RRC indication to enable path loss reference signal update via MAC-CE

Abstract

A method, computer-readable medium, and apparatus for wireless communication at a user equipment are provided. The UE receives from a base station an indication that a Media Access Control-Control Element (MAC-CE) activation of a path loss reference signal is enabled. The UE receives the MAC-CE that activates the path loss reference signal. The UE determines the path loss reference signal based on the MAC-CE and the indication that the MAC-CE activation is enabled. Subsequently, the UE estimates downlink path loss based on the path loss reference signal activated by the MAC-CE.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATION(S)

[0002] This application claims the benefit of U.S. Provisional Application No. 62 / 938,919, filed on November 21, 2019, entitled “RRC Indication to Enable Pathloss Reference Signal Updates via MAC-CE,” and U.S. Patent Application No. 17 / 082,748, filed on October 28, 2020, entitled “RRC Indication to Enable Pathloss Reference Signal Updates via MAC-CE,” both of which are expressly incorporated herein by reference in their entirety. background Technical Field

[0004] The present disclosure relates generally to communication systems and, more particularly, to wireless communications including path loss reference signals.

[0005] introduction

[0006] Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcast. Typical wireless communication systems may employ multiple access technologies capable of supporting communication with multiple users by sharing available system resources. Examples of such multiple access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.

[0007] These multiple access technologies have been adopted in various telecommunication standards to provide common protocols that enable different wireless devices to communicate at city, country, region, and even global levels. An example telecommunication standard is 5G New Radio (NR). 5G NR is a part of the continuous mobile broadband evolution promulgated by the Third Generation Partnership Project (3GPP) to meet new requirements associated with latency, reliability, security, scalability (e.g., with the Internet of Things (IoT)) and other requirements. 5GNR includes services associated with enhanced mobile broadband (eMBB), massive machine type communication (mMTC), and ultra-reliable low latency communication (URLLC). Some aspects of 5G NR can be based on 4G Long Term Evolution (LTE) standards. There is a need for further improvements to 5G NR technology. These improvements can also be applied to other multiple access technologies and telecommunication standards that employ these technologies.

[0008] Overview

[0009] A brief summary of one or more aspects is given below to provide a basic understanding of such aspects. This summary is not an exhaustive overview of all conceived aspects, and is neither intended to identify the key or critical elements of all aspects nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to a more detailed description that will be presented later.

[0010] In one aspect of the present disclosure, a method, a computer-readable medium, and an apparatus for wireless communication are provided. In some examples, the apparatus may be a user equipment (UE). The apparatus receives an indication from a base station that a media access control-control element (MAC-CE) activation of a path loss reference signal is enabled. The apparatus receives a MAC-CE that activates the path loss reference signal. The apparatus determines the path loss reference signal based on the MAC-CE and an indication that the MAC-CE activation indicating the path loss reference signal is enabled. Subsequently, the UE estimates a downlink path loss based on the path loss reference signal activated by the MAC-CE.

[0011] In another aspect of the present disclosure, a method, a computer-readable medium, and an apparatus for wireless communication at a base station are provided. The apparatus transmits an indication that MAC-CE activation of a path loss reference signal is enabled to a UE. Subsequently, the apparatus transmits a MAC-CE activating the path loss reference signal based on the indication that the MAC-CE activation of the path loss reference signal is enabled.

[0012] To achieve the foregoing and related ends, the one or more aspects include the features fully described below and particularly pointed out in the claims. The following description and drawings set forth in detail certain illustrative features of the one or more aspects. However, these features are merely indicative of several of the various ways in which the principles of the various aspects may be employed, and this description is intended to cover all such aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a diagram illustrating an example of a wireless communication system and access network in accordance with various aspects presented herein.

[0015] Figure 2A , 2B , 2C, and 2D are diagrams illustrating examples of a first 5G / NR frame, a DL channel within a 5G / NR subframe, a second 5G / NR frame, and a UL channel within a 5G / NR subframe, respectively.

[0016] Figure 3 is a diagram illustrating an example of a base station and a user equipment (UE) in an access network in accordance with various aspects presented herein.

[0017] Figure 4 A communication flow between a UE and a base station including enabling MAC-CE updates for a path loss reference signal according to various aspects presented herein.

[0018] Figure 5 is a flow chart of a method of wireless communication including MAC-CE update for a path loss reference signal in accordance with various aspects presented herein.

[0019] Figure 6 is a conceptual data flow diagram illustrating the flow of data between different devices / components in an example apparatus according to various aspects presented herein.

[0020] Figure 7 is a diagram illustrating an example of a hardware implementation for a device employing a processing system in accordance with various aspects presented herein.

[0021] Figure 8 is a flow chart of a method of wireless communication including enabling MAC-CE updates for a path loss reference signal in accordance with various aspects presented herein.

[0022] Fig. 9 is a conceptual data flow diagram illustrating the flow of data between different devices / components in an example apparatus according to various aspects presented herein.

[0023] Fig.10 is a diagram illustrating an example of a hardware implementation for a device employing a processing system in accordance with various aspects presented herein.

[0024] Detailed Description

[0025] The detailed description set forth below in conjunction with the accompanying 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. This detailed description includes specific details to provide 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 diluting such concepts.

[0026] Several aspects of telecommunication systems will now be presented with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, components, circuits, processes, algorithms, etc. (collectively referred to as "elements"). These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system.

[0027] As an example, an element, or any part of an element, or any combination of elements may be implemented as a "processing system" including one or more processors. Examples of processors include: microprocessors, microcontrollers, graphics processing units (GPUs), central processing units (CPUs), application processors, digital signal processors (DSPs), reduced instruction set computing (RISC) processors, systems on chip (SoCs), baseband processors, field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gating logic, discrete hardware circuits, and other suitable hardware configured to perform various functionalities described throughout this disclosure. One or more processors in a processing system may execute software. Software should be broadly interpreted as meaning instructions, instruction sets, codes, code segments, program codes, programs, subroutines, software components, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether it is described in software, firmware, middleware, microcode, hardware description languages, or other terms.

[0028] Accordingly, in one or more example embodiments, the functions described may be implemented in hardware, software, or any combination thereof. If implemented in software, each function may be stored or encoded as one or more instructions or codes on a computer-readable medium. Computer-readable media include computer storage media. Storage media may be any available medium that can be accessed by a computer. As an example and not limitation, such computer-readable media may include random access memory (RAM), read-only memory (ROM), electrically erasable programmable ROM (EEPROM), optical disk storage, magnetic disk storage, other magnetic storage devices, a combination of the aforementioned types of computer-readable media, or any other medium that can be used to store instructions or data structures in the form of computer executable code that can be accessed by a computer.

[0029] Figure 1 1 is a diagram illustrating an example of a wireless communication system and access network 100 including base stations 102 and 180 and UE 104. The various aspects given herein enable base station 102 or base station 180 to configure UE 104 for an improved path loss reference signal. UE 104 can use the path loss reference signal identified by base station 102 or base station 180 to measure path loss and determine the transmit power for uplink signals. The various aspects given herein enable the base station to update the path loss reference signal in a more dynamic manner. As described herein, base station 102 or base station 180 may include an RRC indication component 198 configured to transmit a MAC-CE update or activation of a path loss reference signal to the UE to indicate that it is enabled. Subsequently, base station 102 or base station 180 may transmit a MAC-CE that activates a specific path loss reference signal. UE 104 may include an RRC indication receiving component 199 configured to receive a MAC-CE update or activation of a path loss reference signal from a base station to indicate that it is enabled. The UE may receive a MAC-CE that activates a specific path loss reference signal. The UE may determine a path loss reference signal based on the MAC-CE and an indication that MAC-CE activation indicating a path loss reference signal is enabled. The UE may then estimate the downlink path loss using the activated path loss reference signal. The UE may determine the transmit power for an uplink signal (e.g., SRS or PUSCH) using the estimated downlink path loss.

[0030] The wireless communication system (also referred to as a wireless wide area network (WWAN)) includes a base station 102, a UE 104, an evolved packet core (EPC) 160, and another core network 190 (e.g., a 5G core (5GC)). The base station 102 may include a macro cell (a high-power cellular base station) and / or a small cell (a low-power cellular base station). A macro cell includes a base station. A small cell includes a femto cell, a pico cell, and a micro cell.

[0031] Base stations 102 configured for 4G LTE (collectively referred to as Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) may interface with EPC 160 via a backhaul link 132 (e.g., an S1 interface). Base stations 102 configured for 5G NR (collectively referred to as Next Generation RAN (NG-RAN)) may interface with core network 190 via a backhaul link 184. Base stations 102 may perform one or more of the following functions, among other functions: delivery of user data, radio channel encryption and decryption, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection establishment and release, load balancing, distribution of non-access stratum (NAS) messages, NAS node selection, synchronization, radio access network (RAN) sharing, multimedia broadcast multicast service (MBMS), subscriber and equipment tracking, RAN information management (RIM), paging, positioning, and delivery of alert messages. The base stations 102 may communicate with each other directly or indirectly (eg, through the EPC 160 or the core network 190) via a backhaul link 134 (eg, an X2 interface). The backhaul link 134 may be wired or wireless.

[0032] Base stations 102 may communicate wirelessly with UEs 104. Each base station 102 may provide communication coverage for a respective geographic coverage area 110. There may be overlapping geographic coverage areas 110. For example, a small cell 102' may have a coverage area 110' that overlaps with the coverage area 110 of one or more macro base stations 102. A network that includes both small cells and macro cells may be referred to as a heterogeneous network. A heterogeneous network may also include a home evolved Node B (eNB) (HeNB), which may provide services to a restricted group referred to as a closed subscriber group (CSG). A communication link 120 between a base station 102 and a UE 104 may include an uplink (UL) (also referred to as a reverse link) transmission from the UE 104 to the base station 102 and / or a downlink (DL) (also referred to as a forward link) transmission from the base station 102 to the UE 104. The communication link 120 may use multiple-input multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and / or transmit diversity. These communication links may be over one or more carriers. For each carrier allocated in a carrier aggregation of up to Yx MHz (x component carriers) for transmission in each direction, the base station 102 / UE 104 may use a spectrum of up to Y MHz (e.g., 5, 10, 15, 20, 100, 400 MHz, etc.) bandwidth. These carriers may or may not be adjacent to each other. The allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated to DL compared to UL). The component carrier may include a primary component carrier and one or more secondary component carriers. The primary component carrier may be referred to as a primary cell (PCell), and the secondary component carrier may be referred to as a secondary cell (SCell).

[0033] Some UEs 104 may communicate with each other using a device-to-device (D2D) communication link 158. The D2D communication link 158 may use DL / UL WWAN spectrum. The D2D communication link 158 may use one or more sidelink channels, such as a physical sidelink broadcast channel (PSBCH), a physical sidelink discovery channel (PSDCH), a physical sidelink shared channel (PSSCH), and a physical sidelink control channel (PSCCH). The D2D communication may be through a variety of wireless D2D communication systems, such as, for example, FlashLinQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based on the IEEE 802.11 standard, LTE, or NR.

[0034] The wireless communication system may further include a Wi-Fi access point (AP) 150 communicating with a Wi-Fi station (STA) 152 in the 5 GHz unlicensed spectrum via a communication link 154. When communicating in the unlicensed spectrum, the STA 152 / AP 150 may perform a clear channel assessment (CCA) to determine whether the channel is available prior to communication.

[0035] The small cell 102' may operate in a licensed and / or unlicensed spectrum. When operating in an unlicensed spectrum, the small cell 102' may employ NR and use the same 5 GHz unlicensed spectrum as used by the Wi-Fi AP 150. The small cell 102' employing NR in the unlicensed spectrum may boost the coverage of the access network and / or increase the capacity of the access network.

[0036] Whether a small cell 102' or a large cell (e.g., a macro base station), the base station 102 may include an eNB, a gB node (gNB), or another type of base station. Some base stations (such as gNB 180) may operate in traditional sub-6 GHz spectrum, millimeter wave (mmW) frequencies, and / or near mmW frequencies to communicate with UE 104. When gNB 180 operates in mmW or near mmW frequencies, gNB 180 may be referred to as a mmW base station. Extremely high frequency (EHF) is part of the RF in the electromagnetic spectrum. EHF has a range of 30 GHz to 300 GHz and a wavelength between 1 mm and 10 mm. The radio waves in this band may be referred to as millimeter waves. Near mmW can be extended down to 3 GHz frequencies with a wavelength of 100 mm. The super high frequency (SHF) band extends between 3 GHz and 30 GHz, which is also referred to as centimeter waves. Communications using mmW / near mmW radio frequency bands (e.g., 3 GHz–300 GHz) have extremely high path loss and short range. The mmW base station 180 may utilize beamforming 182 with the UE 104 to compensate for the extremely high path loss and short range.

[0037] The base station 180 may transmit beamformed signals to the UE 104 in one or more transmit directions 182'. The UE 104 may receive beamformed signals from the base station 180 in one or more receive directions 182". The UE 104 may also transmit beamformed signals to the base station 180 in one or more transmit directions. The base station 180 may receive beamformed signals from the UE 104 in one or more receive directions. The base station 180 / UE 104 may perform beam training to determine the best receive direction and transmit direction for each of the base station 180 / UE 104. The transmit direction and receive direction of the base station 180 may be the same or may be different. The transmit direction and receive direction of the UE 104 may be the same or may be different.

[0038] The EPC 160 may include a mobility management entity (MME) 162, other MMEs 164, a serving gateway 166, a multimedia broadcast multicast service (MBMS) gateway 168, a broadcast multicast service center (BM-SC) 170, and a packet data network (PDN) gateway 172. The MME 162 may be in communication with a home subscriber server (HSS) 174. The MME 162 is a control node that handles signaling between the UE 104 and the EPC 160. In general, the MME 162 provides bearer and connection management. All user Internet Protocol (IP) packets are delivered through the serving gateway 166, which itself is connected to the PDN gateway 172. The PDN gateway 172 provides UE IP address allocation and other functions. The PDN gateway 172 and the BM-SC 170 are connected to IP services 176. The IP services 176 may include the Internet, an intranet, an IP multimedia subsystem (IMS), a PS streaming service, and / or other IP services. The BM-SC 170 may provide functionality for MBMS user service provisioning and delivery. The BM-SC 170 may serve as an entry point for content provider MBMS transmissions, may be used to authorize and initiate MBMS bearer services within a public land mobile network (PLMN), and may be used to schedule MBMS transmissions. The MBMS gateway 168 may be used to distribute MBMS traffic to base stations 102 belonging to a multicast broadcast single frequency network (MBSFN) area that broadcasts a specific service, and may be responsible for session management (start / stop) and for collecting eMBMS-related charging information.

[0039] The core network 190 may include an access and mobility management function (AMF) 192, other AMFs 193, a session management function (SMF) 194, and a user plane function (UPF) 195. AMF 192 may be in communication with a unified data management (UDM) 196. AMF 192 is a control node that handles signaling between UE 104 and the core network 190. In general, AMF 192 provides QoS flow and session management. All user Internet Protocol (IP) packets are delivered through UPF 195. UPF 195 provides UE IP address allocation and other functions. UPF 195 is connected to IP services 197. IP services 197 may include the Internet, an intranet, an IP multimedia subsystem (IMS), a PS streaming service, and / or other IP services.

[0040] A base station may also be referred to as a gNB, a Node B, an evolved Node B (eNB), an access point, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), a transmission reception point (TRP), or some other suitable term. The base station 102 provides an access point to the EPC 160 or the core network 190 for the UE 104. Examples of UE 104 include a cellular phone, a smart phone, a Session Initiation Protocol (SIP) phone, a laptop, a personal digital assistant (PDA), a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., an MP3 player), a camera, a game console, a tablet device, a smart device, a wearable device, a vehicle, an electric meter, a gas pump, a large or small kitchen appliance, a health care device, an implant, a sensor / actuator, a display, or any other similar functional device. Some UEs 104 may be referred to as IoT devices (e.g., parking meters, gas pumps, ovens, vehicles, heart monitors, etc.). UE 104 may also be referred to as a station, a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communication device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology.

[0041] Although the following description may focus on 5G NR, the concepts described herein may be applicable to other similar areas such as LTE, LTE-A, CDMA, GSM, and other wireless technologies.

[0042] Figure 2A 200 is a diagram illustrating an example of a first subframe within a 5G / NR frame structure. Figure 2B FIG230 is a diagram illustrating an example of DL channels within a 5G / NR subframe. Figure 2C FIG250 is a diagram illustrating an example of a second subframe within a 5G / NR frame structure. Figure 2D 280 is a diagram illustrating an example of an UL channel within a 5G / NR subframe. The 5G / NR frame structure may be FDD, where for a particular set of subcarriers (carrier system bandwidth), subframes within that subcarrier set are dedicated to either DL or UL, or TDD, where for a particular set of subcarriers (carrier system bandwidth), subframes within that subcarrier set are dedicated to both DL and UL. Figure 2A , 2CIn the example provided, the 5G / NR frame structure is assumed to be TDD, where subframe 4 is configured with slot format 28 (mostly DL) and subframe 3 is configured with slot format 34 (mostly UL), where D is DL, U is UL, and X is for flexible use between DL / UL. Although subframes 3 and 4 are shown as having slot formats 34 and 28, respectively, any particular subframe may be configured with any of the various available slot formats 0-61. Slot formats 0 and 1 are full DL and full UL, respectively. Other slot formats 2-61 include a mixture of DL, UL, and flexible symbols. The UE is configured with a slot format (dynamically configured by DL control information (DCI) or semi-statically / statically configured by radio resource control (RRC) signaling) through the received slot format indicator (SFI). Note that the following description also applies to the 5G / NR frame structure for TDD.

[0043] Other wireless communication technologies may have different frame structures and / or different channels. A frame (10ms) may be divided into 10 equally sized subframes (1ms). Each subframe may include one or more time slots. A subframe may also include mini-slots, which may include 7, 4, or 2 symbols. Each time slot may include 7 or 14 symbols, depending on the time slot configuration. For time slot configuration 0, each time slot may include 14 symbols, and for time slot configuration 1, each time slot may include 7 symbols. The symbols on the DL may be cyclic prefix (CP) OFDM (CP-OFDM) symbols. The symbols on the UL may be CP-OFDM symbols (for high throughput scenarios) or discrete Fourier transform (DFT) spread OFDM (DFT-s-OFDM) symbols (also known as single carrier frequency division multiple access (SC-FDMA) symbols) (for power-limited scenarios; limited to single stream transmission). The number of time slots within a subframe is based on the time slot configuration and parameter design. For slot configuration 0, different parameter designs μ of 0 to 5 allow 1, 2, 4, 8, 16, and 32 slots per subframe, respectively. For slot configuration 1, different parameter designs 0 to 2 allow 2, 4, and 8 slots per subframe, respectively. Accordingly, for slot configuration 0 and parameter design μ, there are 14 symbols per slot and 2 per subframe. μ time slots. The subcarrier spacing and symbol length / duration are a function of the parameter design. The subcarrier spacing may be equal to 2^μ*15kHz, where μ is a parameter design 0 to 5. Thus, parameter design μ=0 has a subcarrier spacing of 15kHz, while parameter design μ=5 has a subcarrier spacing of 480kHz. The symbol length / duration is inversely related to the subcarrier spacing. Figures 2A-2D An example of slot configuration 0 with 14 symbols per slot and parameter design μ=0 with 1 slot per subframe is provided. The subcarrier spacing is 15 kHz and the symbol duration is about 66.7 μs.

[0044] A resource grid may be used to represent the frame structure. Each slot includes a resource block (RB) (also called a physical RB (PRB)) extending over 12 consecutive subcarriers. The resource grid is divided into a number of resource elements (REs). The number of bits carried by each RE depends on the modulation scheme.

[0045] like Figure 2A As illustrated in FIG, some REs carry reference (pilot) signals (RS) for UEs. RSs may include demodulation RSs (DM-RSs) for channel estimation at the UE (indicated as Rx for one specific configuration, where 100x is the port number, but other DM-RS configurations are possible) and channel state information reference signals (CSI-RSs). RSs may also include beam measurement RSs (BRSs), beam refinement RSs (BRRSs), and phase tracking RSs (PT-RSs).

[0046] Figure 2B An example of various DL channels within a subframe of an explanation frame. The physical downlink control channel (PDCCH) carries DCI within one or more control channel elements (CCEs), each CCE includes 9 RE groups (REGs), and each REG includes 4 consecutive REs in an OFDM symbol. The primary synchronization signal (PSS) may be within symbol 2 of a particular subframe of a frame. The PSS is used by the UE 104 to determine the subframe / symbol timing and the physical layer identity. The secondary synchronization signal (SSS) may be within symbol 4 of a particular subframe of a frame. The SSS is used by the UE to determine the physical layer cell identity group number and the radio frame timing. Based on the physical layer identity and the physical layer cell identity group number, the UE may determine the physical cell identifier (PCI). Based on the PCI, the UE may determine the location of the aforementioned DM-RS. The physical broadcast channel (PBCH) carrying the master information block (MIB) may be logically grouped with the PSS and SSS to form a synchronization signal (SS) / PBCH block. The MIB provides the number of RBs in the system bandwidth, as well as the system frame number (SFN). The Physical Downlink Shared Channel (PDSCH) carries user data, broadcast system information not transmitted through the PBCH (such as System Information Blocks (SIBs)), and paging messages.

[0047] As in Figure 2CAs illustrated in FIG, some REs carry DM-RSs for channel estimation at the base station (indicated as R for one particular configuration, but other DM-RS configurations are possible). The UE may transmit DM-RSs for the physical uplink control channel (PUCCH) and DM-RSs for the physical uplink shared channel (PUSCH). The PUSCH DM-RS may be transmitted in the first or first two symbols of the PUSCH. The PUCCH DM-RS may be transmitted in different configurations depending on whether a short PUCCH or a long PUCCH is transmitted and on the specific PUCCH format used. Although not shown, the UE may transmit a sounding reference signal (SRS). The SRS may be used by the base station for channel quality estimation to enable frequency-dependent scheduling on the UL.

[0048] Figure 2D An example of various UL channels within a subframe of an illustration frame. The PUCCH may be located at a position as indicated in one configuration. The PUCCH carries uplink control information (UCI), such as scheduling requests, channel quality indicator (CQI), precoding matrix indicator (PMI), rank indicator (RI), and HARQ ACK / NACK feedback. The PUSCH carries data and may additionally be used to carry a buffer status report (BSR), a power headroom report (PHR), and / or UCI.

[0049] Figure 33 is a block diagram of a base station 310 in communication with a UE 350 in an access network. In the DL, IP packets from the EPC 160 may be provided to a controller / processor 375. The controller / processor 375 implements layer 3 and layer 2 functionality. Layer 3 includes a radio resource control (RRC) layer, and layer 2 includes a service data adaptation protocol (SDAP) layer, a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, and a media access control (MAC) layer. The controller / processor 375 provides RRC layer functionality associated with broadcasting of system information (e.g., MIB, SIB), RRC connection control (e.g., RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release), inter-radio access technology (RAT) mobility, and measurement configuration of UE measurement reports; PDCP layer functionality associated with header compression / decompression, security (ciphering, cipher decryption, integrity protection, integrity verification), and handover support functions; RLC layer functionality associated with delivery of upper layer packet data units (PDUs), error correction through ARQ, concatenation, segmentation and reassembly of RLC service data units (SDUs), re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto transport blocks (TBs), demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

[0050] The transmit (TX) processor 316 and the receive (RX) processor 370 implement layer 1 functionality associated with various signal processing functions. Layer 1, including the physical (PHY) layer, may include error detection on the transport channel, forward error correction (FEC) encoding / decoding of the transport channel, interleaving, rate matching, mapping to the physical channel, modulation / demodulation of the physical channel, and MIMO antenna processing. The TX processor 316 handles the mapping to the signal constellation based on various modulation schemes (e.g., binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), M-phase shift keying (M-PSK), M-quadrature amplitude modulation (M-QAM)). The coded and modulated symbols may then be split into parallel streams. Each stream may then be mapped to an OFDM subcarrier, multiplexed with a reference signal (e.g., pilot) in the time domain and / or frequency domain, and then combined together using an inverse fast Fourier transform (IFFT) to produce a physical channel carrying a time domain OFDM symbol stream. The OFDM stream is spatially precoded to generate multiple spatial streams. Channel estimates from a channel estimator 374 may be used to determine coding and modulation schemes and for spatial processing. The channel estimates may be derived from reference signals and / or channel condition feedback transmitted by the UE 350. Each spatial stream may then be provided to a different antenna 320 via a separate transmitter 318TX. Each transmitter 318TX may modulate an RF carrier with a corresponding spatial stream for transmission.

[0051] At the UE 350, each receiver 354RX receives a signal through its corresponding antenna 352. Each receiver 354RX recovers the information modulated onto the RF carrier and provides the information to a receive (RX) processor 356. The TX processor 368 and the RX processor 356 implement layer 1 functionality associated with various signal processing functions. The RX processor 356 can perform spatial processing on the information to recover any spatial stream destined for the UE 350. If there are multiple spatial streams destined for the UE 350, they can be combined into a single OFDM symbol stream by the RX processor 356. The RX processor 356 then transforms the OFDM symbol stream from the time domain to the frequency domain using a fast Fourier transform (FFT). The frequency domain signal includes a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier, as well as the reference signal, are recovered and demodulated by determining the signal constellation point most likely transmitted by the base station 310. These soft decisions can be based on the channel estimates calculated by the channel estimator 358. These soft decisions are then decoded and deinterleaved to recover the data and control signals originally transmitted on the physical channel by the base station 310. These data and control signals are then provided to the controller / processor 359 which implements layer 3 and layer 2 functionality.

[0052] The controller / processor 359 may be associated with a memory 360 that stores program codes and data. The memory 360 may be referred to as a computer readable medium. In the UL, the controller / processor 359 provides demultiplexing between transport channels and logical channels, packet reassembly, cipher interpretation, header decompression, and control signal processing to recover IP packets from the EPC 160. The controller / processor 359 is also responsible for error detection using ACK and / or NACK protocols to support HARQ operations.

[0053] Similar to the functionality described in conjunction with DL transmissions performed by the base station 310, the controller / processor 359 provides RRC layer functionality associated with system information (e.g., MIB, SIB) acquisition, RRC connection, and measurement reporting; PDCP layer functionality associated with header compression / decompression, and security (encryption, decryption, integrity protection, integrity verification); RLC layer functionality associated with delivery of upper layer PDUs, error correction through ARQ, concatenation, segmentation, and reassembly of RLC SDUs, resegmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing MAC SDUs onto TBs, demultiplexing MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

[0054] Channel estimates derived by a channel estimator 358 from a reference signal or feedback transmitted by the base station 310 may be used by a TX processor 368 to select the appropriate coding and modulation schemes, and to facilitate spatial processing. The spatial streams generated by the TX processor 368 may be provided to different antennas 352 via separate transmitters 354TX. Each transmitter 354TX may modulate an RF carrier with a corresponding spatial stream for transmission.

[0055] UL transmissions are processed at the base station 310 in a manner similar to that described in conjunction with the receiver functionality at the UE 350. Each receiver 318RX receives a signal through its respective antenna 320. Each receiver 318RX recovers information modulated onto an RF carrier and provides the information to a RX processor 370.

[0056] The controller / processor 375 may be associated with a memory 376 that stores program codes and data. The memory 376 may be referred to as a computer readable medium. In the UL, the controller / processor 375 provides demultiplexing between transport channels and logical channels, packet reassembly, cipher decoding, header decompression, control signal processing to recover IP packets from the UE 350. The IP packets from the controller / processor 375 may be provided to the EPC 160. The controller / processor 375 is also responsible for error detection using ACK and / or NACK protocols to support HARQ operations.

[0057] At least one of the TX processor 368, the RX processor 356, and the controller / processor 359 may be configured to perform operations related to Figure 1 The 199 combines all aspects.

[0058] At least one of the TX processor 316, the RX processor 370, and the controller / processor 375 may be configured to perform operations related to Figure 1 The 198 combined aspects.

[0059] The communication between the base station and the UE may need to adapt to changes in the wireless channel. One adaptation may include power control. The transmitted power may vary based on the channel quality. Power control may be applied to downlink transmissions and uplink transmissions. Uplink power control can help avoid interference caused by uplink transmissions and reduce UE power consumption while ensuring that uplink transmissions can be accurately received by the base station. The UE may increase the transmit power to compensate for the increased path loss. In order to determine the path loss, the UE may measure a reference signal (such as a path loss reference signal) from the base station to determine the path loss. The UE may use the path loss measurement together with other factors to determine the transmit power for the uplink transmission transmitted by the UE.

[0060] The path loss reference signal may be configured for an uplink signal of the UE, an uplink channel for the UE, etc. For example, the path loss reference signal may be configured for the UE to use in power control of a sounding reference signal (SRS), a PUSCH, and / or a PUCCH.

[0061] The path loss reference signal may be updated, for example, by a media access control-control element (MAC-CE). For example, the base station may use RRC signaling to configure a path loss reference signal set for SRS at the UE. Subsequently, the base station may activate a path loss reference signal for a specific uplink signal, each activated path loss reference signal being from a configured path loss reference signal set. The configured path loss reference signal set may be referred to as a configured path loss reference signal pool.

[0062] As presented herein, the base station may provide an indication to the UE informing the UE whether a feature for updating a path loss reference signal via MAC-CE is enabled. The base station may use signaling flag(s) to inform the UE that a feature for updating a path loss via MAC-CE is enabled. Figure 4 An example communication flow 400 including signaling 405 between a base station 402 and a UE 404 to enable MAC-CE updates for a path loss reference signal is illustrated. In an example, the base station 402 may send an RRC configuration at 405 to enable MAC-CE updates for a path loss reference signal. As an example, if the UE 404 receives an indication in the RRC signaling that path loss reference signal updates (e.g., for SRS and / or PUSCH) are enabled, the UE may receive an indication in the MAC-CE to update the path loss reference signal, (e.g., at 407). For example, the MAC-CE may include an ID for the activated path loss reference signal. If the indication is not present in the RRC signaling (e.g., if the UE does not receive the indication at 405), the UE 404 may determine that the path loss reference signal may not be updated via the MAC-CE.

[0063] Updates enabled via MAC-CE for the path loss reference signal (PL RS) may include any combination of sub-features: such as (1) path loss reference signal updates for SRS via MAC-CE; (2) path loss reference signal for PUSCH scheduled by DCI with an SRI field; (3) path loss reference signal for PUSCH not scheduled by DCI with SRI; or (4) path loss reference signal for PUSCH (such as a combination of sub-features 2 & 3).

[0064] In some examples, MAC-CE updates may be enabled for path loss reference signals for SRS and PUSCH. In some examples, MAC-CE updates may be enabled for path loss reference signals for SRS and PUSCH scheduled by DCI with an SRI field. In some examples, for updates of path loss reference signals for PUSCH scheduled by a DCI format that does not include an SRI field (e.g., DCI format 0_1, etc.), when path loss updates via MAC-CE are enabled, the path loss reference signal may be determined based on a default SRI (e.g., SRI-PUSCH-PowerControlId=0).

[0065] In some examples, the base station 402 may use a single indication at 405 to indicate that MAC-CE updates are enabled for path loss reference signals for multiple uplink signals. For example, a single indication may indicate that MAC-CE updates for path loss reference signals for SRS and PUSCH are enabled for the UE 404. In some examples, the base station 402 may use a single flag to enable all sub-features or individual sub-features of updating the path loss reference signal via MAC-CE. In other examples, the base station 402 may use individual flags at 405 to indicate whether different sub-features are enabled for the UE 404. When the base station 402 receives UE capability signaling 401 from the UE 404 indicating that the UE 404 supports MAC-CE updates for path loss reference signals for one or more uplink signals, the base station 402 may set a flag, for example, to provide an indication to the UE 404 at 405.

[0066] The flag or indication at 405 may be explicit, for example, an explicit indication in an RRC / MAC-CE / DCI message. In a first example, the base station 402 may send an indication to the UE in RRC signaling (e.g., 405) indicating that MAC-CE updates for path loss reference signals for one or more uplink signals (e.g., SRS, PUSCH, etc.) are enabled (e.g., "enable PLRS updates for PUSCH SRS"). In another example, the base station 402 may send an indication to the UE 404 in a MAC-CE at 405 indicating that MAC-CE updates for path loss reference signals for one or more uplink signals are enabled. In another example, the base station 402 may send a DCI at 405 including an indication that MAC-CE updates for path loss reference signals for one or more uplink signals are enabled. In some examples, the flag or indication may be implicit. For example, when a corresponding MAC-CE to update the path loss reference signal is sent to the UE 404, the base station may indicate that MAC-CE updates for the path loss reference signal are enabled.

[0067] In some examples, base station 402 can use the flag independently of the number of configured path loss reference signals, e.g., provide indication 405 to UE 404. For example, a sub-feature can be enabled regardless of the number of configured path loss reference signals. In some examples, base station 402 can use the flag, or provide indication 405 to UE 404, when the number of configured path loss reference signals for the UE meets a threshold (e.g., exceeds a threshold number thereof). In one example, base station 402 can use the flag when the number of configured path loss reference signals exceeds 4. For example, the sub-feature can be enabled when the number of configured path loss reference signals exceeds a threshold number.

[0068] UE 404 may perform filtering (such as L3 filtering) upon activation of the path loss reference signal, for example, as part of measuring the path loss at 413. The filtering may help UE 404 determine a more stable path loss value for SRS power control (e.g., at 415). SRS may include aperiodic SRS (AP-SRS) and / or semi-persistent SRS (SP-SRS). Thus, at 407, the path loss reference signal(s) for AP-SRS / SP-SRS may be activated or updated by the base station using MAC-CE.

[0069] UE 404 may be configured with multiple path loss reference signals through RRC signaling from a base station at 403 , and one of the configured path loss reference signals may be activated / updated by MAC-CE for a specific SRS resource set at 407 based on enabling of MAC-CE update at 405 .

[0070] The base station 402 may use MAC-CE to update a path loss reference signal per SRS resource indicator (SRI) associated with a PUSCH transmission at 407. For example, the base station 402 may use RRC signaling to configure a set of path loss reference signals for the UE at 403. Subsequently, at 407, the base station 402 may activate a path loss reference signal per SRI, each activated path loss reference signal from the configured set of path loss reference signals. The UE may perform L3 filtering of each activated path loss reference signal 411, for example, as part of measuring path loss at 413. L3 filtering may help the UE determine a more stable path loss value for PUSCH power control at 413. As illustrated at 415, the UE 404 may use the path loss determined at 413 for the identified path loss reference signal to determine uplink power control at 415. Subsequently, the UE 404 may apply the transmit power determined at 415 to transmit an uplink signal (such as SRS, PUSCH, PUCCH, etc.) at 415. Thus, a MAC-CE message (e.g., 407) from the base station 402 may activate / update a value of a PUSCH path loss reference signal identifier (ID) (which value may be referred to as, for example, a parameter, such as "PUSCH-Path Loss Reference RS-Id"). When the MAC-CE update is enabled at 405, the UE 404 may use the information provided in the MAC-CE at 407 to identify a path loss reference signal for performing downlink path loss estimation. For example, the UE 404 may use the information received in the MAC-CE at 407 to identify a reference signal resource index for the path loss reference signal at 409. For example, the UE 404 may determine that the PUSCH path loss reference signal ID corresponds to a SRI PUSCH power control ID (which may be referred to as a parameter, such as "sri-PUSCH-Power Control Id"). The mapping may be given by a SRI PUSCH power control with a link between the SRI PUSCH power control ID and the PUSCH path loss reference signal ID. UE 404 may use the mapping at 409 to determine path loss reference signal resources to use at 413 to perform path loss estimation.

[0071] The higher layer filtered reference signal received power (RSRP) can be used for path loss measurement. The base station 402 can provide an amount of time after the MAC-CE (e.g., 407) for the UE 404 to perform path loss measurement. For example, the filtered RSRP value for the previous path loss reference signal can be used until a specific time, which can be referred to as the application time. For example, the application time can be the next time slot after the fifth measurement sample, where the first measurement sample corresponds to the first instance of the path loss reference signal. The first instance of the path loss reference signal can be, for example, 3ms later than the UE sends an ACK in response to receiving a MAC-CE activating the path loss reference signal.

[0072] Activation of the configured path loss reference signal via MAC-CE may be applicable to UEs that support more than four RRC configurable path loss reference signals and may be applicable when the path loss reference signal activated by the MAC-CE is not tracked by the UE 404. In some examples, if more than four path loss reference signals are configured in the RRC signaling from the base station, the UE 404 may track the activated path loss reference signal(s). The UE 404 may determine whether to update the filtered RSRP value for the previous path loss reference signal, for example, 3 ms later than sending an ACK in response to a MAC-CE (e.g., 407) activating a new path loss reference signal.

[0073] When the PUSCH (e.g., 415) is scheduled by DCI format 0_1, the DCI may not have an SRI field. At 409, the UE may determine that the path loss reference signal (e.g., 411) used for PUSCH transmission may be determined based on a default SRI (e.g., in the case of ID 0). The default SRI may be semi-statically configured by RRC and is not dynamically updated, for example, when the transmit beam of the SRS resource is updated.

[0074] If a grant-based or non-grant-based PUSCH transmission (e.g., grant-based PUSCH, non-grant PUSCH, configured grant PUSCH, etc.) is scheduled / activated by DCI format 0_1 ​​that does not include the SRI field, the RS resource index used for path loss estimation (e.g., qd) can be based on the PUSCH path loss reference signal ID (e.g., "PUSCH-PathLoss-Reference RS-Id") mapped to the default SRI PUSCH power control ID (e.g., "sri-PUSCH-PowerControlId=0").

[0075] In some examples, UE 404 may determine path loss reference signal resources based on a default SRI ID based on the number of path loss reference signals configured for PUSCH. For example, this determination of path loss reference signals may be applied when the number of PUSCH path loss RSs configured by RRC is greater than a threshold number (such as 4). This determination of RS resources for path loss measurement may be applied based on UE support for a MAC-CE update-based feature for PUSCH path loss reference signals. If UE 404 does not support a MAC-CE update-based feature for path loss reference signals for PUSCH(s), the UE may determine path loss reference signals for PUSCH in a different manner.

[0076] An RRC information element (IE) such as a SRI PUSCH power control IE may be configured with at least a SRI PUSCH power control identifier (ID). As an example, a SRI PUSCH power control ID=X may be configured, where X is a fixed ID (such as 0). If, for example at 405, a feature of path loss reference signal update via MAC-CE is enabled for UE 404, the SRI PUSCH power control ID may provide default SRI information that UE 404 may use to determine a path loss reference signal for a PUSCH scheduled by a DCI without SRI (e.g., DCI format 0_1).

[0077] When a flag or other indication from the base station at 405 enables a feature of path loss reference signal update via MAC-CE for PUSCH not scheduled by DCI with SRI, an RRC information element (IE) may be included. When a flag or other indication from the base station 402 enables a feature of path loss reference signal update typically via MAC-CE, an RRC information element may be included. When the UE 404 indicates support for a feature of path loss reference signal update via MAC-CE for PUSCH not scheduled by DCI with SRI at 401, an RRC information element may be included. When the UE 404 indicates support for a feature of path loss reference signal update via MAC-CE for PUSCH at 401, an RRC information element may be included. When the UE 404 indicates support for a feature of path loss reference signal update typically via MAC-CE at 401, an RRC information element may be included.

[0078] In some examples, path loss reference signal updates via MAC-CE may be enabled when the number of configured path loss reference signals exceeds a threshold number, such as 4. Four is just one example to illustrate the concept, and the threshold number may be a number other than 4.

[0079] In some examples, features of path loss reference signal updates via MAC-CE can be enabled independently of the number of configured path loss reference signals. For example, these features can be enabled when the number of configured path loss reference signals is more than four and less than four. As discussed above, MAC-CE updates for path loss reference signals can include any of the following: path loss reference signal updates for SRS via MAC-CE; path loss reference signal updates for PUSCH scheduled by DCI with SRI field; path loss reference signal updates for PUSCH not scheduled by DCI with SRI; or path loss reference signal updates for PUSCH.

[0080] For PUSCH scheduled by DCI format 0_0 on a cell, UE 404 may transmit the PUSCH within the active uplink bandwidth part (UL BWP) of the cell according to the spatial relation (corresponding to the dedicated PUCCH resource with the lowest ID and the configured PUCCH spatial relation information (e.g., “PUCCH-spatial relation information”), if applicable.

[0081] If a PUSCH transmission is scheduled by DCI format 0_0, and if a spatial setting for a PUCCH resource with a lowest index and the configured PUCCH spatial relationship information for an active UL BWP for each carrier and serving cell is provided to UE 404 by PUCCH spatial relationship information (e.g., "PUCCH-spatial relationship information"), UE 404 may use the same RS resource index as for PUCCH transmission in the PUCCH resource with the lowest index and the configured PUCCH spatial relationship information.

[0082] UE 404 may not expect PUSCH scheduled by DCI format 0_0 in a BWP without configured PUCCH resources with PUCCH spatial relation information, or in a BWP with configured PUCCH resource(s) but the PUCCH resource with the lowest resource ID does not have PUCCH spatial relation information configured in frequency range 2 of RRC connected mode.

[0083] PUSCH may be scheduled by DCI format 0_0 on a CC in FR2 and in RRC connected mode with configured PUCCH resource(s), where the configured PUCCH resource with the lowest ID is not configured with any spatial relationship. The spatial relationship and PL RS for PUSCH scheduled by DCI format 0_0 may follow those for PUCCH resource(s), which are the default spatial relationship and default path loss RS, respectively.

[0084] Figure 5 5 is a flow chart of a method of wireless communication. The method may be performed by a UE or a component of a UE (e.g., UE 104, 350, 404, device 602 / 602'; processing system 714, which may include a processing system including memory 360 and may be the entire UE 350 or a component of the UE 350 (such as TX processor 368, RX processor 356 and / or controller / processor 359)). Optional aspects are illustrated with dashed lines. The method may enable the UE to perform more accurate path loss reference signal estimation by enabling more dynamic updates to the path loss reference signal.

[0085] At 506, the UE receives an indication from the base station that MAC-CE activation of the path loss reference signal is enabled. This reception may be performed, for example, by Figure 6 The indication may be performed by a receiving component 604 and / or an enabling component 608 of a device 602. The indication may be received in RRC signaling. The indication may enable MAC-CE activation for a path loss reference signal for a specific uplink signal. For example, the indication may enable MAC-CE activation for a path loss reference signal for an SRS. The indication may enable MAC-CE activation for a path loss reference signal update for a PUSCH. The indication may enable MAC-CE activation for a path loss reference signal update for a PUSCH scheduled by a DCI having an SRI field. The indication may enable MAC-CE activation for a path loss reference signal for a PUSCH scheduled based on a DCI format without an SRI field. The indication may indicate to the UE that the path loss reference signal is to be identified based on a default SRI. As illustrated in 504, the UE may receive a configuration of a default SRI in an RRC configuration. The reception may be, for example, by Figure 6602 of the device 602. As described, in some examples, the UE can receive different indications to enable MAC-CE activation of path loss reference signals for different uplink signals. In other examples, the UE can receive a single indication that enables MAC-CE activation of path loss reference signals for multiple uplink signals. The indication can include a single indication that enables MAC-CE activation for path loss reference signals for SRS and PUSCH. The indication can include a combination of, for example, Figure 4 Any aspects described in indication 405.

[0086] At 508, the UE receives a MAC-CE activating a path loss reference signal. This reception may be performed, for example, by Figure 6 The MAC-CE component 610 of the device 602 may be executed by the receiving component 604 and / or the MAC-CE component 610. The MAC-CE may include a reference signal ID for a path loss reference signal activated by the MAC-CE. The MAC-CE may indicate or update a mapping between a path loss reference signal ID and an SRI for physical uplink shared channel power control. The MAC-CE update may include combining Figure 4 Aspects described in MAC-CE 407 in.

[0087] As illustrated at 502, the UE may receive a configuration for the UE in an RRC configuration with a set of one or more path loss reference signals. Subsequently, based on the activation at 506, the MAC-CE may activate at least one of the one or more path loss reference signals. The reception may be performed, for example, by Figure 6 The path loss reference signal component 618 of the device 602 is performed.

[0088] At 510, the UE may determine a path loss reference signal based on the MAC-CE and an indication that MAC-CE activation of the path loss reference signal is enabled. This determination may be made, for example, by Figure 6 For example, the UE may identify the path loss, such as in combination with Figure 4 For example, if the UE is enabled with the MAC-CE activation of the path loss reference signal at 506, the UE may determine the path loss reference signal based on the information in the MAC-CE, for example, as combined with Figure 4 as described.

[0089] As illustrated at 512, the UE may estimate the downlink path loss based on the determined path loss reference signal, for example, a path loss reference signal activated by the MAC-CE. For example, the UE may estimate the path loss using a reference signal, such as in conjunction with Figure 4The estimate can be made, for example, by Figure 6 The path loss measurement component 614 of the device 602 is performed.

[0090] At 514, the UE may determine a transmit power for the uplink signal based at least in part on the estimated downlink path loss. For example, the UE may determine the transmit power, such as in combination with Figure 4 This determination can be made, for example, by Figure 6 The power component 616 of the device 602 is used to perform.

[0091] At 516, the UE may transmit an uplink signal using the determined transmit power. Thus, the MAC-CE update of the path loss reference signal may be used by the UE for transmit power control, e.g., as combined with Figure 4 The transmission may be, for example, Figure 6 The transmission component 606 of the device 602 is executed.

[0092] in this way, Figure 5 Each block in the foregoing flow chart may be performed by a component of the UE (such as the RRC flag receiving component 199) and the UE may include one or more of these components. These components may be one or more hardware components specifically configured to perform the process / algorithm, implemented by a processor configured to perform the process / algorithm, stored in a computer-readable medium for implementation by a processor, or some combination thereof.

[0093] Figure 6 6 is a conceptual data flow diagram 600 illustrating data flow between different devices / components in an example device 602. The device can be a UE or a component of a UE. The device 602 includes a receiving component 604 configured to receive downlink communications from a base station 650, and a transmitting component 606 configured to transmit uplink communications to the base station 650. The device 602 includes an enabling component 608 configured to receive an indication from the base station that MAC-CE activation of a path loss reference signal is enabled, e.g., as described in conjunction with Figure 5 The apparatus includes a MAC-CE component 610 configured to receive a MAC-CE that activates a path loss reference signal, for example, as described in conjunction with Figure 5 The device 602 includes a determining component 612 configured to determine a path loss reference signal based on the MAC-CE and the indication that the MAC-CE activation is enabled, for example, as combined with Figure 5 The device 602 may include a path loss reference signal component 618 configured to receive a set of one or more path loss reference signals for the UE in an RRC configuration, for example, as described in conjunction with Figure 5Device 602 may include an SRI component 620 configured to receive a configuration of a default SRI, for example, as described in conjunction with Figure 5 The device 602 may include a path loss measurement component 614 configured to estimate the downlink path loss based on the determined path loss reference signal, for example, as described in conjunction with Figure 5 The device 602 may include a power component 616 configured to determine a transmit power for an uplink signal based at least in part on the downlink path loss, for example, as described in conjunction with Figure 5 The transmission component 606 can be configured to transmit the uplink signal using the determined transmit power, for example, as described in conjunction with Figure 5 As described in 516.

[0094] The device may include executing Figure 5 The various blocks of the algorithms in the aforementioned flow charts and the additional components of various aspects performed by UE 404. Thus, Figure 5 Each block in the aforementioned flow chart and various aspects performed by UE 404 may be performed by a component and the device may include one or more of these components. These components may be one or more hardware components specifically configured to perform the process / algorithm, implemented by a processor configured to perform the process / algorithm, stored in a computer-readable medium for implementation by a processor, or some combination thereof.

[0095] Figure 7 7 is a diagram 700 illustrating an example of a hardware implementation of a device 602' employing a processing system 714. The processing system 714 may be implemented with a bus architecture generally represented by a bus 724. Depending on the specific application of the processing system 714 and the overall design constraints, the bus 724 may include any number of interconnecting buses and bridges. The bus 724 links together various circuits, including one or more processors and / or hardware components (represented by the processor 704, components 604, 606, 608, 610, 612, 614, 616, 618, 620, and computer readable medium / memory 706). The bus 724 may also link various other circuits, such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art and therefore will not be described further.

[0096] The processing system 714 may be coupled to the transceiver 710. The transceiver 710 is coupled to one or more antennas 720. The transceiver 710 provides a means for communicating with various other devices via a transmission medium. The transceiver 710 receives signals from the one or more antennas 720, extracts information from the received signals, and provides the extracted information to the processing system 714 (specifically, the receiving component 604). In addition, the transceiver 710 receives information from the processing system 714 (specifically, the transmission component 606) and generates signals to be applied to the one or more antennas 720 based on the received information. The processing system 714 includes a processor 704 coupled to a computer-readable medium / memory 706. The processor 704 is responsible for general processing, including the execution of software stored on the computer-readable medium / memory 706. The software, when executed by the processor 704, causes the processing system 714 to perform the various functions described above for any particular device. The computer-readable medium / memory 706 may also be used to store data manipulated by the processor 704 when executing the software. The processing system 714 further includes at least one of the components 604, 606, 608, 610, 612, 614, 616, 618, 620. These components may be software components running in the processor 704, software components resident / stored in the computer-readable medium / memory 706, one or more hardware components coupled to the processor 704, or some combination thereof. The processing system 714 may be a component of the UE 350 and may include the memory 360 and / or at least one of the following: the TX processor 368, the RX processor 356, and the controller / processor 359. Alternatively, the processing system 714 may be the entire UE (e.g., see Figure 3 of 350).

[0097] In one configuration, an apparatus 602 / 602' for wireless communication includes: means for receiving an indication from a base station that a feature of a MAC-CE update of a path loss reference signal is enabled, e.g., as described in conjunction with 506; means for receiving a MAC-CE to update a path loss reference signal, e.g., as described in conjunction with 508; and means for determining a path loss reference signal based on the MAC-CE and the indication that the MAC-CE update of the path loss reference signal is enabled, e.g., as described in conjunction with 510. The apparatus may further include means for receiving a configuration of a default SRI in an RRC configuration, e.g., as described in conjunction with 504. The apparatus may further include means for receiving a configuration of a set of one or more path loss reference signals for a UE in an RRC configuration, wherein the MAC-CE activates at least one of the one or more path loss reference signals, e.g., as described in conjunction with 502. The apparatus may further include means for estimating a downlink path loss based on the determined path loss reference signal, e.g., as described in conjunction with 512. The device may further include means for determining a transmit power for an uplink signal based at least in part on the downlink path loss, e.g., as described in conjunction with 514. The device may include means for transmitting the uplink signal with the determined transmit power, e.g., as described in conjunction with 516. The aforementioned means may be one or more of the aforementioned components of the device 602 and / or the processing system 714 of the device 602' configured to perform the functions recited by the aforementioned means. As described above, the processing system 714 may include the TX processor 368, the RX processor 356, and the controller / processor 359. As such, in one configuration, the aforementioned means may be the TX processor 368, the RX processor 356, and the controller / processor 359 configured to perform the functions recited by the aforementioned means.

[0098] Figure 8 800 is a flow chart of a method of wireless communication. The method may be performed by a base station or a component of a base station (e.g., base station 102, 180, 310, 402; which may include memory 376 and which may be the entire base station 310 or a component of the base station 310, such as TX processor 316, RX processor 370, and / or controller / processor 375). The method may enable the base station to configure the UE for more accurate path loss measurements.

[0099] At 806, the base station transmits an indication to the UE that MAC-CE activation of the path loss reference signal is enabled. This transmission may be, for example, Fig. 9The indication may be performed by a transmission component 906 and / or an enabling component 908 of the device 902. The indication may be transmitted in RRC signaling. The indication may enable MAC-CE activation of a path loss reference signal for SRS. The indication may enable MAC-CE activation of a path loss reference signal update for PUSCH. The indication may enable MAC-CE activation of a path loss reference signal update for PUSCH scheduled by a DCI with an SRI field. The indication may enable MAC-CE activation of a path loss reference signal update for PUSCH scheduled based on a DCI format without an SRI field. The indication may indicate to the UE that the path loss reference signal is to be identified based on a default SRI. As illustrated in 804, the base station may transmit a configuration of a default SRI in an RRC configuration. The transmission may be, for example, by Fig. 9 The indication may be performed by the SRI component 920 of the device 902. The indication may be a single indication to enable MAC-CE update for path loss reference signals for SRS and PUSCH. The indication may include, for example, a combination of Figure 4 Any aspects described in indication 405 are included.

[0100] At 808, the base station transmits a MAC-CE activating a path loss reference signal (eg, activating a specific path loss reference signal). This transmission may be, for example, by Fig. 9 The MAC-CE component 910 of the device 902 may be executed by the transmission component 906 and / or the MAC-CE component 910. The MAC-CE may include a reference signal ID for a path loss reference signal activated by the MAC-CE. The MAC-CE may indicate or update a mapping between a path loss reference signal ID and an SRI for physical uplink shared channel power control. The MAC-CE update may include combining Figure 4 Aspects described in MAC-CE 407.

[0101] As illustrated at 802, the base station may transmit a configuration for the UE in an RRC configuration with a set of one or more path loss reference signals. Subsequently, based on the activation at 806, the MAC-CE may activate at least one of the one or more path loss reference signals. The transmission may be, for example, by Fig. 9 The path loss reference signal component 918 of the device 902 is performed.

[0102] As illustrated at 810, the base station may transmit one or more reference signals as path loss reference signals based on measurements to be made by the UE. The transmission may be, for example, Fig. 9 The transmission component 906 of the device 902 is executed.

[0103] in this way, Figure 8Each block in the foregoing flow chart may be performed by a component of a base station (such as RRC flag component 198) and the base station may include one or more of these components. These components may be one or more hardware components specifically configured to perform the process / algorithm, implemented by a processor configured to perform the process / algorithm, stored in a computer-readable medium for implementation by a processor, or some combination thereof.

[0104] Fig. 9 9 is a conceptual data flow diagram 900 illustrating data flow between different means / components in an example device 902. The device can be a base station or a component of a base station. The device 902 includes a receiving component 904 configured to receive uplink communications from a UE 950, and a transmitting component 906 configured to transmit downlink communications to the UE 950. The device 902 includes an enabling component 908 configured to transmit an indication to the UE that MAC-CE activation of a path loss reference signal is enabled, e.g., as described in conjunction with Figure 8 The device 902 includes a MAC-CE component 910 configured to transmit a MAC-CE activating a path loss reference signal, for example, as described in conjunction with Figure 8 The device 902 may include a path loss reference signal component 918 configured to transmit a set of one or more path loss reference signals for the UE in an RRC configuration, for example, as described in conjunction with Figure 8 Device 902 may include an SRI component 920 configured to transmit a configuration of a default SRI, for example, as described in conjunction with Figure 8 As described in 804.

[0105] The device may include executing Figure 8 The various blocks of the algorithms in the aforementioned flow charts and the additional components of various aspects performed by the base station 402. Thus, Figure 8 Each block in the foregoing flow chart and various aspects performed by the base station 402 may be performed by a component and the device may include one or more of these components. These components may be one or more hardware components specifically configured to perform the process / algorithm, implemented by a processor configured to perform the process / algorithm, stored in a computer-readable medium for implementation by a processor, or some combination thereof.

[0106] Fig.101 is a diagram 1000 illustrating an example of a hardware implementation of a device 902' employing a processing system 1014. The processing system 1014 may be implemented with a bus architecture generally represented by a bus 1024. The bus 1024 may include any number of interconnecting buses and bridges, depending on the specific application and overall design constraints of the processing system 1014. The bus 1024 links various circuits together, including one or more processors and / or hardware components (represented by the processor 1004, components 904, 906, 908, 910, 918, 920, and computer readable medium / memory 1006). The bus 1024 may also link various other circuits, such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art and therefore will not be described further.

[0107] The processing system 1014 may be coupled to the transceiver 1010. The transceiver 1010 is coupled to one or more antennas 1020. The transceiver 1010 provides a means for communicating with various other devices over a transmission medium. The transceiver 1010 receives signals from the one or more antennas 1020, extracts information from the received signals, and provides the extracted information to the processing system 1014 (specifically, the receiving component 904). In addition, the transceiver 1010 receives information from the processing system 1014 (specifically, the transmitting component 906) and generates signals to be applied to the one or more antennas 1020 based on the received information. The processing system 1014 includes a processor 1004 coupled to a computer-readable medium / memory 1006. The processor 1004 is responsible for general processing, including the execution of software stored on the computer-readable medium / memory 1006. The software, when executed by the processor 1004, causes the processing system 1014 to perform the various functions described above for any particular device. The computer-readable medium / memory 1006 may also be used to store data manipulated by the processor 1004 when executing software. The processing system 1014 further includes at least one of the components 904, 906, 908, 910, 918, 920. These components may be software components running in the processor 1004, software components resident / stored in the computer-readable medium / memory 1006, one or more hardware components coupled to the processor 1004, or some combination thereof. The processing system 1014 may be a component of the base station 310 and may include the memory 376 and / or at least one of the following: the TX processor 316, the RX processor 370, and the controller / processor 375. Alternatively, the processing system 1014 may be the entire base station (e.g., see Figure 3 310).

[0108] In one configuration, the apparatus 902 / 902' for wireless communication includes: means for transmitting an indication to a UE that a feature of a MAC-CE update of a path loss reference signal is enabled, e.g., as described in conjunction with 806; and means for transmitting a MAC-CE for updating a path loss reference signal, e.g., as described in conjunction with 808. The apparatus may further include means for transmitting a configuration of a default SRI in an RRC configuration, e.g., as described in conjunction with 804. The apparatus may further include means for transmitting a configuration of a set of one or more path loss reference signals for the UE in an RRC configuration, wherein the MAC-CE activates at least one of the one or more path loss reference signals, e.g., as described in conjunction with 802. The aforementioned means may be one or more of the aforementioned components of the apparatus 902 and / or the processing system 1014 of the apparatus 1002' configured to perform the functions recited by the aforementioned means. As described above, the processing system 1014 may include the TX processor 316, the RX processor 370, and / or the controller / processor 375. As such, in one configuration, the aforementioned means may be the TX processor 316, the RX processor 370, and / or the controller / processor 375 configured to perform the functions recited by the aforementioned means.

[0109] It should be understood that the specific order or hierarchy of each box in the disclosed process / flowchart is an illustration of an example approach. It should be understood that the specific order or hierarchy of each box in these process / flowcharts can be rearranged based on design preferences. In addition, some boxes can be combined or omitted. The attached method claims present the elements of various boxes in an exemplary order and are not meant to be limited to the specific order or hierarchy presented.

[0110] The following examples are merely illustrative, and aspects thereof may be combined with aspects of other embodiments or teachings described herein without limitation.

[0111] Example 1 is a method for performing wireless communications at a user equipment (UE), comprising: receiving an indication from a base station that MAC-CE activation of a path loss reference signal is enabled; receiving a MAC-CE that activates the path loss reference signal; determining the path loss reference signal based on the MAC-CE and an indication that the MAC-CE activation indicating the path loss reference signal is enabled; and estimating a downlink path loss based on the path loss reference signal activated by the MAC-CE.

[0112] In Example 2, the method of Example 1 further includes using the path loss reference signal for SRS.

[0113] In Example 3, the method of Example 1 or Example 2 further includes using the path loss reference signal for a PUSCH.

[0114] In Example 4, the method of any one of Examples 1-3 further includes using the path loss reference signal for a PUSCH scheduled by a DCI having a SRI field.

[0115] In Example 5, the method of any one of Examples 1-4 further includes using the path loss reference signal for a PUSCH scheduled based on a DCI format without an SRI field.

[0116] In Example 6, the method of any one of Examples 1-5 further includes indicating, to the UE, that the path loss reference signal is to be identified based on a default SRI.

[0117] In Example 7, the method of any one of Examples 1-6 further includes receiving a configuration of the default SRI in an RRC configuration.

[0118] In Example 8, the method of any one of Examples 1-7 further includes the indication comprising a single indication to enable MAC-CE activation for path loss reference signals for SRS and PUSCH.

[0119] In Example 9, the method of any one of Examples 1-8 further includes the indication being received in RRC signaling.

[0120] In Example 10, the method of any one of Examples 1-9 further includes the MAC-CE including a reference signal ID for the path loss reference signal activated by the MAC-CE.

[0121] In Example 11, the method of any one of Examples 1-10 further includes the MAC-CE indicating a mapping between a path loss reference signal ID and a SRI for physical uplink shared channel power control.

[0122] In Example 12, the method of any one of Examples 1-11 further includes receiving a configuration of one or more path loss reference signals for the UE in an RRC configuration, wherein the MAC-CE activates at least one of the one or more path loss reference signals.

[0123] In Example 13, the method of any one of Examples 1-12 further includes determining a transmit power for an uplink signal based at least in part on the downlink path loss.

[0124] Example 14 is a device comprising one or more processors and one or more memories in electronic communication with the one or more processors, the one or more memories storing instructions executable by the one or more processors to cause the device to implement a method as in any of Examples 1-13.

[0125] Example 15 is a system or apparatus comprising means for implementing a method as in any one of Examples 1-13 or implementing an apparatus as in any one of Examples 1-13.

[0126] Example 16 is a non-transitory computer-readable medium storing instructions executable by one or more processors to cause the one or more processors to implement the method as in any of Examples 1-13.

[0127] Example 17 is a method for performing wireless communications at a base station, comprising: transmitting an indication to notify a UE that MAC-CE activation of a path loss reference signal is enabled; and transmitting a MAC-CE that activates the path loss reference signal based on the indication that the MAC-CE activation of the path loss reference signal is enabled.

[0128] In Example 18, the method of Example 17 further includes using the path loss reference signal for SRS.

[0129] In Example 19, the method of Example 17 or Example 18 further includes using the path loss reference signal for a PUSCH.

[0130] In Example 20, the method of any one of Examples 17-19 further includes using the path loss reference signal for a PUSCH scheduled by a DCI having a SRI field.

[0131] In Example 21, the method of any one of Examples 17-20 further includes using the path loss reference signal for a PUSCH scheduled based on a DCI format without an SRI field.

[0132] In Example 22, the method of any one of Examples 17-21 further includes indicating, to the UE, that the path loss reference signal is to be identified based on a default SRI.

[0133] In Example 23, the method of any one of Examples 17-22 further includes configuring the default SRI in the RRC configuration.

[0134] In Example 24, the method of any one of Examples 17-23 further includes the indication comprising a single indication enabling MAC-CE activation for the path loss reference signal for SRS and PUSCH.

[0135] In Example 25, the method of any one of Examples 17-24 further includes the indication being transmitted in RRC signaling.

[0136] In Example 26, the method of any one of Examples 17-25 further includes the reference signal ID for the path loss reference signal activated by the MAC-CE.

[0137] In Example 27, the method of any one of Examples 17-26 further includes the MAC-CE indicating a mapping between a path loss reference signal ID and a SRI for physical uplink shared channel power control.

[0138] In Example 28, the method of any one of Examples 17-27 further includes configuring one or more path loss reference signals for the UE in an RRC configuration, wherein the MAC-CE activates at least one of the one or more path loss reference signals.

[0139] Example 29 is a device comprising one or more processors and one or more memories in electronic communication with the one or more processors, the one or more memories storing instructions executable by the one or more processors to cause the device to implement a method as in any of Examples 17-28.

[0140] Example 30 is a system or apparatus comprising means for implementing a method as in any of Examples 17-28 or implementing an apparatus as in any of Examples 1-11.

[0141] Example 31 is a non-transitory computer-readable medium storing instructions executable by one or more processors to cause the one or more processors to implement the method as in any of Examples 17-28.

[0142] The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be easily understood by those skilled in the art, and the universal principles defined in this article can be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown in this article, but should be granted the full scope consistent with the claims in language, wherein the singular reference of the elements is not intended to represent "there is and only one", but "one or more", unless otherwise stated. The wording "exemplary" is used in this article to represent "used as an example, instance, or explanation". Any aspect described as "exemplary" herein does not have to be interpreted as being superior to or superior to other aspects. Unless otherwise stated, the term "some / certain" refers to one or more. Combinations such as "at least one of A, B or C", "one or more of A, B or C", "at least one of A, B and C", "one or more of A, B and C" and "A, B, C or any combination thereof" include any combination of A, B and / or C, and may include multiple A, multiple B or multiple C. Specifically, combinations such as "at least one of A, B, or C," "one or more of A, B, or C," "at least one of A, B, and C," "one or more of A, B, and C," and "A, B, C, or any combination thereof" may be A only, B only, C only, A and B, A and C, B and C, or A and B and C, wherein any such combination may include one or more members of A, B, or C. All structural and functional equivalents of the elements of the various aspects described throughout this disclosure that are currently or hereafter known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be covered by the claims. In addition, nothing disclosed herein is intended to be dedicated to the public, regardless of whether such disclosure is explicitly stated in the claims. The terms "module," "mechanism," "element," "device," and the like may not be a substitute for the term "means." Thus, no claim element should be interpreted as a means-plus-function unless the element is explicitly stated using the phrase "means for..."

Claims

1. A method for wireless communication at a user equipment UE, comprising: receiving an indication that medium access control-control element MAC-CE activation of a path loss reference signal is enabled from the base station in radio resource control RRC signaling; receiving a MAC-CE for activating the path loss reference signal; determining the path loss reference signal based on the MAC-CE and an indication indicating that activation of the MAC-CE for the path loss reference signal is enabled; as well as A downlink path loss is estimated based on the path loss reference signal activated by the MAC-CE. 2 . The method of claim 1 , wherein the path loss reference signal is used for a sounding reference signal (SRS).

3. The method of claim 1, wherein the path loss reference signal is used for a physical uplink shared channel (PUSCH).

4. The method of claim 3, wherein the path loss reference signal is used for the PUSCH scheduled by downlink control information (DCI) having a sounding reference signal resource indicator (SRI) field.

5. The method of claim 3, wherein the path loss reference signal is used for the PUSCH scheduled based on a downlink control information (DCI) format without a sounding reference signal resource indicator (SRI) field. The method of claim 5 , wherein the path loss reference signal is based on a default path loss reference signal.

7. The method of claim 6, further comprising: The configuration of the default path loss reference signal is received in an RRC configuration.

8. The method of claim 1, wherein the indication comprises a single indication to enable the MAC-CE activation for the path loss reference signal for a sounding reference signal (SRS) and a physical uplink shared channel (PUSCH).

9. The method of claim 1, wherein the MAC-CE includes a reference signal identifier (ID) for the path loss reference signal activated by the MAC-CE.

10. The method of claim 1, wherein the MAC-CE indicates a mapping between a path loss reference signal identifier (ID) and a sounding reference signal resource indicator (SRI) for physical uplink shared channel power control.

11. The method of claim 1, further comprising: A configuration of one or more path loss reference signals for the UE is received in an RRC configuration, wherein the MAC-CE activates at least one of the one or more path loss reference signals.

12. The method of claim 1, further comprising: A transmit power for an uplink signal is determined based at least in part on the downlink path loss.

13. The method of claim 12, wherein the number of one or more path loss reference signals configured for the UE in the RRC configuration exceeds 4.

14. An apparatus for wireless communication at a user equipment UE, comprising: Memory; as well as at least one processor coupled to the memory, the memory and the at least one processor being configured to: receiving an indication that medium access control-control element MAC-CE activation of a path loss reference signal is enabled from the base station in radio resource control RRC signaling; receiving a MAC-CE for activating the path loss reference signal; determining the path loss reference signal based on the MAC-CE and an indication indicating that activation of the MAC-CE for the path loss reference signal is enabled; as well as A downlink path loss is estimated based on the path loss reference signal activated by the MAC-CE.

15. The apparatus of claim 14, wherein the at least one processor is further configured to: A configuration of one or more path loss reference signals for the UE is received in an RRC configuration, wherein the MAC-CE activates at least one of the one or more path loss reference signals. The apparatus of claim 14 , wherein the path loss reference signal is used for a sounding reference signal (SRS).

17. The apparatus of claim 14, wherein the path loss reference signal is used for a physical uplink shared channel (PUSCH).

18. The apparatus of claim 17, wherein the path loss reference signal is used for the PUSCH scheduled based on a downlink control information (DCI) format without a sounding reference signal resource indicator (SRI) field.

19. The apparatus of claim 18, wherein the path loss reference signal is based on a default path loss reference signal.

20. The apparatus of claim 14, wherein the indication comprises a single indication to enable the MAC-CE activation for the path loss reference signal for a sounding reference signal (SRS) and a physical uplink shared channel (PUSCH).

21. The apparatus of claim 14, wherein the MAC-CE includes a reference signal identifier (ID) for the path loss reference signal activated by the MAC-CE.

22. The apparatus of claim 14, wherein the MAC-CE indicates a mapping between a path loss reference signal identifier (ID) and a sounding reference signal resource indicator (SRI) for physical uplink shared channel power control.

23. A method for wireless communication at a base station, comprising: transmitting, in radio resource control RRC signaling, to the user equipment UE, an indication that medium access control-control element MAC-CE activation of a path loss reference signal is enabled; A MAC-CE activating the path loss reference signal is transmitted based on an indication indicating that the MAC-CE activation of the path loss reference signal is enabled. The method of claim 23 , wherein the path loss reference signal is used for a sounding reference signal (SRS).

25. The method of claim 23, wherein the path loss reference signal is used for a physical uplink shared channel (PUSCH).

26. The method of claim 25, wherein the path loss reference signal is used for the PUSCH scheduled by downlink control information (DCI) having a sounding reference signal resource indicator (SRI) field.

27. The method of claim 25, wherein the path loss reference signal is used for the PUSCH scheduled based on a downlink control information (DCI) format without a sounding reference signal resource indicator (SRI) field.

28. The method of claim 27, wherein the indication indicates to the UE that the path loss reference signal is identified based on a default path loss reference signal.

29. The method of claim 28, further comprising: The default path loss reference signal is configured in the RRC configuration.

30. The method of claim 23, wherein the indication comprises a single indication enabling MAC-CE activation for the path loss reference signal for a sounding reference signal (SRS) and a physical uplink shared channel (PUSCH).

31. The method of claim 23, wherein the MAC-CE includes a reference signal identifier (ID) for the path loss reference signal activated by the MAC-CE.

32. The method of claim 23, wherein the MAC-CE indicates a mapping between a path loss reference signal identifier (ID) and a sounding reference signal resource indicator (SRI) for physical uplink shared channel power control.

33. The method of claim 23, further comprising: One or more path loss reference signals for the UE are configured in an RRC configuration, wherein the MAC-CE activates at least one of the one or more path loss reference signals.

34. An apparatus for wireless communication at a base station, comprising: Memory; as well as at least one processor coupled to the memory, the memory and the at least one processor being configured to: transmitting, in radio resource control RRC signaling, to the user equipment UE, an indication that medium access control-control element MAC-CE activation of a path loss reference signal is enabled; A MAC-CE activating the path loss reference signal is transmitted based on an indication indicating that the MAC-CE activation of the path loss reference signal is enabled.

35. The apparatus of claim 34, wherein the at least one processor is further configured to: One or more path loss reference signals for the UE are configured in an RRC configuration, wherein the MAC-CE activates at least one of the one or more path loss reference signals.

36. A non-transitory computer readable medium storing computer executable code which, when executed by at least one processor, causes the at least one processor to: receiving an indication that medium access control-control element MAC-CE activation of a path loss reference signal is enabled from the base station in radio resource control RRC signaling; receiving a MAC-CE for activating the path loss reference signal; determining the path loss reference signal based on the MAC-CE and an indication indicating that activation of the MAC-CE for the path loss reference signal is enabled; as well as A downlink path loss is estimated based on the path loss reference signal activated by the MAC-CE.

37. The non-transitory computer readable medium of claim 36, wherein the path loss reference signal is used for a sounding reference signal (SRS).

38. The non-transitory computer readable medium of claim 36, wherein the path loss reference signal is for a physical uplink shared channel (PUSCH).

39. The non-transitory computer-readable medium of claim 38, wherein the path loss reference signal is used for the PUSCH scheduled based on a downlink control information (DCI) format without a sounding reference signal resource indicator (SRI) field.

40. The non-transitory computer readable medium of claim 39, wherein the path loss reference signal is based on a default path loss reference signal.

41. The non-transitory computer readable medium of claim 36, wherein the indication comprises a single indication to enable the MAC-CE activation for the path loss reference signal for a sounding reference signal (SRS) and a physical uplink shared channel (PUSCH).

42. The non-transitory computer-readable medium of claim 36, wherein the MAC-CE includes a reference signal identifier (ID) for the path loss reference signal activated by the MAC-CE.

43. The non-transitory computer-readable medium of claim 36, wherein the MAC-CE indicates a mapping between a path loss reference signal identifier (ID) and a sounding reference signal resource indicator (SRI) for physical uplink shared channel power control.

44. The non-transitory computer readable medium of claim 36, wherein the code, when executed by at least one processor, further causes the at least one processor to: A configuration of one or more path loss reference signals for a user equipment UE is received in an RRC configuration, wherein the MAC-CE activates at least one of the one or more path loss reference signals.

45. A device for wireless communication, comprising: means for receiving an indication in radio resource control, RRC signalling, from a base station that medium access control - control element, MAC-CE activation of a path loss reference signal is enabled; means for receiving a MAC-CE activating said path loss reference signal; means for determining the path loss reference signal based on the MAC-CE and an indication indicating that activation of the MAC-CE for the path loss reference signal is enabled; as well as means for estimating a downlink path loss based on the path loss reference signal activated by the MAC-CE.

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