Method and apparatus for facilitating spatial relationship indication for uplink control channels and sounding reference signals

Abstract

To provide an apparatus, a method, and a computer-readable medium for facilitating spatial relationship indication for an uplink control channel and an SRS.SOLUTION: An exemplary method for wireless communication in UE includes determining, on the basis of a rule, a default uplink transmission beam for transmitting an uplink transmission when no uplink transmission beam is configured by a base station for the uplink transmission. The exemplary method also includes transmitting the uplink transmission to the base station on the default uplink transmission beam.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 62 / 861,882, filed June 14, 2019, entitled "METHODS AND APPARATUS TO FACILITATE SPATIAL RELATION INDICATION FOR UPLINK CONTROL CHANNEL AND SOUNDING REFERENCE SIGNALS," and U.S. Patent Application No. 16 / 781,784, filed February 4, 2020, entitled "METHODS AND APPARATUS TO FACILITATE SPATIAL RELATION INDICATION FOR UPLINK CONTROL CHANNEL AND SOUNDING REFERENCE SIGNALS," both of which are expressly incorporated herein by reference in their entireties.

[0002] The present disclosure relates generally to communication systems, and more particularly to communication systems that utilize beams. [Background technology]

[0003] Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may utilize multiple-access technologies capable of supporting communication with multiple users by sharing available system resources. Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.

[0004] These multiple access technologies have been adopted in various telecommunications standards to provide common protocols that enable different wireless devices to communicate at city, national, regional, and even global levels. An exemplary telecommunications standard is 5G New Radio (NR). 5G NR is part of the ongoing mobile broadband evolution promulgated by the 3rd Generation Partnership Project (3GPP®) to meet new requirements associated with latency, reliability, security, scalability (e.g., with the Internet of Things (IoT)), and other requirements. 5G NR includes services associated with enhanced mobile broadband (eMBB), massive machine-type communications (mMTC), and ultra-reliable low-latency communications (URLLC). Some aspects of 5G NR may be based on the 4G Long Term Evolution (LTE) standard. Further improvements to 5G NR technology are needed. These improvements may also be applicable to other multiple access technologies and telecommunications standards that employ these technologies. Summary of the Invention [Means for solving the problem]

[0005] The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an exhaustive overview of all possible aspects, nor is it intended to identify key or critical elements of all aspects or to delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.

[0006] In certain aspects of the present disclosure, a method, a computer-readable medium, and an apparatus are provided. An exemplary apparatus for wireless communication in a user equipment (UE) determines, based on rules, a default uplink transmission beam for transmitting an uplink transmission when an uplink transmission beam is not configured by a base station for the uplink transmission. The exemplary apparatus also transmits the uplink transmission to the base station on the default uplink transmission beam.

[0007] In another aspect of the present disclosure, a method, a computer-readable medium, and an apparatus are provided. An exemplary apparatus for wireless communication at a base station transmits downlink transmissions to a user equipment (UE) on a downlink beam. The exemplary apparatus also receives uplink transmissions from the UE on a default uplink transmission beam when the base station has not configured an uplink transmission beam for the uplink transmission.

[0008] To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of the various aspects may be employed, and this description is intended to include all such aspects and their equivalents. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 illustrates an example of a wireless communication system and access network. [Figure 2A] A figure showing an example of a first 5G / NR frame. [Figure 2B] FIG. 1 illustrates an example of a DL channel within a 5G / NR subframe. [Figure 2C] A figure showing an example of a second 5G / NR frame. [Figure 2D]FIG. 1 illustrates an example of an UL channel within a 5G / NR subframe. [Figure 3] FIG. 1 illustrates an example of a base station and user equipment (UE) in an access network. [Figure 4] FIG. 1 illustrates an example communication flow between a base station and a UE in accordance with the teachings disclosed herein. [Figure 5] 1 is a flowchart of a method of wireless communication in a UE in accordance with the teachings disclosed herein. [Figure 6] 1 is a flowchart of a method of wireless communication in a UE in accordance with the teachings disclosed herein. [Figure 7] 1 is a flowchart of a method of wireless communication in a UE in accordance with the teachings disclosed herein. [Figure 8] 1 is a flowchart of a method of wireless communication in a UE in accordance with the teachings disclosed herein. [Figure 9] 1 is a flowchart of a method of wireless communication in a UE in accordance with the teachings disclosed herein. [Figure 10] FIG. 2 is a conceptual data flow diagram illustrating data flow between different means / components in an exemplary apparatus. [Figure 11] FIG. 1 illustrates an example of a hardware implementation of an apparatus utilizing a processing system. [Figure 12] 1 is a flowchart of a method of wireless communication in a base station in accordance with the teachings disclosed herein. [Figure 13] FIG. 2 is a conceptual data flow diagram illustrating data flow between different means / components in an exemplary apparatus. [Figure 14] FIG. 1 illustrates an example of a hardware implementation of an apparatus utilizing a processing system. DETAILED DESCRIPTION OF THE INVENTION

[0010] The detailed description set forth below with reference to the accompanying drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of the various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form to avoid obscuring such concepts.

[0011] Several aspects of a telecommunications system will now be presented with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, components, circuits, processes, algorithms, etc. (collectively referred to as "elements"). These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends on the particular application and design constraints imposed on the overall system.

[0012] As an example, an element, or any portion of an element, or any combination of elements, may be implemented as a "processing system" including one or more processors. Examples of processors include microprocessors, microcontrollers, graphics processing units (GPUs), central processing units (CPUs), application processors, digital signal processors (DSPs), reduced instruction set computing (RISC) processors, systems-on-chips (SoCs), baseband processors, field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gate logic, discrete hardware circuits, and other suitable hardware configured to perform various functions described throughout this disclosure. One or more processors in a processing system may execute software. Software should be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software components, applications, software applications, software packages, routines, subroutines, objects, executable files, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

[0013] Thus, in one or more exemplary embodiments, the functions described may be implemented in hardware, software, or any combination thereof. If implemented in software, the functions may be stored on or encoded as one or more instructions or code on a computer-readable medium. Computer-readable media include computer storage media. A storage medium may be any available medium that can be accessed by a computer. By way of example, and not limitation, such computer-readable media may comprise random access memory (RAM), read-only memory (ROM), electrically erasable programmable ROM (EEPROM), optical disk storage, magnetic disk storage, other magnetic storage devices, combinations of the above types of computer-readable media, or any other medium usable for storing computer-executable code in the form of instructions or data structures accessible by a computer.

[0014] As used herein, the term computer-readable medium is expressly defined to include any type of computer-readable storage device and / or storage disk, to exclude propagating signals, and to exclude transmission media. As used herein, "computer-readable medium," "machine-readable medium," "computer-readable memory," and "machine-readable memory" are used interchangeably.

[0015] 1 illustrates an example of a wireless communication system and access network 100. The wireless communication system (also referred to as a wireless wide area network (WWAN)) includes a base station 102, a UE 104, an evolved packet core (EPC) 160, and another core network 190 (e.g., 5G core (5GC)). The base station 102 may include a macrocell (a high-power cellular base station) and / or a small cell (a low-power cellular base station). A macrocell includes a base station. A small cell includes a femtocell, a picocell, and a microcell.

[0016] A base station 102 configured for 4G LTE (collectively referred to as Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) may interface with the EPC 160 through a first backhaul link 132 (e.g., an S1 interface). A base station 102 configured for 5G NR (collectively referred to as Next Generation RAN (NG-RAN)) may interface with the core network 190 through a second backhaul link 184. In addition to other functions, the base stations 102 may perform one or more of the following functions: forwarding user data, encryption and decryption of radio channels, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection setup and release, load balancing, distribution for non-access stratum (NAS) messages, NAS node selection, synchronization, radio access network (RAN) sharing, multimedia broadcast multicast service (MBMS), subscriber and equipment tracking, RAN information management (RIM), paging, positioning, and delivery of alert messages. The base stations 102 may communicate with each other directly or indirectly (e.g., through the EPC 160 or the core network 190) via a third backhaul link 134 (e.g., an X2 interface). The third backhaul link 134 may be wired or wireless.

[0017] The base stations 102 may communicate wirelessly with the UEs 104. Each of the base stations 102 may provide communication coverage for a respective geographic coverage area 110. Overlapping geographic coverage areas 110 may exist. For example, a small cell 102' may have a coverage area 110' that overlaps with the coverage area 110 of one or more macro base stations 102. A network including both small cells and macro cells may be referred to as a heterogeneous network. A heterogeneous network may also include a Home Evolved Node B (eNB) (HeNB), which may serve a closed group known as a Closed Subscriber Group (CSG). The communication link 120 between the base station 102 and the UE 104 may include uplink (UL) transmissions (also called reverse link) from the UE 104 to the base station 102 and / or downlink (DL) transmissions (also called forward link) from the base station 102 to the UE 104. The communication link 120 may use multiple-input multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and / or transmit diversity. The communication link may be through one or more carriers. The base station 102 / UE 104 may use spectrum with a bandwidth of up to Y MHz per carrier (e.g., 5, 10, 15, 20, 100, 400 MHz, etc.) allocated in carrier aggregation with up to a total of Yx MHz (x component carriers) used for transmission in each direction. The carriers may or may not be adjacent to each other. The carrier allocation may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated for DL ​​than UL). The component carriers may include a primary component carrier and one or more secondary component carriers. The primary component carrier may be referred to as a primary cell (PCell), and the secondary component carrier may be referred to as a secondary cell (SCell).

[0018] Several UEs 104 may communicate with each other using device-to-device (D2D) communication links 158. The D2D communication links 158 may use DL / UL WWAN spectrum. The D2D communication links 158 may use one or more sidelink channels, such as a physical sidelink broadcast channel (PSBCH), a physical sidelink discovery channel (PSDCH), a physical sidelink shared channel (PSSCH), and a physical sidelink control channel (PSCCH). The D2D communication may be through various wireless D2D communication systems, such as, for example, FlashLinQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based on the IEEE 802.11 standard, LTE, or NR.

[0019] The wireless communication system may further include a Wi-Fi access point (AP) 150 communicating with a Wi-Fi station (STA) 152 via a communication link 154 in the 5 GHz unlicensed frequency spectrum. When communicating in the unlicensed frequency spectrum, the STA 152 / AP 150 may perform clear channel assessment (CCA) prior to communicating to determine if a channel is available.

[0020] The small cell 102' may operate in a licensed and / or unlicensed frequency spectrum. When operating in an unlicensed frequency spectrum, the small cell 102' may utilize NR and use the same 5 GHz unlicensed frequency spectrum used by the Wi-Fi AP 150. The small cell 102' utilizing NR in the unlicensed frequency spectrum may enhance coverage to and / or increase capacity of the access network.

[0021] The base station 102, whether a small cell 102′ or a large cell (e.g., a macro base station), may include and / or be referred to as an eNB, gNodeB (gNB), or another type of base station. Some base stations, such as the gNB 180, communicate with the UE 104 and may operate in the traditional sub-6 GHz spectrum, millimeter wave (mmW) frequencies, and / or sub-mmW frequencies. When the gNB 180 operates at mmW or sub-mmW frequencies, it may be referred to as an mmW base station. Extremely high frequency (EHF) is the RF portion of the electromagnetic spectrum. EHF ranges from 30 GHz to 300 GHz and has a wavelength between 1 millimeter and 10 millimeters. Radio waves in that band are sometimes referred to as millimeter waves. Sub-mmW can extend down to frequencies as low as 3 GHz, with wavelengths of 100 millimeters. The very high frequency (SHF) band extends between 3 GHz and 30 GHz and is also called centimeter wave. Communications using the mmW / quasi-mmW radio frequency band (e.g., 3 GHz to 300 GHz) have significant path loss and short distances. The mmW base station 180 may utilize beamforming 182 with the UE 104 to compensate for the significant path loss and short distances. The base station 180 and the UE 104 may each include multiple antennas, such as antenna elements, antenna panels, and / or antenna arrays, to facilitate beamforming.

[0022] The base station 180 may transmit beamformed signals to the UE 104 in one or more transmit directions 182′. The UE 104 may receive beamformed signals from the base station 180 in one or more receive directions 182″. The UE 104 may also transmit beamformed signals to the base station 180 in one or more transmit directions. The base station 180 may receive beamformed signals from the UE 104 in one or more receive directions. The base station 180 / UE 104 may perform beam training to determine the best receive direction and transmit direction for each of the base station 180 / UE 104. The transmit direction and receive direction for the base station 180 may or may not be the same. The transmit direction and receive direction for the UE 104 may or may not be the same.

[0023] The EPC 160 may include a mobility management entity (MME) 162, other MMEs 164, a serving gateway 166, a multimedia broadcast multicast service (MBMS) gateway 168, a broadcast multicast service center (BM-SC) 170, and a packet data network (PDN) gateway 172. The MME 162 may be in communication with a home subscriber server (HSS) 174. The MME 162 is a control node that handles signaling between the UE 104 and the EPC 160. Generally, the MME 162 handles bearer and connection management. All user Internet Protocol (IP) packets are forwarded through the serving gateway 166, which is itself connected to the PDN gateway 172. The PDN gateway 172 provides UE IP address allocation and other functions. The PDN gateway 172 and the BM-SC 170 are connected to an IP service 176. The IP services 176 may include the Internet, an intranet, an IP Multimedia Subsystem (IMS), PS streaming services, and / or other IP services. The BM-SC 170 may provide functionality for MBMS user service provisioning and delivery. The BM-SC 170 may serve as an entry point for content provider MBMS transmissions, may be used to authorize and initiate MBMS bearer services within the public land mobile network (PLMN), and may be used to schedule MBMS transmissions. The MBMS gateway 168 may be used to distribute MBMS traffic to base stations 102 belonging to a multicast broadcast single frequency network (MBSFN) area that broadcasts a particular service, and may be responsible for session management (start / stop) and collecting eMBMS-related charging information.

[0024] The core network 190 may include an access and mobility management function (AMF) 192, other AMFs 193, a session management function (SMF) 194, and a user plane function (UPF) 195. The AMF 192 may be in communication with a unified data management (UDM) 196. The AMF 192 is a control node that handles signaling between the UE 104 and the core network 190. Generally, the AMF 192 provides QoS flow and session management. All user Internet Protocol (IP) packets are forwarded through the UPF 195. The UPF 195 provides UE IP address allocation and other functions. The UPF 195 is connected to IP services 197. The IP services 197 may include the Internet, an intranet, an IP multimedia subsystem (IMS), PS streaming services, and / or other IP services.

[0025] A base station may include and / or be referred to as a gNB, Node B, eNB, access point, base transceiver station, radio base station, radio transceiver, transceiver function, basic service set (BSS), extended service set (ESS), transmit / receive point (TRP), or some other suitable terminology. The base station 102 provides an access point to the EPC 160 or core network 190 for the UE 104. Examples of the UE 104 include a mobile phone, smartphone, session initiation protocol (SIP) phone, laptop, personal digital assistant (PDA), satellite radio, global positioning system, multimedia device, video device, digital audio player (e.g., MP3 player), camera, game console, tablet, smart device, wearable device, vehicle, electricity meter, gas pump, large or small cooking appliance, health management device, implant, sensor / actuator, display, or any other similar function device. Some of the UE 104 may be referred to as IoT devices (e.g., parking meter, gas pump, toaster, vehicle, heart monitor, etc.). The UE 104 may also be referred to as a station, mobile station, subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, remote terminal, handset, user agent, mobile client, client, or some other suitable terminology.

[0026] Referring again to FIG. 1 , in some aspects, the UE 104 may be configured to manage one or more aspects of wireless communication via determining a default spatial relationship for an uplink control channel and / or SRS. As an example, in FIG. 1 , the UE 104 may include a UE spatial relationship component 198 configured to rule-based determine a default uplink transmit beam for transmitting an uplink transmission when no uplink transmit beam is configured by the base station for the uplink transmission. The UE spatial relationship component 198 may also be configured to transmit the uplink transmission to the base station on the default uplink transmit beam.

[0027] Still referring to FIG. 1, in some aspects, base station 180 may be configured to manage one or more aspects of wireless communications via monitoring a default spatial relationship to an uplink control channel and / or SRS. As an example, in FIG. 1, base station 180 may include a base station transmission configuration indication (TCI) component 199 configured to transmit downlink transmissions to user equipment (UE) on downlink beams. The exemplary base station TCI component 199 may also be configured to receive uplink transmissions from UEs on a default uplink transmission beam when the base station has not configured an uplink transmission beam for the uplink transmission.

[0028] As used herein, the term "spatial relationship" may be used to refer to UE-side information, and the term "TCI" may be used to refer to base station-side information. However, in some instances, the terms "spatial relationship" and "TCI" may be used interchangeably.

[0029] While the following description focuses on uplink communications, the concepts described herein may be applicable to downlink and / or sidelink communications. Additionally, while the following description may focus on 5G / NR, the concepts described herein may be applicable to other similar fields, such as LTE, LTE-A, CDMA, GSM, and / or other wireless technologies, where a default spatial relationship for an uplink control channel and / or SRS may improve communications. For example, the techniques disclosed herein facilitate reducing signaling overhead and facilitate efficient beam management.

[0030] Figure 2A is a diagram 200 illustrating an example of a first subframe in a 5G / NR frame structure. Figure 2B is a diagram 230 illustrating an example of a DL channel in a 5G / NR subframe. Figure 2C is a diagram 250 illustrating an example of a second subframe in a 5G / NR frame structure. Figure 2D is a diagram 280 illustrating an example of a UL channel in a 5G / NR subframe. The 5G / NR frame structure may be FDD, where for a particular set of subcarriers (carrier system bandwidth), subframes within the set of subcarriers are dedicated to either DL or UL, or TDD, where for a particular set of subcarriers (carrier system bandwidth), subframes within the set of subcarriers are dedicated to both DL and UL. In the example given by Figures 2A and 2C, the 5G / NR frame structure is assumed to be TDD, subframe 4 is configured with slot format 28 (mostly with DL), where D is DL, U is UL, and X is flexible for use between DL and UL, and subframe 3 is configured with slot format 34 (mostly with UL). Subframes 3 and 4 are shown with slot formats 34 and 28, respectively, but any particular subframe may be configured with any of the various available slot formats 0 through 61. Slot formats 0 and 1 are all DL and UL, respectively. The other slot formats 2 through 61 include a mix of DL, UL, and flexible symbols. The UE is configured with the slot format through a received slot format indicator (SFI) (either dynamically through DL control information (DCI) or semi-statically / statically through radio resource control (RRC) signaling). Please note that the following description also applies to the 5G / NR frame structure, which is TDD.

[0031] Other wireless communication technologies may have different frame structures and / or different channels. A frame (10 ms) may be divided into 10 equally sized subframes (1 ms). Each subframe may contain one or more time slots. A subframe may also contain a minislot, which may contain 7, 4, or 2 symbols. Each slot may contain 7 or 14 symbols depending on the slot configuration. In slot configuration 0, each slot may contain 14 symbols, and in slot configuration 1, each slot may contain 7 symbols. Symbols on the DL may be cyclic prefix (CP) OFDM (CP-OFDM) symbols. Symbols on the UL may be CP-OFDM symbols (for high-throughput scenarios) or discrete Fourier transform (DFT) spread OFDM (DFT-s-OFDM) symbols (also called single-carrier frequency division multiple access (SC-FDMA) symbols) (limited to a single stream transmission for power-limited scenarios). The number of slots in a subframe is based on the slot configuration and numerology. In slot configuration 0, the different numerologies μ 0-5 allow 1, 2, 4, 8, 16, and 32 slots per subframe, respectively. In slot configuration 1, the different numerologies 0-2 allow 2, 4, and 8 slots per subframe, respectively. Therefore, for slot configuration 0 and numerology μ, 14 symbols / slot and 2 μ There are slots / subframes. The subcarrier spacing and symbol length / duration depend on the numerology. The subcarrier spacing is 2 μ* μ may be equal to 15 kHz, where μ is a numerology between 0 and 5. Thus, numerology μ=0 has a subcarrier spacing of 15 kHz, and numerology μ=5 has a subcarrier spacing of 480 kHz. Symbol length / duration is inversely related to subcarrier spacing. Figures 2A-2D give an example of slot configuration 0 with 14 symbols per slot and numerology μ=2 with 4 slots per subframe. The slot duration is 0.25 ms, the subcarrier spacing is 60 kHz, and the symbol duration is approximately 16.67 μs.

[0032] A resource grid can be used to represent the frame structure. Each time slot contains a resource block (RB) (also called a physical RB (PRB)) that spans 12 consecutive subcarriers. The resource grid is divided into multiple resource elements (RE). The number of bits carried by each RE depends on the modulation scheme.

[0033] As shown in Figure 2A, some of the REs carry reference (pilot) signals (RS) for the UE. The RSs are also called demodulation RSs (DM-RSs) (for a particular configuration, 100x is the port number) for channel estimation at the UE. x , but other DM-RS configurations are possible), and channel state information reference signals (CSI-RS). The RSs may also include beam measurement RSs (BRS), beam improvement RSs (BRRS), and phase tracking RSs (PT-RS).

[0034] FIG. 2B illustrates an example of various DL channels within a subframe of a frame. The physical downlink control channel (PDCCH) carries DCI within one or more control channel elements (CCEs), each containing nine RE groups (REGs), with each REG containing four consecutive REs in an OFDM symbol. A primary synchronization signal (PSS) may be within symbol 2 of a particular subframe of the frame. The PSS is used by the UE 104 to determine subframe / symbol timing and physical layer identity. A secondary synchronization signal (SSS) may be within symbol 4 of a particular subframe of the frame. The SSS is used by the UE to determine the physical layer cell identity group number and radio frame timing. Based on the physical layer identity and the physical layer cell identity group number, the UE can determine a physical cell identifier (PCI). Based on the PCI, the UE can determine the location of the DM-RS described above. The Physical Broadcast Channel (PBCH), which carries the Master Information Block (MIB), may be logically grouped with the PSS and SSS to form the Synchronization Signal (SS) / PBCH block. The MIB provides the number of RBs in the system bandwidth and the System Frame Number (SFN). The Physical Downlink Shared Channel (PDSCH) carries user data and broadcast system information not transmitted over the PBCH, such as the System Information Block (SIB), and paging messages.

[0035] As shown in FIG. 2C, some of the REs carry DM-RS (denoted as R for one particular configuration, although other DM-RS configurations are possible) for channel estimation at the base station. The UE may transmit DM-RS for the physical uplink control channel (PUCCH) and DM-RS for the physical uplink shared channel (PUSCH). The PUSCH DM-RS may be transmitted in the first one or two symbols of the PUSCH. The PUCCH DM-RS may be transmitted in different configurations depending on whether a short or long PUCCH is transmitted and the particular PUCCH format used. The UE may transmit a sounding reference signal (SRS). The SRS may be transmitted in the last symbol of a subframe. The SRS may have a comb structure, and the UE may transmit the SRS in one of the combs. The SRS may be used by the base station for channel quality estimation to enable frequency-dependent scheduling on the UL.

[0036] 2D shows an example of various UL channels within a subframe of a frame. The PUCCH, in one configuration, may be arranged as shown. The PUCCH carries uplink control information (UCI) such as scheduling requests, channel quality indicators (CQIs), precoding matrix indicators (PMIs), rank indicators (RIs), and HARQ ACK / NACK feedback. The PUSCH carries data and may be further used to carry buffer status reports (BSRs), power headroom reports (PHRs), and / or UCIs.

[0037] 3 is a block diagram of a base station 310 in communication with a UE 350 in an access network. In the DL, IP packets from the EPC 160 may be provided to a controller / processor 375. The controller / processor 375 implements Layer 3 and Layer 2 functions. Layer 3 includes a Radio Resource Control (RRC) layer, and Layer 2 includes a Service Data Adaptation Protocol (SDAP) layer, a Packet Data Convergence Protocol (PDCP) layer, a Radio Link Control (RLC) layer, and a Medium Access Control (MAC) layer. The controller / processor 375 is configured to handle RRC layer functions associated with broadcasting system information (e.g., MIBs, SIBs), RRC connection control (e.g., RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release), inter-Radio Access Technology (RAT) mobility, and measurement configuration for UE measurement reporting; PDCP layer functions associated with header compression / decompression, security (encryption, decryption, integrity protection, integrity verification), and handover support functions; RLC layer functions associated with forwarding upper layer packet data units (PDUs), error correction via ARQ, concatenation, segmentation, and reassembly of RLC service data units (SDUs), re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; and mapping between logical channels and transport channels, multiplexing MAC SDUs onto transport blocks (TBs), and MAC SDUs from TBs. It provides MAC layer functions associated with demultiplexing of SDUs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

[0038] The transmit (TX) processor 316 and receive (RX) processor 370 implement Layer 1 functionality associated with various signal processing functions. Layer 1, including the physical (PHY) layer, may include error detection on transport channels, forward error correction (FEC) coding / decoding of transport channels, interleaving, rate matching, mapping onto physical channels, modulation / demodulation of physical channels, and MIMO antenna processing. The TX processor 316 handles mapping to signal constellations based on various modulation schemes (e.g., binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), M-phase shift keying (M-PSK), M-ary quadrature amplitude modulation (M-QAM)). The coded and modulated symbols may then be split into parallel streams. Each stream may then be mapped to OFDM subcarriers, multiplexed with a reference signal (e.g., a pilot) in the time and / or frequency domain, and then combined together using an inverse fast Fourier transform (IFFT) to generate a physical channel carrying a time-domain OFDM symbol stream. The OFDM streams are spatially precoded to generate multiple spatial streams. Channel estimates from a channel estimator 374 may be used to determine coding and modulation schemes and for spatial processing. The channel estimates may be derived from a reference signal and / or channel condition feedback transmitted by the UE 350. Each spatial stream may then be provided to a different antenna 320 via a separate transmitter 318TX. Each transmitter 318TX may modulate an RF carrier with the respective spatial stream for transmission.

[0039] In the UE 350, each receiver 354RX receives a signal through its respective antenna 352. Each receiver 354RX recovers information modulated onto an RF carrier and provides the information to a receive (RX) processor 356. The TX processor 368 and the RX processor 356 implement Layer 1 functions associated with various signal processing functions. The RX processor 356 may perform spatial processing on the information to recover any spatial streams destined for the UE 350. Multiple spatial streams may be combined into a single OFDM symbol stream by the RX processor 356 when destined for the UE 350. The RX processor 356 then converts the OFDM symbol stream from the time domain to the frequency domain using a fast Fourier transform (FFT). The frequency-domain signal comprises a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier, as well as the reference signal, are recovered and demodulated by determining the most likely signal constellation point transmitted by the base station 310. These soft decisions may be based on channel estimates calculated by a channel estimator 358. The soft decisions are then decoded and deinterleaved to recover the data and control signals originally transmitted by the base station 310 on the physical channel. The data and control signals are then provided to a controller / processor 359, which implements Layer 3 and Layer 2 functions.

[0040] The controller / processor 359 may be associated with a memory 360 that stores program codes and data. The memory 360 may be referred to as a computer-readable medium. In the UL, the controller / processor 359 performs demultiplexing between transport and logical channels, packet reassembly, decryption, header decompression, and control signal processing to recover IP packets from the EPC 160. The controller / processor 359 is also responsible for error detection using an ACK and / or NACK protocol to support HARQ operations.

[0041] Similar to the functionality described with respect to DL transmission by base station 310, controller / processor 359 provides RRC layer functionality associated with system information (e.g., MIB, SIB) collection, RRC connection, and measurement reporting; PDCP layer functionality associated with header compression / decompression and security (encryption, decryption, integrity protection, integrity verification); RLC layer functionality associated with transfer of upper layer PDUs, error correction via ARQ, concatenation, segmentation, and reassembly of RLC SDUs, re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto TBs, demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction via HARQ, priority handling, and logical channel prioritization.

[0042] Channel estimates derived by the channel estimator 358 from a reference signal or feedback transmitted by the base station 310 may be used by the TX processor 368 to select an appropriate coding and modulation scheme to facilitate spatial processing. The spatial streams generated by the TX processor 368 may be provided to different antennas 352 via separate transmitters 354TX. Each transmitter 354TX may modulate an RF carrier with a respective spatial stream for transmission.

[0043] UL transmissions are processed at the base station 310 in a manner similar to that described with respect to the receiver functions at the UE 350. Each receiver 318RX receives a signal through its respective antenna 320. Each receiver 318RX recovers the information modulated onto the RF carrier and provides the information to the RX processor 370.

[0044] The controller / processor 375 may be associated with a memory 376 that stores program codes and data. The memory 376 may be referred to as a computer-readable medium. In the UL, the controller / processor 375 performs demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, and control signal processing to recover IP packets from the UE 350. The IP packets from the controller / processor 375 may be provided to the EPC 160. The controller / processor 375 is also responsible for error detection using an ACK and / or NACK protocol to support HARQ operations.

[0045] At least one of the TX processor 368, the RX processor 356, and the controller / processor 359 may be configured to perform aspects associated with the UE spatial relations component 198 of FIG.

[0046] At least one of the TX processor 316, the RX processor 370, and the controller / processor 375 may be configured to perform aspects associated with the base station TCI component 199 in FIG.

[0047] Example techniques disclosed herein enable a UE to determine a default uplink transmission beam for transmitting an uplink transmission when an uplink transmission beam is not configured by a base station for the uplink transmission (e.g., when an uplink transmission beam is not explicitly configured by the base station). For example, to reduce signaling overhead, the spatial relationship information may be an optional parameter for the uplink transmission (e.g., PUCCH and / or SRS) and thus may not be explicitly configured by the base station for the UE, e.g., in RRC signaling. In the absence of explicit configuration of the spatial relationship information from the base station, the techniques disclosed herein enable the UE to implicitly determine a default uplink transmission beam for transmitting the uplink transmission. For example, the UE may apply one or more rules to determine a default uplink transmission beam for transmitting the uplink transmission. The UE may then transmit the uplink transmission on the default uplink transmission beam. Providing a method for a UE to determine a default uplink transmission beam without configuration for the default uplink transmission beam may help reduce signaling overhead (e.g., between the UE and the base station) for more efficient use of wireless resources.

[0048] 4 illustrates exemplary wireless communications 400 between a base station 402 and a UE 404 as presented herein. One or more aspects of the base station 402 may be implemented by the base station 102 / 180 of FIG. 1 and / or the base station 310 of FIG. 3. One or more aspects of the UE 404 may be implemented by the UE 104 of FIG. 1 and / or the UE 350 of FIG. 3.

[0049] 4 includes one base station 402 in communication with one UE 404, in additional or alternative examples, the base station 402 may be in communication with any suitable quantity of UEs and / or other base stations, and / or the UE 404 may be in communication with any suitable quantity of base stations and / or other UEs. Thus, while some of the transmissions between the base station 402 and the UE 404 are described as uplink and downlink transmissions, in other examples, any of the transmissions may additionally or alternatively be sidelink transmissions.

[0050] In the illustrated example, a base station 402 and a UE 404 are in communication. For example, the base station 402 may transmit a downlink transmission 410 that is received by the UE 404. The downlink transmission 410 may be a downlink shared channel (e.g., a PDSCH) and / or a downlink control channel (e.g., a PDCCH). In the illustrated example, the base station 402 transmits the downlink transmission 410 on a downlink beam 412 that is used to transmit the downlink transmission (e.g., the downlink transmission 410). The UE 404 may receive the downlink transmission 410 via a beam 414 that is used to receive the downlink transmission (e.g., the downlink transmission 410) from the base station 402.

[0051] At 420, the UE 404 may determine to transmit an uplink transmission. For example, the UE 404 may determine to transmit an uplink control channel (e.g., PUCCH), an SRS, and / or a scheduling request (SR). In the illustrated example of FIG. 4, an uplink transmit beam for the uplink transmission is not configured by the base station 402. For example, to reduce signaling overhead, the spatial relationship information may be an optional parameter for the PUCCH and / or SRS and thus may not be explicitly configured by the base station 402 for the UE 404, for example, in RRC (e.g., via "PUCCH-config" and / or "SRS-config").

[0052] Thus, the techniques disclosed herein enable a UE to determine an uplink transmit beam for transmitting an uplink transmission without explicit configuration for each uplink transmission. For example, at 430, the UE 404 determines a default uplink transmit beam for transmitting an uplink transmission. As described below, the UE 404 may determine the default uplink transmit beam based on one or more parameters associated with a beam used to receive a downlink transmission from the base station 402 (e.g., one or more parameters associated with the beam 414 used to receive the downlink transmission 410).

[0053] At 440, the base station 402 selects a beam to monitor to receive the uplink transmission. As described below, the base station 402 may select a beam to monitor to receive the uplink transmission based on one or more parameters associated with the beam used to transmit the downlink transmission to the UE 404 (e.g., one or more parameters associated with the beam 412 used to transmit the downlink transmission 410).

[0054] After determining (e.g., at 430) the default uplink transmission beam, the UE 404 transmits an uplink transmission 450, which is received by the base station 402. In the illustrated example, the UE 404 transmits the uplink transmission 450 on the determined default uplink transmission beam (e.g., beam 452) used to transmit the uplink transmission (e.g., uplink transmission 450). The base station 402 may receive the uplink transmission 450 via a beam 454 used to receive the uplink transmission (e.g., uplink transmission 450) from the UE 404. In the illustrated example, the base station 402 may determine the beam 454 at 440.

[0055] 4 shows the UE 404 determining a default uplink transmit beam at 430 and substantially simultaneously the base station 402 selecting a beam to monitor at 440, although the relative timing is an example. For example, in some examples, the base station 402 may perform the selection of a beam to monitor (e.g., at 440) before the UE 404 performs the default uplink transmit beam determination (e.g., at 430), while in other examples, the base station 402 may perform the selection of a beam to monitor (e.g., at 440) after the UE 404 performs the default uplink transmit beam determination (e.g., at 430).

[0056] In some examples, the UE 404 may be configured to operate using beam correspondence, where one or more parameters of a default uplink transmit beam may correspond to a beam used to receive downlink transmissions. For example, when the UE 404 is operating using beam correspondence, one or more parameters of the default uplink transmit beam 452 may correspond to the beam 414 used to receive downlink transmissions 410. As a further example, the phase offset and / or gain used by the UE 404 for antenna elements in an antenna array to transmit the default uplink transmit beam may be the same as or based on the phase offset and / or gain used to receive downlink transmissions.

[0057] In some examples, the downlink transmission 410 may be a downlink shared channel (e.g., a PDSCH). In some such examples, the UE 404 may determine 430 the default uplink transmission beam 452 by selecting a beam corresponding to a transmission configuration indication (TCI) state identifier associated with the downlink shared channel. For example, the UE 404 may select a beam corresponding to the smallest TCI state identifier of the activated TCI states associated with the downlink shared channel. In some examples, the UE 404 may select a beam corresponding to a particular TCI state identifier of the TCI state associated with the downlink shared channel.

[0058] Similarly, in some examples, the base station 402 may select 440 a beam 454 to monitor to receive the uplink transmission 450 based on a TCI state identifier associated with the downlink shared channel. For example, the base station 402 may select a beam corresponding to the smallest TCI state identifier of the activated TCI states associated with the downlink shared channel. In some examples, the base station 402 may select a beam corresponding to a particular TCI state identifier of the TCI state associated with the downlink shared channel.

[0059] In some examples, the UE 404 may select a beam corresponding to the last successfully received downlink shared channel beam after a threshold period. Similarly, in some examples, the base station 402 may select a beam corresponding to the last successfully received downlink shared channel beam after a threshold period. For example, when a downlink shared channel transmission is successfully received by the UE 404, the UE 404 may transmit an ACK signal to the base station 402 indicating that the downlink shared channel transmission was successfully received. Because there may be a delay (e.g., round-trip time plus additional time for transmission / signal decoding, processing, etc.) between the transmission of the downlink shared channel transmission and the reception of the ACK signal, the UE 404 may wait a threshold period after successfully receiving the downlink shared channel before selecting and / or transmitting using a beam corresponding to the received downlink shared beam. Similarly, the base station 402 may wait a threshold period before selecting and / or monitoring a beam corresponding to a successfully received downlink shared channel. The threshold period associated with the UE waiting time before selecting and / or transmitting may be the same as or different from the threshold period associated with the base station waiting time before selecting and / or monitoring.

[0060] In some examples, the downlink transmission 410 may be a downlink control channel (e.g., a PDCCH). In some examples, the UE 404 may determine 430 the default uplink transmission beam 452 by selecting a beam associated with a particular control resource set (CORESET) that includes a set of resources and / or parameters used to carry the PDCCH and / or DCI. In some such examples, the particular CORESET may correspond to a CORESET with a minimum CORESET identifier in a slot last monitored by the UE 404. In some examples, the particular CORESET may correspond to a CORESET with a minimum CORESET identifier among a set of configured CORESETs. In some examples, the UE 404 may receive a CORESET identifier for the particular CORESET via RRC signaling and / or a medium access control-control element (MAC-CE).

[0061] Similarly, in some examples, the base station 402 may select 440 a beam 454 to monitor to receive the uplink transmission 450 based on the beam associated with the particular CORESET. In such examples, the particular CORESET may correspond to the CORESET with the smallest CORESET identifier in the slot last monitored by the UE 404. In some examples, the particular CORESET may correspond to the CORESET with the smallest CORESET identifier among a set of configured CORESETs. In some examples, the base station 402 may transmit the CORESET identifier for the particular CORESET via RRC signaling and / or MAC-CE.

[0062] 4 depicts the UE 404 may determine 430 the default uplink transmit beam 452 after receiving the downlink transmission 410, but in some examples, the UE 404 may determine 430 the default uplink transmit beam 452 before and / or without receiving the downlink transmission 410. For example, in some examples, a CORESET may be configured and the UE 404 may determine 430 the default uplink transmit beam 452 based on a received beam associated with the smallest CORESET ID. Thus, it should be appreciated that the downlink transmission providing the CORESET configuration may be the downlink transmission 410 and / or any other preceding downlink transmission from the base station 402 to the UE 404. Thus, it may be appreciated that in some examples, the UE 404 may first determine whether a CORESET is configured for the UE 404 and then determine the default uplink transmit beam 452 accordingly. For example, if the UE 404 determines that a CORESET is configured, the UE 404 may select a beam associated with the particular CORESET. In some such examples, if the UE 404 determines that a CORESET is not configured, the UE 404 may select a beam based on the PDSCH.

[0063] In some examples, the UE 404 may determine 430 a default uplink transmission beam 452 by selecting a beam indicated in the DCI. Similarly, the base station 402 may select 440 a beam 454 to monitor to receive the uplink transmission 450 based on the beam indicated in the DCI.

[0064] In some examples, the UE 404 may communicate with multiple transmit / receive points (TRPs). In some such examples, the UE 404 may determine 430 a default uplink transmit beam 452 for each of the TRPs based on the corresponding beam used to receive the respective downlink transmission. Similarly, the base station 402 may select 440 a beam to monitor for each of the TRPs based on the corresponding downlink beam (e.g., the beam 412 used to transmit the downlink transmission 410 to the UE 404).

[0065] While the illustrated example of FIG. 4 depicts determining a default uplink transmission beam for transmitting an uplink transmission, in some examples, the UE 404 may determine the default uplink transmission beam based on the type of uplink transmission. For example, the UE 404 may determine a first default uplink transmission beam for transmitting an uplink control channel, a second default uplink transmission beam for transmitting an SRS, and a third default uplink transmission beam for transmitting an SR. In some examples, the first default uplink transmission beam, the second default uplink transmission beam, and / or the third default uplink transmission beam may be the same default uplink transmission beam. In other examples, at least one of the first default uplink transmission beam, the second default uplink transmission beam, and the third default uplink transmission beam may be different from another one of the default uplink transmission beams.

[0066] In some examples, the UE 404 may not be operating using beam support. In some such examples, the UE 404 may receive default uplink spatial relationship information from the base station 402 for determining a default uplink transmit beam. In some examples, the UE 404 may receive the default uplink spatial relationship information from the base station 402 via RRC signaling, MAC-CE signaling, and / or DCI signaling. The UE 404 may then use the default uplink transmit beam to transmit multiple subsequent uplink transmissions. In this manner, when an uplink transmit beam is not configured for an uplink transmission, the UE 404 may be able to determine a default uplink transmit beam for one or more uplink transmissions without receiving signaling for each respective uplink transmission.

[0067] 5-9 are flowcharts of a method of wireless communication as disclosed herein. The method may be performed by a UE (e.g., UE 104, UE 350, UE 404, UE 1350, device 1002 / 1002′, processing system 1114, which may include memory 360, may be the entire UE 350, or may be a component of the UE 350, such as TX processor 368, RX processor 356, and / or controller / processor 359). Optional aspects are illustrated using dashed lines. The example flowcharts of FIGS. 5-9 facilitate a UE performing fast and efficient beam selection for transmitting uplink transmissions (e.g., when no uplink beam is configured for the uplink transmission), which may result in reduced overhead signaling between the UE and the base station.

[0068] FIG. 5 is a flowchart 500 of a method of wireless communication as described in accordance with the teachings disclosed herein. At 502, the UE determines a default uplink transmit beam for transmitting an uplink transmission based on a rule when no uplink transmit beam is configured by a base station for the uplink transmission, e.g., as described with respect to 430 of FIG. 4 . For example, a default uplink transmit beam determination component 1018 may facilitate determining a default uplink transmit beam for transmitting the uplink transmission. For example, to reduce signaling overhead, spatial relationship information for an uplink transmission (e.g., an uplink transmit beam) may be an optional parameter and thus may not be explicitly configured for the UE by the base station, e.g., in RRC signaling. In the absence of explicit configuration of spatial relationship information from the base station (e.g., when no uplink transmit beam is configured by the base station), the UE implicitly determines a default uplink transmit beam for transmitting the uplink transmission. In some examples, the UE may determine that a default uplink transmission beam corresponds to a beam used to receive downlink transmissions, where parameters for the default uplink transmission beam may correspond to that beam. In some examples, the UE may communicate with multiple TRPs. In some such examples, for each TRP, the UE may determine a default uplink transmission beam based on the corresponding beam used to receive downlink transmissions.

[0069] In some examples, at 503, the UE may determine whether a CORESET is configured, as described with respect to 430 of FIG. 4. For example, the default uplink transmit beam determination component 1018 may facilitate determining whether a CORESET is configured. In some such examples, the UE may select a beam based on whether a CORESET is configured. For example, the UE may use a CORESET corresponding to the smallest CORESET identifier when a CORESET is configured, and may use a PDSCH when a CORESET is not configured.

[0070] In some examples, the UE may determine, based on the different uplink transmissions, respective default uplink transmission beams for the corresponding uplink transmissions at 504. For example, the default uplink transmit beam determination component 1018 may facilitate determining a first default uplink transmission beam for transmitting an uplink control channel, a second default uplink transmission beam for transmitting an SRS, and a third default uplink transmission beam for transmitting an SR. In some examples, one or more of the respective default uplink transmission beams may be the same default uplink transmission beam.

[0071] At 506, the UE transmits an uplink transmission to the base station on a default uplink transmission beam, e.g., as described with respect to uplink transmission 450 of FIG. 4. For example, the transmitting component 1006 may facilitate transmitting the uplink transmission on the default uplink transmission beam. In some examples, the uplink transmission includes at least one of an uplink control channel (e.g., PUCCH), an SRS, or an SR.

[0072] 6-9 are flowcharts of methods of wireless communication. The exemplary methods of FIGS. 6-9 may be used to determine a default uplink transmit beam. For example, the exemplary methods of FIGS. 6-9 may facilitate implementing 502 of FIG. 5.

[0073] 6 is a flowchart 600 of a method of wireless communication as described in accordance with the teachings disclosed herein. In the example of FIG. 6, the UE is operating using beam correspondence such that parameters for a default uplink transmit beam correspond to a beam used to receive downlink transmissions.

[0074] At 602, the UE may receive a downlink shared channel from a base station, eg, as described with respect to downlink transmission 410 of FIG. 4. For example, a receiving component 1004 may facilitate reception of the downlink shared channel.

[0075] At 604, the UE may determine a default uplink transmission beam based on a beam used to receive a downlink transmission (e.g., a downlink shared channel), e.g., as described with respect to 430 of FIG. 4. For example, the TCI state identifier component 1008 and / or the shared channel beam component 1010 may facilitate determining a default uplink transmission beam based on a beam used to receive a downlink transmission.

[0076] In some examples, the UE may select a beam corresponding to a minimum TCI state identifier of an activated TCI state associated with the downlink shared channel at 606. For example, the TCI state identifier component 1008 may facilitate selecting a beam corresponding to a minimum TCI state identifier of an activated TCI state associated with the downlink shared channel.

[0077] In some examples, the UE may select a beam corresponding to a particular TCI state identifier of a TCI state associated with the downlink shared channel at 608. For example, the TCI state identifier component 1008 may facilitate the selection of a beam corresponding to a particular TCI state identifier of a TCI state associated with the downlink shared channel.

[0078] In some examples, the UE may select 610 a beam corresponding to the last successfully received downlink shared channel beam after a threshold period. For example, the shared channel beam component 1010 may facilitate selection of the beam corresponding to the last successfully received downlink shared channel beam after a threshold period.

[0079] 7 is a flowchart 700 of a method of wireless communication as described in accordance with the teachings disclosed herein. In the example of FIG. 7, the UE is operating using beam correspondence such that parameters for a default uplink transmit beam correspond to a beam used to receive downlink transmissions.

[0080] At 702, the UE may receive a CORESET identifier for a particular CORESET via at least one of RRC or MAC-CE, as described with respect to downlink transmission 410 of FIG. 4. For example, receiving component 1004 may facilitate receiving the CORESET identifier for the particular CORESET.

[0081] At 704, the UE may select a beam associated with a particular CORESET, e.g., as described with respect to 430 of FIG. 4. For example, the CORESET processing component 1012 may facilitate the selection of a beam associated with a particular CORESET. In some examples, the particular CORESET may correspond to a CORESET with a minimum CORESET identifier among the slots last monitored by the UE. In some examples, the particular CORESET may correspond to a CORESET with a minimum CORESET identifier among a set of configured CORESETs.

[0082] 8 is a flowchart 800 of a method of wireless communication as described in accordance with the teachings disclosed herein. In the example of FIG. 8, the UE is operating using beam correspondence such that parameters for a default uplink transmit beam correspond to a beam used to receive downlink transmissions.

[0083] At 802, the UE may receive DCI from a base station, eg, as described with respect to downlink transmission 410 of Figure 4. For example, a receiving component 1004 may facilitate receiving the DCI from the base station.

[0084] At 804, the UE may select a beam indicated in the DCI, e.g., as described with respect to 430 of FIG. 4. For example, DCI processing component 1014 may facilitate the selection of the beam indicated in the DCI. In some examples, the DCI may carry TCI status information (e.g., when the DCI schedules a PDSCH and carries corresponding TCI status information). In some such examples, when the TCI status information is available to the UE, the UE may determine which receive beam to use to receive downlink transmissions on that beam, which may be a QCL with the TCI status information. For example, in CORESET, there may be an option to enable or disable a “tci-PresentInDCI” parameter in RRC, which indicates whether the DCI carries TCI status information for the scheduled shared channel. In some examples, the TCI status may be associated with one or more DL reference signals and a corresponding QCL (quasi-co-location) type. For example, QCL type D may relate to receive beam parameters. In such examples, the UE may select a beam based on receive beam parameters used to receive the downlink beam configured by the DCI.

[0085] 9 is a flowchart 900 of a method of wireless communication as described in accordance with the teachings disclosed herein. At 902, a UE may receive from a base station default uplink spatial relationship information for determining a default uplink transmit beam for transmitting an uplink transmission when an uplink transmit beam for the uplink transmission is not configured, e.g., as described with respect to downlink transmission 410 of FIG. 4. For example, receiving component 1004 may facilitate receiving the default uplink spatial relationship information. In some examples, the UE may receive the default uplink spatial relationship information via at least one of RRC signaling, MAC-CE signaling, and / or DCI signaling.

[0086] At 904, the UE may determine a default uplink transmit beam for subsequent multiple uplink transmissions based on the default uplink spatial relationship information, e.g., as described with respect to 430 of FIG. 4. For example, spatial relationship information processing component 1016 may facilitate determining the default uplink transmit beam based on the default uplink spatial relationship information.

[0087] 10 is a conceptual data flow diagram 1000 illustrating data flow between different means / components in an exemplary apparatus 1002 in communication with a base station 1050. The apparatus 1002 may be a UE or a component of a UE. The apparatus 1002 includes a receiving component 1004, a transmitting component 1006, a TCI state identifier component 1008, a shared channel beam component 1010, a CORESET processing component 1012, a DCI processing component 1014, a spatial relationship information processing component 1016, and a default uplink transmit beam determination component 1018. The base station 1050 may include the same or similar components as shown with respect to the base station 102 / 180 of FIG. 1, the base station 310 of FIG. 3, the base station 402 of FIG. 4, and / or the apparatus 1302 / 1302′ of FIG. 13 / FIG. 14.

[0088] The receiving component 1004 may be configured to receive various types of signals / messages and / or other information from other devices, including, for example, base station 1050. The messages / information may be received via the receiving component 1004 and may be provided to one or more components of the apparatus 1002 for further processing and / or use in performing various operations. For example, the receiving component 1004 may be configured to receive downlink transmissions including, for example, a downlink shared channel, CORESET, DCI signaling, default spatial relationship information, MAC-CE signaling, and / or RRC signaling (e.g., as described with respect to 602, 702, 802, and / or 902).

[0089] The transmitting component 1006 may be configured to transmit various types of signals / messages and / or other information to other devices, including, for example, the base station 1050. For example, the transmitting component 1006 may be configured to transmit uplink transmissions on a default uplink transmit beam (e.g., as described with respect to 506).

[0090] The TCI state identifier component 1008 may be configured to select a beam corresponding to the smallest TCI state identifier of the activated TCI states associated with the downlink shared channel (e.g., as described with respect to 604, 606, and / or 608) and / or to select a beam corresponding to a particular TCI state identifier of the TCI state associated with the downlink shared channel.

[0091] The shared channel beam component 1010 may be configured to select a beam corresponding to the last successfully received downlink shared channel beam after a threshold period (e.g., as described with respect to 604 and / or 610).

[0092] The CORESET processing component 1012 may be configured to select a beam associated with a particular CORESET (e.g., as described with respect to 704). In some examples, the particular CORESET includes the smallest CORESET identifier among the slots last monitored by the UE. In some examples, the particular CORESET includes the smallest CORESET identifier among a set of configured CORESETs.

[0093] The DCI processing component 1014 may be configured to select the beam indicated in the DCI (e.g., as described with respect to 804).

[0094] The spatial relationship information processing component 1016 may be configured to determine a default uplink transmit beam for subsequent multiple uplink transmissions based on the default uplink spatial relationship information (e.g., as described with respect to 904).

[0095] The default uplink transmit beam determination component 1018 may be configured to rule-based determine a default uplink transmit beam for transmitting an uplink transmission when no uplink transmit beam is configured by the base station for the uplink transmission (e.g., as described with respect to 502 and / or 504). For example, the default uplink transmit beam determination component 1018 may use a beam indication provided by the TCI state identifier component 1008, the shared channel beam component 1010, the CORESET processing component 1012, the DCI processing component 1014, and / or the spatial relationship information processing component 1016 to determine the default uplink transmit beam. In some examples, the default uplink transmit beam determination component 1018 may determine a respective default uplink transmit beam for a corresponding uplink transmission type (e.g., SRS, uplink control channel, and / or SR) (e.g., as described with respect to 504).

[0096] The apparatus may include additional components that perform each of the blocks of the algorithms in the flowcharts of Figures 5-9 described above. Thus, each block in the flowcharts of Figures 5-9 described above may be performed by a component, and the apparatus may include one or more of those components. The components may be one or more hardware components specifically configured to perform the described process / algorithm, implemented by a processor configured to perform the described process / algorithm, stored in a computer-readable medium for implementation by a processor, or some combination thereof.

[0097] 11 is a diagram 1100 illustrating an example hardware implementation of an apparatus 1002′ utilizing a processing system 1114. The processing system 1114 may be implemented using a bus architecture, represented generally by bus 1124. The bus 1124 may include any number of interconnected buses and bridges, depending on the specific application and overall design constraints of the processing system 1114. The bus 1124 couples together various circuits, including the processor 1104, components 1004, 1006, 1008, 1010, 1012, 1014, 1016, 1018, and one or more processors and / or hardware components, represented by computer-readable medium / memory 1106. The bus 1124 may also couple various other circuits, such as timing sources, peripheral devices, voltage regulators, and power management circuits, which are well known in the art and therefore will not be described further.

[0098] The processing system 1114 may be coupled to a transceiver 1110. The transceiver 1110 is coupled to one or more antennas 1120. The transceiver 1110 provides a means for communicating with various other devices over a transmission medium. The transceiver 1110 receives signals from one or more antennas 1120, extracts information from the received signals, and provides the extracted information to the processing system 1114, particularly to the receiving component 1004. In addition, the transceiver 1110 receives information from the processing system 1114, particularly from the transmitting component 1006, and generates signals to be applied to the one or more antennas 1120 based on the received information. The processing system 1114 includes a processor 1104 coupled to a computer-readable medium / memory 1106. The processor 1104 is responsible for general processing, including executing software stored on the computer-readable medium / memory 1106. The software, when executed by the processor 1104, causes the processing system 1114 to perform the various functions described above for any particular device. The computer-readable medium / memory 1106 may also be used to store data manipulated by the processor 1104 when executing software. The processing system 1114 further includes at least one of the components 1004, 1006, 1008, 1010, 1012, 1014, 1016, 1018. These components may be software components operating within the processor 1104 and residing / stored on the computer-readable medium / memory 1106, one or more hardware components coupled to the processor 1104, or some combination thereof. The processing system 1114 may be a component of the UE 350 and may include the memory 360 and / or at least one of the TX processor 368, the RX processor 356, and the controller / processor 359. Alternatively, the processing system 1114 may be the entire UE (e.g., see the UE 350 in FIG. 3).

[0099] In one configuration, an apparatus 1002 / 1002′ for wireless communication includes means for determining, based on a rule, a default uplink transmission beam for transmitting an uplink transmission when no uplink transmission beam is configured by a base station for the uplink transmission, and means for transmitting the uplink transmission to the base station on the default uplink transmission beam. In another aspect, the apparatus 1002 / 1002′ may include means for determining that a default uplink transmission beam corresponds to a beam used to receive a downlink transmission, and parameters for the default uplink transmission beam may correspond to that beam. In another aspect, the apparatus 1002 / 1002′ may include means for receiving a downlink shared channel from a base station, and the means for determining, based on a rule, a default uplink transmission beam may be configured to determine the default uplink transmission beam based on a beam used to receive a downlink transmission. In another aspect, the apparatus 1002 / 1002′ may include means for selecting a beam corresponding to a smallest TCI state identifier of an activated TCI state associated with the downlink shared channel. In another aspect, the apparatus 1002 / 1002′ may include means for selecting a beam corresponding to a TCI state identifier of a TCI state associated with a downlink shared channel. In another aspect, the apparatus 1002 / 1002′ may include means for selecting a beam corresponding to a downlink shared channel beam last successfully received after a threshold period. In another aspect, the apparatus 1002 / 1002′ may include means for selecting a beam associated with a CORESET. In another aspect, the apparatus 1002 / 1002′ may include means for receiving a CORESET identifier for the CORESET via at least one of RRC signaling or MAC-CE. In another aspect, the apparatus 1002 / 1002′ may include means for selecting a beam indicated in the DCI.In another aspect, the apparatus 1002 / 1002′ may include means for determining a default uplink transmission beam for each TRP of the plurality of TRPs based on a corresponding beam used to receive downlink transmissions. In another aspect, the apparatus 1002 / 1002′ may include means for determining a first default uplink transmission beam for transmitting an uplink control channel, means for determining a second default uplink transmission beam for transmitting an SRS, and / or means for determining a third default uplink transmission beam for transmitting an SR. In another aspect, the apparatus 1002 / 1002′ may include means for receiving default uplink spatial relationship information from a base station for determining the default uplink transmission beam, and means for determining a default uplink transmission beam for subsequent plurality of uplink transmissions based on the default uplink spatial relationship information. In another aspect, the apparatus 1002 / 1002′ may include means for receiving the default uplink spatial relationship information via at least one of RRC signaling, MAC-CE signaling, and DCI signaling.

[0100] The aforementioned means may be one or more of the aforementioned components of apparatus 1002 and / or processing system 1114 of apparatus 1002′ configured to perform the functions recited by the aforementioned means. As described above, processing system 1114 may include TX processor 368, RX processor 356, and controller / processor 359. Thus, in one configuration, the aforementioned means may be TX processor 368, RX processor 356, and controller / processor 359 configured to perform the functions recited by the aforementioned means.

[0101] 12 is a flowchart 1200 of a method of wireless communication. The method may be performed by a base station (e.g., 102 / 180, base station 310, base station 402, base station 1050, device 1302 / 1302′, processing system 1414, which may include memory 376, may be the entire base station 310, or may be a component of the base station 310, such as the TX processor 316, the RX processor 370, and / or the controller / processor 375). Optional aspects are illustrated using dashed lines. The example flowchart 1200 of FIG. 12 facilitates enabling a base station to perform fast and efficient uplink beam selection by a UE for transmitting an uplink transmission (e.g., when no uplink beam is configured for the uplink transmission), which may result in improved cell coverage, for example, by reducing overhead signaling between the base station and the UE.

[0102] At 1202, the base station transmits a downlink transmission to the UE on a downlink beam, e.g., as described with respect to downlink transmission 410 of FIG. 4. For example, a transmitting component 1306 may facilitate transmitting the downlink transmission. In some examples, the downlink transmission may comprise one or more of a downlink shared channel, a CORESET, DCI signaling, and / or default spatial relationship information. In some examples, the downlink transmission may be transmitted via RRC signaling or MAC-CE signaling.

[0103] At 1204, the base station may select a beam to monitor to receive the uplink transmission, e.g., as described with respect to 440 of FIG. 4. For example, a beam selection component 1308 may facilitate the selection of a beam to monitor to receive the uplink transmission. In some examples, parameters of the selected beam may correspond to a downlink beam.

[0104] In some examples, the downlink transmission may be a downlink shared channel, and the base station may select a beam based on parameters associated with the downlink shared channel. For example, at 1206, the base station may select a beam corresponding to a minimum TCI state identifier of an activated TCI state associated with the downlink shared channel. For example, the downlink shared channel processing component 1310 may facilitate the selection of a beam corresponding to a minimum TCI state identifier of an activated TCI state associated with the downlink shared channel.

[0105] In some examples, the base station may select a beam corresponding to a particular TCI state identifier of a TCI state associated with the downlink shared channel at 1208. For example, the downlink shared channel processing component 1310 may facilitate the selection of a beam corresponding to a particular TCI state identifier of a TCI state associated with the downlink shared channel.

[0106] In some examples, the base station may select 1210 a beam corresponding to the last successfully received downlink shared channel beam after a threshold period. For example, downlink shared channel processing component 1310 may facilitate selection of the beam corresponding to the last successfully received downlink shared channel beam after a threshold period.

[0107] In some examples, the downlink transmission may include a CORESET identifier associated with a particular CORESET, and the base station may select a beam based on the particular CORESET. For example, at 1212, the base station may select a beam corresponding to a beam associated with the particular CORESET. For example, the CORESET processing component 1312 may facilitate the selection of the beam corresponding to the beam associated with the particular CORESET. In some examples, the particular CORESET includes the smallest CORESET identifier among the slots last monitored by the UE. In some examples, the particular CORESET includes the smallest CORESET identifier among a set of configured CORESETs. In some examples, the base station may transmit the CORESET identifier via at least one of RRC signaling or MAC-CE signaling.

[0108] In some examples, the downlink transmission may include DCI signaling, and the base station may select a beam based on the DCI signaling. For example, at 1214, the base station may select a beam indicated in the DCI signaling. For example, the DCI processing component 1314 may facilitate the selection of a beam based on the DCI signaling.

[0109] In some examples, the base station may select respective beams for corresponding uplink transmissions at 1216. For example, the beam selection component 1308 may facilitate selection of a first beam for receiving an uplink control channel, a second beam for receiving an SRS, and a third beam for receiving an SR. In some examples, two or more of the beams may be the same beam.

[0110] In some examples, the downlink transmission may comprise default uplink spatial relationship information, and the base station may select a beam to monitor based on the default uplink spatial relationship information. For example, at 1218, the base station may select a beam for receiving the multiple uplink transmissions based on the default uplink spatial relationship information. For example, spatial relationship information processing component 1316 may facilitate the selection of a beam based on the default uplink spatial relationship information.

[0111] At 1220, the base station receives an uplink transmission from the UE on a default uplink transmit beam when an uplink transmit beam is not configured by the base station for the uplink transmission, e.g., as described with respect to uplink transmission 450 and beam 454 of FIG. 4 . For example, receiving component 1304 may receive the uplink transmission. As described above, to reduce signaling overhead, the spatial relationship information for the uplink transmission (e.g., an uplink transmit beam) may be an optional parameter and thus may not be explicitly configured by the base station for the UE. In the absence of explicit configuration of the spatial relationship information from the base station (e.g., when an uplink transmit beam is not configured by the base station), the UE may implicitly determine a default uplink transmit beam for transmitting the uplink transmission.

[0112] 13 is a conceptual data flow diagram 1300 illustrating data flow between different means / components in an exemplary apparatus 1302 in communication with a UE 1350. The apparatus 1302 may be a base station or a component of a base station. The apparatus 1302 includes a receiving component 1304, a transmitting component 1306, a beam selection component 1308, a downlink shared channel processing component 1310, a CORESET processing component 1312, a DCI processing component 1314, and a spatial relationship information processing component 1316. The UE 1350 may include the same or similar components as shown with respect to the UE 104 of FIG. 1, the UE 350 of FIG. 3, the UE 404 of FIG. 4, and / or the apparatus 1002 / 1002′ of FIG. 10 / FIG. 11.

[0113] The receiving component 1304 may be configured to receive various types of signals / messages and / or other information from other devices, including, for example, the UE 1350. The messages / information may be received via the receiving component 1304 and provided to one or more components of the apparatus 1302 for further processing and / or use in performing various operations. For example, the receiving component 1304 may be configured to receive uplink transmissions transmitted on a default uplink transmit beam when no uplink transmit beam has been configured by the base station for the uplink transmission (e.g., as described with respect to 1220).

[0114] The transmitting component 1306 may be configured to transmit various types of signals / messages and / or other information to other devices, including, for example, the UE 1350. For example, the transmitting component 1306 may be configured to transmit a downlink transmission on a downlink beam used to transmit the downlink transmission (e.g., as described with respect to 1202), transmit a downlink shared channel, transmit a CORESET identifier via RRC signaling or MAC-CE signaling, transmit DCI signaling, and / or transmit default uplink spatial relationship information via RRC signaling, MAC-CE signaling, or DCI signaling.

[0115] The beam selection component 1308 may be configured to select beams to monitor to receive uplink transmissions (e.g., as described with respect to 1204 and / or 1216) and / or to select respective beams for corresponding uplink transmissions.

[0116] The downlink shared channel processing component 1310 may be configured to select a beam corresponding to the smallest TCI state identifier of the activated TCI states associated with the downlink shared channel (e.g., as described with respect to 1206, 1208, and / or 1210), select a beam corresponding to a particular TCI state identifier of the TCI state associated with the downlink shared channel, and / or select a beam corresponding to the last successfully received downlink shared channel beam after a threshold period.

[0117] The CORESET processing component 1312 may be configured to select beams corresponding to beams associated with a particular CORESET (eg, as described with respect to 1212).

[0118] The DCI processing component 1314 may be configured to select a beam indicated in the DCI signaling (e.g., as described with respect to 1214).

[0119] The spatial relationship information processing component 1316 may be configured to select a beam for receiving multiple uplink transmissions based on the default uplink spatial relationship information (e.g., as described with respect to 1218).

[0120] The apparatus may include additional components that perform each of the blocks of the algorithm in the flowchart of Figure 12 described above. Thus, each block in the flowchart of Figure 12 described above may be performed by a component, and the apparatus may include one or more of those components. The components may be one or more hardware components specifically configured to perform the described process / algorithm, implemented by a processor configured to perform the described process / algorithm, stored in a computer-readable medium for implementation by a processor, or some combination thereof.

[0121] 14 is a diagram 1400 illustrating an example of a hardware implementation of an apparatus 1302′ utilizing a processing system 1414. The processing system 1414 may be implemented using a bus architecture, represented generally by bus 1424. The bus 1424 may include any number of interconnected buses and bridges, depending on the specific application and overall design constraints of the processing system 1414. The bus 1424 couples various circuits together, including the processor 1404, components 1304, 1306, 1308, 1310, 1312, 1314, 1316, and one or more processors and / or hardware components represented by computer-readable medium / memory 1406. The bus 1424 may also couple various other circuits, such as timing sources, peripheral devices, voltage regulators, and power management circuits, which are well known in the art and therefore will not be described further.

[0122] The processing system 1414 may be coupled to a transceiver 1410. The transceiver 1410 is coupled to one or more antennas 1420. The transceiver 1410 provides a means for communicating with various other devices over a transmission medium. The transceiver 1410 receives signals from one or more antennas 1420, extracts information from the received signals, and provides the extracted information to the processing system 1414, particularly to the receiving component 1304. In addition, the transceiver 1410 receives information from the processing system 1414, particularly from the transmitting component 1306, and generates signals to be applied to the one or more antennas 1420 based on the received information. The processing system 1414 includes a processor 1404 coupled to a computer-readable medium / memory 1406. The processor 1404 is responsible for general processing, including the execution of software stored on the computer-readable medium / memory 1406. The software, when executed by the processor 1404, causes the processing system 1414 to perform the various functions described above for any particular device. The computer-readable medium / memory 1406 may also be used to store data manipulated by the processor 1404 when executing software. The processing system 1414 further includes at least one of the components 1304, 1306, 1308, 1310, 1312, 1314, 1316. These components may be software components operating within the processor 1404 and residing / stored on the computer-readable medium / memory 1406, one or more hardware components coupled to the processor 1404, or some combination thereof. The processing system 1414 may be a component of the base station 310 and may include the memory 376 and / or at least one of the TX processor 316, the RX processor 370, and the controller / processor 375. Alternatively, the processing system 1414 may be the entire base station (e.g., see base station 310 of FIG. 3).

[0123] In one configuration, an apparatus 1302 / 1302′ for wireless communication includes means for transmitting a downlink transmission to a UE on a downlink beam used to transmit the downlink transmission, and means for receiving an uplink transmission from the UE on a default uplink transmission beam when no uplink transmission beam is configured by the base station for the uplink transmission. In another aspect, the apparatus 1302 / 1302′ may include means for selecting a beam to monitor to receive an uplink transmission, where parameters of the selected beam correspond to the downlink beam. In another aspect, the apparatus 1302 / 1302′ may include means for selecting a beam corresponding to the smallest TCI state identifier of an activated TCI state associated with a downlink shared channel. In another aspect, the apparatus 1302 / 1302′ may include means for selecting a beam corresponding to a TCI state identifier of a TCI state associated with a downlink shared channel. In another aspect, the apparatus 1302 / 1302′ may include means for selecting a beam corresponding to the last successfully received downlink shared channel beam after a threshold period. In another aspect, the apparatus 1302 / 1302′ may include means for selecting a beam to monitor to receive uplink transmissions based on a beam associated with the CORESET. In another aspect, the apparatus 1302 / 1302′ may include means for transmitting a CORESET identifier for the CORESET via at least one of RRC or MAC-CE. In another aspect, the apparatus 1302 / 1302′ may include means for selecting a beam to monitor to receive uplink transmissions based on a beam indicated in the DCI. In another aspect, the apparatus 1302 / 1302′ may include means for communicating using a plurality of TRPs, where, for each TRP, selection of a beam to monitor to receive uplink transmissions is based on a corresponding downlink beam. In another aspect, the apparatus 1302 / 1302′ may include means for selecting a first beam to receive an uplink control channel and a second beam to receive an SRS.In another aspect, the apparatus 1302 / 1302′ may include means for selecting, based on the default uplink spatial relationship information, a beam to monitor for receiving a plurality of uplink transmissions. In another aspect, the apparatus 1302 / 1302′ may include means for transmitting the default uplink spatial relationship information to the UE via at least one of RRC signaling, MAC-CE signaling, and DCI signaling.

[0124] The aforementioned means may be one or more of the aforementioned components of the apparatus 1302 and / or the processing system 1414 of the apparatus 1302′ configured to perform the functions recited by the aforementioned means. As described above, the processing system 1414 may include the TX processor 316, the RX processor 370, and the controller / processor 375. Thus, in one configuration, the aforementioned means may be the TX processor 316, the RX processor 370, and the controller / processor 375 configured to perform the functions recited by the aforementioned means.

[0125] It should be understood that the specific order or hierarchy of blocks in the disclosed processes / flowcharts is an indication of example approaches. Based on design preferences, it should be understood that the specific order or hierarchy of blocks in the processes / flowcharts may be rearranged. Further, some blocks may be combined or omitted. The accompanying method claims present elements of the various blocks in an example order and are not limited to the specific order or hierarchy presented.

[0126] The following examples are illustrative only and may be combined without limitation with other embodiments or aspects of the teachings described herein.

[0127] Example 1 is a method of wireless communication in a UE, the method comprising: when an uplink transmission beam is not configured by a base station for the uplink transmission, determining a default uplink transmission beam for transmitting the uplink transmission based on a rule; and transmitting the uplink transmission to the base station on the default uplink transmission beam.

[0128] In Example 2, the method of Example 1 further includes the UE determining that a default uplink transmit beam corresponds to a beam used to receive downlink transmissions, and parameters for the default uplink transmit beam correspond to that beam.

[0129] In Example 3, the method of either Example 1 or Example 2 further includes receiving a downlink shared channel from the base station, and determining the default uplink transmission beam based on the rule includes determining the default uplink transmission beam based on a beam used to receive the downlink transmission.

[0130] In Example 4, the method of any of Examples 1 to 3 further includes: determining the default uplink transmission beam based on the beam used to receive the downlink transmission includes selecting a beam corresponding to the smallest TCI state identifier of the activated TCI states associated with the downlink shared channel.

[0131] In Example 5, the method of any of Examples 1 to 4 further includes: determining the default uplink transmission beam based on a beam used to receive the downlink transmission includes selecting a beam corresponding to a TCI state identifier of a TCI state associated with the downlink shared channel.

[0132] In Example 6, the method of any of Examples 1 to 5 further includes, wherein determining the default uplink transmission beam based on the beam used to receive the downlink transmission includes selecting a beam corresponding to the last successfully received downlink shared channel beam after a threshold period.

[0133] In Example 7, the method of any of Examples 1 to 6 further includes: determining the default uplink transmit beam based on the rule includes selecting a beam associated with a control resource set (CORESET) having a smallest CORESET identifier.

[0134] In Example 8, the method of any of Examples 1-7 further includes: the CORESET including the smallest CORESET identifier among the slots last monitored by the UE.

[0135] In Example 9, the method of any of Examples 1-8 further includes the CORESET including the smallest CORESET identifier of the set of configured CORESETs.

[0136] In Example 10, the method of any of Examples 1-9 further includes receiving, at the UE, a CORESET identifier for the CORESET via at least one of RRC or MAC-CE.

[0137] In Example 11, the method of any of Examples 1-10 further includes: determining the default uplink transmit beam based on the rule includes selecting a beam indicated in the DCI.

[0138] In Example 12, the method of any of Examples 1 to 11 further includes the UE communicating with multiple TRPs, and for each TRP, determining the default uplink transmit beam is based on a corresponding beam used to receive downlink transmissions.

[0139] In Example 13, the method of any of Examples 1-12 further includes the uplink transmission comprising at least one of an uplink control channel, an SRS, or an SR.

[0140] In Example 14, the method of any of Examples 1 to 13 further includes determining a default uplink transmission beam for transmitting an uplink transmission comprising determining a first default uplink transmission beam for transmitting an uplink control channel, and the example further includes determining a second default uplink transmission beam for transmitting an SRS.

[0141] In Example 15, the method of any of Examples 1-14 further includes the first default uplink transmit beam being the same as the second default uplink transmit beam.

[0142] In Example 16, the method of any of Examples 1 to 15 further includes receiving default uplink spatial relationship information from a base station for determining a default uplink transmission beam, and determining a default uplink transmission beam for a plurality of subsequent uplink transmissions based on the default uplink spatial relationship information.

[0143] In Example 17, the method of any of Examples 1 to 16 further includes receiving the default uplink spatial relationship information via at least one of RRC signaling, MAC-CE signaling, and DCI signaling.

[0144] Example 18 is a system or device including means for carrying out the method or realizing the device of any of Examples 1-17.

[0145] Example 19 is a device including one or more processors and one or more memories in electronic communication with the one or more processors that store instructions, the instructions being executable by the one or more processors to cause the system or apparatus to perform the method of any of Examples 1-17.

[0146] Example 20 is a non-transitory computer-readable medium storing instructions, the instructions executable by one or more processors to cause the one or more processors to perform the method of any of Examples 1-17.

[0147] Example 21 is a method of wireless communication in a base station, the method comprising: transmitting a downlink transmission to a UE on a downlink beam; and, when an uplink transmission beam is not configured by the base station for the uplink transmission, receiving an uplink transmission from the UE using a default uplink transmission beam.

[0148] In Example 22, the method of Example 21 further includes selecting a beam to monitor to receive an uplink transmission, wherein parameters of the selected beam correspond to the downlink beam.

[0149] In Example 23, the method of either Example 21 or Example 22 further includes: the downlink transmission is a downlink shared channel; and the selected beam corresponds to a minimum TCI state identifier of an activated TCI state associated with the downlink shared channel.

[0150] In Example 24, the method of any of Examples 21-23 further includes: the downlink transmission is a downlink shared channel; and the selected beam corresponds to a TCI state identifier of a TCI state associated with the downlink shared channel.

[0151] In Example 25, the method of any of Examples 21 to 24 further includes: the downlink transmission is a downlink shared channel; and the selected beam corresponds to the last successfully received downlink shared channel beam after a threshold period.

[0152] In Example 26, the method of any of Examples 21 to 25 further includes: selecting a beam to monitor to receive an uplink transmission based on a beam associated with a control resource set (CORESET) having a smallest CORESET identifier.

[0153] In Example 27, the method of any of Examples 21-26 further includes: the CORESET includes the smallest CORESET identifier among the slots last monitored by the UE.

[0154] In Example 28, the method of any of Examples 21-27 further includes the CORESET including a minimum CORESET identifier from the set of configured CORESETs.

[0155] In Example 29, the method of any of Examples 21 to 28 further includes transmitting a CORESET identifier for the CORESET via at least one of the RRC or MAC-CE.

[0156] In Example 30, the method of any of Examples 21-29 further includes: selecting a beam to monitor to receive an uplink transmission based on a beam indicated in the DCI.

[0157] In Example 31, the method of any of Examples 21 to 30 further includes the base station communicating using multiple TRPs, and for each TRP, the selection of a beam to monitor to receive uplink transmissions is based on the corresponding downlink beam.

[0158] In Example 32, the method of any of Examples 21-31 further includes: the uplink transmission comprises at least one of an uplink control channel, an SRS, or an SR.

[0159] In Example 33, the method of any of Examples 21 to 32 further includes selecting a beam to monitor to receive an uplink transmission includes selecting a first beam for receiving an uplink control channel, and the example further includes selecting a second beam for receiving an SRS.

[0160] In Example 34, the method of any of Examples 21-33 further includes the first beam being the same as the second beam.

[0161] In Example 35, the method of any of Examples 21 to 34 further includes the downlink transmission including default uplink spatial relationship information for determining a default uplink transmission beam, and the example further includes selecting, based on the default uplink spatial relationship information, a beam to monitor for receiving the multiple uplink transmissions.

[0162] In Example 36, the method of any of Examples 21 to 35 further includes transmitting the default uplink spatial relationship information to the UE via at least one of RRC signaling, MAC-CE signaling, and DCI signaling.

[0163] Example 37 is a system or device including means for carrying out the method or realizing the device of any of Examples 21-36.

[0164] Example 38 is a device including one or more processors and one or more memories in electronic communication with the one or more processors that store instructions, the instructions being executable by the one or more processors to cause the system or apparatus to perform the method of any of Examples 21-36.

[0165] Example 39 is a non-transitory computer-readable medium storing instructions, the instructions being executable by one or more processors to cause the one or more processors to perform the method of any of Examples 21-36.

[0166] The foregoing description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects. Accordingly, the claims are not limited to the aspects shown herein but are to be accorded the widest scope consistent with the claim language, and references to elements in the singular do not mean "one and only one," unless so expressly stated, but rather "one or more." The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any aspect described herein as "exemplary" should not necessarily be construed as preferred or advantageous over other aspects. Unless expressly stated otherwise, the term "some" refers to one or more. Combinations such as "at least one of A, B, or C," "one or more of A, B, or C," "at least one of A, B, and C," "one or more of A, B, and C," and "A, B, C, or any combination thereof" include any combination of A, B, and / or C, and may include multiple As, multiple Bs, or multiple Cs. Specifically, combinations such as "at least one of A, B, or C," "one or more of A, B, or C," "at least one of A, B, and C," "one or more of A, B, and C," and "A, B, C, or any combination thereof" may be A only, B only, C only, A and B, A and C, B and C, or A and B and C, and any such combination may include one or more members of A, B, or C. All structural and functional equivalents to the elements of the various embodiments described throughout this disclosure that are known, or that later become known, to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is made available to the public, regardless of whether such disclosure is expressly recited in the claims.Words such as "module," "mechanism," "element," and "device" may not be substitutes for the word "means." Accordingly, no claim element should be construed as a means-plus-function unless the element is expressly recited using the phrase "means for." [Explanation of symbols]

[0167] 102 Base station 104UE 110 Geographic Coverage Areas 120 Communication Links 132 First Backhaul Link 134 Third Backhaul Link 150 Wi-Fi access points 152 Wi-Fi stations 154 communication links 158 Inter-Device Communication Links 160 EPC 162 MME 164 other MMEs 166 Serving Gateway 168 MBMS GW 170 BM-SC 172 PDN Gateway 174 HSS 176 IP Services 180 gNB, base station 182 Beamforming 184 Second Backhaul Link 190 Core Network 192 AMF 193 Other AMF 194 SMF 195 UPF 196 UDM 197 IP Services 198 UE Spatial Relation Components 199 Base Station Transmission Configuration Display Component 310 base station 316 TX Processor 318RX receiver 318TX Transmitter 320 Antenna 350 UE 352 Antenna 354RX receiver 354TX Transmitter 356 RX processor 358 Channel Estimator 359 Controller / Processor 360 memory 368 TX Processor 370 RX processor 374 Channel Estimator 375 Controller / Processor 376 memory 400 Wireless Communications 402 Base Station 404 UE 410 Downlink Transmission 450 uplink transmit 1002 Equipment 1004 Receiving Component 1006 Sending Component 1008 TCI State Identifier Component 1010 Shared Channel Beam Components 1012 CORESET Processing Components 1014 DCI Processing Components 1016 Spatial Relationship Information Processing Component 1018 Default Uplink Transmit Beam Decision Component 1050 base station 1104 processor 1106 Computer-readable medium / memory 1110 transceiver 1114 Processing System 1120 Antenna 1124 Bus 1302 Equipment 1304 Receiving Component 1306 Sending Component 1308 Beam Selection Component 1310 Downlink Shared Channel Processing Component 1312 CORESET Processing Component 1314 DCI Processing Components 1316 Spatial Relationship Information Processing Component 1350 UE 1404 processor 1406 Computer-readable medium / memory 1410 Transceiver 1414 Processing System 1420 Antenna 1424 Bus

Claims

1. 1. A method of wireless communication in a user equipment (UE), comprising: determining a default uplink transmit beam for transmitting an uplink transmission, determining the default uplink transmission beam includes selecting an uplink beam corresponding to a minimum transmission configuration indication (TCI) state identifier of an activated TCI state associated with a downlink shared channel; transmitting the uplink transmission on the default uplink transmit beam to a base station; A method comprising:

2. The method of claim 1 , wherein the uplink transmission comprises a sounding reference signal (SRS).

3. determining a default uplink transmission beam for transmitting the uplink transmission comprises determining a first default uplink transmission beam for transmitting an uplink control channel, the method comprising: The method of claim 2 , further comprising determining a second default uplink transmit beam for transmitting the SRS.

4. The method described in claim 3, wherein the first default uplink transmission beam is the same uplink beam as the second default uplink transmission beam.

5. The method described in claim 1, wherein parameters for the default uplink transmission beam correspond to a beam for the downlink shared channel.

6. 2. The method of claim 1, wherein the UE communicates with multiple transmission / reception points (TRPs), and for each TRP, determining the default uplink transmission beam is based on a corresponding beam used to receive a respective downlink shared channel.

7. The UE determining the default uplink transmission beam based on the absence of a configuration of an uplink transmission beam by the base station for the uplink transmission; The method of claim 1 , wherein the absence of configuration of the uplink transmit beam comprises the absence of explicit configuration of spatial relationship information from the base station.

8. An apparatus for wireless communication in a user equipment (UE), comprising: Memory and at least one processor coupled to the memory; wherein the at least one processor: determining a default uplink transmit beam for transmitting an uplink transmission, determining, wherein the determining of the default uplink transmission beam includes selecting an uplink beam corresponding to a minimum transmission configuration indication (TCI) state identifier of activated TCI states associated with a downlink shared channel; transmitting the uplink transmission on the default uplink transmit beam to a base station; An apparatus configured to:

9. The device of claim 8, wherein the uplink transmission comprises a sounding reference signal (SRS).

10. The at least one processor: determining a first default uplink transmit beam for transmitting an uplink control channel; determining a second default uplink transmit beam for transmitting the SRS; The apparatus of claim 9 , further configured to:

11. The device described in claim 10, wherein the first default uplink transmission beam is the same uplink beam as the second default uplink transmission beam.

12. The device described in claim 8, wherein parameters for the default uplink transmission beam correspond to a beam for the downlink shared channel.

13. The UE is in communication with multiple transmission / reception points (TRPs); 10. The apparatus of claim 8, wherein the at least one processor is configured to determine the default uplink transmission beam for each TRP based on a corresponding beam used to receive a respective downlink shared channel.

14. The UE determining the default uplink transmission beam based on the absence of a configuration of an uplink transmission beam by the base station for the uplink transmission; 10. The apparatus of claim 8, wherein the absence of configuration of the uplink transmit beam comprises the absence of explicit configuration of spatial relationship information from the base station.

15. 1. A method of wireless communication in a base station, comprising: selecting a beam to monitor to receive an uplink transmission based on the downlink beam; the selected beam to monitor corresponds to a minimum transmission configuration indication (TCI) state identifier of activated TCI states associated with a downlink shared channel; receiving the uplink transmission from a user equipment (UE) on the selected beam; A method comprising:

16. 16. The method of claim 15, wherein the uplink transmission comprises a sounding reference signal (SRS).

17. wherein selecting a beam to monitor to receive an uplink transmission includes selecting a first beam to monitor to receive an uplink control channel, the method comprising: The method of claim 16 , further comprising selecting a second beam to monitor to receive the SRS.

18. 18. The method of claim 17, wherein the first beam is the same beam as the second beam.

19. The method described in claim 15, wherein the parameters of the selected beam to monitor correspond to the downlink beam for the downlink shared channel.

20. 16. The method of claim 15, wherein the base station communicates using multiple transmission / reception points (TRPs), and for each TRP, selecting the beam to monitor to receive the uplink transmission is based on a corresponding downlink beam.

21. The base station receiving the uplink transmission on the selected beam based on the absence of a configuration of an uplink transmission beam by the base station for the uplink transmission; 16. The method of claim 15, wherein the absence of configuration of the uplink transmit beam comprises the absence of explicit configuration of spatial relationship information from the base station.

22. 1. An apparatus for wireless communication at a base station, comprising: Memory and at least one processor coupled to the memory; wherein the at least one processor: selecting a beam to monitor to receive an uplink transmission based on the downlink beam; selecting, wherein the selected beam to monitor corresponds to a minimum transmission configuration indication (TCI) state identifier of activated TCI states associated with a downlink shared channel; receiving the uplink transmission from a user equipment (UE) on the selected beam; An apparatus configured to:

23. The apparatus of claim 22, wherein the uplink transmission comprises a sounding reference signal (SRS).

24. The at least one processor: selecting a first beam to monitor to receive an uplink control channel; selecting a second beam to monitor to receive the SRS; 24. The apparatus of claim 23, further configured to:

25. The apparatus of claim 24, wherein the first beam is the same beam as the second beam.

26. The device described in Claim 22, wherein the parameters of the selected beam to monitor correspond to the downlink beam for the downlink shared channel.

27. The base station communicates using a plurality of transmission / reception points (TRPs); 23. The apparatus of claim 22, wherein the at least one processor is configured to select, for each TRP based on a corresponding downlink beam, the beam to monitor to receive the uplink transmission.

28. The at least one processor is configured to receive the uplink transmission on the selected beam based on the absence of configuration of an uplink transmission beam by the base station for the uplink transmission; 23. The apparatus of claim 22, wherein the absence of configuration of the uplink transmit beam comprises the absence of explicit configuration of spatial relationship information from the base station.

Images