Abstract: Methods, systems, and devices for wireless communications are described. In some systems (e.g., non-orthogonal multiple access (NOMA) systems), a base station may serve a large number of user equipments (UEs) on the uplink. To improve detectability for these uplink transmissions (e.g., if reference signals are not available for the transmissions), the UEs may implement parallel transmissions of preambles with uplink data. A UE may split the uplink data into one or more data layers, and may select one or more preamble layers to transmit superposed with the data layers. These preambles may be sequences known to both the UE and the base station to aid in detectability. The UE may assign different signature sequences to each of these layers based on cross-correlation values (e.g., assigning sequences with higher cross-correlation values to the data layers for improved detectability), and may scramble the layers into a single shared signal for transmission.

Abstract: Methods, systems, and devices for wireless communication are described to estimate interference for concurrent uplink and downlink communications based on an indication of one or more one or more characteristics of an interfering uplink signal communicated between a base station and a second user equipment (UE). The base station or the second UE may transmit, to a first UE, an indication of one or more characteristics of an uplink signal, such as a baseband of the uplink signal or one or more parameters of the uplink signal. The first UE may use the characteristic(s) of the uplink signal to estimate the baseband of the uplink signal and cancel interference associated with the uplink signal. For example, the first UE may use the baseband signal to estimate the interference and may subtract the estimated interference from a downlink signal received at the first UE.

Abstract: Methods, systems, and devices for wireless communications are described. Pre-discrete Fourier transform (DFT) time-domain spreading codes may be applied for UE multiplexing for uplink control information (e.g., over shared resources of an uplink slot). For example, a moderate number of UEs may be multiplexed within the same slot by having each UE spread modulation symbols before DFT-spreading by different spreading code. For orthogonality across UEs, the pre-DFT spreading codes may be selected as orthogonal cover codes (OCCs). The spreading sequences can be generated from a set of any orthogonal sequences or generated from unitary matrices. In some cases, orthogonality in the time domain may be kept as well as a frequency division multiplexed (FDM) structure in the frequency domain. For such property, a Fourier basis OCC design may be used. In some other examples, a Hadamard matrix based OCC design may be used.

Abstract: Aspects of the disclosure relate to implied and explicit mapping of uplink (UL) resources for acknowledgment communications from a user equipment (UE). In some examples disclosed herein, implied mapping may include indexing of information elements in a downlink (DL) communication. The explicit mapping may include information elements in the DL communication configured to explicitly provide a location of an UL resource. Other aspects, embodiments, and features are also claimed and described.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive a configuration indicating one or more directions for applying directional digital pre-distortion (DPD) to mitigate interference in a direction to another UE. The UE may transmit a communication to a wireless node based at least in part on applying the directional DPD according to the configuration. Numerous other aspects are described.

Abstract: Certain aspects of the present disclosure generally relate to wireless communications, and more specifically increasing user capacity through a frame structure which supports enhanced Machine Type Communication (eMTC) UL multi-user multiplexing. For example, a User Equipment (UE) identifies at least one narrowband region within a wider system bandwidth. The UE receives signaling, from a base station, indicating a sub-region of the narrowband region assigned to the UE for transmitting symbols of a physical uplink channel that are multiplexed with symbols transmitted by one or more other UEs in the narrowband region. The UE transmits the physical uplink channel in the assigned sub-region. Similar techniques are also provided that may be applied to DL multi-user multiplexing.

Abstract: Systems, methods, and devices for wireless communication that support mechanisms signaling non-linearities to a victim user equipment (UE) for interference cancellation in a wireless communication system. A victim UE may experience interference from an uplink transmission by an aggressor UE to a base station. The victim UE may obtain a power amplifier model associated with the aggressor UE. The power amplifier may include a non-linearity model of a power amplifier of the aggressor UE causing the interference on the victim UE. The power amplifier model obtained by the victim UE may be dependent on various parameters, such as a transmit power used by the aggressor UE to transmit the uplink transmission causing the interference. Based on the aggressor UE transmit power, the victim UE may select parameters for power amplifier model and may estimate the interference caused by the uplink transmission for interference cancellation.

Abstract: Disclosed are techniques for communication. In an aspect, a first UE determines information (e.g., from an external device, or via the first UE’s own energy sensing) associated with scheduled uplink transmissions on a set of symbols by a second UE. The first UE performs measurements on at least some of the scheduled uplink transmissions during a first subset of the set of symbols where no DL signals are received by the first UE. The first UE receives at least one DL signal during a second subset of the set of symbols, and mitigates interference associated with the at least one DL signal based on the measurements.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a first mobile station may determine at least one of a channel between the first mobile station and a second mobile station or a relative direction between the first mobile station and the second mobile station. The first mobile station may apply nulling to a communication between the first mobile station and a base station based at least in part on the at least one of the channel between the first mobile station and the second mobile station or the relative direction between the first mobile station and the second mobile station. Numerous other aspects are described.

Abstract: Methods, systems, and devices for wireless communication are described. A user equipment (UE) may identify that it is scheduled to transmit an uplink message during one or more symbols of a first transmission time interval (TTI) is scheduled to receive a downlink message during a second TTI subsequent to the first TTI. The UE may advance transmission of the uplink message in accordance with a timing advance (TA) value and a TA offset value, such that the timing advance offset value is zero. The UE may proceed to apply a transient power mitigation scheme to mitigate potential interference to reception of the downlink message during a transient power duration associated with turning off an uplink transmission chain used for transmitting the uplink message. In some examples, the transient power mitigation scheme may be applied based on the TA offset value being zero.

Abstract: A UE may be configured for half-duplex communications. An access point may configure half-duplex UEs for efficient resource utilization using two or more different half-duplex configurations that include different timing for channels in different directions. A UE may determine a half-duplex configuration for use in communicating with the access point, each slot of the half-duplex configuration including at least a PDCCH on a downlink frequency and an uplink short burst on an uplink frequency, and each slot associated with a HARQ timeline. The UE may determine a direction for a slot. The UE may transmit or receive according to the direction for the slot and the half-duplex configuration.

Abstract: Methods, systems, and devices for wireless communications are described in which a base station may identify a null space matrix that lies within a null space of an effective channel matrix for communications between the base station and a user equipment (UE). An indication of the null space matrix may be provided to the UE, and the null space matrix used to determine modifications to a precoding matrix. The base station and UE may determine a redistribution matrix that provides a reduced variance of transmission powers for a number of transmission channels, where a product of the null space matrix and the redistribution matrix may be computed and added to the precoding matrix to generate a modified precoding matrix. The modified precoding matrix may be used to generate the communications from the base station and UE with reduced power variance across channels.

Abstract: Methods, systems, and devices for wireless communications are described. In some systems, a user equipment (UE) may perform channel state information (CSI) measurements on one or more reference signal transmissions received from a base station. Based on the CSI measurements, the UE may generate a CSI report, and the UE may transmit the CSI report to the base station. In some cases, the generated CSI report may include a first portion and a second portion. The first portion may indicate whether the second portion of the CSI report includes full-band CSI feedback or partial-band CSI feedback. The second portion may provide the CSI feedback for one or more identified sub-bands. In some cases, the second portion may include a sub-band index indicating the identified sub-bands. Additionally or alternatively, the second portion may include a bitmap indicating a correspondence between multiple CSI feedback values and multiple corresponding sub-band indexes.

Abstract: Aspects of the present disclosure relate to wireless communication systems configured to provide user equipment (UE)-specific slot structures based on the individual propagation delay experienced by each UE. In some examples, the duration of uplink transmissions for a particular UE within a slot may be configured based on the propagation delay between the base station and that particular UE. For example, the duration of an uplink burst and/or an uplink traffic transmission may be configured based on the propagation delay. In addition, a downlink burst within a slot may be configured for a particular UE on the propagation delay experienced by that UE. Downlink traffic transmissions may further be configured for the cell based on the maximum propagation delay experienced by the UEs in the cell.

Abstract: Methods, systems, and devices for wireless communications are described. In some systems (e.g., non-orthogonal multiple access (NOMA) systems), a base station may serve a large number of user equipments (UEs) on the uplink. To improve detectability for these uplink transmissions (e.g., if reference signals are not available for the transmissions), the UEs may implement parallel transmissions of preambles with uplink data. A UE may split the uplink data into one or more data layers, and may select one or more preamble layers to transmit superposed with the data layers. These preambles may be sequences known to both the UE and the base station to aid in detectability. The UE may assign different signature sequences to each of these layers based on cross-correlation values (e.g., assigning sequences with higher cross-correlation values to the data layers for improved detectability), and may scramble the layers into a single shared signal for transmission.

Abstract: Methods, systems, and devices for wireless communication are described that provide for uplink channel multiplexing and waveform selection. Uplink channels to be transmitted from one or more user equipment (UEs) to a base station are multiplexed together or separately into an uplink subframe. Each UE is capable of using different waveforms to transmit different channels. Reference signals are communicated according to an RS pattern, which is symmetric across uplink and downlink channels.

Abstract: Certain aspects of the present disclosure relate to methods and apparatus for pilot design for Narrow-Band Internet of Things (NB-IoT). In certain aspects, the method generally includes determining at least one binary code sequence to use as a demodulation reference signal (DMRS) for a channel transmitted across one or more subframes using one or more tones within a resource block (RB) allocated to the UE for narrowband communication, and transmitting the channel including the DMRS using the one or more tones and the determined binary code sequence. In certain aspects, the binary code sequence may be determined based on a binary random sequence, such as pseudo noise (PN) or Gold sequence.

Abstract: Methods, systems, and devices for wireless communications are described. In some systems, a user equipment (UE) may transmit feedback to a base station indicating phase values for sub-bands in a bandwidth part (BWP). The base station may use the phase feedback to perform precoding on a set of beams. To support a reduced payload overhead for the feedback, the UE may implement differential phase feedback. For example, the UE may divide the BWP into a number of sub-band groups and may generate, for each sub-band group of each beam, a first set of bits indicating an absolute phase value for a first sub-band of the sub-band group. The UE may additionally generate a second set of bits indicating differential phase values for the other sub-bands of each sub-band group. The UE may report the first and second sets of bits for the beams to the base station for precoding.

Abstract: Methods, systems, and devices for wireless communications are described. A user equipment (UE) may receive signaling that configures a downlink bandwidth for a broadcast channel transmission (e.g., a physical downlink control channel transmission). The UE may determine a bandwidth of the capability is less than the downlink bandwidth, and monitor search space occasions in a period to receive samples of the broadcast channel. The period and the search space occasions may be associated with a control resource set and a search space set. The UE may receive the samples in non-overlapping subbands of the bandwidth according to the bandwidth capability, and detect the broadcast channel based on the samples. The UE may additionally monitor repeated transmission occasions in the period based on detecting the broadcast channel to detect a second broadcast channel (e.g., a physical downlink shared channel).

Abstract: Methods, systems, and devices for wireless communications are described for controlling multiplexing of a reference signal on an uplink shared channel (UL-SCH). In an implementation, a user equipment (UE) may time division multiplex (TDM) a demodulation reference signal (DMRS) with other signaling across symbol periods of one or more allocated resource blocks. The UE may map the DMRS to resource elements of one or more symbol periods within the allocated resource blocks. The UE may then map uplink control information (UCI) to one or more symbol periods different than the symbol periods of the DMRS mapping. In some cases, the DMRS, UCI, or both may be frequency interleaved with UL-SCH data for the allocated resource blocks. The UE may generate and transmit an uplink waveform for transmission within the allocated resources of the uplink shared channel.