Abstract: Methods, systems, and devices for wireless communications are described for optimizing index modulated (IM) communications between a user equipment (UE) and a base station. The UE may identify a quantity of subcarriers for IM communications and transmit a message including an indication of the quantity of subcarriers to the base station. In some examples, the UE may transmit an indication of one or more subcarriers to exclude from IM communications. The base station may receive the indication of the quantity of subcarriers and/or the indication of the blacklisted subcarrier(s) and may determine a number of active subcarriers to be used based on at least the indication of the quantity of subcarriers. The base station may transmit an indication of the number of active subcarriers to the UE. The UE may process one or more received IM downlink signals based on the quantity of subcarriers.

Abstract: Certain aspects of the present disclosure provide techniques for wireless communication by a first wireless device. The first wireless device may participate in a beam forming procedure with a second wireless device to evaluate a plurality of transmit (TX) and receive (RX) beam pairs. The first wireless device may select one of the TX and RX beam pairs based on the evaluation. The first wireless device may determine at least one cryptographic key based on channel parameters associated with a selected one of the TX and RX beam pairs. The first wireless device may use the at least one cryptographic key for communications with the second wireless device.

Abstract: Methods, systems, and devices for wireless communication are described for one or more aspects of dynamically configuring an analog-to-digital converter (ADC). A user equipment (UE) may determine a set of supported ADC resolution sizes including one or more dynamically configurable bit quantities. The UE may transmit a capability message including an indication of the set of ADC resolution sizes to a base station. The UE may indicate, to the base station, a power consumption factor or a table of signal-to-quantization noise ratios (SQNR) per bit quantity supported by the UE's ADC. In some cases, the base station may enable, based on the set of ADC resolution sizes, clipping of a power amplifier and one or more associated precoding parameters, and may indicate the precoding parameters to the UE. The UE may select an ADC resolution size for processing received messages.

Abstract: Aspects relate to analog-to-digital conversion of an analog signal. The resolution (number of bits) and/or the quantization levels of the analog-to-digital conversion may be configurable. A device may configure its analog-to-digital conversion parameters. For example, a first device may reduce the number of bits for its analog-to-digital converter to reduce power consumption. In this case, the first device may transmit an indication of selected analog-to-digital conversion parameters to a second device that will transmit to the first device. In this way, the second device may take appropriate action, if needed. A device may request another device to use certain analog-to-digital conversion parameters. For example, a first device may determine that a second device should use a larger number of bits for its analog-to-digital conversion process to improve the quality of the communication between the first and second devices.

Abstract: Methods, systems, and devices for wireless communication are described. A transmitting device may determine reconstruction information for a time-domain signal and may transmit the reconstruction information with the time-domain signal to a receiving device. The transmitting device may generate the reconstruction information based on estimates of how the receiving device may process the time-domain signal. For example, the transmitting device may apply a channel estimate to samples of the time-domain signal, and further perform clipping and quantization of the samples based on an estimated dynamic analog-to-digital converter (ADC) resolution of the receiving device. The transmitting device may generate the reconstruction information (e.g., using machine learning or other techniques) based on samples having the channel estimate applied and the clipped and quantized samples.

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: This disclosure presents an orbital angular momentum (OAM) antenna that includes a plurality of concentric antenna arrays, each antenna array corresponding to a different respective OAM order and being comprised of a different respective set of antenna elements arranged at a different respective radius. The OAM antenna also includes a plurality of phase shifters, each phase shifter corresponding to a different respective antenna array of the plurality of concentric antenna arrays. Each phase shifter is configured to trigger the respective set of antenna elements of a corresponding antenna array to generate a respective OAM beam. According to aspects of the disclosure, each OAM beam generated by a respective antenna array has a same divergence angle as the other OAM beams generated by the other respective antenna arrays of the plurality of concentric antenna arrays.

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: Methods, systems, and devices for wireless communications are described. The method may include an interference estimation procedure that measures interference from radio access technologies (RATs) different from cellular vehicle to everything (CV2X) on the CV2X network at a user equipment (UE). A UE may record measurements of interference on the CV2X network when no CV2X signal is present during the last symbol of a subframe. Then, the UE may estimate the noise plus interference measured during the empty symbol to improve noise plus interference whitening when decoding a subframe.

Abstract: Methods, systems, and devices for wireless communications are described. A user equipment (UE) may transmit, to a base station, a capability message indicating a capability supporting network-side phase noise compensation. The UE may transmit, to the base station, phase tracking reference signals based on transmitting the capability message. In an example, the phase tracking reference signals may include a UE phase noise component which may be associated with a local oscillator of the UE. The UE may receive, from the base station, a compensated downlink transmission that is compensated based on the UE phase noise component. In generating the compensated downlink transmission, the base station may apply a multiplication factor associated with the estimated UE phase noise component to the compensated downlink transmission.

Abstract: Methods, systems, and devices for wireless communications are described for reducing overhead associated with a cyclic prefix (CP) by supporting dynamic determination of a CP length. For example, a user equipment (UE) may establish a wireless connection with a base station by receiving initial communications according to a numerology and a first CP configuration associated with a first CP length. The UE may determine a second CP length after establishing the wireless connection and may transmit an indication to the base station, indicating the second CP length. The base station may receive the indication and may transmit downlink signals according to a second CP configuration associated with the second CP length. The initial communications and the downlink signals may be associated with a same numerology or subcarrier spacing.

Abstract: Methods related to wireless communication systems and the transmission of code blocks on such systems are provided. A wireless communication device interleaves a plurality of code block segments in time and frequency. The segments are interleaved by mapping a first code block segment of the plurality of code block segments to a first resource located at a first time and a first frequency, wherein the first code block segment is associated with a first code block, and mapping a second code block segment of the plurality of code block segments to a second resource based on at least one of the first time or the first frequency of the first resource and a code block proximity parameter, wherein the second code block segment is associated with a second code block different from the first code block. The device then transmits the plurality of interleaved code block segments. Other features are also claimed and described.

Abstract: Methods, systems, and devices for wireless communications are described. A base station may transmit, to each user equipment (UE) of a set of UEs, a different respective set of one or more training parameters for a digital pre-distortion procedure. Some or all of the UEs may determine one or more respective training values based on the one or more training parameters, where the training values from the UEs support the base station computing a set of non-linearity coefficients for the digital pre-distortion procedure. The base station thus may receive training parameters from some or all of the UEs and determine the set of non-linearity coefficients based thereon. The base station use the non-linearity coefficients to perform the digital pre-distortion procedure for one or more downlink transmissions, to one or more UEs of the group of UEs used for training, or to one or more other UEs.

Abstract: Certain aspects of the present disclosure provide techniques for over-the-air digital pre-distortion (DPD) kernel function selection. A method that may be performed by a user equipment (UE) includes transmitting capability information to a base station (BS), indicating a capability of the UE for performing digital pre-distortion (DPD) training, receiving, based on the capability information, a request from the BS to perform the DPD training, performing, based on the received request, the DPD training, wherein performing the DPD training includes: receiving one or more reference signals (RSs) and selecting, based on the one or more RSs, an ordered set of kernel functions. Additionally, the method may include transmitting feedback information to the BS indicating the ordered set of kernel functions.

Abstract: Methods, systems, and devices for wireless communications are described. A wireless communications system may support inter-band inter-cell interference coordination (ICIC) measurement and capability reporting. For example, a user equipment (UE) may transmit, to a base station, a capability message indicating its ability to use low power signal processing in the absence of inter-band interference and its ability to report values associated with inter-band interference measurement. In addition, the UE may transmit, to the base station, a measurement report indicating values associated with inter-band interference and in response, the base station may update communications with the UE to avoid inter-band interference or the base station may coordinate with other base stations to avoid inter-band interference.

Abstract: Techniques for wireless communications are described. A demodulation reference signal generated using user information and a noncoherent modulation technique may be communicated between wireless devices. A data sequence may be extracted from the demodulation reference signal based on demodulating the demodulation reference signal using the noncoherent modulation technique and decoding the demodulation reference signal. The data sequence may be used to reconstruct a version of the demodulation reference signal used to descramble a received version of the demodulation reference signal. The descrambled demodulation reference signal may be used to estimate a data channel between a transmitting device and a receiving device.

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 for estimating one or more environmental factors at a first user equipment (UE). The one or more environmental factors may be based on estimates of a Doppler spread and a power delay profile (PDP) taken over a set of subsets of a time period, based on multiple signals received from a second UE or a base station over the time period. The first UE may estimate the Doppler spread and PDP for a channel over each of the set of subsets of the time period, and may combine the Doppler spread over the set of subsets and combine the PDP over the set of subsets. The first UE may use the combined Doppler spread and the combined PDP to determine one or more communication parameters for the channel.

Abstract: Methods, systems, and devices for wireless communication are described. A communication device, such as a user equipment (UE) may receive control signaling (e.g., a downlink control information (DCI), a radio resource control (RRC) message, a medium access control-control element (MAC-CE)) including an indication of a set of constellation points for a set of constellation distortion points. The set of constellation distortion points may be of a constellation distribution associated with a modulation scheme (e.g., a quadrature amplitude modulation (QAM), an amplitude and phase-shift keying (APSK)). The UE may perform a digital post distortion operation based on the set of constellation points for the set of constellation distortion points of the constellation distribution, and decode the wireless communication based on performing of the digital post distortion operation.