Abstract: Methods, systems, and devices for wireless communications are described. In some systems, a user equipment (UE) may perform a random access (RACH) procedure based on a selected synchronization signal block (SSB). During this RACH procedure, a base station may transmit physical downlink control channel (PDCCH) messages for UE RACH message handling. To receive PDCCH signaling for RACH Messages 2, 3, or 4 (Msg 2/3/4), the UE may identify a set of time resources used by the base station for transmitting SSBs that are not quasi-co-located (QCL) with the selected SSB. The UE may identify a Msg 2/3/4 search space that does not overlap with this identified set of resources, and may monitor this identified search space. The search space may correspond to a modified remaining minimum system information (RMSI) search space indicated by the base station, or a valid RMSI search space not indicated by the base station.

Abstract: Systems, methods, and apparatuses for performing a beam recovery procedure using a second CC are disclosed. A UE may perform a beam recovery procedure using two component carriers (CCs): for example, first component carrier may be a beam formed millimeter wave (MMW) carrier having a beam recovery procedure and second component carrier may be an assisting carrier such as a sub-6 GHz carrier or a different MMW carrier. In a first example, a UE may trigger beam recovery for first component carrier (on second component carrier), generate a beam measurement report, and transmit the beam report on resources allocated for uplink transmission on second component carrier. In a second example, a new scheduling request (SR) may be defined on first component carrier for second component carrier beam recovery. In a third example, RACH resources or procedures on second component carrier may be used to perform the beam recovery for first component carrier.

Abstract: Certain aspects of the present disclosure provide techniques for beam refinement. A base station provides information regarding what transmit beams are used to transmit different reference signal (RS) resources. In some cases, the information indicates whether a same transmit beam is used to transmit a set of RS resources (e.g., symbol, sub-symbol, or frequency resources) or whether different transmit beams are used to transmit the set of RS resources.

Abstract: Methods and apparatuses for estimating channel state information in advanced multi input multi output (MIMO) antenna systems for cellular communications. A method of operating a base station (BS) includes: generating first configuration information including a set of sounding reference signal (SRS) resources each of which is associated with an sounding reference signal (SRS)-path loss reference signal; transmitting, to a user equipment (UE), the first configuration information; receiving an SRS based on the first configuration information; selecting, based on the SRS and the first configuration information, a subset of the set of SRS resources; and generating second configuration information including the subset of the set of SRS resources.

Abstract: Methods, systems, and devices for wireless communications are described for antenna selection and reporting for multiple-input multiple-output (MIMO) communications. One or more grouping parameters may be provided to a wireless node, which may indicate a subset of antennas that are to be used for MIMO communications, may indicate one or more target nodes for MIMO communications, or combinations thereof. The wireless node may measure one or more channel parameters based on the grouping parameters and determine one or more antenna subsets or target nodes that meet MIMO communication parameters (e.g., an antenna group or target node that will support a certain rank of MIMO communications). The wireless node may report an indication of the identified antenna subsets or target nodes to a control entity for scheduling of MIMO communications.

Abstract: Methods, systems, and devices for wireless communications are described. A node (e.g., a base station or network entity) may identify a signal that provides an indication of a location of a contention free random access channel (CFRA) resource within a time region and an indication of a timing pattern for the CFRA resource, the timing pattern associated with a pattern of subsequent instances of the time region in which the CFRA resource is repeated, wherein the CFRA resource is not a fully overlapping resource with respect to a contention based random access (CBRA) resource. The node may convey the signal to one or more user equipment (UE) to indicate the location and the timing pattern.

Abstract: An apparatus may determine whether to indicate a beam failure recovery request to a base station using a contention-free RACH procedure with a dedicated preamble when the UE is timing unsynchronized with the base station. The apparatus may perform, when the apparatus is timing unsynchronized with the base station, the contention-free RACH procedure with the dedicated preamble to indicate the beam failure recovery request when the beam failure recovery request is determined to be indicated to the base station using the contention-free RACH procedure with the dedicated preamble. The apparatus may perform, when the apparatus is timing unsynchronized with the base station, a contention-based RACH procedure to indicate the beam failure recovery request when the beam failure recovery request is undetermined to be sent to the base station using the contention-free RACH procedure with the dedicated preamble.

Abstract: Certain aspects of the present disclosure provide techniques for beam refinement. A base station provides information regarding what transmit beams are used to transmit different reference signal (RS) resources. In some cases, the information indicates whether a same transmit beam is used to transmit a set of RS resources (e.g., symbol, sub-symbol, or frequency resources) or whether different transmit beams are used to transmit the set of RS resources.

Abstract: Techniques are described for wireless communication. In one method, a user equipment (UE) receives a timing synchronization signal (TSS) and a physical broadcast channel (PBCH), with the TSS based at least in part on a timing of the TSS within a broadcast channel transmission time interval (BCH TTI); determines the timing of the TSS within the BCH TTI; and demodulates the PBCH based at least in part on the TSS. In another method, a base station allocates resources for a TSS and a PBCH within a BCH TTI; determines the TSS based at least in part on a timing of the TSS within the BCH TTI; and transmits, on the resources allocated for the TSS and the PBCH, the TSS and the PBCH, with the TSS transmitted as a demodulation reference signal (DMRS) for the PBCH on at least one port used to transmit the TSS and the PBCH.

Abstract: A method, an apparatus, and a computer-readable medium for wireless communication are provided. In some aspects, a base station may send a beam modification command that indicates a set of transmit beam indexes corresponding to a set of transmit beams of a base station, and each transmit beam index of the set of transmit beam indexes may indicate at least a transmit direction for transmitting a transmit beam by the base station. The base station may send, in association with the beam modification command, a reference signal using at least one transmit beam of the set of transmit beams, where a first portion of the reference signal is sent in a first set of symbols and a second portion of the reference signal is received in a second set of symbols.

Abstract: Methods, systems, and devices for wireless communication are described. A network device, such as a base station, may transmit a request message to a user equipment (UE). The request message may include a request for the UE to transmit a set of sounding reference signals (SRSs). The set of SRSs may include two (or more) beamformed signals. The network device may receive the set of SRSs according to the request message. The network device may identify, based on a co-phasing parameter associated with the two (or more) beamformed signals, an antenna port precoder configuration to use for communicating with the UE.

Abstract: Methods, systems, and devices for wireless communication are described. In some wireless systems, a base station may configure a user equipment (UE) for random access (RACH) message transmission in dedicated RACH resources during, for example, a handover process. The contention-free random access (CFRA) resources may allow the UE to transmit RACH messages at a higher transmission power than contention-based random access (CBRA) resources. The base station may indicate, to the UE, RACH transmission parameters for CFRA that are different than parameters for CBRA. These parameters may include configuration information, frequency division multiplexing information, RACH retransmission parameters, target received power, response window length, etc. The UE may use the indicated RACH transmission parameters to transmit a RACH message to the base station. The base station may respond with a RACH response message, and the base station and UE may synchronize upon completion of the RACH procedure.

Abstract: Certain aspects of the present disclosure relate to methods and apparatus for radio link monitoring reference signal (RLM-RS) determination using communications systems operating according to new radio (NR) technologies. For example, a method for wireless communications from a UE generally includes determining resources to monitor for radio link monitoring (RLM) prior to being configured with resources to monitor for RLM after establishing a radio resource control (RRC) connection with a network, and performing RLM based on the determined resources.

Abstract: Methods, systems, and devices for wireless communications are described that provide for signaling and switching of beam pair links (BPLs) for directional transmission beams between a base station and a user equipment (UE). A threshold value may be determined, which corresponds to an amount of time for a UE to receive and decode control information, and apply a different BPL than a current BPL that that is in use. The UE may maintain a BPL for data, which is used during data transmission time intervals (TTIs) until an indication is received to change the BPL for data. The UE and the base station may determine to change between BPLs based at least in part on the threshold value and a scheduling offset between a control channel transmission that allocates resources for a data TTI and a start of the data TTI.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a first wireless node may receive, from a second wireless node, a round-trip time timing advance indicator, wherein the round-trip time timing advance indicator is different from a timing advance indicator used for an uplink transmission timing advance message. In some aspects, the first wireless node may synchronize a timing configuration of the first wireless node to at least one of the second wireless node or a third wireless node based at least in part on the round-trip time timing advance indicator. Numerous other aspects are provided.

Abstract: A first apparatus may communicate with a user equipment (UE) through an active beam. The first apparatus may transmit, to the UE, information indicating a periodicity at which control information is to be communicated on a control channel through a control-information beam. The first apparatus may communicate, with the UE, the control information on the control channel through the control-information beam at the periodicity. Further, the first apparatus may receive a request to change the active beam, which may indicate a beam index corresponding to a second beam, and the first apparatus may change the active beam to the second beam corresponding to the beam index indicated by the request.

Abstract: Methods, systems, and devices for wireless communication are described. In some wireless systems, a base station may configure a user equipment (UE) for random access (RACH) message transmission in dedicated RACH resources during, for example, a handover process. The contention-free random access (CFRA) resources may allow the UE to transmit RACH messages at a higher transmission power than contention-based random access (CBRA) resources. The base station may indicate, to the UE, RACH transmission parameters for CFRA that are different than parameters for CBRA. These parameters may include configuration information, frequency division multiplexing information, RACH retransmission parameters, target received power, response window length, etc. The UE may use the indicated RACH transmission parameters to transmit a RACH message to the base station. The base station may respond with a RACH response message, and the base station and UE may synchronize upon completion of the RACH procedure.

Abstract: Methods, systems, and devices for wireless communication are described. A network device, such as a base station, may transmit a request message to a user equipment (UE). The request message may include a request for the UE to transmit a set of sounding reference signals (SRSs). The set of SRSs may include two (or more) beamformed signals. The network device may receive the set of SRSs according to the request message. The network device may identify, based on a co-phasing parameter associated with the two (or more) beamformed signals, an antenna port precoder configuration to use for communicating with the UE.

Abstract: Certain aspects of the present disclosure provide techniques for multiplexing initial access transmissions with data and/or control transmissions. For example, the techniques include a method for wireless communication by a first base station (BS). The method includes communicating, in a first time interval, with at least a first user equipment (UE), via directional transmissions using a first set of frequency resources, and participating in at least one of an access or management procedure, during the first time interval, via directional transmissions using a second set of frequency resources.

Abstract: Disclosed are techniques for transmitting reference signals (RS) for positioning. A method comprises transmitting or providing an instruction to transmit a first set of RS to a user equipment (UE) in accordance with a first set of RS transmission parameters, receiving a report containing information indicating whether a measurement performed by the UE is limited by a signal-to-noise ratio (SNR) of the first set of RS or a bandwidth of the first set of RS, determining a second set of RS transmission parameters using the received report, wherein the second set of RS transmission parameters is different from the first set of RS transmission parameters, and transmitting a second set of RS to the UE in accordance with the second set of RS transmission parameters, or providing the second set of RS transmission parameters to a base station.