Abstract: Apparatus, methods, and computer-readable media for facilitating autonomous synchronization are disclosed herein. For example, a UE may be configured to perform an initial synchronization directly to PSCCH and PSSCH when other synchronization sources, such as GNSS, a base station, and/or SLSS, are unavailable. An example method for wireless communication at a user equipment includes receiving a PSCCH. The example method also includes performing an initial synchronization based on the PSCCH. In some examples, the method may also include receiving a PSSCH, and determining a logical subframe number modulo 10 based on the PSSCH. The logical subframe number modulo 10 may correspond to a sequence seed.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a first user equipment (UE) may receive, from a second UE, a second synchronization signal at a reception time. The first UE may adjust a transmission time of a first synchronization signal, resulting in an adjusted transmission time, wherein the adjusted transmission time is based at least in part on the reception time of the second synchronization signal. The first UE may transmit the first synchronization signal at the adjusted transmission time. Numerous other aspects are described.

Abstract: A transmitting device maps complex valued symbols in sequence to physical resource blocks for a sidelink transmission. The transmitting device reserves a first symbol of a subframe, where resource elements in the first symbol of the subframe are not considered in mapping the complex valued symbols to the physical resource blocks for the sidelink transmission. The transmitting device transmits the sidelink transmission after mapping the complex valued symbols to the physical resource blocks. A receiving device receives the sidelink transmission and decodes the sidelink transmission to determine complex valued symbols that are mapped in sequence to physical resource blocks of the sidelink transmission, where the complex valued symbols are not mapped to resource elements in a first symbol of a subframe.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a network node may obtain a demodulation reference signal (DMRS) having a constant envelope in a time domain. The network node may generate a communication signal based at least in part on multiplexing the DMRS with a plurality of data resource elements. Numerous other aspects are described.

Abstract: An apparatus for wireless communication includes a receiver and a transmitter that is configured to transmit a signal during a first slot. The signal has a power level that is associated with a transmission that is to occur during the first slot or during a second slot after the first slot. The signal is distinct from the transmission. The first slot and the second slot occur during a sub-frame time interval associated with a first cellular vehicle-to-everything (CV2X) wireless communication protocol, and the first slot and the second slot are associated with a second CV2X wireless communication protocol different than the first CV2X wireless communication protocol. The transmitter is further configured to perform the transmission during the second slot based on the power level.

Abstract: Methods, systems, and devices for wireless communications are described. In some examples, when a high subcarrier spacing (SCS) is used for sidelink communications, the user equipments (UEs) may use a modified sidelink slot structure for the sidelink communications. In one example, the slot structure may include at least two automatic gain control (AGC) symbols with at least one sidelink control channel symbol between the two AGC symbols. The UE may perform an AGC procedure during the two AGC symbols and the sidelink control channel symbol. In some examples, the slot structure may include bundled slots to minimize per slot overhead associated with AGC symbols and sidelink control channel symbols. For example, at a high SCS, the slot structure may include a first slot including multiple AGC symbols, Subsequent bundled slots may not include AGC symbols and/or sidelink control channel symbols.

Abstract: Methods, systems, and devices for wireless communications are described. The method includes communicating control signaling scheduling a sidelink transmission via a physical sidelink channel, receiving, by a first user equipment (UE), the sidelink transmission including one or more reference signals from a second UE via the physical sidelink channel based on the control signaling, and monitoring the physical sidelink channel based on time synchronization, frequency synchronization, or both, determined using the one or more reference signals.

Abstract: Apparatus, methods, and computer-readable media for facilitating autonomous synchronization are disclosed herein. For example, a UE may be configured to perform an initial synchronization directly to PSCCH and PSSCH when other synchronization sources, such as GNSS, a base station, and/or SLSS, are unavailable. An example method for wireless communication at a user equipment includes receiving a PSCCH. The example method also includes performing an initial synchronization based on the PSCCH. In some examples, the method may also include receiving a PSSCH, and determining a logical subframe number modulo 10 based on the PSSCH. The logical subframe number modulo 10 may correspond to a sequence seed.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a receiver mobile station may receive at least one sidelink signal. The receiver mobile station may transmit an indication of a requested transmission diversity scheme, of a plurality of transmission diversity schemes, based at least in part on the at least one sidelink signal. Numerous other aspects are described.

Abstract: A transmitting device maps complex valued symbols in sequence to physical resource blocks for a sidelink transmission. The transmitting device reserves a first symbol of a subframe, where resource elements in the first symbol of the subframe are not considered in mapping the complex valued symbols to the physical resource blocks for the sidelink transmission. The transmitting device transmits the sidelink transmission after mapping the complex valued symbols to the physical resource blocks. A receiving device receives the sidelink transmission and decodes the sidelink transmission to determine complex valued symbols that are mapped in sequence to physical resource blocks of the sidelink transmission, where the complex valued symbols are not mapped to resource elements in a first symbol of a subframe.

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 communications are described to support estimation of a transmission quality imbalance between a set of antennas of a first user equipment (UE). The first UE may use the estimated transmission quality imbalance to determine a transmission diversity scheme that may decrease the transmission quality imbalance. The first UE may determine the transmission quality imbalance between the set of antennas by estimating a reception quality imbalance between the set of antennas. The first UE may estimate the reception quality imbalance for multiple subsets of a time period and may combine the reception quality imbalance estimations for the multiple subsets. The combined reception quality imbalance estimations may represent the transmission quality imbalance between the set of antennas, which may be used to determine a transmission diversity scheme for communicating a transmission to a second UE or a base station.

Abstract: A transmitting device maps complex valued symbols in sequence to physical resource blocks for a sidelink transmission. The transmitting device reserves a first symbol of a subframe, where resource elements in the first symbol of the subframe are not considered in mapping the complex valued symbols to the physical resource blocks for the sidelink transmission. The transmitting device transmits the sidelink transmission after mapping the complex valued symbols to the physical resource blocks. A receiving device receives the sidelink transmission and decodes the sidelink transmission to determine complex valued symbols that are mapped in sequence to physical resource blocks of the sidelink transmission, where the complex valued symbols are not mapped to resource elements in a first symbol of a subframe.

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: Aspects relate to mechanisms for a wireless communication device to select between a cyclic delay diversity mode and an antenna switch diversity mode for transmission of a signal based on at least one parameter associated with communication over a wireless channel. The parameter(s) may include a channel estimation parameter associated with the wireless channel, a communication parameter associated with at least one communication on the wireless channel, or a combination thereof.

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 communications are described. Some wireless communications systems may support communications. For example, a wireless communications system may support New Radio (NR) cellular-vehicle to everything (C-V2X) communication. In some examples, a user equipment (UE) may receive a sidelink control channel for a sidelink transmission on a first set of symbols of a time slot (e.g., the first two or three symbols of a time slot). The UE may decode the sidelink control channel and disable one or more radio frequency (RF) components associated with processing the sidelink transmission on a second set of symbols of the time slot based on decoding the sidelink control channel. For example, the UE may disable one or more RF components if the UE determines the sidelink control channel is decoded unsuccessfully.

Abstract: Methods, systems, and devices for wireless communications are described to support estimation of a transmission quality imbalance between a set of antennas of a first user equipment (UE). The first UE may use the estimated transmission quality imbalance to determine a transmission diversity scheme that may decrease the transmission quality imbalance. The first UE may determine the transmission quality imbalance between the set of antennas by estimating a reception quality imbalance between the set of antennas. The first UE may estimate the reception quality imbalance for multiple subsets of a time period and may combine the reception quality imbalance estimations for the multiple subsets. The combined reception quality imbalance estimations may represent the transmission quality imbalance between the set of antennas, which may be used to determine a transmission diversity scheme for communicating a transmission to a second UE or a base station.

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: User equipment (UE) may benefit from power management techniques, for example, in the context of cellular vehicle-to-everything (CV2X) communication. In various aspects of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a UE configured to determine whether a first subframe includes at least one sub-channel carrying information intended for the UE, receive the information via at least one receive (Rx) chain associated with the at least one sub-channel when the information intended for the UE is carried on the at least one sub-channel included in the first subframe, and deactivate the at least one Rx chain associated with the at least one sub-channel based on whether the information intended for the UE is absent from the at least one sub-channel included in the first subframe.