Patent Publication Number: US-2023147146-A1

Title: Reference signal for cross-link interference measurement

Description:
CROSS REFERENCE 
     The present application is a 371 national stage filing of International PCT Application No. PCT/CN2020/089419 by REN et al. entitled “REFERENCE SIGNAL FOR CROSS-LINK INTERFERENCE MEASUREMENT,” filed May 9, 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 reference signals for cross-link interference (CLI) measurement. 
     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). 
     One or more UEs may be served by separate cells, including separate serving base stations. In some instances, the UEs served by different cells may have different timing, such that one UE may be receiving signals while another UE is transmitting signals. In some cases, UEs may have different timing even when served by the same cell. When the UEs are close together, the UEs may be able to detect signals transmitted by each other. One UE may experience cross-link interference (CLI) caused by the other UE due to conflicting slot configurations. 
     SUMMARY 
     The described techniques relate to improved methods, systems, devices, and apparatuses that support reference signals for cross-link interference (CLI) measurement. Generally, the described techniques provide for CLI measurement by a first user equipment (UE). A first UE may communicate with a base station to measure cross-link interference (CLI) from an aggressor UE. The first UE may receive, from a base station, a CLI measurement configuration which provides a CLI measurement resource for the first UE to use for measurement of CLI from an aggressor UE. The first UE may select, based on a selection priority, a reference cell for estimation of a CLI measurement resource timing. The first UE may determine a reference cell timing based on a reference signal of the reference cell, and the first UE may estimate the CLI measurement resource timing based on the reference cell timing. The first UE may measure CLI from the aggressor UE in accordance with the CLI measurement resource timing. 
     In some cases, the base station may transmit, to the first UE, and indication of a reference cell to be used by the first UE for estimation of a CLI measurement resource timing, In some cases, the base station may receive, from the first UE, a CLI report from the first UE which may include one or more CLI measurement made by the first UE on the CLI measurement resource in accordance with the CLI measurement resource timing. 
     A method of wireless communications at a first UE is described. The method may include receiving a CLI measurement configuration which provides a CLI measurement resource for the UE for measurement of CLI from an aggressor UE, selecting, based on a selection priority, a reference cell for estimation of a CLI measurement resource timing, determining a reference cell timing based on a reference signal of the reference cell, estimating the CLI measurement resource timing based on the reference cell timing, and measuring CLI from the aggressor UE in accordance with the CLI measurement resource timing. 
     An apparatus for wireless communications at a first 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 a CLI measurement configuration which provides a CLI measurement resource for the UE for measurement of CLI from an aggressor UE, select, based on a selection priority, a reference cell for estimation of a CLI measurement resource timing, determine a reference cell timing based on a reference signal of the reference cell, estimate the CLI measurement resource timing based on the reference cell timing, and measure CLI from the aggressor UE in accordance with the CLI measurement resource timing. 
     Another apparatus for wireless communications at a first UE is described. The apparatus may include means for receiving a CLI measurement configuration which provides a CLI measurement resource for the UE for measurement of CLI from an aggressor UE, selecting, based on a selection priority, a reference cell for estimation of a CLI measurement resource timing, determining a reference cell timing based on a reference signal of the reference cell, estimating the CLI measurement resource timing based on the reference cell timing, and measuring CLI from the aggressor UE in accordance with the CLI measurement resource timing. 
     A non-transitory computer-readable medium storing code for wireless communications at a first UE is described. The code may include instructions executable by a processor to receive a CLI measurement configuration which provides a CLI measurement resource for the UE for measurement of CLI from an aggressor UE, select, based on a selection priority, a reference cell for estimation of a CLI measurement resource timing, determine a reference cell timing based on a reference signal of the reference cell, estimate the CLI measurement resource timing based on the reference cell timing, and measure CLI from the aggressor UE in accordance with the CLI measurement resource timing. 
     In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, selecting the reference cell may include operations, features, means, or instructions for receiving, with the CLI measurement configuration, an indication that the reference cell may be a serving cell of the aggressor UE, and selecting the serving cell of the aggressor UE as the reference cell based on the selection priority. 
     In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the indication includes a SSB index corresponding to the serving cell of the aggressor UE, a CSI-RS index corresponding to the serving cell of the aggressor UE, or both. 
     In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, determining the reference cell timing may include operations, features, means, or instructions for using the SSB index or the CSI-RS index as the reference signal from which the reference cell timing may be determined. 
     Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for identifying a frequency offset of the CLI measurement resource, based on measurements of the reference signal. 
     Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for applying a frequency correction corresponding to the identified frequency offset in the CLI measurement resource. 
     In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, selecting the reference cell may include operations, features, means, or instructions for identifying a reference serving cell configured for estimation of the CLI measurement resource timing, and selecting the reference serving cell as the reference cell based on the selection priority, where the selection priority may be that the UE selects the reference serving cell when the CLI measurement configuration does not identify the reference cell as a serving cell of the aggressor UE. 
     In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, determining the reference cell timing may include operations, features, means, or instructions for using a SSB or a CSI-RS of the reference serving cell to determine the reference cell timing. 
     In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, selecting the reference cell may include operations, features, means, or instructions for selecting a serving cell of the UE as the reference cell based on the selection priority, where the selection priority may be that the UE selects the serving cell of the UE when the CLI measurement configuration does not identify the reference cell as a serving cell of the aggressor UE, and when no reference serving cell may have been configured. 
     A method of wireless communications at a base station is described. The method may include transmitting, to a first UE, a CLI measurement configuration which provides a CLI measurement resource for measurement by the first UE of CLI from an aggressor UE, transmitting, to the first UE, an indication of a reference cell to be used by the first UE for estimation of a CLI measurement resource timing, and receiving a CLI report from the first UE which includes one or more CLI measurements made by the first UE on the CLI measurement resource and in accordance with the CLI measurement resource timing. 
     An apparatus for wireless communications at a base station 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 first UE, a CLI measurement configuration which provides a CLI measurement resource for measurement by the first UE of CLI from an aggressor UE, transmit, to the first UE, an indication of a reference cell to be used by the first UE for estimation of a CLI measurement resource timing, and receive a CLI report from the first UE which includes one or more CLI measurements made by the first UE on the CLI measurement resource and in accordance with the CLI measurement resource timing. 
     Another apparatus for wireless communications at a base station is described. The apparatus may include means for transmitting, to a first UE, a CLI measurement configuration which provides a CLI measurement resource for measurement by the first UE of CLI from an aggressor UE, transmitting, to the first UE, an indication of a reference cell to be used by the first UE for estimation of a CLI measurement resource timing, and receiving a CLI report from the first UE which includes one or more CLI measurements made by the first UE on the CLI measurement resource and in accordance with the CLI measurement resource timing. 
     A non-transitory computer-readable medium storing code for wireless communications at a base station is described. The code may include instructions executable by a processor to transmit, to a first UE, a CLI measurement configuration which provides a CLI measurement resource for measurement by the first UE of CLI from an aggressor UE, transmit, to the first UE, an indication of a reference cell to be used by the first UE for estimation of a CLI measurement resource timing, and receive a CLI report from the first UE which includes one or more CLI measurements made by the first UE on the CLI measurement resource and in accordance with the CLI measurement resource timing. 
     In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, transmitting the indication of the reference cell may include operations, features, means, or instructions for indicating, with the CLI measurement configuration, that the reference cell may be a serving cell of the aggressor UE. 
     In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the indication includes a SSB index corresponding to the serving cell of the aggressor UE, a CSI-RS index corresponding to the serving cell of the aggressor UE, or both. 
     In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, transmitting the indication of the reference cell may include operations, features, means, or instructions for indicating, to the first UE, an identifier of a reference serving cell, where the reference serving cell may be different from a serving cell of the aggressor UE. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    illustrates an example of a wireless communications system that supports reference signals for cross-link interference (CLI) measurement in accordance with aspects of the present disclosure. 
         FIG.  2    illustrates an example of a wireless communications system that supports reference signals for CLI measurement in accordance with aspects of the present disclosure. 
         FIG.  3    illustrates an example of a process flow that supports reference signals for CLI measurement in accordance with aspects of the present disclosure. 
         FIGS.  4  and  5    show block diagrams of devices that support reference signals for CLI measurement in accordance with aspects of the present disclosure. 
         FIG.  6    shows a block diagram of a communications manager that supports reference signals for CLI measurement in accordance with aspects of the present disclosure. 
         FIG.  7    shows a diagram of a system including a device that supports reference signals for CLI measurement in accordance with aspects of the present disclosure. 
         FIGS.  8  and  9    show block diagrams of devices that support reference signals for CLI measurement in accordance with aspects of the present disclosure. 
         FIG.  10    shows a block diagram of a communications manager that supports reference signals for CLI measurement in accordance with aspects of the present disclosure. 
         FIG.  11    shows a diagram of a system including a device that supports reference signals for CLI measurement in accordance with aspects of the present disclosure. 
         FIGS.  12  through  16    show flowcharts illustrating methods that support reference signals for CLI measurement in accordance with aspects of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     A first user equipment (UE) may be served by a first serving base station in a first serving cell. The serving base station may serve one or more UEs within a coverage area. Another serving cell may be near to or partially overlapping in space with the first serving cell. The second serving cell may include a second serving base station serving one or more UEs in a second coverage area. One of the UEs in the second serving cell may be nearby to one of the UEs in the first serving cell. The UEs may be able to detect transmissions by other UEs. 
     One of the UEs in the second serving cell may have an uplink/downlink slot format. This uplink/downlink slot format may conflict with the uplink/downlink slot format of the nearby UE in the first serving cell. For example, the second UE may be configured to transmit uplink transmissions in the same slot or slot in which the first UE is configured to receive downlink transmissions. Thus, the uplink transmissions by the second UE may interfere with downlink receptions at the first UE. This may be an example of cross-link interference (CLI), where the second UE is an aggressor UE and the first UE is a victim UE. CLI may occur in cases of time division duplexing (TDD) systems. While described above as occurring between UEs being served by different cells, CLI may also arise between UEs of a same cell, as long as the uplink/downlink slot format of the UEs differ. 
     The network may configure the first UE with a CLI measurement configuration, so that the victim UE may perform interference management. The victim UE may receive third layer measurement and reporting mechanisms for the CLI measurement. The CLI measurement may include measurements of sounding reference signals (SRSs), or reference signal received power (RSRP) measurement. The measurement resource configuration may also include periodicity, frequency, and resource blocks or orthogonal frequency division multiplexing (OFDM) symbols on which the victim UE is to measure the CLI. The CLI may correspond to a transmission of an uplink reference signal, such as the SRS, or an uplink channel by the aggressor UE. The aggressor UE may use a transmit beam (e.g., a spatial filter for transmission) to transmit the uplink signal, where the transmit beam is the same as the receive beam that the aggressor UE uses to receive downlink signals from the base station. 
     There may be timing differences between the slot configuration of the victim UE and the slot configuration of the aggressor UE. The victim UE may not need to be aware of the slot configuration of the aggressor UE. In order to measure the CLI, the victim UE may follow the measurement resource configuration received from the network. 
     However, the measurement resource configuration may not include an indication of a synchronization signal block (SSB) index, channel state information reference signal (CSI-RS) index, or another indication, of the beam for the victim UE to use to perform the CLI measurement. For example, the victim UE may use the same beam that it receive the CLI measurement configuration indication on to perform the CLI measurement. The beam may not be the beam on which the victim UE detects the highest amount of CLI from the aggressor UE. 
     However, in order to track the CLI measurement resource, CLI measurement may improve if the victim UE receives an indication of an associated SSB index or CSI-RS index of the CLI measurement resource. The UE may also determine an associated SSB or CSI-RS to use for the CLI measurement resource. The SSB or CSI-RS may indicate a particular reference cell to use to determine reference timing and frequency for the CLI measurement resource. 
     The victim UE may determine which reference cell to use based on a hierarchical selection priority process. The UE may receive and indication of a SSB or CSI-RS corresponding to the serving cell of the aggressor UE. The UE may also receive an indication of a SSB or a CSI-RS corresponding to a reference cell, where the reference cell does not serve the aggressor UE or the victim UE. Or, the UE may determine a reference serving cell to use. If the UE does not receive an indication of the serving cell of the aggressor UE or the reference serving cell, the victim may use a SSB or CSI-RS of its own serving cell to track the CLI measurement resource to perform the CLI measurement. 
     Thus, the victim UE may estimate a timing and frequency offset of a CLI transmission. The victim UE may determine timing and frequency offset information of the CLI transmission based on information conveyed by or determined from an indicated SSB or CSI-RS. The victim UE may be able to perform CLI measurement resource tracking, and improve CLI measurement. 
     Aspects of the disclosure are initially described in the context of wireless communications systems. Aspects of the disclosure are then described with respect to 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 reference signals for CLI measurement. 
       FIG.  1    illustrates an example of a wireless communications system  100  that supports reference signals for CLI measurement 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. 
     A UE  115  may communicate with a base station  105  to measure CLI from an aggressor UE  115 . The first UE  115  may be served by a base station  105  in a first cell, and the aggressor UE  115  may be served by a different base station  105  in a different cell. The first UE  105  may receive, from the serving base station  105 , a CLI measurement configuration which provides a CLI measurement resource for the first UE  115  to use for measurement of CLI from the aggressor UE  115 . The first UE  115  may select, based on a selection priority, a reference cell for estimation of a CLI measurement resource timing. The reference cell may correspond to the serving cell of the aggressor UE  115 , a separate reference cell, or the reference cell may be the serving cell of the first UE  115 . The first UE  115  may determine a reference cell timing based on a reference signal of the reference cell, and the first UE  115  may estimate the CLI measurement resource timing based on the reference cell timing. The first UE  115  may measure CLI from the aggressor UE  115  in accordance with the CLI measurement resource timing. 
     In some cases, the base station  105  may transmit, to the first UE  115 , and indication of a reference cell to be used by the first UE  115  for estimation of a CLI measurement resource timing, In some cases, the base station  105  may receive, from the first UE, a CLI report from the first UE which may include one or more CLI measurement made by the first UE on the CLI measurement resource in accordance with the CLI measurement resource timing. 
       FIG.  2    illustrates an example of a wireless communications system  200  that supports reference signals for CLI measurement in accordance with aspects of the present disclosure. In some examples, wireless communications system  200  may implement aspects of wireless communication system  100 . Wireless communications system  200  may include UEs  115 - a  and  115 - b , which may be examples of UEs  115  as described with reference to  FIG.  1   . Wireless communications system  200  also includes base stations  105 - a ,  105 - b , and  105 - c , which may be examples of base stations  105  as described with reference to  FIG.  1   . UE  115 - a  may be served by a first cell, which may include serving base station  105 - a , where base station  105 - a  serves coverage area  110 - a . UE  115 - b  may be served by a second cell, which may include serving bae station  105 - b , where base station  105 - b  serves coverage area  110 - b . Base station  105 - c  may also serve another serving cell. 
     UE  115 - a  may communicate with base station  105 - a  by transmitting and receiving signals on beams  210 - a ,  210 - b , and  210 - c . Base station  105 - a  may communicate with UE  115 - a  using beams  205 - a ,  205 - b , and  205 - c.    
     UE  115 - b  may communicate with base station  105 - b  by transmitting and receiving signals on beams  210 - d ,  210 - e , and  210 - f . Base station  105 - a  may communicate with UE  115 - a  using beams  205 - d ,  205 - e , and  205 - f . Another base station  105 - c  may serve other UEs  115 , and base station  105 - c  may communicate using beams  205 - g ,  205 - h , and  205 - i . Each beam may correspond to a spatial filter. The network may provide spatial relation information between SRSs transmitted on a beam and SSB indices and CSI-RS indices. Thus, a SSB index or a CSI-RS index, or both, may correspond to particular beams in a cell. 
     UE  115 - a  and UE  115 - b  may be close in proximity, and may have conflicting slot configurations. For example, UE  115 - b  may transmit uplink messages during one or more slots in which UE  115 - a  is configured to receive downlink transmissions from base station  105 - a . The uplink transmissions may include SRS, physical uplink control channel (PUCCH) transmissions, physical uplink shared channel (PUSCH) transmission, physical random access channel (PRACH) transmissions, and other uplink transmissions. UE  115 - a  may therefore experience CLI caused by UE  115 - b . UE  115 - a  may be a victim UE to UE  115 - b , which may be an aggressor UE. A PUCCH transmission by UE  115 - b , for example, may be based on a spatial relationship between the PUCCH and a SSB or CSI-RS. UE  115 - b  may transmit the PUCCH (or other uplink signal) with the same spatial filter (e.g., beam  210 ) as for the reception of the same SSB or CSI-RS. 
     UE  115 - a  may use a different receive beam (e.g., beam  210 - b ) to receive a CSI-RS or SSB configuration information from base station  105 - a  about a CLI measurement resource for measuring CLI from an uplink transmission by aggressor UE  115 - b  (e.g., on beam  210 - f ). Beam  210 - b  may not have beam correspondence to beam  210 - f . Thus, accuracy and efficiency of CLI measurement resource tracking by UE  115 - a  may be improved by UE  115 - a  being aware of a particular SSB or CSI-RS associated with the CLI measurement resource. 
     Base station  105 - a  may transmit CLI measurement configuration  215  to UE  115 - a . CLI measurement configuration may include an indication of a particular CLI measurement resource for UE  115 - a  to use to measure CLI caused by UE  115 - b . Based on CLI measurement configuration  215 , UE  115 - a  may select a reference cell to use for estimation of the CLI measurement resource timing. UE  115 - a  may select the reference cell based on a selection priority, in order to improve CLI measurement resource tracking and measurement. The selection priority may include a hierarchy of which reference cell may be prioritized to be selected by UE  115 - a  to use for CLI measurement resource tracking. 
     The first priority of UE  115 - a  may be to select the aggressor cell of the aggressor UE  115 - b  as the reference cell to use for estimation timing. In some cases, CLI measurement configuration  215  may include a serving cell index indicating the aggressor cell (e.g., the cell corresponding to base station  105 - b  and coverage areas  110 - b ). If UE  115 - a  receives this indication, UE  115 - a  may select the aggressor cell as the reference to determine a reference cell timing. The serving cell index may be a SSB index or a CSI-RS index, or both. In some cases, UE  115 - a  and UE  115 - b  are in the same serving cell, and thus the aggressor cell also serves UE  115 - a . In this cases, UE  115 - a  is already aware of the SSB index and CSI-RS index of the serving cell, and may use these to determine the CLI measurement resource timing. 
     In this case, UE  115 - a  may use the SSB index or the CSI-RS index as a reference signal. UE  115 - a  may determine a reference cell timing based on the reference signal. UE  115 - a  may track the CLI measurement resource based on the reference signal. The CLI transmission timing may be approximated by: T CLI =T UL2 +T DL2 −T DL1  UE  115 - a  may obtain the system timing of base station  105 - a  based on downlink timing T DL2  of a signal received from base station  105 - a , and the configured uplink timing T UL2  UE  115 - a  is configured to use for transmitting uplink signals to base station  105 - a . UE  115 - a  may obtain downlink timing T DL1  of the aggressor cell based on the receive SSB or CSI-RS indicated in CLI measurement configuration  215 . Thus, UE  115 - a  may determine transmission timing T CLI  of the CLI transmission. UE  115 - a  may use the transmission timing T CLI  to track and measure CLI measurement resource. 
     In some cases, UE  115 - a  may also identify a frequency offset of the CLI measurement resource, based on measurements of the reference signal. UE  115 - a  may obtain the frequency offset of a downlink signal of UE  115 - b  based on the SSB index or CSI-RS index (or both) indicated in CLI measurement configuration  215 . In some cases, aggressor UE  115 - b  may compensate for this frequency offset in uplink transmissions by UE  115 - b . UE  115 - a  may then apply a frequency correction corresponding to the identified or estimated frequency offset in the CLI measurement resource. UE  115 - a  may then measure CLI interference from UE  115 - b  in accordance with the estimated CLI measurement resource timing. 
     The second priority of UE  115 - a  may be to select a reference serving cell, where reference serving cell does not serve aggressor UE  115 - b  or victim UE  115 - a . In some cases, CLI measurement configuration  215  may include a serving cell index indicating the reference serving cell (e.g., the serving cell corresponding to base station  105 - c ). Or, UE  115 - a  may identify reference serving cell and base station  105 - c  based on other configuration signaling. The serving cell index may be a SSB index or a CSI-RS index, or both. UE  115 - a  may select the reference serving cell as the reference cell. UE  115 - a  may then use the SSB index or the CSI-RS index of the reference serving cell to determine the reference cell timing. UE  115 - a  may use the reference cell timing to estimate the CLI measurement resource timing, and UE  115 - a  may measure CLI interference from aggressor UE  115 - b  in accordance with the CLI measurement resource timing. 
     The third priority of UE  115 - a  may be to select the serving cell of UE  115 - a  as the reference cell. UE  115 - a  may select the serving cell of UE  115 - a  if UE  115 - a  does not receive serving cell index of the aggressor serving cell corresponding to base station  105 - b , or receive or determine a serving cell index of the reference serving cell corresponding to base station  105 - c . UE  115 - a  may then use reference cell timing of its own serving cell based on a reference signal of the cell. UE  115 - a  may estimate the CLI measurement resource timing, and perform the CLI measurement of the CLI caused by UE  115 - b.    
     In some cases, UE  115 - a  may transmit a CLI report to base station  105 - a  which includes one or more CLI measurement made by UE  115 - a  of the CLI resource in accordance with the CLI measurement resource timing. 
       FIG.  3    illustrates an example of a process flow  300  that supports reference signals for CLI measurement in accordance with aspects of the present disclosure. In some examples, process flow  300  may implement aspects of wireless communication systems  100  and  200 . Process flow  300  may include UE  115 - c , which may be an example of a UE  115  as described with reference to  FIG.  1   , UE  115 - a  as described with reference to  FIG.  2   . Process flow  300  may also include base station  105 - d , which may be an example of a base station  105  as described with reference to  FIG.  1   , and base station  105 - a  as described with reference to  FIG.  2   . UE  115 - c  and base station  105 - d  may communicate to estimate and measure CLI from an aggressor UE  115 . 
     At  305 , UE  115 - c  may receive, from base station  105 - d , a CLI measurement configuration which provides a CLI measurement resource for UE  115 - c  for measurement of CLI interference from an aggressor UE  115 . 
     In some cases, at  310 , UE  115 - c  may receive, from base station  105 - d , and along with the CLI measurement configuration at  305 , an indication that the reference cell is a serving cell of the aggressor UE  115 . The indication may include a SSB index corresponding to the serving cell of the aggressor UE  115 , a CSI-RS corresponding to the serving cell of the aggressor UE  115 , or both. 
     At  315 , UE  115 - c  may select, based on a selection priority, a reference cell for estimation of a CLI measurement resource timing. In cases where UE  115 - c  receives at  310  and indication that the reference cell is a serving cell of the aggressor UE  115 , UE  115 - c  may select the serving cell of the aggressor UE  115  as the reference cell based on the selection priority. 
     In some cases, UE  115 - c  may identify a reference serving cell configured for estimation of the CLI measurement resource timing. In some cases, base station  105 - c  ay indicate to UE  115 - c , and identifier of the reference serving cell, where the reference serving cell is different from a serving cell of the aggressor UE  115 . UE  115 - c  may select the reference serving cell as the reference cell based on the selection priority, where the selection priority is that UE  115 - c  selects the reference serving cell when the CLI measurement configuration, at  305 , does not identify the reference cell as the serving cell of the aggressor UE  115  at. 
     In other cases, UE  115 - c  may select a serving cell of UE  115 - c  as the reference cell based on the selection priority, where the selection priority is that UE  115 - c  selects the serving cell of UE  115 - c  when the CLI measurement configuration does not identify the reference cell as a serving cell of the aggressor UE  115 , and when no reference serving cell has been configured (e.g., UE  115 - c  does not identify a reference serving cell). 
     At  320 , UE  115 - c  may determine a reference cell timing based on a reference signal of the reference cell. In cases where UE  115 - c  selects, at  315 , the reference cell of the aggressor UE  115  as the reference cell, UE  115 - c  may use the SSB index or the CSI-RS index as the reference signal from which the reference cell timing is determined. In cases where UE  115 - c  selects the reference serving cell as the reference cell, UE  115 - c  may use a SSB index or a CSI-RS index of the reference serving cell to determine the reference cell timing. 
     At  325 , UE  115 - c  may estimate the CLI measurement resource timing based on the reference cell timing. In some cases, UE  115 - c  may identify a frequency offset of the CLI measurement resource, based on measurement of the reference cell. UE  115 - c  may apply a frequency correction corresponding to the identified frequency offset in the CLI measurement resource. 
     At  330 , UE  115 - c  may measure CLI from the aggressor UE  115  in accordance with the CLI measurement resource timing. In some cases, at  335 , base station  105 - d  may receive a CLI report from UE  115 - c , which includes one or more CLI measurements may by UE  115 - c  on the CLI measurement resource and in accordance with the CLI measurement resource timing. 
       FIG.  4    shows a block diagram  400  of a device  405  that supports reference signals for CLI measurement in accordance with aspects of the present disclosure. The device  405  may be an example of aspects of a UE  115  as described herein. The device  405  may include a receiver  410 , a communications manager  415 , and a transmitter  420 . The device  405  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  410  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 reference signals for CLI measurement, etc.). Information may be passed on to other components of the device  405 . The receiver  410  may be an example of aspects of the transceiver  720  described with reference to  FIG.  7   . The receiver  410  may utilize a single antenna or a set of antennas. 
     The communications manager  415  may receive a CLI measurement configuration which provides a CLI measurement resource for the UE for measurement of CLI from an aggressor UE, select, based on a selection priority, a reference cell for estimation of a CLI measurement resource timing, determine a reference cell timing based on a reference signal of the reference cell, estimate the CLI measurement resource timing based on the reference cell timing, and measure CLI from the aggressor UE in accordance with the CLI measurement resource timing. The communications manager  415  may be an example of aspects of the communications manager  710  described herein. 
     The communications manager  415 , 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 communications manager  415 , 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 communications manager  415 , 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 communications manager  415 , or its sub-components, may be a separate and distinct component in accordance with various aspects of the present disclosure. In some examples, the communications manager  415 , 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  420  may transmit signals generated by other components of the device  405 . In some examples, the transmitter  420  may be collocated with a receiver  410  in a transceiver module. For example, the transmitter  420  may be an example of aspects of the transceiver  720  described with reference to  FIG.  7   . The transmitter  420  may utilize a single antenna or a set of antennas. 
     In some examples, the communications manager  415  described herein may be implemented as a chipset of a wireless modem, and the receiver  410  and the transmitter  420  may be implemented as sets of analog components (e.g., amplifiers, filters, phase shifters, antennas, etc.) The wireless modem may obtain and decode signals from the receiver  410  over a receive interface, and may output signals for transmission to the transmitter  420  over a transmit interface. 
     The actions performed by the communications manager  415  as describer herein may be implemented to realize one or more potential advantages. One implementation may allow a UE  115  to improve communications efficiency with improve CLI tracking and measurement. Improved CLI tracking may improve accuracy of CLI measurements, therefore improving accuracy of communications adjustments by the network. 
       FIG.  5    shows a block diagram  500  of a device  505  that supports reference signals for CLI measurement in accordance with aspects of the present disclosure. The device  505  may be an example of aspects of a device  405 , or a UE  115  as described herein. The device  505  may include a receiver  510 , a communications manager  515 , and a transmitter  545 . 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 reference signals for CLI measurement, 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  720  described with reference to  FIG.  7   . The receiver  510  may utilize a single antenna or a set of antennas. 
     The communications manager  515  may be an example of aspects of the communications manager  415  as described herein. The communications manager  515  may include a measurement configuration component  520 , a reference cell selection component  525 , a reference cell timing component  530 , a resource timing component  535 , and an interference measurement component  540 . The communications manager  515  may be an example of aspects of the communications manager  710  described herein. 
     The measurement configuration component  520  may receive a CLI measurement configuration which provides a CLI measurement resource for the UE for measurement of CLI from an aggressor UE. 
     The reference cell selection component  525  may select, based on a selection priority, a reference cell for estimation of a CLI measurement resource timing. 
     The reference cell timing component  530  may determine a reference cell timing based on a reference signal of the reference cell. 
     The resource timing component  535  may estimate the CLI measurement resource timing based on the reference cell timing. 
     The interference measurement component  540  may measure CLI from the aggressor UE in accordance with the CLI measurement resource timing. 
     The transmitter  545  may transmit signals generated by other components of the device  505 . In some examples, the transmitter  545  may be collocated with a receiver  510  in a transceiver module. For example, the transmitter  545  may be an example of aspects of the transceiver  720  described with reference to  FIG.  7   . The transmitter  545  may utilize a single antenna or a set of antennas. 
     A process of a UE  115  (e.g., controlling the receiver  510 , the transmitter  545 , or the transceiver  720  as described with reference to  FIG.  7   ) may operate the components described herein to improve communications accuracy at the UE  115 . The processor of the UE  115  may operate the receiver  510  to receive an indication of a CLI measurement configuration, which the processor of the UE  115  may use to measure CLI effectively. The processor of the UE  115  may select a reference cell for estimation of CLI resource timing, determine reference cell timing, estimate the CLI measurement resource, and measure the CLI measurement resource, based on the receive CLI measurement configuration. The processor of the UE  115  may therefore improve CLI measurement resource tracking, improving accuracy of CLI measurement. Improved accuracy of CLI measurement may improve overall communications at the UE  115 , by providing measurements that may be used by the network to decrease interference at the UE  115 . 
       FIG.  6    shows a block diagram  600  of a communications manager  605  that supports reference signals for CLI measurement in accordance with aspects of the present disclosure. The communications manager  605  may be an example of aspects of a communications manager  415 , a communications manager  515 , or a communications manager  710  described herein. The communications manager  605  may include a measurement configuration component  610 , a reference cell selection component  615 , a reference cell timing component  620 , a resource timing component  625 , an interference measurement component  630 , a reference cell indication component  635 , a frequency identification component  640 , and a frequency correction component  645 . Each of these modules may communicate, directly or indirectly, with one another (e.g., via one or more buses). 
     The measurement configuration component  610  may receive a CLI measurement configuration which provides a CLI measurement resource for the UE for measurement of CLI from an aggressor UE. 
     The reference cell selection component  615  may select, based on a selection priority, a reference cell for estimation of a CLI measurement resource timing. In some examples, the reference cell selection component  615  may select the serving cell of the aggressor UE as the reference cell based on the selection priority. In some examples, the reference cell selection component  615  may identify a reference serving cell configured for estimation of the CLI measurement resource timing. 
     In some examples, the reference cell selection component  615  may select the reference serving cell as the reference cell based on the selection priority, where the selection priority is that the UE selects the reference serving cell when the CLI measurement configuration does not identify the reference cell as a serving cell of the aggressor UE. In some examples, the reference cell selection component  615  may select a serving cell of the UE as the reference cell based on the selection priority, where the selection priority is that the UE selects the serving cell of the UE when the CLI measurement configuration does not identify the reference cell as a serving cell of the aggressor UE, and when no reference serving cell has been configured. 
     The reference cell timing component  620  may determine a reference cell timing based on a reference signal of the reference cell. In some examples, the reference cell timing component  620  may use the SSB index or the CSI-RS index as the reference signal from which the reference cell timing is determined. In some examples, the reference cell timing component  620  may use a SSB or a CSI-RS of the reference serving cell to determine the reference cell timing. The resource timing component  625  may estimate the CLI measurement resource timing based on the reference cell timing. 
     The interference measurement component  630  may measure CLI from the aggressor UE in accordance with the CLI measurement resource timing. 
     The reference cell indication component  635  may receive, with the CLI measurement configuration, an indication that the reference cell is a serving cell of the aggressor UE. 
     In some cases, the indication includes a SSB index corresponding to the serving cell of the aggressor UE, a CSI-RS index corresponding to the serving cell of the aggressor UE, or both. 
     The frequency identification component  640  may identify a frequency offset of the CLI measurement resource, based on measurements of the reference signal. 
     The frequency correction component  645  may apply a frequency correction corresponding to the identified frequency offset in the CLI measurement resource. 
       FIG.  7    shows a diagram of a system  700  including a device  705  that supports reference signals for CLI measurement in accordance with aspects of the present disclosure. The device  705  may be an example of or include the components of device  405 , device  505 , or a UE  115  as described herein. The device  705  may include components for bi-directional voice and data communications including components for transmitting and receiving communications, including a communications manager  710 , an I/O controller  715 , a transceiver  720 , an antenna  725 , memory  730 , and a processor  740 . These components may be in electronic communication via one or more buses (e.g., bus  745 ). 
     The communications manager  710  may receive a CLI measurement configuration which provides a CLI measurement resource for the UE for measurement of CLI from an aggressor UE, select, based on a selection priority, a reference cell for estimation of a CLI measurement resource timing, determine a reference cell timing based on a reference signal of the reference cell, estimate the CLI measurement resource timing based on the reference cell timing, and measure CLI from the aggressor UE in accordance with the CLI measurement resource timing. 
     The I/O controller  715  may manage input and output signals for the device  705 . The I/O controller  715  may also manage peripherals not integrated into the device  705 . In some cases, the I/O controller  715  may represent a physical connection or port to an external peripheral. In some cases, the I/O controller  715  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  715  may represent or interact with a modem, a keyboard, a mouse, a touchscreen, or a similar device. In some cases, the I/O controller  715  may be implemented as part of a processor. In some cases, a user may interact with the device  705  via the I/O controller  715  or via hardware components controlled by the I/O controller  715 . 
     The transceiver  720  may communicate bi-directionally, via one or more antennas, wired, or wireless links as described above. For example, the transceiver  720  may represent a wireless transceiver and may communicate bi-directionally with another wireless transceiver. The transceiver  720  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  725 . However, in some cases the device may have more than one antenna  725 , which may be capable of concurrently transmitting or receiving multiple wireless transmissions. 
     The memory  730  may include RAM and ROM. The memory  730  may store computer-readable, computer-executable code  735  including instructions that, when executed, cause the processor to perform various functions described herein. In some cases, the memory  730  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  740  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  740  may be configured to operate a memory array using a memory controller. In other cases, a memory controller may be integrated into the processor  740 . The processor  740  may be configured to execute computer-readable instructions stored in a memory (e.g., the memory  730 ) to cause the device  705  to perform various functions (e.g., functions or tasks supporting reference signals for CLI measurement). 
     The code  735  may include instructions to implement aspects of the present disclosure, including instructions to support wireless communications. The code  735  may be stored in a non-transitory computer-readable medium such as system memory or other type of memory. In some cases, the code  735  may not be directly executable by the processor  740  but may cause a computer (e.g., when compiled and executed) to perform functions described herein. 
       FIG.  8    shows a block diagram  800  of a device  805  that supports reference signals for CLI measurement in accordance with aspects of the present disclosure. The device  805  may be an example of aspects of a base station  105  as described herein. The device  805  may include a receiver  810 , a communications manager  815 , and a transmitter  820 . The device  805  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  810  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 reference signals for CLI measurement, etc.). Information may be passed on to other components of the device  805 . The receiver  810  may be an example of aspects of the transceiver  1120  described with reference to  FIG.  11   . The receiver  810  may utilize a single antenna or a set of antennas. 
     The communications manager  815  may transmit, to a first UE, a CLI measurement configuration which provides a CLI measurement resource for measurement by the first UE of CLI from an aggressor UE, transmit, to the first UE, an indication of a reference cell to be used by the first UE for estimation of a CLI measurement resource timing, and receive a CLI report from the first UE which includes one or more CLI measurements made by the first UE on the CLI measurement resource and in accordance with the CLI measurement resource timing. The communications manager  815  may be an example of aspects of the communications manager  1110  described herein. 
     The communications manager  815 , 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 communications manager  815 , 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 communications manager  815 , 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 communications manager  815 , or its sub-components, may be a separate and distinct component in accordance with various aspects of the present disclosure. In some examples, the communications manager  815 , 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  820  may transmit signals generated by other components of the device  805 . In some examples, the transmitter  820  may be collocated with a receiver  810  in a transceiver module. For example, the transmitter  820  may be an example of aspects of the transceiver  1120  described with reference to  FIG.  11   . The transmitter  820  may utilize a single antenna or a set of antennas. 
       FIG.  9    shows a block diagram  900  of a device  905  that supports reference signals for CLI measurement in accordance with aspects of the present disclosure. The device  905  may be an example of aspects of a device  805 , or a base station  105  as described herein. The device  905  may include a receiver  910 , a communications manager  915 , and a transmitter  935 . 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 reference signals for CLI measurement, 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  1120  described with reference to  FIG.  11   . The receiver  910  may utilize a single antenna or a set of antennas. 
     The communications manager  915  may be an example of aspects of the communications manager  815  as described herein. The communications manager  915  may include a configuration component  920 , an indication transmission component  925 , and an interference report component  930 . The communications manager  915  may be an example of aspects of the communications manager  1110  described herein. 
     The configuration component  920  may transmit, to a first UE, a CLI measurement configuration which provides a CLI measurement resource for measurement by the first UE of CLI from an aggressor UE. 
     The indication transmission component  925  may transmit, to the first UE, an indication of a reference cell to be used by the first UE for estimation of a CLI measurement resource timing. 
     The interference report component  930  may receive a CLI report from the first UE which includes one or more CLI measurements made by the first UE on the CLI measurement resource and in accordance with the CLI measurement resource timing. 
     The transmitter  935  may transmit signals generated by other components of the device  905 . In some examples, the transmitter  935  may be collocated with a receiver  910  in a transceiver module. For example, the transmitter  935  may be an example of aspects of the transceiver  1120  described with reference to  FIG.  11   . The transmitter  935  may utilize a single antenna or a set of antennas. 
       FIG.  10    shows a block diagram  1000  of a communications manager  1005  that supports reference signals for CLI measurement in accordance with aspects of the present disclosure. The communications manager  1005  may be an example of aspects of a communications manager  815 , a communications manager  915 , or a communications manager  1110  described herein. The communications manager  1005  may include a configuration component  1010 , an indication transmission component  1015 , an interference report component  1020 , and a reference identification component  1025 . Each of these modules may communicate, directly or indirectly, with one another (e.g., via one or more buses). 
     The configuration component  1010  may transmit, to a first UE, a CLI measurement configuration which provides a CLI measurement resource for measurement by the first UE of CLI from an aggressor UE. 
     The indication transmission component  1015  may transmit, to the first UE, an indication of a reference cell to be used by the first UE for estimation of a CLI measurement resource timing. 
     In some examples, the indication transmission component  1015  may indicate, with the CLI measurement configuration, that the reference cell is a serving cell of the aggressor UE. 
     In some cases, the indication includes a SSB index corresponding to the serving cell of the aggressor UE, a CSI-RS index corresponding to the serving cell of the aggressor UE, or both. 
     The interference report component  1020  may receive a CLI report from the first UE which includes one or more CLI measurements made by the first UE on the CLI measurement resource and in accordance with the CLI measurement resource timing. 
     The reference identification component  1025  may indicate, to the first UE, an identifier of a reference serving cell, where the reference serving cell is different from a serving cell of the aggressor UE. 
       FIG.  11    shows a diagram of a system  1100  including a device  1105  that supports reference signals for CLI measurement in accordance with aspects of the present disclosure. The device  1105  may be an example of or include the components of device  805 , device  905 , or a base station  105  as described herein. The device  1105  may include components for bi-directional voice and data communications including components for transmitting and receiving communications, including a communications manager  1110 , a network communications manager  1115 , a transceiver  1120 , an antenna  1125 , memory  1130 , a processor  1140 , and an inter-station communications manager  1145 . These components may be in electronic communication via one or more buses (e.g., bus  1150 ). 
     The communications manager  1110  may transmit, to a first UE, a CLI measurement configuration which provides a CLI measurement resource for measurement by the first UE of CLI from an aggressor UE, transmit, to the first UE, an indication of a reference cell to be used by the first UE for estimation of a CLI measurement resource timing, and receive a CLI report from the first UE which includes one or more CLI measurements made by the first UE on the CLI measurement resource and in accordance with the CLI measurement resource timing. 
     The network communications manager  1115  may manage communications with the core network (e.g., via one or more wired backhaul links). For example, the network communications manager  1115  may manage the transfer of data communications for client devices, such as one or more UEs  115 . 
     The transceiver  1120  may communicate bi-directionally, via one or more antennas, wired, or wireless links as described above. For example, the transceiver  1120  may represent a wireless transceiver and may communicate bi-directionally with another wireless transceiver. The transceiver  1120  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  1125 . However, in some cases the device may have more than one antenna  1125 , which may be capable of concurrently transmitting or receiving multiple wireless transmissions. 
     The memory  1130  may include RAM, ROM, or a combination thereof. The memory  1130  may store computer-readable code  1135  including instructions that, when executed by a processor (e.g., the processor  1140 ) cause the device to perform various functions described herein. In some cases, the memory  1130  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  1140  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  1140  may be configured to operate a memory array using a memory controller. In some cases, a memory controller may be integrated into processor  1140 . The processor  1140  may be configured to execute computer-readable instructions stored in a memory (e.g., the memory  1130 ) to cause the device  1105  to perform various functions (e.g., functions or tasks supporting reference signals for CLI measurement). 
     The inter-station communications manager  1145  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  1145  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  1145  may provide an X2 interface within an LTE/LTE-A wireless communication network technology to provide communication between base stations  105 . 
     The code  1135  may include instructions to implement aspects of the present disclosure, including instructions to support wireless communications. The code  1135  may be stored in a non-transitory computer-readable medium such as system memory or other type of memory. In some cases, the code  1135  may not be directly executable by the processor  1140  but may cause a computer (e.g., when compiled and executed) to perform functions described herein. 
       FIG.  12    shows a flowchart illustrating a method  1200  that supports reference signals for CLI measurement in accordance with aspects of the present disclosure. The operations of method  1200  may be implemented by a UE  115  or its components as described herein. For example, the operations of method  1200  may be performed by a communications manager as described with reference to  FIGS.  4  through  7   . 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  1205 , the UE may receive a CLI measurement configuration which provides a CLI measurement resource for the UE for measurement of CLI from an aggressor UE. The operations of  1205  may be performed according to the methods described herein. In some examples, aspects of the operations of  1205  may be performed by a measurement configuration component as described with reference to  FIGS.  4  through  7   . 
     At  1210 , the UE may select, based on a selection priority, a reference cell for estimation of a CLI measurement resource timing. The operations of  1210  may be performed according to the methods described herein. In some examples, aspects of the operations of  1210  may be performed by a reference cell selection component as described with reference to  FIGS.  4  through  7   . 
     At  1215 , the UE may determine a reference cell timing based on a reference signal of the reference cell. The operations of  1215  may be performed according to the methods described herein. In some examples, aspects of the operations of  1215  may be performed by a reference cell timing component as described with reference to  FIGS.  4  through  7   . 
     At  1220 , the UE may estimate the CLI measurement resource timing based on the reference cell timing. The operations of  1220  may be performed according to the methods described herein. In some examples, aspects of the operations of  1220  may be performed by a resource timing component as described with reference to  FIGS.  4  through  7   . 
     At  1225 , the UE may measure CLI from the aggressor UE in accordance with the CLI measurement resource timing. The operations of  1225  may be performed according to the methods described herein. In some examples, aspects of the operations of  1225  may be performed by an interference measurement component as described with reference to  FIGS.  4  through  7   . 
       FIG.  13    shows a flowchart illustrating a method  1300  that supports reference signals for CLI measurement 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 communications manager as described with reference to  FIGS.  4  through  7   . 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 a CLI measurement configuration which provides a CLI measurement resource for the UE for measurement of CLI from an aggressor UE. 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 measurement configuration component as described with reference to  FIGS.  4  through  7   . 
     At  1310 , the UE may receive, with the CLI measurement configuration, an indication that the reference cell is a serving cell of the aggressor UE. 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 a reference cell indication component as described with reference to  FIGS.  4  through  7   . 
     At  1315 , the UE may select, based on a selection priority, a reference cell for estimation of a CLI measurement resource timing. 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 reference cell selection component as described with reference to  FIGS.  4  through  7   . 
     At  1320 , the UE may select the serving cell of the aggressor UE as the reference cell based on the selection priority. 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 reference cell selection component as described with reference to  FIGS.  4  through  7   . 
     At  1325 , the UE may determine a reference cell timing based on a reference signal of the reference cell. The operations of  1325  may be performed according to the methods described herein. In some examples, aspects of the operations of  1325  may be performed by a reference cell timing component as described with reference to  FIGS.  4  through  7   . 
     At  1330 , the UE may estimate the CLI measurement resource timing based on the reference cell timing. The operations of  1330  may be performed according to the methods described herein. In some examples, aspects of the operations of  1330  may be performed by a resource timing component as described with reference to  FIGS.  4  through  7   . 
     At  1335 , the UE may measure CLI from the aggressor UE in accordance with the CLI measurement resource timing. The operations of  1335  may be performed according to the methods described herein. In some examples, aspects of the operations of  1335  may be performed by an interference measurement component as described with reference to  FIGS.  4  through  7   . 
       FIG.  14    shows a flowchart illustrating a method  1400  that supports reference signals for CLI measurement 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 communications manager as described with reference to  FIGS.  4  through  7   . 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 a CLI measurement configuration which provides a CLI measurement resource for the UE for measurement of CLI from an aggressor UE. 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 measurement configuration component as described with reference to  FIGS.  4  through  7   . 
     At  1410 , the UE may identify a reference serving cell configured for estimation of the CLI measurement resource timing. 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 a reference cell selection component as described with reference to  FIGS.  4  through  7   . 
     At  1415 , the UE may select, based on a selection priority, a reference cell for estimation of a CLI measurement resource timing. 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 reference cell selection component as described with reference to  FIGS.  4  through  7   . 
     At  1420 , the UE may select the reference serving cell as the reference cell based on the selection priority, where the selection priority is that the UE selects the reference serving cell when the CLI measurement configuration does not identify the reference cell as a serving cell of the aggressor UE. 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 reference cell selection component as described with reference to  FIGS.  4  through  7   . 
     At  1425 , the UE may determine a reference cell timing based on a reference signal of the reference cell. 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 reference cell timing component as described with reference to  FIGS.  4  through  7   . 
     At  1430 , the UE may estimate the CLI measurement resource timing based on the reference cell timing. 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 resource timing component as described with reference to  FIGS.  4  through  7   . 
     At  1435 , the UE may measure CLI from the aggressor UE in accordance with the CLI measurement resource timing. The operations of  1435  may be performed according to the methods described herein. In some examples, aspects of the operations of  1435  may be performed by an interference measurement component as described with reference to  FIGS.  4  through  7   . 
       FIG.  15    shows a flowchart illustrating a method  1500  that supports reference signals for CLI measurement in accordance with aspects of the present disclosure. The operations of method  1500  may be implemented by a UE  115  or its components as described herein. For example, the operations of method  1500  may be performed by a communications manager as described with reference to  FIGS.  4  through  7   . 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  1505 , the UE may receive a CLI measurement configuration which provides a CLI measurement resource for the UE for measurement of CLI from an aggressor UE. 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 measurement configuration component as described with reference to  FIGS.  4  through  7   . 
     At  1510 , the UE may select, based on a selection priority, a reference cell for estimation of a CLI measurement resource timing. 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 a reference cell selection component as described with reference to  FIGS.  4  through  7   . 
     At  1515 , the UE may select a serving cell of the UE as the reference cell based on the selection priority, where the selection priority is that the UE selects the serving cell of the UE when the CLI measurement configuration does not identify the reference cell as a serving cell of the aggressor UE, and when no reference serving cell has been configured. 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 reference cell selection component as described with reference to  FIGS.  4  through  7   . 
     At  1520 , the UE may determine a reference cell timing based on a reference signal of the reference cell. The operations of  1520  may be performed according to the methods described herein. In some examples, aspects of the operations of  1520  may be performed by a reference cell timing component as described with reference to  FIGS.  4  through  7   . 
     At  1525 , the UE may estimate the CLI measurement resource timing based on the reference cell timing. The operations of  1525  may be performed according to the methods described herein. In some examples, aspects of the operations of  1525  may be performed by a resource timing component as described with reference to  FIGS.  4  through  7   . 
     At  1530 , the UE may measure CLI from the aggressor UE in accordance with the CLI measurement resource timing. The operations of  1530  may be performed according to the methods described herein. In some examples, aspects of the operations of  1530  may be performed by an interference measurement component as described with reference to  FIGS.  4  through  7   . 
       FIG.  16    shows a flowchart illustrating a method  1600  that supports reference signals for CLI measurement 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 communications manager as described with reference to  FIGS.  8  through  11   . 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 first UE, a CLI measurement configuration which provides a CLI measurement resource for measurement by the first UE of CLI from an aggressor UE. 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 component as described with reference to  FIGS.  8  through  11   . 
     At  1610 , the base station may transmit, to the first UE, an indication of a reference cell to be used by the first UE for estimation of a CLI measurement resource timing. 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 indication transmission component as described with reference to  FIGS.  8  through  11   . 
     At  1615 , the base station may receive a CLI report from the first UE which includes one or more CLI measurements made by the first UE on the CLI measurement resource and in accordance with the CLI measurement resource timing. 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 an interference report component as described with reference to  FIGS.  8  through  11   . 
     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. 
     Example 1: A method of wireless communication, comprising: receiving a CLI measurement configuration which provides a CLI measurement resource for the UE for measurement of CLI from an aggressor UE; selecting, based on a selection priority, a reference cell for estimation of a CLI measurement resource timing; determining a reference cell timing based on a reference signal of the reference cell; estimating the CLI measurement resource timing based on the reference cell timing; and measuring CLI from the aggressor UE in accordance with the CLI measurement resource timing. 
     Example 2: The method of example 1, further comprising: receiving, with the CLI measurement configuration, an indication that the reference cell may be a serving cell of the aggressor UE; and selecting the serving cell of the aggressor UE as the reference cell based on the selection priority. 
     Example 3: The method of any of examples 1 or 2, wherein the indication includes a SSB index corresponding to the serving cell of the aggressor UE, a CSI-RS index corresponding to the serving cell of the aggressor UE, or both. 
     Example 4: The method of any of examples 1-3, further comprising: using the SSB index or the CSI-RS index as the reference signal from which the reference cell timing may be determined. 
     Example 5: The method of any of examples 1-4, further comprising: identifying a frequency offset of the CLI measurement resource, based at least in part on measurements of the reference signal. 
     Example 6: The method of any of examples 1-5, further comprising: applying a frequency correction corresponding to the identified frequency offset in the CLI measurement resource. 
     Example 7: The method of any of examples 1 and 5-6, further comprising: identifying a reference serving cell configured for estimation of the CLI measurement resource timing; and selecting the reference serving cell as the reference cell based on the selection priority, where the selection priority may be that the UE selects the reference serving cell when the CLI measurement configuration does not identify the reference cell as a serving cell of the aggressor UE. 
     Example 8: The method of any of examples 1 and 5-7, further comprising: using a SSB or a CSI-RS of the reference serving cell to determine the reference cell timing. 
     Example 9: The method of any of examples 1 and 5-6, further comprising: selecting a serving cell of the UE as the reference cell based on the selection priority, where the selection priority may be that the UE selects the serving cell of the UE when the CLI measurement configuration does not identify the reference cell as a serving cell of the aggressor UE, and when no reference serving cell may have been configured. 
     Example 10: An apparatus comprising at least one means for performing a method of any of examples 1-9. 
     Example 11: An apparatus for wireless communications comprising a processor; memory coupled with the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform a method of any of examples 1-9. 
     Example 12: A non-transitory computer-readable medium storing code for wireless communications, the code comprising instructions executable by a processor to perform a method od any of examples 1-9. 
     Example 13: A method of wireless communication, comprising: transmitting, to a first UE, a CLI measurement configuration which provides a CLI measurement resource for measurement by the first UE of CLI from an aggressor UE; transmitting, to the first UE, an indication of a reference cell to be used by the first UE for estimation of a CLI measurement resource timing; and receiving a CLI report from the first UE which includes one or more CLI measurements made by the first UE on the CLI measurement resource and in accordance with the CLI measurement resource timing. 
     Example 14: The method of example 13, further comprising: indicating, with the CLI measurement configuration, that the reference cell is a serving cell of the aggressor UE. 
     Example 15: The method of any of examples 13 and 14, wherein: the indication comprises a SSB index corresponding to the serving cell of the aggressor UE, a CSI-RS index corresponding to the serving cell of the aggressor UE, or both. 
     Example 16: The method of any of examples 13-15, further comprising: indicating, to the first UE, an identifier of a reference serving cell, wherein the reference serving cell is different from a serving cell of the aggressor UE. 
     Example 17: An apparatus comprising at least one means for performing a method of any of examples 13-15. 
     Example 18: An apparatus for wireless communications comprising a processor; memory coupled with the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform a method of any of examples 13-15. 
     Example 19: A non-transitory computer-readable medium storing code for wireless communications, the code comprising instructions executable by a processor to perform a method of any of examples 13-15. 
     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.