Abstract: Methods, systems, and devices for wireless communication are described. A first wireless device may receive a clear to send signal based precoded based at least in part on a receive filter at a second wireless device. The first wireless device may calculate a transmit precoder based at least in part on the clear to send signal. For example, the first wireless device may calculate a whitening filter and a second filter based at least in part on the clear to send signal. The first wireless device may transmit a request to send signal precoded by the transmit precoder to initiate communications with a third wireless device without significantly interfering with ongoing communications at the second wireless device.

Abstract: Over-the-air phase synchronization for reciprocity-based coordinated multipoint (CoMP) joint transmission is discussed. The base stations of the CoMP group and served user equipment (UEs) transmit phase synchronization reference signals (PSRS). The receiving nodes compute wideband co-phasing values representing the phase difference between pairs of the PSRS over each tone of a whole spectrum band, and slope values based on the per-tone co-phasing values. The UEs feedback the wideband downlink co-phasing value and the downlink slope value. The base stations of the CoMP group determine a phase compensation based on the differences between the slope value calculated by the base station and the slope value reported by the UE, and based on the differences between the wideband co-phasing value calculated by the base station and the wideband co-phasing value reported by the UE. The base station uses the phase compensation to adjust communications by the base stations in the CoMP group.

Abstract: Spatial listen before talk (LBT) with broadcasting or multicasting reception is disclosed. Aspects of the disclosure provide for managing spatial LBT transmissions between broadcast communication nodes and neighboring cells. In one aspect, the broadcast transmitter transmits a preamble that identifies the broadcast transmission durations and the non-broadcast durations in the upcoming transmit opportunity. The potential interferer would read the preamble and yield any transmissions during the broadcast durations. Additional aspects provide for a periodic broadcast clear-to-send (CTS) signal transmitted by the broadcast receivers. The interferer may use the broadcast CTS to perform spatial LBT during the broadcast durations. Further aspects allow the broadcast receivers to determine when potential interferers would cause interference above a threshold. In such circumstances, the broadcast receivers would send the CTS to allow the interferer to perform spatial LBT during the broadcast durations.

Abstract: A network may use enhanced sounding reference signal (SRS) transmission techniques to support reference signal transmissions over shared spectrum. For example, a wireless device may receive an uplink grant and an indicator. The uplink grant may include an uplink resource allocation to the wireless device and the indicator may alert the device of a forthcoming reference signal transmission. The wireless device may use the uplink grant and the indicator to determine a reference signal transmission period relative to the resources assigned in the uplink grant. For example, the wireless device may determine that the reference signal transmission period is prior to, during, or subsequent to the uplink transmission period. In some cases, a wireless device may be aperiodically or periodically scheduled for reference signal transmissions.

Abstract: Consideration of contention windows with spatial listen before talk (LBT) operations is discussed. In multiple input, multiple output (MIMO) transmission operations over a shared transmission medium, use of spatial LBT transmissions may be implemented with fairness options and parameters influenced by a condition of the MIMO transmitter, such conditions as the level of MIMO capability or the enablement of polite spatial LBT nulling transmissions. When a MIMO transmitter identifies data for transmission, it may determine a configuration of the medium access contention operation, synchronous or asynchronous content, based on the condition of the MIMO transmitter. The MIMO transmitter may then transmit the data either using spatial LBT transmission or not according to the configuration of the medium access contention operation.

Abstract: Over-the-air phase synchronization for reciprocity-based coordinated multipoint (CoMP) joint transmission is discussed. The base stations of the CoMP group and served user equipment (UEs) each transmit phase synchronization reference signals (PSRS). The receiving nodes will compute co-phasing values representing the phase difference between pairs of the PSRS. For example, the difference between two downlink PSRS computed at the UE for a downlink co-phasing value, and the difference between a single PSRS received at two base stations computed at the base station for an uplink co-phasing value. The base stations of the CoMP group may determine a phase compensation by computing the differences between the uplink and downlink co-phasing values and use that phase compensation to adjust communications by the base stations in the CoMP group. In other aspects, the computed co-phasing values may be used to modulate each nodes transmission of its respective PSRS.

Abstract: Over-the-air (OTA) phase synchronization for reciprocity-based coordinated multipoint (CoMP) joint transmission is disclosed. Phase synchronization reference signals (PSRS) are transmitted within a CoMP operation that can be used to determine the phase drifts of the transmit and receive chains of the base stations. These phase drifts can then be used to obtain a relative phase drift between the uplink and downlink channels. When estimating the uplink channel from the sounding reference signals (SRS), the relative phase drift may be applied to estimate the downlink channel as well. The OTA phase synchronization may be performed with a user equipment (UE)-assisted or inter-base station procedures.

Abstract: Phase compensation in a new radio (NR) coordinated multipoint (CoMP) environment is discussed. A base station may synchronize the phase between one or more additional base stations in a CoMP group serving one or more user equipments (UEs). A base station estimates an uplink channel based on a sounding reference signal (SRS) received from a given UE. The base station transmits a phase synchronization reference signal (PSRS) modulated using the uplink channel estimate. The UE can measure the phase and/or timing drift from the PSRS and then will report the compensation information for the phase and timing drift back to the base station. The base station may then use the compensation information to adjust transmission characteristics for the CoMP group.

Abstract: Over-the-air (OTA) phase synchronization for reciprocity-based coordinated multipoint (CoMP) joint transmission is disclosed. Phase synchronization reference signals (PSRS) are transmitted within a CoMP operation that can be used to determine the phase drifts of the transmit and receive chains of the base stations. These phase drifts can then be used to obtain a relative phase drift between the uplink and downlink channels. When estimating the uplink channel from the sounding reference signals (SRS), the relative phase drift may be applied to estimate the downlink channel as well. The OTA phase synchronization may be performed with a user equipment (UE)-assisted or inter-base station procedures.

Abstract: Aspects of the present disclosure describe receiving an indication of a covariance matrix from an access point, receiving downlink signaling from the access point, deriving, based at least in part on the covariance matrix or the downlink signaling, one or more precoders for uplink communications over an uplink channel, and indicating, based at least in part on the one or more precoders, uplink channel feedback to the access point.

Abstract: Phase compensation in a new radio (NR) shared spectrum (NR-SS) coordinated multipoint (CoMP) environment is discussed. A base station may synchronize the phase between one or more additional base stations in a coordinated multipoint (CoMP) group serving one or more user equipments (UEs). This first synchronizing is performed prior to a current transmission opportunity between the CoMP group and the UEs. During transmission, a UE will sent a phase compensation reference signal (PCRS) to help with adjusting a phase drift that exceeds a predetermined threshold. The PCRS may be triggered by a signal from the base station or may be sent routinely by the UE. The UEs will transmit PCRS after each subframe, which the base stations use to adjust the phase.

Abstract: Systems and methods herein determine whether an uplink RACH request and/or an uplink autonomous message will be sent using Discrete Fourier Transform-Spread-Orthogonal Frequency Division Multiplexing (DFT-S-OFDM), Cyclic Prefix Orthogonal Frequency Division Multiplexing (CP-OFDM), or another waveform. The determinations may be based on carrier frequencies, path loss measurements, preconfigurations, and/or more. Further, the systems and methods may send the uplink using time and/or frequency resources that correspond to the DFT-S-OFMD waveform, CP-OFDM waveform, or other waveform. Other aspects, embodiments, and features are also claimed and described.

Abstract: Various aspects described herein relate to techniques for signaling and channel design in wireless communications systems (e.g., a 5G NR system). In an aspect, a method includes identifying a direct current (DC) subcarrier of a synchronization bandwidth, determining whether a synchronization signal transmits on, punctures, or rate matches around the DC subcarrier, and performing synchronization channel processing based on the determination.

Abstract: A method of wireless communication may include transmitting an uplink slot with a first control region, a second control region, and (e.g., optionally) a data region. Each region may include time resources and frequency resources. Transmitting the uplink slot may include transmitting the first control region in an earlier part of the uplink slot and transmitting the second control region (e.g., and the data region) in a later part of the uplink slot. The first control region may include time-critical control information and the second control region may include non-time-critical control information. A receiver receiving the uplink slot may receive the first control region before receiving the data region and the second control region.

Abstract: Techniques are described for wireless communication. One method includes receiving, in a downlink portion of a transmission structure on a shared radio frequency spectrum band, an uplink grant for an uplink data portion of the transmission structure. The transmission structure includes the downlink portion, followed by and time domain multiplexed with an uplink control portion, followed by and time domain multiplexed with the uplink data portion. The method also includes retaining access to the shared radio frequency spectrum band by transmitting an unscheduled transmission during the uplink control portion of the transmission structure.

Abstract: Various aspects described herein relate to small cyclic delay diversity (SCDD) operation used in a wireless communication system (e.g., 5G New Radio). A method, a computer-readable medium, and an apparatus are provided. In an aspect, the method, computer-readable medium, or apparatus operates to identify a type of information for transmission, identify a rank associated with the type of information, and perform an SCDD precoding operation based at least in part on the identified type of information or the rank.

Abstract: Blind interference cancellation is described for wireless networks in which a subject base station or cancellation apparatus obtains semi-static information for at least one of its neighboring cells. The base station measures the noise level of each of the neighboring cells based on samples it takes of uplink transmissions in each of the neighboring cells. The neighboring cells are then ranked for interference cancellation based on their relative noise levels. The base station performs discontinuous transmission (DTX) detection to identify at least one interfering user equipment (UE) in the neighboring cell and cancels interference attributable to those identified interfering UEs. The DTX detection and cancellation are then repeated for the remaining neighboring cells in the order they are ranked.

Abstract: Devices, systems, methods and/or computer program products are provided to facilitate coordinated multipoint transmission and reception of communications in a wireless network. In some scenarios, different set of resources are allocated for uplink transmissions of multiple user equipment. In other scenarios collision avoidance and/or multiplexing techniques are used to enable reception and decoding of multiple uplink transmissions on the same or overlapping resources at the same time. This Abstract is provided for the sole purpose of complying with the Abstract requirement rules that allow a reader to quickly ascertain the disclosed subject matter. Therefore, it is to be understood that it should not be used to interpret or limit the scope or the meaning of the claims.

Abstract: A base station may provide both an uplink grant and a downlink grant in a same transmission time interval (TTI), and may provide an indication in the uplink grant that the TTI includes the downlink grant. A user equipment (UE) that receives the uplink grant may provide feedback using identified feedback resources in an uplink shared channel, and other uplink transmissions may be rate matched around the feedback resources in the uplink shared channel. A base station receiving the feedback may monitor the feedback resources to determine whether the downlink grant or one or more of the downlink transmissions were successfully received at the UE. A base station, in some examples, may monitor different sets of resources to determine whether certain of the uplink grant, downlink grant, downlink transmissions associated with the downlink grant, or any combinations thereof, have been successfully received at the UE.

Abstract: Methods, systems, and devices for wireless communication are described. A base station may multiplex reference signal (RS) transmissions for different antenna ports over a set of resource elements using a code division multiplexing (CDM) group spreading in a time dimension and a frequency dimension. The base station may transmit the RS transmissions over the set of resource elements based at least in part on the multiplexing to a user equipment (UE). The UE may demultiplex the RS transmissions based at least in part on a CDM group and may select at least one of the time dimension or the frequency dimension over which to demultiplex the RS transmissions based on a determination or other information.