Abstract: Methods, systems, and devices for wireless communications are described. In a wireless communications system, a base station may support a flexible cell with a set of carriers including an anchor carrier and two or more non-anchor carriers. In some examples, a user equipment (UE) may select, from among the set of carriers and based on receiving an indication of the configuration, a carrier for transmission of a request for system information associated with the flexible cell. The UE may transmit the request for system information to the base station via the selected carrier. Additionally or alternatively, the UE may select a carrier for reception by the UE of an acknowledgement for the request for the system information, and the UE may receive the acknowledgement for the request for system information via the selected carrier.

Abstract: Methods, systems, and devices for scrambling for probabilistic constellation schemes (PCSs) in wireless communications are described. In some examples, a first wireless device may scramble a set of amplitude information bits associated with a transport block for transmission to a second wireless device. In such examples, the first wireless device may perform a distribution matching procedure on the scrambled set of amplitude information bits. The first wireless device may encode the set of distributed amplitude bits and, in some cases, may perform a modulation procedure on the encoded set of distributed amplitude bits in accordance with a PCS scheme to obtain a codeword associated with the transport block. In some examples, the first wireless device may transmit the codeword to the second wireless device.

Abstract: Methods, systems, and devices for wireless communications are described. A user equipment (UE) may receive, from a base station, first control signaling configuring multiple aperiodic channel state information (A-CSI) trigger states including at least a first trigger state for a first power mode and a second trigger state for a second power mode. The UE may receive second control signaling indicating a trigger state of the multiple A-CSI trigger states. The UE may determine a current power mode of the network based on the indicated trigger state. In some examples, the UE may receive third control signaling indicating a subset of the multiple A-CSI trigger states, and the second control signaling may indicate one trigger state from the subset of A-CSI trigger states. The UE may transmit a channel state information (CSI) report based on the indicated trigger state and the current power mode of the network.

Abstract: Methods, systems, and devices for wireless communication are described. A user equipment (UE) may transmit, from a UE to a base station, one or more reference signals over a channel. The UE may receive, from the base station based at least in part on transmitting the one or more reference signals, control signaling indicating a precoding matrix indicator (PMI) and a rank indicator (RI) based at least in part on the UE having at least eight transmit antennas and based at least in part on a phase difference between different subsets of transmit antennas of the at least eight transmit antennas. The UE may transmit, to the base station, an uplink transmission configured according to the PMI and the RI.

Abstract: Method and apparatus for carrier selection for paging on a flexible cell. The apparatus receives an indication to monitor at least one carrier from a flexible cell for a paging message. The flexible cell comprising an anchor carrier and one or more non-anchor carriers. The apparatus monitors a first carrier from the flexible cell for the paging message based on the indication, the paging message associated with a PDCCH that schedules a PDSCH. The apparatus may receive, from the flexible cell, a downlink BWP configuration for the anchor carrier and the one or more non-anchor carriers.

Abstract: Methods, systems, and devices for wireless communications are described. Generally, a user equipment (UE) may communicate on first and second carriers, and may support either two transmit chains or three transmit chains on a second carrier. A base station may configure different sounding reference signal (SRS) resources for different numbers of transmit chains. SRS resources configured with two ports may indicate two transmit chains, and SRS resource configured with three ports may indicate three transmit chains. The base station may indicate an index associated with an SRS resource, and the UE may select (e.g., based on a mapping between the SRS Configuration Information resource index and a number of SRS ports and a number of transmit chains), a corresponding SRS resource, number of ports, number of transmit chains, or any combination thereof. The base station may indicate a number of transmit chains for a given SRS resource based on a PMI index.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a wireless communication device may select a codebook for a multiple-input multiple-output (MIMO) communication from among one or more codebooks that include one or more of non-coherent codebooks for 6 or 8 antennas of the wireless communication device, partially-coherent codebooks for multiple paired antennas of the 6 or 8 antennas of the wireless communication device, or full-coherent codebooks for the 6 or 8 antennas of the wireless communication device. The wireless communication device may transmit or receiving the communication using the codebook. Numerous other aspects are described.

Abstract: Methods, systems, and devices for wireless communication are described to support an indication of one or more carriers of a flexible cell to be used for reception of one or more respective downlink random access messages. A base station may indicate, via system information, a carrier for reception of a downlink control channel scheduling a second random access message. A user equipment (UE) may initiate a random access procedure by transmitting, to the base station, a first random access message. The UE may monitor for and receive the downlink control channel scheduling the second random access message via the carrier indicated in the system information. The UE may receive the second random access message via the same carrier as the associated downlink control channel, or via a different carrier that may be indicated in the system information or in the downlink control channel transmission.

Abstract: The described techniques enable repeated physical random access channel (PRACH) preamble transmissions across multiple random access occasions (ROs) using a same spatial filter. A user equipment (UE) may transmit a PRACH preamble across multiple ROs, where each RO is associated with a same synchronization signal block (SSB) or channel state information reference signal (CSI-RS). The PRACH repetitions may be transmitted in ROs in accordance with a first mapping rule: first, in increasing order of frequency resource index; second, in increasing order of a time resource index; third, in increasing order of PRACH slot indices; and fourth, in increasing order of PRACH association period indices. Additionally, or alternatively, the PRACH repetitions may be transmitted in ROs in accordance with a second mapping rule: first, in increasing order of time resource index; second, in increasing order of PRACH slot indices; and third, in increasing order of PRACH association period indices.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive signaling identifying a transmission precoding matrix indicator associated with a transmit codebook configured for three antenna ports. The UE may transmit an uplink communication in accordance with the transmit codebook configured for three antenna ports. Numerous other aspects are described.

Abstract: In a probabilistic amplitude shaping (PAS) system, a distribution matching (DM) component may receive a uniform bit sequence with equal probabilities, which may be converted into symbols with a desired probability distribution (e.g., Gaussian). For example, the probability distribution may use inner constellation points associated with a lower energy and/or power more frequently and outer constellation points associated with a higher energy and/or power less frequently. In general, the DM component may map binary bits to positive amplitudes with a non-uniform distribution according to a DM rate that is based at least in part on a signal-to-noise ratio (SNR), which may vary significantly in a spatial and frequency selective wireless channel. Accordingly, some aspects described herein relate to configuring DM parameters and codeword and resource mappings in a spatial and frequency selective wireless channel.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may transmit, to a base station, a first message of a random access procedure. The UE may receive, from the base station, a second message of the random access procedure that indicates information for an uplink grant for a third message of the random access procedure, the information including a modulation and coding scheme (MCS) indication and a transmit power control (TPC) indication. The UE may transmit, to the base station, one or more repetitions of a physical uplink shared channel carrying the third message. A repetition factor for the one or more repetitions may be indicated by at least one of the MCS indication or the TPC indication. Numerous other aspects are described.

Abstract: Certain aspects of the present disclosure provide a technique for parallel distribution matching (DM) encoding. A user equipment (UE) implements the technique to perform a first round of parallel DM encoding using k information bits as input by: 1) segmenting the k information bits into N blocks of information bits, and 2) encoding the N blocks of information bits in parallel with N DM blocks. Each of the N blocks outputs one or more encoded information bits in each of the NDM blocks, and a total number of information bits output by the N DM blocks is less than k. The UE then performs a second round of parallel DM encoding using k? information bits that were not encoded in the first round of DM encoding. The second round of parallel DM encoding includes a same encoding process as implemented in the first round of parallel DC encoding.

Abstract: This disclosure provides systems, devices, apparatus, and methods, including computer programs encoded on storage media, for responses to Msg3 PUSCH repetition requests of a UE. In a first aspect, the UE may transmit, to a base station, a request for repetitions of at least one of a PUSCH transmission or a PUSCH retransmission for a random access Msg3 and receive, from the base station, an indication to use one or more fields to determine a number of repetitions of the at least one of the PUSCH transmission or the PUSCH retransmission for the random access Msg3. In a second aspect, the transmitted request may indicate to the base station to use the one or more fields to determine the number of the repetitions of the at least one of the PUSCH transmission or the PUSCH retransmission. The UE may transmit the number of repetitions based on the transmitted indication.

Abstract: Aspects of the disclosure relate to utilizing SRS resources for various types of usages and configuring transmit power on the SRS resources. In an aspect, a user equipment (UE) may determine whether a time gap between a first sounding reference signal (SRS) resource for a first usage and a second SRS resource for a second usage in time is less than a time threshold. Further, the UE may transmit an SRS utilizing one of the first SRS resource or the second SRS resource for both the first usage and the second usage, in response to determining that the time gap is less than the time threshold.

Abstract: Methods, systems, and devices for wireless communications are described. A transmitting device may perform distribution matching on at least a first subset of a set of bits, such as the bits of transport block. The distribution matching may include a variable-to-fixed (v2f) distribution matching procedure in which a ratio between a quantity of input bits to output interim symbols for the v2f distribution matching procedure is variable. The distribution matching include evaluating, after each instance of the v2f distribution matching procedure, whether additional bits remain for distribution matching, and if so, whether to perform an additional instance of the v2f distribution matching procedure or an alternative distribution matching procedure on the remaining bits. Corresponding techniques for a receiving device are also described, including distribution dematching techniques based on a v2f distribution dematching procedure.

Abstract: Apparatus, methods, and computer-readable media for facilitating distribution matching via reversed compression are disclosed herein. An example method for wireless communication at a wireless transmitter includes decompressing a first sequence of information bits for wireless transmission to output a sequence of shaped symbols. The example method also includes compressing the sequence of shaped symbols to output a second sequence of compressed information bits. The example method also includes transmitting, to a receiver, a signal comprising the sequence of shaped symbols.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may transmit a physical random access channel (PRACH) message corresponding to a PRACH occasion, wherein the PRACH occasion comprises a dedicated PRACH occasion or one of a plurality of PRACH occasions comprising at least one shared PRACH occasion associated with a two-step random access channel (RACH) procedure and a four-step RACH procedure, wherein the PRACH message includes a request for physical uplink shared channel (PUSCH) repetition corresponding to a radio resource control (RRC) connection request message of the four-step RACH procedure. The UE may transmit at least one PUSCH repetition associated with the RRC connection request message based at least in part on the request. Numerous other aspects are described.

Abstract: Methods, systems, and devices for power backoff techniques for modulation schemes are described. A user equipment (UE) may receive an indication of a constellation distribution parameter and a modulation scheme to be used by the UE for an uplink message on an uplink channel. The UE may determine an uplink transmission power based at least in part on the indicated constellation distribution parameter and the indicated modulation scheme. The UE may transmit the uplink message using the indicated modulation scheme according to the determined uplink transmission power. In some examples, the UE may transmit a report indicating a power headroom parameter and an output power parameter based at least in part on the constellation distribution parameter.

Abstract: Methods, systems, and devices for wireless communications are described. For instance, a user equipment (UE) may receive. from a base station, control signaling for a first sounding reference signal. The UE may determine, based on the configuration and a set of parameters associated with partial frequency sounding of the first sounding reference signal, a subset of a set of re sources configured for the first sounding reference signal, where the subset of the set of resources excludes at least one resource of the set of resources. The UE may transmit, to the base station, a second sounding reference signal over the subset of the set of resources.