WO2022061730A1

WO2022061730A1 - Sounding reference signal (srs) uplink power control with partial frequency sounding

Info

Publication number: WO2022061730A1
Application number: PCT/CN2020/117803
Authority: WO
Inventors: Muhammad Sayed Khairy Abdelghaffar; Yu Zhang; Alexandros MANOLAKOS; Runxin WANG; Pinar Sen
Original assignee: Qualcomm Incorporated
Priority date: 2020-09-25
Filing date: 2020-09-25
Publication date: 2022-03-31

Abstract

Wireless communications systems and methods related to power control associated with partial frequency sounding are provided. In some aspects, a user equipment (UE) may receive, from a base station (BS), an indication to use a portion of configured sounding reference signal (SRS) frequency resources for transmitting an SRS from the UE to the BS. The UE may further determine, in response to receiving the indication, a first SRS transmission power level for transmitting the SRS from the UE to the BS using the portion of the configured SRS frequency resources.

Description

SOUNDING REFERENCE SIGNAL (SRS) UPLINK POWER CONTROL WITH PARTIAL FREQUENCY SOUNDING

Muhammad Sayed Khairy Abdelghaffar, Yu Zhang, Alexandros Manolakos, Runxin Wang, Pinar Sen

TECHNICAL FIELD

The technology described below relates generally to wireless communication systems, and more particularly to sounding reference signal (SRS) transmission power control for partial frequency sounding.

INTRODUCTION

Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power) . A wireless multiple-access communications system may include a number of base stations (BSs) , each simultaneously supporting communications for multiple communication devices (e.g., user equipment (UE) ) .

To meet the growing demands for expanded mobile broadband connectivity, wireless communication technologies are advancing from the long term evolution (LTE) technology to a next generation new radio (NR) technology, which may be referred to as 5 ^th Generation (5G) . For example, NR is designed to provide a lower latency, a higher bandwidth or a higher throughput, and a higher reliability than LTE. NR is designed to operate over a wide array of spectrum bands, for example, from low-frequency bands below about 1 gigahertz (GHz) and mid-frequency bands from about 1 GHz to about 6 GHz, to high-frequency bands such as millimeter wave (mmWave) bands. NR is also designed to operate across different spectrum types, from licensed spectrum to unlicensed and shared spectrum.

NR may allow for channel quality measurements and beam management with the use of sounding reference signals (SRSs) that are transmitted by UEs and received by BSs. A BS to which a UE is attached may schedule the transmission of the SRSs by the UE and further indicate to the UE the resources that the UE may use in transmitting the SRSs. In some cases, the BS may configure the resources to be used for transmitting the SRSs. The BS may then use these SRSs, for example, determining uplink (UL) channel and/or downlink (DL) channel characteristics.

BRIEF SUMMARY OF SOME EXAMPLES

The following summarizes some aspects of the present disclosure to provide a basic understanding of the discussed technology. This summary is not an extensive overview of all contemplated features of the disclosure and is intended neither to identify key or critical elements of all aspects of the disclosure nor to delineate the scope of any or all aspects of the disclosure. Its sole purpose is to present some concepts of one or more aspects of the disclosure in summary form as a prelude to the more detailed description that is presented later.

For example, in an aspect of the disclosure, a method of wireless communication includes receiving, from a base station (BS) , an indication to use a portion of configured sounding reference signal (SRS) frequency resources for transmitting an SRS from the UE to the BS; and determining, in response to the receiving the indication, a first SRS transmission power level for transmitting the SRS from the UE to the BS using the portion of the configured SRS frequency resources.

In an additional aspect of the disclosure, a method of wireless communication performed by a base station (BS) , the method includes transmitting, to a user equipment (UE) , an indication to use a portion of configured sounding reference signal (SRS) frequency resources for transmitting an SRS from the UE to the BS; and receiving, from the UE using the portion of the configured SRS frequency resources, the SRS at a first SRS transmission power level.

In an additional aspect of the disclosure, a user equipment (UE) , includes a transceiver configured to receive, from a base station (BS) , an indication to use a portion of configured sounding reference signal (SRS) frequency resources for transmitting an SRS from the UE to the BS; and a processor configured to determine, in response to the receiving the indication, a first SRS transmission power level for transmitting the SRS from the UE to the BS using the portion of the configured SRS frequency resources.

In an additional aspect of the disclosure, a base station (BS) , includes a processor; and a transceiver configured to transmit, to a user equipment (UE) , an indication to use a portion of configured sounding reference signal (SRS) frequency resources for transmitting an SRS from the UE to the BS. The transceiver can be further configured to receive, from the UE using the portion of the configured SRS frequency resources, the SRS at a first SRS transmission power level.

In an additional aspect of the disclosure, a non-transitory computer-readable medium having program code recorded thereon, the program code includes code for causing a user equipment (UE) to receive, from a base station (BS) , an indication to use a portion of configured sounding reference signal (SRS) frequency resources for transmitting an SRS from the UE to the BS; and code for causing the UE to determine, in response to the receiving the indication, a first SRS transmission power level for transmitting the SRS from the UE to the BS using the portion of the configured SRS frequency resources.

In an additional aspect of the disclosure, a non-transitory computer-readable medium having program code recorded thereon, the program code includes code for causing a base station (BS) to transmit, to a user equipment (UE) , an indication to use a portion of configured sounding reference signal (SRS) frequency resources for transmitting an SRS from the UE to the BS; and code for causing the BS to receive, from the UE using the portion of the configured SRS frequency resources, the SRS at a first SRS transmission power level.

In an additional aspect of the disclosure, a user equipment (UE) , includes means for receiving, from a base station (BS) , an indication to use a portion of configured sounding reference signal (SRS) frequency resources for transmitting an SRS from the UE to the BS; and means for determining, in response to the receiving the indication, a first SRS transmission power level for transmitting the SRS from the UE to the BS using the portion of the configured SRS frequency resources.

In an additional aspect of the disclosure, a base station (BS) , includes means for transmitting, to a user equipment (UE) , an indication to use a portion of configured sounding reference signal (SRS) frequency resources for transmitting an SRS from the UE to the BS; and means for receiving, from the UE using the portion of the configured SRS frequency resources, the SRS at a first SRS transmission power level.

Other aspects, features, and embodiments will become apparent to those of ordinary skill in the art, upon reviewing the following description of specific, exemplary embodiments in conjunction with the accompanying figures. While features may be discussed relative to certain embodiments and figures below, all embodiments can include one or more of the advantageous features discussed herein. In other words, while one or more embodiments may be discussed as having certain advantageous features, one or more of such features may also be used in accordance with the various embodiments discussed herein. In similar fashion, while exemplary embodiments may be discussed below as device, system, or method embodiments it should be understood that such exemplary embodiments can be implemented in various devices, systems, and methods.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a wireless communication network according to some aspects of the present disclosure.

FIG. 2 illustrates a radio frame structure according to some aspects of the present disclosure.

FIG. 3 illustrate example configuration of a UE with one or more SRS resource sets according to some aspects of the present disclosure.

FIG. 4 illustrates a signaling diagram of a method to control the transmission power of partial frequency sounding according to some aspects of the present disclosure.

FIG. 5 is a block diagram of an exemplary UE according to some aspects of the present disclosure.

FIG. 6 is a block diagram of an exemplary base station (BS) according to some aspects of the present disclosure.

FIG. 7 is a flow diagram of a wireless communication method according to some aspects of the present disclosure.

FIG. 8 is a flow diagram of a wireless communication method according to some aspects of the present disclosure.

DETAILED DESCRIPTION

The detailed description set forth below, in connection with the appended drawings, is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of the various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

This disclosure relates generally to wireless communications systems, also referred to as wireless communications networks. In various embodiments, the techniques and apparatus may be used for wireless communication networks such as code division multiple access (CDMA) networks, time division multiple access (TDMA) networks, frequency division multiple access (FDMA) networks, orthogonal FDMA (OFDMA) networks, single-carrier FDMA (SC-FDMA) networks, LTE networks, Global System for Mobile Communications (GSM) networks, 5 ^th Generation (5G) or new radio (NR) networks, as well as other communications networks. As described herein, the terms “networks” and “systems” may be used interchangeably.

An OFDMA network may implement a radio technology such as evolved UTRA (E-UTRA) , Institute of Electrical and Electronics Engineers (IEEE) 802.11, IEEE 802.16, IEEE 802.20, flash-OFDM and the like. UTRA, E-UTRA, and GSM are part of universal mobile telecommunication system (UMTS) . In particular, long term evolution (LTE) is a release of UMTS that uses E-UTRA. UTRA, E-UTRA, GSM, UMTS and LTE are described in documents provided from an organization named “3rd Generation Partnership Project” (3GPP) , and cdma2000 is described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2) . These various radio technologies and standards are known or are being developed. For example, the 3rd Generation Partnership Project (3GPP) is a collaboration between groups of telecommunications associations that aims to define a globally applicable third generation (3G) mobile phone specification. 3GPP long term evolution (LTE) is a 3GPP project which was aimed at improving the UMTS mobile phone standard. The 3GPP may define specifications for the next generation of mobile networks, mobile systems, and mobile devices. The present disclosure is concerned with the evolution of wireless technologies from LTE, 4G, 5G, NR, and beyond with shared access to wireless spectrum between networks using a collection of new and different radio access technologies or radio air interfaces.

In particular, 5G networks contemplate diverse deployments, diverse spectrum, and diverse services and devices that may be implemented using an OFDM-based unified, air interface. In order to achieve these goals, further enhancements to LTE and LTE-A are considered in addition to development of the new radio technology for 5G NR networks. The 5G NR will be capable of scaling to provide coverage (1) to a massive Internet of things (IoTs) with a Ultra-high density (e.g., ～1M nodes/km ²) , ultra-low complexity (e.g., ～10s of bits/sec) , ultra-low energy (e.g., ～10+ years of battery life) , and deep coverage with the capability to reach challenging locations; (2) including mission-critical control with strong security to safeguard sensitive personal, financial, or classified information, ultra-high reliability (e.g., ～99.9999%reliability) , ultra-low latency (e.g., ～ 1 ms) , and users with wide ranges of mobility or lack thereof; and (3) with enhanced mobile broadband including extreme high capacity (e.g., ～ 10 Tbps/km ²) , extreme data rates (e.g., multi-Gbps rate, 100+ Mbps user experienced rates) , and deep awareness with advanced discovery and optimizations.

A 5G NR communication system may be implemented to use optimized OFDM-based waveforms with scalable numerology and transmission time interval (TTI) . Additional features may also include having a common, flexible framework to efficiently multiplex services and features with a dynamic, low-latency time division duplex (TDD) /frequency division duplex (FDD) design; and with advanced wireless technologies, such as massive multiple input, multiple output (MIMO) , robust millimeter wave (mmWave) transmissions, advanced channel coding, and device-centric mobility. Scalability of the numerology in 5G NR, with scaling of subcarrier spacing, may efficiently address operating diverse services across diverse spectrum and diverse deployments. For example, in various outdoor and macro coverage deployments of less than 3GHz FDD/TDD implementations, subcarrier spacing may occur with 15 kHz, for example over 5, 10, 20 MHz, and the like bandwidth (BW) . For other various outdoor and small cell coverage deployments of TDD greater than 3 GHz, subcarrier spacing may occur with 30 kHz over 80/100 MHz BW. For other various indoor wideband implementations, using a TDD over the unlicensed portion of the 5 GHz band, the subcarrier spacing may occur with 60 kHz over a 160 MHz BW. Finally, for various deployments transmitting with mmWave components at a TDD of 28 GHz, subcarrier spacing may occur with 120 kHz over a 500 MHz BW.

The scalable numerology of the 5G NR facilitates scalable TTI for diverse latency and quality of service (QoS) requirements. For example, shorter TTI may be used for low latency and high reliability, while longer TTI may be used for higher spectral efficiency. The efficient multiplexing of long and short TTIs to allow transmissions to start on symbol boundaries. 5G NR also contemplates a self-contained integrated subframe design with uplink (UL) /downlink (DL) scheduling information, data, and acknowledgement in the same subframe. The self-contained integrated subframe supports communications in unlicensed or contention-based shared spectrum, adaptive UL/downlink that may be flexibly configured on a per-cell basis to dynamically switch between UL and DL to meet the current traffic needs.

Various other aspects and features of the disclosure are further described below. It should be apparent that the teachings herein may be embodied in a wide variety of forms and that any specific structure, function, or both being disclosed herein is merely representative and not limiting. Based on the teachings herein one of an ordinary level of skill in the art should appreciate that an aspect disclosed herein may be implemented independently of any other aspects and that two or more of these aspects may be combined in various ways. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, such an apparatus may be implemented or such a method may be practiced using other structure, functionality, or structure and functionality in addition to or other than one or more of the aspects set forth herein. For example, a method may be implemented as part of a system, device, apparatus, and/or as instructions stored on a computer readable medium for execution on a processor or computer. Furthermore, an aspect may comprise at least one element of a claim.

In a wireless communication network, a BS may configure parameters of the SRS and transmit these parameters to a user equipment (UE) via RRC messages, for example. For instance, the BS may provide an indication to the UE of the SRS frequency resources (e.g., configured SRS frequency resources) available to the UE for sounding. Before transmitting an SRS (e.g., sounding) using these indicated configured SRS frequency resources, the UE may determine a transmission power suitable for transmitting a first SRS based on the number of SRS frequency resources indicated available (e.g., configured and allocated) to the UE. Subsequently, the UE may transmit a second SRS using only a partial set of the SRS frequency resources available to the UE (e.g., a portion of the configured SRS frequency resources) . For instance, the UE may transmit the second SRS using the partial set of the configured SRS frequency resources in response to receiving an indication from the BS to utilize the partial set of configured SRS frequency resources, which may increase network capacity. However, for a given transmission power level, sounding (e.g., transmitting the second SRS) over the partial set of configured SRS frequency resources may result in different transmission characteristics (e.g., signal-to-noise ratios, power spectral density, and/or the like) than sounding over the full set of the configured SRS frequency resources.

Accordingly, aspects of the present disclosure relate to power control for sounding over a partial set of configured SRS frequency resources (e.g., partial frequency sounding) . For instance, the power control may involve determining the transmission (e.g., uplink) power level to transmit a SRS using a partial set of configured SRS frequency resources. In some aspects, the UE may be configured to transmit the second SRS with the transmission power level used for the first SRS and/or a transmission power level calculated based on the total number of configured SRS frequency resources indicated as available to the UE, which may improve the signal-to-noise ratio (SNR) of the transmission in comparison with transmission of the first SRS. In some aspects, the UE may transmit the second SRS using a transmission power level calculated based on the number of configured SRS frequency resources in the partial set of the configured SRS frequency resources. In this way, the UE may reduce the power used to transmit the second SRS in comparison with the first SRS, which may reduce power consumption at the UE and may maintain the same power spectral density (PSD) for transmission of the first and second SRS. Further, in some aspects, the UE may be configured with a power control mode corresponding to partial frequency sounding (e.g., sounding over the partial set of the configured SRS frequency resources) . When operating according to this power control mode, the UE may transmit SRSs with a fixed transmission power level, which may be determined based on a semi-static RRC configuration. For instance, the UE may be configured to, in this mode of operation, transmit at a maximum transmission power level that the UE is capable of using for SRS transmission. Thus, the UE may be configured to perform partial frequency sounding using a transmission power level that may be configured to provide certain advantages, such as an improved SNR, a relatively constant PSD, simplicity of implementation, and/or the like.

For instance, in some aspects, the UE may receive, from the BS, an indication to use a portion of configured SRS frequency resources (e.g., a partial set of configured SRS frequency resources) for transmitting an SRS from the UE to the BS. Moreover, the UE may determine, in response to receiving the indication, a first SRS transmission power level for transmitting the SRS to the BS using the portion of the configured SRS frequency resources. In some aspects, the UE may determine the first SRS transmission power level based on the number of SRS frequency resources included in the configured SRS frequency resources, and in other aspects, the UE may determine the first SRS transmission power level based on the number of SRS frequency resources included in the portion of the configured SRS frequency resources. Further, in some aspects, the first SRS transmission power level may be semi-statically configured by the BS. The BS may semi-statically configure the first SRS transmission power level using an RRC message, for example. Additionally or alternatively, the first SRS transmission power level may be a maximum transmission power level of the UE. For instance, the first SRS transmission power level may correspond to a fixed transmission power level corresponding to a power control mode associated with partial frequency sounding.

In some aspects, the UE may transmit, to the BS, the first SRS using the portion of the configured SRS frequency resources and the first SRS transmission power level determined according to one or more of the techniques described above. Further, in some aspects, the UE may transmit, to the BS, a power headroom (PHR) report. The power headroom report may include a flag indicating that the UE is configured to operate with partial frequency sounding (e.g., to use the portion of the full set of SRS frequency resources to transmit the first SRS) . Alternatively, the flag may indicate that the UE is configured to operate with full frequency sounding, which may correspond to the UE transmitting a second SRS using the configured SRS frequency resources. In some aspects, the PHR report may include a difference between the first transmission power level and a second transmission power level used to transmit the second SRS with the configured SRS frequency resources. Moreover, in some aspects, the UE may be configured to transmit the PHR report in a medium access control-control element (MAC-CE) .

Aspects of the present disclosure can provide several benefits. For example, as noted above, transmitting an SRS over partial set of the configured SRS frequency resources using a transmission power level determined based on the total number of configured SRS frequency resources designated for a UE may increase the SNR associated with the transmitted SRS. Further, by transmitting an SRS over a partial set of the configured SRS frequency resources (e.g., a subset of the configured SRS frequency resources) using a transmission power level determined based on the number of SRS frequency resources within the partial set of the configured SRS frequency resources may maintain the PSD associated with the transmitted SRS below a certain threshold. For example, the PSD associated with the transmitted SRS may substantially match a PSD associated with an SRS transmitted by the UE using each of the available configured SRS frequency resources (e.g., the full set of the configured SRS frequency resources) and a transmission power level calculated based on the each of the available configured SRS frequency resources. In this way, the interference caused by the transmitted SRS at other wireless communication devices (e.g., at other UEs) may be minimized. In addition, using transmission power level determined based on the number of SRS frequency resources within the partial set of the configured SRS frequency resources may reduce the power consumed at the UE. Moreover, in some aspects, implementing a power control mode for partial frequency sounding that utilizes a fixed transmission power level may reduce implementation complexity, as calculation of a suitable transmission power level at the UE for an SRS transmission may be avoided. Accordingly, the present disclosure can facilitate power control associated with partial frequency sounding at a UE.

While aspects and embodiments are described in this application by illustration to some examples, those skilled in the art will understand that additional implementations and use cases may come about in many different arrangements and scenarios. Innovations described herein may be implemented across many differing platform types, devices, systems, shapes, sizes, packaging arrangements. For example, embodiments and/or uses may come about via integrated chip embodiments and other non-module-component based devices (e.g., end-user devices, vehicles, communication devices, computing devices, industrial equipment, retail/purchasing devices, medical devices, AI-enabled devices, etc. ) . While some examples may or may not be specifically directed to use cases or applications, a wide assortment of applicability of described innovations may occur. Implementations may range a spectrum from chip-level or modular components to non-modular, non-chip-level implementations and further to aggregate, distributed, or OEM devices or systems incorporating one or more aspects of the described innovations. In some practical settings, devices incorporating described aspects and features may also necessarily include additional components and features for implementation and practice of claimed and described embodiments. For example, transmission and reception of wireless signals necessarily includes a number of components for analog and digital purposes (e.g., hardware components including antenna, RF-chains, power amplifiers, modulators, buffer, processor (s) , interleaver, adders/summers, etc. ) . It is intended that innovations described herein may be practiced in a wide variety of devices, chip-level components, systems, distributed arrangements, end-user devices, etc. of varying sizes, shapes, and constitution.

FIG. 1 illustrates a wireless communication network 100 according to some aspects of the present disclosure. The network 100 may be a 5G network. The network 100 includes a number of base stations (BSs) 105 (individually labeled as 105a, 105b, 105c, 105d, 105e, and 105f) and other network entities. A BS 105 may be a station that communicates with UEs 115 and may also be referred to as an evolved node B (eNB) , a next generation eNB (gNB) , an access point, and the like. Each BS 105 may provide communication coverage for a particular geographic area. In 3GPP, the term “cell” can refer to this particular geographic coverage area of a BS 105 and/or a BS subsystem serving the coverage area, depending on the context in which the term is used.

A BS 105 may provide communication coverage for a macro cell or a small cell, such as a pico cell or a femto cell, and/or other types of cell. A macro cell generally covers a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscriptions with the network provider. A small cell, such as a pico cell, would generally cover a relatively smaller geographic area and may allow unrestricted access by UEs with service subscriptions with the network provider. A small cell, such as a femto cell, would also generally cover a relatively small geographic area (e.g., a home) and, in addition to unrestricted access, may also provide restricted access by UEs having an association with the femto cell (e.g., UEs in a closed subscriber group (CSG) , UEs for users in the home, and the like) . A BS for a macro cell may be referred to as a macro BS. A BS for a small cell may be referred to as a small cell BS, a pico BS, a femto BS or a home BS. In the example shown in FIG. 1, the BSs 105d and 105e may be regular macro BSs, while the BSs 105a-105c may be macro BSs enabled with one of three dimension (3D) , full dimension (FD) , or massive MIMO. The BSs 105a-105c may take advantage of their higher dimension MIMO capabilities to exploit 3D beamforming in both elevation and azimuth beamforming to increase coverage and capacity. The BS 105f may be a small cell BS which may be a home node or portable access point. A BS 105 may support one or multiple (e.g., two, three, four, and the like) cells.

The network 100 may support synchronous or asynchronous operation. For synchronous operation, the BSs may have similar frame timing, and transmissions from different BSs may be approximately aligned in time. For asynchronous operation, the BSs may have different frame timing, and transmissions from different BSs may not be aligned in time.

The UEs 115 may be dispersed throughout the wireless network 100, and each UE 115 may be stationary or mobile. UEs can take in a variety of forms and a range of form factors. A UE 115 may also be referred to as a terminal, a mobile station, a subscriber unit, a station, or the like. A UE 115 may be a cellular phone, a personal digital assistant (PDA) , a wireless modem, a wireless communication device, a handheld device, a tablet computer, a laptop computer, a cordless phone, a wireless local loop (WLL) station, or the like. In one aspect, a UE 115 may be a device that includes a Universal Integrated Circuit Card (UICC) . In another aspect, a UE may be a device that does not include a UICC. In some aspects, the UEs 115 that do not include UICCs may also be referred to as IoT devices or internet of everything (IoE) devices. The UEs 115a-115d are examples of mobile smart phone-type devices accessing network 100. A UE 115 may also be a machine specifically configured for connected communication, including machine type communication (MTC) , enhanced MTC (eMTC) , narrowband IoT (NB-IoT) and the like. The UEs 115e-115h are examples of various machines configured for communication that access the network 100. The UEs 115i-115k are examples of vehicles equipped with wireless communication devices configured for communication that access the network 100. A UE 115 may be able to communicate with any type of the BSs, whether macro BS, small cell, or the like. In FIG. 1, a lightning bolt (e.g., communication links) indicates wireless transmissions between a UE 115 and a serving BS 105, which is a BS designated to serve the UE 115 on the downlink (DL) and/or uplink (UL) , desired transmission between BSs 105, backhaul transmissions between BSs, or sidelink transmissions between UEs 115.

In operation, the BSs 105a-105c may serve the

UEs

115a and 115b using 3D beamforming and coordinated spatial techniques, such as coordinated multipoint (CoMP) or multi-connectivity. The macro BS 105d may perform backhaul communications with the BSs 105a-105c, as well as small cell, the BS 105f. The macro BS 105d may also transmits multicast services which are subscribed to and received by the UEs 115c and 115d. Such multicast services may include mobile television or stream video, or may include other services for providing community information, such as weather emergencies or alerts, such as Amber alerts or gray alerts.

The BSs 105 may also communicate with a core network. The core network may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. At least some of the BSs 105 (e.g., which may be an example of a gNB or an access node controller (ANC) ) may interface with the core network through backhaul links (e.g., NG-C, NG-U, etc. ) and may perform radio configuration and scheduling for communication with the UEs 115. In various examples, the BSs 105 may communicate, either directly or indirectly (e.g., through core network) , with each other over backhaul links (e.g., X1, X2, etc. ) , which may be wired or wireless communication links.

The network 100 may also support mission critical communications with ultra-reliable and redundant links for mission critical devices, such as the UE 115e, which may be a drone. Redundant communication links with the UE 115e may include links from the macro BSs 105d and 105e, as well as links from the small cell BS 105f. Other machine type devices, such as the UE 115f (e.g., a thermometer) , the UE 115g (e.g., smart meter) , and UE 115h (e.g., wearable device) may communicate through the network 100 either directly with BSs, such as the small cell BS 105f, and the macro BS 105e, or in multi-step-size configurations by communicating with another user device which relays its information to the network, such as the UE 115f communicating temperature measurement information to the smart meter, the UE 115g, which is then reported to the network through the small cell BS 105f. The network 100 may also provide additional network efficiency through dynamic, low-latency TDD/FDD communications, such asV2V, V2X, C-V2X communications between a UE 115i, 115j, or 115k and other UEs 115, and/or vehicle-to-infrastructure (V2I) communications between a UE 115i, 115j, or 115k and a BS 105.

In some implementations, the network 100 utilizes OFDM-based waveforms for communications. An OFDM-based system may partition the system BW into multiple (K) orthogonal subcarriers, which are also commonly referred to as subcarriers, tones, bins, or the like. Each subcarrier may be modulated with data. In some instances, the subcarrier spacing between adjacent subcarriers may be fixed, and the total number of subcarriers (K) may be dependent on the system BW. The system BW may also be partitioned into subbands. In other instances, the subcarrier spacing and/or the duration of TTIs may be scalable.

In some aspects, the BSs 105 can assign or schedule transmission resources (e.g., in the form of time-frequency resource blocks (RB) ) for downlink (DL) and uplink (UL) transmissions in the network 100. DL refers to the transmission direction from a BS 105 to a UE 115, whereas UL refers to the transmission direction from a UE 115 to a BS 105. The communication can be in the form of radio frames. A radio frame may be divided into a plurality of subframes or slots, for example, about 10. Each slot may be further divided into mini-slots. In a FDD mode, simultaneous UL and DL transmissions may occur in different frequency bands. For example, each subframe includes a UL subframe in a UL frequency band and a DL subframe in a DL frequency band. In a TDD mode, UL and DL transmissions occur at different time periods using the same frequency band. For example, a subset of the subframes (e.g., DL subframes) in a radio frame may be used for DL transmissions and another subset of the subframes (e.g., UL subframes) in the radio frame may be used for UL transmissions.

The DL subframes and the UL subframes can be further divided into several regions. For example, each DL or UL subframe may have pre-defined regions for transmissions of reference signals, control information, and data. Reference signals are predetermined signals that facilitate the communications between the BSs 105 and the UEs 115. For example, a reference signal can have a particular pilot pattern or structure, where pilot tones may span across an operational BW or frequency band, each positioned at a pre-defined time and a pre-defined frequency. For example, a BS 105 may transmit cell specific reference signals (CRSs) and/or channel state information –reference signals (CSI-RSs) to enable a UE 115 to estimate a DL channel. Similarly, a UE 115 may transmit sounding reference signals (SRSs) to enable a BS 105 to estimate a UL channel. Control information may include resource assignments and protocol controls. Data may include protocol data and/or operational data. In some aspects, the BSs 105 and the UEs 115 may communicate using self-contained subframes. A self-contained subframe may include a portion for DL communication and a portion for UL communication. A self-contained subframe can be DL-centric or UL-centric. A DL-centric subframe may include a longer duration for DL communication than for UL communication. A UL-centric subframe may include a longer duration for UL communication than for UL communication.

In some aspects, the network 100 may be an NR network deployed over a licensed spectrum. The BSs 105 can transmit synchronization signals (e.g., including a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) ) in the network 100 to facilitate synchronization. The BSs 105 can broadcast system information associated with the network 100 (e.g., including a master information block (MIB) , remaining system information (RMSI) , and other system information (OSI) ) to facilitate initial network access. In some instances, the BSs 105 may broadcast the PSS, the SSS, and/or the MIB in the form of synchronization signal block (SSBs) over a physical broadcast channel (PBCH) and may broadcast the RMSI and/or the OSI over a physical downlink shared channel (PDSCH) .

In some aspects, a UE 115 attempting to access the network 100 may perform an initial cell search by detecting a PSS from a BS 105. The PSS may enable synchronization of period timing and may indicate a physical layer identity value. The UE 115 may then receive a SSS. The SSS may enable radio frame synchronization, and may provide a cell identity value, which may be combined with the physical layer identity value to identify the cell. The PSS and the SSS may be located in a central portion of a carrier or any suitable frequencies within the carrier.

After receiving the PSS and SSS, the UE 115 may receive a MIB. The MIB may include system information for initial network access and scheduling information for RMSI and/or OSI. After decoding the MIB, the UE 115 may receive RMSI and/or OSI. The RMSI and/or OSI may include radio resource control (RRC) information related to random access channel (RACH) procedures, paging, control resource set (CORESET) for physical downlink control channel (PDCCH) monitoring, physical UL control channel (PUCCH) , physical UL shared channel (PUSCH) , power control, and SRS.

After obtaining the MIB, the RMSI and/or the OSI, the UE 115 can perform a random access procedure to establish a connection with the BS 105. The random access procedure (or RACH procedure) may be a single or multiple step process. In some examples, the random access procedure may be a four-step random access procedure. For example, the UE 115 may transmit a random access preamble and the BS 105 may respond with a random access response. The random access response (RAR) may include a detected random access preamble identifier (ID) corresponding to the random access preamble, timing advance (TA) information, a UL grant, a temporary cell-radio network temporary identifier (C-RNTI) , and/or a backoff indicator. Upon receiving the random access response, the UE 115 may transmit a connection request to the BS 105 and the BS 105 may respond with a connection response. The connection response may indicate a contention resolution. In some examples, the random access preamble, the RAR, the connection request, and the connection response can be referred to as message 1 (MSG1) , message 2 (MSG2) , message 3 (MSG3) , and message 4 (MSG4) , respectively. In some examples, the random access procedure may be a two-step random access procedure, where the UE 115 may transmit a random access preamble and a connection request in a single transmission and the BS 105 may respond by transmitting a random access response and a connection response in a single transmission.

After establishing a connection, the UE 115 and the BS 105 can enter a normal operation stage, where operational data may be exchanged. For example, the BS 105 may schedule the UE 115 for UL and/or DL communications. The BS 105 may transmit UL and/or DL scheduling grants to the UE 115 via a PDCCH. Scheduling grants may be transmitted in the form of DL control information (DCI) . The BS 105 may transmit a DL communication signal (e.g., carrying data) to the UE 115 via a PDSCH according to a DL scheduling grant. The UE 115 may transmit a UL communication signal to the BS 105 via a PUSCH and/or PUCCH according to a UL scheduling grant.

In some aspects, the network 100 may operate over a system BW or a component carrier (CC) BW. The network 100 may partition the system BW into multiple BWPs (e.g., portions) . A BS 105 may dynamically assign a UE 115 to operate over a certain BWP (e.g., a certain portion of the system BW) . The assigned BWP may be referred to as the active BWP. The UE 115 may monitor the active BWP for signaling information from the BS 105. The BS 105 may schedule the UE 115 for UL or DL communications in the active BWP. In some aspects, a BS 105 may assign a pair of BWPs within the CC to a UE 115 for UL and DL communications. For example, the BWP pair may include one BWP for UL communications and one BWP for DL communications.

In some aspects, the BS 105 may serve multiple UEs 115 each having one or more transmit antenna elements and/or one or more receive antenna elements. The BS 105 may multiplex multiple UEs 115 for simultaneous communications over different spatial layers. To assist the BS 105 in determining UL channel characteristics, the BS 105 may configure each UE 115 to sound one or more transmit antenna ports of the respective UE 115. Sounding may refer to the transmission of an SRS via one or more antenna ports. The SRS may include a waveform sequence (e.g., predetermined) that are known to the BS 105 and the UE 115. For instance, the SRS may be Zadoff-Chu sequence or any suitable waveform sequence. In some instances, a transmit antenna port at a UE 115 may map to a physical transmit antenna element of the UE 115. In some other instances, a transmit antenna port at a UE 115 may be a virtual antenna port or a logical port created by the UE 115, for example, via precoding. Precoding may include applying different amplitude weights and/or different phased adjustments to signals output by the physical transmit antenna elements of the UE 115 to produce a signal directed towards a certain spatial direction. In some aspects, the network 100 may operate in a TDD mode. The BS 105 may also estimate DL channel characteristics from UL SRSs received from the UEs 115 based on TDD channel reciprocity.

In some aspects, the BS 105 may configure an SRS resource pool for sharing among a group of UEs 115. The SRS resource pool may include a plurality of SRS resources with different quantity of SRS ports. The BS 105 may configure parameters of the SRS semi-statically (e.g., via RRC messages) . Additionally or alternatively, the BS 105 may dynamically trigger or activate a subset of the plurality of SRS resources for a connected UE 115 to transmit an SRS. Further, in some aspects, after the BS 105 activates the subset of the plurality of SRS resources for the connected UE 115, the BS 105 may transmit a request, or an indication, to the UE 115 to reduce the number of SRS resources used to transmit a second SRS (e.g., to transmit using a partial set of SRS resources within the subset of the plurality of SRS resources) . In such aspects, the UE 115 transmit the second SRS with a transmission power level determined based on the request from the BS 105 and/or a configuration of the UE 115. Mechanisms for determining the transmission power level to transmit using a partial set of SRS resources are described in greater detail herein.

FIG. 2 illustrates a radio frame structure 200 according to some aspects of the present disclosure. The radio frame structure 200 may be employed by BSs such as the BSs 105 and UEs such as the UEs 115 in a network such as the network 100 for communications, for example, for the transmission of SRS from the UEs to the BSs. In particular, the BS may communicate with the UE using time-frequency resources configured as shown in the radio frame structure 200. In FIG. 2, the x-axes represent time in some arbitrary units and the y-axes represent frequency in some arbitrary units. The transmission frame structure 200 includes a radio frame 201. The duration of the radio frame 201 may vary depending on the aspects. In an example, the radio frame 201 may have a duration of about ten milliseconds. The radio frame 201 includes M number of slots 202, where M may be any suitable positive integer. In an example, M may be about 10.

Each slot 202 includes a number of subcarriers 204 in frequency and a number of symbols 206 in time. The number of subcarriers 204 and/or the number of symbols 206 in a slot 202 may vary depending on the aspects, for example, based on the channel bandwidth, the subcarrier spacing (SCS) , and/or the cyclic prefix (CP) mode. One subcarrier 204 in frequency and one symbol 206 in time forms one resource element (RE) 212 for transmission. A resource block (RB) 210 is formed from a number of consecutive subcarriers 204 in frequency and a number of consecutive symbols 206 in time. Each slot 202 may be time-partitioned into K number of mini-slots 208. Each mini-slot 208 may include one or more symbols 206. The mini-slots 208 in a slot 202 may have variable lengths. For example, when a slot 202 includes N number of symbols 206, a mini-slot 208 may have a length between one symbol 206 and (N-1) symbols 206. In some aspects, a mini-slot 208 may have a length of about two symbols 206, about four symbols 206, or about seven symbols 206. In some examples, the BS may schedule UE at a frequency-granularity of a resource block (RB) 210 (e.g., including about 12 subcarriers 204) . In an example, a BS (e.g., BS 105 in FIG. 1) may schedule a UE (e.g., UE 115 in FIG. 1) for UL and/or DL communications at a time-granularity of slots 202 or mini-slots 208.

In some aspects, a SRS may span one, two or four consecutive symbols and may be located within the last six symbols of a slot (i.e., in the time domain of the radio frame structure 200 that includes the time and frequency resources) . In the frequency domain, an SRS may have a “comb” structure, i.e., the SRS may be transmitted on every second subcarrier ( “comb-2” ) or fourth ( “comb-4” ) subcarrier. In some aspects, SRS transmissions from different devices may be frequency multiplexed within the same frequency range by assigning different combs corresponding to different frequency offsets. For example, for “comb-2” and for “comb-4” , two SRSs and up to four SRSs, respectively, can be frequency multiplexed. Further, in some aspects, an SRS transmission from a device may be further multiplexed using inter-slot or intra-slot frequency hopping. To that end, the SRS transmission may be transmitted over different subcarriers 204 for different slots 202 within a radio frame 201 and/or for different symbols 206 within a slot 202, respectively.

FIG. 3 illustrates example configuration of a UE with one or more SRS resource sets according to some aspects of the present disclosure. The configuration 300 includes a plurality of SRS resource sets 302 (shown as SRS resource set 0 to SRS resource set N) , each SRS resource set 302 including one or more SRS resources 304, i.e., one or more configured SRSs. Each SRS resource 304 may include time-frequency resources. For instance, each SRS resource 304 may span one or more symbols (e.g., the symbols 206) within a slot (e.g., the slot 202) and may include one or more subcarriers (e.g., the subcarriers 204) or REs (e.g., the REs 212) within each SRS symbol. Additionally, each SRS resource 304 may be configured with one or more SRS ports 306 (e.g., up to four SRS ports) . For instance, each SRS port 306 may be associated with one or more REs within an SRS symbol. A UE (e.g., UE 115) may transmit an SRS in SRS REs that are associated with an SRS port 306 corresponding to a transmit antenna port of the UE, and the SRS can assist the BS (e.g., BS 105) in determining uplink channel state information (UL CSI) and/or downlink channel state information (DL CSI) associated with the UE and/or in performing beam management procedures, facilitating communication with the UE.

In some aspects, each SRS resource set 302 may be associated with a certain resource type. For example, an SRS resource set 302 may have a resource type of periodic, semi-persistent, or aperiodic. An SRS resource set 302 with a periodic resource type may have a configured periodicity and each periodic SRS resource 304 may have a configured symbol offset within a slot. A UE 115 may utilize a periodic SRS resource 304 for periodic SRS transmission. An SRS resource set 302 with a semi-persistent resource type may have a configured periodicity similar to a periodic SRS resource set 302 and each semi-persistent resource 304 may have a configured symbol offset within a slot similar to a periodic SRS resource 304. However, a UE 115 may not transmit an SRS in a semi-persistent SRS resource 304 until the BS 105 triggers an activation (e.g., via MAC-CE) of the SRS resource 304. An SRS resource 304 in an SRS resource set 302 with an aperiodic resource type may be utilized by a UE 115 when the UE 115 receives an explicit trigger (e.g., via DCI) from the BS 105.

As described herein, the term “SRS frequency resource” can refer to an SRS RE included in an SRS resource 304 and/or associated with an SRS port 306 of the SRS resource 304. Further, the terms “configured SRS frequency resources” and “full set of configured SRS frequency resources, ” which may be used interchangeably, can refer to each of the SRS frequency resources (e.g., a full set of SRS frequency resources) configured for use by the UE 115. That is, for example, the configured SRS frequency resources may refer to each of the SRS frequency resources included in the SRS resources of an SRS resource set 302 allocated to and configured for use by the UE 115. On the other hand, the terms “partial set of SRS frequency resources, ” “partial set of the configured SRS frequency resources” and/or “portion of the full set of SRS frequency resources, ” which may be used interchangeably, may refer to a subset of the configured SRS frequency resources allocated for use by the UE 115. Accordingly, a partial set of SRS frequency resources may include fewer SRS frequency resources than the corresponding configured SRS frequency resources.

As described herein, in some instances, the UE 115 may transmit an SRS (e.g., sound) using a full set of configured SRS frequency resources available (e.g., configured and allocated) for use by the UE, which may be referred herein to as “full frequency sounding, ” and in other instances, the UE 115 may transmit an SRS using a partial set of SRS frequency resources, which may be referred to herein as “partial frequency sounding. ” That is, for example, while the full set of configured SRS frequency resources may be configured for use by the UE 115, the UE may transmit an SRS using fewer SRS frequency resources than the full set of configured SRS frequency resources. Further, in some cases, the UE 115 may sound over the full or partial set of SRS frequency resources using a transmission power level determined based in part on a closed-loop power control parameter, as well as the number of frequency resources within the configured SRS frequency resources. For instance, the UE 115 may receive a transmission power control command (TPC) from the BS 105 (e.g., via a DCI transmission) . Subsequently, the UE 115 may sound using a transmission power level determined based on the TPC and the number of frequency SRS resources within the set of configured SRS frequency resources. However, for a given transmission power level, sounding over the partial set of the configured SRS frequency resources may result in different transmission characteristics (e.g., signal-to-noise ratios, power spectral density, and/or the like) than sounding over the each of the configured SRS frequency resources. Accordingly, mechanisms for power control for partial frequency sounding, which may involve determining the transmission power level to transmit using a portion of the configured SRS frequency resources, are described in greater detail herein.

Referring now to FIG. 4, a signaling diagram of an SRS resource configuration and channel sounding method 400 is illustrated, according to some aspects of the present disclosure. The method 400 may be employed by a BS, such as BS 105, and a UE, such as UE 115, to control the transmission power level of partial frequency sounding, as described in greater detail below. Further, the method 400 can be used in conjunction with the radio frame structure 200 of FIG. 2, as well as the configuration 300 of FIG. 3. As illustrated, the method 400 includes a number of enumerated actions, but embodiments of the method 400 may include additional actions before, after, and in between the enumerated actions. In some embodiments, one or more of the enumerated actions may be omitted or performed in a different order.

At action 402, the BS 105 may transmit an indication of an SRS resource configuration to the UE 115. In some aspects, the BS 105 may include the SRS resource configuration within an RRC message, as illustrated. In any case, the indication of the SRS resource configuration may configure and allocate an SRS resource set (e.g., SRS resource set 302) , which may include one more SRS resources (e.g., SRS resources 304) , for use by the UE 115 for transmission of an SRS. To that end, the indication of the SRS resource configuration may configure the UE 115 such that the UE 115 may transmit the SRS using the configured SRS frequency resources included in the SRS resource set.

At action 404, the UE 115 may transmit an SRS (e.g., a first SRS) using the configured SRS frequency resources identified by the BS 105 at action 402 (e.g., within the SRS resource configuration) . More specifically, the UE 115 may transmit the SRS using each of the configured SRS frequency resources available for use by the UE 115 and a transmission power level determined based on the SRS resource configuration (e.g., full TxP) . In some aspects, for example, the UE 115 may compute a transmit power for the SRS transmission based on the number of SRS frequency resources included in the set of the configured SRS frequency resources allocated to the UE 115. For instance, the UE 115 may compute the transmit power, denoted as P _SRS, as shown below:

P _SRS=min [P _cmax, P _{O_SRS} +10×log (2 ^μ·M _SRS) +α _SRS·PL +h] (1)

where P _cmax represents the maximum transmit power configured for the UE, for example, according to a particular communication standard. P _{O_SRS} represents a frequency parameter configured by the BS 105, such as a target power spectral density. M _SRS represents the number of SRS frequency resources (e.g., REs 212) in the set of the configured SRS frequency resources assigned to the UE 115. PL represents estimated path loss. α represents the factor, which may have a value between 0 and 1, to enable or disable fractional power control or cell specific factor, which may be configured by the BS 105. h represents a closed loop component of the power control, for example, received from a transmission power control (TCP) command issued by the BS 105 (e.g., via a DCI transmission) .

Additionally or alternatively, the UE 115 may determine the transmit power for the SRS transmission based on the number of SRS frequency resources included in the set of the configured SRS frequency resources and a PUSCH signal transmission. For instance, one or more of the parameters of equation 1 (e.g., P _cmax , P _{O_SRS} , α _SRS, PL, h, and/or the like) may be associated with corresponding parameters used to determine a transmission power level for the PUSCH signal. Accordingly, if the transmission of the first SRS follows transmission of the PUSCH signal, the UE 115 may determine a respective value of the one or more of the parameters in equation 1, based on the value of the corresponding parameters used to determine the transmission power level for the PUSCH signal. In such cases, the UE 115 may determine the transmission power level to transmit the SRS (e.g., full TxP) in a similar manner to a determination of the transmission power level corresponding to the PUSCH signal, but the UE 115 may update the value of M _SRS, if necessary, to reflect the number of SRS frequency resources in the full set of SRS frequency resources. Moreover, in some cases, the UE 115 may determine that the transmission power level used to transmit the PUSCH signal may be used as the full TxP.

In some aspects, the UE 115 may be configured to continue transmitting subsequent SRSs using the full set of the configured SRS frequency resources and the transmission power level determined above (full TxP) unless and/or until the UE 115 is reconfigured or receives a suitable notification from the BS 105 to alter the transmission power level or the number of configured SRS frequency resources utilized for sounding by the UE 115. To that end, the UE 115 may remain configured for full frequency sounding. Accordingly, the UE 115 may transmit subsequent SRS transmissions using the full set of the configured SRS frequency resources and the full TxP without recalculating or re-evaluating the transmission power level for SRS transmission. Further, while a single SRS is illustrated as being transmitted by the UE at action 404, it may be appreciated that any number of SRSs may be transmitted using the full TxP.

At action 405, the UE 115 may transmit a partial SRS capability report to the BS 105. In some aspects, the partial SRS capability report may indicate to the BS 105 and/or a communication network (e.g., devices attached to the network) , that the UE 115 is capable of performing partial frequency sounding. In particular, the partial SRS capability report may indicate that the UE 115 may transmit an SRS using fewer SRS frequency resources than those included in the configured SRS frequency resources available to the UE 115. The partial capability report may further indicate that the UE 115 may adjust a transmission power level for transmitting the SRS using partial frequency sounding. The UE 115 may transmit the partial SRS capability report via an uplink MAC-CE message, via a transmission associated with a power headroom (PHR) report of the UE 115, and/or the like.

At action 406, the BS 105 may transmit a partial SRS indication. In some aspects, the BS 105 may transmit the partial SRS indication using a DCI transmission. For instance, a field of the DCI transmission may be used to represent the partial SRS indication. By transmitting the partial SRS indication, the BS 105 may request that the UE 115 use only a subset of the configured SRS frequency resources available for use by the UE 115 at action 402. That is, for example, the BS 105 may request that the UE 115 sound over a partial set of the configured SRS frequency resources (e.g., a portion of the configured SRS frequency resources) . Sounding over the partial set of configured SRS frequency resources may involve the use of fewer SRS frequency resources, which may involve the use of fewer and/or the use of portions (e.g., a subset of available REs) of SRS resources (e.g., SRS resources 304) . To that end, the partial SRS indication may provide a reduction factor by which the UE 115 may reduce the number of SRS frequency resources used for transmission. For instance, a reduction factor of 2 may indicate to the UE 115to reduce the SRS frequency resources used for sounding by half (e.g., from 12 to 6 resources, 4 to 2 resources, and/or the like) . The partial SRS indication may additionally or alternatively provide a maximum number of SRS frequency resources the UE 115 may use for SRS transmission. In any case, the UE 115 may use the partial SRS indication to determine a number of SRS frequency resources to use for partial frequency sounding (e.g., to include in the partial set of the configured SRS frequency resources) . Further, by reducing the SRS frequency resources used by the UE 115, other wireless communication devices, such as other UEs, may be able to use remaining SRS frequency resources (e.g., the SRS frequency resources of the configured SRS frequency resources that are not included in the partial set of configured SRS frequency resources) . Thus, in some instances, another UE may use an SRS resource (e.g., SRS resource 304) or a portion thereof previously configured and allocated for use by the UE 115. Accordingly, the BS 105 may transmit the partial SRS indication to increase network capacity. Additionally or alternatively, the BS 105 may transmit the partial SRS indication in response to receiving the partial SRS capability report from the UE 115.

At action 408, based on the partial SRS indication, the UE 115 may transmit a second SRS over the partial set of the configured SRS frequency resources. In some aspects, the UE 115 may transmit the second SRS over the partial set of the configured SRS frequency resources using cyclic-shift, a “comb” structure, frequency-hopping, and/or the like. Further, the UE 115 may transmit the second SRS using a transmission power level (partial TxP) corresponding to partial frequency sounding. Accordingly, to transmit the second SRS, the UE 115 may be configured to determine the partial TxP. In some aspects, the UE 115 may determine the partial TxP in the manner described above with reference to action 404 and the full TxP. To that end, the UE 115 may determine the partial TxP based on the total number of SRS frequency resources included in the full set of the configured SRS frequency resources. Additionally or alternatively, the UE 115 may use the previously calculated full TxP as the partial TxP. Thus, the UE 115 may determine the partial TxP without performing a new calculation or a re-evaluation of transmission power level suitable for sounding. In particular, the UE 115 may be configured with one or more power control settings such that the UE 115 transmits any SRS using a transmission power level determined based on the number of SRS frequency resources included in the full set of the configured SRS frequency resources (e.g., full TxP) , regardless of whether the UE 115 is configured for partial frequency sounding.

Further, because the number of SRS frequency resources included in the partial set of the configured SRS frequency resources may be less than the number of SRS frequency resources included in the configured SRS frequency resources, transmitting the second SRS using a partial TxP determined based on the number of SRS frequency resources within the full set of the configured SRS frequency resources may result in a higher SNR associated with the second SRS than an SNR associated with the first SRS. As an illustrative example, if the half the number of SRS frequency resources are used to transmit the second SRS for partial frequency sounding as the number of SRS frequency resources used to transmit the first SRS for full frequency sounding, the SNR of the second SRS may be twice the SNR of the first SRS.

In some aspects, the UE 115 may determine the partial TxP based on the number of SRS frequency resources included in the partial set of the configured SRS frequency resources. For instance, the UE 115 may calculate the partial TxP using equation 1 (shown above) with the M _SRS term updated and/or redefined to reflect the number of SRS frequency resources (e.g., REs) in the partial set of the configured SRS frequency resources. That is, for example, the UE 115 may recompute a transmission power level using equation 1 and a new value of M _SRS. Alternatively, the UE 115 may calculate the partial TXP using a resource utilization parameter (e.g., a power backoff parameter) , along with equation 1 having the M _SRS term unchanged. In such cases, the utilization parameter may represent a ratio between the number of SRS frequency resources included in the partial set of the configured SRS frequency resources and the number of SRS frequency resources included in the full set of the configured SRS frequency resource. Thus, the UE 115 may calculate the utilization parameter by determining this ratio and/or based on the partial SRS indication. For instance, the UE 115 may determine the utilization parameter based on a reduction factor included in the partial SRS indication or its reciprocal. Further, the UE 115 may, in the calculation of the partial TxP with equation 1, modify (e.g., multiply) the term M _SRS and/or a result of the equation 1 by the utilization parameter.

By determining the partial TxP based on the number of SRS frequency resources within the partial set of the configured SRS frequency resources, the power (partial TxP) used to transmit the second SRS may be less than the power (full TxP) used to transmit the first SRS. As such, the power consumption at the UE 115 may be reduced. Moreover, transmitting the second SRS with a partial TxP determined based on the number of SRS frequency resources within the partial set of the configured SRS frequency resources may minimize interference at other UEs 115 or wireless communication devices within a network (e.g., network 100 of FIG. 1) . For instance, by transmitting the second SRS with the partial TxP determined based on the number of SRS frequency resources within the partial set of the configured SRS frequency resources, the power spectral density (PSD) associated with transmission of the second SRS may be lower than a PSD of an additional SRS transmitted over the partial set of the configured SRS frequency resources using full TxP (e.g., using transmission power level determined based on the number of SRS frequency resources within the full set of the configured SRS frequency resources) . Accordingly, the interference resulting from the transmission of the second SRS may be lower than the interference resulting from the transmission of the additional SRS.

In some aspects, the UE 115 may determine the partial TxP based on a power control mode associated with partial frequency sounding. The UE 115 may operate according to this power control mode in response to receiving the partial SRS indication (action 406) , for example. When operating according to the power control mode associated with partial frequency sounding, the UE 115 may use a fixed transmission power level for sounding (e.g., to transmit an SRS) . Thus, the UE 115 may determine the partial TxP based on the fixed transmission power level corresponding to the power control mode associated with partial frequency sounding. In this way, the UE 115 may determine the partial TxP without performing a calculation associated with the TxP, which may conserve power at the UE 115 and reduce implementation complexity.

In some aspects, the fixed transmission power level corresponding to the power control mode associated with partial frequency sounding may be semi-statically configured based on an RRC message, for example. Accordingly, the UE 115 may receive an indication of the fixed transmission power level from the BS 105 (e.g., at action 402) . Further, the fixed transmission power level may be any suitable power level, including a maximum transmission power level of the UE 115. Using a maximum transmission power level to perform partial frequency sounding may improve the SNR of the second SRS in comparison with an SRS transmitted with the full set of the configured SRS frequency resources, as similarly described above.

Moreover, in some aspects, the UE 115 may be configured to selectively use one or more of the techniques described herein to determine the partial TxP. For instance, the UE 115 may be configured to determine the partial TxP based on one of the number of SRS frequency resources in the full set of the configured SRS frequency resources, the number of SRS frequency resources in the partial set of the configured SRS frequency resources, or the power control mode associated with partial frequency sounding, in response to detecting a channel and/or network condition. Additionally or alternatively, the UE 115 may be configured to select a technique described herein to determine the partial TxP based on a message (e.g., a configuration message) received from the BS 105.

Further, after determining the partial TxP and transmitting the second SRS using the partial TxP, the UE 115 may be configured to continue transmitting subsequent SRSs using the partial set of the configured SRS frequency resources and the partial TxP unless and/or until the UE 115 is reconfigured or receives a suitable notification from the BS 105 to alter the transmission power level or the number of SRS frequency resources utilized for sounding by the UE 115. To that end, the UE 115 may remain configured for partial frequency sounding. Accordingly, the UE 115 may transmit subsequent SRS transmissions using the partial set of SRS frequency resources and the partial TxP without recalculating or re-evaluating the transmission power level for SRS transmission. Further, while a single SRS is illustrated as being transmitted by the UE at action 408, it may be appreciated that any number of SRSs may be transmitted using the partial TxP.

At action 410, the BS 105 may transmit a request for a power headroom (PHR) report. In some aspects, the BS 105 may transmit the request using a DCI transmission or any other suitable message to the UE 115. The PHR report may correspond to a transmit PHR at the UE 115. Further, the BS 105 may request the PHR report so that the BS 105 may determine scheduling information based on a received PHR report, for example.

At action 412, the UE 115 may transmit the requested PHR report to the BS 105. As illustrated, the UE 115 may transmit the PHR report via a medium access control (MAC) -control element (CE) message (e.g., an uplink MAC-CE message) . Moreover, before transmission of the PHR report to the BS 105, the UE 115 may determine the PHR. According to some aspects, the determination of the PHR may depend on whether the UE 115 is configured to perform full or partial frequency sounding (e.g., whether the UE 115 transmits an SRS using a full or partial set of the configured SRS frequency resources) . For instance, if the UE 115 is configured to perform full frequency sounding, the UE may calculate the PHR as shown below:

where P _CMAX represents the maximum transmit power configured for the UE 115, for example, according to a particular communication standard.

represents the power to transmit an SRS using the configured SRS frequency resources, which may correspond to the full TxP described herein. In such cases, the PHR indicates the remaining transmission power level available (e.g., a transmission power headroom) for the UE 115 to use.

If, on the other hand, the UE 115 is configured to perform partial frequency sounding, the UE 115 may calculate the PHR as shown below:

where

represents the power to transmit an SRS using the configured SRS frequency resources, which may correspond to a maximum sounding power (e.g., full TxP) , and

represents the power to transmit an SRS using the partial set of the configured SRS frequency resources, which may correspond to the partial TxP described herein. In such cases, the PHR indicates the difference between the maximum sounding power and the partial TxP (e.g., an actual transmission power level used by the UE 115) . Yet, an additional difference, or delta, in transmission power level may exist between the maximum transmit power level (P _CMAX) of the UE 115 and the maximum sounding power level

Thus, a PHR determined based on full SRS sounding may signify a headroom value with respect to a maximum device transmit power (P _CMAX) and a full frequency sounding power

while a PHR determined based on partial SRS sounding may signify a headroom value with respect to partial and full frequency sounding powers. Accordingly, to ensure the BS 105 is able to distinguish whether a particular PHR report received from the UE 115 corresponds to a PHR associated with full or partial frequency sounding, the UE 115 may transmit the PHR report with an indication of the sounding configuration (e.g., full or partial) . For instance, the UE 115 may include a flag within the PHR report and/or within a message used to transmit the PHR report, such as the MAC-CE, that is indicative of the sounding configuration. As an illustrative example, the flag may be set to a first state (e.g., logical high) when the UE 115 is configured to operate according to full frequency sounding, and the flag may be set to a second state (e.g., logical low) when the UE 115 is configured to operate according to partial frequency sounding or vice versa. Moreover, the UE 115 may provide the indication of the sounding configuration via the partial SRS capability report. For instance, in some embodiments, the UE 115 may be configured to transmit the partial SRS capability report when the UE 115 is configured to operate with partial frequency sounding and/or in association with the PHR report.

Additionally or alternatively, the UE 115 may be configured to transmit an indication of the delta between the maximum transmit power (P _CMAX) and the maximum sounding power

within the PHR report and/or the message used to transmit the PHR report. For instance, the UE 115 may transmit the value of the delta, an additional PHR, an index mapping to the value of the delta in a look-up-table, and/or the like. In this way, the BS 105 may be able to determine both the headroom between the partial and full frequency sounding power, as well as the overall headroom between the partial frequency sounding power and the maximum transmit power, based on the information associated with the PHR report transmitted by the UE 115 when the UE 115 is configured to operate with partial frequency sounding.

In some aspects, the UE 115 may transmit the indication of the delta when operating with partial frequency sounding and may not transmit an indication of the delta when operating with full frequency sounding. In such cases, the UE 115 may transmit the indication of the delta along with the indication of the sounding configuration being a partial frequency sounding configuration (e.g., the flag set to the second state) . Further, in some aspects, the UE 115 may be configured to transmit the indication of the delta while configured for full or partial frequency sounding. In such cases, the UE 115 may be configured to indicate that the delta is zero when the UE 115 is configured for full frequency sounding and may be configured to indicate the value of delta, which may be zero or non-zero, when the UE 115 is configured for partial frequency sounding. Moreover, because the value of the delta is zero when the UE 115 is configured for full frequency sounding and may be non-zero for partial frequency sounding, the indication of the delta may be used as or in place of the indication of the sounding configuration.

While aspects of FIG. 4 and the method 400 are described herein at the granularity of SRS frequency resources, which may correspond to REs 212 of FIG. 2, it may be appreciated that the method 400 may additionally or alternatively be used at the granularity of SRS resources 304, which may include one or more SRS frequency resources (e.g., one or more REs 212 and/or RBs 210) . For instance, the partial TxP may be determined based on the number of SRS resources 304 within a SRS resource set 302 and/or the number of SRS resources 304 within a subset of the SRS resource set 302 used to transmit an SRS. To that end, aspects are intended to be exemplary and not limiting.

FIG. 5 is a block diagram of an exemplary UE 500 according to some aspects of the present disclosure. The UE 500 may be a UE 115 in the network 100 as discussed above in FIG. 1. As shown, the UE 500 may include a processor 502, a processor 502, an SRS module 508, a transceiver 510 including a modem subsystem 512 and a RF unit 514, and one or more antennas 516. These elements may be in direct or indirect communication with each other, for example via one or more buses.

The processor 502 may have various features as a specific-type processor. For example, these may include a CPU, a DSP, an ASIC, a controller, a FPGA device, another hardware device, a firmware device, or any combination thereof configured to perform the operations described herein. The processor 502 may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

The processor 502 may include a cache memory (e.g., a cache memory of the processor 502) , RAM, MRAM, ROM, PROM, EPROM, EEPROM, flash memory, a solid state memory device, one or more hard disk drives, memristor-based arrays, other forms of volatile and non-volatile memory, or a combination of different types of memory. In some aspects, the processor 502 may include a non-transitory computer-readable medium. The processor 502 may store instructions 506. The instructions 506 may include instructions that, when executed by the processor 502, cause the processor 502 to perform operations described herein, for example, aspects of FIGS. 1-4 and 7. Instructions 506 may also be referred to as program code. The program code may be for causing a wireless communication device to perform these operations, for example by causing one or more processors (such as processor 502) to control or command the wireless communication device to do so. The terms “instructions” and “code” should be interpreted broadly to include any type of computer-readable statement (s) . For example, the terms “instructions” and “code” may refer to one or more programs, routines, sub-routines, functions, procedures, etc. “Instructions” and “code” may include a single computer-readable statement or many computer-readable statements.

The SRS module 508 may be implemented via hardware, software, or combinations thereof. For example, the SRS module 508 may be implemented as a processor, circuit, and/or instructions 506 stored in the processor 502 and executed by the processor 502. In some examples, the SRS module 508 can be integrated within the modem subsystem 512. For example, the SRS module 508 can be implemented by a combination of software components (e.g., executed by a DSP or a general processor) and hardware components (e.g., logic gates and circuitry) within the modem subsystem 512.

The SRS module 508 may be used for various aspects of the present disclosure, for example, aspects of FIGS. 4 and 7. For example, the SRS module 508 may be configured to receive an SRS resource configuration (e.g., via an RRC message) from a BS (e.g., the BSs 105 and/or 600) to which the UE 500 is attached. The SRS module 508 may be configured to determine a transmission power level for transmitting a first SRS, using full frequency sounding, based on a number of SRS frequency resources included in the full set of the configured SRS frequency resources indicated by the received SRS resource configuration. Further, after receiving a partial SRS indication from the BS, the SRS module 508 may be configured to determine a transmission power level for transmitting a second SRS, using partial frequency sounding, based on a number of SRS frequency resources included in a partial set of the configured SRS resources determined based on the partial SRS indication. In some aspects, the SRS module 508 may be configured to transmit a PHR report identifying an associated PHR as corresponding to full frequency sounding or partial frequency sounding to the BS.

As shown, the transceiver 510 may include the modem subsystem 512 and the RF unit 514. The transceiver 510 can be configured to communicate bi-directionally with other devices, such as the UEs 115 and/or another core network element. The modem subsystem 512 may be configured to modulate and/or encode data according to a MCS, e.g., a LDPC coding scheme, a turbo coding scheme, a convolutional coding scheme, a digital beamforming scheme, etc. The RF unit 514 may be configured to process (e.g., perform analog to digital conversion or digital to analog conversion, etc. ) modulated/encoded data (e.g., PDSCH signal, PDCCH signal, SRS resource configuration, SRS resource activation, SRS resource deactivation) from the modem subsystem 512 (on outbound transmissions) or of transmissions originating from another source such as a UE 115. The RF unit 514 may be further configured to perform analog beamforming in conjunction with the digital beamforming. Although shown as integrated together in transceiver 510, the modem subsystem 512 and/or the RF unit 514 may be separate devices that are coupled together at the UE 500 to enable the UE 500 to communicate with other devices.

The RF unit 514 may provide modulated and/or processed data, e.g. data packets (or, more generally, data messages that may contain one or more data packets and other information) , to the antennas 516 for transmission to one or more other devices. This may include, for example, transmission of information to complete attachment to a network and communication with a camped UE 115 according to some aspects of the present disclosure. The antennas 516 may further receive data messages transmitted from other devices and provide the received data messages for processing and/or demodulation at the transceiver 510. The transceiver 510 may provide the demodulated and decoded data (e.g., PUSCH signal, UL data, SRSs, UE capability reports, RI reports) to the SRS module 508 for processing. The antennas 516 may include multiple antennas of similar or different designs to sustain multiple transmission links.

In an aspect, the UE 500 can include multiple transceivers 510 implementing different RATs (e.g., NR and LTE) . In an aspect, the UE 500 can include a single transceiver 510 implementing multiple RATs (e.g., NR and LTE) . In an aspect, the transceiver 510 can include various components, where different combinations of components can implement different RATs.

FIG. 6 is a block diagram of an exemplary BS 600 according to some aspects of the present disclosure. The BS 600 may be a BS 105 discussed above in FIG. 1. As shown, the BS 600 may include a processor 602, a memory 604, a SRS resource allocation module 608, a transceiver 610 including a modem subsystem 612 and a radio frequency (RF) unit 614, and one or more antennas 616. These elements may be in direct or indirect communication with each other, for example via one or more buses.

The processor 602 may include a central processing unit (CPU) , a digital signal processor (DSP) , an application specific integrated circuit (ASIC) , a controller, a field programmable gate array (FPGA) device, another hardware device, a firmware device, or any combination thereof configured to perform the operations described herein. The processor 602 may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

The memory 604 may include a cache memory (e.g., a cache memory of the processor 602) , random access memory (RAM) , magnetoresistive RAM (MRAM) , read-only memory (ROM) , programmable read-only memory (PROM) , erasable programmable read only memory (EPROM) , electrically erasable programmable read only memory (EEPROM) , flash memory, solid state memory device, hard disk drives, other forms of volatile and non-volatile memory, or a combination of different types of memory. In an aspect, the memory 604 includes a non-transitory computer-readable medium. The memory 604 may store, or have recorded thereon, instructions 606. The instructions 606 may include instructions that, when executed by the processor 602, cause the processor 602 to perform the operations described herein with reference to the BSs 105 in connection with aspects of the present disclosure, for example, aspects of FIGS. 1-4 and 8. Instructions 606 may also be referred to as program code, which may be interpreted broadly to include any type of computer-readable statement (s) as discussed above with respect to FIG. 5.

The SRS resource allocation module 608 may be implemented via hardware, software, or combinations thereof. For example the SRS resource allocation module 608 may be implemented as a processor, circuit, and/or instructions 606 stored in the memory 604 and executed by the processor 602. In some examples, the SRS resource allocation module 608 can be integrated within the modem subsystem 612. For example, the SRS resource allocation module 608 can be implemented by a combination of software components (e.g., executed by a DSP or a general processor) and hardware components (e.g., logic gates and circuitry) within the modem subsystem 612.

The SRS resource allocation module 608 may be used for various aspects of the present disclosure, for example, aspects of FIGS. 1-4 and 8. The SRS resource allocation module 608 may be configured to configure and allocate SRS resources to a UE (e.g., UE 115, 500) . That is, for example, the SRS resource allocation module 608 may determine an SRS resource configuration that the BS 600 may transmit to the UE. The SRS resource allocation module 608 may additionally generate or determine a partial SRS indication configured to request the UE to sound over a partial set of SRS frequency resources. Further, the SRS resource allocation module 608 may determine a PHR report request to transmit to the UE and may receive a PHR report transmitted from the UE in response. In some aspects, the SRS resource allocation module 608 may determine resource allocation and/or scheduling, such as SRS resource allocation, based on the received PHR report.

As shown, the transceiver 610 may include a modem subsystem 612 and an RF unit 614. The transceiver 610 can be configured to communicate bi-directionally with other devices, such as the BSs 105. The modem subsystem 612 may be configured to modulate and/or encode the data from the memory 604 according to a modulation and coding scheme (MCS) , e.g., a low-density parity check (LDPC) coding scheme, a turbo coding scheme, a convolutional coding scheme, a digital beamforming scheme, etc. The RF unit 614 may be configured to process (e.g., perform analog to digital conversion or digital to analog conversion, etc. ) modulated/encoded data (e.g., PUSCH signal, UL data, SRSs, UE capability reports, RI reports) from the modem subsystem 612 (on outbound transmissions) or of transmissions originating from another source such as a UE 115 or a BS 105. The RF unit 614 may be further configured to perform analog beamforming in conjunction with the digital beamforming. Although shown as integrated together in transceiver 610, the modem subsystem 612 and the RF unit 614 may be separate devices that are coupled together at the BS 600 to enable the BS 600 to communicate with other devices.

The RF unit 614 may provide modulated and/or processed data, e.g. data packets (or, more generally, data messages that may contain one or more data packets and other information) , to the antennas 616 for transmission to one or more other devices. The antennas 616 may further receive data messages transmitted from other devices. The antennas 616 may provide the received data messages for processing and/or demodulation at the transceiver 610. The transceiver 610 may provide the demodulated and decoded data (e.g., PDSCH signal, PDCCH, DL data, SRS resource configuration, SRS resource activation, SRS resource deactivation) to the SRS resource allocation module 608. The antennas 616 may include multiple antennas of similar or different designs in order to sustain multiple transmission links. The RF unit 614 may configure the antennas 616.

In an aspect, the BS 600 can include multiple transceivers 610 implementing different RATs (e.g., NR and LTE) . In an aspect, the BS 600 can include a single transceiver 610 implementing multiple RATs (e.g., NR and LTE) . In an aspect, the transceiver 610 can include various components, where different combinations of components can implement different RATs.

FIG. 7 is a flow diagram of a wireless communication method 700, according to some aspects of the present disclosure. Aspects of the method 700 can be executed by a computing device (e.g., a processor, processing circuit, and/or other suitable component) of a wireless communication device or other suitable means for performing the steps. For example, a wireless communication device, such as the UEs 115 and/or 500 may utilize one or more components, such as the processor 502, the memory 504, the SRS module 508, the transceiver 510, the modem 512, and the one or more antennas 516, to execute the steps of method 700. As illustrated, the method 700 includes a number of enumerated steps, but aspects of the method 700 may include additional steps before, after, and in between the enumerated steps. In some aspects, one or more of the enumerated steps may be omitted or performed in a different order.

At block 710, a UE (e.g., the UEs 115 and/or 500) can receive, from a BS (e.g., BS 105 and/or BS 600) , an indication to use a portion of configured of SRS frequency resources for transmitting an SRS to the BS. For instance, the indication may correspond to the partial SRS indication described above with reference to FIG. 4 (action 406) . Further, in some aspects, the UE may receive the indication by receiving an RRC message including the indication.

At block 720, the UE may determine, in response to receiving the indication, a first SRS transmission power level for transmitting the SRS to the BS using the portion of the configured SRS frequency resources. For instance, the UE may determine the partial transmission power level (partial TxP) to transmit the second SRS over the partial set of the configured SRS frequency resources, as described above with reference to action 408 of FIG. 4.

In some aspects of the method 700, the UE may determine the first SRS transmission power level by computing a second SRS transmission power level for transmitting the SRS using the configured SRS frequency resources. For instance, determining the first SRS transmission power level, which may correspond to a partial TxP, may involve computing the second SRS transmission power level, which may correspond to a full TxP. To that end, the UE may determine the first SRS transmission power level using equation 1, as shown above. Moreover, in some aspects, the method 700 may further involve the UE transmitting, to the BS, the SRS with the second SRS transmission power level using the portion of the configured SRS frequency resources. That is, for example, the UE may transmit the SRS using the full TxP and a partial set of the configured SRS frequency resources.

In some aspects of the method 700, the UE may transmit, to the BS, the SRS using a number of SRS frequency resources included in the portion of the configured SRS frequency resources. Further, in such aspects, the UE may determine the first SRS transmission power level by computing the first SRS transmission power level for transmitting the SRS using the number of SRS frequency resources included in the configured SRS frequency resources and a resource utilization parameter. For instance, the UE may determine the first SRS transmission power level using equation 1 and an M _SRS term that is updated or modified (e.g., by a resource utilization parameter) to reflect the number of SRS frequency resources within the portion of the configured SRS frequency resources.

In some aspects of the method 700, the first SRS transmission power level is semi-statically configured by the BS. For instance, the first SRS transmission power level may be semi-statically configured based on an RRC message received at the UE from the BS. In some aspects, the first SRS transmission power level may be a maximum transmission power level of the UE. The semi-static configuration and/or the maximum transmission power level value of the first SRS transmission power level may correspond to a power control mode associated with partial frequency sounding, for example.

In some aspects of the method 700, the UE may transmit, to the BS, a PHR report including a flag indicating the using by the UE of the portion of the configured SRS frequency resources to transmit the SRS to the BS. For example, the UE may indicate in the PHR report that the PHR corresponds to partial frequency sounding. Further, in some aspects, the UE may transmit, to the BS, a PHR report that includes a difference between the first SRS transmission power level and a second SRS transmission power level for transmitting the SRS using the configured SRS frequency resources. The difference may correspond to a difference between the partial TxP and the full TxP, for example. In some aspects, the UE may transmit the PHR report as or within a MAC-CE message, as illustrated in FIG. 4 (action 412) .

In some aspects of the method 700, the UE may transmit, to the BS, an indication of a capability, by the UE, to transmit SRSs using the portion of the configured SRS frequency resources. For instance, as described with reference to action 405 of FIG. 4, the UE may transmit a partial SRS capability report, which indicates that the UE is capable of performing partial frequency sounding.

FIG. 8 is a flow diagram of a wireless communication method 800, according to some aspects of the present disclosure. Aspects of the method 800 can be executed by a computing device (e.g., a processor, processing circuit, and/or other suitable component) of a wireless communication device or other suitable means for performing the steps. For example, a wireless communication device, such as the BSs 105 and/or 600 may utilize one or more components, such as the processor 602, the memory 604, the SRS resource allocation module 608, the transceiver 610, the modem 612, and the one or more antennas 616, to execute the steps of method 800. As illustrated, the method 800 includes a number of enumerated steps, but aspects of the method 800 may include additional steps before, after, and in between the enumerated steps. In some aspects, one or more of the enumerated steps may be omitted or performed in a different order.

At block 810, a BS (e.g., the BSs 105 and/or 600) can transmit, to a UE (e.g., UEs 115 and/or 500) , an indication to use a portion of configured of SRS frequency resources for transmitting an SRS to the BS. For instance, the indication may correspond to the partial SRS indication described above with reference to FIG. 4 (action 406) . Further, in some aspects, the BS may transmit the indication via an RRC message including the indication.

At block 820, the BS may receive, from the UE using the portion of the configured SRS frequency resources, the SRS at a first SRS transmission power level. For instance, the BS may receive the SRS over the partial set of the configured SRS frequency resources at the partial transmission power level (partial TxP) , as described above with reference to action 408 of FIG. 4.

In some aspects of the method 800, the BS may receive, from the UE, an indication of a capability to transmit SRSs using the portion of the configured SRS frequency resources. For instance, the BS may receive the partial SRS capability report (e.g., action 405 of FIG. 4) , which indicates that the UE can perform partial frequency sounding. Further, in such aspects, the BS may transmit the indication to use the portion of the configured SRS frequency resources based on the indication of the capability. That is, for example, the BS may transmit the partial SRS indication (e.g., at action 406 of FIG. 4) in response to receiving the partial SRS capability report.

In some aspects of the method 800, the BS may transmit, to the UE, an indication to use the configured SRS frequency resources for transmitting a second SRS. For example, the BS may transmit the SRS resource configuration (e.g., via an RRC message) to configure and allocate the configured SRS frequency resources to the UE for transmitting an SRS, as described with reference to action 402 of FIG. 4. In such aspects, the BS may further receive, from the UE using the configured SRS frequency resources, the second SRS at a second SRS transmission power level. For instance, the BS may receive the SRS transmitted at full TxP (e.g., at action 404 of FIG. 4) . Moreover, in some aspects of the method 800, the second SRS transmission power level is the same as the first SRS transmission power level, and in some aspects, the first and second SRS power transmission levels are different. To that end, the partial TxP may be the same as or different from the full TxP, as described herein. Further, in some aspects, the BS may semi-statically configure the first transmission power level (e.g., via an RRC message) , and in some aspects, the first transmission power level is a maximum transmission power level of the UE.

In some aspects of the method 800, the BS may transmit, to the UE, a request for a power headroom (PHR) report, and the BS may receive, from the UE, the PHR report. The PHR report may be a MAC-CE message. Moreover, in some aspects, the PHR report may include a flag indicating the UE using the portion of the configured SRS frequency resources. In particular, the PHR report may indicate that the UE is configured to operate according to partial frequency sounding. Further, in some aspects, the PHR report includes a difference between the first SRS transmission power level and a second SRS transmission power level for transmitting, from the UE, a second SRS using the configured SRS frequency resources. For instance, the PHR report may include the difference between partial TxP and full TxP.

Information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

The various illustrative blocks and modules described in connection with the disclosure herein may be implemented or performed with a general-purpose processor, a DSP, an ASIC, an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration) .

The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Other examples and implementations are within the scope of the disclosure and appended claims. For example, due to the nature of software, functions described above can be implemented using software executed by a processor, hardware, firmware, hardwiring, or combinations of any of these. Features implementing functions may also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations. Also, as used herein, including in the claims, “or” as used in a list of items (for example, a list of items prefaced by a phrase such as “at least one of” or “one or more of” ) indicates an inclusive list such that, for example, a list of [at least one of A, B, or C] means A or B or C or AB or AC or BC or ABC (i.e., A and B and C) .

As those of some skill in this art will by now appreciate and depending on the particular application at hand, many modifications, substitutions and variations can be made in and to the materials, apparatus, configurations and methods of use of the devices of the present disclosure without departing from the spirit and scope thereof. In light of this, the scope of the present disclosure should not be limited to that of the particular embodiments illustrated and described herein, as they are merely by way of some examples thereof, but rather, should be fully commensurate with that of the claims appended hereafter and their functional equivalents.

Claims

A method of wireless communication performed by a user equipment (UE) , the method comprising:

receiving, from a base station (BS) , an indication to use a portion of configured sounding reference signal (SRS) frequency resources for transmitting an SRS from the UE to the BS; and

determining, in response to the receiving the indication, a first SRS transmission power level for transmitting the SRS from the UE to the BS using the portion of the configured SRS frequency resources.
The method of claim 1, wherein the determining the first SRS transmission power level includes computing a second SRS transmission power level for transmitting the SRS using each of the configured SRS frequency resources.
The method of claim 2, further comprising:

transmitting, to the BS, the SRS with the second SRS transmission power level using the portion of the configured SRS frequency resources.
The method of claim 1, wherein the determining the first SRS transmission power level includes computing the first SRS transmission power level based on a number of SRS frequency resources included in the portion of the configured SRS frequency resources.
The method of claim 4, wherein the determining the first SRS transmission power level further includes computing the first SRS transmission power level based on a number of SRS frequency resources included in the configured SRS frequency resources and a resource utilization parameter.
The method of claim 1, further comprising:

transmitting, to the BS with the first SRS transmission power level, the SRS using the portion of the configured SRS frequency resources.
The method of claim 1, wherein the first SRS transmission power level is semi-statically configured by the BS.
The method of claim 1, wherein the first SRS transmission power level is a maximum transmission power level of the UE.
The method of claim 1, wherein the receiving the indication includes receiving a radio resource control (RRC) message including the indication.
The method of claim 1, further comprising:

transmitting, to the BS, a power headroom (PHR) report including a flag indicating the using by the UE of the portion of the configured SRS frequency resources to transmit the SRS to the BS.
The method of claim 1, further comprising:

transmitting, to the BS, a PHR report including a difference between the first SRS transmission power level and a second SRS transmission power level for transmitting the SRS using the configured SRS frequency resources.
The method of claim 10 or 11, wherein the PHR report is a medium access control (MAC) -control element (CE) message.
The method of claim 1, further comprising transmitting, to the BS, an indication of a capability, by the UE, to transmit SRSs using the portion of the configured SRS frequency resources.
A method of wireless communication performed by a base station (BS) , the method comprising:

transmitting, to a user equipment (UE) , an indication to use a portion of configured sounding reference signal (SRS) frequency resources for transmitting an SRS from the UE to the BS; and

receiving, from the UE using the portion of the configured SRS frequency resources, the SRS at a first SRS transmission power level.
The method of claim 14, further comprising:

receiving, from the UE, an indication of a capability to transmit SRSs using the portion of the configured SRS frequency resources; and

transmitting the indication to use the portion of the configured SRS frequency resources based on the indication of the capability.
The method of claim 14, further comprising:

transmitting, to the UE, an indication to use the configured SRS frequency resources for transmitting a second SRS; and

receiving, from the UE using the configured SRS frequency resources, the second SRS at a second SRS transmission power level.
The method of claim 16, wherein the first SRS transmission power level is the same as the second SRS transmission power level.
The method of claim 16, wherein the first SRS transmission power level is different from the second SRS transmission power level.
The method of claim 14, further comprising:

transmitting, to the UE, a request for a power headroom (PHR) report; and

receiving, from the UE, the PHR report.
The method of claim 19, the PHR report including a flag indicating the UE using the portion of the configured SRS frequency resources.
The method of claim 19, the PHR report including a difference between the first SRS transmission power level and a second SRS transmission power level for transmitting, from the UE, a second SRS using the configured SRS frequency resources.
The method of claim 19, wherein PHR report is a medium access control (MAC) -control element (CE) message.
The method of claim 14, further comprising, semi-statically configuring the first SRS transmission power level.
The method of claim 14, wherein the first SRS transmission power level is a maximum transmission power level of the UE.
The method of claim 14, wherein the transmitting the indication includes transmitting a radio resource control (RRC) message including the indication.
A user equipment (UE) , comprising:

a transceiver configured to receive, from a base station (BS) , an indication to use a portion of configured sounding reference signal (SRS) frequency resources for transmitting an SRS from the UE to the BS; and

a processor configured to determine, in response to the receiving the indication, a first SRS transmission power level for transmitting the SRS from the UE to the BS using the portion of the configured SRS frequency resources.
The UE of claim 26, wherein the processor configured to determine the first SRS transmission power level is configured to:

compute a second SRS transmission power level for transmitting the SRS using each of the configured SRS frequency resources.
The UE of claim 27, wherein the transceiver is configured to:

transmit, to the BS, the SRS with the second SRS transmission power level using the portion of the configured SRS frequency resources.
The UE of claim 26, wherein the processor configured to determine the first SRS transmission power level is configured to:

compute the first SRS transmission power level based on a number of SRS frequency resources included in the portion of the configured SRS frequency resources.
The UE of claim 29, wherein the processor configured to determine the first SRS transmission power level is further configured to:

compute the first SRS transmission power level based on a number of SRS frequency resources included in the configured SRS frequency resources and a resource utilization parameter.
The UE of claim 26, wherein the transceiver is configured to:

transmit, to the BS with the first SRS transmission power level, the SRS using the portion of the configured SRS frequency resources.
The UE of claim 26, wherein the first SRS transmission power level is semi-statically configured by the BS.
The UE of claim 26, wherein the first SRS transmission power level is a maximum transmission power level of the UE.
The UE of claim 26, wherein the transceiver is configured to:

receive the indication by receiving a radio resource control (RRC) message including the indication.
The UE of claim 26, wherein the transceiver is further configured to:

transmit, to the BS, a power headroom (PHR) report including a flag indicating the using by the UE of the portion of the configured SRS frequency resources to transmit the SRS to the BS.
The UE of claim 26, wherein the transceiver is further configured to:

transmit, to the BS, a PHR report including a difference between the first SRS transmission power level and a second SRS transmission power level for transmitting the SRS using the configured SRS frequency resources.
The UE of claim 35 or 36, wherein the PHR report is a medium access control (MAC) -control element (CE) message.
The UE of claim 26, wherein the transceiver is further configured to:

transmit, to the BS, an indication of a capability, by the UE, to transmit SRSs using the portion of the configured SRS frequency resources.
A base station (BS) , comprising:

a processor; and

a transceiver configured to:

transmit, to a user equipment (UE) , an indication to use a portion of configured sounding reference signal (SRS) frequency resources for transmitting an SRS from the UE to the BS; and

receive, from the UE using the portion of the configured SRS frequency resources, the SRS at a first SRS transmission power level.
The BS of claim 39, wherein the transceiver is further configured to:

receive, from the UE, an indication of a capability to transmit SRSs using the portion of the configured SRS frequency resources; and

transmit the indication to use the portion of the configured SRS frequency resources based on the indication of the capability.
The BS of claim 39, wherein the transceiver is further configured to:

transmit, to the UE, an indication to use the configured SRS frequency resources for transmitting a second SRS; and

receive, from the UE using the configured SRS frequency resources, the second SRS at a second SRS transmission power level.
The BS of claim 41, wherein the first SRS transmission power level is the same as the second SRS transmission power level.
The BS of claim 41, wherein the first SRS transmission power level is different from the second SRS transmission power level.
The BS of claim 39, wherein the transceiver is further configured to:

transmit, to the UE, a request for a power headroom (PHR) report; and

receive, from the UE, the PHR report.
The BS of claim 44, the PHR report including a flag indicating the UE using the portion of the configured SRS frequency resources.
The BS of claim 44, the PHR report including a difference between the first SRS transmission power level and a second SRS transmission power level for transmitting, from the UE, a second SRS using the configured SRS frequency resources.
The BS of claim 44, wherein PHR report is a medium access control (MAC) -control element (CE) message.
The BS of claim 39, wherein the processor is configured to semi-statically configure the first SRS transmission power level.
The BS of claim 39, wherein the first SRS transmission power level is a maximum transmission power level of the UE.
The BS of claim 39, wherein the transceiver configured to transmit the indication is further configured to transmit a radio resource control (RRC) message including the indication.
A non-transitory computer-readable medium having program code recorded thereon, the program code comprising:

code for causing a user equipment (UE) to receive, from a base station (BS) , an indication to use a portion of configured sounding reference signal (SRS) frequency resources for transmitting an SRS from the UE to the BS; and

code for causing the UE to determine, in response to the receiving the indication, a first SRS transmission power level for transmitting the SRS from the UE to the BS using the portion of the configured SRS frequency resources.
The non-transitory computer-readable medium of claim 51, wherein the code for causing the UE to determine the first SRS transmission power level is further configured to:

compute a second SRS transmission power level for transmitting the SRS using each of the configured SRS frequency resources.
The non-transitory computer-readable medium of claim 52, further comprising code for causing the UE to:

transmit, to the BS, the SRS with the second SRS transmission power level using the portion of the configured SRS frequency resources.
The non-transitory computer-readable medium of claim 51, wherein the code for causing the UE to determine the first SRS transmission power level is further configured to:

compute the first SRS transmission power level based on a number of SRS frequency resources included in the portion of the configured SRS frequency resources.
The non-transitory computer-readable medium of claim 54, wherein the code for causing the UE to determine the first SRS transmission power level is further configured to:

compute the first SRS transmission power level based on a number of SRS frequency resources included in the configured SRS frequency resources and a resource utilization parameter.
The non-transitory computer-readable medium of claim 51, further comprising code for causing the UE to:

transmit, to the BS with the first SRS transmission power level, the SRS using the portion of the configured SRS frequency resources.
The non-transitory computer-readable medium of claim 51, wherein the first SRS transmission power level is semi-statically configured by the BS.
The non-transitory computer-readable medium of claim 51, wherein the first SRS transmission power level is a maximum transmission power level of the UE.
The non-transitory computer-readable medium of claim 51, wherein the code for causing the UE to receive the indication is further configured to:

receive the indication by receiving a radio resource control (RRC) message including the indication.
The non-transitory computer-readable medium of claim 51, further comprising code for causing the UE to:

transmit, to the BS, a power headroom (PHR) report including a flag indicating the using by the UE of the portion of the configured SRS frequency resources to transmit the SRS to the BS.
The non-transitory computer-readable medium of claim 51, further comprising code for causing the UE to:

transmit, to the BS, a PHR report including a difference between the first SRS transmission power level and a second SRS transmission power level for transmitting the SRS using the configured SRS frequency resources.
The non-transitory computer-readable medium of claim 60 or 61, wherein the PHR report is a medium access control (MAC) -control element (CE) message.
The non-transitory computer-readable medium of claim 51, further comprising code for causing the UE to:

transmit, to the BS, an indication of a capability, by the UE, to transmit SRSs using the portion of the configured SRS frequency resources.
A non-transitory computer-readable medium having program code recorded thereon, the program code comprising:

code for causing a base station (BS) to transmit, to a user equipment (UE) , an indication to use a portion of configured sounding reference signal (SRS) frequency resources for transmitting an SRS from the UE to the BS; and

code for causing the BS to receive, from the UE using the portion of the configured SRS frequency resources, the SRS at a first SRS transmission power level.
The non-transitory computer-readable medium of claim 64, further comprising code for causing the BS to:

receive, from the UE, an indication of a capability to transmit SRSs using the portion of the configured SRS frequency resources; and

transmit the indication to use the portion of the configured SRS frequency resources based on the indication of the capability.
The non-transitory computer-readable medium of claim 64, further comprising code for causing the BS to:

transmit, to the UE, an indication to use the configured SRS frequency resources for transmitting a second SRS; and

receive, from the UE using the configured SRS frequency resources, the second SRS at a second SRS transmission power level.
The non-transitory computer-readable medium of claim 66, wherein the first SRS transmission power level is the same as the second SRS transmission power level.
The non-transitory computer-readable medium of claim 66, wherein the first SRS transmission power level is different from the second SRS transmission power level.
The non-transitory computer-readable medium of claim 64, further comprising code for causing the BS to:

transmit, to the UE, a request for a power headroom (PHR) report; and

receive, from the UE, the PHR report.
The non-transitory computer-readable medium of claim 69, the PHR report including a flag indicating the UE using the portion of the configured SRS frequency resources.
The non-transitory computer-readable medium of claim 69, the PHR report including a difference between the first SRS transmission power level and a second SRS transmission power level for transmitting, from the UE, a second SRS using the configured SRS frequency resources.
The non-transitory computer-readable medium of claim 69, wherein PHR report is a medium access control (MAC) -control element (CE) message.
The non-transitory computer-readable medium of claim 64, further comprising code for causing the BS to semi-statically configure the first SRS transmission power level.
The non-transitory computer-readable medium of claim 64, wherein the first SRS transmission power level is a maximum transmission power level of the UE.
The non-transitory computer-readable medium of claim 64, wherein the code for causing the BS to transmit the indication is further configured to transmit a radio resource control (RRC) message including the indication.
A user equipment (UE) , comprising:

means for receiving, from a base station (BS) , an indication to use a portion of configured sounding reference signal (SRS) frequency resources for transmitting an SRS from the UE to the BS; and

means for determining, in response to the receiving the indication, a first SRS transmission power level for transmitting the SRS from the UE to the BS using the portion of the configured SRS frequency resources.
The UE of claim 76, wherein the means for determining the first SRS transmission power level is further configured to:

compute a second SRS transmission power level for transmitting the SRS using each of the configured SRS frequency resources.
The UE of claim 77, further comprising means for transmitting, to the BS, the SRS with the second SRS transmission power level using the portion of the configured SRS frequency resources.
The UE of claim 76, wherein the means for determining the first SRS transmission power level is further configured to:

compute the first SRS transmission power level based on a number of SRS frequency resources included in the portion of the configured SRS frequency resources.
The UE of claim 79, wherein the means for determining the first SRS transmission power level is further configured to:

compute the first SRS transmission power level based on a number of SRS frequency resources included in the configured SRS frequency resources and a resource utilization parameter.
The UE of claim 76, further comprising means for transmitting, to the BS with the first SRS transmission power level, the SRS using the portion of the configured SRS frequency resources.
The UE of claim 76, wherein the first SRS transmission power level is semi-statically configured by the BS.
The UE of claim 76, wherein the first SRS transmission power level is a maximum transmission power level of the UE.
The UE of claim 76, wherein the means for receiving the indication is further configured to:

receive the indication by receiving a radio resource control (RRC) message including the indication.
The UE of claim 76, further comprising means for transmitting, to the BS, a power headroom (PHR) report including a flag indicating the using by the UE of the portion of the configured SRS frequency resources to transmit the SRS to the BS.
The UE of claim 76, further comprising means for transmitting, to the BS, a PHR report including a difference between the first SRS transmission power level and a second SRS transmission power level for transmitting the SRS using the configured SRS frequency resources.
The UE of claim 85 or 86, wherein the PHR report is a medium access control (MAC) -control element (CE) message.
The UE of claim 76, further comprising means for transmitting, to the BS, an indication of a capability, by the UE, to transmit SRSs using the portion of the configured SRS frequency resources.
A base station (BS) , comprising:

means for transmitting, to a user equipment (UE) , an indication to use a portion of configured sounding reference signal (SRS) frequency resources for transmitting an SRS from the UE to the BS; and

means for receiving, from the UE using the portion of the configured SRS frequency resources, the SRS at a first SRS transmission power level.
The BS of claim 89, further comprising means for:

receiving, from the UE, an indication of a capability to transmit SRSs using the portion of the configured SRS frequency resources; and

transmitting the indication to use the portion of the configured SRS frequency resources based on the indication of the capability.
The BS of claim 89, further comprising means for:

transmitting, to the UE, an indication to use the configured SRS frequency resources for transmitting a second SRS; and

receiving, from the UE using the configured SRS frequency resources, the second SRS at a second SRS transmission power level.
The BS of claim 91, wherein the first SRS transmission power level is the same as the second SRS transmission power level.
The BS of claim 91, wherein the first SRS transmission power level is different from the second SRS transmission power level.
The BS of claim 89, further means for:

transmitting, to the UE, a request for a power headroom (PHR) report; and

receiving, from the UE, the PHR report.
The BS of claim 94, the PHR report including a flag indicating the UE using the portion of the configured SRS frequency resources.
The BS of claim 94, the PHR report including a difference between the first SRS transmission power level and a second SRS transmission power level for transmitting, from the UE, a second SRS using the configured SRS frequency resources.
The BS of claim 94, wherein PHR report is a medium access control (MAC) -control element (CE) message.
The BS of claim 89, further comprising means for semi-statically configuring the first SRS transmission power level.
The BS of claim 89, wherein the first SRS transmission power level is a maximum transmission power level of the UE.
The BS of claim 89, wherein the means for transmitting the indication is further configured to:

transmit a radio resource control (RRC) message including the indication.