Abstract: Methods, systems, devices, and apparatuses are described for wireless communications. In one method, a set of one or more data subframes of a data frame may be transmitted over an unlicensed spectrum, to a user equipment (UE), during a transmission period. A group hybrid automatic repeat request (HARQ) feedback message for a plurality of data subframes including at least one of the data subframes in the set of one or more data subframes may then be received over the unlicensed spectrum, from the UE, during the transmission period. In another method, a set of one or more data subframes of a data frame may be received over an unlicensed spectrum during a transmission period. A group HARQ feedback message for a plurality of data subframes including at least one of the data subframes in the set of one or more data subframes may then be transmitted over the unlicensed spectrum during the transmission period.

Abstract: This disclosure describes methods, devices, and systems for techniques related to random access channel (RACH) operation. A user equipment (UE) may establish a connection with a base station using a random access procedure. Based on a transmission priority or a network parameter, the random access procedure may be a two-step random access procedure or a four-step random access procedure. The described techniques may support physical layer procedures, including resource configurations and communication schemes that may support enhanced signaling capacity. In some examples, the described techniques may include signaling characteristics and resource mappings for two-step random access procedure based on a transmission priority. In other examples, the described techniques may include antenna techniques associated with a four-step random access procedure.

Abstract: New radio (NR) transmission opportunity (TxOP) structure having flexible starting points are disclosed for wireless communications. When a typical listen before talk (LBT) procedure is performed, the transmitting node will not know ahead of time when the LBT will pass and, thus, when data transmissions can start. NR systems may include a mini-slot design for accommodating transmission units smaller than a slot. Aspects of the present disclosure provide for flexibly increasing the number of potential starting transmission boundaries depending on when the LBT pass is detected. Alternative aspects of the present disclosure determine the potential starting transmission points using a mini-slot based design, a floating slot based design, or a punctured slot based design with a code block group (CBG) level retransmission mechanism.

Abstract: Methods, systems, and devices for wireless communication are described. Discontinuous reception (DRX) operation may be configured differently on enhanced component carriers (eCCs) than on other component carriers, including a primary cell (PCell). In some cases, a user equipment (UE) may be configured with several different eCC DRX modes. An eCC DRX configuration may, for example, be coordinated with downlink (DL) transmission time interval (TTI) scheduling so each DRX ON duration may correspond to a DL burst duration of the corresponding eCC. The eCC DRX ON durations may also be scheduled according to hybrid automatic repeat request (HARQ) process scheduling. In some examples, eCC DRX ON durations may be based on listen-before-talk (LBT) procedures. In some cases, eCC DRX ON durations may be configured to contain an uplink (UL) burst to enable channel state information (CSI) reporting. The eCC DRX may also be configured to minimize interruption of the PCell.

Abstract: Methods, systems, and devices for wireless communication are described. A base station may employ a multiplexing configuration based on latency and efficiency considerations. The base station may transmit a resource grant, a signal indicating the length of a downlink (DL) transmission time interval (TTI), and a signal indicating the length of a subsequent uplink (UL) TTI to one or more user equipment (UEs). The base station may dynamically select a new multiplexing configuration by, for example, setting the length of an UL TTI to zero or assigning multiple UEs resources in the same DL TTI. Latency may also be reduced by employing block feedback, such as block hybrid automatic repeat request (HARQ) feedback. A UE may determine and transmit HARQ feedback for each transport block (TB) of a set of TBs, which may be based on a time duration of a downlink TTI.

Abstract: A method, apparatus, and computer-readable medium that enable and disable autonomous downlink transmission (ADT) capability at a user equipment (UE) or a gNB are disclosed. The ADT capability is enabled when a triggering event occurs. The ADT capability is realized in part via initiating a listen before talk (LBT) procedure of a first LBT type to obtain an uplink (UL) transmission opportunity (TxOP) after determining that the UE does not have any UL data to transmit, transmitting uplink control information (UCI) with a limited amount of data to request for a resource grant of the TxOP for pending DL data; and receiving the pending DL data, wherein resources for receiving the pending DL data is dynamically configured via the UCI or semi-statically configured through a radio resource control (RRC) protocol message.

Abstract: Systems and methods facilitating feedback of robust channel state information (CSI), such as to provide full CSI feedback or otherwise providing CSI feedback, are described. CSI encoders and/or decoders used by network nodes may implement channel compression/reconstruction based upon neural-network (NN) training of collected channels. A structured payload having an interpretable payload portion and an uninterpretable payload portion may utilized with respect to CSI feedback. The channel compression provided according to some aspects of the disclosure supports feedback of robust CSI, in some instances including full CSI, as determined by a particular network node. Other aspects and features are also claimed and described.

Abstract: Methods, systems, and devices for wireless communications are described. A transmitter may identify a contention window for a no-energy-detection protocol for determining a channel availability for a data transmission. After the contention window expires, the transmitter may send a request message to a receiver. The receiver may measure a quality of the request message against a request threshold and transmit a response message if the measured quality exceeds the request threshold. The transmitter may then measure a quality of the response message against a response threshold. If the measured quality exceeds the response threshold, the transmitter may initiate a data transmission with the receiver. If the quality falls below the response threshold or the response message is not received, the transmitter may adjust the contention window and reattempt the no-energy-detection protocol. The contention window may also be adjusted based on an acknowledgement message received after the data transmission.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a node may receive a configuration associated with measuring an energy level of a first frequency channel of an unlicensed radio frequency band, wherein the configuration indicates a set of measurement occasions during which the energy level is to be measured on the first frequency channel; measure the energy level on the first frequency channel in a first measurement occasion, of the set of measurement occasions, according to the configuration; and operate in association with a second frequency channel of the unlicensed radio frequency band based at least in part on measuring the energy level on the first frequency channel, wherein the second frequency channel is paired with the first frequency channel for the unlicensed radio frequency band. Numerous other aspects are provided.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a node may identify a listen-before-talk (LBT) success time at which an LBT procedure, performed by the node, succeeds; determine a lag between the LBT success time and a most recent synchronization reference boundary that occurred prior to the LBT success time; and determine a maximum channel occupancy time for transmissions on an unlicensed radio frequency spectrum band based at least in part on comparing the lag and a threshold. Numerous other aspects are provided.

Abstract: Certain aspects of the disclosure relate to performing cross-subframe control channel signaling for wireless communications. A method may be provided for signaling downlink control channel resource allocations and/or physical control format indications in a subframe different from the subframe in which a downlink data transmission may be performed. In one aspect, the method may include transmitting PDCCH and/or PCFICH during a first subframe to allocate resources for a PDSCH during a second subframe and transmitting the PDSCH during the second subframe.

Abstract: A method of wireless communication includes determining, by a user equipment (UE) in response to a failed transmission to the UE by a base station, to transmit a negative acknowledgment (NACK). The method additionally includes transmitting, by the UE to the base station, the NACK in an acknowledgement (ACK) resource previously allocated by the base station, and triggering at least one action, by the UE in response to at least one of the determination to transmit the NACK or the transmission of the NACK. The at least one action improves retransmission success rate. In another aspect, a method of wireless communication includes receiving, by a base station from a UE, a NACK in an ACK resource previously allocated by the base station, and triggering at least one action, by the base station in response to the receipt of the NACK. The at least one action improves retransmission success rate.

Abstract: Techniques are described for wireless communication. One method includes winning a contention for access to an unlicensed radio frequency spectrum band, transmitting a request message upon winning the contention for access to the unlicensed radio frequency spectrum band, and receiving a response message over the unlicensed radio frequency spectrum band. The request message is transmitted by a user equipment (UE) on an enhanced physical random access channel (ePRACH), to access a cell that operates in the unlicensed radio frequency spectrum band. The response message is received in response to transmitting the request message.

Abstract: Uplink clear channel assessment (CCA) status is disclosed as a new uplink control message for new radio (NR) unlicensed (NR-U) operations. When an opportunity for potential uplink transmissions arises for a user equipment (UE), the UE will perform a CCA procedure on available uplink resources. The UE reports the results of the CCA procedure to a serving base station via an uplink control message, such as an uplink control information (UCI), physical uplink control channel (PUCCH), or the like. The serving base station may then use the CCA results in scheduling uplink transmissions and reserving uplink resources.

Abstract: Techniques are described for wireless communication. A first method includes transmitting a first signal to indicate accessing a first channel in a radio frequency spectrum band, and transmitting information with the first signal in the radio frequency spectrum band. A second method includes winning contention to access a radio frequency spectrum band, and after the winning contention to access the radio frequency spectrum band, transmitting a first signal to align a starting point of a second signal with a reference boundary associated with the radio frequency spectrum band. A third method includes winning contention to access a radio frequency spectrum band during a first frame period, the first frame selected from a plurality of different frame periods, and transmitting a signal at a periodicity during one or more subframes of the first frame period for each of the plurality of different frame periods.

Abstract: Aligned listen before talk (LBT) gaps for single operator frame-based equipment (FBE) mode new radio (NR) shared spectrum (NR-SS) is disclosed. Within the FBE mode network, the base station determines a plurality of potential transmission bursts within a fixed frame period. The base station may then reserve a plurality of LBT gaps prior to the starting position of each such transmission burst. The base station communicates the location of each of the LBT gaps to all neighboring network entities and contends for access to the fixed frame period at the beginning of the frame regardless of whether it has data for transmission during the frame. Each neighboring base station that receives the LBT gaps locations will use the same locations in order to align the LBT gaps over the FBE mode network.

Abstract: Autonomous uplink (AUL) for wideband new radio (NR) unlicensed (NR-U) operations is disclosed. For user equipments (UEs) that have been configured for AUL transmissions and have received an activation signal to activate the AUL capabilities, further indications may be used to enable AUL transmissions on AUL transmission opportunities (TxOPs) that overlap the timing of a current TxOP reserved by a serving base station, but that are allocated outside of the resources reserved for the current TxOP. A UE that identifies a desired, next AUL TxOP that overlaps the current base station-initiated TxOP duration, but is allocated for resources outside of the current TxOP resources determines whether it has obtained an enablement indication either directly from the serving base station or implicitly, based on current conditions at the UE. When the UE determines that it has obtained an enabling indication, it may then perform AUL transmissions via the overlapping AUL TxOP.

Abstract: Techniques for transmitting and receiving wireless communications over an unlicensed radio frequency spectrum band are disclosed, including techniques for transmitting and receiving system information blocks over the unlicensed radio frequency spectrum band, techniques for gaining access to the unlicensed radio frequency spectrum band by performing extended clear channel assessments (ECCAs), techniques for transmitting and receiving synchronization signals and reference signals over the unlicensed radio frequency spectrum band, techniques for identifying starting times of downlink transmissions over the unlicensed radio frequency spectrum band, techniques for transmitting and receiving clear channel assessment (CCA)-exempt transmissions over the unlicensed radio frequency spectrum band, techniques for performing random access over the unlicensed radio frequency spectrum band, and techniques for dynamically modifying a transmission mode over the unlicensed radio frequency spectrum band.

Abstract: Methods, systems, and devices for wireless communications are described. A user equipment (UE) may identify that the UE is configured to use a two-step random access channel (RACH) procedure. The two-step RACH procedure may include an uplink request message and a downlink response. The UE may transmit the uplink request message as part of the two-step RACH procedure, and the uplink request message may include a preamble portion that is one of a set of predefined sequences and a payload portion that includes a physical uplink shared channel waveform. The UE may receive the downlink response as part of the two-step RACH procedure and in response to the uplink request message.

Abstract: Techniques are described for wireless communication. A first method includes generating uplink control information at a wireless device, and transmitting the uplink control information over an interlace of a component carrier of an unlicensed radio frequency spectrum band. The interlace includes a plurality of non-contiguous concurrent resource blocks in the unlicensed radio frequency spectrum band, and at least two resource blocks in the interlace include different portions of the uplink control information. A second method includes generating uplink control information at a wireless device, and transmitting the uplink control information over an uplink control channel of an unlicensed radio frequency spectrum band. Resources of the uplink control channel are divided into a plurality of discrete dimensions and the uplink control information of the wireless device is transmitted over a number of the discrete dimensions allocated to the uplink control information of the wireless device.