Abstract: Methods, systems, and devices for wireless communications are described. In a wireless communications system, a user equipment (UE) may be configured to use intra-message antenna selection diversity (ASD). The UE may transmit a first portion of a scheduled message within a time interval using a first antenna element of the UE based on an intra-message antenna diversity configuration. The intra-message antenna diversity configuration may indicate a set of antennas available for transmission of the scheduled message. In some cases, the UE may transmit, within the same time interval, at least a portion of the scheduled message using at least a second antenna element of the UE that is different from the first antenna element. In some cases, a receiving UE may decode the first portion and the second portion of the scheduled message based on the intra-message antenna diversity configuration.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive, from a transmitter, a reference signal block provided based at least in part on an orthogonal frequency division multiplexing (OFDM) waveform. The UE may perform an estimation operation based at least in part on the reference signal block. The UE may receive a data transmission via a single carrier waveform based at least in part on the estimation operation. Numerous other aspects are provided.

Abstract: Aspects described herein relate to configuring a search space size for a demodulator to use in generating log likelihood ratios (LLRs) in demodulating received signals. In an aspect, an indication of a search space size for a demodulator to use in generating LLRs can be received from a base station, and a demodulation of one or more signals received in wireless communication can be performed by a node using the demodulator and based on the search space size. In another aspect, a search space size for the demodulator of the node to use in generating log likelihood ratios (LLRs) can be determined based on one or more signals transmitted by the node, and an indication of a search space size can be transmitted to the node.

Abstract: Apparatus, methods, and computer program products for improving precoding downlink signaling are provided. An example method may include determining one or more noise covariance parameters for a noise covariance report, the noise covariance parameters being associated with a noise covariance matrix for whitening. The example method further may include transmitting, to a base station, the noise covariance report including the one or more noise covariance parameters or a noise whitening matrix for the whitening, the noise covariance report being transmitted based on a transmission periodicity of one or more slots.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive, in a slot, a preamble provided based at least in part on an orthogonal frequency division multiplexing (OFDM) waveform. The UE may perform an estimation operation based at least in part on the preamble. The UE may receive, in the slot, a data transmission via a single carrier time-domain waveform based at least in part on the estimation operation. Numerous other aspects are provided.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may transmit, to a base station, a report that indicates a phase tracking reference signal (PTRS) density for a PTRS. The UE may receive, from the base station via a downlink shared channel, the PTRS in accordance with the PTRS density based at least in part on the report. Numerous other aspects are described.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive, from a base station via a downlink shared channel, a phase tracking reference signal (PTRS) in accordance with a PTRS density based at least in part on a modulation and coding scheme (MCS) and a signal-to-noise ratio (SNR) associated with the UE. The UE may estimate a phase noise associated with the PTRS based at least in part on the PTRS density. Numerous other aspects are described.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive, from a base station, a phase tracking reference signal. The phase tracking reference signal is transmitted using a single carrier waveform and encoded within a time domain. Accordingly, the UE may decode, from the base station, a message, based at least in part on the phase tracking reference signal. Numerous other aspects are provided.

Abstract: Methods, systems, and devices for wireless communications are described. A base station may transmit, to a user equipment (UE), a first demodulation reference signal for each of one or more sub-bands and configured in accordance with a first one or more demodulation reference signal configurations. The UE may select a second demodulation reference signal configuration from a respective set of second demodulation reference signal configurations for each of the one or more sub-bands and may transmit an indication of the second demodulation reference signal configuration for each of the one or more sub-bands. The base station may receive the indication and may transmit, to the UE, a second demodulation reference signal for each of the one or more sub-bands and configured in accordance with the second demodulation reference signal configuration for each of the one or more sub-bands.

Abstract: Methods, systems, and devices for wireless communications are described. In some systems, a user equipment (UE) may determine a set of groups of layers relating to a set of transport blocks (TBs) or a set of code division multiplexing (CDM) groups. The UE may group the layers such that the layers in each group have a minimal difference in signal-to-interference-plus-noise ratio (SINR) between the layers. The UE may select a different demodulation reference signal (DMRS) configuration for each of the set of groups of layers based on maximizing a communication efficiency metric for each group of layers. The UE may transmit an indication of the selected DMRS configurations for each group of layers to a base station via a field in a report. The base station may accordingly determine a DMRS configuration for each group of layers based on the DMRS configurations indicated by the UE.

Abstract: Methods, systems, and devices for wireless communications are described. A user equipment (UE) may receive pilot signaling associated with inphase and quadrature (IQ) mismatch estimation for a set of antennas of a base station. The UE may measure pilot signals for each of the set of antennas based on a pilot signal pattern of the pilot signaling, and calculate an estimation of an IQ mismatch for each antenna of the set of antennas of the base station based on measuring the pilot signals. The base station may receive, from the UE, a report including an indication of the estimation of the IQ mismatch for each antenna of the set of antennas of the base station based on the pilot signals.

Abstract: Methods, systems, and devices for wireless communications are described. A transmitting device (e.g., a user equipment (UE) or base station) may reduce a peak to average power ratio (PAPR) by clipping signals transmitted to a receiving device according to a clipping level. The receiving device may receive, from the transmitting device, an indication of the clipping level associated with a reference signal. The receiving device may receive the reference signal and identify distortions based on the clipping level. The receiving device may iteratively reconstruct peaks of the clipped reference signal until the receiving device is able to obtain accurate pilot symbols for use in channel estimation. The techniques described herein may enable receiving devices to improve efficiency and reliability of communications by improving channel estimation, which may increase the probability of successfully decoding transmitted information.

Abstract: Methods, systems, and devices for wireless communications are described. A user equipment (UE) may receive, within a subframe, a plurality of sidelink control channel signals providing scheduling information for a plurality of sidelink shared channel signals that are also received within the subframe. The UE may determine to use one or more of the plurality of sidelink control channel signals as pilot signals for decoding the plurality of sidelink shared channel signals. The UE may decode the plurality of sidelink shared channel signals based at least in part on the plurality of sidelink control channel signals as pilot signals.

Abstract: A method of receiving messages by a communication terminal. The method includes receiving symbols of a frame of a transmitted encoded message, and decoding the frame based on fewer received symbols than the number of symbols in the frame.