WO2023225883A1

WO2023225883A1 - Unified transmission configuration indicator state activation for sounding reference signals

Info

Publication number: WO2023225883A1
Application number: PCT/CN2022/094842
Authority: WO
Inventors: Fang Yuan; Yan Zhou; Tao Luo
Original assignee: Qualcomm Incorporated
Priority date: 2022-05-25
Filing date: 2022-05-25
Publication date: 2023-11-30

Abstract

Certain aspects of the present disclosure provide a method for wireless communications at a user equipment (UE) generally including obtaining first signaling configuring the UE with at least one of a sounding reference signal (SRS) resource set or one or more unified Transmission Configuration Indicator (TCI) states for a SRS, obtaining second signaling activating or deactivating at least one of the unified TCI states for at least one SRS resource in the SRS resource set, and outputting, for transmission, the SRS via the SRS resource in accordance with the activated or deactivated unified TCI state.

Description

UNIFIED TRANSMISSION CONFIGURATION INDICATOR STATE ACTIVATION FOR SOUNDING REFERENCE SIGNALS

BACKGROUND

Field of the Disclosure

Aspects of the present disclosure relate to wireless communications, and more particularly, to techniques for activating unified Transmission Configuration Indicator (TCI) states for sounding reference signal (SRS) transmissions.

Description of Related Art

Wireless communications systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, broadcasts, or other similar types of services. These wireless communications systems may employ multiple-access technologies capable of supporting communications with multiple users by sharing available wireless communications system resources with those users.

Although wireless communications systems have made great technological advancements over many years, challenges still exist. For example, complex and dynamic environments can still attenuate or block signals between wireless transmitters and wireless receivers. Accordingly, there is a continuous desire to improve the technical performance of wireless communications systems, including, for example: improving speed and data carrying capacity of communications, improving efficiency of the use of shared communications mediums, reducing power used by transmitters and receivers while performing communications, improving reliability of wireless communications, avoiding redundant transmissions and/or receptions and related processing, improving the coverage area of wireless communications, increasing the number and types of devices that can access wireless communications systems, increasing the ability for different types of devices to intercommunicate, increasing the number and type of wireless communications mediums available for use, and the like. Consequently, there exists a need for further improvements in wireless communications systems to overcome the aforementioned technical challenges and others.

SUMMARY

One aspect provides a method of wireless communications by a user equipment (UE) . The method includes obtaining first signaling configuring the UE with at least one of a sounding reference signal (SRS) resource set or one or more unified Transmission Configuration Indicator (TCI) states for a SRS; obtaining second signaling activating or deactivating at least one of the unified TCI states for at least one SRS resource in the SRS resource set; and outputting, for transmission, the SRS via the SRS resource in accordance with the activated or deactivated unified TCI state.

Another aspect provides a method of wireless communications by a network entity. The method includes outputting, for transmission, first signaling configuring a UE with at least one of a SRS resource set or one or more unified TCI states for a SRS; outputting, for transmission, second signaling activating or deactivating at least one of the unified TCI states for at least one SRS resource in the SRS resource set; and monitoring the SRS resource for SRS transmitted in accordance with the activated or deactivated unified TCI state.

Other aspects provide: an apparatus operable, configured, or otherwise adapted to perform any one or more of the aforementioned methods and/or those described elsewhere herein; a non-transitory, computer-readable media comprising instructions that, when executed by a processor of an apparatus, cause the apparatus to perform the aforementioned methods as well as those described elsewhere herein; a computer program product embodied on a computer-readable storage medium comprising code for performing the aforementioned methods as well as those described elsewhere herein; and/or an apparatus comprising means for performing the aforementioned methods as well as those described elsewhere herein. By way of example, an apparatus may comprise a processing system, a device with a processing system, or processing systems cooperating over one or more networks.

The following description and the appended figures set forth certain features for purposes of illustration.

BRIEF DESCRIPTION OF DRAWINGS

The appended figures depict certain features of the various aspects described herein and are not to be considered limiting of the scope of this disclosure.

FIG. 1 depicts an example wireless communications network.

FIG. 2 depicts an example disaggregated base station architecture.

FIG. 3 depicts aspects of an example base station and an example user equipment.

FIGS. 4A, 4B, 4C, and 4D depict various example aspects of data structures for a wireless communications network.

FIG. 5 is a call flow diagram illustrating an example of codebook based UL transmission, in accordance with certain aspects of the present disclosure.

FIG. 6 is a call flow diagram illustrating an example of non-codebook based UL transmission, in accordance with certain aspects of the present disclosure.

FIG. 7 illustrates an example joint TCI state configuration.

FIGs. 8-10 illustrate examples of medium access control (MAC) control element (CE) formats for activating Transmission Configuration Indicator (TCI) states.

FIG. 11 depicts a call flow diagram for PUSCH transmissions, in accordance with certain aspects of the present disclosure.

FIGs. 12A and 12B illustrate examples of a MAC CE format for activating TCI state for SRS, in accordance with certain aspects of the present disclosure.

FIGs. 13A and 13B illustrate examples of a MAC CE format for activating TCI state for SRS, in accordance with certain aspects of the present disclosure.

FIGs. 14A and 14B illustrate examples of a MAC CE format for activating TCI state for SRS, in accordance with certain aspects of the present disclosure.

FIGs. 15A and 15B illustrate examples of a MAC CE format for activating TCI state for SRS, in accordance with certain aspects of the present disclosure.

FIG. 16 depicts a method for wireless communications.

FIG. 17 depicts a method for wireless communications.

FIG. 18 depicts aspects of an example communications device.

FIG. 19 depicts aspects of an example communications device.

DETAILED DESCRIPTION

Aspects of the present disclosure provide apparatuses, methods, processing systems, and computer-readable mediums for activating unified Transmission Configuration Indicator (TCI) states for sounding reference signal (SRS) transmissions.

In some systems (e.g., NR Release 15/16) , a user equipment (UE) is indicated with a directional beam to use for certain uplink transmissions, such as semi-persistent (SP) and aperiodic (AP) sounding reference signals. In some cases, a beam for SP or AP SRS may be indicated via activation or deactivation via a medium access control (MAC) control element (CE) . The beam indication may be based on spatial relation information configured for SRS resource sets.

In some systems (e.g., NR Release 17) , spatial information may be specified for multiple channels via unified Transmission Configuration Indicator (TCI) states. Because they apply to multiple channels, unified TCI states may provide an efficient configuration and signaling mechanism. Unfortunately, current MAC CE formats for activating TCI states may not be optimal for activating unified TCI states for SRS. Further, there may be ambiguity in some cases, for example, when a UE is configured with unified TCI states, but there is no explicit indication that the UE should apply the unified TCI states for SRS.

Aspects of the present disclosure, however, provide techniques that may help resolve this potential ambiguity and provide MAC CE formats to activate TCI states for SRS transmissions. The techniques may help indicate an optimal beam for SRS transmissions, which may help improve performance.

Introduction to Wireless Communications Networks

The techniques and methods described herein may be used for various wireless communications networks. While aspects may be described herein using terminology commonly associated with 3G, 4G, and/or 5G wireless technologies, aspects of the present disclosure may likewise be applicable to other communications systems and standards not explicitly mentioned herein.

FIG. 1 depicts an example of a wireless communications network 100, in which aspects described herein may be implemented.

Generally, wireless communications network 100 includes various network entities (alternatively, network elements or network nodes) . A network entity is generally a communications device and/or a communications function performed by a communications device (e.g., a user equipment (UE) , a base station (BS) , a component of a BS, a server, etc. ) . For example, various functions of a network as well as various devices associated with and interacting with a network may be considered network entities. Further, wireless communications network 100 includes terrestrial aspects, such as ground-based network entities (e.g., BSs 102) , and non-terrestrial aspects, such as satellite 140 and aircraft 145, which may include network entities on-board (e.g., one or more BSs) capable of communicating with other network elements (e.g., terrestrial BSs) and user equipments.

In the depicted example, wireless communications network 100 includes BSs 102, UEs 104, and one or more core networks, such as an Evolved Packet Core (EPC) 160 and 5G Core (5GC) network 190, which interoperate to provide communications services over various communications links, including wired and wireless links.

FIG. 1 depicts various example UEs 104, which may more generally include: a cellular phone, smart phone, session initiation protocol (SIP) phone, laptop, personal digital assistant (PDA) , satellite radio, global positioning system, multimedia device, video device, digital audio player, camera, game console, tablet, smart device, wearable device, vehicle, electric meter, gas pump, large or small kitchen appliance, healthcare device, implant, sensor/actuator, display, internet of things (IoT) devices, always on (AON) devices, edge processing devices, or other similar devices. UEs 104 may also be referred to more generally as a mobile device, a wireless device, a wireless communications device, a station, a mobile station, a subscriber station, a mobile subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a remote device, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, and others.

BSs 102 wirelessly communicate with (e.g., transmit signals to or receive signals from) UEs 104 via communications links 120. The communications links 120 between BSs 102 and UEs 104 may include uplink (UL) (also referred to as reverse link) transmissions from a UE 104 to a BS 102 and/or downlink (DL) (also referred to as forward link) transmissions from a BS 102 to a UE 104. The communications links 120 may use multiple-input and multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and/or transmit diversity in various aspects.

BSs 102 may generally include: a NodeB, enhanced NodeB (eNB) , next generation enhanced NodeB (ng-eNB) , next generation NodeB (gNB or gNodeB) , access point, base transceiver station, radio base station, radio transceiver, transceiver function, transmission reception point, and/or others. Each of BSs 102 may provide communications coverage for a respective geographic coverage area 110, which may sometimes be referred to as a cell, and which may overlap in some cases (e.g., small cell 102’ may have a coverage area 110’ that overlaps the coverage area 110 of a macro cell) . A BS may, for example, provide communications coverage for a macro cell (covering relatively large geographic area) , a pico cell (covering relatively smaller geographic area, such as a sports stadium) , a femto cell (relatively smaller geographic area (e.g., a home) ) , and/or other types of cells.

While BSs 102 are depicted in various aspects as unitary communications devices, BSs 102 may be implemented in various configurations. For example, one or more components of a base station may be disaggregated, including a central unit (CU) , one or more distributed units (DUs) , one or more radio units (RUs) , a Near-Real Time (Near-RT) RAN Intelligent Controller (RIC) , or a Non-Real Time (Non-RT) RIC, to name a few examples. In another example, various aspects of a base station may be virtualized. More generally, a base station (e.g., BS 102) may include components that are located at a single physical location or components located at various physical locations. In examples in which a base station includes components that are located at various physical locations, the various components may each perform functions such that, collectively, the various components achieve functionality that is similar to a base station that is located at a single physical location. In some aspects, a base station including components that are located at various physical locations may be referred to as a disaggregated radio access network architecture, such as an Open RAN (O-RAN) or Virtualized RAN (VRAN) architecture. FIG. 2 depicts and describes an example disaggregated base station architecture.

Different BSs 102 within wireless communications network 100 may also be configured to support different radio access technologies, such as 3G, 4G, and/or 5G. For example, BSs 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 first backhaul links 132 (e.g., an S1 interface) . BSs 102 configured for 5G (e.g., 5G NR or Next Generation RAN (NG-RAN) ) may interface with 5GC 190 through second backhaul links 184. BSs 102 may communicate directly or indirectly (e.g., through the EPC 160 or 5GC 190) with each other over third backhaul links 134 (e.g., X2 interface) , which may be wired or wireless.

Wireless communications network 100 may subdivide the electromagnetic spectrum into various classes, bands, channels, or other features. In some aspects, the subdivision is provided based on wavelength and frequency, where frequency may also be referred to as a carrier, a subcarrier, a frequency channel, a tone, or a subband. For example, 3GPP currently defines Frequency Range 1 (FR1) as including 410 MHz –7125 MHz, which is often referred to (interchangeably) as “Sub-6 GHz” . Similarly, 3GPP currently defines Frequency Range 2 (FR2) as including 24,250 MHz –52,600 MHz, which is sometimes referred to (interchangeably) as a “millimeter wave” ( “mmW” or “mmWave” ) . A base station configured to communicate using mmWave/near mmWave radio frequency bands (e.g., a mmWave base station such as BS 180) may utilize beamforming (e.g., 182) with a UE (e.g., 104) to improve path loss and range.

The communications links 120 between BSs 102 and, for example, UEs 104, may be through one or more carriers, which may have different bandwidths (e.g., 5, 10, 15, 20, 100, 400, and/or other MHz) , and which may be aggregated in various aspects. Carriers may or may not be adjacent to each other. Allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated for DL than for UL) .

Communications using higher frequency bands may have higher path loss and a shorter range compared to lower frequency communications. Accordingly, certain base stations (e.g., 180 in FIG. 1) may utilize beamforming 182 with a UE 104 to improve path loss and range. For example, BS 180 and the UE 104 may each include a plurality of antennas, such as antenna elements, antenna panels, and/or antenna arrays to facilitate the beamforming. In some cases, BS 180 may transmit a beamformed signal to UE 104 in one or more transmit directions 182’ . UE 104 may receive the beamformed signal from the BS 180 in one or more receive directions 182” . UE 104 may also transmit a beamformed signal to the BS 180 in one or more transmit directions 182” . BS 180 may also receive the beamformed signal from UE 104 in one or more receive directions 182’ . BS 180 and UE 104 may then perform beam training to determine the best receive and transmit directions for each of BS 180 and UE 104. Notably, the transmit and receive directions for BS 180 may or may not be the same. Similarly, the transmit and receive directions for UE 104 may or may not be the same.

Wireless communications network 100 further includes a Wi-Fi AP 150 in communication with Wi-Fi stations (STAs) 152 via communications links 154 in, for example, a 2.4 GHz and/or 5 GHz unlicensed frequency spectrum.

Certain UEs 104 may communicate with each other using device-to-device (D2D) communications link 158. D2D communications link 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) , a physical sidelink control channel (PSCCH) , and/or a physical sidelink feedback channel (PSFCH) .

EPC 160 may include various functional components, including: 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/or a Packet Data Network (PDN) Gateway 172, such as in the depicted example. MME 162 may be in communication with a Home Subscriber Server (HSS) 174. MME 162 is the control node that processes the signaling between the UEs 104 and the EPC 160. Generally, MME 162 provides bearer and connection management.

Generally, user Internet protocol (IP) packets are transferred through Serving Gateway 166, which itself is connected to PDN Gateway 172. PDN Gateway 172 provides UE IP address allocation as well as other functions. PDN Gateway 172 and the BM-SC 170 are connected to IP Services 176, which may include, for example, the Internet, an intranet, an IP Multimedia Subsystem (IMS) , a Packet Switched (PS) streaming service, and/or other IP services.

BM-SC 170 may provide functions for MBMS user service provisioning and delivery. BM-SC 170 may serve as an entry point for content provider MBMS transmission, may be used to authorize and initiate MBMS Bearer Services within a public land mobile network (PLMN) , and/or may be used to schedule MBMS transmissions. MBMS Gateway 168 may be used to distribute MBMS traffic to the BSs 102 belonging to a Multicast Broadcast Single Frequency Network (MBSFN) area broadcasting a particular service, and/or may be responsible for session management (start/stop) and for collecting eMBMS related charging information.

5GC 190 may include various functional components, including: an Access and Mobility Management Function (AMF) 192, other AMFs 193, a Session Management Function (SMF) 194, and a User Plane Function (UPF) 195. AMF 192 may be in communication with Unified Data Management (UDM) 196.

AMF 192 is a control node that processes signaling between UEs 104 and 5GC 190. AMF 192 provides, for example, quality of service (QoS) flow and session management.

Internet protocol (IP) packets are transferred through UPF 195, which is connected to the IP Services 197, and which provides UE IP address allocation as well as other functions for 5GC 190. IP Services 197 may include, for example, the Internet, an intranet, an IMS, a PS streaming service, and/or other IP services.

In various aspects, a network entity or network node can be implemented as an aggregated base station, as a disaggregated base station, a component of a base station, an integrated access and backhaul (IAB) node, a relay node, a sidelink node, to name a few examples.

FIG. 2 depicts an example disaggregated base station 200 architecture. The disaggregated base station 200 architecture may include one or more central units (CUs) 210 that can communicate directly with a core network 220 via a backhaul link, or indirectly with the core network 220 through one or more disaggregated base station units (such as a Near-Real Time (Near-RT) RAN Intelligent Controller (RIC) 225 via an E2 link, or a Non-Real Time (Non-RT) RIC 215 associated with a Service Management and Orchestration (SMO) Framework 205, or both) . A CU 210 may communicate with one or more distributed units (DUs) 230 via respective midhaul links, such as an F1 interface. The DUs 230 may communicate with one or more radio units (RUs) 240 via respective fronthaul links. The RUs 240 may communicate with respective UEs 104 via one or more radio frequency (RF) access links. In some implementations, the UE 104 may be simultaneously served by multiple RUs 240.

Each of the units, e.g., the CUs 210, the DUs 230, the RUs 240, as well as the Near-RT RICs 225, the Non-RT RICs 215 and the SMO Framework 205, may include one or more interfaces or be coupled to one or more interfaces configured to receive or transmit signals, data, or information (collectively, signals) via a wired or wireless transmission medium. Each of the units, or an associated processor or controller providing instructions to the communications interfaces of the units, can be configured to communicate with one or more of the other units via the transmission medium. For example, the units can include a wired interface configured to receive or transmit signals over a wired transmission medium to one or more of the other units. Additionally or alternatively, the units can include a wireless interface, which may include a receiver, a transmitter or transceiver (such as a radio frequency (RF) transceiver) , configured to receive or transmit signals, or both, over a wireless transmission medium to one or more of the other units.

In some aspects, the CU 210 may host one or more higher layer control functions. Such control functions can include radio resource control (RRC) , packet data convergence protocol (PDCP) , service data adaptation protocol (SDAP) , or the like. Each control function can be implemented with an interface configured to communicate signals with other control functions hosted by the CU 210. The CU 210 may be configured to handle user plane functionality (e.g., Central Unit –User Plane (CU-UP) ) , control plane functionality (e.g., Central Unit –Control Plane (CU-CP) ) , or a combination thereof. In some implementations, the CU 210 can be logically split into one or more CU-UP units and one or more CU-CP units. The CU-UP unit can communicate bidirectionally with the CU-CP unit via an interface, such as the E1 interface when implemented in an O-RAN configuration. The CU 210 can be implemented to communicate with the DU 230, as necessary, for network control and signaling.

The DU 230 may correspond to a logical unit that includes one or more base station functions to control the operation of one or more RUs 240. In some aspects, the DU 230 may host one or more of a radio link control (RLC) layer, a medium access control (MAC) layer, and one or more high physical (PHY) layers (such as modules for forward error correction (FEC) encoding and decoding, scrambling, modulation and demodulation, or the like) depending, at least in part, on a functional split, such as those defined by the 3 ^rd Generation Partnership Project (3GPP) . In some aspects, the DU 230 may further host one or more low PHY layers. Each layer (or module) can be implemented with an interface configured to communicate signals with other layers (and modules) hosted by the DU 230, or with the control functions hosted by the CU 210.

Lower-layer functionality can be implemented by one or more RUs 240. In some deployments, an RU 240, controlled by a DU 230, may correspond to a logical node that hosts RF processing functions, or low-PHY layer functions (such as performing fast Fourier transform (FFT) , inverse FFT (iFFT) , digital beamforming, physical random access channel (PRACH) extraction and filtering, or the like) , or both, based at least in part on the functional split, such as a lower layer functional split. In such an architecture, the RU (s) 240 can be implemented to handle over the air (OTA) communications with one or more UEs 104. In some implementations, real-time and non-real-time aspects of control and user plane communications with the RU (s) 240 can be controlled by the corresponding DU 230. In some scenarios, this configuration can enable the DU (s) 230 and the CU 210 to be implemented in a cloud-based RAN architecture, such as a vRAN architecture.

The SMO Framework 205 may be configured to support RAN deployment and provisioning of non-virtualized and virtualized network elements. For non-virtualized network elements, the SMO Framework 205 may be configured to support the deployment of dedicated physical resources for RAN coverage requirements which may be managed via an operations and maintenance interface (such as an O1 interface) . For virtualized network elements, the SMO Framework 205 may be configured to interact with a cloud computing platform (such as an open cloud (O-Cloud) 290) to perform network element life cycle management (such as to instantiate virtualized network elements) via a cloud computing platform interface (such as an O2 interface) . Such virtualized network elements can include, but are not limited to, CUs 210, DUs 230, RUs 240 and Near-RT RICs 225. In some implementations, the SMO Framework 205 can communicate with a hardware aspect of a 4G RAN, such as an open eNB (O-eNB) 211, via an O1 interface. Additionally, in some implementations, the SMO Framework 205 can communicate directly with one or more RUs 240 via an O1 interface. The SMO Framework 205 also may include a Non-RT RIC 215 configured to support functionality of the SMO Framework 205.

The Non-RT RIC 215 may be configured to include a logical function that enables non-real-time control and optimization of RAN elements and resources, Artificial Intelligence/Machine Learning (AI/ML) workflows including model training and updates, or policy-based guidance of applications/features in the Near-RT RIC 225. The Non-RT RIC 215 may be coupled to or communicate with (such as via an A1 interface) the Near-RT RIC 225. The Near-RT RIC 225 may be configured to include a logical function that enables near-real-time control and optimization of RAN elements and resources via data collection and actions over an interface (such as via an E2 interface) connecting one or more CUs 210, one or more DUs 230, or both, as well as an O-eNB, with the Near-RT RIC 225.

In some implementations, to generate AI/ML models to be deployed in the Near-RT RIC 225, the Non-RT RIC 215 may receive parameters or external enrichment information from external servers. Such information may be utilized by the Near-RT RIC 225 and may be received at the SMO Framework 205 or the Non-RT RIC 215 from non-network data sources or from network functions. In some examples, the Non-RT RIC 215 or the Near-RT RIC 225 may be configured to tune RAN behavior or performance. For example, the Non-RT RIC 215 may monitor long-term trends and patterns for performance and employ AI/ML models to perform corrective actions through the SMO Framework 205 (such as reconfiguration via O1) or via creation of RAN management policies (such as A1 policies) .

FIG. 3 depicts aspects of an example BS 102 and a UE 104.

Generally, BS 102 includes various processors (e.g., 320, 330, 338, and 340) , antennas 334a-t (collectively 334) , transceivers 332a-t (collectively 332) , which include modulators and demodulators, and other aspects, which enable wireless transmission of data (e.g., data source 312) and wireless reception of data (e.g., data sink 339) . For example, BS 102 may send and receive data between BS 102 and UE 104. BS 102 includes controller/processor 340, which may be configured to implement various functions described herein related to wireless communications.

Generally, UE 104 includes various processors (e.g., 358, 364, 366, and 380) , antennas 352a-r (collectively 352) , transceivers 354a-r (collectively 354) , which include modulators and demodulators, and other aspects, which enable wireless transmission of data (e.g., retrieved from data source 362) and wireless reception of data (e.g., provided to data sink 360) . UE 104 includes controller/processor 380, which may be configured to implement various functions described herein related to wireless communications.

In regards to an example downlink transmission, BS 102 includes a transmit processor 320 that may receive data from a data source 312 and control information from a controller/processor 340. The control information may be for the physical broadcast channel (PBCH) , physical control format indicator channel (PCFICH) , physical HARQ indicator channel (PHICH) , physical downlink control channel (PDCCH) , group common PDCCH (GC PDCCH) , and/or others. The data may be for the physical downlink shared channel (PDSCH) , in some examples.

Transmit processor 320 may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. Transmit processor 320 may also generate reference symbols, such as for the primary synchronization signal (PSS) , secondary synchronization signal (SSS) , PBCH demodulation reference signal (DMRS) , and channel state information reference signal (CSI-RS) .

Transmit (TX) multiple-input multiple-output (MIMO) processor 330 may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, and/or the reference symbols, if applicable, and may provide output symbol streams to the modulators (MODs) in transceivers 332a-332t. Each modulator in transceivers 332a-332t may process a respective output symbol stream to obtain an output sample stream. Each modulator may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. Downlink signals from the modulators in transceivers 332a-332t may be transmitted via the antennas 334a-334t, respectively.

In order to receive the downlink transmission, UE 104 includes antennas 352a-352r that may receive the downlink signals from the BS 102 and may provide received signals to the demodulators (DEMODs) in transceivers 354a-354r, respectively. Each demodulator in transceivers 354a-354r may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each demodulator may further process the input samples to obtain received symbols.

MIMO detector 356 may obtain received symbols from all the demodulators in transceivers 354a-354r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. Receive processor 358 may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for the UE 104 to a data sink 360, and provide decoded control information to a controller/processor 380.

In regards to an example uplink transmission, UE 104 further includes a transmit processor 364 that may receive and process data (e.g., for the PUSCH) from a data source 362 and control information (e.g., for the physical uplink control channel (PUCCH) ) from the controller/processor 380. Transmit processor 364 may also generate reference symbols for a reference signal (e.g., for the sounding reference signal (SRS)) . The symbols from the transmit processor 364 may be precoded by a TX MIMO processor 366 if applicable, further processed by the modulators in transceivers 354a-354r (e.g., for SC-FDM) , and transmitted to BS 102.

At BS 102, the uplink signals from UE 104 may be received by antennas 334a-t, processed by the demodulators in transceivers 332a-332t, detected by a MIMO detector 336 if applicable, and further processed by a receive processor 338 to obtain decoded data and control information sent by UE 104. Receive processor 338 may provide the decoded data to a data sink 339 and the decoded control information to the controller/processor 340.

Memories

342 and 382 may store data and program codes for BS 102 and UE 104, respectively.

Scheduler 344 may schedule UEs for data transmission on the downlink and/or uplink.

In various aspects, BS 102 may be described as transmitting and receiving various types of data associated with the methods described herein. In these contexts, “transmitting” may refer to various mechanisms of outputting data, such as outputting data from data source 312, scheduler 344, memory 342, transmit processor 320, controller/processor 340, TX MIMO processor 330, transceivers 332a-t, antenna 334a-t, and/or other aspects described herein. Similarly, “receiving” may refer to various mechanisms of obtaining data, such as obtaining data from antennas 334a-t, transceivers 332a-t, RX MIMO detector 336, controller/processor 340, receive processor 338, scheduler 344, memory 342, and/or other aspects described herein.

In various aspects, UE 104 may likewise be described as transmitting and receiving various types of data associated with the methods described herein. In these contexts, “transmitting” may refer to various mechanisms of outputting data, such as outputting data from data source 362, memory 382, transmit processor 364, controller/processor 380, TX MIMO processor 366, transceivers 354a-t, antenna 352a-t, and/or other aspects described herein. Similarly, “receiving” may refer to various mechanisms of obtaining data, such as obtaining data from antennas 352a-t, transceivers 354a-t, RX MIMO detector 356, controller/processor 380, receive processor 358, memory 382, and/or other aspects described herein.

In some aspects, a processor may be configured to perform various operations, such as those associated with the methods described herein, and transmit (output) to or receive (obtain) data from another interface that is configured to transmit or receive, respectively, the data.

FIGS. 4A, 4B, 4C, and 4D depict aspects of data structures for a wireless communications network, such as wireless communications network 100 of FIG. 1.

In particular, FIG. 4A is a diagram 400 illustrating an example of a first subframe within a 5G (e.g., 5G NR) frame structure, FIG. 4B is a diagram 430 illustrating an example of DL channels within a 5G subframe, FIG. 4C is a diagram 450 illustrating an example of a second subframe within a 5G frame structure, and FIG. 4D is a diagram 480 illustrating an example of UL channels within a 5G subframe.

Wireless communications systems may utilize orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) on the uplink and downlink. Such systems may also support half-duplex operation using time division duplexing (TDD) . OFDM and single-carrier frequency division multiplexing (SC-FDM) partition the system bandwidth (e.g., as depicted in FIGS. 4B and 4D) into multiple orthogonal subcarriers. Each subcarrier may be modulated with data. Modulation symbols may be sent in the frequency domain with OFDM and/or in the time domain with SC-FDM.

A wireless communications frame structure may be frequency division duplex (FDD) , in which, for a particular set of subcarriers, subframes within the set of subcarriers are dedicated for either DL or UL. Wireless communications frame structures may also be time division duplex (TDD) , in which, for a particular set of subcarriers, subframes within the set of subcarriers are dedicated for both DL and UL.

In FIG. 4A and 4C, the wireless communications frame structure is TDD where D is DL, U is UL, and X is flexible for use between DL/UL. UEs may be configured with a slot format through a received slot format indicator (SFI) (dynamically through DL control information (DCI) , or semi-statically/statically through radio resource control (RRC) signaling) . In the depicted examples, a 10 ms frame is divided into 10 equally sized 1 ms subframes. Each subframe may include one or more time slots. In some examples, each slot may include 7 or 14 symbols, depending on the slot format. Subframes may also include mini-slots, which generally have fewer symbols than an entire slot. Other wireless communications technologies may have a different frame structure and/or different channels.

In certain aspects, the number of slots within a subframe is based on a slot configuration and a numerology. For example, for slot configuration 0, different numerologies (μ) 0 to 5 allow for 1, 2, 4, 8, 16, and 32 slots, respectively, per subframe. For slot configuration 1, different numerologies 0 to 2 allow for 2, 4, and 8 slots, respectively, per subframe. Accordingly, for slot configuration 0 and numerology μ, there are 14 symbols/slot and 2μ slots/subframe. The subcarrier spacing and symbol length/duration are a function of the numerology. The subcarrier spacing may be equal to 2 ^μ×15 kHz, where μ is the numerology 0 to 5. As such, the numerology μ=0 has a subcarrier spacing of 15 kHz and the numerology μ=5 has a subcarrier spacing of 480 kHz. The symbol length/duration is inversely related to the subcarrier spacing. FIGS. 4A, 4B, 4C, and 4D provide 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.

As depicted in FIGS. 4A, 4B, 4C, and 4D, a resource grid may be used to represent the frame structure. Each time slot includes a resource block (RB) (also referred to as physical RBs (PRBs) ) that extends, for example, 12 consecutive subcarriers. The resource grid is divided into multiple resource elements (REs) . The number of bits carried by each RE depends on the modulation scheme.

As illustrated in FIG. 4A, some of the REs carry reference (pilot) signals (RS) for a UE (e.g., UE 104 of FIGS. 1 and 3) . The RS may include demodulation RS (DMRS) and/or channel state information reference signals (CSI-RS) for channel estimation at the UE.The RS may also include beam measurement RS (BRS) , beam refinement RS (BRRS) , and/or phase tracking RS (PT-RS) .

FIG. 4B 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 CCE including, for example, nine RE groups (REGs) , each REG including, for example, four consecutive REs in an OFDM symbol.

A primary synchronization signal (PSS) may be within symbol 2 of particular subframes of a frame. The PSS is used by a UE (e.g., 104 of FIGS. 1 and 3) to determine subframe/symbol timing and a physical layer identity.

A secondary synchronization signal (SSS) may be within symbol 4 of particular subframes of a frame. The SSS is used by a UE to determine a 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 locations of the aforementioned DMRS. The physical broadcast channel (PBCH) , which carries a master information block (MIB) , may be logically grouped with the PSS and SSS to form a synchronization signal (SS) /PBCH block. The MIB provides a number of RBs in the system bandwidth and a system frame number (SFN) . The physical downlink shared channel (PDSCH) carries user data, broadcast system information not transmitted through the PBCH such as system information blocks (SIBs) , and/or paging messages.

As illustrated in FIG. 4C, some of the REs carry DMRS (indicated as R for one particular configuration, but other DMRS configurations are possible) for channel estimation at the base station. The UE may transmit DMRS for the PUCCH and DMRS for the PUSCH. The PUSCH DMRS may be transmitted, for example, in the first one or two symbols of the PUSCH. The PUCCH DMRS may be transmitted in different configurations depending on whether short or long PUCCHs are transmitted and depending on the particular PUCCH format used. UE 104 may transmit sounding reference signals (SRS) . The SRS may be transmitted, for example, in the last symbol of a subframe. The SRS may have a comb structure, and a UE may transmit SRS on one of the combs. The SRS may be used by a base station for channel quality estimation to enable frequency-dependent scheduling on the UL.

FIG. 4D illustrates an example of various UL channels within a subframe of a frame. The PUCCH may be located as indicated in one configuration. The PUCCH carries uplink control information (UCI) , such as scheduling requests, a channel quality indicator (CQI) , a precoding matrix indicator (PMI) , a rank indicator (RI) , and HARQ ACK/NACK feedback. The PUSCH carries data, and may additionally be used to carry a buffer status report (BSR) , a power headroom report (PHR) , and/or UCI.

QCL port and TCI States

In many cases, it is important for a UE to know which assumptions it can make on a channel corresponding to different transmissions. For example, the UE may need to know which reference signals it can use to estimate the channel in order to decode a transmitted signal (e.g., PDCCH or PDSCH) . It may also be important for the UE to be able to report relevant channel state information (CSI) to the BS (gNB) for scheduling, link adaptation, and/or beam management purposes. In NR, the concept of quasi co-location (QCL) and transmission configuration indicator (TCI) states is used to convey information about these assumptions.

QCL assumptions are generally defined in terms of channel properties. Per 3GPP TS 38.214, “two antenna ports are said to be quasi-co-located if properties of the channel over which a symbol on one antenna port is conveyed can be inferred from the channel over which a symbol on the other antenna port is conveyed. ” Different reference signals may be considered quasi co-located ( “QCL’d” ) if a receiver (e.g., a UE) can apply channel properties determined by detecting a first reference signal to help detect a second reference signal. TCI states generally include configurations such as QCL-relationships, for example, between the DL RSs in one CSI-RS set and the PDSCH DMRS ports.

In some cases, a UE may be configured with up to M TCI-States. Configuration of the M TCI-States can come about via higher layer signalling, while a UE may be signalled to decode PDSCH according to a detected PDCCH with DCI indicating one of the TCI states. Each configured TCI state may include one RS set TCI-RS-SetConfig that indicates different QCL assumptions between certain source and target signals.

For example, TCI-RS-SetConfig may indicate a source reference signal (RS) is indicated in the top block and is associated with a target signal indicated in the bottom block. In this context, a target signal generally refers to a signal for which channel properties may be inferred by measuring those channel properties for an associated source signal. As noted above, a UE may use the source RS to determine various channel parameters, depending on the associated QCL type, and use those various channel properties (determined based on the source RS) to process the target signal. A target RS does not necessarily need to be PDSCH’s DMRS, rather it can be any other RS: PUSCH DMRS, CSIRS, TRS, and SRS.

Each TCI-RS-SetConfig may contain various parameters. These parameters can, for example, configure quasi co-location relationship (s) between reference signals in the RS set and the DM-RS port group of the PDSCH. The RS set contains a reference to either one or two DL RSs and an associated quasi co-location type (QCL-Type) for each one configured by the higher layer parameter QCL-Type.

For the case of two DL RSs, the QCL types can take on a variety of arrangements. For example, QCL types may not be the same, regardless of whether the references are to the same DL RS or different DL RSs. In the illustrated example, SSB is associated with Type C QCL for P-TRS, while CSI-RS for beam management (CSIRS–BM) is associated with Type D QCL.

QCL information and/or types may in some scenarios depend on or be a function of other information. For example, the quasi co-location (QCL) types indicated to the UE can be based on higher layer parameter QCL-Type and may take one or a combination of the following types:

QCL-TypeA: {Doppler shift, Doppler spread, average delay, delay spread} ,

QCL-TypeB: {Doppler shift, Doppler spread} ,

QCL-TypeC: {average delay, Doppler shift} , and

QCL-TypeD: {Spatial Rx parameter} ,

Spatial QCL assumptions (QCL-TypeD) may be used to help a UE to select an analog Rx beam (e.g., during beam management procedures) . For example, an SSB resource indicator may indicate a same beam for a previous reference signal should be used for a subsequent transmission.

An initial CORESET (e.g., CORESET ID 0 or simply CORESET#0) in NR may be identified during initial access by a UE (e.g., via a field in the MIB) . A ControlResourceSet information element (CORESET IE) sent via radio resource control (RRC) signaling may convey information regarding a CORESET configured for a UE. The CORESET IE generally includes a CORESET ID, an indication of frequency domain resources (e.g., number of RBs) assigned to the CORESET, contiguous time duration of the CORESET in a number of symbols, and Transmission Configuration Indicator (TCI) states.

As noted above, a subset of the TCI states provide quasi co-location (QCL) relationships between DL RS (s) in one RS set (e.g., TCI-Set) and PDCCH demodulation RS (DMRS) ports. A particular TCI state for a given UE (e.g., for unicast PDCCH) may be conveyed to the UE by the Medium Access Control (MAC) Control Element (MAC- CE) . The particular TCI state is generally selected from the set of TCI states conveyed by the CORESET IE, with the initial CORESET (CORESET#0) generally configured via MIB.

Search space information may also be provided via RRC signaling. For example, the SearchSpace IE is another RRC IE that defines how and where to search for PDCCH candidates for a given CORESET. Each search space is associated with one CORESET. The SearchSpace IE identifies a search space configured for a CORESET by a search space ID. In an aspect, the search space ID associated with CORESET #0 is SearchSpace ID #0. The search space is generally configured via PBCH (MIB) .

Example SRS Based Transmissions

Some deployments (e.g., NR Release 15 and 16 systems) support codebook-based transmission and non-codebook-based transmission schemes for uplink transmissions with wideband precoders. Codebook-based UL transmission is based on BS configuration and can be used in cases where reciprocity may not hold.

FIG. 5 is a call flow diagram 500 illustrating an example of conventional codebook based UL transmission using a wideband precoder. As illustrated, a UE transmits (non-precoded) SRS with up to 2 SRS resources (with each resource having 1, 2 or 4 ports) . The gNB measures the SRS and, based on the measurement, selects one SRS resource and a wideband precoder to be applied to the SRS ports within the selected resource.

As illustrated, the gNB configures the UE with the selected SRS resource via an SRS resource indictor (SRI) and with the wideband precoder via a transmit precoder matrix indicator (TPMI) . For a dynamic grant, the SRI and TPMI may be configured via DCI format 0_1. For a configured grant (e.g., for semi-persistent uplink) , SRI and TPMI may be configured via RRC or DCI.

The UE determines the selected SRS resource from the SRI and precoding from TPMI and transmits PUSCH accordingly.

FIG. 6 is a call flow diagram 600 illustrating an example of non-codebook based UL transmission. As illustrated, a UE transmits (precoded) SRS. While the example shows 2 SRS resources, the UE may transmit with up to 4 SRS resources (with each resource having 1 port) . The gNB measures the SRS and, based on the measurement, selects one or more SRS resource. In this case, since the UE sent the SRS precoded, by selecting the SRS resource, the gNB is effectively also selecting precoding. For non-codebook based UL transmission, each SRS resource corresponds to a layer. The precoder of the layer is actually the precoder of the SRS which is emulated by the UE. Selecting N SRS resources means the rank is N. The UE is to transmit PUSCH using the same precoder as the SRS.

As illustrated, the gNB configures the UE with the selected SRS resource via an SRS resource indictor (SRI) . For a dynamic grant, the SRI may be configured via DCI format 0_1. For a configured grant, the SRI may be configured via RRC or DCI.

Overview of Unified TCI Types

In some cases (e.g., according to NR Release 17) , a unified TCI state may indicate a common beam applicable to multiple DL/UL channels. In other words, once a unified TCI state is configured, it can be used for not just a single channel, but for multiple channels/signals simultaneously, which may reduce signalling overhead and latency. For example, a unified TCI state may be applied for a CSI-RS, a CORESET, and a PDSCH. A common beam may also be applied for uplink channels/signals, e.g., a PUSCH, a dedicated PUCCH, and an SRS, depending on how the UE is configured

Various types of unified TCI may be defined. For example, unified TCI types may include:

Type 1: Joint downlink (DL) /UL common TCI state to indicate a common beam; for at least one DL channel/reference signal (RS_plus at least one UL channel/RS

Type 2: Separate DL common TCI state to indicate a common beam for more than one DL channel/RS;

Type 3: Separate UL common TCI state to indicate a common beam for more than one UL channel/RS;

Type 4: Separate DL single channel/RS TCI state to indicate a beam for a single DL channel/RS; and

Type 5: Separate UL single channel/RS TCI state to indicate a beam for a single UL channel/RS.

FIG. 7 illustrates an example configuration of unified TCI states that may be configured, for example, via radio resource control (RRC) signaling.

Overview of MAC CE TCI Activation

As noted above, in order to indicate a beam for SP or AP SRS, one or more of the TCI states may be activated via a medium access control (MAC) control element (CE) .

FIG. 8 illustrates an example of a MAC CE format for activating and deactivating TCI states for SP SRS.

As illustrated, the MAC CE may include a first field (A/D) that indicates whether to activate or deactivate indicated SP SRS resource set. The field may be set to 1 to indicate activation or 0 to indicate deactivation. The MAC CE may also include an SRS Resource Set's Cell ID field that indicates the identity of the Serving Cell, which contains activated/deactivated SP SRS Resource Set. If a C field of the MAC CE is set to 0, this field may also indicate the identity of the Serving Cell which contains all resources indicated by the Resource ID _i fields.

The MAC CE may also include an SRS Resource Set's BWP ID field that indicates an uplink (UL) bandwidth part (BWP) as a codepoint of the DCI bandwidth part indicator field, which contains activated/deactivated SP SRS Resource Set. If the C field is set to 0, this field may also indicate the identity of the BWP which contains all resources indicated by the Resource ID _i fields.

The C field may indicate whether the octets containing Resource Serving Cell ID field (s) and Resource BWP ID field (s) are present. If the C field is set to 1, the octets containing Resource Serving Cell ID field (s) and Resource BWP ID field (s) are present, otherwise they are not present. A supplemental uplink (SUL) field may indicate whether the MAC CE applies to the normal uplink (NUL) carrier or SUL carrier configuration. This field is set to 1 to indicate that it applies to the SUL carrier configuration, and it is set to 0 to indicate that it applies to the NUL carrier configuration.

The MAC CE also includes an SP SRS Resource Set ID that indicates the SP SRS Resource Set ID identified by SRS-ResourceSetId is to be activated or deactivated. The MAC CE may also include a field, F _i, that indicates the type of a resource used as a spatial relationship for SRS resource within SP SRS Resource Set indicated with SP SRS Resource Set ID field. F ₀ refers to the first SRS resource within the resource set, F ₁ to the second one and so on. The field is set to 1 to indicate NZP CSI-RS resource index is used, and it is set to 0 to indicate either SSB index or SRS resource index is used. The length of the field is 1 bit. This field may only be present if MAC CE is used for activation (i.e. when the A/D field is set to 1) .

The MAC CE also includes a Resource ID _i field that contains an identifier of the resource used for spatial relationship derivation for SRS resource i. Resource ID ₀ refers to the first SRS resource within the resource set, Resource ID ₁ to the second one and so on. If F _i is set to 0, and the first bit of this field is set to 1, the remainder of this field contains SSB-Index as specified in TS 38.331 [5] . If F _i is set to 0, and the first bit of this field is set to 0, the remainder of this field contains SRS-ResourceId. The length of the field is 7 bits. This field is only present if MAC CE is used for activation (i.e., when the A/D field is set to 1) .

The MAC CE also includes a Resource Serving Cell ID _i field that indicates the identity of the Serving Cell on which the resource used for spatial relationship derivation for SRS resource i is located. The MAC CE also includes a Resource BWP ID _i: field that indicates a UL BWP as the codepoint of the DCI bandwidth part indicator field, on which the resource used for spatial relationship derivation for SRS resource i is located. The MAC CE also includes a Reserved bit (R) set to 0.

FIG. 9 illustrates an example of another MAC CE format that may be considered enhanced for activating and deactivating TCI states for SP SRS. As illustrated, many of the fields are similar to the MAC CE format shown in FIG. 8, however some fields may be different and functions of common fields may be different.

For example, the A/D field may again indicate whether to activate or deactivate indicated SP SRS resource set. However, if the indicated SRS resource set ID is for the AP SRS resource set, the MAC entity (at the UE) may ignore this field. The C field may again indicate whether the octets containing Resource Serving Cell ID field (s) and Resource BWP ID field (s) are present. If this field is set to 1, Resource Serving Cell ID field (s) and Resource BWP ID field (s) are present, otherwise they are not present so the MAC entity (UE) may ignore Resource Serving Cell ID field (s) and Resource BWP ID field (s) .

The MAC CE of FIG. 9 includes a Resource ID _i field that contains an identifier of the resource used for spatial relationship derivation for SRS resource i. Resource ID ₀ refers to the first SRS resource within the resource set, Resource ID ₁ to the second one and so on. If F _i is set to 0, the first bit of this field is always set to 0. If F _i is set to 0, and the second bit of this field is set to 1, the remainder of this field contains SSB-Index as specified in TS 38.331 [5] . If F _i is set to 0, and the second bit of this field is set to 0, the remainder of this field contains SRS-ResourceId as specified in TS 38.331 [5] . The length of the field is 8 bits. This field is only present if MAC CE is used for activation of SP SRS resource set, i.e. the A/D field is set to 1, or for AP SRS resource set.

FIG. 10 illustrates an example of another MAC CE format for serving-cell based SRS spatial relation indication. As illustrated, many of the fields are similar to the MAC CE formats shown in FIGs. 8 and 9, however some fields may be different and functions of common fields may be different.

The MAC CE of FIG. 10 includes an SRS Resource's Cell ID field that indicates the identity of the Serving Cell, which contains the indicated SP/AP SRS Resource. If the C field is set to 0, this field also indicates the identity of the Serving Cell which contains all resources indicated by the Resource IDi fields. The indicated Serving Cell may configured as part of a simultaneousSpatial-UpdatedList1 or simultaneousSpatial-UpdatedList2, and this MAC CE applies to all the Serving Cells configured in the set simultaneousSpatial-UpdatedList1 or simultaneousSpatial-UpdatedList2, respectively.

The MAC CE of FIG. 10 includes a Resource ID _i field that contains an identifier of the resource used for spatial relationship derivation for SRS resource i. Resource ID ₀ refers to the first SRS resource which is indicated SRS Resource ID ₀, Resource ID ₁ to the second one and so on. If F _i is set to 0, the first bit of this field is always set to 0. If F _i is set to 0, and the second bit of this field is set to 1, the remainder of this field contains SSB-Index. If F _i is set to 0, and the second bit of this field is set to 0, the remainder of this field contains SRS-ResourceId. The length of the field is 8 bits.

Aspects Related to Unified TCI Activation MAC-CE for SRS

As illustrated in the call flow diagram of FIG. 11, in some cases, aspects of the present disclosure propose new MAC CE formats to support unified TCI activation for SRS.

As illustrated, the UE may receive signaling from a network entity (e.g., a gNB or node of a disaggregated base station) configuring the UE with at least one of an SRS resource set or one or more unified TCI states for SRS.

The network entity may activate at least one of the unified TCI states for at least one SRS resource in the SRS resource set. The UE may then transmit SRS via the SRS resource in accordance with the activated or deactivated unified TCI state.

Aspects of the present disclosure provide various options, for SRS transmissions, whether an SRS resource set is or is not configured by a higher layer, such as RRC signaling, with a parameter such as followUnifiedTCIstateSRS.

For example, according to a first proposal, when the UE is configured with unified TCI states, and is not configured with the RRC parameter followunifiedTCIstateSRS for an SRS resource in a semi-persistent (SP) or aperiodic (AP) SRS set, the MAC CE can activate a unified TCI state for the SRS in SP/AP SRS set.

In some cases, the MAC CE may include a TCI indication field. The TCI indication field may include, for each SRS in an SRS set, a dedicated bit that identifies whether the indicated unified TCI is for a joint TCI, or for an uplink TCI. The TCI indication field may also indicate, for each SRS in the SRS set, the unified TCI ID, which can be for joint TCI, or for uplink TCI.

Other information in the MAC C-CE may include, for example, an A/D field that indicates whether to activate or deactivate indicated SP SRS resource set. The MAC CE may also include at least one of a Cell ID or a BWP ID for an SRS Resource Set, or for a SRS Resource in the SRS set.

According to a second proposal, when a UE is configured with unified TCI states, and is configured with the RRC parameter “followunifiedTCIstateSRS” for an SRS resource in a semi-persistent (SP) or aperiodic (AP) SRS set, a MAC CE may activate an SP SRS set without any TCI indication. In other words, in this case, the UE may use the unified TCI state indicated for other uplink channel (such as PUCCH and/or PUSCH) for the SRS resource (so the TCI state does not need to be explicitly indicated in the MAC CE) .

FIGs. 12A/12B illustrate an example of a MAC CE format (e.g., an enhanced SP/AP SRS TCI indication MAC CE) that may be used to activate and deactivate TCI states for SRS, in accordance with aspects of the present disclosure. FIGs. 13A/13B illustrates an example of a MAC CE format (e.g., a serving cell set based SRS unified TCI indication MAC CE format) that may be used to indicate TCI for SRS. As illustrated, many of the fields may similar to the MAC CE formats described above, however some fields may be different and functions of common fields may be different.

For example, the MAC CE formats of may include F _i field may indicate the type of a unified TCI for SRS resource within SRS Resource Set indicated with SRS Resource Set ID field. F ₀ may refer to the first SRS resource within the resource set, F ₁ to the second one and so on. The field is set to 1 to indicate joint TCI is used, and it is set to 0 to indicate an uplink TCI is used. This field may be present if the SRS resource set is not configured with a RRC parameter “followunifiedTCIstateSRS. ” Otherwise, as illustrated in FIG. 12B and FIG. 13B, the field may not be present.

The MAC CE may also include a TCI state ID that indicates the TCI state identified by TCI-StateId. If Fi is set to 1, for example, a 7-bit length TCI state ID (i.e., TCI-StateId) may be used. If Fi is set to 0, the most significant bit of a TCI state ID may be considered as a reserved bit and the remaining 6 bits may indicate the UL-TCIState-Id. This field may be present if the SRS resource set is not configured with a RRC parameter “followunifiedTCIstateSRS. ” Otherwise, as illustrated in FIG. 12B and FIG. 13B, this field may not be present.

According to a third proposal, when a UE is configured with unified TCI states, and is not configured with the RRC parameter “followunifiedTCIstateSRS” for an SRS in a semi-persistent (SP) or aperiodic (AP) SRS set, a MAC CE can activate a unified TCI state for the SRS in SP/AP SRS set. The MAC CE may include a TCI indication field which may indicate, for each SRS in SRS set, the unified TCI ID, which can be for joint TCI, or for uplink TCI. In some cases, The RRC configuration may configure either only joint TCIs, or only uplink TCIs to the UE (e.g., downlink only TCIs may not apply to SRS transmissions) .

Other information in the MAC-CE may include, for example, an A/D field that indicates whether to activate or deactivate indicated SP SRS resource set. The MAC CE may also include at least one of a Cell ID or BWP ID for an SRS Resource Set or for an SRS Resource in a SRS set.

According to a fourth proposal, when a UE is configured with unified TCI states, and is configured with the RRC parameter “followunifiedTCIstateSRS” for a SRS in a semi-persistent (SP) or aperiodic (AP) SRS set, a MAC CE can activate an SP SRS set without any TCI indication.

FIGs. 14A/14B illustrates an example of a MAC CE format (e.g., an enhanced SP/AP SRS TCI indication MAC CE) that may be used to activate and deactivate TCI states for SRS, in accordance with aspects of the present disclosure. FIGs. 15A/15B illustrates an example of a MAC CE format (e.g., a serving cell set based SRS unified TCI indication MAC CE format) that may be used to indicate TCI for SRS. As illustrated, many of the fields may be similar to the MAC CE formats described above, however some fields may be different and functions of common fields may be different.

For example, the MAC CE formats may include a TCI state ID field. This field may indicate the TCI state identified by TCI-StateId. For a joint TCI state, a 7-bit length TCI state ID may be used. For an uplink TCI, the most significant bit of TCI state ID may be considered as the reserved bit and remaining 6 bits may indicate the UL-TCIState-Id. This field may be present if the SRS resource set is not configured with a RRC parameter “followunifiedTCIstateSRS. ” Otherwise, as illustrated in FIG. 14B and FIG. 15B this field may not be present.

Example Operations of a User Equipment

FIG. 16 shows an example of a method 1600 for wireless communications by a UE, such as UE 104 of FIGS. 1 and 3.

Method 1600 begins at step 1605 with obtaining first signaling configuring the UE with at least one of a SRS resource set or one or more unified TCI states for a SRS. In some cases, the operations of this step refer to, or may be performed by, circuitry for obtaining and/or code for obtaining as described with reference to FIG. 18.

Method 1600 then proceeds to step 1610 with obtaining second signaling activating or deactivating at least one of the unified TCI states for at least one SRS resource in the SRS resource set. In some cases, the operations of this step refer to, or may be performed by, circuitry for obtaining and/or code for obtaining as described with reference to FIG. 18.

Method 1600 then proceeds to step 1615 with outputting, for transmission, the SRS via the SRS resource in accordance with the activated or deactivated unified TCI state. In some cases, the operations of this step refer to, or may be performed by, circuitry for outputting and/or code for outputting as described with reference to FIG. 18.

In some aspects, the first signaling indicates a plurality of SRS resource sets including the SRS resource set, each SRS resource set including one or more SRS resources.

In some aspects, each of the unified TCI states indicates a common beam associated with multiple signals.

In some aspects, the first signaling comprises RRC signaling; and the second signaling comprises a MAC-CE.

In some aspects, the MAC CE includes at least one of: a first field indicating whether to activate or deactivate the SRS resource set; a second field indicating a cell ID for the SRS resource set or for an SRS resource in the SRS resource set; or a third field indicating a bandwidth part ID for the SRS resource set or for an SRS resource in the SRS resource set.

In some aspects, the SRS resource set is configured as a semi-persistent or aperiodic SRS resource set; and the first signaling configures the SRS resource set with a configuration that includes a parameter indicating the SRS resource set is to follow a unified TCI state.

In some aspects, the MAC CE lacks an indication of the activated or deactivated unified TCI state.

In some aspects, the SRS resource set is configured as a semi-persistent or aperiodic SRS resource set; and the first signaling configures the SRS resource set with a configuration that lacks a parameter indicating the SRS resource set is to follow a unified TCI state.

In some aspects, the MAC CE includes, for one or more SRS resources in the SRS resource set: an ID for the unified TCI state; and an indication of whether the unified TCI state is for: a joint TCI state that indicates a common beam for at least one downlink signal and at least one uplink signal, or an uplink TCI state that indicates a common beam for multiple uplink signals.

In some aspects, the MAC CE includes, for one or more SRS resources in the SRS resource set: an ID for the unified TCI state.

In some aspects, the first signaling configures each of the one or more unified TCI states for SRS as: a joint TCI state that indicates a common beam for at least one downlink signal and at least one uplink signal; or an uplink TCI state that indicates a common beam for multiple uplink signals.

In one aspect, method 1600, or any aspect related to it, may be performed by an apparatus, such as communications device 1800 of FIG. 18, which includes various components operable, configured, or adapted to perform the method 1600. Communications device 1800 is described below in further detail.

Note that FIG. 16 is just one example of a method, and other methods including fewer, additional, or alternative steps are possible consistent with this disclosure.

Example Operations of a Network Entity

FIG. 17 shows an example of a method 1700 for wireless communications by a network entity, such as BS 102 of FIGS. 1 and 3, or a disaggregated base station as discussed with respect to FIG. 2.

Method 1700 begins at step 1705 with outputting, for transmission, first signaling configuring a UE with at least one of a SRS resource set or one or more unified TCI states for a SRS. In some cases, the operations of this step refer to, or may be performed by, circuitry for outputting and/or code for outputting as described with reference to FIG. 19.

Method 1700 then proceeds to step 1710 with outputting, for transmission, second signaling activating or deactivating at least one of the unified TCI states for at least one SRS resource in the SRS resource set. In some cases, the operations of this step refer to, or may be performed by, circuitry for outputting and/or code for outputting as described with reference to FIG. 19.

Method 1700 then proceeds to step 1715 with monitoring the SRS resource for SRS transmitted in accordance with the activated or deactivated unified TCI state. In some cases, the operations of this step refer to, or may be performed by, circuitry for monitoring and/or code for monitoring as described with reference to FIG. 19.

In one aspect, method 1700, or any aspect related to it, may be performed by an apparatus, such as communications device 1900 of FIG. 19, which includes various components operable, configured, or adapted to perform the method 1700. Communications device 1900 is described below in further detail.

Note that FIG. 17 is just one example of a method, and other methods including fewer, additional, or alternative steps are possible consistent with this disclosure.

Example Communications Devices

FIG. 18 depicts aspects of an example communications device 1800. In some aspects, communications device 1800 is a user equipment, such as UE 104 described above with respect to FIGS. 1 and 3.

The communications device 1800 includes a processing system 1805 coupled to the transceiver 1845 (e.g., a transmitter and/or a receiver) . The transceiver 1845 is configured to transmit and receive signals for the communications device 1800 via the antenna 1850, such as the various signals as described herein. The processing system 1805 may be configured to perform processing functions for the communications device 1800, including processing signals received and/or to be transmitted by the communications device 1800.

The processing system 1805 includes one or more processors 1810. In various aspects, the one or more processors 1810 may be representative of one or more of receive processor 358, transmit processor 364, TX MIMO processor 366, and/or controller/processor 380, as described with respect to FIG. 3. The one or more processors 1810 are coupled to a computer-readable medium/memory 1825 via a bus 1840. In certain aspects, the computer-readable medium/memory 1825 is configured to store instructions (e.g., computer-executable code) that when executed by the one or more processors 1810, cause the one or more processors 1810 to perform the method 1600 described with respect to FIG. 16, or any aspect related to it. Note that reference to a processor performing a function of communications device 1800 may include one or more processors 1810 performing that function of communications device 1800.

In the depicted example, computer-readable medium/memory 1825 stores code (e.g., executable instructions) , such as code for obtaining 1830 and code for outputting 1835. Processing of the code for obtaining 1830 and code for outputting 1835 may cause the communications device 1800 to perform the method 1600 described with respect to FIG. 16, or any aspect related to it.

The one or more processors 1810 include circuitry configured to implement (e.g., execute) the code stored in the computer-readable medium/memory 1825, including circuitry such as circuitry for obtaining 1815 and circuitry for outputting 1820. Processing with circuitry for obtaining 1815 and circuitry for outputting 1820 may cause the communications device 1800 to perform the method 1600 described with respect to FIG. 16, or any aspect related to it.

Various components of the communications device 1800 may provide means for performing the method 1600 described with respect to FIG. 16, or any aspect related to it. For example, means for transmitting, sending or outputting for transmission may include transceivers 354 and/or antenna (s) 352 of the UE 104 illustrated in FIG. 3 and/or the transceiver 1845 and the antenna 1850 of the communications device 1800 in FIG. 18. Means for receiving or obtaining may include transceivers 354 and/or antenna (s) 352 of the UE 104 illustrated in FIG. 3 and/or the transceiver 1845 and the antenna 1850 of the communications device 1800 in FIG. 18.

FIG. 19 depicts aspects of an example communications device 1900. In some aspects, communications device 1900 is a network entity, such as BS 102 of FIGS. 1 and 3, or a disaggregated base station as discussed with respect to FIG. 2.

The communications device 1900 includes a processing system 1905 coupled to the transceiver 1945 (e.g., a transmitter and/or a receiver) and/or a network interface 1955. The transceiver 1945 is configured to transmit and receive signals for the communications device 1900 via the antenna 1950, such as the various signals as described herein. The network interface 1955 is configured to obtain and send signals for the communications device 1900 via communication link (s) , such as a backhaul link, midhaul link, and/or fronthaul link as described herein, such as with respect to FIG. 2. The processing system 1905 may be configured to perform processing functions for the communications device 1900, including processing signals received and/or to be transmitted by the communications device 1900.

The processing system 1905 includes one or more processors 1910. In various aspects, one or more processors 1910 may be representative of one or more of receive processor 338, transmit processor 320, TX MIMO processor 330, and/or controller/processor 340, as described with respect to FIG. 3. The one or more processors 1910 are coupled to a computer-readable medium/memory 1925 via a bus 1940. In certain aspects, the computer-readable medium/memory 1925 is configured to store instructions (e.g., computer-executable code) that when executed by the one or more processors 1910, cause the one or more processors 1910 to perform the method 1700 described with respect to FIG. 17, or any aspect related to it. Note that reference to a processor of communications device 1900 performing a function may include one or more processors 1910 of communications device 1900 performing that function.

In the depicted example, the computer-readable medium/memory 1925 stores code (e.g., executable instructions) , such as code for outputting 1930 and code for monitoring 1935. Processing of the code for outputting 1930 and code for monitoring 1935 may cause the communications device 1900 to perform the method 1700 described with respect to FIG. 17, or any aspect related to it.

The one or more processors 1910 include circuitry configured to implement (e.g., execute) the code stored in the computer-readable medium/memory 1925, including circuitry such as circuitry for outputting 1915 and circuitry for monitoring 1920. Processing with circuitry for outputting 1915 and circuitry for monitoring 1920 may cause the communications device 1900 to perform the method 1700 as described with respect to FIG. 17, or any aspect related to it.

Various components of the communications device 1900 may provide means for performing the method 1700 as described with respect to FIG. 17, or any aspect related to it. Means for transmitting, sending or outputting for transmission may include transceivers 332 and/or antenna (s) 334 of the BS 102 illustrated in FIG. 3 and/or the transceiver 1945 and the antenna 1950 of the communications device 1900 in FIG. 19. Means for receiving or obtaining may include transceivers 332 and/or antenna (s) 334 of the BS 102 illustrated in FIG. 3 and/or the transceiver 1945 and the antenna 1950 of the communications device 1900 in FIG. 19.

Example Clauses

Implementation examples are described in the following numbered clauses:

Clause 1: A method for wireless communications at a UE, comprising: obtaining first signaling configuring the UE with at least one of a SRS resource set or one or more unified TCI states for a SRS; obtaining second signaling activating or deactivating at least one of the unified TCI states for at least one SRS resource in the SRS resource set; and outputting, for transmission, the SRS via the SRS resource in accordance with the activated or deactivated unified TCI state.

Clause 2: The method of Clause 1, wherein the first signaling indicates a plurality of SRS resource sets including the SRS resource set, each SRS resource set including one or more SRS resources.

Clause 3: The method of any one of

Clauses

1 and 2, wherein each of the unified TCI states indicates a common beam associated with multiple signals.

Clause 4: The method of any one of Clauses 1-3, wherein: the first signaling comprises RRC signaling; and the second signaling comprises a MAC-CE.

Clause 5: The method of Clause 4, wherein the MAC CE includes at least one of: a first field indicating whether to activate or deactivate the SRS resource set; a second field indicating a cell ID for the SRS resource set or for an SRS resource in the SRS resource set; or a third field indicating a bandwidth part ID for the SRS resource set or for an SRS resource in the SRS resource set.

Clause 6: The method of Clause 4, wherein: the SRS resource set is configured as a semi-persistent or aperiodic SRS resource set; and the first signaling configures the SRS resource set with a configuration that includes a parameter indicating the SRS resource set is to follow a unified TCI state.

Clause 7: The method of Clause 4, wherein the MAC CE lacks an indication of the activated or deactivated unified TCI state.

Clause 8: The method of any one of Clauses 1-7, wherein: the SRS resource set is configured as a semi-persistent or aperiodic SRS resource set; and the first signaling configures the SRS resource set with a configuration that lacks a parameter indicating the SRS resource set is to follow a unified TCI state.

Clause 9: The method of Clause 8, wherein the MAC CE includes, for one or more SRS resources in the SRS resource set: an ID for the unified TCI state; and an indication of whether the unified TCI state is for: a joint TCI state that indicates a common beam for at least one downlink signal and at least one uplink signal, or an uplink TCI state that indicates a common beam for multiple uplink signals.

Clause 10: The method of Clause 8, wherein the MAC CE includes, for one or more SRS resources in the SRS resource set: an ID for the unified TCI state.

Clause 11: The method of any one of Clauses 1-10, wherein the first signaling configures each of the one or more unified TCI states for SRS as: a joint TCI state that indicates a common beam for at least one downlink signal and at least one uplink signal; or an uplink TCI state that indicates a common beam for multiple uplink signals.

Clause 12: A method for wireless communications at a network entity, comprising: outputting, for transmission, first signaling configuring a UE with at least one of a SRS resource set or one or more unified TCI states for a SRS; outputting, for transmission, second signaling activating or deactivating at least one of the unified TCI states for at least one SRS resource in the SRS resource set; and monitoring the SRS resource for SRS transmitted in accordance with the activated or deactivated unified TCI state.

Clause 13: The method of Clause 12, wherein the first signaling indicates a plurality of SRS resource sets including the SRS resource set, each SRS resource set including one or more SRS resources.

Clause 14: The method of any one of

Clauses

12 and 13, wherein each of the unified TCI states indicates a common beam associated with multiple signals.

Clause 15: The method of any one of Clauses 12-14, wherein: the first signaling comprises RRC signaling; and the second signaling comprises a MAC-CE.

Clause 16: The method of Clause 15, wherein the MAC CE includes at least one of: a first field indicating whether to activate or deactivate the SRS resource set; a second field indicating a cell ID for the SRS resource set or for an SRS resource in the SRS resource set; or a third field indicating a bandwidth part ID for the SRS resource set or for an SRS resource in the SRS resource set.

Clause 17: The method of Clause 15, wherein: the SRS resource set is configured as a semi-persistent or aperiodic SRS resource set; and the first signaling configures the SRS resource set with a configuration that includes a parameter indicating the SRS resource set is to follow a unified TCI state.

Clause 18: The method of Clause 15, wherein the MAC CE lacks an indication of the activated or deactivated unified TCI state.

Clause 19: The method of any one of Clauses 12-18, wherein: the SRS resource set is configured as a semi-persistent or aperiodic SRS resource set; and the first signaling configures the SRS resource set with a configuration that lacks a parameter indicating the SRS resource set is to follow a unified TCI state.

Clause 20: The method of Clause 19, wherein the MAC CE includes, for one or more SRS resources in the SRS resource set: an ID for the unified TCI state; and an indication of whether the unified TCI state is for: a joint TCI state that indicates a common beam for at least one downlink signal and at least one uplink signal, or an uplink TCI state that indicates a common beam for multiple uplink signals.

Clause 21: The method of Clause 19, wherein the MAC CE includes, for one or more SRS resources in the SRS resource set: an ID for the unified TCI state.

Clause 22: The method of any one of Clauses 12-21, wherein the first signaling configures each of the one or more unified TCI states for SRS as: a joint TCI state that indicates a common beam for at least one downlink signal and at least one uplink signal; or an uplink TCI state that indicates a common beam for multiple uplink signals.

Clause 23: An apparatus, comprising: a memory comprising instructions; and one or more processors configured to execute the instructions and cause the apparatus to perform a method in accordance with any one of Clauses 1-22.

Clause 24: An apparatus, comprising means for performing a method in accordance with any one of Clauses 1-22.

Clause 25: A non-transitory computer-readable medium comprising executable instructions that, when executed by a processor of an apparatus, cause the apparatus to perform a method in accordance with any one of Clauses 1-22.

Clause 26: A computer program product embodied on a computer-readable storage medium comprising code for performing a method in accordance with any one of Clauses 1-22.

Clause 27: A user equipment (UE) , comprising: at least one transceiver; a memory comprising instructions; and one or more processors configured to execute the instructions and cause the UE to perform a method in accordance with any one of Clause 1-11, wherein the at least one transceiver is configured to at least one of receive the first signaling, receive the second signaling, or transmit the SRS.

Clause 28: A network entity, comprising: at least one transceiver; a memory comprising instructions; and one or more processors configured to execute the instructions and cause the network entity to perform a method in accordance with any one of Clause 12-24, wherein the at least one transceiver is configured to at least one of transmit the first signaling, transmit the second signaling, or receive the SRS.

Additional Considerations

The preceding description is provided to enable any person skilled in the art to practice the various aspects described herein. The examples discussed herein are not limiting of the scope, applicability, or aspects set forth in the claims. 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. For example, changes may be made in the function and arrangement of elements discussed without departing from the scope of the disclosure. Various examples may omit, substitute, or add various procedures or components as appropriate. For instance, the methods described may be performed in an order different from that described, and various actions may be added, omitted, or combined. Also, features described with respect to some examples may be combined in some other examples. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such an apparatus or method that is practiced using other structure, functionality, or structure and functionality in addition to, or other than, the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim.

The various illustrative logical blocks, modules and circuits described in connection with the present disclosure may be implemented or performed with a general purpose processor, a digital signal processor (DSP) , an ASIC, a field programmable gate array (FPGA) or other programmable logic device (PLD) , discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any commercially available processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, a system on a chip (SoC) , or any other such configuration.

As used herein, a phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination with multiples of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c) .

As used herein, the term “determining” encompasses a wide variety of actions. For example, “determining” may include calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, a database or another data structure) , ascertaining and the like. Also, “determining” may include receiving (e.g., receiving information) , accessing (e.g., accessing data in a memory) and the like. Also, “determining” may include resolving, selecting, choosing, establishing and the like.

The methods disclosed herein comprise one or more actions for achieving the methods. The method actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of actions is specified, the order and/or use of specific actions may be modified without departing from the scope of the claims. Further, the various operations of methods described above may be performed by any suitable means capable of performing the corresponding functions. The means may include various hardware and/or software component (s) and/or module (s) , including, but not limited to a circuit, an application specific integrated circuit (ASIC) , or processor.

The following claims are not intended to be limited to the aspects shown herein, but are to be accorded the full scope consistent with the language of the claims. Within a claim, reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more. ” Unless specifically stated otherwise, the term “some” refers to one or more. No claim element is to be construed under the provisions of 35 U.S.C. §112 (f) unless the element is expressly recited using the phrase “means for” . All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be 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 intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims.

Claims

An apparatus for wireless communications, comprising:

a memory comprising instructions; and

one or more processors configured to execute the instructions and cause the apparatus to:

obtain first signaling configuring the apparatus with at least one of a sounding reference signal (SRS) resource set or one or more unified Transmission Configuration Indicator (TCI) states for a SRS;

obtain second signaling activating or deactivating at least one of the unified TCI states for at least one SRS resource in the SRS resource set; and

output, for transmission, the SRS via the SRS resource in accordance with the activated or deactivated unified TCI state.
The apparatus of claim 1, wherein the first signaling indicates a plurality of SRS resource sets including the SRS resource set, each SRS resource set including one or more SRS resources.
The apparatus of claim 1, wherein each of the unified TCI states indicates a common beam associated with multiple signals.
The apparatus of claim 1, wherein:

the first signaling comprises radio resource control (RRC) signaling; and

the second signaling comprises a medium access control (MAC) control element (CE) .
The apparatus of claim 1, wherein:

the SRS resource set is configured as a semi-persistent or aperiodic SRS resource set; and

the first signaling configures the SRS resource set with a configuration that lacks a parameter indicating the SRS resource set is to follow a unified TCI state.
The apparatus of claim 4, wherein the MAC CE includes at least one of:

a first field indicating whether to activate or deactivate the SRS resource set;

a second field indicating a cell ID for the SRS resource set or for an SRS resource in the SRS resource set; or

a third field indicating a bandwidth part ID for the SRS resource set or for an SRS resource in the SRS resource set.
The apparatus of claim 5, wherein the MAC CE includes, for one or more SRS resources in the SRS resource set:

an ID for the unified TCI state; and

an indication of whether the unified TCI state is for:

a joint TCI state that indicates a common beam for at least one downlink signal and at least one uplink signal, or

an uplink TCI state that indicates a common beam for multiple uplink signals.
The apparatus of claim 5, wherein the MAC CE includes, for one or more SRS resources in the SRS resource set:

an ID for the unified TCI state.
The apparatus of claim 1, wherein the first signaling configures each of the one or more unified TCI states for SRS as:

a joint TCI state that indicates a common beam for at least one downlink signal and at least one uplink signal; or

an uplink TCI state that indicates a common beam for multiple uplink signals.
The apparatus of claim 4, wherein:

the SRS resource set is configured as a semi-persistent or aperiodic SRS resource set; and

the first signaling configures the SRS resource set with a configuration that includes a parameter indicating the SRS resource set is to follow a unified TCI state.
The apparatus of claim 4, wherein the MAC CE lacks an indication of the activated or deactivated unified TCI state.
The apparatus of claim 1, further comprising at least one transceiver configured to at least one of receive the first signaling, receive the second signaling, or transmit the SRS, wherein the apparatus is configured as a user equipment (UE) .
A apparatus for wireless communications at a network entity, comprising:

outputting, for transmission, first signaling configuring a user equipment (UE) with at least one of a sounding reference signal (SRS) resource set or one or more unified Transmission Configuration Indicator (TCI) states for a SRS;

outputting, for transmission, second signaling activating or deactivating at least one of the unified TCI states for at least one SRS resource in the SRS resource set; and

monitoring the SRS resource for SRS transmitted in accordance with the activated or deactivated unified TCI state.
The apparatus of claim 13, wherein the first signaling indicates a plurality of SRS resource sets including the SRS resource set, each SRS resource set including one or more SRS resources.
The apparatus of claim 13, wherein each of the unified TCI states indicates a common beam associated with multiple signals.
The apparatus of claim 13, wherein:

the first signaling comprises radio resource control (RRC) signaling; and

the second signaling comprises a medium access control (MAC) control element (CE) .
The apparatus of claim 13, wherein:

the SRS resource set is configured as a semi-persistent or aperiodic SRS resource set; and

the first signaling configures the SRS resource set with a configuration that lacks a parameter indicating the SRS resource set is to follow a unified TCI state.
The apparatus of claim 16, wherein the MAC CE includes at least one of:

a first field indicating whether to activate or deactivate the SRS resource set;

a second field indicating a cell ID for the SRS resource set or for an SRS resource in the SRS resource set; or

a third field indicating a bandwidth part ID for the SRS resource set or for an SRS resource in the SRS resource set.
The apparatus of claim 17, wherein the MAC CE includes, for one or more SRS resources in the SRS resource set:

an ID for the unified TCI state; and

an indication of whether the unified TCI state is for:

a joint TCI state that indicates a common beam for at least one downlink signal and at least one uplink signal, or

an uplink TCI state that indicates a common beam for multiple uplink signals.
The apparatus of claim 17, wherein the MAC CE includes, for one or more SRS resources in the SRS resource set:

an ID for the unified TCI state.
The apparatus of claim 13, wherein the first signaling configures each of the one or more unified TCI states for SRS as:

a joint TCI state that indicates a common beam for at least one downlink signal and at least one uplink signal; or

an uplink TCI state that indicates a common beam for multiple uplink signals.
The apparatus of claim 16, wherein:

the SRS resource set is configured as a semi-persistent or aperiodic SRS resource set; and

the first signaling configures the SRS resource set with a configuration that includes a parameter indicating the SRS resource set is to follow a unified TCI state.
The apparatus of claim 16, wherein the MAC CE lacks an indication of the activated or deactivated unified TCI state.
The apparatus of claim 13, further comprising at least one transceiver configured to at least one of transmit the first signaling, transmit the second signaling, or receive the SRS, wherein the apparatus is configured as a network entity.