Abstract: Methods, systems, and devices for wireless communications are described to support relayed sidelink communications. A first device and a base station may communicate via a communication link including a sidelink link between the first device and a second device and a relay link between the second device and the base station. The base station may determine restrictions for the communication link and transmit an indication of the restrictions over the relay link. The restrictions may differentiate data originating from the first device and the second device, restrict the first device to one or more resources, or associate logical channels at the first device with one or more transport block sizes and communication links. The second device may relay the indication of the restrictions to the first device. The first device, the second device, and the base station may communicate over the communication link according to the restrictions.

Abstract: Wireless communication devices are adapted to facilitate power conservation and sidelink communications. According to one example, a wireless communication device can transmit a reservation signal to reserve one or more sidelink resources for use by another device, and receive a sidelink transmission from the other device on at least a portion of the one or more reserved sidelink resources. According to another example, a wireless communication device can detect a reservation signal from another device, where the reservation signal is configured to reserve one or more sidelink resources, and transmit a sidelink transmission on at least a portion of the one or more of the sidelink resources reserved by the other device. Other aspects, embodiments, and features are also included.

Abstract: Aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may determine whether a peer-to-peer (P2P) communication is to be relayed based at least in part on a location of the UE and a range requirement associated with the P2P communication; and transmit the P2P communication, wherein the P2P communication includes an indication of whether the P2P communication is to be relayed. In some aspects, a UE may receive the P2P communication; determine whether to relay the P2P communication based at least in part on the indication and at least one of: a location of the UE, or a UE identifier, included in the P2P communication, that identifies the UE and is associated with a request for the UE to relay the P2P communication; and selectively relay the P2P communication based at least in part on determining whether to relay the P2P communication.

Abstract: Aspects presented herein may enable a transmitting device to encode and transmit coordination information and data in separate transport blocks, such that the transmitting device may update the coordination information without altering the transport block carrying the data. In one aspect, an apparatus encodes coordination information for sidelink resources in a first transport block. The apparatus encodes data in a second transport block. The apparatus transmits a first transmission on a PSSCH, the first transmission including the first transport block comprising coordination information and the second transport block.

Abstract: Aspects described herein relate to generating a configuration indicating whether a minimum communication range parameter in sidelink control information (SCI) corresponds to a location-based value or a signal strength-based value, and transmitting the configuration to one or more UEs.

Abstract: Certain aspects of the present disclosure provide techniques for channel estimation for two-stage sidelink control using sidelink data channel demodulation reference signals (DMRS). A user equipment (UE) can transmit DMRS for the sidelink data channel. The UE may transmit the second stage of the sidelink control using antenna ports or a precoder used for the sidelink data channel. The receiving device may receive the DMRS, estimate the channel, and demodulate the second stage of the sidelink control based on the estimated channel. The receiving device may flexibly determine the DMRS to use for the estimation and demodulation.

Abstract: Aspects relate to wireless communication devices configured to facilitate power conservation and sidelink communications. According to one example, a wireless communication device can transmit a first sidelink transmission, determine one or more sidelink resources for receiving a second sidelink transmission based at least in part on the resources used to transmit the first sidelink transmission, monitor the determined one or more sidelink resources, and receive via the transceiver the second sidelink transmission on the monitored one or more sidelink resources. According to another example, a wireless communication device can receive a first sidelink transmission, determine one or more sidelink resources for transmitting a second sidelink transmission based at least in part on the received first sidelink transmission, and transmit the second sidelink transmission on the one or more of the determined sidelink resources.

Abstract: Certain aspects of the present disclosure provide techniques for wireless in-vehicle networking. A method that may be performed by a device in a vehicle includes wirelessly transmitting a data packet directly via a first device-to-device (D2D) communication link to another device in the vehicle; monitoring for an acknowledgment (ACK) of the data packet; deciding whether to retransmit the data packet to the other device, based on the monitoring; and wirelessly transmitting the data packet to a transmission relay, wherein an intended destination of the data packet is the other device, wherein the monitoring for the ACK comprises monitoring for a first ACK from the other device and a second ACK from the transmission relay.

Abstract: A target user equipment (UE), which may be a vehicle or UE carried by a pedestrian, may receive sequentially broadcast ranging signals from a set of ranging source entities (SEs), which may be road side units or other vehicles. The target UE further receives location information separately broadcast by each SEs. The location information, for example, may include the position for the SE, the time of transmission of the ranging signals transmitted by the SE and/or a sequence identifier for the SE. The target UE may determine ranges to the SEs using time of arrival measurements for the ranging signals and the time of transmissions of the ranging signals or the sequence identifier received in the location information. The position of the target UE may be determined using the determined ranges to the SEs and the positions of the SEs received in the location information.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may determine whether sufficient resources are available to perform a transmission in a current slot. The UE may transmit the transmission in the current slot, transmit an early reservation signal for a future resource, or determine whether sufficient resources are available to perform the transmission in a subsequent slot based at least in part on a probability-based determination and based at least in part on whether sufficient resources are available to perform the transmission in the current slot. Numerous other aspects are provided.

Abstract: Certain aspects of the present disclosure provide techniques for improving sidelink positioning via messaging between wireless nodes, e.g., roadside service units (RSUs). A method that may be performed by a user equipment (UE) includes receiving a first positioning reference signal (PRS) from a first wireless node, receiving a second PRS from a second wireless node, receiving, from the first wireless node, an estimate of a first clock error component between the first wireless node and the second wireless node, and estimating a position of the UE, based on the first PRS, the second PRS, and the estimate of the first clock error component.

Abstract: Methods, systems, and devices for wireless communications are described. A user equipment (UE) may communicate with one or more other UEs over a sidelink communications link, and may perform radio link monitoring (RLM) of the sidelink. A first UE may transmit, to a second UE, a first message in a first transmission time interval (TTI) via a sidelink communication link. The first UE may monitor the sidelink communications link during a second TTI subsequent to the first TTI for a feedback message from the second UE in response to the first message transmitted by the first UE. The monitoring may be a part of a RLM procedure for the sidelink communications link. The first UE may increment a counter based on or an unsuccessful receipt of the feedback message in the second TTI.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may transmit an indication that the UE is to transition to a sidelink discontinuous reception (DRX) sleep mode. The UE may transition to the sidelink DRX sleep mode based at least in part on transmitting the indication. 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 receive one or more sidelink communications on a sidelink between the UE and another UE. The UE may transmit one or more hybrid automatic repeat request (HARQ) feedback communications, associated with the one or more sidelink communications, on the sidelink and in a HARQ feedback resource included in a multi-slot feedback reporting period. The HARQ feedback resource may include a set of negative acknowledgement (NACK) resources or the set of NACK resources and a set of acknowledgement (ACK) resources. Numerous other aspects are provided.

Abstract: Certain aspects of the present disclosure provide techniques for configuring sidelink communications between user equipment's (UEs). Per one technique, during a discovery opportunity, a first UE and a second UE may identify a subset of beam pairs suitable for communication, and schedule a discontinuous transmission (DTX) occasion during the discovery opportunity. During the DTX occasion, the first UE and second UE may perform a beam refinement procedure to determine a beam pair (BP) over which to communicate, from the identified subset of beam pairs. The beam refinement procedure may include beam narrowing of at least one of the identified subset of beam pairs.

Abstract: A method of wireless communication wireless communication by an identifier-receiving user equipment (UE) includes measuring a received signal power of multiple resource UEs. The method also includes receiving a set of identifiers from an identifier-transmitting UE. The method further includes identifying a resource used by at least one of the multiple resource UEs for a future transmission from the identifier-receiving UE based on the measured received signal power and the received set of identifiers. The method still further includes scheduling the future transmission on the at least one identified resource.

Abstract: Techniques for wireless communications are described. A user equipment (UE) may be configured with one or multiple transmission and reception points (TRPs). The UE may support sidelink communications, which may be referred to as vehicle-to-everything (V2X) communications systems, vehicle-to-vehicle (V2V) communications systems, and the like. The UE may provide improvements to resource determination for the sidelink communications by determining whether multiple peer UEs can be space-division multiplexed over time and frequency resources. To mitigate interference between the multiple peer UEs, the UE may transmit a power control request message to one or multiple peer UEs to adjust a transmit power level, and a receive a power control response message from the one or multiple peer UEs accepting or rejecting the transmit power level adjustment. As a result, the UE may experience efficient sidelink operations.

Abstract: Wireless communication systems and methods related to sidelink communications are provided. A first user equipment (UE) determines a discontinuous operation configuration that indicates an on-duration period for a sidelink communication and a cycle of discontinuous operation. The first UE communicates with at least one other UE during the on-duration period indicated by the discontinuous operation configuration. The first UE uses a base configuration and an on-duration parameter, an offset parameter, and a cycle parameter to determine a discontinuous operation configuration for the first UE.

Abstract: In one aspect, a method includes determining, by a user equipment (UE), a channel busy ratio (CBR) window for a CBR measurement for one or more resources; determining, by the UE, a CBR measurement value for the CBR window and for the one or more resources; determining, by the UE, a channel occupancy ratio (CR) window based on a first number of subframes used for a history of past transmissions and based on a second number of subframes used for future planned transmissions and corresponding retransmissions; and determining, by the UE, a CR value for the CR window based on subchannels used for the one or more resources for the first number of subframes and based on subchannels estimated for the one or more resources for the second number of subframes. In another aspect, a method includes determining a CR window based on a CBR measurement value.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may identify one or more spectral efficiency ranges that are to be used to select a modulation and coding scheme (MCS) for a sidelink communication. The UE may transmit the sidelink communication using the MCS selected based at least in part on the one or more spectral efficiency ranges. Numerous other aspects are provided.