Abstract: Methods, systems, and devices for wireless communications are described. The described techniques relate to improved methods, systems, devices, and apparatuses that support chained sidelink transmissions. A transmitting user equipment (UE) may send, to a receiving UE, sidelink control information (SCI) that reserves resources for transmission from the transmitting UE as well as reserves resources for a response transmission from the receiving UE. The receiving UE may respond with a transmission using the resources that were reserved in the SCI and without sending its own SCI to reserve resources for the response. The latency between the transmitting UE sending the first transmission and receiving a response from the receiving UE may be reduced, because the transmitting UE reserved the resources for itself and the receiving UE with the same SCI.

Abstract: Techniques for transmitting and receiving wireless communications over an unlicensed radio frequency spectrum band are disclosed, including techniques for transmitting and receiving service 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 communicating locations of reference signals, and techniques for communicating availability of certain resources to be combined across multiple different transmissions.

Abstract: Methods, systems, and devices for wireless communication are described. A wireless device may perform a listen before talk (LBT) procedure on a channel bandwidth using an energy detection (ED) threshold. The ED threshold being associated with a transmission bandwidth that is narrower than the channel bandwidth. The wireless device may also, responsive to a successful LBT procedure, transmit on the transmission bandwidth according to a frequency hopping pattern during a first channel occupancy time (COT). The frequency hopping pattern comprises a first resource allocation and a second resource allocation different from the first resource allocation.

Abstract: Methods, systems, and devices are described for reference signal design in wireless communications. A base station may select a reference signal density scheme from a set of available density schemes associated with a port count. The reference signal density scheme may also be selected based on the category of the mobile device receiving the reference signal transmissions. The reference signal density scheme may be a higher density reference signal density scheme or a lower density reference signal density scheme, where the higher density reference signal density scheme includes more reference signal resource elements per subframe. The mobile device may determine the reference signal density scheme based on characteristics of a channel. The higher density reference signal density scheme may provide additional channel estimation opportunities for the mobile device. In some cases, the mobile device sends the channel estimated based on the received reference signals to the base station.

Abstract: Wireless communications systems and methods related to autonomous sidelink communication in a radio frequency band (e.g., in a shared spectrum or an unlicensed spectrum) shared by multiple network operating entities are provided. A first user equipment (UE) performs a listen-before-talk (LBT) in a shared radio frequency band based on a first starting point of a plurality of starting points within an LBT gap duration. The first UE transmits, to a second UE, a first sidelink communication in the shared radio frequency band based on the LBT, the first sidelink communication including first sidelink control information (SCI) and first sidelink data.

Abstract: Methods, systems, and devices for wireless communications are described. A base station may identify a listen-before-talk (LBT) procedure to use for transmitting a downlink signal to a user equipment (UE) on a shared radio frequency spectrum band. The LBT procedure may be a group LBT procedure associated with a first set of contention window durations or an individual listen-before talk procedure associated with a second set of contention window durations. The base station may determine a contention window duration corresponding to the identified LBT procedure, perform the identified LBT procedure using the determined contention window duration, and transmit the downlink signal to the UE based on the performed LBT procedure.

Abstract: This disclosure provides systems, methods and apparatus, including computer programs encoded on computer storage media, for narrowband communications using frequency hopping in an unlicensed frequency band. In some implementations, a base station (BS) may transmit downlink (DL) data using a sequence of DL hopping frames on a corresponding sequence of unique hopping channels associated with a DL frequency hopping pattern. In some implementations, each user equipment (UE) of one or more UEs may transmit uplink (UL) data using a sequence of UL hopping frames on a corresponding sequence of unique hopping channels associated with a different UL frequency hopping pattern.

Abstract: Certain aspects of the present disclosure provide techniques for reuse one channel access for new radio communications in unlicensed spectrum. A method that may be performed by a first base station (BS) includes occupying a bandwidth, based on a category 4 (CAT4) listen before talk (LBT) procedure on the bandwidth, wherein the CAT4 LBT procedure is based on a first contention window (CW); arranging a category 2 (CAT2) LBT occasion for the bandwidth during a channel occupancy time (COT) for the bandwidth; and receiving an indication that at least a second BS has occupied the bandwidth during the CAT2 LBT occasion.

Abstract: Methods, systems, and devices are described for low latency communications within a wireless communications system. An eNB and/or a UE may be configured to operate within the wireless communications system and may send triggers to initiate communications using a dedicated resource in a wireless communications network that supports transmissions having a first subframe type and a second subframe type, the first subframe type comprising symbols of a first duration and the second subframe type comprising symbols of a second duration that is shorter than the first duration. Communications may be initiated by transmitting a trigger from the UE or eNB using the dedicated resource, and initiating communications following the trigger. The duration of time between the trigger and initiating communications can be significantly shorter than the time to initiate communications using legacy LTE communications.

Abstract: Wireless communications systems and methods related to automatic frequency coordination (AFC) for spectrum sharing among multiple network operating entities are provided. A first wireless communication device transmits, to a spectrum access coordination entity, a spectrum access request. The first wireless communication device receives, from the spectrum access coordination entity in response to the spectrum access request, a configuration including at least a medium access protocol parameter for performing a medium access procedure in a spectrum shared by a plurality of network operating entities.

Abstract: Methods, systems, and devices are described for hierarchical communications and low latency support within a wireless communications system. An eNB and/or a UE may be configured to operate within the wireless communications system which is at least partially defined through a first layer with first layer transmissions having a first subframe type and a second layer with second layer transmissions having a second subframe type. The first subframe type may have a first round trip time (RTT) between transmission and acknowledgment of receipt of the transmission, and the second layer may have a second RTT that is less than the first RTT. Subframes of the first subframe type may be multiplexed with subframes of the second subframe type, such as through time division multiplexing. In some examples symbols of different duration may be multiplexed such that they different symbol durations coexist.

Abstract: Cell acquisition is disclosed in frequency diversity configured for frame based equipment (FBE) access, such as using opportunistic frequency switching. A user equipment (UE) begins cell acquisition by synchronizing to an available communication channel of an available cell in response to detection of a synchronization signal block (SSB) associated with a network on which the UE communicates. The UE receives system information associated with the available cell from a serving base station, wherein the system information includes identification of at least: a link indicator identifying linked communication channels available for opportunistic switching, sensing occasion offsets for each of the linked channels, and access information associated with each of the linked channels. The UE measures a channel quality for each available channel. The base station transmits this system information on each of the linked channels and then monitors the allocated random access resources for signals from the UEs.

Abstract: Certain aspects of the present disclosure provide techniques for qualifying machine learning model-based channel state information (CSI) predictions. An example method generally includes receiving, from a network entity, a channel state information (CSI) prediction model for quantized CSI, calculating CSI based on downlink reference signal measurements, generating a quantized CSI difference value based a quantization of a difference between the calculated CSI and CSI predicted based on a CSI prediction model, and reporting, to the network entity, the calculated CSI and the quantized CSI difference value.

Abstract: Wireless communications systems and methods related to autonomous sidelink communication in a shared radio frequency band (e.g., in a shared spectrum or an unlicensed spectrum) are provided. A first user equipment (UE) performs a listen-before-talk (LBT) in a shared radio frequency band during at least a portion of a first sidelink frame. The first UE determines a channel occupancy time (COT) in the shared radio frequency band based on the LBT. A beginning of the COT is within the first sidelink frame and offset from a boundary of the first sidelink frame. The COT includes one or more sidelink frames subsequent to the first sidelink frame. The first UE transmits, in the shared radio frequency band, a COT indication signal at the beginning of the COT within the first sidelink frame. The COT indication signal includes COT sharing information for UEs to share the one or more sidelink frames.

Abstract: Wireless communications systems and methods related to autonomous sidelink communication are provided. A first user equipment (UE) communicates, in a first subband of a plurality of subbands within a shared radio frequency band during a first time period, first sidelink control information (SCI) associated with a second subband of the plurality of subbands. The first UE communicates, with the second UE, first sidelink data in the second subband during the first time period based on the first SCI. The first UE communicates, with the second UE in the first subband during a second time period, second SCI associated with a third subband of the plurality of subbands, the third subband being different from the second subband based on a frequency hopping pattern. The first UE communicates, with the second UE, second sidelink data in the third subband during the second time period based on the second SCI.

Abstract: Methods, systems, and devices for wireless communications are described. A base station may configure a user equipment (UE) with a multiple listen-before-talk (LBT) bandwidths, where each LBT bandwidth is associated with one or more downlink control channel candidates of a search space for a control resource set. The UE may monitor the LBT bandwidths during a wakeup signal period for a wakeup signal from the base station. The UE may be configured with a total number of blind hypotheses in the set of blind hypotheses which is equal to or greater than a total number of LBT bandwidths. The UE may determine whether to wake up and monitor an on duration of a discontinuous reception cycle based on detection of the wakeup signal.

Abstract: This disclosure provides systems, methods and apparatuses for wireless communication that may allow a user equipment (UE) to determine its relative position and distances to other UEs more accurately than standard vehicle-to-everything (V2X) communications allow. In some implementations, a UE (or other wireless communication device) participating in a positioning operation may transmit and receive positioning signals on an unlicensed radio band, and may transmit and receive non-positioning signals on a V2X channel (or on another suitable channel) of a radio access network (RAN). The positioning signals may include positioning reference signals (PRSs) associated with observed time difference of arrival (OTDOA) positioning operations, ranging signals associated with round-trip time (RTT) positioning operations, or other suitable signals from which the position of the UE can be determined.

Abstract: Methods and apparatuses are described for wireless communications. A first method includes transmitting a first Orthogonal Frequency-Division Multiple Access (OFDMA) communications signal to a wireless node in a licensed spectrum, and transmitting, concurrently with the transmission of the first OFDMA communications signal, a second OFDMA communications signal to the wireless node in an unlicensed spectrum. A second method includes receiving a first Orthogonal Frequency-Division Multiple Access (OFDMA) communications signal from a wireless node in a licensed spectrum, and receiving, concurrently with the reception of the first OFDMA communications signal, a second OFDMA communication signal from the wireless node in an unlicensed spectrum.

Abstract: Methods and apparatuses are described in which an unlicensed spectrum is used for Long Term Evolution (LTE) communications. One method includes performing a clear channel assessment (CCA) for an unlicensed spectrum in a current gating interval to determine whether the unlicensed spectrum is available for a transmission in a next transmission interval, and gating OFF the transmission in the unlicensed spectrum for the next transmission interval when the determination is that the unlicensed spectrum is unavailable.

Abstract: Wireless communications systems and methods related to channel access with variable energy detection thresholds in a shared radio frequency band are provided. A wireless communication device, performs a listen-before-talk (LBT) procedure to contend for a maximum channel occupancy time (MCOT) in a first shared radio frequency band, the performing the LBT including performing, in the first shared radio frequency band, first channel sensing during a first portion of an LBT period based on a first energy detection threshold; and performing, in the first shared radio frequency band based on the first channel sensing, second channel sensing during a second portion of the LBT period based on a second energy detection threshold different from the first energy detection threshold; and communicating, in the first shared radio frequency band, a communication signal during the MCOT based on the LBT procedure.