EP4696063A1 - Reporting power headroom for dynamic waveform switching - Google Patents

Abstract

Example methods, systems, and techniques are disclosed for a user equipment (UE) to report power headroom for dynamic waveform switching. As a base station (BS) may indicate a specific waveform to a UE to transmit a scheduled uplink (UL) transmission, the base station needs to know when and what specific waveform to have the UE switch to. To help the BS better evaluate the waveform switching timing, the UE may send assistance information to the BS regarding the power headroom of a target waveform (a waveform not indicated in the downlink control information (DCI)). The present disclosure provides examples of such assistance information (e.g., medium access control (MAC) control element (CE) including UE determined power headroom report (PHR)).

Description

REPORTING POWER HEADROOM FOR DYNAMIC WAVEFORM SWITCHING CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit of and priority to the United States Provisional Application Serial No. 63/502,249, titled “REPORTING POWER HEADROOM FOR DYNAMIC WAVEFORM SWITCHING,” filed on May 15, 2023, the disclosure of which is incorporated herein by reference in their entirety. FIELD [0002] This disclosure relates to wireless communications and, more particularly, to power headroom report (PHR). BACKGROUND [0003] In the fifth generation (5G) new radio (NR) standards, the third Generation Partnership Project (3GPP) may enhance NR coverage by dynamically switching between different waveforms that have different peak-to-average power ratios (PAPRs) and therefore provide different power headrooms/levels for transmission. [0004] In the legacy specifications, the default waveform is cyclic prefix orthogonal frequency division multiplexing (CP-OFDM) waveform. The base station may enable the transform precoder of a user equipment (UE) to transmit uplink (UL) transmissions with Discrete Fourier Transform spread Orthogonal Frequency Division Multiplexing (DFT-s- OFDM) waveform. Comparing to CP-OFDM, a signal modulated in DFT-s-OFDM shows lower peak-to-average power ratio (PAPR) and cubic metric (CM). With lower PAPR and CM, the UE may deliver higher transmission power to uplink transmissions, thereby increase the UL coverage. The base station changes the UL transmission waveforms through radio resource control (RRC) signaling. However, the RRC signaling imposes a large barrier (e.g., latency, overhead, etc.) for the waveform switching, thereby decreases the performance especially for cell edge UE(s). [0005] The 3GPP introduces dynamic waveform switching (DWS), in which a base station may use a 1-bit field in the UL scheduling downlink control information (DCI) format to indicate a specific waveform to a UE to transmit the scheduled UL transmission (e.g., via physical uplink shared channel (PUSCH)). The base station, however, does not necessarily know when and what specific waveform to have the UE switch to (e.g., the current specification limits power headroom computation to the actually scheduled uplink in a waveform different from the waveform to be switched to). BRIEF DESCRIPTION OF THE DRAWINGS [0006] Fig.1A is a block diagram of an example wireless communication system in which a radio access network (RAN) and/or a UE implement the techniques of this disclosure for managing PHR of dynamic waveform switching. [0007] Fig.1B is a block diagram of an example base station including a central unit (CU) and a distributed unit (DU) that may operate in the system of Fig.1A. [0008] Fig.2A is a block diagram of an example protocol stack according to which the UE of Figs.1A-1B may communicate with base stations. [0009] Fig.2B is a block diagram of an example protocol stack according to which the UE of Figs.1A-1B may communicate with a DU and a CU of a base station. [0010] Fig.3A, 3B, 3C, and 3D are signaling diagrams of examples scenarios 300A, 300B, 300C, and 300D, respectively, where a UE reports a PHR for the target waveform based on a reference format based on various methods. [0011] Fig.4 is a messaging diagram of an example scenario 400, where a UE sends a PHR for a waveform on a PUSCH, only if the PUSCH is scheduled with a FDRA type that is applicable to the waveform. [0012] Figs.5A, 5B, and 5C are example MAC CE formats for single cell communication, where a PHR may include plural PH(s) of different waveforms or single PH with a waveform indicator. [0013] Figs.6A, 6B, and 6C are example MAC CE formats for multi-cell operation (e.g., carrier aggregation (CA), dual connectivity (DC)). [0014] Fig.7 is a flow diagram of an example method, where a UE obtains power headroom for a waveform according to the scheduled resource allocation types and the reference format. [0015] Fig.8A and 8B are flow diagrams of example methods, where a UE obtains multiple PHs and determines to include the PH(s) in the same or different PHR. [0016] Fig.9A and 9B are flow diagram of example methods, where a UE determines to enable the enhanced power headroom reporting for waveform(s) based on the power headroom configuration or dynamic waveform switching configuration. [0017] Fig.10 is a flow diagram of example methods, where a base station determines whether a PH receives from a UE is based on the scheduling DCI or a reference format [0018] Fig.11A and 11B are flow diagram of example methods, where a base station receives one or multiple PHR regarding multiple waveforms, and determines scheduling parameters accordingly. [0019] Fig.12 is flow diagram of an example method, where a base station enables a UE to send enhanced power headroom report according to the UE capability. [0020] Fig.13 illustrates an example flowchart of a method performed by a UE, in accordance with aspects of this disclosure. [0021] Fig.14 illustrates an example flowchart of a method performed by a network entity, in accordance with aspects of this disclosure. [0022] Fig.15 is a diagram illustrating a hardware implementation for an example UE apparatus. [0023] Fig.16 is a diagram illustrating a hardware implementation for one or more example network entities. [0024] Like numerals indicate like elements. DETAILED DESCRIPTION [0025] The present disclosure provides methods, systems, and techniques for reporting power headroom for dynamic waveform switching. As a base station (BS) may indicate a specific waveform to a user equipment (UE) to transmit a scheduled uplink (UL) transmission, the base station needs to know when and what specific waveform to have the UE switch to. To help the BS better evaluate the waveform switching timing, the UE may send assistance information to the BS regarding the power headroom of a target waveform (a waveform not indicated in the downlink control information (DCI)). The present disclosure provides examples of such assistance information (e.g., medium access control (MAC) control element (CE) including UE determined power headroom report (PHR)). [0026] In the current specification, a UE may be configured to transmit a PHR that includes the maximum available transmission power (P_CMAX,f,c) and the power headroom (PH) that the UE generates based on an actual transmitted transmission (e.g., PUSCH, SRS) or a specified reference format (e.g., see section 7.7 in 3GPP technical specification (TS) 38.213). According to the current specification, the UE does not report the PHR based on a target waveform that is not currently scheduled. As such, the base station may not be able to determine whether to schedule subsequent transmissions with the target waveform. [0027] Furthermore, even though a base station may schedule a PUSCH transmission in CP-OFDM with frequency domain resource allocation (FDRA) type-0, type-1, and dynamic switching between type-0 and type-1 (see, e.g., 3GPP TS 38.214, sections 6.1.2.2.1 and 6.1.2.2.2), the base station may only schedule a PUSCH transmission in DFT-s-OFDM (e.g., the target waveform) with FDRA type-1. Therefore, the current specification does not provide how to determine the PH of the target waveform (e.g., DFT-s-OFDM) when the actual transmitted PUSCH is scheduled in CP-OFDM with FDRA type-0. The present disclosure provides methods and techniques for the UE to provide PHR for the target waveform to resolve these issues. [0028] The techniques of this disclosure introduce a mechanism for a UE to report PH of one or multiple waveforms, when the UE is scheduled by a base station to transmit a PUSCH transmission according to the waveform (e.g., CP-OFDM or DFT-s-OFDM) indicated by the scheduling DCI. For each waveform, the UE may apply different levels of power reduction to mitigate signal distortion due to the power amplifier (PA) limitation or to comply with radio regulations such as maximum permitted exposure (MPE) and specific absorption rate (SAR). The level of power reduction is based on UE capability. UE may reveal the power reduction level to the base station by the P_cmax field in a PHR. This information assists the base station to conduct power control procedures and determine a UL transmission waveform in terms of throughput or coverage perspective. [0029] Fig.1A depicts an example wireless communication system 100 in which communication devices may implement the techniques above, with various examples described below. The wireless communication system 100 includes a UE 102, a base station 104 (e.g., a source BS 104, or a similar network entity), a base station 106 (operating in the handover scenarios discussed below as the target BS 106), and a core network (CN) 110. The UE 102 initially connects to the base station 104. The base stations 104 and 106 may operate in a radio access network (RAN) 105 connected to the CN 110. The CN 110 may be implemented as an evolved packet core (EPC) 111 or a fifth generation (5G) core (5GC), 1540, for example. [0030] Among other components, the EPC 111 may include a Serving Gateway (SGW) 112, a Mobility Management Entity (MME) 114, and a Packet Data Network Gateway (PGW) 116. Generally speaking, the SGW 112 is configured to transfer user-plane packets related to audio calls, video calls, Internet traffic, etc., and the MME 114 is configured to manage authentication, registration, paging, and other related functions. The PGW 116 provides connectivity from the UE to external packet data networks including Internet network and/or an Internet Protocol (IP) Multimedia Subsystem (IMS) network by being the point of exit and entry of traffic for the UE. The 5GC 1540 includes a User Plane Function (UPF) 162, an Access and Mobility Management Function (AMF) 164, and/or Session Management Function (SMF) 166. Generally speaking, the UPF 162 is configured to transfer user-plane packets related to audio calls, video calls, Internet traffic, etc., the AMF 164 is configured to manage authentication, registration, paging, and other related functions, and the SMF 166 is configured to manage PDU sessions. [0031] As illustrated in Fig.1A, the base station 104 supports a cell 124, and the base station 106 supports a cell 126. The baes statin 104 may additionally supports a cell 125. The cells 124 and 125 may partially overlap, so that while communicating with the UE 102 via the cell 124, the base station 104 hands over the UE 102 to the cell 125. The cells 124 and 126 may partially overlap, so that while communicating with the UE 102 via the cell 124, the base station 104 hands over the UE 102 to the base station 106 operating as a target base station. To directly exchange messages during handover scenarios discussed below, the base station 104 and the base station 106 may support an X2 or Xn interface. In general, the CN 110 may connect to any suitable number of base stations supporting NR cells and/or EUTRA cells. [0032] In general, the wireless communication network 100 may include any suitable number of base stations supporting NR cells and/or EUTRA cells. More particularly, the EPC 111 or the 5GC 1540 may be connected to any suitable number of base stations supporting NR cells and/or EUTRA cells. Although the examples below refer specifically to specific CN types (EPC, 5GC) and RAT types (5G NR and EUTRA), in general the techniques of this disclosure also may apply to other suitable radio access and/or core network technologies such as sixth generation (6G) radio access and/or 6G core network. [0033] With continued reference to Fig.1A, the base station 104 is equipped with processing hardware 130 that may include one or more general-purpose processors (e.g., CPUs) and a non-transitory computer-readable memory storing instructions that the one or more general-purpose processors execute. Additionally, or alternatively, the processing hardware 130 may include special-purpose processing units. The processing hardware 130 may include a PHY controller 132 configured to transmit data and control signal on physical downlink (DL) channels and DL reference signals with one or more user devices (e.g., UE 102) via one or more cells and/or one or more TRPs. The PHY controller 132 is also configured to receive data and control signal on physical uplink (UL) channels and/or UL reference signals with the one or more user devices via one or more cells and/or one or more TRPs. The PHY controller 132 may be configured to manage dynamic waveform switching for one or more UL transmissions from one or more user devices. The processing hardware 130 in an example implementation includes a MAC controller 134 configured to perform MAC functions with one or more user devices. The MAC functions include a random access (RA) procedure, managing UL timing advance for the one or more user devices, and/or communicating UL/DL MAC PDUs with the one or more user devices. The MAC controller 134 may be configured to manage one or more devices to transmit PHRs. The processing hardware 130 may further include a RLC controller (not show in Fig.1A) configured to perform RLC functions with one or more user devices. The processing hardware 130 may further include a PDCP controller (not show in Fig.1A) configured to perform PDCP functions with one or more user devices. The processing hardware 130 may further include an RRC controller 136 to implement procedures and messaging at the RRC sublayer of the protocol communication stack. For example, the RRC controller 132 may be configured to support RRC messaging associated with UL dynamic waveform switching, power headroom reporting, resource configuration, measurement configuration procedure and reconfiguration procedure and/or handover procedures. The base station 106 may include processing hardware 140 that is similar to processing hardware 130. In particular, components 142, 144, and 146 may be similar to the components 132, 134, and 136, respectively. [0034] The UE 102 is equipped with processing hardware 150 that may include one or more general-purpose processors such as CPUs and non-transitory computer-readable memory storing machine-readable instructions executable on the one or more general- purpose processors, and/or special-purpose processing units. The PHY controller 152 is also configured to receive data and control signal on physical DL channels and/or DL reference signals with the base station 104 or 106 via one or more cells and/or one or more TRPs. The PHY controller 152 is also configured to transmit data and control signal on physical UL channels and/or UL reference signals with the base station 104 or 106 via one or more cells and/or one or more TRPs. The PHY controller 132 may also be configured to perform dynamic waveform switching for one or more UL transmissions. The processing hardware 150 in an example implementation includes a MAC controller 154 configured to perform MAC functions with base station 104 or 106. For example, the MAC functions include a random-access procedure, managing UL timing for communication with the base station 104 or 106, and communicating UL/DL MAC PDUs with the base station 104 or 106. The MAC controller 154 may also be configured to transmit PHRs. The processing hardware 150 may further include an RRC controller 156 to implement procedures and messaging at the RRC sublayer of the protocol communication stack. The processing hardware 150 may further include a RLC controller (not show in Fig.1A) configured to perform RLC functions with the base station 104 or 106. The processing hardware 150 may further include a PDCP controller (not show in Fig.1A) configured to perform PDCP functions with the base station 104 or 106. [0035] Fig.1B depicts an example, distributed or disaggregated implementation of any one or more of the base stations 104, 106. In this implementation, the base station 104, 106 includes a central unit (CU) 172 and one or more DUs 174. Each of the DU(s) may operate one or more cells. For example, the base station 104 includes a DU operating the cell 124 and/or cell 125. In another example, the base station 104 includes a DU 174A and a DU 174B that operate the cell 124 and the cell 125, respectively. The CU 172 includes processing hardware, such as one or more general-purpose processors (e.g., CPUs) and a computer- readable memory storing machine-readable instructions executable on the general-purpose processor(s), and/or special-purpose processing units. For example, the CU 172 may include an RRC controller such as RRC controller 136, 146. The CU 172 may a PDCP controller and/or a Service Data Adaptation Protocol (SDAP) controller. [0036] Each of the DUs 174 also includes processing hardware that may include one or more general-purpose processors (e.g., CPUs) and computer-readable memory storing machine-readable instructions executable on the one or more general-purpose processors, and/or special-purpose processing units. For example, the processing hardware may include a MAC controller (e.g., MAC controller 132, 142) configured to manage or control one or more MAC operations or procedures (e.g., a random access procedure), and/or a RLC controller configured to manage or control one or more RLC operations or procedures. The process hardware may also include a physical layer controller configured to manage or control one or more physical layer operations or procedures. [0037] In some implementations, the CU 172 may include a logical node CU-CP 172A that hosts the control plane part of the PDCP protocol of the CU 172. The CU 172 may also include logical node(s) CU-UP 172B that hosts the user plane part of the PDCP protocol and/or SDAP protocol of the CU 172. The CU-CP 172A may transmit control information (e.g., RRC messages, F1 application protocol messages), and the CU-UP 172B may transmit the data packets (e.g., SDAP PDUs or Internet Protocol packets). [0038] The CU-CP 172A may be connected to multiple CU-UP 172B through the E1 interface. The CU-CP 172A selects the appropriate CU-UP 172B for the requested services for the UE 102. In some implementations, a single CU-UP 172B may be connected to multiple CU-CP 172A through the E1 interface. The CU-CP 172A may be connected to one or more DU 174s through an F1-C or W1-C interface. The CU-UP 172B may be connected to one or more DU 174 through an F1-U or W1-U interface under the control of the same CU- CP 172A. In some implementations, one DU 174 may be connected to multiple CU-UP 172B under the control of the same CU-CP 172A. In such implementations, the connectivity between a CU-UP 172B and a DU 174 is established by the CU-CP 172A using Bearer Context Management functions. [0039] Fig.2A illustrates, in a simplified manner, an example protocol stack 200 according to which the UE 102 may communicate with an eNB/ng-eNB or a gNB (e.g., one or more of the base stations 104, 106). [0040] In the example stack 200, a physical layer (PHY) 202A of EUTRA provides transport channels to the EUTRA MAC sublayer 204A, which in turn provides logical channels to the EUTRA RLC sublayer 206A. The EUTRA RLC sublayer 206A in turn provides RLC channels to an EUTRA PDCP sublayer 208 and, in some cases, to an NR PDCP sublayer 210. Similarly, the NR PHY 202B provides transport channels to the NR MAC sublayer 204B, which in turn provides logical channels to the NR RLC sublayer 206B. The NR RLC sublayer 206B in turn provides data transfer services to the NR PDCP sublayer 210. The NR PDCP sublayer 210 in turn may provide data transfer services to Service Data Adaptation Protocol (SDAP) 212 or a radio resource control (RRC) sublayer (not shown in Fig.2A). The UE 102, in some implementations, supports both the EUTRA and the NR stack as shown in Fig.2A, to support handover between EUTRA and NR base stations and/or to support DC over EUTRA and NR interfaces. Further, as illustrated in Fig.2A, the UE 102 may support layering of NR PDCP 210 over EUTRA RLC 206A, and SDAP sublayer 212 over the NR PDCP sublayer 210. [0041] The EUTRA PDCP sublayer 208 and the NR PDCP sublayer 210 receive packets (e.g., from an Internet Protocol (IP) layer, layered directly or indirectly over the PDCP layer 208 or 210) that may be referred to as service data units (SDUs), and output packets (e.g., to the RLC layer 206A or 206B) that may be referred to as protocol data units (PDUs). Except where the difference between SDUs and PDUs is relevant, this disclosure for simplicity refers to both SDUs and PDUs as “packets.” [0042] On a control plane, the EUTRA PDCP sublayer 208 and the NR PDCP sublayer 210 may provide signaling radio bearers (SRBs) or RRC sublayer (not shown in Fig. 2A) to exchange RRC messages or non-access-stratum (NAS) messages, for example. On a user plane, the EUTRA PDCP sublayer 208 and the NR PDCP sublayer 210 may provide DRBs to support data exchange. Data exchanged on the NR PDCP sublayer 210 may be SDAP PDUs, Internet Protocol (IP) packets or Ethernet packets. [0043] Fig.2B illustrates, in a simplified manner, an example protocol stack 250 which the UE 102 may communicate with a DU (e.g., DU 174) and a CU (e.g., CU 172). The radio protocol stack 200 is functionally split as shown by the radio protocol stack 250 in Fig. 2B. The CU at any of the base stations 104 or 106 may hold all the control and upper layer functionalities (e.g., RRC 214, SDAP 212, NR PDCP 210), while the lower layer operations (e.g., NR RLC 206B, NR MAC 204B, and NR PHY 202B) are delegated to the DU. To support connection to a 5GC, NR PDCP 210 provides SRBs to RRC 214, and NR PDCP 210 provides DRBs to SDAP 212 and SRBs to RRC 214. [0044] Figs.3A-3D are signaling diagrams of example scenarios 300A-300D, in which a UE may generate a PH of a target waveform based on a reference format. Generally speaking, the similar events in Figs.3A-3D are labeled with similar reference numerals (e.g., event 308A is similar to events 308B and 308D, etc., event 309C is similar to event 309D, etc., and event 317C is similar to event 317D, etc.), with differences discussed below where appropriate. With the exception of the differences shown in the figures and discussed below, any of the alternative implementations discussed with respect to a particular event (e.g., for messaging and processing) may apply to events labeled with similar reference numbers in other figures. For example, the events may include at least the triggering events mentioned in 3GPP TS 38.321 section 5.4.6. and other similar triggering events. [0045] Referring first to an example scenario 300A illustrated in Fig.3A, a UE 102 communicates with a base station 104. Initially, the UE 102 may transmit 302 a first UE capability to the base station 104, indicating support of dynamic waveform switching and/or resource allocation types dynamic switching (e.g., dynamicSwitchRA-Type0-1-PUSCH). Alternatively, the base station 104 receives the first UE capability from the CN 110 or a base station 106 (not shown in Fig.3A). In some implementations, the first UE capability also indicates that the UE 102 supports power headroom reporting involving one or more waveforms in dynamic waveform switching. In other implementations, the UE 102 may transmit 302 to the base station 104 a second UE capability indicating that the UE 102 supports power headroom reporting involving one or more waveforms in dynamic waveform switching. [0046] Based on the first UE capability, the base station 104 sends 304, 306, 308A UL transmission configuration(s) (e.g., PUSCH-config and/or ConfiguredGrantConfig) to the UE 102. In some implementations, the base station 104 transmits 304, 306, 308A one or more RRC reconfiguration message including the UL transmission configuration(s) to the UE 102. In some implementations, the UL transmission configuration(s) includes a resource allocation configuration indicating the resource allocation type as dynamic switching (e.g., resourceAllocation = dynamicSwitch), and/or a dynamic switching configuration enabling the UE 102 to perform dynamic waveform switching (e.g., transformPrecoder = dynamicSwitch). To enable the UE 102 to send a PHR based on the waveform(s) for dynamic waveform switching, the base station 104 sends 308A a PHR configuration to the UE 102. In some implementations, the PHR configuration includes configuration parameters for power headroom reporting. In some implementations, the PHR configuration includes at least one first configuration configuring one or more triggering event(s) for power headroom reporting. The base station 104 may configure the triggering event(s) for sending a PHR involving a target waveform or without involving a target waveform. In some other implementations, the PHR configuration includes a second configuration to enable reporting a power headroom (PH) based on a (target) waveform for dynamic waveform switching. The base station 104 may configure the at least one first configuration and/or second configuration based on the first UE capability or second UE capability. If the base station 104 does not receive the first UE capability and/or the second UE capability, the base station 104 does not include the at least one first configuration and/or the second configuration in the PHR configuration. [0047] In other implementations, the triggering event(s) for sending a PHR involving a target waveform are predefined in 3GPP specifications. The UE 102 starts to detect the triggering event(s) and reports a power headroom (PH) based on a (target) waveform for dynamic waveform switching, upon receiving the resource allocation configuration and/or dynamic switching configuration. In such cases, the PHR configuration neither includes the first configuration(s) nor the second configuration. [0048] After (e.g., in response to) receiving the UL configuration(s), the UE 102 detects 310 a trigger event for reporting a PH involving a target waveform (e.g., a first waveform such as DFT-s-OFDM) occurs. After detecting 310 the trigger event occurs, the UE 102 receives 312 a 1^st DCI from the base station 104, and the 1^st DCI includes a resource allocation of a first type (e.g., type-0 frequency domain resource allocation (FDRA)) scheduling a 1^st PUSCH transmission and configures a second waveform (e.g., a CP-OFDM waveform). After (e.g., in response to) detecting occurrence of the trigger event and receiving the 1^st DCI, the UE 102 obtains (e.g., derives, calculates, or determines) a 1^st PH based on a reference format and the target waveform (e.g., DFT-s-OFDM) and generates 314 a 1^st PHR including 1^st PH. In addition, the UE 102 obtains a 1^st maximum available transmission power (P_CMAX,f,c), e.g., based on the reference format and the target waveform, and includes the 1^st PCMAX,f,c in the 1^st PHR. [0049] In some implementations, the reference format is predefined in a 3GPP specification (e.g., see 3GPP TS 38.213, section 7.7). In accordance with the 1^st DCI, the UE 102 generates the 1^st PUSCH transmission carrying the 1^st PHR and transmits and sends 316 the 1^st PUSCH transmission to the base station 104. In some implementations, the UE 102 generates a first MAC PDU including the 1^st PHR and a MAC subheader for the 1^st PHR and includes the MAC PDU in the 1^st PUSCH transmission. [0050] In some implementations, after (e.g., in response to) detecting occurrence of the trigger and receiving the 1^st DCI, the UE 102 obtains a 1^st additional PH based on the 1^st DCI and the second waveform and includes the 1^st additional PH in the 1^st PHR. In other alternative implementations, the UE 102 generates a 1^st additional PHR including the 1^st additional PH and includes the 1^st additional PHR in the 1^st PUSCH transmission. In such implementations, the UE 102 includes the 1^st additional PHR and a MAC subheader for the 1^st additional PHR in the first MAC PDU. In some implementations, the 1^st PHR and the additional 1^st PHR have different formats, and the MAC subheader for the 1^st additional PHR is different from the MAC subheader for the 1^st PHR. [0051] In some implementations, the reference format may be converted to the formula specified in the 3GPP TS 38.213, and the UE 102 obtains the 1^st PH based on the reference format and formulas as following: _{^^ ^^௧௬^^^,^,^,^ ൌ ^} ^{^} _^^ெ^^,^,^ ^{^} _^^ ^{^} _{െ ^ ^^ைುೆೄ^ಹ್,^,^} ^{^} _^^ ^{^} _{^ ^^^,^,^} ^{^} _^^ ^{^} _{∙ ^^ ^^^,^,^} ^{^} _^^ௗ ^{^} _{^ ^^^,^,^} ^{^} _{^^, ^^} ^{^} _^ where the UE 102 obtains ^^{^}^_^ெ^^,^,^^ ^^^ with the formulas (e.g., Formulas 2, 3 and 4) for obtaining ^^_^ெ^^,^,^^ ^^^ with Maximum Power Reduction (MPR), Additional Maximum Power Reduction (A-MPR), Power management Maximum Power Reduction (P-MPR), and ∆T_C that are set to 0 dB. PCMAX_L,f,c ≤ PCMAX,f,c ≤ PCMAX_H,f,c (Formula 2) PCMAX_L,f,c = MIN {PEMAX,c– ∆TC,c, (PPowerClass – ΔPPowerClass) – MAX(MAX(MPRc+∆MPRc, A-MPRc)+ ΔTIB,c + ∆TC,c + ∆TRxSRS, P-MPRc) } (Formula 3) } (Formula 4) _{After the UE 102 obtains ^^ ^^௧௬^^^,^,^,^ and ^} ^{^} _^^ெ^^,^,^ ^{^} _^^ ^{^} _{based on the formulas above, the UE} 102 ob the 1^st PH and 1^st P_CMAX,f,c from the ^^ and ^^{^}^_^ெ^^,^,^^ ^^ , e.g., based on mapping tables defined in 3GPP TS 38.133, respectively. [0052] In other implementations, the reference format is predefined in a 3GPP specification and the UE 102 obtains the 1^st PH based on the reference format and formulas as following: _{^^ ^^௧௬^^^,^,^,^ ൌ ^} ^{^} _^^ெ^^,^,^ ^{^} _^^ ^{^} _{െ ^ ^^ைುೆೄ^ಹ್,^,^} ^{^} _^^ ^{^} _{^ 10 ^^ ^^ ^^^^^2} ^ఓ _{∙ ^^ோ} ^{^} ^^{^} ,^ௌ ^^{^} ,_^ ^ு ,_{^ ^ ^^^^ ^ ^^^,^,^} ^{^} _^^ ^{^} _∙ 3GPP TS predefines the reference format as a resource allocation (e.g., type-1 FDRA) and a modulation and coding scheme (MCS), and thus the UE 102 obtains 10 ^^ ^^ ^^_^^^2^ఓ ∙ ^^_ோ ^{^} ^^{^} ,^ௌ ^^{^} ,_^ ^ு ,_^ ^ ^^^^ and ∆_்ி,^,^,^^ ^^^, based on the resource allocation and/or the MCS. In some implementations, the UE 102 obtains ^^{^}^_^ெ^^,^,^^ ^^^ for the target waveform in accordance with formulas 2, 3 and 4. In such cases, the UE 102 may determine MPR, A-MPR, and/or P-MPR (e.g., larger than zero), based on 3GPP TS 38.101 _{and the target waveform. After obtaining ^^ ^^௧௬^^^,^,^,^ and ^} ^{^} _^^ெ^^,^,^ ^{^} _^^ ^{^} _{based on the formulas} above, the UE 102 obtains the 1^st PH and 1^st P_CMAX,f,c from the ^^ ^^_{௧௬^^^,^,^,^} and ^^{^}^_^ெ^^,^,^^ ^^^, e.g., based on mapping tables defined in 3GPP TS 38.133, respectively. [0053] After transmitting 316 the 1^st PHR, the UE 102 detects 318 a trigger event for sending a PH involving the target waveform occurs. After detecting 318 the trigger event, the UE 102 receives 320 a 2^nd DCI from the base station 104, and the 2^nd DCI includes a resource allocation of a second type (e.g., type-1 FDRA) scheduling a 2^nd PUSCH transmission and configures a CP-OFDM waveform. In response to detecting the trigger event and receiving the 2^nd DCI, the UE 102 obtains a 2^nd PH based on the 2^nd DCI and the target waveform and generates 322 a 2^nd PHR including the 2^nd PH. [0054] In addition, the UE 102 obtains a maximum available transmission power (e.g., PCMAX,f,c) based on the reference format and the target waveform, and includes the PCMAX,f,c in the 1^st PHR. In accordance with the 2^nd DCI, the UE 102 generates a 2^nd PUSCH transmission including the 2^nd PH and sends 324 the 2^nd PUSCH transmission to the base station 104. In some implementations, the UE 102 generates a second MAC PDU including the 2^nd PHR and a MAC subheader for the 2^nd PHR and includes the MAC PDU in the 2^nd PUSCH transmission. The 2^nd PHR includes the 2^nd PH and the P_CMAX,f,c considering the power head room mapping and the mapping of PCMAX,f,c predefined in 3GPP TS 38.133. In some implementations, after (e.g., in response to) detecting the trigger event and receiving the 2^nd DCI, the UE 102 obtains a 2^nd additional PH based on the 2^nd DCI and the second waveform and includes the 2^nd additional PH in the 2^nd PHR. In other alternative implementations, the UE 102 generates a 2^nd additional PHR including the 2^nd additional PH and includes the 2^nd additional PHR in the 2^nd PUSCH transmission. In such implementations, the UE 102 includes the 2^nd additional PHR and a MAC subheader for the 2^nd additional PHR in the second MAC PDU. In some implementations, the 2^nd PHR and the additional 2^nd PHR have different formats, and the MAC subheader for the 2^nd additional PHR is different from the MAC subheader for the 2^nd PHR. [0055] In some implementations, the UE 102 obtains the 2^nd PH based on the resource allocation of the second type and/or the MCS configured in the 2^nd DCI. [0056] For example, the UE 102 obtains the 2^nd PH and/or 2^nd PCMAX,f,c, based on a formula as following: _{^^ ^^௧௬^^^,^,^,^ ൌ ^^^ெ^^,^,^^ ^^^ െ ^ ^^ைುೆೄ^ಹ್,^,^} ^{^} _^^ ^{^} _{^ 10 ^^ ^^ ^^^^^2} ^ఓ _{∙ ^^ோ} ^{^} ^^{^} ,^ௌ ^^{^} ,_^ ^ு ,_{^ ^ ^^^^ ^ ^^^,^,^} ^{^} _^^ ^{^} _∙ ^^ ^ ^^^ ^ ^^^^ 2, 3 and 4. In this example, the UE 102 may determine MPR, A-MPR, and/or P-MPR (e.g., larger than zero), based on 3GPP TS 38.101 and the target waveform. After obtaining ^^ ^^_{௧௬^^^,^,^,^} and ^^_^ெ^^,^,^^ ^^^ based on the formulas above, the UE 102 obtains the 2^nd PH and 2^nd P_CMAX,f,c from the ^^ ^^_{௧௬^^^,^,^,^} and ^^_^ெ^^,^,^^ ^^^, e.g., based on mapping tables defined in 3GPP specification 38.133, respectively. [0057] In some implementations, the UE 102 detects whether one or more triggering events irrelevant to waveform(s) in dynamic waveform switching occurs. For example, the trigger event is specified in 3GPP TS 38.321. If the UE 102 detects one, some or all of the triggering event(s) occurs, the UE 102 may transmit a PHR depending on a DCI, similar to transmission of the 1^st PHR or 2^nd PHR described above. In some implementations, the PHR configuration includes configuration parameters (e.g., phr-PeriodicTimer, phr-ProhibitTimer, phr-Tx-PowerFactorChange, mpe- mpe-Threshold) configuring the triggering event(s). [0058] In some implementations, the trigger events for reporting a PH involving waveform(s) in dynamic waveform switching include one or more of the following events: [0059] Event 1: A prohibit timer (e.g., phr-ProhibitTimer, dws-ProhibitTimer) expires or has expired, the measured path loss has lower than a configured path loss power threshold (e.g., dws-PathLossPowerThreshold) dB for at least one RS used as pathloss reference for one activated Serving Cell of any MAC entity of which the active DL BWP is not dormant BWP since the last transmission of a PHR in this MAC entity when the MAC entity has UL resources for new transmission; [0060] Event 2: A prohibit timer (e.g., phr-ProhibitTimer, dws-ProhibitTimer) expires or has expired, the indicated UL transmission waveform is CP-OFDM, and the path loss has higher than a configured path loss power threshold (e.g., dws- PathLossPowerThreshold) dB for at least one RS used as pathloss reference for one activated Serving Cell of any MAC entity of which the active DL BWP is not dormant BWP since the last transmission of a PHR in this MAC entity when the MAC entity has UL resources for new transmission; [0061] Event 3: A prohibit timer (e.g., phr-ProhibitTimer, dws-ProhibitTimer) expires or has expired, the indicated UL transmission waveform is DFT-s-OFDM, and the path loss has lower than a configured path loss power threshold (e.g., dws- PathLossPowerThreshold) dB for at least one RS used as pathloss reference for one activated Serving Cell of any MAC entity of which the active DL BWP is not dormant BWP since the last transmission of a PHR in this MAC entity when the MAC entity has UL resources for new transmission; [0062] Event 4: A prohibit timer (e.g., phr-ProhibitTimer, dws-ProhibitTimer) expires or has expired, the indicated UL transmission waveform is CP-OFDM, and the power headroom has lower than a configured power threshold (e.g., dws- PowerHeadroomThreshold) dB for at least one RS used as pathloss reference for one activated Serving Cell of any MAC entity of which the active DL BWP is not dormant BWP since the last transmission of a PHR in this MAC entity when the MAC entity has UL resources for new transmission; [0063] Event 5: A prohibit timer (e.g., phr-ProhibitTimer, dws-ProhibitTimer) expires or has expired, the indicated UL transmission waveform is DFT-s-OFDM, and the power headroom has higher than a configured power threshold (e.g., dws- PowerHeadroomThreshold) dB for at least one RS used as pathloss reference for one activated Serving Cell of any MAC entity of which the active DL BWP is not dormant BWP since the last transmission of a PHR in this MAC entity when the MAC entity has UL resources for new transmission; [0064] Event 6: A prohibit timer (e.g., phr-ProhibitTimer, dws-ProhibitTimer) expires or has expired and the power headroom ratio among waveforms (e.g., CP-OFDM and DFT-s-OFDM) has lower than, higher than or changes across a configured power threshold (e.g., dws-PowerHeadroomRatioThreshold) dB for at least one RS used as pathloss reference for one activated Serving Cell of any MAC entity of which the active DL BWP is not dormant BWP since the last transmission of a PHR in this MAC entity when the MAC entity has UL resources for new transmission; [0065] In some implementations, for a serving cell, each of the 1^st and 2^nd PHR includes 2 PHs, one of the PHs is calculated based on the waveform indicated for the PUSCH transmission (e.g., CP-OFDM) and another PH is calculated based on the waveform that is not indicated for the PUSCH transmission (e.g., DFT-s-OFDM). In some implementations, for a serving cell, each of the 1^st and 2^nd the PHR includes a single PH, one of the PHs is calculated based on the waveform indicated for the PUSCH transmission (e.g., CP-OFDM) and another PH is calculated based on the waveform that is not indicated for the PUSCH transmission (e.g., DFT-s-OFDM). [0066] Referring next to Fig.3B, a scenario 300B similar to the scenario 300A, except that the base station 104 indicates 308B, to the UE 102, a reference format in the PHR configuration. Then in the event 314, the UE 102 generates the 1^st PH according to the reference format indicated in the PHR configuration 308B and the target waveform. In some implementations, the PHR configuration includes a resource allocation (e.g., type-1 FDRA) and/or an MCS to configure reference format, thus the UE 102 obtains the 10 ^^ ^^ ^^_^^^2^ఓ ∙ ^_^ோ ^{^} ^^{^} ,^ௌ ^^{^} ,_^ ^ு ,_^ ^{^} _^^ ^{^} _{^ and ∆்ி,^,^,^} ^{^} _^^ ^{^} _{in formula 5 (or formula 6), based on the resource allocation} [0067] Referring next to Fig.3C, a scenario 300C similar to the scenario 300A. The differences between the scenarios 300A and 300C are described below. The base station 104 transmits 309C a 1^st PHR request requesting a PH involving a target waveform to the UE 102. In some implementations, the base station 104 includes a reference format in the 1^st PHR request. In some implementations, the reference format refers to the reference format and formula described in method 300A. For example, the 1^st PHR request includes a resource allocation (e.g., type-1 FDRA) and/or an MCS, thus the UE 102 may obtain 10 ^^ ^^ ^^_^^^2^ఓ ∙ ^^_ோ ^{^} ^^{^} ,^ௌ ^^{^} ,_^ ^ு ,_^ ^ ^^^^ and ∆_்ி,^,^,^^ ^^^, in the formula 5 (or formula 6) based on the resource allocation [0068] In response to the 1^st PHR request, the UE 102 generates 314 the 1^st PH in accordance with the reference format indicated in the PHR request and the target waveform. In some implementations, the 1^st PHR request may be a DCI. In one implementation, the DCI is the 1^st DCI. In another implementation, the DCI is different from the 1^st DCI and the base station 104 transmits the 1^st PHR request before the 1^st DCI. In other implementations, the 1^st PHR request may be a MAC control element (CE), and the base station 104 transmits the MAC CE before the 1^st DCI. [0069] Similarly, the base station 104 transmits 317C a 2^nd PHR request requesting a PH involving the target waveform to the UE 102. In some implementations, the base station 104 includes a reference format (e.g., a resource allocation and/or an MCS) in the 2^nd PHR request. In other implementations, the base station 104 does not include a reference format in the 2^nd PHR request. In some implementations, the 2^nd PHR request may be a DCI. In one implementation, the DCI is the 2^nd DCI. In another implementation, the DCI is different from the 2^nd DCI and the base station 104 transmits the 2^nd PHR request before the 2^nd DCI. In other implementations, the 2^nd PHR request may be a MAC control element (CE), and the base station 104 transmits the MAC CE before the 2^nd DCI. After (e.g., in response to) receiving the 2^nd PHR request, the UE 102 generates 314 the 2^nd PH as described for scenario 300A. Because the type-1 resource allocation in the 2^nd DCI is applicable for calculating a PH for the target waveform, the UE 102 generates the 2^nd PH based on the 2^nd DCI and the target waveform, regardless the reference format indicated in the 2^nd PHR request. [0070] Now, referring to Fig.3D, a scenario 300D similar to the scenarios 300A and 300C. The differences between the scenarios 300A and 300D are described below. The base station 104 sends 308D a PHR configuration including one or more than one reference format(s) to the UE 102. The base station 104 then sends 309D a 1^st PHR request requesting a PH involving a target waveform in dynamic waveform switching to the UE 102. The 1^st PHR request includes a reference format indication indicating one of the reference format(s) configured in the PHR configuration 308D. In response to the 1^st PHR request, the UE 102 generates 314 the 1^st PH in accordance with the reference format indicated in the PHR request and the target waveform. Similarly, the base station 104 transmits 317D a 2^nd PHR request requesting a PH involving the target waveform to the UE 102. In some implementations, the base station 104 indicates one of the reference formation(s) in the 2^nd PHR request. In other implementations, the base station 104 does not indicate a reference format in the 2^nd PHR request. After (e.g., in response to) receiving the 2^nd PHR request, the UE 102 generates 314 the 2^nd PH as described for scenario 300A. Because the type-1 resource allocation in the 2^nd DCI is applicable for calculating a PH for the target waveform, the UE 102 generates the 2^nd PH based on the 2^nd DCI and the target waveform, regardless the reference format indicated in the 2^nd PHR request. [0071] In some implementations, if the resource allocation type, in event 304, is configured as type-0 (e.g., resourceAllocationType0), the UE 102 does not apply events 318, 320, 322, and 324 in example scenarios 300A, 300B, 300C, and 300D for PH reporting. [0072] In some implementations, the UE 102 determines to transmit either the legacy PHR format or the PHR format involving waveforms in dynamic waveform switching based on PHR configurations (e.g., events 308A, 308B, 308D) and/or PHR request (events 309C, 309D, 317C, 317D) [0073] In some implementations, the UE 102 generates the PHR involving all waveforms in dynamic waveform switching (e.g., events 314, 322, and 422), where the PH in the PHR for the non-indicated (e.g., non-configured or non-scheduled) waveform is calculated based on the reference format (e.g., events 314, 308B, 308D, 309C, 309D, 317C, 317D), regardless the resource allocation types. [0074] In some implementations, the base station 104 indicates, to the UE 102, additional information (e.g., number of resource blocks (RBs), RB location, FDRA, MCS), on top of the specified reference format, in the PHR configuration (e.g., events 308B, 308D) and/or the PHR request (e.g., events 309C, 309D, 317C, 317D). Then in event 314, the UE 102 generates the PH for the target waveform (e.g., 1^st PH in event 314) according to the specified reference format and the additional information. [0075] Referring to an example scenario 400 illustrated in Fig.4, it is similar to example 300A, except that the UE 102 generates a PH of a target waveform based on actual transmitted PUSCH only. Events 402, 404, 406, 408, 410, 412, 420, and 424 are similar to events 302, 304, 306, 308A, 310, 312, 320, and 324, respectively. Due to the FDRA type, the UE 102 determines that the 1^st PUSCH scheduled by 412 the 1^st DCI is not applicable for generating PH for the target waveform. The UE 102 does not generate the 1^st PHR in accordance with 412 the 1^st DCI, therefore, the UE 102 sends 416 the 1^st PUSCH to the base station 104 without the 1^st PHR. After the UE 102 receives the 2^nd DCI scheduling a 2^nd PUSCH in FDRA type-1, the UE 102 determines the 2^nd PUSCH is applicable for obtaining a PH for the target waveform. In event 422, the UE 102 generates a 1^st PH for the target waveform according to the scheduling information in the 2^nd DCI. [0076] Figs.5A-6C are example MAC CE formats 500A-600C for supporting scenarios described in example scenarios 300A-400, where formats 500A, 500B, and 500C are for single cell PHR, and formats 600A, 600B, and 600C are for multi-cell PHR. [0077] Referring to an example MAC CE format 500A illustrated in Fig.5A, the MAC CE format 500A includes a 2-set PHR information. The 1^st set of PHR information includes a 1^st “PH”, “Pcmax,f,c”, “P”, “R”, “MPE or R” fields for the waveform 1, and the 2^nd set of PHR information includes a 2^nd “PH”, “Pcmax,f,c”, “P”, “R”, “MPE or R” fields for the waveform 2. Field “R” is the reserved field, “P” indicates whether the field “MPE or R” is “MPE” or “R”, and “MPE” is the power reduction of P-MPR. [0078] Referring to an example MAC CE format 500B illustrated in Fig.5B, the MAC CE format 500B is similar to 500A, except that the 2^nd set of PHR information includes the “delta PH” and “delta Pcmax,f,c” among waveform 2 and waveform 1. The “delta PH” may be derived from PH of waveform 2 minus PH of waveform1. Likewise, the “delta P_cmax,f,c” may be derived from Pcmax,f,c of waveform 2 minus Pcmax,f,c of waveform1. [0079] Referring to an example MAC CE format 500C illustrated in Fig.5C, the MAC CE format 500C is similar to 500A, except that 500C includes a 1-set PHR information, where the field “F” indicates the associated waveform for the set of PHR information. For example, if the field “F” is 0, the PH, Pcmax,f,c, and MPE are derived based on waveform 1. Likewise, if the field “F” is 1, the PH, Pcmax,f,c, and MPE are derived based on waveform 2. [0080] Referring to an example MAC CE format 600A illustrated in Fig.6A, the MAC CE format 600A includes a 2-set PHR information for a cell if the cell is configured with dynamic waveform switching. The fields of example format 600A are similar to 500A, except that fields “C1” to “C7” respectively indicates the presence of the set of PH information of Serving Cell 1 to 7. Field “V” indicates whether the set of PH information is derived according to the actual PUSCH transmission or the reference format. [0081] In the example MAC CE format 600A, the PCell and at least the Serving Cell 1 are configured with dynamic waveform switching. There is no cell indicator for the SpCell of another MAC entity and the PCell. Thus, the PHR information of the SpCell of another MAC entity is the legacy 1-set PHR information (refer to 602A), because the SpCell is not configured with dynamic waveform switching. The PHR information of the PCell is a 2-set PHR information (refer to 604A), because the PCell is configured with dynamic waveform switching. If the cell indicator C1 is set to 1, the PHR information of the Serving Cell 1 is present as a 2-set PHR information (refer to 606A), because the Serving Cell 1 is configured with dynamic waveform switching. Likewise, if the cell indicator CX is set to 1, and the Serving Cell X is configured with dynamic waveform switching, the PHR information of the Serving Cell X is a 2-set PHR information. If the cell indicator CX is set to 0, the PHR information of the Serving Cell X is not present in the PHR. [0082] Referring to an example MAC CE format 600B illustrated in Fig.6B, the MAC CE format 600B is similar 600A, except that fields “F1” to “F7” (F1, F2, ..., F7) respectively indicates whether the PHR information of Serving Cell 1 to 7 (C1, C2, ..., C7) are a 1-set or 2-set PHR information. For example, if the field CX (e.g., C1, C2, ..., C7, wherein X = 1, 2, ..., 7) is set to 0, FX (e.g., F1, F2, ..., F7) is set to 0, and the Serving Cell X is configured with dynamic waveform switching, the PHR information of the Serving Cell X is present as a 1-set PHR information. If the field CX is set to 1, FX is set to 1, and the Serving Cell X is configured with dynamic waveform switching, the PHR information of the Serving Cell X is present as a 2-set PHR information. In some cases, the CX and FX may be pre-defined in alternative or different manners, such as when CX or FX is set to 0, the PHR information is a 2-set PHR information; and when CX or FX is set to 1, the PHR information is a 1-set PHR information. Other definitions or configurations are possible. [0083] In some implementations, the MAC CE format includes a field “F0” to indicate whether the PHR information of the PCell is a 1-set or 2-set PHR information. [0084] Referring to an example MAC CE format 600C illustrated in Fig.6C, the MAC CE format 600C is similar 600A, except that the PH information of a cell configured with dynamic waveform switching is a 1-set PH information format with a waveform indication field “F” that is similar to the example format 500C. [0085] In some implementations, the 2-set PH information (e.g., fields 604A, 606A, 604B, 606B) of a cell applies the format of example format 500A or 500B, with a “R” field replaced by the “V” field. [0086] In some implementations, the waveform 1 is CP-OFDM and the waveform 2 is DFT-s-OFDM. In some implementations, the waveform 1 is DFT-s-OFDM and the waveform 2 is CP-OFDM. In some implementations, the waveform 1 is the waveform indicated in the PUSCH scheduling DCI, where the PUSCH includes the PHR, and the waveform 2 is another waveform for dynamic waveform switching. [0087] Turning next to Figs.7, 8A, 8B, 9A, and 9B, which are flow diagrams of example methods 700, 800A, 800B, 900A, and 900B, respectively. These figures generally illustrate various methods for managing dynamic waveform switching and enhanced power headroom reporting configuration from a base station (e.g., the base station 104), and determining how to generate power headroom report accordingly, which may be implemented in a UE (e.g., the UE 102). [0088] Referring first to Fig.7, a UE (e.g., UE 102) may implement method 700 to transmit a power headroom for a waveform to a base station (e.g., base station 104) according to a scheduling DCI or a reference format. As shown, the UE determines 702 to report a PH (e.g., events 310 and 318). The UE receives 704 a DCI scheduling a UL transmission and including a resource allocation from a base station (e.g., events 312 and 320). [0089] The UE determines 706 whether the resource allocation is a resource allocation of a first type. If the UE determines that the resource allocation is a resource allocation of a first type, the UE obtains 708 a PH and/or a PCMAX,f,c, based on a reference format (e.g., event 314). Otherwise, if the UE determines 706 that the resource allocation is not a resource allocation of a first type, the UE obtains 710 a PH and/or a PCMAX,f,c, based on the DCI (e.g., event 322). The UE then transmits 712 a PHR including the PH and/or a PCMAX,f,c to the base station (e.g., events 316 and 324). [0090] Referring next to Fig.8A, a UE (e.g., UE 102) may implement the method 800A to transmit a PHR to a base station (e.g., base station 104), and includes multiple PHs for different waveforms in the PHR (e.g., events 316, 324, 424, and formats 500A, 500B, 600A, 600B). As shown, the UE determines 802 power headroom reporting (e.g., events 310, 318, and 410). The UE obtains 804 a first PH and/or a first PCMAX,f,c for a first waveform (e.g., event 314). The UE obtains 806 a second PH and/or a second P_CMAX,f,c for a second waveform (e.g., events 322 and 422). The UE transmits 808 a PHR including the first PH and/or first P_CMAX,f,c and the second PH and/or second P_CMAX,f,c to the base station (e.g., events 316, 324, and 424). [0091] Referring to Fig.8B, the method 800B is similar to method 800A, except that the UE transmits 807, 809 separate PHRs for PHs of different waveforms to the base station (e.g., with formats 500C and 600C). The differences between the methods 800A and 800B are described below. The UE transmits 807 a first PHR including the first PH and/or first PCMAX,f,c to the base station (e.g., event 316). And the UE separately transmits 809 a second PHR including the second PH and/or second P_CMAX,f,c to the base station (e.g., events 324 and 424). [0092] Referring to Fig.9A, a UE (e.g., UE 102) may implement method 900A to enable enhanced power headroom reporting for waveform(s) based on the PHR configuration received from a RAN (e.g., base station 104). As shown, the UE receives 902 the PHR configuration from the RAN (e.g., events 308A, 308B, 308D, and 408). The UE receives 904 a dynamic waveform switching configuration from the RAN (e.g., events 306 and 406). The UE determines 906 whether the PHR configuration includes a configuration parameter configuring enhanced power headroom reporting for waveform(s) (e.g., events 308A, 308B, 308D, and 408). [0093] If the UE determines 906 that the PHR configuration includes a configuration parameter configuring enhanced power headroom reporting for waveform(s), the UE enables 908 the enhanced power headroom reporting for waveform(s). Otherwise, if the UE determines 906 that the PHR configuration does not include a configuration parameter configuring enhanced power headroom reporting for waveform(s), the UE refrains 910 from enabling or disabling enhanced power headroom reporting for waveform(s) (e.g., by maintaining the current status or PHR configuration). [0094] Regarding to Fig.9B, method 900B is similar to method 900A, except that the UE determines whether to enable enhanced power headroom reporting for waveform(s) according to the dynamic waveform switching configuration received from the base station (e.g., events 306 and 406). The differences between the methods 900A and 900B are described below. As shown, the UE determines 905 whether the UE is configured with dynamic waveform switching. If the UE determines 905 that the UE is configured with dynamic waveform switching, the UE enables 908 the enhanced power headroom reporting for waveform(s). Otherwise, if the UE determines 905 that it is not configured with dynamic waveform switching, the UE refrains 910 from enabling or disabling the enhanced power headroom reporting for the waveform(s). [0095] Turning next to Figs.10, 11A, 11B, and 12, which are flow diagrams of example methods 1000, 1100A, 1100B, and 1200, respectively. Figs.10, 11A, 11B, and 12 generally illustrate various methods for configuring dynamic waveform switching and enhanced power headroom reporting configuration to a UE (e.g., the UE 102), which may be implemented in a base station (e.g., the base station 104). [0096] Regarding first to Fig.10, a base station (e.g., base station 104) may implement method 1000 to determine whether a PH for a waveform in a PHR, received from a UE (e.g., UE 102), is generated based on a reference format or a scheduling DCI. As shown, a base station transmits 1002 a first DCI scheduling a UL transmission and including a resource allocation to a UE (e.g., events 312, 320, 412, and 420). The base station receives 1004 a PHR from the UE on the UL transmission (e.g., events 316, 324, and 424). [0097] The base station determines 1006 whether the resource allocation is a resource allocation of a first type. If the base station determines 1006 that the resource allocation is a resource allocation of a first type, the base station determines 1008 that a PH and/or a P_CMAX,f,c in the PHR are obtained by the UE based on a reference format (e.g., event 316). Otherwise, if the base station determines 1006 that the resource allocation is not a resource allocation of a first type (e.g., the resource allocation is a second type), the base station determines 1010 that a PH and/or a PCMAX,f,c in the PHR are obtained by the UE based on the first DCI (e.g., event 324). Then, the base station determines 1012 an MCS and/or a resource allocation for a UL transmission, based on the PH and/or PCMAX,f,c (e.g., event 324). The base station transmits 1014 a second DCI scheduling a UL transmission to the UE, where the second DCI includes the resource allocation and/or an indication of the MCS. The base station receives 1016 a UL transmission from the UE in accordance with the second DCI. [0098] Regarding next to Fig.11A, a base station (e.g., base station 104) may implement method 1100A to determine the UL transmission scheduling based on one or more PHR, received from a UE (e.g., UE 102), regarding different PH of waveform(s). As shown, a base station receives 1102 a PHR from a UE. The PHR includes a first PH and/or a first P_CMAX,f,c, and a second PH and/or a second P_CMAX,f,c for a first waveform and a second waveform, respectively (e.g., events 316, 324, 424, and formats 500A, 500B, 600A, and 600B). [0099] The base station determines 1104 an MCS, a resource allocation, and/or a waveform for a UL transmission, based on the first PH and/or first PCMAX,f,c and the second PH and/or P_CMAX,f,c. The base station transmits 1106 a DCI scheduling a UL transmission to the UE. The DCI includes the resource allocation, an indication of the MCS, and/or an indication of the waveform. [00100] Regarding to Fig.11B, method 1100B is similar to method 1100A, except that the base station receives 1103 a first PHR and a second PHR from the UE. The first PHR includes a first PH and/or a first P_CMAX,f,c , and the second PHR includes a second PH and/or a second PCMAX,f,c for a first waveform and a second waveform, respectively (e.g., with formats 500C and 600C). [00101] Regarding to Fig.12, a base station (e.g., base station 104) may implement method 1200 to enable a UE (e.g., UE 102) with enhanced power headroom reporting based on the UE capability. At block 1202, the base station communicates with a UE (e.g., to acquire the UE capability). At block 1204, the base station transmits a dynamic waveform switching configuration to the UE (e.g., events 306 and 406). At block 1206, the base station determines whether the UE supports enhanced power headroom reporting for waveform(s). If the base station determines that the UE supports enhanced power headroom reporting for waveform(s), the flow proceeds to block 1208. At block 1208, the base station transmits a configuration to the UE to enable enhanced power headroom reporting for waveform(s). Otherwise, if the base station determines that the UE does not support enhanced power headroom reporting for waveform(s), the flow proceeds to block 1210. At block 1210, the base station refrains from transmitting to the UE a configuration enabling power headroom reporting for waveform(s). [00102] Fig.13 is a flowchart 1300 of a method of wireless communication at a UE. With reference to Figs.1A, 2A, 2B, and 15, the method may be performed by the UE 102, the UE apparatus 1502, etc., which may include the memory 1515', 1506', 1515, and which may correspond to the entire UE 102 or the entire UE apparatus 1502, or a component of the UE 102 or the UE apparatus 1502, such as the wireless baseband processor 1515 and/or the application processor 1506. [00103] In Fig.13, the UE identifies 1310 a triggering event for a power headroom report (PHR) associated with a target waveform. The UE receives 1320, from a network entity (e.g., the BS 104 of Figs.3A-3D), DCI (e.g., the second DCI 320 or 420 discussed above) providing a resource allocation for an uplink transmission using a waveform different from the target waveform. The UE transmits 1324, to the network entity, the PHR in the uplink transmission, the PHR including a power headroom calculated based on the resource allocation provided by the DCI and the target waveform. [00104] Fig.14 is a flowchart 1400 of a method of wireless communication at a network entity. With reference to Figs.1A, 1B, 2A, 2B, and 16, the method may be performed by one or more network entities 104, which may correspond to a base station or a unit of the base station, such as the RU 956, the DU 958, the CU 960, an RU processor 15406, a DU processor 1613, a CU processor 1646, etc. The one or more network entities 104 may include memory 15406’/1613’/1646’, which may correspond to an entirety of the one or more network entities 104, or a component of the one or more network entities 104, such as the RU processor 15406, the DU processor 1613, or the CU processor 1646. [00105] In Fig.14, the network entity transmits 1402, to a UE (e.g., the UE 102), a DCI providing a resource allocation for an uplink transmission by the UE. The network entity then receives 1404, from the UE, the uplink transmission including a PHR including a power headroom calculated based on the resource allocation provided by the DCI and a target waveform different from a waveform of the uplink transmission scheduled by the DCI. The network entity then uses 1412 a modulation and coding scheme (MCS) or an updated resource allocation determined based on the power headroom for scheduling further transmissions from the UE. [00106] Referring to both Figs.13 and 14, in aspects, the target waveform includes a discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-s- OFDM). In some cases, transmitting the PHR to the network entity causes the network entity to have the UE transmit future uplink transmissions in the target waveform. [00107] In aspects, the uplink transmission is via a physical uplink shared channel (PUSCH) scheduled by the DCI. In some cases, the UE transmits to the network entity the uplink transmission using a cyclic prefix orthogonal frequency division multiplexing (CP- OFDM) waveform. [00108] In aspects, the PHR includes a maximum available transmission power, along with or instead of the power headroom of the resource allocation and the target waveform. [00109] In aspects, the resource allocation uses a non-contiguous frequency resource block. The UE calculates the power headroom using a reference format providing power reduction values. [00110] In aspects, the resource allocation uses a contiguous frequency resource block, and the UE calculates the power headroom using the DCI and power related parameters therein. In some cases, the power headroom is calculated using the power related parameters of the DCI only. [00111] In some cases, the UE receives a PHR configuration message from the network entity (e.g., before a triggering event). The PHR configuration message includes a first set of parameters of the reference format. In some cases, the UE receives, from the network entity, a request for the PHR associated with the target waveform. For example, the request includes a second set of parameters of the reference format to be used in the place of the first set of parameters. The PHR configuration message includes a plurality of reference formats. [00112] In some cases, the UE receives, from the network entity, a request for the PHR associated with the target waveform. The request indicates one of the plurality of reference formats in the PHR configuration message. For example, the PHR configuration message includes a radio resource control (RRC) message (e.g., a RRC reconfiguration message) including a PHR configuration, and wherein the request for the PHR includes a medium access control (MAC) control element (CE) or a downlink control information (DCI). [00113] In aspects, the UE receives, from the network entity, a configuration enabling the UE to dynamically switch between a first waveform and the target waveform. In some cases, the UE enables an enhanced power headroom reporting for both the first and the target waveforms upon receiving the configuration. The UE maintains a current configuration regarding the enhanced power headroom reporting in an absence of receiving the configuration. For example, enabling the enhanced power headroom reporting is conditioned upon the UE applying the configuration received from the network entity enabling the UE to dynamically switch between the first waveform and the target waveform. [00114] In aspects, the uplink transmission includes a medium access control (MAC) control element (CE), which includes multiple sets of PHR information respective for the target waveform and a current waveform. In some cases, the multiple sets of PHR information include power headroom information for both the target and the current waveforms. The multiple sets of PHR information include power headroom information for one of the two waveforms and a differential value for the other one of the two waveforms. [00115] In some cases, the MAC CE includes an indicator specifying a power headroom value for one of the two waveforms. In some cases, the MAC CE includes a plurality sets of PHR information for both the target and current waveforms in use with multiple serving cells. For example, the MAC CE further includes an indicator identifying a subset of the plurality sets of PHR information including both sets of PHR information for dynamic waveform switching. The MAC CE may further include an indicator specifying a power headroom value for one of the two waveforms in one of the plurality sets of PHR information for one of the multiple serving cells. [00116] In aspects, the triggering event includes at least one of: an expiration of a prohibit timer; an expiration of a periodic timer; a change of path loss; an activation of a secondary cell; an addition of a primary secondary cell; a switch of activated bandwidth part; a configuration or reconfiguration of the PHR; a change of power headroom; a change of power headroom difference between two waveforms; or a change of power headroom ratio between two waveforms. [00117] Fig.15 is a diagram 1500 illustrating an example hardware implementation for a UE apparatus 1502. The UE apparatus 1502 may be the UE 102, a component of the UE 102, or may implement UE functionality. The UE apparatus 1502 may include an application processor 1506, which may have on-chip memory 1506’. In examples, the application processor 1506 may be coupled to a secure digital (SD) card 1508 and/or a display 1510. The application processor 1506 may also be coupled to a sensor(s) module 1512, a power supply 1516, an additional module of memory 1515, a camera 1518, and/or other related components. For example, the sensor(s) module 1512 may control a barometric pressure sensor/altimeter, a motion sensor such as an inertial management unit (IMU), a gyroscope, accelerometer(s), a light detection and ranging (LIDAR) device, a radio-assisted detection and ranging (RADAR) device, a sound navigation and ranging (SONAR) device, a magnetometer, an audio device, and/or other technologies used for positioning. [00118] The UE apparatus 1502 may further include a wireless baseband processor 1515, which may be referred to as a modem. The wireless baseband processor 1515 may have on-chip memory 1515'. Along with, and similar to, the application processor 1506, the wireless baseband processor 1515 may also be coupled to the sensor(s) module 1512, the power supply 1516, the additional module of memory 1515, the camera 1518, and/or other related components. The wireless baseband processor 1515 may be additionally coupled to one or more subscriber identity module (SIM) card(s) 1520 and/or one or more transceivers 1530 (e.g., wireless RF transceivers). [00119] Within the one or more transceivers 1530, the UE apparatus 1502 may include a Bluetooth module 1532, a WLAN module 1534, an SPS module 1536 (e.g., GNSS module), and/or a cellular module 1538. The Bluetooth module 1532, the WLAN module 1534, the SPS module 1536, and the cellular module 1538 may each include an on-chip transceiver (TRX), or in some cases, just a transmitter (TX) or just a receiver (RX). The Bluetooth module 1532, the WLAN module 1534, the SPS module 1536, and the cellular module 1538 may each include dedicated antennas and/or utilize antennas 1540 for communication with one or more other nodes. For example, the UE apparatus 1502 may communicate through the transceiver(s) 1530 via the antennas 1540 with another UE 102 (e.g., sidelink communication) and/or with a network entity 104 (e.g., uplink/downlink communication), where the network entity 104 may correspond to a base station or a unit of the base station, such as the RU 956, the DU 958, or the CU 960. [00120] The wireless baseband processor 1515 and the application processor 1506 may each include a computer-readable medium / memory 1515', 1506', respectively. The additional module of memory 1515 may also be considered a computer-readable medium / memory. Each computer-readable medium / memory 1515', 1506', 1515 may be non- transitory. The wireless baseband processor 1515 and the application processor 1506 may each be responsible for general processing, including execution of software stored on the computer-readable medium / memory 1515', 1506', 1515. The software, when executed by the wireless baseband processor 1515 / application processor 1506, causes the wireless baseband processor 1515 / application processor 1506 to perform the various functions described herein. The computer-readable medium / memory may also be used for storing data that is manipulated by the wireless baseband processor 1515 / application processor 1506 when executing the software. The wireless baseband processor 1515 / application processor 1506 may be a component of the UE 102. The UE apparatus 1502 may be a processor chip (e.g., modem and/or application) and include just the wireless baseband processor 1515 and/or the application processor 1506. In other examples, the UE apparatus 1502 may be the entire UE 102 and include the additional modules of the apparatus 1502. [00121] The PHR manager 1540 may perform various operations and procedures above for calculating power headroom and processing PHR and be within the application processor 1506 (e.g., at 1540a), the wireless baseband processor 1515 (e.g., at 1540b), or both the application processor 1506 and the wireless baseband processor 1515. The PHR manager 1540a-1540b may be one or more hardware components specifically configured to carry out the stated processes/algorithm, implemented by one or more processors configured to perform the stated processes/algorithm, stored within a computer-readable medium for implementation by the one or more processors, or a combination thereof. [00122] The UE apparatus 1502 may include a variety of components configured for various functions. In examples, the UE apparatus 1502, and in particular the wireless baseband processor 1515 and/or the application processor 1506, includes means for identifying, by the UE, a triggering event for a PHR associated with a target waveform; means for receiving, from a network entity, DCI providing a resource allocation for an uplink transmission using a waveform different from the target waveform; and means for transmitting, to the network entity, the PHR in the uplink transmission, the PHR including a power headroom calculated based on the resource allocation provided by the DCI and the target waveform. The means may be the PHR manager 1540a-1540b of the UE apparatus 1502 configured to perform the functions recited by the means. [00123] Fig.16 is a diagram 1600 illustrating an example hardware implementation for one or more network entities 104. The one or more network entities 104 may be a base station, a component of a base station, or may implement base station functionality. The one or more network entities 104 may include, or may correspond to, at least one of the RU 956, the DU, 108, or the CU 960. The CU 960 may include a CU processor 1646, which may have on-chip memory 1646'. In some aspects, the CU 960 may further include an additional module of memory 1656 and/or a communications interface 1648, both of which may be coupled to the CU processor 1646. The CU 960 may communicate with the DU 958 through a midhaul link 162, such as an F1 interface between the communications interface 1648 of the CU 960 and a communications interface 1628 of the DU 958. [00124] The DU 958 may include a DU processor 1615, which may have on-chip memory 1615'. In some aspects, the DU 958 may further include an additional module of memory 1636 and/or the communications interface 1628, both of which may be coupled to the DU processor 1615. The DU 958 may communicate with the RU 956 through a fronthaul link 160 between the communications interface 1628 of the DU 958 and a communications interface 1608 of the RU 956. [00125] The RU 956 may include an RU processor 1606, which may have on-chip memory 1606'. In some aspects, the RU 956 may further include an additional module of memory 1615, the communications interface 1608, and one or more transceivers 1630, all of which may be coupled to the RU processor 1606. The RU 956 may further include antennas 1640, which may be coupled to the one or more transceivers 1630, such that the RU 956 may communicate through the one or more transceivers 1630 via the antennas 1640 with the UE 102. [00126] The on-chip memory 1606', 1615', 1646' and the additional modules of memory 1615, 1636, 1656 may each be considered a computer-readable medium / memory. Each computer-readable medium / memory may be non-transitory. Each of the processors 1606, 1615, 1646 is responsible for general processing, including execution of software stored on the computer-readable medium / memory. The software, when executed by the corresponding processor(s) 1606, 1615, 1646 causes the processor(s) 1606, 1615, 1646 to perform the various functions described herein. The computer-readable medium / memory may also be used for storing data that is manipulated by the processor(s) 1606, 1615, 1646 when executing the software. In examples, the PHR manager 1650 may sit at any of the one or more network entities 104 (e.g., as the PHR managers 1650a, 1650b, and/or 1650c), such as at the CU 960; both the CU 960 and the DU 958; each of the CU 960, the DU 958, and the RU 956; the DU 958; both the DU 958 and the RU 956; or the RU 956. [00127] The PHR manager 1650 may include means for transmitting, to a UE, DCI providing a resource allocation for an uplink transmission by the UE; means for receiving, from the UE, the uplink transmission including a PHR including a power headroom calculated based on the resource allocation provided by the DCI and a target waveform different from a waveform of the uplink transmission scheduled by the DCI; and means for using a MCS or an updated resource allocation determined based on the power headroom for scheduling further transmissions from the UE. [00128] Generally speaking, description for one of the above figures may apply to another of the above figures. An event or block described above may be optional or omitted. For example, an event or block with dashed lines in the figures may be optional. In some implementations, “message” is used and may be replaced by “information element (IE)”, and vice versa. In some implementations, “IE” is used and may be replaced by “field”, and vice versa. In some implementations, “configuration” may be replaced by “configuration(s)” or “configuration parameter(s)”, and vice versa. In some implementations, “PUSCH” may be replaced by “PUSCH transmission” or “a transmission on a PUSCH”. [00129] A user device in which the techniques of this disclosure may be implemented (e.g., the UE 102) may be any suitable device capable of wireless communications such as a smartphone, a tablet computer, a laptop computer, a mobile gaming console, a point-of-sale (POS) terminal, a health monitoring device, a drone, a camera, a media-streaming dongle or another personal media device, a wearable device such as a smartwatch, a wireless hotspot, a femtocell, or a broadband router. Further, the user device in some cases may be embedded in an electronic system such as the head unit of a vehicle or an advanced driver assistance system (ADAS). Still further, the user device may operate as an internet-of-things (IoT) device or a mobile-internet device (MID). Depending on the type, the user device may include one or more general-purpose processors, a computer-readable memory, a user interface, one or more network interfaces, one or more sensors, etc. [00130] Certain embodiments are described in this disclosure as including logic or a number of components or modules. Modules may be software modules (e.g., code stored on non-transitory machine-readable medium) or hardware modules. A hardware module is a tangible unit capable of performing certain operations and may be configured or arranged in a certain manner. A hardware module may comprise dedicated circuitry or logic that is permanently configured (e.g., as a special-purpose processor, such as a field programmable gate array (FPGA) or an application-specific integrated circuit (ASIC)) to perform certain operations. A hardware module may also comprise programmable logic or circuitry (e.g., as encompassed within a general-purpose processor or other programmable processor) that is temporarily configured by software to perform certain operations. The decision to implement a hardware module in dedicated and permanently configured circuitry, or in temporarily configured circuitry (e.g., configured by software) may be driven by cost and time considerations. [00131] When implemented in software, the techniques may be provided as part of the operating system, a library used by multiple applications, a particular software application, etc. The software may be executed by one or more general-purpose processors or one or more special-purpose processors. [00132] Upon reading this disclosure, those of skill in the art will appreciate still additional alternative structural and functional designs for managing multi-cell PDSCH transmissions through the disclosed principles herein. Thus, while particular embodiments and applications have been illustrated and described, it is to be understood that the disclosed embodiments are not limited to the precise construction and components disclosed herein. Various modifications, changes and variations, which will be apparent to those of ordinary skill in the art, may be made in the arrangement, operation and details of the method and apparatus disclosed herein without departing from the spirit and scope defined in the appended claims. Example Aspects Example 1 is a method for wireless communications by a user equipment (UE), the method comprising: identifying, by the UE, a triggering event for a power headroom report (PHR) associated with a target waveform; receiving, from a network entity, downlink control information (DCI) providing a resource allocation for an uplink transmission using a waveform different from the target waveform; and transmitting, to the network entity, the PHR in the uplink transmission, the PHR including a power headroom calculated based on the resource allocation provided by the DCI and the target waveform. Example 2 is a method of example 1, wherein the target waveform comprises a discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-s- OFDM). Example 3 is a method of example 2, wherein transmitting the PHR to the network entity causes the network entity to have the UE transmit future uplink transmissions in the target waveform. Example 4 is a method of example 1, wherein the resource allocation includes at least one of a first type of frequency domain resource allocation (FDRA) or a second type of FDRA different from the first type of FDRA, and the method further comprising: calculating the power headroom using a reference format providing power reduction values when the resource allocation includes the first type of FDRA; and calculating the power headroom using power related parameters provided in the DCI when the resource allocation includes the second type of FDRA. Example 5 is a method of example 4, further comprising: transmitting, by the UE to the network entity, the uplink transmission using a cyclic prefix orthogonal frequency division multiplexing (CP-OFDM) waveform. Example 6 is a method of example 1, wherein the PHR comprises a maximum available transmission power, along with or instead of the power headroom of the resource allocation and the target waveform. Example 7 is a method of example 1, wherein the resource allocation uses a non- contiguous frequency resource block, and the method further comprising: calculating the power headroom using a reference format providing power reduction values. Example 8 is a method of example 1, wherein the resource allocation uses a contiguous frequency resource block, and the method further comprising: calculating the power headroom using the DCI and power related parameters therein. Example 9 is a method of example 8, wherein the power headroom is calculated using the power related parameters of the DCI only. Example 10 is a method of example 7 or 8, further comprising: receiving a PHR configuration message from the network entity. Example 11 is a method of example 10, wherein the PHR configuration message comprises a first set of parameters of the reference format. Example 12 is a method of example 11, further comprising: receiving, from the network entity, a request for the PHR associated with the target waveform. Example 13 is a method of example 12, wherein the request comprises a second set of parameters of the reference format to be used in the place of the first set of parameters. Example 14 is a method of example 12, wherein the PHR configuration message comprises a plurality of reference formats, and the method further comprising: receiving, from the network entity, a request for the PHR associated with the target waveform, wherein the request indicates one of the plurality of reference formats in the PHR configuration message. Example 15 is a method of example 12, wherein the PHR configuration message comprises a radio resource control (RRC), and wherein the request for the PHR comprises a medium access control (MAC) control element (CE) or another downlink control information (DCI). Example 16 is a method of example 1, further comprising: receiving, from the network entity, a configuration enabling the UE to dynamically switch between a first waveform and the target waveform. Example 17 is a method of example 9, further comprising: enabling an enhanced power headroom reporting for both the first and the target waveforms upon receiving the configuration; and maintaining a current configuration regarding the enhanced power headroom reporting in an absence of receiving the configuration. Example 18 is a method of example 17, wherein enabling the enhanced power headroom reporting is conditioned upon the UE applying the configuration received from the network entity enabling the UE to dynamically switch between the first waveform and the target waveform. Example 19 is a method of example 1, wherein the uplink transmission comprises a medium access control (MAC) control element (CE), which includes multiple sets of PHR information respective for the target waveform and a current waveform. Example 20 is a method of example 19, wherein the multiple sets of PHR information include power headroom information for both the target and the current waveforms. Example 21 is a method of example 19, wherein the multiple sets of PHR information include power headroom information for one of the two waveforms and a differential value for the other one of the two waveforms. Example 22 is a method of example 19, wherein the MAC CE includes an indicator specifying a power headroom value for one of the two waveforms. Example23 is a method of example 19, wherein the MAC CE includes a plurality sets of PHR information for both the target and current waveforms in use with multiple serving cells. Example 24 is a method of example 23, wherein the MAC CE further includes an indicator identifying a subset of the plurality sets of PHR information including both sets of PHR information for dynamic waveform switching. Example 25 is a method of example 23, wherein the MAC CE further includes an indicator specifying a power headroom value for one of the two waveforms in one of the plurality sets of PHR information for one of the multiple serving cells. Example 26 is a method of example 1, wherein the triggering event comprises at least one of: an expiration of a prohibit timer; an expiration of a periodic timer; a change of path loss; an activation of a secondary cell; an addition of a primary secondary cell; a switch of activated bandwidth part; a configuration or reconfiguration of the PHR; a change of power headroom; a change of power headroom difference between two waveforms; or a change of power headroom ratio between two waveforms. Example 27 is a method for wireless communications by a network entity, the method comprising: transmitting, to a user equipment (UE), downlink control information (DCI) providing a resource allocation for an uplink transmission by the UE; and receiving, from the UE, the uplink transmission including a power headroom report (PHR) including a power headroom calculated based on the resource allocation provided by the DCI and a target waveform different from a waveform of the uplink transmission scheduled by the DCI. Example 28 is a method of example 27, further comprising: scheduling another uplink transmission including a modulation and coding scheme (MCS) and an updated resource allocation determined based on the PHR. Example 29 is a method of example 27, further comprising: determining that the power headroom in the PHR has been calculated by the UE based on a reference format when the resource allocation of the transmitted DCI is of a first type using a contiguous frequency resource block; or determining that the power headroom in the PHR has been calculated by the UE based on the DCI when the resource allocation of the transmitted DCI is of a second type using a non-contiguous frequency resource block. Example 30 is a method of example 27, further comprising: transmitting, to the UE, a second DCI scheduling a second uplink transmission, the second DCI including the resource allocation or an indication of the MCS; and receiving, from the UE, the second uplink transmission in accordance with the second DCI. Example 31 is a method of example 27, wherein the target waveform comprises a discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-s- OFDM). Example 32 is a method of example 31, wherein receiving the uplink transmission including the PHR from the UE causes the network entity to have the UE transmit future uplink transmissions in the target waveform. Example 33 is a method of example 27, wherein the resource allocation includes at least one of a first type of frequency domain resource allocation (FDRA) or a second type of FDRA different from the first type of FDRA, and the method further comprising: calculating the power headroom using a reference format providing power reduction values when the resource allocation includes the first type of FDRA; and calculating the power headroom using power related parameters provided in the DCI when the resource allocation includes the second type of FDRA. Example 34 is a method of example 33, further comprising: receiving, from the UE, the uplink transmission using a cyclic prefix orthogonal frequency division multiplexing (CP-OFDM) waveform. Example 35 is a method of example 27, wherein the PHR comprises a maximum available transmission power, along with or instead of the power headroom of the resource allocation and the target waveform. Example 36 is a method of example 27, further comprising: transmitting a PHR configuration message to the UE. Example 37 is a method of example 36, wherein the resource allocation uses a non- contiguous frequency resource block, and wherein the power headroom is calculated by the UE using a reference format providing power reduction values. Example 38 is a method of example 36, wherein the resource allocation uses a contiguous frequency resource block, and wherein the power headroom is calculated by the UE using the DCI and power related parameters therein. Example 39 is a method of example 38, wherein the power headroom is calculated using the power related parameters of the DCI only. Example 40 is a method of example 36, wherein the PHR configuration message comprises a first set of parameters of the reference format. Example 41 is a method of example 40, further comprising: transmitting, to the UE, a request for the PHR associated with the target waveform. Example 42 is a method of example 41, wherein the request comprises a second set of parameters of the reference format to be used in the place of the first set of parameters. Example 43 is a method of example 41, wherein the PHR configuration message comprises a plurality of reference formats, and the method further comprising: transmitting, to the UE, a request for the PHR associated with the target waveform, wherein the request indicates one of the plurality of reference formats in the PHR configuration message. Example 44 is a method of example 41, wherein the PHR configuration message comprises a radio resource control (RRC), and wherein the request for the PHR comprises a medium access control (MAC) control element (CE) or another downlink control information (DCI). Example 45 is a method of example 27, further comprising: transmitting, to the UE, a configuration to enable the UE to dynamically switch between a first waveform and the target waveform. Example 46 is a method of example 27, wherein the received uplink transmission comprises a medium access control (MAC) control element (CE), which includes multiple sets of PHR information respective for the target waveform and a current waveform. Example 47 is a method of example 46, wherein the multiple sets of PHR information include power headroom information for both the target and the current waveforms. Example 48 is a method of example 46, wherein the multiple sets of PHR information include power headroom information for one of the two waveforms and a differential value for the other one of the two waveforms. Example 49 is a method of example 46, wherein the MAC CE includes an indicator specifying a power headroom value for one of the two waveforms. Example 50 is a method of example 46, wherein the MAC CE includes a plurality sets of PHR information for both the target and current waveforms in use with multiple serving cells. Example 51 is a method of example 50, wherein the MAC CE further includes an indicator identifying a subset of the plurality sets of PHR information including both sets of PHR information for dynamic waveform switching. Example 52 is a method of example 50, wherein the MAC CE further includes an indicator specifying a power headroom value for one of the two waveforms in one of the plurality sets of PHR information for one of the multiple serving cells. Example 53 is an apparatus for wireless communication comprising a transceiver, a memory, and a processor coupled to the memory and the transceiver, the apparatus being configured to implement a method as in any of examples 1-52.

Claims

WHAT IS CLAIMED IS: 1. A method for wireless communications by a user equipment (UE), the method comprising: identifying (310), by the UE, a triggering event for a power headroom report (PHR) associated with a target waveform; receiving (312), from a network entity, downlink control information (DCI) providing a resource allocation for an uplink transmission using a waveform different from the target waveform; and transmitting (316), to the network entity, the PHR in the uplink transmission, the PHR including a power headroom calculated based on the resource allocation provided by the DCI and the target waveform.

2. The method of claim 1, wherein the PHR comprises a maximum available transmission power, along with the power headroom of the resource allocation and the target waveform.

3. The method of claim 1 or 2, wherein the resource allocation includes at least one of a first type of frequency domain resource allocation (FDRA) or a second type of FDRA different from the first type of FDRA, and the method further comprising: calculating the power headroom using a reference format providing power reduction values when the resource allocation includes the first type of FDRA; and calculating the power headroom using power related parameters provided in the DCI when the resource allocation includes the second type of FDRA.

4. The method of claim 3, further comprising: receiving (308) a PHR configuration message from the network entity, wherein the PHR configuration message comprises a first set of parameters of the reference format.

5. The method of claim 4, further comprising: receiving, from the network entity, a request for the PHR associated with the target waveform, wherein the request comprises a second set of parameters of the reference format to be used instead of the first set of parameters.

6. The method of claim 4, wherein the PHR configuration message comprises a plurality of reference formats, and the method further comprising: receiving, from the network entity, a request for the PHR associated with the target waveform, wherein the request indicates one of the plurality of reference formats in the PHR configuration message.

7. The method of any one of claims 4 to 6, wherein the PHR configuration message comprises a radio resource control (RRC) message, and wherein the request for the PHR comprises a medium access control (MAC) control element (CE) or another DCI.

8. The method of any one of claims 1 to 7, further comprising: receiving (306), from the network entity, a configuration enabling the UE to dynamically switch between a first waveform and the target waveform.

9. The method of any one of claims 1 to 8, wherein the uplink transmission comprises a medium access control (MAC) control element (CE) including multiple sets of PHR information for the target waveform and a current waveform, respectively.

10. The method of claim 9, wherein: the multiple sets of PHR information include power headroom information for both the target and the current waveforms; the multiple sets of PHR information include power headroom information for one of the target and the current waveforms and a differential value for the other one of the target and the current waveforms; the MAC CE includes an indicator specifying a power headroom value for one of the target and the current waveforms; or the MAC CE includes a plurality sets of PHR information for both the target and current waveforms in use with multiple serving cells.

11. The method of any one of claims 1 to 10, wherein the triggering event comprises at least one of: an expiration of a prohibit timer; an expiration of a periodic timer; a change of path loss; an activation of a secondary cell; an addition of a primary secondary cell; a switch of activated bandwidth part; a configuration or reconfiguration of the PHR; a change of power headroom; a change of power headroom difference between two waveforms; or a change of power headroom ratio between two waveforms.

12. A method for wireless communications by a network entity, the method comprising: transmitting (312), to a user equipment (UE), downlink control information (DCI) providing a resource allocation for an uplink transmission; and receiving (316), from the UE, a power headroom report in the uplink transmission, the power headroom report (PHR) including a power headroom calculated based on the resource allocation provided by the DCI and a target waveform different from a waveform of the uplink transmission scheduled by the DCI.

13. The method of claim 12, further comprising: scheduling (320) another uplink transmission including a modulation and coding scheme (MCS) and an updated resource allocation determined based on the PHR.

14. The method of claim 12 or 13, further comprising: determining that the power headroom in the PHR has been calculated by the UE based on a reference format when the resource allocation of the transmitted DCI is of a first type of frequency domain resource allocation (FDRA); or determining that the power headroom in the PHR has been calculated by the UE based on the DCI when the resource allocation of the transmitted DCI is of a second type of FDRA different from the first type of FDRA.

15. An apparatus for wireless communication comprising a transceiver, a memory, and a processor coupled to the memory and the transceiver, the apparatus being configured to implement a method as in any of claims 1-14.