Patent Description:
Aspects of the present disclosure relate to wireless communications, and more particularly, to refinement of transmit beams used for directional transmissions, for example, from a base station to a user equipment (UE) and/or from the UE to the base station.

In some examples, a wireless multiple-access communication system may include a number of base stations, each simultaneously supporting communication for multiple communication devices, otherwise known as user equipment (UEs). In LTE or LTE-A network, a set of one or more base stations may define an eNodeB (eNB). In other examples (e.g., in a next generation or <NUM> network), a wireless multiple access communication system may include a number of distributed units (DUs) (e.g., edge units (EUs), edge nodes (ENs), radio heads (RHs), smart radio heads (SRHs), transmission reception points (TRPs), etc.) in communication with a number of central units (CUs) (e.g., central nodes (CNs), access node controllers (ANCs), etc.), where a set of one or more distributed units, in communication with a central unit, may define an access node (e.g., a new radio base station (NR BS), a new radio node-B (NR NB), a network node, <NUM> NB, gNB, etc.). A base station or DU may communicate with a set of UEs on downlink channels (e.g., for transmissions from a base station or to a UE) and uplink channels (e.g., for transmissions from a UE to a base station or distributed unit).

<CIT> discloses a millimeter Wave (mmW) wireless transmit/receive unit (mWTRU) which may perform an on-demand beam measurement procedure. A measurement request and configuration may be provided by a small cell mmW base station (SCmB). The mWTRU receives a beam measurement request (BMR) on a common control channel, e.g., a common physical downlink directional control channel (PDDCCH) from the SCmB. The BMR may include one or more parameters and/or sets of parameters which may include one or more of an adaptive antenna reference signal (AARS) sequence, time and frequency resource allocations, uplink grants for BMR feedback, reporting quality metric thresholds, number of quality metrics to report, a new or updated BMR indicator, a BMR trigger, and the like. The time and/or frequency resource allocation for the AARS may be considered as a time and/or frequency schedule for the AARS. The mWTRU may decode the common PDDCCH and receive a BMR from the SCmB using a WTRU-specific network identity such as a cell radio network temporary identifier (C-RNTI). The mWTRU may receive the resource allocation and transport format of the common PDDCCH in higher layer signaling such as in a SIB (or in SIBs) which may be broadcast by the SCmB. The mWTRU may sweep receive beams and/or perform measurements. The mWTRU may sweep one or more narrow receive antenna patterns per the BMR time and frequency resource schedule. The mWTRU may measure the scheduled AARS sequence, obtain the beam-pair- specific quality metric per the BMR quality metric to report, filter the quality metric per the BMR reporting quality metric threshold and report the processed measurement results to the SCmB using the uplink grant scheduled in the BMR. The mWTRU may decode the beam pair schedule information on the common PDDCCH. The mWTRU may form the scheduled narrow or multi- lobe broad receive antenna pattern. The mWTRU may decode the dedicated PDDCCH within the formed beam pair to acquire the per-TTI PDDDCH scheduling information. The mWTRU may receive the PDDDCH from the SCmB accordingly. <NPL>, proposes that for beam management, whether CSI-RS in different sub-time-units use the same or different beams should be indicated to UE.

Aspects of the present disclosure provide a method for wireless communications by a user equipment (UE). The method generally includes obtaining information regarding a beam refinement procedure that involves a set of resources for transmitting reference signals (RS), the information indicating which RS resources are to be transmitted by a base station using a same transmit beam, deciding, based on the information, which receive beam or beams to use for reception of the RS resources transmitted by the base station, and receiving the RS resources in accordance with the decision.

Aspects of the present disclosure provide a method for wireless communications by a base station. The method generally includes deciding which transmit beams to use for transmitting reference signal (RS) resources to a user equipment (UE) as part of a beam refinement procedure, providing information to the UE indicating which RS resources are to be transmitted by the base station using a same transmit beam, and transmitting the RS resources in accordance with the decision.

NR may support various wireless communication services, such as Enhanced mobile broadband (eMBB) targeting wide bandwidth (e.g. <NUM> beyond), millimeter wave (mmW) targeting high carrier frequency (e.g. <NUM>), massive MTC (mMTC) targeting non-backward compatible MTC techniques, and/or mission critical targeting ultra reliable low latency communications (URLLC).

<FIG> illustrates an example wireless network <NUM> in which aspects of the present disclosure may be performed. For example, the wireless network may be a new radio (NR) or <NUM> network. NR wireless communication systems may employ beams, where a BS and UE communicate via active beams.

For illustrative purposes, aspects are described with reference to a primary BS and a secondary BS, wherein the secondary BS operates in an mmWave frequency spectrum and the primary BS operations in a lower frequency spectrum that the secondary spectrum; however, aspects may not be limited to this example scenario.

As described herein, for example, with respect to <FIG>, a UE's initial access to a BS communicating via beams may be simplified with assistance from a BS operating in a lower frequency spectrum. With the assistance of the BS operating in a lower frequency spectrum, mmWave resources may be conserved and, in certain scenarios, initial synchronization to the mmWave network may completely or partly be bypassed.

UEs <NUM> may be configured to perform the operations <NUM> and methods described herein for determining a transmit power. BS <NUM> may comprise a transmission reception point (TRP), Node B (NB), <NUM> NB, access point (AP), new radio (NR) BS, Master BS, primary BS, etc.). The NR network <NUM> may include the central unit. The BS <NUM> may perform the operations <NUM> and other methods described herein for providing assistance to a UE in determining a transmit power to use during a RACH procedure with another BS (e.g., a secondary BS).

A UE <NUM> may determine a transmit power for transmitting a message during a RACH procedure with a secondary BS, based at least in part, on communication between the UE and a primary BS. The UE may transmit the message to the secondary BS during the RACH procedure based, at least in part, on the determined transmit power.

A BS <NUM>, such as a master BS or a primary BS, may communicate with the UE and may take one or more actions to assist the UE in setting a transmit power for transmitting a message during the RACH procedure with a secondary BS.

As illustrated in <FIG>, the wireless network <NUM> may include a number of BSs <NUM> and other network entities. According to one example, the network entities including the BS and UEs may communicate on high frequencies (e.g., > <NUM>) using beams. One or more BS may also communicate at a lower frequency (e.g., < <NUM>). The one or more BS configured to operate in a high frequency spectrum and the one or more BS configured to operate in a lower frequency spectrum may be co-located.

A BS may be a station that communicates with UEs. Each BS <NUM> may provide communication coverage for a particular geographic area. In 3GPP, the term "cell" can refer to a coverage area of a Node B and/or a Node B subsystem serving this coverage area, depending on the context in which the term is used. In NR systems, the term "cell" and gNB, Node B, <NUM> NB, AP, NR BS, NR BS, or TRP may be interchangeable. In some examples, a cell may not necessarily be stationary, and the geographic area of the cell may move according to the location of a mobile base station. In some examples, the base stations may be interconnected to one another and/or to one or more other base stations or network nodes (not shown) in the wireless network <NUM> through various types of backhaul interfaces such as a direct physical connection, a virtual network, or the like using any suitable transport network.

The BSs <NUM> may also communicate with one another, e.g., directly or indirectly via wireless or wireline backhaul.

A UE may also be referred to as a mobile station, a terminal, an access terminal, a subscriber unit, a station, a Customer Premises Equipment (CPE), a cellular phone, a smart phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet, a camera, a gaming device, a netbook, a smartbook, an ultrabook, a medical device or medical equipment, a biometric sensor/device, a wearable device such as a smart watch, smart clothing, smart glasses, a smart wrist band, smart jewelry (e.g., a smart ring, a smart bracelet, etc.), an entertainment device (e.g., a music device, a video device, a satellite radio, etc.), a vehicular component or sensor, a smart meter/sensor, industrial manufacturing equipment, a global positioning system device, or any other suitable device that is configured to communicate via a wireless or wired medium. Some UEs may be considered evolved or machine-type communication (MTC) devices or evolved MTC (eMTC) devices. Some UEs may be considered Internet-of-Things (IoT) devices.

For example, the spacing of the subcarriers may be <NUM> and the minimum resource allocation (called a 'resource block') may be <NUM> subcarriers (or <NUM>). Consequently, the nominal FFT size may be equal to <NUM>, <NUM>, <NUM>, <NUM> or <NUM> for system bandwidth of <NUM>, <NUM>, <NUM>, <NUM> or <NUM> megahertz (MHz), respectively. For example, a subband may cover <NUM> (i.e., <NUM> resource blocks), and there may be <NUM>, <NUM>, <NUM>, <NUM> or <NUM> subbands for system bandwidth of <NUM>, <NUM>, <NUM>, <NUM> or <NUM>, respectively.

A single component carrier bandwidth of <NUM> may be supported. NR resource blocks may span <NUM> sub-carriers with a subcarrier bandwidth of <NUM> over a <NUM> duration. Each radio frame may consist of <NUM> subframes with a length of <NUM>. Consequently, each subframe may have a length of <NUM>. Each subframe may indicate a link direction (i.e., DL or UL) for data transmission and the link direction for each subframe may be dynamically switched. Each subframe may include DL/UL data as well as DL/UL control data. UL and DL subframes for NR may be as described in more detail below with respect to <FIG>. Alternatively, NR may support a different air interface, other than an OFDM-based. NR networks may include entities such CUs and/or DUs.

As noted above, a RAN may include a CU and DUs. A NR BS (e.g., gNB, <NUM> Node B, Node B, transmission reception point (TRP), access point (AP)) may correspond to one or multiple BSs. NR cells can be configured as access cell (ACells) or data only cells (DCells). For example, the RAN (e.g., a central unit or distributed unit) can configure the cells. DCells may be cells used for carrier aggregation or dual connectivity, but not used for initial access, cell selection/reselection, or handover. In some cases DCells may not transmit synchronization signals-in some case cases DCells may transmit SS. NR BSs may transmit downlink signals to UEs indicating the cell type. Based on the cell type indication, the UE may communicate with the NR BS. For example, the UE may determine NR BSs to consider for cell selection, access, handover, and/or measurement based on the indicated cell type.

<FIG> illustrates example components of the BS <NUM> and UE <NUM> illustrated in <FIG>, which may be used to implement aspects of the present disclosure. The BS may include a TRP and may be referred to as a Master eNB (MeNB) (e.g., Master BS, primary BS). According to aspects, the Master BS may operate at lower frequencies, for example, below <NUM> and a Secondary BS may operate at higher frequencies, for example, mmWave frequencies above <NUM>. The Master BS and the Secondary BS may be geographically co-located.

One or more components of the BS <NUM> and UE <NUM> may be used to practice aspects of the present disclosure. For example, antennas <NUM>, Tx/Rx <NUM>, processors <NUM>, <NUM>, <NUM>, and/or controller/processor <NUM> of the UE <NUM> and/or antennas <NUM>, processors <NUM>, <NUM>, <NUM>, and/or controller/processor <NUM> of the BS <NUM> may be used to perform the operations described herein and illustrated with reference to <FIG>.

At the base station <NUM>, a transmit processor <NUM> may receive data from a data source <NUM> and control information from a controller/processor <NUM>. The control information may be for the Physical Broadcast Channel (PBCH), Physical Control Format Indicator Channel (PCFICH), Physical Hybrid ARQ Indicator Channel (PHICH), Physical Downlink Control Channel (PDCCH), etc. The data may be for the Physical Downlink Shared Channel (PDSCH), etc. The processor <NUM> may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The processor <NUM> may also generate reference symbols, e.g., for the PSS, SSS, and cell-specific reference signal (CRS).

The processor <NUM> and/or other processors and modules at the base station <NUM> may perform or direct, e.g., the execution of the functional blocks illustrated in <FIG>, and/or other processes for the techniques described herein. The memories <NUM> and <NUM> may store data and program codes for the BS <NUM> and the UE <NUM>, respectively.

The illustrated communications protocol stacks may be implemented by devices operating in a in a <NUM> system.

The DL-centric subframe may also include a common UL portion <NUM>. The common UL portion <NUM> may sometimes be referred to as an UL burst, a common UL burst, and/or various other suitable terms. The common UL portion <NUM> may include feedback information corresponding to various other portions of the DL-centric subframe. For example, the common UL portion <NUM> may include feedback information corresponding to the control portion <NUM>. Non-limiting examples of feedback information may include an ACK signal, a NACK signal, a HARQ indicator, and/or various other suitable types of information. The common UL portion <NUM> may include additional or alternative information, such as information pertaining to random access channel (RACH) procedures, scheduling requests (SRs), and various other suitable types of information. As illustrated in <FIG>, the end of the DL data portion <NUM> may be separated in time from the beginning of the common UL portion <NUM>. One of ordinary skill in the art will understand that the foregoing is merely one example of a DL-centric subframe and alternative structures having similar features may exist without necessarily deviating from the aspects described herein.

<FIG> is a diagram <NUM> showing an example of an UL-centric subframe. The UL -centric subframe may include a control portion <NUM>. The control portion <NUM> may exist in the initial or beginning portion of the UL-centric subframe. The control portion <NUM> in <FIG> may be similar to the control portion described above with reference to <FIG>. The UL-centric subframe may also include an UL data portion <NUM>. The UL data portion <NUM> may sometimes be referred to as the payload of the UL-centric subframe. The UL portion may refer to the communication resources utilized to communicate UL data from the subordinate entity (e.g., UE) to the scheduling entity (e.g., UE or BS). In some configurations, the control portion <NUM> may be a physical UL control channel (PUCCH).

As illustrated in <FIG>, the end of the control portion <NUM> may be separated in time from the beginning of the UL data portion <NUM>. The UL-centric subframe may also include a common UL portion <NUM>. The common UL portion <NUM> in <FIG> may be similar to the common UL portion <NUM> described above with reference to <FIG>. The common UL portion <NUM> may additional or alternative include information pertaining to channel quality indicator (CQI), sounding reference signals (SRSs), and various other suitable types of information. One of ordinary skill in the art will understand that the foregoing is merely one example of an UL-centric subframe and alternative structures having similar features may exist without necessarily deviating from the aspects described herein.

As noted above, in millimeter wave (MMW) cellular systems, beam forming may be needed to overcome high path-losses. Both the base station (BS) and the user equipment (UE) may help find and maintain suitable beams to enable a communication link. A link between the BS and a UE involves a BS beam and a UE beam. The BS beam and the UE beam form what may be referred to as a beam pair link (BPL). For downlink transmissions, a BPL includes a BS transmit beam and a UE receive beam. For uplink transmissions, a BPL includes a UE transmit beam and a BS receive beam,.

As a part of beam management, beams which are used by the BS and UE may be refined from time to time, to help account for changing channel conditions, for example, due to movement of the UE or other objects.

<FIG> graphically illustrates two such beam refinement procedures, referred to as P2 and P3. As illustrated, P2 generally refers to a procedure to refine a transmit beam used by the base station, while P3 generally refers to a procedure to refine a receive beam used by the UE.

As shown in <FIG>, for procedure P2, the BS transmits using different transmit beams. In some cases, the different transmit beams may be selected to be directionally close (around within a few degrees) to an old/current beam (the center beam in <FIG>). In the P2 procedure, the UE keeps its receive beam constant and measures the received power (RSRP) or another channel metric such CQI for each transmitted beam. The UE then identifies the BS beam with the best performance and reports it as feedback to the BS.

As shown in <FIG>, for procedure P3, the BS transmits with a same beam (e.g., the current established beam of the link) while the UE evaluates different receive beams pointing in directions. The UE may choose to evaluate receive beams that are directionally close to an old/current beam (center beam in <FIG>). The UE measures the performance of each beam and chooses the best receive beam. In some cases, the UE may report the performance of new receive beam (or beam pair) to the BS.

In <NUM>-NR the P2/P3 procedures are conducted using channel state information (CSI) reference signal (CSI-RS) transmission bursts. Each CSI-RS burst consists of several (time/frequency) resources. Each resource typically occupies <NUM> symbol period in the time domain and spans a certain bandwidth in the frequency domain. In each resource, the BS will transmit using one or more beams. During CSI-RS setup, the UE typically receives information that allows it to monitor for and process the CSI-RS transmissions. This information typically includes the number of resources involved in a CSI-RS burst, the number of beams transmitted simultaneously by the BS during a resource, and the manner by which the waveforms for the different beams are frequency multiplexed within the resource.

<FIG> show examples how transmit and receive beams may be varied for CSI-RS transmissions during the P2 and P3 procedures. In these relatively simple examples, the BS transmits one beam per resource (a symbol in these examples). As illustrated, the number of beams that are to be evaluated in each procedure may equal the number of symbols/resources of the CSI-RS burst. In the illustrated examples, the CSI-RS symbols are adjacent.

<FIG> illustrates how, during the P2 procedure, the BS changes transmit beams each symbol, while the UE keeps its receive beam the same. <FIG> illustrates how, during the P3 procedure, the BS keeps the transmit beam the same, allowing the UE to evaluate different receive beams in different symbol periods.

The CSI-RS bursts are usually aperiodic and are triggered by a DCI (downlink control information) conveyed through the PDCCH (physical downlink control channel). As will be described below, in some cases, so-called beamforming procedure information (BPI) may need to be conveyed via such DCI. The BPI may indicate whether a base station uses a same transmit beam or a set of different transmit beams for CSI-RS transmissions. This information may help a base station and UE optimize beam refinement procedures.

In cases where several beam pair links (BPLs) have been established between a BS and UE, the BS may need to inform the UE for which BPL a beam refinement is going to be performed. This information may be referred to as QCL (quasi colocation) information. The name refers to the fact that the BS points out to the UE that during the scheduled CSI-RS burst, the BS will use beams that are similar (quasi co-located) to the BS beam used for the specified BPL (e.g., similar in that they are reasonably expected to experience relatively same channel conditions). The QCL information may be conveyed as part of the DCI.

One challenge addressed by aspects of the present disclosure, is the fact that, besides QCL information, no more information regarding the beamforming procedure is typically conveyed to the UE. As a result, the UE may not even know whether a P2 or P3 procedure is being performed, which may make it difficult for the UE to decide which receive beam(s) to use. For example, while the UE may know the current BPL involved and can prepare an adequate receive beam (e.g., beam <MAT> in <FIG>), it may still need to know whether it should keep this beam constant during the entire burst (as it should for the P2 procedure) or whether it should try out alternate receive beams in different symbols (as it should for the P3 procedure).

Aspects of the present disclosure, however, provide beamforming procedure information (BPI) that may help a UE meet the expectation of the BS, for example, by letting the UE know whether the BS is using the same or different beam(s) in all symbols.

In this manner, aspects of the present disclosure may help resolve the ambiguity described above by configuring the BS to convey BPI to indicate which CSI-RS resources (e.g., of a CSI-RS burst) are transmitted using a same BS transmit beam.

<FIG> illustrates example operations <NUM> that may be performed by a user equipment (UE) to perform beam refinement, in accordance with certain aspects of the present disclosure.

Operations <NUM> begin, at <NUM>, by obtaining information regarding a beam refinement procedure that involves a set of RS resources for transmitting RS, the information indicating which RS resources are to be transmitted by a base station using a same transmit beam. At <NUM>, the UE decides, based on the information, which receive beam or set of receive beams to use for reception of the RS resources transmitted by the base station. At <NUM>, the UE receives the RS resources in accordance with the decision. Operations <NUM> may also include updating a UE receive beam of a beam pair link (BPL) based on the RS resource received in accordance with the decision.

<FIG> illustrates example operations <NUM> that may be performed by a base station to configure a UE to perform beam refinement, in accordance with certain aspects of the present disclosure.

Operations <NUM> begin, at <NUM>, by deciding which transmit beams to use for transmitting reference signal (RS) resources to a user equipment (UE) as part of a beam refinement procedure. At <NUM>, the BS provides information to the UE indicating which RS resources are to be transmitted by the base station using a same transmit beam. At <NUM>, the UE transmits the RS resources in accordance with the decision.

In general, aspects of the present disclosure provide that, for CSI-RS transmissions for beam management, the BS conveys BPI to the UE to indicate which CSI-RS resources (if any) are transmitted using the same beam(s). For those resources (transmitted using the same beam), the UE may try out different UE beams during reception (similar to a P3 procedure). On the other hand, any two resources with different BS beams (if any) should be evaluated by the UE using the same UE beam(s) during reception (similar to a P2 procedure).

In either case, the UE may measure the performance of resources, for example, in terms of RSRP or CQI using the best receive beam. The UE may report the performance of the N -best (N=<NUM> in most cases) resources and indicate the resources to the BS.

In some cases, the BPI could be conveyed using just one bit. For example, <NUM> bit could be used to indicate either of the relatively simple P2 / P3 procedures shown in <FIG>. If more elaborate sequences (as described below with reference to <FIG>) are to be used, the BPI may be conveyed using more bits. In any case, this information may be conveyed as DCI or could be conveyed as part of the resource/measurement/reporting (CSI-RS) configuration setup of the UE.

<FIG> illustrate examples of different types of beam sequences that could be used at the BS and UE, with corresponding beam procedure information, according to aspects of the present disclosure.

<FIG> shows an example where a P3 procedure is effectively nested within a P2 procedure. In this example, the beam procedure information (BPI) may indicate to the UE that a first set of resources (e.g., the first three symbols) are transmitted by the BS with the same beam <MAT>. Given this indication, the UE can evaluate different receive beams during the first set of resources (the first three symbols).

The BPI may also indicate that a second set of resources (e.g., the next three symbols) also are transmitted with the same BS beam <MAT>. This enables the UE to first find the best UE beam for the different transmit beams <MAT> and <MAT> individually, and then compare the performance, which may lead to efficient beam pair link (BPL selection). Ultimately, the best BS beam may be determined, for each set of symbols, and reported together with its performance metric.

While the example of <FIG> shows the UE evaluating the same receive beam for each set of symbols, in some cases, the UE may choose or decide on a different set of receive beams for the second set of symbols than the first set (e.g., a subset or superset of the received beams evaluated during the first set of symbols or a completely different set).

<FIG> illustrates another example, where the BS transmits different beams (e.g., <NUM> beams) per CSI-RS resource. In this example, the waveforms of the beams are frequency multiplexed. Procedurally, this may be effectively considered a P2 procedure nested within a P3 procedure, since during every symbol, a P2 sweep (of different transmit beams) is conducted in the "frequency domain. " Across time, a P3 procedure is performed, with different receive beams evaluated across three symbols.

In this example, the BPI may indicate to the UE that all resources are transmitted with the same BS beams and, therefore, the UE can and should evaluate different receive beams for each resource. In this case, the BPI will be the same as the BPI for the case shown in <FIG>. Since the waveforms of the BS beams are frequency multiplexed, the UE can measure the performance of each BS beam separately. For ease of measurement and reporting procedures within the CSI-RS framework, each resource may effectively be split into <NUM> resources, where each new resource contains the waveform of a single BS beam.

<FIG> illustrates another example where the BS transmits one beam per resource, but the waveform is periodic in the time domain, such that <NUM> periods fit in one symbol (thus each period may be referred to as a sub-symbol). As illustrated, this approach enables the UE to evaluate three different beams (one per sub-symbol). Thus, procedurally this approach may be considered as performing a P3 sweep within a P2 sweep.

The periodicity of the waveform shown in <FIG> may be achieved by occupying only every n-th subcarrier (e.g., using a comb structure), where n=<NUM> in this example. During CSI-RS setup, the UE may be informed of how the subcarriers of each resource are occupied (e.g., a periodicity of how RS is repeated in each symbol/sub-symbol). In such cases, this information does not need to be conveyed in the BPI. Given this information, the UE may know that it can evaluate different UE beams, per resource (symbol).

In the example shown in <FIG>, the BPI may indicate to the UE that each resource has different beams. This means, for the UE, that it may need to use the same RX-beams ( <MAT>) for each resource. Also, in this example, the UE may report the best possible BS beam and its performance (when combined with the best possible receive beam).

In some cases, information regarding a transmit beam pattern (or patterns) used (across frequencies, symbols, or sub-symbols) for any of the techniques described herein may be provided as an index into a table. The table may list different combinations of transmit beam patterns for transmitting the RS resources and providing an index may be an efficient mechanism to signal a particular combination from the table (e.g., using only a few bits).

As described herein, by providing BPI, a UE may be able to intelligently select receive beams to evaluate during a beam refinement procedure.

The phrase computer readable medium does not refer to a transitory propagating signal.

For example, instructions for perform the operations described herein and illustrated in <FIG>.

Claim 1:
A method (<NUM>) for wireless communication by a user equipment, UE, comprising:
obtaining (<NUM>) from a base station information regarding a beam refinement procedure of an established beam pair link, BPL, between the UE and the base station, wherein the beam refinement procedure involves a set of reference signal, RS, resources for transmitting RS, the information indicating whether RS resources are to be transmitted by the base station using a same transmit beam or a set of different transmit beams; wherein the information is provided as an index into a table with different combinations of transmit beam patterns for transmitting the RS resources; wherein the beam patterns are transmitted across frequencies, symbols, or sub-symbols;
deciding (<NUM>), based on the information, which receive beam or set of receive beams to use for reception of the RS resources transmitted by the base station; and
receiving (<NUM>) the RS resources in accordance with the decision.