DEMODULATION REFERENCE SIGNAL SEQUENCE SIGNALING FOR SINGLE CARRIER WAVEFORMS WITH A NONLINEAR POWER AMPLIFY IN HIGHER BANDS

An apparatus may be configured to transmit (or receive) an indication of a first DMRS, where the first DMRS is identified based on at least two of a non-linearity of a power amplifier of the first device, a modulation and coding scheme (MCS) used for a data transmission associated with the first DMRS, or a channel type of a channel associated with the first DMRS; transmit (or receive), for a second device (or from a first device), the first DMRS for channel estimation at the second device; and transmit (or receive) the data transmission associated with the first DMRS.

TECHNICAL FIELD

The present disclosure relates generally to communication systems, and more particularly, to a demodulation reference signal (DMRS) configuration for an associated data transmission.

INTRODUCTION

BRIEF SUMMARY

In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be configured to transmit an indication of a first DMRS, where the first DMRS is identified based on at least two of a non-linearity of a power amplifier of the first device, a modulation and coding scheme (MCS) used for a data transmission associated with the first DMRS, or a channel type of a channel associated with the first DMRS. The apparatus may also be configured to transmit, for a second device, the first DMRS for channel estimation at the second device.

In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be configured to receive an indication of a first DMRS associated with a first device, where the first DMRS is identified based on at least two of a non-linearity of a power amplifier of the first device, a MCS used for a data transmission associated with the first DMRS, or a channel type of a channel associated with the first DMRS. The apparatus may also be configured to receive, from the first device, the first DMRS for channel estimation. The apparatus may also be configured to receive the data transmission associated with the first DMRS.

DETAILED DESCRIPTION

In some aspects of wireless communications, PA and/or a power amplifier may be used to increase the power of signals (e.g., to improve the quality of transmissions). In some aspects, power amplifiers produce nonlinear distortions due to a saturation property. The power amplifier nonlinear distortion, in some aspects, leads to interference both in the frequency band of transmitted signal (in-band) and in the adjacent frequency bands (out-of-band). The in-band interference caused by nonlinear PA, in some aspects, may degrade the reception performance, while the out-of-band interference may harm the communication systems operating in the adjacent frequency channels. In order not to severely interfere with communication systems operating in the adjacent channels, a transmit spectrum mask may be adopted. To reduce the effects of nonlinear distortion both in-band and out-of-band, a power amplifier should operate in, or close to, a linear region, e.g., the region which is not close to the PA saturation point. In order to operate in, or close to, the linear region the power amplifier may employ a PA backoff (e.g., a reduction in input power to decrease the difference between the ideal (linear) and the actual (saturated) output power). A larger PA backoff, in some aspects, may reduce the transmit power, resulting in reduced PA efficiency and potentially lead to performance degradation for the amplified signal.

Referring again toFIG.1, in certain aspects, the UE104may be configured with a DMRS sequence signaling (DMRS-SS) component198is configured to transmit an indication of a first DMRS and transmit, for a second device, the first DMRS for channel estimation at the second device. The DMRS-SS component198may be configured to receive an indication of a first DMRS associated with a first device; receive, from the first device, the first DMRS for channel estimation; and receive the data transmission associated with the first DMRS. Although the following description may be focused on 5G NR, the concepts described herein may be applicable to other similar areas, such as LTE, LTE-A, CDMA, GSM, and other wireless technologies.

At least one of the TX processor368, the RX processor356, and the controller/processor359may be configured to perform aspects in connection with the DMRS-SS component198ofFIG.1.

In some aspects of wireless communications, PA and/or a power amplifier may be used to increase the power of signals (e.g., to improve the quality of transmissions). In some aspects, power amplifiers produce nonlinear distortions due to a saturation property. The PA nonlinear distortion, in some aspects, leads to interference both in the frequency band of transmitted signal (in-band) (e.g., increasing an error vector magnitude (EVM) at the receiving device) and in the adjacent frequency bands (out-of-band). The in-band interference caused by nonlinear PA, in some aspects, may degrade the reception performance, while the out-of-band interference may harm the communication systems operating in the adjacent frequency channels. In order not to severely interfere with communication systems operating in the adjacent channels, a transmit spectrum mask may be adopted. To reduce the effects of nonlinear distortion both in-band and out-of-band, a power amplifier should operate in, or close to, a linear region, e.g., the region which is not close to the PA saturation point. In order to operate in, or close to, the linear region the power amplifier may employ a PA backoff (e.g., a reduction in input power to decrease the difference between the ideal (linear) and the actual (saturated) output power). A larger PA backoff, in some aspects, may reduce the transmit power, resulting in reduced power amplifier efficiency and potentially lead to performance degradation for the amplified signal.

In some aspects of wireless communication, OFDM-based waveforms may be utilized for higher bands (FR4 and beyond) as they are backward compatible with FR1/FR2/FR2x waveform choice. Additionally, in scenarios where energy efficiency standards and/or thresholds are more relaxed, OFDM-based waveforms offer high spectral efficiency. A single carrier (SC) waveform (e.g., having a lower PAPR compared to a OFDM-based waveform) may be used in some scenarios with high energy efficiency standards and/or thresholds. In some aspects, a lower peak-to-average power ratio (PAPR) may lead to higher PA efficiency and extended battery life. For example, a power amplifier may be more efficient at higher input/output powers associated with a smaller PA backoff that may be used for transmissions with a lower PAPR (e.g., transmissions that experience less negative effects of PA nonlinearity at a same average power as a transmission with a higher PAPR). SC waveforms may also achieve a high data rate due to massive spectrum availability.

In some aspects, to facilitate frequency domain equalization, a CP may be introduced to create OFDM-like blocks or symbols. Guard interval (GI), sometimes referred to as unique word (UW), may be considered as a special case of CP in this context. Both waveforms will probably be included for higher bands. In some aspects, slot-level (or symbol-level) alignment between OFDM and SC waveforms may be desired. Additionally, in some aspects, it may be beneficial to use common numerology to afford a uniform transceiver design (e.g., relating to sampling rates and/or FFT sizes).

In some aspects of wireless communication, e.g., 5G NR, DMRS sequences may be used for channel estimation purposes. The choice of DMRS sequence depends on various factors, e.g., PAPR, good autocorrelation and cross correlation properties, and/or other signal or channel characteristics. For a UL DFT-s-OFDM waveform, in some aspects, a Zadoff-Chu (ZC) sequence may be used in PUCCH and PUSCH across all MCSs (including π/2 BPSK). In some aspects, ZC sequences may be used in PUSCH and PUCCH for MCSs not including π/2 BPSK, where for π/2 BPSK-modulated PUCCH and PUSCH, a π/2 BPSK DMRS is used. In some aspects, the use of the π/2 BPSK DMRS is based on a ZC DMRS having ˜1.6 dB higher PAPR than π/2 BPSK-modulated data. A DMRS sequence having a higher PAPR (e.g., a ZC DMRS) may be affected by the nonlinear PA more severely compared to a data transmission having a lower PAPR (e.g., π/2 BPSK-modulated data). Accordingly, using the example of a ZC DMRS sequence and π/2 BPSK-modulated data, the ZC DMRS sequence experiences a different combined effective wireless channel than π/2 BPSK modulated data. Similar differences in combined effective wireless channel may be experience for other MCSs as well (e.g., for QPSK, 16-QAM, 64-QAM, etc.). A receiving device using the DMRS sequence having a higher PAPR for channel estimation may be systematically inaccurate as to the effect of the PA nonlinearity on the transmission of data having a lower PAPR from the transmitting device (e.g., may overestimate the effect of the PA non-linearity on the lower-PAPR data transmission). The disclosure presents a method and apparatus for determining a suitable (or optimized) DMRS sequence and/or PA backoff based on a number of factors including a MCS used for an associated data transmission, a PA non-linearity at a transmitting device, a numerology, a channel type associated with the DMRS and/or the data transmission, a threshold bit error rate (BER), and/or a threshold block error rate (BLER). The disclosure further presents a method and or apparatus for signaling the determined DMRS. The determined DMRS, in some aspects, may be an optimized DMRS, wherein the optimized DMRS is a DMRS selected from a set of candidate DMRSs as a DMRS best suited for an associated communication or apparatus based on one or more characteristics of the optimized DMRS and the associated communication.

FIG.4is a diagram400illustrating an effect of PA nonlinearity on signals with different PAPRs using a same PA backoff in accordance with different aspects of the disclosure. Diagram400illustrates an output power of a power amplifier based on an input power to the power amplifier. Assuming a same average input power for a first and second transmitted signal (e.g., DMRS sequence or data transmission), a first transmission may have a peak power (Ppeak)401associated with a PAPR402while a second transmission may have a peak power (Ppeak)405associated with a PAPR406. The lower peak power401may be associated with a smaller difference from a linear PA (ΔPpeak)403than a difference from a linear PA (ΔPpeak)407associated with the higher peak power405.

FIG.5is a call flow diagram500illustrating a wireless communication in accordance with some aspects of the disclosure. The wireless communication may be between a first wireless device (e.g., a UE) and second wireless device or between the first wireless device and a network node (e.g., a base station) with either of the participants being the Tx device502or the Rx device504depending on the nature of the wireless communication (e.g., UL vs. DL). A Tx device502may transmit, and a Rx device504may receive, a DMRS configuration506. The DMRS configuration, in some aspects, may include one or more indexed lists of candidate DMRS that may be activated or indicated for use. In some aspects, the DMRS configuration may indicate a mapping between a set of more than two MCSs and a set of more than two DMRSs. Each MCS in the set of more than two MCSs, in some aspects, may be mapped to one DMRS in the set of more than two DMRSs.

In some aspects, the DMRS configuration506may include a plurality of mappings between a set of more than two MCSs and a set of more than two DMRSs. Each mapping in the plurality of mappings, in some aspects, may include a mapping of each MCS in the set of more than two MCSs to one DMRS in the set of more than two DMRSs. In some aspects, the DMRS configuration may be based on a set of characteristics of the Rx device504. The DMRS configuration506, in some aspects, may include a default DMRS to be used in the absence of a contrary indication (e.g., an indication of a different DMRS). The mappings, in some aspects, may map groups of one or more of the characteristics on which the DMRS may be determined to a corresponding DMRS sequence (or set of DMRS parameters). For example, in some aspects, different combinations of an indicated MCS used for an associated data transmission, a PA non-linearity at the Tx device502, a numerology, a channel type associated with the DMRS and/or the data transmission, a threshold BER, and/or a threshold BLER may be mapped to different DMRS sequences. The DMRS configuration506, in some aspects, may be transmitted via RRC signaling.

The Tx device502may transmit, and the Rx device504may receive, a DMRS configuration indication508. The DMRS configuration indication508may include an indication of a particular mapping in the plurality of mappings to use to identify an DMRS. The DMRS configuration indication508m, in some aspects, may be transmitted via a MAC-CE or via control information (e.g., DCI, sidelink control information (SCI), or UCI). In some aspects, the particular mapping may be based on a capability of the Rx device504, such that the DMRS configuration indication508is not transmitted and the Rx device504determines which of the plurality of mappings to use (or activate) based on the capabilities of the Rx device504. Based on one or more of MCS used for an associated data transmission, a PA non-linearity at the Tx device502, a power consumption threshold, a numerology, a channel type associated with the DMRS and/or the data transmission, a threshold BER, and/or a threshold BLER, the Tx device502may determine, at510, an DMRS for transmission from the Tx device502. For example, a DMRS with a PAPR that is closest, or close enough, to a PAPR of the data signal to be transmitted while meeting any other criteria relating to data reliability (BER and/or BLER) and/or power consumption may be determined to be the DMRS. In some aspects, the channel type is one or more of a delay spread dispersive channel, an additive white Gaussian noise channel (AWGN), or an additive signal-dependent Gaussian noise (ASDGN) channel. The non-linearity of the power amplifier, in some aspects, may be associated with a PA backoff magnitude (e.g., may be used, by the Tx device502, to determine a PA backoff magnitude for the Tx device502). For example, in some aspects, the PA backoff magnitude may be based on PAPR of a data transmission, and the DMRS is further identified based on a PAPR of the first DMRS. In some aspects, the MCS of the data transmission may be based on one or more of a suitable data rate associated with the data transmission or a suitable reliability as indicated by a suitable BER or BLER (e.g., a BER or BLER below a threshold BER and/or BLER value).

Based on the determination of the DMRS for transmission from the Tx device, the Tx device502may transmit, and the Rx device504may receive, a DMRS indication512. The DMRS indication512, in some aspects, may be transmitted via one of a MAC-CE or control information (e.g., DCI, UCI, or SCI). In some aspects, the DMRS indication512includes an indication of an MCS associated with the data transmission that, based on a mapping included in DMRS configuration506(e.g., a mapping in a set of mappings indicated by DMRS configuration indication508), may indicate the DMRS to be used by the Tx device502for a subsequent DMRS transmission. In some aspects, the DMRS indication may include an index into an indexed list of possible (or candidate) DMRS included in the DMRS configuration506. The DMRS indication512, in some aspects, may include a sequence indication indicating one of a Zadoff-Chu sequence or a Gold sequence, and/or an MCS, associated with the DMRS determined at510. The MCS associated with the DMRS determined at510, in some aspects, may be one of a same MCS as an associated data transmission, or a different MCS as the associated data transmission. In some aspects, the DMRS indication512may include an indication of a time period for which to use the indicated DMRS sequence (or configuration). The indicated time period may be a particular amount of time or may be a dynamic amount of time based on receiving a subsequent DMRS indication (e.g., the indicated time period may be ‘until another DMRS indication is received’).

Based on the DMRS indication512, the Tx device502may transmit, and Rx device504may receive, a DMRS514. The DMRS514, in some aspects, may be the DMRS indicated in DMRS indication512and the Rx device504may perform a channel estimation at516based on the received DMRS514. The Tx device502may transmit, and the Rx device504may receive, data518associated with DMRS514. The Rx device504may then decode the received data518based on the channel estimation at516.

In some aspects, the Tx device502may transmit, and the Rx device504may receive, a DMRS configuration update520. The DMRS configuration update520may indicate at least one of a change to a correspondence between a particular MCS in the set of more than two MCSs and a particular DMRS in the set of more than two DMRSs or an MCS to add to the set of more than two MCSs and a corresponding DMRS. The DMRS configuration update520, in some aspects, may be transmitted via a MAC-CE.

The Rx device504may, independently, determine an DMRS for the Rx to use for an associated data transmission at522. The Rx device504may then transmit, and Tx device502may receive, DMRS indication524. In some aspects, the DMRS indication524may be based on the DMRS configuration506, the DMRS configuration indication508, or the DMRS configuration update520. The Rx device504may then transmit, and the Tx device502may receive, a DMRS (not shown) as described above in relation to DMRS514that the Tx device502may use to perform a channel estimation (not shown) similar to the channel estimation performed by the Rx device504at516. The Rx device504may also transmit, and the Tx device502may receive, data (not shown) associated with the DMRS (or DMRS indication524) that may be decoded based on the channel estimation.

FIG.6is a diagram600illustrating possible DMRS configurations (e.g., including a first static DMRS configuration mapping602, a second static DMRS configuration mapping604, a candidate static DMRS mappings610, or a fourth dynamic DMRS configuration650) in accordance with some aspects of the disclosure. A first static DMRS configuration mapping602may include (1) a first mapping602aof an indication of a data MCS index equal to 9 to a ZC sequence and (2) a second mapping of an indication of a data MCS index equal to 27 to a QPSK sequence. The first static DMRS configuration, in some aspects, may be transmitted as DMRS configuration506inFIG.5. The first static DMRS configuration mapping602may be transmitted and/or received, in some aspects, via RRC signaling.

At a later time, an update to the first static DMRS configuration mapping602may be received (e.g., corresponding to DMRS configuration update520). The update to the first static DMRS configuration mapping602may be transmitted and/or received via a MAC-CE, in some aspects. The update to the first static DMRS configuration mapping602may include an update to the first mapping602aand the first static DMRS configuration mapping602may be updated to be a second static DMRS configuration mapping604including a second mapping604aof an indication of a data MCS index equal to 9 to a QPSK sequence.

A third set of candidate static DMRS mappings610may include a first candidate DMRS mapping620and a second candidate DMRS mapping630. The first and second candidate DMRS mappings may map sets of transmission characteristics (e.g., an MCS associated with the data transmission, a channel type, a threshold BER, a UE capability, etc.) to a particular DMRS configurations (e.g., a DMRS sequence and/or a MCS associated with the DMRS sequence). For example, the set of transmission characteristics621may be mapped to DMRS configuration623and the set of transmission characteristics625may be mapped to DMRS configuration627in the first candidate DMRS mapping620and the set of transmission characteristics631may be mapped to DMRS configuration633and the set of transmission characteristics635may be mapped to DMRS configuration637in the second candidate DMRS mapping630. The candidate static DMRS mappings610may be received via RRC signaling and a particular candidate DMRS mapping to use may be indicated (e.g., by DMRS configuration indication508ofFIG.5) via one of a MAC-CE or DCI (or UCI and/or SCI). The selected (or indicated) candidate mapping to be used may be UE-specific (e.g., based on UE characteristics and/or capabilities).

Finally, a fourth dynamic DMRS configuration650may include an indexed list of DMRS configurations. In some aspects, one of the DMRS configurations in the indexed list may be designated as a default DMRS configuration. In some aspects, a Tx device may signal a particular DMRS configuration for an upcoming DMRS transmission dynamically via a MAC-CE or DCI (or UCI and/or SCI) including an index into the indexed list.

FIG.7is a flowchart700of a method of wireless communication. The method may be performed by a Tx device for wireless communication such as a wireless device (e.g., the UE104; the Tx device502; the apparatus1104) or a network node (e.g., the base station102; the Tx device502the network entity1202). At706, the Tx device may transmit an indication of a first DMRS. For example,706may be performed by application processor1106, cellular baseband processor1124, transceiver(s)1122, antenna(s)1180, CU processor1212, DU processor1232, RU processor1242, transceiver(s)1246, antenna(s)1280, and/or DMRS-SS component198ofFIGS.11and12. The first DMRS, in some aspects, may be identified based on at least two of a non-linearity of a power amplifier of the first (Tx) device, a MCS used for a data transmission associated with the first DMRS, or a channel type of a channel associated with the first DMRS. The channel type, in some aspects, may be one or more of a delay spread dispersive channel, an AWGN, or an ASDGN channel. In some aspects, the non-linearity of the power amplifier is associated with a PA backoff magnitude based on a PAPR of the data transmission. The first DMRS, in some aspects, may further be identified based on the PAPR of the first DMRS.

In some aspects, the MCS used for the data transmission is based on one or more of a suitable data rate associated with the data transmission or a suitable reliability as indicated by a suitable BER or BLER (e.g., a BER and/or BLER below a threshold BER and/or BLER, respectively). The indication of the first DMRS, in some aspects, may include a sequence indication. The sequence indication, in some aspects, may indicate one of a ZC sequence or a Gold sequence associated with the first DMRS. The indication of the first DMRS, in some aspects, may include an MCS associated with the first DMRS. For example, referring toFIG.5, the Tx device502may transmit, and Rx device504may receive, DMRS indication512.

In some aspects, the indication of the first DMRS transmitted at706may be based on an DMRS configuration indicating at least one mapping between a set of more than two MCSs and a set of more than two DMRSs. In some aspects, the at least one mapping may be one mapping in which each MCS in the set of more than two MCSs is mapped to one DMRS in the set of more than two DMRSs. The at least one mapping, in some aspects, may be a plurality of mappings between a set of more than two MCSs and a set of more than two DMRSs where, for each mapping in the plurality of mappings, each MCS in the set of more than two MCSs is mapped to one DMRS in the set of more than two DMRS.

In some aspects, the DMRS configuration may be based on a set of characteristics of the second device. The set of characteristics may, in some aspects, include a capability (or inability) of the second device to process different types of signals (e.g., types of modulation). The DMRS configuration, in some aspects, includes a default DMRS. For example, referring toFIG.5, the Tx device502may transmit DMRS configuration506.

The indication of the first DMRS transmitted at706, in some aspects, may further be based on an indication of a particular mapping in the plurality of mappings to use to identify an DMRS. In some aspects, the indication of the first DMRS may include an indication of an MCS associated with the data transmission. The particular mapping may be selected based on a set of characteristics of the Tx device or the second (Rx) device. For example, referring toFIG.5, the Tx device502may transmit DMRS configuration indication508.

At708, the Tx device may transmit, for a second device, the first DMRS for channel estimation at the second device. For example,708may be performed by application processor1106, cellular baseband processor1124, transceiver(s)1122, antenna(s)1180, CU processor1212, DU processor1232, RU processor1242, transceiver(s)1246, antenna(s)1280, and/or DMRS-SS component198ofFIGS.11and12. The first DMRS, in some aspects, may be transmitted based on the DMRS indication transmitted at706. For example, referring toFIG.5, the Tx device502, and the Rx device504may receive, DMRS514. The Rx device504may then use the DMRS514to perform a channel estimation at516.

After transmitting the DMRS at708, the Tx device may transmit a data transmission associated with the first DMRS. The data transmission, in some aspects, may use one of a same MCS as the associated first DMRS or a different MCS than the associated first DMRS. For example, referring toFIG.5, the Tx device502may transmit, and the Rx device504may receive, data518.

The Tx device may also transmit, for the second device, an update to the DMRS configuration indicating at least one of a change to a correspondence between a particular MCS in the set of more than two MCSs and a particular DMRS in the set of more than two DMRSs or an MCS to add to the set of more than two MCSs and a corresponding DMRS. In some aspects, the update may apply to a plurality of mappings received at702. For example, referring toFIG.5, the Tx device502may transmit, and the Rx device504may receive, DMRS configuration update520. DMRS configuration update520may include updates to one or more of the mappings included in DMRS configuration506.

In some aspects, the Tx device may receive, from the second device, an indication of a second DMRS for a channel estimation at the Tx device associated with a second data transmission from the second device. In some aspects, the second DMRS is different than the first DMRS based on one or more of the MCS associated with the data transmission from the second device, a waveform associated with the data transmission from the second device, or characteristics of the second device (e.g., a second power amplifier of the second device).

FIG.8is a flowchart800of a method of wireless communication. The method may be performed by a Tx device for wireless communication such as a wireless device (e.g., the UE104; the Tx device502; the apparatus1104) or a network node (e.g., the base station102; the Tx device502the network entity1202). At802, the Tx device may transmit, to a second device, an DMRS configuration indicating at least one mapping between a set of more than two MCSs and a set of more than two DMRSs. For example,802may be performed by application processor1106, cellular baseband processor1124, transceiver(s)1122, antenna(s)1180, CU processor1212, DU processor1232, RU processor1242, transceiver(s)1246, antenna(s)1280, and/or DMRS-SS component198ofFIGS.11and12. In some aspects, the at least one mapping may be one mapping in which each MCS in the set of more than two MCSs is mapped to one DMRS in the set of more than two DMRSs. The at least one mapping, in some aspects, may be a plurality of mappings between a set of more than two MCSs and a set of more than two DMRSs where, for each mapping in the plurality of mappings, each MCS in the set of more than two MCSs is mapped to one DMRS in the set of more than two DMRS.

In some aspects, the DMRS configuration may be based on a set of characteristics of the second device. The set of characteristics may, in some aspects, include a capability (or inability) of the second device to process different types of signals (e.g., types of modulation). The DMRS configuration, in some aspects, includes a default DMRS. For example, referring toFIG.5, the Tx device502may transmit DMRS configuration506.

At804, the Tx device may transmit an indication of a particular mapping in the plurality of mappings to use to identify an DMRS. For example,804may be performed by application processor1106, cellular baseband processor1124, transceiver(s)1122, antenna(s)1180, CU processor1212, DU processor1232, RU processor1242, transceiver(s)1246, antenna(s)1280, and/or DMRS-SS component198ofFIGS.11and12. In some aspects, the indication of the first DMRS may include an indication of an MCS associated with the data transmission. The particular mapping may be selected based on a set of characteristics of the Tx device or the second (Rx) device. For example, referring toFIG.5, the Tx device502may transmit DMRS configuration indication508.

At806, the Tx device may transmit an indication of a first DMRS. For example,806may be performed by application processor1106, cellular baseband processor1124, transceiver(s)1122, antenna(s)1180, CU processor1212, DU processor1232, RU processor1242, transceiver(s)1246, antenna(s)1280, and/or DMRS-SS component198ofFIGS.11and12. The first DMRS, in some aspects, may be identified based on at least two of a non-linearity of a power amplifier of the first (Tx) device, a MCS used for a data transmission associated with the first DMRS, or a channel type of a channel associated with the first DMRS. The channel type, in some aspects, may be one or more of a delay spread dispersive channel, an AWGN, or an ASDGN channel. In some aspects, the non-linearity of the power amplifier is associated with a PA backoff magnitude based on a PAPR of the data transmission. The first DMRS, in some aspects, may further be identified based on the PAPR of the first DMRS.

In some aspects, the MCS used for the data transmission is based on one or more of a suitable data rate associated with the data transmission or a suitable reliability as indicated by a suitable BER or BLER (e.g., a BER and/or BLER below a threshold BER and/or BLER, respectively). The indication of the first DMRS, in some aspects, may include a sequence indication. The sequence indication, in some aspects, may indicate one of a ZC sequence or a Gold sequence associated with the first DMRS. The indication of the first DMRS, in some aspects, may include an MCS associated with the first DMRS. For example, referring toFIG.5, the Tx device502may transmit, and Rx device504may receive, DMRS indication512.

At808, the Tx device may transmit, for a second device, the first DMRS for channel estimation at the second device. For example,808may be performed by application processor1106, cellular baseband processor1124, transceiver(s)1122, antenna(s)1180, CU processor1212, DU processor1232, RU processor1242, transceiver(s)1246, antenna(s)1280, and/or DMRS-SS component198ofFIGS.11and12. The first DMRS, in some aspects, may be transmitted based on the DMRS indication transmitted at806. For example, referring toFIG.5, the Tx device502, and the Rx device504may receive, DMRS514. The Rx device504may then use the DMRS514to perform a channel estimation at516.

After transmitting the DMRS at808, the Tx device may transmit a data transmission associated with the first DMRS at810. For example,810may be performed by application processor1106, cellular baseband processor1124, transceiver(s)1122, antenna(s)1180, CU processor1212, DU processor1232, RU processor1242, transceiver(s)1246, antenna(s)1280, and/or DMRS-SS component198ofFIGS.11and12. The data transmission transmitted at810, in some aspects, may use one of a same MCS as the associated first DMRS or a different MCS than the associated first DMRS. For example, referring toFIG.5, the Tx device502may transmit, and the Rx device504may receive, data518.

At812, the Tx device may transmit, for the second device, an update to the DMRS configuration indicating at least one of a change to a correspondence between a particular MCS in the set of more than two MCSs and a particular DMRS in the set of more than two DMRSs or an MCS to add to the set of more than two MCSs and a corresponding DMRS. For example,812may be performed by application processor1106, cellular baseband processor1124, transceiver(s)1122, antenna(s)1180, CU processor1212, DU processor1232, RU processor1242, transceiver(s)1246, antenna(s)1280, and/or DMRS-SS component198ofFIGS.11and12. In some aspects, the update may apply to a plurality of mappings received at802. For example, referring toFIG.5, the Tx device502may transmit, and the Rx device504may receive, DMRS configuration update520. DMRS configuration update520may include updates to one or more of the mappings included in DMRS configuration506.

Finally, at814, the Tx device may receive, from the second device, an indication of a second DMRS for a channel estimation at the Tx device associated with a second data transmission from the second device. For example,814may be performed by application processor1106, cellular baseband processor1124, transceiver(s)1122, antenna(s)1180, CU processor1212, DU processor1232, RU processor1242, transceiver(s)1246, antenna(s)1280, and/or DMRS-SS component198ofFIGS.11and12. In some aspects, the second DMRS is different than the first DMRS based on one or more of the MCS associated with the data transmission from the second device, a waveform associated with the data transmission from the second device, or characteristics of the second device (e.g., a second power amplifier of the second device). For example, referring toFIG.5, the Rx device504may transmit, and the Tx device502may receive, DMRS indication524.

FIG.9is a flowchart900of a method of wireless communication. The method may be performed by a Rx device for wireless communication such as a wireless device (e.g., the UE104; the Rx device504; the apparatus1104) or a network node (e.g., the base station102; the Rx device504the network entity1202). At906, the Rx device may receive an indication of a first DMRS. For example,906may be performed by application processor1106, cellular baseband processor1124, transceiver(s)1122, antenna(s)1180, CU processor1212, DU processor1232, RU processor1242, transceiver(s)1246, antenna(s)1280, and/or DMRS-SS component198ofFIGS.11and12. The first DMRS, in some aspects, may be identified based on at least two of a non-linearity of a power amplifier of the first (Tx) device, a MCS used for a data transmission associated with the first DMRS, or a channel type of a channel associated with the first DMRS. The channel type, in some aspects, may be one or more of a delay spread dispersive channel, an AWGN, or an ASDGN channel. In some aspects, the non-linearity of the power amplifier is associated with a PA backoff magnitude based on a PAPR of the data transmission. The first DMRS, in some aspects, may further be identified based on the PAPR of the first DMRS.

In some aspects, the MCS used for the data transmission is based on one or more of a suitable data rate associated with the data transmission or a suitable reliability as indicated by a suitable BER or BLER (e.g., a BER and/or BLER below a threshold BER and/or BLER, respectively). The indication of the first DMRS, in some aspects, may include a sequence indication. The sequence indication, in some aspects, may indicate one of a ZC sequence or a Gold sequence associated with the first DMRS. The indication of the first DMRS, in some aspects, may include an MCS associated with the first DMRS. For example, referring toFIG.5, the Rx device504may receive, and Tx device502may transmit, DMRS indication512.

In some aspects, the indication of the first DMRS transmitted at906may be based on an DMRS configuration indicating at least one mapping between a set of more than two MCSs and a set of more than two DMRSs. In some aspects, the at least one mapping may be one mapping in which each MCS in the set of more than two MCSs is mapped to one DMRS in the set of more than two DMRSs. The at least one mapping, in some aspects, may be a plurality of mappings between a set of more than two MCSs and a set of more than two DMRSs where, for each mapping in the plurality of mappings, each MCS in the set of more than two MCSs is mapped to one DMRS in the set of more than two DMRS.

In some aspects, the DMRS configuration may be based on a set of characteristics of the second (Rx) device. The set of characteristics may, in some aspects, include a capability (or inability) of the second (Rx) device to process different types of signals (e.g., types of modulation). The DMRS configuration, in some aspects, includes a default DMRS. For example, referring toFIG.5, the Rx device504may receive DMRS configuration506.

The indication of the first DMRS transmitted at906, in some aspects, may further be based on an indication of a particular mapping in the plurality of mappings to use to identify an DMRS. In some aspects, the indication of the first DMRS may include an indication of an MCS associated with the data transmission. The particular mapping may be selected based on a set of characteristics of the first (Tx) device or the second (Rx) device. For example, referring toFIG.5, the Rx device504may receive DMRS configuration indication508.

At908, the Rx device may receive, from the first (Tx) device, the first DMRS for channel estimation at the second (Rx) device. For example,908may be performed by application processor1106, cellular baseband processor1124, transceiver(s)1122, antenna(s)1180, CU processor1212, DU processor1232, RU processor1242, transceiver(s)1246, antenna(s)1280, and/or DMRS-SS component198ofFIGS.11and12. The first DMRS, in some aspects, may be received based on the DMRS indication received at906. For example, referring toFIG.5, the Rx device504may receive, and the Tx device502may transmit, DMRS514. The Rx device504may then use the DMRS514to perform a channel estimation at516.

After receiving the DMRS at908, the Rx device may receive, at910, a data transmission associated with the first DMRS. For example,910may be performed by application processor1106, cellular baseband processor1124, transceiver(s)1122, antenna(s)1180, CU processor1212, DU processor1232, RU processor1242, transceiver(s)1246, antenna(s)1280, and/or DMRS-SS component198ofFIGS.11and12. The data transmission, in some aspects, may use one of a same MCS as the associated first DMRS or a different MCS than the associated first DMRS. For example, referring toFIG.5, the Rx device504may receive, and the Tx device502may transmit, data518.

The Rx device may also receive, from the first (Tx) device, an update to the DMRS configuration indicating at least one of a change to a correspondence between a particular MCS in the set of more than two MCSs and a particular DMRS in the set of more than two DMRSs or an MCS to add to the set of more than two MCSs and a corresponding DMRS. In some aspects, the update may apply to a plurality of mappings received at902. For example, referring toFIG.5, the Rx device504may receive, and the Tx device502may transmit, DMRS configuration update520. DMRS configuration update520may include updates to one or more of the mappings included in DMRS configuration506.

In some aspects, the Rx device may transmit, to the first (Tx) device, an indication of a second DMRS for a channel estimation at the Rx device associated with a second data transmission from the second (Rx) device. In some aspects, the second DMRS is different than the first DMRS based on one or more of the MCS associated with the data transmission from the second (Rx) device, a waveform associated with the data transmission from the second (Rx) device, or characteristics of the second (Rx) device (e.g., a second power amplifier of the second (Rx) device).

FIG.10is a flowchart1000of a method of wireless communication. The method may be performed by a Rx device for wireless communication such as a wireless device (e.g., the UE104; the Rx device504; the apparatus1104) or a network node (e.g., the base station102; the Rx device504the network entity1202). At1002, the Rx device may receive, from a first (Tx) device, an DMRS configuration indicating at least one mapping between a set of more than two MCSs and a set of more than two DMRSs. For example,1002may be performed by application processor1106, cellular baseband processor1124, transceiver(s)1122, antenna(s)1180, CU processor1212, DU processor1232, RU processor1242, transceiver(s)1246, antenna(s)1280, and/or DMRS-SS component198ofFIGS.11and12. In some aspects, the at least one mapping may be one mapping in which each MCS in the set of more than two MCSs is mapped to one DMRS in the set of more than two DMRSs. The at least one mapping, in some aspects, may be a plurality of mappings between a set of more than two MCSs and a set of more than two DMRSs where, for each mapping in the plurality of mappings, each MCS in the set of more than two MCSs is mapped to one DMRS in the set of more than two DMRS.

In some aspects, the DMRS configuration may be based on a set of characteristics of the second (Rx) device. The set of characteristics may, in some aspects, include a capability (or inability) of the second (Rx) device to process different types of signals (e.g., types of modulation). The DMRS configuration, in some aspects, includes a default DMRS. For example, referring toFIG.5, the Rx device504may receive DMRS configuration506.

At1004, the Rx device may receive an indication of a particular mapping in the plurality of mappings to use to identify an DMRS. For example,1004may be performed by application processor1106, cellular baseband processor1124, transceiver(s)1122, antenna(s)1180, CU processor1212, DU processor1232, RU processor1242, transceiver(s)1246, antenna(s)1280, and/or DMRS-SS component198ofFIGS.11and12. In some aspects, the indication of the first DMRS may include an indication of an MCS associated with the data transmission. The particular mapping may be selected based on a set of characteristics of the Rx device or the second (Rx) device. For example, referring toFIG.5, the Rx device504may receive DMRS configuration indication508.

At1006, the Rx device may receive an indication of a first DMRS. For example,1006may be performed by application processor1106, cellular baseband processor1124, transceiver(s)1122, antenna(s)1180, CU processor1212, DU processor1232, RU processor1242, transceiver(s)1246, antenna(s)1280, and/or DMRS-SS component198ofFIGS.11and12. The first DMRS, in some aspects, may be identified based on at least two of a non-linearity of a power amplifier of the first (Tx) device, a MCS used for a data transmission associated with the first DMRS, or a channel type of a channel associated with the first DMRS. The channel type, in some aspects, may be one or more of a delay spread dispersive channel, an AWGN, or an ASDGN channel. In some aspects, the non-linearity of the power amplifier is associated with a PA backoff magnitude based on a PAPR of the data transmission. The first DMRS, in some aspects, may further be identified based on the PAPR of the first DMRS.

In some aspects, the MCS used for the data transmission is based on one or more of a suitable data rate associated with the data transmission or a suitable reliability as indicated by a suitable BER or BLER (e.g., a BER and/or BLER below a threshold BER and/or BLER, respectively). The indication of the first DMRS, in some aspects, may include a sequence indication. The sequence indication, in some aspects, may indicate one of a ZC sequence or a Gold sequence associated with the first DMRS. The indication of the first DMRS, in some aspects, may include an MCS associated with the first DMRS. For example, referring toFIG.5, the Rx device504may receive, and Tx device502may transmit, DMRS indication512.

At1008, the Rx device may receive, from the first (Tx) device, the first DMRS for channel estimation at the second (Rx) device. For example,1008may be performed by application processor1106, cellular baseband processor1124, transceiver(s)1122, antenna(s)1180, CU processor1212, DU processor1232, RU processor1242, transceiver(s)1246, antenna(s)1280, and/or DMRS-SS component198ofFIGS.11and12. The first DMRS, in some aspects, may be received based on the DMRS indication received at1006. For example, referring toFIG.5, the Rx device504, and the Tx device502may receive, DMRS514. The Tx device502may then use the DMRS514to perform a channel estimation at516.

After receiving the DMRS at1008, the Rx device may receive a data transmission associated with the first DMRS at1010. For example,1010may be performed by application processor1106, cellular baseband processor1124, transceiver(s)1122, antenna(s)1180, CU processor1212, DU processor1232, RU processor1242, transceiver(s)1246, antenna(s)1280, and/or DMRS-SS component198ofFIGS.11and12. The data transmission received at1010, in some aspects, may use one of a same MCS as the associated first DMRS or a different MCS than the associated first DMRS. For example, referring toFIG.5, the Rx device504may receive, and the Tx device502may transmit, data518.

At1012, the Rx device may receive, from the first (Tx) device, an update to the DMRS configuration indicating at least one of a change to a correspondence between a particular MCS in the set of more than two MCSs and a particular DMRS in the set of more than two DMRSs or an MCS to add to the set of more than two MCSs and a corresponding DMRS. For example,1012may be performed by application processor1106, cellular baseband processor1124, transceiver(s)1122, antenna(s)1180, CU processor1212, DU processor1232, RU processor1242, transceiver(s)1246, antenna(s)1280, and/or DMRS-SS component198ofFIGS.11and12. In some aspects, the update may apply to a plurality of mappings received at1002. For example, referring toFIG.5, the Rx device504may receive, and the Tx device502may transmit, DMRS configuration update520. DMRS configuration update520may include updates to one or more of the mappings included in DMRS configuration506.

Finally, at1014, the Rx device may transmit, to the first (Tx) device, an indication of a second DMRS for a channel estimation at the Tx device associated with a second data transmission from the second (Rx) device. For example,1014may be performed by application processor1106, cellular baseband processor1124, transceiver(s)1122, antenna(s)1180, CU processor1212, DU processor1232, RU processor1242, transceiver(s)1246, antenna(s)1280, and/or DMRS-SS component198ofFIGS.11and12. In some aspects, the second DMRS is different than the first DMRS based on one or more of the MCS associated with the data transmission from the second (Rx) device, a waveform associated with the data transmission from the second (Rx) device, or characteristics of the second (Rx) device (e.g., a second power amplifier of the second (Rx) device). For example, referring toFIG.5, the Rx device504may transmit, and the Tx device502may receive, DMRS indication524.

FIG.11is a diagram1100illustrating an example of a hardware implementation for an apparatus1104. The apparatus1104may be a UE, a component of a UE, or may implement UE functionality. In some aspects, the apparatus1104may include a cellular baseband processor1124(also referred to as a modem) coupled to one or more transceivers1122(e.g., cellular RF transceiver). The cellular baseband processor1124may include on-chip memory1124′. In some aspects, the apparatus1104may further include one or more subscriber identity modules (SIM) cards1120and an application processor1106coupled to a secure digital (SD) card1108and a screen1110. The application processor1106may include on-chip memory1106′. In some aspects, the apparatus1104may further include a Bluetooth module1112, a WLAN module1114, an SPS module1116(e.g., GNSS module), one or more sensor modules1118(e.g., barometric pressure sensor/altimeter; motion sensor such as inertial measurement unit (IMU), gyroscope, and/or accelerometer(s); light detection and ranging (LIDAR), radio assisted detection and ranging (RADAR), sound navigation and ranging (SONAR), magnetometer, audio and/or other technologies used for positioning), additional memory modules1126, a power supply1130, and/or a camera1132. The Bluetooth module1112, the WLAN module1114, and the SPS module1116may include an on-chip transceiver (TRX) (or in some cases, just a receiver (RX)). The Bluetooth module1112, the WLAN module1114, and the SPS module1116may include their own dedicated antennas and/or utilize the antennas1180for communication. The cellular baseband processor1124communicates through the transceiver(s)1122via one or more antennas1180with the UE104and/or with an RU associated with a network entity1102. The cellular baseband processor1124and the application processor1106may each include a computer-readable medium/memory1124′,1106′, respectively. The additional memory modules1126may also be considered a computer-readable medium/memory. Each computer-readable medium/memory1124′,1106′,1126may be non-transitory. The cellular baseband processor1124and the application processor1106are each responsible for general processing, including the execution of software stored on the computer-readable medium/memory. The software, when executed by the cellular baseband processor1124/application processor1106, causes the cellular baseband processor1124/application processor1106to perform the various functions described supra. The computer-readable medium/memory may also be used for storing data that is manipulated by the cellular baseband processor1124/application processor1106when executing software. The cellular baseband processor1124/application processor1106may be a component of the UE350and may include the memory360and/or at least one of the TX processor368, the RX processor356, and the controller/processor359. In one configuration, the apparatus1104may be a processor chip (modem and/or application) and include just the cellular baseband processor1124and/or the application processor1106, and in another configuration, the apparatus1104may be the entire UE (e.g., see350ofFIG.3) and include the additional modules of the apparatus1104.

As discussed supra, the DMRS-SS component198is configured to transmit an indication of a first DMRS and transmit, for a second device, the first DMRS for channel estimation at the second device. The DMRS-SS component198may be configured to receive an indication of a first DMRS associated with a first device; receive, from the first device, the first DMRS for channel estimation; and receive the data transmission associated with the first DMRS. The DMRS-SS component198may be within the cellular baseband processor1124, the application processor1106, or both the cellular baseband processor1124and the application processor1106. The DMRS-SS component198may 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 one or more processors, or some combination thereof. As shown, the apparatus1104may include a variety of components configured for various functions. In one configuration, the apparatus1104, and in particular the cellular baseband processor1124and/or the application processor1106, includes means for transmitting an indication of a first DMRS. The apparatus1104, and in particular the cellular baseband processor1124and/or the application processor1106, may also include means for transmitting, for a second device, the first DMRS for channel estimation at the second device. The apparatus1104, and in particular the cellular baseband processor1124and/or the application processor1106, may also include means for transmitting, for the second device, an DMRS configuration indicating a mapping between a set of more than two MCSs and a set of more than two DMRSs, where each MCS in the set of more than two MCSs is mapped to one DMRS in the set of more than two DMRSs, where the indication of the first DMRS includes an indication of the MCS associated with the data transmission. The apparatus1104, and in particular the cellular baseband processor1124and/or the application processor1106, may also include means for transmitting, for the second device, an update to the DMRS configuration indicating at least one of a change to a correspondence between a particular MCS in the set of more than two MCSs and a particular DMRS in the set of more than two DMRSs or an MCS to add to the set of more than two MCSs and a corresponding DMRS. The apparatus1104, and in particular the cellular baseband processor1124and/or the application processor1106, may also include means for transmitting, for the second device, an DMRS configuration indicating a plurality of mappings between a set of more than two MCSs and a set of more than two DMRSs, where, for each mapping in the plurality of mappings, each MCS in the set of more than two MCSs is mapped to one DMRS in the set of more than two DMRSs. The apparatus1104, and in particular the cellular baseband processor1124and/or the application processor1106, may also include means for transmitting an indication of a particular mapping in the plurality of mappings to use to identify an DMRS, where the indication of the first DMRS includes an indication of an MCS associated with the data transmission. The apparatus1104, and in particular the cellular baseband processor1124and/or the application processor1106, may also include means for receiving an indication of a second DMRS associated with a second data transmission from the second device for a channel estimation at the first device. The apparatus1104, and in particular the cellular baseband processor1124and/or the application processor1106, may also include means for receiving an indication of a first DMRS associated with a first device, where the first DMRS is identified based on at least two of a non-linearity of a power amplifier of the first device, a MCS used for a data transmission associated with the first DMRS, or a channel type of a channel associated with the first DMRS. The apparatus1104, and in particular the cellular baseband processor1124and/or the application processor1106, may also include means for receiving, from the first device, the first DMRS for channel estimation. The apparatus1104, and in particular the cellular baseband processor1124and/or the application processor1106, may also include means for receiving the data transmission associated with the first DMRS. The apparatus1104, and in particular the cellular baseband processor1124and/or the application processor1106, may also include means for receiving, from the first device, an DMRS configuration indicating a mapping between a set of more than two MCSs and a set of more than two DMRSs, where each MCS in the set of more than two MCSs is mapped to one DMRS in the set of more than two DMRSs, where the indication of the first DMRS includes an indication of the MCS associated with the data transmission. The apparatus1104, and in particular the cellular baseband processor1124and/or the application processor1106, may also include means for receiving, from the first device, an update to the DMRS configuration indicating at least one of a change to a correspondence between a particular MCS in the set of more than two MCSs and a particular DMRS in the set of more than two DMRSs or an MCS to add to the set of more than two MCSs and a corresponding DMRS. The apparatus1104, and in particular the cellular baseband processor1124and/or the application processor1106, may also include means for receiving, from the first device, an DMRS configuration indicating a plurality of mappings between a set of more than two MCSs and a set of more than two DMRSs, where, for each mapping in the plurality of mappings, each MCS in the set of more than two MCSs is mapped to one DMRS in the set of more than two DMRSs. The apparatus1104, and in particular the cellular baseband processor1124and/or the application processor1106, may also include means for receiving an indication of a particular mapping in the plurality of mappings to use to identify an DMRS, where the indication of the first DMRS includes an indication of the MCS associated with the data transmission. The apparatus1104, and in particular the cellular baseband processor1124and/or the application processor1106, may also include means for transmitting an indication of a second DMRS associated with a second data transmission from the second device for the channel estimation at the first device. The apparatus may include means for performing any of the aspects described in connection with the call flow diagram500ofFIG.5or the flowcharts inFIGS.7-10. The means may be the DMRS-SS component198of the apparatus1104configured to perform the functions recited by the means. As described supra, the apparatus1104may include the TX processor368, the RX processor356, and the controller/processor359. As such, in one configuration, the means may be the TX processor368, the RX processor356, and/or the controller/processor359configured to perform the functions recited by the means.

FIG.12is a diagram1200illustrating an example of a hardware implementation for a network entity1202. The network entity1202may be a BS, a component of a BS, or may implement BS functionality. The network entity1202may include at least one of a CU1210, a DU1230, or an RU1240. For example, depending on the layer functionality handled by the DMRS-SS component198, the network entity1202may include the CU1210; both the CU1210and the DU1230; each of the CU1210, the DU1230, and the RU1240; the DU1230; both the DU1230and the RU1240; or the RU1240. The CU1210may include a CU processor1212. The CU processor1212may include on-chip memory1212′. In some aspects, the CU1210may further include additional memory modules1214and a communications interface1218. The CU1210communicates with the DU1230through a midhaul link, such as an F1 interface. The DU1230may include a DU processor1232. The DU processor1232may include on-chip memory1232′. In some aspects, the DU1230may further include additional memory modules1234and a communications interface1238. The DU1230communicates with the RU1240through a fronthaul link. The RU1240may include an RU processor1242. The RU processor1242may include on-chip memory1242′. In some aspects, the RU1240may further include additional memory modules1244, one or more transceivers1246, antennas1280, and a communications interface1248. The RU1240communicates with the UE104. The on-chip memory1212′,1232′,1242′ and the additional memory modules1214,1234,1244may each be considered a computer-readable medium/memory. Each computer-readable medium/memory may be non-transitory. Each of the processors1212,1232,1242is responsible for general processing, including the execution of software stored on the computer-readable medium/memory. The software, when executed by the corresponding processor(s) causes the processor(s) to perform the various functions described supra. The computer-readable medium/memory may also be used for storing data that is manipulated by the processor(s) when executing software.

As discussed supra, the DMRS-SS component198is configured to transmit an indication of a first DMRS and transmit, for a second device, the first DMRS for channel estimation at the second device. The DMRS-SS component198may be configured to receive an indication of a first DMRS associated with a first device; receive, from the first device, the first DMRS for channel estimation; and receive the data transmission associated with the first DMRS. The DMRS-SS component198may be within one or more processors of one or more of the CU1210, DU1230, and the RU1240. The DMRS-SS component198may 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 one or more processors, or some combination thereof. The network entity1202may include a variety of components configured for various functions. In one configuration, the network entity1202includes means for transmitting an indication of a first DMRS. The network entity1102may also include means for transmitting, for a second device, the first DMRS for channel estimation at the second device. The network entity1102may also include means for transmitting, for the second device, an DMRS configuration indicating a mapping between a set of more than two MCSs and a set of more than two DMRSs, where each MCS in the set of more than two MCSs is mapped to one DMRS in the set of more than two DMRSs, where the indication of the first DMRS includes an indication of the MCS associated with the data transmission. The network entity1102may also include means for transmitting, for the second device, an update to the DMRS configuration indicating at least one of a change to a correspondence between a particular MCS in the set of more than two MCSs and a particular DMRS in the set of more than two DMRSs or an MCS to add to the set of more than two MCSs and a corresponding DMRS. The network entity1102may also include means for transmitting, for the second device, an DMRS configuration indicating a plurality of mappings between a set of more than two MCSs and a set of more than two DMRSs, where, for each mapping in the plurality of mappings, each MCS in the set of more than two MCSs is mapped to one DMRS in the set of more than two DMRSs. The network entity1102may also include means for transmitting an indication of a particular mapping in the plurality of mappings to use to identify an DMRS, where the indication of the first DMRS includes an indication of an MCS associated with the data transmission. The network entity1102may also include means for receiving an indication of a second DMRS associated with a second data transmission from the second device for a channel estimation at the first device. The network entity1102may also include means for receiving an indication of a first DMRS associated with a first device, where the first DMRS is identified based on at least two of a non-linearity of a power amplifier of the first device, a MCS used for a data transmission associated with the first DMRS, or a channel type of a channel associated with the first DMRS. The network entity1102may also include means for receiving, from the first device, the first DMRS for channel estimation. The network entity1102may also include means for receiving the data transmission associated with the first DMRS. The network entity1102may also include means for receiving, from the first device, an DMRS configuration indicating a mapping between a set of more than two MCSs and a set of more than two DMRSs, where each MCS in the set of more than two MCSs is mapped to one DMRS in the set of more than two DMRSs, where the indication of the first DMRS includes an indication of the MCS associated with the data transmission. The network entity1102may also include means for receiving, from the first device, an update to the DMRS configuration indicating at least one of a change to a correspondence between a particular MCS in the set of more than two MCSs and a particular DMRS in the set of more than two DMRSs or an MCS to add to the set of more than two MCSs and a corresponding DMRS. The network entity1102may also include means for receiving, from the first device, an DMRS configuration indicating a plurality of mappings between a set of more than two MCSs and a set of more than two DMRSs, where, for each mapping in the plurality of mappings, each MCS in the set of more than two MCSs is mapped to one DMRS in the set of more than two DMRSs. The network entity1102may also include means for receiving an indication of a particular mapping in the plurality of mappings to use to identify an DMRS, where the indication of the first DMRS includes an indication of the MCS associated with the data transmission. The network entity1102may also include means for transmitting an indication of a second DMRS associated with a second data transmission from the second device for the channel estimation at the first device. The apparatus may include means for performing any of the aspects described in connection with the call flow diagram500ofFIG.5or the flowcharts inFIGS.7-10. The means may be the DMRS-SS component198of the network entity1202configured to perform the functions recited by the means. As described supra, the network entity1202may include the TX processor316, the RX processor370, and the controller/processor375. As such, in one configuration, the means may be the TX processor316, the RX processor370, and/or the controller/processor375configured to perform the functions recited by the means.

In some aspects of wireless communications, PA and/or a power amplifier may be used to increase the power of signals (e.g., to improve the quality of transmissions). In some aspects, power amplifiers produce nonlinear distortions due to a saturation property. The PA nonlinear distortion, in some aspects, leads to interference both in the frequency band of transmitted signal (in-band) (e.g., increasing EVM at the receiving device) and in the adjacent frequency bands (out-of-band). The in-band interference caused by nonlinear PA, in some aspects, may degrade the reception performance, while the out-of-band interference may harm the communication systems operating in the adjacent frequency channels. In order not to severely interfere with communication systems operating in the adjacent channels, a transmit spectrum mask may be adopted. To reduce the effects of nonlinear distortion both in-band and out-of-band, a power amplifier should operate in, or close to, a linear region, e.g., the region which is not close to the PA saturation point. In order to operate in, or close to, the linear region the power amplifier may employ a PA backoff (e.g., a reduction in input power to decrease the difference between the ideal (linear) and the actual (saturated) output power). A larger PA backoff, in some aspects, may reduce the transmit power, resulting in reduced power amplifier efficiency and potentially lead to performance degradation for the amplified signal.

In some aspects of wireless communication, e.g., 5G NR, DMRS sequences may be used for channel estimation purposes. The choice of DMRS sequence depends on various factors, e.g., PAPR, good autocorrelation and cross correlation properties, and/or other signal or channel characteristics. For a UL DFT-s-OFDM waveform, in some aspects, a Zadoff-Chu (ZC) sequence may be used in PUCCH and PUSCH across all MCSs (including π/2 BPSK). In some aspects, ZC sequences may be used in PUSCH and PUCCH for MCSs not including π/2 BPSK, where for π/2 BPSK-modulated PUCCH and PUSCH, a π/2 BPSK DMRS is used. In some aspects, the use of the π/2 BPSK DMRS is based on a ZC DMRS having ˜1.6 dB higher PAPR than π/2 BPSK-modulated data. A DMRS sequence having a higher PAPR (e.g., a ZC DMRS) may be affected by the nonlinear PA more severely compared to a data transmission having a lower PAPR (e.g., π/2 BPSK-modulated data). Accordingly, using the example of a ZC DMRS sequence and π/2 BPSK-modulated data, the ZC DMRS sequence experiences a different combined effective wireless channel than π/2 BPSK modulated data. Similar differences in combined effective wireless channel may be experience for other MCSs as well (e.g., for QPSK, 16-QAM, 64-QAM, etc.).

A receiving device using the DMRS sequence having a higher PAPR for channel estimation may be systematically inaccurate as to the effect of the PA nonlinearity on the transmission of data having a lower PAPR from the transmitting device (e.g., may overestimate the effect of the PA non-linearity on the lower-PAPR data transmission). The disclosure presents a method and apparatus for determining a suitable (or optimized) DMRS sequence and/or PA backoff based on a number of factors including a MCS used for an associated data transmission, a PA non-linearity at a transmitting device, a numerology, a channel type associated with the DMRS and/or the data transmission, a threshold BER, and/or a threshold BLER. The disclosure further presents a method and or apparatus for signaling the determined DMRS

Aspect 1 is a method of wireless communication at a first device, including transmitting an indication of a first DMRS, where the first DMRS is identified based on at least two of a non-linearity of a power amplifier of the first device, a MCS used for a data transmission associated with the first DMRS, or a channel type of a channel associated with the first DMRS; and transmitting, for a second device, the first DMRS for channel estimation at the second device.

Aspect 2 is the method of aspect 1, further including transmitting, for the second device, an DMRS configuration indicating a mapping between a set of more than two MCSs and a set of more than two DMRSs, where each MCS in the set of more than two MCSs is mapped to one DMRS in the set of more than two DMRSs, where the indication of the first DMRS includes an indication of the MCS associated with the data transmission.

Aspect 3 is the method of aspect 2, further including transmitting, for the second device, an update to the DMRS configuration indicating at least one of a change to a correspondence between a particular MCS in the set of more than two MCSs and a particular DMRS in the set of more than two DMRSs or an MCS to add to the set of more than two MCSs and a corresponding DMRS.

Aspect 4 is the method of any of aspects 2 or 3, where the DMRS configuration is based on a set of characteristics of the second device.

Aspect 5 is the method of any of aspects 2 to 4, where the DMRS configuration further includes a default DMRS.

Aspect 6 is the method of aspects 1 to 5, further including transmitting, for the second device, an DMRS configuration indicating a plurality of mappings between a set of more than two MCSs and a set of more than two DMRSs, where, for each mapping in the plurality of mappings, each MCS in the set of more than two MCSs is mapped to one DMRS in the set of more than two DMRSs; and transmitting an indication of a particular mapping in the plurality of mappings to use to identify an DMRS, where the indication of the first DMRS includes an indication of an MCS associated with the data transmission.

Aspect 7 is the method of aspects 1 to 6, where the indication of the first DMRS includes (1) a sequence indication indicating one of a Zadoff-chu sequence or a gold sequence associated with the first DMRS and (2) an MCS associated with the first DMRS.

Aspect 8 is the method of aspects 1 to 7, further including receiving an indication of a second DMRS associated with a second data transmission from the second device for a channel estimation at the first device.

Aspect 9 is the method of aspect 8, where the second DMRS is different than the first DMRS based on one or more of the MCS associated with the data transmission from the second device, a waveform associated with the data transmission from the second device, or characteristics of a second power amplifier of the second device.

Aspect 10 is the method of aspects 1 to 9, where the first DMRS is configured to be used for one of an indicated time or until a time indicated by a transmission of a different DMRS.

Aspect 11 is the method of aspects 1 to 10, where the channel type is one or more of a delay spread dispersive channel, an AWGN channel, or an ASDGN channel.

Aspect 12 is the method of aspects 1 to 11, where the non-linearity of the power amplifier is associated with a PA backoff magnitude.

Aspect 13 is the method of aspects 1 to 12, where the PA backoff magnitude is based on a PAPR of the data transmission, and the first DMRS is further identified based on a PAPR of the first DMRS.

Aspect 14 is the method of aspects 1 to 13, where the MCS used for the data transmission is based on one or more of a suitable data rate associated with the data transmission or a suitable reliability as indicated by a suitable BER or block error rate BLER.

Aspect 15 is a method of wireless communication at a second device, including receiving an indication of a first DMRS associated with a first device, where the first DMRS is identified based on at least two of a non-linearity of a power amplifier of the first device, a MCS used for a data transmission associated with the first DMRS, or a channel type of a channel associated with the first DMRS; receiving, from the first device, the first DMRS for channel estimation; and receiving the data transmission associated with the first DMRS.

Aspect 16 is the method of aspect 15, further including receiving, from the first device, an DMRS configuration indicating a mapping between a set of more than two MCSs and a set of more than two DMRSs, where each MCS in the set of more than two MCSs is mapped to one DMRS in the set of more than two DMRSs, where the indication of the first DMRS includes an indication of the MCS associated with the data transmission.

Aspect 17 is the method of aspect 16, further including receiving, from the first device, an update to the DMRS configuration indicating at least one of a change to a correspondence between a particular MCS in the set of more than two MCSs and a particular DMRS in the set of more than two DMRSs or an MCS to add to the set of more than two MCSs and a corresponding DMRS.

Aspect 18 is the method of any of aspects 16 or 17, where the DMRS configuration is based on a set of characteristics of the second device.

Aspect 19 is the method of any of aspects 16 to 18, where the DMRS configuration further includes a default DMRS.

Aspect 20 is the method of aspects 15 to 19, further including receiving, from the first device, an DMRS configuration indicating a plurality of mappings between a set of more than two MCSs and a set of more than two DMRSs, where, for each mapping in the plurality of mappings, each MCS in the set of more than two MCSs is mapped to one DMRS in the set of more than two DMRSs; and receiving an indication of a particular mapping in the plurality of mappings to use to identify an DMRS, where the indication of the first DMRS includes an indication of the MCS associated with the data transmission.

Aspect 21 is the method of aspects 15 to 20, where the indication of the first DMRS includes (1) a sequence indication indicating one of a Zadoff-chu sequence or a gold sequence associated with the first DMRS and (2) an MCS associated with the first DMRS.

Aspect 22 is the method of aspects 15 to 21, further including transmitting an indication of a second DMRS associated with a second data transmission from the second device for the channel estimation at the first device.

Aspect 23 is the method of aspect 22, where the second DMRS is different than the first DMRS based on one or more of the MCS associated with the data transmission from the second device, a waveform associated with the data transmission from the second device, or characteristics of a second power amplifier of the second device.

Aspect 24 is the method of aspects 1 to 9, where the first DMRS is configured to be used for one of an indicated time or until a time indicated by a transmission of a different DMRS.

Aspect 25 is the method of aspects 15 to 24, where the channel type is one or more of a delay spread dispersive channel, an AWGN channel, or an ASDGN channel.

Aspect 26 is the method of aspects 15 to 25, where the non-linearity of the power amplifier is associated with a PA backoff magnitude.

Aspect 27 is the method of aspects 15 to 26, where the PA backoff magnitude is based on a PAPR of the data transmission, and the first DMRS is further identified based on a PAPR of the first DMRS.

Aspect 28 is the method of aspects 15 to 27, where the MCS used for the data transmission is based on one or more of a suitable data rate associated with the data transmission or a suitable reliability as indicated by a suitable BER or block error rate BLER.

Aspect 29 is an apparatus for wireless communication at a device including a memory and at least one processor coupled to the memory and, based at least in part on information stored in the memory, the at least one processor is configured to implement any of aspects 1 to 28.

Aspect 30 is the apparatus of aspect 29, further including a transceiver or an antenna coupled to the at least one processor.

Aspect 31 is an apparatus for wireless communication at a device including means for implementing any of aspects 1 to 28.