Abstract: Methods, systems, and devices for wireless communications are described. A user equipment (UE) may receive an indication of a time offset for synchronization signal resources for synchronization signals associated with a first radio access technology (RAT). The UE may determine the synchronization signal resources and a synchronization periodicity based on the indication and a penetration ratio of UEs associated with the first RAT. The UE may selectively transmit the synchronization signals on the synchronization signal resources and according to the synchronization periodicity. Additionally, or alternatively, the UE may determine that other synchronization signal resources are allocated for a second RAT and may select resources for communications associated with the first RAT based on determining that the other synchronization signal resources are allocated. The UE may perform communications associated with the first RAT based on selecting the resources.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may configure sidelink control information (SCI) to indicate a plurality of sidelink transmission opportunities that are to be reserved for the UE. The UE may transmit the SCI to one or more other UEs. Numerous other aspects are provided.

Abstract: Methods, systems, and devices for wireless communications are described. A wireless device may receive, from a network entity, a control message for a radar reference signal (RRS) configuration associated with the wireless device. The wireless device may set a timing pattern for the RRS based on the control message and one or more timing parameters for the RRS configuration. The wireless device may transmit the RRS according to the timing pattern. The RRS may include one or more cyclic prefix (CP) sub-symbols and one or more RRS sub-symbols. The wireless device may receive one or more reflections of the RRS and may perform one or more processing operations on the one or more reflections of the RRS using a plurality of sampling windows. A quantity of sampling windows may be equal to a quantity of CP sub-symbols.

Abstract: Methods, systems, and devices for wireless communications are described. A first user equipment (UE) may belong to a group of UEs that includes at least a second UE and a third UE. The first UE may perform a channel access procedure and, when the channel access procedure is successful, may transmit a first positioning reference signal (PRS) over a sidelink communication link to the second and third UEs. The first UE may transmit the first PRS during a first time interval of a transmission window. Based on receiving the first PRS, the second UE may perform a channel access procedure and may transmit a second PRS to the first UE during a second time interval of the transmission window. The second PRS may be multiplexed (e.g., using frequency division multiplexing (FDM) or code division multiplexing (CDM)) with at least a third PRS transmitted by the third UE.

Abstract: To facilitate efficient LBT sidelink sensing procedures, methods, apparatuses, and computer program products are provided. An example method of a sidelink wireless device includes initiating an LBT sidelink sensing procedure including initiating an LBT timer to run for at least a minimum sensing duration in a channel. The example method further includes detecting one or more signals in the channel during the LBT side link sensing procedure. The example method further includes allowing the LBT timer to continue to run.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a transmitter user equipment (UE) may detect an available bandwidth for transmission of a sidelink positioning reference signal. The transmitter UE may transmit the sidelink positioning reference signal in the available bandwidth, wherein a duration of the sidelink positioning reference signal is based at least in part on the available bandwidth. 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 select, from an available resource pool, one or more resources for transmitting a packet on a channel. The UE may determine that a new shared channel occupancy time (COT) has been initiated on the channel. The UE may adapt at least one resource of the one or more resources for transmitting the packet based at least in part on determining that the new shared COT has been initiated. Numerous other aspects are provided.

Abstract: Methods, systems, and devices for wireless communications are described. A first user equipment (UE) may be configured to transmit positioning reference signals (PRSs) to a second UE in an unshared radio frequency spectrum and transmit supplemental PRSs to the second UE in a shared spectrum. The second UE may then use the supplemental PRSs in addition to the PRSs in the unshared spectrum to compute a position of the first UE. In some cases, the first UE may signal a configuration for the supplemental PRSs to the second UE, and, in other cases, a base station may signal the configuration for the supplemental PRSs to the second UE. In any case, because the second UE may use both the PRSs in the unshared spectrum and the supplemental PRSs to compute the position of the first UE, the accuracy of the computed position of the first UE may be improved.

Abstract: Certain aspects of the present disclosure provide techniques for bit interleaving for sidelink communication with interlaced waveform. A method that may be performed by a user equipment (UE) includes mapping first bits and second bits to resource blocks (RBs) such that the first bits are mapped to first subcarriers of the RBs, a first subset of the second bits are mapped to the first subcarriers, and a second subset of the second bits are mapped to second subcarriers of the REs; and transmitting the first bits and the second bits via the RBs according to the mapping.

Abstract: Channel access for sidelink hybrid automatic repeat request (HARQ) feedback transmission in unlicensed spectrum may be performed. A receiving UE may receive a first transmission from a transmitting UE, and, upon reception of a second transmission from the transmitting UE, may transmit a HARQ feedback transmission to the transmitting UE to indicate decoding of the first transmission. Techniques described herein allow coordination between the receiving UE and the transmitting UE for consistent HARQ feedback in the unlicensed spectrum.

Abstract: In one aspect, a method of wireless communication includes receiving, by a user equipment (UE), a sidelink transmission in a first slot of an unlicensed channel The method also includes performing, by the UE, a Channel Access (CA) operation for a hybrid automatic repeat request (HARQ) feedback transmission in a second slot for the sidelink transmission, where the second slot is one of multiple slots configured for HARQ feedback for the sidelink transmission. The method further includes transmitting, by the UE, HARQ feedback transmission in the second slot based on successfully performing the CA operation. Other aspects and features are also claimed and described.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment may receive information identifying a shared channel occupancy for a packet transmission resource and a hop counter value associated with the shared channel occupancy. The user equipment may determine whether to transmit one or more packets in the shared channel occupancy based at least in part on the hop counter value associated with the shared channel occupancy. Numerous other aspects are provided.

Abstract: Certain aspects of the present disclosure provide techniques for resource allocation with collision indication for sidelink communication. A method that may be performed by a first user equipment (UE) includes receiving a first sidelink transmission from a second UE indicating a first resource reservation; receiving a second sidelink transmission from a third UE indicating a second resource reservation; and transmitting, to at least the second UE, feedback comprising: hybrid automatic retransmission request (HARQ) feedback regarding the first sidelink transmission; and an indication of whether a collision is detected by the first UE between the first resource reservation and the second resource reservation.

Abstract: A user equipment (UE) communicates on a shared channel using sidelink transmissions. The UE determines a channel access priority for the sidelink transmission based on a channel access priority for the UE, a channel access priority associated with a packet priority of the sidelink transmission, a congestion level for the channel, or a remaining time in a packet delay budget of the sidelink transmission. The UE performs a channel access procedure based on the channel access priority for the sidelink transmission to assess that the channel is clear prior to transmitting the sidelink transmission, and transmits the sidelink transmission on the channel.

Abstract: Methods, systems, and devices for wireless communications are described. A user equipment (UE) may determine resource selection priority levels associated with available resources for sidelink signaling in an unlicensed radio frequency spectrum band, the resources selection priority levels may be determined based on resource reservation information of the available resources, a time domain location of the available resources, or both. For example, a first resource of the available resources may be associated with a higher priority than a second resource of the available resources in resource selection. The UE may select one or more resources for the sidelink signaling from the available resources based on the resource selection priority levels associated with the available resources. The UE may transmit the sidelink signaling on the unlicensed radio frequency spectrum band using the one or more selected resources.

Abstract: Certain aspects of the present disclosure provide techniques for sidelink communications in an unlicensed spectrum. A method that may be performed by a user equipment (UE) and a base station (BS) includes sensing, prior to a start of a time window, a frequency band to determine whether the frequency band is idle, the time window divided in time into a plurality of time periods, the frequency band divided in time across multiple of the plurality of time periods into a corresponding plurality of resources comprising one or more unassigned resources and one or more assigned resources assigned to one or more other wireless communication devices for wireless communication.

Abstract: Certain aspects of the present disclosure provide techniques for sidelink communications in an unlicensed spectrum. A method that may be performed by a first user equipment (UE) of a plurality of UEs includes sensing a frequency band to determine whether the frequency band is idle, the sensing occurring prior to a first time period. In some examples, the method may include transmitting, by the first UE, one or more signals over the frequency band during the first time period based on determining that the frequency band is idle, the one or more signals indicating that the frequency band is reserved for wireless communication between the plurality of UEs during the first time period.

Abstract: Certain aspects of the present disclosure provide techniques for slot format for sidelink communication. A method that may be performed by a user equipment (UE) includes transmitting a data signal; refraining from transmitting during a gap portion occurring in time after the transmission of the data signal, wherein the gap portion has a duration less than or equal to a threshold; receiving a feedback signal after the gap portion, wherein the feedback signal comprises at least a signal and hybrid automatic retransmission request (HARQ) feedback for the data signal; receiving another signal; and adjusting a gain applied to the other signal based on the signal.

Abstract: Methods, systems, and devices for wireless communications are described in which a user equipment (UE) may reserve one or more time frequency resources in an unlicensed frequency spectrum band for one or more sidelink transmissions. The UE may reserve the time frequency resources through a sidelink message transmitted in a first slot of a shared channel occupancy (CO). The UE may monitor a subset of slots before the reserved time frequency resources for sidelink transmissions from other UEs sharing the CO. The monitoring of the subset of slots may include decoding control messages or control information in each of the subset of slots, a reference signal received power (RSRP) measurement of sidelink transmissions in the subset of slots, channel sensing with energy detection in a sensing window, or a combination thereof. The UE may communicate in the reserved slot based on the monitoring.

Abstract: Certain aspects of the present disclosure provide techniques for enhanced feedback transmission for sidelink communication in unlicensed spectrum.