Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive downlink control information (DCI) that includes an indication of a null resource element pattern. The null resource element pattern may be indicated in the DCI using: a value of an antenna port field that also indicates one or more demodulation reference signal (DMRS) ports for the UE and a number of DMRS code-division multiplexing groups without data, or one or more zero power downlink reference signals. The UE may perform one or more demodulation interference measurements based at least in part on the null resource element pattern. The UE may demodulate a downlink communication based at least in part on performing the one or more demodulation interference measurements. Numerous other aspects are provided.

Abstract: An apparatus for wireless communication transmits a demodulation reference signal (DMRS) for at least eight orthogonal DMRS ports in a single symbol of at least one slot. The apparatus also transmits data in the at least one slot. The apparatus may correspond to a base station transmitting DMRS and downlink data. The apparatus may correspond to a user equipment (UE) transmitting DMRS and uplink data. The apparatus may bundle the DMRS across multiple slots with a bundled DMRS including a first set of the DMRS ports in a first single symbol of a first slot and a second set of the DMRS ports in a second single symbol of a second slot. The apparatus may transmit the DMRS in only a single slot in a physical resource block group (PRG) including two or more resource blocks using four frequency domain orthogonal cover codes (FD-OCC) and a frequency offset pattern.

Abstract: Disclosed are techniques for wireless positioning. In an aspect, a reduced-capability user equipment (UE) receives, from each of one or more premium UEs, one or more parameters indicating a quality of a location estimate of the premium UE, selects at least one premium UE based on the quality of the location estimate of the at least one premium UE, and derives a location estimate of the reduced-capability UE based on the location estimate of the at least one premium UE. In another aspect, a reduced-capability UE transmits, to at least one premium UE, a request to perform one or more positioning measurements of one or more downlink reference signals, receives, from the at least one premium UE, a measurement report comprising the one or more positioning measurements, and determines a location estimate of the reduced-capability UE based on the one or more positioning measurements in the measurement report.

Abstract: In an aspect, a UE estimates channel state(s) of channels(s) between the UE and network node(s) based on DL RS(s) for positioning that are scheduled and transmitted on DL resources from network node(s). The UE may apply TR filter(s) derived based on the estimated channel state(s) to a UL-RS for positioning. The UE may transmit the TR filtered UL-RS on UL resources which are associated with the DL resources of the DL-RS(s) and which are scheduled by the network node(s). The association between the UL resources and the DL resources may be indicated to the UE by the network node(s).

Abstract: Methods, systems, and devices for wireless communications are described. A user equipment (UE) may be configured to estimate a signal-to-noise ratio for each antenna port associated with a reception of one or more tracking reference signals. The UE may receive one or more of multiple single-port tracking reference signals, a single multi-port tracking reference signal, or a tracking reference signal associated with multiple power ratios. The UE may be able to estimate a channel upon receiving a demodulation reference signal. The channel estimation may be based on the reception of one or more of multiple single-port tracking reference signals, the single multi-port tracking reference signal, or the tracking reference signal associated with multiple power ratios. The UE may communicate with the base station based on estimating the channel.

Abstract: Aspects of the present disclosure include methods for communication using a MIMO channel, such as an acoustic channel for underwater communication. An acoustic receiver may receive a signal comprising information encoded in at least one transmitted symbol. Using a two-layer iterative process, the at least one transmitted symbol is estimated. The first layer of the two-layer process uses iterative exchanges of soft-decisions between an adaptive turbo equalizer and a MAP decoder. The second layer of the two-layer process uses a data-reuse procedure that adapts an equalizer vector of both a feedforward filter and a serial interference cancellation filter of the adaptive turbo equalizer using a posteriori soft decisions of the at least one transmitted symbol. After a plurality of iterations, a hard decision of the bits encoded on the at least one transmitted symbol is output from the MAP decoder.

Abstract: Systems and methods for underwater communication using a MIMO acoustic channel. An acoustic receiver may receive a signal comprising information encoded in at least one transmitted symbol. Using a two-layer iterative process, the at least one transmitted symbol is estimated. The first layer of the two-layer process uses iterative exchanges of soft-decisions between an adaptive turbo equalizer and a MAP decoder. The second layer of the two-layer process uses a data-reuse procedure that adapts an equalizer vector of both a feedforward filter and a serial interference cancellation filter of the adaptive turbo equalizer using a posteriori soft decisions of the at least one transmitted symbol. After a plurality of iterations, a hard decision of the bits encoded on the at least one transmitted symbol is output from the MAP decoder.

Abstract: Systems and methods for underwater communication using a MIMO acoustic channel. An acoustic receiver may receive a signal comprising information encoded in at least one transmitted symbol. Using a two-layer iterative process, the at least one transmitted symbol is estimated. The first layer of the two-layer process uses iterative exchanges of soft-decisions between an adaptive turbo equalizer and a MAP decoder. The second layer of the two-layer process uses a data-reuse procedure that adapts an equalizer vector of both a feedforward filter and a serial interference cancellation filter of the adaptive turbo equalizer using a posteriori soft decisions of the at least one transmitted symbol. After a plurality of iterations, a hard decision of the bits encoded on the at least one transmitted symbol is output from the MAP decoder.

Abstract: Systems and methods for underwater communication using a SISO acoustic channel. An acoustic receiver may receive a signal comprising information encoded in at least one transmitted symbol. Using a Bi-SDFE, the at least one transmitted symbol is estimated. The Bi-SDFE may include a SDFE and a time-reversed SDFE that each output bit extrinsic LLRs, which are combined into combined bit extrinsic LLRs. The estimated symbol is then mapped to the combined bit extrinsic LLRs, the result of which is de-interleaved. Iterative bit extrinsic LLRs are generated with a MAP and/or soft-decision decoder using the mapped, combined bit extrinsic LLRs as a priori LLRs for the Bi-SDFE in another iterative estimation. The iterative bit extrinsic LLRs are interleaved and transmitted for use by the Bi-SDFE in another iterative estimation. After a plurality of iterations, a hard decision of the transmitted symbol is generated with the MAP and/or soft-decision decoder.