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

A user equipment (UE) may communicate with a base station (BS) via the downlink (DL) and uplink (UL). The DL (or forward link) refers to the communication link from the BS to the UE, and the UL (or reverse link) refers to the communication link from the UE to the BS. As will be described in more detail herein, a BS may be referred to as a NodeB, an LTE evolved nodeB (eNB), a gNB, an access point (AP), a radio head, a transmit receive point (TRP), a New Radio (NR) BS, a <NUM> NodeB, or further examples.

The above multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different UEs to communicate on a municipal, national, regional, and even global level. NR, which also may be referred to as <NUM>, is a set of enhancements to the LTE mobile standard promulgated by the Third Generation Partnership Project (3GPP). NR is designed to better support mobile broadband Internet access by improving spectral efficiency, lowering costs, improving services, making use of new spectrum, and better integrating with other open standards using orthogonal frequency-division multiplexing (OFDM) with a cyclic prefix (CP) (CP-OFDM) on the DL, using CP-OFDM or SC-FDM (for example, also known as discrete Fourier transform spread OFDM (DFT-s-OFDM)) on the UL (or a combination thereof), as well as supporting beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation.

In accordance with the present invention, there are provided methods as set out in claims <NUM> and <NUM>, and apparatuses as set out in claims <NUM> and <NUM>. Other aspects of the invention are set out in the dependent claims. Any embodiment referred to and not falling within the scope of the claims is merely an example useful to the understanding of the invention. The systems, methods, and devices of this disclosure each have several innovative aspects, no single one of which is solely responsible for the desirable attributes disclosed herein.

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

The following description is directed to certain implementations for the purposes of describing the innovative aspects of this disclosure. However, a person having ordinary skill in the art will readily recognize that the teachings herein can be applied in a multitude of different ways. Some of the examples in this disclosure are based on wireless and wired local area network (LAN) communication according to the Institute of Electrical and Electronics Engineers (IEEE) <NUM> wireless standards, the IEEE <NUM> Ethernet standards, and the IEEE <NUM> Powerline communication (PLC) standards. However, the described implementations may be implemented in any device, system or network that is capable of transmitting and receiving radio frequency signals according to any of the wireless communication standards, including any of the IEEE <NUM> standards, the Bluetooth® standard, code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), Global System for Mobile communications (GSM), GSM/General Packet Radio Service (GPRS), Enhanced Data GSM Environment (EDGE), Terrestrial Trunked Radio (TETRA), Wideband-CDMA (W-CDMA), Evolution Data Optimized (EV-DO), 1xEV-DO, EV-DO Rev A, EV-DO Rev B, High Speed Packet Access (HSPA), High Speed Downlink Packet Access (HSDPA), High Speed Uplink Packet Access (HSUPA), Evolved High Speed Packet Access (HSPA+), Long Term Evolution (LTE), AMPS, or other known signals that are used to communicate within a wireless, cellular or internet of things (IOT) network, such as a system utilizing <NUM>, <NUM> or <NUM>, or further implementations thereof, technology.

Some radio access technologies (RATs), such as NR, may allow operation in unlicensed spectrum. The NR RAT for the unlicensed spectrum may be referred to as NR-Unlicensed (NR-U or NRU). Some RATs may support different bandwidths for sub-bands or combinations of sub-bands, such as <NUM>, <NUM>, <NUM>, <NUM>, or further examples. For example, multiple sub-bands of <NUM> may be combined to form a larger bandwidth, referred to as a wideband. The combination of multiple sub-bands may be referred to herein as a wideband structure. A wideband structure may be a bandwidth part of the UE (that is, a configured bandwidth of the UE within which the UE may communicate on one or more sub-bands).

If a UE is configured with multiple sub-bands in the unlicensed spectrum, not all sub-bands may be available at all times. For example, some sub-bands may be occupied by other UEs, base stations, wireless nodes, or further examples. A base station or a UE may perform a listen-before-talk (LBT) operation to determine whether one or more sub-bands are available for a communication. In an LBT operation, a base station or UE may listen to a channel or a sub-band for a length of time, then may transmit an indication that the base station or UE has reserved the channel or the sub-band for a time window if no other reservation for the channel or the sub-band is received while the base station or UE is listening or if interference on the channel or the sub-band satisfies a threshold. Thus, coexistence between devices on noncentrally-scheduled channels, such as sidelink channels on the unlicensed spectrum, is enabled.

A base station may use channel state information (CSI) feedback to determine channel conditions for a channel between the base station and a UE. For example, the base station may transmit a CSI-RS to one or more UEs with certain characteristics that may be available to or determinable by the UE. Using the CSI-RS, the UE may determine CSI feedback, such as a CSI report, that indicates the channel conditions between the base station and the UE. However, in the case of unlicensed spectrum with a wideband structure, not all sub-bands configured for the CSI-RS may be available when the CSI-RS is to be transmitted. Furthermore, the UE may or may not have received information indicating which sub-bands are available at the time the CSI-RS is to be transmitted (since this information may sometimes come after the CSI-RS). Certain operations, such as rate matching around the CSI-RS and transmission or processing of the CSI-RS itself, may be hampered by this uncertainty.

Techniques and apparatuses described herein provide for the determination of whether a CSI-RS is to be transmitted, and a configuration for transmission of the CSI-RS on a wideband structure based on a result of an LBT operation regarding sub-bands of the wideband structure. For example, some techniques and apparatuses described herein provide for signaling of sub-band usage information indicating which sub-bands are available before the CSI-RS is transmitted, thus allowing the UE to determine whether the CSI-RS will be transmitted and, if so, on which sub-bands. Furthermore, some techniques and apparatuses described herein provide rate matching configurations based on whether sub-band usage has been received, based on which sub-bands are available, or further examples. Still further, some techniques and apparatuses described herein provide power configurations and resource element selection criteria for wideband CSI-RS and CSI feedback.

Particular implementations of the subject matter described in this disclosure can be implemented to realize one or more of the following potential advantages. By determining which sub-bands will contain a CSI-RS, and by determining power configurations of the CSI-RS, usage of CSI-RS on the wideband may be improved. Some implementations may improve resource utilization by providing rate matching configurations that are sub-band-specific, rather than an "all-or-nothing" approach where the CSI-RS is rate matched across the entire wideband or not at all. Some implementations may reduce complexity by providing an all-or-nothing approach for rate-matching the CSI-RS. Furthermore, some implementations may improve resource utilization by ensuring that sub-band usage information is provided to the UE before the CSI-RS, which may reduce uncertainty in unlicensed bands and may conserve UE resources that might otherwise be used to process a nonexistent CSI-RS. This may ensure that the UE estimates and reports an accurate channel estimate/channel quality indication to the base station, so the base station can configure the DL/UL communication parameters and resources (such as the modulation scheme, coding rate, spatial multiplexing/diversity, and so on). For example, if the UE were to wrongly assume the presence of a CSI-RS in a sub-band, the UE may transmit an erroneous CSI feedback/report, which may lead to the BS configuring communication parameters which are sub-optimal and which result in degraded performance.

<FIG> is a block diagram conceptually illustrating an example of a wireless network <NUM>. A BS is an entity that communicates with user equipment (UEs) and also may be referred to as a base station, a NR BS, a Node B, a gNB, a <NUM> node B (NB), an access point, a transmit receive point (TRP), or further examples. In 3GPP, the term "cell" can refer to a coverage area of a BS, a BS subsystem serving this coverage area, or a combination thereof, depending on the context in which the term is used.

A BS may provide communication coverage for a macro cell, a pico cell, a femto cell, another type of cell, or a combination thereof. A macro cell may cover a relatively large geographic area (for example, several kilometers in radius) and may allow unrestricted access by UEs with service subscription. A femto cell may cover a relatively small geographic area (for example, a home) and may allow restricted access by UEs having association with the femto cell (for example, UEs in a closed subscriber group (CSG)). A BS may support one or multiple (for example, three) cells.

In some examples, the BSs may be interconnected to one another as well as to one or more other BSs or network nodes (not shown) in the wireless network <NUM> through various types of backhaul interfaces, such as a direct physical connection, a virtual network, or a combination thereof using any suitable transport network.

Wireless network <NUM> also may include relay stations. A relay station is an entity that can receive a transmission of data from an upstream station (for example, a BS or a UE) and send a transmission of the data to a downstream station (for example, a UE or a BS). A relay station also may be a UE that can relay transmissions for other UEs. A relay station also may be referred to as a relay BS, a relay base station, a relay, etc..

Wireless network <NUM> may be a heterogeneous network that includes BSs of different types, for example, 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>. For example, macro BSs may have a high transmit power level (for example, <NUM> to <NUM> watts) whereas pico BSs, femto BSs, and relay BSs may have lower transmit power levels (for example, <NUM> to <NUM> watts).

The BSs also may communicate with one another, for example, directly or indirectly via a wireless or wireline backhaul.

UEs <NUM> (for example, 120a, 120b, 120c) may be dispersed throughout wireless network <NUM>, and each UE may be stationary or mobile. A UE also may 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 (for example, 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 (for example, smart ring, smart bracelet)), an entertainment device (for example, 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 (for example, remote device), or some other entity. A wireless node may provide, for example, connectivity for or to a network (for example, a wide area network such as Internet or a cellular network) via a wired or wireless communication link. Some UEs may be considered Internet-of-Things (IoT) devices or may be implemented as NB-IoT (narrowband internet of things) devices. UE <NUM> may be included inside a housing that houses components of UE <NUM>, such as processor components, memory components, similar components, or a combination thereof.

A RAT also may be referred to as a radio technology, an air interface, etc. A frequency also may be referred to as a carrier, a frequency channel, etc. Each frequency may support a single RAT in a given geographic area in order to avoid interference between wireless networks of different RATs.

In some examples, access to the air interface may be scheduled, where a scheduling entity (for example, a base station) allocates resources for communication among some or all devices and equipment within the scheduling entity's service area or cell.

That is, in some examples, a UE may function as a scheduling entity, scheduling resources for one or more subordinate entities (for example, one or more other UEs). A UE may function as a scheduling entity in a peer-to-peer (P2P) network, in a mesh network, or another type of network.

Thus, in a wireless communication network with a scheduled access to timefrequency resources and having a cellular configuration, a P2P configuration, and a mesh configuration, a scheduling entity and one or more subordinate entities may communicate utilizing the scheduled resources.

In some aspects, two or more UEs <NUM> (for example, shown as UE 120a and UE 120e) may communicate directly using one or more side link channels (for example, without using a base station <NUM> as an intermediary to communicate with one another). For example, the UEs <NUM> may communicate using peer-to-peer (P2P) communications, device-to-device (D2D) communications, a vehicle-to-everything (V2X) protocol (which may include a vehicle-to-vehicle (V2V) protocol, a vehicle-to-infrastructure (V2I) protocol, or similar protocol), a mesh network, or similar networks, or combinations thereof. In this case, the UE <NUM> may perform scheduling operations, resource selection operations, as well as other operations described elsewhere herein as being performed by the base station <NUM>.

<FIG> is a block diagram conceptually illustrating an example <NUM> of a base station (BS) in communication with a user equipment (UE) <NUM> in a wireless network. In some aspects, base station <NUM> and UE <NUM> may respectively be one of the base stations and one of the UEs in wireless network <NUM> of <FIG>.

At base station <NUM>, a transmit processor <NUM> may receive data from a data source <NUM> for one or more UEs, select one or more modulation and coding schemes (MCS) for each UE based on channel quality indicators (CQIs) received from the UE, process (for example, encode and modulate) the data for each UE based on the MCS(s) selected for the UE, and provide data symbols for all UEs. The transmit processor <NUM> also may process system information (for example, for semi-static resource partitioning information (SRPI), etc.) and control information (for example, CQI requests, grants, upper layer signaling, etc.) and provide overhead symbols and control symbols. The transmit processor <NUM> also may generate reference symbols for reference signals (for example, the cell-specific reference signal (CRS)) and synchronization signals (for example, the primary synchronization signal (PSS) and secondary synchronization signal (SSS)). A transmit (TX) multiple-input multiple-output (MIMO) processor <NUM> may perform spatial processing (for example, precoding) on the data symbols, the control symbols, the overhead symbols, or the reference symbols, if applicable, and may provide T output symbol streams to T modulators (MODs) 232a through 232t. Each modulator <NUM> may process a respective output symbol stream (for example, for OFDM, etc.) to obtain an output sample stream. Each modulator <NUM> may further process (for example, convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal.

At UE <NUM>, antennas 252a through 252r may receive the downlink signals from base station <NUM> or other base stations and may provide received signals to demodulators (DEMODs) 254a through 254r, respectively. Each demodulator <NUM> may condition (for example, filter, amplify, downconvert, and digitize) a received signal to obtain input samples. Each demodulator <NUM> may further process the input samples (for example, for OFDM, etc.) to obtain received symbols. A receive processor <NUM> may process (for example, demodulate and decode) the detected symbols, provide decoded data for UE <NUM> to a data sink <NUM>, and provide decoded control information and system information to a controller or processor (controller/processor) <NUM>. 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 (for example, for reports including RSRP, RSSI, RSRQ, CQI, etc.) from controller/processor <NUM>. Transmit processor <NUM> also may generate reference symbols for one or more reference signals. The symbols from transmit processor <NUM> may be precoded by a TX MIMO processor <NUM> if applicable, further processed by modulators 254a through 254r (for example, for DFT-s-OFDM, CP-OFDM, etc.), and transmitted to base station <NUM>. Receive processor <NUM> may provide the decoded data to a data sink <NUM> and the decoded control information to a controller or processor (i.e., controller/processor) <NUM>. The base station <NUM> may include communication unit <NUM> and communicate to network controller <NUM> via communication unit <NUM>. The network controller <NUM> may include communication unit <NUM>, a controller or processor (i.e., controller/processor) <NUM>, and memory <NUM>.

In some implementations, controller/processor <NUM> may be a component of a processing system. A processing system may generally refer to a system or series of machines or components that receives inputs and processes the inputs to produce a set of outputs (which may be passed to other systems or components of, for example, the UE <NUM>). For example, a processing system of the UE <NUM> may refer to a system including the various other components or subcomponents of the UE <NUM>.

The processing system of the UE <NUM> may interface with other components of the UE <NUM>, and may process information received from other components (such as inputs or signals), output information to other components, etc. For example, a chip or modem of the UE <NUM> may include a processing system, a first interface to receive or obtain information, and a second interface to output, transmit or provide information. In some cases, the first interface may refer to an interface between the processing system of the chip or modem and a receiver, such that the UE <NUM> may receive information or signal inputs, and the information may be passed to the processing system. In some cases, the second interface may refer to an interface between the processing system of the chip or modem and a transmitter, such that the UE <NUM> may transmit information output from the chip or modem. A person having ordinary skill in the art will readily recognize that the second interface also may obtain or receive information or signal inputs, and the first interface also may output, transmit or provide information.

In some implementations, controller/processor <NUM> may be a component of a processing system. A processing system may generally refer to a system or series of machines or components that receives inputs and processes the inputs to produce a set of outputs (which may be passed to other systems or components of, for example, the BS <NUM>). For example, a processing system of the BS <NUM> may refer to a system including the various other components or subcomponents of the BS <NUM>.

The processing system of the BS <NUM> may interface with other components of the BS <NUM>, and may process information received from other components (such as inputs or signals), output information to other components, etc. For example, a chip or modem of the BS <NUM> may include a processing system, a first interface to receive or obtain information, and a second interface to output, transmit or provide information. In some cases, the first interface may refer to an interface between the processing system of the chip or modem and a receiver, such that the BS <NUM> may receive information or signal inputs, and the information may be passed to the processing system. In some cases, the second interface may refer to an interface between the processing system of the chip or modem and a transmitter, such that the BS <NUM> may transmit information output from the chip or modem. A person having ordinary skill in the art will readily recognize that the second interface also may obtain or receive information or signal inputs, and the first interface also may output, transmit or provide information.

The controller/processor <NUM> of base station <NUM>, the controller/processor <NUM> of UE <NUM>, or any other component(s) of <FIG> may perform one or more techniques associated with a CSI-RS for wideband operation, as described in more detail elsewhere herein. For example, the controller/processor <NUM> of base station <NUM>, the controller/processor <NUM> of UE <NUM>, or any other component(s) (or combinations of components) of <FIG> may perform or direct operations of, for example, the process <NUM> of <FIG>, the process <NUM> of <FIG>, or other processes as described herein. The memories <NUM> and <NUM> may store data and program codes for base station <NUM> and UE <NUM>, respectively. A scheduler <NUM> may schedule UEs for data transmission on the downlink, the uplink, or a combination thereof.

The stored program codes, when executed by the controller/processor <NUM> or other processors and modules at the UE <NUM>, may cause the UE <NUM> to perform operations described with respect to the process <NUM> of <FIG> or other processes as described herein. The stored program codes, when executed by the controller/processor <NUM> or other processors and modules at the base station <NUM>, may cause the base station <NUM> to perform operations described with respect to process <NUM> of <FIG> or other processes as described herein. A scheduler <NUM> may schedule UEs for data transmission on the downlink, the uplink, or a combination thereof.

The UE <NUM> may include means for performing one or more operations described herein, such as the process <NUM> of <FIG> or other processes as described herein. In some aspects, such means may include one or more components of UE <NUM> described in connection with <FIG>. The base station <NUM> may include means for performing one or more operations described herein, such as the process <NUM> of <FIG> or other processes as described herein. In some aspects, such means may include one or more components of base station <NUM> described in connection with <FIG>.

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

<FIG> is a diagram illustrating an example <NUM> of a wideband channel state information (CSI) reference signal (RS) configuration for a periodic or semi-persistent CSI-RS. While <FIG> includes a single UE <NUM> and a single BS <NUM>, the operations described in connection with <FIG> may be performed by any two or more wireless nodes. Furthermore, the BS <NUM> may perform the operations described herein for a group of UEs <NUM>, such as UEs <NUM> in communication with the BS <NUM>.

As shown by reference number <NUM>, the BS <NUM> may transmit configuration information. For example, the configuration information may identify a CSI-RS configuration, such as for a periodic CSI-RS (P-CSI-RS) or a semi-persistent CSI-RS (SP-CSI-RS). In some aspects, the CSI-RS may be an aperiodic CSI-RS (A-CSI-RS), which is described in more detail in connection with <FIG>. In some aspects, the configuration information may include, for example, information indicating a resource allocation of the CSI-RS, information indicating a sequence used to generate the CSI-RS, or further examples. For example, the configuration information may identify a group of sub-bands on which the CSI-RS may be transmitted and on which the UE <NUM> is to process the CSI-RS. In some aspects, the UE <NUM> may determine the group of sub-bands based on a configuration of the UE <NUM>, such as a bandwidth part configuration of the UE <NUM>. In some aspects, the configuration information may include information indicating a power scaling configuration for the CSI-RS, which is described in more detail below.

In some aspects, the UE <NUM> may receive a grant for a shared channel, such as a physical downlink shared channel (PDSCH). The grant may be received on one or more sub-bands that are available for the CSI-RS, since the BS <NUM> may not grant resources on an unavailable sub-band. Thus, the UE <NUM> may determine which sub-bands are available sub-bands based on the grant. The UE <NUM> may rate match the shared channel around CSI-RS resources, as described in more detail below.

As shown by reference number <NUM>, the BS <NUM> may perform an LBT operation on a group of sub-bands. For example, the BS <NUM> may perform the LBT operation on sub-bands on which the CSI-RS is configured before transmitting the CSI-RS. The BS <NUM> may determine an LBT result for each sub-band of the group of sub-bands. The LBT result may indicate whether the corresponding sub-band is available for the CSI-RS or other communications by the BS <NUM>. A sub-band for which LBT is performed can also be called an RB set or an LBT bandwidth. For example, the LBT result for a sub-band may indicate that the sub-band is associated with an interference level that satisfies a threshold (i.e., is lower than the threshold) or that the sub-band is not associated with another reservation in a time window associated with the CSI-RS. As one example, the threshold for the interference level may be approximately -<NUM> decibel milliwatts (dBm) at an antenna of the BS <NUM>. The time window of the LBT operation may be referred to as a transmit opportunity. The BS <NUM> may provide, to the UE <NUM>, a sub-band valid indication that indicates the LBT result. For example, the BS <NUM> may provide the sub-band valid indication via DCI, medium access control signaling, or the like. A sub-band valid indication may include information indicating one or more sub-bands that are (or are not) valid for communication. For example, a sub-band valid indication may include a bitmap indicating sub-bands, LBT bandwidths, or RB sets on which communication is valid based at least in part on a channel access operation (such as based at least in part on an LBT result associated with the channel access operation).

As shown by reference number <NUM>, in some cases, not all sub-bands, of the group of sub-bands, may be available for the CSI-RS. In this case, the BS <NUM> may drop or not transmit the CSI-RS, or may perform CSI-RS transmission on the available sub-bands.

In some aspects, the BS <NUM> may not transmit the CSI-RS when at least one sub-band, of the group of sub-bands, is unavailable for the CSI-RS. This may be referred to herein as an "all-or-nothing" approach. In the all-or-nothing approach, the BS <NUM> may transmit the CSI-RS when all sub-bands of the group of sub-bands are available for the CSI-RS. This may conserve signaling resources that would otherwise be used to configure or transmit a partial CSI-RS using less than all sub-bands of the group of sub-bands, and may reduce complexity of the particular design implementation. Secondly, in an all-or-nothing approach, if a CSI-RS is not transmitted in a valid sub-band (since another sub-band is not available), the CSI-RS resources can be used for data, so that the data need not rate match around the CSI-RS resources.

In some aspects, the BS <NUM> may transmit the CSI-RS on available sub-bands of the group of sub-bands. For example, when one sub-band is unavailable and three sub-bands are available for the CSI-RS, the BS <NUM> may transmit the CSI-RS on the three-sub-bands and not on the one unavailable sub-band. This may enable the provision of CSI-RSs on partially available resources, which may improve efficiency of network utilization relative to an all-or-nothing approach.

In some aspects, the BS <NUM> may use a sequence to generate the CSI-RS. In some aspects, the BS <NUM> may modify the sequence when the CSI-RS is transmitted on a subset of sub-bands of the group of bands. As a first example, the BS <NUM> may puncture a sequence for the group of sub-bands to generate a sequence for the subset of sub-bands. In this case, if sub-bands <NUM>, <NUM>, and <NUM> are available for the CSI-RS and sub-band <NUM> is unavailable, the BS <NUM> may puncture a sequence for sub-bands <NUM>, <NUM>, <NUM>, and <NUM> at a location in the sequence corresponding to sub-band <NUM>, and may generate the CSI-RS using the punctured sequence. As used herein, puncturing a sequence may refer to dropping one or more values of the sequence that correspond to an unavailable sub-band. For example, if the sequence includes <NUM> values and a second sub-band, of four sub-bands associated with the sequence, is unavailable, the BS <NUM> may drop the twenty-first through fortieth values of the sequence, may use zero values or default values for these values, or further examples. As a second example, the BS <NUM> may use a shortened sequence based on the number of resource elements of the CSI-RS. In this example, if the sequence includes <NUM> values and a second sub-band, of four sub-bands associated with the sequence, is unavailable, the BS <NUM> may generate the CSI-RS using a <NUM>-symbol sequence. In the case of the shortened sequence, the UE <NUM> may determine sub-band usage information (using a channel occupancy time (COT) structure indicator (SI), a grant-based indication, or further examples) before the CSI-RS so that the UE <NUM> can determine the length of the shortened sequence. In some aspects, the UE <NUM> may determine the punctured sequence without determining or receiving sub-band usage information (such as by performing per-sub-band processing of the CSI-RS to determine which sub-bands are used for the CSI-RS), which may simplify processing at the UE <NUM>.

As shown by reference number <NUM>, the BS <NUM> may transmit sub-band usage information, shown here as a channel occupancy time (COT) structure indicator (SI). In some aspects, the sub-band usage information may be transmitted in another form, such as downlink control information (DCI) indicating sub-band usage, an aperiodic CSI-RS trigger, a PDSCH grant, a physical uplink shared channel grant, or further examples. The COT-SI may indicate which sub-bands of the group of sub-bands are available for the CSI-RS. For example, the COT-SI may indicate LBT results for the group of sub-bands. In some aspects, the UE <NUM> may receive the COT-SI in a control channel, such as a physical downlink control channel (PDCCH).

In some cases, the COT-SI may be transmitted before the CSI-RS. In such a case, the UE <NUM> can determine which sub-bands will be used for the CSI-RS, or whether the CSI-RS will be transmitted, before the CSI-RS's transmission time. In some aspects, the UE <NUM> may determine that a CSI-RS is present in a transmission opportunity if the COT-SI is received before the CSI-RS's transmission time. If the UE <NUM> does not receive the COT-SI before the CSI-RS's transmission time, the UE <NUM> may determine that no CSI-RS is expected in the transmission opportunity. In this case, if the BS <NUM> is unable to transmit the COT-SI before the CSI-RS's transmission time, then the BS <NUM> may not transmit the CSI-RS. This may conserve UE resources that would otherwise be used to store the CSI-RS while waiting for the COT-SI.

In some aspects, the COT-SI may be transmitted after the CSI-RS. In this case, the UE <NUM> may not know which sub-bands will be used for the CSI-RS until after the CSI-RS is received. In some aspects, the UE <NUM> may store the CSI-RS, and may process the CSI-RS after receiving the COT-SI. For example, the UE <NUM> may delay processing of the CSI-RS until after the COT-SI is received. In this case, the UE <NUM> may process the latest CSI-RS even if the COT-SI is not available (such as based on the COT-SI coming after the CSI-RS).

As shown by reference number <NUM>, the BS <NUM> may transmit the CSI-RS. For example, the BS <NUM> may transmit the CSI-RS using available sub-bands of the group of sub-bands. In some aspects, the BS <NUM> may transmit the CSI-RS in a downlink (DL) burst, such as a synchronization signal burst. As shown by reference number <NUM>, the UE <NUM> may selectively process the CSI-RS. For example, in some aspects, the UE <NUM> may process the CSI-RS based on determining that the CSI-RS is to be transmitted. The UE <NUM> may generate CSI feedback based on processing the CSI-RS.

In some aspects, the UE <NUM> may process the CSI-RS based on detecting a DL burst (such as before a COT-SI is received). For example, the UE <NUM> may individually process the CSI-RS on each sub-band of the group of sub-bands, and may validate the CSI feedback to form combined CSI feedback for the available sub-bands after the COT-SI is received. Individually processing the CSI-RS on each sub-band may be referred to as a per-sub-band processing operation. Thus, the UE <NUM> may process the CSI-RS before the COT-SI is received, and may subsequently generate CSI feedback for the available sub-bands. This may be more reliable than attempting to identify sub-bands on which a CSI-RS is present using measurements on the sub-bands.

In some aspects, the UE <NUM> may determine whether a CSI-RS is present on a sub-band based on a measurement performed by the UE <NUM>. For example, the measurement may pertain to a threshold signal-to-noise ratio (SNR) or another threshold. The UE <NUM> may identify which sub-bands include a CSI-RS, and may process the CSI-RS on the sub-bands that include the CSI-RS. This may be less resource-intensive than individually processing the CSI-RS on each sub-band, and may not use the COT-SI.

In some aspects, the UE <NUM> or the BS <NUM> may determine a power level for the CSI-RS. The power level may be based on, for example, a power spectral density (PSD) or a similar value. In some aspects, the power level may be independent of the number of sub-bands available for the CSI-RS. For example, the power level may be static over time, which may conserve resources that would otherwise be used to dynamically determine the power level. In some aspects, the power level may be based on the number of sub-bands available for the CSI-RS. For example, the power level may change over time, which may provide improved CSI-RS performance across different numbers of sub-bands. In some aspects, the power level may be independent or dependent on the number of sub-bands based on whether the CSI is a periodic CSI, a semi-persistent CSI, or an aperiodic CSI.

In some aspects, the power level may be determined based on the sub-bands that are available for the CSI-RS. In some aspects, the power level may be explicitly signaled (such as by using a transmission power reduction (TPR) value relative to a nominal power level). In some aspects, the signaling may be included in the COT-SI, or may be included in the aperiodic CSI-RS trigger. In some aspects, the BS <NUM> may be operating on many more sub-bands than the UE <NUM>, and the COT-SI signaling may be limited to a smaller set of sub-bands. In this case, explicit signaling of power levels may be beneficial for the BS <NUM> so that the power level of the CSI-RS can be adapted to the smaller set of sub-bands.

As shown by reference number <NUM>, in some aspects, the UE <NUM> may rate match a shared channel around the CSI-RS. For example, if the UE <NUM> receives a PDSCH grant on a given sub-band, then the sub-band can be considered available for the CSI-RS, since the BS <NUM> would not grant a PDSCH on an unavailable sub-band. In some aspects, the UE <NUM> may rate match the shared channel around the CSI-RS's configured resources, irrespective of whether the CSI-RS is to be received, which may conserve resources that will otherwise be used to determine whether the CSI-RS is to be received. In some aspects, when the CSI-RS is transmitted only if all sub-bands are available, the UE <NUM> may rate match around the CSI-RS when all sub-bands are available for the CSI-RS. In such a case, if the sub-band usage information is not received before the CSI-RS, then the UE <NUM> may not decode the PDSCH or may assume that the CSI-RS is not present. In some aspects, the UE <NUM> may determine whether the UE <NUM> has received the CSI-RS based on a measurement (such as an SNR measurement or further examples), and may rate match around the CSI-RS if the UE <NUM> has received the CSI-RS. In some aspects, the PDSCH grant may include an indicator of whether the UE <NUM> is to rate match around the shared channel. For example, the indicator may include a bit that indicates whether the UE <NUM> is to rate match around the CSI-RS, which may conserve resources of the UE <NUM> that would otherwise be used to determine whether to rate match around the shared channel.

As shown by reference number <NUM>, the UE <NUM> may selectively transmit CSI feedback to the BS <NUM>. For example, the UE <NUM> may transmit the CSI feedback when the UE <NUM> has determined the CSI feedback based on receiving a CSI-RS from the BS <NUM>. If no CSI-RS is received, or if the UE <NUM> determines that a CSI-RS is not to be received, the UE <NUM> may not determine or transmit CSI feedback.

<FIG> is a diagram illustrating an example <NUM> of a wideband CSI-RS configuration for an aperiodic CSI-RS. While <FIG> includes a single UE <NUM> and a single BS <NUM>, the operations described in connection with <FIG> may be performed by any two or more wireless nodes. Furthermore, the BS <NUM> may perform the operations described herein for a group of UEs <NUM>, such as several UEs <NUM> in communication with the BS <NUM>.

As shown by reference number <NUM>, the BS <NUM> may transmit configuration information for an aperiodic CSI-RS (sometimes abbreviated A-CSI-RS). The configuration information is described in more detail above in connection with <FIG>. An aperiodic CSI-RS may be associated with aperiodic CSI. The BS <NUM> may configure the UE <NUM> with one or more aperiodic CSI-RS occasions, and may indicate when the UE <NUM> is to determine and transmit CSI feedback using a trigger, described below. The UE <NUM> may not process a CSI-RS or transmit CSI feedback for a CSI-RS resource unless the UE <NUM> receives the trigger from the BS <NUM>.

In some aspects, the UE <NUM> may receive multiple, different CSI-RS configurations. For example, the UE <NUM> may receive a respective CSI-RS configuration for multiple, different sub-band combinations selected from the group of sub-bands. In this case, the trigger, described below, may correspond to a CSI-RS configuration that is to be used (such as a CSI-RS configuration corresponding to the set of available sub-bands for the CSI-RS). As an example, for <NUM> sub-bands, there may be <NUM> CSI-RS configurations.

As shown by reference number <NUM>, the BS <NUM> may perform an LBT operation on a group of sub-bands. This is described in more detail in connection with <FIG>. As shown by reference number <NUM>, in some cases, not all sub-bands, of the group of sub-bands, may be available for the CSI-RS. In this case, the BS <NUM> may drop or not transmit the CSI-RS, or may perform CSI-RS transmission on the available sub-band(s). When the BS <NUM> determines that CSI-RS transmission is to be performed on the available sub-band(s), the BS <NUM> may transmit a trigger for the CSI-RS, as shown by reference number <NUM>.

In some aspects, the BS <NUM> may transmit the trigger based on the LBT result indicating that all sub-bands of the group of sub-bands are available. This may conserve resources that would otherwise be used to provide sub-band usage information to the UE <NUM>, since the UE <NUM> will not receive a trigger unless all sub-bands are available for the CSI-RS.

In some aspects, the BS <NUM> may transmit the trigger when a subset of sub-bands of the group of sub-bands are available. For example, the BS <NUM> may transmit the trigger when less than all sub-bands, of the group of sub-bands, are available for the CSI-RS. In some aspects, the BS <NUM> may transmit the trigger after transmitting the sub-band usage information shown by reference number <NUM>, and the UE <NUM> may determine which sub-bands contain the CSI-RS using the sub-band usage information. In this case, the BS <NUM> may provide a gap between the trigger and the sub-band usage information that is sufficient for the UE <NUM> to decode the sub-band usage information. This may be based on UE capabilities or other information regarding the UE <NUM>.

In some aspects, the trigger may include information indicating which sub-bands are available for the CSI-RS. For example, the configuration information shown by reference number <NUM> may configure some CSI-RS parameters, and the trigger may indicate a bandwidth of the CSI-RS, a set of sub-bands used for the CSI-RS, or further examples. Thus, the BS <NUM> may indicate which sub-bands are to be used for the CSI-RS using the trigger, which conserves resources that would otherwise be used to transmit a COT-SI.

As shown by reference number <NUM>, the BS <NUM> may transmit the CSI-RS. In some aspects, the BS <NUM> may generate the CSI-RS based on a sequence, as is described in more detail in connection with <FIG>. For example, the sequence may be punctured for unavailable sub-bands, or may be shortened for unavailable sub-bands, as is also described in more detail in connection with <FIG>.

As shown by reference number <NUM>, the UE <NUM> may selectively process the CSI-RS, as described in more detail above in connection with <FIG>. As shown by reference number <NUM>, the UE <NUM> may rate match a shared channel around the CSI-RS. As shown by reference number <NUM>, the UE <NUM> may selectively transmit CSI feedback to the BS <NUM>. These operations are also described in more detail in connection with <FIG>.

<FIG> is a diagram illustrating an example <NUM> of a CSI-RS configuration in which a CSI-RS is transmitted on available sub-bands and not on unavailable sub-bands. As shown, example <NUM> includes Sub-bands <NUM> through <NUM>. As further shown, Sub-bands <NUM>, <NUM>, and <NUM> are available and Sub-band <NUM> is unavailable. The COT-SI for example <NUM> is shown by reference number <NUM>. The COT-SI may indicate that Sub-bands <NUM>, <NUM>, and <NUM> are available and Sub-band <NUM> is unavailable. In some aspects, the COT-SI may be configured to be transmitted before the CSI-RS, as described elsewhere herein. For example, the CSI-RS may not be transmitted unless the CSI-RS is preceded by the COT-SI, thereby enabling the UE <NUM> to determine which sub-bands are available for the CSI-RS. As shown by reference number <NUM>, the BS <NUM> may not transmit the CSI-RS in Sub-band <NUM>. Furthermore, the BS <NUM> may transmit the CSI-RS in Sub-bands <NUM>, <NUM>, and <NUM>.

<FIG> is a diagram illustrating an example <NUM> of a CSI-RS configuration in which a CSI-RS is not transmitted when any sub-band is unavailable. As shown in <FIG>, the CSI-RS is not transmitted on any sub-band based on Sub-band <NUM> being unavailable. For example, reference number <NUM> shows that the LBT operation has failed in Sub-band <NUM>, and reference numbers <NUM>, <NUM>, and <NUM> show that the LBT operation has succeeded in Sub-bands <NUM>, <NUM>, and <NUM>, respectively. Since the LBT operation failed in at least one of the sub-bands shown in example <NUM>, the CSI-RS is not transmitted on any of the four sub-bands, as shown by reference number <NUM>. This implementation is referred to as the all-or-nothing approach.

<FIG> is a diagram illustrating an example <NUM> of resource element selection for a wideband CSI-RS. A transmitter may enforce a guard band for a bandwidth, meaning that resource elements at the edge of the bandwidth are not usable by the transmitter based on regulatory rules. This may reduce interference and help to manage the power spectral density (PSD) of the air interface. The width of the guard band may be based on a bandwidth of the channel. For example, a wider bandwidth may be associated with wider guard bands. In example <NUM> generally, each rectangle corresponds to a sub-band or a wideband structure composed of multiple sub-bands. Guard bands are indicated by dashed lines, where the area between a dashed line and the edge of the sub-band is the guard band. For example, the guard bands for Sub-band <NUM> are between the dashed lines shown by reference numbers <NUM> and <NUM> and the respective edges of Sub-band <NUM>, and the guard bands for a <NUM> wideband structure formed from Sub-bands <NUM> and <NUM> are between the dashed lines shown by reference numbers <NUM> and <NUM> and the respective outer edges of Sub-bands <NUM> and <NUM>. It can be seen that the guard bands for the <NUM> wideband structure are wider than for the <NUM> wideband structure.

The CSI-RS described in connection with <FIG> may be based on a sequence associated with the <NUM> wideband structure shown by reference number <NUM>. More generally, the CSI-RS for a group of sub-bands may be based on a sequence associated with a widest bandwidth structure that can be formed using the group of sub-bands. However, the guard bands for the smaller bandwidths, such as those shown by <NUM> through <NUM>, may be smaller than for the wideband structure <NUM>. This may mean that some resource elements of the smaller bandwidths or the intermediate bandwidths (such as <NUM> and <NUM>) fall outside of the usable region of the wideband structure, which reduces flexibility and which may lead to non-conformant transmission if such resource elements are used for the CSI-RS on the wideband structure.

The BS <NUM> may use resource elements that are usable for the wideband structure shown by reference number <NUM>, irrespective of which set of sub-bands is actually used for the CSI-RS. In other words, the BS <NUM> may use resource elements of the set of sub-bands that intersect with the resource elements of the wideband structure <NUM>, and may truncate resource elements that do not intersect with the resource elements of the wideband structure. Referring now to <FIG>, the guard bands of the wideband structure <NUM> are shown by reference numbers <NUM> and <NUM>. Thus, the smaller-bandwidth sets of sub-bands, shown by reference numbers <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>, do not use resource elements in the guard bands of the wideband structure. The bandwidth of the usable resource elements for the <NUM> bandwidth Sub-band <NUM><NUM> in this configuration is shown by reference number <NUM>. It can be seen that the left side of Sub-band <NUM><NUM>'s bandwidth ends at the guard band <NUM> of the wideband structure rather than at the guard band for the <NUM> bandwidth. In some examples, such as for a <NUM> subcarrier spacing, the number of usable resource elements of Sub-band <NUM> may be <NUM> x <NUM> resource elements, or <NUM> resource blocks. In some other examples, the number of usable resource elements for the sub-bands may be <NUM> x <NUM> resource elements, or <NUM> resource blocks, so as to make each of the sub-bands identical. Similar illustrations of bandwidth for the <NUM> bandwidth and the <NUM> bandwidth are shown by reference numbers <NUM> and <NUM>, respectively. Thus, by confining the resource elements of the smaller bandwidths to those that intersect with resource elements within the usable bandwidth of the wideband structure <NUM>, the CSI-RS sequence can be mapped more simply to the smaller bandwidths, since the same sequence can be used for a given resource element in the sub-band case and in the wideband structure case.

<FIG> is a diagram illustrating an example process <NUM> performed, for example, by a UE. The process <NUM> shows where a UE (such as UE <NUM>) performs operations associated with CSI feedback for wideband operation.

As shown in <FIG>, in some aspects, the process <NUM> may include receiving configuration information for a channel state information reference signal (CSI-RS), where the configuration information indicates that the CSI-RS is configured on a plurality of sub-bands of a wideband structure (block <NUM>). For example, the UE or an interface of the UE (using antenna <NUM>, DEMOD <NUM>, MIMO detector <NUM>, receive processor <NUM>, controller/processor <NUM>) may receive configuration information for a CSI-RS. The configuration information may indicate that the CSI-RS is configured on a plurality of sub-bands of a wideband structure.

As shown in <FIG>, in some aspects, the process <NUM> may include selectively receiving the CSI-RS based on the configuration information and based on a sub-band valid indication associated with the plurality of sub-bands (block <NUM>). For example, the UE or an interface of the UE (such as using antenna <NUM>, DEMOD <NUM>, MIMO detector <NUM>, receive processor <NUM>, or controller/processor <NUM>) may selectively receive the CSI-RS based on the configuration information and based on a sub-band valid indication associated with the plurality of sub-bands.

As shown in <FIG>, in some aspects, the process <NUM> may include, if the CSI-RS is received, transmitting channel state information (CSI) feedback based on the configuration information (block <NUM>). For example, if the CSI-RS is received, the UE or an interface of the UE (using antenna <NUM>, DEMOD <NUM>, MIMO detector <NUM>, receive processor <NUM>, controller/processor <NUM>) may transmit channel state information (CSI) feedback based on the configuration information.

The process <NUM> may include additional aspects, such as any single aspect or any combination of aspects described below or in connection with one or more other processes described elsewhere herein.

In a first aspect, the process <NUM> may include receiving downlink control information indicating the sub-band valid indication.

In a second aspect, alone or in combination with the first aspect, when all sub-bands of the plurality of sub-bands are available for the CSI-RS, the CSI-RS is received, and when at least one sub-band of the plurality of sub-bands is not available for the CSI-RS, the CSI-RS is not received.

In a third aspect, alone or in combination with one or more of the first and second aspects, the process <NUM> may include rate matching a shared channel around a resource of the CSI-RS irrespective of whether the CSI-RS is received.

In a fourth aspect, alone or in combination with one or more of the first through third aspects, the process <NUM> may include performing a processing operation associated with the CSI-RS with respect to the plurality of sub-bands irrespective of whether the CSI-RS is received.

In a fifth aspect, alone or in combination with one or more of the first through fourth aspects, the process <NUM> may include determining that the CSI-RS is to be received based on sub-band usage information received before a resource associated with the CSI-RS; and performing a processing operation associated with the CSI-RS with respect to the plurality of sub-bands based on determining that the CSI-RS is to be received.

In a sixth aspect, alone or in combination with one or more of the first through fifth aspects, the CSI-RS is received on a subset of sub-bands of the plurality of sub-bands based on the subset of sub-bands being available for the CSI-RS.

In a seventh aspect, alone or in combination with one or more of the first through sixth aspects, a sequence for the CSI-RS for the plurality of sub-bands is punctured to generate the CSI-RS for the subset of sub-bands.

In an eighth aspect, alone or in combination with one or more of the first through seventh aspects, In some implementations, the CSI-RS for the subset of sub-bands is generated based on a shortened sequence relative to a sequence for the CSI-RS for the plurality of sub-bands.

In a ninth aspect, alone or in combination with one or more of the first through eighth aspects, the process <NUM> may include receiving a trigger for the CSI feedback based on all sub-bands, of the plurality of sub-bands, being available for the CSI-RS.

In a tenth aspect, alone or in combination with one or more of the first through ninth aspects, when the CSI-RS is received on a subset of sub-bands, of the plurality of sub-bands, the CSI-RS is received on resource elements on the subset of sub-bands that correspond to a widest bandwidth of the wideband structure.

In an eleventh aspect, alone or in combination with one or more of the first through tenth aspects, the CSI-RS is generated based on a same sequence with respect to the widest bandwidth and with respect to the subset of sub-bands.

In a twelfth aspect, alone or in combination with one or more of the first through eleventh aspects, the CSI-RS spans <NUM> resource blocks in a sub-band of the subset of sub-bands.

In a thirteenth aspect, alone or in combination with one or more of the first through twelfth aspects, the resource elements intersect with resource elements of the wideband structure.

In a fourteenth aspect, alone or in combination with one or more of the first through thirteenth aspects, the process <NUM> may include receiving a trigger for the CSI feedback after a COT-SI indicating a subset of sub-bands, of the plurality of sub-bands, that are available for the CSI-RS.

In a fifteenth aspect, alone or in combination with one or more of the first through fourteenth aspects, the CSI-RS is for periodic or semi-persistent CSI feedback.

In a sixteenth aspect, alone or in combination with one or more of the first through fifteenth aspects, the CSI-RS is for aperiodic CSI feedback.

In a seventeenth aspect, alone or in combination with one or more of the first through sixteenth aspects, the process <NUM> may include rate matching a shared channel around a resource of the CSI-RS based on the plurality of sub-bands being available for the CSI-RS.

In an eighteenth aspect, alone or in combination with one or more of the first through seventeenth aspects, the process <NUM> may include selectively receiving the CSI-RS based on at least one of: a COT-SI received before a resource of the CSI-RS, a signal-to-noise ratio associated with a resource of the CSI-RS, or a value associated with a grant for a shared channel.

In a nineteenth aspect, alone or in combination with one or more of the first through eighteenth aspects, the process <NUM> may include performing a processing operation associated with the CSI-RS with respect to the plurality of sub-bands based on a COT-SI received after the CSI-RS is received.

In a twentieth aspect, alone or in combination with one or more of the first through nineteenth aspects, the process <NUM> may include performing a per-sub-band processing operation associated with the CSI-RS to determine per-sub-band CSI feedback; and identifying a subset of sub-bands, of the plurality of sub-bands, on which the CSI-RS is received, where the CSI feedback is based on the per-sub-band CSI feedback associated with the subset of sub-bands.

In a twenty-first aspect, alone or in combination with one or more of the first through twentieth aspects, the process <NUM> may include receiving a grant for a subset of sub-bands of the plurality of sub-bands; and rate matching a shared channel associated with the grant around a resource associated with the CSI-RS on the subset of sub-bands.

In a twenty-second aspect, alone or in combination with one or more of the first through twenty-first aspects, the process <NUM> may include receiving a grant for a subset of sub-bands of the plurality of sub-bands; and rate matching a shared channel associated with the grant around a resource associated with the CSI-RS on the subset of sub-bands based on a COT-SI being received before the CSI-RS, where the COT-SI indicates that the subset of sub-bands are available.

In a twenty-third aspect, alone or in combination with one or more of the first through twenty-second aspects, the CSI-RS is received on a subset of sub-bands.

In a twenty-fourth aspect, alone or in combination with one or more of the first through twenty-third aspects, the configuration information includes configurations for multiple different subsets of sub-bands of the plurality of sub-bands.

In a twenty-fifth aspect, alone or in combination with one or more of the first through twenty-fourth aspects, the process <NUM> may include receiving a trigger associated with a configuration for a particular subset of sub-bands, of the multiple different subsets of sub-bands, based on the particular subset of sub-bands being available for the CSI-RS.

In a twenty-sixth aspect, alone or in combination with one or more of the first through twenty-fifth aspects, the process <NUM> may include receiving a trigger that indicates a particular subset of sub-bands, of the multiple different subsets of sub-bands, based on the particular subset of sub-bands being available for the CSI-RS.

In a twenty-seventh aspect, alone or in combination with one or more of the first through twenty-sixth aspects, a power level of the CSI-RS, per resource element or per sub-band, is independent of a number of sub-bands on which the CSI-RS is transmitted.

In a twenty-eighth aspect, alone or in combination with one or more of the first through twenty-seventh aspects, a power level of the CSI-RS, per resource element or per sub-band, is based on a number or configuration of sub-bands on which the CSI-RS is transmitted.

In a twenty-ninth aspect, alone or in combination with one or more of the first through twenty-eighth aspects, a power level of the CSI-RS is based on whether the CSI-RS is aperiodic, periodic, or semi-persistent.

In a thirtieth aspect, alone or in combination with one or more of the first through twenty-ninth aspects, the process <NUM> may include determining a power level of the CSI-RS based on at least one of: a number or configuration of sub-bands on which the CSI-RS is transmitted, or information indicating the power level of the CSI-RS.

Although <FIG> shows example blocks of the process <NUM>, in some aspects, the process <NUM> may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in <FIG>. Additionally, or alternatively, two or more of the blocks of the process <NUM> may be performed in parallel.

<FIG> is a diagram illustrating an example process <NUM> performed, for example, by a BS. The process <NUM> shows where a base station, such as base station <NUM>, performs operations associated with CSI-RS transmission on a wideband structure.

As shown in <FIG>, in some aspects, the process <NUM> may include transmitting configuration information for a CSI-RS, where the configuration information indicates a plurality of sub-bands of a wideband structure for the CSI-RS (block <NUM>). For example, the base station or an interface of the base station (using controller/processor <NUM>, transmit processor <NUM>, TX MIMO processor <NUM>, MOD <NUM>, antenna <NUM>) may transmit configuration information for a CSI-RS. In some aspects, the configuration information indicates a plurality of sub-bands of a wideband structure for the CSI-RS.

As shown in <FIG>, in some aspects, the process <NUM> may include performing a listen-before-talk (LBT) operation to identify a subset of sub-bands, of the plurality of sub-bands, that are available for the CSI-RS, where the subset of sub-bands includes up to all sub-bands of the plurality of sub-bands (block <NUM>). For example, the base station or an interface of the base station (using antenna <NUM>, DEMOD <NUM>, MIMO detector <NUM>, receive processor <NUM>, controller/processor <NUM>) may perform an LBT operation to identify a subset of sub-bands, of the plurality of sub-bands, that are available for the CSI-RS. The subset of sub-bands includes up to all sub-bands of the plurality of sub-bands.

As shown in <FIG>, in some aspects, the process <NUM> may include selectively transmitting the CSI-RS based on a result of the LBT operation (block <NUM>). For example, the base station or an interface of the base station (using controller/processor <NUM>, transmit processor <NUM>, TX MIMO processor <NUM>, MOD <NUM>, antenna <NUM>) may selectively transmit the CSI-RS based on a result of the LBT operation, as described above.

In a first aspect, when all sub-bands of the plurality of sub-bands are available for the CSI-RS, the CSI-RS is transmitted, and when at least one sub-band of the plurality of sub-bands is not available for the CSI-RS, the CSI-RS is not transmitted.

In a second aspect, alone or in combination with the first aspect, the process <NUM> may include rate matching a shared channel around a resource of the CSI-RS irrespective of whether the CSI-RS is transmitted.

In a third aspect, alone or in combination with one or more of the first and second aspects, the subset of sub-bands includes less than all sub-bands of the plurality of sub-bands.

In a fourth aspect, alone or in combination with one or more of the first through third aspects, a sequence for the CSI-RS for the plurality of sub-bands is punctured to generate the CSI-RS for the subset of sub-bands.

In a fifth aspect, alone or in combination with one or more of the first through fourth aspects, the CSI-RS for the subset of sub-bands is generated based on a shortened sequence, relative to a sequence for the CSI-RS for the plurality of sub-bands.

In a sixth aspect, alone or in combination with one or more of the first through fifth aspects, the process <NUM> may include transmitting a trigger for CSI feedback associated with the CSI-RS based on all sub-bands, of the plurality of sub-bands, being available for the CSI-RS.

In a seventh aspect, alone or in combination with one or more of the first through sixth aspects, when the CSI-RS is transmitted on the subset of sub-bands of the plurality of sub-bands, the CSI-RS is transmitted on resource elements on the subset of sub-bands that correspond to a widest bandwidth of the wideband structure.

In an eighth aspect, alone or in combination with one or more of the first through seventh aspects, the CSI-RS is based on a same sequence with respect to the widest bandwidth and with respect to the subset of sub-bands.

In a ninth aspect, alone or in combination with one or more of the first through eighth aspects, the CSI-RS spans <NUM> resource blocks in a sub-band of the subset of sub-bands.

In a tenth aspect, alone or in combination with one or more of the first through ninth aspects, the resource elements intersect with resource elements of the wideband structure.

In an eleventh aspect, alone or in combination with one or more of the first through tenth aspects, the CSI-RS is for periodic or semi-persistent CSI feedback.

In a twelfth aspect, alone or in combination with one or more of the first through eleventh aspects, the CSI-RS is for aperiodic CSI feedback.

In a thirteenth aspect, alone or in combination with one or more of the first through twelfth aspects, the process <NUM> may include rate matching a shared channel around a resource of the CSI-RS based on the plurality of sub-bands being available for the CSI-RS.

In a fourteenth aspect, alone or in combination with one or more of the first through thirteenth aspects, the process <NUM> may include transmitting sub-band usage information identifying the subset of sub-bands, where the sub-band usage information identifying the subset of sub-bands is associated with at least one of: a COT-SI transmitted before a resource of the CSI-RS, a value associated with a grant for a shared channel, or downlink control information that indicates the subset of sub-bands.

In a fifteenth aspect, alone or in combination with one or more of the first through fourteenth aspects, the process <NUM> may include transmitting a grant for the subset of sub-bands; and rate matching a shared channel associated with the grant around a resource associated with the CSI-RS on the subset of sub-bands.

In a sixteenth aspect, alone or in combination with one or more of the first through fifteenth aspects, the process <NUM> may include transmitting a grant for the subset of sub-bands; transmitting a COT-SI before the CSI-RS; and rate matching a shared channel associated with the grant around a resource associated with the CSI-RS on the subset of sub-bands based on the COT-SI being transmitted before the CSI-RS.

In a seventeenth aspect, alone or in combination with one or more of the first through sixteenth aspects, the process <NUM> may include transmitting a trigger for CSI feedback associated with the CSI-RS after a COT-SI indicating the subset of sub-bands, of the plurality of sub-bands, that are available for the CSI-RS.

In an eighteenth aspect, alone or in combination with one or more of the first through seventeenth aspects, the configuration information includes configurations for multiple different subsets of sub-bands of the plurality of sub-bands.

In a nineteenth aspect, alone or in combination with one or more of the first through eighteenth aspects, the process <NUM> may include transmitting a trigger associated with a configuration for a particular subset of sub-bands, of the multiple different subsets of sub-bands, based on the particular subset of sub-bands being available for the CSI-RS.

In a twentieth aspect, alone or in combination with one or more of the first through nineteenth aspects, the process <NUM> may include transmitting a trigger that indicates a particular subset of sub-bands, of the multiple different subsets of sub-bands, based on the particular subset of sub-bands being available for the CSI-RS.

In a twenty-first aspect, alone or in combination with one or more of the first through twentieth aspects, a power level of the CSI-RS, per resource element or per sub-band, is independent of a number of sub-bands on which the CSI-RS is transmitted.

In a twenty-second aspect, alone or in combination with one or more of the first through twenty-first aspects, a power level of the CSI-RS, per resource element or per sub-band, is based on a number or configuration of sub-bands on which the CSI-RS is transmitted.

In a twenty-third aspect, alone or in combination with one or more of the first through twenty-second aspects, a power level of the CSI-RS, per resource element or per sub-band, is based on whether the CSI-RS is aperiodic, periodic, or semi-persistent.

In a twenty-fourth aspect, alone or in combination with one or more of the first through twenty-third aspects, the process <NUM> may include determining a power level of the CSI-RS based on at least one of: a number or configuration of sub-bands on which the CSI-RS is transmitted, or information indicating the power level of the CSI-RS.

In a twenty-fifth aspect, alone or in combination with one or more of the first through twenty-fourth aspects, the CSI-RS is transmitted when a COT-SI associated with the CSI-RS can be transmitted before the CSI-RS, and where the CSI-RS is not transmitted when the COT-SI associated with the CSI-RS cannot be transmitted before the CSI-RS.

As used herein, the phrase "based on" is intended to be broadly construed to mean "based on.

The various illustrative logics, logical blocks, modules, circuits and algorithm processes described in connection with the aspects disclosed herein may be implemented as electronic hardware, computer software, or combinations of both.

The hardware and data processing apparatus used to implement the various illustrative logics, logical blocks, modules and circuits described in connection with the aspects disclosed herein may be implemented or performed with a general purpose single- or multi-chip processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (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, or, any conventional processor, controller, microcontroller, or state machine. A processor also may be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a group of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. In some aspects, particular processes and methods may be performed by circuitry that is specific to a given function.

Aspects of the subject matter described in this specification also can be implemented as one or more computer programs, i.e., one or more modules of computer program instructions, encoded on a computer storage media for execution by, or to control the operation of, data processing apparatus.

Various modifications to the aspects described in this disclosure may be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects without departing from the scope of this disclosure. Thus, the claims are not intended to be limited to the aspects shown herein, but are to be accorded the widest scope consistent with this disclosure, the principles and the novel features disclosed herein.

Certain features that are described in this specification in the context of separate aspects also can be implemented in combination in a single aspect. Conversely, various features that are described in the context of a single aspect also can be implemented in multiple aspects separately or in any suitable subcombination.

Claim 1:
A method (<NUM>) of wireless communication performed by an apparatus of a user equipment, UE, comprising:
receiving (<NUM>) configuration information for a channel state information reference signal, CSI-RS,
wherein the configuration information indicates that the CSI-RS is configured on a plurality of sub-bands of a wideband structure;
selectively receiving (<NUM>) the CSI-RS based on the configuration information and based on a sub-band valid indication associated with the plurality of sub-bands, wherein the sub-band valid indication indicates a listen-before-talk, LBT, result on the plurality of sub-bands performed by an apparatus of a base station
wherein, when all sub-bands of the plurality of sub-bands are available for the CSI-RS, the CSI-RS is received, and when at least one sub-band of the plurality of sub-bands is not available for the CSI-RS, the CSI-RS is not received; and
if the CSI-RS is received (<NUM>), transmitting channel state information, CSI, feedback based on the configuration information.