Patent Publication Number: US-11647530-B2

Title: Transmission configuration indicator (TCI) state groups

Description:
INTRODUCTION 
     The technology discussed below relates generally to wireless communication networks, and more particularly, to beam configuration in beam-based communication scenarios. 
     In wireless communication systems, such as those specified under standards for 5G New Radio (NR), a base station and user equipment (UE) may utilize beamforming for spatial division multiplexing of multiple streams from the base station to the UE. To facilitate beamformed multi-stream communication, the base station may provide the UE with a set of transmission configuration indicator (TCI) states. Each TCI state may include quasi co-location (QCL) information indicating one or more downlink reference signals from which various radio channel properties of downlink channels or downlink signals may be inferred. An example of QCL information includes QCL-TypeD, which indicates a spatial property of a beam (e.g., a beam direction and/or beam width) associated with a particular downlink reference signal. From the QCL-TypeD information, the UE may infer the beam on which a downlink channel or downlink signal may be communicated. 
     TCI states may be activated or deactivated for a UE. The base station may then select a particular one of the activated TCI states for communication of a downlink channel or downlink signal to the UE. For multi-stream communication, a different TCI state can be selected for each of the streams, and each TCI state may be associated with a different transmission and reception point (TRP) associated with the base station. 
     BRIEF SUMMARY 
     The following presents a summary of one or more aspects of the present disclosure, in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated features of the disclosure and is intended neither to identify key or critical elements of all aspects of the disclosure nor to delineate the scope of any or all aspects of the disclosure. Its sole purpose is to present some concepts of one or more aspects of the disclosure in a form as a prelude to the more detailed description that is presented later. 
     In one example, a method for wireless communication at a user equipment (UE) in a wireless communication network is disclosed. The method can include obtaining a respective beam quality metric for each transmit beam of a plurality of transmit beams and transmitting, to a radio access network (RAN) entity, a beam report indicating a plurality of beam groups based on the respective beam quality metrics. Each of the plurality of beam groups can include two or more of the plurality of transmit beams. The method can further include receiving, from the RAN entity, a plurality of transmission configuration indicator (TCI) state groups, each of the plurality of TCI state groups corresponding to a respective one of the plurality of beam groups. 
     Another example provides a UE configured for wireless communication including a memory and a processor coupled to the memory. The processor and the memory can be configured to obtain a respective beam quality metric for each transmit beam of a plurality of transmit beams and transmit, to a radio access network (RAN) entity, a beam report indicating a plurality of beam groups based on the respective beam quality metrics. Each of the plurality of beam groups can include two or more of the plurality of transmit beams. The processor and the memory can further be configured to receive, from the RAN entity, a plurality of transmission configuration indicator (TCI) state groups, each of the plurality of TCI state groups corresponding to a respective one of the plurality of beam groups. 
     Another example provides a UE configured for wireless communication. The UE includes means for obtaining a respective beam quality metric for each transmit beam of a plurality of transmit beams and means for transmitting, to a radio access network (RAN) entity, a beam report indicating a plurality of beam groups based on the respective beam quality metrics. Each of the plurality of beam groups can include two or more of the plurality of transmit beams. The UE can further include means for receiving, from the RAN entity, a plurality of transmission configuration indicator (TCI) state groups, each of the plurality of TCI state groups corresponding to a respective one of the plurality of beam groups. 
     Another example provides a non-transitory computer-readable medium storing processor-executable code for causing a processor of a UE to obtain a respective beam quality metric for each transmit beam of a plurality of transmit beams and transmit, to a radio access network (RAN) entity, a beam report indicating a plurality of beam groups based on the respective beam quality metrics. Each of the plurality of beam groups can include two or more of the plurality of transmit beams. The non-transitory computer-readable medium can further include processor-executable code for causing the processor of the UE to receive, from the RAN entity, a plurality of transmission configuration indicator (TCI) state groups, each of the plurality of TCI state groups corresponding to a respective one of the plurality of beam groups. 
     In another example, a method for wireless communication at a radio access network (RAN) entity in a wireless communication network is disclosed. The method can include receiving, from a user equipment (UE) in wireless communication with the RAN entity, a beam report indicating a plurality of beam groups, each including two or more of a plurality of transmit beams associated with the RAN entity. The method can further include grouping the plurality of transmit beams into the plurality of beam groups based on the beam report. The method can further include transmitting, to the UE, a plurality of transmission configuration indicator (TCI) state groups, each of the plurality of TCI state groups corresponding to a respective one of the plurality of beam groups. 
     Another example provides a RAN entity configured for wireless communication including a memory and a processor coupled to the memory. The processor and the memory can be configured to receive, from a user equipment (UE) in wireless communication with the RAN entity, a beam report indicating a plurality of beam groups, each including two or more of a plurality of transmit beams associated with the RAN entity. The processor and the memory can further be configured to group the plurality of transmit beams into the plurality of beam groups based on the beam report. The processor and the memory can further be configured to transmit, to the UE, a plurality of transmission configuration indicator (TCI) state groups, each of the plurality of TCI state groups corresponding to a respective one of the plurality of beam groups. 
     Another example provides a RAN entity configured for wireless communication. The RAN entity can include means for receiving, from a user equipment (UE) in wireless communication with the RAN entity, a beam report indicating a plurality of beam groups, each including two or more of a plurality of transmit beams associated with the RAN entity. The RAN entity can further include means for grouping the plurality of transmit beams into the plurality of beam groups based on the beam report. The RAN entity can further include means for transmitting, to the UE, a plurality of transmission configuration indicator (TCI) state groups, each of the plurality of TCI state groups corresponding to a respective one of the plurality of beam groups. 
     Another example provides a non-transitory computer-readable medium storing processor-executable code for causing a processor of a RAN entity to receive, from a user equipment (UE) in wireless communication with the RAN entity, a beam report indicating a plurality of beam groups, each including two or more of a plurality of transmit beams associated with the RAN entity. The non-transitory computer-readable medium can further include processor-executable code for causing the processor of the RAN entity to group the plurality of transmit beams into the plurality of beam groups based on the beam report. The non-transitory computer-readable medium can further include processor-executable code for causing the processor of the RAN entity to transmit, to the UE, a plurality of transmission configuration indicator (TCI) state groups, each of the plurality of TCI state groups corresponding to a respective one of the plurality of beam groups. 
     These and other aspects will become more fully understood upon a review of the detailed description, which follows. Other aspects, features, and examples will become apparent to those of ordinary skill in the art, upon reviewing the following description of specific, exemplary aspects of in conjunction with the accompanying figures. While features may be discussed relative to certain aspects and figures below, all aspects can include one or more of the advantageous features discussed herein. In other words, while one or more aspects may be discussed as having certain advantageous features, one or more of such features may also be used in accordance with the various aspects discussed herein. In similar fashion, while exemplary aspects may be discussed below as device, system, or method aspects, such exemplary aspects can be implemented in various devices, systems, and methods. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a conceptual illustration of an example of a radio access network according to some aspects. 
         FIG.  2    is a diagram illustrating an example of a frame structure for use in a radio access network according to some aspects. 
         FIG.  3    is a block diagram illustrating a wireless communication system supporting beamforming and/or multiple-input multiple-output (MIMO) communication according to some aspects. 
         FIG.  4    is a diagram illustrating an example of beamforming in a multi-TRP environment according to some aspects. 
         FIG.  5    is a diagram illustrating an example of multi-stream communication according to some aspects. 
         FIG.  6    is a diagram illustrating an example of TCI state group configuration for multi-stream communication according to some aspects. 
         FIG.  7    is a diagram illustrating an example of beam quality metric vectors obtained during the beam management procedure of  FIG.  6    according to some aspects. 
         FIG.  8    is a signaling diagram illustrating an exemplary TCI state management procedure according to some aspects. 
         FIG.  9    is a signaling diagram illustrating another exemplary TCI state management procedure for multi-stream communication according to some aspects. 
         FIGS.  10 A and  10 B  are diagrams illustrating examples of a beam report including an indication of beam groups according to some aspects. 
         FIGS.  11 A and  11 B  are diagrams illustrating examples of radio resource control (RRC) TCI state tables according to some aspects. 
         FIG.  12    is a block diagram illustrating an example of a hardware implementation for a UE employing a processing system according to some aspects. 
         FIG.  13    is a flow chart of an exemplary method for TCI state group management for multi-stream communication at a UE according to some aspects. 
         FIG.  14    is a flow chart of another exemplary method for TCI state management for multi-stream communication at a UE according to some aspects. 
         FIG.  15    is a block diagram illustrating an example of a hardware implementation for a radio access network (RAN) entity employing a processing system according to some aspects. 
         FIG.  16    is a flow chart of an exemplary method for TCI state management for multi-stream communication at a RAN entity according to some aspects. 
         FIG.  17    is a flow chart of another exemplary method for TCI state management for multi-stream communication at a RAN entity according to some aspects. 
     
    
    
     DETAILED DESCRIPTION 
     The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form in order to avoid obscuring such concepts. 
     The electromagnetic spectrum is often subdivided, based on frequency/wavelength, into various classes, bands, channels, etc. In 5G NR two initial operating bands have been identified as frequency range designations FR1 (410 MHz-7.125 GHz) and FR2 (24.25 GHz-52.6 GHz). It should be understood that although a portion of FR1 is greater than 6 GHz, FR1 is often referred to (interchangeably) as a “Sub-6 GHz” band in various documents and articles. A similar nomenclature issue sometimes occurs with regard to FR2, which is often referred to (interchangeably) as a “millimeter wave” band in documents and articles, despite being different from the extremely high frequency (EHF) band (30 GHz-300 GHz) which is identified by the International Telecommunications Union (ITU) as a “millimeter wave” band. 
     The frequencies between FR1 and FR2 are often referred to as mid-band frequencies. Recent 5G NR studies have identified an operating band for these mid-band frequencies as frequency range designation FR3 (7.125 GHz-24.25 GHz). Frequency bands falling within FR3 may inherit FR1 characteristics and/or FR2 characteristics, and thus may effectively extend features of FR1 and/or FR2 into mid-band frequencies. In addition, higher frequency bands are currently being explored to extend 5G NR operation beyond 52.6 GHz. For example, three higher operating bands have been identified as frequency range designations FR4-a or FR4-1 (52.6 GHz-71 GHz), FR4 (52.6 GHz-114.25 GHz), and FR5 (114.25 GHz-300 GHz). Each of these higher frequency bands falls within the EHF band. 
     With the above aspects in mind, unless specifically stated otherwise, it should be understood that the term “sub-6 GHz” or the like if used herein may broadly represent frequencies that may be less than 6 GHz, may be within FR1, or may include mid-band frequencies. Further, unless specifically stated otherwise, it should be understood that the term “millimeter wave” or the like if used herein may broadly represent frequencies that may include mid-band frequencies, may be within FR2, FR4, FR4-a or FR4-1, and/or FR5, or may be within the EHF band. 
     Various aspects of the disclosure relate to transmission configuration indicator (TCI) state configuration in multi-stream communication between a radio access network (RAN) entity and a user equipment (UE). The RAN entity may transmit a plurality of transmit beams in a mmWave frequency band (e.g., FR2, FR4, FR4-a, FR4-1, FR5 or other frequency band utilizing spatially directional beams), each carrying a respective beam reference signal (e.g., a synchronization signal block (SSB) or channel state information-reference signal (CSI-RS)) to the UE. The UE may obtain a respective beam quality metric (e.g., reference signal received power (RSRP), signal-to-interference-plus-noise ratio (SINR), etc.) for each of the transmit beams. The UE may then generate and transmit a beam report including the beam quality metrics for each of the transmit beams to the RAN entity. Based on the beam report, the RAN entity may group the transmit beams into beam groups and transmit a respective TCI state group for each of the beam groups to the UE. 
     In some examples, the RAN entity may transmit a radio resource control (RRC) configuration of the TCI state groups to the UE. For example, the RAN entity may configure an RRC TCI state group table for the UE based on the beam report and transmit the RRC TCI state group table to the UE. The RAN entity may then transmit an activation message, such as a medium access control-control element (MAC-CE), activating a set of active TCI state groups. In some examples, the set of active TCI state groups may include up to eight of the TCI state groups. To facilitate multi-stream communication of a physical downlink shared channel (PDSCH), the RAN entity may then transmit control information (e.g., downlink control information (DCI)) to the UE that includes an active TCI state group of the set of active TCI state groups associated with an assignment of resources for spatial division multiplexing (SDM) of a plurality of streams to the UE. In some examples, the control information may include three bits indicating the active TCI state group. 
     For example, each of the transmit beams associated with the RAN entity may correspond to a respective transmission and reception point (TRP) associated with the RAN entity. In this example, each of the streams in the multi-stream communication may be transmitted from a different one of the TRPs using an active beam group associated with the active TCI state group. 
     In some examples, the UE may further obtain a respective initial beam quality metric for each of the transmit beams and transmit an initial beam report including the respective initial beam quality metrics to the RAN entity. The RAN entity may then configure an RRC TCI states table for the UE based on the initial beam report and transmit to the UE a plurality of TCI states, each associated with a respective one of the plurality of transmit beams. For example, the RAN entity may transmit an RRC configuration of the plurality of TCI states (e.g., the RRC TCI states table) to the UE. Each of the plurality of TCI state groups may include the respective TCI states of each of the transmit beams within the respective beam group. 
     In some examples, for each transmit beam, the UE may obtain a respective individual beam quality metric on each receive beam of the UE during a measurement period to produce a respective beam quality metric vector. In some examples, the beam report may then include the beam quality metric vectors. In some examples, the beam report may include recommended beam groups. Here, the UE may utilize the beam quality metric vectors to identify the recommended beam groups and the RAN entity may group the transmit beams into the beam groups based on the recommended beam groups. 
     In some examples, for each transmit beam, the UE may measure each of the receive beams in parallel (e.g., at the same time) during the measurement period. For example, the UE may utilize a Butler matrix to perform the parallel measurements. In other examples, for each transmit beam, the UE may measure the respective beam quality metric on each of the receive beams serially (e.g., on one receive beam at a time) during the measurement period. Here, the serial measurements on each of the receive beams may be conducted on respective repetitions of the transmit beam, such that one measurement is obtained on each receive beam at a time using one of the repetitions of the transmit beam. In other examples, for each transmit beam, the UE may measure the respective beam quality metric on each of the receive beams in parallel for each of a plurality repetitions of the transmit beam during the measurement period to double the vector length. 
     In some examples, each of the beam report and the initial beam report are Layer 1 (L1) beam measurement reports in which the measurements are both performed at the physical layer (L1) and reported at the physical layer (L1). In some examples, the beam quality metric includes a reference signal received power (RSRP). In this example, the beam quality metric vectors can include RSRP vectors. In some examples, the RSRP vectors can indicate an inter-beam interference (or mutual interference) between the plurality of transmit beams. In this example, the beam groups may each include at least two beam pair links (e.g., pairs of transmit beams and corresponding receive beams) that may have a minimum mutual interference therebetween. 
     While aspects and features are described in this application by illustration to some examples, those skilled in the art will understand that additional implementations and use cases may come about in many different arrangements and scenarios. Aspects described herein may be implemented across many differing platform types, devices, systems, shapes, sizes, and packaging arrangements. For example, aspects and/or uses may come about via integrated chip devices and other non-module-component based devices (e.g., end-user devices, vehicles, communication devices, computing devices, industrial equipment, retail/purchasing devices, medical devices, AI-enabled devices, etc.). While some examples may or may not be specifically directed to use cases or applications, a wide assortment of applicability of described aspects may occur. Implementations may range in spectrum from chip-level or modular components to non-modular, non-chip-level implementations and further to aggregate, distributed, or OEM devices or systems incorporating one or more aspects of the described aspects. In some practical settings, devices incorporating described aspects and features may also necessarily include additional components and features for implementation and practice of claimed and described examples. For example, transmission and reception of wireless signals necessarily includes a number of components for analog and digital purposes (e.g., hardware components including antenna, RF-chains, power amplifiers, modulators, buffer, processor(s), interleaver, adders/summers, etc.). It is intended that aspects described herein may be practiced in a wide variety of devices, chip-level components, systems, distributed arrangements, end-user devices, etc. of varying sizes, shapes and constitution. 
     The various concepts presented throughout this disclosure may be implemented across a broad variety of telecommunication systems, network architectures, and communication standards. Referring now to  FIG.  1   , as an illustrative example without limitation, a schematic illustration of a radio access network  100  is provided. The RAN  100  may implement any suitable wireless communication technology or technologies to provide radio access. As one example, the RAN  100  may operate according to 3rd Generation Partnership Project (3GPP) New Radio (NR) specifications, often referred to as 5G. As another example, the RAN  100  may operate under a hybrid of 5G NR and Evolved Universal Terrestrial Radio Access Network (eUTRAN) standards, often referred to as LTE. The 3GPP refers to this hybrid RAN as a next-generation RAN, or NG-RAN. Of course, many other examples may be utilized within the scope of the present disclosure. 
     The geographic region covered by the radio access network  100  may be divided into a number of cellular regions (cells) that can be uniquely identified by a user equipment (UE) based on an identification broadcasted over a geographical area from one access point or base station.  FIG.  1    illustrates macrocells  102 ,  104 ,  106 ,  142 , and  146 , and a small cell  108 , each of which may include one or more sectors (not shown). A sector is a sub-area of a cell. All sectors within one cell are served by the same base station. A radio link within a sector can be identified by a single logical identification belonging to that sector. In a cell that is divided into sectors, the multiple sectors within a cell can be formed by groups of antennas with each antenna responsible for communication with UEs in a portion of the cell. 
     In general, a respective base station (BS) serves each cell. Broadly, a base station is a network element or entity in a radio access network responsible for radio transmission and reception in one or more cells to or from a UE. A BS may also be referred to by those skilled in the art as a base transceiver station (BTS), a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), an access point (AP), a Node B (NB), an eNode B (eNB), a gNode B (gNB), a transmission and reception point (TRP), or some other suitable terminology. 
     In  FIG.  1   , three base stations  110 ,  112 , and  114  are shown in cells  102 ,  104 , and  106 , respectively; and a fourth base station  116  is shown controlling remote radio heads (RRHs)  144  and  148  in cells  142  and  146 . That is, a base station can have an integrated antenna or can be connected to an antenna or RRH by feeder cables. In the illustrated example, the cells  102 ,  104 ,  106 ,  142 , and  146  may be referred to as macrocells, as the base stations  110 ,  112 ,  114 , and  116  support cells having a large size. Further, a base station  118  is shown in the small cell  108  (e.g., a microcell, picocell, femtocell, home base station, home Node B, home eNode B, etc.) which may overlap with one or more macrocells. In this example, the cell  108  may be referred to as a small cell, as the base station  118  supports a cell having a relatively small size. Cell sizing can be done according to system design as well as component constraints. It is to be understood that the radio access network  100  may include any number of wireless base stations and cells. Further, a relay node may be deployed to extend the size or coverage area of a given cell. The base stations  110 ,  112 ,  114 ,  116 , and  118  provide wireless access points to a core network for any number of mobile apparatuses. 
       FIG.  1    further includes an unmanned aerial vehicle (UAV)  120 , such as a quadcopter or drone, which may be configured to function as a base station. That is, in some examples, a cell may not necessarily be stationary, and the geographic area of the cell may move according to the location of a mobile base station such as the UAV  120 . 
     In general, base stations may include a backhaul interface for communication with a backhaul portion (not shown) of the network. The backhaul may provide a link between a base station and a core network (not shown), and in some examples, the backhaul may provide interconnection between the respective base stations. The core network may be a part of a wireless communication system and may be independent of the radio access technology used in the radio access network. Various types of backhaul interfaces may be employed, such as a direct physical connection, a virtual network, or the like using any suitable transport network. 
     The RAN  100  is illustrated supporting wireless communication for multiple mobile apparatuses. A mobile apparatus is commonly referred to as user equipment (UE) in standards and specifications promulgated by the 3rd Generation Partnership Project (3GPP), but may also be referred to by those skilled in the art as a mobile station (MS), a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal (AT), a mobile terminal, a wireless terminal, a remote terminal, a handset, a terminal, a user agent, a mobile client, a client, or some other suitable terminology. A UE may be an apparatus that provides a user with access to network services. 
     Within the present document, a “mobile” apparatus need not necessarily have a capability to move, and may be stationary. The term mobile apparatus or mobile device broadly refers to a diverse array of devices and technologies. For example, some non-limiting examples of a mobile apparatus include a mobile, a cellular (cell) phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a personal computer (PC), a notebook, a netbook, a smartbook, a tablet, a personal digital assistant (PDA), and a broad array of embedded systems, e.g., corresponding to an “Internet of things” (IoT). A mobile apparatus may additionally be an automotive or other transportation vehicle, a remote sensor or actuator, a robot or robotics device, a satellite radio, a global positioning system (GPS) device, an object tracking device, a drone, a multi-copter, a quad-copter, a remote control device, a consumer and/or wearable device, such as eyewear, a wearable camera, a virtual reality device, a smart watch, a health or fitness tracker, a digital audio player (e.g., MP3 player), a camera, a game console, etc. A mobile apparatus may additionally be a digital home or smart home device such as a home audio, video, and/or multimedia device, an appliance, a vending machine, intelligent lighting, a home security system, a smart meter, etc. A mobile apparatus may additionally be a smart energy device, a security device, a solar panel or solar array, a municipal infrastructure device controlling electric power (e.g., a smart grid), lighting, water, etc., an industrial automation and enterprise device, a logistics controller, agricultural equipment, etc. Still further, a mobile apparatus may provide for connected medicine or telemedicine support, i.e., health care at a distance. Telehealth devices may include telehealth monitoring devices and telehealth administration devices, whose communication may be prioritized access over other types of information, e.g., in terms of prioritized access for transport of critical service data, and/or relevant QoS for transport of critical service data. 
     Within the RAN  100 , the cells may include UEs that may be in communication with one or more sectors of each cell. For example, UEs  122  and  124  may be in communication with base station  110 ; UEs  126  and  128  may be in communication with base station  112 ; UEs  130  and  132  may be in communication with base station  114 ; UE  134  may be in communication with base station  118 ; UEs  138  and  140  may be in communication with base station  116  via one or more of the RRHs  144  and  148 ; and UE  136  may be in communication with mobile base station  120 . Here, each base station  110 ,  112 ,  114 ,  116 ,  118 , and  120  may be configured to provide an access point to a core network (not shown) for all the UEs in the respective cells. In another example, a mobile network node (e.g., UAV  120 ) may be configured to function as a UE. For example, the UAV  120  may operate within cell  102  by communicating with base station  110 . 
     In some examples, access to the air interface may be scheduled, wherein a scheduling entity (e.g., a base station  112 ) allocates resources for communication among some or all devices and equipment within its service area or cell. Within the present disclosure, as discussed further below, the scheduling entity may be responsible for scheduling, assigning, reconfiguring, and releasing resources for one or more scheduled entities. That is, for scheduled communication, UEs (e.g., UE  126 ), which may be scheduled entities, may utilize resources allocated by the scheduling entity  112 . 
     Base stations are not the only entities that may function as scheduling entities. That is, in some examples, a UE may function as a scheduling entity, scheduling resources for one or more scheduled entities (e.g., one or more other UEs). And as discussed more below, UEs may communicate directly with other UEs in peer-to-peer (P2P) fashion and/or in relay configuration. 
     In a further aspect of the RAN  100 , sidelink signals may be used between UEs without necessarily relying on scheduling or control information from a base station. For example, two or more UEs (e.g., UEs  126  and  128 ) may communicate with each other using peer to peer (P2P) or sidelink signals  127  without relaying that communication through a base station (e.g., base station  112 ). In some examples, the sidelink signals  127  include sidelink traffic and sidelink control. In some examples, the UEs  126  and  128  may each function as a scheduling entity and/or scheduled entity in which resources may be autonomously selected by the scheduling entity or initiating (e.g., transmitting) sidelink device for sidelink communication with the scheduled entity or receiving sidelink device. In other examples, the base station  112  may allocate resources to the UEs  126  and  128  for the sidelink communication. For example, the UEs  126  and  128  may function as scheduling entities or scheduled entities in a P2P network, a device-to-device (D2D), vehicle-to-vehicle (V2V) network, a vehicle-to-everything (V2X), a mesh network, or other suitable network. 
     In the RAN  100 , the ability for a UE to communicate while moving, independent of their location, is referred to as mobility. The various physical channels between the UE and the RAN are generally set up, maintained, and released under the control of an access and mobility management function (AMF), which may include a security context management function (SCMF) that manages the security context for both the control plane and the user plane functionality and a security anchor function (SEAF) that performs authentication. In some examples, during a call with a scheduling entity, or at any other time, a UE may monitor various parameters of the signal from its serving cell as well as various parameters of neighboring cells. Depending on the quality of these parameters, the UE may maintain communication with one or more of the neighboring cells. During this time, if the UE moves from one cell to another, or if signal quality from a neighboring cell exceeds that from the serving cell for a given amount of time, the UE may undertake a handoff or handover from the serving cell to the neighboring (target) cell. For example, UE  124  may move from the geographic area corresponding to its serving cell  102  to the geographic area corresponding to a neighbor cell  106 . When the signal strength or quality from the neighbor cell  106  exceeds that of its serving cell  102  for a given amount of time, the UE  124  may transmit a reporting message to its serving base station  110  indicating this condition. In response, the UE  124  may receive a handover command, and the UE may undergo a handover to the cell  106 . 
     Wireless communication between a RAN  100  and a UE (e.g., UE  122  or  124 ) may be described as utilizing an air interface. Transmissions over the air interface from a base station (e.g., base station  110 ) to one or more UEs (e.g., UE  122  and  124 ) may be referred to as downlink (DL) transmission. In accordance with certain aspects of the present disclosure, the term downlink may refer to a point-to-multipoint transmission originating at a scheduling entity (described further below; e.g., base station  110 ). Another way to describe this scheme may be to use the term broadcast channel multiplexing. Transmissions from a UE (e.g., UE  122 ) to a base station (e.g., base station  110 ) may be referred to as uplink (UL) transmissions. In accordance with further aspects of the present disclosure, the term uplink may refer to a point-to-point transmission originating at a scheduled entity (described further below; e.g., UE  122 ). 
     For example, DL transmissions may include unicast or broadcast transmissions of control information and/or data (e.g., user data traffic or other type of traffic) from a base station (e.g., base station  110 ) to one or more UEs (e.g., UEs  122  and  124 ), while UL transmissions may include transmissions of control information and/or traffic information originating at a UE (e.g., UE  122 ). In addition, the uplink and/or downlink control information and/or traffic information may be time-divided into frames, subframes, slots, and/or symbols. As used herein, a symbol may refer to a unit of time that, in an orthogonal frequency division multiplexed (OFDM) waveform, carries one resource element (RE) per sub-carrier. A slot may carry 7 or 14 OFDM symbols. A subframe may refer to a duration of 1 ms. Multiple subframes or slots may be grouped together to form a single frame or radio frame. Of course, these definitions are not required, and any suitable scheme for organizing waveforms may be utilized, and various time divisions of the waveform may have any suitable duration. 
     The air interface in the RAN  100  may utilize one or more multiplexing and multiple access algorithms to enable simultaneous communication of the various devices. For example, 5G NR specifications provide multiple access for UL or reverse link transmissions from UEs  122  and  124  to base station  110 , and for multiplexing DL or forward link transmissions from the base station  110  to UEs  122  and  124  utilizing orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP). In addition, for UL transmissions, 5G NR specifications provide support for discrete Fourier transform-spread-OFDM (DFT-s-OFDM) with a CP (also referred to as single-carrier FDMA (SC-FDMA)). However, within the scope of the present disclosure, multiplexing and multiple access are not limited to the above schemes, and may be provided utilizing time division multiple access (TDMA), code division multiple access (CDMA), frequency division multiple access (FDMA), sparse code multiple access (SCMA), resource spread multiple access (RSMA), or other suitable multiple access schemes. Further, multiplexing DL transmissions from the base station  110  to UEs  122  and  124  may be provided utilizing time division multiplexing (TDM), code division multiplexing (CDM), frequency division multiplexing (FDM), orthogonal frequency division multiplexing (OFDM), sparse code multiplexing (SCM), or other suitable multiplexing schemes. 
     Further, the air interface in the RAN  100  may utilize one or more duplexing algorithms Duplex refers to a point-to-point communication link where both endpoints can communicate with one another in both directions. Full-duplex means both endpoints can simultaneously communicate with one another. Half-duplex means only one endpoint can send information to the other at a time. Half-duplex emulation is frequently implemented for wireless links utilizing time division duplex (TDD). In TDD, transmissions in different directions on a given channel are separated from one another using time division multiplexing. That is, at some times the channel is dedicated for transmissions in one direction, while at other times the channel is dedicated for transmissions in the other direction, where the direction may change very rapidly, e.g., several times per slot. In a wireless link, a full-duplex channel generally relies on physical isolation of a transmitter and receiver, and suitable interference cancellation technologies. Full-duplex emulation is frequently implemented for wireless links by utilizing frequency division duplex (FDD) or spatial division duplex (SDD). In FDD, transmissions in different directions may operate at different carrier frequencies (e.g., within paired spectrum). In SDD, transmissions in different directions on a given channel are separated from one another using spatial division multiplexing (SDM). In other examples, full-duplex communication may be implemented within unpaired spectrum (e.g., within a single carrier bandwidth), where transmissions in different directions occur within different sub-bands of the carrier bandwidth. This type of full-duplex communication may be referred to herein as sub-band full duplex (SBFD), also known as flexible duplex. 
     In various implementations, the air interface in the RAN  100  may utilize licensed spectrum, unlicensed spectrum, or shared spectrum. Licensed spectrum provides for exclusive use of a portion of the spectrum, generally by virtue of a mobile network operator purchasing a license from a government regulatory body. Unlicensed spectrum provides for shared use of a portion of the spectrum without need for a government-granted license. While compliance with some technical rules is generally still required to access unlicensed spectrum, generally, any operator or device may gain access. Shared spectrum may fall between licensed and unlicensed spectrum, wherein technical rules or limitations may be required to access the spectrum, but the spectrum may still be shared by multiple operators and/or multiple RATs. For example, the holder of a license for a portion of licensed spectrum may provide licensed shared access (LSA) to share that spectrum with other parties, e.g., with suitable licensee-determined conditions to gain access. 
     In some examples, a UE (e.g., UE  138 ) may be in the coverage area of more than one cell (e.g., cells  142  and  146 ). In this example, each RRH  144  and  148  serving one of the cells  142  and  146  may function as a transmission and reception point (TRP) in a multi-TRP network configuration in which downlink and/or uplink signals may be transmitted between the UE  138  and each of the TRPs  144  and  148 . In some examples, the TRPs  144  and  148  may be configured using a centralized RAN architecture in which base station  116  operates to coordinate transmissions and receptions between the UE  138  and TRPs  144  and  148 . For example, the base station  116  and UE  138  may be configured for multi-stream communication, in which two streams of downlink data may be simultaneously transmitted to the UE  138  from each of the TRPs  144  and  148  to reduce interference, increase the data rate, and/or increase the received power. As another example, downlink signals may be transmitted from one TRP (e.g., TRP  144 ) and uplink signals may be received at another TRP (e.g., TRP  148 ). 
     In addition, beamformed signals may be utilized between the UE  138  and each of the TRPs  144  and  148  communicating, for example, over a mmWave carrier, such as FR2, FR4-a, FR4-1, FR4, or FR5. To facilitate beamformed multi-stream communication, the base station  116  may select a respective beam pair link (BPL) between the UE  138  and each of the TRPs  144  and  148  for spatial division multiplexing (SDM) of a respective stream on each of the BPLs. Each selected BPL may be associated with a respective transmission configuration indicator (TCI) state that indicates quasi co-location (QCL) information (e.g., QCL-Types) between a downlink reference signal, such as a synchronization signal block (SSB) or channel state information-reference signal (CSI-RS), and a downlink signal or downlink channel (e.g., a physical downlink shared channel) communicated on the selected BPL. 
     An example of QCL information includes QCL-TypeD, which indicates a spatial property of a beam (e.g., a beam direction and/or beam width) associated with a particular downlink reference signal. By indicating the QCL-TypeD information for a PDSCH transmission, the base station  116  may inform the UE  138  that the PDSCH transmission uses the same downlink (transmit) beam as a configured reference signal. In simple terms, it may be said that a TCI state can include a beam indication that explicitly identifies which downlink beam is being used by the base station  116 . 
     For multi-stream PDSCH communications, the base station  116  indicates the respective TCI state (e.g., respective beam) for each stream. The selected TCI states for a multi-stream PDSCH communication may be transmitted from the base station  116  to the UE  138  within, for example, control information (e.g., downlink control information (DCI)) that further carries the resource assignment (e.g., time-frequency resources) for the multi-stream PDSCH communication. For example, the selected TCI state for a particular stream may be signaled using three bits in the DCI. However, since the control information includes a separate selected TCI state for each stream, the signaling overhead increases linearly with the number of streams. 
     Therefore, in various aspects of the disclosure, the base station  116  and UE  138  may each include a respective TCI state manager  150  and  152  to enable TCI state groups to be configured on the base station  116  and UE  138 . Each TCI state group includes a plurality of (e.g., two or more) TCI states, each indicating a respective transmit (downlink) beam on which a corresponding stream of a multi-stream PDSCH communication is transmitted. In some examples, the TCI state manager  150  on the base station  116  may group various transmit beams of the TRPs  144  and  148  into a plurality of beam groups. Each beam group may include a single transmit beam from each of the TRPs  144  and  148  for multi-stream communication. The TCI state manager  150  on the base station  116  may then configure a plurality of TCI state groups for the UE  138 , each corresponding to a different respective beam group, and transmit the TCI state groups to the UE  138 . The TCI state groups may be configured, for example, based on a beam report received from the UE  138 . For example, the UE  138  may obtain a respective beam quality metric for each transmit beam from each TRP  114  and  148  and transmit the beam report indicating the beam groups based on the respective beam quality metrics. 
     In some examples, the TCI state manager  150  on the base station  116  may transmit a radio resource control (RRC) configuration of the plurality of TCI state groups (e.g., an RRC TCI state groups table) to the UE  138 . The RRC TCI state groups table may include a respective TCI state group identifier and a list of the TCI states included within the respective TCI state group for each of the TCI state groups. The TCI state manager  152  on the UE  138  may then store the RRC TCI state groups table for use in receiving a subsequent multi-stream communication. In some examples, the TCI state manager  150  on the base station  116  may further transmit an activation message (e.g., a MAC-CE) to the UE that activates a set of active TCI state groups of the plurality of TCI state groups. The TCI state manager  152  on the UE  138  may further store the set of active TCI state groups. For a multi-stream PDSCH communication, the TCI state manager  150  on the base station  116  may then select one of the active TCI state groups for transmission of the multi-stream PDSCH communication and include the selected active TCI state group in the control information (e.g., DCI) scheduling the multi-stream PDSCH communication. 
     Various aspects of the present disclosure will be described with reference to an OFDM waveform, schematically illustrated in  FIG.  2   . It should be understood by those of ordinary skill in the art that the various aspects of the present disclosure may be applied to an SC-FDMA waveform in substantially the same way as described herein below. That is, while some examples of the present disclosure may focus on an OFDM link for clarity, it should be understood that the same principles may be applied as well to SC-FDMA waveforms. 
     Referring now to  FIG.  2   , an expanded view of an exemplary DL subframe  202  is illustrated, showing an OFDM resource grid. However, as those skilled in the art will readily appreciate, the PHY transmission structure for any particular application may vary from the example described here, depending on any number of factors. Here, time is in the horizontal direction with units of OFDM symbols; and frequency is in the vertical direction with units of subcarriers. 
     The resource grid  204  may be used to schematically represent time-frequency resources for a given antenna port. That is, in a multiple-input-multiple-output (MIMO) implementation with multiple antenna ports available, a corresponding multiple number of resource grids  204  may be available for communication. The resource grid  204  is divided into multiple resource elements (REs)  206 . An RE, which is 1 subcarrier×1 symbol, is the smallest discrete part of the time-frequency grid, and contains a single complex value representing data from a physical channel or signal. Depending on the modulation utilized in a particular implementation, each RE may represent one or more bits of information. In some examples, a block of REs may be referred to as a physical resource block (PRB) or a resource block (RB)  208 , which contains any suitable number of consecutive subcarriers in the frequency domain. In one example, an RB may include 12 subcarriers, a number independent of the numerology used. In some examples, depending on the numerology, an RB may include any suitable number of consecutive OFDM symbols in the time domain. Within the present disclosure, it is assumed that a single RB such as the RB  208  entirely corresponds to a single direction of communication (either transmission or reception for a given device). 
     Scheduling of UEs or sidelink devices (hereinafter collectively referred to as UEs) for downlink, uplink, or sidelink transmissions typically involves scheduling one or more resource elements  206  within one or more sub-bands or bandwidth parts (BWPs). Thus, a UE generally utilizes only a subset of the resource grid  204 . In some examples, an RB may be the smallest unit of resources that can be allocated to a UE. Thus, the more RBs scheduled for a UE, and the higher the modulation scheme chosen for the air interface, the higher the data rate for the UE. The RBs may be scheduled by a base station (e.g., gNB, eNB, etc.) or may be self-scheduled by a UE/sidelink device implementing D2D sidelink communication. 
     In this illustration, the RB  208  is shown as occupying less than the entire bandwidth of the subframe  202 , with some subcarriers illustrated above and below the RB  208 . In a given implementation, the subframe  202  may have a bandwidth corresponding to any number of one or more RBs  208 . Further, in this illustration, the RB  208  is shown as occupying less than the entire duration of the subframe  202 , although this is merely one possible example. 
     Each 1 ms subframe  202  may consist of one or multiple adjacent slots. In the example shown in  FIG.  2   , one subframe  202  includes four slots  210 , as an illustrative example. In some examples, a slot may be defined according to a specified number of OFDM symbols with a given cyclic prefix (CP) length. For example, a slot may include 7 or 14 OFDM symbols with a nominal CP. Additional examples may include mini-slots, sometimes referred to as shortened transmission time intervals (TTIs), having a shorter duration (e.g., one to three OFDM symbols). These mini-slots or shortened transmission time intervals (TTIs) may in some cases be transmitted occupying resources scheduled for ongoing slot transmissions for the same or for different UEs. Any number of resource blocks may be utilized within a subframe or slot. 
     An expanded view of one of the slots  210  illustrates the slot  210  including a control region  212  and a data region  214 . In general, the control region  212  may carry control channels, and the data region  214  may carry data channels. In the example shown in  FIG.  2   , the control region  212  may include downlink control information and the data region  214  may include downlink data channels or uplink data channels. Of course, a slot may contain all DL, all UL, or at least one DL portion and at least one UL portion. The structure illustrated in  FIG.  2    is merely exemplary in nature, and different slot structures may be utilized, and may include one or more of each of the control region(s) and data region(s). 
     Although not illustrated in  FIG.  2   , the various REs  206  within an RB  208  may be scheduled to carry one or more physical channels, including control channels, shared channels, data channels, etc. Other REs  206  within the RB  208  may also carry pilots or reference signals. These pilots or reference signals may provide for a receiving device to perform channel estimation of the corresponding channel, which may enable coherent demodulation/detection of the control and/or data channels within the RB  208 . 
     In some examples, the slot  210  may be utilized for broadcast or unicast communication. For example, a broadcast, multicast, or groupcast communication may refer to a point-to-multipoint transmission by one device (e.g., a base station, UE, or other similar device) to other devices. Here, a broadcast communication is delivered to all devices, whereas a multicast communication is delivered to multiple intended recipient devices. A unicast communication may refer to a point-to-point transmission by a one device to a single other device. 
     In an example of cellular communication over a cellular carrier via a Uu interface, for a DL transmission, the scheduling entity (e.g., a base station) may allocate one or more REs  206  (e.g., within the control region  212 ) to carry DL control information including one or more DL control channels, such as a physical downlink control channel (PDCCH), to one or more scheduled entities (e.g., UEs). The PDCCH carries downlink control information (DCI) including but not limited to power control commands (e.g., one or more open loop power control parameters and/or one or more closed loop power control parameters), scheduling information, a grant, and/or an assignment of REs for DL and UL transmissions. The PDCCH may further carry HARQ feedback transmissions such as an acknowledgment (ACK) or negative acknowledgment (NACK). HARQ is a technique well-known to those of ordinary skill in the art, wherein the integrity of packet transmissions may be checked at the receiving side for accuracy, e.g., utilizing any suitable integrity checking mechanism, such as a checksum or a cyclic redundancy check (CRC). If the integrity of the transmission is confirmed, an ACK may be transmitted, whereas if not confirmed, a NACK may be transmitted. In response to a NACK, the transmitting device may send a HARQ retransmission, which may implement chase combining, incremental redundancy, etc. 
     The base station may further allocate one or more REs  206  (e.g., in the control region  212  or the data region  214 ) to carry other DL signals, such as a demodulation reference signal (DMRS); a phase-tracking reference signal (PT-RS); a channel state information (CSI) reference signal (CSI-RS); and a synchronization signal block (SSB). SSBs may be broadcast at regular intervals based on a periodicity (e.g., 5, 10, 20, 40, 80, or 160 ms). An SSB includes a primary synchronization signal (PSS), a secondary synchronization signal (SSS), and a physical broadcast control channel (PBCH). A UE may utilize the PSS and SSS to achieve radio frame, subframe, slot, and symbol synchronization in the time domain, identify the center of the channel (system) bandwidth in the frequency domain, and identify the physical cell identity (PCI) of the cell. 
     The PBCH in the SSB may further include a master information block (MIB) that includes various system information, along with parameters for decoding a system information block (SIB). The SIB may be, for example, a SystemInformationType 1 (SIB1) that may include various additional system information. Examples of system information transmitted in the MIB may include, but are not limited to, a subcarrier spacing, system frame number, a configuration of a PDCCH control resource set (CORESET) (e.g., PDCCH CORESETO), and a search space for SIB1. Examples of additional system information transmitted in the SIB1 may include, but are not limited to, a random access search space, downlink configuration information, and uplink configuration information. The MIB and SIB1 together provide the minimum system information (SI) for initial access. 
     In an UL transmission, the scheduled entity (e.g., UE) may utilize one or more REs  206  (e.g., within the control region  212 , which may be at the end of the slot  210 ) to carry UL control information (UCI) including one or more UL control channels, such as a physical uplink control channel (PUCCH), to the scheduling entity. UCI may include a variety of packet types and categories. In some examples, the UCI may include a scheduling request (SR), i.e., request for the scheduling entity to schedule uplink transmissions. Here, in response to the SR transmitted on the UCI, the scheduling entity may transmit downlink control information (DCI) that may schedule resources for uplink packet transmissions. UCI may also include HARQ feedback, channel state feedback (CSF), such as a CSI report, or any other suitable UCI. The scheduled entity (e.g., UE) may further utilize one or more REs  206  (e.g., within the control region  212  and/or the data region  214 ) to transmit pilots, reference signals, and other information configured to enable or assist in decoding uplink data transmissions and/or in uplink beam management, such as one or more DMRSs and sounding reference signals (SRSs). 
     In addition to control information, one or more REs  206  (e.g., within the data region  214 ) may be allocated for data traffic. Such data traffic may be carried on one or more traffic channels, such as, for a DL transmission, a physical downlink shared channel (PDSCH); or for an UL transmission, a physical uplink shared channel (PUSCH). In some examples, one or more REs  206  within the data region  214  may be configured to carry other signals, such as one or more SIBs and DMRSs. 
     In an example of sidelink communication over a sidelink carrier via a PC5 interface, the control region  212  of the slot  210  may include a physical sidelink control channel (PSCCH) including sidelink control information (SCI) transmitted by an initiating (transmitting) sidelink device (e.g., V2X or other sidelink device) towards a set of one or more other receiving sidelink devices. The data region  214  of the slot  210  may include a physical sidelink shared channel (PSSCH) including sidelink data traffic transmitted by the initiating (transmitting) sidelink device within resources reserved over the sidelink carrier by the transmitting sidelink device via the SCI. Other information may further be transmitted over various REs  206  within slot  210 . For example, HARQ feedback information may be transmitted in a physical sidelink feedback channel (PSFCH) within the slot  210  from the receiving sidelink device to the transmitting sidelink device. In addition, one or more reference signals, such as a sidelink SSB and/or a sidelink CSI-RS, may be transmitted within the slot  210 . 
     For beamforming, one or more beam reference signals (e.g., SSBs and/or CSI-RSs) may be utilized with beam sweeping for beam selection and beam refinement. For example, a base station may beam sweep a set of SSBs forming a SSB burst (e.g., a set of SSBs transmitted in a 5 ms window) for wide beam selection. Each SSB may be transmitted in four symbols across 240 subcarriers in a slot. As another example, a base station may beam sweep a set of CSI-RSs for narrow beam refinement. Depending on the configured number of ports at the base station, a CSI-RS resource may start at any symbol of a slot and may occupy, for example, one, two or four symbols. In some examples, the narrow CSI-RS beams may be sub-beams of one or more previously selected wider SSB beams. A UE may obtain a beam quality metric (e.g., reference signal received power (RSRP) or signal-to-interference-plus-noise (SINR) of each of the SSB or CSI-RS beams and transmit a beam report (e.g., an L1 beam measurement report) to the base station including the beam quality metric of one or more of the SSB or CSI-RS beams. 
     In various aspects, multi-stream beamformed communication may be facilitated using TCI state groups. For example, a base station may transmit a plurality of TCI state groups  216  to a UE. Each TCI state group may include a plurality of (e.g., two or more) TCI states, each indicating a respective transmit (downlink) beam on which a corresponding stream of a multi-stream PDSCH communication may be transmitted from the base station to the UE. In some examples, the base station may transmit an RRC configuration of the plurality of TCI state groups (e.g., within the control region  212 ) to the UE. The base station may further transmit an activation message  218  (e.g., a MAC-CE within the data region  214 ) to the UE that activates a set of active TCI state groups. The base station may further select one of the active TCI state groups for transmission of a multi-stream PDSCH communication and include the selected active TCI state group in control information  220  (e.g., DCI) scheduling the multi-stream PDSCH communication. 
     These physical channels described above are generally multiplexed and mapped to transport channels for handling at the medium access control (MAC) layer. Transport channels carry blocks of information called transport blocks (TB). The transport block size (TBS), which may correspond to a number of bits of information, may be a controlled parameter, based on the modulation and coding scheme (MCS) and the number of RBs in a given transmission. 
     The channels or carriers described above in connection with  FIGS.  1  and  2    are not necessarily all of the channels or carriers that may be utilized between a scheduling entity and scheduled entities, and those of ordinary skill in the art will recognize that other channels or carriers may be utilized in addition to those illustrated, such as other traffic, control, and feedback channels. 
       FIG.  3    illustrates an example of a wireless communication system  300  supporting beamforming and/or MIMO. In a MIMO system, a transmitter  302  includes multiple transmit antennas  304  (e.g., N transmit antennas) and a receiver  306  includes multiple receive antennas  308  (e.g., M receive antennas). Thus, there are N×M signal paths  310  from the transmit antennas  304  to the receive antennas  308 . Each of the transmitter  302  and the receiver  306  may be implemented, for example, within a scheduling entity, a scheduled entity, or any other suitable wireless communication device. 
     The use of such multiple antenna technology enables the wireless communication system to exploit the spatial domain to support spatial multiplexing, beamforming, and transmit diversity. Spatial multiplexing may be used to transmit different streams of data, also referred to as layers, simultaneously on the same time-frequency resource. The data streams may be transmitted to a single UE to increase the data rate or to multiple UEs to increase the overall system capacity, the latter being referred to as multi-user MIMO (MU-MIMO). This is achieved by spatially precoding each data stream (i.e., multiplying the data streams with different weighting and phase shifting) and then transmitting each spatially precoded stream through multiple transmit antennas on the downlink. The spatially precoded data streams arrive at the UE(s) with different spatial signatures, which enables each of the UE(s) to recover the one or more data streams destined for that UE. On the uplink, each UE transmits a spatially precoded data stream, which enables the base station to identify the source of each spatially precoded data stream. 
     The number of data streams or layers corresponds to the rank of the transmission. In general, the rank of the MIMO system  300  is limited by the number of transmit or receive antennas  304  or  308 , whichever is lower. In addition, the channel conditions at the UE, as well as other considerations, such as the available resources at the base station, may also affect the transmission rank. For example, the rank (and therefore, the number of data streams) assigned to a particular UE on the downlink may be determined based on the rank indicator (RI) transmitted from the UE to the base station. The RI may be determined based on the antenna configuration (e.g., the number of transmit and receive antennas) and a measured signal-to-interference-and-noise ratio (SINR) on each of the receive antennas. The RI may indicate, for example, the number of layers that may be supported under the current channel conditions. The base station may use the RI, along with resource information (e.g., the available resources and amount of data to be scheduled for the UE), to assign a transmission rank to the UE. 
     In one example, as shown in  FIG.  3   , a rank-2 spatial multiplexing transmission on a 2×2 MIMO antenna configuration will transmit one data stream from each transmit antenna  304 . Each data stream reaches each receive antenna  308  along a different signal path  310 . The receiver  306  may then reconstruct the data streams using the received signals from each receive antenna  308 . 
     Beamforming is a signal processing technique that may be used at the transmitter  302  or receiver  306  to shape or steer an antenna beam (e.g., a transmit beam or receive beam) along a spatial path between the transmitter  302  and the receiver  306 . Beamforming may be achieved by combining the signals communicated via antennas  304  or  308  (e.g., antenna elements of an antenna array module) such that some of the signals experience constructive interference while others experience destructive interference. To create the desired constructive/destructive interference, the transmitter  302  or receiver  306  may apply amplitude and/or phase offsets to signals transmitted or received from each of the antennas  304  or  308  associated with the transmitter  302  or receiver  306 . 
     In 5G New Radio (NR) systems, particularly for mmWave systems, beamformed signals may be utilized for most downlink channels, including the physical downlink control channel (PDCCH) and physical downlink shared channel (PDSCH). In addition, broadcast information, such as the SSB, CSI-RS, slot format indicator (SFI), and paging information, may be transmitted in a beam-sweeping manner to enable all scheduled entities (UEs) in the coverage area of a transmission and reception point (TRP) (e.g., a gNB) to receive the broadcast information. In addition, for UEs configured with beamforming antenna arrays, beamformed signals may also be utilized for uplink channels, including the physical uplink control channel (PUCCH) and physical uplink shared channel (PUSCH). 
     To facilitate multi-stream communication using SDM, the transmitter  302  and receiver  306  may include a respective TCI state manager  312  and  314  configured to enable configuration of TCI state groups for multi-stream communication between the receiver  306  and the transmitter  302  and between the receiver  306  and at least one additional transmitter (not shown). Here, the receiver  306  may correspond to a UE or other scheduled entity and the transmitter  302  may correspond to a base station or other scheduling entity coordinating communication among multiple TRPs. For example, the TCI state manager  312  of the transmitter  302  may be configured to configure a plurality of TCI state groups for the receiver  304  and to transmit the plurality of TCI state groups to the receiver  304 . For example, the TCI state manager  312  may be configured to transmit an RRC configuration of the plurality of TCI state groups (e.g., an RRC TCI state groups table) to the receiver  304 . The RRC TCI state groups table may include a respective TCI state group identifier for each of the TCI state groups, along with a list of the respective TCI states included within each TCI state group. The TCI state manager  314  of the receiver  304  may then store the plurality of TCI state groups received from the transmitter  302 . 
     In some examples, the TCI state manager  312  of the transmitter  302  may further be configured to transmit an activation message (e.g., a MAC-CE) to the receiver  304  that activates a set of active TCI state groups of the plurality of TCI state groups. The TCI state manager  314  of the receiver  304  may further store the set of active TCI state groups. For a multi-stream PDSCH communication, the TCI state manager  312  of the transmitter  302  may then select one of the active TCI state groups for transmission of the multi-stream PDSCH communication and transmit control information (e.g., DCI) including the selected active TCI state group for the multi-stream PDSCH communication. 
       FIG.  4    is a diagram illustrating an example of beamforming in a multi-TRP environment  400  according to some aspects. The multi-TRP environment  400  includes a plurality of TRPs  404   a  and  404   b , two of which are illustrated for simplicity. The multi-TRP environment  400  may implement spatial division multiplexing (SDM) in which transmissions (streams) from the multiple TRPs  404   a  and  404   b  may be simultaneously directed towards a single UE  402 . In such a multi-TRP environment  400  providing multi-stream transmission, the multiple TRPs  404   a  and  404   b  may be collocated (e.g., at the same geographical location and coupled to the same antenna tower or pole) and/or non-collocated, the latter being illustrated. 
     The TRPs  404   a  and  404   b  may correspond to macro-cells, small cells, pico cells, femto-cells, remote radio heads, relay nodes, or other radio access network (RAN) nodes. Coordination among the TRPs  404   a  and  404   b  for transmission of multiple streams to the UE  402  may be facilitated by a centralized RAN node (e.g., a base station or other centralized RAN node) or via backhaul signaling between the TRPs  404   a  and  404   b . In the example shown in  FIG.  4   , each of the TRPs  404   a  and  404   b  may be remote radio heads (RRHs) of a base station  414  (e.g., gNB). In other examples, each of the TRPs  404   a  and  404   b  may be a separate base station and coordination occurs over an optional backhaul link  416 . The base station  414  may be any of the base stations or scheduling entities illustrated in  FIGS.  1  and/or  3   . The UE  402  may be any of the UEs or scheduled entities illustrated in  FIGS.  1  and/or  3   . 
     The base station  414  may generally be capable of communicating with the UE  402  using one or more transmit beams on one or more of the TRPs  404   a  and  404   b , and the UE  402  may further be capable of communicating with the base station  414  using one or more receive beams. As used herein, the term transmit beam refers to a beam on one of the TRPs  404   a  and  404   b  that may be utilized for downlink or uplink communication with the UE  402 . In addition, the term receive beam refers to a beam on the UE  402  that may be utilized for downlink or uplink communication with the base station  414 . 
     In the example shown in  FIG.  4   , each of the TRPs  404   a  and  404   b  is configured to generate a plurality of transmit beams  406   a - 406   h  and  406   i - 406   p , respectively, each associated with a different spatial direction. In addition, the UE  402  is configured to generate a plurality of receive beams  408   a - 408   g , each associated with a different spatial direction. In some examples, the TRPs  404   a  and  404   b  and UE  402  may each transmit more or less beams distributed in all directions (e.g., 360 degrees) and in three-dimensions. In addition, the transmit beams  406   a - 406   p  may include beams of varying beam width. For example, each of the TRPs  404   a  and  404   b  may transmit certain signals (e.g., SSBs) on wider beams and other signals (e.g., CSI-RSs) on narrower beams. In some examples, the transmit beams  406   a - 406   p  on the TRPs  404   a  and  404   b  and the receive beams  408   a - 408   g  on the UE  402  may be spatially directional mmWave beams (e.g., FR2, FR4-a or FR4-1, FR4, FR5 or other frequency range designation). 
     The base station  414  and UE  402  may select one or more transmit beams  406   a - 406   h  on TRP  404   a , one or more transmit beams  406   i - 406   p  on TRP  404   b , and one or more receive beams  408   a - 408   g  on the UE  402  for communication of uplink and downlink signals therebetween using a beam management procedure. In one example, during initial cell acquisition on each of the TRPs  404   a  and  404   b , the UE  402  may perform a respective P1 beam management procedure to scan the plurality of transmit beams  406   a - 406   h  and  406   i - 406   p  on each of the TRPs  404   a  and  404   b , respectively, on the plurality of receive beams  408   a - 408   g  to select a respective beam pair link (BPL) associated with each of the TRPs  404   a  and  404   b  for a respective physical random access channel (PRACH) procedure for initial access. For example, the UE  402  may select a first BPL including one of the transmit beams  406   a - 406   h  on the TRP  404   a  and a corresponding one of the receive beams  408   a - 408   g  on the UE  402  and a second BPL including one of the transmit beams  406   i - 406   p  on the TRP  404   b  and a corresponding different one of the receive beams  408   a - 408   g  on the UE  402 . 
     For example, periodic SSB beam sweeping may be implemented on each of the TRPs  404   a  and  404   b  at certain intervals (e.g., based on the SSB periodicity). Thus, each TRP  404   a  and  404   b  may be configured to sweep or transmit an SSB on each of a plurality of wider transmit beams  406   a - 406   h  and  406   i - 406   p  during the respective beam sweeping interval. The UE  402  may measure the reference signal received power (RSRP) of each of the SSB transmit beams on each of the receive beams of the UE and, for each of the TRPs  404   a  and  404   b , select the transmit and receive beams based on the measured RSRP. In an example, the selected receive beam may be the receive beam on which the highest RSRP is measured and the selected transmit beam may have the highest RSRP as measured on the selected receive beam. 
     After completing the PRACH procedure, the base station  414  and UE  402  may perform a P2 beam management procedure for beam refinement at the base station  414 . For example, the base station  414  may be configured to sweep or transmit a CSI-RS on each of a plurality of narrower transmit beams  406   a - 406   h  and  406   i - 406   p  on each of the TRPs  404   a  and  404   b . Each of the narrower CSI-RS beams may be a sub-beam of the selected SSB transmit beam (e.g., within the spatial direction of the SSB transmit beam). Transmission of the CSI-RS transmit beams may occur periodically (e.g., as configured via radio resource control (RRC) signaling by the gNB), semi-persistently (e.g., as configured via RRC signaling and activated/deactivated via medium access control-control element (MAC-CE) signaling by the gNB), or aperiodically (e.g., as triggered by the gNB via downlink control information (DCI)). The UE  402  is configured to scan the plurality of CSI-RS transmit beams  406   a - 406   h  and  406   i - 406   p  on one or more receive beams  408   a - 408   g . The UE  402  then performs beam measurements (e.g., RSRP, SINR, etc.) of the received CSI-RSs on the one or more receive beams  408   a - 408   g  to determine the respective beam quality of each of the CSI-RS transmit beams  406   a - 406   h  and  406   i - 406   p  as measured on the one or more receive beams  408   a - 408   g . In some examples, the UE  402  may measure the RSRP of each of the narrower CSI-RS transmit beams  406   a - 406   h  and  406   i - 406   p  from each of the TRPs  404   a  and  404   b  on the corresponding receive beams selected during the P1 procedure. 
     The UE  402  can then generate and transmit a Layer 1 (L1) measurement report, including the respective beam index (e.g., CSI-RS resource indicator (CRI)) and beam measurement (e.g., RSRP or SINR) of one or more of the CSI-RS transmit beams  406   a - 406   h  and  406   i - 406   p  on each of the TRPs  404   a  and  404   b  on one or more of the receive beams  408   a - 408   g  to the base station  414 . The base station  414  may then select one or more CSI-RS transmit beams on each of the TRPs  404   a  and  404   b  on which to communicate downlink and/or uplink control and/or data with the UE  402 . In some examples, the selected CSI-RS transmit beam(s) have the highest RSRP from the L1 measurement report. Transmission of the L1 measurement report may occur periodically (e.g., as configured via RRC signaling by the gNB), semi-persistently (e.g., as configured via RRC signaling and activated/deactivated via MAC-CE signaling by the gNB), or aperiodically (e.g., as triggered by the gNB via DCI). 
     The UE  402  may further select a corresponding receive beam on the UE  402  for each selected serving CSI-RS transmit beam to form a respective beam pair link (BPL) for each selected serving CSI-RS transmit beam. For example, the UE  402  can utilize the beam measurements obtained during the P2 procedure or perform a P3 beam management procedure to obtain new beam measurements for the selected CSI-RS transmit beams to select the corresponding receive beam for each selected transmit beam. In some examples, the selected receive beam to pair with a particular CSI-RS transmit beam may be the receive beam on which the highest RSRP for the particular CSI-RS transmit beam is measured. 
     In addition, when the channel is reciprocal, the transmit and receive beams may be selected using an uplink beam management scheme. In an example, the UE  402  may be configured to sweep or transmit on each of a plurality of receive beams  408   a - 408   g . For example, the UE  402  may transmit an SRS on each beam in the different beam directions. In addition, the base station  414  may be configured to receive the uplink beam reference signals on the plurality of transmit beams  406   a - 406   h  and  406   i - 406   p . The base station  414  then performs beam measurements (e.g., RSRP, SINR, etc.) of the beam reference signals on each of the transmit beams  406   a - 406   h  and  406   i - 406   p  to determine the respective beam quality of each of the receive beams  408   a - 408   g  as measured on each of the transmit beams  406   a - 406   h  and  406   i - 406   p  on each of the TRPs  404   a  and  404   b.    
     The base station  414  may then select one or more transmit beams on each of the TRPs  404   a  and  404   b  on which to communicate downlink and/or uplink control and/or data with the UE  402 . In some examples, the selected transmit beam(s) have the highest RSRP. The UE  402  may then select a corresponding receive beam for each selected serving transmit beam to form a respective beam pair link (BPL) for each selected serving transmit beam, using, for example, a P3 beam management procedure, as described above. 
     In one example, a single transmit beam on each TRP  404   a  and  404   b  (e.g., beam  406   b  and  406   k ) and a single corresponding receive beam (e.g., beam  408   e  and  408   c ) on the UE  402  may form respective single BPLs used for communication between the TRPs  404   a  and  404   b  and the UE  402  for multi-stream communication. For example, a first stream of a PDSCH may be communicated on a first BPL formed of transmit beam  406   b  and receive beam  408   e  and a second stream of a PDSCH may be communicated on a second BPL formed of transmit beam  406   k  and receive beam  408   c.    
     In some examples, after connecting to the base station  414 , the base station  414  may configure the UE  402  to perform SSB and/or CSI-RS beam measurements and provide an L1 measurement report containing beam measurements of SSB and/or CSI-RS transmit beams  406   a - 406   h  and  406   i - 406   p . For example, the base station  414  may configure the UE  402  to perform SSB beam measurements and/or CSI-RS beam measurements for beam management, beam failure detection (BRD), beam failure recovery (BFR), cell reselection, beam tracking (e.g., for a mobile UE  402  and/or base station  414 ), or other beam optimization purpose. 
     In various aspects, upon receiving a beam report (e.g., an L1 measurement report) during a P2 procedure or other beam management procedure from the UE  402 , the base station  414  may configure a plurality of TCI states for the UE  402  and provide the configured TCI states to the UE  402 . For example, the UE  402  and the base station  414  may each include a respective TCI state manager  410  and  412  for managing the configured TCI states for the UE  402 . Each TCI state may include QCL information (e.g., QCL-TypeD information) between a downlink reference signal, such as an SSB or CSI-RS, and a downlink signal or downlink channel (e.g., a PDSCH) to be communicated from the base station  414  to the UE  402 . For example, the QCL-TypeD information may indicate a particular beam on which a PDSCH may be transmitted. 
     For multi-stream communication, the TCI state managers  410  and  412  may further enable TCI state groups to be configured on the base station  414  and UE  402 . Each TCI state group includes a plurality of (e.g., two or more) TCI states, each indicating a respective transmit (downlink) beam on which a corresponding stream of a multi-stream PDSCH communication is transmitted. In some examples, the TCI state manager  412  on the base station  414  may group various transmit beams of the TRPs  404   a  and  404   b  into a plurality of beam groups. Each beam group may include a single transmit beam from each of the TRPs  404   a  and  404   b  for multi-stream communication. The TCI state manager  412  on the base station  414  may then configure a plurality of TCI state groups for the UE  402 , each corresponding to a different respective beam group, and transmit the TCI state groups to the UE  402 . 
     The TCI state groups may be configured, for example, based on a beam report received from the UE  402 . The beam report may correspond to the same beam report transmitted during the P2 procedure or other beam management procedure from which the TCI states are initially configured or may be a subsequent beam report transmitted after configuration of the TCI states for the UE  402 . For example, the base station  414  may configure the UE  402  to perform SSB and/or CSI-RS beam measurements (e.g., as part of a P2 procedure or other subsequent beam management procedure) and provide an L1 measurement report indicating the beam groups. In this example, the UE  402  may obtain a respective beam quality metric (e.g., RSRP) for each transmit beam  406   a - 406   h  and  406   i - 406   p  from each TRP  404   a  and  404   b  on each receive beam  408   a - 408   g  of the UE  402  and transmit the beam report indicating the beam groups based on the respective beam quality metrics. 
     In some examples, the beam report includes a list of two or more recommended beam groups determined by the UE  402  based on the respective beam quality metrics. In other examples, the beam report includes beam quality metric information from which the base station  414  may determine the beam groups. For example, the beam quality metric information may include a respective beam quality metric vector for each of the transmit beams  406   a - 406   p . Each beam quality metric vector is associated with a single transmit beam and includes a respective RSRP measurement of that transmit beam on each receive beam  408   a - 408   g  of the UE  402 . From the beam quality metric vectors, the base station  414  may select the beam groups such that each beam group includes a respective BPL associated with each of the TRPs  404   a  and  404   b  that have minimal mutual interference (e.g., minimum inter-beam interference) therebetween. 
     In some examples, the TCI state manager  412  on the base station  414  may transmit a radio resource control (RRC) configuration of the plurality of TCI state groups (e.g., an RRC TCI state groups table) to the UE  402 . The RRC TCI state groups table may include a respective TCI state group identifier and a list of the TCI states included within the respective TCI state group for each of the TCI state groups. The TCI state manager  410  on the UE  402  may then store the RRC TCI state groups table for use in receiving a subsequent multi-stream communication. In some examples, the TCI state manager  412  on the base station  414  may further activate/deactivate one or more of the plurality of TCI state groups via a MAC-CE. For example, the TCI state manager  410  may transmit an activation message (e.g., a MAC-CE) to the UE  402  that activates a set of active TCI state groups of the plurality of TCI state groups. In some examples, the set of active TCI state groups includes up to eight active TCI state groups that may be selected from for PDSCH transmissions. The TCI state manager  410  on the UE  402  may further store the set of active TCI state groups. For a multi-stream PDSCH communication, the TCI state manager  412  on the base station  414  may then select one of the active TCI state groups for transmission of the multi-stream PDSCH communication and include the selected active TCI state group in the control information (e.g., DCI) scheduling the multi-stream PDSCH communication. 
       FIG.  5    is a diagram illustrating an example of multi-stream communication between a UE  502  and a radio access network (RAN) entity  504  according to some aspects. The RAN entity  504  may be any of the base stations (e.g., gNBs) or scheduling entities illustrated in  FIGS.  1   , and/or  4 , and the UE  502  may be any of the UEs or scheduled entities illustrated in  FIGS.  1   , and/or  4 . The RAN entity  504  may be configured to coordinate communication amongst a plurality of TRPs  506 ,  508 , and  510 . The TRPs  506 ,  508 , and  510  may be collocated or non-collocated. In the example shown in  FIG.  5   , TRPs  506  and  508  are collocated, whereas TRP  510  is non-collocated with either of the other TRPs  506  and  508 . 
     The UE  502  may include a single antenna panel  512  or multiple antenna panels, the latter being illustrated in  FIG.  5   . For example, the antenna panels  512  may be located at various positions on the UE  502  to enable each antenna panel  512  to cover a respective portion of a sphere surrounding the UE  502 . Each antenna panel  512  may support a plurality of beams (e.g., receive beams). For mmWave (e.g., FR2 or higher) communication, multiple concurrent beams may be supported by the same antenna panel  512  using, for example, a Butler matrix. For example, the UE  502  may include P antenna panels, each supporting up to B beams. A number of active antenna panels K, where K≤P, can be used at the same time to receive multiple streams S, where S≤K*B. Here, the K*B beams may be referred to as a beam collection (e.g., a collection of beams). The UE  502  may process each beam in the beam collection independently, up to the log likelihood ratio (LLR) level. 
     The RAN entity  504 , acting as a multi-TRP (m-TRP), can be configured to provide S independent streams on S separate beams. In the example shown in  FIG.  5   , the RAN entity  504  may provide a first stream on a first transmit beam  514   a  from TRP  506 , a second stream on a second transmit beam  514   b  from TRP  508 , and a third stream on a third transmit beam  514   c  from TRP  510 . Each transmit beam  514   a ,  514   b , and  514   c  may be directed (e.g., via a line-of-sight path or reflection off of one or more objects  518 ) towards the UE  502  and received via a respective receive beam  516   a ,  516   b , and  516   c  on the UE  502 . Thus, each transmit beam  514   a - 514   c  and corresponding receive beam  516   a - 516   c  form a respective BPL between the RAN entity  504  and the UE  502 . The receive beams  516   a - 516   c  may correspond to the same antenna panel  512 , as shown in  FIG.  5   , or different antenna panels. Using the same antenna panel may reduce power consumption at the UE, as only a single antenna panel is turned on. 
     In various aspects, the RAN entity  504  may select the transmit beams  514   a - 514   c  (e.g., downlink serving beams) for SDM of multiple streams of a PDSCH based on TCI state groups configured for the UE  502 . For example, the UE  502  and RAN entity  504  may each include a respective TCI state manager  520  and  522  configured to manage TCI states and TCI state groups for the UE  502 . The TCI state manager  522  on the RAN entity  504  may configure a plurality of TCI states for the UE  502  based on, for example, a beam report (e.g., an L1 measurement report) and provide the configured TCI states to the UE  502 . The TCI state manager  522  on the RAN entity  504  may further configure a plurality of TCI state groups for the UE  502 . Each TCI state group includes a plurality of (e.g., two or more) TCI states, each indicating a respective transmit (downlink) beam on which a corresponding stream of a multi-stream PDSCH communication may be transmitted. 
     In some examples, the TCI state manager  522  on the RAN entity  504  may group various transmit beams of the TRPs  506 ,  508 , and  510  into a plurality of beam groups. Each beam group may include a single transmit beam from each of two or more of the TRPs  506 ,  508 , and  510  for multi-stream communication. The TCI state manager  522  on the RAN entity  504  may then configure a plurality of TCI state groups for the UE  502 , each corresponding to a different respective beam group, and transmit the TCI state groups to the UE  502 . 
     The TCI state groups may be configured, for example, based on a beam report received from the UE  502 . The beam report may correspond to the same beam report utilized for the initial configuration of the TCI states or may be a subsequent beam report transmitted after configuration of the TCI states for the UE  502 . For example, the beam report may be an L1-RSRP report or L1-SINR report (e.g., SSB resource indicator (SRI) or CSI-RS resource indicator (CRI) based beam report). The beam report may include information indicating the plurality of beam groups (e.g., two or more beam groups) that may be selected from for a PDSCH multi-stream communication. Each beam group may include a single transmit beam from each of two or more of the TRPs  506 ,  508 , and  510  that collectively produce a minimum mutual interference (e.g., minimum inter-beam interference) therebetween. 
     For example, the RAN entity  504  may configure the UE  502  (e.g., via RRC signaling) to obtain multiple parallel or serial beam quality metrics on each of the receive beams (e.g., of each of the panels  512 ) for each of the transmit beams to generate a respective beam quality metric vector for each of the transmit beams. The UE  502  may then generate and transmit a beam report indicating the beam groups based on the beam quality metric vectors. In some examples, the beam report includes a list of two or more recommended beam groups identified by the UE  502  based on the respective beam quality metric vectors. In other examples, the beam report includes the respective beam quality metric vector for each of the transmit beams. The RAN entity  504  may then be configured to group the transmit beams into the beam groups based on the beam report, such that each beam group includes one transmit beam from each of two or more of the TRPs  506 ,  508 , and  510  for multi-stream communication between the TRPs  506 ,  508 , and  510  and the UE  502 . In some examples, for each beam group, the selected transmit beams in that beam group provide a minimal mutual interference (e.g., minimum inter-beam interference) therebetween. 
     In some examples, the TCI state manager  522  on the RAN entity  504  may transmit a radio resource control (RRC) configuration of the plurality of TCI state groups (e.g., an RRC TCI state groups table) to the UE  502 . The RRC TCI state groups table may include a respective TCI state group identifier and a list of the TCI states included within the respective TCI state group for each of the TCI state groups. The TCI state manager  520  on the UE  502  may then store the RRC TCI state groups table for use in receiving a subsequent multi-stream communication. In some examples, the TCI state manager  522  on the RAN entity  504  may further activate/deactivate one or more of the plurality of TCI state groups via a MAC-CE. For example, the TCI state manager  522  may transmit an activation message (e.g., a MAC-CE) to the UE  502  that activates a set of active TCI state groups of the plurality of TCI state groups. In some examples, the set of active TCI state groups includes up to eight active TCI state groups that may be selected from for PDSCH transmissions. The TCI state manager  520  on the UE  502  may further store the set of active TCI state groups. For a multi-stream PDSCH communication, the TCI state manager  522  on the RAN entity  504  may then select one of the active TCI state groups for transmission of the multi-stream PDSCH communication and include the selected active TCI state group in the control information (e.g., DCI) scheduling the multi-stream PDSCH communication. For example, the TCI state manager  522  on the RAN entity  504  may select the TCI state group corresponding to a beam group including transmit beams  514   a  and  514   c  for the multi-stream PDSCH communication. 
       FIG.  6    is a diagram illustrating an example of a TCI state group configuration between a UE  602  and a RAN entity  604  for multi-stream communication according to some aspects. The RAN entity  604  may be any of the base stations (e.g., gNBs) or scheduling entities illustrated in  FIGS.  1 ,  4   , and/or  5 , and the UE  602  may be any of the UEs or scheduled entities illustrated in  FIGS.  1 ,  4   , and/or  5 . 
     The RAN entity  604  may be configured to coordinate communication amongst a plurality of TRPs  606 ,  608 , and  610  for SDM of multiple streams to the UE  602 . The TRPs  606 ,  608 , and  610 , may be collocated or non-collocated. In the example shown in  FIG.  6   , TRPs  606  and  608  are collocated, while TRP  610  is non-collocated with either TRP  606  or TRP  608 . Each of the TRPs  606 ,  608 , and  610  may support a plurality of transmit beams  614   a ,  614   b , and  614   c , one of which on each TRP  606 ,  608 , and  610  is shown for convenience. Each transmit beam  614   a ,  614   b , and  614   c  may be utilized to transmit a respective stream to the UE  602  (e.g., via respective line-of-sight paths or reflection from one or more objects  618 ). 
     The UE  602  may include a plurality of antenna panels  612   a  and  612   b , two of which are shown for convenience. The antenna panels  612   a  and  612   b  may support a plurality of beams (e.g., receive beams)  616   a - 616   h . For example, antenna panel  612   a  may support receive beams  616   a - 616   d  and antenna panel  612   b  may support receive beams  616   e - 616   h . The set of all receive beams  616   a - 616   h  on active panels (e.g., panels  612   a  and  612   b ) on the UE  602  may be referred to as a collection of beams (e.g., a beam collection). In various aspects of the disclosure, all receive beams in the beam collection may be operated simultaneously by the UE  602 . 
     The UE  602  and the RAN entity  604  may each include a respective TCI state manager  620  and  622  configured to facilitate TCI state groups. The TCI state manager  622  on the RAN entity  604  may configure a plurality of TCI states for the UE  602  based on, for example, a beam report (e.g., an L1 measurement report) and provide the configured TCI states to the UE  602 . The TCI state manager  622  on the RAN entity  604  may further configure a plurality of TCI state groups for the UE  602 . Each TCI state group includes a plurality of (e.g., two or more) TCI states, each indicating a respective transmit (downlink) beam on which a corresponding stream of a multi-stream PDSCH communication may be transmitted. 
     In some examples, the TCI state manager  622  on the RAN entity  604  may utilize the beam report sent from the UE  602  as part of a P2 beam refinement procedure or other beam management procedure to configure the TCI state groups. For example, during the beam management procedure, the RAN entity  604  may generate and transmit a plurality of transmit beams  614   a ,  614   b , and  614   c  (e.g., SSB beams or CSI-RS beams) from the TRPs  606 ,  608 , and  610  within a frequency band (e.g., FR2, FR4-a, FR4-1, FR4, FR5 or other mmWave or higher frequency band). For example, the RAN entity  604  may generate and transmit a respective beam reference signal (e.g., SSB or CSI-RS) on each of the transmit beams  614   a ,  614   b , and  614   c . The transmit beams  614   a ,  614   b , and  614   c  include at least one transmit beam from each TRP  606 ,  608 , and  610 , as shown in  FIG.  6   . In some examples, the transmit beams  614   a ,  614   b , and  614   c  may include active beams (e.g., transmit beams activated, for example, via a MAC-CE) on the TRPs  606 ,  608 , and  610 . In some examples, the transmit beams  614   a ,  614   b , and  614   c  include sub-beams (e.g., CSI-RS beams) of active SSB beams on each of the TRPs  606 ,  608 , and  610  or SSB beams on each of the TRPs transmitted in a beam sweep across the TRPs  606 ,  608 , and  610 . In some examples, the transmit beams  614   a ,  614   b , and  614   c  include a plurality of SSB beams and/or CSI-RS beams that may not yet be activated for the UE  602 . 
     For each transmit beam  614   a ,  614   b , and  614   c  transmitted during the beam management procedure, the UE  602  may obtain a beam quality metric on each of the receive beams  616   a - 616   h  in the beam collection in parallel (e.g., using a Butler matrix) or serially during a measurement period to generate a beam quality metric vector for each transmit beam  614   a ,  614   b , and  614   c . Examples of beam quality metrics include, but are not limited to, RSRP or SINR. For example, the UE  602  may measure the RSRP of a transmit beam (e.g., transmit beam  614   a ) on each of the receive beams  616   a - 616   h  and generate an RSRP vector of the measured RSRP values of the transmit beam  614   a  on each of the receive beams  616   a - 616   h . The UE  602  may then repeat the parallel or serial RSRP measurements of each of the other transmit beams  614   b  and  614   c  to generate respective RSRP vectors for transmit beams  614   b  and  614   c . The UE  602  may obtain the RSRP vectors by measuring the RSRP of the beam reference signal (e.g., SSB or CSI-RS) transmitted on the transmit beams  614   a ,  614   b , and  614   c.    
     The UE  602  may then generate a beam report indicating a plurality of beam groups based on the beam quality metric vectors. In some examples, the beam report includes a list of two or more recommended beam groups identified by the UE  602  based on the respective beam quality metric vectors. In other examples, the beam report includes the respective beam quality metric vector for each of the transmit beams  614   a ,  614   b , and  614   c . The RAN entity  604  may then be configured to group the transmit beams into the beam groups based on the beam report, such that each beam group includes one transmit beam from each of two or more of the TRPs  606 ,  608 , and  610  for multi-stream communication between the TRPs  606 ,  608 , and  610  and the UE  602 . In some examples, for each beam group, the selected transmit beams in that beam group provide a minimal mutual interference (e.g., minimum inter-beam interference) therebetween. For example, the transmit beams selected for each beam group may have the strongest RSRP that provide the minimum mutual interference therebetween. 
     In some examples, the TCI state manager  622  on the RAN entity  604  may transmit a radio resource control (RRC) configuration of the plurality of TCI state groups (e.g., an RRC TCI state groups table) to the UE  602 . The RRC TCI state groups table may include a respective TCI state group identifier and a list of the TCI states included within the respective TCI state group for each of the TCI state groups. The TCI state manager  620  on the UE  602  may then store the RRC TCI state groups table for use in receiving a subsequent multi-stream communication. In some examples, the TCI state manager  622  on the RAN entity  604  may further transmit an activation message (e.g., a MAC-CE) to the UE  602  that activates a set of active TCI state groups of the plurality of TCI state groups. In some examples, the set of active TCI state groups includes up to eight active TCI state groups that may be selected from for PDSCH transmissions. The TCI state manager  620  on the UE  602  may further store the set of active TCI state groups. For a multi-stream PDSCH communication, the TCI state manager  622  on the RAN entity  604  may then select one of the active TCI state groups for transmission of the multi-stream PDSCH communication and include the selected active TCI state group in the control information (e.g., DCI) scheduling the multi-stream PDSCH communication. For example, the TCI state manager  622  on the RAN entity  604  may select the TCI state group corresponding to the beam group including transmit beams  614   a  and  614   c  for the multi-stream PDSCH communication. 
       FIG.  7    is a diagram illustrating an example of beam quality metric vectors  700   a ,  700   b , and  700   c  obtained during the beam management procedure of  FIG.  6    according to some aspects. Each beam quality metric vector  700   a ,  700   b , and  700   c  may correspond, for example, to an RSRP vector. A first RSRP vector  700   a  includes the RSRP of transmit beam  614   a  (Tx beam  1 ) as measured in parallel or serially on each of the four receive beams  616   a - 616   d  on antenna panel  612   a  and as measured in parallel or serially on each of the four receive beams  616   e - 616   h  on antenna panel  612   b . A second RSRP vector  700   b  includes the RSRP of transmit beam  614   b  (Tx beam  2 ) as measured in parallel or serially on each of the four receive beams  616   a - 616   d  on antenna panel  612   a  and as measured in parallel or serially on each of the four receive beams  616   e - 616   h  on antenna panel  612   b . A third RSRP vector  700   c  includes the RSRP of transmit beam  614   c  (Tx beam  3 ) as measured in parallel or serially on each of the four receive beams  616   a - 616   d  on antenna panel  612   a  and as measured in parallel or serially on each of the four receive beams  616   e - 616   h  on antenna panel  612   b.    
     As can be seen in the example of  FIG.  7   , candidate receive beams to form a BPL with Tx beam  1  (e.g., receive beams having the strongest RSRP of Tx beam  1 ) may include the first receive beam (e.g., receive beam  616   a ) on antenna panel  612   a , the first receive beam (e.g., receive beam  616   e ) on antenna panel  612   b , and the second receive beam (e.g., receive beam  616   b ) on antenna panel  612   a . In addition, candidate receive beams to form a BPL with Tx beam  2  (e.g., receive beams having the strongest RSRP of Tx beam  2 ) may include the first receive beam (e.g., receive beam  616   a ) on antenna panel  612   a , the first receive beam (e.g., receive beam  616   e ) on antenna panel  612   b , and the second receive beam (e.g., receive beam  616   f ) on antenna panel  612   b . Furthermore, candidate receive beams to form a BPL with Tx beam  3  (e.g., receive beams on which the strongest RSRP of Tx beam  3  was measured) may include the second receive beam (e.g., receive beam  616   f ) on antenna panel  612   b  and the third receive beam (e.g., receive beam  616   g ) on antenna panel  612   b.    
     To minimize the mutual interference experienced by the UE  602  between BPLs, different receive beams on the same or different panels may be selected to form BPLs with respective ones of the transmit beams. For example, the RAN entity  604  (or UE  602 ) may select the first receive beam (e.g., receive beam  616   e ) on the second antenna panel  612   b  to form a BPL with Tx beam  2  (e.g., transmit beam  614   b ) and the second receive beam (e.g., receive beam  616   f ) on the second antenna panel  612   b  to form a BPL with Tx beam  3  (e.g., transmit beam  614   c ). In this example, transmit beams  614   b  and  614   c  may form a beam group. Thus, the RAN entity  604  may configure a TCI state group corresponding to the beam group including transmit beams  614   b  and  614   c.    
     In addition, the RAN entity  604  (or the UE  602 ) may also select the first receive beam (e.g., receive beam  616   a ) on the first antenna panel  612   a  to form a BPL with Tx beam  1  (e.g., transmit beam  614   a ) and the second receive beam (e.g., receive beam  616   f ) on the second antenna panel  612   b  to form a BPL with Tx beam  3  (e.g., transmit beam  614   c ). In this example, transmit beams  614   a  and  614   c  may form a beam group. Thus, the RAN entity  604  may also configure a TCI state group corresponding to the beam group including transmit beams  614   a  and  614   c . The number of selected BPLs (e.g., the number of transmit beams within each beam group) may correspond to the number of different data streams configured for communication between the RAN entity  604  and the UE  602 . 
       FIG.  8    is a signaling diagram illustrating an exemplary TCI state management procedure between a UE  802  and an m-TRP RAN entity  804  according to some aspects. The m-TRP RAN entity  804  may be any of the base stations (e.g., gNBs) or scheduling entities illustrated in  FIGS.  1   , and/or  4 - 6 , and the UE  802  may be any of the UEs or scheduled entities illustrated in  FIGS.  1   , and/or  4 - 6 . The m-TRP RAN entity  804  may be configured to coordinate communication amongst a plurality of TRPs (m TRPs), which may be collocated or non-collocated, for the multi-stream communication. 
     At  806 , the m-TRP RAN entity  804  may perform an initial cell search to identify a respective beam pair link (BPL) associated with each of the TRPs. For example, the UE  802  may perform a respective P1 beam management procedure to scan a plurality of transmit beams of each of the TRPs on a plurality of receive beams of the UE  802  to select a respective beam pair link (BPL) associated with each of the TRPs. At  808 , the UE  802  may then perform a respective PRACH procedure over the selected BPLs on each of the TRPs to connect to the m-TRP RAN entity  804 . 
     At  810 , the m-TRP RAN entity  804  may transmit a plurality of transmit beams in a mmWave frequency band (e.g., FR2 or higher frequency band), each carrying a respective beam reference signal (e.g., SSB or CSI-RS) to the UE  802 . The m-TRP RAN entity  804  may transmit the plurality of transmit beams during a P2 beam refinement procedure or other beam management procedure in which a beam report (e.g., an L1-RSRP report) is generated. In some examples, each of the m-TRPs transmits at least one of the plurality of transmit beams. In other examples, a subset of the m-TRPs transmits the transmit beams towards the UE  802 . For example, the subset of the m-TRPs may include active TRPs activated for multi-cell (multi-TRP) communication with the UE  802 . 
     At  812 , the UE  802  may obtain a beam quality metric on each of the received transmit beams. For example, the UE  802  may measure the beam quality metric (e.g., RSRO) of each of the received transmit beams on one or more receive beams. In some examples, the UE  802  may measure the RSRP of each of the received transmit beams from each of the TRPs on the corresponding receive beams selected during the initial access procedure. At  814 , the UE may generate and transmit a beam report (e.g., L1 measurement report) to the m-TRP RAN entity  804 . The beam report may include, for example, the respective beam index (e.g., SRI or CRI) and beam measurement (e.g., RSRP) of one or more of the received transmit beams for each of the TRPs. 
     At  816 , the m-TRP RAN entity  804  may configure a plurality of TCI states for the UE  802  and transmit an RRC configuration of the plurality of TCI states to the UE  802 . For example, based on the beam report, the m-TRP RAN entity  804  may select a plurality of transmit beams across the TRPs for communication with the UE and configure a respective TCI state for each of the selected transmit beams. The selected transmit beams may, for example, have the highest RSRP or have a spatial direction within, for example, a pre-configured three-dimensional area around the transmit beam(s) having the highest RSRP. 
       FIG.  9    is a signaling diagram illustrating another exemplary TCI state management procedure between a UE  902  and an m-TRP RAN entity  904  for multi-stream communication according to some aspects. The m-TRP RAN entity  904  may be any of the base stations (e.g., gNBs) or scheduling entities illustrated in  FIGS.  1 ,  4 - 6   , and/or  8  and the UE  902  may be any of the UEs or scheduled entities illustrated in  FIGS.  1 ,  4 - 6   , and/or  8 . The m-TRP RAN entity  904  may be configured to coordinate communication amongst a plurality of TRPs (m TRPs), which may be collocated or non-collocated, for the multi-stream communication 
     At  906 , the m-TRP RAN entity  904  may initiate a beam management procedure by transmitting a plurality of transmit beams in a mmWave frequency band (e.g., FR2 or higher frequency band), each carrying a respective beam reference signal (e.g., SSB or CSI-RS) to the UE  902 . The beam management procedure may be the beam management procedure described at  810  of  FIG.  8    or a second (subsequent) beam management procedure. In some examples, the plurality of transmit beams includes the transmit beams corresponding to the RRC configured TCI states for the UE  902 . In other examples, the plurality of transmit beams includes a subset of the transmit beams corresponding to the RRC configured TCI states for the UE  902 . For example, the subset of transmit beams may include active transmit beams activated (e.g., via MAC-CE) for communication with the UE  902 . In some examples, each of the m-TRPs transmits at least one of the plurality of transmit beams. In other examples, a subset of the m-TRPs transmits the transmit beams towards the UE  902 . For example, the subset of the m-TRPs may include active TRPs activated for multi-cell (multi-TRP) communication with the UE  902 . 
     At  908 , the UE obtains a respective beam quality metric vector for each of the transmit beams. For example, for each transmit beam, the UE  902  may measure a respective beam quality metric (e.g., RSRP) on each of a plurality of receive beams during a measurement period. The receive beams may include all receive beams on all antenna panels of the UE  902  or a subset of the receive beams or a subset of the antenna panels. The UE  902  may then place the beam quality metric values measured on each of the receive beams for each of the transmit beams in a respective beam quality metric vector for each of the transmit beams. 
     In some examples, for each transmit beam, the UE  902  may measure the respective beam quality metric on each of the plurality of receive beams in parallel (e.g., at the same time). For example, the UE  902  may utilize a Butler matrix to perform the parallel measurements. Here, the parallel measurements on each of the receive beams are conducted on a single transmit beam, such that the parallel measurements are performed substantially simultaneously. In this example, the measurement period may correspond to a duration of time during which the parallel measurements are performed. In some examples, for each transmit beam, the UE  902  may measure the respective beam quality metric on each of the plurality of receive beams serially (e.g., on one receive beam at a time). Here, the serial measurements on each of the receive beams are conducted on respective repetitions of the transmit beam, such that one measurement is obtained on each receive beam at a time using one of the repetitions of the transmit beam. In this example, the measurement period may correspond to a duration of time during which all of the repetitions of the transmit beam are transmitted and serially measurements are obtained of the repetitions on respective receive beams of the UE. In some examples, for each transmit beam, the UE  902  may measure the respective beam quality metric on each of the plurality of receive beams in parallel for each of a plurality of repetitions of the transmit beam. In this example, the UE  902  may utilize the repetitions of the transmit beam to double the vector length. Here, the measurement period may correspond to a duration of time during which all repetitions of the transmit beam are transmitted and substantially simultaneous measurements are obtained on each of the receive beams for each of the repetitions. 
     At  910 , the UE  902  may then generate and transmit a beam report indicating a plurality of beam groups based on the beam quality metric vectors. In some examples, the beam report includes the plurality of beam groups (e.g., a list of two or more recommended beam groups) identified by the UE  902  based on the respective beam quality metric vectors. In other examples, the beam report includes the respective beam quality metric vector for each of the received transmit beams. 
     At  912 , the m-TRP RAN entity  904  may group the plurality of transmit beams into the plurality of beam groups based on the beam report. In examples in which the beam report includes plurality of beam groups, the m-TRP RAN entity  904  may group the plurality of transmit beams into the plurality of beam groups indicated in the beam report. In examples in which the beam report includes beam quality metric vectors, the m-TRP RAN entity  904  may group the plurality of transmit beams into the plurality of beam groups based on the beam quality metric vectors. For example, the transmit beams selected for a particular beam group may have the strongest RSRP that provides the minimum mutual interference (e.g., minimum inter-beam interference) therebetween based on selected BPLs. 
     At  914 , m-TRP RAN entity  904  may configure a plurality of TCI state groups for the UE  902  and transmit an RRC configuration of the plurality of TCI state groups to the UE  902 . Each TCI state group corresponds to a respective one of the plurality of beam groups and includes a plurality of (e.g., two or more) TCI states, each corresponding to a respective one of the transmit beams in the respective beam group. In some examples, the RRC configuration of the plurality of TCI state groups includes an RRC TCI state groups table. The RRC TCI state groups table may include a respective TCI state group identifier and a list of the TCI states included within the respective TCI state group for each of the TCI state groups. 
     At  916 , the m-TRP RAN entity  904  may select a set of active TCI state groups from the plurality of TCI state groups and transmit an activation message (e.g., a MAC-CE) to the UE  902  that activates the set of active TCI state groups. In some examples, the set of active TCI state groups includes up to eight active TCI state groups that may be selected from for multi-stream PDSCH transmissions. 
     At  918 , the m-TRP RAN entity  904  may select one of the active TCI state groups for transmission of a multi-stream PDSCH communication and transmit control information (e.g., DCI) including the selected active TCI state group. The control information may further include scheduling information scheduling the multi-stream PDSCH communication. For example, the scheduling information may include time-frequency resources on which the multi-stream PDSCH communication is to be transmitted, a selected MCS, a selected rank, and other suitable scheduling information. In some examples, each BPL (e.g., as indicated by the TCI state group) on which the PDSH communication is transmitted may have a rank of two using horizontal/vertical polarization. In some examples, the DCI may include a plurality of bits indicating the selected TCI state group for the multi-stream PDSCH communication. For example, the DCI may include three bits indicating the selected TCI state group. 
     At  920 , the m-TRP RAN entity  904  may SDM at least two streams of a PDSCH to the UE  902  using the selected active TCI state group. For example, the m-TRP RAN entity  904  may SDM each of the at least two streams from a different respective TRP on a respective transmit beam corresponding to that TRP. 
       FIGS.  10 A and  10 B  are diagrams illustrating examples of beam reports  1002   a  and  1002   b  including an indication of beam groups according to some aspects. The beam reports  1002   a  and  1002   b  may each be, for example, an L1 measurement report. In the example shown in  FIG.  10 A , the L1 measurement report  1002   a  includes a respective beam quality metric (BQM) vector  1004  for each of a plurality of transmit beams  1006  identified by a respective CSI-RS resource indicator (CRI). For example, the L1 measurement report  1002   a  may include BQM Vectors 1-4, each associated with a respective CRI 1-4. Each BQM vector  1004  may include, for example, an RSRP vector, such as the RSRP vectors  700   a - 700   c  shown in  FIG.  7   . 
     In the example shown in  FIG.  10 B , the L1 measurement report  1002   b  includes a plurality of beam groups  1008 , each including a plurality of transmit beams  1006 . For example, a first beam group  1008   a  (beam group  1 ) may include, for example, transmit beams CR 1 , CR 2 , and CR 3 . In addition, a second beam group  1008   b  (beam group  2 ) may include, for example, transmit beams CR 2  and CR 4 . In some examples, the L1 measurement report  1002   b  may include the plurality of beam groups  1008 , together with other beam quality metric information (not shown) for one or more transmit beams. For example, the L1 measurement report  1002   b  may further include the CRI and measured RSRP for one or more transmit beams having the highest RSRP. As another example, the L1 measurement report  1002   b  may further include the CRI and associated beam quality metric vector for each of the plurality of transmit beams (as shown in  FIG.  10 A ). 
       FIGS.  11 A and  11 B  are diagram illustrating radio resource control (RRC) TCI state tables  1100   a  and  1100   b  according to some aspects. The RRC TCI state table  1100   a  shown in  FIG.  11 A  illustrates an example of a TCI state  1102  configured for a UE. Thus, the RRC TCI state table  1100   a  may correspond to a TCI state table including a plurality of TCI states configured for the UE. The TCI state  1102  includes a TCI state ID  1104  identifying the TCI state, along with a plurality of QCL information  1106  (e.g., QCL-TypeA, QCL-TypeB, etc.). For example, QCL-TypeA may indicate a downlink reference signal (e.g., SSB or CSI-RS) from which the channel properties of a downlink channel or signal may be inferred. QCL-TypeB and QCL-TypeC may also indicate downlink reference signals from which specific channel properties (e.g., Doppler shift and/or Doppler spread for QCL-TypeB and average delay and/or delay spread for QCL-TypeC) may be inferred. QCL-TypeD may indicate a spatial RX parameter (e.g., spatial property of the beam on which a downlink channel or signal is transmitted). The spatial property of the beam may be inferred from the beam utilized for transmission of a downlink reference signal and may indicate, for example, at least one of a beam direction or a beam width. 
     The RRC state table  1100   b  shown in  FIG.  11 B  illustrates an example of a TCI state group  1108  configured for a UE. Thus, the RRC TCI state table  1100   b  may correspond to a TCI state group table including a plurality of TCI state groups configured for the UE. The TCI state group  1108  includes a TCI state group ID  1110  identifying the TCI state group, along with a plurality of TCI states  1112  included within the TCI state group  1108 . Each TCI state  1112  may correspond, for example, to one of the TCI states  1102  included in the TCI state table  1100   a.    
       FIG.  12    is a conceptual diagram illustrating an example of a hardware implementation for an exemplary UE  1200  employing a processing system  1214 . For example, the UE  1200  may be any of the UEs or scheduled entities illustrated in any one or more of  FIGS.  1 ,  2 ,  5 - 7   , and/or  9 . 
     The UE  1200  may be implemented with a processing system  1214  that includes one or more processors  1204 . Examples of processors  1204  include microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure. In various examples, the UE  1200  may be configured to perform any one or more of the functions described herein. That is, the processor  1204 , as utilized in a UE  1200 , may be used to implement any one or more of the processes described below in connection with  FIG.  12   . 
     The processor  1204  may in some instances be implemented via a baseband or modem chip and in other implementations, the processor  1204  may itself comprise a number of devices distinct and different from a baseband or modem chip (e.g., in such scenarios as may work in concert to achieve aspects discussed herein). And as mentioned above, various hardware arrangements and components outside of a baseband modem processor can be used in implementations, including RF-chains, power amplifiers, modulators, buffers, interleavers, adders/summers, etc. 
     In this example, the processing system  1214  may be implemented with a bus architecture, represented generally by the bus  1202 . The bus  1202  may include any number of interconnecting buses and bridges depending on the specific application of the processing system  1214  and the overall design constraints. The bus  1202  communicatively couples together various circuits including one or more processors (represented generally by the processor  1204 ), a memory  1205 , and computer-readable media (represented generally by the computer-readable medium  1206 ). The bus  1202  may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further. 
     A bus interface  1208  provides an interface between the bus  1202  and a transceiver  1210 . The transceiver  1210  provides a means for communicating with various other apparatus over a transmission medium (e.g., air interface). In some examples, the transceiver  1210  may include a phase-shifter  1216  for digital and/or analog beamforming via one or more antenna array(s)  1230 . Each antenna array  1230  may correspond, for example, to an antenna panel. Multiple antenna panels may be positioned in various locations on the UE  1200  to provide full spatial coverage and meet maximum permissible exposure requirements. A user interface  1212  (e.g., keypad, display, speaker, microphone, joystick) may also be provided. 
     The processor  1204  is responsible for managing the bus  1202  and general processing, including the execution of software stored on the computer-readable medium  1206 . The software, when executed by the processor  1204 , causes the processing system  1214  to perform the various functions described below for any particular apparatus. The computer-readable medium  1206  and the memory  1205  may also be used for storing data that is manipulated by the processor  1204  when executing software. 
     One or more processors  1204  in the processing system may execute software. Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. The software may reside on a computer-readable medium  1206 . 
     The computer-readable medium  1206  may be a non-transitory computer-readable medium. A non-transitory computer-readable medium includes, by way of example, a magnetic storage device (e.g., hard disk, floppy disk, magnetic strip), an optical disk (e.g., a compact disc (CD) or a digital versatile disc (DVD)), a smart card, a flash memory device (e.g., a card, a stick, or a key drive), a random access memory (RAM), a read only memory (ROM), a programmable ROM (PROM), an erasable PROM (EPROM), an electrically erasable PROM (EEPROM), a register, a removable disk, and any other suitable medium for storing software and/or instructions that may be accessed and read by a computer. The computer-readable medium  1206  may reside in the processing system  1214 , external to the processing system  1214 , or distributed across multiple entities including the processing system  1214 . The computer-readable medium  1206  may be embodied in a computer program product. In some examples, the computer-readable medium  1206  may be part of the memory  1205 . By way of example, a computer program product may include a computer-readable medium in packaging materials. Those skilled in the art will recognize how best to implement the described functionality presented throughout this disclosure depending on the particular application and the overall design constraints imposed on the overall system. 
     In some aspects of the disclosure, the processor  1204  may include circuitry configured for various functions. For example, the processor  1204  may include communication and processing circuitry  1242 , configured to communicate with a RAN entity, such as a m-TRP base station or other scheduling entity. In some examples, the communication and processing circuitry  1242  may include one or more hardware components that provide the physical structure that performs processes related to wireless communication (e.g., signal reception and/or signal transmission) and signal processing (e.g., processing a received signal and/or processing a signal for transmission). 
     In some examples, the communication and processing circuitry  1242  may be configured to receive and process downlink beamformed signals at a mmWave frequency (e.g., FR2, FR4-a, FR4-1, FR4, FR5, etc.) via the transceiver  1210  and the antenna arrays  1230  (e.g., using the phase-shifter  1216 ). In addition, the communication and processing circuitry  1242  may be configured to generate and transmit uplink beamformed signals at a mmWave frequency via the transceiver  1210  and antenna arrays  1230  (e.g., using the phase-shifter  1216 ). For example, the communication and processing circuitry  1242  may be configured for multi-stream communication with the m-TRP RAN entity via spatial division multiplexing (SDM) of the multiple streams on corresponding multiple beam pair links (BPLs) between the UE  1200  and respective TRPs. 
     The communication and processing circuitry  1242  may further be configured to receive a plurality of transmit beams from a plurality of TRPs of a m-TRP RAN entity on a plurality of receive beams via the antenna arrays  1230  and transceiver  1210 . Each of the transmit beams may carry a respective beam reference signal (e.g., an SSB or CSI-RS). The communication and processing circuitry  1242  may further be configured to transmit a beam report (e.g., an L1 measurement report) to the m-TRP RAN entity. The communication and processing circuitry  1242  may further be configured to execute communication and processing software  1252  stored in the computer-readable medium  1206  to implement one or more of the functions described herein. 
     The processor  1204  may further include beam manager circuitry  1244 , configured to perform beam management for SDM multi-stream communication. The beam manager circuitry  1244  may be configured to perform beam management for SDM multi-stream communication during a beam refinement procedure (e.g., P2 procedure) or other beam management procedure in which a beam report is generated. 
     For each transmit beam of the m-TRP RAN entity received by the UE  1200 , the beam manager circuitry  1244  may be configured to obtain a respective beam quality metric (e.g., RSRP, SINR, etc.)  1224  on one or more of a plurality of receive beams of the antenna array(s)  1230 . The beam quality metrics  1224  may be stored, for example, in memory  1205 . In some examples, the beam manager circuitry  1244  may be configured to obtain a respective beam quality metric  1244  of each transmit beam on a corresponding one of the plurality of receive beams. For example, the beam manager circuitry  1244  may be configured to measure the respective RSRP of each transmit beam associated with a particular TRP on a corresponding one of the receive beams selected for that particular TRP during initial cell access (e.g., a P1 procedure). 
     In other examples, the beam manager circuitry  1244  may be configured to obtain the respective beam quality metric  1224  on each of the plurality of receive beams in parallel or serially during a respective measurement period. For example, the beam manager circuitry  1244  may be configured to utilize a Butler matrix to obtain the beam quality metrics  1224  on each of the receive beams in parallel. The receive beams may include all receive beams on all antenna arrays  1230  (antenna panels) of the UE  1200  or a subset of the receive beams or a subset of the antenna arrays. The beam quality metrics  1224  may be obtained, for example, by performing measurements on the transmit beams utilizing respective beam reference signals (e.g., SSBs or CSI-RSs) carried on the transmit beams. 
     The beam manager circuitry  1244  may further be configured to generate a respective beam quality metric vector for each of the transmit beams. For example, the beam manager circuitry  1244  may place all obtained beam quality metric values  1224  for each of the transmit beams in a respective beam quality metric vector. In some examples, each beam quality metric vector corresponds to an RSRP vector. In some examples, the RSRP vectors for the transmit beams indicates a mutual interference between the transmit beams as observed at the UE  1200 . 
     The beam manager circuitry  1244  may further be configured to generate a beam report (e.g., an L1 measurement report) including the beam quality metrics (e.g., RSRP values)  1224  for one or more transmit beams. The beam manager circuitry  1244  may further be configured to transmit the beam report to the m-TRP RAN entity via the communication and processing circuitry  1242  and transceiver  1210 . 
     In some examples, the beam report may include the beam quality metric (e.g., RSRP)  1224  of one or more of the transmit beams. For example, the beam report may include the beam quality metric of the transmit beam(s) having the highest RSRP. In this example, the beam quality metrics  1244  may include initial beam quality metrics obtained, for example, during a P2 procedure, and the beam report may correspond to an initial beam report. 
     In other examples, the beam manager circuitry  1244  may generate the beam report including an indication of a plurality of beam groups. The beam report including the indication of the plurality of beam groups may be generated during the P2 procedure or other subsequent beam management procedure. In examples in which the beam report is generated during a P2 procedure, the beam report includes the indication of the plurality of beam groups instead of the individual beam quality metric(s)  1224  of one or more transmit beams. The indication of the plurality of beam groups may include the plurality of beam groups or the beam quality metric vectors themselves. The beam manager circuitry  1244  may further be configured to execute beam manager instructions  1254  (e.g., software) stored in the computer-readable medium  1206  to implement one or more of the functions described herein. 
     The processor  1204  may further include TCI state manager circuitry  1246 , configured to manage TCI states  1220  and TCI state groups  1222  for the UE  1200 . The TCI state manager circuitry  1246  may correspond, for example, to any of the UE TCI state managers shown in  FIGS.  1  and/or  3 - 6   . 
     In some examples, the TCI state manager circuitry  1246  may be configured to receive a plurality of TCI states  1220  configured for the UE  1200  from the m-TRP RAN entity via the communication and processing circuitry  1242  and transceiver  1210 . The TCI state manager circuitry  1246  may further be configured to store the plurality of TCI states  1220  within, for example, memory  1205 . In some examples, the TCI state manager circuitry  1246  may receive an RRC configuration of the plurality of TCI states  1220 . The RRC configuration may include, for example, an RRC TCI states table including each of the TCI states  1220  configured for the UE  1200 . 
     The TCI state manager circuitry  1246  may further be configured to receive a plurality of TCI state groups  1222  configured for the UE  1200  from the m-TRP RAN entity via the communication and processing circuitry  1242  and the transceiver  1210 . The TCI state manager circuitry  1246  may further be configured to store the plurality of TCI state groups  1222  within, for example, memory  1205 . In some examples, the TCI state manager circuitry  1246  may receive an RRC configuration of the plurality of TCI state groups  1222 . The RRC configuration may include, for example, an RRC TCI state groups table including each of the TCI state groups  1222  configured for the UE  1200 . Each TCI state group  1222  may include, for example, a respective TCI state group identifier and a list of the TCI states  1220  (e.g., previously configured TCI states for the UE  1200 ) included within the respective TCI state group for each of the TCI state groups  1222 . 
     The TCI state manager circuitry  1246  may further be configured to determine the plurality of beam groups based on the beam quality metric vectors obtained by the beam manager circuitry  1244 . For example, from the beam quality metric vectors, the TCI state manager circuitry  1246  may select the beam groups such that each beam group includes a respective transmit beam associated with each of two or more of the TRPs of the multi-TRP RAN entity that have minimal mutual interference (e.g., minimum inter-beam interference) therebetween. In an example, the selected transmit beams for a particular beam group have the highest RSRP that are also associated with BPLs that have the minimum inter-beam interference experienced at the UE. 
     The TCI state manager circuitry  1246  may further be configured to receive an activation or deactivation message for one or more of the plurality of TCI state groups  1222 . The activation or deactivation message may be, for example, a MAC-CE. In some examples, the TCI state manager circuitry  1246  may be configured to receive an activation message that activates a set of active TCI state groups. In some examples, the set of active TCI state groups includes up to eight active TCI state groups that may be selected from for multi-stream PDSCH transmissions. 
     The TCI state manager circuitry  1246  may further be configured to receive control information (e.g., DCI) including a selected active TCI state group for a multi-stream PDSCH communication. The control information may further include scheduling information scheduling the multi-stream PDSCH communication. In some examples, the DCI may include a plurality of bits indicating the selected TCI state group for the multi-stream PDSCH communication. For example, the DCI may include three bits indicating the selected TCI state group. The TCI state manager circuitry  1246  may further operate in coordination with the communication and processing circuitry  1242  and beam manager circuitry  1244  to receive the SDM multi-stream PDSCH communication utilizing the selected active TCI state. The TCI state manager circuitry  1246  may further be configured to execute TCI state manager instructions  1256  (e.g., software) stored in the computer-readable medium  1206  to implement one or more of the functions described herein. 
       FIG.  13    is a flow chart  1300  illustrating an example of a method for TCI state management for multi-stream communication at a user equipment (UE) according to some aspects. As described below, some or all illustrated features may be omitted in a particular implementation within the scope of the present disclosure, and some illustrated features may not be required for implementation of all aspects. In some examples, the method may be performed by the UE  1200 , as described above and illustrated in  FIG.  12   , by a processor or processing system, or by any suitable means for carrying out the described functions. 
     At block  1302 , the UE may obtain a respective beam quality metric for each transmit beam of a plurality of transmit beams associated with a radio access network (RAN) entity. In some examples, the beam quality metric may include at least one of a reference signal received power (RSRP) or a signal-to-interference-plus-noise ratio (SINR). In some examples, the UE may receive a respective beam reference signal (e.g., SSB or CSI-RS) on each of the plurality of transmit beams, and the respective beam quality metric for each of the plurality of transmit beams is obtained based on the respective beam reference signal. In some examples, each of the plurality of transmit beams corresponds to one of a plurality of transmission and reception points (TRPs) associated with the RAN entity. 
     In some examples, the UE may, for each of the plurality of transmit beams, obtain a respective individual beam quality metric on each receive beam of a plurality of receive beams on the UE during a measurement period to produce a respective beam quality metric vector. In some examples, each of the plurality of receive beams is associated with a respective one of a plurality of antenna panels on the UE. In some examples, the beam quality metric includes the RSRP and each of the respective beam quality metric vectors includes an RSRP vector. The RSRP vectors for each of the plurality of transmit beams may indicate a respective mutual interference between each of the plurality of transmit beams. 
     In some examples, the UE may receive the plurality of transmit beams during a beam refinement (e.g., P2) procedure or other subsequent beam management procedure. In some examples, each of the plurality of transmit beams is associated with a frequency band selected from FR2, FR4-a, FR4-1, FR4, or FR5. For example, the beam manager circuitry  1244 , together with the communication and processing circuitry  1242 , transceiver  1210 , and antenna array(s)  1230 , shown and described above in connection with  FIG.  12   , may provide a means to obtain the respective beam quality metric for each transmit beam. 
     At block  1304 , the UE may transmit, to the RAN entity, a beam report indicating a plurality of beam groups based on the respective beam quality metrics. Each of the plurality of beam groups includes two or more of the plurality of transmit beams. In some examples, the beam report includes the respective beam quality metric vector for each of the plurality of transmit beams. In some examples, the beam report includes the plurality of beam groups. In this example, the UE may further identify the plurality of beam groups based on the respective beam quality metrics (e.g., the beam quality metric vectors). In some examples, the beam report may include an L1 measurement report. For example, the beam manager circuitry  1244 , together with the communication and processing circuitry  1242 , the TCI state manager circuitry  1246 , the transceiver  1210  and antenna array  1230  shown and described above in connection with  FIG.  12    may provide a means to transmit the beam report to the RAN entity. 
     At block  1306 , the UE may receive, from the RAN entity, a plurality of transmission configuration indicator (TCI) state groups. Each of the plurality of TCI state groups corresponding to a respective one of the plurality of beam groups. In some examples, the UE may receive a radio resource control (RRC) configuration of the plurality of TCI state groups. 
     In some examples, the UE may further receive a plurality of TCI states, each associated with a respective one of the plurality of transmit beams. Each of the plurality of TCI state groups can include a respective one of the plurality of TCI states for each of the plurality of transmit beams within the respective one of the plurality of beam groups. For example, the UE may receive, from the RAN entity, a radio resource control (RRC) configuration of the plurality of TCI states. In some examples, the UE may further obtain a respective initial beam quality metric for each of the plurality of transmit beams and transmit, to the RAN entity, an initial beam report including the respective initial beam quality metric of at least one transmit beam of the plurality of transmit beams. The UE may then receive, from the RAN entity, the plurality of TCI states in response to the initial beam report. For example, the TCI state manager circuitry  1246 , together with the communication and processing circuitry  1242 , the transceiver  1210 , and the antenna array  1230 , shown and described above in connection with  FIG.  12    may provide a means to receive the plurality of TCI state groups. 
       FIG.  14    is a flow chart  1400  illustrating another example of a method for TCI state management for multi-stream communication at a UE according to some aspects. As described below, some or all illustrated features may be omitted in a particular implementation within the scope of the present disclosure, and some illustrated features may not be required for implementation of all aspects. In some examples, the method may be performed by the UE  1200 , as described above and illustrated in  FIG.  12   , by a processor or processing system, or by any suitable means for carrying out the described functions. 
     At block  1402 , the UE may receive, from a radio access network (RAN) entity, a plurality of transmission configuration indicator (TCI) state groups. Each of the plurality of TCI state groups corresponding to a respective one of a plurality of beam groups. In some examples, the UE may receive a radio resource control (RRC) configuration of the plurality of TCI state groups. In some examples, each of the plurality of beam groups includes two or more of a plurality of transmit beams associated with the RAN entity. In some examples, each of the plurality of transmit beams corresponds to one of a plurality of transmission and reception points (TRPs) associated with the RAN entity. In some examples, each of the plurality of transmit beams is associated with a frequency band selected from FR2, FR4-a, FR4-1, FR4, or FR5. 
     In some examples, the UE may further receive a plurality of TCI states, each associated with a respective one of the plurality of transmit beams. Each of the plurality of TCI state groups can include a respective one of the plurality of TCI states for each of the plurality of transmit beams within the respective one of the plurality of beam groups. For example, the UE may receive, from the RAN entity, a radio resource control (RRC) configuration of the plurality of TCI states. For example, the TCI state manager circuitry  1246 , together with the communication and processing circuitry  1242 , the transceiver  1210 , and the antenna array  1230 , shown and described above in connection with  FIG.  12    may provide a means to receive the plurality of TCI state groups. 
     At block  1404 , the UE may receive, from the RAN entity, an activation message activating a set of active TCI state groups of the plurality of TCI state groups. In some examples, the activation message includes a medium access control-control element (MAC-CE). In some examples, the set of active TCI state groups includes up to eight of the plurality of TCI state groups. For example, the TCI state manager circuitry  1246 , together with the communication and processing circuitry  1242 , the transceiver  1210 , and the antenna array  1230 , shown and described above in connection with  FIG.  12    may provide a means to receive the activation message. 
     At block  1406 , the UE may receive, from the RAN entity, control information including an active TCI state group of the set of active TCI state groups associated with an assignment of resources for spatial division multiplexing of a plurality of streams to the UE. In some examples, the control information includes three bits indicating the active TCI state group. In some examples, the UE may further receive each of the plurality of streams from a different respective one of the plurality of TRPs using an active beam group of the plurality of beam groups associated with the active TCI state group. For example, the TCI state manager circuitry  1246 , together with the communication and processing circuitry  1242 , the transceiver  1210 , and the antenna array  1230  shown and described above in connection with  FIG.  12    may provide a means to receive the control information including an active TCI state group. 
     In one configuration, the UE  1200  includes means for performing the various functions and processes described in relation to  FIGS.  13  and  14   . In one aspect, the aforementioned means may be the processor  1204  shown in  FIG.  12    configured to perform the functions recited by the aforementioned means. In another aspect, the aforementioned means may be a circuit or any apparatus configured to perform the functions recited by the aforementioned means. 
     Of course, in the above examples, the circuitry included in the processor  1204  is merely provided as an example, and other means for carrying out the described functions may be included within various aspects of the present disclosure, including but not limited to the instructions stored in the computer-readable storage medium  1206 , or any other suitable apparatus or means described in any one of the  FIG.  1 ,  3 - 6 ,  8   , or  9 , and utilizing, for example, the processes and/or algorithms described herein in relation to  FIGS.  13  and  14   . 
       FIG.  15    is a conceptual diagram illustrating an example of a hardware implementation for an exemplary RAN entity  1500  employing a processing system  1514 . For example, the RAN entity  1500  may correspond to any of the base stations (e.g., gNBs), TRPs (e.g., combined TRP and base station in a RRH configuration), or other scheduling entities illustrated in any one or more of  FIG.  1 ,  3 - 6 ,  8   , or  9 . 
     In accordance with various aspects of the disclosure, an element, or any portion of an element, or any combination of elements may be implemented with a processing system  1514  that includes one or more processors  1504 . The processing system  1514  may be substantially the same as the processing system  1114  illustrated in  FIG.  11   , including a bus interface  1508 , a bus  1502 , memory  1505 , a processor  1504 , and a computer-readable medium  1506 . Furthermore, the RAN entity  1500  may include an optional user interface  1512  and a transceiver  1510  substantially similar to those described above in  FIG.  11   . In some examples, the transceiver  1510  may include a phase-shifter  1516  for digital and/or analog beamforming via one or more antenna array(s)  1530 . The processor  1504 , as utilized in a RAN entity  1500 , may be used to implement any one or more of the processes described below. 
     In some aspects of the disclosure, the processor  1504  may include circuitry configured for various functions. For example, the processor  1504  may include resource assignment and scheduling circuitry  1542 , configured to generate, schedule, and modify a resource assignment or grant of time-frequency resources (e.g., a set of one or more resource elements). For example, the resource assignment and scheduling circuitry  1542  may schedule time-frequency resources within a plurality of time division duplex (TDD) and/or frequency division duplex (FDD) subframes, slots, and/or mini-slots to carry user data traffic and/or control information to and/or from multiple UEs. 
     In some examples, the resource assignment and scheduling circuitry  1542  may be configured to schedule resources for the transmission of a plurality of transmit beams, each carrying a beam reference signal, from a plurality of TRPs associated with the RAN entity  1500 . For example, the transmit beams may be scheduled during a beam refinement procedure or other beam management procedure in which a beam report  1524  may be received from a UE. The resource assignment and scheduling circuitry  1542  may schedule at least one transmit beam from each TRP or from a subset of the TRPs (e.g., active TRPs for the UE). The resource assignment and scheduling circuitry  1542  may further be configured to schedule transmission by the UE of the beam report  1524  to the RAN entity  1500 . In addition, the resource assignment and scheduling circuitry  1542  may be configured to schedule transmission of multiple spatially division multiplexed data streams, each from a respective TRP, to the UE. 
     The resource assignment and scheduling circuitry  1542  may further be configured to schedule resources for the transmission of an RRC configuration of TCI states to a UE, the transmission of an RRC configuration of TCI state groups to a UE, the transmission of an activation message (e.g., MAC-CE) activating a set of active TCI state groups to the UE, and the transmission of control information (e.g., DCI) including an active TCI state group selected for the transmission of the multiple spatially division multiplexed data streams. The resource assignment and scheduling circuitry  1542  may further be configured to execute resource assignment and scheduling software  1552  stored in the computer-readable medium  1506  to implement one or more of the functions described herein. 
     The processor  1504  may further include communication and processing circuitry  1544 , configured to communicate with the UE. In some examples, the communication and processing circuitry  1544  may include one or more hardware components that provide the physical structure that performs processes related to wireless communication (e.g., signal reception and/or signal transmission) and signal processing (e.g., processing a received signal and/or processing a signal for transmission). 
     In some examples, the communication and processing circuitry  1544  may be configured to receive and process uplink beamformed signals at a mmWave frequency or a sub-6 GHz frequency via the transceiver  1510  and the antenna array  1530  (e.g., using the phase-shifter  1516 ). In addition, the communication and processing circuitry  1544  may be configured to generate and transmit uplink beamformed signals at a mmWave frequency or a sub-6 GHz frequency via the transceiver  1510  and antenna array  1530  (e.g., using the phase-shifter  1516 ). For example, the communication and processing circuitry  1544  may be configured for multi-stream communication with the UE entity via spatial division multiplexing (SDM) of the multiple streams on corresponding multiple beam pair links (BPLs) between the UE and respective TRPs of the RAN entity  1500 . 
     The communication and processing circuitry  1544  may further be configured to transmit a plurality of transmit beams from a plurality of TRPs of the RAN entity  1500  via the antenna arrays  1530  and transceiver  1510 . Each of the transmit beams may carry a respective beam reference signal (e.g., an SSB or CSI-RS). The communication and processing circuitry  1544  may further be configured to receive a beam report  1524  (e.g., an L1 measurement report) from the UE. The beam report  1524  may further be stored, for example, in memory  1505 . The communication and processing circuitry  1544  may further be configured to transmit the plurality of TCI states (e.g., the RRC configuration of the plurality of TCI states), the plurality of TCI state groups (e.g., the RRC configuration of the plurality of TCI state groups), the activation message (e.g., the MAC-CE) activating a set of active TCI state groups of the plurality of TCI state groups, and the control information (e.g., DCI) including the active TCI state group selected for SDM of the multiple streams to the UE. The communication and processing circuitry  1544  may further be configured to execute communication and processing software  1554  stored in the computer-readable medium  1506  to implement one or more of the functions described herein. 
     The processor  1504  may further include beam manager circuitry  1546 , configured to perform beam management for SDM multi-stream communication. The beam manager circuitry  1546  may be configured to perform beam management for SDM multi-stream communication during a beam refinement procedure (e.g., P2 procedure) or other beam management procedure in which a beam report is generated. The beam manager circuitry  1546  may be configured to operate together with the resource assignment and scheduling circuitry  1542  and communication and processing circuitry  1544  to generate and transmit the plurality of transmit beams to the UE. The beam manager circuitry  1546  may further be configured to receive a beam report  1524  from the UE. 
     In some examples, the beam report  1524  may include a beam quality metric (e.g., RSRP) of one or more of the transmit beams. For example, the beam report  1524  may include the beam quality metric of the transmit beam(s) having the highest RSRP. In this example, the beam quality metrics may include initial beam quality metrics obtained, for example, during a P2 procedure, and the beam report  1524  may correspond to an initial beam report. 
     In other examples, the beam report  1524  may include an indication of a plurality of beam groups  1526 . The beam report  1524  including the indication of the plurality of beam groups  1526  may be generated during the P2 procedure or other subsequent beam management procedure. In examples in which the beam report  1524  is generated during a P2 procedure, the beam report  1524  includes the indication of the plurality of beam groups  1526  instead of the individual beam quality metric(s) of one or more transmit beams. In some examples, the indication of the plurality of beam groups may include the plurality of beam groups. In other examples, the indication of the plurality of beam groups may include a respective beam quality metric vector for each of the plurality of transmit beams. Each beam quality metric vector may include a respective beam quality metric obtained during a respective measurement period in parallel or serially on each of a plurality of receive beams of the UE. For example, the beam quality metric vectors may include RSRP vectors. The beam manager circuitry  1546  may further be configured to execute beam manager instructions  1556  (e.g., software) stored in the computer-readable medium  1506  to implement one or more of the functions described herein. 
     The processor  1504  may further include TCI state manager circuitry  1548 , configured to manage TCI states  1520  and TCI state groups  1522  for a UE. The TCI state manager circuitry  1548  may correspond, for example, to any of the RAN entity TCI state managers shown in  FIGS.  1  and/or  3 - 6   . 
     In some examples, the TCI state manager circuitry  1548  may be configured to configure a plurality of TCI states  1520  for the UE and to transmit the plurality of TCI states  1520  to the UE via the communication and processing circuitry  1544 , the transceiver  1510 , and the antenna array  1530 . The TCI state manager circuitry  1548  may further be configured to store the plurality of TCI states  1520  within, for example, memory  1505 . In some examples, the TCI state manager circuitry  1548  may be configured to transmit an RRC configuration of the plurality of TCI states  1520 . The RRC configuration may include, for example, an RRC TCI states table including each of the TCI states  1520  configured for the UE. 
     The TCI state manager circuitry  1548  may be configured to configure the TCI states  1520  for the UE based on a beam report  1524  received from the UE during, for example, a P2 procedure or other beam management procedure. In some examples, the beam report may be the initial beam report including initial beam quality metrics (e.g., the beam quality metric of the transmit beam(s) having the highest RSRP). In other examples, the beam report  1524  may be an enhanced beam report including a respective beam quality metric vector for each of the plurality of transmit beams. 
     The TCI state manager circuitry  1548  may further be configured to group the plurality of transmit beams into a plurality of beam groups  1526 . The beam groups  1526  may be stored, for example, in memory  1505 . Each transmit beam of the plurality of transmit beams may correspond to a respective one of a plurality of TRPs associated with the RAN entity. Each of the plurality of beam groups  1526  may include a single transmit beam from each of two or more of the TRPs for multi-stream communication. 
     The TCI state manager circuitry  1548  may group the plurality of transmit beams into the plurality of beam groups  1526  based on a beam report  1524 . In some examples, the beam report  1524  may be the same beam report utilized to configure the plurality of TCI states (e.g., the beam report  1524  received during the P2 procedure) or a subsequently received beam report  1524  during a subsequent beam management procedure. In some examples, the beam report  1524  may include the plurality of beam groups  1526  and the TCI state manager circuitry  1548  may group the transmit beams into the plurality of beam groups  1526  in accordance with the beam groups included in the beam report  1524 . In other examples, the beam report  1524  may include a respective beam quality metric vector for each of the plurality of transmit beams. For example, from the beam quality metric vectors, the TCI state manager  1548  may group the transmit beams into the beam groups  1526  such that each beam group  1526  includes a respective transmit beam associated with each of two or more of the TRPs of the multi-TRP RAN entity  1500  that have minimal mutual interference (e.g., minimum inter-beam interference) therebetween. In an example, the selected transmit beams for a particular beam group have the highest RSRP that are also associated with BPLs that have the minimum inter-beam interference experienced at the UE. 
     The TCI state manager circuitry  1548  may then configure a plurality of TCI state groups  1522  for the UE, each corresponding to a different respective beam group  1526 , and transmit the TCI state groups  1522  to the UE via the communication and processing circuitry  1544 , the transceiver  1510 , and the antenna array  1530 . The TCI state manager circuitry  1548  may further be configured to store the plurality of TCI state groups  1522  within, for example, memory  1505 . In some examples, the TCI state manager circuitry  1548  may transmit an RRC configuration of the plurality of TCI state groups  1522 . The RRC configuration may include, for example, an RRC TCI state groups table including each of the TCI state groups  1522  configured for the UE. Each TCI state group  1522  may include, for example, a respective TCI state group identifier and a list of the TCI states  1520  (e.g., previously configured TCI states for the UE) included within the respective TCI state group for each of the TCI state groups  1522 . 
     The TCI state manager circuitry  1548  may further be configured to transmit an activation or deactivation message for one or more of the plurality of TCI state groups  1522 . The activation or deactivation message may be, for example, a MAC-CE. In some examples, the TCI state manager circuitry  1548  may be configured to transmit an activation message that activates a set of active TCI state groups. In some examples, the set of active TCI state groups includes up to eight active TCI state groups that may be selected from for multi-stream PDSCH transmissions. The TCI state manager circuitry  1548  may select the active TCI state groups based on, for example, a mobility pattern of the UE. 
     The TCI state manager circuitry  1548  may further be configured to transmit control information (e.g., DCI) including a selected active TCI state group for a multi-stream PDSCH communication. The control information may further include scheduling information scheduling the multi-stream PDSCH communication. In some examples, the DCI may include a plurality of bits indicating the selected TCI state group for the multi-stream PDSCH communication. For example, the DCI may include three bits indicating the selected TCI state group. The TCI state manager circuitry  1548  may further operate in coordination with the communication and processing circuitry  1544  and beam manager circuitry  1546  to transmit the SDM multi-stream PDSCH communication utilizing the selected active TCI state. The TCI state manager circuitry  1548  may further be configured to execute TCI state manager instructions  1556  (e.g., software) stored in the computer-readable medium  1506  to implement one or more of the functions described herein. 
       FIG.  16    is a flow chart  1600  illustrating an example of a method for TCI state management for multi-stream communication at a radio access network (RAN) entity according to some aspects. As described below, some or all illustrated features may be omitted in a particular implementation within the scope of the present disclosure, and some illustrated features may not be required for implementation of all aspects. In some examples, the method may be performed by the RAN entity  1500 , as described above and illustrated in  FIG.  15   , by a processor or processing system, or by any suitable means for carrying out the described functions. 
     At block  1602 , the RAN entity may receive, from a user equipment (UE) in wireless communication with the RAN entity, a beam report indicating a plurality of beam groups, each including two or more of a plurality of transmit beams associated with the RAN entity. In some examples, each of the plurality of transmit beams corresponds to one of a plurality of transmission and reception points (TRPs) associated with the RAN entity. In some examples, the beam report includes a respective beam quality metric vector (e.g., an RSRP vector) for each of the plurality of transmit beams. For example, each of the respective beam quality metric vectors may include a respective individual beam quality metric obtained on each receive beam of a plurality of receive beams on the UE during a measurement period. In some examples, the beam report includes the plurality of beam groups. In some examples, the beam report may include an L1 measurement report. In some examples, each of the plurality of transmit beams is associated with a frequency band selected from FR2, FR4-a, FR4-1, FR4, or FR5. For example, the beam manager circuitry  1546 , together with the communication and processing circuitry  1544 , transceiver  1510 , and antenna array(s)  1530 , shown and described above in connection with  FIG.  15   , may provide a means to receive the beam report from the UE. 
     At block  1604 , the RAN entity may group the plurality of transmit beams into the plurality of beam groups based on the beam report. In examples in which the beam report includes the beam groups, the RAN entity may group the plurality of transmit beams into the plurality of beam groups in accordance with the plurality of beam groups included in the beam report. In examples in which the beam report includes a respective beam quality metric vector for each of the plurality of transmit beams, the RAN entity may group the plurality of transmit beams into the plurality of beam groups based on the beam quality metric vectors. For example, the TCI state manager circuitry  1548  shown and described above in connection with  FIG.  15   , may provide a means to group the transmit beams into beam groups. 
     At block  1606 , the RAN entity may transmit, to the UE, a plurality of transmission configuration indicator (TCI) state groups. Each of the plurality of TCI state groups corresponding to a respective one of the plurality of beam groups. In some examples, the RAN entity may transmit a radio resource control (RRC) configuration of the plurality of TCI state groups. 
     In some examples, the RAN entity may further transmit, to the UE, a plurality of TCI states, each associated with a respective one of the plurality of transmit beams. Each of the plurality of TCI state groups can include a respective one of the plurality of TCI states for each of the plurality of transmit beams within the respective one of the plurality of beam groups. For example, the RAN entity may transmit, to the UE, a radio resource control (RRC) configuration of the plurality of TCI states. In some examples, the RAN entity may further receive, from the UE, an initial beam report including a respective initial beam quality metric of at least one transmit beam of the plurality of transmit beams and transmit, to the UE, the plurality of TCI states in response to the initial beam report. For example, the TCI state manager circuitry  1548 , together with the communication and processing circuitry  1544 , the transceiver  1510 , and the antenna array  1530 , shown and described above in connection with  FIG.  15    may provide a means to transmit the plurality of TCI state groups. 
       FIG.  17    is a flow chart  1700  illustrating another example of a method for TCI state management for multi-stream communication at a RAN entity according to some aspects. As described below, some or all illustrated features may be omitted in a particular implementation within the scope of the present disclosure, and some illustrated features may not be required for implementation of all aspects. In some examples, the method may be performed by the RAN entity  1500 , as described above and illustrated in  FIG.  15   , by a processor or processing system, or by any suitable means for carrying out the described functions. 
     At block  1702 , the RAN entity may transmit, to a UE, a plurality of transmission configuration indicator (TCI) state groups. Each of the plurality of TCI state groups corresponding to a respective one of a plurality of beam groups. In some examples, the RAN entity may transmit a radio resource control (RRC) configuration of the plurality of TCI state groups. In some examples, each of the plurality of beam groups includes two or more of a plurality of transmit beams associated with the RAN entity. In some examples, each of the plurality of transmit beams corresponds to one of a plurality of transmission and reception points (TRPs) associated with the RAN entity. In some examples, each of the plurality of transmit beams is associated with a frequency band selected from FR2, FR4-a, FR4-1, FR4, or FR5. 
     In some examples, the RAN entity may further transmit, to the UE, a plurality of TCI states, each associated with a respective one of the plurality of transmit beams. Each of the plurality of TCI state groups can include a respective one of the plurality of TCI states for each of the plurality of transmit beams within the respective one of the plurality of beam groups. For example, the RAN entity may transmit, to the UE, a radio resource control (RRC) configuration of the plurality of TCI states. For example, the TCI state manager circuitry  1548 , together with the communication and processing circuitry  1544 , the transceiver  1510 , and the antenna array  1530 , shown and described above in connection with  FIG.  15    may provide a means to transmit the plurality of TCI state groups. 
     At block  1704 , the RAN entity may transmit, to the UE, an activation message activating a set of active TCI state groups of the plurality of TCI state groups. In some examples, the activation message includes a medium access control-control element (MAC-CE). In some examples, the set of active TCI state groups includes up to eight of the plurality of TCI state groups. For example, the TCI state manager circuitry  1548 , together with the communication and processing circuitry  1544 , the transceiver  1510 , and the antenna array  1530 , shown and described above in connection with  FIG.  15    may provide a means to transmit the activation message. 
     At block  1706 , the RAN entity may transmit, to the UE, control information including an active TCI state group of the set of active TCI state groups associated with an assignment of resources for spatial division multiplexing of a plurality of streams to the UE. In some examples, the control information includes three bits indicating the active TCI state group. In some examples, the RAN entity may further transmit each of the plurality of streams from a different respective one of the plurality of TRPs using an active beam group of the plurality of beam groups associated with the active TCI state group. For example, the TCI state manager circuitry  1548 , together with the communication and processing circuitry  1544 , the transceiver  1510 , and the antenna array  1530 , shown and described above in connection with  FIG.  15    may provide a means to transmit the control information including an active TCI state group. 
     In one configuration, the RAN entity  1500  includes means for performing the various functions and processes described in relation to  FIGS.  16  and  17   . In one aspect, the aforementioned means may be the processor  1504  shown in  FIG.  15    configured to perform the functions recited by the aforementioned means. In another aspect, the aforementioned means may be a circuit or any apparatus configured to perform the functions recited by the aforementioned means. 
     Of course, in the above examples, the circuitry included in the processor  1504  is merely provided as an example, and other means for carrying out the described functions may be included within various aspects of the present disclosure, including but not limited to the instructions stored in the computer-readable storage medium  1506 , or any other suitable apparatus or means described in any one of the  FIG.  1 ,  3 - 6 ,  8   , or  9 , and utilizing, for example, the processes and/or algorithms described herein in relation to  FIGS.  16  and  17   . 
     The following provides an overview of aspects of the present disclosure: 
     Aspect 1: A method for wireless communication at a user equipment (UE) in a wireless communication network, the method comprising: obtaining a respective beam quality metric for each transmit beam of a plurality of transmit beams associated with a radio access network (RAN) entity; transmitting, to the RAN entity, a beam report indicating a plurality of beam groups based on the respective beam quality metrics, each of the plurality of beam groups comprising two or more of the plurality of transmit beams; and receiving, from the RAN entity, a plurality of transmission configuration indicator (TCI) state groups, each of the plurality of TCI state groups corresponding to a respective one of the plurality of beam groups. 
     Aspect 2: The method of aspect 1, wherein the receiving, from the RAN entity, the at least one TCI state group further comprises: receiving, from the RAN entity, a radio resource control (RRC) configuration of the plurality of TCI state groups. 
     Aspect 3: The method of aspect 1 or 2, further comprising: receiving, from the RAN entity, an activation message activating a set of active TCI state groups of the plurality of TCI state groups. 
     Aspect 4: The method of aspect 3, wherein the activation message comprises a medium access control-control element (MAC-CE). 
     Aspect 5: The method of aspect 3 or 4, wherein the set of active TCI state groups comprises up to eight of the plurality of TCI state groups. 
     Aspect 6: The method of any of aspects 1 through 5, further comprising: receiving, from the RAN entity, control information comprising an active TCI state group of the set of active TCI state groups associated with an assignment of resources for spatial division multiplexing of a plurality of streams to the UE. 
     Aspect 7: The method of aspect 6, wherein each of the plurality of transmit beams corresponds to one of a plurality of transmission and reception points (TRPs) associated with the RAN entity, and further comprising: receiving each of the plurality of streams from a different respective one of the plurality of TRPs using an active beam group of the plurality of beam groups associated with the active TCI state group. 
     Aspect 8: The method of aspect 6 or 7, wherein the control information comprises three bits indicating the active TCI state group. 
     Aspect 9: The method of any of aspects 1 through 8, further comprising: receiving a plurality of TCI states, each associated with a respective one of the plurality of transmit beams, each of the plurality of TCI state groups comprises a respective one of the plurality of TCI states for each of the plurality of transmit beams within the respective one of the plurality of beam groups. 
     Aspect 10: The method of aspect 9, wherein the receiving the plurality of TCI states further comprises: receiving, from the RAN entity, a radio resource control (RRC) configuration of the plurality of TCI states. 
     Aspect 11: The method of aspect 9 or 10, further comprising: obtaining a respective initial beam quality metric for each of the plurality of transmit beams; and transmitting, to the RAN entity, an initial beam report comprising the respective initial beam quality metric of at least one transmit beam of the plurality of transmit beams. 
     Aspect 12: The method of aspect 11, wherein the receiving, from the RAN entity, the plurality of TCI states further comprises: receiving, from the RAN entity, the plurality of TCI states in response to the initial beam report. 
     Aspect 13: The method of any of aspects 1 through 12, wherein the obtaining the respective beam quality metric for each transmit beam of the plurality of transmit beams comprises: for each of the plurality of transmit beams, obtaining a respective individual beam quality metric on each receive beam of a plurality of receive beams on the UE during a measurement period to produce a respective beam quality metric vector, wherein the beam report comprises the respective beam quality metric vector for each of the plurality of transmit beams. 
     Aspect 14: The method of any of aspects 1 through 13, wherein the transmitting, to the RAN entity, the beam report indicating a plurality of beam groups further comprises: identifying the plurality of beam groups based on the respective beam quality metrics; and including the plurality of beam groups within the beam report. 
     Aspect 15: The method of any of aspects 1 through 14, wherein each of the plurality of transmit beams is associated with a frequency band selected from FR2, FR4, FR4-a, FR4-1, or FR5. 
     Aspect 16: A user equipment (UE) configured for wireless communication comprising a processor, and a memory coupled to the processor, the processor and memory configured to perform a method of any one of aspects 1 through 15. 
     Aspect 17: A method for wireless communication at a radio access network (RAN) entity in a wireless communication network, the method comprising: receiving, from a user equipment (UE) in wireless communication with the RAN entity, a beam report indicating a plurality of beam groups, each comprising two or more of a plurality of transmit beams associated with the RAN entity; and transmitting, to the UE, a plurality of transmission configuration indicator (TCI) state groups, each of the plurality of TCI state groups corresponding to a respective one of the plurality of beam groups. 
     Aspect 18: The method of aspect 17, wherein the transmitting, to the UE, the at least one TCI state group further comprises: transmitting, to the UE, a radio resource control (RRC) configuration of the plurality of TCI state groups. 
     Aspect 19: The method of aspect 17 or 18, further comprising: transmitting, to the UE, an activation message activating a set of active TCI state groups of the plurality of TCI state groups. 
     Aspect 20: The method of aspect 19, wherein the activation message comprises a medium access control-control element (MAC-CE). 
     Aspect 21: The method of aspect 19 or 20, wherein the set of active TCI state groups comprises up to eight of the plurality of TCI state groups. 
     Aspect 22: The method of any of aspects 17 through 21, further comprising: transmitting, to the UE, control information comprising an active TCI state group of the set of active TCI state groups associated with an assignment of resources for spatial division multiplexing of a plurality of streams to the UE. 
     Aspect 23: The method of aspect 22, wherein each of the plurality of transmit beams corresponds to one of a plurality of transmission and reception points (TRPs) associated with the RAN entity, and further comprising: transmitting each of the plurality of streams from a different respective one of the plurality of TRPs using an active beam group of the plurality of beam groups associated with the active TCI state group. 
     Aspect 24: The method of aspect 22 or 23, wherein the control information comprises three bits indicating the active TCI state group. 
     Aspect 25: The method of any of aspects 17 through 24, further comprising: transmitting a plurality of TCI states, each associated with a respective one of the plurality of transmit beams, wherein each of the plurality of TCI state groups comprises a respective one of the plurality of TCI states for each of the plurality of transmit beams within the respective one of the plurality of beam groups. 
     Aspect 26: The method of aspect 25, wherein the transmitting the plurality of TCI states further comprises: receiving, from the UE, an initial beam report comprising a respective initial beam quality metric of at least one transmit beam of the plurality of transmit beams; and transmitting, to the UE, the plurality of TCI states in response to the initial beam report. 
     Aspect 27: The method of any of aspects 17 through 26, wherein the beam report comprises a respective beam quality metric vector for each of the plurality of transmit beams, each of the respective beam quality metric vectors comprising a respective individual beam quality metric obtained on each receive beam of a plurality of receive beams on the UE during a measurement period, and further comprising: grouping the plurality of transmit beams into the plurality of beam groups based on the respective beam quality metric vectors. 
     Aspect 28: The method of any of aspects 17 through 27, wherein the beam report comprises the plurality of beam groups, and further comprising: grouping the plurality of transmit beams into the plurality of beam groups in accordance with the plurality of beam groups included within the beam report. 
     Aspect 29: A radio access network (RAN) entity configured for wireless communication comprising a processor, and a memory coupled to the processor, the processor and memory configured to perform a method of any one of aspects 17 through 28. 
     Aspect 30: An apparatus configured for wireless communication comprising at least one means for performing a method of any one of aspects 1 through 15 or 17 through 28. 
     Aspect 31: A non-transitory computer-readable medium storing processor-executable code, comprising code for causing an apparatus to perform a method of any one of aspects 1 through 15 or 17 through 28. 
     Several aspects of a wireless communication network have been presented with reference to an exemplary implementation. As those skilled in the art will readily appreciate, various aspects described throughout this disclosure may be extended to other telecommunication systems, network architectures and communication standards. 
     By way of example, various aspects may be implemented within other systems defined by 3GPP, such as Long-Term Evolution (LTE), the Evolved Packet System (EPS), the Universal Mobile Telecommunication System (UMTS), and/or the Global System for Mobile (GSM). Various aspects may also be extended to systems defined by the 3rd Generation Partnership Project 2 (3GPP2), such as CDMA2000 and/or Evolution-Data Optimized (EV-DO). Other examples may be implemented within systems employing IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Ultra-Wideband (UWB), Bluetooth, and/or other suitable systems. The actual telecommunication standard, network architecture, and/or communication standard employed will depend on the specific application and the overall design constraints imposed on the system. 
     Within the present disclosure, the word “exemplary” is used to mean “serving as an example, instance, or illustration.” Any implementation or aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects of the disclosure. Likewise, the term “aspects” does not require that all aspects of the disclosure include the discussed feature, advantage or mode of operation. The term “coupled” is used herein to refer to the direct or indirect coupling between two objects. For example, if object A physically touches object B, and object B touches object C, then objects A and C may still be considered coupled to one another—even if they do not directly physically touch each other. For instance, a first object may be coupled to a second object even though the first object is never directly physically in contact with the second object. The terms “circuit” and “circuitry” are used broadly, and intended to include both hardware implementations of electrical devices and conductors that, when connected and configured, enable the performance of the functions described in the present disclosure, without limitation as to the type of electronic circuits, as well as software implementations of information and instructions that, when executed by a processor, enable the performance of the functions described in the present disclosure. 
     One or more of the components, steps, features and/or functions illustrated in  FIGS.  1 - 17    may be rearranged and/or combined into a single component, step, feature or function or embodied in several components, steps, or functions. Additional elements, components, steps, and/or functions may also be added without departing from novel features disclosed herein. The apparatus, devices, and/or components illustrated in  FIGS.  1 ,  3 - 6 ,  8 ,  9 ,  12   , and/or  15  may be configured to perform one or more of the methods, features, or steps described herein. The novel algorithms described herein may also be efficiently implemented in software and/or embedded in hardware. 
     It is to be understood that the specific order or hierarchy of steps in the methods disclosed is an illustration of exemplary processes. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the methods may be rearranged. The accompanying method claims present elements of the various steps in a sample order and are not meant to be limited to the specific order or hierarchy presented unless specifically recited therein. 
     The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the 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, wherein 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. 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 and b; a and c; b and c; and a, b, and c. 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.