Patent Description:
Aspects of the present disclosure generally relate to wireless communication and to techniques and apparatuses for deriving channel state information (CSI) using a subset of configured CSI reference signal (CSI-RS) resources.

Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc.).

Relatedly, document <CIT> describes a method and apparatus of reporting CSI in a wireless communication system, document 3GPP RP-<NUM> describes multi-antenna enhancements for NR and document 3GPP R1-<NUM> describes UE processing relaxation.

In some aspects, a method of wireless communication performed by a user equipment (UE) is provided as defined in claim <NUM>.

In some aspects, a user equipment (UE) for wireless communication is provided as defined in claim <NUM>.

In some aspects, a non-transitory computer-readable medium is provided as defined in claim <NUM>.

Aspects generally include a method, apparatus, system, computer program product, non-transitory computer-readable medium, user equipment, base station, wireless communication device, and/or processing system as substantially described with reference to and as illustrated by the drawings and specification.

Such constructions do not depart from the scope of the appended claims.

To provide a channel state information (CSI) report that is not outdated, a user equipment (UE) may extrapolate (e.g., estimate, derive, and/or the like) future channel conditions using a set of CSI reference signals (CSI-RSs) that occur prior to a CSI reference resource. This may be referred to as extrapolation-based CSI reporting, an extrapolated CSI report, and/or the like. This may permit a base station to select better transmission parameters for a data transmission as compared to using outdated CSI. However, in some cases, the UE may not be able to measure all configured CSI-RSs and/or may not be able to use all of the configured CSI-RSs to derive CSI parameters. In these cases, rather than transmit the CSI report, the UE may be configured to drop the CSI report. However, if the UE is able to measure a subset of the configured CSI-RSs, then dropping the CSI report may lead to sub-optimal selection of transmission parameters by the base station as compared to extrapolating CSI parameters using a subset of the configured CSI-RSs. Some techniques and apparatuses described herein improve selection of transmission parameter by the base station by permitting the UE to extrapolate or derive CSI parameters for a CSI report using a subset of configured CSI-RSs in a CSI reference resource interval.

These apparatuses and techniques will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as "elements").

A relay BS may also be referred to as a relay station, a relay base station, a relay, etc..

Wireless network <NUM> may be a heterogeneous network that includes BSs of different types, e.g., macro BSs, pico BSs, femto BSs, relay BSs, etc. These different types of BSs may have different transmit power levels, different coverage areas, and different impacts on interference in wireless network <NUM>.

A UE may also be referred to as an access terminal, a terminal, a mobile station, a subscriber unit, a station, etc. A UE may be a cellular phone (e.g., a smart phone), a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet, a camera, a gaming device, a netbook, a smartbook, an ultrabook, a medical device or equipment, biometric sensors/devices, wearable devices (smart watches, smart clothing, smart glasses, smart wrist bands, smart jewelry (e.g., smart ring, smart bracelet)), an entertainment device (e.g., a music or video device, or a satellite radio), a vehicular component or sensor, smart meters/sensors, industrial manufacturing equipment, a global positioning system device, or any other suitable device that is configured to communicate via a wireless or wired medium.

MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, location tags, etc., that may communicate with a base station, another device (e.g., remote device), or some other entity. Some UEs may be considered Internet-of Things (IoT) devices, and/or may be implemented as may be implemented as NB-IoT (narrowband internet of things) devices.

Transmit processor <NUM> may also process system information (e.g., for semi-static resource partitioning information (SRPI), etc.) and control information (e.g., CQI requests, grants, upper layer signaling, etc.) and provide overhead symbols and control symbols.

A channel processor may determine reference signal received power (RSRP), received signal strength indicator (RSSI), reference signal received quality (RSRQ), channel quality indicator (CQI), etc. In some aspects, one or more components of UE <NUM> may be included in a housing.

On the uplink, at UE <NUM>, a transmit processor <NUM> may receive and process data from a data source <NUM> and control information (e.g., for reports comprising RSRP, RSSI, RSRQ, CQI, etc.) from controller/processor <NUM>. The symbols from transmit processor <NUM> may be precoded by a TX MIMO processor <NUM> if applicable, further processed by modulators 254a through 254r (e.g., for DFT-s-OFDM, CP-OFDM, etc.), and transmitted to base station <NUM>.

Controller/processor <NUM> of base station <NUM>, controller/processor <NUM> of UE <NUM>, and/or any other component(s) of <FIG> may perform one or more techniques associated with deriving channel state information (CSI) using a subset of configured CSI reference signal (CSI-RS) resources, as described in more detail elsewhere herein. For example, controller/processor <NUM> of base station <NUM>, controller/processor <NUM> of UE <NUM>, and/or any other component(s) of <FIG> may perform or direct operations of, for example, process <NUM> of <FIG> and/or other processes as described herein. Memories <NUM> and <NUM> may store data and program codes for base station <NUM> and UE <NUM>, respectively.

The stored program codes, when executed by processor <NUM> and/or other processors and modules at UE <NUM>, may cause the UE <NUM> to perform operations described with respect to process <NUM> of <FIG> and/or other processes as described herein.

In some aspects, UE <NUM> may include means for receiving a configuration that indicates a set of channel state information reference signals (CSI-RSs) to be measured by the UE for deriving channel state information (CSI), one or more time domain resources (e.g., one or more slots) for which the UE is to derive the CSI, and a time domain resource (e.g., a slot) for transmission of a CSI report that includes the CSI, wherein the one or more time domain resources (e.g., the one or more slots) for which the UE is to derive the CSI occur after the time domain resource (e.g., the slot) for transmission of the CSI report; means for determining that the UE cannot measure a first subset of CSI-RSs included in the set of CSI-RSs; means for deriving one or more parameters for the CSI report based at least in part on measuring a second subset of CSI-RSs included in the set of CSI-RSs, wherein the second subset of CSI-RSs excludes the first subset of CSI-RSs; means for transmitting the CSI report, including the one or more parameters, in the time domain resource (e.g., the slot) for transmission of the CSI report; and/or the like. In some aspects, such means may include one or more components of UE <NUM> described in connection with <FIG>.

For example, the functions described with respect to the transmit processor <NUM>, the receive processor <NUM>, and/or the TX MIMO processor <NUM> may be performed by or under the control of processor <NUM>.

<FIG> is a diagram illustrating an example <NUM> of CSI reporting, in accordance with various aspects of the present disclosure.

As shown by reference number <NUM>, a UE may measure one or more CSI-RSs transmitted by a base station at a first time n<NUM> (e.g., in a first slot or time domain resource), the UE may transmit a CSI report to the base station based at least in part on those measurements at a second time n<NUM> (e.g., in a second slot or time domain resource) after processing the one or more CSI-RSs, and the base station may transmit data to the UE based at least in part on the CSI report at a third time n<NUM> (e.g., in a third slot or time domain resource). The CSI-RS measurements at time n<NUM> may indicate channel conditions at time n<NUM>. However, the channel conditions at time n<NUM>, when the base station transmits data based at least in part on the CSI report of the CSI-RS measurements, may be different from the channel conditions at time n<NUM>. This may be referred to as channel aging. As a result, the base station may select sub-optimal transmission parameters for transmission of the data at time n<NUM>. Such transmission parameters may include, for example, a modulation and coding scheme (MCS), a rank, a precoder, a beam, a multiple input multiple output (MIMO) layer, and/or the like. This may result in a missed communication if channel conditions have degraded between time n<NUM> and time n<NUM>, or may result in under-utilization of network resources if channel conditions have improved between time n<NUM> and time n<NUM>.

As shown by reference number <NUM>, a UE may transmit a CSI report in a CSI reporting slot n'. The CSI report may be based at least in part on a CSI reference resource that occurs in a slot prior to transmission of the CSI report. In the time domain, the CSI reference resource for CSI reporting in uplink slot n' may be defined by a downlink slot n - nCSI_ref, as shown, where n depends on n' and the subcarrier spacing configurations for downlink and uplink, and where nCSI_ref is a valid downlink slot that depends on various factors such as whether CSI reporting is periodic, aperiodic, or semi-persistent. The UE uses one or more CSI-RSs that are received no later than the CSI reference resource (e.g., that are received in or before the CSI reference resource) to derive parameters for the CSI report. Thus, the CSI report represents channel conditions in or prior to the CSI reference resource. However, due to channel aging described above, the CSI report is outdated, and a subsequent data transmission by a base station that occurs after the CSI report is configured according to outdated channel conditions, as described above.

To provide a CSI report that is not outdated, a UE may extrapolate (e.g., estimate, derive, and/or the like) future channel conditions using a set of CSI-RSs that occur prior to the CSI reference resource, as described in more detail below in connection with <FIG>. This may be referred to as extrapolation-based CSI reporting, an extrapolated CSI report, and/or the like. In this way, the base station may select better transmission parameters for a data transmission as compared to using outdated CSI.

<FIG> is a diagram illustrating an example <NUM> of extrapolation-based CSI reporting, in accordance with various aspects of the present disclosure. As shown in <FIG>, a UE <NUM> and a base station <NUM> may communicate with one another.

As shown by reference number <NUM>, the base station <NUM> may transmit, to the UE <NUM>, a configuration for CSI reporting. The configuration may be for an extrapolated CSI report, where the UE <NUM> uses a set of CSI-RSs to derive CSI parameters for one or more slots that occur later in time than the set of CSI-RSs and/or that occur later in time than the slot used to transmit the CSI report. In some aspects, the configuration may be indicated in a radio resource control (RRC) message, such as an RRC configuration message, an RRC reconfiguration message, and/or the like. Although some aspects are described herein as being performed in connection with CSI-RS, these aspects may also apply to CSI for interference management (CSI-IM).

As shown by reference number <NUM>, the configuration may indicate a set of CSI-RSs to be measured by the UE <NUM> to derive CSI. As shown, the set of CSI-RSs may occur in a set of CSI-RS resources within a CSI reference resource interval. The CSI reference resource interval may include multiple transmission time intervals (TTIs) (e.g., slots or other time domain resources). For example, the CSI reference resource interval may span a number of slots starting with a slot shown as n - nCSI_ref - nCSI_span and ending with a slot shown as n - nCSI_ref. The slot n - nCSI_ref is described above in connection with <FIG>, and the slot n - nCSI_ref - nCSI_span may occur nCSI_span slots before the slot n - nCSI_ref, where nCSI_span represents the length of the CSI reference resource interval. In example <NUM>, the CSI reference resource interval is five slots in length.

In some aspects, the set of CSI-RSs to be measured by the UE <NUM> spans across multiple non-adjacent symbols associated with a single CSI-RS transmission occasion. For example, the UE <NUM> may be configured with a single CSI-RS resource that includes multiple symbols (e.g., non-adjacent symbols). The non-adjacent symbols may occur in the CSI reference resource interval, as shown. Alternatively, the set of CSI-RSs to be measured by the UE <NUM> includes multiple one-symbol CSI-RS transmission occasions that occur in non-adjacent symbols. For example, the UE <NUM> may be configured with multiple CSI-RS resources (e.g., multiple CSI-RS transmission occasions) that each occur within a single symbol. The symbols may be non-adjacent and may occur in the CSI reference resource interval, as shown. In example <NUM>, the UE <NUM> may be configured with a single CSI-RS that includes five non-adjacent symbols, or may be configured with five CSI-RS resources that occur in non-adjacent symbols.

As shown by reference number <NUM>, the configuration may indicate one or more slots for which the UE <NUM> is to derive the CSI, shown as CSI reference report slots. As shown, these slots occur after the CSI reference resource interval (e.g., after the set of CSI-RSs to be measured by the UE <NUM>) and after the slot in which the CSI report is transmitted. In example <NUM>, there are four CSI reference report slots, and the UE <NUM> uses the CSI-RSs measured in the CSI reference resource interval to extrapolate and/or derive CSI parameters for the four CSI reference report slots.

As shown by reference number <NUM>, the configuration may indicate a slot for transmission of a CSI report that includes the CSI. In example <NUM>, this slot is shown as slot n', and is described above in connection with <FIG>. In some aspects, the UE <NUM> may be configured with and/or may determine an offset (e.g., a slot offset, a symbol offset, and/or the like) between the CSI reference resource interval and a CSI reference report. For example, the offset may represent an offset between the latest-occurring CSI-RS (e.g., within the CSI reference resource interval) and the earliest-occurring CSI reference report slot for which CSI parameters are to be derived using the set of CSI-RSs.

To provide a CSI report that is not outdated, the UE <NUM> may extrapolate (e.g., estimate, derive, and/or the like) future channel conditions using a set of CSI-RSs that occur in the CSI reference resource interval. For example, the UE <NUM> may use the set of CSI-RSs in the CSI reference resource interval to extrapolate CSI parameters for the CSI reference report slots (e.g., by measuring a change in channel conditions over time). The UE <NUM> may report the extrapolated CSI parameters in the CSI report. Example CSI parameters include a channel quality indicator (CQI) parameter, a precoding matrix indicator (PMI) parameter, a CSI-RS resource indicator (CRI) parameter, a strongest layer indication (SLI) parameter, a rank indication (RI) parameter, a layer <NUM> (L1) reference signal received power (RSRP) (L1-RSRP) parameter, a layer <NUM> (L1) signal-to-interference-plus-noise ratio (SINR) (L1-SINR) parameter, and/or the like. In this way, the base station <NUM> may select better transmission parameters for a data transmission as compared to using outdated CSI.

However, in some cases, the UE <NUM> may not be able to measure all of the configured CSI-RSs and/or may not be able to use all of the configured CSI-RSs to derive CSI parameters for the CSI reference report slots. For example, a CSI-RS may occur too late in time as compared to a corresponding CSI reference report slot (e.g., may occur with too small an offset) to permit the UE <NUM> to process the CSI-RS. As other examples, the UE <NUM> may not be able to measure all of the configured CSI-RSs due to being in a discontinuous reception (DRX) sleep state during the CSI reference resource interval, performing a bandwidth part (BWP) switch during the CSI reference resource interval, undergoing serving cell activation during the CSI reference resource interval, receiving a reconfiguration of a CSI report, receiving an indication to activate CSI reporting (e.g., semi-persistent CSI reporting and/or the like), reconfiguration of a CSI-RS slot to an uplink slot, and/or the like.

In these cases, rather than transmit the CSI report, the UE <NUM> may be configured to drop the CSI report (e.g., by refraining from transmitting the CSI report). However, if the UE <NUM> is able to measure a subset of the configured CSI-RSs, then dropping the CSI report may lead to sub-optimal selection of transmission parameters by the base station <NUM> as compared to extrapolating CSI parameters using a subset of the configured CSI-RSs. Some techniques and apparatuses described herein improve selection of transmission parameters by the base station <NUM> by permitting the UE <NUM> to extrapolate or derive CSI parameters for a CSI report using a subset of configured CSI-RSs in a CSI reference resource interval.

<FIG> is a diagram illustrating an example <NUM> of deriving CSI using a subset of configured CSI-RS resources, in accordance with various aspects of the present disclosure. As shown in <FIG>, a UE <NUM> and a base station <NUM> may communicate with one another.

As shown by reference number <NUM>, the base station <NUM> may transmit, to the UE <NUM>, a configuration for CSI reporting, as described above in connection with <FIG>. The configuration may be for an extrapolated CSI report, where the UE <NUM> uses a set of CSI-RSs to derive CSI parameters for one or more slots that occur later in time than the set of CSI-RSs and/or that occur later in time than the slot used to transmit the CSI report. In some aspects, the configuration may be indicated in an RRC message, such as an RRC configuration message, an RRC reconfiguration message, and/or the like. As described above in connection with <FIG>, the configuration may indicate a set of CSI-RSs to be measured by the UE <NUM> (e.g., in a CSI reference resource interval) for deriving CSI, one or more slots (e.g., one or more CSI reference report slots) for which the UE <NUM> is to derive the CSI, and a slot for transmission of a CSI report that includes the CSI. As described above in connection with <FIG>, the one or more slots for which the UE <NUM> is to derive the CSI may occur after the slot for transmission of the CSI report. Although some techniques are described herein in connection with slots, these techniques may be applied for other time domain resources, such as subframes, mini-slots, symbols, sets of symbols, and/or the like, which may be consecutive or non-consecutive.

As shown by reference number <NUM>, the UE <NUM> may determine that the UE <NUM> cannot measure a first subset of CSI-RSs (e.g., one or more CSI-RSs) included in the configured set of CSI-RSs. For example, the UE <NUM> may be unable to measure the first subset of CSI-RSs due to a timing of the first subset of CSI-RSs relative to the slot for transmission of the CSI report. For example, the UE <NUM> may be unable to measure the first subset of CSI-RSs because the first subset of CSI-RSs occurs too late in time to be included in the CSI report. For example, the UE <NUM> may not be expected to measure a CSI-RS if the last symbol (e.g., OFDM symbol) of the CSI-RS is received less than a threshold number of symbols (shown as Z' symbols) before a transmission time of the first symbol (e.g., the first OFDM symbol) of the CSI report. As shown by reference number <NUM>, one of the configured CSI-RSs occurs too late in time compared to the CSI report, and thus the UE <NUM> cannot use this CSI-RS to determine a CSI parameter to be included in the CSI report (e.g., due to insufficient processing time).

Additionally, or alternatively, as shown by reference number <NUM>, the UE <NUM> may be unable to measure the first subset of CSI-RSs because a set of symbols in which the first subset of CSI-RSs occurs are reconfigured to uplink symbols and/or are otherwise modified such that the CSI-RSs do not occur in the set of symbols or transmission of the CSI-RSs in the set of symbols would result in a collision with another communication. For example, a CSI-RS symbol may be reconfigured to an uplink symbol (e.g., causing an uplink collision), may be reconfigured to carry transmissions for another physical (PHY) channel, may be punctured, and/or the like.

Additionally, or alternatively, the UE <NUM> may not be able to measure the first subset of CSI-RSs because the UE <NUM> is undergoing a BWP switch when the first subset of CSI-RSs occurs, as described in more detail below in connection with <FIG>. Additionally, or alternatively, the UE <NUM> may not be able to measure the first subset of CSI-RSs because the UE <NUM> is in a DRX sleep state when the first subset of CSI-RSs occurs, as described in more detail below in connection with <FIG>. Additionally, or alternatively, the UE <NUM> may not be able to measure the first subset of CSI-RSs because the UE <NUM> is undergoing serving cell activation when the first subset of CSI-RSs occurs, because the UE <NUM> has received a configuration or a reconfiguration of a CSI report after the first subset of CSI-RSs occurs, because the UE <NUM> has received an indication to activate CSI reporting (e.g., semi-persistent CSI reporting and/or the like) after the first subset of CSI-RSs occur, and/or the like.

As shown by reference number <NUM>, the UE <NUM> may derive one or more parameters for the CSI report (e.g., one or more CSI parameters) based at least in part on measuring a second subset of CSI-RSs included in the set of CSI-RSs. The second subset of CSI-RSs measured by the UE <NUM> excludes the first subset of CSI-RSs that cannot be measured by the UE <NUM>. In example <NUM>, the UE <NUM> uses the first four out of five configured CSI-RSs to derive the one or more CSI parameters, and excludes the fifth (e.g., latest-occurring) configured CSI-RS from being used for the derivation.

In some aspects, the UE <NUM> may derive the one or more parameters for the CSI report based at least in part on a determination that the second subset of CSI-RSs (e.g., capable of being measured by the UE <NUM> for the extrapolated CSI report) includes a threshold number of CSI-RSs. In some aspects, the threshold number may be two or may be at least two because the UE <NUM> may need to measure at least two CSI-RSs to extrapolate a change in channel conditions over time. Additionally, or alternatively, the threshold number may be based at least in part on a UE capability. For example, different UEs <NUM> may have different capabilities for extrapolating CSI parameters from CSI-RSs, with some UEs <NUM> requiring fewer CSI-RSs to perform extrapolation and some UEs <NUM> requiring more CSI-RSs to perform extrapolation. In some aspects, the threshold number may be configured for the UE <NUM> by the base station <NUM> (e.g., in an RRC message). For example, the base station <NUM> may require a certain degree of accuracy for CSI parameter extrapolation, and the degree of accuracy may depend on the number of CSI-RSs used to perform the extrapolation.

As described above in connection with <FIG>, in some aspects, the configured set of CSI-RSs may span across multiple non-adjacent symbols associated with a single CSI-RS transmission occasion. In this case, the threshold number may represent a threshold number of non-adjacent symbols (e.g., at least two non-adjacent symbols that each carry a CSI-RS). Thus, the threshold number may represent a minimum number of OFDM symbols (e.g., non-adjacent or non-consecutive OFDM symbols) that include CSI-RSs. Furthermore, in this case, the UE <NUM> may determine that the threshold number is satisfied if the second set of CSI-RSs includes CSI-RSs in the threshold number of non-adjacent symbols.

Alternatively, as also described above in connection with <FIG>, the configured set of CSI-RSs may include multiple one-symbol CSI-RS transmission occasions that occur in non-adjacent symbols. In this case, the threshold number may represent a threshold number of one-symbol CSI-RS transmission occasions (e.g., at least two one-symbol CSI-RS transmission occasions). Thus, the threshold number may represent a minimum number of CSI-RS resources. Furthermore, in this case, the UE <NUM> may determine that the threshold number is satisfied if the second set of CSI-RSs includes CSI-RSs in the threshold number of one-symbol CSI-RS transmission occasions.

As shown by reference number <NUM>, the UE <NUM> may transmit the CSI report, including the one or more CSI parameters, in the slot for transmission of the CSI report. In some aspects, the UE <NUM> may transmit the CSI report based at least in part on a determination that the second subset of CSI-RSs include a threshold number of CSI-RSs, in a similar manner as described above. In this case, if the second subset of CSI-RSs includes the threshold number of CSI-RSs, then the UE <NUM> may transmit the CSI report. Conversely, if the second subset of CSI-RSs does not include the threshold number of CSI-RSs, then the UE <NUM> may drop the CSI report (e.g., may refrain from transmitting the CSI report). Alternatively, if the second subset of CSI-RSs does not include the threshold number of CSI-RSs, then the UE <NUM> may refrain from updating the CSI report (e.g., may transmit a dummy CSI report or a default CSI report, may retransmit a most recently transmitted CSI report, may transmit CSI parameters from the most recently transmitted CSI report, and/or the like).

By using a subset of the configured CSI-RSs to extrapolate CSI parameters for a CSI report rather than dropping the CSI report, the UE <NUM> may be able to improve selection of transmission parameters by the base station <NUM>.

<FIG> is a diagram illustrating an example <NUM> of deriving CSI using a subset of configured CSI-RS resources, in accordance with various aspects of the present disclosure.

As shown by reference number <NUM>, a UE <NUM> may determine that the UE <NUM> cannot measure a first subset of CSI-RSs included in a configured set of CSI-RSs, as described above in connection with <FIG>. In example <NUM>, the UE <NUM> is undergoing BWP switching (e.g., a BWP change) during the CSI reference resource interval (e.g., during a portion of the CSI reference resource interval). As a result, the UE <NUM> cannot measure the first two CSI-RSs of a set of five CSI-RSs configured for a BWP to which the UE <NUM> switches.

In example <NUM>, the UE <NUM> determines that the UE <NUM> cannot measure the first subset of CSI-RSs based at least in part on detecting the change in BWP. However, in some aspects, the UE <NUM> may determine that the UE <NUM> cannot measure the first subset of CSI-RSs based at least in part on detecting a CSI report configuration, a CSI report reconfiguration, a serving cell activation, an activation of CSI (e.g., semi-persistent CSI), and/or the like.

As shown by reference number <NUM>, the UE <NUM> may derive one or more CSI parameters for the CSI report based at least in part on measuring a second subset of CSI-RSs included in the configured set of CSI-RSs, in a similar manner as described above in connection with <FIG>. In example <NUM>, the UE <NUM> completes the BWP switch and measures the last three CSI-RSs of the set of five CSI-RSs configured for the BWP to which the UE <NUM> switches.

As shown by reference number <NUM>, the UE <NUM> may transmit the CSI report, including the one or more derived CSI parameters, in a slot for transmission of the CSI report, in a similar manner as described above in connection with <FIG>. In some aspects, the UE <NUM> may transmit the CSI report based at least in part on a determination that the second subset of CSI-RSs include a threshold number of CSI-RSs (e.g., at least two CSI-RSs, at least three CSI-RSs, or the like), in a similar manner as described above. Additionally, or alternatively, the UE <NUM> may transmit the CSI report based at least in part on a determination that the second subset of CSI-RSs includes a threshold number of CSI-RSs that are received within a CSI reference resource interval associated with the CSI report (e.g., at least Z' symbols before transmission of the CSI report). In this way, the UE <NUM> may be able to improve selection of transmission parameters by the base station <NUM>.

As shown by reference number <NUM>, a UE <NUM> may determine that the UE <NUM> cannot measure a first subset of CSI-RSs included in a configured set of CSI-RSs, as described above in connection with <FIG>. In example <NUM>, the UE <NUM> is in a DRX sleep state during the CSI reference resource interval (e.g., during a portion of the CSI reference resource interval). As a result, the UE <NUM> cannot measure the first two CSI-RSs of a set of five CSI-RSs configured for the UE <NUM>.

As shown by reference number <NUM>, the UE <NUM> may derive one or more CSI parameters for the CSI report based at least in part on measuring a second subset of CSI-RSs included in the configured set of CSI-RSs, in a similar manner as described above in connection with <FIG>. In example <NUM>, the UE <NUM> exits the DRX sleep state, enters a DRX active state, and measures the last three CSI-RSs of the set of five CSI-RSs during the DRX active state.

As shown by reference number <NUM>, the UE <NUM> may transmit the CSI report, including the one or more derived CSI parameters, in a slot for transmission of the CSI report, in a similar manner as described above in connection with <FIG>. In some aspects, the UE <NUM> may transmit the CSI report based at least in part on a determination that the second subset of CSI-RSs include a threshold number of CSI-RSs (e.g., at least two CSI-RSs, at least three CSI-RSs, or the like), in a similar manner as described above. Additionally, or alternatively, the UE <NUM> may transmit the CSI report based at least in part on a determination that the second subset of CSI-RSs includes a threshold number of CSI-RSs that are received during a DRX active time within a CSI reference resource interval associated with the CSI report (e.g., at least Z' symbols before transmission of the CSI report). In this way, the UE <NUM> may be able to improve selection of transmission parameters by the base station <NUM>.

Additionally, or alternatively, the UE <NUM> may transmit the CSI report based at least in part on a determination that the second subset of CSI-RSs includes a threshold number of latest-occurring CSI-RSs (e.g., of the configured set of CSI-RSs) that occur during a DRX active time. For example, if the UE <NUM> is in the DRX active state for a set of earlier-occurring CSI-RSs of the configured set of CSI-RSs and then enters the DRX sleep state for a set of later-occurring CSI-RSs of the configured set of CSI-RSs, then the UE <NUM> may refrain from transmitting the CSI report. In this case, the UE <NUM> may be in the DRX sleep state during scheduled transmission of the CSI report and/or may not have the latest channel information (as indicated by the later-occurring CSI-RSs), and so may drop the CSI report. In this case, the UE <NUM> may refrain from measuring the earlier-occurring CSI-RSs to conserve UE resources (e.g., processing resources, memory resources, battery power, and/or the like).

<FIG> is a diagram illustrating an example process <NUM> performed, for example, by a UE, in accordance with various aspects of the present disclosure. Example process <NUM> is an example where the UE (e.g., UE <NUM> and/or the like) performs operations associated with deriving CSI using a subset of configured CSI-RS resources.

As shown in <FIG>, in some aspects, process <NUM> may include receiving a configuration that indicates a set of CSI-RSs to be measured by the UE for deriving CSI, one or more time domain resources for which the UE is to derive the CSI, and a time domain resource for transmission of a CSI report that includes the CSI, wherein the one or more time domain resources for which the UE is to derive the CSI occur after the time domain resource for transmission of the CSI report (block <NUM>). For example, the UE (e.g., using receive processor <NUM>, controller/processor <NUM>, memory <NUM>, and/or the like) may receive a configuration that indicates a set of CSI-RSs to be measured by the UE for deriving CSI, one or more time domain resources for which the UE is to derive the CSI, and a time domain resource for transmission of a CSI report that includes the CSI, as described above. In some aspects, the one or more time domain resources for which the UE is to derive the CSI occur after the time domain resource for transmission of the CSI report. In some aspects, the one or more time domain resources are one or more slots, one or more mini-slots, one or more symbols, one or more sets of symbols, one or more subframes, or the like. Similarly, the time domain resource for transmission of the CSI report may be a slot, a mini-slot, a symbol, a set of symbols, a subframe, or the like.

As further shown in <FIG>, in some aspects, process <NUM> may include determining that the UE cannot measure a first subset of CSI-RSs included in the set of CSI-RSs (block <NUM>). For example, the UE (e.g., using receive processor <NUM>, transmit processor <NUM>, controller/processor <NUM>, memory <NUM>, and/or the like) may determine that the UE cannot measure a first subset of CSI-RSs included in the set of CSI-RSs, as described above.

As further shown in <FIG>, in some aspects, process <NUM> may include deriving one or more parameters for the CSI report based at least in part on measuring a second subset of CSI-RSs included in the set of CSI-RSs, wherein the second subset of CSI-RSs excludes the first subset of CSI-RSs (block <NUM>). For example, the UE (e.g., using receive processor <NUM>, transmit processor <NUM>, controller/processor <NUM>, memory <NUM>, and/or the like) may derive one or more parameters for the CSI report based at least in part on measuring a second subset of CSI-RSs included in the set of CSI-RSs, as described above. In some aspects, the second subset of CSI-RSs excludes the first subset of CSI-RSs.

As further shown in <FIG>, in some aspects, process <NUM> may include transmitting the CSI report, including the one or more parameters, in the time domain resource for transmission of the CSI report (block <NUM>). For example, the UE (e.g., using transmit processor <NUM>, controller/processor <NUM>, memory <NUM>, and/or the like) may transmit the CSI report, including the one or more parameters, in the time domain resource for transmission of the CSI report, as described above.

As an example, "at least one of a, b, or c" is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination with multiples of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c).

Claim 1:
A method of wireless communication performed by a user equipment, UE (<NUM>), comprising:
receiving (<NUM>) a configuration that indicates a set of channel state information reference signals, CSI-RSs, to be measured by the UE (<NUM>) for deriving channel state information, CSI, one or more time domain resources for which the UE is to derive the CSI, and a time domain resource for transmission of a CSI report that includes the CSI, wherein the one or more time domain resources for which the UE is to derive the CSI occur after the time domain resource for transmission of the CSI report;
determining (<NUM>) that the UE (<NUM>) cannot measure a first subset of CSI-RSs included in the set of CSI-RSs based at least in part on at least one of:
a collision between at least one CSI-RS, of the first subset of CSI-RSs, and another communication,
a configuration of a symbol of at least one CSI-RS, of the first subset of CSI-RSs, as an uplink symbol, or
puncturing of at least one CSI-RS of the first subset of CSI-RSs;
deriving (<NUM>) one or more parameters for the CSI report based at least in part on measuring a second subset of CSI-RSs included in the set of CSI-RSs, wherein the second subset of CSI-RSs excludes the first subset of CSI-RSs; and
transmitting (<NUM>) the CSI report, including the one or more parameters, in the time domain resource for transmission of the CSI report.