Patent Publication Number: US-2022224387-A1

Title: Sub-band channel state information reporting for ultra-reliable low latency communications

Description:
TECHNICAL FIELD 
     The technology discussed below relates generally to wireless communication systems, and more particularly, to sub-band (SB) channel state information (SB-CSI) reporting, for example, for ultra-reliable low latency communications (URLLC). 
     INTRODUCTION 
     Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, broadcasts, etc. These wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc.). Examples of such multiple-access systems include 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) systems, LTE Advanced (LTE-A) systems, code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems, to name a few. 
     In some examples, a wireless multiple-access communication system may include a number of base stations (BSs), which are each capable of simultaneously supporting communication for multiple communication devices, otherwise known as user equipment (UEs). In an LTE or LTE-A network, a set of one or more base stations may define an eNodeB (eNB). In other examples (e.g., in a next generation, a new radio (NR), or 5G network), a wireless multiple access communication system may include a number of distributed units (DUs) (e.g., edge units (EUs), edge nodes (ENs), radio heads (RHs), smart radio heads (SRHs), transmission reception points (TRPs), etc.) in communication with a number of central units (CUs) (e.g., central nodes (CNs), access node controllers (ANCs), etc.), where a set of one or more DUs, in communication with a CU, may define an access node (e.g., which may be referred to as a BS, 5G NB, next generation NodeB (gNB or gNodeB), transmission reception point (TRP), etc.). A BS or DU may communicate with a set of UEs on downlink channels (e.g., for transmissions from a BS or DU to a UE) and uplink channels (e.g., for transmissions from a UE to BS or DU). 
     These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. NR (e.g., new radio or 5G) is an example of an emerging telecommunication standard. NR is a set of enhancements to the LTE mobile standard promulgated by 3GPP. NR is designed to better support mobile broadband Internet access by improving spectral efficiency, lowering costs, improving services, making use of new spectrum, and better integrating with other open standards using OFDMA with a cyclic prefix (CP) on the downlink (DL) and on the uplink (UL). To these ends, NR supports beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation. 
     For ultra-reliable low latency communications (URLLCs) applications reliability may be crucial. Generally, data is transmitted from a base station and delivered to a user equipment (UE) within two transmissions. The specified block error rate (BLER) for these data transmissions is 10 −5  which provides for a narrow margin particularly when interference exists. Interference may be a challenge for enabling URLLC applications while maintaining a specified quality of service. 
     BRIEF SUMMARY OF SOME EXAMPLES 
     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. 
     A method of wireless communication operable at a user equipment (UE) is provided. The method includes receiving a physical downlink shared channel (PDSCH) transmission from a base station. The method also includes transmitting either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission to the base station in response to a reception of the PDSCH transmission. The method further includes determining whether to transmit a sub-band (SB) channel state information (SB-CSI) report to the base station based on whether the ACK transmission is transmitted to the base station or whether the NACK transmission is transmitted to the base station. 
     In some aspects, transmitting either the ACK transmission or the NACK transmission to the base station in response to the reception of the PDSCH transmission may include transmitting either the ACK transmission or the NACK transmission to the base station based on an ability of the UE to decode the PDSCH transmission. In some aspects, the method may further include receiving downlink control information (DCI) associated with the PDSCH transmission, where the DCI indicates a first modulation coding scheme (MCS) value associated the PDSCH transmission, configuring the reception of the DCI for receiving the PDSCH transmission, and measuring a second MCS value associated with the received PDSCH transmission. In some aspects, transmitting either the ACK transmission or the NACK transmission to the base station in response to the reception of the PDSCH transmission may include transmitting either the ACK transmission or the NACK transmission to the base station based on a threshold difference between the first MCS value and the second MCS value. 
     In some aspects, the method may further include transmitting the SB-CSI report to the base station when the ACK transmission is transmitted to the base station, and transmitting the SB-CSI report to the base station when the NACK transmission is transmitted to the base station. In some aspects, the method may further include transmitting the SB-CSI report to the base station when the NACK transmission is transmitted to the base station, or abstaining from transmitting the SB-CSI report when the ACK transmission is transmitted to the base station. In some aspects, when determining to transmit the SB-CSI report to the base station, the method may further include determining to include with the SB-CSI report SB reporting with full resolution, where the SB reporting with full resolution indicates one or more channel quality information (CQI) values each associated with a sub-band of a plurality of sub-bands utilized by the PDSCH transmission, or determining to include with the SB-CSI report SB reporting without full resolution, wherein SB reporting without full resolution indicates one or more spatial differential CQI values each associated with an offset level, and where the offset level includes a difference between a CQI value associated with a sub-band of the plurality of sub-bands utilized by the PDSCH transmission and an average CQI value associated with the plurality of sub-bands utilized by the PDSCH transmission. In some aspects, the one or more CQI values may include at least one of a CQI index, a modulation scheme, a code rate, or an efficiency. 
     In some aspects, determining to include with the SB-CSI report SB reporting with full resolution or determining to include with the SB-CSI report SB reporting without full-resolution is based on at least a quality of a decoding of the PDSCH transmission. In some aspect, the method may further include receiving a control message from the base station indicating whether to include with the SB-CSI report the SB reporting with full resolution or the SB reporting without full resolution. In some aspects, determining whether to include with the SB-CSI report the SB reporting with full resolution or the SB reporting without full resolution is based at least on the control message. In some aspects, the control message may include at least one of a radio resource control (RRC) message, a medium access control (MAC) control element (MAC-CE), or a downlink control information (DCI). 
     In some aspects, when determining to include with the SB-CSI report the SB reporting with full resolution, the method may further include determining whether to include a rank indication per sub-band with the SB reporting with full resolution, where the rank indication per sub-band indicates a quantity of sub-bands utilized by the PDSCH transmission that are able to be supported by the UE. In some aspects, at least one of the ACK transmission or the NACK transmission may include an indication that the rank indication is to be included with the SB reporting with full resolution. In some aspects, the method may further include receiving downlink control information (DCI) associated with the PDSCH transmission, where the DCI indicates a first modulation coding scheme (MCS) value associated with the PDSCH transmission, configuring the reception of the DCI for receiving the PDSCH transmission, and measuring a second MCS value associated with the received PDSCH transmission. In some aspects, determining whether to include the rank indication per sub-band with the SB reporting with full resolution is based on a threshold difference between the first MCS value and the second MCS value. 
     A method of wireless communication operable at a base station is provided. The method includes transmitting a physical downlink shared channel (PDSCH) transmission to a user equipment (UE). The method also includes receiving either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission from the UE in response to the transmission of the PDSCH transmission. The method further includes receiving a sub-band (SB) channel state information (SB-CSI) report from the UE based on whether the ACK transmission is transmitted by the UE or the NACK transmission is transmitted by the UE. 
     In some aspects, receiving either the ACK transmission or the NACK transmission from the UE in response to the transmission of the PDSCH transmission may include receiving either the ACK transmission or the NACK transmission from the UE based on an ability of the UE to decode the PDSCH transmission. In some aspects, the method may further include transmitting downlink control information (DCI) associated with the PDSCH transmission, where the DCI indicates a first modulation coding scheme (MCS) value associated with the PDSCH transmission. In some aspects, receiving either the ACK transmission or the NACK transmission from the UE in response to the transmission of the PDSCH transmission may include receiving either the ACK transmission or the NACK transmission from the UE based on a threshold difference between the first MCS value and a second measured MCS value associated with the PDSCH transmission. 
     In some aspects, the method may further include receiving the SB-CSI report from the UE when the ACK transmission is received from the UE, and receiving the SB-CSI report from the UE when the NACK transmission is received from the UE. In some aspects, the method may further include receiving the SB-CSI report from the UE when the NACK transmission is received from the UE, or determining that the SB-CSI report is not received from the UE when the ACK transmission is received from the UE. In some aspects, when receiving the SB-CSI report from the UE, at least one of the ACK transmission or the NACK transmission may include an indication that the SB-CSI report is to be received from the UE. In some aspects, the SB-CSI report may include one of SB reporting with full resolution, where the SB reporting with full resolution indicates one or more channel quality information (CQI) values each associated with a sub-band of a plurality of sub-bands utilized by the PDSCH transmission or SB reporting without full resolution, where the SB reporting without full resolution indicates one or more spatial differential CQI values each associated with an offset level, and where the offset level comprises a difference between a CQI value associated with a sub-band of the plurality of sub-bands utilized by the PDSCH transmission and an average CQI value associated with the plurality of sub-bands utilized by the PDSCH transmission. In some aspects, the one or more CQI values may include at least one of a CQI index, a modulation scheme, a code rate, or an efficiency. 
     In some aspects, the SB-CSI report may include either the SB reporting with full resolution or the SB reporting without full resolution based on at least a quality of a decoding of the PDSCH transmission by the UE. In some aspects, the method may include transmitting a control message to the UE indicating whether the UE is to transmit the SB-CSI report with the SB reporting with full resolution or the SB reporting without full resolution. In some aspects, receiving the SB-CSI report with the SB reporting with full resolution or the SB-CSI report with the SB reporting without full resolution is based on at least the control message. In some aspects, the control message may include at least one of a radio resource control (RRC) message, a medium access control (MAC) control element (MAC-CE), or a downlink control information (DCI). 
     In some aspects, the SB reporting with full resolution may include a rank indication per sub-band indicating a quantity of sub-bands utilized by the PDSCH transmission that are able to be supported by the UE. In some aspects, when the SB reporting with full resolution includes the rank indication per sub-band, at least one of the ACK transmission or the NACK transmission may include an indication that the rank indication is to be included with the SB reporting with full resolution. In some aspects, the method may include transmitting downlink control information (DCI) associated with the PDSCH transmission, wherein the DCI includes a first modulation coding scheme (MCS) value associated with the PDSCH transmission. In some aspects, the SB reporting with full resolution may include the rank indication per sub-band based on a threshold difference between the first MCS value and a second measured MCS value associated with the PDSCH transmission. 
     A user equipment (UE) in a wireless communication system is provided. The UE includes a wireless transceiver. The UE also includes a memory. The UE further includes a processor communicatively coupled to the wireless transceiver and the memory. The processor and the memory are configured to receive a physical downlink shared channel (PDSCH) transmission from a base station. The processor and the memory are also configured to transmit either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission to the base station in response to a reception of the PDSCH transmission. The processor and the memory are further configured to determine whether to transmit a sub-band (SB) channel state information (SB-CSI) report to the base station based on whether the ACK transmission is transmitted to the base station or whether the NACK transmission is transmitted to the base station. 
     A base station in a wireless communication system is provided. The base station includes a wireless transceiver. The base station also includes a memory. The base station further includes a processor communicatively coupled to the wireless transceiver and the memory. The processor and the memory are configured to transmit a physical downlink shared channel (PDSCH) transmission to a user equipment (UE). The processor and the memory are also configured to receive either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission from the UE in response to the transmission of the PDSCH transmission. The processor and the memory are further configured to receive a sub-band (SB) channel state information (SB-CSI) report from the UE based on whether the ACK transmission is transmitted by the UE or the NACK transmission is transmitted by the UE. 
     A non-transitory, processor-readable storage medium of a user equipment (UE) having instructions stored thereon is provided. The instructions, when executed by a processing circuit, cause the processing circuit to receive a physical downlink shared channel (PDSCH) transmission from a base station. The instructions, when executed by the processing circuit, also cause the processing circuit to transmit either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission to the base station in response to a reception of the PDSCH transmission. The instructions, when executed by the processing circuit, further cause the processing circuit to determine whether to transmit a sub-band (SB) channel state information (SB-CSI) report to the base station based on whether the ACK transmission is transmitted to the base station or whether the NACK transmission is transmitted to the base station. 
     A non-transitory, processor-readable storage medium of a base station having instructions stored thereon is provided. The instructions, when executed by a processing circuit, cause the processing circuit to transmit a physical downlink shared channel (PDSCH) transmission to a user equipment (UE). The instructions, when executed by the processing circuit, also cause the processing circuit to receive either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission from the UE in response to the transmission of the PDSCH transmission. The instructions, when executed by the processing circuit, further cause the processing circuit to receive a sub-band (SB) channel state information (SB-CSI) report from the UE based on whether the ACK transmission is transmitted by the UE or the NACK transmission is transmitted by the UE. 
     A user equipment (UE) is provided. The UE includes a means for receiving a physical downlink shared channel (PDSCH) transmission from a base station. The UE also includes a means for transmitting either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission to the base station in response to a reception of the PDSCH transmission. The UE further includes a means for determining whether to transmit a sub-band (SB) channel state information (SB-CSI) report to the base station based on whether the ACK transmission is transmitted to the base station or whether the NACK transmission is transmitted to the base station. 
     A base station is provided. The base station includes a means for transmitting a physical downlink shared channel (PDSCH) transmission to a user equipment (UE). The base station also includes a means for receiving either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission from the UE in response to the transmission of the PDSCH transmission. The base station further includes a means for receiving a sub-band (SB) channel state information (SB-CSI) report from the UE based on whether the ACK transmission is transmitted by the UE or the NACK transmission is transmitted by the UE. 
     These and other aspects of the invention will become more fully understood upon a review of the detailed description, which follows. Other aspects, features, and embodiments will become apparent to those of ordinary skill in the art, upon reviewing the following description of specific, exemplary embodiments in conjunction with the accompanying figures. While features may be discussed relative to certain embodiments and figures below, all embodiments can include one or more of the advantageous features discussed herein. In other words, while one or more embodiments may be discussed as having certain advantageous features, one or more of such features may also be used in accordance with the various embodiments discussed herein. In similar fashion, while exemplary embodiments may be discussed below as device, system, or method embodiments it should be understood that such exemplary embodiments can be implemented in various devices, systems, and methods. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic illustration of a wireless communication system according to some aspects. 
         FIG. 2  is a conceptual illustration of an example of a radio access network according to some aspects. 
         FIG. 3  is a block diagram illustrating a wireless communication system supporting multiple-input multiple-output (MIMO) communication according to some aspects. 
         FIG. 4  is a diagram illustrating an example of communication between a base station and a UE using beamforming according to some aspects. 
         FIG. 5  is a schematic illustration of an organization of wireless resources in an air interface utilizing orthogonal frequency divisional multiplexing (OFDM) according to some aspects. 
         FIG. 6  is a schematic illustration of an OFDM air interface utilizing a scalable numerology according to some aspects. 
         FIG. 7  is a conceptual signaling diagram illustrating an exemplary procedure for reporting sub-band (SB) channel state information (SB-CSI) according to some aspects. 
         FIG. 8  is an illustration of a 4-bit channel quality indicator (CQI) table according to some aspects. 
         FIG. 9  is an illustrating of a table mapping spatial differential CQI values to offset level according to some aspects. 
         FIG. 10  is an illustration of a first example table correlating bits values with acknowledgement (ACK) transmission and negative acknowledgement (NACK) transmission types according to some aspects. 
         FIG. 11  is an illustration of a second example table correlating bits values with acknowledgement (ACK) transmission and negative acknowledgement (NACK) transmission types according to some aspects. 
         FIG. 12  is an illustration of a third example table correlating bits values with acknowledgement (ACK) transmission and negative acknowledgement (NACK) transmission types according to some aspects. 
         FIG. 13A  is an illustration of a fourth example table correlating bits values with acknowledgement (ACK) transmission and negative acknowledgement (NACK) transmission types according to some aspects. 
         FIG. 13B  is an illustration of a fifth example table correlating bit value with transmission types according to some aspects. 
         FIG. 14  is a block diagram conceptually illustrating an example of a hardware implementation for a user equipment (UE) according to some aspects. 
         FIG. 15  is a flow chart of a first example method for reporting SB-CSI according to some aspects. 
         FIG. 16  is a flow chart of a second example method for reporting SB-CSI according to some aspects. 
         FIG. 17  is a flow chart of a third example method for reporting SB-CSI according to some aspects. 
         FIG. 18  is a flow chart of a fourth example method for reporting SB-CSI according to some aspects. 
         FIG. 19  is a flow chart of a fifth example method for reporting SB-CSI according to some aspects. 
         FIG. 20  is a flow chart of a sixth example method for reporting SB-CSI according to some aspects. 
         FIG. 21  is a flow chart of a seventh example method for reporting SB-CSI according to some aspects. 
         FIG. 22  is a flow chart of an eighth example method for reporting SB-CSI according to some aspects. 
         FIG. 23  is a flow chart of a ninth example method for reporting SB-CSI according to some aspects. 
         FIG. 24  is a flow chart of a tenth example method for reporting SB-CSI according to some aspects. 
         FIG. 25  is a flow chart of an eleventh example method for reporting SB-CSI according to some aspects. 
         FIG. 26  is a flow chart of a twelfth example method for reporting SB-CSI according to some aspects. 
         FIG. 27  is a block diagram conceptually illustrating an example of a hardware implementation for a base station according to some aspects. 
         FIG. 28  is a flow chart of a thirteenth example method for reporting SB-CSI according to some aspects. 
         FIG. 29  is a flow chart of a fourteenth example method for reporting SB-CSI according to some aspects. 
         FIG. 30  is a flow chart of a fifteenth example method for reporting SB-CSI according to some aspects. 
         FIG. 31  is a flow chart of a sixteenth example method for reporting SB-CSI according to some aspects. 
         FIG. 32  is a flow chart of a seventeenth example method for reporting SB-CSI according to some aspects. 
         FIG. 33  is a flow chart of an eighteenth example method for reporting SB-CSI according to some aspects. 
         FIG. 34  is a flow chart of a nineteenth example method for reporting SB-CSI according to some aspects. 
         FIG. 35  is a flow chart of a twentieth example method for reporting SB-CSI according to some aspects. 
         FIG. 36  is a flow chart of a twenty-first example method for reporting SB-CSI according to some aspects. 
         FIG. 37  is a flow chart of a twenty-second example method for reporting SB-CSI 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. 
     For ultra-reliable low latency communications (URLLCs) reliability is crucial. Generally, data is transmitted from a base station and delivered to a user equipment (UE) within two transmissions. The specified block error rate (BLER) for these data transmissions is 10 −5  which provides for a narrow margin particularly when interference exists. Interference is a challenge for enabling URLLC applications while maintaining a specified quality of service. 
     In some aspects, a user equipment (UE) may always transmit a report with differential channel quality information (CQI) of sub-bands with high resolution to a base station. In some cases, this may be referred to as a SB-CSI report with full resolution. A report with differential CQI of sub-bands with high resolution may include one or more CQI values each associated with a sub-band of a plurality of sub-bands utilized by a physical downlink shared channel (PDSCH) transmission. However, an SB-CSI report with full resolution can occupy a relatively large amount of payload and provide the base station with unnecessary information, for example, when the UE transmits an ACK transmission indicating relatively low interference or an ability of the UE to at least partially decode the PDSCH transmission. 
     In some aspects, a user equipment (UE) may transmit a report with one or more spatial differential CQI values each associated with an offset level, where the offset level includes a difference between a CQI value associated with a sub-band of the plurality of sub-bands utilized by the PDSCH transmission and an average CQI value associated with the plurality of sub-bands utilized by the PDSCH transmission. In some cases, this may be referred to as an SB-CSI report without full resolution. A UE may transmit to a base station an SB-CSI report without full resolution to a base station because such a report may occupy a relatively small amount of payload. However, such a report may not provide the base station with all the necessary information (e.g., relatively low resolution) to update a PDSCH transmission when the UE transmits a NACK transmission indicating relatively high interference or an inability of the UE to at least partially decode the PDSCH transmission. 
     While aspects and embodiments 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. Innovations described herein may be implemented across many differing platform types, devices, systems, shapes, sizes, and packaging arrangements. For example, embodiments and/or uses may come about via integrated chip embodiments 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 innovations may occur. Implementations may range a 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 innovations. 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 embodiments. 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 innovations 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, various aspects of the present disclosure are illustrated with reference to a wireless communication system  100 . The wireless communication system  100  includes three interacting domains: a core network  102 , a radio access network (RAN)  104 , and a user equipment (UE)  106 . By virtue of the wireless communication system  100 , the UE  106  may be enabled to carry out data communication with an external data network  110 , such as (but not limited to) the Internet. 
     The RAN  104  may implement any suitable wireless communication technology or technologies to provide radio access to the UE  106 . As one example, the RAN  104  may operate according to 3rd Generation Partnership Project (3GPP) New Radio (NR) specifications, often referred to as 5G. As another example, the RAN  104  may operate under a hybrid of 5G NR and Evolved Universal Terrestrial Radio Access Network (eUTRAN) standards, often referred to as Long-Term Evolution (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. 
     As illustrated, the RAN  104  includes a plurality of base stations  108  (e.g., a RAN entity, RAN node, or the like). Broadly, a base station is a network element in a radio access network responsible for radio transmission and reception in one or more cells to or from a UE. In different technologies, standards, or contexts, a base station may variously 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), aNode B (NB), an eNode B (eNB), a gNode B (gNB), a transmission and reception point (TRP), or some other suitable terminology. In some examples, a base station may include two or more TRPs that may be collocated or non-collocated. Each TRP may communicate on the same or different carrier frequency within the same or different frequency band. 
     The radio access network  104  is further illustrated supporting wireless communication for multiple mobile apparatuses. A mobile apparatus may be referred to as user equipment (UE) in 3GPP standards, 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. UEs may include a number of hardware structural components sized, shaped, and arranged to help in communication; such components can include antennas, antenna arrays, RF chains, amplifiers, one or more processors, etc. electrically coupled to each other. 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, 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, e.g., health care at a distance. Telehealth devices may include telehealth monitoring devices and telehealth administration devices, whose communication may be given preferential treatment or 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. 
     Wireless communication between a RAN  104  and a UE  106  may be described as utilizing an air interface. Transmissions over the air interface from a base station (e.g., base station  108 ) to one or more UEs (e.g., UE  106 ) 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  108 ). Another way to describe this scheme may be to use the term broadcast channel multiplexing. Transmissions from a UE (e.g., UE  106 ) to a base station (e.g., base station  108 ) 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  106 ). 
     In some examples, access to the air interface may be scheduled, wherein a scheduling entity (e.g., a base station  108 ) 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  106 , which may be scheduled entities, may utilize resources allocated by the scheduling entity  108 . 
     As illustrated in  FIG. 1 , a scheduling entity  108  may broadcast downlink traffic  112  to one or more scheduled entities  106 . Broadly, the scheduling entity  108  is a node or device responsible for scheduling traffic in a wireless communication network, including the downlink traffic  112  and, in some examples, uplink traffic  116  from one or more scheduled entities  106  to the scheduling entity  108 . On the other hand, the scheduled entity  106  is a node or device that receives downlink control information  114 , including but not limited to scheduling information (e.g., a grant), synchronization or timing information, or other control information from another entity in the wireless communication network such as the scheduling entity  108 . 
     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. 
     In general, base stations  108  may include a backhaul interface for communication with a backhaul portion  120  of the wireless communication system. The backhaul  120  may provide a link between a base station  108  and the core network  102 . Further, in some examples, a backhaul network may provide interconnection between the respective base stations  108 . 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 core network  102  may be a part of the wireless communication system  100 , and may be independent of the radio access technology used in the RAN  104 . In some examples, the core network  102  may be configured according to 5G standards (e.g., 5GC). In other examples, the core network  102  may be configured according to a 4G evolved packet core (EPC), or any other suitable standard or configuration. 
     Referring now to  FIG. 2 , by way of example and without limitation, a schematic illustration of a RAN  200  is provided. In some examples, the RAN  200  may be the same as the RAN  104  described above and illustrated in  FIG. 1 . The geographic area covered by the RAN  200  may be divided into cellular regions (cells) that can be uniquely identified by a user equipment (UE) based on an identification broadcasted from one access point or base station.  FIG. 2  illustrates macrocells  202 ,  204 , and  206 , and a small cell  208 , 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. 
     Various base station arrangements can be utilized. For example, in  FIG. 2 , two base stations  210  and  212  are shown in cells  202  and  204 ; and a third base station  214  is shown controlling a remote radio head (RRH)  216  in cell  206 . 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  202 ,  204 , and  206  may be referred to as macrocells, as the base stations  210 ,  212 , and  214  support cells having a large size. Further, a base station  218  is shown in the small cell  208  (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  208  may be referred to as a small cell, as the base station  218  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  200  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  210 ,  212 ,  214 ,  218  provide wireless access points to a core network for any number of mobile apparatuses. In some examples, the base stations  210 ,  212 ,  214 , and/or  218  may be the same as the base station/scheduling entity  108  described above and illustrated in  FIG. 1 . 
     Within the RAN  200 , the cells may include UEs that may be in communication with one or more sectors of each cell. Further, each base station  210 ,  212 ,  214 , and  218  may be configured to provide an access point to a core network (e.g., as illustrated in  FIGS. 1 and/or 2 ) for all the UEs in the respective cells. For example, UEs  222  and  224  may be in communication with base station  210 ; UEs  226  and  228  may be in communication with base station  412 ; UEs  230  and  232  may be in communication with base station  214  by way of RRH  216 ; and UE  234  may be in communication with base station  218 . In some examples, the UEs  222 ,  224 ,  226 ,  228 ,  230 ,  232 ,  234 ,  238 ,  240 , and/or  242  may be the same as the UE/scheduled entity  106  described above and illustrated in  FIG. 1 . 
     In some examples, an unmanned aerial vehicle (UAV)  220 , which may be a drone or quadcopter, can be a mobile network node and may be configured to function as a UE. For example, the UAV  220  may operate within cell  202  by communicating with base station  210 . 
     Base stations  210 ,  212 ,  214 ,  218  may operate as scheduling entities, scheduling resources for communication among the UEs within their service areas or cells  202 ,  204 ,  206 ,  208 , respectively. However, base stations are not the only entities that may function as a scheduling entity. 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). For example, two or more UEs (e.g., UEs  238 ,  240 , and  242 ) may communicate with each other using peer to peer (P2P) or sidelink signals  237  without relaying that communication through a base station. In some examples, the UEs  238 ,  240 , and  242  may each function as a scheduling entity or transmitting sidelink device and/or a scheduled entity or a receiving sidelink device to schedule resources and communicate sidelink signals  237  therebetween without relying on scheduling or control information from a base station. In other examples, two or more UEs (e.g., UEs  226  and  228 ) within the coverage area of a base station (e.g., base station  212 ) may also communicate sidelink signals  227  over a direct link (sidelink) without conveying that communication through the base station  246 . In this example, the base station  212  may allocate resources to the UEs  226  and  228  for the sidelink communication. In either case, such sidelink signaling  227  and  237  may be implemented in a P2P network, a device-to-device (D2D) network, vehicle-to-vehicle (V2V) network, a vehicle-to-everything (V2X), a mesh network, or other suitable direct link network. 
     In the RAN  200 , the ability for a UE to communicate while moving, independent of its location, is referred to as mobility. The various physical channels between the UE and the radio access network are generally set up, maintained, and released under the control of an AMF. 
     A RAN  200  may utilize DL-based mobility or UL-based mobility to enable mobility and handovers (e.g., the transfer of a UE&#39;s connection from one radio channel to another). In a network configured for DL-based mobility, 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  224  (illustrated as a vehicle, although any suitable form of UE may be used) may move from the geographic area corresponding to its serving cell  202  to the geographic area corresponding to a neighbor cell  206 . When the signal strength or quality from the neighbor cell  206  exceeds that of its serving cell  202  for a given amount of time, the UE  224  may transmit a reporting message to its serving base station  210  indicating this condition. In response, the UE  224  may receive a handover command, and the UE may undergo a handover to the cell  206 . 
     In a network configured for UL-based mobility, UL reference signals from each UE may be utilized by the network to select a serving cell for each UE. In some examples, the base stations  210 ,  212 , and  214 / 216  may broadcast unified synchronization signals (e.g., unified Primary Synchronization Signals (PSSs), unified Secondary Synchronization Signals (SSSs) and unified Physical Broadcast Channels (PBCH)). The UEs  222 ,  224 ,  226 ,  228 ,  230 , and  232  may receive the unified synchronization signals, derive the carrier frequency and slot timing from the synchronization signals, and in response to deriving timing, transmit an uplink pilot or reference signal. The uplink pilot signal transmitted by a UE (e.g., UE  224 ) may be concurrently received by two or more cells (e.g., base stations  210  and  214 / 216 ) within the radio access network  200 . Each of the cells may measure a strength of the pilot signal, and the radio access network (e.g., one or more of the base stations  210  and  214 / 216  and/or a central node within the core network) may determine a serving cell for the UE  224 . As the UE  224  moves through the radio access network  200 , the network may continue to monitor the uplink pilot signal transmitted by the UE  224 . When the signal strength or quality of the pilot signal measured by a neighboring cell exceeds that of the signal strength or quality measured by the serving cell, the network  200  may handover the UE  224  from the serving cell to the neighboring cell, with or without informing the UE  224 . 
     Although the synchronization signal transmitted by the base stations  210 ,  212 , and  214 / 216  may be unified, the synchronization signal may not identify a particular cell, but rather may identify a zone of multiple cells operating on the same frequency and/or with the same timing. The use of zones in 5G networks or other next generation communication networks enables the uplink-based mobility framework and improves the efficiency of both the UE and the network, since the number of mobility messages that need to be exchanged between the UE and the network may be reduced. 
     In various implementations, the air interface in the radio access network  200  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. 
     The air interface in the radio access network  200  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 transmissions from UEs  222  and  224  to base station  210 , and for multiplexing for DL transmissions from base station  210  to one or more UEs  222  and  224 , 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  210  to UEs  222  and  224  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. 
     The air interface in the radio access network  200  may further 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 some aspects of the disclosure, the scheduling entity and/or scheduled entity may be configured for beamforming and/or multiple-input multiple-output (MIMO) technology.  FIG. 3  illustrates an example of a wireless communication system  300  supporting 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  108 , a scheduled entity  106 , 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 (e.g., 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 Time Division Duplex (TDD) systems, the UL and DL are reciprocal, in that each uses different time slots of the same frequency bandwidth. Therefore, in TDD systems, the base station may assign the rank for DL MIMO transmissions based on UL SINR measurements (e.g., based on a Sounding Reference Signal (SRS) transmitted from the UE or other pilot signal). Based on the assigned rank, the base station may then transmit the CSI-RS with separate C-RS sequences for each layer to provide for multi-layer channel estimation. From the CSI-RS, the UE may measure the channel quality across layers and resource blocks and feed back the CQI and RI values to the base station for use in updating the rank and assigning REs for future downlink transmissions. 
     In the simplest case, 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 . A beam may be formed by, but not limited to, an antenna, an antenna port, an antenna element, a group of antennas, a group of antenna ports or a group of antenna elements. The beam may be alternatively made with a certain reference signal resource. The beam may be equivalent to a spatial domain filtering by which an electromagnetic (EM) radiation is transmitted. 
     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). 
       FIG. 4  is a diagram illustrating communication between a base station  404  and a UE  402  using beamformed signals according to some aspects. The base station  404  may be any of the base stations (e.g., gNBs) or scheduling entities illustrated in  FIGS. 1-3 , and the UE  402  may be any of the UEs or scheduled entities illustrated in  FIGS. 1-3 . 
     The base station  404  may generally be capable of communicating with the UE  402  using one or more transmit beams, and the UE  402  may further be capable of communicating with the base station  404  using one or more receive beams. As used herein, the term transmit beam refers to a beam on the base station  404  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  404 . 
     In the example shown in  FIG. 4 , the base station  404  is configured to generate a plurality of transmit beams  406   a ,  406   b ,  406   c ,  406   d ,  406   e ,  406   f ,  406   g , and  406   h  ( 406   a - 406   h ), each associated with a different spatial direction. In addition, the UE  402  is configured to generate a plurality of receive beams  408   a ,  408   b ,  408   c ,  408   d , and  408   e  ( 408   a - 408   e ), each associated with a different spatial direction. It should be noted that while some beams are illustrated as adjacent to one another, such an arrangement may be different in different aspects. For example, transmit beams  406   a - 406   h  transmitted during a same symbol may not be adjacent to one another. In some examples, the base station  404  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   h  may include beams of varying beam width. For example, the base station  404  may transmit certain signals (e.g., synchronization signal blocks (SSBs)) on wider beams and other signals (e.g., CSI-RSs) on narrower beams. 
     The base station  404  and UE  402  may select one or more transmit beams  406   a - 406   h  on the base station  404  and one or more receive beams  408   a - 408   e  on the UE  402  for communication of uplink and downlink signals therebetween using a beam management procedure. In one example, during initial cell acquisition, the UE  402  may perform a P1 beam management procedure to scan the plurality of transmit beams  406   a - 406   h  on the plurality of receive beams  408   a - 408   e  to select a beam pair link (e.g., one of the transmit beams  406   a - 406   h  and one of the receive beams  408   a - 408   e ) for a physical random access channel (PRACH) procedure for initial access to the cell. For example, periodic SSB beam sweeping may be implemented on the base station  404  at certain intervals (e.g., based on the SSB periodicity). Thus, the base station  404  may be configured to sweep or transmit an SSB on each of a plurality of wider transmit beams  406   a - 406   h  during the beam sweeping interval. The UE 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 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  404  and UE  402  may perform a P2 beam management procedure for beam refinement at the base station  404 . For example, the base station  404  may be configured to sweep or transmit a CSI-RS on each of a plurality of narrower transmit beams  406   a - 406   h . 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  on the plurality of receive beams  408   a - 408   e . The UE  402  then performs beam measurements (e.g., RSRP, SINR, etc.) of the received CSI-RSs on each of the receive beams  408   a - 408   e  to determine the respective beam quality of each of the CSI-RS transmit beams  406   a - 406   h  as measured on each of the receive beams  408   a - 408   e.    
     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  on one or more of the receive beams  408   a - 408   e  to the base station  404 . The base station  404  may then select one or more CSI-RS transmit beams 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 some examples, in addition to performing CSI-RS beam measurements, the base station  404  may configure the UE  402  to perform SSB beam measurements and provide an L1 measurement report containing beam measurements of SSB transmit beams  406   a - 406   h . For example, the base station  404  may configure the UE  402  to perform SSB beam measurements and/or CSI-RS beam measurements for beam failure detection (BRD), beam failure recovery (BFR), cell reselection, beam tracking (e.g., for a mobile UE  402  and/or base station  404 ), or other beam optimization purpose. 
     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   e . For example, the UE  402  may transmit an SRS on each beam in the different beam directions. In addition, the base station  404  may be configured to receive the uplink beam reference signals on a plurality of transmit beams  406   a - 406   h . The base station  404  then performs beam measurements (e.g., RSRP, SINR, etc.) of the beam reference signals on each of the transmit beams  406   a - 406   h  to determine the respective beam quality of each of the receive beams  408   a - 408   e  as measured on each of the transmit beams  406   a - 406   h.    
     The base station  404  may then select one or more transmit beams 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 CSI-RS transmit beam (e.g., beam  406   d ) on the base station  404  and a single receive beam (e.g., beam  408   c ) on the UE may form a single BPL used for communication between the base station  404  and the UE  402 . In another example, multiple CSI-RS transmit beams (e.g., beams  406   c ,  406   d , and  406   e ) on the base station  404  and a single receive beam (e.g., beam  408   c ) on the UE  402  may form respective BPLs used for communication between the base station  404  and the UE  402 . In another example, multiple CSI-RS transmit beams (e.g., beams  406   c ,  406   d , and  406   e ) on the base station  404  and multiple receive beams (e.g., beams  408   c  and  408   d ) on the UE  402  may form multiple BPLs used for communication between the base station  404  and the UE  402 . In this example, a first BPL may include transmit beam  406   c  and receive beam  408   c , a second BPL may include transmit beam  408   d  and receive beam  408   c , and a third BPL may include transmit beam  408   e  and receive beam  408   d.    
     Various aspects of the present disclosure will be described with reference to an OFDM waveform, schematically illustrated in  FIG. 5 . 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. 5 , an expanded view of an exemplary DL subframe  502  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  504  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  504  may be available for communication. The resource grid  504  is divided into multiple resource elements (REs)  506 . 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)  508 , 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  508  entirely corresponds to a single direction of communication (either transmission or reception for a given device). 
     Scheduling of UEs (e.g., scheduled entities) for downlink or uplink transmissions typically involves scheduling one or more resource elements  506  within one or more sub-bands. Thus, a UE generally utilizes only a subset of the resource grid  504 . 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. 
     In this illustration, the RB  508  is shown as occupying less than the entire bandwidth of the subframe  502 , with some subcarriers illustrated above and below the RB  508 . In a given implementation, the subframe  502  may have a bandwidth corresponding to any number of one or more RBs  508 . Further, in this illustration, the RB  508  is shown as occupying less than the entire duration of the subframe  502 , although this is merely one possible example. 
     Each 1 ms subframe  502  may consist of one or multiple adjacent slots. In the example shown in  FIG. 5 , one subframe  502  includes four slots  510 , 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  510  illustrates the slot  510  including a control region  512  and a data region  514 . In general, the control region  512  may carry control channels, and the data region  514  may carry 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. 5  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. 5 , the various REs  506  within a RB  508  may be scheduled to carry one or more physical channels, including control channels, shared channels, data channels, etc. Other REs  506  within the RB  508  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  508 . 
     In some examples, the slot  510  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  506  (e.g., within the control region  512 ) 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, where 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  506  (e.g., in the control region  512  or the data region  514 ) 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 140 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 CORESET0), 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  506  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, including pilots, reference signals, and information configured to enable or assist in decoding uplink data transmissions. Examples of uplink reference signals may include a sounding reference signal (SRS) and an uplink DMRS. In some examples, the UCI may include a scheduling request (SR), e.g., 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. 
     In addition to control information, one or more REs  506  (e.g., within the data region  514 ) 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  506  within the data region  514  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 proximity service (ProSe) PC5 interface, the control region  512  of the slot  510  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  514  of the slot  510  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  506  within slot  510 . For example, HARQ feedback information may be transmitted in a physical sidelink feedback channel (PSFCH) within the slot  510  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  510 . 
     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 herein 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. 
     In OFDM, to maintain orthogonality of the subcarriers or tones, the subcarrier spacing may be equal to the inverse of the symbol period. A numerology of an OFDM waveform refers to its particular subcarrier spacing and cyclic prefix (CP) overhead. A scalable numerology refers to the capability of the network to select different subcarrier spacings, and accordingly, with each spacing, to select the corresponding symbol duration, including the CP length. With a scalable numerology, a nominal subcarrier spacing (SCS) may be scaled upward or downward by integer multiples. In this manner, regardless of CP overhead and the selected SCS, symbol boundaries may be aligned at certain common multiples of symbols (e.g., aligned at the boundaries of each 1 ms subframe). The range of SCS may include any suitable SCS. For example, a scalable numerology may support a SCS ranging from 15 kHz to 480 kHz. 
     To illustrate this concept of a scalable numerology,  FIG. 6  shows a first RB  602  having a nominal numerology, and a second RB  604  having a scaled numerology. As one example, the first RB  602  may have a ‘nominal’ subcarrier spacing (SCS n ) of 30 kHz, and a ‘nominal’ symbol duration n  of 333 ρs. Here, in the second RB  604 , the scaled numerology includes a scaled SCS of double the nominal SCS, or 2×SCS n =60 kHz. Because this provides twice the bandwidth per symbol, it results in a shortened symbol duration to carry the same information. Thus, in the second RB  604 , the scaled numerology includes a scaled symbol duration of half the nominal symbol duration, or (symbol duration n )÷2=167 μs. 
     For ultra-reliable low latency communications (URLLCs) reliability is crucial. Generally, data is transmitted from a base station and delivered to a user equipment (UE) within two transmissions. The specified block error rate (BLER) for these data transmissions is 10 −5  which provides for a narrow margin particularly when interference exists. Interference is a challenge for enabling URLLC applications while maintaining a specified quality of service. 
     In some aspects, a user equipment (UE) may always transmit a report with differential channel quality information (CQI) of sub-bands with high resolution to a base station. In some cases, this may be referred to as a SB-CSI report with full resolution. A report with differential CQI of sub-bands with high resolution may include one or more CQI values each associated with a sub-band of a plurality of sub-bands utilized by a physical downlink shared channel (PDSCH) transmission. However, an SB-CSI report with full resolution can occupy a relatively large amount of payload and provide the base station with unnecessary information, for example, when the UE transmits an ACK transmission indicating relatively low interference or an ability of the UE to at least partially decode the PDSCH transmission. 
     In some aspects, a user equipment (UE) may transmit a report with one or more spatial differential CQI values each associated with an offset level, where the offset level includes a difference between a CQI value associated with a sub-band of the plurality of sub-bands utilized by the PDSCH transmission and an average CQI value associated with the plurality of sub-bands utilized by the PDSCH transmission. In some cases, this may be referred to as an SB-CSI report without full resolution. A UE may transmit to a base station an SB-CSI report without full resolution to a base station because such a report may occupy a relatively small amount of payload. However, such a report may not provide the base station with all the necessary information (e.g., relatively low resolution) to update a PDSCH transmission when the UE transmits a NACK transmission indicating relatively high interference or an inability of the UE to at least partially decode the PDSCH transmission. 
       FIG. 7  is a conceptual signaling diagram  700  illustrating an exemplary procedure for reporting sub-band (SB) channel state information (SB-CSI) according to some aspects. In the example shown in  FIG. 7 , a user equipment (UE)  702  is in wireless communication with a base station  704  over one or more wireless communication links. Each of the UE  702  and the base station  704  may correspond to any of the entities, gNodeBs, UEs, or the like as shown in  FIGS. 1-4 . 
     At  706 , the UE  702  may receive a physical downlink shared channel (PDSCH) transmission from the base station  704 . At  708 , the UE  702  may transmit either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission to the base station in response to a reception of the PDSCH transmission. For example, the UE  702  may receive the PDSCH transmission from the base station  704  and attempt to decode the PDSCH transmission. Based on an ability of the UE  702  to decode the PDSCH transmission, the UE  702  may transmit either an ACK transmission or a NACK transmission. In some aspects, when the UE  702  is unable to decode the PDSCH transmission, the UE  702  may transmit a NACK transmission to the base station  704  and when the UE  702  is able to decode the PDSCH transmission, the UE  702  may transmit an ACK transmission. 
     In some aspects, before receiving the PDSCH transmission from the base station  704 , the UE  702  may receive downlink control information (DCI) associated with the PDSCH transmission. The DCI may indicate a first modulation coding scheme (MCS) value associated with the PDSCH transmission. The UE  702  may also configure the reception of the DCI for receiving the PDSCH transmission. Subsequently, the UE  702  may receive the PDSCH transmission from the base station  704  and measure a second MCS value associated with the received PDSCH transmission. The UE  702  may transmit either the ACK transmission or the NACK transmission to the base station in response to receiving the PDSCH transmission and based on a threshold difference between the first MCS value and the second MCS value. For example, when the difference between the first MCS value and the second MCS value is greater than the threshold difference, the UE  702  may transmit the NACK transmission. However, when the difference between the first MCS value and the second MCS value is no greater than the threshold difference, the UE  702  may transmit the ACK transmission. 
     At  710 , the UE  702  may determine whether to transmit a sub-band (SB) channel state information (SB-CSI) report to the base station  704  based on whether the ACK transmission is transmitted to the base station  704  or whether the NACK transmission is transmitted to the base station  704 . In some aspects, the UE  702  may determine to transmit an SB-CSI report to the base station  704  when a NACK transmission is transmitted to the base station  704  and may determine to abstain from transmitting an SB-CSI report to the base station  704  when an ACK transmission is transmitted to the base station  704 . In some examples, the UE  702  may determine to transmit a CSI configured report to the base station  704 , as described herein, when a NACK transmission is transmitted to the base station  704 . Additionally, or alternatively, the UE  702  may determine not to transmit a CSI configured report to the base station  704  when an ACK transmission is transmitted to the base station  704 . In some aspects, the UE  702  may determine to transmit an SB-CSI report or a CSI configured report to the base station  704  when a NACK transmission is transmitted to the base station and/or when an ACK transmission is transmitted to the base station  704 . For example, the UE  702  may determine to transmit an SB-CSI report or a CSI configured report to the base station  704  regardless of whether an ACK transmission or a NACK transmission is transmitted to the base station  704 . 
     At  712 , the UE  702  may transmit the SB-CSI report to the base station  704  based on whether the ACK transmission is transmitted to the base station  704  or whether the NACK transmission is transmitted to the base station  704 . In some aspects, the UE  702  may transmit an SB-CSI report to the base station  704  when a NACK transmission is transmitted to the base station  704  and may abstain from transmitting an SB-CSI report to the base station  704  when an ACK transmission is transmitted to the base station  704 . In some examples, the UE  702  may transmit a CSI configured report to the base station  704 , as described herein, when a NACK transmission is transmitted to the base station  704 . Additionally, or alternatively, the UE  702  may not transmit a CSI configured report to the base station  704  when an ACK transmission is transmitted to the base station  704 . In some aspects, the UE  702  may transmit an SB-CSI report or a CSI configured report to the base station  704  when a NACK transmission is transmitted to the base station and/or when an ACK transmission is transmitted to the base station  704 . For example, the UE  702  may transmit an SB-CSI report or a CSI configured report to the base station  704  regardless of whether an ACK transmission or a NACK transmission is transmitted to the base station  704 . 
     In some aspects, when the UE  702  determines to transmit the SB-CSI report to the base station, the UE  702  may also include, with the SB-CSI report, SB reporting with full resolution, where the SB-CSI report with full resolution indicates one or more channel quality information (CQI) values each associated with a sub-band of a plurality of sub-bands utilized by the PDSCH transmission or SB reporting without full resolution, where the SB reporting without full resolution indicates one or more spatial differential CQI values each associated with an offset level, and where the offset level includes a difference between a CQI value associated with a sub-band of the plurality of sub-bands utilized by the PDSCH transmission and an average CQI value associated with the plurality of sub-bands utilized by the PDSCH transmission. In some examples, the one or more CQI values may include at least one of a CQI index, a modulation scheme, a code rate, or an efficiency. In some examples, the UE  702  determining whether to transmit to the base station  704  the SB-CSI report including the SB reporting with full resolution or transmit the SB-CSI report including the SB reporting without full resolution having one or more spatial differential CQI values each associated with an offset level may be based on at least a quality of a decoding of the PDSCH transmission. 
       FIG. 8  is an illustration of a table  800  of 4-bit channel quality indicators (CQI) according to some aspects. The table  800  may be an example of SB reporting with full resolution that may be included with an SB-CSI report. As shown in  FIG. 8 , the table  800  includes a column of CQI indices  802 , a column of modulations  804 , a column of code rates  806 , and a column of efficiencies  808 . Each modulation, code rate, and efficiency in a particular row aligns with a CQI index sharing that same particular row. Each of the CQI indexes may be indicative of a particular sub-band. Generally, the SB reporting with full resolution provides better resolution than SB reporting without full resolution but also occupies a greater payload during transmission, for example, on a physical uplink control channel (PUCCH). Because of this, the UE  702  may determine to include, with the transmission of the SB-CSI report, the SB reporting with full resolution when there is a bad signal or decoding of the PDSCH transmission fails in order to provide the base station  704  with the resolution needed to remedy the bad signal or the failed decoding. 
       FIG. 9  is an illustrating of a table  900  mapping spatial differential CQI values to offset level according to some aspects. The table  900  may be an example of SB reporting without full resolution that may be included with an SB-CSI report. The table  900  maps spatial differential CQI values to offset levels. As shown in  FIG. 9 , the table  900  includes a column of spatial differential CQI values  902  and a column of offset levels  904 . Each offset level in a particular row aligns with a spatial differential CQI index value sharing that same particular row. Generally, the SB reporting without full resolution does not provide the same amount of resolution that the SB reporting with full resolution provides. However, the SB reporting without full resolution also occupies a lesser payload than the SB reporting with full resolution during transmission, for example, on a physical uplink control channel (PUCCH). Because of this, the UE  702  may determine to transmit the SB-CSI report including the SB reporting without full resolution to the base station  704  when a signal is above a threshold or decoding of the PDSCH transmission is at least partially successful in order to provide the base station  704  with some resolution at a reduced transmission payload. 
     In some aspects, the UE  702  may determine not to transmit an SB-CSI report to the base station  704 . For example, instead of transmitting an SB-CSI report to the base station  704 , the UE  702  may transmit a CSI configured report. A CSI configured report may include wideband (WB) reporting of CQI values and one or more WB rank indications (e.g., ranking a quantity or number of layers). In some aspects, a CSI configured report may include SB reporting without full resolution and also one or more WB rank indications. 
     In some examples, before the UE  702  determines whether to transmit the SB-CSI report, the UE  702  may receive from the base station  704  a control message indicating whether the UE  702  is to transmit the SB-CSI report including the SB reporting with full resolution to the base station, or whether the UE  702  is to transmit the SB-CSI report including SB reporting without full resolution. The UE  702  may receive the control message and determine whether to transmit the SB-CSI report including the SB reporting with full resolution to the base station or the SB-CSI report with the SB reporting without full resolution based at least on the control message. In some aspects, the UE  702  may receive the control message and determine to transmit a CSI configured report instead of an SB-CSI report based at least on the control message. The control message may include at least one of a radio resource control (RRC) message, a medium access control (MAC) control element (MAC-CE), or a downlink control information (DCI). 
     In some examples, the UE may include a rank indication (RI) with an SB-CSI report. An RI may be on a per sub-band basis and indicate a rank of a particular sub-band amongst a plurality of sub-bands. For example, in response to determining that a NACK transmission is transmitted to the base station  704 , the UE  702  may determine to include an RI with the SB-CSI report for transmission to the base station  704 . In some aspects, the RI may indicate to the base station  704  a quantity of sub-bands utilized by the PDSCH transmission that are able to be supported by the UE  702 . 
     In some aspects, the base station  704  transmit to the UE  702  a table through RRC signal or a medium access control (MAC) control element (MAC-CE) to correlate bit values with types of SB-CSI report transmissions. The UE  702  may also provide an indication (e.g., one or more bit values) based on the table in an ACK transmission or a NACK transmission to the base station  704  and in response to receiving the PDSCH transmission so that the base station  704  expects to receive a particular type of SB-CSI report from the UE  702 . 
       FIGS. 10, 11, 12, 13A, and 13B  are illustrations of tables correlating bits values with acknowledgement (ACK) transmission and negative acknowledgement (NACK) transmission types according to some aspects. As shown in  FIG. 10 , table  1000  includes a column with bit value  1002 , and in this case, three bit values “00”, “01”, and “10”. The table  1000  correlates each bit value with a representation of a SB-CSI report type  1004 . For example, the bit value “00” correlates with a NACK transmission and a CSI configured report. As another example, the bit value “01” correlates with a NACK transmission and an SB-CSI report with full resolution. As yet another example, the bit value “10” correlates with an ACK transmission. Thus, based on the table  1000  received from the base station  704 , the UE  702  may transmit a bit value to the base station  704  indicating a NACK or an ACK and whether the base station  704  should expect to receive a CSI configured report or an SB-CSI report with full resolution. 
     As shown in  FIG. 11 , table  1100  includes a column with bit value  1102 , and in this case, four bit values “00”, “01”, “10”, and “11.” The table  1100  correlates each bit value with a representation of a SB-CSI report type  1104 . For example, the bit value “00” correlates with a NACK transmission and a CSI configured report. As another example, the bit value “01” correlates with a NACK transmission and an SB-CSI report with full resolution. As yet another example, the bit value “10” correlates with an ACK transmission and a CSI configured report. As another example, the bit value “11” correlates with an ACK transmission and an SB-CSI report with full resolution. Thus, based on the table  1200  received from the base station  704 , the UE  702  may transmit a bit value to the base station  704  indicating a NACK or an ACK and whether the base station  704  should expect to receive a CSI configured report or an SB-CSI report with full resolution. 
     As shown in  FIG. 12 , table  1200  includes a column with bit value  1202 , and in this case, four bit values “100”, “101”, “110”, and “111.” The table  1200  correlates each bit value with a representation of a SB-CSI report type  1204 . For example, the bit value “100” correlates with a NACK transmission and an SB-CSI report with full resolution and sub-band (SB) rank indication (RI). As another example, the bit value “101” correlates with a NACK transmission, an SB-CSI report with full resolution, and wideband RI. As yet another example, the bit value “110” correlates with an NACK transmission and a CSI configured report. As another example, the bit value “111” correlates with an ACK transmission. Thus, based on the table  1200  received from the base station  704 , the UE  702  may transmit a bit value to the base station  704  indicating a NACK or an ACK and whether the base station  704  should expect to receive an SB-CSI report with full resolution and one or more SB rank indications, an SB-CSI report with full resolution and one or more WB rank indications, or a CSI configured report. 
     As shown in  FIG. 13A , table  1300  includes a column with bit value  1302 , and in this case, two bit values “0” and “1.” The table  1300  correlates each bit value with a representation of an indication of an acknowledgement (ACK) transmission or an indication of a negative acknowledgement (NACK) transmission. For example, the bit value “0” correlates with a NACK transmission. As another example, the bit value “1” correlates with an ACK transmission. Thus, based on the table  1300  received from the base station  704 , the UE  702  may transmit a bit value to the base station  704  indicating a NACK or an ACK. 
     As shown in  FIG. 13B , table  1350  includes a column with bit value  1352 , and in this case, three bit values “00”, “01”, and “11.” The table  1350  correlates each bit value with a representation of an indication of an SB report type  1354 . For example, the bit value “00” correlates with transmitting a CSI configured report. As another example, the bit value “01” correlates with transmitting an SB CSI report with full resolution and WB rank indication. As yet another example, the bit value “11” correlates with transmitting an SB CSI report with full resolution and SB rank indication. Thus, based on the table  1350  received from the base station  704 , the UE  702  may transmit a bit value to the base station  704  indicating whether the base station  704  should expect to receive a CSI configured report, an SB-CSI report with full resolution and WB rank indication, or an SB-CSI report with full resolution and SB rank indication. 
     In some aspects, the bits values from the tables illustrated in  FIGS. 13A and 13B  may be combined in a transmission from the UE  702  to the base station  704 . For example, the UE  702  may transmit a bit value of “100” which indicates to the base station  704  that an ACK transmission is being transmitted and that a CSI configured report is to be transmitted to the base station. As another example, the UE  702  may transmit a bit value of “101” which indicates to the base station  704  that an ACK transmission is being transmitted and that an SB CSI report with full resolution and WB rank indication is to be transmitted to the base station. As another example, the UE  702  may transmit a bit value of “111” which indicates to the base station  704  that an ACK transmission is being transmitted and that an SB CSI report with full resolution and SB rank indication is to be transmitted to the base station. As yet another example, the UE  702  may transmit a bit value of “o00” which indicates to the base station  704  that a NACK transmission is being transmitted and that a CSI configured report is to be transmitted to the base station. As yet another example, the UE  702  may transmit a bit value of “001” which indicates to the base station  704  that a NACK transmission is being transmitted and that an SB CSI report with full resolution and WB rank indication is to be transmitted to the base station. As yet another example, the UE  702  may transmit a bit value of “011” which indicates to the base station  704  that a NACK transmission is being transmitted and that an SB CSI report with full resolution and SB rank indication is to be transmitted to the base station. 
     In some aspects, before receiving the PDSCH transmission from the base station  704 , the UE  702  may receive downlink control information (DCI) associated with the PDSCH transmission. The DCI may indicate a first modulation coding scheme (MCS) value associated with the PDSCH transmission. The UE  702  may also configure the reception of the DCI for receiving the PDSCH transmission. Subsequently, the UE  702  may receive the PDSCH transmission from the base station  704  and measure a second MCS value associated with the received PDSCH transmission. The UE  702  may determine whether to transmit a rank indication (RI) per sub-band, for example, with an SB-CSI report with full resolution for reception by the base station based on a threshold difference between the first MCS value and the second MCS value. For example, when the difference between the first MCS value and the second MCS value is greater than the threshold difference, the UE  702  may transmit the rank indication per sub-band. However, when the difference between the first MCS value and the second MCS value is no greater than the threshold difference, the UE  702  may abstain from transmitting the rank indication per sub-band. In some examples, the UE  702  may determine whether to transmit a wideband (WB) rank indication (RI), for example, with a CSI configured report for reception by the base station based on a threshold difference between the first MCS value and the second MCS value. For example, when the difference between the first MCS value and the second MCS value is greater than the threshold difference, the UE  702  may transmit the WB rank indication. However, when the difference between the first MCS value and the second MCS value is no greater than the threshold difference, the UE  702  may abstain from transmitting the WB rank indication. It should be understood that the threshold difference between the first MCS value and the second MCS value used to determine whether to include the RI per sub-band with the SB-CSI report may be the same threshold difference or a different threshold difference used to determine whether to include the WB RI with CSI configured report. 
       FIG. 14  is a block diagram illustrating an example of a hardware implementation for a user equipment (UE)  1400  employing a processing system  1414 . For example, the UE  1400  may be any of the user equipment (UEs) or base stations (e.g., gNB or eNB) illustrated in any one or more of  FIGS. 1-4 and 7 . 
     The UE  1400  may be implemented with a processing system  1414  that includes one or more processors  1404 . Examples of processors  1404  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  1400  may be configured to perform any one or more of the functions described herein. That is, the processor  1404 , as utilized in a UE  1400 , may be used to implement any one or more of the processes described herein. The processor  1404  may in some instances be implemented via a baseband or modem chip and in other implementations, the processor  1404  may itself comprise a number of devices distinct and different from a baseband or modem chip (e.g., in such scenarios is 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  1414  may be implemented with a bus architecture, represented generally by the bus  1402 . The bus  1402  may include any number of interconnecting buses and bridges depending on the specific application of the processing system  1414  and the overall design constraints. The bus  1402  communicatively couples together various circuits including one or more processors (represented generally by the processor  1404 ), and computer-readable media (represented generally by the computer-readable storage medium  1406 ). The bus  1402  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  1408  provides an interface between the bus  1402  and a transceiver  1410 . The transceiver  1410  provides a means for communicating with various other apparatus over a transmission medium (e.g., air interface). A user interface  1412  (e.g., keypad, display, speaker, microphone, joystick) may also be provided. 
     The processor  1404  is responsible for managing the bus  1402  and general processing, including the execution of software stored on the computer-readable storage medium  1406 . The software, when executed by the processor  1404 , causes the processing system  1414  to perform the various functions described herein for any particular apparatus. The computer-readable storage medium  1406  may also be used for storing data that is manipulated by the processor  1404  when executing software. 
     One or more processors  1404  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 storage medium  1406 . 
     The computer-readable storage medium  1406  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 storage medium  1406  may reside in the processing system  1414 , external to the processing system  1414 , or distributed across multiple entities including the processing system  1414 . The computer-readable storage medium  1406  may be embodied in a computer program product. 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  1404  may include circuitry configured for various functions. For example, the processor  1404  may include receiving circuitry  1440  configured to receive a physical downlink shared channel (PDSCH) transmission from a base station. The receiving circuitry  1440  may also be configured to receive downlink control information (DCI) associated with the PDSCH transmission, where the DCI indicates a first modulation coding scheme (MCS) value associated the PDSCH transmission. The receiving circuitry  1440  may also be configured to receive a control message from the base station indicating whether to transmit the SB-CSI report as the SB-CSI report with full resolution to the base station or whether to transmit the SB-CSI report as the CSI configured report. The receiving circuitry  1440  may be configured to execute receiving instructions  1450  stored in the computer-readable storage medium  1406  to implement any of the one or more of the functions described herein. 
     In some aspects of the disclosure, the processor  1404  may also include transmitting circuitry  1442  configured to transmit either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission to the base station in response to a reception of the PDSCH transmission. The transmitting circuitry  1442  may also be configured to transmit the SB-CSI report to the base station when the ACK transmission is transmitted to the base station and transmit the SB-CSI report to the base station when the NACK transmission is transmitted to the base station. The transmitting circuitry  1442  may also be configured to transmit the SB-CSI report to the base station when the NACK transmission is transmitted to the base station or abstain from transmitting the SB-CSI report when the ACK transmission is transmitted to the base station. The transmitting circuitry  1442  may be configured to execute transmitting instructions  1452  stored in the computer-readable storage medium  1406  to implement any of the one or more of the functions described herein. 
     In some aspects of the disclosure, the processor  1404  may further include determining circuitry  1444  configured to determine whether to transmit a sub-band (SB) channel state information (SB-CSI) report to the base station based on whether the ACK transmission is transmitted to the base station or whether the NACK transmission is transmitted to the base station. The determining circuitry  1444  may also be configured to, when determining to transmit the SB-CSI report to the base station, determine whether to transmit the SB-CSI report as an SB-CSI report with full resolution to the base station, where the SB-CSI report with full resolution includes one or more channel quality information (CQI) values each associated with a sub-band of a plurality of sub-bands utilized by the PDSCH transmission; or transmit the SB-CSI report as a channel state information (CSI) configured report including one or more spatial differential CQI values each associated with an offset level, where the offset level comprises a difference between a CQI value associated with a sub-band of the plurality of sub-bands utilized by the PDSCH transmission and an average CQI value associated with the plurality of sub-bands utilized by the PDSCH transmission. The determining circuitry  1444  may also be configured to, when determining to transmit the SB-CSI report as the SB-CSI report with full resolution to the base station, determine whether to include a rank indication per sub-band with the SB-CSI report with full resolution for reception by the base station, where the rank indication per sub-band indicates a quantity of sub-bands utilized by the PDSCH transmission that are able to be supported by the UE. The determining circuitry  1444  may be configured to execute receiving instructions  1454  stored in the computer-readable storage medium  1406  to implement any of the one or more of the functions described herein. 
     In some aspects of the disclosure, the processor  1404  may include configuring circuitry  1446  configured to configuring the reception of the DCI for receiving the PDSCH transmission. The configuring circuitry  1446  may be configured to execute configuring instructions  1456  stored in the computer-readable storage medium  1406  to implement any of the one or more of the functions described herein. 
     In some aspects of the disclosure, the processor  1404  may also include measuring circuitry  1448  configured to measuring a second MCS value associated with the received PDSCH transmission. The measuring circuitry  1448  may be configured to execute measuring instructions  1458  stored in the computer-readable storage medium  1406  to implement any of the one or more of the functions described herein. 
       FIG. 15  is a flow chart  1500  of a method for reporting sub-band (SB) channel state information (SB-CSI) 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  1400 , as described above, and illustrated in  FIG. 14 , by a processor or processing system, or by any suitable means for carrying out the described functions. 
     At block  1502 , the UE  1400  may receive a physical downlink shared channel (PDSCH) transmission from a base station. At block  1504 , the UE  1400  may transmit either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission to the base station in response to a reception of the PDSCH transmission. For example, the UE  1400  may receive the PDSCH transmission from the base station and attempt to decode the PDSCH transmission. Based on an ability of the UE  1400  to decode the PDSCH transmission, the UE  1400  may transmit either an ACK transmission or a NACK transmission. In some aspects, when the UE  1400  is unable to decode the PDSCH transmission, the UE  1400  may transmit a NACK transmission to the base station and when the UE  1400  is able to decode the PDSCH transmission, the UE  1400  may transmit an ACK transmission. 
     In some aspects, before receiving the PDSCH transmission from the base station, the UE  1400  may receive downlink control information (DCI) associated with the PDSCH transmission. The DCI may indicate a first modulation coding scheme (MCS) value associated with the PDSCH transmission. The UE  1400  may also configure the reception of the DCI for receiving the PDSCH transmission. Subsequently, the UE  1400  may receive the PDSCH transmission from the base station and measure a second MCS value associated with the received PDSCH transmission. The UE  1400  may transmit either the ACK transmission or the NACK transmission to the base station in response to receiving the PDSCH transmission and based on a threshold difference between the first MCS value and the second MCS value. For example, when the difference between the first MCS value and the second MCS value is greater than the threshold difference, the UE  1400  may transmit the NACK transmission. However, when the difference between the first MCS value and the second MCS value is no greater than the threshold difference, the UE  1400  may transmit the ACK transmission. 
     At block  1506 , the UE  1400  may determine whether to transmit an SB-CSI report to the base station based on whether the ACK transmission is transmitted to the base station or whether the NACK transmission is transmitted to the base station. In some aspects, the UE  1400  may determine to transmit an SB-CSI report to the base station when a NACK transmission is transmitted to the base station and may determine to abstain from transmitting an SB-CSI report to the base station when an ACK transmission is transmitted to the base station. In some examples, the UE  1400  may determine to transmit a CSI configured report to the base station, as described herein, when determining to abstain from transmitting an SB-CSI report to the base station. Alternatively, the UE  1400  may determine not to transmit a CSI configured report to the base station when determining to abstain from transmitting an SB-CSI report to the base station. In some aspects, the UE  1400  may determine to transmit an SB-CSI report to the base station when a NACK transmission is transmitted to the base station and/or when an ACK transmission is transmitted to the base station. For example, the UE  1400  may determine to transmit an SB-CSI report to the base station regardless of whether an ACK transmission or a NACK transmission is transmitted to the base station. 
     The UE  1400  may transmit the SB-CSI report to the base station based on whether the ACK transmission is transmitted to the base station or whether the NACK transmission is transmitted to the base station. In some aspects, the UE  1400  may transmit an SB-CSI report to the base station when a NACK transmission is transmitted to the base station and may abstain from transmitting an SB-CSI report to the base station when an ACK transmission is transmitted to the base station. In some examples, the UE  1400  may transmit a CSI configured report to the base station, as described herein, when abstaining from transmitting an SB-CSI report to the base station. Alternatively, the UE  1400  may not transmit a CSI configured report to the base station when abstaining from transmitting an SB-CSI report to the base station. In some aspects, the UE  1400  may transmit an SB-CSI report to the base station when a NACK transmission is transmitted to the base station and/or when an ACK transmission is transmitted to the base station. For example, the UE  1400  may transmit an SB-CSI report to the base station regardless of whether an ACK transmission or a NACK transmission is transmitted to the base station. 
     In some aspects, the when the UE  1400  determines to transmit the SB-CSI report to the base station, the UE  1400  may also include, with the SB-CSI report, SB reporting with full resolution, where the SB-CSI report with full resolution indicates one or more channel quality information (CQI) values each associated with a sub-band of a plurality of sub-bands utilized by the PDSCH transmission or SB reporting without full resolution, where the SB reporting without full resolution indicates one or more spatial differential CQI values each associated with an offset level, and where the offset level includes a difference between a CQI value associated with a sub-band of the plurality of sub-bands utilized by the PDSCH transmission and an average CQI value associated with the plurality of sub-bands utilized by the PDSCH transmission. In some examples, the one or more CQI values may include at least one of a CQI index, a modulation scheme, a code rate, or an efficiency. In some examples, the UE  1400  determining whether to transmit to the base station the SB-CSI report including the SB reporting with full resolution or transmit the SB-CSI report including the SB reporting without full resolution and having one or more spatial differential CQI values each associated with an offset level may be based on at least a quality of a decoding of the PDSCH transmission. 
     In some aspects, a table may be used as SB reporting with full resolution and may include a column of CQI indices, a column of modulations, a column of code rates, and a column of efficiencies. Each modulation, code rate, and efficiency in a particular row aligns with a CQI index sharing that same particular row. Each of the CQI indexes may be indicative of a particular sub-band. Generally, the SB reporting with full resolution provides better resolution than SB reporting without full resolution but also occupies a greater payload during transmission, for example, on a physical uplink control channel (PUCCH). Because of this, the UE  1400  may determine to include, with the transmission of the SB-CSI report, the SB reporting with full resolution when there is a bad signal or decoding of the PDSCH transmission fails in order to provide the base station with the resolution needed to remedy the bad signal or the failed decoding. 
     In some aspects, a table may be used as SB reporting without full resolution and may include a column of spatial differential CQI values and a column of offset levels. Each offset level in a particular row aligns with a spatial differential CQI index value sharing that same particular row. Generally, the SB reporting without full resolution does not provide the same amount of resolution that the SB reporting with full resolution provides. However, the SB reporting without full resolution also occupies a lesser payload than the SB reporting with full resolution during transmission, for example, on a physical uplink control channel (PUCCH). Because of this, the UE  1400  may determine to transmit the SB-CSI report including the SB reporting without full resolution to the base station when a signal is above a threshold or decoding of the PDSCH transmission is at least partially successful in order to provide the base station with some resolution at a reduced transmission payload. 
     In some aspects, the UE  1400  may determine not to transmit an SB-CSI report to the base station. For example, instead of transmitting an SB-CSI report to the base station, the UE  1400  may transmit a CSI configured report. A CSI configured report may include wideband (WB) reporting of CQI values and one or more WB rank indications (e.g., ranking a quantity or number of layers). In some aspects, a CSI configured report may include SB reporting without full resolution and also one or more WB rank indications. 
     In some examples, before the UE  1400  determines whether to transmit the SB-CSI report, the UE  1400  may receive from the base station a control message indicating whether the UE  1400  is to transmit the SB-CSI report including the SB reporting with full resolution to the base station or whether the UE  1400  is to transmit the SB-CSI report including. The UE  1400  may receive the control message and determine whether to transmit the SB-CSI report including the SB reporting with full resolution to the base station or to transmit the SB-CSI report with the SB reporting without full resolution based at least on the control message. In some aspects, the UE  1400  may receive the control message and determine to transmit a CSI configured report instead of an SB-CSI report based at least on the control message. The control message may include at least one of a radio resource control (RRC) message, a medium access control (MAC) control element (MAC-CE), or a downlink control information (DCI). 
     In some examples, the UE  1400  may include a rank indication (RI) with an SB-CSI report. An RI may be on a per sub-band basis and indicate a rank of a particular sub-band amongst a plurality of sub-bands. For example, in response to determining that a NACK transmission is transmitted to the base station, the UE  1400  may determine to include an RI with the SB-CSI report for transmission to the base station. In some aspects, the RI may indicate to the base station a quantity of sub-bands utilized by the PDSCH transmission that are able to be supported by the UE  1400 . 
     In some aspects, the base station may transmit to the UE  1400  a table through RRC signal or a medium access control (MAC) control element (MAC-CE) to correlate bit values with types of SB-CSI report transmissions. The UE  1400  may also provide an indication (e.g., one or more bit values) based on the table in an ACK transmission or a NACK transmission to the base station and in response to receiving the PDSCH transmission so that the base station expects to receive a particular type of SB-CSI report from the UE  1400 .  FIGS. 10, 11, 12, 13A, and 13B , described herein, are illustrations of tables correlating bits values with acknowledgement (ACK) transmission and negative acknowledgement (NACK) transmission types according to some aspects. As described herein, based on the tables received from the base station, the UE  1400  may transmit a bit value to the base station indicating a NACK or an ACK and whether the base station should expect to receive SB reporting with full resolution, SB reporting without full resolution, or a CSI configured report as well as whether the base station should expect to receive a SB rank indication or a WB rank indication. 
     In some aspects, before receiving the PDSCH transmission from the base station, the UE  1400  may receive downlink control information (DCI) associated with the PDSCH transmission. The DCI may indicate a first modulation coding scheme (MCS) value associated with the PDSCH transmission. The UE  1400  may also configure the reception of the DCI for receiving the PDSCH transmission. Subsequently, the UE  1400  may receive the PDSCH transmission from the base station and measure a second MCS value associated with the received PDSCH transmission. The UE  1400  may determine whether to transmit a rank indication (RI) per sub-band, for example, with an SB-CSI report with full resolution for reception by the base station based on a threshold difference between the first MCS value and the second MCS value. For example, when the difference between the first MCS value and the second MCS value is greater than the threshold difference, the UE  1400  may transmit the rank indication per sub-band. However, when the difference between the first MCS value and the second MCS value is no greater than the threshold difference, the UE  1400  may abstain from transmitting the rank indication per sub-band. In some examples, the UE  1400  may determine whether to transmit a wideband (WB) rank indication (RI), for example, with a CSI configured report for reception by the base station based on a threshold difference between the first MCS value and the second MCS value. For example, when the difference between the first MCS value and the second MCS value is greater than the threshold difference, the UE  1400  may transmit the WB rank indication. However, when the difference between the first MCS value and the second MCS value is no greater than the threshold difference, the UE  1400  may abstain from transmitting the WB rank indication. It should be understood that the threshold difference between the first MCS value and the second MCS value used to determine whether to include the RI per sub-band with the SB-CSI report may be the same threshold difference or a different threshold difference used to determine whether to include the WB RI with CSI configured report. 
       FIG. 16  is a flow chart  1600  of a method for reporting sub-band (SB) channel state information (SB-CSI) 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  1400 , as described above, and illustrated in  FIG. 14 , by a processor or processing system, or by any suitable means for carrying out the described functions. 
     At block  1602 , the UE  1400  may receive a physical downlink shared channel (PDSCH) transmission from a base station. The features of block  1602  may be the same as or at least similar to one or more features described herein at least with respect to block  1502  of  FIG. 15 . At block  1604 , the UE  1400  may transmit either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission to the base station in response to a reception of the PDSCH transmission. The features of block  1604  may be the same as or at least similar to one or more features described herein at least with respect to block  1504  of  FIG. 15 . 
     At block  1606 , the UE  1400  may determine whether an ACK transmission has been transmitted to the base station. If the UE  1400  determines that an ACK transmission has been transmitted to the base station, for example, in response to a reception of the PDSCH transmission, then, at block  1608 , the UE  1400  may determine to end the process. For example, the UE  1400  may determine not to transmit an SB-CSI report to the base station. If the UE  1400  determines that an ACK transmission has not be transmitted to the base station, for example, in response to a reception of the PDSCH transmission, then, at block  1610 , the UE  1400  may transmit the SB-CSI report to the base station with SB reporting with full resolution. 
       FIG. 17  is a flow chart  1700  of a method for reporting sub-band (SB) channel state information (SB-CSI) 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  1400 , as described above, and illustrated in  FIG. 14 , by a processor or processing system, or by any suitable means for carrying out the described functions. 
     At block  1702 , the UE  1400  may receive a physical downlink shared channel (PDSCH) transmission from a base station. The features of block  1702  may be the same as or at least similar to one or more features described herein at least with respect to block  1502  of  FIG. 15 . At block  1704 , the UE  1400  may transmit either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission to the base station in response to a reception of the PDSCH transmission. The features of block  1704  may be the same as or at least similar to one or more features described herein at least with respect to block  1504  of  FIG. 15 . 
     At block  1706 , the UE  1400  may determine whether an ACK transmission has been transmitted to the base station. If the UE  1400  determines that an ACK transmission has been transmitted to the base station, for example, in response to a reception of the PDSCH transmission, then, at block  1708 , the UE  1400  may determine to end the process. For example, the UE  1400  may determine not to transmit an SB-CSI report to the base station. If the UE  1400  determines that an ACK transmission has not be transmitted to the base station, for example, in response to a reception of the PDSCH transmission, then, at block  1710 , the UE  1400  may determine whether the SB-CSI report is to be transmitted to the base station as a SB-CSI report with full resolution. If the UE  1400  determines that the SB-CSI report is to be transmitted to the base station as an SB-CSI report with full resolution, then, at block  1712 , the UE  1400  may transmit the SB-CSI report to the base station with SB reporting with full resolution. If the UE  1400  determines that the SB-CSI report is not to be transmitted to the base station as an SB-CSI report with full resolution, then, at block  1714 , the UE  1400  may transmit the SB-CSI report to the base station as a CSI configured report or with SB reporting without full resolution. 
       FIG. 18  is a flow chart  1800  of a method for reporting sub-band (SB) channel state information (SB-CSI) 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  1400 , as described above, and illustrated in  FIG. 14 , by a processor or processing system, or by any suitable means for carrying out the described functions. 
     At block  1802 , the UE  1400  may receive a physical downlink shared channel (PDSCH) transmission from a base station. The features of block  1802  may be the same as or at least similar to one or more features described herein at least with respect to block  1502  of  FIG. 15 . At block  1804 , the UE  1400  may transmit either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission to the base station in response to a reception of the PDSCH transmission. The features of block  1804  may be the same as or at least similar to one or more features described herein at least with respect to block  1504  of  FIG. 15 . 
     At block  1806 , the UE  1400  may determine to transmit an SB-CSI report to the base station. For example, regardless of whether the UE  1400  transmits an ACK transmission or a NACK transmission, the UE  1400  may subsequently determine to transmit an SB-CSI report to the base station. At block  1808 , the UE  1400  may determine whether the SB-CSI report is to be transmitted to the base station as a SB-CSI report with full resolution. If the UE  1400  determines that the SB-CSI report is to be transmitted to the base station as an SB-CSI report with full resolution, then, at block  1810 , the UE  1400  may transmit the SB-CSI report to the base station as an SB-CSI report with full resolution. If the UE  1400  determines that the SB-CSI report is not to be transmitted to the base station as an SB-CSI report with full resolution, then, at block  1812 , the UE  1400  may transmit the SB-CSI report to the base station with SB reporting without full resolution or the UE  1400  may transmit a CSI configured report. 
       FIG. 19  is a flow chart  1900  of a method for reporting SB-CSI 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  1400 , as described above, and illustrated in  FIG. 14 , by a processor or processing system, or by any suitable means for carrying out the described functions. 
     At block  1902 , the UE  1400  may receive a physical downlink shared channel (PDSCH) transmission from a base station. The features of block  1902  may be the same as or at least similar to one or more features described herein at least with respect to block  1502  of  FIG. 15 . At block  1904 , the UE  1400  may transmit either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission to the base station in response to a reception of the PDSCH transmission. The features of block  1904  may be the same as or at least similar to one or more features described herein at least with respect to block  1504  of  FIG. 15 . 
     At block  1906 , the UE  1400  may receive a control message from the base station indicating whether to transmit an SB-CSI report to the base station as an SB-CSI report with full resolution or whether to transmit the SB-CSI report as a CSI configured report. In some aspects, the control message may include at least one of a radio resource control (RRC) message, a medium access control (MAC) control element (MAC-CE), or a downlink control information (DCI). 
     At block  1908 , the UE  1400  may determine whether an ACK transmission has been transmitted to the base station. If the UE  1400  determines that an ACK transmission has been transmitted to the base station, for example, in response to a reception of the PDSCH transmission, then, at block  1910 , the UE  1400  may determine to end the process. For example, the UE  1400  may determine not to transmit an SB-CSI report to the base station. If the UE  1400  determines that an ACK transmission has not be transmitted to the base station, for example, in response to a reception of the PDSCH transmission, then, at block  1912 , the UE  1400  may determine whether the SB-CSI report is to be transmitted to the base station is to include SB reporting with full resolution. If the UE  1400  determines that the SB-CSI report is to be transmitted to the base station including SB reporting with full resolution, then, at block  1914 , the UE  1400  may transmit the SB-CSI report to the base station including SB reporting with full resolution. If the UE  1400  determines that the SB-CSI report is not to be transmitted to the base station including SB reporting with full resolution, then, at block  1916 , the UE  1400  may transmit the SB-CSI report to the base station including SB reporting without full resolution or the UE  1400  may transmit a CSI configured report. 
       FIG. 20  is a flow chart  2000  of a method for reporting SB-CSI 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  1400 , as described above, and illustrated in  FIG. 14 , by a processor or processing system, or by any suitable means for carrying out the described functions. 
     At block  2002 , the UE  1400  may receive downlink control information (DCI) associated with a PDSCH transmission and indicating a first modulation code scheme (MCS) value associated with the PDSCH transmission. At block  2004 , the UE  1400  may configure the reception of the DCI for receiving the PDSCH transmission. At block  2006 , the UE  1400  may receive a physical downlink shared channel (PDSCH) transmission from a base station. The features of block  2006  may be the same as or at least similar to one or more features described herein at least with respect to block  1502  of  FIG. 15 . At block  2008 , the UE  1400  may measure a second MCS value associated with the PDSCH transmission. At block  2010 , the UE  1400  may transmit either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission to the base station in response to a reception of the PDSCH transmission. The features of block  2010  may be the same as or at least similar to one or more features described herein at least with respect to block  1504  of  FIG. 15 . 
     At block  2012 , the UE  1400  may determine whether an ACK transmission has been transmitted to the base station. If the UE  1400  determines that an ACK transmission has been transmitted to the base station, for example, in response to a reception of the PDSCH transmission, then, at block  2014 , the UE  1400  may determine to end the process. For example, the UE  1400  may determine not to transmit an SB-CSI report to the base station. If the UE  1400  determines that an ACK transmission has not be transmitted to the base station, for example, in response to a reception of the PDSCH transmission, then, at block  2016 , the UE  1400  may determine whether the SB-CSI report is to be transmitted to the base station with SB reporting with full resolution. If the UE  1400  determines that the SB-CSI report is to be transmitted to the base station with SB reporting with full resolution, then, at block  2018 , the UE  1400  may transmit the SB-CSI report to the base station as an SB-CSI report with full resolution. If the UE  1400  determines that the SB-CSI report is not to be transmitted to the base station with SB reporting with full resolution, then, at block  2020 , the UE  1400  may transmit the SB-CSI report to the base station with SB reporting without full resolution or the UE  1400  may transmit a CSI configured report. 
       FIG. 21  is a flow chart  2100  of a method for reporting SB-CSI 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  1400 , as described above, and illustrated in  FIG. 14 , by a processor or processing system, or by any suitable means for carrying out the described functions. 
     At block  2102 , the UE  1400  may receive a physical downlink shared channel (PDSCH) transmission from a base station. At block  2104 , the UE  1400  may transmit either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission to the base station in response to a reception of the PDSCH transmission. At block  2106 , the UE  1400  may determine whether to transmit an SB-CSI report with a rank indication (RI) to the base station based on whether the ACK transmission is transmitted to the base station or whether the NACK transmission is transmitted to the base station. 
       FIG. 22  is a flow chart  2200  of a method for reporting SB-CSI 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  1400 , as described above, and illustrated in  FIG. 14 , by a processor or processing system, or by any suitable means for carrying out the described functions. 
     At block  2202 , the UE  1400  may receive a physical downlink shared channel (PDSCH) transmission from a base station. The features of block  2202  may be the same as or at least similar to one or more features described herein at least with respect to block  1502  of  FIG. 15 . At block  2204 , the UE  1400  may transmit either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission to the base station in response to a reception of the PDSCH transmission. The features of block  2204  may be the same as or at least similar to one or more features described herein at least with respect to block  1504  of  FIG. 15 . 
     At block  2206 , the UE  1400  may determine whether an ACK transmission has been transmitted to the base station. If the UE  1400  determines that an ACK transmission has been transmitted to the base station, for example, in response to a reception of the PDSCH transmission, then, at block  2208 , the UE  1400  may determine to end the process. For example, the UE  1400  may determine not to transmit an SB-CSI report to the base station. If the UE  1400  determines that an ACK transmission has not be transmitted to the base station, for example, in response to a reception of the PDSCH transmission, then, at block  2210 , the UE  1400  may transmit the SB-CSI report to the base station with SB reporting with full resolution and one or more SB rank indications. 
       FIG. 23  is a flow chart  2300  of a method for reporting SB-CSI 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  1400 , as described above, and illustrated in  FIG. 14 , by a processor or processing system, or by any suitable means for carrying out the described functions. 
     At block  2302 , the UE  1400  may receive a physical downlink shared channel (PDSCH) transmission from a base station. The features of block  2302  may be the same as or at least similar to one or more features described herein at least with respect to block  1502  of  FIG. 15 . At block  2304 , the UE  1400  may transmit either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission to the base station in response to a reception of the PDSCH transmission. The features of block  2304  may be the same as or at least similar to one or more features described herein at least with respect to block  1504  of  FIG. 15 . 
     At block  2306 , the UE  1400  may determine whether an ACK transmission has been transmitted to the base station. If the UE  1400  determines that an ACK transmission has been transmitted to the base station, for example, in response to a reception of the PDSCH transmission, then, at block  2308 , the UE  1400  may determine to end the process. For example, the UE  1400  may determine not to transmit an SB-CSI report to the base station. If the UE  1400  determines that an ACK transmission has not be transmitted to the base station, for example, in response to a reception of the PDSCH transmission, then, at block  2310 , the UE  1400  may determine whether the SB-CSI report is to be transmitted to the base station as a SB-CSI report with full resolution. If the UE  1400  determines that the SB-CSI report is not to be transmitted to the base station as an SB-CSI report with full resolution, then, at block  2312 , the UE  1400  may transmit the SB-CSI report to the base station with SB reporting without full resolution or the UE  1400  may transmit a CSI configured report. If the UE  1400  determines that the SB-CSI report is to be transmitted to the base station as an SB-CSI report with full resolution, then, at block  2314 , the UE  1400  may determine whether the SB-CSI report with full resolution is to include an SB rank indication (RI). If the UE  1400  determines that the SB-CSI report with full resolution is to include an SB RI, then, at block  2316 , the UE  1400  may transmit the SB-CSI report to the base station as an SB-CSI report with full resolution and one or more SB rank indications. If the UE  1400  determines that the SB-CSI report with full resolution is not to include an RI, then, at block  2318 , the UE  1400  may transmit the SB-CSI report to the base station as an SB-CSI report with full resolution and without SB rank indication. 
       FIG. 24  is a flow chart  1800  of a method for reporting SB-CSI 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  1400 , as described above, and illustrated in  FIG. 14 , by a processor or processing system, or by any suitable means for carrying out the described functions. 
     At block  2402 , the UE  1400  may receive a physical downlink shared channel (PDSCH) transmission from a base station. The features of block  2402  may be the same as or at least similar to one or more features described herein at least with respect to block  1502  of  FIG. 15 . At block  2404 , the UE  1400  may transmit either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission to the base station in response to a reception of the PDSCH transmission. The features of block  2404  may be the same as or at least similar to one or more features described herein at least with respect to block  1504  of  FIG. 15 . 
     At block  2406 , the UE  1400  may determine to transmit an SB-CSI report to the base station. For example, regardless of whether the UE  1400  transmits an ACK transmission or a NACK transmission, the UE  1400  may subsequently determine to transmit an SB-CSI report to the base station. At block  2408 , the UE  1400  may determine whether the SB-CSI report is to be transmitted to the base station with SB reporting with full resolution. If the UE  1400  determines that the SB-CSI report is not to be transmitted to the base station with SB reporting with full resolution, then, at block  2410 , the UE  1400  may transmit the SB-CSI report to the base station with SB reporting without full resolution or the UE  1400  may transmit a CSI configured report. If the UE  1400  determines that the SB-CSI report is to be transmitted to the base station with SB reporting with full resolution, then, at block  2412 , the UE  1400  may determine whether the SB-CSI report with SB reporting with full resolution is to include an SB rank indication (RI). If the UE  1400  determines that the SB-CSI report with SB reporting with full resolution is to include an SB RI, then, at block  2414 , the UE  1400  may transmit the SB-CSI report to the base station with SB reporting with full resolution and one or more SB rank indications. If the UE  1400  determines that the SB-CSI report with full resolution is not to include an SB RI, then, at block  2416 , the UE  1400  may transmit the SB-CSI report to the base station with SB reporting with full resolution and without an SB rank indication. 
       FIG. 25  is a flow chart  2500  of a method for reporting SB-CSI 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  1400 , as described above, and illustrated in  FIG. 14 , by a processor or processing system, or by any suitable means for carrying out the described functions. 
     At block  2502 , the UE  1400  may receive a physical downlink shared channel (PDSCH) transmission from a base station. The features of block  2502  may be the same as or at least similar to one or more features described herein at least with respect to block  1502  of  FIG. 15 . At block  2504 , the UE  1400  may transmit either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission to the base station in response to a reception of the PDSCH transmission. The features of block  2504  may be the same as or at least similar to one or more features described herein at least with respect to block  1504  of  FIG. 15 . 
     At block  2506 , the UE  1400  may receive a control message from the base station indicating whether to transmit an SB-CSI report to the base station as an SB-CSI report with full resolution or whether to transmit the SB-CSI report as a CSI configured report. In some aspects, the control message may include at least one of a radio resource control (RRC) message, a medium access control (MAC) control element (MAC-CE), or a downlink control information (DCI). 
     At block  2508 , the UE  1400  may determine whether an ACK transmission has been transmitted to the base station. If the UE  1400  determines that an ACK transmission has been transmitted to the base station, for example, in response to a reception of the PDSCH transmission, then, at block  2510 , the UE  1400  may determine to end the process. For example, the UE  1400  may determine not to transmit an SB-CSI report to the base station. If the UE  1400  determines that an ACK transmission has not be transmitted to the base station, for example, in response to a reception of the PDSCH transmission, then, at block  2512 , the UE  1400  may, based on the control message, determine whether the SB-CSI report is to be transmitted to the base station with SB reporting with full resolution. If the UE  1400  determines that the SB-CSI report is not to be transmitted to the base station with SB reporting with full resolution, then, at block  2514 , the UE  1400  may transmit the SB-CSI report to the base station with SB reporting without full resolution or the UE  1400  may transmit a CSI configured report. If the UE  1400  determines that the SB-CSI report is to be transmitted to the base station with SB reporting with full resolution, then, at block  2516 , the UE  1400  may determine whether the SB-CSI report with SB reporting with full resolution is to include an SB rank indication (RI). If the UE  1400  determines that the SB-CSI report with SB reporting with full resolution is to include an SB RI, then, at block  2518 , the UE  1400  may transmit the SB-CSI report to the base station with SB reporting with full resolution and one or more SB rank indications. If the UE  1400  determines that the SB-CSI report with SB reporting with full resolution is not to include an SB RI, then, at block  2520 , the UE  1400  may transmit the SB-CSI report to the base station with SB reporting with full resolution and without an SB RI. 
       FIG. 26  is a flow chart  2600  of a method for reporting SB-CSI 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  1400 , as described above, and illustrated in  FIG. 14 , by a processor or processing system, or by any suitable means for carrying out the described functions. 
     At block  2602 , the UE  1400  may receive downlink control information (DCI) associated with a PDSCH transmission and indicating a first modulation code scheme (MCS) value associated with the PDSCH transmission. At block  2604 , the UE  1400  may configure the reception of the DCI for receiving the PDSCH transmission. At block  2606 , the UE  1400  may receive a physical downlink shared channel (PDSCH) transmission from a base station. The features of block  2606  may be the same as or at least similar to one or more features described herein at least with respect to block  1502  of  FIG. 15 . At block  2608 , the UE  1400  may measure a second MCS value associated with the PDSCH transmission. At block  2610 , the UE  1400  may transmit either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission to the base station in response to a reception of the PDSCH transmission. The features of block  2610  may be the same as or at least similar to one or more features described herein at least with respect to block  1504  of  FIG. 15 . 
     At block  2612 , the UE  1400  may determine whether an ACK transmission has been transmitted to the base station. If the UE  1400  determines that an ACK transmission has been transmitted to the base station, for example, in response to a reception of the PDSCH transmission, then, at block  2614 , the UE  1400  may determine to end the process. For example, the UE  1400  may determine not to transmit an SB-CSI report to the base station. If the UE  1400  determines that an ACK transmission has not be transmitted to the base station, for example, in response to a reception of the PDSCH transmission, then, at block  2616 , the UE  1400  may determine whether the SB-CSI report is to be transmitted to the base station with SB reporting with full resolution. If the UE  1400  determines that the SB-CSI report is not to be transmitted to the base station with SB reporting with full resolution, then, at block  2618 , the UE  1400  may transmit the SB-CSI report to the base station with SB reporting without full resolution or the UE  1400  may transmit a CSI configured report to the base station. If the UE  1400  determines that the SB-CSI report is to be transmitted to the base station with SB reporting with full resolution, then, at block  2620 , the UE  1400  may determine whether the SB-CSI report with SB reporting with full resolution is to include an SB rank indication (RI). If the UE  1400  determines that the SB-CSI report with SB reporting with full resolution is to include SB RI, then, at block  2622 , the UE  1400  may transmit the SB-CSI report to the base station with SB reporting with full resolution and one or more SB RIs. If the UE  1400  determines that the SB-CSI report with SB reporting with full resolution is not to include an SB RI, then, at block  2624 , the UE  1400  may transmit the SB-CSI report to the base station with SB reporting with full resolution and without SB RI. 
     In one configuration, the UE  1400  includes means for performing the various functions and processes described in relation to  FIGS. 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, and 26 . In one aspect, the aforementioned means may be the processor  1404  shown in  FIG. 14  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  1404  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  1406 , or any other suitable apparatus or means described in any one of the  FIGS. 1-4 and 7  and utilizing, for example, the processes and/or algorithms described herein in relation to  FIGS. 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, and 26 . 
       FIG. 27  is a block diagram illustrating an example of a hardware implementation for a network entity or a base station  2700  employing a processing system  2714  according to some aspects. For example, the network entity or the base station  2700  may correspond to any of the devices or systems shown and described herein in any one or more of  FIGS. 1-4 and 7 . 
     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  2714  that includes one or more processors  2704 . The processing system  2714  may be substantially the same as the processing system  1414  illustrated in  FIG. 14 , including a bus interface  2708 , a bus  2702 , a processor  2704 , and a computer-readable storage medium  2706 . Furthermore, the base station  2700  may include a user interface  2712  and a transceiver  2710  substantially similar to those described above in  FIG. 14 . That is, the processor  2704 , as utilized in the base station  2700 , may be used to implement any one or more of the processes described herein. 
     In some aspects of the disclosure, the processor  2704  may include circuitry configured for various functions. For example, the processor  2704  may include transmitting circuitry  2740  configured to transmit a physical downlink shared channel (PDSCH) transmission to a user equipment (UE). The transmitting circuitry  2740  may also be configured to transmit downlink control information (DCI) associated with the PDSCH transmission, where the DCI indicates a first modulation coding scheme (MCS) value associated with the PDSCH transmission. The transmitting circuitry  2740  may further be configured to transmit a control message to the UE indicating whether the UE is to transmit the SB-CSI report as the SB-CSI report with full resolution or whether to the UE is to transmit the SB-CSI report as a CSI configured report. The transmitting circuitry  2740  may be configured to transmit downlink control information (DCI) associated with the PDSCH transmission, where the DCI includes a first modulation coding scheme (MCS) value associated with the PDSCH transmission. The transmitting circuitry  2740  may be configured to execute transmitting instructions  2750  stored in the computer-readable storage medium  2706  to implement any of the one or more of the functions described herein. 
     In some aspects of the disclosure, the processor  2704  may also include receiving circuitry  2742  configured to receive either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission from the UE in response to the transmission of the PDSCH transmission. The receiving circuitry  2742  may also be configured to receive a sub-band (SB) channel state information (SB-CSI) report from the UE based on whether the ACK transmission is transmitted by the UE or the NACK transmission is transmitted by the UE. The receiving circuitry  2742  may further be configured to receive the SB-CSI report from the UE when the ACK transmission is received from the UE and receive the SB-CSI report from the UE when the NACK transmission is received from the UE. The receiving circuitry  2742  may be configured to receive receiving the SB-CSI report from the UE when the NACK transmission is received from the UE or determine that the SB-CSI report is not received from the UE when the ACK transmission is received from the UE. The receiving circuitry  2742  may further be configured to execute receiving instructions  2752  stored in the computer-readable storage medium  2706  to implement any of the one or more of the functions described herein. 
     In some aspects of the disclosure, the processor  2704  may further include determining circuitry  2744  configured to determine that the SB-CSI report is not received from the UE when the ACK transmission is received from the UE. The determining circuitry  2744  may further be configured to execute determining instructions  2754  stored in the computer-readable storage medium  2706  to implement any of the one or more of the functions described herein. 
       FIG. 28  is a flow chart  2800  of a method for reporting sub-band (SB) channel state information (SB-CSI) 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 base station  2700 , as described above, and illustrated in  FIG. 27 , by a processor or processing system, or by any suitable means for carrying out the described functions. 
     At block  2802 , the base station  2700  may transmit a physical downlink shared channel (PDSCH) transmission to a UE. At block  2804 , the base station  2700  may receive either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission from the UE in response to a transmission of the PDSCH transmission. For example, the base station  2700  may transmit the PDSCH transmission to the UE. Subsequently, the UE may receive the PDSCH transmission and attempt to decode the PDSCH transmission. Based on an ability of the UE to decode the PDSCH transmission, the base station  2700  may receive from the UE either an ACK transmission or a NACK transmission. In some aspects, when the UE is unable to decode the PDSCH transmission, the base station  2700  may receive from the UE a NACK transmission and when the UE is able to decode the PDSCH transmission, the base station  2700  may receive from the UE an ACK transmission. 
     In some aspects, before receiving the PDSCH transmission from the base station  2700 , the base station  2700  may transmit to the UE downlink control information (DCI) associated with the PDSCH transmission. The DCI may indicate a first modulation coding scheme (MCS) value associated with the PDSCH transmission. The UE may configure the reception of the DCI for receiving the PDSCH transmission. Subsequently, the base station  2700  may transmit the PDSCH transmission to the UE so that the UE may measure a second MCS value associated with the received PDSCH transmission. The base station  2700  may receive either the ACK transmission or the NACK transmission from the UE in response to transmitting the PDSCH transmission and based on a threshold difference between the first MCS value and the second MCS value. For example, when the difference between the first MCS value and the second MCS value is greater than the threshold difference, the base station  2700  may receive the NACK transmission. However, when the difference between the first MCS value and the second MCS value is no greater than the threshold difference, the base station  2700  may receive the ACK transmission. 
     At block  2806 , the base station  2700  may receive an SB-CSI report from the UE based on whether the ACK transmission is received from the UE or whether the NACK transmission is received from the UE. In some aspects, the base station  2700  may receive an SB-CSI report from the UE when a NACK transmission is received from the UE and may not receive an SB-CSI report from the UE when an ACK transmission is received from the UE. In some examples, the base station  2700  may receive a CSI configured report from the UE, as described herein, when an SB-CSI report is not received from the UE. Alternatively, the base station  2700  may not receive a CSI configured report from the UE when an SB-CSI report is not received from the UE. In some aspects, the base station  2700  may receive an SB-CSI report from the UE when a NACK transmission is received from the UE and/or when an ACK transmission is received from the UE. For example, the base station  2700  may receive an SB-CSI report from the UE regardless of whether an ACK transmission or a NACK transmission is received from the UE. 
     In some aspects, when the base station  2700  receives the SB-CSI report from the UE, the SB-CSI report may include SB reporting with full resolution, where the SB-CSI report with full resolution indicates one or more channel quality information (CQI) values each associated with a sub-band of a plurality of sub-bands utilized by the PDSCH transmission or SB reporting without full resolution, where the SB reporting without full resolution indicates one or more spatial differential CQI values each associated with an offset level, and where the offset level includes a difference between a CQI value associated with a sub-band of the plurality of sub-bands utilized by the PDSCH transmission and an average CQI value associated with the plurality of sub-bands utilized by the PDSCH transmission. In some examples, the one or more CQI values may include at least one of a CQI index, a modulation scheme, a code rate, or an efficiency. In some examples, the base station  2700  receiving the SB-CSI report including the SB reporting with full resolution or the SB-CSI report including the SB reporting without full resolution and having one or more spatial differential CQI values each associated with an offset level may be based on at least a quality of a decoding of the PDSCH transmission. 
     In some aspects, a table may be used as SB reporting with full resolution and may include a column of CQI indices, a column of modulations, a column of code rates, and a column of efficiencies. Each modulation, code rate, and efficiency in a particular row aligns with a CQI index sharing that same particular row. Each of the CQI indexes may be indicative of a particular sub-band. Generally, the SB reporting with full resolution provides better resolution than SB reporting without full resolution but also occupies a greater payload during transmission, for example, on a physical uplink control channel (PUCCH). Because of this, the SB-CSI report may include the SB reporting with full resolution when there is a bad signal or decoding of the PDSCH transmission fails in order to provide the base station  2700  with the resolution needed to remedy the bad signal or the failed decoding. 
     In some aspects, a table may be used as SB reporting without full resolution and may include a column of spatial differential CQI values and a column of offset levels. Each offset level in a particular row aligns with a spatial differential CQI index value sharing that same particular row. Generally, the SB reporting without full resolution does not provide the same amount of resolution that the SB reporting with full resolution provides. However, the SB reporting without full resolution also occupies a lesser payload than the SB reporting with full resolution during transmission, for example, on a physical uplink control channel (PUCCH). Because of this, the SB-CSI report may include the SB reporting without full resolution when a signal is above a threshold or decoding of the PDSCH transmission is at least partially successful in order to provide the base station  2700  with some resolution at a reduced transmission payload. 
     In some aspects, the base station  2700  may not receive an SB-CSI report from the UE. For example, instead of receiving an SB-CSI report from the UE, the base station  2700  may receive a CSI configured report. A CSI configured report may include wideband (WB) reporting of CQI values and one or more WB rank indications (e.g., ranking a quantity or number of layers). In some aspects, a CSI configured report may include SB reporting without full resolution and also one or more WB rank indications. 
     In some examples, before the base station  2700  receives the SB-CSI report, the base station  2700  may transmit to the UE a control message indicating whether the UE is to transmit the SB-CSI report including the SB reporting with full resolution to the base station  2700  or whether the UE is to transmit the SB-CSI report including. The UE may receive the control message and determine whether to transmit the SB-CSI report including the SB reporting with full resolution to the base station  2700  or to transmit the SB-CSI report with the SB reporting without full resolution based at least on the control message. In some aspects, the base station  2700  may transmit the control message to the UE so that the UE may determine whether to transmit a CSI configured report instead of an SB-CSI report based at least on the control message. The control message may include at least one of a radio resource control (RRC) message, a medium access control (MAC) control element (MAC-CE), or a downlink control information (DCI). 
     In some examples, the SB-CSI report may include a rank indicator (RI). An RI may be on a per sub-band basis and indicate a rank of a particular sub-band amongst a plurality of sub-bands. For example, in response to the UE determining that a NACK transmission is transmitted to the base station, the base station  2700  may receive an SB-CSI report from the UE that includes an RI. In some aspects, the RI may indicate to the base station  2700  a quantity of sub-bands utilized by the PDSCH transmission that are able to be supported by the UE. 
     In some aspects, the base station  2700  may transmit to the UE a table through RRC signal or a medium access control (MAC) control element (MAC-CE) to correlate bit values with types of SB-CSI report transmissions. The base station  2700  may also receive from the UE an indication (e.g., one or more bit values) based on the table in an ACK transmission or a NACK transmission in response to transmitting the PDSCH transmission to the UE. By receiving the indication in the ACK transmission or the NACK transmission, the base station  2700  may expect to receive a particular type of SB-CSI report from the UE.  FIGS. 10, 11, 12, 13A, and 13B , described herein, are illustrations of tables correlating bits values with acknowledgement (ACK) transmission and negative acknowledgement (NACK) transmission types according to some aspects. As described herein, based on the tables transmitted by the base station  2700  to the UE, the base station  2700  may receive a bit value from the UE indicating a NACK or an ACK and whether the base station  2700  should expect to receive SB reporting with full resolution, SB reporting without full resolution, or a CSI configured report as well as whether the base station  2700  should expect to receive a SB rank indication or a WB rank indication. 
     In some aspects, before the base station  2700  transmits the PDSCH transmission to the UE, the base station  2700  may transmit downlink control information (DCI) associated with the PDSCH transmission. The DCI may indicate a first modulation coding scheme (MCS) value associated with the PDSCH transmission. The UE may also configure the reception of the DCI for receiving the PDSCH transmission. Subsequently, the base station  2700  may transmit the PDSCH transmission to the UE so that the UE may measure a second MCS value associated with the PDSCH transmission. The UE may determine whether to transmit a rank indication (RI) per sub-band, for example, with an SB-CSI report with full resolution for reception by the base station  2700  based on a threshold difference between the first MCS value and the second MCS value. For example, when the difference between the first MCS value and the second MCS value is greater than the threshold difference, the base station  2700  may receive the rank indication per sub-band. However, when the difference between the first MCS value and the second MCS value is no greater than the threshold difference, the base station  2700  may not receive the rank indication per sub-band from the UE. In some examples, the UE  2700  may determine whether to transmit a wideband (WB) rank indication (RI), for example, with a CSI configured report for reception by the base station  2700  based on a threshold difference between the first MCS value and the second MCS value. For example, when the difference between the first MCS value and the second MCS value is greater than the threshold difference, the base station  2700  may receive the WB rank indication. However, when the difference between the first MCS value and the second MCS value is no greater than the threshold difference, the base station  2700  may not receive the WB rank indication from the UE. It should be understood that the threshold difference between the first MCS value and the second MCS value used to determine whether to include the RI per sub-band with the SB-CSI report may be the same threshold difference or a different threshold difference used to determine whether to include the WB RI with CSI configured report. 
       FIG. 29  is a flow chart  2900  of a method for reporting SB-CSI 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 base station  2700 , as described above, and illustrated in  FIG. 27 , by a processor or processing system, or by any suitable means for carrying out the described functions. 
     At block  2902 , the base station  2700  may transmit a physical downlink shared channel (PDSCH) transmission to a UE. The features of block  2902  may be the same as or at least similar to one or more features described herein at least with respect to block  2802  of  FIG. 28 . At block  2904 , the base station  2700  may receive either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission from the UE in response to a transmission of the PDSCH transmission. The features of block  2904  may be the same as or at least similar to one or more features described herein at least with respect to block  2804  of  FIG. 28 . At block  2906 , the base station  2700  may determine whether an ACK transmission has been received from the UE. If the base station  2700  determines that an ACK transmission has been received from the UE, for example, in response to a transmission of the PDSCH transmission, then the method ends. If the base station  2700  determines that an ACK transmission has not be received from the UE, for example, in response to a transmission of the PDSCH transmission, then, at block  2908 , the base station  2700  may receive the SB-CSI report from the UE with SB reporting with full resolution. 
       FIG. 30  is a flow chart  3000  of a method for reporting sub-band SB-CSI 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 base station  2700 , as described above, and illustrated in  FIG. 27 , by a processor or processing system, or by any suitable means for carrying out the described functions. 
     At block  3002 , the base station  2700  may transmit a physical downlink shared channel (PDSCH) transmission to a user equipment (UE). The features of block  3002  may be the same as or at least similar to one or more features described herein at least with respect to block  2802  of  FIG. 28 . At block  3004 , the base station  2700  may receive either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission from the UE in response to a transmission of the PDSCH transmission. The features of block  3004  may be the same as or at least similar to one or more features described herein at least with respect to block  2804  of  FIG. 28 . 
     At block  3006 , the base station  2700  may determine whether an ACK transmission has been received from the UE. If the base station  2700  determines that an ACK transmission has been received from the UE, for example, in response to a transmission of the PDSCH transmission, then the method ends. If the base station  2700  determines that an ACK transmission has not be received from the UE, for example, in response to a transmission of the PDSCH transmission, then, at block  3008 , the base station  2700  may receive the SB-CSI report from the UE with SB reporting with full resolution or with SB reporting without full resolution or the base station  2700  may receive a CSI configured report from the UE. 
       FIG. 31  is a flow chart  3100  of a method for reporting SB-CSI 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 base station  2700 , as described above, and illustrated in  FIG. 27 , by a processor or processing system, or by any suitable means for carrying out the described functions. 
     At block  3102 , the base station  2700  may transmit a physical downlink shared channel (PDSCH) transmission to a UE. The features of block  3102  may be the same as or at least similar to one or more features described herein at least with respect to block  2802  of  FIG. 28 . At block  3104 , the base station  2700  may receive either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission from the UE in response to a transmission of the PDSCH transmission. The features of block  3104  may be the same as or at least similar to one or more features described herein at least with respect to block  2804  of  FIG. 28 . At block  3106 , the base station  2700  may receive an SB-CSI report from the UE with either SB reporting with full resolution or with SB reporting without full resolution or the base station  2700  may receive a CSI configured report from the UE. 
       FIG. 32  is a flow chart  3200  of a method for reporting sub-band SB-CSI 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 base station  2700 , as described above, and illustrated in  FIG. 27 , by a processor or processing system, or by any suitable means for carrying out the described functions. 
     At block  3202 , the base station  2700  may transmit a physical downlink shared channel (PDSCH) transmission to a user equipment (UE). The features of block  3202  may be the same as or at least similar to one or more features described herein at least with respect to block  2802  of  FIG. 28 . At block  3204 , the base station  2700  may receive either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission from the UE in response to a transmission of the PDSCH transmission. The features of block  3204  may be the same as or at least similar to one or more features described herein at least with respect to block  2804  of  FIG. 28 . 
     At block  3206 , the base station  2700  may transmit a control message to the UE indicating whether the UE is to transmit an SB-CSI report to the base station with SB reporting with full resolution, whether the UE is to transmit an SB-CSI report to the base station with SB reporting without full resolution, or whether the UE is to transmit a CSI configured report. In some aspects, the control message may include at least one of a radio resource control (RRC) message, a medium access control (MAC) control element (MAC-CE), or a downlink control information (DCI). At block  3208 , the base station  2700  may determine whether an ACK transmission has been received from the UE. If the base station  2700  determines that an ACK transmission has been received from the UE, for example, in response to a transmission of the PDSCH transmission, then the method ends. If the base station  2700  determines that an ACK transmission has not be received from the UE, for example, in response to a transmission of the PDSCH transmission, then, at block  3210 , the base station  2700  may receive the SB-CSI report from the UE with SB reporting with full resolution or with SB reporting without full resolution or the base station  2700  may receive a CSI configured report from the UE. 
       FIG. 33  is a flow chart  3300  of a method for reporting SB-CSI 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 base station  2700 , as described above, and illustrated in  FIG. 27 , by a processor or processing system, or by any suitable means for carrying out the described functions. 
     At block  3302 , the base station  2700  may transmit downlink control information (DCI) associated with a PDSCH transmission and indicating a first modulation code scheme (MCS) value associated with the PDSCH transmission. At block  3304 , the base station  2700  may transmit a physical downlink shared channel (PDSCH) transmission to a user equipment (UE). The features of block  3304  may be the same as or at least similar to one or more features described herein at least with respect to block  2802  of  FIG. 28 . At block  3306 , the base station  2700  may receive either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission from the UE in response to a transmission of the PDSCH transmission. The features of block  3306  may be the same as or at least similar to one or more features described herein at least with respect to block  2804  of  FIG. 28 . 
     At block  3308 , the base station  2700  may determine whether an ACK transmission has been received from the UE. If the base station  2700  determines that an ACK transmission has been received from the UE, for example, in response to a transmission of the PDSCH transmission, then the method ends. If the base station  2700  determines that an ACK transmission has not be received from the UE, for example, in response to a transmission of the PDSCH transmission, then, at block  3310 , the base station  2700  may receive the SB-CSI report from the UE with either SB reporting with full resolution or with SB reporting without full resolution or the base station  2700  may receive a CSI configured report from the UE. 
       FIG. 34  is a flow chart  3400  of a method for reporting SB-CSI 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 base station  2700 , as described above, and illustrated in  FIG. 27 , by a processor or processing system, or by any suitable means for carrying out the described functions. 
     At block  3402 , the base station  2700  may transmit a physical downlink shared channel (PDSCH) transmission to a UE. The features of block  3402  may be the same as or at least similar to one or more features described herein at least with respect to block  2802  of  FIG. 28 . At block  3404 , the base station  2700  may receive either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission from the UE in response to a transmission of the PDSCH transmission. The features of block  3204  may be the same as or at least similar to one or more features described herein at least with respect to block  2804  of  FIG. 28 . At block  3406 , the base station  2700  may receive an SB-CSI report with a rank indication (RI) from the UE based on whether the ACK transmission is received from the UE or whether the NACK transmission is received from the UE. 
       FIG. 35  is a flow chart  2900  of a method for reporting SB-CSI 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 base station  2700 , as described above, and illustrated in  FIG. 27 , by a processor or processing system, or by any suitable means for carrying out the described functions. 
     At block  3502 , the base station  2700  may transmit a physical downlink shared channel (PDSCH) transmission to a UE. The features of block  3502  may be the same as or at least similar to one or more features described herein at least with respect to block  2802  of  FIG. 28 . At block  3504 , the base station  2700  may receive either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission from the UE in response to a transmission of the PDSCH transmission. The features of block  3504  may be the same as or at least similar to one or more features described herein at least with respect to block  2804  of  FIG. 28 . 
     At block  3506 , the base station  2700  may determine whether an ACK transmission has been received from the UE. If the base station  2700  determines that an ACK transmission has been received from the UE, for example, in response to a transmission of the PDSCH transmission, then the method ends. If the base station  2700  determines that an ACK transmission has not be received from the UE, for example, in response to a transmission of the PDSCH transmission, then, at block  3508 , the base station  2700  may receive the SB-CSI report from the UE with SB reporting with full resolution and SB rank indication. 
       FIG. 36  is a flow chart  3600  of a method for reporting sub-band SB-CSI 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 base station  2700 , as described above, and illustrated in  FIG. 27 , by a processor or processing system, or by any suitable means for carrying out the described functions. 
     At block  3602 , the base station  2700  may transmit a physical downlink shared channel (PDSCH) transmission to a user equipment (UE). The features of block  3602  may be the same as or at least similar to one or more features described herein at least with respect to block  2802  of  FIG. 28 . At block  3604 , the base station  2700  may receive either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission from the UE in response to a transmission of the PDSCH transmission. The features of block  3604  may be the same as or at least similar to one or more features described herein at least with respect to block  2804  of  FIG. 28 . 
     At block  3606 , the base station  2700  may determine whether an ACK transmission has been received from the UE. If the base station  2700  determines that an ACK transmission has been received from the UE, for example, in response to a transmission of the PDSCH transmission, then the method ends. If the base station  2700  determines that an ACK transmission has not be received from the UE, for example, in response to a transmission of the PDSCH transmission, then, at block  3608 , the base station  2700  may receive the SB-CSI report from the UE as a CSI configure report, an SB-CSI report with full resolution and an RI, or as an SB-CSI report with full resolution and without an RI. 
       FIG. 37  is a flow chart  3700  of a method for reporting SB-CSI 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 base station  2700 , as described above, and illustrated in  FIG. 27 , by a processor or processing system, or by any suitable means for carrying out the described functions. 
     At block  3702 , the base station  2700  may transmit downlink control information (DCI) associated with a PDSCH transmission and indicating a first modulation code scheme (MCS) value associated with the PDSCH transmission. The features of block  3702  may be the same as or at least similar to one or more features described herein at least with respect to block  3302  of  FIG. 33 . At block  3704 , the base station  2700  may transmit a physical downlink shared channel (PDSCH) transmission to a UE. The features of block  3704  may be the same as or at least similar to one or more features described herein at least with respect to block  2802  of  FIG. 28 . At block  3706 , the base station  2700  may receive either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission from the UE in response to a transmission of the PDSCH transmission. The features of block  3706  may be the same as or at least similar to one or more features described herein at least with respect to block  2804  of  FIG. 28 . 
     At block  3708 , the base station  2700  may determine whether an ACK transmission has been received from the UE. If the base station  2700  determines that an ACK transmission has been received from the UE, for example, in response to a transmission of the PDSCH transmission, then the method ends. If the base station  2700  determines that an ACK transmission has not be received from the UE, for example, in response to a transmission of the PDSCH transmission, then, at block  3710 , the base station  2700  may receive the SB-CSI report from the UE as a CSI configure report, an SB-CSI report with full resolution and an RI, or as an SB-CSI report with full resolution and without an RI. 
     In one configuration, the base station  2700  includes means for performing the various functions and processes described in relation to  FIGS. 28, 29, 30, 31, 32, 33, 34, 35, 36, and 37 . In one aspect, the aforementioned means may be the processor  2704  shown in  FIG. 27  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  2704  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  2706 , or any other suitable apparatus or means described in any one of the  FIGS. 1-4 and 7  and utilizing, for example, the processes and/or algorithms described herein in relation to  FIGS. 28, 29, 30, 31, 32, 33, 34, 35, 36, and 37 . 
     In a first aspect, a wireless communication device (e.g., a UE) may receive a physical downlink shared channel (PDSCH) transmission from a base station. The wireless communication device may also transmit either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission to the base station in response to a reception of the PDSCH transmission. The wireless communication device may further determine whether to transmit a sub-band (SB) channel state information (SB-CSI) report to the base station based on whether the ACK transmission is transmitted to the base station or whether the NACK transmission is transmitted to the base station. 
     In a second aspect, alone or in combination with the first aspect, the wireless communication device transmitting either the ACK transmission or the NACK transmission to the base station in response to the reception of the PDSCH transmission may include transmitting either the ACK transmission or the NACK transmission to the base station based on an ability of the UE to decode the PDSCH transmission. 
     In a third aspect, alone or in combination with one or more of the first and second aspects, the wireless communication device may receive downlink control information (DCI) associated with the PDSCH transmission, where the DCI indicates a first modulation coding scheme (MCS) value associated the PDSCH transmission. The wireless communication device may also configure the reception of the DCI for receiving the PDSCH transmission and measure a second MCS value associated with the received PDSCH transmission. 
     In a fourth aspect, alone or in combination with one or more of the first through third aspects, the wireless communication device transmitting either the ACK transmission or the NACK transmission to the base station in response to the reception of the PDSCH transmission may include transmitting either the ACK transmission or the NACK transmission to the base station based on a threshold difference between the first MCS value and the second MCS value. 
     In a fifth aspect, alone or in combination with one or more of the first through fourth aspects, the wireless communication device may transmit the SB-CSI report to the base station when the ACK transmission is transmitted to the base station and transmit the SB-CSI report to the base station when the NACK transmission is transmitted to the base station. 
     In a sixth aspect, alone or in combination with one or more of the first through fifth aspects, the wireless communication device may transmit the SB-CSI report to the base station when the NACK transmission is transmitted to the base station or abstain from transmitting the SB-CSI report when the ACK transmission is transmitted to the base station. 
     In a seventh aspect, alone or in combination with one or more of the first through sixth aspects, when determining to transmit the SB-CSI report to the base station, at least one of the ACK transmission or the NACK transmission includes an indication that the SB-CSI report is to be transmitted to the base station. 
     In an eighth aspect, alone or in combination with one or more of the first through seventh aspects, when determining to transmit the SB-CSI report to the base station, the wireless communication device determines whether to transmit the SB-CSI report including SB reporting with full resolution to the base station, where the SB-CSI report including SB reporting with full resolution includes one or more channel quality information (CQI) values each associated with a sub-band of a plurality of sub-bands utilized by the PDSCH transmission or transmit the SB-CSI report including SB reporting without full resolution including one or more spatial differential CQI values each associated with an offset level, where the offset level comprises a difference between a CQI value associated with a sub-band of the plurality of sub-bands utilized by the PDSCH transmission and an average CQI value associated with the plurality of sub-bands utilized by the PDSCH transmission. 
     In a ninth aspect, alone or in combination with one or more of the first through eighth aspects, the one or more CQI values include at least one of a CQI index, a modulation scheme, a code rate, or an efficiency. 
     In a tenth aspect, alone or in combination with one or more of the first through ninth aspects, determining whether to transmit the SB-CSI report including SB reporting with full resolution to the base station or transmit the SB-CSI report including SB reporting without full resolution including one or more spatial differential CQI values each associated with an offset level is based on at least a quality of a decoding of the PDSCH transmission. 
     In an eleventh aspect, alone or in combination with one or more of the first through tenth aspects, the wireless communication device receives a control message from the base station indicating whether to transmit the SB-CSI report including SB reporting with full resolution to the base station or whether to transmit the SB-CSI report including SB reporting without full resolution. Determining whether to transmit the SB-CSI report including SB reporting with full resolution to the base station or transmit the SB-CSI report including SB reporting without full resolution including one or more spatial differential CQI values each associated with an offset level is based at least on the control message. 
     In a twelfth aspect, alone or in combination with one or more of the first through eleventh aspects, the control message includes at least one of a radio resource control (RRC) message, a medium access control (MAC) control element (MAC-CE), or a downlink control information (DCI). 
     In a thirteenth aspect, alone or in combination with one or more of the first through twelfth aspects, when determining to transmit the SB-CSI report including SB reporting with full resolution to the base station, the wireless communication device determines whether to include a rank indication per sub-band with the SB-CSI report including SB reporting with full resolution for reception by the base station, where the rank indication per sub-band indicates a quantity of sub-bands utilized by the PDSCH transmission that are able to be supported by the UE. 
     In a fourteenth aspect, alone or in combination with one or more of the first through thirteenth aspects, at least one of the ACK transmission or the NACK transmission includes an indication that the rank indication is to be included with the SB-CSI report including SB reporting with full resolution. 
     In a fifteenth aspect, alone or in combination with one or more of the first through fourteenth aspects, the wireless communication device receiving downlink control information (DCI) associated with the PDSCH transmission, where the DCI indicates a first modulation coding scheme (MCS) value associated with the PDSCH transmission. The wireless communication device also configures the reception of the DCI for receiving the PDSCH transmission and measures a second MCS value associated with the received PDSCH transmission. 
     In a sixteenth aspect, alone or in combination with one or more of the first through fifteenth aspects, determining whether to include the rank indication per sub-band with the SB-CSI report with full resolution for reception by the base station is based on a threshold difference between the first MCS value and the second MCS value. 
     In a seventeenth aspect, a base station may transmit a physical downlink shared channel (PDSCH) transmission to a user equipment (UE). The base station may also receive either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission from the UE in response to the transmission of the PDSCH transmission. The base station may further receive a sub-band (SB) channel state information (SB-CSI) report from the UE based on whether the ACK transmission is transmitted by the UE or the NACK transmission is transmitted by the UE. 
     In an eighteenth aspect, alone or in combination with the seventeenth aspect, receiving either the ACK transmission or the NACK transmission from the UE in response to the transmission of the PDSCH transmission includes receiving either the ACK transmission or the NACK transmission from the UE based on an ability of the UE to decode the PDSCH transmission. 
     In a nineteenth aspect, alone or in combination with one or more of the seventeenth through eighteenth aspects, the base station transmits downlink control information (DCI) associated with the PDSCH transmission, where the DCI indicates a first modulation coding scheme (MCS) value associated with the PDSCH transmission. 
     In a twentieth aspect, alone or in combination with one or more of the seventeenth through nineteenth aspects, receiving either the ACK transmission or the NACK transmission from the UE in response to the transmission of the PDSCH transmission includes receiving either the ACK transmission or the NACK transmission from the UE based on a threshold difference between the first MCS value and a second measured MCS value associated with the PDSCH transmission. 
     In a twenty-first aspect, alone or in combination with one or more of the seventeenth through twentieth aspects, the base station receives the SB-CSI report from the UE when the ACK transmission is received from the UE and receives the SB-CSI report from the UE when the NACK transmission is received from the UE. 
     In a twenty-second aspect, alone or in combination with one or more of the seventeenth through twenty-first aspects, the base station receives the SB-CSI report from the UE when the NACK transmission is received from the UE or determines that the SB-CSI report is not received from the UE when the ACK transmission is received from the UE. 
     In a twenty-third aspect, alone or in combination with one or more of the seventeenth through twenty-second aspects, when receiving the SB-CSI report from the UE, at least one of the ACK transmission or the NACK transmission includes an indication that the SB-CSI report is to be received from the UE. 
     In a twenty-fourth aspect, alone or in combination with one or more of the seventeenth through twenty-third aspects, the SB-CSI report comprises one of an SB-CSI report including SB reporting with full resolution, where the SB-CSI report with full resolution includes one or more channel quality information (CQI) values each associated with a sub-band of a plurality of sub-bands utilized by the PDSCH transmission or an SB-CSI report including SB reporting without full resolution including one or more spatial differential CQI values each associated with an offset level, where the offset level comprises a difference between a CQI value associated with a sub-band of the plurality of sub-bands utilized by the PDSCH transmission and an average CQI value associated with the plurality of sub-bands utilized by the PDSCH transmission. 
     In a twenty-fifth aspect, alone or in combination with one or more of the seventeenth through twenty-fourth aspects, the one or more CQI values comprise at least one of a CQI index, a modulation scheme, a code rate, or an efficiency. 
     In a twenty-sixth aspect, alone or in combination with one or more of the seventeenth through twenty-fifth aspects, the SB-CSI report including either the SB reporting with full resolution or the SB reporting without full resolution is based on at least a quality of a decoding of the PDSCH transmission by the UE. 
     In a twenty-seventh aspect, alone or in combination with one or more of the seventeenth through twenty-sixth aspects, the base station transmits a control message to the UE indicating whether the UE is to transmit the SB-CSI report including SB reporting with full resolution or whether to the UE is to transmit the SB-CSI report including SB reporting without full resolution. Receiving either the SB-CSI report including either SB reporting with full resolution or SB reporting without full resolution is based on at least the control message. 
     In a twenty-eighth aspect, alone or in combination with one or more of the seventeenth through twenty-seventh aspects, the control message includes at least one of a radio resource control (RRC) message, a medium access control (MAC) control element (MAC-CE), or a downlink control information (DCI). 
     In a twenty-ninth aspect, alone or in combination with one or more of the seventeenth through twenty-eighth aspects, the SB-CSI report including SB reporting with full resolution includes a rank indication per sub-band indicating a quantity of sub-bands utilized by the PDSCH transmission that are able to be supported by the UE. 
     In a thirtieth aspect, alone or in combination with one or more of the seventeenth through twenty-ninth aspects, when the SB-CSI report including SB reporting with full resolution includes the rank indication per sub-band, at least one of the ACK transmission or the NACK transmission includes an indication that the rank indication is to be included with the SB-CSI report including SB reporting with full resolution. 
     In a thirty-first aspect, alone or in combination with one or more of the seventeenth through thirtieth aspects, the base station transmits downlink control information (DCI) associated with the PDSCH transmission, where the DCI includes a first modulation coding scheme (MCS) value associated with the PDSCH transmission. 
     In a thirty-second aspect, alone or in combination with one or more of the seventeenth through thirty-first aspects, the SB-CSI report including SB reporting with full resolution includes the rank indication per sub-band based on a threshold difference between the first MCS value and a second measured MCS value associated with the PDSCH transmission. 
     In one configuration, a wireless communication device includes means for receiving a physical downlink shared channel (PDSCH) transmission from a base station, means for transmitting either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission to the base station in response to a reception of the PDSCH transmission, and means for determining whether to transmit a sub-band (SB) channel state information (SB-CSI) report to the base station based on whether the ACK transmission is transmitted to the base station or whether the NACK transmission is transmitted to the base station. 
     In one aspect, the aforementioned means for receiving a physical downlink shared channel (PDSCH) transmission from a base station, means for transmitting either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission to the base station in response to a reception of the PDSCH transmission, and means for determining whether to transmit a sub-band (SB) channel state information (SB-CSI) report to the base station based on whether the ACK transmission is transmitted to the base station or whether the NACK transmission is transmitted to the base station may be the processor(s)  1404  shown in  FIG. 14  configured to perform the functions recited by the aforementioned means. For example, the aforementioned means for receiving a physical downlink shared channel (PDSCH) transmission from a base station may include the receiving circuitry  1440  and transceiver  1410  in  FIG. 14 . As another example, the aforementioned means for transmitting either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission to the base station in response to a reception of the PDSCH transmission may include the transmitting circuitry  1442  and transceiver  1410  shown in  FIG. 14 . As yet another example, the aforementioned means for determining whether to transmit a sub-band (SB) channel state information (SB-CSI) report to the base station based on whether the ACK transmission is transmitted to the base station or whether the NACK transmission is transmitted to the base station may include the determining circuitry  1444  shown in  FIG. 14 . In another aspect, the aforementioned means may be a circuit or any apparatus configured to perform the functions recited by the aforementioned means. 
     In one configuration, a base station includes means for transmitting a physical downlink shared channel (PDSCH) transmission to a user equipment (UE), means for receiving either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission from the UE in response to the transmission of the PDSCH transmission, and means for receiving a sub-band (SB) channel state information (SB-CSI) report from the UE based on whether the ACK transmission is transmitted by the UE or the NACK transmission is transmitted by the UE. 
     In one aspect, the aforementioned means for transmitting a physical downlink shared channel (PDSCH) transmission to a user equipment (UE), means for receiving either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission from the UE in response to the transmission of the PDSCH transmission, and means for receiving a sub-band (SB) channel state information (SB-CSI) report from the UE based on whether the ACK transmission is transmitted by the UE or the NACK transmission is transmitted by the UE may be the processor(s)  2704  shown in  FIG. 27  configured to perform the functions recited by the aforementioned means. For example, the aforementioned means for transmitting a physical downlink shared channel (PDSCH) transmission to a user equipment (UE) may include the transmitting circuitry  2740  and transceiver  2710  shown in  FIG. 27 . As another example, the aforementioned means for receiving either an acknowledgement (ACK) transmission or a negative acknowledgement (NACK) transmission from the UE in response to the transmission of the PDSCH transmission may include the receiving circuitry  2742  and transceiver  2710  shown in  FIG. 27 . As another example, the aforementioned means for receiving a sub-band (SB) channel state information (SB-CSI) report from the UE based on whether the ACK transmission is transmitted by the UE or the NACK transmission is transmitted by the UE may include the receiving circuitry  2742  and transceiver  2710  shown in  FIG. 27 . In another aspect, the aforementioned means may be a circuit or any apparatus configured to perform the functions recited by the aforementioned means. 
     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. 1-37  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. 1-37  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, where 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.