Abstract: Wireless communications systems and methods are provided. A method of wireless communication may include performing a first listen-before-talk (LBT) procedure associated with a channel, wherein a channel occupancy time (COT) for the channel is acquired based on the first LBT being successful, communicating a first communication signal in a first link direction during the COT, switching from the first link direction to a second link direction different from the first link direction, and communicating after the switching, a second communication signal in the second link direction without performing a second LBT.

Abstract: Hybrid automatic repeat request (HARQ) acknowledgement (ACK) feedback enhancements are disclosed for new radio (NR) unlicensed (NR-U). In the downlink control channel, two sets of identifiers (IDs) may be explicitly or implicitly signaled. The two IDs identify a current set ID and an additional set ID. Where the two IDs match, then the ACK feedback transmitted in the current ACK message will reflect the current transmissions. Otherwise, where the two IDs are different, the additional set ID identifies any previous or different ACK information that should be transmitted for prior transmissions.

Abstract: Wireless communications systems and methods related to constraining no-listen-before-talk (LBT)-based transmissions during link direction switches in a frequency spectrum shared by multiple network operating entities are provided. A first wireless communication device, communicates, with a second wireless communication device, a configuration for determining whether to perform an LBT after a link direction switch. The first wireless communication device communicates, with the second wireless communication device, a first communication signal in a first link direction during a channel occupancy time (COT) period of the first wireless communication device or the second wireless communication device. The first wireless communication device communicates, with the second wireless communication device, a second communication signal in a second link direction different from the first link direction during the COT period based on the configuration.

Abstract: This disclosure provides systems, methods, and apparatuses for wireless communication. In some aspects, a user equipment (UE) may enable adaptive receive diversity (RxD) by receiving an indicator for a channel occupancy time (COT), outside of the COT and in a non-RxD mode, and may transfer to the RxD mode for reception during the COT. After an end to the COT, the UE may return to the non-RxD mode. In this way, the UE enables improved power gain, diversity gain, or spatial nulling gain during a COT, and enables reduced power utilization outside of the COT.

Abstract: The present disclosure relates to wireless communications, and more particularly to enhancements to a random access channel (RACH) procedure for use in New Radio (e.g., 5G) communications in the unlicensed spectrum (also referred to as NR-U). The present disclosure provides a user equipment (UE) or network entity that determines an available RACH occasion (RO) within a slot for a message transmission according to one of a two-step RACH procedure or a four-step RACH procedure, wherein the available RO is adjacent to at least one unavailable RO within the slot. The UE or network entity may further perform, during the RO, the message transmission according to one of the two-step RACH procedure or the four-step RACH procedure.

Abstract: This disclosure provides systems, methods and apparatus, including computer programs encoded on computer storage media, for physical uplink control channel (PUCCH) resource configuration. In one aspect, a base station may schedule a user equipment (UE) for PUCCH transmission based on a time division orthogonal cover code (TD-OCC) or a set of TD-OCCs, a cyclic shift step size or a set of cyclic shift step sizes, a first symbol or a set of first symbols, or a cyclic shift set. The base station may distinguish communications from that UE based on the TD-OCC or set of TD-OCCs, the cyclic shift step size or set of cyclic shift step sizes, the first symbol or set of first symbols, or the cyclic shift set.

Abstract: Wireless communications systems and methods related to communications in a network are provided. A user equipment (UE) may generate during a first time period, an uplink (UL) communication signal based on a scheduled grant or a configured UL grant. The UE may detect a downlink (DL) communication from a base station (BS) during a second time period after the first time period. The DL communication is devoid of the scheduled grant and the configured UL grant. The UE may transmit to the BS, the UL communication signal based on the scheduled grant or the configured UL grant in response to detecting the DL communication.

Abstract: Methods, systems, and devices for wireless communications are described that support listen before talk (LBT) for uplink transmissions using multiple subbands. A base station may support communication with a user equipment (UE) via multiple subbands and may transmit an uplink grant to the UE that allocates resources of the multiple subbands for transmission of a shared data channel by the UE. The base station may include an indication within the uplink grant that indicates to the UE to perform a given type of LBT for each subband. After transmitting the uplink grant, the base station may transmit control information or other signaling (e.g., channel occupancy time system information (COT-SI)) that indicates subbands on which the UE is to perform a given type of LBT or other subbands on which the UE is to perform a different type of LBT.

Abstract: Methods, systems, and devices for wireless communications are described that support listen before talk (LBT) for uplink transmissions using multiple subbands. A base station may support communication with a user equipment (UE) via multiple subbands and may transmit an uplink grant to the UE that allocates resources of the multiple subbands for transmission of a shared data channel by the UE. The base station may include an indication within the uplink grant that indicates to the UE to perform a given type of LBT for each subband. After transmitting the uplink grant, the base station may transmit control information or other signaling (e.g., channel occupancy time system information (COT-SI)) that indicates subbands on which the UE is to perform a given type of LBT or other subbands on which the UE is to perform a different type of LBT.

Abstract: Wireless communications systems and methods related to uplink control channel transmissions with user multiplexing and reference signal transmissions are provided. A first wireless communication device obtains an uplink control channel multiplex configuration. The first wireless communication device communicates, with a second wireless communication device, a grant indicating a plurality of resource blocks spaced apart from each other by at least one other resource block in a shared radio frequency band, the plurality of resource blocks scheduled for multiple wireless communication devices based on the uplink control channel multiplex configuration. The first wireless communication device communicates, with the second wireless communication device, a first uplink control channel signal in one or more of the plurality of resource blocks based on the uplink control channel multiplex configuration.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may identify a control channel resource configuration associated with an unlicensed spectrum, wherein the control channel resource configuration is associated with an indication of whether a resource to be used for an uplink control channel in the unlicensed spectrum is a fixed resource, a floating resource, or an adaptive resource. The UE may identify the resource based at least in part on the control channel resource configuration. The UE may transmit uplink control information on the identified resource. Numerous other aspects are provided.

Abstract: A user equipment (UE) may employ an extended cyclic prefix, a postfix, or both for sounding reference signal (SRS) transmissions, such that gaps between SRS transmissions are long enough for UE antenna switching operations (e.g., based on antenna switching capabilities of the UE), but shorter in duration than any maximum channel vacancy time durations set by a wireless communications system. Further, UEs may transmit SRSs to base stations in accordance with an SRS configuration. For example, a base station may provide SRS configuration information to a UE that indicates, for example, information related to SRS scheduling, subband information, a cyclic prefix length, a cyclic postfix length, listen-before-talk (LBT) type information, an SRS trigger, an SRS cancellation procedure, or any combinations thereof. Based on such SRS configuration information, a UE may perform partial subband SRS techniques, subband selection techniques, SRS bandwidth adaptation techniques, LBT type configuration techniques, etc.

Abstract: Techniques and devices for wireless communications are described that provide for staggering sounding reference signal (SRS) transmissions in frequency across multiple orthogonal frequency division multiplexing (OFDM) symbols, which may allow multiple UEs to transmit SRS using a common listen-before-talk (LBT) gap for a LBT procedure. The techniques also provide for transmitting an SRS across multiple OFDM symbols using same frequency resources, and an orthogonal cover code (OCC) may be applied to the SRS transmission of each OFDM symbol, which may allow multiple UEs to transmit concurrent SRS using a common LBT gap.

Abstract: Certain aspects of the present disclosure provide techniques for enhanced physical uplink control channel (PUCCH) transmission. In some cases, a UE obtains payload bits to be conveyed in a physical uplink control channel (PUCCH) transmission via an interlace of resource blocks (RBs), determines a group of the RBs available to the UE, and transmits the payload bits using the determined group of RBs, wherein the transmitting involves modulating different RBs of the group by at least one of different payload bits or sequences.

Abstract: Methods, systems, and devices for wireless communications are described. A user equipment (UE) may receive a set of one or more uplink grants scheduling at least a first uplink transmission and a second uplink transmission during a channel occupancy time of an unlicensed radio frequency spectrum band. The UE may identify a transmission gap between the first uplink transmission and the second uplink transmission of the plurality of uplink transmissions by the UE during the channel occupancy time, the transmission gap exceeding a threshold time. The UE may determine that the transmission gap corresponds to a lost uplink grant. The UE may modify the first uplink transmission or the second uplink transmission based at least in part on the determination that the transmission gap corresponds to the lost uplink grant.

Abstract: Enhanced transmission opportunities are disclosed for sounding reference signals (SRS). The enhancements may provide more flexibility in scheduling SRS transmission and more SRS transmission opportunities. An additional offset may be defined and dynamically communicated to a user equipment (UE) to use either to override or in additional to a semi-statically communicated standard offset when scheduling the SRS transmission opportunity based on an SRS trigger slot or another granted slot. The UE may further treat each combination of timing information as a separate SRS opportunity or may define a window between two signaled timing offsets within which the UE may attempt SRS transmissions.

Abstract: This disclosure provides systems, methods, and apparatuses for random access channel (RACH) occasions that overlap each other in time and frequency. In one aspect, the RACH occasions may use different preamble sequence sets. A base station may signal configuration information indicating the preamble sequence sets for the RACH occasions and information indicating a time-frequency resource allocation of the RACH occasions. A UE may perform a random access procedure in accordance with the configuration information.

Abstract: Methods, systems, and devices for wireless communications are described for managing sounding reference signal (SRS) transmissions in shared radio frequency spectrum. Described techniques provide for increased occasions at which a SRS may be transmitted, enhance likelihood of a successful listen-before-talk (LBT) procedure, or any combinations thereof. Increased occasions for SRS may be provided through multiple transmission times that are available in the event of an earlier LBT failure. Enhanced likelihood of successful LBT may be provided through one or more timing offsets that may be randomly selected from a set of available timing offsets, selection of a cyclic prefix length for a SRS based on whether the SRS transmission is within or outside of a channel occupancy time of a base station, providing an initial SRS transmission time for an initial periodic time interval, triggering of an aperiodic SRS within the channel occupancy time, or any combinations thereof.

Abstract: Techniques and devices for wireless communications are described that provide for staggering sounding reference signal (SRS) transmissions in frequency across multiple orthogonal frequency division multiplexing (OFDM) symbols, which may allow multiple UEs to transmit SRS using a common listen-before-talk (LBT) gap for a LBT procedure. The techniques also provide for transmitting an SRS across multiple OFDM symbols using same frequency resources, and an orthogonal cover code (OCC) may be applied to the SRS transmission of each OFDM symbol, which may allow multiple UEs to transmit concurrent SRS using a common LBT gap.

Abstract: This disclosure provides systems, methods, and apparatus, including computer programs encoded on computer storage media, for group reference signal triggering for contention-based systems. The described techniques may enable a network node to trigger a group of one or more user equipments (UEs) to transmit a reference signal to the network node. The network node may transmit a group common control channel indicating timing information or configuration information corresponding to a set of resources for the transmission of the reference signal. The one or more UEs may transmit the reference signal according to the timing information or configuration information.