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

Abstract

A method performed by a user equipment (UE) in a wireless communication system is provided. The method includes triggering, by a medium access control (MAC) layer, a beam failure recovery for at least one serving cell; identifying, by the MAC layer, whether a candidate beam evaluation for the at least one serving cell for which the beam failure recovery is triggered and not cancelled is completed; generating, by the MAC layer, a MAC control element (CE) for the beam failure recovery based on a result of the identifying, wherein, for the at least one serving cell for which the beam failure is detected and the candidate beam evaluation is completed, a detection information in the MAC CE is set to 1.

Description

TECHNICAL FIELD

[0001] The present application relates generally to a wireless communication system, and more specifically, the present disclosure relates to handling beam failure recovery in a serving cell supporting multiple TRPs. BACKGROUND

[0002] To meet the demand for wireless data traffic having increased since deployment of 4th generation (4G) communication systems, efforts have been made to develop an improved 5th generation (5G) or pre-5G communication system. The 5G or pre-5G communication system is also called a 'beyond 4G network' or a 'post long term evolution (LTE) system'. The 5G communication system is considered to be implemented in higher frequency (mmWave) bands, e.g., 60 GHz bands, so as to accomplish higher data rates. To decrease the propagation loss of radio waves and increase the transmission distance, beamforming, massive multiple-input multiple-output (MIMO), full dimensional MIMO (FD-MIMO), array antennas, and analog beamforming are discussed for use in the 5G communication system. In addition, in the 5G communication system, development for system network improvement is under way based on advanced small cells, cloud radio access networks (RANs), ultra-dense networks, a device-to-device (D2D) communication, wireless backhaul, a moving network, cooperative communication, coordinated multi-points (CoMP), reception-end interference cancellation and the like. In the 5G system, hybrid frequency shift keying (FSK) and Feher's quadrature amplitude modulation (FQAM) and sliding window superposition coding (SWSC) are developed for advanced coding modulation (ACM), and filter bank multi-carrier (FBMC), a non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) are developed for advanced access technology.

[0003] The Internet, which is a human centered connectivity network where humans generate and consume information, is now evolving to the Internet of Things (IoT) where distributed entities, such as things, exchange and process information without human intervention. The Internet of Everything (IoE), which is a combination of the IoT technology and the Big Data processing technology through connection with a cloud server, has emerged as a new paradigm for the IoT. The IoT has been focused on the technical area of the inter-object connection, and the combination of the IoT technology with the existing information technology (IT) or technologies has been approached for the IoT services. As the IoT environment has been combined with the cloud server, the amount of data has been increased, and the techniques of data processing, analysis and utilization have been important. The IoT technology has been combined with 5G technology that has been developed for a high data transfer rate, a high number of connection, a high energy efficiency, a high service reliability, and a low latency. As the combination of the IoT and the 5G, the Internet of Everything (IoE) has been developed. The IoT has been applied to a variety of fields including smart home, smart building, smart city, smart car or connected cars, smart grid, health care, smart appliances, and advanced medical services.

[0004] Accordingly, various attempts have been made to apply the 5G communication system to the IoT network. For example, technologies such as a sensor network, MTC, and M2M communication can be implemented by beamforming, MIMO, and array antennas. Application of a cloud RAN as the above-described big data processing technology can also be considered as an example of convergence between the 5G technology and the IoT technology.

[0005] As described above, various services can be provided according to the development of a wireless communication system, and thus a method for easily providing such services is required. SUMMARY

[0006] [TECHNICAL SOLUTION]

[0007] In one embodiment, a method performed by a user equipment (UE) in a wireless communication system is provided. The method includes triggering, by a medium access control (MAC) layer, beam failure recovery for at least one serving cell; identifying, by the MAC layer, whether candidate beam evaluation for the at least one serving cell for which beam failure recovery is triggered and not cancelled is completed; generating, by the MAC layer, a MAC control element (CE) for the beam failure recovery based on a result of the identification, wherein, for the at least one serving cell for which beam failure is detected and the candidate beam evaluation is completed, detection information in the MAC CE is set to 1. BRIEF DESCRIPTION OF DRAWINGS

[0008] For a more complete understanding of the present disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings in which like reference numerals represent like parts:

[0009] Figure 1 An example of a BFR MAC CE according to an embodiment of the present disclosure is illustrated;

[0010] Figure 2 An example of a BFR MAC CE according to an embodiment of the present disclosure is illustrated;

[0011] Figure 3 An example wireless network according to an embodiment of the present disclosure is illustrated;

[0012] Figure 4 is a flow diagram illustrating beam failure detection and beam failure recovery according to an embodiment of the present disclosure;

[0013] Figure 5 is a flow diagram illustrating beam failure detection and beam failure recovery according to an embodiment of the present disclosure;

[0014] Figure 6 An enhanced format of a BFR MAC CE according to an embodiment of the present disclosure is illustrated;

[0015] Figure 7An enhanced format of a BFR MAC CE according to an embodiment of the disclosure is shown;

[0016] Figure 8 An enhanced format of a BFR MAC CE according to an embodiment of the disclosure is shown;

[0017] Figure 9 An enhanced format of a BFR MAC CE according to an embodiment of the disclosure is shown;

[0018] Figure 10 An enhanced format of a BFR MAC CE according to an embodiment of the disclosure is shown;

[0019] Figure 11 An enhanced format of a BFR MAC CE according to an embodiment of the disclosure is shown;

[0020] Figure 12 An enhanced format of a BFR MAC CE according to an embodiment of the disclosure is shown;

[0021] Figure 13 An enhanced format of a BFR MAC CE according to an embodiment of the disclosure is shown;

[0022] Figure 14 A data transmission / reception method for uplink beam transmission between a terminal and a base station according to an embodiment of the disclosure is shown;

[0023] Figure 15 A data transmission / reception method for uplink beam transmission between a terminal and a base station according to an embodiment of the disclosure is shown;

[0024] Figure 16 A data transmission / reception method for uplink beam transmission between a terminal and a base station according to an embodiment of the disclosure is shown;

[0025] Figure 17 A data transmission / reception method for uplink beam transmission between a terminal and a base station according to an embodiment of the disclosure is shown;

[0026] Figure 18 A data transmission / reception method for uplink beam transmission between a terminal and a base station according to an embodiment of the disclosure is shown;

[0027] Figure 19 A flowchart showing a method performed by a user equipment (UE) in a wireless communication system according to an embodiment of the disclosure is shown;

[0028] Figure 20 is a diagram showing a UE 2000 according to an embodiment of the disclosure; and

[0029] Figure 21 FIG. 1 is a diagram illustrating a base station 2100 according to an embodiment of the disclosure. DETAILED DESCRIPTION

[0030] The disclosure relates to handling beam failure recovery in a serving cell supporting multiple TRPs.

[0031] In one embodiment, a method performed by a user equipment (UE) in a wireless communication system is provided. The method includes triggering, by a medium access control (MAC) layer, beam failure recovery for at least one serving cell; identifying, by the MAC layer, whether candidate beam evaluation for the at least one serving cell for which beam failure recovery is triggered and not cancelled is completed; and generating, by the MAC layer, a MAC control element (CE) for the beam failure recovery based on a result of the identifying, wherein, for the at least one serving cell for which beam failure is detected and candidate beam evaluation is completed, a detection information in the MAC CE is set to 1.

[0032] In another embodiment, a user equipment (UE) in a wireless communication system is provided. The UE includes a transceiver; and at least one processor coupled with the transceiver and configured to: trigger, by a medium access control (MAC) layer, beam failure recovery for at least one serving cell; identify, by the MAC layer, whether candidate beam evaluation for the at least one serving cell for which beam failure recovery is triggered and not cancelled is completed; and generate, by the MAC layer, a MAC control element (CE) for the beam failure recovery based on a result of the identifying, wherein, for the at least one serving cell for which beam failure is detected and candidate beam evaluation is completed, a detection information in the MAC CE is set to 1.

[0033] Other technical features can be readily apparent to one skilled in the art from the following figures, descriptions, and claims.

[0034] INVENTION MODE

[0035] Before undertaking a detailed description of the foregoing, it can be advantageous to set forth definitions of certain terms and phrases used throughout this patent document. The term “coupled” and its derivatives refer to any direct or indirect communication between two or more elements, whether or not those elements are in physical contact with one another. The terms “transmit,” “receive,” and “communicate,” as well as derivatives thereof, encompass both direct and indirect communication. The term “include” and derivatives thereof means inclusion without limitation. The term “or” is inclusive, meaning and / or. The phrase “associated with,” as well as derivatives thereof, means to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, be adjacent to, be interposed with, be bound to or with, have a property of, have relations with, or have dealings with, among others. The term “controller” means any device, system or part thereof that controls at least one operation. Such a controller can be implemented in hardware or a combination of hardware and software and / or firmware. The functionality associated with any particular controller can be centralized or distributed, whether locally or remotely. The phrase “at least one of” followed by a list of two or more items, means that any of the listed items can be employed by itself, or any combination of two or more of the listed items can be employed. For example, “at least one of A, B, and C” means that only A, or only B, or only C, or any combination of the three, can be employed.

[0036] Furthermore, various functions described below can be implemented or supported by one or more computer programs, each of which is formed from computer readable program code and embodied in a computer readable medium. The terms “application” and “program” refer to one or more computer programs, software components, sets of instructions, procedures, functions, objects, classes, instances, related data, or a portion thereof. The phrase “computer readable program code” includes any type of computer code, including source code, object code, and executable code. The phrase “computer readable medium” includes any type of medium capable of being accessed by a computer, such as read only memory (ROM), random access memory (RAM), a hard disk drive, a compact disc (CD), a digital video disc (DVD), or any other type of memory. A “non-transitory” computer readable medium excludes wired, wireless, optical, or other communication links. Non-transitory computer readable media include media that can be permanently stored, as well as media that can store and

[0037] Definitions for other certain words and phrases are provided throughout this patent document. Those of ordinary skill in the art will understand that in many, if not most instances, such definitions apply to prior as well as future uses of such defined words and phrases.

[0038] Before undertaking the detailed description below, it can be advantageous to set forth definitions of certain words and phrases used throughout this patent document: the terms "include" and "comprise," as well as derivatives thereof, mean that following the term, the description can include one or more items, but not the exclusion of other items; the term "or" is inclusive, meaning and / or; the phrases "associated with" and "associated therewith," as well as derivatives thereof, can mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, co, proximate to, be bound to or with, have a property of, have, have a property of, or the like; and the term "controller" means any device, system or part thereof that controls at least one operation, such a device can be implemented in hardware, firmware or software, or some combination of at least two of the same. It should be noted that the functionality associated with any particular controller can be centralized or distributed, whether locally or remotely.

[0039] Moreover, various functions described below can be implemented or supported by one or more computer programs, each of which is formed from computer readable program code and embodied in a computer readable medium. The terms "application" and "program" refer to one or more computer programs, software components, sets of instructions, procedures, functions, objects, classes, instances, related data, or a portion thereof applicable for implementation. The phrase "computer readable program code" includes any type of computer code, including source code, object code, and executable code. The phrase "computer readable medium" includes any type of medium capable of storing computer readable program code, such as a read only memory (ROM), random access memory (RAM), a hard disk drive, a compact disc (CD), a digital video disc (DVD), or any other type of memory. A "non-transitory" computer readable medium excludes wired, wireless, optical, or other communication links. The non-transitory computer readable medium includes a medium that can store data for a period of time consisting of access by a computer and subsequent modification of the data by the computer, e.g., a rewritable optical disc or an erasable memory device.

[0040] Definitions for certain words and phrases are provided throughout this patent document, and those of ordinary skill in the art will understand that in many, if not most instances, such definitions apply to prior as well as future uses of such defined words and phrases.

[0041] The discussion of Figures 1 to 21And various embodiments herein used to describe the principles of the present disclosure are merely for illustration and should not be construed as limiting the scope of the present disclosure in any way. It will be appreciated by persons skilled in the art that the principles of the present disclosure can be implemented in any suitably arranged system or device.

[0042] 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. Throughout the specification, a layer (or a layer device) can also be referred to as an entity. Hereinafter, the operational principles of the present disclosure will be described in detail with reference to the accompanying drawings. In the following description, well-known functions or configurations will not be described in detail because they will obscure the present disclosure with unnecessary detail. The terms used in the present specification are defined in consideration of functions used in the present disclosure, and can be changed according to the intention of a user or an operator or a common practice. Accordingly, the definition of the terms should be understood based on the entire description of the present specification.

[0043] For the same reason, in the drawings, some elements can be exaggerated, omitted, or roughly shown. In addition, the size of each element does not completely correspond to the actual size of each element. In each drawing, the same or corresponding elements are given the same reference numerals.

[0044] The advantages and features of the present disclosure and a method of achieving the same can be more readily understood through the following detailed description of the embodiments of the present disclosure and the accompanying drawings. However, the present disclosure can be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the concept of the present disclosure to those skilled in the art. Accordingly, the scope of the present disclosure is defined by the appended claims. Throughout the specification, the same drawing reference numerals designate the same elements. It will be understood that the blocks in a flowchart or combination of flowcharts can be executed by computer program instructions. Since these computer program instructions can be loaded into a processor of a general-purpose computer, a special-purpose computer, or another programmable data processing device, the instructions executed by the processor of the computer or another programmable data processing device produce units for performing functions described in the blocks of the flowchart.

[0045] The computer program instructions can be stored in a computer-usable or computer-readable memory capable of directing a computer or another programmable data processing apparatus to implement a function in a particular manner, and thus the instructions stored in the computer-usable or computer-readable memory can also produce an article of manufacture containing the instruction units for executing the functions described in the flowchart blocks. The computer program instructions can also be loaded into a computer or another programmable data processing apparatus, and thus the instructions for operating the computer or another programmable data processing apparatus by generating a process executed by the computer when a series of operations are performed in the computer or another programmable data processing apparatus can provide operations for executing the functions described in the flowchart blocks.

[0046] Furthermore, each block can represent a module, a segment, or a portion of code, which includes one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions mentioned in the blocks can occur out of order. For example, depending on the functions, two blocks that are consecutive can also be executed simultaneously or in reverse order.

[0047] As used herein, the term "unit" refers to a software element or a hardware element such as a field-programmable gate array (FPGA) or an application-specific integrated circuit (ASIC) and performs a specific function. However, the term "unit" is not limited to software or hardware. The "unit" can be formed so as to be in an addressable storage medium or can be formed so as to operate one or more processors. Thus, for example, the term "unit" can include elements (e.g., software elements, object-oriented software elements, class elements, and task elements), processes, functions, attributes, procedures, subroutines, segments of program codes, drivers, firmware, microcodes, circuits, data, databases, data structures, tables, arrays, or variables.

[0048] The functions provided by the elements and "units" can be combined into a smaller number of elements and "units" or can be divided into additional elements and "units." Furthermore, the elements and "units" can be implemented to reproduce one or more central processing units (CPUs) in an apparatus or a secure multimedia card. In addition, the "units" can include at least one processor in embodiments of the disclosure. In the following description of the disclosure, well-known functions or configurations are not described in detail because they will obscure the disclosure with unnecessary detail.

[0049] Hereinafter, for convenience of explanation, the disclosure uses terms and names defined in the 3rd Generation Partnership Project Long Term Evolution (3GPP LTE) standard. However, the disclosure is not limited to the described terms and names, but can also be applied to systems following other standards.

[0050] In the disclosure, an evolved node B (eNB) can be used interchangeably with a next-generation node B (gNB) for convenience of explanation. That is, a base station (BS) described by the eNB can represent a gNB. In the following description, the term "base station" refers to an entity for allocating resources to a user equipment (UE), and can be used interchangeably with at least one of a gNode B, an eNode B, a node B, a base station (BS), a radio access unit, a base station controller (BSC), or a node on a network. The term "terminal" can be used interchangeably with a user equipment (UE), a mobile station (MS), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing a communication function. However, the disclosure is not limited to the aforementioned examples. Specifically, the disclosure is applicable to 3GPP New Radio (NR) (or 5th-Generation (5G)) mobile communication standards. In the following description, the term eNB can be used interchangeably with the term gNB for convenience of explanation. That is, a base station explained as an eNB can also indicate a gNB. The term UE can also indicate a mobile phone, an NB-IoT device, a sensor, and other wireless communication devices.

[0051] The above-described Figures 1 to 21 The various embodiments discussed in the following detailed description of the present disclosure are merely for the purpose of illustration and should not be construed as limiting the scope of the present disclosure in any way. It will be appreciated by one skilled in the art that the principles of the present disclosure can be implemented in any suitably arranged system or device.

[0052] In recent years, several broadband wireless technologies have been developed to meet the growing number of broadband subscribers and provide more and better applications and services. Second-generation wireless communication systems have been developed to provide voice services while ensuring user mobility. Third-generation wireless communication systems support not only voice services but also data services. In recent years, fourth-generation wireless communication systems have been developed to provide high-speed data services. However, at present, fourth-generation wireless communication systems cannot meet the growing demand for high-speed data services due to resource shortages. Therefore, a fifth-generation wireless communication system (also referred to as a next-generation radio or NR) is being developed to meet the growing demand for high-speed data services, supporting ultra-reliability and low-latency applications.

[0053] The fifth generation wireless communication system supports not only lower frequency bands but also higher frequency (mmWave) bands, e.g., 10 GHz to 100 GHz, so as to accomplish higher data rates. To mitigate propagation loss of the radio waves and increase the transmission distance, the beamforming, massive Multiple-Input Multiple-Output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna, an analog beam forming, large scale antenna techniques are being considered in the fifth generation wireless communication system. Also, the fifth generation wireless communication system anticipates an implementation of an improved small cell, a cloud Radio Access Network (RAN), an ultra-dense network, a deep-into-millimeter wave, a device-to-device (D2D) communication, a wireless backhaul, a cooperative communication, a coordinated multi-Points (CoMP), a reception / transmission point (RTP), a network influence, a network slicing, a topological slicing, a multi-antenna, a distributed antenna, a RAN intelligence, a smart and connected things, a big data, etc. In addition, the fifth generation wireless communication system is expected to accommodate various services / applications such as an enhanced Mobile Broad Band (eMBB), a massive Machine Type Communication (mMTC), an Ultra-Reliable Low Latency Communication (URLLC) etc. The eMBB is a service / application requiring a high data rate and is expected to be implemented in 4G LTE system. The mMTC is a service / application requiring a high connection density and is expected to be implemented in the Internet of Things (IoT) / Internet of Everything (IoE). The URLLC is a service / application requiring a high reliability and a low latency and is expected to be implemented in a vehicle-to-everything (V2X) communication, a machine type communication (MTC), etc.

[0054] In a fifth generation wireless communication system operating in a higher frequency (millimeter wave) band, a UE and a gNB communicate with each other using beamforming. The beamforming technique is used to mitigate a propagation path loss and increase a propagation distance in order to communicate in a higher frequency band. The beamforming enhances a transmission and reception performance using a high-gain antenna. The beamforming can be classified into transmission (TX) beamforming performed in a transmission end and reception (RX) beamforming performed in a reception end. In general, the TX beamforming allows a region where a propagation arrives to be densely located in a specific direction by using a plurality of antennas to increase directivity. In this case, the aggregation of the plurality of antennas can be referred to as an antenna array, and each antenna included in the array can be referred to as an array element. The antenna array can be configured in various forms, such as a linear array, a planar array, etc. The use of the TX beamforming results in an increase in directivity of a signal, thereby increasing a propagation distance. In addition, since the signal is almost not transmitted in a direction other than the directivity direction, signal interference acting on another reception end is significantly reduced. The reception end can perform beamforming on an RX signal by using an RX antenna array. The RX beamforming increases an RX signal strength transmitted in a specific direction by allowing a propagation to be concentrated in the specific direction, and excludes a signal transmitted in a direction other than the specific direction from the RX signal, thereby providing an effect of blocking an interference signal. By using the beamforming technique, a transmitter can generate a plurality of transmission beam patterns in different directions. Each of the transmission beam patterns can also be referred to as a transmission (TX) beam. A wireless communication system operating in a high frequency transmits a signal in a cell using a plurality of narrow TX beams, and each narrow TX beam provides coverage to a part of the cell. The narrower the TX beam, the higher the antenna gain, and thus the greater the propagation distance of a signal transmitted using the beamforming. A receiver can also generate a plurality of reception (RX) beam patterns in different directions. Each of the reception patterns can also be referred to as a reception (RX) beam.

[0055] The fifth generation wireless communication system supports standalone mode of operation as well as dual connectivity (DC). In DC, a multi-Rx / Tx UE can be configured to utilize resources provided by two different nodes (or NBs) connected via a non-ideal backhaul. One node acts as a master node (MN) and the other as a secondary node (SN). The MN and SN are connected via a network interface and at least the MN is connected to the core network. NR also supports multi-RAT dual connectivity (MR-DC) operation, whereby a UE in RRC_CONNECTED is configured to utilize radio resources provided by two distinct schedulers, located in two different nodes connected via a non-ideal backhaul and offering E-UTRA (i.e. if the nodes are ng-eNBs) or NR access (i.e. if the nodes are gNBs). In NR, for a UE in RRC_CONNECTED not configured with CA / DC, there is only one serving cell, which comprises the primary cell. For a UE in RRC_CONNECTED configured with CA / DC, the term "serving cells" is used to denote the set of cells comprising a particular cell and all secondary cells. In NR, the term master cell group (MCG) refers to the set of serving cells associated with the master node, which comprises the PCell and optionally one or more SCells. In NR, the term secondary cell group (SCG) refers to the set of serving cells associated with the secondary node, which comprises the PSCell and optionally one or more SCells. In NR, the PCell (primary cell) refers to the serving cell in the MCG operating at the primary frequency, where the UE performs the initial connection establishment procedure, or initiates connection re-establishment procedure. In NR for a UE configured with CA, a Scell is a cell providing additional radio resources on top of a particular cell. The primary SCG cell (PSCell) refers to the serving cell in the SCG where the UE performs random access when performing reconfiguration with sync procedure. For dual connectivity operation, the term SpCell (i.e. specific cell) refers to the PCell of the MCG or the PSCell of the SCG, otherwise the term specific cell refers to the PCell.

[0056] In the fifth generation wireless communication system, physical downlink control channel (PDCCH) is used to schedule DL transmissions on PDSCH and UL transmissions on PUSCH, where downlink control information (DCI) on PDCCH includes: downlink assignment containing at least modulation and coding format, resource allocation, and hybrid-ARQ information related to downlink shared channel (DL-SCH); uplink scheduling grant containing at least modulation and coding format, resource allocation, and hybrid-ARQ information related to UL-SCH. In addition to scheduling, PDCCH can also be used for: activation and deactivation of configured PUSCH transmission with configured grant; activation and deactivation of PDSCH semi-persistent transmission; informing one or more UEs of slot format; informing one or more UEs of PRB and OFDM symbol, where the UE can assume no transmission for the UE; transmission of TPC command for PUCCH and PUSCH; transmission of one or more TPC commands for SRS transmission by one or more UEs; switching the active bandwidth part of a UE; initiating a random access procedure. According to the corresponding search space configuration, the UE monitors a set of PDCCH candidates in a configured monitoring occasion in one or more configured control resource sets (CORESET). A CORESET consists of a set of PRBs with a time duration of 1 to 3 OFDM symbols. Resource units resource element groups (REGs) and control channel elements (CCEs) are defined within a CORESET, where each CCE includes a set of REGs. Control channels are formed by aggregation of CCEs. Different code rates of control channels are achieved by aggregating different numbers of CCEs. Interleaved and non-interleaved CCE-to-REG mapping is supported in a CORESET. Polar coding is used for PDCCH. Each resource element group carrying PDCCH carries its own DMRS. QPSK modulation is used for PDCCH.

[0057] In the fifth generation wireless communication system, for each configured BWP, gNB signals a list of search space configurations, where each search configuration is uniquely identified by an identifier. The identifier of the search space configuration is explicitly signaled by the gNB which will be used for specific purposes such as paging reception, SI reception, random access response reception. In NR, a search space configuration includes parameters monitoring-periodicity-PDCCH-slot, monitoring-offset-PDCCH-slot, monitoring-symbols-PDCCH-within-slot and duration. UE uses the parameters PDCCH monitoring periodicity (monitoring-periodicity-PDCCH-slot), PDCCH monitoring offset (monitoring-offset-PDCCH-slot) and PDCCH monitoring pattern (monitoring-symbols-PDCCH-within-slot) to determine the PDCCH monitoring occasions within a slot. The PDCCH monitoring occasions exist in slots 'x' to x+duration, where the slot with number 'x' in radio frame with number 'y' satisfies the following equation 1:

[0058] [Equation 1]

[0059] (y*(number of slots in a radio frame) + x - monitoring-offset-PDCCH-slot) mod (monitoring-periodicity-PDCCH-slot) = 0.

[0060] The starting symbol of the PDCCH monitoring occasion in each slot with PDCCH monitoring occasions is given by intra-slot-monitoring-symbol-PDCCH. The length of the PDCCH monitoring occasion (in symbols) is given in the coreset associated with the search space. The search space configuration includes an identifier of the coreset configuration associated with it. For each configured BWP, the gNB signals a list of coreset configurations, where each coreset configuration is uniquely identified by an identifier. For example, each radio frame has a duration of 10 ms. A radio frame is identified by a radio frame number or a system frame number. Each radio frame includes a number of slots, where the number of slots in a radio frame and the duration of a slot depend on the subcarrier spacing. The number of slots in a radio frame and the duration of a slot depend on each supported SCS and are pre-defined in NR. Each coreset configuration is associated with a list of transmission configuration indicator (TCI) states. Each TCI state configures one DL RS ID (SSB or CSI RS). The list of TCI states corresponding to a coreset configuration is signaled by the gNB via RRC signaling. One of the TCI states in the list of TCI states is activated by the gNB and indicated to the UE. The TCI state indicates the DL TX beam (the DL TX beam is quasi co-located (QCL) with the SSB / CSI RS of the TCI state) used by the gNB to transmit the PDCCH in the PDCCH monitoring occasion of the search space.

[0061] In fifth generation wireless communication systems, bandwidth adaptation (BA) is supported. With BA, the receive and transmit bandwidth of a UE does not have to be as large as the bandwidth of a cell and can be adjusted: a bandwidth change can be ordered (e.g. to shrink during times of lower activity to save power); a location can be moved in the frequency domain (e.g. to improve scheduling flexibility); and a subcarrier spacing change can be ordered (e.g. to allow for different services). A subset of the overall cell bandwidth of a cell is referred to as a bandwidth part (BWP). BA is realized by configuring a BWP for an RRC connected UE and telling the UE which configured BWP is currently active. When BA is configured, a UE only needs to monitor PDCCH on one active BWP, i.e. it does not have to monitor PDCCH on the entire DL frequency of a serving cell. In RRC connected state, one or more DL and UL BWPs are configured for a UE per configured serving cell (i.e. PCell or SCell). For an activated serving cell, there is always one active UL and DL BWP at any point in time. BWP switching for a serving cell is used to simultaneously activate an inactive BWP and deactivate an active BWP. BWP switching is controlled by PDCCH indicating downlink assignment or uplink grant, by the bwp-InactivityTimer, by RRC signaling or by the MAC entity itself after a random access procedure is initiated. After adding a SpCell or activating a SCell, the DL BWP and UL BWP indicated by firstActiveDownlinkBWP-Id and firstActiveUplinkBWP-Id, respectively, are active and no PDCCH indicating downlink assignment or uplink grant is received. The active BWP of a serving cell is indicated by RRC or PDCCH. For unpaired spectrum, DL BWPs are paired with UL BWPs and BWP switching is common for UL and DL. After the BWP inactivity timer expires, the UE switches the active DL BWP to the default DL BWP or the initial DL BWP (if no default DL BWP is configured).

[0062] In 5G wireless communication systems, random access (RA) is supported. Random access (RA) is used to achieve uplink (UL) time synchronization. RA is used during the following actions: initial access, handover, radio resource control (RRC) connection reestablishment procedure, scheduling request transmission, secondary cell group (SCG) addition / modification, beam failure recovery, and data or control information transmission in UL by a non-synchronized UE in RRC connected state. Several types of random access procedures are supported.

[0063] Contention-based random access (CBRA): This is also referred to as 4-step CBRA. In this type of random access, the UE first transmits a random access preamble (also referred to as Msgl) and then waits for a random access response (RAR) in a RAR window. The RAR is also referred to as Msg2. The next generation NodeB (gNB) transmits the RAR on a physical downlink shared channel (PDSCH). The PDCCH scheduling the PDSCH carrying the RAR is addressed to a RA-radio network temporary identifier (RA-RNTI). The RA-RNTI identifies the time-frequency resource (also referred to as a physical RA channel (PRACH) occasion or PRACH transmission (TX) occasion or RA channel (RACH) occasion) in which the gNB detected the RA preamble. The RA-RNTI is calculated as follows: RA-RNTI = 1 + s_id + 14 * t_id + 14 * 80 * f_id + 14 * 80 * 8 * ul_carrier_id, where s_id is the index of the first orthogonal frequency-division multiplexing (OFDM) symbol of the PRACH occasion in which the UE has transmitted Msgl, i.e., the RA preamble; 0 < s_id < 14; t_id is the index of the first slot of the PRACH occasion (0 < t_id < 80); f_id is the index of the PRACH occasion within the slot in the frequency domain (0 < f_id < 8), and ul_carrier_id is the UL carrier used for Msgl transmission (normal UL (NUL) carrier is 0 and supplemental UL (SUL) carrier is 1). The gNB can multiplex several RARs for various random access preambles detected by the gNB in the same RAR medium access control (MAC) protocol data unit (PDU). The RAR in the MAC PDU corresponds to the UE’s RA preamble transmission if the RAR includes the RA preamble identifier (RAPID) of the RA preamble transmitted by the UE. If no RAR corresponding to its RA preamble transmission is received during the RAR window and the UE has not transmitted the RA preamble a configurable (configured by the gNB in the RACH configuration) number of times, the UE goes back to the first step, i.e., selects a random access resource (preamble / RACH occasion) and transmits the RA preamble. Backoff can be applied before going back to the first step.

[0064] If a RAR corresponding to its RA preamble transmission is received, the UE transmits message 3 (Msg3) in the UL grant received in the RAR. Msg3 includes messages such as RRC connection request, RRC connection reestablishment request, RRC handover confirm, scheduling request, SI request, etc. It can include a UE identity (i.e., cell radio network temporary identifier (C-RNTI) or system architecture evolution (SAE)-temporary mobile subscriber identity (S-TMSI) or a random number). After transmitting Msg3, the UE starts a contention resolution timer. While the contention resolution timer is running, if the UE receives a physical downlink control channel (PDCCH) addressed to the C-RNTI included in Msg3, the contention resolution is considered successful, the contention resolution timer stops and the RA procedure is completed. While the contention resolution timer is running, if the UE receives a contention resolution MAC control element (CE) including the contention resolution identity of the UE (first X bits of the common control channel (CCCH) service data unit (SDU) transmitted in Msg3), the contention resolution is considered successful, the contention resolution timer stops and the RA procedure is completed. If the contention resolution timer expires and the UE has not transmitted the RA preamble a configurable number of times, the UE goes back to the first step, i.e., selecting a random access resource (preamble / RACH occasion) and transmitting the RA preamble. Backoff can be applied before going back to the first step.

[0065] Contention free random access (CFRA): This is also referred to as legacy CFRA or 4-step CFRA. The CFRA procedure is used for scenarios such as handover that requires low latency, timing advance establishment for secondary cells (Scell), etc. The evolved node B (eNB) assigns a dedicated random access preamble to the UE. The UE transmits the dedicated RA preamble. The ENB transmits a RAR on PDSCH addressed to RA-RNTI. The RAR conveys the RA preamble identifier and timing alignment information. The RAR can also include an UL grant. The RAR is transmitted in a RAR window similar to the contention based RA (CBRA) procedure. After receiving a RAR including the RA preamble identifier (RAPID) of the RA preamble transmitted by the UE, the CFRA is considered to be successfully completed. In case of initiating RA for beam failure recovery, the CFRA is considered to be successfully completed if a PDCCH addressed to C-RNTI is received in the search space for beam failure recovery. If the RAR window expires and the RA is not successfully completed, and the UE has not transmitted the RA preamble a configurable (configured by gNB in RACH configuration) number of times, the UE retransmits the RA preamble.

[0066] For certain events, such as handover and beam failure recovery, if one or more dedicated preambles are assigned to the UE, the UE determines whether to transmit a dedicated preamble or a non-dedicated preamble during the first step of random access, i.e., during random access resource selection for Msgl transmission. Dedicated preambles are typically provided for a subset of SSBs / CSI-RSs. If none of the SSBs / CSI RSs among which the gNB provided it with a contention-free random access resource (i.e., dedicated preamble / RO) has a DL RSRP above a threshold, the UE selects a non-dedicated preamble. Otherwise, the UE selects a dedicated preamble. Thus, in a RA procedure, one random access attempt can be CFRA, while other random access attempts can be CBRA.

[0067] 2-step Contention Based Random Access (2-step CBRA): In the first step, the UE transmits a random access preamble on PRACH and a payload (i.e., MAC PDU) on PUSCH. The random access preamble and payload transmission is also referred to as MsgA. In the second step, after the MsgA transmission, the UE monitors for a response from the network (i.e., gNB) within a configured window. The response is also referred to as MsgB. If a CCCH SDU is transmitted in the MsgA payload, the UE uses the contention resolution information in MsgB to perform contention resolution. Contention resolution is successful if the contention resolution identity received in MsgB matches the first 48 bits of the CCCH SDU transmitted in MsgA. If a C-RNTI is transmitted in the MsgA payload, contention resolution is successful if the UE receives a PDCCH addressed to the C-RNTI. If contention resolution is successful, the random access procedure is considered to be successfully completed. Instead of contention resolution information corresponding to the transmitted MsgA, MsgB can include fallback information corresponding to the random access preamble transmitted in MsgA. If fallback information is received, the UE transmits Msg3 and performs contention resolution using Msg4 as in the CBRA procedure. If contention resolution is successful, the random access procedure is considered to be successfully completed. If contention resolution fails upon fallback (i.e., upon transmission of Msg3), the UE retransmits MsgA. If the configured window in which the UE monitors for a network response after transmitting MsgA expires and the UE does not receive a MsgB including contention resolution information or fallback information as described above, the UE retransmits MsgA. If the random access procedure is not successfully completed even after transmitting MsgA a configurable number of times, the UE falls back to the 4-step RACH procedure, i.e., the UE transmits only a PRACH preamble.

[0068] The MsgA payload can include one or more of the following: a common control channel (CCCH) service data unit (SDU), a dedicated control channel (DCCH) SDU, a dedicated traffic channel (DTCH) SDU, a buffer status report (BSR) MAC control element (CE), a power headroom report (PHR) MAC CE, SSB information, a C-RNTI MAC CE, or padding. The MsgA can include a UE ID (e.g., a random ID, an S-TMSI, a C-RNTI, a resume ID, etc.) and a preamble in the first step. The UE ID can be included in the MAC PDU of the MsgA. The UE ID such as a C-RNTI can be carried in a MAC CE, where the MAC CE is included in the MAC PDU. Other UE IDs such as a random ID, an S-TMSI, a C-RNTI, a resume ID, etc. can be carried in a CCCH SDU. The UE ID can be one of a random ID, an S-TMSI, a C-RNTI, a resume ID, an IMSI, an idle mode ID, an inactive mode ID, etc. The UE ID can be different in different scenarios when the UE performs the RA procedure. When the UE performs the RA upon power on (before attaching to the network), the UE ID is a random ID. When the UE performs the RA in the idle state after attaching to the network, the UE ID is an S-TMSI. If the UE has an assigned C-RNTI (e.g., in the connected state), the UE ID is the C-RNTI. In the case that the UE is in the inactive state, the UE ID is a resume ID. In addition to the UE ID, some additional ctrl information can be sent in the MsgA. The control information can be included in the MAC PDU of the MsgA. The control information can include one or more of the following: a connection request indication, a connection resume request indication, an SI request indication, a buffer status indication, beam information (e.g., one or more DL TX beam IDs or SSB IDs), beam failure recovery indication / information, a data indicator, a cell / BS / TRP switch indication, a connection re-establishment indication, a reconfiguration complete or handover complete message, etc.

[0069] 2-step contention free random access (2-step CFRA): In this case, the gNB assigns a dedicated random access preamble and PUSCH resource to be used for MsgA transmission to the UE. The RO to be used for preamble transmission can also be indicated. In the first step, the UE transmits a random access preamble on PRACH and a payload on PUSCH using the contention free random access resource (i.e., dedicated preamble / PUSCH resource / RO). In the second step, after the MsgA transmission, the UE monitors for a response from the network (i.e., gNB) within a configured window. If the UE receives a PDCCH addressed to C-RNTI, the random access procedure is considered to be successfully completed. If the UE receives a fallback message corresponding to the preamble it transmitted, the random access procedure is considered to be successfully completed.

[0070] For certain events, such as handover and beam failure recovery, if a dedicated preamble and PUSCH resource is assigned to the UE, the UE determines whether to transmit a dedicated preamble or a non-dedicated preamble during the first step of random access, i.e., during the random access resource selection for MsgA transmission. Dedicated preambles are typically provided for a subset of SSBs / CSI-RSs. If none of the SSBs / CSI-RSs in which the gNB provided the UE with contention free random access resources (i.e., dedicated preamble / RO / PUSCH resource) have a DL RSRP above a threshold, the UE selects a non-dedicated preamble. Otherwise, the UE selects a dedicated preamble. Thus, during a RA procedure, one random access attempt can be 2-step CFRA, while other random access attempts can be 2-step CBRA.

[0071] Upon initiating a random access procedure, the UE first selects a carrier (SUL or NUL). If the gNB explicitly signals a carrier for the random access procedure, the UE selects the signaled carrier to perform the random access procedure. If the gNB does not explicitly signal a carrier for the random access procedure; and if the serving cell of the random access procedure is configured with a supplementary uplink, and if the RSRP of the downlink pathloss reference is less than rsrp-ThresholdSSB-SUL: the UE selects the SUL carrier to perform the random access procedure. Otherwise, the UE selects the NUL carrier to perform the random access procedure. After selecting the UL carrier, the UE determines the UL and DL BWPs to use for the random access procedure as specified in the 3GPP standard specification. Then, the UE determines whether to perform 2-step or 4-step RACH for this random access procedure.

[0072] - If this random access procedure is initiated by a PDCCH order, and if the ra-PreambleIndex explicitly provided by the PDCCH is not 0b000000, the UE selects 4-step RACH.

[0073] - Otherwise, if the gNB signaled 2-step contention-free random access resources for this random access procedure, the UE selects 2-step RACH.

[0074] - Otherwise, if the gNB signaled 4-step contention-free random access resources for this random access procedure, the UE selects 4-step RACH.

[0075] - Otherwise, if the selected UL BWP for this random access procedure is configured with only 2-step RACH resources, the UE selects 2-step RACH.

[0076] - Otherwise, if the selected UL BWP for this random access procedure is configured with only 4-step RACH resources, the UE selects 4-step RACH.

[0077] - Otherwise, if the selected UL BWP for this random access procedure is configured with 2-step and 4-step RACH resources,

[0078] - If the RSRP of the downlink pathloss reference is below a configured threshold, the UE selects 4-step RACH. Otherwise, the UE selects 2-step RACH.

[0079] In a fifth generation wireless communication system, a Node B (gNB) or base station in a cell broadcasts synchronization signals and PBCH blocks (SSB) consists of a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) and system information. The system information includes common parameters needed for communication in the cell.

[0080] In a fifth generation wireless communication system, the RRC can be in one of the following states: RRC idle (RRC_IDLE), RRC inactive (RRC_INACTIVE) and RRC connected. When an RRC connection has been established, the UE is in the RRC connected state or the RRC inactive state. If this is not the case, i.e. no RRC connection has been established, the UE is in the RRC idle state. The RRC state can be further characterized as follows:

[0081] In RRC idle, UE-specific DRX can be configured by upper layers. The UE monitors short messages transmitted with P-RNTI by DCI; monitors the paging channel for CN paging using 5G-S-TMSI; performs neighbor cell measurements and cell (re)selection; acquires system information and can send an SI request if configured; the UE performs logging of available measurements and location and time of the UE configured with logged measurements.

[0082] In RRC inactive, UE-specific DRX can be configured by upper layers or by RRC layer; UE stores UE Inactive AS context; RAN-based notification area is configured by RRC layer. UE monitors short messages transmitted with P-RNTI by DCI; UE monitors paging channel for CN paging using 5G-S-TMSI and RAN paging using full I-RNTI; UE performs neighbor cell measurements and cell (re)selection; UE performs RAN-based notification area update periodically and when moving outside the configured RAN-based notification area; UE acquires system information and can send SI request if configured; UE performs logging of available measurements and location and time of the UE configured with logged measurements.

[0083] In RRC connected, UE stores AS context and transfer of unicast data to / from the UE occurs. UE monitors short messages transmitted with P-RNTI by DCI if configured; monitors control channels associated with shared data channels to determine if data is scheduled for the UE; provides channel quality and feedback information; monitors to perform neighbor cell measurements and measurement reporting; acquires system information.

[0084] In RRC connected, the network can initiate suspension of the RRC connection by sending an RRCRelease with a suspend configuration. When the RRC connection is suspended, the UE stores the UE Inactive AS context and any configuration received from the network and transitions to the RRC Inactive state. If the UE is configured with SCG, the UE releases the SCG configuration when initiating the RRC connection resume procedure. The RRC message for suspending the RRC connection is integrity protected and ciphered.

[0085] When the UE needs to transition from RRC Inactive state to RRC Connected state, the resumption of the suspended RRC connection is initiated by upper layers, or by RRC layer to perform RNA update, or by RAN paging from NG-RAN. When the RRC connection is resumed, the network configures the UE according to the RRC connection resume procedure based on the stored UE Inactive AS context and any RRC configuration received from the network. The RRC connection resume procedure reactivates AS security and re-establishes SRBs and DRBs. In response to the request to resume the RRC connection, the network can resume the suspended RRC connection and send the UE to RRC Connected, or reject the request to resume and send the UE to RRC Inactive (using a wait timer), or directly re-suspend the RRC connection and send the UE to RRC Inactive, or directly release the RRC connection and send the UE to RRC Idle, or instruct the UE to initiate NAS level recovery (in which case the network sends an RRC setup message).

[0086] After initiating the resumption procedure, the UE: applies the default L1 parameter values as specified in the corresponding physical layer specification, in addition to the parameters whose values are provided in SIB1; applies the default MAC cell group configuration; applies the CCCH configuration; starts timer T319; applies the timeAlignmentTimerCommon included in SIB1; applies the default SRB1 configuration; sets the variable pendingRNA-Update to false; initiates transmission of the RRCResumeRequest message or RRCResumeRequest1; recovers the RRC configuration, RoHC state, stored QoS flow to DRB mapping rules and KgNB and KRRCint keys from the stored UE inactive AS context, except for the following: masterCellGroup, mrdc-SecondaryCellGroup (if stored) and pdcp-Config; sets resumeMAC-I to the 16 least significant bits of the MAC-I calculated using the K RRCint key in the UE inactive AS context and the previously configured integrity protection algorithm and all input bits of COUNT, BEARER and DIRECTION set to binary one; derives K gNB from the stored nextHopChainingCount value based on the current K gNB key; derives K RRCenc from the stored nextHopChainingCount value based on the current K RRCint key; derives K UPint from the stored nextHopChainingCount value based on the current K UPenc key; uses the configured algorithm and K RRCint key; uses the configured algorithm and K UPint key, configures lower layers to apply integrity protection for all signalling radio bearers except SRB0, i.e. integrity protection can be applied to all subsequent messages received and transmitted by the UE; configures lower layers to apply ciphering for all signalling radio bearers except SRB0 and the configured ciphering algorithm, K RRCenc key derived in this subclause; configures lower layers to apply integrity protection for all signalling radio bearers except SRB0, i.e. integrity protection can be applied to all subsequent messages received and transmitted by the UE; configures lower layers to apply ciphering for all signalling radio bearers except SRB0 and the configured ciphering algorithm, K UPenc key, i.e. ciphering configuration can be applied to all subsequent messages received and transmitted by the UE; re-establishes the PDCP entity for SRB1; recovers SRB1; and transmits RRCResumeRequest or RRCResumeRequest1.

[0087] Figure 1 and Figure 2 An example of a BFR MAC CE according to embodiments of the disclosure is shown. Figure 1An example of SCell beam failure recovery (BFR) MAC CE is shown and the truncated SCell BFR MAC CE with the highest ServCellIndex of the MAC entity's configured SCell with beam failure detection (BFD) is less than 8. In addition, Figure 2 An example of SCell BFR MAC CE is shown and the truncated SCell BFR MAC CE with the highest ServCellIndex of the MAC entity's configured SCell with BFD is equal to or higher than 8.

[0088] The fifth generation wireless communication system supports beam failure detection and recovery mechanisms at the UE for serving cells. This includes beam failure detection, new candidate beam identification, beam failure recovery request transmission, and monitoring for response to the beam failure recovery request. For beam failure detection of a serving cell, the UE is configured with a list of beam failure detection RS (based on SSB or CSI-RS) for that serving cell. The UE can periodically monitor these RS. Beam failure is detected on a serving cell if the number of consecutively detected beam failure instances exceeds a configured maximum number (beamFailurelnstanceMaxCount) within a configured time (beamFailureDetectionTimer). A beam failure instance means a hypothetical PDCCH BLER based on measurement of the beam failure detection RS is above a threshold for all beam failure detection RS. Beam failure detection can be configured for zero or one or more serving cells. In a beam failure instance, the lower layer (i.e., PHY layer) sends an indication to the MAC layer (i.e., MAC entity). The MAC entity in the UE for each serving cell configured for beam failure detection can perform the following operations:

[0089] 1> if a beam failure instance indication has been received from lower layers:

[0090] 2> start or restart the beamFailureDetectionTimer;

[0091] 2> increment the BFI counter by 1;

[0092] 2> if the BFI counter >= beamFailurelnstanceMaxCount:

[0093] 3> if the serving cell is an SCell:

[0094] 4> trigger beam failure recovery (BFR) for this serving cell;

[0095] 3> else:

[0096] 4> initiate a random access procedure on the SCell.

[0097] 1> if the beamFailureDetectionTimer expires; or

[0098] 1> if the beamFailureDetectionTimer, the beamFailureInstanceMaxCount or any reference signal used for beam failure detection is reconfigured by upper layers (i.e. RRC) associated with this serving cell:

[0099] 2> set the BFI counter to 0.

[0100] 1> if the serving cell is the SpCell and the random access procedure initiated for SpCell beam failure recovery has successfully completed:

[0101] 2> set the BFI counter to 0;

[0102] 2> stop the beamFailureRecoveryTimer (if configured);

[0103] 2> consider the beam failure recovery procedure successfully completed.

[0104] 1> else, if the serving cell is an SCell and a PDCCH addressed to C-RNTI indicating an uplink grant for a new transmission is received for the HARQ process for which the BFR MAC CE 100 containing beam failure recovery information or the truncated BFR MAC CE 100 was transmitted; or

[0105] 1> if the SCell is deactivated:

[0106] 2> set the BFI counter to 0;

[0107] 2> consider the beam failure recovery procedure successfully completed and cancel all triggered BFRs for this serving cell.

[0108] The MAC entity can:

[0109] 1> if the beam failure recovery procedure determines that at least one BFR has been triggered and not cancelled:

[0110] 2> if UL-SCH resources are available for a new transmission and if, as a result of logical channel prioritization (LCP), the UL-SCH resources can accommodate the BFR MAC CE 100 and its subheaders:

[0111] 3> indicate the multiplexing and assembly procedure to generate the BFR MAC CE 100.

[0112] 2> Otherwise, if UL-SCH resources are available for a new transmission and if, as a result of LCP, the UL-SCH resources can accommodate the truncated BFR MAC CE 100 and its subheader:

[0113] 3> indicate the multiplexing and assembly procedure to generate the truncated BFR MAC CE 100.

[0114] 2> Otherwise:

[0115] 3> for each SCell for which BFR has been triggered and not cancelled, trigger SR for SCell beam failure recovery.

[0116] When transmitting a MAC PDU, all BFRs triggered prior to MAC PDU assembly for beam failure recovery of an SCell can be cancelled and this PDU includes a BFR MAC CE 100 or a truncated BFR MAC CE 100 containing beam failure information for that SCell.

[0117] beamFailureInstanceMaxCount, beamFailureDetectionTimer and beamFailureRecoveryTimer for beam failure recovery procedure are specific to a serving cell. The BFI counter is maintained separately for each serving cell configured with beam failure detection.

[0118] The MAC CE for BFR includes:

[0119] - a BFR MAC CE 100; or

[0120] - a truncated BFR MAC CE 100.

[0121] The BFR MAC CE 100 and the truncated BFR MAC CE 100 are identified by a MAC subheader with LCID / eLCID.

[0122] The BFR MAC CE and the truncated BFR MAC CE have variable size. The BFR MAC CE and the truncated BFR MAC CE include a bitmap and beam failure recovery information based on ServCellIndex in ascending order, i.e. octets containing candidate beam availability indication (AC) for SCells indicated in the bitmap. For the BFR MAC CE 100, a single octet bitmap is used when the highest ServCellIndex of SCells of this MAC entity for which beam failure is detected is less than 8 (in Figure 1four octets (as shown in the middle) otherwise. A MAC PDU can contain at most one BFR MAC CE. Figure 2

[0123] For truncated BFR MAC CE, a single octet bitmap is used in the following cases, otherwise four octets are used:

[0124] - the highest ServCellIndex of the SCells of this MAC entity where beam failure is detected is less than 8; or

[0125] - beam failure is detected for SpCell and SpCell is to be indicated in the truncated BFR MAC CE and as a result of LCP, the UL-SCH resources available for transmission cannot accommodate the truncated BFR MAC CE with four octet bitmap and its sub-headers.

[0126] The fields in BFR MAC CE 100, 200 are defined as follows:

[0127] - SP: This field indicates the beam failure detection for SpCell of this MAC entity. SP field is set to 1 to indicate that beam failure is detected for SpCell only if the BFR MAC CE or truncated BFR MAC CE is to be included into the MAC PDU as part of a random access procedure, otherwise, set to 0;

[0128] - C i (BFR MAC CE): This field indicates the beam failure detection and the presence of octet containing AC field for SCell with ServCellIndex i. C i field set to 1 indicates that beam failure is detected and there is an octet containing AC field for SCell with ServCellIndex i. C i field set to 0 indicates that beam failure is not detected and there is no octet containing AC field for SCell with ServCellIndex i. The octets containing AC field are present in ascending order of ServCellIndex;

[0129] - C i (truncated BFR MAC CE): This field indicates the beam failure detection for SCell with ServCellIndex i. C i field set to 1 indicates that beam failure is detected and there can be an octet containing AC field for SCell with ServCellIndex i. C i ​The field indicates that no beam failure is detected and that the SCell with ServCellIndex i does not exist. The octets containing AC field are included in ascending order of ServCellIndex (if exist). The number of octets containing AC field included is maximized without exceeding the available grant size;

[0130] - AC: This field indicates the presence of the candidate RS ID field in this octet. The AC field is set to 1 if at least one of the SSBs in the candidateBeamRSSCellList with SS-RSRP above rsrp-ThresholdBFR or the CSI-RSs in the candidateBeamRSSCellList with CSI-RSRP above rsrp-ThresholdBFR is available. Otherwise, it is set to 0. If the AC field is set to 1, the candidate RS ID field is present. If the AC field is set to 0, the R bit is present instead;

[0131] - Candidate RS ID: This field is set to the index of the SSB in the candidateBeamRSSCellList with SS-RSRP above rsrp-ThresholdBFR or the index of the CSI-RS in the candidateBeamRSSCellList with CSI-RSRP above rsrp-ThresholdBFR. The length of this field is 6 bits.

[0132] - R: Reserved bit set to 0.

[0133] Figure 3 An example wireless network according to embodiments of the present disclosure is illustrated.

[0134] A serving cell can support multiple transmission / reception points (TRPs) 310, 320 and a UE 330 can be simultaneously served by multiple TRPs 310, 320 for improved data rate and reliability. In the current design, there is beam failure detection and recovery for each serving cell. For example, a list of BFD RSs is signaled per serving cell and a list of candidate beam RSs is signaled per serving cell. As shown, if all beams of a TRP 320 of a serving cell fail, no beam failure is detected and thus the TRP 320 cannot serve the UE 330 until all beams of all TRPs of the serving cell fail and beam failure recovery is initiated for the serving cell. The beam failure detection and recovery procedure needs to be enhanced. Figure 3

[0135] ​Beam failure detection configuration.

[0136] In one method of the disclosure, for beam failure detection in a serving cell, the gNB (in RRCReconfiguration message) signals / transmits a beam failure detection configuration including a list of beam failure detection RSs, where in the list, the TRP associated with each RS can be indicated. This beam failure detection configuration is per BWP (or DL BWP). The parameter “trpIndex” can indicate the TRP associated with each RS. The following is an example in the case where there are up to two TRPs in the serving cell. Note that if there is only one TRP in the serving cell, the parameter “trpIndex” can not be included. In the embodiment of the case where there are two TRPs (TRP 0 and TRP 1) in the serving cell, “trpIndex” can be included for RSs associated with TRP 1, and “trpIndex” can not be included for RSs associated with TRP 0. The absence of “trpIndex” can imply that the RS is associated with TRP 0. In the embodiment of the case where there are two TRPs (1st TRP 0 and 2nd TRP) in the serving cell, “trpIndex” can be included for RSs associated with the second TRP, and “trpIndex” can not be included for RSs associated with the first TRP 0. The absence of “trpIndex” can imply that the RS is associated with the first TRP.

[0137] [Table 1]

[0138]

[0139] In an embodiment, radioLinkMonitoringRSPoolIndex (also can be referred to as RS pool index / identifier or RS set index / identifier) can be added instead of trpIndex. Based on this, the UE can identify multiple sets / pools of beam failure detection RSs, where RSs in the same set / pool correspond to the same radioLinkMonitoringRSPoolIndex / RS set index / RS pool index. The RS set corresponding to a TRP has the same radioLinkMonitoringRSPoolIndex / RS set index / RS pool index.

[0140] In another method of the present disclosure, for beam failure detection in a serving cell, the gNB can signal / transmit a beam failure detection configuration where for each TRP of each BWP (or DL BWP) of the serving cell, a list of BFD RSs is signaled separately. Below is an example in the case where there are up to two TRPs in the serving cell. failureDetectionResourcesToAddModList and failureDetectionResourcesToAddModList2 can indicate the list of BFD RSs for different TRPs.

[0141] [Table 2]

[0142]

[0143]

[0144] In an alternative embodiment, the gNB can signal RadioLinkMonitoringConfig IE separately for different TRPs of the serving cell. For example, if there are two TRPs, RadioLinkMonitoringConfig and radioLinkMonitoringConfigl can be signaled separately for the first and second TRPs, respectively, in the BWP-DownlinkDedicated IE of the serving cell (in the RRCReconfiguration message).

[0145] Using one of the above explained signaling methods, the gNB can signal a beam failure detection configuration for a serving cell where multiple sets / pools of beam failure detection RSs are configured (in the RRCReconfiguration message), where each set / pool belongs to a different TRP. Upon receiving the beam failure detection configuration for the serving cell from the gNB according to one of the above explained signaling methods, the UE can identify the multiple sets / pools of beam failure detection RSs, where each set / pool belongs to a different TRP.

[0146] Beam failure recovery configuration.

[0147] In one method of the disclosure, for beam failure recovery, the gNB can signal / transmit (in RRCReconfiguration message) a beam failure recovery configuration including a list of candidate beam RSs, where in the list, the TRP associated with each RS can be indicated. This configuration is per BWP (or DL BWP). The parameter “trpIndex” can indicate the TRP associated with each RS. The following is an example in the case where there are up to two TRPs in SpCell. Note that if there is only one TRP in the serving cell, the parameter “trpIndex” can not be included. In an embodiment in the case where there are two TRPs (TRP 0 and TRP 1) in the serving cell, for RSs associated with TRP 1, “trpIndex” can be included, and for RSs associated with TRP 0, “trpIndex” can not be included. The absence of “trpIndex” can imply that the RS is associated with TRP 0. In an embodiment in the case where there are two TRPs (1st TRP 0 and 2nd TRP) in the serving cell, for RSs associated with the second TRP, “trpIndex” can be included, and for RSs associated with the first TRP 0, “trpIndex” can not be included. The absence of “trpIndex” can imply that the RS is associated with the first TRP.

[0148] [Table 3]

[0149]

[0150]

[0151] The following Table 4 is another example in the case where there are up to two TRPs in SCell. Note that if there is only one TRP in the serving cell, the parameter “trpIndex” can not be included.

[0152] [Table 4]

[0153]

[0154] In an embodiment, instead of trpIndex, ResourceSetIndex (or resource pool index) can be added. Based on this, the UE can identify multiple sets / pools of beam failure recovery RSs, where RSs in the same set / pool correspond to the same ResourceSetIndex / resource pool index. The set of RSs corresponding to a TRP has the same ResourceSetIndex / resource pool index. In the case of SpCell, the UE can also identify the CFRA resource corresponding to each TRP.

[0155] In another method of the present disclosure, for beam failure recovery, the gNB can signal the beam failure recovery configuration where for each TRP of each BWP (or DL BWP) of the serving cell, a list of candidate beam RSs is signaled separately. Table 5 below is an example in case there are up to two TRPs in the serving cell. candidateBeamRSList and candidateBeamRSList2 indicate the list of candidate beam RSs for different TRPs.

[0156] [Table 5]

[0157]

[0158] In an alternative embodiment, the gNB can signal the BeamFailureRecoveryConfig IE separately for different TRPs of the serving cell. For example, if there are two TRPs, the BeamFailureRecoveryConfig / BeamFailureRecoverySCellConfig and BeamFailureRecoveryConfig1 / BeamFailureRecoverySCellConfig1 can be signaled separately for the first and second TRPs in the BWP configuration of the SpCell / SCell (in the RRCReconfiguration message).

[0159] Using one of the above explained signaling methods, the gNB can signal the beam failure recovery configuration for the serving cell (in the RRCReconfiguration message) where multiple sets of candidate beam RSs can be indicated, where each set can belong to a different TRP. Upon receiving the beam failure recovery configuration for the serving cell from the gNB according to the above explained signaling method, the UE can identify multiple sets / pools of candidate beam RSs where each set / pool belongs to a different TRP.

[0160] Method 1:

[0161] Beam failure detection and beam failure recovery triggering for the serving cell:

[0162] Embodiment 1:

[0163] Figure 4 is a flow chart illustrating the beam failure detection and beam failure recovery according to an embodiment of the present disclosure.

[0164] In the method of the present disclosure, the beam failure detection and beam failure recovery triggering for the serving cell is in Figure 4The procedure for beam failure detection for a serving cell is shown in FIG. 4. For beam failure detection in a serving cell, in step S410, the UE can receive, from the gNB, the beam failure detection configuration for the serving cell, as explained previously. There is a beam failure detection configuration for each DL BWP of the serving cell. In step S415, the UE can determine whether the received beam failure detection configuration for the active DL BWP includes beam failure detection RSs for multiple TRPs.

[0165] In step S420, if the beam failure detection configuration for the active DL BWP includes beam failure detection RSs for multiple TRPs, the UE detects a beam failure and triggers beam failure recovery for one or more TRPs of the serving cell, as follows:

[0166] In step S425, the UE (i.e., the PHY layer in the UE) periodically measures the beam failure detection RSs for the TRPs of the serving cell in the beam failure detection configuration.

[0167] In step S430, if all the BFD RSs for the TRPs of the serving cell are below a threshold, or the hypothetical PDCCH BLER determined based on the measurements of the beam failure detection RSs is higher than a threshold for all the beam failure detection RSs for the TRPs:

[0168] In step S435, a beam failure instance for the TRP is considered to have occurred, i.e., the PHY layer sends a beam failure instance indication for the TRP to the MAC layer (or MAC entity).

[0169] Upon receiving the beam failure instance indication for the TRP of the serving cell from the PHY layer,

[0170] In step S440, the MAC layer (or MAC entity) starts or restarts the beamFailureDetectionTimer corresponding to the TRP of the serving cell for which the beam failure instance indication is received from the PHY layer. The beamFailureDetectionTimer is maintained separately for each TRP of the serving cell. The value of the beamFailureDetectionTimer is signaled by the gNB. The value of the beamFailureDetectionTimer can be the same for all the TRPs of the serving cell. Alternatively, the value of the beamFailureDetectionTimer can be configured separately for each TRP of the serving cell.

[0171] In step S445, the MAC layer updates the BFI counter corresponding to the TRP of the serving cell for which the beam failure instance indication is received from the PHY layer. The BFI counter is maintained separately for each TRP of the serving cell.

[0172] If the BFI counter >= beamFailurelnstanceMaxCount for the TRP of the serving cell (in step S450), it is considered that beam failure of the TRP of the serving cell is detected in step S455, and beam failure recovery of the TRP of the serving cell is initiated. The value of beamFailurelnstanceMaxCount is signaled by the gNB. The value of beamFailurelnstanceMaxCount can be the same for all TRPs of the serving cell. Alternatively, the value of beamFailurelnstanceMaxCount can be configured separately for each TRP of the serving cell.

[0173] In step S420, if the beam failure detection configuration of the active DL BWP does not include beam failure detection RSs of multiple TRPs, the UE detects beam failure and triggers beam failure recovery as follows:

[0174] In step S460, the UE (PHY layer) periodically measures the beam failure detection RSs of the serving cell in the beam failure detection configuration.

[0175] In step S465, if all BFD RSs of the serving cell are below the threshold, or the hypothetical PDCCH BLER determined based on the measurements of the beam failure detection RSs is higher than the threshold for all beam failure detection RSs of the serving cell:

[0176] In step S470, it is considered that a beam failure instance occurs, i.e., the PHY layer sends a beam failure instance indication to the MAC layer (or MAC entity).

[0177] Upon receiving the beam failure instance indication of the serving cell from the PHY layer,

[0178] In step S475, the MAC layer starts or restarts the beamFailureDetectionTimer of the serving cell from which the beam failure instance indication is received from the PHY layer. One beamFailureDetectionTimer is maintained for the serving cell.

[0179] In step S480, the MAC layer can update the BFI counter of the serving cell from which the beam failure instance indication is received from the PHY layer. One BFI counter is maintained for the serving cell.

[0180] If the BFI counter >= beamFailurelnstanceMaxCount for the serving cell (in step S485), it is considered that beam failure of the serving cell is detected in step S490, and beam failure recovery of the serving cell is initiated.

[0181] Embodiment 2:

[0182] Figure 5 is a flowchart illustrating beam failure detection and beam failure recovery according to an embodiment of the disclosure.

[0183] In the method of the disclosure, the beam failure detection and beam failure recovery triggering of the serving cell is illustrated in Figure 5 For beam failure detection in the serving cell, in step S510, the UE can receive the beam failure detection configuration of the serving cell from the gNB, as previously explained. There is a beam failure detection configuration for each DL BWP of the serving cell. In step S515, the UE can determine whether the received beam failure detection configuration of the active DL BWP includes multiple sets / pools of beam failure detection RSs.

[0184] In step S520, if the beam failure detection configuration of the active DL BWP includes multiple sets / pools of beam failure detection RSs, the UE detects beam failure and triggers beam failure recovery of one or more TRPs of the serving cell (i.e., one or more sets / pools of BFD RSs), as follows:

[0185] In step S525, the UE (i.e., the PHY layer in the UE) periodically measures the beam failure detection RSs in the multiple sets / pools of BFD RSs of the serving cell in the beam failure detection configuration.

[0186] In step S530, if all the BFD RSs in the set / pool of BFD RSs of the serving cell are below the threshold, or the hypothetical PDCCH BLER determined based on the measurements of the beam failure detection RSs is higher than the threshold of all the beam failure detection RSs in the set / pool of BFD RSs:

[0187] In step S535, a beam failure instance is considered to have occurred, i.e., the PHY sends a beam failure instance indication of the set / pool of BFD RSs to the MAC layer (or MAC entity).

[0188] Upon receiving the beam failure instance indication of the set / pool of BFD RSs of the serving cell from the PHY layer,

[0189] In step S540, the MAC layer starts or restarts the beamFailureDetectionTimer corresponding to the set / pool of BFD RSs of the serving cell from which the beam failure instance indication is received from the PHY. The beamFailureDetectionTimer is maintained separately for each set / pool of BFD RSs of the serving cell. The value of the beamFailureDetectionTimer is signaled by the gNB. The value of the beamFailureDetectionTimer can be the same for all sets / pools of BFD RSs of the serving cell. Alternatively, the value of the beamFailureDetectionTimer can be configured separately for each set / pool of BFD RSs of the serving cell.

[0190] In step S545, the MAC layer updates the BFI counter corresponding to the set / pool of BFD RSs of the serving cell from which the beam failure instance indication is received from the PHY layer. The BFI counter can be maintained separately for each set / pool of BFD RSs of the serving cell.

[0191] If the BFI counter >= beamFailureInstanceMaxCount for a set / pool of BFD RSs of the serving cell (in step S550), then in step S555, beam failure of the set / pool of BFD RSs of the serving cell is considered to be detected and beam failure recovery of the set / pool of BFD RSs of the serving cell is initiated. The value of the beamFailureInstanceMaxCount is signaled by the gNB. The value of the beamFailureInstanceMaxCount can be the same for all sets / pools of BFD RSs of the serving cell. Alternatively, the value of the beamFailureInstanceMaxCount can be configured separately for each set / pool of BFD RSs of the serving cell.

[0192] In step S520, if the beam failure detection configuration does not include beam failure detection RSs for multiple sets / pools of BFD RSs, the UE detects beam failure and triggers beam failure recovery as follows:

[0193] In step S560, the UE (PHY layer) can periodically measure the beam failure detection RSs of the serving cell in the beam failure detection configuration.

[0194] In step S565, if all BFD RSs of the serving cell are below the threshold, or the hypothetical PDCCH BLER determined based on the measurements of the beam failure detection RSs is higher than the threshold for all beam failure detection RSs of the serving cell:

[0195] In step S570, a beam failure instance is considered to have occurred, i.e. the PHY layer sends a beam failure instance indication to the MAC layer.

[0196] Upon receiving a beam failure instance indication of a serving cell from the PHY layer,

[0197] In step S575, the MAC layer starts or restarts the beamFailureDetectionTimer for the serving cell from which the beam failure instance indication is received from the PHY layer. One beamFailureDetectionTimer is maintained for a serving cell.

[0198] In step S580, the MAC layer updates the BFI counter (BFI_COUNTER) for the serving cell from which the beam failure instance indication is received from the PHY. One BFI counter is maintained for a serving cell.

[0199] If for a serving cell, the BFI counter >= beamFailureInstanceMaxCount (in step S585), then in step S590, a beam failure of the serving cell is considered to have been detected, and a beam failure recovery of the serving cell is initiated. The UE performs the beam failure recovery procedure for the serving cell.

[0200] Beam failure recovery procedure for an SCell supporting multiple TRPs (note that the embodiments disclosed herein for an SCell can also apply to a SpCell):

[0201] Embodiment 1:

[0202] Figure 6 and Figure 7 An enhanced format of the BFR MAC CE according to an embodiment of the disclosure is shown. Figure 6 A BFR MAC CE is shown, and the truncated BFR MAC CE with the highest ServCellIndex of the SCells of the MAC entity configured with BFD is less than 8. Figure 7 A BFR MAC CE is shown, and the truncated BFR MAC CE with the highest ServCellIndex of the SCells of the MAC entity configured with BFD is equal to or higher than 8.

[0203] In some embodiments, if one or more TRPs of an SCell meet the BFD criteria (i.e. a BFD of one or more TRPs of the SCell is detected, as previously explained), the UE:

[0204] For a TRP of an SCell for which a beam failure is detected, a BFR is triggered

[0205] -- If the UL grant is not available to transmit the BFR MAC CE or the truncated BFR MAC CE, trigger SR, or if the UL grant is available but cannot accommodate the BFR MAC CE and its subheader or the truncated BFR MAC CE and its subheader, trigger SR. If the UL grant is available and can accommodate the (truncated) BFR MAC CE and its subheader, generate and transmit the (truncated) BFR MAC CE 600, 700 in the UL grant. In an embodiment, the SR triggering, generation and transmission of the (truncated) BFR MAC CE as explained above is only performed if there is at least one SCell for which BFR is triggered and not cancelled and the evaluation of the candidate beams in the candidate beam list of the TRP for which beam failure is detected is completed. The SR configuration (PUCCH resource, SR prohibit timer, SR counter) for BFR of a TRP of a serving cell can be configured separately from the SR configuration for BFR of the serving cell.

[0206] The enhanced format of the BFR MAC CE 600, 700 is illustrated in Figure 6 and Figure 7 The BFR MAC CE 600, 700 can be generated by the UE (i.e. the MAC layer or MAC entity in the UE) as follows:

[0207] -- The BFR MAC CE 600, 700 can include a bitmap, where each bit corresponds to a serving cell. The bits corresponding to the SCells of the TRP for which beam failure is detected (and for which the evaluation of the candidate beams in the candidate beam list of the TRP for which beam failure is detected is completed) are set to 1.

[0208] -- Beam failure recovery information (e.g. candidate beam available or not available, candidate beam if available, TRP identification information, etc.) for each failed TRP of the added SCell

[0209] -- Beam failure recovery information for the TRP of the SCell for which beam failure is detected:

[0210] --- Set E to 1 or 0 to indicate whether the following is the beam failure recovery information of another TRP of the same serving cell or not, respectively. It should be noted that the E field can not be needed / included in the BFR MAC CE if only the beam failure recovery information of one TRP is included in the BFR MAC CE.

[0211] --- If there is no RS (SSB / CSI RS) with RSRP above a threshold among the candidate RSs of this TRP of the serving cell for which beam failure is detected (and recovery is initiated):

[0212] - Set AC = 0; include TRP ID, R bit. Note that in case TRP ID is not explicitly included in the beam failure detection and recovery configuration, include set ID or pool ID or list ID corresponding to different set / pool / list of BFD RS and candidate beam RS. Set 0 / pool 0 / list 0 of BFD RS corresponds to set 0 / pool 0 / list 0 of candidate beam RS, set 1 / pool 1 / list 1 of BFD RS corresponds to set 1 / pool 1 / list 1 of candidate beam RS. Set n / pool n / list n of BFD RS corresponds to set n / pool n / list n of candidate beam RS.

[0213] - Else:

[0214] - Set AC = 1; include candidate RS ID, i.e., ID of SSB / CSI RS of TRP whose SS-RSRP / CSI-RSRP is above threshold.

[0215] - In an embodiment, candidate RS ID can be index of entry in candidate RS list corresponding to SSB / CSI RS of TRP whose SS-RSRP / CSI-RSRP is above threshold. If the list is common to all TRPs, TRP can be identified implicitly. If candidate beam RS list is different for different TRPs, entries in multiple candidate beam RS lists can be indexed in order starting from first list. In an embodiment, in addition to candidate RS ID, TRP ID can also be included. Note that in case TRP ID is not explicitly included in the beam failure detection and recovery configuration, include set ID or pool ID or list ID corresponding to different set of BFD RS and candidate beam RS. Set 0 / pool 0 / list 0 of BFD RS corresponds to set 0 / pool 0 / list 0 of candidate beam RS, set 1 / pool 1 / list 1 of BFD RS corresponds to set 1 / pool 1 / list 1 of candidate beam RS. Set n / pool n / list n of BFD RS corresponds to set n / pool n / list n of candidate beam RS. Bitmap field in BFR MAC CE 600, 700 is defined as follows:

[0216] - SP: This field indicates beam failure detection of SpCell of this MAC entity. SP field is set to 1 to indicate that beam failure is detected for SpCell. Otherwise, set to 0;

[0217] - C i (BFR MAC CE): This field indicates beam failure detection and presence of octet containing AC field for SCell with ServCellIndex i. C iThe field indicates that beam failure is detected and the evaluation of candidate beams in the candidate beam list of the TRP where beam failure is detected is completed, and the SCell with ServCellIndex i does not have the octet containing the AC field. The number of octets containing the AC field is maximized without exceeding the available grant size; i The field indicates that beam failure is not detected (or the evaluation of candidate beams in the candidate beam list of the TRP where beam failure is detected is not completed), and the SCell with ServCellIndex i does not have the octet containing the AC field. The octets containing the AC field are included in ascending order of ServCellIndex (if any). The number of octets containing the AC field is maximized without exceeding the available grant size;

[0218] -C i The field indicates that beam failure is detected and the evaluation of candidate beams in the candidate beam list of the TRP where beam failure is detected is completed, and the SCell with ServCellIndex i does not have the octet containing the AC field. The number of octets containing the AC field is maximized without exceeding the available grant size; i The field indicates that beam failure is detected and the evaluation of candidate beams in the candidate beam list of the TRP where beam failure is detected is completed, and the SCell with ServCellIndex i does not have the octet containing the AC field. The number of octets containing the AC field is maximized without exceeding the available grant size; i The field indicates that beam failure is not detected (or the evaluation of candidate beams in the candidate beam list of the TRP where beam failure is detected is not completed), and the SCell with ServCellIndex i does not have the octet containing the AC field. The octets containing the AC field are included in ascending order of ServCellIndex (if any). The number of octets containing the AC field is maximized without exceeding the available grant size;

[0219] In an embodiment, if the SCell is deactivated and the SCell is configured with multiple sets / pools of BFD RSs (in the active DL BWP), the UE sets the BFI counter corresponding to each set / pool of BFD RSs or to each TRP to zero; and cancels all triggered BFRs for the set / pool of BFD RSs or the TRP of this serving cell.

[0220] In an embodiment, for a serving cell, if the HARQ process for the transmission of the BFR MAC CE or the truncated BFR MAC CE containing the beam failure recovery information for the set / pool of BFD RSs or the TRP of this serving cell receives a PDCCH addressed to the C-RNTI indicating a new transmission of an uplink grant, the UE sets the BFI counter corresponding to the set / pool of BFD RSs or the TRP to zero and cancels all triggered BFRs for the set / pool of BFD RSs or the TRP of this serving cell.

[0221] In an embodiment, when a MAC PDU is transmitted and this PDU includes a BFR MAC CE or a truncated BFR MAC CE containing beam failure information of the set / pool of BFD RSs of a SCell or of a TRP, all BFR triggered for the set / pool of BFD RSs of the SCell or for the TRP can be cancelled. In an embodiment, for each pending SR not triggered according to a BSR procedure of a serving cell, the MAC entity can:

[0222] If this SR is triggered by a beam failure recovery of the set / pool of BFD RSs of the serving cell (or of a SCell) and a MAC PDU is transmitted and this PDU includes a BFR MAC CE or a truncated BFR MAC CE containing beam failure recovery information of the set / pool of BFD RSs of the serving cell (or of the SCell) or if this SR is triggered by a beam failure recovery of the set / pool of BFD RSs of a SCell and this SCell is deactivated: cancel the pending SR and stop the corresponding sr-ProhibitTimer (if running).

[0223] It should be noted that a beam failure recovery of the set / pool of BFD RSs of a serving cell can also be referred to as an M-TRP BFR of the serving cell or a partial BFR of the serving cell or an enhanced BFR of the serving cell.

[0224] Embodiment 1A:

[0225] Figure 8 and Figure 9 An enhanced format of a BFR MAC CE according to an embodiment of the disclosure is shown. Figure 8 A BFR is shown and the truncated BFR MAC CE of the SCell with the highest ServCellIndex configured with BFD of the MAC entity is less than 8. In addition, Figure 9 A BFR is shown and the truncated BFR MAC CE of the SCell with the highest ServCellIndex configured with BFD of the MAC entity is equal to or higher than 8.

[0226] In some embodiments, if one or more set / pool of BFD RSs of a SCell meets the BFD criteria (i.e. a beam failure of one or more set / pool of BFD RSs of the SCell is detected, as previously explained), the UE:

[0227] For one or more set / pool of BFD RSs of a SCell for which a beam failure is detected, a BFR is triggered,

[0228] -- If UL grant is not available to transmit BFR MAC CE or truncated BFR MAC CE, trigger SR, or if UL grant is available but cannot accommodate BFR MAC CE and its subheader or truncated BFR MAC CE and its subheader, trigger SR. If UL grant is available and can accommodate (truncated) BFR MAC CE and its subheader. If UL grant is available and can accommodate (truncated) BFR MAC CE and its subheader, transmit (truncated) BFR MAC CE 800, 900 in the UL grant. In an embodiment, the SR triggering and the generation and transmission of BFR MAC CE as explained above are performed only if there is at least one SCell for which BFR is triggered and not cancelled and the evaluation of candidate beams in the candidate beam list corresponding to the set / pool of BFD RS for which beam failure is detected is completed. The SR configuration (PUCCH resource, SR prohibit timer, SR counter) for BFR of the set / pool of BFD RS of a serving cell can be configured separately from the SR configuration for BFR of the serving cell.

[0229] The enhanced format of BFR MAC CE 800, 900 is illustrated in Figure 8 and Figure 9 The BFR MAC CE 800, 900 is generated by the UE (i.e., MAC layer or MAC entity in the UE) as follows:

[0230] -- BFR MAC CE 800, 900 includes a bitmap, where each bit corresponds to a serving cell. The bits corresponding to the SCells of the set / pool of BFD RS for which beam failure is detected (and for which the evaluation of candidate beams in the candidate beam list corresponding to the set / pool of BFD RS for which beam failure is detected is completed) are set to 1.

[0231] -- Beam failure recovery information for each set / pool of BFD RS for which beam failure is detected (i.e., one AC octet for each set / pool of BFD RS) is added

[0232] -- For the beam failure recovery information for a set / pool of BFD RS:

[0233] --- E is set to 1 or 0 to indicate whether the following is the beam failure recovery information for another set / pool of BFD RS of the same serving cell or not, respectively. It should be noted that if only the beam failure recovery information for one TRP needs to be included in the BFR MAC CE, the E field can not be needed / included in the BFR MAC CE.

[0234] --- If there is no RS (SSB / CSI RS) with RSRP above the threshold among the candidate RSs of the set / pool of candidate RSs corresponding to the set / pool of BFD RSs of the serving cell where beam failure is detected:

[0235] - Set AC = 0; include set / pool ID, R bits.

[0236] --- Else:

[0237] - Set AC = 1; include candidate RS ID, i.e., ID of SSB / CSI RS with SS-RSRP / CSI-RSRP above the threshold among the candidate RSs of the set / pool of candidate RSs corresponding to the set / pool of BFD RSs of the serving cell where beam failure is detected

[0238] - In an embodiment, the candidate RS ID can be an index of an entry in the list of candidate beam RSs corresponding to the SSB / CSI RS. If there are multiple lists of candidate beam RSs, the entries in the multiple lists of candidate beam RSs can be indexed in order starting from the first list. In an embodiment, in addition to the candidate RS ID, the set / pool ID can also be included. In an embodiment, in addition to the candidate RS ID, the set / pool ID can also be included. Set 0 / pool 0 / list 0 of BFD RSs corresponds to set 0 / pool 0 / list 0 of candidate beam RSs, set 1 / pool 1 / list 1 of BFD RSs corresponds to set 1 / pool 1 / list 1 of candidate beam RSs. Set n / pool n / list n of BFD RSs corresponds to set n / pool n / list n of candidate beam RSs.

[0239] The bitmap field in the BFR MAC CE 800, 900 is defined as follows:

[0240] - SP: This field indicates beam failure detection of the SpCell of this MAC entity. The SP field is set to 1 to indicate that beam failure is detected for the SpCell. Otherwise, it is set to 0;

[0241] - C i The C field set to 1 indicates that beam failure is detected and the evaluation of the candidate beams in the list of candidate beams corresponding to the set / pool of BFD RSs where beam failure is detected is completed, and the SCell with ServCellIndex i exists the octet containing the AC field. The C field set to 0 indicates that beam failure is not detected and the evaluation of the candidate beams in the list of candidate beams corresponding to the set / pool of BFD RSs where beam failure is detected is not completed, and the SCell with ServCellIndex i does not exist the octet containing the AC field. i The C field set to 1 indicates that beam failure is detected and the evaluation of the candidate beams in the list of candidate beams corresponding to the set / pool of BFD RSs where beam failure is detected is completed, and the SCell with ServCellIndex i exists the octet containing the AC field. The C field set to 0 indicates that beam failure is not detected and the evaluation of the candidate beams in the list of candidate beams corresponding to the set / pool of BFD RSs where beam failure is detected is not completed, and the SCell with ServCellIndex i does not exist the octet containing the AC field. iThe field indicates that no beam failure is detected (or the evaluation of candidate beams in the list of candidate beams corresponding to the set / pool of BFD RSs for which beam failure is detected is not completed), and the SCell with ServCellIndex i does not have an octet containing the AC field. The octets containing the AC field are included in ascending order of ServCellIndex (if any);

[0242] - C i (truncated BFR MAC CE): This field indicates the beam failure detection for the SCell with ServCellIndex i. C i The field indicates that beam failure is detected and the evaluation of candidate beams in the list of candidate beams corresponding to the set / pool of BFD RSs for which beam failure is detected is completed, and there can be an octet containing the AC field for the SCell with ServCellIndex i. C i The field indicates that no beam failure is detected (or the evaluation of candidate beams in the list of candidate beams corresponding to the set / pool of BFD RSs for which beam failure is detected is not completed), and the SCell with ServCellIndex i does not have an octet containing the AC field. The octets containing the AC field are included in ascending order of ServCellIndex (if any); the number of included octets containing the AC field is maximized without exceeding the available grant size;

[0243] In an embodiment, if the SCell is deactivated and the SCell is configured with multiple sets / pools of BFD RSs (in the active DL BWP), the UE sets the BFI counter corresponding to each set / pool of BFD RSs or to each TRP to zero; and cancels all triggered BFRs for the sets / pools of BFD RSs or TRPs of this serving cell.

[0244] In an embodiment, for a serving cell, if a PDCCH addressed to C-RNTI indicating an uplink grant for a new transmission is received for the HARQ process of the transmission of the BFR MAC CE or the truncated BFR MAC CE containing the beam failure recovery information for the sets / pools of BFD RSs or TRPs of this serving cell, the UE sets the BFI counter corresponding to the sets / pools of BFD RSs or TRPs to zero and cancels all triggered BFRs for the sets / pools of BFD RSs or TRPs of this serving cell.

[0245] In an embodiment, when a MAC PDU is transmitted and this PDU includes a BFR MAC CE or a truncated BFR MAC CE containing beam failure information of the set / pool of BFD RSs or TRP of the SCell, all BFRs triggered for the set / pool of BFD RSs or TRP of the SCell can be cancelled.

[0246] In an embodiment, for each pending SR not triggered according to a BSR procedure of the serving cell, the MAC entity can:

[0247] If this SR is triggered by a beam failure recovery of the set / pool of BFD RSs or TRP of the serving cell (or SCell) and a MAC PDU is transmitted and this PDU includes a BFR MAC CE or a truncated BFR MAC CE containing beam failure recovery information of the set / pool of BFD RSs or TRP of the serving cell (or SCell); or if this SR is triggered by a beam failure recovery of the set / pool of BFD RSs or TRP of the SCell and this SCell is deactivated: cancel the pending SR and stop the corresponding sr-ProhibitTimer (if running).

[0248] It should be noted that the beam failure recovery of the set / pool of BFD RSs or TRP of the serving cell can also be referred to as M-TRP BFR of the serving cell or partial BFR of the serving cell or enhanced BFR of the serving cell.

[0249] Embodiment 2:

[0250] Figure 10 And Figure 11 An enhanced format of the BFR MAC CE according to an embodiment of the disclosure is shown. Figure 10 A BFR is shown and the truncated BFR MAC CE with the highest ServCellIndex of the SCell configured with BFD of the MAC entity is less than 8. In addition, Figure 11 A BFR is shown and the truncated BFR MAC CE with the highest ServCellIndex of the SCell configured with BFD of the MAC entity is equal to or higher than 8.

[0251] In some embodiments, if the TRP of the SCell meets the BFD criteria (i.e. detects a beam failure of the TRP of the SCell and initiates recovery, as previously explained), the UE:

[0252] - triggers a BFR for the TRP of the SCell

[0253] - If the UL grant is not available to transmit the BFR MAC CE or the truncated BFR MAC CE, an SR is triggered, or if the UL grant is available but cannot accommodate the BFR MAC CE and its subheader or the truncated BFR MAC CE and its subheader, an SR is triggered. If the UL grant is available and can accommodate the (truncated) BFR MAC CE and its subheader, - the BFR MAC CE 1000, 1100 is transmitted in the UL grant.

[0254] In an embodiment, the SR triggering and the generation and transmission of the BFR MAC CE as explained above are only performed if there is at least one SCell for which BFR is triggered and not cancelled and the evaluation of the candidate beams in the candidate beam list for the TRP for which beam failure is detected is completed. The SR configuration (PUCCH resource, SR prohibit timer, SR counter) for BFR of a TRP of a serving cell can be configured separately from the SR configuration for BFR of the serving cell.

[0255] The enhanced format of the BFR MAC CE 1000, 1100 is illustrated in Figure 10 and Figure 11 The BFR MAC CE 1000, 1100 is generated by the UE (i.e. the MAC layer), as follows:

[0256] - The BFR MAC CE 1000, 1100 includes a bitmap, where each bit corresponds to a serving cell. The bits corresponding to the SCells of the TRP for which beam failure is detected are set to 1.

[0257] - It indicates that the BFR is for the TRP of the serving cell (T = 1 is set)

[0258] - If there is no RS (SSB / CSI RS) with RSRP above a threshold among the RSs of the TRP of the SCell that initiated the beam failure recovery, it is indicated in the BFR MAC CE which TRP failed. (AC = 0, T = 1, TRP ID, R bit)

[0259] - Otherwise, the candidate RS IDs of the TRP are included in the BFR MAC CE. (AC = 1, T = 1, candidate RS IDs)

[0260] - The candidate RS ID is the index of the entry in the list of candidate RSs corresponding to the SSB / CSI RS of the TRP whose SS-RSRP / CSI-RSRP is above the threshold. The TRP can be implicitly identified because the list is common to all TRPs. If the list of candidate beam RSs is different for different TRPs, the entries in the multiple lists of candidate beam RSs can be indexed sequentially starting from the first list. In an embodiment, in addition to the candidate RS ID, the TRP ID is also included (i.e. AC = 1, T = 1, candidate RS ID, TRP ID).

[0261] In alternative embodiments, the BFR MAC CE includes:

[0262] - A bitmap where each bit corresponds to a serving cell and the bit corresponding to the serving cell of the TRP where the beam failure was detected is set to 1.

[0263] - If there is at least one RS (SSB / CSI RS) with RSRP above the threshold among the candidate beam RSs of the set or pool of SCells where the beam failure was detected and recovery was initiated, it is AC = 1, candidate RS ID, TRP ID, zero or more R bits.

[0264] - If there is no RS (SSB / CSI RS) with RSRP above the threshold among the candidate beam RSs of the set or pool of SCells where the beam failure was detected and recovery was initiated, it is AC = 0, TRP ID and zero or more R bits.

[0265] - Including in the MAC subheader of the BFR MAC CE a reserved LCID, where the reserved LCID is the BFR MAC CE for the BFR of the TRP of the serving cell. This LCID is different from the LCID included in the MAC subheader of the BFR MAC CE for the BFR of the serving cell.

[0266] - In some embodiments, if all the TRPs of the SCell meet the BFR criteria, the UE:

[0267] - triggers a BFR for the beam failure recovery of that SCell.

[0268] - triggers an SR if an UL grant is not available to transmit the BFR MAC CE or the truncated BFR MAC CE, or if an UL grant is available but cannot accommodate the BFR MAC CE and its header or the truncated BFR MAC CE and its subheader. If an UL grant is available and can accommodate the (truncated) BFR MAC CE and its header,

[0269] -- Transmit the BFR MAC CE 1000, 1100 in the UL grant. In an embodiment, the SR triggering as explained above and the generation and transmission of the BFR MAC CE are only performed if there is at least one SCell for which BFR is triggered and not cancelled and the evaluation of the candidate beams in the candidate beam list for the TRP for which beam failure was detected is completed.

[0270] The enhanced format of the BFR MAC CE 1000, 1100 is illustrated in Figure 10 and Figure 11 The BFR MAC CE 1000, 1100 is generated by the UE (i.e. the MAC layer) as follows:

[0271] --- The BFR MAC CE 1000, 1100 includes a bitmap where each bit corresponds to a serving cell. The bit corresponding to the SCell for which beam failure was detected is set to 1.

[0272] --- Indicate that the BFR is not for a TRP (set T = 0), i.e. it is for a serving cell

[0273] --- If there is no RS (SSB / CSI RS) in the list of candidate beam RSs of the SCell for which beam failure recovery was initiated for which the RSRP is above a threshold

[0274] --- AC = 0, T = 0, R bit. In an embodiment, T can be the R bit set to 0.

[0275] --- Else include the RS ID in the BFR MAC CE 1000, 1100

[0276] --- AC = 1, T = 0, candidate RS ID. In an embodiment, T can be the R bit set to 0.

[0277] The bitmap field in the BFR MAC CE 1000, 1100 is defined as follows:

[0278] - SP: This field indicates the beam failure detection of the SpCell of this MAC entity. The SP field is set to 1 to indicate that beam failure was detected for the SpCell. Otherwise, it is set to 0;

[0279] - C i (BFR MAC CE): This field indicates the beam failure detection and the presence of the octet containing the AC field for the SCell with ServCellIndex i. The C iThe field indicates that beam failure is detected and the evaluation of candidate beams in the candidate beam list of the TRP where beam failure is detected is completed, and the SCell with ServCellIndex i does not have the octet containing the AC field. The octet containing the AC field is included based on ascending order of ServCellIndex (if present). The number of octets containing the AC field that are included is maximized without exceeding the available grant size. i The field indicates that beam failure is not detected (or the evaluation of candidate beams in the candidate beam list of the TRP where beam failure is detected is not completed), and the SCell with ServCellIndex i does not have the octet containing the AC field. The octet containing the AC field is included based on ascending order of ServCellIndex (if present). The number of octets containing the AC field that are included is maximized without exceeding the available grant size.

[0280] -C i The field indicates that beam failure is detected and the evaluation of candidate beams in the candidate beam list of the TRP where beam failure is detected is completed, and the SCell with ServCellIndex i does not have the octet containing the AC field. The octet containing the AC field is included based on ascending order of ServCellIndex (if present). The number of octets containing the AC field that are included is maximized without exceeding the available grant size. i The field indicates that beam failure is detected and the evaluation of candidate beams in the candidate beam list of the TRP where beam failure is detected is completed, and the SCell with ServCellIndex i does not have the octet containing the AC field. The octet containing the AC field is included based on ascending order of ServCellIndex (if present). The number of octets containing the AC field that are included is maximized without exceeding the available grant size. i The field indicates that beam failure is not detected (or the evaluation of candidate beams in the candidate beam list of the TRP where beam failure is detected is not completed), and the SCell with ServCellIndex i does not have the octet containing the AC field. The octet containing the AC field is included based on ascending order of ServCellIndex (if present). The number of octets containing the AC field that are included is maximized without exceeding the available grant size.

[0281] In an embodiment, if an SCell is deactivated and the SCell is configured with multiple sets / pools of BFD RSs (in the active DL BWP), the UE sets the BFI counter corresponding to each set / pool of BFD RSs or to each TRP to zero; and cancels all triggered BFRs for the set / pool of BFD RSs or the TRP of this serving cell.

[0282] In an embodiment, for a serving cell, if a HARQ process for the transmission of the BFR MAC CE or the truncated BFR MAC CE for beam failure recovery information containing the set / pool of BFD RSs or the TRP of this serving cell receives a PDCCH addressed to the C-RNTI indicating a new transmission of an uplink grant, the UE sets the BFI counter corresponding to the set / pool of BFD RSs or the TRP to zero and cancels all triggered BFRs for the set / pool of BFD RSs or the TRP of this serving cell.

[0283] In an embodiment, when a MAC PDU is transmitted and this PDU includes a BFR MAC CE or a truncated BFR MAC CE containing beam failure information of the set / pool of BFD RSs of the SCell or of the TRP, all BFRs triggered for the set / pool of BFD RSs of the SCell or for the TRP can be cancelled.

[0284] In an embodiment, for each pending SR not triggered according to a BSR procedure of the serving cell, the MAC entity can:

[0285] If this SR is triggered by a beam failure recovery of the set / pool of BFD RSs of the serving cell (or of the SCell) and a MAC PDU is transmitted and this PDU includes a BFR MAC CE or a truncated BFR MAC CE containing beam failure recovery information of the set / pool of BFD RSs of the serving cell (or of the SCell) or of the TRP; or if this SR is triggered by a beam failure recovery of the set / pool of BFD RSs of the SCell and this SCell is deactivated: cancel the pending SR and stop the corresponding sr-ProhibitTimer (if running).

[0286] It should be noted that the beam failure recovery of the set / pool of BFD RSs of the serving cell or of the TRP can also be referred to as M-TRP BFR of the serving cell or partial BFR of the serving cell or enhanced BFR of the serving cell.

[0287] Embodiment 2A:

[0288] Figure 12 and Figure 13 An enhanced format of the BFR MAC CE according to an embodiment of the disclosure is shown. Figure 12 A BFR is shown and the truncated BFR MAC CE with the highest ServCellIndex of the SCell(s) configured with BFD of this MAC entity is less than 8. In addition, Figure 13 A BFR is shown and the truncated BFR MAC CE with the highest ServCellIndex of the SCell(s) configured with BFD of this MAC entity is equal to or higher than 8.

[0289] In some embodiments, if the set / pool of BFD RSs of the SCell fulfils the BFD criteria (i.e. based on a BFD RS of the set / pool of BFD RSs of the SCell detecting a beam failure and initiating recovery as previously explained), the UE:

[0290] - triggers a BFR for the set / pool of BFD RSs of the SCell;

[0291] - if the UL grant is not available to transmit the BFR MAC CE or the truncated BFR MAC CE, trigger SR, or if the UL grant is available but cannot accommodate the BFR MAC CE and its header or the truncated BFR MAC CE and its subheader, trigger SR. If the UL grant is available and can accommodate the (truncated) BFR MAC CE and its header; and

[0292] -- Transmit the BFR MAC CE 1200, 1300 in the UL grant. In an embodiment, the SR triggering as explained above and the generation and transmission of the BFR MAC CE are performed only if there is at least one SCell for which BFR is triggered and not cancelled and the evaluation of the candidate beams in the candidate beam list corresponding to the set / pool of BFD RS for which beam failure is detected is completed. The SR configuration (PUCCH resource, SR prohibit timer, SR counter) for BFR of the set / pool of BFD RS of the serving cell can be configured separately from the SR configuration for BFR of the serving cell.

[0293] The enhanced format of the BFR MAC CE 1200, 1300 is illustrated in Figure 12 and Figure 13 The BFR MAC CE 1200, 1300 is generated by the UE (i.e. MAC layer) as follows:

[0294] --- The BFR MAC CE 1200, 1300 includes a bitmap where each bit corresponds to a serving cell. The bit corresponding to the SCell for which beam failure is detected is set to 1.

[0295] --- Indicate the set / pool of BFD RS among the multiple sets / pools of BFD RS for which the BFD RS detects beam failure (T = 1 is set).

[0296] --- If there is no RS (SSB / CSI RS) with RSRP above a threshold among the candidate beam RS of the set / pool of SCells for which beam failure is detected and recovery is initiated, indicate the set / pool of BFD RS for which beam failure is detected in the BFR MAC CE. (AC = 0, T = 1, set / pool ID, R bit).

[0297] --- Otherwise, include the candidate RS ID corresponding to this set / pool in the BFR MAC CE. (AC = 1, T = 1, candidate RS ID).

[0298] - Candidate RS ID is the index of the entry in the list of candidate RSs corresponding to SSB / CSI RS of the set / pool of SS-RSRP / CSI-RSRP above a threshold. If the list is common to all sets / pools, the set / pool can be identified implicitly. In embodiments, the set / pool ID is also included.

[0299] In alternative embodiments, the BFR MAC CE comprises:

[0300] - a bitmap, where each bit corresponds to a serving cell, the bit corresponding to the serving cell where the beam failure is detected is set to 1.

[0301] If there is at least one RS (SSB / CSI RS) with RSRP above a threshold among the candidate beam RSs of the set or pool of SCells where the beam failure is detected and recovery is initiated, it is AC = 1, candidate RS ID, set / pool ID, zero or more R bits.

[0302] - If there is no RS (SSB / CSI RS) with RSRP above a threshold among the candidate beam RSs of the set or pool of SCells where the beam failure is detected and recovery is initiated, it is AC = 0, set / pool ID and zero or more R bits.

[0303] - including a reserved LCID in the MAC subheader of the BFR MAC CE, where the reserved LCID is the BFR MAC CE for the BFR of the set / pool of serving cells. This LCID is different from the LCID included in the MAC subheader of the BFR MAC CE for the BFR of a serving cell.

[0304] - In some embodiments, if all sets / pools of BFD RSs of a SCell meet the BFR criteria:

[0305] - a SCell BFR is triggered for that SCell.

[0306] - if an UL grant is not available to transmit the BFR MAC CE or the truncated BFR MAC CE, an SR is triggered, or if an UL grant is available but cannot accommodate the BFR MAC CE and its header or the truncated BFR MAC CE and its subheader, an SR is triggered. If an UL grant is available and can accommodate the (truncated) BFR MAC CE and its header,

[0307] - the BFR MAC CE 1200, 1300 is transmitted in the UL grant.

[0308] In an embodiment, the SR triggering as explained above and the generation and transmission of the BFR MAC CE are performed only if there is at least one SCell for which BFR is triggered and not cancelled and the evaluation of the candidate beams in the candidate beam list corresponding to the set / pool of BFD RS for which beam failure is detected is completed.

[0309] The enhanced format of the BFR MAC CE 1200, 1300 is illustrated in Figure 12 and Figure 13 The BFR MAC CE 1200, 1300 is generated by the UE (i.e. MAC layer) as follows:

[0310] - The BFR MAC CE 1200, 1300 includes a bitmap where each bit corresponds to a serving cell. The bit corresponding to the SCell for which beam failure is detected is set to 1.

[0311] - Indicating that the BFR is not for a specific set / pool (T = 0 is set).

[0312] - If there is no RS (SSB / CSI RS) with RSRP above a threshold among the RS in the candidate beam RS list of the SCell initiating beam failure recovery.

[0313] - AC = 0, T = 0, R bit. In an embodiment, T can be an R bit set to 0.

[0314] - Else, the RS ID is included in the BFR MAC CE 1200, 1300.

[0315] - AC = 1, T = 0, candidate RS ID. In an embodiment, T can be an R bit set to 0.

[0316] The bitmap field in the BFR MAC CE 1200, 1300 is defined as follows:

[0317] - SP: This field indicates the beam failure detection of the SpCell of this MAC entity. The SP field is set to 1 to indicate that beam failure is detected for the SpCell. Otherwise, it is set to 0;

[0318] - C i (BFR MAC CE): This field indicates the beam failure detection and the presence of the octet containing the AC field for the SCell with ServCellIndex i. C iThe field indicates that beam failure is detected and the evaluation of candidate beams in the candidate beam list corresponding to the set / pool of BFD RSs for which beam failure is detected is completed, and the SCell with ServCellIndex i does not have an octet containing the AC field. The number of octets containing the AC field included is maximized without exceeding the available grant size. i The field indicates that beam failure is not detected (or the evaluation of candidate beams in the candidate beam list corresponding to the set / pool of BFD RSs for which beam failure is detected is not completed), and the SCell with ServCellIndex i does not have an octet containing the AC field. The octet containing the AC field is included based on ServCellIndex in ascending order;

[0319] -C i The field indicates that beam failure is detected and the evaluation of candidate beams in the candidate beam list corresponding to the set / pool of BFD RSs for which beam failure is detected is completed, and the SCell with ServCellIndex i does not have an octet containing the AC field. The number of octets containing the AC field included is maximized without exceeding the available grant size. i The field indicates that beam failure is detected and the evaluation of candidate beams in the candidate beam list corresponding to the set / pool of BFD RSs for which beam failure is detected is completed, and the SCell with ServCellIndex i does not have an octet containing the AC field. The number of octets containing the AC field included is maximized without exceeding the available grant size. i The field indicates that beam failure is not detected (or the evaluation of candidate beams in the candidate beam list corresponding to the set / pool of BFD RSs for which beam failure is detected is not completed), and the SCell with ServCellIndex i does not have an octet containing the AC field. The octet containing the AC field is included based on ServCellIndex in ascending order; the number of octets containing the AC field included is maximized without exceeding the available grant size.

[0320] In an embodiment, if the SCell is deactivated and the SCell is configured with multiple sets / pools of BFD RSs (in the active DL BWP), the UE sets the BFI counter corresponding to each set / pool of BFD RSs or corresponding to each TRP to zero; and cancels all triggered BFR for this serving cell for the set / pool of BFD RSs or TRP.

[0321] In an embodiment, for a serving cell, if a HARQ process for transmission of a BFR MAC CE or truncated BFR MAC CE for beam failure recovery information of a set / pool of BFD RSs or TRP containing this serving cell receives a PDCCH addressed to C-RNTI indicating a new transmission of uplink grant, the UE sets the BFI counter corresponding to the set / pool of BFD RSs or TRP to zero and cancels all triggered BFR for the set / pool of BFD RSs or TRP of this serving cell.

[0322] In an embodiment, when a MAC PDU is transmitted and this PDU includes a BFR MAC CE or truncated BFR MAC CE containing beam failure information of a set / pool of BFD RSs or TRP of a SCell, all BFR triggered for the set / pool of BFD RSs or TRP of the SCell can be cancelled.

[0323] In an embodiment, for each pending SR not triggered according to a BSR procedure of a serving cell, the MAC entity can: if this SR is triggered by a beam failure recovery of a set / pool of BFD RSs or TRP of the serving cell (or a SCell) and a MAC PDU is transmitted and this PDU includes a BFR MAC CE or truncated BFR MAC CE containing beam failure recovery information of a set / pool of BFD RSs or TRP of the serving cell (or a SCell); or if this SR is triggered by a beam failure recovery of a set / pool of BFD RSs or TRP of a SCell and this SCell is deactivated: cancel the pending SR and stop the corresponding sr-ProhibitTimer, if running.

[0324] It should be noted that the beam failure recovery of a set / pool of BFD RSs or TRP of a serving cell can also be referred to as M-TRP BFR of a serving cell or partial BFR of a serving cell or enhanced BFR of a serving cell.

[0325] Beam failure recovery procedure for SpCell supporting multiple TRPs:

[0326] Embodiment 1:

[0327] In some embodiments, if a beam failure of a TRP of a SpCell is detected, as previously explained, the UE initiates a beam failure recovery of the TRP of the SpCell.

[0328] - Triggering a random access on the SpCell.

[0329] --- If there is at least one RS (SSB / CSI RS) with RSRP above a threshold among the candidate beam RSs associated with the TRP of the SpCell that initiated the beam failure recovery, CFRA is performed.

[0330] -- Otherwise, the UE:

[0331] --- CBRA is performed.

[0332] --- A BFR MAC CE is generated. The BFR MAC CE includes a bitmap where each bit corresponds to a serving cell. The bit corresponding to the SpCell is set to 1.

[0333] --- In the BFR MAC CE, which TRP of the SpCell failed is indicated. For example, the format of the BFR MAC CE 600, 700 shown in Figure 6 and Figure 7 and other formats as explained in Embodiment 1 of the beam failure recovery procedure for SCells supporting multiple TRPs can be used. The TRP ID of the TRP for which beam failure was detected is included in the BFR MAC CE.

[0334] - In some embodiments, otherwise, if beam failure of all TRPs of the SpCell is detected, as previously explained, the UE initiates beam failure recovery of the SpCell:

[0335] -- Random access is triggered on the SpCell.

[0336] --- If there is at least one RS (SSB / CSI RS) with RSRP above a threshold among the RSs in the list of candidate beam RSs of the SpCell, CFRA is performed.

[0337] -- Otherwise, the UE:

[0338] --- CBRA is performed.

[0339] --- A BFR MAC CE is generated.

[0340] ---- The BFR MAC CE includes a bitmap where each bit corresponds to a serving cell. The bit (SP bit) corresponding to the SpCell is set to 1.

[0341] ---- In embodiments, beam failure recovery information for the SpCell is not included.

[0342] ---- In alternative embodiments, beam failure recovery information for the failed TRP can be included. For example, the format of the BFR MAC CE 600, 700 shown in Figure 6 and Figure 7The format of the illustrated BFR MAC CE 600, 700 is used to indicate the beam failure recovery information. The BFR MAC CE can be transmitted in a similar way as the BFR MAC CE Figure 6 and Figure 7 The individual fields are set in a similar way as for the case of SCell BFR.

[0343] It should be noted that the beam failure recovery of a set / pool of BFD RSs of a serving cell or a TRP can also be referred to as M-TRP BFR of a serving cell or partial BFR of a serving cell or enhanced BFR of a serving cell.

[0344] Embodiment 1A:

[0345] In some embodiments, if a beam failure of a set / pool of BFD RSs of the SpCell is detected, as explained previously, the UE initiates a beam failure recovery of the set / pool of BFD RSs:

[0346] - triggering a random access on the SpCell.

[0347] - performing CFRA if there is at least one RS (SSB / CSI RS) with RSRP above a threshold among the candidate beam RSs corresponding to the set / pool of BFD RSs of the SpCell on which the beam failure recovery is initiated.

[0348] - Otherwise, the UE:

[0349] - performs CBRA.

[0350] - generates a BFR MAC CE. The BFR MAC CE includes a bitmap where each bit corresponds to a serving cell. The bit corresponding to the SpCell (SP bit) is set to 1.

[0351] - indicates in the BFR MAC CE the set / pool of BFD RSs based on which the beam failure was detected. For example, the format of the BFR MAC CE 800, 900 illustrated Figure 8 and Figure 9 and other formats as explained in Embodiment 1A of the beam failure recovery procedure for SCells supporting multiple TRPs. The set / pool ID of the set of BFD RSs for which the beam failure was detected is included in the BFR MAC CE.

[0352] In some embodiments, otherwise, if a beam failure of all sets / pools of BFD RSs of the SpCell is detected, as explained previously, the UE initiates a beam failure recovery of the SpCell:

[0353] - triggering a random access on the SpCell.

[0354] ---If there is at least one RS (SSB / CSI RS) in the candidate beam RS list of SpCell with an RSRP higher than the threshold, then CFRA is performed.

[0355] --otherwise

[0356] ---Execute CBRA.

[0357] ---Generate BFR MAC CE.

[0358] The BFR MAC CE includes a bitmap, where each bit corresponds to the serving cell. The bit corresponding to the SpCell (SP bit) is set to 1.

[0359] ----In this embodiment, beam fault recovery information for SpCell is not included.

[0360] In an alternative embodiment, beam fault recovery information may be included for the failed TRP (i.e., the set / pool / list of BFD RSs that detected beam faults). For example, beam fault recovery information may be used. Figure 8 and Figure 9 The formats shown are those of BFR MAC CE 800 and 900, as well as other formats explained in Example 1A of the beam fault recovery process for SCells supporting multiple TRPs, to indicate beam fault recovery information. This can be done in conjunction with... Figure 8 and Figure 9 The fields are set in a similar manner to those used for SCell BFR.

[0361] It should be noted that beam fault recovery of the serving cell's BFD RS pool or TRP can also be referred to as the serving cell's M-TRP BFR, the serving cell's partial BFR, or the serving cell's enhanced BFR.

[0362] Example 2:

[0363] - In some embodiments, if a beam fault is detected in the TRP of the SpCell, as previously explained, then the UE:

[0364] --Trigger BFR for TRP of SCell.

[0365] - An SR is triggered if the UL license is not available for transmitting a BFR MAC CE or a truncated BFR MAC CE, or if the UL license is available but cannot contain a BFR MAC CE and its sub-headers or a truncated BFR MAC CE and its sub-headers.

[0366] -- If UL grant is available and can accommodate (truncated) BFR MAC CE and its subheader, transmit (truncated) BFR MAC CE in the UL grant.

[0367] In an embodiment, the SR triggering and the generation and transmission of the BFR MAC CE as explained above are only performed if there is at least one serving where BFR is triggered and not cancelled and the evaluation of the candidate beams in the candidate beam list of the TRP where the beam failure is detected is completed.

[0368] The enhanced format of the BFR MAC CE 1000, 1100 is illustrated in Figure 10 and Figure 11 The BFR MAC CE is generated as follows:

[0369] --- indicates that the BFR is for a TRP (set T = 1).

[0370] --- If there is no RS (SSB / CSI RS) with RSRP above a threshold among the RSs of the TRP of the SPCell where the beam failure recovery is initiated, indicate which TRP failed in the BFR MAC CE. (AC = 0, T = 1, TRP ID, R bit).

[0371] --- Else: include the RS ID of the TRP in the BFR MAC CE. (AC = 1, T = 1, candidate RS ID)

[0372] --- In an embodiment, the candidate RS ID can be the index of the entry in the list of candidate RSs corresponding to the SSB / CSI RS of the TRP with SS-RSRP / CSI-RSRP above a threshold. If the list is common to all TRPs, the TRP can be identified implicitly. If the list of candidate beam RSs is different for different TRPs, the entries in the multiple lists of candidate beam RSs can be indexed sequentially starting from the first list. In an embodiment, in addition to the candidate RS ID, the TRP ID can also be included. It should be noted that in case the TRP ID is not explicitly included in the beam failure detection and recovery configuration, a set ID or pool ID or list ID corresponding to the different sets of BFD RSs and candidate beam RSs is included. Set 0 / pool 0 / list 0 of BFD RSs corresponds to set 0 / pool 0 / list 0 of candidate beam RSs, set 1 / pool 1 / list 1 of BFD RSs corresponds to set 1 / pool 1 / list 1 of candidate beam RSs.

[0373] In an alternative embodiment, the BFR MAC CE includes:

[0374] - bitmap, where each bit corresponds to a serving cell, the bit corresponding to the SpCell where beam failure was detected is set to 1.

[0375] If there is at least one RS (SSB / CSI RS) with RSRP above the threshold among the candidate beam RSs of the TRP of the SpCell where beam failure was detected and recovery was initiated, then AC = 1, candidate RS ID, TRP ID, zero or more R bits.

[0376] - If there is no RS (SSB / CSI RS) with RSRP above the threshold among the candidate beam RSs of the TRP of the SpCell where beam failure was detected and recovery was initiated, then AC = 0, TRP ID and zero or more R bits.

[0377] - include in the MAC subheader of the BFR MAC CE a reserved LCID, where the reserved LCID is for the BFR MAC CE of the BFR of the TRP of the serving cell. This LCID is different from the LCID included in the MAC subheader of the BFR MAC CE of the BFR of the serving cell.

[0378] - In some embodiments, otherwise, if beam failure of all TRPs of the SpCell is detected, as explained previously, the UE initiates beam failure recovery of the SpCell:

[0379] - trigger random access on the SpCell.

[0380] - perform CFRA if there is at least one RS (SSB / CSI RS) with RSRP above the threshold among the RSs in the list of candidate beam RSs of the SpCell.

[0381] - Otherwise, the UE:

[0382] - performs CBRA.

[0383] - generates a BFR MAC CE.

[0384] - the BFR MAC CE includes a bitmap, where each bit corresponds to a serving cell. The bit corresponding to the SpCell is set to 1.

[0385] - In embodiments, the beam failure recovery information of the SpCell is not included.

[0386] - In alternative embodiments, the beam failure recovery information of the failed TRP can be included. For example, the Figure 6 and Figure 7The format of the illustrated BFR MAC CE 600, 700 is used to indicate beam failure recovery information. The BFR MAC CE can be generated and transmitted in MsgA or Msg3 to include the BFR information for another TRP or two TRPs in a similar way as in the case of the other formats as explained in Embodiment 1 of the beam failure recovery procedure for SCell. Figure 6 and Figure 7 The individual fields are set in a similar way as in the case of SCell BFR and other formats as explained in Embodiment 1 of the beam failure recovery procedure for SCell supporting multiple TRPs.

[0387] It is noted that in an embodiment, the BFR MAC CE can be generated and transmitted in MsgA or Msg3 to include the BFR information for another TRP or two TRPs even in the case of CFRA.

[0388] In an embodiment, for BFR of a set / pool of BFD RSs or TRP of SpCell, if a PDCCH addressed to C-RNTI indicating an uplink grant for new transmission is received for the HARQ process of the transmission of the BFR MAC CE or truncated BFR MAC CE for beam failure recovery information for the set / pool of BFD RSs or TRP containing this serving cell, the UE sets the BFI counter corresponding to the set / pool of BFD RSs or TRP to zero and cancels all triggered BFR for the set / pool of BFD RSs or TRP of this serving cell and considers the BFR for the set / pool of BFD RSs or TRP of SpCell successfully completed.

[0389] In an embodiment, when a MAC PDU is transmitted and this PDU includes a BFR MAC CE or truncated BFR MAC CE containing beam failure information for the set / pool of BFD RSs or TRP of SPCell, all BFRs triggered for the set / pool of BFD RSs or TRP of SPCell can be cancelled.

[0390] In an embodiment, for each pending SR that is not triggered according to the BSR procedure of a serving cell, the MAC entity can:

[0391] If this SR is triggered by beam failure recovery of a set / pool of BFD SRs or TRP of a serving cell (or SCell) and a MAC PDU is transmitted and this PDU includes a BFR MAC CE or truncated BFR MAC CE containing beam failure information for the set / pool of BFD RSs or TRP of the serving cell (or SCell);

[0392] It is noted that the beam failure recovery of a set / pool of BFD RSs or TRP of a serving cell can also be referred to as M-TRP BFR of a serving cell or partial BFR of a serving cell or enhanced BFR of a serving cell.

[0393] Embodiment 2A:

[0394] - In some embodiments, if beam failure of a set / pool of BFD RSs of the SpCell is detected, as explained previously, the UE:

[0395] -- triggers BFR for the set / pool of BFD RSs of the SpCell.

[0396] SR is triggered if UL grant is not available to transmit the BFR MAC CE or the truncated BFR MAC CE, or if UL grant is available but cannot accommodate the BFR MAC CE and its header or the truncated BFR MAC CE and its subheader. The (truncated) BFR MAC CE and its header can be accommodated.

[0397] -- The BFR MAC CE is transmitted in the UL grant if the UL grant is available and can accommodate the (truncated) BFR MAC CE and its header. The enhanced format of the BFR MAC CE 1200, 1300 is illustrated in Figure 12 and Figure 13 The BFR MAC CE is generated as follows:

[0398] --- indicates the set / pool of BFD RSs among multiple sets / pools of BFD RSs that detected beam failure (T = 1 is set).

[0399] --- indicates the set / pool of BFD RSs that detected beam failure and initiated beam failure recovery in the BFR MAC CE if there is no RS (SSB / CSI RS) with RSRP above a threshold among the candidate RSs corresponding to the set / pool that detected beam failure and initiated recovery. (AC = 0, T = 1, set ID, R bit).

[0400] --- Otherwise, the BFR MAC CE includes the RS ID of the candidate RS from the candidate beam RSs of the set / pool that detected beam failure. (AC = 1, T = 1, candidate RS ID)

[0401] - The candidate RS ID is the index of the entry in the candidate RS list. In an embodiment, the candidate RS ID can be the index of the entry in the candidate RS list corresponding to the SSB / CSI RS of the TRP whose SS-RSRP / CSI-RSRP is above the threshold. If the list is common to all TRPs, the TRP can be identified implicitly. If the candidate beam RS list is different for different TRPs, the entries in the multiple candidate beam RS lists can be indexed in order starting from the first list. In an embodiment, in addition to the candidate RS ID, a TRP ID can also be included. It should be noted that in case the TRP ID is not explicitly included in the beam failure detection and recovery configuration, a set ID or pool ID or list ID corresponding to the different sets of BFD RS and candidate beam RS is included. Set 0 / pool 0 / list 0 of BFD RS corresponds to set 0 / pool 0 / list 0 of candidate beam RS, set 1 / pool 1 / list 1 of BFD RS corresponds to set 1 / pool 1 / list 1 of candidate beam RS.

[0402] In an alternative embodiment, the BFR MAC CE includes:

[0403] - A bitmap, where each bit corresponds to a serving cell, the bit corresponding to the SpCell where the beam failure is detected is set to 1.

[0404] If there is at least one RS (SSB / CSI RS) with RSRP above the threshold among the candidate beam RS of the set or pool of the SpCell where the beam failure is detected and recovery is initiated, it is AC = 1, candidate RS ID, TRP ID, zero or more R bits.

[0405] - If there is no RS (SSB / CSI RS) with RSRP above the threshold among the candidate beam RS of the set or pool of the SpCell where the beam failure is detected and recovery is initiated, it is AC = 0, TRP ID and zero or more R bits.

[0406] - A reserved LCID is included in the MAC subheader of the BFR MAC CE, where the reserved LCID is the BFR MAC CE for BFR of the TRP of the serving cell. This LCID is different from the LCID included in the MAC subheader of the BFR MAC CE for BFR of the serving cell.

[0407] - Otherwise, if the beam failure of all sets / pools of BFD RS of the SpCell is detected, as explained previously, the UE initiates the beam failure recovery of the SpCell:

[0408] - Trigger random access on the SpCell.

[0409] --- If there is at least one RS (SSB / CSI RS) with RSRP above the threshold among the RSs in the candidate beam RS list of the SpCell, CFRA is performed.

[0410] -- Otherwise, the UE can:

[0411] --- CBRA is performed.

[0412] --- The BFR MAC CE is generated.

[0413] The BFR MAC CE includes a bitmap, where each bit corresponds to a serving cell. The bit corresponding to the SpCell is set to 1.

[0414] In an embodiment, the beam failure recovery information for the SpCell is not included.

[0415] In an alternative embodiment, the beam failure recovery information for the failed TRP (i.e. the set / pool / list of BFD RSs where the beam failure is detected) can be included. For example, the beam failure recovery information can be indicated using the format of the BFR MAC CE 1200, 1300 shown in Figure 12 and Figure 13 The respective fields can be set in a similar way as for the case of SCell BFR. Figure 12 and Figure 13

[0416] It is noted that in an embodiment, even in the case of CFRA, the BFR MAC CE can be generated and transmitted in MsgA or Msg3 to include the BFR information for another set / pool or both sets / pools.

[0417] In an embodiment, for the BFR of the set / pool of BFD RSs or TRP of the SpCell, if a PDCCH addressed to the C-RNTI indicating the uplink grant for the new transmission is received for the HARQ process of the transmission of the BFR MAC CE or the truncated BFR MAC CE for the beam failure recovery information for the set / pool of BFD RSs or TRP containing this serving cell, the UE sets the BFI counter corresponding to the set / pool of BFD RSs or TRP to zero and cancels all triggered BFR for the set / pool of BFD RSs or TRP of this serving cell and considers the BFR for the set / pool of BFD RSs or TRP of the SpCell successfully completed.

[0418] ​In an embodiment, when a MAC PDU is transmitted and this PDU includes a BFR MAC CE or truncated BFR MAC CE containing beam failure information of the set / pool of BFD RSs or TRP of the SpCell, all BFR triggered for the set / pool of BFD RSs or TRP of the SpCell can be cancelled.

[0419] In an embodiment, for each pending SR not triggered according to the BSR procedure of the serving cell, the MAC entity can:

[0420] If this SR is triggered by the beam failure recovery of the set / pool of BFD RSs or TRP of the serving cell (or SCell), and a MAC PDU is transmitted and this PDU includes a BFR MAC CE or truncated BFR MAC CE containing beam failure information of the set / pool of BFD RSs or TRP of the serving cell (or SCell);

[0421] It should be noted that the beam failure recovery of the set / pool of BFD RSs or TRP of the serving cell can also be referred to as M-TRP BFR of the serving cell or partial BFR of the serving cell or enhanced BFR of the serving cell.

[0422] It should be noted that the beam failure recovery of the set / pool of BFD RSs or TRP of the serving cell can also be referred to as M-TRP BFR of the serving cell or partial BFR of the serving cell or enhanced BFR of the serving cell.

[0423] Embodiment 3:

[0424] - In some embodiments, if the beam failure detection indication of the TRP of the SpCell is received for a configurable number of times within the timer interval, or if the beam failure of the TRP of the SpCell is detected, as previously explained, the UE:

[0425] - Trigger BFR for the TRP of the SCell

[0426] - Trigger SR if UL grant is not available to transmit the BFR MAC CE or truncated BFR MAC CE, or if UL grant is available but cannot accommodate the BFR MAC CE and its header or truncated BFR MAC CE and its subheader; (truncated) BFR MAC CE and its header can be accommodated.

[0427] - Transmit the BFR MAC CE in the UL grant if the UL grant is available and can accommodate (truncated) BFR MAC CE and its header.

[0428] In an embodiment, the SR triggering and the generation and transmission of the BFR MAC CE as explained above are only performed if there is at least one serving cell for which the BFR is triggered and not cancelled and the evaluation of the candidate beams in the candidate beam list of the TRP for which the beam failure is detected is completed.

[0429] The enhanced format of the BFR MAC CE 600, 700 is illustrated in Figure 6 and Figure 7 The BFR MAC CE is generated as follows:

[0430] - If there is no RS (SSB / CSI RS) with RSRP above a threshold among the RSs of the TRP of the SpCell that initiated the beam failure recovery, indicate which TRP failed in the BFR MAC CE. (AC=0, E=0, TRP ID, R bit).

[0431] - Else: Include the RS IDs of the TRP of the SpCell in the BFR MAC CE. (AC=1, E=0, Candidate RS IDs).

[0432] - The candidate RS IDs are the indices of the entries in the candidate RS list.

[0433] In an embodiment, the candidate RS IDs can be the indices of the entries in the candidate RS list corresponding to the SSB / CSI RSs of the TRP with SS-RSRP / CSI-RSRP above a threshold. If the list is common to all TRPs, the TRP can be identified implicitly. If the candidate beam RS list is different for different TRPs, the entries in the multiple candidate beam RS lists can be indexed sequentially starting from the first list. In an embodiment, in addition to the candidate RS IDs, the TRP ID can also be included. It should be noted that in case the TRP ID is not explicitly included in the beam failure detection and recovery configuration, a set ID or pool ID or list ID corresponding to the different sets of BFD RSs and candidate beam RSs is included. Set 0 / pool 0 / list 0 of BFD RSs corresponds to set 0 / pool 0 / list 0 of candidate beam RSs, set 1 / pool 1 / list 1 of BFD RSs corresponds to set 1 / pool 1 / list 1 of candidate beam RSs.

[0434] - Else, if the beam failure detection indication of the SpCell is received for a configurable number of times within the timer interval, or if the beam failure of all TRPs of the SpCell is detected, as explained previously, the UE initiates the beam failure recovery of the SpCell:

[0435] - Trigger random access on the SpCell.

[0436] --- If there is at least one RS (SSB / CSI RS) with RSRP above the threshold among the RSs in the candidate beam RS list of the SpCell, perform CFRA.

[0437] -- Otherwise, the UE can:

[0438] --- Perform CBRA.

[0439] --- Generate the BFR MAC CE. Transmit the BFR MAC CE in MsgA or Msg3. The enhanced format of the BFR MAC CE 600, 700 is illustrated in Figure 6 and Figure 7 . The BFR MAC CE is generated as follows:

[0440] --- The BFR MAC CE includes a bitmap, where each bit corresponds to a serving cell. Set the bit corresponding to the SpCell to 1.

[0441] --- Add the beam failure recovery information for each failed TRP (i.e., one AC octet per failed TRP).

[0442] --- For the beam failure recovery information for a TRP.

[0443] --- Set E to 1 or 0 to indicate whether the following is the beam failure recovery information for another TRP of the same serving cell or not, respectively.

[0444] --- If there is no RS (SSB / CSI RS) with RSRP above the threshold among the candidate RSs of this TRP of the serving cell where the beam failure recovery is initiated:

[0445] --- Set AC = 0; include the TRP ID, R bits.

[0446] --- Otherwise:

[0447] --- Set AC = 1; include the candidate RS ID, i.e., the ID of the SSB / CSI RS of the TRP with SS-RSRP / CSI-RSRP above the threshold.

[0448] --- In an embodiment, the candidate RS ID is the index of the entry in the candidate RS list corresponding to the SSB / CSI RS of the TRP with SS-RSRP / CSI-RSRP above the threshold. The TRP can be identified implicitly since the list is common to all TRPs. In an embodiment, the TRP ID is also included.

[0449] It should be noted that in embodiments, BFR MAC CE can be generated and transmitted in MsgA or Msg3 to include BFR information of another TRP or two TRPs even in CFRA case.

[0450] In embodiments, for BFR of a TRP or a set / pool of BFD RSs of a SpCell, if a PDCCH addressed to C-RNTI indicating a new transmission of uplink grant is received for the HARQ process of the transmission of BFR MAC CE or truncated BFR MAC CE for beam failure recovery information of a set / pool of BFD RSs or a TRP containing this serving cell, the UE sets the BFI counter corresponding to the set / pool of BFD RSs or the TRP to zero and cancels all triggered BFRs of the set / pool of BFD RSs or the TRP of this serving cell and considers the BFR of the TRP or the set / pool of BFD RSs of the SpCell successfully completed.

[0451] In embodiments, when a MAC PDU is transmitted and this PDU includes BFR MAC CE or truncated BFR MAC CE containing beam failure information of a set / pool of BFD RSs or a TRP of SPCell, all BFRs triggered for the set / pool of BFD RSs or the TRP of SPCell can be cancelled.

[0452] In embodiments, for each pending SR that is not triggered according to a BSR procedure of a serving cell, the MAC entity can:

[0453] If this SR is triggered by a beam failure recovery of a set / pool of BFD RSs or a TRP of a serving cell (or SCell) and a MAC PDU is transmitted and this PDU includes BFR MAC CE or truncated BFR MAC CE containing beam failure information of a set / pool of BFD RSs or a TRP of the serving cell (or SCell);

[0454] It should be noted that the beam failure recovery of a set / pool of BFD RSs or a TRP of a serving cell can also be referred to as M-TRP BFR of a serving cell or partial BFR of a serving cell or enhanced BFR of a serving cell.

[0455] Embodiment 3A:

[0456] In some embodiments, if beam failure detection indications of a set / pool of BFD RSs of a SpCell are received for a configurable number of times within a timer interval, or if a beam failure of a set / pool of BFD RSs of a SpCell is detected, as previously explained, the UE:

[0457] -- Set / pool of BFD RSs targeting SpCell, triggering BFR

[0458] If UL grant is not available to transmit BFR MAC CE or truncated BFR MAC CE, SR is triggered, or if UL grant is available but cannot accommodate BFR MAC CE and its header or truncated BFR MAC CE and its subheader, SR is triggered. (Truncated) BFR MAC CE and its header can be accommodated

[0459] -- If UL grant is available and can accommodate (truncated) BFR MAC CE and its header, BFR MAC CE is transmitted in the UL grant.

[0460] In embodiments, the SR triggering and the generation and transmission of the BFR MAC CE as explained above are only performed if there is at least one serving cell for which BFR is triggered and not cancelled and the evaluation of the candidate beams in the candidate beam list corresponding to the set / pool of BFD RSs for which beam failure is detected is completed.

[0461] The enhanced format of the BFR MAC CE 800, 900 is illustrated in Figure 8 and Figure 9 The BFR MAC CE is generated as follows:

[0462] --- If there is no RS (SSB / CSI RS) with RSRP above the threshold among the candidate beam RSs of the set / pool of SCells for which beam failure is detected and recovery is initiated, indicate which set / pool has failed in the BFR MAC CE. (AC=0, E=0, Set ID / pool ID, R bit).

[0463] --- Else: include the RS ID, i.e., the ID of the SSB / CSI RS with SS-RSRP / CSI-RSRP above the threshold among the candidate RSs of the set / pool of candidate RSs corresponding to the set / pool of BFD RSs of the serving cell for which beam failure is detected: set AC=1, E=0, candidate RS ID. The candidate RS ID is the index of the entry in the list of candidate RSs. If the list of candidate beam RSs is different for different sets / pools, the entries in the multiple lists of candidate beam RSs can be indexed in order starting from the first list. In embodiments, the set I / pool ID can also be included.

[0464] - Else, if beam failure detection indication of the SpCell is received for a configurable number of times within the timer interval, or if beam failure of all sets / pools of BFD RSs of the SpCell is detected, as previously explained, the UE initiates beam failure recovery of the SpCell:

[0465] -- trigger random access on SpCell.

[0466] --- if there is at least one RS (SSB / CSI RS) with RSRP above a threshold among the RSs in the candidate beam RS list of SpCell, perform CFRA.

[0467] -- Otherwise, the UE:

[0468] --- perform CBRA.

[0469] --- generate BFR MAC CE. Transmit the BFR MAC CE in MsgA or Msg3. The enhanced format of BFR MAC CE is shown in Figure 8 and Figure 9 . Generate BFR MAC CE as follows:

[0470] --- BFR MAC CE includes a bitmap, where each bit corresponds to a serving cell. Set the bit corresponding to SpCell to 1.

[0471] --- add beam failure recovery information for each set / pool of SCells for which beam failure is detected (i.e., one AC octet for each set / pool of SCells for which beam failure is detected).

[0472] --- for beam failure recovery information for a set / pool of SCells for which beam failure is detected.

[0473] --- set E to 1 or 0 to indicate whether the beam failure recovery information for another set / pool of SCells for which beam failure is detected of the same serving cell is

[0474] --- if there is no RS (SSB / CSI RS) with RSRP above a threshold among the candidate beam RSs of the set / pool of SCells for which beam failure is detected and recovery is initiated:

[0475] --- set AC = 0; include set ID / pool ID, R bits.

[0476] --- Otherwise:

[0477] - Set AC = 1; include candidate RS ID, i.e., ID of SSB / CSI RS whose SS-RSRP / CSI-RSRP is above the threshold among the candidate RSs in the set / pool of candidate RSs corresponding to the set / pool of BFD RSs of the serving cell where beam failure is detected. Set AC = 1, E = 0, candidate RS ID. The candidate RS ID is the index of the entry in the candidate RS list. If the candidate beam RS list is different for different set / pool, the entries in the multiple candidate beam RS lists can be indexed in order starting from the first list. In an embodiment, the set I / pool ID can also be included.

[0478] It should be noted that in an embodiment, the BFR MAC CE can also be generated and transmitted in MsgA or Msg3 to include the BFR information of the set / pool of BFD RSs of the serving cell where beam failure is detected even in the CFRA case.

[0479] It should be noted that the beam failure recovery of the set / pool of BFD RSs or TRPs of the serving cell can also be referred to as M-TRP BFR of the serving cell or partial BFR of the serving cell or enhanced BFR of the serving cell.

[0480] In an embodiment, for the BFR of the set / pool of BFD RSs or TRPs of the SpCell, if the PDCCH addressed to C-RNTI indicating the new transmission of the uplink grant is received for the HARQ process of the transmission of the BFR MAC CE or truncated BFR MAC CE containing the beam failure recovery information of the set / pool of BFD RSs or TRPs of this serving cell, the UE sets the BFI counter corresponding to the set / pool of BFD RSs or TRPs to zero and cancels all triggered BFRs of the set / pool of BFD RSs or TRPs of this serving cell and considers the BFR of the set / pool of BFD RSs or TRPs of the SpCell successfully completed.

[0481] In an embodiment, when a MAC PDU is transmitted and this PDU includes the BFR MAC CE or truncated BFR MAC CE containing the beam failure information of the set / pool of BFD RSs or TRPs of the SPCell, all BFRs triggered for the set / pool of BFD RSs or TRPs of the SPCell can be cancelled.

[0482] In an embodiment, for each pending SR that is not triggered according to the BSR procedure of the serving cell, the MAC entity can:

[0483] If this SR is triggered by the set / pool of BFD RSs of the serving cell (or SCell) or beam failure recovery of the TRP and a MAC PDU is transmitted and this PDU includes a BFR MAC CE or truncated BFR MAC CE containing beam failure information of the set / pool of BFD RSs of the serving cell (or SCell) or TRP.

[0484] It should be noted that the beam failure recovery of the set / pool of BFD RSs of the serving cell or TRP can also be referred to as M-TRP BFR of the serving cell or partial BFR of the serving cell or enhanced BFR of the serving cell.

[0485] Embodiment 4:

[0486] - If one or more TRPs of the SCell meet the BFD criteria (i.e., BFD of one or more TRPs of the SpCell is detected, as previously explained), the UE initiates beam failure recovery of the TRP of the SpCell:

[0487] - Trigger random access on the SpCell.

[0488] - Transmit a BFR MAC CE in Msg3 or MsgA. The enhanced format of the BFR MAC CE 600, 700 is shown in Figure 6 and Figure 7 The BFR MAC CE is generated as follows:

[0489] - The BFR MAC CE includes a bitmap, where each bit corresponds to a serving cell. The bit corresponding to the SpCell for which the beam failure is detected is set to 1.

[0490] - Beam failure recovery information of each failed TRP of the SpCell is added (i.e., one AC octet per failed TRP).

[0491] - For the beam failure recovery information of the TRP of the SpCell:

[0492] - E is set to 1 or 0 to indicate whether the following is the beam failure recovery information of another TRP of the same serving cell or not, respectively. It should be noted that if only the beam failure recovery information of one TRP is included in the BFR MAC CE, the E field can not be needed / included in the BFR MAC CE.

[0493] - If there is no RS (SSB / CSI RS) with RSRP above the threshold among the candidate RSs of this TRP of the serving cell for which the beam failure is detected (and recovery is initiated):

[0494] - Set AC = 0; include TRP ID, R-bit. Note that in case TRP ID is not explicitly included in the beam failure detection and recovery configuration, include set ID or pool ID or list ID corresponding to different sets of BFD RS and candidate beam RS. Set 0 / pool 0 / list 0 of BFD RS corresponds to set 0 / pool 0 / list 0 of candidate beam RS, set 1 / pool 1 / list 1 of BFD RS corresponds to set 1 / pool 1 / list 1 of candidate beam RS. Set n / pool n / list n of BFD RS corresponds to set n / pool n / list n of candidate beam RS

[0495] - Else:

[0496] - Set AC = 1; include candidate RS ID, i.e., ID of SSB / CSI RS of TRP with SS-RSRP / CSI-RSRP above threshold.

[0497] - In an embodiment, candidate RS ID can be an index of an entry in a candidate RS list corresponding to SSB / CSI RS of TRP with SS-RSRP / CSI-RSRP above threshold. If the list is common to all TRPs, TRP can be identified implicitly. If candidate beam RS list is different for different TRPs, entries in multiple candidate beam RS lists can be indexed in order starting from the first entry in the first list. In an embodiment, TRP ID can also be included. Note that in case TRP ID is not explicitly included in the beam failure detection and recovery configuration, include set ID or pool ID or list ID corresponding to different sets of BFD RS and candidate beam RS. Set 0 / pool 0 / list 0 of BFD RS corresponds to set 0 / pool 0 / list 0 of candidate beam RS, set 1 / pool 1 / list 1 of BFD RS corresponds to set 1 / pool 1 / list 1 of candidate beam RS.

[0498] Embodiment 4A:

[0499] - In some embodiments, if one or more sets / pools of BFD RS of SpCell satisfy BFD criterion (i.e., beam failure of one or more sets / pools of BFD RS of SpCell is detected, as explained earlier), the UE initiates beam failure recovery of one or more sets / pools of BFD RS of SpCell:

[0500] - Trigger random access on SpCell.

[0501] - Transmit BFR MAC CE in Msg3 or MsgA. For example, enhanced format of BFR MAC CE 800, 900 is in Figure 8 and Figure 9BFR MAC CE can be generated by the UE as follows:

[0502] -- The BFR MAC CE can include a bitmap, where each bit corresponds to a serving cell. The bit corresponding to the SpCell where beam failure is detected is set to 1.

[0503] -- Add beam failure recovery information for each set / pool of BFD RSs where beam failure is detected (i.e., one AC octet for each set / pool of BFD RSs).

[0504] -- For the beam failure recovery information for a set / pool of BFD RSs:

[0505] --- Set E to 1 or 0 to indicate whether the following is the beam failure recovery information for another set / pool of BFD RSs of the same serving cell or not. It should be noted that if only the beam failure recovery information for one TRP or one set / pool of BFD RSs is included in the BFR MAC CE, the E field can not be needed / included in the BFR MAC CE.

[0506] --- If there is no RS (SSB / CSI RS) with RSRP above the threshold among the candidate RSs in the set / pool of candidate RSs corresponding to the set / pool of BFD RSs of the serving cell where beam failure is detected:

[0507] ---- Set AC = 0; include set / pool ID, R bits.

[0508] --- Else:

[0509] ---- Set AC = 1; include candidate RS ID, i.e., the ID of the SSB / CSI RS with SS-RSRP / CSI-RSRP above the threshold among the candidate RSs in the set / pool of candidate RSs corresponding to the set / pool of BFD RSs of the serving cell where beam failure is detected

[0510] ---- In an embodiment, the candidate RS ID can be the index of the entry in the list of candidate RSs corresponding to the SSB / CSI RS. If there are multiple lists of candidate beam RSs, the entries in the multiple lists of candidate beam RSs can be indexed in order starting from the first entry in the first list. In an embodiment, the set / pool ID can also be included.

[0511] Method 2:

[0512] Beam failure detection and beam failure recovery triggering for a serving cell:

[0513] For beam failure detection in a serving cell, the UE can receive from the gNB a beam failure detection configuration for that serving cell, as explained previously. The UE can determine whether the received beam failure detection configuration includes beam failure detection RSs for multiple TRPs.

[0514] If the beam failure detection configuration includes beam failure detection RSs for multiple TRPs (or in other words, multiple sets / pools / groups of beam failure detection RSs are received), the UE detects a beam failure and triggers beam failure recovery for the serving cell, as follows:

[0515] 1. The UE (PHY) periodically measures the beam failure detection RSs of the TRPs of the serving cell in the beam failure detection configuration (or measures the beam failure detection RSs of all sets / pools / groups of beam failure detection RSs).

[0516] 2. If all BFD RSs of any TRP of the serving cell are below a threshold, or the hypothetical PDCCH BLER determined based on the measurements of the beam failure detection RSs is above the threshold for all beam failure detection RSs of any TRP:

[0517] - considers that a beam failure instance has occurred, i.e., the PHY layer transmits a beam failure instance indication to the MAC layer.

[0518] In other words, if all BFD RSs in any set / pool / group of BFD RSs of the serving cell are below a threshold, or the hypothetical PDCCH BLER determined based on the measurements of the beam failure detection RSs is above the threshold for all beam failure detection RSs in any set / pool / group of BFD RSs of the serving cell:

[0519] - considers that a beam failure instance has occurred, i.e., the PHY layer transmits a beam failure instance indication to the MAC layer.

[0520] 3. Upon reception of a beam failure instance indication for the serving cell from the PHY layer,

[0521] - starts or restarts the beamFailureDetectionTimer for the serving cell.

[0522] - updates the BFI counter for the serving cell.

[0523] It should be noted that only one timer and counter are maintained per serving cell, regardless of the number of TRPs in the serving cell.

[0524] 4. If the BFI counter >= beamFailureInstanceMaxCount for the serving cell: considers that a beam failure is detected for the serving cell and initiates beam failure recovery for the serving cell

[0525] If the beam failure detection configuration does not include beam failure detection RSs of multiple TRPs, the UE detects a beam failure and triggers beam failure recovery as follows:

[0526] 1. The UE (PHY) periodically measures the beam failure detection RSs of the serving cell in the beam failure detection configuration.

[0527] 2. If all BFD RSs of the serving cell are below a threshold, or the hypothetical PDCCH BLER determined based on the measurements of the beam failure detection RSs is higher than the threshold for all beam failure detection RSs of the serving cell:

[0528] - considers a beam failure instance occurred, i.e. the PHY layer transmits a beam failure instance indication to the MAC layer.

[0529] 3. Upon reception of a beam failure instance indication of the serving cell from the PHY layer,

[0530] - starts or restarts the beamFailureDetectionTimer for the serving cell from which the beam failure instance indication was received from the PHY layer. One beamFailureDetectionTimer is maintained for the serving cell.

[0531] - updates the BFI counter for the serving cell from which the beam failure instance indication was received from the PHY. One BFI counter is maintained for the serving cell.

[0532] 4. If the BFI counter >= beamFailureInstanceMaxCount for the serving cell: the beam failure of the serving cell can be considered detected and the beam failure recovery for the serving cell can be initiated.

[0533] Beam failure recovery procedure for a serving cell supporting multiple TRPs:

[0534] - If the serving cell meets the BFD criteria (as explained above),

[0535] -- If the serving cell is an SCell, the UE:

[0536] --- triggers SCell BFR.

[0537] --- If UL-SCH resources are available for a new transmission and if, as a result of LCP, the UL-SCH resources can accommodate the BFR MAC CE and its subheaders: the UE generates the BFR MAC CE and transmits a MAC PDU including the BFR MAC CE to the gNB.

[0538] --- Else if UL-SCH resources are available for a new transmission and if, as a result of LCP, the UL-SCH resources can accommodate the truncated BFR MAC CE and its sub-headers: the UE generates the truncated BFR MAC CE and the UE transmits a MAC PDU including the truncated BFR MAC CE to the gNB.

[0539] --- Else: the UE triggers an SR for SCell beam failure recovery of the SCell.

[0540] -- Else, the UE:

[0541] --- triggers a random access procedure on the SpCell.

[0542] --- generates the (truncated) BFR MAC CE and transmits a MAC PDU including the BFR MAC CE in MsgA or Msg3 during the random access procedure.

[0543] - In an embodiment, the enhanced format of the BFR MAC CE is illustrated in Figure 6 and Figure 7 . The (truncated) BFR MAC CE is generated as follows:

[0544] -- The (truncated) BFR MAC CE can include a bitmap, where each bit corresponds to a serving cell. The bit corresponding to the serving cell where the beam failure is detected is set to 1.

[0545] -- Add beam failure recovery information for each failed TRP of the serving cell (i.e. one AC octet per failed TRP), or add beam failure recovery information per set / pool / list of candidate beam RSs.

[0546] -- For the beam failure recovery information of the set / pool / list of candidate beam RSs or TRP

[0547] --- Set E to 1 or 0 to indicate whether the following is another beam failure recovery information of the same serving cell or not

[0548] --- If there is no RS (SSB / CSI RS) with RSRP above a threshold among the candidate RSs of this TRP of the serving cell where the beam failure is detected (and recovery is initiated):

[0549] - Set AC = 0; include TRP ID, R bit. Note that in case TRP ID is not explicitly included in the beam failure detection and recovery configuration, include set ID or pool ID or list ID corresponding to different sets of BFD RS and candidate beam RS. Set 0 / pool 0 / list 0 of BFD RS corresponds to set 0 / pool 0 / list 0 of candidate beam RS, set 1 / pool 1 / list 1 of BFD RS corresponds to set 1 / pool 1 / list 1 of candidate beam RS.

[0550] - Else:

[0551] - Set AC = 1; include candidate RS ID, i.e., ID of SSB / CSI RS of TRP whose SS-RSRP / CSI-RSRP is higher than threshold.

[0552] - In an embodiment, candidate RS ID can be index of entry in candidate RS list corresponding to SSB / CSI RS of TRP whose SS-RSRP / CSI-RSRP is higher than threshold. If the list is common to all TRPs, TRP can be identified implicitly. If candidate beam RS list is different for different TRPs, entries in multiple candidate beam RS lists can be indexed in order starting from the first list. In an embodiment, TRP ID can also be included. Note that in case TRP ID is not explicitly included in the beam failure detection and recovery configuration, include set ID or pool ID or list ID corresponding to different sets of BFD RS and candidate beam RS. Set 0 / pool 0 / list 0 of BFD RS corresponds to set 0 / pool 0 / list 0 of candidate beam RS, set 1 / pool 1 / list 1 of BFD RS corresponds to set 1 / pool 1 / list 1 of candidate beam RS.

[0553] - In an embodiment, (truncated) BFR MAC CE can be generated as follows:

[0554] - (Truncated) BFR MAC CE includes a bitmap, where each bit corresponds to a serving cell. Set the bit corresponding to the serving cell where beam failure is detected to 1.

[0555] - Add beam failure recovery information for each TRP of the serving cell (i.e., one AC octet per TRP) regardless of whether it is failed or not. Alternatively, add beam failure recovery information per set / pool / list of candidate beam RS. Beam failure recovery information can be added in ascending order of TRP ID / set ID / pool ID / list ID, etc.

[0556] - Beam failure recovery information for set / pool / list of candidate beam RS or TRP

[0557] --- If there is no RS (SSB / CSI RS) with RSRP above threshold among the candidate RSs of this TRP of the serving cell where beam failure is detected (and recovery initiated):

[0558] --- Set AC = 0; include R bit.

[0559] --- (Alternative) Set AC = 0; F = 0 / 1 to indicate whether there is failure; include R bit.

[0560] --- Else:

[0561] --- Set AC = 1; include candidate RS ID, i.e., ID of SSB / CSI RS of the TRP with SS-RSRP / CSI-RSRP above threshold or ID of SSB / CSI RS in the set / pool / list of candidate beam RSs.

[0562] --- In an embodiment, the candidate RS ID can be an index of an entry in the list of candidate RSs corresponding to the SSB / CSI RS with SS-RSRP / CSI-RSRP above threshold.

[0563] The bitmap field in (truncated) BFR MAC CE is defined as follows:

[0564] - SP: This field indicates beam failure detection of SpCell of this MAC entity. SP field is set to 1 to indicate beam failure is detected for SpCell. Otherwise, set to 0;

[0565] - C i (BFR MAC CE): This field indicates beam failure detection and presence of octet containing AC field for SCell with ServCellIndex i. C i field set to 1 indicates beam failure is detected and SCell with ServCellIndex i exists octet containing AC field. C i field set to 0 indicates beam failure is not detected and SCell with ServCellIndex i does not exist octet containing AC field. Octets containing AC field are present in ascending order of ServCellIndex;

[0566] - C i (truncated BFR MAC CE): This field indicates beam failure detection for SCell with ServCellIndex i. C iThe field indicates that beam failure is detected and there can be octets containing AC field for SCell with ServCellIndex i. C i The field indicates that beam failure is not detected and there is no octet containing AC field for SCell with ServCellIndex i. Include octets containing AC field (if exists) in ascending order based on ServCellIndex. The number of included octets containing AC field is maximized without exceeding the available grant size;

[0567] - In an embodiment, the (truncated) BFR MAC CE can be generated as explained in Method 1.

[0568] Method

[0569] In an example embodiment (Option 1), for beam failure detection configuration:

[0570] - The list of BFD RS per BWP can be signaled. In case of multiple TRPs, a one-bit TRP indicator can be included to indicate whether the RS is for TRP 0 or TRP 1.

[0571] In an example embodiment, for beam failure detection triggering of a serving cell:

[0572] - If multiple TRPs are configured in the serving cell, beam failure is considered to be detected when all RS of the TRP in the list of BFD RS of the serving cell are below the threshold.

[0573] - Otherwise, beam failure is considered to be detected when all RS in the list of BFD RS of the serving cell are below the threshold.

[0574] In an example embodiment, for beam failure recovery of SpCell:

[0575] - The list of candidate beam RS per BWP is signaled. In case of multiple TRPs, a one-bit TRP indicator can be included to indicate whether the RS is for TRP 0 or TRP 1.

[0576] - If multiple TRPs are configured:

[0577] - If beam failure detection indication of the TRP of SpCell is received for a configurable number of times within the timer interval: RA is triggered.

[0578] - If there is at least one RS (SSB / CSI RS) with RSRP above the threshold among the RS in the list of candidate beam RS of SpCell associated with the TRP that initiated the beam failure recovery, CFRA is performed.

[0579] -- Otherwise, the UE:

[0580] --- performs CBRA;

[0581] --- generates the BFR MAC CE; and

[0582] --- indicates in the BFR MAC CE which TRP of the SpCell failed

[0583] - Otherwise, the UE:

[0584] -- if beam failure detection indications for the SpCell are received for a configurable number of times within the timer interval: triggers RA.

[0585] --- performs CFRA if there is at least one RS (SSB / CSI RS) with RSRP above a threshold among the RSs in the candidate beam RS list of the SpCell.

[0586] -- Otherwise, the UE:

[0587] --- performs CBRA; and

[0588] --- generates the BFR MAC CE.

[0589] In example embodiments, for beam failure recovery of SCells:

[0590] - the candidate beam RS list per BWP is signaled. In case of multiple TRPs, a one-bit TRP indicator can be included to indicate whether the RS is for TRP0 or TRP 1.

[0591] - if multiple TRPs are configured:

[0592] -- if beam failure detection indications for a TRP of the SCell are received for a configurable number of times within the timer interval, the SCell BFR is triggered.

[0593] -- if UL grant is not available, the UE can trigger SR.

[0594] -- the UE can transmit the BFR MAC CE in the UL grant.

[0595] --- In example embodiments, a single AC octet per SCell can be used.

[0596] - If there is no RS (SSB / CSI RS) with RSRP above a threshold among the RSs of the TRP of the SCell where the beam failure recovery is initiated, indicate which TRP failed in the BFR MAC CE. If there is at least one RS (SSB / CSI RS) with RSRP above a threshold among the RSs of the TRP of the SCell where the beam failure recovery is initiated, include the RS ID in the BFR MAC CE.

[0597] - In another example embodiment, an AC octet per TRP per SCell can be used. For example, the 1st octet can be used for TRP 0 and the 2nd octet can be used for TRP 1.

[0598] - If no TRP failed: AC = 0, F = 0, 6 R bits

[0599] - If a TRP failed and no candidate beams are available: AC = 0, F = 1, 6 R bits.

[0600] - If a TRP failed and candidate beams are available: AC = 1, RS ID.

[0601] - Otherwise, the UE can:

[0602] - If no UL grant is available, trigger an SR; and

[0603] - Transmit the BFR MAC CE in the UL grant.

[0604] - Single AC octet per SCell.

[0605] - If no candidate beams are available: AC = 0, reserved bits.

[0606] - If candidate beams are available, AC = 1, RS ID.

[0607] In an example embodiment (Option 2), for beam failure detection configuration:

[0608] - The BFD RS list can be signaled separately for each TRP per BWP.

[0609] In an embodiment, two lists of groups in the UL BWP configuration can be used instead of a 1-bit indicator (e.g., group 1 can include a list of candidate beam RSs associated with TRP 1 and group 2 can include a list of candidate beam RSs associated with TRP 2). Trigger beam failure detection of the serving cell.

[0610] - If multiple TRPs are configured in the serving cell:

[0611] - A beam failure can be considered detected when all RS in the BFD RS list of the TRP of the serving cell are below the threshold.

[0612] - Else

[0613] - A beam failure can be considered detected when all RS in the BFD RS list of the serving cell are below the threshold.

[0614] In an example embodiment, for beam failure recovery of SpCell:

[0615] - The list of candidate beam RS can be signaled separately for each TRP per BWP.

[0616] - If multiple TRPs are configured:

[0617] - If beam failure detection indications of the TRP of the SpCell are received for a configurable number of times within the timer interval: the UE can trigger RA.

[0618] - If there is at least one RS (SSB / CSI RS) with RSRP above the threshold in the list of candidate beam RS of the TRP of the SpCell where the beam failure recovery is initiated: the UE can perform CFRA.

[0619] - Else, the UE can:

[0620] - Perform CBRA;

[0621] - Generate a BFR MAC CE; and

[0622] - Indicate in the BFR MAC CE which TRP of the SpCell failed

[0623] - Else

[0624] - If beam failure detection indications of the SpCell are received for a configurable number of times within the timer interval: the UE can trigger RA.

[0625] - If there is at least one RS (SSB / CSI RS) with RSRP above the threshold in the list of candidate beam RS of the SpCell: the UE can perform CFRA.

[0626] - Else, the UE can:

[0627] - Perform CBRA; and

[0628] - Generate a BFR MAC CE.

[0629] In an example embodiment, for beam failure recovery of SCell:

[0630] - The list of candidate beam RSs can be signaled individually per TRP per BWP.

[0631] - If multiple TRPs are configured:

[0632] -- If beam failure detection indication is received for a TRP of the SCell for a configurable number of times within the timer interval, SCell BFR is triggered.

[0633] -- If UL grant is not available, SR is triggered; and

[0634] -- BFR MAC CE is transmitted in UL grant.

[0635] --- AC octet per TRP per SCell. For example, 1st octet for TRP 0 and 2nd octet for TRP 1.

[0636] ---- If TRP is not failed: AC = 0, F = 0, 6 R bits.

[0637] ---- If TRP is failed and no candidate beam is available: AC = 0, F = 1, 6 R bits.

[0638] ---- If TRP is failed and candidate beam is available: AC = 1, RS ID.

[0639] - Otherwise, the UE can:

[0640] -- If UL grant is not available, SR is triggered; and

[0641] -- BFR MAC CE is transmitted in UL grant.

[0642] --- Single AC octet per SCell.

[0643] --- If no candidate beam is available: AC = 0, reserved bits.

[0644] --- If candidate beam is available, AC = 1, RS ID.

[0645] Other BFR enhancements.

[0646] Upon detecting beam failure of an SCell, BFR can be triggered. Upon triggering BFR, the UE can transmit the BFR MAC CE in the earliest available UL grant that can accommodate the BFR MAC CE according to LCP. At the time this UL grant is available, the UE can not have measured the candidate beam RSs in the list of candidate beam RSs. Thus, the UE can transmit the BFR MAC CE with AC = 0, and the network can deactivate the SCell based on this. This is not efficient.

[0647] In an example embodiment (Option 1), the MAC entity (i.e., a mac entity included in a UE) can:

[0648] 1> if the beam failure recovery procedure determines that at least one BFR has been triggered and not cancelled; and

[0649] 1> if the UE has measured and evaluated candidate beams in the candidateBeamRSSCellList; (or if the UE has determined the availability of candidate beams in the candidateBeamRSSCellList for beam failure recovery):

[0650] 2> if UL-SCH resources are available for new transmission, and if as a result of LCP, the UL-SCH resources can accommodate the (truncated) BFR MAC CE and its subheader:

[0651] 3> instruct the multiplexing and assembly procedure to generate the BFR MAC CE.

[0652] 2> else if UL-SCH resources are available for new transmission, and if as a result of LCP, the UL-SCH resources can accommodate the truncated BFR MAC CE and its subheader:

[0653] 3> instruct the multiplexing and assembly procedure to generate the truncated BFR MAC CE.

[0654] 2> else:

[0655] 3> for each SCell for which the beam failure recovery procedure determines that at least one BFR has been triggered and not cancelled, trigger an SR for SCell beam failure recovery.

[0656] In an example embodiment (Option 2), the MAC entity can:

[0657] 1> if the beam failure recovery procedure determines that at least one BFR has been triggered and not cancelled; and

[0658] 1> if the UE has measured and evaluated candidate beams in the candidateBeamRSSCellList for at least one SCell for which BFR has been triggered and not cancelled:

[0659] 2> if UL-SCH resources are available for new transmission and if, as a result of LCP, the UL-SCH resources can accommodate the BFR MAC CE and its subheader:

[0660] 3> instruct the multiplexing and assembly procedure to generate the BFR MAC CE.

[0661] 3> in the BFR MAC CE, if beam failure for the SCell with servingCellIndex i is detected, the UE sets the Ci bit to 1 for that SCell; and the UE measured / evaluated candidate beams in the candidateBeamRSSCellList for that SCell (or if the UE has determined the availability of candidate beams in the candidateBeamRSSCellList for beam failure recovery for that SCell):

[0662] 2> else if UL-SCH resources are available for new transmission and if, as a result of LCP, the UL-SCH resources can accommodate the truncated BFR MAC CE and its subheader:

[0663] 3> instruct the multiplexing and assembly procedure to generate the truncated BFR MAC CE.

[0664] 2> else:

[0665] 3> for each SCell for which BFR has been triggered and not cancelled, trigger SR for SCell beam failure recovery.

[0666] According to the above operation, if there are multiple SCells (example SCell1 and SCell 2) for which BFR has been triggered and not cancelled:

[0667] - If the evaluation of candidate beams for SCell 1 is completed but the evaluation of candidate beams for SCell 2 is not completed, the (truncated) BFR MAC CE is generated if the available UL grant can accommodate it with its subheader. In this case, in the MAC CE, the Ci bit corresponding to SCell 2 is set to 0, even if beam failure for SCell 2 is detected; the Ci bit corresponding to SCell 1 is set to 1 because beam failure for SCell 1 is detected and the evaluation of candidate beams is also completed.

[0668] - If the evaluation of candidate beams for SCell 2 is completed but the evaluation of candidate beams for SCell 1 is not completed, the (truncated) BFR MAC CE is generated if the available UL grant can accommodate it with its subheader. In this case, in the MAC CE, the Ci bit corresponding to SCell 1 is set to 0, even if beam failure for SCell 1 is detected; the Ci bit corresponding to SCell 2 is set to 1 because beam failure for SCell 2 is detected and the evaluation of candidate beams is also completed.

[0669] - If the evaluation of candidate beams for SCell 1 is not completed and the evaluation of candidate beams for SCell 2 is not completed, the (truncated) BFR MAC CE is not generated.

[0670] According to the above operation, if there is only one SCell for which BFR has been triggered and has not been cancelled (example SCell 1):

[0671] - If the evaluation of candidate beams for SCell 1 is completed, the BFR MAC CE is generated if the available UL grant can accommodate it with its subheader.

[0672] - If the evaluation of candidate beams for SCell 1 is not completed, the (truncated) BFR MAC CE is not generated.

[0673] In an example embodiment (Option 3), for each serving cell configured for beam failure detection, the MAC entity can:

[0674] 1> if a beam failure instance indication has been received from lower layers:

[0675] 2> start or restart the beamFailureDetectionTimer;

[0676] 2> increment the BFI counter by 1;

[0677] 2> if BFI counter >= beamFailureInstanceMaxCount:

[0678] 3> if the serving cell is an SCell:

[0679] 4> trigger BFR for this serving cell upon determining the availability of a candidate beam in candidateBeamRSSCellList for beam failure recovery;

[0680] 3> else:

[0681] 4> initiate a random access procedure on SpCell upon determining the availability of a candidate beam in candidateBeamRSList for beam failure recovery.

[0682] CG Type 1 configuration and UL TX beam

[0683] Figure 14 A data transmission / reception method between a terminal and a base station for uplink beam transmission according to an embodiment of the disclosure is illustrated.

[0684] For PUSCH transmission, UL TX beam information can be indicated by gNB.

[0685] At step S1410, the UE can transmit SRS using various UL TX beams. SRS resources for transmitting SRS using various UL TX beams can be signaled to the UE by gNB. These resources are identified using SRS resource identifiers (SRIs).

[0686] At step S1415, the gNB can map a CG Type 1 configuration to an UL TX beam. At step S1420, the gNB can indicate the selected UL TX beam using an SRI (e.g., SRI X). For example, the SRI can be indicated in DCI for dynamic grant and CG Type 2. For example, the SRI can be indicated in the configuration of CG Type 1 (refer to Figures 15 to 18 ).

[0687] At step S1425, the UE can transmit an RRC reconfiguration complete message to the gNB using the SRI through the selected UL TX beam.

[0688] At step S1430, the UE can transmit SRS using various UL TX beams. At step S1435, the gNB can update the configuration in case of UL TX beam change. For example, the gNB can map CG Type 1 configuration to the changed UL TX beam. At step S1440, the gNB can use SRI (e.g., SRI Y) to indicate the selected UL TX beam if the UL TX beam changes.

[0689] The problem is that a reconfiguration procedure is needed every time the UL TX beam changes. The next Figure 15 is a diagram for explaining an embodiment of a method of transmitting UL TX beams related to the above problem.

[0690] Method 1:

[0691] Figure 15 A data transmission / reception method between a terminal and a base station for uplink beam transmission according to an embodiment of the disclosure is illustrated.

[0692] In one method of the disclosure (as Figure 16 illustrated), the UE can receive an SRS configuration from the gNB. At step S1510, the UE can transmit SRS using various UL TX beams in the configured SRS resources. At step S1515, the gNB can select an UL TX beam. At step S1520, the gNB can use an SRS resource identifier (SRI) of the SRS resource used by the UE to transmit SRS using the UL TX beam. The gNB can indicate / activate the SRI (e.g., SRI X) to the UE using a MAC CE or DCI. If the SRI is received using the MAC CE, the UE can transmit an acknowledgement MAC CE to the gNB. For a subsequent CG Type 1 grant, the UE can determine the UL TX beam based on this received SRI.

[0693] At step S1525, the gNB can configure the configured grant Type 1 using an RRC reconfiguration message. In addition, at step S1530, the UE can transmit an RRC reconfiguration complete message to the gNB.

[0694] For UL transmission in these configured grants, at step S1535, the UE can use the UL TX beam that the UE has used to transmit in the SRS resource identified by the SRI, which is indicated / activated by the gNB using a MAC CE or DCI.

[0695] At step S1540, the UE can transmit SRS using various UL TX beams. At step S1545, the gNB can identify the UL TX beam if the UL TX beam changes. At step S1550, the gNB can use the UL TX beam to indicate a changed SRI (e.g., SRI Y) of SRS resource used by the UE to transmit SRS. If the SRI changes, at step S1555, the UE can apply the last received SRI in MAC CE or DCI. For CG Type 1 UL transmission, the UE calculates PL based on the SRI indicated by the MAC CE / DCI. It should be noted that for CG Type 2 UL grant and dynamic UL grant, the TCI state or SRI used to determine the UL TX beam and path loss (PL) is indicated in the DCI scheduling those UL grants.

[0696] Figure 16 A data transmission / reception method between a terminal and a base station for uplink beam transmission according to an embodiment of the disclosure is illustrated.

[0697] In an alternative embodiment Figure 16 ), instead of using SRS transmission to determine the UL TX beam, the gNB can indicate (the indication can be in RRC message) the UE to use the activated TCI state to determine the UL TX beam instead of SRI.

[0698] At step S1610, the gNB can transmit an RRC message (e.g., RRC reconfiguration message) including a list of TCI states to the UE. The TCI state can indicate one of SSB / CSIRS. The UE can use the UL TX beam quasi co-located with the RX beam used to receive the SSB / CSIRS of the activated TCI state. For UL transmission, the UE calculates PL based on the activated TCI state.

[0699] At step S1615, the UE can transmit an L1 / L3 measurement report to the gNB. At step S1620, the gNB can transmit a MAC CE or DCI (e.g., TCI state X) including a TCI state based on the received L1 / L3 measurement report.

[0700] At step S1625, the gNB can configure the configured grant Type 1 using RRC reconfiguration message. For UL transmission, the gNB can indicate the UE to use the activated TCI state to determine the UL TX beam. The TCI state can indicate one of SSB / CSI RS. For UL transmission in this configured grant in Type 1, at step S1635, the UE can use the UL TX beam quasi co-located with the RX beam of the SSB / CSI RS used to receive the activated TCI state. For UL transmission in these CG Type grants, the UE can calculate the PL based on the activated TCI state. For example, for CG Type 2 UL grant and dynamic UL grant, the TCI state or SRI used to determine the UL TX beam can be indicated in the DCI scheduling those UL grants.

[0701] For UL transmission, if no indication is received from the gNB to use the activated TCI state to determine the UL TX beam, the UE can use the SRI to determine the UL TX beam and path loss, as explained above.

[0702] At step S1640, the UE can transmit the L1 / L3 measurement report to the gNB. At step S1645, in case of TCI state change, the gNB can transmit a MAC CE or DCI including the TCI state (e.g., TCI state X) based on the received L1 / L3 measurement report (optional step). At step S1650, the UE can transmit in CG Type 1 grant according to the activated TCI state using the UL TX beam. Referring to Figure 17 In case of TCI state change from TCI state X to TCI state Y, the UE can transmit in CG Type 1 grant according to the activated TCI state Y using the UL TX beam.

[0703] Method 2:

[0704] Figure 17 A data transmission / reception method between a terminal and a base station for uplink beam transmission according to an embodiment of the present disclosure is illustrated.

[0705] In another method of the present disclosure (as Figure 18As shown, at step S1705, the UE can receive an SRS configuration from the gNB. At step S1710, the UE can transmit SRS using various UL TX beams in the configured SRS resources. At step S1715, the gNB can select an UL TX beam. At step S1720, the gNB can use the UL TX beam to indicate an SRS resource identifier (SRI) of an SRS resource used by the UE to transmit the SRS. For example, the gNB can use a MAC CE or DCI to indicate / activate the SRI (e.g., SRI X) to the UE. If the SRI is received using the MAC CE, the UE can transmit an acknowledgement MAC CE to the gNB. For a subsequent CG Type 1 grant, the UE can determine the UL TX beam based on this received SRI.

[0706] At step S1725, the gNB can configure the configured grant Type 1 using a RRC reconfiguration message. The gNB can configure one or more CG Type 1 configurations. Each configuration can be mapped to one or more SRIs. The SRIs associated with each CG Type configuration can be signaled by the gNB.

[0707] At step S1730, the UE can transmit a RRC reconfiguration complete message to the gNB.

[0708] At step S1735, the UE can perform UL transmission in the configured CG Type 1 grant associated with the activated SRI (i.e., the SRI received in the MAC CE or DCI activating the SRI) (e.g., SRI X). For the UL transmission in these configured grants, the UE can use the UL TX beam that the UE has used to transmit in the SRS resource identified by the SRI, which is indicated / activated by the gNB using the MAC CE or DCI.

[0709] At step S1740, the UE can transmit SRS using various UL TX beams. At step S1745, if the UL TX beam changes, the gNB can identify the UL TX beam based on the received UL TX beam. At step S1750, the gNB can use the UL TX beam to indicate a changed SRI (e.g., SRI Y) of an SRS resource used by the UE to transmit the SRS. If the SRI changes, at step S1755, the UE can apply the last received SRI in the MAC CE or DCI to determine the CG Type 1 configuration or CG Type 1 grant to use and also determine the PL.

[0710] As another example, for CG Type 2 UL grants and dynamic UL grants, the TCI state or SRI used to determine the UL TX beam and PL can be indicated in the DCI scheduling those UL grants.

[0711] Figure 18 A data transmission / reception method between a terminal and a base station for uplink beam transmission according to an embodiment of the disclosure is shown.

[0712] In an alternative embodiment ( Figure 19 ), instead of using SRS transmission to determine the UL TX beam, the gNB can instruct (e.g., the instruction can be in an RRC message) the UE to use the activated TCI state to determine the UL TX beam instead of SRI. The TCI state can indicate one of SSB / CSI RS. The UE can use the UL TX beam quasi co-located with the RX beam used to receive the SSB / CSI RS of the activated TCI state.

[0713] At step S1810, the gNB can transmit an RRC message (e.g., RRC reconfiguration message) including a list of TCI states to the UE. At step S1815, the UE can transmit an L1 / L3 measurement report to the gNB. At step S1820, the gNB can transmit a MAC CE or DCI including SRI (e.g., SRI X) based on the received L1 / L3 measurement report.

[0714] At step S1825, the gNB can configure the configured grant Type 1 using the RRC reconfiguration message. The gNB can configure one or more CG Type 1 configurations. Each configuration can be mapped to one or more TCI states. The TCI state associated with each CG Type configuration can be signaled by the gNB. For UL transmission, the gNB can instruct the UE to use the activated TCI state to determine the UL TX beam. The TCI state can indicate one of SSB / CSI RS. At step S1835, the UE performs UL transmission in the configured CG Type grant associated with the activated TCI state. For UL transmission in this configured grant in CG Type 1, the UE uses the UL TX beam quasi co-located with the RX beam used to receive the SSB / CSI RS of the activated TCI state. For UL transmission in this configured grant of CG Type 1, the UE calculates the PL based on the activated TCI state. Also for example, for CG Type 2 UL grant and dynamic UL grant, the TCI state or SRI used to determine the UL TX beam and PL is indicated in the DCI scheduling those UL grants.

[0715] Figure 20 A flowchart showing a method performed by a user equipment (UE) in a wireless communication system according to an embodiment of the disclosure is shown.

[0716] In some embodiments, a UE can receive, from a base station (BS), a radio resource control (RRC) message including a beam failure detection configuration. For example, the beam failure detection configuration can include a beam failure detection reference signal list, and a TRP indicator in the beam failure detection reference signal list can indicate a TRP associated with each beam failure detection reference signal. For example, the beam failure detection configuration can include at least one beam failure detection reference signal list for each TRP of each BWP of a serving cell. For example, the beam failure detection configuration can be configured for each TRP of the serving cell.

[0717] In some embodiments, the UE can detect, by a physical (PHY) layer, a beam failure of a transmission reception point (TRP) of the serving cell based on the beam failure detection configuration.

[0718] At step S1910, the UE can trigger, by a medium access control (MAC) layer, a beam failure recovery of at least one serving cell.

[0719] At step S1920, the UE can identify, by the MAC layer, whether an evaluation of a candidate beam is completed for at least one serving cell in which the failure recovery is triggered and not cancelled.

[0720] At step S1930, the UE can generate, by the MAC layer, a MAC control element (CE) for the beam failure recovery based on a result of the identification. For example, for at least one serving cell in which the beam failure is detected and the evaluation of the candidate beam is completed, a detection information (i.e., a Ci bit) in the MAC CE is set to 1.

[0721] In some embodiments, the MAC CE can include the detection information indicating whether the beam failure is detected and whether the evaluation of the candidate beam is completed.

[0722] In some embodiments, the detection information can be 1 bit, and in a case that the detection information corresponds to 1, the detection information can indicate that the beam failure is detected and the evaluation of the candidate beam is completed.

[0723] In some embodiments, the UE can receive, from a base station (BS), a radio resource control (RRC) message including a beam failure detection configuration. For example, the beam failure detection configuration can include a beam failure detection reference signal list, and a TRP indicator in the beam failure detection reference signal list can indicate a TRP associated with each beam failure detection reference signal. For example, the beam failure detection configuration can include at least one beam failure detection reference signal list for each TRP of each BWP of a serving cell. For example, the beam failure detection configuration can be configured for each TRP of the serving cell.

[0724] In some embodiments, the UE can start or restart the beam fault detection timer corresponding to the TRP of the serving cell through the MAC layer. Additionally, the UE can update the counter corresponding to the TRP of the serving cell.

[0725] Figure 20 This is a diagram illustrating a UE 2000 according to an embodiment of the present disclosure.

[0726] refer to Figure 20 The UE 2000 may include a processor 2010, a transceiver 2020, and a memory 2030. However, not all of the components shown are necessary. The UE 2000 may be composed of components such as... Figure 21 The implementation can be carried out with more or fewer components. Alternatively, according to another embodiment, the processor 2010, transceiver 2020, and memory 2030 can be implemented as a single chip.

[0727] The above-mentioned components will now be described in detail.

[0728] Processor 2010 may include one or more processors or other processing means that control the provided functions, processes and / or methods. Operation of UE 2000 may be performed by processor 2010.

[0729] Transceiver 2020 can connect to processor 2010 and transmit and / or receive signals. Additionally, transceiver 2020 can receive signals via a wireless channel and output signals to processor 2010. Transceiver 2020 can also transmit signals output from processor 2010 via a wireless channel.

[0730] The memory 2030 may store control information or data included in the signals received by the UE 2000. The memory 2030 may be connected to the processor 2010 and store at least one instruction or protocol or parameter for the provided functions, procedures and / or methods. The memory 2030 may include read-only memory (ROM) and / or random access memory (RAM) and / or hard disk and / or CD-ROM and / or DVD and / or other storage devices.

[0731] Figure 21 This is a diagram illustrating a base station 2100 according to an embodiment of the present disclosure.

[0732] refer to Figure 21 Base station 2100 may include processor 2110, transceiver 2120, and memory 2130. However, not all of the components shown are necessary. Base station 2100 may be composed of... ​ The implementation may involve more or fewer components. Alternatively, according to another embodiment, the processor 2110, transceiver 2120, and memory 2130 may be implemented as a single chip.

[0733] The above-described components will now be described in detail.

[0734] The processor 2110 can include one or more processors or other processing devices that control the provided functions, processes, and / or methods. The operations of the base station 2100 can be implemented by the processor 2110.

[0735] The transceiver 2120 can be connected to the processor 2110 and transmit and / or receive a signal. The signal can include control information and data. In addition, the transceiver 2120 can receive a signal through a wireless channel and output the signal to the processor 2110. The transceiver 2120 can transmit a signal output from the processor 2110 through a wireless channel.

[0736] The memory 2130 can store control information or data included in a signal obtained by the base station 2100. The memory 2130 can be connected to the processor 2110 and store at least one instruction or a protocol or a parameter for the provided functions, processes, and / or methods. The memory 2130 can include read-only memory (ROM) and / or random access memory (RAM) and / or a hard disk and / or a CD-ROM and / or a DVD and / or other storage devices.

[0737] The method according to the claims of the disclosure described in the specification or the various embodiments of the disclosure can be implemented in hardware, software, or a combination of hardware and software.

[0738] When implemented in software, a computer readable storage medium storing one or more programs (software modules) can be provided. The one or more programs stored in the computer readable storage medium are configured for execution by one or more processors in an electronic device. The one or more programs can include instructions that cause the electronic device to perform the methods according to the claims of the disclosure described in the specification or the various embodiments of the disclosure.

[0739] The programs (software modules, software) can be stored in random access memory (RAM), non-volatile memory including a flash memory, read-only memory (ROM), electrically erasable programmable ROM (EEPROM), a magnetic disc storage device, a compact disc-ROM (CD-ROM), a digital versatile disc (DVD), or other types of optical storage devices, and / or a magnetic cassette. Alternatively, the programs can be stored in a memory including a combination of some or all of the memories. There can be a plurality of memories.

[0740] The programs can also be stored in an attachable storage device which can be accessed through a communication network including the Internet, an intranet, a local area network (LAN), a wide area network (WAN), or a storage area network (SAN), or a combination thereof. The storage device can be connected to the device executing various embodiments of the present disclosure through an external port. In addition, a separate storage device in the communication network can be connected to the device executing various embodiments of the present disclosure.

[0741] In various embodiments of the present disclosure, components are expressed in singular or plural form. However, it should be understood that, for convenience of explanation, singular or plural expression is appropriately selected according to the situation presented, and the present disclosure is not limited to singular or plural form of components. In addition, components expressed in plural form can also imply singular form, and vice versa.

[0742] Although the present disclosure has been described with various embodiments, various changes and modifications can be conceived by those skilled in the art. It is intended that the present disclosure encompasses such changes and modifications falling within the scope of the appended claims.

Claims

1. A method performed by a user equipment (UE) in a wireless communication system, the method comprising: Beam Fault Recovery (BFR) of at least one serving cell is triggered via the Media Access Control (MAC) layer, wherein the serving cell is a secondary cell (SCell). The MAC layer is used to identify whether candidate beam evaluation for at least one serving cell where beam fault recovery has been triggered and not canceled has been completed. Based on the completion of the candidate beam evaluation, the MAC control element CE including the Ci field is generated through the MAC layer for beam fault recovery, wherein the Ci field is set to 1 for an SCell with servingCellIndex i that has detected a beam fault and completed the candidate beam evaluation.

2. The method according to claim 1, in, Candidate beams for the at least one serving cell are included in candidateBeamRSSCellList.

3. The method according to claim 1, in, Generating the MAC CE for beam fault recovery includes: If the resources used for the uplink shared channel UL-SCH are available for a new transmission and can accommodate a BFR MAC CE and its sub-headers, then the BFR MAC CE is generated based on the resources used for the UL-SCH; or If the resources used for the uplink shared channel UL-SCH are available for new transmission and can accommodate a truncated BFR MAC CE and its sub-headers, then a truncated BFR MAC CE is generated based on the resources used for the UL-SCH.

4. The method according to claim 3, further comprising: If the resources used for the UL-SCH are unavailable for the MAC CE, a scheduling request for the at least one serving cell is triggered.

5. A user equipment (UE) in a wireless communication system, the UE comprising: transceiver; as well as At least one processor, the at least one processor being coupled to the transceiver and configured to: Beam Fault Recovery (BFR) of at least one serving cell is triggered via the Media Access Control (MAC) layer, wherein the serving cell is a secondary cell (SCell). The MAC layer is used to identify whether candidate beam evaluation for at least one serving cell where beam fault recovery has been triggered and not canceled has been completed. Based on the completion of the candidate beam evaluation, the MAC control element CE including the Ci field is generated through the MAC layer for beam fault recovery, wherein the Ci field is set to 1 for an SCell with servingCellIndex i that has detected a beam fault and completed the candidate beam evaluation.

6. The UE according to claim 5, wherein, Candidate beams for the at least one serving cell are included in candidateBeamRSSCellList.

7. The UE according to claim 5, wherein, The at least one processor is further configured to: If the resources used for the uplink shared channel UL-SCH are available for a new transmission and can accommodate a BFR MAC CE and its sub-headers, then the BFR MAC CE is generated based on the resources used for the UL-SCH; or If the resources used for the uplink shared channel UL-SCH are available for new transmission and can accommodate a truncated BFR MAC CE and its sub-headers, then a truncated BFR MAC CE is generated based on the resources used for the UL-SCH.

8. The UE according to claim 7, wherein, The at least one processor is further configured to: If the resources for the UL-SCH are unavailable for the MAC CE, a scheduling request for the at least one serving cell is triggered.

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