Patent Publication Number: US-2023155653-A1

Title: Channel state information reporting for partial bands

Description:
CROSS REFERENCE 
     The present application is a 371 national stage filing of International PCT Application No. PCT/CN2020/089602 by HAO et al. entitled “CHANNEL STATE INFORMATION REPORTING FOR PARTIAL BANDS,” filed May 11, 2020, which is assigned to the assignee hereof, and which is expressly incorporated by reference in its entirety herein. 
    
    
     FIELD OF TECHNOLOGY 
     The following relates generally to wireless communications and more specifically to channel state information reporting for partial bands. 
     BACKGROUND 
     Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include fourth generation (4G) systems such as Long Term Evolution (LTE) systems, LTE-Advanced (LTE-A) systems, or LTE-A Pro systems, and fifth generation (5G) systems which may be referred to as New Radio (NR) systems. These systems may employ technologies such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiple access (OFDMA), or discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM). A wireless multiple-access communications system may include one or more base stations or one or more network access nodes, each simultaneously supporting communication for multiple communication devices, which may be otherwise known as user equipment (UE). 
     A base station may configure a UE for uplink or downlink communications. However, the base station may configure the UE poorly based on feedback that is reported by the UE. 
     SUMMARY 
     The described techniques relate to improved methods, systems, devices, and apparatuses that support channel state information reporting for partial bands. Generally, the described techniques provide for improving the granularity and quality of channel state information (CSI). For example, a user equipment (UE) may provide CSI to a base station on a per-partial band basis, and the base station may configure the UE based on the CSI. 
     A UE may receive a configuration message from a base station, and the configuration message may include an indication of one or more partial bands for CSI reporting. Each partial band of the one or more partial bands may be less than a system bandwidth and include a plurality of frequency domain units (e.g., subbands, resource blocks, etc.) associated with a precoder. The UE may select one or more antenna ports (e.g., CSI reference signal (CSI-RS) ports) for each partial band of the one or more partial bands based on the configuration message. For example, the configuration message may indicate a group of antenna ports, a number of antenna ports, a minimum number of antenna ports, or a maximum number of antenna ports, and the UE may select the one or more antenna ports based on the configuration message. The UE may calculate CSI including a linear combination of the selected one or more antenna ports for each partial band. The CSI may be calculated based on receiving the configuration message, and the UE may transmit the CSI to a base station. The CSI may include an indication of the selected antenna ports and linear combination coefficients for each partial band of the one or more partial bands. 
     A method of wireless communication at a UE is described. The method may include receiving from a base station a configuration message including an indication of one or more partial bands for channel state information reporting, where each partial band of the one or more partial bands is less than a system bandwidth and includes a set of frequency domain units associated with a precoder, selecting one or more antenna ports for each partial band of the one or more partial bands based on the configuration message, calculating channel state information including a linear combination of the selected one or more antenna ports for each partial band, based on receiving the configuration message, and transmitting the channel state information including at least an indication of the selected antenna ports and linear combination coefficients for each partial band of the one or more partial bands. 
     An apparatus for wireless communication at a UE is described. The apparatus may include a processor, memory coupled with the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to receive from a base station a configuration message including an indication of one or more partial bands for channel state information reporting, where each partial band of the one or more partial bands is less than a system bandwidth and includes a set of frequency domain units associated with a precoder, select one or more antenna ports for each partial band of the one or more partial bands based on the configuration message, calculate channel state information including a linear combination of the selected one or more antenna ports for each partial band, based on receiving the configuration message, and transmit the channel state information including at least an indication of the selected antenna ports and linear combination coefficients for each partial band of the one or more partial bands. 
     Another apparatus for wireless communication at a UE is described. The apparatus may include means for receiving from a base station a configuration message including an indication of one or more partial bands for channel state information reporting, where each partial band of the one or more partial bands is less than a system bandwidth and includes a set of frequency domain units associated with a precoder, selecting one or more antenna ports for each partial band of the one or more partial bands based on the configuration message, calculating channel state information including a linear combination of the selected one or more antenna ports for each partial band, based on receiving the configuration message, and transmitting the channel state information including at least an indication of the selected antenna ports and linear combination coefficients for each partial band of the one or more partial bands. 
     A non-transitory computer-readable medium storing code for wireless communication at a UE is described. The code may include instructions executable by a processor to receive from a base station a configuration message including an indication of one or more partial bands for channel state information reporting, where each partial band of the one or more partial bands is less than a system bandwidth and includes a set of frequency domain units associated with a precoder, select one or more antenna ports for each partial band of the one or more partial bands based on the configuration message, calculate channel state information including a linear combination of the selected one or more antenna ports for each partial band, based on receiving the configuration message, and transmit the channel state information including at least an indication of the selected antenna ports and linear combination coefficients for each partial band of the one or more partial bands. 
     In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, selecting the one or more antenna ports may include operations, features, means, or instructions for selecting a subset of a total number of antenna ports for each partial band of the one or more partial bands. 
     In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, a same subset of one or more CSI-RS ports may be selected for each partial band of the one or more partial bands. 
     Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for calculating the channel state information includes separately precoding each partial band of the one or more partial bands. 
     In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the indication of one or more partial bands for channel state reporting includes one or more of a numerical quantity of partial bands for which the UE may be to perform channel state measurement, or a partial band size for which the UE may be to perform channel state measurement, or a ratio of partial band size to frequency domain unit size. 
     Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for transmitting to the base station a capability message indicating a numerical quality of partial bands for which the UE may be capable of performing channel measurement, where the configuration message may be based on the capability message. 
     In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the indication of one or more partial bands may be dependent on an indication of a numerical quantity of antenna ports to select for each partial band of the one or more partial bands, or a numerical quantity of total antenna ports, and selecting the one or more antenna ports for each partial band may be based on the indicated numerical quantity. 
     In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the antenna ports include channel state information reference signal (CSI-RS) ports and the configuration message further includes a joint indication of partial bands and a numerical quantity of the CSI-RS ports, and selecting the one or more antenna ports for each partial band may be based on the joint indication. 
     In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the joint indication may include operations, features, means, or instructions for a number of partial bands, a partial band size, or a ratio of partial bands to frequency unit size; and one or more of: a number of total CSI-RS ports or a number of CSI-RS ports to be selected for each partial band. 
     Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for transmitting to the base station a report of the one or more antenna ports selected for each partial band of the one or more partial bands, where the report of the one or more antenna ports selected for each partial band includes an indication of a first set of antenna ports common to all partial bands of the one or more partial bands and, for each partial band of the one or more partial bands, an indication of a second set of antenna ports independently selected for that partial band, where the second set of antenna ports for each partial band may be from the first set of antenna ports. 
     Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for receiving from the base station a configuration of a size of the first set of antenna ports and a size of the second set of antenna ports. 
     Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for transmitting to the base station a report of a resource selection for the channel state measurement for each partial band of the one or more partial bands. 
     Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for receiving, from the base station, a configuration of frequency domain restriction for channel measurement, and determining that a frequency domain restriction for channel measurement may be in place based on the configuration of frequency domain restriction for channel measurement, where calculating the channel information for each partial band of the one or more partial bands includes restricting the channel state measurement to non-zero power channel state information reference signals within each partial band. 
     Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for receiving, from the base station, a configuration of frequency domain restriction for interference measurement, and determining that a frequency domain restriction for interference measurement may be in place based on the configuration of frequency domain restriction for channel measurement, where performing interference measurement for each partial band of the one or more partial bands includes restricting the interference measurement to zero or non-zero interference measurement resources within each partial band. 
     In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, a frequency domain unit of the set of frequency domain units corresponds to a subband size for channel quality indicator (CQI) reporting. 
     A method of wireless communication at a base station including is described. The method may include transmitting to a UE a configuration message including an indication of one or more partial bands for channel state information reporting, where each partial band of the one or more partial bands is less than a system bandwidth and includes a set of frequency domain units associated with a precoder, receiving channel state information including an indication of antenna ports and linear combination coefficients for each partial band of the one or more partial bands based on transmitting the configuration message and the channel state measurement, and communicating with the UE based on receiving the channel state information for each partial band of the one or more partial bands. 
     An apparatus for wireless communication at a base station including is described. The apparatus may include a processor, memory coupled with the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to transmit to a UE a configuration message including an indication of one or more partial bands for channel state information reporting, where each partial band of the one or more partial bands is less than a system bandwidth and includes a set of frequency domain units associated with a precoder, receive channel state information including an indication of antenna ports and linear combination coefficients for each partial band of the one or more partial bands based on transmitting the configuration message and the channel state measurement, and communicate with the UE based on receiving the channel state information for each partial band of the one or more partial bands. 
     Another apparatus for wireless communication at a base station including is described. The apparatus may include means for transmitting to a UE a configuration message including an indication of one or more partial bands for channel state information reporting, where each partial band of the one or more partial bands is less than a system bandwidth and includes a set of frequency domain units associated with a precoder, receiving channel state information including an indication of antenna ports and linear combination coefficients for each partial band of the one or more partial bands based on transmitting the configuration message and the channel state measurement, and communicating with the UE based on receiving the channel state information for each partial band of the one or more partial bands. 
     A non-transitory computer-readable medium storing code for wireless communication at a base station including is described. The code may include instructions executable by a processor to transmit to a UE a configuration message including an indication of one or more partial bands for channel state information reporting, where each partial band of the one or more partial bands is less than a system bandwidth and includes a set of frequency domain units associated with a precoder, receive channel state information including an indication of antenna ports and linear combination coefficients for each partial band of the one or more partial bands based on transmitting the configuration message and the channel state measurement, and communicate with the UE based on receiving the channel state information for each partial band of the one or more partial bands. 
     In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the indication of one or more partial bands for channel state reporting includes one or more of a numerical quantity of partial bands for which the UE may be to perform channel state measurement, or a partial band size for which the UE may be to perform channel state measurement, or a ratio of partial band size to frequency domain unit size. 
     In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the indication of one or more partial bands may be dependent on an indication of a numerical quantity of antenna ports to select for each partial band of the one or more partial bands, or a numerical quantity of total antenna ports, and selecting the one or more antenna ports for each partial band may be based on the indicated numerical quantity. 
     Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for receiving a capability message from the UE indicating a numerical quality of partial bands for which the UE may be capable of performing channel measurement, where the configuration message may be based on the capability message. 
     In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the antenna ports include channel state information reference signal (CSI-RS) ports and the configuration message further includes a joint indication of partial bands and a numerical quantity of the CSI-RS ports, and the one or more antenna ports for each partial band may be selected based on the join indication. 
     In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the joint indication may include operations, features, means, or instructions for a number of partial bands, a partial band size, or a ratio of partial bands to frequency unit size; and one or more of: a number of total CSI-RS ports or a number of CSI-RS ports to be selected for each partial band. 
     Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for receiving a report from the UE of one or more antenna ports selected for each partial band of the one or more partial bands, where the report of the one or more antenna ports selected for each partial band includes an indication of a first set of antenna ports common to all partial bands of the one or more partial bands and, for each partial band of the one or more partial bands, an indication of a second set of antenna ports independently selected for that partial band, where the second set of antenna ports for each partial band may be from the first set of antenna ports. 
     Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for transmitting to the UE a configuration of a size of the first set of antenna ports and a size of the second set of antenna ports. 
     Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for receiving from the UE a report of a resource selection for the channel state measurement for each partial band of the one or more partial bands. 
     Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for transmitting, to the UE, a configuration of frequency domain restriction for channel measurement, and receiving the channel state information based on channel measurement of non-zero power channel state information reference signals within each partial band. 
     Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for transmitting, to the UE, a configuration of frequency domain restriction for interference measurement, and receiving the channel state information based on interference measurement of interference measurement resources within each partial band. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    illustrates an example of a system for wireless communications that supports channel state information reporting for partial bands in accordance with aspects of the present disclosure. 
         FIG.  2    illustrates an example of a wireless communications system that supports channel state information reporting for partial bands in accordance with aspects of the present disclosure. 
         FIG.  3    illustrates an example of a channel state information reporting technique that supports channel state information reporting for partial bands in accordance with aspects of the present disclosure. 
         FIG.  4    illustrates an example of a process flow that supports channel state information reporting for partial bands in accordance with aspects of the present disclosure. 
         FIGS.  5  and  6    show block diagrams of devices that support channel state information reporting for partial bands in accordance with aspects of the present disclosure. 
         FIG.  7    shows a block diagram of a channel state information manager that supports channel state information reporting for partial bands in accordance with aspects of the present disclosure. 
         FIG.  8    shows a diagram of a system including a device that supports channel state information reporting for partial bands in accordance with aspects of the present disclosure. 
         FIGS.  9  and  10    show block diagrams of devices that support channel state information reporting for partial bands in accordance with aspects of the present disclosure. 
         FIG.  11    shows a block diagram of a channel state information manager that supports channel state information reporting for partial bands in accordance with aspects of the present disclosure. 
         FIG.  12    shows a diagram of a system including a device that supports channel state information reporting for partial bands in accordance with aspects of the present disclosure. 
         FIGS.  13  through  16    show flowcharts illustrating methods that support channel state information reporting for partial bands in accordance with aspects of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may support a user equipment (UE) receiving a channel state information reference signal (CSI-RS), measuring the CSI-RS transmission, and sending channel information (e.g., channel state information, a CSI report, etc.) to the base station. In some cases, the CSI-RS may be precoded, and the precoding of the CSI-RS may be based on spatial and delay reciprocity between uplink and downlink channels, but portions of the system bandwidth used to transmit the CSI-RS may have poor spatial and delay reciprocity across the uplink and downlink channels. In some cases, providing a channel report for the system bandwidth with poor spatial reciprocity may lower the quality of the channel as indicated in the channel report. A base station may set a low modulation and coding scheme (MCS) for the system bandwidth based on the low channel quality indicated in the channel report, which may negatively affect throughput between the UE and the base station. 
     In some cases, a UE may receive a CSI-RS with frequency selective precoding. The precoded CSI-RS may be received across all FD units (e.g., FD unit 0, FD unit 1, . . . FD N 3 −1), as shown in table 1. The precoder of a CSI-RS port may be formed by a pair of a spatial domain (SD) basis (e.g., an SD transmission filter) and an FD basis (e.g., FD transmission filter/weight). The UE may calculate CSI based on an observation for a port “p” on FD unit “n”. For example, the UE may observe Ĥ p [n]=Hb i(p) f m(p)   H [n] for port “p” on FD unit “n”, where “H” is the wireless channel between the UE and a base station without precoding. For each layer, the UE may select a subset of total ports and report a single coefficient per port across the frequency band. In some cases, the UE may report CSI for all FD units as a linear combination of the selected ports. The precoding matrix indicator (PMI) for a certain layer l on any of the N 3  FD units may be expressed by W l =Σ k     0     −1   k=0 v i     k(l)   *C k,l  where v i     k(l)    is the size of P×1 with only one “1” in row i k  indicating port i k(l)  is selected for layer l, P is the total number of CSI-RS ports, and C k,l  is a linear combination coefficient. In some cases, the UE may calculate a channel quality indicator (CQI) using a virtual physical downlink shared channel (PDSCH) as expressed by 
     
       
         
           
             
               
                 [ 
                 
                   
                     
                       
                         y 
                         3000 
                       
                     
                   
                   
                     
                       … 
                     
                   
                   
                     
                       
                         y 
                         
                           3000 
                           + 
                           P 
                           - 
                           1 
                         
                       
                     
                   
                 
                 ] 
               
               = 
               
                 W 
                 [ 
                 
                   
                     
                       
                         x 
                         0 
                       
                     
                   
                   
                     
                       … 
                     
                   
                   
                     
                       
                         x 
                         
                           ( 
                           
                             v 
                             - 
                             1 
                           
                           ) 
                         
                       
                     
                   
                 
                 ] 
               
             
             , 
           
         
       
     
     and the actual precoder of the virtual PDSCH may be expressed by [b (3000) f m(3000)   H , . . . ,b i(3000+P−1) f m(3000+P−1)   H ]×[Σ k     0     −1   k=0 v k(o) *c k,0 , . . . ,Σ k     0     −1   k=0 v i     k(v−1)   *C k,v−1 ,], as illustrated in Table 1. 
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 FD Unit 0 
                 FD Unit 1 
                 FD Unit N 3  − 1 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 Port 3000 
                 b 0  * f 0   H [0] 
                 b 0  * f 0   H [1] 
                 . . . 
                 b 0  * f 0   H [N 3  − 1] 
               
               
                 Port 3001 
                 b 0  * f 1   H [0] 
                 b 0  * f 1   H [1] 
                 . . . 
                 b 0  * f 1   H [N 3  − 1] 
               
               
                 Port 3002 
                 b 1  * f 0   H [0] 
                 b 1  * f 0   H [1] 
                 . . . 
                 b 1  * f 0   H [N 3  − 1] 
               
               
                 Port 3003 
                 b 1  * f 1   H [0] 
                 b 1  * f 1   H [1] 
                 . . . 
                 b 1  * f 1   H [N 3  − 1] 
               
               
                   
               
            
           
         
       
     
     According to aspects described herein, a UE may provide channel information for a number of partial bands associated with a system bandwidth. In some cases, a base station may configure the UE with a set of partial bands for which the UE is to provide channel information (e.g., CSI). The UE may use the set of partial bands to measure a reference signal (e.g., a CSI-RS) transmitted by the base station and provide channel information on a per-partial band basis by transmitting CSI coefficients for each partial band to the base station. In some additional or alternative cases, the base station may configure a set of antenna ports (e.g., CSI-RS ports) for the UE to use in measuring the reference signal (e.g., a CSI-RS) for each partial band. Reporting channel information (e.g., CSI) on a per-partial band basis and/or a number of antenna ports may increase the granularity of the channel information and allow the base station to determine different channel conditions for different partial bands. The base station may use the increased granularity of the channel information to configure the UE, thereby improving system efficiency. 
     In some cases, the base station may configure the UE with a number of partial bands, and the UE may report channel information for the number of partial bands. A partial band width may be smaller than a system bandwidth width and larger than a subband (e.g., frequency domain unit, resource block, etc.) width. The base station may additionally or alternatively configure the UE with a number of ports that may be selected for use in measuring channel information. The base station may configure the UE by transmitting a pair of numbers to the UE, and the pair of number may indicate port and subband information for use in measuring channel information. For example, a first number in the pair of numbers may indicate a CSI-RS port or a number of CSI-RS ports the UE may select, and a second number in the pair of numbers may indicate a number of partial bands. The UE may select a number of CSI-RS ports for each partial band, calculate CSI based on the partial band and/or port information, and transmit the calculated CSI containing linear combination coefficients for each partial band to the base station. 
     The UE may receive a configuration message from a base station, and the configuration message may include an indication of one or more partial bands for CSI reporting. The width of each partial band of the one or more partial bands may be less than the width of a system bandwidth and include a plurality of frequency domain units (e.g., subbands, resource blocks, etc.). The UE may select one or more antenna ports (e.g., CSI-RS ports) for each partial band based on the configuration message and receive a reference signal (e.g., a CSI-RS) at the one or more antenna ports. The UE may calculate CSI that includes a linear combination of the selected one or more antenna ports for each partial band. In some cases, the CSI may be calculated based on receiving the configuration message. The UE may transmit the CSI to a base station, and the CSI may include an indication of the selected antenna ports and linear combination coefficients for each partial band of the one or more partial bands. 
     Aspects of the disclosure are initially described in the context of wireless communications systems. Aspects of the disclosure are also described with respect to an additional wireless communications system, a channel state information reporting technique, and a process flow. Aspects of the disclosure are further illustrated by and described with reference to apparatus diagrams, system diagrams, and flowcharts that relate to channel state information reporting for partial bands. 
       FIG.  1    illustrates an example of a wireless communications system  100  that supports channel state information reporting for partial bands in accordance with aspects of the present disclosure. The wireless communications system  100  may include one or more base stations  105 , one or more UEs  115 , and a core network  130 . In some examples, the wireless communications system  100  may be a Long Term Evolution (LTE) network, an LTE-Advanced (LTE-A) network, an LTE-A Pro network, or a New Radio (NR) network. In some examples, the wireless communications system  100  may support enhanced broadband communications, ultra-reliable (e.g., mission critical) communications, low latency communications, communications with low-cost and low-complexity devices, or any combination thereof. 
     The base stations  105  may be dispersed throughout a geographic area to form the wireless communications system  100  and may be devices in different forms or having different capabilities. The base stations  105  and the UEs  115  may wirelessly communicate via one or more communication links  125 . Each base station  105  may provide a coverage area  110  over which the UEs  115  and the base station  105  may establish one or more communication links  125 . The coverage area  110  may be an example of a geographic area over which a base station  105  and a UE  115  may support the communication of signals according to one or more radio access technologies. 
     The UEs  115  may be dispersed throughout a coverage area  110  of the wireless communications system  100 , and each UE  115  may be stationary, or mobile, or both at different times. The UEs  115  may be devices in different forms or having different capabilities. Some example UEs  115  are illustrated in  FIG.  1   . The UEs  115  described herein may be able to communicate with various types of devices, such as other UEs  115 , the base stations  105 , or network equipment (e.g., core network nodes, relay devices, integrated access and backhaul (IAB) nodes, or other network equipment), as shown in  FIG.  1   . 
     The base stations  105  may communicate with the core network  130 , or with one another, or both. For example, the base stations  105  may interface with the core network  130  through one or more backhaul links  120  (e.g., via an S1, N2, N3, or other interface). The base stations  105  may communicate with one another over the backhaul links  120  (e.g., via an X2, Xn, or other interface) either directly (e.g., directly between base stations  105 ), or indirectly (e.g., via core network  130 ), or both. In some examples, the backhaul links  120  may be or include one or more wireless links. 
     One or more of the base stations  105  described herein may include or may be referred to by a person having ordinary skill in the art as a base transceiver station, a radio base station, an access point, a radio transceiver, a NodeB, an eNodeB (eNB), a next-generation NodeB or a giga-NodeB (either of which may be referred to as a gNB), a Home NodeB, a Home eNodeB, or other suitable terminology. 
     A UE  115  may include or may be referred to as a mobile device, a wireless device, a remote device, a handheld device, or a subscriber device, or some other suitable terminology, where the “device” may also be referred to as a unit, a station, a terminal, or a client, among other examples. A UE  115  may also include or may be referred to as a personal electronic device such as a cellular phone, a personal digital assistant (PDA), a tablet computer, a laptop computer, or a personal computer. In some examples, a UE  115  may include or be referred to as a wireless local loop (WLL) station, an Internet of Things (IoT) device, an Internet of Everything (IoE) device, or a machine type communications (MTC) device, among other examples, which may be implemented in various objects such as appliances, or vehicles, meters, among other examples. 
     The UEs  115  described herein may be able to communicate with various types of devices, such as other UEs  115  that may sometimes act as relays as well as the base stations  105  and the network equipment including macro eNBs or gNBs, small cell eNBs or gNBs, or relay base stations, among other examples, as shown in  FIG.  1   . 
     The UEs  115  and the base stations  105  may wirelessly communicate with one another via one or more communication links  125  over one or more carriers. The term “carrier” may refer to a set of radio frequency spectrum resources having a defined physical layer structure for supporting the communication links  125 . For example, a carrier used for a communication link  125  may include a portion of a radio frequency spectrum band (e.g., a bandwidth part (BWP)) that is operated according to one or more physical layer channels for a given radio access technology (e.g., LTE, LTE-A, LTE-A Pro, NR). Each physical layer channel may carry acquisition signaling (e.g., synchronization signals, system information), control signaling that coordinates operation for the carrier, user data, or other signaling. The wireless communications system  100  may support communication with a UE  115  using carrier aggregation or multi-carrier operation. A UE  115  may be configured with multiple downlink component carriers and one or more uplink component carriers according to a carrier aggregation configuration. Carrier aggregation may be used with both frequency division duplexing (FDD) and time division duplexing (TDD) component carriers. 
     In some examples (e.g., in a carrier aggregation configuration), a carrier may also have acquisition signaling or control signaling that coordinates operations for other carriers. A carrier may be associated with a frequency channel (e.g., an evolved universal mobile telecommunication system terrestrial radio access (E-UTRA) absolute radio frequency channel number (EARFCN)) and may be positioned according to a channel raster for discovery by the UEs  115 . A carrier may be operated in a standalone mode where initial acquisition and connection may be conducted by the UEs  115  via the carrier, or the carrier may be operated in a non-standalone mode where a connection is anchored using a different carrier (e.g., of the same or a different radio access technology). 
     The communication links  125  shown in the wireless communications system  100  may include uplink transmissions from a UE  115  to a base station  105 , or downlink transmissions from a base station  105  to a UE  115 . Carriers may carry downlink or uplink communications (e.g., in an FDD mode) or may be configured to carry downlink and uplink communications (e.g., in a TDD mode). 
     A carrier may be associated with a particular bandwidth of the radio frequency spectrum, and in some examples the carrier bandwidth may be referred to as a “system bandwidth” of the carrier or the wireless communications system  100 . For example, the carrier bandwidth may be one of a number of determined bandwidths for carriers of a particular radio access technology (e.g., 1.4, 3, 5, 10, 15, 20, 40, or 80 megahertz (MHz)). Devices of the wireless communications system  100  (e.g., the base stations  105 , the UEs  115 , or both) may have hardware configurations that support communications over a particular carrier bandwidth or may be configurable to support communications over one of a set of carrier bandwidths. In some examples, the wireless communications system  100  may include base stations  105  or UEs  115  that support simultaneous communications via carriers associated with multiple carrier bandwidths. In some examples, each served UE  115  may be configured for operating over portions (e.g., a sub-band, a BWP) or all of a carrier bandwidth. 
     Signal waveforms transmitted over a carrier may be made up of multiple subcarriers (e.g., using multi-carrier modulation (MCM) techniques such as orthogonal frequency division multiplexing (OFDM) or discrete Fourier transform spread OFDM (DFT-S-OFDM)). In a system employing MCM techniques, a resource element may consist of one symbol period (e.g., a duration of one modulation symbol) and one subcarrier, where the symbol period and subcarrier spacing are inversely related. The number of bits carried by each resource element may depend on the modulation scheme (e.g., the order of the modulation scheme, the coding rate of the modulation scheme, or both). Thus, the more resource elements that a UE  115  receives and the higher the order of the modulation scheme, the higher the data rate may be for the UE  115 . A wireless communications resource may refer to a combination of a radio frequency spectrum resource, a time resource, and a spatial resource (e.g., spatial layers or beams), and the use of multiple spatial layers may further increase the data rate or data integrity for communications with a UE  115 . 
     One or more numerologies for a carrier may be supported, where a numerology may include a subcarrier spacing (Δf) and a cyclic prefix. A carrier may be divided into one or more BWPs having the same or different numerologies. In some examples, a UE  115  may be configured with multiple BWPs. In some examples, a single BWP for a carrier may be active at a given time and communications for the UE  115  may be restricted to one or more active BWPs. 
     The time intervals for the base stations  105  or the UEs  115  may be expressed in multiples of a basic time unit which may, for example, refer to a sampling period of T s =1/(Δf max ·N f ) seconds, where Δf max  may represent the maximum supported subcarrier spacing, and N f  may represent the maximum supported discrete Fourier transform (DFT) size. Time intervals of a communications resource may be organized according to radio frames each having a specified duration (e.g., 10 milliseconds (ms)). Each radio frame may be identified by a system frame number (SFN) (e.g., ranging from 0 to 1023). 
     Each frame may include multiple consecutively numbered subframes or slots, and each subframe or slot may have the same duration. In some examples, a frame may be divided (e.g., in the time domain) into subframes, and each subframe may be further divided into a number of slots. Alternatively, each frame may include a variable number of slots, and the number of slots may depend on subcarrier spacing. Each slot may include a number of symbol periods (e.g., depending on the length of the cyclic prefix prepended to each symbol period). In some wireless communications systems  100 , a slot may further be divided into multiple mini-slots containing one or more symbols. Excluding the cyclic prefix, each symbol period may contain one or more (e.g., N f ) sampling periods. The duration of a symbol period may depend on the subcarrier spacing or frequency band of operation. 
     A subframe, a slot, a mini-slot, or a symbol may be the smallest scheduling unit (e.g., in the time domain) of the wireless communications system  100  and may be referred to as a transmission time interval (TTI). In some examples, the TTI duration (e.g., the number of symbol periods in a TTI) may be variable. Additionally or alternatively, the smallest scheduling unit of the wireless communications system  100  may be dynamically selected (e.g., in bursts of shortened TTIs (sTTIs)). 
     Physical channels may be multiplexed on a carrier according to various techniques. A physical control channel and a physical data channel may be multiplexed on a downlink carrier, for example, using one or more of time division multiplexing (TDM) techniques, frequency division multiplexing (FDM) techniques, or hybrid TDM-FDM techniques. A control region (e.g., a control resource set (CORESET)) for a physical control channel may be defined by a number of symbol periods and may extend across the system bandwidth or a subset of the system bandwidth of the carrier. One or more control regions (e.g., CORESETs) may be configured for a set of the UEs  115 . For example, one or more of the UEs  115  may monitor or search control regions for control information according to one or more search space sets, and each search space set may include one or multiple control channel candidates in one or more aggregation levels arranged in a cascaded manner. An aggregation level for a control channel candidate may refer to a number of control channel resources (e.g., control channel elements (CCEs)) associated with encoded information for a control information format having a given payload size. Search space sets may include common search space sets configured for sending control information to multiple UEs  115  and UE-specific search space sets for sending control information to a specific UE  115 . 
     Each base station  105  may provide communication coverage via one or more cells, for example a macro cell, a small cell, a hot spot, or other types of cells, or any combination thereof. The term “cell” may refer to a logical communication entity used for communication with a base station  105  (e.g., over a carrier) and may be associated with an identifier for distinguishing neighboring cells (e.g., a physical cell identifier (PCID), a virtual cell identifier (VCID), or others). In some examples, a cell may also refer to a geographic coverage area  110  or a portion of a geographic coverage area  110  (e.g., a sector) over which the logical communication entity operates. Such cells may range from smaller areas (e.g., a structure, a subset of structure) to larger areas depending on various factors such as the capabilities of the base station  105 . For example, a cell may be or include a building, a subset of a building, or exterior spaces between or overlapping with geographic coverage areas  110 , among other examples. 
     A macro cell generally covers a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by the UEs  115  with service subscriptions with the network provider supporting the macro cell. A small cell may be associated with a lower-powered base station  105 , as compared with a macro cell, and a small cell may operate in the same or different (e.g., licensed, unlicensed) frequency bands as macro cells. Small cells may provide unrestricted access to the UEs  115  with service subscriptions with the network provider or may provide restricted access to the UEs  115  having an association with the small cell (e.g., the UEs  115  in a closed subscriber group (CSG), the UEs  115  associated with users in a home or office). A base station  105  may support one or multiple cells and may also support communications over the one or more cells using one or multiple component carriers. 
     In some examples, a carrier may support multiple cells, and different cells may be configured according to different protocol types (e.g., MTC, narrowband IoT (NB-IoT), enhanced mobile broadband (eMBB)) that may provide access for different types of devices. 
     In some examples, a base station  105  may be movable and therefore provide communication coverage for a moving geographic coverage area  110 . In some examples, different geographic coverage areas  110  associated with different technologies may overlap, but the different geographic coverage areas  110  may be supported by the same base station  105 . In other examples, the overlapping geographic coverage areas  110  associated with different technologies may be supported by different base stations  105 . The wireless communications system  100  may include, for example, a heterogeneous network in which different types of the base stations  105  provide coverage for various geographic coverage areas  110  using the same or different radio access technologies. 
     The wireless communications system  100  may support synchronous or asynchronous operation. For synchronous operation, the base stations  105  may have similar frame timings, and transmissions from different base stations  105  may be approximately aligned in time. For asynchronous operation, the base stations  105  may have different frame timings, and transmissions from different base stations  105  may, in some examples, not be aligned in time. The techniques described herein may be used for either synchronous or asynchronous operations. 
     Some UEs  115 , such as MTC or IoT devices, may be low cost or low complexity devices and may provide for automated communication between machines (e.g., via Machine-to-Machine (M2M) communication). M2M communication or MTC may refer to data communication technologies that allow devices to communicate with one another or a base station  105  without human intervention. In some examples, M2M communication or MTC may include communications from devices that integrate sensors or meters to measure or capture information and relay such information to a central server or application program that makes use of the information or presents the information to humans interacting with the application program. Some UEs  115  may be designed to collect information or enable automated behavior of machines or other devices. Examples of applications for MTC devices include smart metering, inventory monitoring, water level monitoring, equipment monitoring, healthcare monitoring, wildlife monitoring, weather and geological event monitoring, fleet management and tracking, remote security sensing, physical access control, and transaction-based business charging. 
     Some UEs  115  may be configured to employ operating modes that reduce power consumption, such as half-duplex communications (e.g., a mode that supports one-way communication via transmission or reception, but not transmission and reception simultaneously). In some examples, half-duplex communications may be performed at a reduced peak rate. Other power conservation techniques for the UEs  115  include entering a power saving deep sleep mode when not engaging in active communications, operating over a limited bandwidth (e.g., according to narrowband communications), or a combination of these techniques. For example, some UEs  115  may be configured for operation using a narrowband protocol type that is associated with a defined portion or range (e.g., set of subcarriers or resource blocks (RBs)) within a carrier, within a guard-band of a carrier, or outside of a carrier. 
     The wireless communications system  100  may be configured to support ultra-reliable communications or low-latency communications, or various combinations thereof. For example, the wireless communications system  100  may be configured to support ultra-reliable low-latency communications (URLLC) or mission critical communications. The UEs  115  may be designed to support ultra-reliable, low-latency, or critical functions (e.g., mission critical functions). Ultra-reliable communications may include private communication or group communication and may be supported by one or more mission critical services such as mission critical push-to-talk (MCPTT), mission critical video (MCVideo), or mission critical data (MCData). Support for mission critical functions may include prioritization of services, and mission critical services may be used for public safety or general commercial applications. The terms ultra-reliable, low-latency, mission critical, and ultra-reliable low-latency may be used interchangeably herein. 
     In some examples, a UE  115  may also be able to communicate directly with other UEs  115  over a device-to-device (D2D) communication link  135  (e.g., using a peer-to-peer (P2P) or D2D protocol). One or more UEs  115  utilizing D2D communications may be within the geographic coverage area  110  of a base station  105 . Other UEs  115  in such a group may be outside the geographic coverage area  110  of a base station  105  or be otherwise unable to receive transmissions from a base station  105 . In some examples, groups of the UEs  115  communicating via D2D communications may utilize a one-to-many (1:M) system in which each UE  115  transmits to every other UE  115  in the group. In some examples, a base station  105  facilitates the scheduling of resources for D2D communications. In other cases, D2D communications are carried out between the UEs  115  without the involvement of a base station  105 . 
     In some systems, the D2D communication link  135  may be an example of a communication channel, such as a sidelink communication channel, between vehicles (e.g., UEs  115 ). In some examples, vehicles may communicate using vehicle-to-everything (V2X) communications, vehicle-to-vehicle (V2V) communications, or some combination of these. A vehicle may signal information related to traffic conditions, signal scheduling, weather, safety, emergencies, or any other information relevant to a V2X system. In some examples, vehicles in a V2X system may communicate with roadside infrastructure, such as roadside units, or with the network via one or more network nodes (e.g., base stations  105 ) using vehicle-to-network (V2N) communications, or with both. 
     The core network  130  may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The core network  130  may be an evolved packet core (EPC) or 5G core (5GC), which may include at least one control plane entity that manages access and mobility (e.g., a mobility management entity (MME), an access and mobility management function (AMF)) and at least one user plane entity that routes packets or interconnects to external networks (e.g., a serving gateway (S-GW), a Packet Data Network (PDN) gateway (P-GW), or a user plane function (UPF)). The control plane entity may manage non-access stratum (NAS) functions such as mobility, authentication, and bearer management for the UEs  115  served by the base stations  105  associated with the core network  130 . User IP packets may be transferred through the user plane entity, which may provide IP address allocation as well as other functions. The user plane entity may be connected to the network operators IP services  150 . The operators IP services  150  may include access to the Internet, Intranet(s), an IP Multimedia Subsystem (IMS), or a Packet-Switched Streaming Service. 
     Some of the network devices, such as a base station  105 , may include subcomponents such as an access network entity  140 , which may be an example of an access node controller (ANC). Each access network entity  140  may communicate with the UEs  115  through one or more other access network transmission entities  145 , which may be referred to as radio heads, smart radio heads, or transmission/reception points (TRPs). Each access network transmission entity  145  may include one or more antenna panels. In some configurations, various functions of each access network entity  140  or base station  105  may be distributed across various network devices (e.g., radio heads and ANCs) or consolidated into a single network device (e.g., a base station  105 ). 
     The wireless communications system  100  may operate using one or more frequency bands, typically in the range of 300 megahertz (MHz) to 300 gigahertz (GHz). Generally, the region from 300 MHz to 3 GHz is known as the ultra-high frequency (UHF) region or decimeter band because the wavelengths range from approximately one decimeter to one meter in length. The UHF waves may be blocked or redirected by buildings and environmental features, but the waves may penetrate structures sufficiently for a macro cell to provide service to the UEs  115  located indoors. The transmission of UHF waves may be associated with smaller antennas and shorter ranges (e.g., less than 100 kilometers) compared to transmission using the smaller frequencies and longer waves of the high frequency (HF) or very high frequency (VHF) portion of the spectrum below 300 MHz. 
     The wireless communications system  100  may also operate in a super high frequency (SHF) region using frequency bands from 3 GHz to 30 GHz, also known as the centimeter band, or in an extremely high frequency (EHF) region of the spectrum (e.g., from 30 GHz to 300 GHz), also known as the millimeter band. In some examples, the wireless communications system  100  may support millimeter wave (mmW) communications between the UEs  115  and the base stations  105 , and EHF antennas of the respective devices may be smaller and more closely spaced than UHF antennas. In some examples, this may facilitate use of antenna arrays within a device. The propagation of EHF transmissions, however, may be subject to even greater atmospheric attenuation and shorter range than SHF or UHF transmissions. The techniques disclosed herein may be employed across transmissions that use one or more different frequency regions, and designated use of bands across these frequency regions may differ by country or regulating body. 
     The wireless communications system  100  may utilize both licensed and unlicensed radio frequency spectrum bands. For example, the wireless communications system  100  may employ License Assisted Access (LAA), LTE-Unlicensed (LTE-U) radio access technology, or NR technology in an unlicensed band such as the 5 GHz industrial, scientific, and medical (ISM) band. When operating in unlicensed radio frequency spectrum bands, devices such as the base stations  105  and the UEs  115  may employ carrier sensing for collision detection and avoidance. In some examples, operations in unlicensed bands may be based on a carrier aggregation configuration in conjunction with component carriers operating in a licensed band (e.g., LAA). Operations in unlicensed spectrum may include downlink transmissions, uplink transmissions, P2P transmissions, or D2D transmissions, among other examples. 
     A base station  105  or a UE  115  may be equipped with multiple antennas, which may be used to employ techniques such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communications, or beamforming. The antennas of a base station  105  or a UE  115  may be located within one or more antenna arrays or antenna panels, which may support MIMO operations or transmit or receive beamforming. For example, one or more base station antennas or antenna arrays may be co-located at an antenna assembly, such as an antenna tower. In some examples, antennas or antenna arrays associated with a base station  105  may be located in diverse geographic locations. A base station  105  may have an antenna array with a number of rows and columns of antenna ports that the base station  105  may use to support beamforming of communications with a UE  115 . Likewise, a UE  115  may have one or more antenna arrays that may support various MIMO or beamforming operations. Additionally or alternatively, an antenna panel may support radio frequency beamforming for a signal transmitted via an antenna port. 
     The base stations  105  or the UEs  115  may use MIMO communications to exploit multipath signal propagation and increase the spectral efficiency by transmitting or receiving multiple signals via different spatial layers. Such techniques may be referred to as spatial multiplexing. The multiple signals may, for example, be transmitted by the transmitting device via different antennas or different combinations of antennas. Likewise, the multiple signals may be received by the receiving device via different antennas or different combinations of antennas. Each of the multiple signals may be referred to as a separate spatial stream and may carry bits associated with the same data stream (e.g., the same codeword) or different data streams (e.g., different codewords). Different spatial layers may be associated with different antenna ports used for channel measurement and reporting. MIMO techniques include single-user MIMO (SU-MIMO), where multiple spatial layers are transmitted to the same receiving device, and multiple-user MIMO (MU-MIMO), where multiple spatial layers are transmitted to multiple devices. 
     Beamforming, which may also be referred to as spatial filtering, directional transmission, or directional reception, is a signal processing technique that may be used at a transmitting device or a receiving device (e.g., a base station  105 , a UE  115 ) to shape or steer an antenna beam (e.g., a transmit beam, a receive beam) along a spatial path between the transmitting device and the receiving device. Beamforming may be achieved by combining the signals communicated via antenna elements of an antenna array such that some signals propagating at particular orientations with respect to an antenna array experience constructive interference while others experience destructive interference. The adjustment of signals communicated via the antenna elements may include a transmitting device or a receiving device applying amplitude offsets, phase offsets, or both to signals carried via the antenna elements associated with the device. The adjustments associated with each of the antenna elements may be defined by a beamforming weight set associated with a particular orientation (e.g., with respect to the antenna array of the transmitting device or receiving device, or with respect to some other orientation). 
     A base station  105  or a UE  115  may use beam sweeping techniques as part of beam forming operations. For example, a base station  105  may use multiple antennas or antenna arrays (e.g., antenna panels) to conduct beamforming operations for directional communications with a UE  115 . Some signals (e.g., synchronization signals, reference signals, beam selection signals, or other control signals) may be transmitted by a base station  105  multiple times in different directions. For example, the base station  105  may transmit a signal according to different beamforming weight sets associated with different directions of transmission. Transmissions in different beam directions may be used to identify (e.g., by a transmitting device, such as a base station  105 , or by a receiving device, such as a UE  115 ) a beam direction for later transmission or reception by the base station  105 . 
     Some signals, such as data signals associated with a particular receiving device, may be transmitted by a base station  105  in a single beam direction (e.g., a direction associated with the receiving device, such as a UE  115 ). In some examples, the beam direction associated with transmissions along a single beam direction may be determined based on a signal that was transmitted in one or more beam directions. For example, a UE  115  may receive one or more of the signals transmitted by the base station  105  in different directions and may report to the base station  105  an indication of the signal that the UE  115  received with a highest signal quality or an otherwise acceptable signal quality. 
     In some examples, transmissions by a device (e.g., by a base station  105  or a UE  115 ) may be performed using multiple beam directions, and the device may use a combination of digital precoding or radio frequency beamforming to generate a combined beam for transmission (e.g., from a base station  105  to a UE  115 ). The UE  115  may report feedback that indicates precoding weights for one or more beam directions, and the feedback may correspond to a configured number of beams across a system bandwidth or one or more sub-bands. The base station  105  may transmit a reference signal (e.g., a cell-specific reference signal (CRS), a channel state information reference signal (CSI-RS)), which may be precoded or unprecoded. The UE  115  may provide feedback for beam selection, which may be a precoding matrix indicator (PMI) or codebook-based feedback (e.g., a multi-panel type codebook, a linear combination type codebook, a port selection type codebook). Although these techniques are described with reference to signals transmitted in one or more directions by a base station  105 , a UE  115  may employ similar techniques for transmitting signals multiple times in different directions (e.g., for identifying a beam direction for subsequent transmission or reception by the UE  115 ) or for transmitting a signal in a single direction (e.g., for transmitting data to a receiving device). 
     A receiving device (e.g., a UE  115 ) may try multiple receive configurations (e.g., directional listening) when receiving various signals from the base station  105 , such as synchronization signals, reference signals, beam selection signals, or other control signals. For example, a receiving device may try multiple receive directions by receiving via different antenna subarrays, by processing received signals according to different antenna subarrays, by receiving according to different receive beamforming weight sets (e.g., different directional listening weight sets) applied to signals received at multiple antenna elements of an antenna array, or by processing received signals according to different receive beamforming weight sets applied to signals received at multiple antenna elements of an antenna array, any of which may be referred to as “listening” according to different receive configurations or receive directions. In some examples, a receiving device may use a single receive configuration to receive along a single beam direction (e.g., when receiving a data signal). The single receive configuration may be aligned in a beam direction determined based on listening according to different receive configuration directions (e.g., a beam direction determined to have a highest signal strength, highest signal-to-noise ratio (SNR), or otherwise acceptable signal quality based on listening according to multiple beam directions). 
     The wireless communications system  100  may be a packet-based network that operates according to a layered protocol stack. In the user plane, communications at the bearer or Packet Data Convergence Protocol (PDCP) layer may be IP-based. A Radio Link Control (RLC) layer may perform packet segmentation and reassembly to communicate over logical channels. A Medium Access Control (MAC) layer may perform priority handling and multiplexing of logical channels into transport channels. The MAC layer may also use error detection techniques, error correction techniques, or both to support retransmissions at the MAC layer to improve link efficiency. In the control plane, the Radio Resource Control (RRC) protocol layer may provide establishment, configuration, and maintenance of an RRC connection between a UE  115  and a base station  105  or a core network  130  supporting radio bearers for user plane data. At the physical layer, transport channels may be mapped to physical channels. 
     The UEs  115  and the base stations  105  may support retransmissions of data to increase the likelihood that data is received successfully. Hybrid automatic repeat request (HARQ) feedback is one technique for increasing the likelihood that data is received correctly over a communication link  125 . HARQ may include a combination of error detection (e.g., using a cyclic redundancy check (CRC)), forward error correction (FEC), and retransmission (e.g., automatic repeat request (ARQ)). HARQ may improve throughput at the MAC layer in poor radio conditions (e.g., low signal-to-noise conditions). In some examples, a device may support same-slot HARQ feedback, where the device may provide HARQ feedback in a specific slot for data received in a previous symbol in the slot. In other cases, the device may provide HARQ feedback in a subsequent slot, or according to some other time interval. 
     According to some aspects, a UE  115  may support reporting CSI on a per-partial band basis. The UE  115  may receive a configuration message that indicates one or more partial bands and select one or more antenna ports (e.g., CSI-RS ports) for each partial band of the one or more partial bands. The UE  115  may receive a reference signal (e.g., a CSI-RS) at the selected one or more antenna ports, calculate CSI that includes a linear combination of the selected one or more antenna ports for each partial band, and transmit the CSI to a base station  105 . The CSI may include an indication of the selected antenna ports and linear combination coefficients for each partial band of the one or more partial bands. Reporting CSI on a per-partial band basis may improve the quality of the CSI as well as a data transmission rate between the UE  115  and the base station  105 . 
       FIG.  2    illustrates an example of a wireless communications system  200  that supports channel state information reporting for partial bands in accordance with aspects of the present disclosure. In some examples, wireless communications system  200  may implement aspects of wireless communication system  100 , as described with reference to  FIG.  1   . The wireless communications system  200  includes base station  105 - a  and UE  115 - a . Generally, the wireless communication system  200  illustrates an example where UE  115 - a  transmits a CSI  205  to base station  105 - a , and the CSI  205  may include partial band CSI  210 - a  and/or partial band CSI  210 - b.    
     In some cases, a base station may transmit a precoded CSI-RS to a UE over a system bandwidth based on spatial and delay reciprocity, and the UE may transmit a CSI report to the base station based on receiving the precoded CSI-RS. A mismatch between uplink and downlink bands may be associated with poor spatial and delay reciprocity and impact the channel information included in the CSI report. For example, a BS may determine a spatial domain basis and frequency domain basis used for the precoding of CSI-RS based on UL channel estimation. If there is poor spatial and delay reciprocity between uplink and downlink channel, the determined SD/FD basis using uplink channel is different compared to the dominant SD/FD basis in the downlink channel. If a UE reports CSI based on CSI-RS precoding with SD/FD bases biased from the dominant SD/FD basis of downlink channel, the channel information included in the CSI report would have lower quality. UE  115 - a  may transmit a CSI  205  to base station  105 - a , and the CSI  205  may include one or more partial band CSIs  210 . Transmitting one or more partial band CSIs to base station  105 - a  may support base station  105 - a  in determining different channel conditions for the different partial bands instead of assuming a uniform set of channel conditions for the entire system bandwidth. In some cases, base station  105 - a  may determine different data transmission configurations (e.g., MCSs) for the different portions of the system bandwidth, thereby improving system efficiency and data throughput. 
     UE  115 - a  may transmit a sounding reference signal (SRS) to base station  105 - a , and base station  105 - a  may transmit a CSI-RS to UE  115 - a  based on receiving the SRS received from UE  105 - a . UE  115 - a  may receive the CSI-RS from base station  105 - a , identify one or more partial bands, determine one or more partial band CSIs  210  corresponding to the one or more partial bands, and transmit the one or more partial band CSIs  210  to base station  105 - a . The width of the partial bands may be smaller than the width of the system bandwidth and larger than the width of a subband (e.g., frequency domain unit). In some cases, UE  115 - a  may select a subset of total antenna ports (e.g., CSI-RS ports) for each partial band. UE  115 - a  may select the same subset of total antenna ports for different partial bands for each layer or across all layers, different subsets of total antenna ports for different partial bands for each layer or across all layers, or any combination thereof. As noted above, in some cases the antenna ports may be CSI-RS ports. 
     In some cases, base station  105 - a  may configure UE  115 - a  with a number of CSI-RS ports or a number of CSI-RS ports UE  115 - a  may select. Base station  105 - a  may additionally or alternatively configure UE  115 - a  with a number of partial bands. For example, base station  105 - a  may configure UE  115 - a  by transmitting a message that includes a pair of numbers (e.g., {32 1}, {24, 1}, {16 1}, {16 2}, {12 1}, {12 2}, {12 3}, {8 1}, {8 2}, {8 3}, {8 4}, etc.). One of the numbers in the pair (e.g., the first number) may correspond to a number of CSI-RS ports or a number of CSI-RS ports UE  115 - a  is allowed to select (for each layer or across all layers), and another number in the pair (e.g., the second number) may correspond to the number of partial bands. The configuration may be subject to the capability or preference of UE  115 - a . In some examples, UE  115 - a  may signal to base station  105 - a  a partial band capability and/or a port capability, and base station  105 - a  may configure UE  115 - a  based on the signaled capability. For example, UE  115 - a  may signal a partial band capability of 1 to base station  105 - a , and base station  105 - a  may configure the UE based on the signaled capability (e.g., base station  105 - a  may configure UE  115 - a  with one of {32 1}, {24, 1}, {16 1}, or {12 1}). In an additional or alternative example, UE  115 - a  may signal a port capability of 8 to base station  105 - a , and base station  105 - a  may configure the UE based on the signaled capability (e.g., base station  105 - a  may configure UE  115 - a  with one of {8 1}, {8 2}, {8 3}, or {8 4}). In an additional or alternative example, UE  115 - a  may signal a max partial band capability of 2 to base station  105 - a , and base station  105 - a  may configure the UE based on the signaled capability (e.g., base station  105 - a  may configure UE  115 - a  with one of {32 1}, {24, 1}, {16 1}, {12 1}, {16 2}, {12 2}, {8 2}). 
     In some cases, base station  105 - a  may configure UE  115 - a  with a number of ports or a number of ports the UE is allowed to select for each layer or across all layers, as well as a partial band size. For example, base station  105 - a  may configure UE  115 - a  by transmitting a message that includes a pair of numbers (e.g., {32 ⅛}, {24, ⅛}, {16 ⅛}, {16 ¼}, {12 ⅛}, {12 ¼}, {12 ½}, {8 ⅛}, {8 ¼}, {8 ½}, {8 1}, etc.). One of the numbers (e.g., the first number) may correspond to the number of ports or the number of ports the UE is allowed to select for each layer or across all layers, and the second number may correspond to the number of partial bands per subband (e.g., less than or equal to 1 partial bands per subband) or the ratio between the size of the subband and the size of the partial band. Base station  105 - a  may configure  115 - a  based on a capability of UE  115 - a . In some examples, UE  115 - a  may signal to base station  105 - a  a subband capability, and base station  105 - a  may configure UE  115 - a  based on the signaled capability. For example, UE  115 - a  may signal a capability of 8 subbands per partial band to base station  105 - a , and base station  105 - a  may configure UE  115 - a  based on the signaled capability (e.g., base station  105 - a  may configure UE  115 - a  with one or {32 ⅛}, {24, ⅛}, {16 ⅛}, {12 ⅛}, {8 ⅛}). In an additional or alternative example, UE  115 - a  may signal a max partial band capability of minimum 4 subbands per partial band to base station  105 - a , and base station  105 - a  may configure the UE based on the signaled capability (e.g., base station  105 - a  may configure UE  115 - a  with one of {32 ⅛}, {24, ⅛}, {16 ⅛}, {12 ⅛}, {8 ⅛}, {16 ¼}, {12 ¼}, {8 ¼}). 
     The partial band size (e.g., the number of subbands in a partial band) may be based on a number of subbands and a number of partial bands. In some examples, UE  115 - a  may be configured with a number of subbands (e.g., 13 subbands) and base station  105 - a  may further configure UE  115 - a  with a number of partial bands (e.g., 2 partial bands). For example, the first partial band may have a size of 6 subbands and the second partial band may have a size of 7 subbands. In some cases, UE  115 - a  may be configured with a large number of ports and a small number of partial bands. In some additional or alternative cases, UE  115 - a  may be configured with a small number of ports and either a large or small number of partial bands. Configuring UE  115 - a  with a large number of partial bands may support increase the granularity and/or quality of CSI  205 , and configuring UE  115 - a  with a small number of partial bands may decrease the payload size of CSI  205 , thereby reducing system resource usage. 
       FIG.  3    illustrates an example of a channel state information reporting technique  300  that supports channel state information reporting for partial bands in accordance with aspects of the present disclosure. In some examples, channel state information reporting technique  300  may implement aspects of wireless communication system  100 , as described with reference to  FIG.  1   . A partial band  305  may include a number of ports and a number of FD units  320  (e.g., subbands, resource blocks, etc.). A UE may report CSI for one or more partial bands  305 , which may improve CSI quality and improve system efficiency. The channel state information reporting techniques  300  may illustrate a number of CSI-RS precoders that each correspond to an FD unit  320  of a partial band  305 . In some cases, the expression b i  is an nTx*1 vector representing an SD basis where nTx is the number of antenna ports at the gNB, the expression f m   H  is a 1*N 3 /2 FD basis where f m   H (n) denotes the n th  entry of f m   H , and N 3  is the number of FD units across all partial bands. For each port  310 , the combination of FD basis and SD basis may be different. Each partial band  305  may use the same FD/SD pair, a different FD/SD pair, or any combination thereof. 
     A UE may report partial band CSI to a base station, and the partial band CSI may indicate a PMI that is a linear combination of ports. In some cases, the PMI for certain layer l on a partial band  305  may be expressed by W j , where “j” is the index of the partial band  305 . For example, the PMI on partial band  305 - a  may be expressed by W j =Σv i     k     ,j,l *C i     k     ,j,l , where v i     k     ,j,l  is the size of P×1 with only one “1” in row i k  indicating port i k  is selected for layer l and partial band j, P is the total number of CSI-RS ports, and C i     k     ,j,l  is a linear combination coefficient. In some cases, the UE may report CSI for a group of partial bands, and the CSI may indicate a PMI for each partial band  305  in the group of partial bands. 
     In some cases, a number of ports may be selected for each partial band  305 . In some examples, a UE may select a set of ports for one more partial bands  305 , and the selected set of ports may be signaled to a base station (e.g., via a CSI-RS resource indication (CRI). For example, port  310 - a  may correspond to port  0  for partial band  305 - a , port  310 - b  may correspond to port  1  for partial band  305 - a , port  310 - c  may correspond to port  2  for partial band  305 - a , and port  310 - d  may correspond to port  3  for partial band  305 - a , port  315 - a  may correspond to port  0  for partial band  305 - b , port  315 - b  may correspond to port  1  for partial band  305 - b , port  315 - c  may correspond to port  2  for partial band  305 - b , and port  315 - d  may correspond to port  3  for partial band  305 - b . In some cases, the UE may indicate a selected set of ports to a base station, and the selected set of ports may be common for all partial bands  305 . 
     In some cases, CSI-RS on different partial bands are transmitted in the same CSI-RS resource (i.e., ports  310  and  315  are in the same CSI-RS resource), a UE may select ports for each partial band from the same CSI-RS resource (UE may report CRI to indicate the resource if there are multiple resources). In some cases, CSI-RS on different partial bands are transmitted in different CSI-RS resources, a UE may select ports for each partial band from the corresponding CSI-RS resource. Ports  310  are in resource 1 and ports  315  are in resource 2, then UE selects ports for partial band  305 - a  using resource 1 and selects ports for partial band  305 - b  using resource 2. In some cases, there are N_PB partial bands, and M*N_PB resources. In each resource, the CSI-RS is transmitted on a certain partial band, so there are M resources transmitted on certain partial bands, i.e., resource 1 to resource M comprise CSI-RS on partial band 1, resource M+1 to resource 2*M comprise CSI-RS on partial band 2, . . . resource n*M+1 to resource (n+1)*M comprise CSI-RS on partial band n+1, . . . , resource (N_PB−1)*M+1 to resource N_PB*M comprise CSI-RS on partial band N_PB. UE would report CRI to indicate one resource from resource 1 to resource M for partial band 1, one resource from resource M+1 to resource 2*M for on partial band 2, . . . , one resource from resource n*M+1 to resource (n+1)*M for partial band n+1, . . . , one resource from resource (N_PB−1)*M+1 to resource N_PB*M for partial band N_PB, and UE may further report port selection from the corresponding selected resource for the associated partial band. 
     A UE may select ports that are specific to each partial band  305 . In some cases, the UE may perform a one-step port selection wherein a number of partial band specific port sets are selected and reported to a base station. In some examples, the UE may be configured with a resource (e.g., a total set of ports that is common to all partial bands  305 ), and the UE may select first set of ports (e.g., ports  310 ) applied to each layer or across layers from the resource for partial band  305 - a  and a second set of ports (e.g., ports  315 ) from the same resource for partial band  305 - b . In some additional or alternative examples, the UE may be configured with partial band specific resources, and the UE may select a set of ports applied to each layer or across layers from a partial band specific resource for each partial band  305 . For example, a UE may select ports  310  from a set of ports in the resource associated with partial band  305 - a  for partial band  305 - a , and the UE may select ports  315  from a set of ports in the resource associated with partial band  305 - b  for partial band  305 - b.    
     A UE may perform a two-step port selection. In two-selection, a UE may report an intermediate set of ports that is common to (each layer or across layers) all partial bands  305  as well as a number of partial band specific port sets (applied to each layer or across layers) that are selected from the intermediate set. In some examples, a UE may independently report a first set of ports (e.g., ports  310 ) from the intermediate set of ports and a second set of ports (e.g., ports  315 ) from the intermediate set of ports. The size of the intermediate set may be configurable. In some cases, a UE may be pre-configured with an intermediate set size, or a base station may indicate to the UE an intermediate set size. In some cases, the size of the intermediate set may be derived based on the number of ports allowed to be selected on each partial band for each layer or across all layers. In some cases, a UE may report the size of the intermediate set (e.g., report the size to a base station). In some additional or alternative examples, a UE may report a set of ports that is common to all partial bands  305  as well as a set of ports that is associated with a particular partial band  305 . The UE may additionally report a partial band specific set of ports for each partial band  305 , and each partial band specific set of ports may be independently chosen from the union of the set of ports that is common to all partial bands  305  and the set of ports that is associated with a particular partial band  305 . 
     In some cases, a UE may be configured (e.g., via an RRC procedure) with a frequency domain restriction for channel measurement, and the UE may calculate channel state information based on the frequency domain restriction. For example, the UE may be configured to perform a channel measurement in partial band  305 - a  as well as partial band  305 - b , and the UE may calculate channel state information for partial band  305 - a  and partial band  305 - b . For partial band CSI reporting, if a frequency domain restriction for channel measurement is configured, the UE shall derive the channel measurements for computing CSI value reported in uplink slot “n” based on only the NZP CSI-RS, within each partial band associated with the CSI resource setting. 
     In some additional or alternative cases, a UE may be configured (e.g., via an RRC procedure) with an interference measurement restriction, and the UE may measure interference and calculate channel state information based on the interference measurement restriction. For example, the UE may be configured to perform an interference measurement in partial band  305 - a  as well as partial band  305 - b , and the UE may measure interference and calculate channel state information for partial band  305 - a  and partial band  305 - b . For partial band CSI reporting, if an interference measurement restriction is configured, the UE shall derive the interference measurements for computing CSI value reported in uplink slot “n” based on only the NZP CSI-RS, within each partial band associated with the CSI resource setting. 
       FIG.  4    illustrates an example of a process flow  400  that supports channel state information reporting for partial bands in accordance with aspects of the present disclosure. In some examples, process flow  400  may implement aspects of wireless communication system  100 . UE  115 - b  and/or base station  105 - b  may support partial band CSI (e.g., CSI that is associated with a partial band) in accordance with aspects of the present disclosure. Partial band CSI may be more granular than system wide CSI and may improve the quality of the channel state information reported to a base station. Alternative examples of the following may be implemented, where some steps are performed in a different order than described or are not performed at all. In some cases, steps may include additional features not mentioned below, or further steps may be added. 
     At  405 , UE  115 - b  may receive a configuration message from base station  105 - b , and the configuration message may include an indication of one or more partial bands for CSI reporting. Each partial band of the one or more partial bands may be less than a system bandwidth and include a plurality of frequency domain units associated with a precoder. 
     At  410 , UE  115 - b  may select one or more antenna ports (e.g., CSI-RS ports) for each partial band of the one or more partial bands based on the configuration message. For example, the configuration message may indicate a group of antenna ports, a number of antenna ports, a minimum number of antenna ports, or a maximum number of antenna ports, and UE  115 - b  may select the one or more antenna ports based on the configuration message. 
     At  415 , UE  115 - b  may receive a reference signal (e.g., a CSI-RS) from base station  105 - a . UE  115 - b  may measure the received reference signal at the selected one or more antenna ports and generate CSI coefficients for the one or more partial bands. 
     At  420 , UE  115 - b  may calculate CSI including a linear combination of the selected one or more antenna ports for each partial band. In some examples, the CSI may include or be based on the generated CSI coefficients. In some cases, UE  115 - b  may select one or more antenna ports (e.g., CSI-RS ports) for each partial band at  420 . For example, UE  115 - b  may refrain from selecting antenna ports at  410 , and UE  115 - b  may select one or more antenna ports at  420 . The CSI may include an indication of a PMI that includes the port selection and the linear combination coefficients. In some cases, the CSI may include a CQI, and the CQI may be calculated based on the PMI. 
     At  425 , UE  115 - b  may transmit the CSI to base station  105 - b . The CSI may include an indication of the selected antenna ports and linear combination coefficients for each partial band of the one or more partial bands. 
     Base station  105 - b  may transmit updated transmission parameters to UE  115 - b  for further communication with base station  105 - b . The updated transmission parameters may increase the data rate of UE  115 - b  and be based on receiving the CSI coefficients. 
     In some cases, UE  115 - b  may receive an aperiodic CSI triggering and report CSI to a base station based on receiving the aperiodic CSI trigger. UE  115 - b  may calculate and transmit CSI to base station  105 - b  based on receiving an aperiodic CSI trigger, and the CSI may include a linear combination of one or more antenna ports for each partial band of a group of one or more partial bands. 
       FIG.  5    shows a block diagram  500  of a device  505  that supports channel state information reporting for partial bands in accordance with aspects of the present disclosure. The device  505  may be an example of aspects of a UE  115  as described herein. The device  505  may include a receiver  510 , a channel state information manager  515 , and a transmitter  520 . The device  505  may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses). 
     The receiver  510  may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to channel state information reporting for partial bands, etc.). Information may be passed on to other components of the device  505 . The receiver  510  may be an example of aspects of the transceiver  820  described with reference to  FIG.  8   . The receiver  510  may utilize a single antenna or a set of antennas. 
     The channel state information manager  515  may receive from a base station a configuration message including an indication of one or more partial bands for channel state information reporting, where each partial band of the one or more partial bands is less than a system bandwidth and includes a set of frequency domain units associated with a precoder, select one or more antenna ports for each partial band of the one or more partial bands based on the configuration message, calculate channel state information including a linear combination of the selected one or more antenna ports for each partial band, based on receiving the configuration message, and transmit the channel state information including at least an indication of the selected antenna ports and linear combination coefficients for each partial band of the one or more partial bands. The channel state information manager  515  may be an example of aspects of the channel state information manager  810  described herein. 
     The channel state information manager  515 , or its sub-components, may be implemented in hardware, code (e.g., software or firmware) executed by a processor, or any combination thereof. If implemented in code executed by a processor, the functions of the channel state information manager  515 , or its sub-components may be executed by a general-purpose processor, a DSP, an application-specific integrated circuit (ASIC), a FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described in the present disclosure. 
     The channel state information manager  515 , or its sub-components, may be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations by one or more physical components. In some examples, the channel state information manager  515 , or its sub-components, may be a separate and distinct component in accordance with various aspects of the present disclosure. In some examples, the channel state information manager  515 , or its sub-components, may be combined with one or more other hardware components, including but not limited to an input/output (I/O) component, a transceiver, a network server, another computing device, one or more other components described in the present disclosure, or a combination thereof in accordance with various aspects of the present disclosure. 
     The transmitter  520  may transmit signals generated by other components of the device  505 . In some examples, the transmitter  520  may be collocated with a receiver  510  in a transceiver module. For example, the transmitter  520  may be an example of aspects of the transceiver  820  described with reference to  FIG.  8   . The transmitter  520  may utilize a single antenna or a set of antennas. The channel state information manager  515  may improve the quality of CSI reported by the device  505 , increase the data rate of the device  505 , and improve the link quality between the device  505  and a base station. 
       FIG.  6    shows a block diagram  600  of a device  605  that supports channel state information reporting for partial bands in accordance with aspects of the present disclosure. The device  605  may be an example of aspects of a device  505 , or a UE  115  as described herein. The device  605  may include a receiver  610 , a channel state information manager  615 , and a transmitter  635 . The device  605  may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses). 
     The receiver  610  may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to channel state information reporting for partial bands, etc.). Information may be passed on to other components of the device  605 . The receiver  610  may be an example of aspects of the transceiver  820  described with reference to  FIG.  8   . The receiver  610  may utilize a single antenna or a set of antennas. 
     The channel state information manager  615  may be an example of aspects of the channel state information manager  515  as described herein. The channel state information manager  615  may include a configuration message processor  620 , an antenna port selector  625 , and a channel state information generator  630 . The channel state information manager  615  may be an example of aspects of the channel state information manager  810  described herein. 
     The configuration message processor  620  may receive from a base station a configuration message including an indication of one or more partial bands for channel state information reporting, where each partial band of the one or more partial bands is less than a system bandwidth and includes a set of frequency domain units associated with a precoder. 
     The antenna port selector  625  may select one or more antenna ports for each partial band of the one or more partial bands based on the configuration message. 
     The channel state information generator  630  may calculate channel state information including a linear combination of the selected one or more antenna ports for each partial band, based on receiving the configuration message and transmit the channel state information including at least an indication of the selected antenna ports and linear combination coefficients for each partial band of the one or more partial bands. 
     The transmitter  635  may transmit signals generated by other components of the device  605 . In some examples, the transmitter  635  may be collocated with a receiver  610  in a transceiver module. For example, the transmitter  635  may be an example of aspects of the transceiver  820  described with reference to  FIG.  8   . The transmitter  635  may utilize a single antenna or a set of antennas. 
       FIG.  7    shows a block diagram  700  of a channel state information manager  705  that supports channel state information reporting for partial bands in accordance with aspects of the present disclosure. The channel state information manager  705  may be an example of aspects of a channel state information manager  515 , a channel state information manager  615 , or a channel state information manager  810  described herein. The channel state information manager  705  may include a configuration message processor  710 , an antenna port selector  715 , a channel state information generator  720 , a capability message generator  725 , and a channel resource indication generator  730 . Each of these modules may communicate, directly or indirectly, with one another (e.g., via one or more buses). 
     The configuration message processor  710  may receive from a base station a configuration message including an indication of one or more partial bands for channel state information reporting, where each partial band of the one or more partial bands is less than a system bandwidth and includes a set of frequency domain units associated with a precoder. 
     The antenna port selector  715  may select one or more antenna ports for each partial band of the one or more partial bands based on the configuration message. 
     In some examples, selecting the one or more antenna ports includes selecting a subset of a total number of antenna ports for each partial band of the one or more partial bands. 
     In some examples, the antenna port selector  715  may select the one or more antenna ports for each partial band based on the joint indication. 
     In some examples, transmitting to the base station a report of the one or more antenna ports selected for each partial band of the one or more partial bands, where the report of the one or more antenna ports selected for each partial band includes an indication of a first set of antenna ports common to all partial bands of the one or more partial bands and, for each partial band of the one or more partial bands, an indication of a second set of antenna ports independently selected for that partial band, where the second set of antenna ports for each partial band is from the first set of antenna ports. 
     In some examples, the antenna port selector  715  may receive from the base station a configuration of a size of the first set of antenna ports and a size of the second set of antenna ports. 
     In some cases, a same subset of one or more CSI-RS ports is selected for each partial band of the one or more partial bands. 
     In some cases, the antenna ports include channel state information reference signal (CSI-RS) ports and the configuration message further includes a joint indication of partial bands and a numerical quantity of the CSI-RS ports. 
     In some cases, a number of partial bands, a partial band size, or a ratio of partial bands to frequency unit size; and one or more of: a number of total CSI-RS ports or a number of CSI-RS ports to be selected for each partial band. 
     The channel state information generator  720  may calculate channel state information including a linear combination of the selected one or more antenna ports for each partial band, based on receiving the configuration message. 
     In some examples, the channel state information generator  720  may transmit the channel state information including at least an indication of the selected antenna ports and linear combination coefficients for each partial band of the one or more partial bands. 
     In some examples, calculating the channel state information includes separately precoding each partial band of the one or more partial bands. 
     In some examples, the channel state information generator  720  may receive, from the base station, a configuration of frequency domain restriction for channel measurement. 
     In some examples, determining that a frequency domain restriction for channel measurement is in place based on the configuration of frequency domain restriction for channel measurement, where calculating the channel information for each partial band of the one or more partial bands includes restricting the channel state measurement to non-zero power channel state information reference signals within each partial band. 
     In some examples, the channel state information generator  720  may receive, from the base station, a configuration of frequency domain restriction for interference measurement. 
     In some examples, determining that a frequency domain restriction for interference measurement is in place based on the configuration of frequency domain restriction for channel measurement, where performing interference measurement for each partial band of the one or more partial bands includes restricting the interference measurement to zero or non-zero interference measurement resources within each partial band. 
     In some cases, the indication of one or more partial bands for channel state reporting includes one or more of a numerical quantity of partial bands for which the UE is to perform channel state measurement, or a partial band size for which the UE is to perform channel state measurement, or a ratio of partial band size to frequency domain unit size. 
     In some cases, the indication of one or more partial bands is dependent on an indication of a numerical quantity of antenna ports to select for each partial band of the one or more partial bands, or a numerical quantity of total antenna ports, and selecting the one or more antenna ports for each partial band is based on the indicated numerical quantity. 
     In some cases, a frequency domain unit of the set of frequency domain units corresponds to a subband size for channel quality indicator (CQI) reporting. 
     The capability message generator  725  may transmit to the base station a capability message indicating a numerical quality of partial bands for which the UE is capable of performing channel measurement, where the configuration message is based on the capability message. 
     The channel resource indication generator  730  may transmit to the base station a report of a resource selection for the channel state measurement for each partial band of the one or more partial bands. 
       FIG.  8    shows a diagram of a system  800  including a device  805  that supports channel state information reporting for partial bands in accordance with aspects of the present disclosure. The device  805  may be an example of or include the components of device  505 , device  605 , or a UE  115  as described herein. The device  805  may include components for bi-directional voice and data communications including components for transmitting and receiving communications, including a channel state information manager  810 , an I/O controller  815 , a transceiver  820 , an antenna  825 , memory  830 , and a processor  840 . These components may be in electronic communication via one or more buses (e.g., bus  845 ). 
     The channel state information manager  810  may receive from a base station a configuration message including an indication of one or more partial bands for channel state information reporting, where each partial band of the one or more partial bands is less than a system bandwidth and includes a set of frequency domain units associated with a precoder, select one or more antenna ports for each partial band of the one or more partial bands based on the configuration message, calculate channel state information including a linear combination of the selected one or more antenna ports for each partial band, based on receiving the configuration message, and transmit the channel state information including at least an indication of the selected antenna ports and linear combination coefficients for each partial band of the one or more partial bands. 
     The I/O controller  815  may manage input and output signals for the device  805 . The I/O controller  815  may also manage peripherals not integrated into the device  805 . In some cases, the I/O controller  815  may represent a physical connection or port to an external peripheral. In some cases, the I/O controller  815  may utilize an operating system such as iOS®, ANDROID®, MS-DOS®, MS-WINDOWS®, OS/2®, UNIX®, LINUX®, or another known operating system. In other cases, the I/O controller  815  may represent or interact with a modem, a keyboard, a mouse, a touchscreen, or a similar device. In some cases, the I/O controller  815  may be implemented as part of a processor. In some cases, a user may interact with the device  805  via the I/O controller  815  or via hardware components controlled by the I/O controller  815 . 
     The transceiver  820  may communicate bi-directionally, via one or more antennas, wired, or wireless links as described above. For example, the transceiver  820  may represent a wireless transceiver and may communicate bi-directionally with another wireless transceiver. The transceiver  820  may also include a modem to modulate the packets and provide the modulated packets to the antennas for transmission, and to demodulate packets received from the antennas. 
     In some cases, the wireless device may include a single antenna  825 . However, in some cases the device may have more than one antenna  825 , which may be capable of concurrently transmitting or receiving multiple wireless transmissions. 
     The memory  830  may include RAM and ROM. The memory  830  may store computer-readable, computer-executable code  835  including instructions that, when executed, cause the processor to perform various functions described herein. In some cases, the memory  830  may contain, among other things, a BIOS which may control basic hardware or software operation such as the interaction with peripheral components or devices. 
     The processor  840  may include a programmable hardware device, (e.g., a general-purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof). In some cases, the processor  840  may be configured to operate a memory array using a memory controller. In other cases, a memory controller may be integrated into the processor  840 . The processor  840  may be configured to execute computer-readable instructions stored in a memory (e.g., the memory  830 ) to cause the device  805  to perform various functions (e.g., functions or tasks supporting channel state information reporting for partial bands). 
     The code  835  may include instructions to implement aspects of the present disclosure, including instructions to support wireless communications. The code  835  may be stored in a non-transitory computer-readable medium such as system memory or other type of memory. In some cases, the code  835  may not be directly executable by the processor  840  but may cause a computer (e.g., when compiled and executed) to perform functions described herein. The channel state information manager  810  may increase the granularity of CSI reported by the device  805 . Increased CSI granularity may enhance the quality of the CSI and improve the efficiency of the device  805 . 
       FIG.  9    shows a block diagram  900  of a device  905  that supports channel state information reporting for partial bands in accordance with aspects of the present disclosure. The device  905  may be an example of aspects of a base station  105  as described herein. The device  905  may include a receiver  910 , a channel state information manager  915 , and a transmitter  920 . The device  905  may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses). 
     The receiver  910  may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to channel state information reporting for partial bands, etc.). Information may be passed on to other components of the device  905 . The receiver  910  may be an example of aspects of the transceiver  1220  described with reference to  FIG.  12   . The receiver  910  may utilize a single antenna or a set of antennas. 
     The channel state information manager  915  may transmit to a UE a configuration message including an indication of one or more partial bands for channel state information reporting, where each partial band of the one or more partial bands is less than a system bandwidth and includes a set of frequency domain units associated with a precoder, receive channel state information including an indication of antenna ports and linear combination coefficients for each partial band of the one or more partial bands based on transmitting the configuration message and the channel state measurement, and communicate with the UE based on receiving the channel state information for each partial band of the one or more partial bands. The channel state information manager  915  may be an example of aspects of the channel state information manager  1210  described herein. 
     The channel state information manager  915 , or its sub-components, may be implemented in hardware, code (e.g., software or firmware) executed by a processor, or any combination thereof. If implemented in code executed by a processor, the functions of the channel state information manager  915 , or its sub-components may be executed by a general-purpose processor, a DSP, an application-specific integrated circuit (ASIC), a FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described in the present disclosure. 
     The channel state information manager  915 , or its sub-components, may be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations by one or more physical components. In some examples, the channel state information manager  915 , or its sub-components, may be a separate and distinct component in accordance with various aspects of the present disclosure. In some examples, the channel state information manager  915 , or its sub-components, may be combined with one or more other hardware components, including but not limited to an input/output (I/O) component, a transceiver, a network server, another computing device, one or more other components described in the present disclosure, or a combination thereof in accordance with various aspects of the present disclosure. 
     The transmitter  920  may transmit signals generated by other components of the device  905 . In some examples, the transmitter  920  may be collocated with a receiver  910  in a transceiver module. For example, the transmitter  920  may be an example of aspects of the transceiver  1220  described with reference to  FIG.  12   . The transmitter  920  may utilize a single antenna or a set of antennas. The channel state information manager  915  may improve the quality of CSI reported by the device  905 , increase the data rate of the device  905 , and improve the link quality between the device  905  and a base station. 
       FIG.  10    shows a block diagram  1000  of a device  1005  that supports channel state information reporting for partial bands in accordance with aspects of the present disclosure. The device  1005  may be an example of aspects of a device  905 , or a base station  105  as described herein. The device  1005  may include a receiver  1010 , a channel state information manager  1015 , and a transmitter  1035 . The device  1005  may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses). 
     The receiver  1010  may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to channel state information reporting for partial bands, etc.). Information may be passed on to other components of the device  1005 . The receiver  1010  may be an example of aspects of the transceiver  1220  described with reference to  FIG.  12   . The receiver  1010  may utilize a single antenna or a set of antennas. 
     The channel state information manager  1015  may be an example of aspects of the channel state information manager  915  as described herein. The channel state information manager  1015  may include a configuration message manager  1020 , an antenna port manager  1025 , and a communications manager  1030 . The channel state information manager  1015  may be an example of aspects of the channel state information manager  1210  described herein. 
     The configuration message manager  1020  may transmit to a UE a configuration message including an indication of one or more partial bands for channel state information reporting, where each partial band of the one or more partial bands is less than a system bandwidth and includes a set of frequency domain units associated with a precoder. 
     The antenna port manager  1025  may receive channel state information including an indication of antenna ports and linear combination coefficients for each partial band of the one or more partial bands based on transmitting the configuration message and the channel state measurement. 
     The communications manager  1030  may communicate with the UE based on receiving the channel state information for each partial band of the one or more partial bands. 
     The transmitter  1035  may transmit signals generated by other components of the device  1005 . In some examples, the transmitter  1035  may be collocated with a receiver  1010  in a transceiver module. For example, the transmitter  1035  may be an example of aspects of the transceiver  1220  described with reference to  FIG.  12   . The transmitter  1035  may utilize a single antenna or a set of antennas. 
       FIG.  11    shows a block diagram  1100  of a channel state information manager  1105  that supports channel state information reporting for partial bands in accordance with aspects of the present disclosure. The channel state information manager  1105  may be an example of aspects of a channel state information manager  915 , a channel state information manager  1015 , or a channel state information manager  1210  described herein. The channel state information manager  1105  may include a configuration message manager  1110 , an antenna port manager  1115 , a communications manager  1120 , a capability message manager  1125 , and a resource selection manager  1130 . Each of these modules may communicate, directly or indirectly, with one another (e.g., via one or more buses). 
     The configuration message manager  1110  may transmit to a UE a configuration message including an indication of one or more partial bands for channel state information reporting, where each partial band of the one or more partial bands is less than a system bandwidth and includes a set of frequency domain units associated with a precoder. 
     In some examples, the configuration message manager  1110  may transmit, to the UE, a configuration of frequency domain restriction for channel measurement. 
     In some examples, the configuration message manager  1110  may receive the channel state information based on channel measurement of non-zero power channel state information reference signals within each partial band. 
     In some examples, the configuration message manager  1110  may transmit, to the UE, a configuration of frequency domain restriction for interference measurement. 
     In some examples, the configuration message manager  1110  may receive the channel state information based on interference measurement of interference measurement resources within each partial band. 
     In some cases, the indication of one or more partial bands for channel state reporting includes one or more of a numerical quantity of partial bands for which the UE is to perform channel state measurement, or a partial band size for which the UE is to perform channel state measurement, or a ratio of partial band size to frequency domain unit size. 
     In some cases, the indication of one or more partial bands is dependent on an indication of a numerical quantity of antenna ports to select for each partial band of the one or more partial bands, or a numerical quantity of total antenna ports, and selecting the one or more antenna ports for each partial band is based on the indicated numerical quantity. 
     The antenna port manager  1115  may receive channel state information including an indication of antenna ports and linear combination coefficients for each partial band of the one or more partial bands based on transmitting the configuration message and the channel state measurement. 
     In some examples, receiving a report from the UE of one or more antenna ports selected for each partial band of the one or more partial bands, where the report of the one or more antenna ports selected for each partial band includes an indication of a first set of antenna ports common to all partial bands of the one or more partial bands and, for each partial band of the one or more partial bands, an indication of a second set of antenna ports independently selected for that partial band, where the second set of antenna ports for each partial band is from the first set of antenna ports. 
     In some examples, the antenna port manager  1115  may transmit to the UE a configuration of a size of the first set of antenna ports and a size of the second set of antenna ports. 
     In some cases, the antenna ports include channel state information reference signal (CSI-RS) ports and the configuration message further includes a joint indication of partial bands and a numerical quantity of the CSI-RS ports. 
     In some cases, the one or more antenna ports for each partial band are selected based on the join indication. 
     In some cases, a number of partial bands, a partial band size, or a ratio of partial bands to frequency unit size; and one or more of: a number of total CSI-RS ports or a number of CSI-RS ports to be selected for each partial band. 
     The communications manager  1120  may communicate with the UE based on receiving the channel state information for each partial band of the one or more partial bands. 
     The capability message manager  1125  may receive a capability message from the UE indicating a numerical quality of partial bands for which the UE is capable of performing channel measurement, where the configuration message is based on the capability message. 
     The resource selection manager  1130  may receive from the UE a report of a resource selection for the channel state measurement for each partial band of the one or more partial bands. 
       FIG.  12    shows a diagram of a system  1200  including a device  1205  that supports channel state information reporting for partial bands in accordance with aspects of the present disclosure. The device  1205  may be an example of or include the components of device  905 , device  1005 , or a base station  105  as described herein. The device  1205  may include components for bi-directional voice and data communications including components for transmitting and receiving communications, including a channel state information manager  1210 , a network communications manager  1215 , a transceiver  1220 , an antenna  1225 , memory  1230 , a processor  1240 , and an inter-station communications manager  1245 . These components may be in electronic communication via one or more buses (e.g., bus  1250 ). 
     The channel state information manager  1210  may transmit to a UE a configuration message including an indication of one or more partial bands for channel state information reporting, where each partial band of the one or more partial bands is less than a system bandwidth and includes a set of frequency domain units associated with a precoder, receive channel state information including an indication of antenna ports and linear combination coefficients for each partial band of the one or more partial bands based on transmitting the configuration message and the channel state measurement, and communicate with the UE based on receiving the channel state information for each partial band of the one or more partial bands. 
     The network communications manager  1215  may manage communications with the core network (e.g., via one or more wired backhaul links). For example, the network communications manager  1215  may manage the transfer of data communications for client devices, such as one or more UEs  115 . 
     The transceiver  1220  may communicate bi-directionally, via one or more antennas, wired, or wireless links as described above. For example, the transceiver  1220  may represent a wireless transceiver and may communicate bi-directionally with another wireless transceiver. The transceiver  1220  may also include a modem to modulate the packets and provide the modulated packets to the antennas for transmission, and to demodulate packets received from the antennas. 
     In some cases, the wireless device may include a single antenna  1225 . However, in some cases the device may have more than one antenna  1225 , which may be capable of concurrently transmitting or receiving multiple wireless transmissions. 
     The memory  1230  may include RAM, ROM, or a combination thereof. The memory  1230  may store computer-readable code  1235  including instructions that, when executed by a processor (e.g., the processor  1240 ) cause the device to perform various functions described herein. In some cases, the memory  1230  may contain, among other things, a BIOS which may control basic hardware or software operation such as the interaction with peripheral components or devices. 
     The processor  1240  may include an intelligent hardware device, (e.g., a general-purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof). In some cases, the processor  1240  may be configured to operate a memory array using a memory controller. In some cases, a memory controller may be integrated into processor  1240 . The processor  1240  may be configured to execute computer-readable instructions stored in a memory (e.g., the memory  1230 ) to cause the device  1205  to perform various functions (e.g., functions or tasks supporting channel state information reporting for partial bands). 
     The inter-station communications manager  1245  may manage communications with other base station  105 , and may include a controller or scheduler for controlling communications with UEs  115  in cooperation with other base stations  105 . For example, the inter-station communications manager  1245  may coordinate scheduling for transmissions to UEs  115  for various interference mitigation techniques such as beamforming or joint transmission. In some examples, the inter-station communications manager  1245  may provide an X2 interface within an LTE/LTE-A wireless communication network technology to provide communication between base stations  105 . 
     The code  1235  may include instructions to implement aspects of the present disclosure, including instructions to support wireless communications. The code  1235  may be stored in a non-transitory computer-readable medium such as system memory or other type of memory. In some cases, the code  1235  may not be directly executable by the processor  1240  but may cause a computer (e.g., when compiled and executed) to perform functions described herein. The channel state information manager  1210  may increase the granularity of CSI reported by the device  1205 . Increased CSI granularity may enhance the quality of the CSI and improve the efficiency of the device  1205 . 
       FIG.  13    shows a flowchart illustrating a method  1300  that supports channel state information reporting for partial bands in accordance with aspects of the present disclosure. The operations of method  1300  may be implemented by a UE  115  or its components as described herein. For example, the operations of method  1300  may be performed by a channel state information manager as described with reference to  FIGS.  5  through  8   . In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the functions described below. Additionally or alternatively, a UE may perform aspects of the functions described below using special-purpose hardware. 
     At  1305 , the UE may receive from a base station a configuration message including an indication of one or more partial bands for channel state information reporting, where each partial band of the one or more partial bands is less than a system bandwidth and includes a set of frequency domain units associated with a precoder. The operations of  1305  may be performed according to the methods described herein. In some examples, aspects of the operations of  1305  may be performed by a configuration message processor as described with reference to  FIGS.  5  through  8   . 
     At  1310 , the UE may select one or more antenna ports for each partial band of the one or more partial bands based on the configuration message. The operations of  1310  may be performed according to the methods described herein. In some examples, aspects of the operations of  1310  may be performed by an antenna port selector as described with reference to  FIGS.  5  through  8   . 
     At  1315 , the UE may calculate channel state information including a linear combination of the selected one or more antenna ports for each partial band, based on receiving the configuration message. The operations of  1315  may be performed according to the methods described herein. In some examples, aspects of the operations of  1315  may be performed by a channel state information generator as described with reference to  FIGS.  5  through  8   . 
     At  1320 , the UE may transmit the channel state information including at least an indication of the selected antenna ports and linear combination coefficients for each partial band of the one or more partial bands. The operations of  1320  may be performed according to the methods described herein. In some examples, aspects of the operations of  1320  may be performed by a channel state information generator as described with reference to  FIGS.  5  through  8   . 
       FIG.  14    shows a flowchart illustrating a method  1400  that supports channel state information reporting for partial bands in accordance with aspects of the present disclosure. The operations of method  1400  may be implemented by a UE  115  or its components as described herein. For example, the operations of method  1400  may be performed by a channel state information manager as described with reference to  FIGS.  5  through  8   . In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the functions described below. Additionally or alternatively, a UE may perform aspects of the functions described below using special-purpose hardware. 
     At  1405 , the UE may receive from a base station a configuration message including an indication of one or more partial bands for channel state information reporting, where each partial band of the one or more partial bands is less than a system bandwidth and includes a set of frequency domain units associated with a precoder. The operations of  1405  may be performed according to the methods described herein. In some examples, aspects of the operations of  1405  may be performed by a configuration message processor as described with reference to  FIGS.  5  through  8   . 
     At  1410 , the UE may select one or more antenna ports for each partial band of the one or more partial bands based on the configuration message. The operations of  1410  may be performed according to the methods described herein. In some examples, aspects of the operations of  1410  may be performed by an antenna port selector as described with reference to  FIGS.  5  through  8   . 
     At  1415 , the UE may calculate channel state information including a linear combination of the selected one or more antenna ports for each partial band, based on receiving the configuration message. The operations of  1415  may be performed according to the methods described herein. In some examples, aspects of the operations of  1415  may be performed by a channel state information generator as described with reference to  FIGS.  5  through  8   . 
     At  1420 , the UE may transmit the channel state information including at least an indication of the selected antenna ports and linear combination coefficients for each partial band of the one or more partial bands. The operations of  1420  may be performed according to the methods described herein. In some examples, aspects of the operations of  1420  may be performed by a channel state information generator as described with reference to  FIGS.  5  through  8   . 
     At  1425 , the UE may the indication of one or more partial bands for channel state reporting includes one or more of a numerical quantity of partial bands for which the UE is to perform channel state measurement, or a partial band size for which the UE is to perform channel state measurement, or a ratio of partial band size to frequency domain unit size. The operations of  1425  may be performed according to the methods described herein. In some examples, aspects of the operations of  1425  may be performed by a channel state information generator as described with reference to  FIGS.  5  through  8   . 
     At  1430 , the UE may transmit to the base station a capability message indicating a numerical quality of partial bands for which the UE is capable of performing channel measurement, where the configuration message is based on the capability message. The operations of  1430  may be performed according to the methods described herein. In some examples, aspects of the operations of  1430  may be performed by a capability message generator as described with reference to  FIGS.  5  through  8   . 
       FIG.  15    shows a flowchart illustrating a method  1500  that supports channel state information reporting for partial bands in accordance with aspects of the present disclosure. The operations of method  1500  may be implemented by a base station  105  or its components as described herein. For example, the operations of method  1500  may be performed by a channel state information manager as described with reference to  FIGS.  9  through  12   . In some examples, a base station may execute a set of instructions to control the functional elements of the base station to perform the functions described below. Additionally or alternatively, a base station may perform aspects of the functions described below using special-purpose hardware. 
     At  1505 , the base station may transmit to a UE a configuration message including an indication of one or more partial bands for channel state information reporting, where each partial band of the one or more partial bands is less than a system bandwidth and includes a set of frequency domain units associated with a precoder. The operations of  1505  may be performed according to the methods described herein. In some examples, aspects of the operations of  1505  may be performed by a configuration message manager as described with reference to  FIGS.  9  through  12   . 
     At  1510 , the base station may receive channel state information including an indication of antenna ports and linear combination coefficients for each partial band of the one or more partial bands based on transmitting the configuration message and the channel state measurement. The operations of  1510  may be performed according to the methods described herein. In some examples, aspects of the operations of  1510  may be performed by an antenna port manager as described with reference to  FIGS.  9  through  12   . 
     At  1515 , the base station may communicate with the UE based on receiving the channel state information for each partial band of the one or more partial bands. The operations of  1515  may be performed according to the methods described herein. In some examples, aspects of the operations of  1515  may be performed by a communications manager as described with reference to  FIGS.  9  through  12   . 
       FIG.  16    shows a flowchart illustrating a method  1600  that supports channel state information reporting for partial bands in accordance with aspects of the present disclosure. The operations of method  1600  may be implemented by a base station  105  or its components as described herein. For example, the operations of method  1600  may be performed by a channel state information manager as described with reference to  FIGS.  9  through  12   . In some examples, a base station may execute a set of instructions to control the functional elements of the base station to perform the functions described below. Additionally or alternatively, a base station may perform aspects of the functions described below using special-purpose hardware. 
     At  1605 , the base station may transmit to a UE a configuration message including an indication of one or more partial bands for channel state information reporting, where each partial band of the one or more partial bands is less than a system bandwidth and includes a set of frequency domain units associated with a precoder. The operations of  1605  may be performed according to the methods described herein. In some examples, aspects of the operations of  1605  may be performed by a configuration message manager as described with reference to  FIGS.  9  through  12   . 
     At  1610 , the base station may receive channel state information including an indication of antenna ports and linear combination coefficients for each partial band of the one or more partial bands based on transmitting the configuration message and the channel state measurement. The operations of  1610  may be performed according to the methods described herein. In some examples, aspects of the operations of  1610  may be performed by an antenna port manager as described with reference to  FIGS.  9  through  12   . 
     At  1615 , the base station may communicate with the UE based on receiving the channel state information for each partial band of the one or more partial bands. The operations of  1615  may be performed according to the methods described herein. In some examples, aspects of the operations of  1615  may be performed by a communications manager as described with reference to  FIGS.  9  through  12   . 
     At  1620 , the base station may receive a capability message from the UE indicating a numerical quality of partial bands for which the UE is capable of performing channel measurement, where the configuration message is based on the capability message. The operations of  1620  may be performed according to the methods described herein. In some examples, aspects of the operations of  1620  may be performed by a capability message manager as described with reference to  FIGS.  9  through  12   . 
     It should be noted that the methods described herein describe possible implementations, and that the operations and the steps may be rearranged or otherwise modified and that other implementations are possible. Further, aspects from two or more of the methods may be combined. 
     Although aspects of an LTE, LTE-A, LTE-A Pro, or NR system may be described for purposes of example, and LTE, LTE-A, LTE-A Pro, or NR terminology may be used in much of the description, the techniques described herein are applicable beyond LTE, LTE-A, LTE-A Pro, or NR networks. For example, the described techniques may be applicable to various other wireless communications systems such as Ultra Mobile Broadband (UMB), Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM, as well as other systems and radio technologies not explicitly mentioned herein. 
     Information and signals described herein may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof. 
     The various illustrative blocks and components described in connection with the disclosure herein may be implemented or performed with a general-purpose processor, a DSP, an ASIC, a CPU, an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration). 
     The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Other examples and implementations are within the scope of the disclosure and appended claims. For example, due to the nature of software, functions described herein may be implemented using software executed by a processor, hardware, firmware, hardwiring, or combinations of any of these. Features implementing functions may also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations. 
     Computer-readable media includes both non-transitory computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A non-transitory storage medium may be any available medium that may be accessed by a general-purpose or special purpose computer. By way of example, and not limitation, non-transitory computer-readable media may include random-access memory (RAM), read-only memory (ROM), electrically erasable programmable ROM (EEPROM), flash memory, compact disk (CD) ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that may be used to carry or store desired program code means in the form of instructions or data structures and that may be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of computer-readable medium. Disk and disc, as used herein, include CD, laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above are also included within the scope of computer-readable media. 
     As used herein, including in the claims, “or” as used in a list of items (e.g., a list of items prefaced by a phrase such as “at least one of” or “one or more of”) indicates an inclusive list such that, for example, a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Also, as used herein, the phrase “based on” shall not be construed as a reference to a closed set of conditions. For example, an example step that is described as “based on condition A” may be based on both a condition A and a condition B without departing from the scope of the present disclosure. In other words, as used herein, the phrase “based on” shall be construed in the same manner as the phrase “based at least in part on.” 
     In the appended figures, similar components or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If just the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label, or other subsequent reference label. 
     The description set forth herein, in connection with the appended drawings, describes example configurations and does not represent all the examples that may be implemented or that are within the scope of the claims. The term “example” used herein means “serving as an example, instance, or illustration,” and not “preferred” or “advantageous over other examples.” The detailed description includes specific details for the purpose of providing an understanding of the described techniques. These techniques, however, may be practiced without these specific details. In some instances, known structures and devices are shown in block diagram form in order to avoid obscuring the concepts of the described examples. 
     The description herein is provided to enable a person having ordinary skill in the art to make or use the disclosure. Various modifications to the disclosure will be apparent to a person having ordinary skill in the art, and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not limited to the examples and designs described herein, but is to be accorded the broadest scope consistent with the principles and novel features disclosed herein.