Abstract: Certain aspects of the present disclosure provide techniques for unlicensed channel occupancy time sharing based on received signal strength. A method that may be performed by a first user equipment (UE) includes receiving a first transmission from a second UE, the first transmission indicating the second UE has acquired a frequency band for a channel occupancy time (COT). The method may also include transmitting a signal within the frequency band during the COT in response to a signal strength of the first transmission as received by the first UE being greater than at least one threshold.

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) includes measuring, starting at least at a start time of a time interval, a frequency band to determine whether the frequency band is idle, the time interval including a plurality of time periods. While measuring the frequency band, decoding, by the UE, any signals received on the frequency band to determine if a clear-to-send (CTS) signal is received over the frequency band.

Abstract: Certain aspects of the present disclosure provide a method for wireless communications by a transmitter UE. The method generally includes transmitting data to at least one receiver UE in an unlicensed spectrum used for sidelink communication, determining if a resource in a slot is available for the at least one receiver UE to provide acknowledgment feedback for the data transmission, and transmitting a reservation signal in the slot if the resource is determined to be available.

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 refraining from transmitting during a gap portion of a first symbol in time of a sidelink transmission, wherein the first symbol comprises the gap portion and a signal portion; transmitting a signal during the signal portion of the first symbol; and transmitting a data signal of the sidelink transmission in at least one second symbol subsequent in time to the first symbol in the sidelink transmission.

Abstract: Certain aspects of the present disclosure provide techniques for carrier selection for sidelink communications in an unlicensed spectrum. A method that may be performed by a first sidelink user equipment (UE) includes determining one or more carriers, from a set of configured carriers, in an unlicensed spectrum to use for communicating with a second sidelink UE and communicating with the second sidelink UE using the determined one or more carriers.

Abstract: Certain aspects of the present disclosure provide techniques for subchannel-based listen before talk (LBT). An example method that may be performed by a user equipment (UE) includes receiving one or more transmissions indicating one or more allocated subchannels of a frequency band that are allocated during a first time period, the frequency band comprising the one or more allocated subchannels and one or more unallocated subchannels during the first time period; sensing the one or more unallocated subchannels for at least a portion of the first time period prior to a second time period; and transmitting a signal within the frequency band during the second time period based on energy sensed for the one or more unallocated subchannels being less than a threshold.

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 device includes sensing that an unlicensed frequency band is idle, the unlicensed frequency band consisting of a plurality of subchannels. The method also includes, in response to sensing that the unlicensed frequency band is idle, transmitting, by the first device, at least one of a data signal or a reservation signal during an entire duration of a time period over one or more subchannels of the plurality of subchannels, the at least one of the data signal or the reservation signal reserving the unlicensed frequency band during the time period.

Abstract: Methods, systems, and devices for wireless communications are described to reduce interference caused by power leakage. A first user equipment (UE) or a base station may select communication resources for a sidelink communication based on a distance between UEs reserving frequency resources in a same time window. The first UE or the base station may determine a distance parameter between the first UE and one or more other UEs (e.g., including a second UE) reserving frequency resources within the time window. The distance parameter may represent a physical distance between the first and second UEs or a reference signal received power of the second UE as received by the first UE. The first UE or the base station may select communication resources based on whether the distance parameter is below a threshold, and the first UE may communicate the sidelink communication using the selected resources.

Abstract: Methods, systems, and devices for wireless communications are described. A user equipment may determine parameters for congestion metrics based on a type for a channel access procedure associated with a sidelink transmission. The user equipment may determine a channel access procedure type for a sidelink channel transmission, and determine a limit for a channel occupancy (e.g., a channel occupancy ratio) based on the type. The user equipment may compare the channel occupancy with the limit to determine whether to transmit the sidelink channel transmission, based on whether the channel is available. In some aspects, the user equipment may additionally perform the channel access procedure (e.g., a listen before talk procedure) to determine whether to transmit the sidelink channel transmission. The user equipment may also perform channel measurements to obtain a congestion metric (e.g., a channel busy ratio) based on a threshold before transmitting the sidelink channel transmission.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment may transmit, in a first slot within a channel occupancy time (COT), a first communication; determine whether one or more transmission criteria are satisfied for transmission of a second communication in a second slot within the COT; and selectively transmit the second communication in the second slot within the COT based at least in part on a result of determining whether the one or more transmission criteria are satisfied. Numerous other aspects are provided.

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; determine a range metric for die shared channel occupancy based at least in part on location information; determine whether to share the shared channel occupancy for packet transmission using the packet transmission resource based at least in part on the range metric; and selectively transmit one or more packets in the shared channel occupancy based at least in part on a result of determining whether to share the shared channel occupancy. Numerous other aspects are provided.

Abstract: Methods, systems, and devices for wireless communications are described. A first user equipment (UE) may transmit the sidelink message to a second UE via a sidelink communications channel of an unlicensed radio frequency spectrum band. The first UE or the second UE may transmit a reservation signal to retain the sidelink communication channel for corresponding feedback for the sidelink message (e.g., while the second UE generates a feedback transmission). The second UE may transmit the feedback transmission over the sidelink communication channel.

Abstract: Certain aspects of the present disclosure provide methods and apparatus for determining a Zone identifier (ID), Zone Center, and negative acknowledgement (NACK) ranges. Included are operations and means at a receiving user equipment (UE) to determine a current geographic location (GLL) of the receiving UE, and select a Zone ID based on a two-dimensional (2-D) lookup into an indexed array with the current GLL, the indexed array storing Zone data for one or more geographic Zones. The Zone data for each geographic Zone may be indexed according to geographic position, and include a Zone ID, Zone center, and one or more NACK ranges, each NACK range corresponding with a geographic Zone disposed about the geographic Zone corresponding to the Zone ID. Operations further include performing a NACK operation based on the selected Zone ID and a NACK range.

Abstract: Certain aspects of the present disclosure provide techniques for sidelink communications in an unlicensed spectrum. A method that may be performed by a device includes sensing a channel for interference in each of a plurality of time intervals in order of time until interference below a threshold is sensed for one of the plurality of time intervals or interference above the threshold is sensed for all of the plurality of time intervals, the plurality of time intervals being of a time window. The method may also include sensing interference to be above a threshold in a first portion of the one of the plurality of time intervals. The method may also include sensing interference to be below the threshold in a second portion of the one of the plurality of time intervals that occurs later in time than the first portion.

Abstract: Disclosed are techniques for wireless communication. In an aspect, a first UE determines a set of resources for transmission of one or more sidelink PRSs. The first UE transmits a sidelink control message to reserve the set of resources for the transmission of the one or more sidelink PRSs. In another aspect, the second UE may receive the sidelink control message, and may (e.g., transmit and/or receive/measure) the one or more PRSs in accordance with the sidelink control message. In another aspect, a third UE may receive the sidelink control message, and may determine whether a transmission by the third UE on some or all of the set of resources is permitted based on the sidelink control message.

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: 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: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a sidelink transmitting (Tx) mobile station may perform a sub-band channel access in candidate frequency resources of an unlicensed band for a sidelink positioning reference signal (PRS) transmission to occur in time resources. The Tx may transmit, from the sidelink Tx mobile station to a sidelink receiving (Rx) mobile station, the sidelink PRS transmission in one or more sub-bands of the unlicensed band that have passed the sub-band channel access. Numerous other aspects are described.

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: Methods, systems, and devices for wireless communications are described. The methods include determining a sidelink message to transmit to a second user equipment (UE) over a time resource of a sidelink connection between a first UE and the second UE, encoding at least a subset of time periods of the time resource according to a configuration that is based on a switching time for the second UE for switching from a receiving mode to a transmitting mode during reception of the sidelink message during at least the subset of time periods of the time resource, and transmitting the sidelink message to the second UE using a set of time periods of the time resource that includes the subset of time periods.