Abstract: Method and apparatus for downlink control channel for transmit equalization waveforms for XR devices. The apparatus configures a payload comprising at least sidelink control data and a transmit equalization matrix for transmission within a transmit pre-equalization refresh period. The sidelink control data comprising at least one of a first part or a second part. The apparatus applies an equalization procedure to the payload based at least on the transmit equalization matrix. The apparatus transmits, to a second wireless device, the payload comprising at least the sidelink control data and the transmit equalization matrix.

Abstract: Methods, systems, and devices for wireless communications are described. A user equipment (UE) may perform an initialization procedure with an extended reality (XR) device including a time synchronization and a frequency synchronization. The UE may receive, from the XR device and at a first periodicity, first pilot signals, and may transmit, based on receiving the first pilot signals, a first control message indicating a first set of correction factors to apply to at least one of the time synchronization or the frequency synchronization. The UE may transmit, to the XR device and at a second periodicity, a second pilot signal, and may receive, from the XR device, a second control message including samples of the second pilot signal. The UE may transmit, based on the samples, a third control message indicating a second set of correction factors to apply to the time synchronization between the UE and the XR device.

Abstract: Methods, systems, and devices that support channel estimation reference signals for pre-equalization are described. In some examples, channel state information (CSI) for a link between a user equipment (UE) and another wireless device may be acquired by the UE based on samples of a downlink reference signal transmitted from the UE to the wireless device. Specifically, the wireless device (e.g., an extended reality (XR) device) may obtain samples of the downlink reference signal (e.g., a channel estimation reference signal) and report or indicate (e.g., transmit) the samples to the UE via an uplink transmission. For example, the reference signals may be sampled at the wireless device side, and CSI may be obtained using the samples signaled back to the UE by the wireless device. The UE may perform channel estimation based on the received samples, which may enable transmit pre-equalization of signals sent to the wireless device.

Abstract: Methods, systems, and devices for wireless communications are described. A user equipment (UE) may perform an initial pairing procedure with an extended reality (XR) device via a narrow band (NB) sidelink connection. The initial pairing procedure may establish an ultra wideband (UWB) sidelink connection between the UE and the XR device. The UE may transmit control signaling indicating a set of resources for the UWB sidelink connection. The set of resources may correspond to a local timeline for sidelink communications between the UE and the XR device. The UE may translate a cellular timeline for communications to generate the local timeline. The UE may transmit a triggering signal via the NB sidelink connection initiating sidelink communications between the UE and the XR device according to the local timeline for sidelink communications.

Abstract: Methods, systems, and devices for wireless communications are described. In some cases, a network entity may estimate an uplink sampling time offset (STO) associated with a user equipment (UE) based on an uplink signal from the UE and may remove the uplink STO from a first estimated channel to generate a second estimated channel. Thus, the network entity may equalize a first downlink signal in accordance with the second estimated channel and may transmit the first downlink signal to the UE. The network entity may additionally receive an indication of a downlink STO associated with the UE based on transmission of the first downlink signal and may equalize a second downlink signal in accordance with a third estimated channel, where the third estimated channel is based on (e.g., free of) the uplink STO and the downlink STO.

Abstract: Certain aspects of the present disclosure provide techniques for using phase tracking reference signals (PTRSs) for transmission pre-equalization modes. A method generally includes sending, to a device, one or more capability indications, the one or more capability indications indicating a support for a transmission pre-equalization mode; receiving, from the device, a message comprising one or more PTRS pilot signals, the message comprising the one or more PTRS pilot signals based on the one or more capability indications; and obtaining, from the message, one or more receiver side measurements, the one or more receiver side measurements obtained based on the one or more PTRS pilot signals. In some aspects, the device may perform a transmission pre-equalization of the message, the transmission pre-equalization performed based on the support for the transmission pre-equalization mode.

Abstract: A device may one or more memories, individually or in combination, having instructions. A device may one or more processors, individually or in combination, configured to execute the instructions and cause the apparatus to: receive a sampled reference signal; and transmit an indication of a communication scheme selected from a plurality of communication schemes based at least in part on the sampled reference signal.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may determine a duty cycle for transmitting one or more orthogonal frequency division multiplexing (OFDM) symbols via an ultra-wideband (UWB). The UE may transmit the one or more OFDM symbols via the UWB based at least in part on the duty cycle. Numerous other aspects are described.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a wireless communication device may generate a pre-equalized waveform associated with a multiple-input multiple-output (MIMO) communication system. The wireless communication device may transmit the pre-equalized waveform using a per-MIMO-layer transport block (TB). 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 transmit a first downlink transmission. The UE may receive an uplink transmission that includes channel state information including an indication of one or more samples of the first downlink transmission, wherein the one or more samples, before reception of the uplink transmission, are unprocessed for a channel estimation. The UE may transmit a second downlink transmission in accordance with the channel estimation that is based at least in part on the one or more samples. Numerous other aspects are described.

Abstract: An apparatus may be a wireless device such as a user equipment (UE) configured to receive, from a wireless device associated with the UE, a first indication of a capability to perform an equalization operation and transmit, to the wireless device, a second indication of an allocation of resources associated with a pre-equalized demodulation reference signal (DMRS) for the equalization operation, wherein the allocation of resources is for less than all slots within a set of slots associated with a same pre-equalization.

Abstract: Methods, systems, and devices for wireless communications are described. For example, a transmitting device, such as a user equipment (UE) or network entity, may apply a pre-equalization operation and a normalization operation prior to transmitting a signal with an intra-symbol duty cycle. A receiving device (e.g., a UE or network entity) may receive the pre-equalized signal with a relatively low demodulation complexity based on the transmitting device pre-equalizing the signal. Additionally, or alternatively, the transmitting device may transmit an indication of the duty cycle to the receiving device in addition to the signal. The receiving device may divide the signal into streams and process the streams based on the indication of the duty cycle. Splitting the signal into streams and processing the streams to estimate symbols of the signal may support a relatively low demodulator complexity at the receiving device.

Abstract: Methods, systems, and devices for wireless communications are described. For example, a transmitting device, such as a user equipment (UE) or network entity, may apply a pre-equalization operation and a normalization operation prior to transmitting a signal with an intra-symbol duty cycle. A receiving device (e.g., a UE or network entity) may receive the pre-equalized signal with a relatively low demodulation complexity based on the transmitting device pre-equalizing the signal. Additionally, or alternatively, the transmitting device may transmit an indication of the duty cycle to the receiving device in addition to the signal. The receiving device may divide the signal into streams and process the streams based on the indication of the duty cycle. Splitting the signal into streams and processing the streams to estimate symbols of the signal may support a relatively low demodulator complexity at the receiving device.

Abstract: Methods, systems, and devices for wireless communications are described. In some examples, the first wireless device may transmit, to a second wireless device, a control message indicating a set of pre-equalization transmission schemes supported by the first wireless device for receipt of messaging pre-equalized by the second wireless device. The first wireless device may transmit a measurement report that indicates a measurement of a wireless channel between the first wireless device and the second wireless device, where the measurement may be a signal-to-interference and noise (SINR) measurement. The first wireless device may receive a control signal indicative of a first pre-equalization transmission scheme to be used by the second wireless device for pre-equalization based at least in part on the set of pre-equalization transmission schemes and the measurement.

Abstract: A prediction based frequency domain quantizer for DL reference signal samples indication to support transmit pre-equalization is described. An apparatus is configured to predictively quantize a DL reference signal based on a prior sample of the DL reference signal. The apparatus is configured to provide, for a UE, a quantized representation of the DL reference signal and a set of controlled parameters. The apparatus is configured to receive, from the UE, pre-equalized data in accordance with a channel estimation associated with a reconstructed representation of the DL reference signal after quantization.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may determine a duty cycle for transmitting one or more orthogonal frequency division multiplexing (OFDM) symbols via an ultra-wideband (UWB). The UE may transmit the one or more OFDM symbols via the UWB based at least in part on the duty cycle. Numerous other aspects are described.

Abstract: Method and apparatus for downlink control channel for transmit equalization waveforms for XR devices. The apparatus configures a payload comprising at least sidelink control data and a transmit equalization matrix for transmission within a transmit pre-equalization refresh period. The sidelink control data comprising at least one of a first part or a second part. The apparatus applies an equalization procedure to the payload based at least on the transmit equalization matrix. The apparatus transmits, to a second wireless device, the payload comprising at least the sidelink control data and the transmit equalization matrix.

Abstract: Methods, systems, and devices for wireless communications are described. A user equipment (UE) may establish a wireless connection with a wireless communications device via an unlicensed wireless communications channel. The UE may transmit control signaling to the wireless communications device. The control signaling may include a communications configuration that indicates one or more constraints for communicating within the unlicensed wireless communications channel. In some examples, the constraints may include a minimum bandwidth of the unlicensed wireless communications channel, a Fourier transform constraint, a subcarrier spacing (SCS) constraint, or a combination thereof. The UE may communicate one or more sidelink messages with the wireless communications device via the unlicensed wireless communications channel using a set of communications parameters based on the communications configuration and including a component carrier bandwidth, a fast Fourier transform (FFT) size, and an SCS.

Abstract: Methods, systems, and devices for wireless communication are described. A wireless device may receive, from another device (e.g., a user equipment (UE)), a message indicating a configuration of a set of log-likelihood ratio (LLR) scaling reference signals. The configuration may indicate a resource allocation for the set of LLR scaling reference signals, where the resource allocation may be based on a type of waveform used for communications between the wireless device and the UE. The wireless device may receive one or more pre-equalized data transmissions having the waveform type, and the pre-equalized data transmission may include the LLR scaling reference signals in accordance with the resource allocation. The wireless device may perform measurements of the set of LLR scaling reference signals for performing LLR scaling, and the wireless device may decode the one or more pre-equalized transmissions based on the LLR scaling using the set of LLR scaling reference signals.

Abstract: A method for wireless communication at a user equipment (UE) and related apparatus are provided. In the method, the UE obtains channel information for a sidelink channel between the UE and a receiving device and performs a pre-equalization process on a signal to be transmitted to the receiving device based on the channel information to obtain a pre-equalized signal. The UE then transmits the pre-equalized signal to the receiving device through the sidelink channel.