Patent Description:
The following relates generally to wireless communication, and more specifically to communication schemes for small cyclic delay diversity (SCDD) reference signals.

In some wireless communication systems, a transmitting device, such as a base station, may use SCDD by introducing a delay or a small phase offset in a signal sent using a second virtual antenna as compared to signal sent using a first virtual antenna. SCDD may serve to optimize wideband channel estimation and transmissions for high mobility UEs. However, to achieve accurate channel estimation or spectral efficiency, a UE may perform calculations that depend on the phase offset. Due to the phase offset variances in SCDD, CSI feedback estimation by a UE may be difficult or inaccurate. <CIT> describes method for reporting channel state information. <CIT> describes in one embodiment a method for reporting an offset between antennas. In a second embodiment CSI feedback is transmitted while compensating for an offset between antennas.

The described techniques relate to improved methods, systems, devices, or apparatuses that support communication schemes for small cyclic delay diversity (SCDD) reference signals. Generally the described techniques provide for flexible application of a time offset indication for derivation of channel state information (CSI). For example, the time or phase offset may be configured by the network, a user equipment (UE), or a combination thereof. Further, the techniques may involve configuration of the time or phase offset based on a class associated with a channel property or a CSI reference signal (CSI-RS) transmission and may be used to improve CSI derivation and feedback.

A method of wireless communication is described. The method may include receiving, from a base station, a control message comprising at least one CSI configuration parameter, identifying, by a UE, a time offset between a plurality of virtual antennas of the base station based at least in part on the at least one CSI configuration parameter, performing, by the UE, measurements of a plurality of CSI-RSs associated with the plurality of virtual antennas of the base station, and transmitting, to the base station, a feedback message based at least in part on the identified time offset and the measurements of the plurality of CSI-RSs.

An apparatus for wireless communication is described. The apparatus may include means for receiving, from a base station, a control message comprising at least one CSI configuration parameter, means for identifying, by a UE, a time offset between a plurality of virtual antennas of the base station based at least in part on the at least one CSI configuration parameter, means for performing, by the UE, measurements of a plurality of CSI-RSs associated with the plurality of virtual antennas of the base station, and means for transmitting, to the base station, a feedback message based at least in part on the identified time offset and the measurements of the plurality of CSI-RSs.

Another apparatus for wireless communication is described. The apparatus may include a processor, memory in electronic communication with the processor, and instructions stored in the memory. The instructions may be operable to cause the processor to receive, from a base station, a control message comprising at least one CSI configuration parameter, identify, by a UE, a time offset between a plurality of virtual antennas of the base station based at least in part on the at least one CSI configuration parameter, perform, by the UE, measurements of a plurality of CSI-RSs associated with the plurality of virtual antennas of the base station, and transmit, to the base station, a feedback message based at least in part on the identified time offset and the measurements of the plurality of CSI-RSs.

A non-transitory computer readable medium for wireless communication is described. The non-transitory computer-readable medium may include instructions operable to cause a processor to receive, from a base station, a control message comprising at least one CSI configuration parameter, identify, by a UE, a time offset between a plurality of virtual antennas of the base station based at least in part on the at least one CSI configuration parameter, perform, by the UE, measurements of a plurality of CSI-RSs associated with the plurality of virtual antennas of the base station, and transmit, to the base station, a feedback message based at least in part on the identified time offset and the measurements of the plurality of CSI-RSs.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, identifying the time offset comprises: calculating the time offset based at least in part on the at least one CSI configuration parameter.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, transmitting the feedback message further comprises: transmitting an initial co-phase vector between the plurality of virtual antennas of the base station.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, identifying the time offset comprises: receiving an indication of a time offset configuration from the base station, the time offset configuration determined by one of a core network node or the base station.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the indication may be received via DCI or a radio resource control (RRC) message.

Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for computing CSI feedback for at least one CSI-RS based at least in part on the time offset configuration, wherein the feedback message includes the computed CSI feedback.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the control message comprises DCI from the base station, the DCI comprising the at least one CSI configuration parameter.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, a format of the DCI comprises at least one of a special DCI format or a DCI format for CSI-RS.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the DCI may be for the UE or a group of UEs including the UE.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the control message comprises an RRC message comprising the at least one CSI configuration parameter.

Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for determining a fixed value of the time offset for use in performing the measurements, wherein the feedback message may be based at least in part on the fixed value of the time offset.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, determining the time offset comprises: selecting the time offset from a set of time offset candidates based at least in part on the measurements of the plurality of CSI-RSs.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the time offset candidates may be determined based at least in part on the control message.

Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for determining, based at least in part on the time offset, at least one CSI parameter from a group consisting of: a rank indicator (RI), an initial co-phase indicator, a precoder matrix indicator (PMI), and a channel quality indicator (CQI), wherein the determined at least one CSI parameter may be included in the feedback message.

Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for selecting, based on a determination that the time offset equals <NUM> or a determination that a selected CSI resource corresponds to the time offset equal to <NUM>, a closed loop transmission scheme procedure for transmitting the feedback message.

A method of wireless communication is described. The method may include transmitting, by a base station, a control message comprising at least one CSI configuration parameter and a request to report a time offset between a plurality of virtual antennas of the base station and measurements of a plurality of CSI-RSs associated with the plurality of virtual antennas of the base station and receiving, from a UE and in response to the request, a feedback message based at least in part on the time offset and the measurements of the plurality of CSI-RSs.

An apparatus for wireless communication is described. The apparatus may include means for transmitting, by a base station, a control message comprising at least one CSI configuration parameter and a request to report a time offset between a plurality of virtual antennas of the base station and measurements of a plurality of CSI-RSs associated with the plurality of virtual antennas of the base station and means for receiving, from a UE and in response to the request, a feedback message based at least in part on the time offset and the measurements of the plurality of CSI-RSs.

Another apparatus for wireless communication is described. The apparatus may include a processor, memory in electronic communication with the processor, and instructions stored in the memory. The instructions may be operable to cause the processor to transmit, by a base station, a control message comprising at least one CSI configuration parameter and a request to report a time offset between a plurality of virtual antennas of the base station and measurements of a plurality of CSI-RSs associated with the plurality of virtual antennas of the base station and receive, from a UE and in response to the request, a feedback message based at least in part on the time offset and the measurements of the plurality of CSI-RSs.

A non-transitory computer readable medium for wireless communication is described. The non-transitory computer-readable medium may include instructions operable to cause a processor to transmit, by a base station, a control message comprising at least one CSI configuration parameter and a request to report a time offset between a plurality of virtual antennas of the base station and measurements of a plurality of CSI-RSs associated with the plurality of virtual antennas of the base station and receive, from a UE and in response to the request, a feedback message based at least in part on the time offset and the measurements of the plurality of CSI-RSs.

Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for transmitting, to the UE, an indication of a time offset configuration, the time offset configuration determined by one of a core network node or the base station.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the indication may be transmitted via DCI, an RRC message, or within the control message.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the feedback message includes CSI feedback for at least one CSI-RS of the plurality of CSI-RSs based at least in part on the time offset configuration.

Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for configuring a set of time offset candidates for the UE, wherein the control message includes the set of time offset candidates.

Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for receiving, from the UE, a UE time offset and at least one CSI parameter based at least in part on the UE time offset, wherein the at least one CSI parameter may be included in the feedback message.

Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for receiving, from the UE, at least one CSI parameter based at least in part on a fixed time offset, wherein the at least one CSI parameter may be included in the feedback message.

Because of the lossy channels in wireless communication systems, a transmitting device, such as a base station, may employ small cyclic delay diversity (SCDD) to mitigate path loss. SCDD introduces a time offset between a first signal transmitted by a first virtual antenna and a second signal transmitted by a second virtual antenna. In some cases, the time offset may be denoted by τ, and the virtual antennas may each be beamformed transmissions performed by one or more physical antennas. Further, the beamformed transmissions may be formed by more than two virtual antennas, each of which may be associated with an individual virtual antenna index (e.g., <NUM>, <NUM>, <NUM>, <NUM>,. In such instances, SCDD may introduce a first time offset (e.g., τ<NUM>) between a first signal transmitted by the first virtual antenna (virtual antenna index <NUM>) and a second signal transmitted by the second virtual antenna (virtual antenna index <NUM>), a second offset (e.g., τ<NUM>) between the second signal transmitted by the second virtual antenna (virtual antenna index <NUM>) and a third signal transmitted by the third virtual antenna (virtual antenna index <NUM>), and so on. In some cases, the multiple time offsets (e.g., τ<NUM>, τ<NUM>,. ) introduced between the virtual antennas may be the same or different. In some systems, increasing the number of antennas at a base station may be less complex than at a user equipment (UE) (e.g., due to size and power constraints). In such instances, when a base station supports more physical antennas than a UE, the base station may map a relatively large number of physical antennas to a smaller number of virtual antennas and may utilize SCDD during transmission of one or more signals to the UE.

The time offset introduced by SCDD may result in a phase offset in frequency tones. To accurately derive a Channel Quality Indicator (CQI), it may be beneficial for a UE to be aware of the phase offset. Further, the phase offset may be flexibly chosen (e.g., by the base station) based at least in part on a transmission configuration or may be adjusted based on channel conditions, UE capabilities, etc. In some examples, it may be desirable to align the Channel State Information (CSI) feedback mechanism for SCDD with the CSI feedback designed for transmission as closely as possible so the UE may determine the time offset between multiple virtual antennas of the base station. The time offset may be indicated to the UE from a base station or other network node or the UE may calculate the time offset based on a control message received from the base station. The UE may also perform measurements of multiple CSI reference signals (RSs) transmitted from the base station. Using the determined time offset along with the measurements, the UE may transmit a feedback message to the base station.

Aspects of the disclosure are initially described in the context of a wireless communications system. Aspects are then described with respect to process flows. Aspects of the disclosure are further illustrated by and described with reference to apparatus diagrams, system diagrams, and flowcharts that relate to CSI feedback designs for SCDD.

<FIG> illustrates an example of a wireless communications system <NUM> in accordance with various aspects of the present disclosure. The wireless communications system <NUM> includes base stations <NUM>, UEs <NUM>, and a core network <NUM>. In some examples, the wireless communications system <NUM> may be a Long Term Evolution (LTE) network, LTE-Advanced (LTE-A) network, or a New Radio (NR) network. In some cases, wireless communications system <NUM> may support enhanced broadband communications, ultra-reliable (i.e., mission critical) communications, low latency communications, and communications with low-cost and low-complexity devices. In the wireless communications system <NUM>, a base station <NUM> may employ SCDD which may involve introducing a time or phase offset between RSs transmitted using multiple antenna ports of the base station <NUM>. A UE <NUM> may receive the RSs and perform measurements of the RSs to provide feedback to the base station <NUM>. In some instances, the UE <NUM> may determine or receive an indication of the time offset (e.g., from base station <NUM>), which may be used to determine one or more CSI parameters. The one or more CSI parameters may be transmitted in the feedback message to the UE <NUM>.

Each base station <NUM> may provide communication coverage for a respective geographic coverage area <NUM>. Control information and data may be multiplexed on an uplink channel or downlink according to various techniques. Control information and data may be multiplexed on a downlink channel, for example, using time division multiplexing (TDM) techniques, frequency division multiplexing (FDM) techniques, or hybrid TDM-FDM techniques. In some examples, the control information transmitted during a transmission time interval (TTI) of a downlink channel may be distributed between different control regions in a cascaded manner (e.g., between a common control region and one or more UE-specific control regions).

A UE <NUM> may also be referred to as a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology. A UE <NUM> may also be a cellular phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a tablet computer, a laptop computer, a cordless phone, a personal electronic device, a handheld device, a personal computer, a wireless local loop (WLL) station, an Internet of Things (IoT) device, an Internet of Everything (IoE) device, a machine type communication (MTC) device, an appliance, an automobile, or the like.

One or more of a group of UEs <NUM> utilizing D2D communications may be within the geographic coverage area <NUM> of a cell. Other UEs <NUM> in such a group may be outside the geographic coverage area <NUM> of a cell, or otherwise unable to receive transmissions from a base station <NUM>.

Examples of applications for MTC devices include smart metering, inventory monitoring, water level monitoring, equipment monitoring, healthcare monitoring, wildlife monitoring, weather and geological event monitoring, fleet. management and tracking, remote security sensing, physical access control, and transaction-based business charging.

In some cases, an MTC device may operate using half-duplex (one-way) communications at a reduced peak rate. MTC devices may also be configured to enter a power saving "deep sleep" mode when not engaging in active communications. In some cases, MTC or IoT devices may be designed to support mission critical functions and wireless communications system may be configured to provide ultra-reliable communications for these functions.

Wireless communications system <NUM> may operate in an ultra-high frequency (UHF) frequency region using frequency bands from <NUM> to <NUM> (<NUM>), although some networks (e.g., a wireless local area network (WLAN)) may use frequencies as high as <NUM>. This region may also be known as the decimeter band, since the wavelengths range from approximately one decimeter to one meter in length. UHF waves may propagate mainly by line of sight, and may be blocked by buildings and environmental features. However, the waves may penetrate walls sufficiently to provide service to UEs <NUM> located indoors. Transmission of UHF waves is characterized by smaller antennas and shorter range (e.g., less than <NUM>) compared to transmission using the smaller frequencies (and longer waves) of the high frequency (HF) or very high frequency (VHF) portion of the spectrum. In some cases, wireless communications system <NUM> may also utilize extremely high frequency (EHF) portions of the spectrum (e.g., from <NUM> to <NUM>). This region may also be known as the millimeter band, since the wavelengths range from approximately one millimeter to one centimeter in length. Thus, EHF antennas may be even smaller and more closely spaced than UHF antennas. In some cases, this may facilitate use of antenna arrays within a UE <NUM> (e.g., for directional beamforming). However, EHF transmissions may be subject to even greater atmospheric attenuation and shorter range than UHF transmissions.

Thus, wireless communications system <NUM> may support millimeter wave (mmW) communications between UEs <NUM> and base stations <NUM>. Devices operating in mmW or EHF bands may have multiple antennas to allow beamforming. That is, a base station <NUM> may use multiple antennas or antenna arrays to conduct beamforming operations for directional communications with a UE <NUM>. Beamforming (which may also be referred to as spatial filtering or directional transmission) is a signal processing technique that may be used at a transmitter (e.g., a base station <NUM>) to shape and/or steer an overall antenna beam in the direction of a target receiver (e.g., a UE <NUM>). This may be achieved by combining elements in an antenna array in such a way that transmitted signals at particular angles experience constructive interference while others experience destructive interference.

Multiple-input multiple-output (MIMO) wireless systems use a transmission scheme between a transmitter (e.g., a base station <NUM>) and a receiver (e.g., a UE <NUM>), where both transmitter and receiver are equipped with multiple antennas. Some portions of wireless communications system <NUM> may use beamforming. For example, base station <NUM> may have an antenna array with a number of rows and columns of antenna ports that the base station <NUM> may use for beamforming in its communication with UE <NUM>. Signals may be transmitted multiple times in different directions (e.g., each transmission may be beamformed differently). A mmW receiver (e.g., a UE <NUM>) may try multiple beams (e.g., antenna subarrays) while receiving the synchronization signals.

In some cases, the antennas of a base station <NUM> or UE <NUM> may be located within one or more antenna arrays, which may support beamforming or MIMO operation. One or more base station antennas or antenna arrays may be collocated at an antenna assembly, such as an antenna tower. A base station <NUM> may multiple use antennas or antenna arrays to conduct beamforming operations for directional communications with a UE <NUM>.

The MAC layer may also use Hybrid ARQ (HARQ) to provide retransmission at the MAC layer to improve link efficiency. In the control plane, the Radio Resource Control (RRC) protocol layer may provide establishment, configuration, and maintenance of an RRC connection between a UE <NUM> and a network device such as a base station <NUM> or core network <NUM> supporting radio bearers for user plane data.

An eCC may be characterized by one or more features including: wider bandwidth, shorter symbol duration, shorter TTIs, and modified control channel configuration. An eCC may also be configured for use in unlicensed spectrum or shared spectrum (where more than one operator is allowed to use the spectrum). An eCC characterized by wide bandwidth may include one or more segments that may be utilized by UEs <NUM> that are not capable of monitoring the whole bandwidth or prefer to use a limited bandwidth (e.g., to conserve power).

A shorter symbol duration is associated with increased subcarrier spacing. A device, such as a UE <NUM> or base station <NUM>, utilizing eCCs may transmit wideband signals (e.g., <NUM>, <NUM>, <NUM>, <NUM>, etc.) at reduced symbol durations (e.g., <NUM> microseconds). A TTI in eCC may consist of one or multiple symbols. In some cases, the TTI duration (that is, the number of symbols in a TTI) may be variable.

A shared radio frequency spectrum band may be utilized in an NR shared spectrum system. For example, an NR shared spectrum may utilize any combination of licensed, shared, and unlicensed spectrums, among others. The flexibility of eCC symbol duration and subcarrier spacing may allow for the use of eCC across multiple spectrums. In some examples, NR shared spectrum may increase spectrum utilization and spectral efficiency, specifically through dynamic vertical (e.g., across frequency) and horizontal (e.g., across time) sharing of resources.

For example, wireless communications system <NUM> may employ LTE License Assisted Access (LTE-LAA) or LTE Unlicensed (LTE U) radio access technology or NR, technology in an unlicensed band such as the <NUM> Industrial, Scientific, and Medical (ISM) band. When operating in unlicensed radio frequency spectrum bands, wireless devices such as base stations <NUM> and UEs <NUM> may employ listen-before-talk (LBT) procedures to ensure the channel is clear before transmitting data. In some cases, operations in unlicensed bands may be based on a CA configuration in conjunction with CCs operating in a licensed band. Operations in unlicensed spectrum may include downlink transmissions, uplink transmissions, or both. Duplexing in unlicensed spectrum may be based on frequency division duplexing (FDD), time division duplexing (TDD) or a combination of both.

<FIG> illustrates an example of a wireless communications system <NUM> that supports communication schemes for SCDD reference signals in accordance with various aspects of the present disclosure. In some examples, wireless communications system <NUM> may implement aspects of wireless communications system <NUM>. The wireless communications system <NUM> may include a UE <NUM>-a and a base station <NUM>-a, which may be examples of the UE <NUM> and base station <NUM> described with reference to <FIG>. Base station <NUM>-a may transmit one or more signals through one or more virtual antennas to UE <NUM>-a within geographic coverage area <NUM>-a. In some cases, wireless communications system <NUM> may deploy MIMO technology.

In some cases, because of the lossy channels in wireless communication systems, base station <NUM>-a may employ SCDD to optimize path loss and enable wideband channel estimation to accurately estimate channel quality. Path loss may be introduced due to communication with a high mobility UE <NUM>-a. The SCDD introduces a time offset, τ, between a first signal transmitted by a first virtual antenna (antenna <NUM>) and a second signal transmitted by a second virtual antenna (antenna <NUM>). In some cases, signals transmitted through the one or more virtual antennas may follow different paths <NUM> (e.g., path <NUM>-a, and path <NUM>-b) and the time offset introduced by SCDD may result in phase offset in frequency tones. According to some aspects, the phase change in a tone 'k' may be based at least in part on: the tone 'k', τ, and the subcarrier spacing (Δf). For example, the phase change in tone 'k' may be:
kΔθ, where: <MAT>.

The transmitted signal in tone k may be denoted by: <MAT>
where: <MAT>.

In a first scheme, the SCDD deployed may be based on Pre-coding Matrix Indicator (PMI) feedback. In such a scheme, the transmission scheme may be designed as described below. It should be noted, however, that other implementations of the transmission scheme may be considered without departing from the scope of the present disclosure.

In some cases, the layer (e.g., upper layers such as MAC, Network, Transport, etc.) to virtual antenna mapping matrix (denoted by U) may be formed by an initial phase 'θini'. Further, the final phase applied in each tone may be jointly determined by D(k) and U. As previously described, the matrix D(k) may comprise an indication of the phase offset for the second virtual antenna (antenna <NUM>) as compared to the first virtual antenna (antenna <NUM>). In some cases, U or θini may be determined based on UE subband feedback. For example, for dual-stage codebook, there may be <NUM> phase value candidates indicated by the UE subband feedback, by i2 as follows: <MAT>.

In some other cases, the phase value may have <NUM> candidates. These in turn may be denoted by: <MAT>, where n = <NUM>, <NUM>, <NUM>,. In some cases, 'U' may be determined based on channel reciprocity and D(k) may be determined based at least in part on UE feedback, which may include a CSI resource (CRI) or a quantization of the time offset τ (e.g., <NUM>, <NUM>, <NUM>, <NUM> microseconds). Further, in some instances, the base station <NUM>-a may be configured to determine or select D(k) and U (e.g., based on an indication from an upper layer node or from UE feedback).

In some cases, the base station <NUM>-a may determine a classification (e.g., class A, class B, hybrid, etc.) for transmission of one or more CSI-RS as well as a set of resources to be used for transmission of the CSI-RS. In some examples, the classification may be used to determine the set of resources for transmission of the CSI-RS (e.g., to the UE <NUM>-a). The base station <NUM>-a may also determine one or more precoders, which may differ between antenna ports of the base station.

In some examples, the base station <NUM>-a may determine a feedback type for the UE <NUM>-a, which may include and a list of parameters for the UE <NUM>-a to consider when providing feedback. For instance, the base station <NUM>-a (or other network node) may configure the UE <NUM>-a to provide feedback for one or more of: CRI, Rank Indicator (RI), PMI, CQI, etc. In some cases, the base station <NUM>-a may determine the time offset configuration applied during SCDD, as well as a closed-loop or semi open-loop switching mode. The closed-loop mode may request that the UE <NUM>-a explicitly provide feedback information about the channel in order to assist the base station <NUM>-a in choosing a transmission scheme for the multiple antennas. In other cases, an open or semi-open loop mode may not involve an explicit channel feedback from the UE <NUM>-a.

In some examples, the base station <NUM>-a may indicate information pertaining to the CSI-RS class and resources, feedback type and content, timing offset configuration applied in SCDD, closed or semi-open loop switching mode, or any other CSI-RS configuration related information to the UE <NUM>-a dynamically (e.g., via Downlink Control Information (DCI)) or semi-statically (e.g., via Radio Resource Configuration (RRC)). In some cases, the base station <NUM>-a may modify the DCI by embedding the time offset in a DCI format for CSI-RS or may use a DCI format designed to indicate the time offset.

Following determination of a CSI-RS configuration, the base station <NUM>-a may then proceed to transmit the CSI-RS signals according to the configuration. In some cases, the UE <NUM>-a may receive the one or more CSI-RS signals and may subsequently proceed to measure the channel. Based on the measurement and the time offset, the UE <NUM>-a may derive one or more CSI parameters and may determine the selected time offset (e.g., zero or non-zero) for SCDD.

According to various aspects, the time offset indication for CSI derivation may be network configured, UE configured, or a combination. In some cases, the time offset indication for CSI derivation may be configured by the base station <NUM>-a with class A CSI-RS. In some examples, for a Class A CSI reporting class, the UE <NUM>-a may report CSI according to a codebook based on CSI-RS ports. For instance, the codebook may be known to the UE <NUM>-a or the UE <NUM>-a may be informed of which codebook to use (e.g., via signaling such as RRC signaling). In some instances, for CSI reporting class A, each of the one or more antenna elements of the base station <NUM>-a may transmit a unique CSI-RS per polarization. Also for class A CSI reporting, the base station <NUM>-a may configure the time offset based on a channel property, such as delay spread. The delay spread may arise due to the multipath nature of a communication channel. For example, there may be an arrival time difference between the line-of-sight (LOS) component of a channel arriving at the UE <NUM>-a, and the multipath component (e.g., after reflecting off buildings) of the channel. In some cases, the base station <NUM>-a may indicate to the UE <NUM>-a the time offset together with the CSI-RS configuration signaling. As previously described, the base station <NUM>-a may provide an indication of the information pertaining to the CSI-RS class and resources, and timing offset configuration dynamically (e.g., via DCI) or semi-statistically (e.g., via RRC). Following receiving an indication of the timing offset and the CSI-RS configuration signaling from the base station <NUM>-a, the UE <NUM>-a may proceed to compute one or more of: RI, PMI, CQI, etc. In some cases, a timing offset (or τ)=<NUM> may imply a CSI derivation for a closed-loop transmission scheme.

In another example of network configured time offset indication for CSI, the time offset indication for CSI derivation may be configured by the network with K=<NUM> Class B or hybrid CSI-RS. In some examples, for a class B or hybrid CSI reporting class, the UE <NUM>-a may report on multiple beam-formed CSI reference signals. In some cases, one or more CSI-RS resources may be configured in the UE <NUM>-a, where each CSI-RS resource may consist of one or more antenna ports per beam. In some examples of a network configured time offset for class B or hybrid CSI reporting, the base station <NUM>-a may configure a CSI-RS resource (K = <NUM>), and a time offset. Further, in such cases, the precoder of CSI-RS may be formed by a beam and the configured delay offset. Following receiving the CSI-RS from the base station <NUM>-a, the UE <NUM>-a may proceed to compute and report RI, PMI, and CQI. In some cases, the UE <NUM>-a may not need to know the value of the delay offset, by τ virtue of the CSI-RS precoder being formed by a beam and the delay offset. In some cases, a timing offset (or τ)=<NUM> may imply a CSI derivation for a closed-loop transmission scheme.

In another example of time offset indication for CSI, a fixed time offset may be used with class A CSI-RS reporting. For example, a fixed time offset known to both the UE <NUM>-a and the network or base station <NUM>-a, or explicitly specified in the specification may be employed for deriving RI, PMI, and CQI.

In an example of UE selected or configured time offset indication with class A CSI-RS reporting, UE <NUM>-a may select an optimum time offset from a set of timing offset candidates. For example, the candidates (e.g., <NUM>, <NUM>, <NUM>, <NUM>, etc.) may be fixed and explicitly specified to the UE <NUM>-a. Further, in some cases, the UE <NUM>-a may merely select from a set of candidates dynamically (DCI) or semi-statistically (RRC) configured by the network. Following receiving the CSI-RS from the network, the UE <NUM>-a may proceed to derive the RI, PMI, and CQI, which may be dependent on the time offset previously chosen. The UE <NUM>-a may then report the RI, PMI, and CQI to the base station <NUM>-a. In some cases, a timing offset (or τ)=<NUM> may imply a CSI derivation for a closed-loop transmission scheme.

In another example of UE selected or configured time offset indication, the UE <NUM>-a may utilize class B or hybrid CSI-RS reporting. In some cases, the network may configure two or more CSI-RS resources (K > <NUM>) for CSI reporting. In such cases, the precoder of CSI-RS in each resource may be formed by a beam and a chosen delay offset from a set of candidates (e.g., <NUM>, <NUM>, <NUM>, <NUM>, etc.) In some cases, each of the CSI-RS resources may be denoted or identified by a CSI-RS resource index (CRI). In some cases, the UE <NUM>-a may report CRI, RI, PMI, and CQI associated with the CRI following receiving the CSI-RS from the network. In some cases, a timing offset (or τ)=<NUM> may imply a CSI derivation for a closed-loop transmission scheme.

In some cases, the UE <NUM>-a may employ inner PMI (i.e., i2) as the initial phase when deriving CQI. In such cases, the reported i2 may be based at least in part on, or dependent on the time offset selected. Further, a zero time offset may imply a CSI report for a closed-loop transmission mode. In some cases, the reported i2 may be wideband, partial band, or subband specific.

<FIG> illustrates an example of a process flow <NUM> that supports communication schemes for SCDD reference signals in accordance with various aspects of the present disclosure. In some examples, process flow <NUM> may implement aspects of wireless communications systems <NUM> or <NUM>, as described with reference to <FIG> and <FIG>. UE <NUM>-b and base station <NUM>-b may be examples of the corresponding devices described above with reference to <FIG> and <FIG>. Process flow <NUM> may be an example of a network configured time offset indication for CSI using non-precoded CSI-RS (e.g., Class A CSI-RS).

At <NUM>, the UE <NUM>-b may receive a control message from base station <NUM>-b. In some cases, the control message may comprise a DCI or RRC message. In some examples, the DCI or RRC message may include at least one CSI configuration parameter.

At <NUM>, the UE <NUM>-b may identify a time offset between two or more virtual antennas of the base station. In some cases, the time offset may be identified based at least in part on the at least one CSI configuration parameter (e.g., as indicated by or included in the control message).

At <NUM>, the UE <NUM>-b may receive a first non-precoded CSI-RS of a plurality of CSI-RSs over a first set of resources associated with a first CSI configuration parameter. In some cases, the UE <NUM>-b may also receive a second non-precoded CSI-RS of the plurality of CSI-RSs over a second set of resources associated with a second CSI configuration parameter. The first and second non-precoded CSI-RSs may be transmitted by the base station <NUM>-b according to the at least one CSI configuration parameter.

At <NUM>, the UE <NUM>-b may perform CSI-RS measurements on at least one CSI-RS (e.g., the first CSI-RS, the second CSI-RS) of the plurality of CSI-RSs. In some examples, the UE <NUM>-b may perform measurements on each of the plurality of CSI-RSs.

At <NUM>, the UE <NUM>-b may determine the at least one CSI parameter such as RI, PMI, CQI, etc. In some cases, the UE <NUM>-b may determine RI, PMI, and/or CQI based on the time offset determined at <NUM>. Further, in some examples, the at least one CSI parameter may be based at least in part on the first non-precoded CSI-RS or the second non-precoded CSI-RS received from the base station <NUM>-b (e.g., as received in <NUM>).

At <NUM>, the UE <NUM>-b may transmit a feedback message to the base station <NUM>-b. The feedback message may be based at least in part on the time offset (e.g., as identified at <NUM>) or the CSI-RS measurements (e.g. as performed at <NUM>). In some cases, the UE <NUM>-b may select a closed loop transmission scheme procedure for transmitting the feedback message to the base station <NUM>-b (e.g., based on a determination that the time offset equals <NUM>). Further, in some examples, the feedback message may include the at least one CSI parameter, such as RI, PMI, CQI, etc., as determined in <NUM>.

<FIG> illustrates an example of a process flow <NUM> that supports communication schemes for SCDD reference signals in accordance with various aspects of the present disclosure. In some examples, process flow <NUM> may implement aspects of wireless communications systems <NUM> or <NUM> as described with reference to <FIG> and <FIG>. UE <NUM>-c and base station <NUM>-c may be examples of the corresponding devices described above with reference to <FIG> and <FIG>. Process flow <NUM> may be an example of a network configured time offset indication for CSI using precoded CSI-RS (e.g., Class B CSI-RS).

At <NUM>, the UE <NUM>-c may receive a control message from base station <NUM>-c. In some cases, the control message may comprise a DCI or RRC message. In some examples, the DCI or RRC message may include at least one CSI configuration parameter.

At <NUM>, the UE <NUM>-c may identify a CSI-RS configuration. The CSI-RS may be identified based at least in part on the control message and in some cases may be determined based at least in part on the at least one CSI configuration parameter. In some examples, a network entity (e.g., a core network node or base station <NUM>-c) may configure precoded CSI-RS resources for CSI-RS reporting.

At <NUM>, the UE <NUM>-c may receive one or more precoded CSI-RSs from the base station <NUM>-c. In such cases, the precoder for CSI-RS of each resource may be formed by a beam and a delay offset selected from a set of candidates (e.g., <NUM>, <NUM>, <NUM>, <NUM>).

At <NUM>, the UE <NUM>-c may estimate an effective channel. In some cases, the UE <NUM>-c may perform CSI-RS measurements on one or more CSI-RSs transmitted by the base station <NUM>-c, which may be used to estimate the effective channel.

At <NUM>, the UE <NUM>-c may determine at least one CSI parameter (e.g., RI, PMI, CRI, CQI). In some examples, the at least one CSI parameter may be determined based at least in part on the effective channel (e.g., as estimated at <NUM>).

At <NUM>, the UE <NUM>-c may transmit a feedback message to the base station <NUM>-c, which may be based at least in part on the CSI-RS measurements. In some cases, the reported CSI parameter may correspond to a closed loop transmission scheme (e.g., if the base station <NUM>-c precodes the CSI-RS based a time offset that equals <NUM>). In some examples, the feedback message may include the at least one CSI parameter, such as RI, PMI, CRI, CQI, etc..

<FIG> illustrates an example of a process flow <NUM> that supports communication schemes for SCDD reference signals in accordance with various aspects of the present disclosure. In some examples, process flow <NUM> may implement aspects of wireless communications systems <NUM> or <NUM> as described with reference to <FIG> and <FIG>. UE <NUM>-d and base station <NUM>-d may be examples of the corresponding devices described above with reference to <FIG> and <FIG>. Process flow <NUM> may be an example of a network configured time offset indication for CSI, where a fixed time offset may be used for CSI reporting.

At <NUM>, the UE <NUM>-d may receive a control message from base station <NUM>-d. In some cases, the control message may comprise a DCI or RRC message. In some examples, the DCI or RRC message may include at least one CSI configuration parameter.

At <NUM>, the UE <NUM>-d may identify a CSI-RS configuration. The CSI-RS may be identified based at least in part on the control message (e.g., the CSI-RS configuration may be indicated by or included in the control message). In some cases, the CSI-RS may be identified based at least in part on the at least one CSI configuration parameter. In some examples, a network entity (e.g., a core network node or base station <NUM>-d) may configure precoded or non-precoded CSI-RS resources for CSI-RS reporting.

At <NUM>, the UE <NUM>-d may receive one or more CSI-RSs, which may be transmitted by base station <NUM>-d. The one or more CSI-RSs may include precoded or non-precoded CSI-RSs, which may be received over corresponding sets of resources (e.g., as configured by a core network node or base station <NUM>-d. In some examples, the one or more CSI-RSs may be transmitted by the base station <NUM>-b according to the at least one CSI configuration parameter.

At <NUM>, the UE <NUM>-d may perform CSI-RS measurements on the at least one CSI-RSs received at <NUM>. In some cases, a fixed time offset known to both the UE <NUM>-d and the network or base station <NUM>-d may be used for performing CSI-RS measurements.

At <NUM>, the UE <NUM>-d may determine at least one CSI parameter (e.g., RI, PMI, CRI, CQI). The at least one CSI parameter may be determined based on the CSI-RS measurements (e.g., as performed at <NUM>).

At <NUM>, the UE <NUM>-d may transmit a feedback message to the base station <NUM>-d. The feedback message may be reported to the base station <NUM>-d and may be based at least in part on the CSI-RS measurements. In some examples, the feedback message may include at least one CSI parameter, such as RI, CRI PMI, CQI, etc., as determined at <NUM>.

<FIG> illustrates an example of a process flow <NUM> that supports communication schemes for SCDD reference signals in accordance with various aspects of the present disclosure. In some examples, process flow <NUM> may implement aspects of wireless communications systems <NUM> or <NUM> as described with reference to <FIG> and <FIG>. UE <NUM>-e and base station <NUM>-e may be examples of the corresponding devices described above with reference to <FIG> and <FIG>. Process flow <NUM> may be an example of a network assisted UE determined time offset for CSI derivation using non-precoded CSI-RS.

At <NUM>, the UE <NUM>-e may receive a control message from base station <NUM>-e. In some cases, the control message may comprise a DCI or RRC message. In some examples, the DCI or RRC message may include at least one CSI configuration parameter.

At <NUM>, the UE <NUM>-e may obtain a set of time offset candidates. The set of time offset candidates may be indicated by the control message (e.g., based on the at least one CSI configuration parameter), as received at <NUM>. In some cases, the set of time offset candidates may be dynamically configured by the network or base station <NUM>-e (e.g., via DCI). In some examples, the time offset candidates may be semi-statistically (RRC) configured by the network or base station <NUM>-e (e.g., via RRC).

At <NUM>, the UE <NUM>-e may receive one or more non-precoded CSI-RSs over a set of resources, which may be associated with a CSI configuration parameter. The one or more CSI-RSs may be transmitted by the base station <NUM>-e.

At <NUM>, the UE <NUM>-e may perform CSI-RS measurements on the at least one CSI-RS (e.g., as received from the base station <NUM>-e at <NUM>).

At <NUM>, the UE <NUM>-e may select a time offset from the set of time offset candidates obtained at <NUM>. The UE <NUM>-e may select a time offset by trying each time offset candidate (e.g., as obtained at <NUM>) and determining the spectral efficiency for each time offset candidate. In some cases, the time offset associated with the highest spectral efficiency may be selected.

At <NUM>, the UE <NUM>-e may determine, based on the time offset selected at <NUM>, at least one CSI parameter (e.g., RI, PMI, and/or CQI). In some examples, the at least one CSI parameter may be determined based on an association between the time offset (e.g., selected at <NUM>) and a set of CSI parameters.

At <NUM>, the UE <NUM>-e may transmit a feedback message to the base station <NUM>-e, which may be based at least in part on the time offset (e.g., as selected at <NUM>) and the CSI-RS measurements (e.g., as determined at <NUM>). In some cases, the UE <NUM>-e may select a closed loop transmission scheme procedure for transmitting the feedback message to the base station <NUM>-e (e.g., based on a time offset of <NUM>). In some examples, the UE <NUM>-e may report the at least one CSI parameter (e.g., RI, PMI, CQI) to the base station <NUM>-e in the feedback message.

<FIG> illustrates an example of a process flow <NUM> that supports communication schemes for SCDD reference signals in accordance with various aspects of the present disclosure. In some examples, process flow <NUM> may implement aspects of wireless communications systems <NUM> or <NUM> as described with reference to <FIG> and <FIG>. UE <NUM>-f and base station <NUM>-f may be examples of the corresponding devices described above with reference to <FIG> and <FIG>. Process flow <NUM> may be an example of a network assisted UE determined time offset for CSI derivation using precoded CSI-RS.

At <NUM>, the UE <NUM>-f may receive a control message from base station <NUM>-f. In some cases, the control message may comprise a DCI or RRC message. In some examples, the DCI or RRC message may include at least one CSI configuration parameter.

At <NUM>, the UE <NUM>-f may identify a CSI-RS configuration. The CSI-RS may be identified based at least in part on the control message and in some cases may be determined based at least in part on the at least one CSI configuration parameter.

At <NUM>, the UE <NUM>-f may receive one or more precoded CSI-RSs over a set of resources associated with a CSI configuration parameter. For instance, different precoders of base station <NUM>-f may be associated with different sets of resources. The one or more CSI-RSs may be transmitted by the base station <NUM>-f. In some cases, the base station <NUM>-f may configure two or more CSI-RS resources for CSI reporting. In such cases, the precoder for CSI-RS in each resource may be formed by a beam and a specific time offset selected from a set of candidates (e.g., <NUM>, <NUM>, <NUM>, <NUM>).

At <NUM>, the UE <NUM>-f estimate an effective channel. In some cases, the UE <NUM>-f may perform CSI-RS measurements on one or more CSI-RSs transmitted by the base station <NUM>-f, which may be used to estimate the effective channel. The UE <NUM>-f may select a CSI-RS resource of the one or more precoded CSI-RS resources based on the measurements and compute one or more CSI parameters (e.g., CRI, RI, PMI, CQI) based at least in part on the selected CSI-RS. In some examples, the one or more CSI parameters may be computed based at least in part on the estimated effective channel. In some aspects, at least one CSI parameter may be based at least in part on the one or more precoded CSI-RSs received from the base station <NUM>-f at <NUM>.

At <NUM>, the UE <NUM>-f may transmit a feedback message containing the CSI parameters to the base station <NUM>-f, which may be based at least in part on the selected CSI-RS resource and the channel measurements. In some cases, if the CSI-RS of the selected CSI-RS resource is precoded based on a time offset equal to <NUM>, the reported CSI parameters may be determined to be for a closed loop transmission scheme. In some examples, the UE <NUM>-f may report CRI, RI, PMI, and CQI associated with the CRI following reception of the at least one CSI-RS from the base station <NUM>-f.

<FIG> shows a block diagram <NUM> of a wireless device <NUM> that supports communication schemes for SCDD reference signals in accordance with aspects of the present disclosure. Wireless device <NUM> may be an example of aspects of a UE <NUM> as described herein. Wireless device <NUM> may include receiver <NUM>, UE communications manager <NUM>, and transmitter <NUM>. Wireless device <NUM> may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses).

Receiver <NUM> may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to communication schemes for SCDD reference signals, etc.). Information may be passed on to other components of the device. The receiver <NUM> may be an example of aspects of the transceiver <NUM> described with reference to <FIG>. The receiver <NUM> may utilize a single antenna or a set of antennas.

UE communications manager <NUM> may be an example of aspects of the UE communications manager <NUM> described with reference to <FIG>.

UE communications manager <NUM> and/or at least some of its various sub-components may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions of the UE communications manager <NUM> and/or at least some of its various sub-components may be executed by a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), an 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 in the present disclosure.

The UE communications manager <NUM> and/or at least some of its various sub-components may be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations by one or more physical devices. In some examples, UE communications manager <NUM> and/or at least some of its various sub-components may be a separate and distinct component in accordance with various aspects of the present disclosure. In other examples, UE communications manager <NUM> and/or at least some of its various sub-components may be combined with one or more other hardware components, including but not limited to an I/O component, a transceiver, a network server, another computing device, one or more other components described in the present disclosure, or a combination thereof in accordance with various aspects of the present disclosure.

UE communications manager <NUM> may receive, from a base station, a control message including at least one CSI configuration parameter and identify a time offset between a set of virtual antennas of the base station based on the at least one CSI configuration parameter. UE communications manager <NUM> perform measurements of a set of CSI-RSs associated with the set of virtual antennas of the base station and transmit, to the base station, a feedback message based on the identified time offset and the measurements of the set of CSI-RSs. The UE communications manager <NUM> may also receive a first CSI-RS of a set of CSI-RSs over a first set of resources corresponding to a first beam and a first delay offset, determine a first CSI parameter based on the first CSI-RS, and transmit, to the base station, a feedback message based on the determined first CSI parameter.

<FIG> shows a block diagram <NUM> of a wireless device <NUM> that supports communication schemes for SCDD reference signals in accordance with aspects of the present disclosure. Wireless device <NUM> may be an example of aspects of a wireless device <NUM> or a UE <NUM> as described with reference to <FIG>. Wireless device <NUM> may include receiver <NUM>, UE communications manager <NUM>, and transmitter <NUM>. Wireless device <NUM> may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses).

UE communications manager <NUM> may be an example of aspects of the UE communications manager <NUM> described with reference to <FIG>. UE communications manager <NUM> may also include reception component <NUM>, time offset component <NUM>, measurement component <NUM>, transmission component <NUM>, CSI-RS receiver <NUM>, CSI parameter component <NUM>, and feedback transmitter <NUM>.

Reception component <NUM> may receive, from a base station, a control message including at least one CSI configuration parameter. In some cases, the control message includes DCI from the base station, the DCI including the at least one CSI configuration parameter. In some cases, a format of the DCI includes at least one of a special DCI format or a DCI format for CSI-RS. In some cases, the DCI is for the UE or a group of UEs including the UE. In some cases, the control message includes an RRC message including the at least one CSI configuration parameter.

Time offset component <NUM> may identify a time offset between a set of virtual antennas of the base station based on the at least one CSI configuration parameter. In some cases, identifying the time offset includes: calculating the time offset based on the at least one CSI configuration parameter. In some cases, identifying the time offset includes: receiving an indication of a time offset configuration from the base station, the time offset configuration determined by one of a core network node or the base station. In some cases, the indication is received via DCI or a RRC message. In some cases, determining the time offset includes: selecting the time offset from a set of time offset candidates based on the measurements of the set of CSI-RSs. In some cases, the time offset candidates are determined based on the control message.

Measurement component <NUM> may perform, by the UE, measurements of a set of CSI-RSs associated with the set of virtual antennas of the base station and determine a fixed value of the time offset for use in performing the measurements, where the feedback message is based on the fixed value of the time offset.

Transmission component <NUM> may transmit, to the base station, a feedback message based on the identified time offset and the measurements of the set of CSI-RSs. In some cases, transmitting the feedback message further includes: transmitting an initial co-phase vector between the set of virtual antennas of the base station.

CSI-RS receiver <NUM> may receive a first CSI-RS of a set of CSI-RSs over a first set of resources corresponding to a first beam and a first delay offset and receive a second CSI-RS of the set of CSI-RSs over a second set of resources corresponding to a second beam and a second delay offset.

CSI parameter component <NUM> may determine a first CSI parameter based on the first CSI-RS and determine a second CSI parameter based on the second CSI-RS.

Feedback transmitter <NUM> may transmit, to the base station, a feedback message based on the determined first CSI parameter and transmit, to the base station, the feedback message based on the determined the second CSI parameter. In some cases, the feedback message includes at least one of a CRI, an RI, a PMI, an initial co-phase indicator, a CQI, or a combination thereof.

<FIG> shows a block diagram <NUM> of a UE communications manager <NUM> that supports communication schemes for SCDD reference signals in accordance with aspects of the present disclosure. The UE communications manager <NUM> may be an example of aspects of a UE communications manager <NUM>, a UE communications manager <NUM>, or a UE communications manager <NUM> described with reference to <FIG>, <FIG>, and <FIG>. The UE communications manager <NUM> may include reception component <NUM>, time offset component <NUM>, measurement component <NUM>, transmission component <NUM>, CSI-RS receiver <NUM>, CSI parameter component <NUM>, feedback transmitter <NUM>, feedback component <NUM>, and scheme component <NUM>. Each of these modules may communicate, directly or indirectly, with one another (e.g., via one or more buses).

Reception component <NUM> may receive, from a base station, a control message including at least one CSI configuration parameter. In some cases, the control message includes DCI from the base station, the DCI including the at least one CSI configuration parameter. In some cases, a format of the DCI includes at least one of a special DCI format or a DCI format for CSI-RS. In some cases, the DCI is for the UE or a group of UEs including the UE. In some cases, the control message includes a RRC message including the at least one CSI configuration parameter.

Time offset component <NUM> may identify, by a UE, a time offset between a set of virtual antennas of the base station based on the at least one CSI configuration parameter. In some cases, identifying the time offset includes: calculating the time offset based on the at least one CSI configuration parameter. In some cases, identifying the time offset includes: receiving an indication of a time offset configuration from the base station, the time offset configuration determined by one of a core network node or the base station. In some cases, the indication is received via DCI or a RRC message. In some cases, determining the time offset includes: selecting the time offset from a set of time offset candidates based on the measurements of the set of CSI-RSs. In some cases, the time offset candidates are determined based on the control message.

Feedback component <NUM> may compute CSI feedback for at least one CSI-RS based on the time offset configuration, where the feedback message includes the computed CSI feedback and determine, based on the time offset, at least one CSI parameter from a group consisting of: a rank indicator, an initial co-phase indicator, a precoder matrix indicator, and a channel quality indicator, where the determined at least one CSI parameter is included in the feedback message.

Scheme component <NUM> may select, based on a determination that the time offset equals <NUM> or a determination that a selected CSI resource corresponds to the time offset equal to <NUM>, a closed loop transmission scheme procedure for transmitting the feedback message and select a closed loop transmission scheme procedure for transmitting the feedback message.

<FIG> shows a diagram of a system <NUM> including a device <NUM> that supports communication schemes for SCDD reference signals in accordance with aspects of the present disclosure. Device <NUM> may be an example of or include the components of wireless device <NUM>, wireless device <NUM>, or a UE <NUM> as described above, e.g., with reference to <FIG> and <FIG>. Device <NUM> may include components for bi-directional voice and data communications including components for transmitting and receiving communications, including UE communications manager <NUM>, processor <NUM>, memory <NUM>, software <NUM>, transceiver <NUM>, antenna <NUM>, and I/O controller <NUM>. These components may be in electronic communication via one or more buses (e.g., bus <NUM>). Device <NUM> may communicate wirelessly with one or more base stations <NUM>.

Processor <NUM> may include an intelligent hardware device, (e.g., a general-purpose processor, a DSP, a central processing unit (CPU), a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof). In some cases, processor <NUM> may be configured to operate a memory array using a memory controller. In other cases, a memory controller may be integrated into processor <NUM>. Processor <NUM> may be configured to execute computer-readable instructions stored in a memory to perform various functions (e.g., functions or tasks supporting communication schemes for SCDD reference signals).

Software <NUM> may include code to implement aspects of the present disclosure, including code to support communication schemes for SCDD reference signals. Software <NUM> may be stored in a non-transitory computer-readable medium such as system memory or other memory. In some cases, the software <NUM> may not be directly executable by the processor but may cause a computer (e.g., when compiled and executed) to perform functions described herein.

In some cases, a user may interact with device <NUM> via <NUM>/O controller <NUM> or via hardware components controlled by I/O controller <NUM>.

<FIG> shows a block diagram <NUM> of a wireless device <NUM> that supports communication schemes for SCDD reference signals in accordance with aspects of the present disclosure. Wireless device <NUM> may be an example of aspects of a base station <NUM> as described herein. Wireless device <NUM> may include receiver <NUM>, base station communications manager <NUM>, and transmitter <NUM>. Wireless device <NUM> may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses).

Base station communications manager <NUM> may be an example of aspects of the base station communications manager <NUM> described with reference to <FIG>. Base station communications manager <NUM> and/or at least some of its various sub-components may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions of the base station communications manager <NUM> and/or at least some of its various sub-components may be executed by a general-purpose processor, a DSP, an ASIC, an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described in the present disclosure.

The base station communications manager <NUM> and/or at least some of its various sub-components may be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations by one or more physical devices. In some examples, base station communications manager <NUM> and/or at least some of its various sub-components may be a separate and distinct component in accordance with various aspects of the present disclosure. In other examples, base station communications manager <NUM> and/or at least some of its various sub-components may be combined with one or more other hardware components, including but not limited to an I/O component, a transceiver, a network server, another computing device, one or more other components described in the present disclosure, or a combination thereof in accordance with various aspects of the present disclosure.

Base station communications manager <NUM> may transmit a control message including at least one CSI configuration parameter and a request to report a time offset between a set of virtual antennas of the base station and measurements of a set of CSI-RSs associated with the set of virtual antennas of the base station and receive, from a UE and in response to the request, a feedback message based on the time offset and the measurements of the set of CSI-RSs. The base station communications manager <NUM> may also transmit, to a UE, a first CSI-RS of a set of CSI-RSs over a first set of resources corresponding to a first beam and a first delay offset and receive, from the UE, a feedback message that includes a first CSI parameter, where the first CSI parameter is based on the first CSI-RS.

<FIG> shows a block diagram <NUM> of a wireless device <NUM> that supports communication schemes for SCDD reference signals in accordance with aspects of the present disclosure. Wireless device <NUM> may be an example of aspects of a wireless device <NUM> or a base station <NUM> as described with reference to <FIG>. Wireless device <NUM> may include receiver <NUM>, base station communications manager <NUM>, and transmitter <NUM>. Wireless device <NUM> may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses).

Base station communications manager <NUM> may be an example of aspects of the base station communications manager <NUM> described with reference to <FIG>. Base station communications manager <NUM> may also include control component <NUM>, feedback receiver <NUM>, CSI-RS transmitter <NUM>, and CSI parameter receiver <NUM>.

Control component <NUM> may transmit a control message including at least one CSI configuration parameter and a request to report a time offset between a set of virtual antennas of the base station and measurements of a set of CSI-RSs associated with the set of virtual antennas of the base station.

Feedback receiver <NUM> may receive, from a UE and in response to the request, a feedback message based on the time offset and the measurements of the set of CSI-RSs, receive, from the UE, a UE time offset and at least one CSI parameter based on the UE time offset, where the at least one CSI parameter is included in the feedback message, and receive, from the UE, at least one CSI parameter based on a fixed time offset where the at least one CSI parameter is included in the feedback message. In some cases, the feedback message includes CSI feedback for at least one CSI-RS of the set of CSI-RSs based on the time offset configuration.

CSI-RS transmitter <NUM> may transmit, to a UE, a first CSI-RS of a set of CSI-RSs over a first set of resources corresponding to a first beam and a first delay offset and transmit, to the UE, a second CSI-RS of the set of CSI-RSs over a second set of resources corresponding to a second beam and a second delay offset, where the feedback message includes a second CSI parameter based on the second CSI-RS.

CSI parameter receiver <NUM> may receive, from the UE, a feedback message that includes a first CSI parameter, where the first CSI parameter is based on the first CSI-RS.

<FIG> shows a block diagram <NUM> of a base station communications manager <NUM> that supports communication schemes for SCDD reference signals in accordance with aspects of the present disclosure. The base station communications manager <NUM> may be an example of aspects of a base station communications manager <NUM> described with reference to <FIG>, <FIG>, and <FIG>. The base station communications manager <NUM> may include control.

component <NUM>, feedback receiver <NUM>, CSI-RS transmitter <NUM>, CSI parameter receiver <NUM>, indication component <NUM>, and configuration component <NUM>. Each of these modules may communicate, directly or indirectly, with one another (e.g., via one or more buses).

Feedback receiver <NUM> may receive, from a UE and in response to the request, a feedback message based on the time offset and the measurements of the set of CSI-RSs, receive, from the UE, a UE time offset and at least one CSI parameter based on the UE time offset, where the at least one CSI parameter is included in the feedback message, and receive, from the UE, at least one CSI parameter based on a fixed time offset, where the at least one CSI parameter is included in the feedback message. In some cases, the feedback message includes CSI feedback for at least one CSI-RS of the set of CSI-RSs based on the time offset configuration.

Indication component <NUM> may transmit, to the UE, an indication of a time offset configuration, the time offset configuration determined by one of a core network node or the base station. In some cases, the indication is transmitted via DCI, a radio resource control message, or within the control message.

Configuration component <NUM> may configure a set of time offset candidates for the UE, where the control message includes the set of time offset candidates.

<FIG> shows a diagram of a system <NUM> including a device <NUM> that supports communication schemes for SCDD reference signals in accordance with aspects of the present disclosure. Device <NUM> may be an example of or include the components of base station <NUM> as described above, e.g., with reference to <FIG>. Device <NUM> may include components for bi-directional voice and data communications including components for transmitting and receiving communications, including base station communications manager <NUM>, processor <NUM>, memory <NUM>, software <NUM>, transceiver <NUM>, antenna <NUM>, network communications manager <NUM>, and inter-station communications manager <NUM>. These components may be in electronic communication via one or more buses (e.g., bus <NUM>). Device <NUM> may communicate wirelessly with one or more UEs <NUM>.

Processor <NUM> may include an intelligent hardware device, (e.g., a general-purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof). In some cases, processor <NUM> may be configured to operate a memory array using a memory controller. In other cases, a memory controller may be integrated into processor <NUM>. Processor <NUM> may be configured to execute computer-readable instructions stored in a memory to perform various functions (e.g., functions or tasks supporting communication schemes for SCDD reference signals).

Inter-station communications manager <NUM> may manage communications with other base station <NUM>, and may include a controller or scheduler for controlling communications with UEs <NUM> in cooperation with other base stations <NUM>. In some examples, inter-station communications manager <NUM> may provide an X2 interface within an LTE/LTE-A wireless communication network technology to provide communication between base stations <NUM>.

<FIG> shows a flowchart illustrating a method <NUM> for communication schemes for SCDD reference signals in accordance with aspects of the present disclosure. The operations of method <NUM> may be implemented by a UE <NUM> or its components as described herein. For example, the operations of method <NUM> may be performed by a UE communications manager as described with reference to <FIG>. In some examples, a UE <NUM> may execute a set of codes to control the functional elements of the device to perform the functions described below. Additionally or alternatively, the UE <NUM> may perform aspects of the functions described below using special-purpose hardware.

At block <NUM> the UE <NUM> may receive, from a base station, a control message comprising at least one CSI configuration parameter. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a reception component as described with reference to <FIG>.

At block <NUM> the UE <NUM> may identify a time offset between a plurality of virtual antennas of the base station based at least in part on the at least one CSI configuration parameter. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a time offset component as described with reference to <FIG>.

At block <NUM> the UE <NUM> may perform measurements of a plurality of CSI-RSs associated with the plurality of virtual antennas of the base station. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a measurement component as described with reference to <FIG>.

At block <NUM> the UE <NUM> may transmit, to the base station, a feedback message based at least in part on the identified time offset and the measurements of the plurality of CSI-RSs. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a transmission component as described with reference to <FIG>.

At block <NUM> the UE <NUM> may receive a first CSI-RS of a plurality of CSI-RSs over a first set of resources corresponding to a first beam and a first delay offset. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a CSI-RS receiver as described with reference to <FIG>.

At block <NUM> the UE <NUM> may determine a first CSI parameter based at least in part on the first CSI-RS. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a CSI parameter component as described with reference to <FIG>.

At block <NUM> the UE <NUM> may transmit, to the base station, a feedback message based at least in part on the determined first CSI parameter. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a feedback transmitter as described with reference to <FIG>.

<FIG> shows a flowchart illustrating a method <NUM> for communication schemes for SCDD reference signals in accordance with aspects of the present disclosure. The operations of method <NUM> may be implemented by a base station <NUM> or its components as described herein. For example, the operations of method <NUM> may be performed by a base station communications manager as described with reference to <FIG>. In some examples, a base station <NUM> may execute a set of codes to control the functional elements of the device to perform the functions described below. Additionally or alternatively, the base station <NUM> may perform aspects of the functions described below using special-purpose hardware.

At block <NUM> the base station <NUM> may transmit a control message comprising at least one CSI configuration parameter and a request to report a time offset between a plurality of virtual antennas of the base station and measurements of a plurality of CSI-RSs associated with the plurality of virtual antennas of the base station. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a control component as described with reference to <FIG>.

At block <NUM> the base station <NUM> may receive, from a UE and in response to the request, a feedback message based at least in part on the time offset and the measurements of the plurality of CSI-RSs. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a feedback receiver as described with reference to <FIG>.

At block <NUM> the base station <NUM> may transmit, to a UE, a first CSI-RS of a plurality of CSI-RSs over a first set of resources corresponding to a first beam and a first delay offset. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a CSI-RS transmitter as described with reference to <FIG>.

At block <NUM> the base station <NUM> may receive, from the UE, a feedback message that includes a first CSI parameter, wherein the first CSI parameter is based at least in part on the first CSI-RS. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a CSI parameter receiver as described with reference to <FIG>.

The terms "system" and "network" are often used interchangeably. A code division multiple access (CDMA) system may implement a radio technology such as CDMA2000, Universal Terrestrial Radio Access (UTRA), etc. CDMA2000 covers IS-<NUM>, IS-<NUM>, and IS-<NUM> standards.

In LTE/LTE-A networks, including such networks described herein, the term evolved node B (eNB) may be generally used to describe the base stations. The wireless communications system or systems described herein may include a heterogeneous LTE/LTE-A or NR network in which different types of eNBs provide coverage for various geographical regions. For example, each eNB, next generation NodeB (gNB), or base station may provide communication coverage for a macro cell, a small cell, or other types of cell. The term "cell" may be used to describe a base station, a carrier or component carrier associated with a base station, or a coverage area (e.g., sector, etc.) of a carrier or base station, depending on context.

Base stations may include or may be referred to by those skilled in the art as a base transceiver station, a radio base station, an access point, a radio transceiver, a NodeB, eNodeB (eNB), gNB, Home NodeB, a Home eNodeB, or some other suitable terminology. The geographic coverage area for a base station may be divided into sectors making up only a portion of the coverage area. The wireless communications system or systems described herein may include base stations of different types (e.g., macro or small cell base stations). The UEs described herein may be able to communicate with various types of base stations and network equipment including macro eNBs, small cell eNBs, gNBs, relay base stations, and the like. There may be overlapping geographic coverage areas for different technologies.

By way of example, and not limitation, non-transitory computer-readable media may comprise RAM, ROM, electrically erasable programmable read only memory (EEPROM), compact disk (CD) ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor.

Claim 1:
A method for wireless communication, comprising:
receiving (<NUM>), from a base station, a control message comprising at least one channel state information, CSI, configuration parameter;
identifying (<NUM>), by a user equipment, UE, a time offset between a plurality of virtual antennas of the base station based at least in part on the at least one CSI configuration parameter;
performing (<NUM>), by the UE, measurements of a plurality of CSI reference signals, CSI-RSs, associated with the plurality of virtual antennas of the base station; and
transmitting (<NUM>), to the base station, a feedback message based at least in part on the identified time offset and the measurements of the plurality of CSI-RSs.