Phase tracking reference signal phase noise tracking

Method and apparatus for PTRS for OTFS waveforms. The apparatus measures a PTRS using an OTFS including a delay-Doppler domain. The OTFS includes a plurality of symbols in the delay-Doppler domain based on the PTRS. A first symbol of the plurality of symbols includes a first PTRS resource sample having a first value in the delay-Doppler domain. A second symbol of the plurality of symbols includes a second PTRS resource sample having a second value in the delay-Doppler domain. The first PTRS resource sample is adjacent to the second PTRS resource sample. The apparatus performs phase noise tracking for a data channel based on the measured PTRS.

TECHNICAL FIELD

The present disclosure relates generally to communication systems, and more particularly, to a configuration for phase tracking reference signal (PTRS) for orthogonal time frequency space (OTFS) waveforms.

INTRODUCTION

BRIEF SUMMARY

Some aspects described herein relate to a network node for wireless communication. The network node may include a memory, and at least one processor communicatively coupled to the memory. The at least one processor may be configured to measure a phase tracking reference signal (PTRS) using an orthogonal time frequency space (OTFS) including a delay-Doppler domain, wherein the OTFS includes a plurality of symbols in the delay-Doppler domain based on the PTRS, wherein a first symbol of the plurality of symbols includes a first PTRS resource sample having a first value in the delay-Doppler domain, wherein a second symbol of the plurality of symbols includes a second PTRS resource sample having a second value in the delay-Doppler domain, and wherein the first PTRS resource sample is adjacent to the second PTRS resource sample. The at least one processor may be configured to perform phase noise tracking for a data channel based on the measured PTRS.

Some aspects described herein relate to a method of wireless communication performed by a network node. The method may include measuring a phase tracking reference signal (PTRS) using an orthogonal time frequency space (OTFS) including a delay-Doppler domain, wherein the OTFS includes a plurality of symbols in the delay-Doppler domain based on the PTRS, wherein a first symbol of the plurality of symbols includes a first PTRS resource sample having a first value in the delay-Doppler domain, wherein a second symbol of the plurality of symbols includes a second PTRS resource sample having a second value in the delay-Doppler domain, and wherein the first PTRS resource sample is adjacent to the second PTRS resource sample. The method may include performing phase noise tracking for a data channel based on the measured PTRS.

Some aspects described herein relate to a non-transitory computer-readable medium having code stored thereon that, when executed by a first network node, causes the first network node to measure a phase tracking reference signal (PTRS) using an orthogonal time frequency space (OTFS) including a delay-Doppler domain, wherein the OTFS includes a plurality of symbols in the delay-Doppler domain based on the PTRS, wherein a first symbol of the plurality of symbols includes a first PTRS resource sample having a first value in the delay-Doppler domain, wherein a second symbol of the plurality of symbols includes a second PTRS resource sample having a second value in the delay-Doppler domain, and wherein the first PTRS resource sample is adjacent to the second PTRS resource sample; and perform phase noise tracking for a data channel based on the measured PTRS.

DETAILED DESCRIPTION

Referring again toFIG.1, in certain aspects, the first network node104may be configured to perform phase noise tracking for a data channel based on measured PTRS. For example, the first network node104may comprise a PTRS component198configured to perform phase noise tracking for a data channel based on measured PTRS. As described herein, a network node, which may be referred to as a node, a network node, a communication node, or a wireless node, may be a base station (e.g., any base station described herein), a UE (e.g., any UE described herein), a network controller, an apparatus, a device, a computing system, one or more components, and/or another suitable processing entity configured to perform any of the techniques described herein. For example, a network node may be a UE. As another example, a network node may be a base station. As another example, a first network node may be configured to communicate with a second network node or a third network node. In one aspect of this example, the first network node may be a UE, the second network node may be a base station, and the third network node may be a UE. In another aspect of this example, the first network node may be a UE, the second network node may be a base station, and the third network node may be a base station. In yet other aspects of this example, the first, second, and third network nodes may be different relative to these examples. Similarly, reference to a UE, base station, apparatus, device, computing system, or the like may include disclosure of the UE, base station, apparatus, device, computing system, or the like being a network node. For example, disclosure that a UE is configured to receive information from a base station also discloses that a first network node is configured to receive information from a second network node. Consistent with this disclosure, once a specific example is broadened in accordance with this disclosure (e.g., a UE is configured to receive information from a base station also discloses that a first network node is configured to receive information from a second network node), the broader example of the narrower example may be interpreted in the reverse, but in a broad open-ended way. In the example above where a UE being configured to receive information from a base station also discloses that a first network node being configured to receive information from a second network node, the first network node may refer to a first UE, a first base station, a first apparatus, a first device, a first computing system, a first one or more components, a first processing entity, or the like configured to receive the information; and the second network node may refer to a second UE, a second base station, a second apparatus, a second device, a second computing system, a first one or more components, a first processing entity, or the like.

The UL transmission is processed at the second network node310(e.g., base station) in a manner similar to that described in connection with the receiver function at the first network node350(e.g., UE). Each receiver318RX receives a signal through its respective antenna320. Each receiver318RX recovers information modulated onto an RF carrier and provides the information to a RX processor370.

In wireless communications, PTRS may allow a receiver of a network node to estimate and compensate phase noise and frequency offsets of a received signal. PTRS may allow for suppression of phase noise and frequency offsets at higher millimeter wave (mmW) frequencies. Transmission of PTRS in an OFDM waveform may be uniformly spaced over time and frequency with the density based on the MCS and the number of RBs transmitted. An OTFS waveform may be configured to support high Doppler channels by transmitting information symbols within a delay-Doppler domain as opposed to a time-frequency domain. OTFS may have some advantages over OFDM, such as but not limited to, constant fading or multi-path diversity. PTRS in OFDM may not be applicable to OTFS due to OTFS transmitting information symbols in the delay-Doppler domain.

Aspects presented herein provide a configuration for PTRS in a delay-Doppler domain to be applicable for an OTFS waveform. For example, a first network node may be configured to perform phase noise tracking for a data channel based on measured PTRS. The first network node may measure a PTRS using an OTFS including a delay-Doppler domain. The OTFS may include a plurality of symbols in the delay-Doppler domain based on the PTRS. A first symbol of the plurality of symbols may include a first PTRS resource sample having a first value in the delay-Doppler domain. A second symbol of the plurality of symbols may include a second PTRS resource sample having a second value in the delay-Doppler domain. The first PTRS resource sample may be adjacent to the second PTRS resource sample. The first network node may perform phase noise tracking for a data channel based on the measured PTRS.

FIG.4is a diagram400of an OTFS modulation scheme. The diagram400includes a time-frequency domain404and the delay-Doppler domain402. The delay-Doppler domain402. The delay-Doppler domain402comprises the precoder406and the decoder414. The precoder406and the decoder414may operate in the delay-Doppler domain. The time-frequency domain404includes the OFDM modulator408, the channel410, and the OFDM demodulator412. Information symbols (e.g., x[k,l]) may be the input to the precoder406which may be in the delay-Doppler domain. Information symbols (e.g., x[k,l]) may be mapped into the time-frequency domain (e.g., X[n,m]) via the precoder406and provided to the OFDM modulator408. Otherwise described, precoder406may process the information symbols in the delay-Doppler domain and output time-frequency domain information (e.g., X[n,m]) based on received input information (e.g., x[k,l]). The precoder406may comprise an 2D inverse symplectic finite Fourier transform (ISFFT). OTFS modulation may, in some examples be interpreted as an ISFFT precoder applied on N consecutive OFDM symbols. The output of the OFDM modulator408(e.g., s(t)) may be transmitter over channel410(e.g., H(t,f)) to produce the signal r(t). The signal r(t) is demodulated using OFDM demodulator412to obtain the information symbols (e.g., Y[n,m]). The information symbols (e.g., Y[n,m]) may be in the time-frequency domain and are inputted into the decoder414, where the decoder414processes the time-frequency domain information symbols (e.g., Y[n,m]) and are mapped back to the delay-Doppler domain via the decoder414to obtain the delay-Doppler domain symbols (e.g., y[k,l]). The decoder414may comprise a symplectic finite Fourier transform (SFFT).

The information symbols (e.g., x[k,l]) may be treated as points on a 2D delay-Doppler grid. The information symbols may be mapped in the delay-Doppler domain to time-frequency domain through the ISFFT operation, represented by the equation:

X[n,m]=1N⁢M⁢∑k=0N-1∑l=0M-1×[k,l]⁢ej⁢2⁢π⁡(n⁢kN-m⁢lM)
where N is the number of OFDM symbols, M is the number of subcarriers.

Due to ISFFT, each information symbol may occupy the entire time and bandwidth. Information symbols may be placed in the delay-Doppler domain rather than in the time-frequency domain in OFDM.

FIG.5is a diagram500of an example transmitter using OTFS and the delay-Doppler domain. The OTFS waveform502may comprise an M×N matrix, where M is the delay, and N is the Doppler. The OTFS waveform502may comprise The OTFS waveform502may be comprised of MN*log2(Q) bits. The OTFS waveform502comprising the delay-Doppler information symbols may be converted to the time-frequency domain using ISFFT504. The ISFFT504may comprise a plurality of IFFTs510that receive the waveform502and converts that N Doppler symbols into N time symbols. The waveform is then input into a plurality of FFTs512that produce the converted time-frequency domain information symbols506, where the frequency includes M subcarriers. The symbols at the output of the ISFFT504represent the time-frequency domain, which may be similar as an OFDM waveform. The time-frequency domain information symbols506may be input into a plurality of IFFTs514to obtain the time-domain signal508. The time-domain signal508may be comprised of N symbols, with each symbol having M samples.

FIG.6Ais a diagram600illustrating an example of OTFS in accordance with the techniques described herein. For example, the diagram600provides an example of an ISFFT size. The OTFS waveform602, which may be similar to OTFS waveform502, may be provided to the plurality of IFFTs606of the precoder604to perform an inverse ZAC transform, which converts the2D waveform602to a 1D waveform.

FIG.6Bis a diagram610illustrating an example of OTFS in accordance with the techniques described herein. For example, the diagram610provides an example of an FFT size. The 1D waveform608ofFIG.6A, may be transmitted over a time varying channel612. The received channel may be demodulated via demodulator614to perform a ZAC transform, which converts the 1D waveform back to a 2D waveform. The received channel may be provided to the plurality of FFTs616to perform the ZAC transform, which results in the delay-Doppler domain information symbols.

FIG.7is a diagram700of example OTFS channel estimation. For example, a network node may use OTFS to estimate the delay-Doppler channel rather than the time-frequency channel by placing pilot symbols in the delay-Doppler domain. Each pilot symbol may occupy the entire time-frequency plane, due to the ISFFT transform. The delay-Doppler channel704may be related to the time-frequency channel702through ISFFT transform and its estimation may have several advantages over the time-frequency channel702. For example, the delay-Doppler channel704may be sparse. In addition, the delay-Doppler channel704may occupy a smaller portion of the grid, in comparison to the time-frequency channel702. The maximum delay and Doppler spreads of the delay-Doppler channel704may be much smaller than the symbol duration and sub-carrier spacing of the time-frequency channel702. In some instances, the delay-Doppler channel704may be less than 20%, for example, in each dimension.

FIGS.8A-8Care diagrams800,810,820, respectively, of example OTFS input-output relations. Diagram800ofFIG.8Aprovides an example of an input signal (e.g., x[k,l]). Diagram810ofFIG.8Bprovides an example of a channel (e.g., h[k,l]). Diagram820ofFIG.8Cprovides an example of an output signal (e.g., y[k,l]). The OTFS input-output relations in the case of the delay-Doppler channel may comprise a 2D circular convolution with varying phase shifts, which may be expressed by the following equation:

αi(k,l)={1lτi≤l<Me-j⁢2⁢π⁡([k-kvl]NN)0≤l<lτl.,
P is the number of delay-Doppler paths, lτ and kvare the delay and Doppler taps, respectively.

Due to the under-spread nature, the channel804may occupy a small fraction (e.g., around the origin) of the delay-Doppler grid.

FIG.9illustrates an example of one or more techniques described herein, such as use of the delay-Doppler domain to measure PTRS. Phase noise may change as a function of time. Tracking the phase noise may require more frequent pilots (e.g., PTRS resource samples) in the time domain, and less frequent pilots (e.g., PTRS resource samples) in the frequency domain. In some aspects, a network node described herein may be configured to receive a PTRS in the time domain. The PTRS may include a plurality of symbols. Each symbol of the PTRS may include one or more PTRS resource samples. The network node may be configured to convert the one or more PTRS resource samples into the delay-Doppler domain, such that the one or more PTRS resource samples are in the OTFS. In some aspects, the network node may be configured to modify one or more values corresponding to the one or more PTRS resource samples in the delay-Doppler domain. The network node may be configured transform a received PTRS into the delay-Doppler domain. In some aspects, the network node may be configured to transform a PTRS into the delay-Doppler domain by using a ZAC transform. As used herein, reference to a ZAC transform includes reference to the ZAC transform or any transform used convert information (e.g., samples) from the delay-Doppler domain information to the time domain, or vice-versa. Due to, for example, the ZAC transform, PTRS resource samples may be uniformly spread or spaced apart from other PTRS resource samples, which may enable phase noise tracking. In some aspects, a plurality of PTRS resource samples having a same, constant (e.g., zero values), or sequenced value in the delay-Doppler domain may result in the PTRS resource samples repeating in the time domain. PTRS resource sample density in the delay-Doppler domain may determine the PTRS density within a symbol and may be based on one or more factors, such as the phase noise and the MCS. The network node may be configured to apply an inverse ZAC transform on the PTRS resource samples in the delay-Dopper domain to convert or otherwise transform such PTRS resource samples into the time domain.

In the aspect shown,FIG.9illustrates a grid910having a Doppler axis and a Delay axis. Each cell in grid910represents a type of sample. WhileFIG.9shows two types of samples (a first type of samples being PTRS resource samples and a second type of samples being data samples), other aspects may include one or more additional types of samples (e.g., DMRS samples or any other type of sample). The z-axis may be viewed as extending perpendicularly away from the figure. For example, a PTRS resource sample value of a first value extends in the z-direction, and a PTRS resource sample value of a second value more than the first value extends in the z-direction by more than the first value. In this way, the two-dimensional grid910shows magnitude from a top view perspective due to the two-dimensional nature of the grid910. The magnitude of each respective PTRS resource sample may be represented by a complex number (e.g., a +bj, where “a” represents the real component and “b” represents the imaginary component).

The aspect shown inFIG.9illustrates a plurality of symbols902in the delay-Doppler domain. The plurality of symbols902are represented by902-1,902-2,902-3,902-4,902-5, and902-n, where902-n represents the nth symbol. In some aspects, the plurality of symbols902may include two or more symbols even though the aspect shown inFIG.9shows5symbols and an nth symbol. For example, n may equal two or more in such aspects. Each respective symbol of the plurality of symbols902may include one or more PTRS resource samples. Each PTRS resource sample may have a corresponding value.

Each respective symbol of the plurality of symbols902may include one or more PTRS resource samples. In the aspect ofFIG.9, each respective symbol includes its own respective data samples908. Similarly, each respective symbol includes one or more respective PTRS resource samples904. For example, symbol902-1includes one or more PTRS resource samples904-1A (representing a first PTRS resource sample of symbol902-1),904-2A (representing a second PTRS resource sample of symbol902-1), and904-nA (representing an nth PTRS resource sample of symbol902-1). Similarly, symbol902-2includes one or more PTRS resource samples904-1B (representing a first PTRS resource sample of symbol902-2),904-2B (representing a second PTRS resource sample of symbol902-2), and904-nB (representing an nth PTRS resource sample of symbol902-2). Similarly, symbol902-n includes one or more PTRS resource samples904-1F (representing a first PTRS resource sample of symbol902-n),904-2F (representing a second PTRS resource sample of symbol902-n), and904-nF (representing an nth PTRS resource sample of symbol902-n).

In the aspect shown inFIG.9, PTRS resource samples in a respective symbol of the plurality of symbols902are not adjacent to each other because there is at least one respective non-PTRS resource sample (e.g., data sample908) separating them along the delay axis. PTRS resource samples904-1A,904-2A, and904-nA in symbol902-1are not adjacent to each other because there is at least one respective data sample908(shown as 7 data samples in the illustrated aspect) separating them along the delay axis. Similarly, PTRS resource samples904-1B,904-2B, and904-nB in symbol902-2are not adjacent to each other because there is at least one respective data sample908separating them along the delay axis. Similarly, PTRS resource samples904-1F,904-2F, and904-nF in symbol902-n are not adjacent to each other because there is at least one respective data sample908separating them along the delay axis. In some aspects, m data samples may separate PTRS resource samples in each symbol. In the aspect ofFIG.9, m is shown as equaling 7 (i.e., there are 7 data samples between the PTRS resource samples in each respective symbol of the plurality of symbols902). However, in other aspects, m may be an integer greater than or less than 7, such as 1, 2, 3, 4, 5, 6, 8, 9, 10, 11, 12, 13, 14, 15, or greater.

In the aspect shown inFIG.9, one or more PTRS resource samples of one symbol may be adjacent along the Doppler axis to one or more PTRS resource samples of one or more other symbols. For example, PTRS resource sample904-1A is adjacent to PTRS resource sample904-1B, PTRS resource sample904-2A is adjacent to PTRS resource sample904-2B, and PTRS resource sample904-nA is adjacent to PTRS resource sample904-nB. Similarly, PTRS resource sample904-1D is adjacent to PTRS resource sample904-1C and PTRS resource sample904-1E, PTRS resource sample904-2D is adjacent to PTRS resource sample904-2C and PTRS resource sample904-2E, and PTRS resource sample904-nD is adjacent to PTRS resource sample904-nC and PTRS resource sample904-nE.

The network node may be configured to not modify the values of PTRS resource samples in the delay-Doppler domain corresponding to at least one symbol, and may be configured to modify the values of the one or more PTRS resource samples in the delay-Doppler domain corresponding to at least one symbol to be another value, such as zero. An unmodified value corresponding to a PTRS resource sample may be non-zero. A modified value corresponding to a PTRS resource sample may be zero or non-zero.

In the aspect shown inFIG.9, the first symbol902-1is shown with unmodified or modified PTRS resource values, and the second symbol902-2through the nth symbol902-n are shown as having modified PTRS resource values. In some aspects, the modified PTRS resource sample values may be zero. In other aspects, the modified PTRS resource sample values may be based on a sequence. In other aspects, the modified and the unmodified PTRS resource sample values may be based on a sequence, such as Zadoff Chu (ZC) sequence or a pseudo-random noise (PN) sequence. In some aspects, the PTRS resource sample values for the first symbol902-1may be non-zero, and the PTRS resource sample values for any other symbol may be zero.

The plurality of symbols902and the respective PTRS resource samples904corresponding thereto have been converted or transformed into the delay-Doppler domain. The plurality of symbols902and the respective PTRS resource samples904corresponding thereto are respectively converted or transformed into the plurality of symbols902′ and the respective PTRS resource samples904′ corresponding thereto in the time domain. For example, the network node may be configured to apply an inverse ZAC transform on the plurality of symbols902shown in grid910to transform them into the plurality of symbols902′ in the time domain, which is shown in the aspect ofFIG.9. For example, symbol902-1in the delay-Doppler domain corresponds to symbol902-1′ in the time domain. Similarly, PTRS resource samples904-1A,904-2A, and904-nA in the delay-Doppler domain respectively correspond to PTRS resource samples904-1A′,904-2A′, and904-nA′ in the time domain. As another example, symbol902-n in the delay-Doppler domain corresponds to symbol902-n′ in the time domain. Similarly, PTRS resource samples904-1F,904-2F, and904-nF in the delay-Doppler domain respectively correspond to PTRS resource samples904-1F′,904-2F′, and904-nF′ in the time domain.

FIGS.10A and10Billustrate an example of one or more techniques described herein, such as use of the delay-Doppler domain to measure PTRS. The aspects shown inFIGS.10A and10Bare similar to the aspects shown inFIG.9, except thatFIGS.10A and10Bshow an example of PTRS resource sample groups where each respective group includes a plurality of respective PTRS resource samples. For example, each respective group of PTRS resource samples may include two or more adjacent PTRS resource samples.FIGS.10A and10Billustrate an example where each group includes three adjacent PTRS resource samples along the delay axis. In other aspects, each group may include less than three adjacent PTRS resource samples. In other aspects, each group may include more than three adjacent PTRS resource samples.

In the aspect shown,FIG.10Aillustrates a grid1010having a Doppler axis and a Delay axis. Each cell in grid1010represents a type of sample. WhileFIG.10Ashows two types of samples (a first type of samples being PTRS resource samples and a second type of samples being data samples), other aspects may include one or more additional types of samples (e.g., DMRS samples or any other type of sample). The z-axis may be viewed as extending perpendicularly away from the figure. For example, a PTRS resource sample value of a first value extends in the z-direction, and a PTRS resource sample value of a second value more than the first value extends in the z-direction by more than the first value. In this way, the two-dimensional grid1010shows magnitude from a top view perspective due to the two-dimensional nature of the grid1010. The magnitude of each respective PTRS resource sample may be represented by a complex number (e.g., a+bj, where “a” represents the real component and “b” represents the imaginary component).

The aspect shown inFIG.10Aillustrates a plurality of symbols1002in the delay-Doppler domain. The plurality of symbols1002are represented by1002-1,1002-2,1002-3,1002-4,1002-5, and1002-n, where1002-n represents the nth symbol. In some aspects, the plurality of symbols1002may include two or more symbols even though the aspect shown inFIG.10Ashows 5 symbols and an nth symbol. For example, n may equal two or more in such aspects. Each respective symbol of the plurality of symbols1002may include one or more PTRS resource samples. Each PTRS resource sample may have a corresponding value.

In the aspect shown inFIG.10A, the respective groups of PTRS resource samples of each respective symbol are separated by at least one non-PTRS resource sample (e.g., data sample1008). For example, the first group G1of PTRS resource samples in symbol1002-1and the second group G2of PTRS resource samples in symbol1002-1are separated by 5 data samples. In some aspects, m data samples may separate different groups of PTRS resource samples in each symbol. In the aspect ofFIG.10A, m is shown as equaling 5 (i.e., there are 5 data samples between the PTRS resource samples in each respective symbol of the plurality of symbols1002). However, in other aspects, m may be an integer greater than or less than 5, such as 1, 2, 3, 4, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or greater.

In the aspect shown inFIG.10A, one or more groups of PTRS resource samples of one symbol may be adjacent along the Doppler axis to one or more groups of PTRS resource samples of one or more other symbols. For example, the first group G1of PTRS resource samples in symbol1002-1is adjacent to the first group G1of PTRS resource samples in symbol1002-2. Similarly, the second group G2of PTRS resource samples in symbol1002-2is adjacent to the second group G2of PTRS resource samples in symbol1002-1and the second group G2of PTRS resource samples in symbol1002-3.

The network node may be configured to not modify the values of PTRS resource samples in the delay-Doppler domain corresponding to at least one symbol, and may be configured to modify the values of the one or more PTRS resource samples in the delay-Doppler domain corresponding to at least one symbol to be another value, such as zero. An unmodified value corresponding to a PTRS resource sample may be non-zero. A modified value corresponding to a PTRS resource sample may be zero or non-zero.

In the aspect shown inFIG.10A, the first symbol1002-1is shown with unmodified or modified PTRS resource values, and the second symbol1002-2through the nth symbol1002-n are shown as having modified PTRS resource values. In some aspects, the modified PTRS resource sample values may be zero. In other aspects, the modified PTRS resource sample values may be based on a sequence. In other aspects, the modified and the unmodified PTRS resource sample values may be based on a sequence, such as Zadoff Chu (ZC) sequence or a pseudo-random noise (PN) sequence. In some aspects, the PTRS resource sample values for the first symbol1002-1may be non-zero, and the PTRS resource sample values for any other symbol may be zero.

The plurality of symbols1002and the respective PTRS resource samples1004corresponding thereto are respectively converted or transformed into the plurality of symbols1002′ and the respective PTRS resource samples1004′ corresponding thereto in the time domain. For example, the network node may be configured to apply an inverse ZAC transform on the plurality of symbols1002shown in grid1010inFIG.10Ato transform them into the plurality of symbols1002′ in the time domain shown inFIG.10B. For example, symbol1002-1in the delay-Doppler domain corresponds to symbol1002-1′ in the time domain. Similarly, the first group G1of PTRS resource samples of symbol1002-1in the delay-Doppler domain respectively corresponds to the first group G1′ of PTRS resource samples of symbol1002-1′ in the time domain. As another example, the nth group Gn of PTRS resource samples of symbol1002-n in the delay-Doppler domain respectively corresponds to the nth group Gn' of PTRS resource samples of symbol1002-n′ in the time domain.

FIGS.11A and11Billustrate an example of a PTRS in relation to a DMRS in a different aspect ofFIG.9. As shown inFIG.11A, one or symbols902may include one or more DMRS samples. For example, symbol902-1includes four adjacent DMRS samples, symbol902-2includes four adjacent DMRS samples, symbol902-3includes four adjacent DMRS samples, and symbol902-4includes four adjacent DMRS samples. In some aspects, the DMRS may be spaced a first number of samples (e.g., data samples) from a PTRS resource sample, and PTRS resource samples may be spaced a second number of samples (e.g., data samples) from other PTRS resource samples. In some aspects, the first number of samples may be equal to the second number of samples to increase performance. In other aspects, the first number of samples may be unequal to the second number of samples. In the aspect shown inFIG.11A, the first number of samples and the second number of samples equal 3 samples. In other aspects, the first number of samples and the second number of samples may be less than 3 or greater than 3. In some aspects, the DMRS may be placed in the delay-Doppler domain with a delay width approximately 2 times the maximum delay spread and Doppler width approximately 2 times the Doppler spread. The OTFS channel estimation may include the phase noise component at such time instances, due to the DMRS structure.

For phase noise estimation, after the channel estimation and equalization in the delay-Doppler domain, an IFFT having a dimension equal to the Doppler for each of the estimated sample vectors at the PTRS positions in the delay-Doppler domain may be applied. The IFFT may transform the PTRS samples to the time domain. With the PTRS samples in the time domain, the phase noise may be estimated based on the PTRS samples. In some aspects, such as for grouped PTRS samples, the phase noise may be estimated from the average over the PTRS samples. Phase noise for other time samples may be estimated by interpolating over PTRS samples in the time domain.

For phase noise compensation, after the channel equalization, the estimated data samples in the delay-Doppler domain may be converted to the time domain. The application of the phase noise compensation may be performed in the time domain, followed by converting the time domain samples back to the delay-Doppler domain.

In some aspects, the density of the PTRS in the delay-Doppler domain may be selected based on at least one of the MCS, the number of RBs, or phase noise. In some aspects, the density of the PTRS may be selected by a base station. In some aspects, a UE may be configured to indicate to the base station the highest density of PTRS that the UE may be able to process. The base station may transmit the density of PTRS either explicitly or implicitly based on the MCS and the number of transmitted RB s through DCI.

FIG.12is a call flow diagram1200of signaling between a first network node1202and a second network node1204. In some aspects, the first network node1202or the second network node may comprise a UE or a base station. In some aspects, the second network node1204(e.g., base station) may be configured to provide at least one cell. In some aspects, the first network node1202(e.g., UE) may be configured to communicate with the second network node1204(e.g., base station). For example, in the context ofFIG.1, the second network node1204(e.g., base station) may correspond to base station102/180and, accordingly, the cell may include a geographic coverage area110in which communication coverage is provided and/or small cell102′ having a coverage area110′. Further, a first network node1202(e.g., UE) may correspond to at least UE104. In another example, in the context of FIG.3, the second network node1204(e.g., base station) may correspond to base station310and the first network node1202(e.g., UE) may correspond to UE350.

As illustrated at1206, the first network node1202may transmit information indicating a highest density PTRS that the first network node may process to the second network node1204. The second network node1204may receive the information indicating the highest density PTRS that the first network node may process from the first network node1202. The PTRS included in the OTFS may be based on the information transmitted. In some aspects, the second network node may comprise a UE, a base station, an apparatus, a device, or a computing system configured to perform any techniques described herein. In some aspects, the information may be transmitted in uplink control information (UCI).

As illustrated at1208, the second network node1204may transmit information indicating a density of the PTRS to the first network node1202. The first network node1202may receive the information indicating the density of the PTRS from the second network node1204. The PTRS may be measured based on the information received from the second network node. In some aspects, the information is received in downlink control information (DCI).

As illustrated at1210, the second network node1204may transmit the PTRS to the first network node1202. The first network node1202may receive the PTRS from the second network node1204.

As illustrated at1212, the first network node1202may convert the PTRS. The first network node may convert the PTRS into the delay-Doppler domain of the OTFS.

As illustrated at1214, the first network node1202may measure a PTRS using an OTFS including a delay-Doppler domain, for example as disclosed inFIGS.9-11. The OTFS may include a plurality of symbols in the delay-Doppler domain based on the PTRS. A first symbol of the plurality of symbols may include a first PTRS resource sample having a first value in the delay-Doppler domain. A second symbol of the plurality of symbols may include a second PTRS resource sample having a second value in the delay-Doppler domain. The first PTRS resource sample may be adjacent to the second PTRS resource sample.

The first value or the second value may comprise a complex number comprising a real component and an imaginary component. In some instances, the imaginary component may have a value of zero (0), while the real component may have a value greater than zero (0). In some instances, at least one of the imaginary component or the real component may have a non-zero value. In some aspects, the first value and the second value may be based on a sequence. The sequence may include a Zadoff Chu (ZC) sequence or a pseudo-random noise (PN) sequence. In some aspects, the first value of the first PTRS resource sample may be non-zero and the second value of the second PTRS resource sample may be zero.

The first symbol may include a first plurality of PTRS resource samples in the delay-Doppler domain. Each respective PTRS resource sample of the first plurality of PTRS resource samples may have a respective value. In some aspects, the first plurality of PTRS resource samples may include the first PTRS resource sample. In some aspects, the second symbol may include a second plurality of PTRS resource samples in the delay-Doppler domain. Each respective PTRS resource sample of the second plurality of PTRS resource samples may have a respective value. The second plurality of PTRS resource samples may include the second PTRS resource sample. In some aspects, the respective value may be non-zero for each respective PTRS resource sample in the first plurality of PTRS resource samples. For example, the first and second values may be non-zero and zero, respectively. In some aspects, the respective value may be zero for each respective PTRS resource sample in the second plurality of PTRS resource samples. In some aspects, the respective value for each respective PTRS resource sample in the first plurality of PTRS resource samples may be based on a sequence. In some aspects, the respective value for each respective PTRS resource sample in the second plurality of PTRS resource samples may be based on the sequence.

The first symbol may include a first plurality of PTRS resource samples in the delay-Doppler domain. Each respective PTRS resource sample of the first plurality of PTRS resource samples may have a respective value. In some aspects, the first plurality of PTRS resource samples may include the first PTRS resource sample. Each respective symbol of the plurality of symbols that is different from the first symbol may include a respective plurality of PTRS resource samples in the delay-Doppler domain. Each respective PTRS resource sample of each respective symbol that is different from the first symbol may have a respective value. In some aspects, the respective value may be non-zero for each respective PTRS resource sample in the first plurality of PTRS resource samples. In some aspects, the respective value may be zero for each respective PTRS resource sample of each respective symbol that is different from the first symbol. In some aspects, the respective value for each respective PTRS resource sample in the first plurality of PTRS resource samples may be based on a sequence. In some aspects, the respective value for each respective PTRS resource sample of each respective symbol that is different from the first symbol may be based on the sequence.

The first symbol may include a first plurality of PTRS resource samples spaced apart along a delay axis in the delay-Doppler domain. In some aspects, the first plurality of PTRS resource samples may include the first PTRS resource sample. In some aspects, the second symbol may include a second plurality of PTRS resource samples spaced apart along the delay axis in the delay-Doppler domain. The second plurality of PTRS resource samples may include the second PTRS resource sample. In some aspects, the PTRS resource samples of the first plurality of PTRS resource samples may be spaced apart along the delay axis in the delay-Doppler domain by n delay-Doppler domain samples, where n may be an integer greater than zero. In some aspects, the PTRS resource samples of the second plurality of PTRS resource samples may be spaced apart along the delay axis in the delay-Doppler domain by n delay-Doppler domain samples, where n may be an integer greater than zero. In some aspects, the n delay-Doppler domain samples may be data samples in the delay-Doppler domain.

The first symbol may include a first plurality of PTRS resource samples that are adjacent along a delay axis in the delay-Doppler domain and a second plurality of PTRS resource samples that are adjacent along the delay axis in the delay-Doppler domain. The first plurality and second plurality of PTRS resource samples of the first symbol may be spaced apart along the delay axis in the delay-Doppler domain by n delay-Doppler domain samples. The second symbol may include a first plurality of PTRS resource samples that are adjacent along the delay axis in the delay-Doppler domain and a second plurality of PTRS resource samples that are adjacent along the delay axis in the delay-Doppler domain. The first plurality and second plurality of PTRS resource samples of the second symbol may be spaced apart along the delay axis in the delay-Doppler domain by n delay-Doppler domain samples, where n is an integer greater than zero. In some aspects, one of the first plurality or the second plurality of PTRS resource samples of the first symbol may include the first PTRS resource sample. In some aspects, one of the first plurality or the second plurality of PTRS resource samples of the second symbol may include the second PTRS resource sample. In some aspects, the first plurality and second plurality of PTRS resource samples of the first symbol may each include m adjacent PTRS resource samples, where m is an integer greater than zero. In some aspects, the first plurality and second plurality of PTRS resource samples of the second symbol may each includes m adjacent PTRS resource samples, where m is an integer greater than zero.

The first symbol may include a first plurality of demodulation reference signal (DMRS) samples. The second symbol may include a second plurality of DMRS samples. In some aspects, the first plurality of DMRS samples may be adjacent to the second plurality of DMRS samples in the delay-Doppler domain.

The first PTRS resource sample may be comprised within a first set of PTRS resource samples and the second PTRS resource sample may be comprised within a second set of PTRS resource samples. In some aspects, the first set of PTRS resource samples may be adjacent to the second set of PTRS resource samples. Each of the first and second sets of PTRS resource samples may include m adjacent PTRS resource samples along a delay axis in the delay-Doppler domain. In some aspects, the first set of PTRS resource samples may include at least two PTRS resource samples that are spaced apart along the delay axis by n delay-Doppler domain samples. For example, the second set of PTRS resource samples may include at least two PTRS resource samples that are spaced apart along the delay axis by n delay-Doppler domain samples, where m is an integer greater than zero, and n is an integer greater than zero. In some aspects, at least one of m or n may be a function of at least one of a modulation and coding scheme (MCS) for the PTRS, a number of resources blocks (RBs) including the PTRS capable of being processed by the first network node, or a phase noise at the first network node. In some aspects, at least one of m or n may be proportionally related to the at least one of the MCS for the PTRS, the number of RBs including the PTRS capable of being processed by the network node (e.g., UE), or the phase noise at the network node (e.g., UE). In some aspects, the OTFS may further include a plurality of demodulation reference signal (DMRS) samples that are adjacent along the delay axis and a Doppler axis in the delay-Doppler domain. The first symbol may include at least one DMRS sample of the first set of DMRS samples and the second symbol may include at least one DMRS sample of the first set of DMRS samples. In some aspects, the first set of PTRS resource samples and the second set of PTRS resource samples, closest to the first set of DMRS samples, may be spaced apart from the plurality of DMRS samples by n doppler-domain samples or by z doppler-Domain samples, where z is different from n and is an integer greater than zero. The z PTRS resource samples may be along the delay axis.

As illustrated at1216, the first network node1202may process the plurality of symbols in the delay-Doppler domain. The first network node may process the plurality of symbols in the delay-Doppler domain by performing at least one of channel estimation or channel equalization on the plurality of symbols in the delay-Doppler domain, for example as disclosed inFIGS.11A and11B.

As illustrated at1218, the first network node1202may transform the plurality of symbols, for example as disclosed inFIGS.9-11. In some aspects, the first network node may transform the plurality of symbols from the delay-Doppler domain to a time domain. In some aspects, the first network node may transform the processed plurality of symbols to a time domain. The PTRS may be measured based on the transformed symbols in the time domain.

As illustrated at1220, the first network node1202may perform phase noise tracking for a data channel, for example as disclosed inFIGS.9-11. The first network node may perform the phase noise tracking for the data channel based on the measured PTRS.

As illustrated at1222, the first network node1202may apply phase noise compensation on the transformed symbols in the time domain, for example as disclosed inFIGS.11A and11B. The first network node may apply the phase noise compensation on the transformed symbols in the time domain to perform the phase noise tracking for the data channel based on the measured PTRS. In some aspects, to perform the phase noise tracking for the data channel based on the measured PTRS, the first network node may convert the time domain samples back to the delay-Doppler domain of the OTFS. The first network node1202, at1224, may communicate with the second network node1204.

FIG.13is a flowchart1300of a method of wireless communication performed by a first network node. In some aspects, the first network node may comprise a UE, a base station, an apparatus, a device, or a computing system configured to perform any techniques described herein. In some aspects, the method may be performed by a UE or a component of a UE (e.g., the UE104; the apparatus1502; the baseband processor1504, which may include the memory360and which may be the entire UE350or a component of the UE350, such as the TX processor368, the RX processor356, and/or the controller/processor359). In some aspects, the method may be performed by a base station or a component of a base station (e.g., the base station102/180; the apparatus1502; the baseband processor1504, which may include the memory376and which may be the entire base station310or a component of the base station310, such as the TX processor316, the RX processor370, and/or the controller/processor375). One or more of the illustrated operations may be omitted, transposed, or contemporaneous.

At1302, the first network node may measure a PTRS using an OTFS including a delay-Doppler domain, for example as disclosed inFIGS.9-11. For example,1302may be performed by PTRS component1540of apparatus1502. The OTFS may include a plurality of symbols in the delay-Doppler domain based on the PTRS. A first symbol of the plurality of symbols may include a first PTRS resource sample having a first value in the delay-Doppler domain. A second symbol of the plurality of symbols may include a second PTRS resource sample having a second value in the delay-Doppler domain. The first PTRS resource sample may be adjacent to the second PTRS resource sample.

The first value or the second value may comprise a complex number comprising a real component and an imaginary component. In some instances, the imaginary component may have a value of zero (0), while the real component may have a value greater than zero (0). In some instances, at least one of the imaginary component or the real component may have a non-zero value. In some aspects, the first value and the second value may be based on a sequence. The sequence may include a Zadoff Chu (ZC) sequence or a pseudo-random noise (PN) sequence. In some aspects, the first value of the first PTRS resource sample may be non-zero and the second value of the second PTRS resource sample may be zero.

The first symbol may include a first plurality of PTRS resource samples in the delay-Doppler domain. Each respective PTRS resource sample of the first plurality of PTRS resource samples may have a respective value. In some aspects, the first plurality of PTRS resource samples may include the first PTRS resource sample. In some aspects, the second symbol may include a second plurality of PTRS resource samples in the delay-Doppler domain. Each respective PTRS resource sample of the second plurality of PTRS resource samples may have a respective value. The second plurality of PTRS resource samples may include the second PTRS resource sample. In some aspects, the respective value may be non-zero for each respective PTRS resource sample in the first plurality of PTRS resource samples. For example, the first and second values may be non-zero and zero, respectively. In some aspects, the respective value may be zero for each respective PTRS resource sample in the second plurality of PTRS resource samples. In some aspects, the respective value for each respective PTRS resource sample in the first plurality of PTRS resource samples may be based on a sequence. In some aspects, the respective value for each respective PTRS resource sample in the second plurality of PTRS resource samples may be based on the sequence.

The first symbol may include a first plurality of PTRS resource samples in the delay-Doppler domain. Each respective PTRS resource sample of the first plurality of PTRS resource samples may have a respective value. In some aspects, the first plurality of PTRS resource samples may include the first PTRS resource sample. Each respective symbol of the plurality of symbols that is different from the first symbol may include a respective plurality of PTRS resource samples in the delay-Doppler domain. Each respective PTRS resource sample of each respective symbol that is different from the first symbol may have a respective value. In some aspects, the respective value may be non-zero for each respective PTRS resource sample in the first plurality of PTRS resource samples. In some aspects, the respective value may be zero for each respective PTRS resource sample of each respective symbol that is different from the first symbol. In some aspects, the respective value for each respective PTRS resource sample in the first plurality of PTRS resource samples may be based on a sequence. In some aspects, the respective value for each respective PTRS resource sample of each respective symbol that is different from the first symbol may be based on the sequence.

The first symbol may include a first plurality of PTRS resource samples spaced apart along a delay axis in the delay-Doppler domain. In some aspects, the first plurality of PTRS resource samples may include the first PTRS resource sample. In some aspects, the second symbol may include a second plurality of PTRS resource samples spaced apart along the delay axis in the delay-Doppler domain. The second plurality of PTRS resource samples may include the second PTRS resource sample. In some aspects, the PTRS resource samples of the first plurality of PTRS resource samples may be spaced apart along the delay axis in the delay-Doppler domain by n delay-Doppler domain samples, where n may be an integer greater than zero. In some aspects, the PTRS resource samples of the second plurality of PTRS resource samples may be spaced apart along the delay axis in the delay-Doppler domain by n delay-Doppler domain samples, where n may be an integer greater than zero. In some aspects, the n delay-Doppler domain samples may be data samples in the delay-Doppler domain.

The first symbol may include a first plurality of PTRS resource samples that are adjacent along a delay axis in the delay-Doppler domain and a second plurality of PTRS resource samples that are adjacent along the delay axis in the delay-Doppler domain. The first plurality and second plurality of PTRS resource samples of the first symbol may be spaced apart along the delay axis in the delay-Doppler domain by n delay-Doppler domain samples. The second symbol may include a first plurality of PTRS resource samples that are adjacent along the delay axis in the delay-Doppler domain and a second plurality of PTRS resource samples that are adjacent along the delay axis in the delay-Doppler domain. The first plurality and second plurality of PTRS resource samples of the second symbol may be spaced apart along the delay axis in the delay-Doppler domain by n delay-Doppler domain samples, where n is an integer greater than zero. In some aspects, one of the first plurality or the second plurality of PTRS resource samples of the first symbol may include the first PTRS resource sample. In some aspects, one of the first plurality or the second plurality of PTRS resource samples of the second symbol may include the second PTRS resource sample. In some aspects, the first plurality and second plurality of PTRS resource samples of the first symbol may each include m adjacent PTRS resource samples, where m is an integer greater than zero. In some aspects, the first plurality and second plurality of PTRS resource samples of the second symbol may each includes m adjacent PTRS resource samples, where m is an integer greater than zero.

The first symbol may include a first plurality of demodulation reference signal (DMRS) samples. The second symbol may include a second plurality of DMRS samples. In some aspects, the first plurality of DMRS samples may be adjacent to the second plurality of DMRS samples in the delay-Doppler domain.

The first PTRS resource sample may be comprised within a first set of PTRS resource samples and the second PTRS resource sample may be comprised within a second set of PTRS resource samples. In some aspects, the first set of PTRS resource samples may be adjacent to the second set of PTRS resource samples. Each of the first and second sets of PTRS resource samples may include m adjacent PTRS resource samples along a delay axis in the delay-Doppler domain. In some aspects, the first set of PTRS resource samples may include at least two PTRS resource samples that are spaced apart along the delay axis by n delay-Doppler domain samples. For example, the second set of PTRS resource samples may include at least two PTRS resource samples that are spaced apart along the delay axis by n delay-Doppler domain samples, where m is an integer greater than zero, and n is an integer greater than zero. In some aspects, at least one of m or n may be a function of at least one of a modulation and coding scheme (MCS) for the PTRS, a number of resources blocks (RBs) including the PTRS capable of being processed by the first network node, or a phase noise at the first network node. In some aspects, at least one of m or n may be proportionally related to the at least one of the MCS for the PTRS, the number of RBs including the PTRS capable of being processed by the network node (e.g., UE), or the phase noise at the network node (e.g., UE). In some aspects, the OTFS may further include a plurality of demodulation reference signal (DMRS) samples that are adjacent along the delay axis and a Doppler axis in the delay-Doppler domain. The first symbol may include at least one DMRS sample of the first set of DMRS samples and the second symbol may include at least one DMRS sample of the first set of DMRS samples. In some aspects, the first set of PTRS resource samples and the second set of PTRS resource samples, closest to the first set of DMRS samples, may be spaced apart from the plurality of DMRS samples by n doppler-domain samples or by z doppler-Domain samples, where z is different from n and is an integer greater than zero. The z PTRS resource samples may be along the delay axis.

At1304, the first network node may perform phase noise tracking for a data channel, for example as disclosed inFIGS.9-11. For example,1304may be performed by phase noise component1546of apparatus1502. The first network node may perform the phase noise tracking for the data channel based on the measured PTRS.

FIG.14is a flowchart1400of a method of wireless communication performed by a first network node. In some aspects, the first network node may comprise a UE, a base station, an apparatus, a device, or a computing system configured to perform any techniques described herein. In some aspects, the method may be performed by a UE or a component of a UE (e.g., the UE104; the apparatus1502; the baseband processor1504, which may include the memory360and which may be the entire UE350or a component of the UE350, such as the TX processor368, the RX processor356, and/or the controller/processor359). In some aspects, the method may be performed by a base station or a component of a base station (e.g., the base station102/180; the apparatus1502; the baseband processor1504, which may include the memory376and which may be the entire base station310or a component of the base station310, such as the TX processor316, the RX processor370, and/or the controller/processor375). One or more of the illustrated operations may be omitted, transposed, or contemporaneous.

At1402, the first network node may transmit information indicating a highest density PTRS that the first network node may process. For example,1402may be performed by PTRS component1540of apparatus1502. The first network node may transmit the information indicating the highest density PTRS that the first network node may process to a second network node. The PTRS included in the OTFS may be based on the information transmitted. In some aspects, the second network node may comprise a UE, a base station, an apparatus, a device, or a computing system configured to perform any techniques described herein. In some aspects, the information may be transmitted in UCI.

At1404, the first network node may receive information indicating a density of the PTRS. For example,1404may be performed by PTRS component1540of apparatus1502. The first network node may receive the information indicating the density of the PTRS from a second network node. The PTRS may be measured based on the information received from the second network node. In some aspects, the information is received in DCI.

At1406, the first network node may receive the PTRS. For example,1406may be performed by PTRS component1540of apparatus1502. The first network node may receive the PTRS from the second network node.

At1408, the first network node may convert the PTRS. For example,1408may be performed by PTRS component1540of apparatus1502. The first network node may convert the PTRS into the delay-Doppler domain of the OTFS.

At1410, the first network node may measure a PTRS using an OTFS including a delay-Doppler domain, for example as disclosed inFIGS.9-11. For example,1410may be performed by PTRS component1540of apparatus1502. The OTFS may include a plurality of symbols in the delay-Doppler domain based on the PTRS. A first symbol of the plurality of symbols may include a first PTRS resource sample having a first value in the delay-Doppler domain. A second symbol of the plurality of symbols may include a second PTRS resource sample having a second value in the delay-Doppler domain. The first PTRS resource sample may be adjacent to the second PTRS resource sample.

The first value or the second value may comprise a complex number comprising a real component and an imaginary component. In some instances, the imaginary component may have a value of zero (0), while the real component may have a value greater than zero (0). In some instances, at least one of the imaginary component or the real component may have a non-zero value. In some aspects, the first value and the second value may be based on a sequence. The sequence may include a ZC sequence or a PN sequence. In some aspects, the first value of the first PTRS resource sample may be non-zero and the second value of the second PTRS resource sample may be zero.

The first symbol may include a first plurality of PTRS resource samples in the delay-Doppler domain. Each respective PTRS resource sample of the first plurality of PTRS resource samples may have a respective value. In some aspects, the first plurality of PTRS resource samples may include the first PTRS resource sample. In some aspects, the second symbol may include a second plurality of PTRS resource samples in the delay-Doppler domain. Each respective PTRS resource sample of the second plurality of PTRS resource samples may have a respective value. The second plurality of PTRS resource samples may include the second PTRS resource sample. In some aspects, the respective value may be non-zero for each respective PTRS resource sample in the first plurality of PTRS resource samples. For example, the first and second values may be non-zero and zero, respectively. In some aspects, the respective value may be zero for each respective PTRS resource sample in the second plurality of PTRS resource samples. In some aspects, the respective value for each respective PTRS resource sample in the first plurality of PTRS resource samples may be based on a sequence. In some aspects, the respective value for each respective PTRS resource sample in the second plurality of PTRS resource samples may be based on the sequence.

The first symbol may include a first plurality of PTRS resource samples in the delay-Doppler domain. Each respective PTRS resource sample of the first plurality of PTRS resource samples may have a respective value. In some aspects, the first plurality of PTRS resource samples may include the first PTRS resource sample. Each respective symbol of the plurality of symbols that is different from the first symbol may include a respective plurality of PTRS resource samples in the delay-Doppler domain. Each respective PTRS resource sample of each respective symbol that is different from the first symbol may have a respective value. In some aspects, the respective value may be non-zero for each respective PTRS resource sample in the first plurality of PTRS resource samples. In some aspects, the respective value may be zero for each respective PTRS resource sample of each respective symbol that is different from the first symbol. In some aspects, the respective value for each respective PTRS resource sample in the first plurality of PTRS resource samples may be based on a sequence. In some aspects, the respective value for each respective PTRS resource sample of each respective symbol that is different from the first symbol may be based on the sequence.

The first symbol may include a first plurality of PTRS resource samples spaced apart along a delay axis in the delay-Doppler domain. In some aspects, the first plurality of PTRS resource samples may include the first PTRS resource sample. In some aspects, the second symbol may include a second plurality of PTRS resource samples spaced apart along the delay axis in the delay-Doppler domain. The second plurality of PTRS resource samples may include the second PTRS resource sample. In some aspects, the PTRS resource samples of the first plurality of PTRS resource samples may be spaced apart along the delay axis in the delay-Doppler domain by n delay-Doppler domain samples, where n may be an integer greater than zero. In some aspects, the PTRS resource samples of the second plurality of PTRS resource samples may be spaced apart along the delay axis in the delay-Doppler domain by n delay-Doppler domain samples, where n may be an integer greater than zero. In some aspects, the n delay-Doppler domain samples may be data samples in the delay-Doppler domain.

The first symbol may include a first plurality of PTRS resource samples that are adjacent along a delay axis in the delay-Doppler domain and a second plurality of PTRS resource samples that are adjacent along the delay axis in the delay-Doppler domain. The first plurality and second plurality of PTRS resource samples of the first symbol may be spaced apart along the delay axis in the delay-Doppler domain by n delay-Doppler domain samples. The second symbol may include a first plurality of PTRS resource samples that are adjacent along the delay axis in the delay-Doppler domain and a second plurality of PTRS resource samples that are adjacent along the delay axis in the delay-Doppler domain. The first plurality and second plurality of PTRS resource samples of the second symbol may be spaced apart along the delay axis in the delay-Doppler domain by n delay-Doppler domain samples, where n is an integer greater than zero. In some aspects, one of the first plurality or the second plurality of PTRS resource samples of the first symbol may include the first PTRS resource sample. In some aspects, one of the first plurality or the second plurality of PTRS resource samples of the second symbol may include the second PTRS resource sample. In some aspects, the first plurality and second plurality of PTRS resource samples of the first symbol may each include m adjacent PTRS resource samples, where m is an integer greater than zero. In some aspects, the first plurality and second plurality of PTRS resource samples of the second symbol may each includes m adjacent PTRS resource samples, where m is an integer greater than zero.

The first symbol may include a first plurality of DMRS samples. The second symbol may include a second plurality of DMRS samples. In some aspects, the first plurality of DMRS samples may be adjacent to the second plurality of DMRS samples in the delay-Doppler domain.

The first PTRS resource sample may be comprised within a first set of PTRS resource samples and the second PTRS resource sample may be comprised within a second set of PTRS resource samples. In some aspects, the first set of PTRS resource samples may be adjacent to the second set of PTRS resource samples. Each of the first and second sets of PTRS resource samples may include m adjacent PTRS resource samples along a delay axis in the delay-Doppler domain. In some aspects, the first set of PTRS resource samples may include at least two PTRS resource samples that are spaced apart along the delay axis by n delay-Doppler domain samples. For example, the second set of PTRS resource samples may include at least two PTRS resource samples that are spaced apart along the delay axis by n delay-Doppler domain samples, where m is an integer greater than zero, and n is an integer greater than zero. In some aspects, at least one of m or n may be a function of at least one of an MCS for the PTRS, a number of RBs including the PTRS capable of being processed by the first network node, or a phase noise at the first network node. In some aspects, at least one of m or n may be proportionally related to the at least one of the MCS for the PTRS, the number of RBs including the PTRS capable of being processed by the network node (e.g., UE), or the phase noise at the network node (e.g., UE). In some aspects, the OTFS may further include a plurality of DMRS samples that are adjacent along the delay axis and a Doppler axis in the delay-Doppler domain. The first symbol may include at least one DMRS sample of the first set of DMRS samples and the second symbol may include at least one DMRS sample of the first set of DMRS samples. In some aspects, the first set of PTRS resource samples and the second set of PTRS resource samples, closest to the first set of DMRS samples, may be spaced apart from the plurality of DMRS samples by n doppler-domain samples or by z doppler-Domain samples, where z is different from n and is an integer greater than zero. The z PTRS resource samples may be along the delay axis.

At1412, the first network node may process the plurality of symbols in the delay-Doppler domain. For example,1412may be performed by process component1542of apparatus1502. The first network node may process the plurality of symbols in the delay-Doppler domain by performing channel estimation and channel equalization on the plurality of symbols in the delay-Doppler domain, for example as disclosed inFIGS.11A and11B.

At1414, the first network node may transform the plurality of symbols, for example as disclosed inFIGS.9-11. For example,1414may be performed by transform component1544of apparatus1502. In some aspects, the first network node may transform the plurality of symbols from the delay-Doppler domain to a time domain. In some aspects, the first network node may transform the processed plurality of symbols to a time domain. The PTRS may be measured based on the transformed symbols in the time domain.

At1416, the first network node may perform phase noise tracking for a data channel, for example as disclosed inFIGS.9-11. For example,1416may be performed by phase noise component1546of apparatus1502. The first network node may perform the phase noise tracking for the data channel based on the measured PTRS.

At1418, the first network node, to perform the phase noise tracking for the data channel based on the measured PTRS, may apply phase noise compensation on the transformed symbols in the time domain, for example as disclosed inFIGS.11A and11B. For example,1418may be performed by phase noise component1546of apparatus1502. In some aspects, to perform the phase noise tracking for the data channel based on the measured PTRS, the first network node may convert the time domain samples back to the delay-Doppler domain of the OTFS.

FIG.15is a diagram1500illustrating an example of a hardware implementation for an apparatus1502. The apparatus1502may be a UE, a component of a UE, or may implement UE functionality. In some aspects, the apparatus1502may include a baseband processor1504(also referred to as a modem) coupled to a cellular RF transceiver1522. In some aspects, the apparatus1502may further include one or more subscriber identity modules (SIM) cards1520, an application processor1506coupled to a secure digital (SD) card1508and a screen1510, a Bluetooth module1512, a wireless local area network (WLAN) module1514, a Global Positioning System (GPS) module1516, or a power supply1518. The baseband processor1504communicates through the cellular RF transceiver1522with the UE104and/or BS102/180. The baseband processor1504may include a computer-readable medium/memory. The computer-readable medium/memory may be non-transitory. The baseband processor1504is responsible for general processing, including the execution of software stored on the computer-readable medium/memory. The software, when executed by the baseband processor1504, causes the baseband processor1504to perform the various functions described supra. The computer-readable medium/memory may also be used for storing data that is manipulated by the baseband processor1504when executing software. The baseband processor1504further includes a reception component1530, a communication manager1532, and a transmission component1534. The communication manager1532includes the one or more illustrated components. The components within the communication manager1532may be stored in the computer-readable medium/memory and/or configured as hardware within the baseband processor1504. The baseband processor1504may 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 apparatus1502may be a modem chip and include just the baseband processor1504, and in another configuration, the apparatus1502may be the entire UE (e.g., see350ofFIG.3) and include the additional modules of the apparatus1502.

The communication manager1532includes a PTRS component1540that is configured to transmit information indicating a highest density PTRS that the first network node may process, e.g., as described in connection with1402ofFIG.14. The PTRS component1540may be further configured to receive information indicating a density of the PTRS, e.g., as described in connection with1404ofFIG.14. The PTRS component1540may be further configured to receive the PTRS, e.g., as described in connection with1406ofFIG.14. The PTRS component1540may be further configured to convert the PTRS, e.g., as described in connection with1408ofFIG.14. The PTRS component1540may be further configured to measure a PTRS using an OTFS including a delay-Doppler domain, e.g., as described in connection with1302ofFIG.13or1410ofFIG.14. The communication manager1532further includes a process component1542that is configured to process the plurality of symbols in the delay-Doppler domain, e.g., as described in connection with1412ofFIG.14. The communication manager1532further includes a transform component1544that is configured to transform the plurality of symbols, e.g., as described in connection with1414ofFIG.14. The communication manager1532further includes a phase noise component1546that is configured to perform phase noise tracking for a data channel, e.g., as described in connection with1304ofFIG.13or1416ofFIG.14. The phase noise component1546may be further configured to apply phase noise compensation on the transformed symbols in the time domain, e.g., as described in connection with1418ofFIG.14.

As shown, the apparatus1502may include a variety of components configured for various functions. In one configuration, the apparatus1502, and in particular the baseband processor1504, includes means for measuring a PTRS using an OTFS including a delay-Doppler domain. The OTFS includes a plurality of symbols in the delay-Doppler domain based on the PTRS. A first symbol of the plurality of symbols includes a first PTRS resource sample having a first value in the delay-Doppler domain. A second symbol of the plurality of symbols includes a second PTRS resource sample having a second value in the delay-Doppler domain. The first PTRS resource sample is adjacent to the second PTRS resource sample. The apparatus includes means for performing phase noise tracking for a data channel based on the measured PTRS. The apparatus further includes means for receiving, from a second network node, the PTRS. The apparatus further includes means for converting the PTRS into the delay-Doppler domain of the OTFS. The apparatus further includes means for transforming the plurality of symbols from the delay-Doppler domain to a time domain. The apparatus further includes means for processing the plurality of symbols in the delay-Doppler domain by performing channel estimation and channel equalization on the plurality of symbols in the delay-Doppler domain. The apparatus further includes means for transforming the processed plurality of symbols to a time domain. The PTRS is measured based on the transformed symbols in the time domain. The apparatus further includes means for applying phase noise compensation on the transformed symbols in the time domain. The apparatus further includes means for transmitting, to a second network node, information indicating a highest density of PTRS that the first network node can process. The PTRS included in the OTFS is based on the transmitted information. The apparatus further includes means for receiving, from a second network node, information indicating a density of the PTRS. The PTRS is measured based on the received information. The apparatus further includes means for converting the time domain samples back to the delay-Doppler domain of the OTFS. The means may be one or more of the components of the apparatus1502configured to perform the functions recited by the means. As described supra, the apparatus1502may 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 the controller/processor359configured to perform the functions recited by the means.

Aspect 1 is a method of wireless communication performed by a first network node comprising measuring a PTRS using an OTFS including a delay-Doppler domain, wherein the OTFS includes a plurality of symbols in the delay-Doppler domain based on the PTRS, wherein a first symbol of the plurality of symbols includes a first PTRS resource sample having a first value in the delay-Doppler domain, wherein a second symbol of the plurality of symbols includes a second PTRS resource sample having a second value in the delay-Doppler domain, and wherein the first PTRS resource sample is adjacent to the second PTRS resource sample; and performing phase noise tracking for a data channel based on the measured PTRS.

Aspect 2 may be combined with Aspect 1 and includes that the first value and the second value are based on a sequence.

Aspect 3 may be combined with any of Aspects 1 and 2 and includes that the sequence includes a ZC sequence or a PN sequence.

Aspect 4 may be combined with any of Aspects 1-3 and includes that the first value of the first PTRS resource sample is non-zero and the second value of the second PTRS resource sample is zero.

Aspect 5 may be combined with any of Aspects 1-4 and includes that the first symbol includes a first plurality of PTRS resource samples in the delay-Doppler domain, wherein each respective PTRS resource sample of the first plurality of PTRS resource samples has a respective value, wherein the first plurality of PTRS resource samples includes the first PTRS resource sample, wherein the second symbol includes a second plurality of PTRS resource samples in the delay-Doppler domain, wherein each respective PTRS resource sample of the second plurality of PTRS resource samples has a respective value, wherein the second plurality of PTRS resource samples includes the second PTRS resource sample.

Aspect 6 may be combined with any of Aspects 1-5 and includes that the respective value is non-zero for each respective PTRS resource sample in the first plurality of PTRS resource samples, and wherein the respective value is zero for each respective PTRS resource sample in the second plurality of PTRS resource samples.

Aspect 7 may be combined with any of Aspects 1-6 and includes that the respective value for each respective PTRS resource sample in the first plurality of PTRS resource samples is based on a sequence, and wherein the respective value for each respective PTRS resource sample in the second plurality of PTRS resource samples is based on the sequence.

Aspect 8 may be combined with any of Aspects 1-7 and includes that the first symbol includes a first plurality of PTRS resource samples in the delay-Doppler domain, wherein each respective PTRS resource sample of the first plurality of PTRS resource samples has a respective value, wherein the first plurality of PTRS resource samples includes the first PTRS resource sample, wherein each respective symbol of the plurality of symbols that is different from the first symbol includes a respective plurality of PTRS resource samples in the delay-Doppler domain, and wherein each respective PTRS resource sample of each respective symbol that is different from the first symbol has a respective value.

Aspect 9 may be combined with any of Aspects 1-8 and includes that the respective value is non-zero for each respective PTRS resource sample in the first plurality of PTRS resource samples, and wherein the respective value is zero for each respective PTRS resource sample of each respective symbol that is different from the first symbol.

Aspect 10 may be combined with any of Aspects 1-9 and includes that the respective value for each respective PTRS resource sample in the first plurality of PTRS resource samples is based on a sequence, and wherein the respective value for each respective PTRS resource sample of each respective symbol that is different from the first symbol is based on the sequence.

Aspect 11 may be combined with any of Aspects 1-10 and includes that the first symbol includes a first plurality of PTRS resource samples spaced apart along a delay axis in the delay-Doppler domain, wherein the first plurality of PTRS resource samples includes the first PTRS resource sample, wherein the second symbol includes a second plurality of PTRS resource samples spaced apart along the delay axis in the delay-Doppler domain, and wherein the second plurality of PTRS resource samples includes the second PTRS resource sample.

Aspect 12 may be combined with any of Aspects 1-11 and includes that PTRS resource samples of the first plurality of PTRS resource samples are spaced apart along the delay axis in the delay-Doppler domain by n delay-Doppler domain samples, wherein PTRS resource samples of the second plurality of PTRS resource samples are spaced apart along the delay axis in the delay-Doppler domain by n delay-Doppler domain samples, and wherein n is an integer greater than zero.

Aspect 13 may be combined with any of Aspects1-12and includes that the n delay-Doppler domain samples are data samples in the delay-Doppler domain.

Aspect 14 may be combined with any of Aspects 1-13 and includes that the first symbol includes a first plurality of PTRS resource samples that are adjacent along a delay axis in the delay-Doppler domain and a second plurality of PTRS resource samples that are adjacent along the delay axis in the delay-Doppler domain, wherein the first plurality and second plurality of PTRS resource samples of the first symbol are spaced apart along the delay axis in the delay-Doppler domain by n delay-Doppler domain samples, wherein the second symbol includes a first plurality of PTRS resource samples that are adjacent along the delay axis in the delay-Doppler domain and a second plurality of PTRS resource samples that are adjacent along the delay axis in the delay-Doppler domain, wherein the first plurality and second plurality of PTRS resource samples of the second symbol are spaced apart along the delay axis in the delay-Doppler domain by n delay-Doppler domain samples, wherein n is an integer greater than zero, wherein one of the first plurality or the second plurality of PTRS resource samples of the first symbol includes the first PTRS resource sample, and wherein one of the first plurality or the second plurality of PTRS resource samples of the second symbol includes the second PTRS resource sample.

Aspect 15 may be combined with any of Aspects 1-14 and includes that the first plurality and second plurality of PTRS resource samples of the first symbol each includes m adjacent PTRS resource samples, wherein the first plurality and second plurality of PTRS resource samples of the second symbol each includes m adjacent PTRS resource samples, wherein m is an integer greater than zero.

Aspect 16 may be combined with any of Aspects 1-15 and includes that the first symbol includes a first plurality of DMRS samples, and wherein the second symbol includes a second plurality of DMRS samples.

Aspect 17 may be combined with any of Aspects 1-16 and includes that the first plurality of DMRS samples is adjacent to the second plurality of DMRS samples in the delay-Doppler domain.

Aspect 18 may be combined with any of Aspects 1-17 and includes that the first PTRS resource sample is comprised within a first set of PTRS resource samples and the second PTRS resource sample is comprised within a second set of PTRS resource samples, wherein the first set of PTRS resource samples are adjacent to the second set of PTRS resource samples, wherein each of the first and second sets of PTRS resource samples include m adjacent PTRS resource samples along a delay axis in the delay-Doppler domain, wherein the first set of PTRS resource samples includes at least two PTRS resource samples that are spaced apart along the delay axis by n delay-Doppler domain samples, wherein the second set of PTRS resource samples includes at least two PTRS resource samples that are spaced apart along the delay axis by n delay-Doppler domain samples, wherein m is an integer greater than zero, and wherein n is an integer greater than zero.

Aspect 19 may be combined with any of Aspects 1-18 and includes that at least one of m or n is a function of at least one of an MCS for the PTRS, a number of RB s including the PTRS capable of being processed by the first network node, or a phase noise at the first network node.

Aspect 20 may be combined with any of Aspects 1-19 and includes that the OTFS further includes a plurality of DMRS samples that are adjacent along the delay axis and a Doppler axis in the delay-Doppler domain, wherein the first symbol includes at least one DMRS sample of a first set of DMRS samples and the second symbol includes at least one DMRS sample of the first set of DMRS samples, and wherein the first set of PTRS resource samples and the second set of PTRS resource samples are spaced apart from the plurality of DMRS samples by n doppler-domain samples or by z doppler-Domain samples, wherein z is different from n and is an integer greater than zero, wherein z PTRS resource samples are along the delay axis.

Aspect 21 may be combined with any of Aspects 1-20 and includes receiving, from a second network node, the PTRS; and converting the PTRS into the delay-Doppler domain of the OTFS.

Aspect 22 may be combined with any of Aspects 1-21 and includes transforming the plurality of symbols from the delay-Doppler domain to a time domain.

Aspect 23 may be combined with any of Aspects 1-22 and includes processing the plurality of symbols in the delay-Doppler domain by performing channel estimation and channel equalization on the plurality of symbols in the delay-Doppler domain; and transforming the processed plurality of symbols to a time domain, wherein the PTRS is measured based on the transformed symbols in the time domain.

Aspect 24 may be combined with any of Aspects 1-23 and includes that performing phase noise tracking for the data channel based on the measured PTRS includes applying phase noise compensation on the transformed symbols in the time domain.

Aspect 25 may be combined with any of Aspects 1-24 and includes transmitting, to a second network node, information indicating a highest density of PTRS that the first network node can process, wherein the PTRS included in the OTFS is based on the transmitted information.

Aspect 26 may be combined with any of Aspects 1-25 and includes receiving, from a second network node, information indicating a density of the PTRS, wherein the PTRS is measured based on the received information.

Aspect 27 may be combined with any of Aspects 1-26 and includes that the information is received in DCI.

Aspect 28 may be combined with any of Aspects 1-27 and includes that the information is transmitted in UCI.

Aspect 29 is a network node for wireless communication including at least one processor coupled to a memory, the at least one processor configured to implement the method as set forth in aspects 1-28.

Aspect 30 is a network node for wireless communication including means for implementing the method as set forth in aspects 1-28.

Aspect 31 is a computer-readable medium having code stored thereon that, when executed by a first network node, causes the first network node to implement the method as set forth in aspects 1-28.