IDENTIFYING A DEFAULT BEAM FOR COMMUNICATIONS ON A PHYSICAL DOWNLINK SHARED CHANNEL (PDSCH)

Aspects of the present disclosure provide apparatus, methods, processing systems, and computer readable mediums for selecting a default beam for communications between a user equipment (UE) and network entity on a physical downlink shared channel (PDSCH). An example method generally includes receiving, from a network entity, configuration information, selecting a default beam based on the configuration information, wherein the default beam is selected for use across a plurality of time periods, and receiving a physical downlink shared channel (PDSCH) using the default beam across the plurality of time periods.

TECHNICAL FIELD

Aspects of the present disclosure relate to wireless communications, and more particularly, to techniques for identifying and using a default beam for transmitting and receiving communications on a physical downlink shared channel (PDSCH).

BACKGROUND

However, as the demand for mobile broadband access continues to increase, further improvements, e.g., improvements in latency, reliability, and the like, in NR and LTE technology remain useful. Preferably, these improvements should be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.

A control resource set (CORESET) for systems, such as an NR and LTE systems, may comprise one or more control resource (e.g., time and frequency resources) sets, configured for conveying PDCCH, within the system bandwidth. Within each CORESET, one or more search spaces (e.g., common search space (CSS), UE-specific search space (USS), etc.) may be defined for a given UE.

SUMMARY

One innovative aspect of the subject matter described in this disclosure can be implemented in a method for wireless communications by a user equipment (UE). The method generally includes receiving, from a network entity, configuration information, selecting a default beam based on the configuration information, wherein the default beam is selected for use across a plurality of time periods, and receiving a physical downlink shared channel (PDSCH) using the default beam across the plurality of time periods.

One innovative aspect of the subject matter described in this disclosure can be implemented in a method for wireless communications by a network entity. The method generally includes transmitting, to a user equipment (UE), configuration information that the UE can use to identify a default beam for receiving a physical downlink shared channel (PDSCH), selecting a default beam based on the configuration information, wherein the default beam is selected for use across a plurality of time periods, and transmitting the PDSCH using the default beam across the plurality of time periods.

One innovative aspect of the subject matter described in this disclosure can be implemented in a user equipment (UE). The UE generally includes means for receiving, from a network entity, configuration information, means for selecting a default beam based on the configuration information, wherein the default beam is selected for use across a plurality of time periods, and means for receiving a physical downlink shared channel (PDSCH) using the default beam across the plurality of time periods.

One innovative aspect of the subject matter described in this disclosure can be implemented in a network entity. The network entity generally includes means for transmitting, to a user equipment (UE), configuration information that the UE can use to identify a default beam for receiving a physical downlink shared channel (PDSCH), means for selecting a default beam based on the configuration information, wherein the default beam is selected for use across a plurality of time periods, and means for transmitting the PDSCH using the default beam across the plurality of time periods.

One innovative aspect of the subject matter described in this disclosure can be implemented in a user equipment (UE). The UE generally includes a receiver, a memory having instructions stored thereon, and at least one processor configured to execute the executable instructions to cause: the receiver to receive, from a network entity, configuration information the at least one processor to select a default beam based on the configuration information, wherein the default beam is selected for use across a plurality of time periods, and the receiver to receive a physical downlink shared channel (PDSCH) using the default beam across the plurality of time periods.

One innovative aspect of the subject matter described in this disclosure can be implemented in a network entity. The network entity generally includes a transmitter, a memory having executable instructions stored thereon, and at least one processor configured to execute the executable instructions to cause: the transmitter to transmit, to a user equipment (UE), configuration information, the at least one processor to select a default beam based on the configuration information, wherein the default beam is selected for use across a plurality of time periods, and the transmitter to transmit a physical downlink shared channel (PDSCH) using the default beam across the plurality of time periods.

One innovative aspect of the subject matter described in this disclosure can be implemented in an apparatus for wireless communications by a user equipment (UE). The apparatus generally includes an interface configured to obtain, from a network entity, configuration information, a memory having instructions stored thereon, and at least one processor configured to execute the instructions to cause the apparatus to: select a default beam based on the configuration information, wherein the default beam is selected for use across a plurality of time periods and obtain a physical downlink shared channel (PDSCH) using the default beam across the plurality of time periods.

One innovative aspect of the subject matter described in this disclosure can be implemented in an apparatus for wireless communications by a network entity. The apparatus generally includes an interface configured to output, for transmission to a user equipment (UE), configuration information, a memory having instructions stored thereon, and at least one processor configured to execute the instructions to cause the apparatus to: select a default beam based on the configuration information, wherein the default beam is selected for use across a plurality of time periods; and initiate a transmission of a physical downlink shared channel (PDSCH) via the default beam across the plurality of time periods.

One innovative aspect of the subject matter described in this disclosure can be implemented in a computer-readable medium for wireless communications by an apparatus. The computer-readable medium generally includes instructions executable by the apparatus to obtain, from a network entity, configuration information, select a default beam based on the configuration information, wherein the default beam is selected for use across a plurality of time periods, and obtain a physical downlink shared channel (PDSCH) using the default beam across the plurality of time periods.

One innovative aspect of the subject matter described in this disclosure can be implemented in a computer-readable medium for wireless communications by an apparatus. The computer-readable medium generally includes instructions executable by the apparatus to output, for transmission to a user equipment (UE), configuration information, select a default beam based on the configuration information, wherein the default beam is selected for use across a plurality of time periods, and initiate a transmission of a physical downlink shared channel (PDSCH) via the default beam across the plurality of time periods.

Aspects of the present disclosure provide means for, apparatus, processors, and computer-readable mediums for performing the methods described herein.

To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the appended drawings set forth in detail some illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of various aspects may be employed.

DETAILED DESCRIPTION

Aspects of the present disclosure provide apparatus, methods, processing systems, and computer readable mediums for identifying and using a default beam to transmit and receive a physical downlink shared channel (PDSCH).

The following description provides examples of identifying and using a default beam to transmit and receive a physical downlink shared channel (PDSCH), and is not limiting of the scope, applicability, or examples set forth in the claims. Changes may be made in the function and arrangement of elements discussed without departing from the scope of the disclosure. Various examples may omit, substitute, or add various procedures or components as appropriate. For instance, the methods described may be performed in an order different from that described, and various steps may be added, omitted, or combined. Also, features described with respect to some examples may be combined in some other examples. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such an apparatus or method which is practiced using other structure, functionality, or structure and functionality in addition to, or other than, the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim.

FIG. 1illustrates an example wireless communication network100in which aspects of the present disclosure may be performed. For example, as shown inFIG. 1, UE120amay include a rate matching module122that may be configured to perform (or cause UE120ato perform) operations400ofFIG. 4. Similarly, a base station110amay include a rate matching configuration module112that may be configured to transmit a DCI to UE120ato schedule a PDSCH and cause the UE to perform operations500ofFIG. 5.

NR access (for example, 5G NR) may support various wireless communication services, such as enhanced mobile broadband (eMBB) targeting wide bandwidth (for example, 80 MHz or beyond), millimeter wave (mmWave) targeting high carrier frequency (for example, 25 GHz or beyond), massive machine type communications MTC (mMTC) targeting non-backward compatible MTC techniques, or mission critical services targeting ultra-reliable low-latency communications (URLLC). These services may include latency and reliability requirements. These services may also have different transmission time intervals (TTI) to meet respective quality of service (QoS) requirements. In addition, these services may co-exist in the same time-domain resource (for example, a slot or subframe) or frequency-domain resource (for example, component carrier).

Wireless communication network100may also include relay stations (for example, relay station110r), also referred to as relays or the like, that receive a transmission of data or other information from an upstream station (for example, a BS110aor a UE120r) and sends a transmission of the data or other information to a downstream station (for example, a UE120or a BS110), or that relays transmissions between UEs120, to facilitate communication between devices.

A network controller130may couple to a set of BSs110and provide coordination and control for these BSs110. The network controller130may communicate with the BSs110via a backhaul. The BSs110may also communicate with one another (for example, directly or indirectly) via wireless or wireline backhaul.

FIG. 2shows a block diagram illustrating an example base station (BS) and an example user equipment (UE) in accordance with some aspects of the present disclosure.

At the BS110, a transmit processor220may receive data from a data source212and control information from a controller/processor240. 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), group common PDCCH (GC PDCCH), etc. The data may be for the physical downlink shared channel (PDSCH), etc. The processor220may process (for example, encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The transmit processor220may also generate reference symbols, such as for the primary synchronization signal (PSS), secondary synchronization signal (SSS), and cell-specific reference signal (CRS). A transmit (TX) multiple-input multiple-output (MIMO) processor230may perform spatial processing (for example, precoding) on the data symbols, the control symbols, or the reference symbols, if applicable, and may provide output symbol streams to the modulators (MODs)232a-232t. Each modulator232may process a respective output symbol stream (for example, for OFDM, etc.) to obtain an output sample stream. Each modulator may further process (for example, convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. Downlink signals from modulators232a-232tmay be transmitted via the antennas234a-234t, respectively.

The memories242and282may store data and program codes for BS110and UE120, respectively. A scheduler244may schedule UEs for data transmission on the downlink or uplink. In one example, memory282or memory242can be a non-transitory computer-readable medium comprising instructions (e.g., instructions that instruct a processor, e.g., controller/processor680, controller/processor640, or other processor) to perform any aspects ofFIG. 4orFIG. 5. Additionally or alternatively, such instructions may be copied or installed onto memory282or memory242from a non-transitory computer-readable medium.

The controller/processor280or other processors and modules at the UE120may perform or direct the execution of processes for the techniques described herein. As shown inFIG. 2, the controller/processor280of the UE120has default beam identifier122that may be configured to perform operations400ofFIG. 4, as discussed in further detail below. The controller/processor240of the base station110includes a default beam identifier112that may be configured perform operations500ofFIG. 5, as discussed in further detail below. Although shown at the Controller/Processor, other components of the UE or BS may be used to perform the operations described herein.

FIG. 3is a diagram showing an example of a frame format300for NR. The transmission timeline for each of the downlink and uplink may be partitioned into units of radio frames. Each radio frame may have a predetermined duration (e.g., 10 ms) and may be partitioned into 10 subframes, each of 1 ms, with indices of 0 through 9. Each subframe may include a variable number of slots depending on the subcarrier spacing. Each slot may include a variable number of symbol periods (e.g., 7 or 14 symbols) depending on the subcarrier spacing. The symbol periods in each slot may be assigned indices. A mini-slot, which may be referred to as a sub-slot structure, refers to a transmit time interval having a duration less than a slot (e.g., 2, 3, or 4 symbols).

In NR, a synchronization signal (SS) block is transmitted. The SS block includes a PSS, a SSS, and a two symbol PBCH. The SS block can be transmitted in a fixed slot location, such as the symbols 0-3 as shown inFIG. 3. The PSS and SSS may be used by UEs for cell search and acquisition. The PSS may provide half-frame timing, the SS may provide the CP length and frame timing. The PSS and SSS may provide the cell identity. The PBCH carries some basic system information, such as downlink system bandwidth, timing information within radio frame, SS burst set periodicity, system frame number, etc. The SS blocks may be organized into SS bursts to support beam sweeping. Further system information such as, remaining minimum system information (RMSI), system information blocks (SIBs), other system information (OSI) can be transmitted on a physical downlink shared channel (PDSCH) in certain subframes. The SS block can be transmitted up to sixty-four times, for example, with up to sixty-four different beam directions for mmW. The up to sixty-four transmissions of the SS block are referred to as the SS burst set. SS blocks in an SS burst set are transmitted in the same frequency region, while SS blocks in different SS bursts sets can be transmitted at different frequency locations.

A control resource set (CORESET) for systems, such as an NR and LTE systems, may comprise one or more control resource (e.g., time and frequency resources) sets, configured for conveying PDCCH, within the system bandwidth. Within each CORESET, one or more search spaces (e.g., common search space (CSS), UE-specific search space (USS), etc.) may be defined for a given UE. According to aspects of the present disclosure, a CORESET is a set of time and frequency domain resources, defined in units of resource element groups (REGs). Each REG may comprise a fixed number (e.g., twelve) tones in one symbol period (e.g., a symbol period of a slot), where one tone in one symbol period is referred to as a resource element (RE). A fixed number of REGs may be included in a control channel element (CCE). Sets of CCEs may be used to transmit new radio PDCCHs (NR-PDCCHs), with different numbers of CCEs in the sets used to transmit NR-PDCCHs using differing aggregation levels. Multiple sets of CCEs may be defined as search spaces for UEs, and thus a NodeB or other base station may transmit an NR-PDCCH to a UE by transmitting the NR-PDCCH in a set of CCEs that is defined as a decoding candidate within a search space for the UE, and the UE may receive the NR-PDCCH by searching in search spaces for the UE and decoding the NR-PDCCH transmitted by the NodeB.

Example Methods for Identifying a Default Beam for a Physical Downlink Shared Channel (PDSCH)

Aspects of the present disclosure provide apparatus, methods, processing systems, and computer readable mediums for identifying and using a default beam to transmit and receive a physical downlink shared channel (PDSCH).

In various wireless standards, a default beam may be defined for channels such as the physical downlink shared channel (PDSCH). The default beam may be a beam that a network entity uses to transmit a PDSCH, and correspondingly that a user equipment uses to receive the PDSCH, in the absence of an indication of a different beam to use for transmitting (and receiving) the PDSCH.

Various rules may define how the default beam can be selected for a scheduled transmission of a PDSCH. In a first scenario, a default beam may be selected and used when a time offset between transmission of downlink control information (DCI) and a PDSCH scheduled by the DCI is less than a threshold value. In this scenario, the default beam used for the scheduled PDSCH may be defined as the beam associated with a control resource set (CORESET) having a lowest identifier within the latest monitored slot. Because different CORESETs may be monitored in different slots, the default beam may not be fixed across slots.

In a second scenario, a default beam may be selected in an environment where a UE is served by multiple network entities (e.g., transmit-receive points (TRPs)). Up to two TRPs per cell may be supported. Where the multiple TRPs transmit multiple DCIs scheduling multiple PDSCHs, the CORESETs may be divided into two pools. Each CORESET may be associated with a CORESET pool index, and each pool may be associated with or otherwise correspond to one of the multiple TRPs. Scheduling information carried on a physical downlink control channel (PDCCH) for a specific CORESET generally schedules the PDSCH for that specific CORESET, and the default beam for a specific TRP may be the beam associated with the CORESET with a lowest CORESET identifier from the CORESET pool associated with that specific TRP when any CORESET in the CORESET pool is monitored. In a multi-TRP scenario, the default beam may still vary across slots.

In some cases, the multiple TRPs may use a single DCI. A transmission configuration indicator (TCI) codepoint may be defined with a plurality of TCI states, and each TCI state may correspond to a beam from a TRP. For example, where two TRPs in a cell are supported and use a single DCI, a first TCI state may correspond to a beam from a first TRP of the two TRPs, and a second TCI state may correspond to a beam from a second TRP of the two TRPs. The default beam pairs from the TRPs may be the beams associated with the active TCI codepoint having a plurality of TCI states and being the lowest identifier of the plurality of TCI codepoints. In this scenario, the default beam may be fixed across slots and may not change due to changes in the monitored CORESETs.

To simplify beam management across slots, the default beam for a PDSCH may be fixed across slots. Fixing the default beam across slots generally allows a network entity (e.g., a gNodeB) to configure and use a beam having good signal strength characteristics (e.g., a reference signal received power (RSRP) above a threshold strength) as the default beam; because this beam generally has good signal strength characteristics, it may be assumed that UEs will be able to successfully receive signaling transmitted using the default beam. Further, the use of a default beam having good signal strength characteristics may allow for the signal-to-noise ratio of received signaling to be maximized across slots for joint combining or cross-slot reception. This may provide various benefits, for example, at higher subcarrier spacing (SCSs) (e.g., 480 kHz and 960 kHz spacing at higher bands, such as the 52.7 GHz-72.1 GHz bands). For example, given a quasicolocation (QCL) duration, the user of higher subcarrier spacings at higher bands may shorten the symbol length; however, the threshold time for a default beam to be used may be the same, meaning that more slots may be included in the threshold time for the default beam. Further, higher bands may have various coverage limitations, and to ameliorate these coverage limitations, multiple slots may be combined to increase the signal-to-noise ratio of a received signal.

A default beam that is invariant across slots may be determined based on one or more rules. In one example, the fixed default beam for a PDSCH may be determined based on a TCI state. For example, the fixed default beam may be the beam associated with an active PDSCH TCI having a lowest identifier in an active bandwidth part (BWP). In another example, the fixed default beam may be determined based on a CORESET identifier. For example, the fixed default beam may be the beam associated with a CORESET having a lowest CORESET identifier in the active BWP.

Fixed, invariant default beams across slots may simplify beam selection. However, using a fixed default beam may not be optimal in various scenarios. For example, a fixed default beam may reduce spatial diversity; in contrast, using different default beams for different slots may improve spatial diversity and mitigate problems that may arise against channel blockages. Further, a fixed default beam for a PDSCH may entail beam switching, which may impact intersymbol interference (e.g., in higher frequency bands, where the cyclic prefix is smaller due to smaller symbol lengths). For example, in one case, the default beam for the PDSCH may follow the PDCCH beam in the beginning of the same slot, which may allow for the avoidance of beam switching before the first symbol of the PDSCH; however, beam switching may be needed in other situations, as different beams may be used for the PDSCH and PDCCH.

Fixed, invariant default beams across slots may also not be optimal in beam failure recovery scenarios. After recovery from a beam failure (e.g., a scenario in which a signal quality metric, such as RSRP, for a monitored beam in a cell falls below a threshold value), the original TCI state configuration may no longer be valid. However, there may be a timing gap between beam failure recovery and TCI state reconfiguration, during which time a fixed default beam may not be an optimal beam for use in communicating between a network entity and a UE.

Aspects of the present disclosure provide techniques for dynamically selecting and using an active default beam for communications between a network entity and a user equipment. By allowing for default beams to be dynamically selected, the default beam selected for a UE may account for various capabilities of the UE, channel conditions, and other information. Further, allowing for dynamic selection and use of default beams for communications between a network entity and a UE may improve spatial diversity, mitigate the impact of beam switching on intersymbol interference, and provide other improvements to wireless communications.

FIG. 4illustrates example operations400that may be performed by a user equipment (UE) for selecting a default beam and communicating with a network entity using the default beam, according to certain aspects described herein.

As illustrated, operations400may begin at block402, where the UE receives, from a network entity, configuration information. As discussed in further detail below, the configuration information generally includes information identifying a default beam for the UE to use and/or one or more rules for selecting the default beam.

At block404, the UE selects a default beam based on the configuration information. Generally, the default beam may be selected for use across a plurality of time periods. For example, the default beam may be selected for use across a plurality of slots. In some aspects, the default beam may be selected for use when a time offset between a physical downlink shared channel (PDSCH) and a physical downlink control channel (PDCCH) is shorter than a threshold amount of time, which may be based on UE capability information.

At block406, the UE receives a PDSCH using the default beam across the plurality of time periods.

FIG. 5illustrates example operations500that may be performed by a network entity for selecting a default beam and communicating with a user equipment (UE) using the selected default beam, according to certain aspects described herein.

As illustrated, operations500may begin at block502where the network entity transmits, to a user equipment (UE), configuration information.

At block504, the network entity selects a default beam based on the configuration information. As discussed, the default beam is generally selected for use across a plurality of time periods.

At block506, the network entity transmits a physical downlink shared channel (PDSCH) using the default beam across the plurality of time periods.

In some aspects, the configuration information may include information identifying a default beam. The identified default beam may be selected by the network entity based on UE capabilities. For example, the network entity can determine which beam to use as a default beam (and thus, to signal to the UE) based, for example, on which methods for selecting a default beam that the UE supports, a UE capability to perform beam switching and/or soft-combining, or the like.

In some aspects, the configuration information may include information specifying one or more rules for selecting the default beam. The rules may specify, for example, that when tone spacing or symbol length is smaller than a threshold tone spacing or symbol length, the fixed default beam may be deselected. In some aspects, the rules may be based on whether the UE is operating within a first frequency band or a second frequency band. For example, if the UE is operating in the first frequency band (e.g., below 52.6 GHz), the default beam may be selected based on a CORESET identifier of a latest monitored slot. If the UE is operating in the second frequency band (e.g., above 52.6 GHz), the default beam may be selected as the beam associated with a TCI state with a lowest identifier in an active BWP or the beam associated with a CORESET with a lowest identifier in the active BWP.

In some aspects, a default mode for selecting the default beam may be used for initial access by the UE to a network entity (e.g., until the UE receives configuration information from the network entity identifying a default beam or a technique for selecting the default beam, or some other indication to use a fixed beam across slots). For example, the UE may be configured a priori or via information carried in a system information block (SIB) to select the default beam as a beam associated with a CORESET with a lowest identifier in a latest monitored slot. The default beam may differ for different configurations, such as frequency bands and subcarrier spacings. In another example, the default mode may specify that the default beam comprises a fixed beam associated with a TCI state having a lowest identifier in the active BWP.

In some aspects, the configuration information may include one or more rules for selecting the default beam in response to a BFR event. Generally, these rules for selecting the default beam in response to a BFR event may apply between beam failure recovery and receipt, from the network entity, of an indication of a default beam to use or rules for selecting the default beam. In one example, the rules may specify that when a default beam used prior to the BFR event is selected based on a TCI state, the default beam selected after the BFR event may be the beam associated with a CORESET having a lowest identifier for a latest monitored slot or a beam associated with a CORESET having a lowest identifier in an active BWP. In another example, when the default beam prior to the BFR is fixed (e.g., using a TCI state to determine the default beam), the default beam after the BFR event may be selected as a beam associated with a CORESET having a lowest identifier for a latest monitored slot. This default beam may be used, for example, until the UE receives an indication to use a fixed beam across slots or until UE receives reconfiguration of TCI states.

In some aspects, the UE may indicate, to the network entity, UE capability for dynamically changing rules for selecting the default beam. The network entity may transmit configuration information identifying rules for selecting the default beam based on the indicated UE capability for dynamically changing these rules. For example, the network entity may indicate that a default beam is fixed across slots where a UE indicates that it does not support dynamically changing rules for selecting the default beam or has limited support for dynamically changing rules for selecting the default beam. Similarly, the network entity may specify which rules the UE is to use in identifying a default beam in configuration information provided to the UE if the UE indicates that it does support dynamically changing rules for selecting the default beam.

FIG. 6illustrates a communications device600that may include various components (e.g., corresponding to means-plus-function components) configured to perform operations for the techniques disclosed herein, such as the operations illustrated inFIG. 4. The communications device600includes a processing system602coupled to a transceiver608. The transceiver608is configured to transmit and receive signals for the communications device600via an antenna610, such as the various signals as described herein. The processing system602may be configured to perform processing functions for the communications device600, including processing signals received and/or to be transmitted by the communications device600.

The processing system602includes a processor604coupled to a computer-readable medium/memory612via a bus606. In certain aspects, the computer-readable medium/memory612is configured to store instructions (e.g., computer-executable codes) that when executed by the processor604, cause the processor604to perform the operations illustrated inFIG. 4, or other operations for performing the various techniques discussed herein for identifying a default beam for use in communications between a network entity and a user equipment. In certain aspects, computer-readable medium/memory612stores code620for obtaining configuration information; code622for selecting a default beam based on the configuration information; and code624for obtaining a physical downlink shared channel (PDSCH) using the default beam. In certain aspects, the processor604has circuitry configured to implement the code stored in the computer-readable medium/memory612. The processor604includes circuitry630for obtaining configuration information; circuitry632for selecting a default beam based on the configuration information; and circuitry634for obtaining a physical downlink shared channel (PDSCH) using the default beam.

FIG. 7illustrates a communications device700that may include various components (e.g., corresponding to means-plus-function components) configured to perform operations for the techniques disclosed herein, such as the operations illustrated inFIG. 5. The communications device700includes a processing system702coupled to a transceiver708. The transceiver708is configured to transmit and receive signals for the communications device700via an antenna710, such as the various signals as described herein. The processing system702may be configured to perform processing functions for the communications device700, including processing signals received and/or to be transmitted by the communications device700.

The processing system702includes a processor704coupled to a computer-readable medium/memory712via a bus706. In certain aspects, the computer-readable medium/memory712is configured to store instructions (e.g., computer-executable codes) that when executed by the processor704, cause the processor704to perform the operations illustrated inFIG. 5, or other operations for identifying a default beam for use in communications between a network entity and a user equipment. In certain aspects, computer-readable medium/memory712stores code720for outputting, for transmission, configuration information; code722for selecting a default beam based on the configuration information; and code724for initiating a transmission of a physical downlink shared channel (PDSCH) via the default beam. In certain aspects, the processor704has circuitry configured to implement the code stored in the computer-readable medium/memory712. The processor704includes circuitry730for outputting, for transmission, configuration information; circuitry722for selecting a default beam based on the configuration information; and circuitry724for initiating a transmission of a physical downlink shared channel (PDSCH) via the default beam.

Example Aspects

In addition to the various aspects described above, aspects of specific combinations are within the scope of the disclosure, some of which are detailed below:

Aspect 1: A method for wireless communications by a user equipment (UE), comprising: receiving, from a network entity, configuration information; selecting a default beam based on the configuration information, wherein the default beam is selected for use across a plurality of time periods; and receiving a physical downlink shared channel (PDSCH) using the default beam across the plurality of time periods.

Aspect 2: The method of Aspect 1, wherein the configuration information includes information identifying a beam selected based on UE capability information as the default beam.

Aspect 3: The method of any one of Aspects 1-2, wherein the configuration information identifies one or more rules for selecting the default beam.

Aspect 4: The method of Aspect 3, wherein the one or more rules comprise a rule for selecting the default beam based on whether the UE is operating in a first frequency band or a second frequency band.

Aspect 5: The method of Aspect 4, wherein the rule specifies that the default beam is selected based on a control resource set (CORESET) identifier of a latest monitored slot when the UE is operating in the first frequency band.

Aspect 6: The method of Aspect 4, wherein the rule specifies, when the UE is operating in the second frequency band, the default beam comprises a fixed beam associated with at least one of a transmission configuration indicator (TCI) state with a lowest identifier in an active bandwidth part (BWP) or a control resource set (CORESET) with a lowest identifier in the active BWP.

Aspect 7: The method of any one of Aspects 1-6, wherein the configuration information comprises an indication to select the default beam as a beam associated with a control resource set (CORESET) with a lowest identifier in a latest monitored slot until the UE receives another indication to use a fixed beam across slots.

Aspect 8: The method of any one of Aspects 1-7, wherein the configuration information includes one or more rules for selecting the default beam in response to a beam failure recovery (BFR) event.

Aspect 9: The method of Aspect 8, wherein the one or more rules specify that when a default beam prior to the BFR event is selected based on a transmission configuration indicator (TCI) state, the default beam is selected as a beam associated with a control resource set (CORESET) having a lowest identifier for a latest monitored slot or a beam associated with a CORESET having a lowest identifier in an active bandwidth part (BWP).

Aspect 10: The method of Aspect 8, wherein the one or more rules specify that when a default beam prior to the BFR event is fixed, the default beam is selected as a beam associated with a control resource set (CORESET) having a lowest identifier for a latest monitored slot until the UE receives an indication to use a fixed beam across slots.

Aspect 11: The method of any one of Aspects 1-10, further comprising: indicating, to the network entity, UE capability for dynamically changing one or more rules associated with the selection of the default beam.

Aspect 12: The method of any one of Aspects 1-11, further comprising: prior to receiving the configuration information, selecting an initial default beam based on a default rule.

Aspect 13: The method of Aspect 12, wherein the default rule specifies that the default beam comprises a fixed beam associated with a control resource set (CORESET) with a lowest identifier in an active bandwidth part (BWP).

Aspect 14: The method of Aspect 12, wherein the default rule specifies that the default beam comprises a fixed beam associated with a transmission configuration indicator (TCI) state with a lowest identifier in an active bandwidth part (BWP).

Aspect 15: The method of any one of Aspects 1-14, wherein the PDSCH is received using the default beam across the plurality of time periods when a time offset between the PDSCH and a physical downlink control channel (PDCCH) is equal to or less than a threshold amount of time.

Aspect 16: The method of Aspect 15, wherein the threshold amount of time is based on a capability of the UE.

Aspect 17: A method for wireless communications by a network entity, comprising: transmitting, to a user equipment (UE), configuration information; selecting a default beam based on the configuration information, wherein the default beam is selected for use across a plurality of time periods; and transmitting a physical downlink shared channel (PDSCH) using the default beam across the plurality of time periods.

Aspect 18: The method of Aspect 17, wherein the configuration information includes information identifying the selected default beam as a beam selected based on UE capability information.

Aspect 19: The method of any one of Aspects 17-18, wherein the configuration information identifies one or more rules for selecting the default beam.

Aspect 20: The method of Aspect 19, wherein the one or more rules comprise a rule for selecting the default beam based on whether the UE is operating in a first frequency band or a second frequency band.

Aspect 21: The method of Aspect 20, wherein the rule specifies that the default beam is selected based on a control resource set (CORESET) identifier of a latest monitored slot when the UE is operating in the first frequency band.

Aspect 22: The method of Aspect 20, wherein the rule specifies, when the UE is operating in the second frequency band, the default beam comprises a fixed beam associated with at least one of a transmission configuration indicator (TCI) state with a lowest identifier in an active bandwidth part (BWP) or a control resource set (CORESET) with a lowest identifier in the active BWP.

Aspect 23: The method of any one of Aspects 17-22, wherein the configuration information comprises an indication to select the default beam as a beam associated with a control resource set (CORESET) with a lowest identifier in a latest monitored slot until the UE receives another indication to use a fixed beam across slots.

Aspect 24: The method of any one of Aspects 17-23, wherein the configuration information includes one or more rules for selecting the default beam in response to a beam failure recovery (BFR) event.

Aspect 25: The method of Aspect 24, wherein the one or more rules specify that when a default beam prior to the BFR event is selected based on a transmission configuration indicator (TCI) state, the default beam is selected as a beam associated with a control resource set (CORESET) having a lowest identifier for a latest monitored slot or a beam associated with a CORESET having a lowest identifier in an active bandwidth part (BWP).

Aspect 26: The method of Aspect 24, wherein the one or more rules specify that when a default beam prior to the BFR event is fixed, the default beam is selected as a beam associated with a control resource set (CORESET) having a lowest identifier for a latest monitored slot until the UE receives an indication to use a fixed beam across slots.

Aspect 27: The method of any one of Aspects 17-26, further comprising: receiving, from the UE, signaling indicating a UE capability for dynamically changing one or more rules associated with the selection of the default beam.

Aspect 28: The method of any one of Aspects 17-27, further comprising: prior to the transmission of the configuration information, selecting an initial default beam based on a default rule.

Aspect 29: The method of Aspect 28, wherein the default rule specifies that the default beam comprises a fixed beam associated with a control resource set (CORESET) with a lowest identifier in an active bandwidth part (BWP).

Aspect 30: The method of Aspect 28, wherein the default rule specifies that the default beam comprises a fixed beam associated with a transmission configuration indicator (TCI) state with a lowest identifier in an active bandwidth part (BWP).

Aspect 31: The method of any one of Aspects 17-30, wherein the PDSCH is transmitted using the default beam across the plurality of time periods when a time offset between the PDSCH and a physical downlink control channel (PDCCH) is equal to or less than a threshold amount of time.

Aspect 32: The method of any one of Aspects 17-31, wherein the threshold amount of time is based on a capability of the UE.

Aspect 33: A user equipment (UE), comprising: a transceiver, a memory having instructions stored thereon, and at least one processor configured to execute the instructions for performing the operations of one or more of Aspects 1-16.

Aspect 34. A network entity, comprising: a transceiver, a memory having instructions stored thereon, and at least one processor configured to execute the instructions for performing the operations of one or more of Aspects 17-32.

Aspect 35: A user equipment (UE), comprising: means for performing the operations of one or more of the Aspects 1-16.

Aspect 36: A network entity, comprising: means for performing the operations of one or more of the Aspects 17-32.

Aspect 37: An apparatus for wireless communications by a user equipment (UE), comprising: an interface configured to obtain, from a network entity, configuration information; a memory having instructions stored thereon; and at least one processor configured to execute the instructions to cause the apparatus to select a default beam based on the configuration information, wherein the default beam is selected for use across a plurality of time periods and obtain a physical downlink shared channel (PDSCH) using the default beam across the plurality of time periods.

Aspect 38: An apparatus for wireless communications by a network entity, comprising: an interface configured to output, for transmission to a user equipment (UE), configuration information; a memory having instructions stored thereon; and at least one processor configured to execute the instructions to cause the apparatus to select a default beam based on the configuration information, wherein the default beam is selected for use across a plurality of time periods and initiate a transmission of a physical downlink shared channel (PDSCH) via the default beam across the plurality of time periods.

Aspect 39: A computer-readable medium for wireless communications comprising instructions executable by an apparatus to: obtain, from a network entity, configuration information; select a default beam based on the configuration information, wherein the default beam is selected for use across a plurality of time periods; and obtain a physical downlink shared channel (PDSCH) using the default beam across the plurality of time periods.

Aspect 40: A computer-readable medium for wireless communications comprising instructions executable by an apparatus to: output, for transmission to a user equipment (UE), configuration information; select a default beam based on the configuration information, wherein the default beam is selected for use across a plurality of time periods; and initiate a transmission of a physical downlink shared channel (PDSCH) via the default beam across the plurality of time periods.

Additional Considerations

The techniques described herein may be used for the wireless networks and radio technologies mentioned above as well as other wireless networks and radio technologies. For clarity, while aspects may be described herein using terminology commonly associated with 3G, 4G, or 5G wireless technologies, aspects of the present disclosure can be applied in other generation-based communication systems.

NR may utilize OFDM with a CP on the uplink and downlink and include support for half-duplex operation using time division duplexing (TDD). In NR, a subframe is still 1 ms, but the basic TTI is referred to as a slot. A subframe contains a variable number of slots (for example, 1, 2, 4, 8, 16, . . . slots) depending on the subcarrier spacing. The NR RB is 12 consecutive frequency subcarriers. NR may support a base subcarrier spacing of 15 KHz and other subcarrier spacing may be defined with respect to the base subcarrier spacing, for example, 30 kHz, 60 kHz, 120 kHz, 240 kHz, etc. The symbol and slot lengths scale with the subcarrier spacing. The CP length also depends on the subcarrier spacing. Beamforming may be supported and beam direction may be dynamically configured. MIMO transmissions with precoding may also be supported. In some examples, MIMO configurations in the DL may support up to 8 transmit antennas with multi-layer DL transmissions up to 8 streams and up to 2 streams per UE. In some examples, multi-layer transmissions with up to 2 streams per UE may be supported. Aggregation of multiple cells may be supported with up to 8 serving cells.

As used herein, the term “determining” may encompass one or more of a wide variety of actions. For example, “determining” may include calculating, computing, processing, deriving, investigating, looking up (for example, looking up in a table, a database or another data structure), assuming and the like. Also, “determining” may include receiving (for example, receiving information), accessing (for example, accessing data in a memory) and the like. Also, “determining” may include resolving, selecting, choosing, establishing and the like.

As used herein, a phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination with multiples of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c). The previous description is provided to enable any person skilled in the art to practice the various aspects described herein.

The various operations of methods described above may be performed by any suitable means capable of performing the corresponding functions. The means may include various hardware and/or software component(s) and/or module(s), including, but not limited to a circuit, an application specific integrated circuit (ASIC), or processor. For example, processors266,258,264, and/or controller/processor280of the UE120and/or processors220,230,238, and/or controller/processor240of the BS110shown inFIG. 2may be configured to perform operations400ofFIG. 4and operations500ofFIG. 5.

Means for receiving may include a receiver such as antenna(s) and/or receive processor(s) illustrated inFIG. 2. Means for transmitting may include a transmitter such as antenna(s) and/or transmit processor(s) illustrated inFIG. 2. Means for indicating and means for selecting may include a processing system, which may include one or more processors, such as processors266,258,264, and/or controller/processor280of the UE120and/or processors220,230,238, and/or controller/processor240of the BS110shown inFIG. 2.

In some cases, rather than actually transmitting a frame a device may have an interface to output a frame for transmission (a means for outputting). For example, a processor may output a frame, via a bus interface, to a radio frequency (RF) front end for transmission. Similarly, rather than actually receiving a frame, a device may have an interface to obtain a frame received from another device (a means for obtaining). For example, a processor may obtain (or receive) a frame, via a bus interface, from an RF front end for reception.