has been detected, the BFR MAC CE may not include details of the serving cell.

[0033] According to one embodiment of the present invention, a user equipment (UE) for performing beam fault detection and recovery may include: a transceiver; a processor coupled to the transceiver and configured to receive configuration information regarding beam fault detection and recovery from a base station (BS), detect beam faults for a specific cell (SpCell) or a secondary cell (Scell) based on the configuration information, and, based on the detection result, transmit a BFR MAC CE via a random access procedure or on an uplink (UL) resource or scheduling request (SR) resource for transmitting a beam fault recovery (BFR) media access control (MAC) control element (CE) (BFR MAC CE), wherein the BFR MAC CE includes information regarding whether a beam fault for the SpCell has been detected or not.

[0034] The processor can also be configured to trigger a random access procedure and send a BFR MAC CE via the random access procedure when a beam fault for SpCell is detected.

[0035] The processor can also be configured to instruct the multiplexing and assembling entity to include the BFR MAC CE in MSG A and transmit the BFR MAC CE via MSG A when the random access procedure is a 2-step random access procedure, and to instruct the multiplexing and assembling entity to include the BFR MAC CE in Msg 3 and transmit the BFR MAC CE via Msg 3 when the random access procedure is a 4-step random access procedure.

[0036] BFR MAC CE may also include one or more serving cell identifiers and details of the serving cells corresponding to the one or more serving cell identifiers.

[0037] The first identifier in one or more serving cell identifiers may indicate information about whether a beam fault for SpCell has been detected or not, and when the first identifier indicates that a beam fault for SpCell has been detected, the BFRMAC CE may not include details of the serving cell.

[0038] This publicly disclosed model

[0039] The operating principles of this disclosure will be described in detail below with reference to the accompanying drawings. Well-known functions or configurations are not described in detail in the following description of this disclosure, as such details would obscure the disclosure. The terminology used in this specification is defined with reference to the functions used in this disclosure and may vary depending on the intent of the operator and user or known methods. Therefore, the definitions of the terms should be understood based on the overall description of this application.

[0040] In the following description, terms identifying access nodes, indicating network entities or network functions (NFs), indicating messages, indicating interfaces between network entities, and indicating various identifying information are exemplified for the purpose of description. Therefore, this disclosure is not limited to the terms described below, and other terms indicating objects having the same technical meaning may be used.

[0041] The advantages and features of this disclosure and its implementation methods can be more readily understood by referring to the following detailed description of embodiments and the accompanying drawings. However, this disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concepts of this disclosure to those skilled in the art. Therefore, the scope of this disclosure is defined by the appended claims. Throughout the specification, similar reference numerals refer to similar elements.

[0042] It should be understood that each block in a flowchart, and combinations of blocks in a flowchart, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus, so that the instructions, which execute through the processor of the computer or other programmable data processing apparatus, can generate means for performing the functions specified in the flowchart blocks. These computer program instructions can also be stored in a computer-executable or computer-readable storage medium, which can instruct the computer or other programmable data processing apparatus to operate in a particular manner, thereby enabling the instructions stored in the computer-executable or computer-readable storage medium to generate an article of work comprising instruction means for performing the functions specified in the flowchart blocks. 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 data processing apparatus, thereby generating a computer-implementable process, such that the instructions, which execute on the computer or other programmable data processing apparatus, provide operations for implementing the functions specified in one or more flowchart blocks.

[0043] Furthermore, each box in the flowchart illustration may represent a module, segment, or code section, which includes one or more executable instructions for performing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the boxes may not appear in the stated order. For example, two boxes shown consecutively may actually be executed substantially simultaneously, or these boxes may sometimes be executed in reverse order depending on the functions involved.

[0044] In this embodiment, the term "...unit" refers to a software or hardware component that performs certain tasks, such as a field-programmable gate array (FPGA) or an application-specific integrated circuit (ASIC). However, the term "...unit" is not limited to software or hardware. The "...unit" may be configured to reside in addressable storage media or to operate one or more processors. Therefore, according to one embodiment, "...unit" may include, for example, components such as software components, object-oriented software components, class components and task components, processes, functions, attributes, programs, subroutines, program code segments, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functionality provided in elements and "...units" may be combined into fewer elements and "...units," or further separated into additional elements and "...units." Furthermore, elements and "...units" may be implemented as one or more central processing units (CPUs) in an operating device or secure multimedia card. Additionally, according to one embodiment, "...unit" may include one or more processors.

[0045] In the description of this disclosure, detailed descriptions of related technologies are omitted where it is thought that they might unnecessarily obscure the essence of this disclosure. Hereinafter, embodiments of this disclosure will now be described with reference to the accompanying drawings.

[0046] In the following description, terms identifying access nodes, network entities or network functions (NFs), messages, interfaces between network entities, and various identifying information are exemplified for ease of description. Therefore, this disclosure is not limited to the terms described below, and other terms indicating objects having the same technical meaning may be used. For example, in the following description, user equipment (UE) may refer to the media access control (MAC) entity in the UE present in each of the primary cell group (MCG) and secondary cell group (SCG) described below.

[0047] In the following text, for ease of description, some terms and names defined in the 3GPP LTE standard may be used. However, this disclosure is not limited to these terms and names and may be equally applied to systems conforming to other standards.

[0048] In the following description, a base station is an entity that allocates resources to a terminal and can be a next-generation node B (gNode B), an evolved Node B (eNode B), a node B, a base station (BS), a radio access unit, a BS controller, or a node on a network. A terminal can include a UE, a mobile station (MS), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing communication functions. However, this disclosure is not limited to the examples described above.

[0049] Specifically, this disclosure can be applied to 3GPP New Radio (NR) (5th generation (5G) mobile communication standard). Furthermore, this disclosure can also be applied to smart services based on 5G communication technology and Internet of Things (IoT) technology (e.g., smart homes, smart buildings, smart cities, smart or connected cars, healthcare, digital education, retail, security and safety services). In this disclosure, for ease of description, eNB and gNB can be used interchangeably. That is, the BS described by eNB can represent gNB. Furthermore, the term "terminal (UE)" can refer not only to mobile phones, NB-IoT devices, and sensors, but also to other wireless communication devices.

[0050] Wireless communication systems that provide early voice-based services are being developed into broadband wireless communication systems that provide high-speed and high-quality packet data services, based on communication standards such as High-Speed ​​Packet Access (HSPA), Long Term Evolution (LTE) or Evolved Universal Terrestrial Radio Access (E-UTRA), LTE-Advanced (LTE-A), 3GPP's LTE-Pro, High-Speed ​​Packet Data (HRPD), 3GPP2's Ultra Mobile Broadband (UMB), and the Institute of Electrical and Electronics Engineers (IEEE) 802.16e communication standard.

[0051] As a representative example of a broadband wireless communication system, the LTE system employs Orthogonal Frequency Division Multiplexing (OFDM) for the downlink (DL) and Single-Carrier Frequency Division Multiple Access (SC-FDMA) for the uplink (UL). UL refers to the radio link used to transmit data or control signals from a terminal (e.g., UE or MS) to a base station (e.g., eNB or BS), and DL refers to the radio link used to transmit data or control signals from the base station to the terminal. The aforementioned multiple access scheme identifies each user's data or control information by allocating and managing time-frequency resources for carrying each user's data or control information to ensure they do not overlap, i.e., achieving orthogonality between them.

[0052] As a post-LTE communication system, namely 5G communication system, it needs to support services that can freely reflect and simultaneously meet the diverse needs of users, service providers, and others. Services considered for 5G systems include enhanced mobile broadband (eMBB), massive machine-type communications (mMTC), and ultra-reliable low-latency communications (URLLC) services.

[0053] According to some embodiments, eMBB is designed to provide data rates higher than those supported by traditional LTE, LTE-A, or LTE-Pro. For example, in a 5G communication system, eMBB should be able to provide a peak data rate of 20Gbps in DL and a peak data rate of 10Gbps in UL at a single BS. Furthermore, the 5G communication system must simultaneously provide the peak data rate for the UE and the increased user-aware data rate. To meet these requirements, improvements to the transmission and reception technologies in 5G communication systems are needed, including improved multiple-input multiple-output (MIMO) transmission techniques. Moreover, the data rates required in 5G communication systems can be met by using frequency bandwidths higher than 20MHz in the 3GHz to 6GHz or 6GHz or higher frequency bands, rather than by using a maximum of 20MHz for LTE transmission within the 2GHz band.

[0054] mMTC is considering simultaneously supporting IoT application services such as those within 5G communication systems. To effectively deliver IoT, mMTC may require support for a large number of terminals within a cell, improved terminal coverage, improved battery life, and reduced terminal costs. Since IoT connects to various sensors and devices to provide communication capabilities, mMTC should be able to support a large number of terminals within a cell (e.g., 1,000,000 terminals / km). 2 Furthermore, since mMTC-enabled terminals are likely to be located in shadow areas not covered by cell coverage, such as building basements, they may require wider coverage than other services offered by 5G communication systems due to the nature of the services. mMTC-enabled terminals should be configured as low-cost devices, and due to the difficulty in frequently replacing their batteries, they may require a very long battery life of 10 to 15 years.

[0055] Finally, URLLC refers to cellular-based wireless communication services for mission-critical purposes, such as remote control of robots or machinery, industrial automation, unmanned aerial vehicles, telemedicine, and emergency alerts. Therefore, URLLC should provide communication with very low latency (ultra-low latency) and very high reliability (ultra-reliable reliability). For example, services supporting URLLC should meet an air interface latency of less than 0.5 milliseconds while requiring 10... -5 Or a smaller packet error rate. Therefore, for services that support URLLC, 5G systems should provide smaller transmission time intervals (TTIs) than other services, and may also have design requirements for allocating wide resources within the frequency band to ensure the reliability of the communication link.

[0056] In 5G communication systems, the three services considered—eMBB, URLLC, and mMTC—can be multiplexed and transmitted within a single system. In this document, to meet the different service requirements, services may employ different transmit / receive schemes and parameters. However, the aforementioned mMTC, URLLC, and eMBB services are merely examples, and the types of services to which this disclosure applies are not limited to these.

[0057] In the following text, for ease of description, this disclosure uses the terms and names defined in the LTE and NR standards, which are the most recent standards defined in the 3GPP standards among current communication standards. However, this disclosure is not limited to these terms and names and can be equally applied to systems conforming to other standards. Specifically, this disclosure can be applied to 3GPP NR (or 5G mobile communication standards). Furthermore, embodiments of this disclosure can be applied to other communication systems with similar technical backgrounds or channel types. Moreover, based on the determination of those skilled in the art, embodiments of this disclosure can be adapted to other communication systems with partial modifications without significantly departing from the scope of this disclosure.

[0058] The following section presents a procedure in which the UE generates a MAC control element (MAC CE) as a control message for the MAC layer to notify beam fault recovery for a specific cell (SpCell) in a wireless communication system, and details the message format.

[0059] In this disclosure, the BS can clearly detect the reason why the UE performs random access, thereby providing the UE with the required additional beam-related configuration, enabling seamless communication in a beam-based communication system.

[0060] Figure 1A This is a diagram illustrating the structure of an NR system according to an embodiment of the present disclosure. (Refer to...) Figure 1A The wireless communication system may include multiple BS1a-05, 1a-10, 1a-15, and 1a-20, Access and Mobility Management Function (AMF) 1a-20, and User Plane Function (UPF) 1a-30. The UE (or terminal) 1a-35 may access an external network via BS1a-05, 1a-10, 1a-15, or 1a-20 and UPF 1a-30. However, the wireless communication system is not limited to... Figure 1A Examples, and can include more than Figure 1A The number of elements shown may be more or less.

[0061] BS1a-05, 1a-10, 1a-15, and 1a-20 are access nodes in a cellular network and can provide radio access to UEs accessing the network. That is, BS1a-05, 1a-10, 1a-15, and 1a-20 can collect status information such as UE buffer status, available transmit power status, and channel status, and can perform scheduling to support the connection between the UE and the core network (CN), thereby serving user traffic. Communication systems, including NR systems, can be configured to handle traffic by dividing it into a user plane (UP) related to the transmission of actual user data and a control plane (CP) related to connection management. In the diagram, gNB 1a-05 and 1a-20 can use the UP and CP related technologies defined in NR technology, and ng-eNB 1a-10 and 1a-15 connected to 5GC can use the UP and CP related technologies defined in LTE technology.

[0062] AMF (or SMF) 1a-25 can be an entity that performs mobility management functions and various control functions for the UE and can be connected to multiple BSs, while UPF 1a-30 can be a gateway to provide data transmission.

[0063] Figure 1B This is a diagram illustrating the radio protocol architecture of LTE and NR systems according to embodiments of this disclosure.

[0064] Reference Figure 1B The radio protocol architecture of an LTE system may include Packet Data Convergence Protocol (PDCP) layers (or entities) 1b-05 and 1b-40, Radio Link Control (RLC) layers (or entities) 1b-10 and 1b-35, and MAC layers (or entities) 1b-15 and 1b-30 for UE and eNB, respectively.

[0065] PDCP layer 1b-05 or 1b-40 can perform Internet Protocol (IP) header compression / decompression, and RLC layer 1b-10 or 1b-35 can reconfigure PDCP Protocol Data Units (PDUs) to an appropriate size.

[0066] MAC layer 1b-15 or 1b-30 can connect to multiple RLC layers configured for a UE and can multiplex RLC PDUs into MAC PDUs and demultiplex RLC PDUs from MAC PDUs.

[0067] The physical (PHY) layer 1b-20 or 1b-25 can encode and modulate upper-layer data channels into OFDM symbols and transmit them via a radio channel, or demodulate OFDM symbols received via a radio channel, perform channel decoding on the OFDM symbols, and deliver them to the upper layer. Furthermore, the physical layer can use Hybrid Automatic Repeat Request (HARQ) for additional error correction, and the receiver can send information in one bit regarding whether it has received a packet from the transmitter. This can be referred to as HARQ ACK / NACK information.

[0068] In LTE systems, DL HARQ ACK / NACK information for UL data transmission can be transmitted on the Physical Hybrid ARQ Indicator Channel (PHICH). In NR systems, DL HARQ ACK / NACK information can be provided based on UE scheduling information on the Physical Dedicated Control Channel (PDCCH) (the channel on which DL / UL resource allocation is transmitted). That is, in NR systems, the BS or UE can determine via the PDCCH whether a retransmission or new transmission of UL data is requested. This is because asynchronous HARQ is applied in NR systems. UL HARQ ACK / NACK information for downlink data transmission can be transmitted via the Physical Uplink Control Channel (PUCCH) or the Physical Uplink Shared Channel (PUSCH). Typically, the PUCCH is transmitted in the UL of the primary cell (PCell), but when supported by the UE, the BS can allow the secondary cell (SCell) to additionally transmit it to the UE, referred to as the PUCCH SCell.

[0069] Although not shown in the diagram, the Radio Resource Control (RRC) layer can exist above the PDCP layer of both the UE and the BS, and each of the RRC layers can send or receive configuration control messages related to access and measurement to control radio resources. For example, the BS can instruct the UE to perform measurements using messages from the RRC layer, and the UE can report measurement results to the BS using messages from the RRC layer.

[0070] The PHY layer can be configured to use one or more frequencies / carriers, and the technique of configuring and using multiple frequencies simultaneously within a single BS is called carrier aggregation (CA). Communication between the UE (or terminal) and the BS (eNB in ​​LTE or gNB in ​​NR) uses only one carrier, but with CA, a primary carrier and one or more subcarriers are additionally used, significantly increasing the data transmission volume to match the number of subcarriers. In LTE systems, the cell using the primary carrier within a BS is called a PCell, and the cell using the secondary carrier is called an SCell. The technique where CA functionality is extended to two BSs is called dual connectivity (DC). With DC, the UE simultaneously connects to and uses both a primary BS (primary E-UTRAN NodeB (MeNB)) and a secondary BS (secondary E-UTRAN NodeB (SeNB)). Cells included in the primary BS are called primary cell groups (MCGs), and cells included in the secondary BS are called secondary cell groups (SCGs). Each cell group has a representative cell, and the representative cell of the MCG is called the primary cell (PCell), and the representative cell of the SCG is called the primary-secondary cell (PSCell). When using the aforementioned NR, the UE can use LTE technology in the MCG and NR in the SCG, thus using both LTE and NR simultaneously. In NR, each cell group (i.e., MCG or SCG) can have a maximum of 16 serving cells (PCell and SCell of the MCG; PSCell and SCell of the SCG).

[0071] Figure 1C This is a diagram illustrating a contention-based four-step random access procedure performed by the UE for the NB in ​​various situations requiring initial access, re-access, handover, and other random access, according to embodiments of this disclosure.

[0072] To access NB 1c-03, UE 1c-01 according to Figure 1C A Physical Random Access Channel (PRACH) is selected, and a random access preamble is sent to the corresponding PRACH (1c-11). According to embodiments of this disclosure, one or more UEs 1c-01 can simultaneously send random access preambles on PRACH resources. The PRACH resource can be on a single subframe or can use only some symbols within a single subframe.

[0073] Furthermore, according to embodiments of this disclosure, information regarding PRACH resources can be included in system information broadcast by NB 1c-03, thus allowing the UE to identify on which time and frequency resources the preamble should be transmitted. Additionally, the random access preamble is a specific sequence specifically designed to be received even when transmitted before full synchronization with NB 1c-03, and multiple preamble identifiers (indexes) can exist according to the standard. When multiple preamble identifiers exist, the preamble to be transmitted by UE 1c-01 can be randomly selected by the UE or a specific preamble specified by NB 1c-03.

[0074] When NB 1c-03 receives the preamble, NB 1c-03 sends a Random Access Response (RAR) message (also known as Msg2) (1c-21) to UE 1c-01 in response. The RAR message may include identifier information about the preamble used in operation 1c-11, and may include UL transmission timing correction information, as well as UL resource allocation information and temporary UE identifier information to be used in subsequent operations (i.e., 1c-31).

[0075] According to embodiments of this disclosure, when multiple UEs send different preambles in Operation 1c-11 to attempt random access, the RAR message may include a response to each preamble and may send identifier information about the preamble to indicate which preamble the corresponding response is for. The UL resource allocation information included in each response to each preamble may be detailed information about the resources to be used by the UE in Operation 1c-31, and may include the physical location and size of the resources, the modulation and coding scheme (MCS) used for transmission, and control information about power during transmission. When a UE that has already sent a preamble performs initial access, the UE does not have an identifier assigned by the BS for communicating with the BS; temporary UE identifier information may be a value sent for this purpose.

[0076] On the other hand, RAR messages may include responses to each preamble(s) and may optionally include a backoff indicator (BI). When a random access preamble needs to be retransmitted because it was not successfully executed, the backoff indicator may be a value that is sent to randomly delay transmission according to that value of the backoff indicator, without immediately retransmitting the preamble.

[0077] More specifically, when the UE fails to receive the RAR correctly, or when the contention resolution described below is not correctly implemented, the UE may have to retransmit the random access preamble. In this case, the backoff indicator value can be indicated by the index value, and the UE can select a random value within the range of 0 to the index value, and can retransmit the random access preamble after the time corresponding to that value. For example, when BS indicates 5 (i.e., 60ms) as the BI value and the UE randomly selects a value of 23ms from 0ms to 60ms, the selected value is stored in a variable named PREAMBLE_BACKOFF, and the UE executes the procedure to retransmit the preamble after 23ms. If no backoff indicator is sent, the UE can directly transmit the random access preamble when it needs to be retransmitted due to unsuccessful execution.

[0078] [Table 1]

[0079]

[0080]

[0081] RAR messages must be sent within a certain time period starting from a certain time after the preamble is sent, and this time period starting after the preamble is sent is called the "RAR window". The RAR window can be a time period starting from a point in time after the preamble has been sent. This specific time can be the time when the PDCCH used to schedule RAR messages is first detected. Furthermore, the length of the RAR window can be a value configured by the BS for each PRACH resource or one or more PRACH resource sets in the system information message broadcast by the BS. When a RAR message is sent, the BS schedules the corresponding RAR message on the PDCCH and can scramble the corresponding scheduling information using a Random Access Radio Network Temporary Identifier (RA-RNTI). The RA-RNTI is mapped to the PRACH resource used to send messages in Operation 1c-11, and a UE that has already sent a preamble on a specific PRACH resource can attempt to receive the PDCCH based on the RA-RNTI and can determine whether a corresponding RAR message exists. When a RAR message is a response to a preamble sent by the UE in Operation 1c-11, as shown in the example diagram, the RA-RNTI used for RAR message scheduling information includes information about the transmission in Operation 1c-11. Therefore, the RA-RNTI can be calculated using the following equation. However, the invention is not limited to the following example: RA-RNTI = 1 + s_id + 14 × t_id + 14 × 80 × f_id + 14 × 80 × 8 × ul_carrier_id (Equation 1)

[0082] In this paper, s_id is the index corresponding to the first OFDM symbol on which the transmission of the preamble sent in Operation 1c-11 begins, and can have a value of 0 ≤ s_id < 14 (i.e., the maximum number of OFDMs in a time slot).

[0083] In addition, t_id is the index corresponding to the first time slot, on which the transmission of the preamble sent in Operation 1c-11 begins, and can have a value of 0 ≤ t_id < 80 (i.e., the maximum number of time slots in a system frame (10ms)).

[0084] Furthermore, f_id indicates which PRACH on the frequency the preamble transmitted in operation 1c-11 is transmitted on, and can have a value of 0 ≤ f_id < 8 (i.e., the maximum number of PRACH on the frequency in the same time period).

[0085] ul_carrier_id can be a parameter used to identify whether the preamble is sent in the normal uplink (NUL) (0 in this case) or the preamble is sent in the supplementary uplink (SUL) (1 in this case) when two carriers are used for the uplink of a cell.

[0086] For the purposes described above, the UE receiving the RAR message sends another message (1c-31) on the resources allocated to the RAR message. The third message sent in the example diagram is also referred to as Msg3 (i.e., the preamble in operation 1c-11 or 1c-13 is also referred to as Msg1, and the RAR in operation 1c-21 is referred to as Msg2). As an example of Msg3 sent by the UE, in the case of initial access, it may include an RRCSetupRequest message as an RRC layer message; in the case of reconnection, it may include an RRCReestablishmentRequest message; and in the case of handover, it may include an RRCReconfigurationComplete message, but the invention is not limited thereto. Alternatively, a Buffer Status Report (BSR) message for resource requests may be sent as Msg3.

[0087] Subsequently, for the initial transmission (i.e., Msg3 does not include the BS identifier information previously assigned to the UE, etc.), the UE can receive a contention resolution message (1c-41) from the BS. The contention resolution message includes the content sent by the UE in Msg3 as is, and may indicate which UE is responding even if multiple UEs have selected the same preamble in operation 1c-11 or 1c-13.

[0088] Figure 1DThis is a diagram illustrating a two-step random access procedure performed by a UE for a gNB according to an embodiment of this disclosure.

[0089] As referenced above Figure 1C In the case of performing a typical contention-based random access procedure, at least four steps can be performed, and if an error occurs in one step, the procedure can be further delayed. Therefore, scenarios that reduce the random access process to a two-step procedure can be considered.

[0090] Therefore, MsgA is sent (1d-15), followed by four consecutive preambles for the random access procedure: Msg1 1d-11 (corresponding to 1c-11) and Msg3 1d-13 (corresponding to 1c-31). Subsequently, the gNB that has received MsgA sends MsgB 1d-19, which includes information about the four-step random access procedure: Msg2 (RAR) (corresponding to 1c-21) and Msg4 (corresponding to 1c-41), thus potentially reducing the number of random access steps. This procedure... Figure 1D Description (1d-00).

[0091] Here, when MsgA is represented by time, MsgA can be the corresponding transmission of Msg1 and Msg3. For example, MsgA can be transmitted on PRACH resource 1d-21 for transmitting Msg1, PUSCH resource 1d-23 for transmitting Msg3, and gap resource 1d-22 for resolving interference issues that may occur during transmission on PUSCH resources. Furthermore, since Msg3 includes information associated with Msg1, the gNB can identify which UE transmitted Msg3 by recognizing the preamble (Msg1) transmitted by the UE. Alternatively, there can be multiple PUSCH resources corresponding to PRACH resources; therefore, a rule can exist to map the PUSCH resources to be used in the transmission of Msg3 based on the preamble index transmitted on the PRACH resources, such that the gNB can identify which UE transmitted Msg3 by recognizing the preamble (Msg1) transmitted by the UE.

[0092] As mentioned above Figure 1CAs described, a UE can perform random access for various purposes. For example, a UE not yet connected to a gNB can perform random access to send a connection message, or a UE previously connected but not disconnected due to an error can perform random access to send a re-establishment message, and this message can be a message belonging to the Common Control Channel (CCCH). Control messages belonging to the CCCH may include RRCSetupRequest (when transitioning from idle mode (RRC_IDLE) to connected mode), RRCResumeRequest (when transitioning from inactive mode (RRC_INACTIVE) to connected mode), RRCReestablishmentRequest (when re-establishing a connection), and RRCSystemInfoRequest (when requesting system information broadcast by the BS), but the invention is not limited to the above examples. Therefore, when a UE performs two-step random access, the UE can send the MsgA by including the message in the MsgA. If the UE accesses the gNB and then performs random access in a connected state, the UE can notify the entity performing the random access that it is the UE by sending a C-RNTIMAC CE including the UE's identifier information in the MsgA.

[0093] A gNB that has received both Msg1 and Msg3 included in MsgA can send MsgB to the UE (1d-19). Here, MsgB may include the aforementioned BI. Furthermore, when MsgA includes the aforementioned CCCH message, it may include the UL transmission timing information (Timing Advance Command (TAC)) sent in Msg2, the UE temporary identifier (temporary C-RNTI) to be used by the gNB later, and the UE contention resolution identifier sent in Msg4. Additionally, if the UE is already connected to the gNB and sends a C-RNTI MAC CE including UE identifier information in MsgA, the message by which the gNB allocates resources to the UE on the PDCCH via the UE's identifier (C-RNTI) may be MsgB.

[0094] If a conflict occurs due to the transmission of multiple MsgA in operation 1d-15, the gNB can only receive (multiple) Msg1 included in MsgA, but cannot receive Msg3. In this case, the gNB can send Msg2 1d-65 to the UE instead of MsgB1d-19, thus changing to the 4-step random access procedure described with reference to FIG1c and performing the remaining random access procedures. This is in Figure 1DAs described in (1d-50), the mode of switching from 2-step random access to 4-step random access as described above is called the fallback mode. That is, when the gNB receives a message from the UE only on PRACH resources (1d-61) and (1d-21), the gNB sends a response to it via a fallback RAR similar to Msg2 used in the 4-step random access procedure (1d-65), thereby allowing the UE to perform the transmission and reception of Msg3 (1d-71) and Msg4 (1d-73) of the 4-step random access procedure.

[0095] Figure 1E This is a diagram illustrating an example of the DL and UL channel frame structure when beam-based communication is performed in an NR system according to an embodiment of the present disclosure.

[0096] exist Figure 1E In this context, BS1e-01 can transmit signals in beams 1e-11, 1e-13, 1e-15, and 1e-17 for wide coverage or to transmit stronger signals. Therefore, UE 1e-03 in the cell may have to use a specific beam transmitted by the BS ( Figure 1E The beam #1 1e-13 in the middle is used to send and receive data.

[0097] Depending on whether the UE is connected to the BS, the UE's state can be divided into idle mode (RRC_IDLE) and connected mode (RRC_CONNECTED). Therefore, the BS may not know the location of a UE in idle mode.

[0098] If a UE in idle mode attempts to transition to connected mode, the UE can receive synchronization signal blocks (SSBs) 1e-21, 1e-23, 1e-25, and 1e-27 transmitted by the BS. The SSBs can be SSB signals periodically transmitted by the BS at fixed intervals, and each SSB may include a primary synchronization signal (PSS) 1e-41, a secondary synchronization signal (SSS) 1e-43, and a physical broadcast channel (PBCH).

[0099] exist Figure 1E In this context, we assume a scenario where SSBs are transmitted on each beam. For example, we assume that SSB#0 1e-21 is transmitted using beam #0 1e-11, SSB#1 1e-23 is transmitted using beam #1 1e-13, SSB#21e-25 is transmitted using beam #2 1e-15, and SSB#31e-27 is transmitted using beam #3 1e-17. Furthermore, in... Figure 1E In this case, it is assumed that the UE in idle mode is located in beam #1, but even if the UE in connected mode performs random access, the UE will select the SSB received when the UE performs random access.

[0100] Reference Figure 1E The UE can receive SSB#1 transmitted on beam #1. Upon receiving SSB#1, the UE obtains the BS's Physical Cell Identifier (PCI) via the PSS and SSS. Since the UE receives the PBCH, it can identify the identifier of the currently received SSB (i.e., #1), the location within a 10ms frame where the current SSB was received, and in which System Frame Number (SFN) with a period of 10.24 seconds was the current SSB received. Furthermore, the Master Information Block (MIB) can be included in the PBCH and can include information about the location where System Information Block Type 1 (SIB1) broadcasting more detailed cell configuration information is receptive. Upon receiving SIB1, the UE can know the total number of SSBs transmitted by the BS and can identify the location of Physical Random Access Channel (PRACH) timings 1e-30 to 1e-39, during which the UE can perform random access to transition to connected mode (more specifically, be able to transmit a preamble as a physical signal specifically designed for UL synchronization). Figure 1E In this scenario, we assume that an SSB is allocated every 1ms.

[0101] Furthermore, the UE can determine which PRACH timing corresponds to which SSB index based on SIB1 information. For example, in Figure 1E In this scenario, we assume an SSB is allocated every 1 ms, and that each PRACH timing allocates 1 / 2 SSB (i.e., two PRACH timings per SSB). Therefore, we show a scenario where two PRACH timings are allocated to each SSB starting from the PRACH timings based on the SFN value. Specifically, PRACH timings 1e-30 and 1e-31 can be allocated to SSB#0, and PRACH timings 1e-32 and 1e-33 can be allocated to SSB#1. After all SSBs have been configured, PRACH timings (PRACH timings 1e-38 and 1e-39) can be reassigned to the first SSB.

[0102] Therefore, the UE can identify the positions of PRACH timings 1e-32 and 1e-33 of SSB#1, and can transmit the random access preamble in the earliest PRACH timing (e.g., PRACH timing 1e-32) of the current time between PRACH timings 1e-32 and 1e-33 corresponding to SSB#1. Since the BS has already received the preamble in PRACH timing 1e-32, the BS can know that the UE has selected SSB#1 and transmitted the preamble, and can transmit and receive data on the beam corresponding to SSB#1 when performing random access subsequently.

[0103] When a UE in a connected state moves from a source BS to a target BS due to handover, the UE can perform random access to the target BS and can perform operations such as selecting an SSB and sending random access commands. Furthermore, during handover, a handover command is sent to the UE to move from the source BS to the target BS, and in this case, a dedicated random access preamble identifier is assigned to the handover command message for each SSB of the target BS for use when performing random access to the target BS. Here, the BS may not assign dedicated random access preamble identifiers for all beams (depending on the UE's current location, etc.), and therefore, dedicated random access preambles may not be assigned to some SSBs (e.g., dedicated random access preambles are only assigned to Beam#2 and Beam#3).

[0104] When a dedicated random access preamble is not assigned to the SSB selected by the UE for preamble transmission, the UE randomly selects a contention-based random access preamble and can subsequently perform random access. For example, in this diagram, after the UE initially attempts random access in Beam #1 but fails, the following scenario is possible: where the UE is in Beam #3 and transmits the dedicated preamble when it retransmits the random access preamble. That is, even if a preamble retransmission occurs during a random access procedure, contention-based and contention-free random access procedures can coexist, depending on whether the dedicated random access preamble is assigned to the selected SSB for each preamble transmission.

[0105] Furthermore, even if no handover is performed as described above, if the UE suddenly moves within a BS, the UE may exit the beam currently used for data transmission and reception, and if the BS cannot detect it and fails to change the beam, the UE can detect a beam failure. This is called beam failure detection (BFD).

[0106] For example, the BS can configure a connected UE to detect beam faults for the SSBs corresponding to beams #1 1e-13 and #2 1e-15 via RRC layer messages. However, when the UE suddenly moves to beam #3 1e-17, neither beams #1 1e-13 nor #2 1e-15 are detected. Therefore, the UE's physical layer sends a beam fault instance indication to the UE's MAC layer. When the MAC layer receives the beam fault instance indication, it can start a beam fault detection timer (or restart the timer if it is already running) and increment a counter (BFI_COUNTER). If the counter value reaches (i.e., is equal to or greater than) the threshold (beamFailureInstanceMaxCount) configured by the RRC layer messages, the UE determines that a beam fault has occurred and then executes procedures for beam fault recovery.

[0107] Beam failure can occur in either the SpCell or the SCell. For example, a beam failure may occur in the SCell when the SpCell uses low frequencies with almost no beam and the SCell uses high frequencies with narrow beamwidths. However, the invention is not limited to the above examples.

[0108] According to embodiments of this disclosure, when using DC technology that uses two BSs (MCG and SCG) simultaneously, SpCell can instruct a cell including the PCell of the MCG (to which the UE performs initial access or reconstruction procedures) and the PSCell of the SCG (to which random access is performed during SCG addition and modification procedures (using synchronous reconfiguration)).

[0109] If a beam failure occurs in a SCell, the UE can notify which SCell the beam failure occurred in by sending a MAC CE, which is a control message of the MAC layer. More specifically, the MAC CE may include additional information indicating which SCell the beam failure occurred in and which beam in the SCell to use. To send the MAC CE, the UE may request UL resources from the BS. A MAC CE used for this purpose is called a Beam Failure Recovery (BFR) MAC CE or a SCell BFR MAC CE.

[0110] In LTE and NR, conventional UL resource requests are performed via a transmit buffer status report (BSR) MAC CE. In the case of a conventional BSR, which is one of the conditions for triggering BSR transmission, the UE triggers a scheduling request (SR) to send 1 bit of information about PUCCH resources to the BS, where the PUCCH resources are allocated for an SR previously allocated by the RRC layer, so that the BS can allocate UL for the transmission of the BSR.

[0111] However, in order to request the transmission of a BFR MAC CE, the UE can send a 1-bit information to the BS regarding PUCCH resources, which are allocated for an SR previously allocated by the RRC layer, allowing the BS to allocate a UL for the transmission of the BFR MAC CE. When the UE receives the UL after sending the SR, the UE can send a BFR MAC CE, as described below, to notify the BS of the necessity of a BFR for the corresponding SCell.

[0112] When a beam failure occurs in the SpCell, the UE can recover the beam through a random access procedure. For example, the BS can assign a dedicated random access preamble to the UE for each beam to prepare for a beam failure. For instance, the BS can configure a dedicated preamble identifier for beam #3 in the diagram, and when the UE selects beam #3 while performing random access after detecting a beam failure, the UE can notify the BS that it has selected beam #3 after detecting a beam failure by sending the dedicated preamble identifier configured by the BS, so that the BS can adjust the beam for the UE. Alternatively, even when the BS has not assigned a dedicated random access preamble, the UE can perform contention-based random access, thereby notifying the BS of the beam currently selected for random access. Furthermore, the UE can include and send a separate additional message to notify the BS that it has performed random access due to BFR. The separate additional message includes references to the following... Figure 1F The content described.

[0113] Figure 1F This is a diagram illustrating an example of a message that the UE will send to the BS when performing a BFR on the SpCell according to an embodiment of this disclosure.

[0114] Figure 1F MAC CE 1f-01 and MAC CE 1f-21 can be used for SCellBFR MAC CE. The UE can use either the format according to 1f-01 or the format according to 1f-21, depending on the maximum value in the SCell identifier (or serving cell identifier) ​​within the corresponding cell group (MCG or SCG).

[0115] Reference Figure 1FEach C field can indicate from which serving cell the beam fault was detected, and one or more bytes of information including the subsequent eight bytes 1f-07 or 1f-27 of the AC field 1f-05 or 1f-25 (i.e., a byte configured with AC / R / candidate RS ID or R bits) can report details of the cell indicated as 1 in each C field.

[0116] For example, when all three items in the C field are configured to 1, 3 bytes of additional information corresponding to the C field configured to 1 can be sent after the bitmap of the C field. Here, the AC field 1f-05 or 1f-25 can indicate whether there is beam information (candidate RS ID) available for additional beam recovery, and if the AC field 1f-05 or 1f-25 is configured to 1, it indicates the candidate RS ID, and if configured to 0, the AC field can be filled with all R (reserved) bits. That is, the UE can report information about each of the cells indicated as 1 in the C field.

[0117] Furthermore, in MAC CE 1f-01 and MAC CE 1f-21, to report not only SCell but also SpCell, the C0 field 1f-03 or 1f-23 can be used to notify of a detected beam fault for the SpCell. That is, the traditional C field is used based on the SCell identifier (or serving cell identifier), for example, the C5 field is used when there is a problem with SCell #5. However, in this invention, when reporting a message in the MCG, the C0 field 1f-03 or 1f-23 is associated with the PCell, while when reporting a message in the SCG, the C0 field 1f-03 or 1f-23 is associated with the PSCell. The serving cell identifier of the PCell is 0, but even when the serving cell identifier of the PSCell is a different value other than 0, there is no serving cell using #0 in the SCG; therefore, the PSCell can use the C0 field 1f-03 or 1f-23. Therefore, the UE configures the C0 field 1f-03 or 1f-23 to 1, thereby indicating to the BS that a beam fault for SpCell has been detected.

[0118] When in Figure 1FWhen the C0 field 1f-03 or 1f-23 is configured to 1, the UE may not include the octet 1f-07 or 1f-27 containing AC 1f-05 or 1f-25 for the SpCell in the MAC CE. This is because, during the random access procedure, the BS can infer information about the current beam based on the preamble index and position sent by the UE. Alternatively, to maximize the reuse of existing formats, the MAC CE may include the octet 1f-07 or 1f-27 containing AC 1f-05 or 1f-25 not only for the SCell but also for the SpCell, and may always include the R bit instead of the candidate RS ID. Alternatively, the MAC CE may include the octet 1f-07 or 1f-27 containing AC 1f-05 or 1f-25 not only for the SCell but also for the SpCell, and when there is reference signal (CSI-RS) information measured by the UE for the SpCell, the MAC CE may include and transmit this information.

[0119] The BFR MAC CE for SpCell in the second embodiment is a different format from the existing BFR MAC CE for SCell. Here, one suggestion is to use a MAC CE without a payload. The MAC subheader 1f-51 is added to the data including the MAC CE and sent / received by the MAC layer, and in the transmission of data / MAC CEs with variable lengths, first and second formats including the L field are used depending on the length of the data / MAC CE (the first format is used when the F field is 0, and the second format is used when it is 1). Furthermore, when the MAC CE has a configured length, a third format including only the LCID without the L field can be used.

[0120] If one of the LCID values ​​is used for BFR MAC CE against SpCell, a format including only the third MAC subheader can be sent. Alternatively, as Figure 1F As shown in MAC CE 1f-31, a format of only eight bytes can be defined that does not include the C field and includes the AC for SpCell. In this case, since MAC CE 1f-31 without the C field is sent in the third MAC subheader of 1f-51, the actual size sent can be 2 bytes.

[0121] However, this disclosure is not limited to this example, and as a BFR MAC CE, a MAC CE can be sent that does not include the first and second MAC subheaders and the C field for sending data of variable length and includes a format for sending only eight-bit bytes of AC for SpCell. Furthermore, all combinations of the two MAC CEs 1f-01 and 1f-21 from the first embodiment described above, as well as the three types of MAC subheader 1f-51, can be used.

[0122] In the third embodiment, no new MAC CE for BFR is introduced. In the current embodiment, when a UE in a connected state performs random access, the UE sends a C-RNTI MAC CE 1f-41 to inform the UE of its identity, and according to the prior art, the UE indicates the C-RNTI MAC CE by inserting the value 58 into the LCID field of the MAC subheader. However, in the current embodiment, another value, along with the value 58, is additionally assigned to the UE to notify that the current MAC CE is a C-RNTI MAC CE and that the UE performs random access for BFR against the SpCell. That is, compared to the second embodiment where the MAC CE does not have a payload, one byte can be further saved.

[0123] When a UE transmits data in the UL, the BS does not allocate UL resources for specific data of the UE. Instead, it allocates available resources for all data currently in the buffer. Here, the UE does not randomly fill the allocated resources, but transmits data on the allocated resources according to the priority order and filling method defined by the rules. This is called Logical Channel Priority (LCP). In the current NR rules, the priority order for MAC CE and data is configured as follows.

[0124] -C-RNTI MAC CE or data from UL-CCCH;

[0125] -Configured Authentication and Authorization Code (CGC) MAC CE;

[0126] - MAC CE of BSR, except for the BSR used for filling;

[0127] - Single PHR MAC CE or multiple PHR MAC CE;

[0128] - Data from any logical channel, except for data from UL-CCCH;

[0129] - MAC CE used for recommending bit rate queries;

[0130] - Includes MAC CE for filling BSR.

[0131] Here, the MAC CE used in the BFR report for SCell has a very high priority to maintain the connection, and the MAC CE can have the same priority as the CGC MAC CE. However, the invention is not limited thereto.

[0132] In the first embodiment, when the BFR MAC CE for SCell is also used for SpCell among the various BFR MAC CE formats for SpCell described above, if the BFR information for SpCell is included in the BFR MAC CE, then the BFR MAC CE can be configured to have a higher priority than the CGC MAC CE. This is because connection recovery for SpCell has a very high priority. Furthermore, in the second and third embodiments, when the format of the BFR MAC CE for SpCell is different from the format of the BFR MAC CE for SCell, the BFR MAC CE for SpCell can be configured to have a higher priority than the BFR MAC CE.

[0133] Figure 1G This is a diagram illustrating a first example of UE operation when the UE performs beam fault detection and recovery against SpCell according to an embodiment of the present disclosure.

[0134] exist Figure 1G In this scenario, assuming the UE is connected to the BS and is therefore in connected mode (RRC_CONNECTED) (Operation 1g-01), the BS configures the UE with configuration information associated with the aforementioned beam fault detection and recovery, and sends a corresponding acknowledgment message (Operation 1g-03). The configuration information sent by the BS can be received using the RRCReconfiguration message at the RRC layer, and the acknowledgment message sent by the UE can be sent using the RRCReconfigurationComplete message at the RRC layer. The configuration information received from the BS may include configuration information that allows the UE to report beam faults when it determines a beam fault for SpCell and SCell.

[0135] When the UE receives the configuration information, it determines that a beam fault has occurred for SpCell and SCell, as described above (Operation 1g-05). The UE can determine the beam fault for each serving cell based on the beam fault detection timer and counter described above.

[0136] The UE can detect beam faults for SpCell or SCell (Operation 1g-07).

[0137] If a beam fault is detected for a SCell, the UE determines whether it has UL resources for transmitting a BFR MAC CE according to the current LCP operation (Operation 1g-21). If the UE has UL resources for transmitting a BFR MAC CE, the UE may instruct a multiplexing and assembling entity configured to generate data to include the BFR MAC CE for the SCell in the available resources to transmit data on the corresponding resources (Operation 1g-25). If the UE does not have UL resources for transmitting a BFR MAC CE, the UE may determine whether a PUCCH SR resource for transmitting the SCell BFR MAC CE has been allocated by a message from the RRC layer, and if no separate SR resource has been allocated, the UE performs a random access procedure by sending a random access Msg3 message to the BS by adding the SCell BFR MAC CE to the Msg3 message, and thus notifying the UE of a beam fault for the specific SCell. If the BS configures PUCCH SR resources for transmitting SCell BFR MAC CE, the UE transmits the corresponding SR, and then transmits the SCell BFR MAC CE on the UL resources received from the BS (Operation 1g-23). ​​Subsequently, when the BS allocates UL resources for new data transmission for the HARQ process used to transmit the transmitted SCell BFR MAC CE, the UE determines that the BFR MAC CE transmitted along with the corresponding HARQ process ID was successfully transmitted, and therefore determines that the BFR was successfully executed.

[0138] If a beam fault is detected for SpCell, the UE triggers random access for the BFR in SpCell (Operation 1g-11). If the UE supports 2-step random access and the BS has configured resources for 2-step random access, the UE performs 2-step random access when the DL link signal strength is greater than a preset threshold configured by the BS; otherwise, the UE determines to perform 4-step random access (Operation 1g-13). If the UE determines to perform 2-step random access (Operation 1g-15), and if the random access is for the BFR for SpCell, the UE instructs the multiplexing and assembly entity to include the BFR MAC CE for SpCell in the initial transmission of MsgA (Operation 1g-17). Furthermore, if the UE determines to perform a 4-step random access (Operation 1g-15), and if the random access is for BFR for SpCell, or if the UE selects a contention-based preamble, when the UE receives the RAR after the preamble transmission (i.e., when resources for UL transmission are allocated in the RAR), the UE instructs the multiplexing and assembly entity to include a BFR MAC CE for SpCell (Operation 1g-19). Therefore, the UE can send the corresponding MAC CE to the BS during random access, thereby notifying the BS that random access for BFR has been performed.

[0139] Figure 1H This is a diagram illustrating a second example of UE operation when the UE performs beam fault detection and recovery against SpCell according to an embodiment of the present disclosure.

[0140] exist Figure 1H In this scenario, assuming the UE is connected to the BS and is therefore in connected mode (RRC_CONNECTED) (Operation 1h-01), the BS configures the UE with configuration information associated with the aforementioned beam fault detection and recovery, and sends a corresponding acknowledgment message (Operation 1h-03). The configuration information sent by the BS can be received via the RRCReconfiguration message using the RRC layer, and the acknowledgment message sent by the UE can be sent via the RRCReconfigurationComplete message using the RRC layer. The configuration information received from the BS may include configuration information that allows the UE to report beam faults when it determines a beam fault for SpCell and SCell.

[0141] When the UE receives the configuration information, it determines that a beam fault has occurred for SpCell and SCell, as described above (Operation 1h-05). The UE can determine the beam fault for each serving cell based on the beam fault detection timer and counter mentioned above.

[0142] The UE can detect beam faults for SpCell or SCell (Operation 1h-07).

[0143] If a beam fault is detected for a specific SCell, the UE determines whether it has UL resources for transmitting a BFR MAC CE according to the current LCP operation (Operation 1h-21). If the UE has UL resources for transmitting a BFR MAC CE, the UE can instruct the multiplexing and assembling entity configured to generate data to include the BFR MAC CE for the SCell in the available resources to transmit data on the corresponding resources (Operation 1h-25). If the UE does not have UL resources for transmitting a BFR MAC CE, the UE can determine whether a PUCCH SR resource for transmitting the SCell BFR MAC CE has been allocated by the RRC layer. If no separate SR resource has been allocated, the UE performs a random access procedure by sending a random access Msg3 message to the BS by adding the SCell BFR MAC CE to the Msg3 message, and thus notifies the UE of a beam fault for the specific SCell. If the BS configures PUCCH SR resources for transmitting SCell BFR MAC CE, the UE transmits the corresponding SR, and then transmits the SCell BFR MAC CE on the UL resources received from the BS (operation 1h-23). ​​Subsequently, when the BS allocates UL resources for new data transmission for the HARQ process used to transmit the transmitted SCell BFR MAC CE, the UE determines that the BFR MAC CE transmitted along with the corresponding HARQ process ID was successfully transmitted, and therefore determines that the BFR was successfully executed.

[0144] If a beam fault is detected for the SpCell, the UE triggers random access for BFR in the SpCell (Operation 1h-11). Furthermore, the UE instructs the multiplexing and assembly entity to include the BFR MAC CE for the SpCell (Operation 1h-13). That is, the BFR MAC CE can be transmitted on UL resources allocated during random access, or on UL resources if the BS has previously allocated UL resources. Therefore, when the BFR MAC CE is transmitted on resources other than those received from the RAR and is determined to have been successfully received, the UE can determine that the BFR operation has been successfully performed and can therefore prematurely stop the triggered random access (Operation 1h-17). As a method performed by the UE to determine the successful reception of the BFR MAC CE, when the BS allocates UL resources for new data transmission for the HARQ process of transmitting the BFR MAC CE for the SpCell, the UE determines that the BFR MAC CE transmitted with the corresponding HARQ process ID has been successfully transmitted, thus determining that the BFR has been successfully performed. If a BFR MAC CE is sent during the random access operation, the UE will also determine that the BFR was successfully executed when the random access is successfully executed (Operation 1h-19). According to the random access procedure, the UE can send a BFR MAC CE for the SpCell to notify the UE that random access has been executed due to the BFR.

[0145] According to embodiments of this disclosure, the BS can be operated in accordance with reference to... Figure 1G to 1H The UE operations described are as follows. For example, the BS can send BFD and BFR associated configurations to the UE. Furthermore, the BS can receive BFR MAC CE and configure PUCCH SR resources for BFR MAC CE transmission. Additionally, the BS can receive SRs and allocate UL resources for BFR MAC CE transmission. Furthermore, the BS can allocate UL resources for new data transmission for the HARQ process used for BFR MAC CE transmission. In other words, the BS can operate in a manner corresponding to UE operations performing beam fault detection and recovery.

[0146] Figure 1I This is a block diagram illustrating the construction of a UE according to an embodiment of the present disclosure.

[0147] Reference Figure 1I The UE may include a radio frequency (RF) processor 1i-10, a baseband processor 1i-20, a storage device 1i-30, and a controller 1i-40. However, this disclosure is not limited to this example, and the UE may include more than [example of controller]. Figure 1I The configurations shown are fewer or more configurations.

[0148] The RF processor 1i-10 performs functions such as transmitting and receiving signals via a wireless channel, including signal band conversion and amplification. Specifically, the RF processor 1i-10 up-converts the baseband signal provided by the baseband processor 1i-20 into an RF band signal, then transmits the RF band signal through an antenna, and down-converts the RF band signal received through the antenna back into a baseband signal. For example, the RF processor 1i-10 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a digital-to-analog converter (DAC), an analog-to-digital converter (ADC), etc. Although... Figure 1I Only one antenna is shown, but the UE may include multiple antennas. Furthermore, the RF processor 1i-10 may include multiple RF chains. Additionally, the RF processor 1i-10 can perform beamforming. For beamforming, the RF processor 1i-10 can adjust the phase and intensity of corresponding signals transmitted or received through multiple antennas or antenna elements.

[0149] The baseband processor 1i-20 performs the conversion between baseband signals and bit strings based on the system's physical layer specifications. For example, for data transmission, the baseband processor 1i-20 generates composite symbols by encoding and modulating the transmitted bit string. For data reception, the baseband processor 1i-20 reconstructs the received bit string by demodulating and decoding the baseband signal provided from the RF processor 1i-10. For example, according to the OFDM scheme, for data transmission, the baseband processor 1i-20 generates composite symbols by encoding and modulating the transmitted bit string, maps the composite symbols to subcarriers, and then configures the OFDM symbols by performing an inverse fast Fourier transform (IFFT) and inserting a cyclic prefix (CP). For data reception, the baseband processor 1i-20 can segment the baseband signal provided from the RF processor 1i-10 into OFDM symbol units, reconstruct the signal mapped to the subcarriers by performing a fast Fourier transform (FFT) calculation, and then reconstruct the received bit string by demodulating and decoding the signal.

[0150] The baseband processor 1i-20 and the RF processor 1i-10 transmit and receive signals in the manner described above. Therefore, the baseband processor 1i-20 and the RF processor 1i-10 can also be referred to as transmitters, receivers, transceivers, or communicators. At least one of the baseband processor 1i-20 and the RF processor 1i-10 may include different communication modules to process signals in different frequency bands. These different frequency bands may include ultra-high frequency (SHF) bands (e.g., 2.5 GHz or 5 GHz) and millimeter wave (mmWave) bands (e.g., 60 GHz). The UE can transmit and receive signals to and from the BS using the baseband processor 1i-20 and the RF processor 1i-10, and these signals may include control information and data.

[0151] Storage device 1i-30 can store basic programs, application programs, and data for UE operation, such as configuration information. Storage device 1i-30 may include any or a combination of storage media such as read-only memory (ROM), random access memory (RAM), hard disk, CD-ROM, and DVD. Furthermore, storage device 1i-30 may include multiple memories. According to embodiments of this disclosure, storage device 1i-30 can store programs for a method by which a UE performing beam fault detection and recovery for SpCell according to this disclosure is performed.

[0152] Controller 1i-40 controls the overall operation of the UE. For example, controller 1i-40 transmits and receives signals via baseband processor 1i-20 and RF processor 1i-10. Furthermore, controller 1i-40 records and reads data on or from storage device 1i-40. For this purpose, controller 1i-40 may include at least one processor. For example, controller 1i-40 may include a communication processor (CP) for communication control and an application processor (AP) for controlling upper layers such as applications. Furthermore, at least one configuration in the UE can be implemented as a single chip. According to embodiments of the invention, controller 1i-40 may include a multi-connection processor 1i-42 to perform processing for operations in a multi-connection mode. For example, controller 1i-40 may control the UE to perform... Figure 1I The procedure for UE operation is shown.

[0153] According to embodiments of this disclosure, the UE can receive configuration associated with the transmission of BFR MAC CE from the BS, and can generate and transmit BFR MAC CE messages.

[0154] Figure 1J This is a block diagram illustrating the construction of a BS according to an embodiment of the present disclosure.

[0155] Reference Figure 1J The BS may include an RF processor 1j-10, a baseband processor 1j-20, a communicator 1j-30, a storage device 1j-40, and a controller 1j-50. However, this disclosure is not limited to this example, and the BS may include more than [example of such a device]. Figure 1J The configurations shown are fewer or more configurations.

[0156] RF processor 1j-10 performs functions such as transmitting and receiving signals via a wireless channel, including signal band conversion and amplification. Specifically, RF processor 1j-10 up-converts the baseband signal provided by baseband processor 1j-20 into an RF band signal, then transmits the RF band signal through an antenna, and down-converts the RF band signal received through the antenna back into a baseband signal. For example, RF processor 1j-10 may include a transmit filter, receive filter, amplifier, mixer, oscillator, DAC, ADC, etc. Although... Figure 1J Only one antenna is shown, but the RF processor 1j-10 may include multiple antennas. Furthermore, the RF processor 1j-10 may include multiple RF chains. Additionally, the RF processor 1j-10 can perform beamforming. For beamforming, the RF processor 1j-10 can adjust the phase and intensity of corresponding signals transmitted or received through multiple antennas or antenna elements. The RF processor 1j-10 can perform DL MIMO operation by transmitting one or more layers.

[0157] The baseband processor 1j-20 can convert between baseband signals and bit strings according to the physical layer specifications of a preset radio access technology. For example, for data transmission, the baseband processor 1j-20 can generate composite symbols by encoding and modulating the transmitted bit string. For data reception, the baseband processor 1j-20 can reconstruct the received bit string by demodulating and decoding the baseband signal provided from the RF processor 1j-10. For example, according to the OFDM scheme, for data transmission, the baseband processor 1j-20 can generate composite symbols by encoding and modulating the transmitted bit string, map the composite symbols to subcarriers, and then configure the OFDM symbols by performing IFFT and inserting a cyclic prefix (CP). For data reception, the baseband processor 1j-20 can segment the baseband signal provided from the RF processor 1j-10 into OFDM symbol units, reconstruct the signal mapped to the subcarriers by performing FFT calculations, and then reconstruct the received bit string by demodulating and decoding the signal. The baseband processor 1j-20 and the RF processor 1j-10 can transmit and receive signals in the above manner. Therefore, the baseband processor 1j-20 and the RF processor 1j-10 can also be referred to as transmitters, receivers, transceivers, or communicators. The BS can send signals to and receive signals from the UE using the baseband processor 1j-20 and the RF processor 1j-10, and these signals can include control information and data.

[0158] Communicator 1j-30 provides an interface for communicating with other nodes in the network. Specifically, communicator 1j-30 converts bit strings into physical signals, which are sent from the primary BS to another node, such as a secondary BS or the core network, and converts physical signals back into bit strings, which are received from other nodes. Communicator 1j-30 may include a backhaul communicator.

[0159] Storage device 1j-40 stores basic programs, application programs, and data for BS operation, such as configuration information. Storage device 1j-40 may store information about bearers assigned to access UEs, measurement results reported from access UEs, etc. Furthermore, storage device 1j-40 may store information as a reference for whether to provide or terminate multiple connections to the UE. Storage device 1j-40 provides the stored data in response to requests from controller 1j-50. Storage device 1j-40 may include any storage medium or combination thereof, such as ROM, RAM, hard disk, CD-ROM, and DVD. Furthermore, storage device 1j-40 may include multiple memories. According to some embodiments, storage device 1j-40 may store programs for a method by which beam fault detection and recovery against SpCell is performed according to the BS of this disclosure.

[0160] Controller 1j-50 controls the overall operation of the BS. For example, controller 1j-50 transmits and receives signals via baseband processor 1j-20 and RF processor 1j-10 or communicator 1j-30. Furthermore, controller 1j-50 records and reads data on or from storage device 1j-40. For this purpose, controller 1j-50 may include at least one processor. According to an embodiment of the invention, controller 1j-50 includes a multi-connection processor 1j-52 to perform processing for operation in a multi-connection mode.

[0161] Furthermore, at least one configuration of the BS can be implemented as a chip. Additionally, each configuration of the BS can operate to perform the foregoing embodiments of this disclosure.

[0162] The methods according to embodiments of the present invention described in the claims or specification can be implemented as hardware, software, or a combination of hardware and software.

[0163] When implemented as software, a computer-readable storage medium may be provided for storing one or more programs (e.g., software modules). The one or more programs stored in the computer-readable storage medium may be configured to be configured by one or more processors within an electronic device. The one or more programs include instructions instructing the electronic device to perform methods according to embodiments of this disclosure as described in the claims or specification.

[0164] The program (e.g., a software module or software) can be stored in non-volatile memory, including RAM or flash memory, ROM, electrically erasable programmable read-only memory (EEPROM), disk storage devices, CD-ROM, DVD, another optical storage device, or magnetic tape. Alternatively, the program can be stored in a memory comprising some or all of the above-described storage media. Multiple such memories may be included.

[0165] Furthermore, the program can be stored in an attachable storage device accessible via any network or combination of networks such as the Internet, intranet, local area network (LAN), wide area network (WLAN), and storage area network (SAN). Such storage devices can be connected to a device executing embodiments of this disclosure via an external port. Additionally, a separate storage device on the communication network can be connected to an electronic device executing embodiments of this disclosure.

[0166] In the above embodiments of this disclosure, elements included in this disclosure are represented in singular or plural form according to embodiments of this disclosure. However, for ease of description, singular or plural forms are suitably chosen, and this disclosure is not limited thereto. Thus, elements expressed in plural form can also be configured as a single element, and elements expressed in singular form can also be configured as multiple elements.

[0167] Specific embodiments of the invention are described in this specification; however, it should be understood that various modifications can be made without departing from the scope of this disclosure. Therefore, the scope of this disclosure is not limited to the embodiments described herein, but should be defined by the appended claims and their equivalents. In other words, other modifications based on the technical concept of this disclosure will be readily apparent to those skilled in the art. Furthermore, the various embodiments can be combined when necessary. For example, some methods provided by this invention can be combined with each other to enable the BS and UE to operate. Moreover, although embodiments are described based on 5G and NR systems, modifications based on the technical scope of the embodiments can be applied to other communication systems such as LTE, LTE-A, and LTE-A-Pro systems.

Claims

1. A method for beam fault detection and recovery performed by a user equipment (UE), the method comprising: Receive configuration information about beam fault detection and recovery from the base station; Based on the configuration information, beam faults are detected for specific SpCells or SCells, where SpCell is the primary PCell of the primary cell group (MCG) or the primary / secondary PSCell of the secondary cell group (SCG); and Based on the detection results, the beam fault recovery BFR media access control MAC control element CE (BFR MAC CE) is transmitted via a random access procedure. The BFR MAC CE includes a first field. Wherein, in the case that the BFR MAC CE is transmitted in the MCG, the first field indicates the detection of beam fault for the PCell, and In the case where the BFR MAC CE is transmitted in the SCG, the first field indicates the detection of a beam fault for the PSCell.

2. The method according to claim 1, wherein, Also includes: In the event of a beam fault detected for the SCell, determine whether there is an uplink UL resource for transmitting the BFR MACCE; as well as If the UL resource exists, the BFR MAC CE is sent on the UL resource.

3. The method according to claim 2, wherein, Sending the BFR MAC CE on the UL resource includes instructing the reuse and assembly of entities to generate the BFR MAC CE.

4. The method according to claim 1, wherein, Sending the BFR MAC CE includes: Upon detection of a beam fault targeting the SpCell, the random access procedure is triggered; and The BFR MAC CE is sent via the random access procedure.

5. The method according to claim 4, wherein, Sending the BFR MAC CE via the random access procedure includes: In the case that the random access procedure is a two-step random access procedure, the multiplexing and assembly entity is instructed to include the BFRMAC CE in the MSG A, and to transmit the BFRMAC CE via the MSG A.

6. The method according to claim 4, wherein, Sending the BFR MAC CE via the random access procedure includes: In the case that the random access procedure is a 4-step random access procedure, the multiplexing and assembly entity is instructed to include the BFRMAC CE in Msg 3, and to transmit the BFR MAC CE via Msg 3.

7. The method according to claim 1, wherein, The BFR MAC CE also includes an available candidate AC field, which indicates whether information about the candidate reference signal RS ID is included.

8. The method according to claim 1, wherein, When the first field indicates the detection of a beam fault for the SpCell, the BFR MAC CE does not include an eight-bit byte containing the available candidate AC field.

9. A user equipment (UE) for performing beam fault detection and recovery, the UE comprising: transceiver; as well as A processor, coupled to the transceiver, and configured to: Receive configuration information about beam fault detection and recovery from the base station. Based on the configuration information, beam faults are detected related to specific SpCells or SCells, where SpCell is the primary PCell of the primary cell group (MCG) or the primary / secondary PSCell of the secondary cell group (SCG). Based on the detection results, the beam fault recovery BFR media access control MAC control element CE (BFR MAC CE) is transmitted via a random access procedure. The BFR MAC CE includes a first field. Wherein, in the case that the BFR MAC CE is transmitted in the MCG, the first field indicates the detection of beam fault for the PCell, and In the case where the BFR MAC CE is transmitted in the SCG, the first field indicates the detection of a beam fault for the PSCell.

10. The UE according to claim 9, wherein, The processor is also configured to: In the event of a beam fault detected for the SCell, determine whether there are uplink UL resources available for transmitting the BFR MACCE; and If the UL resource exists, the BFR MAC CE is sent on the UL resource.

11. The UE according to claim 9, wherein, The processor is also configured to: Upon detection of a beam fault targeting the SpCell, the random access procedure is triggered, and The BFR MAC CE is sent via the random access procedure.

12. The UE according to claim 11, wherein, The processor is also configured to: In the case that the random access procedure is a two-step random access procedure, the multiplexing and assembly entity is instructed to include the BFRMAC CE in the MSG A, and the BFRMAC CE is transmitted via the MSG A.

13. The UE according to claim 11, wherein, The processor is also configured to: In the case that the random access procedure is a 4-step random access procedure, the multiplexing and assembly entity is instructed to include the BFRMAC CE in Msg 3 and to transmit the BFR MAC CE via Msg 3.

14. The UE according to claim 9, wherein, The BFR MAC CE also includes an available candidate AC field, which indicates whether information about the candidate reference signal RS ID is included.

15. The UE according to claim 9, wherein, In cases where the first field indicates the detection of a beam fault for the SpCell, the BFR MAC CE does not include an eight-bit byte containing the available candidate AC field.

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