BEAM SELECTION USING A WINDOW FOR PRECODING

Methods, systems, and devices for wireless communications are described. A user equipment (UE) may perform a digital simulation to determining a precoding matrix indicator (PMI) associated with a digital reception beam. A base station may send, to the UE, a reference signal, and the UE may generate digital sector beams spanning a set of oversampled digital reception beams. The digital sector beams may be generated based on the number of antennas of the UE and a Kaiser Window configuration. The UE may perform a coarse beam search procedure on the reference signal using the set of digital sector beams and select a digital sector beam for a refined beam search used to determine a PMI for reporting to the base station.

FIELD OF TECHNOLOGY

The following relates generally to wireless communications and more specifically to beam selection using a window for precoding.

BACKGROUND

A UE may communicate with a base station or other UEs using beamforming techniques. A UE may have multiple panels (e.g., antenna modules, antenna arrays) which are used to form a communication beam (e.g., a reception beam or transmission beam) to communicate with base stations or other UEs. As the number of antenna elements (e.g., in an antenna array) at a UE increase, selection of appropriate precoder information may become more difficult and computationally complex, which may result in increased latency and communication inefficiencies. Further, inaccurate selection of appropriate precoder information may lead to inaccurate feedback provided by the UE to a base station, resulting in unsuitable or subpar communication parameters being utilized by the UE or base station for subsequent communications.

SUMMARY

The described techniques relate to improved methods, systems, devices, and apparatuses that support beam selection using a window for precoding. Generally, the described techniques allow a user equipment (UE) to determine precoder information (e.g., select a precoding matrix indicator (PMI)) using digital reception beams generated by the UE. For example, a base station may transmit a reference signal to the UE, and after reception of the reference signal, the UE may generate or define an initial set of digital reception beams to determine a coarse direction for reception of the reference signal. During a coarse beam search, the UE may generate a set of digital sector beams for spatial sectorization. The digital sector beams may be generated based on the number of antennas of the UE and a Kaiser window configuration. The UE may perform an initial beam search (e.g., a coarse beam search procedure (e.g., beam estimation)) on the reference signal using the set of digital sector beams. The UE may measure the signal quality (e.g., signal strength, received power) of the reference signal for each of the set of digital sector beams and select a digital sector beam based on the measurements (e.g., the UE may select the digital sector beam having the highest measured signal strength).

The UE may perform a second (e.g., refined) beam search procedure using a set of oversampled digital reception beams that correspond to the selected digital sector beam. As part of the refined beam search procedure, the UE may measure signal quality of the received reference signal for each of the oversampled digital reception beams and select the oversampled digital reception beam based on the measurements (e.g., the UE may select the oversampled digital reception beam having the highest measured signal strength). After selecting the oversampled digital reception beam, the UE may determine a PMI associated with the selected oversampled digital reception beam and transmit the PMI the base station.

A method of wireless communications at a UE is described. The method may include receiving, from a base station, a reference signal over a set of resources configured for channel state information (CSI), generating a set of digital sector beams for a beam search procedure based on a number of antennas of the UE and a Kaiser window configuration, performing the beam search procedure on the received reference signal using the set of digital sector beams, and selecting a first digital sector beam from the set of digital sector beams based on a result of the beam search procedure.

An apparatus for wireless communications at a UE is described. The apparatus may include a processor, memory coupled with the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to receive, from a base station, a reference signal over a set of resources configured for CSI, generate a set of digital sector beams for a beam search procedure based on a number of antennas of the UE and a Kaiser window configuration, perform the beam search procedure on the received reference signal using the set of digital sector beams, and select a first digital sector beam from the set of digital sector beams based on a result of the beam search procedure.

Another apparatus for wireless communications at a UE is described. The apparatus may include means for receiving, from a base station, a reference signal over a set of resources configured for CSI, generating a set of digital sector beams for a beam search procedure based on a number of antennas of the UE and a Kaiser window configuration, performing the beam search procedure on the received reference signal using the set of digital sector beams, and selecting a first digital sector beam from the set of digital sector beams based on a result of the beam search procedure.

A non-transitory computer-readable medium storing code for wireless communications at a UE is described. The code may include instructions executable by a processor to receive, from a base station, a reference signal over a set of resources configured for CSI, generate a set of digital sector beams for a beam search procedure based on a number of antennas of the UE and a Kaiser window configuration, perform the beam search procedure on the received reference signal using the set of digital sector beams, and select a first digital sector beam from the set of digital sector beams based on a result of the beam search procedure.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for identifying a set of window coefficients of the Kaiser window configuration, and determining a Kaiser window for the beam search procedure based on the set of window coefficients.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for generating the set of digital sector beams using the number of antennas and the Kaiser window.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for generating the set of digital sector beams for the beam search procedure based on a set of discrete Fourier transform (DFT) beams.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, one or more neighboring digital sector beams of the set of digital sector beams cover different numbers of digital reception beams supported by the UE.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the set of digital sector beams include a summation of discrete Fourier transform (DFT) beams.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, performing the beam search procedure may include operations, features, means, or instructions for measuring signal strength of the received reference signal for each of the set of digital sector beams, and selecting the first digital sector beam based on the measured signal strength.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the result of the beam search procedure may be based on the measured signal strength.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, each of the set of digital sector beams overlaps multiple digital reception beams supported by the UE.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for performing a second beam search procedure using a set of digital reception beams of the UE based on the selected first digital sector beam, the set of digital reception beams including one or more digital reception beams at least partially covered by the selected first digital sector beam, determining, based on the second beam search procedure, a precoder matrix index for precoder selection for the UE, the precoder matrix index associated with a digital reception beam of the one or more digital reception beams, and transmitting a report to the base station, where the report includes the precoder matrix index associated with the digital reception beam.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for identifying a set of codebooks associated with the precoder matrix index, and selecting a codebook of the set of codebooks based on the precoder matrix index in the report.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the codebook includes a set of antenna array coefficients.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the report may be a channel state feedback report.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the reference signal may be a CSI reference signal (CSI-RS).

DETAILED DESCRIPTION

A user equipment (UE) may have multiple antenna panels (e.g., antenna modules, antenna arrays) which are used to form a communication beam (e.g., a reception beam or transmission beam) to communicate with a base station using beamforming techniques. As the number of antennas at a UE increases, the time and complexity for determining precoder information for channel feedback may increase, which may cause delays at the UE in providing accurate feedback to the base station. According to some aspects, the UE may perform multiple beam search procedures to determine a precoding matrix indicator (PMI) associated with a digital reception beam. The multiple beam search procedures may include a coarse beam search procedure and a refined beam search procedure, and may reduce the complexity and latency for determining PMI by the UE and providing accurate feedback (e.g., channel state information (CSI)) to the base station.

In some examples, the UE may perform a digital analysis or simulation to determine the precoder information (e.g., PMI) associated with a digital reception beam (e.g., discrete Fourier transform (DFT) beams) appropriate for communications between the UE and the base station. For instance, the UE may select a digital reception beam from a set of digital reception beams based on a measured signal strength of a reference signal for each of the set of digital reception beams, and determine a corresponding PMI for feedback according to the selected digital reception beam. According to some aspects, a base station may transmit a reference signal (e.g., CSI reference signal (CSI-RS)) to the UE, and the UE may perform spatial sectorization by generating digital sector beams covering various receive directions. The digital sector beams may be generated based on the number of antennas of the UE and a Fourier series procedure that uses a Kaiser Window. Some of the digital sector beams vary in size and shape, and may cover different numbers of oversampled digital receptions beams. The UE may measure the signal strength of the CSI-RS for each of the digital sector beams and select a digital sector beam associated with the highest signal quality (highest measured signal strength or receive power, lowest interference, etc.).

Based on the selected digital sector beam, the UE may perform a second beam search procedure (e.g., a refined beam search procedure) using a set of oversampled digital reception beams that correspond to the selected digital sector beam. The refined beam search may include measuring the signal strength of the received reference signal for each of the set of oversampled digital reception beams and identifying or determining the oversampled digital reception beam with the highest signal quality (highest measured signal strength or receive power, lowest interference, etc.). The UE may determine precoder information such as the PMI associated with the determined oversampled digital reception beam and transmit the PMI in a report (e.g., channel state feedback (CSF) report) to the base station. The base station may use the PMI for determining beam parameters such as reception or transmission beam index, reception or transmission beam width, etc. for beamforming communications between the UE and the base station.

Particular aspects of the subject matter described herein may be implemented to realize one or more advantages. The described techniques may support improvements in determining a PMI for channel feedback such as by reducing the complexity and latency at the UE as part of the determination of the PMI, which may reduce power consumption at the UE and improve communication efficiency, among other advantages. As such, supported techniques may include improved network operations and, in some examples, may promote network efficiencies, among other benefits.

Aspects of the disclosure are initially described in the context of wireless communications systems. Additionally, aspects of the disclosure are illustrated through examples of a digital reception beam system and a process flow. Aspects of the disclosure are further illustrated by and described with reference to apparatus diagrams, system diagrams, and flowcharts that relate to beam selection using a window for precoding.

UE115may perform a digital analysis of multiple digital sector beams to determine a PMI associated with a digital reception beam corresponding to a selected digital sector beam. For example, base station105may transmit, to the UE115, a reference signal and the UE115may perform a coarse beam search procedure (e.g., beam estimation) on the reference signal using a set of digital sector beams, which may be generated digitally by the UE115based on the number of antenna panels, antenna elements, etc., a Fourier procedure, and a Kaiser window. The UE115may measure the signal quality of the reference signal for each of the digital sector beams and select the digital sector beam based on the signal quality. The UE115may perform a refined beam search procedure on the selected beam by using a set of oversampled digital reception beams which correspond to the selected digital sector beam. The refined beam search may include measuring the signal quality of the set of oversampled digital reception beams to identify an oversampled digital reception beam based on the signal quality. The UE115may determine the PMI associated with the selected oversampled digital reception beam and transmit the PMI in a report to the base station105.

FIG. 2illustrates an example of a wireless communications system200that supports beam selection using a window for precoding in accordance with aspects of the present disclosure. In some examples, wireless communications system200may implement aspects of wireless communications system100. Wireless communications system200may include a base station105-aand a UE115-a, which may be examples of the corresponding devices as described herein with reference toFIG. 1.

In some cases, UE115-aand base station105-amay communicate using resources of a communication link205. Additionally, or alternatively, the communications on communication link205may be performed using beamforming techniques such as beamformed transmissions as described herein with reference toFIG. 1.

UE115-amay receive transmissions (e.g., CSI-RS) from base station105-avia reception beams215,220, and225. UE115-amay perform a digital simulation with a dual stage DFT beam search to determine a PMI to use for future communications with the base station105-a. The PMI may indicate to base station105-athe reception beams corresponding to the highest signal quality at the UE115-a, which may be used by the base station105-ato select transmission beams for use by the base station105-ain subsequent communications. For instance, the base station105-amay identify or select transmission beams that maximize the transmission energy received via reception beams215,220, or225.

As the number of antennas at UE115-aincrease, the delta between selecting appropriate versus unsuitable precoder information increases as well. The main complexity of feedback (e.g., CSI) in this scenario is a result of the complexity for determining PMI determination, where a majority (e.g., up to 75% or more) of the overall feedback complexity is consumed for PMI selection. As the number of antennas increases, the size of the codebook at the UE115-aalso increases, which introduces complexity in selection of W1as part of the PMI determination. That is, a larger codebook size increases the complexity when selecting W1as part of the PMI determination.

The precoding matrix for Type I single panel codebook may be represented by Equation 1 as follows:

In Equation 1, v denotes the layers and based on the rank and the number of CSI-RS ports, the following of Table 1 apply:

In Table 1, b′k1,k2is an oversampled 2D DFT beam of length

while bk1+k′1,l+k2,land bk1,k2have a length N1N2, cr,vis the cophasing coefficient between polarization, and ψm,lis the cophasing coefficient between antenna groups.

The precoding matrix for Type II codebook per subband, W, may be represented as

Based on the above, Type II can be denoted in a more general form as W=W1W2where W1has size 2N1N2×L, and may be used to capture long-term or wideband properties of the channel, which may be common between different layers, polarizations, or subbands. W1may be represented by Equation 2 as follows:

W2with size L×1 may denote the linear transformation matrix capturing the shorter-term subband properties of the channel and may be represented by Equation 3 as follows:

Based on the codebook structure outline and illustrated by Equations 1, 2, and 3, which may be further extended to multiple panel configurations, the initial stage of precoder selection utilize DFT beam selection. Further, the spectral efficiency (SE) metric computation may be represented by Equation 4 below:

In some cases, the SE metric computation may consume a majority of the overall W1selection cycles (e.g., more than 65% in a 32 antenna port configuration and more than 50% in an 8 antenna port configuration) because all DFT hypothesis are tested. Further, W1selection itself consumes a greater portion of the overall cycles used for generating CSF for high dimension antenna configurations (i.e., as the number of antennas increase at the UE115-a).

To improve CSF generation and PMI selection, aspects of the disclosure provide a dual stage DFT search where a first stage includes a coarse search that is performed based on digital sector beams generated using a Kaiser Window. For instance, a UE115-amay design beams to enable a sectorization of a set of oversampled digital reception beams such that a digital sector beam overlaps or corresponds to multiple oversample digital reception beams. In some examples, the digital sector beams generated by the UE115-aare non-overlapping such that a single oversampled digital reception beam corresponds to a single digital sector beam. Alternatively, some of the digital sector beams may overlap such that one or more oversampled digital reception beams may correspond to multiple digital sector beams. In order to achieve smaller side lobe overlap between multiple digital sector beams, a windowing function such as a Kaiser window may be used in conjunction with a Fourier Series Method to achieve sectorization with relatively small or minimal overlap between digital sector beams.

A second stage includes an exhaustive search performed only in the dominant direction (e.g., corresponding to a selected digital sector beam) selected as part of the first stage. Such techniques may reduce the complexity of the DFT search compared to traditional DFT search procedures, as shown in the example complexity reduction Table 2 below.

According to some aspects, in the first stage, UE115-aperforms a coarse beam search on digital sector beams generated using a Kaiser Window configuration based on a reference signal (e.g., CSI-RS) received from the base station105-a. The coarse beam search may be used to narrow down the spatial direction in which the dominant reception beams are located (e.g., the oversampled digital reception beams). In the second stage, UE115-aperforms a refined beam search on oversampled digital reception beams in the direction of the dominant digital sector beam(s). Based on the refined beam search, UE115-amay determine the PMI associated with an oversampled beam which is in the direction associated with the strongest signal from base station105-a. UE115-amay send the PMI in CSF report210to base station105-a. In some examples, the CSF report210may include the channel quality index (CQI) or the rank indication (RI).

FIG. 3Aillustrates an example of digital reception beam plot300-athat supports beam selection using a window for precoding in accordance with aspects of the present disclosure. In some examples, digital reception beam plot300-amay implement aspects of wireless communications systems100or200.

As illustrated in digital reception beam plot300-a, a UE may perform a digital analysis using multiple digital sector beams, such as digital sector beams305, to determine PMI for the UE. The digital sector beams may be generated by the UE using coefficients for a Kaiser Window configuration. Such coefficients may include antenna coefficients represented by Equation 5 as follows:

and A corresponds to the stopband attenuation, ϕ0is the steering angle, and ϕbis the sector width. The coefficients may also include Kaiser Window coefficients, which may be represented by Equation 6 as follows:

where I0is a 0thorder first kind Bessel function and

After determining the coefficients for the Kaiser Window configuration, the UE may generate the digital sector beams305using a Fourier Series Method and a Kaiser windowing based on the Kaiser Window configuration. For example, the UE may generate digital sector beams305-a,305-b, and305-b, which may at least partially overlap one another. Alternatively, one or more of the digital sector beams305may be non-overlapping.

Additionally, a UE may generate a set of digital reception beams310, each of which may be a digital representation of an antenna configuration for a given reception beam at the UE and may correspond to a given beam direction. In some examples, a digital sector beam305may span or overlap one or more of the set of digital reception beams310. After receiving a signal from the base station, such as a CSI-RS or other signal, the UE may perform an initial (e.g., coarse) beam search using the digital sector beams305(which may overlap one or more of the digital reception beams310), and may measure the received signal at each of the digital sector beams305. Based on the measurements, the UE may select a digital sector beam305for performing a refined beam search procedure (e.g., the UE may select digital sector beam305-a, which may correspond to the highest signal quality or other parameter associated with a given energy threshold (e.g., maximum energy as compared to other digital sector beams305) of the received signal).

FIG. 3Billustrates an example of digital reception beam plot300-bthat supports beam selection using a window for precoding in accordance with aspects of the present disclosure. In some examples, digital reception beam plot300-bmay implement aspects of wireless communications systems100or200.

As illustrated in digital reception beam plot300-b, a UE may perform a digital analysis using multiple digital reception beams, such as oversampled digital reception beams315corresponding to digital sector beam305-a, to determine PMI for the UE. For example, a UE may generate a set of digital reception beams315, each of which may be a digital representation of an antenna configuration for a given reception beam at the UE and may correspond to a given beam direction. In some examples, the set of digital reception beams315may be a subset of the digital reception beams310ofFIG. 3A. After selecting a digital sector beam305for performing a refined beam search procedure (e.g., the UE may select digital sector beam305-a, which corresponds to the highest signal quality or other parameter to maximize the energy of the received signal), as described with respect toFIG. 3A, the UE may perform a refined beam search in direction of digital sector beam305-ato determine an digital reception beam315for which to use for the determination of PMI. The UE may perform a refined digital reception beam search using oversampled digital reception beams315, each of which correspond to the digital sector beam305-aselected as part of the coarse beam search described inFIG. 3A. In some examples, oversampled digital reception beams315may have consecutive beam indices and the UE may measure the received signal using each of oversampled digital reception beams315. Based on the measurements, the UE may select an oversampled digital reception beam, such as oversampled digital reception beam315-a, which may be associated with the highest signal quality (e.g., highest signal strength, highest received power). The UE may then use the selected oversampled digital reception beam315-ato determine PMI, which may be sent to a base station in a CSF report.

FIG. 4illustrates an example of a process flow400that supports beam selection using a window for precoding in accordance with aspects of the present disclosure. In some examples, process flow400may implement aspects of wireless communications systems100or200.

At405, base station105-bmay transmit, to UE115-b, a reference signal (e.g., CSI-RS) over a set of resources configured for a CSI.

At410, UE115-bmay identify a set of coefficients for a Kaiser Window. For example, the UE115-bmay identify antenna coefficients and Kaiser Window coefficients using the techniques described herein. The antenna coefficients may be based at least in part on a sidelobe attenuation associated with the Kaiser Window coefficients.

At415, UE115-bmay determine a Kaiser window configuration for the beam search procedure based on the set of coefficients identified at410.

At420, UE115-bmay generate a set of digital sector beams (e.g., including a summation of DFT beams) for a beam search procedure based on a number of antennas of the UE115-b, a Kaiser Window configuration, a set of DFT beams, a Fourier Series Method, or any combination thereof. In some examples, UE115-bmay generate the set of digital sector beams using the number of antennas and the Kaiser Window. In some cases, one or more neighboring digital sector beams of the set of digital sector beams may cover different numbers of digital reception beams supported by the UE115-b.

At425, UE115-bmay perform the beam search procedure (e.g., a coarse beam search procedure) on the received reference signal using the set of digital sector beams. UE115-bmay perform the beam search procedure by measuring signal strength of the received reference signal for each of the set of digital sector beams. The results of the of the beam search procedure may be based on the measured signal strength. In some examples, each of the set of digital sector beams overlaps multiple digital reception beams supported by the UE115-b.

At430, UE115-bmay select a first digital sector beam from the set of digital sector beams based on a result of the beam search procedure. In some examples, and selecting the first digital sector beam may be based on the measured signal strength.

At435, UE115-bmay perform a refined beam search procedure using a set of digital reception beams of the UE115-bbased on the selected first digital sector beam. In some cases, the set of digital reception beams may include one or more digital reception beams at least partially covered by the selected first digital sector beam.

At440, UE115-bmay determine, based on the refined beam search procedure, a PMI for precoder selection for the UE115-b, the PMI associated with a digital reception beam of the one or more digital reception beams.

At445, UE115-bmay transmit the PMI in a report (e.g., a CSF report) to the base station105-b, where the PMI is associated with the digital reception beam. In some examples, UE115-bmay identify a set of codebooks associated with the PMI and select a codebook of the set of codebooks based on the PMI in the report. The codebook may include a set of antenna array coefficients.

The receiver510may 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 beam selection using a window for precoding, etc.). Information may be passed on to other components of the device505. The receiver510may be an example of aspects of the transceiver820described with reference toFIG. 8. The receiver510may utilize a single antenna or a set of antennas.

The communications manager515may receive, from a base station, a reference signal over a set of resources configured for CSI, generate a set of digital sector beams for a beam search procedure based on a number of antennas of the UE and a Kaiser window configuration, perform the beam search procedure on the received reference signal using the set of digital sector beams, and select a first digital sector beam from the set of digital sector beams based on a result of the beam search procedure. The communications manager515may be an example of aspects of the communications manager810described herein.

In some examples, the communications manager515may be implemented as an integrated circuit or chipset for a mobile device modem, and the receiver510and transmitter520may be implemented as analog components (e.g., amplifiers, filters, antennas) coupled with the mobile device modem to enable wireless transmission and reception over one or more bands.

The communications manager515as described herein may be implemented to realize one or more potential advantages. One implementation may allow the device505to perform beam search procedures and determine a PMI associated with a digital reception beam in an efficient manner. Determining the PMI associated with a selected digital reception beams using a reduced number of DFT hypothesis by generating digital sector beams using a Kaiser window configuration may reduce the latency and complexity of the PMI determination, thereby increasing communication efficiency while maintaining accurate beamforming parameters for communications.

Based on techniques for determining a PMI associated with reception beams as described herein, a processor of a UE115(e.g., controlling the receiver510, the transmitter520, or the transceiver820as described with reference toFIG. 8) may increase reliability and decrease signaling overhead in the communications because the UE115may avoid going through unnecessary computations processes during beamformed communications, which may reduce power consumption at the device505.

The receiver610may 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 beam selection using a window for precoding, etc.). Information may be passed on to other components of the device605. The receiver610may be an example of aspects of the transceiver820described with reference toFIG. 8. The receiver610may utilize a single antenna or a set of antennas.

The communications manager615may be an example of aspects of the communications manager515as described herein. The communications manager615may include a reference signal receiver620, a digital sector beam manager625, a coarse beam search manager630, and a reception beam component635. The communications manager615may be an example of aspects of the communications manager810described herein.

The reference signal receiver620may receive, from a base station, a reference signal over a set of resources configured for CSI.

The digital sector beam manager625may generate a set of digital sector beams for a beam search procedure based on a number of antennas of the UE and a Kaiser window configuration.

The coarse beam search manager630may perform the beam search procedure on the received reference signal using the set of digital sector beams.

The reception beam component635may select a first digital sector beam from the set of digital sector beams based on a result of the beam search procedure.

The transmitter640may transmit signals generated by other components of the device605. In some examples, the transmitter640may be collocated with a receiver610in a transceiver module. For example, the transmitter640may be an example of aspects of the transceiver820described with reference toFIG. 8. The transmitter640may utilize a single antenna or a set of antennas.

FIG. 7shows a block diagram700of a communications manager705that supports beam selection using a window for precoding in accordance with aspects of the present disclosure. The communications manager705may be an example of aspects of a communications manager515, a communications manager615, or a communications manager810described herein. The communications manager705may include a reference signal receiver710, a digital sector beam manager715, a coarse beam search manager720, a reception beam component725, a Kaiser window manager730, a measurement component735, a refined beam search manager740, a matrix module745, a report transmitter750, and a codebook component755. Each of these modules may communicate, directly or indirectly, with one another (e.g., via one or more buses).

The reference signal receiver710may receive, from a base station, a reference signal over a set of resources configured for CSI. In some cases, the reference signal is a CSI-RS.

The digital sector beam manager715may generate a set of digital sector beams for a beam search procedure based on a number of antennas of the UE and a Kaiser window configuration. In some examples, the digital sector beam manager715may generate the set of digital sector beams using the number of antennas and the Kaiser window. In some examples, the digital sector beam manager715may generate the set of digital sector beams for the beam search procedure based on a set of DFT beams. In some cases, one or more neighboring digital sector beams of the set of digital sector beams cover different numbers of digital reception beams supported by the UE. In some cases, the set of digital sector beams include a summation of DFT beams. In some cases, each of the set of digital sector beams overlaps multiple digital reception beams supported by the UE.

The coarse beam search manager720may perform the beam search procedure on the received reference signal using the set of digital sector beams.

The reception beam component725may select a first digital sector beam from the set of digital sector beams based on a result of the beam search procedure. In some examples, the reception beam component725may select the first digital sector beam based on the measured signal strength.

The Kaiser window manager730may identify a set of window coefficients of the Kaiser window configuration. In some examples, the Kaiser window manager730may determine a Kaiser window for the beam search procedure based on the set of window coefficients.

The measurement component735may measure signal strength of the received reference signal for each of the set of digital sector beams. In some cases, the result of the beam search procedure is based on the measured signal strength.

The refined beam search manager740may perform a second beam search procedure using a set of digital reception beams of the UE based on the selected first digital sector beam, the set of digital reception beams including one or more digital reception beams at least partially covered by the selected first digital sector beam.

The matrix module745may determine, based on the second beam search procedure, a precoder matrix index for precoder selection for the UE, the precoder matrix index associated with a digital reception beam of the one or more digital reception beams.

The report transmitter750may transmit a report to the base station, where the report includes the precoder matrix index associated with the digital reception beam. In some cases, the report is a CSF report.

The codebook component755may identify a set of codebooks associated with the precoder matrix index. In some examples, the codebook component755may select a codebook of the set of codebooks based on the precoder matrix index in the report. In some cases, the codebook includes a set of antenna array coefficients.

The communications manager810may receive, from a base station, a reference signal over a set of resources configured for CSI, generate a set of digital sector beams for a beam search procedure based on a number of antennas of the UE and a Kaiser window configuration, perform the beam search procedure on the received reference signal using the set of digital sector beams, and select a first digital sector beam from the set of digital sector beams based on a result of the beam search procedure.

In some cases, the device805may include a single antenna825. However, in some cases, the device805may have more than one antenna825, which may be capable of concurrently transmitting or receiving multiple wireless transmissions.

The memory830may include random access memory (RAM) and read only memory (ROM). The memory830may store computer-readable, computer-executable code835including instructions that, when executed, cause the processor to perform various functions described herein. In some cases, the memory830may contain, among other things, a basic I/O system (BIOS) which may control basic hardware or software operation such as the interaction with peripheral components or devices.

At905, the UE may receive, from a base station, a reference signal over a set of resources configured for CSI. The operations of905may be performed according to the methods described herein. In some examples, aspects of the operations of905may be performed by a reference signal receiver as described with reference toFIGS. 5 through 8.

At910, the UE may generate a set of digital sector beams for a beam search procedure based on a number of antennas of the UE and a Kaiser window configuration. The operations of910may be performed according to the methods described herein. In some examples, aspects of the operations of910may be performed by a digital sector beam manager as described with reference toFIGS. 5 through 8.

At915, the UE may perform the beam search procedure on the received reference signal using the set of digital sector beams. The operations of915may be performed according to the methods described herein. In some examples, aspects of the operations of915may be performed by a coarse beam search manager as described with reference toFIGS. 5 through 8.

At920, the UE may select a first digital sector beam from the set of digital sector beams based on a result of the beam search procedure. The operations of920may be performed according to the methods described herein. In some examples, aspects of the operations of920may be performed by a reception beam component as described with reference toFIGS. 5 through 8.

At1005, the UE may receive, from a base station, a reference signal over a set of resources configured for CSI. The operations of1005may be performed according to the methods described herein. In some examples, aspects of the operations of1005may be performed by a reference signal receiver as described with reference toFIGS. 5 through 8.

At1010, the UE may identify a set of window coefficients of the Kaiser window configuration. The operations of1010may be performed according to the methods described herein. In some examples, aspects of the operations of1010may be performed by a Kaiser window manager as described with reference toFIGS. 5 through 8.

At1015, the UE may determine a Kaiser window for the beam search procedure based on the set of window coefficients. The operations of1015may be performed according to the methods described herein. In some examples, aspects of the operations of1015may be performed by a Kaiser window manager as described with reference toFIGS. 5 through 8.

At1020, the UE may generate a set of digital sector beams for a beam search procedure based on a number of antennas of the UE and a Kaiser window configuration. The operations of1020may be performed according to the methods described herein. In some examples, aspects of the operations of1020may be performed by a digital sector beam manager as described with reference toFIGS. 5 through 8.

At1025, the UE may perform the beam search procedure on the received reference signal using the set of digital sector beams. The operations of1025may be performed according to the methods described herein. In some examples, aspects of the operations of1025may be performed by a coarse beam search manager as described with reference toFIGS. 5 through 8.

At1030, the UE may select a first digital sector beam from the set of digital sector beams based on a result of the beam search procedure. The operations of1030may be performed according to the methods described herein. In some examples, aspects of the operations of1030may be performed by a reception beam component as described with reference toFIGS. 5 through 8.

At1105, the UE may receive, from a base station, a reference signal over a set of resources configured for CSI. The operations of1105may be performed according to the methods described herein. In some examples, aspects of the operations of1105may be performed by a reference signal receiver as described with reference toFIGS. 5 through 8.

At1110, the UE may generate a set of digital sector beams for a beam search procedure based on a number of antennas of the UE and a Kaiser window configuration. The operations of1110may be performed according to the methods described herein. In some examples, aspects of the operations of1110may be performed by a digital sector beam manager as described with reference toFIGS. 5 through 8.

At1115, the UE may generate the set of digital sector beams for the beam search procedure based on a set of DFT beams. The operations of1115may be performed according to the methods described herein. In some examples, aspects of the operations of1115may be performed by a digital sector beam manager as described with reference toFIGS. 5 through 8.

At1120, the UE may perform the beam search procedure on the received reference signal using the set of digital sector beams. The operations of1120may be performed according to the methods described herein. In some examples, aspects of the operations of1120may be performed by a coarse beam search manager as described with reference toFIGS. 5 through 8.

At1125, the UE may select a first digital sector beam from the set of digital sector beams based on a result of the beam search procedure. The operations of1125may be performed according to the methods described herein. In some examples, aspects of the operations of1125may be performed by a reception beam component as described with reference toFIGS. 5 through 8.

At1205, the UE may receive, from a base station, a reference signal over a set of resources configured for CSI. The operations of1205may be performed according to the methods described herein. In some examples, aspects of the operations of1205may be performed by a reference signal receiver as described with reference toFIGS. 5 through 8.

At1210, the UE may generate a set of digital sector beams for a beam search procedure based on a number of antennas of the UE and a Kaiser window configuration. The operations of1210may be performed according to the methods described herein. In some examples, aspects of the operations of1210may be performed by a digital sector beam manager as described with reference toFIGS. 5 through 8.

At1215, the UE may perform the beam search procedure on the received reference signal using the set of digital sector beams. The operations of1215may be performed according to the methods described herein. In some examples, aspects of the operations of1215may be performed by a coarse beam search manager as described with reference toFIGS. 5 through 8.

At1220, the UE may measure signal strength of the received reference signal for each of the set of digital sector beams. The operations of1220may be performed according to the methods described herein. In some examples, aspects of the operations of1220may be performed by a measurement component as described with reference toFIGS. 5 through 8.

At1225, the UE may select the first digital sector beam based on the measured signal strength. The operations of1225may be performed according to the methods described herein. In some examples, aspects of the operations of1225may be performed by a reception beam component as described with reference toFIGS. 5 through 8.