Media access control procedure indicated by beam index

Abstract

Methods, systems, and devices for wireless communication are described. A user equipment (UE) may select a beam from a set of beams and send an indication of the selected beam in a media access control (MAC) control element to establish a communication link with a base station. In some cases, the user equipment may select the beam and indicate the selection based on identifying a beam failure and / or determining to perform a random access procedure. When transmitting the indication of a selected beam, the user equipment may obtain uplink resources for the transmission based on the availability of the uplink resources. For example, if the uplink resource is available, the user equipment may transmit the indication of a selected beam multiplexed with an uplink transmission. Alternatively, if the uplink resource is not available, the user equipment may request the indicated uplink resource for transmitting the selected beam.

Description

[0001] This patent application is a divisional application of the following invention patent application:

[0002] Application Number: 202080057294.5

[0003] Application date: August 14, 2020

[0004] Invention Title: Media Access Control Process Based on Beam Index Indication

[0005] Cross-referencing

[0006] This patent application claims the benefit of U.S. Provisional Patent Application No. 62 / 887,631, filed August 15, 2019, entitled “Media Access Control Procedures for Beam Index Indications”; PCT International Application No. PCT / CN2019 / 102367, filed August 23, 2019, entitled “Scheduling Request for Cell-Specific Resources”; and U.S. Patent Application No. 16 / 993,023, filed August 13, 2020, entitled “Media Access Control Procedures for Beam Index Indications”; each of which is assigned to the assignee of this invention. Background Technology

[0007] Wireless communication systems are widely deployed to provide various types of communication content, such as voice, video, packet data, messaging, and broadcasting. These systems are able to support communication with multiple users by sharing available system resources, such as time, frequency, and power. Examples of such multiple access systems include fourth-generation (4G) systems, such as Long Term Evolution (LTE), LTE-Advanced (LTE-A), or LTE-A Pro (LTE-A), and fifth-generation (5G) systems, which may be referred to as New Radio (NR). These systems can employ technologies such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), or Discrete Fourier Transform Extended Orthogonal Frequency Division Multiplexing (DFT-S-OFDM).

[0008] Wireless multiple access communication systems can include multiple base stations or network access nodes, each supporting communication from multiple communication devices simultaneously, which may also be referred to as user equipment (UEs). In some cases, UEs and base stations can communicate via beamforming techniques, where each wireless device uses a directional beam to send signals to or receive signals from other wireless devices. For example, both the UE and the base station can use a set of antennas to send or receive signals in a specific direction, rather than sending signals in many directions (e.g., omnidirectional), making the signal stronger in that specific direction. However, the UE and base station can form multiple beams simultaneously to increase the chances of successful signal transmission and reception. Therefore, there is a need for techniques to indicate the preferred beam (e.g., a stronger beam) for subsequent communication. Summary of the Invention

[0009] The described technology relates to improved methods, systems, devices, and apparatuses to support Media Access Control (MAC) procedures for beam index indication. Typically, the described technology provides a User Equipment (UE) with the ability to select a first beam (e.g., a preferred beam) from a set of beams and, in the MAC control element (CE), transmit an indication of the selected first beam to a base station to establish a communication link with that base station. In some cases, the UE can select the first beam and, based on identifying beam failures on at least one cell communicating with the base station, determine whether to establish the communication link via a Random Access Channel (RACH) procedure (e.g., two-step RACH, four-step RACH, etc.), or a combination thereof. When transmitting the indication of the selected beam, the UE can base its decision on a comparison of uplink resource availability with a threshold (e.g., whether the uplink resource is available in the future). The user equipment (UE) obtains the uplink resource to transmit within a time slot (which is scheduled within that time slot). For example, if the uplink resource is available, the UE can transmit an indication of the selected first beam multiplexed with the MAC CE. Alternatively, if the uplink resource is unavailable, the UE can request the uplink resource (e.g., via a configured uplink resource, via a scheduling request, etc.) to transmit the indication of the selected first beam.

[0010] A method for wireless communication at a user equipment is described. The method may include: determining a communication link to be established between the user equipment and a serving cell of a base station; the user equipment selecting a first beam from a set of candidate beams of the serving cell to establish the communication link; and, based on a timing and threshold comparison of uplink resource availability, transmitting an indication of the selected first beam to the base station in a MAC CE on the uplink resource.

[0011] An apparatus for wireless communication at a user equipment is described. The apparatus may include a processor, a memory coupled to the processor, and instructions stored in the memory. The instructions are executable by the processor to cause the apparatus to determine a communication link to be established between the user equipment and a serving cell of a base station; to have the user equipment select a first beam from a set of candidate beams of the serving cell to establish the communication link; and to transmit an indication of the selected first beam to the base station on the uplink resources in a MAC CE based on a timing and threshold comparison of uplink resource availability.

[0012] Another apparatus for wireless communication at a user equipment is described. The apparatus may include components for determining a communication link to be established between the user equipment and a serving cell of a base station; selecting a first beam from a set of candidate beams of the serving cell by the user equipment to establish the communication link; and, based on a timing and threshold comparison of uplink resource availability, transmitting an indication of the selected first beam to the base station in a MAC CE on the uplink resource.

[0013] A non-transitory computer-readable medium is described, storing code for wireless communication at a user equipment. The code may include processor-executable instructions to determine a communication link to be established between the user equipment and a serving cell of a base station; for the user equipment to select a first beam from a set of candidate beams of the serving cell to establish the communication link; and for a timing comparison with a threshold based on the availability of uplink resources, transmitting an indication of the selected first beam to the base station in a MAC CE on those uplink resources.

[0014] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, components, or instructions for initiating a request for uplink resources to transmit an indication of a selected first beam to the base station. Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may further include operations, features, components, or instructions for transmitting the request on uplink control resources, the request indicating to the base station a faulty beam of the serving cell; and, in response to the transmitted request, receiving from the base station an indication of uplink resources in a second serving cell for the user equipment to use to transmit the indication of the selected first beam.

[0015] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, the request may include operations, features, components, or instructions for transmitting the request on dedicated uplink control resources, the request being configured to indicate to the base station a possibly faulty beam or set of beams configured for the first serving cell; and in response to the transmitted request, receiving downlink information from a second serving cell of the base station, the downlink information indicating uplink resources of the second serving cell for the user equipment to use to transmit the selected first beam.

[0016] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, components, or instructions for transmitting a request on uplink control resources at a transmission occasion, the uplink control resources indicating to the base station a possibly faulty beam of the serving cell, and the transmission occasion of the uplink control resources associated with the set of serving cells indicating a possibly faulty beam of the serving cell; and in response to the transmitted request, receiving from the base station an indication of uplink resources in a second serving cell different from the serving cell, for the user equipment to use to transmit an indication of a selected first beam.

[0017] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the request includes a random access message of a random access procedure to establish a communication link between the user equipment and the serving cell of the base station.

[0018] In some examples of the methods, apparatuses and non-transitory computer-readable media described herein, determining the establishment of the communication link may include operations, features, components or instructions for communicating with the base station via the communication link, identifying beam faults in the communication link between the user equipment and the serving cell, and determining the establishment of the communication link between the user equipment and the serving cell based on the identified beam faults.

[0019] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, the indication to transmit a selected first beam in the MAC CE based on the comparison may include operations, features, components, or indications for obtaining the uplink resources available for use by the user equipment to transmit the indication of the first beam; comparing a time slot threshold number with the number of time slots between the current time and the uplink resources, wherein the threshold includes the time slot threshold number; determining the availability of the uplink resources based on the fact that the number of time slots between the current time and the uplink resources is less than the time slot threshold number; and transmitting the indication of the selected first beam in the MAC CE based on the determined availability indicating that the number of time slots between the current time and the uplink resources is less than the time slot threshold number.

[0020] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, transmitting an indication of a selected first beam in the MAC CE based on the comparison may include operations, features, components, or indications for obtaining the uplink resource for the user equipment to use to transmit the indication of the first beam; comparing a time slot threshold number with a time slot number between the current time and the uplink resource, wherein the threshold includes the time slot threshold number; determining the availability of the uplink resource based on the fact that the time slot number between the current time and the uplink resource is less than the time slot threshold number; sending a request for the uplink resource to the base station based on the determined availability indicating that the time slot number between the current time and the uplink resource is greater than the time slot threshold number; receiving an indication of the uplink resource in response to the sent request; and transmitting an indication of the selected first beam in the MAC CE on the indicated uplink resource.

[0021] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may further include operations, features, components, or instructions for receiving a beam fault recovery configuration and a request for the uplink resource sent based on the received configuration.

[0022] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, sending a request for the uplink resource to the base station may include operations, features, components, or instructions for sending a sequence of scheduling requests indicative of the request to the base station.

[0023] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, the sequence of scheduling requests may be transmitted on the uplink resource corresponding to the highest priority logical channel configured for the user equipment.

[0024] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, an indication to transmit a selected first beam may include an operation, feature, component, or instruction for transmitting the MAC CE to the base station in a RACH message of the RACH procedure.

[0025] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, components, or instructions for determining an indication that a second beam among a plurality of candidate beams is available to transmit the first beam at least a threshold earlier than the availability of the uplink resource, wherein the uplink resource includes the first beam, and for transmitting an indication of the selected first beam in a MAC on the second beam based on the determination that the second beam is available.

[0026] In some examples of the methods, apparatuses and non-transitory computer-readable media described herein, an indication of the selected first beam is transmitted on the second beam in the first message of a two-step RACH process.

[0027] In some examples of the methods, apparatuses and non-transitory computer-readable media described herein, an indication of the selected first beam is transmitted on the second beam in the connection request message of the four-step RACH process.

[0028] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may further include operations, features, components, or instructions for performing a logical channel prioritization process for a MAC Protocol Data Unit (PDU) including the MAC CE, wherein the logical channel prioritization process provides the MAC CE with a priority greater than that of each other MAC CE of the MAC PDU, greater than the data of the MAC PDU, and less than the common control channel (CCCH) message of the MAC PDU.

[0029] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may further include operations, features, components, or instructions for starting a timer and a counter based on determining that the communication link is established; incrementing the counter based on an indication to transmit a selected first beam; and retransmitting the indication of the selected first beam in the MAC CE based on the timer expiring before a message is received on the selected first beam and the counter falling below a counter threshold. Attached Figure Description

[0030] Figure 1 An example of a wireless communication system that supports a beam index indication media access control (MAC) procedure according to various aspects of this disclosure is shown.

[0031] Figure 2 An example of a wireless communication system that supports a beam index indication MAC process according to various aspects of this disclosure is shown.

[0032] Figure 3 , Figure 4 and Figure 5 An example of the processing flow of the MAC procedure supporting beam index indication according to various aspects of this disclosure is shown.

[0033] Figure 6 and Figure 7 A block diagram of a device supporting a beam index indication MAC process according to various aspects of this disclosure is shown.

[0034] Figure 8 A block diagram of a communication manager supporting a beam index indication MAC process according to various aspects of this disclosure is shown.

[0035] Figure 9 A diagram of a system including a device supporting a beam index indication MAC process is shown according to various aspects of this disclosure.

[0036] Figures 10 to 12 A flowchart is shown of a method for supporting beam index indication of the MAC process according to various aspects of this disclosure. Detailed Implementation

[0037] To overcome the high path loss associated with high carrier frequencies, base stations and user equipment (UEs) can use beamforming techniques for uplink and downlink communications. In some cases, when determining to establish a communication link with a base station, the UE can identify a preferred beam (e.g., a first beam in a beam set) for establishing that communication link and / or any subsequent communications. For example, this preferred beam can provide the strongest signal quality from the base station from a set of possible beams, which the base station can use to transmit downlink signals to the UE. Subsequently, the UE can send an indication of the preferred beam to the base station on the Media Access Control (MAC) element (CE). Therefore, the base station can then use the preferred beam to transmit subsequent downlink messages to the UE.

[0038] In some cases, the user equipment (UE) may determine to establish a communication link with the base station based on identifying a beam fault that previously occurred in at least one cell (e.g., a secondary cell (SCell)), wherein the preferred beam is used in the beam fault recovery process. Additionally or alternatively, the UE may determine to establish an initial connection with the base station or to re-establish communication with the base station in another cell (e.g., a primary cell (PCell), primary SCell (PSCell), secondary PCell (SPCell), etc.), and the preferred beam may be used in the Random Access Channel (RACH) procedure. When performing the RACH procedure, the UE may send an indication of the preferred beam to the base station in one of the messages of the RACH procedure (e.g., the first message in a two-step RACH procedure, a connection request / third message in a four-step RACH procedure, etc.).

[0039] Additionally, the user equipment can send an indication of the preferred beam to the base station based on a comparison of uplink resource availability with a threshold. For example, if the uplink resource is scheduled and... Available within the time slot (e.g., or (Send Time Intervals (TTIs) of varying lengths), where If the value is a positive integer, then after the user equipment determines to establish the communication link and identifies the preferred beam, the user equipment can multiplex the indication with a MAC Protocol Data Unit (PDU) transmitted on the uplink resource. Alternatively, if the uplink resource is unavailable, the user equipment can request additional uplink resources (e.g., based on configured uplink channel resources, via a scheduling request, etc.) to transmit the indication of the preferred beam.

[0040] Various aspects of this disclosure are initially described in the context of wireless communication systems. Furthermore, these aspects are illustrated by additional examples of wireless communication systems and processing flows. The various aspects of this disclosure are further illustrated and described with reference to apparatus diagrams, system diagrams, and flowcharts relating to the MAC process indicated by beam indexing.

[0041] Figure 1 An example of a wireless communication system 100 supporting a beam index indication MAC process according to various aspects of this disclosure is shown. The wireless communication system 100 includes a base station 105, user equipment 115, and a core network 130. In some examples, the wireless communication system 100 may be a Long Term Evolution (LTE) network, LTE-Advanced (LTE-A), LTE-A Pro network, or a New Radio (NR) network. In some cases, the wireless communication system 100 may support enhanced broadband communication, ultra-reliable (e.g., mission-critical) communication, low-latency communication, or communication with low-cost and low-complexity devices.

[0042] Base station 105 can wirelessly communicate with user equipment 115 via one or more base station antennas. Base station 105 described herein may include, or may be referred to by those skilled in the art as, a base transceiver station, radio base station, access point, radio transceiver, NodeB, eNodeB (eNB), next-generation NodeB or gigabit NodeB (either of which may be referred to as gNB), home NodeB, home eNodeB, or some other suitable terminology. Wireless communication system 100 may include different types of base stations 105 (e.g., macro cell base stations or small cell base stations). The user equipment 115 described herein is capable of communicating with various types of base stations 105 and network infrastructure, including macro NBs, small cell eNBs, gNBs, relay base stations, etc.

[0043] Each base station 105 can be associated with a specific geographic coverage area 110, supporting communication with various user equipment 115. Each base station 105 can provide communication coverage to the corresponding geographic coverage area 110 via a communication link 125, and the communication link 125 between the base station 105 and the user equipment 115 can utilize one or more carriers. The communication link 125 shown in the wireless communication system 100 can include uplink transmission from the user equipment 115 to the base station 105, or downlink transmission from the base station 105 to the user equipment 115. Downlink transmission can also be referred to as forward link transmission, and uplink transmission can also be referred to as reverse link transmission.

[0044] The geographic coverage area 110 of base station 105 can be divided into sectors that constitute part of the geographic coverage area 110, and each sector can be associated with a cell. For example, each base station 105 can provide communication coverage for macro cells, small cells, hotspots, or other types of cells, or various combinations thereof. In some examples, base station 105 can be mobile, thus providing communication coverage for mobile geographic coverage areas 110. In some examples, different geographic coverage areas 110 associated with different technologies can overlap, and overlapping geographic coverage areas 110 associated with different technologies can be supported by the same base station 105 or different base stations 105. The wireless communication system 100 can include, for example, heterogeneous LTE / LTE-A / LTE-APro or NR networks, wherein different types of base stations 105 provide coverage for various geographic coverage areas 110.

[0045] The term "cell" refers to a logical communication entity used to communicate with base station 105 (e.g., via a carrier) and may be associated with an identifier (e.g., Physical Cell Identifier (PCID), Virtual Cell Identifier (VCID)) used to distinguish adjacent cells operating via the same or different carriers. In some examples, a carrier may support multiple cells and may be configured with different cell types based on different protocol types that can provide access to different types of devices (e.g., Machine-Type Communication (MTC), Narrowband Internet of Things (NB-IoT), Enhanced Mobile Broadband (eMBB), or others). In some cases, the term "cell" may refer to a portion (e.g., a sector) of a geographic coverage area 110 on which the logical entity operates.

[0046] User equipment 115 may be distributed throughout the wireless communication system 100, and each user equipment 115 may be stationary or mobile. User equipment 115 may also be referred to as a mobile device, wireless device, remote device, handheld device, or subscription user equipment, or some other suitable term, wherein "device" may also be referred to as a unit, station, terminal, or client. User equipment 115 may be a personal electronic device, such as a cellular phone, personal digital assistant (PDA), tablet computer, laptop computer, or personal computer. In some examples, user equipment 115 may also refer to a wireless local loop (WLL) station, Internet of Things (IoT) device, Internet of Everything (IoE) device, or MTC device, which may be implemented in various items such as appliances, vehicles, and meters.

[0047] Some user equipment 115, such as MTC or IoT devices, can be low-cost or low-complexity devices and can provide automated communication between machines (e.g., via machine-to-machine (M2M) communication). M2M communication or MTC can refer to data communication technologies that allow devices to communicate with each other or with base station 105 without human intervention. In some examples, M2M communication or MTC can include communication from devices integrated with sensors or meters to measure or capture information and relay that information to a central server or application, which can then utilize the information or present it to people interacting with it. Some user equipment 115 can be designed to collect information or enable automated machine behavior. Examples of applications for MTC devices include smart metering, inventory monitoring, water level monitoring, facility monitoring, healthcare monitoring, wildlife monitoring, weather and geological event monitoring, fleet management and tracking, remote security sensing, physical access control, and transaction-based billing.

[0048] Some user equipment 115 can be configured to operate in a power-saving mode, such as half-duplex communication (e.g., a mode that supports unidirectional communication via transmission or reception but not simultaneous transmission and reception). In some examples, half-duplex communication may be performed at a reduced peak rate. Other power-saving techniques for user equipment 115 include entering a power-efficient “deep sleep” mode when not engaged in active communication, or operating on limited bandwidth (e.g., according to narrowband communication). In some cases, user equipment 115 may be designed to support critical functions (e.g., mission-critical functions), and wireless communication system 100 may be configured to provide ultra-reliable communication for these functions.

[0049] In some cases, user equipment 115 may also be able to communicate directly with other user equipment 115 (e.g., using peer-to-peer (P2P) or device-to-device (D2D) protocols). One or more of a group of user equipment 115 utilizing D2D communication may be within the geographic coverage area 110 of base station 105. Other user equipment 115 in such a group may be outside the geographic coverage area 110 of base station 105 or may not be able to receive transmitted content from base station 105. In some cases, multiple groups of user equipment 115 communicating via D2D communication may utilize a one-to-many (1:M) system, where each user equipment 115 transmits to every other user equipment 115 in the group. In some cases, base station 105 facilitates resource scheduling for D2D communication. In other cases, D2D communication is performed between user equipment 115 without the participation of base station 105.

[0050] Base station 105 can communicate with the core network 130 and with each other. For example, base station 105 can interface with the core network 130 via backhaul link 132 (e.g., via S1, N2, N3 or other interfaces). Base station 105 can communicate with each other directly (e.g., directly between base stations 105) or indirectly (e.g., via core network 130) via backhaul link 134 (e.g., via X2, Xn or other interfaces).

[0051] The core network 130 can provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The core network 130 can be an evolved packet core (EPC), which may include at least one mobility management entity (MME), at least one serving gateway (S-GW), and at least one packet data network (PDN) gateway (P-GW). The MME can manage non-access stratum (e.g., control plane) functions, such as mobility, authorization, and bearer management of user equipment 115 served by base station 105 associated with the EPC. User IP packets can be transmitted through the S-GW, which itself can be connected to the P-GW. The P-GW can provide IP address allocation and other functions. The P-GW can be connected to the network operator's IP services. The P-GW operator's IP services may include access to the Internet, intranets, IP Multimedia Subsystem (IMS), or packet-switched (PS) streaming services.

[0052] At least some network devices, such as base station 105, may include sub-components, such as access network entities, which may be examples of access node controllers (ANCs). Each access network entity can communicate with user equipment 115 through multiple other access network transmitting entities, which may be referred to as radio headends, smart radio headends, or transmit / receive points (TRPs). In some configurations, the various functions of each access network entity or base station 105 may be distributed across various network devices (e.g., radio headends and access network controllers) or combined into a single network device (e.g., base station 105).

[0053] Wireless communication system 100 can operate using one or more frequency bands, typically in the range of 300 MHz to 300 GHz. The region from 300 MHz to 3 GHz is generally referred to as the Ultra High Frequency (UHF) region or decimeter band because this wavelength range is from approximately 1 decimeter to 1 meter in length. UHF waves may be blocked or deflected by buildings and environmental features. However, the waves can penetrate structures sufficiently to enable macrocells to provide service to user equipment 115 located indoors. UHF wave transmission can be associated with smaller antennas and shorter distances (e.g., less than 100 km) compared to transmissions using smaller frequencies and longer waves in the High Frequency (HF) or Very High Frequency (VHF) portions of the spectrum below 300 MHz.

[0054] The wireless communication system 100 can also operate in the ultra-high frequency (SHF) region using a frequency band from 3 GHz to 30 GHz (also known as the centimeter wave band). This SHF region includes frequency bands such as the 5 GHz Industrial, Scientific and Medical (ISM) band, which can be used as appropriate by devices capable of tolerating interference from other users.

[0055] The wireless communication system 100 can also operate in the extremely high frequency (EHF) region of this spectrum (e.g., from 30 GHz to 300 GHz), also known as the millimeter wave band. In some examples, the wireless communication system 100 can support millimeter wave (mmW) communication between user equipment 115 and base station 105, and the EHF antennas of the respective equipment can be smaller and more closely spaced than UHF antennas. In some cases, this can facilitate the use of antenna arrays within user equipment 115. However, compared to SHF or UHF transmissions, EHF transmissions may be more susceptible to greater atmospheric attenuation and shorter distances. The techniques disclosed herein can be used in transmissions using one or more different frequency regions, and the designated use of frequency bands in these frequency regions may vary by country or regulatory body.

[0056] In some cases, wireless communication system 100 may utilize licensed and unlicensed radio frequency spectrum bands. For example, wireless communication system 100 may employ Licensed Assisted Access (LAA), unlicensed LTE (LTE-U) radio access technology, or NR technology in unlicensed bands such as the 5 GHz ISM band. When operating in unlicensed radio frequency spectrum bands, wireless devices such as base station 105 and user equipment 115 may employ a Listen-After-Talk (LBT) procedure to ensure that the frequency channel is open before transmitting data. In some cases, operation in unlicensed bands may be based on carrier aggregation configuration and component carriers operating in licensed bands (e.g., LAA). Operation in unlicensed spectrum may include downlink transmission, uplink transmission, peer-to-peer transmission, or a combination thereof. Duplexing in unlicensed spectrum may be based on Frequency Division Duplex (FDD), Time Division Duplex (TDD), or a combination of both.

[0057] In some examples, base station 105 or user equipment 115 may be equipped with multiple antennas, which can be used to employ techniques such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communication, or beamforming. For example, wireless communication system 100 may use a transmission scheme between a transmitting device (e.g., base station 105) and a receiving device (e.g., user equipment 115), wherein the transmitting device is equipped with multiple antennas and the receiving device is equipped with one or more antennas. MIMO communication can employ multipath signal propagation, improving spectral efficiency by transmitting or receiving multiple signals via different spatial layers, which can be referred to as spatial multiplexing. For example, the multiple signals may be transmitted by the transmitting device via different antennas or different combinations of antennas. Similarly, the receiving device may receive the multiple signals via different antennas or different combinations of antennas. Each of the multiple signals may be referred to as a separate spatial stream and may carry bits associated with the same data stream (e.g., the same codeword) or different data streams. Different spatial layers may be associated with different antenna ports used for channel measurement and reporting. MIMO technology includes single-user MIMO (SU-MIMO) (where multiple spatial layers are sent to the same receiving device) and multi-user MIMO (MU-MIMO) (where multiple spatial layers are sent to multiple devices).

[0058] Beamforming, also known as spatial filtering, directional transmission, or directional reception, is a signal processing technique used at a transmitting or receiving device (e.g., base station 105 or UE 115) to shape or manipulate an antenna beam (e.g., a transmit beam or a receive beam) along a spatial path between the transmitting and receiving devices. Beamforming can be achieved by combining signals transmitted via antenna elements of an antenna array such that signals propagating in a particular direction relative to the antenna array experience constructive interference, while other signals experience destructive interference. The adjustment of the signals transmitted via the antenna elements can include the transmitting or receiving device applying specific amplitude and phase offsets to the carried signals via each antenna element associated with that device. The adjustment associated with each antenna element can be defined by a beamforming weight set associated with a particular direction (e.g., relative to the antenna array of the transmitting or receiving device, or relative to some other direction).

[0059] In one example, base station 105 may use multiple antennas or antenna arrays to perform beamforming operations for directional communication with user equipment 115. For example, some signals (e.g., synchronization signals, reference signals, beam selection signals, or other control signals) may be transmitted multiple times by base station 105 in different directions, which may include transmitting signals according to different beamforming weight sets associated with different transmission directions. Transmissions in different beam directions can be used to identify (e.g., by base station 105 or receiving equipment, such as user equipment 115) the beam directions used for subsequent transmissions and / or receptions by base station 105.

[0060] Some signals, such as data signals associated with a particular receiving device, may be transmitted by base station 105 in a single beam direction (e.g., the direction associated with that receiving device, such as user equipment 115). In some examples, the beam direction associated with transmission along a single beam direction may be determined at least in part based on signals transmitted in different beam directions. For example, user equipment 115 may receive one or more signals transmitted by base station 105 in different directions, and user equipment 115 may report to base station 105 an indication of the highest signal quality or other acceptable signal quality received. Although these techniques are described with reference to signals transmitted by base station 105 in one or more directions, user equipment 115 may employ similar techniques to transmit signals multiple times in different directions (e.g., to identify the beam direction that user equipment 115 subsequently transmits or receives), or to transmit signals in a single direction (e.g., to transmit data to a receiving device).

[0061] When receiving various signals, such as synchronization signals, reference signals, beam selection signals, or other control signals, from the base station 105, a receiving device (e.g., user equipment 115, which may be an example of a millimeter-wave receiving device) can attempt multiple receiving beams. For example, the receiving device can attempt multiple receiving directions, depending on the receiving beam or direction, by receiving via different antenna subarrays, by processing the received signal according to different antenna subarrays, by receiving according to different sets of receiving beamforming weights applied to the signal received at a set of antenna elements of the antenna array, or by processing the received signal according to different sets of receiving beamforming weights applied to the signal received at a set of antenna elements of the antenna array. These can all be referred to as "listening." In some examples, the receiving device can use a single receiving beam to receive along a single beam direction (e.g., when receiving data signals). This single receiving beam can be aligned at least in part based on a beam direction determined by listening according to different receiving beam directions (e.g., determined to have the highest signal strength, the highest signal-to-noise ratio, or at least in part based on an acceptable signal quality based on listening according to multiple beam directions).

[0062] In some cases, the antennas of base station 105 or user equipment 115 may be located within one or more antenna arrays that can support MIMO operation or transmit / receive beamforming. For example, one or more base station antennas or antenna arrays may be located together at an antenna assembly, such as an antenna tower. In some cases, the antennas or antenna arrays associated with base station 105 may be located in different geographical locations. Base station 105 may have an antenna array with multiple rows and columns of antenna ports that it can use to support beamforming for communication with user equipment 115. Similarly, user equipment 115 may have one or more antenna arrays that can support various MIMO or beamforming operations.

[0063] In some cases, the wireless communication system 100 may be a packet-based network operating according to a layered protocol stack. In the user plane, communication at the bearer layer or Packet Data Convergence Protocol (PDCP) layer may be IP-based. The Radio Link Control (RLC) layer may perform packet segmentation and reassembly for communication on logical channels. The MAC layer may perform priority processing and multiplex logical channels into transmit channels. The MAC layer may also use Hybrid Automatic Repeat Request (HARQ) to provide retransmission at the MAC layer to improve link efficiency. In the control plane, the Radio Resource Control (RRC) protocol layer may provide the establishment, configuration, and maintenance of RRC connections between user equipment 115 and base station 105 or core network 130 supporting user plane data radio bearers. In the physical layer, transport channels may be mapped to physical channels.

[0064] In some cases, user equipment 115 and base station 105 may support data retransmission to increase the likelihood of successful data reception. HARQ feedback is a technique to increase the likelihood of correct data reception via communication link 125. HARQ may include a combination of error detection (e.g., using Cyclic Redundancy Check (CRC)), forward error correction (FEC), and retransmission (e.g., Automatic Repeat Request (ARQ)). HARQ can improve throughput at the MAC layer under poor radio conditions (e.g., signal-to-noise ratio conditions). In some cases, the wireless device may support simultaneous time-slot HARQ feedback, where the device can provide HARQ feedback in a specific time slot for data received in the previous symbol within that time slot. In other cases, the device can provide HARQ feedback in subsequent time slots or according to other time intervals.

[0065] In LTE or NR, time intervals can be expressed as multiples of a basic time unit, such as T. s = 1 / 30,720,000 second sampling period. The time interval of the communication resource can be organized according to radio frames, where each radio frame has a duration of 10 milliseconds (ms), and the frame period can be expressed as Tf = 307,200 Ts. The radio frame can be identified by a System Frame Number (SFN) ranging from 0 to 1023. Each frame can include 10 subframes numbered from 0 to 9, and each subframe can have a duration of 1 ms. The subframe can be further divided into 2 time slots, where each time slot has a duration of 0.5 ms, and each time slot can contain 6 or 7 modulation symbol periods (e.g., depending on the length of the cyclic prefix pre-added to each symbol period). Removing the cyclic prefix, each symbol period can contain 2048 sampling periods. In some cases, the subframe can be the smallest scheduling unit of the wireless communication system 100 and can be referred to as the Transmission Time Interval (TTI). In other cases, the minimum scheduling unit of the wireless communication system 100 may be shorter than a subframe, or may be dynamically selected (e.g., in a burst of shortened TTI (sTTI), or in a selected component carrier using sTTI).

[0066] In some wireless communication systems, a time slot can be divided into multiple mini-slots containing one or more symbols. In some cases, a symbol in a mini-slot or a mini-slot can be the smallest scheduling unit. For example, the duration of each symbol can vary depending on the subcarrier spacing or the frequency band of operation. Furthermore, some wireless communication systems can implement time slot aggregation, where multiple time slots or mini-slots are aggregated together and used for communication between user equipment 115 and base station 105.

[0067] The term "carrier" refers to a set of radio frequency spectrum resources with a defined physical layer structure used to support communication on communication link 125. For example, a carrier of communication link 125 may include a portion of a radio frequency spectrum band operating according to a physical layer channel of a given radio access technology. Each physical layer channel may carry user data, control information, or other signaling. Carriers may be associated with predefined frequency channels (e.g., Evolved Universal Mobile Telecommunications System Terrestrial Radio Access (E-UTRA) Absolute Radio Frequency Channel Number (EARFCN)) and can be located according to a channel grid for discovery by user equipment 115. Carriers may be downlink or uplink (e.g., in FDD mode) or configured to carry both downlink and uplink communication (e.g., in TDD mode). In some examples, the signal waveform transmitted via a carrier may consist of multiple subcarriers (e.g., using multi-carrier modulation (MCM) techniques such as Orthogonal Frequency Division Multiplexing (OFDM) or Discrete Fourier Transform Extended OFDM (DFT-S-OFDM).

[0068] The organization of a carrier may differ depending on the radio access technology (e.g., LTE, LTE-A, LTE-A Pro, NR). For example, communication on a carrier can be organized according to TTIs or time slots, each of which may include user data and control information or signaling supporting the decoding of that user data. A carrier may also include dedicated acquisition signaling (e.g., synchronization signals or system information) and control signaling coordinating the operation of that carrier. In some examples (e.g., in a carrier aggregation configuration), a carrier may also have acquisition signaling or control signaling coordinating the operation of other carriers.

[0069] Depending on the technology used, physical channels can be multiplexed on carriers. Physical control channels and physical data channels can be multiplexed on downlink carriers, for example, using time division multiplexing (TDM), frequency division multiplexing (FDM), or hybrid TDM-FDM techniques. In some examples, control information transmitted in the physical control channel can be distributed in a cascaded manner between different control regions (e.g., between a common control region or common search space and one or more user equipment-specific control regions or user equipment-specific search spaces).

[0070] A carrier can be associated with a specific bandwidth of the radio frequency spectrum, and in some examples, this carrier bandwidth can be referred to as the “system bandwidth” of the carrier or the wireless communication system 100. For example, the carrier bandwidth can be one of several predetermined bandwidths of a carrier for a particular radio access technology (e.g., 1.4, 3, 5, 10, 15, 20, 40, or 80 MHz). In some examples, each served user equipment 115 can be configured to operate on part or all of the carrier bandwidth. In other examples, some user equipment 115 can be configured to operate using a narrowband protocol type associated with a predetermined portion or range (e.g., a set of subcarriers or RBs) within the carrier (e.g., “in-band” deployment of a narrowband protocol type).

[0071] In a system employing MCM technology, a resource element can consist of a symbol period (e.g., the duration of a modulation symbol) and a subcarrier, where the symbol period and subcarrier spacing are inversely related. The number of bits carried by each resource element can depend on the modulation scheme (e.g., the order of the modulation scheme). Therefore, the more resource elements received by user equipment 115, and the higher the order of the modulation scheme, the higher the data rate of user equipment 115 may be. In a MIMO system, wireless communication resources can refer to a combination of radio frequency spectrum resources, temporal resources, and spatial resources (e.g., spatial layers), and the use of multiple spatial layers can further increase the data rate of communication with user equipment 115.

[0072] The devices of the wireless communication system 100 (e.g., base station 105 or user equipment 115) may have a hardware configuration that supports communication on a specific carrier bandwidth, or may be configured to support communication on one of a set of carrier bandwidths. In some examples, the wireless communication system 100 may include base station 105 and / or user equipment 115 that support simultaneous communication via carriers associated with more than one different carrier bandwidth.

[0073] The wireless communication system 100 can support communication with user equipment 115 on multiple cells or carriers; this feature can be referred to as carrier aggregation or multi-carrier operation. Depending on the carrier aggregation configuration, user equipment 115 can be configured with multiple downlink component carriers and one or more uplink component carriers. Carrier aggregation can be used in conjunction with FDD and TDD component carriers.

[0074] In some cases, the wireless communication system 100 may utilize enhanced component carriers (eCC). eCC has one or more characteristics, including wider carrier or frequency channel bandwidth, shorter symbol duration, shorter TTI duration, or modified control channel configuration. In some cases, eCC may be associated with carrier aggregation configurations or dual connectivity configurations (e.g., when multiple serving cells have suboptimal or non-ideal backhaul links). eCC may also be configured for unlicensed spectrum or shared spectrum (e.g., where more than one operator is permitted to use the spectrum). eCC characterized by wide carrier bandwidth may include one or more segments that can be used by user equipment 115 that cannot monitor the entire carrier bandwidth or is configured to use limited carrier bandwidth (e.g., for energy saving).

[0075] In some cases, eCC can utilize symbol durations different from those of other component carriers, which may include using a reduced symbol duration compared to that of other component carriers. The shorter symbol duration can be associated with increased spacing between adjacent subcarriers. Devices utilizing eCC, such as user equipment 115 or base station 105, can transmit wideband signals (e.g., based on frequency channels or carrier bandwidths of 20, 40, 60, 80 MHz, etc.) with a reduced symbol duration (e.g., 16.67 microseconds). The TTI in eCC can consist of one or more symbol periods. In some cases, the TTI duration (i.e., the number of symbol periods in the TTI) can be variable.

[0076] The wireless communication system 100 can be an NR system, which can utilize any combination of licensed, shared, and unlicensed spectrum bands, etc. Flexibility in eCC symbol duration and subcarrier spacing allows for the use of eCC across multiple spectrums. In some examples, NR spectrum sharing can improve spectrum utilization and efficiency, particularly through dynamic vertical (e.g., across frequency domains) and horizontal (e.g., across time domains) sharing of resources.

[0077] User equipment 115 attempting to access a wireless network can perform an initial cell search by detecting the primary synchronization signal (PSS) from base station 105. The PSS enables synchronization of time slot timing and indicates a physical layer identity value. User equipment 115 can then receive an auxiliary synchronization signal (SSS). The SSS enables radio frame synchronization and provides a cell identification value, which can be combined with the physical layer identification value to identify the cell. The SSS also enables detection of duplex mode and cyclic prefix length. Some systems, such as TDD systems, can transmit an SSS but not a PSS. The PSS and SSS can be located in the center 62 and 72 subcarriers of the carrier, respectively. In some cases, base station 105 can use multiple beams to transmit synchronization signals (e.g., PSS, SSS, etc.) in a beam-scanning manner over the cell coverage area. In some cases, the PSS, SSS, and / or broadcast information (e.g., the Physical Broadcast Channel (PBCH)) can be transmitted in different synchronization signal (SS) blocks on their respective directional beams, where one or more SS blocks can be included in an SS burst.

[0078] After receiving the PSS and SSS, the user equipment 115 can receive the Master Information Block (MIB), which can be transmitted in the PBCH. The MIB may contain system bandwidth information, SFN, and Physical HARQ Indicator Channel (PHICH) configuration. After decoding the MIB, the user equipment 115 can receive one or more System Information Blocks (SIBs). For example, SIB1 may contain cell access parameters and scheduling information for other SIBs. Decoding SIB1 enables the user equipment 115 to receive SIB2. SIB2 may contain RRC configuration information related to RACH procedures, paging, PUCCH, PUSCH, power control, SRS, and cell bar.

[0079] After initial cell synchronization is completed, User Equipment 115 can decode the MIB, SIB1, and SIB2 before accessing the network. The MIB can be transmitted on the PBCH and can utilize the first four OFDMA symbols of the second time slot of the first subframe of each radio frame. The MIB can use the middle six RBs (72 subcarriers) in this frequency domain. The MIB carries important information for initial access by the User Equipment, including downlink channel bandwidth for the RBs, PHICH configuration (duration and resource allocation), and SFN. The new MIB can be broadcast every four radio frames (SFN mod 4 = 0) and replayed every frame (10 ms). Each repetition is scrambled with a different scrambling code.

[0080] After reading the MIB (new version or copy), the user equipment 115 can try different phases of the scrambling code until it achieves a successful CRC check. The phase of the scrambling code (0, 1, 2, or 3) allows the user equipment 115 to identify which of the four repetitions has been received. Therefore, the user equipment 115 can determine the current SFN by reading the decoded SFN and adding the scrambling code phase. After receiving the MIB, the user equipment can receive one or more SIBs. Different SIBs can be defined depending on the type of system information being transmitted. A new SIB1 can be sent in the fifth subframe every eight frames (SFN mod 8 = 0) and rebroadcast every other frame (20 ms). SIB1 includes access information, including cell identity information, and can indicate whether a user equipment is allowed to camp on the cell. SIB1 also includes cell selection information (or cell selection parameters). In addition, SIB1 includes scheduling information for other SIBs. SIB2 can be dynamically scheduled based on the information in SIB1, and SIB2 includes access information and parameters related to the shared channel. The period of SIB2 can be set to 8, 16, 32, 64, 128, 256 or 512 radio frames.

[0081] After user equipment 115 decodes SIB2, it can send a RACH preamble (e.g., message 1 (Msg1) in a four-step RACH process) to base station 105. For example, the RACH preamble can be randomly selected from a set of 64 predetermined sequences. This random selection allows base station 105 to distinguish between multiple user equipment 115s attempting to access the system simultaneously. Base station 105 can respond with a random access response (e.g., a second message (Msg2)) that provides uplink resource grant, timing advance, and temporary cell radio network temporary identifier (C-RNTI). User equipment 115 can then send an RRC connection request (e.g., a third message (Mg3)) along with a temporary mobile subscription subscriber identifier (TMSI) (if user equipment 115 has previously connected to the same wireless network) or a random identifier. The RRC connection request can also indicate the reason for user equipment 115's connection to the network (e.g., emergency, signaling, data exchange, etc.). The base station 105 can respond to the connection request with a contention resolution message (e.g., a fourth message (Msg4)) addressed to the user equipment 115, which can provide a new C-RNTI. If the user equipment 115 receives a contention resolution message with the correct identifier, the user equipment 115 can continue with RRC setup. If the user equipment 115 does not receive a contention resolution message (e.g., if there is a conflict with another user equipment 115), it can repeat the RACH process by sending a new RACH preamble. This exchange of messages for random access between the user equipment 115 and the base station 105 can be referred to as a four-step RACH process.

[0082] In other examples, a two-step RACH procedure can be performed for random access. For example, a wireless device operating in licensed or unlicensed spectrum within wireless communication system 100 can initiate a two-step RACH procedure to reduce the latency of establishing communication with base station 105 (e.g., compared to a four-step RACH procedure). In some cases, the two-step RACH procedure can operate regardless of whether the wireless device (e.g., user equipment 115) has a valid timing advance (TA). For example, user equipment 115 can use a valid TA to coordinate the timing of its transmissions to base station 105 (e.g., considering propagation delay) and can receive that valid TA as part of the two-step RACH procedure. Furthermore, the two-step RACH procedure can be applied to any cell size and can work regardless of whether the RACH procedure is contention-based or contention-free, and multiple RACH messages from a four-step RACH procedure can be combined. For example, the two-step RACH process may include a first message (e.g., message A (MsgA)) and a second message (e.g., message B (MsgB)), the first message combining Msg1 and Msg3 in the four-step RACH process, and the second message combining Msg2 and Msg4 in the four-step RACH process.

[0083] This two-step RACH procedure can be applied to any cell size supported by the wireless communication system, can operate regardless of whether the user equipment 115 has effective timing advance (TA), and can be applied to any RRC state of the user equipment 115 (e.g., idle state (RRC_IDLE), inactive state (RRC_INACTIVE), connected state (RRC_CONNECTED), etc.). In some cases, this two-step RACH procedure can reduce signaling overhead and latency, enhance RACH capacity, save power for the user equipment 115, and provide coordination with other applications (e.g., positioning, mobility enhancement, etc.).

[0084] In some cases, for base station 105 (e.g., serving cell), a first set of periodic channel state information (CSI) reference signal (CSI-RS) resource configuration indexes (q0) can be provided to user equipment 115 through a first higher-layer parameter (e.g., failureDetectionResources), and a second set of periodic CSI-RS resource configuration indexes and / or SS / PBCH block indexes (q1) can be provided to user equipment 115 through a second higher-layer parameter (e.g., candidateBeamRSList) for radio link quality measurement of base station 105. Additionally or alternatively, if the first higher-layer parameter is not provided to the user equipment 115, the user equipment 115 may determine that the set q0 includes an SS / PBCH block index and a periodic CSI-RS resource configuration index having the same values ​​as the reference signal indexes in the reference signal set, the reference signal set being indicated by the transmit configuration indicator (TCI) status of the respective control resource set (CORESET), which the user equipment 115 uses to monitor downlink channels (e.g., physical downlink control channel (PDCCH)). The user equipment 115 may expect the set q0 to include up to two reference signal indices, and if two RS indices exist, the set q0 includes reference signal indices with quasi-cooperative positioning (QCL type)-type D configuration for the corresponding TCI status. Furthermore, the user equipment 115 may expect single-port reference signals in the set q0.

[0085] Based on set q0, user equipment 115 can monitor the set of reference signals within set q0 for beam fault detection as part of a beam fault recovery process to improve the robustness of communication with base station 105. For the beam fault recovery process, user equipment 115 can detect beam faults, identify new candidate beams, send a beam fault recovery request to base station 105, and monitor the response from base station 105 to the beam fault recovery response. Therefore, as part of detecting the beam fault, user equipment 115 can monitor the maximum set of reference signals belonging to set q0. In some cases, the maximum number of reference signal sets can be two (2), although a greater number of reference signal sets can be used. As described above, user equipment 115 can determine set q0 based on reference signals from the core sets used for monitoring activities (e.g., the set of reference signals used by user equipment 115 to monitor the TCI status indications of the various core sets of the PDCCH). In some cases, the user equipment 115 may perform a RACH procedure (e.g., contention-based random access (CBRA), four-step RACH, two-step RACH, etc.) as part of the beam fault recovery process to re-establish a connection with the base station 105.

[0086] In some wireless communications, base station 105 (e.g., a network) can configure a MAC CE for user equipment 115 to report a new preferred beam after a beam fault is triggered on a SCell cell. For example, this new MAC CE may include an index of the SCell cell where the beam fault was triggered and an index of the new preferred beam for that SCell cell. In some cases, this new MAC CE may be referred to as a beam index indication MAC CE. However, conventionally, the user equipment may not know which uplink resources to use to send the beam index indication, and / or may not fully utilize a subset of the beam index indications in the process.

[0087] The wireless communication system 100 can support beam index indication for transmitting a new preferred beam on uplink resources based on uplink resource availability, and efficient techniques for transmitting the beam index indication for different communication establishment scenarios. For example, if the user equipment 115 determines to establish the communication link and identifies the new preferred beam, the uplink resources are scheduled and... If the uplink resource is available within a time slot, the user equipment 115 can multiplex the beam index indication with the MAC PDU transmitted on that uplink resource. Alternatively, if the uplink resource is unavailable, the user equipment 115 can request additional uplink resources (e.g., based on configured uplink channel resources, via a scheduling request, etc.) to transmit the beam index indication. Furthermore, the user equipment 115 can transmit the beam index indication for beam failure recovery procedures as described above and for RACH procedures to establish communication with at least one cell of the base station 105. Therefore, the user equipment 115 can transmit the beam index indication in messages of the RACH procedure (e.g., the first message in a two-step RACH procedure, the connection request / third message in a four-step RACH procedure).

[0088] Figure 2 An example of a wireless communication system 200 supporting a beam index indication MAC procedure according to various aspects of this disclosure is shown. In some examples, the wireless communication system 200 may implement various aspects of the wireless communication system 100. The wireless communication system 200 may include a base station 105-a and a user equipment 115-a, which may be examples of corresponding base station 105 and user equipment 115, as referenced above. Figure 1 As described herein, base station 105-a and user equipment 115-a can communicate with each other using beamforming technology. For example, base station 105-a can use one or more beams 205 to transmit downlink signals to user equipment 115-a and / or receive uplink signals from user equipment 115-a. Furthermore, user equipment 115-a can use one or more beams 210 to transmit uplink signals to base station 105-a and / or receive downlink signals from base station 105-a. In some cases, user equipment 115-a can communicate with base station 105-a via one or more cells on base station 105-a (e.g., PCell, SCell, PSCell, SPCell, etc.).

[0089] In some cases, user equipment 115-a can identify a beam fault triggered on a cell (e.g., SCell) of base station 105-a. User equipment 115-a can then measure the link quality of one or more candidate beams configured for the cell where the beam fault was detected. For example, user equipment 115-a can measure the link quality of individual beams 205-a, 205-b, and 205-c transmitted by base station 105-a (e.g., by measuring a reference signal on each beam 205). In some cases, if this measurement is not readily available (e.g., if user equipment 115-a has not recently measured or has never measured link quality), user equipment 115-a can perform the link quality measurement.

[0090] Therefore, once the measurement is available, beam indication 215 (e.g., beam index indication) can be triggered. That is, user equipment 115-a can select beam 205 transmitted by base station 105-a based on this link quality measurement, which beam 205 is preferred for subsequent downlink transmissions (e.g., beam fault recovery procedures). For example, user equipment 115-a can select beam 205-b (e.g., preferred beam) for base station 105-a to perform beam fault recovery procedures based on beam 205-b having the best signal quality (e.g., strongest received signal, least interference, etc.) compared to beams 205-a and 205-c. After beam indication 215 (e.g., indicating beam 205-b) is triggered, a MAC CE (e.g., beam index indication MAC CE) carrying beam indication 215 is generated when uplink resources become available, and this MAC CE carrying beam indication 215 is transmitted to base station 105-a (e.g., the network).

[0091] Therefore, if there is a future in If an upcoming uplink resource is scheduled within a time slot (e.g., or another TTI of length), then user equipment 115-a can multiplex the MAC CE carrying beam indication 215 in that MAC PDU, which will be transmitted through that uplink resource. In some cases, this can be configured (e.g., via RRC signaling) or defined (e.g., predefined for base station 105-a and user equipment 115-a). Furthermore, the uplink resource can be dynamically licensed or configured to be licensed. Subsequently, user equipment 115-a can transmit beam indication 215 to base station 105-a on that uplink resource (e.g., based on the MAC CE carrying beam indication 215 multiplexed in that MAC PDU).

[0092] Alternatively, if no uplink resource is readily available, or if the uplink resource appears too late to signal the MAC CE carrying beam indication 215 (e.g., recovering a faulty beam and performing the beam fault recovery process may require low latency), user equipment 115-a can request uplink resources via an uplink channel (e.g., the Physical Uplink Control Channel (PUCCH)). For example, base station 105-a can configure uplink channel resources dedicated to beam fault recovery processes. Therefore, when beam indication 215 is triggered, user equipment 115-a can use at least one valid opportunity of this dedicated uplink channel resource to direct (e.g., request) base station 105-a to signal new uplink resources at the physical layer (e.g., using new uplink resources to transmit the MAC CE carrying beam indication 215). This signal (e.g., the signal of the new uplink resource) can be a known sequence of symbols configured for user equipment 115-a (e.g., a TTI of different lengths).

[0093] Alternatively or concurrently, instead of using the dedicated uplink channel, user equipment 115-a can transmit a sequence of scheduling requests (e.g., initiate a scheduling request) through uplink channel resources (e.g., PUCCH resources) configured to request uplink resources to send an indication of a selected first beam to base station 105-a. In some cases, the scheduling request can be used by user equipment 115-a to signal the arrival of new data, which base station 105-a can then provide uplink resources for. Furthermore, base station 105-a can configure different sets of uplink channel resources for different data logical channels based on the priority of the configured data logical channels. Therefore, in order for a failed beam to recover quickly (e.g., a faster beam failure recovery process), the scheduling request for the MAC CE carrying beam indication 215 can be transmitted through the uplink channel resources allocated to the data logical channel configured for user equipment 115-a with the highest priority. In some cases, user equipment 115-a may request the uplink resources for transmitting beam indication 215 based on performing a RACH procedure. For example, after experiencing a beam failure on a cell (e.g., serving cell, SCell, PCell, SPCell, PSCell, etc.), user equipment 115-a may perform a RACH procedure to reconnect to the cell. As part of the RACH procedure, or once the RACH procedure is completed, user equipment 115-a may request uplink resources from the cell, which can be used to transmit beam indication 215.

[0094] When sending the scheduling request to request uplink resources for transmitting beam indication 215 (e.g., beam indication 215 of the selected first beam), user equipment 115-a may send a one-bit indication to base station 105-a (e.g., the network) to indicate that uplink resources have been requested. Furthermore, base station 105-a may configure multiple scheduling request configurations for user equipment 115-a to send the scheduling request, enabling user equipment 115-a to send the scheduling request via uplink resources (e.g., PUCCH resources) in different scheduling request configurations. For example, user equipment 115-a may use one of the different scheduling request configurations based on the priority of the data that triggered the scheduling request, wherein the mapping of different data priorities to the different scheduling request configurations (e.g., which scheduling request configuration can be used for an indication of the priority of each data) is configured by base station 105-a. However, User Equipment 115-a may not be able to indicate which serving cell (e.g., one or more SCells)'s uplink resources it wants to use for transmitting Beam Indication 215 (e.g., which serving cells have beams capable of supporting Beam Indication 215). For example, because Base Station 105-a does not know that the scheduling request is for a beam failure recovery process (e.g., if no dedicated PUCCH resources have been allocated for this purpose) or which serving cell the beam failure occurred on, Base Station 105-a may send a downlink message (e.g., Downlink Control Information (DCI)) to grant the requested uplink resources on the failed downlink (e.g., PDCCH) beam. Therefore, User Equipment 115-a may not receive permission to send the beam failure indication MAC CE (e.g., the MAC CE carrying Beam Indication 215) on that uplink resource.

[0095] In some cases, to enable user equipment 115-a to receive an indication (e.g., permission) of the uplink resource to be used for transmitting the MAC CE carrying beam indication 215, base station 105-a (e.g., the network) can configure a dedicated PUCCH scheduling request for beam fault recovery. Therefore, when user equipment 115-a requests uplink resources for transmitting the MAC CE carrying beam indication 215 (e.g., beam fault recovery MAC CE), user equipment 115-a can transmit the scheduling request on one or more PUCCH resources (e.g., uplink resources) according to the dedicated PUCCH scheduling request configuration. For example, the dedicated PUCCH scheduling request configuration may include an indication of which PUCCH resource (e.g., time and / or frequency resources in the PUCCH) to transmit the scheduling request.

[0096] Subsequently, when base station 105-a receives the scheduling request (e.g., transmitted according to the dedicated PUCCH scheduling request configuration), base station 105-a can recognize that the scheduling request was triggered by the beam fault recovery process. Base station 105-a can then send the downlink message (e.g., DCI) to authorize the requested uplink resources for transmitting the MAC CE carrying beam indication 215 on a downlink channel (e.g., PDCCH) in a special cell (SpCell) configured for user equipment 115-a, where the requested uplink resources are also located in that SpCell. In some cases, the SpCell may include a PCell, a PSCell, or an additional cell configured for the primary communications of user equipment 115-a. By sending an indication of the uplink resource (e.g., permission for the uplink resource) on the SpCell, user equipment 115-a has a higher probability of receiving the indication of the uplink resource, given the impossibility of all downlink (e.g., PDCCH) beams in both the SpCell and SCell for user equipment 115-a failing simultaneously. However, if the downlink beam in the SpCell fails, user equipment 115-a can trigger a RACH-based recovery procedure to re-establish communication with the SpCell and can send a request for the uplink resource to send the MAC CE carrying beam indication 215 during the corresponding RACH procedure, and then send the MAC CE once the RACH procedure is complete.

[0097] Alternatively, a dedicated scheduling request configuration cannot be used for beam fault recovery procedures. Instead, user equipment 115-a can use a scheduling request configuration designed for conventional scheduling requests (e.g., triggered by new data as described above), but for the purpose of this beam fault recovery procedure. For example, each uplink control resource in the scheduling request configuration (e.g., the PUCCH resource used to send the scheduling request) can be associated with one or more different serving cells, where the mapping between serving cells and uplink control resources is one-to-one or many-to-one.

[0098] For example, for a one-to-one mapping, the uplink control resources in a first transmission instance (e.g., a first time slot, which may be time slot 0) can be associated with a first serving cell (e.g., serving cell 0), the uplink control resources in a second time slot (e.g., time slot 1) can be associated with a second serving cell (e.g., serving cell 1), and so on. In some cases, the uplink control resources in a time slot can be associated with multiple serving cells (e.g., the second time slot can be associated with the second serving cell, a third serving cell, and a fourth serving cell). Additionally or alternatively, for a many-to-one mapping, the uplink control resources in the first time slot (e.g., time slot 0) can be associated with any serving cell other than the first serving cell, the uplink control resources in the second time slot can be associated with any serving cell other than the second serving cell, and so on. In other words, for this many-to-one mapping, user equipment 115-a can indicate a set of serving cells (e.g., excluding the serving cell corresponding to the timeslot number) on which the requested uplink resources for transmitting the MAC CE bearing beam indication 215 can be allocated.

[0099] Therefore, when beam failure recovery is triggered on an SCell (e.g., a secondary serving cell), the MAC layer can trigger a scheduling request and send the scheduling request to the physical layer. Along with the scheduling request, the MAC layer can indicate which SCell(s) it needs to avoid for receiving the requested uplink resource (e.g., an uplink grant for that uplink resource) and subsequently sending the MAC CE carrying beam indication 215. In some cases, downlink beams (e.g., PDCCH beams) on multiple SCells may have the same QCL relationship (e.g., signals from the QCL SCell experience similar channel conditions and pass through similar channels, allowing user equipment 115-a to assume the signal originates from the same location), and based on this QCL relationship, user equipment 115-a can assume that these SCells may also fail together when a beam failure occurs. When the physical layer receives the scheduling request, it can send the scheduling request through any valid uplink control resource other than the uplink control resource associated with the SCell to be avoided (e.g., as indicated by the mapping scheme described above).

[0100] In some cases, both SpCells (e.g., pCell, PSCell, etc.) and SCells may fail (e.g., experience beam faults), which may affect how User Equipment 115-a performs beam fault recovery procedures and sends beam indication 215 (e.g., when the SCell fails as described above). For example, if the SpCell beam fault has already been triggered, and a corresponding RACH-based recovery (e.g., re-establishing communication with the SpCell) has been initiated when the SCell beam fault recovery is triggered, User Equipment 115-a may wait for the SpCell beam fault recovery (e.g., via RACH-based recovery) to complete before sending the MAC CE carrying beam indication 215 for the SCell beam fault recovery. Therefore, User Equipment 115-a may send the MAC CE carrying beam indication 215 based on the uplink clearance provided in the second RACH message (e.g., msg2) for the RACH used for the SpCell beam fault recovery.

[0101] Alternatively or consequently, if a beam failure occurs on the SCell before a beam failure occurs on the SpCell, user equipment 115-a may take different actions. For example, if user equipment 115-a has already triggered the scheduling request for beam failure recovery for the SCell (e.g., requesting uplink resources to send the MAC CE carrying beam indication 215) when beam failure recovery for the SpCell is triggered, user equipment 115-a may first perform beam failure recovery based on the RACH for the SpCell, and then send the MAC CE carrying beam indication 215 for the SCell beam failure recovery in the uplink clearance provided in the second message (e.g., msg2) of the RACH for the SpCell beam failure recovery. Additionally or alternatively, if the MAC CE for the SCell beam fault recovery has been sent when the SpCell beam fault recovery is triggered, but the base station 105-a has not yet reconfigured the downlink beam for the SpCell, then the user equipment 115-a may first perform the SpCell beam fault recovery (e.g., RACH-based recovery) before completing the beam fault recovery for the SCell.

[0102] In some cases, user equipment 115-a and / or base station 105-a configure timers and counters for SCell beam failure recovery, re-establishing the connection with the SCell via the indicated beam (e.g., the selected first beam) by transmitting the MAC CE carrying beam indication 215. Therefore, if base station 105-a does not reconfigure the downlink beam for the failed SCell before the configured timer expires, user equipment 115-a can retransmit the MAC CE carrying beam indication 215 (e.g., on the uplink resources requested by user equipment 115-a and / or indicated by base station 105-a, as described above). With each transmission / retransmission of the MAC CE carrying beam indication 215, user equipment 115-a can increment the counter by one (1) time and can continue to attempt to transmit the MAC CE until the counter's limit (e.g., a counter threshold) is reached. If the counter's limit is reached, a radio link failure may be triggered. In some cases, this radio link failure may cause user equipment 115-a to perform RACH to identify a new SCell for establishing a secondary communication link.

[0103] When using the MAC CE carrying beam indicator 215 for beam fault recovery, as described above, user equipment 115-a can (e.g., when the uplink resource is available) multiplex the MAC CE carrying beam indicator 215 into the MAC PDU. Furthermore, when the MAC CE carrying beam indicator 215 is multiplexed into the MAC PDU along with other data, the MAC CE carrying beam indicator 215 can be given high priority during logical channel prioritization (LCP) (e.g., to ensure rapid recovery of the faulty beam). The priority of the MAC CE carrying beam indicator 215 can be lower than common control channel (CCCH) messages, but higher than any additional logical channel MAC CEs and data.

[0104] In some implementations, the MAC CE carrying beam indication 215 can be used for additional purposes. For example, user equipment 115-a can indicate a preferred beam 205 (e.g., beam 205-b) during the RACH procedure. In some cases, user equipment 115-a can determine to perform the RACH procedure to establish an initial connection with base station 105-a, or to re-establish communication with base station 105-a's cell (e.g., PCell, PSCell, SPCell). Each physical RACH (PRACH) timing can be associated with a reference signal (e.g., a candidate beam for user equipment 115-a). By selecting the PRACH timing for transmitting the PRACH preamble, user equipment 115-a can indicate (e.g., implicitly) to base station 105-a which beam is preferred for use by base station 105-a to perform the remaining RACH procedure or transmit subsequent downlink signals. However, base station 105-a can be configured with up to 128 beams. Therefore, with a number of candidate beams 205 configured, user equipment 115-a may have to wait a long time to reach the PRACH timing of the 128 beams associated with the preferred beam (e.g., if the preferred beam is the last in time, or if the base station 105-a cycles through these beams of the PRACH timing later in time).

[0105] To reduce the waiting time of user equipment 115-a, user equipment 115-a can select a suitable beam to transmit the PRACH preamble, wherein the suitable beam is available faster than the preferred beam, but its signal quality may be lower than the preferred beam. User equipment 115-a can then indicate the preferred beam in the MAC CE carrying beam indication 215 after transmitting the PRACH preamble. In some cases, the MAC CE carrying beam indication 215 can be included in the payload of MsgA in a two-step RACH process (e.g., the Physical Uplink Shared Channel (PUSCH) payload), or in msg3 in a four-step RACH process.

[0106] Additionally or alternatively, to reduce access latency, User Equipment 115-a may initiate a RACH procedure before measuring the link quality of all reference signals. Therefore, once User Equipment 115-a finds a beam with suitable link quality for performing the RACH procedure, it can begin the RACH procedure. However, during the RACH procedure, User Equipment 115-a can continue measuring the link quality of the remaining beams. In some cases, if a better candidate beam is found during this continuous measurement process, User Equipment 115-a can indicate the latest preferred beam in the MAC CE carrying beam indication 215. Similar to the techniques described above, the MAC CE carrying beam indication 215 can be included in the payload of Msg3 in a four-step RACH procedure, the retransmitted MsgA in a two-step RACH procedure, etc. When using the suitable beam and / or continuing the link quality measurement, the multiplexing rules described above can be applied to increase the probability that the MAC CE carrying beam indication 215 is included in msgA or msg3.

[0107] Figure 3 An example of a processing flow 300 supporting a beam index indication MAC procedure according to various aspects of this disclosure is shown. In some examples, processing flow 300 may implement various aspects of wireless communication systems 100 and / or 200. Processing flow 300 may include base station 105-b and user equipment 115-b, which may be examples of corresponding base station 105 and user equipment 115, as referenced above. Figures 1 to 2 As described herein, base station 105-b and user equipment 115-b can communicate with each other using beamforming technology.

[0108] In the following description of the processing flow 300, operations between user equipment 115-b and base station 105-b may be transmitted in a different order than those shown, or the operations performed by base station 105-b and user equipment 115-b may be executed in a different order or at different times. Some operations may also be excluded from the processing flow 300, or other operations may be added to the processing flow 300. It should be understood that although base station 105-b and user equipment 115-b are shown performing multiple operations of processing flow 300, any wireless device can perform the operations shown.

[0109] At 305, user equipment 115-b can communicate with base station 105-b via a communication link. This communication link may include one or more beams of user equipment 115-b associated with the serving cell and one or more beams of base station 105-b.

[0110] At 310, user equipment 115-b can identify a beam fault in the communication link between user equipment 115-b and the serving cell (e.g., SCell) of base station 105-b. For example, parameters associated with the beam of the communication link (e.g., RSRP, RSRQ, SINR, etc. for the connection beam measured by user equipment 115-b) may be below a threshold.

[0111] In 315, user equipment 115-b can determine, based on the identified beam fault, the establishment of the communication link between user equipment 115-b and the serving cell (e.g., a new communication link, rebuilding an old communication link, etc.).

[0112] At 320, user equipment 115-b can select a first beam (e.g., a preferred beam) from the candidate beam set of the serving cell to establish the communication link. In some cases, user equipment 115-b can subsequently initiate a request for uplink resources (e.g., a scheduling request) to send an indication of the selected first beam to the base station. Additionally, in some cases, the request may include a RACH message of the RACH procedure to establish a communication link between the serving cell of user equipment 115-b and base station 105-b.

[0113] At 325, User Equipment 115-b can acquire uplink resources for use in transmitting the indication of the first beam. In some cases, User Equipment 115-b can compare the number of time slots with the number of time slots between the current time and the uplink resource, and determine the availability of the uplink resource based on the fact that the number of time slots between the current time and the uplink resource is less than the number of time slots with the threshold.

[0114] Additionally or alternatively, User Equipment 115-b may send a request (e.g., a scheduling request) based on determined availability, indicating that the number of time slots between the current time and the uplink resource is greater than a time slot threshold. Therefore, User Equipment 115-b may receive an indication of the uplink resource in response to the sent request and may transmit an indication of the selected first beam in the MAC CE on the indicated uplink resource. In some cases, User Equipment 115-b may receive a configuration for beam fault recovery and send a request for the uplink resource based on the received configuration, wherein the received configuration for beam fault recovery includes a sequence of user equipment-specific symbols. Additionally or alternatively, User Equipment 115-b may send a scheduling request sequence indicating the request to Base Station 105-b, wherein the scheduling request sequence is transmitted on the uplink resource corresponding to the highest priority logical channel configured for the user equipment. In some cases, User Equipment 115-b may perform a RACH procedure to request the uplink resource for transmitting the indication of the selected first beam.

[0115] When User Equipment 115-b initiates a request for uplink resources to transmit an indication of a selected first beam, as described above in 320, User Equipment 115-b may perform subsequent actions based on initiating the request. For example, in 325-a, User Equipment 115-b may first identify the uplink control resources used to transmit the request. In some cases, the uplink control resources may include uplink control resources for transmission occasions (e.g., TTI, time slot, subframe, etc.) where User Equipment 115-b may transmit the request. Furthermore, User Equipment 115-b may determine and select the uplink control resource used to transmit the request to indicate which serving cell and / or uplink resources User Equipment 115-b wants to transmit the indication of the selected first beam. For example, the index of the transmission occasion within the set of transmission occasions used to transmit the request may indicate a serving cell where a beam failure has occurred. Furthermore, the index may indicate permission for Base Station 105-b not to transmit uplink resources on that serving cell / beam. This transmission timing relationship with serving cells can be considered a one-to-one mapping. Additionally or alternatively, the index of the transmission timing within the set of transmission timings used to send the request can indicate a set of serving cells on which the beam is not faulty and / or on which the requested uplink resources should be allocated. This transmission timing relationship with multiple serving cells can be considered a many-to-one mapping.

[0116] In 325-b, user equipment 115-b may send the request on uplink control resources, indicating to base station 105-b the failed beam of the serving cell. In some cases, the request may include configuration of uplink control resources associated with beam failure recovery procedures, and user equipment 115-b may send the request on dedicated uplink control resources configured to indicate to base station 105-b the failed beam or set of beams configured for the first serving cell. Additionally or alternatively, as described above, user equipment 115-b may send the request on uplink control resources in a transmission context, wherein the uplink control resources indicate to base station 105-b the failed beam of the serving cell, and the transmission context of the uplink control resources associated with the set of serving cells may indicate the serving cell on which the beam has failed (e.g., based on the one-to-one mapping, many-to-one mapping, etc.).

[0117] In 325-c, user equipment 115-b may, in response to a sent request, receive an indication of uplink resources in a second serving cell from base station 105-b for use by user equipment 115-b to transmit an indication of the selected first beam. In some cases, in response to a sent request, user equipment 115-b may receive a DCI indicating the uplink resources of the second serving cell from base station 105-b for use by user equipment 115-b to transmit an indication of the selected first beam. For example, the second serving cell may include user equipment 115-b's PCell, PSCell, or SpCell (e.g., a special serving cell). Additionally or alternatively, user equipment 115-b may, in response to a sent request, receive an indication of uplink resources in a second serving cell different from the serving cell with beam failure from the base station for use by user equipment 115-b to transmit an indication of the selected first beam.

[0118] At 330, based on a comparison of the timing of the uplink resource availability with a threshold (e.g., the number of time slot thresholds), user equipment 115-b may send an indication of the selected first beam to base station 105-b on the uplink resource, in the MAC CE. In some cases, user equipment 115-b may receive a configuration indicating the threshold from base station 105-b (e.g., via RRC signaling). Furthermore, user equipment 115-b may perform a logical channel prioritization process for the MAC PDU including the MAC CE, wherein the logical channel prioritization process provides the MAC CE with a priority greater than each other MAC CE of the MAC PDU, greater than the data of the MAC PDU, and less than the information of the CCCH message of the MAC PDU. In some cases, user equipment 115-b may send an indication of the selected first beam in the MAC CE based on a determined availability of the uplink resource, indicating that the number of time slots between the current time and the uplink resource is less than the number of time slot thresholds.

[0119] In some cases, user equipment 115-b can identify a beam fault in the second communication link between user equipment 115-b and a second serving cell, including PCell, PSCell, or SpCell. Therefore, user equipment 115-b can initiate a RACH procedure to re-establish the second communication link with the second serving cell, wherein, after the RACH procedure for re-establishing the second communication link with the second serving cell is completed, an indication of the selected first beam is sent. In some cases, the beam fault of the second communication link can be identified before the beam fault occurs. Alternatively, the beam fault of the second communication link can be identified after the beam fault occurs. However, in both cases, as described above, user equipment 115-b can send an indication of the selected first beam after the RACH procedure for re-establishing the second communication link with the second serving cell is completed.

[0120] Furthermore, in some cases, user equipment 115-b can start a timer and counter based on determining that the communication link has been established. Subsequently, user equipment 115-b can increment the counter based on an indication to transmit a selected first beam, and can retransmit the indication for the selected first beam in the MAC CE based on the timer expiring before a message is received on the selected first beam (e.g., from base station 105-b) and the counter falling below a counter threshold. Additionally, when the counter threshold is reached or exceeded, user equipment 115-b can trigger a radio link failure based on the counter meeting the threshold.

[0121] Figure 4An example of a processing flow 400 supporting a beam index indication MAC procedure according to various aspects of this disclosure is shown. In some examples, processing flow 400 may implement various aspects of wireless communication systems 100 and / or 200. Processing flow 400 may include base station 105-c and user equipment 115-c, which may be examples of corresponding base station 105 and user equipment 115, as referenced above. Figures 1 to 3 As described herein, base station 105-c and user equipment 115-c can communicate with each other using beamforming technology. Processing flow 400 may include steps similar to those for selecting a beam and transmitting an indication of the selected beam, as referenced above. Figure 3 However, user equipment 115-c can select the beam and indicate the selected beam for the RACH procedure (e.g., a four-step RACH procedure) rather than the beam failure recovery procedure.

[0122] In the following description of this processing flow 400, operations between user equipment 115-c and base station 105-c may be transmitted in a different order than those shown, or operations performed by base station 105-c and user equipment 115-c may be performed in a different order or at different times. Some operations may also be excluded from this processing flow 400, or other operations may be added to it. It should be understood that although base station 105-c and user equipment 115-c are shown performing multiple operations of processing flow 400, any wireless device can perform the operations shown.

[0123] At 405, User Equipment 115-c can determine the communication link to be established between User Equipment 115-c and the serving cell of Base Station 105-c. For example, User Equipment 115-c may have entered the geographic coverage area of ​​Base Station 105-c and determined to establish an initial communication link with Base Station 105-c via a four-step RACH procedure. Additionally or alternatively, User Equipment 115-c may experience a beam fault in the serving cell, and User Equipment 115-c can perform the four-step RACH procedure to rebuild the communication link with the serving cell instead of performing beam fault recovery. In some cases, depending on whether the serving cell is a PCell, PSCell, or SPCell, User Equipment 115-c can perform the four-step RACH procedure instead of the beam fault recovery procedure, where a beam fault in the PCell, PSCell, or SPCell necessitates the establishment of a new communication link.

[0124] At 410, user equipment 115-c may send the RACH preamble (e.g., the first message) of the four-step RACH procedure. Subsequently, at 415, user equipment 115-c may receive the random access response (e.g., the second message) of the four-step RACH procedure.

[0125] At 420, user equipment 115-c can select a first beam (e.g., a preferred beam) from the candidate beam set of the serving cell. In some cases, user equipment 115-c can select the first beam based on information received in the random access response. Additionally or alternatively, user equipment 115-c can receive the random access response from multiple beams transmitted by base station 105-c (e.g., via beam scanning operation to improve the reliability of successful reception of the random access response at user equipment 115-c, etc.), and can measure the signal quality of the multiple beams to select the first beam.

[0126] At 425, user equipment 115-c can determine the beam from which an indication of a selected first beam is transmitted to base station 105-c. In some cases, user equipment 115-c can determine that a second beam in the candidate beam set is available to transmit an indication of the selected first beam at least before the availability of uplink resources, where the uplink resources include the first beam. Additionally or alternatively, user equipment 115-c can measure signal quality parameters (e.g., RSRP, RSRQ, SINR, or other quality parameters of the beam) of the candidate beam set for the serving cell, including the first beam and the second beam, and can determine that the second beam is superior to the first beam based on the measured signal quality parameters of the first beam and the second beam.

[0127] At 430, user equipment 115-c may send an indication of the selected first beam (e.g., preferred beam) to base station 105-c in the random access message of the four-step RACH procedure, in the MAC CE. For example, the indication of the selected first beam may be sent on the second beam in the connection request message (e.g., message 3) of the four-step RACH procedure.

[0128] At 435, user equipment 115-c can receive a contention resolution message (e.g., message 4) for the four-step RACH procedure from base station 105-c, and base station 105-c can complete the four-step RACH procedure. In some cases, base station 105-c can transmit the contention resolution message on the first beam selected by user equipment 115-c as indicated in the connection request message.

[0129] Figure 5 An example of a processing flow 500 supporting a beam index indication MAC procedure according to various aspects of this disclosure is shown. In some examples, processing flow 500 may implement various aspects of wireless communication systems 100 and / or 200. Processing flow 500 may include base station 105-d and user equipment 115-d, which may be examples of corresponding base station 105 and user equipment 115, as referenced above. Figures 1 to 4As described herein, base station 105-d and user equipment 115-d can communicate with each other using beamforming technology. Processing flow 500 may include similar steps for selecting a beam and sending an indication of the selected beam, as referenced above. Figure 3 and Figure 4 However, unlike process flow 300 but similar to process flow 400, user equipment 115-d can select the beam and instruct the selected beam for a RACH process (e.g., a two-step RACH process) rather than a beam failure recovery process.

[0130] In the following description of the processing flow 500, operations between user equipment 115-d and base station 105-d may be transmitted in a different order than those shown, or operations performed by base station 105-d and user equipment 115-d may be executed in a different order or at different times. Some operations may also be excluded from the processing flow 500, or other operations may be added to the processing flow 500. It should be understood that although base station 105-d and user equipment 115-d are shown performing multiple operations of processing flow 500, any wireless device can perform the operations shown.

[0131] In step 505, similar to process 400, user equipment 115-d can determine the communication link to be established between user equipment 115-d and the serving cell of base station 105-d. However, user equipment 115-d can be configured and is able to perform a two-step RACH procedure instead of a four-step RACH procedure.

[0132] Therefore, at 510, user equipment 115-d can select a first beam from the set of candidate beams of the serving cell. In some cases, user equipment 115-d may make this selection based on a previous signal quality measurement of the candidate beam or an ongoing signal quality measurement of the candidate beam. The signal quality measurement may include one or more of the candidate beam's RSRP, RSRQ, SINR, or other signal quality measurements.

[0133] In 515, User Equipment 115-d can be similar to the reference above. Figure 4 The described technique (e.g., based on signal quality parameter measurements, etc., the second beam is available before the indicated uplink resources are available) determines the beam from which the indication of the selected first beam is transmitted. For example, user equipment 115-d may determine to use the second beam to transmit the indication of the selected first beam.

[0134] In 520, user equipment 115-d may send an indication of the selected first beam on the second beam in the first message (e.g., MsgA) of a two-step RACH procedure, instead of sending the indication of the selected first beam in the connection request message of a four-step RACH procedure.

[0135] At 525, user equipment 115-d can receive the second message (e.g., MsgB) of the two-step RACH procedure from base station 105-d. In some cases, in the first message of the two-step RACH procedure, base station 105-d may use the selected first beam indicated by user equipment 115-d to transmit the second message of the two-step RACH procedure.

[0136] Figure 6 A block diagram 600 of a device 605 supporting a beam indexing MAC process according to various aspects of this disclosure is shown. Device 605 may be an example of various aspects of user equipment 115 as described herein. Device 605 may include a receiver 610, a communication manager 615, and a transmitter 620. Device 605 may also include one or more processors, memory coupled to the one or more processors, and instructions stored in the memory executable by the one or more processors to enable the one or more processors to perform the beam indexing process discussed herein. Each of these components may communicate with each other (e.g., via one or more buses).

[0137] The receiver 610 can receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to media access control procedures indicated by beam indexing). This information can be transmitted to other components of the device 605. The receiver 610 can be a reference. Figure 9 Examples of various aspects of the transceiver 920 are described. The receiver 610 can utilize a single antenna or a set of antennas.

[0138] The communication manager 615 can determine the communication link established between the user equipment and the serving cell of the base station. In some cases, the communication manager 615 can select a first beam from the candidate beam set of the serving cell for the user equipment to establish the communication link. Furthermore, the communication manager 615 can, based on a timing comparison of the availability of the uplink resources with a threshold, send an indication of the selected first beam to the base station on the uplink resources in the MAC control element. The communication manager 615 can be an example of various aspects of the communication manager 910 described herein.

[0139] The communication manager 615 can be implemented as an integrated circuit or chipset of the device 605, and the receiver 610 and the transmitter 620 can be implemented as analog components (e.g., amplifiers, filters, antennas) coupled to the device 605 to enable wireless transmission and reception. The actions performed by the communication manager 615 described herein can be performed to achieve one or more potential advantages. At least one implementation enables the communication manager 615 to establish a communication link with a base station using a preferred beam. Based on this establishment, one or more processors of the device 605 (e.g., processors controlling or associated with the communication manager 615) can facilitate improved spectral efficiency, higher data rates, and in some examples, enhanced efficiency for high reliability and low latency operation, among other benefits.

[0140] The communication manager 615 or its sub-components may be implemented in hardware, processor-executable code (e.g., software or firmware), or any combination thereof. If implemented in processor-executable code, the functionality of the communication manager 615 or its sub-components may be performed by a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described in this disclosure.

[0141] The communication manager 615 or its sub-components may be physically located in different locations, including being distributed such that some functions are implemented by one or more physical components in different physical locations. In some examples, according to various aspects of this disclosure, the communication manager 615 or its sub-components may be separate and distinct components. In some examples, according to various aspects of this disclosure, the communication manager 615 or its sub-components may be combined with one or more other hardware components, including but not limited to input / output (I / O) components, transceivers, network servers, another computing device, one or more other components described in this disclosure, or combinations thereof.

[0142] The transmitter 620 can transmit signals generated by other components of the device 605. In some examples, the transmitter 620 can be co-located with the receiver 610 in a transceiver module. For example, the transmitter 620 can be a reference. Figure 9 Examples of various aspects of the transceiver 920 are described. The transmitter 620 can utilize a single antenna or a set of antennas.

[0143] Figure 7A block diagram 700 illustrates a device 705 supporting a MAC process for beam index indication according to various aspects of this disclosure. The device 705 may be an example of device 605 or aspects of user equipment 115 as described herein. The device 705 may include a receiver 710, a communication manager 715, and a transmitter 735. The device 705 may also include a processor. Each of these components may communicate with each other (e.g., via one or more buses).

[0144] The receiver 710 can receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to the MAC procedure for beam index indication). This information can be transmitted to other components of the device 705. The receiver 710 can be a reference. Figure 9 Examples of various aspects of the transceiver 920 are described. The receiver 710 can utilize a single antenna or a set of antennas.

[0145] The communication manager 715 may be an example of aspects of the communication manager 615 described herein. The communication manager 715 may include a link establishment component 720, a beam selector 725, and a selected beam indicator 730. The communication manager 715 may be an example of aspects of the communication manager 910 described herein.

[0146] The link establishment component 720 can determine the communication link established between the user equipment and the serving cell of the base station.

[0147] The beam selector 725 can select the first beam from the candidate beam set of the serving cell to establish the communication link by the user equipment.

[0148] The selected beam indicator 730 can send an indication of the selected first beam to the base station in the MAC CE on the uplink resource based on a timing comparison of the availability of the uplink resource with a threshold.

[0149] The transmitter 735 can transmit signals generated by other components of the device 705. In some examples, the transmitter 735 can be co-located with the receiver 710 in a transceiver module. For example, the transmitter 735 can be a reference. Figure 9 Examples of various aspects of the transceiver 920 are described. The transmitter 735 can utilize a single antenna or a set of antennas.

[0150] In some cases, the link establishment component 720, beam selector 725, and selected beam indicator 730 may each be, or at least part of, a processor (e.g., a transceiver processor, a radio processor, a transmitter processor, or a receiver processor). The processor may be coupled to a memory and execute instructions stored in that memory that enable the processor to perform or facilitate the features of the link establishment component 720, beam selector 725, and selected beam indicator 730 discussed herein. The transceiver processor may be co-located and / or communicate with (e.g., instructing its operation) the transceiver of the device. The radio processor may be co-located and / or communicate with (e.g., instructing its operation) the radio of the device (e.g., NR radio, LTE radio, Wi-Fi radio). The transmitter processor may be co-located and / or communicate with (e.g., instructing its operation) the transmitter of the device. The receiver processor may be co-located and / or communicate with (e.g., instructing its operation) the receiver of the device.

[0151] Figure 8 A block diagram 800 of a communication manager 805 supporting a beam index indication MAC process according to various aspects of this disclosure is shown. The communication manager 805 may be an example of aspects of the communication manager 615, communication manager 715, or communication manager 910 described herein. The communication manager 805 may include a link establishment component 810, a beam selector 815, a selected beam indicator 820, a beam fault identifier 825, an uplink resource availability component 830, an uplink resource request component 835, a RACH selected beam indicator 840, a prioritization component 845, and a beam indication transmission counter 850. Each of these modules may communicate directly or indirectly with each other (e.g., via one or more buses).

[0152] The link establishment component 810 can determine the communication link established between the user equipment and the serving cell of the base station.

[0153] The beam selector 815 can select a first beam from the candidate beam set of the serving cell for the user equipment to establish the communication link. In some cases, the beam selector 815 can initiate a request for uplink resources to send an indication of the selected first beam to the base station. In some examples, the user equipment can send the request on uplink control resources, indicating a faulty beam of the serving cell to the base station, and in response to the sent request, receive an indication of uplink resources in a second serving cell from the base station for the user equipment to use in sending the indication of the selected first beam.

[0154] The selected beam indicator 820 can, based on a timing comparison of the availability of the uplink resource with a threshold, send an indication of the selected first beam to the base station on the uplink resource, in the MAC CE. In some examples, the selected beam indicator 820 can receive a configuration indicating the threshold from the base station.

[0155] The beam fault identifier 825 can communicate with the base station via the communication link and can identify beam faults in the communication link between the user equipment and the serving cell. Therefore, the beam fault identifier 825 can determine the communication link established between the user equipment and the serving cell based on the identified beam faults.

[0156] The uplink resource availability component 830 can obtain the uplink resource for the user equipment to transmit an indication of the first beam, compare a time slot threshold number with the number of time slots between the current time and the uplink resource, wherein the threshold includes the time slot threshold number, and determine the availability of the uplink resource based on the fact that the number of time slots between the current time and the uplink resource is less than the time slot threshold number. In some examples, the uplink resource availability component 830 can transmit an indication of the selected first beam in the MAC CE based on the determined availability, wherein the determined availability indicates that the number of time slots between the current time and the uplink resource is less than the time slot threshold number. Optionally, the uplink resource availability component 830 can send a request for uplink resource to the base station based on the determined availability, wherein the availability indicates that the number of time slots between the current time and the uplink resource is greater than the time slot threshold number. Therefore, the uplink resource availability component 830 can receive an indication of the uplink resource in response to the sent request, and can send an indication of the selected first beam in the MAC CE on the indicated uplink resource.

[0157] The uplink resource request component 835 can receive a configuration for beam fault recovery, and the request for the uplink resource is sent based on the received configuration. In some cases, the received configuration for beam fault recovery may include a sequence of symbols specific to the user equipment. Additionally or alternatively, the uplink resource request component 835 can send a scheduling request sequence indicating the request to the base station. In some cases, the scheduling request sequence may be sent on uplink resources corresponding to the highest priority logical channel configured for the user equipment.

[0158] In some cases, the uplink resource request component 835 may send the request on uplink control resources, indicating to the base station a failed beam in the serving cell, and may receive, in response to the sent request, an indication of uplink resources in a second serving cell from the base station for the user equipment to use to send an indication of the selected first beam. Additionally or alternatively, the request may include configuration of uplink control resources associated with a beam failure recovery process, and the uplink resource request component 835 may send the request on dedicated uplink control resources configured to indicate to the base station a beam or beam set configured for the failed first serving cell, and may subsequently receive, in response to the sent request, a DCI from the base station's second serving cell, indicating uplink resources in the second serving cell for the user equipment to use to send an indication of the selected first beam. In some cases, the second serving cell may include the user equipment's PCell, PSCell, or SpCell.

[0159] Additionally or alternatively, the uplink resource request component 835 may send the request on uplink control resources during transmission, which instructs the base station that the serving cell's beam has failed and the timing of transmission of uplink control resources associated with the serving cell set, indicating the serving cell with the failed beam. In some cases, the index of the transmission timing within the transmission timing set may indicate the serving cell with the failed beam. Alternatively, the index of the transmission timing within the transmission timing set may indicate the set of serving cells with no failed beam, the set of serving cells that should be allocated the requested uplink resources, or a combination thereof.

[0160] The RACH selected beam indicator 840 can send the MAC control element in the RACH (e.g., random access) message of the RACH procedure to the base station. In some examples, the RACH selected beam indicator 840 can determine that a second beam in the candidate beam set is available to transmit an indication of the first beam, where the uplink resource includes the first beam, at least a threshold earlier than the availability of the uplink resource, and based on the determination that the second beam is available, transmit an indication of the selected first beam in the MAC CE on the second beam. Additionally or alternatively, the RACH selected beam indicator 840 can measure the signal quality parameters of the candidate beam set (including the first and second beams) of the serving cell, determine that the second beam is superior to the first beam based on the measured signal quality parameters of the first and second beams, and transmit an indication of the second beam in the signal of the RACH procedure based on the determination that the second beam is preferred. In some cases, an indication of the selected first beam can be sent on the second beam in the first message (e.g., MsgA) of a two-step RACH procedure. Additionally or alternatively, an indication of the selected first beam can be sent on the second beam in the connection request message (e.g., message 3) of a four-step RACH procedure.

[0161] In some cases, the RACH selected beam indicator 840 can identify a beam failure in the second communication link between the user equipment and the second serving cell, where the second serving cell may include PCell, PSCell, or SpCell. Subsequently, the RACH selected beam indicator 840 can initiate a RACH procedure to rebuild the second communication link with the second serving cell, wherein after the RACH procedure to rebuild the second communication link with the second serving cell is completed, an indication of the selected first beam is sent. In some cases, the beam failure in the second communication link can be identified before the beam failure occurs. Alternatively, the beam failure in the second communication link can be identified after the beam failure occurs.

[0162] The prioritization component 845 can perform a logical channel prioritization process for the MAC PDU including the MAC CE, wherein the logical channel prioritization process provides the MAC CE with information that has a priority greater than that of each other MAC CE of the MAC PDU, greater than the data of the MAC PDU, and less than the CCCH message of the MAC PDU.

[0163] The beam indication transmit counter 850 can start a timer and counter based on determining that the communication link has been established, and can increment the counter based on the indication of transmitting the selected first beam. Additionally, the beam indication transmit counter 850 can retransmit the indication of the selected first beam in the MAC CE based on the timer expiring before a message is received on the selected first beam and the counter falling below a counter threshold. In some cases, the beam indication transmit counter 850 can trigger a radio link failure based on the counter meeting a counter threshold.

[0164] In some cases, the link establishment component 810, beam selector 815, selected beam indicator 820, beam fault identifier 825, uplink resource availability component 830, uplink resource request component 835, RACH selected beam indicator 840, priority component 845, and beam indication transmit counter 850 may each be, or at least, part of a processor (e.g., a transceiver processor, a radio processor, a transmitter processor, or a receiver processor). The processor may be coupled to a memory and execute instructions stored in that memory that enable the processor to perform or facilitate the features of the link establishment component 810, beam selector 815, selected beam indicator 820, beam fault identifier 825, uplink resource availability component 830, uplink resource request component 835, RACH selected beam indicator 840, priority component 845, and beam indication transmit counter 850 discussed herein.

[0165] Figure 9 A schematic diagram of a system 900 including a device 905 supporting a beam index indication MAC process is shown according to various aspects of this disclosure. The device 905 may be an example of the device 605, device 705, or user equipment 115 described herein, or include components thereof. The device 905 may include components for bidirectional voice and data communication, including components for transmitting and receiving communications, including a communication manager 910, an I / O controller 915, a transceiver 920, an antenna 925, a memory 930, and a processor 940. These components may communicate electronically via one or more buses (e.g., bus 945).

[0166] The communication manager 910 can determine the communication link to be established between the user equipment and the serving cell of the base station. In some cases, the communication manager 910 can select a first beam from the candidate beam set of the serving cell for the user equipment to establish the communication link. Alternatively, the communication manager 910 can, based on a timing comparison of uplink resource availability with a threshold, send an indication of the selected first beam to the base station on the uplink resources in the MAC CE. At least one implementation enables the communication manager 910 to establish a communication link with the base station using a preferred beam. Based on implementation, one or more processors of the device 905 (e.g., processors controlling or associated with the communication manager 910) can facilitate improved spectral efficiency, higher data rates, and in some examples, enhanced efficiency for high-reliability and low-latency operation, among other benefits.

[0167] The I / O controller 915 manages the input and output signals of the device 905. The I / O controller 915 can also manage peripheral devices not integrated into the device 905. In some cases, the I / O controller 915 may represent a physical connection or port to an external peripheral device. In some cases, the I / O controller 915 may utilize an operating system such as iOS®, Android®, MS-DOS®, MS-WINDOWS®, OS / 2®, UNIX®, LINUX®, or other known operating systems. In other cases, the I / O controller 915 may represent or interact with a modem, keyboard, mouse, touchscreen, or similar device. In some cases, the I / O controller 915 may be implemented as part of a processor. In some cases, a user may interact with the device 905 via the I / O controller 915 or via hardware components controlled by the I / O controller 915.

[0168] As described above, the transceiver 920 can communicate bidirectionally via one or more antennas, wired or wireless links. For example, the transceiver 920 can represent a wireless transceiver and can communicate bidirectionally with another wireless transceiver. The transceiver 920 may also include a modem to modulate the packets and provide the modulated packets to the antenna for transmission, and to demodulate the packets received from the antenna.

[0169] In some cases, the wireless device may include a single antenna 925. However, in other cases, the device may have more than one antenna 925, which is capable of transmitting or receiving multiple wireless transmissions simultaneously.

[0170] The memory 930 may include random access memory (RAM) and read-only memory (ROM). The memory 930 may store computer-readable, computer-executable code 935, including instructions that, when executed, cause the processor to perform the various functions described herein. In some cases, the memory 930 may contain a basic I / O system (BIOS), which controls basic hardware or software operations, such as interaction with peripheral components or devices.

[0171] The processor 940 may include intelligent hardware devices (e.g., general-purpose processors, DSPs, central processing units (CPUs), microcontrollers, ASICs, FPGAs, programmable logic devices, discrete gate or transistor logic components, discrete hardware components, or any combination thereof). In some cases, the processor 940 may be configured to use a memory controller to operate a memory array. In other cases, the memory controller may be integrated into the processor 940. The processor 940 may be configured to execute computer-readable instructions stored in memory (e.g., the memory 930) to cause the device 905 to perform various functions (e.g., functions or tasks supporting beam index-indicated MAC procedures).

[0172] The code 935 may include instructions for implementing various aspects of this disclosure, including instructions for supporting wireless communication. The code 935 may be stored in a non-transitory computer-readable medium, such as system memory or other types of memory. In some cases, the code 935 may not be directly executable by the processor 940, but may enable a computer (e.g., when compiled and executed) to perform the functions described herein.

[0173] Figure 10 A flowchart illustrating a method 1000 for a MAC procedure supporting beam index indication according to various aspects of this disclosure is shown. As described herein, operation of method 1000 can be implemented by user equipment 115 or its components. For example, operation of method 1000 can be implemented by reference to... Figures 6 to 9 The communication manager described herein is used for execution. In some examples, the user equipment may execute a set of instructions to control the functional elements of the user equipment to perform the functions described below. Additionally or alternatively, the user equipment may use dedicated hardware to perform various aspects of the functions described below.

[0174] At 1005, the user equipment can determine the communication link established between the user equipment and the serving cell of the base station. The operation of 1005 can be performed according to the methods described herein. In some examples, aspects of the operation of 1005 can be derived from references... Figures 6 to 9 The described link establishment component is used to perform this.

[0175] In step 1010, the user equipment can select the first beam from the candidate beam set of the serving cell to establish the communication link. The operation of step 1010 can be performed according to the method described herein. In some examples, aspects of operation 1010 can be found in references... Figures 6 to 9 The described beam selector is used to perform this action.

[0176] In step 1015, based on a timing comparison of uplink resource availability with a threshold, the user equipment can, on the uplink resources, in the MAC CE, send an indication of the selected first beam to the base station. The operation of step 1015 can be performed according to the method described herein. In some examples, such as references... Figures 6 to 9 The operation of 1015 can be performed by the selected beam indicator.

[0177] Figure 11 A flowchart illustrating a method 1100 for a MAC procedure supporting beam index indication according to various aspects of this disclosure is shown. As described herein, operation of method 1100 can be implemented by user equipment 115 or its components. For example, operation of method 1100 can be implemented by reference to... Figures 6 to 9 The communication manager described herein is used for execution. In some examples, the user equipment may execute a set of instructions to control the functional elements of the user equipment to perform the functions described below. Additionally or alternatively, the user equipment may use dedicated hardware to perform various aspects of the functions described below.

[0178] At 1105, the user equipment can communicate with the base station via this communication link. The operation of 1105 can be performed according to the methods described herein. In some examples, such as reference... Figures 6 to 9 The operation of 1105 can be performed by the beam fault identifier.

[0179] In 1110, the user equipment can identify beam faults in the communication link between the user equipment and the serving cell. The operation of 1110 can be performed according to the methods described herein. In some examples, such as reference... Figures 6 to 9 The operation of 1110 can be performed by the beam fault identifier.

[0180] At 1115, the user equipment can determine the communication link established between the user equipment and the serving cell of the base station. The operation of 1115 can be performed according to the methods described herein. In some examples, aspects of the operation of 1115 can be derived from references... Figures 6 to 9 The described link establishment component is used to perform this.

[0181] At 1120, the user equipment can determine the communication link established between the user equipment and the serving cell based on the identified beam fault. The operation of 1120 can be performed according to the methods described herein. In some examples, aspects of the operation of 1120 can be derived from references... Figures 6 to 9 The described beam fault identifier is used to perform this action.

[0182] At 1125, the user equipment can select the first beam from the candidate beam set of the serving cell to establish the communication link. The operation of 1125 can be performed according to the method described herein. In some examples, aspects of the operation of 1125 can be found in references... Figures 6 to 9 The described beam selector is used to perform this action.

[0183] At 1130, based on a timing comparison of uplink resource availability with a threshold, the user equipment can, on the uplink resources, in the MAC CE, send an indication of the selected first beam to the base station. The operation of 1130 can be performed according to the method described herein. In some examples, aspects of the operation of 1130 can be referenced... Figures 6 to 9 The selected beam indicator is described to perform this action.

[0184] Figure 12 A flowchart illustrating a method 1200 for a MAC procedure supporting beam index indication according to various aspects of this disclosure is shown. As described herein, operation of method 1200 can be implemented by user equipment 115 or its components. For example, operation of method 1200 can be implemented by reference to... Figures 6 to 9 The communication manager described herein is used for execution. In some examples, the user equipment may execute a set of instructions to control the functional elements of the user equipment to perform the functions described below. Additionally or alternatively, the user equipment may use dedicated hardware to perform various aspects of the functions described below.

[0185] At 1205, the user equipment can determine the communication link established between the user equipment and the serving cell of the base station. The operation of 1205 can be performed according to the methods described herein. In some examples, aspects of the operation of 1205 can be derived from references... Figures 6 to 9 The described link establishment component is used to perform this.

[0186] At 1210, the user equipment can select the first beam from the candidate beam set of the serving cell to establish the communication link. The operation of 1210 can be performed according to the methods described herein. In some examples, aspects of the operation of 1210 can be derived from references... Figures 6 to 9 The described beam selector is used to perform this action.

[0187] In step 1215, based on a timing comparison of uplink resource availability with a threshold, the user equipment can, on the uplink resources, in the MAC CE, send an indication of the selected first beam to the base station. The operation of step 1215 can be performed according to the method described herein. In some examples, aspects of the operation of step 1215 can be referenced... Figures 6 to 9 The selected beam indicator is described to perform this action.

[0188] At 1220, the user equipment may send the MAC CE to the base station in the RACH message of the RACH procedure. The operation of 1220 can be performed according to the method described herein. In some examples, aspects of operation 1220 can be found in references... Figures 6 to 9 The described RACH is performed by the selected beam indicator.

[0189] It should be noted that the methods described herein describe possible implementations, and the operations and steps can be rearranged or otherwise modified, and other implementations are possible. Furthermore, aspects from two or more methods can be combined.

[0190] The technologies described herein can be used in various wireless communication systems, such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier Frequency Division Multiple Access (SC-FDMA), and other systems. CDMA systems can implement radio technologies such as CDMA2000, Universal Terrestrial Radio Access (UTRA), etc. CDMA2000 encompasses the IS-2000, IS-95, and IS-856 standards. Versions of IS-2000 are commonly referred to as CDMA2000 1X, 1X, etc. IS-856 (TIA-856) is commonly referred to as CDMA2000 1xEV-DO, High-Speed ​​Packet Data (HRPD), etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. TDMA systems can implement radio technologies such as Global System for Mobile Communications (GSM).

[0191] OFDMA systems can implement radio technologies such as Ultra Mobile Broadband (UMB), Evolved UTRA (UTRA), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM, etc. UTRA and E-UTRA are part of the Universal Mobile Telecommunications System (UMTS). LTE, LTE-A, and LTE-A Pro are UMTS versions using E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, LTE-A Pro, NR, and GSM are described in documents from an organization called the 3rd Generation Partnership Project (3GPP). CDMA2000 and UMB are described in documents from an organization called 3rd Generation Partnership Project 2 (3GPP2). The technologies described herein can be used in the systems and radio technologies mentioned herein, as well as in other systems and radio technologies. While aspects of LTE, LTE-A, LTE-A Pro, or NR systems may be described for illustrative purposes, and the terms LTE, LTE-A, LTE-A Pro, or NR may be used in most of the description, the techniques described herein may be applied beyond LTE, LTE-A, LTE-A Pro, or NR applications.

[0192] Macro cells typically cover a relatively large geographic area (e.g., a radius of several kilometers) and allow unrestricted access to user equipment (UEs) subscribing to services from network providers. In contrast, small cells can be associated with low-power base stations and can operate in the same or different (e.g., licensed, unlicensed, etc.) frequency bands as macro cells. Depending on various examples, small cells can include picocells, femtocells, and microcells. For example, a picocell can cover a small geographic area and allow unrestricted access to UEs subscribing to services from network providers. A femtocell can also cover a small geographic area (e.g., a home) and provide restricted access to UEs associated with that femtocell (e.g., UEs in a Closed Subscriber Group (CSG), UEs of a user in a home, etc.). An eNB for a macro cell can be referred to as a macro eNB. An eNB for a small cell can be referred to as a small cell eNB, pico eNB, femtocell eNB, or home eNB. An eNB can support one or more (e.g., two, three, four, etc.) cells and can also support communication using one or more component carriers.

[0193] The wireless communication system described herein can support synchronous or asynchronous operation. For synchronous operation, the base stations can have similar frame timings, and transmissions from different base stations can be approximately time-aligned. For asynchronous operation, the base stations can have different frame timings, and transmissions from different base stations may be time-inconsistent. The techniques described herein can be used for both synchronous and asynchronous operation.

[0194] The information and signals described herein can be represented using any of a variety of different technologies and processes. For example, data, instructions, commands, information, signals, bits, symbols, and chips referenced throughout the description can be represented by voltage, current, electromagnetic waves, magnetic fields or particles, light fields or particles, or any combination thereof.

[0195] The various illustrative blocks and modules described in this disclosure can be implemented or performed using a general-purpose processor, DSP, ASIC, FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. The general-purpose processor can be a microprocessor, but optionally, it can be any conventional processor, controller, microcontroller, or state machine. The processor can also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, a combination of one or more microprocessors with a DSP core, or any other such configuration).

[0196] The functions described herein can be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, these functions can be stored on or transmitted via a computer-readable medium as one or more instructions or code. Other examples and implementations are within the scope of this disclosure and the appended claims. For example, due to the nature of software, the functions described herein can be implemented using software executed by a processor, hardware, firmware, hardwired, or any combination thereof. Features implementing functions can also be physically located in different locations, including being distributed such that portions of the functionality are implemented in different physical locations.

[0197] Computer-readable media includes non-transitory computer storage media and communication media, encompassing any medium that facilitates the transfer of a computer program from one place to another. A non-transitory storage medium can be any available medium accessible to a general-purpose or special-purpose computer. By way of example, and not limitation, a non-transitory computer-readable medium can include RAM, ROM, electrically erasable programmable ROM (EEPROM), flash memory, optical disc (CD) ROM or other optical disc storage devices, magnetic disk storage devices or other magnetic storage devices, or any other non-transitory medium that can be used to carry or store desired program code components in the form of instructions or data structures, and that can be accessed by a general-purpose or special-purpose computer or a general-purpose or special-purpose processor. Furthermore, any connection is appropriately referred to as a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technology (such as infrared, radio, and microwave), then that coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technology (such as infrared, radio, and microwave) is included in the definition of medium. The discs and platters used here include CDs, laser discs, optical discs, digital multifunction discs (DVDs), floppy disks, and Blu-ray discs, where discs typically reproduce data magnetically, while platters reproduce data optically using lasers. Combinations of these are also included within the scope of computer-readable media.

[0198] As used herein, the word "or" in a list of items (e.g., a list of items beginning with a phrase such as "at least one" or "one or more") signifies an inclusive list, for example, a list having at least A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Furthermore, as used herein, the phrase "based on" should not be construed as referring to a closed set of conditions. For example, an exemplary step described as "based on condition A" may be based on conditions A and B without departing from the scope of this disclosure. In other words, as used herein, the phrase "based on" should be interpreted in the same manner as the phrase "at least partially based on".

[0199] In the accompanying drawings, similar parts or features may have the same reference numerals. Furthermore, various parts of the same type can be distinguished by adding a dash and a second reference numeral after the reference numeral to differentiate between similar parts. If only the first reference numeral is used in the description, the description applies to any similar part having the same first reference numeral, regardless of the second or other subsequent reference numerals.

[0200] The description set forth herein, taken in conjunction with the accompanying drawings, describes an exemplary configuration and does not represent all possible embodiments or all examples within the scope of the claims. The term "exemplary" as used herein means "serving as an example, instance, or illustration," not "preferred" or "superior to other examples." To provide an understanding of the described techniques, the detailed description includes specific details. However, these techniques can be implemented without these specific details. In some cases, well-known structures and devices are shown in block diagram form to avoid obscuring the concept of the examples.

[0201] The description provided herein enables those skilled in the art to make or use this disclosure. Various modifications to this disclosure will be apparent to those skilled in the art, and the general principles defined herein can be applied to other variations without departing from the scope of this disclosure. Therefore, this disclosure is not limited to the examples and designs described herein, but is accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for conducting wireless communication at a user equipment (UE), comprising: Establish a communication link between the UE and the serving cell of the base station, wherein the serving cell includes a subcell; The UE selects the first beam from multiple candidate beams of the serving cell to establish the communication link; The UE sends a scheduling request to the base station based on the beam failure recovery process of the subcell associated with the base station, at least in part based on the unavailability of one or more second uplink resources for transmitting beam index indication, to request one or more first uplink resources, which are available to the UE for use to transmit the beam index indication for a selected first beam to the base station. In response to the scheduling request, an indication of one or more first uplink resources is received, the one or more first uplink resources being used by the UE to transmit the beam index indication; and The UE sends a beam index indication for a selected first beam to the base station in an uplink media access control (MAC) control element on the one or more first uplink resources, based at least in part on an indication of the one or more uplink resources and at least in part on the availability of the one or more uplink resources.

2. The method according to claim 1, further comprising: Send the scheduling request for uplink control resources that indicate to the base station that the serving cell's beam has failed; as well as In response to the scheduling request, the UE receives from the base station an indication of one or more first uplink resources in the second serving cell, the one or more first uplink resources in the second serving cell being used by the UE to transmit a beam index indication for a selected first beam.

3. The method according to claim 1, wherein, The scheduling request includes the configuration of uplink control resources associated with the beam fault recovery process, and wherein: The scheduling request is sent on dedicated uplink control resources, which are configured to indicate to the base station one or more failed beams configured for the serving cell. In response to the scheduling request, and receiving an indication of one or more first uplink resources from the second serving cell of the base station via downlink control information, the downlink control information indicating the one or more first uplink resources of the second serving cell for the UE to use to transmit the beam index indication of the selected first beam.

4. The method according to claim 1, further comprising: The uplink control resource sends a scheduling request for transmission timing, the uplink control resource instructing the base station that the serving cell's beam has failed, and the transmission timing of the uplink control resource is associated with a set of serving cells indicating that the serving cell's beam has failed. as well as In response to the scheduling request, the UE receives from the base station the indication of one or more first uplink resources in a second serving cell different from the serving cell, the one or more first uplink resources in the second serving cell different from the serving cell being used by the UE to transmit the beam index indication of the selected first beam.

5. The method according to claim 1, wherein, The scheduling request includes a random access message for a random access procedure to establish the communication link between the UE and the serving cell of the base station.

6. The method according to claim 1, wherein, Determining the establishment of the communication link includes: Communicate with the base station via the communication link; Identify beam faults in the communication link between the UE and the serving cell; and The establishment of the communication link between the UE and the serving cell is determined, at least in part, based on the identified beam fault.

7. The method according to claim 1, in, Sending the scheduling request also includes: The UE acquires one or more uplink resources, which are used by the UE to send the beam index indication for the first beam. Compare the threshold number of time slots with the number of time slots between the current time and the one or more uplink resources; The availability of the one or more uplink resources is determined at least in part based on the fact that the number of time slots between the current time and the one or more uplink resources is greater than the threshold number of time slots. The scheduling request for the one or more first uplink resources is sent to the base station at least in part based on the determined availability, wherein the determined availability indicates that the number of time slots between the current time and the one or more second uplink resources is greater than a threshold number of time slots; Receiving the instruction further includes: In response to the scheduling request, the indication for the one or more first uplink resources is received, wherein the beam index indication for the selected first beam is sent in the uplink MAC control element based at least in part on the indication for the one or more first uplink resources.

8. The method according to claim 7, further comprising: The configuration for beam fault recovery is received, and the scheduling request for the one or more first uplink resources is sent at least in part based on the received configuration.

9. The method according to claim 7, wherein, Sending the scheduling request for the one or more first uplink resources to the base station includes: Send a scheduling request sequence indicating the scheduling request to the base station.

10. The method according to claim 9, wherein, The scheduling request sequence is sent on the uplink resources corresponding to the highest priority logical channel configured for the UE.

11. The method according to claim 1, wherein, The beam index indication for transmitting the selected first beam includes: The uplink MAC control element is sent to the base station in the random access message of the random access procedure.

12. The method according to claim 1, further comprising: A logical channel prioritization process is performed on the MAC protocol data unit including the uplink MAC control element, wherein the logical channel prioritization process provides the uplink MAC control element with a priority greater than that of each other uplink MAC control element of the MAC protocol data unit, greater than the data of the MAC protocol data unit, and less than the information of the common control channel message of the MAC protocol data unit.

13. The method according to claim 1, further comprising: The timer and counter are started at least in part based on determining that the communication link has been established; The counter is incremented at least in part based on the transmission of the beam index indication for the selected first beam; as well as The beam index indication for the selected first beam is retransmitted in the uplink MAC control element, based at least in part on the timer expiring before a message is received on the selected first beam and the counter falling below a counter threshold.

14. The method according to claim 1, wherein, The beam index indication for the selected first beam is transmitted based at least in part on a timing comparison with a threshold of the availability of the one or more first uplink resources.

15. A user equipment (UE) for wireless communication, comprising: Memory, and One or more processors, coupled to the memory, and configured to enable the user equipment (UE): Establish a communication link between the UE and the serving cell of the base station, wherein the serving cell includes a subcell; The UE selects the first beam from multiple candidate beams of the serving cell to establish the communication link; The UE sends a scheduling request to the base station based on the beam failure recovery process of the subcell associated with the base station, at least in part based on the unavailability of one or more second uplink resources for transmitting beam index indication, to request one or more first uplink resources, which are available to the UE for use to transmit the beam index indication for a selected first beam to the base station. In response to the scheduling request, an indication of one or more first uplink resources is received, the one or more first uplink resources being used by the UE to transmit the beam index indication; and The UE sends a beam index indication for a selected first beam to the base station in an uplink media access control (MAC) control element on the one or more first uplink resources, based at least in part on an indication of the one or more uplink resources and at least in part on the availability of the one or more uplink resources.

16. The UE according to claim 15, wherein, The scheduling request includes the configuration of uplink control resources associated with the beam fault recovery process, and wherein: The scheduling request is sent on dedicated uplink control resources, which are configured to indicate to the base station one or more failed beams configured for the serving cell. In response to the scheduling request, and receiving an indication of one or more first uplink resources from the second serving cell of the base station via downlink control information, the downlink control information indicating the one or more first uplink resources of the second serving cell for the UE to use to transmit the beam index indication of the selected first beam.

17. The UE according to claim 15, wherein, In order to send the scheduling request, the one or more processors are configured to cause the UE to: The UE acquires one or more uplink resources, which are used by the UE to send the beam index indication for the first beam. Compare the threshold number of time slots with the number of time slots between the current time and the one or more uplink resources; The availability of the one or more uplink resources is determined at least in part based on the fact that the number of time slots between the current time and the one or more uplink resources is greater than the threshold number of time slots. The scheduling request for the one or more first uplink resources is sent to the base station, at least in part based on the determined availability, wherein the determined availability indicates that the number of time slots between the current time and the one or more second uplink resources is greater than a threshold number of time slots. In order to receive the instruction, the one or more processors are configured to: In response to the scheduling request, the indication for the one or more first uplink resources is received, wherein the beam index indication for the selected first beam is sent in the uplink MAC control element based at least in part on the indication for the one or more first uplink resources.

18. The UE according to claim 15, wherein, The one or more processors are configured to cause the UE to: A logical channel prioritization process is performed on the MAC protocol data unit including the uplink MAC control element, wherein the logical channel prioritization process provides the uplink MAC control element with a priority greater than that of each other uplink MAC control element of the MAC protocol data unit, greater than the data of the MAC protocol data unit, and less than the information of the common control channel message of the MAC protocol data unit.

19. The UE according to claim 15, wherein, The beam index indication for the selected first beam is transmitted based at least in part on a timing comparison with a threshold of the availability of the one or more first uplink resources.

20. An apparatus for wireless communication at a user equipment (UE), comprising: Components for determining the establishment of a communication link between the UE and the serving cell of the base station, wherein the serving cell includes a subcell; A component for the UE to select the first beam from a plurality of candidate beams of the serving cell to establish the communication link; A component for the UE to send a scheduling request to the base station, at least in part based on the unavailability of one or more second uplink resources for transmitting a beam index indication, according to the beam fault recovery process of the subcell associated with the base station, to request one or more first uplink resources, which are available to the UE for use to transmit the beam index indication for a selected first beam to the base station. A component for receiving an indication of one or more first uplink resources in response to the scheduling request, the one or more first uplink resources being used by the UE to transmit the beam index indication; and A component for transmitting, in an uplink media access control (MAC) control element on one or more first uplink resources, an indication of the beam index of a selected first beam to the base station by the UE, based at least in part on an indication of the availability of the one or more uplink resources.

21. A non-transitory computer-readable medium storing code for wireless communication at a user equipment (UE), the code including instructions executable by one or more processors to: Determine whether to establish a communication link between the UE and the serving cell of the base station, wherein, The service cell includes sub-cells; The UE selects the first beam from multiple candidate beams of the serving cell to establish the communication link; The UE sends a scheduling request to the base station based on the beam failure recovery process of the subcell associated with the base station, at least in part based on the unavailability of one or more second uplink resources for transmitting beam index indication, to request one or more first uplink resources, which are available to the UE for use to transmit the beam index indication for a selected first beam to the base station. In response to the scheduling request, an indication of one or more first uplink resources is received, the one or more first uplink resources being used by the UE to transmit the beam index indication; as well as The UE sends a beam index indication for a selected first beam to the base station in an uplink media access control (MAC) control element on the one or more first uplink resources, based at least in part on an indication of the one or more uplink resources and at least in part on the availability of the one or more uplink resources.

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