High dynamic range reference signal for estimation and correction of power amplifier non-linearity

Abstract

A method for wireless communication by a user equipment (UE) includes transmitting a request, to a network device, for transmitting a non-linearity reference signal (NLRS), in response to beginning communication with the network in a high power mode or in response to detecting variation of a non-linearity distortion model. The method also includes receiving, from the network device, permission for uplink transmission of the non-linearity reference signal. The method further includes transmitting the non-linearity reference signal to the network device. The non-linearity reference signal may be a dedicated pilot signal or a sounding reference signal (SRS) having an increased dynamic range.

Description

Qualcomm Ref. No.2308905WO HIGH DYNAMIC RANGE REFERENCE SIGNAL FOR ESTIMATION AND CORRECTION OF POWER AMPLIFIER NON-LINEARITY CROSS-REFERENCE TO RELATED APPLICATION

[0001] The present application claims priority to Israel Patent Application No.308991, filed on November 30, 2023, and titled “HIGH DYNAMIC RANGE REFERENCE SIGNAL FOR ESTIMATION AND CORRECTION OF POWER AMPLIFIER NON-LINEARITY,” the disclosure of which is expressly incorporated by reference in its entirety. FIELD OF THE DISCLOSURE

[0002] The present disclosure relates generally to wireless communications, andmore specifically to a high dynamic range reference signal (RS) for estimating and correcting non-linearities in a power amplifier (PA) of a user equipment (UE). BACKGROUND

[0003] Wireless communications systems are widely deployed to provide varioustelecommunications services such as telephony, video, data, messaging, and broadcasts. Typical wireless communications systems may employ multiple-access technologies capable of supporting communications with multiple users by sharing available system resources (e.g., bandwidth, transmit power, and / or the like). Examples of such multiple- access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency-division multiple access (FDMA) systems, orthogonal frequency-division multiple access (OFDMA) systems, single- carrier frequency-division multiple access (SC-FDMA) systems, time division synchronous code division multiple access (TD-SCDMA) systems, and long term evolution (LTE). LTE / LTE-Advanced is a set of enhancements to the universal mobile telecommunications system (UMTS) mobile standard promulgated by the Third Generation Partnership Project (3GPP). Narrowband (NB)-Internet of things (IoT) and enhanced machine-type communications (eMTC) are a set of enhancements to LTE for machine type communications.Seyfarth Ref. No. 72178-006686 1314499932v.1Qualcomm Ref. No.2308905WO

[0004] A wireless communications network may include a number of base stations(BSs) that can support communications for a number of user equipment (UEs). A user equipment (UE) may communicate with a base station (BS) via the downlink and uplink. The downlink (or forward link) refers to the communication link from the BS to the UE, and the uplink (or reverse link) refers to the communication link from the UE to the BS. As will be described in more detail, a BS may be referred to as a Node B, an evolved Node B (eNB), a gNB, an access point (AP), a radio head, a transmit and receive point (TRP), a new radio (NR) BS, a 5G Node B, and / or the like.

[0005] The above multiple access technologies have been adopted in varioustelecommunications standards to provide a common protocol that enables different user equipment to communicate on a municipal, national, regional, and even global level. New radio (NR), which may also be referred to as 5G, is a set of enhancements to the LTE mobile standard promulgated by the Third Generation Partnership Project (3GPP). NR is designed to better support mobile broadband Internet access by improving spectral efficiency, lowering costs, improving services, making use of new spectrum, and better integrating with other open standards using orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) (CP-OFDM) on the downlink (DL), using CP-OFDM and / or SC-FDM (e.g., also known as discrete Fourier transform spread OFDM (DFT-s-OFDM)) on the uplink (UL), as well as supporting beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation. SUMMARY

[0006] In aspects of the present disclosure, a method for wireless communication bya user equipment (UE) includes transmitting a request, to a network device, for transmitting a non-linearity reference signal (NLRS), in response to beginning communication with the network in a high power mode or in response to detecting variation of a non-linearity distortion model. The method also includes receiving, from the network device, permission for uplink transmission of the non-linearity reference signal. The method further includes transmitting the non-linearity reference signal to the network device.

[0007] In other aspects of the present disclosure, a method for wirelesscommunication by a network device includes transmitting, to a user equipment (UE),Seyfarth Ref. No. 72178-006686 2314499932v.1Qualcomm Ref. No.2308905WO permission for uplink transmission of a non-linearity reference signal (NLRS) in response to receiving, from the UE, a request for transmitting the non-linearity reference signal. The method also includes receiving, from the UE, the non-linearity reference signal. The method further includes estimating a non-linearity distortion model based on receiving the non-linearity reference signal. The method still further includes removing a non-linearity effect from a signal received from the UE in a subsequent slot, based on the non-linearity distortion model, to obtain a corrected signal.

[0008] Other aspects of the present disclosure are directed to an apparatus. Theapparatus has one or more memories and one or more processors coupled to the one or more memories. The processor(s) is configured to transmit a request, to a network device, for transmitting a non-linearity reference signal (NLRS), in response to beginning communication with the network in a high power mode or in response to detecting variation of a non-linearity distortion model. The processor(s) is also configured to receive, from the network device, permission for uplink transmission of the non-linearity reference signal. The processor(s) is further configured to transmit the non-linearity reference signal to the network device.

[0009] Other aspects of the present disclosure are directed to an apparatus. Theapparatus has one or more memories and one or more processors coupled to the one or more memories. The processor(s) is configured to transmit, to a user equipment (UE), permission for uplink transmission of a non-linearity reference signal (NLRS) in response to receiving, from the UE, a request for transmitting the non-linearity reference signal. The processor(s) is also configured to receive, from the UE, the non-linearity reference signal. The processor(s) is further configured to estimate a non-linearity distortion model based on receiving the non-linearity reference signal. The processor(s) is still further configured to remove a non-linearity effect from a signal received from the UE in a subsequent slot, based on the non-linearity distortion model, to obtain a corrected signal.

[0010] Aspects generally include a method, apparatus, system, computer programproduct, non-transitory computer-readable medium, user equipment, base station, wireless communication device, and processing system as substantially described with reference to and as illustrated by the accompanying drawings and specification.Seyfarth Ref. No. 72178-006686 3314499932v.1Qualcomm Ref. No.2308905WO

[0011] The foregoing has outlined rather broadly the features and technicaladvantages of examples according to the disclosure in order that the detailed description that follows may be better understood. Additional features and advantages will be described. The conception and specific examples disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. Such equivalent constructions do not depart from the scope of the appended claims. Characteristics of the concepts disclosed, both their organization and method of operation, together with associated advantages will be better understood from the following description when considered in connection with the accompanying figures. Each of the figures is provided for the purposes of illustration and description, and not as a definition of the limits of the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] So that features of the present disclosure can be understood in detail, aparticular description may be had by reference to aspects, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only certain aspects of this disclosure and are therefore not to be considered limiting of its scope, for the description may admit to other equally effective aspects. The same reference numbers in different drawings may identify the same or similar elements.

[0013] FIGURE 1 is a block diagram conceptually illustrating an example of awireless communications network, in accordance with various aspects of the present disclosure.

[0014] FIGURE 2 is a block diagram conceptually illustrating an example of a basestation in communication with a user equipment (UE) in a wireless communications network, in accordance with various aspects of the present disclosure.

[0015] FIGURE 3 is a block diagram illustrating an example disaggregated basestation architecture, in accordance with various aspects of the present disclosure.

[0016] FIGURES 4A to 4D are graphs illustrating transmitted data samples andpilot signals, in accordance with various aspects of the present disclosure.Seyfarth Ref. No. 72178-006686 4314499932v.1Qualcomm Ref. No.2308905WO

[0017] FIGURE 5 is a call flow diagram illustrating communications related to anon-linearity reference signal (NLRS), in accordance with various aspects of the present disclosure.

[0018] FIGURE 6 is a power spectral density graph of compressed anduncompressed signals, in accordance with various aspects of the present disclosure.

[0019] FIGURE 7 is a flow diagram illustrating an example process performed, forexample, by a user equipment (UE), in accordance with various aspects of the present disclosure.

[0020] FIGURE 8 is a flow diagram illustrating an example process performed, forexample, by a network device, in accordance with various aspects of the present disclosure. DETAILED DESCRIPTION

[0021] Various aspects of the disclosure are described more fully below withreference to the accompanying drawings. This disclosure may, however, be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Based on the teachings, one skilled in the art should appreciate that the scope of the disclosure is intended to cover any aspect of the disclosure, whether implemented independently of or combined with any other aspect of the disclosure. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth. In addition, the scope of the disclosure is intended to cover such an apparatus or method, which is practiced using other structure, functionality, or structure and functionality in addition to or other than the various aspects of the disclosure set forth. It should be understood that any aspect of the disclosure disclosed may be embodied by one or more elements of a claim.

[0022] Several aspects of telecommunications systems will now be presented withreference to various apparatuses and techniques. These apparatuses and techniques will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, components, circuits, steps, processes,Seyfarth Ref. No. 72178-006686 5314499932v.1Qualcomm Ref. No.2308905WO algorithms, and / or the like (collectively referred to as “elements”). These elements may be implemented using hardware, software, or combinations thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

[0023] It should be noted that while aspects may be described using terminologycommonly associated with 5G and later wireless technologies, aspects of the present disclosure can be applied in other generation-based communications systems, such as and including 3G and / or 4G technologies.

[0024] A user equipment (UE) includes a power amplifier (PA) for amplifyingcommunication signals for transmission. The power amplifier’s power consumption has a significant effect on a battery life of the UE. Reducing this power consumption by reducing a supply voltage to the power amplifier is therefore an attractive solution. Reducing the supply voltage, however, increases a non-linearity (NL) effect in the power amplifier, which introduces additive noise (e.g., a random process) to the signal. The UE’s power amplifier non-linearity is known as a radio frequency (RF) impairment that limits the achievable signal-to-noise ratio (SNR), and thus, limits the attainable data rate in the uplink (UL) channel. Thus, reducing the power consumption comes at the expense of reducing the data rate, if the non-linearity effect remains untreated. Hence, to save power without limiting the data rate, the non-linearity impairment should be estimated and removed from the uplink signal.

[0025] During the estimation process, a known pilot signal is compared to ademodulated signal, in order to examine the power amplifier input and output. That comparison yields an estimated power amplifier curve around a dynamic range of the signal power. Thus, the power amplifier estimated curve over the pilot signals will become more accurate for the data, if the dynamic range of the pilot signal, or PAPR, is similar to or larger than the dynamic range of the data. In fact, the pilot signal’s dynamic range should at least cover the transmitted data dynamic range.

[0026] According to aspects of the present disclosure, a pilot signal has a dynamicrange or PAPR that matches the data’s PAPR. Two optional pilot signals may be utilized to estimate the power amplifier model. In a first option, a dedicated uplink pilot signal, referred to as a non-linearity reference signal (NLRS), may be sent every timeSeyfarth Ref. No. 72178-006686 6314499932v.1Qualcomm Ref. No.2308905WO the power amplifier model varies. Due to the relatively low variation rate of the non- linearity random process, the pilot signal transmits at a very low rate. Thus, the overhead is negligible compared to the improved data rate resulting from non-linearity cancellation.

[0027] In a second option, a sounding reference signal (SRS) sequence is modifiedand used to estimate the power amplifier curve. The current SRS sequence has a very small dynamic range, and hence, is not appropriate for power amplifier model estimation. Even if the UE compresses the signal to operate at the non-linear region, the compressed SRS is still not an appropriate signal for estimating the power amplifier model. Aspects of the present disclosure modify the SRS sequence to a high dynamic range sequence every time the power amplifier model should be updated.

[0028] The time for updating the estimated power amplifier curve depends on atemperature variation or aging. In addition, changing the transmit power operating point or switching the transmit antenna may trigger an updated estimate. The rate of these changes is in the order of magnitude of thousands of slots. In one example, the estimate occurs every two thousand slots and the correction occurs every slot.

[0029] Particular aspects of the subject matter described in this disclosure can beimplemented to realize one or more of the following potential advantages. In some examples, the described techniques related to the non-linearity reference signal may improve communications by reducing power amplifier non-linearities during wireless transmission.

[0030] FIGURE 1 is a diagram illustrating a network 100 in which aspects of thepresent disclosure may be practiced. The network 100 may be a 5G or NR network or some other wireless network, such as an LTE network. The wireless network 100 may include a number of BSs 110 (shown as BS 110a, BS 110b, BS 110c, and BS 110d) and other network entities. A BS is an entity that communicates with user equipment (UEs) and may also be referred to as a base station, an NR BS, a Node B, a gNB, a 5G Node B, an access point, a transmit and receive point (TRP), a network node, a network entity, and / or the like. A base station can be implemented as an aggregated base station, as a disaggregated base station, an integrated access and backhaul (IAB) node, a relaynode, a sidelink node, etc. The base station can be implemented in an aggregated orSeyfarth Ref. No. 72178-006686 7314499932v.1Qualcomm Ref. No.2308905WO monolithic base station architecture, or alternatively, in a disaggregated base station architecture, and may include one or more of a central unit (CU), a distributed unit (DU), a radio unit (RU), a near-real time (near-RT) RAN intelligent controller (RIC), or a non-real time (non-RT) RIC.

[0031] Each BS may provide communications coverage for a particular geographicarea. In 3GPP, the term “cell” can refer to a coverage area of a BS and / or a BS subsystem serving this coverage area, depending on the context in which the term is used.

[0032] A BS may provide communications coverage for a macro cell, a pico cell, afemto cell, and / or another type of cell. A macro cell may cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscription. A pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs with service subscription. A femto cell may cover a relatively small geographic area (e.g., a home) and may allow restricted access by UEs having association with the femto cell (e.g., UEs in a closed subscriber group (CSG)). A BS for a macro cell may be referred to as a macro BS. A BS for a pico cell may be referred to as a pico BS. A BS for a femto cell may be referred to as a femto BS or a home BS. In the example shown in FIGURE 1, a BS 110a may be a macro BS for a macro cell 102a, a BS 110b may be a pico BS for a pico cell 102b, and a BS 110c may be a femto BS for a femto cell 102c. A BS may support one or multiple (e.g., three) cells. The terms “eNB,” “base station,” “NR BS,” “gNB,” “AP,” “Node B,” “5G NB,” “TRP,” and “cell” may be used interchangeably.

[0033] In some aspects, a cell may not necessarily be stationary, and the geographicarea of the cell may move according to the location of a mobile BS. In some aspects, the BSs may be interconnected to one another and / or to one or more other BSs or network nodes (not shown) in the wireless network 100 through various types of backhaul interfaces such as a direct physical connection, a virtual network, and / or the like using any suitable transport network.

[0034] The wireless network 100 may also include relay stations. A relay station isan entity that can receive a transmission of data from an upstream station (e.g., a BS or a UE) and send a transmission of the data to a downstream station (e.g., a UE or a BS). ASeyfarth Ref. No. 72178-006686 8314499932v.1Qualcomm Ref. No.2308905WO relay station may also be a UE that can relay transmissions for other UEs. In the example shown in FIGURE 1, a relay station 110d may communicate with macro BS 110a and a UE 120d in order to facilitate communications between the BS 110a and UE 120d. A relay station may also be referred to as a relay BS, a relay base station, a relay, and / or the like.

[0035] The wireless network 100 may be a heterogeneous network that includesBSs of different types (e.g., macro BSs, pico BSs, femto BSs, relay BSs, and / or the like). These different types of BSs may have different transmit power levels, different coverage areas, and different impact on interference in the wireless network 100. For example, macro BSs may have a high transmit power level (e.g., 5 to 40 watts) whereas pico BSs, femto BSs, and relay BSs may have lower transmit power levels (e.g., 0.1 to 2 watts).

[0036] As an example, the BSs 110 (shown as BS 110a, BS 110b, BS 110c, and BS110d) and the core network 130 may exchange communications via backhaul links 132 (e.g., S1, etc.). Base stations 110 may communicate with one another over other backhaul links (e.g., X2, etc.) either directly or indirectly (e.g., through core network 130).

[0037] The core network 130 may be an evolved packet core (EPC), which mayinclude at least one mobility management entity (MME), at least one serving gateway (S-GW), and at least one packet data network (PDN) gateway (P-GW). The MME may be the control node that processes the signaling between the UEs 120 and the EPC. All user IP packets may be transferred through the S-GW, which itself may be connected to the P-GW. The P-GW may provide IP address allocation as well as other functions. The P-GW may be connected to the network operator's IP services. The operator's IP services may include the Internet, the Intranet, an IP multimedia subsystem (IMS), and a packet-switched (PS) streaming service.

[0038] The core network 130 may provide user authentication, access authorization,tracking, IP connectivity, and other access, routing, or mobility functions. One or more of the base stations 110 or access node controllers (ANCs) may interface with the core network 130 through backhaul links 132 (e.g., S1, S2, etc.) and may perform radio configuration and scheduling for communications with the UEs 120. In someSeyfarth Ref. No. 72178-006686 9314499932v.1Qualcomm Ref. No.2308905WO configurations, various functions of each access network entity or base station 110 may be distributed across various network devices (e.g., radio heads and access network controllers) or consolidated into a single network device (e.g., a base station 110).

[0039] UEs 120 (e.g., 120a, 120b, 120c) may be dispersed throughout the wirelessnetwork 100, and each UE may be stationary or mobile. A UE may also be referred to as an access terminal, a terminal, a mobile station, a subscriber unit, a station, and / or the like. A UE may be a cellular phone (e.g., a smart phone), a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet, a camera, a gaming device, a netbook, a smartbook, an ultrabook, a medical device or equipment, biometric sensors / devices, wearable devices (smart watches, smart clothing, smart glasses, smart wrist bands, smart jewelry (e.g., smart ring, smart bracelet)), an entertainment device (e.g., a music or video device, or a satellite radio), a vehicular component or sensor, smart meters / sensors, industrial manufacturing equipment, a global positioning system device, or any other suitable device that is configured to communicate via a wireless or wired medium.

[0040] One or more UEs 120 may establish a protocol data unit (PDU) session for anetwork slice. In some cases, the UE 120 may select a network slice based on an application or subscription service. By having different network slices serving different applications or subscriptions, the UE 120 may improve its resource utilization in the wireless network 100, while also satisfying performance specifications of individual applications of the UE 120. In some cases, the network slices used by UE 120 may be served by an AMF (not shown in FIGURE 1) associated with one or both of the base station 110 or core network 130. In addition, session management of the network slices may be performed by an access and mobility management function (AMF).

[0041] The UEs 120 may include a non-linearity reference signal (NLRS) module140. For brevity, only one UE 120d is shown as including the NLRS module 140. The NLRS module 140 may transmit a request, to a network device, for transmitting a non- linearity reference signal (NLRS), in response to beginning communication with the network in a high power mode or in response to detecting variation of a non-linearity distortion model. The NLRS module 140 may also receive, from the network device, permission for uplink transmission of the non-linearity reference signal. The NLRSSeyfarth Ref. No. 72178-006686 10314499932v.1Qualcomm Ref. No.2308905WO module 140 may further transmit the non-linearity reference signal to the network device.

[0042] The core network 130 or the base stations 110 or any other network device(e.g., as seen in FIGURE 3) may include an NLRS module 138 for brevity, only one base station 110a is shown as including the NLRS module 138. The NLRS module 138 may transmit, to a user equipment (UE), permission for uplink transmission of a non- linearity reference signal (NLRS) in response to receiving, from the UE, a request for transmitting the non-linearity reference signal. The NLRS module 138 may also receive, from the UE, the non-linearity reference signal. The NLRS module 138 may further estimate a non-linearity distortion model based on receiving the non-linearity reference signal. The NLRS module 138 may still further remove a non-linearity effect from a signal received from the UE in a subsequent slot, based on the non-linearity distortion model, to obtain a corrected signal.

[0043] Some UEs may be considered machine-type communications (MTC) orevolved or enhanced machine-type communications (eMTC) UEs. MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, location tags, and / or the like, that may communicate with a base station, another device (e.g., remote device), or some other entity. A wireless node may provide, for example, connectivity for or to a network (e.g., a wide area network such as Internet or a cellular network) via a wired or wireless communication link. Some UEs may be considered Internet-of-Things (IoT) devices, and / or may be implemented as NB-IoT (narrowband internet of things) devices. Some UEs may be considered a customer premises equipment (CPE). UE 120 may be included inside a housing that houses components of UE 120, such as processor components, memory components, and / or the like.

[0044] In general, any number of wireless networks may be deployed in a givengeographic area. Each wireless network may support a particular radio access technology (RAT) and may operate on one or more frequencies. A RAT may also be referred to as a radio technology, an air interface, and / or the like. A frequency may also be referred to as a carrier, a frequency channel, and / or the like. Each frequency may support a single RAT in a given geographic area in order to avoid interference between wireless networks of different RATs. In some cases, NR or 5G RAT networks may be deployed.Seyfarth Ref. No. 72178-006686 11314499932v.1Qualcomm Ref. No.2308905WO

[0045] In some aspects, two or more UEs 120 (e.g., shown as UE 120a and UE120e) may communicate directly using one or more sidelink channels (e.g., without using a base station 110 as an intermediary to communicate with one another). For example, the UEs 120 may communicate using peer-to-peer (P2P) communications, device-to-device (D2D) communications, a vehicle-to-everything (V2X) protocol (e.g., which may include a vehicle-to-vehicle (V2V) protocol, a vehicle-to-infrastructure (V2I) protocol, and / or the like), a mesh network, and / or the like. In this case, the UE 120 may perform scheduling operations, resource selection operations, and / or other operations described elsewhere as being performed by the base station 110. For example, the base station 110 may configure a UE 120 via downlink control information (DCI), radio resource control (RRC) signaling, a media access control-control element (MAC-CE) or via system information (e.g., a system information block (SIB).

[0046] As indicated above, FIGURE 1 is provided merely as an example. Otherexamples may differ from what is described with regard to FIGURE 1.

[0047] FIGURE 2 shows a block diagram of a design 200 of the base station 110and UE 120, which may be one of the base stations and one of the UEs in FIGURE 1. The base station 110 may be equipped with T antennas 234a through 234t, and UE 120 may be equipped with R antennas 252a through 252r, where in general T ≥ 1 and R ≥ 1.

[0048] At the base station 110, a transmit processor 220 may receive data from adata source 212 for one or more UEs, select one or more modulation and coding schemes (MCS) for each UE based at least in part on channel quality indicators (CQIs) received from the UE, process (e.g., encode and modulate) the data for each UE based at least in part on the MCS(s) selected for the UE, and provide data symbols for all UEs. Decreasing the MCS lowers throughput but increases reliability of the transmission. The transmit processor 220 may also process system information (e.g., for semi-static resource partitioning information (SRPI) and / or the like) and control information (e.g., CQI requests, grants, upper layer signaling, and / or the like) and provide overhead symbols and control symbols. The transmit processor 220 may also generate reference symbols for reference signals (e.g., the cell-specific reference signal (CRS)) and synchronization signals (e.g., the primary synchronization signal (PSS) and secondary synchronization signal (SSS)). A transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on the data symbols, theSeyfarth Ref. No. 72178-006686 12314499932v.1Qualcomm Ref. No.2308905WO control symbols, the overhead symbols, and / or the reference symbols, if applicable, and may provide T output symbol streams to T modulators (MODs) 232a through 232t. Each modulator 232 may process a respective output symbol stream (e.g., for orthogonal frequency division multiplexing (OFDM) and / or the like) to obtain an output sample stream. Each modulator 232 may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. T downlink signals from modulators 232a through 232t may be transmitted via T antennas 234a through 234t, respectively. According to various aspects described in more detail below, the synchronization signals can be generated with location encoding to convey additional information.

[0049] At the UE 120, antennas 252a through 252r may receive the downlinksignals from the base station 110 and / or other base stations and may provide received signals to demodulators (DEMODs) 254a through 254r, respectively. Each demodulator 254 may condition (e.g., filter, amplify, downconvert, and digitize) a received signal to obtain input samples. Each demodulator 254 may further process the input samples (e.g., for OFDM and / or the like) to obtain received symbols. A MIMO detector 256 may obtain received symbols from all R demodulators 254a through 254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor 258 may process (e.g., demodulate and decode) the detected symbols, provide decoded data for the UE 120 to a data sink 260, and provide decoded control information and system information to a controller / processor 280. A channel processor may determine reference signal received power (RSRP), received signal strength indicator (RSSI), reference signal received quality (RSRQ), channel quality indicator (CQI), and / or the like. In some aspects, one or more components of the UE 120 may be included in a housing.

[0050] On the uplink, at the UE 120, a transmit processor 264 may receive andprocess data from a data source 262 and control information (e.g., for reports comprising RSRP, RSSI, RSRQ, CQI, and / or the like) from the controller / processor 280. Transmit processor 264 may also generate reference symbols for one or more reference signals. The symbols from the transmit processor 264 may be precoded by a TX MIMO processor 266 if applicable, further processed by modulators 254a through 254r (e.g., for discrete Fourier transform spread OFDM (DFT-s-OFDM), CP-OFDM,Seyfarth Ref. No. 72178-006686 13314499932v.1Qualcomm Ref. No.2308905WO and / or the like), and transmitted to the base station 110. At the base station 110, the uplink signals from the UE 120 and other UEs may be received by the antennas 234, processed by the demodulators 254, detected by a MIMO detector 236 if applicable, and further processed by a receive processor 238 to obtain decoded data and control information sent by the UE 120. The receive processor 238 may provide the decoded data to a data sink 239 and the decoded control information to a controller / processor 240. The base station 110 may include communications unit 244 and communicate to the core network 130 via the communications unit 244. The core network 130 may include a communications unit 294, a controller / processor 290, and a memory 292.

[0051] The controller / processor 240 of the base station 110, the controller / processor280 of the UE 120, and / or any other component(s) of FIGURE 2 may perform one or more techniques associated with NLRSs, as described in more detail elsewhere. For example, the controller / processor 240 of the base station 110, the controller / processor 280 of the UE 120, and / or any other component(s) of FIGURE 2 may perform or direct operations of, for example, the processes of FIGURES 7 and 8 and / or other processes as described. Memories 242 and 282 may store data and program codes for the base station 110 and UE 120, respectively. A scheduler 246 may schedule UEs for data transmission on the downlink and / or uplink.

[0052] In some aspects, the UE 120 and / or base station 110 may include means forreceiving, means for transmitting, means for receiving, means for learning, means for estimating, means for removing, and means for determining. Such means may include one or more components of the UE 120 or base station 110 described in connection with FIGURE 2.

[0053] As indicated above, FIGURE 2 is provided merely as an example. Otherexamples may differ from what is described with regard to FIGURE 2.

[0054] Deployment of communication systems, such as 5G new radio (NR)systems, may be arranged in multiple manners with various components or constituent parts. In a 5G NR system, or network, a network node, a network entity, a mobility element of a network, a radio access network (RAN) node, a core network node, a network element, or a network equipment, such as a base station (BS), or one or more units (or one or more components) performing base station functionality, may beSeyfarth Ref. No. 72178-006686 14314499932v.1Qualcomm Ref. No.2308905WO implemented in an aggregated or disaggregated architecture. For example, a BS (such as a Node B (NB), an evolved NB (eNB), an NR BS, 5G NB, an access point (AP), a transmit and receive point (TRP), or a cell, etc.) may be implemented as an aggregated base station (also known as a standalone BS or a monolithic BS) or a disaggregated base station.

[0055] An aggregated base station may be configured to utilize a radio protocol stackthat is physically or logically integrated within a single RAN node. A disaggregated base station may be configured to utilize a protocol stack that is physically or logically distributed among two or more units (such as one or more central or centralized units (CUs), one or more distributed units (DUs), or one or more radio units (RUs)). In some aspects, a CU may be implemented within a RAN node, and one or more DUs may be co-located with the CU, or alternatively, may be geographically or virtually distributed throughout one or multiple other RAN nodes. The DUs may be implemented to communicate with one or more RUs. Each of the CU, DU, and RU also can be implemented as virtual units (e.g., a virtual central unit (VCU), a virtual distributed unit (VDU), or a virtual radio unit (VRU)).

[0056] Base station-type operations or network designs may consider aggregationcharacteristics of base station functionality. For example, disaggregated base stations may be utilized in an integrated access backhaul (IAB) network, an open radio access network (O-RAN (such as the network configuration sponsored by the O-RAN Alliance)), or a virtualized radio access network (vRAN, also known as a cloud radio access network (C-RAN)). Disaggregation may include distributing functionality across two or more units at various physical locations, as well as distributing functionality for at least one unit virtually, which can enable flexibility in network design. The various units of the disaggregated base station, or disaggregated RAN architecture, can be configured for wired or wireless communication with at least one other unit.

[0057] In some cases, different types of devices supporting different types ofapplications and / or services may coexist in a cell. Examples of different types of devices include UE handsets, customer premises equipment (CPEs), vehicles, Internet of Things (IoT) devices, and / or the like. Examples of different types of applications include ultra-reliable low-latency communications (URLLC) applications, massive machine-type communications (mMTC) applications, enhanced mobile broadbandSeyfarth Ref. No. 72178-006686 15314499932v.1Qualcomm Ref. No.2308905WO (eMBB) applications, vehicle-to-anything (V2X) applications, and / or the like. Furthermore, in some cases, a single device may support different applications or services simultaneously.

[0058] FIGURE 3 shows a diagram illustrating an example disaggregated base station300 architecture. The disaggregated base station 300 architecture may include one or more central units (CUs) 310 that can communicate directly with a core network 320 via a backhaul link, or indirectly with the core network 320 through one or more disaggregated base station units (such as a near-real time (near-RT) RAN intelligent controller (RIC) 325 via an E2 link, or a non-real time (non-RT) RIC 315 associated with a service management and orchestration (SMO) framework 305, or both). A CU 310 may communicate with one or more distributed units (DUs) 330 via respective midhaul links, such as an F1 interface. The DUs 330 may communicate with one or more radio units (RUs) 340 via respective fronthaul links. The RUs 340 may communicate with respective UEs 120 via one or more radio frequency (RF) access links. In some implementations, the UE 120 may be simultaneously served by multiple RUs 340.

[0059] Each of the units (e.g., the CUs 310, the DUs 330, the RUs 340, as well as thenear-RT RICs 325, the non-RT RICs 315, and the SMO framework 305) may include one or more interfaces or be coupled to one or more interfaces configured to receive or transmit signals, data, or information (collectively, signals) via a wired or wireless transmission medium. Each of the units, or an associated processor or controller providing instructions to the communication interfaces of the units, can be configured to communicate with one or more of the other units via the transmission medium. For example, the units can include a wired interface configured to receive or transmit signals over a wired transmission medium to one or more of the other units. Additionally, the units can include a wireless interface, which may include a receiver, a transmitter or transceiver (such as a radio frequency (RF) transceiver), configured to receive or transmit signals, or both, over a wireless transmission medium to one or more of the other units.

[0060] In some aspects, the CU 310 may host one or more higher layer controlfunctions. Such control functions can include radio resource control (RRC), packet data convergence protocol (PDCP), service data adaptation protocol (SDAP), or the like.Seyfarth Ref. No. 72178-006686 16314499932v.1Qualcomm Ref. No.2308905WO Each control function can be implemented with an interface configured to communicate signals with other control functions hosted by the CU 310. The CU 310 may be configured to handle user plane functionality (e.g., central unit – user plane (CU-UP)), control plane functionality (e.g., central unit – control Plane (CU-CP)), or a combination thereof. In some implementations, the CU 310 can be logically split into one or more CU-UP units and one or more CU-CP units. The CU-UP unit can communicate bi- directionally with the CU-CP unit via an interface, such as the E1 interface when implemented in an O-RAN configuration. The CU 310 can be implemented to communicate with the DU 330, as necessary, for network control and signaling.

[0061] The DU 330 may correspond to a logical unit that includes one or more basestation functions to control the operation of one or more RUs 340. In some aspects, the DU 330 may host one or more of a radio link control (RLC) layer, a medium access control (MAC) layer, and one or more high physical (PHY) layers (such as modules for forward error correction (FEC) encoding and decoding, scrambling, modulation and demodulation, or the like) depending, at least in part, on a functional split, such as those defined by the Third Generation Partnership Project (3GPP). In some aspects, the DU 330 may further host one or more low PHY layers. Each layer (or module) can be implemented with an interface configured to communicate signals with other layers (and modules) hosted by the DU 330, or with the control functions hosted by the CU 310.

[0062] Lower-layer functionality can be implemented by one or more RUs 340. Insome deployments, an RU 340, controlled by a DU 330, may correspond to a logical node that hosts RF processing functions, or low-PHY layer functions (such as performing fast Fourier transform (FFT), inverse FFT (iFFT), digital beamforming, physical random access channel (PRACH) extraction and filtering, or the like), or both, based at least in part on the functional split, such as a lower layer functional split. In such an architecture, the RU(s) 340 can be implemented to handle over the air (OTA) communication with one or more UEs 120. In some implementations, real-time and non-real-time aspects of control and user plane communication with the RU(s) 340 can be controlled by the corresponding DU 330. In some scenarios, this configuration can enable the DU(s) 330 and the CU 310 to be implemented in a cloud-based RAN architecture, such as a vRAN architecture.Seyfarth Ref. No. 72178-006686 17314499932v.1Qualcomm Ref. No.2308905WO

[0063] The SMO framework 305 may be configured to support RAN deployment andprovisioning of non-virtualized and virtualized network elements. For non-virtualized network elements, the SMO framework 305 may be configured to support the deployment of dedicated physical resources for RAN coverage requirements, which may be managed via an operations and maintenance interface (such as an O1 interface). For virtualized network elements, the SMO framework 305 may be configured to interact with a cloud computing platform (such as an open cloud (O-cloud) 390) to perform network element life cycle management (such as to instantiate virtualized network elements) via a cloud computing platform interface (such as an O2 interface). Such virtualized network elements can include, but are not limited to, CUs 310, DUs 330, RUs 340, and near-RT RICs 325. In some implementations, the SMO framework 305 can communicate with a hardware aspect of a 4G RAN, such as an open eNB (O- eNB) 311, via an O1 interface. Additionally, in some implementations, the SMO framework 305 can communicate directly with one or more RUs 340 via an O1 interface. The SMO framework 305 also may include a non-RT RIC 315 configured to support functionality of the SMO framework 305.

[0064] The non-RT RIC 315 may be configured to include a logical function thatenables non-real-time control and optimization of RAN elements and resources, artificial intelligence / machine learning (AI / ML) workflows including model training and updates, or policy-based guidance of applications / features in the near-RT RIC 325. The non-RT RIC 315 may be coupled to or communicate with (such as via an A1 interface) the near-RT RIC 325. The near-RT RIC 325 may be configured to include a logical function that enables near-real-time control and optimization of RAN elements and resources via data collection and actions over an interface (such as via an E2 interface) connecting one or more CUs 310, one or more DUs 330, or both, as well as the O-eNB 311, with the near-RT RIC 325.

[0065] In some implementations, to generate AI / ML models to be deployed in thenear-RT RIC 325, the non-RT RIC 315 may receive parameters or external enrichment information from external servers. Such information may be utilized by the near-RT RIC 325 and may be received at the SMO framework 305 or the non-RT RIC 315 from non-network data sources or from network functions. In some examples, the non-RT RIC 315 or the near-RT RIC 325 may be configured to tune RAN behavior orSeyfarth Ref. No. 72178-006686 18314499932v.1Qualcomm Ref. No.2308905WO performance. For example, the non-RT RIC 315 may monitor long-term trends and patterns for performance and employ AI / ML models to perform corrective actions through the SMO framework 305 (such as reconfiguration via O1) or via creation of RAN management policies (such as A1 policies).

[0066] A UE includes a power amplifier (PA) for amplifying communicationsignals for transmission. The power amplifier’s power consumption has a significant effect on the UE’s battery life. Reducing this power consumption by reducing a supply voltage to the power amplifier is therefore an attractive solution and is of high interest for future standards releases, including Green Networks. Reducing the supply voltage, however, increases a non-linearity (NL) effect in the power amplifier, which introduces additive noise (e.g., a random process) to the signal. The UE’s power amplifier non- linearity is known as a radio frequency (RF) impairment that limits the achievable signal-to-noise ratio (SNR), and thus, limits the attainable data rate in the uplink (UL) channel. Thus, reducing the power consumption comes at the expense of reducing the data rate, if the non-linearity effect remains untreated. Hence, to save power without limiting the data rate, the non-linearity impairment should be estimated and removed from the uplink signal.

[0067] Estimating and the correcting a non-linearity can be performed at the UE ortransmitter (Tx) side (for example, with a digital pre-distortion (DPD) technique) or at the network (e.g., base station (gNB)) or receiver (Rx) side (for example, with a digital post-distortion (DPoD) technique). The network side estimation and correction may be preferable because it is desirable to reduce the UE power consumption and also to reduce the UE complexity. DPD involves high complexity because of the required extra analog chain for closed loop feedback.

[0068] In the DPoD technique, the receiver estimates a power amplifier modeliteratively with the channel, assisted by the pilot signals, in other words, DPoD on the pilot signal results in the estimate. Afterwards, data (e.g., the physical downlink shared channel (PDSCH)) is corrected by applying the estimated power amplifier model on the received equalized data (e.g., DPoD on the PDSCH results in the correction).

[0069] At the estimation process, the known pilot signal is compared to thedemodulated signal, in order to examine the power amplifier input and output. ThatSeyfarth Ref. No. 72178-006686 19314499932v.1Qualcomm Ref. No.2308905WO comparison yields the estimated power amplifier curve around the dynamic range of the signal power. Thus, the power amplifier estimated curve over the pilot signals will become more accurate for the data, if the dynamic range of the pilot signal, or PAPR, is similar to or larger than the dynamic range of the data. In fact, the pilot signal’s dynamic range should at least cover the transmitted data dynamic range.

[0070] FIGURES 4A to 4D are graphs illustrating transmitted data samples andpilot signals, in accordance with various aspects of the present disclosure. The graphs of FIGURE 4A to FIGURE 4D illustrate the importance of matching the dynamic range of the data and the pilot signal. Each of the graphs shows an example of a power amplifier model curve (e.g., based on the Rapp model).

[0071] FIGURE 4A depicts transmitted data samples. As FIGURE 4A shows, thedynamic range of data samples 405 is within both linear and the non-linear regions 402, 404. Hence, to estimate the power amplifier model, a signal with at least the same dynamic range or PAPR is desired.

[0072] FIGURE 4B depicts a pilot signal 410 with a small dynamic range or lowPAPR in the linear region 402. A power amplifier model estimation cannot be based on the specific pilot sequence samples 410, because the receiver can estimate only the linear region 402, which is insufficient to estimate the distortion that the data samples 405 in FIGURE 4A experience.

[0073] This problem may be resolved by suggesting that the UE may increase thepower in order to have a compressed pilot signal 415 that indicates the distortion in the non-linear region 404, such as seen in FIGURE 4C. However, estimating based on the compressed pilot signal 415 will be poor because the receiver cannot estimate the linear region 402 and the estimated power amplifier curve will again be inaccurate for the data samples 405.

[0074] FIGURE 4D depicts suggested pilot signals 420, according to aspects of thepresent disclosure. A dynamic range of the suggested pilot signals 420 is similar to or greater than the transmitted data dynamic range, and hence, a power amplifier model estimation aided by those suggested pilot signals 420 is more accurate for the data samples 405, in contrast to the previous two pilot signals 410, 415 of FIGURES 4B and 4C, respectively.Seyfarth Ref. No. 72178-006686 20314499932v.1Qualcomm Ref. No.2308905WO

[0075] In conclusion, a pilot signal with a small dynamic range sequence results inpoor performance for any power amplifier model regardless of the operating point. The estimated power amplifier curve based on a signal with a small dynamic range is based on extrapolation, while the estimate based on a pilot signal with a proper dynamic range is based on interpolation. Thus, the pilot signal’s dynamic range should be equal to or greater than the data dynamic range of the data samples in order to yield an accurate power amplifier model correction.

[0076] According to aspects of the present disclosure, a pilot signal has a dynamicrange or PAPR that matches the data’s PAPR. A traditional approach utilizes a demodulation reference signal (DMRS) as a pilot for the DPoD process. However, such selection is not desirable for several reasons. The DMRS pilot is usually precoded before it passes the power amplifier. The pilot streams are multiplied by a precoding matrix. In order to estimate the power amplifier model at the network side, the UE provides the precoder information, to the network, to reconstruct the power amplifier input at the network side. Thus, utilizing the DMRS for non-linearity estimation incurs a high overhead when transmitting over the uplink the precoder(s) data. Another concern is the requirement of a proper dynamic range. There is no guarantee that the DMRS has the proper dynamic range as depicted in FIGURES 4A-4C. Yet another disadvantage is the relative high rate of the DMRS transmission. The DMRS is sent in every slot, while the variation of the non-linearity random process is much slower.

[0077] Another solution for correcting non-linearities is to utilize the soundingreference signal (SRS) as a pilot for the DPoD process. The SRS does not have all of the disadvantages of the DMRS. That is, the SRS is not precoded, and thus, the precoder transmission overhead is saved. In addition, the SRS transmission rate is much lower, such as once in channel coherence time, compared to the DMRS transmission every slot. However, the SRS sequence (e.g., Zadoff-Chu (ZC)) cannot be used to estimate the power amplifier model due to its very small dynamic range. The ZC sequence is known by its ~0dB peak-to-average power ratio (PAPR), and hence, the ZC sequence has a limited dynamic range.

[0078] Conventional wireless communications systems do not specify dedicatedsignaling for estimating, on the uplink, the non-linearity distortion of the UE. Moreover, conventional wireless communications systems do not specify an optimalSeyfarth Ref. No. 72178-006686 21314499932v.1Qualcomm Ref. No.2308905WO policy for the non-linearity estimation distortion rate with regard to its variation rate. Aspects of the present disclosure solve these two issues by allocating a special pilot signal, referred to as a non-linearity reference signal (NLRS). Aspects also include independently detecting the UE’s non-linearity distortion variation, and hence, a need for a refresh, both at the network and UE sides.

[0079] According to aspects of the present disclosure, two optional pilot signals canbe utilized to estimate the power amplifier model. A dedicated uplink pilot signal, referred to as an NLRS, may be sent every time the power amplifier model varies. Due to the relatively low variation rate of the non-linearity random process, the pilot signal transmits at a very low rate. Thus, the overhead is negligible compared to the improved data rate resulting from non-linearity cancellation.

[0080] For example, consider the case when the non-linearity limits the noise floorto -30 decibels relative to the carrier (dBc) and it varies approximately every second in a sub 6 GHz numerology (e.g., 100 MHz bandwidth) with a high SNR. The modulation and coding scheme (MCS) is limited to 256 quadrature amplitude modulation (QAM) (in some code rate) if the non-linearity is not treated. In other words, the number of bits per second is (QAM 256 rate 0.9): (slots per second) * (OFDM symbols per slot) * (resource elements (REs) per OFDM symbol) * (uncoded bits per RE) = = 0.5661x10^9 = 566 Mbps.

[0081] If the non-linearity is corrected, the communications incur an overhead of 1OFDM (4.1278x10^4 = 41 Kbps) symbol but the modulation can be increased up to 16K QAM. That is, the number of bits per second is (QAM 16384 rate 0.9): (slots per second) * (OFDM symbols per slot) * (REs per OFDM symbols) * (uncoded bits per RE) = 2000 * 12 * 3276 * 14 *0.9 = 0.9907x10^9 = 990 Mbps.

[0082] Thus, the non-linearity reference signal (NLRS) overhead is negligiblecompared to the large throughput gain (e.g., 556 Mbps vs.990 Mbps) with a negligible penalty of 41 Kbps.

[0083] In other aspects, the SRS sequence is modified and used to estimate thepower amplifier curve. The current SRS sequence has a very small dynamic range (as shown in FIGURE 4B), and hence, is not appropriate for power amplifier model estimation. Even if the UE compresses the signal to operate at the non-linear region (asSeyfarth Ref. No. 72178-006686 22314499932v.1Qualcomm Ref. No.2308905WO shown in FIGURE 4C), the compressed SRS is still not appropriate for estimating the power amplifier model. Aspects of the present disclosure modify the SRS sequence to a high dynamic range sequence every time the power amplifier model should be updated.

[0084] The time for updating depends on a temperature variation or aging (e.g., timesince a last update). In addition, changing the transmit power operating point or switching the transmit antenna triggers an updated estimate. The rate of these changes is in the order of magnitude of thousands of slots. In one example, the estimate occurs every two thousand slots and the correction occurs every slot.

[0085] The generation of such a sequence may be based in the time domain (TD)and an inverse fast Fourier transform (IFFT) may then be performed to fit the sequence to the frequency domain representation of the orthogonal frequency division multiplexing (OFDM) slot. In other implementations, many random sequences are generated offline in the frequency domain and a sequence is selected with a time domain PAPR sufficiently high to match the PDSCH’s PAPR, for example, 12 dB.

[0086] FIGURE 5 is a call flow diagram illustrating communications related to anon-linearity reference signal (NLRS), in accordance with various aspects of the present disclosure. In the example of FIGURE 5, a UE 120 communicates with a network device, such as a base station 110. At time t1, the UE 120 sends a request, to the base station 110, for transmitting an NLRS. The UE 120 sends the request to the base station 110 over the uplink. The request may be sent in two cases. The first case arises at the beginning of the communication, if the UE 120 is operating at a high transmit power operation point with regards to the voltage supply. Each UE 120 may set a threshold power for the power supply that determines when to send the request. The second case arises if the UE 120 concludes that the non-linearity distortion model has varied, and the non-linearity distortion estimation should be updated. The UE 120 may send the request over the physical uplink control channel (PUCCH). In some implementations, the request consists of only one bit indicating if the non-linearity estimate needs an update.

[0087] At time t2, the base station 110 sends permission for uplink transmission ofthe NLRS. The base station 110 schedules the uplink transmission of the NLRS in response to the UE’s request at time t1. The network informs the UE 120 over theSeyfarth Ref. No. 72178-006686 23314499932v.1Qualcomm Ref. No.2308905WO physical downlink control channel (PDCCH) in downlink control information (DCI) of which upcoming slot the UE 120 can send the NLRS. As noted above, the UE 120 can modify the SRS, increasing its dynamic range, in order to estimate the non-linearity (NL) distortion or transmit a dedicated pilot signal for the NLRS. The base station 110 decides which of those two methods should be used and informs the UE 120 accordingly.

[0088] At time t3, the UE 120 sends the NLRS. The UE 120 sends the NLRS pilotor changes the SRS according to the base station 110 command received at time t2.

[0089] At time t4, the base station 110 estimates the power amplifier model basedon the received NLRS. The base station 110 estimates the power amplifier model with any type of power amplifier model estimation method, for example, DPoD. If the UE 120 transmitted the SRS, the base station 110 iteratively estimates the non-linearity together with the channel, from the same pilot signal. If the UE 120 transmits a dedicated signal, the base station 110 estimates the non-linearity separately from the channel. That is, the base station 110 first estimates the channel based on the SRS.

[0090] At time t5, the base station 110 removes the non-linearity effect from thenext slots, for example, in the physical uplink shared channel (PUSCH). The non- linearity removal occurs every slot. An example of how to implement removal is later described.

[0091] At times t6a and t6b, the base station 110 and UE 120 determine if anupdated power amplifier model is desired. Each side may conclude, based on its observations, if the non-linearity estimate should be updated. For the base station side, the base station 110 can determine whether the non-linearity estimation should be updated based on whether the corrected signal’s spectrum (after non-linearity correction) is still compressed.

[0092] FIGURE 6 is a power spectral density graph of compressed anduncompressed signals, in accordance with various aspects of the present disclosure. In the example of FIGURE 6, a compressed signal 602 and an uncompressed signal 604 are shown. The compressed signal 602 includes regions 610. Thus, the compressed signal 602 can be distinguished from the uncompressed signal 604.Seyfarth Ref. No. 72178-006686 24314499932v.1Qualcomm Ref. No.2308905WO

[0093] The base station 110 may also check if an error vector magnitude (EVM) ofa current slot is significantly degraded compared to a previous slot. If so, a non- linearity estimate may be desired. If the base station 110 detects a non-linearity variation, the process returns to the operations at time t2 (of FIGURE 5). If the base station 110 requests the UE 120 to change transmission power, the process also returns to the operations at time t2.

[0094] For UE detection, the UE 120 may determine whether a non-linearityestimate should be updated based on whether the UE’s temperature changed by more than T degrees compared to a previous temperature measurement. If one of the UE transmit antennas has changed, the UE 120 may request an updated power amplifier non-linearity estimate in each of N slots regardless of temperature variation. The two parameters, T, N, may be learned offline. If the UE 120 detects a non-linearity variation, the UE 120 returns to the operations at time t1.

[0095] Details are now provided of exemplary channel and non-linearity modelestimation based on the modified SRS. First, the base station utilizes the SRS in order to estimate the channel and the noise. Due to the non-linearity impairment of the observed signal, the initial channel estimation might be relatively inaccurate. Next, the base station applies the estimated channel on the SRS pilots. Afterwards, the base station performs a power amplifier model estimation to find the UE’s power amplifier model coefficients, by comparing the observed signal with the generated signal. Then, the base station subtracts the estimated non-linearity impairment from the observed signal. The base station then repeats the entire process for several iterations until a satisfactory error is achieved on the SRS pilots.

[0096] For separate non-linearity and channel estimation, the base station estimatesthe channel based on the SRS and the non-linearity distortion based on the NLRS. Due to the small dynamic range of the original SRS, the SRS does not experience any non- linearity distortion and thus, the channel estimation will not be impaired. The estimating can be performed by any known channel estimation methods. Otherwise, if the SRS is compressed, the base station may add the impairment to the SRS pilot. To perform the channel estimation in the presence of non-linearity, instead of comparing the received signal to the DMRS for the data sample, ^^^^^^^^^^, the received signal is compared to the non-linearity impaired DMRS assisted by the power amplifier modelSeyfarth Ref. No. 72178-006686 25314499932v.1Qualcomm Ref. No.2308905WOcoefficients. In other words, compare ^^^^^^^^^^ = ^^(^^^^^^^^^^ + ^^^^(^^^^^^^^^^)) +^^ to ^^^^^^^^^^ + ^^^^(^^^^^^^^^^), where ^^ is the channel, ^^^^^^^^^^ is the estimated receivedDMRS signal, ^^^^^^^^^^is the transmitted DMRS signal, and ^^ represents noise. For the non-linearity estimate ^^^^(), based on the NLRS, the base station may perform any known method of non-linearity estimation.

[0097] The physical uplink shared channel (PUSCH) correction may be performediteratively. For example, a regular iterative DPoD process may be performed on the PDSCH, which is the correction of data affected by a non-linearity impairment. First, the UE equalizes the received signal by utilizing the estimated channel and noise. Second, the UE applies a hard slicer on the equalized data. Third, the UE applies the estimated non-linearity impairment on the slicer output. Fourth, the UE applies the channel on the previous step output. Fifth, the UE subtracts the non-linearity expression from the received signal. Finally, the process returns to the first step.

[0098] An example of a power amplifier model and channel estimation is nowdescribed. The non-linearity (NL) impairment can be represented as an infinite oddpolynomial expression: ^^^^(^^(^^)) = ∑∞ ^^=0 ^^^^^^|^^|2(^^+1) , where ^^^^represents the nth power amplifier coefficientmodel, and ^^ represents the transmitted data, e.g., the power amplifier inputs. Once the {^^^^}^^^^=0values are estimated, the assumed PA model can be reconstructed. The above model assumes no memory terms, however, if memory components are present, the above expression might consist of similar components, as follows: ^^[^^] ∙ |^^[^^ − ^^1]|2 , ^^[^^] ∙ ^^[^^ − ^^2] ∗ ^^^^^^^^(^^[^^ − ^^2]), ^^[^^] ∙ |^^[^^ − ^^3]|,where ^^^^represents the time delay of the components, and ^^^^^^^^ represents the conjugate operator that flips the sign of the imaginary part of the complex number.

[0099] The DPoD technique aims to estimate the non-linearity characteristics ineach transmit antenna as a finite degree polynomial. For example, the power amplifiercharacteristics can be approximated by ^^^^^^(^^) ≈ ∑^ ^^^ =0 ^^^^,^^^^|^^|2(^^+1) , where ^^ represents a transmit antenna index andset. Thus, ^^ estimating the non-linearity coefficients {^^^^,^^}^^=0for each transmit antenna “^^” yields the estimation of the corresponding NL distortion. For simplicity, the estimation andSeyfarth Ref. No. 72178-006686 26314499932v.1Qualcomm Ref. No.2308905WO the correction of the NL are represented for a single-input single-output (SISO)communication system and ^^ = 2, e.g., the parameters’ set is {^^^^} 2^^=0 = {^^0, ^^1, ^^2}.The estimation model can be easily enhanced for a multiple-input, multiple-output(MIMO) system, for ^^ > 2, or for an estimation that also consists of memorycomponents.

[0100] The observed signal ^^(^^), with the non-linearity impairment, can beapproximated by the following polynomial model: ^^(^^) = ℎ(^^) ∗ (^^(^^) + ^^^^ (^^(^^)) = ℎ(^^) ∗ ^^(^^) + ℎ(^^) ∗ ∑^^ ^^=0 ^^^^^^|^^|2(^^+1) + ^^^^^^^^^^) representthe time domain representations of the channel, the transmitted signal, and the non- linearity distortion, respectively.

[0101] For ^^ = 2:^^(^^) = ℎ(^^) ∗ [^^(^^) + ^^1^^(^^)|^^(^^)|2 + ^^2^^(^^)|^^(^^)|4 + ^^3^^(^^)|^^(^^)|6]+^^^^^^^^^^(^^).

[0102] From the first step, the estimated channel ℎ (^^) is obtained from the SRS orfrom the NLRS. In the second step described above, where the base station applies the estimated channel on the SRS pilots, the base station applies the estimated channel onthe pilot signals to generate ℎ (^^) ∗ ^^(^^). Then, the base station subtracts ℎ (^^) ∗ ^^(^^)from the observed signal ^^(^^) to generate the observed NL impairment after the channelinfluence ^^(^^), where ^^(^^) = ^^(^^) − ℎ (^^) ∗ ^^(^^).

[0103] that:^^(^^) − ℎ (^^) ∗ ^^(^^) = ^^0 ℎ (^^) ∗ ^^(^^)|^^(^^)|2+c1 ℎ (^^) ∗ ^^(^^)|^^(^^)|4+c2 ℎ (^^) ∗ ^^|^^|6+where {^^^^(^^)}2^^=0represents a power amplifier’s estimated polynomial components after the channel influence.

[0104] More precisely, assuming that ^^(^^) includes N samples:Seyfarth Ref. No. 72178-006686 27314499932v.1Qualcomm Ref. No.2308905WO ^^(0) ^^0(0) ^^1(0) ^^2(0) ^^ ^^^^^^^^^^(0) [ ^^(1)] = [^^ (1) ^00^1(1) ^^2(1) ] [ ^^1]+ [^^^^^^^^^^(1) ]. 1)

[00105] us, e eas squares es ma or s g ven by:^^ = [^̂^0 , ^̂^1 , ^̂^2] = (^^ ^^^^)−1^^^^ ∙ ^^(^^).

[0106] Afterlinearity estimator isgiven by ^^^^ (^^(^^)) = ∑2 ^^=0 ^̂^^^^^(^^)|^^(^^)|2(^^+1) .

[0107] After that estimation is obtained, ^^^^^^^^^^^^^^^^^^^^(^^) = ^^(^^) − ℎ (^^) ∗ ^^^^ (^^(^^)).Then, the channel estimation is performed

[0108] As indicated above, FIGURES 3-6 are provided as examples. Otherexamples may differ from what is described with respect to FIGURES 3-6.

[0109] FIGURE 7 is a flow diagram illustrating an example process 700 performed,for example, by a user equipment (UE), in accordance with various aspects of the present disclosure. The example process 700 is an example of processing a high dynamic range reference signal (RS) for estimating and correcting non-linearities in a power amplifier (PA) of a user equipment (UE). The operations of the process 700 may be implemented by a UE 120.

[0110] At block 702, the user equipment (UE) transmits a request, to a networkdevice, for transmitting a non-linearity reference signal (NLRS), in response to beginning communication with the network in a high power mode or in response to detecting variation of a non-linearity distortion model. For example, the UE (e.g., using the antenna 252, DEMOD / MOD 254, TX MIMO processor 266, transmit processor 264, controller / processor 280, memory 282, and / or the like) may transmit the request. In some aspects, the UE may detect variation of the non-linearity distortion model by detecting a UE temperature change exceeding a first threshold, detecting a transmit antenna change, and / or determining a quantity of slots since transmitting the request exceeds a second threshold.Seyfarth Ref. No. 72178-006686 28314499932v.1Qualcomm Ref. No.2308905WO

[0111] At block 704, the user equipment (UE) receives, from the network device,permission for uplink transmission of the non-linearity reference signal. For example, the UE (e.g., using the antenna 252, DEMOD / MOD 254, MIMO detector 256, receive processor 258, controller / processor 280, memory 282, and / or the like) may receive the permission. The permission may indicate a type of the non-linearity reference signal, and a slot for transmitting the non-linearity reference signal.

[0112] At block 706, the user equipment (UE) transmits the non-linearity referencesignal to the network device. For example, the UE (e.g., using the antenna 252, DEMOD / MOD 254, TX MIMO processor 266, transmit processor 264, controller / processor 280, memory 282, and / or the like) may transmit the non-linearity reference signal. In some aspects, the non-linearity reference signal comprises a dedicated pilot signal. In other aspects, the non-linearity reference signal comprises an increased dynamic range sounding reference signal (SRS).

[0113] FIGURE 8 is a flow diagram illustrating an example process 800 performed,for example, by a network device, in accordance with various aspects of the present disclosure. The example process 800 is an example of processing a high dynamic range reference signal (RS) for estimating and correcting non-linearities in a power amplifier (PA) of a user equipment (UE). The operations of the process 800 may be implemented by a base station 110.

[0114] At block 802, the base station transmits, to a user equipment (UE),permission for uplink transmission of a non-linearity reference signal (NLRS) in response to receiving, from the UE, a request for transmitting the non-linearity reference signal. For example, the base station (e.g., using the antenna 234, MOD / DEMOD 232, TX MIMO processor 230, transmit processor 220, controller / processor 240, memory 242, and / or the like) may transmit the permission. The permission may indicate a type of the non-linearity reference signal, and a slot for transmitting the non-linearity reference signal.

[0115] At block 804, the base station receives, from the UE, the non-linearityreference signal. For example, the base station (e.g., using the antenna 234, MOD / DEMOD 232, MIMO detector 236, receive processor 238, controller / processor 240, memory 242, and / or the like) may receive the non-linearity reference signal. InSeyfarth Ref. No. 72178-006686 29314499932v.1Qualcomm Ref. No.2308905WO some aspects, the non-linearity reference signal comprises a dedicated pilot signal. In other aspects, the non-linearity reference signal comprises an increased dynamic range sounding reference signal (SRS).

[0116] At block 806, the base station estimates a non-linearity distortion modelbased on receiving the non-linearity reference signal. For example, the base station (e.g., using the controller / processor 240, memory 242, and / or the like) may estimate the non-linearity distortion model. At block 808, the base station removes a non-linearity effect from a signal received from the UE in a subsequent slot, based on the non- linearity distortion model, to obtain a corrected signal. For example, the base station (e.g., using the controller / processor 240, memory 242, and / or the like) may remove the non-linearity effect. Example Aspects

[0117] Aspect 1: A method of wireless communication by a user equipment (UE),comprising: transmitting a request, to a network device, for transmitting a non-linearity reference signal (NLRS), in response to beginning communication with the network in a high power mode or in response to detecting variation of a non-linearity distortion model; receiving, from the network device, permission for uplink transmission of the non-linearity reference signal; and transmitting the non-linearity reference signal to the network device.

[0118] Aspect 2: The method of Aspect 1, in which the non-linearity referencesignal comprises a dedicated pilot signal.

[0119] Aspect 3: The method of Aspect 1, in which transmitting the non-linearityreference signal comprises increasing a dynamic range of a sounding reference signal (SRS).

[0120] Aspect 4: The method of any of the preceding Aspects, in which thepermission indicates a type of the non-linearity reference signal, and a slot for transmitting the non-linearity reference signal.

[0121] Aspect 5: The method of any of the preceding Aspects, in which detectingvariation of the non-linearity distortion model comprises at least one of: detecting a UE temperature change exceeding a first threshold, detecting a transmit antenna change, orSeyfarth Ref. No. 72178-006686 30314499932v.1Qualcomm Ref. No.2308905WO determining a quantity of slots since transmitting the request exceeds a second threshold.

[0122] Aspect 6: The method of any of the preceding Aspects, further comprisinglearning the first threshold and the second threshold offline.

[0123] Aspect 7: A method of wireless communication by a network device,comprising: transmitting, to a user equipment (UE), permission for uplink transmission of a non-linearity reference signal (NLRS) in response to receiving, from the UE, a request for transmitting the non-linearity reference signal; receiving, from the UE, the non-linearity reference signal; estimating a non-linearity distortion model based on receiving the non-linearity reference signal; and removing a non-linearity effect from a signal received from the UE in a subsequent slot, based on the non-linearity distortion model, to obtain a corrected signal.

[0124] Aspect 8: The method of Aspect 7, in which the non-linearity referencesignal comprises a dedicated pilot signal and the estimating of the non-linearity distortion model occurs separately from estimating a channel between the UE and the network device.

[0125] Aspect 9: The method of Aspect 7, in which the non-linearity referencesignal comprises a sounding reference signal (SRS) having an increased dynamic range, and the estimating of the non-linearity distortion model occurs iteratively with jointly estimating a channel between the UE and the network device.

[0126] Aspect 10: The method of any of the Aspects 7-9, in which the permissionindicates a type of the non-linearity reference signal, and a slot for transmitting the non- linearity reference signal.

[0127] Aspect 11: The method of any of the Aspects 7-10, further comprisingdetermining the non-linearity distortion model should be updated based on at least one of: determining whether a spectrum of the corrected signal is compressed, or determining a current quality of a current slot is a threshold level below a past quality of a past slot.Seyfarth Ref. No. 72178-006686 31314499932v.1Qualcomm Ref. No.2308905WO

[0128] Aspect 12: The method of any of the Aspects 7-11, in which the currentquality of the current slot comprises a current error vector magnitude (EVM) of the current slot.

[0129] Aspect 13: An apparatus for wireless communication, comprising: at leastone memory; and at least one processor coupled to the at least one memory, the at least one processor configured: to transmit a request, to a network device, for transmitting a non-linearity reference signal (NLRS), in response to beginning communication with the network in a high power mode or in response to detecting variation of a non- linearity distortion model; to receive, from the network device, permission for uplink transmission of the non-linearity reference signal; and to transmit the non-linearity reference signal to the network device.

[0130] Aspect 14: The apparatus of Aspect 13, in which the non-linearity referencesignal comprises a dedicated pilot signal.

[0131] Aspect 15: The apparatus of Aspect 13, in which the at least one processoris further configured to increase a dynamic range of a sounding reference signal (SRS).

[0132] Aspect 16: The apparatus of any of the Aspects 13-15, in which thepermission indicates a type of the non-linearity reference signal, and a slot for transmitting the non-linearity reference signal.

[0133] Aspect 17: The apparatus of any of the Aspects 13-16, in which the at leastone processor is further configured to detect a UE temperature change exceeding a first threshold, detect a transmit antenna change, or determine a quantity of slots since transmitting the request exceeds a second threshold.

[0134] Aspect 18: The apparatus of any of the Aspects 13-17, in which the at leastone processor is further configured to learn the first threshold and the second threshold offline.

[0135] Aspect 19: An apparatus for wireless communication, comprising: at leastone memory; and at least one processor coupled to the at least one memory, the at least one processor configured: to transmit, to a user equipment (UE), permission for uplink transmission of a non-linearity reference signal (NLRS) in response to receiving, from the UE, a request for transmitting the non-linearity reference signal; to receive, from theSeyfarth Ref. No. 72178-006686 32314499932v.1Qualcomm Ref. No.2308905WO UE, the non-linearity reference signal; to estimate a non-linearity distortion model based on receiving the non-linearity reference signal; and to remove a non-linearity effect from a signal received from the UE in a subsequent slot, based on the non-linearity distortion model, to obtain a corrected signal.

[0136] Aspect 20: The apparatus of Aspect 19, in which the non-linearity referencesignal comprises a dedicated pilot signal and the estimating of the non-linearity distortion model occurs separately from estimating a channel between the UE and a network device.

[0137] Aspect 21: The apparatus of Aspect 19, in which the non-linearity referencesignal comprises a sounding reference signal (SRS) having an increased dynamic range, and the at least one processor estimates the non-linearity distortion model iteratively with jointly estimating a channel between the UE and a network device.

[0138] Aspect 22: The apparatus of any of the Aspects 19-21, in which thepermission indicates a type of the non-linearity reference signal, and a slot for transmitting the non-linearity reference signal.

[0139] Aspect 23: The apparatus of any of the Aspects 19-22, in which theprocessor is further configured to determine the non-linearity distortion model should be updated based on at least one of: determining whether a spectrum of the corrected signal is compressed, or determining a current quality of a current slot is a threshold level below a past quality of a past slot.

[0140] Aspect 24: The apparatus of any of the Aspects 19-23, in which the currentquality of the current slot comprises a current error vector magnitude (EVM) of the current slot.

[0141] The foregoing disclosure provides illustration and description, but is notintended to be exhaustive or to limit the aspects to the precise form disclosed. Modifications and variations may be made in light of the above disclosure or may be acquired from practice of the aspects.

[0142] As used, the term “component” is intended to be broadly construed ashardware, firmware, and / or a combination of hardware and software. As used, aSeyfarth Ref. No. 72178-006686 33314499932v.1Qualcomm Ref. No.2308905WO processor is implemented in hardware, firmware, and / or a combination of hardware and software.

[0143] Some aspects are described in connection with thresholds. As used,satisfying a threshold may, depending on the context, refer to a value being greater than the threshold, greater than or equal to the threshold, less than the threshold, less than or equal to the threshold, equal to the threshold, not equal to the threshold, and / or the like.

[0144] It will be apparent that systems and / or methods described may beimplemented in different forms of hardware, firmware, and / or a combination of hardware and software. The actual specialized control hardware or software code used to implement these systems and / or methods is not limiting of the aspects. Thus, the operation and behavior of the systems and / or methods were described without reference to specific software code—it being understood that software and hardware can be designed to implement the systems and / or methods based, at least in part, on the description.

[0145] Even though particular combinations of features are recited in the claimsand / or disclosed in the specification, these combinations are not intended to limit the disclosure of various aspects. In fact, many of these features may be combined in ways not specifically recited in the claims and / or disclosed in the specification. Although each dependent claim listed below may directly depend on only one claim, the disclosure of various aspects includes each dependent claim in combination with every other claim in the claim set. A phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination with multiples of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c- c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c). No element, act, or instruction used should be construed as critical or essential unless explicitly described as such. Also, as used, the articles “a” and “an” are intended to include one or more items, and may be used interchangeably with “one or more.” Furthermore, as used, the terms “set” and “group” are intended to include one or more items (e.g., related items, unrelated items, a combination of related and unrelated items, and / or the like), and may be used interchangeably with “one or more.” Where only oneSeyfarth Ref. No. 72178-006686 34314499932v.1Qualcomm Ref. No.2308905WO item is intended, the phrase “only one” or similar language is used. Also, as used, the terms “has,” “have,” “having,” and / or the like are intended to be open-ended terms. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.Seyfarth Ref. No. 72178-006686 35314499932v.1

Claims

Qualcomm Ref. No.2308905WO CLAIMS WHAT IS CLAIMED IS:

1. A method of wireless communication by a user equipment (UE), comprising: transmitting a request, to a network device, for transmitting a non-linearity reference signal (NLRS), in response to beginning communication with the network in a high power mode or in response to detecting variation of a non-linearity distortion model; receiving, from the network device, permission for uplink transmission of the non-linearity reference signal; and transmitting the non-linearity reference signal to the network device.

2. The method of claim 1, in which the non-linearity reference signal comprises a dedicated pilot signal.

3. The method of claim 1, in which transmitting the non-linearity reference signal comprises increasing a dynamic range of a sounding reference signal (SRS).

4. The method of claim 1, in which the permission indicates a type of the non- linearity reference signal, and a slot for transmitting the non-linearity reference signal.

5. The method of claim 1, in which detecting variation of the non-linearity distortion model comprises at least one of: detecting a UE temperature change exceeding a first threshold, detecting a transmit antenna change, or determining a quantity of slots since transmitting the request exceeds a second threshold.

6. The method of claim 5, further comprising learning the first threshold and the second threshold offline.

7. A method of wireless communication by a network device, comprising: transmitting, to a user equipment (UE), permission for uplink transmission of a non-linearity reference signal (NLRS) in response to receiving, from the UE, a request for transmitting the non-linearity reference signal; receiving, from the UE, the non-linearity reference signal;Seyfarth Ref. No. 72178-006686 36314499932v.1Qualcomm Ref. No.2308905WO estimating a non-linearity distortion model based on receiving the non-linearity reference signal; and removing a non-linearity effect from a signal received from the UE in a subsequent slot, based on the non-linearity distortion model, to obtain a corrected signal.

8. The method of claim 7, in which the non-linearity reference signal comprises a dedicated pilot signal and the estimating of the non-linearity distortion model occurs separately from estimating a channel between the UE and the network device.

9. The method of claim 7, in which the non-linearity reference signal comprises a sounding reference signal (SRS) having an increased dynamic range, and the estimating of the non-linearity distortion model occurs iteratively with jointly estimating a channel between the UE and the network device.

10. The method of claim 7, in which the permission indicates a type of the non- linearity reference signal, and a slot for transmitting the non-linearity reference signal.

11. The method of claim 7, further comprising determining the non-linearity distortion model should be updated based on at least one of: determining whether a spectrum of the corrected signal is compressed, or determining a current quality of a current slot is a threshold level below a past quality of a past slot.

12. The method of claim 11, in which the current quality of the current slot comprises a current error vector magnitude (EVM) of the current slot.

13. An apparatus for wireless communication, comprising: at least one memory; and at least one processor coupled to the at least one memory, the at least one processor configured: to transmit a request, to a network device, for transmitting a non-linearity reference signal (NLRS), in response to beginning communication with the network in a high power mode or in response to detecting variation of a non- linearity distortion model;Seyfarth Ref. No. 72178-006686 37314499932v.1Qualcomm Ref. No.2308905WO to receive, from the network device, permission for uplink transmission of the non-linearity reference signal; and to transmit the non-linearity reference signal to the network device.

14. The apparatus of claim 13, in which the non-linearity reference signal comprises a dedicated pilot signal.

15. The apparatus of claim 13, in which the at least one processor is further configured to increase a dynamic range of a sounding reference signal (SRS).

16. The apparatus of claim 13, in which the permission indicates a type of the non- linearity reference signal, and a slot for transmitting the non-linearity reference signal.

17. The apparatus of claim 13, in which the at least one processor is further configured to detect a UE temperature change exceeding a first threshold, detect a transmit antenna change, or determine a quantity of slots since transmitting the request exceeds a second threshold.

18. The apparatus of claim 17, in which the at least one processor is further configured to learn the first threshold and the second threshold offline.

19. An apparatus for wireless communication, comprising: at least one memory; and at least one processor coupled to the at least one memory, the at least one processor configured: to transmit, to a user equipment (UE), permission for uplink transmission of a non-linearity reference signal (NLRS) in response to receiving, from the UE, a request for transmitting the non-linearity reference signal; to receive, from the UE, the non-linearity reference signal; to estimate a non-linearity distortion model based on receiving the non- linearity reference signal; and to remove a non-linearity effect from a signal received from the UE in a subsequent slot, based on the non-linearity distortion model, to obtain a corrected signal.Seyfarth Ref. No. 72178-006686 38314499932v.1Qualcomm Ref. No.2308905WO 20. The apparatus of claim 19, in which the non-linearity reference signal comprises a dedicated pilot signal and the estimating of the non-linearity distortion model occurs separately from estimating a channel between the UE and a network device.

21. The apparatus of claim 19, in which the non-linearity reference signal comprises a sounding reference signal (SRS) having an increased dynamic range, and the at least one processor estimates the non-linearity distortion model iteratively with jointly estimating a channel between the UE and a network device.

22. The apparatus of claim 19, in which the permission indicates a type of the non- linearity reference signal, and a slot for transmitting the non-linearity reference signal.

23. The apparatus of claim 19, in which the at least one processor is further configured to determine the non-linearity distortion model should be updated based on at least one of: determining whether a spectrum of the corrected signal is compressed, or determining a current quality of a current slot is a threshold level below a past quality of a past slot.

24. The apparatus of claim 23, in which the current quality of the current slot comprises a current error vector magnitude (EVM) of the current slot.Seyfarth Ref. No. 72178-006686 39314499932v.1

Images