Abstract: This disclosure provides methods, devices and systems for channel sounding for wireless communications. Some implementations more specifically relate to scheduling sounding reference signal (SRS) resource sets for wireless devices having more than 4 receive (RX) antenna ports. In some implementations, a base station may determine an antenna switching capability of a user equipment (UE). The antenna switching capability indicates a number of RX antenna ports of the UE. The base station schedules a number of SRS resource sets for the UE based at least in part on the number of RX antenna ports in excess of four. For example, the number of RX antenna ports may be equal to 8. As another example, the number of RX antenna ports may be equal to 6. The base station further receives, from the UE, uplink transmissions of one or more SRS resources for each of the scheduled SRS resource sets.

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: 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: Certain aspects of the present disclosure provide techniques for fast adaptation of transmission properties of sounding reference signal (SRS) resource sets. A method that may be performed by a user equipment (UE) includes receiving sounding reference signal (SRS) configuration information, configuring the UE with one or more SRS resource sets, wherein each of the one or more SRS resource sets comprises one or more SRS resources; receiving signaling comprising a field indicating which of the one or more SRS resources in the one or more SRS resource sets are active and which of the one or more SRS resources in the one or more SRS resources sets are inactive; and transmitting one or more SRSs using only the one or more SRS resources that are active.

Abstract: Certain aspects of the present disclosure relate to methods and apparatus for a UE to flexibly indicate a preferred precoding resource block group (PRG) size to a base station (e.g., an eNB).

Abstract: Disclosed are techniques for computing and reporting a relevance metric for a positioning beacon beam. In an aspect, a first node receives, from a second node, a plurality of beams, determines a relevance metric for each of one or more beams of interest from the plurality of beams, wherein the relevance metric for each beam of the one or more beams of interest is based on a time of arrival at the first node of the beam and a signal strength of the beam, and sends, to the second node, a report identifying each of the one or more beams of interest and including the relevance metric for each of the one or more beams of interest.

Abstract: Aspects of the present disclosure disclose techniques for the indication of the allocation of the downlink (DL) demodulation reference signal (DM-RS) ports for the data channel in NR communications. In some examples, the channel state information (CSI) reference signal (CSI-RS) may be associated with a corresponding DM-RS for a DL data channel. The transmitting device, in some examples, may further transmit a notification that provides resource allocations (e.g., port allocations) that minimize the redundant information that is required to be transmitted from the base station to the user equipment (UE) when the DM-RS port allocation is the same as the CSI-RS port allocation received by the UE in an earlier time slot.

Abstract: Aspects of the present disclosure provide methods and apparatuses for sounding reference signal (SRS) enhancements. An exemplary method performed by a user equipment generally includes receiving information indicating a symbol, in a sub-frame of a radio frame used to communicate in the wireless network, for transmission of sounding reference signals (SRSs), wherein a location of the symbol in the sub-frame is based, at least in part, on a location of the UE and transmitting a SRS in the symbol based on the received information.

Abstract: Disclosed are techniques for receive beam selection for measuring a reference radio frequency (RF) signal. In an aspect, a first node determines a type of measurement to be performed on the reference RF signal, selects a receive beam based on the type of measurement to be performed on the reference RF signal, generates the selected receive beam, receives, from a second node, using the generated receive beam, the reference RF signal transmitted on a wireless channel, and performs one or more measurements on the received reference RF signal according to the type of the measurement to be performed.

Abstract: Disclosed are techniques for receive beam selection for measuring a reference radio frequency (RF) signal. In an aspect, a first node determines a type of measurement to be performed on the reference RF signal, selects a receive beam based on the type of measurement to be performed on the reference RF signal, generates the selected receive beam, receives, from a second node, using the generated receive beam, the reference RF signal transmitted on a wireless channel, and performs one or more measurements on the received reference RF signal according to the type of the measurement to be performed.

Abstract: Various aspects are described for an enhanced power headroom report (PHR) for feeding back beamformed sounding reference signal (SRS) power scaling. Beamformed SRS along directions where a user equipment (UE) can best nullify interference/maximize downlink (DL) signal to interference plus noise ratio (SINR) would be very helpful for DL beamforming. SRS beamforming requires additional support, if rank related decisions are being made at eNB. For example, power normalization factors need to be sent or reported on the uplink (UL) to eNB. This disclosure provides examples of how the PHR on the uplink can be used to do such reporting. There are two types of PHR being proposed, one nominal for the UL-oriented SRS, like LTE-style PHR, and one for the DL-oriented SRS where the UE also reports or indicates the power normalization factors of each SRS port.

Abstract: Aspects of the present disclosure describe receiving, from an access point, an indication of at least one of a beamforming method for beamforming a RS or a normalization method for normalizing power for beamforming the RS. A channel covariance matrix corresponding to interference over a plurality of antenna ports can be generated, as well as a RS beamforming matrix based at least in part on modifying the channel covariance matrix and on the normalization method. The RS can be generated based on the RS beamforming matrix and the beamforming method. The RS can be transmitted to the access point based on the RS beamforming matrix.

Abstract: Aspects of the present disclosure describe receiving, from an access point, an indication of at least one of a beamforming method for beamforming a RS or a normalization method for normalizing power for beamforming the RS. A channel covariance matrix corresponding to interference over a plurality of antenna ports can be generated, as well as a RS beamforming matrix based at least in part on at least one of modifying the channel covariance matrix or on the normalization method. The RS can be generated based on the RS beamforming matrix and the beamforming method. The RS can be transmitted to the access point based on the RS beamforming matrix.

Abstract: Certain aspects of the present disclosure relate to methods and apparatus for a UE to flexibly indicate a preferred precoding resource block group (PRG) size to a base station (e.g., an eNB).

Abstract: Aspects of the present disclosure relate to wireless communications and, more particularly, to reference signals (RS) and link adaptation for massive multiple-input multiple-output (MIMO). In one aspect, a method is provided which may be performed by a wireless device such as a base station (BS). The method generally includes receiving sounding reference signals (SRS) and at least one of: feedback regarding interference or a whitening matrix from one or more user equipments (UEs), determining beamforming parameters for transmissions to a group of one or more UEs based, at least in part, on the SRS and at least one of: the feedback regarding interference or the whitening matrix, and transmitting channel state information reference signals (CSI-RS) to UEs in the group using the determined beamforming parameters.

Abstract: In an embodiment, a network entity (e.g., a base station, a location server, etc.) transmits, to a user equipment (UE), at least one base station almanac (BSA) message that indicates (i) a set of transmission point locations associated with at least one base station, the set of transmission point locations including at least one transmission point location of a base station that is based upon a plurality of different transmission point locations associated with the base station, and (ii) a mapping of each of a plurality of beams to the at least one transmission point location. The UE receives the transmitted at least one BSA message.

Abstract: Disclosed are techniques for computing and reporting a relevance metric for a positioning beacon beam. In an aspect, a first node receives, from a second node, a plurality of beams, determines a relevance metric for each of one or more beams of interest from the plurality of beams, wherein the relevance metric for each beam of the one or more beams of interest is based on a time of arrival at the first node of the beam and a signal strength of the beam, and sends, to the second node, a report identifying each of the one or more beams of interest and including the relevance metric for each of the one or more beams of interest.

Abstract: Disclosed are techniques for receive beam selection for measuring a reference radio frequency (RF) signal. In an aspect, a first node determines a type of measurement to be performed on the reference RF signal, selects a receive beam based on the type of measurement to be performed on the reference RF signal, generates the selected receive beam, receives, from a second node, using the generated receive beam, the reference RF signal transmitted on a wireless channel, and performs one or more measurements on the received reference RF signal according to the type of the measurement to be performed.

Abstract: Systems and techniques are disclosed to enhance the efficiency of available bandwidth between UEs and base stations. A UE transmits a sounding reference signal (SRS) to the base station. The base station characterizes the uplink channel based on the SRS received and, using reciprocity, applies the channel characterization for the downlink channel. As part of applying the channel information, the base station forms the beam to the UE based on the uplink channel information obtained from the SRS. The UE may include an array of antennas, each UE transmitting a different SRS that the base station receives and uses to characterize the downlink. Multiple UEs (or a single UE with multiple antennas) transmit SRS at the same time and frequency allocation (non-orthogonal), but with each sending its own unique SRS. Further, multiple UEs (or a single UE with multiple antennas) may send their SRS at unique time/frequency allocations (orthogonal).

Abstract: Aspects of the present disclosure provide methods and apparatuses that can utilize different subframe structures to estimate a channel during wireless communication in different scenarios. When a scheduling entity determines that a scheduled entity is near or at a cell edge, the scheduled entity may use a special subframe to estimate the channel utilizing more resources of the subframe, for example data signals. The special subframe can facilitate channel estimation by using a less complex (or lower rank) modulation and coding scheme (MCS) for the data symbols than a normal subframe for other scheduled entities not located near the cell edge.