Abstract: A user equipment (UE) may communicate with one or more other UEs using multiple transmissions in a device-to-device (D2D) communications deployment. A number of UEs may be configured with D2D resources, and a transmitting UE may identify available D2D resources from the configured resources. The transmitting UE may identify a resource for a first transmission of a D2D transmission from the available D2D resources, and may identify a second resource for a second transmission of the D2D transmission. The second transmission may be a blind HARQ transmission that may be transmitted to enhance the likelihood that one or more receiving UEs successfully receive the transmission. In some examples, the second resource may be identified based on other available resources within an predetermined time window around the first transmission.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may transmit a first message identifying a set of UEs comprising one or more other UEs with which the UE is engaging in sidelink communication. The UE may transmit a second message, based at least in part on a determination of a loss of a sidelink connection to a previously-connected UE of the set of UEs, identifying a subset of the set of UEs and indicating the loss of the sidelink connection. Numerous other aspects are provided.

Abstract: Various aspects of the disclosure relate to the selection and use of modulation and coding scheme (MCS) values. For example, a first MCS table may be used for a first condition and a second MCS table used for a second condition. The disclosure relates in some aspects to inter-device signaling that indicates which MCS table is to be used for communication between the devices.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive, from a base station, a discontinuous reception (DRX) configuration to be used by the UE for cellular communication with the base station, wherein the DRX configuration indicates a DRX cycle that includes an active time during which the UE is to monitor a physical downlink control channel (PDCCH) and an inactive time during which the UE is to refrain from monitoring the PDCCH; identify a time window for sidelink communication with another UE based at least in part on the DRX configuration; and communicate using one or more sidelink resources in the identified time window. Numerous other aspects are provided.

Abstract: Aspects of the present disclosure provide synchronization techniques for user equipment (UEs) that may be otherwise unable to support sidelink communication a synchronized UE and may have also lost global navigation satellite system (GNSS) and/or Evolved Node Base Stations (eNBs) as a synchronization source. In such instance, the unsynchronized UE may utilize reference signals (RS) from the data packets received from other UEs to track the timing and perform autonomous timing adjustments based thereon for synchronized packet transmission or reception.

Abstract: Methods, systems, and devices for wireless communications are described in which two or more UEs of a wireless communications system may establish a sidelink connection. A first UE that is initiating sidelink communications may evaluate whether the sidelink connection can support a quality of service (QoS) for a data flow prior to admitting the data flow. The first UE may evaluate a link quality with one or more other UEs that are to use the data flow on the sidelink connection, evaluate system congestion of time/frequency resources that are available for the sidelink connection, or any combinations thereof, and admit the data flow based on the evaluation. A link quality of the sidelink connection may be determined based on a type of communication associated with the data flow, such as unicast communications with one other UE, multicast communications with multiple other UEs, or broadcast transmissions to multiple UEs.

Abstract: Aspects described herein relate to receiving, over a sub-channel of multiple sub-channels, ultra-reliable quality-of-service (QoS) traffic from one or more UEs over a time duration wherein other sub-channels of the multiple sub-channels are used for initial ultra-reliable QoS transmissions from one or more other transmitting UEs over the time duration, and relaying, along with one or more other relaying UEs, the ultra-reliable QoS traffic over a subsequent time duration.

Abstract: Methods, systems, and devices for wireless communications are described. A first wireless device may receive an indication of one or more parameters for communications over a sidelink channel during a first time period, where the one or more parameters may include a time threshold for a second resource pool. The wireless device may transmit data over a first resource pool of the sidelink channel during a first portion of the first time period based on the one or more parameters, the first resource pool including resources for communications between the first wireless device and a second wireless device. The wireless device may monitor the second resource pool during a second portion of the first time period for the time threshold, the second resource pool including resources for communications between the first wireless device and a third wireless device.

Abstract: Methods, systems, and devices for wireless communications are described. A device may determine a packet for transmission and determine whether to transmit a reservation signal prior to the transmission of the packet based in part on a condition. The condition may include, but is not limited to, a packet size, or a packet priority, or a combination thereof. According to the determination, the device may refrain from transmitting the reservation signal or allocate resources for the reservation signal from a same resource pool associated with the transmission of the packet or a dedicated resource pool according to a pre-reservation resource pattern.

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: Methods, systems, and devices for wireless communications are described. A user equipment (UE) may transmit concurrent messages over a sidelink channel to another UE and over an uplink channel to a base station. The UE may transmit, to a base station, a report indicating a capability of the UE to concurrently transmit over a sidelink channel and an uplink channel. The UE may receive, from the base station and based on the report, a transmission configuration scheduling a concurrent sidelink and uplink transmission within a resource shared by the sidelink channel and the uplink channel. The UE may then transmit the concurrent sidelink and uplink transmission within the resource shared by the sidelink channel and the uplink channel based on the transmission configuration. The other UE and the base station may receive the concurrent sidelink and uplink transmission and may decode different layers of the transmission.

Abstract: In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a UE. The apparatus may receive from a second device a first data packet in one or more receiving slots of a time division duplex frame that includes a plurality of slots. The apparatus may determine whether the first data packet is received incorrectly. The apparatus may wait until the end of the one or more receiving slots and may transmit to the second device a first NACK in a NACK feedback symbol in a configured slot after the end of the one or more receiving slots in response to determining that the first data packet was not received correctly.

Abstract: Methods, systems, and devices for wireless communications are described. A first user equipment (UE) may establish a sidelink connection with a second UE, where the sidelink connection is associated with a plurality of flows. The first UE may determine, based on monitoring each flow of the plurality of flows, a radio link status of the sidelink connection. The first UE may transmit, based on the determining, a non-access stratum layer message to the second UE based at least on the radio link status of the sidelink connection.

Abstract: Methods, systems, and devices for wireless communications are described. A communication device, which may be otherwise known as user equipment (UE), may identify a default modulation and coding scheme table and a preconfigured modulation and coding scheme table associated with a resource pool. The UE may receive, from a transmitting communication device, an indication of the preconfigured modulation and coding scheme table to use for upcoming sidelink communications. The UE may then communicate based on the preconfigured modulation and coding scheme table.

Abstract: In a particular implementation, a method of wireless communication includes transmitting, from a first user equipment (UE) to a second UE, a radio resource control (RRC) request that includes a first discontinuous reception (DRX) preference at the first UE. The method also includes receiving, at the first UE from the second UE, a RRC setup message that includes a second DRX preference at the second UE. The method further includes transmitting, from the first UE to the second UE, a RRC setup complete message that includes an indication of a confirmed DRX cycle.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment may generate a pseudorandom noise (PN) sequence, modulate the PN sequence based at least in part on a modulation order parameter, and transmit the PN sequence in one or more symbols prior to transmitting sidelink data. The one or more symbols used to transmit the PN sequence may be used for automatic gain control (AGC) training at a receiving device. The user equipment may then transmit the sidelink data in a plurality of symbols that are subsequent in time relative to the one or more symbols used to transmit the PN sequence, and the receiving device may process the sidelink data based on the AGC training. Numerous other aspects are provided.

Abstract: The disclosure relates in some aspects to sharing wireless communication resources. For example, a first type of device allocated to use a first resource pool may dynamically use a second resource pool allocated for a second type of device. The first type of device may use an entry criteria to determine whether to use the second resource pool. In some aspects, the entry criteria may specify that resource sharing is permitted if a ratio of resources used by devices of the second type (relative to the total resources in the second resource pool) is less than a threshold. In addition, the first type of device may use an exit criteria to determine whether to stop using the second resource pool. In some aspects, the exit criteria may specify that resource sharing should stop if a ratio of resources used by devices of the second type is greater than a threshold.

Abstract: Methods, systems, and devices for wireless communication are described. One method for wireless communication at a first device includes receiving a multicast packet from a second device, decoding control header information in the received multicast packet, determining that a decoding procedure associated with a payload of the received multicast packet is unsuccessful and transmitting a negative acknowledgement (NACK) based at least in part on the determining. The method also includes retrieving a list of transmitter identifiers. In some cases, transmitting the NACK is based at least in part on the list of transmitter identifiers. The method further includes determining a transmitter identifier associated with the multicast packet and determining that the transmitter identifier is present in the list of transmitter identifiers.

Abstract: Certain aspects of the present disclosure provide a method for wireless communications between a first UE and a second UE. The method includes, at the first UE, receiving, from the second UE, a paging indication message on a sidelink channel, the paging indication message associating the first UE with one or more resources of a common resource pool that includes a plurality of resources for communication on the sidelink channel. The method further includes, based on the received paging indication message, monitoring the one or more resources for a message from the second UE.

Abstract: Certain aspects of the present disclosure provide a method for wireless communications by a first UE. The method includes receiving a data transmission from a second UE. The data transmission is associated with a feedback procedure for data transmissions that is based on a distance between the first UE and a transmitting UE. When the first UE (i) cannot successfully decode the data transmission and (ii) cannot determine the distance between the first UE and the second UE, the method includes determining whether one or more criteria are satisfied for sending, to the second UE, a negative acknowledgement (NACK) for the data transmission as part of the feedback procedure, where the NACK indicates the first UE could not successfully decode the data transmission. The method including transmitting the NACK to the second UE when the one or more criteria are satisfied.