Adaptive sounding reference signal port configuration

Abstract

Various aspects of the disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) can receive a sounding reference signal (SRS) configuration that indicates a maximum number of SRS ports and whether the UE is permitted to determine an actual number of SRS ports to use for SRS transmissions that is different from the maximum number of SRS ports. The UE can determine the actual number of SRS ports to use for SRS transmissions based at least in part on the SRS configuration. The UE can transmit one or more SRSs using the actual number of SRS ports. Numerous other aspects are provided.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This Patent Application claims priority to Patent Cooperation Treaty (PCT) Patent Application No. PCT / CN2019 / 090887, titled “ADAPTIVE SOUNDING REFERENCE SIGNAL PORT CONFIGURATION” and filed on June 12, 2019, and which is assigned to the assignee hereof. The disclosure of the priority application is hereby TECHNICAL FIELD

[0003] Aspects of the present disclosure generally relate to wireless communication and techniques and apparatuses for adaptive sounding reference signal port configuration. BACKGROUND

[0004] Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems can employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, and / or the like). Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, time division synchronous code division multiple access (TD-SCDMA) systems, and long term evolution (LTE). LTE / LTE-Advanced is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by the Third Generation Partnership Project (3 GPP).

[0005] A wireless communication network can include a number of base stations (BSs) that can support communication for a number of user equipment (UEs). A user equipment (UE) can communicate with a base station (BS) via the downlink and uplink. The downlink (or forward link) refers to the communication from the BS to the UE, and the uplink (or reverse link) refers to the communication from the UE to the BS. As will be described in more detail

[0006] The above multiple access technologies have been adopted in various telecommunication standards to provide common protocols facilitating communication among wireless devices from different technologies. New Radio (NR), which can also be referred to as 5G, is a set of enhancements to the LTE mobile standard promulgated by the Third Generation Partnership Project (3GPP). NR is designed to better support mobile broadband Internet access by improving spectral efficiency, lowering costs, improving services, making use of new spectrum, and better integrating with other open standards using orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) (CP-OFDM) on the downlink (DL), using CP- OFDM and / or SC-FDM (e.g., also known as discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-s-OFDM)) on the uplink (UL), as well as supporting beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation. However, as the demand for mobile broadband access continues to increase, there exists a need for further improvements in LTE and NR technologies. Preferably, these improvements should be applicable to other multiple access technologies and the telecommunication standards that employ these technologies. SUMMARY

[0007] In some aspects, a method of wireless communication performed by a user equipment (UE) can include receiving a sounding reference signal (SRS) configuration indicating a maximum number of SRS ports and whether the UE is permitted to determine an actual number of SRS ports to use for SRS transmissions that is different from the maximum number of SRS ports, determining the actual number of SRS ports to use for SRS transmissions based at least in part on the SRS configuration, and transmitting one or more SRSs using the actual number of SRS ports.

[0008] In some aspects, a method of wireless communication performed by a base station can include transmitting, to a UE, an SRS configuration indicating a maximum number of SRS ports allowed for the UE and that the UE is permitted to determine an actual number of SRS ports to use for SRS transmissions that is different from the maximum number of SRS ports, determining whether one or more SRS symbols overlap with one or more physical uplink control channel (PUCCH) symbols, and transmitting, to the UE, an indication of whether to transmit a rank indicator (RI) report based at least in part on whether the one or more SRS symbols overlap with the one or more PUCCH symbols.

[0009] In some aspects, a UE for wireless communication can include a memory and one or more processors operatively coupled to the memory. The memory and the one or more processors can be configured to receive a SRS configuration indicating a maximum number of SRS ports and whether the UE is permitted to determine an actual number of SRS ports to use for SRS transmissions that is different from the maximum number of SRS ports, determine the actual number of SRS ports to use for SRS transmissions based at least in part on the SRS configuration, and transmit one or more SRSs using the actual number of SRS ports.

[0010] In some aspects, a base station for wireless communication can include a memory and one or more processors operatively coupled to the memory. The memory and the one or more processors can be configured to transmit, to a UE, a SRS configuration indicating a maximum number of SRS ports allowed for the UE and that the UE is permitted to determine an actual number of SRS ports to use for SRS transmissions that is different from the maximum number of SRS ports, determine whether one or more SRS symbols overlap with one or more PUCCH symbols, and transmit, to the UE, an indication of whether to transmit an RI report based at least in part on whether the one or more SRS symbols overlap with the one or more PUCCH symbols.

[0011] In some aspects, a non-transitory computer-readable medium can store one or more instructions for wireless communication. The one or more instructions, when executed by one or more processors of a UE, can cause the one or more processors to receive a SRS configuration indicating a maximum number of SRS ports and whether the UE is permitted to determine an actual number of SRS ports to use for SRS transmissions that is different from the maximum number of SRS ports, determine the actual number of SRS ports to use for SRS transmissions based at least in part on the SRS configuration, and transmit one or more SRSs using the actual number of SRS ports.

[0012] In some aspects, a non-transitory computer-readable medium can store one or more instructions for wireless communication. The one or more instructions, when executed by one or more processors of a base station, can cause the one or more processors to transmit, to a UE, a SRS configuration indicating a maximum number of SRS ports allowed for the UE and that the UE is permitted to determine an actual number of SRS ports to use for SRS transmissions that is different from the maximum number of SRS ports, determine whether one or more SRS symbols overlap with one or more PUCCH symbols, and transmit, to the UE, an indication of whether to transmit an RI report based at least in part on whether the one or more SRS symbols overlap with the one or more PUCCH symbols.

[0013] In some aspects, an apparatus for wireless communication can include means for receiving a SRS configuration indicating a maximum number of SRS ports and whether the apparatus is permitted to determine an actual number of SRS ports to use for SRS transmissions that is different from the maximum number of SRS ports; means for determining the actual number of SRS ports to use for SRS transmissions based at least in part on the SRS configuration; and means for transmitting one or more SRSs using the actual number of SRS ports.

[0014] In some aspects, an apparatus for wireless communication can include means for transmitting, to a UE, a SRS configuration indicating a maximum number of SRS ports allowed for the UE and that the UE is permitted to determine an actual number of SRS ports to use for SRS transmissions that is different from the maximum number of SRS ports; means for determining whether one or more SRS symbols overlap with one or more PUCCH symbols; and means for transmitting, to the UE, an indication of whether to transmit a RI report based at least in part on whether the one or more SRS symbols overlap with the one or more PUCCH symbols.

[0015] Aspects of the disclosure relate to a method, apparatus, system, computer program product, non-transitory computer-readable medium, user equipment, base station, wireless communication device, and / or processing system substantially as described herein with reference to and as illustrated by the accompanying drawings and specification.

[0016] The foregoing has outlined rather broadly the features and technical advantages of examples according to the disclosure in order that the detailed description that follows can be better understood. Additional features and advantages will be described below. The disclosed concepts and specific examples can be readily utilized as bases for modifying or designing other structures for carrying out the same purposes of the present disclosure. Such equivalent constructions do not depart from the scope of the appended claims. The features, nature, and organization of the concepts disclosed herein, and the related advantages will be better understood from the following description considered with the attached drawings. Each of the figures is provided to illustrate and describe aspects of the disclosure, and is not intended to limit the scope of the claims. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order that the above-recited features and advantages of the present disclosure can be understood in detail, a more particular description will be rendered by reference to various aspects, some of which are illustrated in the appended drawings. It is appreciated that the appended drawings are intended to be illustrative only and are not limiting in any way. It is also appreciated that the features, relationships and combinations of features that are disclosed are indicative of some of the many embodiments of the disclosure. Accordingly, the appended drawings are incorporated herein and made part of the specification, illustrating aspects of the present disclosure.

[0018] Figure 1 is a block diagram conceptually illustrating an example of a wireless communication network, in accordance with aspects of the present disclosure.

[0019] Figure 2 is a block diagram conceptually illustrating an example of a base station in communication with a UE in a wireless communication network, in accordance with aspects of the present disclosure.

[0020] Figure 3 is a diagram illustrating an example of a channel state feedback mechanism that supports hybrid channel state feedback, in accordance with aspects of the present disclosure.

[0021] Figures 4-8 is a diagram illustrating an example of adaptive sounding reference signal port configuration, in accordance with aspects of the present disclosure.

[0022] Figure 9 and Figure 10 is a diagram illustrating an example process related to adaptive sounding reference signal port configuration, in accordance with aspects of the present disclosure. DETAILED DESCRIPTION

[0023] Various aspects of the disclosure are described in further detail below. The aspects of the disclosure may, however, be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Based on the teachings herein one skilled in the art should appreciate that the scope of the disclosure is intended to cover any aspect of the disclosure disclosed herein, whether implemented independently of, or combined with, any other aspect of the disclosure. For example, an apparatus can be implemented or a method can be practiced using any number of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover an apparatus or method practiced using, for example, a different structure, functionality, or structure and functionality in addition to or other than the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein can be embodied by one or more elements of a claim.

[0024] Several aspects of telecommunication systems will now be presented with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as "elements"). These elements can be implemented using hardware, software, or combinations thereof. Whether such elements are implemented as hardware or software depends on the particular application and design constraints imposed on the overall system.

[0025] It should be noted that while aspects can be described herein using terminology commonly associated with 3G and / or 4G wireless technologies, aspects of the present disclosure can be applied in other generation-based communication systems, such as 5G and later, including NR technologies.

[0026] Figure 1 is a schematic diagram illustrating a wireless network 100 in which aspects of the present disclosure can be practiced. The wireless network 100 can be an LTE network or some other wireless network, such as a 5G or NR network. The wireless network 100 can include a number of BSs 110 (shown as BS 110a, BS 110b, BS 110c, and BS 1 lOd) and other network entities. A BS is an entity that communicates with user equipment (UEs) and can also be referred to as a base station, a NR BS, a NodeB, a gNB, a 5G nodeB (NB), an access point, a transmit receive point (TRP), and / or the like. Each BS can provide communication coverage for a particular geographic area. In 3GPP, the term “cell” can refer to a coverage area of a BS and / or a BS subsystem serving the coverage area, depending on the context in which the term is used.

[0027] BSs can provide communication coverage for a macro cell, a pico cell, a femto cell, and / or another type of cell. A macro cell can cover a relatively large geographic area (e.g., 5 kilometers in radius) and can allow unrestricted access by UEs with service subscription. A pico cell can cover a relatively small geographic area and can allow restricted access by UEs with service subscription. A femto cell can cover a relatively small geographic area (e.g., a home) and can allow restricted access by UEs with service subscription, such as UEs in a closed subscriber group (CSG). A BS for a macro cell can be referred to as a macro BS. A BS for a pico cell can be referred to as a pico BS. A BS for a femto cell can be referred to as a femto BS or a home BS. In the present disclosure, a BS can be referred to simply as a “BS” and / or the like, and its various instances can be referred to as the BS 110 and / or the like. Figure 1 In the example shown, the BS 110a can be a macro BS for the macro cell 102a, the BS 110b can be a pico BS for the pico cell 102b, and the BS 110c can be a femto BS for the femto cell 102c. A BS can support one or multiple (e.g., three) cells. In this document, the terms “eNB,” “base station,” “NR BS,” “gNB,” “TRP,” “AP,” “node B,” “5G NR,” and “cell” can be used interchangeably.

[0028] In some aspects, a cell can not necessarily be fixed in nature and can move with a mobile BS. In some aspects, the geographic area of a cell can move with the location of the mobile BS. In some aspects, BSs can be interconnected to one another and / or to one or more other BSs or network nodes in wireless network 100 through various types of backhaul interfaces such as a direct physical connection, a virtual network, and / or the like using any suitable transport network.

[0029] Wireless network 100 can also include relay stations. A relay station is an entity that can receive a transmission of data from an upstream station (e.g., a BS or a UE) and send a transmission of the data to a downstream station (e.g., a UE or a BS). A relay station can also be a UE that can relay transmissions for other UEs. In Figure 1 In the example shown, relay station 1 lOd can communicate with macro BS 110a and a UE 120d in order to facilitate communications between BS 110a and UE 120d. A relay station can also be referred to as a relay BS, a relay base station, a relay, and / or the like.

[0030] Wireless network 100 can be a heterogeneous network that includes BSs of different types, e.g., macro BSs, pico BSs, femto BSs, relay BSs, and / or the like. These different types of BSs can have different transmit power levels, different coverage areas, and different impacts on interference. For example, macro BSs can have a high transmit power level (e.g., 5 to 40 Watts), whereas pico BSs, femto BSs, and relay BSs can have lower transmit power levels (e.g., 0.1 to 2 Watts).

[0031] A network controller 130 can couple to a set of BSs and can provide coordination and control for these BSs. Network controller 130 can communicate with the BSs via a backhaul. The BSs can also communicate with one another, e.g., directly or indirectly via a wireless or wireline backhaul.

[0032] The UEs 120 (e.g., 120a, 120b, 120c) can be dispersed throughout the wireless network 100, and each UE can be stationary or mobile. A UE can also be referred to as an access terminal, a terminal, a mobile station, a subscriber unit, a station, and / or the like. A UE can be a cellular phone (e.g., a smart phone), a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet, a camera, a gaming device, a netbook, a smartbook, an ultrabook, a medical device or equipment, biometric sensors / devices, wearable devices (smart watches, smart clothing, smart glasses, smart wrist bands, smart jewelry (e.g., smart ring, smart bracelet)), an entertainment device (e.g., a music or video device, or a satellite radio), a vehicular component or sensor, a smart meter / sensor, industrial manufacturing equipment, a global positioning system device, or any other suitable device that is configured to communicate via a wireless or wired medium.

[0033] Some UEs can be considered machine-type communication (MTC) or evolved or enhanced machine-type communication (eMTC) UEs. MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, location tags, and / or the like, that can communicate with a base station, another device (e.g., remote device), or some other entity. A wireless node can provide, for example, connectivity for or to a network (e.g., a wide area network such as Internet or a cellular network) via a wired or wireless communication link. Some UEs can be considered Intemet-of-Things (IoT) devices, and / or can be implemented as NB-IoT (narrowband

[0034] In general, any number of wireless networks can be deployed in a given geographic area. Each wireless network can support a particular RAT and can operate on one or more frequencies. A RAT can also be referred to as a radio technology, an air interface, and / or the like. Frequencies can also be referred to as carriers, frequency channels, and / or the like. Each frequency can support a single RAT in a given geographic area in order to avoid interference between wireless networks of different RATs. In some cases, NR or 5G RAT networks can be deployed.

[0035] In some aspects, two or more UEs 120 (e.g., shown as UE 120a and UE 120e) can communicate directly using one or more sidelink channels (e.g., without using base station 110 as an intermediary for their communications). For example, UE 120 can perform scheduling operations, resource selection operations, and / or other operations described elsewhere herein as being performed by base station 110. FIG. 2 shows a block diagram of a design 200 of base station 110 and UE 120, which can be one of the base stations and one of the UEs in FIG. 1. Base station 110 can be equipped with T antennas, and UE 120 can be equipped with R antennas, where in general T > 1 and R > 1.

[0036] As described above, Figure 1 are provided by way of example. Other examples can differ Figure 1 from those described.

[0037] Figure 2 FIG. 2 shows a block diagram of a design 200 of base station 110 and UE 120, which can be one of the base stations and one of the UEs in FIG. 1. Base station 110 can be equipped with T antennas, and UE 120 can be equipped with R antennas, where in general T > 1 and R > 1. Figure 1

[0038] ​At base station 110, a transmit processor 220 can receive data from a data source 212 for one or more UEs, select one or more modulation and coding schemes (MCS) for each UE based at least in part on channel quality indicators (CQIs) received from the UE, process (e.g., encode and modulate) the data for each UE based at least in part on the MCS(s) selected for the UE, and provide data symbols for all UEs. Transmit processor 220 can also process system information (e.g., for semi-static resource partitioning information (SRPI), etc.) and control information (e.g., CQI requests, grants, upper layer signaling, etc.) and provide overhead symbols and control symbols. Transmit processor 220 can also generate reference symbols for reference signals (e.g., a cell-specific reference signal (CRS)) and synchronization signals (e.g., a primary synchronization signal (PSS) and a secondary synchronization signal (SSS)). A transmit (TX) multiple-input multiple-output (MIMO) processor 230 can perform spatial processing (e.g., precoding) on the data symbols, the control symbols, the overhead symbols, and / or the reference symbols, if applicable, and can provide T output symbol streams to T modulators (MODs) 232a through 232t. Each modulator 232 can process a respective output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator 232 can further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. T downlink signals from modulators 232a through 232t can be transmitted via T antennas 234a through 234t, respectively. According to various aspects described in more detail below, the synchronization signals can be generated with location encoding to convey additional information.

[0039] At the UE 120, the antennas 252a through 252r can receive the downlink signals from the base station 110 and / or other base stations and can provide received signals to the demodulators (DEMODs) 254a through 254r, respectively. Each demodulator 254 can condition (e.g., filter, amplify, downconvert, and digitize) a received signal to obtain input samples. Each demodulator 254 can further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. A MIMO detector 256 can obtain received symbols from all R demodulators 254a through 254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor 258 can process (e.g., demodulate and decode) the detected symbols, provide decoded data for the UE 120 to a data sink 260, and provide decoded control information and system information to a controller / processor 280. The channel processor can determine reference signal received power (RSRP), received signal strength indicator (RSSI), reference signal received quality (RSRQ), channel quality indicator (CQI), etc. In some aspects, one or more components of UE 120 can be included in a housing.

[0040] On the uplink, at the UE 120, a transmit processor 264 can receive and process data from a data source 262 and control information (e.g., for reports including RSRP, RSSI, RSRQ, CQI, etc.) from the controller / processor 280. Transmit processor 264 can also generate reference symbols for one or more reference signals. The symbols from transmit processor 264 can be precoded by a TX MIMO processor 266 if applicable, further processed by modulators 254a through 254r (e.g., for DFT-s-OFDM, CP-OFDM, etc.), and transmitted to the base station 110. At the base station 110, the uplink signals from UE 120 and other UEs can be received by the antennas 234, processed by the demodulators 232, detected by a MIMO detector 236 if applicable, and further processed by a receive processor 238 to obtain decoded data and control information sent by UE 120. The receive processor 238 can provide the decoded data to a data sink 239 and the decoded control information to a controller / processor 240. The base station 110 can include a communication unit 244 and communicate with the network controller 130 via the communication unit 244. The network controller 130 can include a communication unit 294, a controller / processor 290, and a memory 292.

[0041] Figure 2The controller / processor 240 of the base station 110, the controller / processor 280 of the UE 120, and / or any other component may perform one or more techniques associated with adaptive sounding reference signal port configuration, as described in more detail elsewhere herein. For example, Figure 2 The controller / processor 240 of the base station 110, the controller / processor 280 of the UE 120, and / or any other component may perform or direct, for example, Figure 9 The process of 900 Figure 10 The operations of process 1000 and / or other processes as described herein may be performed. Memories 242 and 282 may store data and program codes for base station 110 and UE 120, respectively. Scheduler 246 may schedule data transmissions of UEs on the downlink and / or uplink.

[0042] In some aspects, the UE 120 may include means for receiving a sounding reference signal (SRS) configuration indicating a maximum number of SRS ports and whether the UE 120 is permitted to determine an actual number of SRS ports to use for SRS transmission, the actual number of SRS ports being different from the maximum number of SRS ports; means for determining the actual number of SRS ports to use for SRS transmission based at least in part on the SRS configuration; means for transmitting one or more SRSs using the actual number of SRS ports, and the like. In some aspects, such means may include in conjunction with Figure 2 One or more components of UE 120 are described.

[0043] In some aspects, the base station 110 may include means for sending an SRS configuration to the UE, the SRS configuration indicating a maximum number of SRS ports allowed for the UE and an actual number of SRS ports that the UE is permitted to determine to use for SRS transmission, the actual number of SRS ports being different from the maximum number of SRS ports; means for determining whether one or more SRS symbols overlap with one or more physical uplink control channel (PUCCH) symbols; and means for sending an indication to the UE of whether to send a rank indicator (RI) report based at least in part on whether one or more SRS symbols overlap with one or more PUCCH symbols, among other things. In some aspects, such means may include, in conjunction with Figure 2 One or more components of base station 110 are described.

[0044] As mentioned above, Figure 2 Provided as an example. Other examples can be found in the Figure 2 Different than described.

[0045] Figure 3is a diagram illustrating an example 300 of a channel state feedback mechanism that supports hybrid channel state feedback, in accordance with aspects of the present disclosure.

[0046] As shown by reference number 305, the base station can transmit a set of downlink reference signals in a downlink time slot, which is shown as a set of channel state information reference signals (CSI-RSs) 310. The UE can receive and measure the set of CSI-RSs 310 to determine a transmission rank and / or a channel quality. For example, the UE can perform channel estimation (e.g., H*B) across precoded CSI-RS ports to determine an RI value and / or a channel quality indicator (CQI) value. For channel estimation, H indicates a downlink channel, and B indicates a precoder used for the downlink CSI-RSs. Thus, H*B can represent a channel estimate measured from the precoded CSI-RS ports.

[0047] The UE can transmit an indication of the RI value and / or the CQI value on an uplink control channel 315, which is shown as a PUCCH. In some cases, the UE can determine a singular value decomposition (SVD) of a precoded channel using the channel estimate H*B. For example, the UE can compute an eigenvector corresponding to an SVD of a matrix combination corresponding to the channel estimate H*B. In some aspects, the UE can compute an eigenvector and a precoding matrix indicator (PMI) from the channel estimate. For example, the UE can determine, based at least in part on the channel estimate, a right eigenvector D, a left eigenvector U (sometimes referred to as a spatial domain transmit filter U, a linear receiver U, and / or the like), and a PMI V. The PMI can correspond to the RI value and the CQI value determined by the UE. The UE can indicate the RI value and the CQI value in the uplink control channel 315 (e.g., the PUCCH), and can indicate the computed PMI V using one or more sounding reference signals (SRSs) 320.

[0048] In some aspects, the UE can transmit the one or more SRSs 320, which indicate a precoding matrix associated with the determined RI and CQI. For example, the UE can precode the SRSs using the left eigenvector U (e.g., a linear receiver, a spatial domain transmit filter, and / or the like). The base station can use the left eigenvector U to derive and / or estimate a precoder V (e.g., the PMI V) corresponding to the RI value and / or the CQI value. As shown by reference number 325, the base station can transmit a data communication, such as a physical downlink shared channel (PDSCH) communication, to the UE using the estimated precoder (e.g., a beam).

[0049] Thus, when a UE reports hybrid analog channel state feedback (CSF) (sometimes referred to as analog CSF), the UE reports an RI value and / or a CQI value in a PUCCH communication, and the UE precodes SRS using a precoder matrix U (e.g., left eigenvectors, spatial domain transmit filter, linear receiver, etc.). Because the precoder matrix U is determined from a set of downlink CSI-RS received from the base station, the UE should be configured with an association between a set of SRS resources to be used to transmit SRS precoded using the precoder matrix U (e.g., SRS for reporting analog CSF) and a set of downlink CSI-RS to be used to determine the precoder matrix U. With this configuration, the UE can determine the precoder matrix U from the associated set of downlink CSI-RS and can precoded SRS transmitted on the set of SRS resources using the precoder matrix U, and the base station can appropriately derive a PMI from the precoded SRS.

[0050] In some cases, a base station can configure a UE with a number of SRS ports that the UE is to use to transmit SRS. The UE can be required to transmit SRS on all of the configured SRS ports (e.g., one SRS per configured SRS port). For example, if the base station configures the UE with two SRS ports, the UE can be required to transmit a first SRS on a first SRS port and a second SRS on a second SRS port. Similarly, if the base station configures the UE with four SRS ports, the UE can be required to transmit a first SRS on a first SRS port, a second SRS on a second SRS port, a third SRS on a third SRS port, and a fourth SRS on a fourth SRS port. In this case, the actual number of SRS ports that the UE is required to use to transmit SRS is the same as the configured number of SRS ports.

[0051] However, in certain cases, the UE can not need to transmit SRS on every configured SRS port. For example, when SRS is used for analog CSF (e.g., when one or more SRS are precoded using a precoder U), as described above, the UE can only need to report a subset of the columns of the precoder U (e.g., one column per SRS), which can be less than the number of configured ports. For example, the UE can be configured by the base station to use four SRS ports (e.g., for uplink channel measurement), but can only need to use two SRS ports for analog CSF (e.g., for an RI value of 2) to permit the base station to derive a PMI value. There can be other cases where SRS is not used to probe the uplink channel, but for other purposes that do not require the UE to transmit SRS on every configured SRS port.

[0052] Some of the techniques and apparatuses described herein permit a UE to transmit SRS using fewer than all configured SRS ports. In this way, signaling overhead can be reduced. In some cases, SRS ports that are not used for SRS transmission can be repurposed for other transmissions (e.g., data transmissions, control transmissions, etc.), thereby increasing throughput, reducing latency, and improving network performance. Moreover, because a base station can be able to derive an RI value from the number of SRS ports that occur for an SRS transmission, some of the techniques and apparatuses described herein can permit a UE to forego transmission of an RI value, thereby conserving network resources and resources of the UE (e.g., processing resources, memory resources, etc.) that would otherwise be used to generate and / or transmit the RI value.

[0053] As described above, Figure 3 are provided by way of example. Other examples can differ Figure 3 from the described examples.

[0054] Figure 4 FIG. 4 is a diagram illustrating an example 400 of adaptive sounding reference signal port configuration, in accordance with aspects of the present disclosure. As shown, Figure 4 Base stations 110 and UEs 120 can communicate with one another.

[0055] As shown by reference number 405, base station 110 can transmit an SRS configuration, and UE 120 can receive the SRS configuration. In some aspects, the SRS configuration can be transmitted in a radio resource control (RRC) message, such as an RRC configuration message, an RRC reconfiguration message, and / or the like. For example, the SRS configuration can be a higher layer parameter (e.g., SRS-Config) included in an RRC message.

[0056] As shown, the SRS configuration can indicate a maximum number of SRS ports for UE 120, which can be referred to using the variable M. The maximum number of SRS ports can indicate a maximum number of SRS ports that UE 120 can use to transmit SRS for each SRS resource (e.g., each time domain resource, such as a symbol). The maximum number of SRS ports indicated in the SRS configuration can be, for example, one SRS port, two SRS ports, four SRS ports, and / or the like. Additionally, or alternatively, the SRS configuration can indicate whether UE 120 is permitted to determine an actual number of SRS ports to use for SRS transmissions (e.g., SRS transmissions of one or more SRSs) that is different from the maximum number of SRS ports. In some aspects, the indication can include a single bit, where a first value of the bit (e.g., 1) indicates that UE 120 is permitted to determine an actual number of SRS ports that is different from the maximum number of SRS ports, and a second value of the bit (e.g., 0) indicates that UE 120 is not permitted to determine an actual number of SRS ports that is different from the maximum number of SRS ports.

[0057] The actual number of SRS ports can refer to the number of SRS ports actually used by the UE 120 to transmit SRS, and can be denoted with the variable T. In some aspects, the capability to determine (and / or use) an actual number of SRS ports that is different than a maximum number of SRS ports can be referred to as adaptive SRS port configuration or dynamic SRS port configuration. In some aspects, for an indicated SRS usage, such as analog CSF usage (e.g., transmission of SRSs that are precoded using a spatial domain transmit filter U, as described above in connection with Figure 3

[0058] As shown by reference number 410, the UE 120 can determine, based at least in part on the SRS configuration, an actual number of SRS ports to use for SRS transmissions. As shown, if the SRS configuration indicates that the UE 120 is not permitted to determine an actual number of SRS ports that is different than a maximum number of SRS ports, the UE 120 can determine an actual number of SRS ports for a set of SRS resources that is equal to a configured number of SRS ports for the set of SRS resources (e.g., indicated in the SRS configuration). For example, the SRS configuration can indicate a number of SRS ports to use for a set of SRS resources (e.g., 1, 2, 4, and / or the like). In some aspects, a SRS port number parameter (e.g., nrofSRS-Ports) can be used to indicate a number of SRS ports for a set of SRS resources. If the UE 120 is not permitted to determine an actual number of SRS ports that is different than a maximum number of SRS ports, the UE 120 can use the number of SRS ports indicated for the set of SRS resources to transmit SRS for the set of SRS resources.

[0059] As further shown, if the SRS configuration indicates that the UE 120 is permitted to determine an actual number of SRS ports that is different than a maximum number of SRS ports, the UE 120 can determine the actual number of SRS ports based at least in part on the maximum number of SRS ports (e.g., indicated in the SRS configuration) and a determined RI value of the UE 120. The UE 120 can determine the RI value based at least in part on measuring one or more downlink CSI-RSs, as described above in connection with Figure 3 ​SRS configuration can indicate an association between one or more downlink CSI-RS and a SRS resource set for which an actual number of SRS ports is being determined. The UE 120 can measure the indicated downlink CSI-RS to determine an RI value. As shown, in some aspects, such as when one or more SRS transmissions are muted, the UE 120 can set the actual number of SRS ports to equal the minimum of the maximum number of SRS ports and the RI value (e.g., T = min(RI, M)). Alternatively, in some aspects, such as when one or more SRS transmissions are repeated, the UE 120 can set the actual number of SRS ports to equal the maximum of the maximum number of SRS ports and the RI value (e.g., T = max(RI, M)). The actual number of SRS ports can be, for example, one SRS port, two SRS ports, three SRS ports, four SRS ports, and so forth.

[0060] As shown by reference number 415, the UE 120 can transmit one or more SRS using the actual number of SRS ports. For example, the UE 120 can transmit SRS for a SRS resource set using one or more time domain resources configured for the SRS resource set (e.g., in a SRS configuration), using one or more frequency domain resources configured for the SRS resource set (e.g., in a SRS configuration), and so forth. In some aspects, the UE 120 can transmit a single SRS per SRS port.

[0061] In some aspects, the UE 120 can transmit SRS on the SRS ports using the same transmit power for each SRS port. In this case, the UE 120 can determine the transmit power for each SRS port to use for actually transmitting SRS on by dividing the total (e.g., maximum) SRS transmit power by the actual number of SRS ports (e.g., Tx power per SRS port = total SRS Tx power / T). If the actual number of SRS ports is less than the maximum number of SRS ports, the UE 120 can mute SRS transmissions on one or more SRS ports (e.g., on M minus T ports). Additionally, or alternatively, if the actual number of SRS ports is less than the maximum number of SRS ports, the UE 120 can use one or more configured SRS resources (e.g., time domain resources, frequency domain resources, and / or the like) to transmit uplink communications other than SRS using SRS ports that are not used for SRS transmissions (e.g., SRS ports that are muted for SRS transmissions). For example, the UE 120 can transmit uplink data communications (e.g., physical uplink shared channel (PUSCH) communications), uplink control communications (e.g., PUCCH communications), uplink reference signals other than SRS (e.g., demodulation reference signals (DMRS)), and / or the like on the muted SRS ports. In some aspects, if the actual number of SRS ports is equal to the maximum number of SRS ports, the UE 120 can repeat SRS transmissions on one or more SRS ports (e.g., on M minus T ports).

[0062] In some aspects, the UE 120 can transmit, to the base station 110, a UE capability regarding a number of transmit antennas of the UE 120 and a number of receive antennas of the UE 120, sometimes referred to as an antenna switching capability, an SRS antenna switching capability, and / or the like. For example, the UE 120 can indicate this capability using a supportedSRS-TxPortSwitch parameter in a UE capability report. In some aspects, the base station 110 can use this UE capability to determine a maximum number of SRS ports to indicate in an SRS configuration and / or other SRS parameters (e.g., a number of SRS resources, time domain configurations of SRS resources, and / or the like).

[0063] In some aspects, the UE 120 can report a UE capability indicating that a number of transmit antennas of the UE 120 is equal to a number of receive antennas of the UE 120. For example, the SRS antenna switching capability can indicate that the UE 120 has one transmit antenna and one receive antenna (e.g., tlrl or IT = IR), can indicate that the UE 120 has two transmit antennas and two receive antennas (e.g., t2r2 or 2T = 2R), can indicate that the UE 120 has four transmit antennas and four receive antennas (e.g., t4r4 or 4T = 4R), and the like. If the base station 110 receives an indication of this capability, the base station 110 can configure a maximum number of SRS ports (e.g., in an SRS configuration) to be equal to the number of transmit antennas of the UE 120 and to be equal to the number of receive antennas of the UE 120 (e.g., because the number of transmit antennas is the same as the number of receive antennas). In some aspects, the base station 110 can indicate a maximum number of SRS ports (e.g., per SRS resource, such as a time domain resource) in an SRS configuration using an SRS port number parameter (e.g., nrofSRS-Ports) for the SRS resource. In some aspects, the base station 110 can configure a single SRS resource per SRS resource set. As described above, the UE 120 can determine an actual number of SRS ports to be less than or equal to the maximum number of SRS ports (e.g., as indicated by the SRS port number parameter for the SRS resource).

[0064] In some aspects, the UE 120 can report a UE capability indicating that a number of transmit antennas of the UE 120 is less than a number of receive antennas of the UE 120. For example, the SRS antenna switching capability can indicate that the UE 120 has one transmit antenna and two receive antennas (e.g., tlr2 or IT2R), can indicate that the UE 120 has two transmit antennas and four receive antennas (e.g., t2r4 or 2T4R), can indicate that the UE 120 has one transmit antenna and four receive antennas (e.g., tlr4 or IT4R), can indicate that the UE 120 can switch between one or two transmit antennas and the UE 120 has four receive antennas (e.g., tlr4-t2r4 or IT4R / 2T4R), and the like. If the base station 110 receives an indication of this capability, the base station 110 can configure (e.g., in an SRS configuration) a number of SRS resources equal to a maximum number of SRS ports in an SRS resource set. For example, the base station 110 can configure M SRS resources (e.g., M symbols for SRS transmissions) to the UE 120. In some aspects, the M SRS resources can be configured in a same slot, as described in more detail below in connection with FIG. 4. Alternatively, the M SRS resources can be configured in different slots (e.g., two slots), as described in more detail below in connection with FIG. 5. Figure 5 In some aspects, the UE 120 can report a UE capability indicating that a number of transmit antennas of the UE 120 is less than a number of receive antennas of the UE 120. For example, the SRS antenna switching capability can indicate that the UE 120 has one transmit antenna and two receive antennas (e.g., tlr2 or IT2R), can indicate that the UE 120 has two transmit antennas and four receive antennas (e.g., t2r4 or 2T4R), can indicate that the UE 120 has one transmit antenna and four receive antennas (e.g., tlr4 or IT4R), can indicate that the UE 120 can switch between one or two transmit antennas and the UE 120 has four receive antennas (e.g., tlr4-t2r4 or IT4R / 2T4R), and the like. If the base station 110 receives an indication of this capability, the base station 110 can configure (e.g., in an SRS configuration) a number of SRS resources equal to a maximum number of SRS ports in an SRS resource set. For example, the base station 110 can configure M SRS resources (e.g., M symbols for SRS transmissions) to the UE 120. In some aspects, the M SRS resources can be configured in a same slot, as described in more detail below in connection with FIG. 4. Alternatively, the M SRS resources can be configured in different slots (e.g., two slots), as described in more detail below in connection with FIG. 5. Figure 6 In some aspects, the UE 120 can report a UE capability indicating that a number of transmit antennas of the UE 120 is less than a number of receive antennas of the UE 120. For example, the SRS antenna switching capability can indicate that the UE 120 has one transmit antenna and two receive antennas (e.g., tlr2 or IT2R), can indicate that the UE 120 has two transmit antennas and four receive antennas (e.g., t2r4 or 2T4R), can indicate that the UE 120 has one transmit antenna and four receive antennas (e.g., tlr4 or IT4R), can indicate that the UE 120 can switch between one or two transmit antennas and the UE 120 has four receive antennas (e.g., tlr4-t2r4 or IT4R / 2T4R), and the like. If the base station 110 receives an indication of this capability, the base station 110 can configure (e.g., in an SRS configuration) a number of SRS resources equal to a maximum number of SRS ports in an SRS resource set. For example, the base station 110 can configure M SRS resources (e.g., M symbols for SRS transmissions) to the UE 120. In some aspects, the M SRS resources can be configured in a same slot, as described in more detail below in connection with FIG. 4. Alternatively, the M SRS resources can be configured in different slots (e.g., two slots), as described in more detail below in connection with FIG. 5.

[0065] By permitting the UE 120 to transmit SRS using fewer than all configured SRS ports, signaling overhead can be reduced, and resources (e.g., processing resources, memory resources, battery power, etc.) of the UE 120 can be conserved. Moreover, this can permit the analog CSF to be properly indicated with reduced ambiguity. In some cases, SRS ports that are not used for SRS transmission can be repurposed for other transmissions (e.g., data transmissions, control transmissions, etc.), thereby increasing throughput, reducing latency, and improving network performance.

[0066] As described above, Figure 4 are provided by way of example. Other examples can differ Figure 4 from the described examples.

[0067] Figure 5 is a diagram illustrating another example 500 of adaptive sounding reference signal port configuration, in accordance with aspects of the present disclosure.

[0068] As described above in connection with Figure 4 , in some aspects, the UE 120 can report a UE capability indicating that a number of transmit antennas of the UE 120 is less than a number of receive antennas of the UE 120. In this case, the base station 110 can configure a number of SRS resources in the SRS resource set equal to the maximum number of SRS ports. For example, the base station 110 can configure M SRS resources (e.g., M symbols for SRS transmission) to the UE 120. In some aspects, the M SRS resources can be configured in the same slot, as shown in Figure 5 .

[0069] For example, as shown by reference number 505, the base station 110 can configure the UE 120 with a maximum of four SRS ports (shown as M = 4). As shown by reference number 510, the UE 120 can determine an actual number of SRS ports equal to two (shown as T = 2), which is less than the maximum number of SRS ports, as described above in connection with Figure 4 . As shown by reference number 515, the UE 120 can transmit a first SRS using a first SRS port (shown as port 1) of the two SRS ports, and can transmit a second SRS using a second SRS port (shown as port 2) of the two SRS ports. In example 500, the UE 120 transmits the first SRS and the second SRS in the same slot (e.g., for each slot, such as slot n, slot n+1, etc.). In Figure 5In some aspects, the SRS ports used for actual transmission of the SRS are shown as Tx SRS ports. As shown, the UE 120 can transmit the SRS on the SRS ports over a set of physical resource blocks (PRBs) (e.g., frequency domain resources) that can be indicated in the SRS configuration. As shown by reference number 520, in some aspects, the UE 120 can mute SRS transmissions on M minus T SRS ports (e.g., two SRS ports in example 500, shown as muted or repeated SRS ports).

[0070] Alternatively, the UE 120 can repeat SRS transmissions on the M minus T SRS ports (e.g., two SRS ports in example 500, shown as muted or repeated SRS ports). In this case, the T = 2 SRS transmissions shown with reference number 515 can be repeated in the symbols shown with reference number 520. For example, as shown by reference number 515, the UE 120 can transmit a first SRS using a first of the two SRS ports (shown as port 1 in symbol 13) in a first symbol of a slot, can transmit a second SRS using a second of the two SRS ports (shown as port 2 in symbol 14) in a second symbol of the slot, can transmit the first SRS using the first SRS port (e.g., repeated port 1 in symbol 11) in a third symbol of the slot, and can transmit the second SRS using the second SRS port (e.g., repeated port 2 in symbol 12) in a fourth symbol of the slot.

[0071] In example 500, the base station 110 configures M SRS resources (e.g., M symbols) in the same slot (e.g., for the SRS resource set). For example, the base station 110 configures different SRS resources in different symbols of the same slot. In some aspects, each SRS resource (e.g., each SRS symbol) can correspond to a different SRS port (e.g., for a total of M SRS ports configured for one slot). In this case, the UE 120 can transmit SRS on T SRS resources of each slot (e.g., using T SRS ports, and using one SRS port for each SRS resource). This can be referred to as intra-slot SRS port selection. Alternatively, the base station 110 can configure the UE 120 for inter-slot SRS port selection, as described below in connection with Figure 6

[0072] As described above, Figure 5 are provided by way of example. Other examples can differ from what is described Figure 5 in connection with what is described.

[0073] Figure 6 ​is a diagram illustrating another example 600 of adaptive sounding reference signal port configuration, in accordance with aspects of the present disclosure.

[0074] As described above in connection with Figure 4 In some aspects, UE 120 can report a UE capability indicating that a number of transmit antennas of UE 120 is less than a number of receive antennas of UE 120. In this case, base station 110 can configure a number of SRS resources in the SRS resource set equal to the maximum number of SRS ports. For example, base station 110 can configure M SRS resources (e.g., M symbols for SRS transmission) to UE 120. In some aspects, the M SRS resources can be configured in different slots (e.g., across multiple slots), as Figure 6 shown in example 600. In example 600, M SRS resources are configured across two slots, with M / 2 SRS resources per slot. In some aspects, M SRS resources can be configured across a different number of slots, such as four slots.

[0075] For example, as shown by reference number 605, base station 110 can configure UE 120 with a maximum of four SRS ports (shown as M = 4). As shown by reference number 610, UE 120 can determine an actual number of SRS ports equal to two (shown as T = 2), which is less than the maximum number of SRS ports, as described above in connection with Figure 4 As shown by reference number 615, UE 120 can transmit a first SRS using a first SRS port (shown as port 1) of the two SRS ports, and can transmit a second SRS using a second SRS port (shown as port 2) of the two SRS ports. In example 600, UE 120 transmits the first SRS and the second SRS in different slots. For example, UE 120 transmits the first SRS in slot n, and transmits the second SRS in slot n + 1. In example 600, the first SRS and the second SRS are transmitted in the same symbol number (e.g., the last symbol) of different slots, although other SRS configurations can differ from example 600. As shown by reference number 620, in some aspects, UE 120 can mute SRS transmission on M minus T SRS ports (e.g., two SRS ports in example 600, shown as muted or repeated SRS ports).

[0076] Alternatively, UE 120 may repeat SRS transmissions on M minus T SRS ports (e.g., the two SRS ports in example 600, shown as muted or repeated SRS ports). In this case, T=2 SRS transmissions shown with reference numeral 615 may be repeated in the symbol shown with reference numeral 620. For example, as shown with reference numeral 615, UE 120 may transmit a first SRS using a first SRS port (shown as port 1 in symbol 13) of the two SRS ports in the first symbol of a time slot, may transmit a second SRS using a second SRS port (shown as port 2 in symbol 14) of the two SRS ports in the second symbol of the time slot, may transmit (e.g., repeat) the first SRS using the first SRS port (e.g., repeated port 1 in symbol 11) in the third symbol of the time slot, and may transmit (e.g., repeat) the second SRS using the second SRS port (e.g., repeated port 2 in symbol 12) in the fourth symbol of the time slot.

[0077] In example 600, base station 110 configures M SRS resources (e.g., M symbols) across different time slots (e.g., for an SRS resource set). For example, for a maximum number of two SRS ports, base station 110 may configure a first SRS resource in a first time slot, and base station 110 may configure a second SRS resource in a second time slot. As another example, for a maximum number of four SRS ports (e.g., as Figure 6 ), the base station 110 may configure the first SRS resource and the second SRS resource in the first time slot, and the base station 110 may configure the third SRS resource and the fourth SRS resource in the second time slot. In some aspects, each SRS resource (e.g., each SRS symbol) may correspond to a different SRS port (e.g., for a total of M SRS ports configured across different time slots). In this case, the UE 120 may send SRS on T SRS resources across different time slots (e.g., using T SRS ports and one SRS port for each SRS resource). For example, if the base station 110 configures M SRS resources across two time slots, with each time slot having M / 2 SRS resources, the UE 120 may send SRS on T SRS resources across the two time slots, with each time slot having T / 2 SRS resources. This may be referred to as inter-slot SRS port selection.

[0078] As mentioned above, Figure 6 Provided as an example. Other examples can be found in the Figure 6 Different than described.

[0079] Figure 7 is a diagram illustrating another example 700 of an adaptive sounding reference signal port configuration according to aspects of the present disclosure.

[0080] As described above in connection with Figure 4 some aspects, UE 120 can report a UE capability indicating that a number of transmit antennas of UE 120 is less than a number of receive antennas of UE 120. In this case, base station 110 can configure a number of SRS resources in the SRS resource set equal to the maximum number of SRS ports. For example, base station 110 can configure M SRS resources (e.g., M symbols for SRS transmission) to UE 120. In some aspects, the M SRS resources can be configured in different slots (e.g., across multiple slots), as shown in Figure 7 example 700. In example 700, M SRS resources are configured across two slots, with M / 2 SRS resources per slot. In some aspects, the M SRS resources can be configured across a different number of slots, such as four slots.

[0081] For example, as shown by reference number 705, base station 110 can configure UE 120 with a maximum of four SRS ports (shown as M = 4). As shown by reference number 710, UE 120 can determine an actual number of SRS ports equal to two (shown as T = 2), which is less than the maximum number of SRS ports, as described above in connection with Figure 4 example 700. As shown by reference number 715, UE 120 can transmit a first SRS using a first SRS port (shown as port 1) of the two SRS ports, and can transmit a second SRS using a second SRS port (shown as port 2) of the two SRS ports. In example 700, UE 120 transmits the first SRS and the second SRS in the same slot. For example, UE 120 transmits the first SRS and the second SRS in slot n. In example 700, the first SRS and the second SRS are transmitted in symbol 13 and symbol 14 of the slot. Other SRS configurations can differ from example 700, and the first SRS and the second SRS can be transmitted in symbols other than symbol 13 and symbol 14.

[0082] As shown by reference number 720, the UE 120 can repeat the SRS transmissions on the M minus T SRS ports (e.g., two SRS ports in example 700, shown as repeated SRS ports). In this case, the T = 2 SRS transmissions shown with reference number 715 in the first slot (e.g., slot n) can be repeated in a second slot (e.g., slot n+1). For example, as shown by reference number 715, the UE 120 can transmit a first SRS using a first of the two SRS ports (shown as port 1 in symbol 14 of slot n) in a first symbol of the first slot, and can transmit a second SRS using a second of the two SRS ports (shown as port 2 in symbol 13 of slot n) in a second symbol of the slot. As shown by reference number 720, the UE 120 can transmit (e.g., repeat) the first SRS using the first SRS port (e.g., repeated port 1 in symbol 13 of slot n+1) in a first symbol of the second slot, and can transmit (e.g., repeat) the second SRS using the second SRS port (e.g., repeated port 2 in symbol 14 of slot n+1) in a second symbol of the second slot.

[0083] In example 700, the symbol number (or symbol index) used for SRS transmissions on a particular port is different between the first slot and the second slot. For example, the SRS transmission on port 1 occurs in symbol 14 of slot n, and occurs in symbol 13 of slot n+1. Similarly, the SRS transmission on port 2 occurs in symbol 13 of slot n, and occurs in symbol 14 of slot n+1. In some aspects, the symbol number used for SRS transmissions on a particular port can be the same across slots. For example, symbol 13 can be used for SRS transmissions on port 1 in both slot n and slot n+1. Further, although example 700 shows transmission on T = 2 ports in a first slot (slot n), and repeated transmission on T = 2 ports in a second slot (slot n+1), in some aspects, the UE 120 can transmit on a first port (e.g., port 1) in a first slot (e.g., slot n), and can repeat the transmission on the first port in the first slot, and can transmit on a second port (e.g., port 2) in a second slot (e.g., slot n+1), and can repeat the transmission on the second port in the second slot.

[0084] In example 700, base station 110 configures M SRS resources (e.g., M symbols) across different time slots (e.g., for an SRS resource set). For example, for a maximum number of two SRS ports, base station 110 may configure a first SRS resource in a first time slot, and base station 110 may configure a second SRS resource in a second time slot. In this case, the UE may send an SRS transmission on only a single port in both the first time slot and the second time slot. As another example, for a maximum number of four SRS ports (e.g., as Figure 7 ), the base station 110 may configure the first SRS resource and the second SRS resource in the first time slot, and the base station 110 may configure the third SRS resource and the fourth SRS resource in the second time slot. In some aspects, each SRS resource (e.g., each SRS symbol) may correspond to a different SRS port (e.g., for a total of M SRS ports configured across different time slots). In this case, the UE 120 may send SRS on T SRS resources across different time slots (e.g., using T SRS ports and one SRS port for each SRS resource). For example, if the base station 110 configures M SRS resources across two time slots, with each time slot having M / 2 SRS resources, the UE 120 may send SRS on T SRS resources across the two time slots, with each time slot having T / 2 SRS resources. This may be referred to as inter-slot SRS port selection.

[0085] As mentioned above, Figure 7 Provided as an example. Other examples can be found in the Figure 7 Different than described.

[0086] Figure 8 FIG. 8 is a diagram illustrating another example 800 of an adaptive sounding reference signal port configuration according to aspects of the present disclosure. Figure 8 As shown, base station 110 and UE 120 may communicate with each other.

[0087] As shown by reference numeral 805, the base station 110 may transmit an SRS configuration, and the UE 120 may receive the SRS configuration, as described above in conjunction with Figure 4 In some aspects, the SRS configuration may indicate to the UE 120 whether to send an RI report. Alternatively, the indication of whether to send an RI report may be indicated in another configuration and / or another message.

[0088] As shown by reference number 810, the base station 110 can determine whether one or more SRS symbols overlap with one or more PUCCH symbols. For example, the base station 110 can identify one or more symbols configured for SRS transmissions (sometimes referred to as SRS symbols) and can identify one or more symbols in which a PUCCH communication is configured to be transmitted (sometimes referred to as PUCCH symbols). In some aspects, the SRS symbols and / or the PUCCH symbols can be indicated in one or more messages transmitted to the UE 120. For example, the SRS symbols can be indicated in a configuration (e.g., an SRS configuration, an RRC message, and / or the like). Additionally, or alternatively, the PUCCH symbols can be indicated in a configuration (e.g., an RRC message, and / or the like), in downlink control information (DCI), and / or the like. The PUCCH symbols can be part of a short PUCCH (e.g., including a single symbol) or a long PUCCH (e.g., including four symbols). The base station 110 can determine whether the identified SRS symbols overlap with the identified PUCCH symbols. The overlap can be a full overlap (e.g., all SRS symbols overlap with corresponding PUCCH symbols) or a partial overlap (e.g., at least one SRS symbol overlaps with a PUCCH symbol).

[0089] As shown by reference number 815, the base station 110 can transmit, to the UE 120, an indication of whether to transmit an RI report based at least in part on whether the one or more SRS symbols overlap with the one or more PUCCH symbols. The UE 120 can selectively transmit (e.g., can transmit or can refrain from transmitting) the RI report based at least in part on the indication.

[0090] In some aspects, the base station 110 can indicate that the UE 120 is to transmit an RI report based at least in part on determining that the one or more SRS symbols overlap with the one or more PUCCH symbols (e.g., the one or more SRS symbols overlap with a PUCCH symbol, all SRS symbols overlap with corresponding PUCCH symbols, and / or the like). For example, the base station 110 can indicate that the UE 120 is to transmit an RI report based at least in part on determining that the one or more SRS symbols and the one or more PUCCH symbols occur on overlapping symbols of a same carrier (e.g., determining that a PUCCH transmission and an SRS transmission are configured and / or scheduled on one or more overlapping symbols of a same carrier).

[0091] In cases where the base station 110 indicates that the UE 120 is to transmit an RI report, the UE 120 can transmit the RI report to the base station 110 (e.g., in a PUCCH communication, as described above in connection with Figure 3 Figures 4-7 ​The UE 120 can also transmit SRS on an actual number of SRS ports (e.g., which can be less than a maximum number of SRS ports configured by the base station 110). The actual number of SRS ports used by the UE 120 can indicate a rank (e.g., can indicate an RI value) as the actual number of SRS ports can be determined as T = min(M, RI), as described above in connection with Figure 4 However, when one or more SRS symbols overlap with PUCCH symbols, the base station 110 can be unable to determine the actual number of SRS ports used by the UE 120. As a result, the base station 110 can be unable to derive an RI value from the actual number of SRS ports. Accordingly, in such cases, the base station 110 can use an RI report to determine the RI value, as indicated by reference number 830.

[0092] In some aspects, the base station 110 can indicate that the UE 120 does not transmit an RI report based at least in part on determining that the one or more SRS symbols do not overlap with the one or more PUCCH symbols (e.g., no SRS symbol overlaps with a PUCCH symbol). For example, the base station 110 can indicate that the UE 120 does not transmit an RI report based at least in part on determining that the one or more SRS symbols (e.g., all SRS symbols) are configured on a first carrier and determining that the one or more PUCCH symbols (e.g., all PUCCH symbols) are configured on a second carrier (e.g., determining that the PUCCH transmission and the SRS transmission are configured and / or scheduled on different carriers). Additionally, or alternatively, the base station 110 can indicate that the UE 120 does not transmit an RI report based at least in part on determining that the one or more SRS symbols and the one or more PUCCH symbols occur on non-overlapping symbols of a same carrier (e.g., determining that the PUCCH transmission and the SRS transmission are configured and / or scheduled on different symbols of a same carrier).

[0093] In cases where the base station 110 indicates that the UE 120 does not transmit an RI report, the UE 120 can refrain from transmitting an RI report to the base station 110, as indicated by reference number 825. As described above in connection with Figures 4-7 The UE 120 can transmit SRS on an actual number of SRS ports (e.g., which can be less than a maximum number of SRS ports configured by the base station 110). As described above, the actual number of SRS ports used by the UE 120 can indicate a rank (e.g., can indicate an RI value). When the SRS symbols do not overlap with the one or more PUCCH symbols, the base station 110 can be able to determine the actual number of SRS ports used by the UE 120 to transmit the SRS (e.g., using the above-described techniques) and determine an RI value based at least in part on the actual number of SRS ports. Figures 4-7The base station 110 can determine the RI value based on the actual number of SRS ports (e.g., using a blank detection of the received SRS), as indicated by reference number 830. For example, the base station 110 can determine that the RI value is equal to the actual number of SRS ports.

[0094] In this way, by forgoing the transmission of the RI report, network resources can be conserved for other communications. In some aspects, if the actual number of SRS ports is less than the maximum number of SRS ports and the UE 120 is configured to transmit the RI report, the UE 120 can use one or more configured SRS resources (e.g., time domain resources, frequency domain resources, and / or the like) to transmit uplink communications other than SRS using SRS ports that are not used for SRS transmissions (e.g., SRS ports that are muted for SRS transmissions). For example, when the UE 120 transmits the RI report, the UE 120 can transmit uplink data communications (e.g., PUSCH communications), uplink control communications (e.g., PUCCH communications), uplink reference signals other than SRS (e.g., DMRS), and / or the like on the muted SRS ports, thereby increasing throughput, reducing latency, improving network performance, and / or the like. However, if the UE 120 does not transmit the RI report, the UE 120 can refrain from reusing the configured SRS resources for uplink communications other than SRS, as this can hinder the base station 110 from determining the actual number of SRS ports and the corresponding RI value.

[0095] As described above, Figure 8 are provided by way of example. Other examples can be utilized in accordance with various aspects of the disclosure. Figure 8 described.

[0096] Figure 9 is a schematic diagram illustrating an example process 900 performed, for example, by a UE, in accordance with aspects of the present disclosure. Example process 900 is an example of a UE (e.g., UE 120 and / or the like) performing operations associated with adaptive sounding reference signal port configuration.

[0097] As Figure 9As shown, in some aspects, process 900 may include receiving an SRS configuration that indicates a maximum number of SRS ports and whether the UE is permitted to determine an actual number of SRS ports to be used for SRS transmission, the actual number of SRS ports being different from the maximum number of SRS ports (block 910). For example, the UE may receive the SRS configuration that indicates a maximum number of SRS ports and whether the UE is permitted to determine an actual number of SRS ports to be used for SRS transmission, the actual number of SRS ports being different from the maximum number of SRS ports, as described above (e.g., using receive processor 258, controller / processor 280, memory 282, etc.).

[0098] like Figure 9 As further shown, in some aspects, process 900 may include determining, based at least in part on the SRS configuration, an actual number of SRS ports to be used for SRS transmission (block 920). For example, the UE may determine, based at least in part on the SRS configuration, an actual number of SRS ports to be used for SRS transmission, as described above (e.g., using receive processor 258, transmit processor 264, controller / processor 280, memory 282, etc.).

[0099] like Figure 9 As further shown, in some aspects, process 900 may include transmitting one or more SRSs using the actual number of SRS ports (block 930). For example, the UE may transmit one or more SRSs using the actual number of SRS ports as described above (e.g., using transmit processor 264, controller / processor 280, memory 282, etc.).

[0100] Process 900 may include additional aspects, such as any single aspect or any combination of aspects described below and / or in association with one or more other processes described elsewhere herein.

[0101] In a first aspect, if the UE is permitted to determine an actual number of SRS ports that is different from the maximum number of SRS ports, the actual number of SRS ports is equal to the configured number of SRS ports for the SRS resource set indicated in the SRS configuration.

[0102] In a second aspect, alone or in combination with the first aspect, an actual number of SRS ports is determined based at least in part on a maximum number of SRS ports and an RI value determined by the UE.

[0103] In a third aspect, alone or in combination with one or more of the first and second aspects, the actual number of SRS ports is equal to the minimum of the maximum number of SRS ports and the RI value.

[0104] In a fourth aspect, alone or in combination with one or more of the first through third aspects, the one or more SRS are transmitted using a same transmit power for each of the actual number of ports.

[0105] In a fifth aspect, alone or in combination with one or more of the first through fourth aspects, the SRS transmissions on the one or more SRS ports are muted if the actual number of SRS ports is less than the maximum number of SRS ports.

[0106] In a sixth aspect, alone or in combination with one or more of the first through fifth aspects, the UE capability indicates that a number of transmit antennas of the UE is equal to a number of receive antennas of the UE, and the maximum number of SRS ports is equal to the number of transmit antennas and equal to the number of receive antennas.

[0107] In a seventh aspect, alone or in combination with one or more of the first through sixth aspects, the maximum number of SRS ports is indicated using an SRS port number parameter of an SRS resource.

[0108] In an eighth aspect, alone or in combination with one or more of the first through seventh aspects, the actual number of SRS ports is less than or equal to the SRS port number parameter of the SRS resource.

[0109] In a ninth aspect, alone or in combination with one or more of the first through eighth aspects, the UE capability indicates that a number of transmit antennas of the UE is less than a number of receive antennas of the UE, and the UE is configured with a number of SRS resources in the set of SRS resources equal to the maximum number of SRS ports.

[0110] In a tenth aspect, alone or in combination with one or more of the first through ninth aspects, different SRS resources of the number of SRS resources occur in different symbols of a same slot, and the one or more SRS are transmitted in the different SRS resources using different SRS ports.

[0111] In an eleventh aspect, alone or in combination with one or more of the first through tenth aspects, different SRS resources of the number of SRS resources occur in different slots, and the one or more SRS are transmitted in the different SRS resources using different SRS ports.

[0112] In a twelfth aspect, alone or in combination with one or more of the first through eleventh aspects, the process 900 includes receiving an indication of whether to transmit a RI report, and selectively transmitting the RI report based at least in part on the indication.

[0113] In a thirteenth aspect, alone or in combination with one or more of the first through twelfth aspects, the indication indicates to transmit the RI report when one or more SRS symbols overlap with one or more physical uplink control channel symbols; or indicates not to transmit the RI report when the SRS symbols do not overlap with the physical uplink control channel symbols.

[0114] In a fourteenth aspect, alone or in combination with one or more of the first through thirteenth aspects, when the actual number of SRS ports is less than the maximum number of SRS ports and the UE is configured to transmit a rank indicator report, the one or more muted SRS resources are used to transmit uplink communications other than SRS.

[0115] In a fifteenth aspect, alone or in combination with one or more of the first through fourteenth aspects, the actual number of SRS ports is equal to a maximum of the maximum number of SRS ports and the RI value.

[0116] In a sixteenth aspect, alone or in combination with one or more of the first through fifteenth aspects, if the actual number of SRS ports is equal to the maximum number of SRS ports, the SRS transmission is repeated on one or more SRS ports.

[0117] Although Figure 9 Example blocks of the process 900 are illustrated, but in some aspects, the process 900 can include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in FIG. 9. Additionally or alternatively, two or more of the blocks of the process 900 can be performed concurrently. Figure 10

[0118] Figure 10 is a schematic diagram illustrating an example process 1000 that is performed, for example, by a base station, in accordance with aspects of the present disclosure. Example process 1000 is an example of a base station (e.g., base station 110 and / or the like) performing operations associated with adaptive sounding reference signal port configuration.

[0119] As Figure 10 In some aspects, as shown, the process 1000 can include transmitting, to a UE, an SRS configuration indicating a maximum number of SRS ports allowed for the UE and that the UE is permitted to determine an actual number of SRS ports to use for SRS transmissions that is different from the maximum number of SRS ports (block 1010). For example, the base station can transmit, to a UE, an SRS configuration indicating a maximum number of SRS ports allowed for the UE and that the UE is permitted to determine an actual number of SRS ports to use for SRS transmissions that is different from the maximum number of SRS ports, as described above (e.g., using transmit processor 220, controller / processor 240, memory 242, and / or the like).​

[0120] As Figure 10 Further as

[0121] As Figure 10 Further as

[0122] Process 1000 can include additional aspects, such as any single aspect or any combination of aspects described below and / or in connection with one or more other processes described elsewhere herein.

[0123] In a first aspect, process 1000 includes determining an RI value based at least in part on an actual number of SRS ports used by the UE for SRS transmissions when the indication indicates not to transmit the RI report.

[0124] In a second aspect, alone or in combination with the first aspect, the RI value is equal to the actual number of SRS ports.

[0125] In a third aspect, alone or in combination with the first and second aspects, the indication indicates not to transmit the RI report based at least in part on a determination that the one or more SRS symbols do not overlap the one or more PUCCH symbols.

[0126] In a fourth aspect, alone or in combination with one or more of the first through third aspects, the indication indicates to transmit the RI report based at least in part on a determination that the one or more SRS symbols overlap the one or more PUCCH symbols.

[0127] In a fifth aspect, alone or in combination with one or more of the first through fourth aspects, the indication indicates not to transmit the RI report based at least in part on a determination that the one or more SRS symbols are configured on a first carrier and the one or more PUCCH symbols are configured on a second carrier.

[0128] In a sixth aspect, alone or in combination with one or more of the first through fifth aspects, the indication indicates not to transmit the RI report based at least in part on a determination that the one or more SRS symbols and the one or more PUCCH symbols occur on non-overlapping symbols of a same carrier.

[0129] In a seventh aspect, alone or in combination with one or more of the first through sixth aspects, the indication indicates to transmit the RI report based at least in part on a determination that the one or more SRS symbols and the one or more PUCCH symbols occur on overlapping symbols of a same carrier.

[0130] Although Figure 10 The example blocks of process 1000 are illustrated in a particular order, but in some aspects, the process 1000 can include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in the example. Additionally or alternatively, two or more of the blocks of the process 1000 can be performed concurrently. ​ The foregoing disclosure provides illustration and description, but is not intended to be exhaustive or to limit the aspects to the precise form disclosed. Modifications and variations can be possible in light of the above disclosure or from practicing of the aspects.

[0131] As used herein, the term “component” is intended to be broadly interpreted to include hardware, firmware, and / or combinations of hardware and software. As used herein, a processor is implemented in hardware, firmware, and / or combinations of hardware and software.

[0132] As used herein, meeting a threshold value can refer to a value being greater than the threshold value, greater than or equal to the threshold value, less than the threshold value, less than or equal to the threshold value, equal to the threshold value, not equal to the threshold value, etc., depending on the context.

[0133] It will be apparent that systems and / or methods, described herein, can be implemented in different forms of hardware, firmware, and / or a combination of hardware and software. The actual specialized control hardware or software code used to implement these systems and / or methods is not limiting of the aspects. Thus, the operation and behavior of the systems and / or methods were described herein without reference to specific software code — it being understood that software and hardware can be designed to implement the systems and / or methods based, at least in part, on the description herein.

[0134] It will be apparent that systems and / or methods, described herein, can be implemented in different forms of hardware, firmware, and / or a combination of hardware and software. The actual specialized control hardware or software code used to implement these systems and / or methods is not limiting of the aspects. Thus, the operation and behavior of the systems and / or methods were described herein without reference to specific software code — it being understood that software and hardware can be designed to implement the systems and / or methods based, at least in part, on the description herein.

[0135] Although specific combinations of features are listed in the claims and / or disclosed in the specification, other combinations of the features are also possible. Indeed, many of the features can be combined in ways not specifically recited in the claims and / or disclosed in the specification. Although each dependent claim listed below can stand on its own as a separate invention, the teachings of the aspects herein include each dependent claim in combination with every other claim in the claim set. A phrase referring to “at least one of’ a list of items refers to any combination of those items, including single members. As an example, “at least one of a, b, or c” is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any of the same elements in any order.

[0136] No element, act, or instruction used herein should be construed as critical or essential unless explicitly described as such. Also, as used herein, the articles “a” and “an” are intended to include one or more items, and can be used interchangeably with “one or more.” Furthermore, as used herein, the terms “set” and “group” are intended to include one or more items (e.g., related items, unrelated items, a combination of related and unrelated items, or the like), and can be used interchangeably with “one or more.” Where only one item is intended, the phrase “only one” or similar language is used. Also, as used herein, the terms “has,” “have,” “having,” or the like are intended to be open-ended terms. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.

Claims

1. A method of wireless communication performed by a user equipment (UE), comprising: receiving a sounding reference signal (SRS) configuration, the SRS configuration indicating a maximum number of SRS ports, and the SRS configuration indicating, based at least in part on a value of a bit in the SRS configuration, whether the UE is permitted to determine an actual number of SRS ports to use for SRS transmissions that is different from the maximum number of SRS ports; determining, based at least in part on the SRS configuration, the actual number of SRS ports to use for SRS transmissions, wherein the actual number of SRS ports to use for SRS transmissions indicates a rank indicator (RI) value; transmitting one or more SRSs using the actual number of SRS ports; receiving an indication of whether to transmit a rank indicator (RI) report; and selectively transmitting the RI report based at least in part on the indication, wherein the indication indicates that the RI report is to be transmitted when one or more SRS symbols overlap one or more physical uplink control channel symbols, or that the RI report is not to be transmitted when SRS symbols do not overlap physical uplink control channel symbols.

2. The method of claim 1, wherein if the UE is not permitted to determine an actual number of SRS ports that is different from the maximum number of SRS ports, the actual number of SRS ports is equal to a configured number of SRS ports for a SRS resource set indicated in the SRS configuration.

3. The method of claim 1, wherein the actual number of SRS ports is determined based at least in part on the maximum number of SRS ports and the RI value determined by the UE.

4. The method of claim 3, wherein the actual number of SRS ports is equal to a minimum of the maximum number of SRS ports and the RI value.

5. The method of claim 3, wherein the actual number of SRS ports is equal to a maximum of the maximum number of SRS ports and the RI value.

6. The method of claim 1, wherein the one or more SRSs are transmitted using a same transmit power for each of the actual number of ports.

7. The method of claim 1, wherein SRS transmissions on one or more SRS ports are muted if the actual number of SRS ports is less than the maximum number of SRS ports.

8. The method of claim 1, wherein SRS transmissions are repeated on one or more SRS ports if the actual number of SRS ports is equal to the maximum number of SRS ports.

9. The method of claim 1, wherein a UE capability indicates that a number of transmit antennas of the UE is equal to a number of receive antennas of the UE, and wherein the maximum number of SRS ports is equal to the number of transmit antennas and equal to the number of receive antennas.

10. The method of claim 1, wherein the maximum number of SRS ports is indicated using an SRS port number parameter of an SRS resource.

11. The method of claim 10, wherein an actual number of the SRS ports is less than or equal to the SRS port number parameter of the SRS resource.

12. The method of claim 1, wherein a UE capability indicates a number of transmit antennas of the UE is less than a number of receive antennas of the UE, and wherein the UE is configured with a number of SRS resources in a SRS resource set equal to a maximum number of the SRS ports.

13. The method of claim 12, wherein different SRS resources of the number of SRS resources occur in different symbols of a same slot, and wherein the one or more SRSs are transmitted in the different SRS resources using different SRS ports.

14. The method of claim 12, wherein different SRS resources of the number of SRS resources occur in different slots, and wherein the one or more SRSs are transmitted in the different SRS resources using different SRS ports.

15. The method of claim 1, wherein when an actual number of the SRS ports is less than a maximum number of the SRS ports and the UE is configured to transmit a rank indicator report, one or more muted SRS resources are used to transmit uplink communications other than SRS.

16. A method of wireless communication performed by a network entity, comprising: transmitting, to a user equipment (UE), a sounding reference signal (SRS) configuration that indicates a maximum number of SRS ports allowed for the UE, and that indicates, based at least in part on a value of a bit in the SRS configuration, that the UE is permitted to determine an actual number of SRS ports to use for SRS transmissions that is different from the maximum number of SRS ports, wherein the actual number of SRS ports to use for SRS transmissions indicates a rank indicator (RI) value; determining whether one or more SRS symbols overlap one or more physical uplink control channel (PUCCH) symbols; and transmitting, to the UE, an indication of whether to transmit a rank indicator (RI) report based at least in part on whether the one or more SRS symbols overlap the one or more PUCCH symbols, wherein the indication indicates not to transmit the RI report based at least in part on a determination that the one or more SRS symbols do not overlap the one or more PUCCH symbols, and wherein the indication indicates to transmit the RI report based at least in part on a determination that the one or more SRS symbols overlap the one or more PUCCH symbols.

17. The method of claim 16, further comprising: determining the RI value based at least in part on the actual number of SRS ports used by the UE for SRS transmissions when the indication indicates not to transmit the RI report.

18. The method of claim 17, wherein the RI value is equal to the actual number of SRS ports.

19. The method of claim 16, wherein, The determination that the one or more SRS symbols do not overlap with the one or more PUCCH symbols is a determination that the one or more SRS symbols are configured on a first carrier and the one or more PUCCH symbols are configured on a second carrier.

20. The method of claim 16, wherein, The determination that the one or more SRS symbols do not overlap with the one or more PUCCH symbols is a determination that the one or more SRS symbols and the one or more PUCCH symbols occur on non-overlapping symbols of a same carrier.

21. The method of claim 16, wherein, The determination that the one or more SRS symbols overlap with the one or more PUCCH symbols is a determination that the one or more SRS symbols and the one or more PUCCH symbols occur on overlapping symbols of a same carrier.

22. A user equipment (UE) for wireless communication, comprising: a memory; and one or more processors operatively coupled to the memory, the memory and the one or more processors configured to: receive a sounding reference signal (SRS) configuration, the SRS configuration indicating a maximum number of SRS ports, and the SRS configuration indicating whether the UE is permitted to determine an actual number of SRS ports to use for SRS transmissions that is different from the maximum number of SRS ports based at least in part on a value of a bit in the SRS configuration; determine the actual number of SRS ports to use for SRS transmissions based at least in part on the SRS configuration, wherein the actual number of SRS ports to use for SRS transmissions indicates a rank indicator (RI) value; and transmit one or more SRSs using the actual number of SRS ports; receive an indication of whether to transmit a rank indicator (RI) report; and selectively transmit the RI report based at least in part on the indication, wherein the indication indicates that the RI report is to be transmitted when one or more SRS symbols overlap with one or more physical uplink control channel symbols, or that the RI report is not to be transmitted when SRS symbols do not overlap with physical uplink control channel symbols.

23. The UE of claim 22, wherein if the UE is not permitted to determine an actual number of SRS ports that is different from the maximum number of SRS ports, the actual number of SRS ports is equal to a configured number of SRS ports for a SRS resource set indicated in the SRS configuration.

24. The UE of claim 22, wherein the actual number of SRS ports is determined based at least in part on the maximum number of SRS ports and the RI value determined by the UE.

25. The UE of claim 22, wherein the one or more SRSs are transmitted using a same transmit power for each of the actual number of ports.

26. A network entity for wireless communication, comprising: a memory; and one or more processors operatively coupled to the memory, the memory and the one or more processors configured to: transmitting a sounding reference signal (SRS) configuration to a user equipment (UE), the SRS configuration indicating a maximum number of SRS ports allowed for the UE, and the SRS configuration indicating, based at least in part on a value of a bit in the SRS configuration, that the UE is permitted to determine an actual number of SRS ports to use for SRS transmissions that is different from the maximum number of SRS ports, the actual number of SRS ports to use for SRS transmissions indicating a rank indicator (RI) value; determining whether one or more SRS symbols overlap one or more physical uplink control channel (PUCCH) symbols; and transmitting, to the UE, an indication of whether to transmit a rank indicator (RI) report based at least in part on whether the one or more SRS symbols overlap the one or more PUCCH symbols, wherein the indication indicates not to transmit the RI report based at least in part on a determination that the one or more SRS symbols do not overlap the one or more PUCCH symbols, and wherein the indication indicates to transmit the RI report based at least in part on a determination that the one or more SRS symbols overlap the one or more PUCCH symbols.

27. A computer readable medium having program code recorded thereon, wherein, The program code can be executed by one or more processors, to cause the one or more processors to carry out the method according to any one of claims 1 to 15.

28. An apparatus for wireless communication, the apparatus comprising means for performing the method according to any one of claims 1 to 15.

29. A computer program product comprising computer readable instructions executable by a processor to cause the processor to perform the method according to any one of claims 1 to 15.

30. A computer readable medium having program code recorded thereon, wherein, The program code can be executed by one or more processors, to cause the one or more processors to carry out the method according to any one of claims 16 to 21.

31. An apparatus for wireless communication, the apparatus comprising means for performing the method according to any one of claims 16 to 21.

32. A computer program product comprising computer readable instructions executable by a processor to cause the processor to perform the method according to any one of claims 16 to 21.

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