Beam failure reporting

This application is a reissue of and claims priority to U.S. Non-Provisional Patent Application Ser. No. 17/051,381, filed on Oct. 28, 2020, which in turn is a National Stage Entry of and claims priority to International Patent Application Serial No. PCT/US2019/037398, filed on Jun. 15, 2019, which in turn claims priority to U.S. Provisional Patent Application Ser. No. 62/687,983, filed on Jun. 21, 2018, the disclosures of which are incorporated by reference herein in their entireties.

The evolution of wireless communication to fifth generation (5G) standards and technologies provides higher data rates and greater capacity, with improved reliability and lower latency, which enhances mobile broadband services. 5G technologies also enables new classes of services for vehicular, fixed wireless broadband, and the Internet of Things (IoT).

A unified air interface, which utilizes licensed, unlicensed, and shared license radio spectrum, in multiple frequency bands, is one aspect of enabling the capabilities of 5G systems. The 5G air interface utilizes radio spectrum in bands below 1 GHz (sub-gigahertz), below 6 GHz (sub-6 GHz), and above 6 GHz. Radio spectrum above 6 GHz includes millimeter wave (mmWave) frequency bands that provide wide channel bandwidths to support higher data rates for wireless broadband.

To increase the capacity of 5G radio networks, Multiple Input Multiple Output (MIMO) antenna systems are used to beamform signals transmitted between base stations and user terminals. In 5G networks, a large number of MIMO antennas (e.g., hundreds of antennas) are employed for beamforming signals, which is often referred to as Massive MIMO, to provide beamformed transmission and reception that is focused on small areas of space around individual user terminals. Massive MIMO beamforming improves network throughput, energy efficiency, and interference rejection. Massive MIMO systems use a channel estimate of the radio frequency (RF) channel characteristics between the base station and the user terminal to determine beamforming coefficients for transmission and reception.

In Fifth Generation New Radio (5G NR) wireless communication systems, if the signal strength or signal quality of a serving downlink transmit beam to a user device (e.g., User Equipment or UE) has poor link quality, a lower layer (e.g., physical layer) in the network stack will send a beam failure instance indication to the Media Access Control (MAC) entity in the UE's network stack. The MAC entity will perform a beam failure detection/recovery procedure. When the beam failure happens, the MAC entity will initiate a random-access procedure. During the random-access procedure, the user equipment will select a downlink transmit beam and select one of the preambles that are associated with the downlink transmit beam. After the random-access procedure is successfully completed, a serving cell base station (e.g., gNB) determines that the user equipment has changed the downlink transmit beam.

The gNB may configure the UE with dedicated preambles or time-frequency resources for the downlink transmit beam. With these resources, the UE does not contend with other UEs to transmit a preamble. This type of random-access procedure is called contention-free random access. Otherwise, a UE has to perform a contention-based random-access procedure where it may take a longer time to complete the random-access procedure.

Because there are limited numbers of preambles and time-frequency resources, in most cases, a UE is not configured with dedicated preambles and time-frequency resources, so contention-based random access is used. Even when the UE is configured with dedicated preambles and time-frequency resources for a downlink transmit beam, the UE still needs to fall back to using the contention-based random-access procedure, if the signal strength or signal quality of the beam has poor link quality.

This summary is provided to introduce simplified concepts of beam failure reporting. The simplified concepts are further described below in the Detailed Description. This summary is not intended to identify essential features of the claimed subject matter, nor is it intended for use in determining the scope of the claimed subject matter.

In aspects, methods, devices, and means for reporting a beam failure by a user equipment in a wireless communication network are described in which the user equipment receives a first uplink grant and initiates a beam recovery procedure. The user equipment, based on the beam recovery procedure determining that a beam has failed, transmits, using the first uplink grant, a first Media Access Control Protocol Data Unit including a first MAC Control Element that indicates a first Synchronization Signal Block and a second Synchronization Signal Block, the transmission being effective to cause the base station to determine that, based on receiving the first Synchronization Signal Block, the beam failure was detected by the user equipment on the first Synchronization Signal Block.

In other aspects, methods, devices, and means for managing a beam failure report from a user equipment by a base station in a wireless communication network are described in which the base station receives, from the user equipment, a first Media Access Control Protocol Data Unit including a first MAC Control Element that indicates a first Synchronization Signal Block and a second Synchronization Signal Block. The base station determines, based on receiving the first Synchronization Signal Block, that the user equipment detected a beam failure on the first Synchronization Signal Block, and the base station selects a first downlink transmit beam with a lighter traffic load among the beams that are associated with the Synchronization Signal Blocks indicated in the first MAC Control Element, the first downlink transmit beam being associated with a first Synchronization Signal Block.

In Fifth Generation New Radio (5G NR) wireless communication systems, if the signal strength or signal quality of a serving-cell downlink transmit beam to a user device (e.g., User Equipment or UE) has poor link quality, a lower layer (e.g., physical layer) in the network stack will send a beam failure instance indication to the Media Access Control (MAC) entity in the UE's network stack. The MAC entity will perform a beam failure detection/recovery procedure. When the beam failure happens, the MAC entity will initiate a random-access procedure. During the random-access procedure, the user equipment will select a downlink transmit beam and select one of the preambles that are associated with the downlink transmit beam. After the random-access procedure is successfully completed, a serving cell base station (e.g., gNB) determines that the user equipment has changed the downlink transmit beam.

The base station may configure the user equipment with dedicated preambles or time-frequency resources for the downlink transmit beam. With these resources, the user equipment does not contend with other UEs to transmit a preamble. This type of random-access procedure is called contention-free random access. Otherwise, a user equipment has to perform a contention-based random-access procedure where it may take a longer time to complete the random-access procedure.

Since there are a limited number of preambles and time-frequency resources, in most cases, a user equipment is not configured with dedicated preambles and time-frequency resources, so contention-based random access is used. Even when the user equipment is configured with dedicated preambles and time-frequency resources for a downlink transmit beam, if the signal strength or signal quality of the beam has poor link quality, the user equipment still needs to fall back to using the contention-based random-access procedure.

In aspects, an approach to reporting a beam failure is described that reduces the amount of time required to perform the beam recovery procedure. The user equipment sends beam failure information to the base station using a configured grant. When a beam failure happens, the UE may not able to receive an uplink grant from the base station, so the user equipment may not be able to transmit beam failure information to the base station. However, if the user equipment has received a configured grant, the user equipment still can use the configured grant to transmit beam failure information to the network.

In an uplink, the base station can dynamically allocate resources to UEs via a Cell Radio Network Temporary Identifier (C-RNTI) on a Physical Downlink Control Channel (PDCCH). A user equipment monitors the PDCCH(s) in order to find possible grants for uplink transmission when its downlink reception is enabled which is activity governed by Discontinuous Reception (DRX) when DRX is configured. When Cell Allocation (CA) is configured, the same C-RNTI applies to all serving cells.

Type 1, in which, Radio Resource Control (RRC) directly provides the configured uplink grant (including periodicity), and Type 2, in which the RRC defines the periodicity of the configured uplink grant while the PDCCH addressed to Configured Scheduling Radio Network Temporary Identity (CS-RNTI) can either signal and activate the configured uplink grant, or deactivate it (e.g., a PDCCH addressed to the CS-RNTI indicates that the uplink grant can be implicitly reused according to the periodicity defined by RRC, until it is deactivated). In addition, with configured grants, the base station can allocate uplink resources for initial Hybrid Automatic Repeat Request (HARQ) transmissions to UEs. Two types of configured uplink grants are defined:

When a configured uplink grant is active, if the user equipment cannot find its C-RNTI or CS-RNTI on the PDCCH(s), the user equipment can make an uplink transmission according to the configured uplink grant. Otherwise, if the user equipment finds its C-RNTI or CS-RNTI on the PDCCH(s), the PDCCH allocation overrides the configured uplink grant. Retransmissions other than repetitions are explicitly allocated via PDCCH(s).

When CA is configured, at most one configured uplink grant can be signaled per serving cell. When Broadcast Control Channel (BCCH) Allocation (BA) is configured, at most one configured uplink grant can be signaled per Bandwidth Part (BWP). On each serving cell, there can be only one configured uplink grant active at a time. A configured uplink grant for one serving cell can either be of Type 1 or Type 2 as described previously. For Type 2, activation and deactivation of configured uplink grants are independent among the serving cells. When a Supplementary Uplink (SUL) is configured, the configured uplink grant can only be signaled for one of the two uplinks of the cell.

1 FIG. 100 110 110 120 121 122 130 130 131 132 110 120 illustrates an example environmentwhich includes a user equipment(UE) that can communicate with base stations(illustrated as base stationsand) through wireless communication links(wireless link), illustrated as wireless linksand. For simplicity, the UEis implemented as a smartphone but may be implemented as any suitable computing or electronic device, such as a mobile communication device, modem, cellular phone, gaming device, navigation device, media device, laptop computer, desktop computer, tablet computer, smart appliance, vehicle-based communication system, or an Internet-of-Things (IoT) device such as a sensor or an actuator. The base stations(e.g., an Evolved Universal Terrestrial Radio Access Network Node B, E-UTRAN Node B, evolved Node B, eNodeB, eNB, Next Generation Node B, gNode B, gNB, or the like) may be implemented in a macrocell, microcell, small cell, picocell, and the like, or any combination thereof.

120 110 131 132 131 132 120 110 110 120 130 130 110 130 120 110 The base stationscommunicate with the user equipmentusing the wireless linksand, which may be implemented as any suitable type of wireless link. The wireless linksandinclude control and data communication, such as downlink of data and control information communicated from the base stationsto the user equipment, uplink of other data and control information communicated from the user equipmentto the base stations, or both. The wireless linksmay include one or more wireless links (e.g., radio links) or bearers implemented using any suitable communication protocol or standard, or combination of communication protocols or standards, such as 3rd Generation Partnership Project Long-Term Evolution (3GPP LTE), Fifth Generation New Radio (5G NR), and so forth. Multiple wireless linksmay be aggregated in a carrier aggregation to provide a higher data rate for the UE. Multiple wireless linksfrom multiple base stationsmay be configured for Coordinated Multipoint (CoMP) communication with the UE.

120 140 121 122 140 150 121 122 102 104 150 121 122 102 110 150 160 170 The base stationsare collectively a Radio Access Network(e.g., RAN, Evolved Universal Terrestrial Radio Access Network, E-UTRAN, 5G NR RAN or NR RAN). The base stationsandin the RANare connected to a core network. The base stationsandconnect, atandrespectively, to the core networkthrough an NG2 interface for control-plane signaling and using an NG3 interface for user-plane data communications when connecting to a 5G core network, or using an S1 interface for control-plane signaling and user-plane data communications when connecting to an Evolved Packet Core (EPC) network. The base stationsandcan communicate using an Xn Application Protocol (XnAP) through an Xn interface or using an X2 Application Protocol (X2AP) through an X2 interface, at, to exchange user-plane and control-plane data. The user equipmentmay connect, via the core network, to public networks, such as the Internetto interact with a remote service.

2 FIG. 2 FIG. 200 110 120 110 120 110 202 204 204 206 208 120 140 204 110 206 208 202 202 110 202 204 206 208 202 204 206 208 120 202 204 illustrates an example device diagramof the user equipmentand the base stations. The user equipmentand the base stationsmay include additional functions and interfaces that are omitted fromfor the sake of clarity. The user equipmentincludes antennas, a radio frequency front end(RF front end), an LTE transceiver, and a 5GNR transceiverfor communicating with base stationsin the RAN. The RF front endof the user equipmentcan couple or connect the LTE transceiver, and the 5GNR transceiverto the antennasto facilitate various types of wireless communication. The antennasof the user equipmentmay include an array of multiple antennas that are configured similar to or differently from each other. The antennasand the RF front endcan be tuned to, and/or be tunable to, one or more frequency bands defined by the 3GPP LTE and 5G NR communication standards and implemented by the LTE transceiver, and/or the 5GNR transceiver. Additionally, the antennas, the RF front end, the LTE transceiver, and/or the 5GNR transceivermay be configured to support beamforming for the transmission and reception of communications with the base stations. By way of example and not limitation, the antennasand the RF front endcan be implemented for operation in sub-gigahertz bands, sub-6 GHZ bands, and/or above 6 GHz bands that are defined by the 3GPP LTE and 5G NR communication standards.

110 210 212 212 210 212 214 110 214 110 210 110 The user equipmentalso includes processor(s)and computer-readable storage media(CRM). The processormay be a single core processor or a multiple core processor composed of a variety of materials, such as silicon, polysilicon, high-K dielectric, copper, and so on. The computer-readable storage media described herein excludes propagating signals. CRMmay include any suitable memory or storage device such as random-access memory (RAM), static RAM (SRAM), dynamic RAM (DRAM), non-volatile RAM (NVRAM), read-only memory (ROM), or Flash memory useable to store device dataof the user equipment. The device dataincludes user data, multimedia data, beamforming codebooks, applications, and/or an operating system of the user equipment, which are executable by processor(s)to enable user-plane communication, control-plane signaling, and user interaction with the user equipment.

212 216 216 110 216 202 204 206 208 In some implementations, the CRMmay also include a beamforming manager. Alternately or additionally, the beamforming managermay be implemented in whole or part as hardware logic or circuitry integrated with or separate from other components of the user equipment. The beamforming managercan communicate with the antennas, the RF front end, the LTE transceiver, and/or the 5G NR transceiverto implement techniques for cross-carrier hybrid automatic repeat request described herein.

120 120 120 252 254 254 256 258 110 254 120 256 258 252 252 120 252 254 256 258 252 254 256 258 110 2 FIG. The device diagram for the base stations, shown in, includes a single network node (e.g., a gNode B). The functionality of the base stationsmay be distributed across multiple network nodes or devices and may be distributed in any fashion suitable to perform the functions described herein. The base stationsinclude antennas, a radio frequency front end(RF front end), one or more LTE transceivers, and/or one or more 5G NR transceiversfor communicating with the UE. The RF front endof the base stationscan couple or connect the LTE transceiversand the 5G NR transceiversto the antennasto facilitate various types of wireless communication. The antennasof the base stationsmay include an array of multiple antennas that are configured similar to or differently from each other. The antennasand the RF front endcan be tuned to, and/or be tunable to, one or more frequency band defined by the 3GPP LTE and 5G NR communication standards, and implemented by the LTE transceivers, and/or the 5G NR transceivers. Additionally, the antennas, the RF front end, the LTE transceivers, and/or the 5G NR transceiversmay be configured to support beamforming, such as Massive-MIMO, for the transmission and reception of communications with the UE.

120 260 262 262 260 262 264 120 264 120 260 110 The base stationsalso include processor(s)and computer-readable storage media(CRM). The processormay be a single core processor or a multiple core processor composed of a variety of materials, such as silicon, polysilicon, high-K dielectric, copper, and so on. CRMmay include any suitable memory or storage device such as random-access memory (RAM), static RAM (SRAM), dynamic RAM (DRAM), non-volatile RAM (NVRAM), read-only memory (ROM), or Flash memory useable to store device dataof the base stations. The device dataincludes network scheduling data, radio resource management data, beamforming codebooks, applications, and/or an operating system of the base stations, which are executable by processor(s)to enable communication with the user equipment.

262 266 266 120 266 256 258 110 150 CRMalso includes a base station manager. Alternately or additionally, the base station managermay be implemented in whole or part as hardware logic or circuitry integrated with or separate from other components of the base stations. In at least some aspects, the base station managerconfigures the LTE transceiversand the 5G NR transceiversfor communication with the user equipment, as well as communication with a core network, such as the core network.

120 268 266 120 120 110 120 270 266 The base stationsinclude an inter-base station interface, such as an Xn and/or X2 interface, which the base station managerconfigures to exchange user-plane and control-plane data between other base stations, to manage the communication of the base stationswith the user equipment. The base stationsinclude a core network interfacethat the base station managerconfigures to exchange user-plane and control-plane data with core network functions and/or entities.

3 FIG. 300 300 300 300 100 300 302 304 302 304 300 110 120 110 120 illustrates an example block diagramof a wireless network stack model(stack). The stackcharacterizes a communication system for the example environment, in which various aspects of beam failure reporting can be implemented. The stackincludes a user planeand a control plane. Upper layers of the user planeand the control planeshare common lower layers in the stack. Wireless devices, such as the UEor the base station, implement each layer as an entity for communication with another device using the protocols defined for the layer. For example, a UEuses a Packet Data Convergence Protocol (PDCP) entity to communicate to a peer PDCP entity in a base stationusing the PDCP.

306 308 310 312 306 306 The shared lower layers include a physical (PHY) layer, a Media Access Control (MAC) layer, a Radio Link Control (RLC) layer, and a PDCP layer. The PHY layerprovides hardware specifications for devices that communicate with each other. As such, the PHY layerestablishes how devices connect to each other, assists in managing how communication resources are shared among devices, and the like.

308 308 The MAC layerspecifies how data is transferred between devices. Generally, the MAC layerprovides a way in which data packets being transmitted are encoded and decoded into bits as part of a transmission protocol.

310 300 310 The RLC layerprovides data transfer services to higher layers in the stack. Generally, the RLC layerprovides error correction, packet segmentation and reassembly, and management of data transfers in various modes, such as acknowledged, unacknowledged, or transparent modes.

312 300 312 302 304 The PDCP layerprovides data transfer services to higher layers in the stack. Generally, the PDCP layerprovides transfer of user planeand control planedata, header compression, ciphering, and integrity protection.

312 302 304 302 314 316 318 320 131 314 314 316 320 318 320 302 Above the PDCP layer, the stack splits into the user-planeand the control-plane. Layers of the user planeinclude an optional Service Data Adaptation Protocol (SDAP) layer, an Internet Protocol (IP) layer, a Transmission Control Protocol/User Datagram Protocol (TCP/UDP) layer, and an application layer, which transfers data using the wireless link. The optional SDAP layeris present in 5G NR networks. The SDAP layermaps a Quality of Service (QoS) flow for each data radio bearer and marks QoS flow identifiers in uplink and downlink data packets for each packet data session. The IP layerspecifies how the data from the application layeris transferred to a destination node. The TCP/UDP layeris used to verify that data packets intended to be transferred to the destination node reached the destination node, using either TCP or UDP for data transfers by the application layer. In some implementations, the user planemay also include a data services layer (not shown) that provides data transport services to transport application data, such as IP packets including web browsing content, video content, image content, audio content, or social media content.

304 324 326 324 324 110 110 110 120 120 110 120 324 The control planeincludes a Radio Resource Control (RRC) layerand a Non-Access Stratum (NAS) layer. The RRC layerestablishes and releases connections and radio bearers, broadcasts system information, or performs power control. The RRC layeralso controls a resource control state of the UEand causes the UEto perform operations according to the resource control state. Example resource control states include a connected state (e.g., an RRC connected state) or a disconnected state, such as an inactive state (e.g., an RRC inactive state) or an idle state (e.g., an RRC idle state). In general, if the UEis in the connected state, the connection with the base stationis active. In the inactive state, the connection with the base stationis suspended. If the UEis in the idle state, the connection with the base stationis released. Generally, the RRC layersupports 3GPP access but does not support non-3GPP access (e.g., WLAN communications).

326 328 330 110 150 326 The NAS layerprovides support for mobility management (e.g., using a Fifth-Generation Mobility Management (SGMM) layer) and packet data bearer contexts (e.g., using a Fifth-Generation Session Management (SGSM) layer) between the UEand entities or functions in the core network, such as an Access and Mobility Management Function (AMF) of the core networkor the like. The NAS layersupports both 3GPP access and non-3GPP access.

110 302 304 300 120 110 140 In the UE, each layer in both the user planeand the control planeof the stackinteracts with a corresponding peer layer or entity in the base station, a core network entity or function, and/or a remote service, to support user applications and control operation of the UEin the RAN.

4 FIG. 402 404 402 410 411 412 413 414 404 410 402 illustrates an air interface resource that extends between a user equipment and a base station and with which various aspects of beam failure reporting can be implemented. The air interface resourcecan be divided into resource units, each of which occupies some intersection of frequency spectrum and elapsed time. A portion of the air interface resourceis illustrated graphically in a grid or matrix having multiple resource blocks, including resource blocks,,,. An example of a resource unittherefore includes at least one resource block. As shown, time is depicted along the horizontal dimension as the abscissa axis, and frequency is depicted along the vertical dimension as the ordinate axis. The air interface resource, as defined by a given communication protocol or standard, may span any suitable specified frequency range and/or may be divided into intervals of any specified duration. Increments of time can correspond to, for example, milliseconds (mSec). Increments of frequency can correspond to, for example, megahertz (MHz).

121 404 402 410 131 110 411 406 411 406 411 408 408 410 420 406 408 420 404 410 420 4 FIG. In example operations generally, the base stationallocates portions (e.g., resource units) of the air interface resourcefor uplink and downlink communications. Each resource blockof network access resources may be allocated to support respective wireless communication linkof multiple user equipment. In the lower left corner of the grid, the resource blockmay span, as defined by a given communication protocol, a specified frequency rangeand comprise multiple subcarriers or frequency sub-bands. The resource blockmay include any suitable number of subcarriers (e.g., 12) that each correspond to a respective portion (e.g., 15 kHz) of the specified frequency range(e.g., 180 kHz). The resource blockmay also span, as defined by the given communication protocol, a specified time intervalor time slot (e.g., lasting approximately one-half millisecond or 7 orthogonal frequency-division multiplexing (OFDM) symbols). The time intervalincludes subintervals that may each correspond to a symbol, such as an OFDM symbol. As shown in, each resource blockmay include multiple resource elements(REs) that correspond to, or are defined by, a subcarrier of the frequency rangeand a subinterval (or symbol) of the time interval. Alternatively, a given resource elementmay span more than one frequency subcarrier or symbol. Thus, a resource unitmay include at least one resource block, at least one resource element, and so forth.

110 121 402 266 110 266 110 266 410 110 4 FIG. In example implementations, multiple user equipment(one of which is shown) are communicating with the base stationthrough access provided by portions of the air interface resource. The base station manager(not shown in) may determine a respective type or amount of information (e.g., data or control information) to be communicated (e.g., transmitted) by the user equipment. For example, the base station managercan determine that each user equipmentis to transmit a different respective amount of information. The base station managerthen allocates one or more resource blocksto each user equipmentbased on the determined amount of information.

266 266 420 110 410 110 266 420 410 110 110 Additionally or in the alternative to block-level resource grants, the base station managermay allocate resource units at an element-level. Thus, the base station managermay allocate one or more resource elementsor individual subcarriers to different user equipment. By so doing, one resource blockcan be allocated to facilitate network access for multiple user equipment. Accordingly, the base station managermay allocate, at various granularities, one or up to all subcarriers or resource elementsof a resource blockto one user equipmentor divided across multiple user equipment, thereby enabling higher network utilization or increased spectrum efficiency.

266 402 404 410 420 404 110 404 110 110 206 208 404 402 The base station managercan therefore allocate air interface resourceby resource unit, resource block, frequency carrier, time interval, resource element, frequency subcarrier, time subinterval, symbol, spreading code, some combination thereof, and so forth. Based on respective allocations of resource units, the resource manager can transmit respective messages to the multiple user equipmentindicating the respective allocation of resource unitsto each user equipment. Each message may enable a respective user equipmentto queue the information or configure the LTE transceiver, the 5G NR transceiver, or both to communicate via the allocated resource unitsof the air interface resource.

110 110 121 In aspects, if a user equipmenthas initiated a beam recovery procedure and has not completed the procedure, the user equipmenttransmits, to the base station, a first MAC Protocol Data Unit (PDU) including a first MAC Control element (CE) on a first uplink grant. In another aspect, the first MAC CE is associated with a first Logical Channel Identifier (LCID), and the first LCID is used to identify the first MAC CE.

121 121 121 121 In another aspect, the first MAC CE is associated with a first MAC subheader in the first MAC PDU. The first MAC subheader includes an LCID field that includes the value of the first LCID. The base stationparses the first MAC PDU. If the base stationdetects a MAC subheader where the LCID field includes the first LCID, the base stationdetermines that this MAC subheader is the first MAC subheader, and the base stationexpects the first MAC CE will follow the first MAC subheader.

110 110 In another aspect, the first MAC CE comprises a first field that indicates one or more Synchronization Signal Blocks (SSBs). Each SSB is associated with a downlink transmit beam. The first field is a bitmap in which each bit of the bitmap is associated with an SSB. If the value of a bit is set to a first value, the user equipmentselects the SSB associated with the bit. If the value of the bit is set to a second value, the user equipmentdoes not select the SSB associated with the bit.

110 110 In a further aspect, the first field comprises of one or more SSB ID subfields. If an SSB is selected by the user equipment, the SSB ID of the SSB is provided in one of SSB ID subfields. For example, the user equipmentselects an SSB if the Reference Signal Received Quality (RSRP) of the Synchronization Symbol (SS) block, (e.g., SS-RSRP) is above a threshold (e.g., rsrp-ThresholdSSB defined as in 3GPP TS 38.321 MAC). In another example, the user equipment selects an SSB if the Channel State Information (CSI) Reference Signals (RSs) of the SSB are above a threshold (e.g., rsrp-ThresholdCSI-RS defined in 3GPP TS 38.321 MAC).

121 110 110 110 In aspects, the first uplink grant is a Type 1 configured grant. The base stationsends a configuration of the Type 1 configured grant to the user equipment. The configuration includes an uplink grant. Once the user equipmentcompletes the configuration, the user equipmentcan use the configured grant to transmit uplink data.

121 121 110 110 110 In another aspect, the first uplink grant is a Type 2 configured grant. The base stationsends a configuration of the Type 2 configured grant. Then the base stationsends the user equipmentDownlink Control Information (e.g., (DCI) on a Physical Downlink Control Channel (PDCCH) that is addressed to a Configured Scheduling Radio Network Temporary Identity (CS-RNTI) of the user equipment. Then the user equipmentcan use the configured grant to transmit uplink data. The CS-RNTI is given in the configuration of Type 2 configured grant. Alternatively, the first uplink grant can also be a grant given in a DCI on PDCCH addressed to CS-RNTI.

121 110 110 121 In another aspect, based on receiving the first MAC PDU, the base stationdetermines that the user equipmenthas detected a beam failure problem and that the user equipmentis requesting to change the downlink transmit beam to one of the beams associated with the SSBs indicated in the first MAC CE. The base stationeither randomly selects or selects a first downlink transmit beam with lighter traffic load from among the beams that are associated with the SSBs indicated in the first MAC CE. The first downlink transmit beam is associated with a first SSB.

121 121 In a further aspect, a second MAC PDU comprises a second MAC CE that includes a bitmap or an SSB ID field. In the bitmap, the base stationsets the bit associated the first SSB to the first value. Alternatively, the base stationprovides the SSB ID of the first SSB in the SSB ID field.

110 110 110 In a further aspect, the second MAC CE is associated with a second LCID. The LCID is used to identify the second MAC CE. The second MAC CE is associated with a second MAC subheader. The second MAC subheader includes an LCID field that includes the value of the second LCID. In this way, when the user equipmentdetects a MAC subheader with the LCID field including the second LCID, the user equipmentdetermines that the MAC subheader is the second MAC subheader, and the user equipmentexpects that the second MAC CE follows the second MAC subheader.

121 121 In a further aspect, the base stationtransmits the second MAC PDU on the first downlink transmit beam. Alternatively, the base stationtransmits the second MAC PDU on every downlink transmit beam that is associated with the SSBs indicated in the first MAC CE.

110 110 110 If the user equipmentreceives the second MAC CE, it considers that the beam recovery procedure is completed. However, if a random-access procedure triggered due to beam recovery is still running, the user equipmentaborts the random-access procedure, or the user equipmentstarts to detect a beam failure for the first SSB.

500 5 FIG. Example methodis described with reference toin accordance with one or more aspects of beam failure reporting. Generally, any of the components, modules, methods, and operations described herein can be implemented using software, firmware, hardware (e.g., fixed logic circuitry), manual processing, or any combination thereof. Some operations of the example methods may be described in the general context of executable instructions stored on computer-readable storage memory that is local and/or remote to a computer processing system, and implementations can include software applications, programs, functions, and the like. Alternatively or in addition, any of the functionality described herein can be performed, at least in part, by one or more hardware logic components, such as, and without limitation, Field-programmable Gate Arrays (FPGAs), Application-specific Integrated Circuits (ASICs), Application-specific Standard Products (ASSPs), System-on-a-chip systems (SoCs), Complex Programmable Logic Devices (CPLDs), and the like.

5 FIG. 500 illustrates example method(s)of beam failure reporting. The order in which the method blocks are described are not intended to be construed as a limitation, and any number of the described method blocks can be combined or skipped in any order to implement a method or an alternate method.

502 110 504 At block, a user equipment (e.g., the user equipment) receives a first uplink grant. At block, the user equipment initiates a beam recovery procedure.

506 121 At block, based on the beam recovery procedure determining that a beam has failed, the user equipment transmits, using the first uplink grant, a first Media Access Control Protocol Data Unit including a first MAC Control Element that indicates a first Synchronization Signal Block and a second Synchronization Signal Block. The transmission causes the base station (e.g., the base station) to determine that, based on receiving the first Synchronization Signal Block, the beam failure was detected by the user equipment on the first Synchronization Signal Block.

In the following some examples are described:

500 120 110 Example 1: A method () of reporting a beam failure to a base station () by a user equipment () in a wireless communication network, the method comprising:

502 receiving (), by the user equipment, a first uplink grant;

504 initiating (), by the user equipment, a beam recovery procedure; and

506 based on the beam recovery procedure determining that a beam has failed, transmitting (), using the first uplink grant, a first Media Access Control Protocol Data Unit including a first MAC Control Element that indicates a first Synchronization Signal Block and a second Synchronization Signal Block, the transmitting being effective to cause the base station to determine that, based on receiving the first Synchronization Signal Block, the beam failure was detected by the user equipment on the first Synchronization Signal Block.

Example 2: The method of example 1, wherein the first MAC Control Element is associated with a first Logical Channel Identifier, and wherein the first Logical Channel Identifier is usable to identify the first MAC Control Element.

Example 3: The method of example 2, wherein the first MAC Control Element is associated with a first MAC subheader in the first Media Access Control Protocol Data Unit, wherein the first MAC subheader has a Logical Channel Identifier field whose value is the first Logical Channel Identifier, and wherein the first MAC subheader precedes the first MAC Control Element in the Media Access Control Protocol Data Unit.

Example 4: The method of any preceding example, wherein the first MAC Control Element contains a first field that indicates one or more Synchronization Signal Blocks, each Synchronization Signal Block being associated with a downlink transmit beam.

Example 5: The method of example 4, wherein the first field is a bitmap, wherein each bit of the bitmap is associated with a Synchronization Signal Block, the method further comprising:

selecting, by the user equipment, the Synchronization Signal Block associated with the bit if the value of the bit is set to a first value; or

not selecting the Synchronization Signal Block associated with the bit if the value of the bit is set to a second value.

Example 6: The method of example 4 or example 5, wherein the first field consists of one or more Synchronization Signal Block Identifier subfields, wherein if the user equipment selects a Synchronization Signal Block, the Synchronization Signal Block Identifier of the Synchronization Signal Block is provided in one of Synchronization Signal Block Identifier subfields.

Example 7: The method of example 5 or example 6, the method further comprising:

selecting, by the user equipment, the Synchronization Signal Block if a Reference Signal Received Quality of the Synchronization Signal Block of the Synchronization Signal Block is above a threshold.

Example 8: The method of example 3, the method further comprising:

selecting, by the user equipment, a Synchronization Signal Block if Channel State Information Reference Signals of the Synchronization Signal Block are above a threshold.

Example 9: The method of any preceding example, wherein the first uplink grant is a type-1 configured grant, the method further comprising:

receiving, by the user equipment, a configuration of the type-1 configured grant, the configuration including an uplink grant; and

transmitting uplink data using the configuration.

Example 10: The method of any of examples 1 to 8, wherein the first uplink grant is a type-2 configured grant, the method further comprising:

receiving by the user equipment, a configuration of type-2 configured grant;

receiving a Downlink Control Information on a Physical Downlink Control Channel addressed to Configured Scheduling Radio Network Temporary Identity of the user equipment; and

transmitting uplink data using the configured grant, wherein the configuration of type-2 configured grant includes the Configured Scheduling Radio Network Temporary Identity.

Example 11: The method of any preceding example, wherein the first uplink grant is a grant given in a Downlink Control Information on Physical Downlink Control Channel addressed to Configured Scheduling Radio Network Temporary Identity.

Example 12: The method of any preceding example, further comprising:

based on receiving a second MAC Control Element, determining, by the user equipment that the beam recovery procedure is completed.

Example 13: The method of example 12, wherein a random-access procedure, which was triggered due to the beam recovery procedure, is still running, the method further comprising:

aborting, by the user equipment, the random-access procedure.

110 Example 14: A user equipment () comprising:

202 a wireless transceiver ();

210 a processor (); and

212 memory () comprising instructions executable by the processor to perform any one of the methods of examples 1 to 13.

110 120 Example 15: A method of managing a beam failure report from a user equipment () by a base station () in a wireless communication network, the method comprising:

receiving, by the base station, a first Media Access Control Protocol Data Unit including a first MAC Control Element that indicates a first Synchronization Signal Block and a second Synchronization Signal Block;

determining, based on receiving the first Synchronization Signal Block, that the user equipment detected a beam failure on the first Synchronization Signal Block; and

selecting a first downlink transmit beam with a lighter traffic load among beams that are associated with the Synchronization Signal Blocks indicated in the first MAC Control Element, the first downlink transmit beam being associated with the first Synchronization Signal Block.

Example 16: The method of example 15, wherein the base station randomly selects the first downlink transmit beam.

Example 17: The method of example 15 or example 16, wherein a second Media Access Control Protocol Data Unit includes a second MAC Control Element that includes a bitmap, the method further comprising:

setting, by the base station, a bit associated with the first Synchronization Signal Block to a first value in the bitmap.

Example 18: The method of any of examples 15 to 17, wherein a second Media Access Control Protocol Data Unit includes a second MAC Control Element that includes a Synchronization Signal Block Identifier field, the method further comprising:

providing, by the base station, the Synchronization Signal Block Identifier of the first Synchronization Signal Block in the Synchronization Signal Block Identifier field.

Example 19: The method of example 17 to example 18, wherein the second MAC Control Element is associated with a second Logical Channel Identifier, the Logical Channel Identifier being usable to identify the second MAC Control Element.

Example 20: The method of example 19, wherein the second MAC Control Element is associated with a second MAC subheader in the second Media Access Control Protocol Data Unit, wherein the second MAC subheader has a Logical Channel Identifier field whose value is the second Logical Channel Identifier, and wherein the second MAC subheader precedes the second MAC Control Element in the second Media Access Control Protocol Data Unit.

Example 21: The method of any of examples 17 to 20, further comprising:

transmitting, by the base station, the second Media Access Control Protocol Data Unit on the first downlink transmit beam.

Example 22: The method of any of examples 17 to 21, further comprising:

transmitting, by the base station, the second Media Access Control Protocol Data Unit on every downlink transmit beam that is associated with the Synchronization Signal Blocks indicated in the first MAC Control Element.

120 Example 23: A base station () comprising:

252 a wireless transceiver ();

260 a processor (); and

262 memory () comprising instructions executable by the processor to perform any one of the methods of examples 15 to 22.

Although aspects of beam failure reporting have been described in language specific to features and/or methods, the subject of the appended claims is not necessarily limited to the specific features or methods described. Rather, the specific features and methods are disclosed as example implementations of beam failure reporting, and other equivalent features and methods are intended to be within the scope of the appended claims. Further, various different aspects are described, and it is to be appreciated that each described aspect can be implemented independently or in connection with one or more other described aspects.