Techniques for handling radio link failure in a wireless communication system

Abstract

In one aspect, the present disclosure includes a method, apparatus, and computer-readable medium for wireless communication at a user equipment (UE), for measuring one or more synchronization signal block (SSB) beams from a network entity; selecting a highest-rated SSB beam from one or more SSB beams based on one or more selection factors; sending a beam report including an identifier of the highest-rated SSB beam to the network entity; starting a timer in response to sending the beam report; determining whether a medium access control (MAC) control element (CE) is received from the network entity before the timer expires; and performing a beam switch from a current SSB beam to the highest-rated SSB beam based on determining that no MAC CE is received from the network entity before the timer expires.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Indian Application No. 201941053677, filed on December 24, 2019, titled “TECHNIQUES FOR HANDLING A RADIOLINK FAILURE IN A WIRELESS COMMUNICATION SYSTEM,” which is assigned to the assignee of the present application and is expressly incorporated herein by reference. Technical Field

[0003] The present disclosure relates generally to communication systems, and more particularly to improved handling of radio link failures in Fifth Generation New Radio (5G NR). Background Art

[0004] Wireless communication systems are widely deployed to provide a variety of telecommunication services, such as telephony, video, data, messaging, and broadcasting. Typical wireless communication systems may employ multiple access technologies capable of supporting communication with multiple users by sharing available system resources. Examples of such multiple access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.

[0005] These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate at a city, country, region, and even global level. An example telecommunication standard is 5G New Radio (NR). 5G NR is part of the continuous mobile broadband evolution promulgated by the Third Generation Partnership Project (3GPP) to meet new requirements associated with latency, reliability, security, scalability (e.g., leveraging the Internet of Things (IoT)), and other requirements. 5G NR includes services associated with enhanced mobile broadband (eMBB), massive machine type communications (mMTC), and ultra-reliable low latency communications (URLLC). Some aspects of 5G NR may be based on the 4G Long Term Evolution (LTE) standard. 5G NR technology requires further improvement. These improvements may also be applicable to other multiple access technologies and telecommunication standards that employ these technologies.

[0006] As the demand for wireless communications continues to grow, so does the desire to increase the efficiency of wireless communications network technologies. Summary of the Invention

[0007] The following presents a simplified overview of one or more aspects in order to provide a basic understanding of these aspects. This overview is not an extensive overview of all contemplated aspects and is neither intended to identify key or critical elements of all aspects nor to delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.

[0008] An example implementation includes a method of wireless communication, comprising: measuring, by a user equipment (UE), one or more synchronization signal block (SSB) beams from a network entity; selecting, by the UE, a highest-rated SSB beam from the one or more SSB beams based on one or more selection factors; sending, by the UE, a beam report including an identifier of the highest-rated SSB beam to the network entity; starting, by the UE, a timer in response to sending the beam report; determining, by the UE, whether a medium access control (MAC) control element (CE) is received from the network entity before expiration of the timer; and performing, by the UE, a beam switch from a current SSB beam to the highest-rated SSB beam based on determining that no MAC CE is received from the network entity before expiration of the timer.

[0009] In another example, an apparatus for wireless communication is provided, comprising: a transceiver; a memory configured to store instructions; and one or more processors communicatively coupled to the transceiver and the memory. The one or more processors are configured to execute the instructions to perform the following operations: measure one or more SSB beams from a network entity; select a highest-ranking SSB beam from the one or more SSB beams based on one or more selection factors; send a beam report including an identification of the highest-ranking SSB beam to the network entity; start a timer in response to sending the beam report; determine whether a MAC CE is received from the network entity before the timer expires; and perform a beam switch from a current SSB beam to the highest-ranking SSB beam based on determining that a MAC CE is not received from the network entity before the timer expires.

[0010] In another aspect, an apparatus for wireless communication is provided, comprising: a component for measuring one or more SSB beams from a network entity; a component for selecting a highest-rated SSB beam from one or more SSB beams based on one or more selection factors; a component for sending a beam report including an identifier of the highest-rated SSB beam to the network entity; a component for starting a timer in response to sending the beam report; a component for determining whether a MAC CE is received from the network entity before the timer expires; and a component for performing a beam switch from a current SSB beam to the highest-rated SSB beam based on determining that a MAC CE is not received from the network entity before the timer expires.

[0011] In another aspect, a non-transitory computer-readable medium is provided, comprising code executable by one or more processors to: measure one or more SSB beams from a network entity; select a highest-rated SSB beam from one or more SSB beams based on one or more selection factors; send a beam report including an identifier of the highest-rated SSB beam to the network entity; start a timer in response to sending the beam report; determine whether a MAC CE is received from the network entity before the timer expires; and perform a beam switch from a current SSB beam to the highest-rated SSB beam based on determining that a MAC CE is not received from the network entity before the timer expires.

[0012] In another example implementation, a method of wireless communication includes: measuring, by a UE, one or more SSB beams from a network entity; selecting, by the UE, a highest-rated SSB beam from the one or more SSB beams based on one or more selection factors; starting, by the UE, a timer in response to selecting the highest-rated SSB beam; determining, by the UE, whether a MAC CE is received from the network entity before the timer expires; sending, by the UE, a request for a radio resource control (RRC) reconfiguration message to the network entity based on determining that no MAC CE is received from the network entity before the timer expires, the RRC reconfiguration message including an identifier of the highest-rated SSB beam; receiving, by the UE, the RRC reconfiguration message from the network entity in response to sending the request; and performing, by the UE, beam switching from a current SSB beam to the highest-rated SSB beam based on the RRC reconfiguration message.

[0013] In another example, an apparatus for wireless communication is provided, comprising: a transceiver; a memory configured to store instructions; and one or more processors communicatively coupled to the transceiver and the memory. The one or more processors are configured to execute the instructions to perform the following operations: measure one or more SSB beams from a network entity; select a highest-ranking SSB beam from the one or more SSB beams based on one or more selection factors; start a timer in response to selecting the highest-ranking SSB beam; determine whether a MAC CE is received from the network entity before the timer expires; based on determining that a MAC CE is not received from the network entity before the timer expires, send a request for an RRC reconfiguration message to the network entity, the RRC reconfiguration message including an identifier of the highest-ranking SSB beam; receive the RRC reconfiguration message from the network entity in response to sending the request; and perform beam switching from a current SSB beam to the highest-ranking SSB beam based on the RRC reconfiguration message.

[0014] In another aspect, an apparatus for wireless communication is provided, comprising: a component for measuring one or more SSB beams from a network entity; a component for selecting a highest-rated SSB beam from one or more SSB beams based on one or more selection factors; a component for starting a timer in response to selecting the highest-rated SSB beam; a component for determining whether a MAC CE is received from the network entity before the timer expires; a component for sending a request for an RRC reconfiguration message to the network entity by a UE based on determining that a MAC CE is not received from the network entity before the timer expires, the RRC reconfiguration message including an identifier of the highest-rated SSB beam; a component for receiving an RRC reconfiguration message from the network entity in response to sending the request; and a component for performing a beam switching from a current SSB beam to the highest-rated SSB beam by the UE based on the RRC reconfiguration message.

[0015] In another aspect, a non-transitory computer-readable medium is provided, comprising code executable by one or more processors to perform the following operations: measuring one or more SSB beams from a network entity; selecting a highest-rated SSB beam from one or more SSB beams based on one or more selection factors; starting a timer in response to selecting the highest-rated SSB beam; determining whether a MAC CE is received from the network entity before the timer expires; based on determining that a MAC CE is not received from the network entity before the timer expires, sending a request for an RRC reconfiguration message to the network entity, the RRC reconfiguration message including an identifier of the highest-rated SSB beam; receiving an RRC reconfiguration message from the network entity in response to sending the request; and performing a beam switch from a current SSB beam to the highest-rated SSB beam based on the RRC reconfiguration message.

[0016] To the accomplishment of the foregoing and related ends, one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the accompanying drawings set forth in detail certain illustrative features of one or more aspects. However, these features are indicative of but a few of the various ways in which the principles of the various aspects may be employed, and this description is intended to include all such aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a diagram illustrating an example of a wireless communication system and an access network.

[0018] Figure 2A 、 2B , 2C, and 2D are diagrams illustrating examples of a first 5G / NR frame, a DL channel within a 5G / NR subframe, a second 5G / NR frame, and a UL channel within a 5G / NR subframe, respectively.

[0019] Figure 3 is a diagram illustrating an example of a base station and a user equipment (UE) in an access network.

[0020] Figure 4 is a diagram illustrating a message flow between a UE and a network entity corresponding to a Medium Access Control (MAC) Control Element (CE) Down Selection (DS) procedure.

[0021] Figure 5 is a diagram illustrating a radio link failure (RLF) at a UE due to the absence of a MAC CE.

[0022] Figure 6 The present invention is a flowchart of a method of wireless communication, and more specifically, a flowchart of a method for performing beam switching by a UE based on a MAC CE wait timer.

[0023] Figure 7 The present invention is a flowchart of a method of wireless communication, and more particularly, a flowchart of a method of performing beam switching by a UE based on a radio resource control (RRC) reconfiguration message.

[0024] Figure 8 is a block diagram illustrating an example of a UE according to various aspects of the present disclosure.

[0025] Figure 9 is a block diagram illustrating an example of a base station according to various aspects of the present disclosure. DETAILED DESCRIPTION

[0026] The detailed description set forth below in conjunction with the accompanying drawings is intended as a description of various configurations and is not intended to represent the only configuration in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of the various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some cases, well-known structures and components are shown in block diagram form to avoid obscuring these concepts.

[0027] Several aspects of telecommunications systems will now be presented with reference to various apparatuses and methods. These apparatuses and methods will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, components, circuits, processes, algorithms, etc. (collectively, "elements"). These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system.

[0028] For example, an element, or any part of an element, or any combination of elements can be implemented as a "processing system" comprising one or more processors. Examples of processors include microprocessors, microcontrollers, graphics processing units (GPUs), central processing units (CPUs), application processors, digital signal processors (DSPs), reduced instruction set computing (RISC) processors, systems on a chip (SoCs), baseband processors, field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gating logic, discrete hardware circuits, and other suitable hardware configured to perform the various functions described throughout this disclosure. One or more processors in a processing system can execute software. Whether it involves software, firmware, middleware, microcode, hardware description language or other, software should be broadly interpreted as representing instructions, instruction sets, codes, code segments, program codes, programs, subroutines, software components, applications, software applications, software packages, routines, subroutines, objects, executable files, execution threads, processes, functions, etc.

[0029] Therefore, in one or more example embodiments, the functions described can be implemented in hardware, software, or any combination thereof. If implemented in software, the functions can be stored on a computer-readable medium, or encoded as one or more instructions or codes on a computer-readable medium. Computer-readable media include computer storage media. The storage medium can be any available medium that can be accessed by a computer. As an example and not limitation, such computer-readable media can include random access memory (RAM), read-only memory (ROM), electrically erasable programmable ROM (EEPROM), optical disk storage, magnetic disk storage, other magnetic storage devices, a combination of the aforementioned types of computer-readable media, or any other medium that can be used to store computer-executable code in the form of instructions or data structures that can be accessed by a computer.

[0030] Figure 1 The present invention is a diagram illustrating an example of a wireless communication system and access network 100 configured for improved handling of radio link failure (RLF) in fifth generation new radio (5G NR). The wireless communication system (also known as a wireless wide area network (WWAN)) includes a base station 102, a UE 104, an evolved packet core (EPC) 160, and another core network 190 (e.g., a 5G core (5GC)).

[0031] In certain aspects, the UE 104 may be configured to operate the communication component 198 and / or the configuration component 240 to perform the following operations: measure one or more synchronization signal block (SSB) beams from a network entity; select a highest-rated SSB beam from the one or more SSB beams based on one or more selection factors; send a beam report to the network entity that includes an identifier of the highest-rated SSB beam; start a timer in response to sending the beam report; determine whether a medium access control (MAC) control element (CE) is received from the network entity before the timer expires; and perform a beam switch from a current SSB beam to the highest-rated SSB beam based on determining that a MAC CE is not received from the network entity before the timer expires.

[0032] On the other hand, the UE 104 may be configured to operate the communication component 198 and / or the configuration component 240 to perform the following operations: measure one or more SSB beams from a network entity; select a highest-rated SSB beam from one or more SSB beams based on one or more selection factors; start a timer in response to selecting the highest-rated SSB beam; determine whether a MAC CE is received from the network entity before the timer expires; based on determining that a MAC CE is not received from the network entity before the timer expires, send a request for a radio resource control (RRC) reconfiguration message to the network entity, the RRC reconfiguration message including an identifier of the highest-rated SSB beam; receive the RRC reconfiguration message from the network entity in response to sending the request; and perform beam switching from the current SSB beam to the highest-rated SSB beam based on the RRC reconfiguration message.

[0033] Thus, in certain aspects, a network entity 102 (e.g., a base station) and / or another UE (such as UE 104) can be configured to operate a communication component 199 and / or a configuration component 241 to communicate with the UE 104, e.g., to engage in a handshake process. For example, the communication component 199 and / or the configuration component 241 can transmit one or more SSB beams to one or more UEs 104.

[0034] Base stations 102 may include macro cells (high-power cellular base stations) and / or small cells (low-power cellular base stations). Macro cells include base stations. Small cells include femto cells, pico cells, and micro cells.

[0035] Base stations 102 configured for 4G LTE (collectively referred to as the Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) may interface with the EPC 160 via a backhaul link 132 (e.g., an S1 interface). Base stations 102 configured for 5G NR (collectively referred to as the Next Generation RAN (NG-RAN)) may interface with the core network 190 via a backhaul link 184. The base stations 102 may perform one or more of the following functions, among other things: transmission of user data, radio channel encryption and decryption, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection establishment and release, load balancing, distribution of non-access stratum (NAS) messages, NAS node selection, synchronization, radio access network (RAN) sharing, multimedia broadcast multicast service (MBMS), subscriber and device tracking, RAN information management (RIM), paging, positioning, and delivery of warning messages. Base stations 102 may communicate with each other via backhaul links 134 (eg, an X2 interface) directly or indirectly (eg, via EPC 160 or core network 190). Backhaul links 132, 134, and 184 may be wired or wireless.

[0036] Base stations 102 can communicate wirelessly with UEs 104. Each of base stations 102 can provide communication coverage for a corresponding geographic coverage area 110. There may be overlapping geographic coverage areas 110. For example, a small cell 102′ can have a coverage area 110′ that overlaps with the coverage area 110 of one or more macro base stations 102. A network that includes both small cells and macro cells may be referred to as a heterogeneous network. A heterogeneous network may also include a Home Evolved Node B (eNB) (HeNB), which may provide service to a restricted group known as a Closed Subscriber Group (CSG). The communication link 120 between base station 102 and UE 104 may include uplink (UL) (also known as reverse link) transmissions from UE 104 to base station 102 and / or downlink (DL) (also known as forward link) transmissions from base station 102 to UE 104. The communication link 120 may use multiple-input multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and / or transmit diversity. The communication link may be over one or more carriers. Base station 102 / UE 104 can use up to Y MHz (e.g., 5, 10, 15, 20, 100, 400, etc. MHz) of bandwidth per carrier allocated in carrier aggregation for a total of up to Yx MHz (x component carriers) for transmission in each direction. The carriers may be adjacent to each other or may not be adjacent to each other. The allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated for DL ​​compared to UL). Component carriers may include a primary component carrier and one or more secondary component carriers. The primary component carrier may be referred to as a primary cell (PCell), and the secondary component carrier may be referred to as a secondary cell (SCell).

[0037] Certain UEs 104 may communicate with each other using device-to-device (D2D) communication links 158. The D2D communication links 158 may use the DL / UL WWAN spectrum. The D2D communication links 158 may use one or more sidelink channels, such as a physical sidelink broadcast channel (PSBCH), a physical sidelink discovery channel (PSDCH), a physical sidelink shared channel (PSSCH), and a physical sidelink control channel (PSCCH). D2D communication may be performed via various wireless D2D communication systems, such as FlashLinQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based on the IEEE 802.11 standard, LTE, or NR.

[0038] The wireless communication system may also include a Wi-Fi access point (AP) 150 that communicates with a Wi-Fi station (STA) 152 in the 5 GHz unlicensed spectrum via a communication link 154. When communicating in the unlicensed spectrum, the STA 152 / AP 150 may perform a clear channel assessment (CCA) prior to communication to determine whether the channel is available.

[0039] Small cell 102' can operate in licensed and / or unlicensed spectrum. When operating in the unlicensed spectrum, small cell 102' can employ NR and use the same 5 GHz unlicensed spectrum used by Wi-Fi AP 150. Small cell 102' employing NR in the unlicensed spectrum can improve coverage and / or increase capacity of the access network.

[0040] Whether a small cell 102' or a large cell (e.g., a macro base station), base station 102 may comprise an eNB, a gNodeB (gNB), or another type of base station. Some base stations, such as gNB 180, may operate in traditional sub-6 GHz spectrum, millimeter wave (mmW) frequencies, and / or near-mmW frequencies to communicate with UE 104. When gNB 180 operates in mmW or near-mmW frequencies, gNB 180 may be referred to as a mmW base station. Extremely high frequency (EHF) is a portion of the RF spectrum in the electromagnetic spectrum. EHF ranges from 30 GHz to 300 GHz and has wavelengths between 1 mm and 10 mm. Radio waves in this band may be referred to as millimeter waves. Near-mmW extends down to frequencies of 3 GHz, with wavelengths of 100 mm. Super high frequency (SHF) bands extend between 3 GHz and 30 GHz and are also referred to as centimeter waves. Communications using mmW / near-mmW radio frequency bands (e.g., 3 GHz to 300 GHz) suffer from extremely high path loss and short range. The mmW base station 180 may utilize beamforming 182 with the UE 104 to compensate for the extremely high path loss and short range.

[0041] Base station 180 may transmit beamformed signals in one or more transmit directions 182′ to UE 104. UE 104 may receive beamformed signals from base station 180 in one or more receive directions 182″. UE 104 may also transmit beamformed signals in one or more transmit directions to base station 180. Base station 180 may receive beamformed signals in one or more receive directions from UE 104. Base station 180 / UE 104 may perform beam training to determine optimal receive and transmit directions for each of base station 180 / UE 104. The transmit and receive directions of base station 180 may or may not be the same. The transmit and receive directions of UE 104 may or may not be the same.

[0042] The EPC 160 may include a Mobility Management Entity (MME) 162, other MMEs 164, a Serving Gateway 166, a Multimedia Broadcast Multicast Service (MBMS) Gateway 168, a Broadcast Multicast Service Center (BM-SC) 170, and a Packet Data Network (PDN) Gateway 172. The MME 162 may communicate with a Home Subscriber Server (HSS) 174. The MME 162 is a control node that handles signaling between the UE 104 and the EPC 160. Generally, the MME 162 provides bearer and connection management. All user Internet Protocol (IP) packets are transmitted through the Serving Gateway 166, which itself is connected to the PDN Gateway 172. The PDN Gateway 172 provides UE IP address allocation and other functions. The PDN Gateway 172 and the BM-SC 170 are connected to the IP Services 176. The IP Services 176 may include the Internet, an intranet, an IP Multimedia Subsystem (IMS), PS streaming services, and / or other IP services. The BM-SC 170 may provide functionality for MBMS user service provisioning and delivery. The BM-SC 170 may serve as the entry point for content providers' MBMS transmissions, may be used to authorize and initiate MBMS bearer services within a public land mobile network (PLMN), and may be used to schedule MBMS transmissions. The MBMS Gateway 168 may be used to distribute MBMS services to base stations 102 belonging to a Multicast Broadcast Single Frequency Network (MBSFN) area broadcasting a specific service, and may be responsible for session management (start / stop) and collecting eMBMS-related billing information.

[0043] The core network 190 may include an access and mobility management function (AMF) 192, other AMFs 193, a session management function (SMF) 194, and a user plane function (UPF) 195. The AMF 192 may communicate with a unified data management (UDM) 196. The AMF 192 is a control node that handles signaling between the UE 104 and the core network 190. Typically, the AMF 192 provides QoS flow and session management. All user Internet Protocol (IP) packets are transmitted through the UPF 195. The UPF 195 provides UE IP address allocation and other functions. The UPF 195 is connected to the IP services 197. The IP services 197 may include the Internet, an intranet, an IP multimedia subsystem (IMS), PS streaming services, and / or other IP services.

[0044] A base station may also be referred to as a gNB, a Node B, an evolved Node B (eNB), an access point, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), a transmit reception point (TRP), or some other suitable terminology. Base station 102 provides an access point to EPC 160 or core network 190 for UE 104. Examples of UE 104 include a cellular phone, a smartphone, a Session Initiation Protocol (SIP) phone, a laptop, a personal digital assistant (PDA), a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., an MP3 player), a camera, a game console, a tablet, a smart device, a wearable device, a vehicle, an electric meter, a gas pump, a large or small kitchen appliance, a healthcare device, an implant, a sensor / actuator, a display, or any other similarly functional device. Some of UE 104 may be referred to as IoT devices (e.g., a parking meter, a gas pump, a toaster, a vehicle, a heart monitor, etc.). UE 104 may also be referred to as a station, a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communication device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology.

[0045] Figures 2A-2D Included are diagrams of example frame structures and resources that may be used in communications between base station 102, UE 104, and / or assisting UE (or sidelink UE) 110 as described in this disclosure. Figure 2A FIG200 is a diagram illustrating an example of a first subframe within a 5G / NR frame structure. Figure 2B FIG230 is a diagram illustrating an example of DL channels within a 5G / NR subframe. Figure 2C Figure 250 illustrates an example of a second subframe within a 5G / NR frame structure. Figure 2D 280 is a diagram illustrating an example of UL channels within a 5G / NR subframe. The 5G / NR frame structure may be FDD, where for a particular set of subcarriers (carrier system bandwidth), subframes within that subcarrier set are dedicated to either DL or UL, or TDD, where for a particular set of subcarriers (carrier system bandwidth), subframes within that subcarrier set are dedicated to both DL and UL. Figure 2A 、 2CIn the example provided, it is assumed that the 5G / NR frame structure is TDD, subframe 4 is configured with time slot format 28 (primarily DL), where D is DL, U is UL, and X is flexible between DL / UL, and subframe 3 is configured with time slot format 34 (primarily UL). Although subframes 3 and 4 are shown with time slot formats 34 and 28 respectively, any particular subframe can be configured with any of the various available time slot formats 0-61. Time slot formats 0 and 1 are DL and UL respectively. Other time slot formats 2-61 include a mix of DL, UL and flexible symbols. The UE is configured with the time slot format via a received time slot format indicator (SFI) (dynamically via DL control information (DCI), or semi-statically / statically via radio resource control (RRC) signaling). Note that the description of "infrastructure (infra)" also applies to the 5G / NR frame structure for TDD.

[0046] Other wireless communication technologies may have different frame structures and / or different channels. A frame (10ms) may be divided into 10 equally sized subframes (1ms). Each subframe may include one or more time slots. A subframe may also include a microslot, which may include 7, 4, or 2 symbols. Depending on the time slot configuration, each time slot may contain 7 or 14 symbols. For time slot configuration 0, each time slot may include 14 symbols, and for time slot configuration 1, each time slot may include 7 symbols. The symbols on the DL may be cyclic prefix (CP) OFDM (CP-OFDM) symbols. The symbols on the UL may be CP-OFDM symbols (for high throughput scenarios) or discrete Fourier transform (DFT) spread OFDM (DFT-s-OFDM) symbols (also known as single carrier frequency division multiple access (SC-FDMA) symbols) (for power-limited scenarios; limited to single stream transmission). The number of time slots within a subframe is based on the time slot configuration and parameter set (numerology). For slot configuration 0, different parameter sets μ from 0 to 5 allow 1, 2, 4, 8, 16, and 32 slots per subframe, respectively. For slot configuration 1, different parameter sets from 0 to 2 allow 2, 4, and 8 slots per subframe, respectively. Therefore, for slot configuration 0 and parameter set μ, there are 14 symbols / slot and 2 μ time slots / subframes. The subcarrier spacing and symbol length / duration are functions of the parameter set. The subcarrier spacing can be equal to 2 μ *15kHz, where μ is parameter set 0 to 5. Thus, parameter set μ=0 has a subcarrier spacing of 15kHz, and parameter set μ=5 has a subcarrier spacing of 480kHz. The symbol length / duration is inversely related to the subcarrier spacing. Figures 2A-2DAn example is provided for slot configuration 0 with 14 symbols per slot and parameter set μ = 0 with 1 slot per subframe. The subcarrier spacing is 15 kHz and the symbol duration is approximately 66.7 μs.

[0047] The resource grid can be used to represent the frame structure. Each time slot includes a resource block (RB) (also called a physical RB (PRB)) that extends over 12 consecutive subcarriers. The resource grid is divided into multiple resource elements (REs). The number of bits carried by each RE depends on the modulation scheme.

[0048] like Figure 2A As shown, some of the REs carry reference (pilot) signals (RS) for the UE. The RSs may include demodulation RSs (DM-RSs) (denoted as R for a specific configuration where 100x is the port number). x , but other DM-RS configurations are possible) and a channel state information reference signal (CSI-RS) for channel estimation at the UE. The RS may also include a beam measurement RS (BRS), a beam refinement RS (BRRS), and a phase tracking RS (PT-RS).

[0049] Figure 2B The diagram illustrates examples of various DL channels within a subframe of a frame. The physical downlink control channel (PDCCH) carries DCI within one or more control channel elements (CCEs), each CCE including nine RE groups (REGs), and each REG including four consecutive REs in an OFDM symbol. The primary synchronization signal (PSS) can be within symbol 2 of a specific subframe of the frame. The UE 104 uses the PSS to determine the subframe / symbol timing and the physical layer identity. The secondary synchronization signal (SSS) can be within symbol 4 of a specific subframe of the frame. The UE uses the SSS to determine the physical layer cell identity group number and the radio frame timing. Based on the physical layer identity and the physical layer cell identity group number, the UE can determine the physical cell identifier (PCI). Based on the PCI, the UE can determine the position of the aforementioned DM-RS. The physical broadcast channel (PBCH) carrying the master information block (MIB) can be logically grouped using the PSS and SSS to form a synchronization signal (SS) / PBCH block. The MIB provides multiple RBs in the system bandwidth and the system frame number (SFN). The Physical Downlink Shared Channel (PDSCH) carries user data, broadcast system information such as System Information Blocks (SIBs) that are not transmitted through the PBCH, and paging messages.

[0050] like Figure 2CAs shown, some of the REs carry DM-RSs for channel estimation at the base station (indicated as R for one specific configuration, but other DM-RS configurations are possible). The UE can send DM-RSs for the physical uplink control channel (PUCCH) and DM-RSs for the physical uplink shared channel (PUSCH). The PUSCH DM-RS can be sent in the first one or two symbols of the PUSCH. Depending on whether a short PUCCH or a long PUCCH is sent, and depending on the specific PUCCH format used, the PUCCH DM-RS can be sent in different configurations. Although not shown, the UE can send a sounding reference signal (SRS). The base station can use this SRS for channel quality estimation to enable frequency-dependent scheduling on the UL.

[0051] Figure 2D The figure illustrates examples of various UL channels within a subframe of a frame. The PUCCH may be positioned as indicated in a configuration. The PUCCH carries uplink control information (UCI), such as scheduling requests, channel quality indicators (CQI), precoding matrix indicators (PMI), rank indicators (RI), and HARQ ACK / NACK feedback. The PUSCH carries data and may additionally be used to carry buffer status reports (BSRs), power headroom reports (PHRs), and / or UCI.

[0052] Figure 33 is a block diagram of a base station 310 communicating with a UE 350 in an access network, where the base station 310 may be an example implementation of the base station 102, and where the UE 350 may be an example implementation of the UE 104. In the DL, IP packets from the EPC 160 may be provided to a controller / processor 375. The controller / processor 375 implements layer 3 and layer 2 functionality. Layer 3 includes a radio resource control (RRC) layer, and layer 2 includes a service data adaptation protocol (SDAP) layer, a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, and a medium access control (MAC) layer. The controller / processor 375 provides RRC layer functions associated with broadcasting of system information (e.g., MIB, SIB), RRC connection control (e.g., RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release), inter-radio access technology (RAT) mobility, and measurement configuration for UE measurement reporting; PDCP layer functions associated with header compression / decompression, security (ciphering, deciphering, integrity protection, integrity verification), and handover support functions; RLC layer functions associated with transmission of upper layer packet data units (PDUs), error correction through ARQ, concatenation, segmentation and reassembly of RLC service data units (SDUs), resegmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functions associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs to transport blocks (TBs), demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

[0053] The transmit (TX) processor 316 and receive (RX) processor 370 implement Layer 1 functions associated with various signal processing functions. Layer 1, including the physical (PHY) layer, may include error detection on the transport channel, forward error correction (FEC) encoding / decoding of the transport channel, interleaving, rate matching, mapping onto the physical channel, modulation / demodulation of the physical channel, and MIMO antenna processing. The TX processor 316 handles the mapping to the signal constellation based on various modulation schemes (e.g., binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), M-phase shift keying (M-PSK), M-quadrature amplitude modulation (M-QAM)). The coded and modulated symbols can then be split into parallel streams. Each stream can then be mapped to an OFDM subcarrier, multiplexed with a reference signal (e.g., a pilot) in the time and / or frequency domain, and then combined using an inverse fast Fourier transform (IFFT) to produce a physical channel carrying a time-domain OFDM symbol stream. The OFDM stream is spatially precoded to produce multiple spatial streams. Channel estimates from a channel estimator 374 may be used to determine coding and modulation schemes, as well as for spatial processing. The channel estimates may be derived from a reference signal and / or channel condition feedback transmitted by the UE 350. Each spatial stream may then be provided to a different antenna 320 via a separate transmitter 318TX. Each transmitter 318TX may modulate an RF carrier with a corresponding spatial stream for transmission.

[0054] At the UE 350, each receiver 354RX receives a signal through its corresponding antenna 352. Each receiver 354RX recovers the information modulated onto the RF carrier and provides the information to a receive (RX) processor 356. The TX processor 368 and the RX processor 356 implement layer 1 functions associated with various signal processing functions. The RX processor 356 can perform spatial processing on the information to recover any spatial streams destined for the UE 350. If multiple spatial streams are destined for the UE 350, they can be combined into a single OFDM symbol stream by the RX processor 356. The RX processor 356 then converts the OFDM symbol stream from the time domain to the frequency domain using a fast Fourier transform (FFT). The frequency domain signal includes a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier and the reference signal are recovered and demodulated by determining the most likely signal constellation point sent by the base station 310. These soft decisions can be based on the channel estimates calculated by the channel estimator 358. The soft decisions are then decoded and deinterleaved to recover the data and control signals originally sent on the physical channel by base station 310. The data and control signals are then provided to a controller / processor 359, which implements layer 3 and layer 2 functionality.

[0055] The controller / processor 359 may be associated with a memory 360 that stores program codes and data. The memory 360 may be referred to as a computer-readable medium. In the UL, the controller / processor 359 provides demultiplexing between transport and logical channels, packet reassembly, decryption, header decompression, and control signal processing to recover IP packets from the EPC 160. The controller / processor 359 is also responsible for error detection using an ACK and / or NACK protocol to support HARQ operations.

[0056] Similar to the functions described in conjunction with the DL transmission of the base station 310, the controller / processor 359 provides RRC layer functions associated with system information (e.g., MIB, SIB) acquisition, RRC connection, and measurement reporting; PDCP layer functions associated with header compression / decompression, and security (encryption, decryption, integrity protection, integrity checking); RLC layer functions associated with transmission of upper layer PDUs, error correction through ARQ, concatenation, segmentation, and reassembly of RLC SDUs, resegmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functions associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs to TBs, demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel priority.

[0057] The TX processor 368 may select an appropriate coding and modulation scheme and facilitate spatial processing using channel estimates derived by the channel estimator 358 from a reference signal or feedback transmitted by the base station 310. The spatial streams generated by the TX processor 368 may be provided to different antennas 352 via separate transmitters 354TX. Each transmitter 354TX may modulate an RF carrier with a corresponding spatial stream for transmission.

[0058] At the base station 310, the UL transmission is processed in a manner similar to that described in conjunction with the receiver functionality at the UE 350. Each receiver 318RX receives a signal through its respective antenna 320. Each receiver 318RX recovers information modulated onto an RF carrier and provides the information to an RX processor 370.

[0059] The controller / processor 375 may be associated with a memory 376 that stores program codes and data. The memory 376 may be referred to as a computer-readable medium. In the UL, the controller / processor 375 provides demultiplexing between transport and logical channels, packet reassembly, decryption, header decompression, and control signal processing to recover IP packets from the UE 350. The IP packets from the controller / processor 375 may be provided to the EPC 160. The controller / processor 375 is also responsible for error detection using an ACK and / or NACK protocol to support HARQ operations.

[0060] At least one of the TX processor 368, the RX processor 356, and the controller / processor 359 may be configured to perform operations related to Figure 1 Various aspects related to the communication component 198.

[0061] At least one of the TX processor 316, the RX processor 370, and the controller / processor 375 may be configured to perform operations related to Figure 1 Various aspects related to the communication component 199.

[0062] refer to Figure 4-Figure 9 , the described features generally relate to improved handling of radio link failure (RLF) in fifth generation new radio (5G NR). For example, in 5G NR, larger antenna array sizes are used to achieve adequate network coverage and connectivity to one or more UEs established through a serving beam (e.g., serving SSB). In some instances, the network may direct the UE to have a beam switch change from a current SSB X to a new SSB Y. The UE may request the network to perform a beam switch only through a random access channel (RACH) attempt or a periodic beam report. The network may decide based on the beam report and / or RACH attempt from the UE and may send a radio resource control (RRC) reconfiguration or a medium access control (MAC) control element (CE) down select to have a beam switch. Due to the expected higher path and Doppler effects in mmW, beam switching is required to maintain proper connectivity and / or improve data throughput.

[0063] In one aspect, during connection establishment, the UE and the network can establish a gNB serving SSB Tx to UE Rx beam pair. In some examples, when the UE is mobile, the UE may not observe the highest reference signal received power (RSRP) from the previous serving gNB SSB TX beam. The UE can determine the best RSRP from neighboring SSB TX beams (e.g., the virtual serving SSB (VSSSB) of the same gNB). Therefore, a two-way handshake mechanism is required between the gNB and the UE to establish the next best beam pair link with the VSSSB and UE RX beams. During the handshake process, the UE can measure the SSB TX beams with the RX beams and report them to the gNB.

[0064] In one aspect, some networks may not support MAC CE in certain countries. However, in order to maintain connectivity, this issue needs to be addressed in order to prevent a large number of call drops and / or RLFs that result in a poor user experience.

[0065] The present disclosure generally relates to current issues in handling RLF in 5GNR. For example, in one aspect, the present disclosure includes a method, apparatus, and non-transitory computer-readable medium for wireless communication for measuring, by a UE, one or more SSB beams from a network entity; selecting, by the UE, a highest-ranking SSB beam from the one or more SSB beams based on one or more selection factors; sending, by the UE, a beam report including an identification of the highest-ranking SSB beam to the network entity; starting, by the UE, a timer in response to sending the beam report; determining, by the UE, whether a MAC CE is received from the network entity before expiration of the timer; and performing, by the UE, a beam switch from a current SSB beam to the highest-ranking SSB beam based on determining that a MAC CE is not received from the network entity before expiration of the timer.

[0066] In another example, the present disclosure includes a method, apparatus, and non-transitory computer-readable medium for wireless communication, for measuring, by a UE, one or more SSB beams from a network entity; selecting, by the UE, a highest-rated SSB beam from one or more SSB beams based on one or more selection factors; starting, by the UE, a timer in response to selecting the highest-rated SSB beam; determining, by the UE, whether a MAC CE is received from the network entity before the timer expires; sending, by the UE, a request for a radio resource control (RRC) reconfiguration message to the network entity based on determining that no MAC CE is received from the network entity before the timer expires, the RRC reconfiguration message including an identifier of the highest-rated SSB beam; receiving, by the UE, the RRC reconfiguration message from the network entity in response to sending the request; and performing, by the UE, beam switching from a current SSB beam to the highest-rated SSB beam based on the RRC reconfiguration message.

[0067] Figure 4Figure 400 illustrates a message flow between a UE and network entities corresponding to a Medium Access Control (MAC) Control Element (CE) Down Selection (DS) procedure. For example, diagram 400 illustrates a message flow for gNB 402 determining that UE 404 is considering beam switching. In step 1, gNB 402 may perform RRC serving cell static configuration. In step 2, gNB 402 may send a serving cell common and dedicated CFG request for RRC serving cell static configuration. In step 3, gNB 402 may perform beam reporting, and at step 4, UE 404 may send a beam report to gNB 402. In step 5, PDSCH down selection occurs between gNB 402 and UE 404. For example, in step 6, gNB 402 may send a MAC CE Down Selection message associated with the PDCCH and PDSCH to UE 404. In step 7, due to insufficient quasi-co-located (QCL) link with gNB 402, the UE may perform autonomous beam switching.

[0068] Figure 5 Figure 500 illustrates a radio link failure (RLF) occurring at a UE due to the absence of a MAC CE. For example, the gNB can send a MAC CE beam switch command to the UE. However, if the network does not support serving gNB Tx beam (e.g., SSB beam) switching via MAC CE, or even after waiting for a MAC CE from the network when beam failure detection occurs or beam failure recovery has begun, numerous issues can occur during initial deployment. In some instances, the UE may remain fixed on the current serving SSB beam even if the UE changes location and does not measure the maximum LL-RSRP in the VSSSB TX beam. In some cases, throughput may be reduced. In some instances, beam switching in the absence of a MAC CE may result in RLF failure and occupancy on the VSSSB. In this example, diagram 500 illustrates the UE being served by serving SSB 0. When the UE moves without receiving a MAC CE, the serving SSB remains SSB 0. However, as the UE moves far enough, it begins to observe weak power from SSB 0, which can lead to RLF and poor throughput.

[0069] Figure 6600 is a flow chart of a method of wireless communication, and more particularly, a flow chart of a method for a UE to perform beam switching based on a MAC CE wait timer. The method may be performed by a UE (e.g., UE 104, apparatus 350, controller / processor 359 (which may include memory 360), processor(s) 512 (which may include memory 516, modem 540, and which may be the entire UE 104 or a component of the UE 104, such as TX processor 368, RX processor 356, and / or transceiver 502) in conjunction with communication component 198 / configuration component 240.

[0070] At 602, method 600 includes measuring, by the UE, one or more SSB beams from a network entity. In an aspect, the UE 104 and / or the communication component 198 / configuration component 240 can be configured to measure one or more SSB beams from the network entity. Thus, the UE 104 and / or the communication component 198 / configuration component 240 (e.g., in conjunction with the controller / processor 359 (which may include memory 360), the processor(s) 512 (which may include memory 516), the modem 540, the TX processor 368, and the transceiver 502) can define means for measuring, by the UE, one or more SSB beams from the network entity.

[0071] In an example of method 600, UE 104 and / or communication component 198 / configuration component 240 configured to measure one or more SSB beams further includes measuring a corresponding reference signal received power (RSRP) for each of the one or more SSB beams.

[0072] In an example of method 600, the UE 104 and / or the communication component 198 / configuration component 240 configured to measure one or more SSB beams also includes measuring one or more neighbor SSB transmit beams paired with the one or more receive beams at the current location of the UE. For example, the one or more neighbor SSB transmit beams correspond to virtual service SSB (VS SSB) beams.

[0073] At 604, method 600 includes selecting, by the UE, a highest-ranking SSB beam from the one or more SSB beams based on one or more selection factors. In an aspect, the UE 104 and / or the communication component 198 / configuration component 240 can be configured to select the highest-ranking SSB beam from the one or more SSB beams based on the one or more selection factors. Thus, the UE 104 and / or the communication component 198 / configuration component 240 (e.g., in conjunction with the controller / processor 359 (which may include memory 360), the processor(s) 512 (which may include memory 516), the modem 540, the RX processor 356, and the transceiver 502) can define means for selecting, by the UE, the highest-ranking SSB beam from the one or more SSB beams based on the one or more selection factors.

[0074] In an example of method 600, the one or more selection factors include a physical broadcast channel (PBCH) cyclic redundancy check (CRC) threshold.

[0075] In an example of method 600, UE 104 and / or communication component 198 / configuration component 240 configured to select a highest-ranking SSB beam further includes selecting a highest-ranking SSB beam from one or more SSB beams using a corresponding PBCH CRC that satisfies a PBCH CRC threshold.

[0076] In an example of method 600, the UE 104 and / or communication component 198 / configuration component 240 configured to select a highest-ranking SSB beam from one or more SSB beams also includes ranking corresponding RSRPs for each of the one or more SSB beams, wherein the RSRP of an SSB beam having the highest average power among the one or more SSB beams corresponds to the highest-ranking SSB beam.

[0077] At 606, method 600 includes sending, by the UE, to a network entity, a beam report that includes an identification of the highest-rated SSB beam. In an aspect, UE 104 and / or communication component 198 / configuration component 240 can be configured to send, to the network entity, a beam report that includes an identification of the highest-rated SSB beam. Thus, UE 104 and / or communication component 198 / configuration component 240 (e.g., in conjunction with controller / processor 359 (which can include memory 360), processor(s) 512 (which can include memory 516), modem 540, RX processor 356, and transceiver 502) can define means for sending, by the UE, to the network entity, a beam report that includes an identification of the highest-rated SSB beam.

[0078] At 608, method 600 includes starting, by the UE, a timer in response to transmitting the beam report. In one aspect, UE 104 and / or communication component 198 / configuration component 240 can be configured to start a timer in response to transmitting the beam report. Thus, UE 104 and / or communication component 198 / configuration component 240 (e.g., in conjunction with communication component 198 / configuration component 240) can be configured to perform the following operations: controller / processor 359 (which can include memory 360), processor(s) 512 (which can include memory 516), modem 540, RX processor 356, and transceiver 502 can define means for starting a timer in response to transmitting the beam report by the UE.

[0079] At 610, method 600 includes determining, by the UE, whether a MAC CE is received from the network entity before the expiration of the timer. In one aspect, the UE 104 and / or the communication component 198 / configuration component 240 can be configured to determine whether a MAC CE is received from the network entity before the expiration of the timer. Thus, the UE 104 and / or the communication component 198 / configuration component 240 (e.g., in conjunction with the controller / processor 359 (which may include memory 360), the processor(s) 512 (which may include memory 516), the modem 540, the RX processor 356, and the transceiver 502) can define means for determining, by the UE, whether a MAC CE is received from the network entity before the expiration of the timer. In an example, the MAC CE is associated with a down selection.

[0080] In an example of method 600, the UE 104 and / or communication component 198 / configuration component 240 configured to determine whether a MAC CE is received from a network entity before the timer expires also includes determining that a MAC CE is received from the network entity on a physical downlink shared channel (PDSCH) or a physical downlink control channel (PDCCH) before the timer expires.

[0081] At 612, method 600 includes performing, by the UE, a beam switch from a current SSB beam to a highest-ranking SSB beam based on determining that a MAC CE was not received from the network entity before expiration of a timer. In an aspect, the UE 104 and / or the communication component 198 / configuration component 240 may be configured to perform a beam switch from the current SSB beam to the highest-ranking SSB beam based on determining that a MAC CE was not received from the network entity before expiration of the timer. Thus, the UE 104 and / or the communication component 198 / configuration component 240 (e.g., in conjunction with the controller / processor 359 (which may include memory 360), the processor(s) 512 (which may include memory 516), the modem 540, the RX processor 356, and the transceiver 502) may define means for performing, by the UE, a beam switch from the current UE to the highest-ranking SSB beam based on determining that a MAC CE was not received from the network entity before expiration of the timer.

[0082] In an example of method 600, the UE 104 and / or communication component 198 / configuration component 240 configured to perform beam switching from a current SSB beam to a highest-rated SSB beam is further based on determining that a beam failure detection or beam failure recovery procedure has not been initiated before expiration of a second timer.

[0083] Figure 7 700 is a flow chart of a method of wireless communication, and more specifically, a flow chart of a method of beam switching by a UE based on a radio resource control (RRC) reconfiguration message. The method may be performed by a UE (e.g., UE 104, apparatus 350, controller / processor 359 (which may include memory 360), processor(s) 512 (which may include memory 516), modem 540, which may be the entire UE 104 or a component of the UE 104, such as TX processor 368, RX processor 356, and / or transceiver 502) in conjunction with communication component 198 / configuration component 240.

[0084] At 702, method 700 includes measuring, by the UE, one or more synchronization signal block (SSB) beams from a network entity. In an aspect, the UE 104 and / or the communication component 198 / configuration component 240 can be configured to measure the one or more SSB beams from the network entity. Thus, the UE 104 and / or the communication component 198 / configuration component 240 (e.g., in conjunction with the controller / processor 359 (which may include memory 360), the processor(s) 512 (which may include memory 516), the modem 540, the TX processor 368, and the transceiver 502) can define means for measuring, by the UE, one or more synchronization signal block (SSB) beams from the network entity.

[0085] In an example of method 700, the UE 104 and / or the communication component 198 / configuration component 240 configured to measure one or more SSB beams further includes measuring a corresponding RSRP for each of the one or more SSB beams.

[0086] In an example of method 700, UE 104 and / or communication component 198 / configuration component 240 configured to measure one or more SSB beams also includes measuring one or more neighbor SSB transmit beams paired with the one or more receive beams at the current location of the UE. For example, the one or more neighbor SSB transmit beams correspond to VSSSB beams.

[0087] At 704, method 700 includes selecting, by the UE, a highest-ranking SSB beam from the one or more SSB beams based on one or more selection factors. In an aspect, the UE 104 and / or the communication component 198 / configuration component 240 can be configured to select the highest-ranking SSB beam from the one or more SSB beams based on the one or more selection factors. Thus, the UE 104 and / or the communication component 198 / configuration component 240 (e.g., in conjunction with the controller / processor 359 (which may include memory 360), the processor(s) 512 (which may include memory 516), the modem 540, the RX processor 356, and the transceiver 502) can define means for selecting, by the UE, the highest-ranking SSB beam from the one or more SSB beams based on the one or more selection factors.

[0088] In an example of method 700, the one or more selection factors include a PBCH CRC threshold.

[0089] In an example of method 700, the UE 104 and / or communication component 198 / configuration component 240 configured to select the highest ranked SSB beam further includes selecting the highest ranked SSB beam from one or more SSB beams using a corresponding PBCH CRC that satisfies a PBCH CRC threshold.

[0090] In an example of method 700, the UE 104 and / or communication component 198 / configuration component 240 configured to select a highest-ranking SSB beam from one or more SSB beams also includes ranking corresponding RSRPs for each of the one or more SSB beams, wherein the RSRP of an SSB beam having the highest average power among the one or more SSB beams corresponds to the highest-ranking SSB beam.

[0091] At 706, method 700 includes starting, by the UE, a timer in response to selecting the highest-rated SSB beam. In an aspect, UE 104 and / or communication component 198 / configuration component 240 can be configured to start a timer in response to selecting the highest-rated SSB beam. Thus, UE 104 and / or communication component 198 / configuration component 240 (e.g., in conjunction with controller / processor 359 (which may include memory 360), processor(s) 512 (which may include memory 516), modem 540, RX processor 356, and transceiver 502) can define means for starting, by the UE, a timer in response to selecting the highest-rated SSB beam.

[0092] At 708, method 700 includes determining, by the UE, whether a medium access control (MAC) control element (CE) is received from the network entity before the expiration of the timer. In an aspect, the UE 104 and / or the communication component 198 / configuration component 240 can be configured to determine whether a MAC CE is received from the network entity before the expiration of the timer. Thus, the UE 104 and / or the communication component 198 / configuration component 240 (e.g., in conjunction with the controller / processor 359 (which may include memory 360), the processor(s) 512 (which may include memory 516), the modem 540, the RX processor 356, and the transceiver 502) can define means for determining, by the UE, whether a MAC CE is received from the network entity before the expiration of the timer.

[0093] At 710, method 700 includes sending, by the UE, a request for an RRC reconfiguration message to a network entity based on determining that a MAC CE was not received from the network entity before expiration of a timer, the RRC reconfiguration message including an identification of the highest-ranking SSB beam. In an aspect, the UE 104 and / or the communication component 198 / configuration component 240 can be configured to send, to the network entity, a request for an RRC reconfiguration message including an identification of the highest-ranking SSB beam based on determining that a MAC CE was not received from the network entity before expiration of the timer. Thus, the UE 104 and / or the communication component 198 / configuration component 240 (e.g., in conjunction with the controller / processor 359 (which may include memory 360), the processor(s) 512 (which may include memory 516), the modem 540, the RX processor 356, and the transceiver 502) may define means for sending, by the UE, a request for an RRC reconfiguration message to a network entity based on a determination that a MAC CE was not received from the network entity before expiration of a timer, the RRC reconfiguration message including an identification of the highest-rated SSB beam.

[0094] In an example of method 700, the request corresponds to a measurement report message having an additional field containing information associated with the request.

[0095] In an example of method 700, the request is associated with a handshake procedure between the UE and a network entity.

[0096] At 712, method 700 includes receiving, by the UE, an RRC reconfiguration message from the network entity in response to sending the request. In one aspect, the UE 104 and / or the communication component 198 / configuration component 240 can be configured to receive the RRC reconfiguration message from the network entity in response to sending the request. Thus, the UE 104 and / or the communication component 198 / configuration component 240 (e.g., in conjunction with the controller / processor 359 (which may include memory 360), the processor(s) 512 (which may include memory 516), the modem 540, the RX processor 356, and the transceiver 502) can define means for receiving, by the UE, an RRC reconfiguration message from the network entity in response to sending the request.

[0097] At 714, method 700 includes performing, by the UE, a beam switch from a current SSB beam to a highest-rated SSB beam based on the RRC reconfiguration message. In an aspect, the UE 104 and / or the communication component 198 / configuration component 240 may be configured to perform the beam switch from the current SSB beam to the highest-rated SSB beam based on the RRC reconfiguration message. Thus, the UE 104 and / or the communication component 198 / configuration component 240 (e.g., in conjunction with the controller / processor 359 (which may include memory 360), the processor(s) 512 (which may include memory 516), the modem 540, the RX processor 356, and the transceiver 502) may define means for performing, by the UE, a beam switch from a current SSB beam to a highest-rated SSB beam based on the RRC reconfiguration message.

[0098] refer to Figure 8 , one example of an implementation of the UE 104 may include various components, some of which have been described above and further described herein, including components such as one or more processors 812 and memory 816 in communication via one or more buses 844 and a transceiver 802, which may operate in conjunction with a modem 840 and / or communication component 198 for improved handling of RLF.

[0099] In one aspect, the one or more processors 812 may include the modem 840 and / or may be part of the modem 840 using one or more modem processors. Thus, various functions associated with the communication component 198 may be included in the modem 840 and / or the processor 812 and, in one aspect, may be performed by a single processor, while in other aspects, different ones of these functions may be performed by a combination of two or more different processors. For example, in one aspect, the one or more processors 812 may include any one or any combination of a modem processor, a baseband processor, a digital signal processor, a transmit processor, a receiver processor, or a transceiver processor associated with the transceiver 802. In other aspects, some features of the one or more processors 812 and / or the modem 840 associated with the communication component 198 may be performed by the transceiver 802.

[0100] In addition, the memory 816 can be configured to store data used herein and / or local versions of one or more of the applications 875 or the communication component 198 and / or subcomponents executed by the at least one processor 812. The memory 816 can include any type of computer-readable medium usable by a computer or the at least one processor 812, such as random access memory (RAM), read-only memory (ROM), tape, magnetic disk, optical disk, volatile memory, non-volatile memory, and any combination thereof. In one aspect, for example, the memory 816 can be a non-transitory computer-readable storage medium that stores one or more computer-executable codes and / or data associated therewith that define one or more of the communication component 198 and / or its subcomponents when the UE 104 is operating the at least one processor 812 to execute one or more of the communication component 198 and / or its subcomponents.

[0101] The transceiver 802 may include at least one receiver 806 and at least one transmitter 808. The receiver 806 may include hardware and / or software executable by a processor for receiving data, the code including instructions stored in a memory (e.g., a computer-readable medium). The receiver 806 may be, for example, a radio frequency (RF) receiver. In one aspect, the receiver 806 may receive signals transmitted by at least one base station 102. In addition, the receiver 806 may process these received signals and may also obtain measurements of these signals, such as, but not limited to, Ec / Io, signal-to-noise ratio (SNR), reference signal received power (RSRP), received signal strength indicator (RSSI), etc. The transmitter 808 may include hardware and / or software executable by a processor for transmitting data, the code including instructions stored in a memory (e.g., a computer-readable medium). Suitable examples of the transmitter 808 may include, but are not limited to, an RF transmitter.

[0102] Furthermore, in an aspect, the UE 104 may include an RF front end 888 that may operate in communication with the one or more antennas 865 and the transceiver 802 for receiving and transmitting radio transmissions, such as wireless communications transmitted by at least one base station 102 or wireless transmissions transmitted by the UE 104. The RF front end 888 may be connected to the one or more antennas 865 and may include one or more low noise amplifiers (LNAs) 890, one or more switches 892, one or more power amplifiers (PAs) 898, and one or more filters 896 for transmitting and receiving RF signals.

[0103] In one aspect, the LNAs 890 can amplify received signals at a desired output level. In one aspect, each LNA 890 can have specified minimum and maximum gain values. In one aspect, the RF front end 888 can use one or more switches 892 to select a particular LNA 890 and its specified gain value based on the desired gain value for a particular application.

[0104] Furthermore, for example, the RF front end 888 can use one or more PAs 898 to amplify the signal for RF output at a desired output power level. In one aspect, each PA 898 can have a specified minimum and maximum gain value. In one aspect, the RF front end 888 can use one or more switches 892 to select a particular PA 898 and its specified gain value based on the desired gain value for a particular application.

[0105] Furthermore, for example, the RF front end 888 can use one or more filters 896 to filter received signals to obtain input RF signals. Similarly, in one aspect, for example, a corresponding filter 896 can be used to filter the output from a corresponding PA 898 to produce an output signal for transmission. In one aspect, each filter 896 can be connected to a specific LNA 890 and / or PA 898. In one aspect, the RF front end 888 can use one or more switches 892 to select a transmit or receive path using a specific filter 896, LNA 890, and / or PA 898 based on a configuration as specified by the transceiver 802 and / or processor 812.

[0106] Thus, the transceiver 802 can be configured to transmit and receive wireless signals via the RF front end 888 through one or more antennas 865. In an aspect, the transceiver can be tuned to operate at a specified frequency so that the UE 104 can communicate with, for example, one or more base stations 102 or one or more cells associated with one or more base stations 102. In an aspect, the modem 840 can configure the transceiver 802 to operate at a specified frequency and power level based on, for example, the UE configuration of the UE 104 and the communication protocol used by the modem 840.

[0107] In one aspect, the modem 840 can be a multi-band-multimode modem that can process digital data and communicate with the transceiver 802 so that the digital data is sent and received using the transceiver 802. In one aspect, the modem 840 can be multi-band and configured to support multiple frequency bands for a specific communication protocol. In one aspect, the modem 840 can be multi-mode and configured to support multiple operating networks and communication protocols. In one aspect, the modem 840 can control one or more components of the UE 104 (e.g., the RF front end 888, the transceiver 802) to enable transmission and / or reception of signals from the network based on a specified modem configuration. In one aspect, the modem configuration can be based on the mode of the modem and the frequency band in use. In another aspect, the modem configuration can be based on UE configuration information associated with the UE 104, such as provided by the network during cell selection and / or cell reselection.

[0108] In one aspect, processor(s) 812 may correspond to a processor in conjunction with Figure 3 Similarly, the memory 816 may correspond to one or more of the processors described in the UE. Figure 3 The memory described by the UE in .

[0109] refer to Figure 9 , one example of an implementation of a base station 102 (e.g., base station 102 as described above) may include various components, some of which have been described above, but including components such as one or more processors 912 and memory 916 that communicate via one or more buses 944 and a transceiver 902 that may operate in conjunction with a modem 940 and communication component 199 for transmitting reference signals.

[0110] The transceiver 902, receiver 906, transmitter 908, one or more processors 912, memory 916, applications 975, bus 944, RF front end 988, LNA 990, switch 992, filter 996, PA 998 and one or more antennas 965 can be the same as or similar to the corresponding components of the UE 104 described above, but are configured or otherwise programmed for base station operation rather than UE operation.

[0111] In one aspect, processor(s) 912 may correspond to a processor in conjunction with Figure 3 Similarly, the memory 916 may correspond to one or more of the processors described in the base station of FIG. Figure 3 The memory of the base station description in.

[0112] Some additional example clauses

[0113] Examples of implementations are described in the following numbered clauses:

[0114] 1. A method of wireless communication at a user equipment (UE), comprising:

[0115] measuring one or more synchronization signal block (SSB) beams from a network entity;

[0116] selecting a highest-ranking SSB beam from the one or more SSB beams based on one or more selection factors;

[0117] sending a beam report including the identification of the highest-rated SSB beam to the network entity;

[0118] starting a timer in response to transmitting the beam report;

[0119] determining whether a medium access control (MAC) control element (CE) is received from a network entity before expiration of a timer; and

[0120] Beam switching from the current SSB beam to the highest-ranking SSB beam is performed based on determining that no MAC CE is received from the network entity before the timer expires.

[0121] 2. The method of claim 1 , wherein the one or more selection factors comprise a physical broadcast channel (PBCH) cyclic redundancy check (CRC) threshold.

[0122] 3. The method of claim 2, wherein selecting the highest-ranking SSB beam further comprises selecting the highest-ranking SSB beam from one or more SSB beams using a corresponding PBCH CRC that satisfies a PBCH CRC threshold.

[0123] 4. The method of claim 1 , wherein performing beam switching from the current SSB beam to the highest-ranking SSB beam is further based on determining that a beam failure detection or beam failure recovery procedure has not been initiated before expiration of a second timer.

[0124] 5. The method of claim 1 , wherein determining whether a MAC CE is received from the network entity before the timer expires further comprises determining whether a MAC CE is received from the network entity on a physical downlink shared channel (PDSCH) or a physical downlink control channel (PDCCH) before the timer expires.

[0125] 6. The method of claim 1 , wherein measuring the one or more SSB beams further comprises measuring a corresponding reference signal received power (RSRP) for each of the one or more SSB beams.

[0126] 7. The method of claim 1 , wherein selecting the highest-ranked SSB beam from the one or more SSB beams further comprises ranking corresponding RSRPs for each of the one or more SSB beams, wherein the RSRP of an SSB beam having the highest average power among the one or more SSB beams corresponds to the highest-ranked SSB beam.

[0127] 8. The method of claim 1 , wherein measuring one or more SSB beams further comprises measuring one or more neighbor SSB transmit beams paired with one or more receive beams at a current location of the UE.

[0128] 9. The method of claim 8, wherein the one or more neighbor SSB transmit beams correspond to a virtual service SSB (VSSSB) beam.

[0129] 10. A wireless communication method at a user equipment (UE), comprising:

[0130] measuring one or more synchronization signal block (SSB) beams from a network entity;

[0131] selecting a highest-ranking SSB beam from the one or more SSB beams based on one or more selection factors;

[0132] starting a timer in response to selecting the highest rated SSB beam;

[0133] determining whether a medium access control (MAC) control element (CE) is received from a network entity before expiration of a timer;

[0134] Based on determining that a MAC CE is not received from the network entity before expiration of the timer, sending a request for a radio resource control (RRC) reconfiguration message to the network entity, the RRC reconfiguration message including an identification of a highest-rated SSB beam;

[0135] receiving an RRC reconfiguration message from the network entity in response to the sending request; and

[0136] Beam switching from the current SSB beam to the highest-ranking SSB beam is performed based on the RRC reconfiguration message.

[0137] 11. The method of claim 10, wherein the one or more selection factors include a physical broadcast channel (PBCH) cyclic redundancy check (CRC) threshold.

[0138] 12. The method of claim 11, wherein selecting the highest-ranking SSB beam further comprises selecting the highest-ranking SSB beam from one or more SSB beams using a corresponding PBCH CRC that satisfies a PBCH CRC threshold.

[0139] 13. The method of claim 10, wherein the request corresponds to a measurement report message having an additional field including information associated with the request.

[0140] 14. The method of claim 10, wherein the request is associated with a handshake procedure between the UE and a network entity.

[0141] 15. The method of claim 10, wherein measuring the one or more SSB beams further comprises measuring a corresponding reference signal received power (RSRP) for each of the one or more SSB beams.

[0142] 16. The method of claim 10, wherein selecting the highest-ranked SSB beam from the one or more SSB beams further comprises ranking corresponding RSRPs for each of the one or more SSB beams, wherein the RSRP of an SSB beam having the highest average power among the one or more SSB beams corresponds to the highest-ranked SSB beam.

[0143] 17. The method of claim 10, wherein measuring one or more SSB beams further comprises measuring one or more neighbor SSB transmit beams paired with one or more receive beams at a current location of the UE.

[0144] 18. The method of claim 17, wherein the one or more neighbor SSB transmit beams correspond to a virtual service SSB (VSSSB) beam.

[0145] 19. An apparatus for wireless communication at a user equipment (UE), comprising:

[0146] transceiver;

[0147] a memory configured to store instructions; and

[0148] One or more processors communicatively coupled to the transceiver and the memory, wherein the one or more processors are configured to execute instructions to:

[0149] measuring one or more synchronization signal block (SSB) beams from a network entity;

[0150] selecting a highest-ranking SSB beam from the one or more SSB beams based on one or more selection factors;

[0151] sending a beam report including the identification of the highest-rated SSB beam to the network entity;

[0152] starting a timer in response to transmitting the beam report;

[0153] determining whether a medium access control (MAC) control element (CE) is received from a network entity before expiration of a timer; and

[0154] Beam switching from the current SSB beam to the highest-ranking SSB beam is performed based on determining that no MAC CE is received from the network entity before the timer expires.

[0155] 20. The apparatus of claim 19, wherein the one or more selection factors include a physical broadcast channel (PBCH) cyclic redundancy check (CRC) threshold.

[0156] 21. The apparatus of claim 20, wherein selecting the highest-ranking SSB beam further comprises selecting the highest-ranking SSB beam from the one or more SSB beams using a corresponding PBCH CRC that satisfies a PBCH CRC threshold.

[0157] 22. The apparatus of claim 19, wherein performing a beam switch from a current SSB beam to a highest-ranking SSB beam is further based on determining that a beam failure detection or beam failure recovery procedure has not been initiated before expiration of a second timer.

[0158] 23. The apparatus of claim 19, wherein determining whether a MAC CE is received from the network entity before expiration of the timer further comprises determining whether a MAC CE is received from the network entity on a physical downlink shared channel (PDSCH) or a physical downlink control channel (PDCCH) before expiration of the timer.

[0159] 24. The apparatus of claim 19, wherein measuring the one or more SSB beams further comprises measuring a corresponding reference signal received power (RSRP) for each of the one or more SSB beams.

[0160] 25. An apparatus for wireless communication at a user equipment (UE), comprising:

[0161] transceiver;

[0162] a memory configured to store instructions; and

[0163] One or more processors communicatively coupled to the transceiver and the memory, wherein the one or more processors are configured to execute instructions to:

[0164] measuring one or more synchronization signal block (SSB) beams from a network entity;

[0165] selecting a highest-ranking SSB beam from the one or more SSB beams based on one or more selection factors;

[0166] starting a timer in response to selecting the highest rated SSB beam;

[0167] determining whether a medium access control (MAC) control element (CE) is received from a network entity before expiration of a timer;

[0168] Based on determining that a MAC CE is not received from the network entity before expiration of the timer, sending a request for a radio resource control (RRC) reconfiguration message to the network entity, the RRC reconfiguration message including an identification of a highest-rated SSB beam;

[0169] receiving an RRC reconfiguration message from the network entity in response to the sending request; and

[0170] Beam switching from the current SSB beam to the highest-ranking SSB beam is performed based on the RRC reconfiguration message.

[0171] 26. The apparatus of claim 25, wherein the one or more selection factors include a physical broadcast channel (PBCH) cyclic redundancy check (CRC) threshold.

[0172] 27. The apparatus of claim 26, wherein selecting the highest-ranking SSB beam further comprises selecting the highest-ranking SSB beam from the one or more SSB beams using a corresponding PBCH CRC that satisfies a PBCH CRC threshold.

[0173] 28. The apparatus of claim 25, wherein the request corresponds to a measurement report message having an additional field comprising information associated with the request.

[0174] 29. The apparatus of claim 25, wherein the request is associated with a handshake procedure between the UE and a network entity.

[0175] 30. The apparatus of claim 25, wherein measuring the one or more SSB beams further comprises measuring a corresponding reference signal received power (RSRP) for each of the one or more SSB beams.

[0176] It should be understood that the specific order or hierarchy of the blocks in the disclosed process / flowcharts is illustrative of example implementations. Based on design preferences, it should be understood that the specific order or hierarchy of the blocks in the process / flowcharts may be rearranged. In addition, some blocks may be combined or omitted. The accompanying method claims present the elements of the blocks in a sample order and are not meant to be limited to the specific order or hierarchy presented.

[0177] The preceding description is provided to enable any person skilled in the art to practice the various aspects described herein. It will be apparent to those skilled in the art that various modifications to these aspects will be apparent, and the general principles defined herein can be applied to other aspects. Therefore, the present claims are not intended to be limited to the various aspects shown herein, but rather to the full scope consistent with the language claims, wherein, unless otherwise specified, reference to an element in the singular is not intended to represent "one and only one", but rather to represent "one or more". The word "exemplary" is used herein to represent "serving as an example, instance, or illustration". Any aspect described herein as "exemplary" is not necessarily to be interpreted as being superior to or advantageous to other aspects. Unless otherwise expressly stated, the term "some" refers to one or more. Terms such as "at least one of A, B, or C", "one or more of A, B, or C", "at least one of A, B, and C", "one or more of A, B, and C", and "A, B, C, or any combination thereof" include any combination of A, B, and / or C, and may include multiple A, multiple B, or multiple C. Specifically, phrases such as “at least one of A, B, or C,” “one or more of A, B, or C,” “at least one of A, B, and C,” “one or more of A, B, and C,” and “A, B, C, or any combination thereof” may be A only, B only, C only, A and B, A and C, B and C, or A and B and C, wherein any such combination may include one or more members of A, B, or C. All structural and functional equivalents of the elements throughout the various aspects described in this disclosure that are known or hereafter known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Furthermore, nothing disclosed herein is intended to be dedicated to the public, regardless of whether such disclosure is expressly recited in the claims. The words “module,” “mechanism,” “element,” “device,” etc. may not replace the word “component.” Therefore, no claim element should be interpreted as a part-plus-function unless the phrase “component for…” is used to expressly recite the claim element.

Claims

1. A method for wireless communication at a user equipment (UE), comprising: measuring one or more synchronization signal block (SSB) beams from a network entity; selecting a highest-ranking SSB beam from the one or more SSB beams based on one or more selection factors; sending a beam report including an identification of the highest-rated SSB beam to the network entity; starting a timer in response to sending the beam report; determining whether a Medium Access Control (MAC) Control Element (CE) is received from the network entity before the timer expires; and Performing a beam switch from a current SSB beam to a highest-ranking SSB beam based on determining that the MAC CE is not received from the network entity before the timer expires.

2. The method according to claim 1, wherein The one or more selection factors include a physical broadcast channel (PBCH) cyclic redundancy check (CRC) threshold.

3. The method according to claim 2, wherein: Selecting the highest-ranking SSB beam further includes selecting the highest-ranking SSB beam from the one or more SSB beams using a corresponding PBCH CRC that satisfies the PBCH CRC threshold.

4. The method according to claim 1, wherein Performing the beam switching from the current SSB beam to the highest-ranking SSB beam is further based on determining that a beam failure detection or beam failure recovery procedure has not been initiated before expiration of a second timer.

5. The method according to claim 1, wherein Determining whether the MAC CE is received from the network entity before the timer expires further includes determining whether the MAC CE is received from the network entity on a physical downlink shared channel (PDSCH) or a physical downlink control channel (PDCCH) before the timer expires.

6. The method of claim 1, wherein: Measuring the one or more SSB beams further includes measuring a corresponding reference signal received power RSRP for each of the one or more SSB beams.

7. The method of claim 1, wherein: Selecting the highest-ranked SSB beam from the one or more SSB beams further comprises ranking corresponding RSRPs for each of the one or more SSB beams, wherein the RSRP of one of the one or more SSB beams having the highest average power corresponds to the highest-ranked SSB beam.

8. The method of claim 1, wherein: Measuring the one or more SSB beams also includes measuring one or more neighbor SSB transmit beams paired with one or more receive beams at the current location of the UE.

9. The method of claim 8, wherein: The one or more neighbor SSB transmit beams correspond to virtual service SSB VSSSB beams.

10. A method of wireless communication at a user equipment (UE), comprising: measuring one or more synchronization signal block (SSB) beams from a network entity; selecting a highest-ranking SSB beam from the one or more SSB beams based on one or more selection factors; starting a timer in response to selecting the highest-rated SSB beam; determining whether a medium access control (MAC) control element (CE) is received from the network entity before the timer expires; Based on determining that the MAC CE is not received from the network entity before the timer expires, sending a request for a radio resource control (RRC) reconfiguration message to the network entity, the RRC reconfiguration message including an identification of the highest-ranking SSB beam; receiving the RRC reconfiguration message from the network entity in response to sending the request; as well as Beam switching is performed from a current SSB beam to the highest-ranking SSB beam based on the RRC reconfiguration message.

11. The method according to claim 10, wherein: The one or more selection factors include a physical broadcast channel (PBCH) cyclic redundancy check (CRC) threshold.

12. The method of claim 11, wherein: Selecting the highest-ranking SSB beam further includes selecting the highest-ranking SSB beam from the one or more SSB beams using a corresponding PBCH CRC that satisfies the PBCH CRC threshold.

13. The method of claim 10, wherein: The request corresponds to a measurement report message having an additional field including information associated with the request.

14. The method of claim 10, wherein: The request is associated with a handshake procedure between the UE and the network entity.

15. The method of claim 10, wherein: Measuring the one or more SSB beams further includes measuring a corresponding reference signal received power RSRP for each of the one or more SSB beams.

16. The method of claim 10, wherein: Selecting the highest-ranked SSB beam from the one or more SSB beams further comprises ranking corresponding RSRPs for each of the one or more SSB beams, wherein the RSRP of one of the one or more SSB beams having the highest average power corresponds to the highest-ranked SSB beam.

17. The method of claim 10, wherein: Measuring the one or more SSB beams also includes measuring one or more neighbor SSB transmit beams paired with one or more receive beams at the current location of the UE.

18. The method of claim 17, wherein: The one or more neighbor SSB transmit beams correspond to virtual service SSB VSSSB beams.

19. An apparatus for performing wireless communication at a user equipment (UE), comprising: transceiver; a memory configured to store instructions; as well as one or more processors communicatively coupled to the transceiver and the memory, wherein the one or more processors are configured to execute the instructions to: measuring one or more synchronization signal block (SSB) beams from a network entity; selecting a highest-ranking SSB beam from the one or more SSB beams based on one or more selection factors; sending a beam report including an identification of the highest-rated SSB beam to the network entity; starting a timer in response to sending the beam report; determining whether a Medium Access Control (MAC) Control Element (CE) is received from the network entity before the timer expires; and Performing a beam switch from a current SSB beam to a highest-ranking SSB beam based on determining that the MAC CE is not received from the network entity before the timer expires.

20. The apparatus of claim 19, wherein The one or more selection factors include a physical broadcast channel (PBCH) cyclic redundancy check (CRC) threshold.

21. The apparatus of claim 20, wherein: Selecting the highest-ranking SSB beam further includes selecting the highest-ranking SSB beam from the one or more SSB beams using a corresponding PBCH CRC that satisfies the PBCH CRC threshold.

22. The apparatus of claim 19, wherein: Performing the beam switching from the current SSB beam to the highest-ranking SSB beam is further based on determining that a beam failure detection or beam failure recovery procedure has not been initiated before expiration of a second timer.

23. The apparatus of claim 19, wherein: Determining whether the MAC CE is received from the network entity before the timer expires further includes determining whether the MAC CE is received from the network entity on a physical downlink shared channel (PDSCH) or a physical downlink control channel (PDCCH) before the timer expires.

24. The apparatus of claim 19, wherein: Measuring the one or more SSB beams further includes measuring a corresponding reference signal received power RSRP for each of the one or more SSB beams.

25. An apparatus for performing wireless communication at a user equipment (UE), comprising: transceiver; a memory configured to store instructions; as well as one or more processors communicatively coupled to the transceiver and the memory, wherein the one or more processors are configured to execute the instructions to: measuring one or more synchronization signal block (SSB) beams from a network entity; selecting a highest-ranking SSB beam from the one or more SSB beams based on one or more selection factors; starting a timer in response to selecting the highest-rated SSB beam; determining whether a medium access control (MAC) control element (CE) is received from the network entity before the timer expires; Based on determining that the MAC CE is not received from the network entity before the timer expires, sending a request for a radio resource control (RRC) reconfiguration message to the network entity, the RRC reconfiguration message including an identification of the highest-ranking SSB beam; receiving the RRC reconfiguration message from the network entity in response to sending the request; and Beam switching is performed from a current SSB beam to the highest-ranking SSB beam based on the RRC reconfiguration message.

26. The apparatus of claim 25, wherein: The one or more selection factors include a physical broadcast channel (PBCH) cyclic redundancy check (CRC) threshold.

27. The apparatus of claim 26, wherein: Selecting the highest-ranking SSB beam further includes selecting the highest-ranking SSB beam from the one or more SSB beams using a corresponding PBCH CRC that satisfies the PBCH CRC threshold.

28. The apparatus of claim 25, wherein: The request corresponds to a measurement report message having an additional field including information associated with the request.

29. The apparatus of claim 25, wherein: The request is associated with a handshake procedure between the UE and the network entity.

30. The apparatus of claim 25, wherein: Measuring the one or more SSB beams further includes measuring a corresponding reference signal received power RSRP for each of the one or more SSB beams.

31. A computer-readable storage medium having stored thereon instructions that, when executed, cause one or more processors to perform the method of any one of claims 1-18.

32. A computer program product comprising computer readable instructions which, when executed by a processor, cause the processor to perform the method according to any one of claims 1 to 18.

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